Oe) Seg Co ses ie Tel Kp, CER Ce Avanty TECHNICAL REPORT CERC-87-13 ANNUAL DATA SUMMARY AND OPEAUoce” CLIMATOLOGICAL EVALUATION CERC FIELD RESEARCH FACILITY, 1985 Volume | MAIN TEXT AND APPENDIXES A AND B by Herman C. Miller, Adele Militello, Michael W. Leffler, William E. Grogg, Michael M. Dominguez Coastal Engineering Research Center. DEPARTMENT OF THE ARMY Waterways Experiment Station, Corps of Engineers PO Box 631, Vicksburg, Mississippi 39180-0631 DOCUMENT LIBRARY “ Woods Hole Oceanographic Institution September 1987 Final Report Approved For Public Release, Distribution Unlimited Prepared for DEPARTMENT OF THE ARMY US Army Corps of Engineers Washington, DC 20314-1000 Ueey Soin yas Ge eal Kp, CGEjZCs Avant¥ TECHNICAL REPORT CERC-87-13 ANNUAL DATA SUMMARY AND pitt dilate CLIMATOLOGICAL EVALUATION CERC FIELD RESEARCH FACILITY, 1985 Volume | MAIN TEXT AND APPENDIXES A AND B by Herman C. Miller, Adele Militello, Michael W. Leffler, William E. Grogg, Michael M. Dominguez Coastal Engineering Research Center. DEPARTMENT OF THE ARMY Waterways Experiment Station, Corps of Engineers PO Box 631, Vicksburg, Mississippi 39180-0631 DOCUMENT | _ LIBRARY \ Woods Hole Oceanographic Institution September 1987 Final Report Approved For Public Release, Distribution Unlimited Prepared for DEPARTMENT OF THE ARMY US Army Corps of Engineers Washington, DC 20314-1000 When this report is no longer needed return it to the originator. The findings in this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents. The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. SECURITY CLASSIFICATION OF THIS PAGE Form Approved _ OMB No 0704-0188 REPORT DOCUMENTATION PAGE Exp. Date Jun 30, 1986 1a. REPORT SECURITY CLASSIFICATION 1b. RESTRICTIVE MARKINGS Unclassified 2a. SECURITY CLASSIFICATION AUTHORITY 3. DISTRIBUTION AVAILABILITY OF REPORT | Approved for public release; distribution unlimited. 5. MONITORING ORGANIZATION REPORT NUMBER(S) 2b. DECLASSIFICATION / DOWNGRADING SCHEDULE 8. PERFORMING ORGANIZATION REPORT NUMBER(S) Technical Report CERC-87-13 6a. NAME OF PERFORMING ORGANIZATION USAEWES, Coastal Engineering Research Center 6c. ADDRESS (City, State, and ZIP Code) 6b. OFFICE SYMBOL (If applicable) WESCV 7a. NAME OF MONITORING ORGANIZATION 7b. ADDRESS (City, State, and ZIP Code) PO Box 631 Vicksburg, MS 39180-0631 8a. NAME OF FUNDING / SPONSORING ORGANIZATION US Army Corps of Engineers 8c. ADDRESS (City, State, and ZIP Code) 8b. OFFICE SYMBOL (If applicable) 9. PROCUREMENT INSTRUMENT IDENTIFICATION NUMBER 10. SOURCE OF FUNDING NUMBERS PROGRAM PROJECT TASK NO. NO 11. TITLE (Include Security Classification) ELEMENT NO. Annual Data Summary and Climatological Evaluation; CERC Field Research Facility, 1985; Volume I: Main Text and Appendixes A and B 12. PERSONAL AUTHOR(S) See reverse 13a. TYPE OF REPORT 13b. TIME COVERED 14. DATE OF REPORT (Year, Month, Day) |15. PAGE COUNT Final report FROM TO September 1987 221 16. SUPPLEMENTARY NOTATION WORK UNIT ACCESSION NO Washington, DC 20314-1000 See reverse 17 COSATI CODES SUBGROUP 18. SUBJECT TERMS (Continue on reverse if necessary and identify by block number) See reverse, 19. ABSTRACT (Continue on reverse if necessary and identify by block number) This report provides basic data. and summaries for the measurements made during 1985 at the US Army Engineer Waterways Experiment Station (WES) Coastal Engineering Research Center's (CERC's) Field Research Facility (FRF) in Duck, N. C. The report includes com- parisons of the present year's data to those of previous years and cumulative statistics from 1980 to the present. Summarized in this report are meteorological and oceanographic data, monthly bathy- metric survey results, samples of quarterly aerial photography, and descriptions and hourly data for 13 storms that occurred during the year. The year was highlighted by the close passage of tropical storms Ana in July and Henri in September and Hurricanes Claudette in August and Gloria in September. Waves over 6 m were measured, at a location 6 km from shore, during Hurricane Gloria. 20. DISTRIBUTION / AVAILABILITY OF ABSTRACT 21. ABSTRACT SECURITY CLASSIFICATION Gd UNCLASSIFIED/UNLIMITEO © SAME AS RPT CI oric users Unclassified 22a. NAME OF RESPONSIBLE INDIVIDUAL 22b. TELEPHONE (Include Area Code) | 22c. OFFICE SYMBOL DD FORM 1473, 84 mar 83 APR edition may be used until exhausted. SECURITY CLASSIFICATION OF THIS PAGE All other editions are obsolete. OCC 0301 O091ebbL 3 Unclassified SECURITY CLASSIFICATION OF THIS PAGE 12. PERSONAL AUTHOR(S) (Continued). Miller, Herman C.; Militello, Adele; Leffler, Michael W.; Grogg, William E.; Dominguez, Michael M. 16. SUPPLEMENTARY NOTATION (Continued). A limited number of copies of Volume II was published under separate cover. Copies of Volume I (this report and Appendixes A and B) are available from National Technical Information Service, 5285 Port Royal Road, Springfield, VA 22161. 18. SUBJECT TERMS (Continued). Meteorologic research--statistics (LC) Oceanographic research--statistics (LC) Oceanographic research stations--North Carolina--Duck (LC) Water waves--statistics (LC) 19. ABSTRACT (Continued). This report is seventh in a series of annual summaries of data collected at the The six previous reports are as follows: a. CERC Miscellaneous Report 82-16, which summarizes data collected during 1977-79. b. Technical Report CERC-84-1, which summarizes data collected during 1980. c. Technical Report CERC-85-3, which summarizes data collected during 1981. d. Technical Report CERC-86-5, which summarizes data collected during 1982. e. Technical Report CERC-86-9, which summarizes data collected during 1983. f. Technical Report CERC-86-11, which summarizes data collected during 1984. These reports are available from the WES Technical Report Distribution Section of the Technical Information Center, Vicksburg, Miss. SECURITY CLASSIFICATION OF THIS PAGE PREFACE Data and data summaries presented herein were collected during 1985 and compiled at the US Army Engineer Waterways Experiment Station (WES) Coastal Engineering Research Center's (CERC's) Field Research Facility (FRF) in Duck, N. C. This report is the seventh in a series of annual FRF data summaries carried out under CERC's Waves and Coastal Flooding Program. The report was prepared by Mr. Herman C. Miller, Oceanographer, FRF, under direct supervision of Mr. Curtis Mason, former Chief, FRF Group, Engi- neering Development Division (EDD), and Mr. Thomas W. Richardson, Chief, EDD; and under general supervision of Dr. James R. Houston and Mr. Charles C. Calhoun, Jr., Chief and Assistant Chief, CERC, respectively. Ms. Adele Militello, Computer Scientist, assisted with software development and data analysis; and Messrs. Michael W. Leffler, Computer Programmer Analyst, as-— sisted with data collection and analysis; William E. Grogg, Jr., Electronics Technician, assisted with instrumentation; and Michael M. Dominguez, Amphibi- ous Vehicle Operator, assisted with data collection. The National Oceanic and Atmospheric Administration/National Ocean Service maintained the tide gage and provided statistics for summarization. In addition, special thanks are extended to Messrs. William A. Birkemeier, Research Hydraulic Engineer, for his supervision of the FRF sur- veying program and Jeff Halpin, Computer Scientist, for his help in converting analysis and summarization software to the new computer system. This report was edited by Ms. Shirley A. J. Hanshaw, Information Products Division, Infor- mation Technology Laboratory, WES. Commander and Director of WES during the publication of this report was COL Dwayne G. Lee, CE; Technical Director was Dr. Robert W. Whalin. CONTENTS RPAH A GEiameteteteletelelotelaeteisteletetenelete ood0CODODD000R LIST LIST PART PART PART PART PART PART PART PART PART REFERENCES........ OI WNL 5 oo cud DD aDCOD CODCOD OGOOGDONDNE OR PETCURE SE yereieleretele 5000000000000000000 eocoeceeoeeeeeseoeee2ee eee ee ee eo IS TORAURODIWC MON 4 5.000060:0000000000000000000000000000006000500000 ° BECKKEEOUINE Go CODD DO OODD DDD DOD DDDDDODDDDDDD ODO OODDDDDODNDOOOODN0NDNDN Ongemlnaestom @ INGMOES oooc0 cD OCC D DDD OOO OOD OD OKO OADDDOODDDDD0D0NNS AMVealaioalilaiesy Oi WANs gaccaodn do DDD DDD DDO D OD aDDDDDDODGDDDOODKONDNON IICS MORI AOROILOEN Go Gd0adDd DoD dD ODDDNDDODDNdDNN000N S0000000000000000 Malia NEMPEEENEWIED 5 Do G0 G Ob O00bGDODD00N0N Atmospheric Pressure.......cceccccecce Pre@SaloaticeretlOMs oogago0000 00D D0 D0DDOONE Watinel Sjoecel eine! WaleaeeLOMs occ0c0cc0cc00000000000000000000000000000 WIS — WANES 6 0060060000000000000000000000000000000000000600 BODOG Measurement mEnsiErumemtSierereleleteleteleleielelclololelercieleliclenelelcrelkehelelerelelele 90000000 Digital Data Analysis and Summarization.......ccccccccccccccccece RAGKMILER 5 50 FOO COORD OD OOO OU UO ODD OD OUD OUODOODO OOO OOOO ODD ODDO OGOOO000 IV: (GUINIINMIIS 5 oo oD Od DDD ODR0DCD0000000 ODS STV aE TON Sliereveyevovon sie: once vevereterereneveKel oveieiesoxcderexclous/etesieveuekeusieverenelevepenensiejsvere RES UAE Sere evercetou cl oigeiere) oh ariatianaverlaheZeibeliartoces areeel eWellorle:/e:se),eviehieeie\ eGelisusi eve iavevelouere-eecereiotece V: IID IAS ANID) MMIII IGINVIFILS oo op 00000 DDG DDD DD ODDO DDDDDO00DD0D00000N Measurement Instrument......ccccccce eoeeeeeeo eee eee eee ee eo eo ew 8 ee 8 8 FREES ULES ayas eat orate ave voralie’ ation atareneb one hel ehe re hovoveret eben wivetiulcetasede: ct araltel aPeleitenetetaraievensteite cle ters VI: RUNIEISIR CHUNVACINSIRILSIEIUCS 6 60 00 00000000 D000 dDDODDODDRODDDD0000000 TeMPeCTatuLre..cesscrecccccccccccccccccccccrcccccscsscrccccsccssccne Walelnilllstieyyo o pa ond 000 ODD DDO d DDO OOD ODDO DD ODD DODD DDDDDOOUODORGODNDNE WEMBILEVooo0doC DODD DDD DODD DOG OD DOO DDDD DOD DDDOODDDDDODDDDODNDCOODDODDNDN VII: SWIRWINES 6 0000000000000000090000000000000000000000000000000000 BoetronellevaltlonmhastoreleSlrverevcteiererchelolevetencleleucslorersleloneierelelelelene 6000000 ENEMIES 5.0 00000000000000000000000006000000000000000000000000060 WILICILE — PASLONOERVNPIEN 6 og 00g 0000000000000 Ma@reZUL IINMOKEOLEEDING > og00d000000000000 BELEN MCOBEEIMS o oo. DODD OCOD DD ODD ODDDDD ODDO DODDDDDDD DDD OOOO ODDDON0 IDS | SIONS 6 goo dd000000GDDOGCbH0000000 INAAINIDIDC ANG SOIAWNG IYMIY\G Go GoGG00000000000 APPBNDIDKE 138 SWORN WNWAG oooggg oo ObodoOCU DDO OO OND DODD ODO UD ODDO OODOOUGOOOS APPENDIX C*: WAVE DATA..... JOoDODOODOOODDDD OOOO DODO OOD DDR DODOODONODRR * A limited number of copies of Appendix C (Volume II) was published under separate cover. Copies are available from National Technical Information Service, 5285 Port Royal Road, Springfield, Va. 22161. 3 C10 Cll c12 C13 C14 C15 C16 C17 C18 C19 LIST OF TABLES Page 135 Deven Axyeatilmlostilatieyys ocogaco000n000 poDoaDdDDDDODDCOON 5000000000 192 Monthly Mean Air Temperature and Atmospheric Pressure SEGEMBGENCS 5 co 00 b00DD DDD OOD DD OOO NOD DOOD UD DD ODO OODDGODDDDDDNDNDOOODO 16 eacipltcaeilom SteateilsiclCSooqc0000000000 sveltelisnecs p000000000000000000000 18 Resultant Wind Speed and Directions Relative to True North....... 25 Spectral Band and Peak Period SpecificationsS......cceccccscscrcccece 32 Resultant Wave Height and Directions.........ccccccceceee o00000000 41 Joint Distribution of Wave Height Versus Period, 1980-1985....... 45 Annual and Monthly Longshore Surface Currents at the FRF......... 49 IGS) Wiel Uiewwmte SieaEdtselesgooocssoccc0gb0a000K60 cO000000000000000 55) Mean SunaalcemWaltceras Ghiaizaleterell sitll Cloepersrlerelcterehelerehelonchelelelelelelsnchel lelenelenele 59 Aerial Photography Inventory for 1985......... o0000000000000000 0 68 lave EZace histories tor IM85>oscq0c000 0000000000000 D0DDG00DD0000000 C4 1985 Mean, Standard Deviation, and Extreme H and T for CAseNGOS MeN. MMe te er bis ante hiie opisrctuicontida iowtedisctudeedauee C6 1985 Annual Joint Distribution of H Versus T for Gage BD eth d re ia Bus ce ee AEE adios ly aon ee aE C8 1985 Seasonal Joint Distribution of Ha Versus T for Gage COS INE eS EP aeS ooe Gepeabcal Bae eee me eA NS c8 1985 Monthly Joint Distribution of H Versus T EGR CARS COS Ete Sc reac cas Gig AM aust am men ate a aa ORM UM Eee 3-011) 1985 Persistence of Hi. for Gage 625..... p0000DD00DDDDDD0NDDDODN C20 1980 Through 1985 Mean, Standard Deviation, and Extreme qT and a for EAR O25 500000000000 00000000 0D DOOD ODODDDODODODDNDDNDS G25 1980 Through 1985 Annual Joint Distribution of H a Versus T FOI EAEG O25 500000000 0000000 0000000000000 000000D000000000000000 C27 1980 Through 1985 Seasonal Joint Distribution of H aa Versus us for GAGA C25 ocnc00nd0400 000000 CODD ODDO OO OOO 900000000000 aes C27 1980 Through 1985 Monthly Joint Distribution of H ae Versus T for Cage ©25500000000000000000%00000000000000000000000 p000000 R C29 1980 Through 1985 Persistence of Hoe OS EAA O2ZDo6000000000000 C39 1985 Mean, Standard Deviation, and Extreme Eee andy for Eae ©3065 o65000060600060006000000000600000000000000500000000000 C60 1985 Annual Joint Distribution of H Versus T for CEVA. (ASO Mees een FM Milan WER Sie RNR nL mea eh C62 1985 Seasonal Joint Distribution of H a Versus T for Gage BVO SOPs AS AE SiO oR hth oe eA ta A DO ed Ae C62 1985 Monthly Joint Distribution of Ho Versus T for Gage (BEY) cc 5 tt AGRA oho RAO Lz am OR C64 1985 Persistence of He HOE CAGE O3Vscocoadccg000c000GD00000000 C72 1980 Through 1985 Mean, Standard Deviation, and Extreme H and T, for Gage CSO ener ere ere corte nents onthe Gentae MG CH 1980 Through 1985 Annual Joint Distribution of H Versus T FO MGR CVO SU etere Sh vel ersceh ice raseisto Na Tia GaSe te eee ovat RCIA sds ART UCTS 1980 Through 1985 Seasonal Joint Distribution of H Versus Te for Gage GENO) Ae Son A ROE RE tn Bee ER SO ees Pe eR C75 No. C20 C21 C22 C23 C24 C25 C26 C27 C28 C29 C30 C31 C35 C36 m eo} OMNDURWNE | 1980 Through 1985 Monthly Joint Distribution of H ad Versus T ore GaGa O8O05o000000b00000000000000000 sts tobe Retalomeiete JRE RMS wo RRR 1980 Through 1985 Persistence of Hae HOKMGALEMOS Okielelerehercnerenerevetene 1985 Mean, Standard Deviation, and Extreme Lie and T for Gag eno Olereteeleterevousie elolereseirereire S00000000 obo00000 0000000000000 00I00 660 1985 Annual Joint Distribution of H Versus T for mo Pp Cage O40c000 0000000000 0b 0D Dob O OOO bOGOCGOOOOOONDN dO000000000000000 1985 Seasonal Joint Distribution of He Versus T for Gage GAD cnet RCN ARINC: ASR ac Ait lest hel AL ee ob oleate 1985 Monthly Joint Distribution of H Versus T for mo Pp CaGe: O40.5.6 BSSS 65 do USEING Ol TODA ESTOS OS COUGH OO OOO SOOO eS oo 1985 Persistence of Hie EOL O40 5 .o60bb0000b00G00000000000 1985 Mean, Standard Deviation, and Extreme H and T for mo P GCABOVOA Diareitexereislioeieiotoletee lateileds, ohehave onebsualeceheds ls Gehvs,eBeuehe rs tetete suchouctekebore relates 1985 Annual Joint Distribution of H Versus T for Gage GAS sacs ancrsiors oes aot Geel RUG Bh MAReMeEm mee cer he cmt hme coer: 1985 Seasonal Joint Distribution of H Versus T for Gage GAS. AL ERRREAERE Lc dec Maa btnunceeenk eueRe RCE cic kecm hea : 1985 Monthly Joint Distribution of H Versus T for Gage CES our eee CEMA RERUN RRR ARENEL ca RGh ECE ARRE haar fs 1985 Persistence of Hi ye HOD GABON OAS eres ekelerseahae omctarekekeueleketeseteletete 1980 Through 1985 Mean, Standard Deviation, and Extreme H and Ts for Gage IAS) SAN td wept kerlyy, cance te Andie eR Sots andl eh 1980 Through 1985 Annual Joint Distribution of H Versus T for Gage CEES eee LAAT Aaa ee et OE a Sea ey Sey 1980 Through 1985 Seasonal Joint Distribution of H Versus = ForpCage G45e ORR, Mabhhdlahe nk seeaueR eas Be cone ueckeeek 1980 Through 1985 Monthly Joint Distribution of H Versus T for Gage (GLAS tdesaorstch basnetpuoben a isin ain Meng lone aes plurianaet oaort it 12 1980 Through 1985 Persistence of Hes HOM Cagen OG) se lcreilersislelcrerelole LIST OF FIGURES ERED CatealOn) MAP! a ie ey/oi'ehie\ oj 0's) sehiaisaliecoksiieiion che) o1eeveuiel 40qcccdc000b0900000000000000000000000 Comparison of surface currents at the pier end........cccccccccee Comparison of surface currents at the midsurf........ccccccccccee Comparison of surface currents at the beach......cc.cccccccccerces MEAN EUSAEACEa Cumecemess, WOON > 6 o5g00nb00dd000000000 00000000000 Monthly tide and water level statistics, 1978-1985...........ee0.- Comparison of hourly tide heights and daily high and low water level distributions, 1979-1984 versus 1985.....cccccccccccccses Distribution of hourly tide heights and daily high and low water LEVELS, WOPQH=1LYIDs condo cocccc0 ood aDbNO DODO OOD OSODOODDDDDO00G0000 Daily sea surface water temperatures, 1985.....ccccccrsceccccccce 0 Comparison of mean surface water temperatures......esecccccccroce Distribution of surface water temperatures, 1980-1985....... a0000 Daily sea surface water visibility, 1985.......cccccccsccccccccee Comparison of mean surface water visibility.........ccccccccccece Distribution of surface water visibility, 1980-1985..........0.e. Daily sea surface water density, 1985......cccccccccccrccccccccce Comparison of mean sea surface water densSity.....cccccccccccsccee Distribution of surface water density, 1981-1985..........c2.-e0% Permanent trough under the FRF pier (14 February 1985)........... Time-history of bottom elevations at selected locations under (Eln@ THRE PMPs ooo0oc occ OD DODD ODDO DDO ODDDDODDOOODDDDDOODDDNDOONDNN ercalagil pmnoromezyooyy icllsieime WINES 5 oagg000d 000 000000000D000000000000 Sample aerial photograph taken 9 February 1985......... o000000000 Sample photographs of the FRF beach taken 17 August 1985......... LA WEDEWATESY DAES MIEEIST 5 0 cco G00 00D DDD DODD D DDD OODDDDDOODDDOOONOOO0N 23 iNoreilil DREN MOLE > 500000000000000000000000000000000000000000000 14 February to 23 April change diagram.......ccceccccccccccescvce LS) Wulsy DAEMNMMIEERV>s oc ocb 00D ODD ODD ODDO DDD DODO RDOUOOODDDDOOONDCONON 23) INsyeatil fe@ WS) gwillsy Glemesa chigierceimsooo0ng coo d0c4o005b000UDO00DN0NN ZL NORUSIE DAEMPIAEIRVS ccooC00bC OOD ODDO OD dD DO ODDDO DOO ODDO ODO OOODO0S 5) gwukhy COQ Bil Angmete Eleinge cleo poas0gddq0d0000D000bK00000000 243} SQOEEMO@OIE KEN MIBIERo oo cn DOD UD GADD DODD DDD ODDDDDNOOOOOODDb GDS 21 August to 28 September change diagram.......ccccccccccccccecece UG) DECEMIDAIE DAEMNAMOERY>5 cob go0cDDDD 0000 DD DODD DO00DD DDD OOO OOODDDNDON 28 September -to 19 December change diagram......cecccscccsrcccces Soin Glatea itor 3A demmery W855 500000006000000000000000050000000 Seon data itor 12 welprmarcy IMSS oogoocccnddod0 005000 KaG DOO DO0OG00000 Stim Gatea ire@ie 22623} Ween WED coool o9000c0d00g0d0000000000000000 Cll C12 C13 C14 C15 C16 C17 c18 C19 C20 C21 C22 C23 C24 C25 C26 C27 Storm Storm Storm Storm Storm Storm Storm Storm Storm Storm 1985 mean, standard deviation, and extreme data data data data data data data data data data for 14- for 29 IS WNowesttl WIS oso gdo000K AMmetil WDSSoggo 50500000 6 oe 3) Wes, ISSS>ooo6oGgoo000K G00 ate rom 2 Anemsie ID8Dooodoocodcc00e for 27 FO! ZiS22 Oetc@inare WOSH5s64ogo0d0cc0c0600 September 1985.......... for 31 October through 2 November 1985.........-2+e0- for 4-5 November 1985....-ccccce for 1 December 1985..... Seenehovexeus Foe 7 Dacembare WOES sesosebaccacésa0accb000dG0Ob0D0D00N00E Time-history of HS and By 1E@pe GA O56 000000000000000050000 Gage ©25.550000000000000000060000000060000 1985 annual cumulative distribution of Hea 1985 eoceoceeeee ee ee oe eecececeee H and T for mo P for Gage 625..... seasonal cumulative distribution of Hees for Gage 625...... 1985 monthly cumulative distribution of Hey for Gage 625....... 1985 annual distribution of os 1985 seasonal distribution of - Fore (aa OLDo500000000000000000'00 Foe CABG O2D55005600000000000000 1985 monthly distribution of tO CEN O25 5500600000 Da0000000 1985 annual and seasonal wave roses........ 600000000 0000000000000 1985 monthly wave roS€S......ececcccecs po000d000000 S0000000000000 1980 through 1985 mean, standard deviation, and extreme H and T, toe GAS OZDsccbc00on0000000 00000000 Big Bata Mire eee 1980 through 1985 annual cumulative distribution of Hints for Gage 625...... 1980 through 1985 seasonal cumulative distribution of Bi for Gage 625.... 1980 through 1985 monthly cumulative distribution of Hino for Gage 625..... 1980 1980 1980 1980 1980 Time-history of H and T mo P 1985 mean, standard deviation, and extreme O8MGcoagcc0e Gage 1985 1985 1985 monthly cumulative distribution of Ho 1985 1985 through 1985 through 1985 through 1985 through 1985 through 1985 Spectra for waves annual cumulative distribution of Hee annual distribution of T seasonal distribution of x monthly distribution of for Gage 625...... for Gage 625..... is for Gage 625...... annual and seasonal wave roseS..... 50000000006 monthly wave roses...... S2 ip Cama O2556cc000000 eoceooceceeeeeeee2e2 82082020280 8 © © 8 ecoeoeeeveeeee eee 8 © © 8 Oe H and T for mo 2) Oe EaAZe O30cadoa00000000000000000 for Gage 630........ seasonal cumulative distribution of HO for Gage 630...... annual distribution of a seasonal distribution of ONS GRYKS) WSKY5 cagcao5d00g0000000 for Gage 630....... crore CHE O05 G50600000000000000 C61 C68 C69 C71 C71 No. C28 C29 C30 C31 C32 C33 C34 C35 C36 C37 C38 C39 c40 c41 C42 C43 C44 C45 C46 C47 c48 C49 C50 C51 C52 €53 Page 1980 through 1985 mean, standard deviation, and extreme Ho and i fOr CARE O30oqgoncccngn 50 00bDCDDDDDDDDDDDDDDOODOOENNDONR C74 1980 through 1985 annual cumulative distribution of a for Gage (SYD Ss pe Spe SN SEBS ea a0 ea i ep ca er Ata C81 1980 through 1985 seasonal cumulative distribution of H oa for EAGO O3Mc6c06cd0cc000d cond oon ds 0b db 00D DDO 0DDDD GOOD DDD OOOO OOO06O0 c81 1980 through 1985 monthly cumulative distribution of H for CARON S ON net eee et tt ete oe eae co ueaieee cee MCee 1980 through 1985 annual distribution of a for Gage 630....... C84 1980 through 1985 seasonal distribution of t for Gage 630..... C84 Time-history of Rie and a toe Gaga OOo 505050000000000000000 C86 1985 mean, standard deviation, and extreme lee and T for EAA OFMoccc000000 000006000 OOD DODD OOODD ODO DDD DOO OO OD ODO OOOO 00ON C88 1985 annual cumulative distribution of Ho for Gage 640........ c95 1985 seasonal cumulative distribution of Haak for Gage 640...... c95 1985 monthly cumulative distribution of He for Gage 640....... C96 1985 annual distribution of - Or Cage OAMoc0cc0000G00000000006 c98 1985 seasonal distribution of - Oe (aga WAD>o0000000000000000 C98 Time-history of He and ue for Cage OADoo000c0000000000000000 C100 1985 mean, standard deviation, and extreme H and T for GapemOA Sin mee Te Te OTM ah ia esto ea a tock oe! CLOM 1985 annual cumulative distribution of Ho for Gage 645........ C109 1985 seasonal cumulative distribution of Hoa for Gage 645...... c109 1985 monthly cumulative distribution of Ho for Gage 645....... C110 1985 annual distribution of ue toe Casa Of5oaccoccccn000d000000 C112 1985 seasonal distribution of Le Foe CAE O4Dcccocc0c0ng000000C C112 1980 through 1985 mean, standard deviation, and extreme H and T, for Gage GUS es MARAIS ESA AI SSAct Mos TOOs RS OOaL CIE 1980 through 1985 annual cumulative distribution of ae for Gage (BAG Seas Ne SN ne RS eR a A ee n= en C122 1980 through 1985 seasonal cumulative distribution of H for CaOMOU Ste MeN rra een eA ine cm eae Bihar eet rete hi badt ACT) 1980 through 1985 monthly cumulative distribution of qo for Gage (BING, & 1s Bie, 2s Bola IN 2 tb RORY eal, Ear ee SP ara C123 1980 through 1985 annual distribution of a for Gage 645....... C125 1980 through 1985 seasonal distribution of ae for Gage 645..... C125 ANNUAL DATA SUMMARY AND CLIMATOLOGICAL EVALUATION CERC FIELD RESEARCH FACILITY, 1985 PART I: INTRODUCTION Background 1. The US Army Engineer Waterways Experiment Station (WES) Coastal Engineering Research Center's (CERC's) Field Research Facility (FRF), located on 712,250 square metres at Duck, N. C. (Figure 1), consists of a 561-m-long research pier and accompanying office and field support buildings. The FRF is located near the middle of Currituck Spit along a 100-km unbroken stretch of shoreline extending south of Rudee Inlet, Va., to Oregon Inlet, N. C. The FRF is bordered by the Atlantic Ocean to the east and Currituck Sound to the west. The Facility is designed to (a) provide a rigid platform from which waves, currents, water levels, and bottom elevations can be measured, especially dur- ing severe storms; (b) provide CERC with field experience and data to comple- ment laboratory and analytical studies and numerical models; (c) provide a manned field facility for testing new instrumentation; and (d) serve as a per- manent field base of operations for physical and biological studies of the site and adjacent region. 2. The research pier is a reinforced concrete structure supported on 0.9-m-diam steel piles spaced 12.2 m apart along the pier's length and 4.6 m apart across the width. The piles are embedded approximately 20 m below the ocean bottom. The pier deck is 6.1 m wide and extends from behind the dune- line to about the 6-m water depth contour at a height of 7.8 m above the National Geodetic Vertical Datum (NGVD). The pilings are protected against sand abrasion by concrete erosion collars and against corrosion by a cathodic system. 3. An FRF Measurements and Analysis program has been established to collect basic oceanographic and meteorological data at the site, reduce and analyze these data, and publish the results. 4, This report is the seventh in a series of annual reports and summa- rizes the data collected during 1985. Data for previous years are summarized by Miller (1982 and 1984) and Miller et al. (1985, 1986a, 1986b, and 1986c). SVYFILLVH Ayui904 youDesay IMVIAVSIHI dew uotjes0,T aya wy og O02 O} aN °[ ean3sTty Mu®S.S9.SL N.u9VS.00.9F - ALINIOWS HOWV3SIY 07319 \ 10 Organization of Report 5. This report is organized as follows: Glo leensie. dl - Introduction. Io leebere IIL - Meteorology. Go Pebsig WINE SEMIS Glo WRawaie ID - Currents. Go Webee \W/ - Tides and Water Levels. gd) Inches WIL - Water Characteristics. g. Part VII - Surveys. h. Part VIII - Photography. Sho | Pewele 10K - Storms. In each part of this report, the respective instruments used for monitoring the meteorological or oceanographic conditions are briefly described. These instruments are interfaced with the primary data acquisition system, a Data General Corporation (Westboro, Mass.) NOVA-4 minicomputer located in the FRF laboratory building. More detailed explanations of the instrument design and operation may be found in Miller (1980). Additionally, each part of the re- port presents data collection and analysis procedures as well as results. 6. As a result of reader comments on prior reports, this report has been reorganized. Now, with the instrument descriptions and the data collec- tion and analysis procedures in the same section as the data, it will be more convenient to find the information necessary for proper interpretation of the results. Another revision in the report involves the wave data which in the past has been included in Appendix B but is now being published under separate cover as Appendix C (Volume II) which contains gage histories; wave height, period, and direction distributions and other statistics; and spectra during storms. As usual, readers’ comments on the format and usefulness of the data presented are encouraged. Availability of Data 7. Table 1 is intended as a quick reference guide to show the dates for which various types of data are available. In addition to the wave data sum- maries in the main text and Appendix B, more extensive summaries for each of the gages are provided under separate cover as discussed above. 11 Table 1 1985 Data Availabilit 1 [2] 3]4]5 [6 [7] 8] 9 pols] 12fisfia]is|ieh zhslis|20|21[22}23]24]25]26 [so] 31[32]33]34[35|36]37] 36[39]40]4 42]a3]a]45] 46] 47]48]49]50] 51]52] i SS a ae ee ee ee aa te | 4 WEATHER ANEMOMETER ATM PRESSURE AIR TEMPERATURE WV PRECIPITATION OFFSHORE GAGE 630 NEARSHORE GAGE 640 AAAA AA PIER END GAGE 625 PIER NEARSHORE GAGE 645 CURRENTS PIER END SURF BEACH TIDE WATER CHARACTERISTICS TEMPERATURE VISIBILITY DENSITY LEGEND ia NO DATA A LESS THAN 7 DAYS OF DATA OBTAINED a FULL WEEK OF DATA OBTAINED 8. The annual data summary herein summarizes daily observations by month, season, and year to provide basic data for analysis by users. Daily observations have been reported also in the 1985 series of monthly Preliminary Data Summaries (Field Research Facility 1985) which summarize the same types of data shortly after they were collected. If individual data are needed, the user can obtain detailed information (as well as the monthly reports) from the following address: USAE Waterways Experiment Station Coastal Engineering Research Center Field Research Facility SR Box 271 Kitty Hawk, N. C. 27949 12 9. Although the data collected at the FRF are designed primarily to support ongoing CERC research, use of the data by others is encouraged. The WES/CERC Coastal Engineering Information and Analysis Center (CEIAC) is re- sponsible for storing and disseminating most of the data presented or alluded to in this report. All data requests should be in writing and addressed to: Commander and Director US Army Engineer Waterways Experiment Station ATTN: Coastal Engineering Information Analysis Center PO Box 631 Vicksburg, Miss. 39180-0631 Tidal data other than the summaries in this report can be obtained directly from the following address: National Oceanic and Atmospheric Administration National Ocean Service ATIN: Tide Analysis Branch Rockville, Md. 20852 A complete explanation of the exact data desired for specific dates and times will expedite filling any request; an explanation of how the data will be used will help CEIAC or the National Oceanic and Atmospheric Administration (NOAA) / National Ocean Service (NOS) determine if other relevant data are available. For information regarding the availability of data, contact CEIAC at (601) 634-2017. Costs for collecting, copying, and mailing will be borne by the requester. 13 PART II: METEOROLOGY 10. This section summarizes the meteorological measurements made at the FRF in 1985. A discussion of the data and a comparison with those of previous years are also presented. Appendix B contains hourly wind speed and direction and atmospheric pressure values during storm conditions. 11. Mean air temperature, atmospheric pressure, and wind speed and direction were computed based on data sampled four times per second for 20 min every 6 hr beginning at or about 0100, 0700, 1300, and 1900 eastern standard time (EST); these hours correspond to the time that the National Weather Service (NWS) creates daily synoptic weather maps. During storms, hourly data recordings were made. prior to collection, each gage signal was first ampli- fied and then biased to ensure a O- to 5-V range. Air Temperature 12. The FRF enjoys a typical marine climate which moderates the ex- tremes of both summer and winter. During the warmest months, July and August, the monthly air temperature averaged nearly 25° C. Lowest air temperatures occur during January, averaging about 5° C. Measurement instruments 13. A Yellow Springs Instrument Company, Inc. (YSI) (Yellow Springs, Ohio) electronic temperature probe with analog output interfaced to the FRF's NOVA-4 computer was operated beside the NWS's meteorological instrument shelter located 43 m behind the dune (Figure 2). To ensure proper tem- perature readings, the probe was installed 3 m above ground inside a "coolie hat" to shade it from direct sun yet provide proper ventilation. Results 14. Present year. The average air temperature for the year was 16° C. After a very cold winter, monthly mean for January was only 2.6° C, tempera- tures rose to the mid-twenties during the summer (see Table 2). Autumn temperatures remained mild through November for which the monthly mean was 1569" Ge 15. Present versus past years. In comparison to prior years, the air temperatures for 1985 were very cold during January and February, milder 14 m1 -6000 CERC METEOROLOGICAL & INSTRUMENTS == Ss. ed ee NO ee iar & coer a SB BAYLOR GAGE NO 645 No 6258 a panei: ANEMOMETER# 5 TIDE GAGE| a ¢. 3 NO 865-1370 WAVERIDER BUOY 6 KM OFFSHORE NO. 630 SWAVERIDER BUOY ‘ bea 7 KM OFFSHORE NO 640 © Figure 2. FRF gage locations 15 Table 2 Monthly Mean Air Temperature and Atmospheric Pressure Statistics Air Temperature, °C Atmospheric Pressure, mb* Month 1985 1983-1984 1983-1985 1985 1983-1984 1983-1985 Jan Zo 6.2 5.0 1012.9 LOL) 2 LOU od Feb Doll Toll 6.4 1019.8 IONS) 6 2 IOUT o# Mar 10.3 8.9 9.4 1017.7 1012.0 1014.0 Apr 16.1 13.0 14.0 MOMS ye 7 LOUZ SY 1013.9 May 19).3} 19) UY) I 1013.6 1016.4 1015.4 Jun 23.0 23.4 223} 53) 1013.8 1016.3 1015.5 Jul 2553) 26.1 25.8 1016.0 1016.9 1016.6 Aug 24.9 25.6 2353 LOU 65 1016.0 1016.5 Sep Dos) 20.3 21.0 1016.7 1018.4 1017.8 Oct IW) 6 7/ 7 o€ 1S} 55) 1019.4 1020.4 1020.0 Nov iL5)59) Hie 1363! 1016.7 1017.9 1017.5 Dec 7.0 9.4 8.6 HOLY) 1 1020.7 1020.2 Annual 16.0 5 ey/ 15.8 1016.9 1016.9 1016.8 * Multiply millibars by 100.0 to obtain pascals. during spring and autumn, and near normal during the summer, as shown in Fig- ure 3. The annual average air temperature was 0.3° C above the average for 1983 and 1984. 16. All years. The coldest month of the year is January, with an aver- age temperature of 5.0° C (Table 2). Temperatures slowly increase through March. In the spring the temperature rises more than 9° C, then it remains near 25° C through July and August. By the end of autumn the temperatures fall 17° C. The annual average temperature is consistently near 15.8° C. Atmospheric Pressure Measurement instruments 17. Electronic atmospheric pressure sensor. Atmospheric pressure was measured with a YSI electronic sensor with analog output located in the labo- ratory building at 9 m above NGVD. Data were recorded on the FRF computer. Data from this gage were compared with those from an NWS aneroid barometer at least once a week to ensure proper operation. 16 30.0 YEAR MEAN, °C x 85 16.0 Puna 0 83-84 15.7 25.0 20.0 15.0 10.0 TEMPERATURE, deg c --" - 5.0 0.0 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTH Figure 3. 1985 mean monthly air temperatures 18. Microbarograph. A Weathertronics, Incorporated (Sacramento, Calif.), recording aneroid sensor (microbarograph) located in the laboratory building also was used to continuously record atmospheric pressure variation. 19. The microbarograph was compared daily with the NWS aneroid barome- ter, and adjustments were made as necessary. Maintenance of the micro- barograph consisted of inking the pen, changing the chart paper, and winding the clock every 7 days. During the summer, a meteorologist from the NWS checked and verified the operation of the barometer. 20. The microbarograph was read and inspected daily using the following procedure: a. The pen was zeroed (where applicable). b. The chart time was checked and corrected, if necessary. - Daily reading was marked on the chart for reference. £& d. The starting and ending chart times were recorded, as necessary. e. New charts were installed when needed. 17 Results 21. Present year. Average atmospheric pressure for the year was 1016.6 mb. The lowest monthly average pressures occurred in January, May, and June, while the highest occurred in February, March, October, and December (Table 3). Total Month 1985, mm Jan 126 Feb 68 Mar 35) Apr 0 May 35 Jun 62 Jul 67 Aug 30 Sep 71 Oct 143 Nov 145 Dec 4 Annual 786 Monthly avg. 66 22. Present versus past years. 1985 was 0.3 mb lower than in prior years. 94 86 98 111 88 Tih Table 3 Mean 1978- 1984, mm Precipitation Statistics 1978- 1985, mm Maxima, mm 180 127 168 182 239 130 200 220 160 143 145 131 (1985) (1985) 1978-1985 Extremes Minima, mm 35 (1985) 0 (1985) 35 (1985) 30 (1985) 20 26 4 (1985) The average atmospheric pressure for Although February through April had significantly higher monthly mean pressures (Figure 4) the largest dif- ference (6.3 mb below climatology) was the very low pressures experienced in January. 23. All years. Typically the monthly mean atmospheric pressures are lowest during March and April and highest in October and December. average is 1016.8 mb, very near standard atmospheric pressure. 18 The annual 1026.0 YEAR MEAN, mb x 85 1016.6 1024.0 o 83-84 1016.9 1022.0 1020.0 1018.0 1016.0 PRESSURE, mb 1014.0 1012.0 1010.0 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTH Figure 4. Mean monthly atmospheric pressure Precipitation 24. Precipitation is generally well distributed throughout the year, averaging 104 cm annually. Precipitation from midlatitude cyclones predominates in the winter, while local convection (thunderstorms) accounts for most of the summer rainfall. Measurement instruments 25. Electronic rain gage. A Belfort Instrument Company (Baltimore, Md.) 30-cm weighing rain gage, located near the instrument shelter 47 m behind the dune, measured daily precipitation. According to the manufacturer, the in- strument's accuracy was 0.5 percent for precipitation amounts less than 15 cm and 1.0 percent for amounts greater than 15 cm. 26. The rain gage was inspected daily, and the analog chart recorder was maintained by the procedures listed in paragraph 19. 27. Plastic rain gage. A Edwards Manufacturing Company (Alberta Lea, Minn.) True Check 15-cm-capacity clear plastic rain gage with a 0.025-cm 19 resolution was used to monitor the performance of the weighing rain gage. This gage, located near the weighing gage, was checked daily, and very few discrepancies were identified throughout the year. Results 28. Present year. The annual total was 786 mm for an average of 66 mm per month. Precipitation during 1985 was poorly distributed throughout the year (Table 3). January had a total of 126 mm; April was dry; both October and November received over 140 mm; and December had only 4 mn. 29. Present versus past years. In comparison to records since 1978, there was substantially less precipitation during 1985. Monthly average totals are typically 25 percent higher, and the precipitation is more evenly distributed throughout the year (as shown in Figure 5). 200.0 YEAR MEAN,mm x 85 66.0 175.0 o 80-84 88.0 75.0 PRECIPITATION, mm =) (=) (—) 50.0 25.0 0.0 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTH Figure 5. Mean monthly precipitation 30. All years. There were five monthly minima during 1985, including three in a row for March through May (see Table 3). Ironically, there were two maxima in October and November. 20 Wind Speed and Direction 31. Winds at the FRF are dominated by tropical maritime air masses which create low to moderate, warm southern breezes; Arctic and Polar air masses which produce cold winds from northerly directions; and smaller scale cyclonic, low pressure systems, which originate either in the tropics (and move north along the coast) or on land (and move eastward offshore). The dom- inant wind direction changes with season, being generally from northern direc- tions in the fall and winter and from southern directions in the spring and summer. The annual resultant wind direction is from the north-northwest. It is common for fall and winter storms (northeasters) to produce winds with average speeds in excess of 15 m/sec. Measurement instrument 32. Winds were measured on top of the laboratory building at an eleva- tion of 19.1 m (Figure 2) using a Weather Measure Corporation (Sacramento, Calif.) Skyvane Model W102P anemometer. Wind speed and direction data were incorporated into the automated data collection and analysis program and were collected continuously on a strip-chart recorder. The anemometer manufacturer specifies an accuracy of +0.45 m/sec below 13 m/sec and 3 percent at speeds above 13 m/sec, with a threshold of 0.9 m/sec. Wind direction accuracy is +2 deg with a resolution of less than 1 deg. The anemometer is calibrated semiannually at the National Bureau of Standards in Gaithersburg, Md., and is within the manufacturer's specifications. 33. Annual, seasonal, and monthly joint probability distributions of wind speed versus direction were computed. Wind speeds were resolved into 3-m/sec intervals, while the directions were at 22.5-deg intervals (i.e. 16-point compass direction specifications). These distributions are presented as wind "roses," such that the length of the petal represents the frequency of occurrence of wind blowing from the specified direction, and the width of the petal is indicative of the speed in 3-m/sec intervals. Resultant directions and speeds were also determined by vector averaging the data. Results 34. Present year. Winds during the year blew primarily from the north- eastern and southwestern quadrants as shown in Figure 6. The wind blew from north through east-northeast 40.8 percent of the time and south-southwest through west-southwest 26.5 percent of the time. Wind speed exceeded 10 m/sec Za N 337.50.0 995 315.0 45.0 292.5 qi f Vd ce) & -> W SE dhs dine tl 90.0E 270.0 = . am - 225.0 135.0 202.5 180.0 9-9 S 1985 SPEED 1.5 m/s DIRECTION 11 deg N 337.50.0 995 315.0 45.0 292.5 au 7 Py aie 270.0 = = Sore oY / cake onli 225.0 135.0 202.5 180.0 97-9 S 1980-1984 SPEED 0.8 m/s DIRECTION 350 deg W —— oe 0 10 20 30 40 FREQUENCY,% Figure 6. Comparison of annual wind roses, 1985 versus 1980-1984 22 N N 337.5 0.0 22.5 337.5 0.0 22.5 315.0 f 45.0 315.0 45.0 67.5 67.5 292.5 q 2, 292.5 a | AN atte W oan ie 90.0E W70.0 = = 90.0 Se [* L 112.5 x A j \ 112.5 225.0 135.0 225.0 135.0 202.5 180.0 '°7-> 202.5 180.0 7-> iS) Ss JAN=—MAR 1985 APR-JUN 1985 SPEED 1.9 m/s SPEED 0.3 m/s DIRECTION 340 deg DIRECTION 152 deg N N 315.0 f 315.0 ’ ae, oe ms inno Wena had 3 90.0E Wein oH = = 90.0E a Ti " ag 112.5 247.5 a} 1* 112.5 225.0 135.0 225.0 135.0 202.5 180.0 97:5 202.5 180.0 7"> Ss S) JUL-SEP 1985 OCT—DEC 1985 SPEED 1.5 m/s SPEED 2.6 m/s DIRECTION 23 deg DIRECTION 13 deg SPEED,m/sec Te}ySaSSR oollibe+ SS @® @® — —— oe 0 10 20 30 40 FREQUENCY, % Figure 7. Seasonal wind roses, 1985 23 13.4 percent of the time, including three occasions when the wind speed ex- ceeded 15 m/sec. More than three out of every four times, when the speed ex- ceeded 10 m/sec, the winds blew from north through east-northeast. 35. Strong seasonal tendencies measured during the year are shown in Figure 7. During January through March the winds had a bimodal distribution approximately equally split between the northeastern quadrant and the southwestern quadrants. Wind speeds exceeded 10 m/sec 16.8 percent of the time during the season. Winds were from southerly directions in the Spring with less than 8 percent exceeding 10 m/sec. Though predominantly from the northeastern quadrant during the summer, relatively low speeds were measured 31 percent of the time from the southwestern quadrant. During October through December winds exceeded 10 m/sec 19.5 percent of the time and were predomi- nantly from northerly directions. 36. Present versus past years. In comparison to prior years there were fewer occurrences of winds from the southwestern quadrant and more from the northeastern quadrant, particularly from July through December. General differences in the distribution of wind directions can be seen in Table 4. Depending on the quadrant the resultant direction is in, the tendency for more northerly or southerly and easterly or westerly direction can be seen. For example, the annual distribution for 1985 has a resultant direction of 11 deg while the 1980 through 1984 resultant is 350, indicating both had a northerly tendency. On the other hand, during 1985 winds blew more frequently from easterly directions in comparison to prior years when there was a westerly predominance. 37. All years. Winds at the FRF tend to blow most often from the northeasterly and southwesterly quadrants (Figure 8). Predominant wind direc- tion varies with season; however, winds in excess of 10 m/sec tend to blow most often from north through east-northeast. The most significant effect the addition of the 1985 data had on the annual distribution of winds was a slightly higher frequency of winds from the northeast and a corresponding lower frequency from south-southwest. 24 Month Jan-Dec Jan-Mar Apr-Jun Jul-Sep Oct-Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Speed m/sec ih) tS) [> op¥ tot het <0 OD UI Ww wo rFPoOoOrr Ww Oeil ge are. (eu Ne WNWNrH re op ou os) 16) em 0 FP OWr OOD OowoO OW ON 1985 Direction deg 11 Table 4 25 1980-1984 Speed Direction m/sec deg Annual 0.8 350 Seasonal 1.9 351 0.9 205 0.1 79 159 1 Monthly Ds) 349 Nod 354 oS 349 0.9 219 0.9 207 0.9 190 1.8 217 ORS 21 1.8 45 yey 31 2.0 343 Drew 345 1980-1985 Speed Direction m/sec deg 0.9 358 1.9 348 Ood 201 0.5 29 Bolt 5) Doll 346 Mop) 350 1.4 352 0.6 216 0.7 198 0.9 195 eo 220 0.5 51 2.0 31 2.6 35 oO Spill Doll 334 Resultant Wind Speed and Directions Relative to True North 337.50.0 995 315.0 45.0 292.5 q 7 4 ie WwW 2770.0 = oul 90.0E 4 = = ¢ ria Yad 112.5 225.0 eS) 202.5 180.0 ©7"5 Ss 1980-1985 SPEED 0.9 m/s DIRECTION 358 deg N 337.50.0 995 315.0 } 45.0 292.5 ay F4 e78 Se Ww a) call 90.0E 270.0 p= s : use f = wy 112.5 2510 135.0 202.5 180.0 "> S JAN-MAR 1980-1985 SPEED 19 m/s DIRECTION 348 deg N 337.50.0 295 315.0 45.0 67.5 292.5 qi 2, W is ae 90.0E 270.0 (= = : a WV 112.5 Sf co 135.0 202.5 180.0 97:5 Ss APR-JUN 1980-1985 SPEED 0.7 m/s DIRECTION 201 deg FREQUENCY,% N 337.5 0.0 22.5 315.0 45.0 29225 «ff 7 bs e783 @ & oma =| 90.0E Ry cS / Li 112.5 225.0 135.0 202.5 180.0 97:5 Ss JUL-SEP 1980-1985 SPEED 0.5 m/s DIRECTION 29 deg N 337.50.0 295 315.0 45.0 292.5 AN f Fg Sig Oe, => Wenn te all 90.0£ af a? f 13” 112.5 225.0 135.0 202.5 180.0 97°5 S OCT-DEC 1980-1985 SPEED 2.1 m/s DIRECTION 5 deg Figure 8. Annual and seasonal wind roses for 1980-1985 PART III: WAVES 38. This section presents summaries of the wave data. A discussion of individual major storms is given in Part IX, and Appendix B contains hourly wave data for times when the heights se exceeded 2 m at the seaward end of the FRF pier. Appendix C (published as Volume II) provides summaries of the data for each gage, including height and period distributions, wave direction distributions, persistence tables, and spectra during storms. Signals from the wave gages were routinely sampled in accordance with guidelines indicated in paragraph 11. 39. Daily wave height and period values for Gage 630, located 6 km from shore, and Gage 625, located at the seaward end of the FRF pier, are presented in Figures 9 and 10, respectively. The annual mean wave height (measured at the seaward end of the FRF pier) is 0.9 m, with a standard deviation of 0.6 m. Although the portion of the North Carolina coast in the vicinity of the FRF experiences a fairly low frequency of occurrence of direct hurricane strikes (on the average of once every 42 years), more frequent near-misses can cause high wave conditions at the FRF. Wave height in excess of 2 m can be expected to occur 7 percent of the time, or 600 hr per year. 40. Wave periods generally vary between 6 and 12 sec, with an annual mean peak spectral period of 8.8 sec and a standard deviation of 2.8 sec. Wave periods tend to be longest during the fall and shortest during the summer. 41. Wave directions (similar to wind directions) at the FRF are season- ally distributed. Waves approach most frequently from north of the pier in the fall and winter and south of the pier in the summer, with the exception of storm waves which approach twice as frequently from north of the pier. Annu- ally, waves are approximately evenly distributed between north and south (re- sultant wave direction being almost shore-normal). Measurement Instruments Staff gages 42. Two Baylor Company (Houston, Tx.) parallel cable inductance wave gages (Gage 645 at sta 7+80 and Gage 625 at sta 19+00 (Figure 2)) were mounted on the FRF pier. Rugged and reliable, these gages require little maintenance except to keep tension on the cables and to remove any material which may if HEIGHT, m ©ONPFONFONKXRONFONFORN S& JUL 1985 JAN 1985 FEB 1985 AUG 1985 MAR 1985 SEP 1985 iS APR 1985 OCT 1985 MAY 1985 NOV 1985 LN See JUN 1985 DEC 1985 13 5 7 9 1113 15 17 19 212325 27 29311 3 5 7 9 1113 15 17 19 2123 25 27 29 31 DAY OF THE MONTH a. Wave height JAN 1985 JUL 1985 WW FEB 1985 AUG 1985 MAR 1985 SEP 1985 APR 1985 OCT 1985 eA 0 MAY 1985 NOV 1985 i. JUN 1985 DEC 1985 0 13.5 7 9 1113 15 17 19 2123.25 2729311 3 5 7 9 1113 15 17 19 2123 25 27 29 31 DAY OF THE MONTH b. Wave period Figure 9. Time-histories of wave height and period for Gage 630 28 i JAN 1985 JUL 1985 Bae NN ee GG SNR ’ FEB 1985 AUG 1985 2 0 Ui eh a Ryn ot) SA MAR 1985 SEP 1985 SD. a yaaa Side Oo! APR 1985 OCT 1985 = 2 EN Ne 0 ~ = ; MAY 1985 NOV 1985 2 0 EDN eae ee ‘~ ZS j JUN 1985 DEC 1985 2 —_—_—_—_—_—— (a /NS 13 3 7 9 11 13 15 17 19 2123 25 2729311 3 3 7 9 1113 13 17 19 21 23 25 27 29 31 DAY OF THE MONTH a. Wave height 20 JAN 1985 JUL 1985 10 20 FEB 1985 AUG 1985 10 20 MAR 1985 SEP 1985 o 10 Oo = 20 APR 1985 OCT 1985 as! NN ee 20 MAY 1985 NOV 1985 WJ veya Shey, 20 JUN 1985 DEC 1985 10 0 13 5 7 9 1113 15 17 19 212325 2729311 3 5 7 9 1113 15 17 19 2123 25 27 29 31 DAY OF THE MONTH b. Wave period Figure 10. Time-histories of wave height and period for Gage 625 29 cause an electrical short between them. They were calibrated prior to instal- lation by creating an electrical short between the two cables at known dis- tances along the cable and recording the voltage output. Electronic signal conditioning amplifiers are used to ensure that the output signals from the gages are within a O- to 5-V range. Gage accuracy is about 1 percent, with a 0.1 percent full-scale resolution. (Full scale is 9.4 m for Gage 625 and 8.5 m for Gage 645.) These gages are susceptible to lightning damage, but protective measures have been taken to minimize such occurrences. A more com- plete description of the gages' operational characteristics is given by Grogg (1986). Buoy gages 43. Two Datawell Laboratory for Instrumentation (Haarlem, The Netherlands) Waverider buoy gages (Gage 630 located 6 km and Gage 640 located 1 km from shore), measure the vertical acceleration produced by the passage of awave. The acceleration signal is double-integrated to produce a displace- ment signal which is transmitted by radio to an onshore receiver. The manu- facturer states that wave amplitudes are correct to within 3 percent of their actual value for wave frequencies between 0.065 and 0.5 Hz (corresponding 15- to 2-sec wave periods). The manufacturer specifies the error can increase to 10 percent for wave periods in excess of 20 sec. Digital Data Analysis and Summarization 44. Thompson (1977) and Harris (1974) describe the procedure used for analyzing and summarizing the digital wave data contained in this report. The procedure is based on a Fast Fourier Transform (FFT) spectral analysis of 4,096 data values (1,024 sec sampled at 4 Hz) for each file processed. 45. The program computes the first five moments of the distribution of sea surface elevations then edits the digital data file by checking for "jumps" and "spikes" and for the data points out of the O- to 5-V range. A jump is defined as a data value greater than 2.5 standard deviations from the previous data value, while a spike is a data value 5 standard deviations or more from the mean. If less than 5 jumps or spikes in a row are found, the program linearly interpolates between acceptable data and replaces the errone- ous data values. If more than 5 jumps or spikes in a row or a total of 100 bad data points for the file are found, the program stops interpolating 30 and editing. At this point, the program analyzes the data and prints a flag indicating there is a problem with the file. If the variance is less than 0.001 na the record is not analyzed. After editing, the first five moments of the distribution of sea surface elevations were again computed. A cosine bell data window was applied to increase the resolution for the energy spec-— trum of the file; use of the data window is discussed by Harris (1974). After application of the data window, the program computes the variance spectrum (proportional to the energy spectrum) using the FFT procedure. After the data files are analyzed, the results are eliminated for files that are flagged as bad or appear inconsistent with simultaneous observations from nearby gage sites. Frequently, the spectrum and/or distribution function of sea surface elevations are examined to determine if the data were acceptable. After the analysis results are edited, monthly summaries of wave heights and periods are generated. 46. Unless otherwise specified, wave height, in this report, refers to the energy-based parameter Ho (defined as four times the standard deviation of the sea surface elevations). Wave period i is defined as the period associated with the maximum energy in the spectrum which is resolved by parti- tioning the spectrum into frequency bands of equal width and determining the band with the maximum energy density. The period reported is the reciprocal of the center frequency (e.g. x = 1/frequency) of the spectral band. Since the spectral bands are of equal frequency width, namely 0.010742 Hz (i.e. 11/1,024 sec), the analysis provides uniform resolution in frequency. How- ever, the resolution in period is not uniform since the period intervals become larger for lower frequencies. Because of combination with the varying width of the period intervals, only a discrete set of period values is possi- ble (Table 5). Complete information about the energy contained in all fre- quency bands can best be obtained by inspecting the full spectrum, examples of which are included in Appendix C (Volume II) for Gage 625 during storm wave conditions. Results Present year 47. Spatial variation. The distribution of wave heights for all four gages operated during the year is shown in Figure 11. For a given frequency of occurrence, wave heights were highest at Gage 630 (located in the deepest 31 Table 5 Spectral Band and Peak Period Specifications Corresponding T Associated Upper Limit of Period with Band Frequency Band Lower Limit Center Frequency aly Not Reported Number Hz of Band, sec of Band, sec sec 6 0.065 1563) 16.8 7 0.076 USo il NAG2 15 8 0.087 Li oS 1253} 13 9 0.098 10.2 10.9 11 10 0.108 Yok 9.8 5.0 SC GAGE 625 ee ee GAGE 630 AG 2 Wea anata GAGE 640 hn ___ GAGE 645 3.0 2.0 HEIGHT, m —2 10 10° 10° 10 PERCENT GREATER THAN INDICATED Figure 11. Annual wave height distributions, 1985 water) and lowest at Gage 645 (located at the landward end of the pier), as shown in the tabulation below: Gage Number Location Depth, m 630 6 km from shore 18.0 640 1 km from shore 8.5 625 Pier end 8.0 645 Landward end of 3)05) pier 32 Refraction, bottom friction, and wave breaking contribute to the observed dif- ferences in height. During the most severe storms when the wave heights exceed 3 m at the seaward end of the pier, the surf zone (wave breaking) has been observed to extend past the end of the pier occasionally out to Gage 640. This occurrence is a major reason for the differences in the distributions between Gage 630 and the inshore gages for the highest 1 percent of the waves. The wave height statistics for the staff gage (Gage 645), located at the land- ward end of the pier, were considerably lower than those for the other gages. In all but the calmest conditions, this gage is within the breaker zone. Con- sequently, these statistics represent a lower energy wave climate. 48. The distribution of wave periods for all of the gages is shown in Figure 12. Although the distributions of wave periods for all gages were sim- ilar, Gage 630 tended to have the lowest percentage of wave periods 10 sec or longer, and Gage 645 tended to have the highest percentage of wave periods less than 6 sec. oY GAGE 625 es GAGE 630 S GAGE 640 ui 28 GAGE 645 Zz lj m 20 an re) p\ ) 15 aN ta ‘ AN Of @ y OR ay 25 1 Pa a AN © 10 Q% z g Nimo Vi AN HN 2 Y \: % mae) \s \ § > o aS HN ita PANS RS uw 5 r \ Vi Y N Y Ve & ANS OR NG INS ANS NS ARS NS 0 6 a! Ny ea 10 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 12.0 14.0 16.0 PERIOD, s Figure 12. Annual wave period distributions, 1985 49. Temporal variation. Temporal height and period trends for Gages 625 and 630 are shown in Figures 13 and 14, respectively, and are con- sistent with those for Gages 640 and 645. Wave heights tended to be above the annual mean during the winter months, dropping below the annual mean by the 333) HEIGHT, m PERIOD, SEC bw ware weeaewn~st oe X EXTREME OQ MEAN [| +1 STANDARD DEVIATION J oF M AM J J A S O N OD J-MA-JJ-SO-D 85 80-84 TIME a. Wave height JF MAM J J A S O N OD J-MA-J J-SO-D 85 80-84 TIME b. Wave period Figure 13. Wave statistics for Gage 625, 1985 34 X EXTREME © MEAN x | +1 STANDARD DEVIATION Ee = o = 5 x x | ee | 4 voy tg 0 J oF MAM J J A S O N OD J-MA-JJ-SO-D 85 80-84 TIME a. Wave height 7 16 15 14 13 12 © i bad ” 10 a S a = we ow fF wens @ @ JF MAM JS J A S O N OD J-MA-JJ-SO-D 85 80-84 TIME b. Wave period Figure 14. Wave statistics for Gage 630, 1985 35 end of spring and start of summer and then increasing to the highest values during autumn. Wave periods were less consistent; however, there was a ten- dency for lower mean periods during winter and spring and higher periods dur- ing summer and autumn. 50. Although the wave height and period distributions for each gage differed, seasonal tendencies were similar to those shown for Gage 625 in Fig- ures 15 and 16. Over 6.2 percent of the waves during October through December 5.0 JAN-MAR 85 ee APR-JUN 85 4.0 evceccces 3.0 DO ewes howe hh ae HEIGHT, m 1.0 0.0 o- 10 ' 10° 10 10° PERCENT GREATER THAN INDICATED Figure 15. Seasonal wave height distributions for Gage 625, 1985 exceeded 2 m, 2 percent during January through March, 1.4 percent during April through June, and only 0.56 percent during July through September. Wave peri- ods of 10, 12, and 14 sec or longer tended to occur most frequently during July through December, while periods of 8 sec were measured over 25 percent of the time during January through June. 51. The distribution of wave directions for the year, based on daily visual observations (Figure 17), revealed that waves approached the pier from the south side 60 percent of the time. Seasonal distributions of the wave directions indicate approximately an even split between north and south for January through March, while approximately 70 percent of the waves approached from the south during April through September. During October through 36 oe JAN-MAR 85 APR-JUN 85 JUL-SEP 85 be ui 25 OCT-DEC 85 S p = ) oe j a 20 s S) § rs) ) rs) § Oo 15 y rs} aN, TL a a > ae AK © 10 f NS 2 ] r) r ry Sy 6S yy = Ni a aN tl Qs VENG oc NS Y cs yr ) ) % NS ) ENS 0 Nd d 6 ah 1.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 12.0 14.0 16.0 PERIOD, s Figure 16. Seasonal wave period distributions for Gage 625, 1985 December 53 percent were from the south, 5 percent shore normal, and 42 per- cent from the north. Present versus past years 52. In general, wave heights during the year were lower than those dur- ing past years. However, the highest wave conditions, to date, were measured during Hurricane Gloria on 27 September when the Ae exceeded 6.1 m (Gage 630), with an associated wave period over 14 sec. The annual distribu- tions for Gage 625 are shown in Figure 18. Heights over 2 m occurred almost 4 percent less frequently during 1985 primarily because of a very mild winter, as shown in Figure 19. With the exception of fewer 10-sec and more 8-sec periods, wave periods were nearly identical (Figure 20). 53. Wave directions, on the other hand, were somewhat different from those of other years, as emphasized by Table 6 and Figure 17. Table 6 shows the resultant (vector averaged) wave height and direction. As can be seen the annual direction is normal to the pier (oriented at 70 deg relative to true north) during 1985, while there has been more of a northerly tendency during prior years. With the exception of September, wave directions were predomi- nantly from the south from March through October 1985. SY 1985 HEIGHT 0.7 m DIRECTION 70 deg 135.0 202.5 180.097" Ss 1980-1984 HEIGHT 0.8 m DIRECTION 68 deg HEIGHT, m Oo - id va > oi Sik Soahe nests 0.20 .40 .60 .80 1.00 FREQUENCY,% Figure 17. Comparison of annual wave roses, 1985 versus 1980-1984 38 5.0 80-84 4.0 EAs) 1 Nye alice arn GN * Wii eeree a TS=8 Oo Lj 2.0 ae 1.0 Pall a 1 0 1 10 10 10 10 10° PERCENT GREATER THAN INDICATED Figure 18. Comparison of annual wave height distributions for Gage 625 5.0 ___ JAN-MAR 80-84 ae JAN-MAR 85 4.0 Engrs _ ag Oo Lj 2.0 = = Bere 1.0 0.0 10° 10° 10° 10 10° PERCENT GREATER THAN INDICATED Figure 19. Comparison of January through March wave height distributions for Gage 625 39 30 25 x4 20 v, O ? oO O ©, or \/ 2 <6) s 13 \/ oO O \/ Q g 0 eo, x 8 \/ ©: ‘as 8 S65 \/ a8 ox \? 2 NAIAIAIIUSS ef O \7 cS OX O “9: 2 OH 2°, ro". 2 ~~ OX 08 °, \/ oO O > 0. @. OOS z eS \/ O . Q FREQUENCY OF OCCURRENCE, % > \/ @: S O © Q ‘a 5 \/ WS SSS 250 xX ©. © \/ 8 KNSSSSANSSA KX is WAIN iS Rs 2, ox \/ KS ‘oe i (=) 16.0 10 3.0 40 5.0 60 7.0 8.0 9.0 10.0 12.0 14. PERIOD, s Figure 20. Comparison of annual wave period distributions for Gage 625 All years 54. The 6 years of data from 1980 through 1985 provide the most com- plete description of the wave climate at the FRF. Annual wave height distri- butions for all of the gages are presented in Figure 21. Gage 640 is a new installation this year. It is located at approximately the seaward extent of the breaker zone. Only 1 year of data is available from it, however. Off- shore at Gage 630, heights can be expected to exceed 2 m over 8 percent of the time, 3 m about 1.2 percent of the time, and to occasionally exceed 4m. At the seaward end of the pier (Gage 625), heights can be expected to exceed 2 m about 5.7 percent of the time and 3 m less than | percent. Seasonal height variation is summarized by examining data for Gage 625. Mean seasonal heights are near 1 m during the winter and autumn and near 0.7 m during spring and summer (Figure 22). During January through March and October through December heights can be expected to exceed 3 m approximately 1 percent of the time. During April through June the heights exceed 2 m approximately 1.2 percent of the time, while during July through September they exceed the same height over 2.1 percent (Figure 23). 55. Seasonal wave period variation for all years of data combined are 40 Table 6 Resultant Wave Height and Directions a 1985 1980-1984 1980-1985 Direction Direction Direction Month Height, m deg True N Height, m deg True N Height, m deg True N Annual Jan-Dec OR 70 0.8 68 0.8 68 Seasonal Jan-Mar 0.8 66 Lo@ 63 0.9 64 Apr-Jun 0.6 79 0.6 78 0.6 78 Jul-Sep 0.6 73) 0.6 72 0.6 72 Oct-Dec 0.8 65 1.0 63 0.9 64 Monthly Jan 0.7 58 1.0 55 0.9 56 Feb 0.8 69 1.0 66 1.0 67 Mar 0.8 71 0.9 67 0.9 67 Apr 0.7 85 0.7 72 0.7 75 May 0.6 76 0.7 78 0.6 78 Jun 0.4 74 0.6 84 0.5 83 Jul 0.5 79 0.4 80 0.4 80 Aug 0.7 76 0.6 72 0.6 73 Sep 0.7 66 0.9 68 0.8 68 Oct 0.9 80 ey 66 1.0 68 Nov 0.9 68 0.9 60 0.9 61 Dec 0.6 43 0.9 64 0.8 61 shown in Figure 22. The histogram of seasonal wave period in Figure 24 shows periods of 10 to 11.9 sec occurring most often and periods of 12 sec or longer occurring most often during winter and autumn. 56. The tendency for higher waves to be associated with longer wave periods is shown in Table 7. These joint distributions of wave height and period for Gages 630 and 625 are based on over 7,300 observations each. The values presented can be converted to percent by dividing by 100. 57. Annual and seasonal wave directions are shown in Figure 25. Waves can be expected to approach from the north side of the pier 52 percent of the time, within 1 deg of shore normal 8 percent, and from the south 40 percent. However, when the wave heights exceed 2 m at Gage 625, 80 percent of the time the approach will be from the north side, 7 percent shore normal, and 13 per- cent from the south. 41 HEIGHT, m 5.0 4.0 3.0 2.0 1.0 0.0 10° —_._ GAGE 625 10° 10° 10 PERCENT GREATER THAN INDICATED Figure 21. Annual wave height distributions, 1980-1985 42 HEIGHT, m PERIOD, SEC we we @weewrt ee X EXTREME ©O MEAN ] +1 STANDARD DEVIATION J oF M Aw J J A S O ND JM A-J J-S 0-D80-85 TIME a. Wave height J oF M AWM J J A S O N_ OD J-M A-J J-S 0-D80-85 TIME b. Wave period Figure 22. Wave statistics for Gage 625, 1980-1985 43 —__ JAN-MAR 80-85 ----. APR-JUN 80-85 2 My . JUL-SEP 80-85 _-— OCT-DEC 80-85 2S ~+ S re) w 6 (=) N LHOISH oO = 2 ° 10° 10 10 ' PERCENT GREATER THAN INDICATED 10° Seasonal wave height distribution for Figure 23. Gage 625, 1980-1985 JAN-MAR 80-85 APR-JUN 80-85 JUL-SEP 80-85 OCT-DEC 80-85 n {-) Cy) (=) Cr) N (| C2 = % “JONIYANDIO JO AONANDIAYA 10 3.0 40 5.0 6.0 7.0 8.0 9.0 10.0 12.0 14.0 16.0 PERIOD, 8 Seasonal wave period distributions for Figure 24. Gage 625, 1980-1985 44 Table 7 Joint Distribution of Wave Height Versus Period, 1980-1985 HEIGHT (METERS) 1. 0- 2.9 0.00 - 0.49 22 0.50 - 0.99 30 1.00 - 1.49 1.50 - 1.99 2.00 - 2.49 2.50 - 2.99 3.00 - 3.49 3.50 - 3.99 4.00 - 4.49 4.50 - 4.99 5.00 - GREATER TOTAL 52 HEIGHT (METERS) 1.0- 2.9 0.00 - 0.49 11 0.50 - 0.99 4 1.00 - 1.49 1.50 - 1.99 2.00 - 2.49 2.50 - 2.99 3.00 - 3.49 3.50 - 3.99 4.00 - 4.49 4.50 - 4.99 5.00 - GREATER TOTAL 15 TOROS asl, S) 10. O- he 12. O- 1359 1250-8147 0— 16" 0- 13.9 15.9 LONGER 218 238 1 34 S1 20 14.6- 16 0- 15.9 LONGER 153 229 2 157 96 49 28 11 QNuGgu 729 43 19 45 177 4 8 3 3 Gage 630 ANNUAL PERCENT OCCURRENCE(X100) OF HEIGHT AND PERIOD PERIOD(SECONDS) 9,02 (0 BO &O> ZO Ge FG 19 49 G9 GO ZAP BO 29 15 27 458 96 117 271 320 114 264 452 589 510 658 497 7 102 344 469 292 209 198 7 118 281 1239 66 62 % 7 CG 3 G8 i FO 2 1 ig 1 9 1 136 400 998 1516 1164 1281 1363 Gage 625 ANNUAL PERCENT OCCURRENCE(X100) OF HEIGHT AND PERIOD PERIOD(SECONDS) “02 405 &@> Gi 76> E65 Oo XO AO GOVAD BO oO o.o 24 38 Si 112 205 345 388 70 242 372 493 442 «593 713 1 62 273 409 259 173~«1178 y 142 9G TS GS in -igomemnae ose vay A A Ee) by ; 4 4 95 345 759 1244 1101 1217 1413 45 TOTAL TOTAL 202.5 180.010” 5 1980-1985 HEIGHT 0.8 m DIRECTION 68 deg N 0.0 22,5 45.0 9 Ve 67.5 Se Va 90.0E \ @ g WY 112.5 135.0 180.0'97-5 JAN-MAR HEIGHT 0.9 m DIRECTION 64 deg 67.5 =? 4 90.0E \e a g 202.8 180.0178 APR-JUN HEIGHT 0.6 m DIRECTION 78 deg HEIGHT, m fH (YT) fp oe eo oe 0°0 0 .20 40 .60 .60 1.00 FREQUENCY,% 90.0E ie d @ “a Ne 112.5 \ 135.0 202.5 3180.07 = JUL—SEP HEIGHT 0.6 m DIRECTION 72 deg N 0.0 995 45.0 a9 gO S75 > = 90.0E @ as Wy 112.5 135.0 180.0975 OCT-DEC HEIGHT 0.9 m DIRECTION 64 deg Figure 25. Annual and seasonal wave roses, 1980-1985 46 PART IV: CURRENTS 58. Surface current speed and direction at the FRF are influenced by winds, waves, and, indirectly, by the bottom topography. The extent of the respective influence varies daily. However, winds tend to dominate the currents at the seaward end of the pier, while waves dominate within the surf zone. Observations 59. Near 0700 hours daily observations of surface current speed and direction were made at (a) the seaward end of the pier, (b) the midsurf position on the pier, and (c) 10 to 15 m from the beach 500 m updrift of the pier. Surface currents were determined by observing the movement of dye on the water surface. Results Present year 60. Spatial variation. Figure 26 shows the daily 1985 measurements at the beach, pier midsurf, and pier end locations. Since the relative influ- ences of the winds and waves vary with position from shore, the current speeds and, to some extent, direction vary at the beach, midsurf, and pier end loca- tions. Magnitudes generally are largest at the midsurf location and lowest at the end of the pier. Annual mean currents (Table 8 and Figure 27) were directed southward at the beach location and near zero at the pier end and midsurf locations. There was a strong tendency for more northward directed currents at the midsurf locations than at the beach from April through November. 61. Temporal variation. During January through March the currents were most often southward, though frequent reversals were observed at the seaward end of the pier during March. For April there were more northward currents at the midsurf than at the beach. May and June had frequent reversals, and the monthly means were low. During August, October, and November there were pre- dominantly northward currents at the midsurf while at the beach there were frequent reversals. Currents were directed southward during December. 47 CURRENT SPEED, cm/s PIER END PIER SURF u I = —_ ao 3) ] [=) o = i o ua a (=) eo (=) (=) —_ wo (eo) 200 BEACH (500m UP DRIFT) JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTH Figure 26. Daily surface currents, 1985 48 Table 8 Annual and Monthly Longshore Surface Currents at the FRF* Beach, cm/sec Pier Midsurf, cm/sec Pier End, cm/sec 1980- 1980- 1981- 1981- 1980- 1980- Month 1985 1984 1985 1985 1984 1985 1985 1984 1985 Jan 23 17 17 33 21 23 19 23 22 Feb U/ 10 11 12 5 6 20 22 17 Mar -1 16 14 14 11 12 15 17 14 Apr 3 4 5) -7 -2 -1 17 WAL 8 May 8 -4 -2 -2 -10 -8 3 8 8 Jun -7 -7 -6 2 -16 -11 4 6 1 July -14 -16 -12 -4 -23 -19 4 3 0 Aug -18 -10 -6 -25 -12 -15 7 11 6 Sep 5 2 4 33 0 2 US, ii Oct -2 5 7 -19 12 5 3 13 10 Nov -l 72 10 -17 14 7 -2 14 12 Dec 16 8 8 D5) 16 16 9 ial 12 Annual 1 3 4 1 1 1 10 13 10 * + = southward; - = northward. -50.0 1985 NORTH LOCATION MEAN, cm/s -40.0 x PIER END 9.6 o PIER SURF 0.7 -30.0 so BEACH 1.5 CURRENT SPEED, cm/s JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTH Figure 27. Monthly mean currents, 1985 49 Present versus past years 62. Im previous years, the currents measured at the beach and midsurf locations were directed southward during the cold months and northward from June through August with frequent reversals during the transition months, May and September. At the seaward end of the pier, the currents were predomi- nantly southward all year long. In 1985, the monthly mean currents were pre- dominantly southward or highly mixed at the pier end location, as can be seen in Figure 28. At the midsurf location there were frequent reversals during June through August and predominantly northward directed currents during November and December (Figure 29). The currents were highly mixed during March, October, and November at the beach location (Figure 30). The annual mean at the midsurf location was approximately equal to that for previous years, while at the other locations the means reflect the higher frequencies of southward currents at the beach and northward currents at the seaward end of the pier. All years 63. Considering all of the years combined (Figure 31), currents were directed southward most often during January through March and October through December and northward most often during June through August. While the beach and midsurf locations show the currents tended toward both directions, at the pier end the overall monthly means were southward. 50 CURRENT SPEED, cm/s CURRENT SPEED, cm/s PIER END -50.0 NORTH YEAR MEAN, cm/s -40.0 o 85 9.6 12.0 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTH Figure 28. Comparison of surface currents at the pier end -50.0 PIER SURF NORTH YEAR MEAN, cm/s -40.0 ° 85 07 x 80-84 1.0 -30.0 R -20.0 Ne TaN pak en i ne -10.0 va yi xe SOUTH 50.0 zw JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTH Figure 29. Comparison of surface currents at the midsurf 51 CURRENT SPEED, cm/s CURRENT SPEED, cm/s BEACH NORTH YEAR. MEAN, cm/s o 85 1.5 x 81-84 3.0 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTH Figure 30. Comparison of surface currents at the beach 80-85 NORTH LOCATION MEAN, cm/s x PIER END 10.0 o PIER SURF 1.0 o BEACH 4.0 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTH Figure 31. Mean surface currents, 1980-1985 52 PART V: TIDES AND WATER LEVELS Measurement Instrument 64. Water level data were obtained from a NOAA/NOS control tide station (sta 865-1370) located at the seaward end of the research pier (Figure 2) by using a Leupold and Stevens, Inc. (Beaverton, Oreg.) digital tide gage. This analog-to-digital recorder is a float-activated, negator-spring, counterpoised instrument that mechanically converts the vertical motion of a float into a coded, punched paper tape record. The below-deck installation at pier sta 19+60 consisted of a 30.5-cm-diam stilling well with a 2.5-cm orifice and a 21.6-cm-diam float. 65. The tide gage was checked daily for proper operation of the punch mechanism and for accuracy of the time and water level information. The accu- racy was determined by comparing the gage level reading with a level read from a reference electric tape gage. Once a week, a heavy metal rod was lowered down the stilling well and through the orifice to ensure free flow of water into the well. During the summer months, when biological growth was most se- vere, divers inspected and cleaned the orifice opening as required. 66. The tide station was inspected quarterly by a NOAA/NOS tide field group. Tide gage elevation was checked using existing NOS control positions, and the equipment was checked and adjusted as needed. NOS and FRF personnel also reviewed procedures for tending the gage and handling the data. Any spe- cific comments on the previous months of data were discussed to ensure data accuracy. 67. Digital paper tape records of tide heights taken every 6 min were analyzed by the Tides Analysis Branch of NOS. An interpreter created a digi- tal magnetic computer tape from the punch paper tape which was then processed on a large computer. First, a listing of the instantaneous tidal height val- ues was created for visual inspection. If errors were encountered, a computer program was used to fill in or recreate bad or missing data using correct val- ues form the nearest NOS tide station and accounting for known time lags and elevation anomalies. The data were plotted, and a new listing was generated and rechecked. When the validity of the data had been confirmed, monthly tab- ulations of daily highs and lows, hourly heights (instantaneous height se- lected on the hour), and various extreme and/or mean water level statistics 53) were computed. The monthly or annual mean sea level (MSL) reported is the av- erage of the hourly heights, while the mean tide level (MTL) is midway between mean high water (MHW) and mean low water (MLW) which are the averages of the daily high and low water levels, respectively, relative to NGVD. Results Present year 68. Tide height statistics for 1985 are presented in Table 9. Tides at the FRF are semidiurnal with both daily high and low tides approximately equal. The annual mean range was 96 cm while MSL was 11 cm above NGVD. The highest water level (136 cm) occurred on 14 December during moderate 10 m/sec winds from the north coincident with the monthly spring tide. Present versus past years 69. Figure 32 shows the monthly tide statistics for 1985 and the previ- ous years. Although MSL increased during the first 11 months of the year, the sharp fall in December kept it within 1 cm of the 12-cm average for previous years. Figure 33 compares the distribution of daily high and low water levels and hourly tide heights for the current year versus previous years. Except for the lack of extremely high or low water levels during 1985, the distribu- tions are essentially equivalent. All years 70. Based on the distribution of the tide heights for all years (Fig- ure 34), the tide can be expected to exceed 110 cm for 0.27 percent of the time (24 hr). Likewise, the heights can be expected to be less than -80 cm for 0.22 percent of the time (19 hr). 54 Table 9 1985 Tide Height Statistics* Month Mean Mean Mean Mean or High Tide Sea Low Mean Extreme Year Water Level Level Water Range High Jan 54 8 9 -38 92 98 Feb Dil 1 2 -49 100 100 Mar 48 0 1 -47 95 70 Apr 52 3 4 -45 97 97 May 60 1l 11 -38 98 126 Jun 57 8 8 -41 98 100 Jul 59 10 11 -38 97 111 Aug 63 15 16 -32 95 101 Sep 65 18 18 -30 95 103 Oct 67 20 20 -28 95 106 Nov V2 25 25 -22 94 124 Dec 55 7 8 -41 96 136 1985 59 10 1l -37 96 136 1979- 61 1l 162 -39 100 149 1984 1984 64 16 16 -32 97 147 1983 68 19 19 -30 98 143 1982 58 8 9 -42 99 127 1981 59 8 9 -42 101 149 1980 59 8 8 -43 102 118 1979 60 9 9 -43 103 121 * Measurements are in centimetres. 55 Extreme Low -108 -110 -119 =95) 13 MIN TSW 1 MHW 1 aw H3 cs6l G861-8L61 ‘SOFISTIeIS TeAeT 103eM pue epTI ATYIUOW “ZE eAN3Ty uvaA vs6l £86l c86l L86l O86 6261 8Z26t Odl—- O00lL- o8- 09- OVv- 0X4 OV Wd *79A3971 Y3LVM a/F 09 08 (=) Ol ° cl Ov! 56 WATER LEVEL, cm WATER LEVEL, cm 150 125 100 0.01 0.10 Figure 33. = 1 —~ fl 1 = ee eee eee ee 1.00 10.00 25.00 50.00 75.00 90.00 99.00 99.90 99.99 PERCENT GREATER THAN Comparison of hourly tide heights and daily high and low water level distributions, 1979-1984 versus 1985 150 125 100 -100 —125 1 esol eel Lea oe ee eee (ME papi etna 1 —ii 0.01 0.10 1.00 10.00 25.00 50.00 75.00 90.00 99.00 99.90 99.99 Figure 34. PERCENT GREATER THAN Distribution of hourly tide heights and daily high and low water levels, 1979-1985 57 PART VI: WATER CHARACTERISTICS 71. Results of daily measurements at the seaward end of the FRF pier, surface water temperature, visibility, and density are presented in this sec- tion. The summaries represent single observations made near 0700 EST and, therefore, may not reflect daily average conditions, since such characteris-— tics can change within a 24-hr period. Large temperature variations were com- mon when there were large differences between the air and water temperature and variations in wind direction. From past experience, persistent onshore winds piled up warm surface water along the shoreline, while offshore winds caused colder bottom water to circulate up resulting in low temperatures. Temperature Present year 72. Daily sea surface water temperatures (Figure 35) were measured with a NOS bucket and thermometer. Monthly mean temperatures (Table 10) varied with the air temperatures (see Table 2) with approximately a 1l-month lag. 30 _ = N N (2) (2) (2) Co] TEMPERATURE, deg c on 0 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 1985 MONTH Figure 35. Daily sea surface water temperatures, 1985 58 Table 10 Mean Surface Water Characteristics Temperature, °C Visibility, m Density, afin 1980- 1980- 1980- 1980- 1980- 1980- Month 1985 1984 1985 1985 1984 1985 1985 1984 1985 Jan 7.0 5.0 5.4 oe 12 2 1.0255 1.0238 1.0241 Feb 4.3 4.6 4.5 D2 15 1.6 1.0248 O23 /een le O239 Mar 7.9 6.3 6.6 345) 1.4 od 1.0245 160233 602335) Apr 12.6 10.5 10.8 7 oIs) 2.0 Deep 1.0241 O23 lenO233 May 17.0 14.8 ISH 2.6 2th Dates 1.0240 IFO23 0M 10232 Jun 19.4 19.4 19.4 4.0 3.6 3.6 1.0235 LoOAUS 6 @2LY) Jul Dd) 53} DNS) 21.4 363) 357 3.6 1.0227 WeOZLY 1 O2ZI1 Aug 24.4 23.0 23.3 72. Uf 3.0 2.9 1.0216 1.0207 1.0208 Sep Doll 22.6 2G) 58) 2.6 Ne 2.0 1.0213 LeO213 U O2ZU3} Oct 21.4 18.8 19.2 2.6 Noll 1.4 1.0208 1.0222 1.0219 Nov od 14.0 14.6 eZ 0.9 0.9 1.0221 1.0235 1.0232 Dec 11.3 10.0 10.2 3} 1.1 oil 1.0232 1.0240 1.0238 Annual N36 7 14.2 14.4 235 2.0 Do il 1.0232 1.0227 1.0228 Present versus past years 73. In general, the temperatures were warmer during 1985 than in prior years. With the exception of February, June, and September, monthly means (see Figure 36) were consistently over 1 deg warmer resulting in an annual difference of 1.5° C. All years 74, The distribution of surface water temperatures for all years com- bined is shown in Figure 37. Temperatures in excess of 25° C can be expected almost 5 percent of the time (or 18 days per year), while temperatures below 4° C can be expected 21 days per year. wy Visibility 75. Visibility in coastal nearshore waters depends on the amount of salts, soluble organic material, detritus, living organisms, and inorganic particles in the water. These dissolved and suspended materials change the absorption and attenuation characteristics of the water which vary daily and yearly. 59 WATER TEMPERATURE, deg c TEMPERATURE, deg c JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTH Comparison of mean surface water temperatures Figure 36. 30 25 20 15 10 5 0.01 0.10 Figure 37. 1.00 10.00 25.00 50.00 75.00 90.00 99.00 99.90 99.99 PERCENT GREATER THAN Distribution of surface water temperatures, 1980-1985 60 76. Visibility was measured with a 0.3-m—diam secci disk and, similar to water temperature, variation was related to onshore and offshore winds. Onshore winds moved warm clear surface water toward shore, while offshore winds brought up colder bottom water with large concentrations of suspended matter. Present year 77. Figure 38 presents the surface visibility values for the year. Large variations were common, and visibility less than 1 m was expected in any month. 10 9 8 ; 7 ’ ‘ 6 a PRE 8 «5 . VISIBILITY, m : _ fo) JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 1985 MONTH Figure 38. Daily sea surface water visibility, 1985 Present versus past years 78. In general, visibility was higher than in prior years. In particu- lar, during October the monthly mean was 2.7 m, over 1.5 m higher than the average for past Octobers (Figure 39). The annual mean was 0.34 m above that during prior years (Table 10). All years 79. Throughout the year the visibility averages over 2 m with an asso- ciated 1.l-m standard deviation (Table 10). During June and July the visibil- ity was over 3.6 m (standard deviation over 1.5 m), while during November the average is under 1 m, and the deviation is only 0.5 m. Figure 40 shows the 61 VISIBILITY, m 5.0 YEAR. MEAN, m o 85 2.3 x 80-84 2.0 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTH Figure 39. Comparison of mean surface water visibility 10 9 8 7 E e¢ z= a 5 a a > 4 3 2 1 8 0.01 0.10 1.00 10.00 25.00 50.00 75.00 90.00 99.00 99.90 99.99 PERCENT GREATER THAN Figure 40. Distribution of surface water visibility, 1980-1985 62 distribution of visibility for all years combined. Approximately 5 percent of the time the visibility can be expected to exceed 5 m, while over 30 percent of the time it is less than 1 mn. Density Present year 80. Daily surface density values presented in Figure 41 were measured with a hydrometer. Density, similar to temperature and visibility, shows con- siderable scatter. DENSITY, g/cm**3 1.011 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT ‘NOV DEC 1985 MONTH Figure 41. Daily sea surface water density, 1985 Present versus past years 81. In comparison to prior years, monthly mean density was higher before September and lower from October through December (Figure 42). All years 82. The annual mean density was 1.0228 alftsae with an associated stan- dard deviation of 0.002 afian (see Table 10). The distribution of density for all years combined is presented in Figure 43. 63 DENSITY, g/em**3 1.029 YEAR MEAN, g/cm**3 o 85 1.0 x 80-84 1.0 DENSITY, g/cc JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTH Figure 42. Comparison of mean sea surface water density 0.01 0.10 1.00 10.00 25.00 50.00 75.00 90.00 99.00 99.90 99.99 PERCENT GREATER THAN Figure 43. Distribution of surface water density, 1981-1985 64 PART VII: SURVEYS 83. Waves and currents interacting with bottom sediments produce changes in the beach and nearshore bathymetry. These changes can occur very rapidly in response to storms or slowly as a result of persistent but less forceful seasonal variations in wave and current conditions. 84. Nearshore bathymetry at the FRF is characterized by regular shore- parallel contours, a moderate slope, and a barred surf zone; usually an outer storm bar in water depths of about 4.5 m and an inner bar in water depths be- tween 1.0 and 2.0 m. This pattern is interrupted in the immediate vicinity of the pier where a trough runs under much of the pier, ending in a scour hole at the pier end where depths are up to 3.0 m greater than the adjacent bottom. 85. The research pier introduces a perturbation in bathymetry (Fig- ure 44) in the form of a permanent trough under the pier, apparently a result of the interaction of waves and currents with the pilings. The trough deepens under the seaward end of the pier and varies in shape and depth with changing wave and current conditions. The pier's effect on shore-parallel contours oc- curs as far as 300 m away, and the shoreline may be affected up to 350 m from the pier (Miller, Birkemeier, and DeWall 1983). 86. To document the temporal and spatial variability in bathymetry, surveys were conducted approximately monthly of an area extending 600 m north and south of the pier and approximately 950 m offshore. 87. Profiles were obtained monthly and after storms by using the Coastal Research Amphibious Buggy (CRAB), a 10.7-m-tall amphibious tripod, and a Zeiss Elta-2 total station surveying system described by Birkemeier and Mason (1984). The profile locations are shown on each figure in Appendix A. The survey accuracy was about +3 cm horizontally and vertically. Monthly soundings along both sides of the FRF pier were collected by lowering a weighted measuring tape to the bottom and recording the distance below the pier deck. Soundings were taken midway between the pier pilings to minimize errors caused by scour near the pilings. 88. The pier, beach, nearshore, and offshore data were reduced to posi- tion (X,Y) and depth (Z) triplets relative to established monumentation and NGVD, respectively. The data were listed, and a display of the profiles (i.e. distance along the range versus elevation) were generated for inspection. After the data were edited, another set of routines was used to compute 65 FRF BATHYMETRY 14 FEB 85 Figure 44. Permanent trough under the FRF pier (14 February 1985) contour diagrams of the bottom topography and time sequences of bottom eleva- tions at selected locations along the pier. Bottom Elevation Histories 89. Useful for interpretation of the wave data from Gages 645 and 625 located under the pier, a history of the bottom elevations is presented at their respective pier stations, sta 7+80 (238 m) and sta 19+00 (579 m). Histories at intermediate locations, 323 and 433 m, are also included (Fig- ure 45). Variations of elevation under the pier are caused by natural pro- cesses (such as profile changes caused by bar movement) as well as scour 66 Oo DISTANCE (m) I —_ -2 Se F=3 : ‘ : 3) ASKS} Q —4 = a —— o -6 : 3 S2S GQ =7, ' : : S|) ZESS) -8 9 579 -10 eke Mime Ac Me de ale GAYS) Or Nw DB 1985 MONTH Figure 45. Time-history of bottom elevations at selected locations under the FRF pier resulting from the interaction of the pier piles with waves and currents. Throughout the year the scour hole at the seaward end of the pier varied ap- proximately 0.9 m, which is relatively low in comparison to some prior years when the variation was observed to exceed 2 m in a year. 90. After an initial deepening of 0.8 m in February, at the 238-m dis- tance, sediment slowly accumulated until September when it was again near -2.4 m. Hurricane Gloria in September caused 1.4 m of erosion. During this time, 0.8 m of scour was measured at the seaward end of the pier. Bathymetry 91. Contour diagrams created from the data obtained during the bathy- metric surveys are presented in Appendix A; change diagrams showing major areas of erosion and accretion in the survey area are also presented. Profile lines surveyed are indicated on each contour diagram. 67 PART VIII: PHOTOGRAPHY Aerial Photographs 92. Aerial photography was taken quarterly by using a 23-cm aerial mapping camera at a scale of 1:12,000. All coverage was at least 60 percent overlap, with flights flown as closely as possible to low tide between 1000 and 1400 EST with less than 10 percent cloud cover. Table 11 summarizes the available aerial photographs. The flight lines covered are shown in Fig- ure 46. Figure 47 is a sample of the imagery obtained (9 February 1985). Table 11 Aerial Photography Inventory for 1985 THe ””*~=“‘iséS*éSCSME TS OCC~=“‘SCS*‘C AE 9 Feb 2 and 3 Color 15 May 2 and 3 Color 23 Aug 1 and 3 B/W 28 Sep 1 B/W 26 Oct 2 and 3 Color Beach Photographs 93. Daily color slides of the beach were taken using a 35mm camera from the same location on the pier looking north and south (Figure 48). The loca- tion from which each picture was taken, as well as the date, time, and a brief description of the picture, was marked on the slides. 68 —\ 29 RUOEE INLET SCALE 1-:12,000 A CAPE HATTERAS Re FIELD RESEARCH FACILITY Figure 46. Aerial photography flight lines 69 Figure 47. Sample aerial photograph taken 9 February 1985 70 (SS b. South Figure 48. Sample photographs of the FRF beach taken 17 August 1985 Ya PART IX: STORMS 94. This section discusses the details of storms affecting the FRF. As used here, "storms" are defined as times when the wave height parameter Hoe ; equals or exceeds 2.0 m at the seaward end of the FRF pier. Hourly data col- lected during such times are presented in Appendix B. Sample spectra from the Baylor gage at the seaward end of the pier are given in Appendix C (Vol- ume II). Pre- and/or poststorm bathymetry diagrams are given in Appendix A. Detailed information on the track of each storm was taken from the NOAA Daily Weather Maps (US Department of Commerce 1984) and the Mariner's Weather Log series (US Department of Commerce 1984, 1985). 95. There were 13 storms during the year: only one for 3 consecutive days, five for 2 days, and seven for a single day. The number of storms dur- ing 1985 was below the annual average of 16 for prior years. A description of these storms is provided below. a. 3-4 January 1985. A cold front extending from New England to the Gulf of Mexico began moving eastward on 2 January and crossed the North Carolina coastline early on 3 January. A low pressure system developed over the Gulf of Mexico and traveled rapidly up the east coast behind the front (Figure Bl). b. 12 February 1985. On 11 February, a frontal wave located slightly east of the Mississippi River produced two low pres-— sure centers over Mobile, Ala. and St. Louis, Mo. By 12 February, the two lows had converged over central Virginia (Figure B2). c. 22-23 March 1985. A low pressure system originating over the Pacific Ocean was located east of northern Florida by 22 March. The storm moved rapidly up the east coast, passing the FRF on the 23rd before proceeding into the Atlantic (Figure B3). d. April 1985. On 14 April, a low pressure system formed 241 km east of Charleston, S.C., and began moving north along the coast. By 0700 EST on the 15th, the low was located directly over Cape Hatteras, N.C., and continued traveling northward throughout the day (Figure B4). On 29 April, a Canadian high produced strong winds at the FRF after pushing a cold front east past the FRF (Figure B5). e. 3 May 1985. Behind a cold front that moved past the FRF, strong winds from a Canadian high pressure system produced the high waves for a short time (Figure B6). £. 2 August 1985. A low pressure system off New England moved south to Cape Hatteras behind a cold front that was pushed offshore by a huge Canadian high pressure system (Figure B7). 2. [Hs 27 September 1985. On the morning of 27 September, Hurricane Gloria passed over the FRF. Although predicted to affect the area with 67+ m/sec winds, the actual path was slightly seaward of the coast, resulting in less than hurricane force winds at the FRF. In addition, Gloria's rapid passage coincided with low tide which minimized her impact. The storm approached Wilmington, N.C., from the southeast, veering to the north late on 26 September. Picking up speed, the storm's eye passed over Cape Hatteras, N.C., at approximately 0130 EST on 27 September with the western edge of the eye passing over the FRF at approximately 0230 EST. Continuing to gain speed, Gloria made landfall at Long Island, N.Y., early that afternoon. Changes to the beach and dune were minimized by the hurricane's rapid passage and the timing of maximum surge (see FRF Preliminary Data Summary for September 1985) near the astronomical low water (Figure B8). October 1985. On 21-22 October, Genesis of an Atlantic low off Cape Hatteras and a relatively stationary high pressure system over New England produced strong winds for days at the FRF (Figure B9). On 31 October, high waves were first generated by strong easterly winds associated with a large high pressure system centered over New England on 1 November. By 2 November, the remnant of Hurricane Juan, which had struck Louisiana, spawned a new storm over Cape Hatteras, N.C. This storm rapidly moved offshore into the Atlantic (Figure B10). 4-5 November 1985. This low pressure system developed on 3 November along a cold front in the Gulf of Mexico. The storm followed a northerly track over the Appalachian Mountains and was located over western North Carolina early on 4 November. Slowly continuing north, the storm was centered over Maryland on 5 November and off the New England coast by the 6th (Figure Bll). December 1985. On 1-2 December a weak low pressure system developed in Georgia on 30 November and quickly moved past the FRF on 1 December (Figure B12). Forming on a stationary front over Florida early on 6 December, this storm rapidly moved northeast into the Atlantic well off the North Carolina coast on the morning of the same day (Figure B13). 73 REFERENCES Birkemeier, W. A., and Mason, C. 1984. "The CRAB: A Unique Nearshore Sur- veying Vehicle," Journal of Surveying Engineering, American Society of Civil Engineers, Vol 110, No. 1. Field Research Facility. 1985 (Jan-Dec). "Preliminary Data Summary," Monthly Series, Coastal Engineering Research Center, US Army Engineer Waterways Exper-— iment Station, Vicksburg, Miss. Grogg, W. E., Jr. 1986. “Calibration and Stability Characteristics of the Baylor Staff Wave Gage," Miscellaneous Paper CERC-86-7, US Army Engineer Water- ways Experiment Station, Vicksburg, Miss. Harris, D. L. 1974. "Finite Spectrum Analyses of Wave Records," Proceedings, International Symposium on Ocean Wave Measurement and Analysis, New Orleans, La., pp 207-124. Miller, H. C. 1980. "Instrumentation at CERC's Field Research Facility, Duck, North Carolina," CERC Miscellaneous Report 80-8, US Army Engineer Water- ways Experiment Station, Vicksburg, Miss. . 1982. "“CERC Field Research Facility Environmental Data Summary, 1977-79," CERC Miscellaneous Report 82-16, US Army Engineer Waterways Experi-— ment Station, Vicksburg, Miss. . 1984. “Annual Data Summary for 1980, CERC Field Research Facil- ity," Technical Report CERC 84-1, US Army Engineer Waterways Experiment Sta- tion, Vicksburg, Miss. . 1985. “Annual Data Summary for 1981, CERC Field Research Facil- ity," Technical Report CERC 85-3, US Army Engineer Waterways Experiment Sta- tion, Vicksburg, Miss. . 1986a. “Annual Data Summary for 1982, CERC Field Research Facil- ity," Technical Report CERC 86-5, US Army Engineer Waterways Experiment Sta- tion, Vicksburg, Miss. . 1986b. “Annual Data Summary for 1983, CERC Field Research Facil- ity," Technical Report CERC 86-9, US Army Engineer Waterways Experiment Sta- tion, Vicksburg, Miss. - 1986c. “Annual Data Summary for 1984, CERC Field Research Facil- ity," Technical Report CERC 86-11, US Army Engineer Waterways Experiment Sta- tion, Vicksburg, Miss. Matiilere, tle Coo wWaudkameder, Wo Ao, aime! Datel, Ao wo I983, MmiceeeE Oi ne CERC Research Pier on Nearshore Processes," Coastal Structures '83, American Society Of Civil Engineers, Arlington, Va., pp 769-784. Thompson, E. F. 1977. "Wave Climate at Selected Locations Along US Coasts," CERC Technical Report 77-1, US Army Engineer Waterways Experiment Station, Vicksburg, Miss. US Department of Commerce. 1984-1985. ''Mariner's Weather Log," Vols 29 and 30, Washington, D.C. US Department of Commerce. 1984. ''Daily Weather Maps,'' Weekly Series, Washington, D.C. 74 APPENDIX A: SURVEY DATA 1. Contour diagrams constructed from the bathymetric survey data are presented in this appendix. The profile lines surveyed are identified on each diagram. Contours are in half meters referenced to National Geodetic Vertical Datum (NGVD). The distance offshore is referenced to the Field Research Facility (FRF) monumentation baseline behind the dune. 2. Change in FRF bathymetry diagrams constructed by contouring the dif- ference between two contour diagrams are also presented with contour intervals of 0.25 m. Hatched areas show general areas of erosion. Other areas cor- respond to areas of accretion. Although these change diagrams are based on considerable interpolation of the original survey data, they do facilitate comparison of the contour diagrams. Al (uss) oop Os @o O88 OO oc 08 001 (W) 39NULSIG 14 February bathymetry ool! 000} O05 008 0% GOS 00 oo om ce Of Oo «Gol- (Md) JONULS1O 0°93 Figure Al. DISTANCE (M) 23 April bathymetry Figure A2. A2 OISTANCE (FM) 100060 sii 650 e 0 DISTANCE (HM) Figure A3. 14 February to 23 April change diagram OISTANCE (HM) a eo DISTANCE (mM) Figure A4. 15 July bathymetry A3 -m m& of cs o> Ox ox oD (tH) JONWLS10 DISTANCE (fA) 23 April to 15 July Figure A5. change diagram 21 August bathymetry Figure A6. A4 OISTANCE (Ff) Ce a a a a a) 0 0 C=") OISTANCE (Ff) Figure A7. 15 July to 21 August change diagram a RRAAVRELR BE OISTANCE, 4 10 iii C8) eo DISTANCE, A Figure A8. 28 September bathymetry A5 R- Se Ags DISTANCE, A 21 August to 28 September change diagram Figure A9. TRRASBRREBR P a) Se ee Se se me set ool) ogi «00S ki Cia W “JONYLSIO 19 December bathymetry Figure Al0. A6 4D DISTANCE, 28 September to 19 December change diagram Figure All. A7 APPENDIX B: STORM DATA 1. Whenever the wave height Hie exceeded 2 m at the seaward end of the Field Research Facility (FRF) pier, data were collected hourly. Available data for the 13 storms (reported in Part IX of the main text) are presented in Figures B1-B13. Atmospheric Pressure 2. Reported in millibars, atmospheric pressure data are useful for doc- umenting the type of storm, the passage of fronts, and the intensity of the atmospheric pressure system. Wind Speed and Direction 3. Local winds are generally responsible for the wave conditions at the FRF. Wind speed is reported in metres per second. 4. Wind direction, referenced to true (star) north, indicates the directions from which the winds are blowing, e.g., winds blowing from west to east are referred to as having an angle of 270 deg. Wave Direction 5. Referenced to true (star) north, the wave direction measurements are taken at the seaward end of the FRF pier. The pier axis (considered perpen- dicular to the beach at the FRF) is oriented 70 deg east of true north; conse- quently, wave angles greater than 70 deg imply the waves were coming from the south side of the pier. Gage 625 H mo 6. The wave height, measured in metres, was that obtained from the staff wave gage located at the seaward end of the FRF pier. Wave Period 7. The peak spectral wave period in seconds from Gage 625 is reported. Bl Water Levels 8. Reported in centimetres and referenced to the National Geodetic Vertical Datum, the water levels were obtained from the National Ocean Services primary tide sta 865-1370 at the seaward end of the FRF pier. 1050 ATMOSPHERIC PRESSURE, mb GAGE # 616 1010 1000 990 20 WIND SPEED, m/s GAGE # 632 10 Sa Seen IPE MIO Sent a 7 area neee a ENE WAP 0 270 WIND DIRECTION, deg. true N GAGE # 833 160 0 am bo WAVE DIRECTION, deg. true N GAGE # 21 90 enema een eens — 30 -30 3 HMO, m GAGE # 625 2 po ea eg eaten et Dear bh 1 0 20 WAVE PERIOD, s GAGE # 625 10 Pe a aa a ee eS 0 400 WATER LEVEL, c¢ GAGE 0 ee De ee eee ok ea, ae -60 -100 3 4 JANUARY 1985 Figure Bl. Storm data for 3-4 January 1985 B2 ATMOSPHERIC PRESSURE, mb GAGE # 616 WIND SPEED, m/s GAGE # 632 WIND DIRECTION, deg. true N GAGE # 633 WAVE DIRECTION, deg. true N GAGE # 21 eS ee # 625 WAVE PERIOD, 8 GAGE # 625 ea ATER LEVEL, cm GAGE # 1 FEBRUARY 1985 Figure B2. Storm data for 12 February 1985 ATMOSPHERIC PRESSURE, mb GAGE # 616 WIND SPEED, m/s GAGE # 632 WAVE DIRECTION, deg. true N GAGE # 21 WAVE PERIOD, 8 GAGE # 625 a ea OOO es WATER LEVEL, cm GAGE # 1 Fa SOE AE ESS pect m 23 MARCH 1985 Figure B3. Storm data for 22-23 March 1985 B3 24 ATMOSPHERIC PRESSURE, mb GAGE # 616 WIND SPEED, m/s GAGE # 632 WIND DIRECTION, deg. true N WAVE DIRECTION, deg. true ee Sar al HMO, m GAGE # 625 Tat WAVE PERIOD, s GAGE # 625 ida WATER LEVEL, em GAGE # r -50 -100 14 15 16 APRIL 1985 Figure B4. Storm data for 14-15 April 1985 ATMOSPHERIC PRESSURE, mb GAGE # 616 —- WIND SPEED, m/s GAGE # 632 WIND DIRECTION, deg. true N GAGE # 633 9 i eS F WAVE DIRECTION, deg. true N GAGE # 21 9 i 30 -30 3 HMO,m GAGE # 625 2 1 a a i ) za WAVE PERIOD, 8 GAGE # 625 10 3 :—— 0 =>, 100 WATER LEVEL, cm GAGE # 1 0 — —S ——— eet -50 -100 29 30 APRIL 1985 Figure B5. Storm data for 29 April 1985 B4 ATMOSPHERIC PRESSURE, mb GAGE # 616 eee ae WIND SPEED, m/s GAGE # 632 WIND DIRECTION, deg. true N GAGE #633 —~ $9 —_& GAGE # 21 WAVE DIRECTION, deg. true N GAGE # 625 a WAVE PERIOD, s GAGE # 625 —_— MAY 1985 Figure B6. Storm data for 3 May 1985 nese ATMOSPHERIC PRESSURE, mb GAGE # 616 1 Ono pe 1000 990 I] 20 WIND SPEED, m/s GAGE # 632 sae WIND DIRECTION, deg. true N GAGE # 633 ——$— i WAVE DIRECTION, deg. true N GAGE # 21 GAGE # 625 pe gg nn tt WAVE PERIOD, 8 GAGE # 625 WATER LEVEL AUGUST 1985 Figure B7. Storm data for 2 August 1985 BS GAGE # 616 ATMOSPHERIC PRESSURE, mb ND SPEED, m/s GAGE # 632 a O,m GAGE # 625 ee ee — WAVE PERIOD, 8 GAGE # 625 TER LEVEL 27 28 SEPTEMBER 1985 Figure B8. Storm data for 27 September 1985 ATMOSPHERIC PRESSURE, mb GAGE # 616 WIND SPEED, m/s GAGE # 632 270 WIND DIRECTION, deg. true N GAGE # 633 180 90 0 WAVE DIRECTION, deg. true N GAGE # 21 90 pS eee ae ee ee Se ee ee ee ea 30 -30 SSS SE EEE] 3 HMO, m GAGE # 625 2 eas en A a Ne 1a aR oe a 1 0 = —_—_-——. — — —. 70 WAVE PERIOD, 8 GAGE # 625 10 sett gc 2 i pe I EL LA, 6 0 See 100 WATER LE m GA # 1 HY Peel le pete ek, See 0 -50 -100 21 22 23 OCTOBER 1985 Figure B9. Storm data for 21-22 October 1985 B6 1030 ATMOSPHERIC PRESSURE, mb GAGE # 616 GAGE # 632 31 1 2 OCTOBER NOVEMBER 1985 Figure B10. Storm data for 31 October through 2 November 1985 1050 ATMOSPHERIC PRESSURE, mb GAGE # 616 YOUR “Th ae ee ee ee 1000 990 = AG a oe a ee el 20 WIND SPEED, m/s GAGE # 632 WIND DIRECTION, deg. true N GAGE # 633 2 1 20 re za GAGE # 625 | a 0 er ae J : e () —- — -50 -100 es 4 5 6 NOVEMBER 1985 Figure Bll. Storm data for 4-5 November 1985 B7 10350 ATMOSPHERIC PRESSURE, mb GAGE # 516 1010 1000 990 a 20 WIND SPEED, m/s GAGE # 632 10 5 TT 0 = > WIN B-BIRECGH ON, deg. trie N—«—__, _, , ,G/ 270 GAGE # 633 180 90 ) a at Al 3 HMO,m GAGE # 625 2 Pe eee ee ee 1 () Sea ae Les 20 WAVE PERIOD, 8 GAGE # 625 10 a 5 t) a SL SE eee 109 WATER LEVEL, cm GAGE # 1 0 en ee ae a ee -580 -100 1 2 DECEMBER 1985 Figure B12. Storm data for 1 December 1985 WIND SPEED, m/s GAGE # 632 WIND DIRECTION, deg. true N” —-_—_AGE # 633 nh GAGE # 625 —————————E WAVE PERIOD, 8 GAGE # 625 ————————————E VEL, cm GAGE # 1 DECEMBER 1985 Figure B13. Storm data for 7 December 1985 B8 hy ae i in ue \