Technical Report CHL-98-14 May 1998

US Army Corps of Engineers Waterways Experiment Station

Annual Data Summary for 1995 CHL Field Research Facility

Volume |: Main Text and Appendixes A and B

by Michael W. Leffler, Clifford F. Baron, Brian L. Scarborough, Paul R. Hodges, C. Ray Townsend

Approved For Public Release; Distribution Is Unlimited

TA

oO wat No. CHL- Asi Ni

Prepared for Headquarters, U.S. Army Corps of Engineers

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.

The findings of this report are not to be construed as an official Department of the Army position, unless so desig- nated by other authorized documents.

GB) eanres ON RECYCLED PAPER

Technical Report CHL-98-14 May 1998

Annual Data Summary for 1995 CHL Field Research Facility

Volume |: Main Text and Appendixes A and B

by Michael W. Leffler, Clifford F. Baron, Brian L. Scarborough, Paul R. Hodges, C. Ray Townsend

U.S. Army Corps of Engineers Waterways Experiment Station 3909 Halls Ferry Road Vicksburg, MS 39180-6199

HOMO ML

Final report Approved for public release; distribution is unlimited

Prepared for U.S. Army Corps of Engineers Washington, DC 20314-1000

sae

US Army Corps of Engineers Waterways Experiment Station

FOR INFORMATION CONTACT:

PUBLIC AFFAIRS OFFICE

U.S. ARMY ENGINEER

WATERWAYS EXPERIMENT STATION 3909 HALLS FERRY ROAD VICKSBURG, MISSISSIPP! 39180-6199 PHONE: (601) 634-2502

AREA OF SESERVATION : 2.7 sgkm

Waterways Experiment Station Cataloging-in-Publication Data

Annual data summary for 1995 : CHL Field Research Facility / by Michael W. Leffler ... [et al.] ; prepared for U.S. Army Corps of Engineers.

2 v. : ill. ; 28 cm. — (Technical report ; CHL-98-14)

Includes bibliographic references.

v. 1. Main text and appendixes A and B—v. 2. Appendixes C through E.

1. Ocean waves — North Carolina — Duck — Statistics. 2. Water waves — North Carolina — Duck — Statistics. 3. Oceanographic research stations — North Carolina — Duck —Statistics. 4. Oceanography — North Carolina — Duck — Statistics. |. Leffler, Michael W. Il. United States. Army. Corps of Engineers. Ill. U.S. Army Engineer Waterways Experiment Station. IV. Coastal and Hydraulics Laboratory (U.S. Army Engineer Waterways Experiment Station) V. Title: CHL Field Research Facility annual data summary for 1995. VI. Series: Technical report (U.S. Army Engineer Waterways Experiment Station) ; CHL-98-14.

TA7 W34 no.CHL-98-14

Contents

Page

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IREFETENCES ened sree eee coats ovement sais) eee crap emer eee Ap pendixeAcE SULV cys atau y arin lemen ten ea ee an ea eI AppendixgB -aawave mata tom Gauge.O30 00) freien cie reer

Delhy Jel eWel Wo cobb cosde ab eewdoccobatend buss Joint Distributionsyof wipe vand) Tye nes ene crs ieee Cumulative Distributions of Wave Height .............. Peak Spectral Wave Period Distributions ............... Persistence of Wave Heights ...................-.--.- SPECt a rarcr tere acne etre ae cil aroatey sore emtel erteteeie Rome Ricaae aa

Appendixa€:. Wave DatastomGaures Gi ma. mnie

DENI? Jel fil Jo oo oko snus eacoseanososoonDoses Joint, Distributions ote and yee yrs ert cerry eye Cumulative Distributions of Wave Height .............. Peak Spectral Wave Period Distributions ............... Persistence of Wave Heights .............---.-++---- Spectra: ose n ete crecnens Cee eet enna ened cased geen la

1 A limited number of copies of Appendixes C-E (Volume II) were published under separate cover. Copies are available from National Technical Information Service, 5285 Port Royal Road, Springfield, VA 22161.

Appendix) Ds WaveyD ata for Gauge 625i) 4-) ae es eae D1

Db atl yap Ed yarn Tool.) opus suis iG tees epee ake tae ae Ne D1 Joint Distributions of He. and is veer een D1 Cumulative Distributions of Wave Height .............. D1 Peak Spectral Wave Period Distributions ............... D2 JHEPINENES OWEN ISON 258 6cgcabocodecegocabous D2 SPE Cli ah se res 2 arcs eta OeUee oAlee ral ae mae pes erg eae e D2 AppendixgE = Wave Datalfor Gaugelo4l Cannery eeu El Daily re and 8 rai. yaucbestis act ty cos ae epee we is ecnicde Sel E1 Joint Distributions iol ein .an delay lie eerie El Cumulative Distributions of Wave Height .............. El Peak Spectral Wave Period Distributions ............... E2 RersistenceOfaWiaveyELe1onits serie a nea aire E2 SS) BLLELIIE: Vern gn eh BPO ae erm inter se Ad Vda 8 91 a) te al ma E2

SF 298

Preface

This report is the 17th in a series of annual data summaries authorized by Headquarters, U.S. Army Corps of Engineers (HQUSACE), under the Civil Works Research and Development Program, Work Unit 32525, "Field Research Facility Analysis." Funds were provided through the U.S. Army Engineer Waterways Experiment Station (WES), Coastal and Hydraulics Laboratory (CHL), under the program management of Ms. Carolyn M. Holmes. The HQUSACE Technical Monitors were Messrs. John H. Lockhart, Jr., Charles Chesnutt, and Barry W. Holliday.

Data for the report were collected and analyzed at the WES/CHL Field Research Facility (FRF) in Duck, NC. The report was prepared by Mr. Michael W. Leffler, FRF, under the direct supervision of Mr. William A. Birkemeier, Chief, FRF Group, Engineering Development Division (EDD), and Mr. Thomas W. Richardson, Chief, EDD; and under the general supervision of Dr. James R. Houston and Mr. Charles C. Calhoun, Jr., Director and Assistant Director, CHL, respectively. Messrs. Kent K. Hathaway and Paul Hodges assisted with instrumentation. Messrs. Brian L. Scar- borough and C. Raymond Townsend, FRF, with Messrs. Christopher Goshow and Kevin M. Kremkau assisted with data collection. Mr. Clifford F. Baron assisted with data analysis. The National Oceanic and Atmospheric Administration/National Ocean Service maintained the tide gauge and provided statistics for summarization.

At the time of publication of this report, Director of WES was Dr. Robert W. Whalin. Commander was COL Robin R. Cababa, EN.

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.

1 Introduction

Background

The U.S. Army Engineer Waterways Experiment Station, Coastal and Hydraulics Laboratory’s' (CHL), Field Research Facility (FRF), located on 0.7 km? at Duck, NC (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, NC. 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 during severe storms; (b) provide CHL with field experience and data to complement laboratory and analytical studies and numerical models; (c) provide a manned field facility for testing new instrumentation; and (d) serve as a permanent field base of operations for physical and biological studies of the site and adjacent region.

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 duneline 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.

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.

; Formerly the Coastal Engineering Research Center

Chapter 1 Introduction

This report, which summarizes data for 1995, continues a series of reports begun in 1977.

S ATLANTIC OCEAN

Figure 1. FRF location map

Organization of Report

This report is organized into nine chapters and five appendixes. Chapter 1 is an introduction; Chapters 2 through 8 discuss the various data collected during the year; and Chapter 9 describes the storms that oc- curred. Appendix A presents the bathymetric surveys, Appendix B summarizes deepwater wave statistics, and Appendixes C through E (published under separate cover as Volume II) contain summary statistics for other gauges.

In each chapter of this report, the respective instruments used for monitoring the meteorological or oceanographic conditions are briefly

Chapter 1 Introduction

described, along with data collection and analysis procedures and data results. The instruments were interfaced with the primary data acquisition system, a Digital Equipment Corporation (Maynard, MA) VAX-11/750 minicomputer until June 1994 when it was replaced with a Digital Equipment Corporation VAXstation 4000 located in the FRF laboratory building. More detailed explanations of the design and the operation of the instruments may be found in Miller (1980). Readers' comments on the format and usefulness of the data presented are encouraged.

Availability of Data

Table 1 summarizes the available data. In addition to the wave data summaries in the main text, more extensive summaries for each of the wave gauges are provided in Appendixes B through E.

Table 1 1995 Data Availability

Gauge Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Anemometer 932 * * * % # Ok Rk Ok kOe kk ke ek ek ee ke ek ke ek ke ke kkk kek kok koe ee ek Atm Pres. 616 * * * % % eke kk RRR ek kk ee ek eke ek kk ke eee kk kk eke ee ek ek Air Terp 624 8 ek Re RR ke eek ok eee ek kek eke ke kkk ke oe ok ee ee Precip. 604 ee ee ee ke ek kak ee ee ake ok ae ok ee ek eek ede eae eke eek ee eee ek

Waves Waverider GOR RR KKK RRR RRR RR ee ee eR ek 7 ke Pk RRR RR RR Ke

&m Press. WERE RRR RRR KKK KR RR RR Re ee ee ke ek ke ek ek ew kk kk ek ke EOP Press. 625 * ERR KKK KKK KK KAKA RRR RR RR eR RR RR RR RR RR RR KK RR Pier Nshre 641 * * *¥ # ¥ kk wR eR kk RR RR ee ek kk ek ee kk kk ek ke ek ke ke kk kk kk kk kk ee

Currents Pier End KERR KKEKEKEKEKEKE KKK KKE KKK KKK KKK KK KKK KKK KKK KAEKKEK KKK KKK KK KEK

Pier Nrshre KEK KKK KKK KKK KKK KKK KKK KKK KEKE KKK KEK KKK KEKEK KKK KKK KKK KEK KEKE EE Beach keke keke keke KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KK KEK

EOP Tide Gage * *** #4 eee kee RAR RR RR RR RR Re ee RE Re KX K

Water Characteristics Temperature Re KEKE KK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KEK KKK KKK KEKE KEK

Visibility kkk KEK KKK KK KKK KKK KKK KK KKK KKK KK KKK KKK KKK KKK KK KEK KE KK Density KKK KEKKEKKAKAKRKKKKKR KKK KKK KKK KKK KKK KKK Kh kkk KK kK Ke

Bathymetry * * * * * *

Photography Beach

Aerial

kek KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK *

Notes: * Full week of data obtained. / Less than 7 days of data obtained. - No data obtained.

Chapter 1 Introduction

The annual data summary herein summarizes daily observations by month and year to provide basic data for analysis by users. Daily measure- ments and observations have already been reported in a series of monthly Preliminary Data Summaries (FRF 1995). If individual data for the present year are needed, the user can obtain detailed information (as well as the monthly and previous annual reports) from the following address:

USAE Waterways Experiment Station Field Research Facility

1261 Duck Rd.

Kitty Hawk, NC 27949-4472

Much of this data is now also available via the World Wide Web at: http://www.frf.usace.army.mil

Although the data collected at the FRF are designed primarily to support ongoing CHL research, use of the data by others is encouraged. 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

ATTN: 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 CHL or the National Oceanic and Atmospheric Administration (NOAA)/National Ocean Service (NOS) determine whether other relevant data are available. For information regarding the availability of data for all years, contact the FRF at (252) 261-3511. Costs for collecting, copying, and mailing will be borne by the requester.

Chapter 1 Introduction

2 Meteorology

This chapter summarizes the meteorological measurements made during the current year and in combination with all previous years. Meteorological measurements during storms are given in Chapter 9.

Mean air temperature, atmospheric pressure, and wind speed and direction were computed for each data file, which consisted of data sampled two times per second for 34 min every 6 hr beginning at or about 0100, 0700, 1300, and 1900 hr eastern standard time (EST); these hours correspond to the time that the National Weather Service (NWS) creates daily synoptic weather maps. During storms, data recordings were made more frequently. Meteorological data are summarized in Table 2.

Table 2 Meteorological Statistics

Mean Mean Wind Resultants Air Temperature Atmospheric Pres. Precipitation, mm 1995 1980-1995

deg C Mb 1995 1978-1995 Speed Direction Speed Direction Month 1995 19835-1995 _ 1995 1983-1995 Total Mean Maxima Minima m/s deg m/sec deg Jan 7.1 1016.1 1017.8 110 331 Feb 1016.0 1017.3 74 Mar 1018.7 1016.0 106 1015.1 1014.2 90 1014.8 1015.7 79 1015.3 1015.1 91 1016.2 1015.9 96 1015.6 1016.3 111 1017.3 1017.6 82 1017.2 1018.6 82 1018.0 1018.4 1018.6 1019.2

° DS)

== oe 8 8 s 2 6 o oe ee

.

RRWROwMUOUUD

== inv) == NUBRPURRSR nD ONDHOUUNNOUD MI Oe WNW Me OeCWNs oS UEONUUAN OF O NA2NNON20O2-=N ENWOUDOWNW OND

4 9 4 9.

3

26

(5)

22

19 9. 4.

ey © ro)

1016.6 1016.8

Chapter 2 Meteorology

Air Temperature

The FRF enjoys a typical marine climate that moderates the temperature extremes of both summer and winter.

Measurement instruments

A Yellow Springs Instrument Company, Inc. (YSI) (Yellow Springs, OH), electronic temperature probe with analog output interfaced to the FRF's computer was operated beside the NWS's meteorological instrument shelter located 43 m behind the dune (Figure 2). To ensure proper temperature readings,

Pressure Gauge No..111 0.9 km offshore

Baylor Gauge No. 625

ee

B Pressure Gauge No. 641 “ % : Tide Gauge

Sion No. 865-1370

” Waverider Buoy No. 630 6 km offshore

Figure 2 . FRF gauge locations

Chapter 2 Meteorology

the probe was installed 3 m above ground inside a protective cover to shade it from direct sun, yet provide proper ventilation.

Results

Daily and average air temperature values are tabulated in Table 2 and shown in Figure 3.

Year Mean,-C

—* 1995 18.5 @----© 1983-95 16.0

O ° © L =) = o = © Q © ke = <x

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Month

Figure 3. Daily air temperature values with monthly means

Atmospheric Pressure

Measurement instruments

Electronic atmospheric pressure sensor. Atmospheric pressure was measured with a YSI electronic sensor with analog output located in the laboratory building at 9 m above NGVD. Data were recorded on the FRF computer. Data from this gauge were compared with those from an NWS aneroid barometer to ensure proper operation.

Chapter 2 Meteorology

Microbarograph. A Weathertronics, Incorporated (Sacramento, CA), recording aneroid sensor (microbarograph) located in the laboratory building was also used to continuously record atmospheric pressure variation.

The microbarograph was compared daily with the NWS aneroid barometer, and adjustments were made as necessary. Maintenance of the microbarograph 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.

The microbarograph was read and inspected daily using the following procedure: The pen was zeroed (where applicable). The chart time was checked and corrected, if necessary. The daily reading was marked on the chart for reference. The starting and ending chart times were recorded, as necessary. New charts were installed, when needed.

sacs

Results

Daily and average atmospheric pressure values are presented in Figure 4, and summary statistics are presented in Table 2.

Year Mean, mb

xx 1995 1016.6 @----0 1983-95 1016.9

a E © = >) 12) no ) =

a Oo

= ©

fe Q 129) fe) =

=

<

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Month

Figure 4. Daily barometric pressure values with monthly means

Chapter 2 Meteorology

Precipitation

Precipitation is generally well distributed throughout the year. Precipitation from mid-latitude cyclones (northeasters) predominates in the winter, whereas local convection (thunderstorms) accounts for most of the summer rainfall.

Measurement instruments

Electronic rain gauge. A Belfort Instrument Company (Baltimore, MD) 30-cm weighing rain gauge, located near the instrument shelter 47 m behind the dune, measured daily precipitation. According to the manufacturer, the instrument's accuracy was 0.5 percent for precipitation amounts less than 15 cm and 1.0 percent for amounts greater than 15 cm.

The rain gauge was inspected daily; however, the analog chart recorder was inoperable the entire year.

Plastic rain gauge. An Edwards Manufacturing Company (Alberta Lea, MN) True Check 15-cm-capacity clear plastic rain gauge with a 0.025-cm resolution was used to monitor the performance of the weighing rain gauge. This gauge was located near the weighing gauge, and the gauges were com- pared on a daily basis. Very few discrepancies were identified during the year.

Results

Daily and monthly average precipitation values are shown in Figure 5. Statistics of total precipitation for each month during this year and average totals for all years combined are presented in Table 2.

Wind Speed and Direction

Winds at the FRF are dominated by tropical maritime air masses that create low to moderate, warm southern breezes; arctic and polar air masses that 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 dominant wind direc- tion changes with the season, being generally from northern directions in the fall and winter and from southern directions in the spring and summer. It is common for fall and winter storms (northeasters) to produce winds with average speeds in excess of 15 m/sec.

Chapter 2 Meteorology

10

Year Total, mm

x——* 1995 1256 @----© 1980-95 1082

E E es (2) g 1o) 2 O v ao

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Month

Figure 5. Daily precipitation values with monthly totals

Measurement instrument

Winds were measured at the seaward end of the pier at an elevation of 19.1 m (Figure 2) using a Weather Measure Corporation (Sacramento, CA) Skyvane Model W102P anemometer. Wind speed and direction data were collected on the FRF computer. 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 annually at the National Bureau of Standards in Gaithersburg, MD, and is within the manufacturer's specifications.

Chapter 2: Meteorology

Results

Annual and monthly joint probability distributions of wind speed versus direction were computed. Wind speeds were resolved into 3-m/sec intervals, whereas 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. Resultant directions and speeds were also determined by vector-averaging the data (see Table 2). Wind statistics are presented in Figures 6-8.

Chapter 2 Meteorology

11

N 337.50.0 995

315.0 0

45 292.5 a tp Pee ml)

Ww 90.0E

270.0 f=

e Qe 247.5 fi Ley 112.5

225.0 [sooo

202.5 180.097" S 1995 Speed 1.1 m/s Direction 359 deg

N 337.50.0 995

315.0 5.0 67.5

Boer ys 292.5 a I

W 990.0 = | 90.0E

EL | wey 112.5

225.0 135.0

202.5 180.0 ="? S

1980-1995 Speed 0.8 m/s Direction 351 deg

Frequency, %

Figure 6. Annual wind roses

Chapter 2 Meteorology

N N 337.50.0 995 337.50.0 995

315.0 315.0 ; : Bau wt 7 67.5 ry, 3

W 90.0E W — 90.0E

27.0.0) = 270.0 (ar 3S

@

247.5 WA. wd 112.5 247.5 / i 3 * 112.5

225.0 135-0 225.0 202.5 180.0 97° 202.5 180.0 S S JANUARY FEBRUARY Speed 1.9 m/s Speed 2.4 m/s Direction 316 deg Direction 309 deg

135.0 157.5

292.5

Wi Y W 270.0 o

247.5 Pr & Tw c 247.5 ¢4

225.0 s 225.0 202.5 180.0 202.5 180.0 S S MARCH APRIL Speed 2.9 m/s Speed 0.7 m/s Direction 5 deg Direction 77 deg

Frequency, %

Figure 7. Monthly wind roses for 1995 (Sheet 1 of 3)

Chapter 2 Meteorology

14

N 337.50.0 995 315.0 45.0

292.5 AY 7,

Wome oC =i 90.0E

Sy <> 247.5 f i LN 112.5

135.0

67.5

225.0 202.5 180.0 °° S MAY Speed 0.5 m/s Direction 136 deg

315.0

292.5

Ww — 90.0E

270.0 S

ny, re 112.5

135.0

202.5 180.0 ©”">

S JULY Speed 2.2 m/s Direction 181 deg

Frequency, %

Figure 7. (Sheet 2 of 3)

N 337.50.0 995

45.0 A 292.5 ale Whe ors & Fs

W700 oe — 90.0E

¢ S 247.5 ¢] " yb 112.5

225.0 135.0

202.5 180.0'°7"° S JUNE Speed 1.5 m/s Direction 65 deg

N 337.50.0 995

oo

315.0 )

202.5 180.0 S

AUGUST Speed 2.8 m/s Direction 30 deg

Chapter 2: Meteorology

ie) 9

90.0E

3

N N 337.5 0.0 337.50.0 995 315.0 45.0 Oe Woes) A 292.5 2 VA : S Ps comm) a aa: ¢

207.5 Og io 112.5

225.0 135.0

202.5 180.0 97-5 202.5 180.0 97:5 S S SEPTEMBER

OCTOBER Speed 4.4 m/s Speed 0.5 m/s Direction 43 deg Direction 68 deg

N N 337/510:0)) 551s B/S OO on 5 315.0

AM é 67.5

10)

45. a} 5 67.5 aN Fs W 270.0 os 90.0E Ww |

270.0 o=

055 L b ae wis” ¢ 4 a Y 225.0 :

SR 135.0 202.5 180.0 7°

202.5 180.0 '7-> S Ss NOVEMBER

DECEMBER Speed 3.1 m/s Speed 2.9 m/s Direction 293 deg Direction 322 deg

90.0E

112.5

Frequency, %

Figure 7. (Sheet 3 of 3)

Chapter 2 Meteorology

N 337.50.0 995 315.0

N 337.50.0 995

y 1 45.0 315.0 q f. 67.5 a ie 292.5 a , 292.5

en as 5 90.0E W 970.0 = 90.0E

247. eo; ee 112.5

225.0 135.0

202.5 180.0 7" S JANUARY Speed 2.2 m/s Direction 331 deg

N 337.50.0 995 315.0 45.0

247.5 "Spur me 112.5

225.0 135.0 (5725)

202.5 180.0 S FEBRUARY Speed 1.9 m/s Direction 341 deg

N 337.50.0 995 315.0 45.0

292.5 i: ; ee 292.5 ale, cis

W 970.0 iz S 90.0E Wee ee S 2 90.0E

247.5 “ti “we 112.5 247.5 ar Ty 112.5

225.0 135.0 225.0 135.0

202.5 180.0 7? 202.5 180.0 ">

S MARCH Speed 1.3 m/s Direction 351 deg

S APRIL Speed 0.2 m/s Direction 320 deg

Frequency, %

Figure 8. Monthly wind roses for 1980 through 1995 (Sheet 1 of 3)

Chapter 2 Meteorology

N

337.50.0 995 315.0 45.0

292.5 es I>,

W 970.0 cal

247. y ff we

225.0 157.5

202.5 180.0 S MAY Speed 0.3 m/s Direction 150 deg

N 337.50.0 995

67.5

90.0E

112.5

135.0

315.0 45.0

292.5 Pec i> XG Da W 570.0 —_ =>

aoe

202.5 180.0 °7> S JULY Speed 2.0 m/s Direction 206 deg

Figure 8. (Sheet 2 of 3)

Chapter 2 Meteorology

67.5

90.0E

112.5

135.0

Frequency, %

N 337.50.0 995 315.0 45.0

292.5 att is eee

ro Ww 270.0 2 90.0E

Y) iw 112.5

225.0 135.0

202.5 180.0 °7"°

S JUNE Speed 1.0 m/s Direction 184 deg

N 337.50.0 995

HEZS) 225.0 135.0 202.5 180.0 7° S AUGUST Speed 0.5 m/s Direction 84 deg

17

18

N 337.50.0 995 315.0

AY

270.0 2

247.5 ° 225.0 135.0 202.5 180.0 7° S

90.0E

cml Sy \

112.5

SEPTEMBER Speed 2.0 m/s Direction 39 deg

N 337.50.0 995 315.0 45.0

292.5 ant 2 ee,

W 90.0E

270.0 & is 247.5 “Cy . 112.5 225.0 135.0 APB comes S

NOVEMBER Speed 1.7 m/s Direction 347 deg

Frequency, %

Figure 8. (Sheet 3 of 3)

N 337.50.0 995

202.5 180.0 S

OCTOBER Speed 2.3 m/s Direction 26 deg

N 337.50.0 995 315.0

5.0 a! 5 67.5 292 SN VA

202.5 180.0'°/° S DECEMBER Speed 2.4 m/s Direction 331 deg

Chapter 2 Meteorology

3 Waves

This chapter presents summaries of the wave data. A discussion of individual major storms is given in Chapter 9 and contains additional wave data for times when wave heights exceeded 2 m at the seaward end of the FRF pier. Appendixes B through E provide more extensive data summaries for each gauge, including height and period distributions, wave direction distributions, persistence tables, and spectra during storms.

Wave directions (similar to wind directions) at the FRF are seasonally 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 that approach twice as frequently from north of the pier. Annually, waves are approximately evenly distributed between north and south (resultant wave direc- tion being almost shore-normal).

Measurement Instruments

The wave gauges included one wave staff gauge (Gauge 625), one buoy gauge (Gauge 630), and two pressure gauges (Gauges 111 and 641) as shown in Figure 2. Staff gauge 645 failed in May 1992 and was replaced by pressure gauge 641 at the same location. The gauges were located as follows:

Distance Offshore Water Depth Operational Gauge Type/Number from Baseline Period

Continuous wire (645) 238 m 5 11/84-05/92 Pressure Gauge (641) 238 m ap) 11/92-12/95 Continuous wire (625) 567 m 11/78-12/95 Accelerometer buoy (630) 6 km 11/78-12/95

Staff gauges One Baylor Company (Houston, TX) parallel cable inductance wave gauge (Gauge 625 at sta 18+60 (Figure 2)) was mounted on the FRF pier.

Rugged and reliable, this gauge requires little maintenance except to keep tension

Chapter 3 Waves

20

on the cables and to remove any material that may cause an electrical short between them. It was calibrated prior to installation by creating an electrical short between the two cables at known distances along the cable and recording the voltage output. Electronic signal conditioning amplifiers are used to ensure that the output signals from the gauge are within a 0- to 5-V range. Manufacturer- stated gauge accuracy is about 1.0 percent, with a 0.1-percent

full-scale resolution; full scale is 14 m for Gauge 625. This gauge is susceptible to lightning damage, but protective measures have been taken to minimize such occurrences. A more complete description of the gauges’ operational characteristics is given by Grogg (1986).

Buoy gauge

One Datawell Laboratory for Instrumentation (Haarlem, The Netherlands) Waverider buoy gauge (Gauge 630) measures the vertical acceleration produced by the passage of a wave. The acceleration signal is double-integrated to produce a displacement signal transmitted by radio to an onshore receiver. The manufac- turer stated that wave amplitudes are correct to within 3 percent of their actual value for wave frequencies between 0.065 and 0.500 Hz (corresponding to 15- to 2-sec wave periods). The manufacturer also specified that the error gradually increased to 10 percent for wave periods in excess of 20 sec. The results in this report were not corrected for the manufacturer's specified amplitude errors. However, the buoy was calibrated semiannually to ensure that it was within the manufacturer's specification.

Pressure gauges

One Senso-Metrics, Incorporated (Simi Valley, CA), pressure transduction gauge (Gauge 111) installed near the ocean bottom measures the pressure changes produced by the passage of waves creating an output signal that is linear and proportional to pressure when operated within its design limits. Predeployment and postdeployment calibrations are performed at the FRF using a static deadweight tester. The sensor's range is 0 to 25 psi (equivalent to 0 to 17 m of seawater) above atmospheric pressure with a manufacturer-stated accuracy of +0.25 percent. Copper scouring pads are installed at the sensor's diaphragm to reduce biological fouling, and the system is periodically cleaned by divers.

One Paroscientific, Incorporated (Redmond, WA) pressure transduction gauge (Gauge 641) was installed near the ocean bottom on an instrument pile under the pier at station 7+80. Calibration is similar to that performed on Gauge 111. The sensor's range is 0 to 45 psia (equivalent to 0 to 30 m of seawater) with a manufacturer-stated accuracy of +0.01 percent. A perforated copper/nickel plate protects the sensor's diaphragm from biological fouling, and the system is periodically cleaned by divers.

Chapter 3 Waves

Digital Data Analysis and Summarization

The data were collected, analyzed, and then archived on optical disk using the FRF's VAX computer. Data sets were normally collected every 3 hr. For each gauge, a data set consisted of five contiguous records of 4,096 points recorded at 0.5 Hz (approximately 34-min long), for a total of 2 hr and 50 minutes, resulting in only a 10-min gap between data sets. Analysis was performed on individual 34-min records.

The analysis program computes the first moment (mean) and the second moment about the mean (variance) and then edits the data by checking for "jumps," "spikes," and points exceeding the voltage limit of the gauge. A jump is defined as a data value greater than five standard deviations from the previous data value, whereas a spike is a data value more than five standard deviations from the mean. If less than five consecutive jumps or spikes are found, the program linearly interpolates between acceptable data and replaces the erroneous data values. The editing stops if the program finds more than five consecutive jumps or spikes, or more than a total of 100 bad points, or the variance of the volt- age is below 1 x 10° squared volts. The statistics and diagnostics from the analysis are saved.

Sea surface energy spectra are computed from the edited time series. Spectral estimates are computed from smaller data segments obtained by dividing the 4,096-point record into several 512-point segments. The estimates are then ensemble-averaged to produce a more accurate spectrum. These data segments are overlapped by 50 percent (known as the Welch (1967) method) which has been shown to produce better statistical properties than nonoverlapped segments. The mean and linear trends are removed from each segment prior to spectral analysis. To reduce side-lobe leakage in the spectral estimates, a data window was applied. The first and last 10 percent of data points were multiplied by a cosine bell (Bingham, Godfrey, and Tukey 1967). Spectra were computed from each segment with a discrete Fast Fourier Transform and then ensemble-averaged. Sea surface spectra from subsurface pressure gauges were obtained by applying the linear wave theory transfer function.

Unless otherwise stated, wave height in this report refers to the energy- based parameter H,,, defined as four times the zeroth moment wave height of the estimated sea surface spectrum (i.e., four times the square root of the variance) computed from the spectrum passband. Energy computations from the spectra are limited to a passband between 0.05 and 0.50 Hz for surface gauges and between 0.05 Hz and a high-frequency cutoff for subsurface gauges. This high-frequency limit is imposed to eliminate aliased energy and noise measurements from biasing the computation of H,,, and is defined as the frequency where the linear theory transfer function is less than 0.1 (spectral values are multiplied by 100 or more). Smoother and more statistically significant spectral estimates are obtained by band-averaging contiguous spectral components (three components are averaged per band,

Chapter 3 Waves

21

producing a frequency band width of 0.0117 Hz).

Wave period 7, is defined as the period associated with the maximum energy band in the spectrum, which is computed using a 3-point running average band on the spectrum. The peak period is reported as the reciprocal of the center frequency (i.e., 7, = 1/frequency) of the spectral band with the highest energy. A detailed description of the analysis techniques is presented in an unpublished report by Andrews (1987).'

Results

The wave conditions for the year are shown in Figure 9. For all four gauges, the distributions of wave height for the current year and all years com- bined are presented in Figures 10 and 11, respectively. Distributions of wave period are presented in Figure 12.

Multiple-year comparisons of data for Gauge 111 actually incorporate data for 1985 and 1986 from Gauge 640 (a discontinued Waverider buoy previously located at the approximate depth and distance offshore of Gauge 111) and data for 1987 from Gauge 141, located 30 m south of Gauge 111. In addition, Gauge 511 was used from January through October 1993. Multiple-year data for Gauge 641 also include data from Gauge 645 (a Baylor staff gauge) which was mounted at the same location as Gauge 641 from November 1984 until May 1992, when it failed.

Refraction, bottom friction, and wave breaking contribute to the observed differences in height and period. 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 and occasionally 1 km offshore. This occurrence is a major reason for the differences in the distributions between Gauge 630 and the inshore gauges.

The wave height statistics for the pressure gauge (Gauge 641), located at the landward end of the pier, were considerably lower than those for the other gauges. In all but the calmest conditions, this gauge is within the breaker zone. Consequently, these statistics represent a lower energy wave climate.

1M. E. Andrews. (1987). "Standard wave data analysis procedures for coastal engineering applications," unpublished report prepared for U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS.

Chapter 3 Waves

Jun

13 5 7 9 1113 15 17 19 2123252729 1 3 5 7 9 11 13 15 17 19 2123 25 27 29 31 Day of the Month

S57 0 NSB WD M2827 1357 9 Nii Y © 21282327 ew wt Day of the Month

Figure 9. 1995 time-histories of wave height and period for Gauge 630

Chapter 3 Waves

23

E ic oe

oO ae

OR 10° “10 Percent Greater Than Indicated

Figure 10. 1995 annual wave height distributions

GW

sf

J 4

|

=|

|

|

4

: al 4

4

|

=

5]

1

iO 10° 10 Percent Greater Than Indicated

Figure 11. Annual distribution of wave heights for 1980 through 1995

on Chapter 3 Waves

Gauge 625 1995 | Gauge 625 1980-95

20-4 7 al | y) | : VIZ Z

| _plBoatlon_|_..0aelhboo

4075

= Gauge 630 1995 Gauge 630 1980-95

|_effaoelo.1_nAageBZboo_

Gauge 111 1995 Gauge 111 1985-95

iY Acre | _.o@oodleo1_onBolAoo

40 i Gauge 641 Gauge 641 1980-95

~ o O e = = = ) O oO om 3 > S S ® >) a 2 uc

Z Y, oa - WA F aA VIO ; | CAGE Dea F 86 7 8 9 0 2 ie ie 8 910 12 14 16 Period, sec eriod, sec

Figure 12. Annual wave period distributions for all gauges

Summary wave statistics for the current year and all years combined are presented for Gauge 630 in Table 3.

Chapter 3 Waves

Table 3

Wave Statistics for Gauge 630

Month

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Annual

26

1995 1980-1995 Height Period Height Period Std. Std. Std. Std. Mean Dev. Extreme Mean Dev. Number Mean Dev. Extreme Mean Dev. m om _om Date sec _sec

UUWRONERRRAUG : ‘

.

. . ° . CE OieiteeOie One) ee oa ONONUANMNUNAUN

. oe se FUOFN-WADOMWO—= . ee e 8 .

OP OWUNOWAOUONON UNFUNODWWOON OW HNNNNNNNWNNW

ONUDmMUOMNWNO OoO0O0O00 0000000 ‘ SOOO SCS E26

Oo REABNDAONDY MMO OM MVYOO MMO WoaNWoeonaankro NNNMNMNN WNW NM PH Ph PP

!

OOO0O0O0C0COCO0C0C0C°O NNNNAF AH AH AaANNNN ROW -DCANANANO®D =] 92220000 = = a=

. O60 ar NPN -ANWDONNN

oO oa S N oo i Nm ul = (=) f=) on a 5 = fos) W N

Annual joint distributions of wave height versus wave period for Gauge 630 are presented for 1995 in Table 4, and for all years combined in Table 5. Similar distributions for the other gauges are included in Appendixes B-E.

Annual distributions of wave directions (relative to true north) based on daily observations of direction at the seaward end of the pier and height from Gauge 625 (or Gauge 111 when data for Gauge 625 were unavailable) are shown in Figure 13. Monthly wave roses for 1995 and all years combined are presented in Figures 14 and 15, respectively.

Chapter 3 Waves

Table 4

Annual (1995) Joint Distribution of H_. versus 7, for Gau

mo p

Period, sec

e 8 8 8 ororOoOrROF

WWNrmHN--ooO

Greater 3 6 Q ° . c Total 36 144 532 1148 1377 1141

1 Percent occurrence (x100) of height and period.

Table 5 Annual (1980-1995) Joint Distribution of H

Height, m

ououoUoOWUoOWOo o00o00000000 '

' WWrHNA] oOo e 8 8 8 © 8 « 28 orOoOrOrOL 0 00000 0 0

UPN mp] R-] O° o ss «8 a

- Greater 6 5 - J O O Total 57 160 458 1150 1406 1116

1 Percent occurrence (x100) of height and period.

Chapter 3 Waves

10.0- 12.0- 14.0- 16.0- 11.9 _13.9 _15.9 _Longer

10.0- 12.0- 14.0- 16.0- 13.9

Total

27

1995 Height 0.8 m Direction 66 deg

1980-1995 Height 0.8 m Direction 66 deg

Height, m

20 Frequency, %

Figure 13. Annual wave roses

28

Chapter 3 Waves

Chapter 3 Waves

S JANUARY Height 0.9 m Direction 65 deg

S MARCH Height 1.0 m Direction 65 deg

Height, m

0) 20 Frequency, %

FEBRUARY Height 0.6 m Direction 55 deg

a 6 we] 90.0E ae

112.5

S APRIL Height 0.7 m Direction 67 deg

Figure 14. Monthly wave roses for 1995 (Sheet 1 of 3)

29

30

Height 0.8 m Direction 70 deg

S JULY Height 0.5 m Direction 89 deg

(0)

Figure 14. (Sheet 2 of 3)

Height, m

20 Frequency, %

S JUNE Height 0.6 m Direction 73 deg

S AUGUST Height 1.1 m Direction 73 deg

Chapter 3 Waves

S) S SEPTEMBER OCTOBER Height 1.1 m Height 0.8 m Direction 63 deg Direction 76 deg

157.5

S S NOVEMBER DECEMBER Height 0.7 m Height 0.7 m Direction 53 deg Direction 53 deg

Height, m

0 20 40 60 80 Frequency, %

Figure 14. (Sheet 3 of 3)

Chapter 3 Waves

32

JANUARY Height 0.9 m Direction 58 deg

MARCH Height 0.9 m Direction 64 deg

Figure 15. Monthly wave roses for 1980 through 1995 (Sheet 1 of 3)

0)

112.5

135.0 157.5 S FEBRUARY Height 0.9 m Direction 58 deg

APRIL Height 0.8 m Direction 68 deg

20 Frequency, %

Chapter 3 Waves

Height 0.7 m Direction 72 deg

JULY Height 0.4 m Direction 85 deg

Figure 15. (Sheet 2 of 3)

Chapter 3 Waves

(0)

JUNE Height 0.5 m Direction 78 deg

AUGUST Height 0.6 m Direction 76 deg

Height, m

20 Frequency, %

33

34

SEPTEMBER Height 0.8 m Direction 69 deg

OCTOBER Height 0.9 m Direction 67 deg

Owl) e

112.5

135.0

S NOVEMBER Height 0.9 m Direction 61 deg

(0)

Figure 15. (Sheet 3 of 3)

DECEMBER Height 0.9 m Direction 58 deg

Height, m

20 Frequency, %

Chapter 3 Waves

4 Currents

Surface current speed and direction at the FRF are influenced by winds, waves, and, indirectly, by the bottom topography. The extent of the respective influences varies daily. However, winds tend to dominate the currents at the seaward end of the pier, whereas waves dominate within the surf zone.

Observations

Near 0700 EST, 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 a small wooden block floating on the water surface.

Results

Annual mean and mean currents for 1980 through 1995 are presented in Table 6 and in Figure 16. Figure 16 shows the daily and average annual measurements at the beach, pier midsurf, and pier end locations. Since the relative influences 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 locations. Magnitudes generally are largest at the midsurf location and lowest at the end of the pier.

Chapter 4 Currents

35

36

Table 6

Mean Longshore Surface Currents’

Pier End, cm/sec Pier Midsurf, cm/sec 1980-

1995 1995

southward; - = northward.

Beach, cm/sec

Chapter 4 Currents

” SS € Oo me) fd) o jee WY _ (S oO \ S =) (S)

Pier Midsurf

Year Mean, cm/s

—_—_* 1995 15 @-=-01980-95 13

Year Mean, cm/s

—_—* 1995 15 @---01980-95 7

Rach (GOO tm Uschi) q4-

Mean, cm/s

——~«1995 . 4 @---01980-95 3

290) —— Aa. Ga

Jan Feb Mar Apr May Jun Jul Aug Month

[=a alta tle Delpos fh Sea Tl

Sep Oct Nov Dec

Figure 16. Daily current speeds and directions with monthly means for 1995

Chapter 4 Currents

S)7/

38

5 Tides and Water Levels

Measurement Instrument

From 1978 to June 1995 water level data were obtained from an 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, OR), digital tide gauge. 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.

Operation and tending of the tide gauge conformed to NOS standards. The gauge was checked daily for proper operation of the punch mechanism and for accuracy of the time and water level information. The accuracy was determined by comparing the gauge level reading with a level read from a refer- ence electric tape gauge. 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 severe, divers in- spected and cleaned the orifice opening as required.

The tide station was inspected quarterly by an NOAA/NOS tide field group. Tide gauge elevation was checked using existing NOS control positions, and the equipment was checked and adjusted as needed. Both NOS and FRF personnel also reviewed procedures for tending the gauge and handling the data. Any specific comments on the previous months of data were discussed to ensure data accuracy.

Digital paper tape records of tide heights taken every 6 min were analyzed by the Tides Analysis Branch of NOS. An interpreter created a digital magnetic computer tape from the punch paper tape, which was then processed on a large computer. First, a listing of the instantaneous tidal height values was cre- ated for visual inspection. If errors were encountered, a computer program was used to fill in or recreate bad or missing data using correct values from the nearest

Chapter 5 Tides and Water Levels

NOS tide station and accounting for known time lags and elevation anomalies. When the validity of the data had been confirmed, monthly

tabulations of daily highs and lows, hourly heights (instantaneous height

selected on the hour), and various extreme and/or mean water level statistics were computed.

Following a year of comparison tests at the FRF the Leupold and Stevens, Inc., digital tide gauge was replaced in June 1995 by an NOS acoustic tide gauge (Next Generation Water Level Measurement System, NGWLMS) located at pier sta 19+20.

The following brief discription of the NGWLMS was condensed from a paper found on the NOAA World Wide Web site (Gill 1990).

The NGWLMS system’s primary sensor is a self-calibrating, downward- looking acoustic system that transmits a short acoustic pulse through a 1.3-cm- diameter sound tube to the water surface and to a calibration point referenced to the station’s datum. Because the major potential source for errors is vertical temperature changes between the sensor and the water surface, sound tube air temperatures are monitored and accompany the transmitted data. The sensor takes 181 1-sec samples in 3-min periods centered every 6 min. A new mean value and standard deviation are computed every 6-minutes. Each NGWLMS also includes a less accurate, strain-gauge type sensor as a backup. The systems relay data every 3-hrs to NOAA’s Geostationary Operational Environmental Satellite system. NOAA’s NGWLMS Data Processing and Analysis System retrieves data on an hourly basis, decodes and then performs automated quality control checks.

Results

Tides at the FRF are semidiurnal with both daily high and low tides approximately equal. Tide height statistics are presented in Table 7. Figure 17 plots the monthly tide statistics for all available data, and Figure 18 compares the distribution of daily high and low water levels and hourly tide heights. The monthly or annual mean sea level (MSL) reported is the average of the hourly heights, whereas the mean tide level 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. Mean range (MR) is the difference between MHW and MLW levels, and the lowest water level for the month is the extreme low (EL) water, while the highest water level is the extreme high (EH) water level.

NOTE: Due to a mistake in converting feet to centimeters the tide height statistics from 1987 through 1993 (as published in the 1987 through 1993 Annual Data Summaries) found in Table 7 and Figure 17 were in error. These were corrected beginning with the 1994 report.

Chapter 5 Tides and Water Levels

40

Table 7 Tide Height Statistics’

Mean Mean Mean Tide Sea Low Level Level Water

Measurements are in centimeters.

Prior Years

Extreme Low

Nov -95 Dec -84 Dec -84 Oct -100 May -94 Mar -92 Apr -86 Jan -76 Dec -108 Dec -93 Oct -77 Jan -73 Oct -108 Nov -110 Mar -119 Feb -95 Sep

Mar 1989 -119 Mar 1980

Chapter 5 Tides and Water Levels

yl / Al A We da,

Water Level, cm

1991

1987

1983 1989

1981 1985

Year

Figure 17. Monthly tide and water level statistics relative to NGVD

1995 1979-95

£ i) > @ = ‘= © & 5 =

10.00 25.00 50.00 75.00 90.00 99.00 99.90 99.99 Percent Greater Than

Figure 18. Distributions of hourly tide heights and high- and low-water levels

Chapter 5 Tides and Water Levels

41

42

6 Water Characteristics

Monthly averages of daily measurements of surface water temperature, visibility, and density at the seaward end of the FRF pier are given in Table 8. The summaries represent single observations made near 0700 EST and, therefore, may not reflect daily average conditions since such characteristics can change within a 24-hr period. Large temperature variations were common when there were large differences between the air and water temperatures and variations in wind direction. From past experience, persistent onshore winds move warmer surface water toward the shoreline, although offshore winds cause colder bottom water to circulate shoreward, resulting in lower temperatures.

Table 8

Mean Surface Water Characteristics

Temperature Visibility Density deq C a/cm®

1980- 1980- 1995 1995 1995 1.0247 1.0234 1.0251 1.0231 1.0234 1.0227 1.0243 1.0223 1.0233 1.0218 1.0213 1.0212 1.0226 1.0215 1.0224 1.0207 1.0214 1.0209 1.0234 1.0219 1.0246 1.0230 1.0248 1.0235

— NO NO ju NO

Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

eee aavyu ) SE Ra OB Ose UDROMOMNWYOW Corh>-honkRO>-aAU =2024fhuWUW WS) SES Oe ay ae RR a C2020n>2U0UUD © B32 aNWWWp ooo Se Fi Die oe BE Aa RN HOWWOKnD

= or .

1.0234 1.0221

ao nN oO N .

=

Annual

Chapter 6 Water Characteristics

Temperature

Daily sea surface water temperatures (Figure 19) were measured with an NOS water sampler and thermometer. Monthly mean water temperatures (Table 8) varied with the air temperatures (see Table 2).

Temperature Year degC

—« 1995 15.6 @----© 1980-95 14.8

©) D oO O o cs =) = o © Q = © lol ths © i o =

liemewan ylfictaeical T SPU Ly eS LT los LL JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Month

Figure 19. Daily water temperature values with monthly means

Visibility

Visibility in coastal nearshore waters depends on the amount of salts, sol- uble 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 that vary daily and yearly.

Visibility was measured with a 0.3-m-diam Secchi disk, and similar to water temperature, variation was related to onshore and offshore winds. Onshore winds moved warm clear surface water toward shore, whereas offshore winds

Chapter 6 Water Characteristics

43

44

brought up colder bottom water with large concentrations of suspended matter. Figure 20 shows the daily and monthly mean surface visibility values for the year. Large variations were common, and visibility less than 1 m was expected in any month. Monthly means are given inTable 8.

Year Mean, m

*—* 1995 2.0 @----© 1980-95 Zell

E 2 2 o >

=

oO

ie) =

SS [pe | a) | | foe a ee a er ies T T T 1 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Month

Figure 20. Daily water visibility values with monthly means

Density

Daily and monthly mean surface density values, plotted in Figure 21, were measured with a hydrometer. Monthly means are also given in Table 8. These values are direct readings from the hydrometer. Corrections for differences between ocean water temperature and jar water temperature, as well as use of

Chapter 6 Water Characteristics

uncalibrated hydrometers and other factors, could produce an error amounting to a couple of percent in the direct hydrometer readings.

Year Mean, g/cm?

%——*1995 1.0234 == 1980-95 1.0221

Le)

5

S fon) >

5 3) Cc ©

a

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Month

Figure 21. Daily water density values with monthly means

Chapter 6 Water Characteristics

45

7 Surveys

Waves and currents interacting with bottom sediments produce changes in the beach and nearshore bathymetry. These changes can occur very rapidly in re- sponse to storms, or slowly as a result of persistent but less forceful seasonal variations in wave and current conditions.

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 between 1.0 and 2.0 m). This pattern is interrupted in the immediate vicinity of the pier where a permanent trough runs under much of the pier, ending in a scour hole where depths can be up to 3.0 m greater than the adjacent bottom (Figure 22). This trough, which apparently is the result of the interaction of waves and currents with the pilings, varies in shape and depth with changing wave and current conditions.

Figure 22. Permanent trough under the FRF pier, 25 January 1995

Chapter 7 Surveys

The effect of the pier on shore-parallel contours occurs as far as 300 m away, and the shoreline may be affected up to 350 m from the pier (Miller, Birkemeier, and DeWall 1983).

Approximately once a month, surveys were conducted of an area extend- ing 600 m north and south of the pier and approximately 950 m offshore. These surveys were conducted to document the temporal and spatial variability in bathymetry. Contour maps resulting from these surveys, along with plots of change in elevation between surveys, are given in Appendix A.

All surveys used the Coastal Research Amphibious Buggy, a 10.7-m-tali amphibious tripod described by Birkemeier and Mason (1984), in combination with a Geodimeter 140-T self-tracking, electronic theodolite, distance meter. Profile locations are shown in each figure in Appendix A. 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.

A history of bottom elevations below Gauges 645 and 625 is presented in Figure 23 for pier stations 7+80 (238 m) and 18+60 (567 m), along with intermediate locations, 323 and 433 m.

(m) 238

SL el oo i eee Sp T Se a ead a nt fen =} JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Month

Figure 23. Time-history of bottom elevations at selected locations under the FRF pier

Chapter 7 Surveys

Distance

47

48

8S Photography

Aerial Photographs

Aerial photographs are taken annually using a 23-cm aerial mapping cam- era 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. The flight lines covered are shown in Figure 24. Figure 25 is a sample of the imagery obtained on 14 January 1991; the available aerial photographs for the year are:

Date Flight Lines Format

18 October Black/White Color

Beach Photographs

Daily color slides of the beach were taken using a 35-mm camera from the same location on the pier looking north and south (Figure 26). The location from which each picture was taken, as well as the date, time, and a brief description of the picture, were marked on each of the slides.

Chapter 8 Photography

CHE SAPEAKE BAY

“Ky ALBEMARLE SOUND

pes oe

ann ee > see ets ED Be mo a

PAMLICO SOUND

CAPE HATTERAS

Figure 24. Aerial photography flight lines

Chapter 8 Photography 49

:12,000)

1

14 January 1991 (Scale

Sample aerial photograph,

Figure 25

Chapter 8 Photography

50

North View South View

4 So

c. 14 March 1995

Figure 26. Beach photos looking north and south from the FRF pier (Sheet 1 of 4)

Chapter 8 Photography

51

South View

North View

11995

ri

Qo. <x + ee

d

£14 June 1995

igure 26. (Sheet 2 of 4)

F

Chapter 8 Photography

52

Figure 26. (Sheet 3 of 4)

Chapter 8 Photography

— 8 ae

South View

eran Racer

St

y Vy 7)

ee

53)

54

Figure 26.

(Sheet 4 of 4)

eee

j. 14 October 1995

South View

Chapter 8 Photography

9 Storms

This chapter discusses storms (defined here as times when the wave height parameter H,,, equaled or exceeded 2 m at the seaward end of the FRF pier). Sample spectra from Gauge 630 are given in Appendix B. Prestorm and/or poststorm bathymetry diagrams are given in Appendix A. Tracking information was provided by NOAA Daily Weather Maps (U.S. Department of Commerce 1995).

Chapter 9 Storms

55

56

15-16 January 1995 (Figure 27)

Following the passage of a cold front, onshore winds (from northeast) generated by a high pressure system reached 15 m/sec at 1216 EST on 15 January. The maximum H,,, (at Gauge 630) reached 3.2 m (7, = 11.10 sec) at 1634 EST also on 15 January. There was 41 mm of precipitation.

Atmospheric Pressure, mb Gauge 616

2 |

Gauge 932

990 ot Wind Speed, m/sec

Wind Direction, Deg True N

Wave Height, Hy, Mm

Gauge 630

Gouge 3111

Water Level from NGVD, m Gauge 11

6 JANUARY, 1995

Figure 27. Data for 15-16 January 1995 storm

Chapter 9 Storms

28-29 January 1995 (Figure 28)

A strong Canadian high pressure system in conjunction with an approaching storm produced onshore winds at the FRF beginning on 28 January. As the storm moved off the North Carolina coast it quickly intensified generating winds (from northeast) of 13 m/sec at 0208 EST on 29 January. Waves at Gauge 625 reached a maximum H,,, of 2.10 m (T, = 7.3 sec) at 0208 EST also on 29 January. There was 5 mm of precipitation.

Gauge 616

Gouge 932

Wave Height, H,,, m Gouge 625

Gauge 625

Wave Period, Tp, sec

Gouge 3111

-204

Water Level from NGVD, m

JANUARY, 1995

Figure 28. Data for 28-29 January 1995 storm

Chapter 9 Storms

57

2 March 1995 (Figure 29)

Northerly winds funneled between a Canadian high pressure system and a small low pressure system located offshore of Cape Hatteras, NC, briefly generated storm waves at the FRF. Waves at Gauge 625 reached a maximum H,,. of 2.3 m (T,, = 9.8 sec) at 1142 EST on 2 March. Onshore winds (from the north) peaked at 16 m/sec at 0842 EST also on 2 March. The FRF received 13 mm of precipitation from this storm.

10405 Atmospheric Pressure, mb Gauge 616

1030-4 1020+ 2 Oe eer ge ee a 10104

10004

990+-—+ Toonslimmlisantiomn’ imma 'ieealimey imme! nema” rs Wind Speed, m/sec Gauge 932

Gauge 625

Gauge 625

Gauge 3111

MARCH, 1995

Figure 29. Data for 2 March 1995 storm

58 Chapter 9 Storms

7-8 August 1995 (Figure 30)

A strong pressure gradient created by a Canadian high pressure system and a weak storm off Cape Hatteras, NC produced northeasterly winds of 10 m/sec, which peaked at 0400 EST on 8 August. The maximum H,,,, (at Gauge 625) of 2.3 m (J, = 10.2 sec) was recorded at 2116 EST on7 August. There was 25 mm of precipitation at the FRF.

10405 Atmospheric Pressure, mb Gauge 616

10304 1020-4 ee ee ea On na

10004

9904 tt Wind Speed, m/sec

Wave Height, H,,,, m Gauge 625 Gauge 625 Wave Direction, Deg True N Gauge 3111

ee

Water Level from NGVD, m Gauge 11

Trea me ems Tc oe TTT TT TT Tea] 8

9 AUGUST, 1995

Figure 30. Data for 7-8 August 1995 storm

Chapter 9 Storms

59

15-18 August 1995-Hurricane Felix (Figure 31)

Developing in the mid-Atlantic, Felix moved northwest then turned to the west on 15 August steering directly for the North Carolina coast. Downgraded from a category 3 to a 1 (on the Saffir/Simpson Scale) Felix stalled when he collided with a trough of low pressure entrenched along the East coast, then moved offshore, never making landfall. Maximum onshore winds (from northeast) at the FRF reached 17 m/sec at 1816 EST on 16 August. The maximum H,,, (at Gauge 630) of 4.6 m (7, = 15.1 sec) was measured earlier that morning at 0208 EST. There was 6 mm of precipitation.

Atmospheric Pressure, mb

Wind Speed, m/sec

Wind Direction, Deg True N

Wave Height, Hj, m

Wave Period, T,, sec

Wove Direction, Deg True N

-204 25 Water Level from NGVD, m

Figure 31. Data for Hurricane Felix, 15-18 August 1995

60

Chapter 9 Storms

18-20 August 1995 (Figure 32)

Strong winds associated with the interaction of a Canadian high pressure system with the remnants of Hurricane Felix reached 14 m/sec (from northeast) at 1742 EST on 19 August. The maximum /#/,,, (at Gauge 630) reached 3.5 m (J, = 14.2 sec) at 1708 EST on 19 August. There was no

precipitation.

Atmospheric Pressure, mb Gauge 616

Wind Speed, m/sec Gauge 932

Wind Direction, Deg True N

Wave Height, H,,5, ™ Gauge 630

Gauge 3111

Gauge 11

AUGUST, 1995

Figure 32. Data for 18-20 August 1995 storm

Chapter 9 Storms

61

28 August 1995 (Figure 33)

A combination of a Canadian high pressure system and a low off the North Carolina coast produced onshore winds (from northeast) of 15 m/sec at 1934 EST on 28 August. The maximum H,,, (at Gauge 625) reached 2.2 m (T, = 6.6 sec) at 1900 EST also on 28 August. There was 22 mm of

precipitation.

Atmospheric Pressure, mb

Gauge 3111

Water Level from NGVD, m Gouge 11

oe a Oo oh ST

-1 29 30

27 28 AUGUST, 1995

Figure 33. Data for 28 August 1995 storm

62 Chapter 9 Storms

19 September 1995 (Figure 34)

Northeasterly winds associated with a Canadian high pressure system reached 13 m/sec at 1034 EST on 19 September. The maximum H,,, (at Gauge 625) of 2.1 m (J, = 8.26 sec) followed at 1108 EST. There was no precipitation during this event.

1040- Atmospheric Pressure, mb Gauge 616 1030- 10204 1010 ell 900d sp SSS eS es De ee |

257 Wind Speed, m/sec Gauge 932

Tas me Oe Te Tee Tec oa Wind Direction, Deg True N

Wave Height, H,,5, m Gauge 625

FF ETF I Wave Period, Tp, sec Gauge 625

a a a a ea a a DT Wave Direction, Deg True N Gauge 3111

Water Level from NGVD, m

SEPTEMBER, 1995

Figure 34. Data for 19 September 1995 storm

Chapter 9 Storms

64

23 September 1995 (Figure 35)

Strong onshore winds were generated at the FRF preceding an advancing warm front. The maximum H,,, (at Gauge 625) of 2.1 m (7, = 6.9 sec) was attained at 1000 EST on 23 September. Maximum winds (from the northeast) reached 15 m/sec earlier at0916 EST. There was no precipitation.

1040-

10304

Atmospheric Pressure, mb

Gauge 616

1020 Se ees ae SE Ea

10104

10004

CO a a a a a a oe ee ee

Wind Direction, Deg True

Wave Height, H,,,, m

Gauge 933

Gauge 625

a eT TT TT

Wave Period, T,, sec

CSS SS Sea

16075

1004

-1

22

Wove Direction, Deg True N

Gauge 625

Gauge 3111

Water Level from NGVD, m

ae ee

Gauge 11

23 SEPTEMBER, 1995

i Wate) Oe, /RNGTEN GEN JON ~— Ss =

24 25

Figure 35. Data for 23 September 1995 storm

Chapter 9 Storms

29-30 September 1995 (Figure 36)

Northeasterly winds associated with a Canadian high pressure system reached 13 m/sec at 0434 EST on 30 September. The maximum H,,, (at Gauge 625) was 2.1 m (T, = 9.5 sec) at 0542 also on 30 September. There was

3 mm of precipitation.

1040-5 Atmospheric Pressure, mb Gauge 616

10505

10204

10105

100074 99 OF oot

Wind Speed, m/sec Gauge 932

Wind Direction, Deg True N

Wave Height, H,,,, m Gauge 625

Ce Dn De ne ee | Wave Period, T,, sec Gauge 625

Wave Direction, Deg True N Gauge 3111

Woter Level from NGVD, m Gauge 11

SEPTEMBER, 1995

Figure 36. Data for 29-30 September 1995 storm

Chapter 9 Storms

66

References

Bingham, C., Godfrey, M. D., and Tukey, J. W. (1967). "Modern techniques of power spectrum estimation." JEEE Trans. Audio Electroacoustics. AU-15, 56-66.

Birkemeier, W. A., and Mason, C. (1984). "The CRAB: A unique nearshore surveying vehicle," Journal of Surveying Engineering, American Society of Civil Engineers, 110 (1). :

Field Research Facility. (1995 (Jan-Dec)). "Preliminary data summary," Monthly Series, Coastal Engineering Research Center, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS.

Gill, S. “NOAA’s next generation tide gauges.” http://www-.nbi.ac.uk/psms]/ gb1/noaa.html (1990).

Grogg, W. E., Jr. (1986). "Calibration and stability characteristics of the Baylor Staff Wave Gage," Miscellaneous Paper CERC-86-7, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS.

Miller, H. C. (1980). “Instrumentation at CERC's Field Research Facility, Duck, North Carolina," CERC Miscellaneous Report 80-8, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS.

Miller, H. C., Birkemeier, W. A., and DeWall, A. E. (1983). "Effect of the CERC research pier on nearshore processes." Coastal Structures '83. American Society of Civil Engineers, Arlington, VA, 769-785.

U.S. Department of Commerce. (1995). "Daily weather maps," Weekly Series, Washington, DC.

Welch, P. D. (1967). "The use of Fast Fourier Transform for the estimation of power spectra: A method based on time averaging over short modified periodograms." IEEE Trans. Audio Electroacoustics. AE-15, 70-73.

References

Appendix A Survey Data

Contour diagrams constructed from the bathymetric survey data are presented in this appendix. The profile lmes surveyed are identified on each diagram. Contours are in half-meter increments referenced to NGVD. The distance off- shore is referenced to the FRF monumentation baseline behind the dune.

Changes in FRF bathymetry diagrams constructed by contouring the difference between two contour diagrams are also presented with contour intervals of 0.25 m. Wide contour lines show areas of erosion. Other areas correspond to areas of accretion. Although these change diagrams are based on considerable interpola- tion of the original survey data, they do facilitate comparison of the contour diagrams.

Appendix A Survey Data

Al

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Appendix A Survey Data

A2

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Suajau ul Uidap ‘GE idy 1Z ‘AsjatuAujog 444

Wi ‘aouDIsIq

A3

Appendix A Survey Data

FRF Pier 650

SS x»

Changes Since 21 Apr 95 (0.25 m Contours)

FRF Pler

oO XIX An WNatiatial

450 Distance, m

650

Distance, m

450

n = ® _— oO £ c= — Q oO me} Te) (op) c =) Ss ass > — _ ®O ~ x= _ je} faa) Li oO [Ln

lu ‘aouDISIG

Figure A3. FRF bathymetry, 14 June 1995 (depths relative to NGVD)

Appendix A Survey Data

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Appendix A Survey Data

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Appendix A Survey Data

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Appendix A Survey Data

A8&

Appendix B Wave Data for Gauge 630

Wave data summaries for Gauge 630 for 1995 and for 1980 through 1995 are presented in the following pages:

Daily H,,, and 7,,

Figure B1 displays the individual wave height H,,, and peak spectral wave period T, values, along with the monthly mean values.

Joint Distributions of H,,, and 7,

Annual and monthly joint distribution tables are presented in Tables B1 and B2, and data for 1980 through 1995 are in Tables B3 and B4. Each table gives the frequency (in parts per 10,000) for which the wave height and peak period were within the specified intervals; these values can be converted to percent- ages by dividing by 100. Marginal totals are also included. The row total gives the number of observations out of 10,000 that fell within each specified peak period interval. The column total gives the number of observations out of 10,000 that fell within each specified wave height interval.

Cumulative Distributions of Wave Height

Annual and monthly wave height distributions for 1995 are plotted in cu- mulative form in Figures B2 and B3. Data for 1980 through 1995 are plotted in Figure B4.

Appendix B Wave Data for Gauge 630

B1

Peak Spectral Wave Period Distributions

Annual and monthly peak wave period T, distribution histograms for 1995 are presented in Figures BS and B6. Data for 1980 through 1995 are presented in Figure B7.

Persistence of Wave Heights

Table B5 shows the number of times in 1995 when the specified wave height was equaled or exceeded at least once during each day for the duration (consecutive days). Data for 1980 through 1995 are averaged and given in Ta- ble B6. An example is shown below:

Height Consecutive Day(s) or Longer m 8 13 15 16 17 18 19+

24 21 18 14 8

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

This example indicates that wave heights equaled or exceeded 1.0 m 50 times for at least 1 day; 34 times for at least 2 days; 24 times for at least 3 days, etc. Therefore, on 16 occasions the height equaled or exceeded 1.0 m for 1 day exactly (50 - 34 = 16); on 10 occasions for 2 days; on 3 occasions for 3 days, etc. Note that the height exceeded 1 m 50 times for 1 day or lon- ger, while heights exceeded 0.5 m only 18 times for this same duration. This change in durations occurred because the longer durations of lower waves may be interspersed with shorter, but more frequent, intervals of higher waves. For example, one of the times that the wave heights exceeded 0.5 m for 16 days may have represented three times the height exceeded 1 m for shorter durations.

Spectra

Monthly spectra for the offshore Waverider buoy (Gauge 630) are present- ed in Figure B8. The plots show "relative" energy density as a function of wave frequency. These figures summarize the large number of spectra for each

B2 Appendix B Wave Data for Gauge 630

month. The figures emphasize the higher energy density associated with storms, as well as the general shifts in energy density to different frequencies. As used here, "relative" indicates the spectra have been smoothed by the three- dimensional surface drawing routine. Consequently, extremely high- and low- energy density values are modified to produce a smooth surface. The figures are not intended for quantitative measurements; however, they do provide the energy density as a function of frequency relative to the other spectra for the month.

Monthly and annual wave statistics for Gauge 630 for 1995 and for 1980 through 1995 are presented in Table B7.

Figure B9 plots monthly time-histories of wave height and period.

Appendix B Wave Data for Gauge 630

B3

B4

Wave Height, m

Wave Period, sec

Figure B1.

OF al esate Ge aa iG Greases eae ean a7 aa nena ato ayes, U

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Month

Year Mean, sec x— 1995 8.4

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Month

1995 daily wave height and period values with monthly means for Gauge 630

Appendix B Wave Data for Gauge 630

Table B1 Annual Joint Distribution of H,,, versus 7,

Annual 1995, Gauge 630 Percent Occurrence (X100) of Height and Period

Height (m) Period(sec)

10.0- 12.0- 14.0- 16.0- 11.9

-49 22 .99 22 49 : -99

49

off)

-49

-99

-00 -49

-50 99)

-00 - Greater

Total

-00 -50 -00 -50 -00 -50 -00 -50

UP PWWNNPRP OO PPWWNNPRP OO

Appendix B Wave Data for Gauge 630

Table B2 Monthly Joint Distribution of H,,, versus 7,

January 1995, Gauge 630 Percent Occurrence (X100) of Height and Period

Height (m) Period(sec)

10.0- 12.0- 14.0- 16.0- 11.9 13.9

-49 5 - : 163 -99 : 976 3 = 81 -49 . > 163 569 9 5 - 6

-99 . ° ° 2

49 : cS 5 81

-99

49

-99

-00 -50 -00 -50 -00 -50 -00 -50 .00 ~49 -50 -99 -00 - Greater 0 : 2 0 Total 569 1707

UP RWWNNPPOO PPWWNNHP OO

February 1995, Gauge 630 Percent Occurrence (X100) of Height and Period

Height (m) Period (sec)

10.0- 12.0- 14.0- 16.0- 11.9 13.9 _15.9 _Longer

49 268 99 -49 Eto,9) -49 -99 -49 .99 -00 -49 -50 -99 -00 - Greater Total

-00 -50 -00 -50 -00 -50 -00 -50

PPWWNNRP POO

0 0 1 1 2 2 3 3 4 4 5

March 1995, Gauge 630 Percent Occurrence (X100) of Height and Period

Height (m) Period (sec)

10.0- 12.0- 14.0- 16.0- slab) aly ©)

UPPWWNNPP OO PPWWNNH HOO

167 1417

(Continued) (Sheet 1 of 4)

Appendix B Wave Data for Gauge 630

Table B2 (Continued)

April 1995, Gauge 630 Percent Occurrence (X100) of Height and Period

Height (m) Period (sec)

10.0- 12.0- 14.0- 16.0- abbas) alt}a©)

83 167 o 83 583 s00 167

UP PWWNNPRP OO PPWWNNRPP OO

May 1995, Gauge 630 Percent Occurrence (X100) of Height and Period

Height (m) Period (sec)

10.0- 12.0- 14.0- 16.0- 11.9 13.9

s65 1048 242 887 81

QO. 0 0. c¢) abe 1 1. 1 2, 2 Zo 2 Zo 3 3. 3 4. 4 4. 4 S.

404 888 2580 323 1130

June 1995, Gauge 630 Percent Occurrence (X100) of Height and Period

Height (m) Period (sec)

10.0- 12.0- 14.0- 16.0- 11-9 13.9

167 5 : 167 1333 6 167 83 333 5 O

UPPWWNNRPRPOO PPWWNNP POO

250 1999 1500

(Continued) (Sheet 2 of 4)

Appendix B Wave Data for Gauge 630

Table B2 (Continued)

July 1995, Gauge 630 Percent Occurrence (X100) of Height and Period

Height (m) Period(sec)

10.0- 12.0- 14.0- 16.0- 11.9 _13.9 _15.9 _Longer

+49 : : : . ¢ 244 407 0 399) 732 813 569 407 1057 1545 2927 81 -49 2 5 d 81 Q } ° ° - 2,9) 6

49

-99

49

-99

-00 -50 -00 -50 -00 -50 -00 -50 -00 -49 -50 -99 .00 - Greater . . . . . 5 . . . Total 894 569 651 1057 1789 3334

UP PWWNNPRP OO PPWWNNHPH OO

August 1995, Gauge 630 Percent Occurrence(X100) of Height and Period

Height (m) Period (sec)

10.0- 12.0- 14.0- 16.0- 11.9 13.9 _15.9 _Longer

PPWWNNRPPRP OO

0. 0. Sh abo oy. 2h 3. 3. 4. 4. 5.

September 1995, Gauge 630 Percent Occurrence (X100) of Height and Period

Height (m) Period (sec)

10.0- 12.0- 14.0- 16.0- TI9 S39)

164 1311 . 656 1639 1967 492

UP PWWNHNPRPOO PPWWNNPHOO

820 3442 1967

(Continued) (Sheet 3 of 4)

Appendix B Wave Data for Gauge 630

Table B2 (Concluded)

October 1995, Gauge 630 Percent Occurrence (X100) of Height and Period

Height (m) Period (sec)

10.0- 12.0- 14.0- 16.0- stab ke) altye®)

351 439 351 351 1754 1053 351 263 702 877 526 263 439 263 5 88 : 0

UP RPWWNNPHP OO PPWWNNEPP OO

614 1404 1228 965 2017 1492 351

November 1995, Gauge 630 Percent Occurrence (X100) of Height and Period

Height (m) Period (sec)

10.0- 12.0- 14.0- 16.0- stat) _skeia®)

-00 0.49

-50 0.99

-00 1.49

-50 1.99

-00 2.49

-50 2.99

-00 3.49

-50 3.99

-00 4.49 3 3 0 6 8 c 0 D - -

-50 4.99 ¢ ° : 5 : 7 : O - 9 =

-00 - Greater : ° : : - r a Total 169 1440

i0} te) 1 1 2 2 3 3 4 4 5

December 1995, Gauge 630 Percent Occurrence (X100) of Height and Period

Height (m) Period (sec) 10.0- 12.0- 14.0- 16.0- alah ok) —akzyn©)

-00

-50

-00

-50

-00

-50

-00 49

-50 -99

-00 4.49

-50 4.99

.00 - Greater c 0 0 Total 81 564 1049

-49 -99 -49 -99 -49 of)

UP PWWNNPPRP OO WWNNrFROO

Seen

(Sheet 4 of 4)

Appendix B Wave Data for Gauge 630

B9

Table B3 Annual Joint Distribution of H,,, versus 7, (All Years)

Annual 1980-1995, Gauge 630 Percent Occurrence (X100) of Height and Period

Height (m) Period (sec)

10.0- 12.0- 14.0- 16.0- flab of) _alt}©)

PPWWNNP POO

QO. O. aba ake Zi. 2. 3 3% 4. 4. Sie

Bue Appendix B Wave Data for Gauge 630

Table B4 Monthly Joint Distribution of H,,, versus 7, (All Years)

January 1980-1995, Gauge 630 Percent Occurrence (X100) of Height and Period

Height (m) Period(sec)

10.0- 12.0- 14.0- 16.0- alak of)

12 12 6

6

UBbADWWNNHPHOO PWWNNPHOO

February 1980-1995, Gauge 630 Percent Occurrence (X100) of Height and Period

Height (m) Period (sec)

10.0- 12.0- 14.0- 16.0- 11.9 : 15.9 _Longer

7 7

PWWNNHFPPOO

oO. QO. a5 abo 2h ie Sle 3. 4. 4. Sr

March 1980-1995, Gauge 630 Percent Occurrence (X100) of Height and Period

Height (m) Period (sec)

10.0- 12.0- 14.0- 16.0- 11.9 13.9 15.9 _Longer

UP PRPWWNNRPHOO PWWNNPRPOO

(Continued) (Sheet 1 of 4)

Appendix B Wave Data for Gauge 630 B11

B12

Table B4 (Continued)

Height (m)

UP PWWNHNRPHPOO

-00 -50 -00 510) -00 -50 -00 -50 -00 -50 -00

PPWWNNEPr OO

Total

-49 ~99 -49 99) -49 99) -49 -99 -49 -99 Greater

Height (m)

QO. O. abe obo 2. 2. 3. 3. 4. 4. Sys

PPWWNNRPP OO

Height (m)

UP PWWNNPRPPRP OO

PRWWNNRPP OO

April 1980-1995, Gauge 630 Percent Occurrence(X100) of Height and Period

Period(sec) 10.0- 12.0- 14.0- 16.0- 15.9 Longer

11

May 1980-1995, Gauge 630 Percent Occurrence (X100) of Height and Period

Period (sec)

10.0- 12.0- 14.0- 16.0- alah a&) ale3a©

June 1980-1995, Gauge 630 Percent Occurrence (X100) of Height and Period

Period(sec)

Ee ee

10.0- 12.0- 14.0- 16.0- aisha Sy atz} ae)

1359 1555

(Continued) (Sheet 2 of 4)

Appendix B Wave Data for Gauge 630

Table B4 (Continued)

Height (m)

UPR WWNNPHOO PPWWNNPRPOO

520

Height (m)

266 141

0. 0 QO. 0 1. 1 abo 1 2. 2 2. 2 3. 3 So 3 4. 4 4. 4 5.

Height (m)

-00 -50 -00 -50 -00 -50 -00 -50 -00 -49

-50 -99

-00 - Greater

Total

-49 -99 0 117 233 -49 0 12 87 -99 6 ° 12 -49 -99 -49 o£)f)

UP PWWNNRPHOO PPWWNNEP OO

Appendix B Wave Data for Gauge 630

July 1980-1995, Gauge 630 Percent Occurrence (X100) of Height and Period

Period(sec)

10.0- 12.0- 14.0- 16.0- alzye&)

148 46

August 1980-1995, Gauge 630 Occurrence (X100) of Height and Period

Period (sec)

10.0- 12.0- 14.0- 16.0- alabok) ott} 5©)

28

September 1980-1995, Gauge 630 Percent Occurrence(X100) of Height and Period

Period(sec)

10.0- 12.0- 14.0- 16.0- 13.9

6

6 6 6

(Continued) (Sheet 3 of 4)

B13

B14

Table B4 (Concluded)

Height (m)

-00 -50 -00 -50 -00 -50 -00 -50 -00 -50

UP PWWNNRPHP OO PPWWNNHPP OO

Total

49 -99 49 -99 -49 -99 -49 -99 49 399 -00 - Greater

Height (m)

QO. QO. aba 1. 26 2. 3. Ze 4. 4. Sr

PWWNNRPOO

Height (m)

-00 -50 -00 -50 -00 -50 -00 -50 -00 -50

UP PWWNNPP OO

Total

-00 Greater

31 169

October 1980-1995, Gauge 630 Percent Occurrence (X100) of Height and Period

Period (sec)

10.0- 12.0- 14.0- 16.0- 11.9 : 15.9 _Longer

November 1980-1995, Gauge 630 Percent Occurrence(X100) of Height and Period

Period(sec)

10.0- 12.0- 14.0- 16.0- bat) SlE}GE) SAE) suey eee

19 38 19

6

December 1980-1995, Gauge 630 Percent Occurrence (X100) of Height and Period

Period(sec)

EEE eS ee ee

-O- 10.0- 12.0- 14.0- 16.0- alah at)

6

269 25

194 3 19 13

eee ee ee

(Sheet 4 of 4)

Appendix B Wave Data for Gauge 630

S ore ie 2

o aie

TO 0 nanny] Tai ine Ti | Om 10° 10 Percent Greater Than Indicated

Figure B2. Annual cumulative wave height distributions for Gauge 630

Appendix B Wave Data for Gauge 630 B15

Tan Ener

fone Erne Se

a qd |

es peed | es

Ww

ifn nenenneneen

i)

1

[e) i) tb

10 10° 10 Percent Greater Than Indicated

[e)

Figure B3. 1995 monthly wave height distributions for Gauge 630

Bie Appendix B Wave Data for Gauge 630

- 1)

W hone nen een n

4

i

W

p po een nnn 1

No

Om 10° 10 Percent Greater Than Indicated

Figure B4. 1980-1995 monthly wave height distributions for Gauge 630

Appendix B Wave Data for Gauge 630

B17

40- Gauge 625 i995) iI (Gatige! 625 1980-95

205 aR

|__ofGieee: ao_1__eogadaee_

40-5 = Gauge 630 1995} Gauge 630 1980-95

20-4

|_ oa@Agee2.0_}_ no B2e828 oo

40

Gauge 111 1995 Gauge 111 198595)

__at@eodan_| .nbel Gen

40 | Gauge 641 Gauge 641 1980-95

20

Xx oO S) (S © = = =) ) Oo

o)

—_ ° > S = © =) on ®

uo

(0)

Aeasgeay?se 92 1B Period, sec

Figure B5. Annual wave period distributions for all gauges

Bie Appendix B Wave Data for Gauge 630

405

Jan

204 mr y ees

40-7 Feb

tie oJ _anlldedonn.

4075 Mar

|__.20484i io

4075

20

A 207

EZ eames |. be becan..

4075

X oO ) < ® = Ss =) ) O

oO

_— ) > Ss) Ss ® 5 > 2

fie

May

204 | Z uA Wino whp:

] Jul j | G ade eae

Aug

| y : fe ae | Sep y Al ee a

5

Oct

| ae Ar | -aleenden

| ; |__ ofan _2

Nea CAL 910 12 14 16 riod, sec

Figure B6. 1995 monthly wave period distributions for Gauge 630

Appendix B Wave Data for Gauge 630

B19

Jan 7 Ju

1 AV Zi ! Le _oAfao8o._]_ odo

Feb Aug

| ml Z Ap | pfootlo |. anBelBd

=

ar | . 7 Sep b: __ntoeede | ..08e8eben_

Apr 4 Oct

| aAaeleb noi _pAGeledon_

~ oO (6) (= oO ws tS =) Oo [S) ie) = e) > (S) (S oO =) oF 2 es

May 1 Nov

| Else ae |__ 3400870

Figure B7. 1980-1995 monthly wave period distributions for Gauge 630

B2 9 Appendix B Wave Data for Gauge 630

Table B5 1995 persistence of H,,, for Gauge 630

1 2 3 4 5 6 7 8 atal ale als} alts lS 6 4

08) -0 15) -0 -5 -0 as) -0

Table B6 1980 through 1995 persistence of H,,,, for Gauge 630

Height Consecutive Day(s) or Longer (m) 1 2 3 4 5 6 7 8 9 1) as te gD ab ah 2G

19 aks} lal 10 9 8 7 6 5 10 3 2

PwWWnNDdNeP PO

Appendix B Wave Data for Gauge 630 B21

B22

RELATIVE ENERGY DENSITY

RELATIVE ENERGY DENSITY

ZING

ze Sh

yy

= |

ar

\

——

V7 Dns

S2 So2 ae.

22> SeSsIN Sosse2 sos

Lye? Lf

anerr

NU,

o>

L? Ope

is va ee ea Lol oh i | "\

gy

N

LITT I

Figure B8. 1995 monthly spectra for Gauge 630 (Sheet 1 of 6)

Appendix B Wave Data for Gauge 630

re WS

a >. ff we Seay LYN

we

wg oa

RELATIVE ENERGY DENSITY

RELATIVE ENERGY DENSITY

ASS

Ses cose Ssessee SSE cook SSF LS <<2 a, Res = ape 22 a SS

Figure B8. (Sheet 2 of 6)

Appendix B Wave Data for Gauge 630 B23

RELATIVE ENERGY DENSITY

RELATIVE ENERGY DENSITY

“<< Ssce 22 Roc oS SSSes co <7 a SS SSeS ose [7 sees Lf ALL So ree SALLI TTT] 22 Soe ——

Figure B8. (Sheet 3 of 6)

Bat Appendix B Wave Data for Gauge 630

SA

RELATIVE ENERGY DENSITY

RELATIVE ENERGY DENSITY

N

ay

Soe Sse2

Poses 2SsceSee CeSScoesss <L2es5 Soe, 255252255 Lose5 cesses 22

rr SoS LOSS 22

Figure B8. (Sheet 4 of 6)

Appendix B Wave Data for Gauge 630 B25

RELATIVE ENERGY DENSITY

RELATIVE ENERGY DENSITY

Figure B8. (Sheet 5 of 6)

Bz6 Appendix B Wave Data for Gauge 630

AVE GA 199s CE 830

rae STR ea Sq Be ml Le oF S277 i , HH

Spell

ip

is

RELATIVE ENERGY DENSITY

327) tes

RELATIVE ENERGY DENSITY

V/ C27 L|

SSS

Figure B8. (Sheet 6 of 6)

Appendix B Wave Data for Gauge 630 B27

Table B7 Wave statistics for Gauge 630

1995 1980-1995 Height Period Height Period Std. 0 Std. Std. Mean Dev. Extreme G Mean Dev. Extreme Mean Dev. Number Obs.

1619 1464 1811 1790 1837 1717 1752 1768 1715 1843 1588 1599

WHANIWRPONDH PH

PR DNOMHOMRIMPM® IMP I]

owNI oONIUMNPNHN YH HY

CROWN IWLMWNON SOOO OOOO O COO Oo UNwW PON PPh HU NNNN PPP PNND Ww UIP UOHWAwWYDW PNNNNNNNHWNDN W w©IUuWONOMNWIO PeRERPHOOOOrRPKREH PR NPNPOMWYBAWOCNNN ceooeceoeoea OOOO OBYIIYANAUH HY PU HIYA A UNUN DPF NNWU PU A DRPPPNPIMR CYR WY oO OO MD} OO MM Ow NNNNNNNNNNNDN

ZT. abo abo 0 0 0 te) 1 1 ake 1 abe

6.1 Sep 1985 8.3 2.6 20503

B28 Appendix B Wave Data for Gauge 630

Appendix B Wave Data for Gauge 630

4

NM Re INN

(jl NN SEEN ey ie ne Pe ih 2-4

pie Ad NS SSSI dE SS yal Mar Sep

PE SOS ta 7a Geneseo CR Opel oe Ee oe as

pe ea Sr ad Apr Oct

Q < ie) <

13937 9 WIS WW Alesse e7 a9 1 8 SY O18 18 WD Al 82S 7 OD) oh Day of the Month

4 Jan Jul 4 Feb Aug

SSB7 9 NW RY © 2282779 18 8 7 © NW W 212925 27 2 Bi Day of the Month

Figure B9. Time-histories of wave height and period for Gauge 630

B29

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REPORT DOCUMENTATION PAGE ee |

. TITLE AND SUBTITLE 5. FUNDING NUMBERS Annual Data Summary for 1995 CHL Field Research Facility; Volume I: Main Text and Appendixes A and B; Volume II: Appendixes C Through E

. AUTHOR(S)

| | | | Michael W. Leffler, Clifford F. Baron, Brian L. Scarborough, Paul R. Hodges, | C. Ray Townsend

|7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION U.S. Army Engineer Waterways Experiment Station REPORT NUMBER 3909 Halls Ferry Road, Vicksburg, MS 39180-6199 Technical Report CHL-98-14

19. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING/MONITORING

U.S. Army Corps of En gineers AGENCY REPORT NUMBER

Washington, DC 20314-1000

11. SUPPLEMENTARY NOTES Available from National Technical Information Service, 5285 Port Royal Road, Springfield, VA 22161.

}12a. DISTRIBUTIONWAVAILABILITY STATEMENT 12b. DISTRIBUTION CODE

Approved for public release; distribution is unlimited.

13. ABSTRACT (Maximum 200 words)

This report provides basic data and summaries for measurements made during 1995 at the U.S. Army Engineer Waterways Experiment Station (WES), Coastal and Hydraulics Laboratory’s (CHL’s) Field Research Facility (FRF) in Duck, NC. The report includes comparisons of the present year’s data with cumulative statistics from 1980 to the present.

Summarizes in this report are meteorological and oceanographic data, monthly bathymetric survey results, sam- ples of biannual aerial photography, and descriptions of 10 storms that occurred during the year. The year was high- lighted by Hurricane Felix, which impacted the North Carolina coast on 15-18 August.

This report is the 17th in a series of annual summaries of data at the FRF that began with Miscellaneous report CERC-82-16, which summarizes data collected during 1977-1979. These reports are available from the WES Tech- nical Report Distribution Section of the Information Technology Laboratory, Vicksburg, MS.

. SUBJECT TERMS 15. NUMBER OF PAGES | Meteorologic research—statistics (LC) an. | Oceanographic research—statistics (LC) nESIPRICE CODE Oceanographic research stations—North Carolina—Duck (LC) Cae Water waves—statistics

| |

- SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION |20. LIMITATION OF ABSTRACT | OF REPORT OF THIS PAGE OF ABSTRACT

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