JolUn: On>^- 48° -47° -46° -45° -44° -43° -42° 41° ~~\ — \ — \ \ — \ — \ — \ — \ — \ — \ — \ — \ — \ — \ — \ — \ — r" 57° 56° 55° 54° 53° 52° 51 ° 50° 49° 48° 47° 46° 45° 44° 43° 42° 41 ° 40° 39° Figure 1 International Ice Patrol's Operation Area showing bathymetry of the Grand Banks of Newfoundland 40= Patrol operating area. As in 1992, AES flew few iceberg reconnaissance flights during 1993 because of a lack of funding. AES did acquire and relay to IIP some iceberg informa- tion obtained during sea ice reconnaissance flights and there were a few flights dedicated solely to iceberg reconnaissance. During 1 993, the IIP Operations Center received a total of 8058 target sightings within its operations area and away from the New- foundland coast which were entered into HP's drift model. This can be compared to 3170 target sightings during 1992. The 8058 tar- gets entered into HP's drift model do not repre- sent all ofthe targets reported to IIP. Sightings of targets outside HP's operations area were not entered into the model. Most of these were farto the north of HP's area and were in areas not covered by HP's model. Table 2 compares the icebergs de- tected south of 48°N plus the number of ice- bergs which were predicted to drift across 48°N for each month of 1 993 with the monthly mean total from 1 983 - 1 992, the period during which IIP has been patrolling with SLAR- equipped aircraft. During the 1 993 ice year, an estimated 1 753 icebergs drifted south of 48°N; whereas, during 1992 876 icebergs drifted south of 48°N. Based on the historic iceberg counts of its entire 79 year history, IIP classi- fies the severity of the ice seasons. Ice years with fewer than 300 icebergs crossing 48°N are defined as light ice years; those with 300 to 600 crossing 48°N as average; those with 600 to 900 crossing 48°N as heavy; and those with more than 900 crossing 48°N as extreme (Alfultis, 1987). 1993 was an extreme year when compared to the entire history in addi- tion, it is well above average for the recent years in which SLAR has been used. Appen- dix D presents a detailed description of HP's reconnaissance techniques since 1960. Table 2 Number of Icebergs South of 48°N Number of icebergs South of 48'N during 1993 compared to the average for the period 1983-92, the SLAR reconnaissance f Deriod. Avg 1983-92 Ice Year 1993 1 OCT 1 0 NOV 1 0 :::::.. :DEC:.:™». ■:-:-:-:-:-;-;-:-:-:-:-:-:-:->:-:|;-;-:- _™,:.J.6..... JAN 1 112 1 FEB 36 336 MAR MAY .^,....J6^.. .276 JUN 206 188 JUL 112 50 AUG .a B"36 a SEP 6 1 ^ Era Average 927 1753 ^ The 1 993 season was the first year that IIP used its iceberg Data Management and Prediction System (DMPS). This system, which is nearly identical to the iceBerg Analysis and Prediction System (BAPS) used at the Cana- dian Ice Centre, Ottawa, combines an iceberg drift model with a deterioration model. The model uses wind, ocean current data, and iceberg size data to predict the movement and deterioration of all icebergs entered into DMPS. Appendix F presents an examination of the impact of the DMPS on MP's correlation of most recent sighting data with the predicted movement of previously sighted icebergs. The drift prediction model uses a historical current data base which is modified weekly using satellite-tracked ocean drifting buoy data, thus taking into account local, short-term, current fluctuations. Murphy and Anderson (1985) described and evaluated the drift model. The iceberg deterioration model uses daily sea surface temperature and wave height information from the U.S. Navy Fleet Numeri- cal Oceanography Center (FNOC) to predict the melt of icebergs. Anderson (1983) and Hanson (1 987) described the IIP deterioration model in detail. Eight satellite-tracked ocean drifting buoys were deployed to provide current data for MP's iceberg drift model during the 1993 season. All were World Ocean Circulation Experiment (WOCE) drifters. All buoys were equipped with temperature sensors. One of the buoys had a drogue at 15 meters and the remainder were drogued at 50 meters. Drift data from the buoys are discussed in the IIP 1993 Drifting Buoy Atlas, which is available upon request. Appendix E discusses in detail recent improvements in the drifting buoy pro- gram. llPconductedanoceanographiccruise aboard USCGC BITTERSWEET (WLB 389) between 8 and 23 July 1 993. The objective of the cruise was to provide surface tmth for an evaluation of the iceberg detection and iden- tification ability of the APS-137 Forward Looking Airborne Radar (FLAR). During the 1993 season, IIP success- fully deployed 37 Air-deployable expendable BathyThermographs (AXBTs). The AXBT measures temperature with depth and trans- mits the data back to the aircraft. Temperature data from the AXBTs were sent to the Cana- dian Meteorological and Oceanographic Cen- ter (METOC) in Halifax, Nova Scotia, Canada, the U.S. Naval Eastern Oceanography Center (NEOC) in Norfolk, Virginia, and FNOC foruse as inputs into ocean temperature models. IIP directly benefits from AXBT deployments by having improved ocean temperature data pro- vided to its iceberg deterioration model. IIP also provided weekly drifting buoy sea surface temperature (SST) and drift histories to METOC and NEOC for use in water mass and SST analyses. Canada's Maritime Command/ Me- teorological and Oceanographic Centre pro- vided the AXBT probes for I IP use, significantly increasing the temperature data IIP could obtain. On April 15. 1993, IIP paused to re- member the 81st anniversary of the sinking of the RMS TITANIC. During an ice reconnais- sance patrol, two memorial wreaths were placed near the site of the sinking to com- memorate the neariy 1500 lives lost. 8 Iceberg Reconnaissance and Communications During the 1993 Ice Patrol year, 154 aircraft sorties were flown in support of IIP. Of these, 55 were transit flights to St. John's, Newfoundland, MP's base of operations since 1989, and 75 were ice observation flights made to locate the southwestern, southern, and southeastern limits of icebergs. Seven- teen logistics flights were required to support and maintain the patrol aircraft. Tables 3 and 4 show aircraft use during the 1993 ice year. HP's aerial ice reconnaissance was conducted with SLAR and FLAR-equipped U.S. Coast Guard HC-130H and a SLAR- equipped HU-25B aircraft. The HC-130H aircraft used on Ice Patrol are based at Coast Guard Air Station Elizabeth City, North Caro- lina, and HU-25B aircraft at Coast Guard Air Station Cape Cod, Massachusetts. This was the first operational year for the FLAR, an Inverse Synthetic Aperture Ra- dar (ISAR). IIP conducted a field test of the iceberg detection and identification ability of the FLAR in 1991 and as noted before, con- ducted an other test during 1993. The earlier test showed the FLAR to be a promising iden- tification tool although the FLAR failed to de- tect some small icebergs and growlers (Ezman, Murphy, Fogt, Reed, 1991). The analysis of 1993's data has not been completed. How- ever, the operational expehence gained in 1 993 show the SLAR/FLAR combination to be a vast improvement in iceberg identification over the SLAR only system. The combined ability of the SLAR and FLAR to detect icebergs in all weather and MP's computer modelsto estimate iceberg drift and deterioration enables llPto schedule aerial iceberg surveys every other week rather than every week. The HC-130H 'Hercules' aircraft has been the primary platform for Ice Patrol aerial reconnaissance since 1963, while the HU- 25B has been used since 1 988. The extended iceberg distribution throughout most of the Table 3 Aircraft Used During The 1993 IIP Year "\ Sorties Aircraft HC-130H HU-25B Total Transit 49 6 55 Patrol 59 16 75 Research 3 0 3 Logi$tics 17 4 21 Tptal 128 26 154 Fliaht Hours Aircraft HC-130H HU-25B Total Transit 149.0 11.5 160.5 Patrol 393.1 42.2 435.3 Research 16 0 16 Logistics 45.3 9.9 55.2 Tptal 603.4 63.6 667.0 _J \ Table 4 Iceberg Reconnaissance Sorties HU-25B J HC-130 rOTAL MONTH SORTIES FMQHT HOMR5 $oRTie$ FUQHT H9UR5 SORTIES FLIGHT HOyRS JAN 0 0 7 44.8 7 44.8 FEB 0 0 6 39.9 6 39.9 MAR 0 0 9 61.2 9 61.2 APR 0 0 11 76.8 11 76.8 MAY 0 0 13 85.2 13 85.2 JUN 9 25.5 8 53.1 17 78.6 JUL 7 16.7 5 32.1 12 48.8 AUG 0 0 0 0 0 0 SEP 0 0 0 0 0 0 ^ TOTAL 16 42.2 59 393.1 75 435.3 x: Table 5 Iceberg and SST Reports Number of ships furnishing Sea Surface Temperature (SST) reports 52 Number of SST reports received 278 Number of ships furnishing ice reports 340 Number of ice reports received 837 First Ice Bulletin 021200Z FEB 93 Last Ice Bulletin 301200ZJUL93 Number of facsimile charts transmitted 1 79 ^ ^ 10 1 993 season required the use of the HC-1 30 rather than the HU-25B. Thus, the HU-25B logged significantly fewer IIP flight hours than the HC-1 30. The total number of flight hours increased slightly from 623.6 hours in 1 992 to 667.0 hours in 1993. The number of sorties decreased from 1 67 in 1 992 to 1 54 in 1 993. Each day during the ice season, IIP prepared and distributed ice bulletins at OOOOZ and 1200Z to warn mariners of the south- western, southern, and southeastern limits of icebergs. U. S. Coast Guard Communications Station Boston, Massachusetts, NMF/NIK, and Canadian Coast Guard Radio Station St. John's NewfoundlandA/ON were the primary radio stations responsible for the dissemination of the ice bulletins. Other transmitting stations for the bulletins included METOC Halifax, Nova Scotia/CFH, Canadian Coast Guard Radio Station HalifaxA/CS, Radio Station Bracknel, UK/GFE, and U.S. Navy LCMP Broadcast Stations Nortolk/NAM, Virginia, and Key West, Florida. On 25 Mar 1 993, IIP began broadcasting the OOOOZ and 1200Z ice bulle- tins (in addition to safety broadcasts) over the INMARSAT-C SafetyNet AOR-W satellite. request is shown in Table 5. Appendix C lists all contributors. IIP received relayed informa- tion from the following sources during the 1 993 ice year: Canadian Coast Guard Marine Radio Station St. John's VON ; Canadian Coast Guard Vessel Traffic Centre/Ice Operations St. John's; Ice Centre Ottawa; Canadian Coast Guard Marine Radio HalifaxA/CS; ECAREG Halifax, Canada; U.S. Coast Guard Communi- cations and Master Station Atlantic, Chesa- peake, Virginia; and U.S. Coast Guard Auto- mated Merchant Vessel Emergency Re- sponse/Operations Systems Center, Martinsburg, WV. Commander, International Ice Patrol extends a sincere thank you to all stations and ships which contributed reports. The vessel with the most reports was the MA/ SYN PULKU, a Polish flag vessel. Canadian Forces 727th Communica- tions Squadron/St. John's Military Radio served as the primary facility for air ground communi- cations, and the 726th Communications Squadron/Halifax Military Radio was the sec- ondary facility. IIP also prepared adaily facsimile chart, graphically depicting the limits of all known ice, for broadcast at 1600Z daily. U. S. Coast Guard Communications Station Boston as- sisted with the transmission of these charts. Canadian Coast Guard Radio Station St. John'sA/ON and U.S. Coast Guard Communi- cations Station Boston/NIK provided special broadcasts as required. As in previous years. International Ice Patrol requested that all ships transiting the area of the Grand Banks report ice sightings, weather, and sea surface temperatures via Canadian Coast Guard Radio Station St. John'sA/ON or U. S. Coast Guard Communi- cations Station Boston/NIK. Response to this 11 12 Discussion of Ice and Environmental Conditions Background The 1993 Season The Labrador Current is the main mechanism transporting icebergs south to the Grand Banks. Its relatively cold water keeps the deterioration of icebergs in transit to a minimum. The wind direction and intensity along the Labrador and Newfoundland coasts has a significant effect on iceberg drift. Icebergs can be accelerated along or driven out of the main flow of the Labrador Current (Figure 2). Departure from the Labrador Current normally slows their southerly drift and, in many cases, speeds up their rate of deterioration. Sea ice protects the icebergs from wave action, the major agent of iceberg deteriora- tion. If sea ice extends to the south and over the Grand Banks of Newfoundland, the ice- bergs will be protected longer as they drift south. When the sea ice retreats in the spring, large numbers of icebergs will be left behind on the Grand Banks. If this time of sea ice retreat is delayed by below normal air tem- peratures,the icebergs will be protected longer, and a longer than normal ice season can be expected. Less southerly sea ice extent or above normal airtemperatures may result in a shorter season. Sea ice can impede the transport of icebergs. The degree depends on the con- centration of the sea ice and the size of the iceberg. The greater the sea ice concentra- tion, the greaterthe affect on iceberg drift. The larger the iceberg, the less sea ice affects its drift. Figures 3 to 14 compare the sea ice edge during the 1 993 ice year to the mean sea ice edge. The mean sea ice edges were taken from Cote, 1989 and represent a 25 year average (1962-1987). The ice edge (sea ice concentration > = 1 /1 0) is taken from the daily Ice Analysis from Ice Centre Ottawa. Figures 15 to 29 show the Ice Patrol Limits of All Known Ice (LAKI) and the daily sea ice edge on the 1 5th and 30th day of each month during the ice season. The ice edge is taken from the Ice Centre Ottawa FICN2 daily product. The edge plotted is a coarse numeric representation of daily Ice Analysis. These figures show the distribution of all icebergs and radar contacts tracked by HP's model at the given times. Numerals are given forclarity for those one-degree squares where six or more targets are located. The following is a discussion of the environmental conditions (the meteorological and sea ice information is taken from the Ice Centre Ottawa Thirty Day Ice Forcast for North- ern Canadian Waters): December The mean airtemperatures were about 2-4°C below normal along the Labrador Coast and in East Newfoundland waters. This was due to a persisting northwesterly flow. The sea ice growth in the East Newfoundland waters was about four weeks ahead of normal (Figure 5). There were 16 icebergs crossing 48°N in December. January and February Sea ice growth along the Labrador Coast and in East Newfoundland waters was three months ahead of normal (By January, the southern limit of the sea ice was farther 13 57° 56° 55° 54° 53° 52° 51° 50° 49° 48° 47° 46° 45° 44° 43° 42° 41° 40° 39° H I I I I M I I I 1 I I M I M I I i I I I I M I M I I I I I I I I I I I I I I I I I I I I I I M I I I I I I I I I I I I I I I I I I I I M I I I denotes the Labrador Current 52' 51° E50° 49° E48° 47° 46° 45° 44° 43° 42° 41° E40° E39° 38 1 1 1 1 1 1 1 1 1 M 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 M M 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 38° 57° 56° 55° 54° 53° 52° 51° 50° 49° 48° 47° 46° 45° 44° 43° 42° 41° 40° 39° Figure 2 The Labrador Current, the main mechanism for transporting icebergs South to the Grand Banks. 14 south than at any time during an average year). The winds persisted from the north- west. During the month of January 92 ice- bergs drifted south of 48°N. The 1993 ice season opened on 2 February 1 993, on which date the southern extent of the LAKI was at 43° 50'N (Figure 15). The southern extent of the LAKI at the end of February was 41 ° 30'N. March and April In late February through early March several stormscrossedthe East Newfoundland waters, causing sea ice destruction. As a result, the sea ice edge retreated to near normal conditions (Figure 8). However, during the rest of March and April the persistent northwesterly winds maintained below normal air temperatures and a greater than normal sea ice extent (Figure 9). The southern and eastern LAKI extended as far south as 41° 30'N and as far east as 37° OO'W respectively (Figures 18-21). There were 276 and 428 icebergs south of 48°N in March and April, respectively. May and June During the latter half of May, the pre- vailing winds were from the southeast. The air temperatures during May and June were slightly above normal. This combined with the seasonal rise in air temperature caused the sea ice to retreat rapidly (Figures 1 0 and 1 1 ). The southern LAKI remained about 41° 30'N throughout most of May and June. There were 338 and 188 icebergs crossing south of 48°N in May and June, respectively. July The sea ice retreated well north of 55°N (Figures 1 2 and 1 3). There were 50 icebergs crossing south of 48°N in July. The southern extent of the LAKI was north of 45°N (Figures 26 and 27). The 1 993 ice season closed on 30 July 1993. 15 55° 50° 45° 16 17 55° 50° 45° Sea Ice Conditions FEBRUARY 19, 1993 1/10 or greater sea ice concentration (Redrawn from Ice Center Ottawa, 1 993 ) 1962-87 mean sea ice edge (Redrawn from Ice Center Ottawa. 1 989) Figure 7 55° 50° 45° Sea Ice Conditions MARCH 12, 1993 1/10 or greater sea ice concentration (Redrawn from ice Center Ottawa, 1993) 1962 -87 mean sea ice edge (Redrawn from Ice Center Ottawa. 1989) Figure 8 18 55° 50° 4S° Sea Ice Conditions APRIL 16, 1993 1/10 or greater sea ice concentration (Redrawn from ice Center Ottawa. 1 993 ) 1 962 - 87 mean sea ice edge (Redrawn from Open Water Ice Center Ottawa, 1989) *^ 19 20 21 Figure 15 International Ice Patrol Ice Plot for 0000 GMT 02 Feb 93 Showing Observed and Modeled Iceberg Positions and Sea Ice Edge 57° 56° 55° 54° 53° 52° 51 ° 50° 49° 48° 47° 46° 45° 44° 43° 42° 41 ° 40° 39° I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I U I I I I I I I I I I I I I I I I I I I I I I I M I I I I I t I I I I I I L = 44° z 43° z 42° E41° 40^ - 40' 39°r = 39^ 38 n 1 1 1 1 1 i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 i 1 1 1 1 1 i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 i 1 1 1 1 1 i 1 1 1 1 1 1 1 1 1 1 1 i 1 1 1 1 1 i 1 1 1 1 1 1 1 1 1 1 1 i 1 1 1 1 1 1 1 1 1 1 1 i 1 1 1 1 1 1 1 M 1 1 r 38° 57° 56° 55° 54° 53° 52° 51 ° 50° 49° 48° 47° 46° 45° 44° 43° 42° 41 ° 40° 39° ^ Iceberg (tor squares with tewer tlian 6 total icet)ergs) X Radar Target (for squares witti fewer than 6 total targets) N Number of Icebergs/Radar Targets Per One Degree Rectangle (for squares with 6 or more total targets) Limit of All Known Ice Sea Ice Edge 200 Meter Bathymetric Curve 22 Figure 16 International Ice Patrol Ice Plot for 0000 GMT 17 Feb 93 Showing Observed and Modeled Iceberg Positions and Sea Ice Edge 57° 56° 55° 54° 53° 52° 51 ° 50° 49° 48° 47° 46° 45° 44° 43° 42° 41 ° 40° 39° 52°q 1 1 1 1 1 M 1 1 1 1 1 1 M 1 M =1 51 °E \ — /« ; 50°E i^^f^ 49°E c 48°= Newfoundland 47°= 46°E \ ^H t \ I \i I 16 : 40N 27 ; 15 i\.. 17 \ 45°= "■-■•i 22 \ 6 i 23 ; 12 ,\ \ Jii' X 10 33^ X 24x^rA K^ 11 l.-ZB I 22 i 7 = 51° E50° = 49° E48° z 47° = 46° E45° 44°= 43°r 42°E 41°= 40°= 39°E X"-. •■* <■•• i I Jk... - = 44° = 43° = 42° t = 41° i = 40° E 39° 38°~i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 M 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 r OO 57° 56° 55° 54° 53° 52° 51 ° 50° 49° 48° 47° 46° 45° 44° 43° 42° 41 ° 40° 39° A Iceberg Limit of All Known Ice (for squares with fewer than 6 total icebergs) X Radar Target (for squares with fewer than 6 total targets) N Nunnber of Icebergs/Radar Targets Per One Degree Rectangle (for squares with 6 or more total targets) Sea Ice Edge 200 Meter Bathymetric Curve 23 Figure 17 International Ice Patrol Ice Plot for 0000 GMT 02 Mar 93 Showing Observed and Modeled Iceberg Positions and Sea Ice Edge 57° 56° 55° 54° 53° 52° 51 ° 50° 49° 48° 47° 46° 45° 44° 43° 42° 41 ° 40° 39° CQ" I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I M I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I U I I I I I I I I I I I I I I I I I I I I I I I L (-00 z51° = 50° z 49° E 48° = 47° = 46° E 45° = 44° E 43° = 42° E41° = 40° E 39° 38 n 1 1 1 1 1 i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 r 38° 57° 56° 55° 54° 53° 52° 51 ° 50° 49° 48° 47° 46° 45° 44° 43° 42° 41 ° 40° 39° ^ Iceberg (for squares with fewer ttian 6 total Icebergs) X Radar Target (for squares witti fewer tfian 6 total targets) N Number of Icebergs/Radar Targets Per One Degree Rectangle (for squares witfi 6 or more total targets) Limit of All Known Ice Sea Ice Edge 200 Meter Bathymetric Curve 24 Figure 18 International Ice Patrol Ice Plot for 0000 GMT 17 Mar 93 Showing Observed and Modeled Iceberg Positions and Sea Ice Edge 57° 56° 55° 54° 53° 52° 51 ° 50° 49° 48° 47° 46° 45° 44° 43° 42° 41 ° 40° 39° coo-JJJ-LLLLi 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 ! 1 1 1 1 1 M II 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 ! 1 1 1 1 1 ! 1 1 1 1 1 ! 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 ! 1 1 1 1 1 1 1 u 1 1 1 1 1 1 1 1 1 1 1 1 1 1 L cpo 40°: ..- 40° 39°r r 39° 38°~i 1 1 1 1 1 i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 M I i 1 1 1 1 1 M 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 M 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 r 38 57° 56° 55° 54° 53° 52° 51 ° 50° 49° 48° 47° 46° 45° 44° 43° 42° 41 ° 40° 39° Limit of All Known Ice ^ Iceberg (for squares with fewer than 6 total icebergs) X Radar Target (for squares with fewer than 6 total targets) N Number of Icebergs/Radar Targets Per One Degree Rectangle (for squares with 6 or more total targets) Sea Ice Edge 200 Meter Bathy metric Curve 25 Figure 19 International Ice Patrol Ice Plot for 0000 GMT 31 Mar 93 Showing Observed and Modeled Iceberg Positions and Sea Ice Edge 57° 56° 55° 54° 53° 52° 51 ° 50° 49° 48° 47° 46° 45° 44° 43° 42° 41 ° 40° 39^ I I I I I I I I 1 1 I I I I I I I I I I 1 1 I I I I I I I I I I I I I I I M I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I U I I I I I M I I I I I I I I I L • z 40° z 39° n 1 1 1 1 1 i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 i 1 1 1 1 1 i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 i 1 1 1 1 1 i 1 1 1 1 1 i 1 1 1 1 1 i 1 1 1 1 1 i 1 1 1 1 1 1 1 1 1 1 1 i I M 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 r 38 Iceberg (for squares with fewer tfian 6 total Icebergs) 57° 56° 55° 54° 53° 52° 51 ° 50° 49° 48° 47° 46° 45° 44° 43° 42° 41 ° 40° 39° Limit of All Known Ice w ^ , -^ Sea Ice Edqe X Radar Target ^'^y^ (for squares with fewer than 6 total targets) 200 Meter BathymetnC CurVe N Number of Icebergs/Radar Targets Per One Degree Rectangle (for squares with 6 or more total targets) 26 Figure 20 International Ice Patrol Ice Plot for 0000 GMT 15 Apr 93 Showing Observed and Modeled Iceberg Positions and Sea Ice Edge 57° 56° 55° 54° 53° 52° 51 ° 50° 49° 48° 47° 46° 45° 44° 43° 42° 41 ° 40° 39 COO-LilLLLLi I 1 1 1 1 1 1 M 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1^1 1 1 1 1 M 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 ! 1 1 1 1 1 1 1 1 1 1 I ] 1 1 1 1 1 1 1 1 1 1 m 1 1 1 1 1 1 1 1 I I I L cpo "^ 15 1 14 1^ : i\ I I ; 8:71,: \ : 10 ! 8 :1^ 50°= f/^ 111 ^ ^ \ i-'^' z51° E50° 12 8 ^ ^[^•-: 6 i Av21 19 13 ; 7 ..i:....^::|,.:.:;.:.:^|.....^^|....N.......^ i -L "■•; ii 16'-i'-14 ^ ^ ^ A; 2i ^ le'l' 25 A^ ^:/. l^ i I : \ ' ;.-V1 ! 37 : 7 ▲ i 1^; 6 : 14 23 7 : t2 39°r -40^ r 39° 38°n 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 i M 1 1 1 1 1 1 1 1 1 1 r 38 57° 56° 55° 54° 53° 52° 51 ° 50° 49° 48° 47° 46° 45° 44° 43° 42° 41 ° 40° 39° ■A Iceberg (for squares with fewer than 6 total icebergs) X Radar Target (for squares with fewer than 6 total targets) N Number of Icebergs/Radar Targets Per One Degree Rectangle (for squares with 6 or more total targets) Limit of All Known Ice Sea Ice Edge 200 Meter Bathymetric Curve 27 Figure 21 International Ice Patrol Ice Plot for 0000 GMT 30 Apr 93 Showing Observed and Modeled Iceberg Positions and Sea Ice Edge 57° 56° 55° 54° 53° 52° 51 ° 50° 49° 48° 47° 46° 45° 44° 43° 42° 41° 40° 39° cpo-LLLLLLLl I 1 1 M 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I I 1 1 1 1 1 I 1 1 1 1 I I I HJ 1 1 1 1 1 1 1 1 i 1 1 1 i i 1 1 i i i L cOo a), 51 °z < J<>..A i ^ t)l _^ /-„.:: ^ Alii 18 i 13 ; ^ , 10 i i 7 .50° 52^ E51° ^ = 40^ 38 ~l 1 1 1 1 1 i 1 1 1 1 1 1 1 1 1 1 1 i 1 1 1 1 1 i 1 1 1 1 1 i 1 1 1 1 1 1 1 1 1 1 li 1 1 1 1 1 i M 1 1 1 i 1 1 1 1 1 1 1 1 1 1 1 j 1 1 1 1 1 1 1 1 1 1 1 1 1 1 { 1 1 ! 1 1 1 1 1 1 1 1 1 1 1 i 1 1 1 1 1 1 1 1 1 1 1 r 38° 57° 56° 55° 54° 53° 52° 51 ° 50° 49° 48° 47° 46° 45° 44° 43° 42° 41 ° 40° 39° A Iceberg (for squares with fewer than 6 total Icetiergs) X Radar Target (for squares with fewer than 6 total targets) N Number of Icebergs/Radar Targets Per One Degree Rectangle (for squares with 6 or more total targets) Limit of All Known Ice Sea Ice Edge 200 Meter Bathymetric Curve 28 Figure 22 International Ice Patrol Ice Plot for 0000 GMT 15 May 93 Showing Observed and Modeled Iceberg Positions and Sea Ice Edge 57° 56° 55° 54° 53° 52° 51 ° 50° 49° 48° 47° 46° 45° 44° 43° 42° 41 ° 40° 39° COo-LUULLL I I 1 1 I 1 1 I 1 1 1 I n I 1 1 1 1 1 1 1 1 1 1 ;^l 1 1 1 1 I I I I I ) I 1 1 1 1 1 1 1 I I 1 1 1 1 1 1 1 ! 1 1 1 1 I ) 1 1 1 1 1 I 1 1 1 1 I I 1 1 I 1 1 1 1 1 I I I I M I I I Ul 1 1 I L j-po 39°r r 39° 38°n 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 r 38 57° 56° 55° 54° 53° 52° 51 ° 50° 49° 48° 47° 46° 45° 44° 43° 42° 41 ° 40° 39° ^ '^^'^^'■9 ,,, ^ «,,, K. . Limit Of All Known Ice (for squares with fewer than 6 total icebergs) X Radar Target Sea Ice Edge (for squares with fewer than 6 total targets) 200 Meter Bathy metriC CurVe N Number of Icebergs/Radar Targets Per One Degree Rectangle (for squares with 6 or more total targets) 29 Figure 23 International Ice Patrol Ice Plot for 0000 GMT 31 May 93 Showing Observed and Modeled Iceberg Positions and Sea Ice Edge 57° 56° 55° 54° 53° 52° 51 ° 50° 49° 48° 47° 46° 45° 44° 43° 42° 41 ° 40° 39° cp" I I 1 1 1 1 I I 1 1 I I I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I 1 1 IJ I 1 1 1 1 1 1 1 1 1 1 1 ! 1 1 1 1 1 ! 1 1 1 1 1 1 1 1 1 1 1 1 I 1 1 1 I I I ^1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I 1 1 1 1 1 I 1 1 1 1 1 I 1 1 I I L coo = 51° 40°z 40^ 39°z 39° Iceberg (for squares with fewer tfian 6 total icebergs) 38 ~l I I I I I I I I I I I I i M I M i I I I I I i I I I I I I I I I I I I I I I I li I I I I I i I I I M I I I I I I i I I I I I i I I I M i I I I I I i I I I I I I I I I I I i I I I I li I I I I I r 38^ 57° 56° 55° 54° 53° 52° 51 ° 50° 49° 48° 47° 46° 45° 44° 43° 42° 41 ° 40° 39° Limit of All Known Ice vd^-t* Sea Ice Edge X Radar Target r^r^/^ »« x ^ xi. • ^ (for squares with fewer than 6 total targets) 200 Meter Bathy metriC CUrVe N Number of Icebergs/Ra 8 8 8 8 ^^^^^^ 1 Januarv20. 1914 1915 — 1920 — ■ IIP established 1917-1918 No patrols due 10 WW1 : SouthemTTWsl berg lo dale 1925 — ; 30°20'N »2°3ew 1930 — — 1936 — 1 1940_ 1 ■■ 1942-1945 No patrols due to VWV2 1945 — ^^^H ■ reconnaissance 1950 — 1955 — R 1 1960 — 1965_! 1970 — 1 1975 — 1980 — 1 1 1985 — 1990 — ^ lOOC ~"^^^ 51 Figure 2 international Ice Patrol's Operation Area showing bathymetry of the Grand Banks of Newfoundland 57° 56° 55° 54° 53° 52° 51 ° 50° 49° 48° 47° 46° 45° 44° 43° 42° 41 ° 40° 39*^ 40°- I I I I I 1000 M -52° - 51° - 50° -49° - 48° -47° -46° -45° -44° -43° -42° -41° 40= 57° 56° 55° 54° 53° 52° 51 ° 50° 49° 48° 47° 46° 45° 44° 43° 42° 41 ° 40° 39° 52 more flights are required to cover the whole of the limits leaving less time to cover interior areas. When the area encompassed by the limits of iceberg danger is large, the potential for Ice Patrol reconnaissance to sight icebergs is reduced. The further north in the Labrador Current reconnaissance is conducted, the higher the density of icebergs. When all re- connaissance flights are dedicated to flying along the li mits to define the area, the potential coverage of the interior is greatly reduced and thepotential for icebergs to drift south of 48 North in the Labrador Current and never be sighted increases. The lack of interior cover- age does not effect Ice Patrol's ability to fulfill its mission but it does affect Ice Patrol's annual report of the estimate of icebergs that drift south of 48 North. Ice Patrol Reconnaissance (1960-1982) Ice Patrol conducted visual aerial re- connaissance during this period. On an as needed basis, surface patrol craft, supple- mented aerial reconnaissance. The surface patrol craft's duty was to stand by the southern most iceberg and report its position to shipping and Ice Patrol headquarters. When it melted, the patrol craft would locate and remain with the next most southern iceberg. Surface pa- trol craft were used only during the 1972 and 1 973 seasons. Vessels capable of conducting oceanographic work were deployed to the Ice Patrol operation area to conduct oceanographic research for many of the years covered by this report. These vessels were not considered surface patrol craft but did report the positions of observed icebergs. Neither the surface patrol vessels nor the research vessels con- tributed substantially to the number of iceberg sightings. Dunng the period from 1963 to 1982, Ice Patrol made iceberg survey flights north along the Labrador coast up into Baffin Bay. The iceberg sighting data from some of these flights are included in the digital database. The information entered into the data base does not representthe complete set of sightings received by Ice Patrol from these flights. Only the data contained in the retained Ice Patrol paper records was entered into the data base. These flights were used to get an early indica- tion of the upcoming season's severity and therefore did not effect the estimate of ice- bergs crossing 48 North. Coast Guard aircraft were deployed and available at a Canadian base of opera- tions throughout the season. In 1 962, the HC- 130 (B model) was introduced as the aircraft for Ice Patrol's mission replacing the R5D (average patrol length 1200 miles). The HC- 1 30 was a longer range aircraft allowing more area to be covered in a single flight. The B model ice reconnaissance flights averaged about 1500 miles in length, including transits to and from the search area. In 1 981 , the HC- 130 H model was introduced into service with Ice Patrol. This model had about 20 percent more range (average flight track length of 1800 miles) than the B model. With each increase in range, the aircraft covered more area increasing the possibility of detecting more icebergs during a single flight. From 1960 to 1970, Ice Patrol recon- naissance aircraft were based out of Argentia, Newfoundland. A permanent Coast Guard aviation detachment was stationed in Argentia with several aircraft at their disposal. This allowed for more than one aircraft to fly ice patrol reconnaissance flights to different ar- eas on the same day when the weather was good. In 1970 with the closing of the U.S. Naval AirStationatArgentia, Ice Patrol moved its base of operations to the Canadian Forces Base at Summerside, Prince Edward Island. The one aircraft used by Ice Patrol was de- ployed from Coast Guard Air Station Elizabeth City, NC and not permanently stationed in Canada. The move from Argentia to Summerside greatly increased the time re- quired to make the transit from the operating base to the iceberg search area. The increase intransit corresponded to adecrease in search time (and area) for icebergs. During periods when good weather was forecast, the aircraft would remain overnight in St. Johns, New- foundland reducing the transit time to the search area. In 1974, the Ice Patrol base of opera- tions for aerial reconnaissance was moved from Summerside to St. Johns. The base of operations remained in St. Johns through the end of the 1982 season. This change in 53 operating locations reduced the transit time to reach the selected search areas. Occasional poor terminal weather conditions (fog) at St. Johns reduced the number of potential avail- able reconnaissance days. A high percent of the poorterminal conditions days also directly reflected poor weather in the search areas. During the visual reconnaissance pe- riod, weather, both at the search area and the terminal, was a primary factor in iceberg re- connaissance flight planning. Fog is prevalent on the Grand Banks during the period of about mid-April through early July. The aircraft gen- erally flew their patrols at an altitude of about 1000 feet with a track spacing of 25 nautical miles. If the terminal weather conditions were acceptable for takeoff and return, a flight was planned for an area of the boundary of all known ice wheretheweatherwasgood. Good weather on scene was defined as having vis- ibility forecast for over at least 50 percent of the planned search area. From 1 960 to 1 982, an average of about one flight was conducted every 4.5 days during the season. Non-flying days were due to bad weather and aircraft mechanical problems. Occasional flights to the interior of the limits were also conducted. Occasionally fights to the same area on con- secutive days would be flown to evaluate radar targets detected on the previous day's flight. During the years 1960 to 1968, the percent of the area flown that was able to be effectively searched visually (where cloud cover was less than five tenths) was published in the annual Ice Patrol Bulletins. On an average, only 70 percent of the area flown was able to be searched visually. This means icebergs possibly existed undetected within the search area. During the early and mid-1970s. Ice Patrol mostly used preset flight plans to cover specific sections of the operations area. Infor- mation about these preset flight plans can be determined by reviewing the flight plans pub- lished in the Ice Patrol Bulletins forthat period. If needed, a nonstandard flight would be flown. In 1960, the only electronic method of navigation available to the Ice Patrol aircraft was LORAN-A. In 1964, Doppler navigation equipment was installed on the aircraft. The LORAN-A coverage of the Ice Patrol opera- tions area was limited and Doppler improved the navigation accuracy. In 1973, an Inertial Navigation System (INS) was installed on the Ice Patrol aircraft. INS is presently the primary navigation system on the aircraft used by Ice Patrol. This system did not require the receipt of an external signal and greatly improved the navigational capabilities of the aircraft. The cumulative error for the INS over an Ice Patrol patrol is on the orderof 1 0 nautical miles. Each improvement in the navigation capability of the patrol aircraft meant the aircraft could fly the planned patrol area more accurately with less gaps in the area coverage caused by naviga- tional errors. The improvements also meant the iceberg position reports were more accu- rate. Ice Patrol Reconnaissance (1983-Present) 1 983 saw the introduction of the APS- 135 Side Looking Airborne Radar (SLAR) aboard the assigned HC-130 H model aircraft as the primary iceberg detection tool, supple- menting the human eye. This instrument had a profound effect on Ice Patrol's reconnais- sance operations. The SLAR provided a near all weather target detection capability. It also changed our reconnaissance strategy, includ- ing aircraft deployment scheduling. Beginning as early as 1957, the Inter- national Ice Patrol had began evaluating a variety of SLARs. Although a variety of testing and evaluation was conducted, no SLAR was used on a continuous, operational basis prior to 1983. Ice Patrol used the results of the limited SLAR research flights as input into the drift prediction model, however these targets were not differentiated from visual sightings. These research flights did not contribute sig- nificantly to the number of sightings. In 1 983, SLAR became an integral part of Ice Patrol's routine reconnaissance opera- tions. The SLAR equipped aircraft conduct patrols at 6000-8000 feet. The flights are flown with a 25 nautical mile track spacing. The SLAR range used is 27 nautical miles (50 kilometers). This SLAR range combined with the track spacing allows for about 200 percent 54 coverage of the interior portion of a standard parallel leg type search (Figure 3). Moderate orgreaterturbulence and moderate orgreater precipitation reduces the SLAR's ability to detect targets. Flights are planned to avoid both of these factors. Flight cancellations due to poor on-scene weather conditions were greatly reduced with the introduction of SLAR. Also in 1983, Ice Patrol moved its base of operations from St. Johns to Gander, New- foundland. In 1988, Ice Patrol returned its base of operations to St. Johns. Both of these moves had little effect on Ice Patrol opera- tions. Although St. Johns is a little closerto the southern portion of the area of iceberg danger, the small increase in flight transit time and corresponding decrease in search area had a minimal effect on Ice Patrol reconnaissance efforts. The use of SLAR drastically altered the Ice Patrol aircraft deployment schedule. In- stead of having an aircraft deployed to Canada on a continuous basis during the ice season, a SLAR equipped aircraft was deployed for a one week period every other week. With SLAR, Ice Patrol was able to conduct a similar number of flights and increase the coverage of the operations area. Transit legs to and from the search area could be searched with SLAR, increasing area coverage per flight. During the visual flight era, the transit legs were flown at altitude, generally above the clouds and very few iceberg sightings were recorded. The change in aircraft deployment schedule placed a larger reliance on Ice Patrol's iceberg drift and deterioration prediction models. Re- search efforts during the period 1986-1988 focused on evaluating the model performance. The results indicted, with good environmental input, the models performed within acceptable errortolerances (Murphy and Anderson, 1 985, and Hanson, 1987). Research was conducted in 1984 and 1985 to evaluate the APS-135 SLAR perfor- mance. The results indicated the SLAR was a very capable iceberg detection tool (Rositter, et al., 1985 and Robe et al., 1985). In 1 989, the HU-25B Falcon jet equipped with an APS-1 31 SLAR was first used as a Ice Patrol aerial reconnaissance platform. The APS-1 31 SLAR also provides a near all- weather target detection capability. There is only one central antenna pod on the Falcon with the antenna being half as long as the antenna on the HC-130. The HU-25B is a much smaller airframe and is more suscep- tible to being rocked by air turbulence. On a turtDulence free flight, the detection capability of the APS-1 31 SLAR is similar to that of the APS-135 SLAR (Alfultis and Osmer, 1988). The Falcon's range of 700 nautical miles is considerably less than the HC-1 30 and thus it is not capable of reaching and then searching the limits of iceberg danger during the peak of the season. The HU-25B is generally only used near the beginning and end of the sea- son and is deployed in place of an HC-1 30 as part of the same every other week schedule. The HU-25B flies two three hour sorties per day compared to one seven hour sortie for an HC-1 30. The total area covered perday by the HU-25 is considerably less than the HC-130. Due to its limited range, the HU-25B has not been used extensively. Along with SLAR's operational benefits came an important problem, targetdiscrimina- tion. When unable to see the surface, the operator must decide whether the target de- tected is an iceberg or not. Farmer (1972) provides a general overview of why SLAR is a good iceberg detection tool and a description of the visual cues used to classify SLAR tar- gets. On the basis of this study, Ice Patrol decided to make identifications without seeing icebergs using the available cues. The cues on the film aid the experienced operator in determining the identification of some targets. When two looks at the same target from differ- ent legs of the search pattern are available, movement or lack of movement of the target is a particularly useful tool in deciding if a target was an iceberg or not. For targets without any cues, the operator's ability to discriminate be- tween an iceberg and a vessel correctly is only just above chance (Thayer, 1985). During the first several years use of the SLAR, the operators were learning how to use the available cues to discriminate between vessel and iceberg targets. This target dis- crimination problem effects Ice Patrol's esti- mate of the number of icebergs drifting south of 48 North. During the first several years of 55 Figure 3 A Typical Ice Patrol Parallel Leg Ice Reconnaisance Flight with 200 Percent SLAR Coverage I I ■■'T~ 1 i i I ; 1 ^ -Flight Path -SLAR Coverage \- 56 SLAR use, it is probable that some of the targets identified as icebergs from the SLAR were not icebergs but fishing boats. Although the estimate of the number of icebergs drifting south of 48 North may have been effected, the 1983-1985 seasons would still remain classi- fied as extreme. As Ice Patrol's experience with the SLAR increased, the probability of the operatorwrongly identifying atarget has been reduced but not eliminated. In light of the targetdiscrimination prob- lem, visual confirmation is still sought for ice- bergs that set the limits of the area of iceberg danger. Flights are planned during the de- ployment period to make the best use of avail- able visibility. Other Sighting Sources The estimate of the icebergs south of 48 North is made from all data collected and analyzed by Ice Patrol throughout the year. Ice Patrol actively solicits other reporting sources to supplement Ice Patrol's own data gathering efforts. Ice Patrol relies on reports from commercial shipping to help improve the quality and accuracy of the products delivered to the maritime community. As an example, in 1991 reports from shipping accounted for over 50 percent of the icebergs entered into the drift prediction model. Throughout the period covered by this paper, other sources of iceberg sighting re- ports have been added. With the addition of each new source, the potential for increasing the annual estimate of the icebergs drifting south of 48 North increases, particularly when the new source's efforts are concentrated in areas not othen/vise fully covered. The sighting source for icebergs was recorded as one of three types from 1960 to 1 981 . The three source categories used were USCG aircraft, USCG ship report, and other. IJSCG vessels transiting to and from ocean stations in the North Atlantic and vessels per- forming oceanographic research on the Grand Banks for Ice Patrol provided the sighting reports recorded under this category. Ex- amples of reports received within the "other" category includes commercial shipping re- ports, reports from commercial, U.S., and Canadian military aviation, and reports from lighthouses. Between 1981 and 1983, the sources of sighting reports entered into the drift model were not recorded and are now no longer available. In 1984, a ten category sighting source code was added to the drift model as part of the data entry procedure. In the early 1 980s, the Canadian Atmo- spheric Environment Service (AES) began flying dedicated iceberg reconnaissance flights. Funding for this program has varied and the number of reports received is directly propor- tional to funding. The AES iceberg reconnais- sance efforts to date peaked during the 1987 and 1988 seasons. AES used an APS-94E SI_AR as the primary iceberg sensor on their Electra patrol aircraft through 1 990. The APS- 94E was evaluated in 1984 and its detection capability was less than the APS-1 35 (Rossiter, et al., 1985). In 1988, a DASH-7 with a CAL SLAR was introduced into service by AES. The AES iceberg flight efforts within the Ice Patrol model area are concentrated near the sea ice edge within the Canadian exclusive economic zone. The sea ice edge is within the area of higher Iceberg density. AES iceberg dedicated flights emphasize visual searches. AES reports SLAR targets which are not visu- ally confirmed icebergs as radar targets. In about 1984, Ice Patrol began to re- ceive iceberg reports through the NOAA/U.S. Navy Joint Ice Center. The information comes from a variety of Department of Defense sources and is passed to Ice Patrol for entry into the drift prediction model. The sighting reports are spread throughout the model area. In 1986, this source accounted for an all-time high of 1 1 percent of the icebergs entered into the model. In the 1 980s, exploratory efforts to de- velopthe hydrocarbon resources on the Grand Banks began. The Hibernia oil field area lies between about 46 to 49 North on the eastern portion of the Grand Banks. The Canadian government regulations concerning drilling requires the operators to conduct surveillance for icebergs in their exploration area. Begin- ning in about 1 985, the sightings made by the hydrocariDon industry were voluntarily sup- plied to Ice Patrol. This period of activity only lasted about 4 years and led to an increase in 57 the number of sighting reports in the area of the Hibernia oil field and effected the value of the estimate of icebergs crossing 48 North for those years. In 1 989, the sighting source code used for the hydrocarbon industry was renamed "Other aerial reconnaissance." This category now includes iceberg sightings received from the Canadian Department of Fisheries and Oceans (DFO). DFO contracts flights to con- duct reconnaissance of foreign fishing vessels activity on the Grand Banks. The contractor supplies reports of the icebergs and unidenti- fied radar targets seen on each flight to Ice Patrol. The fishing activity is concentrated along the shelf break of the Grand Banks and Flemish Cap, areas of potential high iceberg density. The number of flights conducted by the contractor increased in about 1 991 with a commensurate increase in the number of ice- berg reports. The sighting code used by the model was changed in 1989 to accommodate a new source of icebergs. The AES iceBerg Analysis And Prediction System (BAPS) models ice- berg drift in an area to the north of Ice Patrol's model area. AES supplied the predicted posi- tions of those icebergs which were predicted to have drifted across 52 North and Ice Patrol entered them into its model. This particular source did not affect the estimate of icebergs drifting south of 48 north because none of these icebergs reached 48 North prior to either melting or being resighted by another source closer to 48 North. Modeling Of Iceberg Drift The Ice Patrol models described below were operated only during the portion of the year of iceberg danger. Generally, this would be about one month on both sides of the period when Ice Patrol daily bulletins were issued. This means that reports of icebergs received outside of this period may not have been included in the annual estimate of the number of icebergs crossing 48 North. 1960 to 1971 From 1960 to 1971, Ice Patrol main- tained a hand plot of the iceberg's predicted motion. Ice Patrol used vector addition of the effects of the wind and sea current on icebergs to predict their motion. The exact origin and basis of this technique was not recorded but was based upon research conducted by Ice Patrol since its inception. The wind component vector was com- puted as the downwind direction plus 50 de- grees to the right (to include the effects of coriolis) with a magnitude of drift (in miles/12 hour period) of .003684 x W x W + .282 x W (where W = wind speed in knots) (Morgan, 1 970). This portion of the drift component was to take into account leeway and the Ekman current component. The coefficients of the equation were adjusted over the years. The above coefficients are from the late 1960s. The wind data for the vector addition routine was obtained from the U.S. Navy Me- teorological office at Argentia until the closure of Air Station Argentia in 1 970. After 1 970, the wind data was supplied by the U.S. Navy Fleet Numerical Weather Center (FNWC) in Monterey, the predecessor of the Fleet Nu- merical Oceanographic Center (FNOC). The ocean current information was derived from two sources. Ice Patrol con- ducted hydrographic surveys in the vicinity of the Grand Banks beginning shortly after the inception of Ice Patrol and developed geostro- phiccurrent data using the methods described in Sverdrup et al., 1942. Monthly mean dy- namic heights forthe area of the Grand Banks were developed (Soule, 1 964). The U.S. Navy OceanographicOffice monthly mean charts of sea current were used to provide information for the area outside of that covered by the Ice Patrol mean dynamic height charts. The sea current was vectorially added to the wind com- ponent to predict iceberg drift. With a manual plot method, there was a practical limit to the time available to predict the drift of icebergs upstream of the icebergs closest to the area defining the limit of all known ice. During light iceberg years, it was possible to predict the drift of all of the icebergs reported to Ice Patrol. During a heavy iceberg year, it may have been impractical to predict the drift of all the reported icebergs. The manual plot was updated twice daily. The plot 58 was used by the Ice Patrol personnel to help determine if an iceberg report was a new sighting or a resight of an iceberg already being monitored. Lenczyk (1964) published a method of predicting the deterioration of icebergs that was used by Ice Patrol up until 1983. The method used sea surface temperature and iceberg size as its inputs to predict, in an average sea state, the number of days for an iceberg to melt. The deterioration was done twice weekly and records for each iceberg were kept by hand. The sea surface tempera- ture was obtained from charts prepared by the U.S. Navy and updates provided by ships reporting sea surface temperature directly to Ice Patrol. This deterioration method was used as input by the Ice Patrol officer to decide to remove an iceberg from the active plot. 197110 1979 In 1 971 , Ice Patrol began using a com- puterized version of the manual vector addi- tion routine. The program is described in Morgan (1 971 ). The model area for the com- puterized vector addition routine was selected to cover the area from 40 to 52 degrees North and from 39 to 57 degrees West. At the time of the model creation, it was felt this area would allow modeling of nearly every iceberg that would create a threat to navigation within the area of Ice Patrol's statutory responsibility. A computerized version of the monthly currents field was created from the same data Ice patrol had been using as the input to the manual vector addition method. The current fields were updated by Scobie and Schultz (1976) by incorporating recent survey infor- mation into the monthly means. FNWC provided a computer-readable wind input for the computer model on a one degree latitude by two degree longitude grid covering the model area. Analysis winds along with predicted winds 1 2 hours, 24 hours, and 36 hours into the future were provided. This allowed Ice Patrol to be able to predict iceberg movement for periods up to 36 hours into the future. The computerization of the manual vec- tor addition routine helped eliminate cumula- tive errors associated with hand plotting. The computer also allowed all iceberg reports re- ceived within the model region to have their drift predicted without adding much work load to the Ice Patrol staff. The introduction of the model provided a better tool to determine whether an iceberg sighting report was either a new iceberg or a report of an iceberg already being monitored. This improved ability to model all icebergs and determine if the report was for a new iceberg or not helped improve the accuracy of the estimate made by Ice Patrol of the number of icebergs crossing south of 48 North. Icebergs which were drifted south of 48 North by the model without actually being seen were included in the estimate of icebergs crossing 48 North. 1979 to Present In 1979, the vector addition computer program was replaced by a dynamical bal- ance of forces model (Mountain, 1979). The input procedures, the appearance of the model output, andthe model areadid not change with the model replacement. The winds used as the new model input were supplied by FNOC. The monthly sea current files were combined into a single mean historical current field and used as the current input into the new model (Murray, 1979). In 1981, an addition was made to the model to allow the mean current fieldto be modified by realtime satellite tracked drifter data (Summy and Anderson, 1983). The addition of real time current data allowed the drift prediction model to produce better results. In 1982, a computerized deterioration prediction model was implemented (Ander- son, 1983). The deterioration model allowed the melting of all the icebergs being tracked by IIP to be predicted, not just the icebergs done by hand close to the limits of all known ice. During the active season, sighting re- ports received in the area where no model ocean current data exists (along the coast and in the bays of the Newfoundland coast) are not entered into the model. Only a small percent- age of the icebergs reported in the Avalon Channel (the area just off the east coast of Newfoundland) are entered into the model. Icebergs in this area, although south of 48 59 North, do not effect the limits of the area of iceberg danger. The total number of iceberg sighting reports received and not entered into the model for this area (and therefore the data base) is unknown. Analysis Techniques Of Siaiiting/Drift Data All iceberg sighting data received by Ice Patrol is treated the same regardless of sighting source. After a sighting report is received, Ice Patrol personnel must determine whether the report is for a new iceberg or a resight of an iceberg already reported. The reported position is compared to the predicted positions of previously reported icebergs. The criteria for determining whether a sighting report is a resight or not have changed over the years and also vary by geographic position within the Ice Patrol area and with proximity to the limits of all known ice. The criteria described below are the general prin- ciples used from 1 960 to 1 991 . If the report is in an area known to have variable currents (particularly near the Tail of the Banks), a sighting report within about 30- 40 miles (depending upon when the iceberg was last reported) of the predicted position of a previous report could be considered a resight. Icebergs further from the limits of all known ice are more likely to be resighted, particularly those on the northern portion of the Grand Banks. As the "Limits of all known ice" are approached, a more conservative approach to resights is taken. Unless the sighting report closely approximates the predicted position and size of a previous report, the iceberg is added rather than resighted. This philosophy ensures all of the icebergs near the limits of all known ice are reported in Ice Patrol's prod- ucts. There are four ways icebergs are re- moved from the list of active icebergs being monitored by Ice Patrol. If an Ice Patrol flight overflies the location of an iceberg and the iceberg is not located, the iceberg will be deleted from the active iceberg list. If the iceberg is predicted to have melted, it will be removed from the active list. A more conser- vative approach to removing icebergs because of melt is applied when the iceberg is close to the limits of all known ice. If an iceberg has been on the active list for thirty days without been resighted, it will be removed. If an iceberg is predicted to drift to the east or west of the Ice Patrol area, it will be removed from the list of active icebergs and a note about the last predicted position will be put in the iceberg bulletin sent to shipping. Icebergs are not removed from the ac- tive list when a ship report of no ice in an area is received because the errors associated with the drift prediction could easily have placed the iceberg outside the detection capability of the ship. "Counting" Tlie Icebergs South Of 48 North From 1960 to 1988, the estimate of icebergs crossing south of 48 North was deter- mined by hand counting from the paper records and/or model outputs. The Ice Patrol officer was responsible for determining the estimate of the number of icebergs crossing 48 North , a task that was easier in light ice years than during heavy years. 1960-1970 Atechnician was assigned to keeptrack of the number of iceberg sightings that were reported south of 48 North. Icebergs that were predicted to drift south of 48 North were also included. In heavy ice years, not all of the icebergs reported may have had the manual drift done. The numbers produced by the technician were reviewed by the Ice Patrol officer prior to release. 1970-1988 Forthe computer model years, the tech- nician would review the daily model printouts each month and determine which icebergs had either been sighted or drifted south of 48 North. No differentiation was made between icebergs sighted and those drifted south of 48 North (without actually being seen south of 48 North). For each iceberg south of 48 North, the technician would have to determine how 60 many icebergs that model entry represented. (When IIP received reports with multiple ice- bergs in the same location, only one entry would be made into the model and the number of icebergs that entry represented would be noted in the model input log.) The technician would also ensure that the target number was not included in last month's count. The num- ber of chances for errors within the manual counting scheme increased with the number of icebergs entered into the model. Beginning in 1 982, the computer model used by International Ice Patrol created a file containing the sighting and final drift position foreach sighting entered into the model. Only sighting reports received by Ice Patrol with positions within the bounds of the model (40 to 52 North and 39 to 57 West) were entered into the model. This means all sighting reports after 1 982 outside the bounds of the model are NOT included in the data base. The numberof reports received outside of the model area is estimated to be less than 1 00 peryear with the majority of the reports being north of 52 North. After 1 982, sighting reports received when the model was not being njn are not included in the data base. 1989-1991 Development of a computerized tech- nique to "count" the number of icebergs cross- ing 48 North began in 1 989. This method was used to generate the numbers published in the 1989 to 1991 bulletins. Development was completed in 1 991 . The new technique takes into account the number of icebergs each entry represents and provides a break down by sighted versus drifted but never sighted south of 48 North. The new computerized technique uses the model iceberg sighting history file. This file contains the sighting date and position, and final drift position for each target entered into the model, including resights. The counting program examines all of the entries for each target number that was an iceberg (not a radar or growler) to see if: (1 ) an iceberg entry was sighted south of 48 North or (2) if an entry was drifted south of 48 Nor+h without being sighted south of 48 North. A "Count" Review A summary of the iceberg sightings from the database for the period 1960 to 1981 is shown in Table 1 . Also included in Table 1 is the estimate of the icebergs to have crossed south of 48 North for each year. In comparing the database summary to the published esti- mate of icebergs drifting south of 48 North, some observations can be made. In 1966, Ice Patrol published an esti- mate of zero icebergs drifting south of 48 North yet the database includes 12 iceberg reports representing 1 4 icebergs sighted south of 48 North. No explanation for this observa- tion is offered. In 1969, 1979, 1980, and 1981, the number of icebergs represented by the data- base iceberg sighting reports sighted south of 48 North is less than the published estimate of the number of icebergs drifting south of 48 North. A possible explanation for this obser- vation would be the inclusion in the published estimate of icebergs predicted to have drifted south of 48 North by the prediction scheme usedduringthoseyears.ln1960through1964, the number of icebergs represented by the database sighted south of 48 North is larger than the published estimate of the number of icebergs drifting south of 48 North. This could be accounted for by the resighting of icebergs already reported and regular reconnaissance flights of the same area. The new computerized counting tech- nique was applied to the model iceberg sight- ing history files from 1 982 to 1 991 . A summary of this application is in Table 2. A more detailed break down by year is included in Attachment 2. For the period 1982 to 1984, the sighting source was not entered into the model. For the period 1982 to 1985, the number of icebergs each entry represented was not entered into the model. The new computerized counting technique was applied consistently to all of the data. The results show differences with the previous methods used. The computerized technique is be- lieved to be a more accurate reflection of the icebergs WHICH IIP INCLUDED IN ITS MODEL that were either sighted south of 48 North or drifted south of 48 North. 61 0) n CO I- 00 I o to (0 E E CO w CO B Q D) C cn CD o CT3 Q_ 0) o 62 1 0) Oi-^ CO r^oincDcoo-'-ajr^incoi^i^cD'^T-cvjincvjoco ' mat iftin 481 LO T-cvjcucor^ ■^-i-LOoor^oo'^oooLOcvjr^mcMcD C\J ■•-■.-co ■^cj mooco->-T- 1- « Q o UJ CO :£ ■D P 5 -cj>c\jco->-ocM'^c\j ■<- sent lepo of 41 CO ^ o ••- X— 0) n 0) _o O) CO ^ r^ cDCDf^LOTi-cNjcDOcDCDCDr^'^r^cjJcDoomcDcocn Iceber Report h of 481 in COOCOCOCO-.-ir)QOCOCOOOLO-.--^-.-CDC\J'^C\J 1- T— c\jcDT-r^cM T-Tf -r- oi T- t-- cr> y- - CvJ T- CVJ CJ C\J Z3 O CO bergs* 5ented leports ■<;t i-r^r^iocDoocoTj-r^r^cDcvjincDcocoLncvjcvjoo 00 ■•-LOocoLOi-ooincDocDCDioooi-'^oocor^ocvj ■^ oom-i-cjicor^r^cDcoooooinr^cDinoomocoi--^ C\J c\jcot-ioc\Jt-cocococm m CO ^ t- 0) 0) cc O 2- ^ — Q. > cu -Q a: * D) CO r^ oocoLO'^Lf)oocMoi/)cx)LnT-o3cocDcoodo-'-T-h~ CO cDr^oor^c350cooj-t-cDcocDoc7)r^ooocor^oc\j 0) V; O 00 cjcomc\jT--t-cxjcnoocoh-cncoco-^coir)ocoi--.- ^ -c a 1 — C\JC\J ■«tf-i-C\JC\J-.-i- -^co-^ 1- CD C3) 0) o c/D DC k_ o ■i-cMco-^Lncor^oocno->-cocoT}-Locor~-QOCDOT- CC CD cDCDcDCDCDcocDCDC£>r~--r--h-.r^r^r--r^r^r^h~oooo 0> > V CD CJ)0>(3>CDCJl(DCJ>CJ)CJiC7)CDCn(J)CDCT)CJ)Cn(JlCJ)CDCn / / CO D. 0) CJ 0) CO SI o ■^^ r^ o o CO c CO 0) C3) O >» CD ^ E 0) 2 o B — o "TO ^ ^ CO E .E 0 5= CO CO D)CQ .E o 3 C "°« 03 -^ ^ 1= ■^■^ CO > P3 0) CO .y CO -n ^ 1 ^ E ^ °^ 10 ■§ CO o 0) £ 1_ •— ^— • „ 0) © 0)^ CO ^ 0) CO .c c I- 2 *.. "cO B 05 O CI. ZO Summary The IIP iceberg sighting database is not a complete set of all icebergs actually drifting south of 48 North each year. A detailed description of the database contents is con- tained in Attachment 3. Although not com- plete, the Ice Patrol database does represent the most complete and continuous iceberg data set available. Over the past 30 years, numerous changes have occurred that effected Ice Patrol's ability to estimate the number of ice- bergs crossing 48 North. As the people at Ice Patrol changed, the methods used to accom- plish manual tasks changed (Examples: de- termining if a report is a resight of an iceberg already being drifted and performing the an- nual counts). Technological advances af- fected, and continue to affect, Ice Patrol's operations and thus the gathering and pro- cessing of data. Bursts of activity in the Ice Patrol area by outside concerns (oil industry, fishing industry, and government agencies) provide increases in the volume of data to be processed. All of these factors have signifi- cantly affected the annual estimate of icebergs crossing 48 North and make difficult direct year to year comparisons. Several efforts have been made by a variety of authors to use different methods to classify/rank the severity of a year with regards to icebergs. Although these methods are all based on the estimates of icebergs crossing 48 North, the methods do not use definitive numbers as a measure. In 1987, Ice Patrol began classifying season severity (Alfultis, 1987). Ice seasons are classified as either light (less than 300 icebergs estimated south of 48 North), intermediate (between 300 and 600 icebergs estimated south of 48 North), heavy (between 600 and 900 icebergs esti- mated south of 48 North), or extreme (more than 900 icebergs estimated south of 48 North). Prior to 1 987, the ice seasons were classified by Ice Patrol as light, normal, or heavy by comparing the annual estimate of the number of icebergs crossing 48 North to the long term average. Davidson et al. (1986) describe a severity ranking systemthey used in their work with the data set. This system relies on rela- tive comparison of seasons. Hopefully, this paper has provided enough insight into the Ice Patrol iceberg database to allow it to be used within its collection constraints by others. Acknowledgements I would like to thankthe following people who were a part of Ice Patrol's past for review- ing this paper and helping describe the tech- niques that were used. The years the individu- als served with Ice Patrol follow their names: Rudy Lenczyk (1962-1965); John E. Murray (1 965-1 968);CharlesW. Morgan (1969-1971); James R. Kelly (1 969-1 970); David W. Crowell (1972-1975); Steven R. Osmer (1974-1975 and 1 987-1 990); Brian Kingsbury (1 979-1 981 ); John J. 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