2.2.1 Mapping 



The mapping of the Argo Merchant spill was more extensive than in the 

 case of any previous spill because of the overall concern with the immediate 

 location and potential impact of this particular spill, and because of the 

 SOR Team's goal of gaining information that could be used to improve predic- 

 tive modeling. The mapping was a coordinated effort involving several tech- 

 niques (visual, IR, and photographic) and a number of organizations (NOAA, 

 USCG, ADEC5 AMSI, NASA, EPA and BLM) , with J. Deaver of the USCG Oceano- 

 graphic Unit being the principal producer of daily oil-slick maps. In addi- 

 tion to the formal imagery, videotapes and photographs of the spill were 

 taken by the USCG and several representatives of the news media. Most of 

 these records have been identified and are being collected, collated, and 

 summarized by the SOR Team. Interpretation of these data and their ultimate 

 use in improving predictive modeling will constitute an important part of the 

 follow-on research effort. 



Among the initial results of the mapping effort was the description of 

 the formation and movement of large "pancakes" (large, thick oil slicks), 

 which maintain their cohesiveness and integrity for long periods of time. 

 There has been considerable interest in the motion and dispersion of such 

 pancakes. Experience gained in an earlier spill in the Florida Keys indi- 

 cated that they are up to 6 inches thick and that the volume of oil on the 

 surface can be quite substantial. When several pancakes 50 to 90 feet in 

 diameter were spotted on the 5th day of the Argo Merchant spill, an effort 

 was begun to describe this phenomenon more fully and to parameterize the 

 process for modeling purposes. On Christmas Day, a 450-foot by 760-foot 

 pancake, estimated to contain the order of 1/2 million gallons of oil, was 

 found (Appendix III, Photographs 37 and 38). On December 31, NOAA and USCG 

 placed a satellite-tracked buoy on this pancake, and the buoy's position is 

 being constantly tracked by NASA Goddard Space Flight Center via the Nimbus-F 

 satellite (see Section 2.2.3). 



Oil-slick maps of good quality were obtained on most flights in spite of 

 bad weather (Figure 2-2) . Good IR data were obtained less often because of 

 technical problems. The complete set of available maps, up to January 7, 

 1977, are contained in Appendix IV. These maps are tracings by K. Kidwell of 

 EDS, NOAA, of the flight maps prepared on the scene by J. Deaver of the USCG 

 Oceanographic Unit on oil survey flights for the Federal On-Scene Coordin- 

 ator's operational use. They show actual oil sightings, and include an 

 interpretation of oil distribution based on the flight tracks. All maps to 

 date show the flight tracks; the extent, nature, and concentration of oil; 

 and, when available, surface temperature data. Oil is presented at approxi- 

 mately three contour levels: (1) threshold - light; (2) light - moderate; 

 and (3) moderate - heavy. 



Spot estimates of percentage of surface area covered by oil pancakes are 

 also given. These numbers are derived from visual observations and, as 

 indicated above, are only rough estimates and tend to be somewhat high (pos- 

 sibly by a factor of 2 to 10) . Included also are estimates of the size of 

 pancakes, marine mammal sightings (see Section 4.3, and Photograph 28, Appen- 

 dix III) and miscellaneous notes. Sea surface temperatures are depicted, 



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