aircraft is flown at 8000 ft 

 (2440 m), the radar maps a 50 km 

 wide swath on each side of the 

 aircraft with a blind spot 5 km 

 wide directly under the aircraft. 

 Both antennas are vertically 

 polarized. 



Several different flight patterns 

 were used during the survey. The 

 intent of the various patterns was 

 to obtain several different direc- 

 tions of look relative to the wind, in 

 addition to looking at the thermal 

 fronts from various ranges. 



RESULTS 



The following sections describe 

 some of the data that constitute 

 the surtace-truth for the SLAR 

 interpretation experiment. The 

 radar data are currently being 

 analyzed. The surface-truth data 

 presented here are limited to the 

 first phase because it is the more 

 complete of the two data sets and 

 the first to be analyzed. 



Hydrography 



Figure D-2 shows the surface 

 temperature on the first phase 

 hydrography. A small, warm-core 

 eddy, centered at 43-50N, 48-20W 

 and with a diameter of about 65 

 km dominates the temperature 

 field in survey area. North of the 

 eddy is cold water (< 3°C) of 

 Labrador Current origin, while 

 warm water (> 12°C) from the 

 North Atlantic Current is evident in 



the southeastern part of the study 

 area. Although it appears from the 

 surface temperature distribution 

 that the eddy was separate from 

 the North Atlantic Current, their 

 proximity makes it likely that they 

 were interacting. 



The greatest surface temperature 

 gradient, about 8°C, is located at 

 the northern boundary between 

 the eddy and the Labrador Cur- 

 rent. Over an 18 km distance, the 

 surface temperature changes from 

 less than 3°C to greater than 

 10°C. It is in this region that the 

 SLAR is most likely to detect a 

 difference in radar return. 



A vertical temperature section 

 (Figure D-3) along the center of 

 the 5 north-south transects (A-B 

 on Figure D-2) shows that the 

 10°C isotherm extends to about 

 160 m. It also shows the locations 

 where three of the drifting buoys 

 were deployed. Buoy 4536 was 

 deployed in 13°C water near the 

 center of the eddy. Buoy 4547 

 was deployed in 3-4°C water north 

 of the eddy. Finally, buoy 451 1 

 was deployed near the eddy's 

 northern edge. The center of the 

 drogues for all of the buoys is at ~ 

 58 m. 



102 



