GULF OF MEXICO EDDY MONITORING 
FOR OFFSHORE OPERATIONS 
VALID DATES: 11/6-13/85 
IMPORTANT OBSERVATIONS: Narrowing of Loop Current 
neck indicative of potential eddy detachment in the next —_-- 
few weeks. 
GALVESTON . 
BROWNSVILLE LOOP 
CURRENT 
IIG 
wath 
eye 
cay 
44 
ARROWS INDICATE DIRECTION OF FLOW 
DRILLING AND PLATFORM SITES: G C = GREEN CANYON 
SYNOPSIS OF FEATURES 
EDDY ID CENTER MOTION 
LAT LONG TO SPEED 
85A 25.3 92.8 W 2.5 
n.mi./day 
VELOCITY 
1 to 2 knots 
DRILLING AND PLATFORM SITES 
SITE EDDY POTENTIAL 
START DURATION 
GC None at 
this time 
MAX EXPECTED 
Less than 1 knot 
An example of thermal-infrared imagery un- 
der these conditions is given in Figure 9. In this 
TIROS channel-4 (11 um) image, only the north- 
ern boundary of the Loop Current can be ob- 
served in the northeastern Gulf. In contrast, 
Figure 10 shows the CZCS imagery taken on the 
same day.° In this figure, regions with high chlo- 
rophyll concentrations are denoted by the light- 
est colors and those with low concentrations by 
darker colors. Clouds are shown in black. 
Many ocean features are clearly observable in 
this imagery. For instance, the continuous 
boundary of the Loop Current can be seen as it 
This image was processed to eliminate the atmospheric com- 
ponent using a Principal Component technique (Holyer and 
LaViolette 1984), although similar results can be obtained us- 
ing the more typical Gordon subtraction atmospheric removal 
technique. 
MAXIMUM SURFACE 
SURFACE VELOCITY 
Figure 8. Typical summary of eddy 
and current-jet locations used by 
the offshore oil exploration and 
production industry. (Courtesy J. 
Haustein) 
enters through the Yucatan Channel and mean- 
ders to its eastern extent. Two eddies can be 
observed in the western Gulf, and, within the 
shelf waters off Louisiana, Mississippi, Alabama, 
and Florida, the mixing patterns of these waters 
can be identified as significant fronts. 
It should be noted that the imagery in Figure 
10 has been processed to the end of the swath 
in the western Gulf. Although these data can- 
not be subjected to quantitative analysis, the 
ocean's features clearly can be seen at the out- 
ward extent of the CZCS's 40° scan, document- 
ing that useful data can be obtained from CZCS 
imagery at scan angles greater than 30° from 
nadir. Despite the fact that a scan angle of 58° 
will be required to provide daily coverage from 
the Landsat-6 orbital altitude, the value of hav- 
ing daily coverage is enormous, even if some of 
the data can only be interpreted qualitatively. 
COMMERCIAL AND OPERATIONAL USERS' PANEL 
13 
