205 

 The cruises of the R/v EXDALGO in I96I were certainly "cruises of 

 opportunity, " for the extent and magnitude of changes in the waters following 

 a hurricane passage were imknown. Nevertheless, the temperature profile 

 obtained on September 15, I96I ( Figure 8), is quite similar to those from 

 data gathered in 196^4-. The "stovepipe" effect beneath the "eye position" 

 is easily noted, as is the depression of the thermocline on either side. 

 It would appear that Leipper's analysis is correct; that the warmer surface 

 water was transported from the areas of the "eye" to lie in "trough" along 

 the borders of the "eye track, " and that the removal of the surface water 

 beneath the "eye" developed a divergence which resulted in the upwelling 

 of deeper and cooler water. 



One recognizes also, as from the data presented by Leipper, that the 

 isotherms below the thermocline were at lesser depths following hurricane 

 Carla than before (compared Figures 7 and 8). This is the case at least to 

 the depths measured; i.e., about 230 meters . However, the configuration of 

 the isotherms below 100 meters (perhaps even 75 meters) on September 15, 

 was nearly identical to that existing before the hurricane. It was strictly 

 fortuitous that the path of hurricane Carla crossed the southern border of 

 the western Gulf eddy. Thus, the configuration of the isotherms below the 

 thermocline existed before the hurricane and clearly was not altered as the 

 result of any reaction to the storm. 



Water temperatures collected in the northwest Gulf in October I961 

 differed from those in the north-central Gulf in October 1964. In only the 

 shallow nearshore waters in the north- central Gulf wwre there temperature 

 inversions, whereas deep inversions were widespread in the northwest Gulf 

 after Carla ( Figure 3) . In each case, the inversions occurred only where 

 low salinity water made up the surface layer. 



Hurricane Hilda travelled over Gulf waters of normal salinity (@ 36.00 

 per mil) throughout most of its course. Hurricane Carla, on the other hand, 

 travelled over waters which had surface salinities of near 3O.OO per mil. 

 Thus, the water temperatures resulting from the two hurricanes differed sig- 

 nificantly, and any comparison must be subjective . 



It is unlikely that the temperature inversions which were measured in 

 1961 can have resulted from any mechanism other than cooling; i.e., heat 

 loss. Upwelling does not produce such vertical temperature distributions. 

 An introduction of cool, low-salinity water could allow inversions similar 

 to those observed to develop. However, the source of low-salinity water is 

 the estuarine system of the Texas coast which, during the later summer, 

 contains water with temperatures of 28°-32°C. Furthermore, and as discussed 

 by Leipper (this volume), the wind field aroimd the hurricanes develops a 

 wind drift (in these cases, storm surges) which drives water into, rather 

 than out of, the lagoons and estuaries. 



Considering, then, that the inversions represent a certain amount of 

 heat loss from the waters, the magnitude and depth of the inversions could 

 be controlled by (l) the thickness and salinity difference of the surface 



