88* W 



GULF 



F 



M E X I C 



I 



TERREBONNE BAY LINE 



E 23 E22 E46 



BARATARIA BAY LINE 

 STATIONS E44 E25 E26 E27 j|,.j.Ea3 



-28'C 



KM. 



Figure 47.— Station lines occupied aboard the M/V Gus III before and after Hurricane Betsy. The 

 hurricane eye crossed the coast over Barataria Bay. Note the subsidence of the thermocline 

 after the hurricane and the wedge of warm water against the shore. 



of the thermocline was bounded by the 26° C. 

 isotherm. Beyond 130 km., the isotherm at 

 the top of the thermocline was either 27° C. 

 or 28° C, but in all areas it was at least 1° C. 

 less them in August. Little indication of 

 brackish water appeared above the thermo- 

 cline. 



Ten days after Hurricane Betsy had crossed 

 the northern shelf of the Gulf of Mexico, the 

 depth to the thermocline beneath and to the 

 east of the path of the storm lay at depths 

 between 40 and 50 m. To the west of the 

 path, the top of the thermocline was between 

 20 and 50 m. In all waters except those 

 immediately beneath the path of the storm, 

 the top of the thermocline was bounded by 

 the 27° C. isotherm. Beneath the eye's path. 



26° C. continued to mark the top. Brackish 

 water had returned to the surface layers 

 and was evident to the west of the mouth 

 of the Mississippi River (fig. 48; note layers 

 with temperature inversion). 



Clearly, the hurricane profoundly modified 

 the waters over the northern shelf of the 

 Gulf. The typical surface waters next to 

 shore were removed and replaced by waters 

 with ocecinic characteristics. The influence 

 of the hurricane extended to the greatest 

 depths of the Continental Shelf (75 m.) so 

 that water temperatures on the shelf floor were 

 as much as 6° C. warmer sifter the storm 

 than before (fig. 49). Upwelling in the upper 

 30 m. of the water column was evident at 

 distances of about 90 km, either side of the 



41 



