waters appear along the path of the hurricane, 23 water appearing where 

 temperatures of 29 had been observed. The cold band along the Gulf Coast 

 in shallow water is probably not a part of this upwelling pattern, but is 

 in part due to the fact that the time interval between observations in this 

 area before and after HILDA was 2k days compared to a time interval of less 

 than one-half that for the other data. Also, northerly winds in October 

 probably caused considerable cooling and mixing in these shallow waters. 



Figure 7 shows the pattern of temperature change between Figures 2 and 

 5. The climatic atlases indicate a normal seasonal change of less than one 

 and one-half degrees per month at this time. Thus, the change brought about 

 by hurricane HILDA appears to be some 5° in excess of this . 



To illustrate the depth of isotherms along the section where winds had 

 been highest, 150 mph, Figure 8 was prepared. Since the path of the ship 

 was deflected from a straight line by currents, the section was drawn along 

 a straight line determined by the observations on the western end and by 

 projecting on to this line in the eastern extent the positions of stations 

 near it. The portion of the section based upon these projected stations is 

 indicated by dashed lines for the isotherms . Several features of the section 

 may be significant. The warm surface waters have been pushed to the' left 

 and to the right. A strengthening of the thermocline is indicated by the 

 closer spacing of several of the isotherms separating these uniform warm 

 water bodies from the upwelled water. The isotherms seem to rise rapidly 

 on both sides of the hurricane and the coldest water at the surface appears 

 slightly west of the hurricane path. The warm surface layer is deeper at 

 the eastern end of the section. 



Salinities were obtained to a depth of 125 meters and these, together 

 with temperature values, permit the computation of the density anomaly 

 Sigma t. In Figure 9, lines of equal value of sigma t are plotted against 

 depth and distance . The shallowest depth of the more dense water is noted 

 at the hurricane path. Near the surface, as shown by the constant values of 

 Sigma t, is a layer of mixed water. Proceeding both to the east and the west 

 from the path of HILDA, the depth of this mixed layer increases to a distance 

 approximately 100 miles from the path. 



The temperature structure across section C may be indicated in a 

 different manner by copying the temperature depth traces from bathythermograms . 

 In Figure 10, the BT's from section C, as well as those from the other sections 

 surveyed on the cruise of the GQS III, are shown. Water warmer than 25° is 

 indicated by the crosshatched areas . All of this water is seen to lie away 

 from the path to the east and west. This water is well mixed, the mixing 

 apparently having been caused by the hurricane winds and by the heat loss to 

 the atmosphere which lowered the temperatures of the whole water layer from 

 29 - 30° to 27 - 28°. 



The coldest water is that near the path of the hurricane. The BT's 

 in this sector do not show the surface isothermal layers characteristic of 

 surface cooling and mixing but rather have the rounded characteristic which 



