158 



in sea-surface temperature and the resulting increase in total energy exchange; 

 the eye and wall cloud of the hurricane became better defined, and the central 

 pressure dropped 7 ni-ti in 7 hours. The intensification continued as the storm's 

 track lay over the axis of the warm water stream. 



Dunn and Miller (1960) indicate that in the absence of mi d-tropo spheric 

 ventilation, the vertical temperature structure of the hurricane core is 

 determined by the heat and moisture content of the subcloud air which, in turn, 

 is closely related to the temperatures of the underlying water surfaces. For 

 instance, hurricane Janet (1955) deepened over warm water, and hurricane 

 Carrie (1957) weakened over cool water; however, the rate of change in hur- 

 ricane intensity depends upon the length of time it takes a hurricane to 

 traverse a particular water mass . 



Riehl (1963) points out that a relationship exists between the develop- 

 ment of hurricanes and the small anomalies of local temperatures . Perlroth 

 (1962) exemplifies this relationship between hurricane intensity and the air- 

 sea interaction in a comprehensive study of hurricane Esther (1961). 



The sea-surface temperature and hurricane -pressure relationship is 

 illustrated in Figure 6. For this relationship to be coincident, the sea- 

 surface temperature pattern during the 10-day period must have remained con- 

 servative . As shown in Figure 5j when the hurricane eye and wall cloud entered 

 part of the cold shelf water on October 25, a marked decrease in intensity 

 occurred. The central pressure of 976 mb was observed at October 25, 1200 UT, 

 while by October 25, l859 UT, -a reading of 985 mb was obtained. The storm 

 then turned sharply to the east-northeast and once more entered the axis of 

 the Gulf Stream. The central pressure of hurricane Ginny again began to 

 deepen and by October 26, 0359 UT, reached 983 mb. On October 26, the hur- 

 ricane appeared to be headed for Wilmington, N. C . Once again, as the eye 

 passed over the cold shelf water, a notable decrease in intensity was observed. 

 Aircraft reconnaissance indicated that the wall cloud was becoming diffuse, 

 and a central pressure reading of 988 mb was observed. These observations 

 indicate that the storm structure responds spontaneously to the total energy 

 f l\ix from sea to air in the vicinity of the hurricane eye .' 



On October 28, the steering of hurricane Ginny became influenced by a 

 deepening polar trough forming along the east coast, consequently causing a 

 rapid acceleration of the hurricane to the northeast. Because of the influence 

 of this trough, correlations of hurricane intensity and sea-surface tempera- 

 ture were not determined. The hurricane reached the majcimum intensity east 

 of New England as it accelerated rapidly north-northeastward. 



CONCLUSIONS 



The results of this study imply that a relationship exists between 

 hurricane intensity and the total energy flux from sea to air. The evidence 

 produced in this and other studies brings out the significance of this 

 relationship. 



