FISHERY BULLETIN: VOL. 73, NO. 2 



eastern two-thirds of the United States. The con- 

 trast between this cold air and the air heated by 

 the Gulf of Mexico and western Atlantic waters 

 led to baroclinic deepening of coastal storms. In 

 these regions of cyclonic activity, vertical advec- 

 tion may have caused some cooling through diver- 

 gence of surface water and consequent local up- 

 welling. Leipper (1967) has shown that hurricane 

 Hilda, passing over the Gulf of Mexico in the early 

 fall of 1964, indeed did cause significant cooling of 

 surface waters through upwelling processes. 

 However, the large area covered by anomalously 

 low sea-surface temperatures in the winter of 

 1957-58, and other factors such as the frequent cold 

 outbreaks over the entire eastern seaboard and 

 the fact that the sea temperature anomalies ap- 

 peared to occur over large areas contemporaneous 

 with the overflow of cold air, suggests that the 

 high rate of sea surface cooling was due to 

 anomalously high loss of heat through evaporation 

 and conduction of sensible heat. 



To test this supposition formulae for calculation 

 of the heat exchange at the air-sea interface have 

 been employed. Laevastu (1965), Seckel (1962) and 



many others have provided these formulae. In this 

 study the procedures for calculation of the energy 

 exchange as presented by Johnson et al. (1965) are 

 used. It is not the intent here to review the ac- 

 curacy of the various techniques for estimating 

 air-sea energy exchange. Because of the possible 

 inaccuracies of input data and of the formulae, the 

 exchange values should be viewed with caution 

 and should be considered only as relative indices of 

 the magnitude of energy flux at the air-sea inter- 

 face. They appear, however, to be sufl'iciently ac- 

 curate to permit detection of large-scale seasonal 

 and nonseasonal variations. 



The equation for the heat exchange at the air- 

 sea interface is 



Qt = Qi- Qr-Qb- Qe- Qh 

 where: 



Qt ~ Net heat gained or lost at the sea surface 

 Qj = Incident solar radiation corrected for cloud 



cover 

 Qfi = Reflected radiation 

 Qg = Back radiation 

 Qe = Evaporation 

 Qff = Conduction of sensible heat. 



1948 

 +1.0 



1950 



1952 



1954 



1956 



YEAR 

 1958 



1960 



1962 



1964 



1966 



0.0 



e 

 U 



< 

 X 



u 



Ul 





UJ 



u 



oe 



M 



-1.0 



— n — 



/ \ 



/ \ 



/ \ 



•SEA-SURFACE TEMPERATURE CHANGE 

 -NET HEAT EXCHANGE 



+100 



-100 



-200 



< 



CM 



o 



>^ 

 CO 



— 



O 



-I 

 < 



-300 



z 



I 

 o 



X 



< 



UJ 



I 



-400 



-500 



1950 



1952 



1954 



1956 1958 



YEAR 



1960 



1962 



1964 



1966 



Figure 4.-Relation between net heat exchange at air-sea boundary and sea-surface temperature change winters of 1948-67 in the 



area bounded by long. 80° to 90°W and lat. 25° to 30°N. 



I 



310 



