Fluctuations 143 



A good check on these ideas could be obtained by means of potential 

 measurements on a middle-Caribbean cable such as the one between 

 Cura9ao and Santo Domingo. The time lag should be about half that 

 observed in the Florida Straits. 



It is important to be aware that these remarks about causes of fluctua- 

 tions of the Florida Current are only speculations and ideas, not proven 

 theories in the usual physical sense. 



That such facile speculations may be treacherous is illustrated by certain 

 occurrences that have been observed. In January, 1955, there was an 

 exceptionally intense and widespread month-long breakdo^Ti of the 

 Bermuda-Azores atmospheric high-pressure cell, and the northern fringes 

 of the trades disappeared. This meteorological event was accompanied by 

 a decrease in the transport of water through the Florida Straits — a singular 

 instance of complete reversal of the simple explanation discussed above. 



SEASONAL FLUCTUATIONS OF THE GULF STREAM 

 NORTHEAST OF CAPE HATTERAS 



In the previous chapters in which we discussed the details of single cross 

 sections of the Gulf Stream we were on fairly solid observational ground. 

 In Chapter IX, on meanders, the dangers of picking one of many different 

 possible interpretations of the data, and ignoring the other interpretations, 

 arose. There was an uncomfortable feeUng of engaging more with a 

 creation of our own minds than with a fact of nature. As we now proceed 

 to discuss the fluctuations of the Gulf Stream, we are even more apt to find 

 ourselves pursuing a -will-o'-the-wisp. Although we do know something 

 about seasonal changes in the shallow wind-drift currents in the upper 

 100 m. of the ocean, and although we do have fairly adequate data, from 

 tide gauges and the submarine cable, for a study of the Florida Current, we 

 know virtually nothing about changes in the transport of the Gulf Stream 

 itself. With these words of warning, we may now examine what little 

 material there is at hand. 



There has never been a cruise which failed to find the Gulf Stream between 

 the United States and Bermuda. It is quite clearly a permanent feature. 

 But are the position and transport of the Gulf Stream entirely independent of 

 the seasonal fluctuations in the strength and position of the wind system ? 



The pilot charts which are based on hundreds of ship reports on file 

 with the United States Navy Hydrographic Office indicate the presence of 

 seasonal changes in the surface currents. Fuglister (1951a) has prepared 

 a summary of these surface -current data in miles per day. They are pre- 

 sented in fig. 74. The curves for the Florida Current off Miami, the Florida 

 Current southwest of Cape Hatteras, and the Gulf Stream northeast of 



