NO A A PROFESSIONAL PAPER 11 



Valley. In May, the minimum grounded only along the 

 New Jersey coast, but in June it also grounded along Long 

 Island (figs. 2-25 and 2-26). In May it was closer to the 

 bottom off New Jersey than off Long Island but the reverse 

 was true in June. 



HURRICANE BELLE 



The seasonal progression of stratification in New York 

 Bight was interrupted on August 10 by the northward 

 passage of hurricane Belle through the area. Belle had 26- 

 to 3()-m/s winds and a forward speed of 10 to 30 m/s during 

 this period (NOAA 1977). Immediately preceding (Au- 

 gust 8) and following (August 11) the hurricane. Sandy 

 Hook Laboratory personnel made XBT observations at 

 three stations along 39° 30'N latitude off Beach Haven 

 Inlet, N.J., in the vicinity of XWCC stations 40 and 41 

 (fig. 2-1). The three sites were occupied again on August 

 16. Bottom oxygen values were determined on all stations, 

 so an evaluation of return to prehurricane conditions can 

 be made. 



The XBT traces for the three sites are shown in figure 

 2-27. Before hurricane Belle, surface temperatures were 

 between 22° and 23° C. Bottom temperatures were near 

 11° C. A very strong thermocline existed from a depth of 

 5 m at the inshore and offshore stations to a depth of 12 

 m at the middle station. After hurricane Belle, on August 

 11, surface temperatures had been lowered to between 

 18° and 19.5° C; bottom temperatures had been raised 

 6° C at the inshore station, 4° C at the middle station, but 

 only 2° C at the station farthest offshore. The thermocline 

 was markedly reduced at the inshore station, less so at the 

 middle station, but was still relatively strong at the off- 

 shore station. 



Five days later, on August 16, surface waters had 

 warmed by 1.5° to 3.5° C, to over 21° C at all three sites. 

 Greater warming was evident at the middle station. Bot- 

 tom waters had cooled about 1.4° C, and a strong ther- 

 mocline was beginning to be reestablished. Though bot- 

 tom temperatures were nearly the same at all three sites 

 before the hurricane, they exhibited a negative, offshore 

 gradient of 2° to 3° C between adjacent sites at the two 

 reoccupations following the hurricane. The colder bottom 

 waters could only result from water being advected to 

 these sites from an outside source, probably from offshore 

 because the coldest bottom water was at the station far- 

 thest offshore. Bottom oxygen measurements for the three 

 XBT stations showed an increase from zero or near zero 

 before the hurricane to 2.0 to 3.5 ml/I immediately after. 

 Measurements were again zero or near zero 6 days later. 



BOTTOM ENVIRONMENT IN SEPTEMBER 



The Researcher September 11-17 stations, and the Al- 

 batross IV August 24 to September 9 stations in the same 



AUGUST 1976 



TEMPERATURE (°C) 



FIGURE 2-27, — Effect of hurricane Belle on temperature structure. 

 XBT station locations: shoreward (top), intermediate (middle), and 

 seaward (bottom) stations. Dates of observations: August 8 and 9 

 (before). August 11 (immediately after), and August 16 (6 days 

 later). 



area and southward along the New Jersey shelf to Cape 

 May, provide complete and relatively detailed data for 

 the area of oxygen depletion. 



Bottom-water temperatures (fig. 2-28) were variable. 

 The coldest water was observed in the Hudson Shelf Val- 

 ley and in a band along the outer shelf. The offshore band 

 has been named the "cold pool" (Bigelow 1933: Beardsley 

 et al. 1976). Bottom waters generally were warmer off 

 New Jersey than off Long Island. They were warmest off 

 the Hudson-Raritan estuary and extended eastward a 

 short distance along the Long Island shore. The salinity 

 pattern (fig. 2-29) was much more regular. Relatively 

 fresh water was observed off the estuary and along the 

 coasts. The resulting density distribution also was very 

 regular. Lowest density values were off the western Long 

 Island shore, but bottom waters had lower densities on 

 the New Jersey shelf than on the Long Island shelf. Values 

 of D.O. (fig. 2-30) associated with these distributions 

 were almost as irregular as the temperature, but show a 

 pattern consistent with that reported previously (Steimle 

 1977). Two regions had oxygen concentrations less than 



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