B-5, TEMPERATORE 



Ntonercms observations were taken by the Karragansett Marine 

 Laboratory of water teniperatures in Narragansett Bay, Surface 

 temperatures observed at the head and mouth of the bay in Feb- 

 ruary 1956 showed no variation, being constant at 36oF, BottoB 

 tenqseratures, however, were recorded at 36°? at the head of the 

 bay and 3U^F at the south. From these observations, it can be 

 noted that the tempera tiire at the surface was the same as at 

 -t^e bott<»D in shallow water, but varied about 2^F for deep water. 

 Tests that were made in April and June 1956, however, showed 

 much greater horizontal and vertical variations (see Table B-2). 



Temperature observations were made in March 1956 near New- 

 port during a complete tidal cycle. Siirface tonperatures 

 remained constant at about 36oF. The average water temperature 

 at the bottom was the same, with a maximum occurring about 1 

 hour after high tide (UOoF) and a minimum about 3 hours after 

 low tide (33*'F), It is believed that these extremes are due 

 to hot and cold eddy currents, 



B-6. SALINITT 



The results of observations made by the Narragansett Marine 

 Laboratory indicate that the salinity over much of Narragansett 

 Bay Is generally high. This is attributed to the relatively 

 small quantity of fresh water entering the bay from the Providence 

 and Taunton Rivers, and to the fact that this fresh water remains 

 on the surface until it is gradually absorbed near the middle of 

 the bay. In fact, the salinities In the region tron the southern 

 end of Prudence Island to the mouth of the bay are virtually con- 

 stant with depth. An analysis of the observations made by the 

 Narragansett Marine Laboratory shows that the salinity of the 

 surface water at the head of the bay is less than at the mouth. 

 This is particularly noticeable around April, and Is undoubtedly 

 due to the heavy spring runoff from the rivers. The bottom 

 salinities for the entire bay, on the other hand, are relatively 

 constant throughout the year (see Table B-2). 



During tidal cycle observations in March 1956, salinity 

 observations showed the effect of the tidal action and the presence 

 of the less dense fresh water on the surface. The most pronounced 

 differences between top and bottom salinities occvanred shortly 

 after slack water. After slack before ebb the surface salinities 

 dropped more rapidly than the bottom salinities, lAereas after 

 slack before flood the bottom salinities increased more rapidly 

 than the surface salinities. Table B-2 also contains the recorded 

 data on salinity for the full tidal cycle on March 26, 1956 in the 

 lower East Passage. 



B-3 



