HYDROGRAPHY OF THE MARINE WATERS 



33 



Temperatures in the Sounds, etc. 



The only continuous temperature records that have come to my attention 

 for the inland waters are those taken at the Fish & Wildlife Service Labora- 

 tory located in Beaufort Harbor. In Figure 13 the air temperature at this 

 station is indicated and the individual surface temperature records on ebb 

 and flood tides are plotted. This shows that water temperature ( i ) is essen- 

 tially the same on ebb and flood tides, (2) corresponds closely to the air 

 temperature through the year, and (3) is usually slightly lower than air 

 temperature. Since the offshore waters show much less seasonal change 

 (Figure 11), it is apparent that it is the atmosphere and the factors which 

 heat the atmosphere,^- and not oceanic waters that exert the major influence 

 on the harbor water temperature. From the geography of the region it is also 

 apparent that most of the sounds and other inland waters would be similarly 

 influenced by atmospheric temperatures; consequently Figure 14 has been 

 prepared to present the average monthly air temperatures at coastal weather 

 stations and to imply thereby the water temperatures in the inland waters. 

 For considering digressions from long-term averages, reference should be 

 made to Table 10, which presents the records for a period of seventy-two 

 years at the centrally located Hatteras station. 



TABLE 7 



Monthly Maximum and Minimum Water Temperatures (° F) at Fivers Island, 

 1924-1928, Based on One Reading Daily* 



♦From Outsell (1931). 



12. Of course the offshore waters are among the factors governing the atmospheric tempera- 

 ture along the coast and in this way they indirectly influence the inland waters. 



