3 Physical and Coastal Processes 



Climate 



The climate of Long Island is characterized by mild winters and relatively cool summers. 

 Extreme fluctuations of temperature are rare due to the moderating effects of the Atlantic Ocean. 

 The mean annual temperature in the project area is approximately 10°C (50°F). The coldest 

 months (January and February) average about -1°C, while the warmest month (July) averages 

 21°C. Extreme temperatures range from about -23°C to 38°C. The average annual precipitation 

 is approximately 1 14 cm, with lower amounts in the summer months (Moffatt & Nichol 1996). 



Tides 



Tides on the south shore of Long Island are semidiurnal with a mean range of 0.88 m at the 

 Inlet entrance and an average spring tide range of 1.1 m (National Ocean Service 1993). Table 7 

 shows the water level datums for Shinnecock Inlet, relative to mllw equal to 0.00. 



Wind setup is a local phenomenon that occurs most dramatically in shallow water. During 

 strong onshore winds, setups of 0.6 to 0.9 m are not uncommon, and extremely high wind 

 velocities coupled with very low barometric pressures, i.e., tropical depressions or hurricanes, 

 have caused tides as high as 2.5 m above mlw (Hurricane Donna, 12 September 1960) in 

 Shinnecock Bay (USAE District, New York 1988). 



Currents 



In order to investigate scour holes in Shinnecock Inlet, the U.S. Army Engineer Waterways 

 Experiment Station (USAEWES) conducted current studies each year from 1991 to 1994. The 

 1991 study used an InterOcean S-4 current meter, while the 1992 to 1994 studies used a broad- 

 band acoustic doppler current profiler. The 1991 survey indicated that relatively stronger 

 currents moved along the west side of the inlet during flood tide, while stronger ebb currents 



32 Chapter 3 Physical and Coastal Processes 



