NOAA PROFESSIONAL PAPER 11 



14 



12 



10 



8 



in C: 

 LL) O 



o 



FEBRUARY 



cr 

 oc 



O 2 



O 



O 



en 



UJ 



3 

 Z 14 



h-^ "g 



1-30 ' 31-60 ' 61^90 91-120 I 121-150 ' 151-180 181-210 211-240 241-270 271-300 I 301-330 ' 331-360 



MARCH 



12 



10 



8 



6 

 4 

 2 

 



LU LU g 



w in 



1-30 I 31-60 I 61-90 I 91-120 | 121-150| 151-180 I 181-210 I 211-240 I 241- 



COMPASS SECTOR 



FIGURE 3-8. — Resultant mean wind directions over New York Bight marine areas by 30° compass sectors, February-June, 1949-76 



(arrows indicate prevailing directions in 1976). 



mean wind-flow patterns for the seven months. During 

 February and March, the ciimatological resultant flow is 

 from the northwest because the area is normally influ- 

 enced by repeated polar outbreaks. April is a transition 

 month between the northerly regime of winter and the 

 southerly regime of summer, with winds weakly predom- 

 inant from the west. Prevailing winds from May through 

 August are from the south and southwest, but in May the 

 wind constancy is considerably less than in June, as the 

 region is influenced by a greater number of disturbances 

 from the west. The constancy is defined as the ratio, 



|V«|/t7 



where V^ is the mean vector wind and U is the scalar 

 mean wind speed. In contrast to climatology, the winds 

 for February and March 1976 have a net southerly com- 

 ponent south of about 40.5° N, and February exhibits un- 

 usually large constancy values. The flow patterns for the 



other months are closer to the mean, but May and June 

 exhibit substantially higher directional persistence. It 

 should be noted that the surface winds during June agree 

 well with conditions necessary to wash floatable material 

 along the Long Island south shore beaches (Swanson et 

 al. 1978). 



To further quantify the uniqueness of the wind patterns 

 during 1976, the frequency distribution of resultant monthly 

 wind vectors by 30° sectors for each of the four marine 

 areas was tabulated. The results (fig. 3-8) show the num- 

 ber of years, beginning in 1949, that the prevailing winds 

 for each month, February through June, "blew" from a 

 given direction. 



Thus, during February (including 1976) resultant wind 

 direction from 24r-270° occurred about six times or 

 nearly 21 percent of the time in the northern two areas 

 and in the southern two areas from 2ir-240° two times, 

 or less than 10 percent of the time. During March, re- 



66 



