WIND SPEED, M/SEC 



Figure 9. — Evaporation diagram for the 1956-70 mean values of the 

 vapor pressure difference, se = e^ ■ ^a' *"<' wind speed, W, with 

 monthly values for the fall and winter of 1956-57 and 1967-68. ie is in 

 mb and W in m sec"' . Months are indicated by Roman numerals. The 

 curvilinear isopleths give the evaporation rate in contour intervals of 

 100 cal cm'^ day' . 



An anomalously high evaporation rate was experienced 

 at OWS-V during the fall of 1956 and winter of 1957. For 

 these months values of Ae and W are plotted in Figure 9. It 

 is evident that although the wind speed for December 1956 

 and January 1957 were more than 1 m sec"' higher than 

 normal, the principal contribution to the anomalously high 

 evaporation was an anomalously high Ae. Other anomalous- 

 ly high evaporation months were November 1967 and 

 February 1968. During November 1967 the wind speed was 

 near normal, but Ae was 4.1 mb above normal (Fig. 9). 

 During February 1968, although Ae was above normal, the 

 most significant factor in the high evaporation was the 

 anomalously high (3.5 m sec"' above normal) wind speed. 



These examples reveal that either Ae or W can be the 

 principal cause for an anomalous evaporation rate at 

 OWS-V. However, a comparison of the seasonal anomalies 

 of wind speed at OWS-V (Fig. 10) with the seasonal 

 anomalies of the evaporative heat loss (Fig. 8) indicates 

 that anomalous evaporation rates are usually associated 

 with anomalous wind speeds. 



Effect of Stability on Q(E) 



Although it is premature to apply refinements that are 

 still under investigation in the routine computations of 

 air-sea interaction processes, it is interesting to determine 

 the probable effects of atmospheric stability on the 

 computation of Q(E). Deardorff (1968) defined the bulk 

 Richardson number as a practical, dimensionless measure 

 of atmospheric stability. He derived empirical expressions 

 as functions of the bulk Richardson number to correct the 



Figure 10. -Seasonal anomalies of wind speed at Ocean Weather Station V (OWS-V), October 1951-March 

 1971, for 6-mo cooling (solid bar) and 6-mo warming (dashed bar) portions of the annual cycle. Anomalies 

 are relative to the 1952-70 mean values. Values prior to April 1955 were adjusted for the change in latitude 

 of OWS-V. 



15 



