SECT. 2] LARGE-SCALE INTERACTIONS 187 



typical of the North Atlantic (position of Weather Ship C, latitude 52° 45'N, 

 longitude 35^^ 30'W). 



For the tropical situation, tlie wind data from the research vessel of the 

 Woods Hole Oceanographic Institution's April, 1946, Wy man- Woodcock 

 expedition (see Table II) were used. In this case the winds were measured every 

 few hours in knots using carefully mounted anemometers. The resultant stress 

 for this seventeen-day period was determined from (17) in the following ways : 

 (i) directly from calculating each rectangular component for each observation, 

 using the cd of the solid line of Fig. 6, and (ii) by means of constructing a wind 

 rose for the period (Fig. 44). Resultant stress was computed from the wind rose 

 in three different ways : first, using the Scripps method for the Atlantic (mean 

 speed for Beaufort intervals, some lumped) ; secondly, using the Scripps 

 method for the Pacific (normal distribution within each Beaufort interval) ; 

 and, thirdly, using a revised version of the Scripps Atlantic method (mean 

 speed in each Beaufort interval) with the Cd of the solid line of Fig. 6, instead 

 of the dashed line used in all the Scripps calculations. The results are shown in 

 Table XIV. 



Table XIV 



Ocean Surface Stress Determinations from Research-Vessel Tropical-Wind 



Data, Wyman Expedition 



19° 30'N', 66°W 



April 1-4, 12-17, 22-28, 1946 



p = 1.16 X 10-3 gcm-3 



Surface stress 



Method Direction, Magnitude, 



° from N dynes/cm^ 



I. Direct summation 



Solid curve Fig. 6 069 0.625 



II. Wind rose 



Scripps Pacific 



Scripps Atlantic 



Mod. Scripps Atlantic 

 (cj) solid curve, Fig. 6) 

 TO = p^D~<a^ Mean wind speed for period 

 TO = pcjyua^ Resultant wind for period 

 Resultant wind for period : 068°, 5.4 m/sec 

 Average wind speed for period : 6.6 m/sec 

 Directional wind steadiness for period: 82% 



The most important conclusion to be drawn from this table is the close 

 agreement of the results of all methods of computation, with the extreme 



