sections so that there was consistency among the various fields was maintained as 

 rigidly as possible iMontgomery 1954J . The station plots of each variable were 

 drawn against temperature and their final shapes were determined by comparing them 

 with the curves of the adjoining stations in the sections (Stroup 1954). In con- 

 structing the profiles the isopleth intervals were read from these plots, but their 

 final shape was determined by placing the profiles over the sigma-t surfaces and 

 then, with careful consideration of observed values, fairing them in as nearly 

 parallel to the sigma-t isopleths as practicable. In this report, however, all 

 surrounding stations were considered in constructing each of the station curves, 

 so greater consideration was given to the interpolated isopleth intervals. 



The values used in constructing the horizontal and lateral plots of 

 dynamic topography, temperature, salinity, and sigma-t were interpolated from the 

 individual station plots. Whenever it was possible, the spacing of the isolines 

 on these plots was determined from the cross sections. 



The topography of the sigma-t surfaces was drawn on the assumption that 

 the major components of the subsurface flow are isentropic lalong surfaces of equal 

 potential densityj. The topography of four surfaces is shown for each cruise. The 

 lowest valued surface varied from cruise to cruise and in each case was selected to 

 depict the conditions at the lower limit of the quasi-homogeneous surface layer. 

 The 24.0, 25.0, and 26.0 surfaces were selected as standard intervals to show the 

 changes in topography and conditions between the surface and the intermediate water. 

 When the variance of the salinity on these surfaces was great enough to be of value 

 in tracing the circulation, the salinity contours were superimposed. 



Instead of using the dynamic height-^ cross sections to compute veloci- 

 ties normal to the sections, as was done along the meridional sections described 

 in the previous reports, dynamic height cross sections were used to construct plots 

 of the geopotential topographyit/ for the 0- , 50-, 100- , 200- , and 300-declbar sur- 

 faces. The spacing of the contours indicates the velocity relative to the 1,000- 

 decibar surface. 



Only a single geostrophic velocity scale is shown for each of the hori- 

 zontal plots of geopotential topography. The velocities were computed for 20 N. 

 latitude using the tables and formula given in tl. 0. bl4 iLai'ond 1951J. This, 

 taking into consideration the latitudinal difference, results in an apparent error 

 of + 12 percent at the northern limits of the area (23 n.j and of -10 percent at the 

 southern limit (18°N.). Considered alone, these appear to be errors of significant 

 magnitude, however, if the indeterminable errors in direction and magnitude that 

 could be caused by internal waves and topographical complications are also consid- 

 ered, the mean velocity diagrams become more acceptable. Seiwell (1937) found that 

 internal waves would cause fluctuations in dynamic height of I4 cm. per day. Defant 

 (I95OJ found that apparent eddies appeared in the data for the coastal waters of 

 California if allowances were not made for internal waves, in the waters treated 

 in this study the proximity to land and the bottom topography would also cause de- 

 viation of the actual currents from those indicated by the dynamic topography {Parr 

 1936J. 



In order to provide a general picture of the expected incident winds and 

 currents for the cruise periods, monthly summaries of ships' reports of observed 

 winds and currents have been prepared for the area east of (upstresun from) the 



U The dynamic height is used in oceanography to express the vertical dis- 

 tance in gravitational potential between points in a selected isoDaric (pressure) 

 surface and a reference surface where the pressure field and the gravitational 

 field are assumed to coincide. It is usually expressed in dynamic meters, which 

 represents the work performed when a unit mass is lifted approximately 1 m. (.98 m. 

 at sea level) against the force of gravity. 



y The geopotential (dynamic) topography of the isobaric surfaces is simply 

 a plot of the contours of equal dynamic height. The contours represent the lines 

 along which a body can be moved without work being performed against the force of 

 gravity. 



