salinity ; water masses, and their characteristics; 

 and the variation of temperature and salinity 

 with depth. To plot temperature-salinity rela- 

 tionships, the U.S. Naval Oceanographic Office 

 uses the Temperature-Salinity Plottnig Sheet, 

 NHO-3167/59 (fig. S-3). This graph indicates 

 density values for the range of temperature and 

 salinity it covers. 



Using the data for observed temperature and 

 salinity values, plot each point and draw a 

 smooth curve through the plotted points. Wlien 

 interpolated values at standard depths have 

 been determined (see par. S-5), indicate the 

 points on the T-S curve, and enter the standard 

 depth to the right of the curve. 



S-5 Obtaining Interpolated Values.— 



Oceanographic data values of temj^erature. 



salinity, dissolved oxygen, sound velocity, and 

 density (cr,) for standard depths (par. D-10) 

 may be interpolated from plotted observed value 

 curves, or they may be obtained by electronic 

 computer data analysis. 



To find an interpolated value on the Oceano- 

 graphic Station plotting sheet, simply locate the 

 intersection of the curve and the horizontal line 

 which represents the desired standard depth, 

 and read the corresponding value at the top of 

 the graph. Enter interpolated values on the 

 E-Sheet. 



To obtain interpolated values by electronic 

 computer data analysis, CODE THE DATA 

 on the Physical and Chemical Data Form for 

 Oceanographic Stations, NODC-EXP-3167/25 

 (3-64), (fig. S-t), and forward to the National 



Figure S-4. Physical and Chemical Data Form for Oceanographic stations. 



S-5 



223-812 O - 68 - L3 



