their corresponding serial numbers, lino for 

 line. 



14-136 Salinity %o.— The salinity of the 

 water, in parts per thousand, is obtained from 

 the column of the same heading on the D-sheet. 

 Be sure that they agree with their correspond- 

 ing serial numbers, line for line. 



14-137 at. — This value is called sigma t 

 (at). It represents, in abbreviated form, the 

 density of the water samples at atmospheric 

 pressure as determined by the temperature 

 and salinity of each sample. It maj- be deter- 

 mined in several ways: from table 17, or from 

 the tables in H. O. Pub. No. 614, Processing 

 Oceanographic Data, or in H. O. Pub. No. 615, 

 Tables for Sea Water Density. Another 

 method is by use of nomographs such as H. O. 

 Misc. 15530-1 through 15530-6, Nomographs 

 for Determination of Density from Salinity and 

 Temperature of Sea Water. This set of 6 

 nomographs covers salinity ranges from °/oo to 

 42 °/oo- A sample is shown in figure 14-7. 



14-138 Determining at. — The at is deter- 

 mined from the nomograph by laying a straight- 

 edge across the given temperature (21.33° C.) 

 on the right and the given salinity (35.79°/oo) 

 on the left, and reading the desired density 

 (25.03) from the at column that is marked with 

 the same symbol (a square in this example) 

 as the temperature column used. Density 

 (at) is always recorded on the log sheet to two 

 decimal places. 



14-139 O2 ml/l.~The amount of dissolved 

 oxygen, in milliliters per liter, is obtained from 

 the column of the same heading in the C-sheet. 

 Be sure that the values agree with their corre- 

 sponding serial numbers, line for line. 



14-140 Blank Columns.— Two blank col- 

 umns are provided for recording any other 

 observed values that may be determined from 

 the sea water samples. These may include 

 pH, phosphates, silicates, nitrates, etc. Indi- 

 cate in the column head the type of determi- 

 nation recorded and the units used. Example: 

 SiOa, mg-A/L. 



14-141 PLOTTING OBSERVED VALUES 

 ON GRAPHS.—After the Observed Values 

 have been recorded on the log sheet, they are 

 plotted against depth in meters on graph paper. 

 H. O. Misc. 12,252-A, Oceanographic Station 

 Plotting Sheet, provides for plotting tempera- 

 tures, salinities, densities, and dissolved oxygen 

 values against the accepted depths. In the 

 event the ranges of the station's Observed 

 Values exceed those given on this sheet, any 

 good graph paper, of the scale of 10 x 10 to 

 the }i inch, may be used. Detailed instruc- 

 tions for plotting graphs are given in chapter 4. 



H. O. 607 



350676 O—&6 11 



14-142 Std. Depth,— By international 

 agreement, certain specified depths, in meters 

 below the surface, were selected and desig- 

 nated as Standard Depths. All physical oceano- 

 graphic values are adjusted to these standard 

 depths. The standard depths are: surface, 10, 

 20, 30, 50, 75, 100, 150, 200 (250), 300, 400, 500, 

 600, (700), 800, 1,000, 1,200, 1,500, 2,000, 

 2,500, 3,000, 4,000, and thereafter every 1,000 

 meters to the bottom. The depths in paren- 

 theses are optional. 



14-143 T°C. — From the graph constructed 

 with the Observed Values, read the temperature 

 for each standard depth and record the value in 

 this column. 



14-144 Salinity °/oo- — From the graph con- 

 structed with the Observed Values, read the 

 salinity for each standard depth and record 

 the value in this column. 



14-145 at. — From the graph constructed 

 with the Observed Values, read the at for each 

 standard depth and record the value in this 

 column. As each density is determined, check 

 the value by taking the standard depth tem- 

 perature and salinity and obtain the density 

 by table or nomograph as was done for the 

 Observed Values for density. This value 

 should agree with the density as determined 

 by the plotted graph. Thus, if any Observed 

 Value is incorrectly plotted, or standard depth 

 value misread, the error may be caught. 



14-146 DYNAMIC CALCULATIONS COL- 

 UMNS. — The dynamic calculations columns 

 are used for the determination of dynamic 

 height anomalies. The dynamic height anom- 

 alies are used for computing oceanic currents. 



14-147 5. — This column is used for record- 

 ing the value of the Specific Volume Anomaly. 

 The Specific Volume Anomaly is determined, 

 for this log sheet, by means of nomographs. 

 Another method, using tables, is given in H. O. 

 Pub. No. 614, "Processing Oceanographic 

 Data." The nomographs used with this log 

 sheet are: H. O. Misc. 15,078— A & B. Pres- 

 sure Correction to Specific Volume Anomaly, 

 and H. O. Misc. 15,078-1 through 12, Specific 

 Volume Anomalv Diagrams. 



14-148 HOW TO USE THE SPECIFIC 

 VOLUME ANOMALY DIAGRAMS.— To find 

 the Specific Volume Anomaly (8) the depth, 

 temperature, and salinity must be known. In 

 these instructions, the following values are used 

 for the example: 



Depth : 2,000 meters. 

 T°C.: 3.50. 

 S°/„o: 34.94. 

 Find: 5. 



149 



