THE PROGRAM 



To put this method into use a spline fit program called SPLPAK which employs third order 

 polynomials was obtained form the National Center for Atmospheric Research (NCAR) Software 

 Support Library. The SPLPAK program has several options, the most important of which is 

 the number of rectangles into which the area to be fitted is to be divided. Since it was assumed 

 that, even with sphne fits, the area to be analyzed would be too large to be fitted by a single 

 spline fit, it M^as specified for the program to have simply nine rectangles, as shown in Figure 1, 

 with the size of the rectangles being left as a variable to be determined by the needs of the parti- 

 cular area under study. The idea behind using nine rectangles was that the best fit to the data 

 should occur in the center rectangle where tlie effects of the outer boundary are least significant. 

 The total area of interest would then be analyzed by chosing an appropriate size for the nine 

 rectangles according to the amount of structure present and then moving the center rectangle 

 around the total area of interest witli some continuity being suppUed from one position of the 

 center rectangle to an adjacent position by means of the overlapping effect of the eight sur- 

 rounding rectangles. This approach would allow different size areas to be analyzed with equal 

 accuracy and also allow for the development of a generalized program apphcable to any area. 

 A fuller explanation of SPLPAK and its otlier options can be found in Adams et al. (1975). 



In order to utilize SPLPAK a program called XTRACT was written to read a standard NODC 

 data tape and write on disk the appropriate input data required by SPLPAK. A program called 

 DYFIT was then written which would read the data from the desk, caU SPLPAK as a subroutine 

 and evaluate the components of the geostrophic velocity at any specified location. Besides the 

 size of the rectangles, the relative depth to which the currents are to be referenced and the time 

 period over which the currents are to be averaged are variables which must be specified in DYFIT. 



