routines called by DYFIT, will be treated as subroutines. This is especially important for the 

 SETKEY/READER routine, as EXIT PROGRAM statements in the subroutine communications 

 save area in order for control to return to the calling routine. 



3. Correspondence of Identifiers 



Two types of identifiers were used as parameters in the COBOL routines to be 

 called by FORTRAN routines: FuUword real (floating point) and halfword integer (binary). 

 These variables must be aligned on fuUword boundaries, which is automatic in FORTRAN. In 

 COBOL the keyword SYNCRONIZED (abbreviated SYNC) is used to align the identifiers on a 

 fullword boundary. 



The fuUword real identifiers are declared as REAL*4 in the FORTRAN programs, 

 and defined as USAGE COMP-1 SYNC in the COBOL routines. These two definitions are fully 

 compatable. 



The halfword integer identifiers are declared as INTEGER* 2 in the FORTRAN 

 programs, and defined as PIC S9999 USAGE COMP SYNC in the COBOL routines. 



Vn. Description of Processing: DYFIT calls DYFORT which reads a parameter card specifying 

 a latitude, longitude, and time range. This card also indicates from what standard depth the data 

 is to come. SETKEY is called to position the indexed sequential file at the first record of the 

 user specified standard depth that falls within the time range chosen. The file is searched from 

 this point for dynamic depth anomaly data that falls within the specified latitude and longitude. 

 The search stops when the given time range is exceeded, the given standard depth is exceeded, 

 or the physical end of file is reached. SPLCW is then called to fit a two dimensional cubic spline 

 to the dynamic depth anomaly data. A description of SPLCW can be found in the chapter on 

 SPLPAK in volume 1 of the NCAR SOFTWARE SUPPORT LIBRARY, NCAR technical note 

 IA-105, March, 1975. Finally, DYFORT evaluates the first derivatives of the spline fit at user 

 specified locations by calling the function SPLDE. A description of SPLDE can also be found in 

 the above reference. The components of the geostrophic velocities can then be determined from 

 the formulae: 



10 ddD 



U0 = 



fRsin9 



30 





10 



adp 



V0 - 



fR 



dd 



where 



\]q - North - South component of geostrophic velocity 

 V^ = East - west component of geostrophic velocity 



B2 



