get_ti_weights_geos.c

/*******************************************************************************
Description:

  Integer function get_ti_weights_geos.c
  Calculates time-interpolation weights from L1b start time and the two GEOS
  file times.
  Computed weight is for the later of two GEOS grids.  The weight of the earlier
  one is simply (1.0 - weight).
  Called from get_GEOS.c

Input arguments:
  targhr           decimal start time of input L1b data
  gdashr1          integer hour of earlier GEOS file
  gdashr2          integer hour of later GEOS file

Output arguments:
  wt               time-interpolation weight for later GEOS time

Function output:
  int return_code  successful completion is zero, otherwise non-zero

Revision History:
  10/2012 R. Frey  Original version
  06/2021 R. Frey  Modified to use GMAO GEOS files.

Calls:
  none

*******************************************************************************/

// Includes
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

/******************************************************************************/

int get_ti_weights(float targhr, int geoshr1, int geoshr2, float *wt)

{

/******************************************************************************/

//  Declarations and initializations.

    int return_code = 0;

/******************************************************************************/

//  Calculate time-interpolation weight.

    if(geoshr2 > geoshr1) *(wt) = (targhr-(float)geoshr1) / ((float)geoshr2-(float)geoshr1);
    if(geoshr2 == geoshr1) *(wt) = 0.0;
    if(geoshr2 < geoshr1) {
      geoshr2 += 24;
      *(wt) = (targhr-(float)geoshr1) / ((float)geoshr2-(float)geoshr1);
      if( *(wt) < 0.0) {
        printf("GEOS times are incorrect! T-I weight: %f %d %d %f\n", targhr, geoshr1, geoshr2, *(wt));
        return_code = -1;
      }
    }

/******************************************************************************/

    return (return_code);

/******************************************************************************/

}