NASA Ocean Color

ocssw V2022

 #include "l12_proto.h"
  
 /* -----------------------------------------------------------------
  * whitecaps() - whitecap radiances per band in mW/cm^2/um/sr
  *
  * Inputs:
  * mu0[]     - Cosine of solar zenith angle
  * mu[]      - Cosine of sensor zenith angle
  * Fo[]      - Solar irradiance (mW/cm^2/um/Sr)
  * tau_r[]   - Rayleigh optical thickness per band
  * press     - Atmospheric pressure (millibars)
  * ws        - Wind speed (m/s)
  * ws_max    - Maximum allowed wind speed (m/s)
  *
  * Ouputs:
  * tLf[]     - Whitecap radiance at sensor (mW/cm^2/um/Sr)
  *
  * History:
  *
  * B. A. Franz, SAIC, Ocean Discipline Processing Group, Feb. 1999
  * 
  * - Reduced whitecap reflectance by 75%, as suggested by Gordon
  *   and implemented by the SeaWiFS project. BAF, 26 June 1998.
  *
  * - Added Frouin wavelength dependence. BAF, 13 May 1999.
  *
  * - Raised albedo multiplier from 0.25 to 0.4 and updated to new
  *   Frouin wavelength dependence, BAF, 24 May 1999
  *
  * - Converted to C.  Externalized albedos, BAF, 5 Aug 2004.
  *
  * - remove ozone transmittance, BAF, Aug 2006.
  * 
  * - replace with Stramska model for eval, SWB, Nov 2008.
  *  ----------------------------------------------------------------- */
  
 void whitecap_spectral_shape(int32_t nwave, float *wave, float *awc) {
     int nwc_tab = 8;
     float awc_wav[] = {412, 443, 490, 510, 555, 670, 765, 865};
     float awc_tab[] = {1.0, 1.0, 1.0, 1.0, 1.0, 0.889225, 0.760046, 0.644950};
     int iw;
  
     for (iw = 0; iw < nwave; iw++) {
         if (wave[iw] < 1000)
             awc[iw] = linterp(awc_wav, awc_tab, nwc_tab, wave[iw]);
         else
             awc[iw] = 0.0;
     }
 }
  
 void whitecaps(int32_t sensorID, int32_t evalmask, int32_t nwave,
         float ws, float ws_max, float rhof[]) {
     static int firstCall = 1;
     static float *awhite;
  
     float rhowc; /* White cap reflectance   */
     int32_t iw;
  
     // get spectral shape of whitecap reflectance, interpolated to
     // sensor spectral bands
  
     if (firstCall) {
         float *wave;
         firstCall = 0;
         rdsensorinfo(sensorID, evalmask, "fwave", (void **) &wave);
         if ((awhite = (float *) calloc(nwave, sizeof (float))) == NULL) {
             printf("Unable to allocate space for awhite.\n");
             exit(1);
         }
         whitecap_spectral_shape(nwave, wave, awhite);
     }
  
     // Stramska and Petelski (2003) wc fractional coverage for underdeveloped seas
     float ws_min = 6.33;
     if (ws > ws_min && ws_max > ws_min) {
         rhowc = 1.925E-5 * pow((MIN(ws, ws_max) - ws_min), 3.00);
         for (iw = 0; iw < nwave; iw++)
             rhof[iw] = awhite[iw] * rhowc;
     } else {
         for (iw = 0; iw < nwave; iw++)
             rhof[iw] = 0.0;
     }
  
 }
  
  