hydrosnow.c

/*-------------------------------------------------------------------------------------------
 *  HydroSnow.c
 *
 *	Author: Albert Kettner, March 2006
 *
 *  Calculates the daily snow fall or melt for each altitude bin.
 *  Also calculates the groundwater flow and time lag due to the snow.
 *
 * Variable		Def.Location	Type	Units	Usage
 * --------		------------	----	-----	-----
 * err			various			int		-		error flag halts program
 * ii			various			int		-		temporary loop counter
 * jj			various			int		-		temporary loop counter
 * kk			various			int		-		temporary loop counter
 * shldday[]	HydroSnow.c		double	m^3/s	shoulder discharge array
 * Tcorrection	HydroSnow.c		double	degC	melt modifier for rain fall
 * melt			HydroSnow.c		double	m		snow melt on a given day
 * Minput		HydroSnow.c		double	m^3/a	snow input in a year
 * Mout			HydroSnow.c		double	m^3/a	snow melt output in a year
 * Mwrapin		HydroSnow.c		double	m^3/a	nival discharge from previous year
 * Mwrapout		HydroSnow.c		double	m^3/a	nival discharge to next year
 * Mgw			HydroSnow.c		double	m^3/a	total nival discharge put into GW
 * Mnival		HydroSnow.c		double	m^3/a	total nival discharge
 *
 *
 *  The ELA index for each year (ELAindex) was found in HydroGlacial.c
 *  The FLA index for each day (FLAindex[]) was found in HydroHypsom.c
 *  The FLAflag (=9999) indicates the snow line was above the maximum
 *  altitude of the basin on that day
 *
 *-------------------------------------------------------------------------------------------*/

#include "hydroclimate.h"
#include "hydroparams.h"
#include "hydrotimeser.h"
#include "hydroinout.h"
#include "hydrodaysmonths.h"

/*----------------------
 *  Start of HydroSnow
 *----------------------*/
int
hydrosnow ()
{

/*-------------------
 *  Local Variables
 *-------------------*/
  int err, ii, jj, kk;
  double shldday[maxday], Tcorrection, melt;
  double Minput, Mout, Mwrapin, Mwrapout, Mgw, Mnival;

/*-----------------
 *  Set Variables
 *-----------------*/
  err = 0;
  Minput = 0.0;
  Mgw = 0.0;
  Mnival = 0.0;
  Mout = 0.0;
  MPnival = 0.0;
  Mwrapin = 0.0;
  Mwrapout = 0.0;
  Msnowend = 0.0;
  Msnowstart = 0.0;
  Snowremains = 0.0;

/*-----------------------------------------------
 *  Make sure the shoulder day arrays are clean
 *-----------------------------------------------*/
  for (ii = 0; ii < maxday; ii++)
    shldday[ii] = 0.0;

/*----------------------------------------------------
 *  Calculate the carryover snow for mass balance.
 *  Storing the carryover of snow from previous year
 *  is done in HydroHypsom.c
 *----------------------------------------------------*/
  for (kk = 0; kk < nelevbins; kk++)
    Msnowstart += Snowelevday[kk][0] * areabins[kk];

/*-----------------------------------------------------------
 *  Loop through the days adding snowfall
 *  Loop through the Temperature Elevation bins looking for
 *  potential snowfall.
 *  "Snow" only occurs above the FLA and below the ELA
 *  everything above the ELA is considered "Ice"
 *  Snow is stored in "m" of water equivalent
 *-----------------------------------------------------------*/
  for (ii = 0; ii < daysiy; ii++)
    for (kk = FLAindex[ii]; kk < nelevbins && kk < ELAindex; kk++)
      if (Pdaily[ii] > 0.0)
        {
          Snowelevday[kk][ii] += Pdaily[ii];
          MPnival += Pdaily[ii] * areabins[kk];
        }

/*----------------------------------------------------
 *  Loop through the days/elev bins melting snowfall
 *----------------------------------------------------*/
  for (ii = 0; ii < daysiy; ii++)
    {
      for (kk = 0; kk < ELAindex && kk < nelevbins; kk++)
        {

      /*--------------------------------------------------------
       *  Melt snow if T is warm enough (and if there is snow)
       *--------------------------------------------------------*/
          if (Televday[kk][ii] > 1.0 && Snowelevday[kk][ii] > 0.0)
            {

         /*---------------------------------------------------
          *  Snow melt = 1cm/degC  ( -1cm if it is raining )
	  *  Meltrate  = x m/degC
	  *  Snow melt = Meltrate * T = m/degC * degC = m
          *---------------------------------------------------*/
              Tcorrection = 0.0;
              if (Pdaily[ii] > 0.0)
                Tcorrection = 1.0;
              melt =
                mn (Meltrate * (Televday[kk][ii] - Tcorrection),
                    Snowelevday[kk][ii]);

         /*---------------------------------------------------------------------
	  *  (Mark's version of routing)
	  *  Add the time lag for the distance up the basin (distbins[elabin])
	  *---------------------------------------------------------------------*/
              Qnival[ii + distbins[kk]] += melt * areabins[kk] / dTOs;
              Snowelevday[kk][ii] -= melt;
            }
        }

   /*-------------------------------------------------
    *  Check how much snow is remaining on August 31
    *-------------------------------------------------*/
      if (ii == dayendm[7])
        {
          for (kk = 0; kk < nelevbins; kk++)
            Snowremains += Snowelevday[kk][ii] * areabins[kk];

          if (setstartmeanQandQs == 4)
            if (Snowremains > 1)
              {
                fprintf (stderr,
                         "\n \t HydroSnow Warning: There is Snow remaining on August 31 \n");
                fprintf (stderr, " \t Snowremains \t = %e (m^3) \n",
                         Snowremains);
                fprintf (stderr, " \t in year: %d \n", yr);
                fprintf (fidlog,
                         "\n \t HydroSnow Warning: There is Snow remaining on August 31 \n");
                fprintf (fidlog, " \t Snowremains \t = %e (m^3) \n",
                         Snowremains);
                fprintf (fidlog, " \t in year: %d \n", yr);
              }
        }

  /*------------------------------------------
   *  Add any remaining snow to the next day
   *------------------------------------------*/
      for (kk = 0; kk < nelevbins; kk++)
        if (ii < daysiy - 1)
          {
            Snowelevday[kk][ii + 1] += Snowelevday[kk][ii];
            Snowelevday[kk][ii] = 0.0;
          }
    }                           /* end daily loop */

/*-------------------------------------------------------------------
 *  Distribute the melted snow to E, GW, and shoulders for each day
 *  account for evaporation (m/day)
 *  I have distributed the E by the area of the basin
 *  which is not technically correct, but creates the
 *  correct units
 *-------------------------------------------------------------------*/
  for (ii = 0; ii < daysiy; ii++)
    {
      Enivalannual += Qnival[ii] * dryevap[ep] * dTOs / totalarea[ep];
      Qnival[ii] -= Qnival[ii] * dryevap[ep];
    }

/*------------------------------------------------------------
 *  Create the shoulder events (Murray's version of routing)
 *  there is one left (preceeding) day scaled as:
 *  shoulderleft*event
 *  the main event is scaled down to:
 *  shouldermain*event
 *  there are 1 or more right (following days) scaled to:
 *  shoulderright[]*event
 *  1.0 = Sum(shoulderleft+shouldermain+shoulderright[])
 *------------------------------------------------------------*/
  ii = 0;
  if (Qnival[ii] > 0.0)
    {
      shldday[ii] += shoulderleft * Qnival[ii];
      for (jj = 0; jj < shouldern - 2; jj++)
        shldday[ii + jj + 1] += shoulderright[jj] * Qnival[ii];
      Qnival[ii] = shouldermain * Qnival[ii];
    }
  for (ii = 1; ii < daysiy; ii++)
    if (Qnival[ii] > 0.0)
      {
        shldday[ii - 1] += shoulderleft * Qnival[ii];
        for (jj = 0; jj < shouldern - 2; jj++)
          shldday[ii + jj + 1] += shoulderright[jj] * Qnival[ii];
        Qnival[ii] = shouldermain * Qnival[ii];
      }

/*----------------------------------------------------------------
 *  Add the shoulder events and the main events to get the total
 *----------------------------------------------------------------*/
  for (ii = 0; ii < maxday; ii++)
    Qnival[ii] += shldday[ii];

/*--------------------------------------------
 *  Add the carryover from the previous year
 *  and track it's mass
 *--------------------------------------------*/
  for (ii = 0; ii < maxday - daysiy; ii++)
    {
      Qnival[ii] += Qnivalwrap[ii];
      Mwrapin += Qnivalwrap[ii] * dTOs;
    }

/*-------------------------------------------------------------
 *  Add to the flux to the Groundwater pool
 *  The actual addition to the GW pool is done in HydroRain.c
 *-------------------------------------------------------------*/
  for (ii = 0; ii < daysiy; ii++)
    {
      Qnivaltogw[ii] = percentgw * Qnival[ii];
      Qnival[ii] -= Qnivaltogw[ii];
      Mgw += Qnivaltogw[ii] * dTOs;
    }

/*--------------------------------
 *  Check the mass balance (m^3)
 *--------------------------------*/
  for (ii = 0; ii < daysiy; ii++)
    Mnival += Qnival[ii] * dTOs;
  for (ii = daysiy; ii < maxday; ii++)
    Mwrapout += Qnival[ii] * dTOs;
  for (kk = 0; kk < nelevbins; kk++)    /* the remaining snow */
    Msnowend += Snowelevday[kk][daysiy - 1] * areabins[kk];

  Mout = Mgw + Mnival + Enivalannual * totalarea[ep] + Msnowend + Mwrapout;
  Minput = MPnival + Mwrapin + Msnowstart;

  if ((fabs (Mout - Minput) / Minput) > masscheck)
    {
      fprintf (stderr, "\nERROR in HydroSnow: \n");
      fprintf (stderr, "  Mass Balance error: Mout != Minput \n\n");

      fprintf (stderr, "\t fabs(Mout-Minput)/Minput > masscheck \n");
      fprintf (stderr, "\t note: masscheck set in HydroParams.h \n");
      fprintf (stderr, "\t masscheck     \t = %f (%%) \n", masscheck);
      fprintf (stderr, "\t abs(out-in)/in\t = %f (%%) \n",
               fabs (Mout - Minput) / Minput);
      fprintf (stderr, "\t out-in        \t = %e (m^3) \n\n", Mout - Minput);

      fprintf (stderr, " \t Minput = MPnival + Mwrapin + Msnowstart (m^3) \n");
      fprintf (stderr, " \t Minput       \t = %e \n", Minput);
      fprintf (stderr, " \t MPnival      \t = %e \n", MPnival);
      fprintf (stderr, " \t Mwrapin      \t = %e \n", Mwrapin);
      fprintf (stderr, " \t Msnowstart   \t = %e \n\n", Msnowstart);

      fprintf (stderr,
               " \t Mout = Mnival + Mgw + Enivalannual + Msnowend + Mwrapout (m^3) \n");
      fprintf (stderr, " \t Mout         \t = %e \n", Mout);
      fprintf (stderr, " \t Mnival       \t = %e \n", Mnival);
      fprintf (stderr, " \t Mgw          \t = %e \n", Mgw);
      fprintf (stderr, " \t Enivalannual \t = %e \n",
               Enivalannual * totalarea[ep]);
      fprintf (stderr, " \t Mwrapout     \t = %e \n", Mwrapout);
      fprintf (stderr, " \t Msnowend     \t = %e \n\n", Msnowend);
      exit (-1);
    }

  return (err);
}                               /* end of HydroSnow.c */