alert_rain.c

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/*  possible error returns
 
    -1 no report after begin time
    -2 no report after end time
    -3 time gap between begin time and first report after begin time too large
    -4 data not reliable
    -5 large gaps in data
 
    r->rn    amount of rain
    r->tdif    time gap of end time and last report
    
                                                                 */
 
#include "prototypes.h"
 
alert_rain(struct stn_values *stn_values,int inum,
           time_t tstart,time_t tstop,struct rainfall *r)
 
{
 
int j,eflag;
float fdif;
long tdif;
 
r->rn=0.0;
r->rel=0;
r->obs=0;
r->tskips=0;
r->tdif=0L;
fdif=0.0;
 
eflag=-1;
 
for(j=0;j<inum;j++) {
 
         /* observation time before start time */
 
                if(stn_values[j].clock > tstart)
                                      continue;
 
                if(r->obs==0 && (tstart - stn_values[j].clock) > r->maxtdif && fdif >r->maxgap) {         
 
                                                  r->tdif=tstart-stn_values[j].clock;
                                                  return(-3);
 
                                                                           }
 
                if(j==0 && (tstart - stn_values[j].clock) > r->maxtdif) {         
 
                                                  r->tdif=tstart-stn_values[j].clock;
                                                  return(-3);
 
                                                                           }
 
                 if(j > 0) {
 
                          tdif=stn_values[j-1].clock -  stn_values[j].clock;
                          fdif=stn_values[j-1].value  -  stn_values[j].value;
                   
                          /* correction for cycles of 100 */
 
                          if ( r->cycle==100 && fdif >= -4.00 && fdif < -2.00) 
                                      fdif=fdif+ 4.00;
 
                            }
 
                if(stn_values[j].clock < tstop) {
 
                                   if(r->obs < 1 || fdif <= 0) 
                                             return(1);
 
                                   /*gross error check*/
 
                                   if(fdif > r->maxgap*2)
                                             return(-5);
 
                                   /* more than 10 days gap */
 
                                   if((tstop-stn_values[j].clock) > r->maxtdif)
                                             return(-5);     
 
                                   r->rn=r->rn + fdif;
 
                                   if(fdif<=r->maxgap/5)    
                                             return(1);
 
                                   else
                                             return(-5);
 
                                         }
 
                r->obs++;
                eflag=-2;
 
                if(r->obs <= 1)
                            continue;
 
                if(tdif > r->maxtdif && fdif != 0) 
                                         r->tskips++;
 
 
 
                if(fdif < 0 || fdif >= r->maxgap) {
 
                                         r->rel++;
                                         if(r->rel >= 2)
                                                    eflag=-4;
 
                                              }
 
               else 
                    r->rn=r->rn+fdif;
 
         /* observation time after end time */
 
            }
 
return(eflag);
 
}