flexdoxygen/20151015/interpol__rain_8f90_source.html

 !**********************************************************************

 ! Copyright 1998,1999,2000,2001,2002,2005,2007,2008,2009,2010         *

 ! Andreas Stohl, Petra Seibert, A. Frank, Gerhard Wotawa,             *

 ! Caroline Forster, Sabine Eckhardt, John Burkhart, Harald Sodemann   *

 !                                                                     *

 ! This file is part of FLEXPART.                                      *

 !                                                                     *

 ! FLEXPART is free software: you can redistribute it and/or modify    *

 ! it under the terms of the GNU General Public License as published by*

 ! the Free Software Foundation, either version 3 of the License, or   *

 ! (at your option) any later version.                                 *

 !                                                                     *

 ! FLEXPART is distributed in the hope that it will be useful,         *

 ! but WITHOUT ANY WARRANTY; without even the implied warranty of      *

 ! MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the       *

 ! GNU General Public License for more details.                        *

 !                                                                     *

 ! You should have received a copy of the GNU General Public License   *

 ! along with FLEXPART.  If not, see <http://www.gnu.org/licenses/>.   *

 !**********************************************************************


 subroutine interpol_rain(yy1,yy2,yy3,nxmax,nymax,nzmax,nx, &

        ny,memind,xt,yt,level,itime1,itime2,itime,yint1,yint2,yint3)

   !                          i   i   i    i    i     i   i

   !i    i    i  i    i     i      i      i     o     o     o

   !****************************************************************************

   !                                                                           *

   !  Interpolation of meteorological fields on 2-d model layers.              *

   !  In horizontal direction bilinear interpolation interpolation is used.    *

   !  Temporally a linear interpolation is used.                               *

   !  Three fields are interpolated at the same time.                          *

   !                                                                           *

   !  This is a special version of levlininterpol to save CPU time.            *

   !                                                                           *

   !  1 first time                                                             *

   !  2 second time                                                            *

   !                                                                           *

   !                                                                           *

   !     Author: A. Stohl                                                      *

   !                                                                           *

   !     30 August 1996                                                        *

   !                                                                           *

   !****************************************************************************

   !                                                                           *

   ! Variables:                                                                *

   !                                                                           *

   ! dt1,dt2              time differences between fields and current position *

   ! dz1,dz2              z distance between levels and current position       *

   ! height(nzmax)        heights of the model levels                          *

   ! indexh               help variable                                        *

   ! indz                 the level closest to the current trajectory position *

   ! indzh                help variable                                        *

   ! itime                current time                                         *

   ! itime1               time of the first wind field                         *

   ! itime2               time of the second wind field                        *

   ! ix,jy                x,y coordinates of lower left subgrid point          *

   ! level                level at which interpolation shall be done           *

   ! memind(3)            points to the places of the wind fields              *

   ! nx,ny                actual field dimensions in x,y and z direction       *

   ! nxmax,nymax,nzmax    maximum field dimensions in x,y and z direction      *

   ! xt                   current x coordinate                                 *

   ! yint                 the final interpolated value                         *

   ! yt                   current y coordinate                                 *

   ! yy(0:nxmax,0:nymax,nzmax,3) meteorological field used for interpolation   *

   ! zt                   current z coordinate                                 *

   !                                                                           *

   !****************************************************************************


   implicit none


   integer :: nx,ny,nxmax,nymax,nzmax,memind(2),m,ix,jy,ixp,jyp

   integer :: itime,itime1,itime2,level,indexh

   real :: yy1(0:nxmax-1,0:nymax-1,nzmax,2)

   real :: yy2(0:nxmax-1,0:nymax-1,nzmax,2)

   real :: yy3(0:nxmax-1,0:nymax-1,nzmax,2)

   real :: ddx,ddy,rddx,rddy,dt1,dt2,dt,y1(2),y2(2),y3(2)

   real :: xt,yt,yint1,yint2,yint3,p1,p2,p3,p4


   ! If point at border of grid -> small displacement into grid

   !***********************************************************


   if (xt.ge.real(nx-1)) xt=real(nx-1)-0.00001

   if (yt.ge.real(ny-1)) yt=real(ny-1)-0.00001


   !**********************************************************************

   ! 1.) Bilinear horizontal interpolation

   ! This has to be done separately for 2 fields (Temporal)

   !*******************************************************


   ! Determine the lower left corner and its distance to the current position

   !*************************************************************************


   ix=int(xt)

   jy=int(yt)

   ixp=ix+1

   jyp=jy+1

   ddx=xt-real(ix)

   ddy=yt-real(jy)

   rddx=1.-ddx

   rddy=1.-ddy

   p1=rddx*rddy

   p2=ddx*rddy

   p3=rddx*ddy

   p4=ddx*ddy


   ! Loop over 2 time steps

   !***********************


   do m=1,2

     indexh=memind(m)


     y1(m)=p1*yy1(ix ,jy ,level,indexh) &

          + p2*yy1(ixp,jy ,level,indexh) &

          + p3*yy1(ix ,jyp,level,indexh) &

          + p4*yy1(ixp,jyp,level,indexh)

     y2(m)=p1*yy2(ix ,jy ,level,indexh) &

          + p2*yy2(ixp,jy ,level,indexh) &

          + p3*yy2(ix ,jyp,level,indexh) &

          + p4*yy2(ixp,jyp,level,indexh)

     y3(m)=p1*yy3(ix ,jy ,level,indexh) &

          + p2*yy3(ixp,jy ,level,indexh) &

          + p3*yy3(ix ,jyp,level,indexh) &

          + p4*yy3(ixp,jyp,level,indexh)

   end do


   !************************************

   ! 2.) Temporal interpolation (linear)

   !************************************


   dt1=real(itime-itime1)

   dt2=real(itime2-itime)

   dt=dt1+dt2


   yint1=(y1(1)*dt2+y1(2)*dt1)/dt

   yint2=(y2(1)*dt2+y2(2)*dt1)/dt

   yint3=(y3(1)*dt2+y3(2)*dt1)/dt


 end subroutine interpol_rain

interpol_rain
subroutine interpol_rain(yy1, yy2, yy3, nxmax, nymax, nzmax, nx, ny, memind, xt, yt, level, itime1, itime2, itime, yint1, yint2, yint3)
Definition: interpol_rain.f90:22