1 | ! SPDX-FileCopyrightText: FLEXPART 1998-2019, see flexpart_license.txt |
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2 | ! SPDX-License-Identifier: GPL-3.0-or-later |
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3 | |
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4 | subroutine interpol_rain(yy1,yy2,yy3,nxmax,nymax,nzmax,nx, & |
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5 | ny,iwftouse,xt,yt,level,itime1,itime2,itime,yint1,yint2,yint3) |
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6 | ! i i i i i i i |
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7 | !i i i i i i i i o o o |
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8 | !**************************************************************************** |
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9 | ! * |
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10 | ! Interpolation of meteorological fields on 2-d model layers. * |
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11 | ! In horizontal direction bilinear interpolation interpolation is used. * |
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12 | ! Temporally a linear interpolation is used. * |
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13 | ! Three fields are interpolated at the same time. * |
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14 | ! * |
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15 | ! This is a special version of levlininterpol to save CPU time. * |
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16 | ! * |
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17 | ! 1 first time * |
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18 | ! 2 second time * |
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19 | ! * |
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20 | ! * |
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21 | ! Author: A. Stohl * |
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22 | ! * |
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23 | ! 30 August 1996 * |
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24 | ! * |
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25 | !**************************************************************************** |
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26 | ! * |
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27 | ! Variables: * |
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28 | ! * |
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29 | ! dt1,dt2 time differences between fields and current position * |
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30 | ! dz1,dz2 z distance between levels and current position * |
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31 | ! height(nzmax) heights of the model levels * |
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32 | ! indexh help variable * |
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33 | ! indz the level closest to the current trajectory position * |
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34 | ! indzh help variable * |
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35 | ! itime current time * |
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36 | ! itime1 time of the first wind field * |
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37 | ! itime2 time of the second wind field * |
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38 | ! ix,jy x,y coordinates of lower left subgrid point * |
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39 | ! level level at which interpolation shall be done * |
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40 | ! iwftouse points to the place of the wind field * |
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41 | ! nx,ny actual field dimensions in x,y and z direction * |
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42 | ! nxmax,nymax,nzmax maximum field dimensions in x,y and z direction * |
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43 | ! xt current x coordinate * |
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44 | ! yint the final interpolated value * |
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45 | ! yt current y coordinate * |
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46 | ! yy(0:nxmax,0:nymax,nzmax,3) meteorological field used for interpolation * |
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47 | ! zt current z coordinate * |
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48 | ! * |
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49 | !**************************************************************************** |
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50 | use par_mod, only: numwfmem |
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51 | |
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52 | implicit none |
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53 | |
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54 | integer :: nx,ny,nxmax,nymax,nzmax,memind(numwfmem),m,ix,jy,ixp,jyp |
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55 | integer :: itime,itime1,itime2,level,indexh |
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56 | real :: yy1(0:nxmax-1,0:nymax-1,nzmax,numwfmem) |
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57 | real :: yy2(0:nxmax-1,0:nymax-1,nzmax,numwfmem) |
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58 | real :: yy3(0:nxmax-1,0:nymax-1,nzmax,numwfmem) |
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59 | real :: ddx,ddy,rddx,rddy,dt1,dt2,dt,y1(2),y2(2),y3(2) |
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60 | real :: xt,yt,yint1,yint2,yint3,p1,p2,p3,p4 |
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61 | integer :: iwftouse |
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62 | |
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63 | |
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64 | |
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65 | ! If point at border of grid -> small displacement into grid |
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66 | !*********************************************************** |
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67 | |
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68 | if (xt.ge.real(nx-1)) xt=real(nx-1)-0.00001 |
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69 | if (yt.ge.real(ny-1)) yt=real(ny-1)-0.00001 |
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70 | |
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71 | |
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72 | |
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73 | !********************************************************************** |
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74 | ! 1.) Bilinear horizontal interpolation |
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75 | ! This has to be done separately for 2 fields (Temporal) |
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76 | !******************************************************* |
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77 | |
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78 | ! Determine the lower left corner and its distance to the current position |
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79 | !************************************************************************* |
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80 | |
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81 | ix=int(xt) |
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82 | jy=int(yt) |
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83 | ixp=ix+1 |
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84 | jyp=jy+1 |
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85 | ddx=xt-real(ix) |
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86 | ddy=yt-real(jy) |
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87 | rddx=1.-ddx |
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88 | rddy=1.-ddy |
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89 | p1=rddx*rddy |
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90 | p2=ddx*rddy |
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91 | p3=rddx*ddy |
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92 | p4=ddx*ddy |
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93 | |
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94 | |
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95 | ! Loop over 2 time steps |
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96 | !*********************** |
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97 | |
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98 | ! do m=1,2 |
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99 | indexh=iwftouse |
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100 | |
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101 | y1(1)=p1*yy1(ix ,jy ,level,indexh) & |
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102 | + p2*yy1(ixp,jy ,level,indexh) & |
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103 | + p3*yy1(ix ,jyp,level,indexh) & |
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104 | + p4*yy1(ixp,jyp,level,indexh) |
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105 | y2(1)=p1*yy2(ix ,jy ,level,indexh) & |
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106 | + p2*yy2(ixp,jy ,level,indexh) & |
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107 | + p3*yy2(ix ,jyp,level,indexh) & |
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108 | + p4*yy2(ixp,jyp,level,indexh) |
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109 | y3(1)=p1*yy3(ix ,jy ,level,indexh) & |
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110 | + p2*yy3(ixp,jy ,level,indexh) & |
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111 | + p3*yy3(ix ,jyp,level,indexh) & |
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112 | + p4*yy3(ixp,jyp,level,indexh) |
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113 | ! end do |
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114 | |
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115 | |
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116 | !************************************ |
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117 | ! 2.) Temporal interpolation (linear) - skip to be consistent with clouds |
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118 | !************************************ |
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119 | |
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120 | ! dt1=real(itime-itime1) |
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121 | ! dt2=real(itime2-itime) |
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122 | ! dt=dt1+dt2 |
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123 | |
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124 | ! yint1=(y1(1)*dt2+y1(2)*dt1)/dt |
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125 | ! yint2=(y2(1)*dt2+y2(2)*dt1)/dt |
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126 | ! yint3=(y3(1)*dt2+y3(2)*dt1)/dt |
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127 | |
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128 | yint1=y1(1) |
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129 | yint2=y2(1) |
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130 | yint3=y3(1) |
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131 | |
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132 | end subroutine interpol_rain |
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