| 1 | subroutine interpol_wind_nests(itime,xt,yt,zt) |
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| 2 | ! i i i i |
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| 3 | !***************************************************************************** |
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| 4 | ! * |
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| 5 | ! This subroutine interpolates the wind data to current trajectory position.* |
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| 6 | ! * |
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| 7 | ! Author: A. Stohl * |
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| 8 | ! * |
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| 9 | ! 16 December 1997 * |
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| 10 | ! 16 December 1997 * |
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| 11 | ! * |
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| 12 | ! Revision March 2005 by AST : all output variables in common block cal- * |
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| 13 | ! culation of standard deviation done in this * |
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| 14 | ! routine rather than subroutine call in order * |
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| 15 | ! to save computation time * |
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| 16 | ! * |
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| 17 | !***************************************************************************** |
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| 18 | ! * |
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| 19 | ! Variables: * |
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| 20 | ! u,v,w wind components * |
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| 21 | ! itime [s] current temporal position * |
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| 22 | ! memtime(3) [s] times of the wind fields in memory * |
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| 23 | ! xt,yt,zt coordinates position for which wind data shall be * |
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| 24 | ! calculated * |
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| 25 | ! * |
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| 26 | ! Constants: * |
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| 27 | ! * |
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| 28 | !***************************************************************************** |
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| 29 | |
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| 30 | use par_mod |
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| 31 | use com_mod |
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| 32 | use interpol_mod |
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| 33 | |
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| 34 | implicit none |
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| 35 | |
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| 36 | integer :: itime |
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| 37 | real :: xt,yt,zt |
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| 38 | |
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| 39 | ! Auxiliary variables needed for interpolation |
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| 40 | real :: dz1,dz2,dz |
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| 41 | real :: u1(2),v1(2),w1(2),uh(2),vh(2),wh(2) |
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| 42 | real :: usl,vsl,wsl,usq,vsq,wsq,xaux |
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| 43 | integer :: i,m,n,indexh,indzh |
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| 44 | real,parameter :: eps=1.0e-30 |
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| 45 | |
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| 46 | |
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| 47 | !******************************************** |
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| 48 | ! Multilinear interpolation in time and space |
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| 49 | !******************************************** |
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| 50 | |
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| 51 | ! Determine the lower left corner and its distance to the current position |
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| 52 | !************************************************************************* |
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| 53 | |
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| 54 | ddx=xt-real(ix) |
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| 55 | ddy=yt-real(jy) |
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| 56 | rddx=1.-ddx |
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| 57 | rddy=1.-ddy |
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| 58 | p1=rddx*rddy |
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| 59 | p2=ddx*rddy |
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| 60 | p3=rddx*ddy |
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| 61 | p4=ddx*ddy |
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| 62 | |
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| 63 | ! Calculate variables for time interpolation |
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| 64 | !******************************************* |
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| 65 | |
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| 66 | dt1=real(itime-memtime(1)) |
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| 67 | dt2=real(memtime(2)-itime) |
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| 68 | dtt=1./(dt1+dt2) |
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| 69 | |
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| 70 | ! Determine the level below the current position for u,v |
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| 71 | !******************************************************* |
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| 72 | |
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| 73 | do i=2,nz |
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| 74 | if (height(i).gt.zt) then |
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| 75 | indz=i-1 |
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| 76 | goto 6 |
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| 77 | endif |
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| 78 | end do |
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| 79 | 6 continue |
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| 80 | |
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| 81 | |
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| 82 | ! Vertical distance to the level below and above current position |
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| 83 | !**************************************************************** |
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| 84 | |
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| 85 | dz=1./(height(indz+1)-height(indz)) |
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| 86 | dz1=(zt-height(indz))*dz |
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| 87 | dz2=(height(indz+1)-zt)*dz |
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| 88 | |
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| 89 | |
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| 90 | !********************************************************************** |
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| 91 | ! 1.) Bilinear horizontal interpolation |
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| 92 | ! This has to be done separately for 6 fields (Temporal(2)*Vertical(3)) |
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| 93 | !********************************************************************** |
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| 94 | |
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| 95 | ! Loop over 2 time steps and 2 levels |
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| 96 | !************************************ |
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| 97 | |
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| 98 | usl=0. |
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| 99 | vsl=0. |
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| 100 | wsl=0. |
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| 101 | usq=0. |
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| 102 | vsq=0. |
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| 103 | wsq=0. |
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| 104 | do m=1,2 |
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| 105 | indexh=memind(m) |
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| 106 | do n=1,2 |
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| 107 | indzh=indz+n-1 |
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| 108 | |
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| 109 | u1(n)=p1*uun(ix ,jy ,indzh,indexh,ngrid) & |
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| 110 | +p2*uun(ixp,jy ,indzh,indexh,ngrid) & |
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| 111 | +p3*uun(ix ,jyp,indzh,indexh,ngrid) & |
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| 112 | +p4*uun(ixp,jyp,indzh,indexh,ngrid) |
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| 113 | v1(n)=p1*vvn(ix ,jy ,indzh,indexh,ngrid) & |
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| 114 | +p2*vvn(ixp,jy ,indzh,indexh,ngrid) & |
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| 115 | +p3*vvn(ix ,jyp,indzh,indexh,ngrid) & |
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| 116 | +p4*vvn(ixp,jyp,indzh,indexh,ngrid) |
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| 117 | w1(n)=p1*wwn(ix ,jy ,indzh,indexh,ngrid) & |
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| 118 | +p2*wwn(ixp,jy ,indzh,indexh,ngrid) & |
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| 119 | +p3*wwn(ix ,jyp,indzh,indexh,ngrid) & |
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| 120 | +p4*wwn(ixp,jyp,indzh,indexh,ngrid) |
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| 121 | |
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| 122 | usl=usl+uun(ix ,jy ,indzh,indexh,ngrid)+ & |
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| 123 | uun(ixp,jy ,indzh,indexh,ngrid) & |
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| 124 | +uun(ix ,jyp,indzh,indexh,ngrid)+ & |
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| 125 | uun(ixp,jyp,indzh,indexh,ngrid) |
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| 126 | vsl=vsl+vvn(ix ,jy ,indzh,indexh,ngrid)+ & |
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| 127 | vvn(ixp,jy ,indzh,indexh,ngrid) & |
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| 128 | +vvn(ix ,jyp,indzh,indexh,ngrid)+ & |
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| 129 | vvn(ixp,jyp,indzh,indexh,ngrid) |
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| 130 | wsl=wsl+wwn(ix ,jy ,indzh,indexh,ngrid)+ & |
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| 131 | wwn(ixp,jy ,indzh,indexh,ngrid) & |
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| 132 | +wwn(ix ,jyp,indzh,indexh,ngrid)+ & |
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| 133 | wwn(ixp,jyp,indzh,indexh,ngrid) |
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| 134 | |
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| 135 | usq=usq+uun(ix ,jy ,indzh,indexh,ngrid)* & |
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| 136 | uun(ix ,jy ,indzh,indexh,ngrid)+ & |
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| 137 | uun(ixp,jy ,indzh,indexh,ngrid)*uun(ixp,jy ,indzh,indexh,ngrid)+ & |
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| 138 | uun(ix ,jyp,indzh,indexh,ngrid)*uun(ix ,jyp,indzh,indexh,ngrid)+ & |
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| 139 | uun(ixp,jyp,indzh,indexh,ngrid)*uun(ixp,jyp,indzh,indexh,ngrid) |
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| 140 | vsq=vsq+vvn(ix ,jy ,indzh,indexh,ngrid)* & |
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| 141 | vvn(ix ,jy ,indzh,indexh,ngrid)+ & |
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| 142 | vvn(ixp,jy ,indzh,indexh,ngrid)*vvn(ixp,jy ,indzh,indexh,ngrid)+ & |
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| 143 | vvn(ix ,jyp,indzh,indexh,ngrid)*vvn(ix ,jyp,indzh,indexh,ngrid)+ & |
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| 144 | vvn(ixp,jyp,indzh,indexh,ngrid)*vvn(ixp,jyp,indzh,indexh,ngrid) |
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| 145 | wsq=wsq+wwn(ix ,jy ,indzh,indexh,ngrid)* & |
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| 146 | wwn(ix ,jy ,indzh,indexh,ngrid)+ & |
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| 147 | wwn(ixp,jy ,indzh,indexh,ngrid)*wwn(ixp,jy ,indzh,indexh,ngrid)+ & |
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| 148 | wwn(ix ,jyp,indzh,indexh,ngrid)*wwn(ix ,jyp,indzh,indexh,ngrid)+ & |
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| 149 | wwn(ixp,jyp,indzh,indexh,ngrid)*wwn(ixp,jyp,indzh,indexh,ngrid) |
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| 150 | end do |
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| 151 | |
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| 152 | |
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| 153 | !********************************** |
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| 154 | ! 2.) Linear vertical interpolation |
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| 155 | !********************************** |
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| 156 | |
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| 157 | uh(m)=dz2*u1(1)+dz1*u1(2) |
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| 158 | vh(m)=dz2*v1(1)+dz1*v1(2) |
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| 159 | wh(m)=dz2*w1(1)+dz1*w1(2) |
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| 160 | end do |
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| 161 | |
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| 162 | |
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| 163 | !************************************ |
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| 164 | ! 3.) Temporal interpolation (linear) |
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| 165 | !************************************ |
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| 166 | |
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| 167 | u=(uh(1)*dt2+uh(2)*dt1)*dtt |
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| 168 | v=(vh(1)*dt2+vh(2)*dt1)*dtt |
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| 169 | w=(wh(1)*dt2+wh(2)*dt1)*dtt |
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| 170 | |
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| 171 | |
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| 172 | ! Compute standard deviations |
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| 173 | !**************************** |
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| 174 | |
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| 175 | xaux=usq-usl*usl/16. |
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| 176 | if (xaux.lt.eps) then |
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| 177 | usig=0. |
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| 178 | else |
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| 179 | usig=sqrt(xaux/15.) |
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| 180 | endif |
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| 181 | |
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| 182 | xaux=vsq-vsl*vsl/16. |
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| 183 | if (xaux.lt.eps) then |
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| 184 | vsig=0. |
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| 185 | else |
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| 186 | vsig=sqrt(xaux/15.) |
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| 187 | endif |
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| 188 | |
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| 189 | |
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| 190 | xaux=wsq-wsl*wsl/16. |
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| 191 | if (xaux.lt.eps) then |
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| 192 | wsig=0. |
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| 193 | else |
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| 194 | wsig=sqrt(xaux/15.) |
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| 195 | endif |
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| 196 | |
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| 197 | end subroutine interpol_wind_nests |
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