| 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 initialize(itime,ldt,up,vp,wp, & |
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| 5 | usigold,vsigold,wsigold,xt,yt,zt,icbt) |
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| 6 | ! i i o o o |
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| 7 | ! o o o i i i o |
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| 8 | !***************************************************************************** |
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| 9 | ! * |
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| 10 | ! Calculation of trajectories utilizing a zero-acceleration scheme. The time* |
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| 11 | ! step is determined by the Courant-Friedrichs-Lewy (CFL) criterion. This * |
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| 12 | ! means that the time step must be so small that the displacement within * |
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| 13 | ! this time step is smaller than 1 grid distance. Additionally, a temporal * |
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| 14 | ! CFL criterion is introduced: the time step must be smaller than the time * |
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| 15 | ! interval of the wind fields used for interpolation. * |
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| 16 | ! For random walk simulations, these are the only time step criteria. * |
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| 17 | ! For the other options, the time step is also limited by the Lagrangian * |
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| 18 | ! time scale. * |
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| 19 | ! * |
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| 20 | ! Author: A. Stohl * |
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| 21 | ! * |
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| 22 | ! 16 December 1997 * |
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| 23 | ! * |
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| 24 | ! Literature: * |
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| 25 | ! * |
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| 26 | !***************************************************************************** |
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| 27 | ! * |
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| 28 | ! Variables: * |
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| 29 | ! h [m] Mixing height * |
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| 30 | ! lwindinterv [s] time interval between two wind fields * |
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| 31 | ! itime [s] current temporal position * |
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| 32 | ! ldt [s] Suggested time step for next integration * |
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| 33 | ! ladvance [s] Total integration time period * |
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| 34 | ! rannumb(maxrand) normally distributed random variables * |
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| 35 | ! up,vp,wp random velocities due to turbulence * |
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| 36 | ! usig,vsig,wsig uncertainties of wind velocities due to interpolation * |
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| 37 | ! usigold,vsigold,wsigold like usig, etc., but for the last time step * |
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| 38 | ! xt,yt,zt Next time step's spatial position of trajectory * |
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| 39 | ! * |
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| 40 | ! * |
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| 41 | ! Constants: * |
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| 42 | ! cfl factor, by which the time step has to be smaller than * |
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| 43 | ! the spatial CFL-criterion * |
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| 44 | ! cflt factor, by which the time step has to be smaller than * |
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| 45 | ! the temporal CFL-criterion * |
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| 46 | ! * |
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| 47 | !***************************************************************************** |
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| 48 | |
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| 49 | use par_mod |
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| 50 | use com_mod |
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| 51 | use interpol_mod |
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| 52 | use hanna_mod |
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| 53 | use random_mod, only: ran3 |
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| 54 | |
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| 55 | implicit none |
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| 56 | |
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| 57 | integer :: itime |
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| 58 | integer :: ldt,nrand |
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| 59 | integer(kind=2) :: icbt |
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| 60 | real :: zt,dz,dz1,dz2,up,vp,wp,usigold,vsigold,wsigold |
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| 61 | real(kind=dp) :: xt,yt |
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| 62 | save idummy |
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| 63 | |
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| 64 | integer :: idummy = -7 |
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| 65 | |
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| 66 | icbt=1 ! initialize particle to "no reflection" |
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| 67 | |
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| 68 | nrand=int(ran3(idummy)*real(maxrand-1))+1 |
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| 69 | |
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| 70 | |
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| 71 | !****************************** |
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| 72 | ! 2. Interpolate necessary data |
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| 73 | !****************************** |
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| 74 | |
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| 75 | ! Compute maximum mixing height around particle position |
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| 76 | !******************************************************* |
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| 77 | |
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| 78 | ix=int(xt) |
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| 79 | jy=int(yt) |
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| 80 | ixp=ix+1 |
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| 81 | jyp=jy+1 |
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| 82 | |
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| 83 | h=max(hmix(ix ,jy,1,memind(1)), & |
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| 84 | hmix(ixp,jy ,1,memind(1)), & |
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| 85 | hmix(ix ,jyp,1,memind(1)), & |
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| 86 | hmix(ixp,jyp,1,memind(1)), & |
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| 87 | hmix(ix ,jy ,1,memind(2)), & |
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| 88 | hmix(ixp,jy ,1,memind(2)), & |
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| 89 | hmix(ix ,jyp,1,memind(2)), & |
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| 90 | hmix(ixp,jyp,1,memind(2))) |
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| 91 | |
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| 92 | zeta=zt/h |
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| 93 | |
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| 94 | |
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| 95 | !************************************************************* |
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| 96 | ! If particle is in the PBL, interpolate once and then make a |
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| 97 | ! time loop until end of interval is reached |
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| 98 | !************************************************************* |
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| 99 | |
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| 100 | if (zeta.le.1.) then |
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| 101 | |
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| 102 | call interpol_all(itime,real(xt),real(yt),zt) |
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| 103 | |
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| 104 | |
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| 105 | ! Vertical interpolation of u,v,w,rho and drhodz |
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| 106 | !*********************************************** |
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| 107 | |
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| 108 | ! Vertical distance to the level below and above current position |
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| 109 | ! both in terms of (u,v) and (w) fields |
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| 110 | !**************************************************************** |
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| 111 | |
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| 112 | dz1=zt-height(indz) |
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| 113 | dz2=height(indzp)-zt |
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| 114 | dz=1./(dz1+dz2) |
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| 115 | |
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| 116 | u=(dz1*uprof(indzp)+dz2*uprof(indz))*dz |
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| 117 | v=(dz1*vprof(indzp)+dz2*vprof(indz))*dz |
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| 118 | w=(dz1*wprof(indzp)+dz2*wprof(indz))*dz |
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| 119 | |
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| 120 | |
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| 121 | ! Compute the turbulent disturbances |
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| 122 | |
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| 123 | ! Determine the sigmas and the timescales |
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| 124 | !**************************************** |
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| 125 | |
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| 126 | if (turbswitch) then |
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| 127 | call hanna(zt) |
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| 128 | else |
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| 129 | call hanna1(zt) |
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| 130 | endif |
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| 131 | |
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| 132 | |
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| 133 | ! Determine the new diffusivity velocities |
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| 134 | !***************************************** |
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| 135 | |
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| 136 | if (nrand+2.gt.maxrand) nrand=1 |
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| 137 | up=rannumb(nrand)*sigu |
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| 138 | vp=rannumb(nrand+1)*sigv |
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| 139 | wp=rannumb(nrand+2) |
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| 140 | if (.not.turbswitch) then ! modified by mc |
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| 141 | wp=wp*sigw |
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| 142 | else if (cblflag.eq.1) then ! modified by mc |
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| 143 | if(-h/ol.gt.5) then |
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| 144 | !if (ol.lt.0.) then |
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| 145 | !if (ol.gt.0.) then !by mc : only for test correct is lt.0 |
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| 146 | call initialize_cbl_vel(idummy,zt,ust,wst,h,sigw,wp,ol) |
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| 147 | else |
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| 148 | wp=wp*sigw |
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| 149 | end if |
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| 150 | end if |
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| 151 | |
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| 152 | |
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| 153 | ! Determine time step for next integration |
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| 154 | !***************************************** |
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| 155 | |
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| 156 | if (turbswitch) then |
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| 157 | ldt=int(min(tlw,h/max(2.*abs(wp*sigw),1.e-5), & |
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| 158 | 0.5/abs(dsigwdz),600.)*ctl) |
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| 159 | else |
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| 160 | ldt=int(min(tlw,h/max(2.*abs(wp),1.e-5),600.)*ctl) |
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| 161 | endif |
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| 162 | ldt=max(ldt,mintime) |
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| 163 | |
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| 164 | |
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| 165 | usig=(usigprof(indzp)+usigprof(indz))/2. |
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| 166 | vsig=(vsigprof(indzp)+vsigprof(indz))/2. |
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| 167 | wsig=(wsigprof(indzp)+wsigprof(indz))/2. |
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| 168 | |
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| 169 | else |
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| 170 | |
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| 171 | |
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| 172 | |
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| 173 | !********************************************************** |
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| 174 | ! For all particles that are outside the PBL, make a single |
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| 175 | ! time step. Only horizontal turbulent disturbances are |
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| 176 | ! calculated. Vertical disturbances are reset. |
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| 177 | !********************************************************** |
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| 178 | |
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| 179 | |
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| 180 | ! Interpolate the wind |
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| 181 | !********************* |
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| 182 | |
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| 183 | call interpol_wind(itime,real(xt),real(yt),zt) |
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| 184 | |
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| 185 | |
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| 186 | ! Compute everything for above the PBL |
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| 187 | |
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| 188 | ! Assume constant turbulent perturbations |
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| 189 | !**************************************** |
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| 190 | |
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| 191 | ldt=abs(lsynctime) |
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| 192 | |
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| 193 | if (nrand+1.gt.maxrand) nrand=1 |
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| 194 | up=rannumb(nrand)*0.3 |
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| 195 | vp=rannumb(nrand+1)*0.3 |
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| 196 | nrand=nrand+2 |
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| 197 | wp=0. |
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| 198 | sigw=0. |
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| 199 | |
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| 200 | endif |
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| 201 | |
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| 202 | !**************************************************************** |
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| 203 | ! Add mesoscale random disturbances |
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| 204 | ! This is done only once for the whole lsynctime interval to save |
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| 205 | ! computation time |
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| 206 | !**************************************************************** |
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| 207 | |
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| 208 | |
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| 209 | ! It is assumed that the average interpolation error is 1/2 sigma |
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| 210 | ! of the surrounding points, autocorrelation time constant is |
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| 211 | ! 1/2 of time interval between wind fields |
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| 212 | !**************************************************************** |
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| 213 | |
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| 214 | if (nrand+2.gt.maxrand) nrand=1 |
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| 215 | usigold=rannumb(nrand)*usig |
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| 216 | vsigold=rannumb(nrand+1)*vsig |
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| 217 | wsigold=rannumb(nrand+2)*wsig |
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| 218 | |
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| 219 | end subroutine initialize |
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