1 | !********************************************************************** |
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2 | ! Copyright 1998,1999,2000,2001,2002,2005,2007,2008,2009,2010 * |
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3 | ! Andreas Stohl, Petra Seibert, A. Frank, Gerhard Wotawa, * |
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4 | ! Caroline Forster, Sabine Eckhardt, John Burkhart, Harald Sodemann * |
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5 | ! * |
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6 | ! This file is part of FLEXPART. * |
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7 | ! * |
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8 | ! FLEXPART is free software: you can redistribute it and/or modify * |
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9 | ! it under the terms of the GNU General Public License as published by* |
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10 | ! the Free Software Foundation, either version 3 of the License, or * |
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11 | ! (at your option) any later version. * |
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12 | ! * |
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13 | ! FLEXPART is distributed in the hope that it will be useful, * |
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14 | ! but WITHOUT ANY WARRANTY; without even the implied warranty of * |
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15 | ! MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * |
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16 | ! GNU General Public License for more details. * |
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17 | ! * |
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18 | ! You should have received a copy of the GNU General Public License * |
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19 | ! along with FLEXPART. If not, see <http://www.gnu.org/licenses/>. * |
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20 | !********************************************************************** |
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21 | |
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22 | subroutine initialize(pj, itime,ldt,up,vp,wp, & |
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23 | usigold,vsigold,wsigold,xt,yt,zt,icbt) |
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24 | ! i i o o o |
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25 | ! o o o i i i o |
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26 | !***************************************************************************** |
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27 | ! * |
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28 | ! Calculation of trajectories utilizing a zero-acceleration scheme. The time* |
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29 | ! step is determined by the Courant-Friedrichs-Lewy (CFL) criterion. This * |
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30 | ! means that the time step must be so small that the displacement within * |
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31 | ! this time step is smaller than 1 grid distance. Additionally, a temporal * |
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32 | ! CFL criterion is introduced: the time step must be smaller than the time * |
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33 | ! interval of the wind fields used for interpolation. * |
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34 | ! For random walk simulations, these are the only time step criteria. * |
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35 | ! For the other options, the time step is also limited by the Lagrangian * |
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36 | ! time scale. * |
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37 | ! * |
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38 | ! Author: A. Stohl * |
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39 | ! * |
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40 | ! 16 December 1997 * |
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41 | ! * |
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42 | ! Literature: * |
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43 | ! * |
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44 | !***************************************************************************** |
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45 | ! * |
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46 | ! Variables: * |
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47 | ! h [m] Mixing height * |
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48 | ! lwindinterv [s] time interval between two wind fields * |
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49 | ! itime [s] current temporal position * |
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50 | ! ldt [s] Suggested time step for next integration * |
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51 | ! ladvance [s] Total integration time period * |
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52 | ! rannumb(maxrand) normally distributed random variables * |
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53 | ! up,vp,wp random velocities due to turbulence * |
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54 | ! usig,vsig,wsig uncertainties of wind velocities due to interpolation * |
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55 | ! usigold,vsigold,wsigold like usig, etc., but for the last time step * |
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56 | ! xt,yt,zt Next time step's spatial position of trajectory * |
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57 | ! * |
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58 | ! * |
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59 | ! Constants: * |
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60 | ! cfl factor, by which the time step has to be smaller than * |
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61 | ! the spatial CFL-criterion * |
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62 | ! cflt factor, by which the time step has to be smaller than * |
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63 | ! the temporal CFL-criterion * |
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64 | ! * |
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65 | !***************************************************************************** |
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66 | |
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67 | use par_mod |
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68 | use com_mod |
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69 | use interpol_mod |
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70 | use hanna_mod |
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71 | use random_mod, only : ran3_initialize |
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72 | ! reads: ran3_initialize |
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73 | ! writes: |
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74 | |
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75 | implicit none |
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76 | |
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77 | integer, intent(in) :: pj |
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78 | integer, intent(in) :: itime |
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79 | integer :: ldt,nrand |
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80 | integer(kind=2) :: icbt |
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81 | real :: zt,dz,dz1,dz2,up,vp,wp,usigold,vsigold,wsigold,ran3 |
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82 | real(kind=dp) :: xt,yt |
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83 | save idummy |
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84 | |
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85 | integer :: idummy = -7 |
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86 | |
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87 | icbt=1 ! initialize particle to "no reflection" |
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88 | |
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89 | nrand=int(ran3_initialize(pj)*real(maxrand-1))+1 |
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90 | |
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91 | |
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92 | !****************************** |
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93 | ! 2. Interpolate necessary data |
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94 | !****************************** |
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95 | |
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96 | ! Compute maximum mixing height around particle position |
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97 | !******************************************************* |
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98 | |
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99 | ix=int(xt) |
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100 | jy=int(yt) |
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101 | ixp=ix+1 |
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102 | jyp=jy+1 |
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103 | |
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104 | h=max(hmix(ix ,jy ,1,memind(1)), & |
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105 | hmix(ixp,jy ,1,memind(1)), & |
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106 | hmix(ix ,jyp,1,memind(1)), & |
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107 | hmix(ixp,jyp,1,memind(1)), & |
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108 | hmix(ix ,jy ,1,memind(2)), & |
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109 | hmix(ixp,jy ,1,memind(2)), & |
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110 | hmix(ix ,jyp,1,memind(2)), & |
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111 | hmix(ixp,jyp,1,memind(2))) |
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112 | |
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113 | zeta=zt/h |
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114 | |
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115 | |
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116 | !************************************************************* |
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117 | ! If particle is in the PBL, interpolate once and then make a |
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118 | ! time loop until end of interval is reached |
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119 | !************************************************************* |
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120 | |
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121 | if (zeta.le.1.) then |
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122 | |
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123 | call interpol_all(itime,real(xt),real(yt),zt) |
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124 | |
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125 | |
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126 | ! Vertical interpolation of u,v,w,rho and drhodz |
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127 | !*********************************************** |
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128 | |
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129 | ! Vertical distance to the level below and above current position |
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130 | ! both in terms of (u,v) and (w) fields |
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131 | !**************************************************************** |
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132 | |
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133 | dz1=zt-height(indz) |
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134 | dz2=height(indzp)-zt |
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135 | dz=1./(dz1+dz2) |
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136 | |
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137 | u=(dz1*uprof(indzp)+dz2*uprof(indz))*dz |
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138 | v=(dz1*vprof(indzp)+dz2*vprof(indz))*dz |
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139 | w=(dz1*wprof(indzp)+dz2*wprof(indz))*dz |
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140 | |
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141 | |
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142 | ! Compute the turbulent disturbances |
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143 | |
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144 | ! Determine the sigmas and the timescales |
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145 | !**************************************** |
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146 | |
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147 | if (turbswitch) then |
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148 | call hanna(zt) |
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149 | else |
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150 | call hanna1(zt) |
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151 | endif |
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152 | |
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153 | |
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154 | ! Determine the new diffusivity velocities |
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155 | !***************************************** |
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156 | |
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157 | if (nrand+2.gt.maxrand) nrand=1 |
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158 | up=rannumb(nrand)*sigu |
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159 | vp=rannumb(nrand+1)*sigv |
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160 | wp=rannumb(nrand+2) |
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161 | if (.not.turbswitch) wp=wp*sigw |
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162 | |
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163 | |
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164 | ! Determine time step for next integration |
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165 | !***************************************** |
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166 | |
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167 | if (turbswitch) then |
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168 | ldt=int(min(tlw,h/max(2.*abs(wp*sigw),1.e-5), & |
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169 | 0.5/abs(dsigwdz),600.)*ctl) |
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170 | else |
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171 | ldt=int(min(tlw,h/max(2.*abs(wp),1.e-5),600.)*ctl) |
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172 | endif |
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173 | ldt=max(ldt,mintime) |
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174 | |
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175 | |
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176 | usig=(usigprof(indzp)+usigprof(indz))/2. |
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177 | vsig=(vsigprof(indzp)+vsigprof(indz))/2. |
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178 | wsig=(wsigprof(indzp)+wsigprof(indz))/2. |
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179 | |
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180 | else |
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181 | |
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182 | |
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183 | |
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184 | !********************************************************** |
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185 | ! For all particles that are outside the PBL, make a single |
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186 | ! time step. Only horizontal turbulent disturbances are |
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187 | ! calculated. Vertical disturbances are reset. |
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188 | !********************************************************** |
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189 | |
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190 | |
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191 | ! Interpolate the wind |
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192 | !********************* |
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193 | |
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194 | call interpol_wind(itime,real(xt),real(yt),zt) |
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195 | |
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196 | |
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197 | ! Compute everything for above the PBL |
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198 | |
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199 | ! Assume constant turbulent perturbations |
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200 | !**************************************** |
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201 | |
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202 | ldt=abs(lsynctime) |
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203 | |
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204 | if (nrand+1.gt.maxrand) nrand=1 |
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205 | up=rannumb(nrand)*0.3 |
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206 | vp=rannumb(nrand+1)*0.3 |
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207 | nrand=nrand+2 |
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208 | wp=0. |
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209 | sigw=0. |
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210 | |
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211 | endif |
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212 | |
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213 | !**************************************************************** |
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214 | ! Add mesoscale random disturbances |
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215 | ! This is done only once for the whole lsynctime interval to save |
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216 | ! computation time |
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217 | !**************************************************************** |
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218 | |
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219 | |
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220 | ! It is assumed that the average interpolation error is 1/2 sigma |
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221 | ! of the surrounding points, autocorrelation time constant is |
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222 | ! 1/2 of time interval between wind fields |
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223 | !**************************************************************** |
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224 | |
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225 | if (nrand+2.gt.maxrand) nrand=1 |
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226 | usigold=rannumb(nrand)*usig |
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227 | vsigold=rannumb(nrand+1)*vsig |
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228 | wsigold=rannumb(nrand+2)*wsig |
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229 | |
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230 | end subroutine initialize |
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