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 windalign(u,v,ffap,ffcp,ux,vy) |
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23 | ! i i i i o o |
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24 | !***************************************************************************** |
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25 | ! * |
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26 | ! Transformation from along- and cross-wind components to u and v * |
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27 | ! components. * |
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28 | ! * |
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29 | ! Author: A. Stohl * |
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30 | ! * |
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31 | ! 3 June 1996 * |
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32 | ! * |
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33 | !***************************************************************************** |
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34 | ! * |
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35 | ! Variables: * |
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36 | ! ffap turbulent wind in along wind direction * |
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37 | ! ffcp turbulent wind in cross wind direction * |
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38 | ! u main wind component in x direction * |
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39 | ! ux turbulent wind in x direction * |
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40 | ! v main wind component in y direction * |
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41 | ! vy turbulent wind in y direction * |
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42 | ! * |
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43 | !***************************************************************************** |
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44 | |
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45 | implicit none |
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46 | |
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47 | real :: u,v,ffap,ffcp,ux,vy,ffinv,ux1,ux2,vy1,vy2,sinphi,cosphi |
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48 | real,parameter :: eps=1.e-30 |
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49 | |
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50 | |
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51 | ! Transform along wind components |
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52 | !******************************** |
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53 | |
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54 | ffinv=1./max(sqrt(u*u+v*v),eps) |
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55 | sinphi=v*ffinv |
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56 | vy1=sinphi*ffap |
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57 | cosphi=u*ffinv |
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58 | ux1=cosphi*ffap |
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59 | |
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60 | |
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61 | ! Transform cross wind components |
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62 | !******************************** |
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63 | |
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64 | ux2=-sinphi*ffcp |
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65 | vy2=cosphi*ffcp |
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66 | |
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67 | |
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68 | ! Add contributions from along and cross wind components |
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69 | !******************************************************* |
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70 | |
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71 | ux=ux1+ux2 |
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72 | vy=vy1+vy2 |
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73 | |
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74 | end subroutine windalign |
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