1 | !*********************************************************************** |
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2 | !* Copyright 2012,2013 * |
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3 | !* Jerome Brioude, Delia Arnold, Andreas Stohl, Wayne Angevine, * |
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4 | !* John Burkhart, Massimo Cassiani, Adam Dingwell, Richard C Easter, Sabine Eckhardt,* |
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5 | !* Stephanie Evan, Jerome D Fast, Don Morton, Ignacio Pisso, * |
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6 | !* Petra Seibert, Gerard Wotawa, Caroline Forster, Harald Sodemann, * |
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7 | !* This file is part of FLEXPART WRF * |
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8 | !* * |
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9 | !* FLEXPART is free software: you can redistribute it and/or modify * |
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10 | !* it under the terms of the GNU General Public License as published by* |
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11 | !* the Free Software Foundation, either version 3 of the License, or * |
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12 | !* (at your option) any later version. * |
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13 | !* * |
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14 | !* FLEXPART is distributed in the hope that it will be useful, * |
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15 | !* but WITHOUT ANY WARRANTY; without even the implied warranty of * |
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16 | !* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * |
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17 | !* GNU General Public License for more details. * |
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18 | !* * |
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19 | !* You should have received a copy of the GNU General Public License * |
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20 | !* along with FLEXPART. If not, see <http://www.gnu.org/licenses/>. * |
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21 | !*********************************************************************** |
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22 | subroutine centerofmass(xl,yl,n,xcenter,ycenter) |
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23 | ! i i i o o |
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24 | !******************************************************************************* |
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25 | ! * |
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26 | ! Note: This is the FLEXPART_WRF version of subroutine assignland. * |
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27 | ! The computational grid is the WRF x-y grid rather than lat-lon. * |
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28 | ! * |
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29 | ! This routine calculates the center of mass of n points on the Earth. * |
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30 | ! Input are the longitudes (xl) and latitudes (yl) of the individual * |
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31 | ! points, output is the longitude and latitude of the centre of mass. * |
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32 | ! * |
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33 | ! Author: A. Stohl * |
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34 | ! * |
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35 | ! 24 January 2002 * |
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36 | ! * |
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37 | ! 26 Oct 2005, R. Easter - changes associated with WRF horizontal grid. * |
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38 | ! Since x & y coords are in meters, * |
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39 | ! so just sum/average the xl & yl. * |
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40 | ! * |
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41 | !******************************************************************************* |
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42 | |
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43 | use par_mod |
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44 | |
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45 | implicit none |
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46 | |
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47 | integer :: n,l |
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48 | real :: xl(n),yl(n),xll,yll,xav,yav,zav,x,y,z,xcenter,ycenter |
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49 | |
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50 | |
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51 | xav=0. |
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52 | yav=0. |
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53 | zav=0. |
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54 | |
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55 | do l=1,n |
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56 | |
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57 | ! Convert longitude and latitude from degrees to radians |
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58 | !******************************************************* |
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59 | |
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60 | ! for FLEXPART_WRF, x & y coords are in meters, |
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61 | ! so just sum/average the xl & yl |
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62 | ! xll=xl(l)*pi180 |
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63 | ! yll=yl(l)*pi180 |
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64 | |
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65 | ! Calculate 3D coordinates from longitude and latitude |
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66 | !***************************************************** |
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67 | |
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68 | ! for FLEXPART_WRF, this isn't necessary |
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69 | ! x = cos(yll)*sin(xll) |
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70 | ! y = -1.*cos(yll)*cos(xll) |
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71 | ! z = sin(yll) |
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72 | |
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73 | |
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74 | ! Find the mean location in Cartesian coordinates |
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75 | !************************************************ |
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76 | |
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77 | ! xav=xav+x |
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78 | ! yav=yav+y |
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79 | ! zav=zav+z |
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80 | xav=xav+xl(l) |
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81 | yav=yav+yl(l) |
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82 | |
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83 | enddo |
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84 | |
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85 | xav=xav/real(n) |
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86 | yav=yav/real(n) |
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87 | ! zav=zav/float(n) |
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88 | |
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89 | |
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90 | ! Project the point back onto Earth's surface |
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91 | !******************************************** |
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92 | |
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93 | ! for FLEXPART_WRF, this isn't necessary |
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94 | ! xcenter=atan2(xav,-1.*yav) |
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95 | ! ycenter=atan2(zav,sqrt(xav*xav+yav*yav)) |
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96 | |
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97 | ! Convert back to degrees |
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98 | !************************ |
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99 | |
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100 | ! for FLEXPART_WRF, this isn't necessary |
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101 | ! xcenter=xcenter/pi180 |
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102 | ! ycenter=ycenter/pi180 |
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103 | xcenter=xav |
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104 | ycenter=yav |
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105 | |
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106 | end subroutine centerofmass |
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107 | |
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