[2352] | 1 | !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! |
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| 2 | ! |
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| 3 | ! this module contains necessary routines for performing an |
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| 4 | ! interpolation using a distance-weighted average of n nearest |
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| 5 | ! neighbors. |
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| 6 | ! |
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| 7 | !----------------------------------------------------------------------- |
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| 8 | ! |
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[9499] | 9 | ! CVS:$Id$ |
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[2352] | 10 | ! |
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| 11 | ! Copyright (c) 1997, 1998 the Regents of the University of |
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| 12 | ! California. |
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| 13 | ! |
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| 14 | ! This software and ancillary information (herein called software) |
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| 15 | ! called SCRIP is made available under the terms described here. |
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| 16 | ! The software has been approved for release with associated |
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| 17 | ! LA-CC Number 98-45. |
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| 18 | ! |
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| 19 | ! Unless otherwise indicated, this software has been authored |
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| 20 | ! by an employee or employees of the University of California, |
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| 21 | ! operator of the Los Alamos National Laboratory under Contract |
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| 22 | ! No. W-7405-ENG-36 with the U.S. Department of Energy. The U.S. |
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| 23 | ! Government has rights to use, reproduce, and distribute this |
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| 24 | ! software. The public may copy and use this software without |
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| 25 | ! charge, provided that this Notice and any statement of authorship |
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| 26 | ! are reproduced on all copies. Neither the Government nor the |
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| 27 | ! University makes any warranty, express or implied, or assumes |
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| 28 | ! any liability or responsibility for the use of this software. |
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| 29 | ! |
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| 30 | ! If software is modified to produce derivative works, such modified |
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| 31 | ! software should be clearly marked, so as not to confuse it with |
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| 32 | ! the version available from Los Alamos National Laboratory. |
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| 33 | ! |
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| 34 | !*********************************************************************** |
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| 35 | |
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| 36 | module remap_distance_weight |
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| 37 | |
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| 38 | !----------------------------------------------------------------------- |
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| 39 | |
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| 40 | use kinds_mod ! defines common data types |
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| 41 | use constants ! defines common constants |
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| 42 | use grids ! module containing grid info |
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| 43 | use remap_vars ! module containing remap info |
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| 44 | |
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| 45 | implicit none |
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| 46 | |
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| 47 | !----------------------------------------------------------------------- |
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| 48 | ! |
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| 49 | ! module variables |
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| 50 | ! |
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| 51 | !----------------------------------------------------------------------- |
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| 52 | |
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| 53 | integer (kind=int_kind), parameter :: & |
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| 54 | num_neighbors=4 ! num nearest neighbors to interpolate from |
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| 55 | |
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| 56 | real (kind=dbl_kind), dimension(:), allocatable, save :: & |
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| 57 | coslat, sinlat, & ! cosine, sine of grid lats (for distance) |
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| 58 | coslon, sinlon, & ! cosine, sine of grid lons (for distance) |
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| 59 | wgtstmp ! an array to hold the link weight |
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| 60 | |
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| 61 | !*********************************************************************** |
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| 62 | |
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| 63 | contains |
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| 64 | |
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| 65 | !*********************************************************************** |
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| 66 | |
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| 67 | subroutine remap_distwgt |
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| 68 | |
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| 69 | !----------------------------------------------------------------------- |
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| 70 | ! |
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| 71 | ! this routine computes the inverse-distance weights for a |
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| 72 | ! nearest-neighbor interpolation. |
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| 73 | ! |
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| 74 | !----------------------------------------------------------------------- |
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| 75 | |
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| 76 | !----------------------------------------------------------------------- |
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| 77 | ! |
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| 78 | ! local variables |
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| 79 | ! |
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| 80 | !----------------------------------------------------------------------- |
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| 81 | |
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| 82 | logical (kind=log_kind), dimension(num_neighbors) :: & |
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| 83 | nbr_mask ! mask at nearest neighbors |
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| 84 | |
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| 85 | integer (kind=int_kind) :: n, & |
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| 86 | dst_add, & ! destination address |
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| 87 | nmap ! index of current map being computed |
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| 88 | |
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| 89 | integer (kind=int_kind), dimension(num_neighbors) :: & |
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| 90 | nbr_add ! source address at nearest neighbors |
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| 91 | |
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| 92 | real (kind=dbl_kind), dimension(num_neighbors) :: & |
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| 93 | nbr_dist ! angular distance four nearest neighbors |
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| 94 | |
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| 95 | real (kind=dbl_kind) :: & |
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| 96 | coslat_dst, & ! cos(lat) of destination grid point |
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| 97 | coslon_dst, & ! cos(lon) of destination grid point |
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| 98 | sinlat_dst, & ! sin(lat) of destination grid point |
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| 99 | sinlon_dst, & ! sin(lon) of destination grid point |
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| 100 | dist_tot ! sum of neighbor distances (for normalizing) |
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| 101 | |
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| 102 | !----------------------------------------------------------------------- |
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| 103 | ! |
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| 104 | ! compute mappings from grid1 to grid2 |
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| 105 | ! |
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| 106 | !----------------------------------------------------------------------- |
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| 107 | |
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| 108 | nmap = 1 |
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| 109 | |
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| 110 | !*** |
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| 111 | !*** allocate wgtstmp to be consistent with store_link interface |
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| 112 | !*** |
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| 113 | |
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| 114 | allocate (wgtstmp(num_wts)) |
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| 115 | |
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| 116 | !*** |
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| 117 | !*** compute cos, sin of lat/lon on source grid for distance |
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| 118 | !*** calculations |
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| 119 | !*** |
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| 120 | |
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| 121 | allocate (coslat(grid1_size), coslon(grid1_size), & |
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| 122 | sinlat(grid1_size), sinlon(grid1_size)) |
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| 123 | |
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| 124 | coslat = cos(grid1_center_lat) |
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| 125 | coslon = cos(grid1_center_lon) |
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| 126 | sinlat = sin(grid1_center_lat) |
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| 127 | sinlon = sin(grid1_center_lon) |
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| 128 | |
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| 129 | !*** |
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| 130 | !*** loop over destination grid |
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| 131 | !*** |
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| 132 | |
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| 133 | grid_loop1: do dst_add = 1, grid2_size |
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| 134 | |
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| 135 | if (.not. grid2_mask(dst_add)) cycle grid_loop1 |
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| 136 | |
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| 137 | coslat_dst = cos(grid2_center_lat(dst_add)) |
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| 138 | coslon_dst = cos(grid2_center_lon(dst_add)) |
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| 139 | sinlat_dst = sin(grid2_center_lat(dst_add)) |
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| 140 | sinlon_dst = sin(grid2_center_lon(dst_add)) |
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| 141 | |
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| 142 | !*** |
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| 143 | !*** find nearest grid points on source grid and |
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| 144 | !*** distances to each point |
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| 145 | !*** |
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| 146 | |
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| 147 | call grid_search_nbr(nbr_add, nbr_dist, & |
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| 148 | grid2_center_lat(dst_add), & |
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| 149 | grid2_center_lon(dst_add), & |
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| 150 | coslat_dst, coslon_dst, & |
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| 151 | sinlat_dst, sinlon_dst, & |
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| 152 | bin_addr1, bin_addr2) |
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| 153 | |
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| 154 | !*** |
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| 155 | !*** compute weights based on inverse distance |
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| 156 | !*** if mask is false, eliminate those points |
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| 157 | !*** |
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| 158 | |
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| 159 | dist_tot = zero |
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| 160 | do n=1,num_neighbors |
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| 161 | if (grid1_mask(nbr_add(n))) then |
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| 162 | nbr_dist(n) = one/nbr_dist(n) |
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| 163 | dist_tot = dist_tot + nbr_dist(n) |
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| 164 | nbr_mask(n) = .true. |
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| 165 | else |
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| 166 | nbr_mask(n) = .false. |
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| 167 | endif |
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| 168 | end do |
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| 169 | |
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| 170 | !*** |
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| 171 | !*** normalize weights and store the link |
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| 172 | !*** |
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| 173 | |
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| 174 | do n=1,num_neighbors |
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| 175 | if (nbr_mask(n)) then |
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| 176 | wgtstmp(1) = nbr_dist(n)/dist_tot |
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| 177 | call store_link_nbr(nbr_add(n), dst_add, wgtstmp, nmap) |
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| 178 | grid2_frac(dst_add) = one |
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| 179 | endif |
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| 180 | end do |
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| 181 | |
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| 182 | end do grid_loop1 |
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| 183 | |
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| 184 | deallocate (coslat, coslon, sinlat, sinlon) |
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| 185 | |
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| 186 | !----------------------------------------------------------------------- |
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| 187 | ! |
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| 188 | ! compute mappings from grid2 to grid1 if necessary |
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| 189 | ! |
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| 190 | !----------------------------------------------------------------------- |
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| 191 | |
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| 192 | if (num_maps > 1) then |
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| 193 | |
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| 194 | nmap = 2 |
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| 195 | |
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| 196 | !*** |
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| 197 | !*** compute cos, sin of lat/lon on source grid for distance |
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| 198 | !*** calculations |
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| 199 | !*** |
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| 200 | |
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| 201 | allocate (coslat(grid2_size), coslon(grid2_size), & |
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| 202 | sinlat(grid2_size), sinlon(grid2_size)) |
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| 203 | |
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| 204 | coslat = cos(grid2_center_lat) |
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| 205 | coslon = cos(grid2_center_lon) |
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| 206 | sinlat = sin(grid2_center_lat) |
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| 207 | sinlon = sin(grid2_center_lon) |
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| 208 | |
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| 209 | !*** |
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| 210 | !*** loop over destination grid |
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| 211 | !*** |
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| 212 | |
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| 213 | grid_loop2: do dst_add = 1, grid1_size |
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| 214 | |
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| 215 | if (.not. grid1_mask(dst_add)) cycle grid_loop2 |
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| 216 | |
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| 217 | coslat_dst = cos(grid1_center_lat(dst_add)) |
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| 218 | coslon_dst = cos(grid1_center_lon(dst_add)) |
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| 219 | sinlat_dst = sin(grid1_center_lat(dst_add)) |
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| 220 | sinlon_dst = sin(grid1_center_lon(dst_add)) |
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| 221 | |
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| 222 | !*** |
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| 223 | !*** find four nearest grid points on source grid and |
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| 224 | !*** distances to each point |
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| 225 | !*** |
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| 226 | |
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| 227 | call grid_search_nbr(nbr_add, nbr_dist, & |
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| 228 | grid1_center_lat(dst_add), & |
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| 229 | grid1_center_lon(dst_add), & |
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| 230 | coslat_dst, coslon_dst, & |
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| 231 | sinlat_dst, sinlon_dst, & |
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| 232 | bin_addr2, bin_addr1) |
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| 233 | |
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| 234 | !*** |
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| 235 | !*** compute weights based on inverse distance |
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| 236 | !*** if mask is false, eliminate those points |
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| 237 | !*** |
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| 238 | |
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| 239 | dist_tot = zero |
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| 240 | do n=1,num_neighbors |
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| 241 | if (grid2_mask(nbr_add(n))) then |
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| 242 | nbr_dist(n) = one/nbr_dist(n) |
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| 243 | dist_tot = dist_tot + nbr_dist(n) |
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| 244 | nbr_mask(n) = .true. |
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| 245 | else |
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| 246 | nbr_mask(n) = .false. |
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| 247 | endif |
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| 248 | end do |
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| 249 | |
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| 250 | !*** |
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| 251 | !*** normalize weights and store the link |
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| 252 | !*** |
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| 253 | |
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| 254 | do n=1,num_neighbors |
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| 255 | if (nbr_mask(n)) then |
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| 256 | wgtstmp(1) = nbr_dist(n)/dist_tot |
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| 257 | call store_link_nbr(dst_add, nbr_add(n), wgtstmp, nmap) |
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| 258 | grid1_frac(dst_add) = one |
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| 259 | endif |
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| 260 | end do |
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| 261 | |
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| 262 | end do grid_loop2 |
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| 263 | |
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| 264 | deallocate (coslat, coslon, sinlat, sinlon) |
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| 265 | |
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| 266 | endif |
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| 267 | |
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| 268 | deallocate(wgtstmp) |
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| 269 | |
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| 270 | !----------------------------------------------------------------------- |
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| 271 | |
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| 272 | end subroutine remap_distwgt |
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| 273 | |
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| 274 | !*********************************************************************** |
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| 275 | |
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| 276 | subroutine grid_search_nbr(nbr_add, nbr_dist, plat, plon, & |
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| 277 | coslat_dst, coslon_dst, sinlat_dst, sinlon_dst, & |
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| 278 | src_bin_add, dst_bin_add) |
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| 279 | |
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| 280 | !----------------------------------------------------------------------- |
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| 281 | ! |
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| 282 | ! this routine finds the closest num_neighbor points to a search |
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| 283 | ! point and computes a distance to each of the neighbors. |
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| 284 | ! |
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| 285 | !----------------------------------------------------------------------- |
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| 286 | |
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| 287 | !----------------------------------------------------------------------- |
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| 288 | ! |
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| 289 | ! output variables |
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| 290 | ! |
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| 291 | !----------------------------------------------------------------------- |
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| 292 | |
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| 293 | integer (kind=int_kind), dimension(num_neighbors), intent(out) :: & |
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| 294 | nbr_add ! address of each of the closest points |
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| 295 | |
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| 296 | real (kind=dbl_kind), dimension(num_neighbors), intent(out) :: & |
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| 297 | nbr_dist ! distance to each of the closest points |
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| 298 | |
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| 299 | !----------------------------------------------------------------------- |
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| 300 | ! |
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| 301 | ! input variables |
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| 302 | ! |
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| 303 | !----------------------------------------------------------------------- |
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| 304 | |
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| 305 | integer (kind=int_kind), dimension(:,:), intent(in) :: & |
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| 306 | src_bin_add, & ! search bins for restricting search |
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| 307 | dst_bin_add |
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| 308 | |
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| 309 | real (kind=dbl_kind), intent(in) :: & |
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| 310 | plat, & ! latitude of the search point |
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| 311 | plon, & ! longitude of the search point |
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| 312 | coslat_dst, & ! cos(lat) of the search point |
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| 313 | coslon_dst, & ! cos(lon) of the search point |
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| 314 | sinlat_dst, & ! sin(lat) of the search point |
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| 315 | sinlon_dst ! sin(lon) of the search point |
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| 316 | |
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| 317 | !----------------------------------------------------------------------- |
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| 318 | ! |
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| 319 | ! local variables |
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| 320 | ! |
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| 321 | !----------------------------------------------------------------------- |
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| 322 | |
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| 323 | integer (kind=int_kind) :: n, nmax, nadd, nchk, & ! dummy indices |
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| 324 | min_add, max_add, nm1, np1, i, j, ip1, im1, jp1, jm1 |
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| 325 | |
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| 326 | real (kind=dbl_kind) :: & |
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| 327 | distance ! angular distance |
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| 328 | |
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| 329 | !----------------------------------------------------------------------- |
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| 330 | ! |
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| 331 | ! loop over source grid and find nearest neighbors |
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| 332 | ! |
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| 333 | !----------------------------------------------------------------------- |
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| 334 | |
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| 335 | !*** |
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| 336 | !*** restrict the search using search bins |
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| 337 | !*** expand the bins to catch neighbors |
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| 338 | !*** |
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| 339 | |
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| 340 | select case (restrict_type) |
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| 341 | case('latitude') |
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| 342 | |
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| 343 | do n=1,num_srch_bins |
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| 344 | if (plat >= bin_lats(1,n) .and. plat <= bin_lats(2,n)) then |
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| 345 | min_add = src_bin_add(1,n) |
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| 346 | max_add = src_bin_add(2,n) |
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| 347 | |
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| 348 | nm1 = max(n-1,1) |
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| 349 | np1 = min(n+1,num_srch_bins) |
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| 350 | |
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| 351 | min_add = min(min_add,src_bin_add(1,nm1)) |
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| 352 | max_add = max(max_add,src_bin_add(2,nm1)) |
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| 353 | min_add = min(min_add,src_bin_add(1,np1)) |
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| 354 | max_add = max(max_add,src_bin_add(2,np1)) |
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| 355 | endif |
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| 356 | end do |
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| 357 | |
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| 358 | case('latlon') |
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| 359 | |
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| 360 | n = 0 |
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| 361 | nmax = nint(sqrt(real(num_srch_bins))) |
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| 362 | do j=1,nmax |
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| 363 | jp1 = min(j+1,nmax) |
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| 364 | jm1 = max(j-1,1) |
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| 365 | do i=1,nmax |
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| 366 | ip1 = min(i+1,nmax) |
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| 367 | im1 = max(i-1,1) |
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| 368 | |
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| 369 | n = n+1 |
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| 370 | if (plat >= bin_lats(1,n) .and. plat <= bin_lats(2,n) .and. & |
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| 371 | plon >= bin_lons(1,n) .and. plon <= bin_lons(3,n)) then |
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| 372 | min_add = src_bin_add(1,n) |
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| 373 | max_add = src_bin_add(2,n) |
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| 374 | |
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| 375 | nm1 = (jm1-1)*nmax + im1 |
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| 376 | np1 = (jp1-1)*nmax + ip1 |
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| 377 | nm1 = max(nm1,1) |
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| 378 | np1 = min(np1,num_srch_bins) |
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| 379 | |
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| 380 | min_add = min(min_add,src_bin_add(1,nm1)) |
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| 381 | max_add = max(max_add,src_bin_add(2,nm1)) |
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| 382 | min_add = min(min_add,src_bin_add(1,np1)) |
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| 383 | max_add = max(max_add,src_bin_add(2,np1)) |
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| 384 | endif |
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| 385 | end do |
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| 386 | end do |
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| 387 | |
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| 388 | end select |
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| 389 | |
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| 390 | !*** |
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| 391 | !*** initialize distance and address arrays |
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| 392 | !*** |
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| 393 | |
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| 394 | nbr_add = 0 |
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| 395 | nbr_dist = bignum |
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| 396 | |
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| 397 | do nadd=min_add,max_add |
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| 398 | |
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| 399 | !*** |
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| 400 | !*** find distance to this point |
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| 401 | !*** |
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| 402 | |
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| 403 | distance = acos(sinlat_dst*sinlat(nadd) + & |
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| 404 | coslat_dst*coslat(nadd)* & |
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| 405 | (coslon_dst*coslon(nadd) + & |
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| 406 | sinlon_dst*sinlon(nadd)) ) |
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| 407 | |
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| 408 | !*** |
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| 409 | !*** store the address and distance if this is one of the |
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| 410 | !*** smallest four so far |
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| 411 | !*** |
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| 412 | |
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| 413 | check_loop: do nchk=1,num_neighbors |
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| 414 | if (distance .lt. nbr_dist(nchk)) then |
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| 415 | do n=num_neighbors,nchk+1,-1 |
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| 416 | nbr_add(n) = nbr_add(n-1) |
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| 417 | nbr_dist(n) = nbr_dist(n-1) |
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| 418 | end do |
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| 419 | nbr_add(nchk) = nadd |
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| 420 | nbr_dist(nchk) = distance |
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| 421 | exit check_loop |
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| 422 | endif |
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| 423 | end do check_loop |
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| 424 | |
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| 425 | end do |
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| 426 | |
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| 427 | !----------------------------------------------------------------------- |
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| 428 | |
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| 429 | end subroutine grid_search_nbr |
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| 430 | |
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| 431 | !*********************************************************************** |
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| 432 | |
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| 433 | subroutine store_link_nbr(add1, add2, weights, nmap) |
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| 434 | |
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| 435 | !----------------------------------------------------------------------- |
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| 436 | ! |
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| 437 | ! this routine stores the address and weight for this link in |
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| 438 | ! the appropriate address and weight arrays and resizes those |
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| 439 | ! arrays if necessary. |
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| 440 | ! |
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| 441 | !----------------------------------------------------------------------- |
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| 442 | |
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| 443 | !----------------------------------------------------------------------- |
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| 444 | ! |
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| 445 | ! input variables |
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| 446 | ! |
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| 447 | !----------------------------------------------------------------------- |
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| 448 | |
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| 449 | integer (kind=int_kind), intent(in) :: & |
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| 450 | add1, & ! address on grid1 |
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| 451 | add2, & ! address on grid2 |
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| 452 | nmap ! identifies which direction for mapping |
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| 453 | |
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| 454 | real (kind=dbl_kind), dimension(:), intent(in) :: & |
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| 455 | weights ! array of remapping weights for this link |
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| 456 | |
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| 457 | !----------------------------------------------------------------------- |
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| 458 | ! |
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| 459 | ! increment number of links and check to see if remap arrays need |
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| 460 | ! to be increased to accomodate the new link. then store the |
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| 461 | ! link. |
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| 462 | ! |
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| 463 | !----------------------------------------------------------------------- |
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| 464 | |
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| 465 | select case (nmap) |
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| 466 | case(1) |
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| 467 | |
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| 468 | num_links_map1 = num_links_map1 + 1 |
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| 469 | |
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| 470 | if (num_links_map1 > max_links_map1) & |
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| 471 | call resize_remap_vars(1,resize_increment) |
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| 472 | |
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| 473 | grid1_add_map1(num_links_map1) = add1 |
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| 474 | grid2_add_map1(num_links_map1) = add2 |
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| 475 | wts_map1 (:,num_links_map1) = weights |
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| 476 | |
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| 477 | case(2) |
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| 478 | |
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| 479 | num_links_map2 = num_links_map2 + 1 |
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| 480 | |
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| 481 | if (num_links_map2 > max_links_map2) & |
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| 482 | call resize_remap_vars(2,resize_increment) |
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| 483 | |
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| 484 | grid1_add_map2(num_links_map2) = add1 |
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| 485 | grid2_add_map2(num_links_map2) = add2 |
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| 486 | wts_map2 (:,num_links_map2) = weights |
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| 487 | |
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| 488 | end select |
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| 489 | |
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| 490 | !----------------------------------------------------------------------- |
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| 491 | |
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| 492 | end subroutine store_link_nbr |
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| 493 | |
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| 494 | !*********************************************************************** |
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| 495 | |
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| 496 | end module remap_distance_weight |
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| 497 | |
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| 498 | !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! |
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