1 | SUBROUTINE gradient_conserv(NX1, NY1, src_array, sou_mask, & |
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2 | src_latitudes, src_longitudes, & |
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3 | id_per, cd_per, & |
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4 | grad_lat, grad_lon) |
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5 | |
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6 | !**** |
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7 | ! ***************************** |
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8 | ! * OASIS ROUTINE - LEVEL ? * |
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9 | ! * ------------- ------- * |
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10 | ! ***************************** |
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11 | ! |
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12 | !**** *gradient_conserv* - calculate gradients for conservative remapping |
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13 | ! |
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14 | ! Purpose: |
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15 | ! ------- |
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16 | ! Calculation of gradients in latitudinal and longitudinal direction. |
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17 | ! In a first step the gradients in direction of source-grid rows |
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18 | ! and lines are calculated. Then they are rotated to longitudinal |
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19 | ! and latitudinal direction, using the scalar product. |
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20 | ! This routine works for logically rectangular grids, only. |
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21 | ! |
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22 | !** Interface: |
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23 | ! --------- |
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24 | ! *CALL* *gradient_conserv*(NX1, NY1, src_array, sou_mask, src_latitudes, & |
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25 | ! src_longitudes, grad_lat, grad_lon) |
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26 | ! |
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27 | ! Input: |
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28 | ! ----- |
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29 | ! NX1 : grid dimension in x-direction (integer) |
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30 | ! NY1 : grid dimension in y-direction (integer) |
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31 | ! src_array : array on source grid (real 2D) |
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32 | ! sou_mask : source grid mask (integer 2D) |
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33 | ! src_latitudes : latitudes on source grid (real 2D) |
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34 | ! src_longitudes : longitudes on source grid (real 2D) |
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35 | ! id_per : number of overlapping points for source grid |
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36 | ! cd_per : grip periodicity type |
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37 | ! |
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38 | ! Output: |
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39 | ! ------ |
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40 | ! grad_lat : gradient in latitudinal direction (real 2D) |
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41 | ! grad_lon : gradient in longitudinal direction (real 2D) |
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42 | ! |
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43 | ! History: |
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44 | ! ------- |
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45 | ! Version Programmer Date Description |
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46 | ! ------- ---------- ---- ----------- |
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47 | ! 2.5 V. Gayler 2001/09/20 created |
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48 | ! |
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49 | ! %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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50 | |
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51 | IMPLICIT NONE |
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52 | |
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53 | INTEGER, PARAMETER :: wp = SELECTED_REAL_KIND(12,307) ! double |
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54 | !----------------------------------------------------------------------- |
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55 | ! INTENT(IN) |
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56 | !----------------------------------------------------------------------- |
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57 | INTEGER, INTENT(IN) :: & |
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58 | NX1, NY1, & ! source grid dimensions |
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59 | id_per ! nbr of overlapping grid points |
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60 | |
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61 | CHARACTER*8, INTENT(IN) :: & |
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62 | cd_per ! grip periodicity type |
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63 | |
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64 | REAL (kind=wp), DIMENSION(NX1,NY1), INTENT(IN) :: & |
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65 | src_array ! array on source grid |
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66 | |
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67 | INTEGER, DIMENSION(NX1,NY1), INTENT(IN) :: & |
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68 | sou_mask ! source grid mask |
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69 | |
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70 | REAL (kind=wp), DIMENSION(NX1,NY1), INTENT(IN) :: & |
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71 | src_latitudes, & ! source grid latitudes |
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72 | src_longitudes ! source grid longitudes |
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73 | |
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74 | !----------------------------------------------------------------------- |
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75 | ! INTENT(OUT) |
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76 | !----------------------------------------------------------------------- |
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77 | REAL (kind=wp), DIMENSION(NX1,NY1), INTENT(OUT) :: & |
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78 | grad_lat, & ! gradient in latitudinal direction |
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79 | grad_lon ! gradient in longitudinal direction |
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80 | |
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81 | !----------------------------------------------------------------------- |
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82 | ! LOCAL VARIABLES |
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83 | !----------------------------------------------------------------------- |
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84 | INTEGER :: & |
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85 | i, j, & ! looping indicees |
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86 | ip1, jp1, im1, jm1 |
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87 | |
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88 | REAL (kind=wp) :: & |
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89 | distance_rad ! distance in rad |
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90 | |
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91 | REAL (kind=wp) :: & |
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92 | dVar_i, dVar_j, & ! difference of Var in i / j direction |
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93 | dlat_i, dlat_j, & ! difference in lat in i / j direction |
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94 | dlon_i, dlon_j, & ! difference in lon in i / j direction |
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95 | dist_i, dist_j, & ! distance in i / j direction |
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96 | grad_i, grad_j, & ! gradient in i / j direction |
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97 | ABSold, ABSnew, lat_factor |
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98 | |
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99 | REAL (kind=wp), DIMENSION(NX1,NY1) :: & |
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100 | src_lon, & ! source grid longitudes [radiants] |
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101 | src_lat, & ! source grid latitudes [radiants] |
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102 | pi180 ! conversion factor: deg -> rad |
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103 | REAL (kind=wp), PARAMETER :: & |
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104 | pi = 3.14159265358979323846, & ! PI |
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105 | pi2 = 2.0d0*pi ! 2PI |
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106 | |
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107 | INTEGER, PARAMETER :: il_maskval= 1 ! in our grids sea_value = 0 and land_value = 1 |
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108 | |
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109 | !----------------------------------------------------------------------- |
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110 | ! |
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111 | !! IF (nlogprt .GE. 2) THEN |
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112 | !! WRITE (UNIT = nulou,FMT = *)' ' |
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113 | !! WRITE (UNIT = nulou,FMT = *)' Entering routine gradient_conserv ' |
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114 | !! WRITE (UNIT = nulou,FMT = *)' ' |
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115 | !! CALL FLUSH(nulou) |
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116 | !! ENDIF |
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117 | ! |
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118 | ! Transformation from degree to radiant |
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119 | ! ------------------------------------- |
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120 | pi180 = 1.74532925199432957692e-2 ! =PI/180 |
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121 | |
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122 | src_lon = src_longitudes * pi180 |
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123 | src_lat = src_latitudes * pi180 |
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124 | |
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125 | !----------------------------------------------------------------------- |
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126 | |
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127 | DO i = 1, NX1 |
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128 | |
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129 | DO j = 1, NY1 |
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130 | |
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131 | IF (sou_mask(i,j) /= il_maskval) THEN |
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132 | |
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133 | ip1 = i + 1 |
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134 | im1 = i - 1 |
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135 | IF (i == NX1) THEN |
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136 | IF (cd_per == 'P') ip1 = 1 + id_per ! the 0-meridian |
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137 | IF (cd_per == 'R') ip1 = NX1 |
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138 | ENDIF |
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139 | IF (i == 1 ) THEN |
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140 | IF (cd_per == 'P') im1 = NX1 - id_per |
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141 | IF (cd_per == 'R') im1 = 1 |
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142 | ENDIF |
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143 | jp1 = j + 1 |
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144 | jm1 = j - 1 |
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145 | IF (j == NY1) jp1 = NY1 ! treatment of the last.. |
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146 | IF (j == 1 ) jm1 = 1 ! .. and the first grid-row |
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147 | |
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148 | IF (sou_mask(ip1,j) == il_maskval) ip1 = i |
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149 | IF (sou_mask(im1,j) == il_maskval) im1 = i |
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150 | IF (sou_mask(i,jp1) == il_maskval) jp1 = j |
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151 | IF (sou_mask(i,jm1) == il_maskval) jm1 = j |
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152 | |
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153 | ! difference between neighbouring datapoints |
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154 | dVar_i = src_array(ip1,j) - src_array(im1,j) |
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155 | dVar_j = src_array(i,jp1) - src_array(i,jm1) |
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156 | |
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157 | ! difference in latitudes |
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158 | dlat_i = src_lat(ip1,j) - src_lat(im1,j) |
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159 | dlat_j = src_lat(i,jp1) - src_lat(i,jm1) |
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160 | |
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161 | ! difference in longitudes |
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162 | dlon_i = src_lon(ip1,j) - src_lon(im1,j) |
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163 | IF (dlon_i > pi) dlon_i = dlon_i - pi2 |
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164 | IF (dlon_i < (-pi)) dlon_i = dlon_i + pi2 |
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165 | dlon_j = src_lon(i,jp1) - src_lon(i,jm1) |
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166 | IF (dlon_j > pi) dlon_j = dlon_j - pi2 |
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167 | IF (dlon_j < (-pi)) dlon_j = dlon_j + pi2 |
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168 | lat_factor = COS(src_lat(i,j)) |
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169 | dlon_i = dlon_i * lat_factor |
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170 | dlon_j = dlon_j * lat_factor |
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171 | |
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172 | ! distance |
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173 | dist_i = distance_rad(src_lon(ip1,j), src_lat(ip1,j), & |
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174 | src_lon(im1,j), src_lat(im1,j)) |
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175 | dist_j = distance_rad(src_lon(i,jp1), src_lat(i,jp1), & |
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176 | src_lon(i,jm1), src_lat(i,jm1)) |
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177 | |
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178 | ! gradients: dVar / distance (= vector lenght) |
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179 | IF (dist_i /= 0.) THEN |
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180 | grad_i = dVar_i / dist_i |
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181 | ELSE |
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182 | grad_i = 0 |
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183 | ENDIF |
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184 | IF (dist_j /= 0.) THEN |
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185 | grad_j = dVar_j / dist_j |
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186 | ELSE |
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187 | grad_j = 0 |
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188 | ENDIF |
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189 | |
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190 | ! projection by scalar product |
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191 | ! ---------------------------- |
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192 | grad_lon(i,j) = grad_i * dlon_i + grad_j * dlat_i |
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193 | grad_lat(i,j) = grad_i * dlon_j + grad_j * dlat_j |
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194 | |
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195 | IF (dist_i /= 0) then |
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196 | grad_lon(i,j) = grad_lon(i,j) / dist_i |
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197 | ELSE |
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198 | grad_lon(i,j) = 0 |
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199 | ENDIF |
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200 | IF (dist_j /= 0) then |
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201 | grad_lat(i,j) = grad_lat(i,j) / dist_j |
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202 | ELSE |
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203 | grad_lat(i,j) = 0. |
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204 | ENDIF |
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205 | |
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206 | ! correct skale |
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207 | ! ------------- |
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208 | ABSold = SQRT(grad_i**2 + grad_j**2) |
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209 | ABSnew = SQRT(grad_lon(i,j)**2 + grad_lat(i,j)**2) |
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210 | IF (ABSnew > 1.E-10) THEN |
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211 | ! grad_lon(i,j) = grad_lon(i,j)*ABSold/ABSnew |
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212 | grad_lon(i,j) = grad_lon(i,j) |
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213 | ELSE |
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214 | grad_lon(i,j) = 0.0 |
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215 | ENDIF |
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216 | |
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217 | ! test orthogonality |
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218 | ! ------------------ |
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219 | IF ((dlon_i*dlon_j+dlat_j*dlat_i) > 0.1) THEN |
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220 | print*, 'ORTHOGONAL? ', i, j, (dlon_i*dlon_j+dlat_j*dlat_i) |
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221 | ENDIF |
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222 | |
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223 | ELSE |
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224 | |
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225 | grad_lat(i,j) = 0. |
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226 | grad_lon(i,j) = 0. |
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227 | |
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228 | ENDIF |
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229 | |
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230 | ENDDO |
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231 | ENDDO |
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232 | !! IF (nlogprt .GE. 2) THEN |
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233 | !! WRITE (UNIT = nulou,FMT = *)' ' |
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234 | !! WRITE (UNIT = nulou,FMT = *)' Leaving routine gradient ' |
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235 | !! WRITE (UNIT = nulou,FMT = *)' ' |
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236 | !! CALL FLUSH(nulou) |
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237 | !! ENDIF |
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238 | |
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239 | END SUBROUTINE gradient_conserv |
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