1 | MODULE limmp |
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2 | !!====================================================================== |
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3 | !! *** MODULE limmp *** |
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4 | !! Melt ponds |
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5 | !!====================================================================== |
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6 | !! history : ! Original code by Daniela Flocco and Adrian Turner |
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7 | !! 1.0 ! 2012 (O. Lecomte) Adaptation for scientific tests (NEMO3.1) |
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8 | !! 2.0 ! 2017 (M. Vancoppenolle, O. Lecomte, C. Rousset) Implementation in NEMO3.6 |
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9 | !!---------------------------------------------------------------------- |
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10 | #if defined key_lim3 |
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11 | !!---------------------------------------------------------------------- |
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12 | !! 'key_lim3' : LIM3 sea-ice model |
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13 | !!---------------------------------------------------------------------- |
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14 | !! lim_mp_init : some initialization and namelist read |
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15 | !! lim_mp : main calling routine |
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16 | !!---------------------------------------------------------------------- |
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17 | USE phycst ! physical constants |
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18 | USE dom_oce ! ocean space and time domain |
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19 | USE ice ! LIM-3 variables |
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20 | ! |
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21 | USE lbclnk ! lateral boundary conditions - MPP exchanges |
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22 | USE lib_mpp ! MPP library |
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23 | USE in_out_manager ! I/O manager |
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24 | USE lib_fortran ! glob_sum |
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25 | USE timing ! Timing |
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26 | |
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27 | IMPLICIT NONE |
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28 | PRIVATE |
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29 | |
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30 | PUBLIC lim_mp_init ! routine called by icestp.F90 |
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31 | PUBLIC lim_mp ! routine called by icestp.F90 |
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32 | |
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33 | INTEGER :: nice_pnd ! choice of the type of pond scheme |
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34 | ! ! associated indices: |
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35 | INTEGER, PARAMETER :: np_pndNO = 0 ! No pond scheme |
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36 | INTEGER, PARAMETER :: np_pndCST = 1 ! Constant pond scheme |
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37 | INTEGER, PARAMETER :: np_pndH12 = 2 ! Evolutive pond scheme (Holland et al. 2012) |
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38 | |
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39 | !! * Substitutions |
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40 | # include "vectopt_loop_substitute.h90" |
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41 | !!---------------------------------------------------------------------- |
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42 | !! NEMO/LIM3 4.0 , UCL - NEMO Consortium (2011) |
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43 | !! $Id: limdyn.F90 6994 2016-10-05 13:07:10Z clem $ |
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44 | !! Software governed by the CeCILL licence (NEMOGCM/NEMO_CeCILL.txt) |
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45 | !!---------------------------------------------------------------------- |
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46 | CONTAINS |
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47 | |
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48 | SUBROUTINE lim_mp( kt ) |
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49 | !!------------------------------------------------------------------- |
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50 | !! *** ROUTINE lim_mp *** |
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51 | !! |
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52 | !! ** Purpose : change melt pond fraction |
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53 | !! |
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54 | !! ** Method : brutal force |
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55 | !! |
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56 | !! ** Action : - |
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57 | !! - |
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58 | !!------------------------------------------------------------------------------------ |
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59 | INTEGER, INTENT(in) :: kt ! number of iteration |
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60 | INTEGER :: ji, jj, jl ! dummy loop indices |
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61 | !!------------------------------------------------------------------- |
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62 | |
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63 | IF( nn_timing == 1 ) CALL timing_start('lim_mp') |
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64 | |
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65 | SELECT CASE ( nice_pnd ) |
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66 | |
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67 | CASE (np_pndCST) |
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68 | ! !------------------------------! |
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69 | CALL lim_mp_CST ! Constant melt ponds ! |
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70 | ! !------------------------------! |
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71 | CASE (np_pndH12) |
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72 | ! !------------------------------! |
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73 | CALL lim_mp_H12 ! Holland et al 2012 melt ponds! |
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74 | ! !------------------------------! |
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75 | END SELECT |
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76 | |
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77 | IF( nn_timing == 1 ) CALL timing_stop('lim_mp') |
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78 | |
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79 | END SUBROUTINE lim_mp |
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80 | |
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81 | SUBROUTINE lim_mp_CST |
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82 | !!------------------------------------------------------------------- |
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83 | !! *** ROUTINE lim_mp_CST *** |
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84 | !! |
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85 | !! ** Purpose : Compute melt pond evolution |
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86 | !! |
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87 | !! ** Method : Melt pond fraction and thickness are prescribed |
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88 | !! to non-zero values when t_su = 0C |
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89 | !! |
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90 | !! ** Tunable parameters : pond fraction (rn_apnd), pond depth (rn_hpnd) |
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91 | !! |
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92 | !! ** Note : Coupling with such melt ponds is only radiative |
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93 | !! Advection, ridging, rafting... are bypassed |
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94 | !! |
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95 | !! ** References : Bush, G.W., and Trump, D.J. (2017) |
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96 | !! |
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97 | !!------------------------------------------------------------------- |
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98 | |
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99 | WHERE ( ( a_i > epsi10 ) .AND. ( t_su >= rt0-epsi06 ) ) |
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100 | !! WHERE ( ( a_i > 0._wp ) .AND. ( t_su >= rt0 ) ) |
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101 | a_ip_frac = rn_apnd |
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102 | h_ip = rn_hpnd |
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103 | v_ip = a_ip_frac * a_i * h_ip |
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104 | a_ip = a_ip_frac * a_i |
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105 | ELSE WHERE |
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106 | a_ip = 0._wp |
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107 | h_ip = 0._wp |
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108 | v_ip = 0._wp |
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109 | a_ip_frac = 0._wp |
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110 | END WHERE |
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111 | |
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112 | wfx_pnd(:,:) = 0._wp |
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113 | |
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114 | END SUBROUTINE lim_mp_CST |
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115 | |
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116 | SUBROUTINE lim_mp_H12 |
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117 | !!------------------------------------------------------------------- |
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118 | !! *** ROUTINE lim_mp_H12 *** |
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119 | !! |
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120 | !! ** Purpose : Compute melt pond evolution |
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121 | !! |
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122 | !! ** Method : Empirical method. A fraction of meltwater is accumulated |
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123 | !! in pond volume. It is then released exponentially when |
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124 | !! surface is freezing. |
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125 | !! |
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126 | !! ** Tunable parameters : (no real expertise yet, ideas?) |
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127 | !! |
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128 | !! ** Note : Stolen from CICE for quick test of the melt pond |
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129 | !! radiation and freshwater interfaces |
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130 | !! Coupling can be radiative AND freshwater |
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131 | !! Advection, ridging, rafting are called |
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132 | !! |
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133 | !! ** References : Holland, M. M. et al (J Clim 2012) |
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134 | !! |
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135 | !!------------------------------------------------------------------- |
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136 | |
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137 | INTEGER, DIMENSION(jpij) :: indxi ! compressed indices for cells with ice melting |
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138 | INTEGER, DIMENSION(jpij) :: indxj ! |
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139 | |
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140 | REAL(wp), DIMENSION(jpi,jpj) :: zwfx_mlw ! available meltwater for melt ponding |
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141 | REAL(wp), DIMENSION(jpi,jpj,jpl) :: zrfrac ! fraction of available meltwater retained for melt ponding |
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142 | |
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143 | REAL(wp), PARAMETER :: zrmin = 0.15_wp ! minimum fraction of available meltwater retained for melt ponding |
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144 | REAL(wp), PARAMETER :: zrmax = 0.70_wp ! maximum '' '' '' '' '' |
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145 | REAL(wp), PARAMETER :: zrexp = 0.01_wp ! rate constant to refreeze melt ponds |
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146 | REAL(wp), PARAMETER :: zpnd_aspect = 0.8_wp ! pond aspect ratio |
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147 | |
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148 | REAL(wp) :: zhi ! dummy ice thickness |
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149 | REAL(wp) :: zhs ! dummy snow depth |
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150 | REAL(wp) :: zTp ! reference temperature |
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151 | REAL(wp) :: zdTs ! dummy temperature difference |
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152 | REAL(wp) :: z1_rhofw ! inverse freshwater density |
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153 | REAL(wp) :: z1_zpnd_aspect ! inverse pond aspect ratio |
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154 | REAL(wp) :: zvpold ! dummy pond volume |
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155 | |
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156 | INTEGER :: ji, jj, jl, ij ! loop indices |
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157 | INTEGER :: icells ! size of dummy array |
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158 | !!------------------------------------------------------------------- |
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159 | z1_rhofw = 1. / rhofw |
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160 | z1_zpnd_aspect = 1. / zpnd_aspect |
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161 | zTp = -2. |
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162 | |
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163 | a_ip_frac(:,:,:) = 0._wp |
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164 | h_ip (:,:,:) = 0._wp |
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165 | |
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166 | !------------------------------------------------------------------ |
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167 | ! Available melt water for melt ponding and corresponding fraction |
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168 | !------------------------------------------------------------------ |
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169 | |
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170 | zwfx_mlw(:,:) = MAX( wfx_sum(:,:) + wfx_snw_sum(:,:), 0._wp ) ! available meltwater for melt ponding |
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171 | |
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172 | ! NB: zwfx_mlw can be slightly negative for very small values (why?) |
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173 | ! This can in some occasions give negative |
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174 | ! v_ip in the first category, which then gives crazy pond |
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175 | ! fractions and crashes the code as soon as the melt-pond |
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176 | ! radiative coupling is activated |
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177 | ! if we understand and remove why wfx_sum or wfx_snw could be |
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178 | ! negative, then, we can remove the MAX |
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179 | ! NB: I now changed to wfx_snw_sum, this may fix the problem. |
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180 | ! We should check |
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181 | |
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182 | zrfrac(:,:,:) = zrmin + ( zrmax - zrmin ) * a_i(:,:,:) |
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183 | |
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184 | DO jl = 1, jpl |
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185 | |
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186 | !------------------------------------------------------------------------------ |
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187 | ! Identify grid cells where ponds should be updated (can probably be improved) |
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188 | !------------------------------------------------------------------------------ |
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189 | indxi(:) = 0 |
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190 | indxj(:) = 0 |
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191 | icells = 0 |
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192 | DO jj = 1, jpj |
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193 | DO ji = 1, jpi |
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194 | IF ( a_i(ji,jj,jl) > epsi10 ) THEN |
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195 | icells = icells + 1 |
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196 | indxi(icells) = ji |
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197 | indxj(icells) = jj |
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198 | ENDIF |
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199 | END DO |
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200 | END DO |
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201 | |
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202 | DO ij = 1, icells |
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203 | |
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204 | ji = indxi(ij) |
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205 | jj = indxj(ij) |
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206 | |
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207 | zhi = v_i(ji,jj,jl) / a_i(ji,jj,jl) |
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208 | zhs = v_s(ji,jj,jl) / a_i(ji,jj,jl) |
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209 | |
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210 | IF ( zhi < rn_himin) THEN !--- Remove ponds on thin ice if ice is too thin |
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211 | |
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212 | a_ip(ji,jj,jl) = 0._wp !--- Dump ponds |
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213 | v_ip(ji,jj,jl) = 0._wp |
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214 | a_ip_frac(ji,jj,jl) = 0._wp |
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215 | h_ip(ji,jj,jl) = 0._wp |
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216 | |
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217 | IF ( ln_pnd_fwb ) & !--- Give freshwater to the ocean |
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218 | wfx_pnd(ji,jj) = wfx_pnd(ji,jj) + v_ip(ji,jj,jl) |
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219 | |
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220 | |
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221 | ELSE !--- Update pond characteristics |
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222 | |
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223 | !--- Add retained melt water to melt ponds |
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224 | ! v_ip should never be positive, otherwise code crashes |
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225 | ! MV: as far as I saw, UM5 can create very small negative v_ip values |
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226 | ! hence I added the max, which was not required with Prather (1 yr run) |
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227 | v_ip(ji,jj,jl) = MAX( v_ip(ji,jj,jl), 0._wp ) + zrfrac(ji,jj,jl) * z1_rhofw * zwfx_mlw(ji,jj) * a_i(ji,jj,jl) * rdt_ice |
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228 | |
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229 | !--- Shrink pond due to refreezing |
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230 | zdTs = MAX ( zTp - t_su(ji,jj,jl) + rt0 , 0. ) |
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231 | |
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232 | zvpold = v_ip(ji,jj,jl) |
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233 | |
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234 | v_ip(ji,jj,jl) = v_ip(ji,jj,jl) * EXP( zrexp * zdTs / zTp ) |
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235 | |
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236 | !--- Dump meltwater due to refreezing ( of course this is wrong |
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237 | !--- but this parameterization is too simple ) |
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238 | IF ( ln_pnd_fwb ) & |
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239 | wfx_pnd(ji,jj) = wfx_pnd(ji,jj) + rhofw * ( v_ip(ji,jj,jl) - zvpold ) * r1_rdtice |
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240 | |
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241 | a_ip_frac(ji,jj,jl) = MIN( 1._wp , SQRT( v_ip(ji,jj,jl) * z1_zpnd_aspect / a_i(ji,jj,jl) ) ) |
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242 | !NB: the SQRT has been a recurring source of crash when v_ip or a_i tuns to be even only slightly negative |
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243 | |
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244 | h_ip(ji,jj,jl) = zpnd_aspect * a_ip_frac(ji,jj,jl) |
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245 | |
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246 | a_ip(ji,jj,jl) = a_ip_frac(ji,jj,jl) * a_i(ji,jj,jl) |
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247 | |
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248 | ENDIF |
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249 | |
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250 | END DO |
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251 | |
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252 | END DO ! jpl |
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253 | |
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254 | !--- Remove retained meltwater from surface fluxes |
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255 | |
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256 | IF ( ln_pnd_fwb ) THEN |
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257 | |
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258 | wfx_snw_sum(:,:) = wfx_snw_sum(:,:) * ( 1. - zrmin - ( zrmax - zrmin ) * SUM( a_i(:,:,:), dim=3 ) ) |
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259 | wfx_sum(:,:) = wfx_sum(:,:) * ( 1. - zrmin - ( zrmax - zrmin ) * SUM( a_i(:,:,:), dim=3 ) ) |
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260 | |
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261 | ENDIF |
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262 | |
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263 | END SUBROUTINE lim_mp_H12 |
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264 | |
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265 | SUBROUTINE lim_mp_init |
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266 | !!------------------------------------------------------------------- |
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267 | !! *** ROUTINE lim_mp_init *** |
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268 | !! |
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269 | !! ** Purpose : Physical constants and parameters linked to melt ponds |
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270 | !! over sea ice |
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271 | !! |
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272 | !! ** Method : Read the nammp namelist and check the melt pond |
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273 | !! parameter values called at the first timestep (nit000) |
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274 | !! |
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275 | !! ** input : Namelist nammp |
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276 | !!------------------------------------------------------------------- |
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277 | INTEGER :: ios, ioptio ! Local integer output status for namelist read |
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278 | NAMELIST/nammp/ ln_pnd_H12, ln_pnd_fwb, ln_pnd_CST, rn_apnd, rn_hpnd, ln_pnd_alb |
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279 | !!------------------------------------------------------------------- |
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280 | |
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281 | REWIND( numnam_ice_ref ) ! Namelist nammp in reference namelist : Melt Ponds |
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282 | READ ( numnam_ice_ref, nammp, IOSTAT = ios, ERR = 901) |
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283 | 901 IF( ios /= 0 ) CALL ctl_nam ( ios , 'nammp in reference namelist', lwp ) |
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284 | |
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285 | REWIND( numnam_ice_cfg ) ! Namelist nammp in configuration namelist : Melt Ponds |
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286 | READ ( numnam_ice_cfg, nammp, IOSTAT = ios, ERR = 902 ) |
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287 | 902 IF( ios /= 0 ) CALL ctl_nam ( ios , 'nammp in configuration namelist', lwp ) |
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288 | IF(lwm) WRITE ( numoni, nammp ) |
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289 | |
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290 | IF(lwp) THEN ! control print |
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291 | WRITE(numout,*) |
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292 | WRITE(numout,*) 'ice_thd_pnd_init: ice parameters for melt ponds' |
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293 | WRITE(numout,*) '~~~~~~~~~~~~~~~~' |
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294 | WRITE(numout,*) ' Namelist namicethd_pnd:' |
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295 | WRITE(numout,*) ' Evolutive melt pond fraction and depth (Holland et al 2012) ln_pnd_H12 = ', ln_pnd_H12 |
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296 | WRITE(numout,*) ' Melt ponds store fresh water or not ln_pnd_fwb = ', ln_pnd_fwb |
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297 | WRITE(numout,*) ' Prescribed melt pond fraction and depth ln_pnd_Cst = ', ln_pnd_CST |
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298 | WRITE(numout,*) ' Prescribed pond fraction rn_apnd = ', rn_apnd |
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299 | WRITE(numout,*) ' Prescribed pond depth rn_hpnd = ', rn_hpnd |
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300 | WRITE(numout,*) ' Melt ponds affect albedo or not ln_pnd_alb = ', ln_pnd_alb |
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301 | ENDIF |
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302 | ! |
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303 | ! !== set the choice of ice pond scheme ==! |
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304 | ioptio = 0 |
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305 | nice_pnd = np_pndNO |
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306 | IF( ln_pnd_CST ) THEN ; ioptio = ioptio + 1 ; nice_pnd = np_pndCST ; ENDIF |
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307 | IF( ln_pnd_H12 ) THEN ; ioptio = ioptio + 1 ; nice_pnd = np_pndH12 ; ENDIF |
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308 | IF( ioptio > 1 ) CALL ctl_stop( 'ice_thd_pnd_init: choose one and only one pond scheme (ln_pnd_H12 or ln_pnd_CST)' ) |
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309 | |
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310 | SELECT CASE( nice_pnd ) |
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311 | CASE( np_pndNO ) |
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312 | IF(ln_pnd_fwb) THEN ; ln_pnd_fwb = .FALSE. ; CALL ctl_warn( 'ln_pnd_fwb=false when no ponds' ) ; ENDIF |
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313 | IF(ln_pnd_alb) THEN ; ln_pnd_alb = .FALSE. ; CALL ctl_warn( 'ln_pnd_alb=false when no ponds' ) ; ENDIF |
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314 | CASE( np_pndCST) |
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315 | IF(ln_pnd_fwb) THEN ; ln_pnd_fwb = .FALSE. ; CALL ctl_warn( 'ln_pnd_fwb=false when ln_pnd_CST=true' ) ; ENDIF |
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316 | END SELECT |
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317 | ! |
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318 | END SUBROUTINE lim_mp_init |
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319 | |
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320 | #else |
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321 | !!---------------------------------------------------------------------- |
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322 | !! Default option Empty module NO ESIM sea-ice model |
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323 | !!---------------------------------------------------------------------- |
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324 | #endif |
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325 | |
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326 | !!====================================================================== |
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327 | END MODULE limmp |
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