1 | MODULE limthd_lac_2 |
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2 | !!====================================================================== |
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3 | !! *** MODULE limthd_lac_2 *** |
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4 | !! LIM 2 ice model : thermodynamics -- lateral accretion of the ice |
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5 | !!====================================================================== |
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6 | !! History : LIM ! 2001-04 (UCL) original code |
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7 | !! 2.0 ! 2002-08 (C. Ethe, G. Madec) F90, mpp |
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8 | !!---------------------------------------------------------------------- |
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9 | #if defined key_lim2 |
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10 | !!---------------------------------------------------------------------- |
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11 | !! 'key_lim2' : LIM 2.0 sea-ice model |
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12 | !!---------------------------------------------------------------------- |
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13 | !! lim_lat_acr_2 : lateral accretion of ice |
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14 | !!---------------------------------------------------------------------- |
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15 | USE par_oce ! ocean parameters |
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16 | USE phycst ! physical constants |
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17 | USE ice_2 ! LIM 2 sea-ice variables |
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18 | USE limistate_2 ! LIM 2 initial state |
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19 | |
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20 | IMPLICIT NONE |
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21 | PRIVATE |
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22 | |
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23 | PUBLIC lim_thd_lac_2 ! called by lim_thd_2 |
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24 | |
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25 | REAL(wp) :: epsi20 = 1.e-20 ! constant values |
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26 | REAL(wp) :: epsi13 = 1.e-13 ! |
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27 | REAL(wp) :: rzero = 0.e0 ! |
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28 | REAL(wp) :: rone = 1.e0 ! |
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29 | |
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30 | !!---------------------------------------------------------------------- |
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31 | !! NEMO/LIM 3.3, UCL-LOCEAN-IPSL (2010) |
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32 | !! $Id$ |
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33 | !! Software governed by the CeCILL licence (modipsl/doc/NEMO_CeCILL.txt) |
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34 | !!---------------------------------------------------------------------- |
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35 | CONTAINS |
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36 | |
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37 | SUBROUTINE lim_thd_lac_2( kideb, kiut ) |
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38 | !!------------------------------------------------------------------- |
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39 | !! *** ROUTINE lim_thd_lac_2 *** |
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40 | !! |
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41 | !! ** Purpose : Computation of the evolution of the ice thickness and |
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42 | !! concentration as a function of the heat balance in the leads. |
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43 | !! It is only used for lateral accretion |
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44 | !! |
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45 | !! ** Method : Ice is formed in the open water when ocean lose heat |
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46 | !! (heat budget of open water Bl is negative) . |
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47 | !! Computation of the increase of 1-A (ice concentration) fol- |
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48 | !! lowing the law : |
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49 | !! (dA/dt)acc = F[ (1-A)/(1-a) ] * [ Bl / (Li*h0) ] |
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50 | !! where - h0 is the thickness of ice created in the lead |
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51 | !! - a is a minimum fraction for leads |
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52 | !! - F is a monotonic non-increasing function defined as: |
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53 | !! F(X)=( 1 - X**exld )**(1.0/exld) |
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54 | !! - exld is the exponent closure rate (=2 default val.) |
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55 | !! |
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56 | !! ** Action : - Adjustment of snow and ice thicknesses and heat |
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57 | !! content in brine pockets |
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58 | !! - Updating ice internal temperature |
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59 | !! - Computation of variation of ice volume and mass |
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60 | !! - Computation of frldb after lateral accretion and |
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61 | !! update h_snow_1d, h_ice_1d and tbif_1d(:,:) |
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62 | !! |
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63 | !! References : M. Maqueda, 1995, PhD Thesis, Univesidad Complutense Madrid |
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64 | !! Fichefet T. and M. Maqueda 1997, J. Geo. Res., 102(C6), 12609 -12646 |
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65 | !!------------------------------------------------------------------- |
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66 | INTEGER, INTENT(in) :: kideb ! start point on which the the computation is applied |
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67 | INTEGER, INTENT(in) :: kiut ! end point on which the the computation is applied |
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68 | !! |
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69 | INTEGER :: ji ! dummy loop indices |
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70 | INTEGER :: iicefr ! 1 = existing ice ; 0 = no ice |
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71 | INTEGER :: iiceform ! 1 = ice formed ; 0 = no ice formed |
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72 | INTEGER :: ihemis ! hemisphere indicator |
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73 | REAL(wp), DIMENSION(jpij) :: zqbgow ! heat budget of the open water (negative) |
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74 | REAL(wp), DIMENSION(jpij) :: zfrl_old ! previous sea/ice fraction |
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75 | REAL(wp), DIMENSION(jpij) :: zhice_old ! previous ice thickness |
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76 | REAL(wp), DIMENSION(jpij) :: zhice0 ! thickness of newly formed ice in leads |
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77 | REAL(wp), DIMENSION(jpij) :: zfrlmin ! minimum fraction for leads |
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78 | REAL(wp), DIMENSION(jpij) :: zdhicbot ! part of thickness of newly formed ice in leads which |
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79 | ! ! has been already used in transport for example |
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80 | REAL(wp) :: zhemis ! hemisphere (0 = North, 1 = South) |
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81 | REAL(wp) :: zhicenew ! new ice thickness |
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82 | REAL(wp) :: zholds2 ! ratio of previous ice thickness and 2 |
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83 | REAL(wp) :: zhnews2 ! ratio of new ice thickness and 2 |
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84 | REAL(wp) :: zfrlnew ! new sea/ice fraction |
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85 | REAL(wp) :: zfrld ! ratio of sea/ice fraction and minimum fraction for leads |
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86 | REAL(wp) :: zfrrate ! leads-closure rate |
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87 | REAL(wp) :: zdfrl ! sea-ice fraction increment |
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88 | REAL(wp) :: zdh1 , zdh2, zdh3, zdh4, zdh5 ! tempory scalars |
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89 | REAL(wp) :: ztint, zta1, zta2, zta3, zta4 ! - - |
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90 | REAL(wp) :: zah, zalpha, zbeta ! - - |
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91 | !!--------------------------------------------------------------------- |
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92 | |
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93 | !-------------------------------------------------------------- |
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94 | ! Computation of the heat budget of the open water (negative) |
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95 | !-------------------------------------------------------------- |
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96 | DO ji = kideb , kiut |
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97 | zqbgow(ji) = qldif_1d(ji) - qcmif_1d(ji) |
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98 | END DO |
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99 | |
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100 | !----------------------------------------------------------------- |
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101 | ! Taking the appropriate values for the corresponding hemisphere |
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102 | !----------------------------------------------------------------- |
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103 | DO ji = kideb , kiut |
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104 | zhemis = MAX( zzero , SIGN( zone , frld_1d(ji) - 2.0 ) ) |
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105 | ihemis = INT( 1 + zhemis ) |
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106 | zhice0 (ji) = hiccrit( ihemis ) |
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107 | zfrlmin (ji) = acrit ( ihemis ) |
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108 | frld_1d (ji) = frld_1d(ji) - 2.0 * zhemis |
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109 | zfrl_old(ji) = frld_1d(ji) |
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110 | END DO |
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111 | |
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112 | !------------------------------------------------------------------- |
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113 | ! Lateral Accretion (modification of the fraction of open water) |
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114 | ! The ice formed in the leads has always a thickness zhice0, but |
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115 | ! only a fraction zfrrate of the ice formed contributes to the |
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116 | ! increase of the ice fraction. The remaining part (1-zfrrate) |
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117 | ! is rather assumed to lead to an increase in the thickness of the |
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118 | ! pre-existing ice (transport for example). |
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119 | ! Morales Maqueda, 1995 - Fichefet and Morales Maqueda, 1997 |
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120 | !--------------------------------------------------------------------- |
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121 | !CDIR NOVERRCHK |
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122 | DO ji = kideb , kiut |
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123 | iicefr = 1 - MAX( 0, INT( SIGN( 1.5 * zone , zfrl_old(ji) - 1.0 + epsi13 ) ) ) |
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124 | !---computation of the leads-closure rate |
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125 | zfrld = MIN( zone , ( 1.0 - frld_1d(ji) ) / ( 1.0 - zfrlmin(ji) ) ) |
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126 | zfrrate = ( 1.0 - zfrld**exld )**( 1.0 / exld ) |
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127 | !--computation of the sea-ice fraction increment and the new fraction |
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128 | zdfrl = ( zfrrate / zhice0(ji) ) * ( zqbgow(ji) / xlic ) |
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129 | zfrlnew = zfrl_old(ji) + zdfrl |
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130 | !--update the sea-ice fraction |
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131 | frld_1d (ji) = MAX( zfrlnew , zfrlmin(ji) ) |
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132 | !--computation of the remaining part of ice thickness which has been already used |
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133 | zdhicbot(ji) = ( frld_1d(ji) - zfrlnew ) * zhice0(ji) / ( 1.0 - zfrlmin(ji) ) & |
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134 | & - ( ( 1.0 - zfrrate ) / ( 1.0 - frld_1d(ji) ) ) * ( zqbgow(ji) / xlic ) |
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135 | END DO |
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136 | |
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137 | !---------------------------------------------------------------------------------------- |
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138 | ! Ajustement of snow and ice thicknesses and updating the total heat stored in brine pockets |
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139 | ! The thickness of newly formed ice is averaged with that of the pre-existing |
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140 | ! (1-Anew) * hinew = (1-Aold) * hiold + ((1-Anew)-(1-Aold)) * h0 |
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141 | ! Snow is distributed over the new ice-covered area |
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142 | ! (1-Anew) * hsnew = (1-Aold) * hsold |
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143 | !-------------------------------------------------------------------------------------------- |
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144 | DO ji = kideb , kiut |
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145 | iicefr = 1 - MAX( 0, INT( SIGN( 1.5 * zone , zfrl_old(ji) - 1.0 + epsi13 ) ) ) |
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146 | zhice_old(ji) = h_ice_1d(ji) |
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147 | zhicenew = iicefr * zhice_old(ji) + ( 1 - iicefr ) * zhice0(ji) |
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148 | zalpha = ( 1. - zfrl_old(ji) ) / ( 1.- frld_1d(ji) ) |
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149 | h_snow_1d(ji) = zalpha * h_snow_1d(ji) |
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150 | h_ice_1d (ji) = zalpha * zhicenew + ( 1.0 - zalpha ) * zhice0(ji) |
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151 | qstbif_1d(ji) = zalpha * qstbif_1d(ji) |
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152 | END DO |
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153 | |
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154 | !------------------------------------------------------- |
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155 | ! Ajustement of ice internal temperatures |
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156 | !------------------------------------------------------- |
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157 | DO ji = kideb , kiut |
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158 | iicefr = 1 - MAX( 0, INT( SIGN( 1.5 * zone , zfrl_old(ji) - 1.0 + epsi13 ) ) ) |
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159 | iiceform = 1 - MAX( 0 ,INT( SIGN( 1.5 * zone , zhice0(ji) - h_ice_1d(ji) ) ) ) |
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160 | zholds2 = zhice_old(ji)/ 2. |
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161 | zhnews2 = h_ice_1d(ji) / 2. |
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162 | zdh1 = MAX( zzero , zhice_old(ji) - zhnews2 ) |
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163 | zdh2 = MAX( zzero , -zhice_old(ji) + zhnews2 ) |
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164 | zdh3 = MAX( zzero , h_ice_1d(ji) - zholds2 ) |
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165 | zdh4 = MAX( zzero , -h_ice_1d(ji) + zholds2 ) |
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166 | zdh5 = MAX( zzero , zhice0(ji) - zholds2 ) |
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167 | ztint = iiceform * ( ( zholds2 - zdh3 ) * tbif_1d(ji,3) + zdh4 * tbif_1d(ji,2) ) & |
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168 | & / MAX( epsi20 , h_ice_1d(ji) - zhice0(ji) ) & |
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169 | & + ( 1 - iiceform ) * tfu_1d(ji) |
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170 | zta1 = iicefr * ( 1. - zfrl_old(ji) ) * tbif_1d(ji,2) |
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171 | zta2 = iicefr * ( 1. - zfrl_old(ji) ) * tbif_1d(ji,3) |
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172 | zta3 = iicefr * ( 1. - zfrl_old(ji) ) * ztint |
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173 | zta4 = ( zfrl_old(ji) - frld_1d (ji) ) * tfu_1d(ji) |
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174 | zah = ( 1. - frld_1d(ji) ) * zhnews2 |
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175 | |
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176 | tbif_1d(ji,2) = ( MIN( zhnews2 , zholds2 ) * zta1 & |
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177 | & + ( 1 - iiceform ) * ( zholds2 - zdh1 ) * zta2 & |
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178 | & + ( iiceform * ( zhnews2 - zhice0(ji) + zdh5 ) + ( 1 - iiceform ) * zdh2 ) * zta3 & |
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179 | & + MIN ( zhnews2 , zhice0(ji) ) * zta4 & |
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180 | & ) / zah |
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181 | |
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182 | tbif_1d(ji,3) = ( iiceform * ( zhnews2 - zdh3 ) * zta1 & |
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183 | & + ( iiceform * zdh3 + ( 1 - iiceform ) * zdh1 ) * zta2 & |
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184 | & + ( iiceform * ( zhnews2 - zdh5 ) + ( 1 - iiceform ) * ( zhnews2 - zdh1 ) ) * zta3 & |
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185 | & + ( iiceform * zdh5 + ( 1 - iiceform ) * zhnews2 ) * zta4 & |
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186 | & ) / zah |
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187 | !---removing the remaining part of ice formed which has been already used |
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188 | zbeta = h_ice_1d(ji) / ( h_ice_1d(ji) + zdhicbot(ji) ) |
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189 | h_ice_1d(ji) = h_ice_1d(ji) + zdhicbot(ji) |
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190 | tbif_1d (ji,2)= zbeta * tbif_1d(ji,2) + ( 1.0 - zbeta ) * tbif_1d(ji,3) |
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191 | tbif_1d (ji,3)= ( 2. * zbeta - 1.0 ) * tbif_1d(ji,3) + ( 2. * zdhicbot(ji) / h_ice_1d(ji) ) * tfu_1d(ji) |
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192 | |
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193 | END DO |
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194 | |
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195 | !------------------------------------------------------------- |
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196 | ! Computation of variation of ice volume and ice mass |
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197 | ! Vold = (1-Aold) * hiold ; Vnew = (1-Anew) * hinew |
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198 | ! dV = Vnew - Vold |
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199 | !------------------------------------------------------------- |
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200 | DO ji = kideb , kiut |
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201 | dvlbq_1d (ji) = ( 1. - frld_1d(ji) ) * h_ice_1d(ji) - ( 1. - zfrl_old(ji) ) * zhice_old(ji) |
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202 | rdmicif_1d(ji) = rdmicif_1d(ji) + rhoic * dvlbq_1d(ji) |
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203 | END DO |
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204 | ! |
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205 | END SUBROUTINE lim_thd_lac_2 |
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206 | |
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207 | #else |
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208 | !!---------------------------------------------------------------------- |
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209 | !! Default option Dummy module NO LIM 2.0 sea-ice model |
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210 | !!---------------------------------------------------------------------- |
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211 | #endif |
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212 | |
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213 | !!====================================================================== |
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214 | END MODULE limthd_lac_2 |
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