1 | MODULE limsbc |
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2 | !!====================================================================== |
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3 | !! *** MODULE limsbc *** |
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4 | !! computation of the flux at the sea ice/ocean interface |
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5 | !!====================================================================== |
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6 | !! History : 00-01 (H. Goosse) Original code |
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7 | !! 02-07 (C. Ethe, G. Madec) re-writing F90 |
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8 | !! 06-07 (G. Madec) surface module |
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9 | !!---------------------------------------------------------------------- |
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10 | #if defined key_ice_lim |
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11 | !!---------------------------------------------------------------------- |
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12 | !! 'key_ice_lim' LIM sea-ice model |
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13 | !!---------------------------------------------------------------------- |
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14 | !!---------------------------------------------------------------------- |
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15 | !! lim_sbc : flux at the ice / ocean interface |
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16 | !!---------------------------------------------------------------------- |
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17 | USE par_oce ! ocean parameters |
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18 | USE dom_oce ! ocean domain |
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19 | USE sbc_ice ! surface boundary condition |
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20 | USE sbc_oce ! surface boundary condition |
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21 | USE phycst ! physical constants |
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22 | USE ocfzpt ! surface ocean freezing point |
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23 | USE ice_oce ! sea-ice variable |
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24 | USE ice ! LIM sea-ice variables |
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25 | USE iceini ! ??? |
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26 | USE dynspg_oce ! choice of the surface pressure gradient scheme |
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27 | |
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28 | USE lbclnk ! ocean lateral boundary condition |
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29 | USE in_out_manager ! I/O manager |
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30 | USE albedo ! albedo parameters |
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31 | USE prtctl ! Print control |
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32 | |
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33 | IMPLICIT NONE |
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34 | PRIVATE |
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35 | |
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36 | PUBLIC lim_sbc ! called by lim_step |
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37 | |
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38 | REAL(wp) :: epsi16 = 1.e-16 ! constant values |
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39 | REAL(wp) :: rzero = 0.e0 |
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40 | REAL(wp) :: rone = 1.e0 |
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41 | |
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42 | !! * Substitutions |
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43 | # include "vectopt_loop_substitute.h90" |
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44 | !!---------------------------------------------------------------------- |
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45 | !! LIM 2.0, UCL-LOCEAN-IPSL (2006) |
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46 | !! $Header: $ |
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47 | !! Software governed by the CeCILL licence (modipsl/doc/NEMO_CeCILL.txt) |
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48 | !!---------------------------------------------------------------------- |
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49 | |
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50 | CONTAINS |
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51 | |
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52 | SUBROUTINE lim_sbc( kt ) |
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53 | !!------------------------------------------------------------------- |
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54 | !! *** ROUTINE lim_sbc *** |
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55 | !! |
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56 | !! ** Purpose : Update surface ocean boundary condition over areas |
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57 | !! that are at least partially covered by sea-ice |
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58 | !! |
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59 | !! ** Action : - comput. of the momentum, heat and freshwater/salt |
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60 | !! fluxes at the ice-ocean interface. |
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61 | !! - Update |
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62 | !! |
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63 | !! ** Outputs : - fsolar : solar heat flux at sea ice/ocean interface |
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64 | !! - fnsolar : non solar heat flux |
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65 | !! - fsalt : salt flux at sea ice/ocean interface |
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66 | !! - fmass : freshwater flux at sea ice/ocean interface |
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67 | !! |
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68 | !! References : Goosse, H. et al. 1996, Bul. Soc. Roy. Sc. Liege, 65, 87-90. |
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69 | !! Tartinville et al. 2001 Ocean Modelling, 3, 95-108. |
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70 | !!--------------------------------------------------------------------- |
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71 | INTEGER :: kt ! number of iteration |
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72 | !! |
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73 | INTEGER :: ji, jj ! dummy loop indices |
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74 | INTEGER :: ifvt, i1mfr, idfr ! some switches |
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75 | INTEGER :: iflt, ial, iadv, ifral, ifrdv |
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76 | REAL(wp) :: zqsr , zqns ! solar & non solar heat flux |
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77 | REAL(wp) :: zinda ! switch for testing the values of ice concentration |
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78 | REAL(wp) :: zfons ! salt exchanges at the ice/ocean interface |
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79 | REAL(wp) :: zemp ! freshwater exchanges at the ice/ocean interface |
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80 | REAL(wp) :: zfrldu, zfrldv ! lead fraction at U- & V-points |
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81 | REAL(wp) :: zutau , zvtau ! lead fraction at U- & V-points |
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82 | REAL(wp) :: zu_io , zv_io ! 2 components of the ice-ocean velocity |
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83 | #if defined key_coupled |
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84 | REAL(wp), DIMENSION(jpi,jpj) :: zalb ! albedo of ice under overcast sky |
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85 | REAL(wp), DIMENSION(jpi,jpj) :: zalcn ! albedo of ocean under overcast sky |
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86 | REAL(wp), DIMENSION(jpi,jpj) :: zalbp ! albedo of ice under clear sky |
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87 | REAL(wp), DIMENSION(jpi,jpj) :: zaldum ! albedo of ocean under clear sky |
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88 | #endif |
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89 | REAL(wp) :: zsang, zmod, zfm |
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90 | REAL(wp), DIMENSION(jpi,jpj) :: ztio_u, ztio_v ! ocean stress below sea-ice |
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91 | |
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92 | !!--------------------------------------------------------------------- |
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93 | |
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94 | IF( kt == nit000 ) THEN |
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95 | IF(lwp) WRITE(numout,*) |
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96 | IF(lwp) WRITE(numout,*) 'lim_sbc : LIM sea-ice - surface boundary condition' |
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97 | IF(lwp) WRITE(numout,*) '~~~~~~~ ' |
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98 | ENDIF |
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99 | |
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100 | !------------------------------------------! |
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101 | ! heat flux at the ocean surface ! |
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102 | !------------------------------------------! |
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103 | |
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104 | !!gm |
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105 | !!gm CAUTION |
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106 | !!gm re-verifies the non solar expression, especially over open ocen |
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107 | !!gm |
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108 | DO jj = 1, jpj |
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109 | DO ji = 1, jpi |
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110 | zinda = 1.0 - MAX( rzero , SIGN( rone, - ( 1.0 - pfrld(ji,jj) ) ) ) |
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111 | ifvt = zinda * MAX( rzero , SIGN( rone, - phicif(ji,jj) ) ) |
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112 | i1mfr = 1.0 - MAX( rzero , SIGN( rone, - ( 1.0 - frld(ji,jj) ) ) ) |
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113 | idfr = 1.0 - MAX( rzero , SIGN( rone, frld(ji,jj) - pfrld(ji,jj) ) ) |
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114 | iflt = zinda * (1 - i1mfr) * (1 - ifvt ) |
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115 | ial = ifvt * i1mfr + ( 1 - ifvt ) * idfr |
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116 | iadv = ( 1 - i1mfr ) * zinda |
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117 | ifral = ( 1 - i1mfr * ( 1 - ial ) ) |
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118 | ifrdv = ( 1 - ifral * ( 1 - ial ) ) * iadv |
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119 | ! computation the solar flux at ocean surface |
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120 | zqsr = pfrld(ji,jj) * qsr(ji,jj) + ( 1. - pfrld(ji,jj) ) * fstric(ji,jj) |
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121 | ! computation the non solar heat flux at ocean surface |
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122 | zqns = - ( 1. - thcm(ji,jj) ) * zqsr & ! part of the solar energy used in leads |
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123 | & + iflt * ( fscmbq(ji,jj) + ffltbif(ji,jj) ) & |
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124 | & + ifral * ( ial * qcmif(ji,jj) + (1 - ial) * qldif(ji,jj) ) / rdt_ice & |
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125 | & + ifrdv * ( qfvbq(ji,jj) + qdtcn(ji,jj) ) / rdt_ice |
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126 | |
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127 | fsbbq(ji,jj) = ( 1.0 - ( ifvt + iflt ) ) * fscmbq(ji,jj) ! ??? |
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128 | |
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129 | qsr (ji,jj) = zqsr ! solar heat flux |
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130 | qns (ji,jj) = zqns - fdtcn(ji,jj) ! non solar heat flux |
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131 | END DO |
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132 | END DO |
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133 | |
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134 | !------------------------------------------! |
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135 | ! mass flux at the ocean surface ! |
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136 | !------------------------------------------! |
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137 | |
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138 | !!gm |
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139 | !!gm CAUTION |
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140 | !!gm re-verifies the emp & emps expression, especially the absence of 1-frld on zfm |
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141 | !!gm |
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142 | DO jj = 1, jpj |
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143 | DO ji = 1, jpi |
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144 | |
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145 | ! computing freshwater exchanges at the ice/ocean interface |
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146 | zemp = + emp(ji,jj) * frld(ji,jj) & ! e-p budget over open ocean fraction |
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147 | ! ! ice-covered fraction: |
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148 | & - tprecip(ji,jj) * ( 1. - frld(ji,jj) ) & ! liquid precipitation reaches directly the ocean |
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149 | & + sprecip(ji,jj) * ( 1. - pfrld(ji,jj) ) & ! taking into account change in ice cover within the time step |
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150 | & + rdmsnif(ji,jj) / rdt_ice ! freshwaterflux due to snow melting |
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151 | |
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152 | !!gm old zemp = + evap(ji,jj) * frld(ji,jj) & ! evaporation over oceanic fraction |
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153 | !!gm old & - tprecip(ji,jj) & ! total precipitation |
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154 | !!gm old & + sprecip(ji,jj) * ( 1. - pfrld(ji,jj) ) & ! remov. snow precip over ice (store over sea-ice) |
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155 | !!gm old & + rdmsnif(ji,jj) / rdt_ice ! freshwaterflux due to snow melting |
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156 | |
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157 | ! computing salt exchanges at the ice/ocean interface |
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158 | zfons = ( soce - sice ) * ( rdmicif(ji,jj) / rdt_ice ) |
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159 | |
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160 | ! converting the salt flux from ice to a freshwater flux from ocean |
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161 | !!gm old zfm = zfons / ( sss_io(ji,jj) + epsi16 ) |
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162 | zfm = zfons / ( sss_m(ji,jj) + epsi16 ) |
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163 | |
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164 | emps(ji,jj) = zemp + zfm ! surface ocean concentration/dilution effect (use on SSS evolution) |
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165 | emp (ji,jj) = zemp ! surface ocean volume flux (use on sea-surface height evolution) |
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166 | |
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167 | END DO |
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168 | END DO |
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169 | |
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170 | IF( lk_dynspg_rl ) emp (:,:) = emps(:,:) ! rigid-lid formulation : emp = emps |
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171 | |
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172 | !------------------------------------------! |
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173 | ! momentum flux at the ocean surface ! |
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174 | !------------------------------------------! |
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175 | |
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176 | IF ( ln_limdyn ) THEN ! Update the stress over ice-over area (only in ice-dynamic case) |
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177 | ! ! otherwise the atmosphere-ocean stress is used everywhere |
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178 | |
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179 | ! ... ice stress over ocean with a ice-ocean rotation angle (at I-point) |
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180 | !CDIR NOVERRCHK |
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181 | DO jj = 1, jpj |
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182 | !CDIR NOVERRCHK |
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183 | DO ji = 1, jpi |
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184 | ! ... change the cosinus angle sign in the south hemisphere |
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185 | zsang = SIGN(1.e0, gphif(ji-1,jj-1) ) * sangvg |
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186 | ! ... ice velocity relative to the ocean |
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187 | zu_io = u_ice(ji,jj) - u_oce(ji,jj) |
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188 | zv_io = v_ice(ji,jj) - v_oce(ji,jj) |
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189 | zmod = SQRT( zu_io * zu_io + zv_io * zv_io ) |
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190 | ! ... ice stress over ocean with a ice-ocean rotation angle (at I-point) |
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191 | ztio_u(ji,jj) = cw * zmod * ( cangvg * zu_io - zsang * zv_io ) |
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192 | ztio_v(ji,jj) = cw * zmod * ( cangvg * zv_io + zsang * zu_io ) |
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193 | ! |
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194 | END DO |
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195 | END DO |
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196 | |
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197 | DO jj = 2, jpjm1 |
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198 | DO ji = 2, jpim1 |
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199 | ! ... ice-cover wheighted ice-ocean stress at U and V-points (from I-point values) |
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200 | zutau = 0.5 * ( ztio_u(ji+1,jj) + ztio_u(ji+1,jj+1) ) |
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201 | zvtau = 0.5 * ( ztio_v(ji,jj+1) + ztio_u(ji+1,jj+1) ) |
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202 | ! ... open-ocean (lead) fraction at U- & V-points (from T-point values) |
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203 | zfrldu = 0.5 * ( frld (ji,jj) + frld (ji+1,jj ) ) |
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204 | zfrldv = 0.5 * ( frld (ji,jj) + frld (ji ,jj+1) ) |
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205 | ! update surface ocean stress |
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206 | utau(ji,jj) = zfrldu * utau(ji,jj) + ( 1. - zfrldu ) * zutau |
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207 | vtau(ji,jj) = zfrldv * vtau(ji,jj) + ( 1. - zfrldv ) * zvtau |
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208 | ! |
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209 | END DO |
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210 | END DO |
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211 | |
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212 | ! boundary condition on the stress (utau,vtau) |
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213 | CALL lbc_lnk( utau, 'U', -1. ) |
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214 | CALL lbc_lnk( vtau, 'V', -1. ) |
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215 | |
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216 | ENDIF |
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217 | |
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218 | #if defined key_coupled |
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219 | !------------------------------------------------! |
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220 | ! Computation of snow/ice and ocean albedo ! |
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221 | !------------------------------------------------! |
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222 | zalb (:,:) = 0.e0 |
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223 | zalcn (:,:) = 0.e0 |
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224 | zalbp (:,:) = 0.e0 |
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225 | zaldum(:,:) = 0.e0 |
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226 | |
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227 | CALL flx_blk_albedo( zalb, zalcn, zalbp, zaldum ) |
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228 | |
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229 | alb_ice(:,:) = 0.5 * zalbp(:,:) + 0.5 * zalb (:,:) ! Ice albedo (mean clear and overcast skys) |
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230 | #endif |
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231 | |
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232 | IF(ln_ctl) THEN |
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233 | CALL prt_ctl(tab2d_1=qsr , clinfo1=' lim_sbc: qsr : ', tab2d_2=qns , clinfo2=' qns : ') |
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234 | CALL prt_ctl(tab2d_1=emp , clinfo1=' lim_sbc: emp : ', tab2d_2=emps, clinfo2=' emps : ') |
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235 | CALL prt_ctl(tab2d_1=utau, clinfo1=' lim_sbc: utau : ', tab2d_2=vtau, clinfo2=' vtau : ') |
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236 | !!gm tn_ice ??? what is it now? |
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237 | !!gm CALL prt_ctl(tab2d_1=freeze, clinfo1=' lim_sbc: freeze : ', tab2d_2=tn_ice , clinfo2=' tn_ice : ') |
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238 | ENDIF |
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239 | |
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240 | END SUBROUTINE lim_sbc |
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241 | |
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242 | #else |
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243 | !!---------------------------------------------------------------------- |
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244 | !! Default option : Dummy module NO LIM sea-ice model |
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245 | !!---------------------------------------------------------------------- |
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246 | CONTAINS |
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247 | SUBROUTINE lim_sbc ! Dummy routine |
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248 | END SUBROUTINE lim_sbc |
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249 | #endif |
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250 | |
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251 | !!====================================================================== |
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252 | END MODULE limsbc |
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