1 | MODULE trasbc |
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2 | !!============================================================================== |
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3 | !! *** MODULE trasbc *** |
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4 | !! Ocean active tracers: surface boundary condition |
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5 | !!============================================================================== |
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6 | !! History : OPA ! 2998-10 (G. Madec, G. Roullet, M. Imbard) Original code |
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7 | !! 8.2 ! 2001-02 (D. Ludicone) sea ice and free surface |
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8 | !! NEMO 1.0 ! 2002-06 (G. Madec) F90: Free form and module |
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9 | !! 3.3 ! 2010-04 (M. Leclair, G. Madec) Forcing averaged over 2 time steps |
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10 | !!---------------------------------------------------------------------- |
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11 | |
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12 | !!---------------------------------------------------------------------- |
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13 | !! tra_sbc : update the tracer trend at ocean surface |
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14 | !!---------------------------------------------------------------------- |
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15 | USE oce ! ocean dynamics and active tracers |
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16 | USE sbc_oce ! surface boundary condition: ocean |
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17 | USE dom_oce ! ocean space domain variables |
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18 | USE phycst ! physical constant |
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19 | USE traqsr ! solar radiation penetration |
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20 | USE trdmod ! ocean trends |
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21 | USE trdmod_oce ! ocean variables trends |
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22 | USE in_out_manager ! I/O manager |
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23 | USE prtctl ! Print control |
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24 | |
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25 | IMPLICIT NONE |
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26 | PRIVATE |
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27 | |
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28 | PUBLIC tra_sbc ! routine called by step.F90 |
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29 | |
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30 | !! * Substitutions |
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31 | # include "domzgr_substitute.h90" |
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32 | # include "vectopt_loop_substitute.h90" |
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33 | !!---------------------------------------------------------------------- |
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34 | !! NEMO/OPA 3.3 , LOCEAN-IPSL (2010) |
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35 | !! $Id$ |
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36 | !! Software governed by the CeCILL licence (modipsl/doc/NEMO_CeCILL.txt) |
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37 | !!---------------------------------------------------------------------- |
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38 | |
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39 | CONTAINS |
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40 | |
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41 | SUBROUTINE tra_sbc ( kt ) |
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42 | !!---------------------------------------------------------------------- |
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43 | !! *** ROUTINE tra_sbc *** |
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44 | !! |
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45 | !! ** Purpose : Compute the tracer surface boundary condition trend of |
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46 | !! (flux through the interface, concentration/dilution effect) |
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47 | !! and add it to the general trend of tracer equations. |
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48 | !! |
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49 | !! ** Method : Following Roullet and Madec (2000), the air-sea flux |
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50 | !! can be divided into three effects: |
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51 | !! (1) Fext, external forcing; |
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52 | !! (2) Fwi, concentration/dilution effect due to water exchanged |
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53 | !! at the surface by evaporation, precipitations and runoff (E-P-R); |
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54 | !! (3) Fwe, tracer carried with the water that is exchanged. |
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55 | !! |
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56 | !! Fext, flux through the air-sea interface for temperature and salt: |
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57 | !! - temperature : heat flux q (w/m2). If penetrative solar |
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58 | !! radiation q is only the non solar part of the heat flux, the |
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59 | !! solar part is added in traqsr.F routine. |
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60 | !! ta = ta + q /(rau0 rcp e3t) for k=1 |
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61 | !! - salinity : only salt flux exchanged with sea-ice |
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62 | !! |
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63 | !! The formulation for Fwb and Fwi vary according to the free |
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64 | !! surface formulation (linear or variable volume). |
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65 | !! * Linear free surface |
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66 | !! The surface freshwater flux modifies the ocean volume |
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67 | !! and thus the concentration of a tracer and the temperature. |
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68 | !! First order of the effect of surface freshwater exchange |
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69 | !! for salinity, it can be neglected on temperature (especially |
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70 | !! as the temperature of precipitations and runoffs is usually |
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71 | !! unknown). |
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72 | !! - temperature : we assume that the temperature of both |
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73 | !! precipitations and runoffs is equal to the SST, thus there |
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74 | !! is no additional flux since in this case, the concentration |
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75 | !! dilution effect is balanced by the net heat flux associated |
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76 | !! to the freshwater exchange (Fwe+Fwi=0): |
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77 | !! (Tp P - Te E) + SST (P-E) = 0 when Tp=Te=SST |
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78 | !! - salinity : evaporation, precipitation and runoff |
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79 | !! water has a zero salinity (Fwe=0), thus only Fwi remains: |
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80 | !! sa = sa + emp * sn / e3t for k=1 |
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81 | !! where emp, the surface freshwater budget (evaporation minus |
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82 | !! precipitation minus runoff) given in kg/m2/s is divided |
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83 | !! by 1035 kg/m3 (density of ocena water) to obtain m/s. |
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84 | !! Note: even though Fwe does not appear explicitly for |
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85 | !! temperature in this routine, the heat carried by the water |
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86 | !! exchanged through the surface is part of the total heat flux |
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87 | !! forcing and must be taken into account in the global heat |
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88 | !! balance). |
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89 | !! * nonlinear free surface (variable volume, lk_vvl) |
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90 | !! contrary to the linear free surface case, Fwi is properly |
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91 | !! taken into account by using the true layer thicknesses to |
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92 | !! calculate tracer content and advection. There is no need to |
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93 | !! deal with it in this routine. |
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94 | !! - temperature: Fwe=SST (P-E+R) is added to Fext. |
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95 | !! - salinity: Fwe = 0, there is no surface flux of salt. |
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96 | !! |
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97 | !! ** Action : - Update the 1st level of (ta,sa) with the trend associated |
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98 | !! with the tracer surface boundary condition |
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99 | !! - save the trend it in ttrd ('key_trdtra') |
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100 | !!---------------------------------------------------------------------- |
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101 | USE oce, ONLY : ztrdt => ua ! use ua as 3D workspace |
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102 | USE oce, ONLY : ztrds => va ! use va as 3D workspace |
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103 | !! |
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104 | INTEGER, INTENT(in) :: kt ! ocean time-step index |
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105 | !! |
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106 | INTEGER :: ji, jj ! dummy loop indices |
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107 | REAL(wp) :: zsrau, zse3t ! temporary scalars |
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108 | !!---------------------------------------------------------------------- |
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109 | |
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110 | IF( kt == nit000 ) THEN |
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111 | IF(lwp) WRITE(numout,*) |
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112 | IF(lwp) WRITE(numout,*) 'tra_sbc : TRAcer Surface Boundary Condition' |
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113 | IF(lwp) WRITE(numout,*) '~~~~~~~ ' |
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114 | ENDIF |
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115 | |
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116 | zsrau = 1. / rau0 ! initialization |
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117 | #if defined key_zco |
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118 | zse3t = 1. / e3t_0(1) |
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119 | #endif |
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120 | |
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121 | IF( l_trdtra ) THEN ! Save ta and sa trends |
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122 | ztrdt(:,:,:) = ta(:,:,:) |
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123 | ztrds(:,:,:) = sa(:,:,:) |
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124 | ENDIF |
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125 | |
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126 | !!gm IF( .NOT.ln_traqsr ) qsr(:,:) = 0.e0 ! no solar radiation penetration |
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127 | IF( .NOT.ln_traqsr ) THEN ! no solar radiation penetration |
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128 | qns(:,:) = qns(:,:) + qsr(:,:) ! total heat flux in qns |
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129 | qsr(:,:) = 0.e0 ! qsr set to zero |
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130 | IF( kt == nit000 ) THEN ! idem on before field at nit000 |
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131 | qsr_b(:,:) = 0.e0 |
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132 | ENDIF |
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133 | ENDIF |
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134 | |
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135 | ! ! ---------------------- ! |
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136 | IF( lk_vvl ) THEN ! Variable Volume case ! |
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137 | ! ! ---------------------- ! |
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138 | !!gm BUG : in key_vvl emps must be modified to only include the salt flux due to sea-ice freezing/melting |
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139 | !!gm otherwise this flux will be missing ==> modification required in limsbc, limsbc_2 and CICE interface.s |
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140 | IF ( neuler == 0 .AND. kt == nit000 ) THEN |
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141 | DO jj = 2, jpj |
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142 | DO ji = fs_2, fs_jpim1 ! vector opt. |
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143 | ! temperature : heat flux + cooling/heating effet of EMP flux |
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144 | sbc_trd_hc_n(ji,jj) = ro0cpr * qns(ji,jj) - zsrau * emp(ji,jj) * tn(ji,jj,1) |
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145 | #if ! defined key_zco |
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146 | zse3t = 1. / fse3t(ji,jj,1) |
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147 | #endif |
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148 | ta(ji,jj,1) = ta(ji,jj,1) + zse3t * sbc_trd_hc_n(ji,jj) |
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149 | END DO |
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150 | END DO |
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151 | ELSE |
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152 | DO jj = 2, jpj |
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153 | DO ji = fs_2, fs_jpim1 ! vector opt. |
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154 | ! temperature : heat flux + cooling/heating effet of EMP flux |
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155 | sbc_trd_hc_n(ji,jj) = ro0cpr * qns(ji,jj) - zsrau * emp(ji,jj) * tn(ji,jj,1) |
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156 | #if ! defined key_zco |
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157 | zse3t = 1. / fse3t(ji,jj,1) |
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158 | #endif |
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159 | ta(ji,jj,1) = ta(ji,jj,1) + 0.5 * ( sbc_trd_hc_b(ji,jj) + sbc_trd_hc_n(ji,jj) ) * zse3t |
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160 | END DO |
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161 | END DO |
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162 | ENDIF |
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163 | ! ! ---------------------- ! |
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164 | ELSE ! Constant Volume case ! |
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165 | ! ! ---------------------- ! |
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166 | IF ( neuler == 0 .AND. kt == nit000 ) THEN |
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167 | DO jj = 2, jpj |
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168 | DO ji = fs_2, fs_jpim1 ! vector opt. |
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169 | ! temperature : heat flux |
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170 | sbc_trd_hc_n(ji,jj) = ro0cpr * qns(ji,jj) |
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171 | ! salinity : salt flux + concent./dilut. effect (both in emps) |
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172 | sbc_trd_sc_n(ji,jj) = zsrau * emps(ji,jj) * sn(ji,jj,1) |
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173 | #if ! defined key_zco |
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174 | zse3t = 1. / fse3t(ji,jj,1) |
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175 | #endif |
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176 | ta(ji,jj,1) = ta(ji,jj,1) + sbc_trd_hc_n(ji,jj) * zse3t |
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177 | sa(ji,jj,1) = sa(ji,jj,1) + sbc_trd_sc_n(ji,jj) * zse3t |
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178 | END DO |
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179 | END DO |
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180 | ELSE |
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181 | DO jj = 2, jpj |
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182 | DO ji = fs_2, fs_jpim1 ! vector opt. |
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183 | ! temperature : heat flux |
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184 | sbc_trd_hc_n(ji,jj) = ro0cpr * qns(ji,jj) |
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185 | ! salinity : salt flux + concent./dilut. effect (both in emps) |
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186 | sbc_trd_sc_n(ji,jj) = zsrau * emps(ji,jj) * sn(ji,jj,1) |
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187 | #if ! defined key_zco |
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188 | zse3t = 1. / fse3t(ji,jj,1) |
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189 | #endif |
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190 | ! temperature : heat flux |
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191 | ta(ji,jj,1) = ta(ji,jj,1) + 0.5 * ( sbc_trd_hc_b(ji,jj) + sbc_trd_hc_n(ji,jj) ) * zse3t |
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192 | sa(ji,jj,1) = sa(ji,jj,1) + 0.5 * ( sbc_trd_sc_b(ji,jj) + sbc_trd_sc_n(ji,jj) ) * zse3t |
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193 | END DO |
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194 | END DO |
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195 | ENDIF |
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196 | ! |
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197 | ENDIF |
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198 | |
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199 | IF( l_trdtra ) THEN ! save the sbc trends for diagnostic |
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200 | ztrdt(:,:,:) = ta(:,:,:) - ztrdt(:,:,:) |
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201 | ztrds(:,:,:) = sa(:,:,:) - ztrds(:,:,:) |
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202 | CALL trd_mod(ztrdt, ztrds, jptra_trd_nsr, 'TRA', kt) |
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203 | ENDIF |
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204 | ! ! control print |
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205 | IF(ln_ctl) CALL prt_ctl( tab3d_1=ta, clinfo1=' sbc - Ta: ', mask1=tmask, & |
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206 | & tab3d_2=sa, clinfo2= ' Sa: ', mask2=tmask, clinfo3='tra' ) |
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207 | ! |
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208 | END SUBROUTINE tra_sbc |
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209 | |
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210 | !!====================================================================== |
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211 | END MODULE trasbc |
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