1 | MODULE lmdz_lscp_poprecip |
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2 | !---------------------------------------------------------------- |
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3 | ! Module for the process-oriented treament of precipitation |
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4 | ! that are called in LSCP |
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5 | ! Authors: Atelier Nuage (G. Riviere, L. Raillard, M. Wimmer, |
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6 | ! N. Dutrievoz, E. Vignon, A. Borella, et al.) |
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7 | ! Jan. 2024 |
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8 | |
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9 | |
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10 | IMPLICIT NONE |
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11 | |
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12 | CONTAINS |
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13 | |
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14 | !---------------------------------------------------------------- |
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15 | ! Computes the processes-oriented precipitation formulations for |
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16 | ! evaporation and sublimation |
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17 | ! |
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18 | SUBROUTINE poprecip_evapsub( & |
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19 | klon, dtime, iftop, paprsdn, paprsup, pplay, temp, tempupnew, qvap, & |
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20 | qprecip, precipfracclr, precipfraccld, & |
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21 | rain, rainclr, raincld, snow, snowclr, snowcld, dqreva, dqssub & |
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22 | ) |
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23 | |
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24 | USE lmdz_lscp_ini, ONLY : prt_level, lunout |
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25 | USE lmdz_lscp_ini, ONLY : coef_eva, coef_sub, expo_eva, expo_sub, thresh_precip_frac |
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26 | USE lmdz_lscp_ini, ONLY : RCPD, RLSTT, RLVTT, RLMLT, RVTMP2, RTT, RD, RG |
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27 | USE lmdz_lscp_tools, ONLY : calc_qsat_ecmwf |
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28 | |
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29 | IMPLICIT NONE |
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30 | |
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31 | |
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32 | INTEGER, INTENT(IN) :: klon !--number of horizontal grid points [-] |
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33 | REAL, INTENT(IN) :: dtime !--time step [s] |
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34 | LOGICAL, INTENT(IN) :: iftop !--if top of the column |
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35 | |
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36 | |
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37 | REAL, INTENT(IN), DIMENSION(klon) :: paprsdn !--pressure at the bottom interface of the layer [Pa] |
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38 | REAL, INTENT(IN), DIMENSION(klon) :: paprsup !--pressure at the top interface of the layer [Pa] |
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39 | REAL, INTENT(IN), DIMENSION(klon) :: pplay !--pressure in the middle of the layer [Pa] |
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40 | |
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41 | REAL, INTENT(INOUT), DIMENSION(klon) :: temp !--current temperature [K] |
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42 | REAL, INTENT(INOUT), DIMENSION(klon) :: tempupnew !--updated temperature of the overlying layer [K] |
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43 | |
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44 | REAL, INTENT(INOUT), DIMENSION(klon) :: qvap !--current water vapor specific humidity (includes evaporated qi and ql) [kg/kg] |
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45 | REAL, INTENT(INOUT), DIMENSION(klon) :: qprecip !--specific humidity in the precipitation falling from the upper layer [kg/kg] |
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46 | |
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47 | REAL, INTENT(INOUT), DIMENSION(klon) :: precipfracclr !--fraction of precipitation in the clear sky IN THE LAYER ABOVE [-] |
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48 | REAL, INTENT(INOUT), DIMENSION(klon) :: precipfraccld !--fraction of precipitation in the cloudy air IN THE LAYER ABOVE [-] |
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49 | |
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50 | REAL, INTENT(INOUT), DIMENSION(klon) :: rain !--flux of rain gridbox-mean coming from the layer above [kg/s/m2] |
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51 | REAL, INTENT(INOUT), DIMENSION(klon) :: rainclr !--flux of rain gridbox-mean in clear sky coming from the layer above [kg/s/m2] |
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52 | REAL, INTENT(IN), DIMENSION(klon) :: raincld !--flux of rain gridbox-mean in cloudy air coming from the layer above [kg/s/m2] |
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53 | REAL, INTENT(INOUT), DIMENSION(klon) :: snow !--flux of snow gridbox-mean coming from the layer above [kg/s/m2] |
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54 | REAL, INTENT(INOUT), DIMENSION(klon) :: snowclr !--flux of snow gridbox-mean in clear sky coming from the layer above [kg/s/m2] |
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55 | REAL, INTENT(IN), DIMENSION(klon) :: snowcld !--flux of snow gridbox-mean in cloudy air coming from the layer above [kg/s/m2] |
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56 | |
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57 | REAL, INTENT(OUT), DIMENSION(klon) :: dqreva !--rain tendency due to evaporation [kg/kg/s] |
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58 | REAL, INTENT(OUT), DIMENSION(klon) :: dqssub !--snow tendency due to sublimation [kg/kg/s] |
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59 | |
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60 | |
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61 | |
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62 | |
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63 | !--Integer for interating over klon |
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64 | INTEGER :: i |
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65 | !--hum_to_flux: coef to convert a specific quantity to a flux |
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66 | REAL, DIMENSION(klon) :: hum_to_flux |
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67 | |
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68 | !--Saturation values |
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69 | REAL, DIMENSION(klon) :: qzero, qsat, dqsat, qsatl, dqsatl, qsati, dqsati |
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70 | !--Fluxes tendencies because of evaporation and sublimation |
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71 | REAL :: dprecip_evasub_max, draineva, dsnowsub, dprecip_evasub_tot |
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72 | !--Specific humidity tendencies because of evaporation and sublimation |
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73 | REAL :: dqrevap, dqssubl |
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74 | !--Specific heat constant |
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75 | REAL :: cpair, cpw |
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76 | |
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77 | !--Initialisation |
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78 | qzero(:) = 0. |
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79 | dqreva(:) = 0. |
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80 | dqssub(:) = 0. |
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81 | dqrevap = 0. |
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82 | dqssubl = 0. |
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83 | |
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84 | !-- hum_to_flux = rho * dz/dt = 1 / g * dP/dt |
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85 | hum_to_flux(:) = ( paprsdn(:) - paprsup(:) ) / RG / dtime |
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86 | |
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87 | !--Calculation of saturation specific humidity |
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88 | !--depending on temperature: |
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89 | CALL calc_qsat_ecmwf(klon,temp(:),qzero(:),pplay(:),RTT,0,.false.,qsat(:),dqsat(:)) |
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90 | !--wrt liquid water |
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91 | CALL calc_qsat_ecmwf(klon,temp(:),qzero(:),pplay(:),RTT,1,.false.,qsatl(:),dqsatl(:)) |
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92 | !--wrt ice |
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93 | CALL calc_qsat_ecmwf(klon,temp(:),qzero(:),pplay(:),RTT,2,.false.,qsati(:),dqsati(:)) |
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94 | |
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95 | |
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96 | |
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97 | !--First step consists in "thermalizing" the layer: |
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98 | !--as the flux of precip from layer above "advects" some heat (as the precip is at the temperature |
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99 | !--of the overlying layer) we recalculate a mean temperature that both the air and the precip in the |
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100 | !--layer have. |
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101 | |
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102 | IF (iftop) THEN |
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103 | |
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104 | DO i = 1, klon |
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105 | qprecip(i) = 0. |
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106 | ENDDO |
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107 | |
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108 | ELSE |
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109 | |
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110 | DO i = 1, klon |
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111 | !--No condensed water so cp=cp(vapor+dry air) |
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112 | !-- RVTMP2=rcpv/rcpd-1 |
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113 | cpair = RCPD * ( 1. + RVTMP2 * qvap(i) ) |
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114 | cpw = RCPD * RVTMP2 |
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115 | !--qprecip has to be thermalized with |
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116 | !--layer's air so that precipitation at the ground has the |
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117 | !--same temperature as the lowermost layer |
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118 | !--we convert the flux into a specific quantity qprecip |
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119 | qprecip(i) = ( rain(i) + snow(i) ) / hum_to_flux(i) |
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120 | !-- t(i,k+1) + d_t(i,k+1): new temperature of the overlying layer |
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121 | temp(i) = ( tempupnew(i) * qprecip(i) * cpw + cpair * temp(i) ) & |
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122 | / ( cpair + qprecip(i) * cpw ) |
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123 | ENDDO |
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124 | |
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125 | ENDIF |
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126 | |
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127 | |
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128 | DO i = 1, klon |
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129 | |
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130 | !--If there is precipitation from the layer above |
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131 | IF ( ( rain(i) + snow(i) ) .GT. 0. ) THEN |
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132 | |
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133 | !--Evaporation of liquid precipitation coming from above |
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134 | !--in the clear sky only |
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135 | !--dP/dz=beta*(1-q/qsat)*(P**expo_eva) (lines 1-2) |
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136 | !--multiplying by dz = - dP / g / rho (line 3-4) |
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137 | !--formula from Sundqvist 1988, Klemp & Wilhemson 1978 |
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138 | |
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139 | draineva = - precipfracclr(i) * coef_eva * (1. - qvap(i) / qsatl(i)) & |
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140 | * ( rainclr(i) / MAX(thresh_precip_frac, precipfracclr(i)) ) ** expo_eva & |
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141 | * temp(i) * RD / pplay(i) & |
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142 | * ( paprsdn(i) - paprsup(i) ) / RG |
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143 | |
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144 | !--Evaporation is limited by 0 and by the total water amount in |
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145 | !--the precipitation |
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146 | draineva = MIN(0., MAX(draineva, -rainclr(i))) |
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147 | |
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148 | |
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149 | !--Sublimation of the solid precipitation coming from above |
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150 | !--(same formula as for liquid precip) |
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151 | dsnowsub = - precipfracclr(i) * coef_sub * (1. - qvap(i) / qsati(i)) & |
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152 | * ( snowclr(i) / MAX(thresh_precip_frac, precipfracclr(i)) ) ** expo_sub & |
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153 | * temp(i) * RD / pplay(i) & |
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154 | * ( paprsdn(i) - paprsup(i) ) / RG |
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155 | |
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156 | !--Sublimation is limited by 0 and by the total water amount in |
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157 | !--the precipitation |
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158 | ! TODO: change max when we will allow for vapor deposition in supersaturated regions |
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159 | dsnowsub = MIN(0., MAX(dsnowsub, -snowclr(i))) |
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160 | |
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161 | !--Evaporation limit: we ensure that the layer's fraction below |
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162 | !--the clear sky does not reach saturation. In this case, we |
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163 | !--redistribute the maximum flux dprecip_evasub_max conserving the ratio liquid/ice |
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164 | !--Max evaporation is computed not to saturate the clear sky precip fraction |
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165 | !--(i.e., the fraction where evaporation occurs) |
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166 | !--It is expressed as a max flux dprecip_evasub_max |
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167 | |
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168 | dprecip_evasub_max = MIN(0., ( qvap(i) - qsat(i) ) * precipfracclr(i)) & |
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169 | * hum_to_flux(i) |
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170 | dprecip_evasub_tot = draineva + dsnowsub |
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171 | |
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172 | !--Barriers |
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173 | !--If activates if the total is LOWER than the max because |
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174 | !--everything is negative |
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175 | IF ( dprecip_evasub_tot .LT. dprecip_evasub_max ) THEN |
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176 | draineva = dprecip_evasub_max * draineva / dprecip_evasub_tot |
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177 | dsnowsub = dprecip_evasub_max * dsnowsub / dprecip_evasub_tot |
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178 | ENDIF |
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179 | |
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180 | |
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181 | !--New solid and liquid precipitation fluxes after evap and sublimation |
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182 | dqrevap = draineva / hum_to_flux(i) |
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183 | dqssubl = dsnowsub / hum_to_flux(i) |
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184 | |
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185 | |
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186 | !--Vapor is updated after evaporation/sublimation (it is increased) |
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187 | qvap(i) = qvap(i) - dqrevap - dqssubl |
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188 | !--qprecip is the total condensed water in the precip flux (it is decreased) |
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189 | qprecip(i) = qprecip(i) + dqrevap + dqssubl |
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190 | !--Air and precip temperature (i.e., gridbox temperature) |
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191 | !--is updated due to latent heat cooling |
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192 | temp(i) = temp(i) & |
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193 | + dqrevap * RLVTT / RCPD & |
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194 | / ( 1. + RVTMP2 * ( qvap(i) + qprecip(i) ) ) & |
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195 | + dqssubl * RLSTT / RCPD & |
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196 | / ( 1. + RVTMP2 * ( qvap(i) + qprecip(i) ) ) |
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197 | |
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198 | !--Add tendencies |
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199 | rainclr(i) = rainclr(i) + draineva |
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200 | snowclr(i) = snowclr(i) + dsnowsub |
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201 | |
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202 | !--If there is no more precip fluxes, the precipitation fraction in clear |
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203 | !--sky is set to 0 |
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204 | IF ( ( rainclr(i) + snowclr(i) ) .LE. 0. ) precipfracclr(i) = 0. |
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205 | |
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206 | !--Calculation of the total fluxes |
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207 | rain(i) = rainclr(i) + raincld(i) |
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208 | snow(i) = snowclr(i) + snowcld(i) |
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209 | |
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210 | ELSE |
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211 | !--If no precip, we reinitialize the cloud fraction used for the precip to 0 |
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212 | precipfraccld(i) = 0. |
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213 | precipfracclr(i) = 0. |
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214 | |
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215 | ENDIF ! ( ( rain(i) + snow(i) ) .GT. 0. ) |
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216 | |
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217 | !--Diagnostic tendencies |
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218 | dqssub(i) = dqssubl / dtime |
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219 | dqreva(i) = dqrevap / dtime |
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220 | |
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221 | ENDDO ! loop on klon |
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222 | |
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223 | |
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224 | END SUBROUTINE poprecip_evapsub |
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225 | |
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226 | !---------------------------------------------------------------- |
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227 | ! Computes the processes-oriented precipitation formulations for |
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228 | ! - autoconversion (auto) via a deposition process |
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229 | ! - aggregation (agg) |
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230 | ! - riming (rim) |
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231 | ! - collection (col) |
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232 | ! - melting (melt) |
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233 | ! - freezing (freez) |
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234 | ! |
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235 | SUBROUTINE poprecip_postcld( & |
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236 | klon, dtime, paprsdn, paprsup, pplay, ctot_vol, ptconv, & |
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237 | temp, qvap, qliq, qice, icefrac, cldfra, & |
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238 | precipfracclr, precipfraccld, & |
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239 | rain, rainclr, raincld, snow, snowclr, snowcld, & |
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240 | qraindiag, qsnowdiag, dqrauto, dqrcol, dqrmelt, dqrfreez, & |
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241 | dqsauto, dqsagg, dqsrim, dqsmelt, dqsfreez) |
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242 | |
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243 | USE lmdz_lscp_ini, ONLY : prt_level, lunout |
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244 | USE lmdz_lscp_ini, ONLY : RCPD, RLSTT, RLVTT, RLMLT, RVTMP2, RTT, RD, RG, RPI |
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245 | USE lmdz_lscp_tools, ONLY : calc_qsat_ecmwf |
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246 | |
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247 | USE lmdz_lscp_ini, ONLY : cld_lc_con, cld_tau_con, cld_expo_con, seuil_neb, & |
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248 | cld_lc_lsc, cld_tau_lsc, cld_expo_lsc, rain_int_min, & |
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249 | thresh_precip_frac, gamma_col, gamma_agg, gamma_rim, & |
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250 | rho_rain, rho_snow, r_rain, r_snow, & |
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251 | tau_auto_snow_min, tau_auto_snow_max, & |
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252 | thresh_precip_frac, eps, air_thermal_conduct, & |
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253 | coef_ventil, alpha_freez, beta_freez, temp_nowater, & |
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254 | iflag_cloudth_vert, iflag_rain_incloud_vol, & |
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255 | cld_lc_lsc_snow, cld_lc_con_snow, gamma_freez, & |
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256 | rain_fallspeed_clr, rain_fallspeed_cld, & |
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257 | snow_fallspeed_clr, snow_fallspeed_cld |
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258 | |
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259 | |
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260 | IMPLICIT NONE |
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261 | |
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262 | INTEGER, INTENT(IN) :: klon !--number of horizontal grid points [-] |
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263 | REAL, INTENT(IN) :: dtime !--time step [s] |
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264 | |
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265 | REAL, INTENT(IN), DIMENSION(klon) :: paprsdn !--pressure at the bottom interface of the layer [Pa] |
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266 | REAL, INTENT(IN), DIMENSION(klon) :: paprsup !--pressure at the top interface of the layer [Pa] |
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267 | REAL, INTENT(IN), DIMENSION(klon) :: pplay !--pressure in the middle of the layer [Pa] |
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268 | |
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269 | REAL, INTENT(IN), DIMENSION(klon) :: ctot_vol !--volumic cloud fraction [-] |
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270 | LOGICAL, INTENT(IN), DIMENSION(klon) :: ptconv !--true if we are in a convective point |
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271 | |
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272 | REAL, INTENT(INOUT), DIMENSION(klon) :: temp !--current temperature [K] |
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273 | REAL, INTENT(INOUT), DIMENSION(klon) :: qvap !--current water vapor specific humidity [kg/kg] |
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274 | REAL, INTENT(INOUT), DIMENSION(klon) :: qliq !--current liquid water specific humidity [kg/kg] |
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275 | REAL, INTENT(INOUT), DIMENSION(klon) :: qice !--current ice water specific humidity [kg/kg] |
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276 | REAL, INTENT(IN), DIMENSION(klon) :: icefrac !--ice fraction [-] |
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277 | REAL, INTENT(IN), DIMENSION(klon) :: cldfra !--cloud fraction [-] |
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278 | |
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279 | REAL, INTENT(INOUT), DIMENSION(klon) :: precipfracclr !--fraction of precipitation in the clear sky IN THE LAYER ABOVE [-] |
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280 | REAL, INTENT(INOUT), DIMENSION(klon) :: precipfraccld !--fraction of precipitation in the cloudy air IN THE LAYER ABOVE [-] |
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281 | !--NB. at the end of the routine, becomes the fraction of precip |
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282 | !--in the current layer |
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283 | |
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284 | REAL, INTENT(INOUT), DIMENSION(klon) :: rain !--flux of rain gridbox-mean coming from the layer above [kg/s/m2] |
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285 | REAL, INTENT(INOUT), DIMENSION(klon) :: rainclr !--flux of rain gridbox-mean in clear sky coming from the layer above [kg/s/m2] |
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286 | REAL, INTENT(INOUT), DIMENSION(klon) :: raincld !--flux of rain gridbox-mean in cloudy air coming from the layer above [kg/s/m2] |
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287 | REAL, INTENT(INOUT), DIMENSION(klon) :: snow !--flux of snow gridbox-mean coming from the layer above [kg/s/m2] |
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288 | REAL, INTENT(INOUT), DIMENSION(klon) :: snowclr !--flux of snow gridbox-mean in clear sky coming from the layer above [kg/s/m2] |
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289 | REAL, INTENT(INOUT), DIMENSION(klon) :: snowcld !--flux of snow gridbox-mean in cloudy air coming from the layer above [kg/s/m2] |
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290 | |
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291 | REAL, INTENT(OUT), DIMENSION(klon) :: qraindiag !--DIAGNOSTIC specific rain content [kg/kg] |
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292 | REAL, INTENT(OUT), DIMENSION(klon) :: qsnowdiag !--DIAGNOSTIC specific snow content [kg/kg] |
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293 | REAL, INTENT(OUT), DIMENSION(klon) :: dqrcol !--rain tendendy due to collection by rain of liquid cloud droplets [kg/kg/s] |
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294 | REAL, INTENT(OUT), DIMENSION(klon) :: dqsagg !--snow tendency due to collection of lcoud ice by aggregation [kg/kg/s] |
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295 | REAL, INTENT(OUT), DIMENSION(klon) :: dqrauto !--rain tendency due to autoconversion of cloud liquid [kg/kg/s] |
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296 | REAL, INTENT(OUT), DIMENSION(klon) :: dqsauto !--snow tendency due to autoconversion of cloud ice [kg/kg/s] |
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297 | REAL, INTENT(OUT), DIMENSION(klon) :: dqsrim !--snow tendency due to riming [kg/kg/s] |
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298 | REAL, INTENT(OUT), DIMENSION(klon) :: dqsmelt !--snow tendency due to melting [kg/kg/s] |
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299 | REAL, INTENT(OUT), DIMENSION(klon) :: dqrmelt !--rain tendency due to melting [kg/kg/s] |
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300 | REAL, INTENT(OUT), DIMENSION(klon) :: dqsfreez !--snow tendency due to freezing [kg/kg/s] |
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301 | REAL, INTENT(OUT), DIMENSION(klon) :: dqrfreez !--rain tendency due to freezing [kg/kg/s] |
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302 | |
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303 | |
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304 | |
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305 | !--Local variables |
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306 | |
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307 | INTEGER :: i |
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308 | REAL, DIMENSION(klon) :: hum_to_flux |
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309 | REAL, DIMENSION(klon) :: qtot !--includes vap, liq, ice and precip |
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310 | |
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311 | !--Partition of the fluxes |
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312 | REAL :: dcldfra |
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313 | REAL :: precipfractot |
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314 | REAL :: dprecipfracclr, dprecipfraccld |
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315 | REAL :: drainclr, dsnowclr |
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316 | REAL :: draincld, dsnowcld |
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317 | |
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318 | !--Collection, aggregation and riming |
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319 | REAL :: eff_cldfra |
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320 | REAL :: coef_col, coef_agg, coef_rim, coef_tmp, qrain_tmp |
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321 | REAL :: Eff_rain_liq, Eff_snow_ice, Eff_snow_liq |
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322 | REAL :: dqlcol !--loss of liquid cloud content due to collection by rain [kg/kg/s] |
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323 | REAL :: dqiagg !--loss of ice cloud content due to collection by aggregation [kg/kg/s] |
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324 | REAL :: dqlrim !--loss of liquid cloud content due to riming on snow [kg/kg/s] |
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325 | |
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326 | !--Autoconversion |
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327 | REAL :: qthresh_auto_rain, tau_auto_rain, expo_auto_rain |
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328 | REAL :: qthresh_auto_snow, tau_auto_snow, expo_auto_snow |
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329 | REAL :: dqlauto !--loss of liquid cloud content due to autoconversion to rain [kg/kg/s] |
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330 | REAL :: dqiauto !--loss of ice cloud content due to autoconversion to snow [kg/kg/s] |
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331 | |
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332 | !--Melting |
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333 | REAL :: dqsmelt_max |
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334 | REAL :: nb_snowflake_clr, nb_snowflake_cld |
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335 | REAL :: capa_snowflake, temp_wetbulb |
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336 | REAL :: dqsclrmelt, dqscldmelt, dqstotmelt |
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337 | REAL, DIMENSION(klon) :: qzero, qsat, dqsat |
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338 | |
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339 | !--Freezing |
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340 | REAL :: dqrfreez_max |
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341 | REAL :: tau_freez |
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342 | REAL :: dqrclrfreez, dqrcldfreez, dqrtotfreez |
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343 | REAL :: coef_freez |
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344 | REAL :: dqifreez !--loss of ice cloud content due to collection of ice from rain [kg/kg/s] |
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345 | REAL :: Eff_rain_ice |
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346 | |
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347 | |
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348 | !--Initialisation of variables |
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349 | |
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350 | qzero(:) = 0. |
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351 | |
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352 | dqrcol(:) = 0. |
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353 | dqsagg(:) = 0. |
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354 | dqsauto(:) = 0. |
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355 | dqrauto(:) = 0. |
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356 | dqsrim(:) = 0. |
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357 | dqrmelt(:) = 0. |
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358 | dqsmelt(:) = 0. |
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359 | dqrfreez(:) = 0. |
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360 | dqsfreez(:) = 0. |
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361 | |
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362 | |
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363 | DO i = 1, klon |
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364 | |
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365 | !--Variables initialisation |
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366 | dqlcol = 0. |
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367 | dqiagg = 0. |
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368 | dqiauto = 0. |
---|
369 | dqlauto = 0. |
---|
370 | dqlrim = 0. |
---|
371 | dqifreez= 0. |
---|
372 | |
---|
373 | !--hum_to_flux: coef to convert a specific quantity to a flux |
---|
374 | !-- hum_to_flux = rho * dz/dt = 1 / g * dP/dt |
---|
375 | hum_to_flux(i) = ( paprsdn(i) - paprsup(i) ) / RG / dtime |
---|
376 | qtot(i) = qvap(i) + qliq(i) + qice(i) & |
---|
377 | + ( raincld(i) + rainclr(i) + snowcld(i) + snowclr(i) ) / hum_to_flux(i) |
---|
378 | |
---|
379 | !------------------------------------------------------------ |
---|
380 | !-- PRECIPITATION FRACTIONS UPDATE |
---|
381 | !------------------------------------------------------------ |
---|
382 | !--The goal of this routine is to reattribute precipitation fractions |
---|
383 | !--and fluxes to clear or cloudy air, depending on the variation of |
---|
384 | !--the cloud fraction on the vertical dimension. We assume a |
---|
385 | !--maximum-random overlap of the cloud cover (see Jakob and Klein, 2000, |
---|
386 | !--and LTP thesis, 2021) |
---|
387 | !--NB. in fact, we assume a maximum-random overlap of the total precip. frac |
---|
388 | |
---|
389 | !--Initialisation |
---|
390 | precipfractot = precipfracclr(i) + precipfraccld(i) |
---|
391 | |
---|
392 | !--Instead of using the cloud cover which was use in LTP thesis, we use the |
---|
393 | !--total precip. fraction to compute the maximum-random overlap. This is |
---|
394 | !--because all the information of the cloud cover is embedded into |
---|
395 | !--precipfractot, and this allows for taking into account the potential |
---|
396 | !--reduction of the precipitation fraction because either the flux is too |
---|
397 | !--small (see barrier at the end of poprecip_postcld) or the flux is completely |
---|
398 | !--evaporated (see barrier at the end of poprecip_precld) |
---|
399 | !--NB. precipfraccld(i) is here the cloud fraction of the layer above |
---|
400 | precipfractot = 1. - ( 1. - precipfractot ) * & |
---|
401 | ( 1. - MAX( cldfra(i), precipfraccld(i) ) ) & |
---|
402 | / ( 1. - MIN( precipfraccld(i), 1. - eps ) ) |
---|
403 | |
---|
404 | |
---|
405 | !--precipfraccld(i) is here the cloud fraction of the layer above |
---|
406 | dcldfra = cldfra(i) - precipfraccld(i) |
---|
407 | !--Tendency of the clear-sky precipitation fraction. We add a MAX on the |
---|
408 | !--calculation of the current CS precip. frac. |
---|
409 | !dprecipfracclr = MAX( 0., ( precipfractot - cldfra(i) ) ) - precipfracclr(i) |
---|
410 | !--We remove it, because precipfractot is guaranteed to be > cldfra (the MAX is activated |
---|
411 | !--if precipfractot < cldfra) |
---|
412 | dprecipfracclr = ( precipfractot - cldfra(i) ) - precipfracclr(i) |
---|
413 | !--Tendency of the cloudy precipitation fraction. We add a MAX on the |
---|
414 | !--calculation of the current CS precip. frac. |
---|
415 | !dprecipfraccld = MAX( dcldfra , - precipfraccld(i) ) |
---|
416 | !--We remove it, because cldfra is guaranteed to be > 0 (the MAX is activated |
---|
417 | !--if cldfra < 0) |
---|
418 | dprecipfraccld = dcldfra |
---|
419 | |
---|
420 | |
---|
421 | !--If the cloud extends |
---|
422 | IF ( dprecipfraccld .GT. 0. ) THEN |
---|
423 | !--If there is no CS precip, nothing happens. |
---|
424 | !--If there is, we reattribute some of the CS precip flux |
---|
425 | !--to the cloud precip flux, proportionnally to the |
---|
426 | !--decrease of the CS precip fraction |
---|
427 | IF ( precipfracclr(i) .LE. 0. ) THEN |
---|
428 | drainclr = 0. |
---|
429 | dsnowclr = 0. |
---|
430 | ELSE |
---|
431 | drainclr = dprecipfracclr / precipfracclr(i) * rainclr(i) |
---|
432 | dsnowclr = dprecipfracclr / precipfracclr(i) * snowclr(i) |
---|
433 | ENDIF |
---|
434 | !--If the cloud narrows |
---|
435 | ELSEIF ( dprecipfraccld .LT. 0. ) THEN |
---|
436 | !--We reattribute some of the cloudy precip flux |
---|
437 | !--to the CS precip flux, proportionnally to the |
---|
438 | !--decrease of the cloud precip fraction |
---|
439 | draincld = dprecipfraccld / precipfraccld(i) * raincld(i) |
---|
440 | dsnowcld = dprecipfraccld / precipfraccld(i) * snowcld(i) |
---|
441 | drainclr = - draincld |
---|
442 | dsnowclr = - dsnowcld |
---|
443 | !--If the cloud stays the same or if there is no cloud above and |
---|
444 | !--in the current layer, nothing happens |
---|
445 | ELSE |
---|
446 | drainclr = 0. |
---|
447 | dsnowclr = 0. |
---|
448 | ENDIF |
---|
449 | |
---|
450 | !--We add the tendencies |
---|
451 | precipfraccld(i) = precipfraccld(i) + dprecipfraccld |
---|
452 | precipfracclr(i) = precipfracclr(i) + dprecipfracclr |
---|
453 | rainclr(i) = rainclr(i) + drainclr |
---|
454 | snowclr(i) = snowclr(i) + dsnowclr |
---|
455 | raincld(i) = raincld(i) - drainclr |
---|
456 | snowcld(i) = snowcld(i) - dsnowclr |
---|
457 | |
---|
458 | |
---|
459 | !--If vertical heterogeneity is taken into account, we use |
---|
460 | !--the "true" volume fraction instead of a modified |
---|
461 | !--surface fraction (which is larger and artificially |
---|
462 | !--reduces the in-cloud water). |
---|
463 | IF ( ( iflag_cloudth_vert .GE. 3 ) .AND. ( iflag_rain_incloud_vol .EQ. 1 ) ) THEN |
---|
464 | eff_cldfra = ctot_vol(i) |
---|
465 | ELSE |
---|
466 | eff_cldfra = cldfra(i) |
---|
467 | ENDIF |
---|
468 | |
---|
469 | |
---|
470 | !--Start precipitation growth processes |
---|
471 | |
---|
472 | !--If the cloud is big enough, the precipitation processes activate |
---|
473 | IF ( cldfra(i) .GE. seuil_neb ) THEN |
---|
474 | |
---|
475 | !--------------------------------------------------------- |
---|
476 | !-- COLLECTION AND AGGREGATION |
---|
477 | !--------------------------------------------------------- |
---|
478 | !--Collection: processus through which rain collects small liquid droplets |
---|
479 | !--in suspension, and add it to the rain flux |
---|
480 | !--Aggregation: same for snow (precip flux) and ice crystals (in suspension) |
---|
481 | !--Those processes are treated before autoconversion because we do not |
---|
482 | !--want to collect/aggregate the newly formed fluxes, which already |
---|
483 | !--"saw" the cloud as they come from it |
---|
484 | !--The formulas come from Muench and Lohmann 2020 |
---|
485 | |
---|
486 | !--gamma_col: tuning coefficient [-] |
---|
487 | !--rho_rain: volumic mass of rain [kg/m3] |
---|
488 | !--r_rain: size of the rain droplets [m] |
---|
489 | !--Eff_rain_liq: efficiency of the collection process [-] (between 0 and 1) |
---|
490 | !--dqlcol is a gridbox-mean quantity, as is qliq and raincld. They are |
---|
491 | !--divided by respectively eff_cldfra, eff_cldfra and precipfraccld to |
---|
492 | !--get in-cloud mean quantities. The two divisions by eff_cldfra are |
---|
493 | !--then simplified. |
---|
494 | |
---|
495 | !--The sticking efficacy is perfect. |
---|
496 | Eff_rain_liq = 1. |
---|
497 | coef_col = gamma_col * 3. / 4. / rho_rain / r_rain * Eff_rain_liq |
---|
498 | IF ((raincld(i) .GT. 0.) .AND. (coef_col .GT. 0.)) THEN |
---|
499 | !-- ATTENTION Double implicit version |
---|
500 | !-- BEWARE the formule below is FALSE (because raincld is a flux, not a delta flux) |
---|
501 | !qrain_tmp = raincld(i) / hum_to_flux(i) |
---|
502 | !coef_tmp = coef_col * dtime * ( qrain_tmp / precipfraccld(i) + qliq(i) / eff_cldfra ) |
---|
503 | !dqlcol = qliq(i) * ( 1. / ( 1. + 0.5 * ( coef_tmp - 1. + SQRT( & |
---|
504 | ! ( 1. - coef_tmp )**2. + 4. * coef_col * dtime * qrain_tmp / precipfraccld(i) ) & |
---|
505 | ! ) ) - 1. ) |
---|
506 | !--Barriers so that the processes do not consume more liquid/ice than |
---|
507 | !--available. |
---|
508 | !dqlcol = MAX( - qliq(i), dqlcol ) |
---|
509 | !--Exact explicit version, which does not need a barrier because of |
---|
510 | !--the exponential decrease |
---|
511 | dqlcol = qliq(i) * ( EXP( - dtime * coef_col * raincld(i) / precipfraccld(i) ) - 1. ) |
---|
512 | |
---|
513 | !--Add tendencies |
---|
514 | qliq(i) = qliq(i) + dqlcol |
---|
515 | raincld(i) = raincld(i) - dqlcol * hum_to_flux(i) |
---|
516 | |
---|
517 | !--Diagnostic tendencies |
---|
518 | dqrcol(i) = - dqlcol / dtime |
---|
519 | ENDIF |
---|
520 | |
---|
521 | !--Same as for aggregation |
---|
522 | !--Eff_snow_liq formula: following Milbrandt and Yau 2005, |
---|
523 | !--it s a product of a collection efficiency and a sticking efficiency |
---|
524 | Eff_snow_ice = 0.05 * EXP( 0.1 * ( temp(i) - RTT ) ) |
---|
525 | coef_agg = gamma_agg * 3. / 4. / rho_snow / r_snow * Eff_snow_ice |
---|
526 | IF ((snowcld(i) .GT. 0.) .AND. (coef_agg .GT. 0.)) THEN |
---|
527 | !-- ATTENTION Double implicit version? |
---|
528 | !--Barriers so that the processes do not consume more liquid/ice than |
---|
529 | !--available. |
---|
530 | !dqiagg = MAX( - qice(i), dqiagg ) |
---|
531 | !--Exact explicit version, which does not need a barrier because of |
---|
532 | !--the exponential decrease |
---|
533 | dqiagg = qice(i) * ( EXP( - dtime * coef_agg * snowcld(i) / precipfraccld(i) ) - 1. ) |
---|
534 | |
---|
535 | !--Add tendencies |
---|
536 | qice(i) = qice(i) + dqiagg |
---|
537 | snowcld(i) = snowcld(i) - dqiagg * hum_to_flux(i) |
---|
538 | |
---|
539 | !--Diagnostic tendencies |
---|
540 | dqsagg(i) = - dqiagg / dtime |
---|
541 | ENDIF |
---|
542 | |
---|
543 | |
---|
544 | !--------------------------------------------------------- |
---|
545 | !-- AUTOCONVERSION |
---|
546 | !--------------------------------------------------------- |
---|
547 | !--Autoconversion converts liquid droplets/ice crystals into |
---|
548 | !--rain drops/snowflakes. It relies on the formulations by |
---|
549 | !--Sundqvist 1978. |
---|
550 | |
---|
551 | !--If we are in a convective point, we have different parameters |
---|
552 | !--for the autoconversion |
---|
553 | IF ( ptconv(i) ) THEN |
---|
554 | qthresh_auto_rain = cld_lc_con |
---|
555 | qthresh_auto_snow = cld_lc_con_snow |
---|
556 | |
---|
557 | tau_auto_rain = cld_tau_con |
---|
558 | !--tau for snow depends on the ice fraction in mixed-phase clouds |
---|
559 | tau_auto_snow = tau_auto_snow_max & |
---|
560 | + ( tau_auto_snow_min - tau_auto_snow_max ) * ( 1. - icefrac(i) ) |
---|
561 | |
---|
562 | expo_auto_rain = cld_expo_con |
---|
563 | expo_auto_snow = cld_expo_con |
---|
564 | ELSE |
---|
565 | qthresh_auto_rain = cld_lc_lsc |
---|
566 | qthresh_auto_snow = cld_lc_lsc_snow |
---|
567 | |
---|
568 | tau_auto_rain = cld_tau_lsc |
---|
569 | !--tau for snow depends on the ice fraction in mixed-phase clouds |
---|
570 | tau_auto_snow = tau_auto_snow_max & |
---|
571 | + ( tau_auto_snow_min - tau_auto_snow_max ) * ( 1. - icefrac(i) ) |
---|
572 | |
---|
573 | expo_auto_rain = cld_expo_lsc |
---|
574 | expo_auto_snow = cld_expo_lsc |
---|
575 | ENDIF |
---|
576 | |
---|
577 | |
---|
578 | ! Liquid water quantity to remove according to (Sundqvist, 1978) |
---|
579 | ! dqliq/dt = -qliq/tau * ( 1-exp(-(qliqincld/qthresh)**2) ) |
---|
580 | ! |
---|
581 | !--And same formula for ice |
---|
582 | ! |
---|
583 | !--We first treat the second term (with exponential) in an explicit way |
---|
584 | !--and then treat the first term (-q/tau) in an exact way |
---|
585 | |
---|
586 | dqlauto = - qliq(i) * ( 1. - exp( - dtime / tau_auto_rain * ( 1. - exp( & |
---|
587 | - ( qliq(i) / eff_cldfra / qthresh_auto_rain ) ** expo_auto_rain ) ) ) ) |
---|
588 | |
---|
589 | dqiauto = - qice(i) * ( 1. - exp( - dtime / tau_auto_snow * ( 1. - exp( & |
---|
590 | - ( qice(i) / eff_cldfra / qthresh_auto_snow ) ** expo_auto_snow ) ) ) ) |
---|
591 | |
---|
592 | |
---|
593 | !--Barriers so that we don t create more rain/snow |
---|
594 | !--than there is liquid/ice |
---|
595 | dqlauto = MAX( - qliq(i), dqlauto ) |
---|
596 | dqiauto = MAX( - qice(i), dqiauto ) |
---|
597 | |
---|
598 | !--Add tendencies |
---|
599 | qliq(i) = qliq(i) + dqlauto |
---|
600 | qice(i) = qice(i) + dqiauto |
---|
601 | raincld(i) = raincld(i) - dqlauto * hum_to_flux(i) |
---|
602 | snowcld(i) = snowcld(i) - dqiauto * hum_to_flux(i) |
---|
603 | |
---|
604 | !--Diagnostic tendencies |
---|
605 | dqsauto(i) = - dqiauto / dtime |
---|
606 | dqrauto(i) = - dqlauto / dtime |
---|
607 | |
---|
608 | |
---|
609 | !--------------------------------------------------------- |
---|
610 | !-- RIMING |
---|
611 | !--------------------------------------------------------- |
---|
612 | !--Process which converts liquid droplets in suspension into |
---|
613 | !--snow (graupel in fact) because of the collision between |
---|
614 | !--those and falling snowflakes. |
---|
615 | !--The formula comes from Muench and Lohmann 2020 |
---|
616 | !--NB.: this process needs a temperature adjustment |
---|
617 | |
---|
618 | !--Eff_snow_liq formula: following Seifert and Beheng 2006, |
---|
619 | !--assuming a cloud droplet diameter of 20 microns. |
---|
620 | Eff_snow_liq = 0.2 |
---|
621 | coef_rim = gamma_rim * 3. / 4. / rho_snow / r_snow * Eff_snow_liq |
---|
622 | IF ((snowcld(i) .GT. 0.) .AND. (coef_rim .GT. 0.)) THEN |
---|
623 | !-- ATTENTION Double implicit version? |
---|
624 | !--Barriers so that the processes do not consume more liquid than |
---|
625 | !--available. |
---|
626 | !dqlrim = MAX( - qliq(i), dqlrim ) |
---|
627 | !--Exact version, which does not need a barrier because of |
---|
628 | !--the exponential decrease |
---|
629 | dqlrim = qliq(i) * ( EXP( - dtime * coef_col * snowcld(i) / precipfraccld(i) ) - 1. ) |
---|
630 | |
---|
631 | !--Add tendencies |
---|
632 | qliq(i) = qliq(i) + dqlrim |
---|
633 | snowcld(i) = snowcld(i) - dqlrim * hum_to_flux(i) |
---|
634 | |
---|
635 | !--Temperature adjustment with the release of latent |
---|
636 | !--heat because of solid condensation |
---|
637 | temp(i) = temp(i) - dqlrim * RLMLT / RCPD & |
---|
638 | / ( 1. + RVTMP2 * qtot(i) ) |
---|
639 | |
---|
640 | !--Diagnostic tendencies |
---|
641 | dqsrim(i) = - dqlrim / dtime |
---|
642 | ENDIF |
---|
643 | |
---|
644 | ENDIF ! cldfra .GE. seuil_neb |
---|
645 | |
---|
646 | ENDDO ! loop on klon |
---|
647 | |
---|
648 | |
---|
649 | !--Re-calculation of saturation specific humidity |
---|
650 | !--because riming changed temperature |
---|
651 | CALL calc_qsat_ecmwf(klon, temp, qzero, pplay, RTT, 0, .FALSE., qsat, dqsat) |
---|
652 | |
---|
653 | DO i = 1, klon |
---|
654 | |
---|
655 | !--------------------------------------------------------- |
---|
656 | !-- MELTING |
---|
657 | !--------------------------------------------------------- |
---|
658 | !--Process through which snow melts into rain. |
---|
659 | !--The formula is homemade. |
---|
660 | !--NB.: this process needs a temperature adjustment |
---|
661 | |
---|
662 | !--dqsmelt_max: maximum snow melting so that temperature |
---|
663 | !-- stays higher than 273 K [kg/kg] |
---|
664 | !--capa_snowflake: capacitance of a snowflake, equal to |
---|
665 | !-- the radius if the snowflake is a sphere [m] |
---|
666 | !--temp_wetbulb: wet-bulb temperature [K] |
---|
667 | !--snow_fallspeed: snow fall velocity (in clear/cloudy sky) [m/s] |
---|
668 | !--air_thermal_conduct: thermal conductivity of the air [J/m/K/s] |
---|
669 | !--coef_ventil: ventilation coefficient [-] |
---|
670 | !--nb_snowflake: number of snowflakes (in clear/cloudy air) [-] |
---|
671 | |
---|
672 | IF ( ( snowclr(i) + snowcld(i) ) .GT. 0. ) THEN |
---|
673 | !--Computed according to |
---|
674 | !--Cpdry * Delta T * (1 + (Cpvap/Cpdry - 1) * qtot) = Lfusion * Delta q |
---|
675 | dqsmelt_max = MIN(0., ( RTT - temp(i) ) / RLMLT * RCPD & |
---|
676 | * ( 1. + RVTMP2 * qtot(i) )) |
---|
677 | |
---|
678 | !--Initialisation |
---|
679 | dqsclrmelt = 0. |
---|
680 | dqscldmelt = 0. |
---|
681 | |
---|
682 | capa_snowflake = r_snow |
---|
683 | ! ATTENTION POUR L'INSTANT C'EST UN WBULB SELON FORMULE ECMWF |
---|
684 | ! ATTENTION EST-CE QVAP ????? |
---|
685 | temp_wetbulb = temp(i) - ( qsat(i) - qvap(i) ) & |
---|
686 | * ( 1329.31 + 0.0074615 * ( pplay(i) - 0.85e5 ) & |
---|
687 | - 40.637 * ( temp(i) - 275. ) ) |
---|
688 | |
---|
689 | !--In clear air |
---|
690 | IF ( snowclr(i) .GT. 0. ) THEN |
---|
691 | !--Calculated according to |
---|
692 | !-- flux = velocity_snowflakes * nb_snowflakes * volume_snowflakes * rho_snow |
---|
693 | nb_snowflake_clr = snowclr(i) / precipfracclr(i) / snow_fallspeed_clr & |
---|
694 | / ( 4. / 3. * RPI * r_snow**3. * rho_snow ) |
---|
695 | dqsclrmelt = - nb_snowflake_clr * 4. * RPI * air_thermal_conduct & |
---|
696 | * capa_snowflake / RLMLT * coef_ventil & |
---|
697 | * MAX(0., temp_wetbulb - RTT) * dtime |
---|
698 | |
---|
699 | !--Barrier to limit the melting flux to the clr snow flux in the mesh |
---|
700 | dqsclrmelt = MAX( dqsclrmelt , -snowclr(i) / hum_to_flux(i)) |
---|
701 | ENDIF |
---|
702 | |
---|
703 | !--In cloudy air |
---|
704 | IF ( snowcld(i) .GT. 0. ) THEN |
---|
705 | !--Calculated according to |
---|
706 | !-- flux = velocity_snowflakes * nb_snowflakes * volume_snowflakes * rho_snow |
---|
707 | nb_snowflake_cld = snowcld(i) / precipfraccld(i) / snow_fallspeed_cld & |
---|
708 | / ( 4. / 3. * RPI * r_snow**3. * rho_snow ) |
---|
709 | dqscldmelt = - nb_snowflake_cld * 4. * RPI * air_thermal_conduct & |
---|
710 | * capa_snowflake / RLMLT * coef_ventil & |
---|
711 | * MAX(0., temp_wetbulb - RTT) * dtime |
---|
712 | |
---|
713 | !--Barrier to limit the melting flux to the cld snow flux in the mesh |
---|
714 | dqscldmelt = MAX( dqscldmelt , -snowcld(i) / hum_to_flux(i)) |
---|
715 | ENDIF |
---|
716 | |
---|
717 | !--Barrier on temperature. If the total melting flux leads to a |
---|
718 | !--positive temperature, it is limited to keep temperature above 0 degC. |
---|
719 | !--It is activated if the total is LOWER than the max |
---|
720 | !--because everything is negative |
---|
721 | dqstotmelt = dqsclrmelt + dqscldmelt |
---|
722 | IF ( dqstotmelt .LT. dqsmelt_max ) THEN |
---|
723 | !--We redistribute the max melted snow keeping |
---|
724 | !--the clear/cloud partition of the melted snow |
---|
725 | dqsclrmelt = dqsmelt_max * dqsclrmelt / dqstotmelt |
---|
726 | dqscldmelt = dqsmelt_max * dqscldmelt / dqstotmelt |
---|
727 | dqstotmelt = dqsmelt_max |
---|
728 | ENDIF |
---|
729 | |
---|
730 | !--Add tendencies |
---|
731 | rainclr(i) = rainclr(i) - dqsclrmelt * hum_to_flux(i) |
---|
732 | raincld(i) = raincld(i) - dqscldmelt * hum_to_flux(i) |
---|
733 | snowclr(i) = snowclr(i) + dqsclrmelt * hum_to_flux(i) |
---|
734 | snowcld(i) = snowcld(i) + dqscldmelt * hum_to_flux(i) |
---|
735 | |
---|
736 | !--Temperature adjustment with the release of latent |
---|
737 | !--heat because of melting |
---|
738 | temp(i) = temp(i) + dqstotmelt * RLMLT / RCPD & |
---|
739 | / ( 1. + RVTMP2 * qtot(i) ) |
---|
740 | |
---|
741 | !--Diagnostic tendencies |
---|
742 | dqrmelt(i) = - dqstotmelt / dtime |
---|
743 | dqsmelt(i) = dqstotmelt / dtime |
---|
744 | |
---|
745 | ENDIF |
---|
746 | |
---|
747 | |
---|
748 | !--------------------------------------------------------- |
---|
749 | !-- FREEZING |
---|
750 | !--------------------------------------------------------- |
---|
751 | !--Process through which rain freezes into snow. This is |
---|
752 | !--parameterized as an exponential decrease of the rain |
---|
753 | !--water content. |
---|
754 | !--The formula is homemade. |
---|
755 | !--This is based on a caracteritic time of freezing, which |
---|
756 | !--exponentially depends on temperature so that it is |
---|
757 | !--equal to 1 for temp_nowater (see below) and is close to |
---|
758 | !--0 for RTT (=273.15 K). |
---|
759 | !--NB.: this process needs a temperature adjustment |
---|
760 | |
---|
761 | !--dqrfreez_max: maximum rain freezing so that temperature |
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762 | !-- stays lower than 273 K [kg/kg] |
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763 | !--tau_freez: caracteristic time of freezing [s] |
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764 | !--gamma_freez: tuning parameter [s-1] |
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765 | !--alpha_freez: tuning parameter for the shape of the exponential curve [-] |
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766 | !--temp_nowater: temperature below which no liquid water exists [K] (about -40 degC) |
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767 | |
---|
768 | IF ( ( rainclr(i) + raincld(i) ) .GT. 0. ) THEN |
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769 | |
---|
770 | !--Computed according to |
---|
771 | !--Cpdry * Delta T * (1 + (Cpvap/Cpdry - 1) * qtot) = Lfusion * Delta q |
---|
772 | dqrfreez_max = MIN(0., ( temp(i) - RTT ) / RLMLT * RCPD & |
---|
773 | * ( 1. + RVTMP2 * qtot(i) )) |
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774 | |
---|
775 | tau_freez = 1. / ( beta_freez & |
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776 | * EXP( - alpha_freez * ( temp(i) - temp_nowater ) / ( RTT - temp_nowater ) ) ) |
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777 | |
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778 | !--Initialisation |
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779 | dqrclrfreez = 0. |
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780 | dqrcldfreez = 0. |
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781 | |
---|
782 | !--In clear air |
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783 | IF ( rainclr(i) .GT. 0. ) THEN |
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784 | !--Exact solution of dqrain/dt = -qrain/tau_freez |
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785 | dqrclrfreez = rainclr(i) / hum_to_flux(i) * ( EXP( - dtime / tau_freez ) - 1. ) |
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786 | ENDIF |
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787 | |
---|
788 | !--In cloudy air |
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789 | IF ( raincld(i) .GT. 0. ) THEN |
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790 | !--Exact solution of dqrain/dt = -qrain/tau_freez |
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791 | dqrcldfreez = raincld(i) / hum_to_flux(i) * ( EXP( - dtime / tau_freez ) - 1. ) |
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792 | |
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793 | !--------------------------------------------------------- |
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794 | !-- FREEZING OF RAIN WITH CONTACT OF ICE CRYSTALS |
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795 | !--------------------------------------------------------- |
---|
796 | !--Sub-process of freezing which quantifies the collision between |
---|
797 | !--ice crystals in suspension and falling rain droplets. |
---|
798 | !--The rain droplets freeze, becoming graupel, and carrying |
---|
799 | !--the ice crystal (which acted as an ice nucleating particle). |
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800 | !--The formula is adapted from the riming formula. |
---|
801 | |
---|
802 | !--The sticking efficacy is perfect. |
---|
803 | Eff_rain_ice = 1. |
---|
804 | coef_freez = gamma_freez * 3. / 4. / rho_rain / r_rain * Eff_rain_ice |
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805 | !-- ATTENTION Double implicit version? + barriers if needed |
---|
806 | !--Exact version, which does not need a barrier because of |
---|
807 | !--the exponential decrease |
---|
808 | dqifreez = qice(i) * ( EXP( - dtime * coef_freez * raincld(i) / precipfraccld(i) ) - 1. ) |
---|
809 | |
---|
810 | !--We add the two freezing processes in cloud |
---|
811 | dqrcldfreez = dqrcldfreez - dqifreez |
---|
812 | ENDIF |
---|
813 | |
---|
814 | !--Barriers |
---|
815 | !--It is activated if the total is LOWER than the max |
---|
816 | !--because everything is negative |
---|
817 | dqrtotfreez = dqrclrfreez + dqrcldfreez |
---|
818 | IF ( dqrtotfreez .LT. dqrfreez_max ) THEN |
---|
819 | !--We redistribute the max freezed rain keeping |
---|
820 | !--the clear/cloud partition of the freezing rain |
---|
821 | dqrclrfreez = dqrfreez_max * dqrclrfreez / dqrtotfreez |
---|
822 | dqrcldfreez = dqrfreez_max * dqrcldfreez / dqrtotfreez |
---|
823 | dqrtotfreez = dqrfreez_max |
---|
824 | ENDIF |
---|
825 | |
---|
826 | |
---|
827 | !--Add tendencies |
---|
828 | rainclr(i) = rainclr(i) + dqrclrfreez * hum_to_flux(i) |
---|
829 | raincld(i) = raincld(i) + dqrcldfreez * hum_to_flux(i) |
---|
830 | snowclr(i) = snowclr(i) - dqrclrfreez * hum_to_flux(i) |
---|
831 | snowcld(i) = snowcld(i) - dqrcldfreez * hum_to_flux(i) |
---|
832 | |
---|
833 | !--Temperature adjustment with the uptake of latent |
---|
834 | !--heat because of freezing |
---|
835 | temp(i) = temp(i) - dqrtotfreez * RLMLT / RCPD & |
---|
836 | / ( 1. + RVTMP2 * qtot(i) ) |
---|
837 | |
---|
838 | !--Diagnostic tendencies |
---|
839 | dqrfreez(i) = dqrtotfreez / dtime |
---|
840 | dqsfreez(i) = - dqrtotfreez / dtime |
---|
841 | |
---|
842 | ENDIF |
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843 | |
---|
844 | !--If the local flux of rain+snow in clear/cloudy air is lower than rain_int_min, |
---|
845 | !--we reduce the precipiration fraction in the clear/cloudy air so that the new |
---|
846 | !--local flux of rain+snow is equal to rain_int_min. |
---|
847 | !--Here, rain+snow is the gridbox-mean flux of precip. |
---|
848 | !--Therefore, (rain+snow)/precipfrac is the local flux of precip. |
---|
849 | !--If the local flux of precip is lower than rain_int_min, i.e., |
---|
850 | !-- (rain+snow)/precipfrac < rain_int_min , i.e., |
---|
851 | !-- (rain+snow)/rain_int_min < precipfrac , then we want to reduce |
---|
852 | !--the precip fraction to the equality, i.e., precipfrac = (rain+snow)/rain_int_min. |
---|
853 | !--Note that this is physically different than what is proposed in LTP thesis. |
---|
854 | precipfracclr(i) = MIN( precipfracclr(i), ( rainclr(i) + snowclr(i) ) / rain_int_min ) |
---|
855 | precipfraccld(i) = MIN( precipfraccld(i), ( raincld(i) + snowcld(i) ) / rain_int_min ) |
---|
856 | |
---|
857 | !--Calculate outputs |
---|
858 | rain(i) = rainclr(i) + raincld(i) |
---|
859 | snow(i) = snowclr(i) + snowcld(i) |
---|
860 | |
---|
861 | !--Diagnostics |
---|
862 | !--BEWARE this is indeed a diagnostic: this is an estimation from |
---|
863 | !--the value of the flux at the bottom interface of the mesh and |
---|
864 | !--and assuming an upstream numerical calculation |
---|
865 | !--If ok_radocond_snow is TRUE, then the diagnostic qsnowdiag is |
---|
866 | !--used for computing the total ice water content in the mesh |
---|
867 | !--for radiation only |
---|
868 | qraindiag(i) = ( rainclr(i) / ( pplay(i) / RD / temp(i) ) / rain_fallspeed_clr & |
---|
869 | + raincld(i) / ( pplay(i) / RD / temp(i) ) / rain_fallspeed_cld ) |
---|
870 | qsnowdiag(i) = ( snowclr(i) / ( pplay(i) / RD / temp(i) ) / snow_fallspeed_clr & |
---|
871 | + snowcld(i) / ( pplay(i) / RD / temp(i) ) / snow_fallspeed_cld ) |
---|
872 | |
---|
873 | ENDDO ! loop on klon |
---|
874 | |
---|
875 | END SUBROUTINE poprecip_postcld |
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876 | |
---|
877 | END MODULE lmdz_lscp_poprecip |
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