1 | MODULE icethd_pnd |
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2 | !!====================================================================== |
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3 | !! *** MODULE icethd_pnd *** |
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4 | !! sea-ice: Melt ponds on top of sea ice |
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5 | !!====================================================================== |
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6 | !! history : ! 2012 (O. Lecomte) Adaptation from Flocco and Turner |
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7 | !! ! 2017 (M. Vancoppenolle, O. Lecomte, C. Rousset) Implementation |
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8 | !! 4.0 ! 2018 (many people) SI3 [aka Sea Ice cube] |
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9 | !!---------------------------------------------------------------------- |
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10 | #if defined key_si3 |
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11 | !!---------------------------------------------------------------------- |
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12 | !! 'key_si3' : SI3 sea-ice model |
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13 | !!---------------------------------------------------------------------- |
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14 | !! ice_thd_pnd_init : some initialization and namelist read |
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15 | !! ice_thd_pnd : main calling routine |
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16 | !!---------------------------------------------------------------------- |
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17 | USE phycst ! physical constants |
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18 | USE dom_oce ! ocean space and time domain |
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19 | USE ice ! sea-ice: variables |
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20 | USE ice1D ! sea-ice: thermodynamics variables |
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21 | USE icetab ! sea-ice: 1D <==> 2D transformation |
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22 | ! |
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23 | USE in_out_manager ! I/O manager |
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24 | USE lib_mpp ! MPP library |
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25 | USE lib_fortran ! fortran utilities (glob_sum + no signed zero) |
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26 | USE timing ! Timing |
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27 | |
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28 | IMPLICIT NONE |
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29 | PRIVATE |
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30 | |
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31 | PUBLIC ice_thd_pnd_init ! routine called by icestp.F90 |
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32 | PUBLIC ice_thd_pnd ! routine called by icestp.F90 |
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33 | |
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34 | INTEGER :: nice_pnd ! choice of the type of pond scheme |
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35 | ! ! associated indices: |
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36 | INTEGER, PARAMETER :: np_pndNO = 0 ! No pond scheme |
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37 | INTEGER, PARAMETER :: np_pndCST = 1 ! Constant pond scheme |
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38 | INTEGER, PARAMETER :: np_pndH12 = 2 ! Evolutive pond scheme (Holland et al. 2012) |
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39 | |
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40 | !! * Substitutions |
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41 | # include "vectopt_loop_substitute.h90" |
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42 | !!---------------------------------------------------------------------- |
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43 | !! NEMO/ICE 4.0 , NEMO Consortium (2018) |
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44 | !! $Id$ |
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45 | !! Software governed by the CeCILL license (see ./LICENSE) |
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46 | !!---------------------------------------------------------------------- |
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47 | CONTAINS |
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48 | |
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49 | SUBROUTINE ice_thd_pnd |
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50 | !!------------------------------------------------------------------- |
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51 | !! *** ROUTINE ice_thd_pnd *** |
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52 | !! |
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53 | !! ** Purpose : change melt pond fraction |
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54 | !! |
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55 | !! ** Method : brut force |
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56 | !!------------------------------------------------------------------- |
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57 | ! |
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58 | SELECT CASE ( nice_pnd ) |
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59 | ! |
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60 | CASE (np_pndCST) ; CALL pnd_CST !== Constant melt ponds ==! |
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61 | ! |
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62 | CASE (np_pndH12) ; CALL pnd_H12 !== Holland et al 2012 melt ponds ==! |
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63 | ! |
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64 | END SELECT |
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65 | ! |
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66 | END SUBROUTINE ice_thd_pnd |
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67 | |
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68 | |
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69 | SUBROUTINE pnd_CST |
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70 | !!------------------------------------------------------------------- |
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71 | !! *** ROUTINE pnd_CST *** |
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72 | !! |
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73 | !! ** Purpose : Compute melt pond evolution |
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74 | !! |
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75 | !! ** Method : Melt pond fraction and thickness are prescribed |
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76 | !! to non-zero values when t_su = 0C |
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77 | !! |
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78 | !! ** Tunable parameters : pond fraction (rn_apnd), pond depth (rn_hpnd) |
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79 | !! |
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80 | !! ** Note : Coupling with such melt ponds is only radiative |
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81 | !! Advection, ridging, rafting... are bypassed |
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82 | !! |
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83 | !! ** References : Bush, G.W., and Trump, D.J. (2017) |
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84 | !!------------------------------------------------------------------- |
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85 | INTEGER :: ji ! loop indices |
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86 | !!------------------------------------------------------------------- |
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87 | DO ji = 1, npti |
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88 | ! |
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89 | IF( a_i_1d(ji) > 0._wp .AND. t_su_1d(ji) >= rt0 ) THEN |
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90 | a_ip_frac_1d(ji) = rn_apnd |
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91 | h_ip_1d(ji) = rn_hpnd |
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92 | a_ip_1d(ji) = a_ip_frac_1d(ji) * a_i_1d(ji) |
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93 | ELSE |
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94 | a_ip_frac_1d(ji) = 0._wp |
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95 | h_ip_1d(ji) = 0._wp |
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96 | a_ip_1d(ji) = 0._wp |
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97 | ENDIF |
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98 | ! |
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99 | END DO |
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100 | ! |
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101 | END SUBROUTINE pnd_CST |
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102 | |
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103 | |
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104 | SUBROUTINE pnd_H12 |
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105 | !!------------------------------------------------------------------- |
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106 | !! *** ROUTINE pnd_H12 *** |
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107 | !! |
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108 | !! ** Purpose : Compute melt pond evolution |
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109 | !! |
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110 | !! ** Method : Empirical method. A fraction of meltwater is accumulated in ponds |
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111 | !! and sent to ocean when surface is freezing |
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112 | !! |
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113 | !! pond growth: Vp = Vp + dVmelt |
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114 | !! with dVmelt = R/rhow * ( rhoi*dh_i + rhos*dh_s ) * a_i |
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115 | !! pond contraction: Vp = Vp * exp(0.01*MAX(Tp-Tsu,0)/Tp) |
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116 | !! with Tp = -2degC |
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117 | !! |
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118 | !! ** Tunable parameters : (no real expertise yet, ideas?) |
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119 | !! |
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120 | !! ** Note : Stolen from CICE for quick test of the melt pond |
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121 | !! radiation and freshwater interfaces |
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122 | !! Coupling can be radiative AND freshwater |
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123 | !! Advection, ridging, rafting are called |
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124 | !! |
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125 | !! ** References : Holland, M. M. et al (J Clim 2012) |
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126 | !!------------------------------------------------------------------- |
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127 | REAL(wp), PARAMETER :: zrmin = 0.15_wp ! minimum fraction of available meltwater retained for melt ponding |
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128 | REAL(wp), PARAMETER :: zrmax = 0.70_wp ! maximum - - - - - |
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129 | REAL(wp), PARAMETER :: zpnd_aspect = 0.174_wp ! pond aspect ratio |
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130 | REAL(wp), PARAMETER :: zTp = -2._wp ! reference temperature |
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131 | REAL(wp), PARAMETER :: freezing_t = 273.0_wp ! temperature below which refreezing occurs |
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132 | ! |
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133 | REAL(wp) :: zfr_mlt ! fraction of available meltwater retained for melt ponding |
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134 | REAL(wp) :: zdv_mlt ! available meltwater for melt ponding |
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135 | REAL(wp) :: actual_mlt ! actual melt water used to make melt ponds (per m2). |
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136 | ! Need to multiply this by ice area to work on volumes. |
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137 | REAL(wp) :: z1_Tp ! inverse reference temperature |
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138 | REAL(wp) :: z1_rhow ! inverse freshwater density |
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139 | REAL(wp) :: z1_zpnd_aspect ! inverse pond aspect ratio |
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140 | REAL(wp) :: zfac, zdum |
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141 | REAL(wp) :: t_grad ! Temperature deficit for refreezing |
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142 | REAL(wp) :: omega_dt ! Time independent accumulated variables used for freezing |
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143 | REAL(wp) :: lh_ip_end ! Lid thickness at end of timestep (temporary variable) |
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144 | REAL(wp) :: actual_frz ! Amount of melt pond that freezes |
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145 | ! |
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146 | INTEGER :: ji ! loop indices |
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147 | !!------------------------------------------------------------------- |
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148 | z1_rhow = 1._wp / rhow |
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149 | z1_zpnd_aspect = 1._wp / zpnd_aspect |
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150 | z1_Tp = 1._wp / zTp |
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151 | |
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152 | ! Define time-independent field for use in refreezing |
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153 | omega_dt = 2.0_wp * rcnd_i * rdtice / (rLfus * rhow) |
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154 | |
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155 | DO ji = 1, npti |
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156 | |
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157 | IF (to_print(ji) == 10) THEN |
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158 | write(numout,*)'icethd_pnd_start: h_ip_1d(ji), a_ip_frac_1d(ji), a_ip_1d(ji) = ',h_ip_1d(ji), ' ', a_ip_frac_1d(ji), ' ', a_ip_1d(ji) |
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159 | END IF |
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160 | |
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161 | ! !--------------------------------! |
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162 | IF( h_i_1d(ji) < rn_himin) THEN ! Case ice thickness < rn_himin ! |
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163 | ! !--------------------------------! |
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164 | !--- Remove ponds on thin ice |
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165 | a_ip_1d(ji) = 0._wp |
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166 | a_ip_frac_1d(ji) = 0._wp |
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167 | h_ip_1d(ji) = 0._wp |
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168 | lh_ip_1d(ji) = 0._wp |
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169 | ! !--------------------------------! |
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170 | ELSE ! Case ice thickness >= rn_himin ! |
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171 | ! !--------------------------------! |
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172 | v_ip_1d(ji) = h_ip_1d(ji) * a_ip_1d(ji) ! record pond volume at previous time step |
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173 | ! |
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174 | ! available meltwater for melt ponding [m, >0] and fraction |
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175 | zdv_mlt = -( dh_i_sum(ji)*rhoi + dh_s_mlt(ji)*rhos ) * z1_rhow |
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176 | zfr_mlt = zrmin + ( zrmax - zrmin ) * a_i_1d(ji) ! from CICE doc |
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177 | !zfr_mlt = zrmin + zrmax * a_i_1d(ji) ! from Holland paper |
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178 | actual_mlt = zfr_mlt * zdv_mlt |
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179 | ! |
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180 | !--- Pond gowth ---! |
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181 | v_ip_1d(ji) = v_ip_1d(ji) + actual_mlt * a_i_1d(ji) |
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182 | ! |
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183 | !--- Lid shrinking ---! |
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184 | lh_ip_1d(ji) = lh_ip_1d(ji) - actual_mlt |
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185 | ! |
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186 | ! |
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187 | !--- Pond contraction (due to refreezing) ---! |
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188 | IF ( t_su_1d(ji) < freezing_t .AND. v_ip_1d(ji) > 0._wp ) THEN |
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189 | t_grad = freezing_t - t_su_1d(ji) |
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190 | |
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191 | ! The following equation is a rearranged form of: |
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192 | ! lid_thickness_end - lid_thickness_start = rcnd_i * t_grad * rdtice / (0.5*(lid_thickness_end + lid_thickness_start) * rLfus * rhow) |
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193 | ! where: lid_thickness_start = lh_ip_1d(ji) |
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194 | ! lid_thickness_end = lh_ip_end |
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195 | ! omega_dt is a bunch of terms in the equation that do not change |
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196 | ! note the use of rhow instead of rhoi as we are working with volumes and it is easier if the water and ice volumes (for the lid and the pond) are the same |
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197 | ! (have the same density). The lid will eventually remelt anyway so it doesn't matter if we make this simplification. |
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198 | |
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199 | lh_ip_end = SQRT(omega_dt * t_grad + lh_ip_1d(ji)**2) |
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200 | actual_frz = lh_ip_end - lh_ip_1d(ji) |
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201 | |
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202 | ! Pond shrinking |
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203 | v_ip_1d(ji) = v_ip_1d(ji) - actual_frz * a_ip_1d(ji) |
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204 | |
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205 | ! Lid growing |
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206 | lh_ip_1d(ji) = lh_ip_1d(ji) + actual_frz |
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207 | ELSE |
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208 | actual_frz = 0._wp |
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209 | END IF |
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210 | |
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211 | ! melt pond mass flux diagnostic (melt only) |
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212 | zfac = actual_mlt * a_i_1d(ji * rhow * r1_rdtice |
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213 | wfx_pnd_1d(ji) = wfx_pnd_1d(ji) - zfac |
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214 | ! |
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215 | ! adjust ice/snow melting flux to balance melt pond flux (>0) |
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216 | zdum = zfac / ( wfx_snw_sum_1d(ji) + wfx_sum_1d(ji) ) |
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217 | wfx_snw_sum_1d(ji) = wfx_snw_sum_1d(ji) * (1._wp + zdum) |
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218 | wfx_sum_1d(ji) = wfx_sum_1d(ji) * (1._wp + zdum) |
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219 | ! |
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220 | ! Make sure pond volume or lid thickness has not gone negative |
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221 | IF ( v_ip_1d(ji) < 0._wp ) v_ip_1d(ji) = 0._wp |
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222 | IF ( lh_ip_1d(ji) < 0._wp ) lh_ip_1d(ji) = 0._wp |
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223 | ! |
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224 | ! Set new pond area and depth assuming linear relation between h_ip and a_ip_frac |
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225 | ! h_ip = zpnd_aspect * a_ip_frac = zpnd_aspect * a_ip/a_i |
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226 | a_ip_1d(ji) = SQRT( v_ip_1d(ji) * z1_zpnd_aspect * a_i_1d(ji) ) |
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227 | a_ip_frac_1d(ji) = a_ip_1d(ji) / a_i_1d(ji) |
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228 | h_ip_1d(ji) = zpnd_aspect * a_ip_frac_1d(ji) |
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229 | |
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230 | ! If lid thickness is ten times greater than pond thickness then remove pond |
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231 | IF ( lh_ip_1d(ji) > h_ip_1d(ji) * 10._wp ) THEN |
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232 | a_ip_1d(ji) = 0._wp |
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233 | a_ip_frac_1d(ji) = 0._wp |
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234 | h_ip_1d(ji) = 0._wp |
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235 | lh_ip_1d(ji) = 0._wp |
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236 | v_ip_1d(ji) = 0._wp |
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237 | END IF |
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238 | ! |
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239 | ENDIF |
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240 | |
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241 | IF (to_print(ji) == 10) THEN |
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242 | write(numout,*)'icethd_pnd: h_ip_1d(ji), zpnd_aspect, a_ip_frac_1d(ji), a_ip_1d(ji) = ',h_ip_1d(ji), zpnd_aspect, a_ip_frac_1d(ji), a_ip_1d(ji) |
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243 | write(numout,*)'icethd_pnd: a_i_1d(ji), v_ip_1d(ji), t_su_1d(ji), zfr_mlt, zdv_mlt = ',a_i_1d(ji), ' ', v_ip_1d(ji), ' ', t_su_1d(ji), ' ', zfr_mlt, ' ', zdv_mlt |
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244 | write(numout,*)'icethd_pnd: meltt = ', -( dh_i_sum(ji)*rhoi + dh_s_mlt(ji)*rhos ) / rhoi |
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245 | END IF |
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246 | |
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247 | END DO |
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248 | ! |
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249 | END SUBROUTINE pnd_H12 |
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250 | |
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251 | |
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252 | SUBROUTINE ice_thd_pnd_init |
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253 | !!------------------------------------------------------------------- |
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254 | !! *** ROUTINE ice_thd_pnd_init *** |
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255 | !! |
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256 | !! ** Purpose : Physical constants and parameters linked to melt ponds |
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257 | !! over sea ice |
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258 | !! |
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259 | !! ** Method : Read the namthd_pnd namelist and check the melt pond |
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260 | !! parameter values called at the first timestep (nit000) |
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261 | !! |
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262 | !! ** input : Namelist namthd_pnd |
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263 | !!------------------------------------------------------------------- |
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264 | INTEGER :: ios, ioptio ! Local integer |
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265 | !! |
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266 | NAMELIST/namthd_pnd/ ln_pnd_H12, ln_pnd_CST, rn_apnd, rn_hpnd, ln_pnd_alb |
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267 | !!------------------------------------------------------------------- |
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268 | ! |
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269 | REWIND( numnam_ice_ref ) ! Namelist namthd_pnd in reference namelist : Melt Ponds |
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270 | READ ( numnam_ice_ref, namthd_pnd, IOSTAT = ios, ERR = 901) |
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271 | 901 IF( ios /= 0 ) CALL ctl_nam ( ios , 'namthd_pnd in reference namelist', lwp ) |
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272 | REWIND( numnam_ice_cfg ) ! Namelist namthd_pnd in configuration namelist : Melt Ponds |
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273 | READ ( numnam_ice_cfg, namthd_pnd, IOSTAT = ios, ERR = 902 ) |
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274 | 902 IF( ios > 0 ) CALL ctl_nam ( ios , 'namthd_pnd in configuration namelist', lwp ) |
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275 | IF(lwm) WRITE ( numoni, namthd_pnd ) |
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276 | ! |
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277 | IF(lwp) THEN ! control print |
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278 | WRITE(numout,*) |
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279 | WRITE(numout,*) 'ice_thd_pnd_init: ice parameters for melt ponds' |
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280 | WRITE(numout,*) '~~~~~~~~~~~~~~~~' |
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281 | WRITE(numout,*) ' Namelist namicethd_pnd:' |
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282 | WRITE(numout,*) ' Evolutive melt pond fraction and depth (Holland et al 2012) ln_pnd_H12 = ', ln_pnd_H12 |
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283 | WRITE(numout,*) ' Prescribed melt pond fraction and depth ln_pnd_CST = ', ln_pnd_CST |
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284 | WRITE(numout,*) ' Prescribed pond fraction rn_apnd = ', rn_apnd |
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285 | WRITE(numout,*) ' Prescribed pond depth rn_hpnd = ', rn_hpnd |
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286 | WRITE(numout,*) ' Melt ponds affect albedo or not ln_pnd_alb = ', ln_pnd_alb |
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287 | ENDIF |
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288 | ! |
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289 | ! !== set the choice of ice pond scheme ==! |
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290 | ioptio = 0 |
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291 | nice_pnd = np_pndNO |
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292 | IF( ln_pnd_CST ) THEN ; ioptio = ioptio + 1 ; nice_pnd = np_pndCST ; ENDIF |
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293 | IF( ln_pnd_H12 ) THEN ; ioptio = ioptio + 1 ; nice_pnd = np_pndH12 ; ENDIF |
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294 | IF( ioptio > 1 ) CALL ctl_stop( 'ice_thd_pnd_init: choose one and only one pond scheme (ln_pnd_H12 or ln_pnd_CST)' ) |
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295 | ! |
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296 | SELECT CASE( nice_pnd ) |
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297 | CASE( np_pndNO ) |
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298 | IF( ln_pnd_alb ) THEN ; ln_pnd_alb = .FALSE. ; CALL ctl_warn( 'ln_pnd_alb=false when no ponds' ) ; ENDIF |
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299 | END SELECT |
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300 | ! |
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301 | END SUBROUTINE ice_thd_pnd_init |
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302 | |
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303 | #else |
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304 | !!---------------------------------------------------------------------- |
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305 | !! Default option Empty module NO SI3 sea-ice model |
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306 | !!---------------------------------------------------------------------- |
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307 | #endif |
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308 | |
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309 | !!====================================================================== |
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310 | END MODULE icethd_pnd |
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