1 | MODULE dcmip2016_cyclone_mod |
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2 | |
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3 | !======================================================================= |
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4 | ! |
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5 | ! Date: July 29, 2015 |
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6 | ! |
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7 | ! Function for setting up idealized tropical cyclone initial conditions |
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8 | ! |
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9 | ! SUBROUTINE tropical_cyclone_sample( |
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10 | ! lon,lat,p,z,zcoords,u,v,t,thetav,phis,ps,rho,q) |
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11 | ! |
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12 | ! Given a point specified by: |
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13 | ! lon longitude (radians) |
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14 | ! lat latitude (radians) |
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15 | ! p/z pressure (Pa) / height (m) |
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16 | ! zcoords 1 if z is specified, 0 if p is specified |
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17 | ! |
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18 | ! the functions will return: |
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19 | ! p pressure if z is specified (Pa) |
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20 | ! z geopotential height if p is specified (m) |
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21 | ! u zonal wind (m s^-1) |
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22 | ! v meridional wind (m s^-1) |
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23 | ! t temperature (K) |
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24 | ! thetav virtual potential temperature (K) |
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25 | ! phis surface geopotential (m^2 s^-2) |
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26 | ! ps surface pressure (Pa) |
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27 | ! rho density (kj m^-3) |
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28 | ! q specific humidity (kg/kg) |
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29 | ! |
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30 | ! Initial data are currently identical to: |
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31 | ! |
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32 | ! Reed, K. A., and C. Jablonowski, 2011: An analytic |
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33 | ! vortex initialization technique for idealized tropical |
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34 | ! cyclone studies in AGCMs. Mon. Wea. Rev., 139, 689-710. |
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35 | ! |
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36 | ! Author: Kevin A. Reed |
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37 | ! Stony Brook University |
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38 | ! Email: kevin.a.reed@stonybrook.edu |
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39 | ! |
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40 | !======================================================================= |
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41 | |
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42 | IMPLICIT NONE |
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43 | |
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44 | !======================================================================= |
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45 | ! Physical constants |
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46 | !======================================================================= |
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47 | |
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48 | REAL(8), PARAMETER :: & |
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49 | a = 6371220.0d0, & ! Reference Earth's Radius (m) |
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50 | Rd = 287.0d0, & ! Ideal gas const dry air (J kg^-1 K^1) |
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51 | g = 9.80616d0, & ! Gravity (m s^2) |
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52 | cp = 1004.5d0, & ! Specific heat capacity (J kg^-1 K^1) |
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53 | Lvap = 2.5d6, & ! Latent heat of vaporization of water |
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54 | Rvap = 461.5d0, & ! Ideal gas constnat for water vapor |
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55 | Mvap = 0.608d0, & ! Ratio of molar mass of dry air/water |
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56 | pi = 3.14159265358979d0, & ! pi |
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57 | p0 = 100000.0d0, & ! surface pressure (Pa) |
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58 | kappa = 2.d0/7.d0, & ! Ratio of Rd to cp |
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59 | omega = 7.29212d-5, & ! Reference rotation rate of the Earth (s^-1) |
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60 | deg2rad = pi/180.d0 ! Conversion factor of degrees to radians |
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61 | |
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62 | !======================================================================= |
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63 | ! Test case parameters |
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64 | !======================================================================= |
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65 | REAL(8), PARAMETER :: & |
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66 | rp = 282000.d0, & ! Radius for calculation of PS |
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67 | dp = 1115.d0, & ! Delta P for calculation of PS |
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68 | zp = 7000.d0, & ! Height for calculation of P |
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69 | q0 = 0.021d0, & ! q at surface from Jordan |
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70 | gamma = 0.007d0, & ! lapse rate |
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71 | Ts0 = 302.15d0, & ! Surface temperature (SST) |
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72 | p00 = 101500.d0, & ! global mean surface pressure |
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73 | cen_lat = 10.d0, & ! Center latitude of initial vortex |
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74 | cen_lon = 180.d0, & ! Center longitufe of initial vortex |
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75 | zq1 = 3000.d0, & ! Height 1 for q calculation |
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76 | zq2 = 8000.d0, & ! Height 2 for q calculation |
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77 | exppr = 1.5d0, & ! Exponent for r dependence of p |
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78 | exppz = 2.d0, & ! Exponent for z dependence of p |
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79 | ztrop = 15000.d0, & ! Tropopause Height |
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80 | qtrop = 1.d-11, & ! Tropopause specific humidity |
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81 | rfpi = 1000000.d0, & ! Radius within which to use fixed-point iter. |
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82 | constTv = 0.608d0, & ! Constant for Virtual Temp Conversion |
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83 | deltaz = 2.d-13, & ! Small number to ensure convergence in FPI |
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84 | epsilon = 1.d-25, & ! Small number to aviod dividing by zero in wind calc |
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85 | exponent = Rd*gamma/g, & ! exponent |
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86 | T0 = Ts0*(1.d0+constTv*q0), & ! Surface temp |
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87 | Ttrop = T0 - gamma*ztrop, & ! Tropopause temp |
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88 | ptrop = p00*(Ttrop/T0)**(1.d0/exponent) ! Tropopause pressure |
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89 | |
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90 | CONTAINS |
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91 | |
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92 | !======================================================================= |
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93 | ! Evaluate the tropical cyclone initial conditions |
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94 | !======================================================================= |
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95 | SUBROUTINE tropical_cyclone_test(lon,lat,p,z,zcoords,u,v,t,thetav,phis,ps,rho,q) & |
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96 | BIND(c, name = "tropical_cyclone_test") |
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97 | use iso_c_binding |
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98 | IMPLICIT NONE |
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99 | |
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100 | !------------------------------------------------ |
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101 | ! Input / output parameters |
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102 | !------------------------------------------------ |
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103 | |
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104 | REAL(KIND=C_DOUBLE), INTENT(IN) :: & |
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105 | lon, & ! Longitude (radians) |
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106 | lat ! Latitude (radians) |
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107 | |
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108 | REAL(KIND=C_DOUBLE), INTENT(INOUT) :: & |
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109 | p, & ! Pressure (Pa) |
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110 | z ! Height (m) |
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111 | |
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112 | INTEGER(KIND=C_INT32_T), INTENT(IN) :: zcoords ! 1 if z coordinates are specified |
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113 | ! 0 if p coordinates are specified |
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114 | |
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115 | REAL(KIND=C_DOUBLE), INTENT(OUT) :: & |
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116 | u, & ! Zonal wind (m s^-1) |
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117 | v, & ! Meridional wind (m s^-1) |
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118 | t, & ! Temperature (K) |
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119 | thetav, & ! Virtual potential temperature (K) |
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120 | phis, & ! Surface Geopotential (m^2 s^-2) |
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121 | ps, & ! Surface Pressure (Pa) |
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122 | rho, & ! Density (kg m^-3) |
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123 | q ! Specific Humidity (kg/kg) |
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124 | |
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125 | !------------------------------------------------ |
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126 | ! Local variables |
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127 | !------------------------------------------------ |
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128 | real(8) :: d1, d2, d, vfac, ufac, height, zhere, gr, f, zn |
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129 | |
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130 | integer n |
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131 | |
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132 | !------------------------------------------------ |
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133 | ! Define Great circle distance (gr) and |
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134 | ! Coriolis parameter (f) |
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135 | !------------------------------------------------ |
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136 | f = 2.d0*omega*sin(cen_lat*deg2rad) ! Coriolis parameter |
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137 | gr = a*acos(sin(cen_lat*deg2rad)*sin(lat) + & ! Great circle radius |
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138 | (cos(cen_lat*deg2rad)*cos(lat)*cos(lon-cen_lon*deg2rad))) |
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139 | |
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140 | !------------------------------------------------ |
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141 | ! Initialize PS (surface pressure) |
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142 | !------------------------------------------------ |
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143 | ps = p00-dp*exp(-(gr/rp)**exppr) |
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144 | |
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145 | !------------------------------------------------ |
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146 | ! Initialize altitude (z) if pressure provided |
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147 | ! or pressure if altitude (z) is provided |
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148 | !------------------------------------------------ |
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149 | if (zcoords .eq. 1) then |
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150 | |
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151 | height = z |
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152 | |
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153 | if (height > ztrop) then |
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154 | p = ptrop*exp(-(g*(height-ztrop))/(Rd*Ttrop)) |
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155 | else |
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156 | p = (p00-dp*exp(-(gr/rp)**exppr)*exp(-(height/zp)**exppz)) & |
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157 | * ((T0-gamma*height)/T0)**(1/exponent) |
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158 | end if |
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159 | |
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160 | else |
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161 | |
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162 | height = (T0/gamma)*(1.d0-(p/ps)**exponent) |
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163 | |
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164 | ! If inside a certain distance of the center of the storm |
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165 | ! perform a Fixed-point iteration to calculate the height |
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166 | ! more accurately |
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167 | |
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168 | if (gr < rfpi ) then |
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169 | zhere = height |
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170 | n = 1 |
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171 | 20 continue |
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172 | n = n+1 |
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173 | zn = zhere - fpiF(p,gr,zhere)/fpidFdz(gr,zhere) |
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174 | if (n.gt.20) then |
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175 | PRINT *,'FPI did not converge after 20 interations in q & T!!!' |
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176 | else if ( abs(zn-zhere)/abs(zn) > deltaz) then |
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177 | zhere = zn |
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178 | goto 20 |
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179 | end if |
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180 | height = zn |
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181 | end if |
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182 | end if |
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183 | |
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184 | !------------------------------------------------ |
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185 | ! Initialize U and V (wind components) |
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186 | !------------------------------------------------ |
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187 | d1 = sin(cen_lat*deg2rad)*cos(lat) - & |
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188 | cos(cen_lat*deg2rad)*sin(lat)*cos(lon-cen_lon*deg2rad) |
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189 | d2 = cos(cen_lat*deg2rad)*sin(lon-cen_lon*deg2rad) |
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190 | d = max(epsilon, sqrt(d1**2.d0 + d2**2.d0)) |
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191 | ufac = d1/d |
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192 | vfac = d2/d |
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193 | |
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194 | if (height > ztrop) then |
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195 | u = 0.d0 |
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196 | v = 0.d0 |
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197 | else |
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198 | v = vfac*(-f*gr/2.d0+sqrt((f*gr/2.d0)**(2.d0) & |
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199 | - exppr*(gr/rp)**exppr*Rd*(T0-gamma*height) & |
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200 | /(exppz*height*Rd*(T0-gamma*height)/(g*zp**exppz) & |
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201 | +(1.d0-p00/dp*exp((gr/rp)**exppr)*exp((height/zp)**exppz))))) |
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202 | u = ufac*(-f*gr/2.d0+sqrt((f*gr/2.d0)**(2.d0) & |
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203 | - exppr*(gr/rp)**exppr*Rd*(T0-gamma*height) & |
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204 | /(exppz*height*Rd*(T0-gamma*height)/(g*zp**exppz) & |
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205 | +(1.d0-p00/dp*exp((gr/rp)**exppr)*exp((height/zp)**exppz))))) |
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206 | end if |
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207 | |
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208 | !------------------------------------------------ |
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209 | ! Initialize water vapor mixing ratio (q) |
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210 | !------------------------------------------------ |
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211 | if (height > ztrop) then |
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212 | q = qtrop |
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213 | else |
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214 | q = q0*exp(-height/zq1)*exp(-(height/zq2)**exppz) |
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215 | end if |
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216 | |
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217 | !------------------------------------------------ |
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218 | ! Initialize temperature (T) |
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219 | !------------------------------------------------ |
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220 | if (height > ztrop) then |
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221 | t = Ttrop |
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222 | else |
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223 | t = (T0-gamma*height)/(1.d0+constTv*q)/(1.d0+exppz*Rd*(T0-gamma*height)*height & |
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224 | /(g*zp**exppz*(1.d0-p00/dp*exp((gr/rp)**exppr)*exp((height/zp)**exppz)))) |
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225 | end if |
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226 | |
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227 | !----------------------------------------------------- |
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228 | ! Initialize virtual potential temperature (thetav) |
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229 | !----------------------------------------------------- |
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230 | thetav = t * (1.d0+constTv*q) * (p0/p)**(Rd/cp) |
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231 | |
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232 | !----------------------------------------------------- |
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233 | ! Initialize surface geopotential (PHIS) |
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234 | !----------------------------------------------------- |
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235 | phis = 0.d0 ! constant |
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236 | |
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237 | !----------------------------------------------------- |
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238 | ! Initialize density (rho) |
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239 | !----------------------------------------------------- |
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240 | rho = p/(Rd*t*(1.d0+constTv*q)) |
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241 | |
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242 | END SUBROUTINE tropical_cyclone_test |
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243 | |
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244 | !----------------------------------------------------------------------- |
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245 | ! First function for fixed point iterations |
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246 | !----------------------------------------------------------------------- |
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247 | REAL(8) FUNCTION fpiF(phere, gr, zhere) |
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248 | IMPLICIT NONE |
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249 | REAL(8), INTENT(IN) :: phere, gr, zhere |
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250 | |
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251 | fpiF = phere-(p00-dp*exp(-(gr/rp)**exppr)*exp(-(zhere/zp)**exppz)) & |
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252 | *((T0-gamma*zhere)/T0)**(g/(Rd*gamma)) |
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253 | |
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254 | END FUNCTION fpiF |
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255 | |
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256 | !----------------------------------------------------------------------- |
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257 | ! Second function for fixed point iterations |
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258 | !----------------------------------------------------------------------- |
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259 | REAL(8) FUNCTION fpidFdz(gr, zhere) |
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260 | IMPLICIT NONE |
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261 | REAL(8), INTENT(IN) :: gr, zhere |
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262 | |
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263 | fpidFdz =-exppz*zhere*dp*exp(-(gr/rp)**exppr)*exp(-(zhere/zp)**exppz)/(zp*zp)*((T0-gamma*zhere)/T0)**(g/(Rd*gamma)) & |
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264 | +g/(Rd*T0)*(p00-dp*exp(-(gr/rp)**exppr)*exp(-(zhere/zp)**exppz))*((T0-gamma*zhere)/T0)**(g/(Rd*gamma)-1.d0) |
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265 | |
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266 | END FUNCTION fpidFdz |
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267 | |
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268 | END MODULE dcmip2016_cyclone_mod |
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269 | |
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