1 | //#--------------------------------------------------------------------------- |
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2 | //# STAtmosphere.h: Model of atmospheric opacity |
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3 | //#--------------------------------------------------------------------------- |
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4 | //# Copyright (C) 2004 |
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5 | //# ATNF |
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6 | //# |
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7 | //# The code is based on the Fortran code written by Bob Sault for MIRIAD. |
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8 | //# Converted to C++ by Max Voronkov. This code uses a simple model of the |
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9 | //# atmosphere and Liebe's model (1985) of the complex refractive index of |
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10 | //# air. |
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11 | //# |
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12 | //# The model of the atmosphere is one with an exponential fall-off in |
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13 | //# the water vapour content (scale height of 1540 m) and a temperature lapse |
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14 | //# rate of 6.5 mK/m. Otherwise the atmosphere obeys the ideal gas equation |
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15 | //# and hydrostatic equilibrium. |
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16 | //# |
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17 | //# This program is free software; you can redistribute it and/or modify it |
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18 | //# under the terms of the GNU General Public License as published by the Free |
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19 | //# Software Foundation; either version 2 of the License, or (at your option) |
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20 | //# any later version. |
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21 | //# |
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22 | //# This program is distributed in the hope that it will be useful, but |
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23 | //# WITHOUT ANY WARRANTY; without even the implied warranty of |
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24 | //# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General |
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25 | //# Public License for more details. |
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26 | //# |
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27 | //# You should have received a copy of the GNU General Public License along |
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28 | //# with this program; if not, write to the Free Software Foundation, Inc., |
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29 | //# 675 Massachusetts Ave, Cambridge, MA 02139, USA. |
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30 | //# |
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31 | //# Correspondence concerning this software should be addressed as follows: |
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32 | //# Internet email: Malte.Marquarding@csiro.au |
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33 | //# Postal address: Malte Marquarding, |
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34 | //# Australia Telescope National Facility, |
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35 | //# P.O. Box 76, |
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36 | //# Epping, NSW, 2121, |
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37 | //# AUSTRALIA |
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38 | //# |
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39 | //# $Id: STAtmosphere.h 1346 2007-04-26 03:24:41Z mar637 $ |
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40 | //#--------------------------------------------------------------------------- |
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41 | |
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42 | #ifndef STATMOSPHERE_H |
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43 | #define STATMOSPHERE_H |
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44 | |
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45 | #include <vector> |
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46 | |
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47 | namespace asap { |
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48 | |
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49 | /** |
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50 | * This class implements opacity/atmospheric brightness temperature model |
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51 | * equivalent to the model available in MIRIAD. The actual math is a |
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52 | * convertion of the Fortran code written by Bob Sault for MIRIAD. |
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53 | * It implements a simple model of the atmosphere and Liebe's model (1985) |
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54 | * of the complex refractive index of air. |
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55 | * |
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56 | * The model of the atmosphere is one with an exponential fall-off in |
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57 | * the water vapour content (scale height of 1540 m) and a temperature lapse |
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58 | * rate of 6.5 mK/m. Otherwise the atmosphere obeys the ideal gas equation |
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59 | * and hydrostatic equilibrium. |
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60 | * |
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61 | * Note, the model includes atmospheric lines up to 800 GHz, but was not |
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62 | * rigorously tested above 100 GHz and for instruments located at |
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63 | * a significant elevation. For high-elevation sites it may be necessary to |
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64 | * adjust scale height and lapse rate. |
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65 | * |
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66 | * @brief The ASAP atmosphere opacity model |
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67 | * @author Max Voronkov |
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68 | * @date $Date: 2010-03-17 14:55:17 +1000 (Thu, 26 Apr 2007) $ |
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69 | * @version |
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70 | */ |
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71 | class STAtmosphere { |
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72 | public: |
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73 | /** |
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74 | * Default Constructor (apart from optional parameters). |
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75 | * The class set up this way will assume International Standard Atmosphere (ISA) conditions, |
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76 | * except for humidity. The latter is assumed to be 50%, which seems more realistic for |
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77 | * Australian telescopes than 0%. |
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78 | * @param[in] wvScale water vapour scale height (m), default is 1540m to match MIRIAD's model |
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79 | * @param[in] maxAlt maximum altitude of the model atmosphere (m), plane parallel layers are spread linearly up to |
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80 | * this height, default is 10000m to match MIRIAD. |
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81 | * @param[in] nLayers number of plane parallel layers in the model (essentially for a numberical integration), |
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82 | * default is 50 to match MIRIAD. |
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83 | **/ |
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84 | explicit STAtmosphere(double wvScale = 1540., double maxAlt = 10000.0, size_t nLayers = 50); |
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85 | |
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86 | /** |
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87 | * Constructor with explicitly given parameters of the atmosphere |
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88 | * @param[in] temperature air temperature at the observatory (K) |
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89 | * @param[in] pressure air pressure at the observatory (Pascals) |
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90 | * @param[in] humidity air humidity at the observatory (fraction) |
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91 | * @param[in] lapseRate temperature lapse rate (K/m), default is 0.0065 K/m to match MIRIAD and ISA |
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92 | * @param[in] wvScale water vapour scale height (m), default is 1540m to match MIRIAD's model |
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93 | * @param[in] maxAlt maximum altitude of the model atmosphere (m), plane parallel layers are spread linearly up to |
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94 | * this height, default is 10000m to match MIRIAD. |
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95 | * @param[in] nLayers number of plane parallel layers in the model (essentially for a numberical integration), |
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96 | * default is 50 to match MIRIAD. |
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97 | **/ |
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98 | STAtmosphere(double temperature, double pressure, double humidity, double lapseRate = 0.0065, |
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99 | double wvScale = 1540., double maxAlt = 10000.0, size_t nLayers = 50); |
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100 | |
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101 | /** |
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102 | * Set the new weather station data, recompute the model |
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103 | * @param[in] temperature air temperature at the observatory (K) |
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104 | * @param[in] pressure air pressure at the observatory (Pascals) |
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105 | * @param[in] humidity air humidity at the observatory (fraction) |
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106 | **/ |
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107 | void setWeather(double temperature, double pressure, double humidity); |
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108 | |
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109 | protected: |
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110 | /** |
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111 | * Build the atmosphere model based on exponential fall-off, ideal gas and hydrostatic |
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112 | * equilibrium. The model parameters are taken from the data members of this class. |
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113 | **/ |
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114 | void recomputeAtmosphereModel(); |
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115 | |
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116 | /** |
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117 | * Obtain the number of model layers, do consistency check that everything is |
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118 | * resized accordingly |
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119 | * @retrun number of model layers |
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120 | **/ |
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121 | size_t nLayers() const; |
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122 | |
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123 | private: |
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124 | |
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125 | // heights of all model layers |
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126 | std::vector<double> itsHeights; |
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127 | |
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128 | // temperatures of all model layers |
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129 | std::vector<double> itsTemperatures; |
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130 | |
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131 | // partial pressures of dry component for all model layers |
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132 | std::vector<double> itsDryPressures; |
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133 | |
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134 | // partial pressure of water vapour for all model layers |
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135 | std::vector<double> itsVapourPressures; |
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136 | |
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137 | /** |
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138 | * Atmosphere parameters |
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139 | **/ |
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140 | |
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141 | // ground level temperature (K) |
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142 | double itsGndTemperature; |
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143 | |
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144 | // ground level pressure (Pascals) |
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145 | double itsPressure; |
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146 | |
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147 | // ground level humidity (fraction) |
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148 | double itsHumidity; |
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149 | |
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150 | // lapse rate (K/m) |
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151 | double itsLapseRate; |
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152 | |
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153 | // water vapour scale height (m) |
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154 | double itsWVScale; |
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155 | |
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156 | // altitude of the highest layer of the model (m) |
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157 | double itsMaxAlt; |
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158 | }; |
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159 | |
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160 | } // namespace asap |
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161 | |
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162 | #endif // #ifndef STATMOSPHERE_H |
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163 | |
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