Changeset 1710

Timestamp:

03/17/10 15:37:26 (14 years ago)

Author:

Max Voronkov

Message:

added the code to calculate dry refractivity of the atmosphere

Location:

trunk/src

Files:

• STAtmosphere.cpp (modified) (1 diff)
• STAtmosphere.h (modified) (2 diffs)

trunk/src/STAtmosphere.cpp

@@ -173 +173 @@
 }
 
+/**
+ * Compute the complex refractivity of the dry components of the atmosphere
+ * (oxygen lines) at the given frequency.
+ * @param[in] freq frequency (Hz)
+ * @param[in] temperature air temperature (K)
+ * @param[in] pDry partial pressure of dry components (Pascals)
+ * @param[in] pVapour partial pressure of water vapour (Pascals)
+ * @return complex refractivity
+ **/
+std::complex<double> STAtmosphere::dryRefractivity(double freq, double temperature, 
+                     double pDry, double pVapour)
+{
+  // the number of parameters per atmospheric line and the number of lines taken into account
+  const size_t nLineParams = 7;
+  const size_t nLines = 48;
+  // actual tabulated values
+  const double lines[nLines][nLineParams] = 
+    {{49.452379,    0.12E-6, 11.830,  8.40E-3, 0.0,  5.60E-3,  1.7},
+     {49.962257,    0.34E-6, 10.720,  8.50E-3, 0.0,  5.60E-3,  1.7},
+     {50.474238,    0.94E-6,  9.690,  8.60E-3, 0.0,  5.60E-3,  1.7},
+     {50.987748,    2.46E-6,  8.690,  8.70E-3, 0.0,  5.50E-3,  1.7},
+     {51.503350,    6.08E-6,  7.740,  8.90E-3, 0.0,  5.60E-3,  1.8},
+     {52.021409,   14.14E-6,  6.840,  9.20E-3, 0.0,  5.50E-3,  1.8},
+     {52.542393,   31.02E-6,  6.000,  9.40E-3, 0.0,  5.70E-3,  1.8},
+     {53.066906,   64.10E-6,  5.220,  9.70E-3, 0.0,  5.30E-3,  1.9},
+     {53.595748,  124.70E-6,  4.480, 10.00E-3, 0.0,  5.40E-3,  1.8},
+     {54.129999,  228.00E-6,  3.810, 10.20E-3, 0.0,  4.80E-3,  2.0},
+     {54.671157,  391.80E-6,  3.190, 10.50E-3, 0.0,  4.80E-3,  1.9},
+     {55.221365,  631.60E-6,  2.620, 10.79E-3, 0.0,  4.17E-3,  2.1},
+     {55.783800,  953.50E-6,  2.115, 11.10E-3, 0.0,  3.75E-3,  2.1},
+     {56.264777,  548.90E-6,  0.010, 16.46E-3, 0.0,  7.74E-3,  0.9},
+     {56.363387, 1344.00E-6,  1.655, 11.44E-3, 0.0,  2.97E-3,  2.3},
+     {56.968180, 1763.00E-6,  1.255, 11.81E-3, 0.0,  2.12E-3,  2.5},
+     {57.612481, 2141.00E-6,  0.910, 12.21E-3, 0.0,  0.94E-3,  3.7},
+     {58.323874, 2386.00E-6,  0.621, 12.66E-3, 0.0, -0.55E-3, -3.1},
+     {58.446589, 1457.00E-6,  0.079, 14.49E-3, 0.0,  5.97E-3,  0.8},
+     {59.164204, 2404.00E-6,  0.386, 13.19E-3, 0.0, -2.44E-3,  0.1},
+     {59.590982, 2112.00E-6,  0.207, 13.60E-3, 0.0,  3.44E-3,  0.5},
+     {60.306057, 2124.00E-6,  0.207, 13.82E-3, 0.0, -4.13E-3,  0.7},
+     {60.434775, 2461.00E-6,  0.386, 12.97E-3, 0.0,  1.32E-3, -1.0},
+     {61.150558, 2504.00E-6,  0.621, 12.48E-3, 0.0, -0.36E-3,  5.8},
+     {61.800152, 2298.00E-6,  0.910, 12.07E-3, 0.0, -1.59E-3,  2.9},
+     {62.411212, 1933.00E-6,  1.255, 11.71E-3, 0.0, -2.66E-3,  2.3},
+     {62.486253, 1517.00E-6,  0.078, 14.68E-3, 0.0, -4.77E-3,  0.9},
+     {62.997974, 1503.00E-6,  1.660, 11.39E-3, 0.0, -3.34E-3,  2.2},
+     {63.568515, 1087.00E-6,  2.110, 11.08E-3, 0.0, -4.17E-3,  2.0},
+     {64.127764,  733.50E-6,  2.620, 10.78E-3, 0.0, -4.48E-3,  2.0},
+     {64.678900,  463.50E-6,  3.190, 10.50E-3, 0.0, -5.10E-3,  1.8},
+     {65.224067,  274.80E-6,  3.810, 10.20E-3, 0.0, -5.10E-3,  1.9},
+     {65.764769,  153.00E-6,  4.480, 10.00E-3, 0.0, -5.70E-3,  1.8},
+     {66.302088,   80.09E-6,  5.220,  9.70E-3, 0.0, -5.50E-3,  1.8},
+     {66.836827,   39.46E-6,  6.000,  9.40E-3, 0.0, -5.90E-3,  1.7},
+     {67.369595,   18.32E-6,  6.840,  9.20E-3, 0.0, -5.60E-3,  1.8},
+     {67.900862,    8.01E-6,  7.740,  8.90E-3, 0.0, -5.80E-3,  1.7},
+     {68.431001,    3.30E-6,  8.690,  8.70E-3, 0.0, -5.70E-3,  1.7},
+     {68.960306,    1.28E-6,  9.690,  8.60E-3, 0.0, -5.60E-3,  1.7},
+     {69.489021,    0.47E-6, 10.720,  8.50E-3, 0.0, -5.60E-3,  1.7},
+     {70.017342,    0.16E-6, 11.830,  8.40E-3, 0.0, -5.60E-3,  1.7},
+     {118.750341,  945.00E-6,  0.000, 15.92E-3, 0.0, -0.44E-3,  0.9},
+     {368.498350,   67.90E-6,  0.020, 19.20E-3, 0.6,  0.00E00,  1.0},
+     {424.763120,  638.00E-6,  0.011, 19.16E-3, 0.6,  0.00E00,  1.0},
+     {487.249370,  235.00E-6,  0.011, 19.20E-3, 0.6,  0.00E00,  1.0},
+     {715.393150,   99.60E-6,  0.089, 18.10E-3, 0.6,  0.00E00,  1.0},
+     {773.838730,  671.00E-6,  0.079, 18.10E-3, 0.6,  0.00E00,  1.0},
+     {834.145330,  180.00E-6,  0.079, 18.10E-3, 0.6,  0.00E00,  1.0}};
+     
+  // convert to the units of Liebe
+  const double theta = 300./temperature;
+  const double kPaPVap = 0.001*pVapour;
+  const double kPaPDry = 0.001*pDry;
+  const double fGHz = freq * 1e-9;
+  
+  // some coefficients
+  const double ap = 1.4e-10*(1-1.2e-5*std::pow(fGHz,1.5));
+  const double gamma0 = 5.6e-3*(kPaPDry + 1.1*kPaPVap)*std::pow(theta,0.8);
+  // initial refractivity
+  std::complex<double> result(2.588*kPaPDry*theta +
+         3.07e-4*(1.0/(1.0+std::pow(fGHz/gamma0,2))-1)*kPaPDry*theta*theta,
+         (2*3.07e-4/(gamma0*(1+std::pow(fGHz/gamma0,2))*(1+std::pow(fGHz/60,2))) + 
+          ap*kPaPDry*std::pow(theta,2.5))*fGHz*kPaPDry*theta*theta);
+  // sum the contributions of all the lines
+  for (size_t l = 0; l < nLines; ++l) {
+       const double S = lines[l][1]*kPaPDry*std::pow(theta,3)*exp(lines[l][2]*(1.-theta));
+       const double gamma = lines[l][3]*(kPaPDry*std::pow(theta,0.8-lines[l][4]) + 1.1*kPaPVap*theta);
+       const double delta = lines[l][5]*kPaPDry*std::pow(theta,lines[l][6]);
+       const double x = (lines[l][0]-fGHz)*(lines[l][0]-fGHz) + gamma*gamma;
+       const double y = (lines[l][0]+fGHz)*(lines[l][0]+fGHz) + gamma*gamma;
+       const double z = (lines[l][0]+gamma*gamma/lines[l][0]);
+       result += std::complex<double> (S*( (z-fGHz)/x + (z+fGHz)/y - 2./lines[l][0] + 
+                                  delta*(1/x-1/y)*gamma*fGHz/lines[l][0]),
+               S*( (1/x+1/y)*gamma*fGHz/lines[l][0] -
+               delta*((lines[l][0]-fGHz)/x + (lines[l][0]+fGHz)/y)*fGHz/lines[l][0]));       
+  }
+  
+  return result;
+}

trunk/src/STAtmosphere.h

@@ -43 +43 @@
 #define STATMOSPHERE_H
 
+// std includes
 #include <vector>
+#include <complex>
 
 namespace asap {
@@ -133 +135 @@
   static double wvSaturationPressure(double temperature);
    
+  /**
+   * Compute the complex refractivity of the dry components of the atmosphere
+   * (oxygen lines) at the given frequency.
+   * @param[in] freq frequency (Hz)
+   * @param[in] temperature air temperature (K)
+   * @param[in] pDry partial pressure of dry components (Pascals)
+   * @param[in] pVapour partial pressure of water vapour (Pascals)
+   * @return complex refractivity
+   **/
+   static std::complex<double> dryRefractivity(double freq, double temperature, 
+                     double pDry, double pVapour);
+   
 private: