From 8d67a2c5ef73fa6b7865c97375e0d2cf53e6ab4d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Andr=C3=A9=20Schmidt?= <upwli@student.kit.edu>
Date: Wed, 10 Nov 2021 09:51:56 +0000
Subject: [PATCH] Upload WMM
---
corsika/media/WMM.hpp | 122 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 122 insertions(+)
create mode 100644 corsika/media/WMM.hpp
diff --git a/corsika/media/WMM.hpp b/corsika/media/WMM.hpp
new file mode 100644
index 000000000..9c4a790b9
--- /dev/null
+++ b/corsika/media/WMM.hpp
@@ -0,0 +1,122 @@
+/*
+ * (c) Copyright 2020 CORSIKA Project, corsika-project@lists.kit.edu
+ *
+ * This software is distributed under the terms of the GNU General Public
+ * Licence version 3 (GPL Version 3). See file LICENSE for a full version of
+ * the license.
+ */
+
+#include <boost/math/special_functions/legendre.hpp>
+#include <cmath>
+#include <corsika/framework/core/Logging.hpp>
+#include <corsika/framework/utility/CorsikaData.hpp>
+#include <fstream>
+#include <iostream>
+using namespace std;
+
+double factorial(int n) {
+ double factorial = 1;
+ if (n < 0) {
+ CORSIKA_LOG_ERROR("Factorial of a negative number does not exist.");
+ abort();
+ }
+ else {
+ for(int i = 1; i <= n; ++i) {
+ factorial *= i;
+ }
+ }
+ return factorial;
+}
+
+namespace corsika {
+ MagneticFieldVector get_wmm(const CoordinateSystemPtr Cs, const double year, const LengthType altitude, const double latitude, const double longitude) {
+ if (year < 2020 || year > 2025) {
+ CORSIKA_LOG_ERROR("Year has to be between 2020 and 2025.");
+ abort();
+ }
+ if (altitude < -10_km || altitude > 3000_km) {
+ CORSIKA_LOG_WARN("Altitude should be between -10_km and 3000_km.");
+ }
+ if (latitude < -90 || latitude > 90) {
+ CORSIKA_LOG_ERROR("Latitude has to be between -90 and 90 degree.");
+ abort();
+ } else if (latitude < -82 || latitude > 82) {
+ CORSIKA_LOG_WARN("Latitude is close to the poles.");
+ }
+ if (longitude < -180 || longitude > 180) {
+ CORSIKA_LOG_ERROR("Longitude has to be between -180 and 180 degree.");
+ abort();
+ }
+
+ double lat_geo = latitude * constants::pi / 180;
+ double lon = longitude * constants::pi / 180;
+
+ // Transform into spherical coordinates
+ const LengthType A = 6378137_m;
+ const double f = 1 / 298.257223563;
+ const double e_squared = f * (2 - f);
+ LengthType R_c = A / sqrt(1 - e_squared * pow(sin(lat_geo), 2));
+ LengthType p = (R_c + altitude) * cos(lat_geo);
+ LengthType z = sin(lat_geo) * (altitude + R_c * (1 - e_squared));
+ LengthType r = sqrt(p * p + z * z);
+ double lat_sph = asin(z / r);
+
+ const int length = 90;
+ double epoch, g[length], h[length], g_dot[length], h_dot[length];
+ char model_name[7];
+ char release_date[10];
+ int n[length], m[length];
+ ifstream infile;
+
+ // Read in coefficients
+ boost::filesystem::path const path = corsika::corsika_data("GeoMag/WMM.COF");
+ char mdfile[path.generic_string().size() + 1];
+ strcpy(mdfile, path.generic_string().c_str()); //name and path of model file
+ infile.open(mdfile);
+ // Exit if file opening failed
+ if (!infile.is_open()){
+ CORSIKA_LOG_ERROR("Failed opening WMM.COF.");
+ abort();
+ }
+
+ infile >> epoch >> model_name >> release_date;
+ for (int i = 0; i < length; i++) {
+ infile >> n[i] >> m[i] >> g[i] >> h[i] >> g_dot[i] >> h_dot[i];
+ // Time interpolation
+ g[i] = g[i] + (year - epoch) * g_dot[i];
+ h[i] = h[i] + (year - epoch) * h_dot[i];
+ }
+ infile.close();
+
+ double legendre, next_legendre, derivate_legendre;
+ double magneticfield[3] = {0, 0, 0};
+
+ for (int j = 0; j < length; j++) {
+ // cout << assoc_legendre(n[0], m[0], sin(lat_sph)) << endl;
+ legendre = boost::math::legendre_p(n[j], m[j], sin(lat_sph));
+ next_legendre = boost::math::legendre_p(n[j] + 1, m[j], sin(lat_sph));
+
+ // Schmidt semi-normalization and Condon-Shortley phase term
+ if (m[j] > 0) {
+ legendre *= sqrt(2 * factorial(n[j] - m[j]) / factorial(n[j] + m[j])) * pow(-1, m[j]);
+ next_legendre *= sqrt(2 * factorial(n[j] + 1 - m[j]) / factorial(n[j] + 1 + m[j])) * pow(-1, m[j]);
+ }
+ derivate_legendre = (n[j] + 1) * tan(lat_sph) * legendre - sqrt(pow(n[j] + 1, 2) - pow(m[j], 2)) / cos(lat_sph) * next_legendre;
+
+ magneticfield[0] += pow(constants::EarthRadius::Mean / r, n[j] + 2) * (g[j] * cos(m[j] * lon) + h[j] * sin(m[j] * lon)) * derivate_legendre;
+ magneticfield[1] += pow(constants::EarthRadius::Mean / r, n[j] + 2) * m[j] * (g[j] * sin(m[j] * lon) - h[j] * cos(m[j] * lon)) * legendre;
+ magneticfield[2] += (n[j] + 1) * pow(constants::EarthRadius::Mean / r, n[j] + 2) * (g[j] * cos(m[j] * lon) + h[j] * sin(m[j] * lon)) * legendre;
+ }
+ magneticfield[0] *= -1;
+ magneticfield[1] /= cos(lat_sph);
+ magneticfield[2] *= -1;
+
+ // Transform back into geodetic coordinates
+ double magneticfield_geo[3];
+ magneticfield_geo[0] = magneticfield[0] * cos(lat_sph - lat_geo) - magneticfield[2] * sin(lat_sph - lat_geo);
+ magneticfield_geo[1] = magneticfield[1];
+ magneticfield_geo[2] = magneticfield[0] * sin(lat_sph - lat_geo) + magneticfield[2] * cos(lat_sph - lat_geo);
+
+ return MagneticFieldVector{Cs, magneticfield_geo[0] * 1_nT, magneticfield_geo[1] * 1_nT, magneticfield_geo[2] * -1_nT};
+ }
+}
\ No newline at end of file
--
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