GPT.hpp

Go to the documentation of this file.

// This file is part of INSTINCT, the INS Toolkit for Integrated
// Navigation Concepts and Training by the Institute of Navigation of
// the University of Stuttgart, Germany.
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at https://mozilla.org/MPL/2.0/.
 
/// @file GPT.hpp
/// @brief GPT2/3 (Global Pressure and Temperature) models
/// @author Rui Wang (rui.wang@ins.uni-stuttgart.de)
/// @author T. Topp (topp@ins.uni-stuttgart.de)
/// @date 2023-02-22
/// @note See https://vmf.geo.tuwien.ac.at/codes/ for code sources in matlab.
 
#pragma once
 
#include "Eigen/Dense"
 
namespace NAV
{
/// GPT2 output parameters
struct GPT2output
{
    double p{};    ///< p pressure in [hPa] (vector of length nstat)
    double T{};    ///< temperature in [degrees Celsius] (vector of length nstat)
    double dT{};   ///< temperature lapse rate in [degrees per km] (vector of length nstat)
    double Tm{};   ///< mean temperature of the water vapor in [degrees Kelvin] (vector of length nstat)
    double e{};    ///< water vapor pressure in [hPa] (vector of length nstat)
    double ah{};   ///< hydrostatic mapping function coefficient at zero height (VMF1) (vector of length nstat)
    double aw{};   ///< wet mapping function coefficient (VMF1) (vector of length nstat)
    double la{};   ///< water vapor decrease factor (vector of length nstat)
    double undu{}; ///< geoid undulation in [m] (vector of length nstat)
};
 
/// GPT3 output parameters
struct GPT3output : public GPT2output
{
    double Gn_h{}; ///< hydrostatic north gradient in [m]
    double Ge_h{}; ///< hydrostatic east gradient in [m]
    double Gn_w{}; ///< wet north gradient in [m]
    double Ge_w{}; ///< wet east gradient in [m]
};
 
/// @brief Determine pressure, temperature, temperature lapse rate, mean temperature of the water vapor,
///        water vapor pressure, hydrostatic and wet mapping function coefficients ah and aw, water vapour decrease
///        factor and geoid undulation for specific sites near the Earth surface, based on a 1 x 1 degree GPT2 grid
/// @param[in] mjd modified Julian date
/// @param[in] lla_pos [𝜙, λ, h]^T Geodetic latitude, longitude and height in [rad, rad, m]
/// @note See \cite bohm2015development Böhm2015
GPT2output GPT2_param(const double& mjd, const Eigen::Vector3d& lla_pos);
 
/// @brief Determine pressure, temperature, temperature lapse rate,
///        mean temperature of the water vapor, water vapour pressure, hydrostatic
///        and wet mapping function coefficients ah and aw, water vapour decrease
///        factor, geoid undulation and empirical tropospheric gradients for
///        specific sites near the earth's surface, based on a 1 x 1 degree GPT3 grid
/// @param[in] mjd modified Julian date
/// @param[in] lla_pos [𝜙, λ, h]^T Geodetic latitude, longitude and height in [rad, rad, m]
/// @note See \cite Landskron2018 Landskron2018
GPT3output GPT3_param(const double& mjd, const Eigen::Vector3d& lla_pos);
 
/// @brief To calculate the day of year
/// @param[in] mjd the Modified Julien Date
/// @return the day of year
double mjd2doy(const double& mjd);
 
/// @brief This subroutine determines the zenith wet delay
/// @param[in] e water vapor pressure in hPa
/// @param[in] Tm mean temperature in Kelvin
/// @param[in] la water vapor lapse rate (see definition in Askne and Nordius 1987)
/// @return zwd: zenith wet delay in meter
/// @note See \cite Askne1987 Aske and Nordius (1987), eq. 22
double asknewet(const double& e, const double& Tm, const double& la);
 
} // namespace NAV