SolarRadiation.hpp

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// SPDX-License-Identifier: Apache-2.0
//
// Copyright 2026 Caleb Buahin
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

 
#ifndef OPENSWMM_ENGINE_TRANSPORT_SOLAR_RADIATION_HPP
#define OPENSWMM_ENGINE_TRANSPORT_SOLAR_RADIATION_HPP
 
namespace openswmm {
struct SimulationContext;
struct SolarConfig;
struct CloudConfig;
}
 
namespace openswmm::transport::heat {

inline constexpr double kSolarConstant = 1367.0;

inline constexpr double kStdPressureMb = 1013.25;

struct SolarPosition {
    double declination_deg = 0.0;  
    double eq_time_min     = 0.0;  
    double hour_angle_deg  = 0.0;  
    double zenith_deg      = 90.0; 
    double cos_zenith      = 0.0;  
    double elevation_deg   = 0.0;  
    double eccentricity    = 1.0;
};

SolarPosition solarPosition(int day_of_year, double hour_local, double lat_deg,
                            double lon_deg, double tz_hours) noexcept;

double airMass(double zenith_deg) noexcept;

double pressureFromElevation(double elevation_m) noexcept;

double birdClearSkyGHI(const SolarPosition& pos, double pressure_mb,
                       const SolarConfig& cfg) noexcept;

double cloudShortwaveFactor(double cloud_fraction, double k, double n) noexcept;

double cloudLongwaveFactor(double cloud_fraction, double k_lw) noexcept;

void updateSolarForcing(SimulationContext& ctx) noexcept;
 
}  // namespace openswmm::transport::heat
 
#endif  // OPENSWMM_ENGINE_TRANSPORT_SOLAR_RADIATION_HPP