package com.dy.pipIrrModel.modelCalculate;
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import net.objecthunter.exp4j.Expression;
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import net.objecthunter.exp4j.ExpressionBuilder;
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/**
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* @Author: liurunyu
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* @Date: 2025/8/18 14:51
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* @Description 哈格里夫斯（Hargreaves）公式 计算作物实际蒸散量（mm/day）
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*/
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public class Hargreaves {
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/**
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* 计算弧度
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* 弧度=角度× π/180
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* @param lat 地理纬度
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* @return
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*/
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public static Double rad(Double lat) {
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Expression expression = new ExpressionBuilder("x * pi / 180")
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.variables("x")
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.build();
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// 设置变量值
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expression.setVariable("x", lat);
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Double result = expression.evaluate();
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return result ;
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}
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/**
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* 太阳磁偏角
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* @param dayIndex 为年内某天的日序数（比如1月1日为1，12月31日为365或366）
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* @return
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*/
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public static Double sunMagnetismAngular(Integer dayIndex){
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Expression expression = new ExpressionBuilder("0.409 * sin(((2 * pi) / 365) * x - 1.39)")
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.variables("x")
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.build();
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// 设置变量值
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expression.setVariable("x", dayIndex);
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Double result = expression.evaluate();
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return result ;
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}
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/**
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* 日地间相对距离的倒数
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* @param dayIndex 为年内某天的日序数（比如1月1日为1，12月31日为365或366）
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* @return
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*/
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public static Double sunEarthDistance(Integer dayIndex){
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Expression expression = new ExpressionBuilder("1 + (0.033 * cos(((2 * pi) / 365) * x))")
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.variables("x")
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.build();
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// 设置变量值
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expression.setVariable("x", dayIndex);
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Double result = expression.evaluate();
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return result ;
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}
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/**
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* 太阳时角
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* 0.409 * sin(2 * pi / 365 * x - 1.39)
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* @param fai 地理弧度
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* @param sunMagnetismAngular 太阳磁偏角
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* @return
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*/
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public static Double sunTimeAngular(Double fai, Double sunMagnetismAngular){
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Expression expression = new ExpressionBuilder("acos(-tan(x) * tan(y))")
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.variables("x", "y")
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.build();
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// 设置变量值
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expression.setVariable("x", fai);
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expression.setVariable("y", sunMagnetismAngular);
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Double result = expression.evaluate();
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return result ;
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}
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/**
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* 计算天顶辐射
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* @param sunEarthDistance 日地间相对距离的倒数
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* @param sunTimeAngular 太阳时偏角
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* @param fai 地理弧度
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* @param sunMagnetismAngular 太阳磁偏角
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* @return
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*/
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public static Double zenithRadiation(Double sunEarthDistance,
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Double sunTimeAngular,
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Double fai,
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Double sunMagnetismAngular){
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Expression expression = new ExpressionBuilder("((24 * 60) / pi) * 0.082 * a * ((b * sin(c) * sin(d)) + (cos(c) * cos(d) * sin(b)))")
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.variables("a", "b", "c", "d")
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.build();
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// 设置变量值
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expression.setVariable("a", sunEarthDistance);
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expression.setVariable("b", sunTimeAngular);
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expression.setVariable("c", fai);
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expression.setVariable("d", sunMagnetismAngular);
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Double result = expression.evaluate();
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return result ;
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}
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/**
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* 格里夫斯（Hargreaves）公式计算作物蒸散量（mm/day）
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* @param kc 作物系数
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* @param maxT 一日内最高温度
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* @param maxT 一日内最高温度
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* @param zenithRadiation 天顶辐射
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* @return
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*/
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public static Double ET0(Double kc, Double maxT, Double minT, Double zenithRadiation){
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Expression expression = new ExpressionBuilder("x * (0.0023 * (((a + b) / 2) + 17.8) * ((a + b)^(1/2)) * c * 0.408)")
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.variables("x", "a", "b", "c")
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.build();
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// 设置变量值
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expression.setVariable("x", kc);
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expression.setVariable("a", maxT);
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expression.setVariable("b", minT);
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expression.setVariable("c", zenithRadiation);
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Double result = expression.evaluate();
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return result ;
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}
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public static void main(String[] args) {
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Double lat = 38.561976140977116 ;
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Integer dayIndex = 180 ;
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Double kc = 0.41 ;//作物系数
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Double maxT = 40.1 ;//一日内最高温度
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Double minT = 40.1 ;//一日内最低温度
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Double fai = rad(lat);
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System.out.println(fai);
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Double sunMagnetismAngular = sunMagnetismAngular(dayIndex);
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System.out.println(sunMagnetismAngular);
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Double sunEarthDistance = sunEarthDistance(dayIndex);
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System.out.println(sunEarthDistance);
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Double sunTimeAngular = sunTimeAngular(fai, sunMagnetismAngular);
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System.out.println(sunTimeAngular);
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Double zenithRadiation = zenithRadiation(sunEarthDistance, sunTimeAngular, fai, sunMagnetismAngular);
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System.out.println(zenithRadiation);
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Double et0 = ET0(kc, maxT, minT, zenithRadiation);
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System.out.println(et0);
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}
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}
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