48 lines
2.4 KiB
Go
48 lines
2.4 KiB
Go
|
package formula
|
||
|
|
|
||
|
|
import "math"
|
||
|
|
|
||
|
|
// ExtinctionComponents V 波段天顶消光系数分量，单位星等/大气质量 / V-band zenith extinction components in magnitudes per airmass.
|
||
|
|
type ExtinctionComponents struct {
|
||
|
|
Rayleigh float64 // 分子散射 / molecular scattering
|
||
|
|
Aerosol float64 // 气溶胶 / aerosol
|
||
|
|
Ozone float64 // 臭氧 / ozone
|
||
|
|
Water float64 // 水汽 / water vapour
|
||
|
|
Total float64 // 四项之和 / sum of the four terms
|
||
|
|
}
|
||
|
|
|
||
|
|
// ExtinctionSchaefer 按 Schaefer 经验模型由气象条件合成 V 波段天顶消光系数 / V-band zenith extinction from weather by Schaefer's empirical model.
|
||
|
|
//
|
||
|
|
// heightM 为测站海拔（米），temperatureC 为气温（°C），relativeHumidity 为相对湿度（百分比，
|
||
|
|
// 须在 (0, 100) 内），latitude 为测站纬度（度），sunRA 为太阳赤经（度，用于季节项）。
|
||
|
|
// Total 可直接作为 basic.HeliacalOptions.ExtinctionCoefficient；输入越界时各分量为 NaN。
|
||
|
|
// heightM is site elevation in metres, temperatureC is air temperature,
|
||
|
|
// relativeHumidity is a percentage in (0, 100), latitude is the site latitude,
|
||
|
|
// and sunRA is the Sun's right ascension in degrees for the seasonal terms.
|
||
|
|
// Total can be used as basic.HeliacalOptions.ExtinctionCoefficient. Out-of-range
|
||
|
|
// inputs yield NaN components.
|
||
|
|
func ExtinctionSchaefer(heightM, temperatureC, relativeHumidity, latitude, sunRA float64) ExtinctionComponents {
|
||
|
|
if !isFinitePhotometry(heightM) || !isFinitePhotometry(temperatureC) || !isFinitePhotometry(relativeHumidity) ||
|
||
|
|
!isFinitePhotometry(latitude) || !isFinitePhotometry(sunRA) ||
|
||
|
|
relativeHumidity <= 0 || relativeHumidity >= 100 || latitude < -90 || latitude > 90 {
|
||
|
|
n := math.NaN()
|
||
|
|
return ExtinctionComponents{n, n, n, n, n}
|
||
|
|
}
|
||
|
|
lat := latitude * math.Pi / 180
|
||
|
|
ra := sunRA * math.Pi / 180
|
||
|
|
hemisphere := 1.0
|
||
|
|
if latitude < 0 {
|
||
|
|
hemisphere = -1
|
||
|
|
}
|
||
|
|
// 标高：分子与水汽 8200 m，气溶胶 1500 m；臭氧层在高空，不随测站海拔变化。
|
||
|
|
components := ExtinctionComponents{
|
||
|
|
Rayleigh: 0.1066 * math.Exp(-heightM/8200),
|
||
|
|
Aerosol: 0.1 * math.Exp(-heightM/1500) * math.Pow(1-0.32/math.Log(relativeHumidity/100), 1.33) *
|
||
|
|
(1 + 0.33*hemisphere*math.Sin(ra)),
|
||
|
|
Ozone: 0.031 * (3 + 0.4*(lat*math.Cos(ra)-math.Cos(3*lat))) / 3,
|
||
|
|
Water: 0.031 * 0.94 * (relativeHumidity / 100) * math.Exp(temperatureC/15) * math.Exp(-heightM/8200),
|
||
|
|
}
|
||
|
|
components.Total = components.Rayleigh + components.Aerosol + components.Ozone + components.Water
|
||
|
|
return components
|
||
|
|
}
|