GB/T 37835-2019Process for determining solar irradiances (English PDF)

2.1 Astronomical unit

The average distance between the Earth and the Sun, the current accepted value is (149,597,870,691 ± 3) m. See references [1] and references [2].

Note: The distance between objects in the solar system is usually expressed in ua. Ua or AU is a unit of non-international unit system (hereinafter referred to as SI), but in the country In general, this value is obtained experimentally in units of SI. This value is used when describing the motion of objects in the solar system, and the gravitational constant is (0.01720209895) 2ua3·d-2, here one day (1d) = 86400s (see reference [3]).

1AU is slightly less than the average distance between the Earth and the Sun, because AU is based on the point mass of the Kepler elliptical orbital radius, In the unit of 2pi/k orbital period, k is the Gaussian gravitational constant and is (0.01720209895 AU3·d-2) 1/2. Latest published authority The value of 1ua is found in reference [2].

2.2 Solar irradiance

It can be seen that the solar radiation in the sun is expressed by the power per unit area, and the international unit is watts per square meter (W·m-2).

Note: In general, the "visible day" contains all the solar radiation from various regions of the sun, such as the chromosphere, the transition zone and the corona.

Photo. Some users refer to these combined exposures as "visible daylight." A more accurate synonym for solar irradiance is "total solar irradiance" due to spectroscopic Solar radiation is an irradiation consisting of different wavelengths, which can be expressed in SI units W·m-3, or in SI fraction units W·m-2·nm-1 Show. It can also be supplemented by a mixed spectrophotometric solar irradiance unit (eg, quantum number cm-2·s-1·nm-1, photon number cm-2·s-1·A-1 and The grid cm-2·s-1·nm-1), however, the mixed unit cannot be substituted for the SI unit in the report.

This standard does not currently specify solar irradiance or burst energy from a local surface, unless solar irradiance is used for full-day The face (referred to as visible hemisphere) integral representation. In order to calibrate ground-based instruments (solar calorimeters) that measure total solar irradiance, World Gas in 1980 The organization uses the world's radiation measurement benchmark as the main criterion to ensure the worldwide compliance of solar radiation measurements. World radiation measurement The volume reference is established and maintained by the world standard radiometer group using data measured by an absolute cavity radiometer. The world standard radiometer group is located in Rui.

World Radiation Center of the St. Walters Physical Meteorological Observatory. The uncertainty of the world radiation measurement benchmark is 0.3%. In two scales Uncertainty, the world's radiation measurement benchmark is consistent with the measurement of the low temperature radiometer and the radiometric measurement in SI scale (see ginseng)

Test paper [4] and reference [5]). World radiation measurement benchmarks have been used in aerospace, but due to changes in solar constants, the sun often The uncertainty of the number is large, so a non-mandatory spatial absolute radiation benchmark is proposed (see Reference [6]).