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Solar constant
About: Solar constant is a research topic. Over the lifetime, 967 publications have been published within this topic receiving 29647 citations.
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TL;DR: In this article, the properties of the solar constant variability are considered according to the results of satellite observations and wavelet analysis is used to study short-period processes in each solar cycle.
Abstract: The properties of the solar constant variability are considered according to the results of satellite observations (
http://lasp.colorado.edu/home/sorce/data/tsi-data/
). The obtainment of satellite data with an accuracy of 0.01% that is devoid of atmospheric influence allows a detailed analysis of variations in this index of solar activity and space weather for solar-activity cycles 21–24. The use of wavelet analysis demonstrates the properties of the 11-year cycle in the variation of the solar constant. With the exclusion of variations of the 11-year cycle, it is possible to study short-period processes in each solar cycle. The variations in the solar constant demonstrate their own local spectrum of power periods, which differs from the activity periods according to sunspot observations. The most significant decrease in the solar constant occurs during the passage in the center of the solar disk of large groups of spots and activity complexes that block the solar constant. Thus, the basic properties of the intrinsic variability of the solar constant differ from the properties of the magnetic cycle.
25 Aug 2022
TL;DR: In this paper , the SORCESOLSTICE instrument was used with multiple identical channels which are used at various cadence to track degradation differentially, and the benefits of following a constant and regular observation plan to improve the accuracy of the degradation corrections.
Abstract: Solar observations are intrinsically harsh to optics and detectors. Space measurements in particular expose the spacecraft and payload to charged particles and UV radiation which causes changes in the transmission profile of windows and optics. These affect the absolute accuracy of the measurements over time. Astronomical observations typically rely on standard stars and calibration sources to track and correct changes in the instrument. This method was used with the SORCESOLSTICE instrument during its 17 year Solar Spectral Irradiance (SSI) measurement record covering more than 9 orders of magnitudes in brightness between stellar and Solar observations. Other instruments are designed with multiple identical channels which are used at various cadence to track degradation differentially. We present the advantages and issues discovered with each method and the benefits of following a constant and regular observation plan to improve the accuracy of the degradation corrections.
TL;DR: In this article, a tabular form of the daily solar radiation at the outer limit of the earth's atmosphere is presented at intervals of five days for each month of the year.
Abstract: Values of daily solar radiation at the outer limit of the earth’s atmosphere are needed for various applications. Based on the latest value of solar constant, computation of extraterrestrial daily solar insolation on a horizontal surface have been carried out for all the latitudes at an interval of 5 degrees. The calculated values are presented in the tabular form at intervals of five days for each month of the year.
01 Jan 2021
TL;DR: Extraterrestrial solar irradiance (KEX) as mentioned in this paper is defined as the irradiance at the top of the Earth's atmosphere, on a plane perpendicular to the Sun's rays, and at mean Earth-Sun distance.
Abstract: Extraterrestrial solar irradiance (KEX) is the solar irradiance at the “top” of the Earth’s atmosphere, on a plane perpendicular to the Sun’s rays, and at mean Earth–Sun distance. To calculate the amount of irradiance available in the photic zone, the maximum possible extraterrestrial irradiance or the solar constant, which is 1366 + 3 Watts per square meter (or W m−2), is adjusted downward to account for atmospheric attenuation and finally attenuation rates in the water body, as a function of the reciprocal of the inverse square law—the radius vector—the Earth–Sun distance d divided by the mean of d throughout the year, along with the zenith angle (z) formed by the Sun, the surface point of interest, and the vertical. The zenith angle can be computed as a function of the latitude of interest, the latitude experiencing the direct rays of the Sun on that day, i.e., solar declination (δ), and the angle that the Earth has yet to rotate through to reach solar noon or hour angle (h). On a clear day, perhaps 80% of KEX will be transmitted to the surface. However, under heavy clouds, as little as 10% of KEX reaches the surface. When solar radiation strikes a water surface at any angle other than the vertical, refraction occurs because of the density difference between air and water. In oceanography and coastal sciences, modeling the radiation emitted by a point or area source of light (usually the Sun) can often be important. Three-dimensional radiant intensity can be used to derive the amount of energy radiated by and onto points or bodies in the ocean.