Solar constant

About: Solar constant is a research topic. Over the lifetime, 967 publications have been published within this topic receiving 29647 citations.

Radiation Received from Earth by a Synchronous Meteorological Satellite

Abstract: A meteorological satellite capable of providing day-and-night cloud cover information and data on the earth's heat budget is considered to be in a 24-hr synchronous orbit (22,240 miles alt over the equator at 90 °W). A model is developed from which estimates may be made of the radiation incident on the satellite sensors as a function of the surface from which the radiation emanates (geographical position, altitude, reflective characteristics, temperature, etc.) and the surface-sun relationship (solar altitude). Examples are presented for the determination of sensor irradiation in the visible spectral region (0.4 to 0.7 /z) under assumed day-and-night cloud cover conditions. The heat budget problem is considered and an estimate is obtained for the percentage of thermal radiation transmitted through the atmosphere for a given earth blackbody temperature.

General trends in the changes of indices of solar activity in the late xx - early xxi century

Abstract: The analysis of the observations of solar activity indexes SSN (NOAA Sunspot Numbers), the radio flux at a wavelength of 10.7 cm (F10.7) and the solar constant (TSI) during the cycles 22 - 24 is presented. We found a decrease of the observed values of the SSNobs which was calculated with SSNsyn (using regression relationships between SSN and F10.7) after 1990 year on 20 - 25% instead of 35%, as was previously assumed. The changes in characteristics of the most popular index, SSN, such as decrease in the number of sunspots, the reduction of the magnetic field in small and medium-sized spots are not in full compliance with the proposed scenario of solar activity predicted by radio flux F10.7 in the cycles 23 and 24, and cannot be fully explained by the influence on the SSN values of additional minimum of 50 - 70 year cycle. We have also showed that the observed changes of SSN lead to a slight increase of the solar constant TSI during the cycles 23 - 24 compared to the cycle 22.

Method and device for calibrating on-orbit radiation of atmospheric absorption channels in remote sensors

Abstract: The invention relates to a method and device for calibrating on-orbit radiation of atmospheric absorption channels in remote sensors. The method comprises the following steps of: respectively obtaining moon irradiance, solar constants, instantaneous field angles and moon observation effective count value cumulative sums of a to-be-calibrated channel in a remote sensor and a reference channel and areference channel calibration coefficient; calculating a moon irradiance ratio, a solar constant ratio, an instantaneous field angle ratio and a moon observation effective count value; and inputtingthe moon irradiance ratio, the solar constant ratio, the instantaneous field angle ratio, the moon observation effective count value and the reference channel calibration coefficient into a to-be-calibrated channel calibration coefficient calculation model so as to calculate a to-be-calibrated channel calibration coefficient. According to the method and device, on-orbit radiation calibration is carried out on atmospheric absorption channels through moon observation data, so that the calibration precision is prevented from being influenced by components of the atmosphere when calibration is carried out on the atmospheric absorption channels by utilizing earth observation data.

Estimation of the Monthly Standard Diffuse and Universal Solar Eradiation for the City Varanasi, Uttar Pradesh, India

Abstract: Solar radiation data is important for supposing power capacity that can be set up from photovoltaic unit. Solar radiation tumbling on the earth’s exterior is consistent by an equipment called a total radiometer. This paper describes the process for the development of monthly standard universal and diffused radiation for the city Varanasi in Uttar Pradesh, India. It can be located at Longitude: 82.9738° E and Latitude: 25.3076° N at an elevation of 81 meters. The Gopinathan model has been used for the calculation of values of the monthly standard universal cosmic radiation. Gupta and Kreith’s models have been used for estimating the values of monthly standard diffuse cosmic radiation. The calculated data has been analyzed and the result has been simulated through MATLAB.

Solar irradiance estimation for planetary studies

Abstract: Solar irradiance is the main source of energy input to the planets of the Solar System. The solar rotation and the evolution of active regions on the surface of the Sun are two of the sources of solar irradiance variability. Nèmec et al. (2020) showed that the variability of solar irradiance is dominated by one of these two sources depending on the timescale of interest. The solar rotation dominates the variability for periods between 4-5 days and the synodic solar rotation period (27.3 days), while the evolution of active regions dominate for the remaining timescales.Usually, the irradiance measurements at Earth are extrapolated to estimate the irradiance at other planets and study the effect of solar irradiance on other planets' atmospheres (Thiemann et al., 2017). In this "lighthouse model", the irradiance source regions on the surface of the Sun are assumed to simply rotate with a Carrington sidereal period of 25.38 days. This means that the solar rotation is the only cause of variability of the irradiance in this model, and the evolution of active regions is neglected.In this work, we develop a model to calculate the irradiance at other planets by accounting for the evolution of magnetic features. Our method follows the Spectral And Total Irradiance REconstruction (SATIRE; Fligge et al. 2000; Krivova et al. 2003) approach and works by Nèmec et al. (2020) and Sowmya et al. (2021). First, the Surface Flux Transport Model (SFTM; Cameron et al. 2010) is used to obtain the time-dependent surface distribution of magnetic features (faculae and spots). Then, the solar irradiance is calculated as the sum of the contributions from the quiet Sun (i.e., regions with no magnetic activity), faculae, and spots. Our method allows calculating the solar irradiance directly at a given position within the ecliptic, regardless of the position of the Earth. We compare our irradiance calculations with those of the extrapolation method. We find that taking the evolution of active regions into account improves the estimation of solar irradiance significantly, especially when it comes to wavelengths in the visible and infrared ranges. Therefore, we suggest that our method provides more accurate estimates of solar irradiance to be used as input in studies of planetary atmospheres.We would like to note that our method of irradiance calculation is currently only statistical. We use the SFTM as we do not have information of the areas of the far-side of the Sun, which are needed in order to get the correct rotational variability. To determine real daily values of irradiance, we need to combine our calculations with methods of helioseismology, which is still a work in progress.