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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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Journal ArticleDOI
01 Jan 2008
TL;DR: In this paper, the authors revisited Pouillet's work with current knowledge and found that Poulet's results are quite robust. But they also evaluated the total absorption of solar radiation by the atmosphere.
Abstract: Claude Pouillet greatly contributed to the development of climate sciences by estimating the solar constant, i.e. the incoming solar radiation at the top of the atmosphere (also called total solar irradiance). The value obtained by Pouillet is only 10% lower than modern estimates, but Pouillet's contribution is sometimes omitted or underestimated. He also evaluated the total absorption of solar radiation by the atmosphere. The aim of this paper is to revisit Pouillet's work with our current knowledge. It appears that Pouillet's results are quite robust.

8 citations

DOI
01 Nov 1982
TL;DR: In this article, the authors presented the results of a study made to compute the total precipitable water in the atmosphere over India using radiosonde and other data, as part of a program for the computation of direct, global and diffuse solar radiation at the ground from the solar constant.
Abstract: Electromagnetic radiation, in its passage through the atmosphere, is attenuated by absorption and scattering by atmospheric gases, dust and aerosols. The most important absorber is water vapour and the most significant parameter in atmospheric absorption studies is the total precipitable water in the atmosphere. The present paper summarises the results of a study made to compute the total precipitable water in the atmosphere over India using radiosonde and other data, as part of a programme for the computation of direct, global and diffuse solar radiation at the ground from the solar constant. Using values of air temperature and dew point from the ground up to 250 mb at 19 radiosonde stations and surface water vapour mixing ratio values at 105 surface observatories in India, precipitable water amounts have been computed for 124 stations, for each month and for the whole year. The paper describes the techniques used to extend the total precipitable water amounts derived from radiosonde data at 19 stations to 124 stations covering the major climatic zones in the country and presents the results in the form of 12 maps showing the spatial and temporal distribution of total precipitable water over India

8 citations

01 Jan 2011
TL;DR: In this article, the authors presented the most recent progress in understanding SSI variability not only in the UV but also in the vis-IR spectral region using SCIAMACHY data.
Abstract: The sun's radiative output is the primary energy input to the Earth, planets, and the entire heliosphere. It determines the thermal structure of the Earth s atmosphere, and overall it sustains life as we know it. The solar spectral irradiance (SSI) determines the general circulation, ozone photochemistry, and weather-climate system. Both SSI and the total solar irradiance (TSI or 'solar constant') vary in time. The 'solar constant' is obtained by integrating SSI over the entire electromagnetic spectrum. It is now established to vary about 0.2 0.4% during the 27-day solar rotation due to transit of active region across the solar disk and 0.1% over an 11-year solar cycle due to variations of magnetic surface activity of the sun related to the reversal of the solar magnetic field. While SSI variability in the UV is moderately well understood, little is known about variability in the optical and near IR (vis-IR) spectral range. This is because while the variations in UV are large, vis-IR variations are small, which are within the noise level of the instrument. The overall goal of this dissertation, therefore, is to improve our understanding of SSI variability especially at longer wavelengths beyond the UV. Regular monitoring of SSI from space covering the entire UV and vis-IR has become available at a moderately high spectral resolution with SCIAMACHY aboard ENVISAT since 2002. This cumulative dissertation presents in three published manuscripts the most recent progress in understanding SSI variability not only in the UV but also in the vis-IR spectral region using SCIAMACHY data. The first published manuscript ad- dresses the validation of radiometrically calibrated SSI from SCIAMACHY to existing SSI data (from ground and space) and to compare SCIAMACHY SSI variations with various other satellite data from SIM onboard SORCE, SUSIM onboard UARS, and SBUVs. The second published manuscript describes the parametrization of SCIAMACHY SSI time series in terms of solar proxies: Mg II core-to-wing (ctw) ratio for faculae brightening and photometric sunspot index (PSI) for sunspot darkening. This simple irradiance model is referred to as the SCIA proxy model. This model allows us to estimate past solar irradiance variations over several decades well beyond the observation period of the SCIAMACHY satellite. Most satellites observing in the optical spectral range suffer from hard radiation in space, particular in the UV, therefore these satellites optically degrade with time. The parametrization using the solar proxy model also enables the application of a simple degradation correction with the need for detailed re-calibration of solar irradiance measurements, which is not always possible or feasible. So far these two goals focus on short timescales (days to several months). The third published manuscript deals with the application of the model to reconstruct daily SSI variability from 1978 to present, covering several decades. The reconstructed SSI from SCIA proxy on daily to decadal timescales are compared to the solar…

7 citations

Journal ArticleDOI
TL;DR: In this article, the authors report an photospheric limb-darkening measurements obtained at the McMath Solar Telescope in 1980 July, September, and October as part of a continuing program to study possible long-term variations in the photosphere emergent flux.
Abstract: We report an photospheric limb-darkening measurements obtained at the McMath Solar Telescope in 1980 July, September, and October as part of a continuing program to study possible long-term variations in the photospheric emergent flux. A total of 243 usable full-diameter scans was recorded over 7 days in the clean continuum window at 4451.25 A. Individual scans were fitted to a fifth order polynomial in xi = ln..mu.., and a mean limb-darkening curve was derived for each day. The standard deviation of the daily mean of intensities ranged between 0.08% and 0.12% for all ..mu..>0.15. We note that the limb darkening decreased significantly between September 25 and 26. This change of the limb-darkening curve is not readily understandable in terms of variations in scattered light, seeing, or nonlinear photometric gain. We suggest that it is caused by a decrease of the temperature gradient in the upper photosphere, in the region above approximately tau/sub 5000/ = 0.5. The small increase in effective temperature that might accompany this limb-darkening variation is estimated using a standard radiative equilibrium photospheric model. We note that the increase of effective temperature corresponds in sign with an increase in the solar irradiance reported between September 25 and 26more » from both the Nimbus 7 ERB and the SMM ACRIM radiometers.« less

7 citations

Journal ArticleDOI
TL;DR: A review of the science of sun photometry, tracing its origins back to research by Newton, can be found in this article, where the authors present a global network of solar photometers providing information about the spectral variation of aerosol optical depth and information mapping atmospheric trace constituents.
Abstract: This paper reviews the science of sun photometry, tracing its origins back to research by Newton. Modern sun photometry originated through the works of the Angstrom family in Sweden and the Smithsonian Astrophysical Observatory's program started by Langley and energized over many years by Abbott. In the case of the Smithsonian's program, the objective was to search for evidence between fluctuations in climate and solar radiation. Multiwavelength sun photometry as a science came about primarily by turning this nuisance factor of atmospheric corrections into useful scientific information. Modern sun photometry uses solar radiometers calibrated to accuracies of one part in a thousand and routinely assess atmospheric spectral optical depths to high accuracy. There is presently a global network of sun photometers providing information about the spectral variation of aerosol optical depth and information mapping atmospheric trace constituents.

7 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20238
202215
20219
20202
201911
201810