scholarly journals Geographic Dependence of the Solar Irradiance Spectrum at Intermediate to High Frequencies

2019 ◽  
Vol 12 (2) ◽  
Author(s):  
Golan Bel ◽  
M. M. Bandi
Keyword(s):  
Solar Irradiance ◽  
High Frequencies ◽  
Irradiance Spectrum

In-flight calibration of the SCIAMACHY solar irradiance spectrum

2003 ◽  
Vol 32 (11) ◽  
pp. 2129-2134 ◽  
Author(s):  
J. Skupin ◽  
S. Noel ◽  
M.W. Wuttke ◽  
H. Bovensmann ◽  
J.P. Burrows ◽  
...  
Keyword(s):  
Solar Irradiance ◽  
Irradiance Spectrum

The Solar Irradiance Spectrum at Solar Activity Minimum Between Solar Cycles 23 and 24

Solar Physics ◽  
2013 ◽  
Vol 289 (6) ◽  
pp. 1931-1958 ◽  
Author(s):  
G. Thuillier ◽  
D. Bolsée ◽  
G. Schmidtke ◽  
T. Foujols ◽  
B. Nikutowski ◽  
...  
Keyword(s):  
Solar Activity ◽  
Solar Irradiance ◽  
Solar Cycles ◽  
Solar Activity Minimum ◽  
Irradiance Spectrum

scholarly journals Reference solar irradiance spectra and consequences of their disparities in remote sensing of the ocean colour

2007 ◽  
Vol 25 (6) ◽  
pp. 1235-1252 ◽  
Author(s):  
P. Shanmugam ◽  
Y. H. Ahn
Keyword(s):  
Remote Sensing ◽  
Solar Irradiance ◽  
Near Infrared ◽  
Atmospheric Correction ◽  
Solar Spectrum ◽  
Wavelength Region ◽  
Radiometric Calibration ◽  
Ocean Colour ◽  
Short Wavelength Region ◽  
Irradiance Spectrum

Abstract. Satellite ocean colour missions require a standard extraterrestrial solar irradiance spectrum in the visible and near-infrared (NIR) for use in the process of radiometric calibration, atmospheric correction and normalization of water-leaving radiances from in-situ measurements. There are numerous solar irradiance spectra (or models) currently in use within the ocean colour community and related domains. However, these irradiance spectra, constructed from single and/or multiple measurements sets or models, have noticeable differences – ranging from about ±1% in the NIR to ±6% in the short wavelength region (ultraviolet and blue) – caused primarily by the variation in the solar activity and uncertainties in experimental data from different instruments. Such differences between the applied solar irradiance spectra may have quite important consequences in reconciliation, comparison and validation of the products resulting from different ocean colour instruments. Thus, it is prudent to examine the model-to-model differences and ascertain an appropriate solar irradiance spectrum for use in future ocean colour research and validation purposes. This study first describes the processes which generally require the application of a solar irradiance spectrum, and then investigates the eight solar irradiance spectra (widely in use within the remote sensing community) selected on the basis of the following criteria: minimum spectral range of 350–1200 nm with adequate spectral resolution, completely or mostly based on direct measurements, minimal error range, intercomparison with other experiments and update of data. The differences in these spectra in absolute terms and in the SeaWiFS and MERIS in-band irradiances and their consequences on the retrieval algorithms of chlorophyll and suspended sediment are analyzed. Based on these detailed analyses, this study puts forward the solar irradiance spectrum most appropriate for all aspects of research, calibration and validation in ocean colour remote sensing. For an improved approximation of the extraterrestrial solar spectrum in the ultraviolet-NIR domain this study also proposes a new solar constant value determined from space-borne measurements of the last three decades.

scholarly journals The UV-A and visible solar irradiance spectrum: inter-comparison of absolutely calibrated, spectrally medium resolution solar irradiance spectra from balloon- and satellite-borne measurements

2005 ◽  
Vol 5 (7) ◽  
pp. 1879-1890 ◽  
Author(s):  
W. Gurlit ◽  
H. Bösch ◽  
H. Bovensmann ◽  
J. P. Burrows ◽  
A. Butz ◽  
...  
Keyword(s):  
Spectral Range ◽  
Solar Irradiance ◽  
Rayleigh Scattering ◽  
Solar Spectrum ◽  
Visible Spectral Range ◽  
Wavelength Interval ◽  
Maximum Resolution ◽  
Medium Resolution ◽  
Moderate Resolution ◽  
Irradiance Spectrum

Abstract. Within the framework of the ENVISAT/-SCIAMACHY satellite validation, solar irradiance spectra are absolutely measured at moderate resolution in the UV/visible spectral range (in the UV from 316.7-418 nm and the visible from 400-652 nm at a full width half maximum resolution of 0.55 nm and 1.48 nm, respectively) from aboard the azimuth-controlled LPMA/DOAS balloon gondola at around 32 km balloon float altitude. After accounting for the atmospheric extinction due to Rayleigh scattering and gaseous absorption (O3 and NO2), the measured solar spectra are compared with previous observations. Our solar irradiance spectrum perfectly agrees within +0.03% with the re-calibrated Kurucz et al. (1984) solar spectrum (Fontenla et al., 1999, called MODTRAN 3.7) in the visible spectral range (415-650 nm), but it is +2.1% larger in the (370-415 nm) wavelength interval, and -4% smaller in the UV-A spectral range (316.7-370 nm), when the Kurucz spectrum is convolved to the spectral resolution of our instrument. Similar comparisons of the SOLSPEC (Thuillier et al., 1997, 1998a, b) and SORCE/SIM (Harder et al., 2000) solar spectra with MODTRAN 3.7 confirms our findings with the values being -0.5%, +2%, and -1.4% for SOLSPEC -0.33%, -0.47%, and -6.2% for SORCE/SIM, respectively. Comparison of the SCIAMACHY solar spectrum from channels 1 to 4 (- re-calibrated by the University of Bremen -) with MODTRAN 3.7 indicates an agreement within -0.4% in the visible spectral range (415-585 nm), -1.6% within the 370-415 nm, and -5.7% within 325-370 nm wavelength interval, in agreement with the results of the other sensors. In agreement with findings of Skupin et al. (2002) our study emphasizes that the present ESA SCIAMACHY level 1 calibration is systematically +15% larger in the considered wavelength intervals when compared to all available other solar irradiance measurements.

Solar irradiance spectrum at Madrid

1982 ◽  
Vol 16 (9) ◽  
pp. 2237-2240 ◽  
Author(s):  
A. Pons ◽  
A. Corróns
Keyword(s):  
Solar Irradiance ◽  
Irradiance Spectrum

Quasi-Periodic Oscillations in Dwarf Novae

1979 ◽  
Vol 46 ◽  
pp. 77-88
Author(s):  
Edward L. Robinson
Keyword(s):  
Binary Systems ◽  
Outer Edge ◽  
Light Curves ◽  
Close Binary ◽  
Bright Spot ◽  
Dwarf Novae ◽  
Periodic Oscillations ◽  
High Frequencies ◽  
Short Period ◽  
Typical Time

Three distinct kinds of rapid variations have been detected in the light curves of dwarf novae: rapid flickering, short period coherent oscillations, and quasi-periodic oscillations. The rapid flickering is seen in the light curves of most, if not all, dwarf novae, and is especially apparent during minimum light between eruptions. The flickering has a typical time scale of a few minutes or less and a typical amplitude of about .1 mag. The flickering is completely random and unpredictable; the power spectrum of flickering shows only a slow decrease from low to high frequencies. The observations of U Gem by Warner and Nather (1971) showed conclusively that most of the flickering is produced by variations in the luminosity of the bright spot near the outer edge of the accretion disk around the white dwarf in these close binary systems.

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