Sep 21 – 23, 2015
Royal Observatory of Belgium
Europe/Brussels timezone

The 2008 Minimum Solar Spectral Irradiance from ISS SOLAR Spectrometers Measurements

Sep 23, 2015, 9:30 AM
30m
Meridian Room (Royal Observatory of Belgium)

Meridian Room

Royal Observatory of Belgium

Avenue Circulaire - 3 - Ringlaan 1180 Brussels
3-Results from recent space missions

Speaker

Dr Gerard Thuillier (LATMOS-CNRS, 11 blvd d’Alembert, 78280 Guyancourt, France)

Description

The SOLSPEC and SolACES are spectrometers onboard the SOLAR payload of the International Space Station (ISS). The solar spectral irradiance (SSI) measurements extend from 16 to 2900 nm. In 2008, a SSI minimum occurred, which is the lowest among the measurements carried out from 1978. The SSI reconstructions and measurements play an important role in climate modeling for providing SSI at different epochs i. e. different levels of solar activity. The solar activity in 2008 is the lowest since 1978. This allows checking the capability of different solar reconstructions to estimate their accuracy by comparison with measurements. Data from the SOLSPEC and SolACES spectrometers have been merged to generate a spectrum at solar minimum activity. Comparison with spectra obtained from other instruments running at the same time as well as with published spectra will be shown. The absorption coefficient of the negative ion of hydrogen has its minimum around 1600 nm so that measurements at this wavelength provide a unique opportunity to probe the deepest layers of the solar photosphere. This is why a specific attention will be given to the IR part of the spectrum in terms of absolute value, brightness temperature of the photosphere, and contribution to the total solar irradiance. For this period, a comparison with reconstructions such as SATIRE, NRLSSI and COSI models using either theoretical or empirical approaches will be used. Difference in terms of absolute values will be discussed.

Primary author

Dr Gerard Thuillier (LATMOS-CNRS, 11 blvd d’Alembert, 78280 Guyancourt, France)

Co-authors

Dr Alexander Shapiro (Max-Planck-Institut für Sonnensystemforschung) Dr Gerhard Schmidtke (Fraunhofer Institute for Physical Measuring Technique, Heidenhofstrasse 8, 79110 Freiburg, Germany) Prof. Werner Schmutz (Physikalisch-Meteorologisches Observatorium Davos, World Radiation Center, 7260 Davos Dorf, Switzerland)

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