The Solar Spectral Irradiance From 200 to 2400 nm as Measured During the ATLAS and EURECA Missions


Authors:          G. Thuillier (1), M. Hersé (1), D. Labs (2), P. C. Simon (3)

Affilitations:    1) Service d'Aéronomie du CNRS, Verrières-le-Buisson, France

                        2) Landessternwarte, Heidelberg, Germany

                        3) Institut d'Aéronomie Spatiale de Belgique, Brussels, Belgique


            The planetary atmospheres properties as composition, thermal structure and dynamics need the knowledge of the solar spectrum as energy input wavelength dependent.  Modeling of the atmosphere is improving in term of accuracy which requires in parallel an improuvement of the solar input accuracy.

            The SOLSPEC investigation is dedicated to the measurement of the solar spectrum from 200 to 2400 nm.  The SOLSPEC instrument is made of three spectrometers observing in UV, visible and IR domains.  It carries calibration lamps to monitor in space the spectrometers wavelength and photometric scales.  It is calibrated in the absolute scale using a blackbody.  It flew with the three ATLAS (March 1992, April 1993, November 1994) Shuttle missions and on the EURECA platform (September 1992 to January 1993).

            We present the data gathered during these missions.  The mean accuracy of these measurements is 3%.  In UV and visible, comparisons with data from the other ATLAS and UARS instruments will be shown and discussed.

            By assembling the best measurements, we have built a spectrum extending from 200 to 2400 nm.  This spectrum complemented above 2400 nm allows to calculate the total solar irradiance which is compared with its measurement made at the same time.  We will discuss the difference between these two results.  Comparisons with several recent spectra up to the IR domain will be shown.

            Future plan for SOLSPEC will be presented.