Investigation of solar UV irradiance variation on hourly to decadal time scales and its impact on middle atmospheric ozone and ozone-climate interaction

• Antragsteller: Dr. Mark Weber
• Fachliche Zuordnung: Physik und Chemie der Atmosphäre
• Förderung: Förderung von 2005 bis 2011
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 5454950

Using SCIAMACHY data, for the first time solar cycle variations of spectral solar irradiances were derived for the visible and NIR spectral region. The estimated contribution of the visible spectral region to solar cycle changes in the total solar irradiance (solar constant) during the 11-year solar cycle is estimated to be about 45%. Comparison of SCIAMACHY results with SUSIM satellite and SATIRE empirical model data, however, show that SCIAMACHY tends to underestimate the solar cycle contribution. The observed solar cycle spectral variations were extrapolated from short-term 27-day variations of SCIAMACHY data using solar proxies for faculae brightening and sunspot darkening. From short-term variation it is challenging to derive natural decadal variations beyond that are contained in the solar proxies. One main goal of this study is to further improve upon the SCIAMACHY calibration in order to investigate in a more direct way longer term solar variations using more than six years of SCIAMACHY data. The validity of our solar proxy model to estimate solar variability will be extended to other satellite data, SUSIM (< 400 nm) and SIM (> 300 nm) as well as to the SATIRE empirical model data to validate and compare our SCIAMACHY results. For a better understanding on the radiative impact of solar irradiance variations on upper atmosphere ozone, the solar cycle irradiance changes derived from this study and implemented into the Bremen chemicaltransport models are used to compare modeled ozone variations with 11-year and 27-day solar cycles with SCIAMACHY and SABER satellite observations.

• DFG-Verfahren: Schwerpunktprogramme
• Teilprojekt zu: SPP 1176: Klima und Wetter des Systems Sonne/Erde
• Beteiligte Personen: Dr. Heinrich Bovensmann; Professor Dr. John Philip Burrows; Professor Christian von Savigny, Ph.D.