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

• Erstellungsjahr: 2013

Zusammenfassung der Projektergebnisse

The main objective in the project was the use of satellite observations of vertical ozone profiles and spectral solar irradiances (SSI) to gain further insights on the solar radiation influence on the earth's upper atmospheres with emphasis on the solar 27d rotation period and the 11 year solar cycle. SCIAMACHY was the first satellite instrument providing daily spectral solar irradiances (SSI) from the UV, visible and near infrared. The comparisons with other solar data from space and ground showed good agreement too within a few percent up to 1700 nm. Expressing SCIAMACHY irradiance variations over several solar rotations in terms of solar proxies for sunspot darkening and faculae brightening permits the extrapolation of SCIAMACHY SSI variations to the 11-year solar cycle scales which is very relevant for studying solar radiation impact on the earth’s climate using climate models. It was shown that about half of the 0.1% change in the solar constant over solar cycle 23 has originated from the visible and IR spectral region. A particular challenge is the solar cycle variation estimate for the near UV (300-400 nm), where recent SIM observations indicate changes during solar cycle 23 that are much higher than expected from indirect SCIAMACHY observations and other empirical models (assuming solar surface magnetic activity as primary driver for SSI variations) as well as observations from other satellite data in earlier solar cycles. SCIAMACHY limb ozone vertical profiles from 2003 to 2008 were analyzed for signatures of the 27-day solar rotation. It was found that this signature is highly variable in time and that even under solar maximum condition this signal can vanish for several months. On average the sensitivity above 30 km is a 0.2% ozone change in the 205 nm solar flux (important for ozone production) near solar maximum, which is smaller than found in earlier studies and prior solar cycles. Daytime variations in tropical mesospheric ozone yield changes of up to 60% from the daytime mean based upon SABER ozone data and peak anomalies are generally higher during equinox. SABER results were compared for the first time with an output of a chemistry climate model, here the HAMMONIA model. SABER ozone from the 9.6 micrometer retrieval agrees qualitatively very well with HAMMONIA, however, little agreement was found between modeled and SABER temperatures above 0.01 hPa. The low temperature variations of a few degrees during daytime may suggest that photochemical processes are the main driver for daytime ozone variations and to a lesser degree transport related to tides.

Projektbezogene Publikationen (Auswahl)

• Solar variability from 240 to 1750 nm in terms of faculae brightening and sunspot darkening from SCIAMACHY. Astrophys. J., 700:1884– 1895, 2009
  J. Pagaran, M. Weber, and J. P. Burrows
  
• Daytime ozone and temperature variations in the mesosphere: a comparison between SABER observations and HAMMONIA model. Atmos. Chem. Phys., 10:8331–8339, 2010
  S. Dikty, H. Schmidt, M. Weber, C. von Savigny, and M. G. Mlynczak
  
• Modulations of the 27-day solar cycle signal in stratospheric ozone from SCIAMACHY. J. Geophys. Res., 115, 2010
  S. Dikty, M. Weber, C. von Savigny, T. Sonkaew, A. Rozanov, and J. P. Burrows
  
• Intercomparison of SCIAMA- CHY and SIM vis-ir irradiance over several solar rotational timescales. Astron. Astrophys., 528:A67, 2011
  J. Pagaran, J. Harder, M. Weber, L. Floyd, and J. P. Burrows
  
• Solar spectral irradiance variations in 240-1600 nm during the recent solar cycles 21-23. Sol. Phys., 272:159–188, 2011
  J. Pagaran., M. Weber, M. DeLand, L. Floyd, and J. P. Burrows
  
• Sensitivity of equatorial mesopause temperatures to the 27-day solar cycle. Geophys. Res. Lett., 39, 2012
  C. von Savigny, K.-U. Eichmann, C. E. Robert, J. P. Burrows, and M. Weber
  
• The influence of spectral solar irradiance data on stratospheric heating rates during the 11 year solar cycle. Geophys. Res. Lett., 2012
  S. Oberländer, U. Langematz, K. Matthes, M. Kunze, A. Kubin, J. W. Harder, N. A. Krivova, S. K. Solanki, J. Pagaran, and M. Weber
  
• Investigation of solar irradiance variations and their impact on middle atmospheric ozone. In F.-J. Lübken, editor, Climate And Weather of the Sun-Earth System (CAWSES): Highlights from a priority program, chapter 3, pages 39–54. Springer Atmospheric Sciences, Dordrecht, The Netherlands, 2013
  M. Weber, J. Pagaran, S. Dikty, C. von Savigny, J. P. Burrows, M. DeLand, L. E. Floyd, J. W. Harder, M. G. Mlynczak, and H. Schmidt
  
• Recent variability of the solar spectral irradiance and its impact on climate modelling. Atmos. Chem. Phys., 13:3945–3977, 2013
  I. Ermolli, K. Matthes, T. Dudok de Wit, N. A. Krivova, K. Tourpali, M. Weber, Y. C. Unruh, L. Gray, U. Langematz, P. Pilewskie, E. Rozanov, W. Schmutz, A. Shapiro, S. K. Solanki, and T. N. Woods
  
• The role of the solar irradiance variability in the evolution of the middle atmosphere during 2004-2009. J. Geophys. Res., 118:3781–3793, 2013
  A. Shapiro, E. Rozanov, A. Shapiro, T. Egorova, J. W. Harder, M. Weber, A. K. Smith, W. Schmutz, and T. Peter