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GEOPHYSICAL RESEARCH LETTERS, VOL. 35, L12708, doi:10.1029/2008GL034228, 2008

Aerosol and cloud effects on solar brightening and the recent rapid warming

Christian Ruckstuhl

Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland


Rolf Philipona

Aerological Station, Federal Office of Meteorology and Climatology MeteoSwiss, Payerne, Switzerland


Klaus Behrens

Meteorologisches Observatorium Lindenberg, Deutscher Wetterdienst, Lindenberg, Germany


Martine Collaud Coen

Aerological Station, Federal Office of Meteorology and Climatology MeteoSwiss, Payerne, Switzerland


Bruno Dürr

Federal Office of Meteorology and Climatology MeteoSwiss, Zurich, Switzerland


Alain Heimo

Aerological Station, Federal Office of Meteorology and Climatology MeteoSwiss, Payerne, Switzerland


Christian Mätzler

Institute of Applied Physics, University of Bern, Bern, Switzerland


Stephan Nyeki

Physikalisch-Meteorologisches Observatorium Davos, World Radiation Center, Davos, Switzerland


Atsumu Ohmura

Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland


Laurent Vuilleumier

Aerological Station, Federal Office of Meteorology and Climatology MeteoSwiss, Payerne, Switzerland


Michael Weller

Meteorologisches Observatorium Lindenberg, Deutscher Wetterdienst, Lindenberg, Germany


Christoph Wehrli

Physikalisch-Meteorologisches Observatorium Davos, World Radiation Center, Davos, Switzerland


Antoine Zelenka

Federal Office of Meteorology and Climatology MeteoSwiss, Zurich, Switzerland


Abstract

The rapid temperature increase of 1°C over mainland Europe since 1980 is considerably larger than the temperature rise expected from anthropogenic greenhouse gas increases. Here we present aerosol optical depth measurements from six specific locations and surface irradiance measurements from a large number of radiation sites in Northern Germany and Switzerland. The measurements show a decline in aerosol concentration of up to 60%, which have led to a statistically significant increase of solar irradiance under cloud-free skies since the 1980s. The measurements confirm solar brightening and show that the direct aerosol effect had an approximately five times larger impact on climate forcing than the indirect aerosol and other cloud effects. The overall aerosol and cloud induced surface climate forcing is ∼+1 W m−2 dec−1 and has most probably strongly contributed to the recent rapid warming in Europe.

Received 9 April 2008; accepted 22 May 2008; published 24 June 2008.

Keywords: solar brightening; surface radiative.

Index Terms: 0360 Atmospheric Composition and Structure: Radiation: transmission and scattering; 1616 Global Change: Climate variability (1635, 3305, 3309, 4215, 4513); 0321 Atmospheric Composition and Structure: Cloud/radiation interaction; 1630 Global Change: Impacts of global change (1225); 3311 Atmospheric Processes: Clouds and aerosols.

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Citation: Ruckstuhl, C., et al. (2008), Aerosol and cloud effects on solar brightening and the recent rapid warming, Geophys. Res. Lett., 35, L12708, doi:10.1029/2008GL034228.