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Radiative Heating of High-Level Clouds and its Impacts on Climate
  • Kerstin Haslehner,
  • Blaz Gasparini,
  • Aiko Voigt
Kerstin Haslehner
Department of Meteorology and Geophysics, University of Vienna

Corresponding Author:[email protected]

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Blaz Gasparini
University of Vienna
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Aiko Voigt
Department of Meteorology and Geophysics, University of Vienna
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Abstract

The interactions of clouds with radiation influence climate. Many of these impacts appear to be related to the radiative heating and cooling from high-level clouds in the upper troposphere, but few studies have explicitly tested this. Here, we use simulations with the ICON-ESM global atmosphere model to understand how high-level clouds through their radiative heating and cooling of the atmosphere, influence the large-scale atmospheric circulation and precipitation in the present-day climate. We introduce a new method to diagnose the radiative heating of high-level clouds: we use a temperature threshold of -35°C to define high-level clouds and also include the lower parts of these clouds at warmer temperatures. The inclusion of the lower cloud parts circumvents the creation of artificial cloud boundaries and strong artificial radiative heating at the temperature threshold. To isolate the impact of high-level clouds, we analyze simulations with active cloud-radiative heating, with the radiative heating from high-level clouds set to zero, and with the radiative heating from all clouds set to zero. We show that the radiative interactions of high-level clouds warm the troposphere and strengthen the eddy-driven jet streams, but have no impact on the strength of the Hadley circulation and the latitude of the Intertropical Convergence Zone. Consistent with their positive radiative heating and energetic arguments, high-level clouds reduce precipitation throughout the tropics and lower midlatitudes. Overall, our results confirm that the radiative interactions of high-level clouds have important impacts on climate and highlight the need for better representing their radiative interactions in models.
24 Jan 2024Submitted to ESS Open Archive
24 Jan 2024Published in ESS Open Archive