Enhanced Cloud Top Longwave Radiative Cooling Due To the Effect of Horizontal Radiative Transfer in the Stratocumulus to Trade Cumulus Transition Regime
Abstract
Recent studies develop the SPeedy Algorithm for Radiative TrAnsfer through CloUd Sides (SPARTACUS) to handle the influence of horizontal RT on vertical radiative fluxes within an atmospheric column. The present study applies SPARTACUS to large eddy simulation (LES)-generated cloud fields across the stratocumulus to trade cumulus transition (STCT) regime with coarse and fine vertical resolutions. The results show that, as the vertical resolution increases, radiation simulations show increasingly stronger cloud-top longwave (LW) radiative cooling. Consequently, the sharp radiative heating gradient across the cloud layer in the LES-like resolution simulations cannot be resolved with the coarse resolution simulations. Including the horizontal RT typically enhances cloud LW radiative cooling rate by less than 10% for all the cloud fields but more significantly in the cloud fields during the STCT. The enhanced cloud LW radiative cooling also occurs in the lower cloud layer in the decoupled cumulus cloud regime.
Copyright and License
© 2023. The Authors. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.
Acknowledgement
This study was supported by the Department of Energy under Grant DE-SC0022117. In addition, Ping Yang acknowledges support by the endowment funds (02-512231-10000) associated with the David Bullock Harris Chair in Geosciences at Texas A&M University. Zhaoyi Shen acknowledges the generous support of Eric and Wendy Schmidt (by recommendation of Schmidt Futures). We thank Robin Hogan and another anonymous reviewer for their insightful and helpful comments for this study. The radiation simulations in this study were performed with the computing resources provided by Texas A&M High Performance Research Computing.
Data Availability
The offline ECMWF radiation scheme (ecRad) 1.4.0 is preserved by Hogan (2020). The LW version of RRTM (RRTM_LW) is preserved by Atmospheric and Environmental Research (2010). The LES cloud field and associated forcing data are available at Ren (2023). The ERA5 monthly averaged ozone data at pressure levels are available at Hersbach et al. (2023).
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Additional details
- ISSN
- 1944-8007
- United States Department of Energy
- DE-SC0022117
- Texas A&M University
- 02-512231-10000
- Schmidt Family Foundation