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Title: Analyzing the dependence of global cloud feedback on the spatial pattern of sea surface temperature change with a Green's function approach

The spatial pattern of sea surface temperature (SST) changes has a large impact on the magnitude of cloud feedback. In this study, we seek a basic understanding of the dependence of cloud feedback on the spatial pattern of warming. Idealized experiments are carried out with an AGCM to calculate the change in global mean cloud-induced radiation anomalies (ΔR cloud) in response to imposed surface warming/cooling in 74 individual localized oceanic “patches”. Then the cloud feedback in response to a specific warming pattern can be approximated as the superposition of global cloud feedback in response to a temperature change in each region, weighted by the magnitude of the local temperature changes. When there is a warming in the tropical subsidence or extratropical regions, the local decrease of LCC results in a positive change in R cloud. Conversely, warming in tropical ascent regions increases the free-tropospheric temperature throughout the tropics, thereby enhancing the inversion strength over remote regions and inducing positive global low-cloud cover (LCC) anomalies and negative Rcloud anomalies. The Green's function approach performs reasonably well in predicting the response of global mean ΔLCC and net ΔR cloud, but poorly for shortwave and longwave components of ΔR cloud due to itsmore » ineffectiveness in predicting middle and high cloud cover changes. Finally, the approach successfully captures the change of cloud feedback in response to time-evolving CO 2-induced warming and captures the interannual variations in ΔR cloud observed by CERES. The results highlight important nonlocal influences of SST changes on cloud feedback.« less
Authors:
ORCiD logo [1] ; ORCiD logo [1] ; ORCiD logo [1]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Report Number(s):
LLNL-JRNL-733335
Journal ID: ISSN 1942-2466; 884999
Grant/Contract Number:
AC52-07NA27344
Type:
Published Article
Journal Name:
Journal of Advances in Modeling Earth Systems
Additional Journal Information:
Journal Volume: 9; Journal Issue: 5; Journal ID: ISSN 1942-2466
Publisher:
American Geophysical Union (AGU)
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; 54 ENVIRONMENTAL SCIENCES; Green's function approach; cloud feedback; spatial pattern of warming
OSTI Identifier:
1390341
Alternate Identifier(s):
OSTI ID: 1390342; OSTI ID: 1463011

Zhou, Chen, Zelinka, Mark D., and Klein, Stephen A.. Analyzing the dependence of global cloud feedback on the spatial pattern of sea surface temperature change with a Green's function approach. United States: N. p., Web. doi:10.1002/2017MS001096.
Zhou, Chen, Zelinka, Mark D., & Klein, Stephen A.. Analyzing the dependence of global cloud feedback on the spatial pattern of sea surface temperature change with a Green's function approach. United States. doi:10.1002/2017MS001096.
Zhou, Chen, Zelinka, Mark D., and Klein, Stephen A.. 2017. "Analyzing the dependence of global cloud feedback on the spatial pattern of sea surface temperature change with a Green's function approach". United States. doi:10.1002/2017MS001096.
@article{osti_1390341,
title = {Analyzing the dependence of global cloud feedback on the spatial pattern of sea surface temperature change with a Green's function approach},
author = {Zhou, Chen and Zelinka, Mark D. and Klein, Stephen A.},
abstractNote = {The spatial pattern of sea surface temperature (SST) changes has a large impact on the magnitude of cloud feedback. In this study, we seek a basic understanding of the dependence of cloud feedback on the spatial pattern of warming. Idealized experiments are carried out with an AGCM to calculate the change in global mean cloud-induced radiation anomalies (ΔRcloud) in response to imposed surface warming/cooling in 74 individual localized oceanic “patches”. Then the cloud feedback in response to a specific warming pattern can be approximated as the superposition of global cloud feedback in response to a temperature change in each region, weighted by the magnitude of the local temperature changes. When there is a warming in the tropical subsidence or extratropical regions, the local decrease of LCC results in a positive change in Rcloud. Conversely, warming in tropical ascent regions increases the free-tropospheric temperature throughout the tropics, thereby enhancing the inversion strength over remote regions and inducing positive global low-cloud cover (LCC) anomalies and negative Rcloud anomalies. The Green's function approach performs reasonably well in predicting the response of global mean ΔLCC and net ΔRcloud, but poorly for shortwave and longwave components of ΔRcloud due to its ineffectiveness in predicting middle and high cloud cover changes. Finally, the approach successfully captures the change of cloud feedback in response to time-evolving CO2-induced warming and captures the interannual variations in ΔRcloud observed by CERES. The results highlight important nonlocal influences of SST changes on cloud feedback.},
doi = {10.1002/2017MS001096},
journal = {Journal of Advances in Modeling Earth Systems},
number = 5,
volume = 9,
place = {United States},
year = {2017},
month = {8}
}