Time-Dependent Cryospheric Longwave Surface Emissivity Feedback in the Community Earth System Model
Frozen and unfrozen surfaces exhibit different longwave surface emissivities with different spectral characteristics, and outgoing longwave radiation and cooling rates are reduced for unfrozen scenes relative to frozen ones. Here physically realistic modeling of spectrally resolved surface emissivit...
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ftcdlib:oai:escholarship.org/ark:/13030/qt8ps974q7 2023-05-15T13:11:43+02:00 Time-Dependent Cryospheric Longwave Surface Emissivity Feedback in the Community Earth System Model Kuo, C Feldman, DR Huang, X Flanner, M Yang, P Chen, X 789 - 813 2018-01-27 application/pdf https://escholarship.org/uc/item/8ps974q7 unknown eScholarship, University of California qt8ps974q7 https://escholarship.org/uc/item/8ps974q7 public Journal of Geophysical Research: Atmospheres, vol 123, iss 2 climate feedback longwave emissivity temporal radiative kernel Atmospheric Sciences Physical Geography and Environmental Geoscience article 2018 ftcdlib 2021-04-16T07:11:49Z Frozen and unfrozen surfaces exhibit different longwave surface emissivities with different spectral characteristics, and outgoing longwave radiation and cooling rates are reduced for unfrozen scenes relative to frozen ones. Here physically realistic modeling of spectrally resolved surface emissivity throughout the coupled model components of the Community Earth System Model (CESM) is advanced, and implications for model high-latitude biases and feedbacks are evaluated. It is shown that despite a surface emissivity feedback amplitude that is, at most, a few percent of the surface albedo feedback amplitude, the inclusion of realistic, harmonized longwave, spectrally resolved emissivity information in CESM1.2.2 reduces wintertime Arctic surface temperature biases from −7.2 ± 0.9 K to −1.1 ± 1.2 K, relative to observations. The bias reduction is most pronounced in the Arctic Ocean, a region for which Coupled Model Intercomparison Project version 5 (CMIP5) models exhibit the largest mean wintertime cold bias, suggesting that persistent polar temperature biases can be lessened by including this physically based process across model components. The ice emissivity feedback of CESM1.2.2 is evaluated under a warming scenario with a kernel-based approach, and it is found that emissivity radiative kernels exhibit water vapor and cloud cover dependence, thereby varying spatially and decreasing in magnitude over the course of the scenario from secular changes in atmospheric thermodynamics and cloud patterns. Accounting for the temporally varying radiative responses can yield diagnosed feedbacks that differ in sign from those obtained from conventional climatological feedback analysis methods. Article in Journal/Newspaper albedo Arctic Arctic Ocean University of California: eScholarship Arctic Arctic Ocean |
institution |
Open Polar |
collection |
University of California: eScholarship |
op_collection_id |
ftcdlib |
language |
unknown |
topic |
climate feedback longwave emissivity temporal radiative kernel Atmospheric Sciences Physical Geography and Environmental Geoscience |
spellingShingle |
climate feedback longwave emissivity temporal radiative kernel Atmospheric Sciences Physical Geography and Environmental Geoscience Kuo, C Feldman, DR Huang, X Flanner, M Yang, P Chen, X Time-Dependent Cryospheric Longwave Surface Emissivity Feedback in the Community Earth System Model |
topic_facet |
climate feedback longwave emissivity temporal radiative kernel Atmospheric Sciences Physical Geography and Environmental Geoscience |
description |
Frozen and unfrozen surfaces exhibit different longwave surface emissivities with different spectral characteristics, and outgoing longwave radiation and cooling rates are reduced for unfrozen scenes relative to frozen ones. Here physically realistic modeling of spectrally resolved surface emissivity throughout the coupled model components of the Community Earth System Model (CESM) is advanced, and implications for model high-latitude biases and feedbacks are evaluated. It is shown that despite a surface emissivity feedback amplitude that is, at most, a few percent of the surface albedo feedback amplitude, the inclusion of realistic, harmonized longwave, spectrally resolved emissivity information in CESM1.2.2 reduces wintertime Arctic surface temperature biases from −7.2 ± 0.9 K to −1.1 ± 1.2 K, relative to observations. The bias reduction is most pronounced in the Arctic Ocean, a region for which Coupled Model Intercomparison Project version 5 (CMIP5) models exhibit the largest mean wintertime cold bias, suggesting that persistent polar temperature biases can be lessened by including this physically based process across model components. The ice emissivity feedback of CESM1.2.2 is evaluated under a warming scenario with a kernel-based approach, and it is found that emissivity radiative kernels exhibit water vapor and cloud cover dependence, thereby varying spatially and decreasing in magnitude over the course of the scenario from secular changes in atmospheric thermodynamics and cloud patterns. Accounting for the temporally varying radiative responses can yield diagnosed feedbacks that differ in sign from those obtained from conventional climatological feedback analysis methods. |
format |
Article in Journal/Newspaper |
author |
Kuo, C Feldman, DR Huang, X Flanner, M Yang, P Chen, X |
author_facet |
Kuo, C Feldman, DR Huang, X Flanner, M Yang, P Chen, X |
author_sort |
Kuo, C |
title |
Time-Dependent Cryospheric Longwave Surface Emissivity Feedback in the Community Earth System Model |
title_short |
Time-Dependent Cryospheric Longwave Surface Emissivity Feedback in the Community Earth System Model |
title_full |
Time-Dependent Cryospheric Longwave Surface Emissivity Feedback in the Community Earth System Model |
title_fullStr |
Time-Dependent Cryospheric Longwave Surface Emissivity Feedback in the Community Earth System Model |
title_full_unstemmed |
Time-Dependent Cryospheric Longwave Surface Emissivity Feedback in the Community Earth System Model |
title_sort |
time-dependent cryospheric longwave surface emissivity feedback in the community earth system model |
publisher |
eScholarship, University of California |
publishDate |
2018 |
url |
https://escholarship.org/uc/item/8ps974q7 |
op_coverage |
789 - 813 |
geographic |
Arctic Arctic Ocean |
geographic_facet |
Arctic Arctic Ocean |
genre |
albedo Arctic Arctic Ocean |
genre_facet |
albedo Arctic Arctic Ocean |
op_source |
Journal of Geophysical Research: Atmospheres, vol 123, iss 2 |
op_relation |
qt8ps974q7 https://escholarship.org/uc/item/8ps974q7 |
op_rights |
public |
_version_ |
1766248688251830272 |