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Title: 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. In this paper 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 andmore » decreasing in magnitude over the course of the scenario from secular changes in atmospheric thermodynamics and cloud patterns. Finally, accounting for the temporally varying radiative responses can yield diagnosed feedbacks that differ in sign from those obtained from conventional climatological feedback analysis methods.« less
Authors:
ORCiD logo [1] ; ORCiD logo [1] ; ORCiD logo [2] ; ORCiD logo [2] ;  [3] ;  [2]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Climate and Ecosystem Sciences Division
  2. Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Climate and Space Sciences and Engineering
  3. Texas A & M Univ., College Station, TX (United States). Dept. of Atmospheric Sciences
Publication Date:
Grant/Contract Number:
AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Journal of Geophysical Research: Atmospheres
Additional Journal Information:
Journal Volume: 123; Journal Issue: 2; Journal ID: ISSN 2169-897X
Publisher:
American Geophysical Union
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; climate feedback; longwave; emissivity; temporal; radiative kernel
OSTI Identifier:
1464160
Alternate Identifier(s):
OSTI ID: 1417495

Kuo, Chaincy, Feldman, Daniel R., Huang, Xianglei, Flanner, Mark, Yang, Ping, and Chen, Xiuhong. Time-Dependent Cryospheric Longwave Surface Emissivity Feedback in the Community Earth System Model. United States: N. p., Web. doi:10.1002/2017JD027595.
Kuo, Chaincy, Feldman, Daniel R., Huang, Xianglei, Flanner, Mark, Yang, Ping, & Chen, Xiuhong. Time-Dependent Cryospheric Longwave Surface Emissivity Feedback in the Community Earth System Model. United States. doi:10.1002/2017JD027595.
Kuo, Chaincy, Feldman, Daniel R., Huang, Xianglei, Flanner, Mark, Yang, Ping, and Chen, Xiuhong. 2018. "Time-Dependent Cryospheric Longwave Surface Emissivity Feedback in the Community Earth System Model". United States. doi:10.1002/2017JD027595.
@article{osti_1464160,
title = {Time-Dependent Cryospheric Longwave Surface Emissivity Feedback in the Community Earth System Model},
author = {Kuo, Chaincy and Feldman, Daniel R. and Huang, Xianglei and Flanner, Mark and Yang, Ping and Chen, Xiuhong},
abstractNote = {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. In this paper 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. Finally, accounting for the temporally varying radiative responses can yield diagnosed feedbacks that differ in sign from those obtained from conventional climatological feedback analysis methods.},
doi = {10.1002/2017JD027595},
journal = {Journal of Geophysical Research: Atmospheres},
number = 2,
volume = 123,
place = {United States},
year = {2018},
month = {1}
}