Improved representation of surface spectral emissivity in a global climate model and its impact on simulated climate
Surface longwave emissivity can be less than unity and vary significantly with frequency. However, most climate models still assume a blackbody surface in the longwave (LW) radiation scheme of their atmosphere models. This study incorporates realistic surface spectral emissivity into the atmospheric...
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ftcdlib:oai:escholarship.org/ark:/13030/qt67m6d09d 2023-05-15T18:17:17+02:00 Improved representation of surface spectral emissivity in a global climate model and its impact on simulated climate Huang, X Chen, X Flanner, M Yang, P Feldman, D Kuo, C 3711 - 3727 2018-05-01 application/pdf https://escholarship.org/uc/item/67m6d09d unknown eScholarship, University of California qt67m6d09d https://escholarship.org/uc/item/67m6d09d public Journal of Climate, vol 31, iss 9 Meteorology & Atmospheric Sciences Atmospheric Sciences Oceanography Geomatic Engineering article 2018 ftcdlib 2021-06-20T14:23:16Z Surface longwave emissivity can be less than unity and vary significantly with frequency. However, most climate models still assume a blackbody surface in the longwave (LW) radiation scheme of their atmosphere models. This study incorporates realistic surface spectral emissivity into the atmospheric component of the Community Earth System Model (CESM), version 1.1.1, and evaluates its impact on simulated climate. By ensuring consistency of the broadband surface longwave flux across different components of the CESM, the top-of-the-atmosphere (TOA) energy balance in the modified model can be attained without retuning the model. Inclusion of surface spectral emissivity, however, leads to a decrease of net upward longwave flux at the surface and a comparable increase of latent heat flux. Global-mean surface temperature difference between the modified and standard CESM simulation is 0.20 K for the fully coupled run and 0.45 K for the slab-ocean run. Noticeable surface temperature differences between the modified and standard CESM simulations are seen over the Sahara Desert and polar regions. Accordingly, the climatological mean sea ice fraction in the modified CESM simulation can be less than that in the standard CESM simulation by as much as 0.1 in some regions. When spectral emissivities of sea ice and open ocean surfaces are considered, the broadband LW sea ice emissivity feedback is estimated to be -0.003 W m-2 K-1, assuming flat ice emissivity as sea ice emissivity, and 0.002 W m-2 K-1, assuming coarse snow emissivity as sea ice emissivity, which are two orders of magnitude smaller than the surface albedo feedback. Article in Journal/Newspaper Sea ice University of California: eScholarship |
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Open Polar |
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University of California: eScholarship |
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ftcdlib |
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topic |
Meteorology & Atmospheric Sciences Atmospheric Sciences Oceanography Geomatic Engineering |
spellingShingle |
Meteorology & Atmospheric Sciences Atmospheric Sciences Oceanography Geomatic Engineering Huang, X Chen, X Flanner, M Yang, P Feldman, D Kuo, C Improved representation of surface spectral emissivity in a global climate model and its impact on simulated climate |
topic_facet |
Meteorology & Atmospheric Sciences Atmospheric Sciences Oceanography Geomatic Engineering |
description |
Surface longwave emissivity can be less than unity and vary significantly with frequency. However, most climate models still assume a blackbody surface in the longwave (LW) radiation scheme of their atmosphere models. This study incorporates realistic surface spectral emissivity into the atmospheric component of the Community Earth System Model (CESM), version 1.1.1, and evaluates its impact on simulated climate. By ensuring consistency of the broadband surface longwave flux across different components of the CESM, the top-of-the-atmosphere (TOA) energy balance in the modified model can be attained without retuning the model. Inclusion of surface spectral emissivity, however, leads to a decrease of net upward longwave flux at the surface and a comparable increase of latent heat flux. Global-mean surface temperature difference between the modified and standard CESM simulation is 0.20 K for the fully coupled run and 0.45 K for the slab-ocean run. Noticeable surface temperature differences between the modified and standard CESM simulations are seen over the Sahara Desert and polar regions. Accordingly, the climatological mean sea ice fraction in the modified CESM simulation can be less than that in the standard CESM simulation by as much as 0.1 in some regions. When spectral emissivities of sea ice and open ocean surfaces are considered, the broadband LW sea ice emissivity feedback is estimated to be -0.003 W m-2 K-1, assuming flat ice emissivity as sea ice emissivity, and 0.002 W m-2 K-1, assuming coarse snow emissivity as sea ice emissivity, which are two orders of magnitude smaller than the surface albedo feedback. |
format |
Article in Journal/Newspaper |
author |
Huang, X Chen, X Flanner, M Yang, P Feldman, D Kuo, C |
author_facet |
Huang, X Chen, X Flanner, M Yang, P Feldman, D Kuo, C |
author_sort |
Huang, X |
title |
Improved representation of surface spectral emissivity in a global climate model and its impact on simulated climate |
title_short |
Improved representation of surface spectral emissivity in a global climate model and its impact on simulated climate |
title_full |
Improved representation of surface spectral emissivity in a global climate model and its impact on simulated climate |
title_fullStr |
Improved representation of surface spectral emissivity in a global climate model and its impact on simulated climate |
title_full_unstemmed |
Improved representation of surface spectral emissivity in a global climate model and its impact on simulated climate |
title_sort |
improved representation of surface spectral emissivity in a global climate model and its impact on simulated climate |
publisher |
eScholarship, University of California |
publishDate |
2018 |
url |
https://escholarship.org/uc/item/67m6d09d |
op_coverage |
3711 - 3727 |
genre |
Sea ice |
genre_facet |
Sea ice |
op_source |
Journal of Climate, vol 31, iss 9 |
op_relation |
qt67m6d09d https://escholarship.org/uc/item/67m6d09d |
op_rights |
public |
_version_ |
1766191393037877248 |