Distinct surface response to black carbon aerosols

Tao Tang, Drew Shindell, Yuqiang Zhang, Apostolos Voulgarakis, Jean Francois Lamarque, Gunnar Myhre, Gregory Faluvegi, Bjørn H. Samset, Timothy Andrews, Dirk Olivié, Toshihiko Takemura, Xuhui Lee

研究成果: Contribution to journalArticle査読

抄録

For the radiative impact of individual climate forcings, most previous studies focused on the global mean values at the top of the atmosphere (TOA), and less attention has been paid to surface processes, especially for black carbon (BC) aerosols. In this study, the surface radiative responses to five different forcing agents were analyzed by using idealized model simulations. Our analyses reveal that for greenhouse gases, solar irradiance, and scattering aerosols, the surface temperature changes are mainly dictated by the changes of surface radiative heating, but for BC, surface energy redistribution between different components plays a more crucial role. Globally, when a unit BC forcing is imposed at TOA, the net shortwave radiation at the surface decreases by-5.87±0.67Wm-2(Wm-2)-1 (averaged over global land without Antarctica), which is partially offset by increased downward longwave radiation (2.32±0.38Wm-2(Wm-2)-1 from the warmer atmosphere, causing a net decrease in the incoming downward surface radiation of-3.56±0.60Wm-2(Wm-2)-1. Despite a reduction in the downward radiation energy, the surface air temperature still increases by 0.25±0.08K because of less efficient energy dissipation, manifested by reduced surface sensible (-2.88±0.43Wm-2(Wm-2)-1) and latent heat flux (-1.54±0.27Wm-2(Wm-2)-1), as well as a decrease in Bowen ratio (-0.20±0.07(Wm-2)-1). Such reductions of turbulent fluxes can be largely explained by enhanced air stability (0.07±0.02K(Wm-2)-1), measured as the difference of the potential temperature between 925hPa and surface, and reduced surface wind speed (-0.05±0.01ms-1(Wm-2)-1). The enhanced stability is due to the faster atmospheric warming relative to the surface, whereas the reduced wind speed can be partially explained by enhanced stability and reduced Equator-to-pole atmospheric temperature gradient. These rapid adjustments under BC forcing occur in the lower atmosphere and propagate downward to influence the surface energy redistribution and thus surface temperature response, which is not observed under greenhouse gases or scattering aerosols. Our study provides new insights into the impact of absorbing aerosols on surface energy balance and surface temperature response.

本文言語英語
ページ(範囲)13797-13809
ページ数13
ジャーナルAtmospheric Chemistry and Physics
21
18
DOI
出版ステータス出版済み - 9 17 2021

All Science Journal Classification (ASJC) codes

  • 大気科学

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