Tropical tropospheric-only responses to absorbing aerosols

Geeta G. Persad, Yi Ming, V. Ramaswamy

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

Absorbing aerosols affect the earth's climate through direct radiative heating of the troposphere. This study analyzes the tropical tropospheric-only response to a globally uniform increase in black carbon, simulated with an atmospheric general circulation model, to gain insight into the interactions that determine the radiative flux perturbation. Over the convective regions, heating in the free troposphere hinders the vertical development of deep cumulus clouds, resulting in the detrainment of more cloudy air into the large-scale environment and stronger cloud reflection. A different mechanism operates over the subsidence regions, where heating near the boundary layer top causes a substantial reduction in low cloud amount thermodynamically by decreasing relative humidity and dynamically by lowering cloud top. These findings, which align well with previous general circulation model and large-eddy simulation calculations for black carbon, provide physically based explanations for the main characteristics of the tropical tropospheric adjustment. The implications for quantifying the climate perturbation posed by absorbing aerosols are discussed.

Original languageEnglish (US)
Pages (from-to)2471-2480
Number of pages10
JournalJournal of Climate
Volume25
Issue number7
DOIs
StatePublished - Apr 2012
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Atmospheric Science

Keywords

  • Aerosols
  • Climate models
  • Cloud forcing
  • Cloud parameterizations
  • Clouds
  • Radiative forcing

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