May 10, 2012
Journal Article

Potential Aerosol Indirect Effects on Atmospheric Circulation and Radiative Forcing through Deep Convection

Abstract

Aerosol indirect effects, i.e., the interactions of aerosols with clouds by serving as cloud condensation nuclei (CCN) or ice nuclei (IN), constitute the largest uncertainty in climate forcing and projection. Previous IPCC reported aerosol indirect forcing is negative, which does not account for aerosol-convective cloud interactions because the complex processes involved are poorly understood and represented in climate models. Here we report that aerosol indirect effect on deep convective cloud systems can lead to enhanced regional convergence and a strong top-of atmosphere (TOA) warming. Aerosol invigoration effect on convection can result in a strong radiative warming in the atmosphere (+5.6 W m-2) due to strong night-time warming, a lofted latent heating, and a reduced diurnal temperature difference, all of which could remarkably impact regional circulation and modify weather systems. We further elucidated how aerosols change convective intensity, diabatic heating, and regional circulation under different environmental conditions and concluded that wind shear and cloud base temperature play key roles in determining the significance of aerosol invigoration effect for convective systems.

Revised: June 11, 2012 | Published: May 10, 2012

Citation

Fan J., D. Rosenfeld, Y. Ding, L.R. Leung, and Z. Li. 2012. "Potential Aerosol Indirect Effects on Atmospheric Circulation and Radiative Forcing through Deep Convection." Geophysical Research Letters 39. PNNL-SA-85127. doi:10.1029/2012GL051851