Publication Date:
2015-07-22
Description:
It is well established that smoke particles modify clouds, which in turn affects climate. However, no studies have quantified the temporal dynamics of aerosol-cloud interactions with direct observations. Here, for the first time, we use temporally-offset satellite observations from northern Africa between 2006 and 2010 to quantitatively measure the effect of fire aerosols on convective cloud dynamics. We attribute a reduction in cloud fraction during periods of high aerosol optical depths to a smoke-driven inhibition of convection. We find that higher smoke burdens limit upward vertical motion, increase surface pressure, and increase low-level divergence—meteorological indicators of convective suppression. These results are corroborated by climate simulations that show a smoke-driven increase in regionally averaged shortwave tropospheric heating and decrease in convective precipitation during the fire season. Our results suggest that, in tropical regions, anthropogenic fire initiates a positive feedback loop where increased aerosol emissions limit convection, dry the surface and enable increased fire activity via human ignition.
Print ISSN:
0094-8276
Electronic ISSN:
1944-8007
Topics:
Geosciences
,
Physics
