Effect of the droplet activation process on microphysical properties of warm clouds

Kentaroh Suzuki, Teruyuki Nakajima, Takashi Y Nakajima, Graeme L Stephens
2010 Environmental Research Letters  
This study investigates the effect of the droplet activation process on microphysical characteristics of warm clouds represented by correlation statistics between cloud droplet effective radius r e and cloud optical thickness τ c . The conceptual adiabatic model is first employed to interpret satellite-observed r e -τ c correlation statistics over two different regions and to reveal distinctively different increasing patterns of droplet number concentration between these regions. This
more » ... is attributed to a different behavior of the droplet activation process induced by differing microphysical conditions of aerosols. Numerical experiments of changing aerosol size spectrum are then performed with a spectral bin microphysics cloud model. The results show that the slope of the size spectrum controls the r e -τ c relationship through its effect on increasing pattern of droplet number concentration due to the activation process. The simulated results are also found to reproduce the r e -τ c correlation statistics closely resembling those observed when the slope parameter and the aerosol amount are appropriately chosen. These results suggest that the r e -τ c correlation statistics observed by remote sensing studies contains a signature of how the droplet activation process takes place in the real clouds.
doi:10.1088/1748-9326/5/2/024012 fatcat:kkmpdbutg5d4zotpfkp3brnmvm