Aerosol effect on cloud droplet size as monitored from surface-based remote sensing over East China Sea region

The effect of increased aerosol concentrations on the low-level, non-precipitating, ice-free stratus clouds is examined using a suite of surface-based remote sensing systems. Cloud droplet effective radius and liquid water path are retrieved using cloud radar and microwave radiometer. Collocated measurements of aerosol scattering coefficient, size distribution and cloud condensation nuclei (CCN) concentrations were used to examine the response of cloud droplet size and optical thickness to increased CCN proxies. During the episodic events of increase in aerosol accumulation-mode volume distribution, the decrease in droplet size and increase in cloud optical thickness is observed. The indirect effect estimates are made for both droplet effective radius and cloud optical thickness for different liquid water path ranges and they range 0.02-0.18 and 0.005-0.154, respectively. Data are also categorized into thin and thick clouds based on cloud geometric thickness (Delta z) and estimates show IE values are relatively higher for thicker clouds. Citation: Pandithurai, G., T. Takamura, J. Yamaguchi, K. Miyagi, T. Takano, Y. Ishizaka, S. Dipu, and A. Shimizu (2009), Aerosol effect on cloud droplet size as monitored from surface-based remote sensing over East China Sea region, Geophys. Res. Lett., 36, L13805, doi: 10.1029/2009GL038451.