Aerosol impacts on warm-cloud microphysics and drizzle in a moderately polluted environment

Quantitatively, aerosol-cloud interactions (ACI = partial derivative lnCER/partial derivative ln alpha \(CWP), changes in CER relative to changes in aerosol amounts) were 0.07 for our research domain and varied between 0.09 and 0.06 in the surrounding remote (i.e., ocean) and polluted (i.e., land) areas, respectively, indicating aerosol indirect effects were stronger in the remote area. From the raindrop size distribution analysis, high aerosol loading resulted in a decreased frequency of drizzle events, redistribution of cloud water to more numerous and smaller droplets, and reduced collision-coalescence rates.

However, during light rain (<= 1 mm h(-1)), high aerosol concentrations drove raindrops towards smaller droplet sizes and increased the appearance of drizzle drops. This study used long-term surface and satellite data to determine aerosol variations in northern Taiwan, effects on clouds and precipitation, and observational strategies for future research on aerosol-cloud-precipitation interactions.