Understanding the effects of aerosols on cloud microphysics in coastal urban environments

Several studies have found evidence of warm-season rainfall increases over and downwind of cities. This induced precipitation has been attributed mostly to induced updraft of warm air masses. Aerosols are abundant in urban environments and it has been hypothesized that they play a role in the water balance of cities. High concentrations of cloud condensation nuclei (CCN) may induce precipitation in humid urban environments. However, precipitation may also be reduced due to excess CCNs or by large aerosols. The present research is directed to improve our understanding of the role of aerosols in cloud processes of complex coastal urban environments through observations and numerical analysis. The role of aerosols in precipitation is investigated by numerical analysis of the microphysics of clouds by numerically representing the growth by condensation, collision, and coalescence. The particles growth into rain droplets is to be explored for characteristic aerosols distributions of coastal urban environments gathered from AERONET stations using the natural environment of New York City as the testing scenario. The case of the summer 2007 will be analyzed using observations and numerical analysis to discern local precipitation attributed to aerosols.