%0 Journal Article
%T Impacts of Aerosol Particle Size Distribution and Land Cover Land Use on Precipitation in a Coastal Urban Environment Using a Cloud-Resolving Mesoscale Model
%A Nathan Hosannah
%A Jorge E. Gonzalez
%J Advances in Meteorology
%D 2014
%I Hindawi Publishing Corporation
%R 10.1155/2014/904571
%X Urban environments influence precipitation formation via response to dynamic effects, while aerosols are intrinsically necessary for rainfall formation; however, the partial contributions of each on urban coastal precipitation are not yet known. Here, the authors use aerosol particle size distributions derived from the NASA aerosol robotic network (AERONET) to estimate submicron cloud condensation nuclei (CCN) and supermicron CCN (GCCN) for ingestion in the regional atmospheric modeling system (RAMS). High resolution land data from the National Land Cover Database (NLCD) were assimilated into RAMS to provide modern land cover and land use (LCLU). The first two of eight total simulations were month long runs for July 2007, one with constant PSD values and the second with AERONET PSDs updated at times consistent with observations. The third and fourth runs mirrored the first two simulations for ¡°No City¡± LCLU. Four more runs addressed a one-day precipitation event under City and No City LCLU, and two different PSD conditions. Results suggest that LCLU provides the dominant forcing for urban precipitation, affecting precipitation rates, rainfall amounts, and spatial precipitation patterns. PSD then acts to modify cloud physics. Also, precipitation forecasting was significantly improved under observed PSD and current LCLU conditions. 1. Introduction Many studies present clear evidence that cities influence regional weather via modification of synoptic fronts, urban heat island (UHI) generation [1¨C6], surface-atmosphere interactions that impact surface heat and moisture fluxes [7], building barrier effects [8], and increased aerosol concentrations [9]. Sinha Ray and Srivastava [10] showed that the rapidly urbanizing Indian landscape experienced precipitation increases in several urban locations (>70£¿mm/day) during the summer monsoon season over the last 100 years, coincident with an increase in extreme rainfall frequency (>120£¿mm/day). Analysis of historical precipitation records for Phoenix, AZ, revealed statistically significant increases in mean precipitation of 12¨C14% during the monsoon season from a preurban (1895¨C1949) to posturban (1950¨C2003) period in suburbs northeast of the Phoenix metropolitan area [11]. Selover [12] showed that moving summer convective storms over Phoenix produced precipitation minimums over the city in conjunction with maximums in surrounding lateral and downwind locations. Shepherd et al. [13] showed that UHIs affect local and regional weather/temperature via increased energy demands for cooling, adjustment of local wind flows
%U http://www.hindawi.com/journals/amete/2014/904571/