Experience in applying the Alpert-Stein factor separation methodology to assessing urban land-use and aerosol impacts on precipitation

In this chapter, Alpert–Stein Factor Separation (FS) Methodology is used to assess the significance of various land surface characteristics on the development and precipitation characteristics of convective storms occurring downwind of an urban region. In particular, the roles of topography, momentum fluxes, radiative heat fluxes, and latent and sensible heat fluxes are evaluated. The use of this technique in investigating the relative and interactive roles of different nucleating aerosols, including cloud condensation nuclei, giant cloud condensation nuclei, and ice nuclei, on the development, structure, and precipitation processes of tropical convection is also then described. Numerical mesoscale simulations of urban enhanced convection Introduction We briefly review the application of a three-dimensional, cloud-resolving, mesoscale model case study described in Rozoff et al. (2003) to the examination of the impacts of St. Louis, MO, USA, land use and topography on local convective storms. Located within a relatively moist and temperate climate, St. Louis is an ideal city for experimental study since it is relatively isolated from other substantial urban areas and its local geography is devoid of major topography and large bodies of water. Furthermore, St. Louis was the site for a large field campaign in 1971–5, called Project METROMEX (Changnon et al., 1981). That study was dedicated to questions regarding the role of urban areas on weather modification. It is believed the findings for St. Louis are widely applicable to other cities containing similar background conditions.