The influence of the growth of the Dallas/Fort Worth (DFW) Metroplex on regional precipitation patterns

摘要

Due to the effects urbanization has on land-use and land cover change (LULC),urban areas have a major influence on the environment. The strong coupling between theland and atmosphere can alter the microclimatology of cities and their surroundingregions. Previous research has shown that cities can influence regional precipitationpatterns. This is a result of many factors such as: increased heating and lifting caused bythe urban heat island effect (UHI), increased pollution and aerosols, alteration of landuse/land cover (which includes surface albedo, presence or lack of vegetation, andsurface roughness changes), and urban design (which leads to increased friction andconvergence). This study analyzes temporal and regional changes in the precipitationpatterns of the Dallas/Fort Worth Metroplex as it has grown over the past century, andprovides a methodology for testing urban influences on precipitation in othermetropolitan areas.Precipitation from 1930 ? 2007 was analyzed for the following three studyregions: DFW (urban area), CRA (upwind control region), and CRB (downwind controlregion). By comparing early (1930 ? 1950) and late period (1987 ? 2007) precipitationwithin each region, it was found that there were no statistically significant differences between the two periods. Entire period precipitation (1930 ? 2007) at CRB wasstatistically significantly different from both DFW and CRA although early and lateperiod precipitation was not. While precipitation was similar between the two periods inall regions, comparing precipitation between the regions using the entire period showspotential anthropogenic influences. Land cover change between 1976 and 2001 wasanalyzed and it was found that water in the DFW Metroplex study region increased by54.75%, vegetation decreased by 20.34%, and urban land cover increased by 176.14%.This may increase atmospheric moisture, surface temperature, friction and lifting over theurban center, and decrease the amount of heat released from the ground. While naturalclimate variability is the most important factor influencing precipitation in this region, itis possible that urbanization is also changing local and regional precipitation patterns, itmay not be the only factor influencing change.