88th Annual Meeting (20-24 January 2008)

Monday, 21 January 2008
The influence of urbanization on precipitation patterns in the Dallas/Fort Worth (DFW) Metroplex since 1900
Exhibit Hall B (Ernest N. Morial Convention Center)
Anna Marie Nordfelt, Texas A&M University, College Station, TX; and S. M. Quiring
Urbanization is an important agent of land-use/land cover change (LULC) and it has a major influence on the environment. Due to the strong coupling of the land and atmosphere, the microclimatology of urban areas and their surrounding regions are often significantly altered by urbanization. Recent research has found that spatial patterns of precipitation are influenced by urbanized areas, but the amount of precipitation in various regions has increased. It has been shown that there is a link between urban areas and increased precipitation because convective activity tends to increase downwind of these urban areas. There are many possible causes for these changes in precipitation. Factors that have an influence are the urban heat island effect (UHI), increased pollution and changes in aerosol sizes, alteration of land use/land cover (which includes surface albedo, presence or lack of vegetation, and surface roughness changes), and general urban design.

This study identifies that nature of the spatial and temporal changes in regional precipitation patterns and explores how these changes are related to urban LULC. It takes into account the Dallas/Fort Worth Metroplex and the surrounding counties, as the climatic effects of an urban area extend to their surrounding regions. Since their establishment, the DFW Metroplex has grown in size, population, and dramatically altered the LULC as a result. It is hypothesized that the long-term growth of DFW since the early 20th century and the associated LULC changes have significantly altered regional precipitation patterns. My analysis is based on warm-season convective events, as these are the events found to be most affected. Precipitation data within and throughout the study region was collected from 1893 to the present. In addition to a temporal analysis of this data, a spatial analysis was conducted to determine how regional patterns of precipitation have varied in response to increases in urbanization.

Preliminary analysis has shown that precipitation regions do vary as a function of their location relative to the metroplex. It was found that not only will the total amount of regional precipitation increase, but also regional precipitation will fluctuate considerably on a decadal (or longer/shorter) time period due to natural climatic variations. It was also determined that spatial precipitation patterns have changed throughout the study period. This study not only shows how strong an influence urbanization can be on a regional climate, but it also provides a methodology that can be transferred to other metropolitan regions in future research.

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