P1.6
Linking ground level ozone concentration, thermal landscape, and landcover characteristics: a case of intra-urban heterogeneity in Washington DC area
Ivan Cheung, George Washington University, Washington, DC
This paper attempts to explore the use of remotely sensed information obtained from Landsat 7 enhanced thematic mapper (ETM+) to evaluate intra-urban heterogeneity of ground level ozone concentration. Much research effort has largely focused upon the importance of synoptic scale, regional transport mechanisms in evaluating ground level ozone pollution episodes. Due to the high degree of heterogeneity in radiative, chemical, and even physical conditions of the built environment with the city, it is expected that ozone level may also vary substantially throughout the urban system. In the Washington DC area (with population over 890,000 and land area of 265 km2), there exists 5 ozone monitoring sites with highest daily maximum ozone level observed near the central business district. During the afternoon when ozone level is the highest, the city is dominated by southerly flow. Five corresponding upwind airsheds (between 135° and 225°) are constructed to examine the differences in landcover characteristics (measured by normalized difference vegetation difference and percent impervious surfaces), radiative characteristics (estimated from reflectance at the visible and near infrared wavelengths), and thermal conditions (estimated from thermal infrared wavelength) among the 5 locations. An earlier study showed that the 2 km upwind airshed of the near downtown location is characterized by a substantially higher percentage of impervious surfaces, lower NDVI, higher reflectance at the red spectrum and lower reflectance at the near infrared.
Poster Session 1, FLOW AND DISPERSION STUDIES
Wednesday, 22 May 2002, 3:00 PM-5:00 PM
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