HR: 0830h
AN: A51D-0703    [PDF]
TI: Surface Ozone Differences Between Appledore Island and Thompson Farm: Local-Scale vs. Synoptic Scale Meteorology
AU: * Darby, L S
EM: lisa.darby@noaa.gov
AF: Environmental Technology Laboratory, NOAA, R/ET2 325 Broadway, Boulder, CO 80305 United States
AU: Senff, C J
EM: christoph.senff@noaa.gov
AF: Cooperative Institute for Research in the Environmental Sciences, University of Colorado, C/O NOAA R/ET2 325 Broadway, Boulder, CO 80305 United States
AB: At NEAQS 2002, the surface O$_{3}$ observation network included stations at Thompson Farm (TF), near Durham, NH, and Appledore Island (AI), just off the coast of NH. The stations were only $~$30 km apart, yet the differences in the O$_{3}$ measured at the two sites could be as high as 50 ppbv. This study focuses on meteorological processes contributing to the differences in O$_{3}$ at the two sites. During the first 6 days of Aug. 2002, the differences in surface O$_{3}$ measured at AI and TF ranged from $<$ 5 ppbv to $>$ than 50 ppbv, with AI typically having higher O$_{3}$ than TF. Meteorology played a role in these differences. For instance, on 6 Aug., a day when the ozone differences between the two sites were very small throughout the day ($< $10 ppbv), there were no local-scale circulations such as a sea breeze, and both TF and AI were in the same post-frontal northwesterly, `clean' (low-O$_{3}$) air. In contrast, on two of the days with large differences in surface ozone between the stations, there was a synoptic stationary front hugging the New England coast, separating the marine air mass (sampled at AI) from the continental air mass (sampled at TF). Differences in large-scale ozone transport within these two air masses led to much higher ozone values at AI than at TF, with differences as large as 50 ppbv. The formation and inland propagation of a sea breeze, measured by the ETL Doppler lidar, acted to lessen the effect of the stationary front on a local scale, bringing higher-ozone air to TF, reducing the difference in ozone between the two sites. Other features receiving further investigation will include the Appalachian Trough and the few times during which TF ozone measurements exceeded those at AI. The Appalachian Trough enhances the southwest transport of pollutants from the New York and Boston areas to the NH and ME coasts. This feature was in place from late in the day on 4 Aug. and continued through 5 Aug. During this period, ozone measurements at both sites were elevated relative to the other days investigated. TF had ozone measurements that exceeded those at AI only during brief periods on five of the six days analyzed. These periods tended to be, but were not exclusive to, the hours between 1200 and 1500 LST.
DE: 0325 Evolution of the atmosphere
DE: 0345 Pollution--urban and regional (0305)
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting