Long-term ozone trajectory climatology for the eastern US. Part 2: Results
- Vermont Dept. of Environmental Conservation, Waterbury, VT (United States)
This study has examined long-term, synoptic-scale meteorological flow conditions associated with high and low ozone concentrations at multiple locations throughout the Eastern United States. The work was originally conducted for, reported to, and guided by feedback from the Air Quality Analysis Workgroup of the Ozone Transport Assessment Group (OTAG) during 1996--1997. Several thousand backward air trajectories covering the summers of 1989 through 1995 were calculated for each of 23 regionally representative ozone monitoring stations distributed throughout the 37-state OTAG domain. Long-term associations between measured ozone concentrations and upwind airmass locations were evaluated in a probabilistic manner through application of residence-time analysis to the combined ozone and trajectory and ozone data for individual and multiple monitoring sites. While peak, short-term ozone levels are clearly influenced by local, surface meteorology and same-day, local precursor emissions, results from this study suggests that multi-day, synoptic-scale transport can also exert an important influence, through modifications to regional background concentrations. Air masses which enter the OTAG domain from external regions (to the north, south, east or west) are typically characterized by ozone concentrations at or near tropospheric background levels (30--40 ppb). Background levels increase substantially (by about 20 ppb) in air masses which have previously resided over central areas of the East, particularly the industrial Midwest. This centrally located source region appears to act as an important reservoir, subject to chronic accumulation of moderately high ozone concentrations, which are often subsequently transported to a wide range of surrounding receptor locations.
- OSTI ID:
- 362002
- Report Number(s):
- CONF-980632--
- Country of Publication:
- United States
- Language:
- English
Similar Records
The AQA workgroup summary: Telling the OTAG ozone story with data
Characterization of the ozone and transport conditions during the four OTAG episodes