USA Springtime Ozone Pathways

Cooper O. R., et al. (2005), A springtime comparison of tropospheric ozone and transport pathways on the east and west coasts of the United States, J. Geophys. Res., 110, D05S90, doi:10.1029/2004JD005183. Full Text

A study is conducted to determine the influence of Asian pollution plumes on free tropospheric ozone above the west coast of the United States during spring, as well as the impact of North American emissions on east coast free tropospheric ozone. Ozonesonde profiles from four sites are used: Trinidad Head, CA, Huntsville, AL, Wallops Island, VA, and the MOZAIC site. Only in the lower layers did the three east coast sites (0-1 km layer for MOZAIC, 0-1 and 1-2 km layers for Wallops Island and Huntsville) have statistically significant greater ozone than the west coast site (Trinidad Head).

A particle dispersion model (FLEXPART) was used to determine the surface source regions for each case, and the amount of anthropogenic NOx tracer that would have been emitted into each air mass. The amount of NOx tracer emitted into the east coast profiles was much greater in the lower and mid troposphere than at the west coast; however, no significant difference was found in free tropospheric ozone between the east and west coasts of the United States during spring.

Figure 4. Mean ozone profiles for April–May at six locations in the United States. The MOZAIC data (Boston, New York City, and Philadelphia) represent the years 2000–2002, while the other locations represent 2000–2003. Data are reported every 500 m and represent 500 m layer averages.