Open AccessAircraft vertical profiles of trace gas and aerosol pollution over the mid‐Atlantic United States: Statistics and meteorological cluster analysis
Author(s) -
Taubman B. F.,
Hains J. C.,
Thompson A. M.,
Marufu L. T.,
Doddridge B. G.,
Stehr J. W.,
Piety C. A.,
Dickerson R. R.
Publication year - 2006
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2005jd006196
Subject(s) - angstrom exponent , aerosol , environmental science , atmospheric sciences , troposphere , single scattering albedo , altitude (triangle) , pollution , climatology , boundary layer , planetary boundary layer , air mass (solar energy) , meteorology , geology , geography , physics , turbulence , ecology , geometry , mathematics , biology , thermodynamics
From 1997 to 2003, airborne measurements of O 3 , CO, SO 2 , and aerosol properties were made during summertime air pollution episodes over the mid‐Atlantic United States (34.7–44.6°N, 68.4–81.6°W) as part of the Regional Atmospheric Measurement, Modeling, and Prediction Program (RAMMPP). Little diurnal variation was identified in the CO, SO 2 , and Ångström exponent profiles, although the Ångström exponent profiles decreased with altitude. Boundary layer O 3 was greater in the afternoon, while lower free tropospheric O 3 was invariant at ∼55 ppbv. The single scattering albedo increased from morning to afternoon (0.93 ± 0.01–0.94 ± 0.01); however, both profiles decreased with altitude. A cluster analysis of back trajectories in conjunction with the vertical profile data was used to identify source regions and characteristic transport patterns during summertime pollution episodes. When the greatest trajectory density lay over the northern Ohio River Valley, the result was large O 3 values, large SO 2 /CO ratios, highly scattering particles, and large aerosol optical depths. Maximum trajectory density over the southern Ohio River Valley resulted in little pollution. The greatest afternoon O 3 values occurred during periods of stagnation. North‐northwesterly and northerly flow brought the least pollution overall. The contribution of regional transport to afternoon boundary layer O 3 was quantified. When the greatest cluster trajectory density lay over the Ohio River Valley (∼59% of the profiles), transport accounted for 69–82% of the afternoon boundary layer O 3 . Under stagnant conditions (∼27% of the profiles), transport only accounted for 58% of the afternoon boundary layer O 3 . The results from this study provide a description of regional chemical and transport processes that will be valuable to investigators from the Baltimore, New York, and Pittsburgh EPA Supersites.