Showing papers by "James Walega published in 1987"
TL;DR: A series of flights based at Springfield, Ohio, extending from the Gulf of Mexico to upstate New York, and from the surface to 3.5 km, were flown in air having a predominantly southerly origin this article.
Abstract: We report gas phase measurements of hydrogen peroxide, sulfur dioxide and ozone in the lower troposphere over the eastern United States in October and November 1984. A series of flights based at Springfield, Ohio, extending from the Gulf of Mexico to upstate New York, and from the surface to 3.5 km, were flown in air having a predominantly southerly origin. Occasionally, air of northwesterly origin and of local stagnation was sampled. Flights occurred between 0800 and 2000 EST on 10 different days. Gas phase H2O2 concentrations ranged from between the detection limit (nominally 0.2 ppbv at S/N = 3) to 4.1 ppbv. In general, air near the surface contained substantially less H2O2 than air aloft. Maximum H2O2 concentrations were observed just above cloud tops. A latitudinal H2O2 gradient existed in air near the surface and in air above cloud top with higher concentrations in the south. This gradient was absent at higher altitudes (>3.0 km). SO2 concentrations ranged from the detection limit (nominally 1 ppbv at S/N = 3) to 50 ppbv, were typically between 5 and 10 ppbv in surface air and were less than 2 ppbv aloft. Ozone concentrations were typically 35±10 ppbv, ranged from 11 to 57 ppbv and showed no trend with altitude. The H2O2 measurements were the first of their kind above the surface and have several implications for acid deposition and tropospheric chemistry research. We observed an inverse relationship between H2O2 and SO2, evidence for the long-range transport of H2O2 from southern latitudes, and no discernable relationship between O3 and H2O2 concentrations. Observation near cloud suggested that mixing of H2O2 from above with SO2 from below could be the controlling process in converting SO2 to SO42− in cloud.
132 citations