Article,
Measurements of OH, H2SO4, and MSA during Tropospheric Ozone Production About the Spring Equinox (TOPSE)
Journal of Geophysical Research-Atmospheres, 108 (D4): -- (February 2003)664PJ Times Cited:5 Cited References Count:34.
Abstract
1 Data from OH, H2SO4, and MSA measurements performed during Tropospheric Ozone Production About the Spring Equinox (TOPSE) are presented. Model simulations of OH results made at solar zenith angles of 60degrees or less showed a tendency of the model to overestimate OH concentrations. This overestimation was a factor of 1.7 at the lower latitudes (<57&DEG;N) of the study. At higher latitudes (>57degreesN) the model tended toward agreement and ultimately an underestimation of OH concentrations by a factor of 0.7. Comparisons of measurements and model showed the model underestimates OH concentrations at solar zenith angles greater than 70degrees. The results of the present study are discussed in the context of previous studies. Possible model discrepancies are discussed. Measurements of H2SO4 showed the highest concentrations at the lowest altitudes (<2000 m) and the lowest latitudes of the study. Larger H2SO4 concentrations observed at higher latitudes were accompanied at times by particle nucleation as indicated by the presence of UCN (ultra-fine condensation nuclei) with diameters of 3-4 nm. Concentrations of MSA were generally low with typical values of <2 x 10(5) molecule cm(-3). High concentrations (>10(7) molecule cm(-3)) were found in layers and were accompanied by other compounds such as NOx and NOy indicating MSA may also have an industrial source.
