Measurements of OH, H2SO4, and MSA during tropospheric Ozone production about the Spring Equinox (TOPSE)

R. L. Mauldin, C. A. Cantrell, Mark Andrew Zondlo, E. Kosciuch, B. A. Ridley, R. Weber, F. E. Eisele

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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 60° 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°N) of the study. At higher latitudes (>57°N) 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 70°. 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 × 105 molecule cm-3. High concentrations (>107 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.

Original languageEnglish (US)
Pages (from-to)14-11
Number of pages4
JournalJournal of Geophysical Research D: Atmospheres
Issue number4
StatePublished - Feb 27 2003

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Materials Chemistry
  • Polymers and Plastics
  • Physical and Theoretical Chemistry


  • HSO
  • Hydroxyl
  • MSA
  • OH
  • Sulfuric


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