Surface and aircraft observations of ozone, NOy and hydrocarbons will be used to evaluate an Eulerian air chemistry model and to quantify the relative importance of chemical and meteorological processes associated with high ozone levels along the east coast of North America. Observations for this analysis will be taken from the North American Research Strategy for Tropospheric Ozone (NARSTO) 1995 Northeast field campaign.
A lumped hydrocarbon chemical mechanism within a reactive transport model will be used to describe the production and destruction of ozone and other trace gases for selected periods of the campaign. Four-dimensional data assimilation of the horizontal winds, potential temperature and specific humidity will be used to bring the meteorological fields into closer agreement with observations. Model performance will then be evaluated by comparing predicted and observed time series of various reactive species. Aircraft observations of ozone and NOy will be used to assess model performance in reproducing the chemical features above the surface layer. Our analysis will focus on days when the surface mixing ratio of ozone was significantly higher than the mixing ratios observed on preceding days.
Results will then be presented from a series of sensitivity tests to evaluate the relative importance of a variety of processes associated with these observations. Processes to be considered will include the height dependence of vertical diffusivities, the role of water vapor on oxidant production, and the relative importance of local (versus remote) emissions of NOx and hydrocarbons
Symposium on Interdisciplinary Issues in Atmospheric Chemistry