Kenneth Pickering (PI)
University of Maryland College Park
pickerin@atmos.umd.edu

Effects of Clouds, Convection, and Lightning on Tropospheric Chemistry in the GMI Model

We propose to continue supporting Global Modeling Initiative (GMI) CTM development and evaluation.  Our proposed efforts build upon GMI-related work we accomplished under past grants.  We will begin by extending the upward cloud mass flux based lightning flash rate parameterization we developed for GMI to new meteorological data sets being implemented into the GMI framework.  We will then use neural networks to develop a more accurate and physically-based lightning parameterization that uses multiple predictor variables.  We plan to assist the GMI team in the implementation of these schemes in the GMI model.  We also plan to continue evaluating parameterized convection in the GMI model.  Through comparison with ISCCP cloud data and a new MODIS-based cloud data set that contains layering information, we will evaluate the distribution and structure of clouds in the new meteorological data sets.  The impact of errors in cloud distribution and structure on photolysis and wet scavenging will be assessed through analysis of GMI model output from simulations driven by assimilated meteorology with and without the inclusion of the new MODIS-based cloud data.    Science questions concerning the impact of lightning versus anthropogenic NOx emissions on upper tropospheric chemical budgets will be addressed for each of the meteorological data sets used to drive the GMI CTM.  Radiative forcing due to upper tropospheric convectively-enhanced ozone will be assessed and the components of this forcing due to lightning and to anthropogenic NO emissions will be determined.

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