UMD AOSC Seminar

The Effects of Deep Convection on Atmospheric Chemistry

Dr. Kenneth Pickering
Ph.D., Meteorology, University of Maryland

NASA GSFC Atmospheric Chemistry and Dynamics Branch
UMD Atmospheric and Oceanic Sciecne

This presentation will trace the important research developments of the last 25 years in defining the roles of deep convection in tropospheric chemistry.  The role of deep convection in vertically redistributing trace gases was first verified through field experiments conducted in 1985.  The consequences of deep convection have been noted in many other field programs conducted in subsequent years, and these will be briefly reviewed.  Modeling efforts predicted that deep convection occurring over polluted continental regions would cause downstream enhancements in photochemical ozone production in the middle and upper troposphere due to the vertical redistribution of ozone precursors.  Particularly large post-convective enhancements of ozone production were estimated for convection occurring over regions of pollution from biomass burning and urban areas.  These estimates were verified by measurements taken downstream of biomass burning regions of South America.  Models also indicate that convective transport of pristine marine boundary layer air causes decreases in ozone production rates in the upper troposphere and that convective downdrafts bring ozone into the boundary layer where it can be destroyed more rapidly.  Additional consequences of deep convection are perturbation of photolysis rates, effective wet scavenging of soluble species, nucleation of new particles in convective outflow, and the potential for stratosphere-troposphere exchange in thunderstorm anvils.  The remainder of the talk will focus on production of NO by lightning, its subsequent transport within convective clouds, and its effects on downwind ozone production.  Recent applications of cloud/chemistry model simulations combined with anvil NO and lightning flash observations in estimating NO production per flash will be described.  These cloud-resolving case-study simulations of convective transport and lightning NO production in different environments have yielded results which are directly applicable to the design of lightning parameterizations for regional and global chemical transport models.  The talk will conclude with an overview of two major convective transport and lightning NO field experiments planned for 2012.

November 18, 2010, Thursday

Reception: 3:00pm (Everyone Welcome)
Seminar: 3:30-4:30pm

Computer and Space Sciences (CSS) Building, Auditorium (Room 2400)
Refreshment is served at 3:00pm in the adjoining Atrium

[Contact: Dr. Russ Dickerson]
[AOSC | Seminar | Directions | Parking]

AOSC 818. Frontiers in Atmosphere, Ocean, Climate, and Synoptic Meteorology Research