HR: 09:25h
AN: AE21A-08 INVITED     [Abstracts]
TI: Numerical Modeling of Nitric Oxide Production by Lightning
AU: * Helsdon, J H
EM: john.helsdon@sdsmt.edu
AF: Intstitute of Atmospheric Sciences, South Dakota School of Mines and Technology, 501 E. St. Joseph St., Rapid City, SD 57701 United States
AB: The production of nitric oxide (NO) by lightning remains the least well quantified of the various sources of NO in the atmosphere. NO, along with NO$_{2}$, are important in moderating the ozone budget of the troposphere. Since lightning-produced NO is created at mid-tropospheric levels and, subsequently, transported into the upper troposphere by thunderstorm airflows, it is able to interact with ozone directly, rather than having to be brought up from the surface where chemical lifetimes are shorter. Current estimates of the global annual source term for lightning-produced NO span an order of magnitude and need to be refined in order for more accurate incorporation into global chemical transport models. One method of refining these estimates is to better understand the NO production of individual thunderstorms through numerical modeling of the production and distribution of NO within such storms. We have employed our three-dimensional Storm Electrification Model (SEM) to study this problem by simulating the 10 July 1996 storm from the Stratospheric-Tropospheric Experiment: Radiation, Aerosols, and Ozone (STERAO) project. The explicit lightning scheme in the SEM allows the calculation of NO production based on the energy dissipated by each lightning flash, with the NO distributed along the generated lightning channel. Using data on lightning flash production and observed NO mixing ratios obtained during STERAO, we can directly compare the simulated NO concentrations with those observed to determine source amounts and distributions within the storm. In this talk, an overview of the methodology will be presented along with the latest results from this ongoing research.
DE: 3324 Lightning
DE: 3367 Theoretical modeling
DE: 3304 Atmospheric electricity
DE: 0320 Cloud physics and chemistry
DE: 0368 Troposphere--constituent transport and chemistry
SC: Atmospheric and Space Electricity [AE]
MN: 2004 AGU Fall Meeting