Atmos. Chem. Phys. Discuss., 8, 6603-6651, 2008
www.atmos-chem-phys-discuss.net/8/6603/2008/
doi:10.5194/acpd-8-6603-2008
© Author(s) 2008. This work is distributed
under the Creative Commons Attribution 3.0 License.
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Evaluation of a new lightning-produced NOx parameterization for cloud resolving models and its associated uncertainties
C. Barthe1,* and M. C. Barth1
1National Center for Atmospheric Research, Boulder, CO, USA
*now at: Laboratoire d'Aérologie, CNRS/Université Paul Sabatier, Toulouse, France

Abstract. A new parameterization of the lightning-produced NOx has been developed for cloud-resolving models. This parameterization is based on three unique characteristics. First, the cells that can produce lightning are identified using a vertical velocity threshold. Second, the flash rate in each cell is estimated from the non-precipitation and precipitation ice mass flux product. Third, the source location is filamentary instead of volumetric as in previous parameterizations.

This parameterization has been tested on the 10 July 1996 Stratospheric-Tropospheric Experiment: Radiation, Aerosols and Ozone (STERAO) storm. Comparisons of the simulated flash rate and NO mixing ratio with observations at different locations and stages of the storm show a good agreement. An individual flash produces on average 121±41 moles of NO (7.3±2.5×1025 molecules NO) for the simulated high cloud base, high shear storm. Sensitivity tests have been performed to study the impact of the flash rate, the cloud-to-ground flash ratio, the flash length, the spatial distribution of the NO molecules, and the production rate per flash on the NO concentration and distribution. Results show a strong impact from the flash rate, the spatial placement of the lightning-NOx source and the number of moles produced per flash.


Citation: Barthe, C. and Barth, M. C.: Evaluation of a new lightning-produced NOx parameterization for cloud resolving models and its associated uncertainties, Atmos. Chem. Phys. Discuss., 8, 6603-6651, doi:10.5194/acpd-8-6603-2008, 2008.
 
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