Evaluation of a new lightning-produced NO_x parameterization for cloud resolving models and its associated uncertainties

Christelle Barthe (1) , M. C. Barth (1)

1 NCAR - National Center for Atmospheric Research [Boulder]

A new parameterization of the lightning-produced NO_x 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-NO_x source and the number of moles produced per flash.

Domaines: Océan, Atmosphère

Christelle Barthe, M. C. Barth. Evaluation of a new lightning-produced NO_x parameterization for cloud resolving models and its associated uncertainties. Atmospheric Chemistry and Physics Discussions, 2008, 8 (2), pp.6603-6651. ⟨hal-00304075⟩