Investigating the relationship between turbulence and lightning

Abstract:

Thunderstorms commonly produce turbulent airflows, which can have important implications for cloud structure and evolution, the transport of chemical species, and the safety of aircraft. Recent studies have indicated that turbulence also may control lightning characteristics, such as flash rate and size. Moreover, there are indications that the onset of lightning may be related to rapid intensification of turbulence within a growing convective storm. This observation is consistent with the known good empirical correlation between eddy dissipation rate (EDR, a measure of the strength of turbulence) and updraft strength. An algorithm to estimate EDR for in-cloud turbulence from Doppler radar data has been incorporated into open source software developed at NASA. This software (called the Python Turbulence Detection Algorithm, or PyTDA), which can be applied to data from almost any Doppler radar, is in the process of being validated against in situ measurements , as well as compared with other turbulence algorithms. Early validation results will be reported in this presentation. Then, the application of the turbulence retrievals to specific thunderstorm case studies, which have available Doppler radar and lightning mapping array (LMA) data, will be reported. Specific inquiries that will be addressed will include relationships between lightning onset and turbulence, relationships between flash rate/size and turbulence, the ability of turbulence retrievals to serve as proxies for updraft strength/location, and the implications of all these relationships for satellite-based lightning observations.