Collaborative Research: Understanding Relationships between First Lightning, In-cloud Microphysics and Satellite-Observed Cumulus Cloud-top Properties

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This research focuses on enhancing understanding of the inter-relationships between the Geostationary Operational Environmental Satellite (GOES) and Moderate Resolution Imaging Spectroradiometer (MODIS) satellite observations, total lightning information, and polarimetric radar fields related to the mechanisms that initiate lightning within convective clouds (so-called first lightning). A hypothesis to be tested is that one can estimate the onset, intensity and character of lightning events (i.e. the relative amount of lightning expected, in terms of flash rates over time) in convective clouds across a region. Lightning within convective clouds is far from ubiquitous, and therefore considerable uncertainty exists as to why certain storms are prolific lightning producers, while others nearby may not be. The project goals are: (1) Perform basic research to relate GOES satellite-observed (infrared) convective cloud growth properties to the character (intra-cloud versus cloud-to-ground) and intensity of lightning in these clouds, and to the relationship to in-cloud dual-polarimetric Doppler radar-observed microphysical distributions; (2) Enhance understanding of convective regimes by describing the general characteristics of lightning and convective cloud development as observed by satellite and dual-polarimetric Doppler radar in various environments; (3) Extend current ability to nowcast (0-90 minutes) lightning events using GOES and MODIS. Intellectual Merit: The research will lead to an improved understanding of the interrelationships between lightning, cloud microphysics, and of satellite observations of growing cumulus. This research will take advantage of an exiting meteorological testbed that includes dual-polarimetric radar, lightning mapping array, GOES, MODIS and Tropical Rainfall Measuring Mission (TRMM) observations, and a mobile radar. Density of lightning will be correlated in space and time to graupel, freezing altitudes and ice distributions (all inferred from polarimetric radar), and compared to GOES cloud-top cooling rates as an estimate of in-cloud vertical mass flux, cumulus cloud growth, and cloud-top microphysics. Insights into cumulus cloud electrification, recharge, and lightning types will be subsequently developed from this research. Broader Impact: A current CI forecasting technique developed by the Principal Investigators is already being evaluated within the Federal Aviation Administration's Aviation Weather Research Program and the National Weather Service. The mechanisms, therefore, are in place for this research to immediately impact a broad operational community. In addition, collaboration with other university scientists and graduate students will further extend this research to the larger academic and educational community.