NASA’s MSFC and UAHuntsville are collaborating with the 45th Weather Squadron (45WS) at Cape Canaveral Air Force Station (CCAFS) to enable improved nowcasting of lightning cessation. This project centers on use of dual-polarimetric radar capabilities, and in particular, the new C-band dual-polarimetric weather radar acquired by the 45WS.
While previous studies have developed statistically-based lightning cessation algorithms driven primarily by trending in the actual total lightning flash rate, we believe that dual-polarimetric radar variables offer the possibility to improve existing algorithms through the inclusion of physically meaningful trends reflecting interactions between in-cloud electric fields and ice-microphysics. Specifically, decades of polarimetric radar research using propagation differential phase has demonstrated the presence of distinct phase and ice crystal alignment signatures in the presence of strong electric fields associated with lightning. One question yet to be addressed is: To what extent can propagation phase-based ice-crystal alignment signatures be used to nowcast the cessation of lightning activity in a given storm? Accordingly, data from the UAHuntsville ARMOR radar along with the NASA-MSFC North Alabama Lightning Mapping Array are used in this study to investigate the radar signatures present before and after lightning cessation.
Tropical Cyclogenesis Applications
It has been hypothesized that intense, electrically-active convection may aid the process of tropical cyclogenesis through dynamic and thermodynamic feedbacks on the larger scale circulation. This part of the talk will include a discussion of the use of NCEP Reanalysis data and data from instruments aboard the Tropical Rainfall Measurement Mission (TRMM) to investigate the role that widespread and/or intense lightning-producing convection present in African easterly waves (AEWs) may play in tropical cyclogenesis over the Atlantic, Caribbean, and East Pacific.
Results suggest that, in general, over Africa and as waves that develop tropical cyclones near their region of development, they are associated with more widespread and/or more intense, lightning-producing convection compared to non-developing AEWs. In particular, significant differences between the lightning flash rate associated with developing and non-developing waves may suggest the potential use of lightning observations for the forecasting of tropical cyclogenesis from AEWs.
Brown Bag Seminar (1-19-11)