Stratospheric Lightning Forecasting and Nowcasting Tools

Our ultimate goal is the design, test and deployment of a decision aid to minimize interactions of High Altitude Airships (HAAs) with thunderstorms producing intense electrodynamic disturbances in the lower stratosphere associated with tropospheric lightning-induced phenomena collectively known as Transient Luminous Events (TLEs). Evidence points to intense, transient electric fields, some with highly impulsive characteristics, and even lightning-like electrical discharges emerging from cloud tops, at HAA altitudes. Until the electrical environment can be properly quantified and vehicles appropriately hardened, avoidance of the parent storms appears a prudent policy. In Phase III, we would the make operational the software that would be incorporated into a field-deployable work station allowing HAA operators to reposition vehicles away from regions with forecasted electrical hazards within the upcoming 72 hours, plus identifying near-term storms producing TLEs (nowcasting). In order to deploy the SENTRIH system (pronounced "sentry"), for Stratospheric ENvironmental Thunderstorm-Related Interferences to HAAs, several technical challenges must be met: (1) diagnosing those storm types known to produce TLEs from operational numerical weather prediction models, (2) demonstrating real-time detection and location of sprite/elve producing lightning strokes using ELF/VLF signal transient analysis, and (3) determining an RF or meteorological signature for blue jet and giant jets.