Improving Microburst Detection and Warning with Polarimetric Weather Radar

A microburst (also downburst) is an intense small-scale downdraft, resulting in strong divergent wind near the surface. It is usually classified with two categories: dry microburst and wet microburst. Both types of microbursts could cause severe wind hazard and are known to be particularly dangerous for aviation activities. Currently, the operational microburst algorithms available in the weather radar community are legacy algorithms of the Doppler era, which focus on the detection of divergent wind patterns when a microburst occurs. The detection might result in false alarms due to the quality of velocity data and the limitation of the velocity model. Moreover, it is usually too late when the radar observes the microburst pattern, in terms of issuing warnings. Accurate nowcasting and detection of a microburst is highly desirable for aviation safety.

Currently, weather radar has advanced into the polarimetric era. Recent research have revealed that many polarimetric radar signatures could be associated with the early evolution and occurrence of a microburst, e.g., the specific differential phase (KDP) “column”, differential reflectivity (ZDR) “column” and “hole”, and correlation coefficient (ρ_hv) depression. Scientists from the National Severe Storms Laboratory (NSSL) have been working on the improvement of the radar microburst algorithm with Enterprise Electronics Corporation (EEC). The new algorithm applies the storm tracking technique to monitor the significant polarimetric radar signatures. It can provide the short-time (typically 10 minutes) nowcasting of a microburst and also enhances the detection performance as compared to the current detection algorithm of the Doppler version. The current study presents the proposed microburst algorithm and the testing results.