An Efficient Method for Analyzing PAR-Observed Tornadic Mesocyclones and Designing PAR Adaptive Scans

Previously, a computationally efficient two-dimensional variational method was developed to analyze the vortex wind fields of mesocyclones observed by operational WSR-88D radars for nowcast applications. In this method, the vortex wind field is retrieved in a nested domain over the mesocyclone area in a moving coordinate system co-centered the mesocyclone on the conical surface of the lowest sweep of radar scan. As the background error covariance is modeled with the desired vortex flow dependence, the method can retrieve the vortex winds of mesocyclones scanned from a single Doppler radar. To take the advantages provided by the rapid scans of phased array radar (PAR), the method is upgraded by including the advection equations of radar image pattern movements as additional constraints in the cost-function, so the method can use PAR observations from multiple consecutive time levels (instead of single individual time level) to extract additional information on vortex winds from image pattern movements. The detailed method will be presented at the conference with the results obtained by applying the method to PAR rapid scans of the EF5 tornadic mesocyclone that struck Moore in Oklahoma on 20 May 2013. The upgraded method can be also used with simulated PAR observations to design and optimize PAR adaptive scans of tornadic mesocyclones for retrieving the vortex winds. The experiment designs and preliminary results on this application will be also reported at the conference.