Microbursts are a rapidly evolving, vertically oriented meteorological phenomena that can be extremely hazardous to aviation, and other human activities, if left undetected. The temporal resolution and vertical sampling of the current operational weather radar network (NEXRAD) is too coarse to properly observe the evolution of microbursts and their precursor signatures. However, a potential polarimetric phased array weather radar (PAR) should be able to improve both temporal resolution and spatial sampling of the atmosphere to provide better observation of rapidly evolving hazards such as microbursts. All-digital PAR technology is extremely flexible as a wide array of scanning techniques are available to use; however, this flexibility is not without trade-offs, and these trade-offs are important for understanding how a potential PAR network would operate.
This thesis will lay out a framework and tool set for the study of microbursts and their precursor signatures with varying PAR scanning strategies. This project is the first of its kind to investigate the question of what trade-offs are associated with different scanning strategies when using a planar, mechanically rotating, all-digital PAR to observe and detect microbursts and their precursor signatures, including dual-polarization variables. The scanning strategies analyzed include a traditional volume coverage pattern (VCP) 212, a true range-height indicator (RHI) scan, and imaging at three different spoiled beamwidths in elevation. VCP 212 represents the current operational capacity for microburst observation and detection. True RHI scanning and imaging are more feasible on a PAR system, and they can provide faster temporal resolution and finer vertical sampling.
The framework and tools developed herein are tested in a proof-of-concept analysis by looking at a single wet microburst producing storm generated within a numerical weather prediction (NWP) simulation. Using this NWP simulation data, scanning strategies are implemented through the use of a radar emulator, RSim. These emulations are then analyzed both qualitatively and quantitatively to compare the size, shape, and intensity observations of different microburst precursor signatures: descending reflectivity columns (DRCs), specific differential phase (KDP) cores, and mid-level convergence. Because of
the use of NWP simulations, error analysis is also performed to characterize the impact of estimation errors. The results of this test case analysis of one wet microburst imply that, when utilizing imaging, there is a limit to the benefits provided by increased temporal resolution. This limit occurs at temporal resolutions equal to 30 s and an imaging spoil factor of 5 degrees. When utilizing any spoil factor larger than 5 degrees , the effects of data degradation become too great for the scanning strategy to overcome, the representativeness of the model environment is degraded, and estimation errors become large. However, these results can only be considered preliminary because the analysis only serves as a proof-of-concept
