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Abstract

Use of multi-frequency airborne radars have helped to evaluate the performance of satellite retrievals and further our understanding of ice microphysical properties. The dual-frequency ratio (DFR) derived from these radars is influenced by the size, density, and shape of particles, with higher values associated with larger particles which may have implications regarding snowfall at the surface.The Investigation of Microphysics and Precipitation for Atlantic Coast-Threatening Snowstorms (IMPACTS) is a three-year field campaign from winters 2020–2023 that combines in-situ and remote sensing measurements from two aircraft aimed at understanding the mechanisms associated with snowbands within mid-latitude cyclones. Coordination between the aircraft allows for evaluation of DFR measurements and provides insight into the particle size distribution behavior and hydrometeor habits observed within these enhanced DFR regions.Regions of prominently higher Ku- and Ka-band DFR at the in-situ aircraft location were distinguished using a novel technique for all coordinated flights during IMPACTS. Results from the 2020 and 2022 deployments indicate that within regions of enhanced DFR, the mass-weighted mean diameter was 60% larger, the effective density 33% smaller, and the normalized intercept parameter 79% lower than the other periods. Findings from the ongoing 2023 deployment aim to bring closure in understanding the microphysical properties within these higher DFR regions. Lastly, a neural network radar retrieval is used to investigate the 2D structure of microphysical properties associated with the larger DFR signatures and provides the spatial context for inferring certain microphysical processes such as aggregation.