Micro- and Mesoscale Structures within Snowbands in Winter Storms: Preliminary Results from the Inestigation of Microphysics and Precipitation for Atlantic Coast Threatening Snowstorms (IMPACTS) Field Campaign

Winter snowstorms have large societal impacts causing travel disruptions and school and business closures. Snowfall within individual storms is not evenly distributed, but is often organized in banded structures of higher intensity snowfall manifested as regions of local maxima in radar reflectivity. The processes that contribute to the organization, evolution and life cycle of these snowbands are not well understood. In order to address this knowledge gap, the NASA Earth Venture Suborbital-3 Investigation of Microphysics and Precipitation for Atlantic Coast-Threatening Snowstorms (IMPACTS) field campaign collected measurements within snowstorms that occurred in the Northeast and upper Midwest regions of the United States and Canada across three winter seasons, from 2020 through 2023. The goals of IMPACTS are to characterize the structure and evolution of a range of snowbands, explore the dynamical, thermodynamical, and microphysical processes contributing to snowband structures, and improve remote sensing and modeling of snowfall. Over 35 individual storm systems across the three seasons were sampled by aircraft and ground assets. The aircraft included the satellite-simulating high-altitude ER-2 and the in-situ P-3 aircraft that flew at varying altitudes. The ER-2 was equipped with radars sampling cloud and precipitation characteristics at four frequencies (X-, Ku-, Ka-, and W-band), 2 radiometers measuring radiances across microwave and sub-millimeter wavelengths, a cloud physics lidar, and a lightning detection system. The P-3 was equipped with multiple cloud microphysics probes, instruments measuring flight-level environmental parameters such as temperature, humidity and wind, and a dropsonde system. Ground systems included mobile and fixed radar systems, sounding teams, and the New York Mesonet surface data. These data are supplemented with operational data such as National Weather Service surface observations, soundings at fixed sites, and GOES-16 satellite data. Together these data paint a picture of cloud and precipitation structure and evolution across a wide variety of snow-producing storm systems. Preliminary results will be highlighted in the presentation, focusing on the variability in microphysical and multi-frequency radar characteristics within and outside of snowband structures. The role of supercooled liquid water, aggregation, and cloud top processes in contributing to regions of enhanced snowfall will be discussed.