IMPACTS

Winter snowstorms are frequent on the eastern seaboard and cause major disruptions to transportation, commerce, and public safety. Snowfall within these storms is frequently organized in banded structures that are poorly understood by scientists and poorly predicted by current numerical models. The capabilities of remote sensing technologies and numerical weather prediction models have advanced significantly, making IMPACTS a well-equipped study to identify key processes and improve remote sensing and forecasting of snowfall.

The Investigation of Microphysics and Precipitation for Atlantic Coast-Threatening Snowstorms (IMPACTS) flew a complementary suite of remote sensing and in-situ instruments for three 6-week deployments on the ER-2 and P-3 aircraft. IMPACTS addressed three specific objectives, providing observations critical to understanding the mechanisms of snowband formation, organization, and evolution. IMPACTS also examined how the microphysical characteristics and likely growth mechanisms of snow particles vary across snowbands. IMPACTS improved snowfall remote sensing interpretation and modeling to significantly advance predictive capabilities.

INSTRUMENTS AND AIRCRAFT

The IMPACTS airborne instrument suite provided a synergistic range of measurements for snow process studies. It combined advanced radar, lidar, and microwave radiometer remote sensing instruments on the ER-2 with state-of-the-art microphysics probes and dropsonde capabilities on the P-3 to sample US East Coast winter storms. By flying the two aircraft in an approximately vertically stacked coordinated pattern, with flight legs generally orthogonal to the snowband orientation, the instrument suite provided approximately collocated dynamical and microphysical measurements that will advance our understanding of processes in winter storms.

IMPACTS collected data from a “satellite-simulating” ER-2 and in-situ measurements from a cloudpenetrating P-3, augmented by ground-based radar and rawinsonde data, multiple NASA and NOAA satellites [including GPM, GOES-16, and the Joint Polar Satellite System (JPSS)], and computer simulations. The ER-2 and P-3 provided the flight-altitude and long-endurance capabilities and payload capacity needed for the combined remote sensing and in-situ measurements.