Sampling Strategies to Optimize Coincident Remote Sensing and in Situ Cloud and Precipitation Observations from Multiple Aircraft

Collocated remote sensing and in situ microphysical and environmental data enable scientists to accurately interpret the remote sensing measurements with respect to microphysical processes and environmental conditions, advancing our understanding of cloud and precipitation processes. The Investigation of Microphysics and Precipitation in Atlantic Coast Threatening Snowstorms (IMPACTS) is a multi-year NASA field campaign that flew a complementary suite of remote-sensing and in-situ instruments on NASA aircraft in three 6-week deployments to provide observations critical to understanding the mechanisms of snowband formation, organization, and evolution. IMPACTS took place across three winter seasons (2020, 2022 and 2023) and used multiple assets to probe snowstorms. The high-altitude, satellite-simulating ER-2 was equipped with advanced radar, lidar, and microwave radiometer remote sensing instruments, and sampled cloud and precipitation structure from above the clouds. The in-situ NASA P-3 was equipped with microphysics probes, environmental instrumentation, and dropsonde capabilities, flying within the clouds of the storm at various altitudes from ~2 km to 8 km. Several previous field campaigns have collected coincident data in the past using 2 aircraft but obtaining collocated data to within 5 minutes is limited because coordinating 2 airplanes deploying from different airfields and that fly at different airspeeds is challenging. One recent successful example was the Olympic Mountain Experiment (OLYMPEX), which collected only 217 mins of collocated remote sensing and in situ data at temperatures less than 0°C over storms in the Pacific Northwest. By flying the two aircraft in a vertically stacked pattern with a 5-point flight leg, IMPACTS was able to collect over 21 hours of collocated remote sensing and in situ microphysics data (where the aircraft were within 5 mins of each other). This presentation describes the lessons learned in coordinating the 2 aircraft over 3 field deployments, the 5-point flight legs that enabled the collocation, statistics of collocation over the entirety of the project, and an example of enabled science.