Collaborative Research: AGS-FIRP Track 3: In-situ Collaborative Experiment for the Collection of Hail In the Plains (ICECHIP)

Hail is the most consistently damaging hazard of severe thunderstorms, producing losses in the U.S. alone exceeding $10 billion per year over the past 14 years with impacts on homeowners, business owners, aviation, agriculture, transportation, and renewable energy producers. The In-situ Collaborative Experiment for Collection of Hail In the Plains field campaign, or ICECHIP, will improve radar detection and monitoring of hail, provide critical ground-truth information for materials science, and improve the nation’s capabilities to predict hailstorms and their impacts. Current hail forecasting methods struggle to forecast more extreme hail events, and it is difficult to connect radar-observed storm characteristics with specific hail characteristics such as concentration or extreme sizes. Very few observations of hail characteristics other than maximum dimension are even available, nor knowledge of how those characteristics could change during a storm. ICECHIP, the first U.S. hail-focused field campaign in over 40 years, will use modern instrumentation and numerical modeling capacity to provide a long-awaited advancement in hail science. Mobile radars, unpiloted aerial systems, lofted drifters and probes, laser scanning technologies, high-resolution cameras, and more traditional field observations such as atmospheric conditions and surface hail size will all be used to obtain synchronized and comprehensive observations of hailstorms, the hailstones they produce, and the damage they cause. Researchers will deploy a fully mobile network for 6 weeks across the Front Range and Central Plains, gathering observations from a wide variety of hailstorms and hail types. This first-of-its-kind dataset will be instrumental in improving radar-based hail detection, hail models and forecasting, and resulting warnings through diverse collaboration among academic, government, private sector, and international partners. ICECHIP will promote educational efforts through training of 32 undergraduate and 20 graduate students across 10 U.S. universities, including two Minority Serving Institutions.ICECHIP will address 5 major research themes, each corresponding to a current significant gap in hail science. In Theme 1, which focuses on hailstone growth and fall behavior, advances in digital photography will be used to explore little-observed microscale hail processes such as tumbling, melting, and shedding with the aim of reducing the uncertainty in microphysical parameterizations and hail growth models. ICECHIP’s comprehensive observations will be used to validate newly developed hail trajectory models and parameterizations in Theme 2, which concentrates on in-storm hail trajectory and convective updraft relationships. Those models will then be used to explore how thunderstorm updraft characteristics and evolution can modify in-storm hail trajectories and surface hail production. Environmental impacts on hail processes and predictability will be examined in Theme 3 by quantifying model hail forecasting skill, with a particular focus on environmental wind, moisture, and temperature profiles. In Theme 4 the surface properties of hailstones and associated impacts will be investigated by linking the internal and environmental storm characteristics to predictable variations in observed hailstone properties (size, shape, density, and strength) in both space and time within the swath and through new insights derived into the impact of wind on hail impacts. These properties will be linked through laboratory and model experiments to different damage modes of materials and structures. Finally, in Theme 5, which focuses on relationships between hailstone physical properties and growth processes to radar observations, radar-based detection of hail size and concentration will be better established through comprehensive ground truth validation that includes the natural variability of hail properties. Radar indicators of updraft width will be linked directly to increases in hailstone mass and damage potential at the surface.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.