Collaborative Research: Mesoscale Airmasses with High Theta-E (MAHTE)

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).

Severe thunderstorms are commonly associated with hot and humid airmasses. However, there is evidence that storms can be maintained or even enhanced on the cooler side of a boundary in certain circumstances. This research project will analyze these scenarios, where the cool side of an airmass has significant energy available to fuel thunderstorms. The researchers will develop a climatology of cases and analyze the physical processes responsible for their development. The research has direct impact on public safety through improved forecasting of severe weather events. Multiple students would be involved in the project, ensuring training of the next generation of scientists.

The research team will conduct a study of mesoscale airmasses with high theta-e (MAHTE), which are generally areas of moist air with high Convective Available Potential Energy (CAPE) values on the cool side of a frontal or outflow boundary. This award is for a foundational study on MAHTEs to determine their climatology and the physical processes responsible for their development. Analysis of surface observations will provide the spatial distribution, diurnal cycle, and seasonality of MAHTEs within the US. Idealized simulations would be used to provide a thorough understanding of the processes through which MAHTE develop. The following hypotheses will be tested: 1) The primary mechanism through which MAHTE develop is differential vertical advection across the airmass boundary, 2) A secondary mechanism through which MAHTEs develop is locally-enhanced surface fluxes of moisture near the leading edge of the MAHTEs, and 3) MAHTE formation is likely to depend on the environmental wind shear.

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.