Differentiating Cyclogenesis with and without Large Amplitude Mesoscale Gravity Waves: Implications for Rapidly Varying Heavy Precipitation and Gusty Winds

Atmospheric gravity waves refer to air that rises and sinks due to an initial displacement and then propagates outward, like a ripple on a pond. While atmospheric gravity waves are commonly generated by mountainous terrain or hurricanes and thunderstorms, they can also form within developing low pressure systems, such as large snowstorms. The enhanced rising motion from the gravity waves can contribute to more intense precipitation and wind, making them extremely relevant to society. However, not all developing systems contain gravity waves. This research project will investigate the causes of gravity waves in developing cyclones using numerical modeling and observations of storms with and without gravity waves. The potential outcome of this work is an improved ability to forecast gravity waves and the resultant high-impact weather that they produce. The project will include two graduate students, thereby training the next generation of scientists. This project will assess rapidly developing mid-latitude cyclones and their relationship to gravity wave production. The research team theorizes that predicting gravity waves during cyclogenesis and cyclone evolution requires a multi-scale theory to separate the dynamical evolution from their precursor environments. The evolution of cyclone formation will be inter-compared with gravity wave genesis, amplification, and maintenance with the goal to create a theory that reliably separates gravity wave-coupled cyclone cases from non-gravity wave cyclones. The specific hypothesis that will be tested is that for cyclogenesis with large amplitude gravity waves, the phasing of the mid-upper tropospheric isentropic potential vorticity is more focused among the unbalanced jet exit region flow with wide separation between the geostrophic and total wind maxima, mid-upper tropospheric warm front, and diabatic heating. To address this hypothesis, a case study-based numerical modeling approach would be undertaken, using the WRF-ARW model in a 1km nested configuration. The modeling work will consist of full-physics simulations, with validation against observations and additional simulations to assess the impacts of different physics schemes and initial conditions. 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.