Characterized by an abrupt break-down of the Northern Hemisphere winter polar vortex, a major stratospheric sudden warming (SSW) can elicit notable and unexpected changes in the mesosphere, as underlined by recent evidence of an elevated stratopause at 80 km. The connection between the stratosphere and mesosphere is potentially tied to gravity waves (GWs) and planetary waves (PWs), dynamical features on the opposite ends of the spatiotemporal spectrum.
Given this background, this project seeks to illuminate the stratosphere-mesosphere coupling with respect to major SSWs by (1) characterizing the sources/properties of GWs and PWs in the stratosphere and mesosphere, and by (2) assessing their roles and interactions in driving this coupling and the elevated stratopause. It will employ a three pronged, multiple-scaled approach, based on the National Center for Atmospheric Research (NCAR) Whole Atmosphere Community Climate Model (WACCM), the University of Oklahoma's Advanced Regional Prediction System (ARPS), and observations. Using WACCM, resolved planetary-scale and parameterized GW forcings will be examined along with the wave-induced circulation that enhances tracer transport into the stratosphere and influences surface climate. With high spatial resolution, the ARPS simulations will explicitly resolve much of the GW activities up to the lower mesosphere. Through ARPS, the elucidated GW properties will help clarify their sources and forcings seen in WACCM. Finally, satellite observations and analysis products (with inferred and parameterized GW influence) will be examined and compared to model results.
The broader impacts of this work are multifold. In the past decade, examinations of major SSWs have focused predominantly on their potential impacts on the troposphere. By broadening the current views to include the mesosphere and details of GWs, new insights on SSW evolution can be obtained through this project. Additionally, related project activities aim to enrich undergraduate education inside and outside the classroom. Participating undergraduates will conduct experiments, analyze model and observational data, and present research results. Finally, the project offers undergraduate research training and exposure to cutting-edge geophysical research that (1) may not otherwise be available at similar state-supported Liberal Arts institutions and that (2) is unique in South Carolina and the greater Southeastern Region.
