AGS-PRF: Establishing Causality in the Angular Momentum Budget of the Atmosphere: Insights from the Quasi-Biennial Oscillation

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This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).The Quasi-Biennial Oscillation (QBO) describes the alternating direction of the longitudinally averaged equatorial wind in the middle-to-lower stratosphere at roughly every 27 months. Over time, this alternating pattern descends toward the tropopause before diminishing at the altitude range of 13-19 km. In this range, the QBO can influence the tropospheric jet stream and tropical convection, thereby affecting the global weather and climate. The diminished QBO wind can be attributed to the atmospheric torque associated with the dissipation of atmospheric waves propagating upward into the tropopause region. To date, the impact of the atmospheric torque on the QBO and, eventually, on the tropospheric circulation is not well understood. Current climate models cannot properly simulate the observed descent of the QBO eastward wind across the tropopause, and this failure may be due to the improper torque representation in models.This work aims to advance our understanding of atmospheric torque and the global influence of the QBO. Mentored by a well-established sponsor, the investigator will use observations and numerical models of varying complexity to address this goal. The research tasks will focus on testing theories on the torque-QBO relationship in observations and models, assessing the influence of the QBO on the mid-latitude jet, and quantifying the influence of torques on tropical convection. These efforts could help advance future modeling capabilities by improving climate projections and subseasonal-to-seasonal forecasts of regional precipitation and mid-latitude jet dynamics. The investigator will also make public-engagement presentations to provide insight into climate change related to the research work.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.