CEDAR: Downward Progression of Temperature Anomalies during Sudden Stratospheric Warmings

University Of California-Berkeley, Berkeley CA

Investigators

Abstract

The polar atmosphere often exhibits unexpected and significant temperature anomalies called Sudden Stratospheric Warmings (SSWs) that show a downward progression. The progression of anomalies can start in the mesosphere and lower thermosphere region near 80 km in altitude and go all the way down to tropospheric heights of around 30 km. Because of their downward progression, SSWs represent an important process for downward coupling between atmospheric regions. They are believed to be a product of interaction between planetary waves and the mean atmospheric flow (winds), but it has also been suggested that atmospheric disturbances originating from lower altitudes (gravity waves) play an important role in this interaction by creating the right set of conditions for downward progression (pre-conditioning). The research work will exploit the recently obtained results of data assimilation runs in combination with a number of atmospheric models. The downward coupling processes in the upper and middle atmosphere are important because of their potential impact on the stratospheric ozone and other important constituents. The work will involve (1) analysis of characteristics of the temperature anomalies and atmospheric waves using data from satellite measurements and global atmospheric model results, (2) numerical simulations of wave propagation and comparison of the results with characteristics of the temperature anomalies, and (3) investigation of whether pre-conditioning occurs through a change in the zero-wind line height by running ensemble simulations. This work will improve the understanding of the role that atmospheric waves play in downward coupling in the polar upper atmosphere and can potentially improve the ability to model climate and space weather disturbances. 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.