[세미나] Dr. Nicholas Pedatella

Predictability of the Mesosphere and Lower Thermosphere during Major Sudden Stratospheric Warmings

#### Dr. Nicholas Pedatella (National Center for Atmospheric Research) #### 2021년 9월 17일 (금) 11:00 #### Zoom
#### Abstract Sudden stratospheric warmings (SSWs) significantly influence the entirety of Earth’s atmosphere, with effects ranging from the troposphere to the ionosphere and thermosphere. The impacts of SSWs on the upper atmosphere are especially dramatic, and SSWs are recognized as a significant source of the day-to-day weather of the near-Earth space environment. As SSWs can be predicted ~10-15 days in advance, they provide the potential to improve predictability of the near-Earth space environment. In this study, the predictability of the middle atmosphere during major SSWs is investigated based on subseasonal hindcasts in the Community Earth System Model, version 2 with the Whole Atmosphere Community Climate Model as its atmospheric component (CESM2(WACCM6)). The CESM2(WACCM6) hindcasts allow for the first comprehensive investigation into the predictability of the mesosphere and lower thermosphere (MLT) during SSWs. Analysis of 14 major SSWs demonstrates that CESM2(WACCM6) hindcasts initialized ∼5-15 days prior to the SSW onset are able to predict the timing of the SSW, though they underestimate the strength of the SSW. Aspects of the MLT variability, such as the mesosphere cooling and enhanced semidiurnal tide, are found to be well predicted. The demonstrated ability to predict MLT variability during SSWs indicates the potential for improved multi-day space weather forecasting through the use of whole atmosphere models that can predict the MLT variability that drives ionosphere-thermosphere variability during SSWs.