Analysis and Hindcast Experiments of the 2009 Sudden Stratospheric Warming in WACCMX+DART

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Thursday, December 7, 2017

Plain Language Summary or Abstract: Whole atmosphere models offer the opportunity to improve specification and forecasting of the upper atmosphere through incorporating the effects of forcing from both the lower atmosphere as well as the Sun.

Total electron content (TEC) image
Total electron content (TEC) at 75W geographic longitude and 1800 local time for (a) SD-WACCMX, (b) WACCMX+DART, and (c) GNSS TEC observations

This study presents initial results from a data assimilation version of the Whole Atmosphere Community Climate Model extended version (WACCMX+DART). WACCMX extends from the surface to ~500 km altitude, and thus simultaneously models the lower, middle, and upper atmospheres. By assimilating meteorological observations in the troposphere-stratosphere, and satellite observations in the mesosphere, WACCMX+DART reanalysis fields are shown to reproduce the ionosphere variability during the 2009 sudden stratospheric warming (SSW) event. The ionosphere predictability during the 2009 SSW event is also assessed through a series of hindcast experiments that are initialized approximately 20, 15, 10, 5, and 0 days prior to the central (i.e., peak) date of the SSW. The hindcast experiments reveal that, for the 2009 SSW event, the middle and upper atmosphere variability can be qualitatively forecast 10-20 days in advance. The results demonstrate that it is possible to extend the useful forecast range of the ionosphere-thermosphere through incorporating lower atmosphere effects, at least during periods of quiescent solar activity.