HAO Colloquium - Federico Gasperini, HAO

A whole-atmospheric perspective on connections between intra-seasonal variations in the troposphere and thermosphere

In the last decade evidence demonstrated that terrestrial weather greatly impacts the dynamics and mean state of the thermosphere via small-scale gravity waves and global-scale solar tidal propagation and dissipation effects. While observations have shown significant intra-seasonal variability in the upper mesospheric mean winds, relatively little is known about this variability at satellite altitudes (~250-400 km). Using cross-track wind measurements from the Challenging Minisatellite Payload (CHAMP) and Gravity field and steady-state Ocean Circulation Explorer (GOCE) satellites, winds from a Modern-Era Retrospective Analysis for Research and Applications/Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model (MERRA/TIME-GCM) simulation, and Outgoing Longwave Radiation (OLR) data, I will demonstrate the existence of a prominent and global-scale 90 day oscillation in the thermospheric zonal mean winds and in the diurnal eastward propagating tide with zonal wave number 3 (DE3) during 2009-2010 and present evidence of its connection to variability in tropospheric convective activity. This study demonstrates that strong coupling between the troposphere and the thermosphere is occurring on intra-seasonal timescales, raising important questions including implications for the whole atmosphere system. 

Date and time: 
Wednesday, July 25, 2018 - 2:00pm to 3:00pm