Thermospheric composition O/N2 response to an altered meridional mean circulation during Sudden Stratospheric Warmings observed by GOLD

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Wednesday, February 12, 2020

GOLD measurements provide the first observational proof of model predictions that the break up of the stratospheric polar vortex changes the composition of the thermosphere.

Graphic image of GOLD O/N2 ratios
(a) GOLD O/N2 ratios for 15 December 2018 (day 349, geomagnetic quiet, SZA< 80, 113W to 19E), averaged over all 30 minute cadence images taken during daytime. (b) Time series of O/N2 daytime means averaged over all observed longitudes as a function of geographic latitude (color contours), along with 10 hPa mean zonal winds in the stratosphere at 60N from MERRA-2 (black line). A SSW occurred around day 370 with onset on day 355. The lower panel shows the 3-hourly Kp index (black) and the F10.7 cm radio flux. © Same as (b) but with mean, annual and semi-annual components removed, using all available Level 2 data (6 Oct 2018 – 13 Aug 2019). Plotted as percent deviation.

The important O/N2 ratio is depleted by ~10% through a rather complex chain of processes that connect global-scale waves from the lower atmosphere, wave dissipation, mean meridional circulation, turbulent eddy transport, and molecular diffusion to produce a global O/N2 reduction in the thermosphere. The observed composition changes will likely impact Earth’s ionospheric plasma environment and imply a substantial impact of the lower and middle atmosphere on space weather.

Publication Name: Geophysical Research Letters
First HAO Author's Name: Nick Pedatella

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