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