Seasonal Dependence of Geomagnetic Active-Time Northern High-Latitude Upper Thermospheric Winds

Seasonal Dependence of Geomagnetic Active-Time Northern High-Latitude Upper Thermospheric Winds

Dhadly, Manbharat S. (Naval Research Laboratory)
Emmert, John T. (Naval Research Laboratory)
Drob, Douglas P. (Naval Research Laboratory)
Conde, Mark G. (University of Alaska Fairbanks)
Doornbos, E.N. (TU Delft Astrodynamics & Space Missions)
Shepherd, Gordon (York University)
Makela, Jonathan (University of Illinois at Urbana Champaign)
Wu, Qian (University Corporation for Atmospheric Research)
Nieciejewski, Richard J. (University of Michigan)
Ridley, Aaron J. (University of Michigan)

2018-01-01

This study is focused on improving the poorly understood seasonal dependence of northern high-latitude F region thermospheric winds under active geomagnetic conditions. The gaps in our understanding of the dynamic high-latitude thermosphere are largely due to the sparseness of thermospheric wind measurements. With current observational facilities, it is infeasible to construct a synoptic picture of thermospheric winds, but enough data with wide spatial and temporal coverage have accumulated to construct a meaningful statistical analysis. We use long-term data from eight ground-based and two space-based instruments to derive climatological wind patterns as a function of magnetic local time, magnetic latitude, and season. These diverse data sets possess different geometries and different spatial and solar activity coverage. The major challenge is to combine these disparate data sets into a coherent picture while overcoming the sampling limitations and biases among them. In our previous study (focused on quiet time winds), we found bias in the Gravity Field and Steady State Ocean Circulation Explorer (GOCE) cross-track winds. Here we empirically quantify the GOCE bias and use it as a correction profile for removing apparent bias before empirical wind formulation. The assimilated wind patterns exhibit all major characteristics of high-latitude neutral circulation. The latitudinal extent of duskside circulation expands almost 10^∘ from winter to summer. The dawnside circulation subsides from winter to summer. Disturbance winds derived from geomagnetic active and quiet winds show strong seasonal and latitudinal variability. Comparisons between wind patterns derived here and Disturbance Wind Model (DWM07) (which have no seasonal dependence) suggest that DWM07 is skewed toward summertime conditions.

data assimilation
F region neutral winds
geomagnetic active-time thermospheric winds
high-latitude thermosphere
ion-neutral coupling
seasonal climatology

http://resolver.tudelft.nl/uuid:0c4989de-01cc-41a5-ab90-07d85f1890ce

https://doi.org/10.1002/2017JA024715

2018-07-31

2169-9380

Journal Of Geophysical Research-Space Physics, 123 (1), 739-754

Institutional Repository

journal article

© 2018 Manbharat S. Dhadly, John T. Emmert, Douglas P. Drob, Mark G. Conde, E.N. Doornbos, Gordon Shepherd, Jonathan Makela, Qian Wu, Richard J. Nieciejewski, Aaron J. Ridley