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

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

Research output: Contribution to journalArticleScientificpeer-review

18 Citations (Scopus)
22 Downloads (Pure)

Abstract

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.

Original languageEnglish
Pages (from-to)739-754
Number of pages16
JournalJournal Of Geophysical Research-Space Physics
Volume123
Issue number1
DOIs
Publication statusPublished - 1 Jan 2018

Keywords

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

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