New 2018 HIWIND Thermospheric Wind Observations

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Thursday, June 13, 2019

Daytime thermospheric winds observed by the balloon-borne instrument HIWIND (High altitude Interferometer WIND experiment) during two flights in June 2011 and 2018 from Kiruna (68°N, 20°E), along with simultaneous EISCAT (European Incoherent SCATter radar) ion drift data, are analyzed.

Graphs depicting 2018 HIWIND Thermospheric Wind Observations
Observations and simulations for the first day of the 2018 (left) and 2011 (right) flights. The meridional (upper) and zonal (lower) components of thermospheric winds from HIWIND (pink dots), ion drifts from EISCAT (green), and TIEGCM simulated winds (dark blue). The ion drift scale is on the right in m/s, which is double the scale for the neutral winds. The wind errors for HIWIND observations ranges from 15 to 30 m/s.

NCAR TIEGCM (Thermosphere Ionosphere Electrodynamics General Circulation Model) simulations for both flights are compared with observations. The observed thermospheric winds from the two flights have many similarities. HIWIND observed thermospheric winds tend to be equatorward during the morning hours before noon and close to zero in the afternoon. In contrast, TIEGCM predicts poleward winds before noon and near zero in the afternoon. Southward IMF Bz, occurring as the balloon passed through morning, was associated with greater equatorward meridional winds. The TIEGCM simulated zonal winds have large differences with observations under more active conditions. The second HIWIND flight confirms some important results from the first flight and further shows thermospheric wind variations under different IMF conditions. HIWIND observations in general provide invaluable data for model validation and highlight deficiencies in current high latitude simulations.

Publication Name: JGR Space Physics
First HAO Author's Name: Qian Wu