Analysis of the neutral wind profiles from the HEX II experiment.

摘要

The HEX II sounding rocket experiment was carried out on February 14, 2007, during active geomagnetic conditions. Three rockets released trimethyl aluminum (TMA) chemical tracer trails to measure the neutral winds. Three neutral wind profiles obtained from the upleg trails are presented. The profiles are characterized by a strong wind peak around 113 km altitude in the northwestward direction. Below the peak, the winds exhibit strong shear and a smaller wind peak at around 103 km in the southeastward direction. The wind magnitudes are too strong to be attributed to tidal forcing. Above 120 km the winds are consistently to the northwest as a result of ion drag from the plasma convection pattern. The HEX II experiment results are compared to other high latitude neutral wind measurements. The wind peaks are comparable in magnitude to other wind measurements during similar geomagnetic conditions. A comparison of the neutral winds indicates a correlation of wind magnitudes with geomagnetic activity. A calculation of Hall and Pedersen drag coefficients indicates that the strong wind peak can be explained by modified geostrophy. Two possible explanations for the lower wind peaks are presented, primarily the possibility that meteoric dust affects the neutral winds.