Neutral wind spectra at the auroral zone mesopause: Geomagnetic effect?

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Abstract
Measurements of auroral zone neutral winds at the mesospause obtained by the MST radar at Poker Flat, Alaska (65°N), in June and July of 1980–1982 have been spectrally analyzed for evidence of an effect of enhanced electrojet activity upon the wind spectrum. The horizontal component of the College magnetometer was used to indicate the level of geomagnetic activity. The high‐frequency portion of the gravity wave regime (periods shorter than about 6 hours) appears quite constant with no apparent correlation with local electrojet activity. The average intensity of lower‐frequency waves is quite variable from year to year. On a yearly basis, the data suggest alterations in the intensity of some low‐frequency waves in conjunction with enhanced geomagnetic activity. However, zonal and meridional wind fluctuations did not vary with the level of geomagnetic activity in a consistent manner for all 3 years of data studied at any specific frequency. This may indicate a dependence of any relationship between the intensity of low‐frequency neutral wind oscillations at the mesopause and geomagnetic activity on the average background state of the neutral wind spectrum for that period.