A comparison between vertical winds in the lower thermosphere and magnetic field perturbations on the ground

Abstract

Vertical winds in the lower thermosphere are estimated from OI 557.7-nm Doppler shifts obtained with a Fabry-Perot interferometer at the Poker Flat Research Range (65.12 N, 147.43 W in geographic coordinate), Alaska. The temporal variation of vertical winds was compared with the horizontal component of the magnetic field obtained at Poker Flat and two other sites, Gakona (62.12 N, 145.14 W) and Fort Yukon (66.36 N, 145.22 W). Two nights of observations were examined and the results were shown here. The results showed that temporal variations of vertical winds were similar to that of magnetic field variation during each substorm. In some cases the results of cross correlation between these two parameters showed that the magnetic field perturbation leads vertical winds in the earlier period of the substorm. The difference increased gradually and reached a maximum at around the center of the recovery phase. From there, the differences decreased. The mechanism for the relation between the two parameters is still unclear, but this result suggests an intimate relation between ionospheric currents and vertical wind in the thermosphere.