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

Vertical winds in the lower thermosphere are estimated from OI557.7-nm Doppler shifts obtained with a Fabry-Perot interferometer at the Poker Flat Research Range (65.12N, 147.43W 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 (62.12N, 145.14W) and Fort Yukon (66.36N, 145.22W). 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

Development of an automatic observation system for Fabry-Perot interferometers

The importance of automatic observation systems for ground-based optical instruments is increasing since clustered measurements are being made with only a few operators. We have developed an automatic observation system for use with both a scanning and an all-sky Fabry-Perot interferometer. This paper describes the optical system of the instrument, its performance when observing auroras, and the details of the automatic observation system. The S/N ratio of the observed fringe exceeds 500, even if the auroral activity is low. Using the Internet or telephone lines, an operator can monitor and control multiple optical instruments from a remote site. In addition, we introduce a new analysis software for estimating the emission intensity, wind velocity and temperature. Once the system is further improved by modifying it to enable radio communication, the construction of remote-controlled, relocatable observatories will become feasible, representing a remarkable evolution in optical measurement technology

Development of Fabry-Perot interferometers for airglow observations

We are developing an all-sky and a scanning Fabry-Perot interferometer for studying the dynamics of the thermosphere and the mesosphere in the polar region. Our instruments have three unique features useful for airglow observation; (1) Each instrument can obtain interference fringes at two different wavelengths at a time using a dichroic mirror, (2) The instruments can observe very weak airglow with the aid of a photon counting imager, (3) When operated simultaneously, the all-sky and the scanning Fabry-Perot interferometer can observe vertical winds in addition to two-dimensional atmospheric motions. We have made two test observations at the Zao observatory, Tohoku University in 1994,and at the Shigaraki observatory, Kyoto University in 1995