MF (medium frequency) radars (MFR) are powerful tools for understanding the upper atmosphere, by measuring horizontal wind velocity and electron density. This article introduces three MFR systems, two in Japan, Yamagawa (31.20N, 130.62E) and Wakkanai (45.36N, 141.81E) radars, and one at Poker Flat, Alaska (65.1N, 147.5W). Experimental techniques, and their observed results are briefly shown. Horizontal wind velocity was observed by those MFRs, in height ranges of 60-100 km (day) and 80-100 km (night) at Yamagawa and Wakkanai, while the data coverage is unusually low, >54 km (day) and >68 km (night), at Poker Flat. Comparison of MFR winds with temperature observed by a collocated Rayleigh lidar at Poker Flat shows consistency of those two instrument results in terms of atmospheric wave theory, implying validity of MFR data at such low altitudes. Electron density results at Poker Flat agree reasonably with International Reference Ionosphere model values at 74-84 km, and agree well with variation of cosmic noise absorption by the Poker Flat imaging riometer, suggesting valid electron density estimation by MFR at least below 80-85 km.

A Rayleigh lidar (laser radar) system was developed and is now working well for temperature observations of the middle atmosphere at Poker Flat Research Range near Fairbanks, Alaska (65.1 N, 147.5 W). A comparison of lidar data and balloon sonde data showed good agreement in overlapped altitudes. The atmospheric fluctuations are detected in the temperature profiles obtained by the Rayleigh lidar and these are useful for the study of gravity waves. A Rayleigh Doppler lidar for wind measurements of the middle atmosphere is under the phase of development. The expected accuracy in measurements of horizontal winds up to an altitude of 60 km is smaller than 6 m/s in 2 hours observation. The system will be operated at Poker Flat after the completion of development. The combination of these lidars and radars installed at Poker Flat, give us chances of simultaneous observations of the structure and dynamics of the atmosphere in broad range of altitudes. Here, we give descriptions of the Rayleigh lidar and the Rayleigh Doppler lidar for the observations of the Arctic middle atmosphere at Poker Flat.