The doppler wind and temperature system of the ALOMAR lidar facility: overview and initial results

Abstract

The Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR) facility is a new and major facility for atmospheric research. It is located at Andøya in Northern Norway. One of the important facilities of ALOMAR is the Doppler Wind and Temperature System (DWTS). The DWTS will determine atmospheric wind and temperature profiles between about 8 and 90 km altitude from the Doppler shift and broadening of the lidar signal Rayleigh back-scattered from the atmosphere. The DWTS uses a double-etalon Fabry-Perot interferometer to perform the high-resolution spectral analysis of the back-scattered lidar signal, and to reject the bright background light from the daytime sky. After spectral analysis, the Fabry-Perot fringes are imaged onto a multi-ring anode imaging photon detector which provides, pulse-by-pulse, time-resolved detection of the spectrum of the laser light back-scattered from the atmosphere. The double-etalon Fabry-Perot interferometer has been designed to detect the returned signal during daytime, and thus summer-time conditions at ALOMAR, as well as during night-time. The entire optical system has been designed to maximise the transmission and detection of light, to make maximum use of the faint signals available from high-altitude regions, up to around 80–90 km. This paper reports on the objectives and design of the ALOMAR DWTS, and presents some initial results obtained during commissioning periods in October 1994 and January 1995.