ALADIN airborne demonstrator: a Doppler Wind lidar to prepare ESA's ADM-Aeolus Explorer mission

摘要

The Atmospheric Dynamics/Aeolus mission is the 4th Earth Explorer mission of the Earth Observation Explorer Programme of the European Space Agency (ESA). Its objective is to measure vertical tropospheric profiles of horizontal wind speed components. These global observations of wind profiles from space will improve the quality of weather forecasts and advance our understanding of atmospheric dynamics and climate processes. The 1.3-ton, 1.4-kW Aeolus spacecraft uses an incoherent Doppler Wind lidar (ALADIN) to measure wind speed. It uses a tripled-frequency Nd:YAG laser emitting ultraviolet pulses at a repetition rate of 100 Hz, during a measurement period of 7 sec repeated every 28 sec. The return signal is detected with a double interferometric receiver composed of a Fizeau interferometer to detect the Mie signal scattered by aerosols and a double-edge Fabry-Perot interferometer to detect the Rayleigh signal scattered by atmospheric molecules. A custom-made accumulation CCD is used to detect and integrate the return photons over several laser pulses. The spacecraft has recently passed the CDR level and launch is planned for 2008. An airborne version of the ALADIN instrument has been made with equipment developed during the pre-development phase of the mission. An interferometric receiver with a high-level of representativity to the space receiver and a laser transmitter breadboard have been refurbished and complemented with a telescope, a co-alignment mechanism and custom control and processing electronics to produce the first airborne, direct-detection Doppler Wind lidar worldwide. The lidar was functionally tested in flight in October 2005 and will be used in ground and airborne campaigns in 2006 and 2007 to prepare the exploitation of the Aeolus space mission.