System definition of the ESA Earth Explorer WALES mission

摘要

WALES (Water vapour Lidar Experiment in Space) is one of the three candidate missions that are currently considered for the future ESA Earth Explorer missions. The objective of the mission is to provide better insight into the distribution of water vapour and aerosol in the upper troposphere and lower stratosphere for research and applications in climatology and numerical weather prediction. This is to be achieved by providing globally accurate profiles of water vapour concentration. A direct detection Differential Absorption Lidar has been studied in the frame of the WALES mission pre-phase A. The lidar is based on high power laser emitting several wavelengths in the 920-950 nm range, each wavelength being tunable and frequency locked. The backscatter signal is collected through a large telescope and filtered through narrow band filters. The concept and the expected performance of the instrument are discussed in this paper.