At low latitudes in the tropics and subtropics the addition of wind fields to the observational data set should have a particularly strong impact. In this region the winds are a more important measure of the atmospheric state because the geostrophic relationship between the wind and mass fields is often invalid. Low latitudes are also the primary location for many important processes, including monsoons, tropical cyclones, tropical Atlantic and Indian Ocean circulations, and pole-ward transport of tropical/subtropical air to middle latitudes that could be better characterized with improved observations of tropospheric and stratospheric winds.
To provide the wind measurements needed to address these and other interesting scientific problems, the Winds from the International Space Station for Climate Research (WISSCR) mission is currently being studied. The primary WISSCR instrument is a hybrid Doppler lidar system mounted on the Japanese Experiment Module Exposed Facility of the International Space Station (ISS). Orbital inclination of the ISS is 52 degrees, which is well-suited to studies of tropical and subtropical phenomena. The WISSCR hybrid Doppler lidar design includes separate lidar subsystems optimized for aerosol and molecular scatter to provide tropospheric winds from the surface to the stratosphere. For WISSCR, full vector winds are obtained by alternating between orthogonal fore-and-aft scans directed to one side of the spacecraft track.
Because of its potential value to a number of countries, WISSCR is being developed as an international mission. Presently, an international science team is being formed to put together the mission science plan and to develop the assimilation capabilities for numerical analysis and forecasts using WISSCR observations. OSSE studies are also underway to assess impact of the mission and evaluate the positive and negative effects of cloudy regions.