The potential value of winds measured from space using Doppler lidar techniques has long been recognized. Observing system simulation experiments (OSSEs) have shown that assimilation of lidar-observed wind profiles from data sparse regions into numerical models can significantly improve medium range weather forecasts. Even when mass estimates, from which wind fields can be estimated through the geostropic relationship, are available, the addition of lidar-measured winds has a positive impact on prediction. Wind observations should also improve the quality of the reanalysis data sets widely used to investigate climate-related processes. As an example, significant differences currently exist between NCEP/NCAR and ECMWF reanalysis representations of the Hadley and Walker circulations, showing large discrepancies in the tropical divergent wind.

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.