Advances in Stereo Winds
Over the last several years, NASA-NOAA collaborations have been developing stereo methods to observe winds enabled by the excellent geometric accuracy of modern operational satellite products. This allows for the direct geometric determination of the wind height in the atmospheric column with the expectation that geometric height assignments are more reliable and accurate than those inferred from IR brightness temperatures and modeled thermodynamics. The stereo method has been applied to pairs of Geostationary (GEO) satellites and a GEO paired with a Low Earth Orbiting (LEO) sensor such as MISR or MODIS. The GEO-GEO capability is being developed as a pre-operational product at NOAA using the GOES-R and Himawari series satellites. Recently, the portfolio of stereo-winds capabilities has been expanded to include GEO-VIIRS and Multi-LEO combinations of MODIS, VIIRS, and Sentinel-3 SLSTR. The GEO-VIIRS capability includes both single and tandem VIIRS cases and together with the GEO-GEO case are planned to constitute a future operational Enterprise stereo-winds capability for NOAA.
The Multi-LEO case brings stereo methods to the poles. The MODIS-SLSTR combination is of particular interest. The nadir and oblique views of the Earth from SLSTR and full-orbit overlap with Terra/MODIS allows for stereo coverage of the equatorial, mid-latitude, and polar regions in both IR and VIS. The polar IR case enables winter/summer observations of the polar circulation and provides a useful solution to the challenge of discriminating clouds from snow/ice. Polar crossings with CALIPSO once per orbit are guaranteed and provide a means to validate retrieved wind heights.
In this paper, we report on these new developments with validations against rawinsondes, retrieved ground points, Aeolus, and forecast wind fields.
