The NASA EOS generation of polar-orbiting meteorological satellites is designed to showcase promising new technologies that will serve as candidates for future operational sensors. The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument aboard the Terra and Aqua satellites provides measurements in many spectral bands not found on previous polar-orbiting imagers, including a high-resolution water vapor channel. Algorithms developed at UW-CIMSS to derive winds from the motion of clouds and water vapor features with geostationary satellites have been successfully adapted for use with MODIS data. In the polar regions, overlapping successive orbits at 100-minute intervals provide traceable cloud and water vapor targets.

Given the sparsity of upper-air meteorological observations, this new data has the potential to significantly impact polar analyses and numerical weather prediction. Experiments with a one-month case study data set have shown a positive impact on numerical model forecasts for the Arctic, Antarctic, and extratropics. These results prompted an effort to begin a routine, near real-time generation of MODIS winds. We will report on the status of this demonstration phase in terms of improvements to the winds processing algorithm, timeliness of the data product, and the impact these data have when assimilated routinely into several different numerical models.

We continue to address the challenges associated with deriving winds from polar-orbiting satellites over the remote regions of the Arctic and Antarctic. These include temporal sampling issues, feature displacement due to parallax in successive orbits, and uncertainties in wind height assignment due to the complexity of surface features, temperature inversions, low atmospheric water vapor amounts, and thin clouds typical of the polar regions.