Contributors: Wenqing Tang and W. Timothy Liu

Objectively-interpolated and uniformly gridded wind field can be downloaded online at http://airsea.jpl.nasa.gov/data for observations by QuikSCAT, ERS and NSCAT. Regional wind and stress field will be produced with temporal and spatial resolutions tailored to our specific research needs.

QuikSCAT measures surface wind speed and direction, covering 93% of the global ocean under clear and cloudy conditions, night and day. The standard 25-km resolution wind product of QuikSCAT is derived from an ellipsoidal instantaneous antenna footprint with characteristic dimension of 25 x 35 km (so-called 'egg'). Using onboard filtering, the egg can be divided into smaller, contiguous 'slices' having characteristic dimensions of about 6 x 25 km. The computation of backscatter and wind from the slices will, in principle, provide higher spatial resolution. A review of scatterometer capabilities and applications is given by Liu [2002]. A limited amount of surface wind data at 12.5 km resolution has been produced from QuikSCAT and successfully applied in studies of tropical cyclones and coastal eddies [Liu et al., 2001].

The scatterometer project has no plan and has devoted no resource to produce high resolution wind from slice data as standard data product, and slice data are not openly accessible. The accuracy of the present scatterometer winds may be degraded within 25 km of the land because of land contamination. W. Timothy Liu (QuikSCAT Project Scientist) and Wu-yang Tsai (QuikSCAT Project Engineer) are studying the trade-off between higher spatial resolution and more accuracy degradation, in using slice data to produce coastal wind products. W. Timothy Liu and his collaborators plan to produce of an experimental coastal wind product by combining the scatterometer slice product with measurements for synthetic aperture radar to bring the winds closer to the coast, and by merging observations of sensors flying in tandem to increase the temporal resolution.

References:
Liu, W.T., H. Hu, Y.T. Song, and W. Tang, 2001: Improvement of scatterometer wind vectors - impact on hurricane and coastal studies. Proc. WCRP/SCOR Workshop on Intercomparison and Validation of Ocean-Atmosphere Flux Fields. WCRP-115,World Climate Research Programme, Geneva, ,197-200.

Liu, W.T., 2002: Progress in scatterometer application, J. Oceanogr., 58, 121-136.

Tang, W., W.T. Liu, and B.W. Stiles, 2004: Evaluation of high-resolution ocean surface vector winds measured by QuikSCAT scatterometer in coastal region. IEEE Trans. Geoscience and Remote Sens. in press.