Abstract
In order to validate wind vectors derived from NSCAT,statistical distributions of wind speeds
and directions over the global oceans are investigated by comparing with ECMWF wind data.
Histograms of wind speeds and directions are calculated from the Preliminary NSCAT Science
Data Products for a period of about one month. For the wind speed, excessive low wind distribution
is pointed out by the comparison of histograms with ECMWF winds. A hump at the lower wind
speed side of the peak in the histogram of wind speeds is discernible. Shape of the hump varies
with the incidence angle. Incompleteness of the pre-launch geophysical model function, SASS-2,
tentatively used to retrieve wind vectors from backscatter measurements, is considered to cause the
skew of the wind speed distribution. Frequency distribution of the wind directions relative to the
spacecraft flight direction is calculated to assess selfconsistency of the wind directions. It is found
that the NSCAT-derived wind vectors may exhibit systematic directional preference relative to the
antenna beams in comparison with those of the ECMWF winds. This artificial directivity is also
considered to be caused by imperfections in the model function. Dependencies of the directional
distributions on incidence angle and wind speed are also discussed.
