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Several processes related to off-shore
activities require the knowledge of accurate surface winds and
sea states on fine high space and time resolution. The former
are both critical for determining the dynamical forcing of
the ocean, the estimation of ocean surface currents, waves and
related boundary layer processes, and the dispersion and drift
of oil and other . Surface wind vectors might be estimated
from radars and radiometers onboard satellites, and are
routinely calculated by NWP centers. One the main aim of Work
Package 4 of Mersea project is to enhance the quality and the
spatial and temporal resolutions of surface parameters based
on the use of remotely sensed observations and numerical
analyses (ECMWF) at global scales. Ocean surface wind
observations are retrieved from QuikSCAT scatterometer and
from SSM/I radiometers available at near real time at
Météo-France. Using synchronous satellite data, the number of
remotely sensed data available for each analysis epoch
(00:00h; 06:00h; 12:00h; 18:00h) is not uniformly distributed
as a function of space and time. On average two-satellite wind
observations are available for each analysis time period. The
analysis is performed by optimum interpolation (OI) based on
the kriging approach. The needed covariance matrixes are
estimated from the satellite wind speed, zonal and meridional
component observations. The quality of the 6-hourly resulting
blended wind fields on 0.25° grid are investigated trough
comparisons with the remotely sensed observations as well as
with moored buoy wind averaged wind estimates. The blended
wind data and remotely wind observations, occurring within 3
hours and 0.25° from the analysis estimates, compare well over
the global basin as well as over the sub-basins. The
correlation coefficients exceed 0.95 while the rms difference
values are less than 0.30m/s. Using measurements from moored
buoys, the high-resolution wind fields are found to have
similar accuracy as satellite wind retrievals. Blended wind
estimates exhibit better comparisons with buoy moored in open
sea than near shore.
Blended Mean Wind Field, 6 hourly, near real time Web Site
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