Open AccessOn the sub‐grid‐scale variability of oceanic winds and the accuracy of numerical weather prediction models as deduced from QuikSCAT backscatter distributions
Author(s) -
Suzuki Naoya,
Donelan Mark A.,
Plant William J.
Publication year - 2007
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2005jc003437
Subject(s) - scatterometer , wind speed , mesoscale meteorology , meteorology , environmental science , numerical weather prediction , latitude , climatology , geology , geodesy , physics
Observed probability distributions of QuikSCAT scatterometer cross sections are matched to expected distributions calculated using a Geophysical Model Function (GMF) with a wind speed threshold and inherent wind variability on the subfootprint scale and also on grid scales of numerical weather prediction (NWP) models. Two independent approaches are taken: In one, the 3‐D sample size is 2° × 2° and 1 day, and the wind speed is assumed to be Rayleigh distributed while directions relative to QuickSCAT antenna directions are assumed to be uniform; in the other, the data are binned by NWP analyzed wind speeds into 1 m/s bins and sample sizes of the grid area of the NWP models. Using the results, the variability on these scales is mapped as a function of wind speed, latitude, and season in an effort to establish a global climatology of wind‐speed variability. On the basis of the stable calibration of QuikSCAT, the bias of surface winds produced by the National Center for Environmental Prediction (NCEP) and the European Center for Medium‐Range Weather Forecasts (ECMWF) is shown to be substantial and strongly dependent on wind speed, latitude, and season. Changes in wind‐speed variability with changes in averaging scale are further explored and estimates of the kinetic energy spectra of the mesoscale to basin‐scale winds are determined.