The Global Characteristics of the Wavenumber Spectrum of Ocean Surface Wind

The wavenumber spectra of wind kinetic energy over the ocean from Quick Scatterometer (QuikSCAT) observations have revealed complex spatial variability in the wavelength range of 1000-3000 km, with spectral slopes varying from -1.6 to -2.9. Here the authors performed a spectral analysis of QuikSCAT winds over the global ocean and found that (i) the spectral slopes become steeper toward the Poles in the Pacific and in the South Atlantic, and the slopes exhibit minimal longitudinal dependence in the South Pacific; (ii) the steepest slopes are in the tropical Indian Ocean and the shallowest slopes are in the tropical Pacific and Atlantic; and (iii) the spectra are steeper in winter than summer in most regions of the midlatitude Northern Hemisphere. The new findings reported in the paper provide a test bed for theoretical studies and atmospheric general circulation models.