GEOPHYSICAL TURBULENT CHARACTERISTICS INFERRED FROM OBSERVATIONS OF SUBMESOSCALE SURFACE CURRENTS AND CHLOROPHYLL CONCENTRATION MAPS

Abstract

Submesoscale coastal surface currents and chlorophyll concentrations at hourly and O(1)-kmresolutions, obtained from an array of high-frequency radars and geostationary ocean color imagery in a coastal region off the east coast of Korea over a period of one year (2013), are described in the frequency and wavenumber domains. The kinetic energy spectra of the surface currents in the wavenumber domain (k) become steeper at a scale of approximately 10 km from a slope of k to slopes between k and k at a length scale of 2 km. Moreover, the energy spectra of the chlorophyll exhibit anisotropy associated with bathymetric effects and regional circulation, and their decay slopes change from k to k at O(10) km scales and from k to k at O(1) km scales, which is consistent with the two-dimensional quasigeostrophic turbulence theory. The spectral decay slopes of these energy spectra show weak seasonality, which can be interpreted with the baroclinic instability in the weak seasonal mixed layer and the persistent and non-seasonal regional circulations.