Variability of submesoscale surface currents and chlorophyll concentrations off the East Coast of Korea

Abstract

The spatial structures and temporal variability of submesoscale surface chlorophyll concentrations (CHLs) off the East Coast of Korea are examined with hourly maps of geostationary ocean color imagery CHL at a 0.5 km resolution for a period of one year (2013) in conjuction with remotely-sensed geostrophic currents, sea surface temperature, and submesoscale surface currents and numerical wind model outputs for their dynamical interpretations. The logarithmic CHLs, fridded on regular grid with a quality control flag, are well represented with the Gaussian distribution. Based on spatial covariance of log-scaled CHLs, the decorrelation length scales of the CHLs increase from 10km near the coast to 50km in the open ocean (40km from the coast) and maintain approximately 100km as a constant value in the along-shore direction. The wavenumber energy spectra of the CHLs decay with a slope of $k^{-1}$ at the scales longer than 5km and slopes of $k^{-2}$ and $k^{-3}$ at the scales shorter than 5km. Moreover, seasonal stratification have nearly negligibel influence on the decay slope of the wavenumber spectra of passive tracers. The diurnal variability of CHLs during a day depends on diurnal heat fluxes and their seasonal blooms and the difference in the near-shore and offshore regions are presented in a context of mesoscale and submesoscale variability.