Scales of horizontal density structure in the Chukchi Sea surface layer

Abstract

Horizontal density structure in the surface Chukchi Sea (in ice-free conditions) is investigated through analysis of high-resolution CTD data from two glider surveys. Temperature and salinity fields in the summer/fall surface layer indicate that horizontal temperature, salinity and density variability extends down to O(1)km submesoscales. Horizontal temperature and salinity gradients in the surface layer are universally non-compensating, with salinity dominating the density variability. Spectral slopes of k−3 (k is horizontal wavenumber) of horizontal potential density variance in the surface layer were found over 0.5 to 20km wavelengths, consistent with quasi-geostrophic turbulence scaling. The character of horizontal density structure in the surface Arctic Ocean differs from k−2 spectra commonly observed in the lower latitudes. The observed submesoscale fronts play a role in setting surface-layer properties by restratifying the surface layer, in opposition to forcing such as winds that vertically mix the surface ocean.