Wavenumber Spectra in Drake Passage from models, altimetry, and ADCP: Connecting theory to observations
Event: 2014 Ocean Surface Topography Science Team Meeting
Session: Science Results from Satellite Altimetry: Finer scale ocean processes (mesoscale and coastal)
Presentation type: Type Oral
Contribution: PDF file
Wavenumber spectra in the upper ocean have been hypothesized to have slopes determined either by quasi-geostrophic (QG) or surface quasi-geostrophic (SQG) theory. In previous analyses of Gulf Stream observations, wavenumber spectra deviated from QG and SQG theory, and this was attributed in part to internal wave effects. The Southern Ocean offers a different environment for testing these theories: the first baroclinic Rossby radius in the Southern Ocean is estimated to be as small as 10 to 20 km (implying eddies with a typical diameter as small as 60 km), much smaller than in mid-latitudes. This study compares two high-resolution data sets with altimeter products with different intrinsic spatial resolution and different levels of smoothing. The region of focus is the Drake Passage. Shipboard acoustic Doppler current profiler (ADCP) observations with horizontal resolution of 5 km have been collected in all seasons from the US Antarctic supply vessel ARSV Laurence M. Gould since 1999, providing 288 velocity transects for use in this study. New 1-km resolution MITgcm model simulations are also considered for the Drake Passage region. We compare these with a series of high-wavenumber along-track altimeter products, including X-Track and PISTACH, which have been developed specifically to retain small scale structures for coastal studies.