Analysis of Low-Frequency Geostrophic Transport in the Southern Ocean Measurable with Ocean Bottom Pressure

Abstract:

We sought to understand the relative importance of barotropic transport as measured from bottom pressure to total transport in the Southern Ocean. We used ocean bottom pressure and velocity data from the Estimating the Circulation and Climate of the Ocean (ECCO) state estimate run at Jet Propulsion Laboratory to quantify the percentage of total transport in various areas of the Southern Ocean that can be explained by ocean bottom pressure measurements. Only low-frequency (> 1-year) transport variations from 1993 to 2011 were considered. We examined the standard deviations, correlation, and percent variance for low-pass filtered transport integrated from 65°S – 40°S for each 1° longitude from 50°E to 150°E by vertically integrating the zonal velocity, the zonal component of the bottom current, and geostrophic current from bottom pressure gradients. We found that the transport computed from bottom pressure explained more of the full transport variability than that calculated from the bottom current.