Structure and Variability of Mesoscale Perturbations of Ocean Currents in the Drake Passage and Scotia Sea

Abstract

Satellite altimeter observation data collected over 22 years are used to analyze the structure and variability of mesoscale fluctuations of ocean currents in the Drake Passage and Scotia Sea. Wavelet analysis of the time series of the absolute dynamic topography of the ocean surface (ADTOS) at a set of points in the study site revealed a high degree of statistical nonstationarity of these time series, which is manifested as short (a few years) intervals of intense ADTOS fluctuations separated by long intervals of weak fluctuations. Analysis of mesoscale ADTOS maps showed that the intervals of strong ocean velocity fluctuations in the vicinity of a specific location are controlled by the alternating cyclonic and anticyclonic formation of eddies and meanders by the jets of the Antarctic Circumpolar Current, intensification of the eddies followed by their decay, and the final confluence with the parent jets. In addition to statistical nonstationarity, considerable spatial variability of the statistical characteristics of mesoscale perturbations of ocean currents was revealed over scales of 150–200 km.