Long-term linear meridional shift of the jet structure of the Antarctic Circumpolar Current south of Africa on the basis of the satellite altimetry data: zonal distribution

For the period of satellite altimetry observations 1993–2018, the zonal distribution of the linear meridional shift of the jet structure and the change in the intensity of currents in the sector of the Antarctic Circumpolar Current (ACC) south of Africa (9.875°W–25.125°E) were estimated. The jet structure is understood as the alternation in the meridional direction of zones of increased and decreased values of the modulus of the absolute dynamic topography (ADT) gradient, |∇ζ|. The work was carried out using the methodology developed earlier and supplemented in this article, based on the calculations of linear regressions, which also includes an assessment of calculation errors. To estimate the zonal distributions, the sector was divided into meridional bands, for each of which a calculation was carried out. The optimum width of the band is estimated at 2.5° lon. The presence of a noticeable zonal inhomogeneity in the shift of the jet structure and changes in the intensity of the currents are shown. This inhomogeneity is obviously associated with quantitative discrepancies in the calculations of these parameters with division into bands, with their subsequent averaging over the zonal series, and without division into bands. Qualitatively, the patterns of shifts in the jet structure and changes in the intensity of flows with and without separation into bands are similar.