Energy of the Jets of the Antarctic Circumpolar Current and of Their Eddies in the Surface Layer of the Southern Ocean

Oceanology - The kinetic energy of six jets of the Antarctic Circumpolar Current (ACC) and of the cyclonic and anticyclonic mesoscale eddies generated by these jets is studied in application to the...     

Currents in the Drake Passage by the observations in October–November of 2011

The currents in the Drake Passage are studied from the ADCP and CTD data acquired in a section across the Drake Passage in October-November of 2011 and from the satellite altimeter data. A complicated pattern of currents including eight jets of the Antarctic Circumpolar Current (ACC) and a system of slope and abyssal currents was found. The most interesting result is the discovery of several cyclonic and anticyclonic mesoscale eddies confined to the abyss. Some reasons explaining the generation of such eddies by the meandering of the ACC jets in the upper ocean layer are presented.     

Absolute geostrophic currents in the Drake Passage based on observations in 2003 and 2005

Geostrophic currents in the Drake Passage are studied using the data of two hydrographic sections across the passage occupied in December 2003 and November 2005 along with satellite altimetry data. A conclusion is reached that the altimetry correction of the geostrophic currents has advantages compared to the correction made on the basis of the lowered acoustic Doppler current profiler data. A number of new results about the structure and intensity of the ocean currents in the Drake Passage are obtained; the main one is the distinguishing of several abyssal currents of westward direction confined to deep passages in the bottom topography.     

Numerical modeling of currents in the Drake Passage with assimilation of the experimental data of 2003

Computation of ocean currents in the Drake Passage is carried out with variational assimilation of the data of the hydrographical section across the Drake Passage carried out on December 11–15, 2003, and other data. A stream-eddy structure of the easterly Antarctic Circumpolar Current and a westerly current on the Antarctic Slope are obtained. Water transports by the different current field components and the integral transport across the Drake Passage are estimated. The necessity of direct current measurements in the Drake Passage for a correct estimate of the transport is confirmed.     

Energy Exchange between Jets of the Antarctic Circumpolar Current and Synoptic Eddies in the Drake Passage and Scotia Sea

We study the energy exchange between jets of the Antarctic Circumpolar Current (ACC) and synoptic eddies generated by them in the surface layer of the ocean in the Drake Passage and Scotia Sea based on 22-year-long satellite altimetry time series from the French CLS Agency (DT Global–MADT–Upd product, http://www.aviso.altimetry.fr) under the assumption, based on observations, that each of the jets is confined between two fixed contour lines of the absolute dynamic topography of the ocean. We calculate and analyze the 22-year evolution of the kinetic energy of each ACC jet and cyclonic and anticyclonic eddies generated by it. We demonstrate the fundamental dependence of fluctuations in jet energy on the phase of their meander and eddy formation, as well as their back absorption by jets. We calculate the mean and extreme energetic characteristics of jets and eddies and compare the jets in terms of the intensity of the generated eddies.     

Synoptic eddies of the Subantarctic and Agulhas fronts and generation of the Antarctic Intermediate Water in the Atlantic Ocean

The concept developed in [9] and [10], according to which the Antarctic Intermediate Water is generated owing to the formation and subsequent decay of cyclonic eddies of the Subantarctic Front, is tested for the Atlantic Ocean. The cross frontal water and salt transport by the Subantarctic Front eddies and the Agulhas Front anticyclones is estimated by developing cinematic eddy models and analyzing satellite altimetry maps. Calculations of the water and salt balance for a box in the South Atlantic based on these results and various experimental data confirmed the above-mentioned concept.     

Currents in the Western Drake Passage according to the observations in January of 2010

The Western Drake Passage current system is investigated using the CTD, LADCP, and SADCP data of the cross Drake section carried out in January 2010. A complicated current structure consisting of the six Antarctic Circumpolar Current (ACC) jets as well as the system of slope and abyssal currents was revealed. The most interesting result is the identification of the abyssal quasi-geostrophic spurts in the northern part that probably are generated by abyssal eddy fragments, which are an imperative part of the meandering ACC.     

Water transport across the subantarctic front and the global ocean conveyer belt

The water transport across the Subantarctic Front involving the Ekman transport, eddy transfer, and transport by the abyssal geostrophic currents is estimated on the basis of different experimental data. This transport accounts for 14 Sv northwards in the upper ocean layer (thermocline) and the same quantity southwards in the lower layer (abyss). This quantity is equal to the magnitude of the water downwelling from the thermocline to the abyssal in the North Atlantic and North-European Basin, which is realized in the field of the Global Ocean Conveyor Belt. This result agrees with the conception according to which the oppositely directed motion of the water from the abyssal into the thermocline takes place in the Antarctic.     

Deep currents in the central part of the Drake Passage based on the data of the 2008 hydrographic survey

The currents within the junction of the Shackleton and West-Scotia ridges in the central part of the Drake Passage are studied using the data of the hydrographic survey carried out in October–November of 2008. The absolute geostrophic currents were computed by matching the CTD and LADCP data. As a result, the complicated system of deep currents conditioned by the ocean bottom’s topography was revealed and described. A new path of propagation of the Antarctic Bottom Water has been revealed.     

Currents in the Drake Passage based on observations in 2007

Currents in the Drake Passage are studied using the data of a hydrographic section along the Shackleton Transverse Ridge observed in November 2007. The distribution of the velocity component normal to the section was computed by two methods: (a) directly on the basis of the lowered acoustic Doppler current profiler (LADCP) data; (b) by the calculation of geostrophic currents based on the CTD data with estimating the depth averaged velocity on the basis of the LADCP data. The main results of the research are the relatively low estimated value of the Antarctic Circumpolar Current (ACC) transport, which accounts for 65–70% of the ACC transports in December 2003 and November 2005, and the confirmation of the existence of several abyssal currents confined to the deep passages of the bottom topography.