Australia: The Land Where Time Began

A biography of the Australian continent 

Polar front Around the Kerguelen Islands – Up-to-Date Determination and Associated Circulation of Surface-Subsurface Waters

Iron-rich shelf waters that circulate around the Kerguelen Islands have a crucial role in the recurrent annual spring bloom of phytoplankton, that is climatically important, over the sluggish shelf region and its plume that extends downstream along the Antarctic circumpolar flow. With regard to the Polar Front (PF) in the Kerguelen region, there is, however, a long-standing confusion as a result of the diverse suggestions that have been made in the literature for its geographical location for which the difference of latitude is extreme at more than 10^o.  Based on abundant historical hydrographic data, the in situ hydrographic and current measurements made during the KEOPS2 cruise in 2011, chlorophyll images from satellites, and surface velocity fields that were derived from altimetry, Park et al. determined and validated an up-to-date location of the PF around Kerguelen Island. They analysed artificial Lagrange particle trajectories that were computed from altimetric velocity time series, analysing the possible pathways and sources of different surface/subsurface waters that were advected into the chlorophyll bloom area off the islands to the east that were studied during the KEOPS2 cruise. The location of the PF was determined as the boundary of the Winter Water colder than 2^oC, which is also associated with a band of strong currents, appears to be controlled primarily by topography. The PF rounds the Kerguelen Islands from the south and is deflected to the north along the eastern escarpment up to the northeastern corner of the Kerguelen Plateau, from where it is retroflected southward. The major surface/subsurface waters that are present within the deep basin to the east of the Kerguelen Islands are shown to originate from the shelf around the Heard Island, and not from the shallow shelf to the north of the Kerguelen Islands.

Sources & Further reading

1. Park, Y.-H., I. Durand, E. Kestenare, G. Rougier, M. Zhou, F. d'Ovidio, C. Cotté and J.-H. Lee (2014). "Polar Front around the Kerguelen Islands: An up-to-date determination and associated circulation of surface/subsurface waters." Journal of Geophysical Research: Oceans 119(10): 6575-6592.