aes_region.RdThe full set is `aes_region`, which has a complementary data set in longitude/latitude called `aes_region_ll`. There is also simpler version of `aes_region` with the banks and plateaus included in the larger pieces `aes_region_simple`.
These assessment regions are designed for assessing status and trends in habitats, biogeochemistry, productivity, key species and ecosystem attributes. The assessments would be targeting policy makers to describe what is happening to Southern Ocean ecosystems. The approach used here was chosen over a bioregionalisation type approach because of the difficulties in characterising a bioregion that could then have its distribution tracked through time. The approach here would assess the different attributes and how they are changing in each region. There are 19 unique classes of areas in this map in a hierarchy - four meridional sectors, three zonal divisions, and two bathymetric divisions (note that there are no regions shallower than 2000 m in the polar of the East Pacific sector).
The four sectors were derived from approximate boundaries of regions within the Southern Ocean described in the literature (Buiron et al. 2012, Constable et al. 2014). The rationale for the boundaries is as follows. Although the west Antarctic Peninsula area is connected to the Scotia Sea, descriptions in the literature separate these two parts of the system. A natural boundary would be at the Drake Passage. Another boundary which separates the Indian Sector from the Pacific was aligned just to the west of the Macquarie Ridge to take account of the oceanographic differences to the east and west of the ridge as well as the northern influences of the East Australia current. The boundaries between Atlantic and Indian sectors and the West and East Pacific sectors were derived from the eastern extent of the influence of the Weddell Gyre and the Ross Sea Gyre respectively.
Based on a northern boundary at 30°S, a middle boundary at approximately the subantarctic front and a division between waters on and off the continental shelf (around the Antarctic continent; from O’Brien et al. 209).
The definition of these regions was informed by the bioregionalisation of the Southern Ocean (Grant et al 2006). The bioregionalisation showed the interaction between the frontal zones and the annual advance and retreat of sea ice. Those results suggested that bounding higher latitudes from the subantarctic front might best encompass the higher latitude ecosystem, including the biogeochemistry.
Within each assessment region, there is a separation between the shelf and plateau areas from the deep ocean basins. This separation is at the 2000 m contour (The GEBCO_08 Grid, version 20091120, http://www.gebco.net).
Buiron D., B. Stenni, J. Chappellaz, A. Landais, M. Baumgartner, M. Bonazza, E. Capron, M. Frezzotti, M. Kageyama, B. Lemieux-Dudon, V. Masson-Delmotte, F. Parrenin, A. Schilt, E. Selmo, M. Severi, D. Swingedouw, R. Udisti. 2012. Regional imprints of millennial variability during the MIS 3 period around Antarctica. Quaternary Science Reviews 48: 99-112.
Constable A. J., J. Melbourne-Thomas, S. P. Corney, K. R. Arrigo, C. Barbraud, D. K. A. Barnes, N. L. Bindoff, P. W. Boyd, A. Brandt, D. P. Costa, A. T. Davidson, H. W. Ducklow, L. Emmerson, M. Fukuchi, J. Gutt, M. A. Hindell, E. E. Hofmann, G. W. Hosie, T. Iida, S. Jacob, N. M. Johnston, S. Kawaguchi, N. Kokubun, P. Koubbi, M.-A. Lea, A. Makhado, R. A. Massom, K. Meiners, M. P. Meredith, E. J. Murphy, S. Nicol, K. Reid, K. Richerson, M. J. Riddle, S. R. Rintoul, W. O. Smith Jr, C. Southwell, J. S. Stark, M. Sumner, K. M. Swadling, K. T. Takahashi, P. N. Trathan, D. C. Welsford, H. Weimerskirch, K. J. Westwood, B. C. Wienecke, D. Wolf-Gladrow, S. W. Wright, J. C. Xavier, and P. Ziegler. 2014. Climate change and Southern Ocean ecosystems I: how changes in physical habitats directly affect marine biota. Global Change Biology 20:3004–3025.
Grant S., A. Constable, B. Raymond, S. Doust. 2006. Bioregionalisation of the Southern Ocean: Report of Experts Workshop, WWF- Australia and ACE CRC. Hobart, Sep- tember 2006.
O’Brien P., A. Post, R. Romeyn. 2009. Antarctic-wide geomorphology as an aid to habitat mapping and locating Vulnerable Marine Ecosystems. CCAMLR Workshop on Vulnerable Marine Ecosystems, Paper WS-VME-09/10. CCAMLR, La Jolla, California, USA.