CCAMLR

Corrected ships heading data were used to calculate drift data for the shelf area to the west of South Georgia. The data were collected over a six-week period during 1986. A distance weighted interpolation was used to obtain tracer trajectories in this irregular data grid. The vector field is complex with no simple flow field. These data include a lot of complex process interactions. Particles getting onto the shelf become retained with little escape after a run of 100 days. Some of the trajectories are extremely complex. Particles to the north of the shelf can get up onto the shelf. Only those particles released very close to the shelf break in the south move up onto the shelf. Further south particles move to the west along the shelf.

A single time realisation of the FRAM model has been used to obtain trajectories of passive tracers. This note presents some of the analyses to provide background information on the potential transfers of krill in the Scotia Sea. More detailed presentation of the stream lines in the South Georgia region are also reported.

The paper reports work currently in progress and presents estimates for ocean circulation in the Scotia Sea. The estimates are derived from the drift rates of giant icebergs calved in the Weddell Sea since 1974. Comparison with other estimates is limited by the lack of studies reported in the literature, however, efforts to make these comparisons are in hand.

Current velocity data from a single time realisation of the FRAM model are presented for particular areas of the Scotia Sea. The regions are based on the CCAMLR sub-areas and also include a more detailed area around South Georgia. Mean current velocities have been calculated for region boundaries over the upper 250m of the water column. These have been combined with estimates of krill density and standing stocks to consider the large scale flux of krill through the regions and estimate residence times

A methodology is described which when applied to data from an acoustic survey will yield mean krill density along an arbitrary section through the survey area, giving results compatible with the specifications given in wg-krill-93 Appendix D. A program written to calculate such sections is also described and example output displayed. A similar program calculates current speeds normal to a section given an oceanographic dataset of current direction and speed. The two programs produce compatible vectors of krill density and current speed along specified sections