Tuesday 8 January 2008 à 09:53

Position of Aurora Australis

Par Sophie Mouge. Correspondent aboard the Aurora Australis

FROM: Martin Riddle
DATE: 08/01/08
REPORT (SITREP) NO.: 323
UNIVERSAL TIME: 0100
LOCAL (SHIP) TIME: 1200
AUSTRALIAN EASTERN STANDARD TIME: 1200
POSITION: -62 58S, 145 44E
HEADING: 101T
CURRENT SPEED (KNOTS): 13 Kts
DISTANCE TO NEXT WAYPOINT (NAUTICAL MILES): 20 Nm
DISTANCE COVERED LAST 24 HOURS (NAUTICAL MILES): 143.9 Nm
WEATHER CONDITIONS: Cloud clearing to leave some patchy, high cloud, good visibility, wind 5 kts from 320T
AIR TEMPERATURE: 1.0
SEA TEMPERATURE: 0.7
SEA CONDITIONS: Slight seas and low confused swell 0.5 m
ICE CONDITIONS: Open water.
REMARKS: CTD sampling of waters from the sea-surface to the seabed continues around the clock for the CASO (Climate of Antarctica and the Southern Ocean) part of V3. CASO is a major multinational project for the International Polar Year involving scientists from 18 nations and is led by Australia. CASO will provide the first circumpolar snapshot of the physical and biogeochemical state of the Southern Ocean as a benchmark for the assessment of past and future change. It will also demonstrate the feasibility of a sustained Southern Ocean observing system. CASO will continue on V6, during which a transect from Hobart to Antarctica will be sampled. On V3, CASO is focused on the region close to the Antarctic continental shelf and the fate of cold, dense 'Antarctic Bottom Water' from the Mertz Polynya. This region is one of the few places in the ocean where surface waters are made sufficiently dense to allow them to sink to the deep ocean. This transfer of water from the surface to the abyss is part of a global system of ocean currents known as the overturning or thermohaline circulation, which strongly influences Earth's climate. Our measurements on V3 are aimed at understanding how the Antarctic contribution to this global current system works and whether it is changing. We are presently re-occupying sites first measured on Aurora Australis in the 1994-5 season and are making excellent progress in unusually calm conditions. Last night we sampled the northern-most site, nearly 250 miles from the continent and are now heading east to sample some of the deepest sites which are about 4 kilometres from the surface to the seabed. Being this far north, we experienced our first, brief nightfall for the year last night.
Regards, Martin and Sarah.

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