110,472 research outputs found
Deep boundary current disintegration in Drake Passage
No full textThe fate of a deep boundary current that originates in the Southeast Pacific and flows southward along the continental slope of South America is elucidated. The current transports poorly ventilated water of low salinity (a type of Pacific Deep Water; PDW), into Drake Passage. East of Drake Passage, the boundary current breaks into fresh anticyclonic eddies, nine examples of which were observed in mooring data from December 2009 to March 2012. The observed eddies appear to originate mainly from a topographic separation point close to 60°W, have typical diameters of 20–60 km and accompanying Rossby numbers of 0.1–0.3. These features are likely to be responsible for transporting PDW meridionally across the ACC, explaining the near-homogenization of Circumpolar Deep Water properties downstream of Drake Passage. This mechanism of boundary current breakdown may constitute an important process in the Southern Ocean overturning circulation
Drake Passage summary report: Cruises on RRS "James Clark Ross", 1993-2000. Drake Passage repeat hydrography: WOCE Southern Repeat Section 1b - Elephant Island to Burdwood Bank.
No full textThis report documents five early cruises in the Drake Passage annual repeat series conducted by Southampton Oceanography Centre in collaboration with the British Antarctic Survey. The series began under the auspices of the World Ocean Circulation Experiment as southern repeat section SR1b with a SeaSoar (towed undulating profiler) occupation in 1992. We document cruises from 1993 (JR0a), 1994 (JR0b), 1996 (JR16), 1997 (JR27) and 2000 (JR47). The cruises were all hydrographic CTD sections across Drake Passage between Burdwood Bank and Elephant Island, comprising 30 stations. One cruise (JR27) was occupied at higher resolution with 52 stations; also additional chemical measurements were made. On two cruises (JR16 and JR27), a lowered acoustic Doppler current profiler (ADCP) was introduced to provide full-depth water velocity profiles. Other measurements (vessel-mounted ADCP, sample salinity, navigation, expendable athythermographs, etc.) are described in context
Characterizing and following eddies in Drake Passage
No full textDrake Passage, the gap between South America and Antarctica, is a very energetic region, with strong currents and numerous eddies. These eddies are important for mixing waters across the main three fronts, and for affecting the biological productivity in the region. We use weekly maps of colour images, sea level anomaly and geostrophic velocities to characterize physical and biological activity in the region surrounding Drake Passage. In particular, we note that the largest eddy kinetic energy occurs to the east of the passage and is principally in the area bounded by the mean Subantarctic Front (SAF) and the mean Polar Front, whilst the biological productivity is highest in coastal regions, with the SAF acting as a clear southern boundary. In a number of cases, cyclonic eddies detected by altimetry also show a strong signature in ocean color. Regular XBT (eXpendable BathyThermograph) surveys provide information on sub-surface structure, confirming the altimetric identification of features and showing that they often contain water masses originating from the other side of the front
Organising the range of community mental health services
No full textOrganising the range of community mental health services
Control of Mode and Intermediate Water Mass Properties in Drake Passage by the Amundsen Sea Low
No full textThe evolution of the physical properties of Subantarctic Mode Water (SAMW) and Antarctic Intermediate Water (AAIW) in the Drake Passage region is examined on time scales down to intraseasonal, within the 1969–2009 period. Both SAMW and AAIW experience substantial interannual to interdecadal variability, significantly linked to the action of the Amundsen Sea low (ASL) in their formation areas. Observations suggest that the interdecadal freshening tendency evident in SAMW over the past three decades has recently abated, while AAIW has warmed significantly since the early 2000s. The two water masses have also experienced a substantial lightening since the start of the record. Examination of the mechanisms underpinning water mass property variability shows that SAMW characteristics are controlled predominantly by a combination of air–sea turbulent heat fluxes, cross-frontal Ekman transport of Antarctic surface waters, and the evaporation–precipitation balance in the Subantarctic zone of the southeast Pacific and Drake Passage, while AAIW properties reflect air–sea turbulent heat fluxes and sea ice formation in the Bellingshausen Sea. The recent interdecadal evolution of the ASL is consistent with both the dominance of the processes described here and the response of SAMW and AAIW on that time scale
A Comparison Of The Reflectance Characteristics Of Various Shades Of The Colors Red and Green
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The Effect of Two Tranquilizers and A Related Compound on The Rate of Fission and The Survival of Paramecium Caudatum
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