Volume Transport of the Antarctic Circumpolar Current from Bottom Pressure Measurements

Whitworth, Thomas; Peterson, Ray

doi:10.1175/1520-0485(1985)015<0810:vtotac>2.0.co;2

Cited by 247 publications

(184 citation statements)

References 0 publications

Supporting

Mentioning

158

Contrasting

Order By: Relevance

“…This value is within the uncertainty range of observational estimates (e.g., 10-20 Sv from Fieux et al 1994;Lukas et al 1996). The simulated Antarctic Circumpolar Current transport simulated is about 90 Sv at the Drake Passage, which is too weak compared to the observed estimates (e.g., 120-140 Sv from Whitworth and Peterson 1985;Read and Pollard 1993;Macdonald and Wunsch 1996). The positive and negative contours represent clockwise and counterclockwise circulations, respectively, and the shading represents the magnitude of the circulation.…”

Section: Reference Experimentsmentioning

confidence: 77%

Ocean Response to the Pinatubo and 1259 Volcanic Eruptions

Kim¹,

Kim²

2012

Ocean and Polar Research

View full text Add to dashboard Cite

: The ocean's response to the Pinatubo and 1259 volcanic eruptions was investigated using an ocean general circulation model equipped with an energy balance model. Volcanic eruptions release gases into the atmosphere which increases the aerosol optical depth and acts to reduce the incoming short-wave radiation. For example, there was a huge volcanic eruption (Pinatubo) in 1991 which reduced the global mean radiative forcing by about 3 W m −2 . Two numerical experiments were simulated. The first experiment features the Pinatubo eruption and the second experiment simulates the much larger volcanic eruption that occurred in 1259 when the radiative forcing was reduced by 7 times compared to the Pinatubo event. With the reduced radiative forcing due to the Pinatubo eruption at about 3 W m −2 and 1259 eruption at about 21 W m −2 , the global mean sea surface temperature (SST) decreased to its lowest in the second year after each event by about 0.4 o C and 1.6 o C, respectively. Sea surface salinity (SSS) increased substantially in the northern North Pacific, northern North Atlantic, and the Southern Ocean. The reduced SST together with SSS increased ocean convection, which yielded an increase in North Atlantic Deep Water, Antarctic Bottom Water, and North Pacific Intermediate Water production and their outflows. The increase in overturning circulation eventually increased the pole-ward ocean heat fluxes. In conclusion, huge volcanic eruptions perturb the ocean substantially and their hallmarks last for more than a decade, confirming the importance of volcanic eruptions in illustrating the decadal-climate variability recorded in the paleoclimate proxy data for the past million years.

show abstract

Section: Reference Experimentsmentioning

confidence: 77%

Ocean Response to the Pinatubo and 1259 Volcanic Eruptions

Kim¹,

Kim²

2012

Ocean and Polar Research

View full text Add to dashboard Cite

show abstract

“…Since the Antarctic Circumpolar Current is not fully included in the model domain, assumptions have to be made about its course at 50°S. As in Timmermann et al (2002a) and Beckmann et al (1999), transport through Drake Passage is set to 130 Sv (Whitworth and Peterson 1985). Half of this is extracted from the model domain between the east coast of South America and 30°W, and reintroduced between 120°E and 180°in the Indian Sector.…”

Section: Model Descriptionmentioning

confidence: 99%

Variability of dense water formation in the Ross Sea

Assmann

Timmermann

2005

Ocean Dynamics

View full text Add to dashboard Cite

This paper presents results from a model study of the interannual variability of high salinity shelf water (HSSW) properties in the Ross Sea. Salinity and potential temperature of HSSW formed in the western Ross Sea show oscillatory behaviour at periods of 5-6 and 9 years superimposed on long-term fluctuations. While the shorter oscillations are induced by wind variability, variability on the scale of decades appears to be related to air temperature fluctuations. At least part of the strong decrease of HSSW salinities deduced from observations for the period 1963-2000 is shown to be an aliasing artefact due to an undersampling of the periodic signal. While sea ice formation is responsible for the yearly salinity increase that triggers the formation of HSSW, interannual variability of net freezing rates hardly affects changes in the properties of the resulting water mass. Instead, results from model experiments indicate that the interannual variability of dense water characteristics is predominantly controlled by variations in the shelf inflow through a sub-surface salinity and a deep temperature signal. The origin of the variability of inflow characteristics to the Ross Sea continental shelf can be traced into the Amundsen and Bellingshausen Seas. The temperature anomalies are induced at the continental shelf break in the western Bellingshausen Sea by fluctuations of the meridional transport of circumpolar deep water with the eastern cell of the Ross Gyre. In the Amundsen Sea, upwelling due to a persistently cyclonic wind field carries the signal into the surface mixed layer, leading to fluctuations of the vertical heat flux, anomalies of brine release near the sea ice edge, and consequently to a sub-surface salinity anomaly. With the westward flowing coastal current, both the sub-surface salinity and deep temperature signals are advected onto the Ross Sea continental shelf. Convection carries the signal of salinity variability into the deep ocean, where it interacts with modified circumpolar deep water upwelled onto the continental shelf as the second source water mass of HSSW. Sea ice formation on the Ross Sea continental shelf thus drives the vertical propagation of the signal rather than determining the signal itself.

show abstract

“…The ACC transport was found to be highly correlated with the bottom pressure all around the Antarctic coast and with the winds over the circumpolar area. Early investigations of this issue date back to Wearn and Baker (1980) and Whitworth and Peterson (1985). Hughes et al (1999) offer an explanation of the largescale coherent response on the basis of the propagation characteristics of topographically modified barotropic Rossby waves described by the barotropic vorticity balance.…”

Section: Introductionmentioning

confidence: 99%

Barotropic and baroclinic processes in the transport variability of the Antarctic Circumpolar Current

Olbers

Lettmann

2007

Ocean Dynamics

View full text Add to dashboard Cite

Synoptic scale variability of the Southern Ocean wind field in the high-frequency range of barotropic Rossby waves results in transport variations of the Antarctic Circumpolar Current (ACC), which are highly coherent with the bottom pressure field all around the Antarctic continent. The coherence pattern, in contrast to the steady state ACC, is steered by the geostrophic f/ h contours passing through Drake Passage and circling closely around the continent. At lower frequencies, with interannual and decadal periods, the correlation with the bottom pressure continues, but baroclinic processes gain importance. For periods exceeding a few years, variations of the ACC transport are in geostrophic balance with the pressure field associated with the baroclinic potential energy stored in the stratification, whereas bottom pressure plays a minor role. The low-frequency variability of the ACC transport is correlated with the baroclinic state variable in the entire Southern Ocean, mediated by baroclinic topographic-planetary Rossby waves that are not bound to f/ h contours. To clarify the processes of wave dynamics and pattern correlation, we apply a circulation model with simplified physics (the barotropicbaroclinic-interaction model BARBI) and use two types of wind forcing: the National Centers for Environmental Prediction (NCEP) wind field with integrations spanning three decades and an artificial wind field constructed from the first three empirical orthogonal We analyze the spinup, trends, and variability of the model runs. Particular emphasis is placed on coherence and correlation patterns between the ACC transport, the wind forcing, the bottom pressure field and the pressure associated with the baroclinic potential energy. A stochastic dynamical model is developed that describes the dominant barotropic and baroclinic processes and represents the spectral properties for a wide range of frequencies, from monthly periods to hundreds of years.

show abstract

Volume Transport of the Antarctic Circumpolar Current from Bottom Pressure Measurements

Cited by 247 publications

References 0 publications

Ocean Response to the Pinatubo and 1259 Volcanic Eruptions

Ocean Response to the Pinatubo and 1259 Volcanic Eruptions

Variability of dense water formation in the Ross Sea

Barotropic and baroclinic processes in the transport variability of the Antarctic Circumpolar Current

Contact Info

Product

Resources

About