Modeling tidal currents beneath Filchner‐Ronne Ice Shelf and on the adjacent continental shelf: Their effect on mixing and transport

Makinson, Keith; Nicholls, Keith W.

doi:10.1029/1999jc900008

Cited by 80 publications

(134 citation statements)

References 48 publications

Supporting

Mentioning

120

Contrasting

Order By: Relevance

“…This parameterization has been successful in predicting the melt rate of large ice shelves that have a relatively smooth ice base morphology and are surrounded by cold water (near-surface freezing point), such as the Filchner-Ronne Ice Shelf and Larsen C Ice Shelf (e.g., Nicholls and Jenkins 1993;Jenkins et al 2010;Nicholls et al 2012). The low melt rate regime decreases the likelihood of a rough base and of strong stratification, while the energetic tidal flows in the sector contribute to maintaining a high level of turbulence (e.g., Makinson and Nicholls 1999). Beneath these ice shelves, Nicholls and Jenkins (1993) conjectured that signatures of diffusive convection had been obliterated by the turbulence associated with the tidal motions and buoyancy-driven ascending plume.…”

Section: Discussionmentioning

confidence: 99%

Estimation of Ice Shelf Melt Rate in the Presence of a Thermohaline Staircase

Kimura

Nicholls

Venables

2015

Journal of Physical Oceanography

Self Cite

View full text Add to dashboard Cite

Diffusive convection-favorable thermohaline staircases are observed directly beneath George VI Ice Shelf, Antarctica. A thermohaline staircase is one of the most pronounced manifestations of double-diffusive convection. Cooling and freshening of the ocean by melting ice produces cool, freshwater above the warmer, saltier water, the water mass distribution favorable to a type of double-diffusive convection known as diffusive convection. While the vertical distribution of water masses can be susceptible to diffusive convection, none of the observations beneath ice shelves so far have shown signals of this process and its effect on melting ice shelves is uncertain. The melt rate of ice shelves is commonly estimated using a parameterization based on a three-equation model, which assumes a fully developed, unstratified turbulent flow over hydraulically smooth surfaces. These prerequisites are clearly not met in the presence of a thermohaline staircase. The basal melt rate is estimated by applying an existing heat flux parameterization for diffusive convection in conjunction with the measurements of oceanic conditions at one site beneath George VI Ice Shelf. These estimates yield a possible range of melt rates between 0.1 and 1.3 m yr 21, where the observed melt rate of this site is ;1.4 m yr 21. Limitations of the formulation and implications of diffusive convection beneath ice shelves are discussed.

show abstract

Section: Discussionmentioning

confidence: 99%

Estimation of Ice Shelf Melt Rate in the Presence of a Thermohaline Staircase

Kimura

Nicholls

Venables

2015

Journal of Physical Oceanography

Self Cite

View full text Add to dashboard Cite

show abstract

“…3a). The magnitude of the tidal currents are typical for the barotropic M 2 tidal current on the Weddell Sea continental shelf, but lower than that found close to the Ronne Ice Front (Robertson et al 1998;Makinson and Nicholls 1999). The inclusion of a tidal current leads to a reduction in HSSW transport into the deep cavity (TIDES ; Table 1 and Fig.…”

Section: Tidesmentioning

confidence: 95%

“…Tidal activity has been shown to play an important role in the circulation under ice shelves by modifying the mean flow through a combination of processes, including higher mixing, residual flows, and by influencing basal melting and the associated meltwater-driven thermohaline circulation beneath the ice shelf (Robertson et al 1998;Makinson and Nicholls 1999;Makinson et al 2011). The response of sub-ice shelf circulation to tidal forcing, and the relative importance of processes determining this response, is sensitive to the specific tidal regime, that is, the relative strength of background flow and tidal flow, and the location of the ice shelf relative to the critical latitude (Makinson et al 2006).…”

Section: Tidesmentioning

confidence: 99%

Eddy-Driven Exchange between the Open Ocean and a Sub–Ice Shelf Cavity

Årthun

Holland

Nicholls

et al. 2013

Journal of Physical Oceanography

Self Cite

View full text Add to dashboard Cite

The exchange between the open ocean and sub-ice shelf cavities is important to both water mass transformations and ice shelf melting. Here, the authors use a high-resolution (500 m) numerical model to investigate to which degree eddies produced by frontal instability at the edge of a polynya are capable of transporting dense high-salinity shelf water (HSSW) underneath an ice shelf. The applied surface buoyancy flux and ice shelf geometry is based on Ronne Ice Shelf in the southern Weddell Sea, an area of intense wintertime sea ice production where a flow of HSSW into the cavity has been observed. Results show that eddies are able to enter the cavity at the southwestern corner of the polynya where an anticyclonic rim current intersects the ice shelf front. The size and time scale of simulated eddies are in agreement with observations close to the Ronne Ice Front. The properties and strength of the inflow are sensitive to the prescribed total ice production, flushing the ice shelf cavity at a rate of 0.2-0.4 3 10 6 m 3 s 21 depending on polynya size and magnitude of surface buoyancy flux. Eddy-driven HSSW transport into the cavity is reduced by about 50% if the model grid resolution is decreased to 2-5 km and eddies are not properly resolved.

show abstract

“…Dense plumes are formed that slide down the continental slope. This process occurs around the Antarctic coast (Orsi et al, 1999), and particularly in the Weddell Sea and under the Ronne-Filchner Ice Shelf (Makinson and Nicholls, 1999), and in similar conditions in the Ross Sea, to form the majority of Antarctic Bottom Water. The latter spreads out into every major ocean basin except the Arctic.…”

Section: Deep-water Formation and The Conveyor Belt Theorymentioning

confidence: 99%

“…The second convection mechanism contributing to deep-water formation is through densification aided by the release of salt during sea-ice formation or sub-ice shelf accretion (Makinson and Nicholls, 1999), most typically on a continental shelf. Dense plumes are formed that slide down the continental slope.…”

Section: Deep-water Formation and The Conveyor Belt Theorymentioning

confidence: 99%

The role of the oceans in climate

Bigg

Jickells

Liss

et al. 2003

Intl Journal of Climatology

126

View full text Add to dashboard Cite

The ocean is increasingly seen as a vital component of the climate system. It exchanges with the atmosphere large quantities of heat, water, gases, particles and momentum. It is an important part of the global redistribution of heat from tropics to polar regions keeping our planet habitable, particularly equatorward of about 30°. In this article we review recent work examining the role of the oceans in climate, focusing on research in the Third Assessment Report of the IPCC and later. We discuss the general nature of oceanic climate variability and the large role played by stochastic variability in the interaction of the atmosphere and ocean. We consider the growing evidence for biogeochemical interaction of climatic significance between ocean and atmosphere. Air-sea exchange of several radiatively important gases, in particular CO 2 , is a major mechanism for altering their atmospheric concentrations. Some more reactive gases, such as dimethyl sulphide, can alter cloud formation and hence albedo. Particulates containing iron and originating over land can alter ocean primary productivity and hence feedbacks to other biogeochemical exchanges. We show that not only the tropical Pacific Ocean basin can exhibit coupled ocean-atmosphere interaction, but also the tropical Atlantic and Indian Oceans. Longer lived interactions in the North Pacific and Southern Ocean (the circumpolar wave) are also reviewed. The role of the thermohaline circulation in long-term and abrupt climatic change is examined, with the freshwater budget of the ocean being a key factor for the degree, and longevity, of change. The potential for the Mediterranean outflow to contribute to abrupt change is raised. We end by examining the probability of thermohaline changes in a future of global warming.

show abstract

Modeling tidal currents beneath Filchner‐Ronne Ice Shelf and on the adjacent continental shelf: Their effect on mixing and transport

Cited by 80 publications

References 48 publications

Estimation of Ice Shelf Melt Rate in the Presence of a Thermohaline Staircase

Estimation of Ice Shelf Melt Rate in the Presence of a Thermohaline Staircase

Eddy-Driven Exchange between the Open Ocean and a Sub–Ice Shelf Cavity

The role of the oceans in climate

Contact Info

Product

Resources

About