Observed Seasonal Evolution of the Antarctic Slope Current System off the Coast of Dronning Maud Land, East Antarctica

Lauber, Julius; de Steur, Laura; Hattermann, Tore; Darelius, Elin

doi:10.1029/2023jc020540

Cited by 3 publications

(1 citation statement)

References 70 publications

(129 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, these records all show an additional secondary temperature maximum in December-January. Lauber et al (2024) (show similar out-of-phase behavior in thermocline depth between shallow and deep isobaths just east of the Fimbul Ice Shelf near the Prime Meridian.…”

Section: Hydrography and Thermocline Depthmentioning

confidence: 75%

Observations of the Antarctic Slope Current in the Southeastern Weddell Sea: A Bottom‐Enhanced Current and Its Seasonal Variability

Darelius,

Fer,

Janout

et al. 2024

JGR Oceans

Self Cite

View full text Add to dashboard Cite

The Antarctic Slope Front and the associated Antarctic Slope Current dynamically regulate the exchanges of heat across the continental shelf break around Antarctica. Where the front is weak, relatively warm deep waters reach the ice shelf cavities, contributing to basal melting and ultimately affecting sea level rise. Here, we present new 2017–2021 records from two moorings deployed on the upper continental slope (530 and 738 m depth) just upstream of the Filchner Trough in the southeastern Weddell Sea. The structure and seasonal variability of the frontal system in this region, central to the inflow of warm water toward the large Filchner‐Ronne Ice Shelf, is previously undescribed. We use the records to describe the mean state and the seasonal variability of the regional hydrography and the southern part of the Antarctic Slope Current. We find that (a) the current is, contrary to previous assumptions, bottom‐enhanced, (b) the isotherms slope upwards toward the shelf break, and more so for warmer isotherms, and (c) the monthly mean thermocline depth is shallowest in February‐March and deepest in May‐June while (d) the current is strongest in April‐June. On monthly timescales, we show that (e) positive temperature anomalies of the de‐seasoned records are associated with weaker‐than‐average currents. We propose that the upward‐sloping isotherms are linked to the local topography and conservation of potential vorticity. Our results contribute to the understanding of how warm ocean waters propagate southward and potentially affect basal melt rates at the Filchner‐Ronne Ice Shelf.

show abstract

Section: Hydrography and Thermocline Depthmentioning

confidence: 75%

Observations of the Antarctic Slope Current in the Southeastern Weddell Sea: A Bottom‐Enhanced Current and Its Seasonal Variability

Darelius,

Fer,

Janout

et al. 2024

JGR Oceans

Self Cite

View full text Add to dashboard Cite

show abstract

Observed Pathways and Interannual Variability of the Warm Inflow Onto the Continental Shelf in the Southern Weddell Sea

Steiger,

Sallée,

Darelius

et al. 2024

JGR Oceans

View full text Add to dashboard Cite

Model projections suggest that the continental shelf in the southern Weddell Sea may experience a shift from today's near‐freezing temperature to a much warmer state, where warm water floods the shelf and basal melt rates beneath the Filchner Ronne Ice Shelf increase dramatically. Today, the Filchner Trough serves as a conduit for the southward flow of Warm Deep Water (WDW) during summer and, thus, requires continuous monitoring of its hydrographic conditions. An extensive network of moorings was installed at key sites along the inflow pathway from 2017 to 2021, to expand on existing mooring records starting in 2014. The moorings complemented with under‐ice profiling floats reveal two inflow pathways, where WDW enters along the eastern flank of the Filchner Trough as well as through a smaller trough east of there. Within the observed period, 2017 and 2018 feature anomalously warm inflows. The inflow is regulated by the heaving of isopycnals over the continental slope, and the southward propagation toward Filchner Ice Shelf is two times faster during these warm years. Furthermore, the warm years coincide with low summer sea ice concentration, which enhances surface stratification through increased freshwater input and modifies sea ice‐ocean stresses that both act to lift the warm water layer and increase the temperatures on the continental shelf. Finally, the recent record low sea ice conditions around the Antarctic emphasize the importance of our findings and raise concerns regarding a potentially increasing presence of WDW on the southern Weddell Sea shelf.

show abstract

Hydrography and circulation below Fimbulisen Ice Shelf, East Antarctica, from 14 years of moored observations

Lauber,

Hattermann,

de Steur

et al. 2024

Ocean Sci.

View full text Add to dashboard Cite

Abstract. Future mass loss from the East Antarctic Ice Sheet represents a major uncertainty in projections of future sea level rise. Recent studies have highlighted the potential vulnerability of the East Antarctic Ice Sheet to atmospheric and oceanic changes, but long-term observations inside the ice shelf cavities are rare. Here, we present new insights from observations from three oceanic moorings below Fimbulisen Ice Shelf from 2009 to 2023. We examine the characteristics of intrusions of modified Warm Deep Water (mWDW) across a sill connecting the cavity to the open ocean and investigate seasonal variability of the circulation and water masses inside the cavity using an optimum multiparameter analysis. In autumn, the water below the 345 m deep central part of the ice shelf is composed of up to 30 % solar-heated, buoyant Antarctic Surface Water (ASW), separating colder Ice Shelf Water from the ice base and affecting the cavity circulation on seasonal timescales. At depth, the occurrence of mWDW is associated with the advection of cyclonic eddies across the sill into the cavity. These eddies reach up to the ice base. The warm intrusions are observed most often from January to March and from September to November, and traces of mWDW-derived meltwater close to the ice base imply an overturning of these warm intrusions inside the cavity. We suggest that this timing is set by both the offshore thermocline depth and the interactions of the Antarctic Slope Current with the ice shelf topography over the continental slope. Our findings provide a better understanding of the interplay between shallow inflows of ASW contributions and deep inflows of mWDW for basal melting at Fimbulisen Ice Shelf, with implications for the potential vulnerability of the ice shelf to climate change.

show abstract

Observed Seasonal Evolution of the Antarctic Slope Current System off the Coast of Dronning Maud Land, East Antarctica

Cited by 3 publications

References 70 publications

Observations of the Antarctic Slope Current in the Southeastern Weddell Sea: A Bottom‐Enhanced Current and Its Seasonal Variability

Observations of the Antarctic Slope Current in the Southeastern Weddell Sea: A Bottom‐Enhanced Current and Its Seasonal Variability

Observed Pathways and Interannual Variability of the Warm Inflow Onto the Continental Shelf in the Southern Weddell Sea

Hydrography and circulation below Fimbulisen Ice Shelf, East Antarctica, from 14 years of moored observations

Contact Info

Product

Resources

About