Influence of the Southern Annular Mode on the sea ice–ocean system

Lefebvre, Wouter; Goosse, Hugues; Timmermann, Ralph; Fichefet, Thierry

doi:10.1029/2004jc002403

Cited by 263 publications

(280 citation statements)

References 56 publications

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“…The SAM is the dominant mode of atmospheric variability around Antarctica, essentially describing the north-south pressure gradient and the associated strength of the circumpolar zonal winds (e.g., Thompson and Wallace 2000). However, the SAM is additionally characterized by a significant nonannular component in the ABSL area (Lefebvre et al 2004;Fogt et al 2012a). During ENSO events, a Rossby wave train of alternating positive and negative geopotential height anomalies [the Pacific-South American (PSA) pattern] becomes established from the central Pacific to the ABS region.…”

Section: Introductionmentioning

confidence: 99%

The Influence of the Amundsen–Bellingshausen Seas Low on the Climate of West Antarctica and Its Representation in Coupled Climate Model Simulations

et al. 2013

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In contrast to earlier studies, the authors describe the climatological deep low pressure system that exists over the South Pacific sector of the Southern Ocean, referred to as the Amundsen-Bellingshausen Seas low (ABSL), in terms of its relative (rather than actual) central pressure by removing the background areaaveraged mean sea level pressure (MSLP). Doing so removes much of the influence of large-scale variability across the ABSL sector region (e.g., due to the southern annular mode), allowing a clearer understanding of ABSL variability and its effect on the regional climate of West Antarctica. Using ECMWF Interim ReAnalysis (ERA-Interim) fields, the annual cycle of the relative central pressure of the ABSL for the period from 1979 to 2011 shows a minimum (maximum) during winter (summer), differing considerably from the earlier studies based on actual central pressure, which suggests a semiannual oscillation. The annual cycle of the longitudinal position of the ABSL is insensitive to the background pressure, and shows it shifting westward from ;2508 to ;2208E between summer and winter, in agreement with earlier studies. The authors demonstrate that ABSL variability, and in particular its longitudinal position, play an important role in controlling the surface climate of West Antarctica and the surrounding ocean by quantifying its influence on key meteorological parameters. Examination of the ABSL annual cycle in 17 CMIP5 climate models run with historical forcing shows that the majority of them have definite biases, especially in terms of longitudinal position, and a correspondingly poor representation of West Antarctic climate.

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Section: Introductionmentioning

confidence: 99%

The Influence of the Amundsen–Bellingshausen Seas Low on the Climate of West Antarctica and Its Representation in Coupled Climate Model Simulations

et al. 2013

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“…This is a nonzonally symmetric component of the otherwise mostly zonal structure of the SAM as it overlies the Southern Ocean [Lefebvre et al, 2004;Thompson and Solomon, 2002]. The El Niño-Southern Oscillation phenomenon also exerts a marked influence on this region [Meredith et al, 2004;Stammerjohn et al, 2008b].…”

Section: Introductionmentioning

confidence: 99%

Feedbacks between ice cover, ocean stratification, and heat content in Ryder Bay, western Antarctic Peninsula

Venables

Meredith

2014

JGR Oceans

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A multiyear, all-season time series of water column physical properties and sea ice conditions in Ryder Bay, at the western Antarctic Peninsula (WAP), is used to assess the effects on the ocean of varying ice cover. Reduced ice cover leads to increased mixing and heat loss in the winter. The reduction in stratification persists into the following summer, preconditioning the water column to a greater vertical extent of surface-driven mixing. This leads to an increased amount of heat from insolation being mixed down, affecting approximately the top 100 m. The increased heat uptake in summer exceeds the heat lost the preceding winter, giving the initially counter-intuitive effect that enhanced winter cooling generates warmer temperatures in the following summer and autumn. This process is therefore a positive feedback on sea ice, as reduced sea ice leads to increased heat content in the ocean the following autumn. It also causes increased winter atmospheric temperatures due to the increased winter heat loss from the ocean. In the deeper part of the water column, heat and carbon stored in the Circumpolar Deep Water (CDW) layer are released by deep mixing events. At these depths, conditions are restored by advection and vertical mixing on multiyear time scales. In recent years, stronger deep mixing events in winter have led to a persistent reduction in CDW temperatures at the study site. Ocean glider data demonstrate the representativeness of these results across the wider region of Marguerite Bay, within which Ryder Bay is situated.

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“…The Southern Annular Mode index generally increased from 1970 to about 2000, and positive values have been related to an increase of greenhouse gas concentrations and depletion of stratospheric ozone (Thompson et al, 2011) There have been associated decreases in sea-ice extent and duration in the Bellingshausen Sea and Antarctic Peninsula regions of the Southern Ocean (Lefebvre et al, 2004;Stammerjohn et al, 2008aStammerjohn et al, , 2008b, and increases in sea-ice cover in the Ross Sea (Lefebvre et al, 2004;Stammerjohn Fig. 7.…”

Section: Atmospheric Conditions and Circulation In The Antarcticmentioning

confidence: 99%

Advection in polar and sub-polar environments: Impacts on high latitude marine ecosystems

Hunt

Drinkwater

Arrigo

et al. 2016

Progress in Oceanography

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a b s t r a c tWe compare and contrast the ecological impacts of atmospheric and oceanic circulation patterns on polar and sub-polar marine ecosystems. Circulation patterns differ strikingly between the north and south. Meridional circulation in the north provides connections between the sub-Arctic and Arctic despite the presence of encircling continental landmasses, whereas annular circulation patterns in the south tend to isolate Antarctic surface waters from those in the north. These differences influence fundamental aspects of the polar ecosystems from the amount, thickness and duration of sea ice, to the types of organisms, and the ecology of zooplankton, fish, seabirds and marine mammals. Meridional flows in both the North Pacific and the North Atlantic oceans transport heat, nutrients, and plankton northward into the Chukchi Sea, the Barents Sea, and the seas off the west coast of Greenland. In the North Atlantic, the advected heat warms the waters of the southern Barents Sea and, with advected nutrients and plankton, supports immense biomasses of fish, seabirds and marine mammals. On the Pacific side of the Arctic, cold waters flowing northward across the northern Bering and Chukchi seas during winter and spring limit the ability of boreal fish species to take advantage of high seasonal production there. Southward flow of cold Arctic waters into sub-Arctic regions of the North Atlantic occurs mainly through Fram Strait with less through the Barents Sea and the Canadian Archipelago. In the Pacific, the transport of Arctic waters and plankton southward through Bering Strait is minimal.In the Southern Ocean, the Antarctic Circumpolar Current and its associated fronts are barriers to the southward dispersal of plankton and pelagic fishes from sub-Antarctic waters, with the consequent evolution of Antarctic zooplankton and fish species largely occurring in isolation from those to the north. The Antarctic Circumpolar Current also disperses biota throughout the Southern Ocean, and as a result, the biota tends to be similar within a given broad latitudinal band. South of the Southern Boundary of the ACC, there is a large-scale divergence that brings nutrient-rich water to the surface. This divergence, along with more localized upwelling regions and deep vertical convection in winter, generates elevated nutrient levels throughout the Antarctic at the end of austral winter. However, such elevated nutrient levels do not support elevated phytoplankton productivity through the entire Southern Ocean, as iron concentrations are rapidly removed to limiting levels by spring blooms in deep waters. However, coastal http://dx

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Influence of the Southern Annular Mode on the sea ice–ocean system

Cited by 263 publications

References 56 publications

The Influence of the Amundsen–Bellingshausen Seas Low on the Climate of West Antarctica and Its Representation in Coupled Climate Model Simulations

The Influence of the Amundsen–Bellingshausen Seas Low on the Climate of West Antarctica and Its Representation in Coupled Climate Model Simulations

Feedbacks between ice cover, ocean stratification, and heat content in Ryder Bay, western Antarctic Peninsula

Advection in polar and sub-polar environments: Impacts on high latitude marine ecosystems

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