Preconditioning of Antarctic maximum sea ice extent by upper ocean stratification on a seasonal timescale

Su, Zhan

doi:10.1002/2017gl073236

Cited by 8 publications

(7 citation statements)

References 63 publications

(90 reference statements)

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“…There are several reasons why coastal regions near Greenland and Labrador such as Baffin Bay, Fylla Bank, and W of CB would be more prone to sea ice than a mid‐ocean site like E of CB: clearly more northerly regions would have colder temperatures and coastal regions would generally be more sheltered, allowing ocean surface stratification which is conducive to sea ice formation (Su, ). Additionally, ocean surface regions close to the Greenland shelf are likely to have much lower salinities than the open sea due to efflux of ice and water from the ice cap in summer and marine glaciers in autumn and this would make sea ice formation more likely as temperatures drop below zero.…”

Section: Discussionmentioning

confidence: 99%

Seasonal Changes in the North Atlantic Cold Anomaly: The Influence of Cold Surface Waters From Coastal Greenland and Warming Trends Associated With Variations in Subarctic Sea Ice Cover

Allan¹,

Allan

2019

JGR Oceans

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Worldwide sea surface temperatures (SST) have increased on average by about 1°C since 1900with the exception of a region of the North Atlantic subpolar gyre near 50°N which has cooled by up to 0.9°C over the same period, generating the negative feature on temperature anomaly maps which has been colloquially described by Rahmstorf et al. (2015, https://doi.org/10.1038/nclimate2554) as the "cold blob" (abbreviated here CB). This unique long-term surface cooling trend is most evident in February, but in August net warming is observed even at CB epicenter and the CB itself is reduced to a mere "warming hole." These seasonal changes in the intensity of the CB are the product of two separate factors: (1) a long-term winter cooling specific for the CB region which appears to be associated with cooling of Greenland coastal waters in autumn, plausibly linked to summer meltwater from icebergs and sea ice and (2) summer warming effects which derive from (a) dramatic reduction in summer sea ice cover in the sub-Arctic over the last 30 years that allows enhanced absorption of sunlight by the new open water in summer and (b) an unusual period of increased summer sub-Arctic ice cover in the early twentieth century, which lowers the SST baseline measured from 1900, thus increasing the calculated linear rate of change of SST with time. Both of these effects could contribute to the observed Arctic amplification of warming. Plain Language SummaryIn a world which has notably warmed by about 1°C over the last 100 years, the "cold blob" represents a unique ocean surface region in the central North Atlantic which paradoxically has cooled by almost 1°C over the same period. We show here that the intensity and coherence of the cold blob is greatest in winter, but its development appears to be connected with a surface cooling of water near the SE coast of Greenland in late autumn. This pool of cold water is likely to have its origin in summer meltwater from the Greenland ice sheet and sea-ice and we suggest ways in which it could reach and sustain the cold blob. In summer the cold blob disappears because it is overwhelmed by warming influences associated with past and current reductions in sea ice cover in the coastal sub-Arctic regions of the NW Atlantic. These warming influences associated with reductions in sea ice are part of the reason why Arctic temperatures have recently risen faster than anywhere else.

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Section: Discussionmentioning

confidence: 99%

Seasonal Changes in the North Atlantic Cold Anomaly: The Influence of Cold Surface Waters From Coastal Greenland and Warming Trends Associated With Variations in Subarctic Sea Ice Cover

Allan¹,

Allan

2019

JGR Oceans

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“…ECCO has been used in many previous studies, both globally and in the Southern Ocean, and has been shown to be consistent with available observations (Boland et al., 2021; ECCO Consortium, 2017a, 2017b; Forget, Campin, et al., 2015; Fukumori et al., 2017). While a range of observational data sets covering different time periods are used to constrain sea ice in ECCO, leading to variations from any particular set of observations, mean September sea ice in ECCO has been validated against satellite data previously by Su (2017). Sea ice area in the regions focused on in this study was compared against the same satellite data (Meier et al., 2021), and shown to have very similar seasonal and interannual variability with an r 2 value of at least 0.7 for each model (Figure S1, https://nsidc.org/data/g02202/versions/4).…”

Section: Methodsmentioning

confidence: 99%

Sea Ice‐Driven Variability in the Pacific Subantarctic Mode Water Formation Regions

Sanders,

Meijers,

Holland

et al. 2023

JGR Oceans

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Subantarctic Mode Water (SAMW) forms north of the Subantarctic Front, in regions of deep winter mixed layers, and is important to the absorption and storage of anthropogenic CO2 and heat. Two SAMW pools exist in the Pacific, a lighter Central mode (CPSAMW), and a denser Southeast mode (SEPSAMW). Both have experienced significant interannual variability in thickness and properties in recent years. We compute mixed layer temperature and salinity budgets for the two SAMW formation regions, to determine the relative contribution of processes driving variability in the properties of mixed layers that subduct to form SAMW. The dominant drivers of temperature and salinity variability are shown to be surface fluxes, horizontal advection, and entrainment of deeper water. Salt advection into each SAMW formation region is found to be strongly correlated with changes in sea ice area in the northern Ross Sea, with lags of up to 2 years. Further correlation is found between meridional salt advection in the southeast Pacific formation regions, and sea ice area in the northern Amundsen/Bellingshausen seas, suggesting that freshwater derived from sea ice melt reaches the SEPSAMW formation region within 6 months. In 2016, strong advective freshening of the SEPSAMW formation region, linked to increased winter sea ice in the Amundsen/Bellingshausen seas, led to anomalously fresh mixed layers. However, a regime change in Antarctic sea ice in 2016 resulted in a subsequent lack of the usual advective freshening in the SEPSAMW formation region, driving increased salinity of the mixed layer the following year.

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“…а -latitude of Т max (1) and Antarctic polar front (2); б -the same after smoothing with three years window; в -latitude of Т max (1) and sea ice extent (2); г -the same after smoothing with three years window . R is the correlation coefficient between (1) and (2) .…”

Section: выводыmentioning

confidence: 99%

“…Антарктический морской ледяной покров в период максимального развития ограничен с севера Антарктическим циркумполярным те чением и Антарктическим полярным фрон том (АПФ) и, следовательно, находится под влиянием факторов, определяющих его поло жение и интенсивность . Согласованность между максимальным распространением антарктиче ского морского льда в сентябре и положени ем переходной зоны в стратификации верхнего 100метрового слоя показана в работе [1] . При чина -разная стратификация верхнего слоя по обе стороны от переходной зоны .…”

Section: Introductionunclassified

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Influence of sea surface temperature in the tropics on the Antarctic sea ice under global warming

et al. 2019

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Sea ice fields in the Antarctic, in contrast to the Arctic ones, did not show a reduction in observed global warming, whereas the global climate models indicate its certain decrease. The purpose of the study is to explain this climatic phenomenon on the basis of the idea of joint dynamics of oceanic structures in the Southern Ocean – the Antarctic polar front and the margin of the maximum distribution of sea ice. We used data from the ERA/Interim and HadISST as well as the database on the sea ice for 1979–2017. Relationship between the SST-anomalies in low latitudes of the Northern hemisphere and positions of the Antarctic polar front and maximum sea-ice extent was investigated. It was found that locations of these structures changed under the influence of the SST anomalies in low latitudes. The results obtained confirm existence of the opposite trends in changes in the sea ice extent in the Arctic and Antarctic under the influence of the SST anomalies in the central North Atlantic Ocean. When positive, the anomalies cause a shift of the Intertropical Convergence Zone (ITCZ) and the Hadley circulation to the North, while, on the contrary, the negative anomaly promotes the corresponding shift of the Antarctic polar front, followed by the boundary of sea ice.

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Preconditioning of Antarctic maximum sea ice extent by upper ocean stratification on a seasonal timescale

Cited by 8 publications

References 63 publications

Seasonal Changes in the North Atlantic Cold Anomaly: The Influence of Cold Surface Waters From Coastal Greenland and Warming Trends Associated With Variations in Subarctic Sea Ice Cover

Seasonal Changes in the North Atlantic Cold Anomaly: The Influence of Cold Surface Waters From Coastal Greenland and Warming Trends Associated With Variations in Subarctic Sea Ice Cover

Sea Ice‐Driven Variability in the Pacific Subantarctic Mode Water Formation Regions

Influence of sea surface temperature in the tropics on the Antarctic sea ice under global warming

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