Seasonal Relationships between Large-Scale Climate Variability and Antarctic Sea Ice Concentration

Simpkins, Graham; Ciasto, Laura M.; Thompson, David W. J.; England, Matthew H.

doi:10.1175/jcli-d-11-00367.1

Cited by 144 publications

(203 citation statements)

References 54 publications

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“…From that association, we show evidence that attributes of the sea-ice field confronting female elephant seals during negative r years might also contribute to shaping the multi-decadal population trend. The observed long-term decrease in seal abundance has coincidentally occurred at a time when SID, SIE, SIC and sea-ice motion (some of which may be linked) south of Macquarie Island have displayed positive time-series trends [9,12,14,16,38,39]. Generally, an expanding sea-ice field is confronting energy-depleted (owing to the costs of terrestrial fasting events) female elephant seals from Macquarie Island.…”

Section: (B) Multi-decadal Trend In Seal Numbersmentioning

confidence: 98%

“…However, significant change in RS SIC during the winter months (June -November) has been attributed to the SAM [16].…”

Section: (B) Multi-decadal Trend In Seal Numbersmentioning

confidence: 99%

“…By extrapolation from the ISTHMUS census data [25], we determined that there has been a considerable reduction of about 5400 breeding females for the whole ISLAND, including ISTHMUS, over the 24 year study period. Our analysis does not explicitly test multi-decadal trends in SID and the SAM against seal abundance at Macquarie Island (see [16]). However, the results of our analyses for r (above) showed increased SID had a negative influence on seal abundance.…”

Section: (B) Multi-decadal Trend In Seal Numbersmentioning

confidence: 99%

“…stronger subpolar westerly winds) positioned farther south over the continental landmass, colder Antarctic temperatures and low atmospheric pressure over the icecap. The expected intensification of the colder westerly wind field during positive SAM conditions causes Ekman drift to strengthen northward and as a result sea-ice season and area can be extended [9,14,15]; however, the current literature is inconsistent in the degree to which sea-ice trends are associated with the SAM trend [16]. The SAM also exhibits a strong non-annular component, manifested as enhanced pressure anomalies over the Amundsen Sea.…”

Section: Introductionmentioning

confidence: 99%

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Bottom-up regulation of a pole-ward migratory predator population

et al. 2014

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As the effects of regional climate change are most pronounced at polar latitudes, we might expect polar-ward migratory populations to respond as habitat suitability changes. The southern elephant seal (Mirounga leonina L.) is a pole-ward migratory species whose populations have mostly stabilized or increased in the past decade, the one exception being the Macquarie Island population which has decreased continuously over the past 50 years. To explore probable causes of this anomalous trend, we counted breeding female seals annually between 1988 and 2011 in order to relate annual rates of population change (r) to foraging habitat changes that have known connections with atmospheric variability. We found r (i) varied annually from 20.016 to 0.021 over the study period, (ii) was most effected by anomalous atmospheric variability after a 3 year time lag was introduced (R ¼ 0.51) and (iii) was associated with sea-ice duration (SID) within the seals' foraging range at the same temporal lag. Negative r years may be extrapolated to explain, at least partially, the overall trend in seal abundance at Macquarie Island; specifically, increasing SID within the seals foraging range has a negative influence on their abundance at the island. Evidence is accruing that suggests southern elephant seal populations may respond positively to a reduced sea-ice field.

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Section: (B) Multi-decadal Trend In Seal Numbersmentioning

confidence: 98%

“…However, significant change in RS SIC during the winter months (June -November) has been attributed to the SAM [16].…”

Section: (B) Multi-decadal Trend In Seal Numbersmentioning

confidence: 99%

Section: (B) Multi-decadal Trend In Seal Numbersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Bottom-up regulation of a pole-ward migratory predator population

et al. 2014

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“…Recently, observations and modelling have highlighted the importance of wind variability in accounting for the behaviour of Southern Hemisphere sea-ice 10,[15][16][17][18][19] . Originally, it was argued that trends in dynamics and thermodynamics linked to local winds were responsible for producing the regional sea-ice trends in most sectors of the Southern Ocean 16 .…”

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confidence: 99%

Sources of heterogeneous variability and trends in Antarctic sea-ice

et al. 2015

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While the Northern Hemisphere sea-ice has uniformly declined over the past several decades, the observed sea-ice in the Southern Hemisphere has exhibited regions of increase and decrease. Here we use a comprehensive set of ocean-sea-ice simulations (1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007) to elucidate the drivers of the observed heterogeneous sea-ice trends. We show wind variability is an important determinant of the heterogeneous pattern of the variability and trends in Southern Hemisphere sea-ice. Only in the West Pacific region does Southern Annular Mode wind forcing contribute significantly to the trend in sea-ice duration. El Niño Southern Oscillation wind forcing contribution to the sea-ice duration trend is confined to the Atlantic and Pacific. In the Indian Ocean, weather is a significant driver of the sea-ice duration trend. Only in the East Pacific region is wind forcing alone insufficient to give rise to the observed sea-ice decline and must be augmented by warming to reproduce the observations.

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Variability of sea‐ice in the northern Weddell Sea during the 20th century

et al. 2014

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The record of winter fast-ice in the South Orkney Islands, northern Weddell Sea, Antarctica, is over a century long and provides the longest observational record of sea-ice variability in the Southern Hemisphere. Here we present analyses of the series of fast-ice formation and breakout dates from 1903 to 2008. We show that over the satellite era (post-1979), the timing of both final autumn formation and complete spring breakout of fast-ice is representative of the regional sea-ice concentrations (SIC) in the northern Weddell Sea, and associated with atmospheric conditions in the Amundsen Sea region to the west of the Antarctic Peninsula. Variation in the fast-ice breakout date is influenced by the intensity of the westerly/ north-westerly winds associated with the Southern Annular Mode (SAM). In contrast, the date of ice formation displays correlations with regional oceanic and sea-ice conditions over the previous 18 months, which indicate a preconditioning during the previous summer and winter, and exhibits variability associated with variation in tropical Pacific sea-surface temperature (i.e., the El Niño-Southern Oscillation, ENSO). A reduction in fast-ice duration at the South Orkney Islands around the 1950s was associated with both later formation and earlier breakout. However, there were marked changes in variability (with periodicities of 3-5, 7-9, and 20 years) in each of the series and in their relationships with ENSO and SAM, indicating the need for caution in interpreting changes in ice conditions based on shorter-term satellite series.

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Seasonal Relationships between Large-Scale Climate Variability and Antarctic Sea Ice Concentration

Cited by 144 publications

References 54 publications

Bottom-up regulation of a pole-ward migratory predator population

Bottom-up regulation of a pole-ward migratory predator population

Sources of heterogeneous variability and trends in Antarctic sea-ice

Variability of sea‐ice in the northern Weddell Sea during the 20th century

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