Modulation of the Seasonal Cycle of Antarctic Sea Ice Extent Related to the Southern Annular Mode

Doddridge, Edward W.; Marshall, John

doi:10.1002/2017gl074319

Cited by 68 publications

(74 citation statements)

References 32 publications

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“…Our results suggest that these particular models cannot simulate a 1979–2014 SAM‐induced cooling trend. We furthermore demonstrate that across all models, the seasonal SAM trends in December–May play a greater role in driving the SO SST response than the June–November SAM trends, in agreement with Purich et al () and consistent with the observed modulation of the SO seasonal sea‐ice extent (Doddridge & Marshall, ).…”

Section: Discussionmentioning

confidence: 99%

Contributions of Greenhouse Gas Forcing and the Southern Annular Mode to Historical Southern Ocean Surface Temperature Trends

Kostov

Ferreira

Armour

et al. 2018

Geophysical Research Letters

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We examine the 1979–2014 Southern Ocean (SO) sea surface temperature (SST) trends simulated in an ensemble of coupled general circulation models and evaluate possible causes of the models' inability to reproduce the observed 1979–2014 SO cooling. For each model we estimate the response of SO SST to step changes in greenhouse gas (GHG) forcing and in the seasonal indices of the Southern Annular Mode (SAM). Using these step‐response functions, we skillfully reconstruct the models' 1979–2014 SO SST trends. Consistent with the seasonal signature of the Antarctic ozone hole and the seasonality of SO stratification, the summer and fall SAM exert a large impact on the simulated SO SST trends. We further identify conditions that favor multidecadal SO cooling: (1) a weak SO warming response to GHG forcing, (2) a strong multidecadal SO cooling response to a positive SAM trend, and (3) a historical SAM trend as strong as in observations.

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Section: Discussionmentioning

confidence: 99%

Contributions of Greenhouse Gas Forcing and the Southern Annular Mode to Historical Southern Ocean Surface Temperature Trends

Kostov

Ferreira

Armour

et al. 2018

Geophysical Research Letters

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“…The strong north-westerly flow of anomalously warm and moist air into the MR contributed to the observed record low SIC and likely to the formation of the polynya (Figure 3b). Such anomalous atmospheric circulations have been noticed to have significant impacts on Antarctic sea-ice loss (Doddridge & Marshall, 2017;Ionita et al, 2018;Schlosser et al, 2018;Turner et al, 2017), however, are more pronounced on the MR and the MIZ (Figure 3b) due to its climatological low SIC ( Figure S5). The appearance of the polynya and anomalously negative SIC was associated with the SLP pattern similar to a positive phase of SAM (index of 0.42).…”

Section: Geophysical Research Lettersmentioning

confidence: 98%

Recent Reoccurrence of Large Open‐Ocean Polynya on the Maud Rise Seamount

Jena

Ravichandran

Turner

2019

Geophysical Research Letters

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Satellite observations have shown that the largest and most prolonged Maud Rise open‐ocean polynya since the 1970s appeared on 14 September 2017 (~9.3 × 103 km2) within the seasonal sea‐ice cover which expanded maximum on 1 December 2017 (~298.1 × 103 km2) and existed for 79 days. Record negative anomalies of sea‐ice concentration were observed in and around the polynya. The occurrence of the polynya was associated with a large cyclonic eddy and negative wind stress curl that facilitated melting of sea‐ice. Concurrently, a region of positive sea level pressure anomalies extended over the entire northern Weddell Sea accompanied by record low negative anomalies (deep depressions) over the southwest Weddell Sea and the Maud Rise. The atmospheric circulation anomalies advected moist‐warm air from the midlatitudes, resulted a record atmospheric warming (~11.5 °C) in the Maud Rise that favored this rare event as one of the largest open‐ocean polynyas.

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“…Both of these indices are found in the dominant time scales of variability over the Southern Ocean (Cerrone et al, ). The SAM has further been shown to modulate SIE: positive values of the summertime SAM are followed by increased SIE during autumn and negative SAM during the 2016/2017 austral summer contributed to the record minimum SIE in March 2017 (Doddridge & Marshall, ). While the SAM is seen as a driver of the interannual variability of SIE, it is the SAO and its half‐yearly cycle that is thought to play a key role in controlling the asymmetric growth‐melt cycle in Antarctic sea ice.…”

Section: Main Mechanisms Controlling the Asymmetric Antarctic Annual mentioning

confidence: 99%

Understanding the Seasonal Cycle of Antarctic Sea Ice Extent in the Context of Longer‐Term Variability

Eayrs

Holland

Francis

et al. 2019

Reviews of Geophysics

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Over the 40‐year satellite record, there has been a slight increasing trend in total annual mean Antarctic sea ice extent of approximately 1.5% per decade that is made up of the sum of significantly larger opposing regional trends. However, record increases in total Antarctic sea ice extent were observed during 2012–2014, followed by record lows (for the satellite era) through 2018. There is still no consensus on the main drivers of these trends, but it is generally believed that the atmosphere plays a significant role and that seasonal time scales and regional scale processes are important. Despite considerable yearly and regional variability, the mean seasonal cycle of growth and melt of Antarctic sea ice is strikingly consistent, with a slow growth but fast melt season. If we are to project trends in Antarctic sea ice and understand changes on longer time scales, we need to understand the mechanisms related to the seasonal cycle separately from those that drive variability. Twice‐yearly changes in the position and intensity of the zonal winds circling Antarctica are thought to drive the system by working with or against the evolving sea ice edge to slow the autumn advance and hasten the spring melt. Open water regions, created by divergence associated with the zonal winds, amplify the spring melt through increased warming of the upper ocean. Climate models fail to accurately reproduce mean Antarctic sea ice extent and overestimate its year‐to‐year variability, but they tend to capture the pattern and timing of the Antarctic seasonal cycle.

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Modulation of the Seasonal Cycle of Antarctic Sea Ice Extent Related to the Southern Annular Mode

Cited by 68 publications

References 32 publications

Contributions of Greenhouse Gas Forcing and the Southern Annular Mode to Historical Southern Ocean Surface Temperature Trends

Contributions of Greenhouse Gas Forcing and the Southern Annular Mode to Historical Southern Ocean Surface Temperature Trends

Recent Reoccurrence of Large Open‐Ocean Polynya on the Maud Rise Seamount

Understanding the Seasonal Cycle of Antarctic Sea Ice Extent in the Context of Longer‐Term Variability

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