6 results
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2. Asymmetry of the Antarctic Oscillation in Austral Autumn.
- Author
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Tang, Yuheng and Duan, Anmin
- Subjects
- *
ANTARCTIC oscillation , *AUTUMN , *OCEAN temperature , *ATMOSPHERIC temperature , *SELF-organizing maps , *SEA ice - Abstract
The annular structure of Antarctic oscillation (AAO) is a research hotpot, but its asymmetry receives less attention. In this paper, the self‐organizing map method is employed to cluster the AAO patterns into symmetric and asymmetric modes in austral autumn. The asymmetry is mainly reflected in the Pacific‐Atlantic sector, and the AAO evolves toward asymmetric positive polarity, with the most pronounced asymmetry in May. Originating from near Australia, the asymmetry indicates a zonal wave train in the Pacific‐Atlantic sector. Both modeled and observed results demonstrate that the sea surface temperature anomaly in the equatorial western Pacific stimulates a local meridional circulation anomaly and induces anomalous Rossby wave sources near Australia subsequently. An anomalous wave train propagating toward the Antarctic Peninsula is formed, and the associated geopotential anomaly enhances the asymmetry of AAO. Asymmetric AAO is conducive to the Antarctic dipole, which modulates the air temperature and sea ice anomalies around Antarctica. Plain Language Summary: The zonal symmetry of the Antarctic oscillation (AAO; also named southern annular mode) is well known to researchers, while the zonal asymmetry has received less attention. We use a clustering method to cluster the AAO modes in austral autumn into symmetric modes and asymmetric modes. The asymmetry of AAO is mainly reflected in the Pacific‐Atlantic sector. The results show that the AAO mode evolves to a positive asymmetric mode, and the asymmetry is most obvious in May. Both simulations and observations suggest that this asymmetry stems from sea surface temperature anomaly in the equatorial western Pacific that stimulates an anomalous local meridional circulation near Australia, and in turn triggers an anomalous wave train propagating toward the Antarctic Peninsula. The associated geopotential anomalies enhance the asymmetry of AAO. The asymmetric AAO favors the Antarctic dipole, regulating the air temperature and sea ice anomalies around Antarctica. Key Points: Via a cluster method, we obtained the zonal asymmetric Antarctic oscillation (AAO) mode, and analyzed its trend and preferred monthThe source of its asymmetry is from the sea surface temperature anomaly in the tropical western PacificThe asymmetric AAO mode has a vital influence on the Antarctic dipole [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
3. The changing value of Antarctica to Australia's security policy.
- Author
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Bond, Isabelle and Mortensen, James
- Subjects
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CLIMATOLOGY , *NATURAL disasters , *EMERGENCY management , *ENVIRONMENTAL security , *CLIMATE change denial ,ANTARCTIC climate - Abstract
Antarctica is a crucial regulator of the world's climate, and as environmental security permeates global security, using Antarctic science to better understand climate is becoming increasingly pressing. Although the Australian Government has recognised that climate change poses 'a current and existential national security' threat and has acknowledged Antarctica's importance regarding the earth's global climate system, the focus of Australia's intelligence community pertaining to Antarctica currently remains restricted to upholding the military-security and diplomatic goals of the Antarctic Treaty System (ATS). This current focus aims to hedge against the possibility of conflict on, or over, the frozen continent via 'working the ATS', however, this paper argues that Antarctic climate science holds a greater capacity to deliver security outcomes for Australia. Antarctic climate science offers opportunities regarding intelligence for Antarctica, that is, securing Australia's Antarctic interests, as well as regarding intelligence from Antarctica; by enhancing natural disaster preparedness, bolstering broader strategic planning, as well as furthering diplomacy and the legitimisation of Australia's leadership on, and over, the frozen continent. It is recommended that the Commonwealth Government establish a climate intelligence working group to ensure the utility of climate science to security and intelligence is realised. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
4. Security challenges of Antarctica and the Southern Ocean Australia's Antarctic interests.
- Author
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Press, A. J. (Tony)
- Subjects
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NUCLEAR weapons testing , *NUCLEAR explosions , *TREATIES , *OCEAN , *COLLATERAL security - Abstract
The Antarctic Treaty has significant strategic and security interests for Australia. Australia claims 42 per cent of the continent, and the Antarctic Treaty established the area below 60o S as a non-militarised region where military manoeuvres, weapons testing and nuclear explosions are prohibited. The benefits to Australia of maintaining the strength of the Antarctic Treaty System are manifold. This paper sets out the importance to Australia of the Antarctic Treaty System; Australia's Antarctic activities; and current geopolitical tensions in the system. It argues that Australia should continue to invest practical and diplomatic efforts to secure its Antarctic interests and the strength of the System into the future. [ABSTRACT FROM AUTHOR]
- Published
- 2023
5. Assessing the maritime 'rules-based order' in Antarctica.
- Author
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Strating, Rebecca
- Subjects
UNITED Nations Convention on the Law of the Sea (1982) - Abstract
International Relations has become increasingly interested in maritime order as the oceans have emerged as a key site of strategic competition. The South China Sea has become totemic of contests between 'free' and 'closed' visions of the seas, and is viewed by some as a litmus test for China's efforts to re-write the 'rules-based order' in other maritime domains. This article examines the maritime 'rules-based order' in Antarctica, critically examining how and why the United Nations Convention on the Law of the Sea (UNCLOS) matters for the Antarctic region, the Southern Ocean and mechanisms of regional governance. This article contributes to understanding the complexity of maritime order in Antarctica by using Australia's maritime claims as a case study. Australia is the largest claimant state in Antarctica, with the Australian Antarctic Territory (AAT) constituting 42% of the landmass. This paper examines Australia's contentious maritime jurisdiction and its 'normative hedging' strategy that simultaneously asserts maritime claims and defends collective governance mechanisms, despite the apparent dissonance between these two positions. It argues that the Antarctic region has its own unique 'rules-based order' and geographic realities that complicate cross-regional comparisons, and that even so-called 'like-minded' states interpret maritime rules in different ways. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
6. The Sabrina microfloras of East Antarctica: Late Cretaceous, Paleogene or reworked?
- Author
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Macphail, Mike
- Subjects
- *
FOSSIL pollen , *EOCENE Epoch , *PALEOGENE , *CONTINENTAL margins - Abstract
The published latest Palaeocene to Early–Middle Eocene age limits of the Sabrina microfloras, offshore Aurora Subglacial Basin, East Antarctica, largely depend on 1970s age-range data for fossil pollen and spore species in the continental margin basins of southern Australia. This paper uses updated biostratigraphical data from southern Australia, including the basins closest to the Aurora Basin throughout the Late Cretaceous and Paleogene, to propose that the age of the terrestrial component of the Sabrina microfloras is Campanian to Maastrichtian, not Paleogene. However, the revised age limits do not preclude these microfloras being redeposited more or less intact during the development and expansion of ice-sheets on East Antarctica, i.e. most probably during the late Paleogene based on other evidence from East Antarctica. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
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