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Identification of optical auroras caused by mantle precipitation with the aid of particle observations from DMSP satellites
Get PDFParticle observations of the Defense Meteorological Satellite Program (DMSP) show that discrete auroral structures commonly exist in the region of the plasma mantle, but the optical features of the aurora generated by particles from the plasma mantle (called ‘mantle aurora’ in this paper) have not been established. A comparison of 7-year optical auroral observations made at the Yellow River Station with conjugate particle observations obtained from the DMSP confirm that mantle auroras have common features and can be clearly identified from all-sky imager observations. The mantle auroras normally present as sporadic and weak auroral structures split poleward of the dayside auroral oval. They are observed in both the green and red lines with the intensity of the red line being greater than that of the green line. In this paper, we illustrate typical mantle auroras and provide statistics on 55 mantle aurora cases that are confirmed by particle observation by the DMSP. Statistical results show that the occurrence of the mantle aurora has no clear dependence on the IMF By and Bz conditions, but the motion of the mantle aurora strongly depends on the IMF By, which indicates that the generation of the mantle aurora is intimately related to the dayside magnetopause reconnection. With the fundamental criteria for distinguishing the mantle aurora presented in this paper, we will be able to independently identify the mantle auroras from ground optical observations. This will allow us to investigate the physical processes that occur in the plasma mantle by monitoring the evolution of the auroral forms
Marine protected areas in the Southern Ocean: status and future
Get PDFMarine protected areas (MPAs) in the Southern Ocean are receiving more and more global attention. The Southern Ocean is one of the world’s last regions not yet seriously impacted by human activities, signifying its ecological importance and unique value for scientific research. In response to climate change and growing commercial fishing interests in the Southern Ocean and their impacts on the marine ecosystem, the Commission on the Conservation of Antarctic Marine Living Resources (CCAMLR) is reacting to growing international pressure to establish a system of MPAs in the Southern Ocean to manage fisheries and conserve vital species—such as the keystone resource Antarctic krill and the dominant fish predator Antarctic toothfish—as well as to protect whole ecosystems. This review summarizes progress in the establishment of MPAs in the Southern Ocean by focusing on several major topics: (1) the current status of MPAs in the Southern Ocean; (2) the purpose and objective of MPAs in the Southern Ocean; (3) a short description of the largest high-sea MPA (the Ross Sea MPA); (4) ecological observation and monitoring for the planned MPAs in the Southern Ocean; and (5) the importance of international cooperation in the design, establishment and future management of MPAs in the Southern Ocean
Country Report 2018: Reports from the Adhering Bodies of the International Permafrost Association
Get PDFAspect sensitivity of polar mesosphere summer echoes observed with the EISCAT VHF radar
Get PDFThe European Incoherent Scatter Scientific Association (EISCAT) Very High Frequency (224 MHz) Radar has been used to investigate the aspect sensitivity of polar mesosphere summer echoes (PMSE) in the period 13–15 July 2010. The aspect sensitivity of PMSE using this radar and at such a high frequency has not been previously reported. Data concerning the aspect sensitivity of PMSE were collected by traversing the antenna beam from the zenith direction, and comparing the received power. Surprisingly, as the intensity received by the oblique beam was often larger than that of the vertical beam, suggesting the presence of tilted dusty plasma layers as a potential cause, a theoretical model was developed to confirm the existence of these layers and their formation process. The experimental results and theoretical model presented help elucidate the structural properties of the possible generation mechanism of strong radar echoes in the polar summer mesosphere region
A glacial control on the eruption rate of Mt Erebus, Antarctica
Get PDFMt Erebus is the most active Antarctic volcano, on the flanks of the world’s largest ice sheet. Despite this, the interactions between its eruptions and the ice cover have not been studied in detail. Focusing on the most recent deglaciation, we build a glacial retreat model and compare this to recent lava geochemistry measurements to investigate the processes involved. This analysis exposes a previously unknown link between Antarctic glaciation and eruptions, of vital importance to the understanding of volcanism in this context. We find that deglaciation led to rapid emptying of the shallow magma plumbing system and a resulting peak in eruption rates synchronous with ice retreat. We also find that the present day lavas do not represent steady state conditions, but originate from a source with up to 30% more partial melting than older >4 ka eruptions. This finding that deglaciation affects volcanism both on short and longer timescales may prompt a re-evaluation of eruptions in glaciated and previously glaciated terrains both in Antarctica and beyond
Determination of Arctic melt pond fraction and sea ice roughness from Unmanned Aerial Vehicle (UAV) imagery
Get PDFMelt ponds on Arctic sea ice are of great significance in the study of the heat balance in the ocean mixed layer, mass and salt balances of Arctic sea ice, and other aspects of the earth-atmosphere system. During the 7th Chinese National Arctic Research Expedition, aerial photographs were taken from an Unmanned Aerial Vehicle over an ice floe in the Canada Basin. Using threshold discrimination and three-dimensional modeling, we estimated a melt pond fraction of 1.63% and a regionally averaged surface roughness of 0.12 for the study area. In view of the particularly foggy environment of the Arctic, aerial images were defogged using an improved dark channel prior based image defog algorithm, especially adapted for the special conditions of sea ice images. An aerial photo mosaic was generated, melt ponds were identified from the mosaic image and melt pond fractions were calculated. Three-dimensional modeling techniques were used to generate a digital elevation model allowing relative elevation and roughness of the sea ice surface to be estimated. Analysis of the relationship between the distributions of melt ponds and sea ice surface roughness shows that melt ponds are smaller on sea ice with higher surface roughness, while broader melt ponds usually occur in areas where sea ice surface roughness is lower
Arctic Renewable Energy Atlas (AREA) Project: August 2018 Singapore Workshop Report
Get PDFFrom 29–31 August 2018, the Energy Studies Institute (ESI), National University of Singapore
hosted the Arctic Renewable Energy Atlas (AREA) Project workshop participants in Singapore.
Initiated by the Arctic Council’s Sustainable Development Working Group (SDWG), AREA
integrates a range of resources from maps and data to research activities and storytelling,
thereby enhancing knowledge of best practices and local action on renewable energy within
the Arctic region
Indigenous Youth, Food Knowledge & Arctic Change - EALLU
Get PDFAn Arctic Council sustainable development working group report from the EALLU project in 2015-201
The post-Paris approach to mitigating Arctic warming—perspectives from shipping emissions reduction
Get PDFThe availability of increased Arctic shipping as a consequence of sea ice decline is a regional issue that is closely linked with international climate governance and global governance of the maritime industry. Sea ice decline creates favorable circumstances for the development of merchant shipping, but is accompanied by increases in greenhouse gas emissions. Reduction of greenhouse gas emissions from the shipping industry is of utmost importance to prevent the destruction of the fragile Arctic ecosystem. This paper focuses on the core content of the Paris Agreement and suggests that the International Maritime Organization could guide the shipping industry to reach a fair agreement with states that includes market-based measures, capacity building, and voluntary actions of shipping companies as non-state actors
Metamorphism and zircon U-Pb dating of high-pressure pelitic granulites from glacial moraines in the Grove Mountains, East Antarctica
Get PDFThe Grove Mountains are an inland continuation of the Prydz Belt in East Antarctica. Detailed metamorphic petrological and zircon U-Pb geochronological studies are performed on the high-pressure (HP) pelitic granulites from glacial moraines in the Grove Mountains. The metamorphic peak mineral assemblage of the HP pelitic granulites is characterized by garnet + kyanite + K-feldspar + biotite + plagioclase + quartz, and the subsequent medium-pressure (MP) granulite facies retrogression is characterized by sillimanite replacing kyanite, the formation of the biolite + sillimanite symplectite in the matrix. These mineral assemblages and their P-T estimates based on the P-T pseudosection constructed in MnNCKFMASHT system define a clockwise P-T path involving metamorphic peak of 11.6–13.6 kbar at 817–834°C followed by a near-isothermal decompression of 6.7–7.5 kbar at 806–828°C, comparable with those of associated HP mafic granulites from glacial moraines in the Grove Mountains. Zircon U-Pb dating, coupled with available metamorphic age data obtained for HP mafic granulites, reveals HP metamorphism occurred at 540–545 Ma. Combining the previous research results, the HP pelitic granulites and contemporary HP mafic granulites were widely distributed in glacial moraines from the Grove Mountains, suggesting at least part of the Grove Subglacial Highlands underwent Pan-Afrian HP granulite facies metamorphism, which provides new evidence for a collisional tectonic setting of the Pan-Afrian Prydz Belt