scholarly journals DOE Modeling Activities in the Antarctic/Southern Ocean Region

2014 ◽  
Author(s):  
Philip W. Jones
Keyword(s):  
Southern Ocean ◽  
Ocean Region ◽  
The Antarctic

scholarly journals Unexpectedly high ultrafine aerosol concentrations above East Antarctic sea ice

2016 ◽  
Vol 16 (4) ◽  
pp. 2185-2206 ◽  
Author(s):  
R. S. Humphries ◽  
A. R. Klekociuk ◽  
R. Schofield ◽  
M. Keywood ◽  
J. Ward ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Southern Ocean ◽  
Sea Ice ◽  
Radiative Forcing ◽  
Free Troposphere ◽  
Radiative Balance ◽  
Air Masses ◽  
Antarctic Sea Ice ◽  
Ocean Region ◽  
The Antarctic

Abstract. Better characterisation of aerosol processes in pristine, natural environments, such as Antarctica, have recently been shown to lead to the largest reduction in uncertainties in our understanding of radiative forcing. Our understanding of aerosols in the Antarctic region is currently based on measurements that are often limited to boundary layer air masses at spatially sparse coastal and continental research stations, with only a handful of studies in the vast sea-ice region. In this paper, the first observational study of sub-micron aerosols in the East Antarctic sea ice region is presented. Measurements were conducted aboard the icebreaker Aurora Australis in spring 2012 and found that boundary layer condensation nuclei (CN3) concentrations exhibited a five-fold increase moving across the polar front, with mean polar cell concentrations of 1130 cm−3 – higher than any observed elsewhere in the Antarctic and Southern Ocean region. The absence of evidence for aerosol growth suggested that nucleation was unlikely to be local. Air parcel trajectories indicated significant influence from the free troposphere above the Antarctic continent, implicating this as the likely nucleation region for surface aerosol, a similar conclusion to previous Antarctic aerosol studies. The highest aerosol concentrations were found to correlate with low-pressure systems, suggesting that the passage of cyclones provided an accelerated pathway, delivering air masses quickly from the free troposphere to the surface. After descent from the Antarctic free troposphere, trajectories suggest that sea-ice boundary layer air masses travelled equatorward into the low-albedo Southern Ocean region, transporting with them emissions and these aerosol nuclei which, after growth, may potentially impact on the region's radiative balance. The high aerosol concentrations and their transport pathways described here, could help reduce the discrepancy currently present between simulations and observations of cloud and aerosol over the Southern Ocean.

scholarly journals Unexpectedly high ultrafine aerosol concentrations above East Antarctic sea-ice

2015 ◽  
Vol 15 (20) ◽  
pp. 29125-29170 ◽  
Author(s):  
R. S. Humphries ◽  
A. R. Klekociuk ◽  
R. Schofield ◽  
M. Keywood ◽  
J. Ward ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Southern Ocean ◽  
Sea Ice ◽  
Radiative Properties ◽  
Free Troposphere ◽  
Air Masses ◽  
Antarctic Sea Ice ◽  
Ocean Region ◽  
The Antarctic ◽  
Natural Aerosol

Abstract. The effect of aerosols on clouds and their radiative properties is one of the largest uncertainties in our understanding of radiative forcing. A recent study has concluded that better characterisation of pristine, natural aerosol processes leads to the largest reduction in these uncertainties. Antarctica, being far from anthropogenic activities, is an ideal location for the study of natural aerosol processes. Aerosol measurements in Antarctica are often limited to boundary layer air-masses at spatially sparse coastal and continental research stations, with only a handful of studies in the sea ice region. In this paper, the first observational study of sub-micron aerosols in the East Antarctic sea ice region is presented. Measurements were conducted aboard the ice-breaker Aurora Australis in spring 2012 and found that boundary layer condensation nuclei (CN3) concentrations exhibited a five-fold increase moving across the Polar Front, with mean Polar Cell concentrations of 1130 cm−3 – higher than any observed elsewhere in the Antarctic and Southern Ocean region. The absence of evidence for aerosol growth suggested that nucleation was unlikely to be local. Air parcel trajectories indicated significant influence from the free troposphere above the Antarctic continent, implicating this as the likely nucleation region for surface aerosol, a similar conclusion to previous Antarctic aerosol studies. The highest aerosol concentrations were found to correlate with low pressure systems, suggesting that the passage of cyclones provided an accelerated pathway, delivering air-masses quickly from the free-troposphere to the surface. After descent from the Antarctic free troposphere, trajectories suggest that sea ice boundary layer air-masses travelled equator-ward into the low albedo Southern Ocean region, transporting with them emissions and these aerosol nuclei where, after growth, may potentially impact on the region's radiative balance. The high aerosol concentrations and their transport pathways described here, could help reduce the discrepancy currently present between simulations and observations of cloud and aerosol over the Southern Ocean.

Conservation in the Antarctic

1977 ◽  
Vol 279 (963) ◽  
pp. 97-104 ◽  
Keyword(s):  
Southern Ocean ◽  
Control Measures ◽  
Falkland Islands ◽  
Voluntary Agreement ◽  
South Georgia ◽  
Tristan Da Cunha ◽  
Conservation Measures ◽  
Antarctic Seals ◽  
Antarctic Treaty ◽  
The Antarctic

Formidable legal and administrative complexities arise from conflicting claims to jurisdiction and the continued absence of generally recognized sovereignty over much of the region. Existing conservation measures fall into three groups: elaborate laws made by governments claiming Antarctic territories, more restricted laws, and simple instructions for particular expeditions. The Antarctic Treaty, 1959, made it possible to begin coordinating all these separate instruments. No claimed jurisdiction has been surrendered or recognized: each government has started to harmonize its own control measures with the ‘Agreed Measures for the Conservation of Antarctic Fauna and Flora’, 1964. This scheme applied only to land areas and has since been evolving in the light of experience. Although not yet formally approved by all the governments concerned, it is working effectively by voluntary agreement. Different approaches are necessary for conservation of Southern Ocean resources, especially krill. A start has been made with the ‘ Convention for the Conservation of Antarctic Seals’, 1972. There are many outstanding problems: all require effective cooperation between scientific and legal advisers, diplomats and politicians. Mention is made of recent British conservation legislation for South Georgia, the Falkland Islands and the Tristan da Cunha group. Some of the next steps are outlined.

Movements of southern elephant seals

1996 ◽  
Vol 74 (8) ◽  
pp. 1485-1496 ◽  
Author(s):  
B. J. McConnell ◽  
M. A. Fedak
Keyword(s):  
Southern Ocean ◽  
Continental Shelf ◽  
Antarctic Peninsula ◽  
Average Rate ◽  
Stationary Phases ◽  
Mirounga Leonina ◽  
Elephant Seals ◽  
South Georgia ◽  
Southern Elephant Seals ◽  
The Antarctic

Twelve southern elephant seals (Mirounga leonina) were tracked for an average of 119 days as they left their breeding or moulting beaches on the island of South Georgia between 1990 and 1994. Females travelled either eastward up to 3000 km away to the open Southern Ocean or to the continental shelf on or near the Antarctic Peninsula. Males either stayed close to South Georgia or used South Georgia as a base for shorter trips. The females all left South Georgia in a directed manner at an average rate of 79.4 km/day over at least the first 15 days. Thereafter travel was interrupted by bouts of slower travel or stationary phases. The latter were localized at sites on the continental shelf or along its edge. Three seals that were tracked over more than one season repeated their outward direction of travel and used some of the same sites in subsequent years. The magnitude of the movements makes most of the Southern Ocean potentially available to elephant seals.

Developments in Simulating and Parameterizing Interactions Between the Southern Ocean and the Antarctic Ice Sheet

2017 ◽  
Vol 3 (4) ◽  
pp. 316-329 ◽  
Author(s):  
Xylar S. Asay-Davis ◽  
Nicolas C. Jourdain ◽  
Yoshihiro Nakayama
Keyword(s):  
Southern Ocean ◽  
Ice Sheet ◽  
Antarctic Ice Sheet ◽  
The Antarctic

New directional wave observations from CFOSAT : impact on ocean/wave coupling in the Southern Ocean

2021 ◽  
Author(s):  
Lotfi Aouf ◽  
Daniele Hauser ◽  
Stephane Law-Chune ◽  
Bertrand chapron ◽  
Alice Dalphinet ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Surface Wind ◽  
Bias Reduction ◽  
Ocean Wave ◽  
Wave Number ◽  
Geophysical Research ◽  
Wave Coupling ◽  
Ocean Region ◽  
Directional Wave ◽  
The Impact

<p>The Southern ocean is a complex ocean region with uncertainties related to surface wind forcing and fluxes exchanges at the air/sea interface. The improvement of wind wave generation in this ocean region is crucial for climate studies. With CFOSAT satellite mission, the SWIM instrument provides directional wave spectra for wavelengths from 70 to 500 m, which shed light on the role of correcting the wave direction and peak wave number of dominant wave trains in the wind-waves growth phase. This consequently induced a better energy transfer between waves and a significant bias reduction of wave height in the Southern Ocean (Aouf et al. 2020). The objective of this work is to extend the analysis of the impact of the assimilation of wave number components from SWIM wave partitions on the ocean/wave coupling. To this end, coupled simulations of the wave model MFWAM and the ocean model NEMO are performed during the southern winter period of 2019 (May-July). We have examined the MFWAM/NEMO coupling with and without the assimilation of the SWIM mean wave number components. Several coupling processes related to Stokes drift, momentum flux stress and wave breaking inducing turbulence in the ocean mixing layer have been analyzed. We also compared the coupled runs with a control run without wave forcing in order to evaluate the impact of the assimilation. The results of coupled simulations have been validated with satellite Sea Surface Temperature and available surface currents data over the southern ocean. We also investigated the impact of the assimilation during severe storms with unlimited fetch conditions.</p><p>Further discussions and conclusions will be commented in the final paper.</p><p>Aouf L., New directional wave satellite observations : Towards improved wave forecasting and climate description in Southern Ocean, Geophysical Research Letters, DOI: 10.1029/2020GL091187 (in production).</p><p> </p><div> <div> <div></div> <div>What do you want to do ?</div> New mail</div> </div><div><img></div>

Molecular systematics of Thouarella (Octocorallia:Primnoidae) with the description of three new species from the Southern Ocean based on combined molecular and morphological evidence

2021 ◽  
Author(s):  
Mónica Núñez-Flores ◽  
Daniel Gomez-Uchida ◽  
Pablo J. López-González
Keyword(s):  
New Species ◽  
Southern Ocean ◽  
Species Delimitation ◽  
Nuclear Dna ◽  
Phylogenetic Analyses ◽  
Weddell Sea ◽  
Morphological Evidence ◽  
Three New Species ◽  
Taxonomic Framework ◽  
The Antarctic

Thouarella Gray, 1870, is one of the most speciose genera among gorgonians of the family Primnoidae (Cnidaria:Octocorallia:Anthozoa), being remarkably diverse in the Antarctic and sub-Antarctic seafloor. However, their diversity in the Southern Ocean is likely underestimated. Phylogenetic analyses of mitochondrial and nuclear DNA markers were integrated with species delimitation approaches as well as morphological colonial and polyps features and skeletal SEM examinations to describe and illustrate three new species within Thouarella, from the Weddell Sea, Southern Ocean: T. amundseni sp. nov., T. dolichoespinosa sp. nov. and T. pseudoislai sp. nov. Our species delimitation results suggest, for the first time, the potential presence of Antarctic and sub-Antarctic cryptic species of primnoids, based on the likely presence of sibling species within T. undulata and T. crenelata. With the three new species here described, the global diversity of Thouarella has increased to 41 species, 15 of which are endemic to the Antarctic and sub-Antarctic waters. Consequently, our results provide new steps for uncovering the shelf benthonic macrofauna’s hidden diversity in the Southern Ocean. Finally, we recommend using an integrative taxonomic framework in this group of organisms and species delimitation approaches because the distinctions between some Thouarella species based only on a superficial examination of their macro- and micromorphological features is, in many cases, limited.

Water Column Stratification in the Antarctic Zone of the Southern Ocean During the Mid-Pleistocene Climate Transition

2018 ◽  
Vol 33 (5) ◽  
pp. 432-442 ◽  
Author(s):  
Katharina Billups ◽  
Kelsee York ◽  
Louisa I. Bradtmiller
Keyword(s):  
Southern Ocean ◽  
Water Column ◽  
Water Column Stratification ◽  
Pleistocene Climate ◽  
Climate Transition ◽  
The Antarctic
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