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Introduces the continent of Antarctica and some of its unique characteristics.

Australian waters contain the highest diversity of cephalopods (squid, cuttlefish and octopus) found anywhere in the world. They are highly significant ecologically, both as top-level predators and as prey for numerous vertebrates, including fishes, seals, cetaceans and seabirds.Cephalopods of Australia and Sub-Antarctic Territories is a comprehensive guide covering 226 species, which represent over a quarter of the world's cephalopod fauna. With an emphasis on identification, this book includes keys, species descriptions, full-colour illustrations and distribution maps, as well as a summary of the biology and behaviour of cephalopods and fisheries information. This is an invaluable tool for researchers and fisheries experts as well as amateur naturalists, fishers and divers.

This illustrated atlas of South America and Antarctica combines maps, pictures, flags, globes, information panels, diagrams, and charts to give a complete overview of the regions.

Given that the polar regions, especially the Antarctic Peninsula, have experienced one of the largest temperature increases on Earth over the last few decades, an understanding of Antarctic climate has become more urgent. Ice shelves themselves are located at the intersection of the atmosphere, hydrosphere and the cryosphere—the air-ice-ocean boundary, and are sensitive to changes in any of these media. In addition to being particularly sensitive to changes in climate, ice shelves play an important role in controlling the flow of glaciers into the ocean, which has important implications for sea level changes. In a warming world, an increased understanding of how climate change is affecting Antarctic ice shelves is valuable for assessing vulnerable regions of the Antarctic that may be prone to further instability. This work focuses on determining the underlying climatic processes controlling energy and mass balance responsible for driving melting over ice shelves. A novel melt-magnitude retrieval method is presented that uses Moderate Resolution Imaging Spectroradiometer (MODIS)-derived near-IR reflectance coupled with ice surface temperature as a proxy for surface melt magnitude. This method has a higher spatial resolution than passive microwave melt detection, has the added benefit of retrieving melt magnitude rather than a binary melt occurrence or non-occurrence, but has a lower temporal resolution than either passive-microwave or microwave-scatterometry melt detection. This limitation is a result of the opacity of cloud cover to both visible and IR radiation, requiring more satellite overpasses to obtain spatially contiguous imagery. This work also examines several weather variables associated with a large-extent, long-duration surface melt event on the Ross Ice Shelf. It is shown that cloudy conditions coupled with increased sensible and latent heat flux to the surface were present during the event, and these conditions are consistent with those that induce surface melting. Finally, an analysis of co-occurring climate conditions and surface melting over a recent 15-year time period (1987-2002) is presented. This analysis examines surface melt extent in three regions: Ross Ice Shelf, Larsen Ice Shelf and the Amundsen-Bellingshausen Region. Self-Organizing Maps (SOMs) are used to categorize weather patterns for each December and January day during the study period, and the average surface melt extent for each SOM pattern is computed. These values are compared to average December and January surface melt extents for each region to determine the SOM patterns associated with significantly greater or significantly less melt than the 15-year average. Over the Ross region, increases in sensible and latent heat fluxes are associated with greater surface melt extent, as is the presence of cyclonic circulation in the Ross Sea that drives mild maritime air poleward. In the Larsen and Amundsen-Bellingshausen regions, radiation fluxes appear to be more closely associated with surface melt extent, although the relationship for the geographically heterogeneous Amundsen-Bellingshausen region is less clear. These results can guide future mesoscale modeling studies that will be able to more precisely determine the causative role of each atmospheric variable in generating surface melting on West Antarctic ice shelves.

AIM: For many applications in biodiversity and ecology, existing remote sensing‐derived land‐cover products have limitations due to among‐product inconsistency and their typically non‐continuous nature. Here we aim to help address these shortcomings by generating a 1‐km resolution global product that provides scale‐integrated and accuracy‐weighted consensus land‐cover information on an approximately continuous scale. LOCATION: Global. METHODS: Using a generalized classification scheme and an accuracy‐based integration approach, we integrated four global land‐cover products. We evaluated the performance of this product compared with inputs for estimating subpixel 30‐m resolution land cover. We also compared the accuracy of deductive and inductive species distribution models built with the different products for modelling the continental distributions of six avian habitat specialists. RESULTS: Our product offers accuracy‐weighted consensus information on the prevalence of 12 land‐cover classes within every nominal 1‐km pixel across the globe (except for Antarctica). Compared with the four base products, it better captures the land‐cover information contained in the fine‐grain validation data for all classes combined and for most individual classes. It also has the highest sensitivity and overall accuracy for detecting the presence of every fine‐grain land‐cover class. Both deductive and inductive models built with the consensus dataset have the highest or second highest accuracy for modelling bird species distributions. MAIN CONCLUSIONS: Our consensus product integrates the four base products and successfully maximizes accuracy and reduces errors of omission. Specifically, the consensus product reduces limitations caused by misclassifications, false absence rates and the categorical format of existing land‐cover products. Consequently, it surpasses single base products in the ability to capture subpixel land‐cover information and the utility for modelling species distributions. Both the presented methodology and the consensus product have multiple applications in biodiversity research and for understanding and modelling of global terrestrial ecosystems.

This study presents the first high-resolution orthophoto maps and digital surface models (DSMs) of the largest Argentine Islands, West Antarctica. Aerial surveys with small unmanned aerial vehicle (UAV) were performed in Austral summer, 2018, taking 10,041 aerial photographs. Accuracy requirements were ensured using ground control points (GCPs). A resolution of 3.4 and 6.8 cm/px of orthomosaics and DSMs is reached on average, and the RMS reprojection error is 0.22 m on average. We report the morphometric parameters of surveyed islands and discuss issues related to accuracy and the usage of UAVs in polar conditions. This study demonstrates that small and low cost UAVs can be successfully used in harsh polar conditions to obtain accurate orthomosaics and DSMs of mainly glaciated terrain. We provide all generated materials in full resolution available in a scientific data repository that could be used for the monitoring of ice cap changes, vegetation cover, and wildlife populations.

We present conventional and swath altimetry data from CryoSat-2, revealing a system of subglacial lakes that drained between June 2013 and January 2014 under the central part of Thwaites Glacier, West Antarctica (TWG). Much of the drainage happened in less than 6 months, with an apparent connection between three lakes spanning more than 130 km. Hydro-potential analysis of the glacier bed shows a large number of small closed basins that should trap water produced by subglacial melt, although the observed large-scale motion of water suggests that water can sometimes locally move against the apparent potential gradient, at least during lake-drainage events. This shows that there are important limitations in the ability of hydro-potential maps to predict subglacial water flow. An interpretation based on a map of the melt rate suggests that lake drainages of this type should take place every 20–80 years, depending on the connectivity of the water flow at the bed. Although we observed an acceleration in the downstream part of TWG immediately before the start of the lake drainage, there is no clear connection between the drainage and any speed change of the glacier.

Subglacial freshwater discharge from beneath Antarctic glaciers likely has a strong impact on ice shelf basal melting. However, the difficulty in directly observing subglacial flow highlights the importance of modeling these processes. We use an ocean model of the Totten Ice Shelf cavity into which we inject subglacial discharge derived from a hydrology model applied to Aurora Subglacial Basin. Our results show (a) discharge increases melting in the vicinity of the outflow region, which correlates with features observed in surface elevation maps and satellite‐derived melt maps, with implications for ice shelf stability; (b) the change in melting is driven by the formation of a buoyant plume rather than the addition of heat; and (c) the buoyant plume originating from subglacial discharge‐driven melting is far‐reaching. Basal melting induced by subglacial hydrology is thus important for ice shelf stability, but is absent from almost all ice‐ocean models. Plain Language Summary Grounding line subglacial discharge is the outflow of freshwater at the region where Antarctic ice shelves begin to float. This process is difficult to observe as the outflow region is typically below ice up to several kilometers thick. Using a computer model, we show how the outflow of this fresh water melts the underside of an Antarctic ice shelf. We demonstrate that the outflow leads to a strong increase in melting, which is driven not by the heat in the outflow, but rather by the low salinity water's buoyancy. This buoyancy leads to the formation of a plume that rapidly ascends the underside of the ice shelf and can carry even warmer water to the ice, leading to increased melting. Given that melting of ice shelves can destabilize the grounded ice upstream of the floating region, we show that the relationship between subglacial discharge and ice shelf melt is important for understanding the stability of Antarctic ice. Key Points Subglacial discharge has a strong local effect on melting beneath the Totten Ice Shelf Addition of buoyancy explains the change in melting Discharge has far‐reaching impacts due to the extent of the buoyant plume

The subglacial bed topography is critical for modelling the evolution of Thwaites Glacier in the Amundsen Sea Embayment (ASE), where rapid ice loss threatens the stability of the West Antarctic Ice Sheet. However, mapping of subglacial topography is subject to uncertainties of up to hundreds of metres, primarily due to large gaps of up to tens of kilometres in airborne ice-penetrating radar flight lines. Deterministic interpolation approaches do not reflect such spatial uncertainty. While traditional geostatistical simulations can model such uncertainty, they become difficult to apply because of the significant non-stationary spatial variation of topography over such large surface area. In this study, we develop a non-stationary multiple-point geostatistical (MPS) approach to interpolate large areas with irregular geophysical data and apply it to model the spatial uncertainty of entire ASE basal topography. We collect 166 high-quality topographic training images (TIs) of resolution 500 m to train the gap-filling of radar data gaps, thereby simulating realistic topography maps. The TIs are extensively sampled from deglaciated regions in the Arctic as well as Antarctica. To address the non-stationarity in topographic modelling, we introduce a Bayesian framework that models the posterior distribution of non-stationary TIs assigned to the local line data. Sampling from this distribution then provides candidate training images for local topographic modelling with uncertainty, constrained to radar flight line data. Compared to traditional MPS approaches that do not consider uncertain TI sampling, our approach results in a significant improvement in the topographic modelling quality and efficiency of the simulation algorithm. Finally, we simulate multiple realizations of high-resolution ASE topographic maps. We use the multiple realizations to investigate the impact of basal topography uncertainty on subglacial hydrological flow patterns.

High resolution hydrographic sections and maps of the gradient of sea surface height (SSH) reveal that the Antarctic Circumpolar Current (ACC) consists of multiple jets or frontal filaments. Here we use a 15 year time series of SSH observations to determine the circumpolar structure and distribution of the ACC fronts. The jets are consistently aligned with particular streamlines along the entire circumpolar path, confirming and extending the results of an earlier study restricted to the region south of Australia. The intensity of the fronts (as measured by the cross‐front gradient of SSH) varies along the fronts and the individual branches merge and diverge, often in response to interactions with bathymetry. Maps of absolute velocity at 1000 m depth derived from Argo trajectories confirm the existence of multiple current cores throughout the Southern Ocean. High resolution hydrographic sections and profiles of temperature and salinity from Argo floats are used to show that the front locations derived from fitting SSH contours to maps of SSH gradient are consistent with locations inferred from the traditional criteria based on water mass properties, suitably modified to account for multiple frontal branches. Three regions are examined in detail: the Crozet Plateau, the Kerguelen Plateau and the Scotia Sea. These examples show how recognition of the multiple jets of the ACC can help resolve discrepancies between previous studies of ACC fronts.