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A Parrot Sequoia+ multispectral camera on a Parrot Bluegrass drone registered in four spectral bands (green, red, red edge (RE), and near-infrared (NIR)) to identify glacial outflow zones and determined the meltwater turbidity values in waters in front of the following Antarctic glaciers: Ecology, Dera Icefall, Zalewski, and Krak on King George Island, Southern Shetlands was used. This process was supported by a Red-Green-Blue (RGB) colour model from a Zenmuse X5 camera on an Inspire 2 quadcopter drone. Additional surface water turbidity measurements were carried out using a Yellow Springs Instruments (YSI) sonde EXO2. From this research, it was apparent that for mapping low-turbidity and medium-turbidity waters (<70 formazinenephelometricunits (FNU)), a red spectral band should be used, since it is insensitive to possible surface ice phenomena and registers the presence of both red and white sediments. High-turbidity plumes with elevated FNU values should be identified through the NIR band. Strong correlation coefficients between the reflectance at particular bands and FNU readings (RGreen = 0.85, RRed = 0.85, REdge = 0.84, and RNIR = 0.83) are shown that multispectral mapping using Unmanned Aerial Vehicles (UAVs) can be successfully usedeven in the unfavourable weather conditions and harsh climate of Antarctica. Lastly, the movement of water masses in Admiralty Bay is briefly discussed and supported by the results from EXO2 measurements. [ABSTRACT FROM AUTHOR]

Atmospheric warming is increasing surface melting across the Antarctic Peninsula, with unknown impacts upon glacier dynamics at the ice-bed interface. Using high-resolution satellite-derived ice velocity data, optical satellite imagery and regional climate modelling, we show that drainage of surface meltwater to the bed of outlet glaciers on the Antarctic Peninsula occurs and triggers rapid ice flow accelerations (up to 100% greater than the annual mean). This provides a mechanism for this sector of the Antarctic Ice Sheet to respond rapidly to atmospheric warming. We infer that delivery of water to the bed transiently increases basal water pressure, enhancing basal motion, but efficient evacuation subsequently reduces water pressure causing ice deceleration. Currently, melt events are sporadic, so efficient subglacial drainage cannot be maintained, resulting in multiple short-lived (<6 day) ice flow perturbations. Future increases in meltwater could induce a shift to a glacier dynamic regime characterised by seasonal-scale hydrologically-driven ice flow variations. Surface meltwater is known to influence the dynamics of some glaciers and the Greenland ice sheet. Here, the authors have identified the first examples of the drainage of surface meltwater to the bed of outlet glaciers on the Antarctic Peninsula that trigger large and rapid accelerations of ice flow. [ABSTRACT FROM AUTHOR]

Monitoring variability in outlet glaciers can improve understanding of feedbacks associated with glacier calving, ocean thermal and climate changes. In this study, a comprehensive overview of dynamic changes in Dalk Glacier since 2004 was performed using multisource satellite data. Detailed measurements of the glacier extent, velocity and elevation were conducted. During 2004-2017, periodic advances and retreats of calving margins, anomalous interannual accelerations and seasonal fluctuations in surface velocity were monitored. For the front region, there were significant velocity increases (25-30 m/a) in 2007, 2012 and 2017, and velocities in the austral winter of 2016 were ~ 30 m/a lower than the velocities during the austral summer in 2017. Our study indicates that there is a significant link between disintegrations and interannual speed variations. Different levels of disintegration and margin retreat contributed to different degrees of loss in ice-shelf buttressing and caused corresponding increases in the velocities of different regions. Simultaneous speedup of the Dalk Glacier front driven by large calving events was detected in 2007. However, the time of upstream ice flow acceleration was two years later (2009). For sporadic disintegrations between 2010 and 2012, surface velocities in all regions increased correspondingly in 2012. Although the surface elevation of the ice shelf was in a relatively stable condition from 2004 to 2016, the front ice rumple of Dalk Glacier provides significant constraining effects for upstream regions and greatly destabilizes the ice tongue. We found that disintegrations occurred when the glacier front crossed the whole ice rumple (2006 and 2016) or when the atmosphere and ocean temperatures changed significantly (2009 and 2010), triggered by ocean warming and current erosion. [ABSTRACT FROM AUTHOR]

During the last twenty-five years we have observed a substantial thinning, acceleration and mass loss of Pine Island Glacier in the West Antarctic Ice Sheet. The mass loss mechanisms, such as calving, are still poorly understood and questions remain about the processes that both destabilize and stabilize the glacier. Since 2001, we have detected six major tabular calving events, increasing in number by exponential rate, with a recorded historical terminus retreat at the latest, during October 2018. We are investigating the temporal and spatial calving variability of Pine Island Ice Shelf, and the potential impact of each calving event on glacier's dynamics. In particular, we examine the role of pre-existing bottom crevasses (rifts) at the center of the ice tongue, along with the role of the lateral ice-shelf shear zones in the western and eastern region. The initial results show no significant acceleration after each calving event, indicating that the observed buttressing loss was not relevant for the glacier's dynamics. However, we observe that a small acceleration began in March 2018, likely through weakening of west lateral side. These findings indicate that the western and eastern side disintegration of the marginal ice shelf, and the ice shelf thinning play a dominate role for the increased rate of calving events and retreat of terminus position. In our experiments we use a state-of-art ice dynamics model (Úa). The results of this study will increase our knowledge for the tabular ice-shelf calving mechanism for Antarctic Glaciers, which is poorly understood and represented in numerical glacier models. [ABSTRACT FROM AUTHOR]

Pine lsland Glacier (PIG) and Thwaites Glacier (THW) in the Amundsen Sea Embayment are among the fastest changing outlet glaciers in West Antarctica. Over the last decades both glaciers have accelerated, retreated and thinned rapidly and if these changes continue, a sufficient weakening or loss of their ice shelves may result in marine ice sheet instability with substantial grounding line retreat and large consequences for global sea level. Yet, assessing how much, how fast the ice in the Amundsen Sea Embayment will change, remains a major uncertainty.In this study, we use time series of multi-source satellite imagery (i.e. Landsat, Sentinel-1, Sentinel-2, Aster, Cryosat) to show the rapid development of damage areas on the PIG and THW ice shelves that appear crucial to the future of both glaciers, but are not included in current models of their retreat. These damage areas consist of highly crevassed areas near the grounding line and of open fractures that contain dense ice melange within the shear zones of both ice shelves. The observed damage compromises the integrity of both PIG and THW ice shelves, similar to the preconditioning of the shear zones of Larsen B prior to its collapse. To assess the importance of the damage in the shear zones, a continuum damage model (CDM) was coupled to the BISICLES ice sheet model. The model was applied on an idealized marine ice sheet geometry following the MISMIP+ setup which has strong similarities to PIG conditions. Several time-dependent simulations were carried using the CDM-BISICLES model with different ocean-induced melting and damage parameterizations. In this framework, several damage scenarios were implemented by locally enhancing damage in the shear zone at the grounding line. The model results highlight the importance of damage in the shear zones as driver for ice shelf instability as they precondition the ice shelves with structural weak zones. The model results also indicate that damage enhances thinning at the grounding line, in the shear zones and of grounded ice upstream. Finally, the model shows a speedup of the glacier tongue as a result of the damage, which results in an increase in strain rate and in velocity gradients across the shear zone similar to the increasing velocity gradients across PIG and THW observed by satellites since 1992.The damage also has an important impact on the modeled grounding line retreat as the enhanced damage scenarios in the model initiate a grounding line retreat equivalent to quadrupling the oceanic melting near the grounding line from 25 to 100 m/year. This illustrates that weakening these glaciers at their most vulnerable locations is a very effective way of introducing grounding line retreat, increased ice flux and hence mass loss. The combination of these satellite observations and model results suggest that damage processes are key to ice shelf stability, grounding line retreat, and future sea level contributions from Antarctica. Moreover, they underline the need for incorporating damage processes in models to improve sea level rise projections. [ABSTRACT FROM AUTHOR]

The climate of the polar regions has dramatically changed over the last decades. This may have resulted from external forcing (e.g. from greenhouse gas emissions), but also from natural interactions between the components of the climate system (notably the atmosphere, the marine and continental cryosphere, and the ocean). Quantifying the specific contribution of each component is critical to understand decadal variability in the polar regions. Based on the complementary scientific expertise of its project partners, the PARAMOUR project aims at revealing the fundamental drivers of climate variability and assessing the predictability in the polar regions by developing and running a coupled atmosphere-ocean-ice sheet regional climate model over both hemispheres. Also, a smaller scale model setup will be developed for the Totten glacier region in Antarctica, as the Totten glacier is a highly dynamic glacier that, in recent years, has been strongly influenced by the sub-shelf intrusion of warm ocean currents. The models / components used will be the atmospheric model COSMO-CLM, the land surface model Community Land Mode, the ocean-ice model NEMO and the ice sheet models BISICLES and f.ETISh.The purpose of this poster presentation is to present the PARAMOUR project to the geo-science community. Our focus in the PARAMOUR project is on atmospheric feedback processes such as those between clouds and radiation and those between surface albedo and atmospheric processes (for example the darkening of the surface due to scouring by wind). During the course of the project we plan to i) develop a coupled atmosphere-ocean-sea ice-ice sheet model configuration for the northern hemisphere, southern hemisphere and Totten glacier region, ii) analyze the interactions between the atmosphere, ocean, sea ice and ice shelves at scales between a few hundreds of meters and a few kilometers and iii) investigate how these interactions influence the variability and predictability of the system, both in the past and in the future. [ABSTRACT FROM AUTHOR]

Extents of Antarctica's ice shelves and ice streams are sensitive indicators of glaciological and environmental change. Retreat of glacier fronts and break ups of ice shelves have been linked to oceanic and atmospheric warming. Weakening or disintegration of ice shelfs reduces buttressing of their tributary glaciers, leading to ice flow acceleration and increased sea level rise contribution. Hence, monitoring changes in ice extent is of keen interest. So far, ice fronts have mostly been delineated by manual extraction. However, this time consuming approach does no longer allow coping with the abundance of modern satellite imagery. For example, Sentinel-1 provides year-round cloudless data with weekly revisit times. Therefore, it is necessary to fully automatize ice shelf front extraction. We propose a new approach to extract calving fronts from Sentinel-1 imagery with a combination of image processing techniques. First, the deep learning architecture U-Net is used to perform a semantic segmentation on the satellite imagery. Each pixel is assigned to a probability for being either water or ice based on backscatter as well as contextual and spatial information. Second, an active contour model delineates a continuous front based on the output of the U-Net. For different test sites satisfying results are obtained. Nevertheless, still some improvements of the algorithm are necessary for example in regions where glacier margins are enclosed by ice mélange. The future implementation of the developed algorithm for Sentinel-1 imagery will provide a valuable source to monitor fluctuations in Antarctic ice shelf and glacier front locations. [ABSTRACT FROM AUTHOR]

The polar ice sheets have a controlling effect on the rise of global sea levels associated with ongoing climate change. Due to the generally low attenuation of high-frequency electromagnetic waves in ice, ground penetrating radar (GPR) signals can penetrate polar ice caps to depths of several kilometers. This makes GPR a key tool for determining the thickness of the ice sheets, investigating their internal structure, and characterizing the underlying bedrock topography. Since most GPR data are acquired in a bi-static, quasi-zero-offset manner, conventional signal processing techniques do not, however, allow for determining of the radar-wave velocity of the investigated ice masses, let alone its spatial variability. This is problematic, as this information is necessary for accurate imaging in general and for obtaining reliable estimates of the ice thickness in particular. Moreover, variations in radar-wave velocity directly reflect variations in ice water content, which is a key parameter for assessing the current state of ice sheets and for predicting their evolution. Here, we address this problem through diffraction imaging, which focuses on estimating the spatially variable radar-wave velocity from the scattered part of the GPR wavefield. To assess the potential of this method, we apply it to a 10-km-long GPR profile with a nominal center frequency of 60 MHz and a depth penetration in excess of 5 kilometers, which was acquired by the Polar Research Institute of China across the Lambert Glacier in East Antarctica. Our results suggest the presence of strong lateral radar-wave velocity variations, which, in turn, suggest correspondingly prominent variations in ice water content. The inferred radar-wave velocity model also allows for an enhanced depth imaging of the reflected part of the GPR wavefield through migration, thus corroborating its overall validity. [ABSTRACT FROM AUTHOR]

Observational records starting in the 1950s show West Antarctica is amongst the most rapidly warming regions on the planet. Together with increased intrusions of warm circumpolar deep water (CDW) onto the continental shelf due to local wind forcing (the primary mechanism in recent decades), this has resulted in enhanced surface and basal melting of floating ice shelves and an associated acceleration and thinning of West Antarctic outlet glaciers, increasing the rate of global sea level rise. In this study, it is shown that during the austral spring season, significant surface warming across West Antarctica has shifted westward to the Ross Ice Shelf in recent decades in response to enhanced cyclonic circulation over the Ross Sea. These circulation changes are caused by a Rossby wave train forced by increasing sea surface temperatures in the western tropical Pacific in the vicinity of the South Pacific Convergence Zone (SPCZ), which is tied to the springtime shift of the Interdecadal Pacific Oscillation (IPO) to its negative phase after ~1992. While the local wind trends enhance warm air advection and surface warming across the Ross Ice Shelf, the strong easterly component of the wind trends reduces the likelihood for intrusions of CDW onto the continental shelf in this region. This suggests that during spring there are competing mechanisms of surface and basal melting of the Ross Ice Shelf, both of which are closely tied to natural tropical Pacific decadal variability and a potentially important role of the SPCZ. Moreover, that the projected transition of the IPO back to its positive phase in the coming decade, though likely to reduce surface warming on the Ross Ice Shelf, could increase the risk of disintegration of Ross Sea ice shelves due to increased intrusions of CDW and enhanced basal melting. [ABSTRACT FROM AUTHOR]

Surface meltwater is widespread across the Antarctic Ice Sheet. While much recent research has focused on understanding the impact meltwater has on ice shelves, where its presence can act as a catalyst for rapid ice shelf break up, the effect of meltwater on grounded ice dynamics in Antarctica remains unknown. Using high-resolution ice velocity data derived from Sentinel 1 imagery we identify previously unobserved large (up to 100% greater than the annual mean), sudden, and synchronous accelerations in ice flow at 5 glaciers across the Antarctic Peninsula, which occur during modelled periods of surface melt. Coincident optical satellite imagery demonstrates that although much of the surface meltwater refreezes, some water appears to access the bed through crevasses and surface lake drainage. Several characteristics of the ice accelerations are consistent with the enhancement of basal motion by surface-derived meltwater reaching the ice bed. Firstly, speed-up events are often followed by short-lived reductions in ice velocity to pre-event values, and secondly, their relative magnitude is greater in regions of observed surface melt, immediately downstream of surface lake drainage events and after prolonged periods of no-or-little melt. Our data suggest that following arrival at the ice bed, meltwater is efficiently evacuated, limiting the duration of speed-up events to less than 6 days (the temporal resolution of our data). Although Antarctic Peninsula speed-up events are currently short-lived, we anticipate that predicted longer and more intense melt-seasons may lead to a shift in ice-dynamics in the region. [ABSTRACT FROM AUTHOR]

In the advent of global climate change, cryospheric research received an ever increasing attention and emerged as one of the key disciplines in climate change studies. Due to their high sensitivity to even small-scale meteorological variations, the components of the cryosphere are in fact regarded as natural indicators of climate change. One of the most alarming consequences of a changing cryosphere are melting ice masses with the potential to considerably raise global mean-sea-level and threaten low-lying coastal populations and ecosystems at all spatial scales. The Antarctic Ice Sheet (AIS) on its own holds ~91% of the global ice masses, corresponding to ~58.3 m of sea-level-equivalent (SLE) and making it the biggest potential contributor to global sea-level-rise. In order to draw valid conclusions about the state of the AIS or the behaviour and response of individual glaciers and ice shelves, detailed knowledge about mass changes and ice flow dynamics is required. Especially the measurement of ice motion is of fundamental interest to determine the rate of ice transport from the interior of the ice sheet to its margin and to quantify the spatial and temporal pattern of ice flow dynamics. Historical measurements of ice velocity were made with ground-based equipment but are impractical over the AIS due to its remoteness and vast size. The advent of spaceborne remote sensing revolutionised the ability to monitor ice dynamics in Antarctica at unprecedented spatial and temporal resolution, being of fundamental importance for an adequate prediction of future contributions to global sea-level-rise. In this study, we present the state-of-the-art of currently existing ice velocity products from satellite imagery, we summarize the spatial and temporal pattern of ice flow and we identify the main challenges and research gaps associated with ice motion over the Antarctic continent. Our analysis reveals a highly dynamic and variable flow pattern in accordance with the local and regional forcing mechanisms such as ice shelf disintegration, calving events, the bedrock geometry, oceanic and atmospheric boundary conditions, pre-frontal marine conditions or ice thinning, to only name a few. At the same time, many Antarctic glaciers were found to adjust only slowly to new environmental conditions with the dominant driving mechanisms still partly unclear and calling for increased monitoring efforts over the entire AIS. Even though numerous studies investigated the dynamical flow behaviour of Antarctic glaciers and ice shelves at local to circum-antarctic scales, many glaciers, mainly the currently stable ones on the EAIS but also several on the API and the WAIS, still lack a sufficient number of studies at high temporal and spatial resolution or with homogeneous datasets. To capture the full picture of Antarctic ice sheet motion, to better understand glacier and ice shelf response to changing boundary conditions or to separate long-term velocity signals from seasonal effects, even more uniform velocity products at high temporal resolution and with continent-wide coverage would be required. The findings of our study contribute to an improved understanding of glacier dynamics in Antarctica, being of fundamental importance for climate change studies and future sea-level-rise. [ABSTRACT FROM AUTHOR]

The article reports that the Marchant Glacier in the Royal Society Range of Antarctica was renamed the Matataua Glacier by the U.S. Board on Geographic Names in response to sexual harassment allegations against the glacier's namesake, geologist David Marchant.

The contribution of Antarctica's ice sheet to global sea-level rise depends on the very dynamic behavior of glaciers and ice shelves. One important parameter of ice-sheet dynamics is the location of glacier and ice-shelf fronts. Numerous remote sensing studies on Antarctic glacier and ice-shelf front positions exist, but no long-term record on circum-Antarctic front dynamics has been established so far. The article outlines the potential of remote sensing to map, extract, and measure calving front dynamics. Furthermore, this review provides an overview of the spatial and temporal availability of Antarctic calving front observations for the first time. Single measurements are compiled to a circum-Antarctic record of glacier and ice shelf retreat/advance. We find sufficient frontal records for the Antarctic Peninsula and Victoria Land, whereas on the West Antarctic Ice Sheet (WAIS), measurements only concentrate on specific glaciers and ice sheets. Frontal records for the East Antarctic Ice Sheet exist since the 1970s. Studies agree on the general retreat of calving fronts along the Antarctic Peninsula. East Antarctic calving fronts also showed retreating tendencies between 1970s until the early 1990s, but have advanced since the 2000s. Exceptions of this general trend are Victoria Land, Wilkes Land, and the northernmost Dronning Maud Land. For the WAIS, no clear trend in long-term front fluctuations could be identified, as observations of different studies vary in space and time, and fronts highly fluctuate. For further calving front analysis, regular mapping intervals as well as glacier morphology should be included. We propose to exploit current and future developments in Earth observations to create frequent standardized measurements for circum-Antarctic assessments of glacier and ice-shelf front dynamics in regard to ice-sheet mass balance and climate forcing. [ABSTRACT FROM AUTHOR]

This article discusses the rise of bedrock underneath glaciers in West Antarctica. The author comments on the impact this is having on the collapse of the ice sheet in the region, citing a report in the journal "Nature." The movement of the bedrock is a result of a rebound from the last Ice Age, during which the weight of the ice sheet caused the crust to form a bowl-shape.

The article provides information on the International Thwaites Glacier Collaboration, a cooperative effort between U.S. and British science agencies to study the Thwaites glacier in West Antarctica.

The article discusses the environmental impact of the melting of the Totten Glacier Ice Shelf in East Antarctica. It states that the effect of ice melting in the ocean water has been observed using bathymetry and bed topography. It adds that the warming of ocean water has been viewed as the main cause of the thinning of ice in the Totten Glacier Ice Shelf.

The article presents the Fifth Assessment Report (AR5) launched by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) on September 27, 2013. The topics discussed include warming of the atmoshphere, human influence on climate, and the melting of Mountainous, Arctic and Antarctic ice sheets. Also discussed are emission of greenhouse gases, and warming of the upper ocean layer.

Global warming is very important subject for environmental physics. Although the earth seems like inanimate, it acts just like a live mechanism which is called as Glacial-Interglacial Ice. One can consider that there are three periods for this forming, say major (100,000 years), minor (12,000 years) and smaller (1000 years) ice ages. The temperature of the earth is affected by increasing especially CO2 and other sera gases in the atmosphere. The solar radiation reflected from the earth surface cannot go back to the space due to the sera gases and is absorbed by the atmosphere. After the industrial revolution at the beginning of 20th century, especially in the last 30 years, the amount of CO2 and the other carbon gases emitted into the atmosphere has been increasing and causing natural disasters like irregular local temperature changes, floods, melting glaciers, and more powerful hurricanes. The solar radiations are mostly reflected by glaciers which are significant formations on the earth. Melting of these glaciers reduces the surface reflection and causes more absorption of solar radiation by the earth. In addition, sea level, amount of fresh water, and perceptible water vapor in the atmosphere may increase. In this study, Greenland and Antarctica glaciers' weights which press the plates downward are calculated. Melting the glaciers, the plates get rid of the pressure and rise upward over the mantle, and may cause some earthquakes, and volcanic activities such as Thoku earthquake in Japan and Eyjafjallajökull and Grimsvötn volcanos in Iceland. [ABSTRACT FROM AUTHOR]

The article examines information about alternating glacial and interglacial conditions within Antarctica that can be derived from ice cores. Records of normalized deuterium to hydrogen ratio of the ice are sensitive to air temperatures over the continent. Colder temperatures lead to greater distillation of heavy isotopes out of atmospheric moisture. To understand why glacial cycles are global, scientists may use a basic prediction that uses radiative equilibrium calculations to explore how orbital variations influence temperature and ice volume.

The article discusses living organisms and their food webs that exist in the coldest and most remote polar lakes on Earth. Free water on or under ice sheets or glaciers contains numerous species, most of which are microorganisms that exist in ecosystems thought to be indicative of climate change. Polar lakes in the Antarctic are populated by life forms such as cryptophytes, which are photosynthetic flagellates, and mixotrophic ciliates such as Mesodinium rubrum. The author also examines viral life in these lakes and discusses ways in which glaciers facilitate the existence of mini-lakes called cryoconites.

The article discusses two research papers concerning the generating of data to allow human knowledge of climatic conditions in past epochs to serve as a model for future sea-level rise resulting from global warming. The papers focus on the early to middle Pliocene Period to reconstruct Antarctica's glacial history. Observational evidence was obtained from a sediment core taken from beneath the Ross Ice Shelf, providing the authors with insight about cycles dictating summer sea ice and tectonic forces.

The article discusses the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment, which admitted that poorly characterized uncertainties have prevented a best estimate or upper bound on sea-level rise that has been catalyzed by accelerations in outland glaciers of the Greenland and Antarctic ice sheets. Research on the topic is presented chronologically, beginning with the discovery that surface meltwater can facilitate summer ice flow. The difficulty associated with accruing quantitative research is examined, and the ambiguity of the relationship between ice sheets and their underlying beds is highlighted.

The article features the study conducted on surface wind fields of the Ross Ice Shelf region in Antarctica. Researchers define four wind regimes for austral autumn including barrier wind, strong katabatic, weak katabatic and light wind wherein each was characterized through wind rose plots and corresponding sea level pressure from the Antarctic Mesoscale Prediction System (AMPS). They concluded that the research provides a better understanding of the composition of the surface wind field in the area and an insight to the characteristics of the Ross Ice Shelf air stream.

The article reports that a team of biologists have discovered life in a frozen lake two miles beneath the Antarctic ice sheet. Montana State University professor of biology John Priscu's explanation that the study's findings indicate that the microbial world has few limits. The study involves the drilling into the Antarctic ice to obtain core sample 46 centimeters long and 1.2 meters wide. Discovered in 1974, the Lake Vostok is one of the world's 10 deepest bodies of water and one of about 70 lakes underneath the glaciers of central Antarctica. The bacteria found in the lake are commonly associated with soils and could have been blown in from Patagonian deserts and then buried.