scholarly journals On the Detection and Long-Term Path Visualisation of A-68 Iceberg

2021 ◽  
Vol 13 (3) ◽  
pp. 460
Author(s):  
Ludwin Lopez-Lopez ◽  
Flavio Parmiggiani ◽  
Miguel Moctezuma-Flores ◽  
Lorenzo Guerrieri
Keyword(s):  
Image Processing ◽  
Ice Shelf ◽  
Sar Images ◽  
Processing Scheme ◽  
Image Contrast Enhancement ◽  
Stochastic Segmentation ◽  
Fuzzy Logic Approach ◽  
Logic Approach ◽  
The Antarctic

The article presents a methodology for examining a temporal sequence of synthetic aperture radar (SAR) images, as applied to the detection of the A-68 iceberg and its drifting trajectory. Using an improved image processing scheme, the analysis covers a period of eighteen months and makes use of a set of Sentinel-1 images. A-68 iceberg calved from the Larsen C ice shelf in July 2017 and is one of the largest icebergs observed by remote sensing on record. After the calving, there was only a modest decrease in the area (about 1%) in the first six months. It has been drifting along the east coast of the Antarctic Peninsula, and is expected to continue its path for more than a decade. It is important to track the huge A-68 iceberg to retrieve information on the physics of iceberg dynamics and for maritime security reasons. Two relevant problems are addressed by the image processing scheme presented here: (a) How to achieve quasi-automatic analysis using a fuzzy logic approach to image contrast enhancement, and (b) The use of ferromagnetic concepts to define a stochastic segmentation. The Ising equation is used to model the energy function of the process, and the segmentation is the result of a stochastic minimization.

scholarly journals SAR image observations of the A-68 iceberg drift

2020 ◽  
Author(s):  
Ludwin Lopez-Lopez ◽  
Flavio Parmiggiani ◽  
Miguel Moctezuma-Flores ◽  
Lorenzo Guerrieri
Keyword(s):  
Image Processing ◽  
Ice Shelf ◽  
Sar Images ◽  
Processing Scheme ◽  
Image Contrast Enhancement ◽  
Iceberg Drift ◽  
Stochastic Segmentation ◽  
Fuzzy Logic Approach ◽  
Logic Approach ◽  
The Antarctic

Abstract. A methodology for examining a temporal sequence of Synthetic Aperture Radar (SAR) images as applied to the detection of the A-68 iceberg and its drifting trajectory, is presented. Using an improved image processing scheme, the analysis covers a period of eighteen months and makes use of a set of Sentinel-1 images. A-68 iceberg calved from the Larsen C ice shelf in July 2017 and is one of the largest icebergs observed by remote sensing on record. After the calving, there was only a modest decrease in the area (about 1 %) in the first six months. It has been drifting along the east coast of the Antarctic Peninsula and it is expected to continue its path for more than a decade. It is important to track the huge A-68 iceberg to retrieve information on the physics of iceberg dynamics and for maritime security reasons. Two relevant problems are addressed by the image processing scheme presented here: (a) How to achieve quasi-automatic analysis using a fuzzy logic approach to image contrast enhancement, and (b) Adoption of ferromagnetic concepts to define a stochastic segmentation. The Ising equation is used to model the energy function of the process, and the segmentation is the result of a stochastic minimization.

scholarly journals Modelling the long-term response of the Antarctic ice sheet to global warming

1998 ◽  
Vol 27 ◽  
pp. 161-168 ◽  
Author(s):  
Roland C. Warner ◽  
W.Κ. Budd
Keyword(s):  
Global Warming ◽  
Mass Loss ◽  
Ice Sheet ◽  
Ice Shelf ◽  
Antarctic Ice Sheet ◽  
Ice Shelves ◽  
Basal Melting ◽  
The Antarctic ◽  
Term Response

The primary effects of global warming on the Antarctic ice sheet can involve increases in surface melt for limited areas at lower elevations, increases in net accumulation, and increased basal melting under floating ice. For moderate global wanning, resulting in ocean temperature increases of a few °C, the large- increase in basal melting can become the dominant factor in the long-term response of the ice sheet. The results from ice-sheet modelling show that the increased basal melt rates lead to a reduction of the ice shelves, increased strain rates and flow at the grounding lines, then thinning and floating of the marine ice sheets, with consequential further basal melting. The mass loss from basal melting is counteracted to some extent by the increased accumulation, but in the long term the area of ice cover decreases, particularly in West Antarctica, and the mass loss can dominate. The ice-sheet ice-shelf model of Budd and others (1994) with 20 km resolution has been modified and used to carry out a number of sensitivity studies of the long-term response of the ice sheet to prescribed amounts of global warming. The changes in the ice sheet are computed out to near-equilibrium, but most of the changes take place with in the first lew thousand years. For a global mean temperature increase of 3°C with an ice-shelf basal melt rate of 5 m a−1 the ice shelves disappear with in the first few hundred years, and the marine-based parts of the ice sheet thin and retreat. By 2000 years the West Antarctic region is reduced to a number of small, isolated ice caps based on the bedrock regions which are near or above sea level. This allows the warmer surface ocean water to circulate through the archipelago in summer, causing a large change to the local climate of the region.

scholarly journals Long-term load forecast modelling using a fuzzy logic approach

2016 ◽  
Vol 18 (2) ◽  
pp. 123-127 ◽  
Author(s):  
Danladi Ali ◽  
Michael Yohanna ◽  
M.I. Puwu ◽  
B.M. Garkida
Keyword(s):  
Fuzzy Logic ◽  
Load Forecast ◽  
Fuzzy Logic Approach ◽  
Logic Approach

scholarly journals Neumayer III and Kohnen Station in Antarctica operated by the Alfred Wegener Institute

2016 ◽  
Vol 2 ◽  
Author(s):  
Christine Wesche ◽  
Rolf Weller ◽  
Gert König-Langlo ◽  
Tanja Fromm ◽  
Alfons Eckstaller ◽  
...  
Keyword(s):  
Ice Core ◽  
Ice Shelf ◽  
Deep Drilling ◽  
Research Activities ◽  
Starting Point ◽  
Air Chemistry ◽  
Dronning Maud Land ◽  
Core Project ◽  
The Antarctic

The Alfred Wegener Institute operates two stations in Dronning Maud Land, Antarctica. The German overwintering station Neumayer III is located on the Ekström Ice Shelf at 70°40’S and 08°16’W and is the logistics base for three long-term observatories (meteorology, air chemistry and geophysics) and nearby research activities. Due to the vicinity to the coast (ca. 20 km from the ice shelf edge), the Neumayer III Station is the junction for many German Antarctic expeditions, especially as the starting point for the supply traverse for the second German station Kohnen.The summer station Kohnen is located about 600 km from the coast and 750 km from Neumayer III Station on the Antarctic plateau at 75°S and 00°04’E. It was erected as the base for the deep-drilling ice core project, which took place between 2001 and 2006. Since then Kohnen Station is used as a logistics base for different research projects.

scholarly journals Multidecadal warming of Antarctic waters

Science ◽  
2014 ◽  
Vol 346 (6214) ◽  
pp. 1227-1231 ◽  
Author(s):  
Sunke Schmidtko ◽  
Karen J. Heywood ◽  
Andrew F. Thompson ◽  
Shigeru Aoki
Keyword(s):  
Continental Shelf ◽  
Large Scale ◽  
Bottom Water ◽  
Heat Content ◽  
Ice Shelf ◽  
Antarctic Continental Shelf ◽  
Antarctic Waters ◽  
Core Depth ◽  
The Antarctic

Decadal trends in the properties of seawater adjacent to Antarctica are poorly known, and the mechanisms responsible for such changes are uncertain. Antarctic ice sheet mass loss is largely driven by ice shelf basal melt, which is influenced by ocean-ice interactions and has been correlated with Antarctic Continental Shelf Bottom Water (ASBW) temperature. We document the spatial distribution of long-term large-scale trends in temperature, salinity, and core depth over the Antarctic continental shelf and slope. Warming at the seabed in the Bellingshausen and Amundsen seas is linked to increased heat content and to a shoaling of the mid-depth temperature maximum over the continental slope, allowing warmer, saltier water greater access to the shelf in recent years. Regions of ASBW warming are those exhibiting increased ice shelf melt.

scholarly journals On the Use of Satellite Observations to Fill Gaps in the Halley Station Total Ozone Record

2021 ◽  
Author(s):  
Lily Zhang ◽  
Susan Solomon ◽  
Kane Stone ◽  
John Burrows ◽  
Steve Colwell ◽  
...  
Keyword(s):  
Total Ozone ◽  
Research Station ◽  
Ice Shelf ◽  
Total Column Ozone ◽  
Significant Difference ◽  
Antarctic Ozone ◽  
Historic Record ◽  
Column Ozone ◽  
The Antarctic

<p>Measurements by the Dobson ozone spectrophotometer at the British Antarctic Survey’s (BAS) Halley research station form a record of Antarctic total column ozone that dates back to 1956. Due to its location, length, and completeness, the record has been, and continues to be, uniquely important for studies of long-term changes in Antarctic ozone. However, a crack in the ice shelf on which it resides forced the station to abruptly close for eight months and [SC-UB1]  led to a gap in its historic record.  We develop and test a method for filling in the record of Halley total ozone by combining and bias-correcting overpass data from a range of different satellite instruments. Tests suggest that our method reproduces the monthly ground-based Dobson total ozone values to within 20 Dobson units.  We show that our approach improves on the overall performance as compared to simply using the raw satellite average or an individual instrument. The method also provides a check on the consistency of the automated Dobson used at Halley after 2018 compared to earlier manual Dobson data, and suggests a significant difference between the two.  The filled Halley dataset provides further support that the Antarctic ozone hole is healing not only during September, but also in January.</p>

An assessment of basal melting parameterisations for Antarctic ice shelves

2021 ◽  
Author(s):  
Clara Burgard ◽  
Nicolas Jourdain
Keyword(s):  
Climate Model ◽  
Ice Sheet ◽  
Coupled Model ◽  
Ice Shelf ◽  
Antarctic Ice Sheet ◽  
Ice Shelves ◽  
Global Sea Level ◽  
Basal Melting ◽  
The Antarctic

<p>Ocean-induced melting at the base of ice shelves is one of the main drivers of the currently observed mass loss of the Antarctic Ice Sheet. A good understanding of the interaction between ice and ocean at the base of the ice shelves is therefore crucial to understand and project the Antarctic contribution to global sea-level rise. </p><p>Due to the high difficulty to monitor these regions, our understanding of the processes at work beneath ice shelves is limited. Still, several parameterisations of varying complexity have been developed in past decades to describe the ocean-induced sub-shelf melting. These parameterisations can be implemented into standalone ice-sheet models, for example when conducting long-term projections forced with climate model output.</p><p>An assessment of the performance of these parameterisations was conducted in an idealised setup (Favier et al, 2019). However, the application of the better-performing parameterisations in a more realistic setup (e.g. Jourdain et al., 2020) has shown that individual adjustments and corrections are needed for each ice shelf.</p><p>In this study, we revisit the assessment of the parameterisations, this time in a more realistic setup than previous studies. To do so, we apply the different parameterisations on several ice shelves around Antarctica and compare the resulting melt rates to satellite and oceanographic estimates. Based on this comparison, we will refine the parameters and propose an approach to reduce uncertainties in long-term sub-shelf melting projections.</p><p><em>References</em><br><em>- Favier, L., Jourdain, N. C., Jenkins, A., Merino, N., Durand, G., Gagliardini, O., Gillet-Chaulet, F., and Mathiot, P.: Assessment of sub-shelf melting parameterisations using the ocean–ice-sheet coupled model NEMO(v3.6)–Elmer/Ice(v8.3) , Geosci. Model Dev., 12, 2255–2283, https://doi.org/10.5194/gmd-12-2255-2019, 2019. </em><br><em>- Jourdain, N. C., Asay-Davis, X., Hattermann, T., Straneo, F., Seroussi, H., Little, C. M., and Nowicki, S.: A protocol for calculating basal melt rates in the ISMIP6 Antarctic ice sheet projections, The Cryosphere, 14, 3111–3134, https://doi.org/10.5194/tc-14-3111-2020, 2020. </em></p>

Long term electricity consumption forecast in Brazil: A fuzzy logic approach

2016 ◽  
Vol 54 ◽  
pp. 18-27 ◽  
Author(s):  
Fabiano Castro Torrini ◽  
Reinaldo Castro Souza ◽  
Fernando Luiz Cyrino Oliveira ◽  
Jose Francisco Moreira Pessanha
Keyword(s):  
Fuzzy Logic ◽  
Electricity Consumption ◽  
Fuzzy Logic Approach ◽  
Logic Approach

scholarly journals Remote Sensing of Antarctic Glacier and Ice-Shelf Front Dynamics—A Review

2018 ◽  
Vol 10 (9) ◽  
pp. 1445 ◽  
Author(s):  
Celia Baumhoer ◽  
Andreas Dietz ◽  
Stefan Dech ◽  
Claudia Kuenzer
Keyword(s):  
Remote Sensing ◽  
Antarctic Peninsula ◽  
Ice Sheet ◽  
Ice Shelf ◽  
Clear Trend ◽  
Antarctic Ice Sheet ◽  
Victoria Land ◽  
The Antarctic ◽  
Front Dynamics

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.

The Quaternary in Southeast Asia

2005 ◽  
Author(s):  
Geoffrey Hope
Keyword(s):  
Ice Age ◽  
Global Changes ◽  
Ice Shelf ◽  
Quaternary Period ◽  
Ice Caps ◽  
Ice Volume ◽  
Ice Cap ◽  
The Antarctic ◽  
Rapid Environmental Change

We live in the Quaternary period and are a product of its wide fluctuations in climate and rapid environmental change. From at least the Mid-Miocene, about 25 million years ago, the expansion of the Southern Ocean has supported a powerful westerly wind system. These winds prevent tropical heat from reaching the Antarctic region, which in turn has allowed the gradual refrigeration of the world’s oceans as ice built up on Antarctica (and eventually formed an ice shelf over the sea; Nunn 1999). Earlier in the Tertiary, when the ocean column was warm from top to bottom, seasonal cooling was offset by rising warm water, and the ocean currents effectively transported heat to the poles. For the last 2 million years the main mass of the oceans has remained at maximum density, around 4°C, with warmer surface waters of the tropical and temperate regions floating only in the upper few hundred metres above the thermocline. The Quaternary is the period of refrigerated ocean which marks an ice age, with the Earth in such a delicate thermal equilibrium that relatively minor changes in the amount of solar radiation received by a given hemisphere in a given season cause major fluctuations of ice volume in terrestrial ice caps. The marked asymmetry of land and sea in the two hemispheres means that the effects of changes in the season of closest approach to the sun, of the degree of tilt of the planet and the eccentricity of the orbit, cause instability in the long-term climate. The Quaternary is defined by successive expansions and retreats of ice caps, with the maximum episodes of ice and of warmth (the interstadials) each lasting around 10 000 years. Intermediate times are cooler than present, and these persist for around 100 000 years. The lock-up of ice is reflected by global changes in sea level, ocean levels falling about 125 m during glacial maxima and rising up to 6 m above present during some interglacials. The Antarctic ice cap retains about 75 m of the ocean’s water even during the interglacial phases.

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