The changing extent of the glaciers along the western Ross Sea, Antarctica

Fountain, Andrew G.; Glenn, Bryce; Scambos, Ted

doi:10.1130/g39240.1

Cited by 11 publications

(24 citation statements)

References 24 publications

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“…The DN values are multiples of the TOA values (the TOA values are from −1 to 1, and the DN values for Landsat TM are from 0 to 255), which makes σ c bigger, thereby increasing ∆h color and f, based on Formulas 7and (8). Two different objects could only be merged when f is less than the segmentation scale.…”

Section: Global Extraction Based On Objectsmentioning

confidence: 99%

“…Furthermore, surface snow is one of the most important water resources of most rivers in high-mountain regions. It is not only the direct cause of spring flooding due to melting but also plays an important role in managing local water resources, preventing disasters, and forecasting and simulating snowmelt [8]. Due to global warming and corresponding glacier recession, ice/snow-covered areas in mountainous regions have decreased rapidly in recent decades.…”

Section: Introductionmentioning

confidence: 99%

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An Automated Method for Surface Ice/Snow Mapping Based on Objects and Pixels from Landsat Imagery in a Mountainous Region

et al. 2020

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Surface ice/snow is a vital resource and is sensitive to climate change in many parts of the world. The accurate and timely measurement of the spatial distribution of ice/snow is critical for managing water resources. Object-oriented and pixel-oriented methods often have some limitations due to the image segmentation scale, the determination of the optimal threshold and background heterogeneity. Therefore, this study proposes a method for automatically extracting large-scale surface ice/snow from Landsat series images, which takes advantage of the combination of image segmentation, the watershed algorithm and a series of ice/snow indices. We tested our novel method in three different regions in the Karakoram Mountains, and the experimental results show that the produced ice/snow map obtained a user’s accuracy greater than 90%, a producer’s accuracy greater than 97%, an overall accuracy greater than 98% and a kappa coefficient greater than 0.93. Comparing the extraction results under segmentation scales of 10, 15, 20 and 25, the user’s accuracy and producer’s accuracy from the proposed method are very similar, which indicates that the proposed method is more reliable and stable for extracting ice/snow objects than the object-oriented method. Due to the different reflectivity values in the near-infrared band in the snow and water categories, the normalized difference forest snow index (NDFSI) is suitable for Landsat TM and ETM+ images. This study can serve as a reliable, scientific reference for rapidly and accurately extracting ice/snow objects.

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Section: Global Extraction Based On Objectsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

An Automated Method for Surface Ice/Snow Mapping Based on Objects and Pixels from Landsat Imagery in a Mountainous Region

et al. 2020

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“…Measuring outlet glacier and ice shelf dynamics by tracking terminus positions is a commonly accepted approach [15,22,28,53]. A wide range of methods for glacier change monitoring is available [80].…”

Section: Methods To Measure Calving Front Dynamicsmentioning

confidence: 99%

“…For Antarctica, the processes controlling the calving of marine-terminating glaciers and ice shelves are only partly known [17,18]. Existing studies have either analyzed fronts of (i) individual glacial features with very high spatial and temporal resolution [19][20][21], (ii) larger regions of the Antarctic coastline at a lower temporal resolution [22][23][24], or (iii) the entire Antarctic coastline for single years based on entire satellite imagery mosaics [25][26][27].…”

Section: Introduction: Relevance Of Antarctica and Scope Of This Reviewmentioning

confidence: 99%

“…Depending on the study design (region of interest, observation timespan, interval of observation, spatial coverage), the reasons for retreating and advancing fronts are attributed to different drivers [22,24,[28][29][30]. However, no review paper exists that allows a comprehensive overview on available ice shelf and glacier front positions along the Antarctic coastline.…”

Section: Introduction: Relevance Of Antarctica and Scope Of This Reviewmentioning

confidence: 99%

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

et al. 2018

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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.

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Response of Marine‐Terminating Glaciers to Forcing: Time Scales, Sensitivities, Instabilities, and Stochastic Dynamics

2018

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Recent observations indicate that many marine-terminating glaciers in Greenland and Antarctica are currently retreating and thinning, potentially due to long-term trends in climate forcing. In this study, we describe a simple two-stage model that accurately emulates the response to external forcing of marine-terminating glaciers simulated in a spatially extended model. The simplicity of the model permits derivation of analytical expressions describing the marine-terminating glacier response to forcing. We find that there are two time scales that characterize the stable glacier response to external forcing, a fast time scale of decades to centuries, and a slow time scale of millennia. These two time scales become unstable at different thresholds of bed slope, indicating that there are distinct slow and fast forms of the marine ice sheet instability. We derive simple expressions for the approximate magnitude and transient evolution of the stable glacier response to external forcing, which depend on the equilibrium glacier state and the strength of nonlinearity in forcing processes. The slow response rate of marine-terminating glaciers indicates that current changes at some glaciers are set to continue and accelerate in coming centuries in response to past climate forcing and that the current extent of change at these glaciers is likely a small fraction of the future committed change caused by past climate forcing. Finally, we find that changing the amplitude of natural fluctuations in some nonlinear forcing processes, such as ice shelf calving, changes the equilibrium glacier state. Plain Language SummaryWe develop a very simple mathematical model to explain how change in climate causes change in marine glaciers. The model shows that this response mostly occurs in two phases, a fast phase over tens to hundreds of years, and a slow phase over thousands of years. Glaciers have a larger response when they are on flat bedrock or when changes in the length of their ice shelf occur due to iceberg detachment. Even though some glaciers have not thinned or retreated significantly in recent years because they sit on steep downward sloping bedrock, they may experience rapid thinning and retreat in the future as they continue to respond to past climate change over thousands of years. Noise in climate and other processes that cause glaciers to be noisy can potentially cause permanent changes in glacier size.These results indicate that we should include noise when making predictions of glaciers changes so that we can calculate uncertainty in future projections and the impact of noise on permanent glacier size.It has long been understood that glaciers act as integrators of external forcing (Nye, 1960(Nye, , 1963a(Nye, , 1963b(Nye, , 1965. Stochastic noise in climate forcing is integrated by glaciers on a characteristic time scale set by glacier

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The changing extent of the glaciers along the western Ross Sea, Antarctica

Cited by 11 publications

References 24 publications

An Automated Method for Surface Ice/Snow Mapping Based on Objects and Pixels from Landsat Imagery in a Mountainous Region

An Automated Method for Surface Ice/Snow Mapping Based on Objects and Pixels from Landsat Imagery in a Mountainous Region

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

Response of Marine‐Terminating Glaciers to Forcing: Time Scales, Sensitivities, Instabilities, and Stochastic Dynamics

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