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Author: Whyjay Zheng Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Glacier thinning and retreat have accelerated globally in the last century and are the largest contributor to rising sea levels. For the Arctic region, observations and modeling results have shown that extensive warming is taking place. However, the recent glacier dynamics (mass balance and ice discharge) in many Arctic regions have not been well studied due to the remote nature of these glaciers.This thesis uses multiple types of satellite data to quantify the mass balance and ice discharge for three Arctic regions showing dramatic glacier change in recent decades possibly due to Arctic warming. The objective is to resolve the mass budget and velocity pattern on a per glacier basis and understand the mechanisms driving recent changes. To facilitate the entire workflow, our research team has developed the Cryosphere and Remote Sensing Toolkit (CARST) software, and I am the lead author. CARST provides useful python and bash scripts that use satellite imagery, particularly SAR and optical images, to monitor changes of glaciers and ice caps through time. The first study area is Franz Josef Land (FJL), Russia, which is currently subjected to a rapidly-warming climate in the Arctic. I combine surface elevation data derived from different sources and times, including the WorldView satellite series and the ArcticDEM data set (2011-2015), SPOT-5 (2007), CryoSat-2 (2011-2015), and a digitized cartographic map (1953). I calculate elevation change rate (dh/dt) in two different periods, and the results show a two-fold rate of ice loss over the past 60 years, from _2.18 ± 0.72 Gt/yr (1953-2011/2015 average) to _4.43 ± 0.78 Gt/yr (2011-2015). Despite being spatially variable, a trend of increased thinning from NE towards SW is discovered, suggesting a link to the local gradient in temperature and precipitation. Ice loss is mostly focused on marine-terminating glaciers probably due to the interaction between glaciers and warming ocean water. These retreating glaciers generated a new island in 2016 and more islands are likely to emerge in the foreseeable future as FJL's ice loss has reached an unprecedented rate. The research focus in the following chapter shifts to the neighboring archipelago called Severnaya Zemlya, Russia. A surge-like collapse initiated in 2013 in Vavilov Ice Cap, one of many ice caps in this region. By spring 2019, this ice cap had lost 9.5 Gt of ice. Using time series of surface elevation and glacier velocity derived from multiple satellite data sets such as WorldView (elevation), ArcticDEM (elevation), ASTER (elevation), Landsat 8 (velocity), Sentinel-1, (velocity), Sentinel-2 (velocity), Radarsat-2 (velocity), and ALOS-2 (velocity), I identify a shift of flow pattern starting in 2017 when shear margins formed within the grounded marine piedmont fan. Multiple summer speedups occurred after the new flow pattern formed, possibly with the aid of basal lubrication due to surface melt. With the analysis using multiple physical models, it is suggested that the collapsed ice cap has entered a new ice stream-like regime in which diffusion of surface thinning controls the glacier dynamics. This is the first documented case of an ice stream-like feature ever being formed, and this glacier now flows at a higher speed and drains the ice cap more efficiently. To publicize the findings and their scientific implications, I made two videos showing the temporal changes of the terminus position and speed pattern, which are available on Youtube. In the last chapter, I further develop a physical framework for the glacier perturbation model to understand how different glaciers respond to basal lubrication. The modified 1-D flowline model suggests two physical quantities, Péclet number (Pe) and a value dubbed J0, governing glacier vulnerability to basal lubrication. To test the model, I use the Ice Thickness Models Intercomparison eXperiment (ITMIX) data set and the NASA MEaSUREs ITS_LIVE data set. ITMIX contains velocity, elevation, and ice thickness data from Austfonna Ice Cap, Svalbard, where multiple glacier collapse events occurred within the past 10 years. I calculate Pe and |J0| using data from the ITMIX and compare them with the speed change revealed by the ITS_LIVE data set. The results show that a low Pe and a high |J0| correspond to the high magnitude of glacier speedup during 1995-2018, as suggested by the model prediction. My analysis implies that basal lubrication can lead to a prolonged or even permanent change of glacier dynamics for some glaciers. These "weak" glaciers might be able to waste ice more rapidly than we thought, posing a warning of an underestimated sea level rise projection.
Author: Whyjay Zheng Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Glacier thinning and retreat have accelerated globally in the last century and are the largest contributor to rising sea levels. For the Arctic region, observations and modeling results have shown that extensive warming is taking place. However, the recent glacier dynamics (mass balance and ice discharge) in many Arctic regions have not been well studied due to the remote nature of these glaciers.This thesis uses multiple types of satellite data to quantify the mass balance and ice discharge for three Arctic regions showing dramatic glacier change in recent decades possibly due to Arctic warming. The objective is to resolve the mass budget and velocity pattern on a per glacier basis and understand the mechanisms driving recent changes. To facilitate the entire workflow, our research team has developed the Cryosphere and Remote Sensing Toolkit (CARST) software, and I am the lead author. CARST provides useful python and bash scripts that use satellite imagery, particularly SAR and optical images, to monitor changes of glaciers and ice caps through time. The first study area is Franz Josef Land (FJL), Russia, which is currently subjected to a rapidly-warming climate in the Arctic. I combine surface elevation data derived from different sources and times, including the WorldView satellite series and the ArcticDEM data set (2011-2015), SPOT-5 (2007), CryoSat-2 (2011-2015), and a digitized cartographic map (1953). I calculate elevation change rate (dh/dt) in two different periods, and the results show a two-fold rate of ice loss over the past 60 years, from _2.18 ± 0.72 Gt/yr (1953-2011/2015 average) to _4.43 ± 0.78 Gt/yr (2011-2015). Despite being spatially variable, a trend of increased thinning from NE towards SW is discovered, suggesting a link to the local gradient in temperature and precipitation. Ice loss is mostly focused on marine-terminating glaciers probably due to the interaction between glaciers and warming ocean water. These retreating glaciers generated a new island in 2016 and more islands are likely to emerge in the foreseeable future as FJL's ice loss has reached an unprecedented rate. The research focus in the following chapter shifts to the neighboring archipelago called Severnaya Zemlya, Russia. A surge-like collapse initiated in 2013 in Vavilov Ice Cap, one of many ice caps in this region. By spring 2019, this ice cap had lost 9.5 Gt of ice. Using time series of surface elevation and glacier velocity derived from multiple satellite data sets such as WorldView (elevation), ArcticDEM (elevation), ASTER (elevation), Landsat 8 (velocity), Sentinel-1, (velocity), Sentinel-2 (velocity), Radarsat-2 (velocity), and ALOS-2 (velocity), I identify a shift of flow pattern starting in 2017 when shear margins formed within the grounded marine piedmont fan. Multiple summer speedups occurred after the new flow pattern formed, possibly with the aid of basal lubrication due to surface melt. With the analysis using multiple physical models, it is suggested that the collapsed ice cap has entered a new ice stream-like regime in which diffusion of surface thinning controls the glacier dynamics. This is the first documented case of an ice stream-like feature ever being formed, and this glacier now flows at a higher speed and drains the ice cap more efficiently. To publicize the findings and their scientific implications, I made two videos showing the temporal changes of the terminus position and speed pattern, which are available on Youtube. In the last chapter, I further develop a physical framework for the glacier perturbation model to understand how different glaciers respond to basal lubrication. The modified 1-D flowline model suggests two physical quantities, Péclet number (Pe) and a value dubbed J0, governing glacier vulnerability to basal lubrication. To test the model, I use the Ice Thickness Models Intercomparison eXperiment (ITMIX) data set and the NASA MEaSUREs ITS_LIVE data set. ITMIX contains velocity, elevation, and ice thickness data from Austfonna Ice Cap, Svalbard, where multiple glacier collapse events occurred within the past 10 years. I calculate Pe and |J0| using data from the ITMIX and compare them with the speed change revealed by the ITS_LIVE data set. The results show that a low Pe and a high |J0| correspond to the high magnitude of glacier speedup during 1995-2018, as suggested by the model prediction. My analysis implies that basal lubrication can lead to a prolonged or even permanent change of glacier dynamics for some glaciers. These "weak" glaciers might be able to waste ice more rapidly than we thought, posing a warning of an underestimated sea level rise projection.
Author: Manish Pandey Publisher: John Wiley & Sons ISBN: 1119787726 Category : Technology & Engineering Languages : en Pages : 485
Book Description
ADVANCES IN REMOTE SENSING TECHNOLOGY AND THE THREE POLES Covers recent advances in remote sensing technology applied to the “Three Poles”, a concept encompassing the Arctic, Antarctica, and the Himalayas Advances in Remote Sensing Technology and the Three Poles is a multidisciplinary approach studying the lithosphere, hydrosphere (encompassing both limnosphere, and oceanosphere), atmosphere, biosphere, and anthroposphere, of the Arctic, the Antarctic and the Himalayas. The drastic effects of climate change on polar environments bring to the fore the often subtle links between climate change and processes in the hydrosphere, biosphere, and lithosphere, while unanswered questions of the polar regions will help plan and formulate future research projects. Sample topics covered in the work include: Terrestrial net primary production of the Arctic and modeling of Arctic landform evolution Glaciers and glacial environments, including a geological, geophysical, and geospatial survey of Himalayan glaciers Sea ice dynamics in the Antarctic region under a changing climate, the Quaternary geology and geomorphology of Antarctica Continuous satellite missions, data availability, and the nature of future satellite missions, including scientific data sharing policies in different countries Software, tools, models, and remote sensing technology for investigating polar and other environments For postgraduates and researchers working in remote sensing, photogrammetry, and landscape evolution modeling, Advances in Remote Sensing Technology and the Three Poles is a crucial resource for understanding current technological capabilities in the field along with the latest scientific research that has been conducted in polar areas.
Author: Tyler Clark Sutterley Publisher: ISBN: 9781339784113 Category : Languages : en Pages : 132
Book Description
The Earth's great ice sheets are losing mass at accelerating levels, rising global sea levels and posing a significant problem to society. The ice sheets contain enough water to raise sea level by 65 meters, and are the largest reservoirs of freshwater on the planet. Measurements of current ice sheet mass change are important in order to assess their current contribution to sea level rise, and to constrain future projections. There are three general approaches for measuring the current mass balance of ice sheets: the gravimetric method using time-variable gravity measurements, the altimetric method combining surface elevation change measurements with estimates of the density change, and the mass budget method combining rates of mass input from snow and rain with rates of mass output from meltwater runoff, ice discharge and other processes. In this dissertation, we use multiple independent measurements to assess the current uncertainties in mass balance efforts, and to create new estimates of current ice sheet mass change. We investigate key regions of Antarctica, where changes in the ice sheet velocity structure have led to accelerating mass losses. We compile new assessments of the mass change of the Greenland ice sheet, where increased rates of surface runoff and losses from ice sheet dynamics have dramatically shifted the mass balance regime. The work helps constrain estimation errors from GRACE, provides new constraints to ice sheet and glacial isostatic adjustment models, and helps improve our general understanding of the mechanisms driving current ice sheet mass change.
Author: Jeffrey S. Kargel Publisher: Springer ISBN: 3540798188 Category : Technology & Engineering Languages : en Pages : 936
Book Description
An international team of over 150 experts provide up-to-date satellite imaging and quantitative analysis of the state and dynamics of the glaciers around the world, and they provide an in-depth review of analysis methodologies. Includes an e-published supplement. Global Land Ice Measurements from Space - Satellite Multispectral Imaging of Glaciers (GLIMS book for short) is the leading state-of-the-art technical and interpretive presentation of satellite image data and analysis of the changing state of the world's glaciers. The book is the most definitive, comprehensive product of a global glacier remote sensing consortium, Global Land Ice Measurements from Space (GLIMS, http://www.glims.org). With 33 chapters and a companion e-supplement, the world's foremost experts in satellite image analysis of glaciers analyze the current state and recent and possible future changes of glaciers across the globe and interpret these findings for policy planners. Climate change is with us for some time to come, and its impacts are being felt by the world's population. The GLIMS Book, to be released about the same time as the IPCC's 5th Assessment report on global climate warming, buttresses and adds rich details and authority to the global change community's understanding of climate change impacts on the cryosphere. This will be a definitive and technically complete reference for experts and students examining the responses of glaciers to climate change. World experts demonstrate that glaciers are changing in response to the ongoing climatic upheaval in addition to other factors that pertain to the circumstances of individual glaciers. The global mosaic of glacier changes is documented by quantitative analyses and are placed into a perspective of causative factors. Starting with a Foreword, Preface, and Introduction, the GLIMS book gives the rationale for and history of glacier monitoring and satellite data analysis. It includes a comprehensive set of six "how-to" methodology chapters, twenty-five chapters detailing regional glacier state and dynamical changes, and an in-depth summary and interpretation chapter placing the observed glacier changes into a global context of the coupled atmosphere-land-ocean system. An accompanying e-supplement will include oversize imagery and other other highly visual renderings of scientific data.
Author: Robert Massom Publisher: Springer Science & Business Media ISBN: 3540305653 Category : Science Languages : en Pages : 511
Book Description
Polar Remote Sensing is a two-volume work providing a comprehensive, multidisciplinary discussion of the applications of satellite sensing. Volume 2 focuses on the ice sheets, icebergs, and interactions between ice sheets and the atmosphere and ocean. It contains information about the applications of satellite remote sensing in all relevant polar related disciplines, including glaciology, meteorology, climate and radiation balance and oceanogaraphy. It also provides a brief review of the state-of-the-art of each discipline, including current issues and questions. Various passive and active remote sensor types are discussed, and the book then concentrates on specific geophysical applications. Its interdisciplinary approach means that major advances and publications are highlighted. Polar Remote Sensing: Ice Sheets summarizes fundamental principles of detectors, imaging and geophysical product retrieval includes a chapter on the important new field of satellite synthetic-aperture radar interferometry is a "one stop shop" for polar remote sensing information contains significant new information on the Earth's polar regions describes sophisticated groundbased remote sensing applications with specific reference to their use in polar regions.
Author: Jonathan L. Bamber Publisher: Cambridge University Press ISBN: 9780521808958 Category : Science Languages : en Pages : 672
Book Description
A detailed and comprehensive overview of observational and modelling techniques for all climate change, environmental science and glaciology researchers.
Author: Andrew K. Melkonian Publisher: ISBN: Category : Languages : en Pages : 624
Book Description
Glaciers outside the icesheets currently supply roughly the same amount of water to sea level rise (SLR) as Antarctica and Greenland and will likely constitute a significant fraction of SLR through 2100. SLR is one of the biggest challenges facing humanity, and much uncertainty remains regarding the contribution of glacier mass loss to SLR. Here we examine glaciers in the Patagonia region of southern Chile/Argentina, the Russian High Arctic (RHA) and Alaska, which have all contributed disproportionately to SLR, a trend that is expected to continue through 2100. The RHA is projected to be among the largest contributors, with total mass loss exceeding Alaska for 2006-2100 despite its smaller ice volume. We focus on several icefields, including two that have received relatively little attention, the Cordillera Darwin Icefield (CDI, 69.6? W, 54.6? S, 2,600 km2 of glaciated area) in the Patagonia region of southern Chile, and the Novaya Zemlya Icefield (NovZ, 65? W, 76? N, 22,100 km2 of glaciated area) in the Russian High Arctic. We also examine the Juneau Icefield (JIF, 58.3? N to 59.7? N, 3,830 km2) and Stikine Icefield (56.75? N to 58.5? N, 5,800 km2) in southeast Alaska. We produce high-resolution maps of surface elevation change rates (dh) and dt velocities for these icefields. dh dt are calculated by applying a weighted lin- ear regression to horizontally- and vertically-aligned digital elevation models (DEMs), revealing thinning patterns for individual glacier basins and allowing us to estimate total mass loss for each icefield. To our knowledge, the work presented here includes the first published study to use the technique of DEM time series to study mass loss of entire icefields. Velocities are measured by pixel-tracking applied to satellite image pairs, helping constrain the dynamic component of mass loss and detect acceleration. We provide a brief overview of the impact of changing various pixel-tracking parameters on velocity measurements, demonstrating, for example, how the ability to adjust parameters helps maximize coverage compared to working with fixed parameter values. We find an average mass loss rate at the CDI of -3.9"1.5 Gt yr-1 between 2000 and 2011, the first produced for this icefield. Three marine-terminating glaciers that cover 12% of the icefield area account for 31% of mass loss. Velocity measurements at the largest of these, the rapidly retreating Marinelli Glacier, constrain the lower bound on the annual calving flux as approximately 82"41% of the average mass loss rate for the glacier. The disproportionate mass loss contribution of the three tidewater glaciers, coupled with the high calving flux and retreat at Marinelli Glacier, provide evidence that dynamic mass loss is an important component of thinning at the CDI. At NovZ, we extend estimates of mass loss back to 1952 and up to the present. We find that the recent average thinning rate of -0.41"0.10 m water equivalent yr-1 (m w.e. yr-1, or elevation change at density of 1000 kg m-3) from 2012-2013/2014 is higher than the long-term average of -0.24"0.04 m w.e. yr-1 from 1952-2013/2014. Some of the increase is likely due to warming in the region, as recent thinning is higher than the long-term average at both land- and marine-terminating glaciers. There is also evidence of a dynamic component, because recent thinning, retreat and front velocities are all substantially greater at tidewater-terminating glaciers than land-terminating glaciers. The impact of ice dynamics is particularly apparent at Inostrantseva Glacier (INO), which ac- celerated at some point after 2006, leading to rapid retreat and thinning there. We compare our results at the CDI and NovZ with our dh dt and velocities for the JIF and Stikine in southeast Alaska. We explore how variations in climate, hypsometry and dynamics all contribute to the different magnitudes and patterns of mass loss at each icefield. The methods presented here for the assessment of icefield mass loss will help better constrain their contributions to SLR over the coming century.
Author: Simon Haykin Publisher: John Wiley & Sons ISBN: 9780471554943 Category : Technology & Engineering Languages : en Pages : 724
Book Description
Describes the latest remote sensing technologies used to detect ice hazards in the marine environment; map surface currents, sea-state and surface winds; study ice dynamics, over ice transportation, oil spill countermeasures, climate changes and ice reconnaisance. Includes such technologies as acoustic sensing, ice-thickness measurement, passive microwave remote sensing, ground wave and surface-based radars.
Author: Intergovernmental Panel on Climate Change (IPCC) Publisher: Cambridge University Press ISBN: 9781009157971 Category : Science Languages : en Pages : 755
Book Description
The Intergovernmental Panel on Climate Change (IPCC) is the leading international body for assessing the science related to climate change. It provides policymakers with regular assessments of the scientific basis of human-induced climate change, its impacts and future risks, and options for adaptation and mitigation. This IPCC Special Report on the Ocean and Cryosphere in a Changing Climate is the most comprehensive and up-to-date assessment of the observed and projected changes to the ocean and cryosphere and their associated impacts and risks, with a focus on resilience, risk management response options, and adaptation measures, considering both their potential and limitations. It brings together knowledge on physical and biogeochemical changes, the interplay with ecosystem changes, and the implications for human communities. It serves policymakers, decision makers, stakeholders, and all interested parties with unbiased, up-to-date, policy-relevant information. This title is also available as Open Access on Cambridge Core.
Author: Vivien Gornitz Publisher: Columbia University Press ISBN: 0231548893 Category : Science Languages : en Pages : 364
Book Description
The Arctic is thawing. In summer, cruise ships sail through the once ice-clogged Northwest Passage, lakes form on top of the Greenland Ice Sheet, and polar bears swim farther and farther in search of waning ice floes. At the opposite end of the world, floating Antarctic ice shelves are shrinking. Mountain glaciers are in retreat worldwide, unleashing flash floods and avalanches. We are on thin ice—and with melting permafrost’s potential to let loose still more greenhouse gases, these changes may be just the beginning. Vanishing Ice is a powerful depiction of the dramatic transformation of the cryosphere—the world of ice and snow—and its consequences for the human world. Delving into the major components of the cryosphere, including ice sheets, valley glaciers, permafrost, and floating ice, Vivien Gornitz gives an up-to-date explanation of key current trends in the decline of ice mass. Drawing on a long-term perspective gained by examining changes in the cryosphere and corresponding variations in sea level over millions of years, she demonstrates the link between thawing ice and sea-level rise to point to the social and economic challenges on the horizon. Gornitz highlights the widespread repercussions of ice loss, which will affect countless people far removed from frozen regions, to explain why the big meltdown matters to us all. Written for all readers and students interested in the science of our changing climate, Vanishing Ice is an accessible and lucid warning of the coming thaw.
Author: Whyjay Zheng
Author: Whyjay Zheng
Author: Manish Pandey
Author: Tyler Clark Sutterley
Author: Jeffrey S. Kargel
Author: Robert Massom
Author: Jonathan L. Bamber
Author: Andrew K. Melkonian
Author: Simon Haykin
Author: Intergovernmental Panel on Climate Change (IPCC)
Author: Vivien Gornitz