Melt Water Retention Processes In Snow And Firn On Ice Sheets And Glaciers Observations And Modeling
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Melt Water Retention Processes In Snow And Firn On Ice Sheets And Glaciers Observations And Modeling
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Author : W. Tad Pfeffer
language : en
Publisher: Frontiers Media SA
Release Date : 2018-11-08
Melt Water Retention Processes In Snow And Firn On Ice Sheets And Glaciers Observations And Modeling written by W. Tad Pfeffer and has been published by Frontiers Media SA this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-11-08 with categories.
Melt takes place where the surface of glaciers or ice sheets interacts with the atmosphere. While the processes governing surface melt are fairly well understood, the pathways of the meltwater, from its origin to the moment it leaves a glacier system, remain enigmatic. It is not even guaranteed that meltwater leaves a glacier or ice sheet. On Greenland, for example, only slightly more than 50% of the meltwater runs off. The remainder mostly refreezes within the so-called firn cover of the ice sheet. This eBook contains 11 studies which tackle the challenge of understanding meltwater retention in snow and firn from various angles. The studies focus both on mountain glaciers and on the Greenland ice sheet and address challenges such as measuring firn properties, quantifying their influence on meltwater retention, modelling firn processes and meltwater refreezing as well as unravelling the mechanisms within the recently discovered Greenland firn aquifers.
Arctic Hydrology Permafrost And Ecosystems
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Author : Daqing Yang
language : en
Publisher: Springer Nature
Release Date : 2020-08-28
Arctic Hydrology Permafrost And Ecosystems written by Daqing Yang and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-08-28 with Science categories.
This book provides a comprehensive, up-to-date assessment of the key terrestrial components of the Arctic system, i.e., its hydrology, permafrost, and ecology, drawing on the latest research results from across the circumpolar regions. The Arctic is an integrated system, the elements of which are closely linked by the atmosphere, ocean, and land. Using an integrated system approach, the book’s 30 chapters, written by a diverse team of leading scholars, carefully examine Arctic climate variability/change, large river hydrology, lakes and wetlands, snow cover and ice processes, permafrost characteristics, vegetation/landscape changes, and the future trajectory of Arctic system evolution. The discussions cover the fundamental features of and processes in the Arctic system, with a special focus on critical knowledge gaps, i.e., the interactions and feedbacks between water, permafrost, and ecosystem, such as snow pack and permafrost changes and their impacts on basin hydrology and ecology, river flow, geochemistry, and energy fluxes to the Arctic Ocean, and the structure and function of the Arctic ecosystem in response to past/future changes in climate, hydrology, and permafrost conditions. Given its scope, the book offers a valuable resource for researchers, graduate students, environmentalists, managers, and administrators who are concerned with the northern environment and resources.
Knowledge Gaps From The Ipcc Special Report On The Ocean And Cryosphere In A Changing Climate And Recent Advances
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Author : Carolina Adler
language : en
Publisher: Frontiers Media SA
Release Date : 2022-05-04
Knowledge Gaps From The Ipcc Special Report On The Ocean And Cryosphere In A Changing Climate And Recent Advances written by Carolina Adler and has been published by Frontiers Media SA this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022-05-04 with Science categories.
Meltwater Flux And Runoff Modeling In The Abalation Area Of Jakobshavn Isbrae West Greenland
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Author :
language : en
Publisher:
Release Date : 2009
Meltwater Flux And Runoff Modeling In The Abalation Area Of Jakobshavn Isbrae West Greenland written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with categories.
The temporal variability in surface snow and glacier melt flux and runoff were investigated for the ablation area of lakobshavn Isbrae, West Greenland. High-resolution meteorological observations both on and outside the Greenland Ice Sheet (GrIS) were used as model input. Realistic descriptions of snow accumulation, snow and glacier-ice melt, and runoff are essential to understand trends in ice sheet surface properties and processes. SnowModel, a physically based, spatially distributed meteorological and snow-evolution modeling system was used to simulate the temporal variability of lakobshavn Isbrre accumulation and ablation processes for 2000/01-2006/07. Winter snow-depth observations and MODIS satellite-derived summer melt observations were used for model validation of accumulation and ablation. Simulations agreed well with observed values. Simulated annual surface melt varied from as low as 3.83 x 109 m3 (2001/02) to as high as 8.64 x 109 m3 (2004/05). Modeled surface melt occurred at elevations reaching 1,870 m a.s.l. for 2004/05, while the equilibrium line altitude (ELA) fluctuated from 990 to 1,210 m a.s.l. during the simulation period. The SnowModel meltwater retention and refreezing routines considerably reduce the amount of meltwater available as ice sheet runoff; without these routines the lakobshavn surface runoff would be overestimated by an average of 80%. From September/October through May/June no runoff events were simulated. The modeled interannual runoff variability varied from 1.81 x 109 m3 (2001/02) to 5.21 x 109 m3 (2004/05), yielding a cumulative runoff at the Jakobshavn glacier terminus of ≈2.25 m w.eq. to ≈4.5 m w.eq., respectively. The average modeled lakobshavn runoff of ≈3.4 km3 y−1 was merged with previous estimates of Jakobshavn ice discharge to quantify the freshwater flux to Illulissat Icefiord. For both runoff and ice discharge the average trends are similar, indicating increasing (insignificant) influx of freshwater to the Illulissat Icefiord for the period 2000/01-2006/07. This study suggests that surface runoff forms a minor part of the overall Jakobshavn freshwater flux to the fiord: around 7% (≈3.4 km3 y−1) of the average annual freshwater flux of ≈51.0 km3 y−1 originates from the surface runoff.
Meltwater Infilltration Sic In The Accumulation Zone West Greenland Ice Sheet
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Author : Daniel J. Sturgis
language : en
Publisher:
Release Date : 2009
Meltwater Infilltration Sic In The Accumulation Zone West Greenland Ice Sheet written by Daniel J. Sturgis and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with Ice sheets categories.
Surface meltwater generated in the accumulation zone of the Greenland Ice Sheet (GrIS) will either be retained by refreezing or connect to the glacial drainage system and contribute to annual runoff. The fate of this meltwater is controlled by the infiltration process, which occurs in the presence of subfreezing snow/firnpack temperatures and ice layers. Ice layers are typically treated as impermeable horizons. However, dye-trace observations suggest ice layers do not impede flow but rather accelerate flow by destabilizing the wetting-front, forming preferential flow paths termed pipes. Until the 2008 field season, the permeability of ice layers formed in the snow/firnpack on GrIS was unmeasured. Air permeameter measurements show ice layer permeability to range from 10 -15 m 2 to 10 -12 m 2 and firn to be approximately 10 -11 m 2 . Temperature profile measurements of the snow/firnpack were recorded every 30 min during the 2007 melt season. Temperature profile data confirms piping as a mechanism for meltwater delivery to 10+ m depths at T1 without increasing the full snow/firnpack temperature to 0°C. Meltwater that is piped to the glacier-ice surface can connect to the glacial drainage system and runoff. Current models used to estimate annual runoff from GrIS do not consider the infiltration process; possibly underestimating the actual runoff.
Climate Change 2021 The Physical Science Basis
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Author : Intergovernmental Panel on Climate Change (IPCC)
language : en
Publisher: Cambridge University Press
Release Date : 2023-07-26
Climate Change 2021 The Physical Science Basis written by Intergovernmental Panel on Climate Change (IPCC) and has been published by Cambridge University Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2023-07-26 with Science categories.
The Working Group I contribution to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) provides a comprehensive assessment of the physical science basis of climate change. It considers in situ and remote observations; paleoclimate information; understanding of climate drivers and physical, chemical, and biological processes and feedbacks; global and regional climate modelling; advances in methods of analyses; and insights from climate services. It assesses the current state of the climate; human influence on climate in all regions; future climate change including sea level rise; global warming effects including extremes; climate information for risk assessment and regional adaptation; limiting climate change by reaching net zero carbon dioxide emissions and reducing other greenhouse gas emissions; and benefits for air quality. The report serves policymakers, decision makers, stakeholders, and all interested parties with the latest policy-relevant information on climate change. Available as Open Access on Cambridge Core.
Bare Ice Hydrologic Processes On The Greenland Ice Sheet Ablation Zone
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Author : Matthew Cooper
language : en
Publisher:
Release Date : 2020
Bare Ice Hydrologic Processes On The Greenland Ice Sheet Ablation Zone written by Matthew Cooper and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.
The Greenland Ice Sheet is a major contributor to global sea level rise, with recent mass loss dominated by meltwater runoff from the ablation zone, i.e. areas of the ice sheet where annual mass losses exceed gains. In this zone, the winter snowpack melts entirely each summer exposing bare glacier ice. Observations of Greenland's ablation zone suggest the exposed bare ice surface is comprised of low-density ice termed "weathering crust" that may store meltwater, potentially reducing meltwater runoff export to surrounding oceans. Climate models are the primary tools used to forecast future Greenland mass loss, but these models treat the ablation zone as impermeable high-density ice with no meltwater retention capacity. Recent evidence suggests that climate models overpredict meltwater runoff from the ablation zone, which may be linked to weathering crust presence, but diagnosing climate model predictions is difficult because observations of meltwater runoff on the ice sheet surface are extremely rare and weathering crust presence is undocumented. This dissertation presents the results of four investigations that address this problem by pairing field observations of hydrologic and radiative properties of bare ice collected in Greenland's ablation zone with numerical modeling and analysis of climate model output. The results of these investigations reveal the presence of low-density weathering crust on Greenland's bare ice ablation zone surface and the potential for non-trivial meltwater runoff retention within weathering crust on Greenland's bare ice ablation zone surface. New estimates of spectral radiation attenuation coefficients are quantified and directly applied to a numerical model of spectral and thermodynamic heat transfer in bare ice. This model successfully simulates meltwater runoff from a supraglacial catchment on Greenland's southwest ablation zone surface. Model results suggest that nocturnal refreezing of meltwater stored within weathering crust occurs in Greenland's ablation zone, potentially reducing runoff up to 32% on annual timescales. These findings imply a reinterpretation of refreezing on bare ice as an important control on Greenland's ablation zone surface mass balance and the need to represent this process in climate model predictions of future Greenland mass loss.
Snow And Glacier Hydrology
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Author : P. Singh
language : en
Publisher: Springer Science & Business Media
Release Date : 2001-02-28
Snow And Glacier Hydrology written by P. Singh and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2001-02-28 with Science categories.
This book provides an updated discussion of snow and glacier hydrology, drawing on the results of recent investigations. It serves as a source of reference at the senior undergraduate or beginning graduate level and stimulates further interest in this important part of the hydrologic cycle.
Influence Of Meltwater On Greenland Ice Sheet Dynamics
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Author : Laura A. Stevens
language : en
Publisher:
Release Date : 2017
Influence Of Meltwater On Greenland Ice Sheet Dynamics written by Laura A. Stevens and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with Glaciers categories.
Seasonal fluxes of meltwater control ice-flow processes across the Greenland Ice Sheet ablation zone and subglacial discharge at marine-terminating outlet glaciers. With the increase in annual ice sheet meltwater production observed over recent decades and predicted into future decades, understanding mechanisms driving the hourly to decadal impact of meltwater on ice flow is critical for predicting Greenland Ice Sheet dynamic mass loss. This thesis investigates a wide range of meltwater-driven processes using empirical and theoretical methods for a region of the western margin of the Greenland Ice Sheet. I begin with an examination of the seasonal and annual ice flow record for the region using in situ observations of ice flow from a network of Global Positioning System (GPS) stations. Annual velocities decrease over the seven-year time-series at a rate consistent with the negative trend in annual velocities observed in neighboring regions. Using observations from the same GPS network, I next determine the trigger mechanism for rapid drainage of a supraglacial lake. In three consecutive years, I find precursory basal slip and uplift in the lake basin generates tensile stresses that promote hydrofracture beneath the lake. As these precursors are likely associated with the introduction of meltwater to the bed through neighboring moulin systems, our results imply that lakes may be less able to drain in the less crevassed, interior regions of the ice sheet. Expanding spatial scales to the full ablation zone, I then use a numerical model of subglacial hydrology to test whether model-derived effective pressures exhibit the theorized inverse relationship with melt-season ice sheet surface velocities. Finally, I pair near-ice fjord hydrographic observations with modeled and observed subglacial discharge for the Saqqardliup sermia–Sarqardleq Fjord system. I find evidence of two types of glacially modified waters whose distinct properties and locations in the fjord align with subglacial discharge from two prominent subcatchments beneath Saqqardliup sermia. Continued observational and theoretical work reaching across discipline boundaries is required to further narrow our gap in understanding the forcing mechanisms and magnitude of Greenland Ice Sheet dynamic mass loss.
Glacier Hydrology And Hydrochemistry
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Author : M. Sharp
language : en
Publisher: John Wiley & Sons
Release Date : 1998-10-20
Glacier Hydrology And Hydrochemistry written by M. Sharp and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 1998-10-20 with Science categories.
The last decade has been a period of rapid advances in glacier hydrology and hydrochemistry. These have resulted from the application of new technologies to the direct observation of englacial and subglacial drainage systems via boreholes, from theoretical advances and from increased interactions between fieldworkers and modellers. This collection of papers captures the spirit of these advances highlighting new methodologies, the change in character of hydrological models from lumped conceptual models to physically based, distributed models, and the changing role of field studies in glacier hydrological investigations. Major themes identified in the book are: approaches to defining the structure of drainage systems in cold and temperate glaciers; investigations of the linkages between surface and subsurface components of these systems, and of hydraulic interactions between different elements of subglacial systems; seasonal changes in drainage system properties at local and glacier wide scales; controls on meltwater quality; the integration of field and modelling studies; and problems of scaling up results from studies of valley glaciers to the ice sheet scale.
