[PDF] Improving The Physical Processes And Model Integration Functionality Of An Energy Balance Model For Snow And Glacier Melt eBook

Author : Avirup Sen Gupta
Publisher :
Page : pages
File Size : 33,25 MB
Release : 2014
Category :
ISBN :

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The Hindu-Kush Himalayan region possesses a large resource of snow and ice, which acts as a freshwater reservoir for irrigation, domestic water consumption or hydroelectric power for billions of people in South Asia. Monitoring hydrologic resources in this region is challenging because of the difficulty of installing and maintaining a climate and hydrologic monitoring network, limited transportation and communication infrastructure and difficult access to glaciers. As a result of the high, rugged topographic relief, ground observations in the region are extremely sparse. Reanalysis data offer the potential to compensate for the data scarcity, which is a barrier in hydrological modeling and analysis for improving water resources management. Reanalysis weather data products integrate observations with atmospheric model physics to produce a spatially and temporally complete weather record in the post-satellite era. This dissertation creates an integrated hydrologic modeling system that tests whether streamflow prediction can be improved by taking advantage of the National Aeronautics and Space Administration (NASA) remote sensing and reanalysis weather data products in physically based energy balance snow melt and hydrologic models. This study also enhances the energy balance snowmelt model by adding capability to quantify glacier melt. The novelty of this integrated modeling tool resides in allowing the user to isolate various components of surface water inputs (rainfall, snow and glacier ice melt) in a cost-free, open source graphical-user interface-based system that can be used for government and institutional decision-making. Direct, physically based validation of this system is challenging due to the data scarcity in this region, but, to the extent possible, the model was validated through comparison to observed streamflow and to point measurements at locations in the United States having available data

Author : W. Tad Pfeffer
Publisher : Frontiers Media SA
Page : 160 pages
File Size : 47,69 MB
Release : 2018-11-08
Category :
ISBN : 2889456196

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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.

Author : Federico Covi
Publisher :
Page : 0 pages
File Size : 10,56 MB
Release : 2022
Category : Firn
ISBN :

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Increased surface melt in the percolation zone of Greenland causes significant changes in the firn structure, directly affecting the surface mass balance of the ice sheet and the amount and timing of meltwater runoff. Thick impermeable layers, referred to as ice slabs, are preventing melt water percolation and refreezing in the firn favoring lateral movement of water and direct runoff to the oceans. The objective of this dissertation is to enhance the understanding of these processes by modeling the surface energy balance and resulting melt, and investigating the spatial and temporal changes in firn surface properties and associated water movement in the percolation zone in southwest Greenland. Extensive fieldwork was carried out in this region between 2017 and 2019, including a collection of 19 shallow firn cores at several sites and the operation of two weather stations. A surface-energy balance model was forced with automatic weather station data from two sites (2040 and 2360 m a.s.l.). Extensive model validation and sensitivity analysis reveal that the skin layer formulation used to compute the surface temperature by closing the energy balance leads to a consistent overestimation of melt by more than a factor of two or three depending on the site. The results indicate that the energy available for melt is highly sensitive to small changes in surface temperature and suggests caution is needed in modeling Greenland melt from weather data. Furthermore, the spatial and temporal variability in air temperature bias of two regional climate models, MAR and RACMO, is assessed over the entire ice sheet. Model results are compared to 35 automatic weather stations over more than 25 years. Both models perform well in the ablation zone ( 1500 m a.s.l.) where most of the melt happens. However, a warm bias is found in both MAR and RACMO at the higher elevations percolation zone ( 1500 m a.s.l.). The seasonal evolution and interannual variability of near-surface firn characteristics in the percolation zone of southwest Greenland can be tracked with Sentinel-2 optical imagery. Fully saturated seasonal snow (blue slush) and lateral movement of water are strongly correlated with local topography. Furthermore there is evidence of water movement from higher to lower elevations, following surface slope, even after the halting of melt in the second half of August. This suggests that the formation of ice slabs is a self-sustained feedback process increasing the efficiency of the runoff networks in the percolation zone. Ice slabs form and become thicker in areas with smaller surface slope than the surroundings where melt water ponds on top of the impermeable layer, flows, and refreezes during fall, adding to the ice slab. This dissertation provides useful insights on the processes driving ongoing changes in the percolation zone of Greenland due to global warming. However, several questions remain still open. Melt is the main driver of changes. Accurately modeling it, solving the uncertainties in observed and modeled sensible and ground heat flux, is essential. Furthermore, more ground truth and field observations are necessary in the region where blue slush forms on top of ice slabs to quantitatively determine how much water leaves the ice sheet and how much instead refreezes thickening the ice slabs.

Author : V. Alexiades
Publisher : Routledge
Page : 342 pages
File Size : 23,34 MB
Release : 2018-05-02
Category : Science
ISBN : 135143327X

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This reference book presents mathematical models of melting and solidification processes that are the key to the effective performance of latent heat thermal energy storage systems (LHTES), utilized in a wide range of heat transfer and industrial applications. This topic has spurred a growth in research into LHTES applications in energy conservation and utilization, space station power systems, and thermal protection of electronic equipment in hostile environments. Further, interest in mathematical modeling has increased with the speread of high powered computers used in most industrial and academic settings. In two sections, the book first describes modeling of phase change processes and then describes applications for LHTES. It is aimed at graduate students, researchers, and practicing engineers in heat transfer, materials processing, multiphase systems, energy conservation, metallurgy, microelectronics, and cryosurgery.

Author : Ryan J. Johnson
Publisher :
Page : 106 pages
File Size : 27,12 MB
Release : 2015
Category : Ice
ISBN : 9781339054858

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Many snow models in the field of hydrologic engineering do not incorporate the long-term effects of the interannual snow storage such as glaciers because glacier dynamics have a much longer timescale than river flow and seasonal snowmelt. This study proposes an appropriate treatment for inland glaciers as systems in dynamic equilibrium that remain constant under a static climate condition. This new method considers the vertical movement of snow/ice from high elevation areas to valleys as the equilibrating factor of the glacier system. The vertical movement of snow/ice occurs by means of wind re-distribution, avalanches, and glaciation. This paper introduces and discusses the physically-based modeling of such a dynamic equilibrium snow system for long-term snow simulation at a regional scale. We apply the regional snow model (RegSnow) to a domain containing the entire state of Wyoming and couple the model to the Weather Research and Forecasting (WRF) model to compute the snow surface energy-balance. RegSnow predicted that 82.2% of interannual snow and ice storage in Wyoming may disappear by 2100 using temperature increases projected by CMIP5 GCMs, under the RCP4.5 emission scenario.

Author : Richard L. Armstrong
Publisher : Cambridge University Press
Page : 4 pages
File Size : 48,19 MB
Release : 2008-04-24
Category : Science
ISBN : 0521854547

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This book presents the prevailing state of snow-climate science for researchers and advanced students.

Author : Gerald R. North
Publisher : John Wiley & Sons
Page : 389 pages
File Size : 41,95 MB
Release : 2017-08-02
Category : Science
ISBN : 3527683836

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Energy Balance Climate Models Written by renowned experts in the field, this first book to focus exclusively on energy balance climate models provides a concise overview of the topic. It covers all major aspects, from the simplest zero-dimensional models, proceeding to horizontally and vertically resolved models. The text begins with global average models, which are explored in terms of their elementary forms yielding the global average temperature, right up to the incorporation of feedback mechanisms and some analytical properties of interest. The eff ect of stochastic forcing is then used to introduce natural variability in the models before turning to the concept of stability theory. Other one dimensional or zonally averaged models are subsequently presented, along with various applications, including chapters on paleoclimatology, the inception of continental glaciations, detection of signals in the climate system, and optimal estimation of large scale quantities from point scale data. Throughout the book, the authors work on two mathematical levels: qualitative physical expositions of the subject material plus optional mathematical sections that include derivations and treatments of the equations along with some proofs of stability theorems. A must-have introduction for policy makers, environmental agencies, and NGOs, as well as climatologists, molecular physicists, and meteorologists.

Author : National Research Council
Publisher : National Academies Press
Page : 218 pages
File Size : 46,39 MB
Release : 2012-11-29
Category : Science
ISBN : 0309261015

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Scientific evidence shows that most glaciers in South Asia's Hindu Kush Himalayan region are retreating, but the consequences for the region's water supply are unclear, this report finds. The Hindu Kush Himalayan region is the location of several of Asia's great river systems, which provide water for drinking, irrigation, and other uses for about 1.5 billion people. Recent studies show that at lower elevations, glacial retreat is unlikely to cause significant changes in water availability over the next several decades, but other factors, including groundwater depletion and increasing human water use, could have a greater impact. Higher elevation areas could experience altered water flow in some river basins if current rates of glacial retreat continue, but shifts in the location, intensity, and variability of rain and snow due to climate change will likely have a greater impact on regional water supplies. Himalayan Glaciers: Climate Change, Water Resources, and Water Security makes recommendations and sets guidelines for the future of climate change and water security in the Himalayan Region. This report emphasizes that social changes, such as changing patterns of water use and water management decisions, are likely to have at least as much of an impact on water demand as environmental factors do on water supply. Water scarcity will likely affect the rural and urban poor most severely, as these groups have the least capacity to move to new locations as needed. It is predicted that the region will become increasingly urbanized as cities expand to absorb migrants in search of economic opportunities. As living standards and populations rise, water use will likely increase-for example, as more people have diets rich in meat, more water will be needed for agricultural use. The effects of future climate change could further exacerbate water stress. Himalayan Glaciers: Climate Change, Water Resources, and Water Security explains that changes in the availability of water resources could play an increasing role in political tensions, especially if existing water management institutions do not better account for the social, economic, and ecological complexities of the region. To effectively respond to the effects of climate change, water management systems will need to take into account the social, economic, and ecological complexities of the region. This means it will be important to expand research and monitoring programs to gather more detailed, consistent, and accurate data on demographics, water supply, demand, and scarcity.

Author :
Publisher :
Page : 222 pages
File Size : 23,28 MB
Release : 2008
Category : Climatic changes
ISBN : 9780511455339

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This book presents the current state of snow-climate science for researchers and advanced students.