Energetics of Surface Melt in West Antarctica PDF Download
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Author: Madison Ghiz
Publisher:
ISBN:
Category :
Languages : en
Pages : 100
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Book Description
Surface melting is an important mass loss process from ice sheets. In West Antarctica, the lack of direct surface observations poses difficulties in studying surface melt and loss of ice mass. This thesis presents seven contrasting cases in which surface melt was detected by satellite passive microwave sensors and analyzed using both reanalysis data and satellite data. During these melt events meteorological conditions caused the total melt energy to elevate for anywhere between 3-8 days, compared with the rest of the month. This elevated melt energy can be induced by four main mechanisms typical of the austral summer climate described in this study. These mechanisms are thermal blanketing from optically thick clouds; thin clouds enhancing all-wave radiation at the surface; sensible heat flux preconditioning the surface to melt; and föhn wind presence on the lee side of mountains. The study locations are Siple Dome, Pine Island and Thwaites Glaciers, the southern portion of the Ross Ice Shelf, and the Larsen C Ice Shelf. Through assessing the surface energy budget, total melt energy, temperature and wind components, and cloud microphysics with regards to both 25-km resolution and small-scale spatial variability, the importance of using the highest resolution data available is demonstrated. This study not only defines drivers of West Antarctic melt, but identifies improvements that could be made to the methods and data sets used to quantify the climatology of surface melt.
Author: Madison Ghiz
Publisher:
ISBN:
Category :
Languages : en
Pages : 100
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Book Description
Surface melting is an important mass loss process from ice sheets. In West Antarctica, the lack of direct surface observations poses difficulties in studying surface melt and loss of ice mass. This thesis presents seven contrasting cases in which surface melt was detected by satellite passive microwave sensors and analyzed using both reanalysis data and satellite data. During these melt events meteorological conditions caused the total melt energy to elevate for anywhere between 3-8 days, compared with the rest of the month. This elevated melt energy can be induced by four main mechanisms typical of the austral summer climate described in this study. These mechanisms are thermal blanketing from optically thick clouds; thin clouds enhancing all-wave radiation at the surface; sensible heat flux preconditioning the surface to melt; and föhn wind presence on the lee side of mountains. The study locations are Siple Dome, Pine Island and Thwaites Glaciers, the southern portion of the Ross Ice Shelf, and the Larsen C Ice Shelf. Through assessing the surface energy budget, total melt energy, temperature and wind components, and cloud microphysics with regards to both 25-km resolution and small-scale spatial variability, the importance of using the highest resolution data available is demonstrated. This study not only defines drivers of West Antarctic melt, but identifies improvements that could be made to the methods and data sets used to quantify the climatology of surface melt.
Author: Ryan Scott
Publisher:
ISBN:
Category :
Languages : en
Pages : 172
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Book Description
West Antarctica is experiencing rapid ice loss and complex regional climate change. This dissertation investigates how cloud properties and the large-scale atmospheric circulation influence surface heat exchange and melting on West Antarctic ice shelves and ice sheet margins using field measurements, satellite observations, and atmospheric reanalysis data. Surface-based shortwave spectral irradiance measurements and satellite data reveal strong orographic controls on West Antarctic cloud formation and ice-phase microphysics. Orographically-forced updrafts and waves favor rapid conversion of supercooled liquid water into ice, which efficiently attenuates incoming solar near-infrared energy. Frequent intrusions of marine air from the Amundsen Sea anchor a semipermanent cloud band over the West Antarctic Ice Sheet (WAIS) that continues downstream along the Transantarctic Mountain range. Cloud systems sampled downstream at Ross Island tend to be optically thin and radiatively dominated by ice water. In contrast, direct onshore flows of marine air from the Southern Ocean bring low clouds with enhanced liquid-phase spectral signatures. Radiative transfer calculations using vertically-resolved cloud data indicate that, owing to a dominance of longwave effects, clouds radiatively warm the surface of the WAIS in every month of the year. On annual average, cloud cover is estimated to warm the grounded ice-sheet by 34 Watts per square-meter. Thin low-level liquid-bearing clouds, which favor strong radiative heat input to the snow surface, are common during the summer melt season. Summer atmospheric warming in West Antarctica is favored by blocking activity over the Amundsen Sea and a negative phase of the Southern Annular Mode, which both correlate with El Niño conditions in the tropical Pacific Ocean. Extensive melt events on the Ross and Pacific-sector coastal ice shelves are linked to persistent, intense Amundsen Sea anticyclones, which force intrusions of marine air over the ice-sheet. Surface melting is driven by enhanced downwelling longwave radiation from clouds and a warm, moist atmosphere and by downward turbulent mixing of sensible heat by föhn winds. Since the late 1990s, concurrent with accelerating ocean-driven WAIS mass loss, summer surface melt occurrence has increased from the Pine Island and Thwaites Glacier systems to the eastern Ross Ice Shelf, linked to increasing anticyclonic marine influence and regional sea-ice loss.
Author: Xun Zou
Publisher:
ISBN:
Category : Atmospheric physics
Languages : en
Pages : 135
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Book Description
The Ross Ice Shelf buttresses ice streams from the Antarctic continent and restrains the grounded ice sheet from flowing into the ocean. Mostly affected by large-scale of atmospheric variability, West Antarctica has undergone some surface warming. In the Antarctic Peninsula (AP), the increasing trend of summer surface air temperature since the 1950s is contributing to the break-up of ice shelves, promoting glacier acceleration and ultimately increase ice loss and sea level rise. The mass loss from the West Antarctic Ice Sheet has increased in the past two decades, especially around the Amundsen and Bellingshausen Sea regions. For areas like the AP, surface melting plays a significant role in the ice shelf loss. Over most ice shelves outside of the AP, basal melting dominates surface ice shelf thinning at present. However, according to climate model projections, substantial surface melting may occur in West Antarctica in the future, especially over the Ross Ice Shelf. It is unclear if this projected surface melting will also result in continental ice loss as it has and continues to do in the AP.
Author: Roger G. Barry
Publisher: Cambridge University Press
ISBN: 1108423167
Category : History
Languages : en
Pages : 445
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Book Description
Surveys atmospheric, oceanic and cryospheric processes, present and past conditions, and changes in polar environments.
Author: Xun Zou
Publisher:
ISBN:
Category : Atmospheric science
Languages : en
Pages : 226
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Book Description
This study first investigates the foehn effect at the beginning of the 2016 event via the AMPS output. The foehn effect increases surface temperature by up to 4 oC on the leeside of the coastal mountains over Marie Byrd Land and around 1 o C over mountain ranges in Edward VII Peninsula. Dry adiabatic warming triggered by isentropic drawdown is the dominant contributor, followed by sensible heat flux resulting from the turbulence, and lastly thermodynamic heating sourced from latent heat release on the upwind side.
Author: Eugene Domack
Publisher: American Geophysical Union
ISBN:
Category : Nature
Languages : en
Pages : 280
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Book Description
Published by the American Geophysical Union as part of the Antarctic Research Series, Volume 79. The Antarctic Peninsula region represents our best natural laboratory to investigate how earth's major climate systems interact and how such systems respond to rapid regional warming. The scale of environmental changes now taking place across the region is large and their pace rapid but the subsystems involved are still small enough to observe and accurately document cause and affect mechanisms. For example, clarification of ice shelf stability via the Larsen Ice Shelf is vital to understanding the entire Antarctic Ice Sheet, its climate evolution, and its response to and control of sea level. By encompassing the broadest range of interdisciplinary studies, this volume provides the global change research and educational communities a framework in which to advance our knowledge of the causes behind regional warming, the dramatic glacial and ecological responses, and the potential uniqueness of the event within the region's paleoclimate record. The volume also serves as a vital resource for public policy and governmental funding agencies as well as a means to educate the large number of ecotourists that visit the region each austral summer.
Author: Christopher Karmosky
Publisher:
ISBN:
Category :
Languages : en
Pages : 111
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Book Description
Author: C.J. van der Veen
Publisher: Springer Science & Business Media
ISBN: 9400937458
Category : Science
Languages : en
Pages : 376
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Book Description
Few scientists doubt the prediction that the antropogenic release of carbon dioxide in the atmosphere will lead to some warming of the earth's climate. So there is good reason to investigate the possible effects of such a warming, in dependence of geographical and social economic setting. Many bodies, governmental or not, have organized meetings and issued reports in which the carbon dioxide problem is defined, reviewed, and possible threats assessed. The rate at which such reports are produced still increases. However, while more and more people are getting involved in the 'carbon dioxide business', the number of investigators working on the basic problems grows, in our view, too slowly. Many fundamental questions are still not answered in a satisfactory way, and the carbon dioxide building rests on a few thin pillars. One such fundamental question concerns the change in sea level associated with a climatic warming of a few degrees. A number of processes can be listed that could all lead to changes of the order of tens of centimeters (e. g. thermal expansion, change in mass balance of glaciers and ice sheets). But the picture of the carbon dioxide problem has frequently be made more dramatic by suggesting that the West Antarctic Ice Sheet is unstable, implying a certain probability of a 5 m higher sea-level stand within a few centuries.
Author: Vijay P. Singh
Publisher: Springer Science & Business Media
ISBN: 9048126428
Category : Science
Languages : en
Pages : 1301
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Book Description
The earth’s cryosphere, which includes snow, glaciers, ice caps, ice sheets, ice shelves, sea ice, river and lake ice, and permafrost, contains about 75% of the earth’s fresh water. It exists at almost all latitudes, from the tropics to the poles, and plays a vital role in controlling the global climate system. It also provides direct visible evidence of the effect of climate change, and, therefore, requires proper understanding of its complex dynamics. This encyclopedia mainly focuses on the various aspects of snow, ice and glaciers, but also covers other cryospheric branches, and provides up-to-date information and basic concepts on relevant topics. It includes alphabetically arranged and professionally written, comprehensive and authoritative academic articles by well-known international experts in individual fields. The encyclopedia contains a broad spectrum of topics, ranging from the atmospheric processes responsible for snow formation; transformation of snow to ice and changes in their properties; classification of ice and glaciers and their worldwide distribution; glaciation and ice ages; glacier dynamics; glacier surface and subsurface characteristics; geomorphic processes and landscape formation; hydrology and sedimentary systems; permafrost degradation; hazards caused by cryospheric changes; and trends of glacier retreat on the global scale along with the impact of climate change. This book can serve as a source of reference at the undergraduate and graduate level and help to better understand snow, ice and glaciers. It will also be an indispensable tool containing specialized literature for geologists, geographers, climatologists, hydrologists, and water resources engineers; as well as for those who are engaged in the practice of agricultural and civil engineering, earth sciences, environmental sciences and engineering, ecosystem management, and other relevant subjects.
Author: National Research Council
Publisher: National Academies Press
ISBN: 0309171113
Category : Science
Languages : en
Pages : 139
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Book Description
The high latitudes of the Arctic and Antarctic, together with some mountainous areas with glaciers and long-lasting snow, are sometimes called the cryosphere-defined as that portion of the planet where water is perennially or seasonally frozen as sea ice, snow cover, permafrost, ice sheets, and glaciers. Variations in the extent and characteristics of surface ice and snow in the high latitudes are of fundamental importance to global climate because of the amount of the sun's radiation that is reflected from these often white surfaces. Thus, the cryosphere is an important frontier for scientists seeking to understand past climate events, current weather, and climate variability. Obtaining the data necessary for such research requires the capability to observe and measure a variety of characteristics and processes exhibited by major ice sheets and large-scale patterns of snow and sea ice extent, and much of these data are gathered using satellites. As part of its efforts to better support the researchers studying the cryosphere and climate, the National Aeronautics and Space Administration (NASA)-using sophisticated satellite technology-measures a range of variables from atmospheric temperature, cloud properties, and aerosol concentration to ice sheet elevation, snow cover on land, and ocean salinity. These raw data are compiled and processed into products, or data sets, useful to scientists. These so-called "polar geophysical data sets" can then be studied and interpreted to answer questions related to atmosphere and climate, ice sheets, terrestrial systems, sea ice, ocean processes, and many other phenomena in the cryosphere. The goal of this report is to provide a brief review of the strategy, scope, and quality of existing polar geophysical data sets and help NASA find ways to make these products and future polar data sets more useful to researchers, especially those working on the global change questions that lie at the heart of NASA's Earth Science Enterprise.
