Effects Of Changes In Moisture Source And The Upstream Rainout On Stable Isotopes In Precipitation – A Case Study In Nanjing, Eastern China, Y. Tang, H. Pang, W. Zhang, Y. Li, Shuang-Ye Wu, S. Hou
Geology Faculty Publications
In the Asian monsoon region, variations in the stable isotopic composition of speleothems have often been attributed to the "amount effect". However, an increasing number of studies suggest that the "amount effect" in local precipitation is insignificant or even non-existent. To explore this issue further, we examined the variability of daily stable isotopic composition (δ18O) in precipitation from September 2011 to November 2014 in Nanjing, eastern China. We found that intra-seasonal variations of δ18O during summer were not significantly correlated with local rainfall amount but could be linked to changes in the moisture source location and rainout processes in the ...
Geology Of The Steens Area, 2015 Linfield College
Geology Of The Steens Area, Jane Claire Dirks-Edmunds
Jane Claire Dirks-Edmunds Documents
This document is part of a larger discussion in the Dr. Jane Claire Dirks-Edmunds Papers on the geology of Steens Mountain, a large fault-block mountain in Harney County, Oregon. Often confused for a mountain range because of its size and scope, Steens Mountain lies near the Oregon-Nevada border.
For a full-text searchable version of this document, refer to the Additional Files below.
Coastal Ice-Core Record Of Recent Northwest Greenland Temperature And Sea-Ice Concentration, 2015 Dartmouth College
Coastal Ice-Core Record Of Recent Northwest Greenland Temperature And Sea-Ice Concentration, Erich C. Osterberg, Robert L. Hawley, Gifford Wong, Ben Kopec, David Ferris, Jennifer Howley
Open Dartmouth: Faculty Open Access Articles
Coastal ice cores provide an opportunity to investigate regional climate and sea-ice variability in the past to complement hemispheric-scale climate reconstructions from ice-sheet-interior ice cores. Here we describe robust proxies of Baffin Bay temperature and sea-ice concentration from the coastal 2Barrel ice core collected in the Thule region of northwest Greenland. Over the 1990–2010 record, 2Barrel annually averaged methanesulfonic acid (MSA) concentrations are significantly correlated with May–June Baffin Bay sea-ice concentrations and summer temperatures. Higher MSA is observed during warmer years with less sea ice, indicative of enhanced primary productivity in Baffin Bay. Similarly, 2Barrel annually averaged deuterium ...
Putting The West Antarctic Ice Sheet Into Context, 2015 Principal Investigator; University of Maine, Orono
Putting The West Antarctic Ice Sheet Into Context, George H. Denton, Brenda L. Hall
University of Maine Office of Research and Sponsored Programs: Grant Reports
This award supports a project to develop new insights into the cause and pattern of events during the last glacial termination in South America and Antarctica. One emerging view is that a warming Southern Ocean (SO), driven by a chain of events initiated in the Northern Hemisphere (NH) and tied to the interhemispheric climate seesaw of the last termination, was the underlying mechanism that drove the West Antarctic ice sheet (WAIS) from its Late Glacial Maximum (LGM) position back to present-day grounding lines. This ocean thermal forcing would have impacted WAIS by accelerating basal melt rates on fringing floating ice ...
Dynamics Of Thermally Induced Ice Streams Simulated With A Higher-Order Flow Model, 2015 University of Alaska Fairbanks
Dynamics Of Thermally Induced Ice Streams Simulated With A Higher-Order Flow Model, Douglas Brinkerhoff, Jesse Johnson
Computer Science Faculty Publications
We use a new discretization technique to solve the higher-order thermomechanically coupled equations of glacier evolution. We find that under radially symmetric continuum equations, small perturbations in symmetry due to the discretization are sufficient to produce the initiation of non-symmetric thermomechanical instabilities which we interpret as ice streams, in good agreement with previous studies which have indicated a similar instability. We find that the inclusion of membrane stresses regularizes the size of predicted streams, eliminating the ill-posedness evident in previous investigations of ice stream generation through thermomechanical instability. Ice streams exhibit strongly irregular periodicity which is influenced by neighboring ice ...
Near-Surface Internal Melting: A Substantial Mass Loss On Antarctic Dry Valley Glaciers, 2015 Los Alamos National Laboratory
Near-Surface Internal Melting: A Substantial Mass Loss On Antarctic Dry Valley Glaciers, Matthew J. Hoffman, Andrew G. Fountain, Glen E. Liston
Andrew G. Fountain
The McMurdo Dry Valleys, southern Victoria Land, East Antarctica, are a polar desert, and melt from glacial ice is the primary source of water to streams, lakes and associated ecosystems. Previous work found that to adequately model glacier ablation and subsurface ice temperatures with a surface energy-balance model required including the transmission of solar radiation into the ice. Here we investigate the contribution of subsurface melt to the mass balance of (and runoff from) Dry Valley glaciers by including a drainage process in the model and applying the model to three glacier sites using 13years of hourly meteorological data. Model ...
Glacier Change On The Three Sisters Volcanoes, Oregon: 1900-2010, 2015 Portland State University
Glacier Change On The Three Sisters Volcanoes, Oregon: 1900-2010, Justin George Ohlschlager
Dissertations and Theses
A glacier responds to changes in climate by subsequent retreat and advance as a result of changes in snow inputs and outputs. Understanding these changes is important because shrinking glaciers limit and diminish local water resources. They contribute to alpine runoff in the late-summer months by delaying the maximum runoff until late in the melt season. A comprehensive glacier and perennial snowfield inventory has not been completed for the Three Sisters in Central Oregon. Using aerial photography, Digital Elevation Models (DEMs), previous studies, and historical ground based photographs these glacier and perennial snowfields were defined and their surface area change ...
Temperature Distribution And Thermal Anomalies Along A Flowline Of The Greenland Ice Sheet, 2015 University of Wyoming
Temperature Distribution And Thermal Anomalies Along A Flowline Of The Greenland Ice Sheet, Joel A. Harrington, Neil F. Humphrey, Joel T. Harper
Geosciences Faculty Publications
Englacial and basal temperature data for the Greenland ice sheet (GrIS) are sparse and mostly limited to deep interior sites and ice streams, providing an incomplete representation of the thermal state of ice within the ablation zone. Here we present 11 temperature profiles at five sites along a 34km east-west transect of West Greenland. These profiles depict ice temperatures along a flowline and local temperature variations between closely spaced boreholes. A temperate basal layer is present in all profiles, increasing in thickness in the flow direction, where it expands from about 3% of ice height furthest inland to 100% at ...
Evidence Of Late Quaternary Fires From Charcoal And Siliceous Aggregates In Lake Sediments In The Eastern U.S.A., 2015 University of Tennessee - Knoxville
Evidence Of Late Quaternary Fires From Charcoal And Siliceous Aggregates In Lake Sediments In The Eastern U.S.A., Joanne P. Ballard
The late-glacial transition to the Holocene, 15,000–11,600 cal yr BP, is an enigmatic period of dynamic global changes and a major extinction event in North America. Fire is an agent of disturbance that transforms the environment physically and chemically, and affects plant community composition. To improve understanding of the linkages between fire, vegetation, and climate over the late glacial and Holocene in the eastern U.S., I analyzed lake-sediment cores for charcoal and indicators of wood ash, and compared results to existing pollen records. A new microscopic charcoal record from Anderson Pond, Tennessee revealed high fire activity ...
Timing And Extent Of The Little Ice Age Glacial Advances In The Eastern Tian Shan, China, 2015 University of Tennessee - Knoxville
Timing And Extent Of The Little Ice Age Glacial Advances In The Eastern Tian Shan, China, Yanan Li
Located in Central Asia, one of the most continental regions on Earth, the Tian Shan’s glaciers contribute critical fresh water to populated areas in the lowland. These glaciers are sensitive to climate change, and knowledge of contemporary glaciers and their changes in the past is of critical importance for sustainable development in this region. Constraining glacial fluctuations in recent centuries will fill a gap in numerical constraints on glacial history and paleoclimate information, and provide important evidence on the spatio-temporal changes of the climate systems in the Tian Shan. This doctoral dissertation investigates the timing and extent of Little ...
Establishing A Chronology Of Late Quaternary Glacial Advances In The Cordillera De Talamanca, Costa Rica, 2015 University of Tennessee - Knoxville
Establishing A Chronology Of Late Quaternary Glacial Advances In The Cordillera De Talamanca, Costa Rica, Rebecca Susan Potter
Little research has focused on glacial events in the tropics. Providing an absolute glacial chronology in Costa Rica will build a foundation for future glacial chronologies and paleoclimate reconstructions in the highlands of Central America. Evidence of past glaciation, including moraines and glacial lakes, is preserved within formerly glaciated valleys in the Cordillera de Talamanca. Orvis and Horn (2000) constrained deglaciation ages of the most recent glacial event in the Cordillera de Talamanca based on radiocarbon dates of glacial lake sediments. Radiocarbon ages indicated complete deglaciation after 12.4 ka cal BP but before 9.7 ka cal BP (Orvis ...
Dye Tracing To Determine Flow Properties Of Hydrocarbon-Polluted Rabots Glaciär, Kebnekaise, Sweden, 2015 Stockholm University
Dye Tracing To Determine Flow Properties Of Hydrocarbon-Polluted Rabots Glaciär, Kebnekaise, Sweden, Caroline C. Clason, C. Coch, J. Jarsjö, Keith A. Brugger, P. Jansson, G. Rosqvist
Over 11 000 L of kerosene was deposited on the surface of Rabots glaciär on the Kebnekaise Massif, northern Sweden, following the crash of a Royal Norwegian Air Force aircraft in March 2012. An environmental monitoring programme was subsequently commissioned, including a series of dye tracing experiments during the 2013 melt season, conducted to investigate the transport of pollutants through the glacier hydrological system. This experimental set-up provided a basis from which we could gain new insight into the internal hydrological system of Rabots glaciär. Results of dye tracing experiments reveal a degree of homogeneity in the topology of the ...
Roosevelt Island Climate Evolution Project (Rice): Us Deep Ice Core Glaciochemistry Contribution (2011- 2014), 2015 Principal Investigator; University of Maine, Orono
Roosevelt Island Climate Evolution Project (Rice): Us Deep Ice Core Glaciochemistry Contribution (2011- 2014), Paul Andrew Mayewski, Karl J. Kreutz, Andrei V. Kurbatov
University of Maine Office of Research and Sponsored Programs: Grant Reports
This award supports a project to analyze a deep ice core which will be drilled by a New Zealand research team at Roosevelt Island. The objectives are to process the ice core at very high resolution to (a) better understand phasing sequences in Arctic/Antarctic abrupt climate change, even at the level of individual storm events; (b) determine the impact of changes in the Westerlies and the Amundsen Sea Low on past/present/future climate change; (c) determine how sea ice extent has varied in the area; (d) compare the response of West Antarctica climate to other regions during glacial ...
Interface Friction Parameters For The Mathematical Modeling Of Shell Structures With Infill, 2015 Far Eastern Federal University
Interface Friction Parameters For The Mathematical Modeling Of Shell Structures With Infill, Alexander T. Bekker, Nikita Ya. Tsimbelman, Tatiana I. Chernova, Vadim D. Bruss, Ömer Bilgin
Civil and Environmental Engineering and Engineering Mechanics Faculty Publications
Thin metal or reinforced concrete shells with granular infill structures are considered in this article. These structures are massive and they are used as support for the construction of berthing quays, piers, artificial islands, shore protection, and other structures of coastal infrastructure. It is more convenient to use the thin shell structures during the development of the Arctic shelf, because it is possible to install them from the ice side. In addition, it is possible to enhance the technology and install thin shells with infill on deeper solid foundation layers. A mathematical model for the stresses on a compressible foundation ...
Experimental Recreation Of The Sub-Glacial System, An Analysis Of Hold Time Versus Strengthening To Shed Light On The Mechanics Of Stick-Slip Ice Streams, Ian Mcbrearty
Symposium on Undergraduate Research and Creative Expression
Ice streams in Antarctica are known to move ice rapidly, in a narrow band, over a loose permeable substrate to the sea- contributing to sea-level rise and the decay of the Antarctic Ice Sheet. It has been observed that some of these ice streams move in a “stick-slip” fashion, lurching ahead small steps at a time. Past workers have proposed this observation is indicative of temporal strengthening in the ice stream when it’s sitting at rest, but have not satisfactorily concluded which components of the glacial system are directly causing the strengthening. To understand the mechanics dictating ice stream ...
Reconstructing Thermal Properties Of Firn At Summit, Greenland, From A Temperature Profile Time Series, Alexandra L. Giese, Robert L. Hawley
Open Dartmouth: Faculty Open Access Articles
We have constrained the value for thermal diffusivity of near-surface snow and firn at Summit Station, Greenland, using a Fourier-type analysis applied to hourly temperature measurements collected from eight thermistors in a closed-off, air-filled borehole between May 2004 and July 2008. An implicit, finite-difference method suggests that a bulk diffusivity of ∼25 ± 3m2 a−1 is the most reasonable for representing macroscale heat transport in the top 30 m of firn and snow. This value represents an average diffusivity and, in a conduction-only model, generates temperature series whose phase shifts with depth most closely match those of the Summit borehole ...
Determining Provenance Of Glacial Material In Southwestern Ohio, 2015 Cedarville University
Determining Provenance Of Glacial Material In Southwestern Ohio, Jorian Krob
The Research and Scholarship Symposium
During the last glacial maximum, ice moved south from Canada to cover much of the northern United States. This included the northern and western portions of Ohio. As the ice migrated it picked up Canadian bedrock which it transported and then left in Ohio when the ice retreated. The goal of this project was to determine the provenance (the source of origin) of the glacial material that is located in Greene, Clark, Montgomery, Logan, and Champaign Counties in Ohio. To determine where in southern Canada the material in these counties came from, this project included literature review into the glacial ...
Glacial Till Prospecting In Southwest Ohio: Implications For Improved Sampling, 2015 Cedarville University
Glacial Till Prospecting In Southwest Ohio: Implications For Improved Sampling, Dylan J. Mckevitt
The Research and Scholarship Symposium
Glacial till (drift) prospecting has served a major role in corporate mineral exploration, especially for gold and diamond during the past 30 years. It involves analyzing heavy indicator minerals from bulk sampling of various glacial deposits in order to track up ice flow direction to the potential orebody (such as a kimberlite pipe or Cu-Ni deposit), a technique commonly used in Canada but not in the U.S. Heavy minerals including diamond, gold, and native copper have been found in Ohio glacial till; the provenance of these heavy minerals is the Precambrian bedrock north of Ohio. This study utilized standard ...
Early Miocene Antarctic Glacial History: New Insights From Heavy Mineral Analysis From Andrill And–2a Drill Core Sediments, 2015 University College London
Early Miocene Antarctic Glacial History: New Insights From Heavy Mineral Analysis From Andrill And–2a Drill Core Sediments, Francesco Iacoviello, Giovanna Giorgetti, Isabella Turbanti Memmi, Sandra Passchier
ANDRILL Research and Publications
The present study deals with heavy mineral analysis of late Early Miocene marine sediments recovered in the McMurdo Sound region (Ross Sea, Antarctica) during the ANDRILL— SMS Project in 2007. The main objective is to investigate how heavy mineral assemblages reflect different source rocks and hence different provenance areas. These data contribute to a better understanding of East Antarctica ice dynamics in the Ross Sea sector during the Early Miocene (17.6–20.2 Ma), a time of long-term global warming and sea level rise. The AND-2A drill core recovered several stratigraphic intervals that span from Early Miocene to Pleistocene ...
Glacier Slip And Seismicity Induced By Surface Melt, 2015 Iowa State University
Glacier Slip And Seismicity Induced By Surface Melt, Peter Lindsay Moore, J. Paul Winberry, Neal R. Iverson, Knut A. Christianson, Sridhar Anandakrishnan, Mark E. Mathison, Denis Cohen
Peter Lindsay Moore
Many of the key processes governing fast glacier flow involve interaction between a glacier and its basal hydrological system, which is hidden from direct observation. Passive seismic monitoring has shown promise as a tool for remotely monitoring basal processes, but lack of glacier-bed access prevents clear understanding of the relationships between subglacial processes and corresponding seismic emissions. Here we describe direct measurements of basal hydrology, sliding, and broadband seismicity made in a unique subglacial facility in Norway during the onset of two summer melt seasons. In the most pronounced of these episodes, rapid delivery of surface meltwater to the bed ...