Application of GPR to the Delineation of Melt Regimes, Internal Stratigraphy, and Flow Dynamics at Three Potential Ice Core Drill Sites in the Alaska Range

2011 ◽  
Author(s):  
Seth Campbell ◽  
Karl Kreutz ◽  
Erich Osterberg ◽  
Steven Arcone ◽  
Cameron Wake
Keyword(s):  
Ice Core ◽  
Flow Dynamics ◽  
Alaska Range

scholarly journals Melt regimes, stratigraphy, flow dynamics and glaciochemistry of three glaciers in the Alaska Range

2012 ◽  
Vol 58 (207) ◽  
pp. 99-109 ◽  
Author(s):  
Seth Campbell ◽  
Karl Kreutz ◽  
Erich Osterberg ◽  
Steven Arcone ◽  
Cameron Wake ◽  
...  
Keyword(s):  
Ground Penetrating Radar ◽  
Ice Core ◽  
Chemical Diffusion ◽  
Flow Dynamics ◽  
Alaska Range ◽  
Ice Volume ◽  
Glacier Ice ◽  
Age Model ◽  
Ground Penetrating ◽  
Climate Studies

AbstractWe used ground-penetrating radar (GPR), GPS and glaciochemistry to evaluate melt regimes and ice depths, important variables for mass-balance and ice-volume studies, of Upper Yentna Glacier, Upper Kahiltna Glacier and the Mount Hunter ice divide, Alaska. We show the wet, percolation and dry snow zones located below ~2700ma.s.l., at ~2700 to 3900ma.s.l. and above 3900ma.s.l., respectively. We successfully imaged glacier ice depths upwards of 480 m using 40-100 MHz GPR frequencies. This depth is nearly double previous depth measurements reached using mid-frequency GPR systems on temperate glaciers. Few Holocene-length climate records are available in Alaska, hence we also assess stratigraphy and flow dynamics at each study site as a potential ice-core location. Ice layers in shallow firn cores and attenuated glaciochemical signals or lacking strata in GPR profiles collected on Upper Yentna Glacier suggest that regions below 2800ma.s.l. are inappropriate for paleoclimate studies because of chemical diffusion, through melt. Flow complexities on Kahiltna Glacier preclude ice-core climate studies. Minimal signs of melt or deformation, and depth-age model estimates suggesting ~4815 years of ice on the Mount Hunter ice divide (3912ma.s.l.) make it a suitable Holocene-age ice-core location.

scholarly journals Reconstruction of recent climate change in Alaska from the Aurora Peak ice core, central Alaska

2015 ◽  
Vol 11 (2) ◽  
pp. 217-226 ◽  
Author(s):  
A. Tsushima ◽  
S. Matoba ◽  
T. Shiraiwa ◽  
S. Okamoto ◽  
H. Sasaki ◽  
...  
Keyword(s):  
Climate Change ◽  
Accumulation Rate ◽  
Ice Core ◽  
Chemical Species ◽  
Volcanic Eruptions ◽  
Gulf Of Alaska ◽  
Temporal Variations ◽  
Storm Activity ◽  
Alaska Range ◽  
Recent Climate

Abstract. A 180.17 m ice core was drilled at Aurora Peak in the central part of the Alaska Range, Alaska, in 2008 to allow reconstruction of centennial-scale climate change in the northern North Pacific. The 10 m depth temperature in the borehole was −2.2 °C, which corresponded to the annual mean air temperature at the drilling site. In this ice core, there were many melt–refreeze layers due to high temperature and/or strong insolation during summer seasons. We analyzed stable hydrogen isotopes (δD) and chemical species in the ice core. The ice core age was determined by annual counts of δD and seasonal cycles of Na+, and we used reference horizons of tritium peaks in 1963 and 1964, major volcanic eruptions of Mount Spurr in 1992 and Mount Katmai in 1912, and a large forest fire in 2004 as age controls. Here, we show that the chronology of the Aurora Peak ice core from 95.61 m to the top corresponds to the period from 1900 to the summer season of 2008, with a dating error of ± 3 years. We estimated that the mean accumulation rate from 1997 to 2007 (except for 2004) was 2.04 m w.eq. yr-1. Our results suggest that temporal variations in δD and annual accumulation rates are strongly related to shifts in the Pacific Decadal Oscillation index (PDOI). The remarkable increase in annual precipitation since the 1970s has likely been the result of enhanced storm activity associated with shifts in the PDOI during winter in the Gulf of Alaska.

scholarly journals A 400‐Year Ice Core Melt Layer Record of Summertime Warming in the Alaska Range

2018 ◽  
Vol 123 (7) ◽  
pp. 3594-3611 ◽  
Author(s):  
Dominic Winski ◽  
Erich Osterberg ◽  
Karl Kreutz ◽  
Cameron Wake ◽  
David Ferris ◽  
...  
Keyword(s):  
Ice Core ◽  
Alaska Range

scholarly journals Aerogeophysical characterization of Titan Dome, East Antarctica, and potential as an ice core target

2021 ◽  
Vol 15 (4) ◽  
pp. 1719-1730
Author(s):  
Lucas H. Beem ◽  
Duncan A. Young ◽  
Jamin S. Greenbaum ◽  
Donald D. Blankenship ◽  
Marie G. P. Cavitte ◽  
...  
Keyword(s):  
Ice Core ◽  
Flow Dynamics ◽  
Ice Age ◽  
Middle Pleistocene ◽  
Laser Altimetry ◽  
Basal Ice ◽  
Core Site ◽  
Middle Pleistocene Transition ◽  
Fast Flow

Abstract. Based on sparse data, Titan Dome has been identified as having a higher probability of containing ice that would capture the middle Pleistocene transition (1.25 to 0.7 Ma). New aerogeophysical observations (radar and laser altimetry) collected over Titan Dome, located about 200 km from the South Pole within the East Antarctic Ice Sheet, were used to characterize the region (e.g., geometry, internal structure, bed reflectivity, and flow history) and assess its suitability as a paleoclimate ice core site. The radar coupled with an available ice core chronology enabled the tracing of dated internal reflecting horizons throughout the region, which also served as constraints on basal ice age modeling. The results of the survey revealed new basal topographic detail and better constrain the ice topographical location of Titan Dome, which differs between community datasets. Titan Dome is not expected to be relevant to the study of the middle Pleistocene transition due to a combination of past fast flow dynamics, the basal ice likely being too young, and the temporal resolution likely being too coarse if 1 Ma ice were to exist.

scholarly journals Reconstruction of recent climate change in Alaska from the Aurora Peak ice core, central Alaska

2014 ◽  
Vol 10 (2) ◽  
pp. 1421-1446 ◽  
Author(s):  
A. Tsushima ◽  
S. Matoba ◽  
T. Shiraiwa ◽  
S. Okamoto ◽  
H. Sasaki ◽  
...  
Keyword(s):  
Climate Change ◽  
Accumulation Rate ◽  
Ice Core ◽  
Chemical Species ◽  
Volcanic Eruptions ◽  
Gulf Of Alaska ◽  
Storm Activity ◽  
Alaska Range ◽  
Recent Climate ◽  
Drilling Site

Abstract. A 180.17 m ice core was drilled at Aurora Peak in the central part of the Alaska Range, Alaska, in 2008 to allow reconstruction of centennial-scale climate change in the northern North Pacific. The 10 m-depth temperature in the borehole was −2.2 °C, which corresponded to annual mean air temperature at the drilling site. In this ice core, there were many melt-refrozen layers due to high temperature and/or strong insolation during summer seasons. We analyzed stable hydrogen isotopes (δD) and chemical species in the ice core. The ice core age was determined by annual counts of δD and seasonal cycles of Na+, and we used reference horizons of tritium peaks in 1963 and 1964, major volcanic eruptions of Mount Spurr in 1992 and Mount Katmai in 1912, and a large forest fire in 2004 as age controls. Here, we show that the chronology of the Aurora Peak ice core from 95.61 m w.eq. to the top corresponds to the period from 1900 to the summer season of 2008, with a dating error of ±3 years. We estimated that the mean accumulation rate from 1997 to 2007 (except for 2004) was 1.88 m w.eq per year. Our results suggest that temporal variation in δD and annual accumulation rates are strongly related to shifts in the Pacific Decadal Oscillation index (PDOI). The remarkable increase in annual precipitation since the 1970s has likely been the result of enhanced storm activity associated with shifts in the PDOI during winter in the Gulf of Alaska.

scholarly journals Organochlorine Pollutants within a Polythermal Glacier in the Interior Eastern Alaska Range

2018 ◽  
Author(s):  
Kimberley R. Miner ◽  
Seth Campbell ◽  
Christopher Gerbi ◽  
Anna Lilijedahl ◽  
Therese Anderson ◽  
...  
Keyword(s):  
Atmospheric Transport ◽  
Ice Core ◽  
Alaska Range ◽  
Near Surface ◽  
Glacial Meltwater ◽  
Organochlorine Pollutants ◽  
Core Samples ◽  
Interior Alaska ◽  
Polythermal Glacier ◽  
Surface Ice

To assess the presence of organochlorine pollutants (OCP) in Alaskan sub-Arctic latitudes, we analyzed ice core and meltwater samples from Jarvis Glacier, a polythermal glacier in Interior Alaska. Jarvis Glacier is receding as atmospheric warming continues throughout the region, increasing opportunity for OCP transport both englacially and into the proglacial watershed. Across all meltwater and ice core samples we identify the pesticides DDT, DDE and DDD, α- HCH and ϒ-HCH. OCP concentrations in ice core samples were highest at the 7-14 m depth (0.51 ng/L of DDT) and decreased gradually approaching the bedrock at 79m. Meltwater concentrations from the proglacial creek slightly exceeded concentrations found in the ice core, potentially indicating aggregate OCP glacial loss, with peak OCP concentration (1.12 ng/L of DDD) taken in July and potentially associated to peak melt. Ongoing use of DDT to fight Malaria in Asia, and the extended atmospheric range of HCH may account for concentrations in near-surface ice, correlating with use and atmospheric transport. The opportunity for biota bioaccumulation of OCPs, or human uptake of OCPs from glacial meltwater, may increase as glacial melt continues.

scholarly journals Microstructures in a shear margin: Jarvis Glacier, Alaska

2021 ◽  
pp. 1-14
Author(s):  
Christopher Gerbi ◽  
Stephanie Mills ◽  
Renée Clavette ◽  
Seth Campbell ◽  
Steven Bernsen ◽  
...  
Keyword(s):  
Flow Dynamics ◽  
Mechanical Anisotropy ◽  
Lateral Margin ◽  
Natural Setting ◽  
Alaska Range ◽  
The Core ◽  
Grain Sizes ◽  
Strong Control ◽  
Crystallographic Orientations

Abstract Microstructures, including crystallographic fabric, within the margin of streaming ice can exert strong control on flow dynamics. To characterize a natural setting, we retrieved three cores, two of which reached bed, from the flank of Jarvis Glacier, eastern Alaska Range, Alaska. The core sites lie ~1 km downstream of the source, with abundant water present in the extracted cores and at the base of the glacier. All cores exhibit dipping layers, a combination of debris bands and bubble-free domains. Grain sizes coarsen on average approaching the lateral margin. Crystallographic orientations are more clustered and with c-axes closer to horizontal nearer the lateral margin. The measured fabric is sufficiently weak to induce little mechanical anisotropy, but the data suggest that despite the challenging conditions of warm ice, abundant water and a short flow distance, many aspects of the microstructure, including measurable crystallographic fabric, evolved in systematic ways.

scholarly journals Alpine ice-core drilling in the North Pacific region

2014 ◽  
Vol 55 (68) ◽  
pp. 83-87 ◽  
Author(s):  
Sumito Matoba ◽  
Kunio Shimbori ◽  
Takayuki Shiraiwa
Keyword(s):  
North Pacific ◽  
Ice Core ◽  
Ice Cores ◽  
Kamchatka Peninsula ◽  
Pacific Region ◽  
Alaska Range ◽  
Core Drilling ◽  
The North ◽  
Summit Caldera ◽  
North Pacific Region

AbstractThe Institute of Low Temperature Science at Hokkaido University conducted ice-core drilling in alpine glaciers in the northern North Pacific region to reconstruct climate change in this region for the past few hundred years. We drilled two ice cores in the Kamchatka Peninsula, Russia. An ice core with a length of 211 m was drilled on a glacier at the summit caldera of Ushkovsky mountain in 1998. A second core, with a length of 115m (until bedrock was reached), was drilled on a glacier at the summit caldera of Ichinsky mountain in 2006. We drilled three further ice cores in Alaska, USA. Two ice cores with lengths of 50 and 212m were drilled on a glacier at the summit caldera of Mount Wrangell in 2003 and 2004. The third ice core was drilled on the ice divide among three glaciers, Black Rapids, Trident and Susitna glaciers, which represent a flat saddle north of Aurora Peak in the Alaska Range. This paper details the field operations and characteristics of the different ice-drilling systems used and the problems encountered.

The role of the sinuses of valsalva in aortic root flow dynamics and aortic root surgery

2007 ◽  
Vol 55 (S 1) ◽  
Author(s):  
F Schoenhoff ◽  
C Loupatatzis ◽  
FS Eckstein ◽  
C Stoupis ◽  
FF Immer ◽  
...  
Keyword(s):  
Aortic Root ◽  
Flow Dynamics ◽  
Aortic Root Surgery
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