A5068615759- Cryospheric studies and observations
- Geology and Paleoclimatology Research
- Climate change and permafrost
- Winter Sports Injuries and Performance
- Arctic and Antarctic ice dynamics
- Polar Research and Ecology
- Landslides and related hazards
- Methane Hydrates and Related Phenomena
- Climate variability and models
- Indigenous Studies and Ecology
- Seismic Waves and Analysis
- Per- and polyfluoroalkyl substances research
- Toxic Organic Pollutants Impact
- Geophysical Methods and Applications
- Geological Modeling and Analysis
- Planetary Science and Exploration
- Astro and Planetary Science
- Insect symbiosis and bacterial influences
- Soil erosion and sediment transport
- Dendrimers and Hyperbranched Polymers
- Aeolian processes and effects
- Outdoor and Experiential Education
- Geological formations and processes
- Soil Moisture and Remote Sensing
- Engineering Education and Pedagogy
University of Maine
2014-2024
Cold Regions Research and Engineering Laboratory
2012-2022
United States Army
2014-2022
United States Army Corps of Engineers
2012-2019
Colby College
2019
University of Washington
2017-2018
Earth and Space Research
2017-2018
U.S. Army Engineer Research and Development Center
2017-2018
United States Department of the Army
2015
Abstract FlyBase (flybase.org) is a model organism database and knowledge base about Drosophila melanogaster, commonly known as the fruit fly. Researchers from around world rely on genetic, genomic, functional information available in FlyBase, well its tools to view interrogate these data. In this article, we describe latest developments updates FlyBase. These include introduction of single-cell RNA sequencing data, improved content display information, updated orthology pipelines, new...
Abstract Future precipitation changes in a warming climate depend regionally upon the response of natural modes to anthropogenic forcing. North Pacific hydroclimate is dominated by Aleutian Low, semi-permanent wintertime feature characterized frequent low-pressure conditions that influenced tropical Ocean temperatures through Pacific-North American (PNA) teleconnection pattern. Instrumental records show recent increase coastal Alaskan and Low intensification, but are insufficient length...
Abstract Future changes in North Pacific wintertime climate will be largely determined by the response of Aleutian Low (ALow) pressure system to anthropogenic forcing. Although ALow has intensified over twentieth century, global model projections future variability are equivocal. In order evaluate decadal centennial forcing mechanisms and provide context for modern intensification, here we combine a new Denali ice core (Alaska) sea‐salt sodium record with Mount Logan (Yukon) develop...
Abstract. Widespread existing geological records from above the modern ice sheet surface and outboard of current margin show that Antarctic Ice Sheet (AIS) was much more extensive at Last Glacial Maximum (∼ 20 ka) than present. However, whether it ever smaller present during last few millennia, (if so) by how much, is known only for a locations because direct evidence lies within or beneath sheet, which challenging to access. Here, we describe retreat readvance (henceforth “readvance”) AIS...
Accurate identification of the relationships between permafrost extent and landscape patterns can help to develop airborne geophysical or remote sensing tools map in locations across large areas. These will be particularly applicable discontinuous where climate warming disturbances such as human development fire lead rapid degradation. We have linked field-based geophysical, point-scale, imagery surveying measurements at five scars (1930, 1975, 1988, 2001, 2010) on Tanana Flats central...
Abstract The rapidly retreating Thwaites and Pine Island glaciers together dominate present-day ice loss from the West Antarctic Ice Sheet are implicated in runaway deglaciation scenarios. Knowledge of whether these were substantially smaller mid-Holocene subsequently recovered to their present extents is important for assessing current recession irreversible. Here we reconstruct relative sea-level change radiocarbon-dated raised beaches at sites immediately seawards glaciers, allowing us...
Abstract. Cosmogenic-nuclide concentrations in subglacial bedrock cores show that the West Antarctic Ice Sheet (WAIS) at a site between Thwaites and Pope glaciers was least 35 m thinner than present past several thousand years then subsequently thickened. This is important because of concern thinning grounding line retreat these nearby Amundsen Sea Embayment may irreversibly lead to deglaciation significant portions WAIS, with decimeter- meter-scale sea level rise within decades centuries. A...
Abstract We review successes and challenges from five recent subglacial bedrock drilling campaigns intended to find evidence for Antarctic Ice Sheet retreat during warm periods in the geologic past. Insights into times when polar ice sheets were smaller than present serve as guiding information modeling efforts that aim predict rate magnitude of future sea level rise would accompany major Sheet. One method provide direct timing deglaciations minimum extent prior is extract cores cosmogenic...
Abstract. Unambiguous identification of past episodes ice sheet thinning below the modern surface and grounding line retreat inboard present requires recovery exposure dating subglacial bedrock. Such efforts are needed to understand significance potential future reversibility ongoing projected change in Antarctica. Here we evaluate suitability for bedrock drilling sites Hudson Mountains, which located Amundsen Sea sector West We use an model field data – geological observations,...
Anthropogenic nitrogen oxide (NOx = NO + NO2) emissions have increased since the Industrial Revolution as a result of fossil fuel burning, contributing to increasing atmospheric acidity and changes oxidative capacity atmosphere. Oxidation NOx leads formation nitrate both in gas phase (HNO3(g)) aerosol (p-NO3–), which may then be removed from atmosphere via wet dry deposition. Ice core records thus used infer past concentrations given high enough accumulation rates prevent...
Terrestrial meteorite ages indicate that some ice at the Allan Hills blue area (AH BIA) may be as old 2.2 Ma. As such, from AH BIA could potentially used to extend core record of paleoclimate beyond 800 ka. We collected samples 5 10 cm depth along a km transect through main icefield and drilled 225 m (S27) midpoint develop climate archive BIA. Stable water isotope measurements (δD) surface chips S27 yield comparable signals, indicating has not been significantly altered in ice. Measurements...
We describe glacial-geological observations and cosmogenic-nuclide exposure ages from the Schmidt, Williams, Thomas Hills in Pensacola Mountains of Antarctica adjacent to Foundation Ice Stream (FIS). Our aim is learn about changes thickness grounding line position Antarctic Sheet Weddell Sea embayment between Last Glacial Maximum (LGM) present. Glacial-geological all three regions indicate that currently-ice-free areas were covered by ice during one or more past sheet expansions, this was...
The distribution of shallow frozen ground is paramount to research in cold regions, and subject temporal spatial changes influenced by climate, landscape disturbance ecosystem succession. Remote sensing from airborne satellite platforms increasing our understanding landscape-scale permafrost distribution, but typically lacks the resolution characterise finer-scale processes phenomena, which are better captured integrated surface geophysical methods. Here, we demonstrate use electrical...
Installations built on ice, permafrost, or seasonal frozen ground require careful design to avoid melting issues. Therefore, efforts rebuild McMurdo Station, Antarctica, improve operational efficiency and consolidate energy resources knowledge of near-surface geology. Both 200 400 MHz ground-penetrating radar (GPR) data were collected in during January, October, November 2015 detect the active layer, excess fill thickness, solid bedrock depth, buried utilities construction waste debris. Our...
Abstract Warming in high‐elevation regions has societally important impacts on glacier mass balance, water resources, and sensitive alpine ecosystems, yet very few temperature records exist from the middle or high latitudes. While a variety of paleoproxy provide critical low elevations over recent centuries, melt layers preserved glaciers present an opportunity to develop calibrated, annually resolved elevations. Here we 400‐year proxy record based layer stratigraphy two ice cores collected...
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 which reached bed, from flank Jarvis Glacier, eastern Alaska Range, Alaska. The core sites lie ~1 km downstream source, with abundant water present in extracted cores and at base glacier. All exhibit dipping layers, combination debris bands bubble-free domains. Grain sizes coarsen average...
Abstract The current ice core record extends back 800,000 years. Geologic and glaciological evidence suggests that the Allan Hills Blue Ice Area, East Antarctica, may preserve a continuous further in time. In this study, we use ice‐penetrating radar existing age constraints to map internal stratigraphy structure of Main Field. dated isochrones provide for an flow model estimate near bed. Previous drilling region recovered stratigraphically disturbed sections up 2.7 million years old. Our...
Abstract We reanalyzed mass balance records at Taku and Lemon Creek Glaciers to better understand the relative roles of hypsometry, local climate dynamics as drivers. Over 1946–2018 period, cumulative balances diverged. Tidewater Glacier advanced gained an average rate +0.25 ± 0.28 m w.e. a –1 , contrasting with retreat loss −0.60 0.15 −1 land-terminating Glacier. The uniform influence regional is demonstrated by strong correlations among annual data. Regional warming trends forced similar...
Abstract Streaming ice accounts for a major fraction of global flux, yet we cannot fully explain the dominant controls on its kinematics. In this contribution, use an anisotropic full-Stokes thermomechanical flow solver to characterize how mechanical anisotropy and temperature distribution affect flux. For stream glacier geometries explored, found that flux increases 1–3% per °C increase in margin. Glaciers streams with crystallographic fabric oriented approximately normal shear plane by...
Abstract We collected ground‐penetrating radar (GPR) and frequency‐domain electromagnetic induction (FDEM) profiles in 2011 2012 to identify the extent of permafrost relative surface biomass solar insolation around Twelvemile Lake near Fort Yukon, Alaska. compared a Landsat‐derived estimate modeled from digital elevation model geophysical measurements. show correspondence between vegetation type seasonal freeze–thaw. Thicker (≥25 m) was covered by greater biomass, thaw depths these regions...
Abstract Pine Island Glacier, West Antarctica, is the largest Antarctic contributor to global sea-level rise and vulnerable rapid retreat, yet our knowledge of its deglacial history since Last Glacial Maximum based largely on marine sediments that record a retreat ending in early Holocene. Using suite 10Be exposure ages from onshore glacial deposits directly adjacent we show this major glacier thinned rapidly mid-Holocene. Our results indicate Glacier was at least 690 m thicker than present...
ABSTRACT We collected ~1300 km of ground-penetrating radar profiles over McMurdo Ice Shelf, Antarctica, using frequencies between 40 and 400 MHz to determine extent, continuity depth the brine. also used meteoric ice thickness locate englacial features, which may suggest shelf instability. The brine extends 9–13 inland from terminus covers entire region Ross, White Black Islands. Jump unconformities basal fractures exist in shelf, respectively, suggesting prior fracturing re-suturing. One...
Links between climate and glacier surges are poorly understood but required to enable prediction of mitigation associated hazards. Here, we investigate the role snow accumulation, rain, temperature on surge periodicity, area changes, timing initiation since 1930s at Donjek Glacier, Yukon, Canada. Snow accumulation measured in three ice cores collected Eclipse Icefield indicates that a cumulative 15.5 ± 1.46 or 16.6 2.0 m w.e. occurred ten twelve years each its last eight surges, depending...
Abstract Globally, mountain glaciers and ice caps are losing dramatic volumes of ice. The resultant sea‐level rise is dominated by contributions from Alaska. Plateau icefields may be especially sensitive to climate change due the non‐linear controls their topography imparts on response change. However, Alaskan plateau have been subject little structural glaciological or regional geomorphological assessment, which makes present former mass balance difficult ascertain. We inventoried 1050 368...
Abstract We used measurements of radar-detected stratigraphy, surface ice-flow velocities and accumulation rates to investigate relationships between local valley-glacier regional ice-sheet dynamics in around the Schmidt Hills, Pensacola Mountains, Antarctica. Ground-penetrating radar profiles were collected perpendicular long axis Hills margin Foundation Ice Stream (FIS). Within valley confines, glacier consists blue ice, show internal stratigraphy dipping steeply toward nunataks truncated...