A5047864816- Cryospheric studies and observations
- Winter Sports Injuries and Performance
- Geology and Paleoclimatology Research
- Climate change and permafrost
- Arctic and Antarctic ice dynamics
- Landslides and related hazards
- Methane Hydrates and Related Phenomena
- Polar Research and Ecology
- Climate variability and models
- Atmospheric and Environmental Gas Dynamics
- Atmospheric chemistry and aerosols
- Geological Studies and Exploration
- Marine and coastal ecosystems
- Hydrocarbon exploration and reservoir analysis
- Seismic Waves and Analysis
- Maritime Navigation and Safety
- Tree-ring climate responses
- Underwater Vehicles and Communication Systems
- Pleistocene-Era Hominins and Archaeology
- Per- and polyfluoroalkyl substances research
- Atmospheric aerosols and clouds
- Flood Risk Assessment and Management
- Meteorological Phenomena and Simulations
- Rock Mechanics and Modeling
- Carbon Dioxide Capture Technologies
Woods Hole Oceanographic Institution
2016-2025
American Geophysical Union
2013
Pennsylvania State University
2002-2009
University of Washington
2008
Johns Hopkins University Applied Physics Laboratory
2008
Newcastle University
2008
The Ohio State University
2008
Earth System Science Interdisciplinary Center
2002
Cornell University
1996
Surface meltwater that reaches the base of an ice sheet creates a mechanism for rapid response flow to climate change. The process whereby such pathway is created through thick, cold has not, however, been previously observed. We describe (<2 hours) drainage large supraglacial lake down 980 meters bed Greenland Ice Sheet initiated by water-driven fracture propagation evolving into moulin flow. Drainage coincided with increased seismicity, transient acceleration, ice-sheet uplift, and...
It has been widely hypothesized that a warmer climate in Greenland would increase the volume of lubricating surface meltwater reaching ice-bedrock interface, accelerating ice flow and increasing mass loss. We have assembled data set provides synoptic-scale view, spanning ice-sheet to outlet-glacier flow, with which evaluate this hypothesis. On sheet, these reveal summer speedups (50 100%) consistent with, but somewhat larger than, earlier observations. The relative speedup outlet glaciers,...
Abstract. We present multi-model global datasets of nitrogen and sulfate deposition covering time periods from 1850 to 2100, calculated within the Atmospheric Chemistry Climate Model Intercomparison Project (ACCMIP). The computed fluxes are compared surface wet ice core measurements. use a new dataset for 2000–2002 based on critical assessment quality existing regional network data. show that day (year 2000 ACCMIP slice), results perform similarly previously published assessments. For this...
Abstract This study generates novel satellite‐derived estimates of Antarctic‐wide annual (1999–2009) surface meltwater production using an empirical relationship between radar backscatter from the QuikSCAT (QSCAT) satellite and melt calculated in situ energy balance observations. The resulting QSCAT‐derived fluxes significantly agree with output regional climate model RACMO2.1 independent ground‐based high‐resolution (4.45 km) QSCAT‐based uniquely detect interannually persistent intense...
Abstract We use an airborne‐radar method, verified with ice‐core accumulation records, to determine the spatiotemporal variations of snow over Thwaites Glacier, West Antarctica between 1980 and 2009. also present a regional evaluation modeled in Antarctica. Comparisons radar‐derived measurements model outputs show that three global models capture interannual variability well ( r > 0.9), but high‐resolution (RACMO2) has better absolute accuracy captures observed spatial = 0.86). Neither...
Water‐filled cracks are an effective mechanism to drive hydro‐fractures through thick ice sheets. Crack geometry is therefore critical in assessing whether a supraglacial lake contains sufficient volume of water keep crack water‐filled until it reaches the bed. In this study, we investigate fracture propagation using linear elastic mechanics model calculate dimensions beneath lakes. We find that cross‐sectional area increases non‐linearly with sheet thickness. Using these results, place...
Abstract Moulins are important conduits for surface meltwater to reach the bed of Greenland Ice Sheet. It has been proposed that in a warming climate, newly formed moulins associated with inland migration supraglacial lakes could introduce melt new regions bed, introducing or enhancing sliding there. By examining strain rates, we found upper limit where crevasses, and therefore moulins, likely form is ~1600 m. This also roughly elevation above which do not drain completely. Thus, this will...
Abstract. In Antarctica, uncertainties in mass input and output translate directly into uncertainty glacier balance thus sea level impact. While remotely sensed observations of ice velocity thickness over the major outlet glaciers have improved our understanding loss to ocean, snow accumulation vast Antarctic interior remains largely unmeasured. Here, we show that an airborne radar system, combined with ice-core glaciochemical analysis, provide means necessary measure rate at catchment-scale...
Antarctic ice sheet surface melting can regionally influence shelf stability, mass balance, and glacier dynamics, in addition to modulating near‐surface physical chemical properties over wide areas. Here, we investigate variability from 1999 2009 using radar backscatter time series the SeaWinds scatterometer aboard QuikSCAT satellite. These daily, continent‐wide observations are explored concert with situ meteorological records validate a threshold‐based melt detection method. Radar...
Abstract. Observed changes in the surface elevation of Greenland Ice Sheet are caused by ice dynamics, basal change, melt, mass balance (SMB) variability, and compaction overlying firn. The last two contributions quantified here using a firn model that includes compaction, meltwater percolation, refreezing. is forced with fluxes temperature from regional climate for period 1960–2014. results agree observations density, density profiles 62 cores, altimetric regions where ice-dynamical height...
Abstract Recent acceleration of Greenland's ocean‐terminating glaciers has substantially amplified the ice sheet's contribution to global sea level. Increased oceanic melting these tidewater is widely cited as likely trigger, and thought be highest within vigorous plumes driven by freshwater drainage from beneath glaciers. Yet larger part calving fronts outside remains largely unstudied. Here we combine ocean observations collected 100 m a glacier with numerical model show that unlike...
Interior Antarctica is among the most remote places on Earth and was thought to be beyond reach of human impacts when Amundsen Scott raced South Pole in 1911. Here we show detailed measurements from an extensive array 16 ice cores quantifying substantial toxic heavy metal lead pollution at throughout by 1889 – beating polar explorers more than 22 years. Unlike Arctic where peaked 1970s, as high early 20th century any time since industrialization. The similar timing magnitude changes...
Discharge of surface-derived meltwater at the submerged base Greenland's marine-terminating glaciers creates subglacial discharge plumes that rise along glacier/ocean interface. These impact submarine melting, calving, and fjord circulation. Observations plume properties dynamics are challenging due to their proximity calving edge glaciers. Therefore, date information on these has been largely derived from models. Here we present temperature, salinity, velocity data collected in a surfaced...
Earlier observations indicated that Whillans Ice Stream slowed from 1973 to 1997. We collected new GPS of the ice stream's speed in 2003 and 2004. These data show stream is continuing decelerate at rates about 0.6%/yr 2 , with faster near grounding line. Our also indicate deceleration extends over full width plain. Extrapolation trend suggests could stagnate sometime between middle 21st 22nd Centuries.
A new melt layer history from Siple Dome, West Antarctica, indicates notable late‐Holocene summertime warming. Visual stratigraphic analyses of the 1004‐m ice core identified 62 years with layers. Melting events began around 11.7 ka, followed by a period no melting 8.8–6.6 ka. Melt frequency increased 6.6 ka to present, 1000‐year‐average reaching maximum 2% at 0.8 We use our millennial‐scale archive as unique seasonal paleothermometer elucidate changes in Antarctic Holocene summer climate....
Abstract. Supraglacial lakes play an important role in establishing hydrological connections that allow lubricating seasonal meltwater to reach the base of Greenland Ice Sheet. Here we use new surface velocity observations examine influence supraglacial lake drainages and melt rate on ice flow. We find large, spatially extensive speedups concurrent with times drainage, showing a key modulating regional While is supplied bed via geographically sparse network moulins, observed ice-flow...