A5074879666- Cryospheric studies and observations
- Geology and Paleoclimatology Research
- Planetary Science and Exploration
- Winter Sports Injuries and Performance
- Climate change and permafrost
- Arctic and Antarctic ice dynamics
- Landslides and related hazards
- Astro and Planetary Science
- Space Exploration and Technology
- Methane Hydrates and Related Phenomena
- Polar Research and Ecology
- Paleontology and Stratigraphy of Fossils
- Pleistocene-Era Hominins and Archaeology
- Geological formations and processes
- Climate variability and models
- Distributed and Parallel Computing Systems
- Geological Modeling and Analysis
- Tree-ring climate responses
- Meteorological Phenomena and Simulations
- Marine and environmental studies
- Computational Physics and Python Applications
- Geological Formations and Processes Exploration
- State Capitalism and Financial Governance
- Isotope Analysis in Ecology
- Atmospheric aerosols and clouds
University of Maine
2011-2024
University of Maine System
1991-2011
Columbia University
2007
University of Rhode Island
1984
Princeton University
1979
The final effort of the CLIMAP project was a study last interglaciation, time minimum ice volume some 122,000 yr ago coincident with Substage 5e oxygen isotopic minimum. Based on detailed isotope analyses and biotic census counts in 52 cores across world ocean, interglacial sea-surface temperatures (SST) were compared those today. There are small SST departures mid-latitude North Atlantic (warmer) Gulf Mexico (cooler). eastern boundary currents South Pacific oceans marked by large anomalies...
Abstract Ten ice-sheet models are used to study sensitivity of the Greenland and Antarctic ice sheets prescribed changes surface mass balance, sub-ice-shelf melting basal sliding. Results exhibit a large range in projected contributions sea-level change. In most cases, volume above flotation lost is linearly dependent on strength forcing. Combinations forcings can be closely approximated by summing from single forcing experiments, suggesting that nonlinear feedbacks modest. Our indicate more...
Abstract This paper discusses results from the second phase of European Ice Sheet Modelling Initiative (EISMINT). It reports intercomparison ten operational ice-sheet models and uses a series experiments to examine implications thermomechanical coupling for model behaviour. A schematic, circular ice sheet is used in work which investigates both steady states response stepped changes climate. The major finding that radial symmetry implied experimental design can, under certain circumstances,...
Abstract. The largest uncertainty in projections of future sea-level change results from the potentially changing dynamical ice discharge Antarctica. Basal ice-shelf melting induced by a warming ocean has been identified as major cause for additional flow across grounding line. Here we attempt to estimate range Antarctica combining climatic forcing, oceanic response and ice-sheet model response. global mean temperature increase is obtained historically constrained emulations with MAGICC-6.0...
Abstract Atmospheric, oceanic, and subglacial forcing scenarios from the Sea‐level Response to Ice Sheet Evolution (SeaRISE) project are applied six three‐dimensional thermomechanical ice‐sheet models assess Antarctic ice sheet sensitivity over a 500 year timescale inform future modeling field studies. Results indicate (i) growth with warming, except within low‐latitude basins (where inland thickening is outpaced by marginal thinning); (ii) mass loss enhanced sliding (with dominated high...
Optimized regional climate simulations are conducted using the Polar MM5, a version of fifth-generation Pennsylvania State University–NCAR Mesoscale Model (MM5), with 60-km horizontal resolution domain over North America during Last Glacial Maximum (LGM, 21 000 calendar years ago), when much continent was covered by Laurentide Ice Sheet (LIS). The objective is to describe LGM annual cycle at high spatial an emphasis on winter atmospheric circulation. Output from tailored NCAR Community...
Absorption of cosmic rays by atmospheric mass varies temporally due to a redistribution pressure ice sheets during glaciations, the compression and expansion atmosphere cooling warming, changes in katabatic winds near large masses. These processes can result production rates cosmogenic nuclides which, when integrated over long exposure durations may 0% >5% adjustments site depending on location. Combining CCM3 model with imbedded for 20 ka, we show that (relative today) are greatest at...
Abstract Preliminary results are presented on a solution of the two-dimensional time-dependent continuity equation for mass conservation governing ice-sheet dynamics. The is solved using column-averaged velocity to define horizontal flux in finite-element formulation. This yields map-plane model where flow directions, velocities, and surface elevations defined by bedrock topography, accumulation/ablation pattern, case initial configuration. alleviates flow-band limitation that direction be...
Abstract The Sea‐level Response to Ice Sheet Evolution (SeaRISE) effort explores the sensitivity of current generation ice sheet models external forcing gain insight into potential future contribution sea level from Greenland and Antarctic sheets. All participating simulated response three types forcings: a change in oceanic condition, warmer atmospheric environment, enhanced basal lubrication. Here an analysis spatial is presented, impact model physics spin‐up on projections explored....
Abstract. We here reconstruct the paleotopography of Northern Hemisphere ice sheets during glacial maxima marine isotope stages (MIS) 5b and 4.We employ a combined approach, blending geologically based reconstruction numerical modeling, to arrive at probable sheet extents topographies for each these two time slices. For physically 3-D calculation on derived 2-D constraints, we use University Maine Ice Sheet Model (UMISM) calculate thickness topography. The approach modeling strategy is...
A lateral moraine band on Mount Waesche, a volcanic nunatak in Marie Byrd Land, provides estimates of past ice sheet surface elevations West Antarctica. Helium-3 and chlorine-36 exposure ages indicate that the proximal part moraine, up to 45 meters above present surface, was deposited about 10,000 years ago, substantially later than maximum extent Ross Embayment. The upper distal may record multiple earlier high stands. nonequilibrium model predicts delay several thousand levels at Waesche...
Abstract The juxtaposition of wet‐based erosive ice in valleys and cold‐based, non‐erosive atop felsenmeer‐covered interfluve plateaus has generated relief the Torngat Mountains northeastern Canada. Measurements situ terrestrial cosmogenic nuclide (TCN) concentrations from 31 bedrock sites, coupled with soils geomorphology, indicate that erosion been >2 m during a single glacial–interglacial cycle. However, on summit long‐term (over several cycles) rate is <1·4 Ma −1 . TCN ratios...
The ∼166,000 km 2 fan‐shaped deposit at Arsia Mons contains three characteristic facies (ridged, knobby, and smooth), which are interpreted as the depositional remains of a cold‐based glacier that was present on west–northwestern flanks in Late Amazonian period Mars history. Here, we consider several high‐elevation graben western flank source regions for late‐stage, glaciers overflowed walls, advanced tens to hundreds kilometers downslope, experienced subsequent retreat, left distinctive...
The University of Maine Ice Sheet Model was used to study basal conditions during retreat the Laurentide ice sheet in Maine. Within 150 km margin, melt rates average ∼5 mm a −1 retreat. They decline over next 100 km, so areas frozen bed develop northern By integrating rate drainage area typically subtended by an esker, we obtained discharge at margin ~1.2 m 3 s -1 . While such could have moved material Katahdin it likely too low build esker time available. Additional water from glacier...
ICESat elevation profiles of tabular iceberg margins and the Ronne Ice Shelf edge reveal shapes indicative two types bending forces. Icebergs shelf fronts in sea‐ice‐covered areas have broad (∼1000 m wide), rounded, ∼0.6 high ‘berms’ outer edges that slope down several meters toward water. Bergs warmer water 2 to 5m ‘ramparts’ with ∼1500 wide edge‐parallel ‘moats’ inboard edge. This latter pattern was first revealed images from International Space Station (ISS) showing melt ponds on one just...
Abstract Regional climate simulations are conducted using the Polar fifth-generation Pennsylvania State University (PSU)–NCAR Mesoscale Model (MM5) with a 60-km horizontal resolution domain over North America to explore summer of Last Glacial Maximum (LGM: 21 000 calendar years ago), when much continent was covered by Laurentide Ice Sheet (LIS). Output from tailored NCAR Community Climate version 3 (CCM3) simulation LGM is used provide initial and lateral boundary conditions for MM5. include...
Abstract A finite-element solution of the time-dependent mass-continuity equation for column-averaged ice-sheet flow and sliding is applied to Antarctic ice sheet. First, a calibration model steady-state present configuration presented. With fitted values parameters describing regions sliding, degree bed coupling hardness, change in mean annual sea-level temperature used simulate variation climatic conditions over Antarctica both warming cooling climate. Paradoxically, climate up 9 deg leads...