A5024845084- Cryospheric studies and observations
- Arctic and Antarctic ice dynamics
- Climate change and permafrost
- Winter Sports Injuries and Performance
- Landslides and related hazards
- Soil Geostatistics and Mapping
- Geology and Paleoclimatology Research
- Methane Hydrates and Related Phenomena
- Geochemistry and Geologic Mapping
- Atmospheric and Environmental Gas Dynamics
- Remote Sensing and LiDAR Applications
- Polar Research and Ecology
- Atmospheric aerosols and clouds
- Geographic Information Systems Studies
- Geological Modeling and Analysis
- Icing and De-icing Technologies
- Geophysics and Gravity Measurements
- Meteorological Phenomena and Simulations
- Geological Studies and Exploration
- Underwater Acoustics Research
- Geological formations and processes
- Calibration and Measurement Techniques
- Advanced Computational Techniques and Applications
- Oceanographic and Atmospheric Processes
- Hydrocarbon exploration and reservoir analysis
University of Colorado Boulder
2016-2025
Applied Mathematics (United States)
2024
University of Colorado System
2006-2024
NASA Research Park
2024
Goddard Space Flight Center
2024
University of Maryland, College Park
2021-2022
Cooperative Institute for Research in Environmental Sciences
2008-2020
Universität Trier
1996-2004
Institute of Arctic and Alpine Research
1994-2003
Scripps Institution of Oceanography
1989-1995
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...
NASA's Ice, Cloud and Land Elevation Satellite-II (ICESat-2) mission is a decadal survey (2016 launch). The objectives are to measure land ice elevation, sea freeboard, changes in these variables, as well collect measurements over vegetation facilitate canopy height determination. Two innovative components will characterize the ICESat-2 lidar: 1) collection of elevation data by multibeam system 2) application micropulse lidar (photon-counting) technology. A photon-counting altimeter yields...
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...
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....
NASA's Ice, Cloud and land Elevation Satellite ICESat-2, launched September 15, 2018, carries the first space-borne multi-beam micro-pulse photon-counting laser altimeter system, Advanced Topographic Laser Altimeter System (ATLAS). Observations from ATLAS are acquired in three pairs of weak strong beams with 0.7 m nominal along-track spacing (under clear-sky conditions). The recording observations as a photon point cloud, which includes signal background/noise events, requires dedicated...
Glacial acceleration is a main source of uncertainty in sea-level-change assessment. Measurement ice-surface heights with spatial and temporal resolution that not only allows elevation-change calculation, but also captures morphology its changes required to aid investigations the geophysical processes associated glacial acceleration. The Advanced Topographic Laser Altimeter System aboard NASA's future ICESat-2 Mission (launch 2017) will implement multibeam micropulse photon-counting lidar...
A suite of sensors has been assembled to map surface elevation and topography with fine resolution from small unmanned aircraft systems. The sensor package consists a light detecting ranging (LIDAR) instrument, an inertial measurement unit (IMU), Global Positioning System (GPS) module, digital still video cameras. system utilized ice sheet in Greenland measure sea freeboard roughness Fram Strait off the coast Svalbard Southern Ocean near McMurdo, Antarctica. accuracy is found be <; 10 cm...
Abstract The Advanced Topographic Laser Altimeter System (ATLAS) was launched aboard the Ice Cloud and land‐Elevation Satellite‐2 (ICESat‐2) satellite in September 2018. ATLAS is a single wavelength (532 nm) lidar system designed to acquire high resolution measurements of earth's surface while also obtaining atmospheric backscatter from molecules, clouds, aerosols. Because optimized for altimetry, data acquired unique many respects requires non‐standard analysis techniques. For example,...
As climate warms and the transition from a perennial to seasonal Arctic sea-ice cover is imminent, understanding melt ponding central changes in new Arctic. NASA's Ice, Cloud land Elevation Satellite (ICESat-2) has capacity provide measurements monitoring of onset on progression. Yet ponds are currently not identified ICESat-2 standard products, which only single surface determined. The objective this paper introduce mathematical algorithm that facilitates automated detection ATLAS data,...
Abstract Tenuous atmospheric layers, such as high, thin cirrus clouds and blowing snow over Antarctica, play an important role in the climate system, affecting energy fluxes between Earth atmosphere. Our knowledge of structure atmosphere is largely derived from satellite measurements. Yet tenuous layers can be hard to detect lidar data, especially daylight data characterized by high solar background. In this study, we introduce approach measurements NASA's ICESat‐2. The density‐dimension...
Since the 2018 launch of NASA's ICESat-2 mission, one capability its Advanced Topographic Laser Altimeter System (ATLAS) that has far exceeded expectations is bathymetric measurement. Although was designed to generate surface-specific along-track and gridded data products, bathymetry not a pre-launch science requirement mission. However, since launch, ATLAS proven capable measurement >40m in very clear waters [1], being used growing number disciplines. Post-launch efforts have focused on...
Abstract. We investigate sea ice conditions during the 2020 melt season, when warm air temperature anomalies in spring led to early onset, an extended and second-lowest September minimum Arctic extent observed. focus on region of most persistent cover examine pond depth retrieved from Ice, Cloud, land Elevation Satellite-2 (ICESat-2) using two distinct algorithms concert with a time series fraction concentration derived Sentinel-2 imagery obtain insights about melting surface three...
Abstract The primary goal of the Western Arctic Linkage Experiment (WALE) was to better understand uncertainties simulated hydrologic and ecosystem dynamics western in context 1) data available drive models 2) different approaches simulating regional hydrology dynamics. Analyses datasets on climate for driving within during late twentieth century indicate that there are substantial differences among mean states temperature, precipitation, vapor pressure, radiation variables. Among studies...
Abstract The dynamic/thermodynamic shallow-ice model SICOPOLIS is applied to the Greenland ice sheet. Paleoclimatic spin-ups from 125 ka BP until today, as well future-climate experiments 500 years into future, are carried out with three different grid spacings, namely 20, 10 and 5 km. scenarios a subset of those specified by SeaRISE (Sea-level Response Ice Sheet Evolution) community effort. bed topography includes improved troughs for Jakobshavn Isbræ, Helheim, Kangerdlugssuaq Petermann...
Summary Geodetical least-squares prediction and collocation, geophysical inverse theory, geostatistics (the theory of regionalized variables) provide methods that from a theoretical point view solve common problem: continuously defined spatial model is supported by only finitely many observations. The synopsis focuses on methodological aspects as well differences in the underlying mathematical assumptions their geological implications. Introductory examples familiarize with approaches...
The topic of this paper is the airborne evaluation ICESat-2 Advanced Topographic Laser Altimeter System (ATLAS) measurement capabilities and surface-height-determination over crevassed glacial terrain, with a focus on geodetical accuracy geophysical data collected from helicopter. To obtain surface heights otherwise complex ice surface, are analyzed using density-dimension algorithm for surfaces (DDA-ice), which yields at nominal 0.7 m along-track spacing ATLAS data. As result an ongoing...
Abstract In most glaciological and hydrological models, surface roughness of snow ice is an important parameter. However, generally used only as estimated parameter for lack available observations. this paper, we present a method to collect analyze ice-surface-roughness data using specially designed instrument survey geostatistical methods analysis. The glacier-roughness sensor (GRS), built at the University Trier, records variations in microtopography 0.2 m × 0.1 resolution when pulled...
The potential of satellite radar altimetry for high-resolution mapping Antarctic ice streams is evaluated, using retracked and slope-corrected data from the Lambert Glacier Amery Ice Shelf area, East Antarctica, acquired by Geosat during Exact Repeat Mission (ERM), 1986–89. map area includes lower north 72.18°S, southern Shelf, grounded inland sheet on both sides. ERM found to provide substantially more complete coverage than 1978 Seasat altimetry, due improved tracking. Variogram methods...