A5066249334- Cryospheric studies and observations
- Winter Sports Injuries and Performance
- Arctic and Antarctic ice dynamics
- Landslides and related hazards
- Climate change and permafrost
- Geology and Paleoclimatology Research
- Atmospheric and Environmental Gas Dynamics
- Polar Research and Ecology
- Climate variability and models
- Methane Hydrates and Related Phenomena
- Meteorological Phenomena and Simulations
- Geophysics and Gravity Measurements
- Soil Moisture and Remote Sensing
- Advanced Chemical Sensor Technologies
- Gamma-ray bursts and supernovae
- Remote Sensing and LiDAR Applications
- 3D Surveying and Cultural Heritage
- Planetary Science and Exploration
- Ionosphere and magnetosphere dynamics
- Optical measurement and interference techniques
- Wildlife-Road Interactions and Conservation
- Atmospheric aerosols and clouds
- Oceanographic and Atmospheric Processes
- High Altitude and Hypoxia
- GNSS positioning and interference
Goddard Space Flight Center
2016-2025
Earth System Science Interdisciplinary Center
2022
University of Maryland, College Park
2022
University of Colorado Boulder
2022
University of Colorado System
2022
National Aeronautics and Space Administration
2019-2020
Naval Research Laboratory Information Technology Division
2019
Victoria University of Wellington
2017
University of Washington
2012-2014
Johns Hopkins University Applied Physics Laboratory
2013-2014
Resting atop a deep marine basin, the West Antarctic Ice Sheet has long been considered prone to instability. Using numerical model, we investigated sensitivity of Thwaites Glacier ocean melt and whether its unstable retreat is already under way. Our model reproduces observed losses when forced with comparable estimates. Simulated are moderate (<0.25 mm per year at sea level) over 21st century but generally increase thereafter. Except possibly for lowest-melt scenario, simulations indicate...
Taking stock of our losses Earth's ice sheets are melting and sea levels rising, so it behooves us to understand better which climate processes responsible for how much the mass loss. Smith et al. estimated grounded floating change Greenland Antarctic from 2003 2019 using satellite laser altimetry data NASA's ICESat ICESat-2 satellites. They show changing flow, melting, precipitation affect different regions estimate that grounded-ice loss averaged close 320 gigatons per year over period...
Abstract. We evaluate modelled Antarctic ice sheet (AIS) near-surface climate, surface mass balance (SMB) and energy (SEB) from the updated polar version of regional atmospheric climate model, RACMO2 (1979–2016). The referred to as RACMO2.3p2, incorporates upper-air relaxation, a revised topography, tuned parameters in cloud scheme generate more precipitation towards AIS interior modified snow properties reducing drifting sublimation increasing snowmelt. Comparisons model output with several...
Abstract This study evaluates the impact of a recent upgrade in physics package regional atmospheric climate model RACMO2 on simulated surface mass balance (SMB) Antarctic ice sheet. The modelled SMB increases, particular over grounded sheet East Antarctica (+44 Gt –1 ), with small change West Antarctica. mainly results from an increase precipitation, which is explained by changes cloud microphysics, including new parameterization for supersaturation, and large-scale circulation patterns,...
Surface mass balance (SMB) provides input to the surface of Antarctic and Greenland Ice Sheets therefore comprises an important control on ice sheet resulting contribution global sea level change. As SMB varies highly across multiple scales space (meters hundreds kilometers) time (hourly decadal), it is notoriously challenging observe represent in models. In addition, consists components, all which depend complex interactions between atmosphere snow/ice surface, large-scale atmospheric...
Abstract. Here we present Antarctic snow accumulation variability at the regional scale over past 1000 years. A total of 79 ice core records were gathered and assigned to seven geographical regions, separating high-accumulation coastal zones below 2000 m elevation from dry central Plateau. The composites annual evaluated against modelled surface mass balance (SMB) RACMO2.3p2 precipitation ERA-Interim reanalysis. With exception Weddell Sea coast, low-elevation capture SMB as defined by...
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...
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...
Abstract The National Aeronautics and Space Administration (NASA)’s Operation IceBridge (OIB) was a 13‐year (2009–2021) airborne mission to survey land sea ice across the Arctic, Antarctic, Alaska. Here, we review OIB’s goals, instruments, campaigns, key scientific results, implications for future investigations of cryosphere. primary goal use laser altimetry bridge gap in fine‐resolution elevation measurements from space between conclusion NASA’s Ice, Cloud, Elevation Satellite (ICESat;...
Abstract Estimating the relative contributions of atmospheric and dynamic components ice‐sheet mass balance is critical for improving projections future sea level rise. Existing estimates changes in Antarctic height, which can be used to infer mass, are only accurate at multiyear time scales. However, NASA's Ice, Cloud, land Elevation Satellite‐2 (ICESat‐2) laser altimetry mission now allows us accurately measure height subannual Here, we use ICESat‐2 data estimate over Antarctica between...
Abstract. Estimates of snow and firn density are required for satellite-altimetry-based retrievals ice sheet mass balance that rely on volume-to-mass conversions. Therefore, biases errors in presently used models confound assessments by extension contribution to sea level rise. Despite this importance, most contemporary densification simplified semi-empirical methods, which partially reflected significant modeled when compared observations. In study, we present a new drifting-snow compaction...
Abstract. Conversion of altimetry-derived ice-sheet volume change to mass requires an understanding the evolution combined ice and air content within firn column. In absence suitable techniques observe changes column across entirety sheet, processes are typically modeled. Here, we present new simulations over Greenland Antarctic sheets (GrIS AIS) using Community Firn Model atmospheric reanalysis variables for more than four decades. A data set 250 measured depth–density profiles from both...
ABSTRACT West Antarctic climate and surface mass balance (SMB) records are sparse. To fill this gap, regional atmospheric modelling is useful, providing that such models employed at sufficiently high horizontal resolution coupled with a snow model. Here we present the results of high-resolution (5.5 km) model (RACMO2) simulation coastal Antarctica for period 1979–2015. We evaluate available in situ weather observations, remote-sensing estimates melt, SMB derived from radar firn cores....
Abstract East Antarctic Ice Sheet (EAIS) mass balance is largely driven by snowfall. Recently, increased snowfall in Queen Maud Land led to years of EAIS gain. It difficult determine whether these enhanced are anomalous or part a longer‐term trend, reducing our ability assess the mitigating impact on sea level rise. We that recent increases western (QML) long‐term trend (+5.2 ± 3.7% decade −1 ) and unprecedented over past two millennia. Warming between 1998 2016 significant rapid (+1.1 0.7°C...
Abstract. Surface-mass-balance (SMB) and firn-densification (FD) models are widely used in altimetry studies as a tool to separate atmospheric-driven from ice-dynamics-driven ice-sheet mass changes partition observed volume into ice-mass firn-air-content changes. Until now, SMB have been principally validated based on comparison with ice core weather station data or separated flight radar-survey lines. Firn-densification primarily their ability match net densification over decades, recorded...
Abstract Our understanding of past sea‐ice variability is limited by the short length satellite and instrumental records. Proxy records can extend these observations but require further development validation. We compare methanesulfonic acid (MSA) chloride (Cl – ) concentrations from a new firn core coastal West Antarctica with satellite‐derived regional concentration (SIC) in Amundsen Sea (AS) to evaluate spatial temporal correlations 2002–2010. The high accumulation rate (~39 g∙cm –2 ∙yr...
Abstract Continent‐wide climate information over the Antarctic Ice Sheet (AIS) is important to obtain accurate of present and reduce uncertainties ice sheet mass balance response resulting global sea level rise future change. In this study, COSMO‐CLM 2 Regional Climate Model applied AIS adapted for specific meteorological climatological conditions region. A 30‐year hindcast was performed evaluated against observational records consisting long‐term ground‐based observations, automatic weather...
Abstract Firn thickness across the NE Greenland Ice Stream is a function of accumulated strain, with thinner firn in high‐strain margins ice stream. We present novel technique for extracting density from previously collected seismic reflection profiles and apply this both shear Stream. up to 30 m vicinity stream margins. Snow accumulation rates were calculated airborne ice‐penetrating radar data, calibrated ground‐based measurements shallow core. find that ~20% higher compared surroundings....
Abstract Although precipitation is a primary control on Antarctic ice sheet (AIS) mass balance, long‐term historical AIS trends and their underlying external climate drivers remain inconclusive. In this study, we use novel pair of model ensembles to identify simulated spatial signature ozone depletion‐forced change. Distinct areas little change or decrease, arising from interaction between atmospheric circulation changes topography, are outweighed by large‐scale increases. This bears notable...
Abstract. Conversion of altimetry-derived ice-sheet volume change to mass requires an understanding the evolution combined ice and air content within firn column. In absence suitable techniques observe changes column across entirety sheet, processes are typically modelled. Here, we present new 40-year simulations over Greenland Antarctic Ice Sheets using Community Firn Model atmospheric reanalysis variables. A dataset more than 250 measured depth-density profiles from both sheets provides...
Microwave radiometry has provided valuable spaceborne observations of Earth's geophysical properties for decades. The recent SMOS, Aquarius, and SMAP satellites have demonstrated the value measurements at 1400 MHz observing surface soil moisture, sea salinity, ice thickness, freeze/thaw state, other variables. However, information obtained is limited by penetration through subsurface a reduced sensitivity to salinity in cold or wind-roughened waters. Recent airborne experiments shown...