Download or read book Assessing the Impact in Using Reanalysis Products to Simulate Surface Mass Balance Over the Greenland Ice Sheet written by Jessica Dawn Kromer and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Greenland ice sheet (GrIS) surface mass balance (SMB), and processes which influence its behavior remain an active area of research, particularly for understanding the current sea-level budget and future projections of ice sheet mass loss. Currently, various methods are employed to model the surface mass balance of the contemporary GrIS, with methodologies ranging from the use of simple positive degree day models (PDD) to computationally intensive energy balance models (EBM's) and regional climate models (RCM's). Many of these methodologies rely on either direct forcing's (EBM's and PDD) or boundary conditions (RCM's) from atmospheric reanalysis products. Over time atmospheric reanalysis products have continued to improve with respect to horizontal resolution, allowing for direct use of fields critical for modeling and understanding the surface mass balance. Here we use a PDD model forced by temperature and precipitation from 3 atmospheric reanalysis products (ERA 5, Arctic System Reanalysis, and MERRA 2) at varying mesh resolution (30 km, 15 km, ~55 km respectively) to simulate the surface mass balance across the GrIS during the period 2000-2016. As higher resolution reanalysis products can help to better understand the contemporary GrIS surface mass balance, we highlight how variables important to the estimation of SMB vary amongst these reanalysis products and how these differences affect the SMB.
Download or read book Effect of Modeled Pre industrial Greenland Ice Sheet Surface Mass Balance Bias on Uncertainty in Sea Level Rise Projections in 2100 written by Gail Ruth Gutowski and published by . This book was released on 2013 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt: Changes to ice sheet surface mass balance (SMB) are going to play a significant role in future sea level rise (SLR), particularly for the Greenland ice sheet. The Coupled Model Intercomparison Project Phase 5 (CMIP5) found that Greenland ice sheet (GIS) response to changes in SMB is expected to contribute 9 ± 4 cm to sea level by 2100 (Fettweis et al 2013), though other estimates suggest the possibility of an even larger response. Modern ice sheet geometry and surface velocities are common metrics for determining a model's predictability of future climate. However, care must be taken to robustly quantify prediction uncertainty because errors in boundary conditions such as SMB can be compensated by (and therefore practically inseparable from) errors in other aspects of the model, complicating calculations of total uncertainty. We find that SMB calculated using the Community Earth System Model (CESM) differs from established standards due to errors in the CESM SMB boundary condition. During the long ice sheet initialization process, small SMB errors such as these have an opportunity to amplify into larger uncertainties in GIS sensitivity to climate change. These uncertainties manifest themselves in ice sheet surface geometry changes, ice mass loss, and subsequent SLR. While any bias in SMB is not desirable, it is not yet clear how sensitive SLR projections are to boundary condition forcing errors. We explore several levels of SMB forcing bias in order to analyze their influence on future SLR. We evaluate ensembles of ice sheets forced by 4 different levels of SMB forcing error, covering a range of errors similar to SMB biases between CESM and RACMO SMB. We find that GIS SMB biases on the order of 1 m/yr result in 7.8 ± 3.4 cm SLR between 1850 and 2100, corresponding to 100% uncertainty at the 2[sigma] level. However, we find unexpected feedbacks between SMB and surface geometry in the northern GIS. We propose that the use of elevation classes may be incorrectly altering the feedback mechanisms in that part of the ice sheet.
Download or read book Improving a Priori Regional Climate Model Estimates of Greenland Ice Sheet Surface Mass Loss Through Assimilation of Measured Ice Surface Temperatures written by Mahdi Navari and published by . This book was released on 2015 with total page 189 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Greenland ice sheet has been the focus of climate studies due to its considerable impact on sea level rise. Accurate estimates of surface mass balance components - including precipitation, runoff, and evaporation - over the Greenland ice sheet would contribute to understanding the cause of the ice sheet's recent changes (i.e., increase in melt amount and duration, thickening of ice sheet interior, thinning at the ice sheet margins) and help to forecast future changes. Deterministic approaches provide a general trend of the surface mass fluxes, but they cannot characterize the uncertainty of estimates. The data assimilation method developed in this dissertation aimed to optimally merge the satellite-derived ice surface temperature into a snow/ice model while taking into account the uncertainty of input variables. Satellite-derived ice surface temperatures were used to improve the estimates of the Greenland ice sheet surface mass fluxes. Three studies were conducted on the Greenland ice sheet. The goal of the first study was to provide a proof of concept of the proposed methodology. A set of observing system simulation experiments was performed to retrieve the true surface mass fluxes of the Greenland ice sheet. The data assimilation framework was able to reduce the RMSE of the prior estimates of runoff, sublimation/evaporation, surface condensation, and surface mass loss fluxes by 61%, 64%, 76%, and 62%, respectively, over the nominal prior estimates from the regional climate model. In the second study, satellite-derived ice surface temperatures were assimilated into a snow/ice model. The results show that the data assimilation framework was capable of retrieving ice surface temperatures with a mean spatial RMSE of 0.3 K which was 69% less than that of the prior estimate without conditioning on satellite-derived ice surface measurements. Evaluation of surface mass fluxes is a critical part of the study; however, it is limited by the spare amount of independent data sets. Several data sets were used to investigate the feasibility of verification of results. It was found that predicted melt duration is in agreement with melt duration from passive microwave measurements; however, more efforts are needed to further verify the results. In the third study, the feasibility of microwave radiance assimilation was investigated by characterizing the error and uncertainty in predicted passive microwave brightness temperature from the radiative transfer model. We found significant uncertainty between the predicted measurement and satellite-derived passive microwave brightness temperature due to error in snow states, coarse resolution of the passive microwave and also an imperfect coupled snow/ice and radiative transfer model. Based on our findings, radiance assimilation requires more accurate snow grain size parameterization to take into account temporal and spatial variability of snow grain size. Furthermore, coarse resolution of both passive microwave brightness temperature and snow/ice model and attribute uncertainties of both predicted and measured brightness temperature make the radiance assimilation unattractive. This research demonstrates that ice surface temperature measurements have valuable information that can be extracted by a data assimilation technique to improve the estimates of the Greenland ice sheet surface mass fluxes.
Download or read book Greenland Ice Sheet Surface Mass balance Modeling in a 131 year Perspective 1950 2080 written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluctuations in the Greenland Ice Sheet (GrIS) surface mass-balance (SMB) and freshwater influx to the surrounding oceans closely follow climate fluctuations and are of considerable importance to the global eustatic sea level rise. SnowModel, a state-of-the-art snow-evolution modeling system, was used to simulate variations in the GrIS melt extent, surface water balance components, changes in SMB, and freshwater influx to the ocean. The simulations are based on the IPCC scenario AlB modeled by the HIRHAM4 RCM (using boundary conditions from ECHAM5 AOGCM) from 1950 through 2080. In-situ meteorological station (GC-Net and WMO DMI) observations from inside and outside the GrIS were used to validate and correct RCM output data before it was used as input for SnowModel. Satellite observations and independent SMB studies were used to validate the SnowModel output and confirm the model's robustness. We simulated a ≈90% increase in end-of-summer surface melt extent (0.483 x 106 km2) from 1950 to 2080, and a melt index (above 2,000-m elevation) increase of 138% (1.96 x 106 km2 x days). The greatest difference in melt extent occured in the southern part of the GrIS, and the greatest changes in the number of melt days was seen in the eastern part of the GrIS (≈50-70%) and was lowest in the west (≈20-30%). The rate of SMB loss, largely tied to changes in ablation processes, lead to an enhanced average loss of 331 km3 from 1950 to 2080, an average 5MB level of -99 km3 for the period 2070-2080. GrIS surface freshwater runoff yielded an eustatic rise in sea level from 0.8 ± 0.1 (1950-1959) to 1.9 ± 0.1 mm (2070-2080) sea level equivalent (SLE) y−1. The accumulated GrIS freshwater runoff contribution from surface melting equaled 160 mm SLE from 1950 through 2080.
Download or read book Oceanobs 19 An Ocean of Opportunity Volume III written by Tong Lee and published by Frontiers Media SA. This book was released on 2020-12-31 with total page 867 pages. Available in PDF, EPUB and Kindle. Book excerpt: This eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contact.
Download or read book Changes in Atmospheric Circulation Over Greenland 19000 32014 written by Joshua Joseph Rosen and published by . This book was released on 2017 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt: The early 21st Century has been characterized by numerous climatic extremes on the Greenland Ice Sheet, with new records set for melt extent and negative surface mass balance. At the same time, the atmospheric circulation over Greenland during the melt season has been characterized by an anomalously high frequency of blocking patterns. Using data from the 20th Century Reanalysis (20CRv2c), and regional climate model Mod©·le Atmosph©♭rique R©♭gional, a summer 500 hPa geopotential height climatology is constructed for the years 19000́32014, using self-organizing maps to examine the linkage between atmospheric circulation and both surface energy and surface mass balance. Results show statistically significant increases in synoptic types that favor meltwater production when comparing the 20th and 21st centuries. The Arctic warm period of the early 20th Century is also examined, with results showing statistically significant increases in synoptic types favoring meltwater production when comparing the 1920s to the 1930s.
Download or read book Assessing Greenland Ice Sheet Albedo and Mass Balance Variability Using in Situ Data Spaceborne Observations and Regional Model Outputs written by Patrick Michael Alexander and published by . This book was released on 2015 with total page 512 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Estimating and Reducing the Uncertainty in the Future Behaviour of the Greenland Ice Sheet written by Peter Fitzgerald and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This study carries out a comprehensive ensemble experiment investigating previously unexplored combinations of model uncertainty in an attempt to quantify and attribute the response uncertainty of future Greenland ice sheet twenty first century simulation. The inclusion of multiple uncertainty sources facilitates the construction of the first ever probability density function (PDF) of Greenland ice sheet surface mass balance (5MB) behaviour over the 21st century. The use of an {insolation temperature' 5MB model permits the inclusion of important ice sheet feedbacks not accounted for in more parameterized models traditionally used in such uncertainty analysis. The lower sensitivity of 'this model (compared to temperature only parameterised models) results in the zi" century 5MB being in the lower end of previously reported ranges. The experiment includes a number of novel methods for downscaling climate data and incorporating new uncertainties such as climate model internal variability. This study also presents a new Bayesian inference method based on summary statistics of present day ice sheet behaviour. The inclusion of internal variability is shown to be crucially important in the Bayesian inference method so that realisations are not highly weighted due to coincidence of random climate fluctuations. Further to this, the long term climate signal is shown to produce too little warming to explain all of the recent runoff trends over the ice sheet, with internal variability accounting for the remainder. Caution must therefore be exercised when extrapolating present ice sheet trends into the future. The application of sensitivity analysis techniques facilitates the identification of important regions that dominate uncertainty, which help to constrain parameter ranges in future sampling within similar models. Climate model uncertainty is shown to dominate zi'' century uncertainty, with the models showing the largest zi" century warming producing the best reconstruction of present day runoff.
Download or read book Surface Mass Balance Model Intercomparison for the Greenland Ice Sheet written by Christopher L. Vernon and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Determining Greenland Ice Sheet Sensitivity to Regional Climate Change written by Nicole-Jeanne Schlegel and published by . This book was released on 2011 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Greenland Ice Sheet, which extends south of the Arctic Circle, is vulnerable to melt in a warming climate. Complete melt of the ice sheet would raise global sea level by about 7 meters. Prediction of how the ice sheet will react to climate change requires inputs with a high degree of spatial resolution and improved simulation of the ice-dynamical responses to evolving surface mass balance. No Greenland Ice Sheet model has yet met these requirements. A three-dimensional thermo-mechanical ice sheet model of Greenland was enhanced to address these challenges. First, it was modified to accept high-resolution surface mass balance forcings. Second, a parameterization for basal drainage (of the sort responsible for sustaining the Northeast Greenland Ice Stream) was incorporated into the model. The enhanced model was used to investigate the century to millennial-scale evolution of the Greenland Ice Sheet in response to persistent climate trends. During initial experiments, the mechanism of flow in the outlet glaciers was assumed to be independent of climate change, and the outlet glaciers' dominant behavior was to counteract changes in surface mass balance. Around much of the ice sheet, warming resulted in calving front retreat and reduction of total ice sheet discharge. Observations show, however, that the character of outlet glacier flow changes with the climate. The ice sheet model was further developed to simulate observed dynamical responses of Greenland's outlet glaciers. A phenomenological description of the relation between outlet glacier discharge and surface mass balance was calibrated against recent observations. This model was used to investigate the ice sheet's response to a hypothesized 21st century warming trend. Enhanced discharge accounted for a 60% increase in Greenland mass loss, resulting in a net sea level increment of 7.3 cm by year 2100. By this time, the average surface mass balance had become negative, and widespread marginal thinning had caused 30% of historically active calving fronts to retreat. Mass losses persisted throughout the century due to flow of dynamically responsive outlets capable of sustaining high calving rates. Thinning in these areas propagated upstream into higher elevation catchments. Large drainage basins with low-lying outlets, especially those along Greenland's west coast and those fed by the Northeast Greenland Ice Stream, were most susceptible to dynamic mass loss in the 21st century.
Download or read book The Impact of 21st Century Arctic Sea Ice Decline on the Climate and Mass Balance of the Greenland Ice Sheet and Svalbard s Glaciers and Ice Caps written by Jonathan Day and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Arctic is a region particularly susceptible to rapid climate change. General circulation models (GCMs) suggest a polar amplification of any global warming signal by a factor of about 1.5 due, in part, to sea ice feed backs. The dramatic recent decline in multi-year sea ice cover lies outside the standard deviation of the CMIP3 ensemble GCM predictions. Sea ice acts as a barrier between cold air and warmer oceans during winter, as well as inhibiting evaporation from the ocean surface water during the summer. An ice free Arctic would likely have an altered hydrological cycle with more evaporation from the ocean surface leading to changes in precipitation distribution and amount. Using the U.K. Met Office Regional Climate Model (RCM), HadRM3, the atmo- spheric effects of the observed and projected reduction in Arctic sea ice are inves- tigated. The RCM is driven by the atmospheric GCM HadAM3. Both models are forced with sea surface temperature and sea ice for the period 2061-2090 from the CMIP3 HadGEM1 experiments. Here we use an RCM at 50km resolution over the Arctic and 25km over Svalbard, which captures well the present-day pattern of pre- cipitation and provides a detailed picture of the projected changes in the behaviour of the oceanic-atmosphere moisture fluxes and how they affect precipitation. These experiments show that the projected 21 stCentury sea ice decline alone causes large impacts to the surface mass balance (SMB) on Svalbard. However Greenland's 5MB is not significantly affected by sea ice decline alone, but responds with a strongly negative shift in 5MB when changes to SST are incorporated into the experiments. This is the first study to characterise the impact of changes in future sea ice to Arctic terrestrial cryosphere mass balance.
Download or read book Mass Balance of Greenland and Antarctica Ice Sheets from Satellite Gravimetry written by Yu Zhang (Ph. D. in geodetic science) and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantitative assessment of the mass balance of polar ice sheets plays an important role in better understanding the response of ice sheets to anthropogenic climate change, the present-day and future global sea level change, and interactions between the ice sheets and the atmosphere, ocean and the solid Earth. In this study, I investigate the mass balance of Greenland and Antarctica ice sheets using Gravity Recovery And Climate Experiment (GRACE) and GRACE Follow-On (GRACE-FO) twin-satellite missions gravity data from April 2002 to August 2020. Auxiliary gravity data from the Swarm mission 3-satellite constellation are also used to support the analysis bridging the GRACE/GRACE-FO data gap (July 2017 to May 2018). Ensemble models are composed combining the official GRACE temporal gravity solutions from CSR, GFZ, JPL and the in-house developed GRACE models using the improved energy balance approach (EBA). The improved atmospheric de-aliasing data produced using the ECMWF (European Centre for Medium-Range Weather Forecasts) Reanalysis 5th Generation (ERA5) data product, and 3-dimensional atmosphere mass computational algorithms are collectively used. The Swarm gravity models are also ensemble of four solutions produced from the kinematic orbit data using four different gravity recovery methods. Post-processing of the gravity models includes replacing low degree spherical harmonic terms (geocenter motions, J2 and J3), destriping filtering, Gaussian smoothing, glacial isostatic adjustment (GIA), forward modeling based signal leakage reduction and ellipsoidal correction. The satellite gravimetric data show that during the period of 2002/04-2020/08, Greenland and Antarctica ice sheets experience rapid mass losses at mean rates of -235.6±3.8 Gt/yr and -122.6±4.6 Gt/yr respectively, equivalent to 0.65 mm/yr and 0.34 mm/yr global sea level changes. In spatial domain, the southern part (including southeast and southwest regions) of Greenland contributes 52.3% of the total Greenland mass loss rate. The West Antarctica (WAIS) losses mass at mean rate of -149.3±3.4 Gt/yr, which accounts for 121.8% of the total Antarctica mass loss rate. The mass gain of +57.2±3.4 Gt/yr in East Antarctica (EAIS) compensates 46.7% of the mass imbalance. Greenland has record-breaking annual mass loss of -461.2±51.8 Gt in 2019. Similarly, Antarctica annual mass loss also sets record at -379.1±90.3 Gt in 2019, mostly due to the abnormal and unprecedented mass loss in EAIS which will be further investigated in the future incorporating independent surface mass balance (SMB) and ice discharge data. The noted abrupt and nonlinear changes in the mass balance of polar ice sheets are presumably due to an increasingly warmer Earth-induced climate episodes with varying time series, from a few years to much longer time periods, along to intraseasonal or shorter changes. It is concluded while the satellite gravimetry climate record is approaching a two decade data span, much longer data are needed to improve our understanding in the complex dynamics of these polar ice sheets responding to climate change.
Download or read book Determining Greenland Ice Sheet Accumulation Rates from Radar Remote Sensing written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-20 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: An important component of NASA's Program for Arctic Regional Climate Assessment (PARCA) is a mass balance investigation of the Greenland Ice Sheet. The mass balance is calculated by taking the difference between the areally Integrated snow accumulation and the net ice discharge of the ice sheet. Uncertainties in this calculation Include the snow accumulation rate, which has traditionally been determined by interpolating data from ice core samples taken from isolated spots across the ice sheet. The sparse data associated with ice cores juxtaposed against the high spatial and temporal resolution provided by remote sensing , has motivated scientists to investigate relationships between accumulation rate and microwave observations as an option for obtaining spatially contiguous estimates. The objective of this PARCA continuation proposal was to complete an estimate of surface accumulation rate on the Greenland Ice Sheet derived from C-band radar backscatter data compiled in the ERS-1 SAR mosaic of data acquired during, September-November, 1992. An empirical equation, based on elevation and latitude, is used to determine the mean annual temperature. We examine the influence of accumulation rate, and mean annual temperature on C-band radar backscatter using a forward model, which incorporates snow metamorphosis and radar backscatter components. Our model is run over a range of accumulation and temperature conditions. Based on the model results, we generate a look-up table, which uniquely maps the measured radar backscatter, and mean annual temperature to accumulation rate. Our results compare favorably with in situ accumulation rate measurements falling within our study area. Jezek, Kenneth C. Goddard Space Flight Center
Download or read book Processes in the Percolation Zone in Southwest Greenland written by Federico Covi and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Increased surface melt in the percolation zone of Greenland causes significant changes in the firn structure, directly affecting the surface mass balance of the ice sheet and the amount and timing of meltwater runoff. Thick impermeable layers, referred to as ice slabs, are preventing melt water percolation and refreezing in the firn favoring lateral movement of water and direct runoff to the oceans. The objective of this dissertation is to enhance the understanding of these processes by modeling the surface energy balance and resulting melt, and investigating the spatial and temporal changes in firn surface properties and associated water movement in the percolation zone in southwest Greenland. Extensive fieldwork was carried out in this region between 2017 and 2019, including a collection of 19 shallow firn cores at several sites and the operation of two weather stations. A surface-energy balance model was forced with automatic weather station data from two sites (2040 and 2360 m a.s.l.). Extensive model validation and sensitivity analysis reveal that the skin layer formulation used to compute the surface temperature by closing the energy balance leads to a consistent overestimation of melt by more than a factor of two or three depending on the site. The results indicate that the energy available for melt is highly sensitive to small changes in surface temperature and suggests caution is needed in modeling Greenland melt from weather data. Furthermore, the spatial and temporal variability in air temperature bias of two regional climate models, MAR and RACMO, is assessed over the entire ice sheet. Model results are compared to 35 automatic weather stations over more than 25 years. Both models perform well in the ablation zone ( 1500 m a.s.l.) where most of the melt happens. However, a warm bias is found in both MAR and RACMO at the higher elevations percolation zone ( 1500 m a.s.l.). The seasonal evolution and interannual variability of near-surface firn characteristics in the percolation zone of southwest Greenland can be tracked with Sentinel-2 optical imagery. Fully saturated seasonal snow (blue slush) and lateral movement of water are strongly correlated with local topography. Furthermore there is evidence of water movement from higher to lower elevations, following surface slope, even after the halting of melt in the second half of August. This suggests that the formation of ice slabs is a self-sustained feedback process increasing the efficiency of the runoff networks in the percolation zone. Ice slabs form and become thicker in areas with smaller surface slope than the surroundings where melt water ponds on top of the impermeable layer, flows, and refreezes during fall, adding to the ice slab. This dissertation provides useful insights on the processes driving ongoing changes in the percolation zone of Greenland due to global warming. However, several questions remain still open. Melt is the main driver of changes. Accurately modeling it, solving the uncertainties in observed and modeled sensible and ground heat flux, is essential. Furthermore, more ground truth and field observations are necessary in the region where blue slush forms on top of ice slabs to quantitatively determine how much water leaves the ice sheet and how much instead refreezes thickening the ice slabs.
Download or read book Ice Sheet Mass Balance Simulations for Greenland and Tibetan Plateau written by Tânia Gil Duarte Casal and published by . This book was released on 2003 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A New Model to Construct Ice Stream Surface Elevation Profiles and Calculate Contributions to Sea Level Rise written by Yosuke Adachi and published by . This book was released on 2012 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sea-level rise is a problem that affects regions worldwide - from the marshlands of the San Francisco Bay Area to the farmlands in coastal Bangladesh. Three-dimensional ice sheet models are the principle tools to evaluate mass loss from ice sheets that contribute to sea-level rise. We recognize that given the current limitations in representing the full extent of dynamical processes that affect ice sheet mass loss in 3-D ice sheet models, we cannot make reliable forecasts of sea-level rise from melting polar land ice. Thus, we take a completely different approach to gaining insight about the potential effects of climate change-induced perturbations on ice sheets. We build a flowline model that resolves the fast-flowing portions of ice sheets (i.e., ice streams). We express the dynamics along the flowline with (a) vertical shear deformation, (b) horizontal shear deformation, and (c) basal slip. Knowledge accumulated from prior force balance analyses performed on some polar ice streams allows us to form relations between (a) and (c), and between (a) and (c) combined and (b). Based on these relationships, we numerically construct surface elevation profiles along flowlines centered on ten select ice streams in Greenland and Antarctica, by prescribing three climate change-induced perturbations: grounding line retreat, ice stream widening, and surface mass balance increase. Comparing these constructed profiles to the current observed ones allows us to quantify the effect of these perturbations on the various characteristics that these ten ice streams possess. Pine Island Glacier, which flows over a long overdeepening, will lose more than half of its stored ice volume that is contributable to sea-level rise before it reaches a possible steady state. Recovery Ice Stream, with its slippery base, long stretch of streaming-flow, and longest flowline among those we examined, loses the most mass (812 km3/km width). Jutulstraumen, which has little room to widen and a short stretch of streaming-flow, experiences more mass gain due to surface mass balance increase than mass loss due to grounding line retreat and widening. The broad range of ice streams and their diverse responses to prescribed perturbations is a convincing message that an accurate assessment of the contribution of ice sheets to future sea-level rise can only be obtained by raising the resolution of models to resolve the fast-flowing features and looking at their mass changes individually over time.
Download or read book Snow and Climate written by Richard L. Armstrong and published by Cambridge University Press. This book was released on 2008-04-24 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the prevailing state of snow-climate science for researchers and advanced students.
