Download or read book Investigation of Mass Balance Parameters on the Greenland Ice Sheet Using Passive Microwave Satellite Data written by Waleed Abdalati and published by . This book was released on 1996 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Analysis of Surface Melting and Snow Accumulation Over the Greenland Ice Sheet from Spaceborne Microwave Sensors written by Indrajit Bhattacharya and published by . This book was released on 2010 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt: Continuous monitoring of changes in the Greenland ice sheet from both space and air borne sensors has been conducted since the early 1970's. Since the mid-1990's dramatic changes occurring on the Greenland ice sheet have been observed both from space borne sensors and field work. These changes, primarily mass loss from the ice sheet, are related to the observed trend of earth's warmer climate in recent decades both in peer reviewed journals and in popular media. This dissertation addresses two parameters that contribute to Greenland ice sheet mass balance estimates. The first factor is characterization of surface melting of the Greenland ice sheet from satellite-based passive and active microwave sensors. We use a wavelet based edge detection technique to delineate surface melt from brightness temperature measured by passive microwave sensors. Along with brightness temperature data, we also use normalized backscatter data from the Quick Scatterometer (QuikSCAT) as an independent sensor for comparison with the radiometer derived results. We use a semi-empirical threshold based method for surface melt detection from QuikSCAT. Our results show a step-like, consistent increase in melt area of the Greenland ice sheet since 1995. This step-like increase is also observed in the mean summer air temperature along portions of the Greenland coast. The 1995 step-like increase of melt area (and melt index, a measure of melt intensity) is correlated with a distinct change of the North Atlantic Oscillation (NAO) index (from positive to negative) after 1995. The second factor is mass accumulation in the upper reaches of the ice-sheet. We use an empirical model that correlates mean annual brightness temperature to annual accumulation rate. We apply a microwave emission model for the dry snow region of Greenland to show that 37 GHz vertically polarized brightness temperature data are better suited to capture the inter-annual variability of snow accumulation. Using our model we estimate a snow accumulation time series from brightness temperature for 150 km x 150 km area around Summit Camp in central Greenland. Using measured surface velocities and ice thickness we calculate the surface mass balance for our study area. We find a positive mass balance of 3.18 ± 6.0 cm/yr. Our mass balance derived elevation change is in agreement with satellite altimeter data and published results of other researchers.
Download or read book Ice and Climate Experiment written by Ice and Climate Experiment. Science and Applications Working Group and published by . This book was released on 1979 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Dissertation Abstracts International written by and published by . This book was released on 1996 with total page 1006 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 2018-06-16 with total page 30 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 snow accumulation and the 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 throughout the ice sheet. The sparse data associated with ice cores, coupled with the high spatial and temporal resolution provided by remote sensing, have motivated scientists to investigate relationships between accumulation rate and microwave observations. Jezek, Kenneth C. Goddard Space Flight Center
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Download or read book Assessment of Climate Variability of the Greenland Ice Sheet Integration of in Situ and Satellite Data written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-10-25 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: The proposed research involves the application of multispectral satellite data in combination with ground truth measurements to monitor surface properties of the Greenland Ice Sheet which are essential for describing the energy and mass of the ice sheet. Several key components of the energy balance are parameterized using satellite data and in situ measurements. The analysis will be done for a ten year time period in order to get statistics on the seasonal and interannual variations of the surface processes and the climatology. Our goal is to investigate to what accuracy and over what geographic areas large scale snow properties and radiative fluxes can be derived based upon a combination of available remote sensing and meteorological data sets. Operational satellite sensors are calibrated based on ground measurements and atmospheric modeling prior to large scale analysis to ensure the quality of the satellite data. Further, several satellite sensors of different spatial and spectral resolution are intercompared to access the parameter accuracy. Proposed parameterization schemes to derive key component of the energy balance from satellite data are validated. For the understanding of the surface processes a field program was designed to collect information on spectral albedo, specular reflectance, soot content, grain size and the physical properties of different snow types. Further, the radiative and turbulent fluxes at the ice/snow surface are monitored for the parameterization and interpretation of the satellite data. The expected results include several baseline data sets of albedo, surface temperature, radiative fluxes, and different snow types of the entire Greenland Ice Sheet. These climatological data sets will be of potential use for climate sensitivity studies in the context of future climate change. Steffen, K. and Abdalati, W. and Stroeve, J. and Key, J. Unspecified Center NAGW-2158
Download or read book Mass Balance of the Cryosphere written by Jonathan L. Bamber and published by Cambridge University Press. This book was released on 2004-02-12 with total page 672 pages. Available in PDF, EPUB and Kindle. Book excerpt: A detailed and comprehensive overview of observational and modelling techniques for all climate change, environmental science and glaciology researchers.
Download or read book Remote Sensing of the Cryosphere written by Marco Tedesco and published by John Wiley & Sons. This book was released on 2015-01-27 with total page 430 pages. Available in PDF, EPUB and Kindle. Book excerpt: The cryosphere, that region of the world where water is temporarily or permanently frozen, plays a crucial role on our planet. Recent developments in remote sensing techniques, and the acquisition of new data sets, have resulted in significant advances in our understanding of all components of the cryosphere and its processes. This book, based on contributions from 40 leading experts, offers a comprehensive and authoritative overview of the methods, techniques and recent advances in applications of remote sensing of the cryosphere. Examples of the topics covered include: • snow extent, depth, grain-size and impurities • surface and subsurface melting • glaciers • accumulation over the Greenland and Antarctica ice sheets • ice thickness and velocities • gravimetric measurements from space • sea, lake and river ice • frozen ground and permafrost • fieldwork activities • recent and future cryosphere-oriented missions and experiments All figures are in color and provide an excellent visual accompaniment to the technical and scientific aspect of the book. Readership: Senior undergraduates, Masters and PhD Students, PostDocs and Researchers in cryosphere science and remote sensing. Remote Sensing of the Cryosphere is the significant first volume in the new Cryosphere Science Series. This new series comprises volumes that are at the cutting edge of new research, or provide focussed interdisciplinary reviews of key aspects of the science.
Download or read book NASA Conference Publication written by and published by . This book was released on 1990 with total page 888 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Earth Observation of Global Change written by Emilio Chuvieco and published by Springer Science & Business Media. This book was released on 2007-11-09 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: Global Change is increasingly considered a critical topic in environmental research. Remote sensing methods provide a useful tool to monitor global variables, since they provide a systematic coverage of the Earth’s surface, at different spatial, spectral and temporal resolutions. This book offers an analysis of the leading missions in global Earth observation, and reviews the main fields in which remote sensing methods are providing vital data for global change studies.
Download or read book Global Land Ice Measurements from Space written by Jeffrey S. Kargel and published by Springer. This book was released on 2014-07-08 with total page 936 pages. Available in PDF, EPUB and Kindle. Book excerpt: An international team of over 150 experts provide up-to-date satellite imaging and quantitative analysis of the state and dynamics of the glaciers around the world, and they provide an in-depth review of analysis methodologies. Includes an e-published supplement. Global Land Ice Measurements from Space - Satellite Multispectral Imaging of Glaciers (GLIMS book for short) is the leading state-of-the-art technical and interpretive presentation of satellite image data and analysis of the changing state of the world's glaciers. The book is the most definitive, comprehensive product of a global glacier remote sensing consortium, Global Land Ice Measurements from Space (GLIMS, http://www.glims.org). With 33 chapters and a companion e-supplement, the world's foremost experts in satellite image analysis of glaciers analyze the current state and recent and possible future changes of glaciers across the globe and interpret these findings for policy planners. Climate change is with us for some time to come, and its impacts are being felt by the world's population. The GLIMS Book, to be released about the same time as the IPCC's 5th Assessment report on global climate warming, buttresses and adds rich details and authority to the global change community's understanding of climate change impacts on the cryosphere. This will be a definitive and technically complete reference for experts and students examining the responses of glaciers to climate change. World experts demonstrate that glaciers are changing in response to the ongoing climatic upheaval in addition to other factors that pertain to the circumstances of individual glaciers. The global mosaic of glacier changes is documented by quantitative analyses and are placed into a perspective of causative factors. Starting with a Foreword, Preface, and Introduction, the GLIMS book gives the rationale for and history of glacier monitoring and satellite data analysis. It includes a comprehensive set of six "how-to" methodology chapters, twenty-five chapters detailing regional glacier state and dynamical changes, and an in-depth summary and interpretation chapter placing the observed glacier changes into a global context of the coupled atmosphere-land-ocean system. An accompanying e-supplement will include oversize imagery and other other highly visual renderings of scientific data.
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 Selected Water Resources Abstracts written by and published by . This book was released on 1990 with total page 1180 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Earth Resources written by and published by . This book was released on 1986 with total page 760 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book SeaRISE written by Robert A. Bindschadler and published by . This book was released on 1990 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of a workshop on the possibility of a rapid rise in sea level following the response of the West Antarctic ice sheet to global warming, and outline of a project to study the phenomenon, called SEARISE : Sea Level Response to Ice Sheet Evolution.
