Ocean tides in GRACE monthly averaged gravity fields

DEFF Research Database (Denmark)

Knudsen, Per

2003-01-01

The GRACE mission will map the Earth's gravity fields and its variations with unprecedented accuracy during its 5-year lifetime. Unless ocean tide signals and their load upon the solid earth are removed from the GRACE data, their long period aliases obscure more subtle climate signals which GRACE...... aims at. In this analysis the results of Knudsen and Andersen (2002) have been verified using actual post-launch orbit parameter of the GRACE mission. The current ocean tide models are not accurate enough to correct GRACE data at harmonic degrees lower than 47. The accumulated tidal errors may affect...... the GRACE data up to harmonic degree 60. A study of the revised alias frequencies confirm that the ocean tide errors will not cancel in the GRACE monthly averaged temporal gravity fields. The S-2 and the K-2 terms have alias frequencies much longer than 30 days, so they remain almost unreduced...

Contributions of GRACE to Climate Monitoring

Science.gov (United States)

Rodell, Matthew; Famiglietti, James; Chambers, Don P.; Wahr, John

2011-01-01

The NASA/German Gravity Recovery and Climate Experiment (GRACE) was launched in March 2002. Rather than looking downward, GRACE continuously monitors the locations of and precise distance between twin satellites which orbit in tandem about 200 km apart. Variations in mass near Earth's surface cause heterogeneities in its gravity field, which in turn affect the orbits of satellites. Thus scientists can use GRACE data to map Earth's gravity field with enough accuracy to discern month to month changes caused by ocean circulation and redistribution of water stored on and in the land. Other gravitational influences, such as atmospheric circulation, post-glacial rebound, and solid earth movements are either independently determined and removed or are negligible on a monthly to sub-decadal timescale. Despite its coarse spatial (>150,000 sq km at mid-latitudes) and temporal (approx monthly) resolutions, GRACE has enabled significant advancements in the oceanic, hydrologic, and cryospheric science, and has great potential for climate monitoring, because it is the only global observing system able to measure ocean bottom pressures, total terrestrial water storage, and ice mass changes. The best known GRACE results are estimates of Greenland and Antarctic ice sheet loss rates. Previously, scientists had estimated ice mass losses using ground and satellite based altimetry and surface mass balance estimates based on snowfall accumulation and glacier discharge. While such measurements are still very useful for their spatial detail, they are imperfectly correlated with large-scale ice mass changes, due to snow and ice compaction and incomplete spatial coverage. GRACE enables scientists to generate monthly time series of Greenland and Antarctic ice mass, which have confirmed the shrinking of the polar ice sheets, one of the most obvious and indisputable manifestations of climate change. Further, GRACE has located and quantified hot spots of ice loss in southeastern Greenland and

Grace and Courtesy: Empowering Children, Liberating Adults

Science.gov (United States)

Sackett, Ginni

2015-01-01

Ginni Sackett delves into the many implications of grace and courtesy, from social relations and the basis of community to respect for the child's personality. Her point of departure is modern social living with grace and dignity. Hers is an exploration over two generations of seeing grace and courtesy as a comprehensive social view that is the…

High-resolution CSR GRACE RL05 mascons

Science.gov (United States)

Save, Himanshu; Bettadpur, Srinivas; Tapley, Byron D.

2016-10-01

The determination of the gravity model for the Gravity Recovery and Climate Experiment (GRACE) is susceptible to modeling errors, measurement noise, and observability issues. The ill-posed GRACE estimation problem causes the unconstrained GRACE RL05 solutions to have north-south stripes. We discuss the development of global equal area mascon solutions to improve the GRACE gravity information for the study of Earth surface processes. These regularized mascon solutions are developed with a 1° resolution using Tikhonov regularization in a geodesic grid domain. These solutions are derived from GRACE information only, and no external model or data is used to inform the constraints. The regularization matrix is time variable and will not bias or attenuate future regional signals to some past statistics from GRACE or other models. The resulting Center for Space Research (CSR) mascon solutions have no stripe errors and capture all the signals observed by GRACE within the measurement noise level. The solutions are not tailored for specific applications and are global in nature. This study discusses the solution approach and compares the resulting solutions with postprocessed results from the RL05 spherical harmonic solutions and other global mascon solutions for studies of Arctic ice sheet processes, ocean bottom pressure variation, and land surface total water storage change. This suite of comparisons leads to the conclusion that the mascon solutions presented here are an enhanced representation of the RL05 GRACE solutions and provide accurate surface-based gridded information that can be used without further processing.

Status of CSR RL06 GRACE reprocessing and preliminary results

Science.gov (United States)

Save, H.

2017-12-01

The GRACE project plans to re-processes the GRACE mission data in order to be consistent with the first gravity products released by the GRACE-FO project. The RL06 reprocessing will harmonize the GRACE time-series with the first release of GRACE-FO. This paper catalogues the changes in the upcoming RL06 release and discusses the quality improvements as compared to the current RL05 release. The processing and parameterization changes as compared to the current release are also discussed. This paper discusses the evolution of the quality of the GRACE solutions and characterize the errors over the past few years. The possible challenges associated with connecting the GRACE time series with that from GRACE-FO are also discussed.

The Light and the Grace: Christian Metaphors

Directory of Open Access Journals (Sweden)

Iacob COMAN

2011-01-01

Full Text Available Our present study continues to provide guidance and meaning for those who are open and have the courage to ask the kind of questions superior to reason. The acceptance of unreasonable realities expresses sometimes the portrait of a non-modern and superstitious man, a portrait dismantled by the contemporary science in order to get the assurance of control over the material and spiritual reality around us. However, the acceptance of unreasonable realities, born by the reason’s questions, expresses in other circumstances the access to super-reason and super-faith. The Light and the Grace from super-existence toward the human nature, and the implications these have, as a divine communication method and metaphors, and as a call to dialogic sharing with the Divine, are the objects of our present study. Super-reason and super-faith can and must characterize also the modern man. The Light and the Grace express both the cause and the means; God who is Light and Grace does communicate Himself in a salvific manner through Light and Grace, and we, as destinations of Light and of Grace can communicate ourselves as Light and Grace to our neighbors.

Earthquake Signal Visible in GRACE Data

Science.gov (United States)

2005-01-01

[figure removed for brevity, see original site] Figure1 This figure shows the effect of the December 2004 great Sumatra earthquake on the Earth's gravity field as observed by GRACE. The signal is expressed in terms of the relative acceleration of the two GRACE satellites, in this case a few nanometers per second squared, or about 1 billionth of the acceleration we experience everyday at the Earth's surface.GRACE observations show comparable signals in the region of the earthquake. Other natural variations are also apparent in the expected places, whereas no other significant change would be expected in the region of the earthquake GRACE, twin satellites launched in March 2002, are making detailed measurements of Earth's gravity field which will lead to discoveries about gravity and Earth's natural systems. These discoveries could have far-reaching benefits to society and the world's population.

Grace and Courtesy across the Planes of Development

Science.gov (United States)

Ludick, Pat

2015-01-01

Pat Ludick's commentary on grace and courtesy is established by a philosophical orientation to development: Grace is oriented to the life of the interior that is consciousness and being, and courtesy moves outward to daily living where civility reflects on success with human interactions. Pat's projected grace and courtesy across the planes is…

Grace buys aquatic quimica to boost water treatment stake

International Nuclear Information System (INIS)

Hunter, D.

1993-01-01

How W.R. Grace (Boca Raton, FL) president and newly appointed CEO J.P. Bolduc plans to expand Grace's core businesses following his drastic portfolio pruning during the past 18 months is a key question for Grace watchers. Grace's acquisition of $70-million/year water treatment firm Aquatec Quimica (Sao Paulo) is one indicator. Grace's $300-million/year Dearborn water treatment business is currently a weak number three [in the world market], and we want to be number one or number two, nothing less, Bolduc insists. The Aquatc buy meets his criterion of a synergistic and strategic acquisition with which he plans to expand the business, backed by more focused R ampersand D. Disposal last month of Homco oil field services operation, for $98.5 million, takes Bolduc toward his $500-million target for the year for asset sales. These totaled $1.1 billion at the end of 1992. The final tally will be more than the $1.5-billion target previously stated, Bolduc says, due to higher realizations on certain sales and additions to the list, including Grace Culinary and Colowyo Coal

Study of Extreme Weather Hazards Using GRACE

Science.gov (United States)

Zhang, Y.; Shum, C. K.; Shang, K.; Guo, J.; Schwartz, F. W.; Akyılmaz, O.; Feng, W.; Forootan, E.; LIU, G.; Zhong, M.

2017-12-01

Extreme weather events significantly affect humans and economics in the region. Synoptic and timely observations of these abrupt meteoro-hydrological hazards would benefit disaster management and improve storm forecasting. Contemporary processing of the Gravity Recovery and Climate Experiment (GRACE) twin-satellite data at monthly sampling would miss or under-sample abrupt events such as large ice storms with durations much shorter than a month. Here, we employ the energy balance approach processing GRACE Level 1 data, which is flexible to allow sub-monthly solutions at daily sampling covering the genesis and evolution of large winter storms. We studied the 2008 Southeast China snow and ice storm, which lasted from mid-January to mid-February, and affected 21 out of China's 34 provinces with heavy snows, ice and freezing rains, caused extensive damage and transportation disruption, displaced nearly 1.7 million people, and claimed 129 lives. We also investigated the devastating North America blizzard which occurred during late January through mid-February 2010. The massive accumulations of snow and ice in both storms slightly changed the gravity field of the Earth, and were sensitive to the GRACE satellite measurements, manifested as transient terrestrial water storage (TWS) change. We compared our solutions with other available high temporal frequency GRACE solutions. The GRACE observed total storage change for both storms are in good agreement with in situ precipitation measurements, and with GRACE observations clearly show the complex genesis, decline, strengthening and melting phases depicting the detailed evolution of these example large snow storms.

Literacy, the American Revolution, and "The Three R's of Our Fight for Freedom": An Interview with Judy McAllister and Erica Lussos.

Science.gov (United States)

Dalton, Bridget, Ed.; Strangman, Nicole, Ed.

2001-01-01

Provides an interview with fourth grade teachers Judy McAllister and Erica Lussos. Discusses the teachers' thoughts on literacy and technology. Explores their ideas on integrating technology in the classroom in innovative ways that motivate and challenge young learners. (PM)

Remote Monitoring of Groundwater Overdraft Using GRACE and InSAR

Science.gov (United States)

Scher, C.; Saah, D.

2017-12-01

Gravity Recovery and Climate Experiment (GRACE) data paired with radar-derived analyses of volumetric changes in aquifer storage capacity present a viable technique for remote monitoring of aquifer depletion. Interferometric Synthetic Aperture Radar (InSAR) analyses of ground level subsidence can account for a significant portion of mass loss observed in GRACE data and provide information on point-sources of overdraft. This study summed one water-year of GRACE monthly mass change grids and delineated regions with negative water storage anomalies for further InSAR analyses. Magnitude of water-storage anomalies observed by GRACE were compared to InSAR-derived minimum volumetric changes in aquifer storage capacity as a result of measurable compaction at the surface. Four major aquifers were selected within regions where GRACE observed a net decrease in water storage (Central Valley, California; Mekong Delta, Vietnam; West Bank, occupied Palestinian Territory; and the Indus Basin, South Asia). Interferogram imagery of the extent and magnitude of subsidence within study regions provided estimates for net minimum volume of groundwater extracted between image acquisitions. These volumetric estimates were compared to GRACE mass change grids to resolve a percent contribution of mass change observed by GRACE likely due to groundwater overdraft. Interferograms revealed characteristic cones of depression within regions of net mass loss observed by GRACE, suggesting point-source locations of groundwater overdraft and demonstrating forensic potential for the use of InSAR and GRACE data in remote monitoring of aquifer depletion. Paired GRACE and InSAR analyses offer a technique to increase the spatial and temporal resolution of remote applications for monitoring groundwater overdraft in addition to providing a novel parameter - measurable vertical deformation at the surface - to global groundwater models.

Teamwork: The methodology for successfully drilling the Judy/Joanne development

International Nuclear Information System (INIS)

Kelly, J.H.

1994-01-01

A non-integrated approach was used to manage development drilling of the Judy/Joanne field. Phillips Petroleum Company United Kingdom Limited (the Operator) elected to retain the role of project and operations coordinator. Others have felt it necessary to integrate the provision of drilling services to achieve operational effectiveness. The Operator approached the management of the operation on a more traditional tack but with the same goal. The management emphasis was on team building and ensuring each party's contribution was optimized. The non-integrated approach to service provision enabled the Operator to maximize the value of in-house experience, to select the preferred suppliers based on safety and operational performance, and to maintain the leading role required of the lease holder. An incentive contract with the drilling contractor rewarded and penalized performance. It provided a win/win arrangement. Contracts with the third party companies were awarded on the basis of best for purpose. The non-integrated approach has proven cost effective and an operational success

[Medicine-syndrome research and analysis of professor Li Dian-gui in treating chronic atrophic gastritis with intestinal metaplasia].

Science.gov (United States)

Liu, Xiao-Fa; Li, Dian-Gui; Liu, Jian-Ping; Du, Yan-Ru; Bai, Hai-Yan

2017-05-01

In this article, medication characteristics of professor Li Dian-gui in treating chronic atrophic gastritis with intestinal metaplasia(CAGIM) were analyzed through traditional Chinese medicine inheritance support system(version 2.5). 276 cases and 625 prescriptions were collected to analyze five types of traditional Chinese medicine(TCM) syndromes and the medicine-syndrome correlation. The results showed that medication characteristics of professor Li Dian-gui in treating CAGIM included drug combination of aromatic medicine bitter-cold herbs, preferring to activating to invigorate the spleen and good at using the qi-regulating drugs. It demonstrated that we can adopt the therapy of Huazhuo Jiedu and Xingpi Xingqi therapies in treating CAGIM in addition to the traditional approach of nourishing Yin and activating blood circulation, opening up a novel approach for TCM in healing the pathema. Copyright© by the Chinese Pharmaceutical Association.

Results from GRACE/SUSY at one-loop

Indian Academy of Sciences (India)

We report the recent development on the SUSY calculations with the help of GRACE system. GRACE/SUSY/1LOOP is the computer code which can generate Feynman diagrams in the MSSM automatically and compute one-loop amplitudes in the numerical way. We present new results of various two-body decay widths ...

Correcting GRACE gravity fields for ocean tide effects

DEFF Research Database (Denmark)

Knudsen, Per; Andersen, Ole Baltazar

2002-01-01

[1] The GRACE mission will be launch in early 2002 and will map the Earth's gravity fields and its variations with unprecedented accuracy during its 5-year lifetime. Unless ocean tide signals and their load upon the solid earth are removed from the GRACE data, their long period aliases obscure more...... tide model if altimetry corrected for inverted barometer effects was used in its derivation. To study the temporal characteristics of the ocean tidal constituents when sampled by GRACE, approximate alias frequencies were derived assuming a sampling of half a sidereal day. Those results show...

Grace and Courtesy in the Elementary Community

Science.gov (United States)

Huneke-Stone, Elise

2015-01-01

Don't be fooled by Elise Huneke-Stone's disarming beginning where she implies that grace and courtesy is not normally associated with the elementary. She goes on to elaborate that grace and courtesy is indeed everywhere: in project-based learning, understanding of moral precepts, social and intellectual independence, in the utilization of empathy,…

Reformation or Revolution? Herman Bavinck and Henri de Lubac on Nature and Grace

Directory of Open Access Journals (Sweden)

Parker Gregory W.

2017-10-01

Full Text Available Henri de Lubac’s treatment of the relationship between nature and grace will be critiqued by Herman Bavinck’s ‘grace restores nature’ theme. In two significant addresses, Bavinck critiqued a Roman Catholic approach to nature and grace. De Lubac’s influence upon Roman Catholic thinking addressing nature and grace occurred post-Bavinck and has altered Catholic thinking on the subject. Neo-Calvinist scholar, Wolter Huttinga admits that Bavinck and de Lubac offer similar critiques of Roman Catholicism (Huttinga 2014. The question remains then, do Bavinck’s critiques still hold? I propose that Bavinck’s account of grace restores nature still makes valid critiques of a post-Vatican II construction of nature and grace. The paper is broken into three sections: (1 an exploration of de Lubac’s nature and grace theme, (2 the framework of Bavinck’s ‘grace restores nature’ theme, and (3 a Bavinckian critique of de Lubac’s nature and grace theme.

GRACE-Assimilated Drought Indicators for the U.S. Drought Monitor

Science.gov (United States)

Rui, Hualan; Vollmer, Bruce; Teng, Bill; Loeser, Carlee; Beaudoing, Hiroko; Rodell, Matt

2018-01-01

The Gravity Recovery and Climate Experiment (GRACE) mission detects changes in Earth's gravity field by precisely monitoring the changes in distance between two satellites orbiting the Earth in tandem. Scientists at NASA's Goddard Space Flight Center generate GRACE-assimilated groundwater and soil moisture drought indicators each week, for drought monitor-related studies and applications. The GRACE-assimilated Drought Indicator Version 2.0 data product (GRACE-DA-DM V2.0) is archived at, and distributed by, the NASA GES DISC (Goddard Earth Sciences Data and Information Services Center). More information about the data and data access is available on the data product landing page at https://disc.gsfc.nasa.gov/datasets /GRACEDADM_CLSM0125US_7D_2.0/summary. The GRACE-DA-DM V2.0 data product contains three drought indicators: Groundwater Percentile, Root Zone Soil Moisture Percentile, and Surface Soil Moisture Percentile. The drought indicators are of wet or dry conditions, expressed as a percentile, indicating the probability of occurrence within the period of record from 1948 to 2012. These GRACE-assimilated drought indicators, with improved spatial and temporal resolutions, should provide a more comprehensive and objective identification of drought conditions. This presentation describes the basic characteristics of the data and data services at NASA GES DISC and collaborative organizations, and uses a few examples to demonstrate the simple ways to explore the GRACE-assimilated drought indicator data.

GRACE star camera noise

Science.gov (United States)

Harvey, Nate

2016-08-01

Extending results from previous work by Bandikova et al. (2012) and Inacio et al. (2015), this paper analyzes Gravity Recovery and Climate Experiment (GRACE) star camera attitude measurement noise by processing inter-camera quaternions from 2003 to 2015. We describe a correction to star camera data, which will eliminate a several-arcsec twice-per-rev error with daily modulation, currently visible in the auto-covariance function of the inter-camera quaternion, from future GRACE Level-1B product releases. We also present evidence supporting the argument that thermal conditions/settings affect long-term inter-camera attitude biases by at least tens-of-arcsecs, and that several-to-tens-of-arcsecs per-rev star camera errors depend largely on field-of-view.

Grace and Courtesy for the Whole School

Science.gov (United States)

Cobb, Mary Lou

2015-01-01

Mary Lou Cobb gives a framework from a very practical point of view, leaning on the aspects of grace and courtesy that are fundamental and arise out of a Montessori administrative point of view. Her examples are pragmatic, such as the grace and courtesy of a greeting, of movement, as a whole-school culture, and the right use of language. She calls…

Living Grace and Courtesy in the Primary

Science.gov (United States)

Soholt, Polli

2015-01-01

Polli Soholt looks at grace and courtesy from the 3-6 classroom perspective with clear theory explanations as they pertain to the larger classroom culture. She discusses the link between older and young children and the presence of the teacher as a model for grace and takes a brief look to neural science for proof of the existence of social…

High-frequency signal and noise estimates of CSR GRACE RL04

Science.gov (United States)

Bonin, Jennifer A.; Bettadpur, Srinivas; Tapley, Byron D.

2012-12-01

A sliding window technique is used to create daily-sampled Gravity Recovery and Climate Experiment (GRACE) solutions with the same background processing as the official CSR RL04 monthly series. By estimating over shorter time spans, more frequent solutions are made using uncorrelated data, allowing for higher frequency resolution in addition to daily sampling. Using these data sets, high-frequency GRACE errors are computed using two different techniques: assuming the GRACE high-frequency signal in a quiet area of the ocean is the true error, and computing the variance of differences between multiple high-frequency GRACE series from different centers. While the signal-to-noise ratios prove to be sufficiently high for confidence at annual and lower frequencies, at frequencies above 3 cycles/year the signal-to-noise ratios in the large hydrological basins looked at here are near 1.0. Comparisons with the GLDAS hydrological model and high frequency GRACE series developed at other centers confirm CSR GRACE RL04's poor ability to accurately and reliably measure hydrological signal above 3-9 cycles/year, due to the low power of the large-scale hydrological signal typical at those frequencies compared to the GRACE errors.

The unrealised ethical potential of the Methodist theology of prevenient grace

Directory of Open Access Journals (Sweden)

David N. Field

2015-10-01

Full Text Available This article examines the unrealised ethical potential of the theology of prevenient grace. It begins with a brief analysis of John Wesley’s rejection of slavery as rooted in his theology of prevenient grace. This is demonstrated in the next section which analyses Wesley’s notion of prevenient grace. This is followed by a constructive proposal for a contemporary theology of prevenient grace and some ethical implications of this theology, for contemporary social and political ethics, are developed.

Estimating continental water storage variations in Central Asia area using GRACE data

International Nuclear Information System (INIS)

Dapeng, Mu; Zhongchang, Sun; Jinyun, Guo

2014-01-01

The goal of GRACE satellite is to determine time-variations of the Earth's gravity, and particularly the effects of fluid mass redistributions at the surface of the Earth. This paper uses GRACE Level-2 RL05 data provided by CSR to estimate water storage variations of four river basins in Asia area for the period from 2003 to 2011. We apply a two-step filtering method to reduce the errors in GRACE data, which combines Gaussian averaging function and empirical de-correlation method. We use GLDAS hydrology to validate the result from GRACE. Special averaging approach is preformed to reduce the errors in GLDAS. The results of former three basins from GRACE are consistent with GLDAS hydrology model. In the Tarim River basin, there is more discrepancy between GRACE and GLDAS. Precipitation data from weather station proves that the results of GRACE are more plausible. We use spectral analysis to obtain the main periods of GRACE and GLDAS time series and then use least squares adjustment to determine the amplitude and phase. The results show that water storage in Central Asia is decreasing

Constraining precipitation amount and distribution over cold regions using GRACE

Science.gov (United States)

Behrangi, A.; Reager, J. T., II; Gardner, A. S.; Fisher, J.

2017-12-01

Current quantitative knowledge on the amount and distribution of precipitation in high-elevation and high latitude regions is limited due to instrumental and retrieval shortcomings. Here we demonstrate how that satellite gravimetry (Gravity Recovery and Climate Experiment, GRACE) can be used to provide an independent estimate of monthly accumulated precipitation using mass balance. Results showed that the GRACE-based precipitation estimate has the highest agreement with most of the commonly used precipitation products in summer, but it deviates from them in cold months, when the other products are expected to have larger error. We also observed that as near surface temperature decreases products tend to underestimate accumulated precipitation retrieved from GRACE. The analysis performed using various products such as GPCP, GPCC, TRMM, and gridded station data over vast regions in high latitudes and two large endorheic basins in High Mountain Asia. Based on the analysis over High Mountain Asia it was found that most of the products capture about or less than 50% of the total precipitation estimated using GRACE in winter. Overall, GPCP showed better agreement with GRACE estimate than other products. Yet on average GRACE showed 30% more annual precipitation than GPCP in the study basin.

Results from GRACE/SUSY at one-loop

International Nuclear Information System (INIS)

Fujimoto, J.; Ishikawa, T.; Kurihara, Y.; Jimbo, M.; Yasui, Y.; Kaneko, T.; Kon, T.; Kuroda, M.; Shimizu, Y.

2007-01-01

We report the recent development on the SUSY calculations with the help of GRACE system. GRACE/SUSY/1LOOP is the computer code which can generate Feynman diagrams in the MSSM automatically and compute one-loop amplitudes in the numerical way. We present new results of various two-body widths and chargino pair production at ILC (international linear collider) at one-loop level. (author)

Judi Dench's age-inappropriateness and the role of M: challenging normative temporality.

Science.gov (United States)

Krainitzki, Eva

2014-04-01

This article approaches Judi Dench's role as M in the long-running James Bond series from a gender and ageing studies' perspective and explores this character's subversion of normative concepts of gender and temporality. Based on the assumption that cultural narratives shape our understanding of ageing, it examines how M disrupts prescribed age- and gender roles, presenting an alternative within films which otherwise perpetuate normative notions of a sexualised, youthful femininity. It focusses on Dench's return as M in Casino Royale (2006), as an instance of anachronism (Russo, 1999), subverting viewers' expectation of linear timelines and examines M's challenge of normative age-appropriateness in Skyfall (2012). Despite M's portrayal as a more vulnerable female character in the latter, this article presents her character as an alternative to traditional portrayals of older women on screen. Copyright © 2014 Elsevier Inc. All rights reserved.

Global inter-annual gravity changes from GRACE: Early results

DEFF Research Database (Denmark)

Andersen, Ole Baltazar; Hinderer, J.

2005-01-01

with an accuracy of 0.4 muGal corresponding to 9 mm water thickness on spatial scales longer than 1300 km. Four of the most widely used global hydrological models have been investigated for their spatial comparison with GRACE observations of inter-annual gravity field variations due to changes in continental water...... storage. The Global Land Data Assimilation System model has a spatial correlation coefficient with GRACE observations of 0.65 over the northern hemisphere. This demonstrates that the observed gravity field changes on these scales are largely related to changes in continental water storage.......Fifteen monthly gravity field solutions from the GRACE twin satellites launched more than two years ago have been studied to estimate gravity field changes between 2002 and 2003. The results demonstrate that GRACE is capable of capturing the changes in ground water on inter-annual scales...

Using GRACE to constrain precipitation amount over cold mountainous basins

Science.gov (United States)

Behrangi, Ali; Gardner, Alex S.; Reager, John T.; Fisher, Joshua B.

2017-01-01

Despite the importance for hydrology and climate-change studies, current quantitative knowledge on the amount and distribution of precipitation in mountainous and high-elevation regions is limited due to instrumental and retrieval shortcomings. Here by focusing on two large endorheic basins in High Mountain Asia, we show that satellite gravimetry (Gravity Recovery and Climate Experiment (GRACE)) can be used to provide an independent estimate of monthly accumulated precipitation using mass balance equation. Results showed that the GRACE-based precipitation estimate has the highest agreement with most of the commonly used precipitation products in summer, but it deviates from them in cold months, when the other products are expected to have larger errors. It was found that most of the products capture about or less than 50% of the total precipitation estimated using GRACE in winter. Overall, Global Precipitation Climatology Project (GPCP) showed better agreement with GRACE estimate than other products. Yet on average GRACE showed 30% more annual precipitation than GPCP in the study basins. In basins of appropriate size with an absence of dense ground measurements, as is a typical case in cold mountainous regions, we find GRACE can be a viable alternative to constrain monthly and seasonal precipitation estimates from other remotely sensed precipitation products that show large bias.

Characteristic mega-basin water storage behavior using GRACE.

Science.gov (United States)

Reager, J T; Famiglietti, James S

2013-06-01

[1] A long-standing challenge for hydrologists has been a lack of observational data on global-scale basin hydrological behavior. With observations from NASA's Gravity Recovery and Climate Experiment (GRACE) mission, hydrologists are now able to study terrestrial water storage for large river basins (>200,000 km 2 ), with monthly time resolution. Here we provide results of a time series model of basin-averaged GRACE terrestrial water storage anomaly and Global Precipitation Climatology Project precipitation for the world's largest basins. We address the short (10 year) length of the GRACE record by adopting a parametric spectral method to calculate frequency-domain transfer functions of storage response to precipitation forcing and then generalize these transfer functions based on large-scale basin characteristics, such as percent forest cover and basin temperature. Among the parameters tested, results show that temperature, soil water-holding capacity, and percent forest cover are important controls on relative storage variability, while basin area and mean terrain slope are less important. The derived empirical relationships were accurate (0.54 ≤  E f  ≤ 0.84) in modeling global-scale water storage anomaly time series for the study basins using only precipitation, average basin temperature, and two land-surface variables, offering the potential for synthesis of basin storage time series beyond the GRACE observational period. Such an approach could be applied toward gap filling between current and future GRACE missions and for predicting basin storage given predictions of future precipitation.

GRACE storage-runoff hystereses reveal the dynamics of ...

Science.gov (United States)

Watersheds function as integrated systems where climate and geology govern the movement of water. In situ instrumentation can provide local-scale insights into the non-linear relationship between streamflow and water stored in a watershed as snow, soil moisture, and groundwater. However, there is a poor understanding of these processes at the regional scale—primarily because of our inability to measure water stores and fluxes in the subsurface. Now NASA’s Gravity Recovery and Climate Experiment (GRACE) satellites quantify changes in the amount of water stored across and through the Earth, providing measurements of regional hydrologic behavior. Here we apply GRACE data to characterize for the first time how regional watersheds function as simple, dynamic systems through a series of hysteresis loops. While the physical processes underlying the loops are inherently complex, the vertical integration of terrestrial water in the GRACE signal provides process-based insights into the dynamic and non-linear function of regional-scale watersheds. We use this process-based understanding with GRACE data to effectively forecast seasonal runoff (mean R2 of 0.91) and monthly runoff (mean R2 of 0.77) in three regional-scale watersheds (>150,000 km2) of the Columbia River Basin, USA. Data from the Gravity Recovery and Climate Experiment (GRACE) satellites provide a novel dataset for understanding changes in the amount of water stored across and through the surface of the Ear

In between St. Augustine and Luther: Grace and justification

Directory of Open Access Journals (Sweden)

Michael M. Ramos

2014-12-01

Full Text Available The view presented in this study emphasized grace as a cause of spiritual strength and justification of man. In understanding the deep meaning and nature of grace, this paper analyzes the formations given on the subject by two great minds, St. Augustine and Martin Luther. Because of the great influence of their work on the theology of grace and justification, this paper attempts to seek whether man’s understanding and belief of prudence would mean nothing at all, that any good that he will perform on his behalf would do nothing for his own justification. Thus it raises the question on the purpose of man’s freedom if his proprium is nothing and that divine prudence is the source of everything good. This led to the idea that grace is the primary energy source of man to make good, not by his own, but by divine prudence to obtain justification. Therefore, in this sense there is nothing good in man.

Saving Grace - A Climate Change Documentary Education Program

Science.gov (United States)

Byrne, J. M.; McDaniel, S.; Graham, J.; Little, L.; Hoggan, J. C.

2012-12-01

Saving Grace conveys climate change knowledge from the best international scientists and social scientists using a series of new media formats. An Education and Communication Plan (ECP) has been developed to disseminate climate change knowledge on impacts, mitigation and adaptation for individuals, and for all sectors of society. The research team is seeking contacts with science and social science colleagues around the world to provide the knowledge base for the ECP. Poverty enslaves…and climate change has, and will, spread and deepen poverty to hundreds of millions of people, primarily in the developing world. And make no mistake; we are enslaving hundreds of millions of people in a depressing and debilitating poverty that in numbers will far surpass the horrors of the slave trade of past centuries. Saving Grace is the story of that poverty - and minimizing that poverty. Saving Grace stars the best of the world's climate researchers. Saving Grace presents the science; who, where and why of greenhouse gases that drive climate change; current and projected impacts of a changing climate around the world; and most important, solutions to the climate change challenges we face.

NASA 3D Models: GRACE

Data.gov (United States)

National Aeronautics and Space Administration — GRACE (Gravity Recovery and Climate Experiment), twin satellites launched in March 2002, are making detailed measurements of Earth's gravity field which will lead to...

NASA 3D Models: Grace

Data.gov (United States)

National Aeronautics and Space Administration — GRACE (Gravity Recovery and Climate Experiment), twin satellites launched in March 2002, are making detailed measurements of Earth's gravity field which will lead to...

GRACE-derived terrestrial water storage depletion associated with the 2003 European heat wave

DEFF Research Database (Denmark)

Andersen, Ole Baltazar; Seneviratne, S.I.; Hinderer, J.

2005-01-01

water storage depletion observed from GRACE can be related to the record-breaking heat wave that occurred in central Europe in 2003. We validate the measurements from GRACE using two independent hydrological estimates and direct gravity observations from superconducting gravimeters in Europe. All...... datasets agree well with the GRACE measurements despite the disparity of the employed information; the difference between datasets tends to be within GRACE margin of error. The April-to-August terrestrial water storage depletion is found to be significantly larger in 2003 than in 2002 from both models......The GRACE twin satellites reveal large inter-annual terrestrial water-storage variations between 2002 and 2003 for central Europe. GRACE observes a negative trend in regional water storage from 2002 to 2003 peaking at -7.8 cm in central Europe with an accuracy of 1 cm. The 2003 excess terrestrial...

Capital Grace of the Word Incarnate According to Saint Thomas Aquinas

Directory of Open Access Journals (Sweden)

Lucia Marie Siemering

2016-06-01

Full Text Available The doctrine of capital grace was developed during the Scholastic period and bears on many areas of theology including ecclesiology, Christology, sacraments, and Trinitarian theology with regard to the missions of the Word and the Holy Spirit. Viewed from a Christological standpoint, capital grace sheds light on how Christ in his human nature can be said to be a source of grace to the members of the Church. Following his contemporaries, the young Thomas Aquinas espoused a view in which Christ is a meritorious, ministerial, and dispositive cause of grace according to his human nature, and an efficient cause according to his divinity. After a deeper reading of John Damascene’s treatment of Christ’s humanity being an instrument of his divinity, Thomas was able to articulate a view in which Christ’s human nature is an instrumental efficient cause of grace. This view undergirds Aquinas’s strong conception of Christ as one acting person in two natures.

Global Assessment of New GRACE Mascons Solutions for Hydrologic Applications

Science.gov (United States)

Save, H.; Zhang, Z.; Scanlon, B. R.; Wiese, D. N.; Landerer, F. W.; Long, D.; Longuevergne, L.; Chen, J.

2016-12-01

Advances in GRACE (Gravity Recovery and Climate Experiment) satellite data processing using new mass concentration (mascon) solutions have greatly increased the spatial localization and amplitude of recovered total Terrestrial Water Storage (TWS) signals; however, limited testing has been conduct on land hydrologic applications. In this study we compared TWS anomalies from (1) Center for Space Research mascons (CSR-M) solution with (2) NASA JPL mascon (JPL-M) solution, and with (3) a CSR gridded spherical harmonic rescaled (sf) solution from Tellus (CSRT-GSH.sf) in 176 river basins covering 80% of the global land area. There is good correspondence in TWS anomalies from mascons (CSR-M and JPL-M) and SH solutions based on high correlations between time series (rank correlation coefficients mostly >0.9). The long-term trends in basin TWS anomalies represent a relatively small signal (up to ±20 mm/yr) with differences among GRACE solutions and inter-basin variability increasing with decreasing basin size. Long-term TWS declines are greatest in (semi)arid and irrigated basins. Annual and semiannual signals have much larger amplitudes (up to ±250 mm). There is generally good agreement among GRACE solutions, increasing confidence in seasonal fluctuations from GRACE data. Rescaling spherical harmonics to restore lost signal increases agreement with mascons solutions for long-term trends and seasonal fluctuations. There are many advantages to using GRACE mascons solutions relative to SH solutions, such as reduced leakage from land to ocean increasing signal amplitude, and constraining results by applying geophysical data during processing with little or no post-processing requirements, making mascons more user friendly for non-geodetic users. This inter-comparison of various GRACE solutions should allow hydrologists to better select suitable GRACE products for hydrologic applications.

Predictive power of the grace score in population with diabetes.

Science.gov (United States)

Baeza-Román, Anna; de Miguel-Balsa, Eva; Latour-Pérez, Jaime; Carrillo-López, Andrés

2017-12-01

Current clinical practice guidelines recommend risk stratification in patients with acute coronary syndrome (ACS) upon admission to hospital. Diabetes mellitus (DM) is widely recognized as an independent predictor of mortality in these patients, although it is not included in the GRACE risk score. The objective of this study is to validate the GRACE risk score in a contemporary population and particularly in the subgroup of patients with diabetes, and to test the effects of including the DM variable in the model. Retrospective cohort study in patients included in the ARIAM-SEMICYUC registry, with a diagnosis of ACS and with available in-hospital mortality data. We tested the predictive power of the GRACE score, calculating the area under the ROC curve. We assessed the calibration of the score and the predictive ability based on type of ACS and the presence of DM. Finally, we evaluated the effect of including the DM variable in the model by calculating the net reclassification improvement. The GRACE score shows good predictive power for hospital mortality in the study population, with a moderate degree of calibration and no significant differences based on ACS type or the presence of DM. Including DM as a variable did not add any predictive value to the GRACE model. The GRACE score has an appropriate predictive power, with good calibration and clinical applicability in the subgroup of diabetic patients. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.

Can GRACE detect winter snows in Japan?

Science.gov (United States)

Heki, Kosuke

2010-05-01

Current spatial resolution of the GRACE (Gravity Recovery and Climate Experiment) satellites is 300-400 km, and so its hydrological applications have been limited to continents and large islands. The Japanese Islands have width slightly smaller than this spatial resolution, but are known to show large amplitude seasonal changes in surface masses due mainly to winter snow. Such loads are responsible for seasonal crustal deformation observed with GEONET, a dense array of GPS (Global Positioning System) receivers in Japan (Heki, 2001). There is also a dense network of surface meteorological sensors for, e.g. snow depths, atmospheric pressures, etc. Heki (2004) showed that combined effects of surface loads, i.e. snow (predominant), atmosphere, soil moisture, dam impoundment, can explain seasonal crustal deformation observed by GPS to a large extent. The total weight of the winter snow in the Japanese Islands in its peak season may reach ~50 Gt. This is comparable to the annual loss of mountain glaciers in the Asian high mountains (Matsuo & Heki, 2010), and is above the detection level of GRACE. In this study, I use GRACE Level-2 Release-4 data from CSR, Univ. Texas, up to 2009 November, and evaluated seasonal changes in surface loads in and around the Japanese Islands. After applying a 350 km Gaussian filter and a de-striping filter, the peak-to-peak change of the water depth becomes ~4 cm in northern Japan. The maximum value is achieved in February-March. The region of large winter load spans from Hokkaido, Japan, to northeastern Honshu, which roughly coincides with the region of deep snow in Japan. Next I compiled snow depth data from surface meteorological observations, and converted them to loads using time-dependent snow density due to compaction. By applying the same spatial filter as the GRACE data, its spatial pattern becomes similar to the GRACE results. The present study suggests that GRACE is capable of detecting seasonal mass changes in an island arc not

Benefits and Pitfalls of GRACE Terrestrial Water Storage Data Assimilation

Science.gov (United States)

Girotto, Manuela

2018-01-01

Satellite observations of terrestrial water storage (TWS) from the Gravity Recovery and Climate Experiment (GRACE) mission have a coarse resolution in time (monthly) and space (roughly 150,000 sq km at midlatitudes) and vertically integrate all water storage components over land, including soil moisture and groundwater. Nonetheless, data assimilation can be used to horizontally downscale and vertically partition GRACE-TWS observations. This presentation illustrates some of the benefits and drawbacks of assimilating TWS observations from GRACE into a land surface model over the continental United States and India. The assimilation scheme yields improved skill metrics for groundwater compared to the no-assimilation simulations. A smaller impact is seen for surface and root-zone soil moisture. Further, GRACE observes TWS depletion associated with anthropogenic groundwater extraction. Results from the assimilation emphasize the importance of representing anthropogenic processes in land surface modeling and data assimilation systems.

Reducing errors in the GRACE gravity solutions using regularization

Science.gov (United States)

Save, Himanshu; Bettadpur, Srinivas; Tapley, Byron D.

2012-09-01

The nature of the gravity field inverse problem amplifies the noise in the GRACE data, which creeps into the mid and high degree and order harmonic coefficients of the Earth's monthly gravity fields provided by GRACE. Due to the use of imperfect background models and data noise, these errors are manifested as north-south striping in the monthly global maps of equivalent water heights. In order to reduce these errors, this study investigates the use of the L-curve method with Tikhonov regularization. L-curve is a popular aid for determining a suitable value of the regularization parameter when solving linear discrete ill-posed problems using Tikhonov regularization. However, the computational effort required to determine the L-curve is prohibitively high for a large-scale problem like GRACE. This study implements a parameter-choice method, using Lanczos bidiagonalization which is a computationally inexpensive approximation to L-curve. Lanczos bidiagonalization is implemented with orthogonal transformation in a parallel computing environment and projects a large estimation problem on a problem of the size of about 2 orders of magnitude smaller for computing the regularization parameter. Errors in the GRACE solution time series have certain characteristics that vary depending on the ground track coverage of the solutions. These errors increase with increasing degree and order. In addition, certain resonant and near-resonant harmonic coefficients have higher errors as compared with the other coefficients. Using the knowledge of these characteristics, this study designs a regularization matrix that provides a constraint on the geopotential coefficients as a function of its degree and order. This regularization matrix is then used to compute the appropriate regularization parameter for each monthly solution. A 7-year time-series of the candidate regularized solutions (Mar 2003-Feb 2010) show markedly reduced error stripes compared with the unconstrained GRACE release 4

Synergies Between Grace and Regional Atmospheric Modeling Efforts

Science.gov (United States)

Kusche, J.; Springer, A.; Ohlwein, C.; Hartung, K.; Longuevergne, L.; Kollet, S. J.; Keune, J.; Dobslaw, H.; Forootan, E.; Eicker, A.

2014-12-01

In the meteorological community, efforts converge towards implementation of high-resolution (precipitation, evapotranspiration and runoff data; confirming that the model does favorably at representing observations. We show that after GRACE-derived bias correction, basin-average hydrological conditions prior to 2002 can be reconstructed better than before. Next, comparing GRACE with CLM forced by EURO-CORDEX simulations allows identifying processes needing improvement in the model. Finally, we compare COSMO-EU atmospheric pressure, a proxy for mass corrections in satellite gravimetry, with ERA-Interim over Europe at timescales shorter/longer than 1 month, and spatial scales below/above ERA resolution. We find differences between regional and global model more pronounced at high frequencies, with magnitude at sub-grid scale and larger scale corresponding to 1-3 hPa (1-3 cm EWH); relevant for the assessment of post-GRACE concepts.

Marriage and Sexuality in Pearl Abraham’s The Romance Reader and Hush by Judy Brown

Directory of Open Access Journals (Sweden)

Eva van Loenen

2018-01-01

Full Text Available This article examines two authors’ perspectives on marriage and sexuality in Hasidic Judaism through the leading female characters in their semi-autobiographical novels: 'The Romance Reader' by Pearl Abraham and 'Hush' by Judy Brown. Each novel features an adolescent woman on her path to marriage and their experience of matrimony and sexuality within their respective Hasidic communities. The aim of the article is to analyse and compare their views in order to gain a better understanding of the female experience of sexuality and marriage within contemporary Hasidic Judaism. Furthermore, this article discusses the treatment of sexual abuse within a particular Hasidic group. It employs a methodology of close reading combined with a discussion of Talmudic, theological, sociological and ethnographic commentaries on the subject.

Sensitivity of GRACE-derived estimates of groundwater-level changes in southern Ontario, Canada

Science.gov (United States)

Hachborn, Ellen; Berg, Aaron; Levison, Jana; Ambadan, Jaison Thomas

2017-12-01

Amidst changing climates, understanding the world's water resources is of increasing importance. In Ontario, Canada, low water conditions are currently assessed using only precipitation and watershed-based stream gauges by the Conservation Authorities in Ontario and the Ministry of Natural Resources and Forestry. Regional groundwater-storage changes in Ontario are not currently measured using satellite data by research institutes. In this study, contributions from the Gravity Recovery and Climate Experiment (GRACE) data are compared to a hydrogeological database covering southern Ontario from 2003 to 2013, to determine the suitability of GRACE total water storage estimates for monitoring groundwater storage in this location. Terrestrial water storage data from GRACE were used to determine monthly groundwater storage (GWS) anomaly values. GWS values were also determined by multiplying groundwater-level elevations (from the Provincial Groundwater Monitoring Network wells) by specific yield. Comparisons of GRACE-derived GWS to well-based GWS data determined that GRACE is sufficiently sensitive to obtain a meaningful signal in southern Ontario. Results show that GWS values produced by GRACE are useful for identifying regional changes in groundwater storage in areas with limited available hydrogeological characterization data. Results also indicate that GRACE may have an ability to forecast changes in groundwater storage, which will become useful when monitoring climate shifts in the near future.

GRACE manual

International Nuclear Information System (INIS)

Ishikawa, T.; Kawabata, S.; Shimizu, Y.; Kaneko, T.; Kato, K.; Tanaka, H.

1993-02-01

This manual is composed of three kinds of objects, theoretical background for calculating the cross section of elementary process, usage and technical details of the GRACE system. Throughout this manual we take the tree level process e + e - → W + W - γ as an example, including the e ± -scalar boson interactions. The real FORTRAN source code for this process is attached in the relevant sections as well as the results of calculation, which might be a great help for understanding the practical use of the system. (J.P.N.)

Automatic computation of cross sections in HEP. Status of GRACE system

International Nuclear Information System (INIS)

Yuasa, F.; Fujimoto, J.; Ishikawa, T.

2000-01-01

For the study of reactions in High Energy Physics (HEP) automatic computation systems have been developed are widely used nowadays. GRACE is one of such systems and it has achieved much success in analyzing experimental data. Since we deal with the cross section whose value can be given by calculating hundreds of Feynman diagrams, we manage the large scale calculation, so that effective symbolic manipulation, the treat of singularity in the numerical integration are required. The talk will describe the software design of GRACE system and computational techniques in the GRACE. (author)

Assimilation of Gridded GRACE Terrestrial Water Storage Estimates in the North American Land Data Assimilation System

Science.gov (United States)

Kumar, Sujay V.; Zaitchik, Benjamin F.; Peters-Lidard, Christa D.; Rodell, Matthew; Reichle, Rolf; Li, Bailing; Jasinski, Michael; Mocko, David; Getirana, Augusto; De Lannoy, Gabrielle;

Percepción de servicios para la Dirección de Impuestos y Aduanas Nacionales DIAN

OpenAIRE

Casallas Ariza, Ricardo Andres; Castellote Lozano, Alejandra; Garavito Lopez, Julio Humberto

2013-01-01

Los servicios prestados por parte de una entidad como lo es la DIAN, que tiene como función garantizar el cumplimiento de las obligaciones tributarias aduaneras y cambiarias y facilitar las operaciones de comercio internacional es fundamental en el país, ya que ayudan al desarrollo competitivo del mismo. Entendiendo la importancia que tiene la satisfacción del cliente, este trabajo, que tiene carácter investigativo y descriptivo, identificó las percepciones que tienen los usuarios de la ...

GRACE score predicts heart failure admission following acute coronary syndrome.

Science.gov (United States)

McAllister, David A; Halbesma, Nynke; Carruthers, Kathryn; Denvir, Martin; Fox, Keith A

2015-04-01

Congestive heart failure (CHF) is a common and preventable complication of acute coronary syndrome (ACS). Nevertheless, ACS risk scores have not been shown to predict CHF risk. We investigated whether the at-discharge Global Registry of Acute Coronary Events (GRACE) score predicts heart failure admission following ACS. Five-year mortality and hospitalization data were obtained for patients admitted with ACS from June 1999 to September 2009 to a single centre of the GRACE registry. CHF was defined as any admission assigned WHO International Classification of Diseases 10 diagnostic code I50. The hazard ratio (HR) for CHF according to GRACE score was estimated in Cox models adjusting for age, gender and the presence of CHF on index admission. Among 1,956 patients, CHF was recorded on index admission in 141 patients (7%), and 243 (12%) were admitted with CHF over 3.8 median years of follow-up. Compared to the lowest quintile, patients in the highest GRACE score quintile had more CHF admissions (116 vs 17) and a shorter time to first admission (1.2 vs 2.0 years, HR 9.87, 95% CI 5.93-16.43). Per standard deviation increment in GRACE score, the instantaneous risk was more than two-fold higher (HR 2.28; 95% CI 2.02-2.57), including after adjustment for CHF on index admission, age and gender (HR 2.49; 95% CI 2.06-3.02). The C-statistic for CHF admission at 1-year was 0.74 (95% CI 0.70-0.79). The GRACE score predicts CHF admission, and may therefore be used to target ACS patients at high risk of CHF with clinical monitoring and therapies. © The European Society of Cardiology 2014.

Towards Designing Graceful Degradation into Trajectory Based Operations: A Human-systems Integration Approach

Science.gov (United States)

Edwards, Tamsyn; Lee, Paul

2017-01-01

One of the most fundamental changes to the air traffic management system in NextGen is the concept of trajectory based operations (TBO). With the introduction of such change, system safety and resilience is a critical concern, in particular, the ability of systems to gracefully degrade. In order to design graceful degradation into a TBO envrionment, knowledge of the potential causes of degradation, and appropriate solutions, is required. In addition, previous research has predominantly explored the technological contribution to graceful degradation, frequently neglecting to consider the role of the human operator, specifically, air traffic controllers (ATCOs). This is out of step with real-world operations, and potentially limits an ecologically valid understanding of achieving graceful degradation in an air traffic control (ATC) environment. The following literature review aims to identify and summarize the literature to date on the potential causes of degradation in ATC and the solutions that may be applied within a TBO context, with a specific focus on the contribution of the air traffic controller. A framework of graceful degradation, developed from the literature, is presented. It is argued that in order to achieve graceful degradation within TBO, a human-system integration approach must be applied.

The Value of Information from a GRACE-Enhanced Drought Severity Index

Science.gov (United States)

Kuwayama, Y.; Bernknopf, R.; Macauley, M.; Brookshire, D.; Zaitchik, B. F.; Rodell, M.

2013-12-01

Water storage anomalies derived from the Gravity Recovery and Climate Experiment Data Assimilation System (GRACE-DAS) have been used to enhance the information contained in drought indicators. The potential value of this information is to inform local and regional decisions to improve economic welfare in the face of drought. Based on a characterization of current drought evaluations, a modeling framework has been structured to analyze the contributed value of the Earth observations in the assessment of the onset and duration of droughts and their regional impacts. The analysis focuses on (1) characterizing how GRACE-DAS provides Earth observation information for a drought warning, (2) assessing how a GRACE-DAS-enhanced U.S. Drought Monitor would improve economic outcomes in a region, and (3) applying this enhancement process in a decision framework to illustrate the potential role of GRACE data products in a recent drought and response scenario for a value-of-information (VOI) analysis. The VOI analysis quantifies the relative contribution of enhanced understanding and communication of the societal benefits associated with GRACE Earth observation science. Our emphasis is to illustrate the role of an enhanced National Integrated Drought Information System outlook on three key societal outcomes: effects on particular economic sectors, changes in land management decisions, and reductions in damages to ecosystem services.

New GRACE-Derived Storage Change Estimates Using Empirical Mode Extraction

Science.gov (United States)

Aierken, A.; Lee, H.; Yu, H.; Ate, P.; Hossain, F.; Basnayake, S. B.; Jayasinghe, S.; Saah, D. S.; Shum, C. K.

2017-12-01

Estimated mass change from GRACE spherical harmonic solutions have north/south stripes and east/west banded errors due to random noise and modeling errors. Low pass filters like decorrelation and Gaussian smoothing are typically applied to reduce noise and errors. However, these filters introduce leakage errors that need to be addressed. GRACE mascon estimates (JPL and CSR mascon solutions) do not need decorrelation or Gaussian smoothing and offer larger signal magnitudes compared to the GRACE spherical harmonics (SH) filtered results. However, a recent study [Chen et al., JGR, 2017] demonstrated that both JPL and CSR mascon solutions also have leakage errors. We developed a new postprocessing method based on empirical mode decomposition to estimate mass change from GRACE SH solutions without decorrelation and Gaussian smoothing, the two main sources of leakage errors. We found that, without any post processing, the noise and errors in spherical harmonic solutions introduced very clear high frequency components in the spatial domain. By removing these high frequency components and reserve the overall pattern of the signal, we obtained better mass estimates with minimum leakage errors. The new global mass change estimates captured all the signals observed by GRACE without the stripe errors. Results were compared with traditional methods over the Tonle Sap Basin in Cambodia, Northwestern India, Central Valley in California, and the Caspian Sea. Our results provide larger signal magnitudes which are in good agreement with the leakage corrected (forward modeled) SH results.

Quantitative Amyloid Imaging in Autosomal Dominant Alzheimer's Disease: Results from the DIAN Study Group.

Directory of Open Access Journals (Sweden)

Yi Su

Full Text Available Amyloid imaging plays an important role in the research and diagnosis of dementing disorders. Substantial variation in quantitative methods to measure brain amyloid burden exists in the field. The aim of this work is to investigate the impact of methodological variations to the quantification of amyloid burden using data from the Dominantly Inherited Alzheimer's Network (DIAN, an autosomal dominant Alzheimer's disease population. Cross-sectional and longitudinal [11C]-Pittsburgh Compound B (PiB PET imaging data from the DIAN study were analyzed. Four candidate reference regions were investigated for estimation of brain amyloid burden. A regional spread function based technique was also investigated for the correction of partial volume effects. Cerebellar cortex, brain-stem, and white matter regions all had stable tracer retention during the course of disease. Partial volume correction consistently improves sensitivity to group differences and longitudinal changes over time. White matter referencing improved statistical power in the detecting longitudinal changes in relative tracer retention; however, the reason for this improvement is unclear and requires further investigation. Full dynamic acquisition and kinetic modeling improved statistical power although it may add cost and time. Several technical variations to amyloid burden quantification were examined in this study. Partial volume correction emerged as the strategy that most consistently improved statistical power for the detection of both longitudinal changes and across-group differences. For the autosomal dominant Alzheimer's disease population with PiB imaging, utilizing brainstem as a reference region with partial volume correction may be optimal for current interventional trials. Further investigation of technical issues in quantitative amyloid imaging in different study populations using different amyloid imaging tracers is warranted.

77 FR 73452 - Grace Period Study

Science.gov (United States)

2012-12-10

... survey may be distributed in waves for convenience. The Grace Period Study survey will be an electronic... information that is used for sampling purposes will be maintained in a separate file from the quantitative...

Kantian Grace as Ethical Gymnastics

NARCIS (Netherlands)

Vanden Auweele, Dennis

2017-01-01

Kant’s concept of grace in Religion within the Bounds of Mere Reason is a difficult topic, exegetically speaking. Obviously enough, Kant subscribes positively to a notion of divine assistance. This appears awkward given his rationalist ethics rooted in personal autonomy. This has given cause to

Picking winners. Interview by Diane Coutu.

Science.gov (United States)

Socolow, Daniel J

2007-05-01

In the business world, "creativity" has become the latest buzzword. How to attract, nurture, and direct the extraordinarily talented people who will come up with the next Lipitor, SonyWalkman, or iPod is an enduring topic among business-people. As the director of the MacArthur Fellows Program, Daniel J. Socolow has considerable experience with the process of rooting out creativity. In this conversation with HBR senior editor Diane Coutu, he describes how recipients of the "genius grant"--half a million dollars with no strings attached--are chosen. As significant as the money is, the recognition that comes with a fellowship may be more so. MacArthur grants provide powerful validation of the fellows' work, Socolow says, and that validation opens doors for people, whatever the field. Although the program keeps a lookout for entrepreneurs who are on the brink of major new advances, he believes that the market does a good job of rewarding the best ideas in business. Replicating the MacArthur model in a company would entail giving some employees unlimited time and lots of money to follow their own inclinations--not very feasible in most contexts. Nevertheless, the program has learned a lesson that may be valuable for business: The kind of creativity that leads to important breakthroughs is extremely hard to find. And, says Socolow, exceptionally creative people aren't always the obvious suspects, who may simply be good at promoting themselves: "Listen to others and look in the least likely places ... Extend your networks and try to get information from as many people as possible, just as we do".

How Do We Defend Democratic Education? Lois Weiner and Andy Kaplan Respond to Diane Ravitch's "The Reign of Error"

Science.gov (United States)

Weiner, Lois; Kaplan, Andy

2014-01-01

In this commentary, Andy Kaplan discusses with Lois Weiner, Diane Ravitch's latest book "The Reign of Error," which combines scholarly argument and scrupulous research in defense of democratic education. Weiner notes, the book will prove an important resource in the ongoing struggle for the survival of public schooling. Weiner adds,…

Greenland ice mass balance from GPS, GRACE and ICESat

DEFF Research Database (Denmark)

Khan, Shfaqat Abbas; Kjær, Kurt H.; Korsgaard, Niels Jákup

Greenland, using stereoscopic coverage by aerial photographs recorded in 1985, and subsequent comparative surface elevation data from ICESat (Ice, Cloud and land Elevation Satellite) and ATM (Airborne Topographic Mapper) supplemented with measurements from GPS and the Gravity Recovery and Climate Experiment...... (GRACE) satellite gravity mission, launched in March, 2002. The GRACE results provide a direct measure of mass loss, while the GPS data are used to monitor crustal uplift caused by ice mass loss close to the GPS sites....

Dian Sastrowardjojo Sebagai Citra Produk Untuk Iklan Kartu Perdana Mentari Free Talk di Surat Kabar

Directory of Open Access Journals (Sweden)

Hendro Aryanto

2010-01-01

Full Text Available Advertisements do not just sell goods or services, but also reflect certain cultural aspects to their viewers because they attempt to change people’s lifestyles. Ads simplify lives, therefore do not see other factors that can contribute to happiness in life. The visualization for Mentari Free Talk SIM card advertisement shows the presence of social codes phenomenon that take on the gender perspective through the figure Dian Sastro, which are beauty, intelligence, and an artist who’s gaining popularity. Woman in this case becomes a means to identify a product in its ability in creating visibility or product image.

Towards Designing Graceful Degradation into Trajectory Based Operations: A Human-Machine System Integration Approach

Science.gov (United States)

Edwards, Tamsyn; Lee, Paul

2017-01-01

One of the most fundamental changes to the air traffic management system in NextGen is the concept of trajectory based operations (TBO). With the introduction of such change, system safety and resilience is a critical concern, in particular, the ability of systems to gracefully degrade. In order to design graceful degradation into a TBO envrionment, knowledge of the potential causes of degradation, and appropriate solutions, is required. In addition, previous research has predominantly explored the technological contribution to graceful degradation, frequently neglecting to consider the role of the human operator, specifically, air traffic controllers (ATCOs). This is out of step with real-world operations, and potentially limits an ecologically valid understanding of achieving graceful degradation in an air traffic control (ATC) environment. The following literature review aims to identify and summarize the literature to date on the potential causes of degradation in ATC and the solutions that may be applied within a TBO context, with a specific focus on the contribution of the air traffic controller. A framework of graceful degradation, developed from the literature, is presented. It is argued that in order to achieve graceful degradation within TBO, a human-system integration approach must be applied.

Using GPS and GRACE data to assess Solid Earth elastic parameters at regional scale

DEFF Research Database (Denmark)

Barletta, Valentina Roberta; Borghi, A.; Aoudia, A.

2012-01-01

We propose a way to combine GPS and GRACE data for regional scale cross check and validation especially of the most commonly used PREM (Preliminary Earth Reference Model). In form of h and k Love numbers, global PREM is very often used to simulate elastic rebound due to present-day ice mass loss......, to derive the mass distribution produced by the observed GRACE time series, and it is also used for atmospheric loading correction both in GPS and in GRACE dealiasing products. GRACE data provide load estimates, usually given as water equivalent mass distribution, from which one derives the Earth elastic...... response, by convolution with suitable elastic green functions, relying on selected Earth model and related layering and elastic parameters. We calculate at regional scale the time series of monthly uplift associated with the mass redistribution observed by GRACE implementing the high resolution technique...

Low-degree gravity change from GPS data of COSMIC and GRACE satellite missions

Science.gov (United States)

Lin, Tingjung; Hwang, Cheinway; Tseng, Tzu-Pang; Chao, B. F.

2012-01-01

This paper demonstrates estimation of time-varying gravity harmonic coefficients from GPS data of COSMIC and GRACE satellite missions. The kinematic orbits of COSMIC and GRACE are determined to the cm-level accuracy. The NASA Goddard's GEODYN II software is used to model the orbit dynamics of COSMIC and GRACE, including the effect of a static gravity field. The surface forces are estimated per one orbital period. Residual orbits generated from kinematic and reference orbits serve as observables to determine the harmonic coefficients in the weighted-constraint least-squares. The monthly COSMIC and GRACE GPS data from September 2006 to December 2007 (16 months) are processed to estimate harmonic coefficients to degree 5. The geoid variations from the GPS and CSR RL04 (GRACE) solutions show consistent patterns over space and time, especially in regions of active hydrological changes. The monthly GPS-derived second zonal coefficient closely resembles the SLR-derived and CSR RL04 values, and third and fourth zonal coefficients resemble the CSR RL04 values.

Using GRACE Satellite Gravimetry for Assessing Large-Scale Hydrologic Extremes

Directory of Open Access Journals (Sweden)

Alexander Y. Sun

2017-12-01

Full Text Available Global assessment of the spatiotemporal variability in terrestrial total water storage anomalies (TWSA in response to hydrologic extremes is critical for water resources management. Using TWSA derived from the gravity recovery and climate experiment (GRACE satellites, this study systematically assessed the skill of the TWSA-climatology (TC approach and breakpoint (BP detection method for identifying large-scale hydrologic extremes. The TC approach calculates standardized anomalies by using the mean and standard deviation of the GRACE TWSA corresponding to each month. In the BP detection method, the empirical mode decomposition (EMD is first applied to identify the mean return period of TWSA extremes, and then a statistical procedure is used to identify the actual occurrence times of abrupt changes (i.e., BPs in TWSA. Both detection methods were demonstrated on basin-averaged TWSA time series for the world’s 35 largest river basins. A nonlinear event coincidence analysis measure was applied to cross-examine abrupt changes detected by these methods with those detected by the Standardized Precipitation Index (SPI. Results show that our EMD-assisted BP procedure is a promising tool for identifying hydrologic extremes using GRACE TWSA data. Abrupt changes detected by the BP method coincide well with those of the SPI anomalies and with documented hydrologic extreme events. Event timings obtained by the TC method were ambiguous for a number of river basins studied, probably because the GRACE data length is too short to derive long-term climatology at this time. The BP approach demonstrates a robust wet-dry anomaly detection capability, which will be important for applications with the upcoming GRACE Follow-On mission.

Global evaluation of new GRACE mascon products for hydrologic applications

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Scanlon, Bridget R.; Zhang, Zizhan; Save, Himanshu; Wiese, David N.; Landerer, Felix W.; Long, Di; Longuevergne, Laurent; Chen, Jianli

2016-12-01

Recent developments in mascon (mass concentration) solutions for GRACE (Gravity Recovery and Climate Experiment) satellite data have significantly increased the spatial localization and amplitude of recovered terrestrial Total Water Storage anomalies (TWSA); however, land hydrology applications have been limited. Here we compare TWSA from April 2002 through March 2015 from (1) newly released GRACE mascons from the Center for Space Research (CSR-M) with (2) NASA JPL mascons (JPL-M), and with (3) CSR Tellus gridded spherical harmonics rescaled (sf) (CSRT-GSH.sf) in 176 river basins, ˜60% of the global land area. Time series in TWSA mascons (CSR-M and JPL-M) and spherical harmonics are highly correlated (rank correlation coefficients mostly >0.9). The signal from long-term trends (up to ±20 mm/yr) is much less than that from seasonal amplitudes (up to 250 mm). Net long-term trends, summed over all 176 basins, are similar for CSR and JPL mascons (66-69 km3/yr) but are lower for spherical harmonics (˜14 km3/yr). Long-term TWSA declines are found mostly in irrigated basins (-41 to -69 km3/yr). Seasonal amplitudes agree among GRACE solutions, increasing confidence in GRACE-based seasonal fluctuations. Rescaling spherical harmonics significantly increases agreement with mascons for seasonal fluctuations, but less for long-term trends. Mascons provide advantages relative to spherical harmonics, including (1) reduced leakage from land to ocean increasing signal amplitude, and (2) application of geophysical data constraints during processing with little empirical postprocessing requirements, making it easier for nongeodetic users. Results of this product intercomparison should allow hydrologists to better select suitable GRACE solutions for hydrologic applications.

Dynamics of the Antarctic Circumpolar Current as seen by GRACE (Invited)

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Thomas, M.; Dobslaw, H.; Bergmann, I.

2010-12-01

The Antarctic Circumpolar Current, being the strongest and longest ocean current on Earth, connects the three great ocean basins and contributes substantially to the global re-distribution of water masses, with a significant impact on global climate. Observational coverage from in-situ measurements is sparse due to the harsh environmental conditions, and satellite altimetry does not capture the full extent of the current due to seasonal sea-ice coverage. Ocean bottom pressure variations as sensed with the satellite gravity mission GRACE provide a promising way to broaden our observational basis. Besides monthly mean gravity fields that provide ocean bottom pressure variations averaged over 30 days, several alternative GRACE products with higher temporal resolution have been developed during the most recent years. These include 10-day solutions from GRGS Toulouse, weekly solutions from the GFZ Potsdam as well as constrained daily solutions from the University of Bonn which have been obtained by means of a Kalman filtering approach. In this presentation, ocean bottom pressure derived from these alternative GRACE releases will be contrasted against both in-situ observations and output from a numerical ocean model, highlighting the additional information contained in these GRACE solutions with respect to the standard monthly fields. By means of statistical analyses of ocean bottom pressure variations and barotropic transports it will be demonstrated how these new GRACE releases are contributing to our understanding of this highly dynamic great ocean conveyor.

Measuring Earth: Current status of the GRACE Follow-On Laser Ranging Interferometer

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Schütze, Daniel; LRI Team

2016-05-01

The GRACE mission that was launched in 2002 has impressively proven the feasibility of low-orbit satellite-to-satellite tracking for Earth gravity observations. Especially mass transport related to Earth's hydrological system could be well resolved both spatially and temporally. This allows to study processes such as polar ice sheet decline and ground water depletion in great detail. Owing to GRACE's success, NASA and GFZ will launch the successor mission GRACE Follow-On in 2017. In addition to the microwave ranging system, GRACE Follow-On will be the first mission to use a Laser Ranging Interferometer as technology demonstrator to track intersatellite distance changes with unprecedented precision. This new ranging device inherits some of the technologies which have been developed for the future spaceborne gravitational wave detector LISA. I will present the architecture of the Laser Ranging Interferometer, point out similarities and differences to LISA, and conclude with the current status of the flight hardware production.

Grace Murray Hopper - Programming Pioneer

Indian Academy of Sciences (India)

Home; Journals; Resonance – Journal of Science Education; Volume 6; Issue 2. Grace Murray Hopper - Programming Pioneer. V Rajaraman. Article-in-a-Box Volume 6 Issue 2 February 2001 pp 2-3. Fulltext. Click here to view fulltext PDF. Permanent link: https://www.ias.ac.in/article/fulltext/reso/006/02/0002-0003 ...

Eficiencia del proceso de devoluciones al contribuyente que realiza la DIAN para el año 2007

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Fernando Cruz Montoya

2009-12-01

Full Text Available Con el fin de contribuir al fortalecimiento de la seguridad jurídica del contribuyente en Colombia, se presentan los principales resultados de un estudio que pretendía evaluar el cumplimiento de principios constitucionales (como la igualdad, economía, celeridad, eficiencia, transparencia e imparcialidad en los procesos tributarios de devolución efectuados por la Dirección de Impuestos y Aduanas Nacionales, DIAN. Esto enfocado a los impuestos de renta e IVA durante el 2007 en la ciudad de Cali.

Quantitative Amyloid Imaging in Autosomal Dominant Alzheimer’s Disease: Results from the DIAN Study Group

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Su, Yi; Blazey, Tyler M.; Owen, Christopher J.; Christensen, Jon J.; Friedrichsen, Karl; Joseph-Mathurin, Nelly; Wang, Qing; Hornbeck, Russ C.; Ances, Beau M.; Snyder, Abraham Z.; Cash, Lisa A.; Koeppe, Robert A.; Klunk, William E.; Galasko, Douglas; Brickman, Adam M.; McDade, Eric; Ringman, John M.; Thompson, Paul M.; Saykin, Andrew J.; Ghetti, Bernardino; Sperling, Reisa A.; Johnson, Keith A.; Salloway, Stephen P.; Schofield, Peter R.; Masters, Colin L.; Villemagne, Victor L.; Fox, Nick C.; Förster, Stefan; Chen, Kewei; Reiman, Eric M.; Xiong, Chengjie; Marcus, Daniel S.; Weiner, Michael W.; Morris, John C.; Bateman, Randall J.; Benzinger, Tammie L. S.

2016-01-01

Amyloid imaging plays an important role in the research and diagnosis of dementing disorders. Substantial variation in quantitative methods to measure brain amyloid burden exists in the field. The aim of this work is to investigate the impact of methodological variations to the quantification of amyloid burden using data from the Dominantly Inherited Alzheimer’s Network (DIAN), an autosomal dominant Alzheimer’s disease population. Cross-sectional and longitudinal [11C]-Pittsburgh Compound B (PiB) PET imaging data from the DIAN study were analyzed. Four candidate reference regions were investigated for estimation of brain amyloid burden. A regional spread function based technique was also investigated for the correction of partial volume effects. Cerebellar cortex, brain-stem, and white matter regions all had stable tracer retention during the course of disease. Partial volume correction consistently improves sensitivity to group differences and longitudinal changes over time. White matter referencing improved statistical power in the detecting longitudinal changes in relative tracer retention; however, the reason for this improvement is unclear and requires further investigation. Full dynamic acquisition and kinetic modeling improved statistical power although it may add cost and time. Several technical variations to amyloid burden quantification were examined in this study. Partial volume correction emerged as the strategy that most consistently improved statistical power for the detection of both longitudinal changes and across-group differences. For the autosomal dominant Alzheimer’s disease population with PiB imaging, utilizing brainstem as a reference region with partial volume correction may be optimal for current interventional trials. Further investigation of technical issues in quantitative amyloid imaging in different study populations using different amyloid imaging tracers is warranted. PMID:27010959

Temperature corrected-calibration of GRACE's accelerometer

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Encarnacao, J.; Save, H.; Siemes, C.; Doornbos, E.; Tapley, B. D.

2017-12-01

Since April 2011, the thermal control of the accelerometers on board the GRACE satellites has been turned off. The time series of along-track bias clearly show a drastic change in the behaviour of this parameter, while the calibration model has remained unchanged throughout the entire mission lifetime. In an effort to improve the quality of the gravity field models produced at CSR in future mission-long re-processing of GRACE data, we quantify the added value of different calibration strategies. In one approach, the temperature effects that distort the raw accelerometer measurements collected without thermal control are corrected considering the housekeeping temperature readings. In this way, one single calibration strategy can be consistently applied during the whole mission lifetime, since it is valid to thermal the conditions before and after April 2011. Finally, we illustrate that the resulting calibrated accelerations are suitable for neutral thermospheric density studies.

Regional GRACE-based estimates of water mass variations over Australia: validation and interpretation

Science.gov (United States)

Seoane, L.; Ramillien, G.; Frappart, F.; Leblanc, M.

2013-04-01

Time series of regional 2°-by-2° GRACE solutions have been computed from 2003 to 2011 with a 10 day resolution by using an energy integral method over Australia [112° E 156° E; 44° S 10° S]. This approach uses the dynamical orbit analysis of GRACE Level 1 measurements, and specially accurate along-track K Band Range Rate (KBRR) residuals (1 μm s-1 level of error) to estimate the total water mass over continental regions. The advantages of regional solutions are a significant reduction of GRACE aliasing errors (i.e. north-south stripes) providing a more accurate estimation of water mass balance for hydrological applications. In this paper, the validation of these regional solutions over Australia is presented as well as their ability to describe water mass change as a reponse of climate forcings such as El Niño. Principal component analysis of GRACE-derived total water storage maps show spatial and temporal patterns that are consistent with independent datasets (e.g. rainfall, climate index and in-situ observations). Regional TWS show higher spatial correlations with in-situ water table measurements over Murray-Darling drainage basin (80-90%), and they offer a better localization of hydrological structures than classical GRACE global solutions (i.e. Level 2 GRGS products and 400 km ICA solutions as a linear combination of GFZ, CSR and JPL GRACE solutions).

Inter-comparison of GRACE data over India

Science.gov (United States)

Banerjee, Chandan; Kumar, D. Nagesh

2016-05-01

The advent of satellite remote sensing and its use in hydrology has facilitated a huge leap in the understanding of the various water resources, its interaction with ecological systems and anthropogenic creations. Recently, NASA and German Aerospace Research Agency-DLR launched the Gravity Recovery and Climate Experiment (GRACE) satellite mission consisting of two satellites. They measure the time varying gravity which gives changes in the distribution of mass on the surface of the earth which after removing atmospheric and oceanic effects is majorly caused by changes in Terrestrial Water Storage (TWS) changes. GRACE data is generally available as spherical harmonic coefficients, which is difficult for hydrologists to understand and interpret. JPL's TELLUS website is now providing gridded global data set in the form of mass anomaly derived from the Level-2 data sets of spherical harmonic coefficients of 3 sources, viz. CSR, GFZ and JPL. Before using these data sets for solving hydrological problems, it is important to understand the differences and similarities between these data sets as direct calibration of GRACE data is not possible. In this study we do an inter-comparison of the Level-3 Release 05 data sets over India. We compare the data sets using Pearson, Spearman and Kendall correlation. CSR and GFZ data sets appear to be closest to each other whereas JPL and GFZ data sets are most different from each other.

Using Tikhonov Regularization for Spatial Projections from CSR Regularized Spherical Harmonic GRACE Solutions

Science.gov (United States)

Save, H.; Bettadpur, S. V.

2013-12-01

It has been demonstrated before that using Tikhonov regularization produces spherical harmonic solutions from GRACE that have very little residual stripes while capturing all the signal observed by GRACE within the noise level. This paper demonstrates a two-step process and uses Tikhonov regularization to remove the residual stripes in the CSR regularized spherical harmonic coefficients when computing the spatial projections. We discuss methods to produce mass anomaly grids that have no stripe features while satisfying the necessary condition of capturing all observed signal within the GRACE noise level.

Book review: Diane Ravitch "The death and life of the great American school system". New York: Basic Books , 2010

Directory of Open Access Journals (Sweden)

Beals K.

2015-09-01

Full Text Available The current paper is a translation of Katharine Beals' review of the book "The death and life of the great American school system" by Diane Ravich. The article analyses the views on the causes of the inefficiency of the American school system expressed by Ravich, as well as the ways of its improvement suggested by her. A change of stance compared to her previous works is also noted. Translator: Vinogradova K.N.

LA AUTONOMÍA DE LA PERSONA FRENTE AL DERECHO A LA VIDA NO INCLUYE EL DERECHO A SER MUERTO POR UN TERCERO: LA SOLICITUD DE ASISTENCIA AL SUICIDIO Y EL CASO DE DIANE PRETTY A AUTONOMIA DA PESSOA FRENTE AO DIREITO À VIDA NÃO INCLUI O DIREITO A SER MORTO POR UM TERCEIRO: A SOLICITAÇÃO AO SUICÍDIO ASSISTIDO E O CASO DE DIANE PRETTY A PERSON'S AUTONOMY VIS-À-VIS THE RIGHT TO LIFE DOES NOT INCLUDE THE RIGHT TO BE KILLED BY A THIRD PERSON: ASSISTANCE REQUEST TO COMMIT SUICIDE AND DIANE PRETTY'S CASE

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Ángela Vivanco Martínez

2002-01-01

Full Text Available La autora, en la presente monografía, analiza las resoluciones pronunciadas por la House of Lords y por la Corte Europea de Derechos Humanos en el caso de Diane Pretty, ciudadana inglesa fallecida en mayo de 2002 quien, a causa de una enfermedad degenerativa e incurable, pretendió se reconociera inmunidad a su marido en caso de prestarle asistencia para suicidarse. Los fallos examinados rechazaron la solicitud de la recurrenteNa presente monografia a autora analisa as decisões emanadas pela Câmara do Lordes e Corte Européia de Direitos Humanos no caso Diane Pretty, cidadã inglesa falecida em maio de 2002 que em decorrência de enfermidade degenerativa incurável, pretendeu fosse reconhecida imunidade a seu marido para que a auxiliasse a suicidarse. As decisões recusaram a solicitação da recorrenteThe author of this monograph analyses the resolutions pronounced by the House of Lords and by the European Court of Human Rights in the case of Diane Pretty, an English citizen who died in may 2002. Because of a degenerative and incurable disease she pretended her husband be granted immunity if he helped her to commit suicide. The verdicts which were examined rejected her request

Radial and tangential gravity rates from GRACE in areas of glacial isostatic adjustment

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van der Wal, Wouter; Kurtenbach, Enrico; Kusche, Jürgen; Vermeersen, Bert

2011-11-01

In areas dominated by Glacial Isostatic Adjustment (GIA), the free-air gravity anomaly rate can be converted to uplift rate to good approximation by using a simple spectral relation. We provide quantitative comparisons between gravity rates derived from monthly gravity field solutions (GFZ Potsdam, CSR Texas, IGG Bonn) from the Gravity Recovery and Climate Experiment (GRACE) satellite mission with uplift rates measured by GPS in these areas. The band-limited gravity data from the GRACE satellite mission can be brought to very good agreement with the point data from GPS by using scaling factors derived from a GIA model (the root-mean-square of differences is 0.55 mm yr-1 for a maximum uplift rate signal of 10 mm yr-1). The root-mean-square of the differences between GRACE derived uplift rates and GPS derived uplift rates decreases with increasing GRACE time period to a level below the uncertainty that is expected from GRACE observations, GPS measurements and the conversion from gravity rate to uplift rate. With the current length of time-series (more than 8 yr) applying filters and a hydrology correction to the GRACE data does not reduce the root-mean-square of differences significantly. The smallest root-mean-square was obtained with the GFZ solution in Fennoscandia and with the CSR solution in North America. With radial gravity rates in excellent agreement with GPS uplift rates, more information on the GIA process can be extracted from GRACE gravity field solutions in the form of tangential gravity rates, which are equivalent to a rate of change in the deflection of the vertical scaled by the magnitude of gravity rate vector. Tangential gravity rates derived from GRACE point towards the centre of the previously glaciated area, and are largest in a location close to the centre of the former ice sheet. Forward modelling showed that present day tangential gravity rates have maximum sensitivity between the centre and edge of the former ice sheet, while radial gravity

Preliminary Results from Powell Research Group on Integrating GRACE Satellite and Ground-based Estimates of Groundwater Storage Changes

Science.gov (United States)

Scanlon, B. R.; Zhang, Z.; Reitz, M.; Rodell, M.; Sanford, W. E.; Save, H.; Wiese, D. N.; Croteau, M. J.; McGuire, V. L.; Pool, D. R.; Faunt, C. C.; Zell, W.

2017-12-01

Groundwater storage depletion is a critical issue for many of the major aquifers in the U.S., particularly during intense droughts. GRACE (Gravity Recovery and Climate Experiment) satellite-based estimates of groundwater storage changes have attracted considerable media attention in the U.S. and globally and interest in GRACE products continues to increase. For this reason, a Powell Research Group was formed to: (1) Assess variations in groundwater storage using a variety of GRACE products and other storage components (snow, surface water, and soil moisture) for major aquifers in the U.S., (2) Quantify long-term trends in groundwater storage from ground-based monitoring and regional and national modeling, and (3) Use ground-based monitoring and modeling to interpret GRACE water storage changes within the context of extreme droughts and over-exploitation of groundwater. The group now has preliminary estimates from long-term trends and seasonal fluctuations in water storage using different GRACE solutions, including CSR, JPL and GSFC. Approaches to quantifying uncertainties in GRACE data are included. This work also shows how GRACE sees groundwater depletion in unconfined versus confined aquifers, and plans for future work will link GRACE data to regional groundwater models. The wealth of ground-based observations for the U.S. provides a unique opportunity to assess the reliability of GRACE-based estimates of groundwater storage changes.

Restored Plasma Anandamide and Endometrial Expression of Fatty Acid Amide Hydrolase in Women With Polycystic Ovary Syndrome by the Combination Use of Diane-35 and Metformin.

Science.gov (United States)

Cui, Na; Feng, Xiaoye; Zhao, Zhiming; Zhang, Jie; Xu, Yueming; Wang, Luning; Hao, Guimin

2017-04-01

Polycystic ovary syndrome (PCOS) is a metabolic and endocrinal disorder affecting a number of women of reproductive age. We aimed to reveal the correlation between the endocannabinoid system and PCOS, which may provide a new therapeutic target for PCOS treatment. Serum levels of anandamide and 2-arachidonoylglycerol andexpression of cannabinoid receptors and fatty acid amide hydrolase (FAAH) in the endometrium were compared between women with PCOS and infertile women without PCOS, as well as women with PCOS before and after treatment with Diane-35 and metformin. Cannabinoid receptors and FAAH in the endometrium were stained using the immunohistochemical method. Results were analyzed by calculating integrated optical density. Plasma anandamide was increased significantly in women with PCOS compared with infertile women without PCOS. Treatment with Diane-35 and metformin reversed this increase in women with PCOS. No significant difference in 2-arachidonoylglycerol was observed between the infertile women with or without PCOS. The women with PCOS had lower endometrial expression of FAAH compared with infertile women without PCOS, whereas no significant difference in endometrial expression of cannabinoid receptors was observed between the women with PCOS and infertile women without PCOS. We found that after treatment with Diane-35 and metformin, FAAH expression tended toward a significant increase compared with women before the treatment. Endocannabinoid system may be involved in the progression of PCOS, and serum anandamide could serve as a potential biomarker of clinical diagnosis of PCOS. Copyright © 2017 Elsevier HS Journals, Inc. All rights reserved.

Insights about data assimilation frameworks for integrating GRACE with hydrological models

Science.gov (United States)

Schumacher, Maike; Kusche, Jürgen; Van Dijk, Albert I. J. M.; Döll, Petra; Schuh, Wolf-Dieter

2016-04-01

Improving the understanding of changes in the water cycle represents a challenging objective that requires merging information from various disciplines. Debates exist on selecting an appropriate assimilation technique to integrate GRACE-derived terrestrial water storage changes (TWSC) into hydrological models in order to downscale and disaggregate GRACE TWSC, overcome model limitations, and improve monitoring and forecast skills. Yet, the effect of the specific data assimilation technique in conjunction with ill-conditioning, colored noise, resolution mismatch between GRACE and model, and other complications is still unclear. Due to its simplicity, ensemble Kalman filters or smoothers (EnKF/S) are often applied. In this study, we show that modification of the filter approach might open new avenues to improve the integration process. Particularly, we discuss an improved calibration and data assimilation (C/DA) framework (Schumacher et al., 2016), which is based on the EnKF and was extended by the square root analysis scheme (SQRA) and the singular evolutive interpolated Kalman (SEIK) filter. In addition, we discuss an off-line data blending approach (Van Dijk et al., 2014) that offers the chance to merge multi-model ensembles with GRACE observations. The investigations include: (i) a theoretical comparison, focusing on similarities and differences of the conceptual formulation of the filter algorithms, (ii) a practical comparison, for which the approaches were applied to an ensemble of runs of the WaterGAP Global Hydrology Model (WGHM), as well as (iii) an impact assessment of the GRACE error structure on C/DA results. First, a synthetic experiment over the Mississippi River Basin (USA) was used to gain insights about the C/DA set-up before applying it to real data. The results indicated promising performances when considering alternative methods, e.g. applying the SEIK algorithm improved the correlation coefficient and root mean square error (RMSE) of TWSC by 0

GRACE, time-varying gravity, Earth system dynamics and climate change

Science.gov (United States)

Wouters, B.; Bonin, J. A.; Chambers, D. P.; Riva, R. E. M.; Sasgen, I.; Wahr, J.

2014-11-01

Continuous observations of temporal variations in the Earth's gravity field have recently become available at an unprecedented resolution of a few hundreds of kilometers. The gravity field is a product of the Earth's mass distribution, and these data—provided by the satellites of the Gravity Recovery And Climate Experiment (GRACE)—can be used to study the exchange of mass both within the Earth and at its surface. Since the launch of the mission in 2002, GRACE data has evolved from being an experimental measurement needing validation from ground truth, to a respected tool for Earth scientists representing a fixed bound on the total change and is now an important tool to help unravel the complex dynamics of the Earth system and climate change. In this review, we present the mission concept and its theoretical background, discuss the data and give an overview of the major advances GRACE has provided in Earth science, with a focus on hydrology, solid Earth sciences, glaciology and oceanography.

ITSG-Grace2016 data preprocessing methodologies revisited: impact of using Level-1A data products

Science.gov (United States)

Klinger, Beate; Mayer-Gürr, Torsten

2017-04-01

For the ITSG-Grace2016 release, the gravity field recovery is based on the use of official GRACE (Gravity Recovery and Climate Experiment) Level-1B data products, generated by the Jet Propulsion Laboratory (JPL). Before gravity field recovery, the Level-1B instrument data are preprocessed. This data preprocessing step includes the combination of Level-1B star camera (SCA1B) and angular acceleration (ACC1B) data for an improved attitude determination (sensor fusion), instrument data screening and ACC1B data calibration. Based on a Level-1A test dataset, provided for individual month throughout the GRACE period by the Center of Space Research at the University of Texas at Austin (UTCSR), the impact of using Level-1A instead of Level-1B data products within the ITSG-Grace2016 processing chain is analyzed. We discuss (1) the attitude determination through an optimal combination of SCA1A and ACC1A data using our sensor fusion approach, (2) the impact of the new attitude product on temporal gravity field solutions, and (3) possible benefits of using Level-1A data for instrument data screening and calibration. As the GRACE mission is currently reaching its end-of-life, the presented work aims not only at a better understanding of GRACE science data to reduce the impact of possible error sources on the gravity field recovery, but it also aims at preparing Level-1A data handling capabilities for the GRACE Follow-On mission.

[Management of NSTEMI in a hospital without interventional cardiology and without use of GRACE score: Does the clinician appreciation match the GRACE score calculated retrospectively for the coronarography delay?

Science.gov (United States)

Bouriche, F; Yvorra, S; Hassan, A; Paganelli, F; Bonello, L; Luigi, S; Attia, F

2017-11-01

The management of non-ST segment elevation acute coronary syndromes (NSTEACS) remains an issue for mobidity, mortality, and an economic stake. The first aim of the study was to evaluate the additional value of the GRACE score for the compliance with the recommended times to coronary angiography in an hospital without interventional cardiology. We also analysed the in-hospital and 6-month mortality and the predictive factors of compliance for the coronarography delays. Retrospective monocenter cross-sectional study including consecutive patients with chest pain suggestive of a NSTEACS during 1 year. Data of the delay to coronarography were collected and GRACE score was calculated a posteriori. The time to perform coronary angiography was non-compliant in 49% of cases (27 patients out of 55). The calculation of the GRACE score would have allowed correcting the delay for two patients of our cohort. Clinical appreciation, troponin elevation, ECG modifications were associated with the delay compliance. Age <75 years predisposed to recommended delays. Renal failure and history of coronaropathy were significantly associated with non compliant delays. A non-compliant delay was significantly associated with higher mortality. In our experience, the knowledge of the GRACE score had little impact on the timing of coronary angiography. However, as a predictor of mid and long term mortality, GRACE score remains SCA ST+ useful to intensify surveillance of high-risk patients. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Clinical efficacy of low dose flutamide plus Diane-35 in the treatment of idiopathic hirsutism and polycystic ovary syndrome.

Science.gov (United States)

Boztosun, Abdullah; Açmaz, Gökhan; Ozturk, Ahmet; Müderris, Iptisam Ipek

2013-04-01

Idiopathic hirsutism (IH) or polycystic ovary syndrome (PCOS) are the most common causes of hirsutism which affects 5-10% of all women. The aim of this study was to evaluate the efficacy of flutamide plus diane 35 in the treatment of idiopathic hirsutism and polycystic ovary syndrome. 26 polycystic ovary syndrome and 24 idiopathic hirsutism patients were evaluated. Fifty patients were divided into two groups according to their diagnosis: idiopathic hirsutism or polycystic ovary syndrome. All patients received 125 mg Flutamide once a day and Diane 35 tablets for 21 days of each month, for 12 months. We measured hirsutism scores and hormonal levels of all patients. Evaluations were done before treatment, in the 6th and 12th months of therapy. There were no significant differences in Ferriman-Gallwey scores at the beginning and at the end of the therapy between the IH and PCOS groups. The decreases in Ferriman-Gallwey scores were significant in both groups in the 6th and 12th month of therapy. Combined treatment significantly decreased total and free testosterone, DHEAS and significantly increased SHBG levels in both groups and additionally decreased levels of LH, androstenodione and LH/FSH ratio in the polycystic ovary syndrome group. Combined treatment was effective and safe in the treatment of hirsutism. Combined regimens have additional effects on the treatment of hirsutism.

A Revolutionary Promise of Justice: Diane Arbus’ Self-Portrait, Pregnant, 1945, NYC

Directory of Open Access Journals (Sweden)

Andrea Liss

2017-08-01

Full Text Available My critical musings on this little-known maternal self-portrait are meant to reconceive its meaning as an uncanny predecessor to contemporary feminist embodied knowledge. This knowledge holds the potential for articulating new strategies of respect for the maternal and for the real mother, in other words for thinking m(otherwise. This portent photograph not only presented a non-normative concept of pregnancy during its cultural moment; it continues to challenge the deep patriarchal “embarrassment” that pregnancy carries. Arbus’ performance of the maternal was crafted within her creative practice and deeply embedded within a new maternal structure of projected work and self. Picturing herself as artist/photographer, other, lover and projected mother, she embodies a creative interplay between the passion of theory and the thinking body.   This photograph can be viewed at https://onlineonly.christies.com/s/photographs-diane-arbus/self-portrait-pregnant-n-y-c-1945-1/222.

PENGEMBANGAN PLATFORM KOMUNIKASI INSTANT UNTUK MENDUKUNG COLABORATIVE LEARNING PADA UNIVERSITAS DIAN NUSWANTORO

Directory of Open Access Journals (Sweden)

Fahri Firdausillah

2015-10-01

Full Text Available Instant messaging (IM atau chatting merupakan aplikasi internet yang memungkinkan penggunanya saling berkomunikasi melalui pesan teks, audio, maupun video secara langsung. Keunggulan IM yang memungkinkan pengguna berinteraksi secara langsung berpotensi untuk diterapkan dalam pengembangan sebuah metode pembelajaran kolaboratif di Universitas Dian Nuswantoro (UDINUS. Sistem informasi akademik (SiAdin merupakan aplikasi berbasis web yang membantu manajemen administratif dan edukatif pada UDINUS yang memungkinkan mahasiswa, dosen maupun staff yang lain untuk saling bertukar informasi serta kebutuhan akademik. Namun, hingga kini, SiAdin masih belum terintegrasi dengan platform komunikasi instan apapun.Meskipun layanan broadcast pesan telah diterapkan, namun pengguna harus membuat group secara manual, kemudian menambahkan anggota group secara manual terlebih dahulu. Hal ini menjadikan proses komunikasi kolaboratif jadi kurang optimal.Dalam penelitian ini, penulis mengusulkan menerapkan metode Computer-supported collaborative learning (CSCL di UDINUS dengan memanfaatkan SiAdin yang telah berjalan di UDINUS untuk mendukung berjalannya collaborative learning. Kata Kunci: Instant Messaging, SiAdin, Pembelajaran Kolaboratif.

Comparison of precision orbit derived density estimates for CHAMP and GRACE satellites

Science.gov (United States)

Fattig, Eric Dale

Current atmospheric density models cannot adequately represent the density variations observed by satellites in Low Earth Orbit (LEO). Using an optimal orbit determination process, precision orbit ephemerides (POE) are used as measurement data to generate corrections to density values obtained from existing atmospheric models. Densities obtained using these corrections are then compared to density data derived from the onboard accelerometers of satellites, specifically the CHAMP and GRACE satellites. This comparison takes two forms, cross correlation analysis and root mean square analysis. The densities obtained from the POE method are nearly always superior to the empirical models, both in matching the trends observed by the accelerometer (cross correlation), and the magnitudes of the accelerometer derived density (root mean square). In addition, this method consistently produces better results than those achieved by the High Accuracy Satellite Drag Model (HASDM). For satellites orbiting Earth that pass through Earth's upper atmosphere, drag is the primary source of uncertainty in orbit determination and prediction. Variations in density, which are often not modeled or are inaccurately modeled, cause difficulty in properly calculating the drag acting on a satellite. These density variations are the result of many factors; however, the Sun is the main driver in upper atmospheric density changes. The Sun influences the densities in Earth's atmosphere through solar heating of the atmosphere, as well as through geomagnetic heating resulting from the solar wind. Data are examined for fourteen hour time spans between November 2004 and July 2009 for both the CHAMP and GRACE satellites. This data spans all available levels of solar and geomagnetic activity, which does not include data in the elevated and high solar activity bins due to the nature of the solar cycle. Density solutions are generated from corrections to five different baseline atmospheric models, as well as

Time-variations of the regional evapotranspiration rate from GRACE satellite gravimetry

OpenAIRE

Ramillien , Guillaume; Frappart , Frédéric; Güntner , Andreas; Ngo-Duc , Thanh; Cazenave , Anny; Laval , Katia

2006-01-01

International audience; Since its launch in March 2002, the GRACE mission is measuring the global time variations of the Earth's gravity field with a current resolution of ~500 km. Especially over the continents, these measurements represent the integrated land water mass including surface waters (lakes, wetlands and rivers), soil moisture, groundwater and snow cover. In this study, we use the GRACE land water solutions computed by Ramillien et al. (2005a) through an iterative inversion of mo...

Signal and noise in Gravity Recovery and Climate Experiment (GRACE) observed surface mass variations

NARCIS (Netherlands)

Schrama, E.J.O.; Wouters, B.; Lavallée, D.A.

2007-01-01

The Gravity Recovery and Climate Experiment (GRACE) product used for this study consists of 43 monthly potential coefficient sets released by the GRACE science team which are used to generate surface mass thickness grids expressed as equivalent water heights (EQWHs). We optimized both the smoothing

Groundwater storage changes in arctic permafrost watersheds from GRACE and in situ measurements

International Nuclear Information System (INIS)

Muskett, Reginald R; Romanovsky, Vladimir E

2009-01-01

The Arctic permafrost regions make up the largest area component of the cryosphere. Observations from the Gravity Recovery and Climate Experiment (GRACE) mission offer to provide a greater understanding of changes in water mass within permafrost regions. We investigate a GRACE monthly time series, snow water equivalent from the special scanning microwave imager (SSM/I), vegetation water content and soil moisture from the advanced microwave scanning radiometer for the Earth observation system (AMSR-E) and in situ discharge of the Lena, Yenisei, Ob', and Mackenzie watersheds. The GRACE water equivalent mass change responded to mass loading by snow accumulation in winter and mass unloading by runoff in spring-summer. Comparison of secular trends from GRACE to runoff suggests groundwater storage increased in the Lena and Yenisei watersheds, decreased in the Mackenzie watershed, and was unchanged in the Ob' watershed. We hypothesize that the groundwater storage changes are linked to the development of closed- and open-talik in the continuous permafrost zone and the decrease of permafrost lateral extent in the discontinuous permafrost zone of the watersheds.

Separation of GRACE geoid time-variations using Independent Component Analysis

Science.gov (United States)

Frappart, F.; Ramillien, G.; Maisongrande, P.; Bonnet, M.

2009-12-01

Independent Component Analysis (ICA) is a blind separation method based on the simple assumptions of the independence of the sources and the non-Gaussianity of the observations. An approach based on this numerical method is used here to extract hydrological signals over land and oceans from the polluting striping noise due to orbit repetitiveness and present in the GRACE global mass anomalies. We took advantage of the availability of monthly Level-2 solutions from three official providers (i.e., CSR, JPL and GFZ) that can be considered as different observations of the same phenomenon. The efficiency of the methodology is first demonstrated on a synthetic case. Applied to one month of GRACE solutions, it allows to clearly separate the total water storage change from the meridional-oriented spurious gravity signals on the continents but not on the oceans. This technique gives results equivalent as the destriping method for continental water storage for the hydrological patterns with less smoothing. This methodology is then used to filter the complete series of the 2002-2009 GRACE solutions.

GRACE, time-varying gravity, Earth system dynamics and climate change

International Nuclear Information System (INIS)

Wouters, B; Bonin, J A; Chambers, D P; Riva, R E M; Sasgen, I; Wahr, J

2014-01-01

Continuous observations of temporal variations in the Earth's gravity field have recently become available at an unprecedented resolution of a few hundreds of kilometers. The gravity field is a product of the Earth's mass distribution, and these data—provided by the satellites of the Gravity Recovery And Climate Experiment (GRACE)—can be used to study the exchange of mass both within the Earth and at its surface. Since the launch of the mission in 2002, GRACE data has evolved from being an experimental measurement needing validation from ground truth, to a respected tool for Earth scientists representing a fixed bound on the total change and is now an important tool to help unravel the complex dynamics of the Earth system and climate change. In this review, we present the mission concept and its theoretical background, discuss the data and give an overview of the major advances GRACE has provided in Earth science, with a focus on hydrology, solid Earth sciences, glaciology and oceanography. (review article)

Glacial isostatic adjustment on the Northern Hemisphere - new results from GRACE

Science.gov (United States)

Mueller, J.; Steffen, H.; Gitlein, O.; Denker, H.; Timmen, L.

2007-12-01

The Earth's gravity field mapped by the Gravity Recovery and Climate Experiment (GRACE) satellite mission shows variations due to the integral effect of mass variations in the atmosphere, hydrosphere and geosphere. The Earth's gravity field is provided in form of monthly solutions by several institutions, e.~g. GFZ Potsdam, CSR and JPL. During the GRACE standard processing of these analysis centers, oceanic and atmospheric contributions as well as tidal effects are reduced. The solutions of the analysis centers differ slightly, which is due the application of different reduction models and center-specific processing schemes. We present our investigation of mass variations in the areas of glacial isostatic adjustment (GIA) in North America and Northern Europe from GRACE data. One key issue is the separation of GIA parts and the reduction of the observed quantities by applying dedicated filters (e.~g. isotropic, non-isotropic, and destriping filters) and global models of hydrological variations (e.~g. WGHM, LaDWorld, GLDAS). In a further step, we analyze the results of both regions regarding their reliability, and finally present a comparison to results of a geodynamical modeling and absolute gravity measurements. Our results clearly show that the quality of the GRACE-derived gravity- change signal benefits from improved reduction models and chosen analysis techniques. Nevertheless, the comparison to results of geodynamic models still reveals differences, and thus further studies are in progress.

Water balance of the Arctic drainage system using GRACE gravimetry products

OpenAIRE

Frappart, F; Ramillien, G; Famiglietti, JS

2011-01-01

International audience; Land water and snow mass anomalies versus time were computed from the inversion of 50 GRACE geoids (August 2002 to February 2007) from the RL04 GFZ release and used to characterize the hydrology of the Arctic drainage system. GRACE-based time series have been compared to snow water equivalent and snow depth climatologies, and snowfall for validation purpose. Time series of regional averages of water volume were estimated for the 11 largest Peri-Arctic basins. Strong co...

Sediment-Mass Accumulation Rate and Variability in the East China Sea Detected by GRACE

Directory of Open Access Journals (Sweden)

Ya-Chi Liu

2016-09-01

Full Text Available The East China Sea (ECS is a region with shallow continental shelves and a mixed oceanic circulation system allowing sediments to deposit on its inner shelf, particularly near the estuary of the Yangtze River. The seasonal northward-flowing Taiwan Warm Current and southward-flowing China Coastal Current trap sediments from the Yangtze River, which are accumulated over time at rates of up to a few mm/year in equivalent water height. Here, we use the Gravity Recovery and Climate Experiment (GRACE gravity products from three data centres to determine sediment mass accumulation rates (MARs and variability on the ECS inner shelf. We restore the atmospheric and oceanic effects to avoid model contaminations on gravity signals associated with sediment masses. We apply destriping and spatial filters to improve the gravity signals from GRACE and use the Global Land Data Assimilation System to reduce land leakage. The GRACE-derived MARs over April 2002–March 2015 on the ECS inner shelf are about 6 mm/year and have magnitudes and spatial patterns consistent with those from sediment-core measurements. The GRACE-derived monthly sediment depositions show variations at time scales ranging from six months to more than two years. Typically, a positive mass balance of sediment deposition occurs in late fall to early winter when the southward coastal currents prevail. A negative mass balance happens in summer when the coastal currents are northward. We identify quasi-biennial sediment variations, which are likely to be caused by quasi-biennial variations in rain and erosion in the Yangtze River basin. We briefly explain the mechanisms of such frequency-dependent variations in the GRACE-derived ECS sediment deposition. There is no clear perturbation on sediment deposition over the ECS inner shelf induced by the Three Gorges Dam. The limitations of GRACE in resolving sediment deposition are its low spatial resolution (about 250 km and possible contaminations by

A Feynman graph selection tool in GRACE system

International Nuclear Information System (INIS)

Yuasa, Fukuko; Ishikawa, Tadashi; Kaneko, Toshiaki

2001-01-01

We present a Feynman graph selection tool grcsel, which is an interpreter written in C language. In the framework of GRACE, it enables us to get a subset of Feynman graphs according to given conditions

A comparison of annual vertical crustal displacements from GPS and Gravity Recovery and Climate Experiment (GRACE) over Europe

Science.gov (United States)

van Dam, T.; Wahr, J.; LavalléE, David

2007-03-01

We compare approximately 3 years of GPS height residuals (with respect to the International Terrestrial Reference Frame) with predictions of vertical surface displacements derived from the Gravity Recovery and Climate Experiment (GRACE) gravity fields for stations in Europe. An annual signal fit to the residual monthly heights, corrected for atmospheric pressure and barotropic ocean loading effects, should primarily represent surface displacements due to long-wavelength variations in water storage. A comparison of the annual height signal from GPS and GRACE over Europe indicates that at most sites, the annual signals do not agree in amplitude or phase. We find that unlike the annual signal predicted from GRACE, the annual signal in the GPS heights is not coherent over the region, displaying significant variability from site to site. Confidence in the GRACE data and the unlikely possibility of large-amplitude small-scale features in the load field not captured by the GRACE data leads us to conclude that some of the discrepancy between the GPS and GRACE observations is due to technique errors in the GPS data processing. This is evidenced by the fact that the disagreement between GPS and GRACE is largest at coastal sites, where mismodeling of the semidiurnal ocean tidal loading signal can result in spurious annual signals.

Large scale mass redistribution and surface displacement from GRACE and SLR

Science.gov (United States)

Cheng, M.; Ries, J. C.; Tapley, B. D.

2012-12-01

Mass transport between the atmosphere, ocean and solid earth results in the temporal variations in the Earth gravity field and loading induced deformation of the Earth. Recent space-borne observations, such as GRACE mission, are providing extremely high precision temporal variations of gravity field. The results from 10-yr GRACE data has shown a significant annual variations of large scale vertical and horizontal displacements occurring over the Amazon, Himalayan region and South Asia, African, and Russian with a few mm amplitude. Improving understanding from monitoring and modeling of the large scale mass redistribution and the Earth's response are a critical for all studies in the geosciences, in particular for determination of Terrestrial Reference System (TRS), including geocenter motion. This paper will report results for the observed seasonal variations in the 3-dimentional surface displacements of SLR and GPS tracking stations and compare with the prediction from time series of GRACE monthly gravity solution.

GRace: a MATLAB-based application for fitting the discrimination-association model.

Science.gov (United States)

Stefanutti, Luca; Vianello, Michelangelo; Anselmi, Pasquale; Robusto, Egidio

2014-10-28

The Implicit Association Test (IAT) is a computerized two-choice discrimination task in which stimuli have to be categorized as belonging to target categories or attribute categories by pressing, as quickly and accurately as possible, one of two response keys. The discrimination association model has been recently proposed for the analysis of reaction time and accuracy of an individual respondent to the IAT. The model disentangles the influences of three qualitatively different components on the responses to the IAT: stimuli discrimination, automatic association, and termination criterion. The article presents General Race (GRace), a MATLAB-based application for fitting the discrimination association model to IAT data. GRace has been developed for Windows as a standalone application. It is user-friendly and does not require any programming experience. The use of GRace is illustrated on the data of a Coca Cola-Pepsi Cola IAT, and the results of the analysis are interpreted and discussed.

Comparison of observed and modeled seasonal crustal vertical displacements derived from multi-institution GPS and GRACE solutions

Science.gov (United States)

Gu, Yanchao; Fan, Dongming; You, Wei

2017-07-01

Eleven GPS crustal vertical displacement (CVD) solutions for 110 IGS08/IGS14 core stations provided by the International Global Navigation Satellite Systems Service Analysis Centers are compared with seven Gravity Recovery and Climate Experiment (GRACE)-modeled CVD solutions. The results of the internal comparison of the GPS solutions from multiple institutions imply large uncertainty in the GPS postprocessing. There is also evidence that GRACE solutions from both different institutions and different processing approaches (mascon and traditional spherical harmonic coefficients) show similar results, suggesting that GRACE can provide CVD results of good internal consistency. When the uncertainty of the GPS data is accounted for, the GRACE data can explain as much as 50% of the actual signals and more than 80% of the GPS annual signals. Our study strongly indicates that GRACE data have great potential to correct the nontidal loading in GPS time series.

Constraining Earth's Rheology of the Barents Sea Using Grace Gravity Change Observations

Science.gov (United States)

van der Wal, W.; Root, B. C.; Tarasov, L.

2014-12-01

The Barents Sea region was ice covered during last glacial maximum and experiences Glacial Isostatic Adjustment (GIA). Because of the limited amount of relevant geological and geodetic observations, it is difficult to constrain GIA models for this region. With improved ice sheet models and gravity observations from GRACE, it is possible to better constrain Earth rheology. This study aims to constrain the upper mantle viscosity and elastic lithosphere thickness from GRACE data in the Barents Sea region. The GRACE observations are corrected for current ice melting on Svalbard, Novaya Zemlya and Frans Joseph Land. A secular trend in gravity rate trend is estimated from the CSR release 5 GRACE data for the period of February 2003 to July 2013. Furthermore, long wavelength effects from distant large mass balance signals such as Greenland ice melting are filtered out. A new high-variance set of ice loading histories from calibrated glaciological modeling are used in the GIA modeling as it is found that ICE-5G over-estimates the observed GIA gravity change in the region. It is found that the rheology structure represented by VM5a results in over-estimation of the observed gravity change in the region for all ice sheet chronologies investigated. Therefore, other rheological Earth models were investigated. The best fitting upper mantle viscosity and elastic lithosphere thickness in the Barents Sea region are 4 (±0.5)*10^20 Pas and 110 (±20) km, respectively. The GRACE satellite mission proves to be a useful constraint in the Barents Sea Region for improving our knowledge on the upper mantle rheology.

Global models underestimate large decadal declining and rising water storage trends relative to GRACE satellite data

Science.gov (United States)

Scanlon, Bridget R.; Zhang, Zizhan; Save, Himanshu; Sun, Alexander Y.; van Beek, Ludovicus P. H.; Wiese, David N.; Reedy, Robert C.; Longuevergne, Laurent; Döll, Petra; Bierkens, Marc F. P.

2018-01-01

Assessing reliability of global models is critical because of increasing reliance on these models to address past and projected future climate and human stresses on global water resources. Here, we evaluate model reliability based on a comprehensive comparison of decadal trends (2002–2014) in land water storage from seven global models (WGHM, PCR-GLOBWB, GLDAS NOAH, MOSAIC, VIC, CLM, and CLSM) to trends from three Gravity Recovery and Climate Experiment (GRACE) satellite solutions in 186 river basins (∼60% of global land area). Medians of modeled basin water storage trends greatly underestimate GRACE-derived large decreasing (≤−0.5 km3/y) and increasing (≥0.5 km3/y) trends. Decreasing trends from GRACE are mostly related to human use (irrigation) and climate variations, whereas increasing trends reflect climate variations. For example, in the Amazon, GRACE estimates a large increasing trend of ∼43 km3/y, whereas most models estimate decreasing trends (−71 to 11 km3/y). Land water storage trends, summed over all basins, are positive for GRACE (∼71–82 km3/y) but negative for models (−450 to −12 km3/y), contributing opposing trends to global mean sea level change. Impacts of climate forcing on decadal land water storage trends exceed those of modeled human intervention by about a factor of 2. The model-GRACE comparison highlights potential areas of future model development, particularly simulated water storage. The inability of models to capture large decadal water storage trends based on GRACE indicates that model projections of climate and human-induced water storage changes may be underestimated. PMID:29358394

Homocysteine enhances the predictive value of the GRACE risk score in patients with ST-elevation myocardial infarction.

Science.gov (United States)

Fan, Yan; Wang, Jianjun; Zhang, Sumei; Wan, Zhaofei; Zhou, Dong; Ding, Yanhong; He, Qinli; Xie, Ping

2017-09-01

The present study aims to investigate whether the addition of homocysteine level to the Global Registry of Acute Coronary Events (GRACE) risk score enhances its predictive value for clinical outcomes in ST-elevation myocardial infarction (STEMI). A total of 1143 consecutive patients with STEMI were included in this prospective cohort study. Homocysteine was detected, and the GRACE score was calculated. The predictive power of the GRACE score alone or combined with homocysteine was assessed by the receiver operating characteristic (ROC) analysis, methods of net reclassification improvement (NRI) and integrated discrimination improvement (IDI). During a median follow-up period of 36.7 months, 271 (23.7%) patients reached the clinical endpoints. It showed that the GRACE score and homocysteine could independently predict all-cause death [GRACE: HR=1.031 (1.024-1.039), p<0.001; homocysteine: HR=1.023 (1.018-1.028), p<0.001] and MACE [GRACE: HR=1.008 (1.005-1.011), p<0.001; homocysteine: HR=1.022 (1.018-1.025), p<0.001]. When they were used in combination to assess the clinical outcomes, the area under the ROC curve significantly increased from 0.786 to 0.884 (95% CI=0.067-0.128, Z=6.307, p<0.001) for all-cause death and from 0.678 to 0.759 (95% CI=0.055-0.108, Z=5.943, p<0.001) for MACE. The addition of homocysteine to the GRACE model improved NRI (all-cause death: 0.575, p<0.001; MACE: 0.621, p=0.008) and IDI (all-cause death: 0.083, p<0.001; MACE: 0.130, p=0.016), indicating effective discrimination and reclassification. Both the GRACE score and homocysteine are significant and independent predictors for clinical outcomes in patients with STEMI. A combination of them can develop a more predominant prediction for clinical outcomes in these patients.

Measuring the Value of Earth Observation Information with the Gravity Research and Climate Experiment (GRACE) Satellite

Science.gov (United States)

Bernknopf, R.; Kuwayama, Y.; Brookshire, D.; Macauley, M.; Zaitchik, B.; Pesko, S.; Vail, P.

2014-12-01

Determining how much to invest in earth observation technology depends in part on the value of information (VOI) that can be derived from the observations. We design a framework and then evaluate the value-in-use of the NASA Gravity Research and Climate Experiment (GRACE) for regional water use and reliability in the presence of drought. As a technology that allows measurement of water storage, the GRACE Data Assimilation System (DAS) provides information that is qualitatively different from that generated by other water data sources. It provides a global, reproducible grid of changes in surface and subsurface water resources on a frequent and regular basis. Major damages from recent events such as the 2012 Midwest drought and the ongoing drought in California motivate the need to understand the VOI from remotely sensed data such as that derived from GRACE DAS. Our conceptual framework models a dynamic risk management problem in agriculture. We base the framework on information from stakeholders and subject experts. The economic case for GRACE DAS involves providing better water availability information. In the model, individuals have a "willingness to pay" (wtp) for GRACE DAS - essentially, wtp is an expression of savings in reduced agricultural input costs and for costs that are influenced by regional policy decisions. Our hypothesis is that improvements in decision making can be achieved with GRACE DAS measurements of water storage relative to data collected from groundwater monitoring wells and soil moisture monitors that would be relied on in the absence of GRACE DAS. The VOI is estimated as a comparison of outcomes. The California wine grape industry has features that allow it to be a good case study and a basis for extrapolation to other economic sectors. We model water use in this sector as a sequential decision highlighting the attributes of GRACE DAS input as information for within-season production decisions as well as for longer-term water reliability.

Contributions of GRACE to Understanding of Spatial Distribution of Spring Flooding in Snow-dominated Afghan Watersheds

Science.gov (United States)

Roningen, J. M.; Daly, S. F.; Vuyovich, C.

2012-12-01

In Afghanistan, where both historical and current in situ hydrologic records are extremely limited, the development and stability operations communities require guidance as to how to best utilize capabilities in remote sensing of the water cycle to understand and predict seasonal flooding. In this study, three versions of Level 3 GRACE datasets (CSR, CSR 4.1 and GRGS) are compared to TRMM 3B42 products, SSM/I-derived snow water equivalent products (SWE), and MODIS-derived flooding extents to assess their potential for contributing to an understanding of the spatial and temporal patterns of spring flooding in Afghanistan from the period 2002-2012. GRACE, which allows for assessment of correlations between small-scale temporal changes in the gravitational field of the earth with changes in the total water storage in the hydrosphere, opens the possibility for incorporation of subsurface components of the hydrologic cycle into remote monitoring and modeling of water resources. GRACE data exhibit clear seasonal fluctuations in many areas of Afghanistan, but an assessment is required of the extent to which this data can be disaggregated spatially and related to geographic patterns of precipitation, snowmelt and flooding. In this study, TRMM 3B42 and SSM/I-derived SWE datasets were used as proxies for measured precipitation. These datasets were convolved with a Gaussian filter with a 300 km half-radius at each reported GRACE data point in order to compensate for spatial correlation ('leakage' effects) in the GRACE data. In mountainous and snowmelt-dominated basins such as the majority of those in this study, GRACE analyses that make use of land surface model (LSM) derived estimates may not provide adequate characterization of snow water equivalent and soil moisture in this region. Therefore, soil and subsurface moisture were evaluated as a single storage component using the GRACE data, and flooding occurrence was evaluated as a qualitative surface expression of this

Results and Error Estimates from GRACE Forward Modeling over Antarctica

Science.gov (United States)

Bonin, Jennifer; Chambers, Don

2013-04-01

Forward modeling using a weighted least squares technique allows GRACE information to be projected onto a pre-determined collection of local basins. This decreases the impact of spatial leakage, allowing estimates of mass change to be better localized. The technique is especially valuable where models of current-day mass change are poor, such as over Antarctica. However when tested previously, the least squares technique has required constraints in the form of added process noise in order to be reliable. Poor choice of local basin layout has also adversely affected results, as has the choice of spatial smoothing used with GRACE. To develop design parameters which will result in correct high-resolution mass detection and to estimate the systematic errors of the method over Antarctica, we use a "truth" simulation of the Antarctic signal. We apply the optimal parameters found from the simulation to RL05 GRACE data across Antarctica and the surrounding ocean. We particularly focus on separating the Antarctic peninsula's mass signal from that of the rest of western Antarctica. Additionally, we characterize how well the technique works for removing land leakage signal from the nearby ocean, particularly that near the Drake Passage.

Sensitivity of the Gravity Recovery and Climate Experiment (GRACE) to the complexity of aquifer systems for monitoring of groundwater

Science.gov (United States)

Katpatal, Yashwant B.; Rishma, C.; Singh, Chandan K.

2018-05-01

The Gravity Recovery and Climate Experiment (GRACE) satellite mission is aimed at assessment of groundwater storage under different terrestrial conditions. The main objective of the presented study is to highlight the significance of aquifer complexity to improve the performance of GRACE in monitoring groundwater. Vidarbha region of Maharashtra, central India, was selected as the study area for analysis, since the region comprises a simple aquifer system in the western region and a complex aquifer system in the eastern region. Groundwater-level-trend analyses of the different aquifer systems and spatial and temporal variation of the terrestrial water storage anomaly were studied to understand the groundwater scenario. GRACE and its field application involve selecting four pixels from the GRACE output with different aquifer systems, where each GRACE pixel encompasses 50-90 monitoring wells. Groundwater storage anomalies (GWSA) are derived for each pixel for the period 2002 to 2015 using the Release 05 (RL05) monthly GRACE gravity models and the Global Land Data Assimilation System (GLDAS) land-surface models (GWSAGRACE) as well as the actual field data (GWSAActual). Correlation analysis between GWSAGRACE and GWSAActual was performed using linear regression. The Pearson and Spearman methods show that the performance of GRACE is good in the region with simple aquifers; however, performance is poorer in the region with multiple aquifer systems. The study highlights the importance of incorporating the sensitivity of GRACE in estimation of groundwater storage in complex aquifer systems in future studies.

Prognostic Accuracy of the GRACE Score in Octogenarians and Nonagenarians with Acute Coronary Syndromes

Directory of Open Access Journals (Sweden)

Antonio Mauricio dos Santos Cerqueira Junior

2018-02-01

Full Text Available Abstract Background: The GRACE Score was derived and validated from a cohort in which octogenarians and nonagenarians were poorly represented. Objective: To test the accuracy of the GRACE score in predicting in-hospital mortality of very elderly individuals with acute coronary syndromes (ACS. Methods: Prospective observational study conducted in the intensive coronary care unit of a tertiary center from September 2011 to August 2016. Patients consecutively admitted due to ACS were selected, and the very elderly group was defined by age ≥ 80 years. The GRACE Score was based on admission data and its accuracy was tested regarding prediction of in-hospital death. Statistical significance was defined by p value < 0,05. Results: A total of 994 individuals was studied, 57% male, 77% with non-ST elevation myocardial infarction and 173 (17% very elderly patients. The mean age of the sample was 65 ± 13 years, and the mean age of very elderly patients subgroup was 85 ± 3.7 years. The C-statistics of the GRACE Score in very elderly patients was 0.86 (95% CI = 0.78 - 0.93, with no difference when compared to the value for younger individuals 0.83 (95% CI = 0.75 - 0.91, with p = 0.69. The calibration of the score in very elderly patients was described by χ2 test of Hosmer-Lemeshow = 2.2 (p = 0.98, while the remaining patients presented χ2 = 9.0 (p = 0.35. Logistic regression analysis for death prediction did not show interaction between GRACE Score and variable of very elderly patients (p = 0.25. Conclusion: The GRACE Score in very elderly patients is accurate in predicting in-hospital ACS mortality, similarly to younger patients.

Comparison of Decadal Water Storage Trends from Global Hydrological Models and GRACE Satellite Data

Science.gov (United States)

Scanlon, B. R.; Zhang, Z. Z.; Save, H.; Sun, A. Y.; Mueller Schmied, H.; Van Beek, L. P.; Wiese, D. N.; Wada, Y.; Long, D.; Reedy, R. C.; Doll, P. M.; Longuevergne, L.

2017-12-01

Global hydrology is increasingly being evaluated using models; however, the reliability of these global models is not well known. In this study we compared decadal trends (2002-2014) in land water storage from 7 global models (WGHM, PCR-GLOBWB, and GLDAS: NOAH, MOSAIC, VIC, CLM, and CLSM) to storage trends from new GRACE satellite mascon solutions (CSR-M and JPL-M). The analysis was conducted over 186 river basins, representing about 60% of the global land area. Modeled total water storage trends agree with those from GRACE-derived trends that are within ±0.5 km3/yr but greatly underestimate large declining and rising trends outside this range. Large declining trends are found mostly in intensively irrigated basins and in some basins in northern latitudes. Rising trends are found in basins with little or no irrigation and are generally related to increasing trends in precipitation. The largest decline is found in the Ganges (-12 km3/yr) and the largest rise in the Amazon (43 km3/yr). Differences between models and GRACE are greatest in large basins (>0.5x106 km2) mostly in humid regions. There is very little agreement in storage trends between models and GRACE and among the models with values of r2 mostly store water over decadal timescales that is underrepresented by the models. The storage capacity in the modeled soil and groundwater compartments may be insufficient to accommodate the range in water storage variations shown by GRACE data. The inability of the models to capture the large storage trends indicates that model projections of climate and human-induced changes in water storage may be mostly underestimated. Future GRACE and model studies should try to reduce the various sources of uncertainty in water storage trends and should consider expanding the modeled storage capacity of the soil profiles and their interaction with groundwater.

Canova's 'The Three Graces'

Directory of Open Access Journals (Sweden)

Marković Kamenko M.

2009-01-01

Full Text Available Antonio Canova (1757-1822, the epitome of the neo-classical style, was born in a small village Passagno in the province of Treviso. At the age of fourteen he started learning sculpture in Venice; at first, he was placed under Giovanni Bernardi and, later on, under Giovanni Ferrari. After he had established himself as a sculptor, he moved to Rome, the city of classisists in which he would later achieve a worldwide fame. The highest level of his art were the statues of naked women which exposed a new type of female beauty as well as a new poetic style based on the beauty conceived in ancient Greece. This work gives a story of one of Canova's unknown pieces. It is about a group of marble statues 'The Three Graces' which can be found in the Regional Museum of Art in Craiova. Not even a word has it been written referring to this particular sculpture in Romania. These are the first words about this piece of art, placed somewhere out of sight at a dark corner of the museum only because they do not possess any valid documentation concerning its purchase. Only the signature was left on it by the author; however, it is certain that it came to life a few years after he moved to London. The sculpture might have been made (around 1820 four or five years prior to his first marble group of statues 'The Three Graces' standing in the Hermitage Museum in St Petersburg.

Determination of groundwater abstractions by means of GRACE data and Artificial Neural Networks

Science.gov (United States)

Gemitzi, Alexandra; Tsagkarakis, Konstantinos; Lakshmi, Venkat

2017-04-01

The EU Water Framework Directive requires for each groundwater body the determination of annual average rates of abstraction from all points providing more than 10m3 per day as well as groundwater level monitoring, so as to ensure that the available groundwater resource is not exceeded by the long-term annual average rate of abstraction. In order to acquire such information in situ observation networks are necessary. However, there are cases, e.g. Greece where WFD monitoring programme has not yet become operational due to bureaucratic, socioeconomic and often political constraints. The present study aims at determining groundwater use at the aquifer scale by using Gravity Recovery and Climate Experiment (GRACE) satellite data coupled with readily available meteorological data. Traditionally, GRACE data have been used at the global and regional scale due to their coarse resolution and the difficulties in disaggregating the various Total Water Storage (TWS) components. Previous works have evaluated the subsurface anomalies (ΔGW), using supplementary data sets and hydrologic modeling results in order to disaggregate GRACE TWS anomalies into their various components. Recent works however, have shown that changes in groundwater storage are dominating the GRACE Total Water Storage (TWS) changes, therefore it was though reasonable to use changes in Grace derived TWS in order to quantify abstractions from a groundwater body. Statistical downscaling was performed using an Artificial Neural Network in the form a Multilayer Perceptron model, in conjunction with local meteorological data. An ensemble of 100 ANNs provided a means of quantifying uncertainty and improving generalization. The methodology was applied in Rhodope area (NE Greece) and proved to be an efficient way of downscaling GRACE data in order to estimate the monthly quantity of water extracted from a certain aquifer. Although our methodology does not aim at estimating abstractions at single points, it manages

Characterization of spatio-temporal patterns for various GRACE- and GLDAS-born estimates for changes of global terrestrial water storage

Science.gov (United States)

Yang, Tao; Wang, Chao; Yu, Zhongbo; Xu, Feng

2013-10-01

Since the launch in March 2002, the Gravity Recovery and Climate Experiment (GRACE) satellite mission has provided us with a new method to estimate terrestrial water storage (TWS) variations by measuring earth gravity change with unprecedented accuracy. Thus far, a number of standardized GRACE-born TWS products are published by different international research teams. However, no characterization of spatio-temporal patterns for different GRACE hydrology products from the global perspective could be found. It is still a big challenge for the science community to identify the reliable global measurement of TWS anomalies due to our limited knowledge on the true value. Hence, it is urgently necessary to evaluate the uncertainty for various global estimates of the GRACE-born TWS changes by a number of international research organizations. Toward this end, this article presents an in-depth analysis for various GRACE-born and GLDAS-based estimates for changes of global terrestrial water storage. The work characterizes the inter-annual and intra-annual variability, probability density variations, and spatial patterns among different GRACE-born TWS estimates over six major continents, and compares them with results from GLDAS simulations. The underlying causes of inconsistency between GRACE- and GLDAS-born TWS estimates are thoroughly analyzed with an aim to improve our current knowledge in monitoring global TWS change. With a comprehensive consideration of the advantages and disadvantages among GRACE- and GLDAS-born TWS anomalies, a summary is thereafter recommended as a rapid reference for scientists, end-users, and policy-makers in the practices of global TWS change research. To our best knowledge, this work is the first attempt to characterize difference and uncertainty among various GRACE-born terrestrial water storage changes over the major continents estimated by a number of international research organizations. The results can provide beneficial reference to usage of

Ice loading model for Glacial Isostatic Adjustment in the Barents Sea constrained by GRACE gravity observations

Science.gov (United States)

Root, Bart; Tarasov, Lev; van der Wal, Wouter

2014-05-01

The global ice budget is still under discussion because the observed 120-130 m eustatic sea level equivalent since the Last Glacial Maximum (LGM) can not be explained by the current knowledge of land-ice melt after the LGM. One possible location for the missing ice is the Barents Sea Region, which was completely covered with ice during the LGM. This is deduced from relative sea level observations on Svalbard, Novaya Zemlya and the North coast of Scandinavia. However, there are no observations in the middle of the Barents Sea that capture the post-glacial uplift. With increased precision and longer time series of monthly gravity observations of the GRACE satellite mission it is possible to constrain Glacial Isostatic Adjustment in the center of the Barents Sea. This study investigates the extra constraint provided by GRACE data for modeling the past ice geometry in the Barents Sea. We use CSR release 5 data from February 2003 to July 2013. The GRACE data is corrected for the past 10 years of secular decline of glacier ice on Svalbard, Novaya Zemlya and Frans Joseph Land. With numerical GIA models for a radially symmetric Earth, we model the expected gravity changes and compare these with the GRACE observations after smoothing with a 250 km Gaussian filter. The comparisons show that for the viscosity profile VM5a, ICE-5G has too strong a gravity signal compared to GRACE. The regional calibrated ice sheet model (GLAC) of Tarasov appears to fit the amplitude of the GRACE signal. However, the GRACE data are very sensitive to the ice-melt correction, especially for Novaya Zemlya. Furthermore, the ice mass should be more concentrated to the middle of the Barents Sea. Alternative viscosity models confirm these conclusions.

Comparison of GRACE with in situ hydrological measurement data ...

African Journals Online (AJOL)

Comparison of GRACE with in situ hydrological measurement data shows storage depletion in Hai River basin, Northern China. ... of the world, their application in conjunction with hydrological models could improve hydrological studies.

Checkpointing for graceful degradation in distributed embedded systems

Science.gov (United States)

Sababha, Belal Hussein

Graceful degradation is an approach to developing dependable safety-critical embedded applications, where redundant active or standby resources are used to cope with faults through a system reconfiguration at run-time. Compared to traditional hardware and software redundancy, it is a promising technique that may achieve dependability with a significant reduction in cost, size, weight, and power requirements. Reconfiguration at run-time necessitates using proper checkpointing protocols to support state reservation to ensure correct task restarts after a system reconfiguration. One of the most common checkpointing protocols are communication induced checkpointing (CIC) protocols, which are well developed and understood for large parallel and information systems, but not much has been done for resource limited embedded systems. This work implements and evaluates some of the most common CIC protocols in a periodic resource constrained distributed embedded system for graceful degradation purposes. A test-bed has been developed and used for the evaluation of the various protocols. The implemented protocols are thoroughly studied and performances are contrasted. Specifically the periodicity property and how it benefits checkpointing in embedded systems is investigated. This work introduces a unique effort of CIC protocol implementation and evaluation in the field of distributed embedded systems. Other than providing a test-bed for graceful degradation support, this work shows that some checkpointing protocols that are not efficient in large information systems and supercomputers perform well in embedded systems. We show that a simple index-based CIC protocol, such as the BCS protocol, is more appropriate in embedded system applications compared to other protocols that piggyback a significant amount of information to reduce the number of forced checkpoints. Finally, this work proposes a whole graceful degradation approach to achieve fault tolerance in resource constrained

Does C-reactive Protein Add Prognostic Value to GRACE Score in Acute Coronary Syndromes?

International Nuclear Information System (INIS)

Correia, Luis Cláudio Lemos; Vasconcelos, Isis; Garcia, Guilherme; Kalil, Felipe; Ferreira, Felipe; Silva, André; Oliveira, Ruan; Carvalhal, Manuela; Freitas, Caio; Noya-Rabelo, Márcia Maria

2014-01-01

The incremental prognostic value of plasma levels of C-reactive protein (CRP) in relation to GRACE score has not been established in patients with acute coronary syndrome (ACS) with non-ST segment elevation. To test the hypothesis that CRP measurements at admission increases the prognostic value of GRACE score in patients with ACS. A total of 290 subjects, consecutively admitted for ACS, with plasma material obtained upon admission CRP measurement using a high-sensitivity method (nephelometry) were studied. Cardiovascular outcomes during hospitalization were defined by the combination of death, nonfatal myocardial infarction or nonfatal refractory angina. The incidence of cardiovascular events during hospitalization was 15% (18 deaths, 11 myocardial infarctions, 13 angina episodes) with CRP showing C-statistics of 0.60 (95% CI = 0.51-0.70, p = 0.034) in predicting these outcomes. After adjustment for the GRACE score, elevated CRP (defined as the best cutoff point) tended to be associated with hospital events (OR = 1.89, 95% CI = 0.92 to 3.88, p = 0.08). However, the addition of the variable elevated CRP in the GRACE model did not result in significant increase in C-statistics, which ranged from 0.705 to 0.718 (p = 0.46). Similarly, there was no significant reclassification of risk with the addition of CRP in the predictor model (net reclassification = 5.7 %, p = 0.15). Although CRP is associated with hospital outcomes, this inflammatory marker does not increase the prognostic value of the GRACE score

Does C-reactive Protein Add Prognostic Value to GRACE Score in Acute Coronary Syndromes?

Energy Technology Data Exchange (ETDEWEB)

Correia, Luis Cláudio Lemos, E-mail: lccorreia@terra.com.br; Vasconcelos, Isis; Garcia, Guilherme; Kalil, Felipe; Ferreira, Felipe; Silva, André; Oliveira, Ruan; Carvalhal, Manuela; Freitas, Caio; Noya-Rabelo, Márcia Maria [Escola Bahiana de Medicina e Saúde Pública, Salvador, BA (Brazil); Hospital São Rafael, Salvador, BA (Brazil)

2014-05-15

The incremental prognostic value of plasma levels of C-reactive protein (CRP) in relation to GRACE score has not been established in patients with acute coronary syndrome (ACS) with non-ST segment elevation. To test the hypothesis that CRP measurements at admission increases the prognostic value of GRACE score in patients with ACS. A total of 290 subjects, consecutively admitted for ACS, with plasma material obtained upon admission CRP measurement using a high-sensitivity method (nephelometry) were studied. Cardiovascular outcomes during hospitalization were defined by the combination of death, nonfatal myocardial infarction or nonfatal refractory angina. The incidence of cardiovascular events during hospitalization was 15% (18 deaths, 11 myocardial infarctions, 13 angina episodes) with CRP showing C-statistics of 0.60 (95% CI = 0.51-0.70, p = 0.034) in predicting these outcomes. After adjustment for the GRACE score, elevated CRP (defined as the best cutoff point) tended to be associated with hospital events (OR = 1.89, 95% CI = 0.92 to 3.88, p = 0.08). However, the addition of the variable elevated CRP in the GRACE model did not result in significant increase in C-statistics, which ranged from 0.705 to 0.718 (p = 0.46). Similarly, there was no significant reclassification of risk with the addition of CRP in the predictor model (net reclassification = 5.7 %, p = 0.15). Although CRP is associated with hospital outcomes, this inflammatory marker does not increase the prognostic value of the GRACE score.

Can we observe the fronts of the Antarctic Circumpolar Current using GRACE OBP?

Science.gov (United States)

Makowski, J.; Chambers, D. P.; Bonin, J. A.

2014-12-01

The Antarctic Circumpolar Current (ACC) and the Southern Ocean remains one of the most undersampled regions of the world's oceans. The ACC is comprised of four major fronts: the Sub-Tropical Front (STF), the Polar Front (PF), the Sub-Antarctic Front (SAF), and the Southern ACC Front (SACCF). These were initially observed individually from repeat hydrographic sections and their approximate locations globally have been quantified using all available temperature data from the World Ocean and Climate Experiment (WOCE). More recent studies based on satellite altimetry have found that the front positions are more dynamic and have shifted south by up to 1° on average since 1993. Using ocean bottom pressure (OBP) data from the current Gravity Recovery and Climate Experiment (GRACE) we have measured integrated transport variability of the ACC south of Australia. However, differentiation of variability of specific fronts has been impossible due to the necessary smoothing required to reduce noise and correlated errors in the measurements. The future GRACE Follow-on (GFO) mission and the post 2020 GRACE-II mission are expected to produce higher resolution gravity fields with a monthly temporal resolution. Here, we study the resolution and error characteristics of GRACE gravity data that would be required to resolve variations in the front locations and transport. To do this, we utilize output from a high-resolution model of the Southern Ocean, hydrology models, and ice sheet surface mass balance models; add various amounts of random and correlated errors that may be expected from GFO and GRACE-II; and quantify requirements needed for future satellite gravity missions to resolve variations along the ACC fronts.

Combining GRACE and Altimetry to solve for present day mass changes and GIA

Science.gov (United States)

Rietbroek, R.; Lück, C.; Uebbing, B.; Kusche, J.; King, M. A.

2017-12-01

Past and present day sea level rise is closely linked to geoid and surface deformation changes from the ongoing glacial isostatic adjustment (GIA). Sea level, as detected by radar altimetry, senses the radial deformation of the ocean floor as mantle material slowly flows back to the locations of the former glacial domes. This manifests itself as a net subsidence when averaged over the entire ocean, but can regionally be seen as an uplift for locations close to the former ice sheets. Furthermore, mass driven sea level as derived from GRACE, is even more sensitive to GIA induced mass redistribution in the solid Earth. Consequently, errors in GIA corrections, most notably errors in mantle viscosity and ice histories, have a different leverage on regional sea level estimates from GRACE and altimetry. In this study, we discuss the abilities of a GRACE-altimetry combination to co-estimate GIA corrections together with present day contributors to sea level, rather than simply prescribing a GIA correction from a model. The data is combined in a joint inversion scheme which makes use of spatial patterns to parameterize present day loading effects and GIA. We show that the GRACE-altimetry combination requires constraints, but generally steers the Antarctic GIA signal towards a weaker present day signal in Antarctica compared to a ICE5-G(VM2) derived model. Furthermore, in light of the aging GRACE mission, we show sensitivity studies of how well one could estimate GIA corrections when using other low earth orbiters such as SWARM or CHAMP. Finally, we show whether the Antarctic GNSS station network may be useful in separating GIA from present day mass signals in this type of inversion schemes.

Phase Error Modeling and Its Impact on Precise Orbit Determination of GRACE Satellites

Directory of Open Access Journals (Sweden)

Jia Tu

2012-01-01

Full Text Available Limiting factors for the precise orbit determination (POD of low-earth orbit (LEO satellite using dual-frequency GPS are nowadays mainly encountered with the in-flight phase error modeling. The phase error is modeled as a systematic and a random component each depending on the direction of GPS signal reception. The systematic part and standard deviation of random part in phase error model are, respectively, estimated by bin-wise mean and standard deviation values of phase postfit residuals computed by orbit determination. By removing the systematic component and adjusting the weight of phase observation data according to standard deviation of random component, the orbit can be further improved by POD approach. The GRACE data of 1–31 January 2006 are processed, and three types of orbit solutions, POD without phase error model correction, POD with mean value correction of phase error model, and POD with phase error model correction, are obtained. The three-dimensional (3D orbit improvements derived from phase error model correction are 0.0153 m for GRACE A and 0.0131 m for GRACE B, and the 3D influences arisen from random part of phase error model are 0.0068 m and 0.0075 m for GRACE A and GRACE B, respectively. Thus the random part of phase error model cannot be neglected for POD. It is also demonstrated by phase postfit residual analysis, orbit comparison with JPL precise science orbit, and orbit validation with KBR data that the results derived from POD with phase error model correction are better than another two types of orbit solutions generated in this paper.

Analysis of Seasonal Variability in Gulf of Alaska Glacier Mass Balance using GRACE

Science.gov (United States)

Arendt, A. A.; Luthcke, S. B.; Oneel, S.; Gardner, A. S.; Hill, D. F.

2011-12-01

Mass variations of glaciers in Alaska/northwestern Canada must be quantified in order to assess impacts on ecosystems, human infrastructure, and global sea level. Here we combine Gravity Recovery and Climate Experiment (GRACE) observations with a wide range of satellite and field data to investigate drivers of these recent changes, with a focus on seasonal variations. Our central focus will be the exceptionally high mass losses of 2009, which do not correlate with weather station temperature and precipitation data, but may be linked to ash fall from the March 31, 2009 eruption of Mt. Redoubt. The eruption resulted in a significant decrease in MODIS-derived surface albedo over many Alaska glacier regions, and likely contributed to some of the 2009 anomalous mass loss observed by GRACE. We also focus on the Juneau and Stikine Icefield regions that are far from the volcanic eruption but experienced the largest mass losses of any region in 2009. Although rapid drawdown of tidewater glaciers was occurring in southeast Alaska during 2009, we show these changes were probably not sufficiently widespread to explain all of the GRACE signal in those regions. We examine additional field and satellite datasets to quantify potential errors in the climate and GRACE fields that could result in the observed discrepancy.

Assessment of 3D hydrologic deformation using GRACE and GPS

Science.gov (United States)

Watson, C. S.; Tregoning, P.; Fleming, K.; Burgette, R. J.; Featherstone, W. E.; Awange, J.; Kuhn, M.; Ramillien, G.

2009-12-01

Hydrological processes cause variations in gravitational potential and surface deformations, both of which are detectable with ever increasing precision using space geodetic techniques. By comparing the elastic deformation computed from continental water load estimates derived from the Gravity Recovery and Climate Experiment (GRACE), with three-dimensional surface deformation derived from GPS observations, there is clear potential to better understand global to regional hydrological processes, in addition to acquiring further insight into the systematic error contributions affecting each space geodetic technique. In this study, we compare elastic deformation derived from water load estimates taken from the CNES, CSR, GFZ and JPL time variable GRACE fields. We compare these surface displacements with those derived at a global network of GPS sites that have been homogeneously reprocessed in the GAMIT/GLOBK suite. We extend our comparison to include a series of different GPS solutions, with each solution only subtly different based on the methodology used to down weight the height component in realizing site coordinates on the terrestrial reference frame. Each of the GPS solutions incorporate modeling of atmospheric loading and utilization of the VMF1 and a priori zenith hydrostatic delays derived via ray tracing through ECMWF meteorological fields. The agreement between GRACE and GPS derived deformations is not limited to the vertical component, with excellent agreement in the horizontal component across areas where large hydrologic signals occur over broad spatial scales (with correlation in horizontal components as high as 0.9). Agreement is also observed at smaller scales, including across Europe. These comparisons assist in understanding the magnitude of current error contributions within both space geodetic techniques. With the emergence of homogeneously reprocessed GPS time series spanning the GRACE mission, this technique offers one possible means of

Grace Omollo Misere and Anne Akoth Misere | IDRC - International ...

International Development Research Centre (IDRC) Digital Library (Canada)

Combinatorics has led Grace to work on a conjecture proposed by John Conway, ... and governments in Kenya and the region improve their performance through the ... African women mathematical scientists working on climate change issues.

Antarctic Ocean Tides from GRACE Intersatellite Tracking Data and Hydrodynamic Assimilation

Science.gov (United States)

Erofeeva, S.; Han, S.; Ray, R.; Egbert, G.; Luthcke, S.

2007-12-01

Long-wavelength components of the oceanic tides surrounding Antarctica are estimated from over three years of GRACE satellite-to-satellite ranging measurements. An inversion is performed for the major constituents M2, O1, and S2, parameterized as localized average mass anomalies relative to a prior tidal model. Satellite state adjustments are made simultaneously. These long-wavelength anomalies are then assimilated into a high-resolution regional hydrodynamic tidal model. Comparisons to independent "ground truth" data, previously collected by King and Padman, show that assimilation of the GRACE inversions results in improved accuracy, for all three constituents.

Characterizing hydrological activities over Yangtze River basin using the new HUST-Grace2016 model, MODIS, and NCEP/NCAR data

Science.gov (United States)

Zhou, H.; Luo, Z.; Tangdamrongsub, N.; He, L.

2017-12-01

Accurate TWS estimation is important to evaluate the situation of the water resource over the Yangtze River basin. This study exploits the TWS observation from the new gravity model, HUST-Grace06, which is developed by a new low-frequency noise processing strategy. A novel GRACE post-processing approach is proposed to enhance the quality of the TWS estimate, and the improved TWS is used to characterize the hydrological activities over the Yangtze River basin. The approach includes the effective noise reduction and the leakage error mitigation based on forward modeling. The HUST-Grace06 derived TWS presents good agreement with the CSR mascon solution as well as the PCR-GLOBWB hydrological model. Particularly, our solution provides remarkable performance in identifying the extreme climate events e.g., flood and drought over the Yangtze River basin. In addition, for the first time, the NCEP/NCAR reanalysis data is incorporated with GRACE in the exploration of the climate induced hydrological activities. The comparison between GRACE and the MODIS-derived NDVI data is also conducted to investigate their connection regarding temporal and spatial distribution. The analysis suggests that the terrestrial reflectance data can be used to represent the TWS information. Importantly, such information can be used to fill the missing data in case of the early termination of GRACE or during the prelaunch of the GRACE Follow-On mission.

RFP to work on formation flying capabilities for spacecrafts for the GRACE project

DEFF Research Database (Denmark)

Riis, Troels; Thuesen, Gøsta; Kilsgaard, Søren

1999-01-01

The National Aeronautics and Space Agency of USA, NASA, are working on formation flying capabilities for spacecrafts, GRACE Project. IAU and JPL are developing the inter spacecraft attitude link to be used on the two spacecrafts.......The National Aeronautics and Space Agency of USA, NASA, are working on formation flying capabilities for spacecrafts, GRACE Project. IAU and JPL are developing the inter spacecraft attitude link to be used on the two spacecrafts....

The GRACE system for the minimal supersymmetric standard model

International Nuclear Information System (INIS)

Tanaka, H.; Kaneko, T.; Jimbo, M.; Kon, T.

1997-01-01

The algorithm of constructing the Feynman amplitudes for the GRACE system is extended to processes involving supersymmetric particles. New vertex amplitude subroutines needed to compute these processes are now part of the CHANEL library. (orig.)

Integrating Enhanced Grace Terrestrial Water Storage Data Into the U.S. and North American Drought Monitors

Science.gov (United States)

Housborg, Rasmus; Rodell, Matthew

2010-01-01

NASA's Gravity Recovery and Climate Experiment (GRACE) satellites measure time variations nf the Earth's gravity field enabling reliable detection of spatio-temporal variations in total terrestrial water storage (TWS), including ground water. The U.S. and North American Drought Monitors are two of the premier drought monitoring products available to decision-makers for assessing and minimizing drought impacts, but they rely heavily on precipitation indices and do not currently incorporate systematic observations of deep soil moisture and groundwater storage conditions. Thus GRACE has great potential to improve the Drought Monitors hy filling this observational gap. Horizontal, vertical and temporal disaggregation of the coarse-resolution GRACE TWS data has been accomplished by assimilating GRACE TWS anomalies into the Catchment Land Surface Model using ensemble Kalman smoother. The Drought Monitors combine several short-term and long-term drought indices and indicators expressed in percentiles as a reference to their historical frequency of occurrence for the location and time of year in question. To be consistent, we are in the process of generating a climatology of estimated soil moisture and ground water based on m 60-year Catchment model simulation which will subsequently be used to convert seven years of GRACE assimilated fields into soil moisture and groundwater percentiles. for systematic incorporation into the objective blends that constitute Drought Monitor baselines. At this stage we provide a preliminary evaluation of GRACE assimilated Catchment model output against independent datasets including soil moisture observations from Aqua AMSR-E and groundwater level observations from the U.S. Geological Survey's Groundwater Climate Response Network.

Comparison of GPS and GRACE hydrological loading signatures in Myanmar, India, Bangladesh, and Bhutan

Science.gov (United States)

Materna, K.; Feng, L.; Lindsey, E. O.; Hill, E.; Burgmann, R.

2017-12-01

The elastic response of the lithosphere to surface mass redistributions produces significant deformation that can be observed in geodetic time series. This deformation is especially pronounced in Southeast Asia, where the annual monsoon produces large-amplitude hydrological loads. The MIBB network of 20 continuous GPS stations in Myanmar, India, Bangladesh, and Bhutan, operational since 2012, provides an opportunity to study the earth's response to these loads. In this study, we use GRACE gravity products as an estimate of surface water distribution, and input these estimates into an elastic loading calculation. We compare the predicted deformation with that observed with GPS. We find that elastic loading from the GRACE gravity field is able to explain the phase and the peak-to-peak amplitude (typically 2-3 cm) of the vertical GPS oscillations in northeast India and central Myanmar. GRACE-based corrections reduce the RMS scatter of the GPS data by 30%-45% in these regions. However, this approach does not capture all of the variation in central Bangladesh and southern Myanmar. Local hydrological effects, non-tidal ocean loads, poroelastic deformation, or differences in elastic properties may explain discrepancies between the GPS and GRACE signals in these places. The results of our calculations have practical implications for campaign GPS measurements in Myanmar, which make up the majority of geodetic measurements at this point. We may be able to reduce errors in campaign measurements and increase the accuracy of velocity estimates by correcting for hydrologic signals with GRACE data. The results also have potential implications for crustal rheology in Southeast Asia.

Application of EOF/PCA-based methods in the post-processing of GRACE derived water variations

Science.gov (United States)

Forootan, Ehsan; Kusche, Jürgen

2010-05-01

Two problems that users of monthly GRACE gravity field solutions face are 1) the presence of correlated noise in the Stokes coefficients that increases with harmonic degree and causes ‘striping', and 2) the fact that different physical signals are overlaid and difficult to separate from each other in the data. These problems are termed the signal-noise separation problem and the signal-signal separation problem. Methods that are based on principal component analysis and empirical orthogonal functions (PCA/EOF) have been frequently proposed to deal with these problems for GRACE. However, different strategies have been applied to different (spatial: global/regional, spectral: global/order-wise, geoid/equivalent water height) representations of the GRACE level 2 data products, leading to differing results and a general feeling that PCA/EOF-based methods are to be applied ‘with care'. In addition, it is known that conventional EOF/PCA methods force separated modes to be orthogonal, and that, on the other hand, to either EOFs or PCs an arbitrary orthogonal rotation can be applied. The aim of this paper is to provide a common theoretical framework and to study the application of PCA/EOF-based methods as a signal separation tool due to post-process GRACE data products. In order to investigate and illustrate the applicability of PCA/EOF-based methods, we have employed them on GRACE level 2 monthly solutions based on the Center for Space Research, University of Texas (CSR/UT) RL04 products and on the ITG-GRACE03 solutions from the University of Bonn, and on various representations of them. Our results show that EOF modes do reveal the dominating annual, semiannual and also long-periodic signals in the global water storage variations, but they also show how choosing different strategies changes the outcome and may lead to unexpected results.

REVIEW A SPACE FOR GRACE: TOWARDS AN AESTHETICS OF ...

African Journals Online (AJOL)

REVIEW. A SPACE FOR. GRACE: TOWARDS. AN AESTHETICS OF. PREACHING ... Cilliers' views of space and time are clearly post-Einstein and post-. Hawking. .... in the step-by-step, week-in-week-out process of sermon preparation. The.

Human-induced Terrestrial Water Storage Change: A Global Analysis using Hydrological Models and GRACE

Science.gov (United States)

Felfelani, F.; Pokhrel, Y. N.

2016-12-01

Hydrological models and data derived from the Gravity Recovery and Climate Experiment (GRACE) satellite mission are used to study terrestrial water storage (TWS) change; however, both have disadvantages that necessitate the integrated use of them. While GRACE doesn't disintegrate the vertical storage into its components, most models do not account for human activities. Here we use two Land Surface Models (LSMs), i.e., HiGW-MAT and PCRGLOBWB that fully couple natural and human drivers of changes in water cycle, explicitly simulating the changes in various TWS compartments. We first evaluate the models performance with GRACE observations. Then, we quantify the human footprint over global river basins located in different geographic and climate regions. To quantify human impacts, a new framework is proposed based on the GRACE observations (representing both climate variability and human activities) together with the natural simulation of LSMs using water budget equation (P-ET-R; P for precipitation, ET for evapotranspiration, and R for runoff). Finally, we examine the uncertainty in TWS simulations arising from the uncertainties in forcing data. Results indicate that, in snow-dominated regions, PCRGLOBWB generally fails to reproduce neither the interannual variability of observed TWS nor the seasonal cycle, while HiGW-MAT model shows significantly better results. In basins with human signatures, PCRGLOBWB generally shows better agreement with GRACE compared to HiGW-MAT. It is found that HiGW-MAT tends to overestimate groundwater depletion in basins with human impacts (e.g., Amudarya, Colorado, Euphrates and Indus), which results in larger negative interannual TWS trend compared to GRACE. Euphrates and Ganges river basins experience the highest human-induced TWS deficit rates (2.08 cm/yr and 1.94 cm/yr, respectively) during the simulation period of 2002-2010. Uncertainty analysis of results from the same model but with different forcing data suggests a high standard

GRACE L1b inversion through a self-consistent modified radial basis function approach

Science.gov (United States)

Yang, Fan; Kusche, Juergen; Rietbroek, Roelof; Eicker, Annette

2016-04-01

Implementing a regional geopotential representation such as mascons or, more general, RBFs (radial basis functions) has been widely accepted as an efficient and flexible approach to recover the gravity field from GRACE (Gravity Recovery and Climate Experiment), especially at higher latitude region like Greenland. This is since RBFs allow for regionally specific regularizations over areas which have sufficient and dense GRACE observations. Although existing RBF solutions show a better resolution than classical spherical harmonic solutions, the applied regularizations cause spatial leakage which should be carefully dealt with. It has been shown that leakage is a main error source which leads to an evident underestimation of yearly trend of ice-melting over Greenland. Unlike some popular post-processing techniques to mitigate leakage signals, this study, for the first time, attempts to reduce the leakage directly in the GRACE L1b inversion by constructing an innovative modified (MRBF) basis in place of the standard RBFs to retrieve a more realistic temporal gravity signal along the coastline. Our point of departure is that the surface mass loading associated with standard RBF is smooth but disregards physical consistency between continental mass and passive ocean response. In this contribution, based on earlier work by Clarke et al.(2007), a physically self-consistent MRBF representation is constructed from standard RBFs, with the help of the sea level equation: for a given standard RBF basis, the corresponding MRBF basis is first obtained by keeping the surface load over the continent unchanged, but imposing global mass conservation and equilibrium response of the oceans. Then, the updated set of MRBFs as well as standard RBFs are individually employed as the basis function to determine the temporal gravity field from GRACE L1b data. In this way, in the MRBF GRACE solution, the passive (e.g. ice melting and land hydrology response) sea level is automatically

A Record-High Ocean Bottom Pressure in the South Pacific Observed by GRACE

Science.gov (United States)

Boening, Carmen; Lee, Tong; Zlotnicki, Victor

2011-01-01

In late 2009 to early 2010, the Gravity Recovery and Climate Experiment (GRACE) satellite pair observed a record increase in ocean bottom pressure (OBP) over a large mid-latitude region of the South East Pacific. Its magnitude is substantially larger than other oceanic events in the Southern Hemisphere found in the entire GRACE data records (2003-2010) on multi-month time scales. The OBP data help to understand the nature of a similar signal in sea surface height (SSH) anomaly observed by altimetry: the SSH increase is mainly due to mass convergence. Analysis of the barotropic vorticity equation using scatterometer data, atmospheric reanalysis product, and GRACE and altimeter an atmospheric reanalysis product observations suggests that the observed OBP/SSH signal was primarily caused by wind stress curl associated with a strong and persistent anticyclone in late 2009 in combination with effects of planetary vorticity gradient, bottom topography, and friction

California Drought Recovery Assessment Using GRACE Satellite Gravimetry Information

Science.gov (United States)

Love, C. A.; Aghakouchak, A.; Madadgar, S.; Tourian, M. J.

2015-12-01

California has been experiencing its most extreme drought in recent history due to a combination of record high temperatures and exceptionally low precipitation. An estimate for when the drought can be expected to end is needed for risk mitigation and water management. A crucial component of drought recovery assessments is the estimation of terrestrial water storage (TWS) deficit. Previous studies on drought recovery have been limited to surface water hydrology (precipitation and/or runoff) for estimating changes in TWS, neglecting the contribution of groundwater deficits to the recovery time of the system. Groundwater requires more time to recover than surface water storage; therefore, the inclusion of groundwater storage in drought recovery assessments is essential for understanding the long-term vulnerability of a region. Here we assess the probability, for varying timescales, of California's current TWS deficit returning to its long-term historical mean. Our method consists of deriving the region's fluctuations in TWS from changes in the gravity field observed by NASA's Gravity Recovery and Climate Experiment (GRACE) satellites. We estimate the probability that meteorological inputs, precipitation minus evaporation and runoff, over different timespans will balance the current GRACE-derived TWS deficit (e.g. in 3, 6, 12 months). This method improves upon previous techniques as the GRACE-derived water deficit comprises all hydrologic sources, including surface water, groundwater, and snow cover. With this empirical probability assessment we expect to improve current estimates of California's drought recovery time, thereby improving risk mitigation.

Grace and Courtesy: A Human Responsibility. AMI/USA Conference (Oak Brook, Illinois, July 23-26, 1998).

Science.gov (United States)

American Montessori International of the United States, Inc., Rochester, NY.

This conference proceedings compile presentations from a 1998 meeting of the American Montessori International of the United States, focusing on the importance of grace and courtesy in children's lives and in Montessori education. The papers presented are: (1) "Grace--The Felicity of Being" (Renilde Montessori); (2) "A Montessori…

Assimilating GRACE terrestrial water storage data into a conceptual hydrology model for the River Rhine

Science.gov (United States)

Widiastuti, E.; Steele-Dunne, S. C.; Gunter, B.; Weerts, A.; van de Giesen, N.

2009-12-01

Terrestrial water storage (TWS) is a key component of the terrestrial and global hydrological cycles, and plays a major role in the Earth’s climate. The Gravity Recovery and Climate Experiment (GRACE) twin satellite mission provided the first space-based dataset of TWS variations, albeit with coarse resolution and limited accuracy. Here, we examine the value of assimilating GRACE observations into a well-calibrated conceptual hydrology model of the Rhine river basin. In this study, the ensemble Kalman filter (EnKF) and smoother (EnKS) were applied to assimilate the GRACE TWS variation data into the HBV-96 rainfall run-off model, from February 2003 to December 2006. Two GRACE datasets were used, the DMT-1 models produced at TU Delft, and the CSR-RL04 models produced by UT-Austin . Each center uses its own data processing and filtering methods, yielding two different estimates of TWS variations and therefore two sets of assimilated TWS estimates. To validate the results, the model estimated discharge after the data assimilation was compared with measured discharge at several stations. As expected, the updated TWS was generally somewhere between the modeled and observed TWS in both experiments and the variance was also lower than both the prior error covariance and the assumed GRACE observation error. However, the impact on the discharge was found to depend heavily on the assimilation strategy used, in particular on how the TWS increments were applied to the individual storage terms of the hydrology model.

On the capability of Swarm for surface mass variation monitoring: Quantitative assessment based on orbit information from CHAMP, GRACE and GOCE

Science.gov (United States)

Baur, Oliver; Weigelt, Matthias; Zehentner, Norbert; Mayer-Gürr, Torsten; Jäggi, Adrian

2014-05-01

In the last decade, temporal variations of the gravity field from GRACE observations have become one of the most ubiquitous and valuable sources of information for geophysical and environmental studies. In the context of global climate change, mass balance of the Arctic and Antarctic ice sheets gained particular attention. Because GRACE has outlived its predicted lifetime by several years already, it is very likely that a gap between GRACE and its successor GRACE follow-on (supposed to be launched in 2017, at the earliest) occurs. The Swarm mission - launched on November 22, 2013 - is the most promising candidate to bridge this potential gap, i.e., to directly acquire large-scale mass variation information on the Earth's surface in case of a gap between the present GRACE and the upcoming GRACE follow-on projects. Although the magnetometry mission Swarm has not been designed for gravity field purposes, its three satellites have the characteristics for such an endeavor: (i) low, near-circular and near-polar orbits, (ii) precise positioning with high-quality GNSS receivers, (iii) on-board accelerometers to measure the influence of non-gravitational forces. Hence, from an orbit analysis point of view the Swarm satellites are comparable to the CHAMP, GRACE and GOCE spacecraft. Indeed and as data analysis from CHAMP has been shown, the detection of annual signals and trends from orbit analysis is possible for long-wavelength features of the gravity field, although the accuracy associated with the inter-satellite GRACE measurements cannot be reached. We assess the capability of the (non-dedicated) mission Swarm for mass variation detection in a real-case environment (opposed to simulation studies). For this purpose, we "approximate" the Swarm scenario by the GRACE+CHAMP and GRACE+GOCE constellations. In a first step, kinematic orbits of the individual satellites are derived from GNSS observations. From these orbits, we compute monthly combined GRACE+CHAMP and GRACE

Groundwater depletion in Central Mexico: Use of GRACE and InSAR to support water resources management

Science.gov (United States)

Castellazzi, Pascal; Martel, Richard; Rivera, Alfonso; Huang, Jianliang; Pavlic, Goran; Calderhead, Angus I.; Chaussard, Estelle; Garfias, Jaime; Salas, Javier

2016-08-01

Groundwater deficits occur in several areas of Central Mexico, where water resource assessment is limited by the availability and reliability of field data. In this context, GRACE and InSAR are used to remotely assess groundwater storage loss in one of Mexico's most important watersheds in terms of size and economic activity: the Lerma-Santiago-Pacifico (LSP). In situ data and Land Surface Models are used to subtract soil moisture and surface water storage changes from the total water storage change measured by GRACE satellites. As a result, groundwater mass change time-series are obtained for a 12 years period. ALOS-PALSAR images acquired from 2007 to 2011 were processed using the SBAS-InSAR algorithm to reveal areas subject to ground motion related to groundwater over-exploitation. In the perspective of providing guidance for groundwater management, GRACE and InSAR observations are compared with official water budgets and field observations. InSAR-derived subsidence mapping generally agrees well with official water budgets, and shows that deficits occur mainly in cities and irrigated agricultural areas. GRACE does not entirely detect the significant groundwater losses largely reported by official water budgets, literature and InSAR observations. The difference is interpreted as returns of wastewater to the groundwater flow systems, which limits the watershed scale groundwater depletion but suggests major impacts on groundwater quality. This phenomenon is enhanced by ground fracturing as noticed in the field. Studying the fate of the extracted groundwater is essential when comparing GRACE data with higher resolution observations, and particularly in the perspective of further InSAR/GRACE combination in hydrogeology.

Surface mass redistribution inversion from global GPS deformation and Gravity Recovery and Climate Experiment (GRACE) gravity data

NARCIS (Netherlands)

Kusche, J.; Schrama, E.J.O.

2005-01-01

Monitoring hydrological redistributions through their integrated gravitational effect is the primary aim of the Gravity Recovery and Climate Experiment (GRACE) mission. Time?variable gravity data from GRACE can be uniquely inverted to hydrology, since mass transfers located at or near the Earth's

Glacial Isostatic Adjustment as a Source of Noise for the Interpretation of GRACE Data

Science.gov (United States)

Wahr, J.; Velicogna, I.; Paulson, A.

2009-05-01

Viscoelastic relaxation in the Earth's mantle caused by wide-spread deglaciation following the last glacial maximum (LGM), can appear as a secular trend in measurements of the Earth's time-variable gravity field. The presence of this trend can provide an opportunity to use gravity observations to constrain models of the glacial isostatic adjustment (GIA) process. But it can also be a nuisance for people who are using the gravity observations to learn about other things. Gravity observations, whether from satellites or from ground-based gravimeters, can not distinguish between the gravitational effects of water/snow/ice variations on or near the surface, and those caused by density variations deep within the mantle. Unmodeled or mismodeled GIA signals can sometimes make it difficult to use gravity observations to learn about secular changes in water/snow/ice from such places as northern Canada, Scandinavia, Antarctica, and Greenland: places where there was considerable long-term deglaciation following the LGM. These issues have become particularly important since the 2002 launch of the GRACE gravity satellite mission. GIA signals in northern Canada and Scandinavia are clearly evident in the GRACE data. But the presence of GIA signals in these and other regions has sometimes caused problems for long-term hydrological and, especially, cryospheric studies with GRACE. GIA model errors, for example, are by far the largest source of uncertainty when using GRACE to estimate present-day thinning rates of the Antarctic ice sheet. This talk will discuss the contributions of the GIA signal to GRACE time-variable gravity measurements; partly as an opportunity to study the GIA process, but mostly as a source of uncertainty for other applications.

Request for personal participation of the salvific grace in the celebration of the sacred sacraments

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Jan Szczych

2016-06-01

Full Text Available It is through the participation of the faithful in the sacramental liturgies of the Church that salvation is accomplished. The faithful, desirous of a supernatural relationship with God, through their own life experience endeavor to actively translate into practice the mystery of Christ’s salvific grace. For this reason, the words pronounced by the person when first requesting the grace of any sacrament, either for themselves or on someone else’s behalf, find their full justification when repeated during the actual ceremony. Intentional request for the concession of any sacrament, which enables a personal participation of Christ’s grace, is a result of Christian faith, and activates a conscious and fruitful participation in the redeeming sacrifice of Christ.

Spread of ice mass loss into northwest Greenland observed by GRACE and GPS

DEFF Research Database (Denmark)

Khan, Shfaqat Abbas; Wahr, John; Bevis, Michael

2010-01-01

Global Positioning System (GPS) measurements from three long-term sites on bedrock adjacent to the ice sheet. The GRACE results provide a direct measure of mass loss averaged over scales of a few hundred km. The GPS data are used to monitor crustal uplift caused by ice mass loss close to the sites....... The GRACE results can be used to predict crustal uplift, which can be compared with the GPS data. In addition to showing that the northwest ice sheet margin is now losing mass, the uplift results from both the GPS measurements and the GRACE predictions show rapid acceleration in southeast Greenland in late...... 2003, followed by a moderate deceleration in 2006. Because that latter deceleration is weak, southeast Greenland still appears to be losing ice mass at a much higher rate than it was prior to fall 2003. In a more general sense, the analysis described here demonstrates that GPS uplift measurements can...

Evaluation of recent GRACE monthly solution series with an ice sheet perspective

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Horwath, Martin; Groh, Andreas

2016-04-01

GRACE monthly global gravity field solutions have undergone a remarkable evolution, leading to the latest (Release 5) series by CSR, GFZ, and JPL, to new series by other processing centers, such as ITSG and AIUB, as well as to efforts to derive combined solutions, particularly by the EGSIEM (European Gravity Service for Improved Emergency Management) project. For applications, such as GRACE inferences on ice sheet mass balance, the obvious question is on what GRACE solution series to base the assessment. Here we evaluate different GRACE solution series (including the ones listed above) in a unified framework. We concentrate on solutions expanded up to degree 90 or higher, since this is most appropriate for polar applications. We empirically assess the error levels in the spectral as well as in the spatial domain based on the month-to-month scatter in the high spherical harmonic degrees. We include empirical assessment of error correlations. We then apply all series to infer Antarctic and Greenland mass change time series and compare the results in terms of apparent signal content and noise level. We find that the ITSG solutions show lowest noise level in the high degrees (above 60). A preliminary combined solution from the EGSIEM project shows lowest noise in the degrees below 60. This virtue maps into the derived ice mass time series, where the EGSIEM-based results show the lowest noise in most cases. Meanwhile, there is no indication that any of the considered series systematically dampens actual geophysical signals.

An Improved GRACE Terrestrial Water Storage Assimilation System For Estimating Large-Scale Soil Moisture and Shallow Groundwater

Science.gov (United States)

Girotto, M.; De Lannoy, G. J. M.; Reichle, R. H.; Rodell, M.

2015-12-01

The Gravity Recovery And Climate Experiment (GRACE) mission is unique because it provides highly accurate column integrated estimates of terrestrial water storage (TWS) variations. Major limitations of GRACE-based TWS observations are related to their monthly temporal and coarse spatial resolution (around 330 km at the equator), and to the vertical integration of the water storage components. These challenges can be addressed through data assimilation. To date, it is still not obvious how best to assimilate GRACE-TWS observations into a land surface model, in order to improve hydrological variables, and many details have yet to be worked out. This presentation discusses specific recent features of the assimilation of gridded GRACE-TWS data into the NASA Goddard Earth Observing System (GEOS-5) Catchment land surface model to improve soil moisture and shallow groundwater estimates at the continental scale. The major recent advancements introduced by the presented work with respect to earlier systems include: 1) the assimilation of gridded GRACE-TWS data product with scaling factors that are specifically derived for data assimilation purposes only; 2) the assimilation is performed through a 3D assimilation scheme, in which reasonable spatial and temporal error standard deviations and correlations are exploited; 3) the analysis step uses an optimized calculation and application of the analysis increments; 4) a poor-man's adaptive estimation of a spatially variable measurement error. This work shows that even if they are characterized by a coarse spatial and temporal resolution, the observed column integrated GRACE-TWS data have potential for improving our understanding of soil moisture and shallow groundwater variations.

On Graceful Spider Graphs with at Most Four Legs of Lengths Greater than One

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A. Panpa

2016-01-01

Full Text Available A graceful labeling of a tree T with n edges is a bijection f:V(T→{0,1,2,…,n} such that {|f(u-f(v|:uv∈E(T} equal to {1,2,…,n}. A spider graph is a tree with at most one vertex of degree greater than 2. We show that all spider graphs with at most four legs of lengths greater than one admit graceful labeling.

The potential of ground gravity measurements to validate GRACE data

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D. Crossley

2003-01-01

Full Text Available New satellite missions are returning high precision, time-varying, satellite measurements of the Earth’s gravity field. The GRACE mission is now in its calibration/- validation phase and first results of the gravity field solutions are imminent. We consider here the possibility of external validation using data from the superconducting gravimeters in the European sub-array of the Global Geodynamics Project (GGP as ‘ground truth’ for comparison with GRACE. This is a pilot study in which we use 14 months of 1-hour data from the beginning of GGP (1 July 1997 to 30 August 1998, when the Potsdam instrument was relocated to South Africa. There are 7 stations clustered in west central Europe, and one station, Metsahovi in Finland. We remove local tides, polar motion, local and global air pressure, and instrument drift and then decimate to 6-hour samples. We see large variations in the time series of 5–10µgal between even some neighboring stations, but there are also common features that correlate well over the 427-day period. The 8 stations are used to interpolate a minimum curvature (gridded surface that extends over the geographical region. This surface shows time and spatial coherency at the level of 2– 4µgal over the first half of the data and 1–2µgal over the latter half. The mean value of the surface clearly shows a rise in European gravity of about 3µgal over the first 150 days and a fairly constant value for the rest of the data. The accuracy of this mean is estimated at 1µgal, which compares favorably with GRACE predictions for wavelengths of 500 km or less. Preliminary studies of hydrology loading over Western Europe shows the difficulty of correlating the local hydrology, which can be highly variable, with large-scale gravity variations.Key words. GRACE, satellite gravity, superconducting gravimeter, GGP, ground truth

Rezension von: Catherine M. Orr, Ann Braithwaite, Diane Lichtenstein (Eds.: Rethinking Women’s and Gender Studies. London: Routledge 2012.

Directory of Open Access Journals (Sweden)

Jennifer Bühner

2014-03-01

Full Text Available Der Sammelband von Catherine M. Orr, Ann Braithwaite und Diane Lichtenstein bietet eine aktuelle Auseinandersetzung mit den zentralen Konzepten der Selbst-/Zuschreibung in den Women’s and Gender Studies (WGS im Kontext der gegenwärtigen Umstrukturierung der Universitäten – wie z. B. Methoden, Pädagogik, Community, Disziplin und Institutionalisierung. Dabei wird zum einen ein genealogischer Zugang gewählt, um die Funktionsweise dieser Konzepte aufzuzeigen, und zum anderen werden durch Selbstreflexion der Autor_innen auf ihre eigene Lehre und Position innerhalb der WGS Änderungsvorschläge eingebracht, um potentiell neue Richtungen für die Frauen- und Geschlechterforschung aufzuzeigen.

Improvements in GRACE Gravity Fields Using Regularization

Science.gov (United States)

Save, H.; Bettadpur, S.; Tapley, B. D.

2008-12-01

The unconstrained global gravity field models derived from GRACE are susceptible to systematic errors that show up as broad "stripes" aligned in a North-South direction on the global maps of mass flux. These errors are believed to be a consequence of both systematic and random errors in the data that are amplified by the nature of the gravity field inverse problem. These errors impede scientific exploitation of the GRACE data products, and limit the realizable spatial resolution of the GRACE global gravity fields in certain regions. We use regularization techniques to reduce these "stripe" errors in the gravity field products. The regularization criteria are designed such that there is no attenuation of the signal and that the solutions fit the observations as well as an unconstrained solution. We have used a computationally inexpensive method, normally referred to as "L-ribbon", to find the regularization parameter. This paper discusses the characteristics and statistics of a 5-year time-series of regularized gravity field solutions. The solutions show markedly reduced stripes, are of uniformly good quality over time, and leave little or no systematic observation residuals, which is a frequent consequence of signal suppression from regularization. Up to degree 14, the signal in regularized solution shows correlation greater than 0.8 with the un-regularized CSR Release-04 solutions. Signals from large-amplitude and small-spatial extent events - such as the Great Sumatra Andaman Earthquake of 2004 - are visible in the global solutions without using special post-facto error reduction techniques employed previously in the literature. Hydrological signals as small as 5 cm water-layer equivalent in the small river basins, like Indus and Nile for example, are clearly evident, in contrast to noisy estimates from RL04. The residual variability over the oceans relative to a seasonal fit is small except at higher latitudes, and is evident without the need for de-striping or

Recent changes in terrestrial water storage in the Upper Nile Basin: an evaluation of commonly used gridded GRACE products

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M. Shamsudduha

2017-09-01

Full Text Available GRACE (Gravity Recovery and Climate Experiment satellite data monitor large-scale changes in total terrestrial water storage (ΔTWS, providing an invaluable tool where in situ observations are limited. Substantial uncertainty remains, however, in the amplitude of GRACE gravity signals and the disaggregation of TWS into individual terrestrial water stores (e.g. groundwater storage. Here, we test the phase and amplitude of three GRACE ΔTWS signals from five commonly used gridded products (i.e. NASA's GRCTellus: CSR, JPL, GFZ; JPL-Mascons; GRGS GRACE using in situ data and modelled soil moisture from the Global Land Data Assimilation System (GLDAS in two sub-basins (LVB: Lake Victoria Basin; LKB: Lake Kyoga Basin of the Upper Nile Basin. The analysis extends from January 2003 to December 2012, but focuses on a large and accurately observed reduction in ΔTWS of 83 km3 from 2003 to 2006 in the Lake Victoria Basin. We reveal substantial variability in current GRACE products to quantify the reduction of ΔTWS in Lake Victoria that ranges from 80 km3 (JPL-Mascons to 69 and 31 km3 for GRGS and GRCTellus respectively. Representation of the phase in TWS in the Upper Nile Basin by GRACE products varies but is generally robust with GRGS, JPL-Mascons, and GRCTellus (ensemble mean of CSR, JPL, and GFZ time-series data, explaining 90, 84, and 75 % of the variance respectively in "in situ" or "bottom-up" ΔTWS in the LVB. Resolution of changes in groundwater storage (ΔGWS from GRACE ΔTWS is greatly constrained by both uncertainty in changes in soil-moisture storage (ΔSMS modelled by GLDAS LSMs (CLM, NOAH, VIC and the low annual amplitudes in ΔGWS (e.g. 1.8–4.9 cm observed in deeply weathered crystalline rocks underlying the Upper Nile Basin. Our study highlights the substantial uncertainty in the amplitude of ΔTWS that can result from different data-processing strategies in commonly used, gridded GRACE products; this uncertainty is

Recent changes in terrestrial water storage in the Upper Nile Basin: an evaluation of commonly used gridded GRACE products

Science.gov (United States)

Shamsudduha, Mohammad; Taylor, Richard G.; Jones, Darren; Longuevergne, Laurent; Owor, Michael; Tindimugaya, Callist

2017-09-01

GRACE (Gravity Recovery and Climate Experiment) satellite data monitor large-scale changes in total terrestrial water storage (ΔTWS), providing an invaluable tool where in situ observations are limited. Substantial uncertainty remains, however, in the amplitude of GRACE gravity signals and the disaggregation of TWS into individual terrestrial water stores (e.g. groundwater storage). Here, we test the phase and amplitude of three GRACE ΔTWS signals from five commonly used gridded products (i.e. NASA's GRCTellus: CSR, JPL, GFZ; JPL-Mascons; GRGS GRACE) using in situ data and modelled soil moisture from the Global Land Data Assimilation System (GLDAS) in two sub-basins (LVB: Lake Victoria Basin; LKB: Lake Kyoga Basin) of the Upper Nile Basin. The analysis extends from January 2003 to December 2012, but focuses on a large and accurately observed reduction in ΔTWS of 83 km3 from 2003 to 2006 in the Lake Victoria Basin. We reveal substantial variability in current GRACE products to quantify the reduction of ΔTWS in Lake Victoria that ranges from 80 km3 (JPL-Mascons) to 69 and 31 km3 for GRGS and GRCTellus respectively. Representation of the phase in TWS in the Upper Nile Basin by GRACE products varies but is generally robust with GRGS, JPL-Mascons, and GRCTellus (ensemble mean of CSR, JPL, and GFZ time-series data), explaining 90, 84, and 75 % of the variance respectively in "in situ" or "bottom-up" ΔTWS in the LVB. Resolution of changes in groundwater storage (ΔGWS) from GRACE ΔTWS is greatly constrained by both uncertainty in changes in soil-moisture storage (ΔSMS) modelled by GLDAS LSMs (CLM, NOAH, VIC) and the low annual amplitudes in ΔGWS (e.g. 1.8-4.9 cm) observed in deeply weathered crystalline rocks underlying the Upper Nile Basin. Our study highlights the substantial uncertainty in the amplitude of ΔTWS that can result from different data-processing strategies in commonly used, gridded GRACE products; this uncertainty is disregarded in analyses of �

Statistically optimal estimation of Greenland Ice Sheet mass variations from GRACE monthly solutions using an improved mascon approach

Science.gov (United States)

Ran, J.; Ditmar, P.; Klees, R.; Farahani, H. H.

2018-03-01

We present an improved mascon approach to transform monthly spherical harmonic solutions based on GRACE satellite data into mass anomaly estimates in Greenland. The GRACE-based spherical harmonic coefficients are used to synthesize gravity anomalies at satellite altitude, which are then inverted into mass anomalies per mascon. The limited spectral content of the gravity anomalies is properly accounted for by applying a low-pass filter as part of the inversion procedure to make the functional model spectrally consistent with the data. The full error covariance matrices of the monthly GRACE solutions are properly propagated using the law of covariance propagation. Using numerical experiments, we demonstrate the importance of a proper data weighting and of the spectral consistency between functional model and data. The developed methodology is applied to process real GRACE level-2 data (CSR RL05). The obtained mass anomaly estimates are integrated over five drainage systems, as well as over entire Greenland. We find that the statistically optimal data weighting reduces random noise by 35-69%, depending on the drainage system. The obtained mass anomaly time-series are de-trended to eliminate the contribution of ice discharge and are compared with de-trended surface mass balance (SMB) time-series computed with the Regional Atmospheric Climate Model (RACMO 2.3). We show that when using a statistically optimal data weighting in GRACE data processing, the discrepancies between GRACE-based estimates of SMB and modelled SMB are reduced by 24-47%.

Monitoring Lakes in Africa with Altimetry and GRACE

Science.gov (United States)

Carabajal, C. C.; Boy, J. P.

2017-12-01

Thanks to more than two decades of radar altimetry measurements from TOPEX/POSEIDON, Jason 1, 2 and 3, ENVISAT and others, 18 Ice, Cloud and Land Elevation Satellite (ICESat) laser altimeter measurement campaigns over 6 years, and 15 years of Gravity Recovery And Climate Experiment (GRACE) observations, water levels changes of major lakes and reservoirs can be remotely measured regularly with unprecedented precision, facilitating monitoring of continental water storage variations. Smaller footprint laser altimeters like ICESat are more suitable for the retrieval of water level variations of small inland water bodies, better discriminating water returns when water height measurements have the potential to be contaminated by land or vegetation. Using imagery from the Moderate Resolution Imaging Spectroradiometer (MODIS) contemporaneous with the altimetry data collections, in combination with careful examination of the laser waveforms, one can better isolate returns form the water surface. Combining these altimetry observations, we derive and compare water height estimates for several lakes and reservoirs in Africa from radar and laser altimetry measurements, we estimate the surface extent of each individual water body from available MODIS imagery, and derive corresponding estimates of volume variations for each water body. Mass variations from time-variable gravity measurements from the GRACE mission, using the latest one-degree global iterated mascons solution from GSFC are then transformed into volume changes, assuming a constant density, and compared to altimetry plus imagery estimates. These methods demonstrate the power of combined observations to monitor water resources and facilitate their management. Upcoming laser altimetry missions like ICESat-2, with vastly improved coverage and temporal sampling, continuous observations, better measurements techniques, including inland water products specifically formulated for these applications, when combined with SWOT

Using Enhanced Grace Water Storage Data to Improve Drought Detection by the U.S. and North American Drought Monitors

Science.gov (United States)

Houborg, Rasmus; Rodell, Matthew; Lawrimore, Jay; Li, Bailing; Reichle, Rolf; Heim, Richard; Rosencrans, Matthew; Tinker, Rich; Famiglietti, James S.; Svoboda, Mark;

Mass Evolution of Mediterranean, Black, Red, and Caspian Seas from GRACE and Altimetry: Accuracy Assessment and Solution Calibration

Science.gov (United States)

Loomis, B. D.; Luthcke, S. B.

2016-01-01

We present new measurements of mass evolution for the Mediterranean, Black, Red, and Caspian Seas as determined by the NASA Goddard Space Flight Center (GSFC) GRACE time-variable global gravity mascon solutions. These new solutions are compared to sea surface altimetry measurements of sea level anomalies with steric corrections applied. To assess their accuracy, the GRACE and altimetry-derived solutions are applied to the set of forward models used by GSFC for processing the GRACE Level-1B datasets, with the resulting inter-satellite range acceleration residuals providing a useful metric for analyzing solution quality.

Analysis of seasonal position variation for selected GNSS sites in Poland using loading modelling and GRACE data

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Marcin Rajner

2017-07-01

Full Text Available In this study we compared weekly GNSS position time series with modelled values of crustal deformations on the basis of Gravity Recovery and Climate Experiment (GRACE data. The Global Navigation Satellite Systems (GNSS time series were taken from homogeneously reprocessed global network solutions within the International GNSS Service (IGS Reprocessing 1 project and from regional solutions performed by Warsaw University of Technology (WUT European Permanent Network (EPN Local Analysis Center (LAC within the EPN reprocessing project. Eight GNSS sites from the territory of Poland with observation timespans between 2.5 and 13 years were selected for this study. The Total Water Equivalent (TWE estimation from GRACE data was used to compute deformations using the Green's function formalism. High frequency components were removed from GRACE data to avoid aliasing problems. Since GRACE observes mainly the mass transport in continental storage of water, we also compared GRACE deformations and the GNSS position time series, with the deformations computed on the basis of a hydrosphere model. We used the output of Water GAP Hydrology Model (WGHM to compute deformations in the same manner as for the GRACE data. The WGHM gave slightly larger amplitudes than GNSS and GRACE. The atmospheric non-tidal loading effect was removed from GNSS position time series before comparing them with modelled deformations. The results confirmed that the major part of observed seasonal variations for GNSS vertical components can be attributed to the hydrosphere loading. The results for these components agree very well both in the amplitude and phase. The decrease in standard deviation of the residual GNSS position time series for vertical components corrected for the hydrosphere loading reached maximally 36% and occurred for all but one stations for both global and regional solutions. For horizontal components the amplitudes are about three times smaller than for vertical

Evaluating Greenland glacial isostatic adjustment corrections using GRACE, altimetry and surface mass balance data

International Nuclear Information System (INIS)

Sutterley, Tyler C; Velicogna, Isabella; Csatho, Beata; Rezvan-Behbahani, Soroush; Babonis, Greg; Van den Broeke, Michiel

2014-01-01

Glacial isostatic adjustment (GIA) represents a source of uncertainty for ice sheet mass balance estimates from the Gravity Recovery and Climate Experiment (GRACE) time-variable gravity measurements. We evaluate Greenland GIA corrections from Simpson et al (2009 Quat. Sci. Rev. 28 1631–57), A et al (2013 Geophys. J. Int. 192 557–72) and Wu et al (2010 Nature Geosci. 3 642–6) by comparing the spatial patterns of GRACE-derived ice mass trends calculated using the three corrections with volume changes from ICESat (Ice, Cloud, and land Elevation Satellite) and OIB (Operation IceBridge) altimetry missions, and surface mass balance products from the Regional Atmospheric Climate Model (RACMO). During the period September 2003–August 2011, GRACE ice mass changes obtained using the Simpson et al (2009 Quat. Sci. Rev. 28 1631–57) and A et al (2013 Geophys. J. Int. 192 557–72) GIA corrections yield similar spatial patterns and amplitudes, and are consistent with altimetry observations and surface mass balance data. The two GRACE estimates agree within 2% on average over the entire ice sheet, and better than 15% in four subdivisions of Greenland. The third GRACE estimate corrected using the (Wu et al 2010 Nature Geosci. 3 642–6)) GIA shows similar spatial patterns, but produces an average ice mass loss for the entire ice sheet that is 64 − 67 Gt yr −1 smaller. In the Northeast the recovered ice mass change is 46–49 Gt yr −1 (245–270%) more positive than that deduced from the other two corrections. By comparing the spatial and temporal variability of the GRACE estimates with trends of volume changes from altimetry and surface mass balance from RACMO, we show that the Wu et al (2010 Nature Geosci. 3 642–6) correction leads to a large mass increase in the Northeast that is inconsistent with independent observations. (paper)

Q&A: Grace Anne Koppel, Living Well with COPD

Science.gov (United States)

... their own lives back is the most rewarding thing we have ever done. Read More "The Challenge of COPD" Articles Q&A: Grace Anne Koppel, Living Well with COPD / What is COPD? / What Causes COPD? / Getting Tested / Am I at Risk? / COPD Quiz Fall ...

Quantifying Modern Recharge to the Nubian Sandstone Aquifer System: Inferences from GRACE and Land Surface Models

Science.gov (United States)

Mohamed, A.; Sultan, M.; Ahmed, M.; Yan, E.

2014-12-01

The Nubian Sandstone Aquifer System (NSAS) is shared by Egypt, Libya, Chad and Sudanand is one of the largest (area: ~ 2 × 106 km2) groundwater systems in the world. Despite its importance to the population of these countries, major hydrological parameters such as modern recharge and extraction rates remain poorly investigated given: (1) the large extent of the NSAS, (2) the absence of comprehensive monitoring networks, (3) the general inaccessibility of many of the NSAS regions, (4) difficulties in collecting background information, largely included in unpublished governmental reports, and (5) limited local funding to support the construction of monitoring networks and/or collection of field and background datasets. Data from monthly Gravity Recovery and Climate Experiment (GRACE) gravity solutions were processed (Gaussian smoothed: 100 km; rescaled) and used to quantify the modern recharge to the NSAS during the period from January 2003 to December 2012. To isolate the groundwater component in GRACE data, the soil moisture and river channel storages were removed using the outputs from the most recent Community Land Model version 4.5 (CLM4.5). GRACE-derived recharge calculations were performed over the southern NSAS outcrops (area: 835 × 103 km2) in Sudan and Chad that receive average annual precipitation of 65 km3 (77.5 mm). GRACE-derived recharge rates were estimated at 2.79 ± 0.98 km3/yr (3.34 ± 1.17 mm/yr). If we take into account the total annual extraction rates (~ 0.4 km3; CEDARE, 2002) from Chad and Sudan the average annual recharge rate for the NSAS could reach up to ~ 3.20 ± 1.18 km3/yr (3.84 ± 1.42 mm/yr). Our recharge rates estimates are similar to those calculated using (1) groundwater flow modelling in the Central Sudan Rift Basins (4-8 mm/yr; Abdalla, 2008), (2) WaterGAP global scale groundwater recharge model (plans are underway for the deployment of a GRACE follow-On and GRACE-II missions, we suggest that within the next few years, GRACE

High-Resolution Assimilation of GRACE Terrestrial Water Storage Observations to Represent Local-Scale Water Table Depths

Science.gov (United States)

Stampoulis, D.; Reager, J. T., II; David, C. H.; Famiglietti, J. S.; Andreadis, K.

2017-12-01

Despite the numerous advances in hydrologic modeling and improvements in Land Surface Models, an accurate representation of the water table depth (WTD) still does not exist. Data assimilation of observations of the joint NASA and DLR mission, Gravity Recovery and Climate Experiment (GRACE) leads to statistically significant improvements in the accuracy of hydrologic models, ultimately resulting in more reliable estimates of water storage. However, the usually shallow groundwater compartment of the models presents a problem with GRACE assimilation techniques, as these satellite observations account for much deeper aquifers. To improve the accuracy of groundwater estimates and allow the representation of the WTD at fine spatial scales we implemented a novel approach that enables a large-scale data integration system to assimilate GRACE data. This was achieved by augmenting the Variable Infiltration Capacity (VIC) hydrologic model, which is the core component of the Regional Hydrologic Extremes Assessment System (RHEAS), a high-resolution modeling framework developed at the Jet Propulsion Laboratory (JPL) for hydrologic modeling and data assimilation. The model has insufficient subsurface characterization and therefore, to reproduce groundwater variability not only in shallow depths but also in deep aquifers, as well as to allow GRACE assimilation, a fourth soil layer of varying depth ( 1000 meters) was added in VIC as the bottom layer. To initialize a water table in the model we used gridded global WTD data at 1 km resolution which were spatially aggregated to match the model's resolution. Simulations were then performed to test the augmented model's ability to capture seasonal and inter-annual trends of groundwater. The 4-layer version of VIC was run with and without assimilating GRACE Total Water Storage anomalies (TWSA) over the Central Valley in California. This is the first-ever assimilation of GRACE TWSA for the determination of realistic water table depths, at

Estimating geocenter motion and barystatic sea-level variability from GRACE observations with explicit consideration of self-attraction and loading effects

Science.gov (United States)

Bergmann-Wolf, Inga; Dobslaw, Henryk

2016-04-01

Estimating global barystatic sea-level variations from monthly mean gravity fields delivered by the Gravity Recovery and Climate Experiment (GRACE) satellite mission requires additional information about geocenter motion. These variations are not available directly due to the mission implementation in the CM-frame and are represented by the degree-1 terms of the spherical harmonics expansion. Global degree-1 estimates can be determined with the method of Swenson et al. (2008) from ocean mass variability, the geometry of the global land-sea distribution, and GRACE data of higher degrees and orders. Consequently, a recursive relation between the derivation of ocean mass variations from GRACE data and the introduction of geocenter motion into GRACE data exists. In this contribution, we will present a recent improvement to the processing strategy described in Bergmann-Wolf et al. (2014) by introducing a non-homogeneous distribution of global ocean mass variations in the geocenter motion determination strategy, which is due to the effects of loading and self-attraction induced by mass redistributions at the surface. A comparison of different GRACE-based oceanographic products (barystatic signal for both the global oceans and individual basins; barotropic transport variations of major ocean currents) with degree-1 terms estimated with a homogeneous and non-homogeneous ocean mass representation will be discussed, and differences in noise levels in most recent GRACE solutions from GFZ (RL05a), CSR, and JPL (both RL05) and their consequences for the application of this method will be discussed. Swenson, S., D. Chambers and J. Wahr (2008), Estimating geocenter variations from a combination of GRACE and ocean model output, J. Geophys. Res., 113, B08410 Bergmann-Wolf, I., L. Zhang and H. Dobslaw (2014), Global Eustatic Sea-Level Variations for the Approximation of Geocenter Motion from GRACE, J. Geod. Sci., 4, 37-48

Relation of the aortic stiffness with the GRACE risk score in patients with the non ST-segment elevation myocardial infarction.

Science.gov (United States)

Omer, Gedikli; Gokhan, Aksan; Adem, Uzun; Sabri, Demircan; Korhan, Soylu

2014-01-01

Current guidelines recommend clinical risk scoring systems for the patients diagnosed and determinated treatment strategy with in Non-ST-elevation elevation myocardial infarction (NSTEMI). Previous studies demonstrated association between aortic elasticity properties, stiffness and severity CAD. However, the associations between Aortic stiffness, elasticity properties and clinical risk scores have not been investigated. In the present study we have evaluated the relation between the Global Registry of Acute Coronary Events (GRACE) risk score and aortic stiffness in patients with NSTEMI. We prospectively analyzed 87 consecutive patients with NSTEMI. Aortic elastic parameter and stiffness parameter were calculated from the echocardiographically derived thoracic aortic diameters (mm/m(2)), and the measurement of pulse pressure obtained by cuff sphygmomanometry. We have categorized the patients in to two groups as low ((n = 45) (GRACE risk score ≤ 140)) and high ((n = 42) (GRACE risk score > 140)) risk group according to GRACE risk score and compare the both groups. Table 1 shows baseline characteristics of patients. Our study showed that Aortic strain was significantly low (3.5 ± 1.4, 7.9 ± 2.3 respectively, p < 0.001) and aortic stiffness index was significantly high (3.9 ± 0.38; 3 ± 0.35, respectively, p < 0.001) in the high risk group values compared to those with low risk group. The aortic stiffness index was the only independent predictor of GRACE risk score (OR: 119.390; 95% CI: 2.925-4872.8; p = 0.011) in multivariate analysis. We found a significant correlation between aortic stiffness, impaired elasticity and GRACE risk score. Aortic stiffness index was the only independent variable of the high GRACE risk score. The inclusion of aortic stiffness into the GRACE risk score could allow improved risk classification of patients with ACS at admission and this may be important in the diagnosis, follow up and treatment of the patients.

The anxiety of learning. Interview by Diane L. Coutu.

Science.gov (United States)

Schein, Edgar H

2002-03-01

Despite all the time, money, and energy that executives pour into corporate change programs, the stark reality is that few companies ever succeed in genuinely reinventing themselves. That's because the people at those companies rarely master the art of transformational learning--that is, eagerly challenging deeply held assumptions about a company's processes and, in response, altering their thoughts and actions. Instead, most people just end up doing the same old things in superficially tweaked ways. Why is transformational learning so hard to achieve? HBR senior editor Diane Coutu explores this question with psychologist and MIT professor Edgar Schein, a world-renowned expert on organizational development. In sharp contrast to the optimistic rhetoric that permeates the debate on corporate learning and change, Schein is cautious about what companies can and cannot accomplish. Corporate culture can change, he says, but this kind of learning takes time, and it isn't fun. Learning is a coercive process, Schein argues, that requires blood, sweat, tears, and a certain level of anxiety to achieve the desired effect. In this article, he describes two basic types of anxiety--learning anxiety and survival anxiety--that drive radical relearning in organizations. Schein's theories spring from his early research on how American prisoners of war in Korea had been brainwashed by their captors. He cites the parallels between the "coercive persuasion" tactics the Chinese communists used to control their prisoners (isolating powerful ones and overseeing all communications) and the corporate boot camps that American companies use to indoctrinate their managers. Indeed, heavy socialization is back in style in U.S. corporations today, Schein says, even if no one is calling it that.

Monitoring groundwater storage changes in the highly dynamic Bengal Basin: validation of GRACE measurements

Science.gov (United States)

Shamsudduha, M.; Taylor, R. G.; Longuevergne, L.

2011-12-01

Monitoring of spatio-temporal changes in terrestrial water storage (ΔTWS) provides valuable information regarding the basin-scale dynamics of hydrological systems. Recent satellite measurements of the ΔTWS under the Gravity Recovery and Climate Experiment (GRACE) enable the derivation of groundwater storage changes (ΔGWS) where in situ data are limited. In the well monitored and highly-dynamic Bengal Basin of Bangladesh, we test the ability of GRACE measurements to trace the seasonality and trend in groundwater storage associated with intensive groundwater abstraction for dry-season irrigation and wet-season (monsoonal) recharge. Two different GRACE products (CSR and GRGS) and data processing methods (gridded and spherical harmonics) are also compared. Results show that GRACE derived estimates of recent (2003 to 2007) ΔGWS correlate well (r=0.77 to 0.93, p-value CSR for these estimates. ΔGWS accounts for 44% of the total variation in ΔTWS in the Bengal Basin. Changes in surface water storage (ΔSWS) estimated from a network of 298 river gauging stations and soil moisture storage (ΔSMS) derived from Land Surface Models explain 22% and 33% of ΔTWS respectively. Groundwater depletion estimated from borehole hydrographs (-0.52±0.30 km3/yr) is within the range of satellite-derived estimates (-0.44 to -2.04 km3/yr) that result from uncertainty associated with ΔSMS (CLM, NOAH, VIC) and GRACE data processing techniques. Recent (2003 to 2007) estimates of groundwater depletion are substantially greater than the long-term (1985 to 2007) mean (-0.21±0.03 km3/yr) and are explained primarily by substantial increases in groundwater abstraction for the dry-season irrigation and drinking water supplies over the last two decades.

Downscaling GRACE Remote Sensing Datasets to High-Resolution Groundwater Storage Change Maps of California’s Central Valley

Directory of Open Access Journals (Sweden)

Michelle E. Miro

2018-01-01

Full Text Available NASA’s Gravity Recovery and Climate Experiment (GRACE has already proven to be a powerful data source for regional groundwater assessments in many areas around the world. However, the applicability of GRACE data products to more localized studies and their utility to water management authorities have been constrained by their limited spatial resolution (~200,000 km2. Researchers have begun to address these shortcomings with data assimilation approaches that integrate GRACE-derived total water storage estimates into complex regional models, producing higher-resolution estimates of hydrologic variables (~2500 km2. Here we take those approaches one step further by developing an empirically based model capable of downscaling GRACE data to a high-resolution (~16 km2 dataset of groundwater storage changes over a portion of California’s Central Valley. The model utilizes an artificial neural network to generate a series of high-resolution maps of groundwater storage change from 2002 to 2010 using GRACE estimates of variations in total water storage and a series of widely available hydrologic variables (PRISM precipitation and temperature data, digital elevation model (DEM-derived slope, and Natural Resources Conservation Service (NRCS soil type. The neural network downscaling model is able to accurately reproduce local groundwater behavior, with acceptable Nash-Sutcliffe efficiency (NSE values for calibration and validation (ranging from 0.2445 to 0.9577 and 0.0391 to 0.7511, respectively. Ultimately, the model generates maps of local groundwater storage change at a 100-fold higher resolution than GRACE gridded data products without the use of computationally intensive physical models. The model’s simulated maps have the potential for application to local groundwater management initiatives in the region.

Seasonal Mass Changes in the Red Sea Observed By GPS and Grace

Science.gov (United States)

Alothman, A. O.; Fing, W.; Fernandes, R. M. S.; Bos, M. S.; Elsaka, B.

2014-12-01

The Red Sea is a semi-enclosed basin and exchanges water with the Gulf of Aden through the strait of Bab-el-Mandeb at the southern part of the sea. Its circulation is affected by the Indian Monsoon through its connection via the Gulf of Aden. Two distinctive (in summer and in winter) seasonal signals represent the water exchange. To understand the seasonal mass changes in the Red Sea, estimates of the mass changes based on two geodetic techniques are presented: from the Gravity Recovery and Climate Experiment (GRACE) and from the Global Navigation Satellite System (GNSS). The GRACE solutions were truncated up to spherical harmonic degree and order degree 60 to estimate the average monthly mass change in the atmosphere and ocean from models (several hours). GNSS solution is based on observations from four stations along the Red Sea that have been acquired in continuous mode starting in 2007 (having at least 5 years' data-span). The time series analysis of the observed GNSS vertical deformation of these sites has been analyzed. The results revealed that the GNSS observed vertical loading agrees with the atmospheric loading (ATML) assuming that the hydrological signal along the costs of the Red sea is negligible. Computed values of daily vertical atmospheric loading using the NCEP surface pressure data (Inverted Barometer IB) for the 4 stations for 2003 until 2013 are provided. Comparison of the GRACE and GNSS solutions has shown significant annual mass variations in the Red Sea (about 15 cm annual amplitude). After removing the atmospheric effect (ATML), the ocean loading can be observed by GNSS and GRACE estimates in the Red Sea.

Impact of combining GRACE and GOCE gravity data on ocean circulation estimates

Directory of Open Access Journals (Sweden)

T. Janjić

2012-02-01

Full Text Available With the focus on the Southern Ocean circulation, results of assimilation of multi-mission-altimeter data and the GRACE/GOCE gravity data into the finite element ocean model (FEOM are investigated. We use the geodetic method to obtain the dynamical ocean topography (DOT. This method combines the multi-mission-altimeter sea surface height and the GRACE/GOCE gravity field. Using the profile approach, the spectral consistency of both fields is achieved by filtering the sea surface height and the geoid. By combining the GRACE and GOCE data, a considerably shorter filter length can be used, which results in more DOT details. We show that this increase in resolution of measured DOT carries onto the results of data assimilation for the surface data. By assimilating only absolute dynamical topography data using the ensemble Kalman filter, we were able to improve modeled fields. Results are closer to observations which were not used for assimilation and lie outside the area covered by altimetry in the Southern Ocean (e.g. temperature of surface drifters or deep temperatures in the Weddell Sea area at 800 m depth derived from Argo composite.

Statistically optimal estimation of Greenland Ice Sheet mass variations from GRACE monthly solutions using an improved mascon approach

NARCIS (Netherlands)

Ran, J.; Ditmar, P.G.; Klees, R.; Farahani, H.

2017-01-01

We present an improved mascon approach to transform monthly spherical harmonic solutions based on GRACE satellite data into mass anomaly estimates in Greenland. The GRACE-based spherical harmonic coefficients are used to synthesize gravity anomalies at satellite altitude, which are then inverted

Detecting seasonal and long-term vertical displacement in the North China Plain using GRACE and GPS

Directory of Open Access Journals (Sweden)

L. Wang

2017-06-01

Full Text Available In total, 29 continuous Global Positioning System (GPS time series data together with data from Gravity Recovery and Climate Experiment (GRACE are analysed to determine the seasonal displacements of surface loadings in the North China Plain (NCP. Results show significant seasonal variations and a strong correlation between GPS and GRACE results in the vertical displacement component; the average correlation and weighted root-mean-squares (WRMS reduction between GPS and GRACE are 75.6 and 28.9 % respectively, when atmospheric and non-tidal ocean effects were removed, but the annual peak-to-peak amplitude of GPS (1.2–6.3 mm is greater than the data (1.0–2.2 mm derived from GRACE. We also calculate the trend rate as well as the seasonal signal caused by the mass load change from GRACE data; the rate of GRACE-derived terrestrial water storage (TWS loss (after multiplying by the scaling factor in the NCP was 3.39 cm yr−1 (equivalent to 12.42 km3 yr−1 from 2003 to 2009. For a 10-year time span (2003 to 2012, the rate loss of TWS was 2.57 cm yr−1 (equivalent to 9.41 km3 yr−1, which is consistent with the groundwater storage (GWS depletion rate (the rate losses of GWS were 2.49 and 2.72 cm yr−1 during 2003–2009 and 2003–2012 respectively estimated from GRACE-derived results after removing simulated soil moisture (SM data from the Global Land Data Assimilation System (GLDAS/Noah model. We also found that GRACE-derived GWS changes are in disagreement with the groundwater level changes from observations of shallow aquifers from 2003 to 2009, especially between 2010 and 2013. Although the shallow groundwater can be recharged from the annual climate-driven rainfall, the important facts indicate that GWS depletion is more serious in deep aquifers. The GRACE-derived result shows an overall uplift in the whole region at the 0.37–0.95 mm yr−1 level from 2004 to 2009, but the rate of change direction is

On the use of the GRACE normal equation of inter-satellite tracking data for estimation of soil moisture and groundwater in Australia

Directory of Open Access Journals (Sweden)

N. Tangdamrongsub

2018-03-01

Full Text Available An accurate estimation of soil moisture and groundwater is essential for monitoring the availability of water supply in domestic and agricultural sectors. In order to improve the water storage estimates, previous studies assimilated terrestrial water storage variation (ΔTWS derived from the Gravity Recovery and Climate Experiment (GRACE into land surface models (LSMs. However, the GRACE-derived ΔTWS was generally computed from the high-level products (e.g. time-variable gravity fields, i.e. level 2, and land grid from the level 3 product. The gridded data products are subjected to several drawbacks such as signal attenuation and/or distortion caused by a posteriori filters and a lack of error covariance information. The post-processing of GRACE data might lead to the undesired alteration of the signal and its statistical property. This study uses the GRACE least-squares normal equation data to exploit the GRACE information rigorously and negate these limitations. Our approach combines GRACE's least-squares normal equation (obtained from ITSG-Grace2016 product with the results from the Community Atmosphere Biosphere Land Exchange (CABLE model to improve soil moisture and groundwater estimates. This study demonstrates, for the first time, an importance of using the GRACE raw data. The GRACE-combined (GC approach is developed for optimal least-squares combination and the approach is applied to estimate the soil moisture and groundwater over 10 Australian river basins. The results are validated against the satellite soil moisture observation and the in situ groundwater data. Comparing to CABLE, we demonstrate the GC approach delivers evident improvement of water storage estimates, consistently from all basins, yielding better agreement on seasonal and inter-annual timescales. Significant improvement is found in groundwater storage while marginal improvement is observed in surface soil moisture estimates.

On the use of the GRACE normal equation of inter-satellite tracking data for estimation of soil moisture and groundwater in Australia

Science.gov (United States)

Tangdamrongsub, Natthachet; Han, Shin-Chan; Decker, Mark; Yeo, In-Young; Kim, Hyungjun

2018-03-01

An accurate estimation of soil moisture and groundwater is essential for monitoring the availability of water supply in domestic and agricultural sectors. In order to improve the water storage estimates, previous studies assimilated terrestrial water storage variation (ΔTWS) derived from the Gravity Recovery and Climate Experiment (GRACE) into land surface models (LSMs). However, the GRACE-derived ΔTWS was generally computed from the high-level products (e.g. time-variable gravity fields, i.e. level 2, and land grid from the level 3 product). The gridded data products are subjected to several drawbacks such as signal attenuation and/or distortion caused by a posteriori filters and a lack of error covariance information. The post-processing of GRACE data might lead to the undesired alteration of the signal and its statistical property. This study uses the GRACE least-squares normal equation data to exploit the GRACE information rigorously and negate these limitations. Our approach combines GRACE's least-squares normal equation (obtained from ITSG-Grace2016 product) with the results from the Community Atmosphere Biosphere Land Exchange (CABLE) model to improve soil moisture and groundwater estimates. This study demonstrates, for the first time, an importance of using the GRACE raw data. The GRACE-combined (GC) approach is developed for optimal least-squares combination and the approach is applied to estimate the soil moisture and groundwater over 10 Australian river basins. The results are validated against the satellite soil moisture observation and the in situ groundwater data. Comparing to CABLE, we demonstrate the GC approach delivers evident improvement of water storage estimates, consistently from all basins, yielding better agreement on seasonal and inter-annual timescales. Significant improvement is found in groundwater storage while marginal improvement is observed in surface soil moisture estimates.

The use of GRACE data to monitor natural and anthropogenic induced variations in water availability across Africa

Energy Technology Data Exchange (ETDEWEB)

Ahmed, Mohamed; Sultan, Mohamed; Wahr, John; Yan, Eugene

2014-05-27

Inter-annual trends in terrestrial water storage (TWS) were extracted from monthly (01/2003–09/2012) Gravity Recovery and Climate Experiment (GRACE) data acquired over Africa and correlated (in a geographic information system [GIS] environment) with relevant temporal remote sensing, geologic, and hydrologic datasets. Findings include the following: (1) large sectors of Africa are undergoing statistically significant TWS variations (+ 44 mm/yr to -15 mm/yr) due to natural and anthropogenic causes; (2) warming of the tropical Atlantic Ocean apparently intensified Atlantic monsoons and increased precipitation and TWS over western and central Africa; (3) warming in the central Indian Ocean decreased precipitation and TWS over eastern Africa; (4) the high frequency of flooding events increased TWS over the Zambezi and Okavango basins; (5) extraction of fossil groundwater decreased TWS over the Saharan aquifers; (6) deforestation decreased TWS in three subbasins (Ubangi, Congo, and Sangha) of the Congo River Basin; and (7) the construction of dams increased TWS in the Blue Nile and Atbara subbasins. Given the 10 years of monthly GRACE data acquired on the subbasin scale across the globe, as well as the plans underway for deployment of a GRACE-FO and GRACE-II, using GRACE-derived TWS data should be considered an alternative, viable index for measuring temporal and spatial variations in water availability.

Use of GRACE Terrestrial Water Storage Retrievals to Evaluate Model Estimates by the Australian Water Resources Assessment System

Science.gov (United States)

van Dijk, A. I. J. M.; Renzullo, L. J.; Rodell, M.

2011-01-01

Terrestrial water storage (TWS) estimates retrievals from the Gravity Recovery and Climate Experiment (GRACE) satellite mission were compared to TWS modeled by the Australian Water Resources Assessment (AWRA) system. The aim was to test whether differences could be attributed and used to identify model deficiencies. Data for 2003 2010 were decomposed into the seasonal cycle, linear trends and the remaining de-trended anomalies before comparing. AWRA tended to have smaller seasonal amplitude than GRACE. GRACE showed a strong (greater than 15 millimeter per year) drying trend in northwest Australia that was associated with a preceding period of unusually wet conditions, whereas weaker drying trends in the southern Murray Basin and southwest Western Australia were associated with relatively dry conditions. AWRA estimated trends were less negative for these regions, while a more positive trend was estimated for areas affected by cyclone Charlotte in 2009. For 2003-2009, a decrease of 7-8 millimeter per year (50-60 cubic kilometers per year) was estimated from GRACE, enough to explain 6-7% of the contemporary rate of global sea level rise. This trend was not reproduced by the model. Agreement between model and data suggested that the GRACE retrieval error estimates are biased high. A scaling coefficient applied to GRACE TWS to reduce the effect of signal leakage appeared to degrade quantitative agreement for some regions. Model aspects identified for improvement included a need for better estimation of rainfall in northwest Australia, and more sophisticated treatment of diffuse groundwater discharge processes and surface-groundwater connectivity for some regions.

3-D GRACE gravity model for the 2011 Japan earthquake

Indian Academy of Sciences (India)

Corresponding author. e-mail: rgss1fes@iitr.ac.in/rgssastry@gmail.com. The GRACE mission has contributed to the seismic characterization of major earthquakes in offshore ... −13μGal), fully accounting for co-seismic mass redistribution.

Grace announces coal-to-methanol project

Energy Technology Data Exchange (ETDEWEB)

Myers, R

1980-02-15

WR Grace and Co. are planning a feasibility study for a plant to produce 5000 tons/day of methanol and 6000 tons/day of carbon dioxide from captive coal reserves in Colorado. The study will be performed by Energy Transition Co. (ETCo). The producers would be used for pipeline transmission of pulverised coal, probably to California. At the destination the coal would go to a power station, the methanol to a gas turbine and the carbon dioxide to an oil producer for tertiary recovery.

Using an SLR inversion to measure the mass balance of Greenland before and during GRACE

Science.gov (United States)

Bonin, Jennifer

2016-04-01

The GRACE mission has done an admirable job of measuring large-scale mass changes over Greenland since its launch in 2002. However before that time, measurements of large-scale ice mass balance were few and far between, leading to a lack of baseline knowledge. High-quality Satellite Laser Ranging (SLR) data existed a decade earlier, but normally has too low a spatial resolution to be used for this purpose. I demonstrate that a least squares inversion technique can reconstitute the SLR data and use it to measure ice loss over Greenland. To do so, I first simulate the problem by degrading today's GRACE data to a level comparable with SLR, then demonstrating that the inversion can re-localize Greenland's contribution to the low-resolution signal, giving an accurate time series of mass change over all of Greenland which compares well with the full-resolution GRACE estimates. I then utilize that method on the actual SLR data, resulting in an independent 1994-2014 time series of mass change over Greenland. I find favorable agreement between the pure-SLR inverted results and the 2012 Ice-sheet Mass Balance Inter-comparison Exercise (IMBIE) results, which are largely based on the "input-output" modeling method before GRACE's launch.

"Amazing Grace": Literature as a Window on Colonial Slavery.

Science.gov (United States)

Basker, James G.

2003-01-01

Describes the book, "Amazing Grace: An Anthology of Poems about Slavery 1660-1810." Presents poems, written by 250 writers, that focus on slavery during the 150 year period. Provides examples of materials included in this book and how it can enable students to increase their understanding of slavery. (CMK)

Application of GRACE to the assessment of model-based estimates of monthly Greenland Ice Sheet mass balance (2003-2012)

Science.gov (United States)

Schlegel, Nicole-Jeanne; Wiese, David N.; Larour, Eric Y.; Watkins, Michael M.; Box, Jason E.; Fettweis, Xavier; van den Broeke, Michiel R.

2016-09-01

Quantifying the Greenland Ice Sheet's future contribution to sea level rise is a challenging task that requires accurate estimates of ice sheet sensitivity to climate change. Forward ice sheet models are promising tools for estimating future ice sheet behavior, yet confidence is low because evaluation of historical simulations is challenging due to the scarcity of continental-wide data for model evaluation. Recent advancements in processing of Gravity Recovery and Climate Experiment (GRACE) data using Bayesian-constrained mass concentration ("mascon") functions have led to improvements in spatial resolution and noise reduction of monthly global gravity fields. Specifically, the Jet Propulsion Laboratory's JPL RL05M GRACE mascon solution (GRACE_JPL) offers an opportunity for the assessment of model-based estimates of ice sheet mass balance (MB) at ˜ 300 km spatial scales. Here, we quantify the differences between Greenland monthly observed MB (GRACE_JPL) and that estimated by state-of-the-art, high-resolution models, with respect to GRACE_JPL and model uncertainties. To simulate the years 2003-2012, we force the Ice Sheet System Model (ISSM) with anomalies from three different surface mass balance (SMB) products derived from regional climate models. Resulting MB is compared against GRACE_JPL within individual mascons. Overall, we find agreement in the northeast and southwest where MB is assumed to be primarily controlled by SMB. In the interior, we find a discrepancy in trend, which we presume to be related to millennial-scale dynamic thickening not considered by our model. In the northwest, seasonal amplitudes agree, but modeled mass trends are muted relative to GRACE_JPL. Here, discrepancies are likely controlled by temporal variability in ice discharge and other related processes not represented by our model simulations, i.e., hydrological processes and ice-ocean interaction. In the southeast, GRACE_JPL exhibits larger seasonal amplitude than predicted by the

Numerical precision control and GRACE

International Nuclear Information System (INIS)

Fujimoto, J.; Hamaguchi, N.; Ishikawa, T.; Kaneko, T.; Morita, H.; Perret-Gallix, D.; Tokura, A.; Shimizu, Y.

2006-01-01

The control of the numerical precision of large-scale computations like those generated by the GRACE system for automatic Feynman diagram calculations has become an intrinsic part of those packages. Recently, Hitachi Ltd. has developed in FORTRAN a new library HMLIB for quadruple and octuple precision arithmetic where the number of lost-bits is made available. This library has been tested with success on the 1-loop radiative correction to e + e - ->e + e - τ + τ - . It is shown that the approach followed by HMLIB provides an efficient way to track down the source of numerical significance losses and to deliver high-precision results yet minimizing computing time

The celestial mechanics approach: application to data of the GRACE mission

Science.gov (United States)

Beutler, Gerhard; Jäggi, Adrian; Mervart, Leoš; Meyer, Ulrich

2010-11-01

The celestial mechanics approach (CMA) has its roots in the Bernese GPS software and was extensively used for determining the orbits of high-orbiting satellites. The CMA was extended to determine the orbits of Low Earth Orbiting satellites (LEOs) equipped with GPS receivers and of constellations of LEOs equipped in addition with inter-satellite links. In recent years the CMA was further developed and used for gravity field determination. The CMA was developed by the Astronomical Institute of the University of Bern (AIUB). The CMA is presented from the theoretical perspective in (Beutler et al. 2010). The key elements of the CMA are illustrated here using data from 50 days of GPS, K-Band, and accelerometer observations gathered by the Gravity Recovery And Climate Experiment (GRACE) mission in 2007. We study in particular the impact of (1) analyzing different observables [Global Positioning System (GPS) observations only, inter-satellite measurements only], (2) analyzing a combination of observations of different types on the level of the normal equation systems (NEQs), (3) using accelerometer data, (4) different orbit parametrizations (short-arc, reduced-dynamic) by imposing different constraints on the stochastic orbit parameters, and (5) using either the inter-satellite ranges or their time derivatives. The so-called GRACE baseline, i.e., the achievable accuracy of the GRACE gravity field for a particular solution strategy, is established for the CMA.

"A Prairie Childhood" by Edith Abbott: An Excerpt from "The Children's Champion," a Biography of Grace Abbott

Science.gov (United States)

Sorensen, John

2003-01-01

Grace Abbott's courageous struggles--to protect the rights of immigrants, to increase the role of women in government, and to improve the lives of all children--are filled with adventurous tales of the remarkable human ability to seek out suffering and to do something about it. "A Prairie Childhood" is an excerpt from the Grace Abbott biography…

Earth Surface Deformation in the North China Plain Detected by Joint Analysis of GRACE and GPS Data

Science.gov (United States)

Liu, Renli; Li, Jiancheng; Fok, Hok Sum; Shum, C.K.; Li, Zhao

2014-01-01

Mass redistribution of the Earth causes variable loading that deforms the solid Earth. While most recent studies using geodetic techniques focus on regions (such as the Amazon basin and the Nepal Himalayas) with large seasonal deformation amplitudes on the order of 1–4 cm due to hydrologic loading, few such studies have been conducted on the regions where the seasonal deformation amplitude is half as large. Here, we use joint GPS and GRACE data to investigate the vertical deformation due to hydrologic loading in the North China Plain, where significant groundwater depletion has been reported. We found that the GPS- and GRACE-derived secular trends and seasonal signals are in good agreement, with an uplift magnitude of 1–2 mm/year and a correlation of 85.0%–98.5%, respectively. This uplift rate is consistent with groundwater depletion rate estimated from GRACE data and in-situ groundwater measurements from earlier report studies; whereas the seasonal hydrologic variation reflects human behavior of groundwater pumping for agriculture irrigation in spring, leading to less water storage in summer than that in the winter season. However, less than 20% of weighted root-mean-squared (WRMS) reductions were detected for all the selected GPS stations when GRACE-derived seasonal deformations were removed from detrended GPS height time series. This discrepancy is probably because the GRACE-derived seasonal signals are large-scale, while the GPS-derived signals are local point measurements. PMID:25340454

Earth surface deformation in the North China Plain detected by joint analysis of GRACE and GPS data.

Science.gov (United States)

Liu, Renli; Li, Jiancheng; Fok, Hok Sum; Shum, C K; Li, Zhao

2014-10-22

Mass redistribution of the Earth causes variable loading that deforms the solid Earth. While most recent studies using geodetic techniques focus on regions (such as the Amazon basin and the Nepal Himalayas) with large seasonal deformation amplitudes on the order of 1-4 cm due to hydrologic loading, few such studies have been conducted on the regions where the seasonal deformation amplitude is half as large. Here, we use joint GPS and GRACE data to investigate the vertical deformation due to hydrologic loading in the North China Plain, where significant groundwater depletion has been reported. We found that the GPS- and GRACE-derived secular trends and seasonal signals are in good agreement, with an uplift magnitude of 1-2 mm/year and a correlation of 85.0%-98.5%, respectively. This uplift rate is consistent with groundwater depletion rate estimated from GRACE data and in-situ groundwater measurements from earlier report studies; whereas the seasonal hydrologic variation reflects human behavior of groundwater pumping for agriculture irrigation in spring, leading to less water storage in summer than that in the winter season. However, less than 20% of weighted root-mean-squared (WRMS) reductions were detected for all the selected GPS stations when GRACE-derived seasonal deformations were removed from detrended GPS height time series. This discrepancy is probably because the GRACE-derived seasonal signals are large-scale, while the GPS-derived signals are local point measurements.

Mass balance of Greenland and the Canadian Ice Caps from combined altimetry and GRACE inversion

DEFF Research Database (Denmark)

Forsberg, René; Simonsen, Sebastian Bjerregaard; Sørensen, Louise Sandberg

The combination of GRACE and altimetry data may yield a high resolution mass balance time series of the Greenlandice sheet, highlighting the varying individual mass loss behaviour of major glaciers. By including the Canadian arctic ice caps in the estimation, a more reliable estimate of the mass...... loss of both Greenlandand the Canadian ice caps may be obtained, minimizing the leakage errors otherwise unavoidable by GRACE. Actually, the absolute value of the Greenlandice sheet mass loss is highly dependent on methods and how the effects of Arctic Canadian ice caps are separated in the GRACE...... loss of the ice caps and ice sheet basins for the period 2003-15. This period shows a marked increase of ice sheet melt, especially in NW and NE Greenland, but also show large variability, with the melt anomaly year of 2012 showing a record mass loss, followed by 2013 with essentially no Greenland mass...

Groundwater Withdrawals under Drought: Reconciling GRACE and Models in the United States High Plains Aquifer

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Nie, W.; Zaitchik, B. F.; Kumar, S.; Rodell, M.

2017-12-01

Advanced Land Surface Models (LSM) offer a powerful tool for studying and monitoring hydrological variability. Highly managed systems, however, present a challenge for these models, which typically have simplified or incomplete representations of human water use, if the process is represented at all. GRACE, meanwhile, detects the total change in water storage, including change due to human activities, but does not resolve the source of these changes. Here we examine recent groundwater declines in the US High Plains Aquifer (HPA), a region that is heavily utilized for irrigation and that is also affected by episodic drought. To understand observed decline in groundwater (well observation) and terrestrial water storage (GRACE) during a recent multi-year drought, we modify the Noah-MP LSM to include a groundwater pumping irrigation scheme. To account for seasonal and interannual variability in active irrigated area we apply a monthly time-varying greenness vegetation fraction (GVF) dataset to the model. A set of five experiments were performed to study the impact of irrigation with groundwater withdrawal on the simulated hydrological cycle of the HPA and to assess the importance of time-varying GVF when simulating drought conditions. The results show that including the groundwater pumping irrigation scheme in Noah-MP improves model agreement with GRACE mascon solutions for TWS and well observations of groundwater anomaly in the southern HPA, including Texas and Kansas, and that accounting for time-varying GVF is important for model realism under drought. Results for the HPA in Nebraska are mixed, likely due to misrepresentation of the recharge process. This presentation will highlight the value of the GRACE constraint for model development, present estimates of the relative contribution of climate variability and irrigation to declining TWS in the HPA under drought, and identify opportunities to integrate GRACE-FO with models for water resource monitoring in heavily

The potential of GRACE gravimetry to detect the heavy rainfall-induced impoundment of a small reservoir in the upper Yellow River

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Yi, Shuang; Song, Chunqiao; Wang, Qiuyu; Wang, Linsong; Heki, Kosuke; Sun, Wenke

2017-08-01

Artificial reservoirs are important indicators of anthropogenic impacts on environments, and their cumulative influences on the local water storage will change the gravity signal. However, because of their small signal size, such gravity changes are seldom studied using satellite gravimetry from the Gravity Recovery and Climate Experiment (GRACE). Here we investigate the ability of GRACE to detect water storage changes in the Longyangxia Reservoir (LR), which is situated in the upper main stem of the Yellow River. Three different GRACE solutions from the CSR, GFZ, and JPL with three different processing filters are compared here. We find that heavy precipitation in the summer of 2005 caused the LR water storage to increase by 37.9 m in height, which is equivalent to 13.0 Gt in mass, and that the CSR solutions with a DDK4 filter show the best performance in revealing the synthetic gravity signals. We also obtain 109 pairs of reservoir inundation area measurements from satellite imagery and water level changes from laser altimetry and in situ observations to derive the area-height ratios for the LR. The root mean square of GRACE series in the LR is reduced by 39% after removing synthetic signals caused by mass changes in the LR or by 62% if the GRACE series is further smoothed. We conclude that GRACE data show promising potential in detecting water storage changes in this ˜400 km2 reservoir and that a small signal size is not a restricting factor for detection using GRACE data.

Attention, Asceticism, and Grace: Simone Weil and Higher Education

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Roberts, Peter

2011-01-01

The work of the French thinker Simone Weil has exerted an important influence on scholars in a wide range of fields. To date, however, her writings have attracted comparatively little interest from educationists. This article discusses some of the key concepts in Weil's philosophy--gravity, grace, decreation, and attention--and assesses their…

Product shipping information using graceful labeling on undirected tree graph approach

Science.gov (United States)

Kuan, Yoong Kooi; Ghani, Ahmad Termimi Ab

2017-08-01

Product shipping information is the related information of an ordered product that ready to be shipped to the foreign customer's company, where the information represents as an irrefutable proof in black and white to the local manufacturer by E-mails. This messy and unordered list of information is stored in E-mail folders by the people incharge, which do not function in collating the information properly. So, in this paper, an algorithm is proposed on how to rearrange the messy information from the sequence of a path graph structure into a concise version of a caterpillar graph with achieving the concept of graceful labeling. The final graceful caterpillar graph consists of the full listed information together with the numbering, which able to assist people get the information fleetly for shipping arrangement procedure.

Evaluating short-term hydro-meteorological fluxes using GRACE-derived water storage changes

Science.gov (United States)

Eicker, A.; Jensen, L.; Springer, A.; Kusche, J.

2017-12-01

Atmospheric and terrestrial water budgets, which represent important boundary conditions for both climate modeling and hydrological studies, are linked by evapotranspiration (E) and precipitation (P). These fields are provided by numerical weather prediction models and atmospheric reanalyses such as ERA-Interim and MERRA-Land; yet, in particular the quality of E is still not well evaluated. Via the terrestrial water budget equation, water storage changes derived from products of the Gravity Recovery and Climate Experiment (GRACE) mission, combined with runoff (R) data can be used to assess the realism of atmospheric models. In this contribution we will investigate the closure of the water balance for short-term fluxes, i.e. the agreement of GRACE water storage changes with P-E-R flux time series from different (global and regional) atmospheric reanalyses, land surface models, as well as observation-based data sets. Missing river runoff observations will be extrapolated using the calibrated rainfall-runoff model GR2M. We will perform a global analysis and will additionally focus on selected river basins in West Africa. The investigations will be carried out for various temporal scales, focusing on short-term fluxes down to daily variations to be detected in daily GRACE time series.

Assimilation of GRACE Terrestrial Water Storage into a Land Surface Model: Evaluation 1 and Potential Value for Drought Monitoring in Western and Central Europe

Science.gov (United States)

Li, Bailing; Rodell, Matthew; Zaitchik, Benjamin F.; Reichle, Rolf H.; Koster, Randal D.; van Dam, Tonie M.

2012-01-01

A land surface model s ability to simulate states (e.g., soil moisture) and fluxes (e.g., runoff) is limited by uncertainties in meteorological forcing and parameter inputs as well as inadequacies in model physics. In this study, anomalies of terrestrial water storage (TWS) observed by the Gravity Recovery and Climate Experiment (GRACE) satellite mission were assimilated into the NASA Catchment land surface model in western and central Europe for a 7-year period, using a previously developed ensemble Kalman smoother. GRACE data assimilation led to improved runoff correlations with gauge data in 17 out of 18 hydrological basins, even in basins smaller than the effective resolution of GRACE. Improvements in root zone soil moisture were less conclusive, partly due to the shortness of the in situ data record. In addition to improving temporal correlations, GRACE data assimilation also reduced increasing trends in simulated monthly TWS and runoff associated with increasing rates of precipitation. GRACE assimilated root zone soil moisture and TWS fields exhibited significant changes in their dryness rankings relative to those without data assimilation, suggesting that GRACE data assimilation could have a substantial impact on drought monitoring. Signals of drought in GRACE TWS correlated well with MODIS Normalized Difference Vegetation Index (NDVI) data in most areas. Although they detected the same droughts during warm seasons, drought signatures in GRACE derived TWS exhibited greater persistence than those in NDVI throughout all seasons, in part due to limitations associated with the seasonality of vegetation.

Antarctic contribution to sea level rise observed by GRACE with improved GIA correction

Science.gov (United States)

Ivins, Erik R.; James, Thomas S.; Wahr, John; Schrama, Ernst J. O.; Landerer, Felix W.; Simon, Karen M.

2013-06-01

Antarctic volume changes during the past 21 thousand years are smaller than previously thought, and here we construct an ice sheet history that drives a forward model prediction of the glacial isostatic adjustment (GIA) gravity signal. The new model, in turn, should give predictions that are constrained with recent uplift data. The impact of the GIA signal on a Gravity Recovery and Climate Experiment (GRACE) Antarctic mass balance estimate depends on the specific GRACE analysis method used. For the method described in this paper, the GIA contribution to the apparent surface mass change is re-evaluated to be +55±13 Gt/yr by considering a revised ice history model and a parameter search for vertical motion predictions that best fit the GPS observations at 18 high-quality stations. Although the GIA model spans a range of possible Earth rheological structure values, the data are not yet sufficient for solving for a preferred value of upper and lower mantle viscosity nor for a preferred lithospheric thickness. GRACE monthly solutions from the Center for Space Research Release 04 (CSR-RL04) release time series from January 2003 to the beginning of January 2012, uncorrected for GIA, yield an ice mass rate of +2.9± 29 Gt/yr. The new GIA correction increases the solved-for ice mass imbalance of Antarctica to -57±34 Gt/yr. The revised GIA correction is smaller than past GRACE estimates by about 50 to 90 Gt/yr. The new upper bound to the sea level rise from the Antarctic ice sheet, averaged over the time span 2003.0-2012.0, is about 0.16±0.09 mm/yr.

Evaluating Renewable Groundwater Stress with GRACE data in Greece

Science.gov (United States)

Lakshmi, V.; Gemitzi, A.

2016-12-01

Groundwater is a resilient water source and its importance as a fundamental resource is even greater in times of drought where groundwater stress conditions are greatest for areas like Mediterranean and adverse climate change effects are expected. The present study evaluates Renewable Groundwater Stress (RGS) as the ratio of groundwater use to groundwater availability, quantifying use as the trend in GRACE-derived subsurface anomalies (ΔGWtrend) and renewable groundwater availability as mean annual recharge. Estimates for mean annual recharge were used from groundwater studies conducted for the various regions in Greece, mainly in the form of numerical models. Our results highlighted two RGS regimes in Greece out of the four characteristic stress regimes, i.e. Overstressed, Variable Stress, Human-Dominated Stress and Unstressed, defined as a function of the sign of use and the sign of groundwater availability (positive or negative). Variable Stress areas are found in central Greece (Thessaly region), where intense agricultural activities take place, with negative ΔGWtrend values combined with positive mean annual recharge rates. RGS values range from -0.05 - 0, indicating however a low impact area. Within this region, adverse effects of groundwater overexploitation are already evident, based on the negative GRACE anomalies, recharge however still remains positive, amending the adverse over pumping impacts. The rest of Greek aquifers fall within the unstressed category, with RGS values from 0.02 - 0.05, indicating that the rate of use is less than the natural recharge rate. The highest Unstressed RGS values are observed in Crete Island and in Northeastern Greece. However, the case of Crete is highly uncertain, as precipitation and recharge in this area demonstrate exceptionally high variability and the coarse resolution of GRACE results does not allow for reliable estimates.

Resolving mass flux at high spatial and temporal resolution using GRACE intersatellite measurements

DEFF Research Database (Denmark)

Rowlands, D. D.; Luthcke, S. B.; Klosko, S. M.

2005-01-01

resolution. Using 4° × 4° blocks at 10-day intervals, we estimate the mass of surplus or deficit water over a 52° × 60° grid centered on the Amazon basin for July 2003. We demonstrate that the recovered signals are coherent and correlate well with the expected hydrological signal....... the estimation of static monthly parameters. Through an analysis of the GRACE data residuals, we show that the fundamental temporal and spatial resolution of the GRACE data is 10 days and 400 km. We present an approach similar in concept to altimetric methods that recovers submonthly mass flux at a high spatial...

Quantifying the resolution level where the GRACE satellites can separate Greenland's glacial mass balance from surface mass balance

Science.gov (United States)

Bonin, J. A.; Chambers, D. P.

2015-09-01

Mass change over Greenland can be caused by either changes in the glacial dynamic mass balance (DMB) or the surface mass balance (SMB). The GRACE satellite gravity mission cannot directly separate the two physical causes because it measures the sum of the entire mass column with limited spatial resolution. We demonstrate one theoretical way to indirectly separate cumulative SMB from DMB with GRACE, using a least squares inversion technique with knowledge of the location of the glaciers. However, we find that the limited 60 × 60 spherical harmonic representation of current GRACE data does not provide sufficient resolution to adequately accomplish the task. We determine that at a maximum degree/order of 90 × 90 or above, a noise-free gravity measurement could theoretically separate the SMB from DMB signals. However, current GRACE satellite errors are too large at present to separate the signals. A noise reduction of a factor of 10 at a resolution of 90 × 90 would provide the accuracy needed for the interannual cumulative SMB and DMB to be accurately separated.

Characterizing Drought and Flood Events over the Yangtze River Basin Using the HUST-Grace2016 Solution and Ancillary Data

Directory of Open Access Journals (Sweden)

Hao Zhou

2017-10-01

Full Text Available Accurate terrestrial water storage (TWS estimation is important to evaluate the situation of the water resources over the Yangtze River Basin (YRB. This study exploits the TWS observation from the new temporal gravity field model, HUST-Grace2016 (Huazhong University of Science and Technology, which is developed by a new low-frequency noise processing strategy. A novel GRACE (Gravity Recovery and Climate Experiment post-processing approach is proposed to enhance the quality of the TWS estimate, and the improved TWS is used to characterize the drought and flood events over the YRB. The HUST-Grace2016-derived TWS presents good agreement with the CSR (Center for Space Research mascon solution as well as the PCR-GLOBWB (PCRaster Global Water Balance hydrological model. Particularly, our solution provides remarkable performance in identifying the extreme climate events e.g., flood and drought over the YRB and its sub-basins. The comparison between GRACE-derived TWS variations and the MODIS-derived (Moderate Resolution Imaging Spectroradiometer inundated area variations is then conducted. The analysis demonstrates that the terrestrial reflectance data can provide an alternative way of cross-comparing and validating TWS information in Poyang Lake and Dongting Lake, with a correlation coefficient of 0.77 and 0.70, respectively. In contrast, the correlation is only 0.10 for Tai Lake, indicating the limitation of cross-comparison between MODIS and GRACE data. In addition, for the first time, the NCEP/NCAR (National Centers for Environmental Prediction/National Center for Atmospheric Research vertical velocity data is incorporated with GRACE TWS in the exploration of the climate-induced hydrological activities. The good agreement between non-seasonal NCEP/NCAR vertical velocities and non-seasonal GRACE TWSs is found in flood years (2005, 2010, 2012 and 2016 and drought years (2006, 2011 and 2013. The evidence shown in this study may contribute to the

Estimating Antarctica land topography from GRACE gravity and ICESat altimetry data

Science.gov (United States)

Wu, I.; Chao, B. F.; Chen, Y.

2009-12-01

We propose a new method combining GRACE (Gravity Recovery and Climate Experiment) gravity and ICESat (Ice, Cloud, and land Elevation Satellite) altimetry data to estimate the land topography for Antarctica. Antarctica is the fifth-largest continent in the world and about 98% of Antarctica is covered by ice, where in-situ measurements are difficult. Some experimental airborne radar and ground-based radar data have revealed very limited land topography beneath heavy ice sheet. To estimate the land topography for the full coverage of Antarctica, we combine GRACE data that indicate the mass distribution, with data of ICESat laser altimetry that provide high-resolution mapping of ice topography. Our approach is actually based on some geological constraints: assuming uniform densities of the land and ice considering the Airy-type isostasy. In the beginning we construct an initial model for the ice thickness and land topography based on the BEDMAP ice thickness and ICESat data. Thereafter we forward compute the model’s gravity field and compare with the GRACE observed data. Our initial model undergoes the adjustments to improve the fit between modeled results and the observed data. Final examination is done by comparing our results with previous but sparse observations of ice thickness to reconfirm the reliability of our results. As the gravitational inversion problem is non-unique, our estimating result is just one of all possibilities constrained by available data in optimal way.

Identifying water mass depletion in northern Iraq observed by GRACE

NARCIS (Netherlands)

Mulder, G.; Olsthoorn, T.N.; Al-manmi, D.A.M.A.; Schrama, E.J.O.; Smidt, E.H.

2015-01-01

Observations acquired by Gravity Recovery And Climate Experiment (GRACE) mission indicate a mass loss of 146 ± 6 mm equivalent water height (EWH) in northern Iraq between 2007 and 2009. These data are used as an independent validation of lake mass variations and a rainfall-runoff model, which is

Greenland Ice Sheet seasonal and spatial mass variability from model simulations and GRACE (2003-2012)

Science.gov (United States)

Alexander, Patrick M.; Tedesco, Marco; Schlegel, Nicole-Jeanne; Luthcke, Scott B.; Fettweis, Xavier; Larour, Eric

2016-06-01

Improving the ability of regional climate models (RCMs) and ice sheet models (ISMs) to simulate spatiotemporal variations in the mass of the Greenland Ice Sheet (GrIS) is crucial for prediction of future sea level rise. While several studies have examined recent trends in GrIS mass loss, studies focusing on mass variations at sub-annual and sub-basin-wide scales are still lacking. At these scales, processes responsible for mass change are less well understood and modeled, and could potentially play an important role in future GrIS mass change. Here, we examine spatiotemporal variations in mass over the GrIS derived from the Gravity Recovery and Climate Experiment (GRACE) satellites for the January 2003-December 2012 period using a "mascon" approach, with a nominal spatial resolution of 100 km, and a temporal resolution of 10 days. We compare GRACE-estimated mass variations against those simulated by the Modèle Atmosphérique Régionale (MAR) RCM and the Ice Sheet System Model (ISSM). In order to properly compare spatial and temporal variations in GrIS mass from GRACE with model outputs, we find it necessary to spatially and temporally filter model results to reproduce leakage of mass inherent in the GRACE solution. Both modeled and satellite-derived results point to a decline (of -178.9 ± 4.4 and -239.4 ± 7.7 Gt yr-1 respectively) in GrIS mass over the period examined, but the models appear to underestimate the rate of mass loss, especially in areas below 2000 m in elevation, where the majority of recent GrIS mass loss is occurring. On an ice-sheet-wide scale, the timing of the modeled seasonal cycle of cumulative mass (driven by summer mass loss) agrees with the GRACE-derived seasonal cycle, within limits of uncertainty from the GRACE solution. However, on sub-ice-sheet-wide scales, some areas exhibit significant differences in the timing of peaks in the annual cycle of mass change. At these scales, model biases, or processes not accounted for by models related

Mass-induced [|#8#|]Sea Level Variations in the Red Sea from Satellite Altimetry and GRACE

Science.gov (United States)

Feng, W.; Lemoine, J.; Zhong, M.; Hsu, H.

2011-12-01

We have analyzed mass-induced sea level variations (SLVs) in the Red Sea from steric-corrected altimetry and GRACE between January 2003 and December 2010. The steric component of SLVs in the Red Sea calculated from climatological temperature and salinity data is relatively small and anti-phase with the mass-induced SLV. The total SLV in the Red Sea is mainly driven by the mass-induced SLV, which increases in winter when the Red Sea gains the water mass from the Gulf of Aden and vice versa in summer. Spatial and temporal patterns of mass-induced SLVs in the Red Sea from steric-corrected altimetry agree very well with GRACE observations. Both of two independent observations show high annual amplitude in the central Red Sea (>20cm). Total mass-induced SLVs in the Red Sea from two independent observations have similar annual amplitude and phase. One main purpose of our work is to see whether GRGS's ten-day GRACE results can observe intra-seasonal mass change in the Red Sea. The wavelet coherence analysis indicates that GRGS's results show the high correlation with the steric-corrected SLVs on intra-seasonal time scale. The agreement is excellent for all the time-span until 1/3 year period and is patchy between 1/3 and 1/16 year period. Furthermore, water flux estimates from current-meter arrays and moorings show mass gain in winter and mass loss in summer, which is also consistent with altimetry and GRACE.

GRACE Hydrological estimates for small basins: Evaluating processing approaches on the High Plains Aquifer, USA

Science.gov (United States)

Longuevergne, Laurent; Scanlon, Bridget R.; Wilson, Clark R.

2010-11-01

The Gravity Recovery and Climate Experiment (GRACE) satellites provide observations of water storage variation at regional scales. However, when focusing on a region of interest, limited spatial resolution and noise contamination can cause estimation bias and spatial leakage, problems that are exacerbated as the region of interest approaches the GRACE resolution limit of a few hundred km. Reliable estimates of water storage variations in small basins require compromises between competing needs for noise suppression and spatial resolution. The objective of this study was to quantitatively investigate processing methods and their impacts on bias, leakage, GRACE noise reduction, and estimated total error, allowing solution of the trade-offs. Among the methods tested is a recently developed concentration algorithm called spatiospectral localization, which optimizes the basin shape description, taking into account limited spatial resolution. This method is particularly suited to retrieval of basin-scale water storage variations and is effective for small basins. To increase confidence in derived methods, water storage variations were calculated for both CSR (Center for Space Research) and GRGS (Groupe de Recherche de Géodésie Spatiale) GRACE products, which employ different processing strategies. The processing techniques were tested on the intensively monitored High Plains Aquifer (450,000 km2 area), where application of the appropriate optimal processing method allowed retrieval of water storage variations over a portion of the aquifer as small as ˜200,000 km2.

Development and Release of a GRACE-FO "Grand Simulation" Data Set by JPL

Science.gov (United States)

Fahnestock, E.; Yuan, D. N.; Wiese, D. N.; McCullough, C. M.; Harvey, N.; Sakumura, C.; Paik, M.; Bertiger, W. I.; Wen, H. Y.; Kruizinga, G. L. H.

2017-12-01

The GRACE-FO mission, to be launched early in 2018, will require several stages of data processing to be performed within its Science Data System (SDS). In an effort to demonstrate effective implementation and inter-operation of this level 1, 2, and 3 data processing, and to verify its combined ability to recover a truth Earth gravity field to within top-level requirements, the SDS team has performed a system test which it has termed the "Grand Simulation". This process starts with iteration to converge on a mutually consistent integrated truth orbit, non-gravitational acceleration time history, and spacecraft attitude time history, generated with the truth models for all elements of the integrated system (geopotential, both GRACE-FO spacecraft, constellation of GPS spacecraft, etc.). Level 1A data products are generated and then the GPS time to onboard receiver time clock error is introduced into those products according to a realistic truth clock offset model. The various data products are noised according to current best estimate noise models, and then some are used within a precision orbit determination and clock offset estimation/recovery process. Processing from level 1A to level 1B data products uses the recovered clock offset to correct back to GPS time, and performs gap-filling, compression, etc. This exercises nearly all software pathways intended for processing actual GRACE-FO science data. Finally, a monthly gravity field is recovered and compared against the truth background field. In this talk we briefly summarize the resulting performance vs. requirements, and lessons learned in the system test process. Finally, we provide information for use of the level 1B data set by the general community for gravity solution studies and software trials in anticipation of operational GRACE-FO data. ©2016 California Institute of Technology. Government sponsorship acknowledged.

The design, validation, and performance of Grace

Directory of Open Access Journals (Sweden)

Ru Zhu

2016-05-01

Full Text Available The design, validation and performance of Grace, a GPU-accelerated micromagnetic simulation software, are presented. The software adopts C+ + Accelerated Massive Parallelism (C+ + AMP so that it runs on GPUs from various hardware vendors including NVidia, AMD and Intel. At large simulation scales, up to two orders of magnitude of speedup factor is observed, compared to CPU-based micromagnetic simulation software OOMMF. The software can run on high-end professional GPUs as well as budget personal laptops, and is free to download.

[Prediction value of deceleration capacity of rate and GRACE risk score on major adverse cardiac events in patients with acute myocardial infarction].

Science.gov (United States)

Gao, L; Chen, Y D; Shi, Y J; Xue, H; Wang, J L

2016-07-24

To investigate the prediction value of deceleration capacity of rate (DC) and GRACE risk score for cardiovascular events in AMI patients. Consecutive AMI patients with sinus rhythm hospitalized in our department during August 2012 to August 2013 were included in this prospective study. 24-hour ECG Holter monitoring was performed within 1 week, and the DC value was analyzed, GRACE risk score was acquired with the application of GRACE risk score calculator. Patients were followed up for more than 1 year and major adverse cardiac events (MACE) were obtained. Analysised the Kaplan Meier survival according to DC and GRACE score risk stratification respectively. A total of 157 patients were enrolled in the study (average age: (58.9±12.7)years old). The average follow-up was (20.54±2.85) months. Mortality during follow-up was significantly higher in patients with DC>2.5 compared to patients with DC≤2.5 (Prisk stratification was 0.898 (95%CI 0.840-0.940, Prisk stratification was 0.786 (95%CI 0.714-0.847, Prisk stratification was 0.708 (95%CI 0.652-0.769, Prisk patients than those with intermediate and low risk patients according to DC risk stratification in intermediate and low risk patients by GRACE risk stratification (Prisk stratification is superior to GRACE risk score on outcome assessment in this AMI patient cohort.

Estimation of regional mass anomalies from Gravity Recovery and Climate Experiment (GRACE) over Himalayan region

Science.gov (United States)

Agrawal, R.; Singh, S. K.; Rajawat, A. S.; Ajai

2014-11-01

Time-variable gravity changes are caused by a combination of postglacial rebound, redistribution of water and snow/ice on land and as well as in the ocean. The Gravity Recovery and Climate Experiment (GRACE) satellite mission, launched in 2002, provides monthly average of the spherical harmonic co-efficient. These spherical harmonic co-efficient describe earth's gravity field with a resolution of few hundred kilometers. Time-variability of gravity field represents the change in mass over regional level with accuracies in cm in terms of Water Equivalent Height (WEH). The WEH reflects the changes in the integrated vertically store water including snow cover, surface water, ground water and soil moisture at regional scale. GRACE data are also sensitive towards interior strain variation, surface uplift and surface subsidence cover over a large area. GRACE data was extracted over the three major Indian River basins, Indus, Ganga and Brahmaputra, in the Himalayas which are perennial source of fresh water throughout the year in Northern Indian Plain. Time series analysis of the GRACE data was carried out from 2003-2012 over the study area. Trends and amplitudes of the regional mass anomalies in the region were estimated using level 3 GRACE data product with a spatial resolution at 10 by 10 grid provided by Center for Space Research (CSR), University of Texas at Austin. Indus basin has shown a subtle decreasing trend from 2003-2012 however it was observed to be statistically insignificant at 95 % confidence level. Ganga and Brahmaputra basins have shown a clear decreasing trend in WEH which was also observed to be statistically significant. The trend analysis over Ganga and Brahamputra basins have shown an average annual change of -1.28 cm and -1.06 cm in terms of WEH whereas Indus basin has shown a slight annual change of -0.07 cm. This analysis will be helpful to understand the loss of mass in terms of WEH over Indian Himalayas and will be crucial for hydrological and

Gravity Recovery and Climate Experiment (GRACE) detection of water storage changes in the Three Gorges Reservoir of China and comparison with in situ measurements

Science.gov (United States)

Wang, Xianwei; de Linage, Caroline; Famiglietti, James; Zender, Charles S.

2011-12-01

Water impoundment in the Three Gorges Reservoir (TGR) of China caused a large mass redistribution from the oceans to a concentrated land area in a short time period. We show that this mass shift is captured by the Gravity Recovery and Climate Experiment (GRACE) unconstrained global solutions at a 400 km spatial resolution after removing correlated errors. The WaterGAP Global Hydrology Model (WGHM) is selected to isolate the TGR contribution from regional water storage changes. For the first time, this study compares the GRACE (minus WGHM) estimated TGR volume changes with in situ measurements from April 2002 to May 2010 at a monthly time scale. During the 8 year study period, GRACE-WGHM estimated TGR volume changes show an increasing trend consistent with the TGR in situ measurements and lead to similar estimates of impounded water volume. GRACE-WGHM estimated total volume increase agrees to within 14% (3.2 km3) of the in situ measurements. This indicates that GRACE can retrieve the true amplitudes of large surface water storage changes in a concentrated area that is much smaller than the spatial resolution of its global harmonic solutions. The GRACE-WGHM estimated TGR monthly volume changes explain 76% (r2 = 0.76) of in situ measurement monthly variability and have an uncertainty of 4.62 km3. Our results also indicate reservoir leakage and groundwater recharge due to TGR filling and contamination from neighboring lakes are nonnegligible in the GRACE total water storage changes. Moreover, GRACE observations could provide a relatively accurate estimate of global water volume withheld by newly constructed large reservoirs and their impacts on global sea level rise since 2002.

GRACE Gravity Satellite Observations of Terrestrial Water Storage Changes for Drought Characterization in the Arid Land of Northwestern China

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Yanping Cao

2015-01-01

Full Text Available Drought is a complex natural hazard which can have negative effects on agriculture, economy, and human life. In this paper, the primary goal is to explore the application of the Gravity Recovery and Climate Experiment (GRACE gravity satellite data for the quantitative investigation of the recent drought dynamic over the arid land of northwestern China, a region with scarce hydrological and meteorological observation datasets. The spatiotemporal characteristics of terrestrial water storage changes (TWSC were first evaluated based on the GRACE satellite data, and then validated against hydrological model simulations and precipitation data. A drought index, the total storage deficit index (TSDI, was derived on the basis of GRACE-recovered TWSC. The spatiotemporal distributions of drought events from 2003 to 2012 in the study region were obtained using the GRACE-derived TSDI. Results derived from TSDI time series indicated that, apart from four short-term (three months drought events, the study region experienced a severe long-term drought from May 2008 to December 2009. As shown in the spatial distribution of TSDI-derived drought conditions, this long-term drought mainly concentrated in the northwestern area of the entire region, where the terrestrial water storage was in heavy deficit. These drought characteristics, which were detected by TSDI, were consistent with local news reports and other researchers’ results. Furthermore, a comparison between TSDI and Standardized Precipitation Index (SPI implied that GRACE TSDI was a more reliable integrated drought indicator (monitoring agricultural and hydrological drought in terms of considering total terrestrial water storages for large regions. The GRACE-derived TSDI can therefore be used to characterize and monitor large-scale droughts in the arid regions, being of special value for areas with scarce observations.

Reconciling ocean mass content change based on direct and inverse approaches by utilizing data from GRACE, altimetry and Swarm

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Rietbroek, R.; Uebbing, B.; Lück, C.; Kusche, J.

2017-12-01

Ocean mass content (OMC) change due to the melting of the ice-sheets in Greenland and Antarctica, melting of glaciers and changes in terrestrial hydrology is a major contributor to present-day sea level rise. Since 2002, the GRACE satellite mission serves as a valuable tool for directly measuring the variations in OMC. As GRACE has almost reached the end of its lifetime, efforts are being made to utilize the Swarm mission for the recovery of low degree time-variable gravity fields to bridge a possible gap until the GRACE-FO mission and to fill up periods where GRACE data was not existent. To this end we compute Swarm monthly normal equations and spherical harmonics that are found competitive to other solutions. In addition to directly measuring the OMC, combination of GRACE gravity data with altimetry data in a global inversion approach allows to separate the total sea level change into individual mass-driven and steric contributions. However, published estimates of OMC from the direct and inverse methods differ not only depending on the time window, but also are influenced by numerous post-processing choices. Here, we will look into sources of such differences between direct and inverse approaches and evaluate the capabilities of Swarm to derive OMC. Deriving time series of OMC requires several processing steps; choosing a GRACE (and altimetry) product, data coverage, masks and filters to be applied in either spatial or spectral domain, corrections related to spatial leakage, GIA and geocenter motion. In this study, we compare and quantify the effects of the different processing choices of the direct and inverse methods. Our preliminary results point to the GIA correction as the major source of difference between the two approaches.

Can mountain glacier melting explains the GRACE-observed mass loss in the southeast Tibetan Plateau: From a climate perspective?

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Song, Chunqiao; Ke, Linghong; Huang, Bo; Richards, Keith S.

2015-01-01

The southeast Tibetan Plateau (SETP) includes the majority of monsoonal temperate glaciers in High Mountain Asia (HMA), which is an important source of water for the upper reaches of several large Asian river systems. Climatic change and variability has substantial impacts on cryosphere and hydrological processes in the SETP. The Gravity Recovery and Climate Experiment (GRACE) gravimetry observations between 2003 and 2009 suggest that there was an average mass loss rate of - 5.99 ± 2.78 Gigatonnes (Gt)/yr in this region. Meanwhile, the hydrological data by model calculations from the GLDAS/Noah and CPC are used to estimate terrestrial water storage (TWS) changes with a slight negative trend of about - 0.3 Gt/yr. The recent studies (Kääb et al., 2012; Gardner et al., 2013) reported the thinning rates of mountain glaciers in HMA based on the satellite laser altimetry, and an approximate estimation of the glacier mass budget in the SETP was 4.69 ± 2.03 Gt/yr during 2003-2009. This estimate accounted for a large proportion ( 78.3%) of the difference between the GRACE TWS and model-calculated TWS changes. To better understand the cause of sharp mass loss existing in the SETP, the correlations between key climatic variables (precipitation and temperature) and the GRACE TWS changes are examined at different timescales between 2003 and 2011. The results show that precipitation is the leading factors of abrupt, seasonal and multi-year undulating signals of GRACE TWS anomaly time series, but with weak correlations with the inter-annual trend and annual mass budget of GRACE TWS. In contrast, the annual mean temperature is tightly associated with the annual net mass budget (r = 0.81, p < 0.01), which indirectly suggests that the GRACE-observed mass loss in the SETP may be highly related to glacial processes.

Mass loss of Greenland from GRACE, IceSat and CryoSat

DEFF Research Database (Denmark)

Forsberg, René; Sørensen, Louise Sandberg; Fredenslund Levinsen, Joanna

2013-01-01

CryoSat data over the Greenland Ice Sheet are used to continue elevation height change data over the Greenland ice sheet, following a decade of detailed monitoring of ice sheet changes with GRACE and IceSat. The combination and validation of the different data for measuring changes is quantified...... by using available airborne lidar data from IceBridge and CryoVEx. There is a special challenge of using CryoSat as fill-in between EnviSat and Sentinel-3 for the longterm measurements of surface elevation changes, a key essential climate variable in the ESA Climate Change Initiative. Another challenge...... is the joint utilization of both altimetry and gravity field change measurements for consistent estimates of regional change patterns. In the paper we analyze GRACE, IceSat and CryoSat data since 2003, and present consistent estimates of overall mass changes with average values around -220 GT/year, showing...

Global sea level variations from altimetry, GRACE and Argo data over 2005–2014

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Wei Feng

2015-07-01

Full Text Available Total sea level variations (SLVs are caused by two major components: steric variations due to thermal expansion of seawater, and mass-induced variations due to mass exchange between ocean and land. In this study, the global SLV and its steric and mass components were estimated by satellite altimetry, Argo float data and the Gravity Recovery and Climate Experiment (GRACE data over 2005–2014. Space gravimetry observations from GRACE suggested that two-thirds of the global mean sea level rise rate observed by altimetry (i.e., 3.1 ± 0.3 mm/a from 2005 to 2014 could be explained by an increase in ocean mass. Furthermore, the global mean sea level was observed to drop significantly during the 2010/2011 La Niña event, which may be attributed to the decline of ocean mass and steric SLV. Since early 2011, the global mean sea level began to rise rapidly, which was attributed to an increase in ocean mass. The findings in this study suggested that the global mean sea-level budget was closed from 2005 to 2014 based on altimetry, GRACE, and Argo data.

Coseismic and post-seismic signatures of the Sumatra 2004 December and 2005 March earthquakes in GRACE satellite gravity

Science.gov (United States)

Panet, I.; Mikhailov, V.; Diament, M.; Pollitz, F.; King, G.; de Viron, O.; Holschneider, M.; Biancale, R.; Lemoine, J.-M.

2007-01-01

The GRACE satellite mission has been measuring the Earth's gravity field and its temporal variations since 2002 April. Although these variations are mainly due to mass transfer within the geofluid envelops, they also result from mass displacements associated with phenomena including glacial isostatic adjustment and earthquakes. However, these last contributions are difficult to isolate because of the presence of noise and of geofluid signals, and because of GRACE's coarse spatial resolution (>400 km half-wavelength). In this paper, we show that a wavelet analysis on the sphere helps to retrieve earthquake signatures from GRACE geoid products. Using a wavelet analysis of GRACE geoids products, we show that the geoid variations caused by the 2004 December (Mw = 9.2) and 2005 March (Mw = 8.7) Sumatra earthquakes can be detected. At GRACE resolution, the 2004 December earthquake produced a strong coseismic decrease of the gravity field in the Andaman Sea, followed by relaxation in the area affected by both the Andaman 2004 and the Nias 2005 earthquakes. We find two characteristic timescales for the relaxation, with a fast variation occurring in the vicinity of the Central Andaman ridge. We discuss our coseismic observations in terms of density changes of crustal and upper-mantle rocks, and of the vertical displacements in the Andaman Sea. We interpret the post-seismic signal in terms of the viscoelastic response of the Earth's mantle. The transient component of the relaxation may indicate the presence of hot, viscous material beneath the active Central Andaman Basin. ?? 2007 The Authors Journal compilation ?? 2007 RAS.

An Economy of Grace

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Victor Tan Chen

2017-03-01

Full Text Available This essay is adapted from a plenary talk the author gave at the “Growing Apart: The Implications of Economic Inequality” interdisciplinary conference at Boston College on 9 April 2016, as well as portions of his book Cut Loose: Jobless and Hopeless in an Unfair Economy, a sociological ethnography based on interviews and observations of unemployed autoworkers in Detroit, Michigan, and Windsor, Canada, during and after the Great Recession. The essay discusses four themes from this research. First, it provides a sociological understanding of how long-term unemployment and economic inequality are experienced by today’s less advantaged workers. Second, it illustrates how social policy can improve their circumstances. Third, it examines the limits of policy, and how dealing with inequality also requires changing the broader culture. Fourth, it makes the case for one possible approach to bring about that cultural change: a morality of grace.

GRACE gravity model: assssment in terms of deep ocean currents from hydrography and from the ECCO ocean model

Science.gov (United States)

Zlotnicki, V.; Stammer, D.; Fukumori, I.

2003-01-01

Here we assess the new generation of gravity models, derived from GRACE data. The differences between a global geoid model (one from GRACE data and one the well-known EGM-96), minus a Mean Sea Surface derived from over a decade of altimetric data are compared to hydrographic data from the Levitus compilation and to the ECCO numerical ocean model, which assimilates altimetry and other data.

Status of GRACE system - automatic computation of cross sections

International Nuclear Information System (INIS)

Fujimoto, J.; Ishikawa, T.; Kawabata, S.; Kurihara, Y.; Shimizu, Y.; Kato, K.; Nakazawa, N.; Kaneko, T.; Tanaka, H.

1995-01-01

Automated system is an essential tool for high-energy physics and GRACE system for tree processes makes it possible to calculate cross sections for complicated processes exactly. To check the output of the automatic system we make comparison between Hooft-t-Feynman gauge and unitary gauge, the exchange of external particles, and we check the independence of UV divergence parameter and that of IR divergence parameter

GIA Model Statistics for GRACE Hydrology, Cryosphere, and Ocean Science

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Caron, L.; Ivins, E. R.; Larour, E.; Adhikari, S.; Nilsson, J.; Blewitt, G.

2018-03-01

We provide a new analysis of glacial isostatic adjustment (GIA) with the goal of assembling the model uncertainty statistics required for rigorously extracting trends in surface mass from the Gravity Recovery and Climate Experiment (GRACE) mission. Such statistics are essential for deciphering sea level, ocean mass, and hydrological changes because the latter signals can be relatively small (≤2 mm/yr water height equivalent) over very large regions, such as major ocean basins and watersheds. With abundant new >7 year continuous measurements of vertical land motion (VLM) reported by Global Positioning System stations on bedrock and new relative sea level records, our new statistical evaluation of GIA uncertainties incorporates Bayesian methodologies. A unique aspect of the method is that both the ice history and 1-D Earth structure vary through a total of 128,000 forward models. We find that best fit models poorly capture the statistical inferences needed to correctly invert for lower mantle viscosity and that GIA uncertainty exceeds the uncertainty ascribed to trends from 14 years of GRACE data in polar regions.

Intensified water storage loss by biomass burning in Kalimantan: Detection by GRACE

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Han, Jiancheng; Tangdamrongsub, Natthachet; Hwang, Cheinway; Abidin, Hasanuddin Z.

2017-03-01

Biomass burning is the principal tool for land clearing and a primary driver of land use change in Kalimantan (the Indonesian part of Borneo island). Biomass burning here has consumed millions of hectares of peatland and swamp forests. It also degrades air quality in Southeast Asia, perturbs the global carbon cycle, threatens ecosystem health and biodiversity, and potentially affects the global water cycle. Here we present the optimal estimate of water storage changes over Kalimantan from NASA's Gravity Recovery and Climate Experiment (GRACE). Over August 2002 to December 2014, our result shows a north-south dipole pattern in the long-term changes in terrestrial water storage (TWS) and groundwater storage (GWS). Both TWS and GWS increase in the northern part of Kalimantan, while they decrease in the southern part where fire events are the most severe. The loss rates in TWS and GWS in the southern part are 0.56 ± 0.11 cm yr-1 and 0.55 ± 0.10 cm yr-1, respectively. We use GRACE estimates, burned area, carbon emissions, and hydroclimatic data to study the relationship between biomass burning and water storage losses. The analysis shows that extensive biomass burning results in excessive evapotranspiration, which then increases long-term water storage losses in the fire-prone region of Kalimantan. Our results show the potentials of GRACE and its follow-on missions in assisting water storage and fire managements in a region with extensive biomass burning such as Kalimantan.

Improving estimates of water resources in a semi-arid region by assimilating GRACE data into the PCR-GLOBWB hydrological model

Science.gov (United States)

Tangdamrongsub, Natthachet; Steele-Dunne, Susan C.; Gunter, Brian C.; Ditmar, Pavel G.; Sutanudjaja, Edwin H.; Sun, Yu; Xia, Ting; Wang, Zhongjing

2017-04-01

An accurate estimation of water resources dynamics is crucial for proper management of both agriculture and the local ecology, particularly in semi-arid regions. Imperfections in model physics, uncertainties in model land parameters and meteorological data, as well as the human impact on land changes often limit the accuracy of hydrological models in estimating water storages. To mitigate this problem, this study investigated the assimilation of terrestrial water storage variation (TWSV) estimates derived from the Gravity Recovery And Climate Experiment (GRACE) data using an ensemble Kalman filter (EnKF) approach. The region considered was the Hexi Corridor in northern China. The hydrological model used for the analysis was PCR-GLOBWB, driven by satellite-based forcing data from April 2002 to December 2010. The impact of the GRACE data assimilation (DA) scheme was evaluated in terms of the TWSV, as well as the variation of individual hydrological storage estimates. The capability of GRACE DA to adjust the storage level was apparent not only for the entire TWSV but also for the groundwater component. In this study, spatially correlated errors in GRACE data were taken into account, utilizing the full error variance-covariance matrices provided as a part of the GRACE data product. The benefits of this approach were demonstrated by comparing the EnKF results obtained with and without taking into account error correlations. The results were validated against in situ groundwater data from five well sites. On average, the experiments showed that GRACE DA improved the accuracy of groundwater storage estimates by as much as 25 %. The inclusion of error correlations provided an equal or greater improvement in the estimates. In contrast, a validation against in situ streamflow data from two river gauges showed no significant benefits of GRACE DA. This is likely due to the limited spatial and temporal resolution of GRACE observations. Finally, results of the GRACE DA study

Improved predictive value of GRACE risk score combined with platelet reactivity for 1-year cardiovascular risk in patients with acute coronary syndrome who underwent coronary stent implantation.

Science.gov (United States)

Li, Shan; Liu, Hongbin; Liu, Jianfeng; Wang, Haijun

2016-11-01

Both high platelet reactivity (HPR) and Global Registry of Acute Coronary Events (GRACE) risk score have moderate predictive value for major adverse cardiovascular disease (CVD) events in patients with acute coronary syndrome (ACS) who underwent percutaneous coronary intervention (PCI), whereas the prognostic significance of GRACE risk score combined with platelet function testing remains unclear. A total of 596 patients with non-ST elevation ACS who underwent PCI were enrolled. The P2Y 12 reaction unit (PRU) value was measured by VerifyNow P2Y 12 assay and GRACE score was calculated by GRACE risk 2.0 calculator. Patients were stratified by a pre-specified cutoff value of PRU 230 and GRACE score 140 to assess 1-year risk of cardiovascular death, non-fatal myocardial infarction (MI), and stent thrombosis. Seventy-two (12.1%) patients developed CVD events during 1-year follow-up. Patients with CVD events had a higher PRU value (244.6 ± 50.9 vs. 203.7 ± 52.0, p risk independently. Compared to patients with normal platelet reactivity (NPR) and GRACE score risk (HR: 5.048; 95% CI: 2.268-11.237; p risk score yielded superior risk predictive capacity beyond GRACE score alone, which is shown by improved c-statistic value (0.871, p = 0.002) as well as net reclassification improvement (NRI 0.263, p risk of adverse CVD events. The combination of platelet function testing and GRACE score predicted 1-year CVD risk better.

Seasonal Hydrological Loading in Southern Tibet Detected by Joint Analysis of GPS and GRACE.

Science.gov (United States)

Zou, Rong; Wang, Qi; Freymueller, Jeffrey T; Poutanen, Markku; Cao, Xuelian; Zhang, Caihong; Yang, Shaomin; He, Ping

2015-12-04

In southern Tibet, ongoing vertical and horizontal motions due to the collision between India and Eurasia are monitored by large numbers of global positioning system (GPS) continuous and campaign sites installed in the past decade. Displacements measured by GPS usually include tectonic deformation as well as non-tectonic, time-dependent signals. To estimate the regional long-term tectonic deformation using GPS more precisely, seasonal elastic deformation signals associated with surface loading must be removed from the observations. In this study, we focus on seasonal variation in vertical and horizontal motions of southern Tibet by performing a joint analysis of GRACE (Gravity Recovery and Climate Experiment) and GPS data, not only using continuous sites but also GPS campaign-mode sites. We found that the GPS-observed and GRACE-modeled seasonal oscillations are in good agreements, and a seasonal displacement model demonstrates that the main reason for seasonal variations in southern Tibet is from the summer monsoon and its precipitation. The biggest loading appears from July to August in the summer season. Vertical deformations observed by GPS and modeled by GRACE are two to three times larger than horizontal oscillations, and the north components demonstrate larger amplitudes than the east components. We corrected the GPS position time series using the GRACE-modeled seasonal variations, which gives significant reductions in the misfit and weighted root-mean-squares (WRMS). Misfit (χ2 divided by degree of freedom) reductions for campaign sites range between 20% and 56% for the vertical component, and are much smaller for the horizontal components. Moreover, time series of continuous GPS (cGPS) sites near the 2015 Nepal earthquakes must be corrected using appropriate models of seasonal loading for analyzing postseismic deformation to avoid biasing estimates of the postseismic relaxation.

Regionally Optimized GRACE Processing and Inter-comparison on the Antarctic Ice Sheet

Science.gov (United States)

Mohajerani, Y.; Velicogna, I.; Sutterley, T. C.; Rignot, E. J.

2017-12-01

The Antarctic ice sheet is losing mass at an accelerating rate, with a sea level contribution that changed from 0.08mm/yr from 1992 to 2001 to 0.4mm/yr from 2002 to 2011. While most of this contribution comes from West Antarctica, Totten Glacier has the largest discharge of ice in East Antarctica, with a sea level rise potential of 3.9 m. Furthermore, the drainage basin of Totten Glacier, along the neighboring Moscow University Glacier are below sea level, extending hundreds of kilometers inland. Therefore, obtaining regional estimates of both western and eastern Antarctic basins are of critical importance. The GRACE (Gravity Recovery and Climate Experiment) satellite has been providing mass balance time-series from geoid changes since 2002. Several mascon and harmonic GRACE solutions are available from different processing centers. Here, we evaluate the various solutions across the ice sheet and a new set of regionally optimized mascons to study the mass balance of Totten and Moscow University glaciers. We obtain a trend of -16.5±4.1Gt/yr with an acceleration of -2.0±1.8Gt/yr2 for the two glaciers for the period April 2002 to December 2016 using the Ivins et al (2013) GIA model (errors include leakage, GIA, and regression errors). We compare the results with the Mass Budget Method that combines ice discharge (D) and surface mass balance (SMB) from two models: 1) RACMO2.3, and 2) MAR3.6.4. MBM/RACMO2.3 shows the best agreement with the GRACE estimates. Within the common period from April 2002 to December 2015, the MBM/RACMO2.3 and MAR3.6.4 results are -15.6±1.8Gt/yr and -6.7±1.5Gt/yr respectively, while the GRACE time-series has a trend of -14.8±2.7 Gt/yr. We extend the study to the Getz Ice Shelf, the third largest ice shelf in West Antarctica after Ronne and Ross West ice shelves. We compare our gravity-derived mass estimates, the mass budget estimates, and the volume changes from altimetry data to compare the estimates and obtain a multi-sensor assessment

Assessing sequential data assimilation techniques for integrating GRACE data into a hydrological model

KAUST Repository

Khaki, M.; Hoteit, Ibrahim; Kuhn, M.; Awange, J.; Forootan, E.; van Dijk, A.; Schumacher, M.; Pattiaratchi, C.

2017-01-01

The time-variable terrestrial water storage (TWS) products from the Gravity Recovery And Climate Experiment (GRACE) have been increasingly used in recent years to improve the simulation of hydrological models by applying data assimilation techniques

Does simplicity compromise accuracy in ACS risk prediction? A retrospective analysis of the TIMI and GRACE risk scores.

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Krishna G Aragam

Full Text Available BACKGROUND: The Thrombolysis in Myocardial Infarction (TIMI risk scores for Unstable Angina/Non-ST-elevation myocardial infarction (UA/NSTEMI and ST-elevation myocardial infarction (STEMI and the Global Registry of Acute Coronary Events (GRACE risk scores for in-hospital and 6-month mortality are established tools for assessing risk in Acute Coronary Syndrome (ACS patients. The objective of our study was to compare the discriminative abilities of the TIMI and GRACE risk scores in a broad-spectrum, unselected ACS population and to assess the relative contributions of model simplicity and model composition to any observed differences between the two scoring systems. METHODOLOGY/PRINCIPAL FINDINGS: ACS patients admitted to the University of Michigan between 1999 and 2005 were divided into UA/NSTEMI (n = 2753 and STEMI (n = 698 subpopulations. The predictive abilities of the TIMI and GRACE scores for in-hospital and 6-month mortality were assessed by calibration and discrimination. There were 137 in-hospital deaths (4%, and among the survivors, 234 (7.4% died by 6 months post-discharge. In the UA/NSTEMI population, the GRACE risk scores demonstrated better discrimination than the TIMI UA/NSTEMI score for in-hospital (C = 0.85, 95% CI: 0.81-0.89, versus 0.54, 95% CI: 0.48-0.60; p<0.01 and 6-month (C = 0.79, 95% CI: 0.76-0.83, versus 0.56, 95% CI: 0.52-0.60; p<0.01 mortality. Among STEMI patients, the GRACE and TIMI STEMI scores demonstrated comparably excellent discrimination for in-hospital (C = 0.84, 95% CI: 0.78-0.90 versus 0.83, 95% CI: 0.78-0.89; p = 0.83 and 6-month (C = 0.72, 95% CI: 0.63-0.81, versus 0.71, 95% CI: 0.64-0.79; p = 0.79 mortality. An analysis of refitted multivariate models demonstrated a marked improvement in the discriminative power of the TIMI UA/NSTEMI model with the incorporation of heart failure and hemodynamic variables. Study limitations included unaccounted for confounders inherent to observational, single institution

Evaluating water storage variations in the MENA region using GRACE satellite data

KAUST Repository

Lopez, Oliver

2013-12-01

Terrestrial water storage (TWS) variations over large river basins can be derived from temporal gravity field variations observed by the Gravity Recovery and Climate Experiment (GRACE) satellites. These signals are useful for determining accurate estimates of water storage and fluxes over areas covering a minimum of 150,000 km2 (length scales of a few hundred kilometers) and thus prove to be a valuable tool for regional water resources management, particularly for areas with a lack of in-situ data availability or inconsistent monitoring, such as the Middle East and North Africa (MENA) region. This already stressed arid region is particularly vulnerable to climate change and overdraft of its non-renewable freshwater sources, and thus direction in managing its resources is a valuable aid. An inter-comparison of different GRACE-derived TWS products was done in order to provide a quantitative assessment on their uncertainty and their utility for diagnosing spatio-temporal variability in water storage over the MENA region. Different processing approaches for the inter-satellite tracking data from the GRACE mission have resulted in the development of TWS products, with resolutions in time from 10 days to 1 month and in space from 0.5 to 1 degree global gridded data, while some of them use input from land surface models in order to restore the original signal amplitudes. These processing differences and the difficulties in recovering the mass change signals over arid regions will be addressed. Output from the different products will be evaluated and compared over basins inside the MENA region, and compared to output from land surface models.

Evaluating Water Storage Variations in the MENA region using GRACE Satellite Data

Science.gov (United States)

Lopez, O.; Houborg, R.; McCabe, M. F.

2013-12-01

Terrestrial water storage (TWS) variations over large river basins can be derived from temporal gravity field variations observed by the Gravity Recovery and Climate Experiment (GRACE) satellites. These signals are useful for determining accurate estimates of water storage and fluxes over areas covering a minimum of 150,000 km2 (length scales of a few hundred kilometers) and thus prove to be a valuable tool for regional water resources management, particularly for areas with a lack of in-situ data availability or inconsistent monitoring, such as the Middle East and North Africa (MENA) region. This already stressed arid region is particularly vulnerable to climate change and overdraft of its non-renewable freshwater sources, and thus direction in managing its resources is a valuable aid. An inter-comparison of different GRACE-derived TWS products was done in order to provide a quantitative assessment on their uncertainty and their utility for diagnosing spatio-temporal variability in water storage over the MENA region. Different processing approaches for the inter-satellite tracking data from the GRACE mission have resulted in the development of TWS products, with resolutions in time from 10 days to 1 month and in space from 0.5 to 1 degree global gridded data, while some of them use input from land surface models in order to restore the original signal amplitudes. These processing differences and the difficulties in recovering the mass change signals over arid regions will be addressed. Output from the different products will be evaluated and compared over basins inside the MENA region, and compared to output from land surface models.

Seasonal changes in the European gravity field from GRACE: A comparison with superconducting gravimeters and hydrology model predictions

Science.gov (United States)

Hinderer, Jacques; Andersen, Ole; Lemoine, Frank; Crossley, David; Boy, Jean-Paul

2006-01-01

This paper is devoted to the investigation of seasonal changes of the Earth's gravity field from GRACE satellites and the comparison with surface gravity measurements in Europe from the Global Geodynamics Project (GGP) sub-network, as well as with recent hydrology models for continental soil moisture and snow. We used gravity maps in Europe retrieved from the initial GRACE monthly solutions spanning a 21-month duration from April 2002 to December 2003 for various truncation levels of the initial spherical harmonic decomposition of the field. The transfer function between satellite-derived and ground gravity changes due to continental hydrology is studied and we also compute the theoretical ratio of gravity versus radial displacement (in μGal/mm) involved in the hydrological loading process. The 'mean' value (averaged in time and in space over Europe) from hydrologic forward modeling is found to be close to -1.0 μGal/mm and we show that this value can be explained by a strong low degree ( n = 5-6) peak in the hydrology amplitude spectrum. The dominant time-variable signal from GRACE is found to be annual with an amplitude and a phase both of which are in fair agreement with predictions in Europe from recent hydrology models. Initial results suggest that all three data sets (GRACE, hydrology and GGP) respond to annual changes in near-surface water in Europe of a few μGal (at length scales of ˜1000 km) that show a high value in winter and a summer minimum. Despite the limited time span of our analysis and the uncertainties in separating purely local effects from regional ones in superconducting gravimeter data, the calibration and validation aspects of the GRACE data processing based on the annual hydrology cycle in Europe are in progress.

Monitoring climate and man-made induced variations in terrestrial water storage (TWS) across Africa using GRACE data

Science.gov (United States)

Ahmed, M. E.; Sultan, M.; Wahr, J. M.; Yan, E.; Bonin, J. A.; Chouinard, K.

2012-12-01

It is common practice for researchers engaged in research related to climate change to examine the temporal variations in relevant climatic parameters (e.g., temperature, precipitation) and to extract and examine drought indices reproduced from one or more such parameters. Drought indices (meteorological, agricultural and hydrological) define departures from normal conditions and are used as proxies for monitoring water availability. Many of these indices exclude significant controlling factor(s), do not work well in specific settings and regions, and often require long (≥50 yr) calibration time periods and substantial meteorological data, limiting their application in areas lacking adequate observational networks. Additional uncertainties are introduced by the models used in computing model-dependent indices. Aside from these uncertainties, none of these indices measure the variability in terrestrial water storage (TWS), a term that refers to the total vertically integrated water content in an area regardless of the reservoir in which it resides. Inter-annual trends in TWS were extracted from monthly Gravity Recovery and Climate Experiment (GRACE) data acquired (04/2002 to 08/2011) over Africa and correlated (in a GIS environment) with relevant temporal remote sensing, geologic, hydrologic, climatic, and topographic datasets. Findings include the following: (1) large sectors of Africa are undergoing statistically significant variations (+36 mm/yr to -16 mm/yr) due to natural and man-made causes; (2) warming of the tropical Atlantic ocean apparently intensified Atlantic monsoons and increased precipitation and TWS over western and central Africa's coastal plains, proximal mountainous source areas, and inland areas as far as central Chad; (3) warming in the central Indian Ocean decreased precipitation and TWS over eastern and southern Africa; (4) the high frequency of negative phases of the North Atlantic Oscillation (NAO) increased precipitation and TWS over

Comparison of RISK-PCI, GRACE, TIMI risk scores for prediction of major adverse cardiac events in patients with acute coronary syndrome.

Science.gov (United States)

Jakimov, Tamara; Mrdović, Igor; Filipović, Branka; Zdravković, Marija; Djoković, Aleksandra; Hinić, Saša; Milić, Nataša; Filipović, Branislav

2017-12-31

To compare the prognostic performance of three major risk scoring systems including global registry for acute coronary events (GRACE), thrombolysis in myocardial infarction (TIMI), and prediction of 30-day major adverse cardiovascular events after primary percutaneous coronary intervention (RISK-PCI). This single-center retrospective study involved 200 patients with acute coronary syndrome (ACS) who underwent invasive diagnostic approach, ie, coronary angiography and myocardial revascularization if appropriate, in the period from January 2014 to July 2014. The GRACE, TIMI, and RISK-PCI risk scores were compared for their predictive ability. The primary endpoint was a composite 30-day major adverse cardiovascular event (MACE), which included death, urgent target-vessel revascularization (TVR), stroke, and non-fatal recurrent myocardial infarction (REMI). The c-statistics of the tested scores for 30-day MACE or area under the receiver operating characteristic curve (AUC) with confidence intervals (CI) were as follows: RISK-PCI (AUC=0.94; 95% CI 1.790-4.353), the GRACE score on admission (AUC=0.73; 95% CI 1.013-1.045), the GRACE score on discharge (AUC=0.65; 95% CI 0.999-1.033). The RISK-PCI score was the only score that could predict TVR (AUC=0.91; 95% CI 1.392-2.882). The RISK-PCI scoring system showed an excellent discriminative potential for 30-day death (AUC=0.96; 95% CI 1.339-3.548) in comparison with the GRACE scores on admission (AUC=0.88; 95% CI 1.018-1.072) and on discharge (AUC=0.78; 95% CI 1.000-1.058). In comparison with the GRACE and TIMI scores, RISK-PCI score showed a non-inferior ability to predict 30-day MACE and death in ACS patients. Moreover, RISK-PCI was the only scoring system that could predict recurrent ischemia requiring TVR.

76 FR 10899 - Decision To Evaluate a Petition To Designate a Class of Employees From the W.R. Grace and Company...

Science.gov (United States)

2011-02-28

... Employees From the W.R. Grace and Company in Curtis, MD, To Be Included in the Special Exposure Cohort... evaluate a petition to designate a class of employees from the W.R. Grace and Company in Curtis, Maryland... Compensation Program Act of 2000. The initial proposed definition for the class being evaluated, subject to...

Predictive values of D-dimer assay, GRACE scores and TIMI scores for adverse outcome in patients with non-ST-segment elevation myocardial infarction

Science.gov (United States)

Satilmisoglu, Muhammet Hulusi; Ozyilmaz, Sinem Ozbay; Gul, Mehmet; Ak Yildirim, Hayriye; Kayapinar, Osman; Gokturk, Kadir; Aksu, Huseyin; Erkanli, Korhan; Eksik, Abdurrahman

2017-01-01

Purpose To determine the predictive values of D-dimer assay, Global Registry of Acute Coronary Events (GRACE) and Thrombolysis in Myocardial Infarction (TIMI) risk scores for adverse outcome in patients with non-ST-segment elevation myocardial infarction (NSTEMI). Patients and methods A total of 234 patients (mean age: 57.2±11.7 years, 75.2% were males) hospitalized with NSTEMI were included. Data on D-dimer assay, GRACE and TIMI risk scores were recorded. Logistic regression analysis was conducted to determine the risk factors predicting increased mortality. Results Median D-dimer levels were 349.5 (48.0–7,210.0) ng/mL, the average TIMI score was 3.2±1.2 and the GRACE score was 90.4±27.6 with high GRACE scores (>118) in 17.5% of patients. The GRACE score was correlated positively with both the D-dimer assay (r=0.215, P=0.01) and TIMI scores (r=0.504, P=0.000). Multivariate logistic regression analysis revealed that higher creatinine levels (odds ratio =18.465, 95% confidence interval: 1.059–322.084, P=0.046) constituted the only significant predictor of increased mortality risk with no predictive values for age, D-dimer assay, ejection fraction, glucose, hemoglobin A1c, sodium, albumin or total cholesterol levels for mortality. Conclusion Serum creatinine levels constituted the sole independent determinant of mortality risk, with no significant values for D-dimer assay, GRACE or TIMI scores for predicting the risk of mortality in NSTEMI patients. PMID:28408834

Water Storage Changes over the Tibetan Plateau Revealed by GRACE Mission

Science.gov (United States)

Guo, Jinyun; Mu, Dapeng; Liu, Xin; Yan, Haoming; Sun, Zhongchang; Guo, Bin

2016-04-01

We use GRACE gravity data released by the Center for Space Research (CSR) and the Groupe de Recherches en Geodesie Spatiale (GRGS) to detect the water storage changes over the Tibetan Plateau (TP). A combined filter strategy is put forward to process CSR RL05 data to remove the effect of striping errors. After the correction for GRACE by GLDAS and ICE-5G, we find that TP has been overall experiencing the water storage increase during 2003-2012. During the same time, the glacier over the Himalayas was sharply retreating. Interms of linear trends, CSR's results derived by the combined filter are close to GRGS RL03 with the Gaussian filter of 300-km window. The water storage increasing rates determined from CSR's RL05 products in the interior TP, Karakoram Mountain, Qaidam Basin, Hengduan Mountain, and middle Himalayas are 9.7, 6.2, 9.1,-18.6, and-20.2 mm/yr, respectively. These rates from GRGS's RL03 products are 8.6, 5.8, 10.5,-19.3 and-21.4 mm/yr, respectively.

Project GRACE A grid based search tool for the global digital library

CERN Document Server

Scholze, Frank; Vigen, Jens; Prazak, Petra; The Seventh International Conference on Electronic Theses and Dissertations

2004-01-01

The paper will report on the progress of an ongoing EU project called GRACE - Grid Search and Categorization Engine (http://www.grace-ist.org). The project participants are CERN, Sheffield Hallam University, Stockholm University, Stuttgart University, GL 2006 and Telecom Italia. The project started in 2002 and will finish in 2005, resulting in a Grid based search engine that will search across a variety of content sources including a number of electronic thesis and dissertation repositories. The Open Archives Initiative (OAI) is expanding and is clearly an interesting movement for a community advocating open access to ETD. However, the OAI approach alone may not be sufficiently scalable to achieve a truly global ETD Digital Library. Many universities simply offer their collections to the world via their local web services without being part of any federated system for archiving and even those dissertations that are provided with OAI compliant metadata will not necessarily be picked up by a centralized OAI Ser...

Global and regional seasonal variations of the geoid detected by GRACE

Czech Academy of Sciences Publication Activity Database

Kostelecký, J.; Bezděk, Aleš; Klokočník, Jaroslav

2013-01-01

Roč. 10, č. 3 (2013), s. 285-291 ISSN 1214-9705 R&D Projects: GA ČR GA13-36843S Grant - others:EU(XE) NTIS CZ1.05/1.1.00/02.0090 Institutional support: RVO:67985815 Keywords : GRACE mission * seasonal variations * geoid Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 0.667, year: 2013

Inferring Large-Scale Terrestrial Water Storage Through GRACE and GPS Data Fusion in Cloud Computing Environments

Science.gov (United States)

Rude, C. M.; Li, J. D.; Gowanlock, M.; Herring, T.; Pankratius, V.

2016-12-01

Surface subsidence due to depletion of groundwater can lead to permanent compaction of aquifers and damaged infrastructure. However, studies of such effects on a large scale are challenging and compute intensive because they involve fusing a variety of data sets beyond direct measurements from groundwater wells, such as gravity change measurements from the Gravity Recovery and Climate Experiment (GRACE) or surface displacements measured by GPS receivers. Our work therefore leverages Amazon cloud computing to enable these types of analyses spanning the entire continental US. Changes in groundwater storage are inferred from surface displacements measured by GPS receivers stationed throughout the country. Receivers located on bedrock are anti-correlated with changes in water levels from elastic deformation due to loading, while stations on aquifers correlate with groundwater changes due to poroelastic expansion and compaction. Correlating linearly detrended equivalent water thickness measurements from GRACE with linearly detrended and Kalman filtered vertical displacements of GPS stations located throughout the United States helps compensate for the spatial and temporal limitations of GRACE. Our results show that the majority of GPS stations are negatively correlated with GRACE in a statistically relevant way, as most GPS stations are located on bedrock in order to provide stable reference locations and measure geophysical processes such as tectonic deformations. Additionally, stations located on the Central Valley California aquifer show statistically significant positive correlations. Through the identification of positive and negative correlations, deformation phenomena can be classified as loading or poroelastic expansion due to changes in groundwater. This method facilitates further studies of terrestrial water storage on a global scale. This work is supported by NASA AIST-NNX15AG84G (PI: V. Pankratius) and Amazon.

RCRA Facility Investigation/Remedial Investigation Report for the Grace Road Site (631-22G)

Energy Technology Data Exchange (ETDEWEB)

Palmer, E.

1998-10-02

This report summarizes the activities and documents the results of a Resource Conservation and Recovery Act Facility Investigation/Remedial Investigation conducted at Grace Road Site on the Savannah River Site near Aiken, South Carolina.

RCRA Facility Investigation/Remedial Investigation Report for the Grace Road Site (631-22G)

International Nuclear Information System (INIS)

Palmer, E.

1998-01-01

This report summarizes the activities and documents the results of a Resource Conservation and Recovery Act Facility Investigation/Remedial Investigation conducted at Grace Road Site on the Savannah River Site near Aiken, South Carolina

Terrestrial water storage changes over the Pearl River Basin from GRACE and connections with Pacific climate variability

Directory of Open Access Journals (Sweden)

Zhicai Luo

2016-05-01

Full Text Available Time-variable gravity data from the Gravity Recovery and Climate Experiment (GRACE satellite mission are used to study terrestrial water storage (TWS changes over the Pearl River Basin (PRB for the period 2003–Nov. 2014. TWS estimates from GRACE generally show good agreement with those from two hydrological models GLDAS and WGHM. But they show different capability of detecting significant TWS changes over the PRB. Among them, WGHM is likely to underestimate the seasonal variability of TWS, while GRACE detects long-term water depletions over the upper PRB as was done by hydrological models, and observes significant water increases around the Longtan Reservoir (LTR due to water impoundment. The heavy drought in 2011 caused by the persistent precipitation deficit has resulted in extreme low surface runoff and water level of the LTR. Moreover, large variability of summer and autumn precipitation may easily trigger floods and droughts in the rainy season in the PRB, especially for summer, as a high correlation of 0.89 was found between precipitation and surface runoff. Generally, the PRB TWS was negatively correlated with El Niño-Southern Oscillation (ENSO events. However, the modulation of the Pacific Decadal Oscillation (PDO may impact this relationship, and the significant TWS anomaly was likely to occur in the peak of PDO phase as they agree well in both of the magnitude and timing of peaks. This indicates that GRACE-based TWS could be a valuable parameter for studying climatic influences in the PRB.

Mass-induced sea level variations in the Red Sea from GRACE, steric-corrected altimetry, in situ bottom pressure records, and hydrographic observations

Science.gov (United States)

Feng, W.; Lemoine, J.-M.; Zhong, M.; Hsu, H. T.

2014-08-01

An annual amplitude of ∼18 cm mass-induced sea level variations (SLV) in the Red Sea is detected from the Gravity Recovery and Climate Experiment (GRACE) satellites and steric-corrected altimetry from 2003 to 2011. The annual mass variations in the region dominate the mean SLV, and generally reach maximum in late January/early February. The annual steric component of the mean SLV is relatively small (mass-induced SLV. In situ bottom pressure records at the eastern coast of the Red Sea validate the high mass variability observed by steric-corrected altimetry and GRACE. In addition, the horizontal water mass flux of the Red Sea estimated from GRACE and steric-corrected altimetry is validated by hydrographic observations.

Water storage changes in North America retrieved from GRACE gravity and GPS data

Directory of Open Access Journals (Sweden)

Hansheng Wang

2015-07-01

Full Text Available As global warming continues, the monitoring of changes in terrestrial water storage becomes increasingly important since it plays a critical role in understanding global change and water resource management. In North America as elsewhere in the world, changes in water resources strongly impact agriculture and animal husbandry. From a combination of Gravity Recovery and Climate Experiment (GRACE gravity and Global Positioning System (GPS data, it is recently found that water storage from August, 2002 to March, 2011 recovered after the extreme Canadian Prairies drought between 1999 and 2005. In this paper, we use GRACE monthly gravity data of Release 5 to track the water storage change from August, 2002 to June, 2014. In Canadian Prairies and the Great Lakes areas, the total water storage is found to have increased during the last decade by a rate of 73.8 ± 14.5 Gt/a, which is larger than that found in the previous study due to the longer time span of GRACE observations used and the reduction of the leakage error. We also find a long term decrease of water storage at a rate of −12.0 ± 4.2 Gt/a in Ungava Peninsula, possibly due to permafrost degradation and less snow accumulation during the winter in the region. In addition, the effect of total mass gain in the surveyed area, on present-day sea level, amounts to −0.18 mm/a, and thus should be taken into account in studies of global sea level change.

Analysis of Groundwater Anomalies Estimated by GRACE and GLDAS Satellite-based Hydrological Model in the Gulf of Mexico

Science.gov (United States)

Lotfata, A.; Ambinakudige, S.

2017-12-01

Coastal regions face a higher risk of flooding. A rise in sea-level increases flooding chances in low-lying areas. A major concern is the effect of sea-level rise on the depth of the fresh water/salt water interface in the aquifers of the coastal regions. A sea-level change rise impacts the hydrological system of the aquifers. Salt water intrusion into fresh water aquifers increase water table levels. Flooding prone areas in the coast are at a higher risk of salt water intrusion. The Gulf coast is one of the most vulnerable flood areas due to its natural weather patterns. There is not yet a local assessment of the relation between groundwater level and sea-level rising. This study investigates the projected sea-level rise models and the anomalous groundwater level during January 2002 to December 2016. We used the NASA Gravity Recovery and Climate Experiment (GRACE) and Global Land Data Assimilation System (GLDAS) satellite data in the analysis. We accounted the leakage error and the measurement error in GRACE data. GLDAS data was used to calculate the groundwater storage from the total water storage estimated using GRACE data (ΔGW=ΔTWS (soil moisture, surface water, groundwater, and canopy water) - ΔGLDAS (soil moisture, surface water, and canopy water)). The preliminary results indicate that the total water storage is increasing in parts of the Gulf of Mexico. GRACE data show high soil wetness and groundwater levels in Mississippi, Alabama and Texas coasts. Because sea-level rise increases the probability of flooding in the Gulf coast and affects the groundwater, we will analyze probable interactions between sea-level rise and groundwater in the study area. To understand regional sea-level rise patterns, we will investigate GRACE Ocean data along the Gulf coasts. We will quantify ocean total water storage, its salinity, and its relationship with the groundwater level variations in the Gulf coast.

Augustin Erath's reconciliation of Thomist and Molinist Doctrines on Grace and Free Human Action

Czech Academy of Sciences Publication Activity Database

Dvořák, Petr

2016-01-01

Roč. 64, Suppl. (2016), s. 185-207 ISSN 0015-1831 R&D Projects: GA ČR GB14-37038G Institutional support: RVO:67985955 Keywords : free will * divine action * divine causation * grace Subject RIV: AA - Philosophy ; Religion

Insights into the Earth System mass variability from CSR-RL05 GRACE gravity fields

Science.gov (United States)

Bettadpur, S.

2012-04-01

The next-generation Release-05 GRACE gravity field data products are the result of extensive effort applied to the improvements to the GRACE Level-1 (tracking) data products, and to improvements in the background gravity models and processing methodology. As a result, the squared-error upper-bound in RL05 fields is half or less than the squared-error upper-bound in RL04 fields. The CSR-RL05 field release consists of unconstrained gravity fields as well as a regularized gravity field time-series that can be used for several applications without any post-processing error reduction. This paper will describe the background and the nature of these improvements in the data products, and provide an error characterization. We will describe the insights these new series offer in measuring the mass flux due to diverse Hydrologic, Oceanographic and Cryospheric processes.

Flight-Like Optical Reference Cavity for GRACE Follow-On Laser Frequency Stabilization

Science.gov (United States)

Folkner, W. M.; deVine, G.; Klipstein, W. M.; McKenzie, K.; Spero, R.; Thompson, R.; Yu, N.; Stephens, M.; Leitch, J.; Pierce, R.;

A Test Run of the EGSIEM Near Real-Time Service Based on GRACE Mission Data

Science.gov (United States)

Kvas, A.; Gruber, C.; Gouweleeuw, B.; Guntner, A.; Mayer-Gürr, T.; Flechtner, F. M.

2017-12-01

To enable the use of GRACE and GRACE-FO data for rapid monitoring applications, the EGSIEM (European Gravity Service for Improved Emergency Management) project, funded by the Horizon 2020 Framework Program for Research and Innovation of the European Union, has implemented a demonstrator for a near real-time (NRT) gravity field service. The goal of this service is to provide daily gravity field solutions with a maximum latency of five days. For this purpose, two independent approaches were developed at the German Research Centre for Geosciences (GFZ) and Graz University of Technology (TUG). Based on these daily gravity field solutions, statistical flood and drought indicators are derived by the EGSIEM Hydrological Service, developed at GFZ. The NRT products are subsequently provided to the Center for Satellite based Crisis Information (ZKI) at the German Aerospace Center as well as the Global Flood Awareness System (GloFAS) at the Joint Research Center of the European Commission. In the first part of this contribution, the performance of the service based on a statistical analysis of historical flood events during the GRACE period is evaluated. Then, results from the six month long operational test run of the service which started on April 1st 2017 are presented and a comparison between historical and operational gravity products and flood indicators is made.

Improved estimates of global sea level change from Ice Sheets, glaciers and land water storage using GRACE

Science.gov (United States)

Velicogna, I.; Hsu, C. W.; Ciraci, E.; Sutterley, T. C.

2015-12-01

We use observations of time variable gravity from GRACE to estimate mass changes for the Antarctic and Greenland Ice Sheets, the Glaciers and Ice Caps (GIC) and land water storage for the time period 2002-2015 and evaluate their total contribution to sea level. We calculate regional sea level changes from these present day mass fluxes using an improved scaling factor for the GRACE data that accounts for the spatial and temporal variability of the observed signal. We calculate a separate scaling factor for the annual and the long-term components of the GRACE signal. To estimate the contribution of the GIC, we use a least square mascon approach and we re-analyze recent inventories to optimize the distribution of mascons and recover the GRACE signal more accurately. We find that overall, Greenland controls 43% of the global trend in eustatic sea level rise, 16% for Antarctica and 29% for the GIC. The contribution from the GIC is dominated by the mass loss of the Canadian Arctic Archipelago, followed by Alaska, Patagonia and the High Mountains of Asia. We report a marked increase in mass loss for the Canadian Arctic Archipelago. In Greenland, following the 2012 high summer melt, years 2013 and 2014 have slowed down the increase in mass loss, but our results will be updated with summer 2015 observations at the meeting. In Antarctica, the mass loss is still on the rise with increased contributions from the Amundsen Sea sector and surprisingly from the Wilkes Land sector of East Antarctica, including Victoria Land. Conversely, the Queen Maud Land sector experienced a large snowfall in 2009-2013 and has now resumed to a zero mass gain since 2013. We compare sea level changes from these GRACE derived mass fluxes after including the atmospheric and ocean loading signal with sea level change from satellite radar altimetry (AVISO) corrected for steric signal of the ocean using Argo measurements and find an excellent agreement in amplitude, phase and trend in these estimates

Identification of Outliers in Grace Data for Indo-Gangetic Plain Using Various Methods (Z-Score, Modified Z-score and Adjusted Boxplot) and Its Removal

Science.gov (United States)

Srivastava, S.

2015-12-01

Gravity Recovery and Climate Experiment (GRACE) data are widely used for the hydrological studies for large scale basins (≥100,000 sq km). GRACE data (Stokes Coefficients or Equivalent Water Height) used for hydrological studies are not direct observations but result from high level processing of raw data from the GRACE mission. Different partner agencies like CSR, GFZ and JPL implement their own methodology and their processing methods are independent from each other. The primary source of errors in GRACE data are due to measurement and modeling errors and the processing strategy of these agencies. Because of different processing methods, the final data from all the partner agencies are inconsistent with each other at some epoch. GRACE data provide spatio-temporal variations in Earth's gravity which is mainly attributed to the seasonal fluctuations in water level on Earth surfaces and subsurface. During the quantification of error/uncertainties, several high positive and negative peaks were observed which do not correspond to any hydrological processes but may emanate from a combination of primary error sources, or some other geophysical processes (e.g. Earthquakes, landslide, etc.) resulting in redistribution of earth's mass. Such peaks can be considered as outliers for hydrological studies. In this work, an algorithm has been designed to extract outliers from the GRACE data for Indo-Gangetic plain, which considers the seasonal variations and the trend in data. Different outlier detection methods have been used such as Z-score, modified Z-score and adjusted boxplot. For verification, assimilated hydrological (GLDAS) and hydro-meteorological data are used as the reference. The results have shown that the consistency amongst all data sets improved significantly after the removal of outliers.

Eternal extended inflation and graceful exit from old inflation without Jordan-Brans-Dicke

International Nuclear Information System (INIS)

Linde, A.

1990-01-01

Recently a possible solution to the graceful exit problem of the old inflation was proposed in the context of the Jordan-Brans-Dicke theory (extended inflation). In this paper we will argue that inflation in this theory occurs in a most natural way if it starts near the Planck density, as in the standard version of chaotic inflation. With most natural initial conditions, the inflationary universe in the JBD theory enters the stage of permanent reproduction of new inflationary domains (eternal extended inflation). In order to realize the extended inflation scenario at least two classical scalar fields driving inflation are necessary, as distinct from the simplest versions of new and chaotic inflation. It is shown that in the theory of two scalar fields one can solve the graceful exit problem even without modifying the Einstein gravity theory, due to the possibility that the decay rate of the false vacuum in old inflation depends on the value of the second scalar field and hence on time. (orig.)

Monthly gravity field recovery from GRACE orbits and K-band measurements using variational equations approach

Directory of Open Access Journals (Sweden)

Changqing Wang

2015-07-01

Full Text Available The Gravity Recovery and Climate Experiment (GRACE mission can significantly improve our knowledge of the temporal variability of the Earth's gravity field. We obtained monthly gravity field solutions based on variational equations approach from GPS-derived positions of GRACE satellites and K-band range-rate measurements. The impact of different fixed data weighting ratios in temporal gravity field recovery while combining the two types of data was investigated for the purpose of deriving the best combined solution. The monthly gravity field solution obtained through above procedures was named as the Institute of Geodesy and Geophysics (IGG temporal gravity field models. IGG temporal gravity field models were compared with GRACE Release05 (RL05 products in following aspects: (i the trend of the mass anomaly in China and its nearby regions within 2005–2010; (ii the root mean squares of the global mass anomaly during 2005–2010; (iii time-series changes in the mean water storage in the region of the Amazon Basin and the Sahara Desert between 2005 and 2010. The results showed that IGG solutions were almost consistent with GRACE RL05 products in above aspects (i–(iii. Changes in the annual amplitude of mean water storage in the Amazon Basin were 14.7 ± 1.2 cm for IGG, 17.1 ± 1.3 cm for the Centre for Space Research (CSR, 16.4 ± 0.9 cm for the GeoForschungsZentrum (GFZ and 16.9 ± 1.2 cm for the Jet Propulsion Laboratory (JPL in terms of equivalent water height (EWH, respectively. The root mean squares of the mean mass anomaly in Sahara were 1.2 cm, 0.9 cm, 0.9 cm and 1.2 cm for temporal gravity field models of IGG, CSR, GFZ and JPL, respectively. Comparison suggested that IGG temporal gravity field solutions were at the same accuracy level with the latest temporal gravity field solutions published by CSR, GFZ and JPL.

Predictive values of D-dimer assay, GRACE scores and TIMI scores for adverse outcome in patients with non-ST-segment elevation myocardial infarction

Directory of Open Access Journals (Sweden)

Satilmisoglu MH

2017-03-01

Full Text Available Muhammet Hulusi Satilmisoglu,1 Sinem Ozbay Ozyilmaz,1 Mehmet Gul,1 Hayriye Ak Yildirim,2 Osman Kayapinar,3 Kadir Gokturk,4 Huseyin Aksu,1 Korhan Erkanli,5 Abdurrahman Eksik1 1Department of Cardiology, 2Department of Biochemistry, Mehmet Akif Ersoy Thoracic and Cardiovascular Surgery Training and Research Hospital, Istanbul, 3Department of Cardiology, Duzce University Faculty of Medicine, Duzce, 4Department of Infectious Diseases, 5Department of Thoracic and Cardiovascular Surgery, Mehmet Akif Ersoy Thoracic and Cardiovascular Surgery Training and Research Hospital, Istanbul, Turkey Purpose: To determine the predictive values of D-dimer assay, Global Registry of Acute Coronary Events (GRACE and Thrombolysis in Myocardial Infarction (TIMI risk scores for adverse outcome in patients with non-ST-segment elevation myocardial infarction (NSTEMI.Patients and methods: A total of 234 patients (mean age: 57.2±11.7 years, 75.2% were males hospitalized with NSTEMI were included. Data on D-dimer assay, GRACE and TIMI risk scores were recorded. Logistic regression analysis was conducted to determine the risk factors predicting increased mortality.Results: Median D-dimer levels were 349.5 (48.0–7,210.0 ng/mL, the average TIMI score was 3.2±1.2 and the GRACE score was 90.4±27.6 with high GRACE scores (>118 in 17.5% of patients. The GRACE score was correlated positively with both the D-dimer assay (r=0.215, P=0.01 and TIMI scores (r=0.504, P=0.000. Multivariate logistic regression analysis revealed that higher creatinine levels (odds ratio =18.465, 95% confidence interval: 1.059–322.084, P=0.046 constituted the only significant predictor of increased mortality risk with no predictive values for age, D-dimer assay, ejection fraction, glucose, hemoglobin A1c, sodium, albumin or total cholesterol levels for mortality.Conclusion: Serum creatinine levels constituted the sole independent determinant of mortality risk, with no significant values for D

Can GRACE Explain Some of the Main Interannual Polar Motion Signatures?

Science.gov (United States)

Adhikari, S.; Ivins, E. R.; Larour, E. Y.

2016-12-01

GRACE has provided a series of monthly solutions for water mass transport that now span a 14-year period. A natural question to ask is how much of this mass transport information might be used to reconstruct, theoretically, the non-tidal and non-Chandlerian polar motion at interannual time scales. Reconstruction of the pole position at interannual time scales since 2002 has been performed by Chen et al. (2013, GRL) and Adhikari and Ivins (2016, Science Advances). (The main feature of polar motion that has been evolving since the mid 1990's is the increasing dominance of Greenland ice mass loss.) Here we discuss this reconstruction and the level of error that occurs because of missing information about the spherical harmonic degree 1 and 2 terms and the lack of terms associated with angular momentum transfer in the Louiville equations. Using GRACE observations and complementary solutions of self-attraction/loading problem on an elastically compressible rotating earth, we show that ice mass losses from polar ice sheets, and when combined with changes in continental hydrology, explain nearly the entire amplitude (83±23%) and mean directional shift (within 5.9±7.6°) of recently observed eastward polar motion. We also show that decadal scale pole variations are directly linked to global changes in continental hydrology. The energy sources for such motions are likely to be associated with decadal scale ocean and atmospheric oscillations that also drive 20th century continental wet-dry variability. Interannual variability in pole position, therefore, offers a tool for assessing past stability of our climate, and for the future, now faced with an increased intensity in the water cycle and more vulnerable to ice sheet instability. Figure caption: Observed and reconstructed mean annual pole positions with respect to the 2003-2015 mean position. Blue error band is associated with the reconstructed solution; red signifies additional errors that are related to uncertainty in

Non-Linear Non Stationary Analysis of Two-Dimensional Time-Series Applied to GRACE Data, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — The proposed innovative two-dimensional (2D) empirical mode decomposition (EMD) analysis was applied to NASA's Gravity Recovery and Climate Experiment (GRACE)...

Climate-driven seasonal geocenter motion during the GRACE period

Science.gov (United States)

Zhang, Hongyue; Sun, Yu

2018-03-01

Annual cycles in the geocenter motion time series are primarily driven by mass changes in the Earth's hydrologic system, which includes land hydrology, atmosphere, and oceans. Seasonal variations of the geocenter motion have been reliably determined according to Sun et al. (J Geophys Res Solid Earth 121(11):8352-8370, 2016) by combining the Gravity Recovery And Climate Experiment (GRACE) data with an ocean model output. In this study, we reconstructed the observed seasonal geocenter motion with geophysical model predictions of mass variations in the polar ice sheets, continental glaciers, terrestrial water storage (TWS), and atmosphere and dynamic ocean (AO). The reconstructed geocenter motion time series is shown to be in close agreement with the solution based on GRACE data supporting with an ocean bottom pressure model. Over 85% of the observed geocenter motion time series, variance can be explained by the reconstructed solution, which allows a further investigation of the driving mechanisms. We then demonstrated that AO component accounts for 54, 62, and 25% of the observed geocenter motion variances in the X, Y, and Z directions, respectively. The TWS component alone explains 42, 32, and 39% of the observed variances. The net mass changes over oceans together with self-attraction and loading effects also contribute significantly (about 30%) to the seasonal geocenter motion in the X and Z directions. Other contributing sources, on the other hand, have marginal (less than 10%) impact on the seasonal variations but introduce a linear trend in the time series.

Glacier mass variations from recent ITSG-Grace solutions: Experiences with the point-mass modeling technique in the framework of project SPICE.

Science.gov (United States)

Reimond, S.; Klinger, B.; Krauss, S.; Mayer-Gürr, T.; Eicker, A.; Zemp, M.

2017-12-01

In recent years, remotely sensed observations have become one of the most ubiquitous and valuable sources of information for glacier monitoring. In addition to altimetry and interferometry data (as observed, e.g., by the CryoSat-2 and TanDEM-X satellites), time-variable gravity field data from the GRACE satellite mission has been used by several authors to assess mass changes in glacier systems. The main challenges in this context are i) the limited spatial resolution of GRACE, ii) the gravity signal attenuation in space and iii) the problem of isolating the glaciological signal from the gravitational signatures as detected by GRACE.In order to tackle the challenges i) and ii), we thoroughly investigate the point-mass modeling technique to represent the local gravity field. Instead of simply evaluating global spherical harmonics, we operate on the normal equation level and make use of GRACE K-band ranging data (available since April 2002) processed at the Graz University of Technology. Assessing such small-scale mass changes from space-borne gravimetric data is an ill-posed problem, which we aim to stabilize by utilizing a Genetic Algorithm based Tikhonov regularization. Concerning issue iii), we evaluate three different hydrology models (i.e. GLDAS, LSDM and WGHM) for validation purposes and the derivation of error bounds. The non-glaciological signal is calculated for each region of interest and reduced from the GRACE results.We present mass variations of several alpine glacier systems (e.g. the European Alps, Svalbard or Iceland) and compare our results to glaciological observations provided by the World Glacier Monitoring Service (WGMS) and alternative inversion methods (surface density modeling).

Inter-comparison of ice sheet mass balance products from GRACE: ESA CCI Round Robin results

DEFF Research Database (Denmark)

Groth, A.; Horwath, M.; Horvath, A.

-term satellite-based data products are generated for selected ECVs. Since ice sheet mass balance is an ECV parameter of highest interest, both the AIS_cci and the GIS_cci project will provide mass balance products based on satellite gravimetry data: (a) time series of monthly mass changes for individual drainage...... basins, and (b) gridded mass changes covering the entire ice sheet.Gravimetry Mass Balance (GMB) products are derived from data acquired by the GRACE (Gravity Recovery and Climate Experiment) mission. Although GRACE data have the advantage of being directly sensitive to mass changes, their limited...... drainage basins the GMB time series are compared to independent mass balance products based on satellite altimetry and firn densification information from a regional climate model. This inter-comparison has aided the algorithm definition for the operational ECV production....

The potential of GRACE gravimetry to detect the heavy rainfall-induced impoundment of a small reservoir in the upper Yellow River

OpenAIRE

Yi, Shuang; Song, Chunqiao; Wang, Qiuyu; Wang, Linsong; Heki, Kosuke; Sun, Wenke

2017-01-01

Artificial reservoirs are important indicators of anthropogenic impacts on environments, and their cumulative influences on the local water storage will change the gravity signal. However, because of their small signal size, such gravity changes are seldom studied using satellite gravimetry from the Gravity Recovery and Climate Experiment (GRACE). Here we investigate the ability of GRACE to detect water storage changes in the Longyangxia Reservoir (LR), which is situated in the uppe...

Satellite altimetry and GRACE gravimetry for studies of annual water storage variations in Bangladesh

DEFF Research Database (Denmark)

Andersen, Ole Baltazar; Berry, P.; Freeman, J.

2008-01-01

Four different data sources have been compared with respect to observations of the annual water storage variations in the region of Bangladesh. Data from satellite altimeters and river gauges estimates the variation in surface water storage in the major rivers of Bangladesh. The GRACE satellites ...

Towards Year-round Estimation of Terrestrial Water Storage over Snow-Covered Terrain via Multi-sensor Assimilation of GRACE/GRACE-FO and AMSR-E/AMSR-2.

Science.gov (United States)

Wang, J.; Xue, Y.; Forman, B. A.; Girotto, M.; Reichle, R. H.

2017-12-01

The Gravity and Recovery Climate Experiment (GRACE) has revolutionized large-scale remote sensing of the Earth's terrestrial hydrologic cycle and has provided an unprecedented observational constraint for global land surface models. However, the coarse-scale (in space and time), vertically-integrated measure of terrestrial water storage (TWS) limits GRACE's applicability to smaller scale hydrologic applications. In order to enhance model-based estimates of TWS while effectively adding resolution (in space and time) to the coarse-scale TWS retrievals, a multi-variate, multi-sensor data assimilation framework is presented here that simultaneously assimilates gravimetric retrievals of TWS in conjunction with passive microwave (PMW) brightness temperature (Tb) observations over snow-covered terrain. The framework uses the NASA Catchment Land Surface Model (Catchment) and an ensemble Kalman filter (EnKF). A synthetic assimilation experiment is presented for the Volga river basin in Russia. The skill of the output from the assimilation of synthetic observations is compared with that of model estimates generated without the benefit of assimilating the synthetic observations. It is shown that the EnKF framework improves modeled estimates of TWS, snow depth, and snow mass (a.k.a. snow water equivalent). The data assimilation routine produces a conditioned (updated) estimate that is more accurate and contains less uncertainty during both the snow accumulation phase of the snow season as well as during the snow ablation season.

Seasonal Mass Changes and Crustal Vertical Deformations Constrained by GPS and GRACE in Northeastern Tibet

Directory of Open Access Journals (Sweden)

Yuanjin Pan

2016-08-01

Full Text Available Surface vertical deformation includes the Earth’s elastic response to mass loading on or near the surface. Continuous Global Positioning System (CGPS stations record such deformations to estimate seasonal and secular mass changes. We used 41 CGPS stations to construct a time series of coordinate changes, which are decomposed by empirical orthogonal functions (EOFs, in northeastern Tibet. The first common mode shows clear seasonal changes, indicating seasonal surface mass re-distribution around northeastern Tibet. The GPS-derived result is then assessed in terms of the mass changes observed in northeastern Tibet. The GPS-derived common mode vertical change and the stacked Gravity Recovery and Climate Experiment (GRACE mass change are consistent, suggesting that the seasonal surface mass variation is caused by changes in the hydrological, atmospheric and non-tidal ocean loads. The annual peak-to-peak surface mass changes derived from GPS and GRACE results show seasonal oscillations in mass loads, and the corresponding amplitudes are between 3 and 35 mm/year. There is an apparent gradually increasing gravity between 0.1 and 0.9 μGal/year in northeast Tibet. Crustal vertical deformation is determined after eliminating the surface load effects from GRACE, without considering Glacial Isostatic Adjustment (GIA contribution. It reveals crustal uplift around northeastern Tibet from the corrected GPS vertical velocity. The unusual uplift of the Longmen Shan fault indicates tectonically sophisticated processes in northeastern Tibet.

Establishing a Global Radiation Oncology Collaboration in Education (GRaCE)

DEFF Research Database (Denmark)

Turner, Sandra; Eriksen, Jesper G; Trotter, Theresa

2015-01-01

Representatives from countries and regions world-wide who have implemented modern competency-based radiation- or clinical oncology curricula for training medical specialists, met to determine the feasibility and value of an ongoing international collaboration. In this forum, educational leaders...... with similar goals, would provide a valuable vehicle to ensure training program currency, through sharing of resources and expertise, and enhance high quality radiation oncology education. Potential projects for the Global Radiation Oncology Collaboration in Education (GRaCE) were agreed upon...

How well are the climate indices related to the GRACE-observed total water storage changes in China?

Science.gov (United States)

Devaraju, B.; Vishwakarma, B.; Sneeuw, N. J.

2017-12-01

The fresh water availability over land masses is changing rapidly under the influence of climate change and human intervention. In order to manage our water resources and plan for a better future, we need to demarcate the role of climate change. The total water storage change in a region can be obtained from the GRACE satellite mission. On the other hand, many climate change indicators, for example ENSO, are derived from sea surface temperature. In this contribution we investigate the relationship between the total water storage change over China with the climate indices using statistical time-series decomposition techniques, such as Seasonal and Trend decomposition using Loess (STL), Principal Component Analysis (PCA) and Canonical Correlation Analysis (CCA). The anomalies in climate variables, such as sea surface temperature, are responsible for anomalous precipitation and thus an anomalous total water storage change over land. Therefore, it is imperative that we use a GRACE product that can capture anomalous water storage changes with unprecedented accuracy. Since filtering decreases the sensitivity of GRACE products substantially, we use the data-driven method of deviation for recovering the signal lost due to filtering. To this end, we are able to obtain the spatial fingerprint of individual climate index on total water storage change observed over China.

The characteristics of soda metasomatite type uranium mineralization for proterozoic strata in the central-southern part of Kang-Dian earth's axis

International Nuclear Information System (INIS)

Qian Farong

1995-12-01

The uranium mineralization for Proterozoic strata in the central-southern part of Kang-Dian earth's axis can be divided into four typy (sandstone, soda metasomatite, proterozoic epimetamorphics and quartzite). The soda metasomatite type is the dominant type of uranium mineralization and has the prospecting potential in the area. The characteristics of this type uranium mineralization and the problems of metallogenesis are discussed. Soda metasomatite type uranium mineralization is controlled by soda metasomatite and structure. Uranium exists mainly in the forms of minerals (pitchblende, uranate). Its cell parameter is high and oxygenated coefficient is low, belonging to moderate-low temperature hydrothermal origin. The metallogenetic materials originated from deep-seated crust and country rocks. The metallogenetic solution includes a great quantity of atmospheric water, besides hydrothermal solution from deep-seated crust. The metallogene underwent the two stages i.e. Jinnin and Chengjiang. (4 tabs., 3 figs.)

Towards Improved Snow Water Equivalent Estimation via GRACE Assimilation

Science.gov (United States)

Forman, Bart; Reichle, Rofl; Rodell, Matt

2011-01-01

Passive microwave (e.g. AMSR-E) and visible spectrum (e.g. MODIS) measurements of snow states have been used in conjunction with land surface models to better characterize snow pack states, most notably snow water equivalent (SWE). However, both types of measurements have limitations. AMSR-E, for example, suffers a loss of information in deep/wet snow packs. Similarly, MODIS suffers a loss of temporal correlation information beyond the initial accumulation and final ablation phases of the snow season. Gravimetric measurements, on the other hand, do not suffer from these limitations. In this study, gravimetric measurements from the Gravity Recovery and Climate Experiment (GRACE) mission are used in a land surface model data assimilation (DA) framework to better characterize SWE in the Mackenzie River basin located in northern Canada. Comparisons are made against independent, ground-based SWE observations, state-of-the-art modeled SWE estimates, and independent, ground-based river discharge observations. Preliminary results suggest improved SWE estimates, including improved timing of the subsequent ablation and runoff of the snow pack. Additionally, use of the DA procedure can add vertical and horizontal resolution to the coarse-scale GRACE measurements as well as effectively downscale the measurements in time. Such findings offer the potential for better understanding of the hydrologic cycle in snow-dominated basins located in remote regions of the globe where ground-based observation collection if difficult, if not impossible. This information could ultimately lead to improved freshwater resource management in communities dependent on snow melt as well as a reduction in the uncertainty of river discharge into the Arctic Ocean.

Assessing sequential data assimilation techniques for integrating GRACE data into a hydrological model

KAUST Repository

Khaki, M.

2017-07-06

The time-variable terrestrial water storage (TWS) products from the Gravity Recovery And Climate Experiment (GRACE) have been increasingly used in recent years to improve the simulation of hydrological models by applying data assimilation techniques. In this study, for the first time, we assess the performance of the most popular data assimilation sequential techniques for integrating GRACE TWS into the World-Wide Water Resources Assessment (W3RA) model. We implement and test stochastic and deterministic ensemble-based Kalman filters (EnKF), as well as Particle filters (PF) using two different resampling approaches of Multinomial Resampling and Systematic Resampling. These choices provide various opportunities for weighting observations and model simulations during the assimilation and also accounting for error distributions. Particularly, the deterministic EnKF is tested to avoid perturbing observations before assimilation (that is the case in an ordinary EnKF). Gaussian-based random updates in the EnKF approaches likely do not fully represent the statistical properties of the model simulations and TWS observations. Therefore, the fully non-Gaussian PF is also applied to estimate more realistic updates. Monthly GRACE TWS are assimilated into W3RA covering the entire Australia. To evaluate the filters performances and analyze their impact on model simulations, their estimates are validated by independent in-situ measurements. Our results indicate that all implemented filters improve the estimation of water storage simulations of W3RA. The best results are obtained using two versions of deterministic EnKF, i.e. the Square Root Analysis (SQRA) scheme and the Ensemble Square Root Filter (EnSRF), respectively improving the model groundwater estimations errors by 34% and 31% compared to a model run without assimilation. Applying the PF along with Systematic Resampling successfully decreases the model estimation error by 23%.

Measuring Zonal Transport Variability of the Antarctic Circumpolar Current Using GRACE Ocean Bottom Pressure

Science.gov (United States)

Makowski, J.; Chambers, D. P.; Bonin, J. A.

2012-12-01

Previous studies have suggested that ocean bottom pressure (OBP) can be used to measure the transport variability of the Antarctic Circumpolar Current (ACC). Using OBP data from the JPL ECCO model and the Gravity Recovery and Climate Experiment (GRACE), we examine the zonal transport variability of the ACC integrated between the major fronts between 2003-2010. The JPL ECCO data are used to determine average front positions for the time period studies, as well as where transport is mainly zonal. Statistical analysis will be conducted to determine the uncertainty of the GRACE observations using a simulated data set. We will also begin looking at low frequency changes and how coherent transport variability is from region to region of the ACC. Correlations with bottom pressure south of the ACC and the average basin transports will also be calculated to determine the probability of using bottom pressure south of the ACC as a means for describing the ACC dynamics and transport.

Evaluation of Release-05 GRACE time-variable gravity coefficients over the ocean

Directory of Open Access Journals (Sweden)

D. P. Chambers

2012-10-01

Full Text Available The latest release of GRACE (Gravity Recovery and Climate Experiment gravity field coefficients (Release-05, or RL05 are evaluated for ocean applications. Data have been processed using the current methodology for Release-04 (RL04 coefficients, and have been compared to output from two different ocean models. Results indicate that RL05 data from the three Science Data Centers – the Center for Space Research (CSR, GeoForschungsZentrum (GFZ, and Jet Propulsion Laboratory (JPL – are more consistent among themselves than the previous RL04 data. Moreover, the variance of residuals with the output of an ocean model is 50–60% lower for RL05 data than for RL04 data. A more optimized destriping algorithm is also tested, which improves the results slightly. By comparing the GRACE maps with two different ocean models, we can better estimate the uncertainty in the RL05 maps. We find the standard error to be about 1 cm (equivalent water thickness in the low- and mid-latitudes, and between 1.5 and 2 cm in the polar and subpolar oceans, which is comparable to estimated uncertainty for the output from the ocean models.

Incorporation of GRACE Data into a Bayesian Model for Groundwater Drought Monitoring

Science.gov (United States)

Slinski, K.; Hogue, T. S.; McCray, J. E.; Porter, A.

2015-12-01

Groundwater drought, defined as the sustained occurrence of below average availability of groundwater, is marked by below average water levels in aquifers and reduced flows to groundwater-fed rivers and wetlands. The impact of groundwater drought on ecosystems, agriculture, municipal water supply, and the energy sector is an increasingly important global issue. However, current drought monitors heavily rely on precipitation and vegetative stress indices to characterize the timing, duration, and severity of drought events. The paucity of in situ observations of aquifer levels is a substantial obstacle to the development of systems to monitor groundwater drought in drought-prone areas, particularly in developing countries. Observations from the NASA/German Space Agency's Gravity Recovery and Climate Experiment (GRACE) have been used to estimate changes in groundwater storage over areas with sparse point measurements. This study incorporates GRACE total water storage observations into a Bayesian framework to assess the performance of a probabilistic model for monitoring groundwater drought based on remote sensing data. Overall, it is hoped that these methods will improve global drought preparedness and risk reduction by providing information on groundwater drought necessary to manage its impacts on ecosystems, as well as on the agricultural, municipal, and energy sectors.

Measuring Two Decades of Ice Mass Loss using GRACE and SLR

Science.gov (United States)

Bonin, J. A.; Chambers, D. P.

2016-12-01

We use Satellite Laser Ranging (SLR) to extend the time series of ice mass change back in time to 1994. The SLR series is of far lesser spatial resolution than GRACE, so we apply a constrained inversion technique to better localize the signal. We approximate the likely errors due to SLR's measurement errors combined with the inversion errors from using a low-resolution series, then estimate the interannual mass change over Greenland and Antarctica.

Land Water Storage within the Congo Basin Inferred from GRACE Satellite Gravity Data

Science.gov (United States)

Crowley, John W.; Mitrovica, Jerry X.; Bailey, Richard C.; Tamisiea, Mark E.; Davis, James L.

2006-01-01

GRACE satellite gravity data is used to estimate terrestrial (surface plus ground) water storage within the Congo Basin in Africa for the period of April, 2002 - May, 2006. These estimates exhibit significant seasonal (30 +/- 6 mm of equivalent water thickness) and long-term trends, the latter yielding a total loss of approximately 280 km(exp 3) of water over the 50-month span of data. We also combine GRACE and precipitation data set (CMAP, TRMM) to explore the relative contributions of the source term to the seasonal hydrological balance within the Congo Basin. We find that the seasonal water storage tends to saturate for anomalies greater than 30-44 mm of equivalent water thickness. Furthermore, precipitation contributed roughly three times the peak water storage after anomalously rainy seasons, in early 2003 and 2005, implying an approximately 60-70% loss from runoff and evapotranspiration. Finally, a comparison of residual land water storage (monthly estimates minus best-fitting trends) in the Congo and Amazon Basins shows an anticorrelation, in agreement with the 'see-saw' variability inferred by others from runoff data.

Eternal extended inflation and graceful exit from old inflation without Jordan-Brans-Dicke

Science.gov (United States)

Linde, Andrei

1990-10-01

Recently a possible solution to the graceful exit problem of the old inflation was proposed in the context of the Jordan-Brans-Dicke theory (extended inflation). In this paper we will argue that inflation in this theory occurs in a most natural way if it starts near the Planck density, as in the standard version of chaotic inflation. With most natural initial conditions, the inflationary universe in the JBD theory enters the stage of permanent reproduction of new inflationary domains (eternal extended inflation). In order to realize the extended inflation scenario at least two classical scalar fields driving inflation are necessary, as distinct from the simplest versions of new and chaotic inflation. It is shown that in the theory of two scalar fields one can solve the graceful exit problem even without modifying the Einstein gravity theory, due to the possibility that the decay rate of the false rate vacuum in old inflation depends on the value of the second scalar field and hence on time. Address after 1 September 1990: Physics Department, Stanford University, Varian Building, Stanford, CA 94305, USA.

Graceful, harmonious and magic type labelings relations and techniques

CERN Document Server

López, Susana C

2017-01-01

Aimed toward upper undergraduate and graduate students in mathematics, this book examines the foremost forms of graph labelings including magic, harmonious, and graceful labelings. An overview of basic graph theory concepts and notation is provided along with the origins of graph labeling. Common methods and techniques are presented introducing readers to links between graph labels. A variety of useful techniques are presented to analyze and understand properties of graph labelings. The classical results integrated with new techniques, complete proofs, numerous exercises, and a variety of open problems, will provide readers with a solid understanding of graph labelings.

Seasonal Gravity Field Variations from GRACE and Hydrological Models

DEFF Research Database (Denmark)

Andersen, Ole Baltazar; Hinderer, Jacques; Lemoine, Frank G.

2004-01-01

. Four global hydrological models covering the same period in 2002–2003 as the GRACE observations were investigated to for their mutual consistency in estimates of annual variation in terrestrial water storage and related temporal changes in gravity field. The hydrological models differ by a maximum of 2...... µGal or nearly 5 cm equivalent water storage in selected regions. Integrated over all land masses the standard deviation among the annual signal from the four hydrological models are 0.6 µGal equivalent to around 1.4 cm in equivalent water layer thickness. The estimated accuracy of the annual...

Managing emotional fallout. Parting remarks from America's top psychiatrist. Interview by Diane Coutu.

Science.gov (United States)

Hyman, Steven E

2002-02-01

Last fall, the United States was brutally thrust into a new and dangerous world. As the twin towers of the World Trade Center collapsed and the Pentagon burned, the horrible reality of terrorism seared the American consciousness. It touched more than the victims and their families; everyone who sat transfixed before the horrific images on TV lived through the trauma. In a sense, we were all eyewitnesses, and we must all cope with feelings of anger, stress, and anxiety. That poses a huge immediate challenge for business, because it is largely in the workplace--where we spend so many of our waking hours--that we will confront these emotions. And many companies have risen to the challenge, establishing new guidelines for processing mail in light of anthrax fears and organizing stress reduction programs for employees. While the logic of taking such action is incontestable, it raises a much larger question: What responsibility does a company bear for the mental well-being of its work-force? If companies help employees deal with depression and anxiety in the wake of terrorist acts, doesn't that put mental health care on the business agenda? To answer these questions, HBR senior editor Diane Coutu talked with Dr. Steven Hyman, the former director of the National Institute for Mental Health. In this interview, he discusses the implications of coping with tragedy, the resilience of individuals, and the treatment of mental illness. And he suggests that September 11, 2001, may come to be seen as a tipping point--the moment when managers started to think about dealing with mental health issues on a regular basis.

Hydrology signal from GRACE gravity data in the Nelson River basin, Canada: a comparison of two approaches

Science.gov (United States)

Li, Tanghua; Wu, Patrick; Wang, Hansheng; Jia, Lulu; Steffen, Holger

2018-03-01

The Gravity Recovery and Climate Experiment (GRACE) satellite mission measures the combined gravity signal of several overlapping processes. A common approach to separate the hydrological signal in previous ice-covered regions is to apply numerical models to simulate the glacial isostatic adjustment (GIA) signals related to the vanished ice load and then remove them from the observed GRACE data. However, the results of this method are strongly affected by the uncertainties of the ice and viscosity models of GIA. To avoid this, Wang et al. (Nat Geosci 6(1):38-42, 2013. https://doi.org/10.1038/NGEO1652; Geodesy Geodyn 6(4):267-273, 2015) followed the theory of Wahr et al. (Geophys Res Lett 22(8):977-980, 1995) and isolated water storage changes from GRACE in North America and Scandinavia with the help of Global Positioning System (GPS) data. Lambert et al. (Postglacial rebound and total water storage variations in the Nelson River drainage basin: a gravity GPS Study, Geological Survey of Canada Open File, 7317, 2013a, Geophys Res Lett 40(23):6118-6122, https://doi.org/10.1002/2013GL057973, 2013b) did a similar study for the Nelson River basin in North America but applying GPS and absolute gravity measurements. However, the results of the two studies in the Nelson River basin differ largely, especially for the magnitude of the hydrology signal which differs about 35%. Through detailed comparison and analysis of the input data, data post-processing techniques, methods and results of these two works, we find that the different GRACE data post-processing techniques may lead to this difference. Also the GRACE input has a larger effect on the hydrology signal amplitude than the GPS input in the Nelson River basin due to the relatively small uplift signal in this region. Meanwhile, the influence of the value of α , which represents the ratio between GIA-induced uplift rate and GIA-induced gravity-rate-of-change (before the correction for surface uplift), is more obvious in

Improvement of the GRACE star camera data based on the revision of the combination method

Science.gov (United States)

Bandikova, Tamara; Flury, Jakob

2014-11-01

The new release of the sensor and instrument data (Level-1B release 02) of the Gravity Recovery and Climate Experiment (GRACE) had a substantial impact on the improvement of the overall accuracy of the gravity field models. This has implied that improvements on the sensor data level can still significantly contribute to arriving closer to the GRACE baseline accuracy. The recent analysis of the GRACE star camera data (SCA1B RL02) revealed their unexpectedly higher noise. As the star camera (SCA) data are essential for the processing of the K-band ranging data and the accelerometer data, thorough investigation of the data set was needed. We fully reexamined the SCA data processing from Level-1A to Level-1B with focus on the combination method of the data delivered by the two SCA heads. In the first step, we produced and compared our own combined attitude solution by applying two different combination methods on the SCA Level-1A data. The first method introduces the information about the anisotropic accuracy of the star camera measurement in terms of a weighing matrix. This method was applied in the official processing as well. The alternative method merges only the well determined SCA boresight directions. This method was implemented on the GRACE SCA data for the first time. Both methods were expected to provide optimal solution characteristic by the full accuracy about all three axes, which was confirmed. In the second step, we analyzed the differences between the official SCA1B RL02 data generated by the Jet Propulsion Laboratory (JPL) and our solution. SCA1B RL02 contains systematically higher noise of about a factor 3-4. The data analysis revealed that the reason is the incorrect implementation of algorithms in the JPL processing routines. After correct implementation of the combination method, significant improvement within the whole spectrum was achieved. Based on these results, the official reprocessing of the SCA data is suggested, as the SCA attitude data

Time Changes of the European Gravity Field from GRACE: A Comparison with Ground Measurements from Superconducting Gravimeters and with Hydrology Model Predictions

Science.gov (United States)

Hinderer, J.; Lemoine, Frank G.; Crossley, D.; Boy, J.-P.

2004-01-01

We investigate the time-variable gravity changes in Europe retrieved from the initial GRACE monthly solutions spanning a 18 month duration from April 2002 to October 2003. Gravity anomaly maps are retrieved in Central Europe from the monthly satellite solutions we compare the fields according to various truncation levels (typically between degree 10 and 20) of the initial fields (expressed in spherical harmonics to degree 120). For these different degrees, an empirical orthogonal function (EOF) decomposition of the time-variable gravity field leads us to its main spatial and temporal characteristics. We show that the dominant signal is found to be annual with an amplitude and a phase both in agreement with predictions in Europe modeled using snow and soil-moisture variations from recent hydrology models. We compare these GRACE gravity field changes to surface gravity observations from 6 superconducting gravimeters of the GGP (Global Geodynamics Project) European sub-network, with a special attention to loading corrections. Initial results suggest that all 3 data sets (GRACE, hydrology and GGP) are responding to annual changes in near-surface water in Europe of a few microGal (at length scales of approx.1000 km) that show a high value in winter and a summer minimum. We also point out that the GRACE gravity field evolution seems to indicate that there is a trend in gravity between summer 2002 and summer 2003 which can be related to the 2003 heatwave in Europe and its hydrological consequences (drought). Despite the limited time span of our analysis and the uncertainties in retrieving a regional solution from the network of gravimeters, the calibration and validation aspects of the GRACE data processing based on the annual hydrology cycle in Europe are in progress.

Assessing Drought Impacts on Water Storage using GRACE Satellites and Regional Groundwater Modeling in the Central Valley of California

Science.gov (United States)

Scanlon, B. R.; Zhang, Z.; Save, H.; Faunt, C. C.; Dettinger, M. D.

2015-12-01

Increasing concerns about drought impacts on water resources in California underscores the need to better understand effects of drought on water storage and coping strategies. Here we use a new GRACE mascons solution with high spatial resolution (1 degree) developed at the Univ. of Texas Center for Space Research (CSR) and output from the most recent regional groundwater model developed by the U.S. Geological Survey to evaluate changes in water storage in response to recent droughts. We also extend the analysis of drought impacts on water storage back to the 1980s using modeling and monitoring data. The drought has been intensifying since 2012 with almost 50% of the state and 100% of the Central Valley under exceptional drought in 2015. Total water storage from GRACE data declined sharply during the current drought, similar to the rate of depletion during the previous drought in 2007 - 2009. However, only 45% average recovery between the two droughts results in a much greater cumulative impact of both droughts. The CSR GRACE Mascons data offer unprecedented spatial resolution with no leakage to the oceans and no requirement for signal restoration. Snow and reservoir storage declines contribute to the total water storage depletion estimated by GRACE with the residuals attributed to groundwater storage. Rates of groundwater storage depletion are consistent with the results of regional groundwater modeling in the Central Valley. Traditional approaches to coping with these climate extremes has focused on surface water reservoir storage; however, increasing conjunctive use of surface water and groundwater and storing excess water from wet periods in depleted aquifers is increasing in the Central Valley.

Complete mitogenome of the Graceful Shark Carcharhinus amblyrhynchoides (Carcharhiniformes: Carcharhinidae).

Science.gov (United States)

Feutry, Pierre; Pillans, Richard D; Kyne, Peter M; Chen, Xiao

2016-01-01

In this manuscript we describe the first complete mitochondrial sequence for the Near Threatened Graceful Shark Carcharhinus amblyrhynchoides. It is 16,705 bp in length, consists of two rRNA genes, 22 tRNA genes, 13 protein-coding genes and one control region with the typical gene arrangement pattern and translate orientation in vertebrates. The overall base composition is 31.4% A, 25.1% C, 13.2% G and 30.3% T. The shortest tRNA-Ser2 cannot fold into a clover-leaf secondary structure due to the lack of the dihydrouridine arm.

Using ocean bottom pressure from the gravity recovery and climate experiment (GRACE) to estimate transport variability in the southern Indian Ocean

Science.gov (United States)

Makowski, Jessica K.; Chambers, Don P.; Bonin, Jennifer A.

2015-06-01

Previous studies have suggested that ocean bottom pressure (OBP) from the Gravity Recovery and Climate Experiment (GRACE) can be used to measure the depth-averaged, or barotropic, transport variability of the Antarctic Circumpolar Current (ACC). Here, we use GRACE OBP observations to calculate transport variability in a region of the southern Indian Ocean encompassing the major fronts of the ACC. We use a statistical analysis of a simulated GRACE-like data set to determine the uncertainty of the estimated transport for the 2003.0-2013.0 time period. We find that when the transport is averaged over 60° of longitude, the uncertainty (one standard error) is close to 1 Sv (1 Sv = 106 m3 s-1) for low-pass filtered transport, which is significantly smaller than the signal and lower than previous studies have found. The interannual variability is correlated with the Southern Annual mode (SAM) (0.61), but more highly correlated with circumpolar zonally averaged winds between 45°S and 65°S (0.88). GRACE transport reflects significant changes in transport between 2007 and 2009 that is observed in the zonal wind variations but not in the SAM index. We also find a statistically significant trend in transport (-1.0 ± 0.4 Sv yr-1, 90% confidence) that is correlated with a local deceleration in zonal winds related to an asymmetry in the SAM on multidecadal periods.

Improving groundwater storage and soil moisture estimates by assimilating GRACE, SMOS, and SMAP data into CABLE using ensemble Kalman batch smoother and particle batch smoother frameworks

Science.gov (United States)

Han, S. C.; Tangdamrongsub, N.; Yeo, I. Y.; Dong, J.

2017-12-01

Soil moisture and groundwater storage are important information for comprehensive understanding of the climate system and accurate assessment of the regional/global water resources. It is possible to derive the water storage from land surface models but the outputs are commonly biased by inaccurate forcing data, inefficacious model physics, and improper model parameter calibration. To mitigate the model uncertainty, the observation (e.g., from remote sensing as well as ground in-situ data) are often integrated into the models via data assimilation (DA). This study aims to improve the estimation of soil moisture and groundwater storage by simultaneously assimilating satellite observations from the Gravity Recovery And Climate Experiment (GRACE), the Soil Moisture Ocean Salinity (SMOS), and the Soil Moisture Active Passive (SMAP) into the Community Atmosphere Biosphere Land Exchange (CABLE) land surface model using the ensemble Kalman batch smoother (EnBS) and particle batch smoother (PBS) frameworks. The uncertainty of GRACE observation is obtained rigorously from the full error variance-covariance matrix of the GRACE data product. This method demonstrates the use of a realistic representative of GRACE uncertainty, which is spatially correlated in nature, leads to a higher accuracy of water storage computation. Additionally, the comparison between EnBS and PBS results is discussed to understand the filter's performance, limitation, and suitability. The joint DA is demonstrated in the Goulburn catchment, South-East Australia, where diverse ground observations (surface soil moisture, root-zone soil moisture, and groundwater level) are available for evaluation of our DA results. Preliminary results show that both smoothers provide significant improvement of surface soil moisture and groundwater storage estimates. Importantly, our developed DA scheme disaggregates the catchment-scale GRACE information into finer vertical and spatial scales ( 25 km). We present an

Mass-induced sea level variations in the Red Sea from steric-corrected altimetry, GRACE, in-situ bottom pressure records, and hydrographic observations

Science.gov (United States)

Feng, Wei; Lemoine, Jean-Michel; Zhong, Min; Xu, Houze

2014-05-01

An annual amplitude of ~18 cm mass-induced sea level variations (SLV) in the Red Sea is detected from steric-corrected altimetry and the Gravity Recovery and Climate Experiment (GRACE) satellites from 2003 to 2011, which dominates the mean sea level in the region. Seawater mass variations here generally reach maximum in late January/early February. The steric component of SLV calculated from oceanographic temperature and salinity data is relatively small and peaks about seven months later than mass variations. The phase difference between the steric SLV and the mass-induced SLV indicates that when the Red Sea gains the mass from inflow water in winter, the steric SLV fall, and vice versa in summer. In-situ bottom pressure records in the eastern coast of the Red Sea validate the high mass variability observed by steric-corrected altimetry and GRACE. Furthermore, we compare the horizontal water mass flux in the Red Sea from steric-corrected altimetry and GRACE with that estimated from hydrographic observations.

Monitoring mass changes in the Volta River basin using GRACE satellite gravity and TRMM precipitation

Directory of Open Access Journals (Sweden)

Vagner G. Ferreira

Full Text Available GRACE satellite gravity data was used to estimate mass changes within the Volta River basin in West African for the period of January, 2005 to December, 2010. We also used the precipitation data from the Tropical Rainfall Measurement Mission (TRMM to determine relative contributions source to the seasonal hydrological balance within the Volta River basin. We found out that the seasonal mass change tends to be detected by GRACE for periods from 1 month in the south to 4 months in the north of the basin after the rainfall events. The results suggested a significant gain in water storage in the basin at reference epoch 2007.5 and a dominant annual cycle for the period under consideration for both in the mass changes and rainfall time series. However, there was a low correlation between mass changes and rainfall implying that there must be other processes which cause mass changes without rainfall in the upstream of the Volta River basin.

Interannual variability in water storage over 2003-2008 in the Amazon Basin from GRACE space gravimetry, in situ river level and precipitation data

OpenAIRE

Xavier , L.; Becker , M.; Cazenave , A.; Longuevergne , L.; Llovel , W.; Rotunno Filho , Otto Correa

2012-01-01

International audience; We investigate the interannual variability over 2003-2008 of different hydrological parameters in the Amazon river basin: (1) vertically-integrated water storage from the GRACE space gravimetry mission, (2) surface water level of the Amazon River and its tributaries from in situ gauge stations, and (3) precipitation. We analyze the spatio-temporal evolution of total water storage from GRACE and in situ river level along the Amazon River and its main tributaries and not...

Graceful Failure, Engineering, and Planning for Extremes: The Engineering for Climate Extremes Partnership (ECEP)

Science.gov (United States)

Bruyere, C. L.; Tye, M. R.; Holland, G. J.; Done, J.

2015-12-01

Graceful failure acknowledges that all systems will fail at some level and incorporates the potential for failure as a key component of engineering design, community planning, and the associated research and development. This is a fundamental component of the ECEP, an interdisciplinary partnership bringing together scientific, engineering, cultural, business and government expertise to develop robust, well-communicated predictions and advice on the impacts of weather and climate extremes in support of decision-making. A feature of the partnership is the manner in which basic and applied research and development is conducted in direct collaboration with the end user. A major ECEP focus is the Global Risk and Resilience Toolbox (GRRT) that is aimed at developing public-domain, risk-modeling and response data and planning system in support of engineering design, and community planning and adaptation activities. In this presentation I will outline the overall ECEP and GRIP activities, and expand on the 'graceful failure' concept. Specific examples for direct assessment and prediction of hurricane impacts and damage potential will be included.

Improving Soil Moisture Estimation through the Joint Assimilation of SMOS and GRACE Satellite Observations

Science.gov (United States)

Girotto, Manuela

2018-01-01

Observations from recent soil moisture dedicated missions (e.g. SMOS or SMAP) have been used in innovative data assimilation studies to provide global high spatial (i.e., approximately10-40 km) and temporal resolution (i.e., daily) soil moisture profile estimates from microwave brightness temperature observations. These missions are only sensitive to near-surface soil moisture 0-5 cm). In contrast, the Gravity Recovery and Climate Experiment (GRACE) mission provides accurate measurements of the entire vertically integrated terrestrial water storage (TWS) column but, it is characterized by low spatial (i.e., 150,000 km2) and temporal (i.e., monthly) resolutions. Data assimilation studies have shown that GRACE-TWS primarily affects (in absolute terms) deeper moisture storages (i.e., groundwater). In this presentation I will review benefits and drawbacks associated to the assimilation of both types of observations. In particular, I will illustrate the benefits and drawbacks of their joint assimilation for the purpose of improving the entire profile of soil moisture (i.e., surface and deeper water storages).

Results and Error Estimates from GRACE Forward Modeling over Greenland, Canada, and Alaska

Science.gov (United States)

Bonin, J. A.; Chambers, D. P.

2012-12-01

Forward modeling using a weighted least squares technique allows GRACE information to be projected onto a pre-determined collection of local basins. This decreases the impact of spatial leakage, allowing estimates of mass change to be better localized. The technique is especially valuable where models of current-day mass change are poor, such as over Greenland and Antarctica. However, the accuracy of the forward model technique has not been determined, nor is it known how the distribution of the local basins affects the results. We use a "truth" model composed of hydrology and ice-melt slopes as an example case, to estimate the uncertainties of this forward modeling method and expose those design parameters which may result in an incorrect high-resolution mass distribution. We then apply these optimal parameters in a forward model estimate created from RL05 GRACE data. We compare the resulting mass slopes with the expected systematic errors from the simulation, as well as GIA and basic trend-fitting uncertainties. We also consider whether specific regions (such as Ellesmere Island and Baffin Island) can be estimated reliably using our optimal basin layout.

Modes of Arctic Ocean Change from GRACE, ICESat and the PIOMAS and ECCO2 Models of the Arctic Ocean

Science.gov (United States)

Peralta Ferriz, C.; Morison, J. H.; Bonin, J. A.; Chambers, D. P.; Kwok, R.; Zhang, J.

2012-12-01

EOF analysis of month-to-month variations in GRACE derived Arctic Ocean bottom pressure (OBP) with trend and seasonal variation removed yield three dominant modes. The first mode is a basin wide variation in mass associated with high atmospheric pressure (SLP) over Scandinavia mainly in winter. The second mode is a shift of mass from the central Arctic Ocean to the Siberian shelves due to low pressure over the basins, associated with the Arctic Oscillation. The third mode is a shift in mass between the Eastern and Western Siberian shelves, related to strength of the Beaufort High mainly in summer, and to eastward alongshore winds on the Barents Sea in winter. The PIOMAS and ECCO2 modeled OBP show fair agreement with the form of these modes and provide context in terms of variations in sea surface height SSH. Comparing GRACE OBP from 2007 to 2011 with GRACE OBP from 2002 to 2006 reveals a rising trend over most of the Arctic Ocean but declines in the Kara Sea region and summer East Siberian Sea. ECCO2 bears a faint resemblance to the observed OBP change but appears to be biased negatively. In contrast, PIOMAS SSH and ECCO2 especially, show changes between the two periods that are muted but similar to ICESat dynamic ocean topography and GRACE-ICESat freshwater trends from 2005 through 2008 [Morison et al., 2012] with a rising DOT and freshening in the Beaufort Sea and a trough with decreased freshwater on the Russian side of the Arctic Ocean. Morison, J., R. Kwok, C. Peralta-Ferriz, M. Alkire, I. Rigor, R. Andersen, and M. Steele (2012), Changing Arctic Ocean freshwater pathways, Nature, 481(7379), 66-70.

Along-track geopotential difference and deflection of the vertical from grace range rate : Use of GEOGRACE

NARCIS (Netherlands)

Tangdamrongsub, N.; Hwang, Cheinway

2016-01-01

We present a theory and numerical algorithm to directly determine the time-varying along-track geopotential difference and deflection of the vertical at the Gravity Recovery and Climate Experiment (GRACE) satellite altitude. The determination was implemented using the GEOGRACE computer program

Global analysis of approaches for deriving total water storage changes from GRACE satellites and implications for groundwater storage change estimation

Science.gov (United States)

Long, D.; Scanlon, B. R.; Longuevergne, L.; Chen, X.

2015-12-01

Increasing interest in use of GRACE satellites and a variety of new products to monitor changes in total water storage (TWS) underscores the need to assess the reliability of output from different products. The objective of this study was to assess skills and uncertainties of different approaches for processing GRACE data to restore signal losses caused by spatial filtering based on analysis of 1°×1° grid scale data and basin scale data in 60 river basins globally. Results indicate that scaling factors from six land surface models (LSMs), including four models from GLDAS-1 (Noah 2.7, Mosaic, VIC, and CLM 2.0), CLM 4.0, and WGHM, are similar over most humid, sub-humid, and high-latitude regions but can differ by up to 100% over arid and semi-arid basins and areas with intensive irrigation. Large differences in TWS anomalies from three processing approaches (scaling factor, additive, and multiplicative corrections) were found in arid and semi-arid regions, areas with intensive irrigation, and relatively small basins (e.g., ≤ 200,000 km2). Furthermore, TWS anomaly products from gridded data with CLM4.0 scaling factors and the additive correction approach more closely agree with WGHM output than the multiplicative correction approach. Estimation of groundwater storage changes using GRACE satellites requires caution in selecting an appropriate approach for restoring TWS changes. A priori ground-based data used in forward modeling can provide a powerful tool for explaining the distribution of signal gains or losses caused by low-pass filtering in specific regions of interest and should be very useful for more reliable estimation of groundwater storage changes using GRACE satellites.

Deriving Scaling Factors Using a Global Hydrological Model to Restore GRACE Total Water Storage Changes for China's Yangtze River Basin

Science.gov (United States)

Long, Di; Yang, Yuting; Yoshihide, Wada; Hong, Yang; Liang, Wei; Chen, Yaning; Yong, Bin; Hou, Aizhong; Wei, Jiangfeng; Chen, Lu

2015-01-01

This study used a global hydrological model (GHM), PCR-GLOBWB, which simulates surface water storage changes, natural and human induced groundwater storage changes, and the interactions between surface water and subsurface water, to generate scaling factors by mimicking low-pass filtering of GRACE signals. Signal losses in GRACE data were subsequently restored by the scaling factors from PCR-GLOBWB. Results indicate greater spatial heterogeneity in scaling factor from PCR-GLOBWB and CLM4.0 than that from GLDAS-1 Noah due to comprehensive simulation of surface and subsurface water storage changes for PCR-GLOBWB and CLM4.0. Filtered GRACE total water storage (TWS) changes applied with PCR-GLOBWB scaling factors show closer agreement with water budget estimates of TWS changes than those with scaling factors from other land surface models (LSMs) in China's Yangtze River basin. Results of this study develop a further understanding of the behavior of scaling factors from different LSMs or GHMs over hydrologically complex basins, and could be valuable in providing more accurate TWS changes for hydrological applications (e.g., monitoring drought and groundwater storage depletion) over regions where human-induced interactions between surface water and subsurface water are intensive.

Comparison of precise orbit determination methods of zero-difference kinematic, dynamic and reduced-dynamic of GRACE-A satellite using SHORDE software

Science.gov (United States)

Li, Kai; Zhou, Xuhua; Guo, Nannan; Zhao, Gang; Xu, Kexin; Lei, Weiwei

2017-09-01

Zero-difference kinematic, dynamic and reduced-dynamic precise orbit determination (POD) are three methods to obtain the precise orbits of Low Earth Orbit satellites (LEOs) by using the on-board GPS observations. Comparing the differences between those methods have great significance to establish the mathematical model and is usefull for us to select a suitable method to determine the orbit of the satellite. Based on the zero-difference GPS carrier-phase measurements, Shanghai Astronomical Observatory (SHAO) has improved the early version of SHORDE and then developed it as an integrated software system, which can perform the POD of LEOs by using the above three methods. In order to introduce the function of the software, we take the Gravity Recovery And Climate Experiment (GRACE) on-board GPS observations in January 2008 as example, then we compute the corresponding orbits of GRACE by using the SHORDE software. In order to evaluate the accuracy, we compare the orbits with the precise orbits provided by Jet Propulsion Laboratory (JPL). The results show that: (1) If we use the dynamic POD method, and the force models are used to represent the non-conservative forces, the average accuracy of the GRACE orbit is 2.40cm, 3.91cm, 2.34cm and 5.17cm in radial (R), along-track (T), cross-track (N) and 3D directions respectively; If we use the accelerometer observation instead of non-conservative perturbation model, the average accuracy of the orbit is 1.82cm, 2.51cm, 3.48cm and 4.68cm in R, T, N and 3D directions respectively. The result shows that if we use accelerometer observation instead of the non-conservative perturbation model, the accuracy of orbit is better. (2) When we use the reduced-dynamic POD method to get the orbits, the average accuracy of the orbit is 0.80cm, 1.36cm, 2.38cm and 2.87cm in R, T, N and 3D directions respectively. This method is carried out by setting up the pseudo-stochastic pulses to absorb the errors of atmospheric drag and other

Application of the Regional Water Mass Variations from GRACE Satellite Gravimetry to Large-Scale Water Management in Africa

Directory of Open Access Journals (Sweden)

Guillaume Ramillien

2014-08-01

Full Text Available Time series of regional 2° × 2° Gravity Recovery and Climate Experiment (GRACE solutions of surface water mass change have been computed over Africa from 2003 to 2012 with a 10-day resolution by using a new regional approach. These regional maps are used to describe and quantify water mass change. The contribution of African hydrology to actual sea level rise is negative and small in magnitude (i.e., −0.1 mm/y of equivalent sea level (ESL mainly explained by the water retained in the Zambezi River basin. Analysis of the regional water mass maps is used to distinguish different zones of important water mass variations, with the exception of the dominant seasonal cycle of the African monsoon in the Sahel and Central Africa. The analysis of the regional solutions reveals the accumulation in the Okavango swamp and South Niger. It confirms the continuous depletion of water in the North Sahara aquifer at the rate of −2.3 km3/y, with a decrease in early 2008. Synergistic use of altimetry-based lake water volume with total water storage (TWS from GRACE permits a continuous monitoring of sub-surface water storage for large lake drainage areas. These different applications demonstrate the potential of the GRACE mission for the management of water resources at the regional scale.

Monitoring groundwater storage changes in the highly seasonal humid tropics: Validation of GRACE measurements in the Bengal Basin

Science.gov (United States)

Shamsudduha, M.; Taylor, R. G.; Longuevergne, L.

2012-02-01

Satellite monitoring of changes in terrestrial water storage provides invaluable information regarding the basin-scale dynamics of hydrological systems where ground-based records are limited. In the Bengal Basin of Bangladesh, we test the ability of satellite measurements under the Gravity Recovery and Climate Experiment (GRACE) to trace both the seasonality and trend in groundwater storage associated with intensive groundwater abstraction for dry-season irrigation and wet-season (monsoonal) recharge. We show that GRACE (CSR, GRGS) datasets of recent (2003 to 2007) groundwater storage changes (ΔGWS) correlate well (r = 0.77 to 0.93, p value CSR. Changes in surface water storage estimated from a network of 298 river gauging stations and soil-moisture derived from Land Surface Models explain 22% and 33% of ΔTWS, respectively. Groundwater depletion estimated from borehole hydrographs (-0.52 ± 0.30 km3 yr-1) is within the range of satellite-derived estimates (-0.44 to -2.04 km3 yr-1) that result from uncertainty associated with the simulation of soil moisture (CLM, NOAH, VIC) and GRACE signal-processing techniques. Recent (2003 to 2007) estimates of groundwater depletion are substantially greater than long-term (1985 to 2007) mean (-0.21 ± 0.03 km3 yr-1) and are explained primarily by substantial increases in groundwater abstraction for the dry-season irrigation and public water supplies over the last two decades.

GRACE gravity data help constraining seismic models of the 2004 Sumatran earthquake

Science.gov (United States)

Cambiotti, G.; Bordoni, A.; Sabadini, R.; Colli, L.

2011-10-01

The analysis of Gravity Recovery and Climate Experiment (GRACE) Level 2 data time series from the Center for Space Research (CSR) and GeoForschungsZentrum (GFZ) allows us to extract a new estimate of the co-seismic gravity signal due to the 2004 Sumatran earthquake. Owing to compressible self-gravitating Earth models, including sea level feedback in a new self-consistent way and designed to compute gravitational perturbations due to volume changes separately, we are able to prove that the asymmetry in the co-seismic gravity pattern, in which the north-eastern negative anomaly is twice as large as the south-western positive anomaly, is not due to the previously overestimated dilatation in the crust. The overestimate was due to a large dilatation localized at the fault discontinuity, the gravitational effect of which is compensated by an opposite contribution from topography due to the uplifted crust. After this localized dilatation is removed, we instead predict compression in the footwall and dilatation in the hanging wall. The overall anomaly is then mainly due to the additional gravitational effects of the ocean after water is displaced away from the uplifted crust, as first indicated by de Linage et al. (2009). We also detail the differences between compressible and incompressible material properties. By focusing on the most robust estimates from GRACE data, consisting of the peak-to-peak gravity anomaly and an asymmetry coefficient, that is given by the ratio of the negative gravity anomaly over the positive anomaly, we show that they are quite sensitive to seismic source depths and dip angles. This allows us to exploit space gravity data for the first time to help constraining centroid-momentum-tensor (CMT) source analyses of the 2004 Sumatran earthquake and to conclude that the seismic moment has been released mainly in the lower crust rather than the lithospheric mantle. Thus, GRACE data and CMT source analyses, as well as geodetic slip distributions aided

Predictive value of NT-proBNP for 30-day mortality in patients with non-ST-elevation acute coronary syndromes: a comparison with the GRACE and TIMI risk scores.

Science.gov (United States)

Schellings, Dirk Aam; Adiyaman, Ahmet; Dambrink, Jan-Henk E; Gosselink, At Marcel; Kedhi, Elvin; Roolvink, Vincent; Ottervanger, Jan Paul; Van't Hof, Arnoud Wj

2016-01-01

The biomarker N-terminal pro-brain natriuretic peptide (NT-proBNP) predicts outcome in patients with non-ST-elevation acute coronary syndromes (NSTE-ACS). Whether NT-proBNP has incremental prognostic value beyond established risk strategies is still questionable. To evaluate the predictive value of NT-proBNP for 30-day mortality over and beyond the Global Registry of Acute Coronary Events (GRACE) and Thrombolysis In Myocardial Infarction (TIMI) risk scores in patients with NSTE-ACS. Patients included in our ACS registry were candidates. NT-proBNP levels on admission were measured and the GRACE and TIMI risk scores were assessed. We compared the predictive value of NT-proBNP to both risk scores and evaluated whether NT-proBNP improves prognostication by using receiver operator curves and measures of discrimination improvement. A total of 1324 patients were included and 50 patients died during follow-up. On logistic regression analysis NT-proBNP and the GRACE risk score (but not the TIMI risk score) both independently predicted mortality at 30 days. The predictive value of NT-proBNP did not differ significantly compared to the GRACE risk score (area under the curve [AUC]) 0.85 vs 0.87 p =0.67) but was considerably higher in comparison to the TIMI risk score (AUC 0.60 p risk score by adding NT-proBNP did not improve prognostication: AUC 0.86 ( p =0.57), integrated discrimination improvement 0.04 ( p =0.003), net reclassification improvement 0.12 ( p =0.21). In patients with NSTE-ACS, NT-proBNP and the GRACE risk score (but not the TIMI risk score) both have good and comparable predictive value for 30-day mortality. However, incremental prognostic value of NT-proBNP beyond the GRACE risk score could not be demonstrated.

High resolution time-lapse gravity field from GRACE for hydrological modelling

DEFF Research Database (Denmark)

Krogh, Pernille Engelbredt

Calibration of large scale hydrological models have traditionally been performed using point observations, which are often sparsely distributed. The Gravity Recovery And Climate Experiment (GRACE) mission provides global remote sensing information about mass fluxes with unprecedented accuracy...... than for the mascon only solution, but later than the GLDAS/Noah TWS and the CNES/GRGS SH solutions. The deviations are 10–20 days. From this point of view, the tuning of hydrological models with KBRR data is certainly feasible, though highly time consuming and complicated at the moment. The method...

"Tugboat Annie:" nursing's hero of Pearl Harbor--Grace Lally (1897-1983).

Science.gov (United States)

Hawkins, J W; Matthews, I

1991-01-01

In 1991 we will mark the 50th anniversary of the Japanese attack on Pearl Harbor. Few nurses know that the Chief Nurse aboard the USS Solace, the only hospital ship in port on that fateful day, played a critical role in caring for the survivors. Grace Lally's calm, professional manner, along with her sensitivity to the needs of her patients, her 12 nurses, and the crew of the Solace made her a hero. This study is an investigation of her role on December 7, 1941, and her contributions as a career military nurse.

Pascal’s Wager and the dispute about the nature of Grace

Directory of Open Access Journals (Sweden)

Lech Gruszecki

2017-07-01

Full Text Available Pascal’s Wager is one of the most interesting and original arguments for the existence of God. It does not invoke advanced metaphysical concepts; instead, it employs the methods and concepts of probability calculus. Its argumentative power mainly rests on the appropriate interpretation of the determinants of human existence, which are taken to include our cognitive, moral and physical limitations. The article discusses different aspects of Pascal’s reasoning. In particular, it examines the wager in the context of Grace as something that Pascal himself believed in.

Antoine Ó Flatharta’s Elviad: from Grásta i Meiriceá to Grace in America

Directory of Open Access Journals (Sweden)

John L. Murphy

2006-03-01

Full Text Available Antoine Ó Flatharta bilingually charts media-saturated global impacts upon Galway’s Gaelic-speakers. His play in Irish,Grásta i Meiriceá (1990 features two young Irishmen who journey by bus on a pilgrimage to Elvis’ Graceland. In its 1993 English adaptation, Grace in America, the pair meets relatives who emigrated to 1940s Buffalo. Reading these plays by applying Seamus Deane’s “primordial nomination,” Edward Said’s “cartographical impulse,” Declan Kiberd’s “spiritual tourism,” and sociolinguistics, their relevance sharpens. In transforming Grásta into Grace, Ó Flatharta foreshadows his own shift into publishing in English. The fate of the play’s mutating Irish vernacular, as shown in Ó Flatharta’s drama, becomes less lamented than might be supposed. America, and English, represent liberation for his characters, in his work not only in English but –unexpectedly– in his other native language of Irish.

A comparison of the gravity field over Central Europe from superconducting gravimeters, GRACE and global hydrological models, using EOF analysis

Science.gov (United States)

Crossley, David; de Linage, Caroline; Hinderer, Jacques; Boy, Jean-Paul; Famiglietti, James

2012-05-01

We analyse data from seven superconducting gravimeter (SG) stations in Europe from 2002 to 2007 from the Global Geodynamics Project (GGP) and compare seasonal variations with data from GRACE and several global hydrological models - GLDAS, WGHM and ERA-Interim. Our technique is empirical orthogonal function (EOF) decomposition of the fields that allows for the inherent incompatibility of length scales between ground and satellite observations. GGP stations below the ground surface pose a problem because part of the attraction from soil moisture comes from above the gravimeter, and this gives rise to a complex (mixed) gravity response. The first principle component (PC) of the EOF decomposition is the main indicator for comparing the fields, although for some of the series it accounts for only about 50 per cent of the variance reduction. PCs for GRACE solutions RL04 from CSR and GFZ are filtered with a cosine taper (degrees 20-40) and a Gaussian window (350 km). Significant differences are evident between GRACE solutions from different groups and filters, though they all agree reasonably well with the global hydrological models for the predominantly seasonal signal. We estimate the first PC at 10-d sampling to be accurate to 1 μGal for GGP data, 1.5 μGal for GRACE data and 1 μGal between the three global hydrological models. Within these limits the CNES/GRGS solution and ground GGP data agree at the 79 per cent level, and better when the GGP solution is restricted to the three above-ground stations. The major limitation on the GGP side comes from the water mass distribution surrounding the underground instruments that leads to a complex gravity effect. To solve this we propose a method for correcting the SG residual gravity series for the effects of soil moisture above the station.

The use of gravimetric data from GRACE mission in the understanding of polar motion variations

Science.gov (United States)

Seoane, L.; Nastula, J.; Bizouard, C.; Gambis, D.

2009-08-01

Tesseral coefficients C21 and S21 derived from Gravity Recovery and Climate Experiment (GRACE) observations allow to compute the mass term of the polar-motion excitation function. This independent estimation can improve the geophysical models and, in addition, determine the unmodelled phenomena. In this paper, we intend to validate the polar motion excitation derived from GRACE's last release (GRACE Release 4) computed by different institutes: GeoForschungsZentrum (GFZ), Postdam, Germany; Center for Space Research (CSR), Austin, USA; Jet Propulsion Laboratory (JPL), Pasadena, USA, and the Groupe de Recherche en Géodésie Spatiale (GRGS), Toulouse, France. For this purpose, we compare these excitations functions first to the mass term obtained from observed Earth's rotation variations free of the motion term and, second, to the mass term estimated from geophysical fluids models. We confirm the large improvement of the CSR solution, and we show that the GRGS estimate is also well correlated with the geodetic observations. Significant discrepancies exist between the solutions of each centre. The source of these differences is probably related to the data processing strategy. We also consider residuals computed after removing the geophysical models or the gravimetric solutions from the geodetic mass term. We show that the residual excitation based on models is smoother than the gravimetric data, which are still noisy. Still, they are comparable for the χ2 component. It appears that χ2 residual signals using GFZ and JPL data have less variability. Finally, for assessing the impact of the geophysical fluids models choice on our results, we checked two different oceanic excitation series. We show the significant differences in the residuals correlations, especially for the χ1 more sensitive to the oceanic signals.

Predictive impact on medium-term mortality of hematological parameters in Acute Coronary Syndromes: added value on top of GRACE risk score.

Science.gov (United States)

Timóteo, Ana T; Papoila, Ana L; Lousinha, Ana; Alves, Marta; Miranda, Fernando; Ferreira, Maria L; Ferreira, Rui C

2015-04-01

Red Cell Distribution Width (RDW) prognostic value in patients with Acute Coronary Syndrome (ACS) has been well validated whereas that of Platelet Distribution Width (PDW) is less well known. Investigate the incremental prognostic value, on top of GRACE risk score, of a new variable resulting from the combination of RDW and PDW. Consecutive patients with ACS. Complete blood count, with RDW and PDW, was obtained. Primary endpoint was one-year all-cause mortality and Cox regression models were used to measure the influence of RDW and PDW on patients' survival time. A new combination categorical variable (RDW/PDW) was created with both discretized RDW and PDW and logistic regression models were used. Predictive value and discriminative ability of the model with GRACE risk score alone and of the model with inclusion of RDW/PDW was assessed. We included 787 patients. Hospital and one-year mortality rates were 5.1% and 7.8%, respectively. Both continuous RDW and PDW were independent predictors of death. The best cut-off for RDW was 13.9%, and 14.5% for PDW. Inclusion of RDW/PDW in a model with GRACE risk score improved the AUC from 0.81 (95% CI 0.75-0.86) to 0.84 (95% CI 0.79-0.90) (p=0.024) with an improvement in total NRI (56%) and IDI (0.048). Simple markers such as RDW and PDW can be useful in risk stratification of death after ACS. Combining both markers with GRACE risk score improved the predictive value for all-cause mortality and reduced the estimated risk of those who did not die. © The European Society of Cardiology 2014.

Drought Analysis of the Haihe River Basin Based on GRACE Terrestrial Water Storage

Directory of Open Access Journals (Sweden)

Jianhua Wang

2014-01-01

Full Text Available The Haihe river basin (HRB in the North China has been experiencing prolonged, severe droughts in recent years that are accompanied by precipitation deficits and vegetation wilting. This paper analyzed the water deficits related to spatiotemporal variability of three variables of the gravity recovery and climate experiment (GRACE derived terrestrial water storage (TWS data, precipitation, and EVI in the HRB from January 2003 to January 2013. The corresponding drought indices of TWS anomaly index (TWSI, precipitation anomaly index (PAI, and vegetation anomaly index (AVI were also compared for drought analysis. Our observations showed that the GRACE-TWS was more suitable for detecting prolonged and severe droughts in the HRB because it can represent loss of deep soil water and ground water. The multiyear droughts, of which the HRB has sustained for more than 5 years, began in mid-2007. Extreme drought events were detected in four periods at the end of 2007, the end of 2009, the end of 2010, and in the middle of 2012. Spatial analysis of drought risk from the end of 2011 to the beginning of 2012 showed that human activities played an important role in the extent of drought hazards in the HRB.

DIANE, a simulation code for the interaction of neutrons with living tissues. Application to low doses of fast neutrons on human tumoral cells; DIANE, un code de simulation de l'interaction des neutrons avec la matiere vivante. Applications aux faibles doses de neutrons rapides sur des cellules tumorales humaines

Energy Technology Data Exchange (ETDEWEB)

Nenot, M.L

2003-07-15

Our work deals with the irradiation of cells and living tissues by 14 MeV neutrons at very low doses (a few 10{sup -2} Gy). Such experiments require an accurate knowledge of the values of neutron dose rates and fluences at the level of cell cultures. We have performed measurements of fluence rates through an activation method applied to gold and copper foils. The fluence rate is deduced from the gamma rays emitted by the irradiated foils. Neutron doses and dose rates have been measured through varied methods: PIN diodes, ionization tissue equivalent chambers, and Geiger-Mueller counters. We have designed the DIANE code to simulate the impact of energetic neutrons on cells. This code can be used with isolated cells or macroscopic tissues, it takes into account the roles of the ionisation electrons produced by recoil nuclei entering the cell. This point is all the more important since recent works have highlighted the impact of very low energy electrons on DNA. (A.C.)

Distributed fault slip model for the 2011 Tohoku-Oki earthquake from GNSS and GRACE/GOCE satellite gravimetry

NARCIS (Netherlands)

Fuchs, Martin Johann; Hooper, Andrew; Broerse, D.B.T.; Bouman, Johannes

2016-01-01

The Gravity Recovery and Climate Experiment (GRACE) mission (launched 2002) and the Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) mission (March 2009 to November 2013) collected spaceborne gravity data for the preseismic and postseismic periods of the 2011 Tohoku-Oki

Distributed fault slip model for the 2011 Tohoku-Oki earthquake from GNSS and GRACE/GOCE satellite gravimetry

NARCIS (Netherlands)

Fuchs, Martin Johann; Hooper, Andrew; Broerse, Taco|info:eu-repo/dai/nl/411299344; Bouman, Johannes

The Gravity Recovery and Climate Experiment (GRACE) mission (launched 2002) and the Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) mission (March 2009 to November 2013) collected spaceborne gravity data for the preseismic and postseismic periods of the 2011 Tohoku-Oki earthquake.

Long term ice sheet mass change rates and inter-annual variability from GRACE gravimetry.

Science.gov (United States)

Harig, C.

2017-12-01

The GRACE time series of gravimetry now stretches 15 years since its launch in 2002. Here we use Slepian functions to estimate the long term ice mass trends of Greenland, Antarctica, and several glaciated regions. The spatial representation shows multi-year to decadal regional shifts in accelerations, in agreement with increases in radar derived ice velocity. Interannual variations in ice mass are of particular interest since they can directly link changes in ice sheets to the drivers of change in the polar ocean and atmosphere. The spatial information retained in Slepian functions provides a tool to determine how this link varies in different regions within an ice sheet. We present GRACE observations of the 2013-2014 slowdown in mass loss of the Greenland ice sheet, which was concentrated in specific parts of the ice sheet and in certain months of the year. We also discuss estimating the relative importance of climate factors that control ice mass balance, as a function of location of the glacier/ice cap as well as the spatial variation within an ice sheet by comparing gravimetry with observations of surface air temperature, ocean temperature, etc. as well as model data from climate reanalysis products.

W.R. Grace: Plant Uses Six Sigma Methodology and Traditional Heat Balance Analysis to Identify Energy Conservation Opportunities at Curtis Bay Works

Energy Technology Data Exchange (ETDEWEB)

None

2003-12-01

The plant-wide energy assessment at W. R. Grace's Curtis Bay Works helped identify four projects with combined potential savings of $840,000 per year. A separate, unique project that would partner W. R. Grace with the City of Baltimore to recover and use landfill gas (methane) to cogenerate steam and electricity was also identified during the assessment. If implemented, the project would recover gas from the landfill to replace 40% of the electricity and 65% of the fuel currently required to produce steam at Curtis Bay Works. Annual savings are estimated at $900,000 to $1.2 million.

Crustal structure of the southeastern Tibetan Plateau from gravity data: New evidence for clockwise movement of the Chuan-Dian rhombic block

Science.gov (United States)

Xuan, Songbai; Shen, Chongyang; Shen, Wenbin; Wang, Jiapei; Li, Jianguo

2018-06-01

The crustal deformation beneath the Chuan-Dian rhombic block (CDB) and surrounding regions has been studied in geological and geodetic methods, and provide important insights into the kinematics and dynamics about the clockwise movement of this tectonic block. In this work, we present images of the normalized full gradient (NFG) of the Bouguer gravity anomalies from five gravity profiles across the boundary faults of the CDB measured in recent years, and investigate the distribution characteristics of the crustal anomalous bodies along the profiles. Firstly, an anomalous body with eastward dipping exist beneath the Xianshuihe fault, suggesting that crustal mass move to east. Secondly, near the Xiaojiang fault, two anomalous bodies dip westward with depth increasing. The inferred movement direction of the north one is from west to east, and the south one is from east to west. Thirdly, anomalous bodies on the northeast and southwest sides of the Red River fault suggest the directions of crustal movement is from northeast to southwest. These results are also consistent with GPS solutions, and provide gravity evidence for crustal deformation of the CDB with clockwise rotation.

The Impact of Atmospheric Modeling Errors on GRACE Estimates of Mass Loss in Greenland and Antarctica

Science.gov (United States)

Hardy, Ryan A.; Nerem, R. Steven; Wiese, David N.

2017-12-01

Systematic errors in Gravity Recovery and Climate Experiment (GRACE) monthly mass estimates over the Greenland and Antarctic ice sheets can originate from low-frequency biases in the European Centre for Medium-Range Weather Forecasts (ECMWF) Operational Analysis model, the atmospheric component of the Atmospheric and Ocean Dealising Level-1B (AOD1B) product used to forward model atmospheric and ocean gravity signals in GRACE processing. These biases are revealed in differences in surface pressure between the ECMWF Operational Analysis model, state-of-the-art reanalyses, and in situ surface pressure measurements. While some of these errors are attributable to well-understood discrete model changes and have published corrections, we examine errors these corrections do not address. We compare multiple models and in situ data in Antarctica and Greenland to determine which models have the most skill relative to monthly averages of the dealiasing model. We also evaluate linear combinations of these models and synthetic pressure fields generated from direct interpolation of pressure observations. These models consistently reveal drifts in the dealiasing model that cause the acceleration of Antarctica's mass loss between April 2002 and August 2016 to be underestimated by approximately 4 Gt yr-2. We find similar results after attempting to solve the inverse problem, recovering pressure biases directly from the GRACE Jet Propulsion Laboratory RL05.1 M mascon solutions. Over Greenland, we find a 2 Gt yr-1 bias in mass trend. While our analysis focuses on errors in Release 05 of AOD1B, we also evaluate the new AOD1B RL06 product. We find that this new product mitigates some of the aforementioned biases.

Application of GRACE to the Evaluation of an Ice Flow Model of the Greenland Ice Sheet

Science.gov (United States)

Schlegel, N.; Wiese, D. N.; Watkins, M. M.; Larour, E. Y.; Box, J. E.; Fettweis, X.; van den Broeke, M. R.; Morlighem, M.; Boening, C.; Seroussi, H. L.

2014-12-01

Quantifying Greenland's future contribution to sea level rise is a challenging task and requires accurate estimates of ice flow sensitivity to climate change. Transient ice flow models are promising tools for estimating future ice sheet behavior. However, confidence in these types of future projections is low, especially because evaluation of model historical runs is so challenging due to the scarcity of continental-wide data for validation. For more than a decade, NASA's GRACE has continuously acquired time-variable measurements of the Earth's gravity field and has provided unprecedented surveillance of mass balance of the ice sheets, offering an opportunity for ice sheet model evaluation. Here, we take advantage of a new high-resolution (~300 km) monthly mascon solution for the purpose of mass balance comparison with an independent, historical ice flow model simulation using the Ice Sheet System Model (ISSM). The comparison highlights which regions of the ice sheet differ most from GRACE. Investigation of regional differences in trends and seasonal amplitudes between simulations forced with three different Regional Climate Model (RCM)-based estimates of surface mass balance (SMB) allows us to make conclusions about the relative contributions of various error sources in the model hindcast. This study constitutes the first regional comparison of GRACE data and an ice sheet model. Conclusions will aid in the improvement of RCM SMB estimates as well as ice sheet simulation estimates of present and future rates of sea level rise. This work was performed at the California Institute of Technology's Jet Propulsion Laboratory under a contract with the National Aeronautics and Space Administration's Cryosphere Program and President's and Director's Fund Program.

The effect of signal leakage and glacial isostatic rebound on GRACE-derived ice mass changes in Iceland

DEFF Research Database (Denmark)

Sørensen, Louise Sandberg; Jarosch, Alexander H.; Adalgeirsdottir, Gudfinna

2017-01-01

Monthly gravity field models from the GRACE satellite mission are widely used to determine ice mass changes of large ice sheets as well as smaller glaciers and ice caps. Here, we investigate in detail the ice mass changes of the Icelandic ice caps as derived from GRACE data. The small size...... of the Icelandic ice caps, their location close to other rapidly changing ice covered areas and the low viscosity of the mantle below Iceland make this especially challenging. The mass balance of the ice caps is well constrained by field mass balance measurements, making this area ideal for such investigations. We...... the Little Ice Age (∼ 1890 AD). To minimize the signal that leaks towards Iceland from Greenland, we employ an independent mass change estimate of the Greenland Ice Sheet derived from satellite laser altimetry. We also estimate the effect of post Little Ice Age glacial isostatic adjustment, from knowledge...

Influence of the Three Gorges Project on the Water Resource Components of Poyang Lake Watershed: Observations from TRMM and GRACE

Directory of Open Access Journals (Sweden)

Xiaobin Cai

2015-01-01

Full Text Available The Three Gorges Project (TGP has received many criticisms about its potential effects on the changes in the downstream ecosystems. Poyang Lake is the largest body of water downstream of the TGP, and it is not immune to these changes. TRMM and GRACE data were introduced in this study to estimate river-lake water exchange, from which the hydrological responses of Poyang Lake could be identified. A significant decreasing trend of the runoff coefficient has been observed since 2003, resulting in 6.02 km3 more water discharge from the lake into the Yangtze River than under normal conditions. No significant interannual changes occurred in the water level or local precipitation, and GRACE observations revealed that groundwater discharge appeared to be the most likely compensation for the water loss. A novel approach, namely, the groundwater abnormality index (GAI, was developed to depict the water exchange using GRACE and surface water observations. Lower than normal GAIs were found between 2003 and 2005, reaching a minimum of −29.26 in October 2003, corresponding to ten times of the mean GAI during 2006–2012, clearly indicating a significant water exchange in Poyang Lake Basin from groundwater to surface water after the TGP impoundment.

On the estimation of physical height changes using GRACE satellite mission data – A case study of Central Europe

Directory of Open Access Journals (Sweden)

Godah Walyeldeen

2017-12-01

Full Text Available The dedicated gravity satellite missions, in particular the GRACE (Gravity Recovery and Climate Experiment mission launched in 2002, provide unique data for studying temporal variations of mass distribution in the Earth’s system, and thereby, the geometry and the gravity fi eld changes of the Earth. The main objective of this contribution is to estimate physical height (e.g. the orthometric/normal height changes over Central Europe using GRACE satellite mission data as well as to analyse them and model over the selected study area. Physical height changes were estimated from temporal variations of height anomalies and vertical displacements of the Earth surface being determined over the investigated area. The release 5 (RL05 GRACE-based global geopotential models as well as load Love numbers from the Preliminary Reference Earth Model (PREM were used as input data. Analysis of the estimated physical height changes and their modelling were performed using two methods: the seasonal decomposition method and the PCA/ EOF (Principal Component Analysis/Empirical Orthogonal Function method and the differences obtained were discussed. The main fi ndings reveal that physical height changes over the selected study area reach up to 22.8 mm. The obtained physical height changes can be modelled with an accuracy of 1.4 mm using the seasonal decomposition method.

DIANE, a simulation code for the interaction of neutrons with living tissues. Application to low doses of fast neutrons on human tumoral cells

International Nuclear Information System (INIS)

Nenot, M.L.

2003-07-01

Our work deals with the irradiation of cells and living tissues by 14 MeV neutrons at very low doses (a few 10 -2 Gy). Such experiments require an accurate knowledge of the values of neutron dose rates and fluences at the level of cell cultures. We have performed measurements of fluence rates through an activation method applied to gold and copper foils. The fluence rate is deduced from the gamma rays emitted by the irradiated foils. Neutron doses and dose rates have been measured through varied methods: PIN diodes, ionization tissue equivalent chambers, and Geiger-Mueller counters. We have designed the DIANE code to simulate the impact of energetic neutrons on cells. This code can be used with isolated cells or macroscopic tissues, it takes into account the roles of the ionisation electrons produced by recoil nuclei entering the cell. This point is all the more important since recent works have highlighted the impact of very low energy electrons on DNA. (A.C.)

Seasonal changes in the European gravity field from GRACE: A comparison with superconducting gravimeters and hydrology model predictions

DEFF Research Database (Denmark)

Hinderer, J.; Andersen, Ole Baltazar; Lemoine, F.

2006-01-01

This paper is devoted to the investigation of seasonal changes of the Earth's gravity field from GRACE satellites and the comparison with surface gravity measurements in Europe from the Global Geodynamics Project (GGP) sub-network, as well as with recent hydrology models for continental soil...... moisture and snow. We used gravity maps in Europe retrieved from the initial GRACE monthly solutions spanning a 21 -month duration from April 2002 to December 2003 for various truncation levels of the initial spherical harmonic decomposition of the field. The transfer function between satellite......-derived and ground gravity changes due to continental hydrology is studied and we also compute the theoretical ratio of gravity versus radial displacement (in mu Gal/mm) involved in the hydrological loading process. The 'mean' value (averaged in time and in space over Europe) from hydrologic forward modeling...

GRACE Detected Rise of Groundwater in the Sahelian Niger River Basin

Science.gov (United States)

Werth, S.; White, D.; Bliss, D. W.

2017-12-01

West African regions along the Niger River experience climate and land cover changes that affect hydrological processes and therewith the distribution of fresh water resources (WR). This study provides an investigation of long-term changes in terrestrial water storages (TWS) of the Niger River basin and its subregions by analyzing a decade of satellite gravity data from the Gravity Recovery and Climate Experiment (GRACE) mission. The location of large trends in TWS maps of differently processed GRACE solutions points to rising groundwater stocks. Soil moisture data from a global land surface model allow separating the effect of significantly increasing amount of WR from that of TWS variations. Surface water variations from a global water storage model validated with observations from altimetry data were applied to estimate the groundwater component in WR. For the whole Niger, a rise in groundwater stocks is estimated to be 93 ± 61 km3 between January 2003 and December 2013. A careful analysis of uncertainties in all data sets supports the significance of the groundwater rise. Our results confirm previous observations of rising water tables, indicating that effects of land cover changes on groundwater storage are relevant on basin scales. Areas with rising water storage are stocking a comfortable backup to mitigate possible future droughts and to deliver water to remote areas. This has implications for Niger water management strategies. Increasing groundwater recharges may be accompanied by reduction in water quality. This study helps to inform authority's decision to mitigate its negative impacts on local communities.

GRACE-based estimates of water discharge over the Yellow River basin

Directory of Open Access Journals (Sweden)

Qiong Li

2016-05-01

Full Text Available As critical component of hydrologic cycle, basin discharge is a key issue for understanding the hydrological and climatologic related to water and energy cycles. Combining GRACE gravity field models with ET from GLDAS models and precipitation from GPCP, discharge of the Yellow River basin are estimated from the water balance equation. While comparing the results with discharge from GLDAS model and in situ measurements, the results reveal that discharge from Mosaic and CLM GLDAS model can partially represent the river discharge and the discharge estimation from water balance equation could reflect the discharge from precipitation over the Yellow River basin.

Arctic Ocean gravity, geoid and sea-ice freeboard heights from ICESat and GRACE

DEFF Research Database (Denmark)

Forsberg, René; Skourup, Henriette

2005-01-01

Gravity Project in combination with GRACE gravity field models to derive an improved Arctic geoid model. This model is then used to convert ICESat measurements to sea-ice freeboard heights with a coarse lowest-level surface method. The derived freeboard heights show a good qualitative agreement...... all major tectonic features of the Arctic Ocean, and has an accuracy of 6 mGal compared to recent airborne gravity data, illustrating the usefulness of ICESat data for gravity field determination....

W. R. Grace: Plant Uses Six Sigma Methodology and Traditional Heat Balance Analysis to Identify Energy Conservation Opportunities at Curtis Bay Works (Revised)

Energy Technology Data Exchange (ETDEWEB)

2003-12-01

The plant-wide energy assessment at W. R. Grace's Curtis Bay Works helped identify four projects with combined potential savings of $840,000 per year. A separate, unique project that would partner W. R. Grace with the City of Baltimore to recover and use landfill gas (methane) to cogenerate steam and electricity was also identified during the assessment. If implemented, the project would recover gas from the landfill to replace 40% of the electricity and 65% of the fuel currently required to produce steam at Curtis Bay Works. Annual savings are estimated at $900,000 to $1.2 million.

Modelling the Earth's static and time-varying gravity field using a combination of GRACE and GOCE data

NARCIS (Netherlands)

Farahani, H.H.

2013-01-01

The main focus of the thesis is modelling the static and time-varying parts of the Earth's gravity field at the global scale based on data acquired by the Gravity Recovery And Climate Experiment (GRACE) and Gravity field and steady-state Ocean Circulation Explorer (GOCE). In addition, a new

A New Model of the Mean Albedo of the Earth: Estimation and Validation from the GRACE Mission and SLR Satellites.

Science.gov (United States)

Deleflie, F.; Sammuneh, M. A.; Coulot, D.; Pollet, A.; Biancale, R.; Marty, J. C.

2017-12-01

This talk provides new results of a study that we began last year, and that was the subject of a poster by the same authors presented during AGU FM 2016, entitled « Mean Effect of the Albedo of the Earth on Artificial Satellite Trajectories: an Update Over 2000-2015. »The emissivity of the Earth, split into a part in the visible domain (albedo) and the infrared domain (thermic emissivity), is at the origin of non gravitational perturbations on artificial satellite trajectories. The amplitudes and periods of these perturbations can be investigated if precise orbits can be carried out, and reveal some characteristics of the space environment where the satellite is orbiting. Analyzing the perturbations is, hence, a way to characterize how the energy from the Sun is re-emitted by the Earth. When led over a long period of time, such an approach enables to quantify the variations of the global radiation budget of the Earth.Additionally to the preliminary results presented last year, we draw an assessment of the validity of the mean model based on the orbits of the GRACE missions, and, to a certain extent, of some of the SLR satellite orbits. The accelerometric data of the GRACE satellites are used to evaluate the accuracy of the models accounting for non gravitational forces, and the ones induced by the albedo and the thermic emissivity in particular. Three data sets are used to investigate the mean effects on the orbit perturbations: Stephens tables (Stephens, 1980), ECMWF (European Centre for Medium-Range Weather Forecasts) data sets and CERES (Clouds and the Earth's Radiant Energy System) data sets (publickly available). From the trajectography point of view, based on post-fit residual analysis, we analyze what is the data set leading to the lowest residual level, to define which data set appears to be the most suitable one to derive a new « mean albedo model » from accelerometric data sets of the GRACE mission. The period of investigation covers the full GRACE

Improved GRACE regional mass balance estimates of the Greenland ice sheet cross-validated with the input-output method

NARCIS (Netherlands)

Xu, Zheng; Schrama, Ernst J. O.; van der Wal, Wouter; van den Broeke, Michiel; Enderlin, Ellyn M.

2016-01-01

In this study, we use satellite gravimetry data from the Gravity Recovery and Climate Experiment (GRACE) to estimate regional mass change of the Greenland ice sheet (GrIS) and neighboring glaciated regions using a least squares inversion approach. We also consider results from the input–output

Improved GRACE regional mass balance estimates of the Greenland ice sheet cross-validated with the input–output method

NARCIS (Netherlands)

Xu, Z.; Schrama, E.J.O.; van der Wal, W.; van den Broeke, MR; Enderlin, EM

2016-01-01

In this study, we use satellite gravimetry data from the Gravity Recovery and Climate Experiment (GRACE) to estimate regional mass change of the Greenland ice sheet (GrIS) and neighboring glaciated regions using a least squares inversion approach. We also consider results from the input–output

Using GRACE Amplitude Data in Conjunction with the Spatial Distribution of Groundwater Recharge to Estimate the Components of the Terrestrial Water Storage Anomaly across the Contiguous United States

Science.gov (United States)

Sanford, W. E.; Reitz, M.; Zell, W.

2017-12-01

The GRACE satellite project by NASA has been mapping the terrestrial water storage anomaly (TWSA) across the globe since 2002. To date most of the studies using this data have focused on estimating long-term storage declines in groundwater aquifers or the cryosphere. In this study we are focusing on using the amplitude of the seasonal storage signal to estimate the sources and values of the different water components that are contributing to the TWSA signal across the contiguous United States (CONUS). Across the CONUS the TWSA seasonal amplitude observed by GRACE varies by a factor of ten or more (from 1 to 10+ cm of liquid water equivalent). For a seasonal sinusoidal recharge rate, the change in storage in either the soil (unsaturated zone beneath the root zone) or groundwater (by water-table fluctuation) is limited to the amplitude of the recharge rate divided by π or 2π, respectively. We compiled the GRACE signal for the 18 major HUC watersheds across the CONUS and compared them to estimates of seasonal recharge-rate amplitudes based on a recent map of recharge rates generated by the USGS. The ratios of the recharge to GRACE amplitudes suggest that all but two of the HUCs must have other substantial sources of storage change in addition to soil or groundwater. The most likely additional sources are (1) winter snowpack, (2) seasonal irrigation withdrawals, and/or (3) surface water (rivers or reservoirs). Estimates of the seasonal amplitudes of these three signals across the CONUS suggest they can explain the remaining GRACE seasonal signal that cannot be explained by soil or groundwater fluctuations. Each of these signals has its own unique spatial distribution, with snowpack limited to the northern states, surface water limited to large rivers or reservoirs, and irrigation as a dominant signal limited to arid to semi-arid agricultural regions. Use of the GRACE seasonal signal shows promise in constraining the hydraulic diffusivities of surficial aquifer

Time-variations of equivalent water heights'from Grace Mission and in-situ river stages in the Amazon basin Variações temporais do equivalente à altura d'água obtidas da Missão Grace e da altura d'água in-situ nos rios da bacia Amazônica

Directory of Open Access Journals (Sweden)

Flavio Guilherme Vaz de Almeida

2012-03-01

Full Text Available Gravity Recovery and Climate Experiment (GRACE mission is dedicated to measuring temporal variations of the Earth's gravity field. In this study, the Stokes coefficients made available by Groupe de Recherche en Géodésie Spatiale (GRGS at a 10-day interval were converted into equivalent water height (EWH for a ~4-year period in the Amazon basin (from July-2002 to May-2006. The seasonal amplitudes of EWH signal are the largest on the surface of Earth and reach ~ 1250mm at that basin's center. Error budget represents ~130 mm of EWH, including formal errors on Stokes coefficient, leakage errors (12 ~ 21 mm and spectrum truncation (10 ~ 15 mm. Comparison between in situ river level time series measured at 233 ground-based hydrometric stations (HS in the Amazon basin and vertically-integrated EWH derived from GRACE is carried out in this paper. Although EWH and HS measure different water bodies, in most of the cases a high correlation (up to ~80% is detected between the HS series and EWH series at the same site. This correlation allows adjusting linear relationships between in situ and GRACE-based series for the major tributaries of the Amazon river. The regression coefficients decrease from up to down stream along the rivers reaching the theoretical value 1 at the Amazon's mouth in the Atlantic Ocean. The variation of the regression coefficients versus the distance from estuary is analysed for the largest rivers in the basin. In a second step, a classification of the proportionality between in situ and GRACE time-series is proposed.A missão espacial Gravity Recovery and Climate Experiment (GRACE é dedicada às medidas das variações temporais no campo gravitacional da Terra. Neste estudo, os coeficientes de Stokes disponibilizados pelo Groupe de Recherche en Géodésie Spatiale (GRGS com intervalos de 10 dias foram convertidos no equivalente à altura d'água (EWH para um período de 4 anos na bacia Amazônica (de julho de 2002 a maio de 2006

Status and Assessments of CSR GRACE Level-2 Data Products

Science.gov (United States)

Bettadpur, Srinivas; Kang, Zhigui; Nagel, Peter; Pastor, Rick; Poole, Steve; Ries, John; Save, Himanshu

2015-04-01

The joint NASA/DLR GRACE mission has successfully operated for more than 13 years, and has provided a remarkable record of global mass flux due to a large variety of geophysical and climate processes at various spatio-temporal scales. The University of Texas Center for Space Research (CSR) hosts the mission PI, and is responsible for delivery of operational (presently denoted as Release-05 or RL05) gravity field data products. In addition, CSR generates and distributes a variety of other gravity field data products, including products generated from the use of satellite laser ranging data. This poster will provide an overview of all these data products, their relative quality, potential applications, and future plans for their development and delivery.

Improved estimation of geocenter motion and changes in the Earth's dynamic oblateness from GRACE data and an ocean bottom pressure model

Science.gov (United States)

Sun, Y.; Ditmar, P.; Riva, R.

2015-12-01

The Gravity Recovery and Climate Experiment (GRACE) satellite mission, since the launch in 2002, has enabled the monitoring of mass transport in the Earth's system on a monthly basis. In spite of continuous improvements in data processing techniques, an estimation of very low-degree spherical harmonic coefficients remains problematic. GRACE is insensitive to variations in the degree-1 coefficients (ΔC11, ΔS11 and ΔC10), which reflect the motion of the geocenter. The variations of C20 coefficients, which characterize changes in the Earth's dynamic oblateness (Δ J2) are corrupted by ocean tide aliases and usually replaced with estimates from other techniques.In this study, the methodology proposed by Swenson et al. (2008) to estimate geocenter motion is updated and extended to co-estimate changes in the Earth's dynamic oblateness. The algorithm uses monthly GRACE gravity solutions (in the form of spherical harmonic coefficients), an ocean bottom pressure model (over the oceans), and a glacial isostatic adjustment (GIA) model (globally). GRACE solutions over coastal areas may suffer from signal leakage due to their limited spectral content and to filtering. We effectively avoid the influence of this effect by introducing a carefully chosen buffer zone. We also take into account self-attraction and loading effects when dealing with water redistribution in the oceans. The estimated annual amplitude of ΔC10 , i.e. the Z component of the geocenter motion, is significantly amplified compared to the original estimations of Swenson et al. (2008) and it is in line with estimates from other techniques, such as the global GPS inversion. The resulting ΔC20 time-series agree remarkably well with a solution based on satellite laser ranging data, which is currently believed to be one of the most accurate sources of information on changes in the Earth's dynamic oblateness. Trends in both geocenter position and the Earth's oblateness are estimated as well. The results show a

Recovery of the Three-Gorges Reservoir Impoundment Signal from ICESat altimetry and GRACE

Science.gov (United States)

Carabajal, C. C.; Boy, J.; Luthcke, S. B.; Harding, D. J.; Rowlands, D. D.; Lemoine, F. G.

2006-12-01

The Three Gorges Dam along the Yangtze River in China is one of the largest dams in the world. The water impoundment of the Three-Gorges Reservoir started in June 2003, and the volume of water will continuously increase up to about 40 km3 in 2009, over a length of about 600 km. Although water-level changes along the Yangtze River and the Three Gorges Reservoir are measured by in situ water gauges, access to these data can be quite difficult. Estimates of inland water height and extent can also be recovered from altimetry measurements performed from satellite platforms, such as those acquired by the Geoscience laser Altimetry System (GLAS) on board the Ice, Cloud and Land Elevation Satellite (ICESat). ICESat has produced a comprehensive, highly precise, set of along-track elevation measurements, every three months since its launch in 2003, which intersect the Yangtze River along its East-West extent. In addition, the water impoundment of major artificial reservoirs induces variations of global geodetic quantities, such as the gravity field and Earth rotation (Chao, 1995, Boy & Chao, 2002). Water level changes within the reservoir are compared to GRACE (Gravity Recovery And Climate Experiment) recovered water mass changes. In addition, we compare the GRACE observations of mass change in the Yangtze region to hydrological changes computed from different global soil-moisture and snow models, such as GLDAS (Global Land Data Assimilation System).

Assessing groundwater depletion and dynamics using GRACE and InSAR: Potential and limitations

Science.gov (United States)

Castellazzi, Pascal; Martel, Richard; Galloway, Devin L.; Longuevergne, Laurent; Rivera, Alfonso

2016-01-01

In the last decade, remote sensing of the temporal variation of ground level and gravity has improved our understanding of groundwater dynamics and storage. Mass changes are measured by GRACE (Gravity Recovery and Climate Experiment) satellites, whereas ground deformation is measured by processing synthetic aperture radar satellites data using the InSAR (Interferometry of Synthetic Aperture Radar) techniques. Both methods are complementary and offer different sensitivities to aquifer system processes. GRACE is sensitive to mass changes over large spatial scales (more than 100,000 km2). As such, it fails in providing groundwater storage change estimates at local or regional scales relevant to most aquifer systems, and at which most groundwater management schemes are applied. However, InSAR measures ground displacement due to aquifer response to fluid-pressure changes. InSAR applications to groundwater depletion assessments are limited to aquifer systems susceptible to measurable deformation. Furthermore, the inversion of InSAR-derived displacement maps into volume of depleted groundwater storage (both reversible and largely irreversible) is confounded by vertical and horizontal variability of sediment compressibility. During the last decade, both techniques have shown increasing interest in the scientific community to complement available in situ observations where they are insufficient. In this review, we present the theoretical and conceptual bases of each method, and present idealized scenarios to highlight the potential benefits and challenges of combining these techniques to remotely assess groundwater storage changes and other aspects of the dynamics of aquifer systems.

Combination of GRACE monthly gravity field solutions from different processing strategies

Science.gov (United States)

Jean, Yoomin; Meyer, Ulrich; Jäggi, Adrian

2018-02-01

We combine the publicly available GRACE monthly gravity field time series to produce gravity fields with reduced systematic errors. We first compare the monthly gravity fields in the spatial domain in terms of signal and noise. Then, we combine the individual gravity fields with comparable signal content, but diverse noise characteristics. We test five different weighting schemes: equal weights, non-iterative coefficient-wise, order-wise, or field-wise weights, and iterative field-wise weights applying variance component estimation (VCE). The combined solutions are evaluated in terms of signal and noise in the spectral and spatial domains. Compared to the individual contributions, they in general show lower noise. In case the noise characteristics of the individual solutions differ significantly, the weighted means are less noisy, compared to the arithmetic mean: The non-seasonal variability over the oceans is reduced by up to 7.7% and the root mean square (RMS) of the residuals of mass change estimates within Antarctic drainage basins is reduced by 18.1% on average. The field-wise weighting schemes in general show better performance, compared to the order- or coefficient-wise weighting schemes. The combination of the full set of considered time series results in lower noise levels, compared to the combination of a subset consisting of the official GRACE Science Data System gravity fields only: The RMS of coefficient-wise anomalies is smaller by up to 22.4% and the non-seasonal variability over the oceans by 25.4%. This study was performed in the frame of the European Gravity Service for Improved Emergency Management (EGSIEM; http://www.egsiem.eu) project. The gravity fields provided by the EGSIEM scientific combination service (ftp://ftp.aiub.unibe.ch/EGSIEM/) are combined, based on the weights derived by VCE as described in this article.

Estimating a Global Hydrological Carrying Capacity Using GRACE Observed Water Stress

Science.gov (United States)

An, K.; Reager, J. T.; Famiglietti, J. S.

2013-12-01

Global population is expected to reach 9 billion people by the year 2050, causing increased demands for water and potential threats to human security. This study attempts to frame the overpopulation problem through a hydrological resources lens by hypothesizing that observed groundwater trends should be directly attributed to human water consumption. This study analyzes the relationships between available blue water, population, and cropland area on a global scale. Using satellite data from NASA's Gravity Recovery and Climate Experiment (GRACE) along with land surface model data from the Global Land Data Assimilation System (GLDAS), a global groundwater depletion trend is isolated, the validity of which has been verified in many regional studies. By using the inherent distributions of these relationships, we estimate the regional populations that have exceeded their local hydrological carrying capacity. Globally, these populations sum to ~3.5 billion people that are living in presently water-stressed or potentially water-scarce regions, and we estimate total cropland is exceeding a sustainable threshold by about 80 million km^2. Key study areas such as the North China Plain, northwest India, and Mexico City were qualitatively chosen for further analysis of regional water resources and policies, based on our distributions of water stress. These case studies are used to verify the groundwater level changes seen in the GRACE trend . Tfor the many populous, arid regions of the world that have already begun to experience the strains of high water demand.he many populous, arid regions of the world have already begun to experience the strains of high water demand. It will take a global cooperative effort of improving domestic and agricultural use efficiency, and summoning a political will to prioritize environmental issues to adapt to a thirstier planet. Global Groundwater Depletion Trend (Mar 2003-Dec 2011)

Faith and grace in the thought of Tanabe Hajime and of Søren Kierkegaard

OpenAIRE

Henneberg, Peter

2010-01-01

The subject matter of this essay is to compare the conceptions which Søren Kierkegaard and Tanabe Hajime have of the notions of religious faith and of divine grace. The investigation was triggered by the observation that Tanabe’s philosophy owes much to the thought of Kierkegaard, and by the fact that Kierkegaard has been trained as a Danish Protestant theologian while Tanabe adopted for himself positions of Japanese Pure Land Buddhism. After a rigorous analysis of the notions of faith and...

Gravity Variation in Siberia: GRACE Observation and Possible Causes

Directory of Open Access Journals (Sweden)

Benjamin Fong Chao

2011-01-01

Full Text Available We report the finding, from the GRACE observation, of an increasing trend in the gravity anomaly in Siberia at the rate of up to 0.5 ugal yr-1 during 2003/1 - 2009/12, in the backdrop of a negative anomaly of magnitude on the order of ~-10 mgal. In consideration of the non-uniqueness of the gravitational inverse problem, we examine in some detail the various possible geophysical causes to explain the increasing gravity signal. We find two geophysical mechanisms being the most plausible, namely the melting of permafrost and the GIA post-glacial rebound. We conclude that these two mechanisms cannot be ruled out as causes for the regional gravity increase in Siberia, based on gravity data and in want of ancillary geophysical data in the region. More definitive identification of the contributions of the various causes awaits further studies.

Dissatisfaction of Compact Picard Condition (CPC) with GRACE satellite data and its treatment by Generalized Tikhonov in Sobolev subspace

Science.gov (United States)

AllahTavakoli, Y.; Bagheri, H.; Safari, A.; Sharifi, M.

2012-04-01

This paper is mainly aiming to prove that the stripy noises in the map of earth's surface mass-density changes derived from GRACE Satellites gravimetry, is due to a dissatisfaction of Compact Picard Condition (CPC) with the GRACE data in the inversion of the Newton Integral Equation over the thin layer of earth; and hence the paper proposes the regularization strategies as efficient tools to treat the Ill-posedness and consequently to de-strip the data. First of all, we preferred to slightly modify the mathematical model of earth's surface mass-density changes developed creatively first by J. Wahr and et.al (1998), according to the all their previous assumptions plus taking into consideration the effect of the earth topography. By the modification we expect that some uncertainties in the prior model have been reduced to some extent. Then we analyzed the CPC on the model and we demonstrated how to perform Generalized Tikhonov regularization in Sobolev subspace for overcoming the instability of the problem. Then we applied the strategy in some simulations and case studies to validate our ideas. The simulations confirm that the stripy noises in the GRACE-derived map of the mass-density changes are due to the CPC dissatisfaction and furthermore the case studies show that Generalized Tikhonov regularization in Sobolev subspace is an influential filtering tool to de-strip the noisy data. Also, the case studies interestingly show that the effect of the topography is comparable to the effect of the load Love numbers on the Wahr's model; hence it may be taken into consideration when the load Love numbers have been taken into account.

Use of GRACE determined secular gravity rates for glacial isostatic adjustment studies in North-America

Science.gov (United States)

van der Wal, Wouter; Wu, Patrick; Sideris, Michael G.; Shum, C. K.

2008-10-01

Monthly geopotential spherical harmonic coefficients from the GRACE satellite mission are used to determine their usefulness and limitations for studying glacial isostatic adjustment (GIA) in North-America. Secular gravity rates are estimated by unweighted least-squares estimation using release 4 coefficients from August 2002 to August 2007 provided by the Center for Space Research (CSR), University of Texas. Smoothing is required to suppress short wavelength noise, in addition to filtering to diminish geographically correlated errors, as shown in previous studies. Optimal cut-off degrees and orders are determined for the destriping filter to maximize the signal to noise ratio. The halfwidth of the Gaussian filter is shown to significantly affect the sensitivity of the GRACE data (with respect to upper mantle viscosity and ice loading history). Therefore, the halfwidth should be selected based on the desired sensitivity. It is shown that increase in water storage in an area south west of Hudson Bay, from the summer of 2003 to the summer of 2006, contributes up to half of the maximum estimated gravity rate. Hydrology models differ in the predictions of the secular change in water storage, therefore even 4-year trend estimates are influenced by the uncertainty in water storage changes. Land ice melting in Greenland and Alaska has a non-negligible contribution, up to one-fourth of the maximum gravity rate. The estimated secular gravity rate shows two distinct peaks that can possibly be due to two domes in the former Pleistocene ice cover: west and south east of Hudson Bay. With a limited number of models, a better fit is obtained with models that use the ICE-3G model compared to the ICE-5G model. However, the uncertainty in interannual variations in hydrology models is too large to constrain the ice loading history with the current data span. For future work in which GRACE will be used to constrain ice loading history and the Earth's radial viscosity profile, it is

La dialectique du nouveau et du même dans God's Grace de Bernard Malamud

OpenAIRE

Chard-Hutchinson, Martine

2017-01-01

What's the use avoiding rats and horror, hiding from Cops and dentists' drills ? Somebody will invent Buchenwald next door. Alan Ginzberg "If it's all right with you," he addressed the gorilla in gratitude, "I'd like to call you George after my late wife's father, who was an accomplished dentist, a wonderful man. He often fixed people's teeth for nothing." Bernard Malamud God's Grace, le dernier roman achevé de Bernard Malamud, est une histoire "pleine de fureur et de bruit" qui se présente ...

Design and baseline data from the Gratitude Research in Acute Coronary Events (GRACE) study.

Science.gov (United States)

Huffman, Jeff C; Beale, Eleanor E; Beach, Scott R; Celano, Christopher M; Belcher, Arianna M; Moore, Shannon V; Suarez, Laura; Gandhi, Parul U; Motiwala, Shweta R; Gaggin, Hanna; Januzzi, James L

2015-09-01

Positive psychological constructs, especially optimism, have been linked with superior cardiovascular health. However, there has been minimal study of positive constructs in patients with acute coronary syndrome (ACS), despite the prevalence and importance of this condition. Furthermore, few studies have examined multiple positive psychological constructs and multiple cardiac-related outcomes within the same cohort to determine specifically which positive construct may affect a particular cardiac outcome. The Gratitude Research in Acute Coronary Events (GRACE) study examines the association between optimism/gratitude 2weeks post-ACS and subsequent clinical outcomes. The primary outcome measure is physical activity at 6months, measured via accelerometer, and key secondary outcome measures include levels of prognostic biomarkers and rates of nonelective cardiac rehospitalization at 6months. These relationships will be analyzed using multivariable linear regression, controlling for sociodemographic, medical, and negative psychological factors; associations between baseline positive constructs and subsequent rehospitalizations will be assessed via Cox regression. Overall, 164 participants enrolled and completed the baseline 2-week assessment; the cohort had a mean age of 61.5+/?10.5years and was 84% men; this was the first ACS for 58% of participants. The GRACE study will determine whether optimism and gratitude are prospectively and independently associated with physical activity and other critical outcomes in the 6months following an ACS. If these constructs are associated with superior outcomes, this may highlight the importance of these constructs as independent prognostic factors post-ACS. Copyright © 2015 Elsevier Inc. All rights reserved.

Developing sustainable management scenarios for Saharan and Arabian aquifer systems using GRACE data

Science.gov (United States)

Ahmed, M.; Sultan, M.; Save, H.

2016-12-01

Three sources (CSR and JPL Mascons solutions; CSR spherical harmonic fields) of monthly (04/2002 to 03/2016) GRACE-derived TWS estimates were used to develop sustainable utilization scenarios for Saharan and Arabian aquifer systems. These aquifer systems include the Saq Aquifer System in Saudi Arabia (SAS; area: 0.46×106 km2), Nubian Aquifer System in Egypt (NAS; area: 0.66×106 km2), and the Northwestern Saharan Aquifer System in Algeria, Tunisia, and Libya (NWSAS; area: 1.2×106 km2). Piecewise trend analysis of GRACE-derived TWS time series over SAS showed steady-state TWS conditions (0.47 mm/yr; 0.22 km3/yr) during 2002-2006 (Stage I), significant TWS depletion (-13.36 mm/yr; -6.15 km3/yr) during 2006-2012 (Stage II), and signs of replenishment (-3.00 mm/yr; -1.60 km3/yr) during 2012-2016 (Stage III). The pronounced depletion in Stage II is largely related to excessive groundwater extraction mainly for irrigation purposes (2006: irrigated areas/extraction: 502,338 hectare/8.4 km3/yr) compared to those reported in Stage III (2015: irrigated areas/extraction: 326,719 hectare/7.9 km3/yr). Sustainable utilization of SAS waters can be achieved if extraction is reduced to 7.7 km3/yr. The NWSAS showed steady-state conditions (0.02 mm/yr; 0.02 km3/yr) during the 2002-2006 period followed by significant TWS depletions (-4.90 mm/yr; -5.85 km3/yr) due to progressive increase in groundwater extraction (1970: 0.6 km3/yr; 2000: 2.5 km3/yr; 2010: 3 km3/yr). Sustainable utilization of the NWSAS can be achieved if extraction is reduced to 2.5 km3/yr. Trend analysis of GRACE-derived TWS time series over NAS reveals a good correspondence with fluctuations in Lake Nasser Levels (LNL) (2002-2007: LNL/TWS: 177 m/-2.72 mm/yr; 2008-2012: LNL/TWS: 175 m/-7.35 mm/yr; 2013-2016: LNL/TWS: 179 m/11.35 mm/yr) suggesting a causal effect. Given that the average annual (04/2002 to 03/2016) depletion in TWS is -3.24 mm/yr (-2.13 km3/yr), and the average annual extraction is 2.50 km3/yr, we

Improved GRACE regional mass balance estimates of the Greenland Ice Sheet cross-validated with the input-output method (discussion paper)

NARCIS (Netherlands)

Xu, Z.; Schrama, E.J.O.; Van der Wal, W.; Van den Broeke, M.; Enderlin, E.M.

2015-01-01

In this study, we use satellite gravimetry data from the Gravity Recovery and Climate Experiment (GRACE) to estimate regional mass changes of the Greenland ice sheet (GrIS) and neighbouring glaciated regions using a least-squares inversion approach. We also consider results from the input-output

Inflation with a graceful exit in a random landscape

International Nuclear Information System (INIS)

Pedro, F.G.; Westphal, A.

2016-11-01

We develop a stochastic description of small-field inflationary histories with a graceful exit in a random potential whose Hessian is a Gaussian random matrix as a model of the unstructured part of the string landscape. The dynamical evolution in such a random potential from a small-field inflation region towards a viable late-time de Sitter (dS) minimum maps to the dynamics of Dyson Brownian motion describing the relaxation of non-equilibrium eigenvalue spectra in random matrix theory. We analytically compute the relaxation probability in a saddle point approximation of the partition function of the eigenvalue distribution of the Wigner ensemble describing the mass matrices of the critical points. When applied to small-field inflation in the landscape, this leads to an exponentially strong bias against small-field ranges and an upper bound N<<10 on the number of light fields N participating during inflation from the non-observation of negative spatial curvature.

Inflation with a graceful exit in a random landscape

Energy Technology Data Exchange (ETDEWEB)

Pedro, F.G. [Univ. Autonoma de Madrid (Spain). Dept. de Fisica Teorica y Inst. de Fisica Teorica UAM/CSIC; Westphal, A. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Theory Group

2016-11-15

We develop a stochastic description of small-field inflationary histories with a graceful exit in a random potential whose Hessian is a Gaussian random matrix as a model of the unstructured part of the string landscape. The dynamical evolution in such a random potential from a small-field inflation region towards a viable late-time de Sitter (dS) minimum maps to the dynamics of Dyson Brownian motion describing the relaxation of non-equilibrium eigenvalue spectra in random matrix theory. We analytically compute the relaxation probability in a saddle point approximation of the partition function of the eigenvalue distribution of the Wigner ensemble describing the mass matrices of the critical points. When applied to small-field inflation in the landscape, this leads to an exponentially strong bias against small-field ranges and an upper bound N<<10 on the number of light fields N participating during inflation from the non-observation of negative spatial curvature.

Inflation with a graceful exit in a random landscape

Energy Technology Data Exchange (ETDEWEB)

Pedro, F.G. [Departamento de Física Teórica and Instituto de Física Teórica UAM/CSIC,Universidad Autónoma de Madrid,Cantoblanco, 28049 Madrid (Spain); Westphal, A. [Deutsches Elektronen-Synchrotron DESY, Theory Group,D-22603 Hamburg (Germany)

2017-03-30

We develop a stochastic description of small-field inflationary histories with a graceful exit in a random potential whose Hessian is a Gaussian random matrix as a model of the unstructured part of the string landscape. The dynamical evolution in such a random potential from a small-field inflation region towards a viable late-time de Sitter (dS) minimum maps to the dynamics of Dyson Brownian motion describing the relaxation of non-equilibrium eigenvalue spectra in random matrix theory. We analytically compute the relaxation probability in a saddle point approximation of the partition function of the eigenvalue distribution of the Wigner ensemble describing the mass matrices of the critical points. When applied to small-field inflation in the landscape, this leads to an exponentially strong bias against small-field ranges and an upper bound N≪10 on the number of light fields N participating during inflation from the non-observation of negative spatial curvature.

Evaluation of multiple satellite evaporation products in two dryland regions using GRACE

KAUST Repository

Lopez, Oliver

2015-12-01

Remote sensing has become a valuable tool for monitoring the water cycle variables in areas that lack the availability of ground-based measurements. Integrating multiple remote sensing-based estimates of evaporation, precipitation, and the terrestrial water storage changes with local measurements of streamflow into a consistent estimate of the regional water budget is a challenge, due to the scale mismatch among the retrieved variables. Evapotranspiration, including soil evaporation, interception losses and canopy transpiration, has received special focus in a number of recent studies that aim to provide global or regional estimates of evaporation at regular time intervals using a variety of remote sensing input. In arid and semi-arid regions, modeling of evaporation is particularly challenging due to the relatively high role of the soil evaporation component in these regions and the variable nature of rainfall events that drive the evaporation process. In this study, we explore the hydrological consistency of remote sensing products in terms of water budget closure and the correlation among spatial patterns of precipitation (P), evaporation (E) and terrestrial water storage, using P-E as a surrogate of water storage changes, with special attention to the evaporation component. The analysis is undertaken within two dryland regions that have presented recent significant changes in climatology (Murray-Darling Basin in Australia) and water storage (the Saq aquifer in northern Saudi Arabia). Water storage changes were derived from the Gravity Recovery and Climate Experiment (GRACE) spherical harmonic (SH) coefficients. Six remote sensing-based evaporation estimates were subtracted from the Global Precipitation Climatology Project (GPCP)-based precipitation estimates and were compared with GRACE-derived water storage changes. Our results suggest that it is not possible to close the water balance by using satellite data alone, even when adopting a spherical harmonic

Crossing borders: displacement and the constitution od subjectivity in "Alias Grace", by Margaret Atwood

Directory of Open Access Journals (Sweden)

Thiago M. Moyano

2018-04-01

Full Text Available ABSTRACT: In the poststructuralist turn, a less unified and universalizing concept of space as merely a meaningless stage is proposed. Such notion, as Michel Foucault announced in the 1970s, will no longer be perceived by its fixity or a simply referential aspect, acquiring, among different forums of discussion in the Humanities, a dynamic character. In parallel fashion, studies concerning the constitution of subjectivity point towards its oscillating status, showing how the subject is the product of multiple discourses, which makes any demarcating of solid frontiers, a hard task. The present work aims at analyzing the novel Alias Grace (1996 by Margaret Atwood, under the light of spatial criticism, as well as Gender theory, deconstructing essentialisms around women. In this novel, Atwood gives voice to the historical figure Grace Marks, young Irish immigrant in the XIX century, which becomes mentor and accomplice of the murder of her employer, Thomas Kinnear, and his mistress and governess of the house, Nancy Montgomery. The author constructs a self-aware character-narrator who will know how to manipulate, through language, the many contexts in which she finds herself in, reversing the hierarchy of discourse, re-signifying her allegedly inferior position. Works by Philip Wegner and Neil Smith around the notion of space, Lorna McLean and Marilyn Barber about the Irish immigration in Canada, as well as Linda Hutcheon, Chris Weedon, and Jane Flax’s theories will be the theoretical apparatus of this investigation. KEYWORDS: Gender, Space, Post-colonialism, Margaret Atwood. __________________________________ RESUMO: A guinada Pós-estruturalista de meados do século XX propôs uma visão menos unificada e universalizante do conceito de espaço, este visto anteriormente como um mero cenário. Tal noção, conforme prenunciava Foucault nos anos 1970, não mais será compreendida por sua fixidez ou valor referencial, adquirindo, nos mais variados f

Co-Seismic Gravity Gradient Changes of the 2006-2007 Great Earthquakes in the Central Kuril Islands from GRACE Observations

Science.gov (United States)

Rahimi, A.; Shahrisvand, M.

2017-09-01

GRACE satellites (the Gravity Recovery And climate Experiment) are very useful sensors to extract gravity anomalies after earthquakes. In this study, we reveal co-seismic signals of the two combined earthquakes, the 2006 Mw8.3 thrust and 2007 Mw8.1 normal fault earthquakes of the central Kuril Islands from GRACE observations. We compute monthly full gravitational gradient tensor in the local north-east-down frame for Kuril Islands earthquakes without spatial averaging and de-striping filters. Some of gravitational gradient components (e.g. ΔVxx, ΔVxz) enhance high frequency components of the earth gravity field and reveal more details in spatial and temporal domain. Therefore, co-seismic activity can be better illustrated. For the first time, we show that the positive-negative-positive co-seismic ΔVxx due to the Kuril Islands earthquakes ranges from - 0.13 to + 0.11 milli Eötvös, and ΔVxz shows a positive-negative-positive pattern ranges from - 0.16 to + 0.13 milli Eötvös, agree well with seismic model predictions.

Assessment of the hydrologic setting and mass transport within Saharan and Arabian Aquifers using GRACE, geochemical, geophysical and subsurface data

Science.gov (United States)

Sultan, M.; Sturchio, N. C.; Ahmed, M.; Saleh, S.; Mohamed, A.; Abuabdullah, M. M.; Emil, M. K.; Bettadpur, S. V.; Save, H.; Fathy, K.; Chouinard, K.

2016-12-01

A better understanding of the hydrologic setting, mass transport, origin, evolution, utilization, sustainability, and paleo-climatic recharge conditions of Saharan and Arabian aquifers was achieved by integrating observation from monthly (04/2002 to 03/2016) Gravity Recovery and Climate Experiment (GRACE)-derived Terrestrial Water Storage (TWS) from multiple GRACE solutions (mascons and spherical harmonic fields) with others from geochemical (solute chemistry), isotopic (O, H, Sr), geochronologic (Chlorine-36, Krypton-81), geophysical (aerogravity and aeromagnetic), and subsurface data. The investigated aquifers are: (1) Nubian Sandstone Aquifer System (NSAS; area: 2×106 km2) in northeast Africa and, (2) Mega Aquifer System (MAS; area: 1.1×106 km2) in Arabia. Our findings indicate the NSAS and MAS were largely recharged in previous wet climatic Pleistocene periods, as evidenced by the groundwater ages (up to 1 million years), yet they receive modest local recharge during interleaving dry periods in areas of relatively high (≥ 20 mm/yr) precipitation. In Sudan and Chad (southern NSAS), the average annual precipitation (AAP) is 95 mm/yr and the recharge is estimated at 3.2 x 109 m3/yr ( 7% of AAP); in the southwest parts of the MAS, the recharge at the foothills of the Red Sea mountains is 1.8 x 109 m3/yr (10% of AAP). Uplifts and/or shear zones orthogonal to groundwater flow impede the south to north flow in the NSAS as evidenced by the large differences in GRACE-derived TWS trends, groundwater ages, and isotopic compositions on either side of the east-west trending Uweinat-Aswan uplift. Similarly west to east groundwater flow in the MAS is impeded and impounded up-gradient from the N-S and/or NW-SE trending basement structures, reactivated during Red Sea opening. Shear zones subparallel to groundwater flow act as preferred flow pathways, as is the case with the NE-SW trending Pelusium shear zone which channels groundwater from the Kufra sub-basin (Libya

26 CFR 5.856-1 - Extensions of the grace period for foreclosure property by a real estate investment trust.

Science.gov (United States)

2010-04-01

... 26 Internal Revenue 14 2010-04-01 2010-04-01 false Extensions of the grace period for foreclosure property by a real estate investment trust. 5.856-1 Section 5.856-1 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY (CONTINUED) INCOME TAX (CONTINUED) TEMPORARY INCOME TAX REGULATIONS UNDER THE REVENUE ACT OF 1978 § 5.856-1...

Monitoring the spatio-temporal changes of terrestrial water storage using GRACE data in the Tarim River basin between 2002 and 2015.

Science.gov (United States)

Yang, Peng; Xia, Jun; Zhan, Chesheng; Qiao, Yunfeng; Wang, Yueling

2017-10-01

With the threat of water shortages intensifying, the need to identify the terrestrial water storage (TWS) variation in the Tarim River Basin (TRB) becomes very significant for managing its water resource. Due to the lack of large-scale hydrological data, this study employed the Gravity Recovery and Climate Experiment (GRACE) and Global Land Data Assimilation System (GLDAS) to monitor TWS variation in the TRB during the period of 2002-2015, cooperating with two statistical techniques, Principal Component Analysis (PCA) - Empirical Orthogonal Function (EOF) and Multiple Linear Regression (MLR). Results indicated that (1) the Tropical rainfall measuring mission (TRMM) data can be applied well in the TRB; (2) the EOF result showed that both the time series of TRMM precipitation and GRACE-derived TWS in the TRB between 2002 and 2015 were dominated by the annual signals, which were followed by the semiannual signals; (3) the linear trend for the spatially averaged GRACE-derived TWS changes exhibited an decrease of 1.6±1.1mm/a, and the EOF result indicated a significant decrease of 4.1±1.5mm/a in the north of TRB; (4) while the precipitation variations was the major driver for the TWS changes, the GLDAS-derived TWS (i.e., soil moisture) decrease and ground water decrease played the major role in the TWS decrease in the north of TRB for the significant correlation (P<0.05). The changes of TWS might be linked to excessive exploitation of water resources, increased population, and shrinking water supplies, which would impact on the water level of the lakes or reservoir. Copyright © 2017 Elsevier B.V. All rights reserved.

Uncertainty estimates of a GRACE inversion modelling technique over Greenland using a simulation

Science.gov (United States)

Bonin, Jennifer; Chambers, Don

2013-07-01

The low spatial resolution of GRACE causes leakage, where signals in one location spread out into nearby regions. Because of this leakage, using simple techniques such as basin averages may result in an incorrect estimate of the true mass change in a region. A fairly simple least squares inversion technique can be used to more specifically localize mass changes into a pre-determined set of basins of uniform internal mass distribution. However, the accuracy of these higher resolution basin mass amplitudes has not been determined, nor is it known how the distribution of the chosen basins affects the results. We use a simple `truth' model over Greenland as an example case, to estimate the uncertainties of this inversion method and expose those design parameters which may result in an incorrect high-resolution mass distribution. We determine that an appropriate level of smoothing (300-400 km) and process noise (0.30 cm2 of water) gets the best results. The trends of the Greenland internal basins and Iceland can be reasonably estimated with this method, with average systematic errors of 3.5 cm yr-1 per basin. The largest mass losses found from GRACE RL04 occur in the coastal northwest (-19.9 and -33.0 cm yr-1) and southeast (-24.2 and -27.9 cm yr-1), with small mass gains (+1.4 to +7.7 cm yr-1) found across the northern interior. Acceleration of mass change is measurable at the 95 per cent confidence level in four northwestern basins, but not elsewhere in Greenland. Due to an insufficiently detailed distribution of basins across internal Canada, the trend estimates of Baffin and Ellesmere Islands are expected to be incorrect due to systematic errors caused by the inversion technique.

On the origins of Earth rotation anomalies: New insights on the basis of both “paleogeodetic” data and Gravity Recovery and Climate Experiment (GRACE) data

Science.gov (United States)

Peltier, W. R.; Luthcke, Scott B.

2009-11-01

The theory previously developed to predict the impact on Earth's rotational state of the late Pleistocene glaciation cycle is extended. In particular, we examine the extent to which a departure of the infinite time asymptote of the viscoelastic tidal Love number of degree 2, "k2T," from the observed "fluid" Love number, "kf," impacts the theory. A number of tests of the influence of the difference in these Love numbers on theoretical predictions of the model of the glacial isostatic adjustment (GIA) process are explored. Relative sea level history predictions are shown not to be sensitive to the difference even though they are highly sensitive to the influence of the changing rotational state itself. We also explore in detail the accuracy with which the Gravity Recovery and Climate Experiment (GRACE) satellite system is able to observe the global GIA process including the time-dependent amplitude of the degree 2 and order 1 spherical harmonic components of the gravitational field, the only components that are significantly influenced by rotational effects. It is explicitly shown that the GRACE observation of these properties of the time-varying gravitational field is sufficiently accurate to rule out the values predicted by the ICE-5G (VM2) model of Peltier (2004). However, we also note that this model is constrained only by data from an epoch during which modern greenhouse gas induced melting of both the great polar ice-sheets and small ice sheets and glaciers was not occurring. Such modern loss of grounded continental ice strongly influences the evolving rotational state of the planet and thus the values of the degree 2 and order 1 Stokes coefficients as they are currently being measured by the GRACE satellite system. A series of sensitivity tests are employed to demonstrate this fact. We suggest that the accuracy of scenarios for modern land ice melting may be tested by ensuring that such scenarios conform to the GRACE observations of these crucial time

Groundwater Depletion and the Sharp Increase of Seismicity in the Southern States, How GRACE Data Could Help?

Science.gov (United States)

Hong, Z.; Hasan, E.; Hong, Y.; Xia, B.; Zhong, H.

2016-12-01

This study is a contribution to how NASA's Gravity Recovery and Climate Experiment (GRACE) data may be used to track anthropogenic related change in the groundwater in the Southern Great Plains (SGP) as well recently increased seismicity in the southern states. The SGP contains one of the most important groundwater aquifers in the United States, the Ogallala groundwater aquifer, which has been exploited since 1900. Meanwhile, the recent activities of oil and gas extraction from the unconventional shall reservoir systems has led to significantly increased groundwater withdrawal and injection of wastewater. Consequently, numerous induced fracture related earthquakes have been recorded in Oklahoma and Texas between 2002 and 2016 The current paper investigates the utility of GRACE data along with the Land Water Content (LWC) information from the Global Land Data Assimilation System (GLDAS) to monitor and track the groundwater changes in three southern states of SGP (Oklahoma, Texas and New Mexico). Additionally, the paper investigates links between active seismicity and the injection of the wastewater due to the oil and gas production. Using GRACE data yields unprecedented information about the inter-annual changes in the Total Water Storage (TWS) from 2002 to 2016 over SGP. The LWC data set sums the soil moisture records with the the total canopy water storage to reveal the total land surface water content. The arithmetic difference between the TWS and LWC is the Groundwater Anomaly (GWA) for any particular region. In the current study, the GWA analysis reveals the following: (1) statistically significant drop of the GWA of about - 27 mm from 2002 to 2007 due to natural and anthropogenic causes; (2) the increased precipitation records from 2008 to 2011 over SGP leads to significant recovery in TWS and an increase in the groundwater content of about 40 mm; (3) the period from 2012 to 2015 experienced increased GWA of about - 6 mm for the period. Using the available

Antoine Ó Flatharta’s Elviad: from Grásta i Meiriceá to Grace in America

OpenAIRE

John L. Murphy

2006-01-01

Antoine Ó Flatharta bilingually charts media-saturated global impacts upon Galway’s Gaelic-speakers. His play in Irish,Grásta i Meiriceá (1990) features two young Irishmen who journey by bus on a pilgrimage to Elvis’ Graceland. In its 1993 English adaptation, Grace in America, the pair meets relatives who emigrated to 1940s Buffalo. Reading these plays by applying Seamus Deane’s “primordial nomination,” Edward Said’s “cartographical impulse,” Declan Kiberd’s “spiritual tourism,” and socioling...

Effect of Numerical Error on Gravity Field Estimation for GRACE and Future Gravity Missions

Science.gov (United States)

McCullough, Christopher; Bettadpur, Srinivas

2015-04-01

In recent decades, gravity field determination from low Earth orbiting satellites, such as the Gravity Recovery and Climate Experiment (GRACE), has become increasingly more effective due to the incorporation of high accuracy measurement devices. Since instrumentation quality will only increase in the near future and the gravity field determination process is computationally and numerically intensive, numerical error from the use of double precision arithmetic will eventually become a prominent error source. While using double-extended or quadruple precision arithmetic will reduce these errors, the numerical limitations of current orbit determination algorithms and processes must be accurately identified and quantified in order to adequately inform the science data processing techniques of future gravity missions. The most obvious numerical limitation in the orbit determination process is evident in the comparison of measured observables with computed values, derived from mathematical models relating the satellites' numerically integrated state to the observable. Significant error in the computed trajectory will corrupt this comparison and induce error in the least squares solution of the gravitational field. In addition, errors in the numerically computed trajectory propagate into the evaluation of the mathematical measurement model's partial derivatives. These errors amalgamate in turn with numerical error from the computation of the state transition matrix, computed using the variational equations of motion, in the least squares mapping matrix. Finally, the solution of the linearized least squares system, computed using a QR factorization, is also susceptible to numerical error. Certain interesting combinations of each of these numerical errors are examined in the framework of GRACE gravity field determination to analyze and quantify their effects on gravity field recovery.

Water Availability in the Tigris-Euphrates River Basin and the Middle East from GRACE

Science.gov (United States)

Voss, K.; Famiglietti, J. S.; Lo, M.; de Linage, C.; Swenson, S. C.; Rodell, M.

2010-12-01

As water security becomes more tenuous, conflicts and disputes over the appropriate management and allocation of transboundary water resources are sure to arise. In particular, the Middle East faces extreme scarcity as a result of both natural climate variations and the impacts of water management decisions and policies. A recent drought, which began in 2007, caused regional hardships as precious water resources dwindled and collaboration between nations failed to accommodate shared needs. In this work, the area surrounding the Tigris and Euphrates River Basin was selected as a case study to evaluate trends in fresh water availability. Because few complete datasets exist for precipitation, streamflow, evapotranspiration, groundwater or surface water in the area, remote sensing techniques, including GRACE and altimetry, as well as land-surface models were utilized to develop an understanding of the regional hydrology. These observations and model results were used to estimate trends in total water storage and its individual components - soil moisture, snow water equivalent, surface water and groundwater. GRACE data show a clear decrease in total water storage in the Middle East from January 2003 to December 2009, and indicate that the selected region experienced a total volume loss of 143 km3 of water. Supporting datasets suggest that approximately two-thirds of this was a loss of groundwater. These results highlight the impacts of drought conditions on groundwater consumption and of agricultural expansion on available water resources in the region. Furthermore, they raise important political issues regarding water use in transboundary river basins and aquifers, while amplifying the need for increased monitoring and datasets for the core components of the water budget.

Antarctic Mass Loss from GRACE from Space- and Time-Resolved Modeling with Slepian Functions

Science.gov (United States)

Simons, F. J.; Harig, C.

2013-12-01

The melting of polar ice sheets is a major contributor to global sea-level rise. Antarctica is of particular interest since most of the mass loss has occurred in West Antarctica, however updated glacial isostatic adjustment (GIA) models and recent mass gains in East Antarctica have reduced the continent-wide integrated decadal trend of mass loss. Here we present a spatially and temporally resolved estimation of the Antarctic ice mass change using Slepian localization functions. With a Slepian basis specifically for Antarctica, the basis functions maximize their energy on the continent and we can project the geopotential fields into a sparse set of orthogonal coefficients. By fitting polynomial functions to the limited basis coefficients we maximize signal-to-noise levels and need not perform smoothing or destriping filters common to other approaches. In addition we determine an empirical noise covariance matrix from the GRACE data to estimate the uncertainty of mass estimation. When applied to large ice sheets, as in our own recent Greenland work, this technique is able to resolve both the overall continental integrated mass trend, as well as the spatial distribution of the mass changes over time. Using CSR-RL05 GRACE data between Jan. 2003 and Jan 2013, we estimate the regional accelerations in mass change for several sub-regions and examine how the spatial pattern of mass has changed. The Amundsen Sea coast of West Antarctica has experienced a large acceleration in mass loss (-26 Gt/yr^2). While mass loss is concentrated near Pine Island and Thwaites glaciers, it has also increased along the coast further towards the Ross ice shelf.

Greenland inland ice melt-off: Analysis of global gravity data from the GRACE satellites

DEFF Research Database (Denmark)

Nielsen, Allan Aasbjerg; Andersen, Ole Baltazar; Svendsen, Peter L.

2011-01-01

This paper gives an introductory analysis of gravity data from the GRACE (Gravity Recovery And Climate Experiment) twin satellites. The data consist of gravity data in the form of 10-day maximum values of 1◦ by 1◦ equivalent water height (EWH) in meters starting at 29 July 2002 and ending at 25...... August 2010. Results focussing on Greenland show statistically significant mass loss interpreted as inland ice melt-off to the SE and NW with an acceleration in the melt-off occurring to the NW and a possible deceleration to the SE. Also, there are strong indications of a transition taking place...

Antarctica, Greenland and Gulf of Alaska Land-Ice Evolution from an Iterated GRACE Global Mascon Solution

Science.gov (United States)

Luthcke, Scott B.; Sabaka, T. J.; Loomis, B. D.; Arendt, A. A.; McCarthy, J. J.; Camp, J.

2013-01-01

We have determined the ice mass evolution of the Antarctica and Greenland ice sheets (AIS and GIS) and Gulf of Alaska (GOA) glaciers from a new GRACE global solution of equal-area surface mass concentration parcels (mascons) in equivalent height of water. The mascons were estimated directly from the reduction of the inter-satellite K-band range-rate (KBRR) observations, taking into account the full noise covariance, and formally iterating the solution. The new solution increases signal recovery while reducing the GRACE KBRR observation residuals. The mascons were estimated with 10 day and 1 arc degree equal-area sampling, applying anisotropic constraints. An ensemble empirical mode decomposition adaptive filter was applied to the mascon time series to compute annual mass balances. The details and causes of the spatial and temporal variability of the land-ice regions studied are discussed. The estimated mass trend over the total GIS, AIS and GOA glaciers for the time period 1 December 2003 to 1 December 2010 is -380 plus or minus 31 Gt a(exp -1), equivalent to -1.05 plus or minus 0.09 mma(exp -1) sea-level rise. Over the same time period we estimate the mass acceleration to be -41 plus or minus 27 Gt a(exp -2), equivalent to a 0.11 plus or minus 0.08 mm a(exp -2) rate of change in sea level. The trends and accelerations are dependent on significant seasonal and annual balance anomalies.

Diagnostic Value of Subjective Memory Complaints Assessed with a Single Item in Dominantly Inherited Alzheimer’s Disease: Results of the DIAN Study

Directory of Open Access Journals (Sweden)

Christoph Laske

2015-01-01

Full Text Available Objective. We examined the diagnostic value of subjective memory complaints (SMCs assessed with a single item in a large cross-sectional cohort consisting of families with autosomal dominant Alzheimer’s disease (ADAD participating in the Dominantly Inherited Alzheimer Network (DIAN. Methods. The baseline sample of 183 mutation carriers (MCs and 117 noncarriers (NCs was divided according to Clinical Dementia Rating (CDR scale into preclinical (CDR 0; MCs: n=107; NCs: n=109, early symptomatic (CDR 0.5; MCs: n=48; NCs: n=8, and dementia stage (CDR ≥ 1; MCs: n=28; NCs: n=0. These groups were subdivided by the presence or absence of SMCs. Results. At CDR 0, SMCs were present in 12.1% of MCs and 9.2% of NCs (P=0.6. At CDR 0.5, SMCs were present in 66.7% of MCs and 62.5% of NCs (P=1.0. At CDR ≥ 1, SMCs were present in 96.4% of MCs. SMCs in MCs were significantly associated with CDR, logical memory scores, Geriatric Depression Scale, education, and estimated years to onset. Conclusions. The present study shows that SMCs assessed by a single-item scale have no diagnostic value to identify preclinical ADAD in asymptomatic individuals. These results demonstrate the need of further improvement of SMC measures that should be examined in large clinical trials.

A reading list for Bill Gates--and you. A conversation with literary critic Harold Bloom. Interview by Diane L. Coutu.

Science.gov (United States)

Bloom, H

2001-05-01

In today's technology-driven world, who has time to pick up a 400-page novel? Most executives don't--they have urgent e-mails to answer, training seminars to attend, meetings to lead, and trade publications to scan. But according to Harold Bloom, one of America's most influential scholars, they should make time in their hectic schedules to read great works. In a wide-ranging conversation with HBR senior editor Diane Coutu, Bloom discusses the importance of literature: every individual--regardless of profession--needs to stretch his or her mind and reflect now and again on the human condition. "By reading great imaginative literature, you can prepare yourself for surprise and even get a kind of strength that welcomes and exploits the unexpected," he says. Because there are so many great works and there is so little time, Bloom presents a reading list for busy executives. Shakespeare's King Lear can teach businesspeople about change. Ralph Waldo Emerson's essays capture the ethos of the American spirit--individualism and inventiveness. Bloom says Sigmund Freud's conceptions "form the only Western mythology that contemporary intellectuals have in common." And people will never fully understand some aspects of themselves until they read Miguel de Cervantes's Don Quixote. In short, Bloom believes the humanities have much to offer businesspeople: great books broaden their awareness and their range of sensibility, he says. But reading literature will not make businesspeople more moral, he cautions. Bloom also discusses other topics such as how to read well, the state of popular fiction, the role of irony, and the subject of change.

Past terrestrial water storage (1980–2008 in the Amazon Basin reconstructed from GRACE and in situ river gauging data

Directory of Open Access Journals (Sweden)

M. Becker

2011-02-01

Full Text Available Terrestrial water storage (TWS composed of surface waters, soil moisture, groundwater and snow where appropriate, is a key element of global and continental water cycle. Since 2002, the Gravity Recovery and Climate Experiment (GRACE space gravimetry mission provides a new tool to measure large-scale TWS variations. However, for the past few decades, direct estimate of TWS variability is accessible from hydrological modeling only. Here we propose a novel approach that combines GRACE-based TWS spatial patterns with multi-decadal-long in situ river level records, to reconstruct past 2-D TWS over a river basin. Results are presented for the Amazon Basin for the period 1980–2008, focusing on the interannual time scale. Results are compared with past TWS estimated by the global hydrological model ISBA-TRIP. Correlations between reconstructed past interannual TWS variability and known climate forcing modes over the region (e.g., El Niño-Southern Oscillation and Pacific Decadal Oscillation are also estimated. This method offers new perspective for improving our knowledge of past interannual TWS in world river basins where natural climate variability (as opposed to direct anthropogenic forcing drives TWS variations.

GRACE-Based Analysis of Total Water Storage Trends and Groundwater Fluctuations in the North-Western Sahara Aquifer System (NWSAS) and Tindouf Aquifer in Northwest Africa

Science.gov (United States)

Lezzaik, K. A.; Milewski, A.

2013-12-01

Optimal water management practices and strategies, in arid and semi-arid environments, are often hindered by a lack of quantitative and qualitative understanding of hydrological processes. Moreover, progressive overexploitation of groundwater resources to meet agricultural, industrial, and domestic requirements is drawing concern over the sustainability of such exhaustive abstraction levels, especially in environments where groundwater is a major source of water. NASA's GRACE (gravity recovery and climate change experiment) mission, since March 2002, has advanced the understanding of hydrological events, especially groundwater depletion, through integrated measurements and modeling of terrestrial water mass. In this study, GLDAS variables (rainfall rate, evapotranspiration rate, average soil moisture), and TRMM 3B42.V7A precipitation satellite data, were used in combination with 95 GRACE-generated gravitational anomalies maps, to quantify total water storage change (TWSC) and groundwater storage change (GWSC) from January 2003 to December 2010 (excluding June 2003), in the North-Western Sahara Aquifer System (NWSAS) and Tindouf Aquifer System in northwestern Africa. Separately processed and computed GRACE products by JPL (Jet Propulsion Laboratory, NASA), CSR (Center of Space Research, UT Austin), and GFZ (German Research Centre for Geoscience, Potsdam), were used to determine which GRACE dataset(s) best reflect total water storage and ground water changes in northwest Africa. First-order estimates of annual TWSC for NWSAS (JPL: +5.297 BCM; CSR: -5.33 BCM; GFZ: -9.96 BCM) and Tindouf Aquifer System (JPL: +1.217 BCM; CSR: +0.203 BCM; GFZ: +1.019 BCM), were computed using zonal averaging over a span of eight years. Preliminary findings of annual GWSC for NWSAS (JPL: +2.45 BCM; CSR: -2.278 BCM; GFZ: -6.913 BCM) and Tindouf Aquifer System (JPL: +1.108 BCM; CSR: +0.094 BCM; GFZ: +0.910 BCM), were calculating using a water budget approach, parameterized by GLDAS

Temporal and spatial variabilities of Antarctic ice mass changes inferred by GRACE in a Bayesian framework

Science.gov (United States)

Wang, L.; Davis, J. L.; Tamisiea, M. E.

2017-12-01

The Antarctic ice sheet (AIS) holds about 60% of all fresh water on the Earth, an amount equivalent to about 58 m of sea-level rise. Observation of AIS mass change is thus essential in determining and predicting its contribution to sea level. While the ice mass loss estimates for West Antarctica (WA) and the Antarctic Peninsula (AP) are in good agreement, what the mass balance over East Antarctica (EA) is, and whether or not it compensates for the mass loss is under debate. Besides the different error sources and sensitivities of different measurement types, complex spatial and temporal variabilities would be another factor complicating the accurate estimation of the AIS mass balance. Therefore, a model that allows for variabilities in both melting rate and seasonal signals would seem appropriate in the estimation of present-day AIS melting. We present a stochastic filter technique, which enables the Bayesian separation of the systematic stripe noise and mass signal in decade-length GRACE monthly gravity series, and allows the estimation of time-variable seasonal and inter-annual components in the signals. One of the primary advantages of this Bayesian method is that it yields statistically rigorous uncertainty estimates reflecting the inherent spatial resolution of the data. By applying the stochastic filter to the decade-long GRACE observations, we present the temporal variabilities of the AIS mass balance at basin scale, particularly over East Antarctica, and decipher the EA mass variations in the past decade, and their role in affecting overall AIS mass balance and sea level.

Approach of regional gravity field modeling from GRACE data for improvement of geoid modeling for Japan

Science.gov (United States)

Kuroishi, Y.; Lemoine, F. G.; Rowlands, D. D.

2006-12-01

The latest gravimetric geoid model for Japan, JGEOID2004, suffers from errors at long wavelengths (around 1000 km) in a range of +/- 30 cm. The model was developed by combining surface gravity data with a global marine altimetric gravity model, using EGM96 as a foundation, and the errors at long wavelength are presumably attributed to EGM96 errors. The Japanese islands and their vicinity are located in a region of plate convergence boundaries, producing substantial gravity and geoid undulations in a wide range of wavelengths. Because of the geometry of the islands and trenches, precise information on gravity in the surrounding oceans should be incorporated in detail, even if the geoid model is required to be accurate only over land. The Kuroshio Current, which runs south of Japan, causes high sea surface variability, making altimetric gravity field determination complicated. To reduce the long-wavelength errors in the geoid model, we are investigating GRACE data for regional gravity field modeling at long wavelengths in the vicinity of Japan. Our approach is based on exclusive use of inter- satellite range-rate data with calibrated accelerometer data and attitude data, for regional or global gravity field recovery. In the first step, we calibrate accelerometer data in terms of scales and biases by fitting dynamically calculated orbits to GPS-determined precise orbits. The calibration parameters of accelerometer data thus obtained are used in the second step to recover a global/regional gravity anomaly field. This approach is applied to GRACE data obtained for the year 2005 and resulting global/regional gravity models are presented and discussed.

Terrestrial Water Storage from GRACE and Satellite Altimetry in the Okavango Delta (Botswana)

DEFF Research Database (Denmark)

Andersen, Ole Baltazar; Krogh, Pernille Engelbredt; Bauer-Gottwein, Peter

2010-01-01

New technology can for the first time enable the accurate retrieval of the global and regional water budgets from space-borne and ground-based gravity surveys. Water is mankind’s most critical natural resource, but it is being heavily used throughout the globe. The aim of this paper is to outline...... the HYDROGRAV project dealing with improving large scale hydrological model with time variable gravity observations. Also preliminary HYDROGRAV investigationsa of terrestrial water storage variations in the Okavango delta in Botswana are presented. Data from 4 years of satellite altimetry, GRACE derived TWS...... and GLDAS hydrological model all show a clear annual variation corresponding to the well known seasonality of the delta. However, they also all show an increasing trend in the amount of water storage in the region over the last 4 years....

Antarctic Glacial Isostatic Adjustment and Ice Sheet Mass Balance using GRACE: A Report from the Ice-sheet Mass Balance Exercise (IMBIE)

Science.gov (United States)

Ivins, E. R.; Wahr, J. M.; Schrama, E. J.; Milne, G. A.; Barletta, V.; Horwath, M.; Whitehouse, P.

2012-12-01

In preparation for the Inter-govermental Panel on Climate Change: Assessment Report 5 (IPCC AR5), ESA and NASA have formed a committee of experts to perform a formal set of comparative experiments concerning space observations of ice sheet mass balance. This project began in August of 2011 and has now concluded with a report submitted for Science (Shepherd et al., 2012). The focus of the work conducted is to re-evaluate scientific reports on the mass balance of Greenland ice sheet (GIS) and Antarctic ice sheet (AIS). The most serious discrepancies have been reported for the AIS, amounting to as much as 0.9 mm/yr in discrepant sea level contribution. A direct method of determining the AIS is by space gravimetry. However, for this method to contribute to our understanding of sea level change, we require knowledge of present-day non-elastic vertical movements of bedrock in Antarctica. Quantifying the uncertainty and bias caused by lack of observational control on models of regional glacial isostatic adjustment (GIA), was a major focus for our experiments. This regional process is the most problematic error source for GRACE-determinations of ice mass balance in Antarctica. While GIA likely dominates some large vertical motions in Antarctica that are now observed with GPS (Thomas et al., 2011, GRL), interpretations still require models. The reported uncertainty for space gravimetric (GRACE) based sea level sourcing is roughly 0.20 to 0.35 mm/yr. The uncertainty is also part of the error budget for mass balances derived from altimetry measurements, though at a much lower level. Analysis of the GRACE time series using CSR RL04 (2003.0-2010.10) for AIS mass balance reveals a small trend of order +1 to -24 Gt/yr without a GIA correction. Three periods were selected over which to perform inter-comparisons (see Table). One class of GIA models, that relies primarily on far field sea level reconstructions (e.g. ICE-5G), provide a GIA correction that places AIS mass imbalance (�

Global seasonal strain and stress models derived from GRACE loading, and their impact on seismicity

Science.gov (United States)

Chanard, K.; Fleitout, L.; Calais, E.; Craig, T. J.; Rebischung, P.; Avouac, J. P.

2017-12-01

Loading by continental water, atmosphere and oceans deforms the Earth at various spatio-temporal scales, inducing crustal and mantelic stress perturbations that may play a role in earthquake triggering.Deformation of the Earth by this surface loading is observed in GNSS position time series. While various models predict well vertical observations, explaining horizontal displacements remains challenging. We model the elastic deformation induced by loading derived from GRACE for coefficients 2 and higher. We estimate the degree-1 deformation field by comparison between predictions of our model and IGS-repro2 solutions at a globally distributed network of 700 GNSS sites, separating the horizontal and vertical components to avoid biases between components. The misfit between model and data is reduced compared to previous studies, particularly on the horizontal component. The associated geocenter motion time series are consistent with results derived from other datasets. We also discuss the impact on our results of systematic errors in GNSS geodetic products, in particular of the draconitic error.We then compute stress tensors time series induced by GRACE loads and discuss the potential link between large scale seasonal mass redistributions and seismicity. Within the crust, we estimate hydrologically induced stresses in the intraplate New Madrid Seismic Zone, where secular stressing rates are unmeasurably low. We show that a significant variation in the rate of micro-earthquakes at annual and multi-annual timescales coincides with stresses induced by hydrological loading in the upper Mississippi embayment, with no significant phase-lag, directly modulating regional seismicity. We also investigate pressure variations in the mantle transition zone and discuss potential correlations between the statistically significant observed seasonality of deep-focus earthquakes, most likely due to mineralogical transformations, and surface hydrological loading.

Mortality and cardiovascular morbidity within 30 days of discharge following acute coronary syndrome in a contemporary European cohort of patients: How can early risk prediction be improved? The six-month GRACE risk score.

Science.gov (United States)

Raposeiras-Roubín, Sergio; Abu-Assi, Emad; Cambeiro-González, Cristina; Álvarez-Álvarez, Belén; Pereira-López, Eva; Gestal-Romaní, Santiago; Pedreira-López, Milagros; Rigueiro-Veloso, Pedro; Virgós-Lamela, Alejandro; García-Acuña, José María; González-Juanatey, José Ramón

2015-06-01

Given the increasing focus on early mortality and readmission rates among patients with acute coronary syndrome (ACS), this study was designed to evaluate the accuracy of the GRACE risk score for identifying patients at high risk of 30-day post-discharge mortality and cardiovascular readmission. This was a retrospective study carried out in a single center with 4229 ACS patients discharged between 2004 and 2010. The study endpoint was the combination of 30-day post-discharge mortality and readmission due to reinfarction, heart failure or stroke. One hundred and fourteen patients had 30-day events: 0.7% mortality, 1% reinfarction, 1.3% heart failure, and 0.2% stroke. After multivariate analysis, the six-month GRACE risk score was associated with an increased risk of 30-day events (HR 1.03, 95% CI 1.02-1.04; p<0.001), demonstrating good discrimination (C-statistic: 0.79 ± 0.02) and optimal fit (Hosmer-Lemeshow p=0.83). The sensitivity and specificity were adequate (78.1% and 63.3%, respectively), and negative predictive value was excellent (99.1%). In separate analyses for each event of interest (all-cause mortality, reinfarction, heart failure and stroke), assessment of the six-month GRACE risk score also demonstrated good discrimination and fit, as well as adequate predictive values. The six-month GRACE risk score is a useful tool to predict 30-day post-discharge death and early cardiovascular readmission. Clinicians may find it simple to use with the online and mobile app score calculator and applicable to clinical daily practice. Copyright © 2014 Sociedade Portuguesa de Cardiologia. Published by Elsevier España. All rights reserved.

Impact of GPS antenna phase center and code residual variation maps on orbit and baseline determination of GRACE

Science.gov (United States)

Mao, X.; Visser, P. N. A. M.; van den IJssel, J.

2017-06-01

Precision Orbit Determination (POD) is a prerequisite for the success of many Low Earth Orbiting (LEO) satellite missions. With high-quality, dual-frequency Global Positioning System (GPS) receivers, typically precisions of the order of a few cm are possible for single-satellite POD, and of a few mm for relative POD of formation flying spacecraft with baselines up to hundreds of km. To achieve the best precision, the use of Phase Center Variation (PCV) maps is indispensable. For LEO GPS receivers, often a-priori PCV maps are obtained by a pre-launch ground campaign, which is not able to represent the real space-borne environment of satellites. Therefore, in-flight calibration of the GPS antenna is more widely conducted. This paper shows that a further improvement is possible by including the so-called Code Residual Variation (CRV) maps in absolute/undifferenced and relative/Double-differenced (DD) POD schemes. Orbit solutions are produced for the GRACE satellite formation for a four months test period (August-November, 2014), demonstrating enhanced orbit precision after first using the in-flight PCV maps and a further improvement after including the CRV maps. The application of antenna maps leads to a better consistency with independent Satellite Laser Ranging (SLR) and K-band Ranging (KBR) low-low Satellite-to-Satellite Tracking (ll-SST) observations. The inclusion of the CRV maps results also in a much better consistency between reduced-dynamic and kinematic orbit solutions for especially the cross-track direction. The improvements are largest for GRACE-B, where a cross-talk between the GPS main antenna and the occultation antenna yields higher systematic observation residuals. For high-precision relative POD which necessitates DD carrier-phase ambiguity fixing, in principle frequency-dependent PCV maps would be required. To this aim, use is made of an Extended Kalman Filter (EKF) that is capable of optimizing relative spacecraft dynamics and iteratively fixing

Reprezentace homosexuality v americkém sitcomu na příkladu Will a Grace a Taková moderní rodinka

OpenAIRE

Hofmanová, Zuzana

2017-01-01

The diploma theses "Representation of Homosexuality in American Sitcom, as exemplified by Will & Grace and Modern Family" examines the portrayal of minority groups on television. Initially vilified as perverts and abominations, homosexual individuals are now seen as complex characters that buck older stigmatization and stereotypes. These changes can be exemplified and documented across different popular genres currently on television. However, a sitcom is a genre defined by specific rules. Th...

Evapotranspiration Estimation over Yangtze River Basin from GRACE satellite measurement and in situ data

Science.gov (United States)

Li, Qiong; Luo, Zhicai; Zhong, Bo; Wang, Haihong; Zhou, Zebing

2016-04-01

As the critical component of hydrologic cycle, evapotranspiration (ET) plays an important role in global water exchanges and energy flow across the hydrosphere, atmosphere and biosphere. Influenced by the Asian monsoon, the Yangtze River Basin (YRB) suffer from the several severe floods and droughts over the last decades due to the significant difference between temporal and spatial distribution terrestrial water storages. As an indispensable part, it is practically important to assessment ET in the YRB accompany with increased population and rapid economic and agriculture development. Average ET over the YRB is computed as the residual of terrestrial water budget using the Gravity Recovery and Climate Experiment (GRACE) satellite-based measurements and the ground-based observations. The GRACE-based ET were well coincidence with the ET from MODIS, with the correlation coefficient of 0.853, and the correlation coefficient is 0.696 while comparing with the ET ground-based observation. The mean monthly average of ET from these various estimates is 56.9 mm/month over the whole YRB, and peak between June and August. Monthly variations of ET reach a maximum in Wujiang with 69.11 mm/month and a minimum in Jinshajiang with 39.01 mm/month. Based on the correlation between ET and independent estimates of near-surface temperature and soil moisture, it is showed that as the temperature increased, the ET of the seven sub-catchment were rising except for the Poyang Lake and Donting Lake. And we also can infer that the midstream of YRB is significant correlated with ESON especially in the Hanjiang basin. The Surface Humidity Index over the YRB was gradually decreased and its variations in each sub-catchment showed a significant decreasing trend in Jinshajiang and Mingjiang. This research has important potential for use in large-scale water budget assessments and intercomparison studies. Acknowledgements: This research is supported by the National Natural Science Foundation of

Characteristic precipitation patterns of El Niño/La Niña in time-variable gravity fields by GRACE

OpenAIRE

Morishita, Yu; Heki, Kosuke

2008-01-01

El Niño and La Niña are known to bring about characteristic patterns of anomalous precipitation in various regions of the world. We extracted temporary and regional gravity changes from monthly gravity fields recovered by the GRACE satellites, and converted them to the changes in surface mass, possibly ground or subsurface water in land area. Such mass changes in the 2006-2007 El Niño and 2005-2006 La Niña episodes agreed well with precipitation anomaly patterns inferred from meteorological r...

Gracing incidence small angle neutron scattering of incommensurate magnetic structures in MnSi thin films

Energy Technology Data Exchange (ETDEWEB)

Wiedemann, Birgit; Pfleiderer, Christian; Boeni, Peter [Physik Department, Technische Universitaet Muenchen (Germany); Zhang, Shilei; Hesjedal, Thorsten [Clarendon Laboratory, Department of Physics, University of Oxford (United Kingdom); Khaydukov, Yury; Soltwedel, Olaf; Keller, Thomas [Max-Planck-Institut fuer Festkoerperforschung (Germany); Max Planck Society, Outstation at FRM-II (Germany); Muehlbauer, Sebastian [Forschungsneutronenquelle Heinz Maier Leibnitz, Technische Universitaet Muenchen (Germany); Chacon, Alfonso [Physik Department, Technische Universitaet Muenchen (Germany); Forschungsneutronenquelle Heinz Maier Leibnitz, Technische Universitaet Muenchen (Germany)

2015-07-01

The topological stability of skyrmions in bulk samples of MnSi and the observation of spin transfer torque effects at ultra-low current densities have generated great interest in skyrmions in chiral magnets as a new route towards next generation spintronics devices. Yet, the formation of skyrmions in MBE grown thin films of MnSi reported in the literature is highly controversial. We report gracing incidence small angle neutron scattering (GISANS) of the magnetic order in selected thin films of MnSi grown by state of the art MBE techniques. In combination with polarised neutron reflectometry (PNR) and magnetisation measurements of the same samples our data provide direct reciprocal space information of the incommensurate magnetic order, clarifying the nature of magnetic phase diagram.

Integration of altimetric lake levels and GRACE gravimetry over Africa: Inferences for terrestrial water storage change 2003-2011

Science.gov (United States)

Moore, P.; Williams, S. D. P.

2014-12-01

Terrestrial water storage (TWS) change for 2003-2011 is estimated over Africa from GRACE gravimetric data. The signatures from change in water of the major lakes are removed by utilizing kernel functions with lake heights recovered from retracked ENVISAT satellite altimetry. In addition, the contribution of gravimetric change due to soil moisture and biomass is removed from the total GRACE signal by utilizing the GLDAS land surface model. The residual TWS time series, namely groundwater and the surface waters in rivers, wetlands, and small lakes, are investigated for trends and the seasonal cycle using linear regression. Typically, such analyses assume that the data are temporally uncorrelated but this has been shown to lead to erroneous inferences in related studies concerning the linear rate and acceleration. In this study, we utilize autocorrelation and investigate the appropriate stochastic model. The results show the proper distribution of TWS change and identify the spatial distribution of significant rates and accelerations. The effect of surface water in the major lakes is shown to contribute significantly to the trend and seasonal variation in TWS in the lake basin. Lake Volta, a managed reservoir in Ghana, is seen to have a contribution to the linear trend that is a factor of three greater than that of Lake Victoria despite having a surface area one-eighth of that of Lake Victoria. Analysis also shows the confidence levels of the deterministic trend and acceleration identifying areas where the signatures are most likely due to a physical deterministic cause and not simply stochastic variations.

In the Classroom.

Science.gov (United States)

French, Michael P.; Danielson, Kathy Everts

1990-01-01

Presents six reading and writing activities: "Details, Details, Details" (Rona F. Flippo and Judy Anderson Smith); "Reading and Writing Informational Texts" (Joyce Joranko); "The Teacher Writes: Before and for Children" (Ann Horn); "A School Newspaper: The Crown Press" (Judy Kissell); "Short Snappers…

Partitioning of the water budget in the main river basins in High Mountain Asia with GRACE, model output, and other observations.

Science.gov (United States)

Velicogna, I.; Ciraci, E.; Grogan, D. S.; Lammers, R. B.

2017-12-01

Access to freshwater is important as world populations grow, especially in High Mountain Asia, where glaciers are a significant component of the freshwater resources, particularly in summer. Glaciers are sensitive to climate perturbations and affected by climate change. Our understanding of the contribution of glacier runoff to specific watersheds, and projections of glacier runoff in a warming climate, are critical to inform decisions, management and policy development. Here, we quantify changes in glacier mass balance in HMA using GRACE data and determine their contribution to river basin hydrology. We use GRACE data to estimate the HMA glacier mass mas balance and compare the results with changes in total water storage (TWS) for the major watersheds in the HMA regions. We designed ad-hoc mascon configurations to calculate the upstream glacier change in mass balance and contribution to major river basins water supply, determined appropriate corrections and uncertainties for the signal and evaluated the results via comparison with the Water Balance Model (WBM) output and other data (re-analysis data and satellite-derived precipitation and evapotranspiration). Most of the glacier loss is from the Himalaya region (Himalaya, Hengduan Shan S and E Tibet), whereas the western sectors (E and W Tien Shan; and Hindu Kush, Karakoram, W Kunlun, Pamir, Hissar Alay) experienced smaller losses but with larger interannual variability driven by changes in the westerly-driven winter precipitation. For the Indus basin, to evaluate the glacier contribution to the total water budget, we examine the contribution of the upper basin to the lower basin TWS change. Over the Upper Indus basin, we find that the seasonal decline in total water storage between May and September averages 88 Gt during 2002-2012. TRMM cumulative precipitation amounts to 119 Gt, leaving a runoff and evapotranspiration component of 207 Gt. This estimate compares well with an estimate for the WBM modeled runoff of

Characterizing ecosystem response to water supply changes inferred from GRACE drought severity index and surface soil moisture anomalies from ESA CCI and SMAP

Science.gov (United States)

Zhao, M.; Velicogna, I.; Kimball, J. S.

2017-12-01

Climate change such as more frequent heatwaves and drought is threatening our food security and ecosystem by reducing water supply to vegetation. Characterizing vegetation response to water supply changes is not only important for evaluating and mitigating climatic change impacts on ecosystem functions and services, but also to determine the feedback mechanisms that ecosystem response may generate on the climate itself. However, such characterization is not well-known at the global scale partly because large scale observations of underground water supply changes are limited. Satellite observations of soil moisture (SM) datasets such as from Soil Moisture Active and Passive (SMAP) and European Space Agency Climate Change Initiative (ESA CCI) do not penetrate more than a few centimeters and do not capture the entire root-zone. Here we employ a newly developed Drought Severity Index from Gravity Recovery and Climate Experiment (GRACE-DSI) to complement SM observations by informing total water supply changes in the entire terrestrial hydrological cycle. We use MODIS vegetation indices as proxies for vegetation growth and investigate their seasonal and interannual variability in relation to GRACE-DSI. We find that total water supply constrains vegetation growth across the entire continental US. Water constraint begins at an earlier date of year and lasts for a longer period in the lower latitude than in the higher latitude. We also find that water constraint occurs at different phenological stages depending on vegetation type. For instance, water constrain forest growth during reproductive period in eastern US but constrain shrub land growth during green-up in Arizona (Fig. 1). In western United States, eastern Australia and the horn of Africa, we find that vegetation growth changes closely follows GRACE-DSI but can have 16-day to one-month delay with respect to SM anomalies from SMAP and ESA CCI. This suggests that in these regions, vegetation is sensitive to water

Optimizing estimates of annual variations and trends in geocenter motion and J2 from a combination of GRACE data and geophysical models

Science.gov (United States)

Sun, Yu; Riva, Riccardo; Ditmar, Pavel

2016-11-01

The focus of the study is optimizing the technique for estimating geocenter motion and variations in J2 by combining data from the Gravity Recovery and Climate Experiment (GRACE) satellite mission with output from an Ocean Bottom Pressure model and a Glacial Isostatic Adjustment (GIA) model. First, we conduct an end-to-end numerical simulation study. We generate input time-variable gravity field observations by perturbing a synthetic Earth model with realistically simulated errors. We show that it is important to avoid large errors at short wavelengths and signal leakage from land to ocean, as well as to account for self-attraction and loading effects. Second, the optimal implementation strategy is applied to real GRACE data. We show that the estimates of annual amplitude in geocenter motion are in line with estimates from other techniques, such as satellite laser ranging (SLR) and global GPS inversion. At the same time, annual amplitudes of C10 and C11 are increased by about 50% and 20%, respectively, compared to estimates based on Swenson et al. (2008). Estimates of J2 variations are by about 15% larger than SLR results in terms of annual amplitude. Linear trend estimates are dependent on the adopted GIA model but still comparable to some SLR results.

Ocean Bottom Pressure Seasonal Cycles and Decadal Trends from GRACE Release-05: Ocean Circulation Implications

Science.gov (United States)

Johnson, G. C.; Chambers, D. P.

2013-12-01

Ocean mass variations are important for diagnosing sea level budgets, the hydrological cycle and global energy budget, as well as ocean circulation variability. Here seasonal cycles and decadal trends of ocean mass from January 2003 to December 2012, both global and regional, are analyzed using GRACE Release 05 data. The trend of global flux of mass into the ocean approaches 2 cm decade-1 in equivalent sea level rise. Regional trends are of similar magnitude, with the North Pacific, South Atlantic, and South Indian oceans generally gaining mass and other regions losing mass. These trends suggest a spin-down of the North Pacific western boundary current extension and the Antarctic Circumpolar Current in the South Atlantic and South Indian oceans. The global average seasonal cycle of ocean mass is about 1 cm in amplitude, with a maximum in early October and volume fluxes in and out of the ocean reaching 0.5 Sv (1 Sv = 1 × 106 m3 s-1) when integrated over the area analyzed here. Regional patterns of seasonal ocean mass change have typical amplitudes of 1-4 cm, and include maxima in the subtropics and minima in the subpolar regions in hemispheric winters. The subtropical mass gains and subpolar mass losses in the winter spin up both subtropical and subpolar gyres, hence the western boundary current extensions. Seasonal variations in these currents are order 10 Sv, but since the associated depth-averaged current variations are only order 0.1 cm s-1, they would be difficult to detect using in situ oceanographic instruments. a) Amplitude (colors, in cm) and b) phase (colors, in months of the year) of an annual harmonic fit to monthly GRACE Release 05 CSR 500 km smoothed maps (concurrently with a trend and the semiannual harmonic). The 97.5% confidence interval for difference from zero is also indicated (solid black line). Data within 300 km of coastlines are not considered.

Groundwater Depletion in the Middle East from GRACE with Implications for Transboundary Water Management in the Tigris-Euphrates-Western Iran Region

Science.gov (United States)

Voss, Katalyn A.; Famiglietti, James S.; Lo, MinHui; De Linage, Caroline; Rodell, Matthew; Swenson, Sean C.

2013-01-01

In this study, we use observations from the Gravity Recovery and Climate Experiment (GRACE) satellite mission to evaluate freshwater storage trends in the north-central Middle East, including portions of the Tigris and Euphrates River Basins and western Iran, from January 2003 to December 2009. GRACE data show an alarming rate of decrease in total water storage of approximately -27.2 plus or minus 0.6 millimeters per year equivalent water height, equal to a volume of 143.6 cubic kimometers during the course of the study period. Additional remote-sensing information and output from land surface models were used to identify that groundwater losses are the major source of this trend. The approach used in this study provides an example of ''best current capabilities'' in regions like the Middle East, where data access can be severely limited. Results indicate that the region lost 17.3 plus or minus 2.1 millimeters per year equivalent water height of groundwater during the study period, or 91.3 plus or minus 10.9 cubic kilometers in volume. Furthermore, results raise important issues regarding water use in transboundary river basins and aquifers, including the necessity of international water use treaties and resolving discrepancies in international water law, while amplifying the need for increased monitoring for core components of the water budget.

Drought Assessment over the Four Major River Basins of India using GRACE-based estimates of Water Availability

Science.gov (United States)

Sinha, D.; Syed, T. H.

2017-12-01

Drought is a natural disaster that has mutilating consequences over agriculture, ecosystems, economy and the society. Over the past few decades, drought related catastrophe, associated with global climate change, has escalated all across the world. Identification and analysis of drought utilizing individual hydrologic variables may be inadequate owing to the multitude of factors that are associated with the phenomenon. Therefore it is crucial to develop techniques that warrant comprehensive monitoring and assessment of droughts. In this study we propose a novel drought index (Water Availability Index (WAI)) that comprehends all the aspects of meteorologic, agricultural and hydrologic droughts. The proposed framework underscores the conceptualization and utilization of water availability, quantified as an integrated estimate of land water storage, using Gravity Recovery and Climate Experiment (GRACE) observations, and precipitation. The methodology is employed over four major river basins of India (i.e. Ganga, Krishna, Godavari and Mahanadi) for a period of 155 months (April 2002 to February 2015). Results exhibit the potential of the propounded index (WAI) to recognize drought events and impart insightful quantification of drought severity. WAI also demonstrates enhanced outcomes in comparison to other commonly used drought indices like PDSI, SPI, SPEI and SRI. In general there are at least three major drought periods with intensities ranging from moderate to severe in almost all river basins. The longest drought period, extending for 27 months, from September 2008 to November 2010, is observed in the Mahanadi basin. Results from this study confirm the potential of this technique as an effective tool for the characterization of drought at large spatial scales, which will only excel with better quantification and extended availability of terrestrial water storage observations from the GRACE-Follow On mission.

Results of the indoor radiological survey at the W.R. Grace Co., Curtis Bay site, Baltimore, Maryland

International Nuclear Information System (INIS)

Cottrell, W.D.; Foley, R.D.; Johnson, C.A.

1989-07-01

The W.R. Grace Company, Davison Chemical Division, conducted developmental research and extraction of thorium from monazite ore at its Curtis Bay facility in Baltimore, Maryland, during the 1950s under contract to the Atomic Energy Commission (AEC). Only one of the numerous buildings on the site was used for these operations. A 1979 aerial survey of the site for the Department of Energy (DOE) indicated that a comprehensive ground survey was required to determine whether or not any contamination remained from the AEC activities in that building. A radiological scoping survey performed later that year for DOE by a team from the Measurement Applications and Development Group of the Health and Safety Research Division, Oak Ridge National Laboratory (ORNL), disclosed surface contamination (alpha) levels in excess of DOE criteria on all five levels of the building. As a result of this finding, two additional surveys were performed in 1986 by ORNL at the request of DOE to evaluate any present or potential health risk. They are detailed in this report. The results of the 1986 surveys revealed several areas having elevated levels of radiation as a result of significant quantities of thorium on some building surfaces such as floors and ceiling beams. Most areas were small spots and in locations of low occupancy; thus, the possibility for significant exposure to workers was judged to be low. To confirm this evaluation, annual radiation exposure estimates for workers frequenting the few, larger contaminated areas on the site were derived using ORNL survey data and occupancy factors provided by the W.R. Grace Company. Estimates ranged from 27 to 41 mrem/yr or a maximum of 41% of the basic dose limit of 100 mrem/yr for members of the general public. 2 refs., 14 figs., 8 tabs

Groundwater Depletion in the West Liaohe River Basin, China and Its Implications Revealed by GRACE and In Situ Measurements

Directory of Open Access Journals (Sweden)

Yulong Zhong

2018-03-01

Full Text Available The West Liaohe River Basin (WLRB is one of the most sensitive areas to climate change in China and an important grain production base in the Inner Mongolia Autonomous Region of China. Groundwater depletion in this region is becoming a critical issue. Here, we used the Gravity Recovery and Climate Experiment (GRACE satellite data and in situ well observations to estimate groundwater storage (GWS variations and discussed the driving factors of GWS changes in the WLRB. GRACE detects a GWS decline rate of −0.92 ± 0.49 km3/yr in the WLRB during 2005–2011, consistent with the estimate from in situ observations (−0.96 ± 0.19 km3/yr. This long-term GWS depletion is attributed to reduced precipitation and extensive groundwater overexploitation in the 2000s. Long-term groundwater level observations and reconstructed total water storage variations since 1980 show favorable agreement with precipitation anomalies at interannual timescales, both of which are significantly influenced by the El Niño-Southern Oscillation (ENSO. Generally, the WLRB receives more/less precipitation during the El Niño/La Niña periods. One of the strongest El Niño events on record in 1997–1998 and a subsequent strong La Niña drastically transform the climate of WLRB into a decade-long drought period, and accelerate the groundwater depletion in the WLRB after 1998. This study demonstrates the significance of integrating satellite observations, ground-based measurements, and climatological data for interpreting regional GWS changes from a long-term perspective.

Terrestrial water storage changes over Xinjiang extracted by combining Gaussian filter and multichannel singular spectrum analysis from GRACE

Science.gov (United States)

Guo, Jinyun; Li, Wudong; Chang, Xiaotao; Zhu, Guangbin; Liu, Xin; Guo, Bin

2018-04-01

Water resource management is crucial for the economic and social development of Xinjiang, an arid area located in the Northwest China. In this paper, the time variations of gravity recovery and climate experiment (GRACE)-derived monthly gravity field models from 2003 January to 2013 December are analysed to study the terrestrial water storage (TWS) changes in Xinjiang using the multichannel singular spectrum analysis (MSSA) with a Gaussian smoothing radius of 400 km. As an extended singular spectrum analysis (SSA), MSSA is more flexible to deal with multivariate time-series in terms of estimating periodic components and trend, reducing noise and identifying patterns of similar spatiotemporal behaviour thanks to the data-adaptive nature of the base functions. Combining MSSA and Gaussian filter can not only obviously remove the north-south striping errors in the GRACE solutions but also reduce the leakage errors, which can increase the signal-to-noise ratio by comparing with the traditional procedure, that is, empirical decorrelation method followed with the Gaussian filtering. The spatiotemporal characteristics of TWS changes in Xinjiang were validated against the Global Land Dynamics Assimilation System, the Climate Prediction Center and in-situ precipitation data. The water storage in Xinjiang shows the relatively large fluctuation from 2003 January to 2013 December, with a drop from 2006 January to 2008 December due to the drought event and an obvious rise from 2009 January to 2010 December because of the high precipitation. Spatially, the TWS has been increasing in the south Xinjiang, but decreasing in the north Xinjiang. The minimum rate of water storage change is -4.4 mm yr-1 occurring in the central Tianshan Mountain.

Exactitud pronóstica de las escalas GRACE y TIMI en pacientes llevados a intervencionismo percutáneo por síndrome coronario agudo sin elevación del ST

Directory of Open Access Journals (Sweden)

Luz A. Ocampo, MD

2013-05-01

Conclusion: The overall accuracy of the TIMI and GRACE scores in the patients studied is not adequate, a fact which can be explained because it is a cohort of patients undergoing early intervention and with contemporary drug therapy for acute coronary syndrome.

What can we learn from the self-attraction and loading fingerprints about pre-GRACE mass-loss acceleration from Greenland and Antarctica?

Science.gov (United States)

Davis, J. L.; Vinogradova, N. T.

2017-12-01

Tide-gauge records from the North Atlantic reveal significant acceleration in sea level starting in the late 20th century. We have analyzed the tide-gauge data using a model in which the accelerations are assumed to be zero prior to 1990. The estimated accelerations range from -1 to +3 m cy-2 and exhibit a systematic spatial variability. Davis and Vinogradova [2017] demonstrated that to model this variability in sea-level acceleration requires contributions from several distinct physical processes: accelerated mass loss from the Greenland and Antarctic Ice Sheets and acceleration associated with ocean circulation and heat uptake. Atmospheric pressure also contributes to the observed changes in sea level, at a much smaller amplitude. Because we are focusing on sea-level accelerations (i.e., sea-level rate changes), the contribution from Glacial Isostatic Adjustment (GIA) is negligible. Modeling of observed sea-level acceleration is achieved using external constraints for the important physical processes. Using GRACE results, we can calculate the sea-level "fingerprints" for Greenland and Antarctica associated with mass loading and gravitational perturbations. For the North Atlantic, Greenland induces a significant spatial variation in sea-level change—dominated by the solid-Earth response to the mass loss—whereas Antarctica contributes a spatially constant acceleration. The observations prefer a scaling of the solid-Earth/gravitational response, and we present the implications of this result for ice-mass changes prior to the onset of GRACE observations (2002-3).

Status of Electrostatic Accelerometer Development for Gravity Recovery and Climate Experiment Follow-On Mission (GRACE FO)

Science.gov (United States)

Perrot, Eddy; Boulanger, Damien; Christophe, Bruno; Foulon, Bernard; Liorzou, Françoise; Lebat, Vincent; Huynh, Phuong-Anh

2015-04-01

The GRACE FO mission, led by the JPL (Jet Propulsion Laboratory), is an Earth-orbiting gravity mission, continuation of the GRACE mission, which will produce an accurate model of the Earth's gravity field variation providing global climatic data during five years at least. The mission involves two satellites in a loosely controlled tandem formation, with a micro-wave link measuring the inter-satellites distance variation. Earth's mass distribution non-uniformities cause variations of the inter-satellite distance. This variation is measured to recover gravity, after subtracting the non-gravitational contributors, as the residual drag. ONERA (the French Aerospace Lab) is developing, manufacturing and testing electrostatic accelerometers measuring this residual drag applied on the satellites. The accelerometer is composed of two main parts: the Sensor Unit (including the Sensor Unit Mechanics - SUM - and the Front-End Electronic Unit - FEEU) and the Interface Control Unit - ICU. In the Accelerometer Core, located in the Sensor Unit Mechanics, the proof mass is levitated and maintained at the center of an electrode cage by electrostatic forces. Thus, any drag acceleration applied on the satellite involves a variation on the servo-controlled electrostatic suspension of the mass. The voltage on the electrodes providing this electrostatic force is the measurement output of the accelerometer. The impact of the accelerometer defaults (geometry, electronic and parasitic forces) leads to bias, misalignment and scale factor error, non-linearity and noise. Some of these accelerometer defaults are characterized by tests with micro-gravity pendulum bench on ground and with drops in ZARM catapult. The Critical Design Review was achieved successfully on September 2014. The Engineering Model (EM) was integrated and tested successfully, with ground levitation, drops, Electromagnetic Compatibility and thermal vacuum. The integration of the first Flight Model has begun on December 2014

Application of the Convolution Formalism to the Ocean Tide Potential: Results from the Gravity and Recovery and Climate Experiment (GRACE)

Science.gov (United States)

Desai, S. D.; Yuan, D. -N.

2006-01-01

A computationally efficient approach to reducing omission errors in ocean tide potential models is derived and evaluated using data from the Gravity Recovery and Climate Experiment (GRACE) mission. Ocean tide height models are usually explicitly available at a few frequencies, and a smooth unit response is assumed to infer the response across the tidal spectrum. The convolution formalism of Munk and Cartwright (1966) models this response function with a Fourier series. This allows the total ocean tide height, and therefore the total ocean tide potential, to be modeled as a weighted sum of past, present, and future values of the tide-generating potential. Previous applications of the convolution formalism have usually been limited to tide height models, but we extend it to ocean tide potential models. We use luni-solar ephemerides to derive the required tide-generating potential so that the complete spectrum of the ocean tide potential is efficiently represented. In contrast, the traditionally adopted harmonic model of the ocean tide potential requires the explicit sum of the contributions from individual tidal frequencies. It is therefore subject to omission errors from neglected frequencies and is computationally more intensive. Intersatellite range rate data from the GRACE mission are used to compare convolution and harmonic models of the ocean tide potential. The monthly range rate residual variance is smaller by 4-5%, and the daily residual variance is smaller by as much as 15% when using the convolution model than when using a harmonic model that is defined by twice the number of parameters.

Equivalent water height extracted from GRACE gravity field model with robust independent component analysis

Science.gov (United States)

Guo, Jinyun; Mu, Dapeng; Liu, Xin; Yan, Haoming; Dai, Honglei

2014-08-01

The Level-2 monthly GRACE gravity field models issued by Center for Space Research (CSR), GeoForschungs Zentrum (GFZ), and Jet Propulsion Laboratory (JPL) are treated as observations used to extract the equivalent water height (EWH) with the robust independent component analysis (RICA). The smoothing radii of 300, 400, and 500 km are tested, respectively, in the Gaussian smoothing kernel function to reduce the observation Gaussianity. Three independent components are obtained by RICA in the spatial domain; the first component matches the geophysical signal, and the other two match the north-south strip and the other noises. The first mode is used to estimate EWHs of CSR, JPL, and GFZ, and compared with the classical empirical decorrelation method (EDM). The EWH STDs for 12 months in 2010 extracted by RICA and EDM show the obvious fluctuation. The results indicate that the sharp EWH changes in some areas have an important global effect, like in Amazon, Mekong, and Zambezi basins.

Mass balance of Graham Land at present-day and over the past 150 years using GRACE and GNSS station data

Science.gov (United States)

Ivins, E. R.; Wiese, D. N.; Watkins, M. M.; Landerer, F. W.; Simms, A.; Yuan, D. N.; Boening, C.; Domack, E. W.

2014-12-01

The Antarctic Peninsula has been warming at an anomalously high rate with respect to other parts of the globe for the past 115 years. The increased atmospheric and ocean warmth has caused both increased precipitation and loss of buttressing near the trunks of the numerous outlet glaciers that drain into the ocean. The measurements by space gravimetry (Gravity Recovery and Climate Experiment or 'GRACE') have been crucial to identifying the dominant role of losses in butressing in a decadal-scale total ice mass budget for the Peninsula north of about 69 °S. One of the major losses of butressing came at a time when the Larsen B Ice Shelf catastrophically disintegrated into the northernmost Weddell Sea in March of 2002, the same month that GRACE was launched into orbit. The solid Earth rebounded in phase with the speed-up of the unbutressed outlet glaciers as evidenced by GNSS station data. The process has been repeating itself throughout the northern Peninsula since the late 1980's. Larsen A Ice Shelf breakup (LAISb) occurred, for example, in the Austral summer of 1993. Rott et al. (2011) have estimated a velocity acceleration at the trunks of 11 LBISb outlet glaciers for which flux-gate mass transport can be measured. Butress loss caused an increase in discharge of 4.3 ± 1.6 Gt/a in 2008, relative to measurements that span 1995-1999 for 11 Larsen B feeding glaciers. GRACE analysis centers have now released 12 years of monthly solutions (RL05) for global mass change. Solutions for the region of the Peninsula north of 69 ° S (Graham Land) using both constrained and unconstrained mascon methods show 2003-2011 net ice loss to the oceans with a trend of greater than 32 Gt/yr (Ivins et al., 2011; Luthcke et al., 2013). A new set of mascon solutions developed by JPL (Wiese et al., 2014) provide a high-resolution look at the evolution of mass in the Antarctic Peninsula from 2003-2014. We employ a time-series from these solutions and discuss the evolution of mass changes

Exploiting the Modified Colombo-Nyquist Rule for Co-estimating Sub-monthly Gravity Field Solutions from a GRACE-like Mission

Science.gov (United States)

Devaraju, B.; Weigelt, M.; Mueller, J.

2017-12-01

In order to suppress the impact of aliasing errors on the standard monthly GRACE gravity-field solutions, co-estimating sub-monthly (daily/two-day) low-degree solutions has been suggested as a solution. The maximum degree of the low-degree solutions is chosen via the Colombo-Nyquist rule of thumb. However, it is now established that the sampling of satellites puts a restriction on the maximum estimable order and not the degree - modified Colombo-Nyquist rule. Therefore, in this contribution, we co-estimate low-order sub-monthly solutions, and compare and contrast them with the low-degree sub-monthly solutions. We also investigate their efficacies in dealing with aliasing errors.

Vastukarva pai / Mari Laaniste

Index Scriptorium Estoniae

Laaniste, Mari, 1977-

2007-01-01

Mängufilm "Karusnahk: Diane Arbuse kujutletav portree" ("Fur: An Imaginary Portrait of Diane Arbuse") : stsenarist Erin Cressida Wilson : režissöör Steven Shainberg : nimiosas Nicole Kidman : Ameerika Ühendriigid 2006

Arctic sea level change over the past 2 decades from GRACE gradiometry and multi-mission satellite altimetry

DEFF Research Database (Denmark)

Andersen, O. B.; Stenseng, L.; Sørensen, C. S.

2014-01-01

The Arctic is still an extremely challenging region for theuse of remote sensing for sea level studies. Despite the availability of 20 years of altimetry, only very limited sea level observations exist in the interior of the Arctic Ocean. However, with Cryosat-2 SAR altimetry the situation...... gradiometer observations from the ESA GOCE mission, we are now able to derive a mean dynamic topography of the Arctic Ocean with unprecedented accuracy to constrain the Arctic Ocean circulation controlling sea level variations in the Arctic. We present both a new estimation of the mean ocean circulation...... and new estimates of large scale sea level changes based on satellite data and perform an estimation of the fresh waterstorage increase over the last decade using temporal gravity changes from the GRACE satellite....

Combining satellite radar altimetry, SAR surface soil moisture and GRACE total storage changes for hydrological model calibration in a large poorly gauged catchment

Directory of Open Access Journals (Sweden)

C. Milzow

2011-06-01

Full Text Available The availability of data is a major challenge for hydrological modelling in large parts of the world. Remote sensing data can be exploited to improve models of ungauged or poorly gauged catchments. In this study we combine three datasets for calibration of a rainfall-runoff model of the poorly gauged Okavango catchment in Southern Africa: (i surface soil moisture (SSM estimates derived from radar measurements onboard the Envisat satellite; (ii radar altimetry measurements by Envisat providing river stages in the tributaries of the Okavango catchment, down to a minimum river width of about one hundred meters; and (iii temporal changes of the Earth's gravity field recorded by the Gravity Recovery and Climate Experiment (GRACE caused by total water storage changes in the catchment. The SSM data are shown to be helpful in identifying periods with over-respectively underestimation of the precipitation input. The accuracy of the radar altimetry data is validated on gauged subbasins of the catchment and altimetry data of an ungauged subbasin is used for model calibration. The radar altimetry data are important to condition model parameters related to channel morphology such as Manning's roughness. GRACE data are used to validate the model and to condition model parameters related to various storage compartments in the hydrological model (e.g. soil, groundwater, bank storage etc.. As precipitation input the FEWS-Net RFE, TRMM 3B42 and ECMWF ERA-Interim datasets are considered and compared.

Using NASA's GRACE and SMAP satellites to measure human impacts on the water cycle

Science.gov (United States)

Reager, J. T., II; Castle, S.; Turmon, M.; Famiglietti, J. S.; Fournier, S.

2017-12-01

Two satellite missions, the Gravity Recovery and Climate Experiment (GRACE) mission and the Soil Moisture Active Passive (SMAP) mission are enabling the measurement of the dynamic state of the water cycle globally, offering a unique opportunity for the study of human impacts on terrestrial hydrology and an opportunity to quantify the direct augmentation of natural cycles by human activities. While many model-data fusion studies aim to apply observations to improve model performance, we present recent studies on measuring the multi-scale impacts of human activities by differencing or contrasting model simulations and observations. Results that will be presented include studies on: the measurement of human impacts on evapotranspiration in the Colorado River Basin; the estimation of the human portion of groundwater depletion in the Southwestern U.S.; and the influence of irrigation on runoff generation in the Mississippi River basin. Each of these cases has a unique implications for the sustainable use of natural resources by humans, and indicate the relevant extent and magnitude of human influence on natural processes, suggesting their importance for inclusion in hydrology and land-surface models.

EGSIEM combination service: combination of GRACE monthly K-band solutions on normal equation level

Science.gov (United States)

Meyer, Ulrich; Jean, Yoomin; Arnold, Daniel; Jäggi, Adrian

2017-04-01

The European Gravity Service for Improved Emergency Management (EGSIEM) project offers a scientific combination service, combining for the first time monthly GRACE gravity fields of different analysis centers (ACs) on normal equation (NEQ) level and thus taking all correlations between the gravity field coefficients and pre-eliminated orbit and instrument parameters correctly into account. Optimal weights for the individual NEQs are commonly derived by variance component estimation (VCE), as is the case for the products of the International VLBI Service (IVS) or the DTRF2008 reference frame realisation that are also derived by combination on NEQ-level. But variance factors are based on post-fit residuals and strongly depend on observation sampling and noise modeling, which both are very diverse in case of the individual EGSIEM ACs. These variance factors do not necessarily represent the true error levels of the estimated gravity field parameters that are still governed by analysis noise. We present a combination approach where weights are derived on solution level, thereby taking the analysis noise into account.

Explorations Around "Graceful Failure" in Transportation Infrastructure: Lessons Learned By the Infrastructure and Climate Network (ICNet)

Science.gov (United States)

Jacobs, J. M.; Thomas, N.; Mo, W.; Kirshen, P. H.; Douglas, E. M.; Daniel, J.; Bell, E.; Friess, L.; Mallick, R.; Kartez, J.; Hayhoe, K.; Croope, S.

2014-12-01

Recent events have demonstrated that the United States' transportation infrastructure is highly vulnerable to extreme weather events which will likely increase in the future. In light of the 60% shortfall of the $900 billion investment needed over the next five years to maintain this aging infrastructure, hardening of all infrastructures is unlikely. Alternative strategies are needed to ensure that critical aspects of the transportation network are maintained during climate extremes. Preliminary concepts around multi-tier service expectations of bridges and roads with reference to network capacity will be presented. Drawing from recent flooding events across the U.S., specific examples for roads/pavement will be used to illustrate impacts, disruptions, and trade-offs between performance during events and subsequent damage. This talk will also address policy and cultural norms within the civil engineering practice that will likely challenge the application of graceful failure pathways during extreme events.

Using Technology to Facilitate Differentiated High School Science Instruction

Science.gov (United States)

Maeng, Jennifer L.

2017-10-01

This qualitative investigation explored the beliefs and practices of one secondary science teacher, Diane, who differentiated instruction and studied how technology facilitated her differentiation. Diane was selected based on the results of a previous study, in which data indicated that Diane understood how to design and implement proactively planned, flexible, engaging instructional activities in response to students' learning needs better than the other study participants. Data for the present study included 3 h of semi-structured interview responses, 37.5 h of observations of science instruction, and other artifacts such as instructional materials. This variety of data allowed for triangulation of the evidence. Data were analyzed using a constant comparative approach. Results indicated that technology played an integral role in Diane's planning and implementation of differentiated science lessons. The technology-enhanced differentiated lessons employed by Diane typically attended to students' different learning profiles or interest through modification of process or product. This study provides practical strategies for science teachers beginning to differentiate instruction, and recommendations for science teacher educators and school and district administrators. Future research should explore student outcomes, supports for effective formative assessment, and technology-enhanced readiness differentiation among secondary science teachers.

Predictive modeling of cholera using GRACE and TRMM satellite data

Science.gov (United States)

Jutla, A.; Akanda, A. S. S.; Colwell, R. R.

2015-12-01

Cholera outbreaks can be classified in three forms- epidemic (sudden or seasonal outbreaks), endemic (recurrence and persistence of the disease for several consecutive years) and mixed-mode endemic (combination of certain epidemic and endemic conditions) with significant spatial and temporal heterogeneity. Endemic cholera is related to floods and droughts in regions where water and sanitation infrastructure are inadequate or insufficient. With more than a decade of terrestrial water storage (TWS) data obtained from Gravity Recovery and Climate Experiment (GRACE), understanding dynamics of river discharge is now feasible. We explored lead-lag relationships between TWS in the Ganges-Brahmaputra-Meghna (GBM) basin and endemic cholera in Bangladesh. Since bimodal seasonal peaks in cholera in Bangladesh occur during the spring and autumn season, two separate models, between TWS and disease time series (2002 to 2010) were developed. TWS, hence water availability, showed an asymmetrical, strong association with spring (τ=-0.53; pcholera prevalence up to five to six months in advance. One unit (cm of water) decrease in water availability in the basin increased odds of above normal cholera by 24% [confidence interval (CI) 20-31%; pcholera in the autumn by 29% [CI:22-33%; pcholera is related with warm temperatures and heavy rainfall. Using TRMM data for several locations in Asia and Africa, probability of cholera increases 18% [CI:15-23%; p<0.05] after heavy precipitation resulted in a societal conditions where access to safe water and sanitation was disrupted. Results from mechanistic modeling framework using systems approach that include satellite based hydroclimatic information with tradition disease transmission models will also be presented.

Feasibility and benefits of group-based exercise in residential aged care adults: a pilot study for the GrACE programme

Directory of Open Access Journals (Sweden)

Samantha Fien

2016-05-01

Full Text Available The objective of the study was to examine the feasibility and benefits of a group resistance training exercise programme for improving muscle function in institutionalised older adults. A feasibility and acceptability study was designed for a residential aged care (RAC facility, based on the Gold Coast, Australia. Thirty-seven adults, mean age 86.8 ± 6.1 years (30 females living in a RAC facility. Participants were allocated into an exercise (n = 20 or control (n = 17 group. The exercise group, the Group Aged Care Exercise (GrACE programme, performed 12 weeks of twice weekly resistance exercises. Feasibility was measured via recruitment rate, measurement (physiological and surveys completion rate, loss-to-follow-up, exercise session adherence, adverse events, and ratings of burden and acceptability. Muscle function was assessed using gait speed, sit-to-stand and handgrip strength assessments. All intervention participants completed pre- and post-assessments, and the exercise intervention, with 85% (n = 17 of the group attending ≥ 18 of the 24 sessions and 15% (n = 3 attending all sessions. Acceptability was 100% with exercise participants, and staff who had been involved with the programme strongly agreed that the participants “Benefited from the programme.” There were no adverse events reported by any participants during the exercise sessions. When compared to the control group, the exercise group experienced significant improvements in gait speed (F(4.078 = 8.265, p = 0.007, sit to stand performance (F(3.24 = 11.033, p = 0.002 and handgrip strength (F(3.697 = 26.359, p < 0.001. Resistance training via the GrACE programme is feasible, safe and significantly improves gait speed, sit-to-stand performance and handgrip strength in RAC adults.

The platelet activating factor acetyl hydrolase, oxidized low-density lipoprotein, paraoxonase 1 and arylesterase levels in treated and untreated patients with polycystic ovary syndrome.

Science.gov (United States)

Carlioglu, Ayse; Kaygusuz, Ikbal; Karakurt, Feridun; Gumus, Ilknur Inegol; Uysal, Aysel; Kasapoglu, Benan; Armutcu, Ferah; Uysal, Sema; Keskin, Esra Aktepe; Koca, Cemile

2014-11-01

To evaluate the platelet activating factor acetyl hydrolyze (PAF-AH), oxidized low-density lipoprotein (ox-LDL), paraoxonase 1 (PON1), arylesterase (ARE) levels and the effects of metformin and Diane-35 (ethinyl oestradiol + cyproterone acetate) therapies on these parameters and to determine the PON1 polymorphisms among PCOS patients. Ninety patients with PCOS, age 30, and body mass index-matched healthy controls were included in the study. Patients were divided into three groups: metformin treatment, Diane-35 treatment and no medication groups. The treatment with metformin or Diane-35 was continued for 6 months and all subjects were evaluated with clinical and biochemical parameters 6 months later. One-way Anova test, t test and non-parametric Mann-Whitney U tests were used for statistical analysis. PAF-AH and ox-LDL levels were statistically significantly higher in untreated PCOS patients than controls, and they were statistically significantly lower in patients treated with metformin or Diane-35 than untreated PCOS patients. In contrast, there were lower PON1 (not statistically significant) and ARE (statistically significant) levels in untreated PCOS patients than the control group and they significantly increased after metformin and Diane-35 treatments. In PCOS patients serum PON1 levels for QQ, QR and RR phenotypes were statistically significantly lower than the control group. In patients with PCOS, proatherogenic markers increase. The treatment of PCOS with metformin or Diane-35 had positive effects on lipid profile, increased PON1 level, which is a protector from atherosclerosis and decreased the proatherogenic PAF-AH and ox-LDL levels.

“Psychosocial Interventions for Cancer Survivors, Caregivers and Family Members—One Size Does Not Fit All: My Perspective as a Young Adult Survivor, Advocate and Oncology Social Worker” a personal reflection by Mary Grace Bontempo - Office of Cancer Survivorship

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“Psychosocial Interventions for Cancer Survivors, Caregivers and Family Members—One Size Does Not Fit All: My Perspective as a Young Adult Survivor, Advocate and Oncology Social Worker” a personal reflection by Mary Grace Bontempo page

High Artic Glaciers and Ice Caps Ice Mass Change from GRACE, Regional Climate Model Output and Altimetry.

Science.gov (United States)

Ciraci, E.; Velicogna, I.; Fettweis, X.; van den Broeke, M. R.

2016-12-01

The Arctic hosts more than the 75% of the ice covered regions outside from Greenland and Antarctica. Available observations show that increased atmospheric temperatures during the last century have contributed to a substantial glaciers retreat in all these regions. We use satellite gravimetry by the NASA's Gravity Recovery and Climate Experiment (GRACE), and apply a least square fit mascon approach to calculate time series of ice mass change for the period 2002-2016. Our estimates show that arctic glaciers have constantly contributed to the sea level rise during the entire observation period with a mass change of -170+/-20 Gt/yr equivalent to the 80% of the total ice mass change from the world Glacier and Ice Caps (GIC) excluding the Ice sheet peripheral GIC, which we calculated to be -215+/-32 GT/yr, with an acceleration of 9+/-4 Gt/yr2. The Canadian Archipelago is the main contributor to the total mass depletion with an ice mass trend of -73+/-9 Gt/yr and a significant acceleration of -7+/-3 Gt/yr2. The increasing mass loss is mainly determined by melting glaciers located in the northern part of the archipelago.In order to investigate the physical processes driving the observed ice mass loss we employ satellite altimetry and surface mass balance (SMB) estimates from Regional climate model outputs available for the same time period covered by the gravimetry data. We use elevation data from the NASA ICESat (2003-2009) and ESA CryoSat-2 (2010-2016) missions to estimate ice elevation changes. We compare GRACE ice mass estimates with time series of surface mass balance from the Regional Climate Model (RACMO-2) and the Modèle Atmosphérique Régional (MAR) and determine the portion of the total mass change explained by the SMB signal. We find that in Iceland and in the and the Canadian Archipelago the SMB signal explains most of the observed mass changes, suggesting that ice discharge may play a secondary role here. In other region, e.g. in Svalbar, the SMB signal

Monitoring Groundwater Storage Changes in the Loess Plateau Using GRACE Satellite Gravity Data, Hydrological Models and Coal Mining Data

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Xiaowei Xie

2018-04-01

Full Text Available Monitoring the groundwater storage (GWS changes is crucial to the rational utilization of groundwater and to ecological restoration in the Loess Plateau of China, which is one of the regions with the most extreme ecological environmental damage in the world. In this region, the mass loss caused by coal mining can reach the level of billions of tons per year. For this reason, in this work, in addition to Gravity Recovery and Climate Experiment (GRACE satellite gravity data and hydrological models, coal mining data were also used to monitor GWS variation in the Loess Plateau during the period of 2005–2014. The GWS changes results from different GRACE solutions, that is, the spherical harmonics (SH solutions, mascon solutions, and Slepian solutions (which are the Slepian localization of SH solutions, were compared with in situ GWS changes, obtained from 136 groundwater observation wells, and the aim was to acquire the most robust GWS changes. The results showed that the GWS changes from mascon solutions (mascon-GWS match best with in situ GWS changes, showing the highest correlation coefficient, lowest root mean square error (RMSE values and nearest annual trend. Therefore, the Mascon-GWS changes are used for the spatial-temporal analysis of GWS changes. Based on which, the groundwater depletion rate of the Loess Plateau was −0.65 ± 0.07 cm/year from 2005–2014, with a more severe consumption rate occurring in its eastern region, reaching about −1.5 cm/year, which is several times greater than those of the other regions. Furthermore, the precipitation and coal mining data were used for analyzing the causes of the groundwater depletion: the results showed that seasonal changes in groundwater storage are closely related to rainfall, but the groundwater consumption is mainly due to human activities; coal mining in particular plays a major role in the serious groundwater consumption in eastern region of the study area. Our results will help in

Tests Results of the Electrostatic Accelerometer Flight Models for Gravity Recovery and Climate Experiment Follow-On Mission (GRACE FO)

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Perrot, E.; Boulanger, D.; Christophe, B.; Foulon, B.; Lebat, V.; Huynh, P. A.; Liorzou, F.

2015-12-01

The GRACE FO mission, led by the JPL (Jet Propulsion Laboratory), is an Earth-orbiting gravity mission, continuation of the GRACE mission, which will produce an accurate model of the Earth's gravity field variation providing global climatic data during five years at least. The mission involves two satellites in a loosely controlled tandem formation, with a micro-wave link measuring the inter-satellites distance variation. Earth's mass distribution non-uniformities cause variations of the inter-satellite distance. This variation is measured to recover gravity, after subtracting the non-gravitational contributors, as the residual drag. ONERA (the French Aerospace Lab) is developing, manufacturing and testing electrostatic accelerometers measuring this residual drag applied on the satellites. The accelerometer is composed of two main parts: the Sensor Unit (including the Sensor Unit Mechanics - SUM - and the Front-End Electronic Unit - FEEU) and the Interface Control Unit - ICU. In the Accelerometer Core, located in the Sensor Unit Mechanics, the proof mass is levitated and maintained at the center of an electrode cage by electrostatic forces. Thus, any drag acceleration applied on the satellite involves a variation on the servo-controlled electrostatic suspension of the mass. The voltage on the electrodes providing this electrostatic force is the output measurement of the accelerometer. The impact of the accelerometer defaults (geometry, electronic and parasitic forces) leads to bias, misalignment and scale factor error, non-linearity and noise. Some of these accelerometer defaults are characterized by tests with micro-gravity pendulum bench on ground and with drops in ZARM catapult. The Critical Design Review was achieved successfully on September 2014. The Engineering Model (EM) was integrated and tested successfully, with ground levitation, drops, Electromagnetic Compatibility and thermal vacuum. The integration of the two Flight Models was done on July 2015. The

Establishing a Global Radiation Oncology Collaboration in Education (GRaCE): Objectives and priorities.

Science.gov (United States)

Turner, Sandra; Eriksen, Jesper G; Trotter, Theresa; Verfaillie, Christine; Benstead, Kim; Giuliani, Meredith; Poortmans, Philip; Holt, Tanya; Brennan, Sean; Pötter, Richard

2015-10-01

Representatives from countries and regions world-wide who have implemented modern competency-based radiation- or clinical oncology curricula for training medical specialists, met to determine the feasibility and value of an ongoing international collaboration. In this forum, educational leaders from the ESTRO School, encompassing many European countries adopting the ESTRO Core Curriculum, and clinician educators from Canada, Denmark, the United Kingdom, Australia and New Zealand considered the training and educational arrangements within their jurisdictions, identifying similarities and challenges between programs. Common areas of educational interest and need were defined, which included development of new competency statements and assessment tools, and the application of the latter. The group concluded that such an international cooperation, which might expand to include others with similar goals, would provide a valuable vehicle to ensure training program currency, through sharing of resources and expertise, and enhance high quality radiation oncology education. Potential projects for the Global Radiation Oncology Collaboration in Education (GRaCE) were agreed upon, as was a strategy designed to maintain momentum. This paper describes the rationale for establishing this collaboration, presents a comparative view of training in the jurisdictions represented, and reports early goals and priorities. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Research@ARL: Autonomous Systems. Volume 2, Issue 2

Science.gov (United States)

2013-07-01

communication delays (latency) limit operational tempo . More limiting, tele-operation requires at least one dedicated pair of eyes and hands. In...fabrication process (see schematic in Fig. 3) for PiezoMEMS devices at ARL uses the following process flow with minor variations (i.e., release...57 [12] 3229–38 (2009). 47M. Glickman, P. Tseng, P. Harison, J. Niblock, T. Goldberg , I. B. Judy, and J. W. Judy, “High Performance Lateral Actuating

Evaluation of the NICE mini-GRACE risk scores for acute myocardial infarction using the Myocardial Ischaemia National Audit Project (MINAP) 2003-2009: National Institute for Cardiovascular Outcomes Research (NICOR).

Science.gov (United States)

Simms, Alexander D; Reynolds, Stephanie; Pieper, Karen; Baxter, Paul D; Cattle, Brian A; Batin, Phillip D; Wilson, John I; Deanfield, John E; West, Robert M; Fox, Keith A A; Hall, Alistair S; Gale, Christopher P

2013-01-01

To evaluate the performance of the National Institute for Health and Clinical Excellence (NICE) mini-Global Registry of Acute Coronary Events (GRACE) (MG) and adjusted mini-GRACE (AMG) risk scores. Retrospective observational study. 215 acute hospitals in England and Wales. 137 084 patients discharged from hospital with a diagnosis of acute myocardial infarction (AMI) between 2003 and 2009, as recorded in the Myocardial Ischaemia National Audit Project (MINAP). Model performance indices of calibration accuracy, discriminative and explanatory performance, including net reclassification index (NRI) and integrated discrimination improvement. Of 495 263 index patients hospitalised with AMI, there were 53 196 ST elevation myocardial infarction and 83 888 non-ST elevation myocardial infarction (NSTEMI) (27.7%) cases with complete data for all AMG variables. For AMI, AMG calibration was better than MG calibration (Hosmer-Lemeshow goodness of fit test: p=0.33 vs pModel performance was reduced in patients with NSTEMI, chronic heart failure, chronic renal failure and in patients aged ≥85 years. The AMG and MG risk scores, utilised by NICE, demonstrated good performance across a range of indices using MINAP data, but performed less well in higher risk subgroups. Although indices were better for AMG, its application may be constrained by missing predictors.

A simple groundwater scheme in the TRIP river routing model: global off-line evaluation against GRACE terrestrial water storage estimates and observed river discharges

Directory of Open Access Journals (Sweden)

J.-P. Vergnes

2012-10-01

Full Text Available Groundwater is a non-negligible component of the global hydrological cycle, and its interaction with overlying unsaturated zones can influence water and energy fluxes between the land surface and the atmosphere. Despite its importance, groundwater is not yet represented in most climate models. In this paper, the simple groundwater scheme implemented in the Total Runoff Integrating Pathways (TRIP river routing model is applied in off-line mode at global scale using a 0.5° model resolution. The simulated river discharges are evaluated against a large dataset of about 3500 gauging stations compiled from the Global Data Runoff Center (GRDC and other sources, while the terrestrial water storage (TWS variations derived from the Gravity Recovery and Climate Experiment (GRACE satellite mission help to evaluate the simulated TWS. The forcing fields (surface runoff and deep drainage come from an independent simulation of the Interactions between Soil-Biosphere-Atmosphere (ISBA land surface model covering the period from 1950 to 2008. Results show that groundwater improves the efficiency scores for about 70% of the gauging stations and deteriorates them for 15%. The simulated TWS are also in better agreement with the GRACE estimates. These results are mainly explained by the lag introduced by the low-frequency variations of groundwater, which tend to shift and smooth the simulated river discharges and TWS. A sensitivity study on the global precipitation forcing used in ISBA to produce the forcing fields is also proposed. It shows that the groundwater scheme is not influenced by the uncertainties in precipitation data.

HYDROGRAV - Hydrological model calibration and terrestrial water storage monitoring from GRACE gravimetry and satellite altimetry, First results

DEFF Research Database (Denmark)

Andersen, O.B.; Krogh, P.E.; Michailovsky, C.

2008-01-01

Space-borne and ground-based time-lapse gravity observations provide new data for water balance monitoring and hydrological model calibration in the future. The HYDROGRAV project (www.hydrograv.dk) will explore the utility of time-lapse gravity surveys for hydrological model calibration and terre...... change from 2002 to 2008 along with in-situ gravity time-lapse observations and radar altimetry monitoring of surface water for the southern Africa river basins will be presented.......Space-borne and ground-based time-lapse gravity observations provide new data for water balance monitoring and hydrological model calibration in the future. The HYDROGRAV project (www.hydrograv.dk) will explore the utility of time-lapse gravity surveys for hydrological model calibration...... and terrestrial water storage monitoring. Merging remote sensing data from GRACE with other remote sensing data like satellite altimetry and also ground based observations are important to hydrological model calibration and water balance monitoring of large regions and can serve as either supplement or as vital...

Event planning the ultimate guide to successful meetings, corporate events, fundraising galas, conferences, conventions, incentives and other special events

CERN Document Server

Allen, Judy

2009-01-01

This bestselling all–in–one guide to the event planning business is back and better than ever, fully updated and revised to reflect the very latest trends and best practices in the industry. This handy, comprehensive guide includes forms, checklists, and tips for managing events, as well as examples and case studies of both successful and unsuccessful events. Judy Allen (Toronto, ON, Canada) is founder and President of Judy Allen Productions, a full–service event planning production company.

High Resolution Modeling of the Water Cycle to Refine GRACE Signal Analysis in the Gulf of Alaska Drainage

Science.gov (United States)

Beamer, J.; Hill, D. F.; Arendt, A. A.; Luthcke, S. B.; Liston, G. E.

2015-12-01

A comprehensive study of the Gulf of Alaska (GOA) drainage basin was carried out to improve understanding of the coastal freshwater discharge (FWD) and surface mass balance (SMB) of glaciers. Coastal FWD and SMB for all glacier surfaces were modeled using a suite of physically based, spatially distributed weather, energy-balance snow/ice melt, soil water balance, and runoff routing models at a high resolution (1 km horizontal grid; daily time step). A 35 year hind cast was performed, providing complete records of precipitation, runoff, snow water equivalent (SWE) depth, evapotranspiration, coastal FWD and glacier SMB. Meteorological forcing was provided by the North American Regional Reanalysis (NARR), Modern Era Retrospective Analysis for Research and Applications (MERRA), and NCEP Climate Forecast System Reanalysis (CFSR) datasets. A fourth dataset was created by bias-correcting the NARR data to recently-developed monthly weather grids based on PRISM climatologies (NARR-BC). Each weather dataset and model combination was individually calibrated using PRISM climatologies, streamflow, and glacier mass balance measurements from four locations in the study domain. Simulated mean annual FWD into the GOA ranged from 600 km3 yr-1 using NARR to 850 km3 yr-1 from NARR-BC. The CFSR-forced simulations with optimized model parameters produced a simulated regional water storage that compared favorably to data from the NASA/DLR Gravity Recovery and Climate Experiment (GRACE) high resolution mascon solutions (Figure). Glacier runoff, taken as the sum of rainfall, snow and ice melt occurring on glacier surfaces, ranged from 260 km3 yr-1 from MERRA to 400 km3 yr-1 from NARR-BC, approximately one half of the signal from both glaciers and surrounding terrain. The large contribution from non-glacier surfaces to the seasonal water balance is likely not being fully removed from GRACE solutions aimed at isolating the glacier signal alone. We will discuss methods to use our simulations

Advocacy meets the scientific method.

Science.gov (United States)

Bradford, J; Hilber, J A

2001-01-01

ABSTRACT Dr. Judith Bradford is a social science researcher who has been a key figure in the evolution of lesbian health research. With Caitlin Ryan, Judy was instrumental in creating the National Lesbian Health Care Survey (NLHCS) in the mid-1980s. After assuming the Directorship of the Survey and Evaluation Research Lab (SERL) at the Virginia Commonwealth University (VCU), she became involved in the recent Institute of Medicine (IOM) Committee process, which resulted in increased attention to lesbian health at the national level. The IOM Committee recommendations have been instrumental in lobbying efforts by Judy and others for inclusion of LBGT issues in Healthy People 2010, the United States Public Health Service blueprint used by PHS agencies nationwide. Judy's current activities include helping to develop the Lesbian Health Research Institute and serving as the part-time Director of Lesbian Health Research at Fenway Community Health in Boston.

Geoid-to-Quasigeoid Separation Computed Using the GRACE/GOCE Global Geopotential Model GOCO02S - A Case Study of Himalayas and Tibet

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Mohammad Bagherbandi Robert Tenzer

2013-01-01

Full Text Available The geoid-to-quasigeoid correction has been traditionally computed approximately as a function of the planar Bouguer gravity anomaly and the topographic height. Recent numerical studies based on newly developed theoretical models, however, indicate that the computation of this correction using the approximate formula yields large errors especially in mountainous regions with computation points at high elevations. In this study we investigate these approximation errors at the study area which comprises Himalayas and Tibet where this correction reaches global maxima. Since the GPS-leveling and terrestrial gravity datasets in this part of the world are not (freely available, global gravitational models (GGMs are used to compute this correction utilizing the expressions for a spherical harmonic analysis of the gravity field. The computation of this correction can be done using the GGM coefficients taken from the Earth Gravitational Model 2008 (EGM08 complete to degree 2160 of spherical harmonics. The recent studies based on a regional accuracy assessment of GGMs have shown that the combined GRACE/GOCE solutions provide a substantial improvement of the Earth¡¦s gravity field at medium wavelengths of spherical harmonics compared to EGM08. We address this aspect in numerical analysis by comparing the gravity field quantities computed using the satellite-only combined GRACE/GOCE model GOCO02S against the EGM08 results. The numerical results reveal that errors in the geoid-to-quasigeoid correction computed using the approximate formula can reach as much as ~1.5 m. We also demonstrate that the expected improvement of the GOCO02S gravity field quantities at medium wavelengths (within the frequency band approximately between 100 and 250 compared to EGM08 is as much as ±60 mGal and ±0.2 m in terms of gravity anomalies and geoid/quasigeoid heights respectively.

Improved regional sea-level estimates from Ice Sheets, Glaciers and land water storage using GRACE time series and other data

Science.gov (United States)

He, Z.; Velicogna, I.; Hsu, C. W.; Rignot, E. J.; Mouginot, J.; Scheuchl, B.; Fettweis, X.; van den Broeke, M. R.

2017-12-01

Changes in ice sheets, glaciers and ice caps (GIC) and land water mass cause regional sea level variations that differ significantly from a uniform re-distribution of mass over the ocean, with a decrease in sea level compared to the global mean sea level contribution (GMSL) near the sources of mass added to the ocean and an increase up to 30% larger than the GMSL in the far field. The corresponding sea level fingerprints (SLF) are difficult to separate from ocean dynamics on short time and spatial scales but as ice melt continues, the SLF signal will become increasingly dominant in the pattern of regional sea level rise. It has been anticipated that it will be another few decades before the land ice SLF could be identified in the pattern of regional sea level rise. Here, we combine 40 years of observations of ice sheet mass balance for Antarctica (1975-present) and Greenland (1978-present), along with surface mass balance reconstructions of glacier and ice caps mass balance (GIC) from 1970s to present to determine the contribution to the SLF from melting land ice (MAR and RACMO). We compare the results with observations from GRACE for the time period 2002 to present for evaluation of our approach. Land hydrology is constrained by GRACE data for the period 2002-present and by the GLDAS-NOAH land hydrology model for the longer time period. Over the long time period, we find that the contribution from land ice dominates. We quantify the contribution to the total SLF from Greenland and Antarctica in various parts of the world over the past 40 years. More important, we compare the cumulative signal from SLF with tide gauge records around the world, corrected for earth dynamics, to determine whether the land ice SLF can be detected in that record. Early results will be reported at the meeting. This work was performed at UC Irvine and at Caltech's Jet Propulsion Laboratory under a contract with NASA's Cryospheric Science Program.

Trends in Arctic Ocean bottom pressure, sea surface height and freshwater content using GRACE and the ice-ocean model PIOMAS from 2008-2012

Science.gov (United States)

Peralta-Ferriz, Cecilia; Morison, James; Zhang, Jinlun; Bonin, Jennifer

2014-05-01

The variability of ocean bottom pressure (OBP) in the Arctic is dominated by the variations in sea surface height (SSH) from daily to monthly timescales. Conversely, OBP variability is dominated by the changes in the steric pressure (StP) at inter-annual timescales, particularly off the continental shelves. The combination of GRACE-derived ocean bottom pressure and ICESat altimetry-derived sea surface height variations in the Arctic Ocean have provided new means of identifying inter-annual trends in StP (StP = OBP-SSH) and associated freshwater content (FWC) of the Arctic region (Morison et al., 2012). Morison et al. (2012) showed that from 2004 to 2008, the FWC increased in the Beaufort Gyre and decreased in the Siberian and Central Arctic, resulting in a relatively small net basin-averaged FWC change. In this work, we investigate the inter-annual trends from 2008 to 2012 in OBP from GRACE, SSH from the state-of-the-art pan-Arctic ocean model PIOMAS -validated with tide and pressure gauges in the Arctic-, and compute the trends in StP and FWC from 2008-2012. We compare these results with the previous trends from 2005-2008 described in Morison et al. (2012). Our initial findings suggest increased salinity in the entire Arctic basin (relative to the climatological seasonal variation) from 2008-2012, compared to the preceding four years (2005-2008). We also find that the trends in OBP, SSH and StP from 2008-2012 present a different behavior during the spring-summer and fall-winter, unlike 2005-2008, in which the trends were generally consistent through all months of the year. It seems since 2009, when the Beaufort Gyre relaxed and the export of freshwater from the Canada Basin into the Canadian Archipelago and Fram Strait, via the Lincoln Sea, was anomalously large (de Steur et al., 2013), the Arctic Ocean has entered a new circulation regime. The causes of such changes in the inter-annual trends of OBP, SSH and StP -hence FWC-, associated with the changes in the

Migrating pattern of deformation prior to the Tohoku-Oki earthquake revealed by GRACE data

Science.gov (United States)

Panet, Isabelle; Bonvalot, Sylvain; Narteau, Clément; Remy, Dominique; Lemoine, Jean-Michel

2018-05-01

Understanding how and when far-field continuous motions lead to giant subduction earthquakes remains a challenge. An important limitation comes from an incomplete description of aseismic mass fluxes at depth along plate boundaries. Here we analyse Earth's gravity field variations derived from GRACE satellite data in a wide space-time domain surrounding the Mw 9.0 2011 Tohoku-Oki earthquake. We show that this earthquake is the extreme expression of initially silent deformation migrating from depth to the surface across the entire subduction system. Our analysis indeed reveals large-scale gravity and mass changes throughout three tectonic plates and connected slabs, starting a few months before March 2011. Before the Tohoku-Oki earthquake rupture, the gravity variations can be explained by aseismic extension of the Pacific plate slab at mid-upper mantle depth, concomitant with increasing seismicity in the shallower slab. For more than two years after the rupture, the deformation propagated far into the Pacific and Philippine Sea plate interiors, suggesting that subduction accelerated along 2,000 km of the plate boundaries in March 2011. This gravitational image of the earthquake's long-term dynamics provides unique information on deep and crustal processes over intermediate timescales, which could be used in seismic hazard assessment.

GRACE gravity field modeling with an investigation on correlation between nuisance parameters and gravity field coefficients

Science.gov (United States)

Zhao, Qile; Guo, Jing; Hu, Zhigang; Shi, Chuang; Liu, Jingnan; Cai, Hua; Liu, Xianglin

2011-05-01

The GRACE (Gravity Recovery And Climate Experiment) monthly gravity models have been independently produced and published by several research institutions, such as Center for Space Research (CSR), GeoForschungsZentrum (GFZ), Jet Propulsion Laboratory (JPL), Centre National d’Etudes Spatiales (CNES) and Delft Institute of Earth Observation and Space Systems (DEOS). According to their processing standards, above institutions use the traditional variational approach except that the DEOS exploits the acceleration approach. The background force models employed are rather similar. The produced gravity field models generally agree with one another in the spatial pattern. However, there are some discrepancies in the gravity signal amplitude between solutions produced by different institutions. In particular, 10%-30% signal amplitude differences in some river basins can be observed. In this paper, we implemented a variant of the traditional variational approach and computed two sets of monthly gravity field solutions using the data from January 2005 to December 2006. The input data are K-band range-rates (KBRR) and kinematic orbits of GRACE satellites. The main difference in the production of our two types of models is how to deal with nuisance parameters. This type of parameters is necessary to absorb low-frequency errors in the data, which are mainly the aliasing and instrument errors. One way is to remove the nuisance parameters before estimating the geopotential coefficients, called NPARB approach in the paper. The other way is to estimate the nuisance parameters and geopotential coefficients simultaneously, called NPESS approach. These two types of solutions mainly differ in geopotential coefficients from degree 2 to 5. This can be explained by the fact that the nuisance parameters and the gravity field coefficients are highly correlated, particularly at low degrees. We compare these solutions with the official and published ones by means of spectral analysis. It is

On Land Ice Mass Change in Southernmost South America, Antarctic Peninsula and Coastal Antarctica consistent with GRACE, GPS and Reconstructed Ice History for Past 1000 years.

Science.gov (United States)

Ivins, Erik; Wiese, David; Watkins, Michael; Yuan, Dah-Ning; Landerer, Felix; Simms, Alex; Boening, Carmen

2014-05-01

The improved spatial coverage provided by high-quality Global Positioning System observing systems on exposed bedrock has allowed these space geodetic experiments to play an increasingly important role in constraining both glacial isostatic adjustment (GIA) processes and viscoelastic responses to present-day glacial mass changes (PGMC). Improved constraints on models of ice mass change in the Southern Hemisphere at present-day, during the Little Ice Age, and during the Late Holocene are invaluable for reconciling climate and sea-level variability on a global scale during the present solar radiation forcing and Milankovic orbital configuration. Studies by Jacobs et al. (1992), Whitehouse et al. (2012), King et al. (2012), Boening et al (2012), and others, support the contention that GRACE observations of both GIA and PGMC in the Southern Hemisphere are dominated by the geography and climate of coastal environments. This makes the proper masking of those environments for GRACE-determinations of secular mass balance especially sensitive, and downscaling, rescaling, and use of correlation mascon methods a non-trivial part of the analysis. Here we employ two analysis methods to determine the mass balances of the Antarctic Peninsula and Patagonia and incorporate GPS observations of ongoing uplift for GIA correction into both. Using data that roughly span 2002-2013, we determine -25 ± 5 Gt/yr for the uncorrected Antarctic Peninsula (AP) and -12 Gt/yr for southern Patagonia and the Cordillera Darwin (PCD). With corrections for GIA these are increased to -34 ± 8 Gt/yr for AP and -22 ± 6 Gt/yr for PCD.

Antarctic Peninsula mass balance at present-day and over the past 150 years employing constraints from GRACE, GPS and other data

Science.gov (United States)

Ivins, E. R.; Wiese, D. N.; Watkins, M. M.; Landerer, F. W.; Simms, A.; Yuan, D.; Boening, C.

2013-12-01

Warming on the Antarctic Peninsula (AP) land mass and adjacent islands has been ocurring for more than 100 years. The rate of warming is at the extreme end of all Earth observations: during the 2nd half of the 20th century the rate is 3.5°C per century and has a dramatic effect of glaciers: west coast glaciers show diminishing outlet heights at a rate of 0.28 × 0.03 m/yr since the mid-1960s (Kunz et al., 2012). Since the late 1980's, notably on the northeastern edge of the AP, many of the outlet glaciers have experienced the loss of ice shelf buttressing forces that retard the outlet flow velocity (e.g., Berthier et al., 2012). The loss of these buttressing forces has caused outlet glaciers to speed up. It is clear from ice core and in situ records that the AP snow accumulation has also been increasing. While there is growing confidence that all space borne data are consistent with a net mass loss of the Antarctic Peninsula since 1990, there is relatively little convergence on the total mass loss, and its temporal variability, other than that measured by the Gravity Recovery and Climate Experiment (GRACE). Employing JPL mascon analyses, Ivins et al. (2011) employed 6.25 years of GRACE data, glacial isostatic adjustment (GIA) modeling with GPS data, to determine the mass trend of Graham Land (north of 67° S) at -32 × 6 Gt/yr and -9.5 × 3 Gt/yr for the remainder of the AP (74° S - 67° S). Neither region exhibited any significant non-secular signatures during 2003-2009.25. However, some outlet glaciers have shown both height and velocity changes over the period 2002-2012 that indicate increasing rates of loss - via laser altimetry and InSAR measurements (Anya Wendt, personal communication, 2012). In a combined examination of AP mass balance (with a slightly larger area for AP definition), recent work extended to mid 2013, indicates that the region of the Antarctic Peninsula has a loss rate of about -32.5 × 12 Gt/yr, with distinct and significant speed-up after

Full O(α) electroweak radiative corrections to e+e- → t anti t γ with GRACE-Loop

International Nuclear Information System (INIS)

Khiem, P.H.; Fujimoto, J.; Ishikawa, T.; Kaneko, T.; Kurihara, Y.; Shimizu, Y.; Kato, K.; Ueda, T.; Vermaseren, J.A.M.; Yasui, Y.

2013-01-01

We present the full O(α) electroweak radiative corrections to the process e + e - → t anti t γ at the International Linear Collider (ILC). The computation is performed with the help of the GRACE-Loop system. We present the total cross-section and the top quark forward-backward asymmetry (A FB ) as a function of the center-of-mass energy and compare them with the process e + e - → t anti t γ. We find that the value of A FB in t anti t γ production is larger than A FB in t anti t production. It is an important result for the measurement of the top quark forward-backward asymmetry at the ILC. Applying a structure function method, we also subtract the QED correction to gain the genuine weak correction in both the α scheme and the G μ scheme (δ W G μ ). We obtain numerical values for δ W G μ which are changing from 2 % to -24 % when we vary the center-of-mass energy from 360 GeV to 1 TeV. (orig.)

Water Budget Closure Based on GRACE Measurements and Reconstructed Evapotranspiration Using GLDAS and Water Use Data over the Yellow River and Changjiang River Basins

Science.gov (United States)

Lv, M.; Ma, Z.; Yuan, X.

2017-12-01

It is important to evaluate the water budget closure on the basis of the currently available data including precipitation, evapotranspiration (ET), runoff, and GRACE-derived terrestrial water storage change (TWSC) before using them to resolve water-related issues. However, it remains challenging to achieve the balance without the consideration of human water use (e.g., inter-basin water diversion and irrigation) for the estimation of other water budget terms such as the ET. In this study, the terrestrial water budget closure is tested over the Yellow River Basin (YRB) and Changjiang River Basin (CJB, Yangtze River Basin) of China. First, the actual ET is reconstructed by using the GLDAS-1 land surface models, the high quality observation-based precipitation, naturalized streamflow, and the irrigation water (hereafter, ETrecon). The ETrecon, evaluated using the mean annual water-balance equation, is of good quality with the absolute relative errors less than 1.9% over the two studied basins. The total basin discharge (Rtotal) is calculated as the residual of the water budget among the observation-based precipitation, ETrecon, and the GRACE-TWSC. The value of the Rtotal minus the observed total basin discharge is used to evaluate the budget closure, with the consideration of inter-basin water diversion. After the ET reconstruction, the mean absolute imbalance value reduced from 3.31 cm/year to 1.69 cm/year and from 15.40 cm/year to 1.96 cm/year over the YRB and CJB, respectively. The estimation-to-observation ratios of total basin discharge improved from 180.8% to 86.8% over the YRB, and from 67.0% to 101.1% over the CJB. The proposed ET reconstruction method is applicable to other human-managed river basins to provide an alternative estimation.

From grass to grace: How SLMTA revolutionised the Bamenda Regional Hospital Laboratory in Cameroon

Directory of Open Access Journals (Sweden)

Siyem C. Nkwawir

2014-11-01

Objectives: To evaluate the results of SLMTA implementation at BRHL and discuss lessons learned. Method: In 2010, the SLMTA programme was rolled out in Cameroon to improve laboratory quality management systems in five laboratories, including BRHL. Three workshops were conducted (the first centralised, the remaining two on-site at each laboratory and improvement projects were implemented after each workshop with the assistance of mentors. Audits were used in order to evaluate performance and to identify areas for further improvement. Results: BRHL had the lowest score (18% amongst the cohort at the baseline audit and the highest (81% at the official Stepwise Laboratory Quality Improvement Process Towards Accreditation (SLIPTA audit conducted in August 2013 by the African Society for Laboratory Medicine. Improvements were observed in each of the 12 Quality System Essentials; improvement was especially noteworthy in the areas of facilities and safety, and purchasing and inventory. Staff investment and pride in the quality of laboratory services increased. Conclusion: BRHL’s remarkable improvement was achieved with a combination of SLMTA training activities, intensive on-site mentorship and the collective focus of all laboratory staff. The experience at Bamenda Hospital illustrates what can be achieved when a laboratory successfully harnesses the energy of its staff and implements changes to improve the quality of services in a transformation taking them from grass to grace.

Graceful Degradation in 3GPP MBMS Mobile TV Services Using H.264/AVC Temporal Scalability

Directory of Open Access Journals (Sweden)

Thomas Wiegand

2009-01-01

Full Text Available These days, there is an increasing interest in Mobile TV broadcast services shown by customers as well as service providers. One general problem of Mobile TV broadcast services is to maximize the coverage of users receiving an acceptable service quality, which is mainly influenced by the user's position and mobility within the cell. In this paper, graceful degradation is considered as an approach for improved service availability and coverage. We present a layered transmission approach for 3GPP's Release 6 Multimedia and Broadcast Service (MBMS based on temporal scalability using H.264/AVC Baseline Profile. A differentiation in robustness between temporal quality layers is achieved by unequal error protection approach based on either application layer Forward Error Correction (FEC or unequal transmit power for the layers or even a combination of both. We discuss the corresponding MBMS service as well as network settings and define measures allowing for evaluating the amount of users reached with a certain mobile terminal play-out quality while considering the network cell capacity usage. Using simulated 3GPP Rel. 6 network conditions, we show that if the service and network settings are chosen carefully, a noticeable extension of the coverage of the MBMS service can be achieved.

Investigating the Origin of Natural and Anthropogenic Deformation across the Nile Delta Using Radar Interferometry, GRACE, Modeling, and Field data

Science.gov (United States)

Gebremichael, E.; Sultan, M.; Becker, R.; El Bastawesy, M.; Cherif, O.; Emil, M.; Ahmed, M.; Fathy, K.; Karki, S.; Chouinard, K.

2016-12-01

We applied an integrated approach (radar interferometry, flood simulation, GRACE, GIS) to investigate the nature and distribution of land deformation in the Nile Delta and to identify the natural and anthropogenic controlling factors. Our methodology involved: (1) applying persistent scatterer interferometry (PSI) across the entire Delta (scenes: 108 level 0 scenes; Tracks: 4 tracks; time period: 2003-2010); (2) correcting the interferometry output for various phase contributing errors (e.g., atmosphere, orbit, etc.) and calibrating/validating the output against 3 GNSS GPS stations (2 in Alexandria, 1 in Helwan); (3) conducting spatial correlation (in a GIS environment) of the radar outputs with relevant remote sensing, subsurface, and geologic datasets; (4) simulating flood depth and inundation to investigate the spatial extent and depth of the Holocene sediments using the HEC-RAS software (inputs: DEM and monthly discharge data; period: 1871-1902), (5) identifying subsurface structures by processing 712 gridded field gravity data points in Geosoft Oasis Montaj software (Bouguer anomaly analysis), and (6) analyzing monthly (2002-2015) GRACE-derived TWS solutions (0.5° x 0.5° CSR mascons). Our findings include: (1) three main structural trends (E-W, NW-SE and NE-SW trending) were mapped across the Delta, (2) areas of high subsidence coincide with the distribution of relatively thick recent sediments (<3000 years), probably due to sediment compaction, in three settings: (a) areas susceptible to flooding from the Damietta and Rosetta branches (e.g., east Damietta branch; latitude 30.8° to 31.2°; longitude 31.2° to 31.6°), (b) areas susceptible to sediment deposition at bifurcation locations of primary channels (e.g., near Cairo) and, (c) areas where mapped faults intersect Damietta and Rosetta channels, change their course, and cause ponding of surface water and sediment deposition, (3) extraction of gas from the Abu Madi gas field in north central delta

Rapid detection of pathological mutations and deletions of the haemoglobin beta gene (HBB) by High Resolution Melting (HRM) analysis and Gene Ratio Analysis Copy Enumeration PCR (GRACE-PCR).

Science.gov (United States)

Turner, Andrew; Sasse, Jurgen; Varadi, Aniko

2016-10-19

Inherited disorders of haemoglobin are the world's most common genetic diseases, resulting in significant morbidity and mortality. The large number of mutations associated with the haemoglobin beta gene (HBB) makes gene scanning by High Resolution Melting (HRM) PCR an attractive diagnostic approach. However, existing HRM-PCR assays are not able to detect all common point mutations and have only a very limited ability to detect larger gene rearrangements. The aim of the current study was to develop a HBB assay, which can be used as a screening test in highly heterogeneous populations, for detection of both point mutations and larger gene rearrangements. The assay is based on a combination of conventional HRM-PCR and a novel Gene Ratio Analysis Copy Enumeration (GRACE) PCR method. HRM-PCR was extensively optimised, which included the use of an unlabelled probe and incorporation of universal bases into primers to prevent interference from common non-pathological polymorphisms. GRACE-PCR was employed to determine HBB gene copy numbers relative to a reference gene using melt curve analysis to detect rearrangements in the HBB gene. The performance of the assay was evaluated by analysing 410 samples. A total of 44 distinct pathological genotypes were detected. In comparison with reference methods, the assay has a sensitivity of 100 % and a specificity of 98 %. We have developed an assay that detects both point mutations and larger rearrangements of the HBB gene. This assay is quick, sensitive, specific and cost effective making it suitable as an initial screening test that can be used for highly heterogeneous cohorts.

A test of general relativity using the LARES and LAGEOS satellites and a GRACE Earth gravity model: Measurement of Earth's dragging of inertial frames.

Science.gov (United States)

Ciufolini, Ignazio; Paolozzi, Antonio; Pavlis, Erricos C; Koenig, Rolf; Ries, John; Gurzadyan, Vahe; Matzner, Richard; Penrose, Roger; Sindoni, Giampiero; Paris, Claudio; Khachatryan, Harutyun; Mirzoyan, Sergey

2016-01-01

We present a test of general relativity, the measurement of the Earth's dragging of inertial frames. Our result is obtained using about 3.5 years of laser-ranged observations of the LARES, LAGEOS, and LAGEOS 2 laser-ranged satellites together with the Earth gravity field model GGM05S produced by the space geodesy mission GRACE. We measure [Formula: see text], where [Formula: see text] is the Earth's dragging of inertial frames normalized to its general relativity value, 0.002 is the 1-sigma formal error and 0.05 is our preliminary estimate of systematic error mainly due to the uncertainties in the Earth gravity model GGM05S. Our result is in agreement with the prediction of general relativity.

Project GRACE: a staged approach to development of a community-academic partnership to address HIV in rural African American communities.

Science.gov (United States)

Corbie-Smith, Giselle; Adimora, Adaora A; Youmans, Selena; Muhammad, Melvin; Blumenthal, Connie; Ellison, Arlinda; Akers, Aletha; Council, Barbara; Thigpen, Yolanda; Wynn, Mysha; Lloyd, Stacey W

2011-03-01

The HIV epidemic is a health crisis in rural African American communities in the Southeast United States; however, to date little attention has been paid to community-academic collaborations to address HIV in these communities. Interventions that use a community-based participatory research (CBPR) approach to address individual, social, and physical environmental factors have great potential for improving community health. Project GRACE (Growing, Reaching, Advocating for Change and Empowerment) uses a CBPR approach to develop culturally sensitive, feasible, and sustainable interventions to prevent the spread of HIV in rural African American communities. This article describes a staged approach to community-academic partnership: initial mobilization, establishment of organizational structure, capacity building for action, and planning for action. Strategies for engaging rural community members at each stage are discussed; challenges faced and lessons learned are also described. Careful attention to partnership development has resulted in a collaborative approach that has mutually benefited both the academic and community partners.

Seasonal variations in shallow Alaska seismicity and stress modulation from GRACE derived hydrological loading

Science.gov (United States)

Johnson, C. W.; Fu, Y.; Burgmann, R.

2017-12-01

Shallow (≤50 km), low magnitude (M≥2.0) seismicity in southern Alaska is examined for seasonal variations during the annual hydrological cycle. The seismicity is declustered with a spatio-temporal epidemic type aftershock sequence (ETAS) model. The removal of aftershock sequences allows detailed investigation of seismicity rate changes, as water and ice loads modulate crustal stresses throughout the year. The GRACE surface loads are obtained from the JPL mass concentration blocks (mascons) global land and ocean solutions. The data product is smoothed with a 9˚ Gaussian filter and interpolated on a 25 km grid. To inform the surface loading model, the global solutions are limited to the region from -160˚ to -120˚ and 50˚ to 70˚. The stress changes are calculated using a 1D spherical layered earth model at depth intervals of 10 km from 10 - 50 km in the study region. To evaluate the induced seasonal stresses, we use >30 years of earthquake focal mechanisms to constrain the background stress field orientation and assess the stress change with respect to the principal stress orientation. The background stress field is assumed to control the preferred orientation of faulting, and stress field perturbations are expected to increase or decrease seismicity. The number of excess earthquakes is calculated with respect to the background seismicity rates. Here, we present preliminary results for the shallow seismicity variations and quantify the seasonal stresses associated with changes in hydrological loading.

Tidal signatures of the thermospheric mass density and zonal wind at midlatitude: CHAMP and GRACE observations

Directory of Open Access Journals (Sweden)

C. Xiong

2015-02-01

Full Text Available By using the accelerometer measurements from CHAMP and GRACE satellites, the tidal signatures of the thermospheric mass density and zonal wind at midlatitudes have been analyzed in this study. The results show that the mass density and zonal wind at southern midlatitudes are dominated by a longitudinal wave-1 pattern. The most prominent tidal components in mass density and zonal wind are the diurnal tides D0 and DW2 and the semidiurnal tides SW1 and SW3. This is consistent with the tidal signatures in the F region electron density at midlatitudes as reported by Xiong and Lühr (2014. These same tidal components are observed both in the thermospheric and ionospheric quantities, supporting a mechanism that the non-migrating tides in the upper atmosphere are excited in situ by ion–neutral interactions at midlatitudes, consistent with the modeling results of Jones Jr. et al. (2013. We regard the thermospheric dynamics as the main driver for the electron density tidal structures. An example is the in-phase variation of D0 between electron density and mass density in both hemispheres. Further research including coupled atmospheric models is probably needed for explaining the similarities and differences between thermospheric and ionospheric tidal signals at midlatitudes.

Characterization of Terrestrial Water Dynamics in the Congo Basin Using GRACE and Satellite Radar Altimetry

Science.gov (United States)

Lee, Lyongki; Beighley, R. Edward; Alsdorf, Douglas; Jung, Hahn Chul; Shum, C. K.; Duan, Jianbin; Guo, Junyi; Yamazaki, Dai; Andreadis, Konstantinos

2011-01-01

The Congo Basin is the world's third largest in size (approximately 3.7 million km^2), and second only to the Amazon River in discharge (approximately 40,200 cms annual average). However, the hydrological dynamics of seasonally flooded wetlands and floodplains remains poorly quantified. Here, we separate the Congo wetland into four 3 degree x 3 degree regions, and use remote sensing measurements (i.e., GRACE, satellite radar altimeter, GPCP, JERS-1, SRTM, and MODIS) to estimate the amounts of water filling and draining from the Congo wetland, and to determine the source of the water. We find that the amount of water annually filling and draining the Congo wetlands is 111 km^3, which is about one-third the size of the water volumes found on the mainstem Amazon floodplain. Based on amplitude comparisons among the water volume changes and timing comparisons among their fluxes, we conclude that the local upland runoff is the main source of the Congo wetland water, not the fluvial process of river-floodplain water exchange as in the Amazon. Our hydraulic analysis using altimeter measurements also supports our conclusion by demonstrating that water surface elevations in the wetlands are consistently higher than the adjacent river water levels. Our research also highlights differences in the hydrology and hydrodynamics between the Congo wetland and the mainstem Amazon floodplain.

Modeling of Thermospheric Neutral Density Variations in Response to Geomagnetic Forcing using GRACE Accelerometer Data

Science.gov (United States)

Calabia, A.; Matsuo, T.; Jin, S.

2017-12-01

The upper atmospheric expansion refers to an increase in the temperature and density of Earth's thermosphere due to increased geomagnetic and space weather activities, producing anomalous atmospheric drag on LEO spacecraft. Increased drag decelerates satellites, moving their orbit closer to Earth, decreasing the lifespan of satellites, and making satellite orbit determination difficult. In this study, thermospheric neutral density variations due to geomagnetic forcing are investigated from 10 years (2003-2013) of GRACE's accelerometer-based estimates. In order to isolate the variations produced by geomagnetic forcing, 99.8% of the total variability has been modeled and removed through the parameterization of annual, LST, and solar-flux variations included in the primary Empirical Orthogonal Functions. The residual disturbances of neutral density variations have been investigated further in order to unravel their relationship to several geomagnetic indices and space weather activity indicators. Stronger fluctuations have been found in the southern polar cap, following the dipole-tilt angle variations. While the parameterization of the residual disturbances in terms of Dst index results in the best fit to training data, the use of merging electric field as a predictor leads to the best forecasting performance. An important finding is that modeling of neutral density variations in response geomagnetic forcing can be improved by accounting for the latitude-dependent delay. Our data-driven modeling results are further compared to modeling with TIEGCM.

Zadig: latest improvements to Bremsstrahlung treatment and in-flight annihilation scheme; Zadig: amelioration du traitement Bremsstrahlung et traitement de l'annihilation en vol

Energy Technology Data Exchange (ETDEWEB)

Menard, St

2006-07-01

Multigroup cross-section for the 3-dimensional Monte-Carlo transport code DIANE are produced by the ZADIG code. Although DIANE does not transport the electrons and positrons, the production of Bremsstrahlung photons induced by the electrons and positrons during their slowing down is taken into account in the ZADIG code because the electron-gamma cascade is an important process in high energy gamma ray transport. ZADIG does not distinguish positrons from electrons except for the positron annihilation. However, the user can turn on this direction. This report presents the latest improvements to the Bremsstrahlung model of ZADIG and to the positron annihilation algorithm implemented in the code. Positrons can annihilate either in flight or at rest in the latest release of ZADIG. As MCNP does not take into account the annihilation in flight, results of ZADIG-DIANE calculations are compared to the results of GEANT-4 in order to validate the annihilation scheme of ZADIG. The results with annihilation divided by the results without present similar trends between 0.6 and 10 MeV for the 2 codes (GEANT-4 and ZADIG-DIANE), in other words an influence of 5%, so the annihilation scheme programmed in ZADIG appears to be satisfying and can be considered as validated.

Distributed analysis environment for HEP and interdisciplinary applications

International Nuclear Information System (INIS)

Moscicki, J.T.

2003-01-01

Huge data volumes of Larger Hadron Collider experiment require parallel end-user analysis on clusters of hundreds of machines. While the focus of end-user High-Energy Physics analysis is on ntuples, the master-worker model of parallel processing may be also used in other contexts such as detector simulation. The aim of DIANE R and D project (http://cern.ch/it-proj-diane) currently held by CERN IT/API group is to create a generic, component-based framework for distributed, parallel data processing in master-worker model. Pre-compiled user analysis code is loaded dynamically at runtime in component libraries and called back when appropriate. Such application-oriented framework must be flexible enough to integrate with the emerging GRID technologies as they become available in the time to come. Therefore, common services such as environment reconstruction, code distribution, load balancing and authentication are designed and implemented as pluggable modules. This approach allows to easily replace them with modules implemented with newer technology as necessary. The paper gives an overview of DIANE architecture and explains the main design choices. Selected examples of diverse applications from a variety of domains applicable to DIANE are presented. As well as preliminary benchmarking results

1392-IJBCS-Article-Diane Kpogue

African Journals Online (AJOL)

KODJIO NORBERT

potential, a high economic value and represents a good potential ... anthropogenic activities leading to siltation, ... systems and effluent production in flow- through ... put in circular tank. Before the ..... Ministry of Higher Education and Scientific.

1267-IJBCS-Article-Diane Kpogue

African Journals Online (AJOL)

hp

. Fishing News Books: Oxford; 575 p. Reddy SR, Katre S. 1979. Growth rate and conversion efficiency of the air-breathing catfish, Heteropneustes fossilis, in relation to ration size. Aquaculture, 18: 35-40. Reinitz G. 1983a. Relative effect of age, ...

Large-Scale Total Water Storage and Water Flux Changes over the Arid and Semiarid Parts of the Middle East from GRACE and Reanalysis Products

Science.gov (United States)

Forootan, E.; Safari, A.; Mostafaie, A.; Schumacher, M.; Delavar, M.; Awange, J. L.

2017-05-01

Previous studies indicate that water storage over a large part of the Middle East has been decreased over the last decade. Variability in the total (hydrological) water flux (TWF, i.e., precipitation minus evapotranspiration minus runoff) and water storage changes of the Tigris-Euphrates river basin and Iran's six major basins (Khazar, Persian, Urmia, Markazi, Hamun, and Sarakhs) over 2003-2013 is assessed in this study. Our investigation is performed based on the TWF that are estimated as temporal derivatives of terrestrial water storage (TWS) changes from the Gravity Recovery and Climate Experiment (GRACE) products and those from the reanalysis products of ERA-Interim and MERRA-Land. An inversion approach is applied to consistently estimate the spatio-temporal changes of soil moisture and groundwater storage compartments of the seven basins during the study period from GRACE TWS, altimetry, and land surface model products. The influence of TWF trends on separated water storage compartments is then explored. Our results, estimated as basin averages, indicate negative trends in the maximums of TWF peaks that reach up to -5.2 and -2.6 (mm/month/year) over 2003-2013, respectively, for the Urmia and Tigris-Euphrates basins, which are most likely due to the reported meteorological drought. Maximum amplitudes of the soil moisture compartment exhibit negative trends of -11.1, -6.6, -6.1, -4.8, -4.7, -3.8, and -1.2 (mm/year) for Urmia, Tigris-Euphrates, Khazar, Persian, Markazi, Sarakhs, and Hamun basins, respectively. Strong groundwater storage decrease is found, respectively, within the Khazar -8.6 (mm/year) and Sarakhs -7.0 (mm/year) basins. The magnitude of water storage decline in the Urmia and Tigris-Euphrates basins is found to be bigger than the decrease in the monthly accumulated TWF indicating a contribution of human water use, as well as surface and groundwater flow to the storage decline over the study area.

Combining satellite radar altimetry, SAR surface soil moisture and GRACE total storage changes for hydrological model calibration in a large poorly gauged catchment

DEFF Research Database (Denmark)

Milzow, Christian; Krogh, Pernille Engelbredt; Bauer-Gottwein, Peter

2011-01-01

The availability of data is a major challenge for hydrological modelling in large parts of the world. Remote sensing data can be exploited to improve models of ungauged or poorly gauged catchments. In this study we combine three datasets for calibration of a rainfall-runoff model of the poorly...... gauged Okavango catchment in Southern Africa: (i) surface soil moisture (SSM) estimates derived from radar measurements onboard the Envisat satellite; (ii) radar altimetry measurements by Envisat providing river stages in the tributaries of the Okavango catchment, down to a minimum river width of about...... one hundred meters; and (iii) temporal changes of the Earth's gravity field recorded by the Gravity Recovery and Climate Experiment (GRACE) caused by total water storage changes in the catchment. The SSM data are shown to be helpful in identifying periods with over-respectively underestimation...

Long Range River Discharge Forecasting Using the Gravity Recovery and Climate Experiment (GRACE) Satellite to Predict Conditions for Endemic Cholera

Science.gov (United States)

Jutla, A.; Akanda, A. S.; Colwell, R. R.

2014-12-01

Prediction of conditions of an impending disease outbreak remains a challenge but is achievable if the associated and appropriate large scale hydroclimatic process can be estimated in advance. Outbreaks of diarrheal diseases such as cholera, are related to episodic seasonal variability in river discharge in the regions where water and sanitation infrastructure are inadequate and insufficient. However, forecasting river discharge, few months in advance, remains elusive where cholera outbreaks are frequent, probably due to non-availability of geophysical data as well as transboundary water stresses. Here, we show that satellite derived water storage from Gravity Recovery and Climate Experiment Forecasting (GRACE) sensors can provide reliable estimates on river discharge atleast two months in advance over regional scales. Bayesian regression models predicted flooding and drought conditions, a prerequisite for cholera outbreaks, in Bengal Delta with an overall accuracy of 70% for upto 60 days in advance without using any other ancillary ground based data. Forecasting of river discharge will have significant impacts on planning and designing intervention strategies for potential cholera outbreaks in the coastal regions where the disease remain endemic and often fatal.

Combining satellite radar altimetry, SAR surface soil moisture and GRACE total storage changes for model calibration and validation in a large ungauged catchment

DEFF Research Database (Denmark)

Milzow, Christian; Krogh, Pernille Engelbredt; Bauer-Gottwein, Peter

2010-01-01

The availability of data is a major challenge for hydrological modelling in large parts of the world. Remote sensing data can be exploited to improve models of ungauged or poorly gauged catchments. In this study we combine three datasets for calibration and validation of a rainfall-runoff model...... of the ungauged Okavango catchment in Southern Africa: (i) Surface soil moisture (SSM) estimates derived from SAR measurements onboard the Envisat satellite; (ii) Radar altimetry measurements by Envisat providing river stages in the tributaries of the Okavango catchment, down to a minimum width of about one...... hundred meters; and (iii) Temporal changes of the Earth’s gravity field recorded by the Gravity Recovery and Climate Experiment (GRACE) caused by total water storage changes in the catchment. The SSM data are compared to simulated moisture conditions in the top soil layer. They cannot be used for model...

Monthly gravity field solutions based on GRACE observations generated with the Celestial Mechanics Approach

Science.gov (United States)

Meyer, Ulrich; Jäggi, Adrian; Beutler, Gerhard

2012-09-01

The main objective of the Gravity Recovery And Climate Experiment (GRACE) satellite mission consists of determining the temporal variations of the Earth's gravity field. These variations are captured by time series of gravity field models of limited resolution at, e.g., monthly intervals. We present a new time series of monthly models, which was computed with the so-called Celestial Mechanics Approach (CMA), developed at the Astronomical Institute of the University of Bern (AIUB). The secular and seasonal variations in the monthly models are tested for statistical significance. Calibrated errors are derived from inter-annual variations. The time-variable signal can be extracted at least up to degree 60, but the gravity field coefficients of orders above 45 are heavily contaminated by noise. This is why a series of monthly models is computed up to a maximum degree of 60, but only a maximum order of 45. Spectral analysis of the residual time-variable signal shows a distinctive peak at a period of 160 days, which shows up in particular in the C20 spherical harmonic coefficient. Basic filter- and scaling-techniques are introduced to evaluate the monthly models. For this purpose, the variability over the oceans is investigated, which serves as a measure for the noisiness of the models. The models in selected regions show the expected seasonal and secular variations, which are in good agreement with the monthly models of the Helmholtz Centre Potsdam, German Research Centre for Geosciences (GFZ). The results also reveal a few small outliers, illustrating the necessity for improved data screening. Our monthly models are available at the web page of the International Centre for Global Earth Models (ICGEM).

A test of general relativity using the LARES and LAGEOS satellites and a GRACE Earth gravity model. Measurement of Earth's dragging of inertial frames

Energy Technology Data Exchange (ETDEWEB)

Ciufolini, Ignazio [Universita del Salento, Dipartimento Ingegneria dell' Innovazione, Lecce (Italy); Sapienza Universita di Roma, Scuola di Ingegneria Aerospaziale, Rome (Italy); Paolozzi, Antonio; Paris, Claudio [Sapienza Universita di Roma, Scuola di Ingegneria Aerospaziale, Rome (Italy); Museo della Fisica e Centro Studi e Ricerche Enrico Fermi, Rome (Italy); Pavlis, Erricos C. [University of Maryland, Joint Center for Earth Systems Technology (JCET), Baltimore County (United States); Koenig, Rolf [GFZ German Research Centre for Geosciences, Helmholtz Centre Potsdam, Potsdam (Germany); Ries, John [University of Texas at Austin, Center for Space Research, Austin (United States); Gurzadyan, Vahe; Khachatryan, Harutyun; Mirzoyan, Sergey [Alikhanian National Laboratory and Yerevan State University, Center for Cosmology and Astrophysics, Yerevan (Armenia); Matzner, Richard [University of Texas at Austin, Theory Center, Austin (United States); Penrose, Roger [University of Oxford, Mathematical Institute, Oxford (United Kingdom); Sindoni, Giampiero [Sapienza Universita di Roma, DIAEE, Rome (Italy)

2016-03-15

We present a test of general relativity, the measurement of the Earth's dragging of inertial frames. Our result is obtained using about 3.5 years of laser-ranged observations of the LARES, LAGEOS, and LAGEOS 2 laser-ranged satellites together with the Earth gravity field model GGM05S produced by the space geodesy mission GRACE. We measure μ = (0.994 ± 0.002) ± 0.05, where μ is the Earth's dragging of inertial frames normalized to its general relativity value, 0.002 is the 1-sigma formal error and 0.05 is our preliminary estimate of systematic error mainly due to the uncertainties in the Earth gravity model GGM05S. Our result is in agreement with the prediction of general relativity. (orig.)

Exploring the entanglement of personal epistemologies and emotions in students' thinking

Science.gov (United States)

Gupta, Ayush; Elby, Andrew; Danielak, Brian A.

2018-06-01

Evidence from psychology, cognitive science, and neuroscience suggests that cognition and emotions are coupled. Education researchers have also documented correlations between emotions (such as joy, anxiety, fear, curiosity, boredom) and academic performance. Nonetheless, most research on students' reasoning and conceptual change within the learning sciences and physics and science education research has not attended to the role of learners' emotions in describing or modeling the fine timescale dynamics of their conceptual reasoning. The few studies that integrate emotions into models of learners' cognition have mostly done so at a coarse grain size. In this study, toward the long-term goal of incorporating emotions into models of in-the-moment cognitive dynamics, we present a case study of Judy, an undergraduate electrical engineering and physics major. We show that shifts in the intensity of a fine-grained aspect of Judy's emotions, her annoyance at conceptual homework problems, co-occur with shifts in her epistemological stance toward differentiating knowledge about and the practical utility of real circuits and idealized circuit models. We then argue for the plausibility of a cognitive model in which Judy's emotions and epistemological stances mutually affect each other. We end with discussions on how models of learners' cognition that incorporate their emotions are generative for instructional purposes and research on learning.

76 FR 40677 - Farm Service Agency

Science.gov (United States)

2011-07-11

... following methods: Mail: Judy Fry, Agricultural Marketing Specialist, Commodity Operations Division, Farm..., large print, audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice and TDD...

77 FR 43604 - National Institute of Allergy and Infectious Diseases (NIAID); Notice of Workshop

Science.gov (United States)

2012-07-25

... nuclear (CBRN) agents. With the convergence of scientific progress in medical countermeasures (MCMs... special accommodations due to a disability, please contact Dr. Judy Hewitt (see FOR FURTHER INFORMATION...

From Drought to Recovery: a GRACE-Based Assessment of Groundwater Storage Variations in California

Science.gov (United States)

McEvoy, A.; Famiglietti, J. S.; Liu, P. W.; Reager, J. T., II

2017-12-01

The 2011-2015 drought in California was the most severe on record and significantly depleted state water reserves. However, after the consecutive wet winters of 2015-16 and 2016-17, water storage in reservoirs, soil, snowpack, and aquifers began recovering and the state government lifted the drought emergency for all California counties except four. But is the drought really "over"? Quantifiable metrics of groundwater storage are necessary to provide such evidence, yet in situ measurements are sparse at best. Here we holistically test whether California state water resources have fully recovered in the Sacramento, San Joaquin, and Tulare Lake basins of California, using remote sensing satellite observations, in situ measurements, and numerical models. Specifically, we partition water storage into four components of the terrestrial water cycle: soil moisture, snow water equivalent, surface water, and groundwater. We derive soil moisture and snow water equivalent from the North American Land Data Assimilation System (NLDAS) and we use the California Data Exchange Center (CDEC) network to measure in situ reservoir storage. To estimate changes in groundwater storage, we subtract these three components from the total water storage derived from the Gravity Recovery and Climate Experiment (GRACE) satellite. Preliminary results show that the groundwater storage plummeted to a record low during the 2011-2015 drought. The results also show a rapid recovery in total water storage from 2015-2017. Moreover, we find that groundwater accounts for, on average, 60% of the total water storage variations in the study basins. Our results hold social significance when placed in the context of arid California: Did the groundwater recover? Is this the largest recovery that California can expect? Finally, our results have implications for the utility of remote sensing to inform water resource management decisions.

Inter-annual Variations in Snow/Firn Density over the Greenland Ice Sheet by Combining GRACE gravimetry and Envisat Altimetry

Science.gov (United States)

Su, X.; Shum, C. K.; Guo, J.; Howat, I.; Jezek, K. C.; Luo, Z.; Zhou, Z.

2017-12-01

Satellite altimetry has been used to monitor elevation and volume change of polar ice sheets since the 1990s. In order to derive mass change from the measured volume change, different density assumptions are commonly used in the research community, which may cause discrepancies on accurately estimating ice sheets mass balance. In this study, we investigate the inter-annual anomalies of mass change from GRACE gravimetry and elevation change from Envisat altimetry during years 2003-2009, with the objective of determining inter-annual variations of snow/firn density over the Greenland ice sheet (GrIS). High positive correlations (0.6 or higher) between these two inter-annual anomalies at are found over 93% of the GrIS, which suggests that both techniques detect the same geophysical process at the inter-annual timescale. Interpreting the two anomalies in terms of near surface density variations, over 80% of the GrIS, the inter-annual variation in average density is between the densities of snow and pure ice. In particular, at the Summit of Central Greenland, we validate the satellite data estimated density with the in situ data available from 75 snow pits and 9 ice cores. This study provides constraints on the currently applied density assumptions for the GrIS.

GestuRe and ACtion Exemplar (GRACE) video database: stimuli for research on manners of human locomotion and iconic gestures.

Science.gov (United States)

Aussems, Suzanne; Kwok, Natasha; Kita, Sotaro

2018-06-01

Human locomotion is a fundamental class of events, and manners of locomotion (e.g., how the limbs are used to achieve a change of location) are commonly encoded in language and gesture. To our knowledge, there is no openly accessible database containing normed human locomotion stimuli. Therefore, we introduce the GestuRe and ACtion Exemplar (GRACE) video database, which contains 676 videos of actors performing novel manners of human locomotion (i.e., moving from one location to another in an unusual manner) and videos of a female actor producing iconic gestures that represent these actions. The usefulness of the database was demonstrated across four norming experiments. First, our database contains clear matches and mismatches between iconic gesture videos and action videos. Second, the male actors and female actors whose action videos matched the gestures in the best possible way, perform the same actions in very similar manners and different actions in highly distinct manners. Third, all the actions in the database are distinct from each other. Fourth, adult native English speakers were unable to describe the 26 different actions concisely, indicating that the actions are unusual. This normed stimuli set is useful for experimental psychologists working in the language, gesture, visual perception, categorization, memory, and other related domains.

Determining water storage depletion within Iran by assimilating GRACE data into the W3RA hydrological model

Science.gov (United States)

Khaki, M.; Forootan, E.; Kuhn, M.; Awange, J.; van Dijk, A. I. J. M.; Schumacher, M.; Sharifi, M. A.

2018-04-01

Groundwater depletion, due to both unsustainable water use and a decrease in precipitation, has been reported in many parts of Iran. In order to analyze these changes during the recent decade, in this study, we assimilate Terrestrial Water Storage (TWS) data from the Gravity Recovery And Climate Experiment (GRACE) into the World-Wide Water Resources Assessment (W3RA) model. This assimilation improves model derived water storage simulations by introducing missing trends and correcting the amplitude and phase of seasonal water storage variations. The Ensemble Square-Root Filter (EnSRF) technique is applied, which showed stable performance in propagating errors during the assimilation period (2002-2012). Our focus is on sub-surface water storage changes including groundwater and soil moisture variations within six major drainage divisions covering the whole Iran including its eastern part (East), Caspian Sea, Centre, Sarakhs, Persian Gulf and Oman Sea, and Lake Urmia. Results indicate an average of -8.9 mm/year groundwater reduction within Iran during the period 2002 to 2012. A similar decrease is also observed in soil moisture storage especially after 2005. We further apply the canonical correlation analysis (CCA) technique to relate sub-surface water storage changes to climate (e.g., precipitation) and anthropogenic (e.g., farming) impacts. Results indicate an average correlation of 0.81 between rainfall and groundwater variations and also a large impact of anthropogenic activities (mainly for irrigations) on Iran's water storage depletions.

Hydrology in Central Europe - a Comparison Between Data from the GRACE Satellite Mission and Ground Superconducting Gravimeters

Science.gov (United States)

Crossley, D.; de Linage, C.; Boy, J.-P.; Hinderer, J.

2009-04-01

The surface gravity field is subject to many influences of mass redistribution within the Earth system, operating at the microgal (10-8 m s-2) level and at timescales from minutes to years. We include deformation within the Earth (tides, polar motion), motions within the atmosphere (local, regional, and global loading; also mass attractions), the oceans (non-tidal currents), and near-surface hydrology derived from rainfall (local, regional, and global contributions). In central Europe a network of 7 superconducting gravimeters (the only instrument with the required resolution for this type of work) has been operating for many years, recording variations at the sub-microgal level. Hydrology is the largest component in the un-modelled residual signal, most of which comes from an area within a few hundred m of the instrument. We use data from 2002-2007 to construct a regionalized ground gravity data set that is analyzed by Principal Component (EOF) analysis to extract the predominantly seasonal signal common to all stations. This we compare with the GRACE-derived field using solutions from GFZ Potsdam, CSR Texas, and GRGS Toulouse. There is very good agreement on the phase of the two different types of data, but the amplitude of the ground signal is complicated by the local hydrology around several of the stations, which is both above and below the instrument. We show our most recent analysis and compare the results with the GLDAS global hydrology model from NASA.

Amazing grace: Vancouver's supervised injection facility granted six-month lease on life

Directory of Open Access Journals (Sweden)

Small Dan

2008-01-01

the light of the scientific evidence, and lead the way towards to provision of a permanent medical exemption for injection facilities from Canada's Controlled Drugs and Substances Act (CDSA. In so doing, the Prime Minister would be on the brink of grace and would rescue a life saving health program from perpetual political interference.

78 FR 58458 - Drawbridge Operation Regulations; Quogue Canal, Southampton, NY

Science.gov (United States)

2013-09-24

... INFORMATION CONTACT: If you have questions on this rule, call or email Ms. Judy Leung-Yee, Project Officer, First Coast Guard District, telephone (212) 668-7165, email [email protected] . If you have...

77 FR 6012 - Drawbridge Operation Regulations; Hutchinson River (Eastchester Creek), Bronx, NY

Science.gov (United States)

2012-02-07

... INFORMATION CONTACT: If you have questions on this rule, call or email Ms. Judy Leung-Yee, Project Officer, First Coast Guard District, [email protected] , or telephone (212) 668-7165. If you have...

E3 Success Story -Reducing Rework With the Lean and Green Advantage: Metal Finishing Technologies, Inc

Science.gov (United States)

Green Suppliers Network representatives Judy Wlodarczyk and Bill Caplan, of CONNSTEP, Inc., trained the MFT review team, and together they completed current and future state value stream maps for the zinc plating line.

Generating Reliable and Affective Choreography through Engineering

DEFF Research Database (Denmark)

Jochum, Elizabeth

How do we define graceful motion? Is grace exclusively the province of living, sentient beings, or is it possible to automate graceful motion? The GRACE project (Generating Reliable and Affective Choreography through Engineering) uses these two questions to investigate what makes movement graceful....... The principal objective is to measure the role of kinesics on human-robot interactions through the development of an automated performance. If it is possible to create an automated program using autonomous, artificial agents that emulate aspects of human gracefulness, then we can apply this understanding more...... widely to contemporary robotics research and human-robot interaction (HRI)....

76 FR 35978 - Drawbridge Operation Regulations; Long Island, New York Inland Waterway From East Rockaway Inlet...

Science.gov (United States)

2011-06-21

... INFORMATION CONTACT: If you have questions on this rule, call or e-mail Mr. Judy Leung-Yee, Project Officer, First Coast Guard District, [email protected] , or telephone (212) 668-7165. If you have...

77 FR 46286 - Drawbridge Operation Regulations; Mystic River, Mystic, CT

Science.gov (United States)

2012-08-03

... INFORMATION CONTACT: If you have questions on this rule, call or email Ms. Judy K. Leung-Yee, Project Officer, First Coast Guard District, telephone (212) 668-7165, [email protected] . If you have questions...

Feeding Your Baby in the NICU

Science.gov (United States)

... at a healthy weight and avoiding alcohol and street drugs . Featured articles March of Dimes Premature Birth ... and Teresa Pitman (Prima Communications, 2000). The Womanly Art of Breastfeeding , by Gwen Gotsch and Judy Torgas ( ...

Suve suurim lustipidu / Laurence Lumiere

Index Scriptorium Estoniae

Lumiere, Laurence

2008-01-01

ABBA muusikale loodud muusikafilm "Mamma Mia!" : lavastaja Phyllida Lloyd : produtsent Judy Craymer : naispeaosas Meryl Streep : Suurbritannia - Ameerika Ühendriigid 2008. Filmi saamisloost. Lisatud nimekirjad "Maailma paremad muusikalid" ja "10 edukamat muusikali Põhja-Ameerika kinodes"

The Famous Women Dinner Service: In Conversation with Contemporary Art

Directory of Open Access Journals (Sweden)

Judy Chicago

2017-11-01

Full Text Available This conversation between Judy Chicago, The Women’s Art League, and Hana Leaper, filmed by Jonathan Law at the Elizabeth A. Sackler Center for Feminist Art, Brooklyn Museum, will be published in early 2018. The participants will discuss the Famous Women Dinner Service in relation to contemporary artworks, focusing on The Dinner Party (Judy Chicago, 1974–79 and Vagina China (The Women’s Art League, 2016–present. Questions explored will include: the role of hospitality and domesticity in feminist art projects; the evolution of iconography as it relates to aesthetic freedom and the visibility of women and their bodies; the strategies of shared authorship and collective practice; and what each of the artworks discussed offers their respective eras in terms of confronting taboos associated with women and their histories.

Functional and Structural Characterization of a Receptor-Like Kinase Involved in Germination and Cell Expansion in Arabidopsis

Science.gov (United States)

Wu, Zhen; Liang, Shan; Song, Wen; Lin, Guangzhong; Wang, Weiguang; Zhang, Heqiao; Han, Zhifu; Chai, Jijie

2017-01-01

Leucine-rich repeat receptor-like kinases (LRR-RLKs) are widespread in different plant species and play important roles in growth and development. Germination inhibition is vital for the completion of seed maturation and cell expansion is a fundamental cellular process driving plant growth. Here, we report genetic and structural characterizations of a functionally uncharacterized LRR-RLK, named GRACE (Germination Repression and Cell Expansion receptor-like kinase). Overexpression of GRACE in Arabidopsis exhibited delayed germination, enlarged cotyledons, rosette leaves and stubbier petioles. Conversely, these phenotypes were reversed in the T-DNA insertion knock-down mutant grace-1 plants. A crystal structure of the extracellular domain of GRACE (GRACE-LRR) determined at the resolution of 3.0 Å revealed that GRACE-LRR assumed a right-handed super-helical structure with an island domain (ID). Structural comparison showed that structure of the ID in GRACE-LRR is strikingly different from those observed in other LRR-RLKs. This structural observation implies that GRACE might perceive a new ligand for signaling. Collectively, our data support roles of GRACE in repressing seed germination and promoting cell expansion of Arabidopsis, presumably by perception of unknown ligand(s). PMID:29213277

Profil infectieux et mortalité des enfants âgés de 0 à 5 ans admis pour malnutrition aiguë sévère: étude de cohorte rétrospective au Centre Nutritionnel et Thérapeutique de Bukavu, République Démocratique du Congo

Science.gov (United States)

Kambale, Richard Mbusa; Kasengi, Joe Bwija; Kivukuto, John Mutendela; Cubaka, Liévin Murhula; Mungo, Bruno Masumbuko; Balaluka, Ghislain Bisimwa

2016-01-01

Introduction La malnutrition constitue une toile de fond sur laquelle se greffent plusieurs infections. L'objectif de ce travail est de déterminer les infections les plus létales, la durée médiane de séjour et le gain pondéral médian journalier des enfants malnutris. Méthodes Étude de cohorte rétrospective des enfants malnutris de 0 à 59 mois hospitalisés au Centre Nutritionnel et Thérapeutique de Bukavu du 1er janvier 2011 au 31 décembre 2013. L’évaluation du risque de survenue de décès par complication infectieuse a été faite par la mesure du risque relatif. Nous avons utilisé le test de Mann-Whitney pour comparer les médianes. Les Odd ratio ajustés par régression logistique et leurs intervalles de confiance à 95% du risque de mortalité ont été donnés pour chaque cause infectieuse. Résultats Au total, 574 enfants avaient été inclus. Cinq cent vingt et un (90.8%) enfants étaient sortis guéris, 10 (1.7%) avaient abandonné le traitement et 43 (7.5%) étaient décédés. La durée médiane de séjour était de 19 (13-26) jours et le gain pondéral médian journalier était de 7 (3-13) g/kg/j. Il existait une association statistiquement significative entre la mortalité et le sepsis / choc septique (p = 0,0004), la méningite (p = 0,00001), et l'infection à VIH (p = 0,02). Conclusion Une meilleure prise en charge de la malnutrition aigüe dans notre région devrait se baser sur la mise en place des unités spécialisées et bien équipées pour la prise en charge de la malnutrition associées aux infections sévères. PMID:27279964

When the grace period is over: Assessing the new Member States' compliance with EU requirements for oil stockholding

International Nuclear Information System (INIS)

Tosun, Jale

2011-01-01

The accumulation of appropriate emergency stocks of crude oil and petroleum products has been at the heart of the European Commission's efforts to increase the security of supply. This study investigates how effectively the 'new' Member States comply with the requirements of Council Directive 2006/67/EC, which imposes the obligation to maintain minimum stocks of crude oil and/or petroleum products. The empirical focus of this analysis is not only motivated by the practical relevance of this issue, but also by the fact that eleven of the twelve new Member States were given grace periods between one and seven years to bring their national stockholding arrangements in line with the European requirements. The granting of extended deadlines raises the question whether this instrument indeed facilitates the transposition process. The empirical findings show that except for Latvia, compliance with the EU stockholding requirements is generally very good. A more detailed analysis of the Latvian case highlights that the transposition delays principally stem from budgetary constraints. More generally, the individual new Member States' capacity to cope with the financial burdens and the degree of adjustment pressure determine the variation in oil stock levels. - Highlights: → Compliance with Council Directive 2006/67/EC is generally very good in the new Member States. → Solely Latvia faces difficulties in developing adequate oil stock levels. → Latvia's insufficient compliance can be attributed to severe budgetary constraints. → Financial capacity and adjustment pressure determine cross-country variation in stock levels.

76 FR 44091 - Veterans' Rural Health Advisory Committee; Notice of Meeting

Science.gov (United States)

2011-07-22

... Rural Health, 1722 I Street, NW., Washington, DC. The toll- free number for the meeting is 1-800-767... contact Judy Bowie, Designated Federal Officer, at rural.health.inquiry@va.gov or (202) 461-7100. Dated...

NIH Research Leads to Cervical Cancer Vaccine

Science.gov (United States)

... Issues Sexually Transmitted Diseases NIH Research Leads to Cervical Cancer Vaccine Past Issues / Fall 2008 Table of Contents ... in women, the cause of the majority of cervical cancers. Photo courtesy of Judy Folkenberg, NLM Writer By ...

Kahe kuninganna duell / Timo Diener

Index Scriptorium Estoniae

Diener, Timo

2007-01-01

Mängufilm "Ühe skandaali märkmed" ("Notes on a Scandal") : stsenarist Zoe Helleri romaani järgi Patrick Marber : režissöör Richard Eyre : peaosades Judi Dench, Cate Blanchett : Suurbritannia 2006

"Ühe skandaali märkmed" : kui kiindumusest tõuseb tüli / Andris Feldmanis

Index Scriptorium Estoniae

Feldmanis, Andris, 1982-

2007-01-01

Mängufilm "Ühe skandaali märkmed" ("Notes on a Scandal") : stsenarist Zoe Helleri romaani järgi Patrick Marber : režissöör Richard Eyre : peaosades Judi Dench, Cate Blanchett : Suurbritannia 2006

Characteristics of official and experimental GRACE time series by GFZ and CSR - with applications to polar signals

Science.gov (United States)

Horvath, Alexander; Horwath, Martin; Pail, Roland

2014-05-01

The Release-05 monthly solutions by the three centers of the GRACE Science and Data System are a significant improvement with respect to the previous Release 4. Meanwhile, previous assessments have revealed different noise levels between the solutions by CSR, GFZ and JPL, and also different amplitudes of interannual signal in the solutions by GFZ as compared to the two other centers. Encouraged by the science community, GFZ and CSR have kindly provided additional sets of time series. GFZ has reprocessed the RL05 monthly solutions (up to degree and order 90) with revised processing. CSR has made available monthly solutions with standard processing up to degree and order 96, in addition to their solutions up to degree and order 60. We compare these different time series with respect to their signal and noise content and analyze them on global and regional scale. For the regional scale our special interest is paid on Antarctica and on revealing polar signals such as ice mass trends and GIA. Following the necessity of destriping, an optimal choice for the setup of the Swenson & Wahr filter approach is evaluated to adapt to the specific signal and noise level in Antarctica. Furthermore we analyze the potential benefit of mixed time series solutions in order to combine the strengths of the solutions available. Concerning the question for an optimal maximum degree we suggest that for resolving large polar ice mass changes, it would be beneficial to provide gravity field variations even beyond degree 90.

Sensed fittingness between act and consequence: The last acts of Esther in the book of Esther and Grace in the film Dogville

Directory of Open Access Journals (Sweden)

Gerrie Snyman

2013-08-01

Full Text Available The book of Esther employs a wisdom theme to develop the plot and its denouement. The particular illustration of wisdom is that of role reversal. Haman, the second in command, gets kicked out and the leaders of those he sought to lock out filled his position. However, the role reversal becomes more than a mere change in status. As Grace needed to step into her gangster father’s shoes in the film Dogville in order to achieve justice, so Esther had to step into Persian shoes to achieve justice. The execution of justice is an untidy and messy affair. The question this article puts on the table is whether Esther acts with justice in her quest for retribution. In answering this question, the article firstly inquires into the narrative rationality of the story and the denouement of the plot. Related to the book of Esther’s narrative rationality, the article examines the question of wisdom from a narrator’s and character’s perspective. Lastly, it will then put the issue of justice on the table with the help of the film Dogville in order to see whether there is a link between wisdom and justice.

Terrestrial Water Storage in African Hydrological Regimes Derived from GRACE Mission Data: Intercomparison of Spherical Harmonics, Mass Concentration, and Scalar Slepian Methods.

Science.gov (United States)

Rateb, Ashraf; Kuo, Chung-Yen; Imani, Moslem; Tseng, Kuo-Hsin; Lan, Wen-Hau; Ching, Kuo-En; Tseng, Tzu-Pang

2017-03-10

Spherical harmonics (SH) and mascon solutions are the two most common types of solutions for Gravity Recovery and Climate Experiment (GRACE) mass flux observations. However, SH signals are degraded by measurement and leakage errors. Mascon solutions (the Jet Propulsion Laboratory (JPL) release, herein) exhibit weakened signals at submascon resolutions. Both solutions require a scale factor examined by the CLM4.0 model to obtain the actual water storage signal. The Slepian localization method can avoid the SH leakage errors when applied to the basin scale. In this study, we estimate SH errors and scale factors for African hydrological regimes. Then, terrestrial water storage (TWS) in Africa is determined based on Slepian localization and compared with JPL-mascon and SH solutions. The three TWS estimates show good agreement for the TWS of large-sized and humid regimes but present discrepancies for the TWS of medium and small-sized regimes. Slepian localization is an effective method for deriving the TWS of arid zones. The TWS behavior in African regimes and its spatiotemporal variations are then examined. The negative TWS trends in the lower Nile and Sahara at -1.08 and -6.92 Gt/year, respectively, are higher than those previously reported.

Metodologia da manutenção centrada em confiabilidade aplicada a pára-raios de alta tensão

OpenAIRE

Britto, Tales Marques de

2006-01-01

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia Elétrica Este trabalho de dissertação apresenta a aplicação da metodologia da Manutenção Centrada em Confiabilidade (MCC) em pára-raios de alta tensão, como forma de apoio à tomada de decisão em um sistema de Análise e Diagnóstico de Equipamentos de Subestações de Transmissão de Energia (DianE). Este trabalho aborda o equipamento pára-raios descrevendo suas caracterí...

From Out of Our Voices

Directory of Open Access Journals (Sweden)

Evangelia Papanikolaou

2010-01-01

Full Text Available Note from the interviewer: Diane Austin's new book “The Theory and Practice of Vocal Psychotherapy: Songs of the Self” (2008 which was published recently, has been an excellent opportunity to learn more about the use of voice in therapy, its clinical applications and its enormous possibilities that offers within a psychotherapeutic setting. This interview focuses on introducing some of these aspects based on Austin’s work, and on exploring her background, motivations and considerations towards this pioneer music-therapeutic approach. The interview has been edited by Diane Austin and Evangelia Papanikolaou and took place via a series of emails, dated from September to December 2009.

Ecological Effects of Channelization on a Tropical Marine Ecosystem

African Journals Online (AJOL)

USER

important factor limiting usable fish habitat in such systems (Judy et al., 1984; Sheridan et al., 2002). ... affects fish nutrition and reproduction is critical, because the primary effects of ..... To measure the environmental effect of the sedimentation.

77 FR 3327 - Veterans' Rural Health Advisory Committee; Notice of Meeting

Science.gov (United States)

2012-01-23

..., 1722 I Street NW., Washington, DC. The toll-free number for the meeting is 1 (800) 767-1750, and the... information should contact Judy Bowie, Designated Federal Officer, at rural.health.inquiry@va.gov or (202) 461...

Madalmaade nukunäitlejate paremik hiilgas Tallinn Treffil / Tiiu Laks

Index Scriptorium Estoniae

Laks, Tiiu, 1984-

2010-01-01

5.-8. juunini 2010 toimuvast rahvusvahelisest festivalist Tallinn Treff. Hollandi trupi DudaPaiva lavastusest "Needus". Nukunäitleja Neville Tranteri (Austraalia-Holland) lavastusest "Punch ja Judy Afganistanis". Stef Vettersi (Belgia) etendusest "Tema kõrgeausus Ottfriedi tundmatu maailm"

Genetics Home Reference: trisomy 13

Science.gov (United States)

... 15;93(6):801-3. Citation on PubMed Hall HE, Chan ER, Collins A, Judis L, Shirley S, ... CRISPR-Cas9? What is direct-to-consumer genetic testing? What is precision medicine? What is newborn screening? ...

Understanding linkages between global climate indices and terrestrial water storage changes over Africa using GRACE products.

Science.gov (United States)

Anyah, R O; Forootan, E; Awange, J L; Khaki, M

2018-09-01

Africa, a continent endowed with huge water resources that sustain its agricultural activities is increasingly coming under threat from impacts of climate extremes (droughts and floods), which puts the very precious water resource into jeopardy. Understanding the relationship between climate variability and water storage over the continent, therefore, is paramount in order to inform future water management strategies. This study employs Gravity Recovery And Climate Experiment (GRACE) satellite data and the higher order (fourth order cumulant) statistical independent component analysis (ICA) method to study the relationship between terrestrial water storage (TWS) changes and five global climate-teleconnection indices; El Niño-Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), Madden-Julian Oscillation (MJO), Quasi-Biennial Oscillation (QBO) and the Indian Ocean Dipole (IOD) over Africa for the period 2003-2014. Pearson correlation analysis is applied to extract the connections between these climate indices (CIs) and TWS, from which some known strong CI-rainfall relationships (e.g., over equatorial eastern Africa) are found. Results indicate unique linear-relationships and regions that exhibit strong linkages between CIs and TWS. Moreover, unique regions having strong CI-TWS connections that are completely different from the typical ENSO-rainfall connections over eastern and southern Africa are also identified. Furthermore, the results indicate that the first dominant independent components (IC) of the CIs are linked to NAO, and are characterized by significant reductions of TWS over southern Africa. The second dominant ICs are associated with IOD and are characterized by significant increases in TWS over equatorial eastern Africa, while the combined ENSO and MJO are apparently linked to the third ICs, which are also associated with significant increase in TWS changes over both southern Africa, as well as equatorial eastern Africa. Copyright © 2018

So You Want Your Child To Learn French! Second Revised Edition.

Science.gov (United States)

Fleming, Berkeley, Ed.; Whitla, Margaret, Ed.

This collection of essays on early French second language instruction includes: "Why Bilingualism?" (Steven MacKinnon); "French Second-Language Programs: Alternative Approaches" (Henry P. Edwards); "Core French: A Brighter Future" (Janet Poyen, Judy Gibson); "The Parents' Role" (Deborah Whale); "Franco…

Indigenous edible plants as sources of nutrients and health benefitting components (nutraceuticals)

CSIR Research Space (South Africa)

Dlamini, N

2010-08-31

Full Text Available Africa, not only to address health problems and malnutrition, but also to create employment through establishment of industries © CSIR 2010 Slide 21 The Team at CSIR Tshidi Moroka Nomusa Dlamini Gerda Botha Judy Reddy Lauraine Mlotshwa Middah...

Keeping Seniors Safe (A Cup of Health with CDC)

Centers for Disease Control (CDC) Podcasts

Falls are the leading cause of injuries among older adults in the U.S. and can result in reduced mobility and loss of independence. In this podcast, Dr. Judy Stevens discusses ways to prevent fall-related injuries among older adults.

New insights on intraplate volcanism in French Polynesia from wavelet analysis of GRACE, CHAMP, and sea surface data

Science.gov (United States)

Panet, I.; Chambodut, A.; Diament, M.; Holschneider, M.; Jamet, O.

2006-09-01

In this paper, we discuss the origin of superswell volcanism on the basis of representation and analysis of recent gravity and magnetic satellite data with wavelets in spherical geometry. We computed a refined gravity field in the south central Pacific based on the GRACE satellite GGM02S global gravity field and the KMS02 altimetric grid, and a magnetic anomaly field based on CHAMP data. The magnetic anomalies are marked by the magnetic lineation of the seafloor spreading and by a strong anomaly in the Tuamotu region, which we interpret as evidence for crustal thickening. We interpret our gravity field through a continuous wavelet analysis that allows to get a first idea of the internal density distribution. We also compute the continuous wavelet analysis of the bathymetric contribution to discriminate between deep and superficial sources. According to the gravity signature of the different chains as revealed by our analysis, various processes are at the origin of the volcanism in French Polynesia. As evidence, we show a large-scale anomaly over the Society Islands that we interpret as the gravity signature of a deeply anchored mantle plume. The gravity signature of the Cook-Austral chain indicates a complex origin which may involve deep processes. Finally, we discuss the particular location of the Marquesas chain as suggesting that the origin of the volcanism may interfere with secondary convection rolls or may be controlled by lithospheric weakness due to the regional stress field, or else related to the presence of the nearby Tuamotu plateau.