Science.gov

Sample records for mass balances examining

  1. Greenland Ice Sheet Mass Balance

    NASA Technical Reports Server (NTRS)

    Reeh, N.

    1984-01-01

    Mass balance equation for glaciers; areal distribution and ice volumes; estimates of actual mass balance; loss by calving of icebergs; hydrological budget for Greenland; and temporal variations of Greenland mass balance are examined.

  2. Meta-Analysis of Mass Balances Examining Chemical Fate during Wastewater Treatment

    PubMed Central

    2008-01-01

    Mass balances are an instructive means for investigating the fate of chemicals during wastewater treatment. In addition to the aqueous-phase removal efficiency (Φ), they can inform on chemical partitioning, transformation, and persistence, as well as on the chemical loading to streams and soils receiving, respectively, treated effluent and digested sewage sludge (biosolids). Release rates computed on a per-capita basis can serve to extrapolate findings to a larger scale. This review examines over a dozen mass balances conducted for various organic wastewater contaminants, including prescription drugs, estrogens, fragrances, antimicrobials, and surfactants of differing sorption potential (hydrophobicity), here expressed as the 1-octanol−water partition coefficient (KOW) and the organic carbon normalized sorption coefficient (KOC). Major challenges to mass balances are the collection of representative samples and accurate quantification of chemicals in sludge. A meta-analysis of peer-reviewed data identified sorption potential as the principal determinant governing chemical persistence in biosolids. Occurrence data for organic wastewater compounds detected in digested sludge followed a simple nonlinear model that required only KOW or KOC as the input and yielded a correlation coefficient of 0.9 in both instances. The model predicted persistence in biosolids for the majority (>50%) of the input load of organic wastewater compounds featuring a log10KOW value of greater than 5.2 (log10KOC > 4.4). In contrast, hydrophobicity had no or only limited value for estimating, respectively, Φ and the overall persistence of a chemical during conventional wastewater treatment. PMID:18800497

  3. Catchment conceptualisation for examining applicability of chloride mass balance method in an area of historical forest clearance

    NASA Astrophysics Data System (ADS)

    Guan, H.; Love, A.; Simmons, C. T.; Ding, Z.; Hutson, J.

    2009-11-01

    Among various approaches for estimating groundwater recharge, chloride mass balance (CMB) method is one of the most frequently used, in particular, for arid and semiarid regions. Widespread native vegetation clearance, common history in many areas globally, has changed land surface boundary condition, posing a question whether the current system has reached new chloride equilibrium for CMB application. To examine CMB applicability for catchments, conceptual catchment types of various chloride equilibrium conditions are defined. The conceptualization, combined with some local climate conditions, is demonstrated to be useful in examining whether a catchment has reached new chloride equilibrium. The six conceptual catchment types are tested with eleven selected catchments in the Mount Lofty Ranges (MLR), a coastal hilly area in South Australia having experienced historical widespread forest clearance. The results show that six of the eleven catchments match type VI chloride balance condition (chloride non-equilibrium with a gaining stream), with the ratio of stream chloride output over atmospheric chloride input (catchment chloride O/I) ranging from 2 to 4. Two catchments match type V chloride balance condition (chloride non-equilibrium with a losing stream), with catchment chloride O/I values about 0.5. For these catchments, the CMB method is not appropriate to apply. The results also suggest that neither a below-one chloride O/I value nor a low seasonal fluctuation of streamflow chloride concentration (a factor below 4) guarantees a chloride equilibrium condition in the study area. But a large chloride O/I value (above one) and a large fluctuation of streamflow chloride concentration (a factor of 10 and above) generally indicates either a chloride disequilibrium, or cross-catchment water transfer, or both, for which CMB is not applicable. Based on the regression between chloride O/I values and annual precipitation for type VI catchments, a catchment with annual

  4. Catchment conceptualisation for examining applicability of chloride mass balance method in an area with historical forest clearance

    NASA Astrophysics Data System (ADS)

    Guan, H.; Love, A. J.; Simmons, C. T.; Hutson, J.; Ding, Z.

    2010-07-01

    Of the various approaches for estimating groundwater recharge, the chloride mass balance (CMB) method is one of the most frequently used, especially for arid and semiarid regions. Widespread native vegetation clearance, common in many areas globally, has changed the land surface boundary condition, posing the question as to whether the current system has reached new chloride equilibrium, required for a CMB application. Although a one-dimensional CMB can be applied at a point where the water and chloride fluxes are locally in steady state, the CMB method is usually applied at a catchment scale owing to significant lateral flows in mountains. The applicability of the CMB method to several conceptual catchment types of various chloride equilibrium conditions is examined. The conceptualisation, combined with some local climate conditions, is shown to be useful in assessing whether or not a catchment has reached new chloride equilibrium. The six conceptual catchment types are tested with eleven selected catchments in the Mount Lofty Ranges (MLR), a coastal hilly area in South Australia having experienced widespread historical forest clearance. The results show that six of the eleven catchments match a type VI chloride balance condition (chloride non-equilibrium with a gaining stream), with the ratios of stream chloride output (O) over atmospheric chloride input (I), or catchment chloride O/I ratios, ranging from 2 to 4. Two catchments match a type V chloride balance condition (chloride non-equilibrium with a losing stream), with catchment chloride O/I ratios about 0.5. For these type V and type VI catchments, the CMB method is not applicable. The results also suggest that neither a chloride O/I ratio less than one nor a low seasonal fluctuation of streamflow chloride concentration (a factor below 4) guarantees a chloride equilibrium condition in the study area. A large chloride O/I value (above one) and a large fluctuation of streamflow chloride concentration (a factor

  5. Micromechanical Oscillating Mass Balance

    NASA Technical Reports Server (NTRS)

    Altemir, David A. (Inventor)

    1997-01-01

    A micromechanical oscillating mass balance and method adapted for measuring minute quantities of material deposited at a selected location, such as during a vapor deposition process. The invention comprises a vibratory composite beam which includes a dielectric layer sandwiched between two conductive layers. The beam is positioned in a magnetic field. An alternating current passes through one conductive layers, the beam oscillates, inducing an output current in the second conductive layer, which is analyzed to determine the resonant frequency of the beam. As material is deposited on the beam, the mass of the beam increases and the resonant frequency of the beam shifts, and the mass added is determined.

  6. Improving Mass Balance Modeling of Benchmark Glaciers

    NASA Astrophysics Data System (ADS)

    van Beusekom, A. E.; March, R. S.; O'Neel, S.

    2009-12-01

    The USGS monitors long-term glacier mass balance at three benchmark glaciers in different climate regimes. The coastal and continental glaciers are represented by Wolverine and Gulkana Glaciers in Alaska, respectively. Field measurements began in 1966 and continue. We have reanalyzed the published balance time series with more modern methods and recomputed reference surface and conventional balances. Addition of the most recent data shows a continuing trend of mass loss. We compare the updated balances to the previously accepted balances and discuss differences. Not all balance quantities can be determined from the field measurements. For surface processes, we model missing information with an improved degree-day model. Degree-day models predict ablation from the sum of daily mean temperatures and an empirical degree-day factor. We modernize the traditional degree-day model as well as derive new degree-day factors in an effort to closer match the balance time series and thus better predict the future state of the benchmark glaciers. For subsurface processes, we model the refreezing of meltwater for internal accumulation. We examine the sensitivity of the balance time series to the subsurface process of internal accumulation, with the goal of determining the best way to include internal accumulation into balance estimates.

  7. Mass balance assessment using GPS

    NASA Technical Reports Server (NTRS)

    Hulbe, Christina L.

    1993-01-01

    Mass balance is an integral part of any comprehensive glaciological investigation. Unfortunately, it is hard to determine at remote locations where there is no fixed reference. The Global Positioning System (GPS) offers a solution. Simultaneous GPS observations at a known location and the remote field site, processed differentially, will accurately position the camp site. From there, a monument planted in the firn atop the ice can also be accurately positioned. Change in the monument's vertical position is a direct indicator of ice thickness change. Because the monument is not connected to the ice, its motion is due to both mass balance change and to the settling of firn as it densifies into ice. Observations of relative position change between the monument and anchors at various depths within the firn are used to remove the settling effect. An experiment to test this method has begun at Byrd Station on the West Antarctic Ice Sheet and the first epoch of observations was made. Analysis indicates that positioning errors will be very small. It appears likely that the largest errors involved with this technique will arise from ancillary data needed to determine firn settling.

  8. Examining Fund Balance in Michigan School Districts

    ERIC Educational Resources Information Center

    Bidin, Zainin

    2012-01-01

    This research examines the financial profiles of 550 public school districts in Michigan and highlights the association between school district fund balance and the following eleven indicators: enrollment, percent enrollment change, percent of students receive free and reduced lunch (FRL), percent of special education students, percent of English…

  9. 14 CFR 27.659 - Mass balance.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Mass balance. 27.659 Section 27.659... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction Rotors § 27.659 Mass balance. (a) The rotors... flutter at any speed up to the maximum forward speed. (b) The structural integrity of the mass...

  10. 14 CFR 27.659 - Mass balance.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Mass balance. 27.659 Section 27.659... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction Rotors § 27.659 Mass balance. (a) The rotors... flutter at any speed up to the maximum forward speed. (b) The structural integrity of the mass...

  11. 14 CFR 23.659 - Mass balance.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Mass balance. 23.659 Section 23.659 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... Surfaces § 23.659 Mass balance. The supporting structure and the attachment of concentrated mass...

  12. 14 CFR 23.659 - Mass balance.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Mass balance. 23.659 Section 23.659 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... Surfaces § 23.659 Mass balance. The supporting structure and the attachment of concentrated mass...

  13. 14 CFR 29.659 - Mass balance.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Mass balance. 29.659 Section 29.659... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction Rotors § 29.659 Mass balance. (a) The rotor... flutter at any speed up to the maximum forward speed. (b) The structural integrity of the mass...

  14. 14 CFR 29.659 - Mass balance.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Mass balance. 29.659 Section 29.659... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction Rotors § 29.659 Mass balance. (a) The rotor... flutter at any speed up to the maximum forward speed. (b) The structural integrity of the mass...

  15. 14 CFR 29.659 - Mass balance.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Mass balance. 29.659 Section 29.659... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction Rotors § 29.659 Mass balance. (a) The rotor... flutter at any speed up to the maximum forward speed. (b) The structural integrity of the mass...

  16. 14 CFR 23.659 - Mass balance.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Mass balance. 23.659 Section 23.659 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... Surfaces § 23.659 Mass balance. The supporting structure and the attachment of concentrated mass...

  17. 14 CFR 27.659 - Mass balance.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Mass balance. 27.659 Section 27.659... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction Rotors § 27.659 Mass balance. (a) The rotors... flutter at any speed up to the maximum forward speed. (b) The structural integrity of the mass...

  18. 14 CFR 23.659 - Mass balance.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Mass balance. 23.659 Section 23.659 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... Surfaces § 23.659 Mass balance. The supporting structure and the attachment of concentrated mass...

  19. 14 CFR 23.659 - Mass balance.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Mass balance. 23.659 Section 23.659 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... Surfaces § 23.659 Mass balance. The supporting structure and the attachment of concentrated mass...

  20. 14 CFR 29.659 - Mass balance.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Mass balance. 29.659 Section 29.659... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction Rotors § 29.659 Mass balance. (a) The rotor... flutter at any speed up to the maximum forward speed. (b) The structural integrity of the mass...

  1. 14 CFR 27.659 - Mass balance.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Mass balance. 27.659 Section 27.659... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction Rotors § 27.659 Mass balance. (a) The rotors... flutter at any speed up to the maximum forward speed. (b) The structural integrity of the mass...

  2. 14 CFR 29.659 - Mass balance.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Mass balance. 29.659 Section 29.659... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction Rotors § 29.659 Mass balance. (a) The rotor... flutter at any speed up to the maximum forward speed. (b) The structural integrity of the mass...

  3. 14 CFR 27.659 - Mass balance.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Mass balance. 27.659 Section 27.659... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction Rotors § 27.659 Mass balance. (a) The rotors... flutter at any speed up to the maximum forward speed. (b) The structural integrity of the mass...

  4. Mass balancing of hollow fan blades

    NASA Technical Reports Server (NTRS)

    Kielb, R. E.

    1986-01-01

    A typical section model is used to analytically investigate the effect of mass balancing as applied to hollow, supersonic fan blades. A procedure to determine the best configuration of an internal balancing mass to provide flutter alleviation is developed. This procedure is applied to a typical supersonic shroudless fan blade which is unstable in both the solid configuration and when it is hollow with no balancing mass. The addition of an optimized balancing mass is shown to stabilize the blade at the design condition.

  5. Surface melt dominates Alaska glacier mass balance

    USGS Publications Warehouse

    Larsen Chris F; Burgess, E; Arendt, A.A.; O'Neel, Shad; Johnson, A.J.; Kienholz, C.

    2015-01-01

    Mountain glaciers comprise a small and widely distributed fraction of the world's terrestrial ice, yet their rapid losses presently drive a large percentage of the cryosphere's contribution to sea level rise. Regional mass balance assessments are challenging over large glacier populations due to remote and rugged geography, variable response of individual glaciers to climate change, and episodic calving losses from tidewater glaciers. In Alaska, we use airborne altimetry from 116 glaciers to estimate a regional mass balance of −75 ± 11 Gt yr−1 (1994–2013). Our glacier sample is spatially well distributed, yet pervasive variability in mass balances obscures geospatial and climatic relationships. However, for the first time, these data allow the partitioning of regional mass balance by glacier type. We find that tidewater glaciers are losing mass at substantially slower rates than other glaciers in Alaska and collectively contribute to only 6% of the regional mass loss.

  6. Miniature Piezoelectric Macro-Mass Balance

    NASA Technical Reports Server (NTRS)

    Sherrit, Stewart; Trebi-Ollennu, Ashitey; Bonitz, Robert G.; Bar-Cohen, Yoseph

    2010-01-01

    Mass balances usually use a strain gauge that requires an impedance measurement and is susceptible to noise and thermal drift. A piezoelectric balance can be used to measure mass directly by monitoring the voltage developed across the piezoelectric balance, which is linear with weight or it can be used in resonance to produce a frequency change proportional to the mass change (see figure). The piezoelectric actuator/balance is swept in frequency through its fundamental resonance. If a small mass is added to the balance, the resonance frequency shifts down in proportion to the mass. By monitoring the frequency shift, the mass can be determined. This design allows for two independent measurements of mass. Additionally, more than one sample can be verified because this invention allows for each sample to be transported away from the measuring device upon completion of the measurement, if required. A piezoelectric actuator, or many piezoelectric actuators, was placed between the collection plate of the sampling system and the support structure. As the sample mass is added to the plate, the piezoelectrics are stressed, causing them to produce a voltage that is proportional to the mass and acceleration. In addition, a change in mass delta m produces a change in the resonance frequency with delta f proportional to delta m. In a microgravity environment, the spacecraft could be accelerated to produce a force on the piezoelectric actuator that would produce a voltage proportional to the mass and acceleration. Alternatively, the acceleration could be used to force the mass on the plate, and the inertial effects of the mass on the plate would produce a shift in the resonance frequency with the change in frequency related to the mass change. Three prototypes of the mass balance mechanism were developed. These macro-mass balances each consist of a solid base and an APA 60 Cedrat flextensional piezoelectric actuator supporting a measuring plate. A similar structure with 3 APA

  7. Assessing streamflow sensitivity to variations in glacier mass balance

    NASA Astrophysics Data System (ADS)

    Oneel, S.; Hood, E. W.; Arendt, A. A.; Sass, L. C.; March, R. S.

    2013-12-01

    We examine long-term streamflow and mass balance data from two Alaskan glaciers located in climatically distinct basins: Gulkana Glacier, a continental glacier located in the Alaska Range, and Wolverine Glacier, a maritime glacier located in the Kenai Mountains. Both glaciers lost mass, primarily as a result of summer warming, and both basins exhibit increasing streamflow over the 1966-2011 study interval. We estimated total glacier runoff via summer mass balance, and separated the fraction related to annual mass imbalances. In both climates, the fraction of streamflow related to annual mass balance averages less than 20%, substantially smaller than the fraction related to total summer mass loss (>50%), which occurs even in years of glacier growth. The streamflow fraction related to changes in annual mass balance has increased only in the continental environment. In the maritime climate, where deep winter snowpacks and frequent rain events drive consistently high runoff, the magnitude of this streamflow fraction is small and highly variable, precluding detection of any existing trend. Changes in streamflow related to annual balance are often masked by interannual variability of maritime glacier mass balance, such that predicted scenarios of continued glacier recession are more likely to impact the quality and timing of runoff than the total basin water yield.

  8. LAKE MICHIGAN MASS BALANCE ATRAZINE DATA

    EPA Science Inventory

    The Lake Michigan Mass Balance Study measured PCBs, mercury, trans-nonachlor, and atrazine in rivers, the atmosphere, sediments, lake water, and the food chain. A mathematical model will predict what effect reducing pollution will have on the lake, and its large fish (lake trout ...

  9. LAKE MICHIGAN MASS BALANCE: MODELING PROCESS

    EPA Science Inventory

    The Lake Michigan Mass Balance Study measured PCBs, mercury, trans-nonachlor, and atrazine in rivers, the atmosphere, sediments, lake water, and the food chain. A mathematical model will predict what effect reducing pollution will have on the lake, and its large fish (lake trout ...

  10. LAKE MICHIGAN MASS BALANCE PCB DATA

    EPA Science Inventory

    The Lake Michigan Mass Balance Study measured PCBs, mercury, trans-nonachlor, and atrazine in rivers, the atmosphere, sediments, lake water, and the food chain. A mathematical model will predict what effect reducing pollution will have on the lake, and its large fish (lake trout ...

  11. Automated balance for determining true mass

    SciTech Connect

    Meyer, J.E.

    1982-08-08

    An automated weighing system utilizing a precision electronic balance and a small desktop computer is described. An example of a computer program demonstrating some of the capabilities attainable with this system is included. The program demonstrates a substitution weighing technique with true mass determination for the object being weighed.

  12. When Equal Masses Don't Balance

    ERIC Educational Resources Information Center

    Newburgh, Ronald; Peidle, Joseph; Rueckner, Wolfgang

    2004-01-01

    We treat a modified Atwood's machine in which equal masses do not balance because of being in an accelerated frame of reference. Analysis of the problem illuminates the meaning of inertial forces, d'Alembert's principle, the use of free-body diagrams and the selection of appropriate systems for the diagrams. In spite of the range of these…

  13. MBA, mass balance area user guide

    SciTech Connect

    Russell, V.K.

    1994-09-22

    This document presents the Mass BAlance (MBA) database system user instructions which explain how to record the encapsulation activity from the K Basin as it is being performed on the computer, activity associated with keeping the work area safe from going critical, and administrative functions associated with the system. This document includes the user instructions, which also serve as the software requirements specification for the system implemented on the microcomputer. This includes suggested user keystrokes, examples of screens displayed by the system, and reports generated by the system. It shows how the system is organized, via menus and screens. It does not explain system design nor provide programmer instructions. MBA was written to equip the personnel performing K-Basin encapsulation tasks with a conservative estimate of accumulated mass during the processing of canisters into and out of the chute, primarily in the K-East basin.

  14. Greenland ice sheet mass balance: a review.

    PubMed

    Khan, Shfaqat A; Aschwanden, Andy; Bjørk, Anders A; Wahr, John; Kjeldsen, Kristian K; Kjær, Kurt H

    2015-04-01

    Over the past quarter of a century the Arctic has warmed more than any other region on Earth, causing a profound impact on the Greenland ice sheet (GrIS) and its contribution to the rise in global sea level. The loss of ice can be partitioned into processes related to surface mass balance and to ice discharge, which are forced by internal or external (atmospheric/oceanic/basal) fluctuations. Regardless of the measurement method, observations over the last two decades show an increase in ice loss rate, associated with speeding up of glaciers and enhanced melting. However, both ice discharge and melt-induced mass losses exhibit rapid short-term fluctuations that, when extrapolated into the future, could yield erroneous long-term trends. In this paper we review the GrIS mass loss over more than a century by combining satellite altimetry, airborne altimetry, interferometry, aerial photographs and gravimetry data sets together with modelling studies. We revisit the mass loss of different sectors and show that they manifest quite different sensitivities to atmospheric and oceanic forcing. In addition, we discuss recent progress in constructing coupled ice-ocean-atmosphere models required to project realistic future sea-level changes. PMID:25811969

  15. Mass balance study of gravitational mass movements in proglacial systems

    NASA Astrophysics Data System (ADS)

    Rohn, Joachim; Vehling, Lucas; Moser, Michael

    2013-04-01

    In the framework of the DFG joint research project PROSA (high resoluted measurements of morphodynamics in rapidly changing PROglacial Systems of the Alps), mass movements are investigated geotechnically and process rates will be determined. As result, the actual mass balance for gravitational mass movements will be investigated exemplarily in an alpine glacier foreland in this PROSA sub-project. Alpine glacier forelands are defined as the area between the edge of the glacier and the moraines of the latest maximum in 1850. Since then, the region has become ice free due to the retreat of the glaciers. Because of this recent development, the glacier foreland differs considerably from the surrounding landscape and exhibits a rapid morphodynamic development. Mass movements like landslides and rock falls contribute a remarkable portion to total sediment transport in this area. As study area the region between Gepatschferner and Gepatsch backwater was choosen. The study area encompasses 62,5 km², lies at altitudes between 1759 and 3539 m a.s.l. and around 30 % are covered by glacier. Basic prerequisite is the geotechnical inventory-taking including the production of a geotechnical map. All mass balance studies for gravitational mass movements will base on this data collection. Short term behaviour during extreme meteorological events will be investigated as well, as the long term behaviour of the alpine slopes. The results of repeated high-resolution airborne laser scanning will contribute to a complete area-wide detection of surface changes. Detailed periodical terrestrial laser scanning of steep rock walls and their scree cones, as well as of slopes with soft rock will complete the data set. Spot tests with nets collecting the rock fall material, constructed on elected scree cones, allow the control and verification of the collected data. Mass movements in hard rock apart from rock fall processes, like rock creep, rock sliding and sagging will be monitored

  16. Balancing The Books - A Statistical Theory of Mass Balances

    NASA Astrophysics Data System (ADS)

    O'Kane, J. P.

    Mass budgets, without a theory, are an empirical "method of choice" in the environ- mental sciences. There is however a difficulty. Budgets are usually presented as perfect balances with no closing error, justified by the law of mass conservation. Neverthe- less, there is always a closing error! Declaring the error, e, simply raises the question of the acceptability of the budget. To answer this we need a reference quantity against which to compare e. This quantity can only be provided by theory and must also be a mathematical function of all the budget data. Two statistical techniques provide the theory and the function: (1) Probability sampling for estimating the terms of the bud- get, the closing error and their sampling precision, and (2) Hypothesis testing that any particular value of e is due to chance alone. Both techniques must satisfy R.A. Fisher's "vital requirement that the actual and physical conduct of experiments should govern the statistical procedure of their interpretation". Probability sampling is any sampling procedure governed by sets of random numbers. Applying the calculus of probability to the chosen procedure, delivers the theoretical probability distribution of the terms of the budget, and the closing error e', on the assumption that there are no systematic errors of measurement or missing fluxes. In the simplest case, we may use simple or stratified random sampling, defined on a spatio- temporal sampling frame, which covers the duration of the budget on the space-filling object. When the number of independent measurements (samples) is statistically large, the central limit theorem implies that e' is normally distributed. The assumption that there are no systematic errors of measurement, sampling bias, or missing fluxes, and the law of mass conservation, together imply that E(e') = 0. Unbiased, independent sampling of the terms of the budget makes the variance Var(e') equal to the sum of the sampling variances of the individual terms in the

  17. Sedimentation rate determination by radionuclides mass balances

    NASA Astrophysics Data System (ADS)

    Cazala, C.; Reyss, J. L.; Decossas, J. L.; Royer, A.

    2003-04-01

    In the past, uranium mining activity took place in the area around Limoges, France. Even nowadays, this activity results in an increase in the input and availability of radionuclides in aquifer reservoirs, making of this area a suitable site to better understand the behaviour of radionuclides in the surficial environment. Water was sampled monthly over the entire year 2001 in a brook that collects mine water and in a lake fed by this brook. Samples were filtered through 0.45μm filters to remove particles. Activities of 238U, 226Ra, 210Pb, 228Th and 228Ra were measured on particulate (>0.45μm), dissolved (<0.45μm) and total (unfiltered) fractions by gamma spectrometry in the well of a high efficiency, low background, germanium detector settled in an underground laboratory, protected from cosmic rays by 1700 m of rocks (LSM, CNRS-CEA, French Alps). Activities measured in particulate and dissolved fractions were summed and compared to the one measured in unfiltered water to test the filtration yield. No significant loss or contamination were detected. In the brook water, 70% of 238U, 60% of 226Ra and 80% of 210Pb are associated with particles. Activities associated with particles decrease drastically along with the velocity of current when the stream enters the lake. An annual mass balance of radionuclides carried by particles from the stream to the lake was used to determine the sedimentation rate in the lake. The flux of particles deduced from mass balance calculations based on five isotopes corresponds to the thickness of sediment accumulated since the creation of this artificial lake (that is, 1976). This study emphasises the usefulness of radionuclides as tracers for environmental investigations.

  18. Glacier Mass Balance measurements in Bhutan

    NASA Astrophysics Data System (ADS)

    Jackson, Miriam; Tenzin, Sangay; Tashi, Tshering

    2014-05-01

    Long-term glacier measurements are scarce in the Himalayas, partly due to lack of resources as well as inaccessibility of most of the glaciers. There are over 600 glaciers in Bhutan in the Eastern Himalayas, but no long-term measurements. However, such studies are an important component of hydrological modelling, and especially relevant to the proposed expansion of hydropower resources in this area. Glaciological studies are also critical to understanding the risk of jøkulhlaups or GLOFS (glacier lake outburst floods) from glaciers in this region. Glacier mass balance measurements have been initiated on a glacier in the Chamkhar Chu region in central Bhutan by the Department of Hydro-Met Services in co-operation with the Norwegian Water Resources and Energy Directorate. Chamkhar Chu is the site of two proposed hydropower plants that will each generate over 700 MW, although the present and future hydrological regimes in this basin, and especially the contribution from glaciers, are not well-understood at present. There are about 94 glaciers in the Chamkhar Chhu basin and total glacier area is about 75 sq. km. The glaciers are relatively accessible for the Himalayas, most of them can be reached after only 4-5 days walk from the nearest road. One of the largest, Thana glacier, has been chosen as a mass balance glacier and measurements were initiated in 2013. The glacier area is almost 5 sq. km. and the elevation range is 500 m (5071 m a.s.l. to 5725 m a.s.l.) making it suitable as a benchmark glacier. Preliminary measurements on a smaller, nearby glacier that was visited in 2012 and 2013 showed 1 m of firn loss (about 0.6 m w.eq.) over 12 months.

  19. A nitrogen mass balance for California

    NASA Astrophysics Data System (ADS)

    Liptzin, D.; Dahlgren, R. A.

    2010-12-01

    Human activities have greatly altered the global nitrogen cycle and these changes are apparent in water quality, air quality, ecosystem and human health. However, the relative magnitude of the sources of new reactive nitrogen and the fate of this nitrogen is not well established. Further, the biogeochemical aspects of the nitrogen cycle are often studied in isolation from the economic and social implications of all the transformations of nitrogen. The California Nitrogen Assessment is an interdisciplinary project whose aim is evaluating the current state of nitrogen science, practice, and policy in the state of California. Because of the close proximity of large population centers, highly productive and diverse agricultural lands and significant acreage of undeveloped land, California is a particularly interesting place for this analysis. One component of this assessment is developing a mass balance of nitrogen as well as identifying gaps in knowledge and quantifying uncertainty. The main inputs of new reactive nitrogen to the state are 1) synthetic nitrogen fertilizer, 2) biological nitrogen fixation, and 3) atmospheric nitrogen deposition. Permanent losses of nitrogen include 1) gaseous losses (N2, N2O, NHx, NOy), 2) riverine discharge, 3) wastewater discharge to the ocean, and 4) net groundwater recharge. A final term is the balance of food, feed, and fiber to support the human and animal populations. The largest input of new reactive nitrogen to California is nitrogen fertilizer, but both nitrogen fixation and atmospheric deposition contribute significantly. Non-fertilizer uses, such as the production of nylon and polyurethane, constitutes about 5% of the synthetic N synthesized production. The total nitrogen fixation in California is roughly equivalent on the 400,000 ha of alfalfa and the approximately 40 million ha of natural lands. In addition, even with highly productive agricultural lands, the large population of livestock, in particular dairy cows

  20. Automated chemical mass balance receptor modeling

    SciTech Connect

    Hanrahan, P.L.; Core, J.E.

    1986-09-01

    Chemical mass balance (CMB) receptor modeling provides alternative or complementary methods to dispersion models for apportioning particulate source impacts. This method estimates particulate source contributions at a receptor by comparing the chemistry of the ambient aerosol to the chemistry of the emissions from the various sources. To minimize demands on the analyst and facilitate the processing of large volumes of data, an initial version of an automated CMB model has been developed and is operational on an IBM personal computer as well as on a Harris mini-mainframe computer. Although it currently does not have all the features of the more interactive manual model, it does show promise for reducing man-power demands. The automated model is based on an early version of the EPA CMB model, which has been converted to run on an IBM-PC or compatible microcomputer. It uses the effective variance method. The interactive manual model is also undergoing modifications under an EPA contract. Some of these new features of the EPA model have been included in one version of the automated model.

  1. Estimates of Regional Equilibrium Line Altitudes and Net Mass Balance from MODIS Imagery

    NASA Astrophysics Data System (ADS)

    Shea, J. M.; Menounos, B.; Moore, R. D.

    2011-12-01

    Glacier mass balance is a key variable used to assess the health of glaciers and ice sheets. Estimates of glacier mass balance are required to model the dynamic response of glaciers and ice sheets to climate change, estimate sea-level contribution from surface melt, and document the response of glaciers to climate forcing. Annually resolved estimates of regional mass balance for mountain ranges is often inferred from a sparse network of ground-based measurements of mass balance for individual glaciers. Given that net mass balance is highly correlated with the annual equilibrium line altitude (ELA), we develop an automated approach to estimate the ELA, and by inference net mass balance, on large glaciers and icefields using MODIS 250 m imagery (MOD02QKM). We discriminate areas of bare ice and snow/firn using the product of MODIS' red (0.620 - 0.670 μ m) and near infrared (0.841 - 0.876 μ m) bands. To assess the skill in estimating glacier ELAs, we compare ELAs derived from (1) manual delineation and (2) unsupervised classification of the band product to ground-based observations of ELA and net mass balance at seven long term mass-balance monitoring sites in western North America (Gulkana, Wolverine, Lemon Creek, Taku, Place, Peyto, and South Cascade). Spatial and temporal variations in MODIS-derived ELAs provide an opportunity to validate regional mass-balance models, estimate surface melt contributions to sea-level rise, and examine the cryospheric response to climate change.

  2. Surface Mass Balance of the Columbia Glacier, Alaska, 1978 and 2010 Balance Years

    USGS Publications Warehouse

    O'Neel, Shad

    2012-01-01

    Although Columbia Glacier is one of the largest sources of glacier mass loss in Alaska, surface mass balance measurements are sparse, with only a single data set available from 1978. The dearth of surface mass-balance data prohibits partitioning of the total mass losses between dynamics and surface forcing; however, the accurate inclusion of calving glaciers into predictive models requires both dynamic and climatic forcing of total mass balance. During 2010, the U.S. Geological Survey collected surface balance data at several locations distributed over the surface of Columbia Glacier to estimate the glacier-wide annual balance for balance year 2010 using the 2007 area-altitude distribution. This report also summarizes data collected in 1978, calculates the 1978 annual surface balance, and uses these observations to constrain the 2010 values, particularly the shape of the balance profile. Both years exhibit balances indicative of near-equilibrium surface mass-balance conditions, and demonstrate the importance of dynamic processes during the rapid retreat.

  3. Evapotranspiration: Mass balance measurements compared with flux estimation methods

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Evapotranspiration (ET) may be measured by mass balance methods and estimated by flux sensing methods. The mass balance methods are typically restricted in terms of the area that can be represented (e.g., surface area of weighing lysimeter (LYS) or equivalent representative area of neutron probe (NP...

  4. Mass balance and exergy analysis of a fast pyrolysis system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mass balance closure and exergetic efficiency is evaluated for a bench scale fast pyrolysis system. The USDA Agricultural Research Service (ARS) has developed this system for processing energy crops and agricultural residues for bio-oil (pyrolysis oil or pyrolysis liquids) production. Mass balance c...

  5. DEVELOPMENT OF A CONTAMINANT TRANSPORT AND FATE MASS BALANCE CALIBRATION MODEL FOR LAKE MICHIGAN MASS BALANCE PROJECT (LMMBP)

    EPA Science Inventory

    Lake Michigan Mass Balance Project (LMMBP) was initiated to directly support the development of a lakewide management plan (LaMP) for Lake Michigan. A mass balance modeling approach is proposed for the project to addrss the realtionship between sources of toxic chemicals and thei...

  6. How many stakes are required to measure the mass balance of a glacier?

    USGS Publications Warehouse

    Fountain, A.G.; Vecchia, A.

    1999-01-01

    Glacier mass balance is estimated for South Cascade Glacier and Maclure Glacier using a one-dimensional regression of mass balance with altitude as an alternative to the traditional approach of contouring mass balance values. One attractive feature of regression is that it can be applied to sparse data sets where contouring is not possible and can provide an objective error of the resulting estimate. Regression methods yielded mass balance values equivalent to contouring methods. The effect of the number of mass balance measurements on the final value for the glacier showed that sample sizes as small as five stakes provided reasonable estimates, although the error estimates were greater than for larger sample sizes. Different spatial patterns of measurement locations showed no appreciable influence on the final value as long as different surface altitudes were intermittently sampled over the altitude range of the glacier. Two different regression equations were examined, a quadratic, and a piecewise linear spline, and comparison of results showed little sensitivity to the type of equation. These results point to the dominant effect of the gradient of mass balance with altitude of alpine glaciers compared to transverse variations. The number of mass balance measurements required to determine the glacier balance appears to be scale invariant for small glaciers and five to ten stakes are sufficient.

  7. Assessing streamflow sensitivity to variations in glacier mass balance

    USGS Publications Warehouse

    O'Neel, Shad; Hood, Eran; Arendt, Anthony; Sass, Louis

    2014-01-01

    The purpose of this paper is to evaluate relationships among seasonal and annual glacier mass balances, glacier runoff and streamflow in two glacierized basins in different climate settings. We use long-term glacier mass balance and streamflow datasets from the United States Geological Survey (USGS) Alaska Benchmark Glacier Program to compare and contrast glacier-streamflow interactions in a maritime climate (Wolverine Glacier) with those in a continental climate (Gulkana Glacier). Our overall goal is to improve our understanding of how glacier mass balance processes impact streamflow, ultimately improving our conceptual understanding of the future evolution of glacier runoff in continental and maritime climates.

  8. Juneau Icefield Mass Balance Program 1946-2011

    NASA Astrophysics Data System (ADS)

    Pelto, M.; Kavanaugh, J.; McNeil, C.

    2013-05-01

    The mass balance records of the Lemon Creek Glacier and Taku Glacier observed by the Juneau Icefield Research Program are the longest continuous glacier mass balance data sets in North America. On Taku Glacier annual mass balance averaged +0.40 m a-1 from 1946-1985 and -0.08 m a-1 from 1986-2011. The recent mass balance decline has resulted in the cessation of the long term thickening of the glacier. Mean annual mass balance on Lemon Creek Glacier has declined from -0.30 m a-1 for the 1953-1985 period to -0.60 m a-1 during the 1986-2011 period. The overall mass balance change is -26.6 m water equivalent, a 29 m of ice thinning over the 55 yr. Probing transects above the transient snow line (TSL) indicate a consistent balance gradient from year to year. Observations of the rate of summer TSL rise on Lemon Creek and Taku Glacier indicate a comparatively consistent rate of 3.8 to 4.1 m d-1. The relationship between TSL on Lemon Creek and Taku Glacier to other Juneau Icefield glaciers, Norris, Mendenhall, Herbert, and Eagle, is strong with correlations exceeding 0.82 in all cases. doi:10.5065/D6NZ85N3

  9. Comparative glacio-climatological analysis of mass balance variability along the geographical margin of Europe

    NASA Astrophysics Data System (ADS)

    Lehoczky, Annamária; Kern, Zoltán; Pongrácz, Rita

    2014-05-01

    Glacio-climatological studies recognise glacier mass balance changes as high-confident climate indicators. The climatic sensitivity of a glacier does not simply depend on regional climate variability but also influenced via large- and mesoscale atmospheric circulation patterns. This study focuses on recent changes in the mass balance using records from three border regions of Europe, and investigates the relationships between the seasonal mass balance components, regional climatic conditions, and distant atmospheric forcing. Since glaciers in different macro-climatological conditions (i.e., mid-latitudes or high-latitudes, dry-continental or maritime regions) may present strongly diverse mass balance characteristics, the three analysed regions were selected from different glacierised macroregions (using the database of the World Glacier Monitoring Service). These regions belong to the Caucasus Mountains (Central Europe macroregion), the Polar Ural (Northern Asia macroregion), and Svalbard (Arctic Islands macroregion). The analysis focuses on winter, summer, and annual mass balance series of eight glaciers. The climatic variables (atmospheric pressure, air temperature, precipitation) and indices of teleconnection patterns (e.g., North Atlantic Oscillation, Pacific Decadal Oscillation) are used from the gridded databases of the University of East Anglia, Climatic Research Unit and the National Oceanic and Atmospheric Administration, National Center for Environmental Prediction. However, the period and length of available mass balance data in the selected regions vary greatly (the first full record is in 1958, Polar Ural; the last is in 2010, Caucasus Mountains), a comparative analysis can be carried out for the period of 1968-1981. Since glaciers from different regions respond to large- and mesoscale climatic forcings differently, and because the mass balance of glaciers within a region often co-vary, our specific objectives are (i) to examine the variability and the

  10. Identifying Dynamically Induced Variability in Glacier Mass-Balance Records

    NASA Astrophysics Data System (ADS)

    Christian, J. E.; Siler, N.; Koutnik, M. R.; Roe, G.

    2015-12-01

    Glacier mass-balance (i.e., accumulation vs. ablation) provides a direct indicator of a glacier's relationship with climate. However, mass-balance records contain noise due to internal climate variability (i.e., from stochastic fluctuations in large-scale atmospheric circulation), which can obscure or bias trends in these relatively short timeseries. This presents a challenge in correctly identifying the signature of anthropogenic change. "Dynamical adjustment" is a technique that identifies patterns of variance shared between a climate timeseries of interest (e.g., mass-balance) and independent "predictor" variables associated with large-scale circulation (e.g., Sea Level Pressure, SLP, or Sea Surface Temperature, SST). Extracting the component of variance due to internal variability leaves a residual timeseries for which trends can more confidently be attributed to external forcing. We apply dynamical adjustments based on Partial Least Squares Regression to mass-balance records from South Cascade Glacier in Washington State and Wolverine and Gulkana Glaciers in Alaska, independently analyzing seasonal balance records to assess the dynamical influences on winter accumulation and summer ablation. Seasonally averaged North Pacific SLP and SST fields perform comparably as predictor variables, explaining 50-60% of the variance in winter balance and 30-40% of variance in summer balance for South Cascade and Wolverine Glaciers. Gulkana glacier, located further inland than the other two glaciers, is less closely linked to North Pacific climate variability, with the predictors explaining roughly one-third of variance in its winter and summer balance. We analyze the significance of linear trends in the raw and adjusted mass-balance records, and find that for all three glaciers, a) summer balance shows a statistically significant downward trend that is not substantially altered when dynamically induced variability is removed, and b) winter balance shows no statistically

  11. BTD building uranium mass balance study

    SciTech Connect

    Sutter, S.L.; Johnston, J.W.; Glissmeyer, J.A.; Athey, G.F.

    1985-01-01

    Fifteen test firings of depleted uranium (DU) munitions were made during the qualification study of the new target building at the BTD Range operated by the US Army Combat Systems Test Activity (CSTA) at Aberdeen Proving Ground, Maryland. Following these test firings, the total mass and mass distribution of DU inside the BTD facility was determined to define decontamination requirements for the new target building. 4 references, 17 figures, 17 tables.

  12. Mass balance of the Antarctic ice sheet.

    PubMed

    Wingham, D J; Shepherd, A; Muir, A; Marshall, G J

    2006-07-15

    The Antarctic contribution to sea-level rise has long been uncertain. While regional variability in ice dynamics has been revealed, a picture of mass changes throughout the continental ice sheet is lacking. Here, we use satellite radar altimetry to measure the elevation change of 72% of the grounded ice sheet during the period 1992-2003. Depending on the density of the snow giving rise to the observed elevation fluctuations, the ice sheet mass trend falls in the range -5-+85Gtyr-1. We find that data from climate model reanalyses are not able to characterise the contemporary snowfall fluctuation with useful accuracy and our best estimate of the overall mass trend-growth of 27+/-29Gtyr-1-is based on an assessment of the expected snowfall variability. Mass gains from accumulating snow, particularly on the Antarctic Peninsula and within East Antarctica, exceed the ice dynamic mass loss from West Antarctica. The result exacerbates the difficulty of explaining twentieth century sea-level rise. PMID:16782603

  13. A Simple Watt Balance for the Absolute Determination of Mass

    ERIC Educational Resources Information Center

    Quinn, Terry; Quinn, Lucas; Davis, Richard

    2013-01-01

    A watt balance is an electromechanical device that allows a mass to be determined in terms of measurable electrical and mechanical quantities, themselves traceable to the fundamental constants of physics. International plans are well advanced to redefine the unit of mass, the kilogram, in terms of a fixed numerical value for the Planck constant. A…

  14. Modelling mass balance and temperature sensitivity on Shallap glacier, Peru

    NASA Astrophysics Data System (ADS)

    Gurgiser, W.; Marzeion, B.; Nicholson, L. I.; Ortner, M.; Kaser, G.

    2013-12-01

    Due to pronounced dry seasons in the tropical Andes of Peru glacier melt water is an important factor for year-round water availability for the local society. Andean glaciers have been shrinking during the last decades but present day's magnitudes of glacier mass balance and sensitivities to changes in atmospheric drivers are not well known. Therefore we have calculated spatial distributed glacier mass and energy balance of Shallap glacier (4700 m - 5700 m, 9°S), Cordillera Blanca, Peru, on hourly time steps for the period Sept. 2006 to Aug. 2008 with records from an AWS close to the glacier as model input. Our model evaluation against measured surface height change in the ablation zone of the glacier yields our model results to be reasonable and within an expectable error range. For the mass balance characteristics we found similar vertical gradients and accumulation area ratios but markedly differences in specific mass balance from year to year. The differences were mainly caused by large differences in annual ablation in the glacier area below 5000m. By comparing the meteorological conditions in both years we found for the year with more negative mass balance that total precipitation was only slightly lower but mean annual temperature was higher, thus the fraction of liquid precipitation and the snow line altitude too. As shortwave net energy turned out to be the key driver of ablation in all seasons the deviations in snow line altitude and surface albedo explain most of the deviations in available melt energy. Hence, mass balance of tropical Shallap glacier was not only sensitive to precipitation but also to temperature which has not been expected for glaciers in the Peruvian Andes before. We furthermore have investigated impacts of increasing temperature due to its multiple effects on glacier mass and energy balance (fraction of liquid precipitation, long wave incoming radiation, sensible and latent heat flux). Presenting these results should allow for better

  15. 50 years of mass balance observations at Vernagtferner, Eastern Alps

    NASA Astrophysics Data System (ADS)

    Braun, Ludwig; Mayer, Christoph

    2016-04-01

    The determination and monitoring of the seasonal and annual glacier mass balances of Vernagtferner, Austria, started in 1964 by the Commission of Glaciology, Bavarian Academy of Sciences. Detailed and continuous climate- and runoff measurements complement this mass balance series since 1974. Vernagtferner attracted the attention of scientists since the beginning of the 17th century due to its rapid advances and the resulting glacier lake outburst floods in the Ötztal valley. This is one reason for the first photogrammetric survey in 1889, which was followed by frequent topographic surveys, adding up to more than ten digital elevation models of the glacier until today. By including the known maximum glacier extent at the end of the Little Ice Age in 1845, the geodetic glacier volume balances cover a time span of almost 170 years. The 50 years of glacier mass balance and 40 years of water balance in the drainage basin are therefore embedded in a considerably longer period of glacier evolution, allowing an interpretation within an extended frame of climatology and ice dynamics. The direct mass balance observations cover not only the period of alpine-wide strong glacier mass loss since the beginning of the 1990s. The data also contain the last period of glacier advances between 1970 and 1990. The combination of the observed surface mass exchange and the determined periodic volumetric changes allows a detailed analysis of the dynamic reaction of the glacier over the period of half a century. The accompanying meteorological observations are the basis for relating these reactions to the climatic changes during this period. Vernagtferner is therefore one of the few glaciers in the world, where a very detailed glacier-climate reaction was observed for many decades and can be realistically reconstructed back to the end of the Little Ice Age.

  16. Juneau Icefield Mass Balance Program 1946-2011

    NASA Astrophysics Data System (ADS)

    Pelto, M.; Kavanaugh, J.; McNeil, C.

    2013-11-01

    The annual surface mass balance records of the Lemon Creek Glacier and Taku Glacier observed by the Juneau Icefield Research Program are the longest continuous glacier annual mass balance data sets in North America. Annual surface mass balance (Ba) measured on Taku Glacier averaged +0.40 m a-1 from 1946-1985, and -0.08 m a-1 from 1986-2011. The recent annual mass balance decline has resulted in the cessation of the long-term thickening of the glacier. Mean Ba on Lemon Creek Glacier has declined from -0.30 m a-1 for the 1953-1985 period to -0.60 m a-1 during the 1986-2011 period. The cumulative change in annual surface mass balance is -26.6 m water equivalent, a 29 m of ice thinning over the 55 yr. Snow-pit measurements spanning the accumulation zone, and probing transects above the transient snow line (TSL) on Taku Glacier, indicate a consistent surface mass balance gradient from year to year. Observations of the rate of TSL rise on Lemon Creek Glacier and Taku Glacier indicate a comparatively consistent migration rate of 3.8 to 4.1 m d-1. The relationship between TSL on Lemon Creek Glacier and Taku Glacier to other Juneau Icefield glaciers (Norris, Mendenhall, Herbert, and Eagle) is strong, with correlations exceeding 0.82 in all cases. doi:10.5065/D6NZ85N3

  17. Radionuclide mass balance for the TMI-2 accident: data-base system and preliminary mass balance. Volume 1

    SciTech Connect

    Goldman, M I; Davis, R J; Strahl, J F; Arcieri, W C; Tonkay, D W

    1983-04-01

    After the accident at Three Mile Island, Unit 2 (TMI-2), on March 28, 1979, GEND stated its intention to support an effort to determine, as accurately as possible, the current mass balances of significant radiological toxic species. GEND gave two primary reasons for support this effort: (1) such exercises guarantee completeness of the studies, and (2) mass balance determinations ensure that all important sinks and attentuation mechanisms have been identified. The primary objective of the studies conducted by NUS Corporation was to support the goals of the GEND planners and to continue the mass balance effort by generating a preliminary accounting of key radioactive species following the TMI-2 accident. As a result of these studies, secondary objectives, namely a computerized data base and recommendations, have been achieved to support future work in this area.

  18. CHEMICAL MASS BALANCE MODEL: EPA-CMB8.2

    EPA Science Inventory

    The Chemical Mass Balance (CMB) method has been a popular approach for receptor modeling of ambient air pollutants for over two decades. For the past few years the U.S. Environmental Protection Agency's Office of Research and Development (ORD) and Office of Air Quality Plannin...

  19. Mass balance approaches to understanding evolution of dripwater chemistry

    NASA Astrophysics Data System (ADS)

    Fairchild, I. J.; Baker, A.; Andersen, M. S.; Treble, P. C.

    2015-12-01

    Forward and inverse modelling of dripwater chemistry is a fast-developing area in speleothem science. Such approaches can incorporate theoretical, parameterized or observed relationships between forcing factors and water composition, but at the heart is mass balance: a fundamental principle that provides important constraints. Mass balance has been used in speleothem studies to trace the evolution of dissolved inorganic carbon and carbon isotopes from soil to cave, and to characterize the existence and quantification of prior calcite precipitation (PCP) based on ratios of Mg and Sr to Ca. PCP effects can dominate slow drips, whereas fast drips are more likely to show a residual variability linked to soil-biomass processes. A possible configuration of a more complete mass balance model is illustrated in the figure. Even in humid temperate climates, evapotranspiration can be 50% of total atmospheric precipitation leading to substantially raised salt contents and there can be significant exchange with biomass. In more arid settings, at least seasonal soil storage of salts is likely. Golgotha Cave in SW Australia is in a Mediterranean climate with a strong summer soil moisture deficit. The land surface is forested leading to large ion fluxes related to vegetation. There are also periodic disturbances related to fire. Mass balance approaches have been applied to an 8-year monitoring record. Inter-annual trends of elements coprecipitated in speleothems from fast drips are predicted to be dominated by biomass effects.

  20. LAKE MICHIGAN MASS BALANCE: ATRAZINE MODELING AND LOADS

    EPA Science Inventory

    The Lake Michigan Mass Balance Study measured PCBs, mercury, trans-nonachlor, and atrazine in rivers, the atmosphere, sediments, lake water, and the food chain. A mathematical model will predict what effect reducing pollution will have on the lake, and its large fish (lake trout ...

  1. MODELLING SEDIMENT TRANSPORT FOR THE LAKE MICHIGAN MASS BALANCE PROJECT

    EPA Science Inventory

    A sediment transport model is one component of the overall ensemble of models being developed for the Lake Michigan Mass Balance. The SEDZL model is being applied to simulate the fine-grained sediment transport in Lake Michigan for the 1982-1983 and 1994-1995 periods. Model perf...

  2. LAKE MICHIGAN MASS BALANCE STUDY: PROGNOSIS FOR PCBS

    EPA Science Inventory

    The Lake Michigan Mass Balance Study was conducted to measure and model nutrients, atrazine, PCBs, trans-nonachlor, and mercury to gain a better understanding of the transport and fate of these substances within the system and to aid managers in the environmental decision-making ...

  3. Mass balance and streamflow variability at Place Glacier, Canada, in relation to recent climate fluctuations

    NASA Astrophysics Data System (ADS)

    Moore, R. D.; Demuth, M. N.

    2001-12-01

    Although a great deal of research has focused on the hydrologic effects of climate variability and change, relatively little research has examined the effects on streamflow of interactions between climate variability and change and resulting glacier response. Place Glacier, in the southern Coast Mountains of British Columbia, Canada, has been monitored for mass balance since 1965, and a stream gauge was operated just below the glacier terminus from 1969 to 1989. This paper presents analyses of the mass balance history and streamflow variations in relation to recorded climatic variability.Place Glacier's winter and net balances are correlated with the Pacific Decadal Oscillation (PDO). Summer balance is positively correlated with summer temperature and negatively with the preceding winter balance, which enhances the effects of changes in winter balance on net balance. The well-documented post-1976 shift from the PDO cold phase to the present warm phase initiated a significant and persistent period of more negative net balance and terminal retreat. A reconstruction of net balance extending back to the 1890s, based on a regression with winter precipitation and summer temperature, displays decadal-scale fluctuations consistent with the PDO. Summer streamflow responded to interannual variations in winter snow accumulation and summer temperatures, which control the rate of rise of the glacier snowline and melt rates. After accounting for these influences via regression analysis, August streamflow displayed a negative trend in total runoff. Examination of air photographs and the reconstructed mass balance history suggest that significant firn depletion had occurred prior to 1965, such that the dominant effect of glacier changes was a reduction in ice area, resulting in decreased meltwater production.

  4. A surface mass balance model for the Greenland Ice Sheet

    NASA Astrophysics Data System (ADS)

    Bougamont, Marion; Bamber, Jonathan L.; Greuell, Wouter

    2005-12-01

    A surface mass balance model aimed at being coupled to a Global Circulation Model (GCM) for future climate prediction is described and tested for the Greenland Ice Sheet. The model builds on previous modeling designed to be forced by automatic weather station data, and includes surface energy balance as well as processes occurring near the surface such as water percolation and refreezing. Surface albedo is calculated with a new scheme that differentiates the timescale for aging of wet and dry snow and incorporates the effect of a thin layer of water and/or fresh snow at the surface. The model was driven with automatic weather station data from two sites located in the ablation zone in the Kangerlussuaq area (West Greenland), and calculated reasonable annual mass balance values (within 10% in seven out of eight cases) for four individual and consecutive years (1998-2001), using both measured and calculated albedo. This implies that the albedo parameterization is adequate and climate feedbacks affecting the mass balance are well captured. The model was then applied to a distributed 20-km-resolution grid covering the whole ice sheet, and forced with 10 years of the European Centre for Medium-range Weather Forecast (ECMWF) reanalysis (ERA-40) data. With the aim of coupling the model to a GCM, this study focuses on the ability to model the interannual variability in mass balance rather than to assess the present state of balance of the ice sheet. Modeled spatial and temporal wet zone extent compares well with information derived from passive microwave satellite data.

  5. The climatic mass balance of Svalbard glaciers: a 10-year simulation with a coupled atmosphere-glacier mass balance model

    NASA Astrophysics Data System (ADS)

    Aas, Kjetil S.; Dunse, Thorben; Collier, Emily; Schuler, Thomas V.; Berntsen, Terje K.; Kohler, Jack; Luks, Bartłomiej

    2016-05-01

    In this study we simulate the climatic mass balance of Svalbard glaciers with a coupled atmosphere-glacier model with 3 km grid spacing, from September 2003 to September 2013. We find a mean specific net mass balance of -257 mm w.e. yr-1, corresponding to a mean annual mass loss of about 8.7 Gt, with large interannual variability. Our results are compared with a comprehensive set of mass balance, meteorological, and satellite measurements. Model temperature biases of 0.19 and -1.9 °C are found at two glacier automatic weather station sites. Simulated climatic mass balance is mostly within about 100 mm w.e. yr-1 of stake measurements, and simulated winter accumulation at the Austfonna ice cap shows mean absolute errors of 47 and 67 mm w.e. yr-1 when compared to radar-derived values for the selected years 2004 and 2006. Comparison of modeled surface height changes from 2003 to 2008, and satellite altimetry reveals good agreement in both mean values and regional differences. The largest deviations from observations are found for winter accumulation at Hansbreen (up to around 1000 mm w.e. yr-1), a site where sub-grid topography and wind redistribution of snow are important factors. Comparison with simulations using 9 km grid spacing reveal considerable differences on regional and local scales. In addition, 3 km grid spacing allows for a much more detailed comparison with observations than what is possible with 9 km grid spacing. Further decreasing the grid spacing to 1 km appears to be less significant, although in general precipitation amounts increase with resolution. Altogether, the model compares well with observations and offers possibilities for studying glacier climatic mass balance on Svalbard both historically as well as based on climate projections.

  6. Method of Manufacturing a Micromechanical Oscillating Mass Balance

    NASA Technical Reports Server (NTRS)

    Altemir, David A. (Inventor)

    1999-01-01

    A micromechanical oscillating mass balance and method adapted for measuring minute quantities of material deposited at a selected location, such as during a vapor deposition process. The invention comprises a vibratory composite beam which includes a dielectric layer sandwiched between two conductive layers.The beam is positioned in a magnetic field. An alternating current passes through one conductive layers, the beam oscillates, inducing an output current in the second conductive layer, which is analyzed to determine the resonant frequency of the beam. As material is deposited on the beam, the mass of the beam increases and the resonant frequency of the beam shifts, and the mass added is determined.

  7. A reconciled estimate of ice-sheet mass balance.

    PubMed

    Shepherd, Andrew; Ivins, Erik R; A, Geruo; Barletta, Valentina R; Bentley, Mike J; Bettadpur, Srinivas; Briggs, Kate H; Bromwich, David H; Forsberg, René; Galin, Natalia; Horwath, Martin; Jacobs, Stan; Joughin, Ian; King, Matt A; Lenaerts, Jan T M; Li, Jilu; Ligtenberg, Stefan R M; Luckman, Adrian; Luthcke, Scott B; McMillan, Malcolm; Meister, Rakia; Milne, Glenn; Mouginot, Jeremie; Muir, Alan; Nicolas, Julien P; Paden, John; Payne, Antony J; Pritchard, Hamish; Rignot, Eric; Rott, Helmut; Sørensen, Louise Sandberg; Scambos, Ted A; Scheuchl, Bernd; Schrama, Ernst J O; Smith, Ben; Sundal, Aud V; van Angelen, Jan H; van de Berg, Willem J; van den Broeke, Michiel R; Vaughan, David G; Velicogna, Isabella; Wahr, John; Whitehouse, Pippa L; Wingham, Duncan J; Yi, Donghui; Young, Duncan; Zwally, H Jay

    2012-11-30

    We combined an ensemble of satellite altimetry, interferometry, and gravimetry data sets using common geographical regions, time intervals, and models of surface mass balance and glacial isostatic adjustment to estimate the mass balance of Earth's polar ice sheets. We find that there is good agreement between different satellite methods--especially in Greenland and West Antarctica--and that combining satellite data sets leads to greater certainty. Between 1992 and 2011, the ice sheets of Greenland, East Antarctica, West Antarctica, and the Antarctic Peninsula changed in mass by -142 ± 49, +14 ± 43, -65 ± 26, and -20 ± 14 gigatonnes year(-1), respectively. Since 1992, the polar ice sheets have contributed, on average, 0.59 ± 0.20 millimeter year(-1) to the rate of global sea-level rise. PMID:23197528

  8. A Reconciled Estimate of Ice-Sheet Mass Balance

    NASA Technical Reports Server (NTRS)

    Shepherd, Andrew; Ivins, Erik R.; Geruo, A.; Barletta, Valentia R.; Bentley, Mike J.; Bettadpur, Srinivas; Briggs, Kate H.; Bromwich, David H.; Forsberg, Rene; Galin, Natalia; Horwath, Martin; Jacobs, Stan; Joughin, Ian; King, Matt A.; Lenaerts, Jan T. M.; Li, Jilu; Ligtenberg, Stefan R. M.; Luckman, Adrian; Luthcke, Scott B.; McMillan, Malcolm; Meister, Rakia; Milne, Glenn; Mouginot, Jeremie; Muir, Alan; Nicolas,Julien P.; Paden, John; Payne, Antony J.; Pritchard, Hamish; Rignot, Eric; Rott, Helmut; Sorensen, Louise Sandberg; Scambos, Ted A.; Yi, Dohngui; Zwally, H. Jay

    2012-01-01

    We combined an ensemble of satellite altimetry, interferometry, and gravimetry data sets using common geographical regions, time intervals, and models of surface mass balance and glacial isostatic adjustment to estimate the mass balance of Earth's polar ice sheets. We find that there is good agreement between different satellite methods-especially in Greenland and West Antarctica-and that combining satellite data sets leads to greater certainty. Between 1992 and 2011, the ice sheets of Greenland, East Antarctica, West Antarctica, and the Antarctic Peninsula changed in mass by -142 plus or minus 49, +14 plus or minus 43, -65 plus or minus 26, and -20 plus or minus 14 gigatonnes year(sup -1), respectively. Since 1992, the polar ice sheets have contributed, on average, 0.59 plus or minus 0.20 millimeter year(sup -1) to the rate of global sea-level rise.

  9. LINKING GREAT WATERSHEDS WITH LAKE MICHIGAN: THE LAKE MICHIGAN MASS BALANCE STUDY

    EPA Science Inventory

    An overview of the Lake Michigan Mass Balance Study -- which is focusing on atrazine, PCBs, nutrients, suspended solids, trans-nonachlor, and mercury. The relative contribution of contaminants to Lake Michigan will be examined for all major watersheds in the basin. - - - Further ...

  10. Isospin effects on the mass dependence of the balance energy

    SciTech Connect

    Gautam, Sakshi; Sood, Aman D.

    2010-07-15

    We study the effect of isospin degree of freedom on balance energy throughout the mass range between 50 and 350 for two sets of isotopic systems with N/A= 0.54 and 0.57 as well as isobaric systems with N/A= 0.5 and 0.58. Our findings indicate that different values of balance energy for two isobaric systems may be mainly due to the Coulomb repulsion. We also demonstrate clearly the dominance of Coulomb repulsion over symmetry energy.

  11. Mass balance investigation of alpine glaciers through LANDSAT TM data

    NASA Technical Reports Server (NTRS)

    Bayr, Klaus J.

    1989-01-01

    An analysis of LANDSAT Thematic Mapper (TM) data of the Pasterze Glacier and the Kleines Fleisskees in the Austrian Alps was undertaken and compared with meteorological data of nearby weather stations. Alpine or valley glaciers can be used to study regional and worldwide climate changes. Alpine glaciers respond relatively fast to a warming or cooling trend in temperature through an advance or a retreat of the terminus. In addition, the mass balance of the glacier is being affected. Last year two TM scenes of the Pasterze Glacier of Aug. 1984 and Aug. 1986 were used to study the difference in reflectance. This year, in addition to the scenes from last year, one MSS scene of Aug. 1976 and a TM scene from 1988 were examined for both the Pasterze Glacier and the Kleines Fleisskees. During the overpass of the LANDSAT on 6 Aug. 1988 ground truthing on the Pasterze Glacier was undertaken. The results indicate that there was considerable more reflectance in 1976 and 1984 than in 1986 and 1988. The climatological data of the weather stations Sonnblick and Rudolfshuette were examined and compared with the results found through the LANDSAT data. There were relations between the meteorological and LANDSAT data: the average temperature over the last 100 years showed an increase of .4 C, the snowfall was declining during the same time period but the overall precipitation did not reveal any significant change over the same period. With the use of an interactive image analysis computer, the LANDSAT scenes were studied. The terminus of the Pasterze Glacier retreated 348 m and the terminus of the Kleines Fleisskees 121 m since 1965. This approach using LANDSAT MSS and TM digital data in conjunction with meteorological data can be effectively used to monitor regional and worldwide climate changes.

  12. Origin of howardites, diogenites and eucrites - A mass balance constraint

    NASA Technical Reports Server (NTRS)

    Warren, P. H.

    1985-01-01

    Two petrogenetic models for the noncumulate-basaltic parts of howardite meteorites are discussed. A mass balance constraint is developed which indicates that more than half of the basaltic components in howardites formed as residual liquids from fractional crystallization of melts that had earlier produced diogentelike pyroxene cumulate components. Other model constriants involving scandium trends, clustering near olivine-pyroxene-plagioclase peritectic, and MgO/(MgO + FeO) ratios are discussed.

  13. The Ice Sheet Mass Balance Inter-comparison Exercise

    NASA Astrophysics Data System (ADS)

    Shepherd, A.; Ivins, E. R.

    2015-12-01

    Fluctuations in the mass of ice stored in Antarctica and Greenland are of considerable societal importance. The Ice Sheet Mass Balance Inter-Comparison Exercise (IMBIE) is a joint-initiative of ESA and NASA aimed at producing a single estimate of the global sea level contribution to polar ice sheet losses. Within IMBIE, estimates of ice sheet mass balance are developed from a variety of satellite geodetic techniques using a common spatial and temporal reference frame and a common appreciation of the contributions due to external signals. The project brings together the laboratories and space agencies that have been instrumental in developing independent estimates of ice sheet mass balance to date. In its first phase, IMBIE involved 27 science teams, and delivered a first community assessment of ice sheet mass imbalance to replace 40 individual estimates. The project established that (i) there is good agreement between the three main satellite-based techniques for estimating ice sheet mass balance, (ii) combining satellite data sets leads to significant improvement in certainty, (iii) the polar ice sheets contributed 11 ± 4 mm to global sea levels between 1992 and 2012, and (iv) that combined ice losses from Antarctica and Greenland have increased over time, rising from 10% of the global trend in the early 1990's to 30% in the late 2000's. Demand for an updated assessment has grown, and there are now new satellite missions, new geophysical corrections, new techniques, and new teams producing data. The period of overlap between independent satellite techniques has increased from 5 to 12 years, and the full period of satellite data over which an assessment can be performed has increased from 19 to 40 years. It is also clear that multiple satellite techniques are required to confidently separate mass changes associated with snowfall and ice dynamical imbalance - information that is of critical importance for climate modelling. This presentation outlines the approach

  14. Stable isotope mass balance of lakes: a contemporary perspective (Invited)

    NASA Astrophysics Data System (ADS)

    Gibson, J. J.; Birks, S. J.; YI, Y.; Jasechko, S.

    2013-12-01

    Stable isotopes are widely used in paleoclimate studies of lakes to reconstruct water balance and/or climatic conditions, but there are a variety of assumptions that are often made to simplify and operationalize the isotope transfer functions. Based on recent studies conducted on a wide range of lakes across North America, as well as a comprehensive compilation of existing data from around the globe, we present contemporary examples of stable-isotope mass-balance studies based on site-specific to regional lake datasets. We illustrate the need in most cases to understand and characterize the local climate and hydrological setting to accurately model the observed isotopic enrichment, as well as the importance of amount-weighting liquid fluxes and evaporation-flux-weighting vapour fluxes. Potential complications due to atmospheric feedback are also explored by presenting a new analysis of the Laurentian Great Lakes where we apply a model that considers the timing of evaporation, which occurs mainly in the winter, and accounts for downwind lake effects, humidity and isotopic build-up in the boundary layer. One future opportunity of lake-based paleoclimate research may be to develop controlled studies that allow for specific atmospheric or water-balance processes to be targeted and reconstructed. We also show relationships between selected water quality indicators and isotope-based water balance indicators that should, in principle, be preserved in the lake sediment record.

  15. Selenium mass balance in the Great Salt Lake, Utah

    USGS Publications Warehouse

    Diaz, X.; Johnson, W.P.; Naftz, D.L.

    2009-01-01

    A mass balance for Se in the south arm of the Great Salt Lake was developed for September 2006 to August 2007 of monitoring for Se loads and removal flows. The combined removal flows (sedimentation and volatilization) totaled to a geometric mean value of 2079??kg Se/yr, with the estimated low value being 1255??kg Se/yr, and an estimated high value of 3143??kg Se/yr at the 68% confidence level. The total (particulates + dissolved) loads (via runoff) were about 1560??kg Se/yr, for which the error is expected to be ?? 15% for the measured loads. Comparison of volatilization to sedimentation flux demonstrates that volatilization rather than sedimentation is likely the major mechanism of selenium removal from the Great Salt Lake. The measured loss flows balance (within the range of uncertainties), and possibly surpass, the measured annual loads. Concentration histories were modeled using a simple mass balance, which indicated that no significant change in Se concentration was expected during the period of study. Surprisingly, the measured total Se concentration increased during the period of the study, indicating that the removal processes operate at their low estimated rates, and/or there are unmeasured selenium loads entering the lake. The selenium concentration trajectories were compared to those of other trace metals to assess the significance of selenium concentration trends. ?? 2008 Elsevier B.V.

  16. Mass and energy balance of the cold Io torus

    NASA Technical Reports Server (NTRS)

    Moreno, M. A.; Barbosa, D. D.

    1986-01-01

    A new model of the cold Io torus is described. Ions and energy are injected into the system by independent processes so that the mass balance is isolated from the energy balance. The primary source of energy is local ionization and acceleration of hot pickup ions resulting from charge exchange between thermal ions and an extended cloud of Iogenic sulfur and oxygen atoms. The primary energy loss mechanism of the plasma is collisionally excited line emission at optical wavelengths. The primary ion source is radial diffusion inward from the hot torus on a time scale of 140-710 days. The primary ion loss mechanism is a novel two-step enhanced recombination mechanism involving charge exchange between thermal ions and an extended cloud of neutral SO2 molecules, followed by rapid dissociative recombination of the resultant molecular ion. The model provides a self-consistent solution which reconciles a number of diverse observations with known physical processes.

  17. Generation of artificial gravity in two-mass systems without balancing

    NASA Astrophysics Data System (ADS)

    Samarov, N. G.; Skriabin, L. P.

    The use of spacecraft rotation as a method of generating artificial gravity is examined for a system consisting of a space station and an attached module (i.e., a two-mass system). It is shown that flexible coupling with nonlinear characteristics is a necessary condition for the balancing of the space station without the use of a special automatic balancing system. However, during the docking and maneuvering, the coupling between the station and the module must be rigid. A possible solution is the use of a combination coupling which allows the transition from rigid to flexible coupling and vice versa.

  18. The mass balance of earthquakes and earthquake sequences

    NASA Astrophysics Data System (ADS)

    Marc, O.; Hovius, N.; Meunier, P.

    2016-04-01

    Large, compressional earthquakes cause surface uplift as well as widespread mass wasting. Knowledge of their trade-off is fragmentary. Combining a seismologically consistent model of earthquake-triggered landsliding and an analytical solution of coseismic surface displacement, we assess how the mass balance of single earthquakes and earthquake sequences depends on fault size and other geophysical parameters. We find that intermediate size earthquakes (Mw 6-7.3) may cause more erosion than uplift, controlled primarily by seismic source depth and landscape steepness, and less so by fault dip and rake. Such earthquakes can limit topographic growth, but our model indicates that both smaller and larger earthquakes (Mw < 6, Mw > 7.3) systematically cause mountain building. Earthquake sequences with a Gutenberg-Richter distribution have a greater tendency to lead to predominant erosion, than repeating earthquakes of the same magnitude, unless a fault can produce earthquakes with Mw > 8 or more.

  19. Energy and Mass Balance At Gran Campo Nevado, Patagonia, Chile

    NASA Astrophysics Data System (ADS)

    Schneider, C.; Kilian, R.; Casassa, G.

    The Gran Campo Nevado (GCN) Ice Cap on Peninsula Muñoz Gamero, Chile, is lo- cated in the southernmost part of the Patagonian Andes at 53S. It comprises an ice cap and numerous outlet glaciers which mostly end in proglacial lakes at sea level. The total ice covered area sums up to approximately 250 km2. GCN forms the only major ice body between the Southern Patagonian Icefield and the Street of Magallan. Its almost unique location in the zone of the all-year westerlies makes it a region of key interest in terms of glacier and climate change studies of the westwind zone of the Southern Hemisphere. Mean annual temperature of approximately +5C at sea level and high precipitation of about 8.000 mm per year lead to an extreme turn-over of ice mass from the accumulation area of the GCN Ice Cap to the ablation areas of the outlet glaciers. Since October 1999 an automated weather station (AWS) is run continuously in the area at Bahia Bahamondes for monitoring climate parameters. From February to April 2000 an additional AWS was operated on Glaciar Lengua a small outlet glacier of GCN to the north-west. Ablation has been measured at stakes during the same pe- riod. The aim of this study, was to obtain point energy and mass balance on Glaciar Lengua. The work was conducted as part of the international and interdisciplinary working group SGran Campo NevadoT and supported by the German Research Foun- & cedil;dation (DFG). Energy balance was calculated using the bulk approach formulas and calibrated to the measured ablation. It turns out, that sensible heat transfer is the major contribution to the energy balance. Since high cloud cover rates prevail, air tempera- ture is the key factor for the energy balance of the glacier. Despite high rain fall rates, energy input from rain fall is of only minor importance to the overall energy balance. From the energy balance computed, it was possible to derive summer-time degree-day factors for Glaciar Lengua. With data from the nearby

  20. Mass balance assessment for mercury in Lake Champlain

    USGS Publications Warehouse

    Gao, N.; Armatas, N.G.; Shanley, J.B.; Kamman, N.C.; Miller, E.K.; Keeler, G.J.; Scherbatskoy, T.; Holsen, T.M.; Young, T.; McIlroy, L.; Drake, S.; Olsen, Bill; Cady, C.

    2006-01-01

    A mass balance model for mercury in Lake Champlain was developed in an effort to understand the sources, inventories, concentrations, and effects of mercury (Hg) contamination in the lake ecosystem. To construct the mass balance model, air, water, and sediment were sampled as a part of this project and other research/monitoring projects in the Lake Champlain Basin. This project produced a STELLA-based computer model and quantitative apportionments of the principal input and output pathways of Hg for each of 13 segments in the lake. The model Hg concentrations in the lake were consistent with measured concentrations. Specifically, the modeling identified surface water inflows as the largest direct contributor of Hg into the lake. Direct wet deposition to the lake was the second largest source of Hg followed by direct dry deposition. Volatilization and sedimentation losses were identified as the two major removal mechanisms. This study significantly improves previous estimates of the relative importance of Hg input pathways and of wet and dry deposition fluxes of Hg into Lake Champlain. It also provides new estimates of volatilization fluxes across different lake segments and sedimentation loss in the lake. ?? 2006 American Chemical Society.

  1. Prescribing hemodialysis using a weekly urea mass balance model.

    PubMed

    Leypoldt, J K; Kablitz, C; Gregory, M C; Senekjian, H O; Cheung, A K

    1991-01-01

    Prescribing hemodialysis by monitoring only predialysis BUN concentrations is not sufficient to guarantee adequate therapy. Results from the National Cooperative Dialysis Study have suggested that hemodialysis therapy is adequate if the protein catabolic rate is maintained greater than 1 g/day/kg body weight and simultaneously if sufficient hemodialysis is prescribed to maintain either a time-averaged BUN concentration (TACurea) less than 50 mg/dl or a value of Kt/V greater than unity. In the present study mathematical relationships were derived from a weekly urea mass balance model that permit an evaluation of TACurea and of protein catabolism via the urea generation rate (G) without the need for conventional urea kinetic modeling. The parameters TACurea and G were simply calculated from a midweek predialysis BUN concentration (BUNMW) by: TACurea = 0.7 BUNMW G = 0.7 BUNMW(Kr + Kd tau/T) where Kr, Kd, tau and T denote residual renal urea clearance, dialyzer urea clearance, number of minutes of hemodialysis per week, and number of minutes total in a week, respectively. Clinical results from 139 modeling sessions on 91 patients demonstrated that TACurea and G derived from urea kinetic modeling correlated highly with those calculated from the above equations (r = 0.96 and 0.94, respectively). It is concluded that individualized hemodialysis prescription and adequacy of therapy can be assessed by monitoring TACurea and G by calculation from a weekly urea mass balance model. PMID:1819316

  2. A Novel and Low Cost Sea Ice Mass Balance Buoy.

    NASA Astrophysics Data System (ADS)

    Jackson, Keith; Meldrum, David; Wilkinson, Jeremy; Maksym, Ted; Beckers, Justin; Haas, Christian

    2013-04-01

    Understanding of sea ice mass balance processes requires continuous monitoring of the seasonal evolution of ice thickness. While autonomous ice mass balance buoys (IMBs) deployed over the past two decades have contributed to our understanding of ice growth and decay processes, deployment has been limited, in part, by the cost of such systems. Routine, basin-wide monitoring of the ice cover is realistically achievable through a network of reliable and affordable autonomous instrumentation. We describe the development of a novel autonomous platform and sensor that replaces the traditional thermistors string for monitoring temperature profiles in the ice and snow using a chain of inexpensive digital temperature chip sensors linked by a single-wire data bus. By incorporating a heating element on each sensor, the instrument is capable of resolving material interfaces (e.g. air-snow and ice-ocean boundaries) even under isothermal conditions. The instrument is small, low-cost and easy to deploy. Field and laboratory tests of the sensor chain demonstrate that the technology can reliably resolve material boundaries to within a few centimetres and over 50 scientific deployments have been made with encouraging results. The discrimination between different media based on sensor thermal response is weak in some deployments and efforts to optimise the measurement continue.

  3. Deducing high-altitude precipitation from glacier mass balance measurements

    NASA Astrophysics Data System (ADS)

    Giesen, Rianne H.; Immerzeel, Walter W.; Wanders, Niko

    2016-04-01

    The spatial distribution of precipitation in mountainous terrain is generally not well known due to underrepresentation of gauge observations at higher elevations. Precipitation tends to increase with elevation, but since observations are mainly performed in the valleys, the vertical precipitation gradient cannot be deduced from these measurements. Furthermore, the spatial resolution of gridded meteorological data is often too coarse to resolve individual mountain chains. Still, a reliable estimate of high-elevation precipitation is required for many hydrological applications. We present a method to determine the vertical precipitation gradient in mountainous terrain, making use of glacier mass balance observations. These measurements have the advantage that they provide a basin-wide precipitation estimate at high elevations. The precipitation gradient is adjusted until the solid precipitation over the glacier area combined with the calculated melt gives the measured annual glacier mass balance. Results for the glacierized regions in Central Europe and Scandinavia reveal spatially coherent patterns, with predominantly positive precipitation gradients ranging from -4 to +28 % (100 m)‑1. In some regions, precipitation amounts at high elevations are up to four times as large as in the valleys. A comparison of the modelled winter precipitation with observed snow accumulation on glaciers shows a good agreement. Precipitation measured at the few high-altitude meteorological stations is generally lower than our estimate, which may result from precipitation undercatch. Our findings will improve the precipitation forcing for glacier modelling and hydrological studies in mountainous terrain.

  4. Mass balance of dioxins over a cement kiln in China.

    PubMed

    Li, Yeqing; Chen, Tong; Zhang, Jiang; Meng, Weijie; Yan, Mi; Wang, Huanzhong; Li, Xiaodong

    2015-02-01

    The cement production process may be a potential source of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs, "dioxins"), due to the widespread distribution of dioxins and potential precursors in raw materials and to conditions favorable to de novo formation in the heat exchangers. The emission, gas/particle distribution, and mass balance of PCDD/Fs were investigated at a typical state-of-the-art Chinese cement kiln. Input and output inventories were established for three campaigns, including two in normal operation and one while co-processing refuse derived fuel (RDF). Sample analysis from stack gas, cement kiln dust, raw meal, fly dust and clinker for the analysis of PCDD/Fs were reported in this study. Dioxins were also analyzed at various positions in the pre-heater, presenting an adsorption-desorption circulation process of PCDD/Fs. The over-all dioxin mass balance was negative, indicating that this cement kiln is not a source but a sink process of dioxins. PMID:25532674

  5. Estimating nutrient loadings using chemical mass balance approach.

    PubMed

    Jain, C K; Singhal, D C; Sharma, M K

    2007-11-01

    The river Hindon is one of the important tributaries of river Yamuna in western Uttar Pradesh (India) and carries pollution loads from various municipal and industrial units and surrounding agricultural areas. The main sources of pollution in the river include municipal wastes from Saharanpur, Muzaffarnagar and Ghaziabad urban areas and industrial effluents of sugar, pulp and paper, distilleries and other miscellaneous industries through tributaries as well as direct inputs. In this paper, chemical mass balance approach has been used to assess the contribution from non-point sources of pollution to the river. The river system has been divided into three stretches depending on the land use pattern. The contribution of point sources in the upper and lower stretches are 95 and 81% respectively of the total flow of the river while there is no point source input in the middle stretch. Mass balance calculations indicate that contribution of nitrate and phosphate from non-point sources amounts to 15.5 and 6.9% in the upper stretch and 13.1 and 16.6% in the lower stretch respectively. Observed differences in the load along the river may be attributed to uncharacterized sources of pollution due to agricultural activities, remobilization from or entrainment of contaminated bottom sediments, ground water contribution or a combination of these sources. PMID:17616829

  6. Atmospheric methyl bromide: Trends and global mass balance

    SciTech Connect

    Khalil, M.A.K.; Rasmussen, R.A.; Gunawardena, R. )

    1993-02-20

    Atmospheric methyl bromide is of considerable environmental importance as the largest reservoir of gaseous bromine in the atmosphere. Bromine gases can catalytically destroy stratospheric ozone. Since agricultural activities, automobiles, biomass burning, and other human activities produce CH[sub 3]Br, it is of interest to know its global mass balance and particularly the specific sources and sinks. In this paper the authors provide a decadal time series of global CH[sub 3]Br concentrations in the Earth's atmosphere. The data show that average concentrations are about 10 pptv and during the last 4 years may be increasing at 0.3 [plus minus] 0.1 pptv/yr (3%/yr [plus minus] 1%/yr). They estimate that the atmospheric lifetime of CH[sub 3]Br that is due to reaction with OH, is about 2 years, resulting in a calculated global emission rate of about 100 Gy/yr. Ocean supersaturations of 140-180% are observed, and atmospheric concentrations over the open oceans are higher than at comparably located coastal sites. The ocean source is estimated to be about 35 Gg/yr. The remaining emissions must come from other natural sources and anthropogenic activities. The results are based on some 2,200 samples obtained over more than a decade. Mass balance calculations explain most aspects of the present data but other implications are not easily reconciled, leaving open the possibility of undiscovered sources and sinks. 20 refs., 5 figs., 4 tabs.

  7. Mass Balance of Perfluoroalkyl Acids in the Baltic Sea

    PubMed Central

    2013-01-01

    A mass balance was assembled for perfluorohexanoic acid (PFHxA), perfluorooctanoic acid (PFOA), perfluorodecanoic acid (PFDA), and perfluorooctanesulfonic acid (PFOS) in the Baltic Sea. Inputs (from riverine discharge, atmospheric deposition, coastal wastewater discharges, and the North Sea) and outputs (to sediment burial, transformation of the chemical, and the North Sea), as well as the inventory in the Baltic Sea, were estimated from recently published monitoring data. Formation of the chemicals in the water column from precursors was not considered. River inflow and atmospheric deposition were the dominant inputs, while wastewater treatment plant (WWTP) effluents made a minor contribution (<5%). A mass balance of the Oder River watershed was assembled to explore the sources of the perfluoroalkyl acids (PFAAs) in the river inflow. It indicated that WWTP effluents made only a moderate contribution to riverine discharge (21% for PFOA, 6% for PFOS), while atmospheric deposition to the watershed was 1–2 orders of magnitude greater than WWTP discharges. The input to the Baltic Sea exceeded the output for all four PFAAs, suggesting that inputs were higher during 2005–2010 than during the previous 20 years despite efforts to reduce emissions of PFAAs. One possible explanation is the retention and delayed release of PFAAs from atmospheric deposition in the soils and groundwater of the watershed. PMID:23528236

  8. Assessment Of Errors In Long-Term Mass Balance Records From Alaska, USA

    NASA Astrophysics Data System (ADS)

    March, R. S.; van Beusekom, A. E.; O'Neel, S.

    2009-12-01

    The USGS maintains a long-term glacier mass balance monitoring program at Gulkana and Wolverine glaciers in Alaska. The records produced by this program are a major component of the world’s mountain glacier balance inventory due to the scarcity of such long-term measurements. Recent data that show rapid glacier volume loss in Alaska further emphasize the importance of these records. An integral part of the long-term mass balance program is repeated assessment of the validity of the methods because bias errors in mass balance data are cumulative. Long-term glacier mass balance records in Alaska have previously been shown to be in good agreement with geodetically determined volume changes despite a minimal network of mass balance stakes. Because the rates of negative mass balance and change in glacier geometry have recently increased, this work reassess whether or not the existing stake networks and method of determining glacier-average balance are still working adequately.

  9. Mass balance model parameter transferability on a tropical glacier

    NASA Astrophysics Data System (ADS)

    Gurgiser, Wolfgang; Mölg, Thomas; Nicholson, Lindsey; Kaser, Georg

    2013-04-01

    The mass balance and melt water production of glaciers is of particular interest in the Peruvian Andes where glacier melt water has markedly increased water supply during the pronounced dry seasons in recent decades. However, the melt water contribution from glaciers is projected to decrease with appreciable negative impacts on the local society within the coming decades. Understanding mass balance processes on tropical glaciers is a prerequisite for modeling present and future glacier runoff. As a first step towards this aim we applied a process-based surface mass balance model in order to calculate observed ablation at two stakes in the ablation zone of Shallap Glacier (4800 m a.s.l., 9°S) in the Cordillera Blanca, Peru. Under the tropical climate, the snow line migrates very frequently across most of the ablation zone all year round causing large temporal and spatial variations of glacier surface conditions and related ablation. Consequently, pronounced differences between the two chosen stakes and the two years were observed. Hourly records of temperature, humidity, wind speed, short wave incoming radiation, and precipitation are available from an automatic weather station (AWS) on the moraine near the glacier for the hydrological years 2006/07 and 2007/08 while stake readings are available at intervals of between 14 to 64 days. To optimize model parameters, we used 1000 model simulations in which the most sensitive model parameters were varied randomly within their physically meaningful ranges. The modeled surface height change was evaluated against the two stake locations in the lower ablation zone (SH11, 4760m) and in the upper ablation zone (SH22, 4816m), respectively. The optimal parameter set for each point achieved good model skill but if we transfer the best parameter combination from one stake site to the other stake site model errors increases significantly. The same happens if we optimize the model parameters for each year individually and transfer

  10. Rising river flows and glacial mass balance in central Karakoram

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Biswajit; Khan, Asif

    2014-05-01

    glacial mass balance in central Karakoram is nearly neutral. The rising river flows accompanying non-negative glacier mass balance are consistent with predicted future river flows derived from hydrologic modeling coupled with a climate projection suggesting increasing temperature and precipitation with unchanged glacier covers. This investigation reconciles two apparently contradictory observations namely rising river flows and either zero or slightly positive mass balance of central Karakoram glaciers.

  11. Enforcing elemental mass and energy balances for reduced order models

    SciTech Connect

    Ma, J.; Agarwal, K.; Sharma, P.; Lang, Y.; Zitney, S.; Gorton, I.; Agawal, D.; Miller, D.

    2012-01-01

    Development of economically feasible gasification and carbon capture, utilization and storage (CCUS) technologies requires a variety of software tools to optimize the designs of not only the key devices involved (e., g., gasifier, CO{sub 2} adsorber) but also the entire power generation system. High-fidelity models such as Computational Fluid Dynamics (CFD) models are capable of accurately simulating the detailed flow dynamics, heat transfer, and chemistry inside the key devices. However, the integration of CFD models within steady-state process simulators, and subsequent optimization of the integrated system, still presents significant challenges due to the scale differences in both time and length, as well the high computational cost. A reduced order model (ROM) generated from a high-fidelity model can serve as a bridge between the models of different scales. While high-fidelity models are built upon the principles of mass, momentum, and energy conservations, ROMs are usually developed based on regression-type equations and hence their predictions may violate the mass and energy conservation laws. A high-fidelity model may also have the mass and energy balance problem if it is not tightly converged. Conservations of mass and energy are important when a ROM is integrated to a flowsheet for the process simulation of the entire chemical or power generation system, especially when recycle streams are connected to the modeled device. As a part of the Carbon Capture Simulation Initiative (CCSI) project supported by the U.S. Department of Energy, we developed a software framework for generating ROMs from CFD simulations and integrating them with Process Modeling Environments (PMEs) for system-wide optimization. This paper presents a method to correct the results of a high-fidelity model or a ROM such that the elemental mass and energy are conserved perfectly. Correction factors for the flow rates of individual species in the product streams are solved using a

  12. Balancing mass and momentum in the Local Group

    NASA Astrophysics Data System (ADS)

    Diaz, J. D.; Koposov, S. E.; Irwin, M.; Belokurov, V.; Evans, N. W.

    2014-09-01

    In the rest frame of the Local Group (LG), the total momentum of the Milky Way (MW) and Andromeda (M31) should balance to zero. We use this fact to constrain new solutions for the solar motion with respect to the LG centre of mass, the total mass of the LG, and the individual masses of M31 and the MW. Using the set of remote LG galaxies at >350 kpc from the MW and M31, we find that the solar motion has amplitude V⊙ = 299 ± 15 km s-1 in a direction pointing towards galactic longitude l⊙ = 98.4° ± 3.6° and galactic latitude b⊙ = -5.9° ± 3.0°. The velocities of M31 and the MW in this rest frame give a direct measurement of their mass ratio, for which we find log10(MM31/MMW) = 0.36 ± 0.29. We combine these measurements with the virial theorem to estimate the total mass within the LG as MLG = (2.5 ± 0.4) × 1012 M⊙. Our value for MLG is consistent with the sum of literature values for MMW and MM31. This suggests that the mass of the LG is almost entirely located within the two largest galaxies rather than being dispersed on larger scales or in a background medium. The outskirts of the LG are seemingly rather empty. Combining our measurement for MLG and the mass ratio, we estimate the individual masses of the MW and M31 to be MMW = (0.8 ± 0.5) × 1012 M⊙ and MM31 = (1.7 ± 0.3) × 1012 M⊙, respectively. Our analysis favours M31 being more massive than the MW by a factor of ˜2.3, and the uncertainties allow only a small probability (9.8 per cent) that the MW is more massive. This is consistent with other properties such as the maximum rotational velocities, total stellar content, and numbers of globular clusters and dwarf satellites, which all suggest that MM31/MMW > 1.

  13. OXALATE MASS BALANCE DURING CHEMICAL CLEANING IN TANK 6F

    SciTech Connect

    Poirier, M.; Fink, S.

    2011-07-22

    The Savannah River Remediation (SRR) is preparing Tank 6F for closure. The first step in preparing the tank for closure is mechanical sludge removal. Following mechanical sludge removal, SRS performed chemical cleaning with oxalic acid to remove the sludge heel. Personnel are currently assessing the effectiveness of the chemical cleaning to determine whether the tank is ready for closure. SRR personnel collected liquid samples during chemical cleaning and submitted them to Savannah River National Laboratory (SRNL) for analysis. Following chemical cleaning, they collected a solid sample (also known as 'process sample') and submitted it to SRNL for analysis. The authors analyzed these samples to assess the effectiveness of the chemical cleaning process. Analysis of the anions showed the measured oxalate removed from Tank 6F to be approximately 50% of the amount added in the oxalic acid. To close the oxalate mass balance, the author collected solid samples, leached them with nitric acid, and measured the concentration of cations and anions in the leachate. Some conclusions from this work are: (1) Approximately 65% of the oxalate added as oxalic acid was removed with the decanted liquid. (2) Approximately 1% of the oxalate (added to the tank as oxalic acid) formed precipitates with compounds such as nickel, manganese, sodium, and iron (II), and was dissolved with nitric acid. (3) As much as 30% of the oxalate may have decomposed forming carbon dioxide. The balance does not fully account for all the oxalate added. The offset represents the combined uncertainty in the analyses and sampling.

  14. Melting standardized aluminum scrap: A mass balance model for europe

    NASA Astrophysics Data System (ADS)

    Boin, U. M. J.; Bertram, M.

    2005-08-01

    Although individual aluminum recycling companies have good knowledge of scrap in terms of its characteristic metal yield during melting, an overall view of this industry is still missing. An aluminum mass balance for the aluminum recycling industry in the European Union member states from 1995 to 2004 (EU-15) has been carried out. The objective was to increase the transparency of the complex recycling system and to determine how resource-conservative the industry is when melting aluminum scrap. Results show that in 2002, about 7 million tonnes of purchased, tolled, and internal scrap—with a metal content of 94%—were recycled in the EU-15. By comparing the net metal input to the final product, the study finds a very respectable metal recovery rate of 98%.

  15. Mass-balance model for predicting nitrate in ground water

    USGS Publications Warehouse

    Frimpter, Michael H.; Donohue, John J.; Rapacz, Michael V.

    1990-01-01

    A mass-balance accounting model can be used to guide the management of septic systems and fertilizers to control the degradation of ground-water quality in zones of an aquifer that contribute water to public-supply wells. The nitrate concentration of the mixture in the well can be predicted for steady-state conditions by calculating the concentration that results from the total weight of nitrogen and total volume of water entering the zone of contribution to the well. These calculations will allow water-quality managers to predict the nitrate concentrations that would be produced by different types and levels of development, and to plan development accordingly. Computations for different development schemes provide a technical basis for planners and managers to compare water-quality effects and to select alternatives that limit nitrate concentration in wells.

  16. Maintaining Atmospheric Mass and Water Balance Within Reanalysis

    NASA Technical Reports Server (NTRS)

    Takacs, Lawrence L.; Suarez, Max; Todling, Ricardo

    2015-01-01

    This report describes the modifications implemented into the Goddard Earth Observing System Version-5 (GEOS-5) Atmospheric Data Assimilation System (ADAS) to maintain global conservation of dry atmospheric mass as well as to preserve the model balance of globally integrated precipitation and surface evaporation during reanalysis. Section 1 begins with a review of these global quantities from four current reanalysis efforts. Section 2 introduces the modifications necessary to preserve these constraints within the atmospheric general circulation model (AGCM), the Gridpoint Statistical Interpolation (GSI) analysis procedure, and the Incremental Analysis Update (IAU) algorithm. Section 3 presents experiments quantifying the impact of the new procedure. Section 4 shows preliminary results from its use within the GMAO MERRA-2 Reanalysis project. Section 5 concludes with a summary.

  17. Sustainability of algae derived biodiesel: a mass balance approach.

    PubMed

    Pfromm, Peter H; Amanor-Boadu, Vincent; Nelson, Richard

    2011-01-01

    A rigorous chemical engineering mass balance/unit operations approach is applied here to bio-diesel from algae mass culture. An equivalent of 50,000,000 gallons per year (0.006002 m3/s) of petroleum-based Number 2 fuel oil (US, diesel for compression-ignition engines, about 0.1% of annual US consumption) from oleaginous algae is the target. Methyl algaeate and ethyl algaeate diesel can according to this analysis conceptually be produced largely in a technologically sustainable way albeit at a lower available diesel yield. About 11 square miles of algae ponds would be needed with optimistic assumptions of 50 g biomass yield per day and m2 pond area. CO2 to foster algae growth should be supplied from a sustainable source such as a biomass-based ethanol production. Reliance on fossil-based CO2 from power plants or fertilizer production renders algae diesel non-sustainable in the long term. PMID:20933402

  18. Geochemical mass balances of major elements in Lake Baikal

    USGS Publications Warehouse

    Callender, E.; Granina, L.

    1997-01-01

    Major element mass balances for Lake Baikal are calculated with mostly previously published data for soluble fluxes and new, unpublished data for riverine suspended particulate matter chemistry. Physical transport seems to be the most important riverine process. The elements Ca, Mg, and Na seem to be very mobile in the weathering mantle and K and Si seem to be relatively mobile. A comparison of elemental input-output budgets and mass accumulation rates (MAR) in bottom sediments shows that most major elements, except Ca, Si, and Mn, have comparable riverine particulate matter fluxes and MARs. The addition of wet atmospheric deposition fluxes results in an excess of Ca, Mg, and Na entering the lake. The additive effect of these excess inputs during a 40-year period amounts to undetectable concentration increases in the water column. If erosion of weathered bedrock is the source of most dissolved and all particulate matter transported to the lake, theoretical elemental fluxes can be calculated with Al as the conservative element. Flux ratios (observed/theoretical) range from 0.7 to 2.2, but most fall within the acceptable range of 0.7-1.5. Major rock-forming elements are carried by rivers as weathering products and there are minimal biogeochemical processes that modify these inputs as suspended particulate matter accumulates in the bottom sediments of the lake.

  19. Nitrogen mass balances for pilot-scale biofilm stabilization ponds under tropical conditions.

    PubMed

    Babu, M A; van der Steen, N P; Hooijmans, C M; Gijzen, H J

    2011-02-01

    Nitrogen removal in biofilm waste stabilization ponds were modeled using nitrogen mass balance equations. Four pilot-scale biofilm maturation ponds were constructed in Uganda. Pond 1 was control; the others had 15 baffles in each of them. Two loading conditions were investigated (period 1, 18.2g and period 2, 26.8 g NH(4)-Nd(-1)). Total nitrogen and TKN mass balances were made. Bulk water and biofilm nitrification rates were determined and used in the TKN mass balance. Results for total nitrogen mass balance showed that for both periods, denitrification was the major removal mechanism. Nitrogen uptake by algae was more important during period 1 than in period 2. The TKN mass balance predicted well effluent TKN for period 2 than period 1. This could be due to fluctuations in algae density and ammonia uptake during period 1, no conclusions on reliability of mass balance model in period 1 was made. PMID:21183339

  20. A California Nitrogen Mass Balance: Uncertainties and information needs

    NASA Astrophysics Data System (ADS)

    Liptzin, D.; Dahlgren, R. A.

    2011-12-01

    The goal of the California Nitrogen (N) Assessment (CNA) is to evaluate the current state of N science, practice, and policy in the state of California. One component is to develop a N mass balance for the state. Because the CNA is an assessment, evaluating the data quality and quantifying uncertainty are also part of the mass balance . We estimate that a total of 1500 Gg of new reactive N is added to California every year. Of this new N, only about half of the N leaves the state while the rest is retained. The main inputs of new reactive N to California are, in order of importance: synthetic N fertilizer, fossil fuel combustion, and biological N fixation. The three largest N outputs from the state are, in order of importance, atmospheric advection, wastewater discharge to the ocean, and riverine discharge to the ocean. Approximately half of the stored N leaches to groundwater, with the other half divided between soils and vegetation, reservoirs, and urban landscapes. These N flows vary not just in magnitude, but also in the uncertainty associated with them. There was no trend in the tonnage of fertilizer sold from 1981-2001, but the 2002-2007 average has remained higher (760 Gg N) than the long-term average (520 Gg N). Bottom up calculations based on crop acreage and fertilization rates are more consistent with the 1980-2001 average suggesting a problem with the sales data. The emission of NOx from fossil fuel burning is one of the most well established flows of N. The production of ammonia and nitrous oxide from fossil fuel combustion is significantly lower than NOx, but there is less evidence to support the emissions inventories. Rates of biological N fixation are speculative with evidence more limited in natural lands than croplands. For most crops it appears that N fixation rates are strongly related to plant production, suggesting that using a single rate across large regions may be inappropriate. In addition, many studies either only measure aboveground N

  1. Micrometeorological Mass Balance Measurements of Greenhouse Gas Emissions from Composting Green-waste

    NASA Astrophysics Data System (ADS)

    Kent, E. R.; Bailey, S.; Stephens, J.; Horwath, W. R.; Paw U, K.

    2013-12-01

    Managed decomposition of organic materials is increasingly being used as an alternative waste management option and the resulting compost can be used as a fertilizer and soil amendment in home gardens and agriculture. An additional benefit is the avoidance of methane emissions associated with anaerobic decomposition in landfills. Greenhouse gases are still emitted during the composting process, but few studies have measured emissions from a full-scale windrow of composting green-waste. This study uses a micrometeorological mass balance technique (upwind and downwind vertical profile measurements of trace gas concentrations and wind velocity) to calculate emissions of carbon dioxide, methane, and nitrous oxide from a pile of composting green-waste during the dry season in Northern California. The expected source pattern was observed in measured upwind-downwind concentration differences of all three gases averaged over the study period despite substantial noise seen in the half-hourly emission calculations. Sources of uncertainty are investigated and temporal patterns analyzed. An in-situ zero-source test was conducted to examine the mass balance technique when the source of emissions was removed. Results from the micrometeorological mass balance measurements are compared with measurements taken using the more common open chamber technique.

  2. Modeling interactions between Antarctic Instability and Surface Mass Balance.

    NASA Astrophysics Data System (ADS)

    Ritz, Catherine; Agosta, Cecile; Peyaud, Vincent; Durand, Gael; Fettweis, Xavier; Favier, Vincent; Gallée, Hubert

    2015-04-01

    In the context of future global warming, Antarctic contribution to sea level rise (SLR) depends on several processes leading to opposite impacts. First, under a warming climate, precipitation is supposed to increase, inducing a plausible negative impact on SLR. Contrary to the Greenland ice sheet case, ablation should stay a marginal process at least on grounded ice. Second, oceanic warming and/or surface ponding on ice shelves may trigger a Marine Ice Sheet Instability by reducing the backforce they exert on outlet glaciers. Once engaged on such a self-entertained retreat a large positive contribution to SLR may be expected. This dynamic process is already going on in the Admundsen sea sector. Although these two processes (surface mass balance -- SMB -- and ice dynamics) have been modeled separately to infer sea level contribution, little work has been done to study their interactions. In this presentation we focus on how grounding line retreat can affect estimation of SMB in the future and the related contribution to sea level change. To evaluate the shift of precipitation pattern while the steep surface slope region migrates inward due to the grounding line retreat, we simulate surface mass balance on various surface topographies of the Antarctic ice sheet. Each ice sheet topography is obtained with an ice sheet model (GRISLI) in which grounding line retreat is parameterized according to glaciological considerations. Because we are looking at coastal changes, a high resolution is needed for the atmospheric model and here we use the regional circulation model MAR with a resolution of 40 km. The preliminary results show that the topographic change induces a shift in the precipitation pattern as high accumulation regions tend to follow the slope break at the ice sheet / shelf transition. This affects the calculation of total SMB on the grounded ice sheet (and sea level contribution) and its amplitude is related to the amplitude of the retreat. In our simulations

  3. Considerations affecting the additional weight required in mass balance of ailerons

    NASA Technical Reports Server (NTRS)

    Diehl, W S

    1937-01-01

    This paper is essentially a consideration of mass balance of ailerons from a preliminary design standpoint, in which the extra weight of the mass counterbalance is the most important phase of the problem. Equations are developed for the required balance weight for a simple aileron and this weight is correlated with the mass-balance coefficient. It is concluded the location of the c.g. of the basic aileron is of paramount importance and that complete mass balance imposes no great weight penalty if the aileron is designed to have its c.g. inherently near to the hinge axis.

  4. Fe and Cu isotope mass balances in the human body

    NASA Astrophysics Data System (ADS)

    Balter, V.; Albarede, F.; Jaouen, K.

    2011-12-01

    The ranges of the Fe and Cu isotope compositions in the human body are large, i.e. ~3% and ~2%, respectively. Both isotopic fractionations appear to be mainly controlled by redox conditions. The Fe and Cu isotope compositions of the tissues analyzed so far plot on a mixing hyperbolae between a reduced and an oxidized metals pools. The reduced metals pool is composed by erythrocytes, where Fe is bounded to hemoglobin as Fe(II) and Cu to superoxide-dismutase as Cu(I). The oxidized metals pool is composed by hepatocytes, where Fe and Cu are stored as Fe(III) ferritin and as Cu(II) ceruloplasmine, respectively. The position of each biological component in the δ56Fe-δ65Cu diagram therefore reflects the oxidation state of Fe and Cu of the predominant metal carrier protein and allows to quantify Fe and Cu fluxes between organs using mass balance calculations. For instance, serum and clot Fe and Cu isotope compositions show that current biological models of erythropoiesis violates mass conservation requirements, and suggest hidden Fe and Cu pathways during red blood cells synthesis. The results also show that a coupled Fe-Cu strong gender isotopic effect is observed in various organs. The isotopic difference between men and women is unlikely to be due to differential dietary uptake or endometrium loss, but rather reflects the effect of menstrual losses and a correlative solicitation of hepatic stores. We speculate that thorough studies of the metabolism of stable isotopes in normal conditions is a prerequisite for the understanding of the pathological dysregulations.

  5. CMB8: New software for chemical mass balance receptor modeling

    SciTech Connect

    Lewis, C.W.

    1997-12-31

    The Chemical Mass Balance (CMB) method for receptor modeling of ambient air pollutants has been in use for over two decades. over the past year the U.S. Environmental Protection Agency`s Office of Research and Development and Office of Air Quality Planning and standards have jointly sponsored the development of a new generation of CMB software, CMB8. Developmental work has been performed by the Desert Research Institute, Reno, NV. Changes embodied in CMB8 include (1) switch from a DOS-based to a Windows-based environment, (2) increased attention to volatile organic compounds (VOC) applications, (3) correction of some flaws in the previous version (CMB7), (4) more options for input and output data formats, (5) addition of a more accurate least squares computational algorithm, (6) a new treatment of source collinearity, (7) multiple defaults for sources and fitting species, and (8) choice of fitting criteria. Details of the changes and the procedure for obtaining CMB8 are given.

  6. Mass balance and composition analysis of shredder residue.

    SciTech Connect

    Pomykala, J. A., Jr.; Jody, B. J.; Spangenberger, J. S.; Daniels, E. J.; Energy Systems

    2007-01-01

    The process of shredding end-of-life vehicles to recover metals results in a byproduct commonly referred to as shredder residue. The four-and-a-half million metric tons of shredder residue produced annually in the United States is presently land filled. To meet the challenges of automotive materials recycling, the U.S. Department of Energy is supporting research at Argonne National Laboratory in cooperation with the Vehicle Recycling Partnership (VRP) of the United States Council for Automotive Research (USCAR) and the American Plastics Council. This paper presents the results of a study that was conducted by Argonne to determine variations in the composition of shredder residue from different shredders. Over 90 metric tons of shredder residues were processed through the Argonne pilot plant. The contents of the various separated streams were quantitatively analyzed to determine their composition and to identify materials that should be targeted for recovery. The analysis established a reliable mass balance for the different materials in shredder residue.

  7. Glacier crevasses: Observations, models, and mass balance implications

    NASA Astrophysics Data System (ADS)

    Colgan, William; Rajaram, Harihar; Abdalati, Waleed; McCutchan, Cheryl; Mottram, Ruth; Moussavi, Mahsa S.; Grigsby, Shane

    2016-03-01

    We review the findings of approximately 60 years of in situ and remote sensing studies of glacier crevasses, as well as the three broad classes of numerical models now employed to simulate crevasse fracture. The relatively new insight that mixed-mode fracture in local stress equilibrium, rather than downstream advection alone, can introduce nontrivial curvature to crevasse geometry may merit the reinterpretation of some key historical observation studies. In the past three decades, there have been tremendous advances in the spatial resolution of satellite imagery, as well as fully automated algorithms capable of tracking crevasse displacements between repeat images. Despite considerable advances in developing fully transient three-dimensional ice flow models over the past two decades, both the zero stress and linear elastic fracture mechanics crevasse models have remained fundamentally unchanged over this time. In the past decade, however, multidimensional and transient formulations of the continuum damage mechanics approach to simulating ice fracture have emerged. The combination of employing damage mechanics to represent slow upstream deterioration of ice strength and fracture mechanics to represent rapid failure at downstream termini holds promise for implementation in large-scale ice sheet models. Finally, given the broad interest in the sea level rise implications of recent and future cryospheric change, we provide a synthesis of 10 mechanisms by which crevasses can influence glacier mass balance.

  8. Oxalate Mass Balance During Chemical Cleaning in Tank 5F

    SciTech Connect

    Poirier, M.; Fink, S.

    2011-07-08

    The Savannah River Site (SRS) is preparing Tank 5F for closure. The first step in preparing the tank for closure is mechanical sludge removal. Following mechanical sludge removal, SRS performed chemical cleaning with oxalic acid to remove the sludge heel. Personnel are currently assessing the effectiveness of the chemical cleaning to determine whether the tank is ready for closure. SRS personnel collected liquid samples during chemical cleaning and submitted them to Savannah River National Laboratory (SRNL) for analysis. Following chemical cleaning, they collected a solid sample (also known as 'process sample') and submitted it to SRNL for analysis. The authors analyzed these samples to assess the effectiveness of the chemical cleaning process. Analysis of the anions showed the measured oxalate removed from Tank 5F to be approximately 50% of the amount added in the oxalic acid. To close the oxalate mass balance, the author collected solid samples, leached them with nitric acid, and measured the concentration of cations and anions in the leachate.

  9. Diet modification to reduce phosphorus surpluses: a mass balance approach.

    PubMed

    Maguire, R O; Crouse, D A; Hodges, S C

    2007-01-01

    Diet modification to reduce phosphorus (P) concentrations in manures has been developed in response to environmental concerns over P losses from animal agriculture to surface waters. We used USDA-NASS statistics on animal numbers and crop production to calculate county scale mass balances for manure P production, P removed in harvested portion of crops, and the potential effects of diet modification. Although spreading manure evenly over all crop acreage within a county is unlikely to occur, these calculations give a good indication as to the impact diet modification to reduce P can have at a regional or national scale. There was a high degree of regional variability in manure P surpluses (e.g., with the large crop acreages in the grain belt leading to large P offtake in crops preventing most P surpluses). In 89% of counties, there was a deficit of manure P relative to crop P removal; therefore there was a manure P surplus in 11% of counties. Diet modification decreased the percentage of states with a manure P surplus from 11 to 8%, a decrease of approximately 27%. Diet modification decreased the percentage of counties with the greatest surpluses of manure P (>30 kg ha(-1)) from 3% of all counties to 1%. Diet modification to decrease manure P is an important part of strategies to alleviate environmental concerns associated with surplus manure P in many areas, but additional strategies to deal with manure P surpluses are needed in some areas. PMID:17636283

  10. Mass and energy balance in the 1973 August 9 flare

    NASA Technical Reports Server (NTRS)

    Dere, K. P.; Cook, J. W.

    1983-01-01

    The mass and energy balance of the thermal plasma during the decay phase of the solar flare of August 9, 1973, are studied. The analysis is based on observationally determined values for the differential emission measure, density, turbulent and bulk velocities, and physical dimensions. The total particle content and total thermal energy content of the flare plasmas with temperatures above 100,000 K and their variation with time are calculated. The particle loss and the energy losses through radiation, conduction, and convection are evaluated. The decrease in total particle content can be accounted for by the convective losses through the loop footprints at 100,000 K. Radiation is the dominant energy loss mechanism although convective losses at 100,000 K can be important. Conductive losses at 100,000 K into cooler chromospheric material appear to be negligible. The decrease in the total energy content during the decay phase is equal to the sum of the energy losses over the period of observation. No requirement is found for continued heating during the decay phase.

  11. Biogeochemical phosphorus mass balance for Lake Baikal, southeastern Siberia, Russia

    USGS Publications Warehouse

    Callender, E.; Granina, L.

    1997-01-01

    Extensive data for Lake Baikal have been synthesized into a geochemical mass balance for phosphorus (P). Some of the P budget and internal cycling terms for Baikal have been compared to similar terms for oligotrophic Lake Superior, mesotrophic Lake Michigan and the Baltic Sea, and the Ocean. Lake Baikal has a large external source of fluvial P compared to the Laurentian upper Great Lakes and the Ocean. The major tributary to Lake Baikal has experienced substantial increases in organic P loading during the past 25 years. This, coupled with potential P inputs from possible phosphorite mining, may threaten Baikal's oligotrophic status in the future. Water-column remineralization of particulate organic P is substantially greater in Lake Baikal than in the Laurentian Great Lakes. This is probably due to the great water depths of Lake Baikal. There is a gradient in P burial efficiency, with very high values (80%) for Lake Baikal and Lake Superior, lower values (50%) for Lake Michigan and the Baltic Sea, and a low value (13%) for the Ocean. The accumulation rate of P in Lake Baikal sediments is somewhat greater than that in the Laurentian upper Great Lakes and the Baltic Sea, and much greater than in the Ocean. Benthic regeneration rates are surprisingly similar for large lacustrine and marine environments and supply less than 10% of the P utilized for primary production in these aquatic environments.

  12. Stable isotope mass balance of lakes: a contemporary perspective

    NASA Astrophysics Data System (ADS)

    Gibson, J. J.; Birks, S. J.; Yi, Y.

    2016-01-01

    The theoretical basis for application of stable isotope mass balance of lakes is described for a range of climatic situations including low latitude, high latitude, high altitude, continental and coastal systems, as well as cases where the atmospheric boundary layer is significantly modified by the lake evaporation process. The effects of seasonality on isotopic offset between precipitation and atmospheric vapour and the slope of the local evaporation line are described. Atmospheric feedback and its role in labelling the isotopic composition of the Laurentian Great Lakes and tropical lakes is discussed. Several important considerations are suggested to improve parameterization of quantitative paleoclimatic reconstructions including use of assumptions that are appropriate for the climatic setting, for the atmospheric feedback situation, for salinity, and headwater setting. Potential for use of dual-isotopes to trace past changes in seasonality and input, and a dual-lake index method that can potentially be used to trace connectivity of lakes are presented. In cases where modern or paleo-evaporation systems may be under-defined there are inherent limitations in the degree of quantification that can be attained.

  13. Runoff, precipitation, mass balance, and ice velocity measurements at South Cascade Glacier, Washington, 1993 balance year

    USGS Publications Warehouse

    Krimmel, R.M.

    1994-01-01

    Winter snow accumulation and summer snow, firn, and ice ablation were measured at South Cascade Glacier, Wash., to determine the winter and net balance for the 1993 balance year. The 1993 winter balance, averaged over the glacier, was 1.98 meters, and the net balance was -1.23 meters. This negative valance continued a trend of negative balance years beginning in 1977. Air temperature, barometric pressure, and runoff from this glacier basin and an adjacent non-glacierized basin were also continuously measured. Surface ice velocity was measured over an annual period. This report makes all these data available to users throughout the glaciological and climato1ogical community.

  14. North Cascade Glacier Annual Mass Balance Record Analysis 1984-2013

    NASA Astrophysics Data System (ADS)

    Pelto, M. S.

    2014-12-01

    The North Cascade Glacier Climate Project (NCGCP) was founded in 1983 to monitor 10 glaciers throughout the range and identify their response to climate change. The annual observations include mass balance, terminus behavior, glacier surface area and accumulation area ratio (AAR). Annual mass balance (Ba) measurements have been continued on the 8 original glaciers that still exist. Two glaciers have disappeared: the Lewis Glacier and Spider Glacier. In 1990, Easton Glacier and Sholes Glacier were added to the annual balance program to offset the loss. One other glacier Foss Glacier has declined to the extent that continued measurement will likely not be possible. Here we examine the 30 year long Ba time series from this project. All of the data have been reported to the World Glacier Monitoring Service (WGMS). This comparatively long record from glaciers in one region conducted by the same research program using the same methods offers some useful comparative data. Degree day factors for melt of 4.3 mm w.e.°C-1d-1 for snow and 6.6 mm w.e.°C-1d-1 for ice has been determined from 412 days of ablation observation. The variation in the AAR for equilibrium Ba is small ranging from 60 to 67. The mean annual balance of the glaciers from 1984-2013 is -0.45 ma-1, ranging from -0.31 to -0.57 ma-1 for individual glacier's. The correlation coefficient of Ba is above 0.80 between all glaciers including the USGS benchmark glacier, South Cascade Glacier. This indicates that the response is to regional climate change, not local factors. The mean annual balance of -0.45 ma-1 is close to the WGMS global average for this period -0.50 ma-1. The cumulative loss of 13.5 m w.e. and 15 m of ice thickness represents more than 20% of the volume of the glaciers.

  15. Comparison of glaciological and geodetic mass balance at Urumqi Glacier No. 1, Tian Shan, Central Asia

    NASA Astrophysics Data System (ADS)

    Wang, Puyu; Li, Zhongqin; Li, Huilin

    2016-04-01

    Glaciological and geodetic measurements are two methods to determine glacier mass balances. The mass balance of Urumqi Glacier No. 1 has been measured since 1959 by the glaciological method using ablation stakes and snowpits, except during the period 1967-1979 when the observations were interrupted. Moreover, topographic surveys have been carried out at various time intervals since the beginning of the glacier observations. Therefore, glacier volume changes are calculated by comparing topographic maps of different periods during nearly 50 years. Between 1962 and 2009, Urumqi Glacier No. 1 lost an ice volume of 29.51×106 m3, which corresponds to a cumulative ice thickness loss of 8.9 m and a mean annual loss of 0.2 m. The results are compared with glaciological mass balances over the same time intervals. The differences are 2.3%, 2.8%, 4.6%, 4.7% and 5.9% for the period 1981-86, 1986-94, 1994-2001, 2001-06 and 2006-09, respectively. For the mass balance measured with the glaciological method, the systematic errors accumulate linearly with time, whereas the errors are random for the geodetic mass balance. The geodetic balance is within the estimated error of the glaciological balance. In conclusion, the geodetic and glaciological mass balances are of high quality and therefore, there is no need to calibrate the mass balance series of Urumqi Glacier No. 1.

  16. Mass balance, meteorological, and runoff measurements at South Cascade Glacier, Washington, 1992 balance year

    USGS Publications Warehouse

    Krimmel, R.M.

    1993-01-01

    Values of winter snow accumulation and summer snow, firn, and ice ablation were measured at South Cascade Glacier, WA, to determine the winter and net balance for the 1992 balance year. The 1992 winter balance, averaged over the glacier, was 1.91 m, and the net balance was -2.01 m. This extremely negative balance continued a trend of negative balance years beginning in 1977. Air temperature (at 1,615 m and 1,867 m), barometric pressure, precipitation, and runoff from this glacier basin and an adjacent non-glacierized basin were also continuously measured. This report makes all these data, in tabular, graphical, and machine-readable forms, available to users.

  17. Chloride-Mass-Balance: Cautions in Predicting Increased Recharge Rates

    SciTech Connect

    Gee, Glendon W.; Zhang, Z. F.; Tyler , S. W.; Albright , W. H.; Singleton , M. J.

    2005-02-01

    The chloride-mass-balance (CMB) method has been used extensively to estimate recharge in arid and semi-arid environments. Required data include estimates of annual precipitation, total chloride input (from dry fallout and precipitation), and pore-water chloride concentrations. Typically, CMB has been used to estimate ancient recharge but recharge from recent land-use change has also been documented. Recharge rates below a few mm/yr are reliably detected with CMB; however, estimates above a few mm/yr appear to be less reliable. We tested the CMB method against 26 years of drainage from a 7.6 m deep lysimeter at a simulated waste-burial ground, located on the Department of Energy’s Hanford Site in southeastern Washington State, USA where land-use change has increased recharge rates. Measured drainage from the lysimeter for the past 26 years averaged 62 mm/yr. Precipitation averaged 190 mm/yr with an estimated chloride input of 0.225 mg/L. Initial pore-water chloride concentration was 88 mg/L and decreased to about 6 mg/L after 26 years, while the drainage water decreased to less than 1 mg/L. A recharge estimate made using chloride concentrations in drain water was within 20% of the measured drainage rate. In contrast, recharge estimates using 1:1 (water: soil) extracts were lower than actual by factors ranging from 2 to 8 or more. The results suggest that when recharge is above a few mm/yr, soil water extracts can lead to unreliable estimates of recharge. For conditions of elevated recharge, direct sampling of pore water is the preferred method, because chloride concentrations are often 20 to 50 times higher in directly-sampled pore water than in pore-water extracts.

  18. The formation of a clinopyroxene corona — Mass balance considerations

    NASA Astrophysics Data System (ADS)

    Zingg, Andrew J.

    1992-06-01

    The formation of a Cpx-corona is discussed from the viewpoint of continuous reaction techniques. Two cases are distinguished: a closed and open system. The first case is based on the equation eOl w + aPl u = bPl v + Opx x + cCpx y + dSpl y Plagioclase is assumed to be a solid solution between anorthite and albite (Na uCa 1-wAl 2-uSi 2+uO 8). The other minerals are solutions of their Fe- and Mg-end-members [e.g. (Mg wFe 1-w) 2SiO 4 for olivine]. Spinel forms a ternary system of hercynite-spinel-magnetite. Stoichiometric coefficients are expressed in terms of the exchange parameters t, u, v, w, x, y and z. According to stoichiometries, the net molar quantity of phaligioclase consumed equals the number of moles of clinopyroxene and spinel produced. For each mole of olivine consumed there is one mole of opx produced. A closed system is suggested by the ability to predict one of the mineral compositions in terms of the others using one of the six mass balances (Na, Ca, Mg, Fe, Al, Si) left from the calculation of five stoichiometric coefficients. This model allows the calculation of mass transfer between different shells and explains coronas from the Adirondacks, Scandinavia and the Niquelândia layered complex (Brazil). In the second case the system is open and is described by the equation. Opx x + aPl u + kCa 2+ + hSi 4+ + fFe 2+ = cCpx y + lNa + + lAl 3 + gMg 2+ The compositional variation of orthopyroxene and clinopyroxene allows the determination of c(Cpx), -(Fe 2+) and g(Mg 2+) which are interdependent. With a known value of c and assuming a constant volume of reaction the value of a may be determined. The final equation, for a plagioclase composition of XAn = 0.75, is 1 Opx + 0.35 Pl + 0.74 Ca 2+ + 0.21 Si 4+ + 0.10 Mg 2+ = 1 Cpx + 0.61 Al 3+ + 0.10 Fe 2+ + 0.09 Na + This is the reaction responsible for the formation of Cpx-coronas in the Bushveld complex.

  19. Mass balance, energy and exergy analysis of bio-oil production by fast pyrolysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mass, energy and exergy balances are analyzed for bio-oil production in a bench scale fast pyrolysis system developed by the USDA’s Agricultural Research Service (ARS) for the processing of commodity crops to fuel intermediates. Because mass balance closure is difficult to achieve due, in part, to ...

  20. Results of the Lake Michigan Mass Balance Project: Atrazine Modeling Report

    EPA Science Inventory

    This report covers an overview of chemical properties, measurements in air and water, model construct and assumptions, and results of mathematical mass balance modeling of the herbicide atrazine in the Lake Michigan basin. Within the context of the mass balance, an overview of a...

  1. A MASS BALANCE OF SURFACE WATER GENOTOXICITY IN PROVIDENCE RIVER (RHODE ISLAND USA)

    EPA Science Inventory

    White and Rasmussen (Mutation Res. 410:223-236) used a mass balance approach to demonstrate that over 85% of the total genotoxic loading to the St. Lawrence River at Montreal is non-industrial. To validate the mass balance approach and investigate the sources of genotoxins in sur...

  2. Glacier mass balance and runoff research in the U.S.A.

    USGS Publications Warehouse

    Mayo, L.R.

    1984-01-01

    Research on glacier mass balance began in the USA about 50 years ago. More complete studies of climate, snow and ice balance, and the hydrology of glaciers were initiated for the IGY in 1957 and the IHD in 1966. Investigations included the magnitude and geographic distribution of normal mass balance processes and unusual phenomena such as outbursting, accumulation of ice by freezing of water in firn, and ablation of glacier ice by volcanic activity and by calving. -from Author

  3. An Examination of Family Communication within the Core and Balance Model of Family Leisure Functioning

    ERIC Educational Resources Information Center

    Smith, Kevin M.; Freeman, Patti A.; Zabriskie, Ramon B.

    2009-01-01

    The purpose of this study was to examine family communication within the core and balance model of family leisure functioning. The study was conducted from a youth perspective of family leisure and family functioning. The sample consisted of youth (N= 95) aged 11 - 17 from 25 different states in the United States. Path analyses indicated that…

  4. Net mass balance calculations for the Shirase Drainage Basin, east Antarctica, using the mass budget method

    NASA Astrophysics Data System (ADS)

    Nakamura, Kazuki; Yamanokuchi, Tsutomu; Doi, Koichiro; Shibuya, Kazuo

    2016-06-01

    We quantify the mass budget of the Shirase drainage basin (SHI), Antarctica, by separately estimating snow accumulation (surface mass balance; SMB) and glacier ice mass discharge (IMD). We estimated the SMB in the SHI, using a regional atmospheric climate model (RACMO2.1). The SMB of the mainstream A flow region was 12.1 ± 1.5 Gt a-1 for an area of 1.985 × 105 km2. Obvious overestimation of the model round the coast, ∼0.5 Gt a-1, was corrected for. For calculating the IMD, we employed a 15-m resolution Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) with a digital elevation model (DEM) to determine the heights at the grounding line (GL), after comparison with the interpolated Bamber DEM grid heights; the results of this are referred to as the measured heights. Ice thickness data at the GL were inferred by using a free-board relationship between the measured height and the ice thickness, and considering the measured firn depth correction (4.2 m with the reference ice density of 910 kg m-3) for the nearby blue-ice area. The total IMD was estimated to be 14.0 ± 1.8 Gt a-1. Semi-empirical firn densification model gives the estimate within 0.1-0.2 Gt a-1 difference. The estimated net mass balance, -1.9 Gt a-1, has a two-σ uncertainty of ±3.3 Gt a-1, and probable melt water discharge strongly suggests negative NMB, although the associated uncertainty is large.

  5. The mass balance of the ice plain of Ice Stream B and Crary Ice Rise

    NASA Technical Reports Server (NTRS)

    Bindschadler, Robert

    1993-01-01

    The region in the mouth of Ice Stream B (the ice plain) and that in the vicinity of Crary Ice Rise are experiencing large and rapid changes. Based on velocity, ice thickness, and accumulation rate data, the patterns of net mass balance in these regions were calculated. Net mass balance, or the rate of ice thickness change, was calculated as the residual of all mass fluxes into and out of subregions (or boxes). Net mass balance provides a measure of the state of health of the ice sheet and clues to the current dynamics.

  6. Surface mass balance reanalysis of Taku and Lemon Creek glaciers, Alaska: 1946-2015

    NASA Astrophysics Data System (ADS)

    McNeil, Christopher

    We reanalyzed geodetic and glaciological surface mass balance records of Taku and Lemon Creek glaciers for the period 1946--2015 to determine what has driven the contradictory behavior of these glaciers. During the past century, Taku Glacier has been increasing in area and mass, while Lemon Creek Glacier has simultaneously shrunk in area and mass. Between 1948 and 1999 geodetic mass balance rates are +0.33+/-0.34 m w.e. a--1 for Taku Glacier and 0.61+/-0.34 m w.e. a--1 for Lemon Creek Glacier. Geodetic mass balance rates decreased to +0.01+/-0.23 m w.e. a--1 and --0.65 +/-0.23 m w.e. a--1 for Taku and Lemon Creek glaciers respectively, between 1999 and 2013. We updated the glaciological analysis of annual field data, and found no significant difference between updated and previous annual mass balance solutions (p--value < 0.001). We used the geodetic mass balance to calibrate annual glaciological estimates between 1946 and 2015, removing systematic biases of +0.06 m w.e. a--1 from the Taku Glacier record and --0.06 m w.e. a --1 from the Lemon Creek Glacier record. Comparing mass balance anomalies we determined inter--annual variability of surface mass balance is the same for Taku and Lemon Creek glaciers. However, differences in glacier specific hypsometry and mass balance profile drive systematic differences in both annual and long--term glacier mass balance rates.

  7. Modeling the mass balance of the Wolverine Glacier Alaska USA using the PTAA model

    NASA Astrophysics Data System (ADS)

    Korn, D.

    2010-12-01

    Glaciers in Alaska have been increasingly losing mass over the last several decades. This trend is especially apparent in South-Central Alaska where many glaciers are undergoing rapid changes and contributing substantially to rising sea levels (Arendt et al., 2002). It is important to understand the rates at which these glaciers are losing mass as well as the important climatic drivers to better prepare for what the future holds in this region and the rest of the world. This work compares glacier mass balance data modeled through the Precipitation-Temperature Area Altitude (PTAA) mass balance model for the Wolverine Glacier in the Kenai Peninsula in South-Central Alaska to observed data from the USGS “benchmark” glacier program in order to help validate the model. The mass balance data are also correlated with climate data in order to understand the main climatic drivers of the glacier mass balance in this region.

  8. Glacier modeling in support of field observations of mass balance at South Cascade Glacier, Washington, USA

    USGS Publications Warehouse

    Josberger, Edward G.; Bidlake, William R.

    2010-01-01

    The long-term USGS measurement and reporting of mass balance at South Cascade Glacier was assisted in balance years 2006 and 2007 by a new mass balance model. The model incorporates a temperature-index melt computation and accumulation is modeled from glacier air temperature and gaged precipitation at a remote site. Mass balance modeling was used with glaciological measurements to estimate dates and magnitudes of critical mass balance phenomena. In support of the modeling, a detailed analysis was made of the "glacier cooling effect" that reduces summer air temperature near the ice surface as compared to that predicted on the basis of a spatially uniform temperature lapse rate. The analysis was based on several years of data from measurements of near-surface air temperature on the glacier. The 2006 and 2007 winter balances of South Cascade Glacier, computed with this new, model-augmented methodology, were 2.61 and 3.41 mWE, respectively. The 2006 and 2007 summer balances were -4.20 and -3.63 mWE, respectively, and the 2006 and 2007 net balances were -1.59 and -0.22 mWE. PDF version of a presentation on the mass balance of South Cascade Glacier in Washington state. Presented at the American Geophysical Union Fall Meeting 2010.

  9. Modeling Past and Future Surface Mass Balance of the Patagonian Icefields

    NASA Astrophysics Data System (ADS)

    Schaefer, M.; Casassa, G., Sr.; Machguth, H.; Falvey, M. J.

    2014-12-01

    We present surface mass balance simulations of the Patagonian Icefield that were driven by global climate data (reanalysis/GCM) which were downscaled using the regional climate model Weather Research and Forecasting (WRF) and statistical downscaling methods. The special climatic situation in the region with sharp climate gradients introduced by the blocking of the westerlies by the high peaks of the Icefield are reproduced by downscaled climatic data. The mass balance simulations were validated and interpreted using geodetic mass balances, measured point balances and a complete velocity field of the Southern Patagonia Icefield (SPI) from spring 2004. The high measured accumulation of snow as well as the high measured ablation values are reproduced by the model. Subtracting the modeled surface mass balance from the geodetic balances, calving fluxes of major outlet glaciers were inferred. Good agreement with calving fluxes estimated from velocity data was obtained in many cases however on several glaciers the inferred calving fluxes seem to overestimate the measured calving fluxes. The measured calving fluxes exhibit large uncertainties due to mostly unknown ice thickness data and evolution of glacier velocities through time. The accumulation of snow and its redistribution due to wind drift present the mayor uncertainties in the modeled surface mass balance. Assuming no substantial changes in ice flow, the surface mass balance model driven by ECHAM5 data in the A1B scenario predicts a contribution of the Patagonian Icefields to sea-level rise in the 21st century of 7.3 mm.

  10. Annual and seasonal mass balances of Chhota Shigri Glacier (benchmark glacier, Western Himalaya), India

    NASA Astrophysics Data System (ADS)

    Mandal, Arindan; Ramanathan, Alagappan; Farooq Azam, Mohd; Wagnon, Patrick; Vincent, Christian; Linda, Anurag; Sharma, Parmanand; Angchuk, Thupstan; Bahadur Singh, Virendra; Pottakkal, Jose George; Kumar, Naveen; Soheb, Mohd

    2015-04-01

    Several studies on Himalayan glaciers have been recently initiated as they are of particular interest in terms of future water supply, regional climate change and sea-level rise. In 2002, a long-term monitoring program was initiated on Chhota Shigri Glacier (15.7 square km, 9 km long, 6263-4050 m a.s.l.) located in Lahaul and Spiti Valley, Himachal Pradesh, India. This glacier lies in the monsoon-arid transition zone (western Himalaya) and is a representative glacier in Lahaul and Spiti Valley. While annual mass balances have been measured continuously since 2002 using the glaciological method, seasonal scale observations began in 2009. The annual and seasonal mass balances were then analyzed along with meteorological conditions in order to understand the role of winter and summer balances on annual glacier-wide mass balance of Chhota Shigri glacier. During the period 2002-2013, the glacier experienced a negative glacier-wide mass balance of -0.59±0.40 m w.e. a-1 with a cumulative glaciological mass balance of -6.45 m w.e. Annual glacier-wide mass balances were negative except for four years (2004/05, 2008/09, 2009/10 and 2010/11) where it was generally close to balanced conditions. Equilibrium line altitude (ELA) for steady state condition is calculated as 4950 m a.s.l. corresponding to an accumulation area ratio (AAR) of 62% using annual glacier-wide mass balance, ELA and AAR data between 2002 and 2013. The winter glacier-wide mass balance between 2009 and 2013 ranges from a maximum value of 1.38 m w.e. in 2009/10 to a minimum value of 0.89 in 2012/13 year whereas the summer glacier-wide mass balance varies from the highest value of -0.95 m w.e. in 2010/11 to the lowest value of -1.72 m w.e. in 2011/12 year. The mean vertical mass balance gradient between 2002 and 2013 was 0.66 m w.e. (100 m)-1 quite similar to Alps, Nepalese Himalayas etc. Over debris covered area, the gradients are highly variable with a negative mean value of -2.15 m w.e. (100 m)-1 over 2002

  11. Mass-Balance Fluctuations of Glaciers in the Pacific Northwest and Alaska, USA

    NASA Astrophysics Data System (ADS)

    Josberger, E. G.; Bidlake, W. R.; March, R. S.; Kennedy, B. W.

    2006-12-01

    The mass balance of mid-latitude glaciers of the Pacific Northwest and southern Alaska fluctuates in response to changes in the regional and global atmospheric climate. More than 40 years of net and seasonal mass balance records by the U.S. Geological Survey for South Cascade Glacier, Washington, and Wolverine and Gulkana Glaciers, Alaska, show annual and inter-annual fluctuations that reflect the controlling climatic conditions. South Cascade and Wolverine Glaciers are strongly affected by the warm and wet maritime climate of the Northeast Pacific Ocean, and the winter balances are strongly related to the Pacific Decadal Oscillations (PDO). Gulkana Glacier is more isolated from maritime influences and the net balance variation is more closely linked to the summer balance. By the late 1970's, mass-balance records for the three were long enough to reflect the 1976-77 shift in PDO from negative to positive. Both maritime glaciers responded, with net balance of South Cascade Glacier becoming consistently negative and that of Wolverine Glacier becoming predominantly positive. The overall trend of negative mass balance continued through 2004 for South Cascade Glacier, where the 1977 to 2004 cumulative net balance was about -22 meters water equivalent (mweq). After a gain of about 7 mweq, the trend of positive net balance for Wolverine Glacier ended in 1989. Beginning in 1989, the net balance trend for Wolverine Glacier became predominantly negative and the cumulative net balance for 1989 to 2004 was about -14 mweq. Net balance of Gulkana Glacier did not respond appreciably to the 1976-77 PDO shift. The cumulative net balance for Gulkana Glacier from the beginning of the record (1966) through 1988 was about -3 mweq. The major change in trend of mass balance occurred in 1989, when net balance became almost exclusively negative. The cumulative net balance during 1989 through 2004 was about 13 mweq. As a result trends in net balance had become strongly negative for more

  12. Re-establishing seasonal mass balance observation at Abramov Glacier, Kyrgyzstan, from 1968 - 2012

    NASA Astrophysics Data System (ADS)

    Barandun, Martina; Huss, Matthias; Azisov, Erlan; Gafurov, Abror; Hoelzle, Martin; Merkushkin, Aleksandr; Salzmann, Nadine; Usubaliev, Ryskul

    2013-04-01

    The Abramov Glacier, located in the Pamir Alay in Kyrgyzstan, was subject to intense studies in the frame of various scientific programs under the former USSR. With the breakdown of the Soviet Union, the monitoring was abruptly abandoned in the late nineties. Well documented and continuous seasonal mass balance observations are available for 1968-1994. However, some inconsistencies between different publications lead to in-homogeneous data sets. Recently, the project CATCOS (Capacity Building and Twinning for Climate Observing Systems) was launched, aiming among other goals to re-establish mass balance observation on selected glaciers in Kyrgyzstan. At Abramov Glacier, a new stake network, an automatic weather station (AWS) and two automatic terrestrial cameras with instantaneous data transfer over satellite were installed in 2011. Measurements were repeated and intensified in 2012 and will be subject of a third field campaign in summer 2013. A complete re-analysis of the long-term mass balance series from 1968 to 1994 delivers corrected mass balance data for Abramov Glacier. To homogenize in-situ mass balance records, a spatially distributed mass balance model driven with local daily temperature and precipitation data was calibrated to each seasonal mass balance survey. The model resolves seasonal mass-balance measurements to a daily timescale and performs spatial inter- and extrapolation of data points based on a consistent algorithm, taking into account the principal factors of mass balance distribution. Summarizing the annually optimized parameters over the entire study period provides a robust model parameter set for years with less extensive direct measurements. From 1994 to 2011, neither direct point measurements nor meteorological data are available. In order to run the calibrated model developed for the 1960's to 90's, climate input variables were taken from bias corrected Re-analysis data (NCEP/NCAR and JRA). Evaluation of the model results was achieved

  13. A possible change in mass balance of Greenland and Antarctic ice sheets in the coming century

    SciTech Connect

    Ohmura, A.; Wild, M.; Bengtsson, L.

    1996-09-01

    A high-resolution GCM is found to simulate precipitation and surface energy balance of high latitudes with high accuracy. This opens new possibilities to investigate the future mass balance of polar glaciers and its effect on sea level. The surface mass balance of the Greenland and the Antarctic ice sheets is simulated using the ECHAM3 GCM with T106 horizontal resolution. With this model, two 5-year integrations for the present and doubled carbon dioxide conditions based on the boundary conditions provided by the ECHAM1/T21 transient to what extent the effect of climate change on the mass balance on the two largest glaciers of the world can differ. On Greenland one sees a slight decrease in accumulation and a substantial increase in melt, while on Antarctica a large increase in accumulation without melt is projected. Translating the mass balances into terms of sea-level equivalent, the Greenland discharge causes a sea level rise of 1.1 mm yr{sup {minus}1}, while the accumulation on Antarctica tends to lower it by 0.9 mm yr{sup {minus}1}. The change in the combined mass balance of the two continents is almost zero. The sea level change of the next century can be affected more effectively by the thermal expansion of seawater and the mass balance of smaller glaciers outside of Greenland and Antarctica. 24 refs., 11 figs., 2 tabs.

  14. Global application of a surface mass balance model using gridded climate data

    NASA Astrophysics Data System (ADS)

    Giesen, R. H.; Oerlemans, J.

    2012-04-01

    Global applications of surface mass balance models have large uncertainties, as a result of poor climate input data and limited availability of mass balance measurements. This study addresses several possible consequences of these limitations for the modelled mass balance. This is done by applying a simple surface mass balance model that only requires air temperature and precipitation as input data, to glaciers in different regions. In contrast to other models used in global applications, this model separately calculates the contributions of net solar radiation and the temperature-dependent fluxes to the energy balance. We derive a relation for these temperature-dependent fluxes using automatic weather station (AWS) measurements from glaciers in different climates. With local, hourly input data, the model is well able to simulate the observed seasonal variations in the surface energy and mass balance at the AWS sites. Replacing the hourly local data by monthly gridded climate data removes summer snowfall and winter melt events and hence influences the modelled mass balance most on locations with a small seasonal temperature cycle. Representative values for the multiplication factor and vertical gradient of precipitation are determined by fitting modelled winter mass balance profiles to observations on 80 glaciers in different regions. For 72 of the 80 glaciers, the precipitation provided by the climate data set has to be multiplied with a factor above unity; the median factor is 2.55. The vertical precipitation gradient ranges from negative to positive values, with more positive values for maritime glaciers and a median value of 1.5 mm a-1 m. With calibrated precipitation, the modelled annual mass balance gradient closely resembles the observations on the 80 glaciers, the absolute values are matched by adjusting either the incoming solar radiation, the temperature-dependent flux or the air temperature. The mass balance sensitivity to changes in temperature is

  15. Calibration of a surface mass balance model for global-scale applications

    NASA Astrophysics Data System (ADS)

    Giesen, R. H.; Oerlemans, J.

    2012-12-01

    Global applications of surface mass balance models have large uncertainties, as a result of poor climate input data and limited availability of mass balance measurements. This study addresses several possible consequences of these limitations for the modelled mass balance. This is done by applying a simple surface mass balance model that only requires air temperature and precipitation as input data, to glaciers in different regions. In contrast to other models used in global applications, this model separately calculates the contributions of net solar radiation and the temperature-dependent fluxes to the energy balance. We derive a relation for these temperature-dependent fluxes using automatic weather station (AWS) measurements from glaciers in different climates. With local, hourly input data, the model is well able to simulate the observed seasonal variations in the surface energy and mass balance at the AWS sites. Replacing the hourly local data by monthly gridded climate data removes summer snowfall and winter melt events and, hence, influences the modelled mass balance most on locations with a small seasonal temperature cycle. Modelled winter mass balance profiles are fitted to observations on 82 glaciers in different regions to determine representative values for the multiplication factor and vertical gradient of precipitation. For 75 of the 82 glaciers, the precipitation provided by the climate dataset has to be multiplied with a factor above unity; the median factor is 2.5. The vertical precipitation gradient ranges from negative to positive values, with more positive values for maritime glaciers and a median value of 1.5 mm a-1 m-1. With calibrated precipitation, the modelled annual mass balance gradient closely resembles the observations on the 82 glaciers, the absolute values are matched by adjusting either the incoming solar radiation, the temperature-dependent flux or the air temperature. The mass balance sensitivity to changes in temperature is

  16. BALANCE

    DOEpatents

    Carmichael, H.

    1953-01-01

    A torsional-type analytical balance designed to arrive at its equilibrium point more quickly than previous balances is described. In order to prevent external heat sources creating air currents inside the balance casing that would reiard the attainment of equilibrium conditions, a relatively thick casing shaped as an inverted U is placed over the load support arms and the balance beam. This casing is of a metal of good thernnal conductivity characteristics, such as copper or aluminum, in order that heat applied to one portion of the balance is quickly conducted to all other sensitive areas, thus effectively preventing the fornnation of air currents caused by unequal heating of the balance.

  17. Tree-ring based mass balance estimates along the North Pacific Rim

    NASA Astrophysics Data System (ADS)

    Malcomb, N.; Wiles, G. C.

    2009-12-01

    Glacier mass balance reconstructions provide a means of placing short-term mass balance observations into a longer-term context. In western North America, most instrumental records of mass balance are limited in duration and capture only a narrow window of glacial behavior over an interval that is dominated by warming and ablation. Tree-ring series from northwestern North America are used to reconstruct annual mass balance for Gulkana and Wolverine Glaciers in Alaska, Peyto and Place Glaciers in British Columbia, and South Cascade and Blue Glaciers in Washington State. Mass balance models rely on the temperature and precipitation sensitivity of the tree-ring chronologies and mass balance records, as well as teleconnections along the North Pacific sector. The reconstructions extend through the latter portions of the Little Ice Age (LIA) and highlight the role of decadal and secular-scale climate change in forcing mass balance. Net mass balance reconstructions are broadly consistent with the moraine record that coincides with two major intervals of positive mass balance and with cooling related to the Maunder and Dalton solar minima. Secular warming in the later portions of the 19th and the 20th centuries corresponds with a pronounced interval of negative mass balance, and model instability after 1980. These trends show that the marked changes in glacier systems over recent decades throughout the Northwestern Cordillera are unique for the last several centuries and furthermore, suggest that modest gains forced by increasing precipitation over the latter 20th century in coastal settings are not sufficient to force glacier expansion or moraine building. Reconstructed (blue) and instrumental (red) net mass balances, Northern Hemisphere Temperature anomalies (Wilson et al., 2007), and PDO index (MacDonald and Case, 2005). A= Gulkana Glacier, B=Wolverine Glacier, C=Peyto Glacier, D=Place Glacier, E=South Cascade, F=Blue Glacier, G=PDO index, and H=Northern Hemisphere

  18. Spent Nuclear Fuel (SNF) Project Multi Canister Overpack (MCO) Process Flow Diagram Mass Balance Calculations

    SciTech Connect

    KLEM, M.J.

    2000-09-08

    The purpose of this calculation document is to develop the bases for the material balances of the Multi-Canister Overpack (MCO) Level 1 Process Flow Diagram (PFD). The attached mass balances support revision two of the PFD for the MCO and provide future reference.

  19. Mass-balance approach for assessing nitrate flux intidal wetlands -- lessons learned

    EPA Science Inventory

    Field experiments were carried out in 2010 and 2011 to assess the nitrate balance in a small tidal slough located in the Yaquina Estuary, Oregon. In 2010 we used a whole-slough, mass-balance approach, while a smaller scale, flume-like experiment in a tidal channel with a dense ...

  20. Spent Nuclear Fuel (SNF) Project Canister Storage Building (CSB) Process Flow Diagram Mass Balance Calculations

    SciTech Connect

    KLEM, M.J.

    2000-05-11

    The purpose of these calculations is to develop the material balances for documentation of the Canister Storage Building (CSB) Process Flow Diagram (PFD) and future reference. The attached mass balances were prepared to support revision two of the PFD for the CSB. The calculations refer to diagram H-2-825869.

  1. Mercury mass balance in Lake Michigan--the knowns and unknowns

    EPA Science Inventory

    LM2-Mercury, a mercury mass balance model, was developed to simulate and evaluate the transport, fate, and biogeochemical transformations of mercury in Lake Michigan. The model simulates total suspended solids (TSS), disolved organic carbon (DOC), and total, elemental, divalent, ...

  2. A GIS TECHNIQUE FOR ESTIMATING NATURAL ATTENUATION RATES AND MASS BALANCES: JOURNAL ARTICLE

    EPA Science Inventory

    NRMRL-ADA-01308 Durant, ND, Srinivasan, P, Faust, CR, Burnell, DK, Klein, KL, and Burden*, D.S. A GIS Technique for Estimating Natural Attenuation Rates and Mass Balances. Battelle's Sixth International ...

  3. Composition of Meridiani Hematite-rich Spherules: A Mass-Balance Mixing-Model Approach

    NASA Astrophysics Data System (ADS)

    Jolliff, B. L.; Athena Science Team

    2005-03-01

    A mass-balance model using APXS data and microscopic images indicates that the composition of spherules ("blueberries"), found at the Meridiani site by the Mars Exploration Rover Opportunity and thought to be concretions, contain ~45-60 wt% hematite.

  4. Distributed modeling of snow cover mass and energy balance in the Rheraya watershed (High Atlas, Morocco)

    NASA Astrophysics Data System (ADS)

    Marchane, Ahmed; Gascoin, Simon; Jarlan, Lionel; Hanich, Lahoucine

    2016-04-01

    The mountains of the High Moroccan Atlas represent an important source of water for the neighboring arid plains. Despite the importance of snow in the regional water balance, few studies were devoted to the modeling of the snow cover at the watershed scale. This type of modeling is necessary to characterize the contribution of snowmelt to water balance and understanding its sensitivity to natural and human-induced climate fluctuations. In this study, we applied a spatially-distributed model of the snowpack evolution (SnowModel, Liston & Elder 2006) on the Rheraya watershed (225 km²) in the High Atlas in order to simulate the mass and energy balance of the snow cover and the evolution of snow depth over a full season (2008-2009). The model was forced by 6 meteorological stations. The model was evaluated locally at the Oukaimeden meteorological station (3230 m asl) where snow depth is recorded continuously. To evaluate the model at the watershed scale we used the daily MODIS snow cover products and a series of 15 cloud-free optical images acquired by the FORMOSAT-2 satellite at 8-m resolution from February to June 2009. The results showed that the model is able to simulate the snow depth in the Oukaimeden station for the 2008-2009 season, and also to simulate the spatial and temporal variation of of the snow cover area in the watershed Rheraya. Based on the model output we examine the importance of the snow sublimation on the water balance at the watershed scale.

  5. Mass-balance modelling of Chhota Shigri and Patsio glacier in western Himalaya, India

    NASA Astrophysics Data System (ADS)

    Engelhardt, Markus; Kumar, Pankaj; Li, Lu; Ramanathan, Alagappan

    2016-04-01

    Projections of glacier mass-balance evolution in the Himalayas are afflicted with high uncertainty due to the diversity of the climatic conditions and the extremes in topographical relief. Large spatial variations in glacier mass balances are connected with the diverse precipitation patterns. While there are indications of recent glacier retreats in the Himalayas, only few glaciers have been monitored over long periods. In 2002, a long term continuous monitoring programme of glacier mass balance was started on Chhota Shigri glacier (15.7 km²). During the period 2002-2013, measurements show an average glacier-wide mass balance of -0.59±0.12 m w.e. after near zero annual mass balances in the 1990s. On Patsio glacier (2.3 km²) mass-balance studies were initiated in 2010. We apply a mass-balance model for the glaciers Chhota Shigri and Patsio using gridded data from two different regional climate models: 1) the Weather Research and Forecasting (WRF) Model for the period 1970-2005 (on 50 km resolution) and 1996-2005 (on 3 km resolution), and 2) the regional climate model REMO for the period and 1989-2013 (25 km resolution). The data are downscaled from its grid resolution to the glacier grid (300 m). Additional input are daily potential global radiation values, calculated using a digital elevation model (DEM) at a resolution of 30 m and considering slope, aspect and shading of the surrounding topography. The mass-balance model calculates snow accumulation, melt and runoff on a sub-daily (hourly) time scale. Calibration and validation data are the available seasonal and annual mass-balance measurements together with point measurements of temperature, precipitation and radiation. Results show that this region of the Himalayas is situated in the transition zone between areas where the annual glacier mass balance ba is controlled by summer temperature and areas where ba is controlled by winter precipitation. In addition, summer snowfalls are a major influencing factor on

  6. Determination of Interannual to Decadal Changes in Ice Sheet Mass Balance from Satellite Altimetry

    NASA Technical Reports Server (NTRS)

    Zwally, H. Jay; Busalacchi, Antonioa J. (Technical Monitor)

    2001-01-01

    A major uncertainty in predicting sea level rise is the sensitivity of ice sheet mass balance to climate change, as well as the uncertainty in present mass balance. Since the annual water exchange is about 8 mm of global sea level equivalent, the +/- 25% uncertainty in current mass balance corresponds to +/- 2 mm/yr in sea level change. Furthermore, estimates of the sensitivity of the mass balance to temperature change range from perhaps as much as - 10% to + 10% per K. Although the overall ice mass balance and seasonal and inter-annual variations can be derived from time-series of ice surface elevations from satellite altimetry, satellite radar altimeters have been limited in spatial coverage and elevation accuracy. Nevertheless, new data analysis shows mixed patterns of ice elevation increases and decreases that are significant in terms of regional-scale mass balances. In addition, observed seasonal and interannual variations in elevation demonstrate the potential for relating the variability in mass balance to changes in precipitation, temperature, and melting. From 2001, NASA's ICESat laser altimeter mission will provide significantly better elevation accuracy and spatial coverage to 86 deg latitude and to the margins of the ice sheets. During 3 to 5 years of ICESat-1 operation, an estimate of the overall ice sheet mass balance and sea level contribution will be obtained. The importance of continued ice monitoring after the first ICESat is illustrated by the variability in the area of Greenland surface melt observed over 17-years and its correlation with temperature. In addition, measurement of ice sheet changes, along with measurements of sea level change by a series of ocean altimeters, should enable direct detection of ice level and global sea level correlations.

  7. Low resolution optical remote sensing applied to the monitoring of seasonal glacier mass balance.

    NASA Astrophysics Data System (ADS)

    Drolon, Vanessa; Maisongrande, Philippe; Berthier, Etienne; Swinnen, Else

    2015-04-01

    Mass balance is a key variable to describe the state of health of glaciers, their contribution to sea level rise and, in a few dry regions, their role in water resource. We explore here a new method to retrieve seasonal glacier mass balances from low resolution optical remote sensing. We derive winter and summer snow maps for each year during 1998-2014, using the Normalized Difference Snow Index (NDSI) computed from visible and SWIR channels available with SPOT/VEGETATION. The NDSI dynamic is directly linked to the area percentage of snow in the VGT kilometric pixel. The combination of 15 years of 10-daily NDSI maps with the SRTM DEM allows us to calculate the altitude of the transition between bare soil and snow. Then, we compare the interannual dynamic of this altitude with in situ measurements of mass balance available for 60 alpine glaciers (Huss et al., 2010; Zemp et al., 2009, 2013) and find promising relationships for winter mass balance. We also explore the possibility of a real-time monitoring of winter mass balance for a selection of alpine glaciers. Finally, we discuss the robustness and genericity of these relationships for their future application in regions where in situ glaciers mass balances are scarce or not available.

  8. Mass and thermal energy balance of potato processing operations

    SciTech Connect

    Chadbourne, D.L.; Heldman, D.R.

    1981-01-01

    A mass and thermal energy analysis was conducted for a potato peeling operation. Results provide insight into opportunities for process modifications leading to increased recovery of product components and thermal energy.

  9. Re-analysing eleven years of mass balance observations at Langenferner, Ortler-Cevedale Group, Italy

    NASA Astrophysics Data System (ADS)

    Galos, Stephan; Klug, Christoph; Rieg, Lorenzo; Sauter, Tobias; Gurgiser, Wolfgang; Kaser, Georg

    2016-04-01

    Long term surface mass balance records of glaciers are of peculiar scientific interest as they reflect the most direct link between the observed glacier changes and the underlying atmospheric forcing. Consequently they provide a unique source of information which is used in a wide range of different models (climate-, mass- or energy balance-, sea level rise- or run-off models). However, both inhomogeneities and unknown error ranges in the observational series limit the usefulness of respective datasets. Hence, the homogenization of long term records, as well as the availability of solid error values can significantly improve the quality of data and is therefore of crucial interest to the community. The surface mass balance of Langenferner / Vedretta Lunga, a small valley glacier in the Italian Eastern Alps, has been measured since the hydrological year 2003/04. The resulting series of annual mass balances was homogenized using a process based mass balance model in order to calculate the annual mass balance for points without stake measurements during the first observation years. A detailed error analysis was performed considering all significant sources of uncertainties involved in the mass balance determination applying the direct glaciological method. The homogenized mass balance values differ from the initial series mainly during the first measurement years when the number of measurements in the upper glacier parts was low and consequently large errors in the spatial extrapolation of measurements were made due to a lack of knowledge about changes in the upper glacier part. Hence the largest errors in mass balance calculation at Langenferner / Vedretta Lunga originate from inaccurate spatial extrapolation of point measurements, while other effects such as errors due to surface roughness play a role on the point scale but are canceled out by the high number of measurement points on the glacier wide scale. A comparison of the surface mass balance to the geodetic

  10. Modeling the surface mass balance and firn evolution of glaciers around Kongsfjorden, Svalbard

    NASA Astrophysics Data System (ADS)

    Kohler, J.; van Pelt, W. J. J.

    2014-12-01

    A coupled modeling approach is applied to simulate the long-term (1961-2012) surface mass balance and subsurface evolution of the Kongsvegen and Holtedahlfonna glacier systems in western Svalbard. Principle aims are: 1) to quantify and analyze the distributed surface mass balance evolution, 2) to estimate the contribution of melt water refreezing and internal accumulation to the mass balance, and 3) to detect changes in firn conditions over the simulation period. In order to achieve this, HIRLAM regional climate model output for 1961-2012 is projected onto the 100-m model grid and serves as input for a coupled model surface energy balance - firn model. Available stake measurements since 1987, together with weather station data and snow profiling observations, are used for parameter estimation, as well as validation of the model results. Extensive spin-up is performed to provide initialized subsurface conditions at the start of the experiments. Results indicate a slightly positive area-averaged surface mass balance of 0.08 m w.e. yr-1, which only fractionally compensates for mass loss by calving. Melt water refreezing (spatial mean 0.30 m w.e. yr-1) provides a strong buffer for mass loss, whereas substantial internal accumulation (up to 0.22 m w.e. yr-1) adds uncertainty to mass balance observations in the accumulation zone. An increasingly negative surface mass balance over the last two decades has led to a retreat of the firn line and a substantial reduction of the firn air content. Together with a negative trend in the albedo and elevated runoff this could mark the onset of accelerated near-future mass loss.

  11. Preliminary Examination of the Supply and Demand Balance for Renewable Electricity

    SciTech Connect

    Swezey, B.; Aabakken, J.; Bird, L.

    2007-10-01

    In recent years, the demand for renewable electricity has accelerated as a consequence of state and federal policies and the growth of voluntary green power purchase markets, along with the generally improving economics of renewable energy development. This paper reports on a preliminary examination of the supply and demand balance for renewable electricity in the United States, with a focus on renewable energy projects that meet the generally accepted definition of "new" for voluntary market purposes, i.e., projects installed on or after January 1, 1997. After estimating current supply and demand, this paper presents projections of the supply and demand balance out to 2010 and describe a number of key market uncertainties.

  12. Understanding the Role of Wind in Reducing the Surface Mass Balance Estimates over East Antarctica

    NASA Astrophysics Data System (ADS)

    Das, I.; Scambos, T. A.; Koenig, L.; Creyts, T. T.; Bell, R. E.; van den Broeke, M. R.; Lenaerts, J.; Paden, J. D.

    2014-12-01

    Accurate quantification of surface snow-accumulation over Antarctica is important for mass balance estimates and climate studies based on ice core records. An improved estimate of surface mass balance must include the significant role near-surface wind plays in the sublimation and redistribution of snow across Antarctica. We have developed an empirical model based on airborne radar and lidar observations, and modeled surface mass balance and wind fields to produce a continent-wide prediction of wind-scour zones over Antarctica. These zones have zero to negative surface mass balance, are located over locally steep ice sheet areas (>0.002) and controlled by bedrock topography. The near-surface winds accelerate over these zones, eroding and sublimating the surface snow. This scouring results in numerous localized regions (≤ 200 km2) with reduced surface accumulation. Each year, tens of gigatons of snow on the Antarctic ice sheet are ablated by persistent near-surface katabatic winds over these wind-scour zones. Large uncertainties remain in the surface mass balance estimates over East Antarctica as climate models do not adequately represent the small-scale physical processes that lead to mass loss through sublimation or redistribution over the wind-scour zones. In this study, we integrate Operation IceBridge's snow radar over the Recovery Ice Stream with a series of ice core dielectric and depth-density profiles for improved surface mass balance estimates that reflect the mass loss over the wind-scour zones. Accurate surface mass balance estimates from snow radars require spatially variable depth-density profiles. Using an ensemble of firn cores, MODIS-derived surface snow grain size, modeled accumulation rates and surface temperatures from RACMO2, we assemble spatially variable depth-density profiles and use our mapping of snow density variations to estimate layer mass and net accumulation rates from snow radar layer data. Our study improves the quantification of

  13. Using GRACE measurements of time variable gravity, elevation changes from ICESat, OIB and ENVISAT and surface mass balance outputs from RACMO to improve ice mass balance estimates

    NASA Astrophysics Data System (ADS)

    Sutterley, T. C.; Velicogna, I.; Csatho, B. M.; van den Broeke, M. R.; Wahr, J. M.; Flament, T.; Rezvan-Behbahani, S.; Babonis, G. S.; A, G.

    2013-12-01

    The glacial isostatic adjustment (GIA) correction 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 and Antarctic GIA corrections by comparing the spatial patterns of GRACE-derived ice mass trends corrected for glacial isostatic adjustment with volume changes from ICESat (Ice, Cloud, and Land Elevation Satellite), OIB (Operation IceBridge) and ENVISAT altimetry missions, and surface mass balance (SMB) products from the Regional Atmospheric Climate Model (RACMO). We show that using the spatial and temporal characteristics of the different contributions to the ice mass balance estimates that it is possible to evaluate different GIA corrections. In Greenland, the GRACE ice mass changes obtained using the Simpson et al. (2009) and Geruo et al. (2013) GIA corrections show good agreement in the spatial patterns and amplitude. The GRACE estimate corrected using the Wu et al. (2010) GIA shows similar spatial patterns to the other two, but produces an average ice mass loss for the entire ice sheet that is 50% smaller. In Antarctica, the total magnitude and spatial structure of the GRACE-estimated ice mass change is highly dependent on the GIA correction. In key basins of East Antarctica, the interpretation of regional ice mass changes can reflect the GIA model selection as the ice mass to GIA signal ratio is smaller. We apply the same methodology used for the Greenland ice sheet in Antarctica to evaluate the different GIA corrections and check for consistency between the different techniques at a regional scale.

  14. Glacier mass-balance fluctuations in the Pacific Northwest and Alaska, USA

    NASA Astrophysics Data System (ADS)

    Josberger, Edward G.; Bidlake, William R.; March, Rod S.; Kennedy, Ben W.

    2007-10-01

    The more than 40 year record of net and seasonal mass-balance records from measurements made by the United States Geological Survey on South Cascade Glacier, Washington, and Wolverine and Gulkana Glaciers, Alaska, shows annual and interannual fluctuations that reflect changes in the controlling climatic conditions at regional and global scales. As the mass-balance record grows in length, it is revealing significant changes in previously described glacier mass-balance behavior, and both inter-glacier and glacier-climate relationships. South Cascade and Wolverine Glaciers are strongly affected by the warm and wet maritime climate of the northeast Pacific Ocean. Their net balances have generally been controlled by winter accumulation, with fluctuations that are strongly related to the Pacific Decadal Oscillation (PDO). Recently, warm dry summers have begun to dominate the net balance of the two maritime glaciers, with a weakening of the correlation between the winter balance fluctuations and the PDO. Non-synchronous periods of positive and negative net balance for each glacier prior to 1989 were followed by a 1989-2004 period of synchronous and almost exclusively negative net balances that averaged -0.8 m for the three glaciers.

  15. Glacier mass-balance fluctuations in the Pacific Northwest and Alaska, USA

    USGS Publications Warehouse

    Josberger, E.G.; Bidlake, W.R.; March, R.S.; Kennedy, B.W.

    2007-01-01

    The more than 40 year record of net and seasonal mass-balance records from measurements made by the United States Geological Survey on South Cascade Glacier, Washington, and Wolverine and Gulkana Glaciers, Alaska, shows annual and interannual fluctuations that reflect changes in the controlling climatic conditions at regional and global scales. As the mass-balance record grows in length, it is revealing significant changes in previously described glacier mass-balance behavior, and both inter-glacier and glacier-climate relationships. South Cascade and Wolverine Glaciers are strongly affected by the warm and wet maritime climate of the northeast Pacific Ocean. Their net balances have generally been controlled by winter accumulation, with fluctuations that are strongly related to the Pacific Decadal Oscillation (PDO). Recently, warm dry summers have begun to dominate the net balance of the two maritime glaciers, with a weakening of the correlation between the winter balance fluctuations and the PDO. Non-synchronous periods of positive and negative net balance for each glacier prior to 1989 were followed by a 1989-2004 period of synchronous and almost exclusively negative net balances that averaged -0.8 m for the three glaciers.

  16. Recalculated mass balance record for Midre Lovénbreen, Svalbard

    NASA Astrophysics Data System (ADS)

    Kohler, J.

    2013-12-01

    Glacier mass balance has been measured since 1968 on Midre Lovénbreen, Svalbard, one of the longest high Arctic records. Available data includes areally-averaged winter, summer, and net balances. Balances by elevation, however, were not consistently reported. Here we derive a time-series of the balances as a function of elevation using original stake data from archived field notebooks and maps, graphs of balance as a function of elevation taken from old reports. We recalculate areally-averaged balances using a different fits to the data, rather than hand-drawn curves from earlier years, and adjust for changes in hypsometry. There is good agreement between in situ mass balance and geodetic changes obtained by differencing digital elevation models (DEMs) from different dates (1936, 1962, 1969, 1977, 1995, 2003, 2005). The main long-term trends over the length of the 44-yr record are that winter and net balance are decreasing overall, and that summer and net balance elevational gradients increase, the result of increasing ice loss at lower elevations.

  17. Comparison of geodetic and glaciological mass-balance techniques, Gulkana Glacier, Alaska, U.S.A

    USGS Publications Warehouse

    Cox, L.H.; March, R.S.

    2004-01-01

    The net mass balance on Gulkana Glacier, Alaska, U.S.A., has been measured since 1966 by the glaciological method, in which seasonal balances are measured at three index sites and extrapolated over large areas of the glacier. Systematic errors can accumulate linearly with time in this method. Therefore, the geodetic balance, in which errors are less time-dependent, was calculated for comparison with the glaciological method. Digital elevation models of the glacier in 1974, 1993 and 1999 were prepared using aerial photographs, and geodetic balances were computed, giving - 6.0??0.7 m w.e. from 1974 to 1993 and - 11.8??0.7 m w.e. from 1974 to 1999. These balances are compared with the glaciological balances over the same intervals, which were - 5.8??0.9 and -11.2??1.0 m w.e. respectively; both balances show that the thinning rate tripled in the 1990s. These cumulative balances differ by <6%. For this close agreement, the glaciologically measured mass balance of Gulkana Glacier must be largely free of systematic errors and be based on a time-variable area-altitude distribution, and the photography used in the geodetic method must have enough contrast to enable accurate photogrammetry.

  18. Compact Sensitive Piezoelectric Mass Balance for Measurement of Unconsolidated Materials in Space

    NASA Technical Reports Server (NTRS)

    Sherrit, Stewart; Trebi-Ollennu, Ashitey; Bonitz, Robert; Bar-Cohen, Yoseph; Yen, Jesse T.

    2010-01-01

    In many in-situ instruments information about the mass of the sample could aid in the interpretation of the data and portioning instruments might require an accurate sizing of the sample mass before dispensing the sample. In addition, on potential sample return missions a method to directly assess the captured sample size would be required to determine if the sampler could return or needs to continue attempting to acquire sample. In an effort to meet these requirements piezoelectric balances were developed using flextensional actuators which are capable of monitoring the mass using two methods. A piezoelectric balance could be used to measure mass directly by monitoring the voltage developed across the piezoelectric which is linear with force, or it could be used in resonance to produce a frequency change proportional to the mass change. In this case of the latter, the piezoelectric actuator/balance would be swept in frequency through its fundamental resonance. If a mass is added to the balance the resonance frequency would shift down proportionally to the mass. By monitoring the frequency shift the mass could be determined. This design would allow for two independent measurements of the mass. In microgravity environments spacecraft thrusters could be used to provide acceleration in order to produce the required force for the first technique or to bring the mass into contact with the balance in the second approach. In addition, the measuring actuators, if driven at higher voltages, could be used to fluidize the powder to aid sample movement. In this paper, we outline some of our design considerations and present the results of a few prototype balances that we have developed.

  19. Glaciological and geodetic mass balance of ten long-term glaciers in Norway

    NASA Astrophysics Data System (ADS)

    Andreassen, L. M.; Elvehøy, H.; Kjøllmoen, B.; Engeset, R. V.

    2015-11-01

    The glaciological and geodetic methods provide independent observations of glacier mass balance. The glaciological method measures the surface mass balance, on a seasonal or annual basis, whereas the geodetic method measures surface, internal and basal mass balances, over a period of years or decades. In this paper, we reanalyse the 10 glaciers with long-term mass balance series in Norway. The reanalysis includes (i) homogenisation of both glaciological and geodetic observation series, (ii) uncertainty assessment, (iii) estimates of generic differences including estimates of internal and basal melt, (iv) validation, and (v) partly calibration of mass balance series. This study comprises an extensive set of data (454 mass balance years, 34 geodetic surveys and large volumes of supporting data, such as metadata and field notes). In total, 21 periods of data were compared and the results show discrepancies between the glaciological and geodetic methods for some glaciers, which in part are attributed to internal and basal ablation and in part to inhomogeneity in the data processing. Deviations were smaller than 0.2 m w.e. a-1 for 12 out of 21 periods. Calibration was applied to seven out of 21 periods, as the deviations were larger than the uncertainty. The reanalysed glaciological series shows a more consistent signal of glacier change over the period of observations than previously reported: six glaciers had a significant mass loss (14-22 m w.e.) and four glaciers were nearly in balance. All glaciers have lost mass after year 2000. More research is needed on the sources of uncertainty, to reduce uncertainties and adjust the observation programmes accordingly. The study confirms the value of carrying out independent high-quality geodetic surveys to check and correct field observations.

  20. Reanalysis of long-term series of glaciological and geodetic mass balance for 10 Norwegian glaciers

    NASA Astrophysics Data System (ADS)

    Andreassen, Liss M.; Elvehøy, Hallgeir; Kjøllmoen, Bjarne; Engeset, Rune V.

    2016-03-01

    Glaciological and geodetic methods provide independent observations of glacier mass balance. The glaciological method measures the surface mass balance, on a seasonal or annual basis, whereas the geodetic method measures surface, internal, and basal mass balances, over a period of years or decades. In this paper, we reanalyse the 10 glaciers with long-term mass-balance series in Norway. The reanalysis includes (i) homogenisation of both glaciological and geodetic observation series, (ii) uncertainty assessment, (iii) estimates of generic differences including estimates of internal and basal melt, (iv) validation, and, if needed, (v) calibration of mass-balance series. This study comprises an extensive set of data (484 mass-balance years, 34 geodetic surveys, and large volumes of supporting data, such as metadata and field notes). In total, 21 periods of data were compared and the results show discrepancies between the glaciological and geodetic methods for some glaciers, which are attributed in part to internal and basal ablation and in part to inhomogeneity in the data processing. Deviations were smaller than 0.2 m w.e. a-1 for 12 out of 21 periods. Calibration was applied to 7 out of 21 periods, as the deviations were larger than the uncertainty. The reanalysed glaciological series shows a more consistent signal of glacier change over the period of observations than previously reported: six glaciers had a significant mass loss (14-22 m w.e.) and four glaciers were nearly in balance. All glaciers have lost mass after the year 2000. More research is needed on the sources of uncertainty to reduce uncertainties and adjust the observation programmes accordingly. The study confirms the value of carrying out independent high-quality geodetic surveys to check and correct field observations.

  1. Understanding Recent Mass Balance Changes of the Greenland Ice Sheet

    NASA Technical Reports Server (NTRS)

    vanderVeen, Cornelius

    2003-01-01

    The ultimate goal of this project is to better understand the current transfer of mass between the Greenland Ice Sheet, the world's oceans and the atmosphere, and to identify processes controlling the rate of this transfer, to be able to predict with greater confidence future contributions to global sea level rise. During the first year of this project, we focused on establishing longer-term records of change of selected outlet glaciers, reevaluation of mass input to the ice sheet and analysis of climate records derived from ice cores, and modeling meltwater production and runoff from the margins of the ice sheet.

  2. A LEGO Watt balance: An apparatus to determine a mass based on the new SI

    NASA Astrophysics Data System (ADS)

    Chao, L. S.; Schlamminger, S.; Newell, D. B.; Pratt, J. R.; Seifert, F.; Zhang, X.; Sineriz, G.; Liu, M.; Haddad, D.

    2015-11-01

    A global effort to redefine our International System of Units (SI) is underway, and the change to the new system is expected to occur in 2018. Within the newly redefined SI, the present base units will still exist but be derived from fixed numerical values of seven reference constants. In particular, the unit of mass (the kilogram) will be realized through a fixed value of the Planck constant h. A so-called watt balance, for example, can then be used to realize the kilogram unit of mass within a few parts in 108. Such a balance has been designed and constructed at the National Institute of Standards and Technology. For educational outreach and to demonstrate the principle, we have constructed a LEGO tabletop watt balance capable of measuring a gram-level masses to 1% relative uncertainty. This article presents the design, construction, and performance of the LEGO watt balance and its ability to determine h.

  3. Insight into glacier climate interaction: reconstruction of the mass balance field using ice extent data

    NASA Astrophysics Data System (ADS)

    Visnjevic, Vjeran; Herman, Frédéric; Licul, Aleksandar

    2016-04-01

    With the end of the Last Glacial Maximum (LGM), about 20 000 years ago, ended the most recent long-lasting cold phase in Earth's history. We recently developed a model that describes large-scale erosion and its response to climate and dynamical changes with the application to the Alps for the LGM period. Here we will present an inverse approach we have recently developed to infer the LGM mass balance from known ice extent data, focusing on a glacier or ice cap. The ice flow model is developed using the shallow ice approximation and the developed codes are accelerated using GPUs capabilities. The mass balance field is the constrained variable defined by the balance rate β and the equilibrium line altitude (ELA), where c is the cutoff value: b = max(βṡ(S(z) - ELA), c) We show that such a mass balance can be constrained from the observed past ice extent and ice thickness. We are also investigating several different geostatistical methods to constrain spatially variable mass balance, and derive uncertainties on each of the mass balance parameters.

  4. Surface energy budget and mass balance of Zhadang Glacier in the central Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Li, B.; Acharya, K.; Yu, Z.; Su, F.; liang, Z.

    2011-12-01

    It is difficult to clearly investigate the surface energy budget and glacier evolution under the changed climate environments, especially on accounts of limited data set. We attempted to calculate the summer mass balance of Zhadang Glacier (5710 m above sea level), located in the central Tibetan Plateau. This small and high-altitude glacier has been retreating during the previous decades. Energy balance was calculated on a 30 m square grid on the glacier for the summer periods in 2007 and 2008. On average, net radiation contributed more than 96% of the energy gain while only less than 4% was supplied by the sensible heat flux. Most energy loss on the glacier was contributed by the turbulent heat fluxes and only roughly 30% of the total energy was available for melting. A large deficit and a surplus summer mass balance were obtained for years 2006/07 and 2007/08, respectively. The switch in mass balance from negative to positive in the summer of 2008 is caused by early precipitation (mostly snow) resulting in low temperature on the glacier. Low temperature produces less energy that contributes to melting, whereas increased snow accumulation produces higher surface albedo reflecting away incoming solar radiation. The high sensitivity of air temperature may imply that the low temperature was more important than the increased precipitation in the mass balance switch in Zhadang Glacier. Despite a continuous negative mass balance for several decades in Zhadang Glacier 2008 may have brought a temporary relief.

  5. Mass-balance measurements in Alaska and suggestions for simplified observation programs

    USGS Publications Warehouse

    Trabant, D.C.; March, R.S.

    1999-01-01

    US Geological Survey glacier fieldwork in Alaska includes repetitious measurements, corrections for leaning or bending stakes, an ability to reliably measure seasonal snow as deep as 10 m, absolute identification of summer surfaces in the accumulation area, and annual evaluation of internal accumulation, internal ablation, and glacier-thickness changes. Prescribed field measurement and note-taking techniques help eliminate field errors and expedite the interpretative process. In the office, field notes are transferred to computerized spread-sheets for analysis, release on the World Wide Web, and archival storage. The spreadsheets have error traps to help eliminate note-taking and transcription errors. Rigorous error analysis ends when mass-balance measurements are extrapolated and integrated with area to determine glacier and basin mass balances. Unassessable errors in the glacier and basin mass-balance data reduce the value of the data set for correlations with climate change indices. The minimum glacier mass-balance program has at least three measurement sites on a glacier and the measurements must include the seasonal components of mass balance as well as the annual balance.

  6. Modelling The Energy And Mass Balance Of A Black Glacier

    NASA Astrophysics Data System (ADS)

    Grossi, G.; Taschner, S.; Ranzi, R.

    A distributed energy balance hydrologic model has been implemented to simulate the melting season of the Belvedere glacier, situated in the Anza river basin (North- Western Italy) for a few years. The Belvedere Glacier is an example of SblackS glacier, ´ since the ablation zone is covered by a significant debris layer. The glacierSs termi- nus has an altitude of 1785 m asl which is very unusual for the Southern side of the European Alps. The model accounts for the energy exchange processes at the inter- face between the atmospheric boundary layer and the snow/ice/debris layer. To run the model hydrometeorological and physiographic data were collected, including the depth of the debris cover and the tritium (3H) concentration in the glacial river. Mea- surements of the soil thermal conductivity were carried out during a field campaign organised within the glaciers monitoring GLIMS project, at the time of the passage of the Landsat and the Terra satellites last 15 August 2001. A comparison of the different energy terms simulated by the model assigns a dominant role to the shortwave radia- tion, which provides the highest positive contribution to the energy available for snow- and ice-melt, while the sensible heat turns out to be the second major source of heat. Longwave radiation balance and latent heat seem to be less relevant and often nega- tive. The role of the debris cover is not negligible, since its thermal insulation causes, on average, a decrease in the ice melt volume. One of the model variables is the tem- perature of the debris cover, which can be a useful information when a black glacier is to be monitored through remote sensing techniques. The visible and near infrared radi- ation data do not always provide sufficient information to detect the glaciers' margins beneath the debris layer. For this reason the information of the different thermal sur- face characteristics (pure ice, debris covered ice, rock), proved by the energy balance model results was

  7. A high-resolution record of Greenland mass balance

    NASA Astrophysics Data System (ADS)

    McMillan, Malcolm; Leeson, Amber; Shepherd, Andrew; Briggs, Kate; Armitage, Thomas W. K.; Hogg, Anna; Kuipers Munneke, Peter; Broeke, Michiel; Noël, Brice; Berg, Willem Jan; Ligtenberg, Stefan; Horwath, Martin; Groh, Andreas; Muir, Alan; Gilbert, Lin

    2016-07-01

    We map recent Greenland Ice Sheet elevation change at high spatial (5 km) and temporal (monthly) resolution using CryoSat-2 altimetry. After correcting for the impact of changing snowpack properties associated with unprecedented surface melting in 2012, we find good agreement (3 cm/yr bias) with airborne measurements. With the aid of regional climate and firn modeling, we compute high spatial and temporal resolution records of Greenland mass evolution, which correlate (R = 0.96) with monthly satellite gravimetry and reveal glacier dynamic imbalance. During 2011-2014, Greenland mass loss averaged 269 ± 51 Gt/yr. Atmospherically driven losses were widespread, with surface melt variability driving large fluctuations in the annual mass deficit. Terminus regions of five dynamically thinning glaciers, which constitute less than 1% of Greenland's area, contributed more than 12% of the net ice loss. This high-resolution record demonstrates that mass deficits extending over small spatial and temporal scales have made a relatively large contribution to recent ice sheet imbalance.

  8. Using a biocultural approach to examine migration/globalization, diet quality, and energy balance.

    PubMed

    Himmelgreen, David A; Cantor, Allison; Arias, Sara; Romero Daza, Nancy

    2014-07-01

    The aim of this paper is to examine the role and impact that globalization and migration (e.g., intra-/intercontinental, urban/rural, and circular) have had on diet patterns, diet quality, and energy balance as reported on in the literature during the last 20 years. Published literature from the fields of anthropology, public health, nutrition, and other disciplines (e.g., economics) was collected and reviewed. In addition, case studies from the authors' own research are presented in order to elaborate on key points and dietary trends identified in the literature. While this review is not intended to be comprehensive, the findings suggest that the effects of migration and globalization on diet quality and energy balance are neither lineal nor direct, and that the role of social and physical environments, culture, social organization, and technology must be taken into account to better understand this relationship. Moreover, concepts such as acculturation and the nutrition transition do not necessarily explain or adequately describe all of the global processes that shape diet quality and energy balance. Theories from nutritional anthropology and critical bio-cultural medical anthropology are used to tease out some of these complex interrelationships. PMID:24463063

  9. Changes of the Arctic Ice Caps from ICESat and GRACE - A study of mass balance.

    NASA Astrophysics Data System (ADS)

    Nilsson, Johan; Sandberg Sørensen, Louise; Barletta, Valentina Roberta; Forsberg, René

    2013-04-01

    Data from ICESat, compared with GRACE data, were used to estimate the mass balance of the smaller Arctic ice caps on Svalbard, Iceland and the Canadian Arctic from the years 2003-2009. In this study we used the repeat track method to estimate the surface elevation change of the Arctic ice caps from ICESat altimetry. The GRACE mass balance was obtained using a point mass modeling method, which allowed a better separation of the dominant signal from the Greenland Ice Sheet. In the ICESat part of the study we used several different methods for estimating the mass balance. The methods where based on both interpolation and extrapolation of the elevation change estimates over the ice caps, using both parametric and non-parametric approaches. We found that all Arctic ice caps show a consistent negative mass balance from the year 2003-2009. Ranging from -3 to -26 Gt/yr from the ICESat estimates for the different regions, which is in good agreement with the GRACE results. Also found is that the choice of method used for the ICESat analysis can have a significant impact on the mass balance.

  10. A 3-axis force balanced accelerometer using a single proof-mass

    SciTech Connect

    Lemkin, M.A.; Boser, B.E.; Auslander, D.; Smith, J.

    1997-04-01

    This paper presents a new method for wideband force balancing a proof-mass in multiple axes simultaneously. Capacitive position sense and force feedback are accomplished using the same air-gap capacitors through time multiplexing. Proof of concept is experimentally demonstrated with a single-mass monolithic surface micromachined 3-axis accelerometer.

  11. The mass balance approach: application to interpreting the chemical evolution of hydrologic systems.

    USGS Publications Warehouse

    Plummer, L.N.; Back, W.

    1980-01-01

    Mass balance calculations are applied to observed chemical and isotopic data of three natural water systems involving carbonate reactions in order to define mineral stoichiometry of reactants and products, relative rates of reactions, and mass transfer. One study evaluates reactions in a lagoon on the east coast of the Yucatan Peninsula, Mexico.- from Authors

  12. Mass Balance. Operational Control Tests for Wastewater Treatment Facilities. Instructor's Manual [and] Student Workbook.

    ERIC Educational Resources Information Center

    Carnegie, John W.

    This module describes the process used to determine solids mass and location throughout a waste water treatment plant, explains how these values are used to determine the solids mass balance around single treatment units and the entire system, and presents calculations of solids in pounds and sludge units. The instructor's manual contains a…

  13. Comparison of direct and geodetic mass balances on a multi-annual time scale

    NASA Astrophysics Data System (ADS)

    Fischer, A.

    2010-07-01

    Glacier mass balance is measured with the direct or the geodetic method. In this study, the geodetic mass balances of six Austrian glaciers in 19 periods between 1953 and 2006 are compared to the direct mass balances in the same periods. The mean annual geodetic mass balance for all periods is -0.5 m w.e./year. The mean difference between the geodetic and the direct data is -0.7 m w.e., the minimum -7.3 m w.e. and the maximum 5.6 m w.e. The accuracy of geodetic mass balance resulting from the accuracy of the DEMs ranges from 2 m w.e. for photogrammetric data to 0.002 m w.e. for LIDAR data. Basal melt, seasonal snow cover and density changes of the surface layer contribute up to 0.7 m w.e. for the period of 10 years to the difference to the direct method. The characteristics of published data of Griesgletscher, Gulkana Glacier, Lemon Creek glacier, South Cascade, Storbreen, Storglaciären, and Zongo Glacier is similar to these Austrian glaciers. For 26 analyzed periods with an average length of 18 years the mean difference between the geodetic and the direct data is -0.4 m w.e., the minimum -7.2 m w.e. and the maximum 3.6 m w.e. Longer periods between the acquisition of the DEMs do not necessarily result in a higher accuracy of the geodetic mass balance. Specific glaciers show specific trends of the difference between the direct and the geodetic data according to their type and state. In conclusion, geodetic and direct mass balance data are complementary, but differ systematically.

  14. Mass balances on selected polycyclic aromatic hydrocarbons in the New York-New Jersey Harbor.

    PubMed

    Rodenburg, Lisa A; Valle, Sandra N; Panero, Marta A; Muñoz, Gabriela R; Shor, Leslie M

    2010-01-01

    Mass balances on 10 polycyclic aromatic hydrocarbons (PAHs) in the New York-New Jersey Harbor (hereafter "the Harbor") were constructed using monitoring data from the water column, sediment, and atmosphere. Inputs considered included tributaries, atmospheric deposition, wastewater treatment plant discharges, combined sewer overflows (CSOs), and stormwater runoff. Removal processes examined included tidal exchange between the Harbor and the coastal Bight and Long Island Sound, volatilization, and accumulation or burial of sediment-bound PAHs in the Harbor. The PAHs investigated were fluorene, phenanthrene, fluoranthene, pyrene, benz[a]anthracene, benzo[a]pyrene, perylene, benzo[ghi]perylene, indeno[1,2,3-cd]pyrene, and dibenz[a,h]anthracene. The results show inputs and outputs are fairly well balanced for most compounds, a finding that suggests aerobic biodegradation may not be a key loss process in this Harbor, as has been assumed in other systems. The main pathway for inputs of all PAHs is stormwater runoff. Atmospheric deposition is an important conveyor of PAHs with molecular weights < or =202 g mol(-1). A principal objective of this report is to expose key data gaps, which include the need for comprehensive monitoring of both flow and PAH concentrations in stormwater and CSOs. An improved understanding of the key transmission routes of nonpoint source pollutants is essential for sustainable management of urban water resources. PMID:20176837

  15. Uncertainty in Modeling Dust Mass Balance and Radiative Forcing from Size Parameterization

    SciTech Connect

    Zhao, Chun; Chen, Siyu; Leung, Lai-Yung R.; Qian, Yun; Kok, Jasper; Zaveri, Rahul A.; Huang, J.

    2013-11-05

    This study examines the uncertainties in simulating mass balance and radiative forcing of mineral dust due to biases in the aerosol size parameterization. Simulations are conducted quasi-globally (180oW-180oE and 60oS-70oN) using the WRF24 Chem model with three different approaches to represent aerosol size distribution (8-bin, 4-bin, and 3-mode). The biases in the 3-mode or 4-bin approaches against a relatively more accurate 8-bin approach in simulating dust mass balance and radiative forcing are identified. Compared to the 8-bin approach, the 4-bin approach simulates similar but coarser size distributions of dust particles in the atmosphere, while the 3-mode pproach retains more fine dust particles but fewer coarse dust particles due to its prescribed og of each mode. Although the 3-mode approach yields up to 10 days longer dust mass lifetime over the remote oceanic regions than the 8-bin approach, the three size approaches produce similar dust mass lifetime (3.2 days to 3.5 days) on quasi-global average, reflecting that the global dust mass lifetime is mainly determined by the dust mass lifetime near the dust source regions. With the same global dust emission (~6000 Tg yr-1), the 8-bin approach produces a dust mass loading of 39 Tg, while the 4-bin and 3-mode approaches produce 3% (40.2 Tg) and 25% (49.1 Tg) higher dust mass loading, respectively. The difference in dust mass loading between the 8-bin approach and the 4-bin or 3-mode approaches has large spatial variations, with generally smaller relative difference (<10%) near the surface over the dust source regions. The three size approaches also result in significantly different dry and wet deposition fluxes and number concentrations of dust. The difference in dust aerosol optical depth (AOD) (a factor of 3) among the three size approaches is much larger than their difference (25%) in dust mass loading. Compared to the 8-bin approach, the 4-bin approach yields stronger dust absorptivity, while the 3-mode

  16. Present and future mass standards for the LNE watt balance and the future dissemination of the mass unit in France

    NASA Astrophysics Data System (ADS)

    Pinot, Patrick; Beaudoux, Florian; Bentouati, Djilali; Espel, Patrick; Madec, Tanguy; Thomas, Matthieu; Silvestri, Zaccari; Ziane, Djamel; Piquemal, François

    2016-08-01

    The value of the Planck constant h was determined in 2014 by means of the LNE watt balance experiment. The relative standard uncertainty was 31 parts in 108. This first determination was performed in air with a 500 g mass standard made from XSH Alacrite. The main uncertainty components in air associated with the mass involve the calibration, the mass stability, the buoyancy correction and the magnetic interaction correction. The combined relative uncertainty due to the mass is 7.2 parts in 108. The use in 2016 of a mass standard made from platinum iridium alloy significantly reduces the component of uncertainty arising from the mass standard for a Planck constant measurement either in air or under vacuum. The relative uncertainty due to this contribution is estimated to be about 3 parts in 108 in air and one part in 108 under vacuum. The future system for the dissemination of the mass unit using the LNE watt balance will be based on a primary realization with three 500 g mass standards made from platinum–iridium alloy, pure iridium and Udimet 720 respectively, coupled with a pool of kilograms made from different materials. Pure iridium and Udimet 720 are new materials to make reference mass standards proposed by CNAM and LNE respectively and have never been used by any NMI for manufacturing mass standards until now. Some new results concerning their surface behavior are given.

  17. Uncertainty in alpine snow mass balance simulations due to snow model parameterisation and windflow representation

    NASA Astrophysics Data System (ADS)

    Musselman, K. N.; Pomeroy, J. W.; Essery, R.; Leroux, N.

    2013-12-01

    Despite advances in alpine snow modelling there remain two fundamental areas of divergent scientific thought in estimating alpine snow mass balances: i) blowing snow sublimation losses, and ii) wind flow representation. Sublimation calculations have poorly understood humidity feedbacks that vary considerably and mathematical representations of alpine windflow vary in complexity - these differences introduce uncertainty. To better estimate and restrain this uncertainty, a variety of physically based, spatially distributed snowmelt models that consider the physics of wind redistribution and sublimation of blowing snow were evaluated for their ability to simulate seasonal snow distribution and melt patterns in a windy alpine environment in the Canadian Rockies. The primary difference in the snow models was their calculation of blowing snow sublimation losses which ranged from large to small estimates. To examine the uncertainty introduced by windflow calculations on the snow model simulations, each model was forced with output from windflow models of varying computational complexity and physical realism from a terrain-based empirical interpolation of station observations to a simple turbulence model to a computational fluid dynamics model that solves for the Navier-Stokes equations. The high-resolution snow simulations were run over a 1 km2 spatial extent centred on a ridgetop meteorological station within the Marmot Creek Research basin, Alberta, Canada. The three windflow simulations all produced reasonable results compared to wind speeds measured on two opposing slopes (bias better than ×0.3 m s-1; RMSE < 1.1 m s-1), however there was great sensitivity in SWE simulated by the snow models to the driving windflow simulation used. Specifically, there were distinct differences in the magnitude and location of snow drifts from all snow models that depended on the windflow scheme. When compared to measurements from airborne LiDAR, snow surveys, and automated snow depth

  18. Biogeochemical mass balances in a turbid tropical reservoir. Field data and modelling approach

    NASA Astrophysics Data System (ADS)

    Phuong Doan, Thuy Kim; Némery, Julien; Gratiot, Nicolas; Schmid, Martin

    2014-05-01

    The turbid tropical Cointzio reservoir, located in the Trans Mexican Volcanic Belt (TMVB), behaves as a warm monomictic water body (area = 6 km2, capacity 66 Mm3, residence time ~ 1 year). It is strategic for the drinking water supply of the city of Morelia, capital of the state of Michoacán, and for downstream irrigation during the dry season. This reservoir is a perfect example of a human-impacted system since its watershed is mainly composed of degraded volcanic soils and is subjected to high erosion processes and agricultural loss. The reservoir is threatened by sediment accumulation and nutrients originating from untreated waters in the upstream watershed. The high content of very fine clay particles and the lack of water treatment plants lead to serious episodes of eutrophication (up to 70 μg chl. a L-1), high levels of turbidity (Secchi depth < 30 cm) and a long period of anoxia (from May to October). Based on intensive field measurements in 2009 (deposited sediment, benthic chamber, water vertical profiles, reservoir inflow and outflow) we determined suspended sediment (SS), carbon (C), nitrogen (N) and phosphorus (P) mass balances. Watershed SS yields were estimated at 35 t km2 y-1 of which 89-92 % were trapped in the Cointzio reservoir. As a consequence the reservoir has already lost 25 % of its initial storage capacity since its construction in 1940. Nutrient mass balances showed that 50 % and 46 % of incoming P and N were retained by sedimentation, and mainly eliminated through denitrification respectively. Removal of C by 30 % was also observed both by sedimentation and through gas emission. To complete field data analyses we examined the ability of vertical one dimensional (1DV) numerical models (Aquasim biogeochemical model coupled with k-ɛ mixing model) to reproduce the main biogeochemical cycles in the Cointzio reservoir. The model can describe all the mineralization processes both in the water column and in the sediment. The values of the

  19. A balanced scorecard approach in assessing IT value in healthcare sector: an empirical examination.

    PubMed

    Wu, Ing-Long; Kuo, Yi-Zu

    2012-12-01

    Healthcare sector indicates human-based and knowledge-intensive property. Massive IT investments are necessary to maintain competitiveness in this sector. The justification of IT investments is the major concern of senior management. Empirical studies examining IT value have found inconclusive results with little or no improvement in productivity. Little research has been conducted in healthcare sector. The balanced scorecard (BSC) strikes a balance between financial and non-financial measure and has been applied in evaluating organization-based performance. Moreover, healthcare organizations often consider their performance goal at customer satisfaction in addition to financial performance. This research thus proposed a new hierarchical structure for the BSC with placing both finance and customer at the top, internal process at the next, and learning and growth at the bottom. Empirical examination has found the importance of the new BSC structure in assessing IT investments. Learning and growth plays the initial driver for reaching both customer and financial performance through the mediator of internal process. This can provide deep insight into effectively managing IT resources in the hospitals. PMID:22366918

  20. Estimates of Ice Sheet Mass Balance from Satellite Altimetry: Past and Future

    NASA Technical Reports Server (NTRS)

    Zwally, H. Jay; Zukor, Dorothy J. (Technical Monitor)

    2001-01-01

    A major uncertainty in predicting sea level rise is the sensitivity of ice sheet mass balance to climate change, as well as the uncertainty in present mass balance. Since the annual water exchange is about 8 mm of global sea level equivalent, the 20% uncertainty in current mass balance corresponds to 1.6 mm/yr in sea level change. Furthermore, estimates of the sensitivity of the mass balance to temperature change range from perhaps as much as - 10% to + 10% per K. A principal purpose of obtaining ice sheet elevation changes from satellite altimetry has been estimation of the current ice sheet mass balance. Limited information on ice sheet elevation change and their implications about mass balance have been reported by several investigators from radar altimetry (Seasat, Geosat, ERS-1&2). Analysis of ERS-1&2 data over Greenland for 7 years from 1992 to 1999 shows mixed patterns of ice elevation increases and decreases that are significant in terms of regional-scale mass balances. Observed seasonal and interannual variations in ice surface elevation are larger than previously expected because of seasonal and interannUal variations in precipitation, melting, and firn compaction. In the accumulation zone, the variations in firn compaction are modeled as a function of temperature leaving variations in precipitation and the mass balance trend. Significant interannual variations in elevation in some locations, in particular the difference in trends from 1992 to 1995 compared to 1995 to 1999, can be explained by changes in precipitation over Greenland. Over the 7 years, trends in elevation are mostly positive at higher elevations and negative at lower elevations. In addition, trends for the winter seasons (from a trend analysis through the average winter elevations) are more positive than the corresponding trends for the summer. At lower elevations, the 7-year trends in some locations are strongly negative for summer and near zero or slightly positive for winter. These

  1. Global Trends and Variability In the Mass Balance of Mountain and Valley Glaciers

    NASA Astrophysics Data System (ADS)

    Medwedeff, W. G.; Roe, G.

    2015-12-01

    Glacier mass balance (i.e., accumulation and ablation) is the most direct connection between climate and glaciers. We perform a comprehensive evaluation of the available global network of mass-balance measurements, with a particular interest given to mountain and valley glaciers. Each mass-balance time series is decomposed into a trend and the variability about that trend. Observed variability ranges by an order of magnitude, depending on climate setting (i.e., maritime vs. continental). For the great majority of glaciers, variability is well characterized by normally distributed, random fluctuations that are uncorrelated between seasons, or in subsequent years. The magnitude of variability for both summer and winter is well correlated with mean wintertime balance, which reflects the climatic setting. Collectively, summertime variability exceeds wintertime variability, except for maritime glaciers. Trends in annual mass balance are generally negative, driven primarily by summertime changes. Approximately 25% of annual-mean records show statistically significant negative trends when judged in isolation. In aggregate, the global trend is negative and significant. We further evaluate the magnitude of trends relative to the variability. We find that, on average, trends are approximately -0.2 standard deviations per decade, although there is a broad spread among individual glaciers. Finally, for two long records we also compare mass-balance trends and variability with nearby meteorological stations. We find significant differences among stations meaning caution is warranted in interpreting any point measurement (such as mass balance) as representative of region-wide behavior. By placing observed trends in the context of natural variability, the results are useful for interpreting past glacial history, and for placing constraints on future predictability.

  2. Trends and variability in the global dataset of glacier mass balance

    NASA Astrophysics Data System (ADS)

    Medwedeff, William G.; Roe, Gerard H.

    2016-06-01

    Glacier mass balance (i.e., accumulation and ablation) is the most direct connection between climate and glaciers. We perform a comprehensive evaluation of the available global network of mass-balance measurements. Each mass-balance time series is decomposed into a trend and the variability about that trend. Observed variability ranges by an order of magnitude, depending on climate setting (i.e., maritime vs continental). For the great majority of glaciers, variability is well characterized by normally distributed, random fluctuations that are uncorrelated between seasons, or in subsequent years. The magnitude of variability for both summer and winter is well correlated with mean wintertime balance, which reflects the climatic setting. Collectively, summertime variability exceeds wintertime variability, except for maritime glaciers. Trends in annual mass balance are generally negative, driven primarily by summertime changes. Approximately 25 % of annual-mean records show statistically significant negative trends when judged in isolation. In aggregate, the global trend is negative and significant. We further evaluate the magnitude of trends relative to the variability. We find that, on average, trends are approximately -0.2 standard deviations per decade, although there is a broad spread among individual glaciers. Finally, for two long records we also compare mass-balance trends and variability with nearby meteorological stations. We find significant differences among stations meaning caution is warranted in interpreting any point measurement (such as mass balance) as representative of region-wide behavior. By placing observed trends in the context of natural variability, the results are useful for interpreting past glacial history, and for placing constraints on future predictability.

  3. A mass balance method for non-intrusive measurements of surface-air trace gas exchange

    NASA Astrophysics Data System (ADS)

    Denmead, O. T.; Harper, L. A.; Freney, J. R.; Griffith, D. W. T.; Leuning, R.; Sharpe, R. R.

    A mass balance method is described for calculating gas production from a surface or volume source in a small test plot from measurements of differences in the horizontal fluxes of the gas across upwind and downwind boundaries. It employs a square plot, 24 m×24 m, with measurements of gas concentration at four heights (up to 3.5 m) along each of the four boundaries. Gas concentrations are multiplied by the appropriate vector winds to yield the horizontal fluxes at each height on each boundary. The difference between these fluxes integrated over downwind and upwind boundaries represents production. Illustrations of the method, which involve exchanges of methane and carbon dioxide, are drawn from experiments with landfills, pastures and grazing animals. Tests included calculation of recovery rates from known gas releases and comparisons with a conventional micrometeorological approach and a backward dispersion model. The method performed satisfactorily in all cases. Its sensitivity for measuring exchanges of CO 2, CH 4 and N 2O in various scenarios was examined. As employed by us, the mass balance method can suffer from errors arising from the large number of gas analyses required for a flux determination, and becomes unreliable when there are light winds and variable wind directions. On the other hand, it is non-disturbing, has a simple theoretical basis, is independent of atmospheric stability or the shape of the wind profile, and is appropriate for flux measurement in situations where conventional micrometeorological methods can not be used, e.g. for small plots, elevated point sources, and heterogeneous surface sources.

  4. Overview of Ice-Sheet Mass Balance and Dynamics from ICESat Measurements

    NASA Technical Reports Server (NTRS)

    Zwally, H. Jay

    2010-01-01

    The primary purpose of the ICESat mission was to determine the present-day mass balance of the Greenland and Antarctic ice sheets, identify changes that may be occurring in the surface-mass flux and ice dynamics, and estimate their contributions to global sea-level rise. Although ICESat's three lasers were planned to make continuous measurements for 3 to 5 years, the mission was re-planned to operate in 33-day campaigns 2 to 3 times each year following failure of the first laser after 36 days. Seventeen campaigns were conducted with the last one in the Fall of 2009. Mass balance maps derived from measured ice-sheet elevation changes show that the mass loss from Greenland has increased significantly to about 170 Gt/yr for 2003 to 2007 from a state of near balance in the 1990's. Increased losses (189 Gt/yr) from melting and dynamic thinning are over seven times larger'than increased gains (25 gt/yr) from precipitation. Parts of the West Antarctic ice sheet and the Antarctic Peninsula are losing mass at an increasing rate, but other parts of West Antarctica and the East Antarctic ice sheet are gaining mass at an increasing rate. Increased losses of 35 Gt/yr in Pine Island, Thwaites-Smith, and Marie-Bryd.Coast are more than balanced by gains in base of Peninsula and ice stream C, D, & E systems. From the 1992-2002 to 2003-2007 period, the overall mass balance for Antarctica changed from a loss of about 60 Gt/yr to near balance or slightly positive.

  5. Mass-balance Approach to Interpreting Weathering Reactions in Watershed Systems

    NASA Astrophysics Data System (ADS)

    Bricker, O. P.; Jones, B. F.; Bowser, C. J.

    2003-12-01

    The mass-balance approach is conceptually simple and has found widespread applications in many fields over the years. For example, chemists use mass balance (Stumm and Morgan, 1996) to sum the various species containing an element in order to determine the total amount of that element in the system (free ion, complexes). Glaciologists use mass balance to determine the changes in mass of glaciers ( Mayo et al., 1972 and references therein). Groundwater hydrologists use this method to interpret changes in water balance in groundwater systems ( Rasmussen and Andreasen, 1959; Bredehoeft et al., 1982; Heath, 1983; Konikow and Mercer, 1988; Freeze and Cherry, 1979; Ingebritsen and Sanford, 1998). This method has also been used to determine changes in chemistry along a flow path ( Plummer et al., 1983; Bowser and Jones, 1990) and to quantify lake hydrologic budgets using stable isotopes ( Krabbenhoft et al., 1994). Blum and Erel (see Chapter 5.12) discuss the use of strontium isotopes, Chapelle (see Chapter 5.14) treats carbon isotopes in groundwater, and Kendall and Doctor (see Chapter 5.11) and Kendall and McDonnell (1998) discuss the use of stable isotopes in mass balance. Although the method is conceptually simple, the parameters that define a mass balance are not always easy to measure. Watershed investigators use mass balance to determine physical and chemical changes in watersheds ( Garrels and Mackenzie, 1967; Plummer et al., 1991; O'Brien et al., 1997; Drever, 1997). Here we focus on describing the mass-balance approach to interpret weathering reactions in watershed systems including shallow groundwater.Because mass balance is simply an accounting of the flux of material into a system minus the flux of material out of the system, the geochemical mass-balance approach is well suited to interpreting weathering reactions in watersheds (catchments) and in other environmental settings (Drever, 1997). It is, perhaps, the most accurate and reliable way of defining

  6. Evaporation and the mass and energy balances of the Dead Sea (Invited)

    NASA Astrophysics Data System (ADS)

    Lensky, N.; Gavrieli, I.; Gertman, I.; Nehorai, R.; Lensky, I. M.; Lyakhovsky, V.; Dvorkin, Y.

    2009-12-01

    The Dead Sea is a hypersaline terminal lake experiencing a water level drop of about 1 m/yr over the last decade. The existing estimations for the water balance of the lake are widely variable, reflecting the unknown subsurface water inflow, the rate of evaporation, and the rate of salt accumulation at the lake bottom. To estimate these we calculate the energy and mass balances for the Dead Sea utilizing measured meteorological and hydrographical data from 1996 to 2009. The data is measured from a buoy located in the Dead Sea 5, km from the nearest shore. The data includes solar radiation (incoming), long wave radiation (downward and upward looking), wind velocity, relative humidity, air temperature, air pressure and water temperature profile. Using energy balance we calculate the evaporation rate, taking into account the impact of lowered surface water activity. From mass balance considerations we calculate the salt precipitation rate, which was about 0.1 m/yr during this period. Using an overall mass balance we get the relation between water inflows, which are the least constrained quantity, and the evaporation rate. The average annual inflow is 265-325 mcm/yr, corresponding to an evaporation rate of 1.1-1.2 m/yr. Higher inflows, suggested in previous studies, call for increased evaporation rate and are therefore not in line with the energy balance. We also take into account the spatial variations and discuss how well the data measured in the buoy represent the Dead Sea surface conditions.

  7. Testing the Mass Balance of the Laurentide Ice Sheet During the Last Glacial Maximum

    NASA Astrophysics Data System (ADS)

    Ullman, D. J.; Carlson, A. E.; Legrande, A. N.; Anslow, F. S.; Licciardi, J. M.; Caffee, M. W.

    2010-12-01

    Recent findings have suggested that the global Last Glacial Maximum occurred 26.5-20 ka. During this time, ice sheets were at their maximum extent and eustatic sea level was nearly 130 m lower than present. Such stability of Northern Hemisphere ice sheets suggests a nearly neutral net mass balance. Here we test the mass balance of the Laurentide Ice Sheet at the Last Glacial Maximum using an energy-mass balance model and two different ice sheet configurations. The energy-mass balance model is forced by simulated climate from the NASA Goddard Institute for Space Studies Model E-R, consistent with Last Glacial Maximum conditions. This coupled atmosphere-ocean global climate model contains water isotope tracers throughout the hydrologic cycle, which are used to constrain model skill against water isotopic records. Two model experiments are performed with different Laurentide Ice Sheet configurations: one using the ICE-5G geophysical reconstruction and the other using an alternative reconstruction based on a flow-line model that simulates glacier dynamics over deformable and rigid beds. These two reconstructions have widely contrasting ice sheet geometries at the Last Glacial Maximum, with the ICE-5G reconstruction having a much larger Keewatin Dome over west-central Canada, while the largest mass center according to the flow-line model is in the Labrador Dome over eastern Canada. This disparity in ice sheet geometry may result in large differences in simulated climate and net ice sheet mass balance. Initial results suggest that 1) the ICE-5G ice sheet forces a Last Glacial Maximum climate in conflict with paleoceanographic reconstructions of ocean circulation, whereas the flow-line ice sheet is in better agreement with circulation reconstructions; and 2) the initial increase in boreal summer insolation could trigger a negative mass balance for the Laurentide Ice Sheet by 21 ka, driving ice retreat. We will also compare our mass balance results with existing

  8. Improving the XAJ Model on the Basis of Mass-Energy Balance

    NASA Astrophysics Data System (ADS)

    Fang, Yuanghao; Corbari, Chiara; Zhang, Xingnan; Mancini, Marco

    2014-11-01

    The Xin’anjiang(XAJ) model is a conceptual model developed by the group led by Prof. Ren-Jun Zhao, which takes the pan evaporation as one of its input and then computes the effective evapotranspiration (ET) of the catchment by mass balance. Such scheme can ensure a good performance of discharge simulation but has obvious defects, one of which is that the effective ET is spatially-constant over the computation unit, neglecting the spatial variation of variables that influence the effective ET and therefore the simulation of ET and SM by the XAJ model, comparing with discharge, is less reliable. In this study, The XAJ model was improved to employ both energy and mass balance to compute the ET following the energy-mass balance scheme of FEST-EWB. model.

  9. Relations between atmospheric circulation and mass balance of South Cascade Glacier, Washington, USA

    USGS Publications Warehouse

    McCabe, G.J., Jr.; Fountain, A.G.

    1995-01-01

    The yearly net mass balance of South Cascade Glacier, Washington, has decreased since the mid-1970s. Resuls show that the decrease is primarily caused by a significant decrease in the winter mass balance. Changes in atmospheric circulation indicate a decrease in the movement of storms and moisture from the Pacific Ocean into the western contiguous United States. In addition, the increase in winter mean 700-mb heights over western Canada and the northern western contiguous United States indicates an increase in subsidence, which results in a warming and drying of the air that further reduces precipitation and also increases the ratio of rain to snow during the cold season. These factors contribute to below-average winter mass balances. -from Authors

  10. Gravimetric mass balance products for the Antarctic and Greenland ice sheet

    NASA Astrophysics Data System (ADS)

    Horwath, Martin; Groh, Andreas; Horvath, Alexander; Forsberg, Rene; Meister, Rakia; Shepherd, Andrew; Hogg, Anna; Muir, Alan

    2016-04-01

    Within the framework of ESA's Climate Change Initiative (CCI) mass balance products for both the Antarctic Ice Sheet (AIS) and the Greenland Ice Sheet (GIS) have been developed by the AIS_cci and the GIS_cci project. These Gravimetric Mass Balance (GMB) products are derived from satellite gravimetry data acquired by GRACE (Gravity Recovery and Climate Experiment), which is the only sensor directly sensitive to changes in mass. Using monthly GRACE gravity field solutions covering the period from 2002 until present two different GMB products are derived: (a) time series of monthly mass changes for the entire ice sheet and for individual drainage basins, and (b) gridded mass changes covering the entire ice sheet. The gridded product depicts spatial patterns of mass changes at a formal resolution of about 50 km, although the effective resolution provided by GRACE is about 200-500km. The algorithms used for the product generation have been selected within an open round robin experiment and are optimized to account for the complex GRACE error structures, to advance the limited spatial resolution and to separate signals super-imposed to mass changes of the cryosphere. Here the first release of the ESA CCI GMB products is presented. Both the basin averaged and the gridded products are assessed regarding their signal content and error characteristics. Finally, up-to-date mass balance estimates are presented for both ice sheets. The GMB products are freely accessible through data portals hosted by the AIS_cci and the GIS_cci project.

  11. Re-analysis of Alaskan benchmark glacier mass-balance data using the index method

    USGS Publications Warehouse

    Van Beusekom, Ashely E.; O'Nell, Shad R.; March, Rod S.; Sass, Louis C.; Cox, Leif H.

    2010-01-01

    At Gulkana and Wolverine Glaciers, designated the Alaskan benchmark glaciers, we re-analyzed and re-computed the mass balance time series from 1966 to 2009 to accomplish our goal of making more robust time series. Each glacier's data record was analyzed with the same methods. For surface processes, we estimated missing information with an improved degree-day model. Degree-day models predict ablation from the sum of daily mean temperatures and an empirical degree-day factor. We modernized the traditional degree-day model and derived new degree-day factors in an effort to match the balance time series more closely. We estimated missing yearly-site data with a new balance gradient method. These efforts showed that an additional step needed to be taken at Wolverine Glacier to adjust for non-representative index sites. As with the previously calculated mass balances, the re-analyzed balances showed a continuing trend of mass loss. We noted that the time series, and thus our estimate of the cumulative mass loss over the period of record, was very sensitive to the data input, and suggest the need to add data-collection sites and modernize our weather stations.

  12. ENSO influence on surface energy and mass balance at Shallap Glacier, Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Maussion, F.; Gurgiser, W.; Großhauser, M.; Kaser, G.; Marzeion, B.

    2015-05-01

    The El Niño/Southern Oscillation (ENSO) is a major driver of climate variability in the tropical Andes, where recent Niño and Niña events left an observable footprint on glacier mass balance. The nature and strength of the relationship between ENSO and glacier mass balance, however, varies between regions and time periods, leaving several unanswered questions about its exact mechanisms. The starting point of this study is a four-year long time series of distributed surface energy and mass balance (SEB/SMB) calculated using a process-based model driven by observations at Shallap Glacier (Cordillera Blanca, Peru). These data are used to calibrate a regression-based downscaling model that links the local SEB/SMB fluxes to atmospheric reanalysis variables on a monthly basis, allowing an unprecedented quantification of the ENSO influence on the SEB/SMB at climatological time scales (1980-2013, ERA-Interim period). We find a stronger and steadier anti-correlation between pacific sea surface temperature (SST) and glacier mass balance than previously reported. This relationship is most pronounced during the wet season (December-May) and at low altitudes where Niño (Niña) events are accompanied with a snowfall deficit (excess) and a higher (lower) radiation energy input. We detect a weaker but significant ENSO anti-correlation with total precipitation (Niño dry signal) and positive correlation with the sensible heat flux, but find no ENSO influence on sublimation. Sensitivity analyses comparing several downscaling methods and reanalysis datasets resulted in stable mass balance correlations with pacific SST but also revealed large uncertainties in computing the mass balance trend of the last decades. The newly introduced open-source downscaling tool can be applied easily to other glaciers in the tropics, opening new research possibilities on even longer time scales.

  13. ENSO influence on surface energy and mass balance at Shallap Glacier, Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Maussion, F.; Gurgiser, W.; Großhauser, M.; Kaser, G.; Marzeion, B.

    2015-08-01

    The El Niño/Southern Oscillation (ENSO) is a major driver of climate variability in the tropical Andes, where recent Niño and Niña events left an observable footprint on glacier mass balance. The nature and strength of the relationship between ENSO and glacier mass balance, however, varies between regions and time periods, leaving several unanswered questions about its exact mechanisms. The starting point of this study is a 4-year long time series of distributed surface energy and mass balance (SEB/SMB) calculated using a process-based model driven by observations at Shallap Glacier (Cordillera Blanca, Peru). These data are used to calibrate a regression-based downscaling model that links the local SEB/SMB fluxes to atmospheric reanalysis variables on a monthly basis, allowing an unprecedented quantification of the ENSO influence on the SEB/SMB at climatological time scales (1980-2013, ERA-Interim period). We find a stronger and steadier anti-correlation between Pacific sea-surface temperature (SST) and glacier mass balance than previously reported. This relationship is most pronounced during the wet season (December-May) and at low altitudes where Niño (Niña) events are accompanied with a snowfall deficit (excess) and a higher (lower) radiation energy input. We detect a weaker but significant ENSO anti-correlation with total precipitation (Niño dry signal) and positive correlation with the sensible heat flux, but find no ENSO influence on sublimation. Sensitivity analyses comparing several downscaling methods and reanalysis data sets resulted in stable mass balance correlations with Pacific SST but also revealed large uncertainties in computing the mass balance trend of the last decades. The newly introduced open-source downscaling tool can be applied easily to other glaciers in the tropics, opening new research possibilities on even longer time scales.

  14. Optimization of regional constraints for estimating the Greenland mass balance with GRACE level-2 data

    NASA Astrophysics Data System (ADS)

    Xu, Z.; Schrama, E.; van der Wal, W.

    2015-07-01

    Data from the Gravity Recovery and Climate Experiment (GRACE) satellite mission can be used to estimate the mass change rate for separate drainage systems (DSs) of the Greenland Ice Sheet (GrIS). One approach to do so is by inversion of the level-2 spherical harmonic data to surface mass changes in predefined regions, or mascons. However, the inversion can be numerically unstable for some individual DSs. This occurs mainly for DSs with a small mass change signal that are located in the interior region of Greenland. In this study, we present a modified mascon inversion approach with an improved implementation of the constraint equations to obtain better estimates for individual DSs. We use separate constraints for mass change variability in the coastal zone, where run-off takes place, and for the ice sheet interior above 2000 m, where mass changes are smaller. A multi-objective optimization approach is used to find optimal prior variances for these two areas based on a simulation model. Correlations between adjacent DSs are suppressed when our optimized prior variances are used, while the mass balance estimates for the combination of the DSs that make up the GrIS above 2000 m are not affected significantly. The resulting mass balance estimates for some DSs in the interior are significantly improved compared to an inversion with a single constraint, as determined by a comparison with mass balance estimates from surface mass balance modelling and discharge measurements. The rate of mass change of the GrIS for the period of January 2003 to December 2012 is found to be -266.1 ± 17.2 Gt yr-1 in the coastal zone and areas below 2000 m, and +8.2 ± 8.6 Gt yr-1 in the interior region.

  15. Evaluation of three long term mass balance records in Jotunheimen, southern Norway

    NASA Astrophysics Data System (ADS)

    Andreassen, Liss M.

    2013-04-01

    The accuracy of glacier surface mass-balance measurements depends on both the accuracy of the point observations and inter- and extrapolation of point values to spatially distributed values. Long series of measurements will seldom be perfectly homogeneous because of changes in personnel and procedure, and as there will be changes in glacier area (and elevation) when averaging the data. The Jotunheimen massif is the highest area in mainland Norway. Direct surface mass balance has been measured at Storbreen since 1949 and Hellstugubreen and Gråsubreen since 1962. These three mountain glaciers are reference glaciers of the World Glacier Monitoring Service. Four more glaciers in Jotunheimen were measured for shorter periods in the 1960/1970s. Moreover, measurements started on a small ice patch in 2010. The reference glaciers have been mapped repeatedly since measurements began, latest by laser scanning in 2009. The geodetic method has been used to calculate the cumulative surface mass balance. In this study the direct and geodetic mass balance results are presented and evaluated. Measurements reveal a remarked mass balance gradient in this region with smaller mass turnover towards east. All three long term glaciers have had a cumulative mass deficit since measurements began; over 1962-2010 the mean surface mass balance was -0.34 m w.e./a. The mass deficit has accelerated over the past decade, and the mean mass balance over 2001-2010 was -0.84 m w.e./a. Storbreen has lost about 1/5 of its volume since measurements began in 1949. Results reveal that the geodetic and direct measurements compare well for the glaciers, also for the latest mapping period 1997-2009, although discrepancies occur in some periods. Calibration and correction of the direct records with the geodetic results may be appropriate for some periods. The glacier changes of the three reference glaciers are finally compared with results from other glaciers in southern Norway for evaluation of the local and

  16. Response of glacier mass balance to climate change in the Tianshan Mountains during the second half of the twentieth century

    NASA Astrophysics Data System (ADS)

    Liu, Qiao; Liu, Shiyin

    2016-01-01

    Systematic differences in glacier mass balance response to climate warming are apparent in the Tianshan Mountains, which are primarily caused by different climatic regimes and glacier hypsography. Combined mass balance data of nine monitored glaciers in the Tianshan Mountains shows that most glaciers accelerated their mass losing rate since 1970s (averaged from -24.6 mm w.e. a-1 in 1957-1970 to -444.6 mm w.e. a-1 in 1971-2009), but also exhibiting discrepancy and consistency during the second half of the twentieth century. To see their climatic-mass balance relationships, we employ a simple temperature index mass balance model on five well monitored glaciers in Tianshan. The model is calibrated by the observed annual, summer and winter mass balance data over the period of 1957-1980 and validated over 1981-2002. A comparison of modeled and measured annual mass balance yields an overall standard deviation of 0.465 m w.e. during the period of model runs. The calibrated mass balance model is also used to perform sensitivity experiments, which indicates the significant differences of individual glaciers in response to climate changes. This study, for the first time, tests a temperature index mass balance model on the selected observed glaciers in the Tianshan Mountains. Although there exists considerable uncertainties, we propose its potential possibility of improvement and applicability for regional glacier mass balance reconstructions and future predictions.

  17. An Early Formed D'' Reservoir Reconciles Geochemical Mass Balance With Whole Mantle Convection Models

    NASA Astrophysics Data System (ADS)

    Tolstikhin, I. N.; Kramers, I.

    2004-12-01

    One of the most intriguing present-day problems in Earth sciences is reconciling whole mantle convection models (that follow from seismic tomography and dynamic modeling) and the chemical and isotopic mass balance of continents and depleted mantle, which favor partial-mantle convection. Specifically, geochemical observations point to an apparently isolated, early-formed reservoir deep in the Earth. The most important of these observations are: (1) The occurrence of solar noble gases in the mantle, which is in contrast with the extreme degassing of this reservoir indicated by mantle xenology; (2) specific isotopic compositions of mantle He, Ne and Xe point to a reservoir with low U/3He and 136Xe(Pu)/129Xe(I) ratios, implying both early formation and low degassing of this reservoir. We suggest that the core-mantle transition zone (termed D'') is the reservoir indicated by these observations. The material of D'' could comprise an early gabbroic-basaltic crust loaded with chondrite-like, late-accreting matter including a solar-wind irradiated regolith. If subducted, this material should accumulate above the metal core due to an intrinsic density contrast. Provided that it was not hydrated at the surface, so that subduction did not entail volatile loss, it could have retained its geochemical characteristics. We examined the consequences of this scenario by transport models envisaging: (1) Earth accretion accompanied by mantle melting and fractionation, core segregation, formation and recycling of mafic crust, degassing, and gas loss from the atmosphere, followed by (2) crust-mantle evolution involving continent growth and recycling. Comparison of calculated and observed parameters allows a solution of the model. The D'' is formed within a time interval from 40 to 80 Ma after formation of the solar system and comprises about 20% of the BSE inventory of incompatible (including heat-producing) elements. Because the bulk of the D'' material (basalt) is fractionated, its

  18. An Examination of Balanced Literacy Instructional Model Implemented to Youths with Hearing Loss

    ERIC Educational Resources Information Center

    Uzuner, Yildiz; Girgin, Umit; Kaya, Zehranur; Karasu, Guzin; Girgin, M. Cem; Erdiken, Behram; Cavkaytar, Serap; Tanridiler, Ayse

    2011-01-01

    Recently, the balanced literacy approach, a combination of whole language and skill development approaches has received attention in literacy instruction. The purpose of this school-based action research was to create a balanced literacy environment, and to describe the impacts of the various instructional activities based on the balanced literacy…

  19. Mass analysis for the Space Station ECLSS using the balance spreadsheet method

    NASA Technical Reports Server (NTRS)

    Chu, Wen-Ho

    1989-01-01

    The balance spreadsheet method is applied to mass analysis of the Environmental Control and Life Support System (ECLSS). The spreadsheet layout reduces the complexity of the ECLSS analysis by concisely defining the sources, sinks, and net changes in mass for each fluid. The analysis method is illustrated by using information from the latest Space Station ECLSS Architectural Control Documents and a given Space Station assembly sequence. The analysis results are plotted and discussed.

  20. Balancing

    NASA Astrophysics Data System (ADS)

    Harteveld, Casper

    At many occasions we are asked to achieve a “balance” in our lives: when it comes, for example, to work and food. Balancing is crucial in game design as well as many have pointed out. In games with a meaningful purpose, however, balancing is remarkably different. It involves the balancing of three different worlds, the worlds of Reality, Meaning, and Play. From the experience of designing Levee Patroller, I observed that different types of tensions can come into existence that require balancing. It is possible to conceive of within-worlds dilemmas, between-worlds dilemmas, and trilemmas. The first, the within-world dilemmas, only take place within one of the worlds. We can think, for example, of a user interface problem which just relates to the world of Play. The second, the between-worlds dilemmas, have to do with a tension in which two worlds are predominantly involved. Choosing between a cartoon or a realistic style concerns, for instance, a tension between Reality and Play. Finally, the trilemmas are those in which all three worlds play an important role. For each of the types of tensions, I will give in this level a concrete example from the development of Levee Patroller. Although these examples come from just one game, I think the examples can be exemplary for other game development projects as they may represent stereotypical tensions. Therefore, to achieve harmony in any of these forthcoming games, it is worthwhile to study the struggles we had to deal with.

  1. Great Lakes water quality scenario models: Operational feasibility -Lake Michigan Mass Balance models

    EPA Science Inventory

    An overview of the Lake Michigan Mass Balance models were provided (eutrophication/nutrients, atrazine, mercury, and PCBs) with emphasis on the PCB model post-audit and forecast for Lake Trout. Provided were modeling construct, model description, and primary results. An assessm...

  2. Dynamic spatially-explicit mass-balance modeling for targeted watershed phosphorus management II: Model Application

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cost-effective nonpoint source phosphorus (P) control should target the land areas at greatest risk for P loss. We combined mass-balance modeling and geographic analysis to identify and map high-risk areas for P export by integrating long-term P input/output accounting with spatially variable physi...

  3. MASS BALANCE MODELLING OF PCBS IN THE FOX RIVER/GREEN BAY COMPLEX

    EPA Science Inventory

    The USEPA Office of Research and Development developed and applies a multimedia, mass balance modeling approach to the Fox River/Green Bay complex to aid managers with remedial decision-making. The suite of models were applied to PCBs due to the long history of contamination and ...

  4. Single-Pan Balances, Buoyancy, and Gravity or "A Mass of Confusion."

    ERIC Educational Resources Information Center

    Battino, Rubin; Williamson, Arthur G.

    1984-01-01

    Discusses problems and pitfalls of working with single-pan balances and methods used to advertise their accuracy. Investigated manufacturers knowledge of buoyancy effects, relating provisions and recommendations made by various companies. Provides a routine for intercalibration of weight using dummy weights of approximately known mass. (JM)

  5. AN OVERVIEW OF THE LAKE MICHIGAN MASS BALANCE MODELING PROJECT: BACKGROUND, ACCOMPLISHMENTS, AND FUTURE WORK

    EPA Science Inventory

    Modeling associated with the Lake Michigan Mass Balance Project (LMMBP) is being conducted using WASP-type water quality models to gain a better understanding of the ecosystem transport and fate of polychlorinated biphenyls (PCBs), atrazine, mercury, and trans-nonachlor in Lake M...

  6. REVIEW OF VOLATILE ORGANIC COMPOUND SOURCE APPORTIONMENT BY CHEMICAL MASS BALANCE. (R826237)

    EPA Science Inventory

    The chemical mass balance (CMB) receptor model has apportioned volatile organic compounds (VOCs) in more than 20 urban areas, mostly in the United States. These applications differ in terms of the total fraction apportioned, the calculation method, the chemical compounds used ...

  7. Nitrate Removal in Two Relict Oxbow Urban Wetlands: A 15N Mass-balance Approach

    EPA Science Inventory

    A 15N-tracer method was used to quantify nitrogen (N) removal processes in two relict oxbow wetlands located adjacent to the Minebank Run restored stream reach in Baltimore County (Maryland, USA) during summer 2009 and early spring 2010. A mass-balance approach was used to determ...

  8. ATMOSPHERIC MERCURY DEPOSITION TO LAKE MICHIGAN DURING THE LAKE MICHIGAN MASS BALANCE STUDY

    EPA Science Inventory

    Wet and dry mercury (Hg) deposition were calculated to Lake Michigan using a hybrid receptor modeling framework. The model utilized mercury monitoring data collected during the Lake Michigan Mass Balance Study and the Atmospheric Exchange Over Lakes and Oceans Study together w...

  9. Relations between atmospheric circulation and mass balance of South Cascade Glacier, Washington, U.S.A.

    SciTech Connect

    McCabe, G.J.; Fountain, A.G.

    1995-08-01

    The yearly net mass balance of South Cascade Glacier, Washington, has decreased since the mid-1970s. Results show that the decrease in winter mass balance is caused, in part, by changes in winter mean atmospheric circulation that began during the mid-1970s. Approximately 60% of the variability in winter mass balance can be explained by variations in winter mean 700-mb heights over western Canada. Since the mid-1970s, there has been an increase in winter mean 700-mb heights over western Canada and the northern western contiguous United States and a decrease in winter mean 700-mb heights in the eastern North Pacific Ocean centered near the Aleutian Islands. These changes in atmospheric circulation indicate a decrease in the movement of storms and moisture from the Pacific Ocean into the western contiguous United States. In addition, the increase in winter mean 700-mb heights over western Canada and the northern western contiguous United States indicates an increase in subsidence, which results in a warming and drying of the air that further reduces precipitation and also increases the ratio of rain to snow during the cold season. These factors contribute to below-average winter mass balances. 43 refs., 13 figs.

  10. MICHTOX: A MASS BALANCE AND BIOACCUMULATION MODEL FOR TOXIC CHEMICALS IN LAKE MICHIGAN

    EPA Science Inventory

    MICHTOX is a toxic chemical mass balance and bioaccumulation model for Lake Michigan. It was developed for USEPA's Region V in support of the Lake Michigan Lake-wide Management Plan (LaMP) to provide guidance on expected water quality improvements in response to critical pollutan...

  11. LM-3: A High-resolution Lake Michigan Mass Balance Water Quality Model

    EPA Science Inventory

    This report is a user’s manual that describes the high-resolution mass balance model known as LM3. LM3 has been applied to Lake Michigan to describe the transport and fate of atrazine, PCB congeners, and chloride in that system. The model has also been used to model eutrophicat...

  12. Relations between winter 700-mb height anomalies and mass balance of South Cascade Glacier, Washington

    SciTech Connect

    McCabe, G.J.; Fountain, A.G.

    1995-12-31

    The yearly net mass balance of South Cascade Glacier, Washington, decreased during the mid-1970`s. Results show that the decrease is primarily caused by a significant decrease in the winter mass balance. The decrease in winter mass balance is caused, in part, by changes in winter mean atmospheric circulation that began during the mid-1970`s. Since the mid-1970`s, there has been an increase in winter mean atmospheric pressure over western Canada and the northern western contiguous US and a decrease in winter mean atmospheric pressure in the eastern North Pacific Ocean centered near the Aleutian islands. These changes in atmospheric circulation indicate a decrease in the movement of storms and moisture from the Pacific Ocean into the western contiguous US. In addition, the increase in atmospheric pressure over western Canada and the northern western contiguous US indicates an increase in subsidence, which results in a warming and drying of the air that further reduces precipitation and also increases the ratio of rain to snow during the cold season. These factors contribute to below-average winter mass balances.

  13. Thorium Mass Balance for the Moon from Lunar Prospector and Sample Data: Implications for Thermal Evolution

    NASA Technical Reports Server (NTRS)

    Jolliff, Bradley L.; Gillis, Jeffrey J.; Haskin, Larry A.

    2000-01-01

    A global lunar mass-balance model for Th based on Lunar Prospector gamma-ray and lunar sample data is presented within the context of major crustal terranes. The consequences of strong enrichment of Th in the Procellarum KREEP Terrane are discussed.

  14. THE LAKE MICHIGAN MASS BALANCE PROJECT: QUALITY ASSURANCE PLAN FOR MATHEMATICAL MODELLING

    EPA Science Inventory

    This report documents the quality assurance process for the development and application of the Lake Michigan Mass Balance Models. The scope includes the overall modeling framework as well as the specific submodels that are linked to form a comprehensive synthesis of physical, che...

  15. A heuristic simulation model of Lake Ontario circulation and mass balance transport

    USGS Publications Warehouse

    McKenna, J.E., Jr.; Chalupnicki, M.A.

    2011-01-01

    The redistribution of suspended organisms and materials by large-scale currents is part of natural ecological processes in large aquatic systems but can contribute to ecosystem disruption when exotic elements are introduced into the system. Toxic compounds and planktonic organisms spend various lengths of time in suspension before settling to the bottom or otherwise being removed. We constructed a simple physical simulation model, including the influence of major tributaries, to qualitatively examine circulation patterns in Lake Ontario. We used a simple mass balance approach to estimate the relative water input to and export from each of 10 depth regime-specific compartments (nearshore vs. offshore) comprising Lake Ontario. Despite its simplicity, our model produced circulation patterns similar to those reported by more complex studies in the literature. A three-gyre pattern, with the classic large counterclockwise central lake circulation, and a simpler two-gyre system were both observed. These qualitative simulations indicate little offshore transport along the south shore, except near the mouths of the Niagara River and Oswego River. Complex flow structure was evident, particularly near the Niagara River mouth and in offshore waters of the eastern basin. Average Lake Ontario residence time is 8 years, but the fastest model pathway indicated potential transport of plankton through the lake in as little as 60 days. This simulation illustrates potential invasion pathways and provides rough estimates of planktonic larval dispersal or chemical transport among nearshore and offshore areas of Lake Ontario. ?? 2011 Taylor & Francis.

  16. Influence of Persistent Wind Scour on the Surface Mass Balance of Antarctica

    NASA Technical Reports Server (NTRS)

    Das, Indrani; Bell, Robin E.; Scambos, Ted A.; Wolovick, Michael; Creyts, Timothy T.; Studinger, Michael; Fearson, Nicholas; Nicolas, Julien P.; Lenaerts, Jan T. M.; vandenBroeke, Michiel R.

    2013-01-01

    Accurate quantification of surface snow accumulation over Antarctica is a key constraint for estimates of the Antarctic mass balance, as well as climatic interpretations of ice-core records. Over Antarctica, near-surface winds accelerate down relatively steep surface slopes, eroding and sublimating the snow. This wind scour results in numerous localized regions (< or = 200 sq km) with reduced surface accumulation. Estimates of Antarctic surface mass balance rely on sparse point measurements or coarse atmospheric models that do not capture these local processes, and overestimate the net mass input in wind-scour zones. Here we combine airborne radar observations of unconformable stratigraphic layers with lidar-derived surface roughness measurements to identify extensive wind-scour zones over Dome A, in the interior of East Antarctica. The scour zones are persistent because they are controlled by bedrock topography. On the basis of our Dome A observations, we develop an empirical model to predict wind-scour zones across the Antarctic continent and find that these zones are predominantly located in East Antarctica. We estimate that approx. 2.7-6.6% of the surface area of Antarctica has persistent negative net accumulation due to wind scour, which suggests that, across the continent, the snow mass input is overestimated by 11-36.5 Gt /yr in present surface-mass-balance calculations.

  17. The seasonal in-situ mass balance, temperature and precipitation of Yala Glacier, Langtang Valley, Nepal, from 2011 to 2015

    NASA Astrophysics Data System (ADS)

    Stumm, Dorothea; Fujita, Koji; Gurung, Tika; Joshi, Sharad; Litt, Maxime; Shea, Joseph; Sherpa, Mingma; Sinisalo, Anna; Wagnon, Patrick

    2016-04-01

    In-situ glacier mass balance measurements are still scarce in the Hindu Kush Himalayan (HKH) region and little is known about the seasonal balances. The glaciers in the Nepalese Himalaya have been considered summer accumulation glacier types because of the assumption that the majority of the accumulation occurs in the summer months during the monsoon. The glacier mass balance of Yala Glacier in the Langtang Valley of Nepal has been measured using the glaciological method since autumn 2011. Stakes were measured biannually in pre- and post-monsoon, usually in early May and in November, respectively. The measured mass balance gradient for the summer balance was larger than the winter balance, which is typical for glaciers with distinct ablation and accumulation seasons. On Yala Glacier, the summer balance was negative, and the winter balance was positive in all years with measurements. However, the annual net balance was negative for all four mass balance years from 2011 to 2015. The mass balances were further compared to temperature and precipitation data measured at nearby climate stations during the same time periods. In October 2013 and 2014, the Central Himalayas received large amounts of precipitation brought by the cyclones Phailin and Hudhud. These precipitation events contributed to the summer balance since the measurements were taken after the cyclones passed. In conclusion, on Yala Glacier accumulation processes dominated ablation processes during the winter, and ablation processes dominated during the summer, which could be explained by the low elevation range of Yala Glacier and precipitation from westerlies in the winter. Hence, this should be kept in mind when using the term 'summer accumulation glacier' for Yala Glacier. For future research in the HKH region, seasonal mass balances should be measured, and the processes impacting the mass balance and the role of winter precipitation should be investigated for other glaciers in the HKH region.

  18. Mass and energy balance constraints on the biological production of chemicals from coal

    SciTech Connect

    Andrews, G.

    1990-01-01

    Several organic chemicals, including methane and ethanol, may be produced by the bioprocessing of coal. This may be done either by direct microbial attack on the coal, or indirectly by the bioprocessing of solubilized coal. As in chemical liquefaction and gasification, the relative amounts of the various products that can be produced are severely constrained by mass and energy balance considerations. The main differences in biological processing are that water is a ubiquitous reactant, carbon dioxide a common product, and that some of the carbon and nitrogen in the coal may go to the synthesis of new biomass rather than products. The conventional biotechnological yield analysis applied to coal processing has several interesting consequences. The mass balance reduces to a balance of available electrons, and coal has a similar oxidation/reduction state to both carbohydrates and biomass. This makes high product yields feasible particularly under anaerobic conditions, although leaving open the question of whether the relevant hydrolase enzymes exist. Recommendations are made on products, and combinations of two products, that may be made with high yields and economic return. The energy balance provides little extra information. A general intracellular energy balance can be written in terms of the production and consumption of ATP, but much of the necessary information on the metabolic pathways is currently not available for coal processing microorganisms. 9 refs., 2 figs., 2 tabs.

  19. Development of the ECLSS Sizing Analysis Tool and ARS Mass Balance Model Using Microsoft Excel

    NASA Technical Reports Server (NTRS)

    McGlothlin, E. P.; Yeh, H. Y.; Lin, C. H.

    1999-01-01

    The development of a Microsoft Excel-compatible Environmental Control and Life Support System (ECLSS) sizing analysis "tool" for conceptual design of Mars human exploration missions makes it possible for a user to choose a certain technology in the corresponding subsystem. This tool estimates the mass, volume, and power requirements of every technology in a subsystem and the system as a whole. Furthermore, to verify that a design sized by the ECLSS Sizing Tool meets the mission requirements and integrates properly, mass balance models that solve for component throughputs of such ECLSS systems as the Water Recovery System (WRS) and Air Revitalization System (ARS) must be developed. The ARS Mass Balance Model will be discussed in this paper.

  20. Snowline observations to remotely derive glacier-wide mass balance on four Kyrgyz glaciers from 2003 to 2015

    NASA Astrophysics Data System (ADS)

    Barandun, Martina; Huss, Matthias; Sold, Leo; Kienholz, Christian; Usubaliev, Ryskul; Bolch, Tobias; Hoelzle, Martin

    2016-04-01

    The monitoring of glacier mass balance in remote regions is challenging but vital for understanding the response of glaciers to climate change. Direct mass balance observations are sparse and discontinuous in the Kyrgyz Tien Shan and Pamir. The under-sampling problem of glacier change assessments limits change predictions and impact projections. In this study, we elaborate on novel approaches to derive sub-seasonal glacier mass balance based on remote snowline monitoring on four Kyrgyz glaciers for a period from 2003 to 2015. The proposed methodology is based on the information content of short-term changes in snowline elevation detected with repeated remote sensing imagery for both the quantities of winter accumulation and summer ablation. By backward modelling the observed snowline position and the glacier geometry are related to the glacier-wide mass balance. Snowline position over the glacier area is detected with a semi-automatic procedure on remote sensing images (Landsat, ASTER) and automatically on terrestrial photographs. We apply the methodology to four glaciers on which direct mass balance measurements have been (re)-initiated recently and use reanalysed and partly reconstructed mass balance series as a first source to validate our approach to remotely determine the seasonal glacier mass budget. In a second step, the derived glacier-wide mass balance is compared to geodetic mass balance calculations for the first decade of the 21st century.

  1. A Preliminary Model for Spacecraft Propulsion Performance Analysis Based on Nuclear Gain and Subsystem Mass-Power Balances

    NASA Technical Reports Server (NTRS)

    Chakrabarti, Suman; Schmidt, George R.; Thio, Y. C.; Hurst, Chantelle M.

    1999-01-01

    A preliminary model for spacecraft propulsion performance analysis based on nuclear gain and subsystem mass-power balances are presented in viewgraph form. For very fast missions with straight-line trajectories, it has been shown that mission trip time is proportional to the cube root of alpha. Analysis of spacecraft power systems via a power balance and examination of gain vs. mass-power ratio has shown: 1) A minimum gain is needed to have enough power for thruster and driver operation; and 2) Increases in gain result in decreases in overall mass-power ratio, which in turn leads to greater achievable accelerations. However, subsystem mass-power ratios and efficiencies are crucial: less efficient values for these can partially offset the effect of nuclear gain. Therefore, it is of interest to monitor the progress of gain-limited subsystem technologies and it is also possible that power-limited systems with sufficiently low alpha may be competitive for such ambitious missions. Topics include Space flight requirements; Spacecraft energy gain; Control theory for performance; Mission assumptions; Round trips: Time and distance; Trip times; Vehicle acceleration; and Minimizing trip times.

  2. Gulkana Glacier, Alaska-Mass balance, meteorology, and water measurements, 1997-2001

    USGS Publications Warehouse

    March, Rod S.; O'Neel, Shad

    2011-01-01

    The measured winter snow, maximum winter snow, net, and annual balances for 1997-2001 in the Gulkana Glacier basin are determined at specific points and over the entire glacier area using the meteorological, hydrological, and glaciological data. We provide descriptions of glacier geometry to aid in estimation of conventional and reference surface mass balances and descriptions of ice motion to aid in the understanding of the glacier's response to its changing geometry. These data provide annual estimates for area altitude distribution, equilibrium line altitude, and accumulation area ratio during the study interval. New determinations of historical area altitude distributions are given for 1900 and annually from 1966 to 2001. As original weather instrumentation is nearing the end of its deployment lifespan, we provide new estimates of overlap comparisons and precipitation catch efficiency. During 1997-2001, Gulkana Glacier showed a continued and accelerated negative mass balance trend, especially below the equilibrium line altitude where thinning was pronounced. Ice motion also slowed, which combined with the negative mass balance, resulted in glacier retreat under a warming climate. Average annual runoff augmentation by glacier shrinkage for 1997-2001 was 25 percent compared to the previous average of 13 percent, in accordance with the measured glacier volume reductions.

  3. Analysis of difference between direct and geodetic mass balance measurements at South Cascade Glacier, Washington

    USGS Publications Warehouse

    Krimmel, R.M.

    1999-01-01

    Net mass balance has been measured since 1958 at South Cascade Glacier using the 'direct method,' e.g. area averages of snow gain and firn and ice loss at stakes. Analysis of cartographic vertical photography has allowed measurement of mass balance using the 'geodetic method' in 1970, 1975, 1977, 1979-80, and 1985-97. Water equivalent change as measured by these nearly independent methods should give similar results. During 1970-97, the direct method shows a cumulative balance of about -15 m, and the geodetic method shows a cumulative balance of about -22 m. The deviation between the two methods is fairly consistent, suggesting no gross errors in either, but rather a cumulative systematic error. It is suspected that the cumulative error is in the direct method because the geodetic method is based on a non-changing reference, the bedrock control, whereas the direct method is measured with reference to only the previous year's summer surface. Possible sources of mass loss that are missing from the direct method are basal melt, internal melt, and ablation on crevasse walls. Possible systematic measurement errors include under-estimation of the density of lost material, sinking stakes, or poorly represented areas.

  4. California's Snow Gun and its implications for mass balance predictions under greenhouse warming

    NASA Astrophysics Data System (ADS)

    Howat, I.; Snyder, M.; Tulaczyk, S.; Sloan, L.

    2003-12-01

    Precipitation has received limited treatment in glacier and snowpack mass balance models, largely due to the poor resolution and confidence of precipitation predictions relative to temperature predictions derived from atmospheric models. Most snow and glacier mass balance models rely on statistical or lapse rate-based downscaling of general or regional circulation models (GCM's and RCM's), essentially decoupling sub-grid scale, orographically-driven evolution of atmospheric heat and moisture. Such models invariably predict large losses in the snow and ice volume under greenhouse warming. However, positive trends in the mass balance of glaciers in some warming maritime climates, as well as at high elevations of the Greenland Ice Sheet, suggest that increased precipitation may play an important role in snow- and glacier-climate interactions. Here, we present a half century of April snowpack data from the Sierra Nevada and Cascade mountains of California, USA. This high-density network of snow-course data indicates that a gain in winter snow accumulation at higher elevations has compensated loss in snow volume at lower elevations by over 50% and has led to glacier expansion on Mt. Shasta. These trends are concurrent with a region-wide increase in winter temperatures up to 2° C. They result from the orographic lifting and saturation of warmer, more humid air leading to increased precipitation at higher elevations. Previous studies have invoked such a "Snow Gun" effect to explain contemporaneous records of Tertiary ocean warming and rapid glacial expansion. A climatological context of the California's "snow gun" effect is elucidated by correlation between the elevation distribution of April SWE observations and the phase of the Pacific Decadal Oscillation and the El Nino Southern Oscillation, both controlling the heat and moisture delivered to the U.S. Pacific coast. The existence of a significant "Snow Gun" effect presents two challenges to snow and glacier mass

  5. An Examination of Orthoptic Vision and Balance Performance of Nonhandicapped and Learning Disabled Children.

    ERIC Educational Resources Information Center

    Folsom-Meek, Sherry L.; And Others

    This study compared orthoptic vision development and balance performance of nonhandicapped and learning disabled children between the ages of 10 and 13 years of age. Each subject was individually administered two orthoptic vision screening tests (Cover Test and Biopter), a dynamic balance test using a changing consistency board, and two static…

  6. Examining Teachers' Beliefs about and Implementation of a Balanced Literacy Framework

    ERIC Educational Resources Information Center

    Bingham, Gary E.; Hall-Kenyon, Kendra M.

    2013-01-01

    While many embrace balanced literacy as a framework for quality literacy instruction, the way in which teachers operationalise the tenets of balanced literacy can vary greatly. In the present study, 581 teachers in the United States completed questionnaires concerning: (a) their beliefs about literacy skills and literacy instructional strategies…

  7. The impact of Saharan dust events on long-term glacier mass balance in the Alps

    NASA Astrophysics Data System (ADS)

    Bauder, A.; Gabbi, J.; Huss, M.; Schwikowski, M.

    2014-12-01

    Saharan dust falls are frequently observed in the Alpine region and are easily recognized by the unique yellowish coloration of the snow surface. Such Saharan dust events contribute to a large part to the total mineral dust deposited in snow and impact the surface energy budget by reducing the snow and ice albedo. In this study we investigate the long-term effect of such Saharan dust events on the surface albedo and the glacier's mass balance. The analysis is performed over the period 1914-2013 for two field sites on Claridenfirn, Swiss Alps, where an outstanding 100-year record of seasonal mass balance measurements is available. Based on the detailed knowledge about the mass balance, annual melt and accumulation rates are derived. A firn/ice core drilled at the glacier saddle of Colle Gnifetti (Swiss Alps) provides information on the impurity concentration in precipitation over the last century. A mass balance model combined with a parameterization for snow and ice albedo based on the specific surface area of snow and the snow impurity concentration is employed to assess the dust-albedo feedback. In order to track the position and thickness of snow layers a snow density model is implemented. Atmospheric dust enters the system of snow layers by precipitation and remains in the corresponding layer as long as there is no melt. When melt occurs, the water-insoluble part of the dust of the melted snow is supposed to accumulate in the top surface layer. The upper site has experienced only positive net mass balance and dust layers are continuously buried so that the impact of strong Saharan dust events is mainly restricted to the corresponding year. In the case of the lower site, the surface albedo is more strongly influenced by dust events of previous years due to periods with negative mass balances. Model results suggest that the enhanced melting in the 1940s yield even higher dust concentrations in 1947 compared to years with exceptional high Saharan dust deposition

  8. Estimation of Greenland's Ice Sheet Mass Balance Using ICESat and GRACE Data

    NASA Astrophysics Data System (ADS)

    Slobbe, D.; Ditmar, P.; Lindenbergh, R.

    2007-12-01

    Data of the GRACE gravity mission and the ICESat laser altimetry mission are used to create two independent estimates of Greenland's ice sheet mass balance over the full measurement period. For ICESat data, a processing strategy is developed using the elevation differences of geometrically overlapping footprints of both crossing and repeated tracks. The dataset is cleaned using quality flags defined by the GLAS science team. The cleaned dataset reveals some strong, spatially correlated signals that are shown to be related to physical phenomena. Different processing strategies are used to convert the observed temporal height differences to mass changes for 6 different drainage systems, further divided into a region above and below 2000 meter elevation. The results are compared with other altimetry based mass balance estimates. In general, the obtained results confirm trends discovered by others, but we also show that the choice of processing strategy strongly influences our results, especially for the areas below 2000 meter. Furthermore, GRACE based monthly variations of the Earth's gravity field as processed by CNES, CSR, GFZ and DEOS are used to estimate the mass balance change for North and South Greenland. It is shown that our results are comparable with recently published GRACE estimates (mascon solutions). On the other hand, the estimates based on GRACE data are only partly confirmed by the ICESat estimates. Possible explanations for the obvious differences will be discussed.

  9. Analysis of the mass balance time series of glaciers in the Italian Alps

    NASA Astrophysics Data System (ADS)

    Carturan, L.; Baroni, C.; Brunetti, M.; Carton, A.; Dalla Fontana, G.; Salvatore, M. C.; Zanoner, T.; Zuecco, G.

    2015-10-01

    This work presents an analysis of the mass balance series of nine Italian glaciers, which were selected based on the length, continuity and reliability of observations. All glaciers experienced mass loss in the observation period, which is variable for the different glaciers and ranges between 10 and 47 years. The longest series display increasing mass loss rates, that were mainly due to increased ablation during longer and warmer ablation seasons. The mean annual mass balance (Ba) in the decade from 2004 to 2013 ranged from -1788 mm to -763 mm w.e. yr-1. Low-altitude glaciers with low elevation ranges are more out of balance than the higher, larger and steeper glaciers, which maintain residual accumulation areas in their upper reaches. The response of glaciers is mainly controlled by the combination of October-May precipitation and June-September temperature, but rapid geometric adjustments and atmospheric changes lead to modifications in their response to climatic variations. In particular, a decreasing correlation of Ba with the June-September temperature and an increasing correlation with October-May precipitation are observed for some glaciers. In addition, the October-May temperature tends to become significantly correlated with Ba, possibly indicating a decrease in the fraction of solid precipitation, and/or increased ablation, during the accumulation season. Because most of the monitored glaciers have no more accumulation area, their observations series are at risk due to their impending extinction, thus requiring a soon replacement.

  10. Analysis of the mass balance time series of glaciers in the Italian Alps

    NASA Astrophysics Data System (ADS)

    Carturan, Luca; Baroni, Carlo; Brunetti, Michele; Carton, Alberto; Dalla Fontana, Giancarlo; Salvatore, Maria Cristina; Zanoner, Thomas; Zuecco, Giulia

    2016-03-01

    This work presents an analysis of the mass balance series of nine Italian glaciers, which were selected based on the length, continuity and reliability of observations. All glaciers experienced mass loss in the observation period, which is variable for the different glaciers and ranges between 10 and 47 years. The longest series display increasing mass loss rates, which were mainly due to increased ablation during longer and warmer ablation seasons. The mean annual mass balance (Ba) in the decade from 2004 to 2013 ranged from -1788 to -763 mm w.e. yr-1. Low-altitude glaciers with low range of elevation are more out of balance than the higher, larger and steeper glaciers, which maintain residual accumulation areas in their upper reaches. The response of glaciers is mainly controlled by the combination of October-May precipitations and June-September temperatures, but rapid geometric adjustments and atmospheric changes lead to modifications in their response to climatic variations. In particular, a decreasing correlation of Ba with the June-September temperatures and an increasing correlation with October-May precipitations are observed for some glaciers. In addition, the October-May temperatures tend to become significantly correlated with Ba, possibly indicating a decrease in the fraction of solid precipitation, and/or increased ablation, during the accumulation season. Because most of the monitored glaciers have no more accumulation area, their observations series are at risk due to their impending extinction, thus requiring a replacement soon.

  11. 3D viscosity maps for Greenland and effect on GRACE mass balance estimates

    NASA Astrophysics Data System (ADS)

    van der Wal, Wouter; Xu, Zheng

    2016-04-01

    The GRACE satellite mission measures mass loss of the Greenland ice sheet. To correct for glacial isostatic adjustment numerical models are used. Although generally found to be a small signal, the full range of possible GIA models has not been explored yet. In particular, low viscosities due to a wet mantle and high temperatures due to the nearby Iceland hotspot could have a significant effect on GIA gravity rates. The goal of this study is to present a range of possible viscosity maps, and investigate the effect on GRACE mass balance estimates. Viscosity is derived using flow laws for olivine. Mantle temperature is computed from global seismology models, based on temperature derivatives for different mantle compositions. An indication for grain sizes is obtained by xenolith findings at a few locations. We also investigate the weakening effect of the presence of melt. To calculate gravity rates, we use a finite-element GIA model with the 3D viscosity maps and the ICE-5G loading history. GRACE mass balances for mascons in Greenland are derived with a least-squares inversion, using separate constraints for the inland and coastal areas in Greenland. Biases in the least-squares inversion are corrected using scale factors estimated from a simulation based on a surface mass balance model (Xu et al., submitted to The Cryosphere). Model results show enhanced gravity rates in the west and south of Greenland with 3D viscosity maps, compared to GIA models with 1D viscosity. The effect on regional mass balance is up to 5 Gt/year. Regional low viscosity can make present-day gravity rates sensitivity to ice thickness changes in the last decades. Therefore, an improved ice loading history for these time scales is needed.

  12. Modeling past and future mass balance and discharge of Gulkana Glacier, Alaska

    NASA Astrophysics Data System (ADS)

    Roth, A. C.; Hock, R. M.; Arendt, A. A.; Zhang, J.

    2010-12-01

    The trends of climate change indicate that glacier melt will continue to increase. It is imperative that we understand and quantify how this will affect freshwater river runoff and downstream hydrology in order to better inform local response, policy, and resource management. The purpose of this study was to calibrate a model of discharge and mass balance of Gulkana Glacier and predict the glacier’s response to climate change. Gulkana Glacier is a U.S. Geological Survey (USGS) benchmark glacier located on the south flank of the eastern Alaska Range with an area of 15 km2. Using a temperature-index model including potential clear-sky direct radiation, discharge and mass balance of Gulkana Glacier were simulated over the period of 1967-2009 with a daily time step and a 40 m resolution DEM. Input data for the model were daily temperatures and precipitation data obtained from the USGS climate station near the glacier. Model parameters including precipitation lapse rate, precipitation correction, snowfall correction, melt factor, radiation melt factor for ice, and radiation melt factor for snow, were calibrated until the best agreement between measured and simulated discharged and winter, summer, and annual mass balance data was obtained. Future climate data defined by three time slices (2010-2019, 2050-2059, and 2090-2099) were obtained by a hierarchical climate modeling system, in which the CCSM3 simulations were downscaled with the high resolution regional model Arctic MM5. The 21st century climate is based on the middle-of-the-road A1B scenario, which represents balanced fossil and non-fossil fuel use. The mean temperature difference between each time slice and the mean measured temperature for 2000-2009 was found. These values were added to the daily temperatures for 2000-2009 and the model was used to calculate future discharge and mass balance for each time slice. Precipitation input was the measured 2000-2009 data for each time slice. Compared to the 2000

  13. Association of Body Mass Index With Self-Report and Performance-Based Measures of Balance and Mobility

    PubMed Central

    Wert, David M.; Hile, Elizabeth S.; Studenski, Stephanie A.; Brach, Jennifer S.

    2011-01-01

    Background The incidence of obesity is increasing in older adults, with associated worsening in the burden of disability. Little is known about the impact of body mass index (BMI) on self-report and performance-based balance and mobility measures in older adults. Objective The purposes of this study were (1) to examine the association of BMI with measures of balance and mobility and (2) to explore potential explanatory factors. Design This was a cross-sectional, observational study. Methods Older adults (mean age=77.6 years) who participated in an ongoing observational study (N=120) were classified as normal weight (BMI=18.5–24.9 kg/m2), overweight (BMI=25.0–29.9 kg/m2), moderately obese (BMI=30.0–34.9 kg/m2), or severely obese (BMI≥35 kg/m2). Body mass index data were missing for one individual; thus, data for 119 participants were included in the analysis. Mobility and balance were assessed using self-report and performance-based measures and were compared among weight groups using analysis of variance and chi-square analysis for categorical data. Multiple linear regression analysis was used to examine the association among BMI, mobility, and balance after controlling for potential confounding variables. Results Compared with participants who were of normal weight or overweight, those with moderate or severe obesity were less likely to report their mobility as very good or excellent (52%, 55%, 39%, and 6%, respectively); however, there was no difference in self-report of balance among weight groups. Participants with severe obesity (n=17) had the lowest levels of mobility on the performance-based measures, followed by those who were moderately obese (n=31), overweight (n=42), and of normal weight (n=29). There were no differences on performance-based balance measures among weight groups. After controlling for age, sex, minority status, physical activity level, education level, and comorbid conditions, BMI still significantly contributed to mobility (

  14. Mass balance-based regression modeling of PAHs accumulation in urban soils, role of urban development.

    PubMed

    Peng, Chi; Wang, Meie; Chen, Weiping; Chang, Andrew C

    2015-02-01

    We investigated the polycyclic aromatic hydrocarbons (PAHs) contents in 68 soils samples collected at housing developments that represent different length of development periods across Beijing. Based on the data, we derived a mass balanced mathematical model to simulate the dynamics of PAH accumulations in urban soils as affected by the urban developments. The key parameters were estimated by fitting the modified mass balance model to the data of PAH concentrations vs. building age of the sampling green area. The total PAH concentrations would increase from the baseline of 267 ng g(-1) to 3631 ng g(-1) during the period of 1978-2048. It showed that the dynamic changes in the rates of accumulations of light and heavy PAH species were related to the shifting of sources of fuels, combustion efficiencies, and amounts of energy consumed during the course of development. PMID:25489746

  15. Reconstruction of mass balance variations for Franz Josef Glacier, New Zealand, 1913 to 1989

    SciTech Connect

    Woo, Mingko Woo ); Fitzharris, B.B. )

    1992-11-01

    A model of mass balance is constructed for the Franz Josef Glacier on the west coast of New Zealand. It uses daily data from a nearby, but short-record climate station. The model is extended back to 1913 by creating hybrid climate data from a long-record, but more distant, climate station. Its monthly data provide long-term temperature and precipitation trends, and daily fluctuations are simulated using a stochastic approach that is tuned to the characteristics of the short-record station. The glacier model provides estimates of equilibrium-line altitudes which are in reasonable agreement with those observed, and variations of cumulative mass balance that correspond with patterns of advance and retreat of the glacier terminus.

  16. Progress toward Consensus Estimates of Regional Glacier Mass Balances for IPCC AR5

    NASA Astrophysics Data System (ADS)

    Arendt, A. A.; Gardner, A. S.; Cogley, J. G.

    2011-12-01

    Glaciers are potentially large contributors to rising sea level. Since the last IPCC report in 2007 (AR4), there has been a widespread increase in the use of geodetic observations from satellite and airborne platforms to complement field observations of glacier mass balance, as well as significant improvements in the global glacier inventory. Here we summarize our ongoing efforts to integrate data from multiple sources to arrive at a consensus estimate for each region, and to quantify uncertainties in those estimates. We will use examples from Alaska to illustrate methods for combining Gravity Recovery and Climate Experiment (GRACE), elevation differencing and field observations into a single time series with related uncertainty estimates. We will pay particular attention to reconciling discrepancies between GRACE estimates from multiple processing centers. We will also investigate the extent to which improvements in the glacier inventory affect the accuracy of our regional mass balances.

  17. Base flow separation: A comparison of analytical and mass balance methods

    NASA Astrophysics Data System (ADS)

    Lott, Darline A.; Stewart, Mark T.

    2016-04-01

    Base flow is the ground water contribution to stream flow. Many activities, such as water resource management, calibrating hydrological and climate models, and studies of basin hydrology, require good estimates of base flow. The base flow component of stream flow is usually determined by separating a stream hydrograph into two components, base flow and runoff. Analytical methods, mathematical functions or algorithms used to calculate base flow directly from discharge, are the most widely used base flow separation methods and are often used without calibration to basin or gage-specific parameters other than basin area. In this study, six analytical methods are compared to a mass balance method, the conductivity mass-balance (CMB) method. The base flow index (BFI) values for 35 stream gages are obtained from each of the seven methods with each gage having at least two consecutive years of specific conductance data and 30 years of continuous discharge data. BFI is cumulative base flow divided by cumulative total discharge over the period of record of analysis. The BFI value is dimensionless, and always varies from 0 to 1. Areas of basins used in this study range from 27 km2 to 68,117 km2. BFI was first determined for the uncalibrated analytical methods. The parameters of each analytical method were then calibrated to produce BFI values as close to the CMB derived BFI values as possible. One of the methods, the power function (aQb + cQ) method, is inherently calibrated and was not recalibrated. The uncalibrated analytical methods have an average correlation coefficient of 0.43 when compared to CMB-derived values, and an average correlation coefficient of 0.93 when calibrated with the CMB method. Once calibrated, the analytical methods can closely reproduce the base flow values of a mass balance method. Therefore, it is recommended that analytical methods be calibrated against tracer or mass balance methods.

  18. Quantification of colloidal and aqueous element transfer in soils: The dual-phase mass balance model

    USGS Publications Warehouse

    Bern, Carleton R.; Thompson, Aaron; Chadwick, Oliver A.

    2015-01-01

    Mass balance models have become standard tools for characterizing element gains and losses and volumetric change during weathering and soil development. However, they rely on the assumption of complete immobility for an index element such as Ti or Zr. Here we describe a dual-phase mass balance model that eliminates the need for an assumption of immobility and in the process quantifies the contribution of aqueous versus colloidal element transfer. In the model, the high field strength elements Ti and Zr are assumed to be mobile only as suspended solids (colloids) and can therefore be used to distinguish elemental redistribution via colloids from redistribution via dissolved aqueous solutes. Calculations are based upon element concentrations in soil, parent material, and colloids dispersed from soil in the laboratory. We illustrate the utility of this model using a catena in South Africa. Traditional mass balance models systematically distort elemental gains and losses and changes in soil volume in this catena due to significant redistribution of Zr-bearing colloids. Applying the dual-phase model accounts for this colloidal redistribution and we find that the process accounts for a substantial portion of the major element (e.g., Al, Fe and Si) loss from eluvial soil. In addition, we find that in illuvial soils along this catena, gains of colloidal material significantly offset aqueous elemental loss. In other settings, processes such as accumulation of exogenous dust can mimic the geochemical effects of colloid redistribution and we suggest strategies for distinguishing between the two. The movement of clays and colloidal material is a major process in weathering and pedogenesis; the mass balance model presented here is a tool for quantifying effects of that process over time scales of soil development.

  19. Evaluating different methods for glacier mass balance interpolation on a tropical glacier

    NASA Astrophysics Data System (ADS)

    Mölg, Nico; Ceballos, Jorge Luis

    2016-04-01

    Glaciers in the inner tropics receive precipitation throughout the year while the annual temperature amplitude is small. Therefore, a seasonal distinction in accumulation and ablation season as for mid-latitude glaciers is hardly applicable. In order to better understand the sub-annual glacier development and its relation to meteorological conditions, a mass balance programme with monthly resolution was established on Conejeras Glacier in the Cordillera Central in Colombia in 2006. After almost ten years of measurements the time series has been reanalysed. The results show a mass balance of around -25 m w.e. during this period and a strong correlation to several warm and cold phases of ENSO. Reanalysis of the monthly mass balance data reveal an often low correlation between ablation/accumulation and elevation. Quality and density of the measurement network allow for the application of several different interpolation methods, recommended ones as well as "outlawed" GIS methods like Kriging. In this study we show the advantages and disadvantages of a number of possibilities and try to rank their usability according to different conditions and purposes. The application of multiple methods can also be of advantage for the estimation of uncertainty ranges.

  20. Mass Balance of Perfluorinated Alkyl Acids in a Pristine Boreal Catchment.

    PubMed

    Filipovic, Marko; Laudon, Hjalmar; McLachlan, Michael S; Berger, Urs

    2015-10-20

    Mass balances of ten individual perfluorinated alkyl acids (PFAAs) in two nested pristine catchments in Northern Sweden with different sizes and hydrological functions were assembled for 2011-2012. Concentrations of PFAAs in rain and snowmelt, as well as in streamwater at the outlet of the two watersheds were measured and used to calculate PFAA atmospheric inputs to and riverine outputs from the catchments. The results generally showed a great excess of PFAA inputs for both catchments over the whole study year. However, during the spring flood period, the inputs and outputs were within a factor of 2 for several PFAAs and the streamwater showed PFAA patterns resembling the patterns in rain (as opposed to snowmelt), suggesting that snowmelt water infiltrating the ground had displaced water from the previous summer. Comparison of PFAA mass balances between the two catchments further suggested that atmospheric inputs of short-chain (replacement) perfluoroalkyl carboxylic acids had increased in the years before sampling, while inputs of the legacy perfluorooctane sulfonic acid had decreased. Overall, the mass balances indicate that a considerable portion of the PFAAs deposited from the atmosphere are stored in soil and may be released to surface and marine water environments in the future. PMID:26390224

  1. A review of remote sensing methods for glacier mass balance determination

    NASA Astrophysics Data System (ADS)

    Bamber, Jonathan L.; Rivera, Andres

    2007-10-01

    Airborne and satellite remote sensing is the only practical approach for deriving a wide area, regional assessment of glacier mass balance. A number of remote sensing approaches are possible for inferring the mass balance from some sort of proxy estimate. Here, we review the key methods relevant, in particular to Andean glaciers, discussing their strengths and weaknesses, and data sets that could be more fully exploited. We also consider future satellite missions that will provide advances in our observational capabilities. The methods discussed include observation of elevation changes, estimation of ice flux, repeat measurement of changes in spatial extent, snowline elevation and accumulation-ablation area ratio estimation. The methods are illustrated utilising a comprehensive review of results obtained from a number of studies of South American glaciers, focusing specifically on the Patagonian Icefields. In particular, we present some new results from Glaciar Chico, Southern Patagonian Icefield, Chile, where a variety of different satellite and in-situ data have been combined to estimate mass balance using a geodetic or elevation change approach over about a 25 yr period.

  2. A Range Correction for Icesat and Its Potential Impact on Ice-sheet Mass Balance Studies

    NASA Technical Reports Server (NTRS)

    Borsa, A. A.; Moholdt, G.; Fricker, H. A.; Brunt, Kelly M.

    2014-01-01

    We report on a previously undocumented range error in NASA's Ice, Cloud and land Elevation Satellite (ICESat) that degrades elevation precision and introduces a small but significant elevation trend over the ICESat mission period. This range error (the Gaussian-Centroid or 'G-C'offset) varies on a shot-to-shot basis and exhibits increasing scatter when laser transmit energies fall below 20 mJ. Although the G-C offset is uncorrelated over periods less than1 day, it evolves over the life of each of ICESat's three lasers in a series of ramps and jumps that give rise to spurious elevation trends of -0.92 to -1.90 cm yr(exp -1), depending on the time period considered. Using ICESat data over the Ross and Filchner-Ronne ice shelves we show that (1) the G-C offset introduces significant biases in ice-shelf mass balance estimates, and (2) the mass balance bias can vary between regions because of different temporal samplings of ICESat.We can reproduce the effect of the G-C offset over these two ice shelves by fitting trends to sample-weighted mean G-C offsets for each campaign, suggesting that it may not be necessary to fully repeat earlier ICESat studies to determine the impact of the G-C offset on ice-sheet mass balance estimates.

  3. Relation between mass balance aperture and hydraulic properties from field experiments in fractured rock in Sweden

    NASA Astrophysics Data System (ADS)

    Hjerne, Calle; Nordqvist, Rune

    2014-09-01

    Results from tracer tests are often used to infer connectivity and transport properties in bedrock. However, the amount of site-specific data from tracer tests is often very limited, while data from hydraulic tests are more abundant. It is therefore of great interest for predictive transport modeling to use hydraulic data to infer transport properties. In this study, data from cross-hole tracer tests carried out in crystalline bedrock in Sweden were compiled and analysed. The tests were performed within investigations made by the Swedish Nuclear Fuel and Waste Management Company (SKB) between 1978 and 2009 at five different locations. An empirical relationship between mass balance aperture and transmissivity was found and quantified by using 74 observations. The empirical relationship deviates considerably from the cubic law aperture, as mass balance aperture is found to be at least one order of magnitude larger than cubic law aperture. Hence, usage of cubic law aperture, derived from hydraulic testing, for transport predictions is unsuitable, as the advective transport time will be considerably underestimated. Another result, from the data set studied, is that mass balance aperture appears to correlate better to apparent storativity than to transmissivity.

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

    NASA Astrophysics Data System (ADS)

    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.

  5. Assessing the links between Greenland Ice Sheet Surface Mass Balance and Arctic climate using Climate Models and Observations

    NASA Astrophysics Data System (ADS)

    Mottram, Ruth; Rodehacke, Christian; Boberg, Fredrik; Langen, Peter; Sloth Madsen, Marianne; Høyer Svendsen, Synne; Yang, Shuting; Hesselbjerg Christensen, Jens; Olesen, Martin

    2016-04-01

    Changes in different parts of the Arctic cryosphere may have knock-on effects on other parts of the system. The fully coupled climate model EC-Earth, which includes the ice sheet model PISM, is a useful tool to examine interactions between sea ice, ice sheet, ocean and atmosphere. Here we present results from EC-Earth experimental simulations that show including an interactive ice sheet model changes ocean circulation, sea ice extent and regional climate with, for example, a dampening of the expected increase in Arctic temperatures under the RCP scenarios when compared with uncoupled experiments. However, the relatively coarse resolution of the climate model likely influences the calculated surface mass balance forcing applied to the ice sheet model and it is important therefore to evaluate the model performance over the ice sheet. Here, we assess the quality of the climate forcing from the GCM to the ice sheet model by comparing the energy balance and surface mass balance (SMB) output from EC-Earth with that from a regional climate model (RCM) run at very high resolution (0.05 degrees) over Greenland. The RCM, HIRHAM5, has been evaluated over a wide range of climate parameters for Greenland which allows us to be confident it gives a representative climate forcing for the Greenland ice sheet. To evaluate the internal variability in the climate forcing, we compare simulations from HIRHAM5 forced with both the EC-Earth historical emissions and the ERA-Interim reanalysis on the boundaries. The EC-Earth-PISM RCP8.5 scenario is also compared with an EC-Earth run without an ice sheet to assess the impact of an interactive ice sheet on likely future changes. To account for the resolution difference between the models we downscale both EC-Earth and HIRHAM5 simulations with a simple offline energy balance model (EBM).

  6. Improved Net Protein Balance, Lean Mass, and Gene Expression Changes With Oxandrolone Treatment in the Severely Burned

    PubMed Central

    Wolf, Steven E.; Thomas, Steven J.; Dasu, Mohan R.; Ferrando, Arny A.; Chinkes, David L.; Wolfe, Robert R.; Herndon, David N.

    2003-01-01

    Objective To determine the effects of the anabolic agent oxandrolone on muscle protein and gene expression in severely burned children. Summary Background Data The authors previously showed that oxandrolone increased net muscle protein synthesis in emaciated burned patients receiving delayed treatment for severe burns. They hypothesized that similar effects would be seen in those treated early after burn. Methods Thirty-two severely burned children were enrolled in a prospective randomized trial. Subjects underwent studies to assess leg protein net balance 5 days after the first excision and grafting procedure. Immediately after these studies, treatment with placebo (n = 18) or 0.1 mg/kg oxandrolone (n = 14) twice a day was started. One week after this, another net balance study was performed in each subject. Body weights and total body potassium counting were used to determine body compositional changes. Muscle biopsies were taken 1 week after treatment in oxandrolone subjects to examine gene expression changes with gene array (12,600 genes). Results Protein net balance did not change in the placebo group, while oxandrolone-treated subjects had a significant improvement. Body weights and fat free mass significantly decreased in the placebo group, while no changes were found in the oxandrolone-treated subjects. Expression changes were seen in 14 genes in the oxandrolone group compared to placebo. Some of these included myosin light chain (+2.7-fold change), tubulin (+2.3), calmodulin (−2.3), and protein phosphatase I inhibitor (−2.8). Conclusions Oxandrolone improves protein net balance and lean mass in the severely burned. These changes are associated with increased gene expression for functional muscle proteins. PMID:12796576

  7. Mass Balance Model for Sustainable Phosphorus Recovery in a US Wastewater Treatment Plant.

    PubMed

    Venkatesan, Arjun K; Hamdan, Abdul-Hakeem M; Chavez, Vanessa M; Brown, Jasmine D; Halden, Rolf U

    2016-01-01

    In response to limited phosphorus (P) reserves worldwide, several countries have demonstrated the prospect of recovering significant amounts of P from wastewater treatment plants (WWTPs). This technique uses enhanced biological P removal (EBPR) to concentrate P in sludge followed by chemical precipitation of P as struvite, a usable phosphate mineral. The present study models the feasibility of this enhanced removal and recovery technique in a WWTP in Arizona with design parameters typical of infrastructure in the United States. A mass balance was performed for existing treatment processes and modifications proposed to estimate the quantity of P that could be recovered under current and future flow conditions. Modeling results show that about 71 to 96% of the P being lost potentially could be recovered as struvite. About 491 ± 64 t yr of struvite may be recovered after process modification, which corresponds to $150,000 ± $20,000 yr in P sales to fertilizer industries. The process was projected to be economically feasible, with a payback period of 45 ± 30 yr in the studied WWTP and a much shorter duration of 3 ± 1 yr for WWTPs already using an EBPR process. Furthermore, modeling results suggest that P recovery can improve the quality of biosolids by favorably reducing the P:N ratio. Implementation of this strategy at US WWTPs may increase national security by reducing dependence of limited P resources. Considering all aspects of the recovery process with respect to environmental, economic, and social implications, the examined technique is concluded to represent a cost-attractive and sustainable method for P management in US WWTPs. PMID:26828163

  8. Glacier albedo decrease in the European Alps: potential causes and links with mass balances

    NASA Astrophysics Data System (ADS)

    Di Mauro, Biagio; Julitta, Tommaso; Colombo, Roberto

    2016-04-01

    Both mountain glaciers and polar ice sheets are losing mass all over the Earth. They are highly sensitive to climate variation, and the widespread reduction of glaciers has been ascribed to the atmospheric temperature increase. Beside this driver, also ice albedo plays a fundamental role in defining mass balance of glaciers. In fact, dark ice absorbs more energy causing faster glacier melting, and this can drive to more negative balances. Previous studies showed that the albedo of Himalayan glaciers and the Greenland Ice Sheet is decreasing with important rates. In this contribution, we tested the hypothesis that also glaciers in the European Alps are getting darker. We analyzed 16-year time series of MODIS (MODerate resolution Imaging Spectrometer) snow albedo from Terra (MOD13A1, 2000-2015) and Aqua (MYD13A1, 2002-2015) satellites. These data feature a spatial resolution of 500m and a daily temporal resolution. We evaluated the existence of a negative linear and nonlinear trend of the summer albedo values both at pixel and at glacier level. We also calculated the correlation between MODIS summer albedo and glacier mass balances (from the World Glaciological Monitoring Service, WGMS database), for all the glaciers with available mass balance during the considered period. In order to estimate the percentage of the summer albedo that can be explained by atmospheric temperature, we correlated MODIS albedo and monthly air temperature extracted from the ERA-Interim reanalysis dataset. Results show that decreasing trends exist with a strong spatial variability in the whole Alpine chain. In large glaciers, such as the Aletch (Swiss Alps), the trend varies significantly also within the glacier, showing that the trend is higher in the area across the accumulation and ablation zone. Over the 17 glaciers with mass balance available in the WGMS data set, 11 gave significant relationship with the MODIS summer albedo. Moreover, the comparison between ERA-Interim temperature

  9. Mass balance of Icelandic ice caps from CryoSat swath mode altimetry

    NASA Astrophysics Data System (ADS)

    Foresta, L.; Gourmelen, N.; Pálsson, F.; Willis, I. C.; Nienow, P. W.; Shepherd, A.

    2015-12-01

    Satellite altimetry has been traditionally used in the past to infer elevation of land ice, quantify changes in ice topography and infer mass balance over large and remote areas such as the Greenland and Antarctic ice sheets. Radar Altimetry (RA) is particularly well suited to this task due to its all-weather year-round capability for observing the ice surface. However, monitoring of ice caps has proven more challenging. The large footprint of a conventional radar altimeter and relatively coarse ground track coverage are less suited to monitoring comparatively small regions with complex topography, so that mass balance estimates from RA rely on extrapolation methods to regionalize elevation change.Since 2010, the Synthetic Interferometric Radar Altimeter (SIRAL) on board the ESA radar altimetry CryoSat mission has collected ice elevation measurements over ice caps. Ground track interspacing (~4km at 60°) is one order of magnitude smaller than ERS/ENVISAT missions and half of ICESAT's, providing dense spatial coverage. Additionally the Synthetic Aperture Radar Interferometric (SARIn) mode of CryoSat provides a reduced footprint and the ability to locate accurately the position of the surface reflection. Conventional altimetry provides the elevation of the Point Of Closest Approach (POCA) within each waveform, every 250 m along the flight path. Time evolution of POCA elevation is then used to investigate ice elevation change.Here, we present an assessment of the geodetic mass balance of Icelandic ice caps using a novel processing approach, swath altimetry, applied to CryoSat SARIn mode data. In swath mode altimetry, elevation beyond the POCA is extracted from the waveform when coherent echoes are present providing between one and two orders of magnitude more elevations when compared to POCA. We generate maps of ice elevation change that are then used to compute geodetic mass balance for the period 2010 to 2015. We compare our results to estimates generated using

  10. Ocean Basalt Simulator version 1 (OBS1): Trace element mass balance in adiabatic melting of a pyroxenite-bearing peridotite

    NASA Astrophysics Data System (ADS)

    Kimura, Jun-Ichi; Kawabata, Hiroshi

    2015-01-01

    present a new numerical trace element mass balance model for adiabatic melting of a pyroxenite-bearing peridotite for estimating mantle potential temperature, depth of melting column, and pyroxenite fraction in the source mantle for a primary ocean basalt/picrite. The Ocean Basalt Simulator version 1 (OBS1) uses a thermodynamic model of adiabatic melting of a pyroxenite-bearing peridotite with experimentally/thermodynamically parameterized liquidus-solidus intervals and source mineralogy. OBS1 can be used to calculate a sequence of adiabatic melting with two melting models, including (1) melting of peridotite and pyroxenite sources with simple mixing of their fractional melts (melt-melt mixing model), and (2) pyroxenite melting, melt metasomatism in the host peridotite, and melting of the metasomatized peridotite (source-metasomatism model). OBS1 can be used to explore (1) the fractions of peridotite and pyroxenite, (2) mantle potential temperature, (3) pressure of termination of melting, (4) degree of melting, and (5) residual mode of the sources. In order to constrain these parameters, the model calculates a mass balance for 26 incompatible trace elements in the sources and in the generated basalt/picrite. OBS1 is coded in an Excel spreadsheet and runs with VBA macros. Using OBS1, we examine the source compositions and conditions of the mid-oceanic ridge basalts, Loihi-Koolau basalts in the Hawaiian hot spot, and Jurassic Shatsky Rise and Mikabu oceanic plateau basalts and picrites. The OBS1 model shows the physical conditions, chemical mass balance, and amount of pyroxenite in the source peridotite, which are keys to global mantle recycling.