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Sample records for advanced circulation model

  1. Demonstration of an advanced circulation fludized bed coal combustor phase 1: Cold model study. Final report

    SciTech Connect

    Govind, R.

    1993-03-20

    It was found that there was a strong dependence of the density profile on the secondary air injection location and that there was a pronounced solid separation from the conveying gas, due to the swirl motion. Furthermore, the swirl motion generated strong internal circulation patterns and higher slip velocities than in the case of nonswirl motion as in an ordinary circulating fluidized bed. Radial solids flux profiles were measured at different axial locations. The general radial profile in a swirling circulating fluidized bed indicated an increased downward flow of solids near the bed walls, and strong variations in radial profiles along the axial height. For swirl numbers less than 0.9, which is typical for swirling circulating fluidized beds, there is no significant increase in erosion due to swirl motion inside the bed. Pending further investigation of swirl motion with combustion, at least from our cold model studies, no disadvantages due to the introduction of swirl motion were discovered.

  2. An advanced computational bioheat transfer model for a human body with an embedded systemic circulation.

    PubMed

    Coccarelli, Alberto; Boileau, Etienne; Parthimos, Dimitris; Nithiarasu, Perumal

    2016-10-01

    In the present work, an elaborate one-dimensional thermofluid model for a human body is presented. By contrast to the existing pure conduction-/perfusion-based models, the proposed methodology couples the arterial fluid dynamics of a human body with a multi-segmental bioheat model of surrounding solid tissues. In the present configuration, arterial flow is included through a network of elastic vessels. More than a dozen solid segments are employed to represent the heat conduction in the surrounding tissues, and each segment is constituted by a multilayered circular cylinder. Such multi-layers allow flexible delineation of the geometry and incorporation of properties of different tissue types. The coupling of solid tissue and fluid models requires subdivision of the arterial circulation into large and small arteries. The heat exchange between tissues and arterial wall occurs by convection in large vessels and by perfusion in small arteries. The core region, including the heart, provides the inlet conditions for the fluid equations. In the proposed model, shivering, sweating, and perfusion changes constitute the basis of the thermoregulatory system. The equations governing flow and heat transfer in the circulatory system are solved using a locally conservative Galerkin approach, and the heat conduction in the surrounding tissues is solved using a standard implicit backward Euler method. To investigate the effectiveness of the proposed model, temperature field evolutions are monitored at different points of the arterial tree and in the surrounding tissue layers. To study the differences due to flow-induced convection effects on thermal balance, the results of the current model are compared against those of the widely used modelling methodologies. The results show that the convection significantly influences the temperature distribution of the solid tissues in the vicinity of the arteries. Thus, the inner convection has a more predominant role in the human body heat

  3. Ocean General Circulation Models

    SciTech Connect

    Yoon, Jin-Ho; Ma, Po-Lun

    2012-09-30

    1. Definition of Subject The purpose of this text is to provide an introduction to aspects of oceanic general circulation models (OGCMs), an important component of Climate System or Earth System Model (ESM). The role of the ocean in ESMs is described in Chapter XX (EDITOR: PLEASE FIND THE COUPLED CLIMATE or EARTH SYSTEM MODELING CHAPTERS). The emerging need for understanding the Earth’s climate system and especially projecting its future evolution has encouraged scientists to explore the dynamical, physical, and biogeochemical processes in the ocean. Understanding the role of these processes in the climate system is an interesting and challenging scientific subject. For example, a research question how much extra heat or CO2 generated by anthropogenic activities can be stored in the deep ocean is not only scientifically interesting but also important in projecting future climate of the earth. Thus, OGCMs have been developed and applied to investigate the various oceanic processes and their role in the climate system.

  4. Testing Mantle Circulation Models

    NASA Astrophysics Data System (ADS)

    Webb, P.; Davies, D.; Davies, J.

    2008-12-01

    Over the past decade, a new family of mantle convection models have been developed, which are conditioned by recent plate motion history (e.g. Bunge et al., 1997). They are commonly known as 'mantle circulation models' and allow for comparisons between present-day model predictions and ever improving seismic tomography images (e.g. Li et al. 2008). In this work, we present results from systematic investigations into the influence of various model parameters upon final model prediction/tomography correlations, to obtain a better understanding of their relative importance. These include a range of material properties, such as the radial viscosity structure, the Clapeyron slope of mineral phase transitions and compressibility; in addition to other aspects, such as the initial condition for the simulation. For our comparisons, we focus in particular on two large robust mid-mantle seismic anomalies, which others have related to the subduction of the Farallon and Tethys plates (e.g. Romanowicz, 1980). While these features are recovered with some fidelity in most simulations, the match can vary greatly. We find that there is a great deal of information in this mismatch, which includes information on the plate motion history.

  5. LLNL Ocean General Circulation Model

    SciTech Connect

    Wickett, M. E.; Caldeira, K.; Duffy, P.

    2005-12-29

    The LLNL OGCM is a numerical ocean modeling tool for use in studying ocean circulation over a wide range of space and time scales, with primary applications to climate change and carbon cycle science.

  6. Modelling Circulation Control by Blowing

    DTIC Science & Technology

    1984-08-01

    circulation control is initially presented for the Coanda flaw of a wail jot around a circular cylinder in a free stream. The decay in the jet momentum...Jue to viscojs and ontiainment effects , has boon represented in the model by decaying the strength of each vortex is it flows downstream frorn the...slot. The model’s application has then boon extended to predict the effect of circulation control on other sh&,,os of aerofoll. The paper includes the

  7. Roadmap for cardiovascular circulation model.

    PubMed

    Safaei, Soroush; Bradley, Christopher P; Suresh, Vinod; Mithraratne, Kumar; Muller, Alexandre; Ho, Harvey; Ladd, David; Hellevik, Leif R; Omholt, Stig W; Chase, J Geoffrey; Müller, Lucas O; Watanabe, Sansuke M; Blanco, Pablo J; de Bono, Bernard; Hunter, Peter J

    2016-12-01

    Computational models of many aspects of the mammalian cardiovascular circulation have been developed. Indeed, along with orthopaedics, this area of physiology is one that has attracted much interest from engineers, presumably because the equations governing blood flow in the vascular system are well understood and can be solved with well-established numerical techniques. Unfortunately, there have been only a few attempts to create a comprehensive public domain resource for cardiovascular researchers. In this paper we propose a roadmap for developing an open source cardiovascular circulation model. The model should be registered to the musculo-skeletal system. The computational infrastructure for the cardiovascular model should provide for near real-time computation of blood flow and pressure in all parts of the body. The model should deal with vascular beds in all tissues, and the computational infrastructure for the model should provide links into CellML models of cell function and tissue function. In this work we review the literature associated with 1D blood flow modelling in the cardiovascular system, discuss model encoding standards, software and a model repository. We then describe the coordinate systems used to define the vascular geometry, derive the equations and discuss the implementation of these coupled equations in the open source computational software OpenCMISS. Finally, some preliminary results are presented and plans outlined for the next steps in the development of the model, the computational software and the graphical user interface for accessing the model.

  8. A blood circulation model for reference man

    SciTech Connect

    Leggett, R.W.; Eckerman, K.F.; Williams, L.R.

    1996-12-31

    A dynamic blood circulation model that predicts the movement and gradual dispersion of a bolus of material in the circulation after its intravenous injection into an adult human. The main purpose of the model is improve the dosimetry of internally deposited radionuclides that decay in the circulation to a significant extent. The model partitions the blood volume into 24 separate organs or tissues, right heart chamber, left heart chamber, pulmonary circulation, arterial outflow to the aorta and large arteries, and venous return via the large veins. Model results were compared to data obtained from injection of carbon 11 labeled carbon monoxide or rubidium 86.

  9. A blood circulation model for reference man

    SciTech Connect

    Leggett, R.W.; Eckerman, K.F.; Williams, L.R.

    1999-01-01

    This paper describes a dynamic blood circulation model that predicts the movement and gradual dispersal of a bolus of material in the circulation after its intravascular injection into an adult human. The main purpose of the model is to improve the dosimetry of internally deposited radionuclides that decay in the circulation to a significant extent. The total blood volume is partitioned into the blood contents of 24 separate organs or tissues, right heart chambers, left heart chambers, pulmonary circulation, arterial outflow to the systemic tissues (aorta and large arteries), and venous return from the systemic tissues (large veins). As a compromise between physical reality and computational simplicity, the circulation of blood is viewed as a system of first-order transfers between blood pools, with the delay time depending on the mean transit time across the pool. The model allows consideration of incomplete, tissue-dependent extraction of material during passage through the circulation and return of material from tissues to plasma.

  10. DEVELOPMENT OF WATER CIRCULATION MODEL INCLUDING IRRIGATION

    NASA Astrophysics Data System (ADS)

    Kotsuki, Shunji; Tanaka, Kenji; Kojiri, Toshiharu; Hamaguchi, Toshio

    It is well known that since agricultural water withdrawal has much affect on water circulation system, accurate analysis of river discharge or water balance are difficult with less regard for it. In this study, water circulation model composed of land surface model and distributed runoff model is proposed at 10km 10km resolution. In this model, irrigation water, which is estimated with land surface model, is introduced to river discharge analysis. The model is applied to the Chao Phraya River in Thailand, and reproduced seasonal water balance. Additionally, the discharge on dry season simulated with the model is improved as a result of including irrigation. Since the model, which is basically developed from global data sets, simulated seasonal change of river discharge, it can be suggested that our model has university to other river basins.

  11. Simple Model of the Circulation.

    ERIC Educational Resources Information Center

    Greenway, Clive A.

    1980-01-01

    Describes a program in BASIC-11 that explores the relationships between various variables in the circulatory system and permits manipulation of several semiindependent variables to model the effects of hemorrhage, drug infusions, etc. A flow chart and accompanying sample printout are provided; the program is listed in the appendix. (CS)

  12. Applications of a Venus thermospheric circulation model

    NASA Technical Reports Server (NTRS)

    Bougher, S. W.; Dickinson, R. E.; Ridley, E. C.; Roble, R. G.

    1986-01-01

    A variety of Pioneer Venus observations suggest a global scale, day-to-night Venus thermospheric circulation. Model studies of the dynamics and energetics of the Venus thermosphere are presented in order to address new driving, mixing and cooling mechanisms for an improved model simulation. The adopted approach was to reexamine the circulation by first using a previous two dimensional code to quantify those physical processes which can be inferred from the Pioneer Venus observations. Specifically, the model was used to perform sensitivity studies to determine the degree to which eddy cooling, eddy or wave drag, eddy diffusion and 15 micrometer radiational cooling are necessary to bring the model temperature and composition fields into agreement with observations. Three EUV heating cases were isolated for study. Global temperature and composition fields in good agreement with Pioneer data were obtained. Large scale horizontal winds 220 m/s were found to be consistent with the observed cold nightside temperatures and dayside bulges of O, CO and CO2. Observed dayside temperatures were obtained by using a 7 to 19% EUV heating efficiency profile. The enhanced 15 micrometer cooling needed for thermal balance is obtained using the best rate coefficient available for atomic O collisional excitation of CO2(0,1,0). Eddy conduction was not found to be a viable cooling mechanism due to the weakened global circulation. The strong 15 micrometer damping and low EUV efficiency imply a very weak dependence of the general circulation to solar cycle variability. The NCAR terrestrial thermospheric general circulation model was adapted for Venus inputs using the above two dimensional model parameters, to give a three dimensional benchmark for future Venus modelling work.

  13. A Circulation Model for Busy Public Libraries.

    ERIC Educational Resources Information Center

    Bagust, A.

    1983-01-01

    Develops stochastic model of library borrowing using Negative Binomial distribution applied to circulation data obtained from Huddersfield Public Library. Evidence concerning process of popularity decay is presented and method is given by which relegation tests can be constructed to maintain optimum turnover. Eight references and statistical…

  14. A paleoceanographic circulation and chemistry model

    SciTech Connect

    Southam, J.R. )

    1990-01-09

    We have developed a 3-D circulation and tracer field model for paleoceanographic applications. The development of the model was motivated by the desire to explore Cretaceous Oceanic Anoxic Events and ocean chemistry during glacial and interglacial modes of circulation. The bulk of paleoceanographic data is the consequences of biological processes operating in ancient oceans. This type of data represents the response to environmental conditions and can be used to reconstruct water mass properties. To infer both wind driven and thermohaline components of circulation in ancient oceans requires a model which relates circulation and water mass properties. With this motivation in mind we have formulated a model which satisfies the following criteria: (1) geostrophically balanced interior, (2) multiple sites for deep water production, (3) deep water production described by entraining plumes, (4) high vertical resolution in both velocity and property fields, (5) meridional varibility in wind stress and evaporation-precipitation rate, (6) applicable to basin scale where exchange with adjacent oceans described by flux conditions, and (7) the chemistry is coupled through the flux of particulate carbon sinking through the interior.

  15. Recent Advances in the Molecular Characterization of Circulating Tumor Cells

    PubMed Central

    Lowes, Lori E.; Allan, Alison L.

    2014-01-01

    Although circulating tumor cells (CTCs) were first observed over a century ago, lack of sensitive methodology precluded detailed study of these cells until recently. However, technological advances have now facilitated the identification, enumeration, and characterization of CTCs using a variety of methods. The majority of evidence supporting the use of CTCs in clinical decision-making has been related to enumeration using the CellSearch® system and correlation with prognosis. Growing evidence also suggests that CTC monitoring can provide an early indication of patient treatment response based on comparison of CTC levels before and after therapy. However, perhaps the greatest potential that CTCs hold for oncology lies at the level of molecular characterization. Clinical treatment decisions may be more effective if they are based on molecular characteristics of metastatic cells rather than on those of the primary tumor alone. Molecular characterization of CTCs (which can be repeatedly isolated in a minimally invasive fashion) provides the opportunity for a “real-time liquid biopsy” that allows assessment of genetic drift, investigation of molecular disease evolution, and identification of actionable genomic characteristics. This review focuses on recent advances in this area, including approaches involving immunophenotyping, fluorescence in situ hybridization (FISH), multiplex RT-PCR, microarray, and genomic sequencing. PMID:24633084

  16. Modeling mesoscale circulation of the Black Sea

    NASA Astrophysics Data System (ADS)

    Korotenko, K. A.

    2015-11-01

    An eddy-resolving (1/30)° version of the DieCAST low-dissipative model, adapted to the Black Sea circulation, is presented. Under mean climatological forcing, the model realistically reproduces major dominant large-scale and mesoscale structures of seasonal sea circulation, including the Rim Current, coastal anticyclonic eddies, mushroom currents, etc. Due to its extremely low dissipation and high resolution, the model makes it possible to trace the development of the baroclinic instability along the Turkish and Caucasian coasts, reproduce mesoscale structures generated by this mechanism, and assess the scales of these structures. The model also realistically reproduces short-term effects of bora winds on the evolution of subsurface layer structures.

  17. Circulating a Good Service Model at Its Core: Circulation!

    ERIC Educational Resources Information Center

    Hernandez, Edmee Sofia; Germain, Carol Anne, Ed.

    2009-01-01

    Circulation is the library's tireless foot soldier: it serves as the front gate to the library's services and resources. This service point is where most patrons enter and leave; and experience their first and last impressions--impressions that linger. In an age when academic libraries are facing meager budgets and declining usage statistics, this…

  18. Application of Improved Radiation Modeling to General Circulation Models

    SciTech Connect

    Michael J Iacono

    2011-04-07

    This research has accomplished its primary objectives of developing accurate and efficient radiation codes, validating them with measurements and higher resolution models, and providing these advancements to the global modeling community to enhance the treatment of cloud and radiative processes in weather and climate prediction models. A critical component of this research has been the development of the longwave and shortwave broadband radiative transfer code for general circulation model (GCM) applications, RRTMG, which is based on the single-column reference code, RRTM, also developed at AER. RRTMG is a rigorously tested radiation model that retains a considerable level of accuracy relative to higher resolution models and measurements despite the performance enhancements that have made it possible to apply this radiation code successfully to global dynamical models. This model includes the radiative effects of all significant atmospheric gases, and it treats the absorption and scattering from liquid and ice clouds and aerosols. RRTMG also includes a statistical technique for representing small-scale cloud variability, such as cloud fraction and the vertical overlap of clouds, which has been shown to improve cloud radiative forcing in global models. This development approach has provided a direct link from observations to the enhanced radiative transfer provided by RRTMG for application to GCMs. Recent comparison of existing climate model radiation codes with high resolution models has documented the improved radiative forcing capability provided by RRTMG, especially at the surface, relative to other GCM radiation models. Due to its high accuracy, its connection to observations, and its computational efficiency, RRTMG has been implemented operationally in many national and international dynamical models to provide validated radiative transfer for improving weather forecasts and enhancing the prediction of global climate change.

  19. Electrical Lumped Model Examination for Load Variation of Circulation System

    NASA Astrophysics Data System (ADS)

    Koya, Yoshiharu; Ito, Mitsuyo; Mizoshiri, Isao

    Modeling and analysis of the circulation system enables the characteristic decision of circulation system in the body to be made. So, many models of circulation system have been proposed. But, they are complicated because the models include a lot of elements. Therefore, we proposed a complete circulation model as a lumped electrical circuit, which is comparatively simple. In this paper, we examine the effectiveness of the complete circulation model as a lumped electrical circuit. We use normal, angina pectoris, dilated cardiomyopathy and myocardial infarction for evaluation of the ventricular contraction function.

  20. Anterior circulation model of subarachnoid hemorrhage in mice.

    PubMed

    Attia, Mohammed Sabri; Loch Macdonald, R

    2015-01-01

    Subarachnoid hemorrhage (SAH) remains one of the most morbid subtypes of stroke around the world and has been the focus of hemorrhagic stroke research for longer than five decades. Animal models have been instrumental in shaping the progress and advancement of SAH research, particularly models that allow for transgenic manipulation. The anterior circulation mouse model provides the research community with a rodent model that depicts very similar clinical findings of SAH; from the location of the hemorrhages to the secondary complications that arise after the hemorrhagic insult. The model allows for the recreation of clinically relevant findings such as large vessel vasospasm, oxidative stress, microcirculatory spasm and microthrombosis, and delayed neuronal injury - all of which appear in human cases of SAH. The model is also not technically demanding, is highly reproducible, and allows for an array of transgenic manipulation, which is essential for mechanistic investigations of the pathogenesis of SAH. The anterior circulation mouse model of SAH is one of a few models that are currently used in mice, and provides the research community with a relatively easy, reliable, and clinically relevant model of SAH - one that could be effectively be used to test for early brain injury (EBI) and delayed neurological injury after SAH.

  1. ADCIRC: An Advanced Three-Dimensional Circulation Model for Shelves, Coasts, and Estuaries. Report 1. Theory and Methodology of ADCIRC-2DDI and ADCIRC-3DL.

    DTIC Science & Technology

    1992-11-01

    approach is to solve transport equations !or the turbulent velocity correlations that make up the turbulent stresses (stress/flux models). However...j(80a) PO j PO P0 n= E1 )k Oj (80b) PO j =1Oi f. The dispersive terms are broken up into their components Duu, Duv and D,, (defined in Part II), and...approicimations in Equations 73 - 84 into Equation 67 and summing over the elements gives: eMu1{ n’ (’ TODAt ) < kl + Eht (<el + <C*,j + i ~~fe nel nel nel

  2. DETECTORS AND EXPERIMENTAL METHODS: Circulation model for water circulation and purification in a water Cerenkov detector

    NASA Astrophysics Data System (ADS)

    Lu, Hao-Qi; Yang, Chang-Gen; Wang, Ling-Yu; Xu, Ji-Lei; Wang, Rui-Guang; Wang, Zhi-Min; Wang, Yi-Fang

    2009-07-01

    Owing to its low cost and good transparency, highly purified water is widely used as a medium in large water Cerenkov detector experiments. The water circulation and purification system is usually needed to keep the water in good quality. In this work, a practical circulation model is built to describe the variation of the water resistivity in the circulation process and compared with the data obtained from a prototype experiment. The successful test of the model makes it useful in the future design and optimization of the circulation/purification system.

  3. Modeling biomass gasification in circulating fluidized beds

    NASA Astrophysics Data System (ADS)

    Miao, Qi

    In this thesis, the modeling of biomass gasification in circulating fluidized beds was studied. The hydrodynamics of a circulating fluidized bed operating on biomass particles were first investigated, both experimentally and numerically. Then a comprehensive mathematical model was presented to predict the overall performance of a 1.2 MWe biomass gasification and power generation plant. A sensitivity analysis was conducted to test its response to several gasifier operating conditions. The model was validated using the experimental results obtained from the plant and two other circulating fluidized bed biomass gasifiers (CFBBGs). Finally, an ASPEN PLUS simulation model of biomass gasification was presented based on minimization of the Gibbs free energy of the reaction system at chemical equilibrium. Hydrodynamics plays a crucial role in defining the performance of gas-solid circulating fluidized beds (CFBs). A 2-dimensional mathematical model was developed considering the hydrodynamic behavior of CFB gasifiers. In the modeling, the CFB riser was divided into two regions: a dense region at the bottom and a dilute region at the top of the riser. Kunii and Levenspiel (1991)'s model was adopted to express the vertical solids distribution with some other assumptions. Radial distributions of bed voidage were taken into account in the upper zone by using Zhang et al. (1991)'s correlation. For model validation purposes, a cold model CFB was employed, in which sawdust was transported with air as the fluidizing agent. A comprehensive mathematical model was developed to predict the overall performance of a 1.2 MWe biomass gasification and power generation demonstration plant in China. Hydrodynamics as well as chemical reaction kinetics were considered. The fluidized bed riser was divided into two distinct sections: (a) a dense region at the bottom of the bed where biomass undergoes mainly heterogeneous reactions and (b) a dilute region at the top where most of homogeneous

  4. Predictive models of circulating fluidized bed combustors

    SciTech Connect

    Gidaspow, D.

    1992-07-01

    Steady flows influenced by walls cannot be described by inviscid models. Flows in circulating fluidized beds have significant wall effects. Particles in the form of clusters or layers can be seen to run down the walls. Hence modeling of circulating fluidized beds (CFB) without a viscosity is not possible. However, in interpreting Equations (8-1) and (8-2) it must be kept in mind that CFB or most other two phase flows are never in a true steady state. Then the viscosity in Equations (8-1) and (8-2) may not be the true fluid viscosity to be discussed next, but an Eddy type viscosity caused by two phase flow oscillations usually referred to as turbulence. In view of the transient nature of two-phase flow, the drag and the boundary layer thickness may not be proportional to the square root of the intrinsic viscosity but depend upon it to a much smaller extent. As another example, liquid-solid flow and settling of colloidal particles in a lamella electrosettler the settling process is only moderately affected by viscosity. Inviscid flow with settling is a good first approximation to this electric field driven process. The physical meaning of the particulate phase viscosity is described in detail in the chapter on kinetic theory. Here the conventional derivation resented in single phase fluid mechanics is generalized to multiphase flow.

  5. Thermohaline circulation and its box models simulation

    NASA Astrophysics Data System (ADS)

    Bazyura, Kateryna; Polonsky, Alexander; Sannikov, Viktor

    2014-05-01

    Ocean Thermochaline circulation (THC) is the part of large-scale World Ocean circulation and one of the main climate system components. It is generated by global meridional density gradients, which are controlled by surface heat and freshwater fluxes. THC regulates climate variability on different timescales (from decades to thousands years) [Stocker (2000), Clark (2002)]. Study of paleoclimatic evidences of abrupt and dramatic changes in ocean-atmosphere system in the past (such as, Dansgaard-Oeschger and Heinrich events or Younger Dryas, see e.g., [Rahmstorf (2002), Alley & Clark(1999)]) shows that these events are connected with THC regimes. At different times during last 120,000 years, three THC modes have prevailed in the Atlantic. They can be labeled as stadial, interstadial and Heinrich modes or as cold, warm and off mode. THC collapse (or thermohaline catastrophe) can be one of the consequences of global warming (including modern anthropogenic climate changes occurring at the moment). The ideas underlying different box-model studies, possibility of thermochaline catastrophe in present and past are discussed in this presentation. Response of generalized four box model of North Atlantic thermohaline circulation [developing the model of Griffies & Tzippermann (1995)] on periodic, stochastic and linear forcing is studied in details. To estimate climatic parameters of the box model we used monthly salinity and temperature data of ECMWF operational Ocean Reanalysis System 3 (ORA-S3) and data from atmospheric NCEP/NCAR reanalysis on precipitation, and heat fluxes for 1959-2011. Mean values, amplitude of seasonal cycle, amplitudes and periods of typical interdecadal oscillations, white noise level, linear trend coefficients and their significance level were estimated for every hydrophysical parameter. In response to intense freshwater or heat forcing, THC regime can change resulting in thermohaline catastrophe. We analyze relevant thresholds of external forcing in

  6. Modeling the circulation of the Dead Sea

    NASA Astrophysics Data System (ADS)

    Brenner, Steve; Lensky, Nadav; Gertman, Isaac

    2015-04-01

    The Dead Sea is a hypersaline, terminal lake located at the lowest point on the land surface of the Earth. Its current level is more than 429 m below MSL, and due to a negative water balance (mainly anthropogenic), the lake level has been dropping at an average rate of more than 1 m/yr for more than 30 years. The mean salinity has also been steadily increasing and today is close to 280 psu. The region of the Dead Sea is a unique landscape that has important historical, cultural, and economic value and therefore such an extreme change of the lake has significant environmental and economic consequences. In recent years there has been a notable increase in observing and monitoring of the lake through continuous measurements from several fixed buoys as well as during quasi-regular cruises. In order to complement the measurements and improve our understanding of the dynamics of this unique lake a three dimensional circulation model is being developed. Previous modeling efforts were limited mainly to a one dimensional column model which was coupled to a comprehensive physio-chemical model and used for long term multi-decadal simulations. In this study the focus is on understanding the dynamical processes that control the lake-wide circulation on time scales ranging from days to seasons. The first step was to replace the equation of state with an equation appropriate for the hypersaline conditions, in addition to some minor tuning of the turbulence closure scheme. Results will be presented from preliminary simulations of the wind driven circulation in various seasons. A case study of a recent unusual winter flooding event, during which the lake level rose by more than 20 cm over a two month period, will also be presented. The model successfully simulated the observed transition from holomictic to meromictic conditions and epilimnion dilution during this event, as well as the restoration of holomictic conditions when the level started to drop again. The relationship

  7. Modeling the seasonal circulation in Massachusetts Bay

    USGS Publications Warehouse

    Signell, Richard P.; Jenter, Harry L.; Blumberg, Alan F.; ,

    1994-01-01

    An 18 month simulation of circulation was conducted in Massachusetts Bay, a roughly 35 m deep, 100??50 km embayment on the northeastern shelf of the United States. Using a variant of the Blumberg-Mellor (1987) model, it was found that a continuous 18 month run was only possible if the velocity field was Shapiro filtered to remove two grid length energy that developed along the open boundary due to mismatch in locally generated and climatologically forced water properties. The seasonal development of temperature and salinity stratification was well-represented by the model once ??-coordinate errors were reduced by subtracting domain averaged vertical profiles of temperature, salinity and density before horizontal differencing was performed. Comparison of modeled and observed subtidal currents at fixed locations revealed that the model performance varies strongly with season and distance from the open boundaries. The model performs best during unstratified conditions, and in the interior of the bay. The model performs poorest during stratified conditions and in the regions where the bay is driven predominantly by remote fluctuations from the Gulf of Maine.

  8. Ocean circulation modeling by use of radar altimeter data

    NASA Technical Reports Server (NTRS)

    Olbers, Dirk; Alpers, W.; Hasselmann, K.; Maier-Reimer, E.; Kase, R.; Krauss, W.; Siedler, G.; Willebrand, J.; Zahel, W.

    1991-01-01

    The project will investigate the use of radar altimetry (RA) data in the determination of the ocean circulation models. RA data will be used to verify prognostic experiments of the steady state and seasonal cycle of large-scale circulation models and the statistical steady state of eddy-resolving models. The data will serve as initial and update conditions in data assimilation experiments and as constraints in inverse calculations. The aim of the project is a better understanding of ocean physics, the determination and mapping of ocean currents, and a contribution to the establishment of ocean circulation models for climate studies. The goal of the project is to use satellite radar altimetry data for improving our knowledge of ocean circulation both in a descriptive sense and through the physics that govern the circulation state. The basic tool is a series of ocean circulation models. Depending on the model, different techniques will be applied to incorporate the RA data.

  9. Snow hydrology in a general circulation model

    NASA Technical Reports Server (NTRS)

    Marshall, Susan; Roads, John O.; Glatzmaier, Gary

    1994-01-01

    A snow hydrology has been implemented in an atmospheric general circulation model (GCM). The snow hydrology consists of parameterizations of snowfall and snow cover fraction, a prognostic calculation of snow temperature, and a model of the snow mass and hydrologic budgets. Previously, only snow albedo had been included by a specified snow line. A 3-year GCM simulation with this now more complete surface hydrology is compared to a previous GCM control run with the specified snow line, as well as with observations. In particular, the authors discuss comparisons of the atmospheric and surface hydrologic budgets and the surface energy budget for U.S. and Canadian areas. The new snow hydrology changes the annual cycle of the surface moisture and energy budgets in the model. There is a noticeable shift in the runoff maximum from winter in the control run to spring in the snow hydrology run. A substantial amount of GCM winter precipitation is now stored in the seasonal snowpack. Snow cover also acts as an important insulating layer between the atmosphere and the ground. Wintertime soil temperatures are much higher in the snow hydrology experiment than in the control experiment. Seasonal snow cover is important for dampening large fluctuations in GCM continental skin temperature during the Northern Hemisphere winter. Snow depths and snow extent show good agreement with observations over North America. The geographic distribution of maximum depths is not as well simulated by the model due, in part, to the coarse resolution of the model. The patterns of runoff are qualitatively and quantitatively similar to observed patterns of streamflow averaged over the continental United States. The seasonal cycles of precipitation and evaporation are also reasonably well simulated by the model, although their magnitudes are larger than is observed. This is due, in part, to a cold bias in this model, which results in a dry model atmosphere and enhances the hydrologic cycle everywhere.

  10. Snow hydrology in a general circulation model

    SciTech Connect

    Marshall, S. ); Roads, J.O. ); Glatzmaier, G. )

    1994-08-01

    A snow hydrology has been implemented in an atmospheric general circulation model (GCM). The snow hydrology consists of parameterizations of snowfall and snow cover fraction, a prognostic calculation of snow temperature, and a model of the snow mass and hydrologic budgets. Previously, only snow albedo had been included. A 3-year GCM simulation with this more complete surface hydrology is compared to a previous GCM control run with the specified snow line, as well as with observations. In particular, the authors discuss comparisons of the atmospheric and surface hydrologic budgets and the surface energy budget for U.S. and Canadian areas. The new snow hydrology changes the annual cycle of the surface moisture and energy budgets in the model. There is a noticeable shift in the runoff maximum from winter in the control run to spring in the snow hydrology run. A substantial amount of GCM winter precipitation is now stored in the seasonal snowpack. Snow cover also acts as an important insulating layer between the atmosphere and the ground. Wintertime soil temperatures are much higher in the snow, hydrology experiment than in the control experiment. Seasonal snow cover is important for dampening large fluctuations in GCM continental skin temperature during the Northern Hemisphere winter. Snow depths and snow extent show good agreement with observations over North America. The geographic distribution of maximum depths is not as well simulated by the model due, in part, to the coarse resolution of the model. The patterns of runoff are qualitatively and quantitatively similar to observed patterns of streamflow averaged over the continental United States. The seasonal cycles of precipitation and evaporation are also reasonably well simulated by the model, although their magnitudes are larger than is observed. This is due, in part, to a cold bias in this model, which results in a dry model atmosphere and enhances the hydrologic cycle everywhere. 52 refs., 13 figs., 5 tabs.

  11. Advanced Concept Modeling

    NASA Technical Reports Server (NTRS)

    Chaput, Armand; Johns, Zachary; Hodges, Todd; Selfridge, Justin; Bevirt, Joeben; Ahuja, Vivek

    2015-01-01

    Advanced Concepts Modeling software validation, analysis, and design. This was a National Institute of Aerospace contract with a lot of pieces. Efforts ranged from software development and validation for structures and aerodynamics, through flight control development, and aeropropulsive analysis, to UAV piloting services.

  12. Hemodynamic performance of the Fontan circulation compared with a normal biventricular circulation: a computational model study.

    PubMed

    Liang, Fuyou; Senzaki, Hideaki; Kurishima, Clara; Sughimoto, Koichi; Inuzuka, Ryo; Liu, Hao

    2014-10-01

    The physiological limitations of the Fontan circulation have been extensively addressed in the literature. Many studies emphasized the importance of pulmonary vascular resistance in determining cardiac output (CO) but gave little attention to other cardiovascular properties that may play considerable roles as well. The present study was aimed to systemically investigate the effects of various cardiovascular properties on clinically relevant hemodynamic variables (e.g., CO and central venous pressure). To this aim, a computational modeling method was employed. The constructed models provided a useful tool for quantifying the hemodynamic effects of any cardiovascular property of interest by varying the corresponding model parameters in model-based simulations. Herein, the Fontan circulation was studied compared with a normal biventricular circulation so as to highlight the unique characteristics of the Fontan circulation. Based on a series of numerical experiments, it was found that 1) pulmonary vascular resistance, ventricular diastolic function, and systemic vascular compliance play a major role, while heart rate, ventricular contractility, and systemic vascular resistance play a secondary role in the regulation of CO in the Fontan circulation; 2) CO is nonlinearly related to any single cardiovascular property, with their relationship being simultaneously influenced by other cardiovascular properties; and 3) the stability of central venous pressure is significantly reduced in the Fontan circulation. The findings suggest that the hemodynamic performance of the Fontan circulation is codetermined by various cardiovascular properties and hence a full understanding of patient-specific cardiovascular conditions is necessary to optimize the treatment of Fontan patients.

  13. COMPUTATIONAL MODELING OF CIRCULATING FLUIDIZED BED REACTORS

    SciTech Connect

    Ibrahim, Essam A

    2013-01-09

    Details of numerical simulations of two-phase gas-solid turbulent flow in the riser section of Circulating Fluidized Bed Reactor (CFBR) using Computational Fluid Dynamics (CFD) technique are reported. Two CFBR riser configurations are considered and modeled. Each of these two riser models consist of inlet, exit, connecting elbows and a main pipe. Both riser configurations are cylindrical and have the same diameter but differ in their inlet lengths and main pipe height to enable investigation of riser geometrical scaling effects. In addition, two types of solid particles are exploited in the solid phase of the two-phase gas-solid riser flow simulations to study the influence of solid loading ratio on flow patterns. The gaseous phase in the two-phase flow is represented by standard atmospheric air. The CFD-based FLUENT software is employed to obtain steady state and transient solutions for flow modulations in the riser. The physical dimensions, types and numbers of computation meshes, and solution methodology utilized in the present work are stated. Flow parameters, such as static and dynamic pressure, species velocity, and volume fractions are monitored and analyzed. The differences in the computational results between the two models, under steady and transient conditions, are compared, contrasted, and discussed.

  14. GPU Developments for General Circulation Models

    NASA Astrophysics Data System (ADS)

    Appleyard, Jeremy; Posey, Stan; Ponder, Carl; Eaton, Joe

    2014-05-01

    Current trends in high performance computing (HPC) are moving towards the use of graphics processing units (GPUs) to achieve speedups through the extraction of fine-grain parallelism of application software. GPUs have been developed exclusively for computational tasks as massively-parallel co-processors to the CPU, and during 2013 an extensive set of new HPC architectural features were developed in a 4th generation of NVIDIA GPUs that provide further opportunities for GPU acceleration of general circulation models used in climate science and numerical weather prediction. Today computational efficiency and simulation turnaround time continue to be important factors behind scientific decisions to develop models at higher resolutions and deploy increased use of ensembles. This presentation will examine the current state of GPU parallel developments for stencil based numerical operations typical of dynamical cores, and introduce new GPU-based implicit iterative schemes with GPU parallel preconditioning and linear solvers based on ILU, Krylov methods, and multigrid. Several GCMs show substantial gain in parallel efficiency from second-level fine-grain parallelism under first-level distributed memory parallel through a hybrid parallel implementation. Examples are provided relevant to science-scale HPC practice of CPU-GPU system configurations based on model resolution requirements of a particular simulation. Performance results compare use of the latest conventional CPUs with and without GPU acceleration. Finally a forward looking discussion is provided on the roadmap of GPU hardware, software, tools, and programmability for GCM development.

  15. Regional climates in the GISS global circulation model - Synoptic-scale circulation

    NASA Technical Reports Server (NTRS)

    Hewitson, B.; Crane, R. G.

    1992-01-01

    A major weakness of current general circulation models (GCMs) is their perceived inability to predict reliably the regional consequences of a global-scale change, and it is these regional-scale predictions that are necessary for studies of human-environmental response. For large areas of the extratropics, the local climate is controlled by the synoptic-scale atmospheric circulation, and it is the purpose of this paper to evaluate the synoptic-scale circulation of the Goddard Institute for Space Studies (GISS) GCM. A methodology for validating the daily synoptic circulation using Principal Component Analysis is described, and the methodology is then applied to the GCM simulation of sea level pressure over the continental United States (excluding Alaska). The analysis demonstrates that the GISS 4 x 5 deg GCM Model II effectively simulates the synoptic-scale atmospheric circulation over the United States. The modes of variance describing the atmospheric circulation of the model are comparable to those found in the observed data, and these modes explain similar amounts of variance in their respective datasets. The temporal behavior of these circulation modes in the synoptic time frame are also comparable.

  16. Enceladus' Interior: A Liquid Circulation Model

    NASA Astrophysics Data System (ADS)

    Matson, Dennis L.; Johnson, Torrence; Lunine, Jonathan; Castillo-Rogez, Julie

    We are studying a model for Enceladus' interior in which the water, gas, dust and heat are supplied to the plumes by a relatively deeply circulating brine solution. Data indicates such a source for the erupting material. On the basis of ammonia in the plume gas Waite et al. [1] suggested that the jets might originate from a liquid water region under Enceladus' icy surface. Postberg et al. [2] noted that the presence of ". . . grains that are rich in sodium salts (0.5-2 percent by mass). . . can arise only if the plumes originate from liquid water." Waite et al. [1] also regard the some of the plume chemicals as evidence for interactions with an ice layer presumably overlying the liquid water reservoir. They suggest that this could be in the form of dissociation of clathrate hydrates [3]. Additionally, there is a large heat flow of more than 15 GW [4, 5] coming out of Enceladus' south polar region. We consider a model that brings heat and chemical species up to the surface from a reservoir or "ocean" located below the ice crust that may be many tens of kilometers thick. Water transits to the surface via vertical conduits. The Cassini INMS data suggest that the water has a relatively large gas content of order a few percent. As the water travels upward and the pressure is released, exolving gases form bubbles. Since the bubbly liquid is less dense than the ice, it moves upward. (This part of the model is a variant of the "Perrier Ocean" Europa model of Crawford and Stevenson [6]. A similar model was studied for Ganymede by Murchie and Head [7].) Postberg et al. [2] model the plume eruptions that result from the water, gases, salts, and other chemicals that our circulation model provides. In the near-surface reservoir feeding the plumes, bubbles reaching the surface of the water pop and throw a very fine spray. Some of these very small droplets of brine exit with the plume gas and provide the observed salt-rich dust particles [2]. Much of the water-borne heat is

  17. A Model for Library Book Circulations Incorporating Loan Periods.

    ERIC Educational Resources Information Center

    Burrell, Quentin L.; Fenton, Michael R.

    1994-01-01

    Proposes and explains a modification of the mixed Poisson model for library circulations which takes into account the periods when a book is out on loan and therefore unavailable for borrowing. Highlights include frequency of circulation distributions; negative binomial distribution; and examples of the model at two universities. (Contains 34…

  18. Diversity of Planetary Atmospheric Circulations and Climates in a Simplified General Circulation Model

    NASA Astrophysics Data System (ADS)

    Wang, Yixiong; Read, Peter

    2014-04-01

    The parametric dependence of terrestrial planetary atmospheric circulations and climates on characteristic parameters is studied. A simplified general circulation model-PUMA is employed to investigate the dynamic effects of planetary rotation rate and equator-to-pole temperature difference on the circulation and climate of terrestrial planetary atmospheres. Five different types of circulation regime are identified by mapping the experimental results in a 2-D parameter space defined by thermal Rossby number and frictional Taylor number. The effect of the transfer and redistribution of radiative energy is studied by building up a new two-band semi-gray radiative-convective scheme, which is capable of modelling greenhouse and anti-greenhouse effects while keeping the tunable parameters as few as possible. The results will provide insights into predicting the habitability of terrestrial exoplanets.

  19. ADCIRC: An advanced three-dimensional circulation model for shelves, coasts, and estuaries. Report 3. Development of a tidal constituent database for the western north Atlantic and Gulf of Mexico. Technical report

    SciTech Connect

    Westerink, J.J.; Luettich, R.A.; Scheffner, N.

    1993-06-01

    This report describes the application of model ADCIRC-2DDI, a two-dimensional, depth-integrated, finite-element-based hydrodynamic circulation code, to the western North Atlantic, Gulf of Mexico and Caribbean Sea in order to develop a tidal constituent database. Issues that are emphasized in the development of the Western North Atlantic Tidal (WNAT) model include the definition of hydrodynamically simple open ocean boundaries; the use of large domains; the importance of a high degree of grid resolution in coastal regions; and the use of finite element meshes with highly varying nodal densities in order to minimize the size of the discrete problem. The development of an optimal graded finite element mesh is based on regular and graded grid convergence studies using an M2 tidal forcing function on the boundary and within the domain. The optimal graded mesh is then forced for eight diurnal and semidiurnal astronomical tidal constituents (K1, O1, PI, Ql, M2, S2, N2, and K2) on the open ocean boundary by coupling to Schwiderski's (1979; 1981 a-g) global model results as well as within the interior domain using a tidal potential forcing function. The structure of the various tides is examined and results are compared to field data at 77 stations.... Bottom stress, Finite element method, Three-dimensional model, Circulation model, Hydrodynamic model, Two-dimensional model, Direct stress solution, Numerical model.

  20. What is Required to Model the Global Ocean Circulation?

    DTIC Science & Technology

    2011-01-01

    simulating the mean circulation with studies suggesting that horizontal resolutions around 1/10° are sufficient [Smith, et al ., 2000; Hurlburt and Hogan...depths greater than 3,000 m) [Scott, et al ., 2010]. The eddy-driven mean abyssal circulation, which is constrained by the topography, can steer the mean...2000; Hurlburt, et al ., 2008]. Recent model studies suggest that a strong eddy-driven mean abyssal circulation is sufficient to obtain a realistic Gulf

  1. Geochemistry and Models of Mantle Circulation

    NASA Astrophysics Data System (ADS)

    Hofmann, A. W.

    1989-07-01

    Geochemical data help to constrain the sizes of identifiable reservoirs within the framework of models of layered or whole-mantle circulation, and they identify the sources of the circulating heterogeneities as mainly crustal and/or lithospheric, but they do not decisively distinguish between different types of circulation. The mass balance between crust, depleted mantle and undepleted mantle based on 143Nd/144Nd, Nb/U and Ce/Pb, and the concentrations of very highly incompatible elements Ba, Rb, Th, U, and K, shows that ca. 25-70% (by mass) of depleted mantle balances the trace element and isotopic abundances of the continental crust. This mass balance reflects the actual proportions of mantle reservoirs only if there are no additional unidentified reservoirs. Evidence on the nature and ages of different source reservoirs comes from the geochemical fingerprints of basalts extruded at mid-ocean ridges and oceanic islands. Consideration of Nd and He isotopes alone indicates that ocean island basalts (OIBS) may be derived from a relatively undepleted portion of the mantle. This has in the past provided a geochemical rationale for a two-layer model consisting of an upper depleted and a lower undepleted (`primitive') mantle layer. However, Pb-isotopic ratios, and Nb/U and Ce/Pb concentration ratios demonstrate that most or all OIB source reservoirs are definitely not primitive. Models consistent with this evidence postulate recycling of oceanic crust and lithosphere or subcontinental lithosphere. Recycling is a natural consequence of mantle convection. This cannot be said for some other models such as those requiring large-scale vertical metasomatism beneath OIB source regions. Unlike other trace elements, Nb, Ta, and Pb discriminate sharply between continental and oceanic crust-forming processes. Because of this, the primitive mantle value of Nb/U = 30 (Ce/Pb = 9) has been fractionated into a continental crustal Nb/U = 12 (Ce/Pb = 4) and a residual-mantle (MORB (mid

  2. Model-free adaptive control of supercritical circulating fluidized-bed boilers

    SciTech Connect

    Cheng, George Shu-Xing; Mulkey, Steven L

    2014-12-16

    A novel 3-Input-3-Output (3.times.3) Fuel-Air Ratio Model-Free Adaptive (MFA) controller is introduced, which can effectively control key process variables including Bed Temperature, Excess O2, and Furnace Negative Pressure of combustion processes of advanced boilers. A novel 7-input-7-output (7.times.7) MFA control system is also described for controlling a combined 3-Input-3-Output (3.times.3) process of Boiler-Turbine-Generator (BTG) units and a 5.times.5 CFB combustion process of advanced boilers. Those boilers include Circulating Fluidized-Bed (CFB) Boilers and Once-Through Supercritical Circulating Fluidized-Bed (OTSC CFB) Boilers.

  3. An elementary model of money circulation

    NASA Astrophysics Data System (ADS)

    Pokrovskii, Vladimir N.; Schinckus, Christophe

    2016-12-01

    This paper investigates money circulation for a system, consisting of a production system, the government, a central bank, commercial banks and many customers of the commercial banks. A set of equations for the system is written; the theory determines the main features of interaction between production and money circulation. Investigation of the equations in a steady-state situation reveals some relationship among output of the production system and monetary variables. The relation of quantity theory of money is confirmed, whereas a new concept of the efficiency of the system is introduced.

  4. THE ESC COMPUTERIZED CIRCULATION SYSTEM MODEL II.

    ERIC Educational Resources Information Center

    SHAWVER, W.; STRAIN, P.M.

    A NEW CIRCULATION SYSTEM NOW IN USE AT THE ELECTRONICS SYSTEMS CENTER (ESC) LIBRARY, PART OF INTERNATIONAL BUSINESS MACHINES CORPORATION, IS BASED UPON A PREVIOUS SYSTEM WHICH USED TABULATING CARDS, UNIT RECORD MACHINES, AND A SMALL COMPUTER. THE NEW SYSTEM IS A TRANSACTION CARD SYSTEM, IN WHICH ONE BASIC TYPE OF CARD FORMAT IS USED FOR CHARGING,…

  5. Advances in circulating tumor cells (ACTC): from basic research to clinical practice

    PubMed Central

    2013-01-01

    The first 'Advances in Circulating Tumor Cells (ACTC): from Basic Research to Clinical Practice' meeting was held in Athens, Greece, September 26–29, 2012 (abstracts, presentations and a more detailed meeting report are freely available online: http://www.actc2012.org). We summarize in this report most major findings presented and the main conclusions derived during the expert panel sessions. PMID:24314311

  6. Stochastic resonance on a global atmospheric circulation model

    NASA Astrophysics Data System (ADS)

    Perez-Munuzuri, V.; Deza, R.; Fraedrich, K.; Kirk, E.; Lunkeit, F.

    2003-04-01

    Seeking for alternative sources of the observed climatic variability, and in the spirit of both classic (Nicolis, 1982; Benzi et al., 1982) and recent work (Ganopolski and Rahmstorg, 2002; Vélez-Belch&{acute;i} et al., 2001), we have added a space-independent, Gaussian and uncorrelated stochastic perturbation with amplitude eta, to the temperature equation of a simplified atmospheric global circulation model, the so-called PUMA (Portable University Model of the Atmosphere) (Frisius et al., 1998; Pérez-Muñuzuri et al., 2003). In the latter model, diabatic processes are parameterized by a Newtonian cooling term with typical timescale τ_c, whose reference temperature profile T_R(λ,μ,σ;t) (representing the ``equilibrium'' profile induced by solar heating) is given by T_R=overline{T}_R(λ,μ,σ)+ hat{T}_R \\cos[(2pi/Tac)t+Pac]. We show that the time averages of several forecasting magnitudes (like temperature and horizontal vorticity) at a point on the 300 hPa surface, undergo a non-monotonic behavior with regard to eta. Moreover, the normalized variance R=sqrt{-^2}/ of the interval t_p between the passage at the point of cyclonic and anticyclonic circulation regions exhibits an ``anticoherence resonance'' effect, thus maximizing climatic variability for some intermediate value of eta. A theoretical explanation is advanced in terms of activated processes with competing time scales. begin{itemize} C. Nicolis, Tellus 34, 1 (1982); Benzi et al., Tellus 34, 10 (1982). A. Ganopolski and S. Rahmstorg, Phys. Rev. Lett. 88, 038501 (2002); P. Vélez-Belch&{acute;i} et al., Geophys. Res. Lett. 28, 2053 (2001). T. Frisius, F. Lunkeit, K. Fraedrich and I.N. James. Q.J.R. Meteorol. Soc. 124, 1019 (1998); V. Pérez-Muñuzuri et al. Nonlin. Proc. Geophys. (submitted) (2003).

  7. Systemic modelling of human bioenergetics and blood circulation.

    PubMed

    Lim, K M; Yang, S-H; Shim, E B

    2012-10-01

    This work reviews the main aspects of human bioenergetics and the dynamics of the cardiovascular system, with emphasis on modelling their physiological characteristics. The methods used to study human bioenergetics and circulation dynamics, including the use of mathematical models, are summarised. The main characteristics of human bioenergetics, including mitochondrial metabolism and global energy balance, are first described, and the systemic aspects of blood circulation and related physiological issues are introduced. The authors also discuss the present status of studies of human bioenergetics and blood circulation. Then, the limitations of the existing studies are described in an effort to identify directions for future research towards integrated and comprehensive modelling. This review emphasises that a multi-scale and multi-physical approach to bioenergetics and blood circulation that considers multiple scales and physiological factors are necessary for the appropriate clinical application of computational models.

  8. Correcting circulation biases in a lower-resolution global general circulation model with data assimilation

    NASA Astrophysics Data System (ADS)

    Canter, Martin; Barth, Alexander; Beckers, Jean-Marie

    2016-12-01

    In this study, we aim at developing a new method of bias correction using data assimilation. This method is based on the stochastic forcing of a model to correct bias by directly adding an additional source term into the model equations. This method is presented and tested first with a twin experiment on a fully controlled Lorenz '96 model. It is then applied to the lower-resolution global circulation NEMO-LIM2 model, with both a twin experiment and a real case experiment. Sea surface height observations are used to create a forcing to correct the poorly located and estimated currents. Validation is then performed throughout the use of other variables such as sea surface temperature and salinity. Results show that the method is able to consistently correct part of the model bias. The bias correction term is presented and is consistent with the limitations of the global circulation model causing bias on the oceanic currents.

  9. Correcting circulation biases in a lower-resolution global general circulation model with data assimilation

    NASA Astrophysics Data System (ADS)

    Canter, Martin; Barth, Alexander; Beckers, Jean-Marie

    2017-02-01

    In this study, we aim at developing a new method of bias correction using data assimilation. This method is based on the stochastic forcing of a model to correct bias by directly adding an additional source term into the model equations. This method is presented and tested first with a twin experiment on a fully controlled Lorenz '96 model. It is then applied to the lower-resolution global circulation NEMO-LIM2 model, with both a twin experiment and a real case experiment. Sea surface height observations are used to create a forcing to correct the poorly located and estimated currents. Validation is then performed throughout the use of other variables such as sea surface temperature and salinity. Results show that the method is able to consistently correct part of the model bias. The bias correction term is presented and is consistent with the limitations of the global circulation model causing bias on the oceanic currents.

  10. Physiologically Based Pharmacokinetic Model for Long-Circulating Inorganic Nanoparticles.

    PubMed

    Liang, Xiaowen; Wang, Haolu; Grice, Jeffrey E; Li, Li; Liu, Xin; Xu, Zhi Ping; Roberts, Michael S

    2016-02-10

    A physiologically based pharmacokinetic model was developed for accurately characterizing and predicting the in vivo fate of long-circulating inorganic nanoparticles (NPs). This model is built based on direct visualization of NP disposition details at the organ and cellular level. It was validated with multiple data sets, indicating robust inter-route and interspecies predictive capability. We suggest that the biodistribution of long-circulating inorganic NPs is determined by the uptake and release of NPs by phagocytic cells in target organs.

  11. Effects of cumulus convection on the simulated monsoon circulation in a general circulation model

    SciTech Connect

    Zhang, Guang Jun )

    1994-09-01

    The effect of cumulus convection on the Asian summer monsoon circulation is investigated, using a general circulation model. Two simulations for the summer months (June, July, and August) are performed, one parameterizing convection using a mass flux scheme and the other without convective parameterization. The results show that convection has significant effects on the monsoon circulation and its associated precipitation. In the simulation with the mass flux convective parameterization, precipitation in the western Pacific is decreased, together with a decrease in surface evaporation and wind speed. In the indian monsoon region it is almost the opposite. Comparison with a simulation using moist convective adjustment to parameterize convection shows that the monsoon circulation and precipitation distribution in the no-convection simulation are very similar to those in the simulation with moist convective adjustment. The difference in the large-scale circulation with and without convective parameterization is interpreted in terms of convective stabilization of the atmosphere by convection, using dry and moist static energy budgets. It is shown that weakening of the low-level convergence in the western Pacific in the simulation with convection is closely associated with the stabilization of the atmosphere by convection, mostly through drying of the lower troposphere; changes in low-level convergence lead to changes in precipitation. The precipitation increase in the Indian monsoon can be explained similarly. 29 refs., 12 figs.

  12. Advanced Chemistry Basins Model

    SciTech Connect

    William Goddard; Mario Blanco; Lawrence Cathles; Paul Manhardt; Peter Meulbroek; Yongchun Tang

    2002-11-10

    The DOE-funded Advanced Chemistry Basin model project is intended to develop a public domain, user-friendly basin modeling software under PC or low end workstation environment that predicts hydrocarbon generation, expulsion, migration and chemistry. The main features of the software are that it will: (1) afford users the most flexible way to choose or enter kinetic parameters for different maturity indicators; (2) afford users the most flexible way to choose or enter compositional kinetic parameters to predict hydrocarbon composition (e.g., gas/oil ratio (GOR), wax content, API gravity, etc.) at different kerogen maturities; (3) calculate the chemistry, fluxes and physical properties of all hydrocarbon phases (gas, liquid and solid) along the primary and secondary migration pathways of the basin and predict the location and intensity of phase fractionation, mixing, gas washing, etc.; and (4) predict the location and intensity of de-asphaltene processes. The project has be operative for 36 months, and is on schedule for a successful completion at the end of FY 2003.

  13. Advanced geothermal hydraulics model -- Phase 1 final report, Part 2

    SciTech Connect

    W. Zheng; J. Fu; W. C. Maurer

    1999-07-01

    An advanced geothermal well hydraulics model (GEODRIL) is being developed to accurately calculate bottom-hole conditions in these hot wells. In Phase 1, real-time monitoring and other improvements were added to GEODRIL. In Phase 2, GEODRIL will be integrated into Marconi's Intelligent Drilling Monitor (IDM) that will use artificial intelligence to detect lost circulation, fluid influxes and other circulation problems in geothermal wells. This software platform has potential for significantly reducing geothermal drilling costs.

  14. ADVANCED MIXING MODELS

    SciTech Connect

    Lee, S; Richard Dimenna, R; David Tamburello, D

    2008-11-13

    (50,000 to 300,000) with a relative standard deviation of {+-} 11.83%. An improved correlation including the effect of circulation time was proposed by Grenville and Tilton [11] via a better fit of mixing time data for turbulent jet mixing under a wider range of jet Reynolds numbers (50,000 to 300,000). The circulation time was defined as the liquid volume divided by the entrained flow rate. They assumed that the mixing rate at the end of the jet length controls the mixing time for the entire tank by estimating the kinetic energy dissipation rate as discussed earlier. They predicted that for a given volume, an optimum geometry exists for a mixing vessel, allowing a desired mixing time to be achieved for a minimum power input. The current work will compare their correlation of the jet mixing time with CFD modeling results for their experimental tanks in an attempt to achieve a fundamental understanding of the turbulent jet mixing and to establish mixing indicators.

  15. Calibrating the ECCO ocean general circulation model using Green's functions

    NASA Technical Reports Server (NTRS)

    Menemenlis, D.; Fu, L. L.; Lee, T.; Fukumori, I.

    2002-01-01

    Green's functions provide a simple, yet effective, method to test and calibrate General-Circulation-Model(GCM) parameterizations, to study and quantify model and data errors, to correct model biases and trends, and to blend estimates from different solutions and data products.

  16. Cloud Feedback in Atmospheric General Circulation Models: An Update

    NASA Technical Reports Server (NTRS)

    Cess, R. D.; Zhang, M. H.; Ingram, W. J.; Potter, G. L.; Alekseev, V.; Barker, H. W.; Cohen-Solal, E.; Colman, R. A.; Dazlich, D. A.; DelGenio, A. D.; Dix, M. R.; Dymnikov, V.; Esch, M.; Fowler, L. D.; Fraser, J. R.; Galin, V.; Gates, W. L.; Hack, J. J.; Kiehl, J. T.; LeTreut, H.

    1996-01-01

    Six years ago, we compared the climate sensitivity of 19 atmospheric general circulation models and found a roughly threefold variation among the models; most of this variation was attributed to differences in the models' depictions of cloud feedback. In an update of this comparison, current models showed considerably smaller differences in net cloud feedback, with most producing modest values. There are, however, substantial differences in the feedback components, indicating that the models still have physical disagreements.

  17. Optimal control of CPR procedure using hemodynamic circulation model

    DOEpatents

    Lenhart, Suzanne M.; Protopopescu, Vladimir A.; Jung, Eunok

    2007-12-25

    A method for determining a chest pressure profile for cardiopulmonary resuscitation (CPR) includes the steps of representing a hemodynamic circulation model based on a plurality of difference equations for a patient, applying an optimal control (OC) algorithm to the circulation model, and determining a chest pressure profile. The chest pressure profile defines a timing pattern of externally applied pressure to a chest of the patient to maximize blood flow through the patient. A CPR device includes a chest compressor, a controller communicably connected to the chest compressor, and a computer communicably connected to the controller. The computer determines the chest pressure profile by applying an OC algorithm to a hemodynamic circulation model based on the plurality of difference equations.

  18. Model-free adaptive control of advanced power plants

    DOEpatents

    Cheng, George Shu-Xing; Mulkey, Steven L.; Wang, Qiang

    2015-08-18

    A novel 3-Input-3-Output (3.times.3) Model-Free Adaptive (MFA) controller with a set of artificial neural networks as part of the controller is introduced. A 3.times.3 MFA control system using the inventive 3.times.3 MFA controller is described to control key process variables including Power, Steam Throttle Pressure, and Steam Temperature of boiler-turbine-generator (BTG) units in conventional and advanced power plants. Those advanced power plants may comprise Once-Through Supercritical (OTSC) Boilers, Circulating Fluidized-Bed (CFB) Boilers, and Once-Through Supercritical Circulating Fluidized-Bed (OTSC CFB) Boilers.

  19. Modeling of Antarctic sea ice in a general circulation model

    SciTech Connect

    Wu, Xingren; Budd, W.F.; Simmonds, I.

    1997-04-01

    A dynamic-thermodynamic sea ice model is developed and coupled with the Melbourne University general circulation model to simulate the seasonal cycle of the Antarctic sea ice distributions The model is efficient, rapid to compute, and useful for a range of climate studies. The thermodynamic part of the sea ice model is similar to that developed by Parkinson and Washington, the dynamics contain a simplified ice rheology that resists compression. The thermodynamics is based on energy conservation at the top surface of the ice/snow, the ice/water interface, and the open water area to determine the ice formation, accretion, and ablation. A lead parameterization is introduced with an effective partitioning scheme for freezing between and under the ice floes. The dynamic calculation determines the motion of ice, which is forced with the atmospheric wind, taking account of ice resistance and rafting. The simulated sea ice distribution compares reasonably well with observations. The seasonal cycle of ice extent is well simulated in phase as well as in magnitude. Simulated sea ice thickness and concentration are also in good agreement with observations over most regions and serve to indicate the importance of advection and ocean drift in the determination of the sea ice distribution. 64 refs., 15 figs., 2 tabs.

  20. Stratospheric General Circulation with Chemistry Model (SGCCM)

    NASA Technical Reports Server (NTRS)

    Rood, Richard B.; Douglass, Anne R.; Geller, Marvin A.; Kaye, Jack A.; Nielsen, J. Eric; Rosenfield, Joan E.; Stolarski, Richard S.

    1990-01-01

    In the past two years constituent transport and chemistry experiments have been performed using both simple single constituent models and more complex reservoir species models. Winds for these experiments have been taken from the data assimilation effort, Stratospheric Data Analysis System (STRATAN).

  1. Adaptation of a general circulation model to ocean dynamics

    NASA Technical Reports Server (NTRS)

    Turner, R. E.; Rees, T. H.; Woodbury, G. E.

    1976-01-01

    A primitive-variable general circulation model of the ocean was formulated in which fast external gravity waves are suppressed with rigid-lid surface constraint pressires which also provide a means for simulating the effects of large-scale free-surface topography. The surface pressure method is simpler to apply than the conventional stream function models, and the resulting model can be applied to both global ocean and limited region situations. Strengths and weaknesses of the model are also presented.

  2. Continued Development and Application of Circulation Control Pneumatic Technology to Advanced Transport Aircraft

    NASA Technical Reports Server (NTRS)

    Englar, Robert J.

    1998-01-01

    Personnel of the Georgia Tech Research Institute (GTRI) Aerospace and Transportation Lab have completed a four-year grant program to develop and evaluate the pneumatic aerodynamic technology known as Circulation Control (CC) or Circulation Control Wing (CCW) for advanced transport aircraft. This pneumatic technology, which employs low-level blowing from tangential slots over round or near-round trailing edges of airfoils, greatly augments the circulation around a lifting or control surface and thus enhances the aerodynamic forces and moments generated by that surface. Two-dimensional force augmentations as high as 80 times the input blowing momentum coefficient have been recorded experimentally for these blown devices, thus providing returns of 8000% on the jet momentum expended. A further benefit is the absence of moving parts such as mechanical flaps, slats, spoilers, ailerons, elevators and rudders from these pneumatic surfaces, or the use of only very small, simple, blown aerodynamic surfaces on synergistic designs which integrate the lift, drag and control surfaces. The application of these devices to advanced aircraft can offer significant benefits in their performance, efficiency, simplicity, reliability, economic cost of operation, noise reduction, and safety of flight. To further develop and evaluate this potential, this research effort was conducted by GTRI under grant for the NASA Langley Research Center, Applied Aerodynamics Division, Subsonic Aerodynamics Branch, between June 14, 1993 and May 31, 1997.

  3. Travel-time based model of bioremediation using circulation wells.

    PubMed

    Cirpka, O A; Kitanidis, P K

    2001-01-01

    Vertical circulation wells can efficiently provide microorganisms with substrates needed for enhanced bioremediation. We present a travel-time based approach for modeling bioreactive transport in a flow field caused by a series of circulation wells. Mixing within the aquifer is due to the differences in sorption behavior of the reactants. Neglecting local dispersion, transport simplifies to a single one-dimensional problem with constant coefficients for each well. Recirculation is characterized by the discharge densities over travel time. We apply the model to the stimulation of cometabolic dechlorination of trichloroethene (TCE) by alternate injection of oxygen and toluene into the circulation wells. Mixing within the wells can be minimized by interposing sufficiently long breaks between the oxygen and toluene pulses. In our simulation, the proposed injection scheme stimulates biomass growth without risking biofouling of the aquifer.

  4. Modelling the shelf circulation off eastern Tasmania

    NASA Astrophysics Data System (ADS)

    Oliver, Eric C. J.; Herzfeld, Mike; Holbrook, Neil J.

    2016-11-01

    The marine waters across Tasmanian's eastern continental shelf are biologically productive and home to economically important fisheries and aquaculture industries. However, the marine climate there is poorly understood. We use a high-resolution (∼2 km in the horizontal), three-dimensional ocean model for eastern Tasmania (ETAS) to examine the simulated mean state and seasonal cycle of temperature, salinity and three-dimensional flow field, and the evaluation of daily model outputs against in situ and remote observations for the 1993-2014 period. We also use the model to examine the roles of river input and tidal forcing. The model is evaluated against remotely-sensed sea surface temperature and in-situ observations of sea level and subsurface temperature, salinity, and currents. The mean state demonstrates the influence of two well-known boundary currents (the East Australian Current, EAC, and the Zeehan Current, ZC) as well as the effects of local freshwater input from river runoff. The EAC is dominant in summer and the ZC in winter; the influence of the EAC also increases northwards and in the offshore direction. In addition, the model indicates the presence of a semi-permanent subsurface (50-100 m depth) northward flow trapped near the coast. Cool freshwater runoff from the Derwent and Huon Rivers directly impacts the temperature and salinity in their estuaries but has little influence further across the shelf. Tidal forcing impacts the mean state through tide-river interactions which flush Frederick Henry Bay and Norfolk Bay with freshwater. Tidal forcing also impacts the variability of temperature all along the coastline, most likely due to changes in the turbulent mixing near to the coast. The ETAS model output data are available as a high-resolution representation of the mean state, seasonal variations, and interannual variability of Tasmania's eastern continental shelf marine climate.

  5. Interactions Between the Thermohaline Circulation and Tropical Atlantic SST in a Coupled General Circulation Model

    NASA Technical Reports Server (NTRS)

    Miller, Ron; Jiang, Xing-Jian; Travis, Larry (Technical Monitor)

    2001-01-01

    Tropical Atlantic SST shows a (statistically well-defined) decadal time scale in a 104-year simulation of unforced variability by a coupled general circulation model (CGCM). The SST anomalies superficially resemble observed Tropical Atlantic variability (TAV), and are associated with changes in the atmospheric circulation. Brazilian rainfall is modulated with a decadal time scale, along with the strength of the Atlantic trade winds, which are associated with variations in evaporation and the net surface heat flux. However, in contrast to observed tropical Atlantic variability, the trade winds damp the associated anomalies in ocean temperature, indicating a negative feedback. Tropical SST anomalies in the CGCM, though opposed by the surface heat flux, are advected in from the Southern Hemisphere mid-latitudes. These variations modulate the strength of the thermohaline circulation (THC): warm, salty anomalies at the equator sink drawing cold, fresh mid-latitude water. Upon reaching the equator, the latter inhibit vertical overturning and advection from higher latitudes, which allows warm, salty anomalies to reform, returning the cycle to its original state. Thus, the cycle results from advection of density anomalies and the effect of these anomalies upon the rate of vertical overturning and surface advection. This decadal modulation of Tropical Atlantic SST and the thermohaline circulation is correlated with ocean heat transport to the Northern Hemisphere high latitudes and Norwegian Sea SST. Because of the central role of equatorial convection, we question whether this mechanism is present in the current climate, although we speculate that it may have operated in palaeo times, depending upon the stability of the tropical water column.

  6. Assimilating Data into a Circulation Model

    DTIC Science & Technology

    2002-09-30

    Data assimilation methods provide a formal means for combining models with measurements to generate solutions that constitute a best fit to all relevant...other researchers involved in NCEX-related projects. Also, knowledge gained about the assimilation methods used here can benefit the ongoing NOPP

  7. Assimilating Data into a Circulation Model

    DTIC Science & Technology

    2003-09-30

    video observations, such as surf zone width and energy dissipation. APPROACH Data assimilation methods provide a formal means for combining...knowledge gained about the assimilation methods used here can benefit the ongoing NOPP project (Lead P.I. J.T. Kirby) “Development and Verification of a Comprehensive Community Model for Physical Processes in the Nearshore Ocean”. 7

  8. Circulation-based Modeling of Gravity Currents

    NASA Astrophysics Data System (ADS)

    Meiburg, E. H.; Borden, Z.

    2013-05-01

    Atmospheric and oceanic flows driven by predominantly horizontal density differences, such as sea breezes, thunderstorm outflows, powder snow avalanches, and turbidity currents, are frequently modeled as gravity currents. Efforts to develop simplified models of such currents date back to von Karman (1940), who considered a two-dimensional gravity current in an inviscid, irrotational and infinitely deep ambient. Benjamin (1968) presented an alternative model, focusing on the inviscid, irrotational flow past a gravity current in a finite-depth channel. More recently, Shin et al. (2004) proposed a model for gravity currents generated by partial-depth lock releases, considering a control volume that encompasses both fronts. All of the above models, in addition to the conservation of mass and horizontal momentum, invoke Bernoulli's law along some specific streamline in the flow field, in order to obtain a closed system of equations that can be solved for the front velocity as function of the current height. More recent computational investigations based on the Navier-Stokes equations, on the other hand, reproduce the dynamics of gravity currents based on the conservation of mass and momentum alone. We propose that it should therefore be possible to formulate a fundamental gravity current model without invoking Bernoulli's law. The talk will show that the front velocity of gravity currents can indeed be predicted as a function of their height from mass and momentum considerations alone, by considering the evolution of interfacial vorticity. This approach does not require information on the pressure field and therefore avoids the need for an energy closure argument such as those invoked by the earlier models. Predictions by the new theory are shown to be in close agreement with direct numerical simulation results. References Von Karman, T. 1940 The engineer grapples with nonlinear problems, Bull. Am. Math Soc. 46, 615-683. Benjamin, T.B. 1968 Gravity currents and related

  9. Development of a hydraulic model of the human systemic circulation

    NASA Technical Reports Server (NTRS)

    Sharp, M. K.; Dharmalingham, R. K.

    1999-01-01

    Physical and numeric models of the human circulation are constructed for a number of objectives, including studies and training in physiologic control, interpretation of clinical observations, and testing of prosthetic cardiovascular devices. For many of these purposes it is important to quantitatively validate the dynamic response of the models in terms of the input impedance (Z = oscillatory pressure/oscillatory flow). To address this need, the authors developed an improved physical model. Using a computer study, the authors first identified the configuration of lumped parameter elements in a model of the systemic circulation; the result was a good match with human aortic input impedance with a minimum number of elements. Design, construction, and testing of a hydraulic model analogous to the computer model followed. Numeric results showed that a three element model with two resistors and one compliance produced reasonable matching without undue complication. The subsequent analogous hydraulic model included adjustable resistors incorporating a sliding plate to vary the flow area through a porous material and an adjustable compliance consisting of a variable-volume air chamber. The response of the hydraulic model compared favorably with other circulation models.

  10. Asian Summer Monsoon Intraseasonal Variability in General Circulation Models

    SciTech Connect

    Sperber, K R; Annamalai, H

    2004-02-24

    The goals of this report are: (1) Analyze boreal summer Asian monsoon intraseasonal variability general circulation models--How well do the models represent the eastward and northward propagating components of the convection and how well do the models represent the interactive control that the western tropical Pacific rainfall exerts on the rainfall over India and vice-versa? (2) Role of air-sea interactions--prescribed vs. interactive ocean; and (3) Mean monsoon vs. variability.

  11. A general circulation model (GCM) parameterization of Pinatubo aerosols

    SciTech Connect

    Lacis, A.A.; Carlson, B.E.; Mishchenko, M.I.

    1996-04-01

    The June 1991 volcanic eruption of Mt. Pinatubo is the largest and best documented global climate forcing experiment in recorded history. The time development and geographical dispersion of the aerosol has been closely monitored and sampled. Based on preliminary estimates of the Pinatubo aerosol loading, general circulation model predictions of the impact on global climate have been made.

  12. Relations between winter precipitation and atmospheric circulation simulated by the Geophysical Fluid Dynamics Laboratory general circulation model

    USGS Publications Warehouse

    McCabe, G.J.; Dettinger, M.D.

    1995-01-01

    General circulation model (GCM) simulations of atmospheric circulation are more reliable than GCM simulations of temperature and precipitation. In this study, temporal correlations between 700 hPa height anomalies simulated winter precipitation at eight locations in the conterminous United States are compared with corresponding correlations in observations. The objectives are to 1) characterize the relations between atmospheric circulation and winter precipitation simulated by the GFDL, GCM for selected locations in the conterminous USA, ii) determine whether these relations are similar to those found in observations of the actual climate system, and iii) determine if GFDL-simulated precipitation is forced by the same circulation patterns as in the real atmosphere. -from Authors

  13. Modelling of the Circulation of the Western Indian Ocean

    DTIC Science & Technology

    1988-01-01

    MODELLING OF THE CIRCULATION OF THE WESTERN INDIAN OCEAN Contract N00014-85-K-0019 Julian P. McCreary Pijush K. Kundu Nova University Oceanographic...described below. (i) Cooling of the Arabian Sea: McCreary and Kundu (1989) have just completed a modeling study of the variability in the Arabian Sea...entirely responsible for the observed annual heat gained by the Arabian Sea. (ii) The Gulf of Tehuantepec: McCreary , Lee and Enfield (1989) have

  14. Recent advances in nanotechnology-based detection and separation of circulating tumor cells.

    PubMed

    Myung, Ja Hye; Tam, Kevin A; Park, Sin-jung; Cha, Ashley; Hong, Seungpyo

    2016-01-01

    Although circulating tumor cells (CTCs) in blood have been widely investigated as a potential biomarker for diagnosis and prognosis of metastatic cancer, their inherent rarity and heterogeneity bring tremendous challenges to develop a CTC detection method with clinically significant specificity and sensitivity. With advances in nanotechnology, a series of new methods that are highly promising have emerged to enable or enhance detection and separation of CTCs from blood. In this review, we systematically categorize nanomaterials, such as gold nanoparticles, magnetic nanoparticles, quantum dots, graphenes/graphene oxides, and dendrimers and stimuli-responsive polymers, used in the newly developed CTC detection methods. This will provide a comprehensive overview of recent advances in the CTC detection achieved through application of nanotechnology as well as the challenges that these existing technologies must overcome to be directly impactful on human health.

  15. Reproducibility of Digital PCR Assays for Circulating Tumor DNA Analysis in Advanced Breast Cancer

    PubMed Central

    Hrebien, Sarah; O’Leary, Ben; Beaney, Matthew; Schiavon, Gaia; Fribbens, Charlotte; Bhambra, Amarjit; Johnson, Richard; Turner, Nicholas

    2016-01-01

    Circulating tumor DNA (ctDNA) analysis has the potential to allow non-invasive analysis of tumor mutations in advanced cancer. In this study we assessed the reproducibility of digital PCR (dPCR) assays of circulating tumor DNA in a cohort of patients with advanced breast cancer and assessed delayed plasma processing using cell free DNA preservative tubes. We recruited a cohort of 96 paired samples from 71 women with advanced breast cancer who had paired blood samples processed either immediately or delayed in preservative tubes with processing 48–72 hours after collection. Plasma DNA was analysed with multiplex digital PCR (mdPCR) assays for hotspot mutations in PIK3CA, ESR1 and ERBB2, and for AKT1 E17K. There was 94.8% (91/96) agreement in mutation calling between immediate and delayed processed tubes, kappa 0.88 95% CI 0.77–0.98). Discordance in mutation calling resulted from low allele frequency and likely stochastic effects. In concordant samples there was high correlation in mutant copies per ml plasma (r2 = 0.98; p<0.0001). There was elevation of total cell free plasma DNA concentrations in 10.3% of delayed processed tubes, although overall quantification of total cell free plasma DNA had similar prognostic effects in immediate (HR 3.6) and delayed (HR 3.0) tubes. There was moderate agreement in changes in allele fraction between sequential samples in quantitative mutation tracking (r = 0.84, p = 0.0002). Delayed processing of samples using preservative tubes allows for centralized ctDNA digital PCR mutation screening in advanced breast cancer. The potential of preservative tubes in quantitative mutation tracking requires further research. PMID:27760227

  16. Low Circulating Levels of Dehydroepiandrosterone in Histologically Advanced Nonalcoholic Fatty Liver Disease

    PubMed Central

    Charlton, Michael; Angulo, Paul; Chalasani, Naga; Merriman, Ralph; Viker, Kimberly; Charatcharoenwitthaya, Phunchai; Sanderson, Schuyler; Gawrieh, Samer; Krishnan, Anuradha; Lindor, Keith

    2010-01-01

    The biological basis of variability in histological progression of nonalcoholic fatty liver disease (NAFLD) is unknown. Dehydroepiandrosterone(DHEA) is the most abundant steroid hormone and has been shown to influence sensitivity to oxidative stress, insulin sensitivity, and expression of peroxisome proliferator-activated receptor alpha and procollagen messenger RNA. Our aim was to determine whether more histologically advanced NAFLD is associated with low circulating levels of DHEA. Serum samples were obtained prospectively at the time of liver biopsy in 439 patients with NAFLD (78 in an initial and 361 in validation cohorts) and in controls with cholestatic liver disease (n = 44). NAFLD was characterized as mild [simple steatosis or nonalcoholic steatohepatitis (NASH) with fibrosis stage 0–2] or advanced (NASH with fibrosis stage 3–4). Serum levels of sulfated DHEA (DHEA-S) were measured by enzyme-linked immunosorbent assay. Patients with advanced NAFLD had lower plasma levels of DHEA-S than patients with mild NAFLD in both the initial (0.25 ± 0.07 versus 1.1 ± 0.09 µg/mL, P < 0.001) and validation cohorts (0.47 ± 0.06 versus 0.99 ± 0.04 µg/mL, P < 0.001). A “dose effect” of decreasing DHEA-S and incremental fibrosis stage was observed with a mean DHEA-S of 1.03 ± 0.05, 0.96 ± 0.07, 0.83 ± 0.11, 0.66 ± 0.11, and 0.35 ± 0.06 µg/mL for fibrosis stages 0, 1, 2, 3, and 4, respectively. All patients in both cohorts in the advanced NAFLD group had low DHEA-S levels, with the majority in the hypoadrenal range. The association between DHEA-S and severity of NAFLD persisted after adjusting for age. A relationship between disease/fibrosis severity and DHEA-S levels was not seen in patients with cholestatic liver diseases. Conclusion More advanced NAFLD, as indicated by the presence of NASH with advanced fibrosis stage, is strongly associated with low circulating DHEA-S. These data provide novel evidence for relative DHEA-S deficiency in patients with

  17. Advanced Turbulence Modeling Concepts

    NASA Technical Reports Server (NTRS)

    Shih, Tsan-Hsing

    2005-01-01

    The ZCET program developed at NASA Glenn Research Center is to study hydrogen/air injection concepts for aircraft gas turbine engines that meet conventional gas turbine performance levels and provide low levels of harmful NOx emissions. A CFD study for ZCET program has been successfully carried out. It uses the most recently enhanced National combustion code (NCC) to perform CFD simulations for two configurations of hydrogen fuel injectors (GRC- and Sandia-injector). The results can be used to assist experimental studies to provide quick mixing, low emission and high performance fuel injector designs. The work started with the configuration of the single-hole injector. The computational models were taken from the experimental designs. For example, the GRC single-hole injector consists of one air tube (0.78 inches long and 0.265 inches in diameter) and two hydrogen tubes (0.3 inches long and 0.0226 inches in diameter opposed at 180 degree). The hydrogen tubes are located 0.3 inches upstream from the exit of the air element (the inlet location for the combustor). To do the simulation, the single-hole injector is connected to a combustor model (8.16 inches long and 0.5 inches in diameter). The inlet conditions for air and hydrogen elements are defined according to actual experimental designs. Two crossing jets of hydrogen/air are simulated in detail in the injector. The cold flow, reacting flow, flame temperature, combustor pressure and possible flashback phenomena are studied. Two grid resolutions of the numerical model have been adopted. The first computational grid contains 0.52 million elements, the second one contains over 1.3 million elements. The CFD results have shown only about 5% difference between the two grid resolutions. Therefore, the CFD result obtained from the model of 1.3-million grid resolution can be considered as a grid independent numerical solution. Turbulence models built in NCC are consolidated and well tested. They can handle both coarse and

  18. Investigations of a circulation control airfoil flowfield using an advanced laser velocimeter

    NASA Technical Reports Server (NTRS)

    Novak, Charles J.; Cornelius, Kenneth C.

    1987-01-01

    The flowfield of a Circulation Control Airfoil was examined in detail through the use of a specially designed wind tunnel model and test program. Surface pressures on the model were obtained and the velocity field was surveyed in the trailing edge region of the model airfoil using the nonintrusive Laser Velocimetry technique. In this region mean flow and turbulence measurements indicate that, while the flowfield is similar to other wall-bounded jet flows, the external freestream plays an important role in the overall mixing and structure of the wall bounded flow. Finally, the turbulence measurements were used to compute eddy viscosities for the purpose of aiding computational fluid dynamics model development.

  19. ADCIRC: An Advanced Three-Dimensional Circulation Model for Shelves, Coasts, and Estuaries. Report 5. A Tropical Storm Database for the East and Gulf of Mexico Coasts of the United States.

    DTIC Science & Technology

    1994-08-01

    Westerink Department of Civil Engineering and Geological Sciences University of Notre Dame Notre Dame, IN 46556 Acceso .. R. A. Luettich, Jr. NTIS •-r Fo...tidal elevation and circulation applications to multiple tropical storm surge simulations. Therefore, although precise comparisons to existing data...storm surge elevations and depth-averaged velocity values is generated from the numerical simulation of multiple hum- canes. The ADCIRC-2DDI

  20. Treatment of cloud radiative effects in general circulation models

    SciTech Connect

    Wang, W.C.; Dudek, M.P.; Liang, X.Z.; Ding, M.

    1996-04-01

    We participate in the Atmospheric Radiation Measurement (ARM) program with two objectives: (1) to improve the general circulation model (GCM) cloud/radiation treatment with a focus on cloud verticle overlapping and layer cloud optical properties, and (2) to study the effects of cloud/radiation-climate interaction on GCM climate simulations. This report summarizes the project progress since the Fourth ARM Science Team meeting February 28-March 4, 1994, in Charleston, South Carolina.

  1. Baroclinic Rossby Wave Signature in a General Circulation Ocean Model.

    DTIC Science & Technology

    1983-06-01

    northwest with a wavelength cf 300 km. For other laritudes of the North acific Ocean , Price and Maqaard (1980) determined that first mode baroclinic Rossby...role in the latitude belt 40-50N in the North acific 10 -. - !o Ocean . Magaard (1983) ir. a paper discussing bariclin _c Rossty wave energetics...HD-AI132 219 BAROCLINIC ROSSBY WAVE SIGNATURE IN A GENERAL CIRCULATION OCEAN MODEL(U) NAVAL POSTGRADUATE SCHOOLU MONTEREY CA A H RUTSCH JUN 83

  2. Comparing a quasi-3D to a full 3D nearshore circulation model: SHORECIRC and ROMS

    USGS Publications Warehouse

    Haas, K.A.; Warner, J.C.

    2009-01-01

    Predictions of nearshore and surf zone processes are important for determining coastal circulation, impacts of storms, navigation, and recreational safety. Numerical modeling of these systems facilitates advancements in our understanding of coastal changes and can provide predictive capabilities for resource managers. There exists many nearshore coastal circulation models, however they are mostly limited or typically only applied as depth integrated models. SHORECIRC is an established surf zone circulation model that is quasi-3D to allow the effect of the variability in the vertical structure of the currents while maintaining the computational advantage of a 2DH model. Here we compare SHORECIRC to ROMS, a fully 3D ocean circulation model which now includes a three dimensional formulation for the wave-driven flows. We compare the models with three different test applications for: (i) spectral waves approaching a plane beach with an oblique angle of incidence; (ii) monochromatic waves driving longshore currents in a laboratory basin; and (iii) monochromatic waves on a barred beach with rip channels in a laboratory basin. Results identify that the models are very similar for the depth integrated flows and qualitatively consistent for the vertically varying components. The differences are primarily the result of the vertically varying radiation stress utilized by ROMS and the utilization of long wave theory for the radiation stress formulation in vertical varying momentum balance by SHORECIRC. The quasi-3D model is faster, however the applicability of the fully 3D model allows it to extend over a broader range of processes, temporal, and spatial scales. ?? 2008 Elsevier Ltd.

  3. Circulating advanced glycation peptides in streptozotocin-induced diabetic rats: evidence for preferential modification of IgG light chains.

    PubMed

    Gugliucci, A; Menini, T

    1998-01-01

    As the glycation/glycoxidation hypothesis for the genesis of diabetic complications is achieving widespread acceptance, much attention is being paid to the role of low molecular weight advanced glycation (AGE) adducts, as second generation glycating agents. We set out a study with the objective of attesting the presence of increased amounts of AGE-peptides in the circulation of streptozotocin-induced diabetic rats and to determine the nature of the plasma proteins which are main targets for advanced glycation. AGE (Ex 370/Em 440 nm) and pentosidine fluorescence (Ex 335/Em 385 nm) were significantly higher in plasma from diabetic rats after only one month of hyperglycemia as compared to controls (35 +/- 7 vs 25 +/- 2 AU, p< 0.05 and 54 +/- 14 vs 27 +/- 3 AU, p< 0.01 respectively). AGE-peptides (<10 kDa) were more than two-fold higher in diabetic animals. Immunoblots after SDS-PAGE of plasma proteins showed that AGE-IgG displayed a selective predominant increment in the same animals. When native rat IgG was incubated in the presence of AGE-peptides isolated from diabetic animals, AGE modification was already apparent after only 24 h of incubation, and was particularly important for light chains. AGE-immunoreactive light chains displayed an apparent increase in molecular weight. Aminoguanidine prevented, while copper enhanced AGE binding to IgG light chains. Our data validate the streptozotocin-induced diabetic rat as a model reproducing the presence of circulating AGE-peptides, give evidence that IgG are preferential targets for advanced glycation in plasma and suggest that this modification, mediated by AGE-peptides, can be prevented by aminoguanidine.

  4. ADVANCED MIXING MODELS

    SciTech Connect

    Lee, S; Dimenna, R; Tamburello, D

    2011-02-14

    height from zero to 10 ft. The sludge has been characterized and modeled as micron-sized solids, typically 1 to 5 microns, at weight fractions as high as 20 to 30 wt%, specific gravities to 1.4, and viscosities up to 64 cp during motion. The sludge is suspended and mixed through the use of submersible slurry jet pumps. To suspend settled sludge, water is added to the tank as a slurry medium and stirred with the jet pump. Although there is considerable technical literature on mixing and solid suspension in agitated tanks, very little literature has been published on jet mixing in a large-scale tank. One of the main objectives in the waste processing is to provide feed of a uniform slurry composition at a certain weight percentage (e.g. typically {approx}13 wt% at SRS) over an extended period of time. In preparation of the sludge for slurrying, several important questions have been raised with regard to sludge suspension and mixing of the solid suspension in the bulk of the tank: (1) How much time is required to prepare a slurry with a uniform solid composition? (2) How long will it take to suspend and mix the sludge for uniform composition in any particular waste tank? (3) What are good mixing indicators to answer the questions concerning sludge mixing stated above in a general fashion applicable to any waste tank/slurry pump geometry and fluid/sludge combination?

  5. The evaluation of retinal circulation in advanced diabetic retinopathy before and after panretinal laser photocoagulation by scanning laser opthalmoscope

    NASA Astrophysics Data System (ADS)

    Okano, Tadashi

    2005-07-01

    I investigated the effects of panretinal laser photocoagulation (PRP) on the velocity of retinal circulation in diabetic retinopathy. The retinal circulation was evaluated by means of rapid serial fluorescein angiography (FAG), employing scanning laser ophthalmoscope. FAG was conducted at the rate of 30 frames per seconds in video-tape. Disc-to-macula transit time (DMTT) was defined as the parameter to evaluate the retinal circulation. Diabetic 28 eyes with advanced diabetic retinopathy were examined to measure the DMTT before and after PRP. Normal 30 eyes used as control. Mean DMTT decreased from 9.8+/-1.5 seconds before PRP to 8.2+/-1.5 seconds after PRP in 28 diabetic eyes. The value with improvement after PRP was significantly shorter than the value before PRP ( p < 0.05 ). These values before and after PRP were significantly longer than that (3.7+/-0.7 seconds ) in normal 30 eyes ( p < 0.01 ). Retinal circulation is retarded in diabetic retinopathy. The retardation of retinal circulation in diabetic retinopathy improves after PRP, but the value after PRP can not recover until the control level. This study was performed to reveal therapeutic effect to panretinal laser photocoagulation (PRP) for the retardation of retinal circulation in diabetic retinopathy. I investigated the effects of PRP on the velocity of retinal circulation in patients with advanced diabetic retinopathy.

  6. A parallel coupled oceanic-atmospheric general circulation model

    SciTech Connect

    Wehner, M.F.; Bourgeois, A.J.; Eltgroth, P.G.; Duffy, P.B.; Dannevik, W.P.

    1994-12-01

    The Climate Systems Modeling group at LLNL has developed a portable coupled oceanic-atmospheric general circulation model suitable for use on a variety of massively parallel (MPP) computers of the multiple instruction, multiple data (MIMD) class. The model is composed of parallel versions of the UCLA atmospheric general circulation model, the GFDL modular ocean model (MOM) and a dynamic sea ice model based on the Hiber formulation extracted from the OPYC ocean model. The strategy to achieve parallelism is twofold. One level of parallelism is accomplished by applying two dimensional domain decomposition techniques to each of the three constituent submodels. A second level of parallelism is attained by a concurrent execution of AGCM and OGCM/sea ice components on separate sets of processors. For this functional decomposition scheme, a flux coupling module has been written to calculate the heat, moisture and momentum fluxes independent of either the AGCM or the OGCM modules. The flux coupler`s other roles are to facilitate the transfer of data between subsystem components and processors via message passing techniques and to interpolate and aggregate between the possibly incommensurate meshes.

  7. Circulating tumor cells: advances in isolation and analysis, and challenges for clinical applications

    PubMed Central

    Harouaka, Ramdane; Kang, Zhigang; Zheng, Siyang; Cao, Liang

    2013-01-01

    Circulating tumor cells (CTCs) are rare cancer cells released from tumors into the bloodstream that are thought to have a key role in cancer metastasis. The presence of CTCs has been associated with worse prognosis in several major cancer types, including breast, prostate and colorectal cancer. There is considerable interest in CTC research and technologies for their potential use as cancer biomarkers that may enhance cancer diagnosis and prognosis, facilitate drug development, and improve the treatment of cancer patients. This review provides an update on recent progress in CTC isolation and molecular characterization technologies. Furthermore, the review covers significant advances and limitations in the clinical applications of CTC-based assays for cancer prognosis, response to anti-cancer therapies, and exploratory studies in biomarkers predictive of sensitivity and resistance to cancer therapies. PMID:24134902

  8. Modelling wildfire activity in Iberia with different Atmospheric Circulation WTs

    NASA Astrophysics Data System (ADS)

    Sousa, P. M.; Trigo, R.; Pereira, M. G.; Rasilla, D.; Gouveia, C.

    2012-04-01

    This work focuses on the spatial and temporal variability of burnt area (BA) for the entire Iberian Peninsula (IP) and on the construction of statistical models to reproduce the inter-annual variability, based on Weather Types Classification (WTC). A common BA dataset was assembled for the first time for the entire Iberian Peninsula, by merging BA records for the 66 administrative regions of Portugal and Spain. A normalization procedure was then applied to the various size regions before performing a k-means cluster analysis to identify large areas characterized by similar fire regimes. The most compelling results were obtained for 4 clusters (Northwestern, Northern, Southwestern and Eastern) whose spatial patterns and seasonal fire regimes are shown to be related with constraining factors such as topography, vegetation cover and climate conditions. The response of fire burnt surface at monthly time scales to both long-term climatic pre-conditions and short-term synoptic forcing was assessed through correlation and regression analysis using: (i) temperature and precipitation from 2 to 7 months in advance to fire peak season; (ii) synoptic weather patterns derived from 11 distinct classifications derived under the COSTaction-733. Different responses were obtained for each of the considered regions: (i) a relevant link between BA and short-term synoptic forcing (represented by monthly frequencies of WTC) was identified for all clusters; (ii) long-term climatic preconditioning was relevant for all but one cluster (Northern). Taking into account these links, we developed stepwise regression models with the aim of reproducing the observed BA series (i.e. in hindcast mode). These models were based on the best climatic and synoptic circulation predictors identified previously. All models were cross-validated and their performance varies between clusters, though models exclusively based on WTCs tend to better reproduce annual BA time series than those only based on pre

  9. Interactive data exploration and particle tracking for general circulation models

    NASA Technical Reports Server (NTRS)

    Rosenbaum, R. I.; Peskin, R. L.; Walther, S. S.; Zinn, H. P.

    1995-01-01

    The SCENE environment for interactive visualization of complex data sets is discussed. This environment is used to create tools for graphical exploration of atmospheric flow models. These tools may be extended by the user in a seamless manner, so that no programming is required. A module for accurately tracing field lines and particle trajectories in SCENE is presented. This is used to examine the flowfield qualitatively with streamlines and pathlines and to identify critical points in the velocity field. The paper also describes a visualization tool for general circulation models on which the primary features of the environment are demonstrated.

  10. Tropical disturbances in relation to general circulation modeling

    NASA Technical Reports Server (NTRS)

    Estoque, M. A.

    1982-01-01

    The initial results of an evaluation of the performance of the Goddard Laboratory of Atmospheric Simulation general circulation model depicting the tropical atmosphere during the summer are presented. Because the results show the existence of tropical wave disturbances throughout the tropics, the characteristics of synoptic disturbances over Africa were studied and a synoptic case study of a selected disturbance in this area was conducted. It is shown that the model is able to reproduce wave type synoptic disturbances in the tropics. The findings show that, in one of the summers simulated, the disturbances are predominantly closed vortices; in another summer, the predominant disturbances are open waves.

  11. A Moist Idealized Test Case for Atmospheric General Circulation Models

    NASA Astrophysics Data System (ADS)

    Thatcher, D.; Jablonowski, C.; Zarzycki, C.

    2013-12-01

    The vast array of dynamical and physical processes within atmospheric general circulation models (GCMs) makes it difficult to correctly distinguish the sources of error within a model. Therefore, simplified test cases are important in testing the accuracy of individual model components, such as the fluid flow component in the dynamical core. Typically, dynamical cores are coupled to complex subgrid-scale physical parameterization packages, and the nonlinear interactions mask the causes and effects of atmospheric phenomena. Idealized tests are a computationally efficient method for analyzing the underlying numerical techniques of dynamical cores. The newly proposed test case is based on the widely-used Held and Suarez (1994) (HS) test for dry dynamical cores. The latter replaces the full physical parameterization package with a Newtonian temperature relaxation and Rayleigh damping of low-level winds on a flat planet. However, the impact of moisture, a crucial physics-dynamics coupling process, is missing from the HS test. Here we present a moist variant of the HS test case to create a test case of intermediate complexity with idealized moisture feedbacks. It uses simplified physical processes to model large-scale condensation, boundary layer turbulence, and surface fluxes of horizontal momentum, latent heat, and sensible heat between the atmosphere and an ocean-covered planet (Reed and Jablonowski, 2012). We apply this test to four dynamical cores within NCAR's Community Atmosphere Model version 5.3, including the Finite Volume, Eulerian spectral transform, semi-Lagrangian spectral transform, and Spectral Element dynamical cores. We analyze the kinetic energy spectra, general circulation, and precipitation of this new moist idealized test case across all four dynamical cores. Simulations of the moist idealized test case are compared to aqua-planet experiments with complex physical parameterizations. The moist idealized test case successfully reproduces many features

  12. Relaxation oscillations in an idealized ocean circulation model

    NASA Astrophysics Data System (ADS)

    Roberts, Andrew; Saha, Raj

    2016-06-01

    This work is motivated by a desire to understand transitions between stable equilibria observed in Stommel's 1961 thermohaline circulation model. We adapt the model, including a forcing parameter as a dynamic slow variable. The resulting model is a piecewise-smooth, three time-scale system. The model is analyzed using geometric singular perturbation theory to demonstrate the existence of attracting periodic orbits. The system is capable of producing classical relaxation oscillations as expected, but there is also a parameter regime in which the model exhibits small amplitude oscillations known as canard cycles. Forcing the model with obliquity variations from the last 100,000 years produces oscillations that are modulated in amplitude and frequency. The output shows similarities with important features of the climate proxy data of the same period.

  13. Numerical study of three-dimensional shelf circulation on the Scotian Shelf using a shelf circulation model

    NASA Astrophysics Data System (ADS)

    Ohashi, Kyoko; Sheng, Jinyu; Thompson, Keith R.; Hannah, Charles G.; Ritchie, Harold

    2009-09-01

    A numerical shelf circulation model was developed for the Scotian Shelf, using a nested-grid setup consisting of a three-dimensional baroclinic inner model embedded inside a two-dimensional barotropic outer model. The shelf circulation model is based on the Princeton Ocean Model and driven by three-hourly atmospheric forcing provided by a numerical weather forecast model and by tidal forcing specified at the inner model's open boundaries based on pre-calculated tidal harmonic constants. The outer model simulates the depth-mean circulation forced by wind and atmospheric pressure fields over the northwest Atlantic Ocean with a horizontal resolution of 1/12°. The inner model simulates the three-dimensional circulation over the Gulf of St. Lawrence, the Scotian Shelf, and the adjacent slope with a horizontal resolution of 1/16°. The performance of the shelf circulation model is assessed by comparing model results with oceanographic observations made along the Atlantic coast of Nova Scotia and in the vicinity of Sable Island (on the Scotian Shelf) during two periods: October 2000-March 2001 and April-June 2002. Analysis of model results on Sable Island Bank indicates that tidal currents account for as much as ˜80% of the total variance of near-bottom currents, and currents driven by local winds account for ˜30% of the variance of the non-tidal near-bottom currents. Shelf waves generated remotely by winds and propagating into the region also play an important role in the near-bottom circulation on the bank.

  14. Integrated and spectral energetics of the GLAS general circulation model

    NASA Technical Reports Server (NTRS)

    Tenenbaum, J.

    1982-01-01

    Integrated and spectral error energetics of the GLAS General circulation model are compared with observations for periods in January 1975, 1976, and 1977. For two cases the model shows significant skill in predicting integrated energetics quantities out to two weeks, and for all three cases, the integrated monthly mean energetics show qualitative improvements over previous versions of the model in eddy kinetic energy and barotropic conversions. Fundamental difficulties remain with leakage of energy to the stratospheric level, particularly above strong initial jet streams associated in part with regions of steep terrain. The spectral error growth study represents the first comparison of general circulation model spectral energetics predictions with the corresponding observational spectra on a day by day basis. The major conclusion is that eddy kinetics energy can be correct while significant errors occur in the kinetic energy of wavenumber 3. Both the model and observations show evidence of single wavenumber dominance in eddy kinetic energy and the correlation of spectral kinetics and potential energy.

  15. Numerical Model Studies of the Martian Mesoscale Circulations

    NASA Technical Reports Server (NTRS)

    Segal, Moti; Arritt, Raymond W.

    1997-01-01

    The study objectives were to evaluate by numerical modeling various possible mesoscale circulation on Mars and related atmospheric boundary layer processes. The study was in collaboration with J. Tillman of the University of Washington (who supported the study observationally). Interaction has been made with J. Prusa of Iowa State University in numerical modeling investigation of dynamical effects of topographically-influenced flow. Modeling simulations included evaluations of surface physical characteristics on: (i) the Martian atmospheric boundary layer and (ii) their impact on thermally and dynamically forced mesoscale flows. Special model evaluations were made in support of selection of the Pathfinder landing sites. J. Tillman's finding of VL-2 inter-annual temperature difference was followed by model simulations attempting to point out the forcing for this feature. Publication of the results in the reviewed literature in pending upon completion of the manuscripts in preparation as indicated later.

  16. Modeling of a coal-fired natural circulation boiler

    SciTech Connect

    Bhambare, K.S.; Mitra, S.K.; Gaitonde, U.N.

    2007-06-15

    Modeling of a natural circulation boiler for a coal-fired thermal power station is presented here. The boiler system is divided into seven subcomponents, and for each section, models based on conservation of mass, momentum, and energy are formulated. The pressure drop at various sections and the heat transfer coefficients are computed using empirical correlations. Solutions are obtained by using SIMULINK. The model is validated by comparing its steady state and dynamic responses with the actual plant data. Open loop responses of the model to the step changes in the operating parameters, such as pressure, temperature, steam flow, feed water flow, are also analyzed. The present model can be used for the development and design of effective boiler control systems.

  17. Early Eocene's climate and ocean circulation from coupled model simulations

    NASA Astrophysics Data System (ADS)

    Weber, Tobias; Thomas, Maik

    2014-05-01

    While proxy data provide a snapshot of climate conditions at a specific location, coupled atmosphere-ocean models are able to expand this knowledge over the globe. Therefore, they are indispensable tools for understanding past climate conditions. We model the dynamical state of atmosphere and ocean during the Early Eocene and pre-industrial times, using the coupled atmosphere-ocean model ECHAM5/MPIOM with realistic reconstructions of vegetation and CO2. The resulting simulated climate variables are compared to terrestrial and oceanic proxies. The Early Eocene climate is in the global mean warmer (~13°C) and wetter (~1 mm/d) than in pre-industrial times. Especially temperatures in the Southern Ocean, the Greenland Sea and Arctic Ocean raise by up to 25K, being in accordance with surface temperature estimates from terrestrial and marine proxy data. The oceans are hereby rendered ice-free, leading to a decrease of polar albedo and thereby facilitating polar warming. This leads to a by 5K diminished equator-to-pole temperature gradient. Warmer temperatures as well as changed bathymetry have an effect on ocean dynamics in the Early Eocene. Although deep-water formation can be found in the Greenland Sea, Weddell Sea, and Tethys Sea, it is weaker than in the pre-industrial run and the resulting circulation is shallower. This is not only visible in water transport through sea gates but also in the Atlantic Meridional Overturning Circulation (AMOC), adopting its maximum at 700m depths in the Early Eocene, while maximum transport is reached in the pre-industrial control run at 1200m. Albeit a shallow and weak thermohaline circulation, a global ocean conveyor belt is being triggered, causing a transport from the areas of subduction through the Atlantic and Southern Oceans into the Indian and Pacific Oceans.

  18. Using a Gravity Model to Predict Circulation in a Public Library System.

    ERIC Educational Resources Information Center

    Ottensmann, John R.

    1995-01-01

    Describes the development of a gravity model based upon principles of spatial interaction to predict the circulation of libraries in the Indianapolis-Marion County Public Library (Indiana). The model effectively predicted past circulation figures and was tested by predicting future library circulation, particularly for a new branch library.…

  19. (CO sub 2 uptake in an Ocean Circulation Model)

    SciTech Connect

    Siegenthaler, U.C.

    1990-11-06

    The traveler collaborated with Drs. J. L. Sarmiento and J. C. Orr of the Program in Atmospheric Sciences at Princeton University to finish the article A Perturbation Simulation of CO{sub 2} Uptake in an Ocean Circulation Model,'' which has been submitted to the Journal of Geophysical Research for publication. With F. Joos, a graduate student from the University of Bern, the traveler started writing a journal article describing a box model of the global carbon cycle that is an extension of the one-dimensional box-diffusion model. The traveler further collaborated with F. Joos and Dr. J. L. Sarmiento on modeling the potential enhancement of oceanic CO{sub 2} uptake by fertilizing the southern ocean with iron. A letter describing the results is currently being written for the journal Nature.

  20. Anisotropic Mesoscale Eddy Transport in Ocean General Circulation Models

    NASA Astrophysics Data System (ADS)

    Reckinger, S. J.; Fox-Kemper, B.; Bachman, S.; Bryan, F.; Dennis, J.; Danabasoglu, G.

    2014-12-01

    Modern climate models are limited to coarse-resolution representations of large-scale ocean circulation that rely on parameterizations for mesoscale eddies. The effects of eddies are typically introduced by relating subgrid eddy fluxes to the resolved gradients of buoyancy or other tracers, where the proportionality is, in general, governed by an eddy transport tensor. The symmetric part of the tensor, which represents the diffusive effects of mesoscale eddies, is universally treated isotropically in general circulation models. Thus, only a single parameter, namely the eddy diffusivity, is used at each spatial and temporal location to impart the influence of mesoscale eddies on the resolved flow. However, the diffusive processes that the parameterization approximates, such as shear dispersion, potential vorticity barriers, oceanic turbulence, and instabilities, typically have strongly anisotropic characteristics. Generalizing the eddy diffusivity tensor for anisotropy extends the number of parameters to three: a major diffusivity, a minor diffusivity, and the principal axis of alignment. The Community Earth System Model (CESM) with the anisotropic eddy parameterization is used to test various choices for the newly introduced parameters, which are motivated by observations and the eddy transport tensor diagnosed from high resolution simulations. Simply setting the ratio of major to minor diffusivities to a value of five globally, while aligning the major axis along the flow direction, improves biogeochemical tracer ventilation and reduces global temperature and salinity biases. These effects can be improved even further by parameterizing the anisotropic transport mechanisms in the ocean.

  1. A Pacific Ocean general circulation model for satellite data assimilation

    NASA Technical Reports Server (NTRS)

    Chao, Y.; Halpern, D.; Mechoso, C. R.

    1991-01-01

    A tropical Pacific Ocean General Circulation Model (OGCM) to be used in satellite data assimilation studies is described. The transfer of the OGCM from a CYBER-205 at NOAA's Geophysical Fluid Dynamics Laboratory to a CRAY-2 at NASA's Ames Research Center is documented. Two 3-year model integrations from identical initial conditions but performed on those two computers are compared. The model simulations are very similar to each other, as expected, but the simulations performed with the higher-precision CRAY-2 is smoother than that with the lower-precision CYBER-205. The CYBER-205 and CRAY-2 use 32 and 64-bit mantissa arithmetic, respectively. The major features of the oceanic circulation in the tropical Pacific, namely the North Equatorial Current, the North Equatorial Countercurrent, the South Equatorial Current, and the Equatorial Undercurrent, are realistically produced and their seasonal cycles are described. The OGCM provides a powerful tool for study of tropical oceans and for the assimilation of satellite altimetry data.

  2. Modeling waves and circulation in Lake Pontchartrain, Louisiana

    USGS Publications Warehouse

    Signell, Richard P.; List, Jeffrey H.

    1997-01-01

    The U.S. Geological Survey is conducting a study of storm-driven sediment resuspension and transport in Lake Pontchartrain, Louisiana. Two critical processes related to sediment transport in the lake are (1) the resuspension of sediments due to wind-generated storm waves and (2) the movement of resuspended material by lake currents during storm wind events. The potential for sediment resuspension is being studied with the wave prediction model which simulates local generation of waves by wind and shallow-water effects on waves (refraction, shoaling, bottom friction, and breaking). Long-term wind measurements are then used to determine the regional "climate" of bottom orbital velocity (showing the spatial and temporal variability of wave-induced currents at the bottom). The circulation of the lake is being studied with a three-dimensional hydrodynamic model. Results of the modeling effort indicate that remote forcing due to water levels in Mississippi Sound dominate the circulation near the passes in the eastern end of the lake, while local wind forcing dominates water movement in the western end. During typical storms with winds from the north-northeast or the south-southeast, currents along the south coast near New Orleans generally transport material westward, while material in the central region moves against the wind. When periods of sustained winds are followed by a drop in coastal sea level, a large amount of suspended sediment can be flushed from the lake.

  3. Circulation Control Model Experimental Database for CFD Validation

    NASA Technical Reports Server (NTRS)

    Paschal, Keith B.; Neuhart, Danny H.; Beeler, George B.; Allan, Brian G.

    2012-01-01

    A 2D circulation control wing was tested in the Basic Aerodynamic Research Tunnel at the NASA Langley Research Center. A traditional circulation control wing employs tangential blowing along the span over a trailing-edge Coanda surface for the purpose of lift augmentation. This model has been tested extensively at the Georgia Tech Research Institute for the purpose of performance documentation at various blowing rates. The current study seeks to expand on the previous work by documenting additional flow-field data needed for validation of computational fluid dynamics. Two jet momentum coefficients were tested during this entry: 0.047 and 0.114. Boundary-layer transition was investigated and turbulent boundary layers were established on both the upper and lower surfaces of the model. Chordwise and spanwise pressure measurements were made, and tunnel sidewall pressure footprints were documented. Laser Doppler Velocimetry measurements were made on both the upper and lower surface of the model at two chordwise locations (x/c = 0.8 and 0.9) to document the state of the boundary layers near the spanwise blowing slot.

  4. Circulating fluidized bed tehnology in biomass combustion-performance, advances and experiences

    SciTech Connect

    Mutanen, K.I.

    1995-11-01

    Development of fluidized bed combustion (FBC) was started both in North America and in Europe in the 1960`s. In Europe and especially in Scandinavia the major driving force behind the development was the need to find new more efficient technologies for utilization of low-grade fuels like different biomasses and wastes. Both bubbling fluidized bed (BFB) and circulating fluidized bed (CFB) technologies were under intensive R&D,D efforts and have now advanced to dominating role in industrial and district heating power plant markets in Europe. New advanced CFB designs are now entering the markets. In North America and especially in the US the driving force behind the FBC development was initially the need to utilize different types of coals in a more efficient and environmentally acceptable way. The present and future markets seem to be mainly in biomass and multifuel applications where there is benefit from high combustion efficiency, high fuel flexibility and low emissions such as in the pulp and paper industry. The choice between CFB technology and BFB technology is based on selected fuels, emission requirements, plant size and on technical and economic feasibility. Based on Scandinavian experience there is vast potential in the North American industry to retrofit existing oil fired, pulverized coal fired, chemical recovery or grate fired boilers with FBC systems or to build a new FBC based boiler plant. This paper will present the status of CFB technologies and will compare technical and economic feasibility of CFB technology to CFB technology to BFB and also to other combustion methods. Power plant projects that are using advanced CFB technology e.g. Ahlstrom Pyroflow Compact technology for biomass firing and co-firing of biomass with other fuels will also be introduced.

  5. Advanced glycation end products, carotid atherosclerosis, and circulating endothelial progenitor cells in patients with end-stage renal disease.

    PubMed

    Ueno, Hiroki; Koyama, Hidenori; Fukumoto, Shinya; Tanaka, Shinji; Shoji, Takuhito; Shoji, Tetsuo; Emoto, Masanori; Tahara, Hideki; Inaba, Masaaki; Kakiya, Ryusuke; Tabata, Tsutomu; Miyata, Toshio; Nishizawa, Yoshiki

    2011-04-01

    Numbers of endothelial progenitor cells (EPCs) have been shown to be decreased in subjects with end-stage renal disease (ESRD), the mechanism of which remained poorly understood. In this study, mutual association among circulating EPC levels, carotid atherosclerosis, serum pentosidine, and skin autofluorescence, a recently established noninvasive measure of advanced glycation end products accumulation, was examined in 212 ESRD subjects undergoing hemodialysis. Numbers of circulating EPCs were measured as CD34+ CD133+ CD45(low) VEGFR2+ cells and progenitor cells as CD34+ CD133+ CD45(low) fraction by flow cytometry. Skin autofluorescence was assessed by the autofluorescence reader; and serum pentosidine, by enzyme-linked immunosorbent assay. Carotid atherosclerosis was determined as intimal-medial thickness (IMT) measured by ultrasound. Circulating EPCs were significantly and inversely correlated with skin autofluorescence in ESRD subjects (R = -0.216, P = .002), but not with serum pentosidine (R = -0.079, P = .25). Circulating EPCs tended to be inversely associated with IMT (R = -0.125, P = .069). Intimal-medial thickness was also tended to be correlated positively with skin autofluorescence (R = 0.133, P = .054) and significantly with serum pentosidine (R = 0.159, P = .019). Stepwise multiple regression analyses reveal that skin autofluorescence, but not serum pentosidine and IMT, was independently associated with low circulating EPCs. Of note, skin autofluorescence was also inversely and independently associated with circulating progenitor cells. Thus, tissue accumulated, but not circulating, advanced glycation end products may be a determinant of a decrease in circulating EPCs in ESRD subjects.

  6. Circulation and rainfall climatology of a 10-year (1979 - 1988) integration with the Goddard Laboratory for atmospheres general circulation model

    NASA Technical Reports Server (NTRS)

    Kim, J.-H.; Sud, Y. C.

    1993-01-01

    A 10-year (1979-1988) integration of Goddard Laboratory for Atmospheres (GLA) general circulation model (GCM) under Atmospheric Model Intercomparison Project (AMIP) is analyzed and compared with observation. The first momentum fields of circulation variables and also hydrological variables including precipitation, evaporation, and soil moisture are presented. Our goals are (1) to produce a benchmark documentation of the GLA GCM for future model improvements; (2) to examine systematic errors between the simulated and the observed circulation, precipitation, and hydrologic cycle; (3) to examine the interannual variability of the simulated atmosphere and compare it with observation; and (4) to examine the ability of the model to capture the major climate anomalies in response to events such as El Nino and La Nina. The 10-year mean seasonal and annual simulated circulation is quite reasonable compared to the analyzed circulation, except the polar regions and area of high orography. Precipitation over tropics are quite well simulated, and the signal of El Nino/La Nina episodes can be easily identified. The time series of evaporation and soil moisture in the 12 biomes of the biosphere also show reasonable patterns compared to the estimated evaporation and soil moisture.

  7. Strong coupling among Antarctic ice shelves, ocean circulation and sea ice in a global sea-ice - ocean circulation model

    NASA Astrophysics Data System (ADS)

    Sergienko, Olga

    2016-04-01

    The thermodynamic effects of Antarctic ice shelf interaction with ocean circulation are investigated using a global, high-resolution, isopycnal ocean-circulation model coupled to a sea-ice model. The model uses NASA MERRA Reanalysis from 1992 to 2011 as atmospheric forcing. The simulated long-period variability of ice-shelf melting/freezing rates differ across geographic locations. The ice shelves in Antarctic Peninsula, Amundsen and Bellingshausen sea embayments and the Amery Ice Shelf experience an increase in melting starting from 2005. This increase in melting is due to an increase in the subsurface (100-500 m) ocean heat content in the embayments of these ice shelves, which is caused by an increase in sea-ice concentration after 2005, and consequent reduction of the heat loss to the atmosphere. Our simulations provide a strong evidence for a coupling between ocean circulation, sea ice and ice shelves.

  8. A Coupled General Circulation Model of the Archean Earth

    NASA Astrophysics Data System (ADS)

    Wolf, E. T.; Toon, O. B.

    2011-12-01

    We present results from a new coupled general circulation model suitable for deep paleoclimate studies. Particular interest is given to the faint young Sun paradox. The model is based on the Community Earth System Model maintained by the National Center for Atmospheric Research [1]. Prognostic atmosphere, ocean, land, ice, and hydrological cycle models are coupled. A new correlated-k radiative transfer model has been implemented allowing accurate flux calculations for anoxic atmospheres containing high concentrations of CO2 and CH4 [2, 3]. This model represents a significant improvement upon one-dimensional radiative-convective climate models used previously to study ancient climate [4]. Cloud and ice albedo feedbacks will be accurately quantified and new constraints on Archean surface temperatures will be revealed. References [1] Collins W.D. et al. "Description of the NCAR Community Atmosphere Model (CAM 3.0)." NCAR Technical Note, 2004. [2] Toon O.B., McKay, C.P., Ackerman, T.P. "Rapid Calculation of Radiative Heating Rates and Photodissociation Rates in Inhomogeneous Multiple Scattering Atmospheres." J. Geo. Res., 94(D13), 16287 - 16301, 1989. [3] Mlawer, E.J., et al. "Radiative transfer for inhomogeneous atmospheres: RRTM, a validated correlated-k model for the longwave." J. Geo. Res., 102(D14), 16663 - 16682, 1997. [4] Kasting J.F., Pollack, J.B., Crisp, D. "Effects of High CO2 Levels on Surface Temperature and Atmospheric Oxidation State of the Early Earth." J. Atm. Chem., 1, 403-428, 1984.

  9. Recent advances in atomic modeling

    SciTech Connect

    Goldstein, W.H.

    1988-10-12

    Precision spectroscopy of solar plasmas has historically been the goad for advances in calculating the atomic physics and dynamics of highly ionized atoms. Recent efforts to understand the laboratory plasmas associated with magnetic and inertial confinement fusion, and with X-ray laser research, have played a similar role. Developments spurred by laboratory plasma research are applicable to the modeling of high-resolution spectra from both solar and cosmic X-ray sources, such as the photoionized plasmas associated with accretion disks. Three of these developments in large scale atomic modeling are reviewed: a new method for calculating large arrays of collisional excitation rates, a sum rule based method for extending collisional-radiative models and modeling the effects of autoionizing resonances, and a detailed level accounting calculation of resonant excitation rates in FeXVII. 21 refs., 5 figs., 2 tabs.

  10. Different approaches to model the nearshore circulation in the south shore of O'ahu, Hawaii

    NASA Astrophysics Data System (ADS)

    Marcos Azevedo Correia de Souza, Joao; Powell, Brian

    2017-01-01

    The dynamical interaction between currents, bathymetry, waves, and estuarine outflow has significant impacts on the surf zone. We investigate the impacts of two strategies to include the effect of surface gravity waves on an ocean circulation model of the south shore of O'ahu, Hawaii. This area provides an ideal laboratory for the development of nearshore circulation modeling systems for reef-protected coastlines. We use two numerical models for circulation and waves: Regional Ocean Modeling System (ROMS) and Simulating Waves Nearshore (SWAN) model, respectively. The circulation model is nested within larger-scale models that capture the tidal, regional, and wind-forced circulation of the Hawaiian archipelago. Two strategies are explored for circulation modeling: forcing by the output of the wave model and online, two-way coupling of the circulation and wave models. In addition, the circulation model alone provides the reference for the circulation without the effect of the waves. These strategies are applied to two experiments: (1) typical trade-wind conditions that are frequent during summer months, and (2) the arrival of a large winter swell that wraps around the island. The results show the importance of considering the effect of the waves on the circulation and, particularly, the circulation-wave coupled processes. Both approaches show a similar nearshore circulation pattern, with the presence of an offshore current in the middle beaches of Waikiki. Although the pattern of the offshore circulation remains the same, the coupled waves and circulation produce larger significant wave heights ( ≈ 10 %) and the formation of strong alongshore and cross-shore currents ( ≈ 1 m s-1).

  11. Net diffusivity in ocean general circulation models with nonuniform grids

    NASA Technical Reports Server (NTRS)

    Yin, F. L.; Fung, I. Y.

    1991-01-01

    The numerical vertical diffusivity K(num), embedded in a numerical ocean general circulation model with nonuniform vertical grid, is estimated. It is shown that in a downwelling region, K(num) is negative for a grid with grid size increasing with depth. When the grid size increment, or the downward vertical velocity, is large, K(num) may exceed the vertical diffusivity specified and may result in a negative effective vertical diffusivity. Therefore care needs to be taken to specify the vertical diffusivity in a numerical model with nonuniform grid, and a lower bound is generally imposed in order to avoid an unphysical negative value. Some possible effects of the negative effective diffusivity are discussed.

  12. A hierarchy of thermohaline circulation models. Final report

    SciTech Connect

    Cessi, P.; Young, W.R.

    1998-04-01

    The objectives of this effort were: (1) to understand the variability caused by the competitive roles of salt and heat in the ocean circulation; (2) to understand the effect of differential advection of active tracers, such as temperature, salinity and angular momentum; and (3) to improve the parametrization of convection in models of the ocean circulation. One result of the project is the discovery that the characteristics of the quasi-periodic centennial and millennial oscillations found in OGCM`s, associated with alternating suppression and activation of high latitude convection, are extremely sensitive to the salinity flux and specific choice of convective adjustment scheme. In particular, the period of the oscillation depends crucially on the salinity fluxes (whether deterministic or with a stochastic component) and can be arbitrarily long. This result has clarified that these long-period oscillations (termed flushes) are not the result of the excitation of an intrinsic linear eigenmode of the system, but rather are relaxation-oscillations towards one of the several equilibria available to the system. This implies that it is the amplitude, rather than the period, of the oscillation which is almost independent of the salinity flux.

  13. Advanced Modeling of Micromirror Devices

    NASA Technical Reports Server (NTRS)

    Michalicek, M. Adrian; Sene, Darren E.; Bright, Victor M.

    1995-01-01

    The flexure-beam micromirror device (FBMD) is a phase only piston style spatial light modulator demonstrating properties which can be used for phase adaptive corrective optics. This paper presents a complete study of a square FBMD, from advanced model development through final device testing and model verification. The model relates the electrical and mechanical properties of the device by equating the electrostatic force of a parallel-plate capacitor with the counter-acting spring force of the device's support flexures. The capacitor solution is derived via the Schwartz-Christoffel transformation such that the final solution accounts for non-ideal electric fields. The complete model describes the behavior of any piston-style device, given its design geometry and material properties. It includes operational parameters such as drive frequency and temperature, as well as fringing effects, mirror surface deformations, and cross-talk from neighboring devices. The steps taken to develop this model can be applied to other micromirrors, such as the cantilever and torsion-beam designs, to produce an advanced model for any given device. The micromirror devices studied in this paper were commercially fabricated in a surface micromachining process. A microscope-based laser interferometer is used to test the device in which a beam reflected from the device modulates a fixed reference beam. The mirror displacement is determined from the relative phase which generates a continuous set of data for each selected position on the mirror surface. Plots of this data describe the localized deflection as a function of drive voltage.

  14. Recent advances in the biology of human circulating tumour cells and metastasis

    PubMed Central

    Gkountela, Sofia; Szczerba, Barbara; Donato, Cinzia; Aceto, Nicola

    2016-01-01

    The development of a metastatic disease is recognised as the cause of death of over 90% of patients diagnosed with cancer. Understanding the biological features of metastasis has been hampered for a long time by the difficulties to study widespread cancerous lesions in patients, and by the absence of reliable methods to isolate viable metastatic cells during disease progression. These difficulties negatively impact on our ability to develop new agents that are tailored to block the spread of cancer. Yet, recent advances in specialised devices for the isolation of circulating tumour cells (CTCs), hand-in-hand with technologies that enable single cell resolution interrogation of their genome and transcriptome, are now paving the way to understanding those molecular mechanisms that drive the formation of metastasis. In this review, we aim to summarise some of the latest discoveries in CTC biology in the context of several types of cancer, and to highlight those findings that have a potential to improve the clinical management of patients with metastatic cancer. PMID:27843628

  15. Advanced Mirror & Modelling Technology Development

    NASA Technical Reports Server (NTRS)

    Effinger, Michael; Stahl, H. Philip; Abplanalp, Laura; Maffett, Steven; Egerman, Robert; Eng, Ron; Arnold, William; Mosier, Gary; Blaurock, Carl

    2014-01-01

    The 2020 Decadal technology survey is starting in 2018. Technology on the shelf at that time will help guide selection to future low risk and low cost missions. The Advanced Mirror Technology Development (AMTD) team has identified development priorities based on science goals and engineering requirements for Ultraviolet Optical near-Infrared (UVOIR) missions in order to contribute to the selection process. One key development identified was lightweight mirror fabrication and testing. A monolithic, stacked, deep core mirror was fused and replicated twice to achieve the desired radius of curvature. It was subsequently successfully polished and tested. A recently awarded second phase to the AMTD project will develop larger mirrors to demonstrate the lateral scaling of the deep core mirror technology. Another key development was rapid modeling for the mirror. One model focused on generating optical and structural model results in minutes instead of months. Many variables could be accounted for regarding the core, face plate and back structure details. A portion of a spacecraft model was also developed. The spacecraft model incorporated direct integration to transform optical path difference to Point Spread Function (PSF) and between PSF to modulation transfer function. The second phase to the project will take the results of the rapid mirror modeler and integrate them into the rapid spacecraft modeler.

  16. Modeling of devolatilization in circulating fluidized bed combustion

    SciTech Connect

    Stenseng, M.; Lin, W.; Johnsson, J.E.; Dam-Johansen, K.

    1997-12-31

    A mathematical model is developed to describe the devolatilization process in a circulating fluidized bed combustor. The model is a combination of two submodels: single particle devolatilization and fluid dynamics. The single particle model includes the influence of both chemical kinetics and heat transfer on the rate of devolatilization. The results show a good agreement with literature data. The fluid dynamic model describes the main characteristics of a CFB: a dense zone in the bottom, followed by a splash zone and a dilute zone with a core-annulus structure. Each zone is modeled as a number of CSTR`s and the size and number of CSTR`s has been estimated from tracer experiments in an 80 MW{sub th} CFB boiler. It was not possible to evaluate the model against experimental data, but the dependence of particle size on the degree of devolatilization in the dense bed agrees qualitative with the expected behavior. The mode4l shows that the devolatilization mainly occurs in the dense bed.

  17. De novo sequencing of circulating miRNAs identifies novel markers predicting clinical outcome of locally advanced breast cancer

    PubMed Central

    2012-01-01

    Background MicroRNAs (miRNAs) have been recently detected in the circulation of cancer patients, where they are associated with clinical parameters. Discovery profiling of circulating small RNAs has not been reported in breast cancer (BC), and was carried out in this study to identify blood-based small RNA markers of BC clinical outcome. Methods The pre-treatment sera of 42 stage II-III locally advanced and inflammatory BC patients who received neoadjuvant chemotherapy (NCT) followed by surgical tumor resection were analyzed for marker identification by deep sequencing all circulating small RNAs. An independent validation cohort of 26 stage II-III BC patients was used to assess the power of identified miRNA markers. Results More than 800 miRNA species were detected in the circulation, and observed patterns showed association with histopathological profiles of BC. Groups of circulating miRNAs differentially associated with ER/PR/HER2 status and inflammatory BC were identified. The relative levels of selected miRNAs measured by PCR showed consistency with their abundance determined by deep sequencing. Two circulating miRNAs, miR-375 and miR-122, exhibited strong correlations with clinical outcomes, including NCT response and relapse with metastatic disease. In the validation cohort, higher levels of circulating miR-122 specifically predicted metastatic recurrence in stage II-III BC patients. Conclusions Our study indicates that certain miRNAs can serve as potential blood-based biomarkers for NCT response, and that miR-122 prevalence in the circulation predicts BC metastasis in early-stage patients. These results may allow optimized chemotherapy treatments and preventive anti-metastasis interventions in future clinical applications. PMID:22400902

  18. Modeling Tool Advances Rotorcraft Design

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Continuum Dynamics Inc. (CDI), founded in 1979, specializes in advanced engineering services, including fluid dynamic modeling and analysis for aeronautics research. The company has completed a number of SBIR research projects with NASA, including early rotorcraft work done through Langley Research Center, but more recently, out of Ames Research Center. NASA Small Business Innovation Research (SBIR) grants on helicopter wake modeling resulted in the Comprehensive Hierarchical Aeromechanics Rotorcraft Model (CHARM), a tool for studying helicopter and tiltrotor unsteady free wake modeling, including distributed and integrated loads, and performance prediction. Application of the software code in a blade redesign program for Carson Helicopters, of Perkasie, Pennsylvania, increased the payload and cruise speeds of its S-61 helicopter. Follow-on development resulted in a $24 million revenue increase for Sikorsky Aircraft Corporation, of Stratford, Connecticut, as part of the company's rotor design efforts. Now under continuous development for more than 25 years, CHARM models the complete aerodynamics and dynamics of rotorcraft in general flight conditions. CHARM has been used to model a broad spectrum of rotorcraft attributes, including performance, blade loading, blade-vortex interaction noise, air flow fields, and hub loads. The highly accurate software is currently in use by all major rotorcraft manufacturers, NASA, the U.S. Army, and the U.S. Navy.

  19. Development of a hybrid cloud parameterization for general circulation models

    SciTech Connect

    Kao, C.Y.J.; Kristjansson, J.E.; Langley, D.L.

    1995-04-01

    We have developed a cloud package with state-of-the-art physical schemes that can parameterize low-level stratus or stratocumulus, penetrative cumulus, and high-level cirrus. Such parameterizations will improve cloud simulations in general circulation models (GCMs). The principal tool in this development comprises the physically based Arakawa-Schubert scheme for convective clouds and the Sundqvist scheme for layered, nonconvective clouds. The term {open_quotes}hybrid{close_quotes} addresses the fact that the generation of high-attitude layered clouds can be associated with preexisting convective clouds. Overall, the cloud parameterization package developed should better determine cloud heating and drying effects in the thermodynamic budget, realistic precipitation patterns, cloud coverage and liquid/ice water content for radiation purposes, and the cloud-induced transport and turbulent diffusion for atmospheric trace gases.

  20. Testing Components of New Community Isopycnal Ocean Circulation Model

    SciTech Connect

    Bryan, Kirk

    2008-05-09

    The ocean and atmosphere are both governed by the same physical laws and models of the two media have many similarities. However, there are critical differences that call for special methods to provide the best simulation. One of the most important difference is that the ocean is nearly opaque to radiation in the visible and infra-red part of the spectrum. For this reason water mass properties in the ocean are conserved along trajectories for long distances and for long periods of time. For this reason isopycnal coordinate models would seem to have a distinct advantage in simulating ocean circulation. In such a model the coordinate surfaces are aligned with the natural paths of near adiabatic, density conserving flow in the main thermocline. The difficulty with this approach is at the upper and lower boundaries of the ocean, which in general do not coincide with density surfaces. For this reason hybrid coordinate models were proposed by Bleck and Boudra (1981) in which Cartesian coordinates were used near the ocean surface and isopycnal coordinates were used in the main thermocline. This feature is now part of the HICOM model (Bleck, 2002).

  1. Sensitivity simulations of superparameterised convection in a general circulation model

    NASA Astrophysics Data System (ADS)

    Rybka, Harald; Tost, Holger

    2015-04-01

    Cloud Resolving Models (CRMs) covering a horizontal grid spacing from a few hundred meters up to a few kilometers have been used to explicitly resolve small-scale and mesoscale processes. Special attention has been paid to realistically represent cloud dynamics and cloud microphysics involving cloud droplets, ice crystals, graupel and aerosols. The entire variety of physical processes on the small-scale interacts with the larger-scale circulation and has to be parameterised on the coarse grid of a general circulation model (GCM). Since more than a decade an approach to connect these two types of models which act on different scales has been developed to resolve cloud processes and their interactions with the large-scale flow. The concept is to use an ensemble of CRM grid cells in a 2D or 3D configuration in each grid cell of the GCM to explicitly represent small-scale processes avoiding the use of convection and large-scale cloud parameterisations which are a major source for uncertainties regarding clouds. The idea is commonly known as superparameterisation or cloud-resolving convection parameterisation. This study presents different simulations of an adapted Earth System Model (ESM) connected to a CRM which acts as a superparameterisation. Simulations have been performed with the ECHAM/MESSy atmospheric chemistry (EMAC) model comparing conventional GCM runs (including convection and large-scale cloud parameterisations) with the improved superparameterised EMAC (SP-EMAC) modeling one year with prescribed sea surface temperatures and sea ice content. The sensitivity of atmospheric temperature, precipiation patterns, cloud amount and types is observed changing the embedded CRM represenation (orientation, width, no. of CRM cells, 2D vs. 3D). Additionally, we also evaluate the radiation balance with the new model configuration, and systematically analyse the impact of tunable parameters on the radiation budget and hydrological cycle. Furthermore, the subgrid

  2. The circulation of Icelandic waters - a modelling study

    NASA Astrophysics Data System (ADS)

    Logemann, K.; Ólafsson, J.; Snorrason, Á.; Valdimarsson, H.; Marteinsdóttir, G.

    2013-04-01

    The three-dimensional flow, temperature and salinity fields of the North Atlantic including the Arctic Ocean covering the time period 1992 to 2006 are simulated with the numerical ocean model CODE. The model reveals several new insights and previously unknown structures which help us to clarify open questions on the regional oceanography of Icelandic waters. These relate to the structure and geographical distribution of the coastal current, the primary forcing of the North Icelandic Irminger Current (NIIC), the path of the Atlantic Water south-east of Iceland and the structure of the North Icelandic Jet (NIJ). The model's adaptively refined computational mesh has a maximum resolution of 1 km horizontal and 2.5 m vertical in Icelandic waters. CTD profiles from this region and the river discharge of 46 Icelandic watersheds, computed by the hydrological model WaSiM, are assimilated into the simulation. The model realistically reproduces the established elements of the circulation around Iceland. However, analysis of the simulated mean flow field also provides further insights. It suggests a distinct freshwater-induced coastal current that only exists along the south-west and west coasts which is accompanied by a counter-directed undercurrent. The simulated transport of Atlantic Water over the Icelandic shelf takes place in a symmetrical system of two currents, with the established NIIC over the north-western and northern shelf, and a current over the southern and south-eastern shelf herein called the South Icelandic Current (SIC). Both currents are driven by topographically induced distortions of the Arctic Front's barotropic pressure field. The SIC is simulated to be an upstream precursor of the Faroe Current (FC). The recently discovered North Icelandic Jet (NIJ) also features in the model predictions and is found to be forced by the baroclinic pressure field of the Arctic Front, to originate east of the Kolbeinsey Ridge and to have a volume transport of around 1

  3. Venusian Polar Vortex reproduced by a general circulation model

    NASA Astrophysics Data System (ADS)

    Ando, Hiroki; Sugimoto, Norihiko; Takagi, Masahiro

    2016-10-01

    Unlike the polar vortices observed in the Earth, Mars and Titan atmospheres, the observed Venus polar vortex is warmer than the mid-latitudes at cloud-top levels (~65 km). This warm polar vortex is zonally surrounded by a cold latitude band located at ~60 degree latitude, which is a unique feature called 'cold collar' in the Venus atmosphere [e.g. Taylor et al. 1980; Piccioni et al. 2007]. Although these structures have been observed in numerous previous observations, the formation mechanism is still unknown. In addition, an axi-asymmetric feature is always seen in the warm polar vortex. It changes temporally and sometimes shows a hot polar dipole or S-shaped structure as shown by a lot of infrared measurements [e.g. Garate-Lopez et al. 2013; 2015]. However, its vertical structure has not been investigated. To solve these problems, we performed a numerical simulation of the Venus atmospheric circulation using a general circulation model named AFES for Venus [Sugimoto et al. 2014] and reproduced these puzzling features.And then, the reproduced structures of the atmosphere and the axi-asymmetirc feature are compared with some previous observational results.In addition, the quasi-periodical zonal-mean zonal wind fluctuation is also seen in the Venus polar vortex reproduced in our model. This might be able to explain some observational results [e.g. Luz et al. 2007] and implies that the polar vacillation might also occur in the Venus atmosphere, which is silimar to the Earth's polar atmosphere. We will also show some initial results about this point in this presentation.

  4. Modelling ocean circulation in Deep-ocean aquaplanets

    NASA Astrophysics Data System (ADS)

    McKinstry, A.

    2012-04-01

    Léger et al. (2004) and Küchner (2003) hypothesised that Ocean planets, Super-Earth planets with liquid-water oceans covering their whole surfaces may exist. Planets with liquid water surfaces could have ocean depths of 70-100 km with bottom pressures of 1-5 GPa. To date, no general circulation models have been run on such oceans, primarily because of a lack of equation of state for seawater at such depths. In this work a deep-water seawater Equation of State is implemented in the MITgcm ocean model. The EOS depends not only on the salinity and temperature but also on CO2 concentration. Several proposed ocean compositions, in particular magnesium and sodium sulphates salts ,H2O / ammonia mixes are investigated. While geothermal plumes in pure water systems will rise through an the whole ocean depths, saline-enriched plumes do not, due to differential thermal expansions for saline fluids leading to a loss of buoyancy (Melosh et al., 2004). Vance and Brown (2005) have shown that double-diffusive convection is expected to be a significant feature of such high-pressure oceans: depending on ocean composition, a double-diffusive layer will frustrate deep ocean convective processes and hence heat transfer. Convection happens separately in the warm, saline layers below and cooler, more dilute layer above. While this has been seen in isolated areas on Earth, such as the Red Sea, we explore the effects of heat and salin transfer through this layer on global circulation for deep ocean planet.

  5. The circulation of Icelandic waters - a modelling study

    NASA Astrophysics Data System (ADS)

    Logemann, K.; Ólafsson, J.; Snorrason, Á.; Valdimarsson, H.; Marteinsdóttir, G.

    2013-10-01

    The three-dimensional flow, temperature and salinity fields of the North Atlantic, including the Arctic Ocean, covering the time period 1992 to 2006 are simulated with the numerical ocean model CODE. The simulation reveals several new insights and previously unknown structures which help us to clarify open questions on the regional oceanography of Icelandic waters. These relate to the structure and geographical distribution of the coastal current, the primary forcing of the North Icelandic Irminger Current (NIIC) and the path of the Atlantic Water south-east of Iceland. The model's adaptively refined computational mesh has a maximum resolution of 1 km horizontal and 2.5 m vertical in Icelandic waters. CTD profiles from this region and the river discharge of 46 Icelandic watersheds, computed by the hydrological model WaSiM, are assimilated into the simulation. The model realistically reproduces the established elements of the circulation around Iceland. However, analysis of the simulated mean flow field also provides further insights. It suggests a distinct freshwater-induced coastal current that only exists along the south-west and west coasts, which is accompanied by a counter-directed undercurrent. The simulated transport of Atlantic Water over the Icelandic shelf takes place in a symmetrical system of two currents, with the established NIIC over the north-western and northern shelf, and a hitherto unnamed current over the southern and south-eastern shelf, which is simulated to be an upstream precursor of the Faroe Current (FC). Both currents are driven by barotropic pressure gradients induced by a sea level slope across the Greenland-Scotland Ridge. The recently discovered North Icelandic Jet (NIJ) also features in the model predictions and is found to be forced by the baroclinic pressure field of the Arctic Front, to originate east of the Kolbeinsey Ridge and to have a volume transport of around 1.5 Sv within northern Denmark Strait. The simulated multi

  6. Abnormal arterial flows by a distributed model of the fetal circulation.

    PubMed

    van den Wijngaard, Jeroen P H M; Westerhof, Berend E; Faber, Dirk J; Ramsay, Margaret M; Westerhof, Nico; van Gemert, Martin J C

    2006-11-01

    Modeling the propagation of blood pressure and flow along the fetoplacental arterial tree may improve interpretation of abnormal flow velocity waveforms in fetuses. The current models, however, either do not include a wide range of gestational ages or do not account for variation in anatomical, vascular, or rheological parameters. We developed a mathematical model of the pulsating fetoumbilical arterial circulation using Womersley's oscillatory flow theory and viscoelastic arterial wall properties. Arterial flow waves are calculated at different arterial locations from which the pulsatility index (PI) can be determined. We varied blood viscosity, placental and brain resistances, placental compliance, heart rate, stiffness of the arterial wall, and length of the umbilical arteries. The PI increases in the umbilical artery and decreases in the cerebral arteries, as a result of increasing placental resistance or decreasing brain resistance. Both changes in resistance decrease the flow through the placenta. An increased arterial stiffness increases the PIs in the entire fetoplacental circulation. Blood viscosity and peripheral bed compliance have limited influence on the flow profiles. Bradycardia and tachycardia increase and decrease the PI in all arteries, respectively. Umbilical arterial length has limited influence on the PI but affects the mean arterial pressure at the placental cord insertion. The model may improve the interpretation of arterial flow pulsations and thus may advance both the understanding of pathophysiological processes and clinical management.

  7. Limited genomic heterogeneity of circulating melanoma cells in advanced stage patients.

    PubMed

    Ruiz, Carmen; Li, Julia; Luttgen, Madelyn S; Kolatkar, Anand; Kendall, Jude T; Flores, Edna; Topp, Zheng; Samlowski, Wolfram E; McClay, Edward; Bethel, Kelly; Ferrone, Soldano; Hicks, James; Kuhn, Peter

    2015-01-09

    Purpose. Circulating melanoma cells (CMCs) constitute a potentially important representation of time-resolved tumor biology in patients. To date, genomic characterization of CMCs has been limited due to the lack of a robust methodology capable of identifying them in a format suitable for downstream characterization. Here, we have developed a methodology to detect intact CMCs that enables phenotypic, morphometric and genomic analysis at the single cell level. Experimental design. Blood samples from 40 metastatic melanoma patients and 10 normal blood donors were prospectively collected. A panel of 7 chondroitin sulfate proteoglycan 4 (CSPG4)-specific monoclonal antibodies (mAbs) was used to immunocytochemically label CMCs. Detection was performed by automated digital fluorescence microscopy and multi-parametric computational analysis. Individual CMCs were captured by micromanipulation for whole genome amplification and copy number variation (CNV) analysis. Results. Based on CSPG4 expression and nuclear size, 1-250 CMCs were detected in 22 (55%) of 40 metastatic melanoma patients (0.5-371.5 CMCs ml(-1)). Morphometric analysis revealed that CMCs have a broad spectrum of morphologies and sizes but exhibit a relatively homogeneous nuclear size that was on average 1.5-fold larger than that of surrounding PBMCs. CNV analysis of single CMCs identified deletions of CDKN2A and PTEN, and amplification(s) of TERT, BRAF, KRAS and MDM2. Furthermore, novel chromosomal amplifications in chr12, 17 and 19 were also found. Conclusions. Our findings show that CSPG4 expressing CMCs can be found in the majority of advanced melanoma patients. High content analysis of this cell population may contribute to the design of effective personalized therapies in patients with melanoma.

  8. Prognostic value of circulating tumor cells in advanced gastric cancer patients receiving chemotherapy

    PubMed Central

    Liu, Yongping; Ling, Yang; Qi, Qiufeng; Lan, Feng; Zhu, Ming; Zhang, Yaping; Bao, Yanqing; Zhang, Changsong

    2017-01-01

    The identification of circulating tumor cells (CTCs) may provide important prognostic information in several types of solid tumors, including gastric cancer. The aim of this study was to investigate whether CTC count may be used to predict survival in patients with advanced gastric cancer treated with chemotherapy. The CELLection™ Epithelial Enrich kit was used to isolate and purify CTCs from samples of peripheral blood. Immunofluorescent staining was used for CTC counting. High CTC counts were associated with poor tumor differentiation and high serum CEA levels (P=0.021 and 0.005, respectively). After 3 months, 16 patients with decreasing CTC counts after the first cycle of chemotherapy obtained complete response, partial response or stable disease, while 13 patients with increasing CTC counts developed progressive disease. The patients with decreasing CTC counts also exhibited longer progression-free survival (PFS) (P≤0.001) and overall survival (OS) (P=0.002) compared with those with increasing CTC counts. Among all 59 patients, those with a CTC count of ≤2 cells/5 ml blood exhibited longer PFS (P≤0.001) and OS (P≤0.001) compared with those with a CTC count of >2 cells/5 ml blood. The multivariate analysis suggested that an increase of the CTC count after the first cycle of chemotherapy was only an independent prognostic marker of poor PFS (P=0.019). However, a baseline CTC count of >2 cells/5 ml blood was an independent poor prognostic marker for PFS (P=0.008) and OS (P=0.001) in all 59 patients. Our study suggested that patients with a low baseline CTC count or decrease of the CTC count after the first cycle of chemotherapy may benefit significantly from palliative chemotherapy. In conclusion, CTC count may be a good chemotherapy monitoring marker and an ideal prognostic marker for patients receiving palliative chemotherapy. PMID:28357102

  9. Limited Genomic Heterogeneity of Circulating Melanoma Cells in Advanced Stage Patients

    PubMed Central

    Ruiz, Carmen; Li, Julia; Luttgen, Madelyn S.; Kolatkar, Anand; Kendall, Jude T.; Flores, Edna; Topp, Zheng; Samlowski, Wolfram E.; McClay, Ed; Bethel, Kelly; Ferrone, Soldano; Hicks, James; Kuhn, Peter

    2015-01-01

    Purpose Circulating melanoma cells (CMCs) constitute a potentially important representation of time-resolved tumor biology in patients. To date, genomic characterization of CMCs has been limited due to the lack of a robust methodology capable of identifying them in a format suitable for downstream characterization. Here, we have developed a methodology to detect intact CMCs that enables phenotypic, morphometric and genomic analysis at the single cell level. Experimental design Blood samples from 40 metastatic melanoma patients and 10 normal blood donors (NBD) were prospectively collected. A panel of 7 chondroitin sulfate proteoglycan 4 (CSPG4)-specific monoclonal antibodies (mAb) was used to immunocytochemically label CMCs. Detection was performed by automated digital fluorescence microscopy and multi-parametric computational analysis. Individual CMCs were captured by micromanipulation for whole genome amplification (WGA) and copy number variation (CNV) analysis. Results Based on CSPG4 expression and nuclear size, 1 to 250 CMCs were detected in 22 (55%) of 40 metastatic melanoma patients (0.5 to 371.5 CMCs/ml). Morphometric analysis revealed that CMCs have a broad spectrum of morphologies and sizes but exhibit a relatively homogeneous nuclear size that was on average 1.5-fold larger than that of surrounding PBMCs. CNV analysis of single CMCs identified deletions of CDKN2A and PTEN, and amplification(s) of TERT, BRAF, KRAS and MDM2. Furthermore, novel chromosomal amplifications in chr12, 17 and 19 were also found. Conclusions Our findings show that CSPG4 expressing CMCs can be found in the majority of advanced melanoma patients. High content analysis of this population may contribute to develop effective therapeutic strategies. PMID:25574741

  10. Limited genomic heterogeneity of circulating melanoma cells in advanced stage patients

    NASA Astrophysics Data System (ADS)

    Ruiz, Carmen; Li, Julia; Luttgen, Madelyn S.; Kolatkar, Anand; Kendall, Jude T.; Flores, Edna; Topp, Zheng; Samlowski, Wolfram E.; McClay, Edward; Bethel, Kelly; Ferrone, Soldano; Hicks, James; Kuhn, Peter

    2015-02-01

    Purpose. Circulating melanoma cells (CMCs) constitute a potentially important representation of time-resolved tumor biology in patients. To date, genomic characterization of CMCs has been limited due to the lack of a robust methodology capable of identifying them in a format suitable for downstream characterization. Here, we have developed a methodology to detect intact CMCs that enables phenotypic, morphometric and genomic analysis at the single cell level. Experimental design. Blood samples from 40 metastatic melanoma patients and 10 normal blood donors were prospectively collected. A panel of 7 chondroitin sulfate proteoglycan 4 (CSPG4)-specific monoclonal antibodies (mAbs) was used to immunocytochemically label CMCs. Detection was performed by automated digital fluorescence microscopy and multi-parametric computational analysis. Individual CMCs were captured by micromanipulation for whole genome amplification and copy number variation (CNV) analysis. Results. Based on CSPG4 expression and nuclear size, 1-250 CMCs were detected in 22 (55%) of 40 metastatic melanoma patients (0.5-371.5 CMCs ml-1). Morphometric analysis revealed that CMCs have a broad spectrum of morphologies and sizes but exhibit a relatively homogeneous nuclear size that was on average 1.5-fold larger than that of surrounding PBMCs. CNV analysis of single CMCs identified deletions of CDKN2A and PTEN, and amplification(s) of TERT, BRAF, KRAS and MDM2. Furthermore, novel chromosomal amplifications in chr12, 17 and 19 were also found. Conclusions. Our findings show that CSPG4 expressing CMCs can be found in the majority of advanced melanoma patients. High content analysis of this cell population may contribute to the design of effective personalized therapies in patients with melanoma.

  11. Correcting precipitation feature location in general circulation models

    NASA Astrophysics Data System (ADS)

    Levy, Adam A. L.; Jenkinson, Mark; Ingram, William; Allen, Myles

    2014-12-01

    There is much evidence that precipitation responses to global warming involve wet regions becoming wetter and dry regions drier. This presents challenges for the interpretation of projections from general circulation models (GCMs) which have substantial biases in the location of precipitation features. While improving GCM simulated precipitation is the most desirable solution, adaptation and mitigation decisions must be made with the models already available. Many techniques have been developed to correct biases in grid point precipitation intensities, but few have been introduced to correct for location biases. Here, we describe a new technique for correcting the spatial and seasonal location of climatological precipitation features. We design this technique to respect the geometry of the problem (spherical spatial dimensions, with cyclic seasons), while conserving either precipitation intensities, or integrated precipitation amount. We discuss the mathematical basis of the technique and investigate its behaviour in different regimes. We find that the resulting warps depend smoothly on the most influential parameter, which determines the balance between smoothness and closeness of fit. We show that the technique is capable of removing more than half the RMS error in a model's climatology, obtaining consistently better results when conserving integrated precipitation. To demonstrate the ability of the new technique to improve simulated precipitation changes, we apply our transformations to historical anomalies and show that RMS error is reduced relative to GPCP's anomalies by approximately 10% for both types of warp. This verifies that errors in precipitation changes can be reduced by correcting underlying location errors in a GCM's climatology.

  12. A bulk cloud parameterization in a Venus General Circulation Model

    NASA Astrophysics Data System (ADS)

    Lee, Christopher; Lewis, Stephen R.; Read, Peter L.

    2010-04-01

    A condensing cloud parameterization is included in a super-rotating Venus General Circulation Model. A parameterization including condensation, evaporation and sedimentation of mono-modal sulfuric acid cloud particles is described. Saturation vapor pressure of sulfuric acid vapor is used to determine cloud formation through instantaneous condensation and destruction through evaporation, while pressure dependent viscosity of a carbon dioxide atmosphere is used to determine sedimentation rates assuming particles fall at their terminal Stokes velocity. Modifications are described to account for the large range of the Reynolds number seen in the Venus atmosphere. Two GCM experiments initialized with 10 ppm-equivalent of sulfuric acid are integrated for 30 Earth years and the results are discussed with reference to "Y" shaped cloud structures observed on Venus. The GCM is able to produce an analog of the "Y" shaped cloud structure through dynamical processes alone, with contributions from the mean westward wind, the equatorial Kelvin wave, and the mid-latitude/polar Mixed Rossby/Gravity waves. The cloud top height in the GCM decreases from equator to pole and latitudinal gradients of cloud top height are comparable to those observed by Pioneer Venus and Venus Express, and those produced in more complex microphysical models of the sulfur cycle on Venus. Differences between the modeled cloud structures and observations are described and dynamical explanations are suggested for the most prominent differences.

  13. A new solar cycle model including meridional circulation

    NASA Technical Reports Server (NTRS)

    Wang, Y.-M.; Sheeley, N. R., Jr.; Nash, A. G.

    1991-01-01

    A kinematic model is presented for the solar cycle which includes not only the transport of magnetic flux by supergranular diffusion and a poleward bulk flow at the sun's surface, but also the effects of turbulent diffusion and an equatorward 'return flow' beneath the surface. As in the earlier models of Babcock and Leighton, the rotational shearing of a subsurface poloidal field generates toroidal flux that erupts at the surface in the form of bipolar magnetic regions. However, such eruptions do not result in any net loss of toroidal flux from the sun (as assumed by Babcock and Leighton); instead, the large-scale toroidal field is destroyed both by 'unwinding' as the local poloidal field reverses its polarity, and by diffusion as the toroidal flux is transported equatorward by the subsurface flow and merged with its opposite hemisphere counterpart. The inclusion of meridional circulation allows stable oscillations of the magnetic field, accompanied by the equatorward progression of flux eruptions, to be achieved even in the absence of a radial gradient in the angular velocity. An illustrative case in which a subsurface flow speed of order 1 m/s and subsurface diffusion rate of order 10 sq km/s yield 22-yr oscillations in qualitative agreement with observations.

  14. Hospitable archean climates simulated by a general circulation model.

    PubMed

    Wolf, E T; Toon, O B

    2013-07-01

    Evidence from ancient sediments indicates that liquid water and primitive life were present during the Archean despite the faint young Sun. To date, studies of Archean climate typically utilize simplified one-dimensional models that ignore clouds and ice. Here, we use an atmospheric general circulation model coupled to a mixed-layer ocean model to simulate the climate circa 2.8 billion years ago when the Sun was 20% dimmer than it is today. Surface properties are assumed to be equal to those of the present day, while ocean heat transport varies as a function of sea ice extent. Present climate is duplicated with 0.06 bar of CO2 or alternatively with 0.02 bar of CO2 and 0.001 bar of CH4. Hot Archean climates, as implied by some isotopic reconstructions of ancient marine cherts, are unattainable even in our warmest simulation having 0.2 bar of CO2 and 0.001 bar of CH4. However, cooler climates with significant polar ice, but still dominated by open ocean, can be maintained with modest greenhouse gas amounts, posing no contradiction with CO2 constraints deduced from paleosols or with practical limitations on CH4 due to the formation of optically thick organic hazes. Our results indicate that a weak version of the faint young Sun paradox, requiring only that some portion of the planet's surface maintain liquid water, may be resolved with moderate greenhouse gas inventories. Thus, hospitable late Archean climates are easily obtained in our climate model.

  15. Numerical Modelling of Circulation and Exchange through Singapore Straits

    NASA Astrophysics Data System (ADS)

    Liu, G.; Xu, M.; Chua, V. P.

    2014-12-01

    The circulation in the Singapore coastal region is complicated and influenced by the combination of tidal forcing of the surrounding seas, complex bathymetry, irregular coastlines, and seasonal monsoon and local winds. An unstructured-grid SUNTANS (Stanford Unstructured Nonhydrostatic Terrain-following Adaptive Navier-Stokes Simulator) model is employed to perform three-dimensional simulations of flow in Singapore coastal waters. The unstructured-grid has an average resolution of 50 - 100 m around Singapore and in areas close to the shoreline, while a coarse grid resolution is employed in the open waters. The model is tidally forced at the three open boundaries, located to the west, south and east of Singapore, using the 8 main tidal constituents as derived from the OSU Tidal Prediction Software (OTPS). A detailed calibration is performed, and the model-predicted water levels and currents compare well with observed data throughout the model domain. We examine the individual and combined effects of tidal and wind forcing by performing simulations with (1) tides only, (2) winds only and (3) both tides and wind. The exchange through Singapore Strait is investigated by computing volume fluxes and transport pathways at four transects, namely the Malacca Strait, Java Sea, South China Sea and Singapore transects. The transport pathways are computed by releasing particles on each side of the transects, and identifying the spatial distribution of the particles over one tidal cycle. Our results show that tidal forcing is predominant in Singapore Strait, and wind forcing is an important mechanism during the monsoon season. The residual effects, attributed to nonlinear interactions between tidal and wind forcing, is dominant during the inter-monsoon season.

  16. Serum cytokines are increased and circulating micronutrients are not altered in subjects with early compared to advanced knee osteoarthritis.

    PubMed

    Barker, Tyler; Rogers, Victoria E; Henriksen, Vanessa T; Aguirre, Dale; Trawick, Roy H; Rasmussen, G Lynn; Momberger, Nathan G

    2014-08-01

    Knee osteoarthritis (OA) is a leading cause of physical disability. At the early stage of knee OA, the increase in synovial fluid cytokine concentrations could contribute to the pathogenesis of OA by degrading articular cartilage. It is unknown, however, if inflammatory cytokines increase systemically at the early or advanced stage of knee OA. The systemic increase of inflammatory cytokines could be detrimental to the endogenous status of micronutrients that protect against excessive inflammation and cytokine-mediated events. The purpose of this study was to test the hypothesis that an increase in serum cytokines associate with a decrease in circulating micronutrients in subjects with early compared to advanced knee OA. Advanced knee OA subjects (n=14) displayed radiographic, pain, and muscular weakness symptoms of knee OA. Early knee OA subjects (n=14) were matched (age, gender, and body mass index) to the advanced OA group and displayed one or two of the aforementioned symptoms of knee OA. Inflammatory cytokines, vitamins C (ascorbic acid), D (25-hydroxyvitamin D), and E (α- and γ-tocopherols), and β-carotene were measured in fasting blood samples. In the early OA group, serum tumor necrosis factor (TNF)-α, interleukin (IL)-5, IL-6, IL-12, and IL-13 concentrations were significantly (all p<0.05) increased. Circulating ascorbic acid, 25-hydroxyvitamin D, α- and γ-tocopherol's, and β-carotene concentrations were not significantly different between groups. Based on these preliminary results, we conclude that the systemic increase of inflammatory cytokines is not associated with a decrease in circulating micronutrients in subjects with early compared to advanced knee OA.

  17. Jet streak circulations associated with a moderate snowfall event as diagnosed from NGM model output. [Nested Grid Model

    NASA Technical Reports Server (NTRS)

    Kocin, Paul J.; Uccellini, Louis W.; Skillman, William C.; Grumm, Richard H.

    1989-01-01

    The existence, evolution, and interaction of vertical circulations associated with upper-level jet streaks during a moderate snowfall event are diagnosed using a nested grid model (NGM). The event itself is overviewed, and the diagnosis of transverse circulations utilizing NGM output is discussed. Focus is placed on the identification of the horizontal and vertical components of the circulation, the temporal evolution of the circulation, and the comparison of the circulation from successive model forecasts. A preliminary analysis of the model data indicates that the horizontal and vertical branches of the circulations can be diagnosed from the model output, and the horizontal and vertical components of the circulations may be identified and followed during an individual forecast cycle.

  18. Late Early Silurian (Wenlockian) paleoclimate using a general circulation model

    SciTech Connect

    Moore, G.T.; Hayashida, D.N.; Jacobson, S.R. ) Ross, C.A. )

    1992-01-01

    The Silurian Period (439--409 Ma) is synonymous with organic-rich, graptolitic, black shales. The physical conditions that prevailed during the Mid-Silurian drove the paleoclimate and controlled the deposition of this globally ubiquitous, lithotope. The paleoclimate in turn concomitantly created a paleoceanic environment favorable for the generation, deposition, and preservation of phytoplankton. A study of the relationship of the paleogeographic framework on the paleoclimate conditions that forced the deposition of this unique rock type is a problem suitable for study with a general circulation model. For this study the authors chose the Wenlockian Stage (430--424 Ma), the late Early Silurian. The Wenlockian physical world was composed of an oceanic northern hemisphere and a southern hemisphere dominated by the giant continent of Gondwana. The high latitude position of Gondwana placed much of its extensive margin in the mid-latitudes. Laurentia and Baltica occupied a tropical position while Siberia and Kazakh laid to the north. The Silurian fits a paleoatmosphere with an elevated greenhouse effect. Estimated Silurian values of atmospheric CO[sub 2] vary. They chose 1,120 ppm CO[sub 2], a value of 4[times] that of the pre-industrial level. The overall paleoclimate is forced by the diverse paleogeography of the two hemispheres. The northern hemisphere is dominated by strong zonality in all seasons. In contrast, the continental southern hemisphere reactors to the summer heating and winter cooling of Gondwana.

  19. Examination of Ventricular Contraction Function Using Electrical Lumped Circuit Model of Circulation System

    NASA Astrophysics Data System (ADS)

    Ito, Mitsuyo; Koya, Yoshiharu; Mizoshiri, Isao

    Presently, many of the already proposed blood circulation models are mainly partial models although they are precise models. A complete model that is a combination of these partial models are difficult to analyze because it is complicated to consider both the viscosity of blood and circulatory details at the same time. So, it is difficult to control the model parameters in order to adapt to various cases of circulatory diseases. This paper proposes a complete circulation model as a lumped electrical circuit, which is comparatively simple. In the circuit model, total blood is modeled as seven lumped capacitors, representing the functions of atriums, ventricles, arteries, veins and lungs. We regard the variation of the ventricle capacitance as the driving force of the complete circulation model. In our model, we considered only the variation of pressure between each part and the blood capacity of each part. In particular, the contraction function of the left ventricle is examined under the consideration of whole blood circulation.

  20. Mathematical modeling of the circulation in the liver lobule.

    PubMed

    Bonfiglio, Andrea; Leungchavaphongse, Kritsada; Repetto, Rodolfo; Siggers, Jennifer H

    2010-11-01

    In this paper, we develop a mathematical model of blood circulation in the liver lobule. We aim to find the pressure and flux distributions within a liver lobule. We also investigate the effects of changes in pressure that occur following a resection of part of the liver, which often leads to high pressure in the portal vein. The liver can be divided into functional units called lobules. Each lobule has a hexagonal cross-section, and we assume that its longitudinal extent is large compared with its width. We consider an infinite lattice of identical lobules and study the two-dimensional flow in the hexagonal cross-sections. We model the sinusoidal space as a porous medium, with blood entering from the portal tracts (located at each of the vertices of the cross-section of the lobule) and exiting via the centrilobular vein (located in the center of the cross-section). We first develop and solve an idealized mathematical model, treating the porous medium as rigid and isotropic and blood as a Newtonian fluid. The pressure drop across the lobule and the flux of blood through the lobule are proportional to one another. In spite of its simplicity, the model gives insight into the real pressure and velocity distribution in the lobule. We then consider three modifications of the model that are designed to make it more realistic. In the first modification, we account for the fact that the sinusoids tend to be preferentially aligned in the direction of the centrilobular vein by considering an anisotropic porous medium. In the second, we account more accurately for the true behavior of the blood by using a shear-thinning model. We show that both these modifications have a small quantitative effect on the behavior but no qualitative effect. The motivation for the final modification is to understand what happens either after a partial resection of the liver or after an implantation of a liver of small size. In these cases, the pressure is observed to rise significantly, which

  1. Adaptive Error Estimation in Linearized Ocean General Circulation Models

    NASA Technical Reports Server (NTRS)

    Chechelnitsky, Michael Y.

    1999-01-01

    Data assimilation methods are routinely used in oceanography. The statistics of the model and measurement errors need to be specified a priori. This study addresses the problem of estimating model and measurement error statistics from observations. We start by testing innovation based methods of adaptive error estimation with low-dimensional models in the North Pacific (5-60 deg N, 132-252 deg E) to TOPEX/POSEIDON (TIP) sea level anomaly data, acoustic tomography data from the ATOC project, and the MIT General Circulation Model (GCM). A reduced state linear model that describes large scale internal (baroclinic) error dynamics is used. The methods are shown to be sensitive to the initial guess for the error statistics and the type of observations. A new off-line approach is developed, the covariance matching approach (CMA), where covariance matrices of model-data residuals are "matched" to their theoretical expectations using familiar least squares methods. This method uses observations directly instead of the innovations sequence and is shown to be related to the MT method and the method of Fu et al. (1993). Twin experiments using the same linearized MIT GCM suggest that altimetric data are ill-suited to the estimation of internal GCM errors, but that such estimates can in theory be obtained using acoustic data. The CMA is then applied to T/P sea level anomaly data and a linearization of a global GFDL GCM which uses two vertical modes. We show that the CMA method can be used with a global model and a global data set, and that the estimates of the error statistics are robust. We show that the fraction of the GCM-T/P residual variance explained by the model error is larger than that derived in Fukumori et al.(1999) with the method of Fu et al.(1993). Most of the model error is explained by the barotropic mode. However, we find that impact of the change in the error statistics on the data assimilation estimates is very small. This is explained by the large

  2. Advances in Watershed Models and Modeling

    NASA Astrophysics Data System (ADS)

    Yeh, G. T.; Zhang, F.

    2015-12-01

    The development of watershed models and their applications to real-world problems has evolved significantly since 1960's. Watershed models can be classified based on what media are included, what processes are dealt with, and what approaches are taken. In term of media, a watershed may include segregated overland regime, river-canal-open channel networks, ponds-reservoirs-small lakes, and subsurface media. It may also include integrated media of all these or a partial set of these as well as man-made control structures. In term of processes, a watershed model may deal with coupled or decoupled hydrological and biogeochemical cycles. These processes include fluid flow, thermal transport, salinity transport, sediment transport, reactive transport, and biota and microbe kinetics. In terms of approaches, either parametric or physics-based approach can be taken. This talk discusses the evolution of watershed models in the past sixty years. The advances of watershed models center around their increasing design capability to foster these segregated or integrated media and coupled or decoupled processes. Widely used models developed by academia, research institutes, government agencies, and private industries will be reviewed in terms of the media and processes included as well as approaches taken. Many types of potential benchmark problems in general can be proposed and will be discussed. This presentation will focus on three benchmark problems of biogeochemical cycles. These three problems, dealing with water quality transport, will be formulated in terms of reactive transport. Simulation results will be illustrated using WASH123D, a watershed model developed and continuously updated by the author and his PhD graduates. Keywords: Hydrological Cycles, Biogeochemical Cycles, Biota Kinetics, Parametric Approach, Physics-based Approach, Reactive Transport.

  3. Influence of land surface roughness on atmospheric circulation and precipitation - A sensitivity study with a general circulation model

    NASA Technical Reports Server (NTRS)

    Sud, Y. C.; Shukla, J.; Mintz, Y.

    1988-01-01

    The influence of land surface roughness on the large scale atmospheric circulation and rainfall is examined by comparing three sets of simulations made with a general circulation model in which the land surface roughness length, z(0), was reduced from 45 cm to 0.02 cm. It is found that the reduced surface roughness produced a two-fold increase in the boundary layer wind speed, a two-fold decrease in the magnitude of the surface stress, and almost no change in the surface evaporation and surface sensible heat flux. It is suggested that the height of the earth's vegetation cover has a large influence on the boundary layer water vapor transport convergence and the rainfall distribution.

  4. Documentation of the GLAS fourth order general circulation model. Volume 1: Model documentation

    NASA Technical Reports Server (NTRS)

    Kalnay, E.; Balgovind, R.; Chao, W.; Edelmann, J.; Pfaendtner, J.; Takacs, L.; Takano, K.

    1983-01-01

    The volume 1, of a 3 volume technical memoranda which contains a documentation of the GLAS Fourth Order General Circulation Model is presented. Volume 1 contains the documentation, description of the stratospheric/tropospheric extension, user's guide, climatological boundary data, and some climate simulation studies.

  5. Numerical modelling of geothermal and reflux circulation in Enewetak Atoll: Implications for dolomitization

    USGS Publications Warehouse

    Jones, G.; Whitaker, F.; Smart, P.; Sanford, W.

    2000-01-01

    Two types of regional-scale seawater circulation have been proposed to explain the formation of Enewetak Atoll dolomites: geothermal and reflux circulation. We have used a finite element groundwater flow model to examine the pattern, magnitude and dynamic interaction of these two different circulation mechanisms in Enewetak Atoll. Geothermal circulation is concentrated around the atoll-margin whereas refluxing mesosaline brines flow from the atoll interior towards the margin to restrict and eventually shut off geothermal circulation. Refluxing brines of 36-80??? can account for the salinity signature recorded in dolomite fluid inclusions. Distributions of fluid flux and Mg mass-balance calculations suggest that both geothermal and reflux circulation mechanisms could account for the observed distribution of dolomite in Enewetak Atoll. Furthermore, the atoll interior may be extensively dolomitized as observed in other atolls. (C) 2000 Elsevier Science B.V. All rights reserved.Two types of regional-scale seawater circulation have been proposed to explain the formation of Enewetak Atoll dolomites: geothermal and reflux circulation. We have used a finite element groundwater flow model to examine the pattern, magnitude and dynamic interaction of these two different circulation mechanisms in Enewetak Atoll. Geothermal circulation is concentrated around the atoll-margin whereas refluxing mesosaline brines flow from the atoll interior towards the margin to restrict and eventually shut off geothermal circulation. Refluxing brines of 36-80 per mil can account for the salinity signature recorded in dolomite fluid inclusions. Distributions of fluid flux and Mg mass-balance calculations suggest that both geothermal and reflux circulation mechanisms could account for the observed distribution of dolomite in Enewetak Atoll. Furthermore, the atoll interior may be extensively dolomitized as observed in other atolls.

  6. A simple biosphere model (SiB) for use within general circulation models

    NASA Technical Reports Server (NTRS)

    Sellers, P. J.; Mintz, Y.; Sud, Y. C.; Dalcher, A.

    1986-01-01

    A simple realistic biosphere model for calculating the transfer of energy, mass and momentum between the atmosphere and the vegetated surface of the earth has been developed for use in atmospheric general circulation models. The vegetation in each terrestrial model grid is represented by an upper level, representing the perennial canopy of trees and shrubs, and a lower level, representing the annual cover of grasses and other heraceous species. The vegetation morphology and the physical and physiological properties of the vegetation layers determine such properties as: the reflection, transmission, absorption and emission of direct and diffuse radiation; the infiltration, drainage, and storage of the residual rainfall in the soil; and the control over the stomatal functioning. The model, with prescribed vegetation parameters and soil interactive soil moisture, can be used for prediction of the atmospheric circulation and precipitaion fields for short periods of up to a few weeks.

  7. A Model Study of the Salish Sea Estuarine Circulation

    DTIC Science & Technology

    2011-06-01

    Seattle, Washington NEIL S. BANAS Applied Physics Laboratory, University of Washington, Seattle, Washington LUCY F. SMEDSTAD Naval Research Laboratory...Phys. Oceanogr., 34, 1297–1312. ——, M. Kawase, and C. P. Sarason, 2007: Circulation in Carr Inlet, Puget Sound, during spring 2003. Estuaries Coasts, 6

  8. Hierarchical framework for coupling a biogeochemical trace gas model to a general circulation model

    SciTech Connect

    Miller, N.L.; Foster, I.T.

    1994-04-01

    A scheme is described for the computation of terrestrial biogeochemical trace gas fluxes in the context of a general circulation model. This hierarchical system flux scheme (HSFS) incorporates five major components: (1) a general circulation model (GCM), which provides a medium-resolution (i.e., 1{degrees} by 1{degrees}) simulation of the atmospheric circulation; (2) a procedure for identifying regions of defined homogeneity of surface type within GCM grid cells; (3) a set of surface process models, to be run within each homogeneous region, which include a biophysical model, the Biosphere Atmospheric Transfer Scheme (BATS), and a biogeochemical model (BGCM); (4) an interpolation/integration system that transfers information between the GCM and surface process models with finer resolution; and (5) an interactive data array based on a geographic information system (GIS), which provides land characteristic information via the interpolator. The goals of this detailed investigation are to compute the local and global sensitivities of trace gas fluxes to GCM and BATS variables, the effects of trace gas fluxes on global climate, and the effects of global climate on specific biomes.

  9. Venusian Polar Vortex reproduced in an Atmospheric General Circulation Model

    NASA Astrophysics Data System (ADS)

    Ando, Hiroki; Imamura, Takeshi; Takagi, Masahiro; Sugimoto, Norihiko; Kashimura, Hiroki

    The Venus atmosphere has a polar vortex rotating in the retrograde direction with a period of about three days. The vortex has a warm feature surrounded by a cold collar (e.g., Taylor et al. 1980; Piccioni et al. 2006). Although the Venusian polar vortex has been reported by many observations, its mechanism is still unknown. Elson (1982, 1989) examined the structure of the polar vortex by linear calculations. However, the background zonal wind assumed in the calculations was much stronger or weaker than those retrieved in the previous measurements (e.g., Peralta et al. 2008; Kouyama et al. 2012). Lee et al. (2010) and Yamamoto and Takahashi (2012) performed numerical simulations with general circulation models (GCMs) of the Venus atmosphere and obtained vertical structure in the polar region. However, the models included artificial forcing of Kelvin and/or Rossby waves. We have developed a new Venusian GCM by modifying the Atmospheric GCM For the Earth Simulator (Sugimoto et al. 2012; 2013). The basic equations of the GCM are primitive ones in the sigma coordinate on a sphere without topography. The model resolution is T42 (i.e., about 2.8 deg x 2.8 deg grids) and L60 (Deltaz is about 2 km). Rayleigh friction (sponge layer) in the upper layer (>80 km) is applied to prevent the reflection of waves, whose effect increases gradually with height. In the model, the atmosphere is dry and forced by the solar heating and Newtonian cooling. The vertical profile of the solar heating is based on Crisp (1986), and zonally averaged distribution is used. In addition diurnal component of the solar heating, which excites the diurnal and semi-diurnal tides, is also included. Newtonian cooling relaxes the temperature to the zonally uniform basic temperature which has a virtual static stability of Venus with almost neutral layers, and its coefficient is based on Crisp (1986). To prevent numerical instability, the biharmonic hyper-diffusion is included with 0.8 days of e-folding time

  10. Energetics of a Global Ocean Circulation Model Compared to Observations

    DTIC Science & Technology

    2011-08-09

    in the dynamics of the ocean circulation with instabilities of the strong mean currents generating eddies in the upper ocean. Interactions between...obser- vations from surface drifters, geostrophic currents from satellite altimetry, subsurface floats and deep current meter moorings. HYCOM...rings of the boundary currents [Stammer, 1997; Ferrari and Wunsch, 2009, 2010], is generated by instabilities of the mean flow and direct wind forcing

  11. Circulating DNA in diagnosis and monitoring EGFR gene mutations in advanced non-small cell lung cancer

    PubMed Central

    Del Re, Marzia; Danesi, Romano; Tiseo, Marcello

    2015-01-01

    Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are current treatments for advanced non-small cell lung cancer (NSCLC) harboring activating EGFR gene mutations. Histological or cytological samples are the standard tumor materials for EGFR mutation analysis. However, the accessibility of tumor samples is not always possible and satisfactory in advanced NSCLC patients. Moreover, totality of EGFR mutated NSCLC patients will develop resistance to EGFR-TKIs. Repeat biopsies to study genetic evolution as a result of therapy are difficult, invasive and may be confounded by intra-tumor heterogeneity. Thus, exploring accurate and less invasive techniques to (I) diagnosis EGFR mutation if tissue is not available or not appropriate for molecular analysis and to (II) monitor EGFR-TKI treatment are needed. Circulating DNA fragments carrying tumor specific sequence alterations [circulating cell-free tumor DNA (cftDNA)] are found in the cell-free fraction of blood, representing a variable and generally small fraction of the total circulating DNA. cftDNA has a high degree of specificity to detect EGFR gene mutations in NSCLC. Studies have shown the feasibility of using cftDNA to diagnosis of EGFR activating gene mutations and also to monitor tumor dynamics in NSCLC patients treated with EGFR-TKIs. These evidences suggested that non-invasive techniques based on blood samples had a great potential in EGFR mutated NSCLC patients. In this review, we summarized these non-invasive approaches and relative scientific data now available, considering their possible applications in clinical practice of NSCLC treatment. PMID:26629427

  12. Numerical modelling of the circulation of superrotating atmospheres: Venus and Titan

    NASA Technical Reports Server (NTRS)

    Hourding, F.; Talagrand, O.; Menou, K.; Fournier, R.; Dufresnes, J.-L.; Gautier, D.; Courtin, R.; Bezard, B.; McKay, C. P.

    1996-01-01

    Atmospheric superrotation is known to exist on Venus where the cloud cover, at 70 km above the surface, rotates about 60 times faster than the solid planet. Superrotation is strongly suspected on Titan on the basis of numerical studies and observations. The numerical simulation of superrotation is described. It is shown how the general circulation models, originally developed for terrestrial meteorology and climatology, can be used to infer the circulation in such atmospheres. The emphasis is on the case of Titan for which a specific general circulation model was developed.

  13. Outflow Channels Influencing Martian Climate: Global Circulation Model Simulations with Emplaced Water

    NASA Astrophysics Data System (ADS)

    Santiago, D. L.; Colaprete, A.; Haberle, R. M.; Sloan, L. C.; Asphaug, E.

    2005-03-01

    We are using the NASA Ames Mars General Circulation Model to examine the climatic consequences of the sudden burst of water from outflow channels on Mars, represented here by incrementally emplacing water on the surface.

  14. Influence of high-resolution surface databases on the modeling of local atmospheric circulation systems

    NASA Astrophysics Data System (ADS)

    Paiva, L. M. S.; Bodstein, G. C. R.; Pimentel, L. C. G.

    2014-08-01

    Large-eddy simulations are performed using the Advanced Regional Prediction System (ARPS) code at horizontal grid resolutions as fine as 300 m to assess the influence of detailed and updated surface databases on the modeling of local atmospheric circulation systems of urban areas with complex terrain. Applications to air pollution and wind energy are sought. These databases are comprised of 3 arc-sec topographic data from the Shuttle Radar Topography Mission, 10 arc-sec vegetation-type data from the European Space Agency (ESA) GlobCover project, and 30 arc-sec leaf area index and fraction of absorbed photosynthetically active radiation data from the ESA GlobCarbon project. Simulations are carried out for the metropolitan area of Rio de Janeiro using six one-way nested-grid domains that allow the choice of distinct parametric models and vertical resolutions associated to each grid. ARPS is initialized using the Global Forecasting System with 0.5°-resolution data from the National Center of Environmental Prediction, which is also used every 3 h as lateral boundary condition. Topographic shading is turned on and two soil layers are used to compute the soil temperature and moisture budgets in all runs. Results for two simulated runs covering three periods of time are compared to surface and upper-air observational data to explore the dependence of the simulations on initial and boundary conditions, grid resolution, topographic and land-use databases. Our comparisons show overall good agreement between simulated and observational data, mainly for the potential temperature and the wind speed fields, and clearly indicate that the use of high-resolution databases improves significantly our ability to predict the local atmospheric circulation.

  15. Variability of the thermohaline circulation in a simple coupled atmosphere-ocean model

    NASA Astrophysics Data System (ADS)

    Taboada, J. J.; Lorenzo, M. N.

    2003-04-01

    The behavior of the Atlantic thermohaline circulation (THC) is essential to a better understanding of climate change. Paleoclimatic studies suggest that this circulation has experimented repeated changes throughout the history of the Earth associated to climate changes [1]. The coupled 3-dimensional climate models are useful in quantitatively assessing the details of the thermohaline circulation and for comparison with observations. However, the currently available computing capacity reduces the possibility of carry out exhaustive parametric studies of the THC. Models of reduced complexity can help overcome this difficulty and make valuable contributions to a better understanding of parameter space. Moreover, these models are most useful as exploratory tools for hypothesis building. Here we study a low-order coupled atmosphere-ocean general circulation model in order to understand the behavior of the thermohaline circulation through different changes on the interaction between atmosphere-ocean [1,2]. The atmosphere is represented by a low-order atmospheric "general circulation" model introduced by Lorenz in 1984 [3] and the ocean model considered here is a 3-box model which simulates the North Atlantic thermohaline circulation [2]. [1] Broecker W.S. (1997) Thermohaline circulation, the Achilles Heel of our climate system: will man-made CO_2 upset the current balance?. Science, 278, 1582-1588. [2] Roebber, P.J. (1995) Climate variability in a low-order coupled atmosphere-ocean model. Tellus, 47A, 473-494. [3] Lorenz, E.N. (1984) Irregularity. A fundamental property of the atmosphere. Tellus, 36A, 98-110.

  16. A Wind Tunnel Model to Explore Unsteady Circulation Control for General Aviation Applications

    NASA Technical Reports Server (NTRS)

    Cagle, Christopher M.; Jones, Gregory S.

    2002-01-01

    Circulation Control airfoils have been demonstrated to provide substantial improvements in lift over conventional airfoils. The General Aviation Circular Control model is an attempt to address some of the concerns of this technique. The primary focus is to substantially reduce the amount of air mass flow by implementing unsteady flow. This paper describes a wind tunnel model that implements unsteady circulation control by pulsing internal pneumatic valves and details some preliminary results from the first test entry.

  17. Chemical Kinetic Modeling of Advanced Transportation Fuels

    SciTech Connect

    PItz, W J; Westbrook, C K; Herbinet, O

    2009-01-20

    Development of detailed chemical kinetic models for advanced petroleum-based and nonpetroleum based fuels is a difficult challenge because of the hundreds to thousands of different components in these fuels and because some of these fuels contain components that have not been considered in the past. It is important to develop detailed chemical kinetic models for these fuels since the models can be put into engine simulation codes used for optimizing engine design for maximum efficiency and minimal pollutant emissions. For example, these chemistry-enabled engine codes can be used to optimize combustion chamber shape and fuel injection timing. They also allow insight into how the composition of advanced petroleum-based and non-petroleum based fuels affect engine performance characteristics. Additionally, chemical kinetic models can be used separately to interpret important in-cylinder experimental data and gain insight into advanced engine combustion processes such as HCCI and lean burn engines. The objectives are: (1) Develop detailed chemical kinetic reaction models for components of advanced petroleum-based and non-petroleum based fuels. These fuels models include components from vegetable-oil-derived biodiesel, oil-sand derived fuel, alcohol fuels and other advanced bio-based and alternative fuels. (2) Develop detailed chemical kinetic reaction models for mixtures of non-petroleum and petroleum-based components to represent real fuels and lead to efficient reduced combustion models needed for engine modeling codes. (3) Characterize the role of fuel composition on efficiency and pollutant emissions from practical automotive engines.

  18. An advanced method for classifying atmospheric circulation types based on prototypes connectivity graph

    NASA Astrophysics Data System (ADS)

    Zagouras, Athanassios; Argiriou, Athanassios A.; Flocas, Helena A.; Economou, George; Fotopoulos, Spiros

    2012-11-01

    Classification of weather maps at various isobaric levels as a methodological tool is used in several problems related to meteorology, climatology, atmospheric pollution and to other fields for many years. Initially the classification was performed manually. The criteria used by the person performing the classification are features of isobars or isopleths of geopotential height, depending on the type of maps to be classified. Although manual classifications integrate the perceptual experience and other unquantifiable qualities of the meteorology specialists involved, these are typically subjective and time consuming. Furthermore, during the last years different approaches of automated methods for atmospheric circulation classification have been proposed, which present automated and so-called objective classifications. In this paper a new method of atmospheric circulation classification of isobaric maps is presented. The method is based on graph theory. It starts with an intelligent prototype selection using an over-partitioning mode of fuzzy c-means (FCM) algorithm, proceeds to a graph formulation for the entire dataset and produces the clusters based on the contemporary dominant sets clustering method. Graph theory is a novel mathematical approach, allowing a more efficient representation of spatially correlated data, compared to the classical Euclidian space representation approaches, used in conventional classification methods. The method has been applied to the classification of 850 hPa atmospheric circulation over the Eastern Mediterranean. The evaluation of the automated methods is performed by statistical indexes; results indicate that the classification is adequately comparable with other state-of-the-art automated map classification methods, for a variable number of clusters.

  19. Use of weather types to disaggregate general circulation model predictions

    USGS Publications Warehouse

    Hay, L.E.; McCabe, G.J.; Wolock, D.M.; Ayers, M.A.

    1992-01-01

    A method has been developed that uses weather-type analysis as a tool to spatially disaggregate GCM predictions to make them useful for water resource studies. The method has been applied to the Delaware River basin to predict the effects of doubling atmospheric carbon dioxide on precipitation patterns in the region. An application of the technique to the Delaware River basin indicates that future climate conditions will show minimal changes in weather-type frequency, implying that air circulation patterns will remain unchanged -from Authors

  20. Coastal Modeling System Advanced Topics

    DTIC Science & Technology

    2012-06-18

    is the CMS? Integrated wave, current, and morphology change model in the Surface-water Modeling System (SMS). Why CMS? Operational at 10...Coupled with spectral wave model (CMS-Wave)  Wave-current interactions  Inline sediment transport and morphology change  Non-equilibrium...Easy to setup  Telescoping grid: Efficient and flexible  Solver options  Implicit: Tidal flow, long-term morphology change. ~10 min

  1. Modeling of Spacecraft Advanced Chemical Propulsion Systems

    NASA Technical Reports Server (NTRS)

    Benfield, Michael P. J.; Belcher, Jeremy A.

    2004-01-01

    This paper outlines the development of the Advanced Chemical Propulsion System (ACPS) model for Earth and Space Storable propellants. This model was developed by the System Technology Operation of SAIC-Huntsville for the NASA MSFC In-Space Propulsion Project Office. Each subsystem of the model is described. Selected model results will also be shown to demonstrate the model's ability to evaluate technology changes in chemical propulsion systems.

  2. Exploring the Impact of Students' Learning Approach on Collaborative Group Modeling of Blood Circulation

    ERIC Educational Resources Information Center

    Lee, Shinyoung; Kang, Eunhee; Kim, Heui-Baik

    2015-01-01

    This study aimed to explore the effect on group dynamics of statements associated with deep learning approaches (DLA) and their contribution to cognitive collaboration and model development during group modeling of blood circulation. A group was selected for an in-depth analysis of collaborative group modeling. This group constructed a model in a…

  3. Interpretation of cloud-climate feedback as produced by 14 atmospheric general circulation models

    NASA Technical Reports Server (NTRS)

    Cess, R. D.; Potter, G. L.; Ghan, S. J.; Blanchet, J. P.; Boer, G. J.

    1989-01-01

    Understanding the cause of differences among general circulation model projections of carbon dioxide-induced climatic change is a necessary step toward improving the models. An intercomparison of 14 atmospheric general circulation models, for which sea surface temperature perturbations were used as a surrogate climate change, showed that there was a roughly threefold variation in global climate sensitivity. Most of this variation is attributable to differences in the models' depictions of cloud-climate feedback, a result that emphasizes the need for improvements in the treatment of clouds in these models if they are ultimately to be used as climatic predictors.

  4. Numerical Model Studies of the Martian Mesoscale Circulations

    NASA Technical Reports Server (NTRS)

    Segal, M.; Arritt, R. W.

    1996-01-01

    Studies concerning mesoscale topographical effects on Martian flows examined low-level jets in the near equatorial latitudes and the dynamical intensification of flow by steep terrain. Continuation of work from previous years included evaluating the dissipation of cold air mass outbreaks due to enhanced sensible heat flux, further sensitivity and scaling evaluations for generalization of the characteristics of Martian mesoscale circulation caused by horizontal sensible heat-flux gradients, and evaluations of the significance that non-uniform surface would have on enhancing the polar CO2 ice sublimation during the spring. The sensitivity of maximum and minimum atmospheric temperatures to changes in wind speed, surface albedo, and deep soil temperature was investigated.

  5. Model Standards Advance the Profession

    ERIC Educational Resources Information Center

    Journal of Staff Development, 2011

    2011-01-01

    Leadership by teachers is essential to serving the needs of students, schools, and the teaching profession. To that end, the Teacher Leadership Exploratory Consortium has developed Teacher Leader Model Standards to codify, promote, and support teacher leadership as a vehicle to transform schools for the needs of the 21st century. The Teacher…

  6. Successful surgical repair of an infectious thoracic aortic pseudoaneurysm accompanied by aortobronchopulmonary fistula and advanced hepatic dysfunction without assisted circulation.

    PubMed

    Masuhara, Hiroshi; Watanabe, Yoshinori; Fujii, Takeshiro; Shiono, Noritsugu; Hamada, Satoshi; Hara, Masanori; Teramoto, Chikao; Yoshihara, Katsunori; Koyama, Nobuya

    2010-08-01

    The patient was a 59-year-old female. Because of massive hemoptysis, she was brought to our emergency center by ambulance. Thoracic computed tomography led to a diagnosis of an infectious thoracic aortic pseudoaneurysm accompanied by an aortobronchopulmonary fistula. Emergency surgery followed. Also noted was an advanced hepatic dysfunction, assessed as Child-Pugh score B, caused by an alcoholic liver disease. A localized affected area made it possible for us to perform an aneurysmectomy using a temporary bypass rather than assisted circulation. A patch plasty using expanded polytetrafluoroethylene completed the procedure. Streptococcus agalactiae (GBS) was detected in a sample obtained during the surgery from an abscess located in the aneurysm. The patient made satisfactory postoperative progress and left the hospital walking unaided on the 36th postoperative day.

  7. Advanced Space Shuttle simulation model

    NASA Technical Reports Server (NTRS)

    Tatom, F. B.; Smith, S. R.

    1982-01-01

    A non-recursive model (based on von Karman spectra) for atmospheric turbulence along the flight path of the shuttle orbiter was developed. It provides for simulation of instantaneous vertical and horizontal gusts at the vehicle center-of-gravity, and also for simulation of instantaneous gusts gradients. Based on this model the time series for both gusts and gust gradients were generated and stored on a series of magnetic tapes, entitled Shuttle Simulation Turbulence Tapes (SSTT). The time series are designed to represent atmospheric turbulence from ground level to an altitude of 120,000 meters. A description of the turbulence generation procedure is provided. The results of validating the simulated turbulence are described. Conclusions and recommendations are presented. One-dimensional von Karman spectra are tabulated, while a discussion of the minimum frequency simulated is provided. The results of spectral and statistical analyses of the SSTT are presented.

  8. The application of Seasat-1 radar altimetry to continental shelf circulation modeling

    NASA Technical Reports Server (NTRS)

    Cornillon, P.; Reed, M.; Spaulding, M.; Swanson, C.

    1980-01-01

    Seasat-1 radar altimetry data have been used to verify a continental shelf circulation model subjected to tidal forcing on the open boundary. The model makes use of the semi-implicit mode of time integration, removing the surface gravity wave time step restriction. Both the altimetry and the model predictions are compared with empirically determined tidal fluctuations and generally good agreement is obtained.

  9. Modeling Advance Life Support Systems

    NASA Technical Reports Server (NTRS)

    Pitts, Marvin; Sager, John; Loader, Coleen; Drysdale, Alan

    1996-01-01

    Activities this summer consisted of two projects that involved computer simulation of bioregenerative life support systems for space habitats. Students in the Space Life Science Training Program (SLSTP) used the simulation, space station, to learn about relationships between humans, fish, plants, and microorganisms in a closed environment. One student complete a six week project to modify the simulation by converting the microbes from anaerobic to aerobic, and then balancing the simulation's life support system. A detailed computer simulation of a closed lunar station using bioregenerative life support was attempted, but there was not enough known about system restraints and constants in plant growth, bioreactor design for space habitats and food preparation to develop an integrated model with any confidence. Instead of a completed detailed model with broad assumptions concerning the unknown system parameters, a framework for an integrated model was outlined and work begun on plant and bioreactor simulations. The NASA sponsors and the summer Fell were satisfied with the progress made during the 10 weeks, and we have planned future cooperative work.

  10. Micromechanical modeling of advanced materials

    SciTech Connect

    Silling, S.A.; Taylor, P.A.; Wise, J.L.; Furnish, M.D.

    1994-04-01

    Funded as a laboratory-directed research and development (LDRD) project, the work reported here focuses on the development of a computational methodology to determine the dynamic response of heterogeneous solids on the basis of their composition and microstructural morphology. Using the solid dynamics wavecode CTH, material response is simulated on a scale sufficiently fine to explicitly represent the material`s microstructure. Conducting {open_quotes}numerical experiments{close_quotes} on this scale, the authors explore the influence that the microstructure exerts on the material`s overall response. These results are used in the development of constitutive models that take into account the effects of microstructure without explicit representation of its features. Applying this methodology to a glass-reinforced plastic (GRP) composite, the authors examined the influence of various aspects of the composite`s microstructure on its response in a loading regime typical of impact and penetration. As a prerequisite to the microscale modeling effort, they conducted extensive materials testing on the constituents, S-2 glass and epoxy resin (UF-3283), obtaining the first Hugoniot and spall data for these materials. The results of this work are used in the development of constitutive models for GRP materials in transient-dynamics computer wavecodes.

  11. Left ventricular finite element model bounded by a systemic circulation model.

    PubMed

    Veress, A I; Raymond, G M; Gullberg, G T; Bassingthwaighte, J B

    2013-05-01

    A series of models were developed in which a circulatory system model was coupled to an existing series of finite element (FE) models of the left ventricle (LV). The circulatory models were used to provide realistic boundary conditions for the LV models. This was developed for the JSim analysis package and was composed of a systemic arterial, capillary, and venous system in a closed loop with a varying elastance LV and left atria to provide the driving pressures and flows matching those of the FE model. Three coupled models were developed, a normal LV under normotensive aortic loading (116/80 mm Hg), a mild hypertension (137/89 mm Hg) model, and a moderate hypertension model (165/100 mm Hg). The initial step in the modeling analysis was that the circulation was optimized to the end-diastolic pressure and volume values of the LV model. The cardiac FE models were then optimized to the systolic pressure/volume characteristics of the steady-state JSim circulatory model solution. Comparison of the stress predictions for the three models indicated that the mild hypertensive case produced a 21% increase in the average fiber stress levels, and the moderate hypertension case had a 36% increase in average stress. The circulatory work increased by 18% and 43% over that of the control for the mild and moderate hypertensive cases, respectively.

  12. Evaluation of a Mineral Dust Simulation in the Atmospheric-Chemistry General Circulation Model-EMAC

    NASA Astrophysics Data System (ADS)

    Abdel Kader, M.; Astitha, M.; Lelieveld, J.

    2012-04-01

    This study presents an evaluation of the atmospheric mineral dust cycle in the Atmospheric Chemistry General Circulation Model (AC-GCM) using new developed dust emissions scheme. The dust cycle, as an integral part of the Earth System, plays an important role in the Earth's energy balance by both direct and indirect ways. As an aerosol, it significantly impacts the absorption and scattering of radiation in the atmosphere and can modify the optical properties of clouds and snow/ice surfaces. In addition, dust contributes to a range of physical, chemical and bio-geological processes that interact with the cycles of carbon and water. While our knowledge of the dust cycle, its impacts and interactions with the other global-scale bio-geochemical cycles has greatly advanced in the last decades, large uncertainties and knowledge gaps still exist. Improving the dust simulation in global models is essential to minimize the uncertainties in the model results related to dust. In this study, the results are based on the ECHAM5 Modular Earth Submodel System (MESSy) AC-GCM simulations using T106L31 spectral resolution (about 120km ) with 31 vertical levels. The GMXe aerosol submodel is used to simulate the phase changes of the dust particles between soluble and insoluble modes. Dust emission, transport and deposition (wet and dry) are calculated on-line along with the meteorological parameters in every model time step. The preliminary evaluation of the dust concentration and deposition are presented based on ground observations from various campaigns as well as the evaluation of the optical properties of dust using AERONET and satellite (MODIS and MISR) observations. Preliminarily results show good agreement with observations for dust deposition and optical properties. In addition, the global dust emissions, load, deposition and lifetime is in good agreement with the published results. Also, the uncertainties in the dust cycle that contribute to the overall model performance

  13. Evaluating the deep-ocean circulation of a global ocean model using carbon isotopic ratios

    NASA Astrophysics Data System (ADS)

    Paul, André; Dutkiewicz, Stephanie; Gebbie, Jake; Losch, Martin; Marchal, Olivier

    2016-04-01

    We study the sensitivity of a global three-dimensional biotic ocean carbon-cycle model to the parameterizations of gas exchange and biological productivity as well as to deep-ocean circulation strength, and we employ the carbon isotopic ratios δ13C and Δ14C of dissolved inorganic carbon for a systematic evaluation against observations. Radiocarbon (Δ14C) in particular offers the means to assess the model skill on a time scale of 100 to 1000 years relevant to the deep-ocean circulation. The carbon isotope ratios are included as tracers in the MIT general circulation model (MITgcm). The implementation involves the fractionation processes during photosynthesis and air-sea gas exchange. We present the results of sixteen simulations combining two different parameterizations of the piston velocity, two different parameterizations of biological productivity (including the effect of iron fertilization) and four different overturning rates. These simulations were first spun up to equilibrium (more than 10,000 years of model simulation) and then continued from AD 1765 to AD 2002. For the model evaluation, we followed the OCMIP-2 (Ocean Carbon-Cycle Model Intercomparision Project phase two) protocol, comparing the results to GEOSECS (Geochemical Ocean Sections Survey) and WOCE (World Ocean Circulation Experiment) δ13C and natural Δ14C data in the world ocean. The range of deep natural Δ14C (below 1000 m) for our single model (MITgcm) was smaller than for the group of different OCMIP-2 models. Furthermore, differences between different model parameterizations were smaller than for different overturning rates. We conclude that carbon isotope ratios are a useful tool to evaluate the deep-ocean circulation. Since they are also available from deep-sea sediment records, we postulate that the simulation of carbon isotope ratios in a global ocean model will aid in estimating the deep-ocean circulation and climate during present and past.

  14. Mars Global Surveyor: Aerobraking and Observations Support Using a Mars Global Circulation Model

    NASA Technical Reports Server (NTRS)

    Hollingsworth, Jeffery L.; Bridger, Alison F. C.; Haberle, Robert M.

    1997-01-01

    This is a Final Report for a Joint Research Interchange (JRI) between NASA Ames Research Center and San Jose State University, Department of Meteorology. Using a global atmospheric circulation model for Mars, the focus of this JRI has been to provide support for the Mars Global Surveyor (MGS) spacecraft aerobraking activities and interpretation guidance of preliminary observations. The primary atmospheric model applied in this investigation has been a high-top version of the NASA Ames Mars general circulation model (MGCM). Comparisons with an atmospheric model designed primarily for engineering purposes (Mars-GRAM) has also been carried out. From a suite of MGCM simulations, we have assessed plausible spatial and temporal variability in atmospheric density at high altitudes (e.g., 70-1 10 km) for seasonal dates and locations during Phase 1 aerobraking. Diagnostic tools have been developed to analyze circulation fields from the MGCM simulations, and these tools have been applied in the creation of a Mars climate catalogue database. Throughout Phase I aerobraking activities, analysis products have been provided to the MGS aerobraking atmospheric advisory group (AAG). Analyses of circulation variability at the coupling level between the MGCM and a Mars thermospheric global circulation model (MTGCM) has also been assessed. Finally, using a quasi-geostrophic dynamical formulation with the MGCM simulations, diagnosis of breaking planetary (Rossby) waves in Mars middle atmosphere has been carried out. Titles of papers presented at scientific workshops and seminars, and a publication in the scientific literature are provided.

  15. Mars Global Surveyor: Aerobraking and Observations Support Using a Mars Global Circulation Model

    NASA Technical Reports Server (NTRS)

    Hollingsworth, Jeffery L.; Bridger, Alison F. C.; Harberle, Robert M.

    1997-01-01

    This is a Final Report for a Joint Research Interchange (JRI) between NASA Ames Research Center and San Jose State University, Department of Meteorology. Using a global atmospheric circulation model for Mars, the focus of this JRI has been to provide support for the Mars Global Surveyor (MGS) spacecraft aerobraking activities and interpretation guidance of preliminary observations. ne primary atmospheric model applied in this investigation has been a high-top version of the NASA Ames Mars general circulation model (MGCM). Comparisons with an atmospheric model designed primarily for engineering purposes (Mars-GRAM) has also been carried out. From a suite of MGCM simulations, we have assessed plausible spatial and temporal variability in atmospheric density at high altitudes (e.g., 70-110 km) for seasonal dates and locations during Phase 1 aerobraking. Diagnostic tools have been developed to analyze circulation fields from the MGCM simulations, and these tools have been applied in the creation of a Mars climate catalogue database. Throughout Phase 1 aerobraking activities, analysis products have been provided to the MGS aerobraking atmospheric advisory group (AAG). Analyses of circulation variability at the coupling level between the MGCM and a Mars thermospheric global circulation model (MTGCM) has also been assessed. Finally, using a quasi-geostrophic dynamical formulation with the MGCM simulations, diagnosis of breaking planetary (Rossby) waves in Mars' middle atmosphere has been carried out. Titles of papers presented at scientific workshops and seminars, and a publication in the scientific literature are provided.

  16. An Intercomparison of the Dynamical Cores of Global Atmospheric Circulation Models for Mars

    NASA Technical Reports Server (NTRS)

    Hollingsworth, Jeffery L.; Bridger, Alison F. C.; Haberle, Robert M.

    1998-01-01

    This is a Final Report for a Joint Research Interchange (JRI) between NASA Ames Research Center and San Jose State University, Department of Meteorology. The focus of this JRI has been to evaluate the dynamical 'cores' of two global atmospheric circulation models for Mars that are in operation at the NASA Ames Research Center. The two global circulation models in use are fundamentally different: one uses spherical harmonics in its horizontal representation of field variables; the other uses finite differences on a uniform longitude-latitude grid. Several simulations have been conducted to assess how the dynamical processors of each of these circulation models perform using identical 'simple physics' parameterizations. A variety of climate statistics (e.g., time-mean flows and eddy fields) have been compared for realistic solstitial mean basic states. Results of this research have demonstrated that the two Mars circulation models with completely different spatial representations and discretizations produce rather similar circulation statistics for first-order meteorological fields, suggestive of a tendency for convergence of numerical solutions. Second and higher-order fields can, however, vary significantly between the two models.

  17. Mars Global Surveyor: Aerobraking and Observations Support Using a Mars Global Circulation Model

    NASA Technical Reports Server (NTRS)

    Hollingsworth, Jeffery L.; Bridger, Alison F. C.; Haberle, Robert M.

    1997-01-01

    This is a Final Report for a Joint Research Interchange (JRI) between NASA Ames Research Center and San Jose State University, Department of Meteorology. Using a global atmospheric circulation model for Mars, the focus of this JRI has been to provide support for the Mars Global Surveyor (MGS) spacecraft aerobraking activities and interpretation guidance of preliminary observations. The primary atmospheric model applied in this investigation has been a high-top version of the NASA Ames Mars general circulation model (MGCM). Comparisons with an atmospheric model designed primarily for engineering purposes (Mars-GRAM) has also been carried out. From a suite of MGCM simulations, we have assessed plausible spatial and temporal variability in atmospheric density at high altitudes (e.g., 70-110 km) for seasonal dates and locations during Phase I aerobraking. Diagnostic tools have been developed to analyze circulation fields from the MGCM simulations, and these tools have been applied in the creation of a Mars climate catalogue database. Throughout Phase I aerobraking activities, analysis products have been provided to the MGS aerobraking atmospheric advisory group (AAG). Analyses of circulation variability at the coupling level between the MGCM and a Mars thermospheric global circulation model (MTGCM) has also been assessed. Finally, using a quasi-geostrophic dynamical formulation with the MGCM simulations, diagnosis of breaking planetary (Rossby) waves in Mars' middle atmosphere has been carried out. Titles of papers presented at scientific workshops and seminars, and a publication in the scientific literature are provided.

  18. A long term model of circulation. [human body

    NASA Technical Reports Server (NTRS)

    White, R. J.

    1974-01-01

    A quantitative approach to modeling human physiological function, with a view toward ultimate application to long duration space flight experiments, was undertaken. Data was obtained on the effect of weightlessness on certain aspects of human physiological function during 1-3 month periods. Modifications in the Guyton model are reviewed. Design considerations for bilateral interface models are discussed. Construction of a functioning whole body model was studied, as well as the testing of the model versus available data.

  19. The influence of the tropics upon the prediction of the Southern Hemisphere circulation within the GLAS GCM. [Goddard Laboratory for Atmospheric Sciences General Circulation Model

    NASA Technical Reports Server (NTRS)

    Baker, W. E.; Paegle, J.

    1983-01-01

    An examination is undertaken of the sensitivity of short term Southern Hemisphere circulation prediction to tropical wind data and tropical latent heat release. The data assimilation experiments employ the Goddard Laboratory for Atmospheric Sciences' fourth-order general circulation model. Two of the experiments are identical, but for the fact that one uses tropical wind data while the other does not. A third experiment contains the identical initial conditions of forecasts with tropical winds, while suppressing tropical latent heat release.

  20. Regional climates in the GISS general circulation model: Surface air temperature

    NASA Technical Reports Server (NTRS)

    Hewitson, Bruce

    1994-01-01

    One of the more viable research techniques into global climate change for the purpose of understanding the consequent environmental impacts is based on the use of general circulation models (GCMs). However, GCMs are currently unable to reliably predict the regional climate change resulting from global warming, and it is at the regional scale that predictions are required for understanding human and environmental responses. Regional climates in the extratropics are in large part governed by the synoptic-scale circulation and the feasibility of using this interscale relationship is explored to provide a way of moving to grid cell and sub-grid cell scales in the model. The relationships between the daily circulation systems and surface air temperature for points across the continental United States are first developed in a quantitative form using a multivariate index based on principal components analysis (PCA) of the surface circulation. These relationships are then validated by predicting daily temperature using observed circulation and comparing the predicted values with the observed temperatures. The relationships predict surface temperature accurately over the major portion of the country in winter, and for half the country in summer. These relationships are then applied to the surface synoptic circulation of the Goddard Institute for Space Studies (GISS) GCM control run, and a set of surface grid cell temperatures are generated. These temperatures, based on the larger-scale validated circulation, may now be used with greater confidence at the regional scale. The generated temperatures are compared to those of the model and show that the model has regional errors of up to 10 C in individual grid cells.

  1. Recent advances in modeling stellar interiors (u)

    SciTech Connect

    Guzik, Joyce Ann

    2010-01-01

    Advances in stellar interior modeling are being driven by new data from large-scale surveys and high-precision photometric and spectroscopic observations. Here we focus on single stars in normal evolutionary phases; we will not discuss the many advances in modeling star formation, interacting binaries, supernovae, or neutron stars. We review briefly: (1) updates to input physics of stellar models; (2) progress in two and three-dimensional evolution and hydrodynamic models; (3) insights from oscillation data used to infer stellar interior structure and validate model predictions (asteroseismology). We close by highlighting a few outstanding problems, e.g., the driving mechanisms for hybrid {gamma} Dor/{delta} Sct star pulsations, the cause of giant eruptions seen in luminous blue variables such as {eta} Car and P Cyg, and the solar abundance problem.

  2. Recent advances in modeling stellar interiors

    NASA Astrophysics Data System (ADS)

    Guzik, Joyce Ann

    2011-11-01

    Advances in stellar interior modeling are being driven by new data from large-scale surveys and high-precision photometric and spectroscopic observations. Here we focus on single stars in normal evolutionary phases; we will not discuss the many advances in modeling star formation, interacting binaries, supernovae, or neutron stars. We review briefly: (1) updates to input physics of stellar models; (2) progress in two and three-dimensional evolution and hydrodynamic models; (3) insights from oscillation data used to infer stellar interior structure and validate model predictions (asteroseismology). We close by highlighting a few outstanding problems, e.g., the driving mechanisms for hybrid γ Dor/ δ Sct star pulsations, the cause of giant eruptions seen in luminous blue variables such as η Car and P Cyg, and the solar abundance problem.

  3. Optimization of a Parallel Ocean General Circulation Model

    NASA Technical Reports Server (NTRS)

    Chao, Yi

    1997-01-01

    Global climate modeling is one of the grand chalenges of computational science, and ocean modeling plays an important role in both understanding the current climatic conditions and predicting the future climate change.

  4. Advances in Scientific Balloon Thermal Modeling

    NASA Technical Reports Server (NTRS)

    Bohaboj, T.; Cathey, H. M., Jr.

    2004-01-01

    The National Aeronautics and Space Administration's Balloon Program office has long acknowledged that the accurate modeling of balloon performance and flight prediction is dependant on how well the balloon is thermally modeled. This ongoing effort is focused on developing accurate balloon thermal models that can be used to quickly predict balloon temperatures and balloon performance. The ability to model parametric changes is also a driver for this effort. This paper will present the most recent advances made in this area. This research effort continues to utilize the "Thrmal Desktop" addition to AUTO CAD for the modeling. Recent advances have been made by using this analytical tool. A number of analyses have been completed to test the applicability of this tool to the problem with very positive results. Progressively detailed models have been developed to explore the capabilities of the tool as well as to provide guidance in model formulation. A number of parametric studies have been completed. These studies have varied the shape of the structure, material properties, environmental inputs, and model geometry. These studies have concentrated on spherical "proxy models" for the initial development stages and then to transition to the natural shaped zero pressure and super pressure balloons. An assessment of required model resolution has also been determined. Model solutions have been cross checked with known solutions via hand calculations. The comparison of these cases will also be presented. One goal is to develop analysis guidelines and an approach for modeling balloons for both simple first order estimates and detailed full models. This papa presents the step by step advances made as part of this effort, capabilities, limitations, and the lessons learned. Also presented are the plans for further thermal modeling work.

  5. Documentation of the GLAS fourth order general circulation model. Volume 2: Scalar code

    NASA Technical Reports Server (NTRS)

    Kalnay, E.; Balgovind, R.; Chao, W.; Edelmann, D.; Pfaendtner, J.; Takacs, L.; Takano, K.

    1983-01-01

    Volume 2, of a 3 volume technical memoranda contains a detailed documentation of the GLAS fourth order general circulation model. Volume 2 contains the CYBER 205 scalar and vector codes of the model, list of variables, and cross references. A variable name dictionary for the scalar code, and code listings are outlined.

  6. A MODEL FOR FINE PARTICLE AGGLOMERATION IN CIRCULATING FLUIDIZED BED ABSORBERS

    EPA Science Inventory

    A model for fine particle agglomeration in circulating fluidized bed absorbers (CFBAS) has been developed. It can model the influence of different factors on agglomeration, such as the geometry of CFBAs, superficial gas velocity, initial particle size distribution, and type of ag...

  7. A small parameter model of circulation in a homogeoneous baroclinic ocean

    NASA Technical Reports Server (NTRS)

    Borisenkov, Y. P.

    1974-01-01

    A small parameter model of circulation in a homogeneous baroclinic ocean is presented. The principles common to the construction of small parameter models and certain energetic principles developed in connection with atmospheric processes are made use of. These principles were applied in the study of processes in a baroclinic ocean.

  8. Uncertainties in Carbon Dioxide Radiative Forcing in Atmospheric General Circulation Models

    NASA Technical Reports Server (NTRS)

    Cess, R. D.; Zhang, M.-H.; Potter, G. L.; Gates, W. L.; Taylor, K. E.; Barker, H. W.; Colman, R. A.; Fraser, J. R.; McAvaney, B. J.; Dazlich, D. A.; Randall, D. A.; DelGenio, A. D.; Lacis, A. A.; Esch, M.; Roeckner, E.; Galin, V.; Hack, J. J.; Kiehl, J. T.; Ingram, W. J.; LeTreut, H.

    1993-01-01

    Global warming, caused by an increase in the concentrations of greenhouse gases, is the direct result of greenhouse gas-induced radiative forcing. When a doubling of atmospheric carbon dioxide is considered, this forcing differed substantially among 15 atmospheric general circulation models. Although there are several potential causes, the largest contributor was the carbon dioxide radiation parameterizations of the models.

  9. A new model to simulate the Martian mesoscale and microscale atmospheric circulation: Validation and first results

    NASA Astrophysics Data System (ADS)

    Spiga, Aymeric; Forget, François

    2009-02-01

    The Laboratoire de Météorologie Dynamique (LMD) Mesoscale Model is a new versatile simulator of the Martian atmosphere and environment at horizontal scales ranging from hundreds of kilometers to tens of meters. The model combines the National Centers for Environmental Prediction(NCEP)-National Center for Atmospheric Research (NCAR) fully compressible nonhydrostatic Advanced Research Weather Research and Forecasting (ARW-WRF) dynamical core, adapted to Mars, with the LMD-general circulation model (GCM) comprehensive set of physical parameterizations for the Martian dust, CO2, water, and photochemistry cycles. Since LMD-GCM large-scale simulations are also used to drive the mesoscale model at the boundaries of the chosen domain of interest, a high level of downscaling consistency is reached. To define the initial state and the atmosphere at the domain boundaries, a specific ``hybrid'' vertical interpolation from the coarse-resolution GCM fields to the high-resolution mesoscale domain is used to ensure the stability and the physical relevancy of the simulations. Used in synoptic-scale mode with a cyclic domain wrapped around the planet, the mesoscale model correctly replicates the main large-scale thermal structure and the zonally propagating waves. The model diagnostics of the near-surface pressure, wind, and temperature daily cycles in Chryse Planitia are in accordance with the Viking and Pathfinder measurements. Afternoon gustiness at the respective landing sites is adequately accounted for on the condition that convective adjustment is turned off in the mesoscale simulations. On the rims of Valles Marineris, intense daytime anabatic (~30 m s-1) and nighttime katabatic (~40 m s-1) winds are predicted. Within the canyon corridors, topographical channeling can amplify the wind a few kilometers above the ground, especially during the night. Through large-eddy simulations in Gusev Crater, the model describes the mixing layer growth during the afternoon, and the

  10. Investigating the circulation patterns of the northern Adriatic Sea with a very high resolution model.

    NASA Astrophysics Data System (ADS)

    Zavatarelli, M.; Mattia, G.; Lovato, T.

    2015-12-01

    The NEMO model was implemented on the northern Adriatic sea with an high resolution (horizontal resolution of 800 m and vertical resolution of 2 m). The model is off-line nested with a general circulation model of Mediterranean sea providing open boundary data. Hindcast simulations with high frequency atmospheric forcing and daily river runoff, were performed and analyzed in order to study the interannual variability of the circulation pattern and of the shelf dense water (Northern Adriatic dense Water, NADW) production in relation to the freshwater input and heat and wind forcing. Whenever possible, the results were validated against available observations. The simulations highlighted the large interannual variability of the circulation patterns. This is a contribution of the EU-FP7 Project "PERSEUS" (Policy oriented environmental research in the Southern European Seas)

  11. Center for Advanced Modeling and Simulation Intern

    SciTech Connect

    Gertman, Vanessa

    2010-01-01

    Some interns just copy papers and seal envelopes. Not at INL! Check out how Vanessa Gertman, an INL intern working at the Center for Advanced Modeling and Simulation, spent her summer working with some intense visualization software. Lots more content like this is available at INL's facebook page http://www.facebook.com/idahonationallaboratory.

  12. Center for Advanced Modeling and Simulation Intern

    ScienceCinema

    Gertman, Vanessa

    2016-07-12

    Some interns just copy papers and seal envelopes. Not at INL! Check out how Vanessa Gertman, an INL intern working at the Center for Advanced Modeling and Simulation, spent her summer working with some intense visualization software. Lots more content like this is available at INL's facebook page http://www.facebook.com/idahonationallaboratory.

  13. A vertically averaged spectral model for tidal circulation in estuaries

    USGS Publications Warehouse

    Burau, J.R.; Cheng, R.T.

    1989-01-01

    A frequency dependent computer model based on the two-dimensional vertically averaged shallow-water equations is described for general purpose application in tidally dominated embayments. This model simulates the response of both tides and tidal currents to user-specified geometries and boundary conditions. The mathematical formulation and practical application of the model are discussed in detail. Salient features of the model include the ability to specify: (1) stage at the open boundaries as well as within the model grid, (2) velocities on open boundaries (river inflows and so forth), (3) spatially variable wind stress, and (4) spatially variable bottom friction. Using harmonically analyzed field data as boundary conditions, this model can be used to make real time predictions of tides and tidal currents. (USGS)

  14. COBRA-WC model and predictions for a fast-reactor natural-circulation transient. [LMFBR

    SciTech Connect

    George, T.L.; Basehore, K.L.; Prather, W.A.

    1980-01-01

    The COBRA-WC (Whole Core) code has been used to predict the core-wide coolant and rod temperature distribution in a liquid metal fast reactor during the early part (first 220 seconds) of a natural circulation transient. Approximately one-sixth of the core was modeled including bypass flows and the pressure losses above and below the core region. Detailed temperature and flow distributions were obtained for the two test fuel assemblies. The COBRA-WC model, the approach, and predictions of core-wide transient coolant and rod temperatures during a natural circulation transient are presented in this paper.

  15. A Hydrodynamic Model of The Human Leg Circulation.

    ERIC Educational Resources Information Center

    Klabunde, Richard E.; McDowell, Donald E.

    1984-01-01

    Describes the construction and use of a life-size model which shows blood flow under normal and pathological conditions. Four experimental procedures (single vessel occlusion, dilation of distal vascular bed, single artery stenosis, and multiple artery stenoses) typical of those demonstrated by the model are discussed and diagrammed. (DH)

  16. Observations and Modeling of the West Florida Continental Shelf Circulation

    DTIC Science & Technology

    2001-09-30

    Weisberg (2001b) provide a detailed comparison between modeled and observed sea level and velocity hodograph ellipses for the M2, S2. K1, and O1...constituents, and on the basis of this provide the co- amplitude, co-range, and hodograph maps for the model region. We also discuss Lagrangian trajectories

  17. Recent results from the GISS model of the global atmosphere. [circulation simulation for weather forecasting

    NASA Technical Reports Server (NTRS)

    Somerville, R. C. J.

    1975-01-01

    Large numerical atmospheric circulation models are in increasingly widespread use both for operational weather forecasting and for meteorological research. The results presented here are from a model developed at the Goddard Institute for Space Studies (GISS) and described in detail by Somerville et al. (1974). This model is representative of a class of models, recently surveyed by the Global Atmospheric Research Program (1974), designed to simulate the time-dependent, three-dimensional, large-scale dynamics of the earth's atmosphere.

  18. Computational ocean acoustics: Advances in 3D ocean acoustic modeling

    NASA Astrophysics Data System (ADS)

    Schmidt, Henrik; Jensen, Finn B.

    2012-11-01

    The numerical model of ocean acoustic propagation developed in the 1980's are still in widespread use today, and the field of computational ocean acoustics is often considered a mature field. However, the explosive increase in computational power available to the community has created opportunities for modeling phenomena that earlier were beyond reach. Most notably, three-dimensional propagation and scattering problems have been prohibitive computationally, but are now addressed routinely using brute force numerical approaches such as the Finite Element Method, in particular for target scattering problems, where they are being combined with the traditional wave theory propagation models in hybrid modeling frameworks. Also, recent years has seen the development of hybrid approaches coupling oceanographic circulation models with acoustic propagation models, enabling the forecasting of sonar performance uncertainty in dynamic ocean environments. These and other advances made over the last couple of decades support the notion that the field of computational ocean acoustics is far from being mature. [Work supported by the Office of Naval Research, Code 321OA].

  19. A Simplified Teaching Model of the Heart and Circulation

    ERIC Educational Resources Information Center

    Rodbard, Simon; And Others

    1976-01-01

    Diagrams and explains the construction of a model for the heart and its valves and function of the atria and ventricles, using the contraction of a student's hand to simulate heart contraction. Approximate cost $125. (CS)

  20. Prediction of cloud droplet number in a general circulation model

    SciTech Connect

    Ghan, S.J.; Leung, L.R.

    1996-04-01

    We have applied the Colorado State University Regional Atmospheric Modeling System (RAMS) bulk cloud microphysics parameterization to the treatment of stratiform clouds in the National Center for Atmospheric Research Community Climate Model (CCM2). The RAMS predicts mass concentrations of cloud water, cloud ice, rain and snow, and number concnetration of ice. We have introduced the droplet number conservation equation to predict droplet number and it`s dependence on aerosols.

  1. Global coupled ocean-atmosphere general circulation models in LASG/IAP

    NASA Astrophysics Data System (ADS)

    Yongqiang, Yu; Xuehong, Zhang; Yufu, Guo

    2004-06-01

    Coupled ocean-atmospheric general circulation models are the only tools to quantitatively simulate the climate system. Since the end of the 1980s, a group of scientists in the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics (IAP), Chinese Academy of Sciences (CAS), have been working to develop a global OGCM and a global coupled ocean-atmosphere general circulation model (CGCM). From the original flux anomaly-coupling model developed in the beginning of the 1990s to the latest directly-coupling model, LASG scientists have developed four global coupled GCMs. This study summarizes the development history of these models and describes the third and fourth coupled GCMs and selected applications. Strengths and weaknesses of these models are highlighted.

  2. A simulation of the winter and summer circulations with the NMC Global Spectral Model

    NASA Technical Reports Server (NTRS)

    Kinter, J. L., III; Shukla, J.; Marx, L.; Schneider, E. K.

    1988-01-01

    The medium range forecast model of the NMC has been integrated to produce winter and summer simulations. It is found that the model climatology is similar to that of the observed atmosphere as well as climatologies of other general circulation models. The stationary and transient features of the model circulation are described, including both tropical and extratropical regions. The model hydrological cycle, radiative balance, and surface heat budget are discussed. Comparison with observations shows that the model is colder than that observed in the troposphere and cools in the lower stratosphere in the tropics and near the poles in both simulations. It is suggested that the upper branch of the Hadley cell is poorly simulated in the integrated model. The simulations are in reasonable agreement with the observations in sea level pressure, the structure of the tropospheric zonal jets, and the winter hemispheric stationary waves.

  3. Contribution of dietary advanced glycation end products (AGE) to circulating AGE: role of dietary fat.

    PubMed

    Davis, Kathleen E; Prasad, Chandan; Vijayagopal, Parakat; Juma, Shanil; Adams-Huet, Beverley; Imrhan, Victorine

    2015-12-14

    The purpose of this pilot study was to determine whether macronutrient content (low-fat v. high-fat diet) influences an indicator of advanced glycation end products (AGE), N(ε) carboxymethyl-lysine (CML), in the context of a 1-d, high-AGE diet. The effect of the diets on inflammatory markers was also assessed. A total of nineteen overweight and obese adults (nine men and ten women) without known disease were recruited to participate in a crossover challenge of a high-fat, high-AGE (HFHA) and low-fat, high-AGE (LFHA) diet. In each phase patients had fasting blood drawn, followed by consumption of a high-fat or low-fat breakfast test meal, then three postprandial blood draws at 1, 2 and 3 h after consuming the test meal. After consuming high-AGE meals for the remainder of the day, participants returned the next day for a follow-up analysis. A different pattern in the 3-h post-meal CML and soluble receptor for AGE response to the two diets was observed (P=0·01 and 0·05, respectively). No change in serum CML was observed following consumption of a LFHA breakfast (535 (25th-75th percentile 451-790) to 495 (25th-75th percentile 391-682) ng/ml; P=0·36), whereas a rise in CML occurred after the HFHA breakfast (463 (25th-75th percentile 428-664) to 578 (25th-75th percentile 474-865) ng/ml; P=0·05). High sensitivity C-reactive protein and high molecular weight adiponectin were not affected by either diet. These findings suggest that dietary CML may not be as important in influencing serum CML as other dietary factors. In addition, acute exposure to dietary CML may not influence inflammation in adults without diabetes or kidney disease. This is contrary to previous findings.

  4. Observational and modeling studies of heat, moisture, precipitation, and global-scale circulation patterns

    NASA Technical Reports Server (NTRS)

    Vincent, Dayton G.; Robertson, Franklin

    1993-01-01

    The research sponsored by this grant is a continuation and an extension of the work conducted under a previous contract, 'South Pacific Convergence Zone and Global-Scale Circulations'. In the prior work, we conducted a detailed investigation of the South Pacific convergence zone (SPCZ), and documented many of its significant features and characteristics. We also conducted studies of its interaction with global-scale circulation features through the use of both observational and modeling studies. The latter was accomplished toward the end of the contract when Dr. James Hurrell, then a Ph.D. candidate, successfully ported the NASA GLA general circulation model (GCM) to Purdue University. In our present grant, we have expanded our previous research to include studies of other convectively-driven circulation systems in the tropics besides the SPCZ. Furthermore, we have continued to examine the relationship between these convective systems and global-scale circulation patterns. Our recent research efforts have focused on three objectives: (1) determining the periodicity of large-scale bands of organized convection in the tropics, primarily synoptic to intraseasonal time scales in the Southern Hemisphere; (2) examining the relative importance of tropical versus mid-latitude forcing for Southern Hemisphere summertime subtropical jets, particularly over the Pacific Ocean; and (3) estimating tropical precipitation, especially over oceans, using observational and budget methods. A summary list of our most significant accomplishments in the past year is given.

  5. Maturity Model for Advancing Smart Grid Interoperability

    SciTech Connect

    Knight, Mark; Widergren, Steven E.; Mater, J.; Montgomery, Austin

    2013-10-28

    Abstract—Interoperability is about the properties of devices and systems to connect and work properly. Advancing interoperability eases integration and maintenance of the resulting interconnection. This leads to faster integration, lower labor and component costs, predictability of projects and the resulting performance, and evolutionary paths for upgrade. When specifications are shared and standardized, competition and novel solutions can bring new value streams to the community of stakeholders involved. Advancing interoperability involves reaching agreement for how things join at their interfaces. The quality of the agreements and the alignment of parties involved in the agreement present challenges that are best met with process improvement techniques. The GridWise® Architecture Council (GWAC) sponsored by the United States Department of Energy is supporting an effort to use concepts from capability maturity models used in the software industry to advance interoperability of smart grid technology. An interoperability maturity model has been drafted and experience is being gained through trials on various types of projects and community efforts. This paper describes the value and objectives of maturity models, the nature of the interoperability maturity model and how it compares with other maturity models, and experiences gained with its use.

  6. Modeling and model validation of wind-driven circulation in Upper Klamath Lake, Oregon

    USGS Publications Warehouse

    Cheng, R.T.; Gartner, J.W.; Wood, T.

    2005-01-01

    The hydrodynamics in the Upper Klamath Lake (UKL) plays a significant role in the water quality conditions of the lake. In order to provide a quantitative evaluation of the impacts of hydrodynamics on water quality in UKL, a detailed hydrodynamic model was implemented using an unstructured grid 3-D hydrodynamic model known as the UnTRIM model. The circulation in UKL is driven primarily by wind. Wind speed and direction time-series records were used as input, the numerical model reproduced the wind "set-up" and "set-down" at down wind and upwind ends of the lake, respectively. Of the two acoustic Doppler current profiler (ADCP) records, the UnTRIM model reproduced the measured velocity at the deep station. At the shallow station, the model results showed diurnal patterns that correlated well with wind variations, but the measured velocity showed water velocity sustained at 3 to 5 cm/sec or above. Discrepancies between the model results and observations at the shallow ADCP station is discussed on the basis of correct physics. If the field measurements are inconsistent with the known physics, there exists the possibility that the field data are suspect or the field data are revealing some physical processes that are not yet understood. Copyright ASCE 2005.

  7. Modeling of clouds and radiation for developing parameterizations for general circulation models. Annual report, 1995

    SciTech Connect

    Toon, O.B.; Westphal, D.L.

    1996-07-01

    We have used a hierarchy of numerical models for cirrus and stratus clouds and for radiative transfer to improve the reliability of general circulation models. Our detailed cloud microphysical model includes all of the physical processes believed to control the lifecycles of liquid and ice clouds in the troposphere. We have worked on specific GCM parameterizations for the radiative properties of cirrus clouds, making use of a mesocale model as the test-bed for the parameterizations. We have also modeled cirrus cloud properties with a detailed cloud physics model to better understand how the radiatively important properties of cirrus are controlled by their environment. We have used another cloud microphysics model to investigate of the interactions between aerosols and clouds. This work is some of the first to follow the details of interactions between aerosols and cloud droplets and has shown some unexpected relations between clouds and aerosols. We have also used line-by- line radiative transfer results verified with ARM data, to derive a GCMS.

  8. Improvement in Geoid Models for Ocean Circulation Studies

    NASA Technical Reports Server (NTRS)

    Tapley, Byron D.; Chambers, Don P.; Poole, Steve; Ries, John c.

    2003-01-01

    At wavelengths of 500 km and longer, the GRACE GGM01 Model produces a significantly better marine geoid than any previous model. This conclusion follows from evaluating the geostrophic currents determined by combining the model with a mean sea surface from altimetry. The agreement with currents computed from a traditional hydrographic map is very close, which suggests that one of the primary missions of the TOPEX/POSEIDON mission, to determine the absolute dynamic ocean topography, may soon be met. This solution has been made available to the public at http://www.csr.utexs.edu/grace/gravity. The results reported in this paper have been presented at the 2003 EGS-AGU-EUG Joint Assembly. Two articles are currently being prepared for Geophysical Research Letters to summarize these results.

  9. Aeroheating model advancements featuring electroless metallic plating

    NASA Technical Reports Server (NTRS)

    Stalmach, C. J., Jr.; Goodrich, W. D.

    1976-01-01

    Discussed are advancements in wind tunnel model construction methods and hypersonic test data demonstrating the methods. The general objective was to develop model fabrication methods for improved heat transfer measuring capability at less model cost. A plated slab model approach was evaluated with cast models containing constantan wires that formed single-wire-to-plate surface thermocouple junctions with a seamless skin of electroless nickel alloy. The surface of a space shuttle orbiter model was selectively plated with scaled tiles to simulate, with high fidelity, the probable misalignments of the heatshield tiles on a flight vehicle. Initial, Mach 8 heating results indicated a minor effect of tile misalignment roughness on boundary layer transition, implying a possible relaxation of heatshield manufacturing tolerances. Some loss of the plated tiles was experienced when the model was tested at high heating rates.

  10. Evaluation of a stratiform cloud parameterization for general circulation models

    SciTech Connect

    Ghan, S.J.; Leung, L.R.; McCaa, J.

    1996-04-01

    To evaluate the relative importance of horizontal advection of cloud versus cloud formation within the grid cell of a single column model (SCM), we have performed a series of simulations with our SCM driven by a fixed vertical velocity and various rates of horizontal advection.

  11. Development of the Circulation Control Flow Scheme Used in the NTF Semi-Span FAST-MAC Model

    NASA Technical Reports Server (NTRS)

    Jones, Gregory S.; Milholen, William E., II; Chan, David T.; Allan, Brian G.; Goodliff, Scott L.; Melton, Latunia P.; Anders, Scott G.; Carter, Melissa B.; Capone, Francis J.

    2013-01-01

    The application of a circulation control system for high Reynolds numbers was experimentally validated with the Fundamental Aerodynamic Subsonic Transonic Modular Active Control semi-span model in the NASA Langley National Transonic Facility. This model utilized four independent flow paths to modify the lift and thrust performance of a representative advanced transport type of wing. The design of the internal flow paths highlights the challenges associated with high Reynolds number testing in a cryogenic pressurized wind tunnel. Weight flow boundaries for the air delivery system were identified at mildly cryogenic conditions ranging from 0.1 to 10 lbm/sec. Results from the test verified system performance and identified solutions associated with the weight-flow metering system that are linked to internal perforated plates used to achieve flow uniformity at the jet exit.

  12. A Nd Isotopic Composition Modeling Approach of the Oceanic Thermohaline Circulation Change During LGM

    NASA Astrophysics Data System (ADS)

    Arsouze, T.; Dutay, J.; Lacan, F.; Jeandel, C.; Alkama, R.; Kageyama, M.; Piotrowski, A.

    2006-12-01

    The role of thermohaline circulation in climate change has been a matter of debate for a long time. Proxies of past ocean circulation such as δ13C or 231Pa/230Th suggest a relationship between North Atlantic Deep Water (NADW) strength and rapid climate change. Neodymium isotopic composition (Nd IC) is a quasi conservative geochemical tracer of water masses in the ocean interior and thus can be used as a proxy for NADW. Seawater Nd IC being recorded in marine sediments, this proxy is used to infer paleo-circulations on various time scales. Recent studies of Nd IC records, in the ferromanganese oxide components of a South Atlantic core, confirm the close relation between thermohaline circulation and North Atlantic climate changes through the last deglaciation (Piotrowski et al., 2004). Our purpose here is to model the Nd IC during the LGM and the Holocene with the Ocean Global Circulation Model NEMO, in the ORCA2 (2°) configuration. The explicit simulation of this proxy in the model allows to investigate and quantify the circulation change that corresponds to the Nd isotopic composition variation recorded in the sediments. We consider that the main source of Nd into the ocean is the interaction between water masses and continental margins (Boundary Exchange process; (Lacan and Jeandel, 2005). Boundary exchange is parameterized using a relaxing term (Arsouze et al., 2006). Simulated Nd IC distributions are evaluated by comparison with available records for the LGM and Holocene. References: Arsouze, T., Dutay, J.-C., Lacan, F. and Jeandel, C., 2006. Modeling the neodymium isotopic composition with a global ocean circulation model Chemical Geology, in press. Lacan, F. and Jeandel, C., 2005. Neodymium isotopes as a new tool for quantifying exchange fluxes at the continent - ocean interface. Earth and Planetary Science Letters, 232(3-4): 245-257. Piotrowski, A.M., Goldstein, S.L., Hemming, S.R. and Fairbanks, R.G., 2004. Intensification and variability of ocean

  13. Model for a pump that drives circulation of pleural fluid.

    PubMed

    Butler, J P; Huang, J; Loring, S H; Lai-Fook, S J; Wang, P M; Wilson, T A

    1995-01-01

    Physical and mathematical models were used to study a mechanism that could maintain the layer of pleural fluid that covers the surface of the lung. The pleural space was modeled as a thin layer of viscous fluid lying between a membrane carrying tension (T), representing the lung, and a rigid wall, representing the chest wall. Flow of the fluid was driven by sliding between the membrane and wall. The physical model consisted of a cylindrical balloon with strings stretched along its surface. When the balloon was inflated inside a vertical circular cylinder containing a viscous fluid, the strings formed narrow vertical channels between broad regions in which the balloon pressed against the outer cylinder. The channels simulated the pleural space in the regions of lobar margins. Oscillatory rotation of the outer cylinder maintained a lubricating layer of fluid between the balloon and the cylinder. The thickness of the fluid layer (h), measured by fluorescence videomicroscopy, was larger for larger fluid viscosity (mu), larger sliding velocity (U), and smaller pressure difference (delta P) between the layer and the channel. A mathematical model of the flow in a horizontal section was analyzed, and numerical solutions were obtained for parameter values of mu, U, delta P, and T that matched those of the physical model. The computed results agreed reasonably well with the experimental results. Scaling laws yield the prediction that h is approximately (T/delta P)(microU/T)2/3. For physiological values of the parameters, the predicted value of h is approximately 10(-3) cm, in good agreement with the observed thickness of the pleural space.

  14. A simple hydrologically based model of land surface water and energy fluxes for general circulation models

    NASA Technical Reports Server (NTRS)

    Liang, XU; Lettenmaier, Dennis P.; Wood, Eric F.; Burges, Stephen J.

    1994-01-01

    A generalization of the single soil layer variable infiltration capacity (VIC) land surface hydrological model previously implemented in the Geophysical Fluid Dynamics Laboratory (GFDL) general circulation model (GCM) is described. The new model is comprised of a two-layer characterization of the soil column, and uses an aerodynamic representation of the latent and sensible heat fluxes at the land surface. The infiltration algorithm for the upper layer is essentially the same as for the single layer VIC model, while the lower layer drainage formulation is of the form previously implemented in the Max-Planck-Institut GCM. The model partitions the area of interest (e.g., grid cell) into multiple land surface cover types; for each land cover type the fraction of roots in the upper and lower zone is specified. Evapotranspiration consists of three components: canopy evaporation, evaporation from bare soils, and transpiration, which is represented using a canopy and architectural resistance formulation. Once the latent heat flux has been computed, the surface energy balance is iterated to solve for the land surface temperature at each time step. The model was tested using long-term hydrologic and climatological data for Kings Creek, Kansas to estimate and validate the hydrological parameters, and surface flux data from three First International Satellite Land Surface Climatology Project Field Experiment (FIFE) intensive field campaigns in the summer-fall of 1987 to validate the surface energy fluxes.

  15. Modeling of clouds and radiation for developing parameterizations for general circulation models. Annual report, 1994

    SciTech Connect

    1994-12-31

    We are using a hierarchy of numerical models of cirrus and stratus clouds and radiative transfer to improve the reliability of general circulation models. Our detailed cloud microphysical model includes all of the physical processes believed to control the lifecycle of liquid and ice clouds in the troposphere. In our one-dimensional cirrus studies, we find that the ice crystal number and size in cirrus clouds are not very sensitive to the number of condensation nuclei which are present. We have compared our three-dimensional meoscale simulations of cirrus clouds with radar, lidar satellite and other observations of water vapor and cloud fields and find that the model accurately predicts the characteristics of a cirrus cloud system. The model results reproduce several features detected by remote sensing (lidar and radar) measurements, including the appearance of the high cirrus cloud at about 15 UTC and the thickening of the cloud at 20 UTC. We have developed a new parameterizations for production of ice crystals based on the detailed one-dimensional cloud model, and are presently testing the parameterization in three-dimensional simulations of the FIRE-II November 26 case study. We have analyzed NWS radiosonde humidity data from FIRE and ARM and found errors, biases, and uncertainties in the conversion of the sensed resistance to humidity.

  16. A thermosphere/ionosphere general circulation model with coupled electrodynamics

    NASA Technical Reports Server (NTRS)

    Richmond, A. D.; Ridley, E. C.; Roble, R. G.

    1992-01-01

    A new simulation model of upper atmospheric dynamics is presented that includes self-consistent electrodynamic interactions between the thermosphere and ionosphere. This model calculates the dynamo effects of thermospheric winds, and uses the resultant electric fields and currents in calculating the neutral and plasma dynamics. A realistic geomagnetic field geometry is used. Sample simulations for solar maximum equinox conditions illustrate two previously predicted effects of the feedback. Near the magnetic equator, the afternoon uplift of the ionosphere by an eastward electric field reduces ion drag on the neutral wind, so that relatively strong eastward winds can occur in the evening. In addition, a vertical electric field is generated by the low-latitude wind, which produces east-west plasma drifts in the same direction as the wind, further reducing the ion drag and resulting in stronger zonal winds.

  17. Observations and Modeling of the Shelf Circulation North of the Monterey Bay during August 2006

    DTIC Science & Technology

    2007-06-01

    the three ocean models (HOPS, ROMS and NCOM/ICON) used during the MB06 real-time operations diffusivities estimated using (i) a simple turbulent ... MODELING OF THE SHELF CIRCULATION NORTH OF THE MONTEREY BAY DURING AUGUST 2006 by Rebecca E. Wolf June 2007 Thesis Advisor: Steven R...ONLY (Leave blank) 2. REPORT DATE June 2007 3. REPORT TYPE AND DATES COVERED Master’s Thesis 4. TITLE AND SUBTITLE Observations and Modeling of

  18. An implementation of a barotropic quasigeostrophic model of ocean circulation on the MPP

    NASA Technical Reports Server (NTRS)

    Grosch, C. E.; Fatoohi, R.

    1987-01-01

    The implementation on the Massively Parallel Processor (MPP) of a barotropic quasigeostrophic model of ocean circulation is discussed. The mathematical model, including scalings and boundary conditions is discussed. The numerical scheme, which uses compact differencing is also discussed. The implementation of this model on the MPP is then presented. Finally, some performance results are given and compared to results obtained using the VPS-32 and one processor of a CRAY-2.

  19. Selected translated abstracts of Russian-language climate-change publications. 4: General circulation models

    SciTech Connect

    Burtis, M.D.; Razuvaev, V.N.; Sivachok, S.G.

    1996-10-01

    This report presents English-translated abstracts of important Russian-language literature concerning general circulation models as they relate to climate change. Into addition to the bibliographic citations and abstracts translated into English, this report presents the original citations and abstracts in Russian. Author and title indexes are included to assist the reader in locating abstracts of particular interest.

  20. Modelling Circulating Tumour Cells for Personalised Survival Prediction in Metastatic Breast Cancer

    PubMed Central

    2015-01-01

    Ductal carcinoma is one of the most common cancers among women, and the main cause of death is the formation of metastases. The development of metastases is caused by cancer cells that migrate from the primary tumour site (the mammary duct) through the blood vessels and extravasating they initiate metastasis. Here, we propose a multi-compartment model which mimics the dynamics of tumoural cells in the mammary duct, in the circulatory system and in the bone. Through a branching process model, we describe the relation between the survival times and the four markers mainly involved in metastatic breast cancer (EPCAM, CD47, CD44 and MET). In particular, the model takes into account the gene expression profile of circulating tumour cells to predict personalised survival probability. We also include the administration of drugs as bisphosphonates, which reduce the formation of circulating tumour cells and their survival in the blood vessels, in order to analyse the dynamic changes induced by the therapy. We analyse the effects of circulating tumour cells on the progression of the disease providing a quantitative measure of the cell driver mutations needed for invading the bone tissue. Our model allows to design intervention scenarios that alter the patient-specific survival probability by modifying the populations of circulating tumour cells and it could be extended to other cancer metastasis dynamics. PMID:25978366

  1. Documentation of a ground hydrology parameterization for use in the GISS atmospheric general circulation model

    NASA Technical Reports Server (NTRS)

    Lin, J. D.; Aleano, J.; Bock, P.

    1978-01-01

    The moisture transport processes related to the earth's surface relevant to the ground circulation model GCM are presented. The GHM parametrizations considered are: (1) ground wetness and soil parameters; (2) precipitation; (3) evapotranspiration; (4) surface storage of snow and ice; and (5) runout. The computational aspects of the GHM using computer programs and flow charts are described.

  2. Simulation of the Low-Level-Jet by general circulation models

    SciTech Connect

    Ghan, S.J.

    1996-04-01

    To what degree is the low-level jet climatology and it`s impact on clouds and precipitation being captured by current general circulation models? It is hypothesised that a need for a pramaterization exists. This paper describes this parameterization need.

  3. A PARALLEL IMPLEMENTATION OF A SPECTRAL ELEMENT OCEAN MODEL FOR SIMULATING LOW-LATITUDE CIRCULATION SYSTEM

    SciTech Connect

    MA,H.; MCCAFFREY,J.; PIACSEK,S.

    1997-11-01

    This paper is about the parallel implementation of a high-resolution, spectral element, primitive equation model of a homogeneous equatorial ocean. The present work shows that the high-order domain decomposition methods can be efficiently implemented in a massively parallel computing environment to solve large-scale CFD problems, such as the general circulation of the ocean.

  4. Variational Data Assimilative Modeling of the Gulf of Maine Circulation in Spring and Summer 2010.

    PubMed

    Li, Yizhen; He, Ruoying; Chen, Ke; McGillicuddy, Dennis J

    2015-05-01

    A data assimilative ocean circulation model is used to hindcast the Gulf of Maine (GOM) circulation in spring and summer 2010. Using the recently developed incremental strong constraint 4D Variational data assimilation algorithm, the model assimilates satellite sea surface temperature and in situ temperature and salinity profiles measured by expendable bathythermograph, Argo floats, and shipboard CTD casts. Validation against independent observations shows that the model skill is significantly improved after data assimilation. The data-assimilative model hindcast reproduces the temporal and spatial evolution of the ocean state, showing that a sea level depression southwest of the Scotian Shelf played a critical role in shaping the gulf-wide circulation. Heat budget analysis further demonstrates that both advection and surface heat flux contribute to temperature variability. The estimated time scale for coastal water to travel from the Scotian Shelf to the Jordan Basin is around 60 days, which is consistent with previous estimates based on in situ observations. Our study highlights the importance of resolving upstream and offshore forcing conditions in predicting the coastal circulation in the GOM.

  5. Observations and Modeling of the Transient General Circulation of the North Pacific Basin

    NASA Technical Reports Server (NTRS)

    McWilliams, James C.

    2000-01-01

    Because of recent progress in satellite altimetry and numerical modeling and the accumulation and archiving of long records of hydrographic and meteorological variables, it is becoming feasible to describe and understand the transient general circulation of the ocean (i.e., variations with spatial scales larger than a few hundred kilometers and time scales of seasonal and longer-beyond the mesoscale). We have carried out various studies in investigation of the transient general circulation of the Pacific Ocean from a coordinated analysis of satellite altimeter data, historical hydrographic gauge data, scatterometer wind observations, reanalyzed operational wind fields, and a variety of ocean circulation models. Broadly stated, our goal was to achieve a phenomenological catalogue of different possible types of large-scale, low-frequency variability, as a context for understanding the observational record. The approach is to identify the simplest possible model from which particular observed phenomena can be isolated and understood dynamically and then to determine how well these dynamical processes are represented in more complex Oceanic General Circulation Models (OGCMs). Research results have been obtained on Rossby wave propagation and transformation, oceanic intrinsic low-frequency variability, effects of surface gravity waves, pacific data analyses, OGCM formulation and developments, and OGCM simulations of forced variability.

  6. Applications of kinetic theory. Predictive models of circulating fluidized bed combustors: Tenth technical progress report

    SciTech Connect

    Gidaspow, D.

    1992-01-01

    The overall objective of this investigation is to develop experimentally verified models for circulating fluidized bed (CFB) combustors. This report presents the author`s derivation of analytical solutions useful in understanding the operation of a CFB. The report is in a form of a chapter that reviews the kinetic theory applications.

  7. On the design of an interactive biosphere for the GLAS general circulation model

    NASA Technical Reports Server (NTRS)

    Mintz, Y.; Sellers, P. J.; Willmott, C. J.

    1983-01-01

    Improving the realism and accuracy of the GLAS general circulation model (by adding an interactive biosphere that will simulate the transfers of latent and sensible heat from land surface to atmosphere as functions of the atmospheric conditions and the morphology and physiology of the vegetation) is proposed.

  8. Circulating Tumour Cells as an Independent Prognostic Factor in Patients with Advanced Oesophageal Squamous Cell Carcinoma Undergoing Chemoradiotherapy

    PubMed Central

    Su, Po-Jung; Wu, Min-Hsien; Wang, Hung-Ming; Lee, Chia-Lin; Huang, Wen-Kuan; Wu, Chiao-En; Chang, Hsien-Kun; Chao, Yin-Kai; Tseng, Chen-Kan; Chiu, Tzu-Keng; Lin, Nina Ming-Jung; Ye, Siou-Ru; Lee, Jane Ying-Chieh; Hsieh, Chia-Hsun

    2016-01-01

    The role of circulating tumour cells (CTCs) in advanced oesophageal cancer (EC) patients undergoing concurrent chemoradiotherapy (CCRT) remains uncertain. A negative selection protocol plus flow cytometry was validated to efficiently identify CTCs. The CTC number was calculated and analysed for survival impact. The protocol’s efficacy in CTC identification was validated with a recovery rate of 44.6 ± 9.1% and a coefficient of variation of 20.4%. Fifty-seven patients and 20 healthy donors were enrolled. Initial staging, first response to CRT, and surgery after CRT were prognostic for overall survival, with P values of <0.0001, <0.0001, and <0.0001, respectively. The CTC number of EC patients is significantly higher (P = 0.04) than that of healthy donors. Multivariate analysis for disease-specific progression-free survival showed that surgery after response to CCRT, initial stage, and CTC number (≥21.0 cells/mL) played independent prognostic roles. For overall survival, surgery after CCRT, performance status, initial stage, and CTC number were significant independent prognostic factors. In conclusion, a negative selection plus flow cytometry protocol efficiently detected CTCs. The CTC number before CCRT was an independent prognostic factor in patients with unresectable oesophageal squamous cell carcinoma. Further large-scale prospective studies for validation are warranted. PMID:27530152

  9. Circulating serum microRNA-345 correlates with unfavorable pathological response to preoperative chemoradiotherapy in locally advanced rectal cancer

    PubMed Central

    Yu, Jing; Li, Ning; Wang, Xin; Ren, Hua; Wang, Weihu; Wang, Shulian; Song, Yongwen; Liu, Yueping; Li, Yexiong; Zhou, Xuantong; Luo, Aiping; Liu, Zhihua; Jin, Jing

    2016-01-01

    Preoperative chemoradiotherapy (pre-CRT) has been represented as the standard treatment for locally advanced rectal cancer (LARC), but large variations of tumor radiation response to CRT have been reported in the clinic. To explore the function of microRNAs as potential therapeutic predictors of pre-CRT pathological response in LARC, we analyzed global miRNA expression in CRT-sensitive and CRT-resistant groups before treatment. MiR-345 was significantly elevated in the CRT-resistant group. Therefore, miR-345 was selected as a candidate for further analysis. We assessed the correlation between the miRNA signatures and the chemoradiotherapeutic response in 20 randomly selected LARC tissue samples (Validation set) and 87 serum samples (Training set) by qRT-PCR. Further, we validated the results in 42 randomly selected LARC serum samples (Validation set). High miR-345 expression was significantly correlated with unfavorable pre-CRT pathological response in tissue and serum. Moreover, low miR-345 levels predicted superior 3-year local recurrence free survival (LRFS). Taken together, circulating serum miR-345 correlates with unfavorable pre-CRT response and poor locoregional control in LARC. It might be a promising biomarker to facilitate patient stratification for personalized treatment. PMID:27572313

  10. Atmospheric circulation modeling of super Earths and terrestrial extrasolar planets using the SPARC/MITgcm

    NASA Astrophysics Data System (ADS)

    Kataria, T.; Showman, A. P.; Haberle, R. M.; Marley, M. S.; Fortney, J. J.; Freedman, R. S.

    2013-12-01

    The field of exoplanets continues to be a booming field of research in astronomy and planetary science, with numerous ground-based (e.g., SuperWASP, HARPS-N and S) and space-based surveys (e.g., Kepler) that detect and characterize planets ranging from hot Jupiters, Jovian-sized planets orbiting less than 0.1 AU from their star, to super Earths and terrestrial exoplanets, planets that have masses equal to or less than 10 times that of Earth with a range of orbital distances. Atmospheric circulation modeling plays an important role in the characterization of these planets, helping to constrain observations that probe their atmospheres. These models have proven successful in understanding observations of transiting exoplanets (when the planet passes in front of the star along our line of sight) particularly when the planet is passing through secondary eclipse (when the planet's dayside is visible). In modeling super Earths and terrestrial exoplanets, we must consider not only planets with thick fluid envelopes, but also traditional terrestrial planets with solid surfaces and thinner atmospheres. To that end, we present results from studies investigating the atmospheric circulation of these classes of planets using the SPARC/MITgcm, a state-of-the-art model which couples the MIT General Circulation Model with a plane-parallel, two-stream, non-gray radiative transfer model. We will present results from two studies, the first focusing on the circulation of GJ 1214b, a super-Earth detected by the MEarth ground-based survey, and a second study which explores the circulation of terrestrial exoplanets orbiting M-dwarfs.

  11. The Early Jurassic climate: General circulation model simulations and the paleoclimate record

    SciTech Connect

    Chandler, M.A.

    1992-01-01

    This thesis presents the results of several general circulation model simulations of the Early Jurassic climate. The general circulation model employed was developed at the Goddard Institute for Space Studies while most paleoclimate data were provided by the Paleographic Atlas Project of the University of Chicago. The first chapter presents an Early Jurassic base simulation, which uses detailed reconstructions of paleogeography, vegetation, and sea surface temperature as boundary condition data sets. The resulting climatology reveals an Earth 5.2[degrees]C warmer, globally, than at present and a latitudinal temperature gradient dominated by high-latitude warming (+20[degrees]C) and little tropical change (+1[degrees]C). Comparisons show a good correlation between simulated results and paleoclimate data. Sensitivity experiments are used to investigate any model-data mismatches. Chapters two and three discuss two important aspects of Early Jurassic climate, continental aridity and global warming. Chapter two focuses on the hydrological capabilities of the general circulation model. The general circulation model's hydrologic diagnostics are evaluated, using the distribution of modern deserts and Early Jurassic paleoclimate data as validating constraints. A new method, based on general circulation model diagnostics and empirical formulae, is proposed for evaluating moisture balance. Chapter three investigates the cause of past global warming, concentrating on the role of increased ocean heat transport. Early Jurassic simulations show that increased ocean heat transports may have been a major factor in past climates. Increased ocean heat transports create latitudinal temperature gradients that closely approximate paleoclimate data and solve the problem of tropical overheating that results from elevated atmospheric carbon dioxide. Increased carbon dioxide cannot duplicate the Jurassic climate without also including increased ocean heat transports.

  12. Advanced Technology System Scheduling Governance Model

    SciTech Connect

    Ang, Jim; Carnes, Brian; Hoang, Thuc; Vigil, Manuel

    2015-06-11

    In the fall of 2005, the Advanced Simulation and Computing (ASC) Program appointed a team to formulate a governance model for allocating resources and scheduling the stockpile stewardship workload on ASC capability systems. This update to the original document takes into account the new technical challenges and roles for advanced technology (AT) systems and the new ASC Program workload categories that must be supported. The goal of this updated model is to effectively allocate and schedule AT computing resources among all three National Nuclear Security Administration (NNSA) laboratories for weapons deliverables that merit priority on this class of resource. The process outlined below describes how proposed work can be evaluated and approved for resource allocations while preserving high effective utilization of the systems. This approach will provide the broadest possible benefit to the Stockpile Stewardship Program (SSP).

  13. Validation of Atmospheric Dynamics (VADY) - representation of circulation types/dynamical modes in the decadal-prediction model system of MPI-ESM

    NASA Astrophysics Data System (ADS)

    Lang, Benjamin; Jacobeit, Jucundus; Beck, Christoph; Philipp, Andreas

    2016-04-01

    The climate research program "Medium-range Climate Predictions" (MiKlip), funded by the Federal Ministry of Education and Research in Germany (BMBF), has the aim to improve a climate model system (MPI-ESM) in such a way that it can provide reliable decadal predictions of climate, including extreme weather events. A substantial part of the development process is a comprehensive model validation. Within MiKlip, it includes comparisons of model simulations and observations in order to allow statements about the performance of the model and to give particular recommendations for the further development of the model. The research project "Validation of Atmospheric Dynamics" (VADY), conducted by the cooperation partners "Institute of Geography at the University of Augsburg" (IGUA) and the "German Aerospace Centre" (DLR), contributes to model validation within MiKlip with a special focus on atmospheric waves (DLR) and circulation dynamics (IGUA). Within the framework of VADY, DLR validates the representation of atmospheric waves on different levels and scales based on suitable activity indices (e.g. the so-called large-scale dynamical activity index (LDAI), which is a measure for the activity of planetary waves). The focus of IGUA is on the model validation with respect to the representation of atmospheric circulation types, dynamical modes and the teleconnectivity of the atmospheric circulation. The present contribution provides results of the model validation concerning circulation types/dynamical modes. Results are shown for both the frequency of occurrence and internal characteristics (e. g. persistence or intensity), and for different classification methods (e. g. based on PCA or clustering techniques). The representation of circulation types/dynamical modes will be compared for different generations of the MPI-ESM decadal-prediction model (baseline0, baseline1, prototype) in order to clarify both advances and limitations in the development of the model. Furthermore

  14. On a sparse pressure-flow rate condensation of rigid circulation models.

    PubMed

    Schiavazzi, D E; Hsia, T Y; Marsden, A L

    2016-07-26

    Cardiovascular simulation has shown potential value in clinical decision-making, providing a framework to assess changes in hemodynamics produced by physiological and surgical alterations. State-of-the-art predictions are provided by deterministic multiscale numerical approaches coupling 3D finite element Navier Stokes simulations to lumped parameter circulation models governed by ODEs. Development of next-generation stochastic multiscale models whose parameters can be learned from available clinical data under uncertainty constitutes a research challenge made more difficult by the high computational cost typically associated with the solution of these models. We present a methodology for constructing reduced representations that condense the behavior of 3D anatomical models using outlet pressure-flow polynomial surrogates, based on multiscale model solutions spanning several heart cycles. Relevance vector machine regression is compared with maximum likelihood estimation, showing that sparse pressure/flow rate approximations offer superior performance in producing working surrogate models to be included in lumped circulation networks. Sensitivities of outlets flow rates are also quantified through a Sobol׳ decomposition of their total variance encoded in the orthogonal polynomial expansion. Finally, we show that augmented lumped parameter models including the proposed surrogates accurately reproduce the response of multiscale models they were derived from. In particular, results are presented for models of the coronary circulation with closed loop boundary conditions and the abdominal aorta with open loop boundary conditions.

  15. Century-scale variability in a randomly forced, two-dimensional thermohaline ocean circulation model

    SciTech Connect

    Mysak, L.A.; Stocker, T.F.; Huang, F.

    1993-01-01

    The response of a two-dimensional thermohaline ocean circulation model to a random freshwater flux superimposed on the usual mixed boundary conditions for temperature and salinity is considered. It is shown that for a wide range of vertical and horizontal diffusivities and a box geometry that approximates the Atlantic Ocean, 200-300 yr period oscillations exist in the basic-state, interhemispheric meridional overturning circulation with deep convection in the north. These fluctuations can also be described in terms of propagating salinity anomalies which travel in the direction of the thermohaline flow. For large horizontal (K{sub h} = 15 x 10{sup 3} m{sup 2}/s) and small vertical (K{sub v}=0.5 x 10{sup -4}m{sup 2}/s) diffusivities, the random forcing also excites deca-millennial oscillations in the basic structure of the thermohaline circulation. In this case, the meridional circulation pattern slowly oscillates between three different stages: a large positive cell, with deep convection in the North Atlantic and upwelling in the south; a symmetric two-cell circulation, with deep convection in both polar regions and upwelling near the equator; and a large negative cell, with deep convection in the South Atlantic and upwelling in the north. Each state can persist for 0 (10 kyr).

  16. Tropospheric energy cascades in a global circulation model

    NASA Astrophysics Data System (ADS)

    Brune, Sebastian; Becker, Erich

    2010-05-01

    The global horizontal kinetic energy (KE) spectrum and its budget are analyzed using results from a mechanistic GCM. The model has a standard spectral dynamical core with very high vertikal resolution up to the middle stratosphere (T330/L100). As a turbulence model we combine the Smagorinsky scheme with an energy conserving hyperdiffusion that is applied for the very smallest resolved scales. The simulation confirms a slope of the KE spectrum close to -3 in the synoptic regime where the KE is dominated by vortical modes. Towards the mesoscales the spectrum flattens and assumes a slope close to -5/3. Here divergent modes become increasingly important and even dominate the KE. Our complete analysis of the sinks and sources in the spectral KE budget reveals the overall energy fluxes through the spectrum. For the upper troposphere, the change of KE due to horizontal advection is negative for large synoptic scales. It is positive for the planetary scale, as expected, and for the mesoscales as well. This implies that the mesoscales, which include the dynamical sources of tropospheric gravity waves, are in fact sustained by the energy injection at the baroclinic scale (forward energy cascade). We find an enstrophy cascade in accordance with 2D turbulence, but zero downscaling of energy due to the vortical modes alone. In other words, the forward energy cascade in the synoptic and mesoscale regime is solely due to the divergent modes and their nonlinear interaction with the vortical modes. This picture, derived form a mechanistic model, not only lends further evidence for a generally forward energy cascade in the upper tropospheric away from the baroclinic scale. It also extends the picture proposed earlier by Tung and Orlando: The transition from a -3 to a -5/3 slope in the tropospheric macroturbulence spectrum reflects the fact, that the energy cascade due to the horizontally divergent (3D) modes is hidden behind the (2D) enstrophy cascade in the synoptic regime but

  17. A zonally symmetric model for volcanic influence upon atmospheric circulation

    NASA Technical Reports Server (NTRS)

    Schatten, K. H.; Mayr, H. G.; Harris, I.; Taylor, H. A., Jr.

    1984-01-01

    The effects of volcanic activity upon zonal wind flow in a model atmosphere are considered. A low latitude volcanic eruption could lower the tropospheric pole to equator temperature difference and thereby affect the atmospheric motions. When the temperature contrast decreases, the zonal wind velocities at high altitudes are reduced. To conserve angular momentum, the velocities in the lower atmosphere near the surface must increase, thus providing a momentum source for ocean currents. It is suggested that this momentum source may have played a role as a trigger for inducing the 1982-83 anomalous El Nino and possibly other climate changes.

  18. A zonally symmetric model for volcanic influence upon atmospheric circulation

    NASA Astrophysics Data System (ADS)

    Schatten, K. H.; Mayr, H. G.; Harris, I.; Taylor, H. A., Jr.

    1984-04-01

    The effects of volcanic activity upon zonal wind flow in a model atmosphere are considered. A low latitude volcanic eruption could lower the tropospheric pole to equator temperature difference and thereby affect the atmospheric motions. When the temperature contrast decreases, the zonal wind velocities at high altitudes are reduced. To conserve angular momentum, the velocities in the lower atmosphere near the surface must increase, thus providing a momentum source for ocean currents. It is suggested that this momentum source may have played a role as a trigger for inducing the 1982-83 anomalous El Nino and possibly other climate changes.

  19. The Venus nitric oxide night airglow - Model calculations based on the Venus Thermospheric General Circulation Model

    NASA Technical Reports Server (NTRS)

    Bougher, S. W.; Gerard, J. C.; Stewart, A. I. F.; Fesen, C. G.

    1990-01-01

    The mechanism responsible for the Venus nitric oxide (0,1) delta band nightglow observed in the Pioneer Venus Orbiter UV spectrometer (OUVS) images was investigated using the Venus Thermospheric General Circulation Model (Dickinson et al., 1984), modified to include simple odd nitrogen chemistry. Results obtained for the solar maximum conditions indicate that the recently revised dark-disk average NO intensity at 198.0 nm, based on statistically averaged OUVS measurements, can be reproduced with minor modifications in chemical rate coefficients. The results imply a nightside hemispheric downward N flux of (2.5-3) x 10 to the 9th/sq cm sec, corresponding to the dayside net production of N atoms needed for transport.

  20. The NASA/Ames Mars General Circulation Model: Model Improvements and Comparison with Observations

    NASA Technical Reports Server (NTRS)

    Haberle, R. M.; Hollingsworth, J. L.; Colaprete, A.; Bridger, A. F. C.; McKay, C. P.; Murphy, J. R.; Schaeffer, J.; Freedman, R.; Fonda, Mark (Technical Monitor)

    2003-01-01

    For many years, the NASA/Ames Mars General Circulation Model (GCM) has been built around the UCLA B-grid dynamical core. An attached tracer transport scheme based on the aerosol microphysical model of Toon et al. (1988) provided a tool for studying dust storm transport and feedbacks (Murphy et al., 1995). While we still use a B-grid version of the model, the Ames group is now transitioning to the ARIES/GEOS Goddard C-grid dynamical core (Suarez and Takacs, 1995). The C-grid produces smoother fields when the model top is raised above 50 km, and has a built in transport scheme for an arbitrary number of tracers. All of our transport simulations are now carried out with the C-grid. We have also been updating our physics package. Several years ago we replaced our bulk boundary layer scheme with a level 2 type diffusive scheme, and added a multi-level soil model (Haberle et al., 2000). More recently we replaced our radiation code with a more generalized two-stream code that accounts for aerosol multiple scattering and gaseous absorption. This code gives us much more flexibility in choosing aerosol optical properties and radiatively active gases.

  1. The puzzling Venusian polar atmospheric structure reproduced by a general circulation model

    PubMed Central

    Ando, Hiroki; Sugimoto, Norihiko; Takagi, Masahiro; Kashimura, Hiroki; Imamura, Takeshi; Matsuda, Yoshihisa

    2016-01-01

    Unlike the polar vortices observed in the Earth, Mars and Titan atmospheres, the observed Venus polar vortex is warmer than the midlatitudes at cloud-top levels (∼65 km). This warm polar vortex is zonally surrounded by a cold latitude band located at ∼60° latitude, which is a unique feature called ‘cold collar' in the Venus atmosphere. Although these structures have been observed in numerous previous observations, the formation mechanism is still unknown. Here we perform numerical simulations of the Venus atmospheric circulation using a general circulation model, and succeed in reproducing these puzzling features in close agreement with the observations. The cold collar and warm polar region are attributed to the residual mean meridional circulation enhanced by the thermal tide. The present results strongly suggest that the thermal tide is crucial for the structure of the Venus upper polar atmosphere at and above cloud levels. PMID:26832195

  2. Combustion modeling in advanced gas turbine systems

    SciTech Connect

    Smoot, L.D.; Hedman, P.O.; Fletcher, T.H.

    1995-10-01

    The goal of the U.S. Department of Energy`s Advanced Turbine Systems (ATS) program is to help develop and commercialize ultra-high efficiency, environmentally superior, and cost competitive gas turbine systems for base-load applications in the utility, independent power producer, and industrial markets. Combustion modeling, including emission characteristics, has been identified as a needed, high-priority technology by key professionals in the gas turbine industry.

  3. Anisotropic mesoscale eddy transport in ocean general circulation models

    NASA Astrophysics Data System (ADS)

    Reckinger, Scott; Fox-Kemper, Baylor; Bachman, Scott; Bryan, Frank; Dennis, John; Danabasoglu, Gokhan

    2014-11-01

    In modern climate models, the effects of oceanic mesoscale eddies are introduced by relating subgrid eddy fluxes to the resolved gradients of buoyancy or other tracers, where the proportionality is, in general, governed by an eddy transport tensor. The symmetric part of the tensor, which represents the diffusive effects of mesoscale eddies, is universally treated isotropically. However, the diffusive processes that the parameterization approximates, such as shear dispersion and potential vorticity barriers, typically have strongly anisotropic characteristics. Generalizing the eddy diffusivity tensor for anisotropy extends the number of parameters from one to three: major diffusivity, minor diffusivity, and alignment. The Community Earth System Model (CESM) with the anisotropic eddy parameterization is used to test various choices for the parameters, which are motivated by observations and the eddy transport tensor diagnosed from high resolution simulations. Simply setting the ratio of major to minor diffusivities to a value of five globally, while aligning the major axis along the flow direction, improves biogeochemical tracer ventilation and reduces temperature and salinity biases. These effects can be improved by parameterizing the oceanic anisotropic transport mechanisms.

  4. Results of various studies made with the NCAR Thermospheric General Circulation Model (TGCM) (invited review)

    NASA Technical Reports Server (NTRS)

    Roble, R. G.

    1986-01-01

    The NCAR thermospheric general circulation model (TGCM) has been used for a variety of thermospheric dynamic studies. It has also been used to compare model predictions with measurements made from various ground-based Fabry-Perot interferometer stations, incoherent scatter radar stations and the Dynamics Explorer satellites. The various input and output features of the model are described. These include the specification of solar EUV fluxes, and descriptions of empirical models to specify auroral particle precipitation, ion drag, and magnetospheric convection. Results are presented for solstice conditions giving the model perturbation temperature and circulation response to solar heating forcing alone and also with the inclusion of magnetospheric convections for two different dawn-dusk potential drops, 20 and 60 kV respectively. Results at two constant pressure levels Z =+1 at 300 km and Z= -4 at 120 km are presented for both the winter and summer polar cap regions. The circulation over the Northern Hemisphere polar cap in both the upper and lower thermosphere are presented along with a figure showing that the circulation is mainly a non-divergent irrotational flow responding to ion drag. The results of a study made on the Southern Hemisphere polar cap during October 1981 where Dynamics Explorer satellite measurements of winds, temperature and composition are compared to TGCM predictions are also presented. A diagnostic package that has been developed to analyze the balance of forces operating in the TGCM is presented next illustrating that in the F-region ion drag and pressure provide the main force balance and in the E-region ion drag, pressure and the coriolis forces provide the main balance. The TGCM prediction for the June 10, 1983 total solar eclipse are next presented showing a thermospheric disturbance following the path of totality. Finally, results are presented giving the global circulation, temperature and composition structure of the thermosphere for

  5. On the relevance of tidal forcing in modelling the Mediterranean thermohaline circulation

    NASA Astrophysics Data System (ADS)

    Sannino, G.; Carillo, A.; Pisacane, G.; Naranjo, C.

    2015-05-01

    The four dominant constituents of the semi-diurnal and diurnal tides have been implemented in a regional eddy-resolving Mediterranean version of the Massachusetts Institute of Technology general circulation model to assess the role played by tides on the simulated Mediterranean thermohaline circulation. To this aim we have compared two 10-year hindcast simulations differing only for the inclusion/omission of tidal forcing. Following the recent recommendations suggested by Sannino et al. (2014) both simulations use the same model having a substantial increment of the horizontal resolution in the region of the Strait of Gibraltar. The results suggest that application of explicit tidal forcing in a Mediterranean model has non negligible effects on the simulated circulation in addition to the expected intensification of local mixing processes. The western basin exhibits an immediate response to the different characteristics of the inflowing AW observable in the modified deep water convection processes in the Gulf of Lion. The inclusion of tidal forcing also induces changes in the intermediate circulation of the Tyrrhenian Sea bringing to a better representation of local structures and a reinforcement of the global thermohaline cell. LIW dispersal paths in the eastern basin are also affected by tides.

  6. Circulation of carbon dioxide in the mantle: multiscale modeling

    NASA Astrophysics Data System (ADS)

    Morra, G.; Yuen, D. A.; Lee, S.

    2012-12-01

    Much speculation has been put forward on the quantity and nature of carbon reservoirs in the deep Earth, because of its involvement in the evolution of life at the surface and inside planetary interiors. Carbon penetrates into the Earth's mantle mostly during subduction of oceanic crust, which contains carbonate deposits [1], however the form that it assumes at lower mantle depths is scarcely understood [2], hampering our ability to estimate the amount of carbon in the entire mantle by orders of magnitude. We present simulations of spontaneous degassing of supercritical CO2 using in-house developed novel implementations of the Fast-Multipole Boundary Element Method suitable for modeling two-phase flow (here mantle mineral and free CO2 fluid) through disordered materials such as porous rocks. Because the mutual interaction of droplets immersed either in a fluid or a solid matrix and their weakening effect to the host rock alters the strength of the mantle rocks, at the large scale the fluid phases in the mantle may control the creeping of mantle rocks [3]. In particular our study focuses on the percolation of supercritical CO2, estimated through the solution of the Laplace equation in a porous system, stochastically generated through a series of random Karhunen-Loeve decomposition. The model outcome is employed to extract the transmissivity of supercritical fluids in the mantle from the lowest scale up to the mantle scale and in combination with the creeping flow of the convecting mantle. The emerging scenarios on the global carbon cycle are finally discussed. [1] Boulard, E., et al., New host for carbon in the deep Earth. Proceedings of the National Academy of Sciences, 2011. 108(13): p. 5184-5187. [2] Walter, M.J., et al., Deep Mantle Cycling of Oceanic Crust: Evidence from Diamonds and Their Mineral Inclusions. Science, 2011. 334(6052): p. 54-57. [3] Morra, G., et al., Ascent of Bubbles in Magma Conduits Using Boundary Elements and Particles. Procedia Computer

  7. Effects of implementing the Simple Biosphere Model in a general circulation model

    NASA Technical Reports Server (NTRS)

    Sato, N.; Sellers, P. J.; Randall, D. A.; Schneider, E. K.; Shukla, J.

    1989-01-01

    The Simple Biosphere Model (SiB) of Sellers et al., was designed to simulate the interactions between the earth's land surface and the atmosphere by treating the vegetation explicitly and realistically, thereby incorporating the biophysical controls on the exchanges of radiation, momentum, sensible and latent heat between the two systems. This paper describes the steps taken to implement SiB in a modified version of the National Meteorological Center's global spectral general circulation model (GCM) and explores the impact of the implementation on the simulated land surface fluxes and near-surface meteorological conditions. The coupled model (SiB-GCM) was used to produce summer and winter simulations. The same GCM was used with a conventional hydrological model (Ctl-GCM) to produce comparable 'control' summer and winter simulations for comparison. It was found that SiB-GCM produced a more realistic partitioning of energy at the land surface than Ctl-GCM. Generally, SiB-GCM, produced more sensible heat flux and less latent heat flux over vegetated land than did Ctl-GCM and this resulted in a much deeper daytime planetary boundary layer and reduced precipitation rates over the continents in SiB-GCM. In the summer simulation, the 200 mb jet stream was slightly weakened in the SiB-GCM relative to the Ctl-GCM results and analyses made from observations.

  8. Accelerating advances in continental domain hydrologic modeling

    NASA Astrophysics Data System (ADS)

    Archfield, Stacey A.; Clark, Martyn; Arheimer, Berit; Hay, Lauren E.; McMillan, Hilary; Kiang, Julie E.; Seibert, Jan; Hakala, Kirsti; Bock, Andrew; Wagener, Thorsten; Farmer, William H.; Andréassian, Vazken; Attinger, Sabine; Viglione, Alberto; Knight, Rodney; Markstrom, Steven; Over, Thomas

    2015-12-01

    In the past, hydrologic modeling of surface water resources has mainly focused on simulating the hydrologic cycle at local to regional catchment modeling domains. There now exists a level of maturity among the catchment, global water security, and land surface modeling communities such that these communities are converging toward continental domain hydrologic models. This commentary, written from a catchment hydrology community perspective, provides a review of progress in each community toward this achievement, identifies common challenges the communities face, and details immediate and specific areas in which these communities can mutually benefit one another from the convergence of their research perspectives. Those include: (1) creating new incentives and infrastructure to report and share model inputs, outputs, and parameters in data services and open access, machine-independent formats for model replication or reanalysis; (2) ensuring that hydrologic models have: sufficient complexity to represent the dominant physical processes and adequate representation of anthropogenic impacts on the terrestrial water cycle, a process-based approach to model parameter estimation, and appropriate parameterizations to represent large-scale fluxes and scaling behavior; (3) maintaining a balance between model complexity and data availability as well as uncertainties; and (4) quantifying and communicating significant advancements toward these modeling goals.

  9. Accelerating advances in continental domain hydrologic modeling

    USGS Publications Warehouse

    Archfield, Stacey A.; Clark, Martyn; Arheimer, Berit; Hay, Lauren E.; McMillan, Hilary; Kiang, Julie E.; Seibert, Jan; Hakala, Kirsti; Bock, Andrew R.; Wagener, Thorsten; Farmer, William H.; Andreassian, Vazken; Attinger, Sabine; Viglione, Alberto; Knight, Rodney; Markstrom, Steven; Over, Thomas M.

    2015-01-01

    In the past, hydrologic modeling of surface water resources has mainly focused on simulating the hydrologic cycle at local to regional catchment modeling domains. There now exists a level of maturity among the catchment, global water security, and land surface modeling communities such that these communities are converging toward continental domain hydrologic models. This commentary, written from a catchment hydrology community perspective, provides a review of progress in each community toward this achievement, identifies common challenges the communities face, and details immediate and specific areas in which these communities can mutually benefit one another from the convergence of their research perspectives. Those include: (1) creating new incentives and infrastructure to report and share model inputs, outputs, and parameters in data services and open access, machine-independent formats for model replication or reanalysis; (2) ensuring that hydrologic models have: sufficient complexity to represent the dominant physical processes and adequate representation of anthropogenic impacts on the terrestrial water cycle, a process-based approach to model parameter estimation, and appropriate parameterizations to represent large-scale fluxes and scaling behavior; (3) maintaining a balance between model complexity and data availability as well as uncertainties; and (4) quantifying and communicating significant advancements toward these modeling goals.

  10. A Modeling Study of Hydrodynamic Circulation in a Fjord of the Pacific Northwest

    SciTech Connect

    Wang, Taiping; Yang, Zhaoqing

    2012-10-01

    Increased eutrophication and degraded water quality in estuarine and coastal waters have been a worldwide environmental concern. While it is commonly accepted that anthropogenic impact plays a major role in many emerging water quality issues, natural conditions such as restricted water circulations controlled by geometry may also substantially contribute to unfavorable water quality in certain ecosystems. To elucidate the contributions from different factors, a hydrodynamic-water quality model that integrates both physical transport and pollutant loadings is particularly warranted. A preliminary modeling study using the Environmental Fluid Dynamic Code (EFDC) is conducted to investigate hydrodynamic circulation and low dissolved oxygen (DO) in Hood Canal, a representative fjord in the U.S. Pacific Northwest. Because the water quality modeling work is still ongoing, this paper focuses on the progress in hydrodynamic modeling component. The hydrodynamic model has been set up using the publicly available forcing data and was calibrated against field observations or NOAA predictions for tidal elevation, current, salinity and temperature. The calibrated model was also used to estimate physical transport timescales such as residence time in the estuary. The preliminary model results demonstrate that the EFDC Hood Canal model is capable of capturing the general circulation patterns in Hood Canal, including weak tidal current and strong vertical stratification. The long residence time (i.e., on the order of 100 days for the entire estuary) also indicates that restricted water circulation could contribute to low DO in the estuary and also makes the system especially susceptible to anthropogenic disturbance, such as excess nutrient input.

  11. Global OH distribution derived from general circulation model fields of ozone and water vapor

    SciTech Connect

    Allam, R.J.; Groves, K.S.; Tuck, A.F.

    1981-06-20

    The variability of OH computed with a photochemical steady state model from general circulation model fields of ozone and water vapor is examined. Multivariate regression analysis is used to obtain values of parametric coefficients for the variables upon which the OH field principally depends, and conclusions are drawn about the longitudinal phase relations between these variables for various pressure levels. 21 references, 8 figures, 6 tables.

  12. A wind-driven circulation model of the Tyrrhenian Sea area

    NASA Astrophysics Data System (ADS)

    Pierini, S.; Simioli, A.

    1998-12-01

    The wind-driven component of the circulation in the Tyrrhenian Sea area was analyzed by means of a free-surface, barotropic primitive equation model implemented in the whole Mediterranean Sea. The `National Meteorological Center' (NMC) wind data covering the period 1980-1988 were used to force the model. Both the seasonal and the high frequency variability were studied. For the first case, a perpetual wind forcing was constructed by instantaneously averaging the wind stresses over the 9 years, and the response was Fourier filtered in order to get rid of the residual rapid fluctuations. The daily variability was then produced for the test years 1981 and 1987 by making use of the instantaneous forcing. The main features of the wind-driven climatological Tyrrhenian circulation known from data and general circulation modelling were found to be reproduced by this process model. The winter cyclonic circulation induced by the strong positive wind vorticity input evolved into a much weaker, partially reversed circulation in summer months. A mainly northward flux through the strait of Corsica and a horizontally sheared current in the strait of Sicily were found. The rapid fluctuations that the wind was able to induce in the ocean were then studied. The instantaneous currents were found to be up to 10 times larger than the corresponding climatological ones, with episodes of reversal over a period of few days. The experimental evidence of the existence of these rapid wind-driven fluctuations is discussed. The analysis of the daily variability provides a realistic picture of the character of the wind-driven circulation in the Tyrrhenian Sea that differs considerably from the classical seasonal dynamics. As an indicator of the Tyrrhenian Sea dynamics, the mass transport through the strait of Corsica was evaluated for the year 1987 and compared with available experimental data. As a result, the low-passed wind-driven transport reflects the seasonal trend and accounts for 15

  13. Advancements in predictive plasma formation modeling

    NASA Astrophysics Data System (ADS)

    Purvis, Michael A.; Schafgans, Alexander; Brown, Daniel J. W.; Fomenkov, Igor; Rafac, Rob; Brown, Josh; Tao, Yezheng; Rokitski, Slava; Abraham, Mathew; Vargas, Mike; Rich, Spencer; Taylor, Ted; Brandt, David; Pirati, Alberto; Fisher, Aaron; Scott, Howard; Koniges, Alice; Eder, David; Wilks, Scott; Link, Anthony; Langer, Steven

    2016-03-01

    We present highlights from plasma simulations performed in collaboration with Lawrence Livermore National Labs. This modeling is performed to advance the rate of learning about optimal EUV generation for laser produced plasmas and to provide insights where experimental results are not currently available. The goal is to identify key physical processes necessary for an accurate and predictive model capable of simulating a wide range of conditions. This modeling will help to drive source performance scaling in support of the EUV Lithography roadmap. The model simulates pre-pulse laser interaction with the tin droplet and follows the droplet expansion into the main pulse target zone. Next, the interaction of the expanded droplet with the main laser pulse is simulated. We demonstrate the predictive nature of the code and provide comparison with experimental results.

  14. Modeling of submarine melting in Petermann Fjord, Northwestern Greenland using an ocean general circulation model

    NASA Astrophysics Data System (ADS)

    Cai, C.; Rignot, E. J.; Xu, Y.; An, L.

    2013-12-01

    Basal melting of the floating tongue of Petermann Glacier, in northwestern Greenland is by far the largest process of mass ablation. Melting of the floating tongue is controlled by the buoyancy of the melt water plume, the pressure-dependence of the melting point of sea ice, and the mixing of warm subsurface water with fresh buoyant subglacial discharge. In prior simulations of this melting process, the role of subglacial discharge has been neglected because in similar configurations (floating ice shelves) in the Antarctic, surface runoff is negligible; this is however not true in Greenland. Here, we use the Mass Institute of Technology general circulation model (MITgcm) at a high spatial resolution (10 m x 10 m) to simulate the melting process of the ice shelf in 2-D. the model is constrained by ice shelf bathymetry and ice thickness from NASA Operation IceBridge, ocean temperature/salinity data from Johnson et al. (2011), and subglacial discharge estimated from output products of the Regional Atmospheric Climate Model (RACMO). We compare the results obtained in winter (no runoff) with summer, and the sensitivity of the results to thermal forcing from the ocean, and to the magnitude of subglacial runoff. We conclude on the impact of the ocean and surface melting on the melting regime of the floating ice tongue of Petermann. This work is performed under a contract with NASA Cryosphere Program.

  15. Modeling and analysis of aerosol processes in an interactive chemistry general circulation model

    NASA Astrophysics Data System (ADS)

    Verma, Sunita; Boucher, O.; Reddy, M. S.; Upadhyaya, H. C.; Le van, P.; Binkowski, F. S.; Sharma, O. P.

    2007-02-01

    An "online" aerosol dynamics and chemistry module is included in the Laboratoire de Météorologie Dynamique general circulation model (LMDZ), so that the chemical species are advected at each dynamical time step and evolve through chemical and physical processes that have been parameterized consistently with the meteorology. These processes include anthropogenic and biogenic emissions, over 50 gas/aqueous phase chemical reactions, transport due to advection, vertical diffusion and convection, dry deposition and wet scavenging. We have introduced a size-resolved representation of aerosols which undergo various processes such as coagulation, nucleation and dry and wet scavenging. The model considers 16 prognostic tracers: water vapor, liquid water, dimethyl sulfide (DMS), hydrogen sulfide (H2S), dimethyl sulphoxide (DMSO), methanesulphonic acid (MSA), sulfur dioxide (SO2), nitrogen oxides (NOX), carbon monoxide (CO), nitric acid (HNO3), ozone (O3), hydrogen peroxide (H2O2), sulfate mass and number for Aitken and accumulation modes. The scheme accounts for two-way interactions between tropospheric chemistry and aerosols. The oxidants and chemical species fields that represent the sulfate aerosol formation are evolved interactively with the model dynamics. A detailed description on the coupled climate-chemistry interactive module is presented with the evaluation of chemical species in winter and summer seasons. Aqueous phase reactions in cloud accounted for 71% of sulfate production rate, while only 45% of the sulfate burden in the troposphere is derived from in-cloud oxidation.

  16. Ross ice shelf cavity circulation, residence time, and melting: Results from a model of oceanic chlorofluorocarbons

    NASA Astrophysics Data System (ADS)

    Reddy, Tasha E.; Holland, David M.; Arrigo, Kevin R.

    2010-04-01

    Despite their harmful effects in the upper atmosphere, anthropogenic chlorofluorocarbons dissolved in seawater are extremely useful for studying ocean circulation and ventilation, particularly in remote locations. Because they behave as a passive tracer in seawater, and their atmospheric concentrations are well-mixed, well-known, and have changed over time, they are ideal for gaining insight into the oceanographic characteristics of the isolated cavities found under Antarctic ice shelves, where direct observations are difficult to obtain. Here we present results from a modeling study of air-sea chlorofluorocarbon exchange and ocean circulation in the Ross Sea, Antarctica. We compare our model estimates of oceanic CFC-12 concentrations along an ice shelf edge transect to field data collected during three cruises spanning 16 yr. Our model produces chlorofluorocarbon concentrations that are quite similar to those measured in the field, both in magnitude and distribution, showing high values near the surface, decreasing with depth, and increasing over time. After validating modeled circulation and air-sea gas exchange through comparison of modeled temperature, salinity, and chlorofluorocarbons with field data, we estimate that the residence time of water in the Ross Ice Shelf cavity is approximately 2.2 yr and that basal melt rates for the ice shelf average 10 cm yr -1. The model predicts a seasonal signature to basal melting, with highest melt rates in the spring and also the fall.

  17. Hydrodynamic model of advanced pressurized fluidized bed combustion

    SciTech Connect

    Horio, Masayuki; Lei, H.W.

    1997-12-31

    A hydrodynamic model was developed for the advanced pressurized fluidized bed combustion (A-PFBC) process. The particular system investigated here is composed of a pressurized circulating fluidized bed (PCFB) for coal gasification/desulfurization and a PCFB for combustion with the gas-solid counter-current flow through the two PCFBs. One of the most important parameters may be the material seal height (MSH) in the downcomer connecting the gasifier/desulfurizer and the combustor, which is thought to strongly influence the safe and stable operation of the process. In this mode, MSH was determined according to the pressure balance between the gasifier/desulfurizer and the combustor. The solid flux in the lower dense region of the two PCFBs was estimated by considering the clustering suspension and core-annulus flow. The mean cluster size and voidage in the cluster phase were predicted by the cluster size model of Horio-Ito (1996). Solid flux of the gasifier and combustor was calculated based on mass balances of limestone, char and ash in the system. Based on this model, the whole pressure profile loop in the system was predicted, and the effects of operating conditions on MSH between the gasifier and the combustor were investigated. The feasibility of the A-PCFB system with PCFBs both for the gasifier/desulfurizer and for the combustor was successfully confirmed.

  18. Advanced Small Modular Reactor Economics Model Development

    SciTech Connect

    Harrison, Thomas J.

    2014-10-01

    The US Department of Energy Office of Nuclear Energy’s Advanced Small Modular Reactor (SMR) research and development activities focus on four key areas: Developing assessment methods for evaluating advanced SMR technologies and characteristics; and Developing and testing of materials, fuels and fabrication techniques; and Resolving key regulatory issues identified by US Nuclear Regulatory Commission and industry; and Developing advanced instrumentation and controls and human-machine interfaces. This report focuses on development of assessment methods to evaluate advanced SMR technologies and characteristics. Specifically, this report describes the expansion and application of the economic modeling effort at Oak Ridge National Laboratory. Analysis of the current modeling methods shows that one of the primary concerns for the modeling effort is the handling of uncertainty in cost estimates. Monte Carlo–based methods are commonly used to handle uncertainty, especially when implemented by a stand-alone script within a program such as Python or MATLAB. However, a script-based model requires each potential user to have access to a compiler and an executable capable of handling the script. Making the model accessible to multiple independent analysts is best accomplished by implementing the model in a common computing tool such as Microsoft Excel. Excel is readily available and accessible to most system analysts, but it is not designed for straightforward implementation of a Monte Carlo–based method. Using a Monte Carlo algorithm requires in-spreadsheet scripting and statistical analyses or the use of add-ons such as Crystal Ball. An alternative method uses propagation of error calculations in the existing Excel-based system to estimate system cost uncertainty. This method has the advantage of using Microsoft Excel as is, but it requires the use of simplifying assumptions. These assumptions do not necessarily bring into question the analytical results. In fact, the

  19. Exploring the Venus global super-rotation using a comprehensive general circulation model

    NASA Astrophysics Data System (ADS)

    Mendonça, J. M.; Read, P. L.

    2016-12-01

    The atmospheric circulation in Venus is well known to exhibit strong super-rotation. However, the atmospheric mechanisms responsible for the formation of this super-rotation are still not fully understood. In this work, we developed a new Venus general circulation model to study the most likely mechanisms driving the atmosphere to the current observed circulation. Our model includes a new radiative transfer, convection and suitably adapted boundary layer schemes and a dynamical core that takes into account the dependence of the heat capacity at constant pressure with temperature. The new Venus model is able to simulate a super-rotation phenomenon in the cloud region quantitatively similar to the one observed. The mechanisms maintaining the strong winds in the cloud region were found in the model results to be a combination of zonal mean circulation, thermal tides and transient waves. In this process, the semi-diurnal tide excited in the upper clouds has a key contribution in transporting axial angular momentum mainly from the upper atmosphere towards the cloud region. The magnitude of the super-rotation in the cloud region is sensitive to various radiative parameters such as the amount of solar radiative energy absorbed by the surface, which controls the static stability near the surface. In this work, we also discuss the main difficulties in representing the flow below the cloud base in Venus atmospheric models. Our new radiative scheme is more suitable for 3D Venus climate models than those used in previous work due to its easy adaptability to different atmospheric conditions. This flexibility of the model was crucial to explore the uncertainties in the lower atmospheric conditions and may also be used in the future to explore, for example, dynamical-radiative-microphysical feedbacks.

  20. Impact of gefitinib in early stage treatment on circulating cytokines and lymphocytes for patients with advanced non-small cell lung cancer

    PubMed Central

    Sheng, Jin; Fang, Wenfeng; Liu, Xia; Xing, Shan; Zhan, Jianhua; Ma, Yuxiang; Huang, Yan; Zhou, Ningning; Zhao, Hongyun; Zhang, Li

    2017-01-01

    Objectives The impact of epidermal growth factor receptor (EGFR) tyrosine-kinase inhibitors (TKIs) on the human immune system remains undefined. This study illustrates the immunomodulatory effect of gefitinib in patients with advanced non-small cell lung cancer (NSCLC) and its relevant prognostic significance. Patients and methods Peripheral blood samples were collected from 54 patients at baseline and after 4 weeks of gefitinib treatment. Circulating lymphocyte populations and cytokine levels were measured. Pilot investigation of the impact of gefitinib on programmed cell death ligand-1 (PD-L1) expression was conducted by immunohistochemistry (IHC). Results and conclusion A significant increase of peripheral natural killer cells and interferon-gamma (INF-γ) after 4 weeks of gefitinib treatment (P=0.005 and 0.02, respectively). In addition, circulating interleukin (IL)-6 was significantly decreased, especially in patients sensitive to gefitinib (P<0.001). Higher levels of IL-6 at baseline independently correlated with poorer progression-free survival. Experiments with NSCLC specimens illustrated that PD-L1 expression were downregulated after 4 weeks of gefitinib treatment. In summary, it was found that gefitinib treatment can alter circulating cytokines and lymphocytes. Dynamic changes of circulating lymphocytes, cytokines, and even PD-L1 IHC expression around gefitinib treatment support the specific immunomodulatory effect of this agent for advanced NSCLC. PMID:28260924

  1. Calculation of a residual mean meridional circulation for a zonal-mean tracer transport model

    SciTech Connect

    Choi, W.K.; Rotman, D.A.; Wuebbles, D.J.

    1995-04-01

    Because of their computational advantages, zonally-averaged chemical-radiative-transport models are widely used to investigate the distribution of chemical species and their change due to the anthropogenic chemicals in the lower and middle atmosphere. In general, the Lagrangian-mean formulation would be ideal to treat transport due to the zonal mean circulation and eddies. However, the Lagrangian formulation is difficult to use in practical applications. The most widely-used formulation for treating global atmospheric dynamics in two-dimensional models is the transformed Eulerian mean (TEM) equations. The residual mean meridional circulation (RMMC) in the TEM system is used to advect tracers. In this study, the authors describe possible solution techniques for obtaining the RMMC in the LLNL two-dimensional chemical-radiative-transport model. In the first section, the formulation will be described. In sections 3 and 4, possible solution procedures will be described for a diagnostic and prognostic case, respectively.

  2. Modeling Black Sea circulation with high resolution in the coastal zone

    NASA Astrophysics Data System (ADS)

    Zalesnyi, V. B.; Gusev, A. V.; Agoshkov, V. I.

    2016-05-01

    We present a numerical model of Black Sea circulation based on primitive equations with improved spatial resolution in the coastal zone. The model equations are formulated in a two-pole orthogonal coordinate system with arbitrary locations of the poles and a vertical σ coordinate. Increased horizontal resolution is gained by displacing the pole into the vicinity of the separated subdomain. The problem is solved over a grid with a variable step. The northern coordinate pole is displaced to the vicinity of Gelendzhik; the grid step varies from 150 m in the coastal zone to 4.6 km in the main basin. We simulated the fields of currents, sea level, temperature, and salinity under the given atmospheric forcing in 2007. The model is capable of reproducing the large-scale Black Sea circulation and submesoscale variations in the coastal currents.

  3. Early warning signals of Atlantic Meridional Overturning Circulation collapse in a fully coupled climate model.

    PubMed

    Boulton, Chris A; Allison, Lesley C; Lenton, Timothy M

    2014-12-08

    The Atlantic Meridional Overturning Circulation (AMOC) exhibits two stable states in models of varying complexity. Shifts between alternative AMOC states are thought to have played a role in past abrupt climate changes, but the proximity of the climate system to a threshold for future AMOC collapse is unknown. Generic early warning signals of critical slowing down before AMOC collapse have been found in climate models of low and intermediate complexity. Here we show that early warning signals of AMOC collapse are present in a fully coupled atmosphere-ocean general circulation model, subject to a freshwater hosing experiment. The statistical significance of signals of increasing lag-1 autocorrelation and variance vary with latitude. They give up to 250 years warning before AMOC collapse, after ~550 years of monitoring. Future work is needed to clarify suggested dynamical mechanisms driving critical slowing down as the AMOC collapse is approached.

  4. Intraseasonal eddies in the Sulawesi Sea simulated in an ocean general circulation model

    NASA Astrophysics Data System (ADS)

    Masumoto, Y.; Kagimoto, T.; Yoshida, M.; Fukuda, M.; Hirose, N.; Yamagata, T.

    The intraseasonal variability associated with mesoscale eddies in the Sulawesi Sea simulated in a high resolution ocean general circulation model is described in detail. The cyclonic eddies, with a diameter of about 400 km, are generated at the entrance of the Sulawesi Sea between the Mindanao and the Halmahera Islands with 40 days interval. They are associated with a high speed (> 20 cm/s) down to 1000 m level. The anticlockwise circulation in the Sulawesi Sea, reported so far in both models and observations, may be a long time-averaged image of the above energetic eddies. The intraseasonal eddies significantly affect the volume transport through passages in the northern part of the Indonesian archipelago. The intraseasonal transport variation, however, is highly damped within the Indonesian seas in the present model.

  5. Aneuploidy of chromosome 8 in circulating tumor cells correlates with prognosis in patients with advanced gastric cancer

    PubMed Central

    Li, Yilin; Zhang, Xiaotian; Gong, Jifang; Zhang, Qiyue; Gao, Jing; Cao, Yanshuo; Wang, Daisy Dandan; Lin, Peter Ping; Shen, Lin

    2016-01-01

    Objective Previous work indicated that aneuploidy of chromosome 8 in circulating tumor cells (CTCs) correlated with therapeutic efficacy for advanced gastric cancer (AGC) patients. In this follow-up study performed on the same population of AGC patients, we investigated whether and how aneuploidy of chromosome 8 in CTCs correlates with patients’ clinical prognosis. Methods The prospective study was performed on 31 patients with newly diagnosed AGC. Previously established integrated subtraction enrichment (SE) and immunostaining-fluorescence in situ hybridization (iFISH) platform was applied to identify, enumerate and characterize CTCs. Quantification of CTCs and analysis of their aneuploidy of chromosome 8 were performed on patients before and after therapy. Results CTCs were measured in 93.5% of AGC patients, and two CTC subtypes with diverse threshold values were identified, multiploid CTCs with the threshold of ≥2 per 7.5 mL and multiploid plus triploid CTCs with the threshold of ≥4, which were found to significantly correlate with poor progression-free survival (PFS) and overall survival (OS). In particular, patients with ≥10% increased multiploid CTCs after an initial 6 weeks of therapy had poor PFS and OS, whereas improved PFS and OS were observed on those who had ≥10% decreased multiploid CTCs. After adjusting for clinically significant factors, ≥10% increased post-therapy multiploid CTCs was the only independent predictor of PFS and OS. Conclusions Aneuploidy of CTCs correlates with prognosis of AGC patients. Quantitative comparison monitoring multiploid CTCs before and after therapy may help predict improved or inferior prognosis and chemoresistance. PMID:28174486

  6. A simple-physics global circulation model for Venus: Sensitivity assessments of atmospheric superrotation

    NASA Astrophysics Data System (ADS)

    Hollingsworth, J. L.; Young, R. E.; Schubert, G.; Covey, C.; Grossman, A. S.

    2007-03-01

    A 3D global circulation model is adapted to the atmosphere of Venus to explore the nature of the planet's atmospheric superrotation. The model employs the full meteorological primitive equations and simplified forms for diabatic and other nonconservative forcings. It is therefore economical for performing very long simulations. To assess circulation equilibration and the occurrence of atmospheric superrotation, the climate model is run for 10,000-20,000 day integrations at 4° × 5° latitude-longitude horizontal resolution, and 56 vertical levels (denoted L56). The sensitivity of these simulations to imposed Venus-like diabatic heating rates, momentum dissipation rates, and various other key parameters (e.g., near-surface momentum drag), in addition to model configuration (e.g., low versus high vertical domain and number of atmospheric levels), is examined. We find equatorial superrotation in several of our numerical experiments, but the magnitude of superrotation is often less than observed. Further, the meridional structure of the mean zonal overturning (i.e., Hadley circulation) can consist of numerous cells which are symmetric about the equator and whose depth scale appears sensitive to the number of vertical layers imposed in the model atmosphere. We find that when realistic diabatic heating is imposed in the lowest several scales heights, only extremely weak atmospheric superrotation results.

  7. A computational model of the fetal circulation to quantify blood redistribution in intrauterine growth restriction.

    PubMed

    Garcia-Canadilla, Patricia; Rudenick, Paula A; Crispi, Fatima; Cruz-Lemini, Monica; Palau, Georgina; Camara, Oscar; Gratacos, Eduard; Bijnens, Bart H; Bijens, Bart H

    2014-06-01

    Intrauterine growth restriction (IUGR) due to placental insufficiency is associated with blood flow redistribution in order to maintain delivery of oxygenated blood to the brain. Given that, in the fetus the aortic isthmus (AoI) is a key arterial connection between the cerebral and placental circulations, quantifying AoI blood flow has been proposed to assess this brain sparing effect in clinical practice. While numerous clinical studies have studied this parameter, fundamental understanding of its determinant factors and its quantitative relation with other aspects of haemodynamic remodeling has been limited. Computational models of the cardiovascular circulation have been proposed for exactly this purpose since they allow both for studying the contributions from isolated parameters as well as estimating properties that cannot be directly assessed from clinical measurements. Therefore, a computational model of the fetal circulation was developed, including the key elements related to fetal blood redistribution and using measured cardiac outflow profiles to allow personalization. The model was first calibrated using patient-specific Doppler data from a healthy fetus. Next, in order to understand the contributions of the main parameters determining blood redistribution, AoI and middle cerebral artery (MCA) flow changes were studied by variation of cerebral and peripheral-placental resistances. Finally, to study how this affects an individual fetus, the model was fitted to three IUGR cases with different degrees of severity. In conclusion, the proposed computational model provides a good approximation to assess blood flow changes in the fetal circulation. The results support that while MCA flow is mainly determined by a fall in brain resistance, the AoI is influenced by a balance between increased peripheral-placental and decreased cerebral resistances. Personalizing the model allows for quantifying the balance between cerebral and peripheral-placental remodeling

  8. Studies in the parameterization of cloudiness in climate models and the analysis of radiation fields in general circulation models

    NASA Technical Reports Server (NTRS)

    HARSHVARDHAN

    1990-01-01

    Broad-band parameterizations for atmospheric radiative transfer were developed for clear and cloudy skies. These were in the shortwave and longwave regions of the spectrum. These models were compared with other models in an international effort called ICRCCM (Intercomparison of Radiation Codes for Climate Models). The radiation package developed was used for simulations of a General Circulation Model (GCM). A synopsis is provided of the research accomplishments in the two areas separately. Details are available in the published literature.

  9. Modeling of subaqueous melting in Petermann Fjord, Northwestern Greenland using an ocean general circulation model

    NASA Astrophysics Data System (ADS)

    Cai, C.; Rignot, E. J.; Xu, Y.; An, L.; Tinto, K. J.; van den Broeke, M. R.

    2014-12-01

    Basal melting of the floating tongue of Petermann Glacier, in northwestern Greenland is by far the largest process of mass ablation. Melting of the floating tongue is controlled by the buoyancy of the melt water plume, the pressure-dependence of the melting point of sea ice, and the mixing of warm subsurface water with fresh buoyant subglacial discharge. In prior simulations of this melting process, the role of subglacial discharge has been neglected because in similar configurations (floating ice shelves) in the Antarctic, surface runoff is negligible; this is however not true in Greenland. Here, we use the Mass Institute of Technology general circulation model (MITgcm) at a high spatial resolution (10 m x 10 m) to simulate the melting process of the ice shelf in 2-D. The model is constrained by ice shelf bathymetry and ice thickness (refined model in the immediate vicinity of the grounding line) from NASA Operation IceBridge (2011), ocean temperature/salinity data from Johnson et al. (2011), ocean tide height and current from the Arctic Ocean Tidal Inverse Model (AOTIM-5) by Padman and Erofeeva (2004) and subglacial discharge at the grounding line calculated by the hydrostatic potential of the ice from estimated products of the Regional Atmospheric Climate Model (RACMO) of Royal Netherlands Meteorological Institute (KNMI). We compare the results obtained in winter (no runoff) with summer, and the sensitivity of the results to thermal forcing from the ocean, and to the variation of tide height and current, and to the magnitude of subglacial runoff. We conclude on the impact of the ocean and surface melting on the melting regime of the floating ice tongue of Petermann. The basal melt rate increases ~20% with summer surface runoff. This work is performed under a contract with NASA Cryosphere Program.

  10. 76 FR 68011 - Medicare Program; Advanced Payment Model

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-02

    .../seamless-and-coordinated-care-models/advance-payment/ . FOR FURTHER INFORMATION CONTACT: Questions... provide high quality, coordinated care and generate cost savings. The Advance Payment Model will test....innovations.cms.gov/areas-of-focus/seamless-and-coordinated-care-models/advance-payment . II. Provisions...

  11. Circulation and effluent dilution modeling in Massachusetts Bay : model implementation, verification and results

    USGS Publications Warehouse

    Signell, Richard P.; Jenter, Harry L.; Blumberg, Alan F.

    1996-01-01

    A three-dimensional hydrodynamic model was developed as part of a cooperative U.S. Geological Survey/Massachusetts Water Resources Authority program to study contaminated sediment accumulation and transport in Massachusetts Bay. This report details the development of the model and assesses how well the model represents observed currents and water properties in the bay. It also summarizes circulation and comparative effluent dilution simulations from existing and future Boston sewage outfalls over a three-year period from October 1, 1989 to December 31, 1992. The ECOM-si model, a semi-implicit version of the Blumberg and Mellor (1987) Estuarine, Coastal and Ocean Model, is shown to reproduce many of the important hydrodynamical features of Massachusetts Bay: the seasonal evolution of the pycnocline, the mean flow pattern, and the strength of sub-tidal current fluctuations. Throughout the simulation period, during both vertically well-mixed and stratified conditions, the seasonal statistics of observed currents are well-represented by the model. The model is therefore appropriate for studying the average dilution of sewage effluent and other continuously discharged substances over seasonal time scales. The ability of the model to reproduce individual flow events varies with season and location within the bay. Flow events during unstratified conditions in western Massachusetts Bay are particularly well-represented, indicating that the model is appropriate for studying processes such as the transport of suspended material from the future outfall site due to winter storms. Individual flow events during stratified conditions and in the offshore Stellwagen Bank region, however, are less well-represented due to small length scales (caused by upwelling and river discharge events) coupled with insufficient data to specify open boundary forcing from the Gulf of Maine. Thus while the model might be used to answer issues such as the frequency with which Gulf of Maine river

  12. Two regimes of the Arctic's circulation from ocean models with ice and contaminants.

    PubMed

    Proshutinsky, A Y; Johnson, M

    2001-01-01

    A two-dimensional barotropic, coupled, ocean-ice model with a space resolution of 55.5 km and driven by atmospheric forces, river run-off, and sea-level slope between the Pacific and the Arctic Oceans, has been used to simulate the vertically averaged currents and ice drift in the Arctic Ocean. Results from 43 years of numerical simulations of water and ice motions demonstrate that two wind-driven circulation regimes are possible in the Arctic, a cyclonic and an anti-cyclonic circulation. These two regimes appear to alternate at 5-7 year intervals with the 10-15 year period. It is important to pollution studies to understand which circulation regime prevails at any time. It is anticipated that 1995 is a year with a cyclonic regime, and during this cyclonic phase and possibly during past cyclonic regimes as well, pollutants may reach the Alaskan shelf. The regime shifts demonstrated in this paper are fundamentally important to understanding the Arctic's general circulation and particularly important for estimating pollution transport.

  13. Assimilation of TOPEX/POSEIDON Altimeter Data into a Global Ocean Circulation Model: Are the Results Any Good?

    NASA Technical Reports Server (NTRS)

    Fukumori, I.; Fu, L. L.; Chao, Y.

    1998-01-01

    The feasibility of assimilating satellite altimetry data into a global ocean general ocean general circulation model is studied. Three years of TOPEX/POSEIDON data is analyzed using a global, three-dimensional, nonlinear primitive equation model.

  14. Rapid implementation of advanced constitutive models

    NASA Astrophysics Data System (ADS)

    Starman, Bojan; Halilovič, Miroslav; Vrh, Marko; Štok, Boris

    2013-12-01

    This paper presents a methodology based on the NICE integration scheme [1, 2] for simple and rapid numerical implementation of a class of plasticity constitutive models. In this regard, an algorithm is purposely developed for the implementation of newly developed advanced constitutive models into explicit finite element framework. The methodology follows the organization of the problem state variables into an extended form, which allows the constitutive models' equations to be organized in such a way, that the algorithm can be optionally extended with minimal effort to integrate also evolution equations related to a description of other specific phenomena, such as damage, distortional hardening, phase transitions, degradation etc. To confirm simplicity of the program implementation, computational robustness, effectiveness and improved accuracy of the implemented integration algorithm, a deep drawing simulation of the cylindrical cup is considered as the case study, performed in ABAQUS/Explicit. As a fairly complex considered model, the YLD2004-18p model [3, 4] is first implemented via external subroutine VUMAT. Further, to give additional proof of the simplicity of the proposed methodology, a combination of the YLD2004-18p model and Gurson-Tvergaard-Needleman model (GTN) is considered. As demonstrated, the implementation is really obtained in a very simple way.

  15. Modeling the periodic stratification and gravitational circulation in San Francisco Bay, California

    USGS Publications Warehouse

    Cheng, Ralph T.; Casulli, Vincenzo

    1996-01-01

    A high resolution, three-dimensional (3-D) hydrodynamic numerical model is applied to San Francisco Bay, California to simulate the periodic tidal stratification caused by tidal straining and stirring and their long-term effects on gravitational circulation. The numerical model is formulated using fixed levels in the vertical and uniform computational mesh on horizontal planes. The governing conservation equations, the 3-D shallow water equations, are solved by a semi-implicit finite-difference scheme. Numerical simulations for estuarine flows in San Francisco Bay have been performed to reproduce the hydrodynamic properties of tides, tidal and residual currents, and salt transport. All simulations were carried out to cover at least 30 days, so that the spring-neap variance in the model results could be analyzed. High grid resolution used in the model permits the use of a simple turbulence closure scheme which has been shown to be sufficient to reproduce the tidal cyclic stratification and well-mixed conditions in the water column. Low-pass filtered 3-D time-series reveals the classic estuarine gravitational circulation with a surface layer flowing down-estuary and an up-estuary flow near the bottom. The intensity of the gravitational circulation depends upon the amount of freshwater inflow, the degree of stratification, and spring-neap tidal variations.

  16. An analytical and experimental investigation of natural circulation transients in a model pressurized water reactor

    SciTech Connect

    Massoud, M

    1987-01-01

    Natural Circulation phenomena in a simulated PWR was investigated experimentally and analytically. The experimental investigation included determination of system characteristics as well as system response to the imposed transient under symmetric and asymmetric operations. System characteristics were used to obtain correlation for heat transfer coefficient in heat exchangers, system flow resistance, and system buoyancy heat. Asymmetric transients were imposed to study flow oscillation and possible instability. The analytical investigation encompassed development of mathematical model for single-phase, steady-state and transient natural circulation as well as modification of existing model for two-phase flow analysis of phenomena such as small break LOCA, high pressure coolant injection and pump coast down. The developed mathematical model for single-phase analysis was computer coded to simulate the imposed transients. The computer program, entitled ''Symmetric and Asymmetric Analysis of Single-Phase Flow (SAS),'' were employed to simulate the imposed transients. It closely emulated the system behavior throughout the transient and subsequent steady-state. Modifications for two-phase flow analysis included addition of models for once-through steam generator and electric heater rods. Both programs are faster than real time. Off-line, they can be used for prediction and training applications while on-line they serve for simulation and signal validation. The programs can also be used to determine the sensitivity of natural circulation behavior to variation of inputs such as secondary distribution and power transients.

  17. Stratospheric wind errors, initial states and forecast skill in the GLAS general circulation model

    NASA Technical Reports Server (NTRS)

    Tenenbaum, J.

    1983-01-01

    Relations between stratospheric wind errors, initial states and 500 mb skill are investigated using the GLAS general circulation model initialized with FGGE data. Erroneous stratospheric winds are seen in all current general circulation models, appearing also as weak shear above the subtropical jet and as cold polar stratospheres. In this study it is shown that the more anticyclonic large-scale flows are correlated with large forecast stratospheric winds. In addition, it is found that for North America the resulting errors are correlated with initial state jet stream accelerations while for East Asia the forecast winds are correlated with initial state jet strength. Using 500 mb skill scores over Europe at day 5 to measure forecast performance, it is found that both poor forecast skill and excessive stratospheric winds are correlated with more anticyclonic large-scale flows over North America. It is hypothesized that the resulting erroneous kinetic energy contributes to the poor forecast skill, and that the problem is caused by a failure in the modeling of the stratospheric energy cycle in current general circulation models independent of vertical resolution.

  18. Regional eddy vorticity transport and the equilibrium vorticity budgets of a numerical model ocean circulation

    NASA Technical Reports Server (NTRS)

    Harrison, D. E.; Holland, W. R.

    1981-01-01

    A mean vorticity budget analysis is presented of Holland's (1978) numerical ocean general circulation experiment. The stable budgets are compared with classical circulation theory to emphasize the ways in which the mesoscale motions of the model alter (or leave unaltered) classical vorticity balances. The basinwide meridional transports of vorticity by the mean flow and by the mesoscale flow in the mean are evaluated to establish the role(s) of the mesoscale in the larger scale equilibrium vorticity transports. The vorticity equation for this model fluid system is presented and the budget analysis method is described. Vorticity budgets over the selected regions and on a larger scale are given, and a summary of budget results is provided along with remarks about the utility of this type of analysis.

  19. Modelling Andes Uplift Impact on Atmospheric Circulation: Consequences for Neogene Faunal and Floral Evolution ?

    NASA Astrophysics Data System (ADS)

    Sepulchre, P.; Sloan, L. C.; Fluteau, F.

    2007-12-01

    Tectonics in South America is marked by the uplift of the Andes during the Cenozoic. The Andes are approximately 7000 km long, oriented north-south, with some peak elevations in excess of 6000 m. Such a topographic structure has potentially a strong impact on atmospheric circulation. Climate model studies have showed that the Andes, as a topographic barrier, influence eastern Pacific Ocean climate and also meridional moisture transport above the south American continent. However, most studies have been done at the regional scale, and no quantification of rainfall changes due to a lower topography has been done. Here we use the high resolution Atmospheric General Circulation Model LMDz4 to quantify the impact of the Andes topography on the rainfall regime over the whole South American continent. Interpreting sensitivity experiments, we discuss about the tectonics history from 55 Ma to present-day and how to apply this method for Neogene paleoclimate, in a different continental configuration.

  20. Modelling the circulation and deep water formation in the Labrador Sea: sensitivity to Nordic Sea exchange

    NASA Astrophysics Data System (ADS)

    Czeschel, L.; Böning, C. W.

    2003-04-01

    Using an eddy-permitting model of the North Atlantic Ocean (part of the FLAME hierarchy) we investigate the impact of variable freshwater fluxes on the circulation, deep convection and the mixing between the boundary currents and the interior of the Labrador Sea. In this study, we use different forcing functions at the northern boundary (70N) to simulate variable freshwater (heat) exchanges with the Nordic Seas. In contrast to restoring to a climatology in a sponge layer, model versions with a prescribed streamfunction in an open boundary formulation give a better agreement with observational estimates of the circulation in this area. Varying the strength of the streamfunction at the northern boundary leads to fluctuations in the transport of the western boundary currents (East/West Greenland Current and Labrador Current) and thus to different freshwater budgets in the Labrador Sea.

  1. Crystal balls into the future: are global circulation and water balance models ready?

    NASA Astrophysics Data System (ADS)

    Fekete, Balázs M.; Pisacane, Giovanna; Wisser, Dominik

    2016-10-01

    Variabilities and changes due to natural and anthropogenic causes in the water cycle always presented a challenge for water management planning. Practitioners traditionally coped with variabilities in the hydrological processes by assuming stationarity in the probability distributions and attempted to address non-stationarity by revising this probabilistic properties via continued hydro-climatological observations. Recently, this practice was questioned and more reliance on Global Circulation Models was put forward as an alternative for water management plannig. This paper takes a brief assessment of the state of Global Circulation Models (GCM) and their applications by presenting case studies over Global, European and African domains accompanied by literature examples. Our paper demonstrates core deficiencies in GCM based water resources assessments and articulates the need for improved Earth system monitoring that is essential not only for water managers, but to aid the improvements of GCMs in the future.

  2. Interdecadal variations of the thermohaline circulation in a coupled ocean-atmosphere model

    SciTech Connect

    Delworth, T.; Manabe, S.; Stouffer, R.J. )

    1993-11-01

    A fully coupled ocean-atmosphere model is shown to have irregular oscillations of the thermohaline circulation in the NOrth Atlantic Ocean with a time scale of approximately 50 years. The irregular oscillation appears to be driven by density anomalies in the sinking region of the thermohaline circulation (approximately 52[degrees]N to 72[degrees]N) combined with much smaller density anomalies of opposite sign in the broad, rising region. The spatial pattern of sea surface temperature anomalies associated with this irregular oscillation bears an encouraging resemblance to a pattern of observed interdecadal variability in the North Atlantic. The anomalies of sea surface temperature induce model surface air temperature anomalies over the northern North Atlantic, Arctic, and northwestern Europe. 21 refs., 28 figs.

  3. Verification of the isotopic composition of precipitation simulated by a regional isotope circulation model over Japan.

    PubMed

    Tanoue, Masahiro; Ichiyanagi, Kimpei; Yoshimura, Kei

    2016-01-01

    The isotopic composition (δ(18)O and δ(2)H) of precipitation simulated by a regional isotope circulation model with a horizontal resolution of 10, 30 and 50 km was compared with observations at 56 sites over Japan in 2013. All simulations produced reasonable spatio-temporal variations in δ(18)O in precipitation over Japan, except in January. In January, simulated δ(18)O values in precipitation were higher than observed values on the Pacific side of Japan, especially during an explosively developing extratropical cyclone event. This caused a parameterisation of precipitation formulation about the large fraction of precipitated water to liquid detrained water in the lower troposphere. As a result, most water vapour that transported from the Sea of Japan precipitated on the Sea of Japan side. The isotopic composition of precipitation was a useful verification tool for the parameterisation of precipitation formulation as well as large-scale moisture transport processes in the regional isotope circulation model.

  4. AFDM: An Advanced Fluid-Dynamics Model

    SciTech Connect

    Wilhelm, D.

    1990-09-01

    This volume describes the Advanced Fluid-Dynamics Model (AFDM) for topologies, flow regimes, and interfacial areas. The objective of these models is to provide values for the interfacial areas between all components existing in a computational cell. The interfacial areas are then used to evaluate the mass, energy, and momentum transfer between the components. A new approach has been undertaken in the development of a model to convect the interfacial areas of the discontinuous velocity fields in the three-velocity-field environment of AFDM. These interfacial areas are called convectible surface areas. The continuous and discontinuous components are chosen using volume fraction and levitation criteria. This establishes so-called topologies for which the convectible surface areas can be determined. These areas are functions of space and time. Solid particulates that are limited to being discontinuous within the bulk fluid are assumed to have a constant size. The convectible surface areas are subdivided to model contacts between two discontinuous components or discontinuous components and the structure. The models have been written for the flow inside of large pools. Therefore, the structure is tracked only as a boundary to the fluid volume without having a direct influence on velocity or volume fraction distribution by means of flow regimes or boundary layer models. 17 refs., 7 tabs., 18 figs.

  5. Characterizing the surface circulation in the Ebro Delta using a HF radar data-model approach

    NASA Astrophysics Data System (ADS)

    Lorente Jimenez, Pablo; Piedracoba Varela, Silvia; Soto-Navarro, Javier; Garcia-Sotillo, Marcos; Alvarez Fanjul, Enrique

    2016-04-01

    One year-long (2014) quality-controlled current observations from a CODAR SeaSonde High Frequency (HF) radar network deployed in the Ebro Delta (northwestern Mediterranean) were combined with operational products provided by a regional ocean forecasting system named IBI (Iberia-Biscay-Ireland) in order to comprehensively portray the ocean state and its variability. First, accurate HF radar data were used as benchmark for the rigorous validation of IBI performance by means of the computation of skill metrics and quality indicators. The analysis of the monthly averaged current maps for 2014 showed that IBI properly captured the prevailing dynamic features of the coastal circulation observed by the HF radar, according to the resemblance of circulation patterns and the eddy kinetic energy spatial distribution. The model skill assessment was completed with an exploration of dominant modes of variability both in time and space. The EOF analysis confirmed that the modeled surface current field evolved in space and time according to three significantly dominant modes of variability which accounted for the 49.2% of the total variance, in close agreement with the results obtained for the HF radar (46.1%). The response of the subtidal surface current field to prevalent wind regimes in the study area was examined in terms of induced circulation structures by performing a conditional averaging approach. This data-model synergistic approach has proved to be valid to operationally monitor and describe the complex coastal circulation in Ebro Delta despite the observed model drawbacks in terms of reduced energy content in surface currents and some inaccuracies in the wind-driven low frequency response. This integrated methodology constitutes a powerful tool for improving operational ocean forecasting systems at European level within the frame of the Copernicus Marine Environment Monitoring Service (CMEMS). It also facilitates high-stakes decision-making for coastal management and

  6. Use of Ocean Remote Sensing Data to Enhance Predictions with a Coupled General Circulation Model

    NASA Technical Reports Server (NTRS)

    Rienecker, Michele M.

    1999-01-01

    Surface height, sea surface temperature and surface wind observations from satellites have given a detailed time sequence of the initiation and evolution of the 1997/98 El Nino. The data have beet complementary to the subsurface TAO moored data in their spatial resolution and extent. The impact of satellite observations on seasonal prediction in the tropical Pacific using a coupled ocean-atmosphere general circulation model will be presented.

  7. Derivation of revised formulae for eddy viscous forces used in the ocean general circulation model

    NASA Technical Reports Server (NTRS)

    Chou, Ru Ling

    1988-01-01

    Presented is a re-derivation of the eddy viscous dissipation tensor commonly used in present oceanographic general circulation models. When isotropy is imposed, the currently-used form of the tensor fails to return to the laplacian operator. In this paper, the source of this error is identified in a consistent derivation of the tensor in both rectangular and earth spherical coordinates, and the correct form of the eddy viscous tensor is presented.

  8. Characterizing the surface circulation in Ebro Delta (NW Mediterranean) with HF radar and modeled current data

    NASA Astrophysics Data System (ADS)

    Lorente, P.; Piedracoba, S.; Sotillo, M. G.; Aznar, R.; Amo-Balandron, A.; Pascual, A.; Soto-Navarro, J.; Alvarez-Fanjul, E.

    2016-11-01

    Quality-controlled current observations from a High Frequency radar (HFR) network deployed in the Ebro River Delta (NW Mediterranean) were combined with outputs from IBI operational ocean forecasting system in order to comprehensively portray the ocean state and its variability during 2014. Accurate HFR data were used as benchmark for a rigorous validation of the Iberia-Biscay-Ireland (IBI) regional system, routinely operated in the frame of the Copernicus Marine Environment Monitoring Service (CMEMS). The analysis of skill metrics and monthly averaged current maps showed that IBI reasonably captured the prevailing dynamic features of the coastal circulation previously observed by the HFR, according to the moderate resemblance found in circulation patterns and the spatial distribution of eddy kinetic energy. The model skill assessment was completed with an exploration of dominant modes of spatiotemporal variability. The EOF analysis confirmed that the modeled surface current field evolved both in space and time according to three significantly dominant modes of variability which accounted for the 49.2% of the total variance, in close agreement with the results obtained for HFR (46.1%). The response of the subtidal surface current field to prevailing wind regime in the study area was examined in terms of induced circulation structures and immediacy of reaction by performing a conditional averaging approach and a time-lagged vector correlation analysis, respectively. This observations-model synergistic strategy has proved to be valid to operationally monitor the complex coastal circulation in Ebro Delta despite the observed model drawbacks in terms of reduced energy content in surface currents and some inaccuracies in the wind-driven low frequency response. This integrated methodology aids to improve the prognostic capabilities of IBI ocean forecasting system and also to facilitate high-stakes decision-making for coastal management in the Ebro River Delta marine

  9. MODELING STRATEGIES TO COMPUTE NATURAL CIRCULATION USING CFD IN A VHTR AFTER A LOFA

    SciTech Connect

    Yu-Hsin Tung; Richard W. Johnson; Ching-Chang Chieng; Yuh-Ming Ferng

    2012-11-01

    A prismatic gas-cooled very high temperature reactor (VHTR) is being developed under the next generation nuclear plant program (NGNP) of the U.S. Department of Energy, Office of Nuclear Energy. In the design of the prismatic VHTR, hexagonal shaped graphite blocks are drilled to allow insertion of fuel pins, made of compacted TRISO fuel particles, and coolant channels for the helium coolant. One of the concerns for the reactor design is the effects of a loss of flow accident (LOFA) where the coolant circulators are lost for some reason, causing a loss of forced coolant flow through the core. In such an event, it is desired to know what happens to the (reduced) heat still being generated in the core and if it represents a problem for the fuel compacts, the graphite core or the reactor vessel (RV) walls. One of the mechanisms for the transport of heat out of the core is by the natural circulation of the coolant, which is still present. That is, how much heat may be transported by natural circulation through the core and upwards to the top of the upper plenum? It is beyond current capability for a computational fluid dynamic (CFD) analysis to perform a calculation on the whole RV with a sufficiently refined mesh to examine the full potential of natural circulation in the vessel. The present paper reports the investigation of several strategies to model the flow and heat transfer in the RV. It is found that it is necessary to employ representative geometries of the core to estimate the heat transfer. However, by taking advantage of global and local symmetries, a detailed estimate of the strength of the resulting natural circulation and the level of heat transfer to the top of the upper plenum is obtained.

  10. Prospects for Advanced RF Theory and Modeling

    SciTech Connect

    Batchelor, D.B.

    1999-04-12

    This paper represents an attempt to express in print the contents of a rather philosophical review talk. The charge for the talk was not to summarize the present status of the field and what we can do, but to assess what we will need to do in the future and where the gaps are in fulfilling these needs. The objective was to be complete, covering all aspects of theory and modeling in all frequency regimes, although in the end the talk mainly focussed on the ion cyclotron range of frequencies (ICRF). In choosing which areas to develop, it is important to keep in mind who the customers for RF modeling are likely to be and what sorts of tasks they will need for RF to do. This occupies the first part of the paper. Then we examine each of the elements of a complete RF theory and try to identify the kinds of advances needed.

  11. Prospects for advanced RF theory and modeling

    NASA Astrophysics Data System (ADS)

    Batchelor, D. B.

    1999-09-01

    This paper represents an attempt to express in print the contents of a rather philosophical review talk. The charge for the talk was not to summarize the present status of the field and what we can do, but to assess what we will need to do in the future and where the gaps are in fulfilling these needs. The objective was to be complete, covering all aspects of theory and modeling in all frequency regimes, although in the end the talk mainly focussed on the ion cyclotron range of frequencies (ICRF). In choosing which areas to develop, it is important to keep in mind who the customers for RF modeling are likely to be and what sorts of tasks they will need for RF to do. This occupies the first part of the paper. Then we examine each of the elements of a complete RF theory and try to identify the kinds of advances needed.

  12. Advanced modeling of prompt fission neutrons

    SciTech Connect

    Talou, Patrick

    2009-01-01

    Theoretical and numerical studies of prompt fission neutrons are presented. The main results of the Los Alamos model often used in nuclear data evaluation work are reviewed briefly, and a preliminary assessment of uncertainties associated with the evaluated prompt fission neutron spectrum for n (0.5 MeV)+{sup 239}Pu is discussed. Advanced modeling of prompt fission neutrons is done by Monte Carlo simulations of the evaporation process of the excited primary fission fragments. The successive emissions of neutrons are followed in the statistical formalism framework, and detailed information, beyond average quantities, can be inferred. This approach is applied to the following reactions: {sup 252}Cf (sf), n{sub th} + {sup 239}Pu, n (0.5 MeV)+{sup 235}U, and {sup 236}Pu (sf). A discussion on the merits and present limitations of this approach concludes this presentation.

  13. Sensitivity of northwestern North Atlantic shelf circulation to surface and boundary forcing: A regional model assessment

    NASA Astrophysics Data System (ADS)

    Brennan, Catherine E.; Bianucci, Laura; Fennel, Katja

    2014-05-01

    The northwestern North Atlantic shelf circulation, influenced by both North Atlantic subpolar and subtropical gyres, is one of the hydrographically most variable regions in the North Atlantic Ocean and hosts biologically rich and productive fishing grounds. With the goal of simulating conditions in this productive and complex region, we implemented a nested regional ocean model for the northwest North Atlantic shelves including the Gulf of Maine, the Scotian Shelf, the Gulf of St. Lawrence, the Grand Banks, and the adjacent deep ocean. Configuring such a model requires choosing external data to supply surface forcing and initial and boundary conditions, as well as the consideration of nesting options. Although these selections can greatly affect model performance and results, often they are not systematically investigated. Here we assessed the sensitivity of our regional model to a suite of atmospheric forcing datasets, to sets of initial and boundary conditions constructed from multiple global ocean models and a larger scale regional ocean model, and to two variants of the model grid - one extending further off-shelf and resolving Flemish Cap topography. We conducted model simulations for a 6-year period and assessed model performance relative to a regional climatological dataset of temperature and salinity, observations collected from multiple monitoring stations and cruise transect lines, satellite sea surface temperature (SST) data, and descriptions of regional currents from literature. Based on this model assessment, we determined the model configuration that best reproduces observations. We find that while all surface forcing datasets are capable of producing model SST close to observed, the different datasets result in significant differences in model sea surface salinity (SSS). We find that initial and boundary conditions based on global ocean models do not necessary produce realistic circulation, and climatological initial and boundary conditions can

  14. Modeling the Effects of Anisotropic Turbulence and Dispersive Waves on Oceanic Circulation and their Incorporation in Navy Ocean Models

    DTIC Science & Technology

    2011-09-30

    anisotropic turbulence and dispersive waves in different environments , test them, compare them with data and implement them in ocean models. In this project...stratification and/or a solid body rotation. We have also performed computer simulations with an idealized circulation model of quasi-two-dimensional...member of a team on Martian planetary boundary layer at the International Space Science Institute and was responsible for reviewing turbulence models

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

    USGS Publications Warehouse

    McKenna, J.E.; 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. Global QBO in circulation and ozone. Part 2: A simple mechanistic model

    SciTech Connect

    Tung, K.K.; Yang, H.

    1994-10-01

    Although the phenomenon of equatorial quasi-biennial oscillation is relatively well understood, the problem of how the equatorially confined quasi-biennial oscillation (QBO) wave forcing can induce a signal in the extratropics of comparable or larger magnitude remains unsolved. A simple mechanistic model is constructed to provide a quantitative test of the hypothesis that the phenomenon of extratropical QBO is mainly caused by an anomalous seasonal circulation induced by an anomalous Eliassen-Palm (E-P) flux divergence. The anomaly in E-P flux divergence may be caused in turn by the relative poleward and downward shift of the region of irreversible mixing (breaking) of the extratropical planetary waves during the easterly phase of the equatorial QBO as compared to its westerly phase. The hemispheric nature of the anomaly wave forcing in solstice seasons (viz., no wave breaking in the summer hemisphere) induces a global circulation anomaly that projects predominantly into the first few zonal Hough modes of Plumb. Such a global QBO circulation pattern, although difficult to measure directly, is reflected in the distribution of stratospheric tracers transported by it. Our model produces a global pattern of QBO anomaly in column ozone that appears to account for much of the unfiltered interannual variability in the column ozone observed by the total ozone mapping spectrometer (TOMS) instrument aboard the Nimbus satellite. Furthermore, the model produces the characteristic spectrum of the observation with peaks at periods of 20 and 30 months.

  17. Ocean circulation model predicts high genetic structure observed in a long-lived pelagic developer.

    PubMed

    Sunday, J M; Popovic, I; Palen, W J; Foreman, M G G; Hart, M W

    2014-10-01

    Understanding the movement of genes and individuals across marine seascapes is a long-standing challenge in marine ecology and can inform our understanding of local adaptation, the persistence and movement of populations, and the spatial scale of effective management. Patterns of gene flow in the ocean are often inferred based on population genetic analyses coupled with knowledge of species' dispersive life histories. However, genetic structure is the result of time-integrated processes and may not capture present-day connectivity between populations. Here, we use a high-resolution oceanographic circulation model to predict larval dispersal along the complex coastline of western Canada that includes the transition between two well-studied zoogeographic provinces. We simulate dispersal in a benthic sea star with a 6-10 week pelagic larval phase and test predictions of this model against previously observed genetic structure including a strong phylogeographic break within the zoogeographical transition zone. We also test predictions with new genetic sampling in a site within the phylogeographic break. We find that the coupled genetic and circulation model predicts the high degree of genetic structure observed in this species, despite its long pelagic duration. High genetic structure on this complex coastline can thus be explained through ocean circulation patterns, which tend to retain passive larvae within 20-50 km of their parents, suggesting a necessity for close-knit design of Marine Protected Area networks.

  18. A zonally symmetric model for the monsoon-Hadley circulation with stochastic convective forcing

    NASA Astrophysics Data System (ADS)

    De La Chevrotière, Michèle; Khouider, Boualem

    2017-02-01

    Idealized models of reduced complexity are important tools to understand key processes underlying a complex system. In climate science in particular, they are important for helping the community improve our ability to predict the effect of climate change on the earth system. Climate models are large computer codes based on the discretization of the fluid dynamics equations on grids of horizontal resolution in the order of 100 km, whereas unresolved processes are handled by subgrid models. For instance, simple models are routinely used to help understand the interactions between small-scale processes due to atmospheric moist convection and large-scale circulation patterns. Here, a zonally symmetric model for the monsoon circulation is presented and solved numerically. The model is based on the Galerkin projection of the primitive equations of atmospheric synoptic dynamics onto the first modes of vertical structure to represent free tropospheric circulation and is coupled to a bulk atmospheric boundary layer (ABL) model. The model carries bulk equations for water vapor in both the free troposphere and the ABL, while the processes of convection and precipitation are represented through a stochastic model for clouds. The model equations are coupled through advective nonlinearities, and the resulting system is not conservative and not necessarily hyperbolic. This makes the design of a numerical method for the solution of this system particularly difficult. Here, we develop a numerical scheme based on the operator time-splitting strategy, which decomposes the system into three pieces: a conservative part and two purely advective parts, each of which is solved iteratively using an appropriate method. The conservative system is solved via a central scheme, which does not require hyperbolicity since it avoids the Riemann problem by design. One of the advective parts is a hyperbolic diagonal matrix, which is easily handled by classical methods for hyperbolic equations, while

  19. A zonally symmetric model for the monsoon-Hadley circulation with stochastic convective forcing

    NASA Astrophysics Data System (ADS)

    De La Chevrotière, Michèle; Khouider, Boualem

    2016-09-01

    Idealized models of reduced complexity are important tools to understand key processes underlying a complex system. In climate science in particular, they are important for helping the community improve our ability to predict the effect of climate change on the earth system. Climate models are large computer codes based on the discretization of the fluid dynamics equations on grids of horizontal resolution in the order of 100 km, whereas unresolved processes are handled by subgrid models. For instance, simple models are routinely used to help understand the interactions between small-scale processes due to atmospheric moist convection and large-scale circulation patterns. Here, a zonally symmetric model for the monsoon circulation is presented and solved numerically. The model is based on the Galerkin projection of the primitive equations of atmospheric synoptic dynamics onto the first modes of vertical structure to represent free tropospheric circulation and is coupled to a bulk atmospheric boundary layer (ABL) model. The model carries bulk equations for water vapor in both the free troposphere and the ABL, while the processes of convection and precipitation are represented through a stochastic model for clouds. The model equations are coupled through advective nonlinearities, and the resulting system is not conservative and not necessarily hyperbolic. This makes the design of a numerical method for the solution of this system particularly difficult. Here, we develop a numerical scheme based on the operator time-splitting strategy, which decomposes the system into three pieces: a conservative part and two purely advective parts, each of which is solved iteratively using an appropriate method. The conservative system is solved via a central scheme, which does not require hyperbolicity since it avoids the Riemann problem by design. One of the advective parts is a hyperbolic diagonal matrix, which is easily handled by classical methods for hyperbolic equations, while

  20. Advancing an Information Model for Environmental Observations

    NASA Astrophysics Data System (ADS)

    Horsburgh, J. S.; Aufdenkampe, A. K.; Hooper, R. P.; Lehnert, K. A.; Schreuders, K.; Tarboton, D. G.; Valentine, D. W.; Zaslavsky, I.

    2011-12-01

    have been modified to support data management for the Critical Zone Observatories (CZOs). This paper will present limitations of the existing information model used by the CUAHSI HIS that have been uncovered through its deployment and use, as well as new advances to the information model, including: better representation of both in situ observations from field sensors and observations derived from environmental samples, extensibility in attributes used to describe observations, and observation provenance. These advances have been developed by the HIS team and the broader scientific community and will enable the information model to accommodate and better describe wider classes of environmental observations and to better meet the needs of the hydrologic science and CZO communities.

  1. Circulating tumor cells from patients with advanced prostate and breast cancer display both epithelial and mesenchymal markers.

    PubMed

    Armstrong, Andrew J; Marengo, Matthew S; Oltean, Sebastian; Kemeny, Gabor; Bitting, Rhonda L; Turnbull, James D; Herold, Christina I; Marcom, Paul K; George, Daniel J; Garcia-Blanco, Mariano A

    2011-08-01

    During cancer progression, malignant cells undergo epithelial-mesenchymal transitions (EMT) and mesenchymal-epithelial transitions (MET) as part of a broad invasion and metastasis program. We previously observed MET events among lung metastases in a preclinical model of prostate adenocarcinoma that suggested a relationship between epithelial plasticity and metastatic spread. We thus sought to translate these findings into clinical evidence by examining the existence of EMT in circulating tumor cells (CTC) from patients with progressive metastatic solid tumors, with a focus on men with castration-resistant prostate cancer (CRPC) and women with metastatic breast cancer. We showed that the majority (> 80%) of these CTCs in patients with metastatic CRPC coexpress epithelial proteins such as epithelial cell adhesion molecule (EpCAM), cytokeratins (CK), and E-cadherin, with mesenchymal proteins including vimentin, N-cadherin and O-cadherin, and the stem cell marker CD133. Equally, we found that more than 75% of CTCs from women with metastatic breast cancer coexpress CK, vimentin, and N-cadherin. The existence and high frequency of these CTCs coexpressing epithelial, mesenchymal, and stem cell markers in patients with progressive metastases has important implications for the application and interpretation of approved methods to detect CTCs.

  2. a General Circulation Model Investigation of the Atmospheric Response to EL Nino

    NASA Astrophysics Data System (ADS)

    de Aragao, Jose Oribe Rocha

    The observed atmospheric response to sea surface temperature (SST) anomalies associated with El Nino episodes is simulated with the use of a general circulation model (GCM) of the atmosphere. A series of experiments has been performed with the Rasmusson and Carpenter six-episode (El Nino) composite SST anomaly (SSTA) in the tropical Pacific superimposed upon the prescribed climatological SST (CSST). Five independent 400-day runs were made beginning in April of the El Nino year (Year 0) and ending in May of the year after the maximum SSTA in the tropical Pacific (Year +1). Each of the integrations started from different initial conditions selected from different years in a 20 -year control run. The five-year El Nino integration was compared with the control run by analyzing the ensemble monthly, seasonal and annual mean statistics. The model's tropical response resembles the anomalous features found in previous studies. Some features are expected from the constraint imposed by the vorticity balance in the linear theory. For example, the upper level anticyclone pair and the lower level cyclonic circulation centers in the central Pacific are present for almost all months. These responses are significant and seem to be related to the location of both the maximum in CSST and the maximum in SSTA. An anomalous Walker Circulation is found in the vertical plane along the equatorial region. Rainfall departures from the long-term mean are associated with the anomalous Walker Circulation. An analysis of rainfall data over Northeast Brazil reveals sup- pressed rainfall in this area during the rainy season of Year(+1). Significant lower-than-normal rainfall is also found in the model's response during that period. This reduction in precipitation is associated with the downward branch of the anomalous Walker Circulation. The model's extratropical response is weaker than the tropical response and is not well organized. A Pacific/North American (PNA) pattern is present during the

  3. Decadal Variations of the Atlantic Meridional Overturning Circulation as simulated by the VIKING20 Model

    NASA Astrophysics Data System (ADS)

    Handmann, Patricia; Fischer, Jürgen; Visbeck, Martin; Behrens, Erik; Patara, Lavinia

    2015-04-01

    Time series of observed deep circulation transports and water mass properties in the subpolar North Atlantic are beginning to be long enough to investigate multiannual to decadal variability of the deep water. At the same time high resolution ocean circulation models (1/20° resolution VIKING20 model) can be used to compare observations with model simulation. The models also allow to diagnose the deep water circulation processes more completely and to relate local to basin scale signals. North Atlantic Deep Water (NADW) is a complex combination of water masses from different origins and pathways that meet at the exit of the Labrador Sea. The lower part of NADW is formed by water masses entering the subpolar basin over the Greenland-Scotland ridge. Iceland-Scotland Overflow Water (ISOW) from the eastern sills has the longest pathway and joins the densest deep water component from Denmark Strait (DSOW) after crossing the Mid-Atlantic-Ridge through Charlie-Gibbs Fracture Zone (CGFZ); together, they form the Lower NADW. The upper component of the NADW is composed of Labrador Sea Water (LSW), which is formed and modified through deep convection in the Labrador Sea. Using 60 year long time series of North Atlantic water masses and currents produced by the Viking20 model driven by observed monthly winds, a comparison of transport variability of observed and modeled data will be presented at three locations: Deep flow at the exit of the Labrador Sea at 53°N; upper layer transports between New Jersey and Bermuda (OLEANDER section) and between the southern tip of Greenland and Portugal (OVIDE section). Is the model reproducing the observed long-term behavior of the different components in phase and amplitude? Do the results permit identification of the processes leading to these variations in transport variability? Finally, is it possible to extend the observed variability pattern over the observed time span (15 years) to the total time range of the model simulations (60

  4. A zonally averaged, three-basin ocean circulation model for climate studies

    SciTech Connect

    Hovine, S.; Fichefet, T.

    1994-09-01

    A two-dimensional, three-basin ocean model suitable for long-term climate studies is developed. The model is based on the zonally averaged form of the primitive equations written in spherical coordinates. The east-west density difference which arises upon averaging the momentum equations is taken to be proportional to the meridional density gradient. Lateral exchanges of heat and salt between the basins are explicitly resolved. Moreover, the model includes bottom topography and has representations of the Arctic Ocean and of the Weddell and Ross seas. Under realistic restoring boundary conditions, the model reproduces the global conveyor belt: deep water is formed in the Atlantic between 60 and 70{degree}N at a rate of about 17 Sv (1 Sv=10{sup 6} m{sup 3}S{sup {minus}1}) and in the vicinity of the Antarctic continent, while the Indian and Pacific basins show broad upwelling. Superimposed on this thermohaline circulation are vigorous wind-driven cells in the upper thermocline. The simulated temperature and salinity fields and the computed meridional heat transport compare reasonably well with the observational estimates. When mixed boundary conditions i.e., a restoring condition no sea-surface temperature and flux condition on sea-surface salinity are applied, the model exhibits an irregular behavior before reaching a steady state characterized by self-sustained oscillations of 8.5-y period. The conveyor-belt circulation always results at this stage. A series of perturbation experiments illustrates the ability of the model to reproduce different steady-state circulations under mixed boundary conditions. Finally, the model sensitivity to various factors is examined. This sensitivity study reveals that the bottom topography and the presence of a submarine meridional ridge in the zone of the Drake passage play a crucial role in determining the properties of the model bottom-water masses. The importance of the seasonality of the surface forcing is also stressed.

  5. Vertical heat flux in the ocean: Estimates from observations and from a coupled general circulation model

    NASA Astrophysics Data System (ADS)

    Cummins, Patrick F.; Masson, Diane; Saenko, Oleg A.

    2016-06-01

    The net heat uptake by the ocean in a changing climate involves small imbalances between the advective and diffusive processes that transport heat vertically. Generally, it is necessary to rely on global climate models to study these processes in detail. In the present study, it is shown that a key component of the vertical heat flux, namely that associated with the large-scale mean vertical circulation, can be diagnosed over extra-tropical regions from global observational data sets. This component is estimated based on the vertical velocity obtained from the geostrophic vorticity balance, combined with estimates of absolute geostrophic flow. Results are compared with the output of a non-eddy resolving, coupled atmosphere-ocean general circulation model. Reasonable agreement is found in the latitudinal distribution of the vertical heat flux, as well as in the area-integrated flux below about 250 m depth. The correspondence with the coupled model deteriorates sharply at depths shallower than 250 m due to the omission of equatorial regions from the calculation. The vertical heat flux due to the mean circulation is found to be dominated globally by the downward contribution from the Southern Hemisphere, in particular the Southern Ocean. This is driven by the Ekman vertical velocity which induces an upward transport of seawater that is cold relative to the horizontal average at a given depth. The results indicate that the dominant characteristics of the vertical transport of heat due to the mean circulation can be inferred from simple linear vorticity dynamics over much of the ocean.

  6. On the tidally driven circulation in the South China Sea: modeling and analysis

    NASA Astrophysics Data System (ADS)

    Nelko, Varjola; Saha, Abhishek; Chua, Vivien P.

    2014-03-01

    The South China Sea is a large marginal sea surrounded by land masses and island chains, and characterized by complex bathymetry and irregular coastlines. An unstructured-grid SUNTANS model is employed to perform depth-averaged simulations of the circulation in the South China Sea. The model is tidally forced at the open ocean boundaries using the eight main tidal constituents as derived from the OSU Tidal Prediction Software. The model simulations are performed for the year 2005 using a time step of 60 s. The model reproduces the spring-neap and diurnal and semidiurnal variability in the observed data. Skill assessment of the model is performed by comparing model-predicted surface elevations with observations. For stations located in the central region of the South China Sea, the root mean squared errors (RMSE) are less than 10 % and the Pearson's correlation coefficient ( r) is as high as 0.9. The simulations show that the quality of the model prediction is dependent on the horizontal grid resolution, coastline accuracy, and boundary locations. The maximum RMSE errors and minimum correlation coefficients occur at Kaohsiung (located in northern South China Sea off Taiwan coast) and Tioman (located in southern South China Sea off Malaysia coast). This may be explained with spectral analysis of sea level residuals and winds, which reveal dynamics at Kaohsiung and Tioman are strongly influenced by the seasonal monsoon winds. Our model demonstrates the importance of tidally driven circulation in the central region of the South China Sea.

  7. Mars Pathfinder meteorological observations on the basis of results of an atmospheric global circulation model

    NASA Technical Reports Server (NTRS)

    Forget, Francois; Hourdin, F.; Talagrand, O.

    1994-01-01

    The Mars Pathfinder Meteorological Package (ASI/MET) will measure the local pressure, temperature, and winds at its future landing site, somewhere between the latitudes 0 deg N and 30 deg N. Comparable measurements have already been obtained at the surface of Mars by the Viking Landers at 22 deg N (VL1) and 48 deg N (VL2), providing much useful information on the martian atmosphere. In particular the pressure measurements contain very instructive information on the global atmospheric circulation. At the Laboratoire de Meteorologie Dynamique (LMD), we have analyzed and simulated these measurements with a martian atmospheric global circulation model (GCM), which was the first to simulate the martian atmospheric circulation over more than 1 year. The model is able to reproduce rather accurately many observed features of the martian atmosphere, including the long- and short-period oscillations of the surface pressure observed by the Viking landers. From a meteorological point of view, we think that a landing site located near or at the equator would be an interesting choice.

  8. An Improved Heat Budget Estimation Including Bottom Effects for General Ocean Circulation Models

    NASA Technical Reports Server (NTRS)

    Carder, Kendall; Warrior, Hari; Otis, Daniel; Chen, R. F.

    2001-01-01

    This paper studies the effects of the underwater light field on heat-budget calculations of general ocean circulation models for shallow waters. The presence of a bottom significantly alters the estimated heat budget in shallow waters, which affects the corresponding thermal stratification and hence modifies the circulation. Based on the data collected during the COBOP field experiment near the Bahamas, we have used a one-dimensional turbulence closure model to show the influence of the bottom reflection and absorption on the sea surface temperature field. The water depth has an almost one-to-one correlation with the temperature rise. Effects of varying the bottom albedo by replacing the sea grass bed with a coral sand bottom, also has an appreciable effect on the heat budget of the shallow regions. We believe that the differences in the heat budget for the shallow areas will have an influence on the local circulation processes and especially on the evaporative and long-wave heat losses for these areas. The ultimate effects on humidity and cloudiness of the region are expected to be significant as well.

  9. Study of natural circulation in a VHTR after a LOFA using different turbulence models

    SciTech Connect

    Yu-Hsin Tung; Yuh-Ming Ferng; Richard W. Johnson; Ching-Chang Chieng

    2013-10-01

    Natural convection currents in the core are anticipated in the event of the failure of the gas circulator in a prismatic gas-cooled very high temperature reactor (VHTR). The paths that the helium coolant takes in forming natural circulation loops and the effective heat transport are of interest. The heated flow in the reactor core is turbulent during normal operating conditions and at the beginning of the LOFA with forced convection, but the flow may significantly be slowed down after the event and laminarized with mixed convection. In the present study, the potential occurrence and effective heat transport of natural circulation are demonstrated using computational fluid dynamic (CFD) calculations with different turbulence models as well as laminar flow. Validations and recommendation on turbulence model selection are conducted. The study concludes that large loop natural convection is formed due to the enhanced turbulence levels by the buoyancy effect and the turbulent regime near the interface of upper plenum and flow channels increases the flow resistance for channel flows entering upper plenum and thus less heat can be removed from the core than the prediction by laminar flow assumption.

  10. Numerical Simulations and Tracer Studies as a Tool to Support Water Circulation Modeling in Breeding Reservoirs

    NASA Astrophysics Data System (ADS)

    Zima, Piotr

    2014-12-01

    The article presents a proposal of a method for computer-aided design and analysis of breeding reservoirs in zoos and aquariums. The method applied involves the use of computer simulations of water circulation in breeding pools. A mathematical model of a pool was developed, and a tracer study was carried out. A simplified model of two-dimensional flow in the form of a biharmonic equation for the stream function (converted into components of the velocity vector) was adopted to describe the flow field. This equation, supplemented by appropriate boundary conditions, was solved numerically by the finite difference method. Next, a tracer migration equation was solved, which was a two-dimensional advection-dispersion equation describing the unsteady transport of a non-active, permanent solute. In order to obtain a proper solution, a tracer study (with rhodamine WT as a tracer) was conducted in situ. The results of these measurements were compared with numerical solutions obtained. The results of numerical simulations made it possible to reconstruct water circulation in the breading pool and to identify still water zones, where water circulation was impeded.

  11. Atmospheric Circulation Over Northern Eurasia and the Arctic: Assessment of Modeling Performance and Resolution Issue

    NASA Astrophysics Data System (ADS)

    Shkolnik, I.; Efimov, S.

    2012-12-01

    A system of MGO global and regional atmospheric models is applied for climate studies in the Arctic region. The modeling system is driven by the observed SST/Ice boundary conditions for the period 1981-1990. It has been shown that the embedded RCM has reasonable skill in downscaling GCM simulated thermal regime and circulation patterns in the Arctic and Northern Eurasia. It should be emphasized, however, that there is significant uncertainty across reanalyses in representation of the observed cyclonic activity in the region depending on the resolution. It has been found that the use of different lateral boundary conditions for RCM simulations (e.g., derived from reanalyses and GCM) weakly affects reproduced atmospheric circulation properties suggesting very large internal variability of the Arctic climate system itself. Further research is needed to order to assess current and future circulation changes in the northern high latitudes and associated changes in the extremes (storm surges, frequency and intensity of heat/cold outbreaks in the Arctic, etc.). The study is supported by RFBR grant 11-05-00733.

  12. Variational data assimilation system with nesting model for high resolution ocean circulation

    NASA Astrophysics Data System (ADS)

    Ishikawa, Yoichi; In, Teiji; Nakada, Satoshi; Nishina, Kei; Igarashi, Hiromichi; Hiyoshi, Yoshimasa; Sasaki, Yuji; Wakamatsu, Tsuyoshi; Awaji, Toshiyuki

    2015-10-01

    To obtain the high-resolution analysis fields for ocean circulation, a new incremental approach is developed using a four-dimensional variational data assimilation system with nesting models. The results show that there are substantial biases when using a classical method combined with data assimilation and downscaling, caused by different dynamics resulting from the different resolutions of the models used within the nesting models. However, a remarkable reduction in biases of the low-resolution model relative to the high-resolution model was observed using our new approach in narrow strait regions, such as the Tsushima and Tsugaru straits, where the difference in the dynamics represented by the high- and low-resolution models is substantial. In addition, error reductions are demonstrated in the downstream region of these narrow channels associated with the propagation of information through the model dynamics.

  13. Advanced Model for Extreme Lift and Improved Aeroacoustics (AMELIA)

    NASA Technical Reports Server (NTRS)

    Lichtwardt, Jonathan; Paciano, Eric; Jameson, Tina; Fong, Robert; Marshall, David

    2012-01-01

    With the very recent advent of NASA's Environmentally Responsible Aviation Project (ERA), which is dedicated to designing aircraft that will reduce the impact of aviation on the environment, there is a need for research and development of methodologies to minimize fuel burn, emissions, and reduce community noise produced by regional airliners. ERA tackles airframe technology, propulsion technology, and vehicle systems integration to meet performance objectives in the time frame for the aircraft to be at a Technology Readiness Level (TRL) of 4-6 by the year of 2020 (deemed N+2). The proceeding project that investigated similar goals to ERA was NASA's Subsonic Fixed Wing (SFW). SFW focused on conducting research to improve prediction methods and technologies that will produce lower noise, lower emissions, and higher performing subsonic aircraft for the Next Generation Air Transportation System. The work provided in this investigation was a NASA Research Announcement (NRA) contract #NNL07AA55C funded by Subsonic Fixed Wing. The project started in 2007 with a specific goal of conducting a large-scale wind tunnel test along with the development of new and improved predictive codes for the advanced powered-lift concepts. Many of the predictive codes were incorporated to refine the wind tunnel model outer mold line design. The large scale wind tunnel test goal was to investigate powered lift technologies and provide an experimental database to validate current and future modeling techniques. Powered-lift concepts investigated were Circulation Control (CC) wing in conjunction with over-the-wing mounted engines to entrain the exhaust to further increase the lift generated by CC technologies alone. The NRA was a five-year effort; during the first year the objective was to select and refine CESTOL concepts and then to complete a preliminary design of a large-scale wind tunnel model for the large scale test. During the second, third, and fourth years the large-scale wind

  14. Numerical model of circulation and residence times in the Persian Gulf

    NASA Astrophysics Data System (ADS)

    O'Donncha, Fearghal; Ragnoli, Emanuele

    2014-05-01

    The Persian Gulf is a semi-enclosed, marginal sea that is exposed to arid, subtropical climate. As a consequence of the extreme climate, evaporation is greater than freshwater inflow resulting in a net loss of water and associated, reverse flow, estuarine circulation as the highly saline waters exit the basin through the Straits of Hormuz, into the Gulf of Oman. Because of their consistent direction, these density currents are central in the distribution and removal of pollutants from the gulf. Tidal forcing impacts circulation in the region, particularly on smaller scales of length and time. Wind forcing can be significant, particularly the Shamal weather phenomenon; wind that sets in with great abruptness and force, and is related to synoptic weather systems to the Northwest. Output from high resolution (~1km) numerical simulations, using NEMO (Nucleus for European Modelling of the Ocean), provide insight into the physical oceanography of the region. The model was forced by 0.75° European Centre for Medium-Range Weather Forecasts (ECMWF) atmospheric data and tidal constituents extracted from the Oregon State University Tidal Prediction Software (OTPS/TPXO). Model results permit a detailed examination of the three primary forcing processes, namely: tidal forces, wind forces, and density differences. To assess fundamental model performance, results are compared with two historical observation datasets: (1) a comprehensive dataset of velocity and CTD measurements collected by Reynolds (1993) and (2) time series measurements recorded in the Strait of Hormuz from December 1996 to March 1998 by Johns et al. (2003). Model results exhibit close agreement to field values validating the model for a more detailed analysis of circulations patterns within the gulf. To better elucidate the dominant forcing processes, classical tidal analysis decomposed the flow currents by fitting the flow profile to a finite set of sinusoids at specific frequencies related to astronomical

  15. A 3D, finite element model for baroclinic circulation on the Vancouver Island continental shelf

    USGS Publications Warehouse

    Walters, R.A.; Foreman, M.G.G.

    1992-01-01

    This paper describes the development and application of a 3-dimensional model of the barotropic and baroclinic circulation on the continental shelf west of Vancouver Island, Canada. A previous study with a 2D barotropic model and field data revealed that several tidal constituents have a significant baroclinic component (the K1 in particular). Thus we embarked on another study with a 3D model to study the baroclinic effects on the residual and several selected tidal constituents. The 3D model uses a harmonic expansion in time and a finite element discretization in space. All nonlinear terms are retained, including quadratic bottom stress, advection and wave transport (continuity nonlinearity). The equations are solved as a global and a local problem, where the global problem is the solution of the wave equation formulation of the shallow water equations, and the local problem is the solution of the momentum equation for the vertical velocity profile. These equations are coupled to the advection-diffusion equation for density so that density gradient forcing is included in the momentum equations. However, the study presented here describes diagnostic calculations for the baroclinic residual circulation only. The model is sufficiently efficient that it encourages sensitivity testing with a large number of model runs. In this sense, the model is akin to an extension of analytical solutions to the domain of irregular geometry and bottom topography where this parameter space can be explored in some detail. In particular, the consequences of the sigma coordinate system used by the model are explored. Test cases using an idealized representation of the continental shelf, shelf break and shelf slope, lead to an estimation of the velocity errors caused by interpolation errors inherent in the sigma coordinate system. On the basis of these estimates, the computational grid used in the 2D model is found to have inadequate resolution. Thus a new grid is generated with increased

  16. Winter polar warmings and the meridional transport on Mars simulated with a general circulation model

    NASA Astrophysics Data System (ADS)

    Medvedev, Alexander S.; Hartogh, Paul

    2007-01-01

    Winter polar warmings in the middle atmosphere of Mars occur due to the adiabatic heating associated with the downward branch of the cross-equatorial meridional circulation. Thus, they are the manifestation of the global meridional transport rather than of local radiative effects. We report on a series of numerical experiments with a recently developed general circulation model of the martian atmosphere to examine the relative roles of the mechanical and thermal forcing in the meridional transport. The experiments were focused on answering the question of whether the martian circulation is consistent with the thermally driven nearly inviscid Hadley cell, as was pointed out by some previous studies, or it is forced mainly by zonally asymmetric eddies. It is demonstrated that, under realistic conditions in the middle atmosphere, the meridional transport is maintained primarily by dissipating large-scale planetary waves and solar tides. This mechanism is similar to the "extratropical pump" in the middle atmosphere on Earth. Only in the run with artificially weak zonal disturbances, was the circulation reminiscent of thermally induced Hadley cells. In the experiment with an imposed dust storm, the modified atmospheric refraction changes the vertical propagation of the eddies. As the result, the Eliassen-Palm fluxes convergence increases in high winter latitudes of the middle atmosphere, the meridional transport gets stronger, and the polar temperature rises. Additional numerical experiments demonstrated that insufficient model resolution, increased numerical dissipation, and, especially, neglect of non-LTE effects for the 15 μm CO 2 band could weaken the meridional transport and the magnitude of polar warmings in GCMs.

  17. Three-dimensional modelling of coastal circulations with different k- ɛ closures

    NASA Astrophysics Data System (ADS)

    Verdier-Bonnet, C.; Angot, Philippe; Fraunie, Philippe; Coantic, M.

    1999-06-01

    The actual tendency in 3D turbulent closure models for stratified shallow water flows is to come back to closure models with two transport equations for turbulent variables or to algebraic flux models. We retain the simpler k- ɛ closure model. For a simplified coastal upwelling circulation, we studied the relevance of the isotropic eddy viscosity assumption of the standard k-ɛ model for stratified and shallow-water flows submitted to the Coriolis force with two corrected k-ɛ models: STRAT-COR and ASPECT. We considered two mean sources of coastal turbulence production: the surface current shear generated by wind and the bottom shear. In order to understand the processes involved, we have modelled academic configurations such as constant depth ones or one-dimensional vertical problems. For a simplified coastal upwelling circulation, we have studied the pertinence of the isotropic eddy viscosity assumption of the standard k-ɛ model for stratified and shallow-water flows submitted to the Coriolis force. In order to take into account those non-isotropic behaviour of turbulence, we have used two corrected k-ɛ models: STRAT-COR and ASPECT. But, the mean deficiency of this model is the isotropic eddy viscosity assumption. In order to take into account the non-isotropic behaviour of turbulence due to buoyancy and Coriolis forces, a hybrid turbulence model (STRAT-COR) combining the standard k- ɛ and algebraic Reynolds stress models, is used. For shallow-water flows ( δ=( L)/( H)≫1) two eddies length scales can be pointed out: L for the large horizontal structures and H for the smaller but 3D ones. These effects are represented by a correction to the standard k- ɛ model, based on the separation of two turbulence scales, respectively associated to L and H. We focus our study onto two main sources of turbulent oceanic energy: the surface current shear induced by wind and the bottom stress due to tidal circulation. The k- ɛ closure model corrected to account for non

  18. Responses of estuarine circulation and salinity to the loss of intertidal flats - A modeling study

    NASA Astrophysics Data System (ADS)

    Yang, Zhaoqing; Wang, Taiping

    2015-12-01

    Intertidal flats in estuaries are coastal wetlands that provide critical marine habitats to support wide ranges of marine species. Over the last century many estuarine systems have experienced significant loss of intertidal flats due to anthropogenic impacts. This paper presents a modeling study conducted to investigate the responses of estuarine hydrodynamics to the loss of intertidal flats in Whidbey Basin of Puget Sound on the northwest coast of North America. Changes in salinity intrusion limits in the estuaries, salinity stratification, and circulation in intertidal flats and estuaries were evaluated by comparing model results under the existing baseline condition and the no-flat condition. Model results showed that loss of intertidal flats results in an increase in salinity intrusion, stronger mixing, and a phase shift in salinity and velocity fields in the bay front areas. Model results also indicated that loss of intertidal flats enhances two-layer circulation, especially the bottom water intrusion. Loss of intertidal flats increases the mean salinity but reduces the salinity range in the subtidal flats over a tidal cycle because of increased mixing. Salinity intrusion limits extend upstream in all three major rivers discharging into Whidbey Basin when no intertidal flats are present. Changes in salinity intrusion and estuarine circulation patterns due to loss of intertidal flats affect the nearshore habitat and water quality in estuaries and potentially increase risk of coastal hazards, such as storm surge and coastal flooding. Lastly, model results suggested the importance of including intertidal flats and the wetting-and-drying process in hydrodynamic simulations when intertidal flats are present in the model domain.

  19. Progress in General Circulation Modeling of Recent Climate Change on Mars

    NASA Astrophysics Data System (ADS)

    Haberle, R. M.

    2003-12-01

    The Mars Global Surveyor and Odyssey spacecraft reveal evidence that Mars may have experienced significant climate change in the recent past (105 - 108 My). Examples include gullies, cold-based tropical glaciers, paleolakes, youthful near-surface ice, and recent localized heavy erosion. Except for the gullies and erosion, the evidence for recent climate changes requires ice and/or liquid water at low latitudes. An obvious question, therefore, is how is it possible for ice and/or liquid water to exist at low latitudes which is not possible in the present climate system? Possible mechanisms for recent climate change are volcanism, impacts, polar wander, solar variability, and orbital changes. Of these, orbital changes are the least controversial and most widely accepted mechanism for climate change. Jakosky and Carr (1985) used simple scaling arguments to suggest that at high obliquity water evaporating from the north polar cap would be transported southward by the general circulation and precipitate out at low latitudes forming tropical ice deposits. General circulation models have since confirmed this prediction. However the location and abundance of the GCM-predicted deposits varies from model to model for a given orbital configuration. The reason for this variability is probably related to how the processes that control the water cycle are represented in the models. Thus far, the models run for these high obliquity cases have simple representations of cloud microphysical processes, and totally ignore the radiative effects of water vapor and clouds. Regolith exchange and dust/ice interactions are also neglected. This talk will review the current status of general circulation modeling of recent climate change and the directions future efforts are headed towards. Reference: Jakosky, B.M., and M.H. Carr (1985). Nature, 315, 559-561.

  20. Responses of estuarine circulation and salinity to the loss of intertidal flats – A modeling study

    DOE PAGES

    Yang, Zhaoqing; Wang, Taiping

    2015-08-25

    Intertidal flats in estuaries are coastal wetlands that provide critical marine habitats to support wide ranges of marine species. Over the last century many estuarine systems have experienced significant loss of intertidal flats due to anthropogenic impacts. This paper presents a modeling study conducted to investigate the responses of estuarine hydrodynamics to the loss of intertidal flats caused by anthropogenic actions in Whidbey Basin of Puget Sound on the northwest coast of North America. Changes in salinity intrusion limits in the estuaries, salinity stratification, and circulation in intertidal flats and estuaries were evaluated by comparing model results under the existingmore » baseline condition and the no-flat condition. Model results showed that loss of intertidal flats results in an increase in salinity intrusion, stronger mixing, and a phase shift in salinity and velocity fields in the bay front areas. Model results also indicated that loss of intertidal flats enhances two-layer circulation, especially the bottom water intrusion. Loss of intertidal flats increases the mean salinity but reduces the salinity range in the subtidal flats over a tidal cycle because of increased mixing. Salinity intrusion limits extend upstream in all three major rivers discharging into Whidbey Basin when no intertidal flats are present. Changes in salinity intrusion and estuarine circulation patterns due to loss of intertidal flats affect the nearshore habitat and water quality in estuaries and potentially increase risk of coastal hazards, such as storm surge and coastal flooding. Furthermore, model results suggested the importance of including intertidal flats and the wetting-and-drying process in hydrodynamic simulations when intertidal flats are present in the model domain.« less

  1. Responses of estuarine circulation and salinity to the loss of intertidal flats – A modeling study

    SciTech Connect

    Yang, Zhaoqing; Wang, Taiping

    2015-08-25

    Intertidal flats in estuaries are coastal wetlands that provide critical marine habitats to support wide ranges of marine species. Over the last century many estuarine systems have experienced significant loss of intertidal flats due to anthropogenic impacts. This paper presents a modeling study conducted to investigate the responses of estuarine hydrodynamics to the loss of intertidal flats caused by anthropogenic actions in Whidbey Basin of Puget Sound on the northwest coast of North America. Changes in salinity intrusion limits in the estuaries, salinity stratification, and circulation in intertidal flats and estuaries were evaluated by comparing model results under the existing baseline condition and the no-flat condition. Model results showed that loss of intertidal flats results in an increase in salinity intrusion, stronger mixing, and a phase shift in salinity and velocity fields in the bay front areas. Model results also indicated that loss of intertidal flats enhances two-layer circulation, especially the bottom water intrusion. Loss of intertidal flats increases the mean salinity but reduces the salinity range in the subtidal flats over a tidal cycle because of increased mixing. Salinity intrusion limits extend upstream in all three major rivers discharging into Whidbey Basin when no intertidal flats are present. Changes in salinity intrusion and estuarine circulation patterns due to loss of intertidal flats affect the nearshore habitat and water quality in estuaries and potentially increase risk of coastal hazards, such as storm surge and coastal flooding. Furthermore, model results suggested the importance of including intertidal flats and the wetting-and-drying process in hydrodynamic simulations when intertidal flats are present in the model domain.

  2. Thermohaline Circulation Stability: A Box Model Study. Part II: Coupled Atmosphere-Ocean Model.

    NASA Astrophysics Data System (ADS)

    Lucarini, Valerio; Stone, Peter H.

    2005-02-01

    A thorough analysis of the stability of a coupled version of an interhemispheric three-box model of thermohaline circulation (THC) is presented. This study follows a similarly structured analysis of an uncoupled version of the same model presented in Part I of this paper. The model consists of a northern high-latitude box, a tropical box, and a southern high-latitude box, which can be thought of as corresponding to the northern, tropical, and southern Atlantic Ocean, respectively. This paper examines how the strength of THC changes when the system undergoes forcings representing global warming conditions.Since a coupled model is used, a direct representation of the radiative forcing is possible because the main atmospheric physical processes responsible for freshwater and heat fluxes are formulated separately. Each perturbation to the initial equilibrium is characterized by the total radiative forcing realized, by the rate of increase, and by the north-south asymmetry. Although only weakly asymmetric or symmetric radiative forcings are representative of physically reasonable conditions, general asymmetric forcings are considered in order to get a more complete picture of the mathematical properties of the system. The choice of suitably defined metrics makes it possible to determine the boundary dividing the set of radiative forcing scenarios that lead the system to equilibria characterized by a THC pattern similar to the present one, from those that drive the system to equilibria where the THC is reversed. This paper also considers different choices for the atmospheric transport parameterizations and for the ratio between the high-latitude and tropical radiative forcing. It is generally found that fast forcings are more effective than slow forcings in disrupting the present THC pattern, forcings that are stronger in the northern box are also more effective in destabilizing the system, and very slow forcings do not destabilize the system whatever their asymmetry

  3. General circulation model simulations of winter and summer sea-level pressures over North America

    USGS Publications Warehouse

    McCabe, G.J.; Legates, D.R.

    1992-01-01

    In this paper, observed sea-level pressures were used to evaluate winter and summer sea-level pressures over North America simulated by the Goddard Institute for Space Studies (GISS) and the Geophysical Fluid Dynamics Laboratory (GFDL) general circulation models. The objective of the study is to determine how similar the spatial and temporal distributions of GCM-simulated daily sea-level pressures over North America are to observed distributions. Overall, both models are better at reproducing observed within-season variance of winter and summer sea-level pressures than they are at simulating the magnitude of mean winter and summer sea-level pressures. -from Authors

  4. Heat balance statistics derived from four-dimensional assimilations with a global circulation model

    NASA Technical Reports Server (NTRS)

    Schubert, S. D.; Herman, G. F.

    1981-01-01

    The reported investigation was conducted to develop a reliable procedure for obtaining the diabatic and vertical terms required for atmospheric heat balance studies. The method developed employs a four-dimensional assimilation mode in connection with the general circulation model of NASA's Goddard Laboratory for Atmospheric Sciences. The initial analysis was conducted with data obtained in connection with the 1976 Data Systems Test. On the basis of the results of the investigation, it appears possible to use the model's observationally constrained diagnostics to provide estimates of the global distribution of virtually all of the quantities which are needed to compute the atmosphere's heat and energy balance.

  5. Progress on physical circulation and ecosystem modeling in the COAST and WEST programs

    NASA Astrophysics Data System (ADS)

    Allen, J. S.

    2002-12-01

    High resolution physical circulation and ecosystem models have been applied to study the mesoscale shelf flow field and ecosystem response off Oregon and northern California in the regions of the COAST and WEST field experiments. Localized, regional domains that extend approximately 400-600 km alongshore and 200-300 km offshore are utilized to allow high horizontal grid resolutions of 1-2 km. The Princeton Ocean Model (POM) is used for Oregon while the ROMS model is used for northern California. The Oregon ecosystem model is a five component nitrogen-based NNPZD model. In the most basic, workhorse configuration, periodicity conditions are used at the alongshore boundaries, allowing the specification of well-posed problems. For these shelf flows, where the mesoscale behavior is dominated by the interaction of wind-driven currents with variable shelf topography, that approximation leads to model results that generally show good agreement with observations. Open boundary conditions have also been developed to allow the application of spatially-variable forcing obtained from a high resolution mesoscale atmospheric model. In addition, off Oregon a data assimilation system utilizing HF-radar surface current measurements and a sequential optimal interpolation scheme is being utilized to improve estimates of the circulation. These models have been applied to the spring and summer 2001 time periods of the COAST and WEST field experiments. The modeled mesoscale shelf flow field off Oregon is strongly influenced by interactions with Heceta Bank while the flow off northern California is affected in a major way by Point Reyes. The structure of model sea surface temperature fields reflects the shelf flow interaction with these topographic features and is in good qualitative agreement with comparable satellite-measured fields. New information on the three-dimensional time-dependent nature of the velocity, temperature, and turbulent kinetic energy fields, tested with model

  6. Infrared cooling rate calculations in operational general circulation models - Comparisons with benchmark computations

    NASA Technical Reports Server (NTRS)

    Kiehl, J. T.; Lacis, A. A.; Schwarzkopf, M. D.; Fels, S. B.

    1991-01-01

    The performance of several parameterized models is described with respect to numerical prediction and climate research at GFDL, NCAR, and GISS. The radiation codes of the models were compared to benchmark calculations and other codes for the intercomparison of radiation codes in climate models (ICRCCM). Cooling rates and fluxes calculated from the models are examined in terms of their application to established general circulation models (GCMs) from the three research institutions. The newest radiation parameterization techniques show the most significant agreement with the benchmark line-by-line (LBL) results. The LBL cooling rates correspond to cooling rate profiles from the models, but the parameterization of the water vapor continuum demonstrates uncertain results. These uncertainties affect the understanding of some lower tropospheric cooling, and therefore more accurate parameterization of the water vapor continuum, as well as the weaker absorption bands of CO2 and O3 is recommended.

  7. Development of numerical model for material circulation around seabed sediment at coastal area

    NASA Astrophysics Data System (ADS)

    Tsukahara, Y.; Nakatani, N.; Yamazaki, T.

    2012-12-01

    In enclosed coastal seas, many organic matters are deposited at the seabed because of excessive pollution load from rivers. Organic materials are decomposed by several bacteria with consumption of dissolved oxygen in the bottom water. Consequently, dysoxic water mass are formed and aerobium decreases drastically. Due to dysoxic water mass, some environmental problems are posed such as eluting hydrogen sulfide and blue tide. It is essential to grasp an understanding for decomposition of organic material and exchange of nutrients and oxygen between the seabed sediment and the bottom water. To clarify material circulation in seabed sediment, it is effective and useful to simulation using numerical model. Fossing et al. (2004) constructed numerical model represented material circulation included phosphorus dynamic state around the seabed sediment in Arhus Bay. Alternatively, Nagao et al. (2008) and Irie et al. (2010) estimated elution rate based on numerical model using Fossing's model. However, it is incomplete to describe the vertical profiles and elution rate of some materials. These results are thought to be due to lack of knowledge for degradation processes in the seabed and other chemical reactions. In this research, dynamic state of each material circulation is investigated using an experimental aquarium that enable to sampling pore water in seabed sediment intermittently. In additional approach, field work is conducted in Amagasaki Bay regarded as coastal area polluted significantly. Authors modified more precisely Fossing's model by comparing and applying these results of experiment and field works. Results of our research can accumulate a scientific knowledge about effect of deposition in the seabed sediment to coastal area.;

  8. AFDM: An Advanced Fluid-Dynamics Model

    SciTech Connect

    Bohl, W.R.; Parker, F.R. ); Wilhelm, D. . Inst. fuer Neutronenphysik und Reaktortechnik); Berthier, J. ); Goutagny, L. . Inst. de Protection et de Surete Nucleaire); Ninokata,

    1990-09-01

    AFDM, or the Advanced Fluid-Dynamics Model, is a computer code that investigates new approaches simulating the multiphase-flow fluid-dynamics aspects of severe accidents in fast reactors. The AFDM formalism starts with differential equations similar to those in the SIMMER-II code. These equations are modified to treat three velocity fields and supplemented with a variety of new models. The AFDM code has 12 topologies describing what material contacts are possible depending on the presence or absence of a given material in a computational cell, on the dominant liquid, and on the continuous phase. Single-phase, bubbly, churn-turbulent, cellular, and dispersed flow regimes are permitted for the pool situations modeled. Virtual mass terms are included for vapor in liquid-continuous flow. Interfacial areas between the continuous and discontinuous phases are convected to allow some tracking of phenomenological histories. Interfacial areas are also modified by models of nucleation, dynamic forces, turbulence, flashing, coalescence, and mass transfer. Heat transfer is generally treated using engineering correlations. Liquid-vapor phase transitions are handled with the nonequilibrium, heat-transfer-limited model, whereas melting and freezing processes are based on equilibrium considerations. Convection is treated using a fractional-step method of time integration, including a semi-implicit pressure iteration. A higher-order differencing option is provided to control numerical diffusion. The Los Alamos SESAME equation-of-state has been implemented using densities and temperatures as the independent variables. AFDM programming has vectorized all computational loops consistent with the objective of producing an exportable code. 24 refs., 4 figs.

  9. Nonlinear Dynamic Models in Advanced Life Support

    NASA Technical Reports Server (NTRS)

    Jones, Harry

    2002-01-01

    To facilitate analysis, ALS systems are often assumed to be linear and time invariant, but they usually have important nonlinear and dynamic aspects. Nonlinear dynamic behavior can be caused by time varying inputs, changes in system parameters, nonlinear system functions, closed loop feedback delays, and limits on buffer storage or processing rates. Dynamic models are usually cataloged according to the number of state variables. The simplest dynamic models are linear, using only integration, multiplication, addition, and subtraction of the state variables. A general linear model with only two state variables can produce all the possible dynamic behavior of linear systems with many state variables, including stability, oscillation, or exponential growth and decay. Linear systems can be described using mathematical analysis. Nonlinear dynamics can be fully explored only by computer simulations of models. Unexpected behavior is produced by simple models having only two or three state variables with simple mathematical relations between them. Closed loop feedback delays are a major source of system instability. Exceeding limits on buffer storage or processing rates forces systems to change operating mode. Different equilibrium points may be reached from different initial conditions. Instead of one stable equilibrium point, the system may have several equilibrium points, oscillate at different frequencies, or even behave chaotically, depending on the system inputs and initial conditions. The frequency spectrum of an output oscillation may contain harmonics and the sums and differences of input frequencies, but it may also contain a stable limit cycle oscillation not related to input frequencies. We must investigate the nonlinear dynamic aspects of advanced life support systems to understand and counter undesirable behavior.

  10. Advances in Swine Biomedical Model Genomics

    PubMed Central

    Lunney, Joan K.

    2007-01-01

    This review is a short update on the diversity of swine biomedical models and the importance of genomics in their continued development. The swine has been used as a major mammalian model for human studies because of the similarity in size and physiology, and in organ development and disease progression. The pig model allows for deliberately timed studies, imaging of internal vessels and organs using standard human technologies, and collection of repeated peripheral samples and, at kill, detailed mucosal tissues. The ability to use pigs from the same litter, or cloned or transgenic pigs, facilitates comparative analyses and genetic mapping. The availability of numerous well defined cell lines, representing a broad range of tissues, further facilitates testing of gene expression, drug susceptibility, etc. Thus the pig is an excellent biomedical model for humans. For genomic applications it is an asset that the pig genome has high sequence and chromosome structure homology with humans. With the swine genome sequence now well advanced there are improving genetic and proteomic tools for these comparative analyses. The review will discuss some of the genomic approaches used to probe these models. The review will highlight genomic studies of melanoma and of infectious disease resistance, discussing issues to consider in designing such studies. It will end with a short discussion of the potential for genomic approaches to develop new alternatives for control of the most economically important disease of pigs, porcine reproductive and respiratory syndrome (PRRS), and the potential for applying knowledge gained with this virus for human viral infectious disease studies. PMID:17384736

  11. Modeling of advanced fossil fuel power plants

    NASA Astrophysics Data System (ADS)

    Zabihian, Farshid

    The first part of this thesis deals with greenhouse gas (GHG) emissions from fossil fuel-fired power stations. The GHG emission estimation from fossil fuel power generation industry signifies that emissions from this industry can be significantly reduced by fuel switching and adaption of advanced power generation technologies. In the second part of the thesis, steady-state models of some of the advanced fossil fuel power generation technologies are presented. The impacts of various parameters on the solid oxide fuel cell (SOFC) overpotentials and outputs are investigated. The detail analyses of operation of the hybrid SOFC-gas turbine (GT) cycle when fuelled with methane and syngas demonstrate that the efficiencies of the cycles with and without anode exhaust recirculation are close, but the specific power of the former is much higher. The parametric analysis of the performance of the hybrid SOFC-GT cycle indicates that increasing the system operating pressure and SOFC operating temperature and fuel utilization factor improves cycle efficiency, but the effects of the increasing SOFC current density and turbine inlet temperature are not favourable. The analysis of the operation of the system when fuelled with a wide range of fuel types demonstrates that the hybrid SOFC-GT cycle efficiency can be between 59% and 75%, depending on the inlet fuel type. Then, the system performance is investigated when methane as a reference fuel is replaced with various species that can be found in the fuel, i.e., H2, CO2, CO, and N 2. The results point out that influence of various species can be significant and different for each case. The experimental and numerical analyses of a biodiesel fuelled micro gas turbine indicate that fuel switching from petrodiesel to biodiesel can influence operational parameters of the system. The modeling results of gas turbine-based power plants signify that relatively simple models can predict plant performance with acceptable accuracy. The unique

  12. Use of Advanced Meteorological Model Output for Coastal Ocean Modeling in Puget Sound

    SciTech Connect

    Yang, Zhaoqing; Khangaonkar, Tarang; Wang, Taiping

    2011-06-01

    It is a great challenge to specify meteorological forcing in estuarine and coastal circulation modeling using observed data because of the lack of complete datasets. As a result of this limitation, water temperature is often not simulated in estuarine and coastal modeling, with the assumption that density-induced currents are generally dominated by salinity gradients. However, in many situations, temperature gradients could be sufficiently large to influence the baroclinic motion. In this paper, we present an approach to simulate water temperature using outputs from advanced meteorological models. This modeling approach was applied to simulate annual variations of water temperatures of Puget Sound, a fjordal estuary in the Pacific Northwest of USA. Meteorological parameters from North American Region Re-analysis (NARR) model outputs were evaluated with comparisons to observed data at real-time meteorological stations. Model results demonstrated that NARR outputs can be used to drive coastal ocean models for realistic simulations of long-term water-temperature distributions in Puget Sound. Model results indicated that the net flux from NARR can be further improved with the additional information from real-time observations.

  13. General circulation modeling of the thermosphere-ionosphere during a geomagnetic storm

    NASA Astrophysics Data System (ADS)

    Yiǧit, Erdal; Immel, Thomas; Ridley, Aaron; Frey, Harald U.; Moldwin, Mark

    2016-07-01

    Using a three-dimensional general circulation model (GCM) of the upper atmosphere, we investigate the response of the thermosphere-ionosphere system to the August 2011 major geomagnetic storm. The GCM is driven by measured storm-time input data of the Interplanetary Magnetic Field (IMF), solar activity, and auroral activity. Simulations for quiet steady conditions over the same period are performed as well in order to assess the response of the neutral and plasma parameters to the storm. During the storm, the high-latitude mean ion flows are enhanced by up to ~150%. Overall, the global mean neutral temperature increases by up to 15%, while the maximum thermal response is higher in the winter Southern Hemisphere at high-latitudes than the summer Northern Hemisphere: 40% vs. 20% increase in high-latitude mean temperature, respectively. The global mean Joule heating of the neutral atmosphere increases by more than a factor of three. There are distinct hemispheric differences in the magnitude and morphology of the horizontal ion flows and thermospheric circulation during the different phases of the storm. The thermospheric circulation demonstrates the largest amount of hemispheric differences during the later stages of the storm. Dynamical diagnostics show that advective forcing contributes to hemispheric differences.

  14. Global aspects of the Los Alamos general circulation model hydrologic cycle

    NASA Technical Reports Server (NTRS)

    Roads, J. O.; Chen, S.-C.; Kao, J.; Langley, D.; Glatzmaier, G.

    1992-01-01

    The global hydrologic cycle in the Los Alamos general circulation model (GCM) is compared to available global observations. Global observations of the water vapor, water-vapor flux and water-vapor flux divergence are derived from the National Meteorological Center's final analysis for the period 1986-1989. The new precipitation data set of Legates and Willmott (1990) is used for the global precipitation observations. Global evaporation is derived as a residual of the precipitation and water-vapor flux divergence. There are a number of similarities as well as discrepancies between the GCM and observations. The large-scale nondivergent and divergent GCM circulations are remarkably similar to the observed circulations; the large-scale GCM precipitation and evaporation patterns are also qualitatively similar to observations. Discrepancies are mainly quantitative and small-scale in nature: the GCM atmosphere is relatively dry which results in a slightly greater evaporation and precipitation rate than is observed; the GCM South Pacific convergence zone is displaced too far to the northwest.

  15. Navier-Stokes calculations and turbulence modeling in the trailing edge region of a circulation control airfoil

    NASA Technical Reports Server (NTRS)

    Viegas, John R.; Rubesin, Morris W.; Maccormack, Robert W.

    1987-01-01

    The accurate prediction of turbulent flows over curved surfaces in general and over the trailing edge region of circulation control airfoils in particular requires the coupled efforts of turbulence modelers, numerical analysts and experimentalists. The purpose of the research program in this area is described. Then, the influence on turbulence modeling of the flow characteristics over a typical circulation control wing is discussed. Next, the scope of this effort to study turbulence in the trailing edge region of a circulation control airfoil is presented. This is followed by a brief overview of the computation scheme, including the grid, governing equations, numerical method, boundary conditions and turbulence models applied to date. Then, examples of applications of two algebraic eddy viscosity models to the trailing edge region of a circulation control airfoil is presented. The results from the calculations is summarized, and conclusions drawn based on examples. Finally, the future directions of the program is outlined.

  16. Usefulness of circulating free DNA for monitoring epidermal growth factor receptor mutations in advanced non-small cell lung cancer patients: a case report

    PubMed Central

    Gonzalez-Cao, Maria; Ramirez, Santiago Viteri; Ariza, Nuria Jordana; Balada, Ariadna; Garzón, Mónica; Teixidó, Cristina; Karachaliou, Niki; Morales-Espinosa, Daniela; Molina-Vila, Miguel Ángel; Rosell, Rafael

    2016-01-01

    Genomic analysis of circulating tumor DNA (ctDNA) released from cancer cells into the bloodstream has been proposed as a useful method to capture dynamic changes during the course of the disease. In particular, the ability to monitor epidermal growth factor receptor (EGFR) mutation status in cell-free circulating DNA (cfDNA) isolated from advanced non-small cell lung cancer (NSCLC) patients EGFR can help to the correct management of the disease and overcome the challenges associated with tumor heterogeneity and insufficient biopsied material to perform key molecular diagnosis. Here, we report a case of long term monitorization of EGFR mutation status in cfDNA from peripheral blood in an NSCLC patient in, with excellent correlation with clinical evolution. PMID:27826535

  17. Multiscale dynamical analysis of a high-resolution numerical model simulation of the Solomon Sea circulation

    NASA Astrophysics Data System (ADS)

    Djath, Bughsin'; Verron, Jacques; Melet, Angelique; Gourdeau, Lionel; Barnier, Bernard; Molines, Jean-Marc

    2014-09-01

    A high 1/36° resolution numerical model is used to study the ocean circulation in the Solomon Sea. An evaluation of the model with (the few) available observation shows that the 1/36° resolution model realistically simulates the Solomon Sea circulations. The model notably reproduces the high levels of mesoscale eddy activity observed in the Solomon Sea. With regard to previous simulations at 1/12° resolution, the average eddy kinetic energy levels are increased by up to ˜30-40% in the present 1/36° simulation, and the enhancement extends at depth. At the surface, the eddy kinetic energy level is maximum in March-April-May and is minimum in December-January-February. The high subsurface variability is related to the variability of the western boundary current (New Guinea Coastal Undercurrent). Moreover, the emergence of submesoscales is clearly apparent in the present simulations. A spectral analysis is conducted in order to evidence and characterize the modeled submesoscale dynamics and to provide a spectral view of scales interactions. The corresponding spectral slopes show a strong consistency with the Surface Quasi-Geostrophic turbulence theory.

  18. Numerical modeling of the thermoelectric cooler with a complementary equation for heat circulation in air gaps

    NASA Astrophysics Data System (ADS)

    Fang, En; Wu, Xiaojie; Yu, Yuesen; Xiu, Junrui

    2017-01-01

    In this paper, a numerical model is developed by combining thermodynamics with heat transfer theory. Taking inner and external multi-irreversibility into account, it is with a complementary equation for heat circulation in air gaps of a steady cooling system with commercial thermoelectric modules operating in refrigeration mode. With two modes concerned, the equation presents the heat flowing through air gaps which forms heat circulations between both sides of thermoelectric coolers (TECs). In numerical modelling, a TEC is separated as two temperature controlled constant heat flux reservoirs in a thermal resistance network. In order to obtain the parameter values, an experimental apparatus with a commercial thermoelectric cooler was built to characterize the performance of a TEC with heat source and sink assembly. At constant power dissipation, steady temperatures of heat source and both sides of the thermoelectric cooler were compared with those in a standard numerical model. The method displayed that the relationship between Φf and the ratio Φ_{c}'/Φ_{c} was linear as expected. Then, for verifying the accuracy of proposed numerical model, the data in another system were recorded. It is evident that the experimental results are in good agreement with simulation(proposed model) data at different heat transfer rates. The error is small and mainly results from the instabilities of thermal resistances with temperature change and heat flux, heat loss of the device vertical surfaces and measurements.

  19. A novel microfluidic model can mimic organ-specific metastasis of circulating tumor cells

    PubMed Central

    Kong, Jing; Luo, Yong; Jin, Dong; An, Fan; Zhang, Wenyuan; Liu, Lilu; Li, Jiao; Fang, Shimeng; Li, Xiaojie; Yang, Xuesong; Lin, Bingcheng; Liu, Tingjiao

    2016-01-01

    A biomimetic microsystem might compensate costly and time-consuming animal metastatic models. Herein we developed a biomimetic microfluidic model to study cancer metastasis. Primary cells isolated from different organs were cultured on the microlfuidic model to represent individual organs. Breast and salivary gland cancer cells were driven to flow over primary cell culture chambers, mimicking dynamic adhesion of circulating tumor cells (CTCs) to endothelium in vivo. These flowing artificial CTCs showed different metastatic potentials to lung on the microfluidic model. The traditional nude mouse model of lung metastasis was performed to investigate the physiological similarity of the microfluidic model to animal models. It was found that the metastatic potential of different cancer cells assessed by the microfluidic model was in agreement with that assessed by the nude mouse model. Furthermore, it was demonstrated that the metastatic inhibitor AMD3100 inhibited lung metastasis effectively in both the microfluidic model and the nude mouse model. Then the microfluidic model was used to mimick liver and bone metastasis of CTCs and confirm the potential for research of multiple-organ metastasis. Thus, the metastasis of CTCs to different organs was reconstituted on the microfluidic model. It may expand the capabilities of traditional cell culture models, providing a low-cost, time-saving, and rapid alternative to animal models. PMID:27191997

  20. Large eddy simulation model for wind-driven sea circulation in coastal areas

    NASA Astrophysics Data System (ADS)

    Petronio, A.; Roman, F.; Nasello, C.; Armenio, V.

    2013-12-01

    In the present paper a state-of-the-art large eddy simulation model (LES-COAST), suited for the analysis of water circulation and mixing in closed or semi-closed areas, is presented and applied to the study of the hydrodynamic characteristics of the Muggia bay, the industrial harbor of the city of Trieste, Italy. The model solves the non-hydrostatic, unsteady Navier-Stokes equations, under the Boussinesq approximation for temperature and salinity buoyancy effects, using a novel, two-eddy viscosity Smagorinsky model for the closure of the subgrid-scale momentum fluxes. The model employs: a simple and effective technique to take into account wind-stress inhomogeneity related to the blocking effect of emerged structures, which, in turn, can drive local-scale, short-term pollutant dispersion; a new nesting procedure to reconstruct instantaneous, turbulent velocity components, temperature and salinity at the open boundaries of the domain using data coming from large-scale circulation models (LCM). Validation tests have shown that the model reproduces field measurement satisfactorily. The analysis of water circulation and mixing in the Muggia bay has been carried out under three typical breeze conditions. Water circulation has been shown to behave as in typical semi-closed basins, with an upper layer moving along the wind direction (apart from the anti-cyclonic veering associated with the Coriolis force) and a bottom layer, thicker and slower than the upper one, moving along the opposite direction. The study has shown that water vertical mixing in the bay is inhibited by a large level of stable stratification, mainly associated with vertical variation in salinity and, to a minor extent, with temperature variation along the water column. More intense mixing, quantified by sub-critical values of the gradient Richardson number, is present in near-coastal regions where upwelling/downwelling phenomena occur. The analysis of instantaneous fields has detected the presence of

  1. An eddy-permitting oceanic general circulation model and its preliminary evaluation

    NASA Astrophysics Data System (ADS)

    Liu, Hailong; Zhang, Xuehong; Li, Wei; Yu, Yongqiang; Yu, Rucong

    2004-10-01

    An eddy-permitting, quasi-global oceanic general circulation model, LICOM (LASG/IAP (State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics) Climate System Ocean Model), with a uniform grid of 0.5° × 0.5° is established. Forced by wind stresses from Hellerman and Rosenstain (1983), a 40-yr integration is conducted with sea surface temperature and salinity being restored to the Levitus 94 datasets. The evaluation of the annual mean climatology of the LICOM control run shows that the large-scale circulation can be well reproduced. A comparison between the LICOM control run and a parallel integration of L30T63, which has the same framework but a coarse resolution, is also made to confirm the impact of resolution on the model performance. On account of the reduction of horizontal viscosity with the enhancement of the horizontal resolution, LICOM improves the simulation with respect to not only the intensity of the large scale circulations, but also the magnitude and structure of the Equatorial Undercurrent and South Equatorial Current. Taking advantage of the fine grid size, the pathway of the Indonesian Throughflow (ITF) is better represented in LICOM than in L30T63. The transport of ITF in LICOM is more convergent in the upper layer. As a consequence, the Indian Ocean tends to get warmer in LICOM. The poleward heat transports for both the global and individual basins are also significantly improved in LICOM. A decomposed analysis indicates that the transport due to the barotropic gyre, which primarily stands for the barotropic effect of the western boundary currents, plays a crucial role in making the difference.

  2. Albumin infusion may deleteriously promote extracellular fluid overload without improving circulating hypovolemia in patients of advanced cirrhosis with diabetes mellitus and sepsis.

    PubMed

    Kumar, Ramesh; Kumar, Sachin; Lata, Suman

    2013-04-01

    In patients with liver cirrhosis, albumin is given to improve relative hypovolemia caused by marked splanchnic arteriolar vasodilatation. However, the volume effect of albumin is not predictable and depends also on capillary permeability, hydrostatic pressure and lymphatic ability to re-circulate albumin from interstitium to plasma. In patients with decompensated cirrhosis, the capillary permeability is increased, hydrostatic pressure is higher, and the lymphatics functions are deficient. Hence the albumin molecules are more likely to be extravasated rapidly into the interstitium and are subsequently less likely to be re-circulated back into the plasma. This would not only fail to correct circulating hypovolemia, the purpose for which it is given, but also would favor development of reverse colloid oncotic pressure and fluid movement out of the capillaries leading to development of edema. Thus, anything else which could further increase capillary permeability or hydrostatic pressure in cirrhotic patients might create more problems with albumin infusion. An increased capillary permeability is the hallmark of diabetes mellitus. Furthermore, diabetes mellitus may worsen immunodepression in cirrhotic patients thus increasing the incidence of severe infections which may further have a deleterious effect on hemodynamics and capillary permeability. A diabetic patient with advanced cirrhosis and sepsis usually has markedly increased capillary permeability, high hydrostatic pressure due to hyperdynamic circulation, and compromised lymphatic drainage capacity. Hence, using albumin infusion in them would not only fail to improve relative hypovolemia, but also would deleteriously promote extravascular accumulation of fluid, which might impair the functions of many vital organs. However, the efficacy and safety of albumin infusion in diabetic patients with advanced cirrhosis and sepsis is not known. Such data can have a great clinical implication and would necessitate search of

  3. Preformed and regenerated phosphate in ocean general circulation models: can right total concentrations be wrong?

    NASA Astrophysics Data System (ADS)

    Duteil, O.; Koeve, W.; Oschlies, A.; Aumont, O.; Bianchi, D.; Bopp, L.; Galbraith, E.; Matear, R.; Moore, J. K.; Sarmiento, J. L.; Segschneider, J.

    2012-05-01

    Phosphate distributions simulated by seven state-of-the-art biogeochemical ocean circulation models are evaluated against observations of global ocean nutrient distributions. The biogeochemical models exhibit different structural complexities, ranging from simple nutrient-restoring to multi-nutrient NPZD type models. We evaluate the simulations using the observed volume distribution of phosphate. The errors in these simulated volume class distributions are significantly larger when preformed phosphate (or regenerated phosphate) rather than total phosphate is considered. Our analysis reveals that models can achieve similarly good fits to observed total phosphate distributions for a~very different partitioning into preformed and regenerated nutrient components. This has implications for the strength and potential climate sensitivity of the simulated biological carbon pump. We suggest complementing the use of total nutrient distributions for assessing model skill by an evaluation of the respective preformed and regenerated nutrient components.

  4. Preformed and regenerated phosphate in ocean general circulation models: can right total concentrations be wrong?

    NASA Astrophysics Data System (ADS)

    Duteil, O.; Koeve, W.; Oschlies, A.; Aumont, O.; Bianchi, D.; Bopp, L.; Galbraith, E.; Matear, R.; Moore, J. K.; Sarmiento, J. L.; Segschneider, J.

    2011-12-01

    Phosphate distributions simulated by seven state-of-the-art biogeochemical ocean circulation models are evaluated against observations of global ocean nutrient distributions. The biogeochemical models exhibit different structural complexities, ranging from simple nutrient-restoring to multi-nutrient NPZD type models. We evaluate the simulations using the observed volume distribution of phosphate. The errors in these simulated volume class distributions are significantly larger when preformed phosphate (or regenerated phosphate) rather than total phosphate is considered. Our analysis reveals that models can achieve similarly good fits to observed total phosphate distributions for a very different partitioning into preformed and regenerated nutrient components. This has implications for the strength and potential climate sensitivity of the simulated biological carbon pump. We suggest complementing the use of total nutrient distributions for assessing model skill by an evaluation of the respective preformed and regenerated nutrient components.

  5. Comparing the Degree of Land-Atmosphere Interaction in Four Atmospheric General Circulation Models

    NASA Technical Reports Server (NTRS)

    Koster, Randal D.; Dirmeyer, Paul A.; Hahmann, Andrea N.; Ijpelaar, Ruben; Tyahla, Lori; Cox, Peter; Suarez, Max J.; Houser, Paul R. (Technical Monitor)

    2001-01-01

    Land-atmosphere feedback, by which (for example) precipitation-induced moisture anomalies at the land surface affect the overlying atmosphere and thereby the subsequent generation of precipitation, has been examined and quantified with many atmospheric general circulation models (AGCMs). Generally missing from such studies, however, is an indication of the extent to which the simulated feedback strength is model dependent. Four modeling groups have recently performed a highly controlled numerical experiment that allows an objective inter-model comparison of land-atmosphere feedback strength. The experiment essentially consists of an ensemble of simulations in which each member simulation artificially maintains the same time series of surface prognostic variables. Differences in atmospheric behavior between the ensemble members then indicates the degree to which the state of the land surface controls atmospheric processes in that model. A comparison of the four sets of experimental results shows that feedback strength does indeed vary significantly between the AGCMs.

  6. Tracer water transport and subgrid precipitation variation within atmospheric general circulation models

    NASA Technical Reports Server (NTRS)

    Koster, Randal D.; Eagleson, Peter S.; Broecker, Wallace S.

    1988-01-01

    A capability is developed for monitoring tracer water movement in the three-dimensional Goddard Institute for Space Science Atmospheric General Circulation Model (GCM). A typical experiment with the tracer water model follows water evaporating from selected grid squares and determines where this water first returns to the Earth's surface as precipitation or condensate, thereby providing information on the lateral scales of hydrological transport in the GCM. Through a comparison of model results with observations in nature, inferences can be drawn concerning real world water transport. Tests of the tracer water model include a comparison of simulated and observed vertically-integrated vapor flux fields and simulations of atomic tritium transport from the stratosphere to the oceans. The inter-annual variability of the tracer water model results is also examined.

  7. Advanced Combustion Modeling for Complex Turbulent Flows

    NASA Technical Reports Server (NTRS)

    Ham, Frank Stanford

    2005-01-01

    The next generation of aircraft engines will need to pass stricter efficiency and emission tests. NASA's Ultra-Efficient Engine Technology (UEET) program has set an ambitious goal of 70% reduction of NO(x) emissions and a 15% increase in fuel efficiency of aircraft engines. We will demonstrate the state-of-the-art combustion tools developed a t Stanford's Center for Turbulence Research (CTR) as part of this program. In the last decade, CTR has spear-headed a multi-physics-based combustion modeling program. Key technologies have been transferred to the aerospace industry and are currently being used for engine simulations. In this demo, we will showcase the next-generation combustion modeling tools that integrate a very high level of detailed physics into advanced flow simulation codes. Combustor flows involve multi-phase physics with liquid fuel jet breakup, evaporation, and eventual combustion. Individual components of the simulation are verified against complex test cases and show excellent agreement with experimental data.

  8. A global multiscale mathematical model for the human circulation with emphasis on the venous system.

    PubMed

    Müller, Lucas O; Toro, Eleuterio F

    2014-07-01

    We present a global, closed-loop, multiscale mathematical model for the human circulation including the arterial system, the venous system, the heart, the pulmonary circulation and the microcirculation. A distinctive feature of our model is the detailed description of the venous system, particularly for intracranial and extracranial veins. Medium to large vessels are described by one-dimensional hyperbolic systems while the rest of the components are described by zero-dimensional models represented by differential-algebraic equations. Robust, high-order accurate numerical methodology is implemented for solving the hyperbolic equations, which are adopted from a recent reformulation that includes variable material properties. Because of the large intersubject variability of the venous system, we perform a patient-specific characterization of major veins of the head and neck using MRI data. Computational results are carefully validated using published data for the arterial system and most regions of the venous system. For head and neck veins, validation is carried out through a detailed comparison of simulation results against patient-specific phase-contrast MRI flow quantification data. A merit of our model is its global, closed-loop character; the imposition of highly artificial boundary conditions is avoided. Applications in mind include a vast range of medical conditions. Of particular interest is the study of some neurodegenerative diseases, whose venous haemodynamic connection has recently been identified by medical researchers.

  9. Reconciling the observed and modeled Southern Hemisphere circulation response to volcanic eruptions

    NASA Astrophysics Data System (ADS)

    McGraw, Marie C.; Barnes, Elizabeth A.; Deser, Clara

    2016-07-01

    Confusion exists regarding the tropospheric circulation response to volcanic eruptions, with models and observations seeming to disagree on the sign of the response. The forced Southern Hemisphere circulation response to the eruptions of Pinatubo and El Chichón is shown to be a robust positive annular mode, using over 200 ensemble members from 38 climate models. It is demonstrated that the models and observations are not at odds, but rather, internal climate variability is large and can overwhelm the forced response. It is further argued that the state of the El Niño-Southern Oscillation can at least partially explain the sign of the observed anomalies and may account for the perceived discrepancy between model and observational studies. The eruptions of both El Chichón and Pinatubo occurred during El Niño events, and it is demonstrated that the Southern Annular Mode anomalies following volcanic eruptions are weaker during El Niño events compared to La Niña events.

  10. High-Southern Latitudes Sulfur Cycle in an Atmospheric General Circulation Model

    NASA Astrophysics Data System (ADS)

    Cosme, E.; Genthon, C.; Martinerie, P.; Boucher, O.; Pham, M.

    2002-05-01

    This modeling study (Cosme et al., Sulfur cycle in the high southern latitudes in the LMD-ZT General Circulation Model, submitted to JGR) was motivated by the recent publication of annual time-scale records of dimethylsulfide (DMS) and dimethylsulfoxide (DMSO) in Antarctica, completing the available series of sulfate and methanesulfonic acid (MSA). Sulfur chemistry has been incorporated in the Laboratoire de Météorologie Dynamique Atmospheric General Circulation Model (AGCM), LMD-ZT, with high resolution and improved physics in the high-southern latitudes. The model predicts the concentration of 6 major sulfur species through emissions, transport, wet and dry deposition and chemistry in both gaseous and aqueous phases. Model results are broadly realistic when compared with measurements in air and snow or ice, and to results of other modeling studies, at high- and mid- southern latitudes. Although not corrected in this work, defects are identified and discussed: Atmospheric MSA concentrations are underestimated and DMSO concentrations are overestimated in summer, reflecting the lack of a DMSO sink leading to MSA; the deposition scheme used in the model may not be adapted to polar regions; DMS concentrations are underestimated in winter, and the model does not adequately reproduces interannual variability. Oceanic DMS sources appear deciding for the description of the sulfur cycle in these regions. The model suggests that ground atmospheric DMS concentrations are higher in winter than in summer, in a large part of central Antarctica. In the high-southern latitudes, high loads of DMS and DMSO are found and the main chemical sink of sulfur dioxide (SO2) is aqueous oxidation by ozone (O3), whereas oxidation by hydrogen peroxide (H2O2) dominates at the global scale.

  11. Advanced Modeling, Simulation and Analysis (AMSA) Capability Roadmap Progress Review

    NASA Technical Reports Server (NTRS)

    Antonsson, Erik; Gombosi, Tamas

    2005-01-01

    Contents include the following: NASA capability roadmap activity. Advanced modeling, simulation, and analysis overview. Scientific modeling and simulation. Operations modeling. Multi-special sensing (UV-gamma). System integration. M and S Environments and Infrastructure.

  12. Upper-Ocean Heat Balance Processes and the Walker Circulation in CMIP5 Model Projections

    NASA Technical Reports Server (NTRS)

    Robertson, F. R.; Roberts, J. B.; Funk, C.; Lyon, B.; Ricciardulli, L.

    2012-01-01

    Considerable uncertainty remains as to the importance of mechanisms governing decadal and longer variability of the Walker Circulation, its connection to the tropical climate system, and prospects for tropical climate change in the face of anthropogenic forcing. Most contemporary climate models suggest that in response to elevated CO2 and a warmer but more stratified atmosphere, the required upward mass flux in tropical convection will diminish along with the Walker component of the tropical mean circulation as well. Alternatively, there is also evidence to suggest that the shoaling and increased vertical stratification of the thermocline in the eastern Pacific will enable a muted SST increase there-- preserving or even enhancing some of the dynamical forcing for the Walker cell flow. Over the past decade there have been observational indications of an acceleration in near-surface easterlies, a strengthened Pacific zonal SST gradient, and globally-teleconnected dislocations in precipitation. But is this evidence in support of an ocean dynamical thermostat process posited to accompany anthropogenic forcing, or just residual decadal fluctuations associated with variations in warm and cold ENSO events and other stochastic forcing? From a modeling perspective we try to make headway on this question by examining zonal variations in surface energy fluxes and dynamics governing tropical upper ocean heat content evolution in the WCRP CMIP5 model projections. There is some diversity among model simulations; for example, the CCSM4 indicates net ocean warming over the IndoPacific region while the CSIRO model concentrates separate warming responses over the central Pacific and Indian Ocean regions. The models, as with observations, demonstrate strong local coupling between variations in column water vapor, downward surface longwave radiation and SST; but the spatial patterns of changes in the sign of this relationship differ among models and, for models as a whole, with

  13. Deterministic and Advanced Statistical Modeling of Wind-Driven Sea

    DTIC Science & Technology

    2015-07-06

    COVERED (From - To) 01/09/2010-06/07/2015 4. TITLE AND SUBTITLE Deterministic and advanced statistical modeling of wind-driven sea 5a. CONTRACT...Technical Report Deterministic and advanced statistical modeling of wind-driven sea Vladimir Zakharov, Andrei Pushkarev Waves and Solitons LLC, 1719 W...Development of accurate and fast advanced statistical and dynamical nonlinear models of ocean surface waves, based on first physical principles, which will

  14. Advances in Modelling of Valley Glaciers

    NASA Astrophysics Data System (ADS)

    Adhikari, Surendra

    For glaciological conditions typical of valley glaciers, the central idea of this research lies in understanding the effects of high-order mechanics and parameterizing these for simpler dynamical and statistical methods in glaciology. As an effective tool for this, I formulate a new brand of dynamical models that describes distinct physical processes of deformational flow. Through numerical simulations of idealized glacier domains, I calculate empirical correction factors to capture the effects of longitudinal stress gradients and lateral drag for simplified dynamical models in the plane-strain regime. To get some insights into real glacier dynamics, I simulate Haig Glacier in the Canadian Rocky Mountains. As geometric effects overshadow dynamical effects in glacier retreat scenarios, it appears that high-order physics are not very important for Haig Glacier, particularly for evaluating its fate. Indeed, high-order and reduced models all predict that Haig Glacier ceases to exist by about AD2080 under ongoing climate warming. This finding regarding the minimal role of high-order physics may not be broadly valid, as it is not true in advance scenarios at Haig Glacier and it may not be representative of other glaciological settings. Through a 'bulk' parameterization of high-order physics, geometric and climatic settings, sliding conditions, and transient effects, I also provide new insights into the volume-area relation, a widely used statistical method for estimating glacier volume. I find a steady-state power-law exponent of 1:46, which declines systematically to 1:38 after 100 years of sustained retreat, in good accord with the observations. I recommend more accurate scaling relations through characterization of individual glacier morphology and degree of climatic disequilibrium. This motivates a revision of global glacier volume estimates, of some urgency in sea level rise assessments.

  15. Two-Layer Variable Infiltration Capacity Land Surface Representation for General Circulation Models

    NASA Technical Reports Server (NTRS)

    Xu, L.

    1994-01-01

    A simple two-layer variable infiltration capacity (VIC-2L) land surface model suitable for incorporation in general circulation models (GCMs) is described. The model consists of a two-layer characterization of the soil within a GCM grid cell, and uses an aerodynamic representation of latent and sensible heat fluxes at the land surface. The effects of GCM spatial subgrid variability of soil moisture and a hydrologically realistic runoff mechanism are represented in the soil layers. The model was tested using long-term hydrologic and climatalogical data for Kings Creek, Kansas to estimate and validate the hydrological parameters. Surface flux data from three First International Satellite Land Surface Climatology Project Field Experiments (FIFE) intensive field compaigns in the summer and fall of 1987 in central Kansas, and from the Anglo-Brazilian Amazonian Climate Observation Study (ABRACOS) in Brazil were used to validate the mode-simulated surface energy fluxes and surface temperature.

  16. Simulating Titan’s tropospheric circulation with the Portable University Model of the Atmosphere

    NASA Astrophysics Data System (ADS)

    Grieger, B.; Segschneider, J.; Keller, H. U.; Rodin, A. V.; Lunkeit, F.; Kirk, E.; Fraedrich, K.

    2004-01-01

    The Portable University Model of the Atmosphere (PUMA) is a general circulation model of intermediate complexity. In the model setup used herein, the dynamics is driven by restoration to a prescribed temperature field. Given an observed three-dimensional field of restoration temperatures, the feedback of aerosol distribution to the radiation scheme and hence to the dynamics is excluded from calculations. PUMA is adapted to Titan conditions and used to carry out a series of experiments with temperature fields based on radio occultation and infrared spectroscopy measurements taken by Voyager 1 in 1980. The resultant winds are prograde with maximum wind speeds of about 14 m/s in the troposphere. This simulation demonstrates capabilities of a restricted complexity model and provides a contribution to the prediction of the descent trajectory of the Huygens lander in January 2005.

  17. Modified graphical autocatalytic set model of combustion process in circulating fluidized bed boiler

    NASA Astrophysics Data System (ADS)

    Yusof, Nurul Syazwani; Bakar, Sumarni Abu; Ismail, Razidah

    2014-07-01

    Circulating Fluidized Bed Boiler (CFB) is a device for generating steam by burning fossil fuels in a furnace operating under a special hydrodynamic condition. Autocatalytic Set has provided a graphical model of chemical reactions that occurred during combustion process in CFB. Eight important chemical substances known as species were represented as nodes and catalytic relationships between nodes are represented by the edges in the graph. In this paper, the model is extended and modified by considering other relevant chemical reactions that also exist during the process. Catalytic relationship among the species in the model is discussed. The result reveals that the modified model is able to gives more explanation of the relationship among the species during the process at initial time t.

  18. Modeling of thermohydraulic transients in a boiling helium natural circulation loop

    NASA Astrophysics Data System (ADS)

    Furci, H.; Baudouy, B.

    2016-12-01

    Boiling helium natural circulation loops are a cooling option for superconducting magnets. Previous studies on the field have provided a thorough understanding of their steady state behavior in all boiling regimes. Recent experimental research has lead to the understanding of their transient behavior. In particular, it highlights the impact of the thermohydraulic evolution of the circuit on the onset of transient boiling crisis, which represents a limitation of the cooling system. Hence, the need of modeling this aspect of these systems. In this work we present modeling options of two-phase helium loops departing from the homogeneous equilibrium two-phase flow model. Reasonable additional assumptions are introduced to obtain a simplified model and the effect of these assumptions is evaluated by comparison with the solution of the non-simplified equations system. These methods are compared to experimental data to analyze their success and limitations.

  19. Study of hydrogasdynamic processes using a cold model for a circulation degassing unit

    NASA Astrophysics Data System (ADS)

    Yurov, A. V.; Chuikov, F. V.; Kominov, S. V.; Semin, A. E.

    2014-12-01

    The processes of interaction of a transporting gas with a liquid during circulation degassing are studied using cold modeling. An experimental technique is developed using the modern methods of obtaining information, digital technologies, computer vision, and computer analysis of experimental data. The change of the area of the liquid-gas interface surface is found as a function of the transporting gas flow rate, and a technique is determined to estimate the time of averaging the liquid composition. Similarity criteria are determined to compare the investigation results with the data obtained on real units.

  20. Parallel algorithms for semi-Lagrangian transport in global atmospheric circulation models

    SciTech Connect

    Drake, J.B.; Worley, P.H.; Michalakes, J.; Foster, I.T.

    1995-02-01

    Global atmospheric circulation models (GCM) typically have three primary algorithmic components: columnar physics, spectral transform, and semi-Lagrangian transport. In developing parallel implementations, these three components are equally important and can be examined somewhat independently. A two-dimensional horizontal data decomposition of the three-dimensional computational grid leaves all physics computations on processor, and the only efficiency issues arise in load balancing. A recently completed study by the authors of different approaches to parallelizing the spectral transform showed several viable algorithms. Preliminary results of an analogous study of algorithmic alternatives for parallel semi-Lagrangian transport are described here.

  1. Mars atmospheric dynamics as simulated by the NASA AMES General Circulation Model. II - Transient baroclinic eddies

    NASA Astrophysics Data System (ADS)

    Barnes, J. R.; Pollack, J. B.; Haberle, R. M.; Leovy, C. B.; Zurek, R. W.; Lee, H.; Schaeffer, J.

    1993-02-01

    A large set of experiments performed with the NASA Ames Mars General Circulation Model is analyzed to determine the properties, structure, and dynamics of the simulated transient baroclinic eddies. There is strong transient baroclinic eddy activity in the extratropics of the Northern Hemisphere during the northern autumn, winter, and spring seasons. The eddy activity remains strong for very large dust loadings, though it shifts northward. The eastward propagating eddies are characterized by zonal wavenumbers of 1-4 and periods of about 2-10 days. The properties of the GCM baroclinic eddies in the northern extratropics are compared in detail with analogous properties inferred from Viking Lander meteorology observations.

  2. Cloud-radiative effects on implied oceanic energy transports as simulated by atmospheric general circulation models

    SciTech Connect

    Gleckler, P.J.; Randall, D.A.; Boer, G.

    1994-03-01

    This paper reports on energy fluxes across the surface of the ocean as simulated by fifteen atmospheric general circulation models in which ocean surface temperatures and sea-ice boundaries are prescribed. The oceanic meridional energy transport that would be required to balance these surface fluxes is computed, and is shown to be critically sensitive to the radiative effects of clouds, to the extent that even the sign of the Southern Hemisphere ocean energy transport can be affected by the errors in simulated cloud-radiation interactions.

  3. Computational design of the basic dynamical processes of the UCLA general circulation model

    NASA Technical Reports Server (NTRS)

    Arakawa, A.; Lamb, V. R.

    1977-01-01

    The 12-layer UCLA general circulation model encompassing troposphere and stratosphere (and superjacent 'sponge layer') is described. Prognostic variables are: surface pressure, horizontal velocity, temperature, water vapor and ozone in each layer, planetary boundary layer (PBL) depth, temperature, moisture and momentum discontinuities at PBL top, ground temperature and water storage, and mass of snow on ground. Selection of space finite-difference schemes for homogeneous incompressible flow, with/without a free surface, nonlinear two-dimensional nondivergent flow, enstrophy conserving schemes, momentum advection schemes, vertical and horizontal difference schemes, and time differencing schemes are discussed.

  4. Orthotopic mouse models of tumor metastasis expressing fluorescent reporters produce imageable circulating tumor cells.

    PubMed

    Hoffman, Robert M

    2014-12-01

    Circulating tumor cells (CTC) are of high importance, since they are potential metastatic precursors and are readily available for prognostic analysis and treatment testing. In this review, we demonstrate the great power that green fluorescent protein (GFP) labeling and orthotopic mouse models of cancer confer to the study of CTCs for isolation and characterization, including metastatic testing in mice and the chick embryo as well as drug response testing in vitro. We also describe a facile method to label patient CTCs ex vivo using a telomerase-expressing GFP-containing adenovirus that will allow the CTC studies described in this review to be translated clinically.

  5. Upper Boundary Extension of the NASA Ames Mars General Circulation Model

    NASA Technical Reports Server (NTRS)

    Brecht, Amanda S.; Hollingsworth, J. L.; Kahre, M. A.; Schaeffer, J. R.

    2012-01-01

    Extending the NASA Ames Mars General Circulation Model (MGCM) upper boundary will expand our understanding of the connection between the lower and upper atmosphere of Mars through the middle atmosphere. The extension's main requirements is incorporation of Non-local thermodynamic equilibrium (NLTE) heating (visible) and cooling (infrared). NLTE occurs when energy is exchanged more rapidly with the radiation field (or other energy sources) rather than collisions with other molecules. Without NLTE above approximately 80km/approximately 60km in Mars' atmosphere the IR/visible heating rates are overestimated. Currently NLTE has been applied successfully into the 1D RT code and is in progress for the 3D application.

  6. Discussion on climate oscillations: CMIP5 general circulation models versus a semi-empirical harmonic model based on astronomical cycles

    NASA Astrophysics Data System (ADS)

    Scafetta, Nicola

    2013-11-01

    Power spectra of global surface temperature (GST) records (available since 1850) reveal major periodicities at about 9.1, 10-11, 19-22 and 59-62 years. Equivalent oscillations are found in numerous multisecular paleoclimatic records. The Coupled Model Intercomparison Project 5 (CMIP5) general circulation models (GCMs), to be used in the IPCC Fifth Assessment Report (AR5, 2013), are analyzed and found not able to reconstruct this variability. In particular, from 2000 to 2013.5 a GST plateau is observed while the GCMs predicted a warming rate of about 2 °C/century. In contrast, the hypothesis that the climate is regulated by specific natural oscillations more accurately fits the GST records at multiple time scales. For example, a quasi 60-year natural oscillation simultaneously explains the 1850-1880, 1910-1940 and 1970-2000 warming periods, the 1880-1910 and 1940-1970 cooling periods and the post 2000 GST plateau. This hypothesis implies that about 50% of the ~ 0.5 °C global surface warming observed from 1970 to 2000 was due to natural oscillations of the climate system, not to anthropogenic forcing as modeled by the CMIP3 and CMIP5 GCMs. Consequently, the climate sensitivity to CO2 doubling should be reduced by half, for example from the 2.0-4.5 °C range (as claimed by the IPCC, 2007) to 1.0-2.3 °C with a likely median of ~ 1.5 °C instead of ~ 3.0 °C. Also modern paleoclimatic temperature reconstructions showing a larger preindustrial variability than the hockey-stick shaped temperature reconstructions developed in early 2000 imply a weaker anthropogenic effect and a stronger solar contribution to climatic changes. The observed natural oscillations could be driven by astronomical forcings. The ~ 9.1 year oscillation appears to be a combination of long soli-lunar tidal oscillations, while quasi 10-11, 20 and 60 year oscillations are typically found among major solar and heliospheric oscillations driven mostly by Jupiter and Saturn movements. Solar models based

  7. A study of eddy-mean flow interactions using Eliassen-Palm diagnostics: FGGE SOP-1 data and the NASA GLAS general circulation model compared

    NASA Technical Reports Server (NTRS)

    Baldwin, M. P.; Edmon, H. J., Jr.; Holton, J. R.

    1984-01-01

    Latitude-height cross sections of the Eliassen-Palm (ep) flux, its divergence, the residual mean meridional circulation as well as conventional eddy and mean flow fields are computed using both observational and general circulation model data.

  8. Technical Report Series on Global Modeling and Data Assimilation. Volume 16; Filtering Techniques on a Stretched Grid General Circulation Model

    NASA Technical Reports Server (NTRS)

    Takacs, Lawrence L.; Sawyer, William; Suarez, Max J. (Editor); Fox-Rabinowitz, Michael S.

    1999-01-01

    This report documents the techniques used to filter quantities on a stretched grid general circulation model. Standard high-latitude filtering techniques (e.g., using an FFT (Fast Fourier Transformations) to decompose and filter unstable harmonics at selected latitudes) applied on a stretched grid are shown to produce significant distortions of the prognostic state when used to control instabilities near the pole. A new filtering technique is developed which accurately accounts for the non-uniform grid by computing the eigenvectors and eigenfrequencies associated with the stretching. A filter function, constructed to selectively damp those modes whose associated eigenfrequencies exceed some critical value, is used to construct a set of grid-spaced weights which are shown to effectively filter without distortion. Both offline and GCM (General Circulation Model) experiments are shown using the new filtering technique. Finally, a brief examination is also made on the impact of applying the Shapiro filter on the stretched grid.

  9. Mixed boundary conditions in ocean general circulation models and their influence on the stability of the model`s conveyor belt

    SciTech Connect

    Mikolajewicz, U.; Maier-reimer, E.

    1994-11-01

    When driven under `mixed boundary conditions` coarse resolution ocean general circulation models (OGCMs) generally show a high sensitivity of the present-day thermohaline circulation against perturbations. We will show that an alternative formulation of the boundary condition for temperature, a mixture of prescribed heat fluxes and additional restoring of the sea surface temperature to a climatological boundary temperature with a longer time constant, drastically alters the stability of the modes of the thermohaline circulation. The results from simulations with the Hamburg large-scale geostrophic OGCM indicate that the stability of the mode of the thermohaline circulation with formation of North Atlantic deepwater increases, if the damping of sea surface temperature anomalies is reduced, whereas the opposite is true for the mode without North Atlantic deep water formation. It turns out that the formulation of the temperature boundary condition also affects the variability of the model.

  10. Effects of wave-induced forcing on a circulation model of the North Sea

    NASA Astrophysics Data System (ADS)

    Staneva, Joanna; Alari, Victor; Breivik, Øyvind; Bidlot, Jean-Raymond; Mogensen, Kristian

    2017-01-01

    The effect of wind waves on water level and currents during two storms in the North Sea is investigated using a high-resolution Nucleus for European Modelling of the Ocean (NEMO) model forced with fluxes and fields from a high-resolution wave model. The additional terms accounting for wave-current interaction that are considered in this study are the Stokes-Coriolis force, the sea-state-dependent energy and momentum fluxes. The individual and collective role of these processes is quantified and the results are compared with a control run without wave effects as well as against current and water-level measurements from coastal stations. We find a better agreement with observations when the circulation model is forced by sea-state-dependent fluxes, especially in extreme events. The two extreme events, the storm Christian (25-27 October 2013), and about a month later, the storm Xaver (5-7 December 2013), induce different wave and surge conditions over the North Sea. Including the wave effects in the circulation model for the storm Xaver raises the modelled surge by more than 40 cm compared with the control run in the German Bight area. For the storm Christian, a difference of 20-30 cm in the surge level between the wave-forced and the stand-alone ocean model is found over the whole southern part of the North Sea. Moreover, the modelled vertical velocity profile fits the observations very well when the wave forcing is accounted for. The contribution of wave-induced forcing has been quantified indicating that this represents an important mechanism for improving water-level and current predictions.

  11. Snowline instability in a general circulation model: application to Carboniferous glaciation

    SciTech Connect

    Crowley, T.J.; Yip, Kuor-Kier, J.; Baum, S.K.

    1994-11-01

    For over twenty years it has been known that energy balance models (EBMs) with snow-albedo feedback are characterized by unstable behavior in some areas of parameter space. This behaviour leads to rapid changes in snow area due to small changes in forcing, and has been termed the small ice cap instability (SICI). It has never been clarified whether this behaviour reflects a real feature of the climate system or a limitation in EBMs. In this study we demonstrate that evidence for similar unstable behavior can also be found in an atmospheric general circulation model (GCM), using a realistic set of boundary conditions for the Carboniferous (300 Ma), one of the most extensive periods of glaciation in Earth history. When solar luminosity is sequentially lowered to near values appropriate for the Carboniferous, there is a discontinuous increase in summer snow area. The instability occurs in approximately the same area of parameter space as one previously found in an EBM. Analysis of selected fields indicates that the circulation is primarily affected in the area of snow increase; far-field effects are minimal. There is good agreement between model-generated summer snowcover and one reconstruction of Carboniferous ice cover. Although more work is required on this topic, our results provide increased support for the possibility that the snowline instability represents a real feature of the climate system, and that it may help explain some cases of glacial inception and abrupt transitions in Earth history. 63 refs., 20 figs.

  12. Integrated cumulus ensemble and turbulence (ICET): An integrated parameterization system for general circulation models (GCMs)

    SciTech Connect

    Evans, J.L.; Frank, W.M.; Young, G.S.

    1996-04-01

    Successful simulations of the global circulation and climate require accurate representation of the properties of shallow and deep convective clouds, stable-layer clouds, and the interactions between various cloud types, the boundary layer, and the radiative fluxes. Each of these phenomena play an important role in the global energy balance, and each must be parameterized in a global climate model. These processes are highly interactive. One major problem limiting the accuracy of parameterizations of clouds and other processes in general circulation models (GCMs) is that most of the parameterization packages are not linked with a common physical basis. Further, these schemes have not, in general, been rigorously verified against observations adequate to the task of resolving subgrid-scale effects. To address these problems, we are designing a new Integrated Cumulus Ensemble and Turbulence (ICET) parameterization scheme, installing it in a climate model (CCM2), and evaluating the performance of the new scheme using data from Atmospheric Radiation Measurement (ARM) Program Cloud and Radiation Testbed (CART) sites.

  13. Analog electrical model of the coronary circulation in case of multiple revascularizations.

    PubMed

    Maasrani, Mahmoud; Verhoye, Jean-Philippe; Corbineau, Herve; Drochon, Agnes

    2008-07-01

    In this work, we propose an analog electrical model of the coronary circulation for patients with obstructive disease undergoing revascularization. In this clinical situation, the collateral circulation to the occluded artery is difficult to ascertain via preoperative measurements and well-developed collaterals might induce long-term restenosis of the revascularized artery due to flow competition mechanisms. The proposed model allows an original biomechanical analysis of per-operative hemodynamic data in order to assess quantitative evaluation of pressures and flows inside the native stenosed arteries, the collateral network and the bypass grafts. Average cardiac cycle values are analysed. In the case of 3-vessel disease and chronic occlusion of the right coronary artery, the quantitative results confirm the protective effects of the collateral flows in the pathological situation, but also show that the revascularization of the occluded right artery is fully justified since the collateral flows remain low, even when the left territory is revascularized. The model thus provides a computational tool to evaluate therapeutic strategies for each patient.

  14. Improved short-term variability in the thermosphere-ionosphere-mesosphere-electrodynamics general circulation model

    NASA Astrophysics Data System (ADS)

    Häusler, K.; Hagan, M. E.; Baumgaertner, A. J. G.; Maute, A.; Lu, G.; Doornbos, E.; Bruinsma, S.; Forbes, J. M.; Gasperini, F.

    2014-08-01

    We report on a new source of tidal variability in the National Center for Atmospheric Research thermosphere-ionosphere-mesosphere-electrodynamics general circulation model (TIME-GCM). Lower boundary forcing of the TIME-GCM for a simulation of November-December 2009 based on 3-hourly Modern-Era Retrospective Analysis for Research and Application (MERRA) reanalysis data includes day-to-day variations in both diurnal and semidiurnal tides of tropospheric origin. Comparison with TIME-GCM results from a heretofore standard simulation that includes climatological tropospheric tides from the global-scale wave model reveal evidence of the impacts of MERRA forcing throughout the model domain, including measurable tidal variability in the TIME-GCM upper thermosphere. Additional comparisons with measurements made by the Gravity field and steady-state Ocean Circulation Explorer satellite show improved TIME-GCM capability to capture day-to-day variations in thermospheric density for the November-December 2009 period with the new MERRA lower boundary forcing.

  15. Assimilation of geodetic dynamical ocean topography data into ocean circulation model

    NASA Astrophysics Data System (ADS)

    Janjic, Tijana; Schroeter, Jens; Albertella, Alberta; Bosch, Wolfgang; Rummel, Reiner; Savcenko, Roman

    Estimation of ocean circulation via assimilation of satellite measurements of dynamical ocean topography (DOT) into the global finite-element ocean model (FEOM) is investigated. The DOT was obtained by means of geodetic approach from carefully cross-calibrated multi-mission-altimeter data and GRACE gravity fields. The spectral consistency was achieved by means of the filtering applied on sea surface and geoid. Since the dynamical ocean topography is obtained from data types coming from different sources, different techniques can be employed for their assimilation into ocean circulation models. For example, the data can be combined and interpolated onto the model grid before they are used in assimilation. In this case special care needs to be taken concerning the specification of observational error statistics. The assimilation is performed by employing the local SEIK filter and various functions for observations error covariance are used. Finally we consider the effects of assimilation on potential temperature field and on steric height changes. Analysed potential temperature is compared with ARGO data. We also compared the standard deviation of the observations and standard deviation of the steric height calculated from the analysis. In many regions of the world ocean there is a good correspondence between these two fields. However also structures that are not present in the observations appear in the steric height standard deviations. Keywords: dynamical ocean topography, data assimilation Session: A2.6

  16. Constraining a Martian general circulation model with the MAVEN/IUVS observations in the thermosphere

    NASA Astrophysics Data System (ADS)

    Moeckel, Chris; Medvedev, Alexander; Nakagawa, Hiromu; Evans, Scott; Kuroda, Takeshi; Hartogh, Paul; Yiğit, Erdal; Jain, Sonal; Lo, Daniel; Schneider, Nicholas M.; Jakosky, Bruce

    2016-10-01

    The recent measurements of the number density of atomic oxygen by Mars Atmosphere and Volatile EvolutioN/ Imaging UltraViolet Spectrograph (MAVEN/IUVS) have been implemented for the first time into a global circulation model to quantify the effect on the Martian thermosphere. The number density has been converted to 1D volume mixing ratio and this profile is compared to the atomic oxygen scenarios based on chemical models. Simulations were performed with the Max Planck Institute Martian General Circulation Model (MPI-MGCM). The simulations closely emulate the conditions at the time of observations. The results are compared to the IUVS-measured CO2 number density and temperature above 130 km to gain knowledge of the processes in the upper atmosphere and further constrain them in MGCMs. The presentation will discuss the role and importance in the thermosphere of the following aspects: (a) impact of the observed atomic oxygen, (b) 27-day solar cycle variations, (c) varying dust load in the lower atmosphere, and (d) gravity waves.

  17. Model representation of salinity anomalies and the stability of the North Atlantic overturning circulation

    NASA Astrophysics Data System (ADS)

    Megann, A.; New, A.; Blaker, A.

    2012-04-01

    Vellinga and Wu (2004) and others have identified feedback cycles governing the decadal variability of the North Atlantic overturning circulation, in which modulation of tropical rainfall creates near-surface salinity anomalies that propagate northward to the winter convection regions, where they affect the wintertime convection through changes in surface density. Freshwater "hosing" experiments, in which 0.1 Sv of extra freshwater is added to the convection region, are described using two climate models: the UK Met Office's HadCM3; and CHIME, which is identical to HadCM3 except for the replacement of the z-coordinate ocean component of HadCM3 with the hybrid isopycnic model HYCOM. While HadCM3 shows an unambiguous weakening of the meridional overturning circulation (MOC) by 5 Sv, the MOC in CHIME initially starts to decrease but returns to a value close to that in the control experiment after 40-50 years even though the hosing flux is still being applied. It will be shown that the recovery of the overturning in CHIME is mainly due to enhanced advective transport of salt from the subtropics by salinity anomalies. These are found to be substantially more coherent meridionally in CHIME than in HadCM3, consistent with the known superior ability of the isopycnic model formulation to preserve watermass properties over long distances.

  18. Tidally averaged circulation in Puget Sound sub-basins: Comparison of historical data, analytical model, and numerical model

    SciTech Connect

    Khangaonkar, Tarang; Yang, Zhaoqing; Kim, Tae Yun; Roberts, Mindy

    2011-07-20

    Through extensive field data collection and analysis efforts conducted since the 1950s, researchers have established an understanding of the characteristic features of circulation in Puget Sound. The pattern ranges from the classic fjordal behavior in some basins, with shallow brackish outflow and compensating inflow immediately below, to the typical two-layer flow observed in many partially mixed estuaries with saline inflow at depth. An attempt at reproducing this behavior by fitting an analytical formulation to past data is presented, followed by the application of a three-dimensional circulation and transport numerical model. The analytical treatment helped identify key physical processes and parameters, but quickly reconfirmed that response is complex and would require site-specific parameterization to include effects of sills and interconnected basins. The numerical model of Puget Sound, developed using unstructured-grid finite volume method, allowed resolution of the sub-basin geometric features, including presence of major islands, and site-specific strong advective vertical mixing created by bathymetry and multiple sills. The model was calibrated using available recent short-term oceanographic time series data sets from different parts of the Puget Sound basin. The results are compared against (1) recent velocity and salinity data collected in Puget Sound from 2006 and (2) a composite data set from previously analyzed historical records, mostly from the 1970s. The results highlight the ability of the model to reproduce velocity and salinity profile characteristics, their variations among Puget Sound subbasins, and tidally averaged circulation. Sensitivity of residual circulation to variations in freshwater inflow and resulting salinity gradient in fjordal sub-basins of Puget Sound is examined.

  19. Sensitivity of modeled estuarine circulation to spatial and temporal resolution of input meteorological forcing of a cold frontal passage

    NASA Astrophysics Data System (ADS)

    Weaver, Robert J.; Taeb, Peyman; Lazarus, Steven; Splitt, Michael; Holman, Bryan P.; Colvin, Jeffrey

    2016-12-01

    In this study, a four member ensemble of meteorological forcing is generated using the Weather Research and Forecasting (WRF) model in order to simulate a frontal passage event that impacted the Indian River Lagoon (IRL) during March 2015. The WRF model is run to provide high and low, spatial (0.005° and 0.1°) and temporal (30 min and 6 h) input wind and pressure fields. The four member ensemble is used to force the Advanced Circulation model (ADCIRC) coupled with Simulating Waves Nearshore (SWAN) and compute the hydrodynamic and wave response. Results indicate that increasing the spatial resolution of the meteorological forcing has a greater impact on the results than increasing the temporal resolution in coastal systems like the IRL where the length scales are smaller than the resolution of the operational meteorological model being used to generate the forecast. Changes in predicted water elevations are due in part to the upwind and downwind behavior of the input wind forcing. The significant wave height is more sensitive to the meteorological forcing, exhibited by greater ensemble spread throughout the simulation. It is important that the land mask, seen by the meteorological model, is representative of the geography of the coastal estuary as resolved by the hydrodynamic model. As long as the temporal resolution of the wind field captures the bulk characteristics of the frontal passage, computational resources should be focused so as to ensure that the meteorological model resolves the spatial complexities, such as the land-water interface, that drive the land use responsible for dynamic downscaling of the winds.

  20. Explicit entrainment parameterization in the general circulation model ECHAM5-HAM

    NASA Astrophysics Data System (ADS)

    Siegenthaler-Le Drian, Colombe; Spichtinger, Peter; Lohmann, Ulrike

    2010-05-01

    The complex interactions affecting cloud lifetime and liquid water path (LWP) are not well captured in state-of-the-art general circulation models (GCM). A recent climate model intercomparison showed an overestimation of the positive correlation of LWP with aerosol optical depth by a factor of two as compared to MODIS data for almost all participating models (Quaas et al., 2009). As the authors suggest, a proper interaction of the boundary layer dynamics, particularly the inclusion of cloud top entrainment may lead to an improvement. ECHAM5 was one of the participating model. In this model, the turbulent fluxes in the planetary boundary layer are simulated using a turbulent kinetic energy - mixing length scheme. It has been showed that its performance diminishes when the resolution decreases, the different fluxes being not represented satisfactory with 31 vertical levels, particularly at the cloud top (Lenderink et al., 2000). We thus replace the turbulent fluxes by the explicit entrainment closure by Turton and Nicholls (1987) at the top of the stratocumulus capped boundary layers. The turbulent fluxes are weighted with the cloud cover to apply the entrainment closure only above clouds. In addition, we use an explicit term for the radiative cooling contribution in the buoyancy production term. We use the new version of the Hamburg general circulation model ECHAM5-HAM (Roeckner et al., 2003; Stier et al., 2005). The cloud scheme that is used for this study includes the double-moment cloud microphysics scheme for cloud droplets and ice crystals (Lohmann et al., 2007). The principal effect of the explicit entrainment is to dry and warm the planetary boundary layer. The averaged profiles are more stable and the inversion is reduced. The stratocumulus deck is reduced in all typical stratocumulus regions. In a single column version of the model, the diurnal cycle simulated in cloud cover or equivalentely in cloud water is much more representative of observed subtropical

  1. Oxygen supply to the fetal cerebral circulation in hypoplastic left heart syndrome: a simulation study based on the theoretical models of fetal circulation.

    PubMed

    Sakazaki, Sayaka; Masutani, Satoshi; Sugimoto, Masaya; Tamura, Masanori; Kuwata, Seiko; Kurishima, Clara; Saiki, Hirofumi; Iwamoto, Yoichi; Ishido, Hirotaka; Senzaki, Hideaki

    2015-03-01

    Hypoxia due to congenital heart diseases (CHDs) adversely affects brain development during the fetal period. Head circumference at birth is closely associated with neuropsychiatric development, and it is considerably smaller in newborns with hypoplastic left heart syndrome (HLHS) than in normal newborns. We performed simulation studies on newborns with CHD to evaluate the cerebral circulation during the fetal period. The oxygen saturation of cerebral blood flow in newborns with CHD was simulated according to a model for normal fetal circulation in late pregnancy. We compared the oxygen saturation of cerebral blood flow between newborns with tricuspid atresia (TA; a disease showing univentricular circulation and hypoplasia of the right ventricle), those with transposition of the great arteries (TGA; a disease showing abnormal mixing of arterial and venous blood), and those with HLHS. The oxygen saturation of cerebral blood flow in newborns with normal circulation was 75.7 %, whereas it was low (49.5 %) in both newborns with HLHS and those with TA. Although the oxygen level is affected by the blood flow through the foramen ovale, the oxygen saturation in newborns with TGA was even lower (43.2 %). These data, together with previous reports, suggest that the cerebral blood flow rate is decreased in newborns with HLHS, and the main cause was strongly suspected to be retrograde cerebral perfusion through a patent ductus arteriosus. This study provides important information about the neurodevelopmental prognosis of newborns with HLHS and suggests the need to identify strategies to resolve this unfavorable cerebral circulatory state in utero.

  2. Idealized Land-sea Warming Contrast Experiments with Two Global Circulation Models: Preliminary results

    NASA Astrophysics Data System (ADS)

    Kim, J. E. E.; Lee, J. L.; Hong, S. Y.

    2014-12-01

    Simulations of warming climates with climate models have pointed out that land surface temperatures will increase more rapidly than sea surface temperature (SST), which is known as the "land-sea warming contrast". We investigate the response of a zonally symmetric atmosphere to robust land-sea surface warming contrast using two global circulation models (GCMs): Non-hydrostatic Icosahedral Model (NIM) and Global and Regional Integrated Model system (GRIMs). NIM is a Finite-volume icosahedral model developed as a next-generation operational model at National Oceanic and Atmospheric Administration Earth System Research Laboratory (NOAA ESRL). Full model physics were taken from Model for Prediction Across Scales (MPAS) physics suite. GRIMs is a spectral model which has been developed in Korea (Hong et al., 2013, APJAS). It has flexibility for selection of comparable physics options with NIM. Two sets of experiments are designed: one is the control experiment with zonally-symmetric distributions with maxima at the equator and varying off-equatorial temperature gradients on ocean and land. The other experiment will impose the land/sea warming ratio of 1.5. Since two models can be set up with identical physics parameterizations, general consensus on responses and model-dependent feedback can be suggested.

  3. Coupled ice-flow/ocean circulation modeling in the Amundsen Sea Embayment using ISSM and MITgcm.

    NASA Astrophysics Data System (ADS)

    Larour, E. Y.; Menemenlis, D.; Schodlok, M.

    2014-12-01

    the West Antarctic Ice Sheet is thought to be prone to marine instability in which prolonged grounding line retreat could occur due to inland downwards sloping bedrocks. However, this instability is difficult to model in part due to the absence of good parameterizations for melt-rates under ice-shelves, in particular near or at the grounding-line, where a complex interplay between butressing, melt-rate, water-pressure and internal stresses in the ice develops. In order to simulate such melt rates accurately, ice-sheet models need to be fully coupled to ocean models, in order to capture the feedback mechanisms between heat-flux at the ice/ocean interface and cavity shape driven by grounding-line retreat.Here, we show an example of such a coupling between the Ice Sheet System Model (ISSM) and the MIT General Circulation Model (MITgcm). The goal is to run sensitivity studies of the evolution of Pine Island Glacier in West Antarctica. We quantify the impact of feedbacks between both systems by running short transients (20-100 years) of the coupled ice-sheet flow/ocean circulation model. We vary inputs such as far-field temperature of the Circumpolar Deep-Water, surface temperature of the Amundsen Sea Embayment, and far-field surface ice-flow velocity. Preliminary insights into the variability of the system are presented, as well as quantified impacts of variations in model inputs.This work was performed at the California Institute of Technology's Jet Propulsion Laboratory undera contract with the National Aeronautics and Space Administration's Cryosphere Science Program.

  4. Using Green's Functions to initialize and adjust a global, eddying ocean biogeochemistry general circulation model

    NASA Astrophysics Data System (ADS)

    Brix, H.; Menemenlis, D.; Hill, C.; Dutkiewicz, S.; Jahn, O.; Wang, D.; Bowman, K.; Zhang, H.

    2015-11-01

    The NASA Carbon Monitoring System (CMS) Flux Project aims to attribute changes in the atmospheric accumulation of carbon dioxide to spatially resolved fluxes by utilizing the full suite of NASA data, models, and assimilation capabilities. For the oceanic part of this project, we introduce ECCO2-Darwin, a new ocean biogeochemistry general circulation model based on combining the following pre-existing components: (i) a full-depth, eddying, global-ocean configuration of the Massachusetts Institute of Technology general circulation model (MITgcm), (ii) an adjoint-method-based estimate of ocean circulation from the Estimating the Circulation and Climate of the Ocean, Phase II (ECCO2) project, (iii) the MIT ecosystem model "Darwin", and (iv) a marine carbon chemistry model. Air-sea gas exchange coefficients and initial conditions of dissolved inorganic carbon, alkalinity, and oxygen are adjusted using a Green's Functions approach in order to optimize modeled air-sea CO2 fluxes. Data constraints include observations of carbon dioxide partial pressure (pCO2) for 2009-2010, global air-sea CO2 flux estimates, and the seasonal cycle of the Takahashi et al. (2009) Atlas. The model sensitivity experiments (or Green's Functions) include simulations that start from different initial conditions as well as experiments that perturb air-sea gas exchange parameters and the ratio of particulate inorganic to organic carbon. The Green's Functions approach yields a linear combination of these sensitivity experiments that minimizes model-data differences. The resulting initial conditions and gas exchange coefficients are then used to integrate the ECCO2-Darwin model forward. Despite the small number (six) of control parameters, the adjusted simulation is significantly closer to the data constraints (37% cost function reduction, i.e., reduction in the model-data difference, relative to the baseline simulation) and to independent observations (e.g., alkalinity). The adjusted air-sea gas

  5. The zonally averaged transport characteristics of the atmosphere as determined by a general circulation model

    NASA Technical Reports Server (NTRS)

    Plumb, R. A.

    1985-01-01

    Two dimensional modeling has become an established technique for the simulation of the global structure of trace constituents. Such models are simpler to formulate and cheaper to operate than three dimensional general circulation models, while avoiding some of the gross simplifications of one dimensional models. Nevertheless, the parameterization of eddy fluxes required in a 2-D model is not a trivial problem. This fact has apparently led some to interpret the shortcomings of existing 2-D models as indicating that the parameterization procedure is wrong in principle. There are grounds to believe that these shortcomings result primarily from incorrect implementations of the predictions of eddy transport theory and that a properly based parameterization may provide a good basis for atmospheric modeling. The existence of these GCM-derived coefficients affords an unprecedented opportunity to test the validity of the flux-gradient parameterization. To this end, a zonally averaged (2-D) model was developed, using these coefficients in the transport parameterization. Results from this model for a number of contrived tracer experiments were compared with the parent GCM. The generally good agreement substantially validates the flus-gradient parameterization, and thus the basic principle of 2-D modeling.

  6. A three-dimensional, finite element model for coastal and estuarine circulation

    USGS Publications Warehouse

    Walters, R.A.

    1992-01-01

    This paper describes the development and application of a three-dimensional model for coastal and estuarine circulation. The model uses a harmonic expansion in time and a finite element discretization in space. All nonlinear terms are retained, including quadratic bottom stress, advection and wave transport (continuity nonlinearity). The equations are solved as a global and a local problem, where the global problem is the solution of the wave equation formulation of the shallow water equations, and the local problem is the solution of the momentum equation for the vertical velocity profile. These equations are coupled to the advection-diffusion equation for salt so that density gradient forcing is included in the momentum equations. The model is applied to a study of Delaware Bay, U.S.A., where salinity intrusion is the primary focus. ?? 1991.

  7. Tropical Pacific Ocean response to observed winds in a layered general circulation model

    NASA Technical Reports Server (NTRS)

    Miller, Arthur J.; Oberhuber, Joseph M.; Graham, Nicholas E.; Barnett, Tim P.

    1992-01-01

    The effect of forcing by monthly wind-stress variability is assessed with respect to the behavior of an isopycnic coordinate general circulation model. The isopycnic model incorporates an embedded mixed layer, and the equations are given for the interior layers, the surface mixed layer, and the atmospheric forcing. The anomalous variability of several variables is examined in a simulation using data from 1970-1985 with specific attention given to the anomalous response related to the 1982-1983 ENSO. The model fields describing sea-surface temperature (SST), sea level, and currents are found to be comparable to those reported from observational campaigns. Anomalous values of SST compare best with observed data when averaged over large spatial regions, and the amplitudes of the mean horizontal currents and anomalous zonal currents are comparable except with respect to amplitude data. The present study permits the simulation of basin-scale tropical Pacific mixed-layer depth and the mean vertical velocity field.

  8. Tests of a new cloud treatment in an atmospheric general circulation model

    SciTech Connect

    Kristjansson, J.E.

    1993-12-08

    In this study we present a new cloud treatment in an atmospheric climate model. The water (or ice) content of clouds is a introduced as a prognostic variable, subject to both advective and diffusive transport. In the first phase of the study, the cloud water does not affect the radiative properties of clouds. We then find differences in precipitation and cloud fields, but little effect on the overall climate. In the second phase the cloud water determines the reflectivity of the clouds. This causes large changes in the global circulation, largely due to enhanced reflection from high tropical cirrus clouds. As a third step, the cloud emissivity is also based on the cloud water content. This greatly enhances the outgoing terrestrial radiation and brings the model`s radiative budget quite close to the observed.

  9. A search for short-term meteorological effects of solar variability in an atmospheric circulation model

    NASA Technical Reports Server (NTRS)

    Somerville, R. C. J.; Quirk, W. J.; Hansen, J. E.; Lacis, A. A.; Stone, P. H.

    1976-01-01

    A set of numerical experiments is carried out to test the short-range sensitivity of the Goddard Institute for Space Studies global atmospheric general-circulation model to changes in solar constant and ozone amount. These experiments consist of forecasts initiated with actual atmospheric data. One set of forecasts is made with a standard version of the model; another set uses the model modified by very different values of the solar constant (two-thirds and three-halves of the standard value) and of the ozone amount (zero and twice the standard amount). Twelve-day integrations with these very large variations show such small effects that the effects of realistic variations would almost certainly be insignificant meteorologically on this time scale.

  10. Dynamical predictability in a simple general circulation model - Average error growth

    NASA Technical Reports Server (NTRS)

    Schubert, Siegfried D.; Suarez, Max

    1989-01-01

    Average predictability and error growth in a simple realistic two-level general circulation model (GCM) were investigated using a series of Monte Carlo experiments for fixed external forcing (perpetual winter in the Northern Hemisphere). It was found that, for realistic initial errors, the dependence of the limit of dynamic predictability on total wavenumber was similar to that found for the ECMWF model for the 1980/1981 winter conditions, with the lowest wavenumbers showing significant skill for forecast ranges of more than 1 month. On the other hand, for very small amplitude errors distributed according to the climate spectrum, the total error growth was superexponential, reaching a maximum growth rate (2-day doubling time) in about 1 week. A simple empirical model of error variance, which involved two broad wavenumber bands and incorporating a 3/2 power saturation term, was found to provide an excellent fit to the GCM error growth behavior.

  11. Positive association of circulating levels of advanced glycation end products (AGEs) with pigment epithelium-derived factor (PEDF) in a general population.

    PubMed

    Yamagishi, Sho-Ichi; Matsui, Takanori; Adachi, Hisashi; Takeuchi, Masayoshi

    2010-02-01

    We have recently found that serum levels of pigment epithelium-derived factor (PEDF), a glycoprotein with anti-oxidative and anti-inflammatory properties, are elevated in proportion to the accumulation of the number of the components of the metabolic syndrome. Since formation and accumulation of advanced glycation end products (AGEs) progress under the metabolic syndrome and that PEDF could inhibit the AGE-elicited tissue damage, it is conceivable that PEDF levels may be increased as a counter-system against AGEs in patients with the metabolic syndrome. However, correlation between circulating levels of AGEs and PEDF in humans remains to be elucidated. In this study, we investigated the relationship between serum AGE and PEDF levels in a general population and examined the effects of AGEs on PEDF gene expression in vitro. One hundred ninety-six Japanese subjects in a general population underwent a complete history and physical examination, determination of blood chemistries, including serum levels of AGEs and PEDF. In multiple regression analyses, creatinine, body mass index, triglycerides, AGEs and insulin were independently correlated with serum PEDF levels. AGEs dose-dependently increased PEDF gene expression in cultured adipocytes and liver cells. Our present study demonstrated first that circulating AGEs were one of the independent correlates of serum levels of PEDF. Adipose tissue and liver may be target organs for the AGE-induced PEDF overexpression in humans. Serum PEDF levels may be elevated in response to circulating AGEs as a counter-system against the AGE-elicited tissue damage.

  12. Surface Lander Missions to Mars: Support via Analysis of the NASA Ames Mars General Circulation Model

    NASA Technical Reports Server (NTRS)

    Murphy, James R.; Bridger, Alison F.C.; Haberle, Robert M.

    1997-01-01

    We have characterized the near-surface martian wind environment as calculated with a set of numerical simulations carried out with the NASA Ames Mars General Circulation Model (Mars GCM). These wind environments are intended to offer future spacecraft missions to the martian surface a data base from which to choose those locations which meet the mission's criteria for minimal near surface winds to enable a successful landing. We also became involved in the development and testing of the wind sensor which is currently onboard the Mars-bound Pathfinder lander. We began this effort with a comparison of Mars GCM produced winds with those measured by the Viking landers during their descent through the martian atmosphere and their surface wind measurements during the 3+ martian year lifetime of the mission. Unexpected technical difficulties in implementing the sophisticated Planetary Boundary Layer (PBL) scheme of Haberle et al. (1993) within the Mars GCM precluded our carrying out this investigation with the desired improvement to the model's treatment of the PBL. Thus, our results from this effort are not as conclusive as we had anticipated. As it turns out, similar difficulties have been experienced by other Mars modelling groups in attempting to implement very similar PBL routines into their GCMs (Mars General Circulation Model Intercomparison Workshop, held at Oxford University, United Kingdom, July 22-24, 1996; organized by J. Murphy, J. Hollingsworth, M. Joshi). These problems, which arise due to the nature of the time stepping in each of the models, are near to being resolved at the present. The model discussions which follow herein are based upon results using the existing, less sophisticated PBL routine. We fully anticipate implementing the tools we have developed in the present effort to investigate GCM results with the new PBL scheme implemented, and thereafter producing the technical document detailing results from the analysis tools developed during this

  13. Tests of the higher order turbulence model for atmospheric circulations (HOTMAC) at Deseret Chemical Depot

    SciTech Connect

    Costigan, K.R.

    1998-11-01

    Deseret Chemical Depot is one of the US Army`s storage facilities for its stockpile of chemical weapon agents. Congress has directed the Department of Defense to eliminate the aging stockpiles, which have existed since the end of World War II, and the US Army is destroying these lethal chemical munitions. Although the danger is slight, accurate predictions of the wind field in the valley are necessary for dispersion calculations in the event of an accident involving toxic chemicals at the depot. There are several small communities in Rush and Tooele valleys, including the town of Tooele, and Salt Lake City is located 65 km to the Northeast of Deseret Chemical Depot South area, at 1,300 m MSL and beyond the Oquirrh Mountains. The purpose of this report is to carry out three-dimensional numerical simulations of the atmospheric circulations in the region around Deseret Chemical Depot with the Higher Order Turbulence Model for Atmospheric Circulations (HOTMAC) and to evaluate the performance of the model. The code had been modified to assimilate local meteorological observations through the use of Newtonian nudging. The nudging scheme takes advantage of the extensive network of local observations in the valley.

  14. Geochemical constraints on ocean general circulation models. Final report, May 1, 1995--April 30, 1997

    SciTech Connect

    Broecker, W.S.

    1998-05-17

    A better understanding of the manner in which the ocean operates is essential to the preparation for the consequences of the generation of CO{sub 2} by fossil fuel burning. Examples are as follows: (1) the ocean will ultimately take up a major fraction of the CO{sub 2} produced, but this uptake is retarded by the slow mixing rates, in order to predict the uptake, researchers must develop and validate general circulation models for the ocean; (2) during glacial time large global climate changes occurred. The changes were abrupt happening in a few decades. The trigger for these changes appears to have been reorganizations of the large-scale thermohaline circulation of the ocean. Models suggest that if the CO{sub 2} content of the atmosphere rises to more than 700 ppm, then a possibility exists that another such reorganization might occur. Hence, researchers must learn more about the factors influencing deep-water formation both in the northern Atlantic and in the Souther Ocean. The thrust of this research was to develop constraints based on the distributions of chemicals and tracers in the sea. The accomplishments are outlined in this report.

  15. Predictive models of circulating fluidized bed combustors. 12th technical progress report

    SciTech Connect

    Gidaspow, D.

    1992-07-01

    Steady flows influenced by walls cannot be described by inviscid models. Flows in circulating fluidized beds have significant wall effects. Particles in the form of clusters or layers can be seen to run down the walls. Hence modeling of circulating fluidized beds (CFB) without a viscosity is not possible. However, in interpreting Equations (8-1) and (8-2) it must be kept in mind that CFB or most other two phase flows are never in a true steady state. Then the viscosity in Equations (8-1) and (8-2) may not be the true fluid viscosity to be discussed next, but an Eddy type viscosity caused by two phase flow oscillations usually referred to as turbulence. In view of the transient nature of two-phase flow, the drag and the boundary layer thickness may not be proportional to the square root of the intrinsic viscosity but depend upon it to a much smaller extent. As another example, liquid-solid flow and settling of colloidal particles in a lamella electrosettler the settling process is only moderately affected by viscosity. Inviscid flow with settling is a good first approximation to this electric field driven process. The physical meaning of the particulate phase viscosity is described in detail in the chapter on kinetic theory. Here the conventional derivation resented in single phase fluid mechanics is generalized to multiphase flow.

  16. A Control System for the Wind Tunnel Model of a Reverse-Blowing Circulation Control Rotor (RB-CCR)

    DTIC Science & Technology

    1976-05-01

    for possible application, e.g., (1) sleeve valves , (2) cam driver poppet valves , (3) on-off (bang-bang) type valves , (4) cam nozzle valves , and (5...Identify by block number) Circulation Control Rotors Control System for High Speed Circulation Control Rotor Model Pneumatic Valving System, Dual Receiver...Continued on reverse side) 20. A STRACT (Continue on reverse side if neceesary iand IdjntIty by block number) A pneumatic valving system has been

  17. Overly persistent circulation in climate models contributes to overestimated frequency and duration of heat waves and cold spells

    NASA Astrophysics Data System (ADS)

    Plavcová, Eva; Kyselý, Jan

    2016-05-01

    The study examines links of summer heat waves and winter cold spells in Central Europe to atmospheric circulation and specifically its persistence in an ensemble of regional climate models (RCMs). We analyse 13 RCMs driven by the ERA-40 reanalysis and compare them against observations over reference period 1971-2000. Using objective classification of circulation types and an efficiency coefficient with a block resampling test, we identify circulation types significantly conducive to heat waves and cold spells. We show that the RCMs have a stronger tendency to group together days with very high or low temperature and tend to simulate too many heat waves and cold spells, especially those lasting 5 days and more. Circulation types conducive to heat waves in summer are characterized by anticyclonic, southerly and easterly flow, with increasing importance of warm advection during heat waves. Winter cold spells are typically associated with easterly and anticyclonic flow, and the onset of cold spells tends to be linked to northerly and cyclonic flow with cold advection. The RCMs are generally able to reproduce the links between circulation and heat waves or cold spells, including the radiation-to-advection effect for heat waves and the opposite advection-to-radiation effect for cold spells. They capture relatively well also changes of mean temperature anomalies during sequences of given circulation types, namely the tendency towards temperature increase (decrease) during those types conducive to heat waves (cold spells). Since mean lengths of all circulation supertypes are overestimated in the RCMs, we conclude that the overly persistent circulation in climate models contributes to the overestimated frequency of long heat waves and cold spells. As these biases are rather general among the examined RCMs and similar drawbacks are likely to be manifested in climate model simulations for the twenty-first century, the results also suggest that climate change scenarios for

  18. Venus atmosphere simulated by a high-resolution general circulation model

    NASA Astrophysics Data System (ADS)

    Sugimoto, Norihiko

    2016-07-01

    An atmospheric general circulation model (AGCM) for Venus on the basis of AFES (AGCM For the Earth Simulator) have been developed (e.g., Sugimoto et al., 2014a) and a very high-resolution simulation is performed. The highest resolution of the model is T319L120; 960 times 480 horizontal grids (grid intervals are about 40 km) with 120 vertical layers (layer intervals are about 1 km). In the model, the atmosphere is dry and forced by the solar heating with the diurnal and semi-diurnal components. The infrared radiative process is simplified by adopting Newtonian cooling approximation. The temperature is relaxed to a prescribed horizontally uniform temperature distribution, in which a layer with almost neutral static stability observed in the Venus atmosphere presents. A fast zonal wind in a solid-body rotation is given as the initial state. Starting from this idealized superrotation, the model atmosphere reaches a quasi-equilibrium state within 1 Earth year and this state is stably maintained for more than 10 Earth years. The zonal-mean zonal flow with weak midlatitude jets has almost constant velocity of 120 m/s in latitudes between 45°S and 45°N at the cloud top levels, which agrees very well with observations. In the cloud layer, baroclinic waves develop continuously at midlatitudes and generate Rossby-type waves at the cloud top (Sugimoto et al., 2014b). At the polar region, warm polar vortex zonally surrounded by a cold latitude band (cold collar) is well reproduced (Ando et al., 2016). As for horizontal kinetic energy spectra, divergent component is broadly (k>10) larger than rotational component compared with that on Earth (Kashimura et al., in preparation). Finally, recent results for thermal tides and small-scale waves will be shown in the presentation. Sugimoto, N. et al. (2014a), Baroclinic modes in the Venus atmosphere simulated by GCM, Journal of Geophysical Research: Planets, Vol. 119, p1950-1968. Sugimoto, N. et al. (2014b), Waves in a Venus general

  19. Circulation controls on southern African precipitation in coupled models: The role of the Angola Low

    NASA Astrophysics Data System (ADS)

    Munday, Callum; Washington, Richard

    2017-01-01

    In southern Africa, models from the latest Coupled Model Intercomparison Project produce a wide variety of rainfall climatologies. Differences between models in rainfall amount reach 70% in the rainy season (December-February; DJF), and the median model overestimates rainfall by between 15 and 40% throughout the annual cycle. This paper investigates the role of an understudied regional circulation feature, the Angola Low, in differentiating between model estimates of precipitation. In austral spring, the Angola Low is a heat low, driven by strong surface heating whereas in DJF it is more similar to a tropical low and is associated with moist instability. In the austral summer, we find that the simulated strength of the Angola Low is associated with between 40 and 60% of the intermodel variability in model mean rainfall across the subcontinent. The relationship is particularly strong along a northwest, southeast axis aligned from Angola down to the Mozambican Channel. Along this axis, models with stronger Angola Lows simulate enhanced, by up to 50 g kg-1 ms-1, northeasterly and northwesterly moisture transport. The enhanced southward moisture flux in models with relatively deep Angola Lows increases the rate of moisture convergence in central areas of the subcontinent and reduces moisture divergence across the Mozambican coast. The results highlight the need to better understand the links between the Angola Low and southern African rainfall and suggest that improving the simulation of the Angola Low can help to constrain model estimates of southern African rainfall.

  20. A System of Conservative Regridding for Ice-Atmosphere Coupling in a General Circulation Model (GCM)

    NASA Technical Reports Server (NTRS)

    Fischer, R.; Nowicki, S.; Kelley, M.; Schmidt, G. A.

    2014-01-01

    The method of elevation classes, in which the ice surface model is run at multiple elevations within each grid cell, has proven to be a useful way for a low-resolution atmosphere inside a general circulation model (GCM) to produce high-resolution downscaled surface mass balance fields for use in one-way studies coupling atmospheres and ice flow models. Past uses of elevation classes have failed to conserve mass and energy because the transformation used to regrid to the atmosphere was inconsistent with the transformation used to downscale to the ice model. This would cause problems for two-way coupling. A strategy that resolves this conservation issue has been designed and is presented here. The approach identifies three grids between which data must be regridded and five transformations between those grids required by a typical coupled atmosphere-ice flow model. This paper develops a theoretical framework for the problem and shows how each of these transformations may be achieved in a consistent, conservative manner. These transformations are implemented in Glint2, a library used to couple atmosphere models with ice models. Source code and documentation are available for download. Confounding real-world issues are discussed, including the use of projections for ice modeling, how to handle dynamically changing ice geometry, and modifications required for finite element ice models.

  1. Complex mean circulation over the inner shelf south of Martha's Vineyard revealed by observations and a high-resolution model

    USGS Publications Warehouse

    Ganju, Neil K.; Lentz, Steven J.; Kirincich, Anthony R.; Farrar, J. Thomas

    2011-01-01

    Inner-shelf circulation is governed by the interaction between tides, baroclinic forcing, winds, waves, and frictional losses; the mean circulation ultimately governs exchange between the coast and ocean. In some cases, oscillatory tidal currents interact with bathymetric features to generate a tidally rectified flow. Recent observational and modeling efforts in an overlapping domain centered on the Martha's Vineyard Coastal Observatory (MVCO) provided an opportunity to investigate the spatial and temporal complexity of circulation on the inner shelf. ADCP and surface radar observations revealed a mean circulation pattern that was highly variable in the alongshore and cross-shore directions. Nested modeling incrementally improved representation of the mean circulation as grid resolution increased and indicated tidal rectification as the generation mechanism of a counter-clockwise gyre near the MVCO. The loss of model skill with decreasing resolution is attributed to insufficient representation of the bathymetric gradients (Δh/h), which is important for representing nonlinear interactions between currents and bathymetry. The modeled momentum balance was characterized by large spatial variability of the pressure gradient and horizontal advection terms over short distances, suggesting that observed inner-shelf momentum balances may be confounded. Given the available observational and modeling data, this work defines the spatially variable mean circulation and its formation mechanism—tidal rectification—and illustrates the importance of model resolution for resolving circulation and constituent exchange near the coast. The results of this study have implications for future observational and modeling studies near the MVCO and other inner-shelf locations with alongshore bathymetric variability.

  2. Liquid and Ice Cloud Microphysics in the CSU General Circulation Model. Part II: Impact on Cloudiness, the Earth's Radiation Budget, and the General Circulation of the Atmosphere.

    NASA Astrophysics Data System (ADS)

    Fowler, Laura D.; Randall, David A.

    1996-03-01

    A prognostic equation for the mass of condensate associated with large-scale cloudiness introduces a direct coupling between the atmospheric moisture budget and the radiation budget through interactive cloud amounts and cloud optical properties. We have compared the cloudiness, the top-of-the-atmosphere and surface radiation budgets, the radiative forcing of clouds, and the atmospheric general circulation simulated with the Colorado State University general circulation model with and without such a prognostic cloud parameterization. In the EAULIQ run, the radiative effects of cloud water, cloud ice, and snow are considered; those of rain are omitted. The cloud optical depth and cloud infrared emissivity depend on the cloud water, cloud ice, and snow paths predicted by a bulk cloud microphysics parameterization. In the CONTROL run, a conventional large-scale condensation scheme is used. Cloud optical properties depend on the mean cloud temperatures. Results are presented in terms of January and July means.Comparisons with data from the International Satellite Cloud Climatology Project and the Earth Radiation Budget Experiment show that EAULIQ yields improved simulations of the geographical distributions of the simulated cloudiness, the top-of-the-atmosphere radiation budget, and the longwave and shortwave cloud radiative forcings. Differences between EAULIQ and CONTROL are largest in the Tropics and are mostly due to a decrease, in the EAULIQ run, in the amount and optical thickness of upper-tropospheric clouds. In particular, the cold bias in the outgoing longwave radiation and the overestimation of the planetary albedo obtained in the CONTROL run over the tropical convective regions are substantially reduced. Differences in the radiative and latent heating rates between EAULIQ and CONTROL lead to some improvements in the atmospheric general circulation simulated by EAULIQ when compared against statistics on the observed circulation assembled by the European Centre

  3. Developing Novel Therapeutic Approaches in Small Cell Lung Carcinoma Using Genetically Engineered Mouse Models and Human Circulating Tumor Cells

    DTIC Science & Technology

    2015-10-01

    Using Genetically Engineered Mouse Models and Human Circulating Tumor Cells PRINCIPAL INVESTIGATOR: Jeffrey Engelman MD PhD CONTRACTING...SUBTITLE Developiing Novel Therapeutic Approaches in Small Cell Lung 5a. CONTRACT NUMBER Carcinoma Using Genetically Engineered Mouse Models and 5b...biomarkers. 15. SUBJECT TERMS Small cell lung cancer (SCLC), Genetically engineered mouse model (GEMM), BH3 mimetic, TORC inhibitor, Apoptosis

  4. Exploring Secondary Students' Epistemological Features Depending on the Evaluation Levels of the Group Model on Blood Circulation

    ERIC Educational Resources Information Center

    Lee, Shinyoung; Kim, Heui-Baik

    2014-01-01

    The purpose of this study is to identify the epistemological features and model qualities depending on model evaluation levels and to explore the reasoning process behind high-level evaluation through small group interaction about blood circulation. Nine groups of three to four students in the eighth grade participated in the modeling practice.…

  5. Evolution of Large-Scale Circulation during TOGA COARE: Model Intercomparison and Basic Features.

    NASA Astrophysics Data System (ADS)

    Lau, K.-M.; Sheu, P. J.; Schubert, S.; Ledvina, D.; Weng, H.

    1996-05-01

    An intercomparison study of the evolution of large-scale circulation features during TOGA COARE has been carried out using data from three 4D assimilation systems: the National Meteorological Center (NMC, currently known as the National Center for Environmental Prediction), the Navy Fleet Numerical Oceanography Center, and the NASA Goddard Space Flight Center. Results show that the preliminary assimilation products, though somewhat crude, can provide important information concerning the evolution of the large-scale atmospheric circulation over the tropical western Pacific during TOGA COARE. Large-scale features such as sea level pressure, rotational wind field, and temperature are highly consistent among models. However, the rainfall and wind divergence distributions show poor agreement among models, even though some useful information can still be derived. All three models shows a continuous background rain over the Intensive Flux Area (IFA), even during periods with suppressed convection, in contrast to the radar-estimated rainfall that is more episodic. This may reflect a generic deficiency in the oversimplified representation of large-scale rain in all three models.Based on the comparative model diagnostics, a consistent picture of large-scale evolution and multiscale interaction during TOGA COARF emerges. The propagation of the Madden and Julian Oscillation (MJO) from the equatorial Indian Ocean region into the western Pacific foreshadows the establishment of westerly wind events over the COARE region. The genesis and maintenance of the westerly wind (WW) events during TOGA COARE are related to the establishment of a large-scale east-west pressure dipole between the Maritime Continent and the equatorial central Pacific. This pressure dipole could be identified in part with the ascending (low pressure) and descending (high pressure) branches of the MJO and in part with the fluctuations of the austral summer monsoon.Accompanying the development of WW over the

  6. Adaptation to mechanical load determines shape and properties of heart and circulation: the CircAdapt model.

    PubMed

    Arts, Theo; Delhaas, Tammo; Bovendeerd, Peter; Verbeek, Xander; Prinzen, Frits W

    2005-04-01

    With circulatory pathology, patient-specific simulation of hemodynamics is required to minimize invasiveness for diagnosis, treatment planning, and followup. We investigated the advantages of a smart combination of often already known hemodynamic principles. The CircAdapt model was designed to simulate beat-to-beat dynamics of the four-chamber heart with systemic and pulmonary circulation while incorporating a realistic relation between pressure-volume load and tissue mechanics and adaptation of tissues to mechanical load. Adaptation was modeled by rules, where a locally sensed signal results in a local action of the tissue. The applied rules were as follows: For blood vessel walls, 1) flow shear stress dilates the wall and 2) tensile stress thickens the wall; for myocardial tissue, 3) strain dilates the wall material, 4) larger maximum sarcomere length increases contractility, and 5) contractility increases wall mass. The circulation was composed of active and passive compliances and inertias. A realistic circulation developed by self-structuring through adaptation provided mean levels of systemic pressure and flow. Ability to simulate a wide variety of patient-specific circumstances was demonstrated by application of the same adaptation rules to the conditions of fetal circulation followed by a switch to the newborn circulation around birth. It was concluded that a few adaptation rules, directed to normalize mechanical load of the tissue, were sufficient to develop and maintain a realistic circulation automatically. Adaptation rules appear to be the key to reduce dramatically the number of input parameters for simulating circulation dynamics. The model may be used to simulate circulation pathology and to predict effects of treatment.

  7. Intercomparison and interpretation of surface energy fluxes in atmospheric general circulation models

    NASA Technical Reports Server (NTRS)

    Randall, D. A.; Cess, R. D.; Blanchet, J. P.; Boer, G. J.; Dazlich, D. A.; Del Genio, A. D.; Deque, M.; Dymnikov, V.; Galin, V.; Ghan, S. J.

    1992-01-01

    Responses of the surface energy budgets and hydrologic cycles of 19 atmospheric general circulation models to an imposed, globally uniform sea surface temperature perturbation of 4 K were analyzed. The responses of the simulated surface energy budgets are extremely diverse and are closely linked to the responses of the simulated hydrologic cycles. The response of the net surface energy flux is not controlled by cloud effects; instead, it is determined primarily by the response of the latent heat flux. The prescribed warming of the oceans leads to major increases in the atmospheric water vapor content and the rates of evaporation and precipitation. The increased water vapor amount drastically increases the downwelling IR radiation at the earth's surface, but the amount of the change varies dramatically from one model to another.

  8. Stable water isotope behavior during the last glacial maximum: A general circulation model analysis

    NASA Technical Reports Server (NTRS)

    Jouzel, Jean; Koster, Randal D.; Suozzo, Robert J.; Russell, Gary L.

    1994-01-01

    Global water isotope geochemisty during the last glacial maximum (LGM) is simulated with an 8 deg x 10 deg atmospheric general circulation model (GCM). The simulation results suggest that the spatial delta O-18/temperature relationships observed for the present day and LGM climates are very similar. Furthermore, the temporal delta O-18/temperature relationship is similar to the present-day spatial relationship in regions for which the LGM/present-day temperature change is significant. This helps justify the standard practice of applying the latter to the interpretation of paleodata, despite the possible influence of other factors, such as changes in the evaportive sources of precipitation or in the seasonality of precipitation. The model suggests, for example, that temperature shifts inferred from ice core data may differ from the true shifts by only about 30%.

  9. Effects of Southern Hemisphere Wind Changes on the Meridional Overturning Circulation in Ocean Models.

    PubMed

    Gent, Peter R

    2016-01-01

    Observations show that the Southern Hemisphere zonal wind stress maximum has increased significantly over the past 30 years. Eddy-resolving ocean models show that the resulting increase in the Southern Ocean mean flow meridional overturning circulation (MOC) is partially compensated by an increase in the eddy MOC. This effect can be reproduced in the non-eddy-resolving ocean component of a climate model, providing the eddy parameterization coefficient is variable and not a constant. If the coefficient is a constant, then the Southern Ocean mean MOC change is balanced by an unrealistically large change in the Atlantic Ocean MOC. Southern Ocean eddy compensation means that Southern Hemisphere winds cannot be the dominant mechanism driving midlatitude North Atlantic MOC variability.

  10. Simulation of the great plains low-level jet and associated clouds by general circulation models

    SciTech Connect

    Ghan, S.J.; Bian, X.; Corsetti, L.

    1996-07-01

    The low-level jet frequently observed in the Great Plains of the United States forms preferentially at night and apparently influences the timing of the thunderstorms in the region. The authors have found that both the European Centre for Medium-Range Weather Forecasts general circulation model and the National Center for Atmospheric Research Community Climate Model simulate the low-level jet rather well, although the spatial distribution of the jet frequency simulated by the two GCM`s differ considerably. Sensitivity experiments have demonstrated that the simulated low-level jet is surprisingly robust, with similar simulations at much coarser horizontal and vertical resolutions. However, both GCM`s fail to simulate the observed relationship between clouds and the low-level jet. The pronounced nocturnal maximum in thunderstorm frequency associated with the low-level jet is not simulated well by either GCM, with only weak evidence of a nocturnal maximum in the Great Plains. 36 refs., 20 figs.

  11. Characteristics modeling for supercritical circulating fluidized bed boiler working in oxy-combustion technology

    NASA Astrophysics Data System (ADS)

    Balicki, Adrian; Bartela, Łukasz

    2014-06-01

    Among the technologies which allow to reduce greenhouse gas emission, mainly carbon dioxide, special attention deserves the idea of `zeroemission' technology based on boilers working in oxy-combustion technology. In the paper the results of analyses of the influence of changing two quantities, namely oxygen share in oxidant produced in the air separation unit, and oxygen share in oxidant supplied to the furnace chamber on the selected characteristics of a steam boiler including the degree of exhaust gas recirculation, boiler efficiency and adiabatic flame temperature, was examined. Due to the possibility of the integration of boiler model with carbon dioxide capture, separation and storage installation, the subject of the analysis was also to determine composition of the flue gas at the outlet of a moisture condensation installation. Required calculations were made using a model of a supercritical circulating fluidized bed boiler working in oxy-combustion technology, which was built in a commercial software and in-house codes.

  12. Assimilating NOAA SST data into BSH operational circulation model for North and Baltic Seas

    NASA Astrophysics Data System (ADS)

    Losa, Svetlana; Schroeter, Jens; Nerger, Lars; Janjic, Tijana; Danilov, Sergey; Janssen, Frank

    A data assimilation (DA) system is developed for BSH operational circulation model in order to improve forecast of current velocities, sea surface height, temperature and salinity in the North and Baltic Seas. Assimilated data are NOAA sea surface temperature (SST) data for the following period: 01.10.07 -30.09.08. All data assimilation experiments are based on im-plementation of one of the so-called statistical DA methods -Singular Evolutive Interpolated Kalman (SEIK) filter, -with different ways of prescribing assumed model and data errors statis-tics. Results of the experiments will be shown and compared against each other. Hydrographic data from MARNET stations and sea level at series of tide gauges are used as independent information to validate the data assimilation system. Keywords: Operational Oceanography and forecasting

  13. Assimilation of drifter observations in primitive equation models of midlatitude ocean circulation

    NASA Astrophysics Data System (ADS)

    Özgökmen, Tamay M.; Molcard, Anne; Chin, Toshio M.; Piterbarg, Leonid I.; Griffa, Annalisa

    2003-07-01

    Motivated by increases in the realism of OGCMs and the number of drifting buoys in the ocean observing system, a new Lagrangian assimilation technique is implemented in an idealized, reduced-gravity configuration of the layered primitive equation model MICOM. Using an extensive set of twin experiments, the effectiveness of the Lagrangian observation operator and of a dynamical balancing technique for corrected model variables, which is based on geostrophy and mass conservation, are explored in comparison to a conventional Pseudo-Lagrangian observation operator and an implementation of the Kalman filter method. The results clearly illustrate that the Lagrangian observation operator is superior to the Pseudo-Lagrangian in the parameter range that is relevant for typical oceanic drifter observations, and that the simple dynamical balancing technique works well for midlatitude ocean circulation.

  14. Dust Emissions, Transport, and Deposition Simulated with the NASA Finite-Volume General Circulation Model

    NASA Technical Reports Server (NTRS)

    Colarco, Peter; daSilva, Arlindo; Ginoux, Paul; Chin, Mian; Lin, S.-J.

    2003-01-01

    Mineral dust aerosols have radiative impacts on Earth's atmosphere, have been implicated in local and regional air quality issues, and have been identified as vectors for transporting disease pathogens and bringing mineral nutrients to terrestrial and oceanic ecosystems. We present for the first time dust simulations using online transport and meteorological analysis in the NASA Finite-Volume General Circulation Model (FVGCM). Our dust formulation follows the formulation in the offline Georgia Institute of Technology-Goddard Global Ozone Chemistry Aerosol Radiation and Transport Model (GOCART) using a topographical source for dust emissions. We compare results of the FVGCM simulations with GOCART, as well as with in situ and remotely sensed observations. Additionally, we estimate budgets of dust emission and transport into various regions.

  15. The water cycle in the general circulation model of the martian atmosphere

    NASA Astrophysics Data System (ADS)

    Shaposhnikov, D. S.; Rodin, A. V.; Medvedev, A. S.

    2016-03-01

    Within the numerical general-circulation model of the Martian atmosphere MAOAM (Martian Atmosphere: Observation and Modeling), we have developed the water cycle block, which is an essential component of modern general circulation models of the Martian atmosphere. The MAOAM model has a spectral dynamic core and successfully predicts the temperature regime on Mars through the use of physical parameterizations typical of both terrestrial and Martian models. We have achieved stable computation for three Martian years, while maintaining a conservative advection scheme taking into account the water-ice phase transitions, water exchange between the atmosphere and surface, and corrections for the vertical velocities of ice particles due to sedimentation. The studies show a strong dependence of the amount of water that is actively involved in the water cycle on the initial data, model temperatures, and the mechanism of water exchange between the atmosphere and the surface. The general pattern and seasonal asymmetry of the water cycle depends on the size of ice particles, the albedo, and the thermal inertia of the planet's surface. One of the modeling tasks, which results from a comparison of the model data with those of the TES experiment on board Mars Global Surveyor, is the increase in the total mass of water vapor in the model in the aphelion season and decrease in the mass of water ice clouds at the poles. The surface evaporation scheme, which takes into account the turbulent rise of water vapor, on the one hand, leads to the most complete evaporation of ice from the surface in the summer season in the northern hemisphere and, on the other hand, supersaturates the atmosphere with ice due to the vigorous evaporation, which leads to worse consistency between the amount of the precipitated atmospheric ice and the experimental data. The full evaporation of ice from the surface increases the model sensitivity to the size of the polar cap; therefore, the increase in the

  16. 3D Simulations of the Early Mars Climate with a General Circulation Model

    NASA Technical Reports Server (NTRS)

    Forget, F.; Haberle, R. M.; Montmessin, F.; Cha, S.; Marcq, E.; Schaeffer, J.; Wanherdrick, Y.

    2003-01-01

    The environmental conditions that existed on Mars during the Noachian period are subject to debate in the community. In any case, there are compelling evidence that these conditions were different than what they became later in the amazonian and possibly the Hesperian periods. Indeed, most of the old cratered terrains are disected by valley networks (thought to have been carved by flowing liquid water), whereas younger surface are almost devoid of such valleys. In addition, there are evidence that the erosion rate was much higher during the early noachian than later. Flowing water is surprising on early Mars because the solar luminosity was significantly lower than today. Even with the thick atmosphere (up to several bars).To improve our understanding of the early Mars Climate, we have developed a 3D general circulation model similar to the one used on current Earth or Mars to study the details of the climate today. Our first objective is to answer the following questions : how is the Martian climate modified if 1) the surface pressure is increased up to several bars (our baseline: 2 bars) and 2) if the sun luminosity is decreased by 25 account the heat possibly released by impacts during short periods, although it may have played a role .For this purpose, we have coupled the Martian General Circulation model developed at LMD with a sophisticated correlated k distribution model developped at NASA Ames Research Center. It is a narrow band model which computes the radiative transfer at both solar and thermal wavelengths (from 0.3 to 250 microns).

  17. Local and Global Views of Systematic Errors of Atmosphere-Ocean General Circulation Models

    NASA Astrophysics Data System (ADS)

    Mechoso, C. Roberto; Wang, Chunzai; Lee, Sang-Ki; Zhang, Liping; Wu, Lixin

    2014-05-01

    Coupled Atmosphere-Ocean General Circulation Models (CGCMs) have serious systematic errors that challenge the reliability of climate predictions. One major reason for such biases is the misrepresentations of physical processes, which can be amplified by feedbacks among climate components especially in the tropics. Much effort, therefore, is dedicated to the better representation of physical processes in coordination with intense process studies. The present paper starts with a presentation of these systematic CGCM errors with an emphasis on the sea surface temperature (SST) in simulations by 22 participants in the Coupled Model Intercomparison Project phase 5 (CMIP5). Different regions are considered for discussion of model errors, including the one around the equator, the one covered by the stratocumulus decks off Peru and Namibia, and the confluence between the Angola and Benguela currents. Hypotheses on the reasons for the errors are reviewed, with particular attention on the parameterization of low-level marine clouds, model difficulties in the simulation of the ocean heat budget under the stratocumulus decks, and location of strong SST gradients. Next the presentation turns to a global perspective of the errors and their causes. It is shown that a simulated weak Atlantic Meridional Overturning Circulation (AMOC) tends to be associated with cold biases in the entire Northern Hemisphere with an atmospheric pattern that resembles the Northern Hemisphere annular mode. The AMOC weakening is also associated with a strengthening of Antarctic bottom water formation and warm SST biases in the Southern Ocean. It is also shown that cold biases in the tropical North Atlantic and West African/Indian monsoon regions during the warm season in the Northern Hemisphere have interhemispheric links with warm SST biases in the tropical southeastern Pacific and Atlantic, respectively. The results suggest that improving the simulation of regional processes may not suffice for a more

  18. Modeling and Observational Study of the Stratospheric Ozone Influences on the Tropospheric Circulation Patterns

    NASA Astrophysics Data System (ADS)

    Barodka, S.; Krasouski, A.; Shalamyansky, A.

    2013-12-01

    It seems to be universally recognized that stratospheric ozone distribution and tropospheric dynamical formations are interconnected and both affect each other in manifold processes of stratosphere-troposphere interactions. In particular, numerous observational studies suggest a clear relation between the total ozone column (TOC) field and the distribution of air-masses in both the stratosphere and the troposphere. The tropopause height being a result of two rival categories of processes (the tropospheric vertical convection and the radiative heating of the stratosphere resulting from the ozone cycle), it is natural that tropospheric and stratospheric phenomena can have an effect on each other. Indeed, it has been shown that virtually all local ozone anomalies (synoptic-scale deviations in the TOC field) correspond to local uplifts of the tropopause level, and a significant amount of research was dedicated to identification of local patterns in the stratospheric ozone distribution as the outcome of tropospheric synoptic formations and weather systems. However, in the present study we focus our attention to the opposite side of the interaction: the impact of stratospheric ozone distribution on the features of tropospheric circulation and the associated weather and regional climate conditions. For that purpose, we proceed from analyzes of the observational data performed at the A.I. Voeikov Main Geophysical Observatory, which suggest a distinct correlation between stratospheric ozone distribution, synoptic formations and air-masses boundaries in the upper troposphere and the temperature field of the lower stratosphere. Furthermore, we perform a series of numerical simulations of formation, evolution and decay of ozone anomalies of different spatial and temporal scales, introducing disturbances to the stratospheric ozone and temperature variable fields and tracing the propagation of this perturbation to tropospheric model levels. Aiming to simulate dynamical processes

  19. Global circulation of the Earth's atmosphere at altitudes from 0 to 135 Km simulated with the ARM model. Consideration of the solar activity contribution

    NASA Astrophysics Data System (ADS)

    Krivolutsky, A. A.; Cherepanova, L. A.; Dement'eva, A. V.; Repnev, A. I.; Klyuchnikova, A. V.

    2015-11-01

    The results of simulations of the global circulation and temperature regime in the altitude range from the lower tropospheric layers to 135 km are presented. They were obtained with the Atmospheric Research Model (ARM), an advanced modification of a version of the Cologne Middle Atmosphere Model (COMMA). The ARM is characterized by higher spatial resolution and better parameterizations of the radiation sources and heat sinks. At the lower boundary of the model, wavy sources of perturbations, which are caused by internal gravity waves and planetary waves, are specified. The results of the modeling of the global temperature and wind fields for the mean solar activity level are presented, and their changes, which are caused by variations of the UV-radiation fluxes in the solar activity cycle and by solar proton flares, are also considered.

  20. Advancing swine models for human health and diseases.

    PubMed

    Walters, Eric M; Prather, Randall S

    2013-01-01

    Swine models are relatively new kids on the block for modeling human health and diseases when compared to rodents and dogs. Because of the similarity to humans in size, physiology, and genetics, the pig has made significant strides in advancing the understanding of the human condition, and is thus an excellent choice for an animal model. Recent technological advances to genetic engineering of the swine genome enhance the utility of swine as models of human genetic diseases.

  1. Mathematical models of the steps involved in the systemic delivery of a chemotherapeutic to a solid tumor: From circulation to survival.

    PubMed

    Ulmschneider, Martin B; Searson, Peter C

    2015-08-28

    The efficacy of an intravenously administered chemotherapeutic for treatment of a solid tumor is dependent on a sequence of steps, including circulation, extravasation by the enhanced permeability and retention effect, transport in the tumor microenvironment, the mechanism of cellular uptake and trafficking, and the mechanism of drug action. These steps are coupled since the time dependent concentration in circulation determines the concentration and distribution in the tumor microenvironment, and hence the amount taken up by individual cells within the tumor. Models have been developed for each of the steps in the delivery process although their predictive power remains limited. Advances in our understanding of the steps in the delivery process will result in refined models with improvements in predictive power and ultimately allow the development of integrated models that link systemic administration of a drug to the probability of survival. Integrated models that predict outcomes based on patient specific data could be used to select the optimum therapeutic regimens. Here we present an overview of current models for the steps in the delivery process and highlight knowledge gaps that are key to developing integrated models.

  2. Recent developments of DMI's operational system: Coupled Ecosystem-Circulation-and SPM model.

    NASA Astrophysics Data System (ADS)

    Murawski, Jens; Tian, Tian; Dobrynin, Mikhail

    2010-05-01

    ECOOP is a pan- European project with 72 partners from 29 countries around the Baltic Sea, the North Sea, the Iberia-Biscay-Ireland region, the Mediterranean Sea and the Black Sea. The project aims at the development and the integration of the different coastal and regional observation and forecasting systems. The Danish Meteorological Institute DMI coordinates the project and is responsible for the Baltic Sea regional forecasting System. Over the project period, the Baltic Sea system was developed from a purely hydro dynamical model (version V1), running operationally since summer 2009, to a coupled model platform (version V2), including model components for the simulation of suspended particles, data assimilation and ecosystem variables. The ECOOP V2 model is currently tested and validated, and will replace the V1 version soon. The coupled biogeochemical- and circulation model runs operationally since November 2009. The daily forecasts are presented at DMI's homepage http:/ocean.dmi.dk. The presentation includes a short description of the ECOOP forecasting system, discusses the model results and shows the outcome of the model validation.

  3. Extending the NASA Ames Mars General Circulation Model to Explore Mars’ Middle Atmosphere

    NASA Astrophysics Data System (ADS)

    Brecht, Amanda; Hollingsworth, J.; Kahre, M.; Schaeffer, J.

    2013-10-01

    The NASA Ames Mars General Circulation Model (MGCM) upper boundary has been extended to ~120 km altitude (p ~10-5 mbar). The extension of the MGCM upper boundary initiates the ability to understand the connection between the lower and upper atmosphere of Mars through the middle atmosphere 70 - 120 km). Moreover, it provides the opportunity to support future missions (i.e. the 2013 MAVEN mission). A major factor in this extension is the incorporation of the Non-Local Thermodynamic Equilibrium (NLTE) heating (visible) and cooling (infrared). This modification to the radiative transfer forcing (i.e., RT code) has been significantly tested in a 1D vertical column and now has been ported to the full 3D Mars GCM. Initial results clearly show the effects of NLTE in the upper middle atmosphere. Diagnostic of seasonal mean fields and large-scale wave activity will be shown with insight into circulation patterns in the middle atmosphere. Furthermore, sensitivity tests with the resolution of the pressure and temperature grids, in which the k-coefficients are calculated upon, have been performed in the 1D RT code. Our progress on this research will be presented. Brecht is supported by NASA’s Postdoctoral Program at the Ames Research Center, administered by Oak Ridge Associated Universities through a contract with NASA.

  4. Exploring Mars' Middle Atmosphere with the Extended NASA Ames Mars General Circulation Model

    NASA Astrophysics Data System (ADS)

    Brecht, A. S.; Hollingsworth, J. L.; Kahre, M. A.; Schaeffer, J.

    2013-12-01

    The NASA Ames Mars General Circulation Model (Mars GCM) upper boundary has been extended to ~120 km altitude (pT ~ 10-6 mbar). The extension of the Mars GCM upper boundary initiates the ability to understand the connection between the lower and upper atmosphere of Mars through the middle atmosphere. Moreover, it provides the opportunity to support missions (i.e. the 2013 MAVEN mission). A major factor in this extension is the incorporation of the Non-Local Thermodynamic Equilibrium (NLTE) heating (visible) and cooling (infrared). The calculated solar heating rates (LTE heating rates) within the Mars GCM are corrected for NLTE by applying factors from Table 1 in López-Valverde et al. (1998). The CO2 15-μm cooling parameterizations is adapted from Bougher et al. (2006). This modification to the radiative transfer forcing has been significantly tested in a 1D vertical column (i.e. RT code) and now has been ported to the full 3D Mars GCM. Initial results clearly show the effects of NLTE in the upper middle atmosphere. Diagnostic of seasonal mean fields and large-scale wave activity will be shown with insight into circulation patterns in the middle atmosphere. Furthermore, sensitivity tests with the resolution of the pressure and temperature grids, in which the k-coefficients are calculated upon, have been performed in the 1D RT code. Our progress on this research will be presented.

  5. Climate Dynamics and Global Change: Temperature, Precipitation, and Circulation in GFDL Aqua-Planet Model

    NASA Astrophysics Data System (ADS)

    Dinh, T.; Fueglistaler, S.

    2015-12-01

    Numerical experiments are carried out using the GFDL General Circulation Model to assess climate sensitivity associated with CO2 increase and surface warming. This work is motivated by the calculation by Cess and Potter (1988, JGR), who proposed that surface temperature perturbations may be used as a surrogate for climate change induced by CO2 increase.We compare climatic changes due to CO2 increase in slab-ocean simulations with changes forced by surface warming in prescribed-surface-temperature simulations with fixed CO2 (Cess-type experiments). We found that slab-ocean and Cess-type experiments give the same rates of change per degree surface warming for the global atmosphere temperature and circulation strength. However, the global precipitation increases almost twice as slowly in slab-ocean runs (1.5%/K) when compared to Cess-type runs (2.8%/K). Therefore, we caution that Cess-type experiments may not be suitable for studying global precipitation change under climate change.

  6. Low-level jets in the NASA Ames Mars general circulation model

    NASA Astrophysics Data System (ADS)

    Joshi, M. M.; Haberle, R. M.; Barnes, J. R.; Murphy, J. R.; Schaeffer, J.

    1997-03-01

    Previous simulations of the Martian atmosphere have shown how topography acts to confine the low-level Hadley cell flow into intense jets on the eastern flanks of Tharsis and Syrtis Major. We now conduct detailed studies of these jets using the NASA Ames Mars general circulation model (MGCM). The structure of the flow is found to be sensitive to local topography as well as large-scale diabatic heating patterns, consistent with terrestrial studies, and MGCM studies carried out with simplified topography. The summer subtropical zonal winds associated with the Hadley circulation also form spatially confined intense jet cores. Diurnal variations in heating affect jet structure in three distinct ways. Global tides interact with the jets, resulting in effects such as the two reinforcing each other at the summer subtropics near midday, leading to high winds and surface stresses at this time. Slope winds act to change the character of the jets during the course of a day, especially at Syrtis Major and the Hellas basin, where slopes are large. Vertical mixing acts to decrease low-level winds during the late afternoon. The sensitivity of the results to atmospheric dust loading is examined. We finally show how a decrease in boundary layer height due to dust loading actually augments mid-afternoon jet strength near the surface. The resulting increase in maximum surface stress indicates that this is a positive feedback to dust lifting.

  7. Numerical Models of Human Circulatory System under Altered Gravity: Brain Circulation

    NASA Technical Reports Server (NTRS)

    Kim, Chang Sung; Kiris, Cetin; Kwak, Dochan; David, Tim

    2003-01-01

    A computational fluid dynamics (CFD) approach is presented to model the blood flow through the human circulatory system under altered gravity conditions. Models required for CFD simulation relevant to major hemodynamic issues are introduced such as non-Newtonian flow models governed by red blood cells, a model for arterial wall motion due to fluid-wall interactions, a vascular bed model for outflow boundary conditions, and a model for auto-regulation mechanism. The three-dimensional unsteady incompressible Navier-Stokes equations coupled with these models are solved iteratively using the pseudocompressibility method and dual time stepping. Moving wall boundary conditions from the first-order fluid-wall interaction model are used to study the influence of arterial wall distensibility on flow patterns and wall shear stresses during the heart pulse. A vascular bed modeling utilizing the analogy with electric circuits is coupled with an auto-regulation algorithm for multiple outflow boundaries. For the treatment of complex geometry, a chimera overset grid technique is adopted to obtain connectivity between arterial branches. For code validation, computed results are compared with experimental data for steady and unsteady non-Newtonian flows. Good agreement is obtained for both cases. In sin-type Gravity Benchmark Problems, gravity source terms are added to the Navier-Stokes equations to study the effect of gravitational variation on the human circulatory system. This computational approach is then applied to localized blood flows through a realistic carotid bifurcation and two Circle of Willis models, one using an idealized geometry and the other model using an anatomical data set. A three- dimensional anatomical Circle of Willis configuration is reconstructed from human-specific magnetic resonance images using an image segmentation method. The blood flow through these Circle of Willis models is simulated to provide means for studying gravitational effects on the brain

  8. Correlation between epidermal growth factor receptor tyrosine kinase inhibitor efficacy and circulating tumor cell levels in patients with advanced non-small cell lung cancer

    PubMed Central

    He, Wenjie; Li, Wenhui; Jiang, Bo; Chang, Li; Jin, Congguo; Tu, Changlin; Li, Yunfen

    2016-01-01

    Objective The aim of this study was to investigate the correlation between the efficacy of epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) and circulating tumor cell (CTC) levels in patients with advanced non-small cell lung cancer (NSCLC). The efficacy of EGFR-TKIs in reducing CTC counts in patients with advanced NSCLC was studied. Patients and methods A total of 66 patients with advanced NSCLC were enrolled and divided into two groups (those with high CTC counts and those with low CTC counts) based on the patients’ median CTC counts. All the patients were treated with an EGFR-TKI, and the treatment efficacy and prognoses were compared. Results The treatment efficacies were 53.3% (16/30) and 27.8% (10/36) for the low CTC group and high CTC group, respectively, and this difference was statistically significant (P<0.05). The median overall survival was 22.8 months (95% confidence interval [CI]: 18.9–26.8 months) for the low CTC group and 18.3 months (95% CI: 2.9–8.2 months) for the high CTC group. The median progression-free survival was 11.5 months (95% CI: 8.1–15 months) and 5.6 months (95% CI: 2.9–8.2 months) for the low and high CTC groups, respectively, and the difference was statistically significant (P<0.05). Conclusion The CTC count can be used as an index for predicting the EGFR-TKI effect on patients with advanced NSCLC. Efficacy and prognosis of EGFR-TKI treatment and CTC count were considered important, and the CTC count could be used to predict the efficacy of EGFR-TKI treatment and prognosis of advanced NSCLC. The change in CTC expression levels can be used as an index for evaluating the prognosis of patients with advanced NSCLC. PMID:28003764

  9. Secular Trends and Climate Drift in Coupled Ocean-Atmosphere General Circulation Models

    SciTech Connect

    Covey, C C; Gleckler, P J; Phillips, T J; Bader, D C

    2004-11-23

    Coupled ocean-atmosphere general circulation models (coupled GCMs) with interactive sea ice are the primary tool for investigating possible future global warming and numerous other issues in climate science. A long-standing problem with such models is that when different components of the physical climate system are linked together, the simulated climate can drift away from observations unless constrained by ad hoc adjustments to interface fluxes. However, eleven modern coupled GCMs--including three that do not employ flux adjustments--behave much better in this respect than the older generation of models. Surface temperature trends in control run simulations (with external climate forcing such as solar brightness and atmospheric carbon dioxide held constant) are small compared with observed trends, which include 20th century climate change due to both anthropogenic and natural factors. Sea ice changes in the models are dominated by interannual variations. Deep ocean temperature and salinity trends are small enough for model control runs to extend over 1000 simulated years or more, but trends in some regions, most notably the Arctic, are inconsistent among the models and may be problematic.

  10. The annual pressure cycle on Mars: Results from the LMD Martian atmospheric general circulation model

    NASA Technical Reports Server (NTRS)

    Hourdin, Frederic; Forget, Francois; Talagrand, O.

    1993-01-01

    We have been developing a General Circulation Model (GCM) of the martian atmosphere since 1989. The model has been described rather extensively elsewhere and only the main characteristics are given here. The dynamical part of the model, adapted from the LMD terrestrial climate model, is based on a finite-difference formulation of the classical 'primitive equations of meteorology.' The radiative transfer code includes absorption and emission by CO2 (carefully validated by comparison to line-by-line calculations) and dust in the thermal range and absorption and scattering by dust in the visible range. Other physical parameterizations are included: modeling of vertical turbulent mixing, dry convective adjustment (in order to prevent vertical unstable temperature profiles), and a multilayer model of the thermal conduction in the soil. Finally, the condensation-sublimation of CO2 is introduced through specification of a pressure-dependent condensation temperature. The atmospheric and surface temperatures are prevented from falling below this critical temperature by condensation and direct precipitation onto the surface of atmospheric CO2. The only prespecified spatial fields are the surface thermal inertia, albedo, and topography.

  11. The Tropical Subseasonal Variability Simulated in the NASA GISS General Circulation Model

    NASA Technical Reports Server (NTRS)

    Kim, Daehyun; Sobel, Adam H.; DelGenio, Anthony D.; Chen, Yonghua; Camargo, Suzana J.; Yao, Mao-Sung; Kelley, Maxwell; Nazarenko, Larissa

    2012-01-01

    The tropical subseasonal variability simulated by the Goddard Institute for Space Studies general circulation model, Model E2, is examined. Several versions of Model E2 were developed with changes to the convective parameterization in order to improve the simulation of the Madden-Julian oscillation (MJO). When the convective scheme is modified to have a greater fractional entrainment rate, Model E2 is able to simulate MJO-like disturbances with proper spatial and temporal scales. Increasing the rate of rain reevaporation has additional positive impacts on the simulated MJO. The improvement in MJO simulation comes at the cost of increased biases in the mean state, consistent in structure and amplitude with those found in other GCMs when tuned to have a stronger MJO. By reinitializing a relatively poor-MJO version with restart files from a relatively better-MJO version, a series of 30-day integrations is constructed to examine the impacts of the parameterization changes on the organization of tropical convection. The poor-MJO version with smaller entrainment rate has a tendency to allow convection to be activated over a broader area and to reduce the contrast between dry and wet regimes so that tropical convection becomes less organized. Besides the MJO, the number of tropical-cyclone-like vortices simulated by the model is also affected by changes in the convection scheme. The model simulates a smaller number of such storms globally with a larger entrainment rate, while the number increases significantly with a greater rain reevaporation rate.

  12. Oil spill model coupled to an ultra-high-resolution circulation model: implementation for the Adriatic Sea

    NASA Astrophysics Data System (ADS)

    Korotenko, K.

    2003-04-01

    An ultra-high-resolution version of DieCAST was adjusted for the Adriatic Sea and coupled with an oil spill model. Hydrodynamic module was developed on base of th low dissipative, four-order-accuracy version DieCAST with the resolution of ~2km. The oil spill model was developed on base of particle tracking technique The effect of evaporation is modeled with an original method developed on the base of the pseudo-component approach. A special dialog interface of this hybrid system allowing direct coupling to meteorlogical data collection systems or/and meteorological models. Experiments with hypothetic oil spill are analyzed for the Northern Adriatic Sea. Results (animations) of mesoscale circulation and oil slick modeling are presented at wabsite http://thayer.dartmouth.edu/~cushman/adriatic/movies/

  13. Thrust Removal Scheme for the FAST-MAC Circulation Control Model Tested in the National Transonic Facility

    NASA Technical Reports Server (NTRS)

    Chan, David T.; Milholen, William E., II; Jones, Gregory S.; Goodliff, Scott L.

    2014-01-01

    A second wind tunnel test of the FAST-MAC circulation control semi-span model was recently completed in the National Transonic Facility at the NASA Langley Research Center. The model allowed independent control of four circulation control plenums producing a high momentum jet from a blowing slot near the wing trailing edge that was directed over a 15% chord simple-hinged flap. The model was configured for transonic testing of the cruise configuration with 0deg flap deflection to determine the potential for drag reduction with the circulation control blowing. Encouraging results from analysis of wing surface pressures suggested that the circulation control blowing was effective in reducing the transonic drag on the configuration, however this could not be quantified until the thrust generated by the blowing slot was correctly removed from the force and moment balance data. This paper will present the thrust removal methodology used for the FAST-MAC circulation control model and describe the experimental measurements and techniques used to develop the methodology. A discussion on the impact to the force and moment data as a result of removing the thrust from the blowing slot will also be presented for the cruise configuration, where at some Mach and Reynolds number conditions, the thrust-removed corrected data showed that a drag reduction was realized as a consequence of the blowing.

  14. Advanced Placement: Model Policy Components. Policy Analysis

    ERIC Educational Resources Information Center

    Zinth, Jennifer

    2016-01-01

    Advanced Placement (AP), launched in 1955 by the College Board as a program to offer gifted high school students the opportunity to complete entry-level college coursework, has since expanded to encourage a broader array of students to tackle challenging content. This Education Commission of the State's Policy Analysis identifies key components of…

  15. Predicting Career Advancement with Structural Equation Modelling

    ERIC Educational Resources Information Center

    Heimler, Ronald; Rosenberg, Stuart; Morote, Elsa-Sofia

    2012-01-01

    Purpose: The purpose of this paper is to use the authors' prior findings concerning basic employability skills in order to determine which skills best predict career advancement potential. Design/methodology/approach: Utilizing survey responses of human resource managers, the employability skills showing the largest relationships to career…

  16. Dense water formation and BiOS-induced variability in the Adriatic Sea simulated using an ocean regional circulation model

    NASA Astrophysics Data System (ADS)

    Dunić, Natalija; Vilibić, Ivica; Šepić, Jadranka; Somot, Samuel; Sevault, Florence

    2016-08-01

    A performance analysis of the NEMOMED8 ocean regional circulation model was undertaken for the Adriatic Sea during the period of 1961-2012, focusing on two mechanisms, dense water formation (DWF) and the Adriatic-Ionian Bimodal Oscillating System (BiOS), which drive interannual and decadal variability in the basin. The model was verified based on sea surface temperature and sea surface height satellite measurements and long-term in situ observations from several key areas. The model qualitatively reproduces basin-scale processes: thermohaline-driven cyclonic circulation and freshwater surface outflow along the western Adriatic coast, dense water dynamics, and the inflow of Ionian and Levantine waters to the Adriatic. Positive temperature and salinity biases are reported; the latter are particularly large along the eastern part of the basin, presumably because of the inappropriate introduction of eastern Adriatic rivers into the model. The highest warm temperature biases in the vertical direction were found in dense-water-collecting depressions in the Adriatic, indicating either an inappropriate quantification of DWF processes or temperature overestimation of modelled dense water. The decadal variability in the thermohaline properties is reproduced better than interannual variability, which is considerably underestimated. The DWF rates are qualitatively well reproduced by the model, being larger when preconditioned by higher basin-wide salinities. Anticyclonic circulation in the northern Ionian Sea was modelled only during the Eastern Mediterranean Transient. No other reversals of circulation that could be linked to BiOS-driven changes were modelled.

  17. Analysis of general circulation model results and comparison with regional climatic data, Task 3. [Progress report

    SciTech Connect

    Cess, R.D.; Hameed, S.

    1989-12-31

    On time scales of greater than one year the variability of weather and climate on a large path of the Earth is dominated by the Southern Oscillation. While current theories of this phenomenon have clarified the role of the interaction between the ocean and the atmosphere in maintaining this oscillation it has so far been unclear whether the Southern Oscillation originates in the ocean, in the atmosphere or during the interaction between the ocean and the atmosphere. In this study we compared simulations of climate in two global circulation models: the coupled OSU GCM in which the atmosphere and ocean interact dynamically and the slab OSU GCM in which the ocean is represented by a static layer.

  18. Analysis of general circulation model results and comparison with regional climatic data, Task 3

    SciTech Connect

    Cess, R.D.; Hameed, S.

    1989-01-01

    On time scales of greater than one year the variability of weather and climate on a large path of the Earth is dominated by the Southern Oscillation. While current theories of this phenomenon have clarified the role of the interaction between the ocean and the atmosphere in maintaining this oscillation it has so far been unclear whether the Southern Oscillation originates in the ocean, in the atmosphere or during the interaction between the ocean and the atmosphere. In this study we compared simulations of climate in two global circulation models: the coupled OSU GCM in which the atmosphere and ocean interact dynamically and the slab OSU GCM in which the ocean is represented by a static layer.

  19. The sensitivity of latent heat flux to the air humidity approximations used in ocean circulation models

    NASA Technical Reports Server (NTRS)

    Liu, W. Timothy; Niiler, Pearn P.

    1990-01-01

    In deriving the surface latent heat flux with the bulk formula for the thermal forcing of some ocean circulation models, two approximations are commonly made to bypass the use of atmospheric humidity in the formula. The first assumes a constant relative humidity, and the second supposes that the sea-air humidity difference varies linearly with the saturation humidity at sea surface temperature. Using climatological fields derived from the Marine Deck and long time series from ocean weather stations, the errors introduced by these two assumptions are examined. It is shown that the errors reach above 100 W/sq m over western boundary currents and 50 W/sq m over the tropical ocean. The two approximations also introduce erroneous seasonal and spatial variabilities with magnitudes over 50 percent of the observed variabilities.

  20. Oceanic circulation models help to predict global biogeography of pelagic yellow-bellied sea snake.

    PubMed

    Brischoux, François; Cotté, Cédric; Lillywhite, Harvey B; Bailleul, Frédéric; Lalire, Maxime; Gaspar, Philippe

    2016-08-01

    It is well recognized that most marine vertebrates, and especially tetrapods, precisely orient and actively move in apparently homogeneous oceanic environments. Here, we investigate the presumptive role of oceanic currents in biogeographic patterns observed in a secondarily marine tetrapod, the yellow-bellied sea snake (Hydrophis [Pelamis] platurus). State-of-the-art world ocean circulation models show how H. platurus, the only pelagic species of sea snake, can potentially exploit oceanic currents to disperse and maintain population mixing between localities that spread over two-thirds of the Earth's circumference. The very close association of these snakes with surface currents seems to provide a highly efficient dispersal mechanism that allowed this species to range extensively and relatively quickly well beyond the central Indo-Pacific area, the centre of origin, abundance and diversity of sea snakes. Our results further suggest that the pan-oceanic population of this species must be extraordinarily large.

  1. The parameterization of the planetary boundary layer in the UCLA general circulation model - Formulation and results

    NASA Technical Reports Server (NTRS)

    Suarez, M. J.; Arakawa, A.; Randall, D. A.

    1983-01-01

    A planetary boundary layer (PBL) parameterization for general circulation models (GCMs) is presented. It uses a mixed-layer approach in which the PBL is assumed to be capped by discontinuities in the mean vertical profiles. Both clear and cloud-topped boundary layers are parameterized. Particular emphasis is placed on the formulation of the coupling between the PBL and both the free atmosphere and cumulus convection. For this purpose a modified sigma-coordinate is introduced in which the PBL top and the lower boundary are both coordinate surfaces. The use of a bulk PBL formulation with this coordinate is extensively discussed. Results are presented from a July simulation produced by the UCLA GCM. PBL-related variables are shown, to illustrate the various regimes the parameterization is capable of simulating.

  2. Greenhouse gas-induced climate change simulated with the CCS second-generation general circulation model

    SciTech Connect

    Boer, G.J.; Mcfarlane, N.A.; Lazare, M. )

    1992-10-01

    The Canadian Climate Centre second-generation atmospheric general circulation model coupled to a mixed-layer ocean incorporating thermodynamic sea ice is used to simulate the equilibrium climate response to a doubling of CO[sub 2]. The results of the simulation indicate a global annual warming of 3.5 C with enhanced warming found over land and at higher latitudes. Precipitation and evaporation rates increase by about 4 percent, and cloud cover decreases by 2.2 percent. Soil moisture decreases over continental Northern Hemisphere land areas in summer. The frozen component of soil moisture decreases and the liquid component increases in association with the increase of temperature at higher latitudes. The simulated accumulation rate of permanent snow cover decreases markedly over Greenland and increases slightly over Antarctica. Seasonal snow and sea ice boundaries retreat, but local decreases in planetary albedo are counteracted by tropical increases, so there is little change in the global average. 39 refs.

  3. Reconciling observed and modeled temperature and precipitation trends over Europe by adjusting for circulation variability

    NASA Astrophysics Data System (ADS)

    Saffioti, Claudio; Fischer, Erich M.; Scherrer, Simon C.; Knutti, Reto

    2016-08-01

    Europe experienced a pronounced winter cooling of about -0.37°C/decade in the period 1989-2012, in contrast to the strong warming simulated by the Coupled Model Intercomparison Project Phase 5 multimodel average during the same period. Even more pronounced discrepancies between observed and simulated short-term trends are found at the local scale, e.g., a strong winter cooling over Switzerland and a pronounced reduction in precipitation along the coast of Norway. We show that monthly sea level pressure variability accounts for much of the short-term variations of temperature over most of the domain and of precipitation in certain regions. Removing the effect of atmospheric circulation through a regression approach reconciles the observed temperature trends over Europe and Switzerland and the precipitation trend along the coast of Norway with the corresponding multimodel mean trends.

  4. Using the Variable-Resolution General Circulation Model CAM-SE to Simulate Regional Tropical Cyclone Climatology

    NASA Astrophysics Data System (ADS)

    Zarzycki, C. M.; Jablonowski, C.; Taylor, M. A.

    2012-12-01

    The ability of General Circulation Models (GCMs) to resolve tropical cyclones in the climate system has traditionally been difficult due to issues such as small storm size and the existence of key thermodynamic processes requiring significant parameterization. At traditional GCM grid resolutions of 50-300 km tropical cyclones are severely under-resolved, if not totally unresolved. Recent improvements in computational ability as well as advances in GCM model design now allow for simulations with grid spacings as small as 10-25 km. At these resolutions, models are able to more effectively capture key dynamical features of tropical cyclones. This paper explores a variable-resolution global model approach that allows for high spatial resolutions in areas of interest, such as low-latitude ocean basins where tropical cyclogenesis occurs. Such GCM designs with multi-resolution meshes serve to bridge the gap between globally uniform grids and limited area models and have the potential to become a future tool for regional climate assessments. A statically-nested, variable-resolution option has recently been introduced into the National Center for Atmospheric Research (NCAR) Community Atmosphere Model's (CAM) Spectral Element (SE) dynamical core. The SE dynamical core is also known as the 'High-Order Method Modeling Environment' (HOMME). We present aquaplanet climate experiments which showcase the ability of nested meshes to produce realistic tropical cyclones selectively in high resolution grids embedded within a global domain. We also evaluate model performance when coupled to an active land model and forced with historical sea surface temperatures by comparing multi-year results from variable-resolution CAM-SE to other globally-uniform high resolution tropical cyclone studies recently completed by the climate modeling community. Specific focus is paid to intensity profiles and track densities as well as the interannual variability in storm count in tropical regions of

  5. El Nino-southern oscillation simulated in an MRI atmosphere-ocean coupled general circulation model

    SciTech Connect

    Nagai, T.; Tokioka, T.; Endoh, M.; Kitamura, Y. )

    1992-11-01

    A coupled atmosphere-ocean general circulation model (GCM) was time integrated for 30 years to study interannual variability in the tropics. The atmospheric component is a global GCM with 5 levels in the vertical and 4[degrees]latitude X 5[degrees] longitude grids in the horizontal including standard physical processes (e.g., interactive clouds). The oceanic component is a GCM for the Pacific with 19 levels in the vertical and 1[degrees]x 2.5[degrees] grids in the horizontal including seasonal varying solar radiation as forcing. The model succeeded in reproducing interannual variations that resemble the El Nino-Southern Oscillation (ENSO) with realistic seasonal variations in the atmospheric and oceanic fields. The model ENSO cycle has a time scale of approximately 5 years and the model El Nino (warm) events are locked roughly in phase to the seasonal cycle. The cold events, however, are less evident in comparison with the El Nino events. The time scale of the model ENSO cycle is determined by propagation time of signals from the central-eastern Pacific to the western Pacific and back to the eastern Pacific. Seasonal timing is also important in the ENSO time scale: wind anomalies in the central-eastern Pacific occur in summer and the atmosphere ocean coupling in the western Pacific operates efficiently in the first half of the year.

  6. Global environmental effects of impact-generated aerosols: Results from a general circulation model, revision 1

    NASA Technical Reports Server (NTRS)

    Covey, Curt; Ghan, Steven J.; Walton, John J.; Weissman, Paul R.

    1989-01-01

    Interception of sunlight by the high altitude worldwide dust cloud generated by impact of a large asteroid or comet would lead to substantial land surface cooling, according to our three-dimensional atmospheric general circulation model (GCM). This result is qualitatively similar to conclusions drawn from an earlier study that employed a one-dimensional atmospheric model, but in the GCM simulation the heat capacity of the oceans substantially mitigates land surface cooling, an effect that one-dimensional models cannot quantify. On the other hand, the low heat capacity of the GCM's land surface allows temperatures to drop more rapidly in the initial stage of cooling than in the one-dimensional model study. These two differences between three-dimensional and one-dimensional model simulations were noted previously in studies of nuclear winter; GCM-simulated climatic changes in the Alvarez-inspired scenario of asteroid/comet winter, however, are more severe than in nuclear winter because the assumed aerosol amount is large enough to intercept all sunlight falling on earth. Impacts of smaller objects could also lead to dramatic, though less severe, climatic changes, according to our GCM. Our conclusion is that it is difficult to imagine an asteroid or comet impact leading to anything approaching complete global freezing, but quite reasonable to assume that impacts at the Alvarez level, or even smaller, dramatically alter the climate in at least a patchy sense.

  7. Application of Local Discretization Methods in the NASA Finite-Volume General Circulation Model

    NASA Technical Reports Server (NTRS)

    Yeh, Kao-San; Lin, Shian-Jiann; Rood, Richard B.

    2002-01-01

    We present the basic ideas of the dynamics system of the finite-volume General Circulation Model developed at NASA Goddard Space Flight Center for climate simulations and other applications in meteorology. The dynamics of this model is designed with emphases on conservative and monotonic transport, where the property of Lagrangian conservation is used to maintain the physical consistency of the computational fluid for long-term simulations. As the model benefits from the noise-free solutions of monotonic finite-volume transport schemes, the property of Lagrangian conservation also partly compensates the accuracy of transport for the diffusion effects due to the treatment of monotonicity. By faithfully maintaining the fundamental laws of physics during the computation, this model is able to achieve sufficient accuracy for the global consistency of climate processes. Because the computing algorithms are based on local memory, this model has the advantage of efficiency in parallel computation with distributed memory. Further research is yet desirable to reduce the diffusion effects of monotonic transport for better accuracy, and to mitigate the limitation due to fast-moving gravity waves for better efficiency.

  8. Diagnostic study of climate feedback processes in atmospheric general circulation models

    SciTech Connect

    Zhang, M.H.; Cess, R.D.; Hack, J.J.; Kiehl, J.T.

    1994-03-20

    A method is proposed to diagnose climate feedbacks of water vapor, temperature lapse-rate, and cloud variations in atmospheric general circulation models. It is then applied to study differences in sensitivity of the National Center for Atmospheric Research community climate model (CCM2) and two hybrid versions of CCM2 with different cumulus-convection schemes. Water vapor feedback and temperature lapse-rate feedback differ among the models due to different efficiencies of heat and moisture transport by cumulus convections. A large compensation occurs between water vapor feedback and temperature lapse-rate feedback. This leads to similar clear-sky sensitivities in the models. Cloud-radiative feedback is negative in CCM2 with a {delta}SST climate change due to the vigorous cumulus-convective scheme. Stronger convection warms the upper troposphere and reduces its cloudiness more, resulting in negative longwave cloud-radiative feedback. In models where a moist-adiabatic-adjustment scheme and then a decoupling of the atmospheric boundary layer are subsequently used, intensity of cumulus convection is successively reduced and cloud-radiative feedback changes to either neutral or positive. 31 refs., 21 figs., 21 tabs.

  9. A hierarchical framework for coupling surface fluxes to atompsheric general circulation models: The homogeneity test

    SciTech Connect

    Miller, N.L.

    1993-01-01

    The atmosphere and the biosphere are inherently coupled to one another. Atmospheric surface state variables such as temperature, winds, water vapor, precipitation, and radiation control biophysical, biogeochemical, and ecological processes at the surface and subsurface. At the same time, surface fluxes of momentum, moisture, heat, and trace gases act as time-dependent boundary conditions providing feedback on atmospheric processes. To understand such phenomena, a coupled set of interactive models is required. Costs are still prohibitive for computing surface/subsurface fluxes directly for medium-resolution atmospheric general circulation models (AGCMs), but a technique has been developed for testing large-scale homogeneity and accessing surface parameterizations and models to reduce this computational cost and maintain accuracy. This modeling system potentially bridges the observed spatial and temporal ranges yet allows the incorporation of necessary details about individual ecological community types or biomes and simulates the net momentum, heat, moisture, and trace gas fluxes. This suite of coupled models is defined here as the hierarchical systems flux scheme (HSFS).

  10. A hierarchical framework for coupling surface fluxes to atompsheric general circulation models: The homogeneity test

    SciTech Connect

    Miller, N.L.

    1993-12-31

    The atmosphere and the biosphere are inherently coupled to one another. Atmospheric surface state variables such as temperature, winds, water vapor, precipitation, and radiation control biophysical, biogeochemical, and ecological processes at the surface and subsurface. At the same time, surface fluxes of momentum, moisture, heat, and trace gases act as time-dependent boundary conditions providing feedback on atmospheric processes. To understand such phenomena, a coupled set of interactive models is required. Costs are still prohibitive for computing surface/subsurface fluxes directly for medium-resolution atmospheric general circulation models (AGCMs), but a technique has been developed for testing large-scale homogeneity and accessing surface parameterizations and models to reduce this computational cost and maintain accuracy. This modeling system potentially bridges the observed spatial and temporal ranges yet allows the incorporation of necessary details about individual ecological community types or biomes and simulates the net momentum, heat, moisture, and trace gas fluxes. This suite of coupled models is defined here as the hierarchical systems flux scheme (HSFS).

  11. Evaluation of rainfall simulations over West Africa in dynamically downscaled CMIP5 global circulation models

    NASA Astrophysics Data System (ADS)

    Akinsanola, A. A.; Ajayi, V. O.; Adejare, A. T.; Adeyeri, O. E.; Gbode, I. E.; Ogunjobi, K. O.; Nikulin, G.; Abolude, A. T.

    2017-03-01

    This study presents evaluation of the ability of Rossby Centre Regional Climate Model (RCA4) driven by nine global circulation models (GCMs), to skilfully reproduce the key features of rainfall climatology over West Africa for the period of 1980-2005. The seasonal climatology and annual cycle of the RCA4 simulations were assessed over three homogenous subregions of West Africa (Guinea coast, Savannah, and Sahel) and evaluated using observed precipitation data from the Global Precipitation Climatology Project (GPCP). Furthermore, the model output was evaluated using a wide range of statistical measures. The interseasonal and interannual variability of the RCA4 were further assessed over the subregions and the whole of the West Africa domain. Results indicate that the RCA4 captures the spatial and interseasonal rainfall pattern adequately but exhibits a weak performance over the Guinea coast. Findings from the interannual rainfall variability indicate that the model performance is better over the larger West Africa domain than the subregions. The largest difference across the RCA4 simulated annual rainfall was found in the Sahel. Result from the Mann-Kendall test showed no significant trend for the 1980-2005 period in annual rainfall either in GPCP observation data or in the model simulations over West Africa. In many aspects, the RCA4 simulation driven by the HadGEM2-ES perform best over the region. The use of the multimodel ensemble mean has resulted to the improved representation of rainfall characteristics over the study domain.

  12. Numerical modeling of the Arctic Ocean ice system response to variations in the atmospheric circulation from 1948 to 2007

    NASA Astrophysics Data System (ADS)

    Golubeva, E. N.; Platov, G. A.

    2009-02-01

    The results of model calculations aimed at reproducing climate changes in the Arctic Ocean due to variations in the atmospheric circulation are presented. The combined ocean-ice numerical model is based on NCAR/NCEP reanalysis data and its modified version of CIAF on the state of the lower atmosphere, radiative fluxes, and precipitation from 1948 to the present. The numerical experiments reveal the effect of the ice cover, water circulation, and thermohaline structure of the Arctic Ocean on variations in the state of the atmosphere. We found the heating and cooling periods in the Atlantic water layer, as well as the freshwater accumulation regimes in the Canadian Basin and freshwater flow through the Fram Strait and Canadian Archipelago straits. The numerical model reproduces a reconfiguration of the water circulation of the surface and intermediate layers of the ocean, a shift in the boundary between Atlantic and Pacific waters, and a significant reduction of the ice area.

  13. Modeled alongshore circulation and morphologic evolution onshore of a large submarine canyon

    NASA Astrophysics Data System (ADS)

    Hansen, J. E.; Raubenheimer, B.; List, J. H.; Elgar, S.; Guza, R. T.; Lippmann, T. C.

    2012-12-01

    Alongshore circulation and morphologic evolution observed at an ocean beach during the Nearshore Canyon Experiment, onshore of a large submarine canyon in San Diego, CA (USA), are investigated using a two-dimensional depth-averaged numerical model (Delft3D). The model is forced with waves observed in ~500 m water depth and tidal constituents derived from satellite altimetry. Consistent with field observations, the model indicates that refraction of waves over the canyon results in wave focusing ~500 m upcoast of the canyon and shadowing onshore of the canyon. The spatial variability in the modeled wave field results in a corresponding non-uniform alongshore circulation field. In particular, when waves approach from the northwest the alongshore flow converges near the wave focal zone, while waves that approach from the southwest result in alongshore flow that diverges away from the wave focal zone. The direction and magnitude of alongshore flows are determined by a balance between the (often opposing) radiation stress and alongshore pressure gradients, consistent with observations and previous results. The largest observed morphologic evolution, vertical accretion of about 1.5 m in about 3 m water depth near the wave focal zone, occurred over a one-week period when waves from the northwest reached heights of 1.8 m. The model, with limited tuning, replicates the magnitude and spatial extent of the observed accretion and indicates that net accretion of the cross-shore profile was owing to alongshore transport from converging alongshore flows. The good agreement between the observed and modeled morphology change allows for an in-depth examination of the alongshore force balance that resulted in the sediment convergence. These results indicate that, at least in this case, a depth-averaged hydrodynamic model can replicate observed surfzone morphologic change resulting from forcing that is strongly non-uniform in the alongshore. Funding was provided by the Office of Naval

  14. The Roles of Land and Orography on Precipitation and Ocean Circulation in Global Climate Models

    NASA Astrophysics Data System (ADS)

    Maroon, Elizabeth A.

    In this thesis, coupled and atmosphere-only global climate models are used to examine two large-scale climate asymmetries: the zonal asymmetry of tropical precipitation about the equator and the preference for sinking in the North Atlantic Ocean, but not in the North Pacific Ocean. The examination of these two climate asymmetries is performed using models of differing complexity. The first half of this dissertation discusses the influence of land on the distribution of tropical precipitation in idealized geometry models. A continent is added to the Northern Hemisphere subtropics of two aquaplanet models; annual mean insolation is prescribed and the albedo and longitudinal extent of the continent are varied. One of the models, GRaM, has gray-radiation physics with moist dynamics, while the other model, GFDL's AM2.1, has comprehensive physics. In the GRaM model, the pattern of the precipitation response is mostly related to decreased evaporation due to the now unsaturated surface. As the albedo of land is increased, precipitation shifts southward away from the hemisphere with less absorbed energy. In the AM2.1 model, there is a zonally-varying response in tropical precipitation due to the addition of land, but this response is not rubust in simulations that include a seasonal cycle of insolation. As albedo over land is increased, precipitation shifts southward zonally, just as in GRaM. When the width of the continent is increased, tropical precipitation shifts toward the continent, which indicates that continental width plays an important role in setting the distribution of tropical atmospheric overturning circulations. The second half of this dissertation examines the influence of Rocky Mountain orography on the location of Northern Hemisphere sinking of the oceanic meridional overturning circulation (MOC). Warren (1983) found that there is greater transport of salt into the high latitude North Atlantic than into the North Pacific, allowing water to sink in the

  15. A comparison between general circulation model simulations using two sea surface temperature datasets for January 1979

    NASA Technical Reports Server (NTRS)

    Ose, Tomoaki; Mechoso, Carlos; Halpern, David

    1994-01-01

    Simulations with the UCLA atmospheric general circulation model (AGCM) using two different global sea surface temperature (SST) datasets for January 1979 are compared. One of these datasets is based on Comprehensive Ocean-Atmosphere Data Set (COADS) (SSTs) at locations where there are ship reports, and climatology elsewhere; the other is derived from measurements by instruments onboard NOAA satellites. In the former dataset (COADS SST), data are concentrated along shipping routes in the Northern Hemisphere; in the latter dataset High Resolution Infrared Sounder (HIRS SST), data cover the global domain. Ensembles of five 30-day mean fields are obtained from integrations performed in the perpetual-January mode. The results are presented as anomalies, that is, departures of each ensemble mean from that produced in a control simulation with climatological SSTs. Large differences are found between the anomalies obtained using COADS and HIRS SSTs, even in the Northern Hemisphere where the datasets are most similar to each other. The internal variability of the circulation in the control simulation and the simulated atmospheric response to anomalous forcings appear to be linked in that the pattern of geopotential height anomalies obtained using COADS SSTs resembles the first empirical orthogonal function (EOF 1) in the control simulation. The corresponding pattern obtained using HIRS SSTs is substantially different and somewhat resembles EOF 2 in the sector from central North America to central Asia. To gain insight into the reasons for these results, three additional simulations are carried out with SST anomalies confined to regions where COADS SSTs are substantially warmer than HIRS SSTs. The regions correspond to warm pools in the northwest and northeast Pacific, and the northwest Atlantic. These warm pools tend to produce positive geopotential height anomalies in the northeastern part of the corresponding oceans. Both warm pools in the Pacific produce large

  16. Atmospheric circulation processes contributing to a multidecadal variation in reconstructed and modeled Indian monsoon precipitation

    NASA Astrophysics Data System (ADS)

    Wu, Qianru; Hu, Qi

    2015-01-01

    analysis of the recently reconstructed gridded May-September total precipitation in the Indian monsoon region for the past half millennium discloses significant variations at multidecadal timescales. Meanwhile, paleo-climate modeling outputs from the National Center for Atmospheric Research Community Climate System Model 4.0 show similar multidecadal variations in the monsoon precipitation. One of those variations at the frequency of 40-50 years per cycle is examined in this study. Major results show that this variation is a product of the processes in that the meridional gradient of the atmospheric enthalpy is strengthened by radiation loss in the high-latitude and polar region. Driven by this gradient and associated baroclinicity in the atmosphere, more heat/energy is generated in the tropical and subtropical (monsoon) region and transported poleward. This transport relaxes the meridional enthalpy gradient and, subsequently, the need for heat production in the monsoon region. The multidecadal timescale of these processes results from atmospheric circulation-radiation interactions and the inefficiency in generation of kinetic energy from the potential energy in the atmosphere to drive the eddies that transport heat poleward. This inefficiency creates a time delay between the meridional gradient of the enthalpy and the poleward transport. The monsoon precipitation variation lags that in the meridional gradient of enthalpy but leads that of the poleward heat transport. This phase relationship, and underlining chasing process by the transport of heat to the need for it driven by the meridional enthalpy gradient, sustains this multidecadal variation. This mechanism suggests that atmospheric circulation processes can contribute to multidecadal timescale variations. Interactions of these processes with other forcing, such as sea surface temperature or solar irradiance anomalies, can result in resonant or suppressed variations in the Indian monsoon precipitation.

  17. Simulation of Lake Victoria Circulation Patterns Using the Regional Ocean Modeling System (ROMS)

    PubMed Central

    Sigurdsson, Sven; Tomasson, Tumi; Taabu-Munyaho, Anthony; Sitoki, Lewis; Stefansson, Gunnar

    2016-01-01

    Lake Victoria provides important ecosystem services including transport, water for domestic and industrial uses and fisheries to about 33 million inhabitants in three East African countries. The lake plays an important role in modulating regional climate. Its thermodynamics and hydrodynamics are also influenced by prevailing climatic and weather conditions on diel, seasonal and annual scales. However, information on water temperature and circulation in the lake is limited in space and time. We use a Regional Oceanographic Model System (ROMS) to simulate these processes from 1st January 2000 to 31st December 2014. The model is based on real bathymetry, river runoff and atmospheric forcing data using the bulk flux algorithm. Simulations show that the water column exhibits annual cycles of thermo-stratification (September–May) and mixing (June–August). Surface water currents take different patterns ranging from a lake-wide northward flow to gyres that vary in size and number. An under flow exists that leads to the formation of upwelling and downwelling regions. Current velocities are highest at the center of the lake and on the western inshore waters indicating enhanced water circulation in those areas. However, there is little exchange of water between the major gulfs (especially Nyanza) and the open lake, a factor that could be responsible for the different water quality reported in those regions. Findings of the present study enhance understanding of the physical processes (temperature and currents) that have an effect on diel, seasonal, and annual variations in stratification, vertical mixing, inshore—offshore exchanges and fluxes of nutrients that ultimately influence the biotic distribution and trophic structure. For instance information on areas/timing of upwelling and vertical mixing obtained from this study will help predict locations/seasons of high primary production and ultimately fisheries productivity in Lake Victoria. PMID:27030983

  18. Modeling the effect of Causeways on Circulation in the Banana River

    NASA Astrophysics Data System (ADS)

    Saberi, A.; Weaver, R. J.

    2015-12-01

    The Indian River Lagoon (IRL) is a restricted estuary along the east coast of Florida. Although Banana River, a 50 km long sub-basin of IRL, has an outlet to the ocean through the Port Canaveral locks, the locks remain closed when there is no passing vessel. The lack of direct ocean connection results in limited circulation, long flushing time and poor water quality. Existence of the causeways limits the circulation even more. In this study, the impact of the causeways on flushing time is studied. This study also examines the extent to which constructing a low crested weir adjacent to Port Canaveral can improve flushing in this region. ADCIRC 2DDI is forced with meteorological inputs as well as tides to simulate the hydrodynamic properties of the study area and determine the 2D depth-averaged velocity field for four separate cases: Existing System with and without consideration of the causeways, and modified system (adding a weir near port Canaveral) with and without consideration of the causeways. Passive particles are placed in Banana River, and their movement is tracked using a Lagrangian Particle Tracking Model (LPTM). Transport timescales are then computed, and residence time contours as well as pathlines of selected particles are plotted. Results indicate that the narrow raised pathway section of the causeways acts as a plate which diverts the flow direction and generates eddies in the downstream which causes the particles in the vicinity of the causeways remain in the domain for a longer duration. There is a longer residence time for the case in which the causeways are considered. The results with the added weir suggest a noticeable improvement in flushing time and residence time even for the case in which the causeways are considered in the model.

  19. Wind driven general circulation of the Mediterranean Sea simulated with a Spectral Element Ocean Model

    NASA Astrophysics Data System (ADS)

    Molcard, A.; Pinardi, N.; Iskandarani, M.; Haidvogel, D. B.

    2002-05-01

    This work is an attempt to simulate the Mediterranean Sea general circulation with a Spectral Finite Element Model. This numerical technique associates the geometrical flexibility of the finite elements for the proper coastline definition with the precision offered by spectral methods. The model is reduced gravity and we study the wind-driven ocean response in order to explain the large scale sub-basin gyres and their variability. The study period goes from January 1987 to December 1993 and two forcing data sets are used. The effect of wind variability in space and time is analyzed and the relationship between wind stress curl and ocean response is stressed. Some of the main permanent structures of the general circulation (Gulf of Lions cyclonic gyre, Rhodes gyre, Gulf of Syrte anticylone) are shown to be induced by permanent wind stress curl structures. The magnitude and spatial variability of the wind is important in determining the appearance or disappearance of some gyres (Tyrrhenian anticyclonic gyre, Balearic anticyclonic gyre, Ionian cyclonic gyre). An EOF analysis of the seasonal variability indicates that the weakening and strengthening of the Levantine basin boundary currents is a major component of the seasonal cycle in the basin. The important discovery is that seasonal and interannual variability peak at the same spatial scales in the ocean response and that the interannual variability includes the change in amplitude and phase of the seasonal cycle in the sub-basin scale gyres and boundary currents. The Coriolis term in the vorticity balance seems to be responsible for the weakening of anticyclonic structures and their total disappearance when they are close to a boundary. The process of adjustment to winds produces a train of coastally trapped gravity waves which travel around the eastern and western basins, respectively in approximately 6 months. This corresponds to a phase velocity for the wave of about 1 m/s, comparable to an average velocity of

  20. A dynamic opto-physiological model to effectively interpret retinal microvascular circulation

    NASA Astrophysics Data System (ADS)

    Hassan, Harnani; Hu, Sijung; Dwyer, Vincent M.

    2015-03-01

    The demand of non-invasive ocular screening is rapidly growing due to an increase of age related eye diseases worldwide. An indeed in-depth understanding of optical properties is required to elucidate nature of retinal tissue. The research aims to investigate an effective biomedical engineering approach to allow process region of interests (ROIs) in eyes to reveal physiological status. A dynamic opto-physiological model (DOPM) representing retinal microvascular circulation underlying a diffusion approximation to solve radiative transport theorem (RTT) has being developed to interpret patho-physiological phenomena. DOPM is being applied in imaging photoplethysmography (iPPG) to extract PPG signals from a series of 2D matrix images to access blood perfusion and oxygen saturation distributions. A variation of microvascular circulation could be mapped for an effectively diagnostic screening. The work presents mathematical modelling based ten layers of ocular tissue tested with four set of controlled parameters demontrated detection ratio between normal tissue damage or abnormal tissue and significant change of AC signal amplitude in these tissues. The result shows signicant change of AC signal amplitude in abnormal tissue. The preliminary results show extractable PPG signals from eye fundus video; experimented at five ROIs: whole fundus, optical disk, main vein vessel, lesion area and affected area. The outcome shows optical disk region gave a better performance compared to whole fundus region and main vein vessel. The robustness, miniaturization and artefact reduction capability of DOPM to discriminate oxygenation levels in retina could offer a new insight to access retinal patho-physiological status.

  1. Simulation of Lake Victoria Circulation Patterns Using the Regional Ocean Modeling System (ROMS).

    PubMed

    Nyamweya, Chrispine; Desjardins, Christopher; Sigurdsson, Sven; Tomasson, Tumi; Taabu-Munyaho, Anthony; Sitoki, Lewis; Stefansson, Gunnar

    2016-01-01

    Lake Victoria provides important ecosystem services including transport, water for domestic and industrial uses and fisheries to about 33 million inhabitants in three East African countries. The lake plays an important role in modulating regional climate. Its thermodynamics and hydrodynamics are also influenced by prevailing climatic and weather conditions on diel, seasonal and annual scales. However, information on water temperature and circulation in the lake is limited in space and time. We use a Regional Oceanographic Model System (ROMS) to simulate these processes from 1st January 2000 to 31st December 2014. The model is based on real bathymetry, river runoff and atmospheric forcing data using the bulk flux algorithm. Simulations show that the water column exhibits annual cycles of thermo-stratification (September-May) and mixing (June-August). Surface water currents take different patterns ranging from a lake-wide northward flow to gyres that vary in size and number. An under flow exists that leads to the formation of upwelling and downwelling regions. Current velocities are highest at the center of the lake and on the western inshore waters indicating enhanced water circulation in those areas. However, there is little exchange of water between the major gulfs (especially Nyanza) and the open lake, a factor that could be responsible for the different water quality reported in those regions. Findings of the present study enhance understanding of the physical processes (temperature and currents) that have an effect on diel, seasonal, and annual variations in stratification, vertical mixing, inshore-offshore exchanges and fluxes of nutrients that ultimately influence the biotic distribution and trophic structure. For instance information on areas/timing of upwelling and vertical mixing obtained from this study will help predict locations/seasons of high primary production and ultimately fisheries productivity in Lake Victoria.

  2. A GENERAL CIRCULATION MODEL FOR GASEOUS EXOPLANETS WITH DOUBLE-GRAY RADIATIVE TRANSFER

    SciTech Connect

    Rauscher, Emily; Menou, Kristen

    2012-05-10

    We present a new version of our code for modeling the atmospheric circulation on gaseous exoplanets, now employing a 'double-gray' radiative transfer scheme, which self-consistently solves for fluxes and heating throughout the atmosphere, including the emerging (observable) infrared flux. We separate the radiation into infrared and optical components, each with its own absorption coefficient, and solve standard two-stream radiative transfer equations. We use a constant optical absorption coefficient, while the infrared coefficient can scale as a power law with pressure; however, for simplicity, the results shown in this paper use a constant infrared coefficient. Here we describe our new code in detail and demonstrate its utility by presenting a generic hot Jupiter model. We discuss issues related to modeling the deepest pressures of the atmosphere and describe our use of the diffusion approximation for radiative fluxes at high optical depths. In addition, we present new models using a simple form for magnetic drag on the atmosphere. We calculate emitted thermal phase curves and find that our drag-free model has the brightest region of the atmosphere offset by {approx}12 Degree-Sign from the substellar point and a minimum flux that is 17% of the maximum, while the model with the strongest magnetic drag has an offset of only {approx}2 Degree-Sign and a ratio of 13%. Finally, we calculate rates of numerical loss of kinetic energy at {approx}15% for every model except for our strong-drag model, where there is no measurable loss; we speculate that this is due to the much decreased wind speeds in that model.

  3. The sulfur cycle at high-southern latitudes in the LMD-ZT General Circulation Model

    NASA Astrophysics Data System (ADS)

    Cosme, E.; Genthon, C.; Martinerie, P.; Boucher, O.; Pham, M.

    2002-12-01

    This modeling study was motivated by the recent publication of year-round records of dimethylsulfide (DMS) and dimethylsulfoxide (DMSO) in Antarctica, completing the available series of sulfate and methanesulfonic acid (MSA). Sulfur chemistry has been incorporated in the Laboratoire de Météorologie Dynamique-Zoom Tracers (LMD-ZT) Atmospheric General Circulation Model (AGCM), with high-resolution and improved physics at high-southern latitudes. The model predicts the concentration of six major sulfur species through emissions, transport, wet and dry deposition, and chemistry in both gas and aqueous phases. Model results are broadly realistic when compared with measurements in air and snow or ice, as well as to results of other modeling studies, at high- and middle-southern latitudes. Atmospheric MSA concentrations are underestimated and DMSO concentrations are overestimated in summer, reflecting the lack of a DMSO heterogeneous sink leading to MSA. Experiments with various recently published estimates of the rate of this sink are reported. Although not corrected in this work, other defects are identified and discussed: DMS concentrations are underestimated in winter, MSA and non-sea-salt (nss) sulfate concentrations may be underestimated at the South Pole, the deposition scheme used in the model may not be adapted to polar regions, and the model does not adequately reproduces interannual variability. Oceanic DMS sources have a major contribution to the variability of sulfur in these regions. The model results suggest that in a large part of central Antarctica ground-level atmospheric DMS concentrations are larger in winter than in summer. At high-southern latitudes, high loads of DMS and DMSO are found and the main chemical sink of sulfur dioxide (SO2) is aqueous oxidation by ozone (O3), whereas oxidation by hydrogen peroxide (H2O2) dominates at the global scale. A comprehensive modeled sulfur budget of Antarctica is provided.

  4. Overly persistent circulation in climate models contributes to overestimated frequency and duration of heat waves and cold spells

    NASA Astrophysics Data System (ADS)

    Plavcova, Eva; Kysely, Jan

    2016-04-01

    The study examines links of summer heat waves and winter cold spells in Central Europe to atmospheric circulation and specifically its persistence in an ensemble of regional climate models (RCMs). We analyse 13 RCMs driven by the ERA-40 reanalysis and compare them against observations over 1971-2000. Using objective classification of circulation types and an efficiency coefficient with a block resampling test, we identify circulation types significantly conducive to heat waves and cold spells. We show that the RCMs have a stronger tendency to group together days with very high or low temperature and tend to simulate too many heat waves and cold spells, especially those lasting 5 days and more. Circulation types conducive to heat waves in summer are characterized by anticyclonic, southerly and easterly flow, with increasing importance of warm advection during heat waves. Winter cold spells are typically associated with easterly and anticyclonic flow, and the onset of cold spells tends to be linked to northerly and cyclonic flow with cold advection. The RCMs are generally able to reproduce the links between circulation and heat waves or cold spells, including the radiation-to-advection effect for heat waves and the opposite advection-to-radiation effect for cold spells. They capture relatively well also changes of mean temperature anomalies during sequences of given circulation types, namely the tendency towards an increase (decrease) of temperature during the types conducive to heat waves (cold spells). Since mean lengths of all circulation supertypes are overestimated in the RCMs, we conclude that the overly persistent circulation in climate models contributes to the overestimated frequency of long heat waves and cold spells. As these biases are rather general among the examined RCMs and similar drawbacks are likely to be manifested in climate model simulations for the 21st century, the results also suggest that climate change scenarios for spells of days with high

  5. Global warming and the weakening of the Asian summer monsoon circulation: assessments from the CMIP5 models

    NASA Astrophysics Data System (ADS)

    Sooraj, K. P.; Terray, Pascal; Mujumdar, M.

    2015-07-01

    The evolution of the Asian summer monsoon (ASM) in a global warming environment is a serious scientific and socio-economic concern since many recent studies have demonstrated the weakening nature of large-scale tropical circulation under anthropogenic forcing. But, how such processes affect the ASM circulation and rainfall is still a matter of debate. This study examines the climate model projections from a selected set of Coupled Model Inter-comparison Project 5 (CMIP5) models to provide a unified perspective on the future ASM response. The results indicate a robust reduction in the large-scale meridional gradient of temperature (MGT) at upper levels (200 hPa) over the ASM region, associated with enhanced ascendance and deep tropospheric heating over the equatorial Pacific in the future climate. The differential heating in the upper troposphere, with concomitant increase (decrease) in atmospheric stability (MGT), weakens the ASM circulation, promotes a northward shift of the monsoon circulation and a widening of the local Hadley cell in the eastern Indian sector. An examination of the water vapour budget indicates the competing effects of the thermodynamic (moisture convergence) and dynamics processes (monsoon circulation) on future ASM rainfall changes. The former component wins out over the later one and leads to the intensification of Indian monsoon rainfall in the CMIP5 projections. However, the diagnostics further show a considerable offset due to the dynamic component.

  6. Alumina calcination with the advanced circulating fluid bed technology: A design with increased efficiency combined with operating flexibility

    SciTech Connect

    Schmidt, H.W.; Stockhausen, W.; Silberberg, A.N.

    1996-10-01

    The Circulating Fluid Bed (CFB) technology has now been applied to alumina calcination for a quarter of a century. The combined capacity of the 32 units installed is greater than 10 million metric tons per year. The paper highlights the consistency of the product quality which is based upon the operating experience of the last decade and improvements to the calcination system which also provides lower heat consumption. The principal modifications are incorporated in the preheating and cooling sections of the plant. These design modifications have also reduced capital cost. Overall the plant retains its proven features of high flexibility, unique temperature control, high availability, reliable performance, and low maintenance cost. The design is applicable to single train units up to a capacity of 3,000 MTPD (alumina).

  7. Wall jet analysis for circulation control aerodynamics. Part 2: Zonal modeling concepts for wall jet/potential flow coupling

    NASA Technical Reports Server (NTRS)

    Dvorak, Frank A.; Dash, Sanford M.

    1987-01-01

    Work currently in progress to update an existing transonic circulation control airfoil analysis method is described. Existing methods suffer from two dificiencies: the inability to predict the shock structure of the underexpanded supersonic jets; and the insensitivity of the calculation to small changes in the Coanda surface geometry. A method developed for the analysis of jet exhaust plumes in supersonic flow is being modified for the case of the underexpanded wall jet. In the subsonic case, the same wall jet model was modified to include the calculation of the normal pressure gradient. This model is currently being coupled with the transonic circulation control airfoil analysis.

  8. Three-dimensional computer model for the atmospheric general circulation experiment

    NASA Technical Reports Server (NTRS)

    Roberts, G. O.

    1984-01-01

    An efficient, flexible, three-dimensional, hydrodynamic, computer code has been developed for a spherical cap geometry. The code will be used to simulate NASA's Atmospheric General Circulation Experiment (AGCE). The AGCE is a spherical, baroclinic experiment which will model the large-scale dynamics of our atmosphere; it has been proposed to NASA for future Spacelab flights. In the AGCE a radial dielectric body force will simulate gravity, with hot fluid tending to move outwards. In order that this force be dominant, the AGCE must be operated in a low gravity environment such as Spacelab. The full potential of the AGCE will only be realized by working in conjunction with an accurate computer model. Proposed experimental parameter settings will be checked first using model runs. Then actual experimental results will be compared with the model predictions. This interaction between experiment and theory will be very valuable in determining the nature of the AGCE flows and hence their relationship to analytical theories and actual atmospheric dynamics.

  9. Variation of the global electric circuit and Ionospheric potential in a general circulation model

    NASA Astrophysics Data System (ADS)

    Mareev, E. A.; Volodin, E. M.

    2014-12-01

    A general circulation model of the atmosphere and ocean INMCM4.0 (Institute of Numerical Mathematics Coupled Model) is used for modeling the global electric circuit short-time variability and long-term evolution. The ionospheric potential parameterization is proposed which takes into account quasi-stationary currents of electrified clouds (including thunderstorms) as principal contributors into the DC global circuit. The diurnal, seasonal, and interannual variations of the ionospheric potential (IP) are modeled and compared with available data. Numerical simulations suggest that the IP decreases in the mean with the global warming due to increasing greenhouse gas emission (by about 10% during the 21st century if the Representative Concentration Pathway 8.5 Wm-2 scenario is assumed). At the same time the lightning flash rate increases with global warming by about 5 fl/s per degree. Interannual IP variability is low and does not exceed 1% of the mean value, being tightly correlated with the mean sea surface temperature in the Pacific Ocean (El Niño area).

  10. Hurricane Forecasting with the High-resolution NASA Finite-volume General Circulation Model

    NASA Technical Reports Server (NTRS)

    Atlas, R.; Reale, O.; Shen, B.-W.; Lin, S.-J.; Chern, J.-D.; Putman, W.; Lee, T.; Yeh, K.-S.; Bosilovich, M.; Radakovich, J.

    2004-01-01

    A high-resolution finite-volume General Circulation Model (fvGCM), resulting from a development effort of more than ten years, is now being run operationally at the NASA Goddard Space Flight Center and Ames Research Center. The model is based on a finite-volume dynamical core with terrain-following Lagrangian control-volume discretization and performs efficiently on massive parallel architectures. The computational efficiency allows simulations at a resolution of a quarter of a degree, which is double the resolution currently adopted by most global models in operational weather centers. Such fine global resolution brings us closer to overcoming a fundamental barrier in global atmospheric modeling for both weather and climate, because tropical cyclones and even tropical convective clusters can be more realistically represented. In this work, preliminary results of the fvGCM are shown. Fifteen simulations of four Atlantic tropical cyclones in 2002 and 2004 are chosen because of strong and varied difficulties presented to numerical weather forecasting. It is shown that the fvGCM, run at the resolution of a quarter of a degree, can produce very good forecasts of these tropical systems, adequately resolving problems like erratic track, abrupt recurvature, intense extratropical transition, multiple landfall and reintensification, and interaction among vortices.

  11. Global environmental effects of impact-generated aerosols: Results from a general circulation model

    NASA Technical Reports Server (NTRS)

    Covey, Curt; Ghan, Steven J.; Walton, John J.; Weissman, Paul R.

    1989-01-01

    Interception of sunlight by the high altitude worldwide dust cloud generated by impact of a large asteroid or comet would lead to substantial land surface cooling, according to the three-dimensional atmospheric general circulation model (GCM). This result is qualitatively similar to conclusions drawn from an earlier study that employed a one-dimensional atmospheric model, but in the GCM simulation the heat capacity of the oceans, not included in the one-dimensional model, substantially mitigates land surface cooling. On the other hand, the low heat capacity of the GCM's land surface allows temperatures to drop more rapidly in the initial stages of cooling than in the one-dimensional model study. GCM-simulated climatic changes in the scenario of asteroid/comet winter are more severe than in nuclear winter because the assumed aerosol amount is large enough to intercept all sunlight falling on earth. Impacts of smaller objects could also lead to dramatic, though of course less severe, climatic changes, according to the GCM. An asteroid or comet impact would not lead to anything approaching complete global freezing, but quite reasonable to assume that impacts would dramatically alter the climate in at least a patchy sense.

  12. Thermosphere-Ionosphere-Electrodynamics General Circulation Model for the Ionospheric Connection Explorer: TIEGCM-ICON

    NASA Astrophysics Data System (ADS)

    Maute, Astrid

    2017-04-01

    The NASA Ionospheric Connection explorer (ICON) will study the coupling between the thermosphere and ionosphere at low- and mid-latitudes by measuring the key parameters. The ICON mission will also employ numerical modeling to support the interpretation of the observations, and examine the importance of different vertical coupling mechanisms by conducting numerical experiments. One of these models is the Thermosphere-Ionosphere-Electrodynamics General Circulation Model-ICON (TIEGCM-ICON) which will be driven by tidal perturbations derived from ICON observations using the Hough Mode Extension method (HME) and at high latitude by ion convection and auroral particle precipitation patterns from the Assimilative Mapping of Ionospheric Electrodynamics (AMIE). The TIEGCM-ICON will simulate the thermosphere-ionosphere (TI) system during the period of the ICON mission. In this report the TIEGCM-ICON is introduced, and the focus is on examining the effect of the lower boundary on the TI-system to provide some guidance for interpreting future ICON model results.

  13. The GEOS-5 Atmospheric General Circulation Model: Mean Climate and Development from MERRA to Fortuna

    NASA Technical Reports Server (NTRS)

    Molod, Andrea; Takacs, Lawrence; Suarez, Max; Bacmeister, Julio; Song, In-Sun; Eichmann, Andrew

    2012-01-01

    This report is a documentation of the Fortuna version of the GEOS-5 Atmospheric General Circulation Model (AGCM). The GEOS-5 AGCM is currently in use in the NASA Goddard Modeling and Assimilation Office (GMAO) for simulations at a wide range of resolutions, in atmosphere only, coupled ocean-atmosphere, and data assimilation modes. The focus here is on the development subsequent to the version that was used as part of NASA s Modern-Era Retrospective Analysis for Research and Applications (MERRA). We present here the results of a series of 30-year atmosphere-only simulations at different resolutions, with focus on the behavior of the 1-degree resolution simulation. The details of the changes in parameterizations subsequent to the MERRA model version are outlined, and results of a series of 30-year, atmosphere-only climate simulations at 2-degree resolution are shown to demonstrate changes in simulated climate associated with specific changes in parameterizations. The GEOS-5 AGCM presented here is the model used for the GMAO s atmosphere-only and coupled CMIP-5 simulations.

  14. A circulation modeling approach for evaluating the conditions for shoreline instabilities

    USGS Publications Warehouse

    List, Jeffrey H.; Ashton, Andrew D.

    2007-01-01

    Analytical models predict the growth (instability) of shoreline salients when deep-water waves approach the coast from highly oblique angles, contrary to classical shoreline change models in which shoreline salients can only dissipate. Using the process-based wave, circulation, and sediment transport model Delft3D, we test this prediction for simulated bathymetric and wave characteristics approximating the open-ocean conditions at Duck, North Carolina. We consider two cases: a uniform coast with a varying wave approach angle, and a bathymetry with coastal salients and a single high-angle boundary wave condition. Incident wave conditions include a swell case with no wind and a wind-wave case with active local wave regeneration by wind. The uniform-coast tests predict transport maxima at oblique wave angles for both wave cases, indicating the potential for shoreline instabilities, similar to the analytical models. However, the critical angle for instability is much higher in the wind-wave case. Our tests with coastal salients agree with previous findings that a minimum salient length scale may be required for the instability effect to be active. Here, a salient with a longshore scale of 4 km results in transport divergence (erosion; no instability) at the salient crest while an 8 km salient results in transport convergence (accretion; instability) at the crest.

  15. An Infrared Radiative Transfer Parameterization For A Venus General Circulation Model

    NASA Astrophysics Data System (ADS)

    Eymet, Vincent; Fournier, R.; Lebonnois, S.; Bullock, M. A.; Dufresne, J.; Hourdin, F.

    2006-09-01

    A new 3-dimensional General Circulation Model (GCM) of Venus'atmosphere is curently under development at the Laboratoire de Meteorologie Dynamique, in the context of the Venus-Express mission. Special attention was devoted to the parameterization of infrared radiative transfer: this parameterization has to be both very fast and sufficiently accurate in order to provide valid results over extented periods of time. We have developped at the Laboratoire d'Energetique a Monte-Carlo code for computing reference radiative transfer results for optically thick inhomogeneous scattering planetary atmospheres over the IR spectrum. This code (named KARINE) is based on a Net-Exchange Rates formulation, and uses a k-distribution spectral model. The Venus spectral data, that was compiled at the Southwest Research Institute, accounts for gaseous absorption and scattering, typical clouds absorption and scattering, as well as CO2 and H2O absorption continuums. We will present the Net-Exchange Rates matrix that was computed using the Monte-Carlo approach. We will also show how this matrix has been used in order to produce a first-order radiative transfer parameterization that is used in the LMD Venus GCM. In addition, we will present how the proposed radiative transfer model was used in a simple convective-radiative equilibrium model in order to reproduce the main features of Venus' temperature profile.

  16. The extratropical 40-day oscillation in the UCLA general circulation model. Part 1: Atmospheric angular momentum

    NASA Technical Reports Server (NTRS)

    Marcus, S. L.; Ghil, M.; Dickey, J. O.

    1994-01-01

    Variations in atmospheric angular momentum (AAM) are examined in a three-year simulation of the large-scale atmosphere with perpetual January forcing. The simulation is performed with a version of the University of California at Los Angeles (UCLA) general circulation model that contains no tropical Madden-Julian Oscillation (MJO). In addition, the results of three shorter experiments with no topography are analyzed. The three-year standard topography run contains no significant intraseasonal AAM periodicity in the tropics, consistent with the lack of the MJO, but produces a robust, 42-day AAM oscillation in the Northern Hemisphere (NH) extratropics. The model tropics undergoes a barotropic, zonally symmetric oscillation, driven by an exchange of mass with the NH extratropics. No intraseasonal periodicity is found in the average tropical latent heating field, indicating that the model oscillation is dynamically rather than thermodynamically driven. The no-mountain runs fail to produce an intraseasonal AAM oscillation, consistent with a topographic origin for the NH extratropical oscillation in the standard model. The spatial patterns of the oscillation in the 500-mb height field, and the relationship of the extratropical oscillation to intraseasonal variations in the tropics, will be discussed in Part 2 of this study.

  17. Assessment of the non-hydrostatic effect in general circulation models (GCMs)

    NASA Astrophysics Data System (ADS)

    Deng, Y.; Richmond, A. D.; Ridley, A. J.; Liu, H.

    2007-12-01

    Under hydrostatic equilibrium, a typical assumption used in global thermosphere ionosphere models, the pressure gradient in the vertical direction is exactly balanced by the gravity force. Using the Global Ionosphere Thermosphere Model (GITM), which solves the complete vertical momentum equation, the primary characteristics of non-hydrostatic effects on the upper atmosphere are investigated. Our results show that after a sudden intense enhancement of high-latitude Joule heating, the vertical pressure gradient force can locally be 25 percent larger than the gravity force, resulting in a significant disturbance away from hydrostatic equilibrium. This disturbance is transported from the lower altitude source region to high altitudes through an acoustic wave, which has been simulated in a global circulation model for the first time. Due to the conservation of perturbation energy, the magnitude of the vertical wind perturbation increases with altitude and reaches 150 (250) m/s at 300 (430) km during the disturbance. The upward neutral wind lifts the atmosphere and raises the neutral density at high altitudes by a factor of two. While the time scale of the buoyancy acceleration perturbation is around 5-10 minutes in this case, the large vertical wind (above 50 m/s) at 300 km altitude lasts for a significantly longer time, and depends on the lifetime of the forcing. These large vertical winds are observed and are not typically reproduced by hydrostatic models of the thermosphere and ionosphere.

  18. Clouds-radiation interactions in a general circulation model: Impact upon the planetary radiation balance

    SciTech Connect

    Smith, L.D.; Vonder Haar, T.H. )

    1991-01-20

    The unique multimonth set of simultaneous Earth radiation budget observations and cloud amount estimates taken during the Nimbus 7 satellite mission from June 1979 to May 1980 was used to validate a long-term climate simulation obtained with the latest version of the National Center for Atmospheric Research (NCAR) Community Climate Model. The comparison focused on the temporal variability of the model-generated cloud and radiation fields versus satellite data with the aim to (1) test the model's ability to simulate short-term fluctuations; and (2) examine the impact of the treatment of the interactions between clouds, radiation, and the hydrologic cycle on the model's performance. The Nimbus 7 data set comprised broad-spectral-band observations of the outgoing infrared radiation and planetary albedo taken by the Earth radiation budget scanners and total cloud amount estimates derived from radiances measured by the Temperature Humidity Infrared Radiometer and Total Ozone Mapping Spectrometer. Model-simulated northern hemisphere summer and winter seasons were obtained from a 15-year time integration including a seasonal cycle. Although the global distributions of the seasonal average and standard deviation of the model-generated cloud and radiation fields agreed reasonably well with those obtained from satellite observations, the magnitude of the standard deviation of both fields was overestimated by about a factor of 2 over the whole globe. In view of the impact of clouds on the atmospheric circulation and its temporal variability, increased fluctuations in cloudiness may affect the sensitivity of the model-simulated climate to external forcings and it is desirable to implement stronger couplings between the various physical processes in the NCAR Community Climate Model.

  19. Distribution and budget of O3 in the troposphere calculated with a chemistry general circulation model

    NASA Astrophysics Data System (ADS)

    Roelofs, Geert-Jan; Lelieveld, Jos

    1995-10-01

    We present results of global tropospheric chemistry simulations with the coupled chemistry/atmospheric general circulation model ECHAM. Ultimately, the model will be used to study climate changes induced by anthropogenic influences on the chemistry of the atmosphere; meteorological parameters that are important for the chemistry, such as temperature, humidity, air motions, cloud and rain characteristics, and mixing processes are calculated on-line. The chemical part of the model describes background tropospheric CH4-CO-NOx-HOx photochemistry. Emissions of NO and CO, surface concentrations of CH4, and stratospheric concentrations of O3 and NOy are prescribed as boundary conditions. Calculations of the tropospheric O3 budget indicate that seasonal variabilities of the photochemical production and of injection from the stratosphere are represented realistically, although some aspects of the model still need improvement. Comparisons of calculated O3 surface concentrations and O3 profiles with available measurements show that the model reproduces O3 distributions in remote tropical and midlatitudinal sites. Also, the model matches typical profiles connected with deep convection in the Intertropical Convergence Zone (ITCZ). However, the model tends to underestimate O3 concentrations at the poles and in relatively polluted regions. These underestimates are caused by the poor representation of tropopause foldings in midlatitudes, which form a significant source of tropospheric O3 from the stratosphere, too weak transport to the poles, and the neglect of higher hydrocarbon chemistry. Also, mixing of polluted continental boundary layer air into the free troposphere may be underestimated. We discuss how these model deficiencies will be improved in the future.

  20. Evaluation of the Surface Representation of the Greenland Ice Sheet in a General Circulation Model

    NASA Technical Reports Server (NTRS)

    Cullather, Richard I.; Nowicki, Sophie M. J.; Zhao, Bin; Suarez, Max J.

    2014-01-01

    Simulated surface conditions of the Goddard Earth Observing System model, version 5 (GEOS 5) atmospheric general circulation model (AGCM) are examined for the contemporary Greenland Ice Sheet (GrIS). A surface parameterization that explicitly models surface processes including snow compaction, meltwater percolation and refreezing, and surface albedo is found to remedy an erroneous deficit in the annual net surface energy flux and provide an adequate representation of surface mass balance (SMB) in an evaluation using simulations at two spatial resolutions. The simulated 1980-2008 GrIS SMB average is 24.7+/-4.5 cm yr(- 1) water-equivalent (w.e.) at.5 degree model grid spacing, and 18.2+/-3.3 cm yr(- 1) w.e. for 2 degree grid spacing. The spatial variability and seasonal cycle of the simulation compare favorably to recent studies using regional climate models, while results from 2 degree integrations reproduce the primary features of the SMB field. In comparison to historical glaciological observations, the coarser resolution model overestimates accumulation in the southern areas of the GrIS, while the overall SMB is underestimated. These changes relate to the sensitivity of accumulation and melt to the resolution of topography. The GEOS-5 SMB fields contrast with available corresponding atmospheric models simulations from the Coupled Model Intercomparison Project (CMIP5). It is found that only a few of the CMIP5 AGCMs examined provide significant summertime runoff, a dominant feature of the GrIS seasonal cycle. This is a condition that will need to be remedied if potential contributions to future eustatic change from polar ice sheets are to be examined with GCMs.