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1

Radiative flux measurements in the troposphere  

Microsoft Academic Search

The results of radiative flux-density measurements in the troposphere, made using an especially designed radiometer mounted on a Cessna 402B aircraft, are reported. The radiometer incorporates several well-known principles that result in highly accurate determinations of radiative fluxes in the atmosphere. Heating rates for gases and for aerosols are calculated, using measurements and radiosonde data. Instrument performance is verified by

Francisco P. J. Valero; Warren J. Y. Gore; Lawrence P. M. Giver

1982-01-01

2

Radiative flux measurements in the troposphere  

SciTech Connect

The results of radiative flux-density measurements in the troposphere, made using an especially designed radiometer mounted on a Cessna 402B aircraft, are reported. The radiometer incorporates several well-known principles that result in highly accurate determinations of radiative fluxes in the atmosphere. Heating rates for gases and for aerosols are calculated, using measurements and radiosonde data. Instrument performance is verified by calculating the solar constant at the top of the atmosphere, using the radiative flux densities measured in the troposphere. Total heating rates of 0.175 and 0.377 K h/sup -1/ are determined for hazy and foggy atmospheres, respectively. Aerosol heating rates of 0.065 and 0.235 K h/sup -1/ are deduced from the total heating rates. Environmental noise measurements during data acquisition are presented. The solar constant value of 1387 +- 21 W m/sup -2/ derived from the experiments agrees within 4% of the standard value.

Valero, F.P.J.; Gore, W.J.Y.; Giver, L.P.M.

1982-03-01

3

Measurement of Outgoing Radiative Fluxes from Ultra Long Duration Balloons  

NASA Astrophysics Data System (ADS)

Top of Atmosphere TOA radiative fluxes W m 2 are critical to our understanding of the physics of the present climate and it is variability Recognizing this importance NASA has measured the shortwave 0 2--4 mu m fluxes reflected by the Earth-atmosphere system and longwave 4--100 mu m fluxes emitted by the Earth-atmosphere systme for almost 40 years Outgoing flux can be measured directly from satellite using wide field of view radiometers with a footprint of a few thousand kilometers In order to provide fluxes more commensurate with the increasingly fine resolution of climate models Earth radiation budget satellite the Cloud and Earth s Radiant Energy System CERES on Terra and Aqua is based entirely on narrow filed of view scanner to measure directional radiances W m 2 sr Therefore we have to rely on empirical angular directional models to convert radiance to flux which is the principle source of uncertainty in instantaneous fluxes estimated from Earth radiation budget satellites Unlike other retrieved variables emph in situ validation of outgoing fluxes has been nearly impossible for lack of platforms that operate for long periods at the top of atmosphere The NASA Ultra Long Duration Balloon ULDB program opens a new avenue for direct measurement of the Earth radiation budget Radiative transfer model shows that the outgoing flux differences between ULDB flight altitude and TOA is less than 1 W m 2 Therefore it provides a unique platform to validate the satellite retrieved TOA radiative fluxes An Earth radiation balloon package has

Su, W.; Dutton, E.; Charlock, T.; Wiscombe, W.

4

Design of a differential radiometer for atmospheric radiative flux measurements  

SciTech Connect

The Hemispherical Optimized NEt Radiometer (HONER) is an instrument under development at the Los Alamos National Laboratory for deployment on an unmanned aerospace vehicle as part of the Atmospheric Radiation Measurements (ARM/UAV) program. HONER is a differential radiometer which will measure the difference between the total upwelling and downwelling fluxes and is intended to provide a means of measuring the atmospheric radiative flux divergence. Unlike existing instruments which measure the upwelling and downwelling fluxes separately, HONER will achieve an optical difference by chopping the two fluxes alternately onto a common pyroelectric detector. HONER will provide data resolved into two spectral bands; one covering the solar dominated region from less than 0.4 micrometer to approximately 4.5 micrometers and the other covering the region from approximately 4.5 micrometers to greater than 50 micrometers, dominated by thermal radiation. The means of separating the spectral regions guarantees seamless summation to calculate the total flux. The fields-of-view are near-hemispherical, upward and downward. The instrument can be converted, in flight, from the differential mode to absolute mode, measuring the upwelling and downwelling fluxes separately and simultaneously. The instrument also features continuous calibration from on-board sources. We will describe the design and operation of the sensor head and the on-board reference sources as well as the means of deployment.

LaDelfe, P.C.; Weber, P.G.; Rodriguez, C.W.

1994-11-01

5

Direct Retrieval of Radiative Flux-Divergence and Radiative Forcing from Satellite Spectral Measurements.  

NASA Astrophysics Data System (ADS)

We explore the concept of a retrieval of the thermal infrared radiative flux divergence and cooling rate profile using top-of-atmosphere spectral radiance measurements and demonstrate that the retrieval of this quantity can be performed directly. We show that the inversion encountered in this problem is sensitive to the initial atmospheric state vector assumed a priori. However, the direct approach has specific advantageous in terms of accuracy and computational speed, as compared to the conventional indirect approach using the retrieved atmospheric state vector coupled with a line-by-line radiative transfer model in cooling rate calculations. Furthermore, we show that the spectrally-resolved radiative forcing at the tropopause can be derived directly from the retrieved flux-divergence profile. As a test case, we carried out retrieval in the strong cooling band associated with the 15 ?m band of CO2 employing the Atmospheric Infrared Sounder (AIRS, 2002-present) on board the Aqua satellite, along with validation campaign data and underflight Scanning High-Resolution Interferometer (S-HIS) zenith and nadir spectra taken aboard a high-altitude aircraft. Retrieval sensitivity analyses have been performed for AIRS and the Infrared Interferometer Sounder (IRIS-D, 1970-1971) instruments. It is anticipated that the large changes in stratospheric temperature and CO2 values between the two missions would lead to detectable changes in the CO2 radiative forcing at the tropopause so long as the IRIS-D instrument could be appropriately characterized.

Feldman, D.; Liou, K.; Yung, Y.; Tobin, D.; Berk, L.

2005-12-01

6

Radiation fluxes and canopy transmittance: Models and measurements inside a willow canopy  

NASA Astrophysics Data System (ADS)

Upward and downward fluxes of photosynthetically active and broadband solar radiation, and the transmittance of direct solar radiation measured at different heights inside a willow (Salix viminalis) canopy are compared with modeling results. Two approaches are used for modeling the radiation field inside the canopy: solving the radiative transfer equation using the exact kernel discrete ordinates method and a Monte Carlo model. The measured and modeled canopies include a 1-year-old willow coppice with leaf area index (LAI) = 5 and a 4-year-old coppice with LAI = 8. Biometrical data used in the models are taken from detailed measurements of canopy structure; measured fluxes are used as boundary conditions. An attempt is made to include the effect of clumping on the penetration of direct solar radiation into the radiative transfer model. All models agreed well with measurement results; enhancement of modeled fluxes due to inclusion of clumping depended on the height inside the canopy while the distribution of leaf inclination angle had a minimal effect on the radiation regime of the stand.

Mõttus, Matti; Sulev, Madis

2006-01-01

7

Measurements of x-ray spectral flux and intensity distribution of APS/CHESS undulator radiation.  

National Technical Information Service (NTIS)

Absolute radiation flux and polarization measurements of the APS undulators may have to be made under high thermal loading conditions. A method that may circumvent the high-heat-load problem was tested during a recent APS/CHESS undulator run. The techniqu...

P. Ilinski W. Yun B. Lai E. Gluskin Z. Cai

1994-01-01

8

Retrieval of radiation fluxes from tilted wide field-of-view radiometer measurements  

NASA Astrophysics Data System (ADS)

The wide field-of-view radiometers aboard the Earth Radiation Budget Satellite operated for 15 years to provide a high quality radiation budget data set for climate research. Following a solar calibration, the radiometers did not return to Earth viewing position, but stopped short of nadir. Since that time, five years of measurements have been taken. Calibrations have been performed by use of special spacecraft maneuvers so that the measurements are well-calibrated. This paper presents the development of algorithms for retrieving the radiation fluxes at the "top of the atmosphere" taking into account the tilt of the WFOV radiometers from nadir.

Smith, G. Louis; Bush, Kathryn A.

2005-10-01

9

Measurements of x-ray spectral flux and intensity distribution of APS/CHESS undulator radiation  

SciTech Connect

Absolute radiation flux and polarization measurements of the APS undulators may have to be made under high thermal loading conditions. A method that may circumvent the high-heat-load problem was tested during a recent APS/CHESS undulator run. The technique makes use of a Si(Li) energy-dispersive detector to measure 5--35 keV x-rays scattered from a well-defined He gas volume at controlled pressure.

Ilinski, P.; Yun, W.; Lai, B.; Gluskin, E.; Cai, Z.

1994-09-01

10

Fast Longwave and Shortwave Radiative Fluxes (FLASHFlux) From CERES and MODIS Measurements  

NASA Astrophysics Data System (ADS)

The Clouds and the Earth's Radiant Energy System (CERES) project is currently producing highly accurate surface and top-of-atmosphere (TOA) radiation budget datasets from measurements taken by CERES broadband radiometers and a subset of imaging channels on the Moderate-resolution Imaging Spectroradiometer (MODIS) instrument operating onboard Terra and Aqua satellites. The primary objective of CERES is to produce highly accurate and stable time-series datasets of radiation budget parameters to meet the needs of climate change research. Accomplishing such accuracy and stability requires monitoring the calibration and stability of the instruments, maintaining constancy of processing algorithms and meteorological inputs, and extensively validating the products against independent measurements. Such stringent requirements inevitably delay the release of products to the user community by as much as six months to a year. While such delays are inconsequential for climate research, other applications like short-term and seasonal predictions, agricultural and solar energy research, ocean and atmosphere assimilation, and field experiment support could greatly benefit if CERES products were available quickly after satellite measurements. To meet the needs of the latter class of applications, FLASHFlux was developed and is being implemented at the NASA/LaRC. FLASHFlux produces reliable surface and TOA radiative parameters within a one week of satellite observations using CERES "quicklook" data stream and fast surface flux algorithms. Cloud properties used in flux computation are derived concurrently using MODIS channel radiances. In the process, a modest degree of accuracy is sacrificed in the interest of speed. All fluxes are derived initially on a CERES footprint basis. Daily average fluxes are then derived on a 1° x1° grid in the next stage of processing. To date, FLASHFlux datasets have been used in operational processing of CloudSat data, in support of a field experiment, and for the S'COOL education outreach program. In this presentation, examples will be presented of footprint level and gridded/daily averaged fluxes and their validation. FLASHFlux datasets are available to the science community at the LaRC Atmospheric Sciences Data Center (ASDC) at: eosweb.larc.nasa.gov/PRODOCS/flashflux/table flashflux.html.

Stackhouse, Paul; Gupta, Shashi; Kratz, David; Geier, Erika; Edwards, Anne; Wilber, Anne

11

Spectrally resolved fluxes and cloud radiative forcing from collocated AIRS and CERES measurements: derivation and application in climate studies  

Microsoft Academic Search

Spectrally resolved outgoing thermal-IR flux and cloud radiative forcing (CRF) have unique values in climate studies and evaluating climate model simulations. Here we describe an algorithm for deriving such spectral flux and spectral CRF through the entire thermal-IR spectrum from the collocated Atmospheric Infrared Sounder (AIRS) and the Clouds & the Earth's Radiant Energy System (CERES) measurements over the tropical

X. Huang; W. Yang; N. G. Loeb; V. Ramaswamy

2007-01-01

12

Measured radiation damage in charge coupled devices exposed to simulated deep orbit proton fluxes  

NASA Astrophysics Data System (ADS)

Measurements were made to quantify the effects of radiation damage in large area, deep-depletion CCDs developed for the joint European X-ray telescope (JET-X). Two devices were tested - the first, a standard X-ray CCD and the second, otherwise identical, including supplementary buried channels to improve its radiation hardness. Both devices were exposed to the expected in-orbit proton fluxes at the proton irradiation facility (PIF) at the Paul Scherrer Institute. The experimental conditions included the predicted orbital energy spectrum, its evolution and the proposed JET-X proton shielding. Energy resolution and charge transfer efficiency were measured after exposure to incremental doses corresponding to 0.25, 0.5, 1, 2 and 5 years in orbit. The radiation-hard device performed substantially better than the conventional device, showing a 20% degradation in energy resolution after 5 years equivalent dose (corresponding to ~ 109 protons cm-2), as compared to ~ 60% for the conventional device. Finally, the devices were exposed to fluences appropriate to the August 1972 solar flare. These results have been used to develop a model to predict the fwhm energy resolution of radiation damaged CCD.

Owens, Alan; McCarthy, Kieran J.; Wells, Alan; Hajdas, Wojtek; Mattenberger, Felix; Zehnder, Alex; Terekhov, Oleg

1995-02-01

13

Pulse flux measuring device  

DOEpatents

A device for measuring particle flux comprises first and second photodiode detectors for receiving flux from a source and first and second outputs for producing first and second signals representing the flux incident to the detectors. The device is capable of reducing the first output signal by a portion of the second output signal, thereby enhancing the accuracy of the device. Devices in accordance with the invention may measure distinct components of flux from a single source or fluxes from several sources.

Riggan, William C. (Albuquerque, NM)

1985-01-01

14

Measuring True Temperatures Via Polarized Radiation Fluxes in Visible Range of the Spectrum.  

National Technical Information Service (NTIS)

A method for measuring the true temperature by the relative spectral density distribution of polarized radiation is proposed. One simple version of the technical realization of this method is measurement of the true temperature by the ratio of parallel co...

D. Y. Svet V. I. Sayapina

1970-01-01

15

Solar and Thermal Radiation Flux Measurements over the East Coast of Australia  

Microsoft Academic Search

Aircraft measurements show that the albedo of much of the east coast of Australia may be described in terms of only two curves of albedo versus solar elevation (A rs. e), those of eucalypt forest and dry grassland. The theoretical albedo of white-capping sea to isotropic sky radiation (derived from an experimental A rs. e curve) is found to be

G. W. Paltridge

1971-01-01

16

Measurement and modeling of vertically resolved aerosol optical properties and radiative fluxes over the ARM SGP site  

NASA Astrophysics Data System (ADS)

In order to meet one of its goals - to relate observations of radiative fluxes and radiances to the atmospheric composition - the Department of Energy's Atmospheric Radiation Measurement (ARM) program has pursued measurements and modeling activities that attempt to determine how aerosols impact atmospheric radiative transfer, both directly and indirectly. However, significant discrepancies between aerosol properties measured in situ or remotely remain. One of the objectives of the Aerosol Intensive Operational Period (IOP) conducted by ARM in May 2003 at the ARM Southern Great Plains (SGP) site in north central Oklahoma was to examine and hopefully reduce these differences. The IOP involved airborne measurements from two airplanes over the heavily instrumented SGP site. We give an overview of airborne results obtained aboard the Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter aircraft. The Twin Otter performed 16 research flights over the SGP site. The aircraft carried instrumentation to perform in-situ measurements of aerosol absorption, scattering, extinction and particle size. This included such novel techniques as the photoacoustic and cavity ring-down methods for in-situ absorption (675 nm) and extinction (675 and 1550 nm) and a new multiwavelength, filter-based absorption photometer (467, 530, 660 nm). A newly developed instrument measured cloud condensation nucleus concentration (CCN) concentrations at two supersaturation levels. Aerosol optical depth and extinction (354-2139 nm) were measured with the NASA Ames Airborne Tracking 14-channel sunphotometer. Furthermore, up- and downwelling solar (broadband and spectral) and infrared radiation were measured using seven individual radiometers. Three up-looking radiometers were mounted on a newly developed stabilized platform, keeping the instruments level up to aircraft pitch and roll angles of ˜10° . This resulted in unprecedented continuous vertical profiles of radiative fluxes, which we will compare to modeled fluxes using the aforementioned data as input. We will also present comparisons of the vertically resolved aerosol optical properties measured aboard the Twin Otter and from two ground-based lidar systems. Finally we use a trajectory model and a three-dimensional aerosol transport and microphysics model to explore the long-range transport and evolution of smoke aerosols from Siberian fires observed over SGP May 25-28, 2003.

Schmid, B.; Arnott, W.; Bucholtz, A.; Colarco, P.; Covert, D.; Eilers, J.; Elleman, R.; Ferrare, R.; Flagan, R.; Jonsson, H.; Pilewskie, P.; Pommier, J.; Redemann, J.; Ricci, K.; Rissman, T.; Seinfeld, J.; Strawa, A.; Vanreken, T.; Wang, J.; Welton, E.

2003-12-01

17

A Method for Continuous Estimation of Clear-Sky Downwelling Longwave Radiative Flux Developed Using ARM Surface Measurements.  

SciTech Connect

We present a methodology for the continuous estimation of downwelling clear-sky longwave (LW) radiative flux based on analysis of surface irradiance, air temperature, and humidity measurements. While there is no exact means of determining the uncertainty associated with the clear-sky LW estimations, our analyses and comparison with detailed radiative transfer model calculations suggest that our estimations on average are no worse than model calculations that require temporally and spatially averaged input information. Our technique exhibits a high degree of repeatability for the downwelling LW cloud effect, with agreement at about the 3 Wm-2 level even including the results for a measurement system with a known calibration offset problem. Applying our technique, as well as that of Long and Ackerman (2000) for the shortwave (SW) radiative flux, to 15 years of data from the Atmospheric Radiation Measurement Program Southern Great Plains site shows that the maximum downwelling LW lags the SW maximum by about a month on yearly time scales, and by about 3 hours diurnally. The maximum all-sky and clear-sky SW and LW occurs during the summer months, with the greatest year-to-year clear-sky SW variability occurring in the fall, but the yearto-year clear- and all-sky LW variability is about the same in all seasons. The downwelling LW cloud effect is fairly constant in the aggregate across the seasons, but the greatest SW cloud effect occurs in the spring. Overall, the downwelling net cloud effect is dominated by the SW, with the greatest decrease in radiative energy reaching the surface due to clouds occurring in the spring (-64 Wm-2), and the smallest magnitude net cloud effect occurring during winter (-21 Wm-2).

Long, Charles N.; Turner, David D.

2008-09-30

18

Fast Longwave and Shortwave Radiative Fluxes (FLASHFlux) From CERES and MODIS Measurements  

Microsoft Academic Search

The Clouds and the Earth's Radiant Energy System (CERES) project is currently producing highly accurate surface and top-of-atmosphere (TOA) radiation budget datasets from measurements taken by CERES broadband radiometers and a subset of imaging channels on the Moderate-resolution Imaging Spectroradiometer (MODIS) instrument operating onboard Terra and Aqua satellites. The primary objective of CERES is to produce highly accurate and stable

Paul Stackhouse; Shashi Gupta; David Kratz; Erika Geier; Anne Edwards; Anne Wilber

2008-01-01

19

Results of a Comprehensive Atmospheric Aerosol-Radiation Experiment in the Southwestern United States. Part II: Radiation Flux Measurements and Theoretical Interpretation  

Microsoft Academic Search

The experimental results in Part I are used in the theoretical interpretation of the radiation flux measurements which were taken with an aircraft. The absorption term of the complex refractive index of aerosols is estimated to be approximately 0.01 for a real part of 1.5 for the wavelength bandwidth 0.32-0.68 m. A regional variation in the refractive index is noted.Atmospheric

J. J. Deluisi; P. M. Furukawa; D. A. Gillette; B. G. Schuster; R. J. Charlson; W. M. Porch; R. W. Fegley; B. M. Herman; R. A. Rabinoff; J. T. Twitty; J. A. Weinman

1976-01-01

20

Apparatus for measuring high-flux heat transfer in radiatively heated compact exchangers  

SciTech Connect

Described is an apparatus which can deliver uniform heat flux densities of up to 80 W/sq cm over an area 7.8 cm by 15.2 cm for use in measuring the heat transfer and pressure drop in thin (6 mm or less), compact heat exchangers. Helium gas at flow rates of 0 to 40 kg/h and pressures to 6.9 MPa (1000 psi) is the working fluid. The instrumentation used in the apparatus and the methods for analyzing the data is described. The apparatus will be used initially to test the performance of prototype cooling jackets for the engine struts of the National Aerospace Plane (NASP).

Olson, D.A.

1989-10-01

21

Measured and calculated clear-sky solar radiative fluxes during the Subsonic Aircraft Contrail and Cloud Effects Special Study (SUCCESS)  

SciTech Connect

Modeled and measured surface insolations are compared with the purpose of evaluating the ability of a radiative transfer model to predict the amount of solar radiation reaching the surface under clear-sky conditions. Model uncertainties are estimated by performing sensitivity studies for variations in aerosol optical depth, aerosol optical properties, water vapor profiles, ozone content, solar irradiance at the top of the atmosphere, and surface albedo. In this fashion, a range of possible calculated values is determined and compared to observations. Experimental errors are evaluated by comparison with independent, simultaneous measurements performed using two World Radiation Reference instrument arrays that were operational for a limited period during SUCCESS. Assuming a mineral aerosol, it is found that there is agreement between calculated and measured fluxes, with differences approximately equal to and within one standard deviation. Such agreement improves further if a layer containing a small amount of carbonaceous aerosol is added. The presence of carbonaceous aerosols is likely because occasional biomass burning activities took place during SUCCESS in the area around the experimental site (the clouds and radiation test bed operated by the Department of Energy in Oklahoma). (c) 2000 American Geophysical Union.

Valero, Francisco P. J. [Atmospheric Research Laboratory, Center for Atmospheric Sciences, Scripps Institution of Oceanography, University of California, San Diego, California (United States); Bush, Brett C. [Atmospheric Research Laboratory, Center for Atmospheric Sciences, Scripps Institution of Oceanography, University of California, San Diego, California (United States)

1999-11-27

22

Measurements of net radiation, ground heat flux and surface temperature in an urban canyon  

SciTech Connect

The Joint Urban 2003 (JU2003) field study was conducted in Oklahoma City in July 2003 to collect data to increase our knowledge of dispersion in urban areas. Air motions in and around urban areas are very complicated due to the influence of urban structures on both mechanical and thermal forcing. During JU2003, meteorological instruments were deployed at various locations throughout the urban area to characterize the processes that influence dispersion. Some of the instruments were deployed to characterize urban phenomena, such as boundary layer development. In addition, particular sites were chosen for more concentrated measurements to investigate physical processes in more detail. One such site was an urban street canyon on Park Avenue between Broadway and Robinson Avenues in downtown Oklahoma City. The urban canyon study was designed to examine the processes that control dispersion within, into and out of the urban canyon. Several towers were deployed in the Park Avenue block, with multiple levels on each tower for observing the wind using sonic anemometers. Infrared thermometers, net radiometers and ground heat flux plates were deployed on two of the towers midway in the canyon to study the thermodynamic effects and to estimate the surface energy balance. We present results from the surface energy balance observations.

Gouveia, F J; Leach, M J; Shinn, J H

2003-11-06

23

A method for continuous estimation of clear-sky downwelling longwave radiative flux developed using ARM surface measurements  

NASA Astrophysics Data System (ADS)

We present an improved self-adaptive methodology for the continuous estimation of downwelling clear-sky longwave (LW) radiative flux based on analysis of surface irradiance, air temperature, and humidity measurements that includes a term to account for near surface optically thin haze. Comparison between our estimations and clear-sky LW measurements for many years of data from the Atmospheric Radiation Measurement (ARM) Climate Research Facility's Southern Great Plains (SGP), Tropical Western Pacific (TWP), and North Slope of Alaska (NSA) sites show agreement at about the 4 W m-2 level, with 75%, 94%, and 68% of the data falling within that range for the SGP, TWP, and NSA sites, respectively. Although there is no exact means of determining the uncertainty associated with the clear-sky LW estimations, our analyses and comparison with detailed radiative transfer (RT) model calculations suggest our estimations on average are no worse than model calculations that require temporally and spatially averaged input information. Our technique exhibits a high degree of repeatability for the downwelling LW cloud effect, with agreement at about the 3 W m-2 level. Applying our technique and that of Long and Ackerman (2000) to 15 years of data from the ARM SGP site shows the maximum all-sky and clear-sky SW and LW occurs during summer, with the greatest year-to-year clear-sky SW variability occurring in fall. The downwelling LW cloud effect is fairly constant across the seasons, but the greatest SW cloud effect occurs in spring. The downwelling net cloud effect is dominated by the SW, with the largest effect occurring in spring (-64 W m-2) and the smallest occurring during winter (-21 W m-2).

Long, C. N.; Turner, D. D.

2008-09-01

24

Cosmic Ray Neutron Flux Measurements  

NASA Astrophysics Data System (ADS)

Cosmic rays are high-energetic particles originating from outer space that bombard the upper atmosphere of the Earth. Almost 90% of cosmic ray particles consist of protons, electrons and heavy ions. When these particles hit the Earth's atmosphere, cascade of secondary particles are formed. The most abundant particles reach to the surface of the Earth are muons, electrons and neutrons. In recent years many research groups are looking into potential applications of the effects of cosmic ray radiation at the surface of the Earth [1, 2]. At Georgia State University we are working on a long-term measurement of cosmic ray flux distribution. This study includes the simultaneous measurement of cosmic ray muons, neutrons and gamma particles at the Earth surface in downtown Atlanta. The initial effort is focusing on the correlation studies of the cosmic ray particle flux distribution and the atmospheric weather conditions. In this presentation, I will talk about the development of a cosmic ray detector using liquid scintillator and the preliminary results. [4pt] [1] K.Borozdin, G.Hogan, C.Morris, W.Priedhorsky, A.Saunders, L.Shultz, M.Teasdale, ``Radiographic imaging with cosmic-ray muons'', Nature, Vol.422, p.277, Mar.2003[0pt] [2] Svensmark Henrik, Physical Review 81, 3, (1998)

Dayananda, Mathes

2009-11-01

25

Polar Radiation-Flux Symmetry Measurements in Z-Pinch-Driven Hohlraums with Symmetric Double-Pinch Drive  

NASA Astrophysics Data System (ADS)

We are currently exploring symmetry requirements of the z-pinch-driven hohlraum concept [1] for high-yield inertial confinement fusion. In experiments on the Z accelerator, the burnthrough of a low-density self-backlit foam ball has been used to diagnose the large time-dependent flux asymmetry of several single-sided-drive hohlraum geometries [2]. We are currently applying this technique to study polar radiation flux symmetry in a symmetric double z-pinch geometry. Wire arrays on opposite ends of the hohlraum, connected in series to a single current drive of 18 MA, implode and stagnate on axis, efficiently radiating about 100 TW of x rays which heat the secondary to 75 eV. Comparisons with 3-D radiosity and 2-D rad-hydro models of hohlraum symmetry performance will be presented. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DE-AC04-94AL85000. 1 J. H. Hammer et al., Phys. Plasmas 6, 2129 (1999). 2 D. L. Hanson et al., Bull. Am. Phys. Soc. 44, 40 (1999).

Hanson, D. L.; Vesey, R. A.; Cuneo Porter, M. E., Jr.; Chandler, G. A.; Ruggles, L. E.; Simpson, W. W.; Seamen, H.; Primm, P.; Torres, J.; McGurn, J.; Gilliland, T. L.; Reynolds, P.; Hebron, D. E.; Dropinski, S. C.; Schroen-Carey, D. G.; Hammer, J. H.; Landen, O.; Koch, J.

2000-10-01

26

New Measurement of the Antiproton-to-Proton Flux Ratio up to 100 GeV in the Cosmic Radiation  

Microsoft Academic Search

A new measurement of the cosmic-ray antiproton-to-proton flux ratio between 1 and 100 GeV is presented. The results were obtained with the PAMELA experiment, which was launched into low-Earth orbit on-board the Resurs-DK1 satellite on June 15th 2006. During 500 days of data collection a total of about 1000 antiprotons have been identified, including 100 above an energy of 20

O. Adriani; G. C. Barbarino; G. A. Bazilevskaya; R. Bellotti; M. Boezio; E. A. Bogomolov; L. Bonechi; M. Bongi; V. Bonvicini; S. Bottai; A. Bruno; F. Cafagna; D. Campana; P. Carlson; M. Casolino; G. Castellini; M. P. de Pascale; G. de Rosa; D. Fedele; A. M. Galper; L. Grishantseva; P. Hofverberg; A. Leonov; S. V. Koldashov; S. Y. Krutkov; A. N. Kvashnin; V. Malvezzi; L. Marcelli; W. Menn; V. V. Mikhailov; M. Minori; E. Mocchiutti; M. Nagni; S. Orsi; G. Osteria; P. Papini; M. Pearce; P. Picozza; M. Ricci; S. B. Ricciarini; M. Simon; R. Sparvoli; P. Spillantini; Y. I. Stozhkov; E. Taddei; A. Vacchi; E. Vannuccini; G. Vasilyev; S. A. Voronov; Y. T. Yurkin; G. Zampa; N. Zampa; V. G. Zverev

2009-01-01

27

RADIATION FROM COMOVING POYNTING FLUX ACCELERATION  

SciTech Connect

We derive analytic formulas for the radiation power output when electrons are accelerated by a relativistic comoving kinetic Poynting flux, and validate these analytic results with particle-in-cell simulations. We also derive analytically the critical frequency of the radiation spectrum. Potential astrophysical applications of these results are discussed. A quantitative model of gamma-ray bursts based on the breakout of kinetic Poynting flux is presented.

Liang, Edison; Noguchi, Koichi [Rice University, Houston TX 77005-1892 (United States)

2009-11-10

28

New measurement of the antiproton-to-proton flux ratio up to 100 GeV in the cosmic radiation.  

PubMed

A new measurement of the cosmic-ray antiproton-to-proton flux ratio between 1 and 100 GeV is presented. The results were obtained with the PAMELA experiment, which was launched into low-Earth orbit on-board the Resurs-DK1 satellite on June 15th 2006. During 500 days of data collection a total of about 1000 antiprotons have been identified, including 100 above an energy of 20 GeV. The high-energy results are a tenfold improvement in statistics with respect to all previously published data. The data follow the trend expected from secondary production calculations and significantly constrain contributions from exotic sources, e.g., dark matter particle annihilations. PMID:19257498

Adriani, O; Barbarino, G C; Bazilevskaya, G A; Bellotti, R; Boezio, M; Bogomolov, E A; Bonechi, L; Bongi, M; Bonvicini, V; Bottai, S; Bruno, A; Cafagna, F; Campana, D; Carlson, P; Casolino, M; Castellini, G; De Pascale, M P; De Rosa, G; Fedele, D; Galper, A M; Grishantseva, L; Hofverberg, P; Leonov, A; Koldashov, S V; Krutkov, S Y; Kvashnin, A N; Malvezzi, V; Marcelli, L; Menn, W; Mikhailov, V V; Minori, M; Mocchiutti, E; Nagni, M; Orsi, S; Osteria, G; Papini, P; Pearce, M; Picozza, P; Ricci, M; Ricciarini, S B; Simon, M; Sparvoli, R; Spillantini, P; Stozhkov, Y I; Taddei, E; Vacchi, A; Vannuccini, E; Vasilyev, G; Voronov, S A; Yurkin, Y T; Zampa, G; Zampa, N; Zverev, V G

2009-02-02

29

Impact of the monsoon on downwelling surface radiative fluxes across West Africa : an evaluation of ECMWF-IFS and satellite estimates with ground measurements  

NASA Astrophysics Data System (ADS)

Land-atmosphere exchanges are key for both land and atmospheric processes, and are affected by various feedback loops between these processes. This study focusses on downwelling surface radiation fluxes (DSRF), which represent a major forcing for land surface models (LSM) as well as a challenge for atmospheric models. Besides seasonal insolation, DSRF depend on such characteristics as cloud coverage and type, air temperature and humidity, and atmospheric aerosols. Flux estimations are provided from model or remote-sensing (RS) estimates, at space resolutions of several kms to several tens of kms. Direct observation in the field can be made by networks of point measurements. In West Africa, very few ground data have so far been available, hence little validation of model or RS estimates has yet been undertaken. In this region, radiative fluxes are strongly impacted by the West African monsoon (WAM) processes and by dust events of considerable importance, which are still insufficiently understood and modelled. As part of the AMMA programme (African monsoon multidisciplinary analyses), a network of surface flux data, including radiation components, was installed along a latitudinal transect across West Africa, making possible the comparison of available DSRF estimates with this new in-situ data. Such evaluation is key both for ensuring adequate forcing of LSMs such as those involved in the AMMA LSM intercomparison project (ALMIP), and for validating of atmospheric models and RS retrieval algorithms. In the AMMA surface flux network, 3 stations in Benin (~9.8°N), 4 in Niger (~13.5°N), and 4 in Mali (between 15.3 and 17°N) provide DSRF data. In this communication, results are presented for 2006, the year of AMMA's special observation periods. Seasonal, latitudinal and intra-site variability is highlighted and discussed. If DSRF variations are generally consistent with the solar course during the first months in the year, this relationship degrades when the WAM sets in. Thus the WAM stands as a major actor in shaping the seasonal cycle of DSRF. It is found to affect shortwave and longwave downwelling fluxes in distinct ways across latitude, from the more cloudy Soudanian zone up to the margins of the Sahara in the northern Sahel. In-situ DSRF data are compared with estimated values from the ECMWF-IFS and from the ALMIP database (corresponding to LAND-SAF satellite estimates) at each site. The pre-monsoon period is especially investigated, as it is characterized by the occurrence of numerous dust events, squall lines, a rise in atmospheric humidity, and cloud coverage. These conditions favour errors in DSRF estimates.

Ramier, D.; Guichard, F.; Cappelaere, B.; Kergoat, L.; Galle, S.; Timouk, F.; Boulain, N.; Boucher, M.; Taylor, C.; Boone, A.

2009-04-01

30

RADIATION MEASURING DEVICES  

DOEpatents

A radiation-measuring device is described having an a-c output. The apparatus has a high-energy particle source responsive to radiation flux disposed within a housing having a pair of collector plates. A potential gradient between the source and collector plates causes ions to flow to the plates. By means of electrostatic or magnetic deflection elements connected to an alternating potential, the ions are caused to flow alternately to each of the collector plates causing an a-c signal thereon.

Bouricius, G.M.B.; Rusch, G.K.

1960-03-22

31

IR thermography heat flux measurement in fire safety applications  

NASA Astrophysics Data System (ADS)

The paper deals with heat flux measurement possibilities in fire safety applications. The paper presents two methods for radiation heat flux measurement - the thermography source-target measurement method, and the radiation contact target measurement method. Both the methods were used simultaneously for radiation heat flux measurement during a fire experiment on a high-density polyethylene plastic box storage stack. The theoretical background, experimental set-up, application example, and comparison of both methods are presented in this paper. Dependence of heat flux magnitude on a distance and direction from a heat source is evaluated. The possible safety risks ensuing from high temperatures inside the burning stack, and therefore high heat fluxes near the stack, are discussed.

Švantner, Michal; Vacíková, Petra; Honner, Milan

2012-07-01

32

ANISOTROPIC COSMIC RADIATION FLUXES OF SOLAR ORIGIN  

Microsoft Academic Search

portant features of three cosmic-ray flare effects that were observed during the first thirty days of the flight of the Pioneer 6 spacecraft. It has been found that the cosmic radiation flux of mean energy 13 Mev\\/nucleon exhibited an extremely anisotropic character throughout each flare effect, the anisotropy persisting for in excess of 48 hours during one event. Subsequent flare

W. C. Bartley; R. P. Bukata; K. G. McCracken; U. R. Rao

1966-01-01

33

Measuring Radiation  

MedlinePLUS

... are four different but interrelated units for measuring radioactivity, exposure, absorbed dose, and dose equivalent. These can ... radioactive material is expressed in terms of its radioactivity (or simply its activity), which represents how many ...

34

Net radiation — soil heat flux relations as influenced by soil water content variations  

Microsoft Academic Search

Net radiation, soil heat flux, incoming and reflected solar radiation, and soil water content were measured during several clear day periods following approximate 10-cm applications of water to loam soils at Phoenix, Arizona, and at Sidney, Montana. The regression of soil heat flux on net radiation changed significantly as the soil dried, with the difference between them being a linear

S. B. Idso; J. K. Aase; R. D. Jackson

1975-01-01

35

Spectral estimates of net radiation and soil heat flux  

USGS Publications Warehouse

Conventional methods of measuring surface energy balance are point measurements and represent only a small area. Remote sensing offers a potential means of measuring outgoing fluxes over large areas at the spatial resolution of the sensor. The objective of this study was to estimate net radiation (Rn) and soil heat flux (G) using remotely sensed multispectral data acquired from an aircraft over large agricultural fields. Ground-based instruments measured Rn and G at nine locations along the flight lines. Incoming fluxes were also measured by ground-based instruments. Outgoing fluxes were estimated using remotely sensed data. Remote Rn, estimated as the algebraic sum of incoming and outgoing fluxes, slightly underestimated Rn measured by the ground-based net radiometers. The mean absolute errors for remote Rn minus measured Rn were less than 7%. Remote G, estimated as a function of a spectral vegetation index and remote Rn, slightly overestimated measured G; however, the mean absolute error for remote G was 13%. Some of the differences between measured and remote values of Rn and G are associated with differences in instrument designs and measurement techniques. The root mean square error for available energy (Rn - G) was 12%. Thus, methods using both ground-based and remotely sensed data can provide reliable estimates of the available energy which can be partitioned into sensible and latent heat under nonadvective conditions. ?? 1990.

Daughtry, C. S. T.; Kustas, W. P.; Moran, M. S.; Pinter, Jr. , P. J.; Jackson, R. D.; Brown, P. W.; Nichols, W. D.; Gay, L. W.

1990-01-01

36

Skyglow effects in UV and visible spectra: radiative fluxes.  

PubMed

Several studies have tried to understand the mechanisms and effects of radiative transfer under different night-sky conditions. However, most of these studies are limited to the various effects of visible spectra. Nevertheless, the invisible parts of the electromagnetic spectrum can pose a more profound threat to nature. One visible threat is from what is popularly termed skyglow. Such skyglow is caused by injudiciously situated or designed artificial night lighting systems which degrade desired sky viewing. Therefore, since lamp emissions are not limited to visible electromagnetic spectra, it is necessary to consider the complete spectrum of such lamps in order to understand the physical behaviour of diffuse radiation at terrain level. In this paper, the downward diffuse radiative flux is computed in a two-stream approximation and obtained ultraviolet spectral radiative fluxes are inter-related with luminous fluxes. Such a method then permits an estimate of ultraviolet radiation if the traditionally measured illuminance on a horizontal plane is available. The utility of such a comparison of two spectral bands is shown, using the different lamp types employed in street lighting. The data demonstrate that it is insufficient to specify lamp type and its visible flux production independently of each other. Also the UV emissions have to be treated by modellers and environmental scientists because some light sources can be fairly important pollutants in the near ultraviolet. Such light sources can affect both the living organisms and ambient environment. PMID:23792881

Kocifaj, Miroslav; Solano Lamphar, H A

2013-06-21

37

Simulation Study of a Geometric Shape Factor Technique for Estimating Earth-Emitted Radiant Flux Densities from Wide-Field-of-View Radiation Measurements.  

National Technical Information Service (NTIS)

Geometric shape factors were computed and applied to satellite simulated irradiance measurements to estimate Earth emitted flux densities for global and zonal scales and for areas smaller than the detector field of view (FOV). Wide field of view flat plat...

W. L. Weaver R. N. Green

1980-01-01

38

Latent Heat in Soil Heat Flux Measurements  

Technology Transfer Automated Retrieval System (TEKTRAN)

The surface energy balance includes a term for soil heat flux. Soil heat flux is difficult to measure because it includes conduction and convection heat transfer processes. Accurate representation of soil heat flux is an important consideration in many modeling and measurement applications. Yet, the...

39

Radiative flux calculations at UV and visible wavelengths  

SciTech Connect

A radiative transfer model to calculate the short wavelength fluxes at altitudes between 0 and 80 km has been developed at LLNL. The wavelength range extends from 175--735 nm. This spectral range covers the UV-B wavelength region, 250--350 nm, with sufficient resolution to allow comparison of UV-B measurements with theoretical predictions. Validation studies for the model have been made for both UV-B ground radiation calculations and tropospheric solar radiative forcing calculations for various ozone distributions. These studies indicate that the model produces results which agree well with respect to existing UV calculations from other published models.

Grossman, A.S.; Grant, K.E.; Wuebbles, D.J.

1993-10-01

40

Sensitivity of Radiative Fluxes and Heating Rates To Cloud Microphysics  

NASA Astrophysics Data System (ADS)

We have investigated the sensitivity of modeled radiative fluxes to the specification of cloud microphysical parameterizations using a single-column model and measure- ments from the Atmospheric Radiation Measurement (ARM) Program. The single- column model was run for the three-month period of June-August, 2000 at the ARM Southern Great Plains and Tropical Western Pacific sites. At each site, the model was forced using 0-24 hour forecast products from the global spectral model of the U. S. National Centers for Environmental Prediction. Several model runs were performed, each with a different package of cloud microphysical parameterizations. The temporal evolution of modeled cloud amount as well as surface radiative fluxes from a control run compare well with ARM measurements at the Southern Great Plains site. The re- alism of the control run results at the Tropical West Pacific site is more difficult to evaluate due to the limited spatial resolution of the ARM observations there. Both surface and top-of-atmosphere radiative fluxes are sensitive to the scheme used to specify the ice particle effective radius. We also find that the inclusion of ice particle fallout can have a significant effect on the amount and location of high cirrus clouds. A particularly interesting finding is that the variance of the modeled ice particle effective radius is considerably smaller than that suggested by ARM cloud radar measurements at the Southern Great Plains site. This was the case for all four tested parameterizations of ice particle effective radius. Our preliminary results suggest that this theoretical underestimate of the ice particle effective radius variance can have significant effects on the modeled radiative fluxes due to the highly non-linear nature of cloud-radiation interactions.

Iacobellis, S. F.; Somerville, R. C. J.; McFarquhar, G. M.

41

Spatially averaged heat flux and convergence measurements at the ARM regional flux experiment  

SciTech Connect

Cloud formation and its relation to climate change is the greatest weakness in current numerical climate models. Surface heat flux in some cases causes clouds to form and in other to dissipate and the differences between these cases are subtle enough to make parameterization difficult in a numerical model. One of the goals of the DOE Atmospheric Radiation Measurement program is to make long term measurements at representative sites to improve radiation and cloud formation parameterization. This paper compares spatially averaged optical measurements of heat flux and convergence with a goal of determining how point measurements of heat fluxes scale up to the larger scale used for climate modeling. It was found that the various optical techniques used in this paper compared well with each other and with independent measurements. These results add confidence that spatially averaging optical techniques can be applied to transform point measurements to the larger scales needed for mesoscale and climate modeling. 10 refs., 6 figs. (MHB)

Porch, W.; Barnes, F.; Buchwald, M.; Clements, W.; Cooper, D.; Hoard, D. (Los Alamos National Lab., NM (United States)); Doran, C.; Hubbe, J.; Shaw, W. (Pacific Northwest Lab., Richland, WA (United States)); Coulter, R.; Martin, T. (Argonne National Lab., IL (United States)); Kunkel, K. (Illinois State Water Survey, Champaign, IL (United States))

1991-01-01

42

Generation of Toa Radiative Fluxes From The Gerb Instruments  

NASA Astrophysics Data System (ADS)

The first Meteosat Second Generation (MSG) satellite is planned to be launched in summer 2002. This EUMETSAT's satellite will carry 2 new instruments on a geo- stationary orbit: the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) and the Geostationary Earth Radiation Budget (GERB). The unique feature of GERB in comparison with previous measurements of the Earth's radiation budget (e.g. ERBE, ScaRab and CERES experiments) is the high temporal sampling afforded by the geo- stationary orbit, albeit for a limited region of the globe. The GERB will provide ac- curate broadband measurements of the radiant energy due to the reflection of the in- coming solar energy by the Earth-atmosphere system and due to the thermal emission within this system. The synergetic use of the SEVIRI data is needed to convert these directional measurements (radiances) into radiative fluxes at the top-of-atmosphere. Additionally, the SEVIRI data allows the enhancement of the spatial resolution of the GERB measurement. This contribution describes the near real-time GERB processing system that has been set up at RMIB. This includes the unfiltering of the instrument data, the radiance-to-flux conversion and the spatial resolution enhancement. The ex- pected accuracy on the resulting fluxes and their foreseen applications are also pre- sented.

Clerbaux, N.; Bertrand, C.; Dewitte, S.; Ipe, A.; Gonzalez, L.; Nicula, B.

43

RADIATION DOSIMETRY AT THE BNL HIGH FLUX BEAM REACTOR AND MEDICAL RESEARCH REACTOR  

Microsoft Academic Search

RADIATION DOSIMETRY MEASUREMENTS HAVE BEEN PERFORMED OVER A PERIOD OF MANY YEARS AT THE HIGH FLUX BEAM REACTOR (HFBR) AND THE MEDICAL RESEARCH REACTOR (BMRR) AT BROOKHAVEN NATIONAL LABORATORY TO PROVIDE INFORMATION ON THE ENERGY DISTRIBUTION OF THE NEUTRON FLUX, NEUTRON DOSE RATES, GAMMA-RAY FLUXES AND GAMMA-RAY DOSE RATES. THE MCNP PARTICLE TRANSPORT CODE PROVIDED MONTE CARLO RESULTS TO COMPARE

1999-01-01

44

A new approach of surface flux measurements using DTS  

NASA Astrophysics Data System (ADS)

Estimation of surface fluxes is a difficult task, especially over lakes. Determining latent heat flux (evaporation), sensible heat flux and ground heat flux involves measurements and (or calculations) of net radiation, air temperature, water temperature, wind speed and relative humidity. This research presents a new method to measure surface fluxes by means of Distributed Temperature Sensing (DTS). From 0.5 m above lake level to 1.5 m under lake level DTS was applied to measure temperature. Using a PVC hyperboloid construction, a floating standalone measuring device was developed. This new setup distinguished itself by the open construction, so it is almost insensitive to direct radiation. While most of the lake ground heat changes occur very close to the lake surface, most measuring methods only obtain rough results. With this construction it was possible to create a spiral shaped fiber-optic cable setup, with which a vertical spatial resolution of 0.02 m and a temporal resolution of 1 min was obtained. The new method was tested in the deep Lake Kinneret (Israel) from 6 October, 2011 to 11 October, 2011and in the shallow Lake Binaba (Ghana) from 24 October, 2011 to 28 October, 2011. This study shows that with the developed method it is possible to capture the energy fluxes within the top water layer with a high resolution. When the old low resolution method was compared with the new high resolution method, it could be concluded that the impact of the surface fluxes in the upper layer is high on the energy balance on a daily scale. During the measuring period it was possible to use the temperature measured by the DTS to determine the sensible heat flux, the latent heat flux and the ground heat flux of both lakes.

van Emmerik, T. H. M.; Wenker, K. J. R.; Rimmer, A.; de Jong, S. A. P.; Lechinsky, Y.; van de Giesen, N. C.

2012-04-01

45

Decadal Changes in Surface Radiative Fluxes  

NASA Astrophysics Data System (ADS)

Recent evidence suggests that radiative fluxes incident at the Earth surface are not stable over time but undergo significant changes on decadal timescales. This is not only found in the thermal spectral range, where an increase in the downwelling flux is expected with the increasing greenhouse effect, but also in the solar range. Observations suggest that surface solar radiation, after decades of decline ("global dimming"), reversed into a "brightening" since the mid-1980s at widespread locations. This presentation gives an update on recent investigations related to the decadal variations in these fluxes, based on both observational and modeling approaches. Updated observational data, archived at the Global Energy Balance Archive (GEBA) at ETH Zurich, suggest a continuation of surface solar brightening beyond the year 2000 at numerous locations, yet less pronounced and coherent than during the 1990s, with more regions with no clear changes or declines. Current global climate models as used in the IPCC-AR4 report typically do not reproduce the observed decadal variations to their full extent. Modeling attempts to improve this situation are under way at ETH, based on a global climate model which includes a sophisticated interactive treatment of aerosol and cloud microphysics (ECHAM5-HAM). Further the impact of the decadal changes in surface radiative forcings on different aspects of the global climate system and climate change is discussed, such as 20th century day- and nighttime warming, evapotranspiration changes and the varying intensity of the hydrological cycle as well as the terrestrial carbon cycle. Selected related references: Wild, M., and Co-authors, 2005: From dimming to brightening: Decadal changes in solar radiation at the Earth's surface. Science, 308, 847-850 Wild, M., 2007: Decadal changes in surface radiative fluxes and their importance in the context of global climate change, in: Climate Variability and Extremes during the Past 100 years, Advances in Global Change Research, 140, Editors Stefan Brönnimann et al., p. 155-168. Wild, M., Ohmura A., Makowski, K., 2007: Impact of global dimming and brightening on global warming. Geophys. Res. Lett., 34, L04702, doi:10.1029/2006GL028031. Wild, M., Grieser, J. and Schär, C., 2008: Combined surface solar brightening and greenhouse effect support recent intensification of the global land-based hydrological cycle. Geophys. Res. Lett., 35, L17706, doi:10.1029/2008GL034842 Wild, M., 2009: How well do IPCC-AR4/CMIP3 climate models simulate global dimming/brightening and 20th century day- and night-time warming? To appear in J. Geophys. Res. Wild, M., Truessel, B., Ohmura, A., Long, C.N. König-Langlo G., Dutton, E.G., and Tsvetkov, A., 2009: Global Dimming and Brightening: an update beyond 2000. To appear in J. Geophys. Res. Wild, M., 2009: Global dimming and brightening: A review on decadal changes in surface solar radiation. To appear in J. Geophys. Res.

Wild, M.

2009-05-01

46

Sensitivity of shortwave radiative flux density, forcing, and heating rate to the aerosol vertical profile  

Microsoft Academic Search

The effect of the aerosol vertical distribution on the solar radiation profiles for idealized and measured profiles of extinction and single-scattering albedo (SSA) during the May 2003 Atmospheric Radiation Measurement Aerosol Intensive Observation Period (AIOP) is investigated using the rapid radiative transfer model shortwave code. Calculated profiles of downwelling and upwelling solar flux density during the AIOP are compared with

Hong Guan; Beat Schmid; Anthony Bucholtz; Robert Bergstrom

2010-01-01

47

Regional carbon dioxide fluxes from aircraft measurements in southwest France  

NASA Astrophysics Data System (ADS)

In 2007, the CarboEurope-IP Regional Component organised the second edition of the CERES measurement campaign in the southwest of France. This was a follow-up of the initial campaign in 2005. CERES'07 consisted of two intensive observational periods (IOPs), of which one in spring and the other one in summer. During both IOPs, ground stations, tall towers, radiosondes and a number of aircrafts were used, including our own environmental research aircraft (ERA). The ERA is a small aircraft flying at low altitudes and low air speeds, equipped to measure fluxes of carbon dioxide, latent heat and sensible heat using the eddy-correlation technique. In addition, instruments are on board for measuring ground temperature, net radiation and photosynthetically active radiation (PAR). Flux data obtained with the ERA during CERES'07 have been analyzed and will be presented here. In the data analysis, we present regional fluxes of carbon dioxide focussing at seasonal trends in relation to landscape elements. To achieve this, flight tracks were split into homogeneous segments based on land cover, topography and soil type. During both IOPs, weather conditions were constant. This gives us the possibility to average data in each segment across all flights, though the issue of diurnal variation in surface fluxes and radiation still remains. In short, the analysis strategy on our airborne flux data from CERES'07 will be addressed in this presentation together with its results focussing at drivers for these fluxes at landscape scale.

Vellinga, O. S.; Hutjes, R. W. A.; Elbers, J. A.

2009-04-01

48

Total aerosol effect: radiative forcing or radiative flux perturbation?  

NASA Astrophysics Data System (ADS)

Uncertainties in aerosol radiative forcings, especially those associated with clouds, contribute to a large extent to uncertainties in the total anthropogenic forcing. The interaction of aerosols with clouds and radiation introduces feedbacks which can affect the rate of rain formation. In former assessments of aerosol radiative forcings, these effects have not been quantified. Also, with global aerosol-climate models simulating interactively aerosols and cloud microphysical properties, a quantification of the aerosol forcings in the traditional way is difficult to properly define. Here we argue that fast feedbacks should be included because they act quickly compared with the time scale of global warming. We show that for different forcing agents (aerosols and greenhouse gases) the radiative forcings as traditionally defined agree rather well with estimates from a method, here referred to as radiative flux perturbations (RFP), that takes these fast feedbacks and interactions into account. Based on our results, we recommend RFP as a valid option to compare different forcing agents, and to compare the effects of particular forcing agents in different models.

Lohmann, Ulrike; Rotstayn, Leon; Storelvmo, Trude; Jones, Andy; Menon, Surabi; Quaas, Johannes; Ekman, Annica; Koch, Dorothy; Ruedy, Reto

2010-05-01

49

Estimation of TOA radiative fluxes from the GERB instrument data  

NASA Astrophysics Data System (ADS)

The first Meteosat Second Generation (MSG) satellite was launched in August 2002. This EUMETSAT satellite carries 2 new instruments on the geostationary orbit: the Spinning Enhanced Visible and InfraRed Imager, SEVIRI, and the Geostationary Earth Radiation Budget, GERB. The unique feature of GERB in comparison with previous measurement missions of the Earth's radiation budget (e.g. ERBE, ScaRab and CERES experiments) is the high temporal sampling afforded by the geostationary orbit, albeit for a limited region of the globe. The GERB instrument provides accurate broadband measurements of the radiant energy originating in the reflection of the incoming solar energy by the Earth-atmosphere system and in the thermal emission within this system. The synergetic use of the SEVIRI data is needed to convert these directional measurements (radiances) into radiative fluxes at the top-of-atmosphere. Additionally, the SEVIRI data allows the enhancement of the spatial resolution of the GERB measurement. This paper describes the near real-time GERB processing system that has been set up at the Royal Meteorological Institute of Belgium (RMIB). This includes the unfiltering of the instrument data, the radiance-to-flux conversions and the enhancement of the instrument spatial resolution. An early validation of the instrument data by comparison with CERES data is presented. Finally, the different data formats, the way to access them and their expected accuracy are presented.

Clerbaux, Nicolas; Bertrand, Cedric; Dewitte, Steven; Gonzalez, Luis; Ipe, Alessandro; Nicula, Bogdan

2003-12-01

50

Modeling shortwave radiative fluxes from satellites  

NASA Astrophysics Data System (ADS)

During the last two decades, significant progress has been made in assessing the Earth Radiation Balance from satellite observations. Yet, satellite based estimates differ from each other and from those provided by numerical models. Major issues are related to quality of satellite observations, such as the frequent changes in satellite observing systems, degradation of sensors, restricted spectral intervals and viewing geometry of sensors, and changes in the quality of atmospheric inputs that drive the inference schemes. To reduce differences among the satellite based estimates requires, among others, updates to inference schemes so that most recent auxiliary information can be fully utilized. This paper reports on improvements introduced to a methodology developed at the University of Maryland to estimate shortwave (SW) radiative fluxes within the atmosphere system from satellite observations, the implementation of the approach with newly available auxiliary information, evaluation of the downwelling SW flux against ground observations, and comparison with independent satellite methods and numerical models. Specifically, introduced are: new Narrow to Broadband (N/B) transformations and new Angular Distribution Models (ADM) for clear and cloudy sky that incorporate most recent land use classifications; improved aerosol treatment; separation of clouds by phase; improved sun-earth geometry; and implementation at 0.5° spatial resolution at 3-hourly intervals integrated to daily and monthly time scales. When compared to an earlier version of the model as implemented at 2.5° at global scale and against observations from the globally distributed Baseline Surface Radiation Network (BSRN) stations for a period of six years (at monthly time scale), the bias was reduced from 8.6 (4.6%) to -0.5 (0.3%) W/m2, the standard deviation from 16.6 (8.9%) to 14.5 (7.8%) W/m2while the correlation remained high at 0.98 in both cases. Evaluation was also done over oceanic sites as available from the Pilot Research Moored Array in the Tropical Atlantic (PIRATA) moorings and from the Tropical Atmosphere Ocean/Triangle Trans-Ocean Buoy Network (TAO/TRITON) moorings in the tropical Pacific Ocean. Overall, results over oceans were not as good as over land for all the satellite retrievals compared in this study.

Ma, Y.; Pinker, R. T.

2012-12-01

51

Atmospheric neutrino flux measurement using upgoing muons  

Microsoft Academic Search

We report on the first measurement of the flux of upgoing muons resulting from interactions of atmospheric neutrinos in the rock below MACRO. The ratio of the observed to the expected number of events integrated over all nadir angles is 0.73 ± .09stat. ± .06sys. ± .12theor.. The flux of upgoing muons as a function of nadir angle is presented

S. Ahlen; M. Ambrosio; R. Antolini; G. Auriemma; R. Baker; A. Baldini; G. C. Barbarino; B. C. Barish; G. Battistoni; R. Bellotti; C. Bemporad; P. Bernardini; H. Bilokon; V. Bisi; C. Bloise; C. Bower; S. Bussino; F. Cafagna; M. Calicchio; D. Campana; M. Carboni; M. Castellano; S. Cecchini; F. Cei; P. Celio; V. Chiarella; R. Cormack; A. Corona; S. Coutu; G. De Cataldo; H. Dekhissi; C. De Marzo; E. Diehl; I. De Mitri; M. De Vincenzi; A. Di Credico; O. Erriquez; C. Favuzzi; C. Forti; P. Fusco; G. Giacomelli; G. Giannini; N. Giglietto; M. Grassi; P. Green; A. Grillo; F. Guarino; P. Guarnaccia; C. Gustavino; A. Habig; K. Hanson; A. Hawthorne; R. Heinz; J. T. Hong; E. Iarocci; E. Katsavounidis; E. Kearns; S. Kyriazopoulou; E. Lamanna; D. S. Levin; P. Lipari; G. Liu; R. Liu; N. P. Longley; M. J. Longo; Y. Lu; G. Ludlam; G. Mancarella; G. Mandrioli; A. Margiotta-Neri; A. Marin; A. Marini; D. Martello; A. Marzari-Chiesa; M. N. Mazziotta; D. G. Michael; S. Mikheyev; L. Miller; M. Mittelbrunn; P. Monacelli; T. Montaruli; M. Monteno; S. Mufson; J. Musser; D. Nicoló; R. Nolty; S. Nutter; C. Okada; C. Orth; G. Osteria; O. Palamara; S. Parlati; V. Patera; L. Patrizii; R. Pazzi; C. W. Peck; J. Petrakis; S. Petrera; N. D. Pignatano; P. Pistilli; V. Popa; A. Rainó; J. Reynoldson; F. Ronga; A. Sanzgiri; F. Sartogo; C. Satriano; L. Satta; E. Scapparone; K. Scholberg; A. Sciubba; P. Serra-Lugaresi; M. Severi; M. Sitta; P. Spinelli; M. Spinetti; M. Spurio; R. Steinberg; J. L. Stone; L. R. Sulak; A. Surdo; G. Tarlé; V. Togo; V. Valente; C. W. Walter; R. Webb; W. Worstell

1995-01-01

52

The Atmospheric Radiation Measurement Program  

SciTech Connect

In 1990, the treatment of clouds in climate models was identified as the highest-priority research topic in the newly formed United States Global Change Research Program. ARM was created to meet this challenge. The goal of the ARM program is to increase our understanding of the interaction between clouds and atmospheric radiative fluxes, and then to capture that knowledge in improved climate models. From an observational perspective, the focus is on measuring the solar and thermal infrared radiative fluxes at Earth's surface, and all of the atmospheric quantities that affect those fluxes. In this article, we describe the ARM central facility in the Southern Great Plains and the advanced instrumentation found there and also compare the site to an astronomical observatory. We provide examples of ARM science progress in radiative transfer studies, cloud property retrievals, and cloud modeling and parameterization. The ARM observatory has become an integral component of international collaborations and of US government research programs sponsored by agencies such as NASA and the National Oceanic and Atmospheric Administration. Although the Southern Great Plains site remains our premier facility, data from the remote ARM sites in Alaska and the Pacific are widely used to study polar and tropical climates. Along with continued observation at the existing ARM facilities, we also hope to build a mobile facility that would extend our measurement capability to any location on earth for a period of months to a year.

Ackerman, Thomas P.; Stokes, Gerald M.

2003-01-01

53

Heat flux microsensor measurements and calibrations  

NASA Astrophysics Data System (ADS)

A new thin-film heat flux gage has been fabricated specifically for severe high temperature operation using platinum and platinum-10 percent rhodium for the thermocouple elements. Radiation calibrations of this gage were performed at the AEDC facility over the available heat flux range (approx. 1.0 - 1,000 W/cu cm). The gage output was linear with heat flux with a slight increase in sensitivity with increasing surface temperature. Survivability of gages was demonstrated in quench tests from 500 C into liquid nitrogen. Successful operation of gages to surface temperatures of 750 C has been achieved. No additional cooling of the gages is required because the gages are always at the same temperature as the substrate material. A video of oxyacetylene flame tests with real-time heat flux and temperature output is available.

Terrell, James P.; Hager, Jon M.; Onishi, Shinzo; Diller, Thomas E.

1992-09-01

54

Radiation measurements aboard Spacelab 1.  

PubMed

The radiation environment inside Spacelab 1 was measured by a set of passive radiation detectors distributed throughout the volume inside the module, in the access tunnel, and outside on the pallet. Measurements of the low-LET (linear energy transfer) component obtained from the thermoluminescence detectors ranged from 102 to 190 millirads, yielding an average low-LET dose rate of 11.2 millirads per day inside the module, about twice the low-LET dose rate measured on previous flights of the space shuttle. Because of the higher inclination of the orbit (57 degrees versus 28.5 degrees for previous shuttle flights), substantial fluxes of highly ionizing HZE particles (high charge and energy galactic cosmic rays were observed, yielding an overall average mission dose-equivalent of about 150 millirems, more than three times higher than measured on previous shuttle missions. PMID:11540798

Benton, E V; Almasi, J; Cassou, R; Frank, A; Henke, R P; Rowe, V; Parnell, T A; Schopper, E

1984-07-13

55

Eddy Correlation Flux Measurement System (ECOR) Handbook  

SciTech Connect

The eddy correlation (ECOR) flux measurement system provides in situ, half-hour measurements of the surface turbulent fluxes of momentum, sensible heat, latent heat, and carbon dioxide (CO2) (and methane at one Southern Great Plains extended facility (SGP EF) and the North Slope of Alaska Central Facility (NSA CF). The fluxes are obtained with the eddy covariance technique, which involves correlation of the vertical wind component with the horizontal wind component, the air temperature, the water vapor density, and the CO2 concentration.

Cook, DR

2011-01-31

56

Measurement of Circumsolar Radiation.  

National Technical Information Service (NTIS)

An instrument system has been developed to measure the flux of energy from the sun and the circumsolar region (the small-angle region around the sun) as a function of angle, wavelength, and atmospheric conditions. The measurements are necessary to accurat...

D. Grether J. Nelson M. Wahlig

1975-01-01

57

Advances in the Surface Renewal Flux Measurement Method  

NASA Astrophysics Data System (ADS)

The measurement of ecosystem-scale energy and mass fluxes between the planetary surface and the atmosphere is crucial for understanding geophysical processes. Surface renewal is a flux measurement technique based on analyzing the turbulent coherent structures that interact with the surface. It is a less expensive technique because it does not require fast-response velocity measurements, but only a fast-response scalar measurement. It is therefore also a useful tool for the study of the global cycling of trace gases. Currently, surface renewal requires calibration against another flux measurement technique, such as eddy covariance, to account for the linear bias of its measurements. We present two advances in the surface renewal theory and methodology that bring the technique closer to becoming a fully independent flux measurement method. The first advance develops the theory of turbulent coherent structure transport associated with the different scales of coherent structures. A novel method was developed for identifying the scalar change rate within structures at different scales. Our results suggest that for canopies less than one meter in height, the second smallest coherent structure scale dominates the energy and mass flux process. Using the method for resolving the scalar exchange rate of the second smallest coherent structure scale, calibration is unnecessary for surface renewal measurements over short canopies. This study forms the foundation for analysis over more complex surfaces. The second advance is a sensor frequency response correction for measuring the sensible heat flux via surface renewal. Inexpensive fine-wire thermocouples are frequently used to record high frequency temperature data in the surface renewal technique. The sensible heat flux is used in conjunction with net radiation and ground heat flux measurements to determine the latent heat flux as the energy balance residual. The robust thermocouples commonly used in field experiments underestimate the sensible heat flux, yielding results that are less than 50% of the sensible heat flux measured with finer sensors. We present the methodology for correcting the thermocouple signal to avoid underestimating the heat flux at both the smallest and the second smallest coherent structure scale.

Shapland, T. M.; McElrone, A.; Paw U, K. T.; Snyder, R. L.

2011-12-01

58

Particle flux measurements with pump limiters  

SciTech Connect

The pressure buildup in pump limiters is a function of the incident particle flux, the pump limiter geometry, particle-surface interactions, and, under certain conditions, nonlinear effects due to interactions of the neutral gas with the incoming plasma. At sufficiently low density and for short pump limiter throat, the pressure observed in the pump limiter chamber is a direct measure of the particle flux at the limiter slot. This paper discusses a simple model for the correlation between particle flux and pump limiter pressure. In addition, some estimates are presented on the thermalization of fast neutrals in the pump limiter duct and its implications for ''enhanced particle collection.''

Mioduszewski, P.

1986-01-01

59

METHOD FOR MEASURING RADIATION  

DOEpatents

A method for measuring an unknown integrated quantity of radiation with a condenser ionization chamber is described. The chamber is initially charged to a predetermined voltage by a voltage source. The chamber is then removed from the source and exposed to an unknown quantity of radiation for a period of time. The quantity of radiation to which the chamber was exposed is then measured by detecting the magnitude of the pulse of current necessary to recharge the chamber of its initial value through a suitable impedance. The current pulse is amplified and measured directly by a suitable pulse height analyzing system. (AEC)

Roesch, W.C.; McCall, R.C.

1961-11-21

60

Seasonal and Diurnal Fluxes of Radiation, Heat, Water Vapor, and Carbon Dioxide over a Suburban Area  

Microsoft Academic Search

Based on 1 yr of field measurements, the diurnal, seasonal, and annual fluxes of energy and carbon dioxide (CO2) at a residential area of Tokyo, Japan, are described. The major findings are as follows. 1) The storage heat flux G in the daytime had little seasonal variation, irrespective of significant seasonal change of net all-wave radiation Rn. 2) The latent

R. Moriwaki; M. Kanda

2004-01-01

61

International Photolysis Frequency Measurement and Model Intercomparison (IPMMI): Spectral actinic solar flux measurements and modeling  

Microsoft Academic Search

The International Photolysis Frequency Measurement and Model Intercomparison (IPMMI) took place in Boulder, Colorado, from 15 to 19 June 1998, aiming to investigate the level of accuracy of photolysis frequency and spectral downwelling actinic flux measurements and to explore the ability of radiative transfer models to reproduce the measurements. During this period, 2 days were selected to compare model calculations

A. F. Bais; S. Madronich; J. Crawford; S. R. Hall; B. Mayer; M. van Weele; J. Lenoble; J. G. Calvert; C. A. Cantrell; R. E. Shetter; A. Hofzumahaus; P. Koepke; P. S. Monks; G. Frost; R. McKenzie; N. Krotkov; A. Kylling; W. H. Swartz; S. Lloyd; G. Pfister; T. J. Martin; E.-P. Roeth; E. Griffioen; A. Ruggaber; M. Krol; A. Kraus; G. D. Edwards; M. Mueller; B. L. Lefer; P. Johnston; H. Schwander; D. Flittner; B. G. Gardiner; J. Barrick; R. Schmitt

2003-01-01

62

Evapotranspiration fluxes over mixed vegetation areas measured from large aperture scintillometer  

Microsoft Academic Search

Routine measurement of spatially averaged surface fluxes of sensible heat (H) in river basins is now feasible. These fluxes, when combined with net radiation estimates, can be used to derive areally averaged actual evapotranspiration (ET). The scintillation method is shown to be promising method for estimating areally averaged sensible heat fluxes. The large aperture scintillometer (LAS) is an optical device

H. M. Hemakumara; Lalith Chandrapala; Arnold F. Moene

2003-01-01

63

Experimental Flux Measurements on a Network Scale  

PubMed Central

Metabolic flux is a fundamental property of living organisms. In recent years, methods for measuring metabolic flux in plants on a network scale have evolved further. One major challenge in studying flux in plants is the complexity of the plant’s metabolism. In particular, in the presence of parallel pathways in multiple cellular compartments, the core of plant central metabolism constitutes a complex network. Hence, a common problem with the reliability of the contemporary results of 13C-Metabolic Flux Analysis in plants is the substantial reduction in complexity that must be included in the simulated networks; this omission partly is due to limitations in computational simulations. Here, I discuss recent emerging strategies that will better address these shortcomings.

Schwender, Jorg

2011-01-01

64

Horizontal Radiative Fluxes in Clouds at Absorbing Wavelengths.  

National Technical Information Service (NTIS)

We discuss the effect of horizontal fluxes on the accuracy of a conventional plane-parallel radiative transfer calculation for a single pixel, known as the Independent Pixel Approximation (IPA) at absorbing wavelengths. Vertically integrated horizontal fl...

A. Marshak L. Oreopoulos A. B. Davis W. J. Wiscombe

1998-01-01

65

Dual neutron flux/temperature measurement sensor  

DOEpatents

Simultaneous measurement of neutron flux and temperature is provided by a single sensor which includes a phosphor mixture having two principal constituents. The first constituent is a neutron sensitive 6LiF and the second is a rare-earth activated Y203 thermophosphor. The mixture is coated on the end of a fiber optic, while the opposite end of the fiber optic is coupled to a light detector. The detected light scintillations are quantified for neutron flux determination, and the decay is measured for temperature determination. 3 figs.

Mihalczo, J.T.; Simpson, M.L.; McElhaney, S.A.

1994-10-04

66

ATMOSPHERIC RADIATION MEASUREMENT PROGRAM  

EPA Science Inventory

The Atmospheric Radiation Measurement Program (ARM) is the largest global change research program supported by the U.S. Department of Energy (DOE). ARM scientists focus on obtaining field measurements and developing models to better understand the processes that control solar and...

67

Fast Neutron Flux Measurement through Neutron Activation  

Microsoft Academic Search

Neutron activation of various materials is often used to detect the fluence from a neutron source. In this report silver sleeves were placed around individual Geiger-Mueller tubes, and set in a polyethylene box to measure the neutron flux from a D-D fusion pinch. The silver is neutron activated from the DPF neutrons which are moderated by the polyethylene box, and

Jim Ferguson

2002-01-01

68

Plasma momentum meter for momentum flux measurements  

DOEpatents

Invention comprises an instrument in which momentum flux onto a biasable target plate is transferred via a suspended quartz tube onto a sensitive force transducer--a capacitance-type pressure gauge. The transducer is protected from thermal damage, arcing and sputtering, and materials used in the target and pendulum are electrically insulating, rigid even at elevated temperatures, and have low thermal conductivity. The instrument enables measurement of small forces (10.sup.-5 to 10.sup.3 N) accompanied by high heat fluxes which are transmitted by energetic particles with 10's of eV of kinetic energy in a intense magnetic field and pulsed plasma environment.

Zonca, Fulvio (Rome, IT); Cohen, Samuel A. (Hopewell, NJ); Bennett, Timothy (Princeton, NJ); Timberlake, John R. (Allentown, NJ)

1993-01-01

69

Plasma momentum meter for momentum flux measurements  

DOEpatents

Invention comprises an instrument in which momentum flux onto a biasable target plate is transferred via a suspended quartz tube onto a sensitive force transducer - a capacitance-type pressure gauge. The transducer is protected from thermal damage, arcing and sputtering, and materials used in the target and pendulum are electrically insulating, rigid even at elevated temperatures, and have low thermal conductivity. The instrument enables measurement of small forces (10[sup [minus]5] to 10[sup 3] N) accompanied by high heat fluxes which are transmitted by energetic particles with 10's of eV of kinetic energy in an intense magnetic field and pulsed plasma environment.

Zonca, F.; Cohen, S.A.; Bennett, T.; Timberlake, J.R.

1991-01-01

70

Plasma momentum meter for momentum flux measurements  

DOEpatents

Invention comprises an instrument in which momentum flux onto a biasable target plate is transferred via a suspended quartz tube onto a sensitive force transducer - a capacitance-type pressure gauge. The transducer is protected from thermal damage, arcing and sputtering, and materials used in the target and pendulum are electrically insulating, rigid even at elevated temperatures, and have low thermal conductivity. The instrument enables measurement of small forces (10{sup {minus}5} to 10{sup 3} N) accompanied by high heat fluxes which are transmitted by energetic particles with 10`s of eV of kinetic energy in an intense magnetic field and pulsed plasma environment.

Zonca, F.; Cohen, S.A.; Bennett, T.; Timberlake, J.R.

1991-12-31

71

Plasma momentum meter for momentum flux measurements  

SciTech Connect

Invention comprises an instrument in which momentum flux onto a biasable target plate is transferred via a suspended quartz tube onto a sensitive force transducer--a capacitance-type pressure gauge. The transducer is protected from thermal damage, arcing and sputtering, and materials used in the target and pendulum are electrically insulating, rigid even at elevated temperatures, and have low thermal conductivity. The instrument enables measurement of small forces (10.sup.-5 to 10.sup.3 N) accompanied by high heat fluxes which are transmitted by energetic particles with 10's of eV of kinetic energy in a intense magnetic field and pulsed plasma environment.

Zonca, Fulvio (Rome, IT); Cohen, Samuel A. (Hopewell, NJ); Bennett, Timothy (Princeton, NJ); Timberlake, John R. (Allentown, NJ)

1993-01-01

72

Satellite beacon measurements of protonospheric fluxes  

NASA Astrophysics Data System (ADS)

The ionospheric and protonospheric regions of the plasmasphere, which are dominated by the O(+) and H(+) ionic species, respectively, interact by means of proton fluxes within tubes of magnetic force. The present study is concerned with the determination of these fluxes by the beacon satellite technique as used in the ATS-6 experiment in relation to three observing sites: Boulder, Colorado; Lancaster, U.K.; and Fairbanks, Alaska. From plasmasphere models based on solutions of the time dependent O(+) and H(+) momentum and continuity equations, it is shown that the time differential of the residual content as measured at Lancaster provides a good estimate of the protonospheric flux at 4000 km altitude in the L = 1.8 magnetic shell under quiet geomagnetic conditions. The effect of the neutral thermospheric wind on the protonospheric flux is also investigated. Fluxes determined by the beacon technique for the period from September 1975 to July 1976 are shown, and these are compared with typical results derived from other techniques.

Poulter, E. M.; Hargreaves, J. K.; Bailey, G. J.; Moffett, R. J.

1981-12-01

73

Near-Core and In-Core Neutron Radiation Monitors for Real Time Neutron Flux Monitoring and Reactor Power Level Measurements  

SciTech Connect

MPFDs are a new class of detectors that utilize properties from existing radiation detector designs. A majority of these characteristics come from fission chamber designs. These include radiation hardness, gamma-ray background insensitivity, and large signal output.

Douglas S. McGregor; Marvin L. Adams; Igor Carron; Paul Nelson

2006-06-12

74

Measuring UV radiation on inclined surfaces  

Microsoft Academic Search

In general measurements of UV-radiation are related to horizontal surfaces, as e.g. also done for the internationally standardized and applied UV-index. In order to get more information on biologically relevant UV-exposure, there is a need for quantitative data of radiation fluxes on tilted surfaces. UV exposure of the human skin is one of the most essential issues in UV research,

Andreas Oppenrieder; Peter Hoeppe; Peter Koepke; Jochen Reuder; Meinhard Seefeldner; Dieter Rabus

2003-01-01

75

Airborne measurements of mass, momentum, and energy fluxes for the boardman-arm regional flux experiment-1991. Preliminary data release. Technical memo  

SciTech Connect

During 2 - 19 June 1991 the Atmospheric Turbulence and Diffusion Division of NOAA measured flux densities of mass, momentum, and energy from an airplane in support of DOE's Atmospheric Radiation Measurement (ARM) program. Over 507 horizontal flux transects were completed, along with 24 vertical atmospheric profiles, during the 93 flight hours. Flux transects passed over both irrigated farmland and steppe. The report describes the variation in wind, radiation, and surface temperature, along with exchange of mass (CO2, H2O, and O3), momentum, and energy as observed along the transects. Airborne measurements are compared with those from flux towers in wheat, corn, and steppe. In general, the measurements correspond well. The largest difference occurs at the steppe tower, with stronger heat fluxes reported by the tower. This discrepancy increases as heat flux increases. The cause may be a significant vertical flux divergence or an inconsistant specification of the mean state.

Crawford, T.L.; Dobosy, R.J.; Birdwell, K.R.

1993-04-01

76

Angular Distribution Models for Top-of-Atmosphere Radiative Flux Estimation from the Clouds and the Earth's Radiant Energy System Instrument on the Tropical Rainfall Measuring Mission Satellite. Part I: Methodology  

Microsoft Academic Search

Clouds and the Earth's Radiant Energy System (CERES) investigates the critical role that clouds and aerosols play in modulating the radiative energy flow within the Earth-atmosphere system. CERES builds upon the foundation laid by previous missions, such as the Earth Radiation Budget Experiment, to provide highly accurate top-of-atmosphere (TOA) radiative fluxes together with coincident cloud and aerosol properties inferred from

Norman G. Loeb; Natividad Manalo-Smith; Seiji Kato; Walter F. Miller; Shashi K. Gupta; Patrick Minnis; Bruce A. Wielicki

2003-01-01

77

A note on vector flux models for radiation dose calculations.  

PubMed

This paper reviews and extends modelling of anisotropic fluxes for radiation belt protons to provide closed-form equations for vector proton fluxes and proton flux anisotropy in terms of standard omnidirectional flux models. These equations provide a flexible alternative to the data-based vector flux models currently available. At higher energies, anisotropy of trapped proton flux in the upper atmosphere depends strongly on the variation of atmospheric density with altitude. Calculations of proton flux anisotropies using present models require specification of the average atmospheric density along trapped particle trajectories and its variation with mirror point altitude. For an isothermal atmosphere, calculations show that in a dipole magnetic field, the scale height of this trajectory-averaged density closely approximates the scale height of the atmosphere at the mirror point of the trapped particle. However, for the earth's magnetic field, the altitudes of mirror points vary for protons drifting in longitude. This results in a small increase in longitude-averaged scale heights compared to the atmospheric scale heights at minimum mirror point altitudes. The trajectory-averaged scale heights are increased by about 10-20% over scale heights from standard atmosphere models for protons mirroring at altitudes less than 500 km in the South Atlantic Anomaly. Atmospheric losses of protons in the geomagnetic field minimum in the South Atlantic Anomaly control proton flux anisotropies of interest for radiation studies in low earth orbit. Standard atmosphere models provide corrections for diurnal, seasonal and solar activity-driven variations. Thus, determination of an "equilibrium" model of trapped proton fluxes of a given energy requires using a scale height that is time-averaged over the lifetime of the protons. The trajectory-averaged atmospheric densities calculated here lead to estimates for trapped proton lifetimes. These lifetimes provide appropriate time-averaging intervals for equilibrium models of trapped proton fluxes. PMID:11538012

Kern, J W

1994-01-01

78

Novel Instrumentation for Methane Flux Measurements  

NASA Astrophysics Data System (ADS)

We describe the development and testing of a new compact, rugged and inexpensive instrument for measurements of methane flux in ambient air. The instrument is based on a new technology called Off-Axis Integrated Cavity Output Spectroscopy (Off-Axis ICOS). This novel instrument measures methane with high sensitivity, accuracy (<2 ppbv at 1 Hz), and specificity in real time (no cross interferences). The instrument combines inexpensive, robust telecommunications-grade room-temperature diode laser operating at 1.65 microns with Off-Axis ICOS to yield an instrument capable of continuously recording data in the field with high precision (better than 0.2% uncertainty at a 10-Hz rate). We will discuss the measurement strategy in detail and present recent results demonstrating real-time measurements without the need for any user intervention. Ongoing efforts to demonstrate the instrument's capabilities to record measurements with high precision and accuracy without calibration over extended periods as well as testing of the instrument at field sites in the AmeriFlux and FLUXNET networks, and NOAA/CMDL will also be discussed. By significantly increasing the accuracy and precision of methane flux measurements, the Off-Axis ICOS instrument will enhance local, regional and global studies of global warming and facilitate controlled multi-year studies and comparisons between field sites. These studies, which could involve using the instruments aboard airplanes to enable coverage over large distances and to correlate with satellite images, will help track and quantify the global carbon cycle on small and large spatial scales, and enable atmospheric chemists to generate more reliable models of climate change and determine environmental impact.

Owano, T.; Baer, D.; Gupta, M.; Ricci, K.; O'Keefe, A.

2004-12-01

79

Amplification of scattered induced radiation flux in high-gain laser rods  

NASA Astrophysics Data System (ADS)

The spatial distribution of induced radiation flkux within a laser rod is determined through integrated investigations of the angular characteristics of the noisy induced radiation exiting the rod and the angular characteristics of the radiation scattering on its lateral surface. The measurements are made on neodymium activated yttrium aluminum garnet active elements in the form of a rod with a cylindrical surface and plane parallel polished ends. Antireflection coatings were applied to the ends of the elements to reduce reflection to approximately 0.1%. It is demonstrated that closed induced radiant fluxes for which lasing conditions are satisfied can form during strong scattering on the boundaries of the active medium. The stability of these fluxes depends strongly upon their orientation. The most stable fluxes are found to be those which scattered repeatedly at other than mirror angles. The occurrence of a halo of the induced radiation accompanying the occurrence of the generated mode is noted.

Skorobogatov, B. S.; Usoskin, A. I.

1985-04-01

80

Evaluation of Arctic Broadband Surface Radiation Measurements  

SciTech Connect

The Arctic is a challenging environment for making in-situ radiation measurements. A standard suite of radiation sensors is typically designed to measure the total, direct and diffuse components of incoming and outgoing broadband shortwave (SW) and broadband thermal infrared, or longwave (LW) radiation. Enhancements can include various sensors for measuring irradiance in various narrower bandwidths. Many solar radiation/thermal infrared flux sensors utilize protective glass domes and some are mounted on complex mechanical platforms (solar trackers) that rotate sensors and shading devices that track the sun. High quality measurements require striking a balance between locating sensors in a pristine undisturbed location free of artificial blockage (such as buildings and towers) and providing accessibility to allow operators to clean and maintain the instruments. Three significant sources of erroneous data include solar tracker malfunctions, rime/frost/snow deposition on the instruments and operational problems due to limited operator access in extreme weather conditions. In this study, a comparison is made between the global and component sum (direct [vertical component] + diffuse) shortwave measurements. The difference between these two quantities (that theoretically should be zero) is used to illustrate the magnitude and seasonality of radiation flux measurement problems. The problem of rime/frost/snow deposition is investigated in more detail for one case study utilizing both shortwave and longwave measurements. Solutions to these operational problems are proposed that utilize measurement redundancy, more sophisticated heating and ventilation strategies and a more systematic program of operational support and subsequent data quality protocols.

Matsui, N.; Long, Charles N.; Augustine, J. A.; Halliwell, D.; Uttal, Taneil; Longenecker, D.; Niebergale, J.; Wendell, J.; Albee, R.

2012-02-24

81

Indication of increasing solar ultraviolet-B radiation flux in alpine regions  

Microsoft Academic Search

Measurements at the Jungfraujoch High Mountain Station (Swiss Alps, 47°N, 3,576 meters above sea level) indicate that there has been a slight increase of about 1% per year in the flux of solar ultraviolet-B radiation (290 to 330 nanometers) since 1981. A Robertson-Berger detector was used to measure solar erythemal radiation. The increase can be related to a long-term ozone

M. Blumthaler; W. Ambach

1990-01-01

82

Hawking Radiation and Hawking Flux from Spherical Reduction  

NASA Astrophysics Data System (ADS)

In view of the recent progress in 2D quantum gravity [1] from spherical reduction of Einstein gravity (SRG) it should be possible to also derive the correct radiative flux to infinity related to the Hawking temperature at the horizon [2] from the SRG action in D = 2. For minimally coupled scalars the correct result had been obtained a long time ago [3]. As shown first in [4] a calculation based only upon the conformal anomaly in the presence of dilaton fields leads to an unacceptable (negative) flux at infinity, requiring the addition of a nonconformally invariant piece to the effective action. A more recent calculation [5] of that anomaly disagreed with [4] and further conflicting results appeared in the literature [6, 7, 8, 9]. We (together with H. Liebl) have derived that anomaly for completely general nonminimal interaction of the scalar fields in D = 2 and for general dilaton dependent measure [8] and used the integration of the standard energy momentum conservation with Unruh vacuum at the horizon [2] to arrive at the same result for the flux as [4]. Our computation of the anomaly agreed with [6, 9, 10] in the case of SRG. After paper [11] our computation of the anomaly now is generally accepted (cf. e.g. [12]) Using the proper "extended" energy momentum conservation in the presence of dilaton interaction for matter and calculating the corresponding "dilaton anomaly" we were able to show [13] that the correct positive flux at infinity follows, completing earlier attempts in this direction [14]. Our computation was based upon a novel application of the heat kernel technique [15]. As a by-product, but not to be used in our argument, we also gave for the first time the full effective action in the presence of a dilaton field which couples arbitrarily to the scalar field and which enters in a general way in the quantum measure. This action extends the one for minimal coupling [16] to the most general case of a dilaton interaction in D = 2. Possible criticisms of our result [17, 18, 19] are discussed.

Kummer, W.; Vassilevich, D. V.

2002-12-01

83

A mobile detector for measurements of the atmospheric muon flux  

NASA Astrophysics Data System (ADS)

Measurements of the underground atmospheric muon flux are important in order to determine accurately the overburden in mwe (meter water equivalent) of an underground laboratory for appreciating which kind of experiments are feasible for that location. Slanic- Prohava is one of the 7 possible locations for the European large underground experiment LAGUNA (Large Apparatus studying Grand Unification and Neutrino Astrophysics). A mobile device consisting of 2 scintillator plates (?0.9 m2, each) one above the other and measuring in coincidence, was set-up for determining the muon flux. The detector it is installed on a van which facilitates measurements on different positions at the surface or in the underground and it is in operation since autumn 2009. The measurements of muon fluxes presented in this contribution have been performed in the underground salt mine Slanic-Prahova, Romania, where IFIN-HH has built a low radiation level laboratory, and at the surface on different sites of Romania, at different elevations from 0 m a.s.l up to 655 m a.s.l. Based on our measurements we can say that Slanic site is a feasible location for LAGUNA in Unirea salt mine at a water equivalent depth of 600 mwe. The results have been compared with Monte-Carlo simulations performed with the simulation codes CORSIKA and MUSIC.

Mitrica, B.; Brancus, I. M.; Margineanu, R.; Petcu, M.; Dima, M.; Sima, O.; Haungs, A.; Rebel, H.; Petre, M.; Toma, G.; Saftoiu, A.; Apostu, A.

2011-04-01

84

Precision absolute measurements of the radiation flux from the discrete sources Taurus-A and Cassiopeia-A and of the atmospheric absorption of radio waves at ?=5.28 cm  

Microsoft Academic Search

Results are given of absolute measuremenes of the ~adio flux from the discrete sources Taurus-A and Cassiopeia-A at a wavelength of k = 5,28 era. A precision method based on a comparison with the thermal radiation from an absolutely black disk placed in the Frauahofer region of the antenna was used. The fluxes were (6.46  0.3) X X 10

D. A. Dmitrenko; K. M. Strezhneva

1967-01-01

85

The CERES/ARM/GEWEX experiment (CAGEX) for the retrieval of radiative fluxes with satellite data  

SciTech Connect

Results from a temporally intensive, limited area, radiative transfer model experiment are on-line for investigating the vertical profile of shortwave and longwave radiative fluxes from the surface to the top of the atmosphere (TOA). The CERES/ARM/GEWEX Experiment (CAGEX) Version 1 provides a record of fluxes that have been computed with a radiative transfer code; the atmospheric sounding, aerosol, and satellite-retrieved cloud data on which the computations have been based; and surface-based measurements of radiative fluxes and cloud properties from ARM for comparison. The computed broadband fluxes at TOA show considerable scatter when compared with fluxes that are inferred empirically from narrowband operational satellite data. At the surface, LW fluxes computed with an alternate sounding dataset compare well with pyrgeometer measurements. In agreement with earlier work, the authors find that the calculated SW surface insolation is larger than the measurements for clear-sky and total-sky conditions. This experiment has been developed to test retrievals of radiative fluxes and the associated forcings by clouds, aerosols, surface properties, and water vapor. Collaboration is sought; the goal is to extend the domain of meteorological conditions for which such retrievals can be done accurately. CAGEX Version 1 covers April 1994. Subsequent versions will (a) at first span the same limited geographical area with data from October 1995, (b) then expand to cover a significant fraction of the GEWEX Continental-Scale International Project region for April 1996 through September 1996, and (c) eventually be used in a more advanced form to validate CERES.

Charlock, T.P. [NASA/Langley Research Center, Hampton, VA (United States); Alberta, T.L. [Analytical Services and Materials, Inc., Hampton, VA (United States)

1996-11-01

86

ERRORS IN SOIL HEAT FLUX MEASUREMENT: EFFECTS OF FLUX PLATE DESIGN AND VARYING SOIL THERMAL PROPERTIES  

Technology Transfer Automated Retrieval System (TEKTRAN)

The flux plate method is the most commonly employed method for measuring soil heat flux (G) in surface energy balance studies. Nonetheless, significant errors in G measured with flux plates can occur unless proper installation techniques are used and necessary corrections made. The objective of th...

87

Measurements of Dephasing in Superconducting Flux Qubits  

NASA Astrophysics Data System (ADS)

The time over which a superposition of qubit states maintains phase coherence is an important figure of merit for a qubit. One technique for measuring this dephasing time is the Ramsey fringe, consisting of two ?/2 pulses detuned from resonance. Varying the time between the pulses produces a damped oscillatory fringe, with the frequency equal to the detuning from resonance and the decay time given by the dephasing time. The dephasing time can also be extracted from measurements of the spectroscopic linewidths for different excitation amplitudes. We report measurements using both techniques in a superconducting flux qubit, giving dephasing times of the order of 10 ns. We present the variation of the dephasing time with various parameters, such as qubit level splitting, readout SQUID operating point, and temperature. We compare our results with expected levels of low frequency noise in the qubit environment and discuss possible methods for enhancing the coherence, including spin echo pulse sequences.

Wu, C.-E.

2005-03-01

88

Multi-spectra Cosmic Ray Flux Measurement  

NASA Astrophysics Data System (ADS)

The Earth's upper atmosphere is constantly bombarded by rain of charged particles known as primary cosmic rays. These primary cosmic rays will collide with the atmospheric molecules and create extensive secondary particles which shower downward to the surface of the Earth. In recent years, a few studies have been done regarding to the applications of the cosmic ray measurements and the correlations between the Earth's climate conditions and the cosmic ray fluxes [1,2,3]. Most of the particles, which reach to the surface of the Earth, are muons together with a small percentage of electrons, gammas, neutrons, etc. At Georgia State University, multiple cosmic ray particle detectors have been constructed to measure the fluxes and energy distributions of the secondary cosmic ray particles. In this presentation, we will briefly describe these prototype detectors and show the preliminary test results. Reference: [1] K.Borozdin, G.Hogan, C.Morris, W.Priedhorsky, A.Saunders, L.Shultz, M.Teasdale, Nature, Vol.422, 277 (2003). [2] L.V. Egorova, V. Ya Vovk, O.A. Troshichev, Journal of Atmospheric and Terrestrial Physics 62, 955-966 (2000). [3] Henrik Svensmark, Phy. Rev. Lett. 81, 5027 (1998). )

He, Xiaochun; Dayananda, Mathes

2010-02-01

89

Measuring fast calcium fluxes in cardiomyocytes.  

PubMed

Cardiomyocytes have multiple Ca(2+) fluxes of varying duration that work together to optimize function (1,2). Changes in Ca(2+) activity in response to extracellular agents is predominantly regulated by the phospholipase C?- G?(q;) pathway localized on the plasma membrane which is stimulated by agents such as acetylcholine (3,4). We have recently found that plasma membrane protein domains called caveolae(5,6) can entrap activated G?(q;)(7). This entrapment has the effect of stabilizing the activated state of G?(q;) and resulting in prolonged Ca(2+) signals in cardiomyocytes and other cell types(8). We uncovered this surprising result by measuring dynamic calcium responses on a fast scale in living cardiomyocytes. Briefly, cells are loaded with a fluorescent Ca(2+) indicator. In our studies, we used Ca(2+) Green (Invitrogen, Inc.) which exhibits an increase in fluorescence emission intensity upon binding of calcium ions. The fluorescence intensity is then recorded for using a line-scan mode of a laser scanning confocal microscope. This method allows rapid acquisition of the time course of fluorescence intensity in pixels along a selected line, producing several hundreds of time traces on the microsecond time scale. These very fast traces are transferred into excel and then into Sigmaplot for analysis, and are compared to traces obtained for electronic noise, free dye, and other controls. To dissect Ca(2+) responses of different flux rates, we performed a histogram analysis that binned pixel intensities with time. Binning allows us to group over 500 traces of scans and visualize the compiled results spatially and temporally on a single plot. Thus, the slow Ca(2+) waves that are difficult to discern when the scans are overlaid due to different peak placement and noise, can be readily seen in the binned histograms. Very fast fluxes in the time scale of the measurement show a narrow distribution of intensities in the very short time bins whereas longer Ca(2+) waves show binned data with a broad distribution over longer time bins. These different time distributions allow us to dissect the timing of Ca(2+)fluxes in the cells, and to determine their impact on various cellular events. PMID:22143396

Golebiewska, Urszula; Scarlata, Suzanne

2011-11-29

90

Determination of Top-of-Atmosphere Longwave Radiative Fluxes: A Comparison Between Two Approaches Using ScaRaB Data.  

National Technical Information Service (NTIS)

Two conceptually different approaches (broadband-based ERBE and narrowband-based ISCCP approaches), used to derive the TOA longwave radiative fluxes, are compared using the ScaRaB simultaneous narrowband and broadband measurements. This study directly sho...

T. Chen W. B. Rossow

2001-01-01

91

Derivation of water vapor fluxes from Lidar measurements  

NASA Astrophysics Data System (ADS)

Two techniques are described by which the flux of water vapor can be derived from concentration measurements made by a Raman-Lidar. Monin-Obukhov similarity theory and dissipation techniques are used as the basis for these methods. The resulting fluxes are compared to fluxes from standard point instruments. The techniques described are appropriate for measuring the flux of any scalar quantity using Lidar measurements in the inner region of the boundary layer.

Eichinger, W. E.; Cooper, D. I.; Holtkamp, D. B.; Karl, R. R.; Quick, C. R.; Tiee, J. J.

1993-02-01

92

Radiation detection and measurement  

Microsoft Academic Search

Introductory material covers radiation sources, radiation interactions, general properties of radiation detectors, and counting statistics and error prediction. This is followed by detailed sections on gas-filled detectors, scintillation counters, semiconductor detectors, neutron detectors and spectroscopy, detector electronics and pulse processing, and miscellaneous radiation detectors and applications.

Glenn F. Knoll

1979-01-01

93

Radiative MHD simulation of an Emerging Flux Region  

NASA Astrophysics Data System (ADS)

We present a radiation magnetohydrodynamics (MHD) simulation of the birth of an active region. The simulation models the rise of a magnetic flux bundle from the convection zone into the solar photosphere. Observational properties of the simulation are consistent with recent, high-cadence and high spatial resolution observations of emerging flux regions taken by Hinode/SOT. Observational properties common to both simulation and observation include the hierarchical formation of progressively larger photospheric magnetic structures, the formation and disappearance of light bridges, umbral dots as well as penumbral filaments.

Cheung, C.; Rempel, M.; Title, A. M.; Schuessler, M.

2009-12-01

94

Plasma momentum meter for momentum flux measurements  

DOEpatents

An apparatus is described for measuring momentum flux from an intense plasma stream, comprising: refractory target means oriented normal to the flow of said plasma stream for bombardment by said plasma stream where said bombardment by said plasma stream applies a pressure to said target means, pendulum means for communicating a translational displacement of said target to a force transducer where said translational displacement of said target is transferred to said force transducer by an elongated member coupled to said target, where said member is suspended by a pendulum configuration means and where said force transducer is responsive to said translational displacement of said member, and force transducer means for outputting a signal representing pressure data corresponding to said displacement.

Zonca, F.; Cohen, S.A.; Bennett, T.; Timberlake, J.R.

1993-08-24

95

New radiosonde techniques to measure radiation profiles through the atmosphere  

NASA Astrophysics Data System (ADS)

Solar and thermal radiation fluxes are usually measured at Earth's surface and at the top of the atmosphere. Here we show radiosonde techniques that allow measuring radiation flux profiles and the radiation budget from the Earth's surface to above 30 km in the stratosphere. During two-hour flights solar shortwave and thermal longwave irradiance, downward and upward, is measured with four individual sensors at one-second resolution, along with standard PTU radiosonde profiles. Daytime and nighttime shortwave and longwave radiation measurements, and 24 hours surface measurements, allow determining radiation budget- and total net radiation profiles through the atmosphere. We use a double balloon technique to prevent pendulum motion during the ascent and to keep the sonde as horizontal as possible. New techniques using auto controlled airplanes are now investigated to retrieve the sonde after release at a certain altitude and to land it if possible at the launch station.

Kräuchi, Andreas; Philipona, Rolf; Romanens, Gonzague; Levrat, Gilbert

2013-04-01

96

Measurement of aerosol particles, gases and flux radiation in the Pico de Orizaba National Park, and its relationship to air pollution transport  

Microsoft Academic Search

Continuous atmospheric measurements were carried out at the Pico de Orizaba National Park (PONP), Mexico, in order to evaluate the characteristics and sources of air quality. This action allowed one to identify specific threats for the effective protection of natural resources and biodiversity. Results show the presence of particles and polluted gases transported by winds from the urban zones nearby

C. Márquez; T. Castro; A. Muhlia; M. Moya; A. Martínez-Arroyo; A. Báez

2005-01-01

97

PATHFINDER ATOMIC POWER PLANT DETAILED FLUX MEASUREMENTS IN SUPERHEATER CELLS  

Microsoft Academic Search

Experiments were conducted in the Allis-Chalmers Critical Experimental ; Facility to determine the regionaverage thermal flux and flux shape in a unit ; Pathfinder superheater cell. Accuiate values are necessary in order to calculate ; superheater constants. Measurements were made using Cu-Mn wires (radial traverse ; for regionaverage) and Al-U foils (sectioned for region-average) and foilettes ; (for flux detail).

H. F. Finn; R. H. Vollmer

1962-01-01

98

Measurement of Integrated Low Frequency Flux Noise in Superconducting Flux/Phase Qubits  

NASA Astrophysics Data System (ADS)

We measured the integrated low frequency flux noise (~1 m?0) of an rf SQUID as a flux qubit by fitting the resonant peaks from photon assistant tunneling (PAT). The energy relaxation time Tl between the ground and first excited states in the same potential well, measured directly in time domain, is 3 ns. From these results we identified low frequency flux noise as the dominant source of decoherence. In addition, we found that the measured values of integrated flux noise in three qubits of various sizes differ more than an order of magnitude.

Mao, Bo; Qiu, Wei; Han, Siyuan

2008-11-01

99

Upward mass fluxes in tropical upper troposphere and lower stratosphere derived from radiative transfer calculations  

NASA Astrophysics Data System (ADS)

Yang et al. [1] quantified vertical velocity and upward mass fluxes in tropical lower stratosphere based on radiative heating rate calculations using the Fu-Liou radiation model along with 8-year Southern Hemisphere Additional Ozonesondes balloon-borne measurements of temperature and ozone and cryogenic frost-point hygrometer measured water vapor. The impact of tropospheric clouds on stratospheric heating rates was considered using cloud distributions from the International Satellite Cloud Climatology Project. Since the radiative heating rate in the lower stratosphere can be as small as 0.1-0.2 K/day, an accurate radiative heating rate calculation including all radiatively active species is required. In this paper, we revisit the calculations in Yang et al. [1] by developing a line-by-line radiative transfer model (LBLRTM-D4S) for multiple scattering atmospheres. We consider the cloud impact using the cloud fields based on active lidar and radar observations from CALIPSO and CloudSat so that the quantification of upward mass fluxes in tropical lower stratosphere can be extended to tropical upper troposphere. The annual mean mass fluxes and vertical velocities from LBLRTM-D4S are ˜14 kg m-2 day-1 and 0.77 mm s-1, respectively, at 120 hPa (15.5 km), and ˜1.2 kg m-2 day-1 and 0.13 mm s-1 at 60 hPa (19.5 km). We examine the accuracy of three commonly used efficient radiation models including Fu-Liou, RRTM, and SBDART in estimating tropical upward mass fluxes against the LBLRTM-D4S results.

Lin, L.; Fu, Q.; Zhang, H.; Su, J.; Yang, Q.; Sun, Z.

2013-03-01

100

Flux Measurements of Trace Gases, Aerosols and Energy from the Urban Core of Mexico City  

NASA Astrophysics Data System (ADS)

As part of the MILAGRO field campaign in March 2006 we deployed a flux system in a busy district of Mexico City surrounded by congested avenues. The flux system consisted of a tall tower instrumented with fast-response sensors coupled with eddy covariance (EC) techniques to measure fluxes of volatile organic compounds (VOCs), CO2, CO, aerosols and energy. The measured fluxes represent direct measurements of emissions that include all major and minor emission sources from a typical residential and commercial district. In a previous study we demonstrated that the EC techniques are valuable tools to evaluate emissions inventories in urban areas, and understand better the atmospheric chemistry and the role that megacities play in global change. We measured fluxes of olefins using a Fast Olefin Sensor (FOS) and the EC technique, fluxes of aromatic and oxygenated VOCs by Proton Transfer Reaction-Mass Spectroscopy (PTR-MS) and the disjunct eddy covariance (DEC) technique, fluxes of CO2 and H2O with an open path Infrared Gas Analyzer (IRGA) and the EC technique, fluxes of CO using a modified gradient method and a commercial CO instrument, and fluxes of aerosols (organics, nitrates and sulfates) using an Aerodyne Aerosol Mass Spectrometer (AMS) and the EC technique. In addition we used a disjunct eddy accumulation (DEA) system to extend the number of VOCs. This system collected whole air samples as function of the direction of the vertical wind component, and the samples were analyzed on site using gas chromatography / flame ionization detection (GC-FID). We also measured fluxes of sensible and latent heat by EC and the radiation components with a net radiometer. Overall, these flux measurements confirm the results of our previous flux measurements in Mexico City in terms of the magnitude, composition, and distribution. We found that the urban surface is a net source of CO2 and VOCs. The diurnal patterns show clear anthropogenic signatures, with important contributions from vehicular traffic. The DEA results for individual hydrocarbons show that the alkane fluxes are considerably higher than alkene fluxes, which is consistent with ambient concentration measurements and with the emission inventory for Mexico City. CO fluxes, estimated from a modified gradient technique, were more than 10% of the measured CO2 fluxes (on a molar basis) which is much higher than is generally expected for combustion efficiencies in mobile and other sources. Investigation of this result is underway. The energy balance distribution and radiative parameters observed are similar to distributions and parameters reported for other urban sites.

Velasco, E.; Molina, L.; Lamb, B.; Pressley, S.; Grivicke, R.; Westberg, H.; Jobson, T.; Allwine, E.; Coons, T.; Jimenez, J.; Nemitz, E.; Alexander, L. M.; Worsnop, D.; Ramos, R.

2007-05-01

101

A comparison of new measurements of total monoterpene flux with improved measurements of speciated monoterpene flux  

NASA Astrophysics Data System (ADS)

Many monoterpenes have been identified in forest emissions using gas chromatography (GC). Until now, it has been impossible to determine whether all monoterpenes are appropriately measured using GC techniques. We used a proton transfer reaction mass spectrometer (PTR-MS) coupled with the eddy covariance (EC) technique to measure mixing ratios and fluxes of total monoterpenes above a ponderosa pine plantation. We compared PTR-MS-EC results with simultaneous measurements of eight speciated monoterpenes, ?-pinene, ?-pinene, 3-carene, d-limonene, ?-phellandrene, ?-terpinene, camphene, and terpinolene, made with an automated, in situ gas chromatograph with flame ionization detectors (GC-FID), coupled to a relaxed eddy accumulation system (REA). Monoterpene mixing ratios and fluxes measured by PTR-MS averaged 30±2.3% and 31±9.2% larger than by GC-FID, with larger mixing ratio discrepancies between the two techniques at night than during the day. Two unidentified peaks that correlated with ?-pinene were resolved in the chromatograms and completely accounted for the daytime difference and reduced the nighttime mixing ratio difference to 20±2.9%. Measurements of total monoterpenes by PTR-MS-EC indicated that GC-FID-REA measured the common, longer-lived monoterpenes well, but that additional terpenes were emitted from the ecosystem that represented an important contribution to the total mixing ratio above the forest at night.

Lee, A.; Schade, G. W.; Holzinger, R.; Goldstein, A. H.

2005-02-01

102

A comparison of new measurements of total monoterpene flux with improved measurements of speciated monoterpene flux  

NASA Astrophysics Data System (ADS)

Many monoterpenes have been identified in forest emissions using gas chromatography (GC). Until now, it has been impossible to determine whether all monoterpenes are appropriately measured using GC techniques. We used a proton transfer reaction mass spectrometer (PTR-MS) coupled with the eddy covariance (EC) technique to measure mixing ratios and fluxes of total monoterpenes above a ponderosa pine plantation. We compared PTR-MS-EC results with simultaneous measurements of eight speciated monoterpenes, ?-pinene, ?-pinene, 3-carene, d-limonene, ?-phellandrene, ?-terpinene, camphene, and terpinolene, made with an automated, in situ gas chromatograph with flame ionization detectors (GC-FID), coupled to a relaxed eddy accumulation system (REA). Monoterpene mixing ratios and fluxes measured by PTR-MS averaged 30±2.3% and 31±9.2% larger than by GC-FID, with larger differences at night than during the day. Four unidentified peaks that correlated with ?-pinene were resolved in the chromatograms and completely accounted for the daytime difference and reduced the nighttime difference to 19±3.4%. Measurements of total monoterpenes by PTR-MS-EC indicated that GC-FID-REA measured the common, longer-lived monoterpenes well, but that additional monoterpenes were emitted from the ecosystem that represented an important contribution to the total mixing ratio above the forest at night, and that must have been oxidized during the day before they escaped the forest canopy.

Lee, A.; Schade, G. W.; Holzinger, R.; Goldstein, A. H.

2004-12-01

103

Determination of longwave heat flux at the air-sea interface using measurements from buoy platforms  

SciTech Connect

A theory for pyrgeometer operation is utilized for determining downwelling longwave radiation. Errors in downwelling longwave radiation measurements are due to differences in pyrgeometer body and dome temperatures compared to that of the atmosphere. Additionally, incident shortwave radiation fluxes may be important. Using the present theory along with laboratory and field observations, it appears that downwelling longwave heat fluxes can be measured with errors less than 6 W/sq m. Longwave heat flux observations from surface buoys deployed in four different oceanic regions suggest that (1) incoming longwave measurements from buoys are repeatable, (2) uncertainties in radiometer calibration are significant and systematic, and (3) pyrgeometers are affected by direct and indirect solar heating. A hybrid measurement method for the determination of net longwave heat flux at the air-sea interface is described. The authors recommend improvement in calibration procedures as well as development of a radiometer to be used as a transfer standard to compare with in situ measurements. Uncertainties in sea surface skin temperature and emissivity are contributors to the error in the net longwave heat flux. However, a targeted error limit goal of +/- 10 W/sq m for the monthly mean net longwave heat flux appears to be achievable.

Dickey, T.D.; Manov, D.V.; Weller, R.A.; Siegel, D.A. [Univ. of Southern California, Los Angeles, CA (United States)]|[Woods Hole Oceanographic Institution, Woods Hole, MA (United States)]|[Univ. of California, Santa Barbara, CA (United States)

1994-08-01

104

Evaluating Surface Measured vs. Satellite-Retrieved Long-term Surface SW fluxes by Surface Climatological Type  

Microsoft Academic Search

This study compares an analysis of monthly average surface shortwave (SW) radiation measurements from 1983 through 1995 to SW fluxes from the newly released NASA\\/GEWEX Surface Radiation Budget Project (SRB). The NASA\\/GEWEX SRB dataset provides a twelve-year-plus (July 1983 to October 1995) global dataset of surface shortwave (SW) and longwave (LW) radiative parameters on a 1°x1° grid. The SW fluxes

M. Chiacchio; P. W. Stackhouse; S. J. Cox; S. K. Gupta; C. J. Mikovitz

2004-01-01

105

The surface shortwave net flux from the scanner for radiation budget (SCARAB)  

NASA Astrophysics Data System (ADS)

Shortwave surface net radiation is usually determined by combining the measurement of insolation with an independent estimate of surface albedo. However, uncertainties associated with each of these quantities may lead to large errors in the value of net surface solar radiation. An alternative approach is to deduce the net solar flux (the term flux is used here as the radiometric quantity flux density) at the surface directly from the budget at the top of the atmosphere, without explicit knowledge of surface albedo. The Satellite Application Facility on Climate Monitoring is a joint project of the German Meteorological Service and other European Meteorological Services dedicated to produce climate data sets using data from instruments onboard of METEOSAT Second Generation and polar orbiting satellites NOAA and METOP. In this context, it is planned to use the Li-Leighton algorithm as a validation tool for the independently derived solar incoming radiation at teh surface and the surface albedo. In the framework of the current development phase of the Satellite Application Facility on Climate Monitoring project, data from the well calibrated Scanner for Radiation Budget are used to apply the Li and Leighton algorithm to compute the shortwave surface net radiation.

Hollmann, R.; Bodas, A.; Gratzki, A.; Dammann, K.; Stuhlmann, R.

106

Scaling up flux measurements for the boreal forest using aircraft-tower combinations  

NASA Astrophysics Data System (ADS)

Fluxes of carbon dioxide, water vapor, sensible heat, and momentum obtained over the boreal forest from the Twin Otter aircraft and six tower-based systems are compared. These measurements were collected as part of the Boreal Ecosystem-Atmosphere Study (BOREAS) during three intensive field campaigns between May 25 and September 17, 1994. The representativeness of the tower-based measurements collected during BOREAS is discussed. Even though the net radiation from aircraft- and tower-based systems agreed well, in general, the aircraft tended to observe larger latent heat and smaller sensible heat fluxes than the towers. The CO2 fluxes from the aircraft were substantially less than from the tower, while the differences were relatively small for the momentum fluxes. The relationships between aircraft and tower-based flux measurements obtained by making repeated runs past various towers are used to scale up tower-based fluxes to a 16×16 km2 area near Prince Albert, Saskatchewan. It is demonstrated that except for a couple of cases primarily due to rapidly changing radiation conditions, this combination of measurements provides regional flux estimates of momentum, CO2, and sensible and latent heat similar to those obtained by flying a grid pattern over the area.

Desjardins, R. L.; MacPherson, J. I.; Mahrt, L.; Schuepp, P.; Pattey, E.; Neumann, H.; Baldocchi, D.; Wofsy, S.; Fitzjarrald, D.; McCaughey, H.; Joiner, D. W.

1997-12-01

107

Measuring biogenic carbon flux in the ocean  

SciTech Connect

Richard B. Rivkin et al. propose that neither food-web structure nor new production can be used to predict the magnitude or patterns of downward export of biogenic organic carbon (BC) from the euphotic zone, at least for the duration of their study. These conclusions depend critically on the observations that while both food-web structure and new production estimates were different during and after the spring phytoplankton bloom, the BC flux-as estimated using shallow surface-tethered sediment traps-was similar for the two periods. The authors argue that the uncertainties associated with the trap-derived BC flux estimates are too large to support these conclusions, and they offer an alternative explanation for the apparent similarity of bloom and post-bloom export fluxes. The response of the authors of the original article is also given. 22 refs., 1 fig.

Boyd, P. [Univ. of Otago, Dunedin (New Zealand); Newton, P. [Commissariat a l`Energie Atomique, Gif-sur-Yvette (France)

1997-01-24

108

Measurement of solar radiation  

SciTech Connect

There is provided a device for indicating the level of solar radiation intensity, and especially that region of the spectrum in the ultraviolet region which causes sunburn. The device may be provided with an output subdivided into a plurality of discrete levels of intensity indicated as numerals and figures. It may be provided with means of adjustment to the physiology of the user.

Braunstein, A.; Levite, T.; Sohar, E.

1984-11-27

109

Ambient Neutron Flux Measurements at Kimballton Underground Research Facility (KURF)  

NASA Astrophysics Data System (ADS)

It is important to accurately measure the ambient neutron flux at the Kimballton Underground Research Facility (KURF) in Virginia for the low background experiments housed there, some of which are associated with the Majorana project. This paper presents initial results for measurements of the neutron flux at KURF, which will be compared to those from other sites around the world.

Kaleko, David; Henning, Reyco; Tornow, Werner

2009-10-01

110

Measurements of eddy correlation oxygen fluxes in shallow freshwaters: Towards routine applications and analysis  

NASA Astrophysics Data System (ADS)

Benthic fluxes of dissolved oxygen are measured in a shallow reservoir using the eddy correlation technique. Flux variations depict the diurnal production-consumption cycle, with daytime oxygen release following the solar radiation trend. The average nighttime uptake of -40 +/- 11 mmol m-2 d-1 is in excellent agreement with the rate of -35 +/- 3 mmol m-2 d-1 derived from sediment oxygen microprofiles. Separating large-scale advective and turbulent fluctuations is a crucial and uncertain component of the flux computation and the largest source of error. To compensate for the 2.25 s oxygen sensor response time, the oxygen flux calculations are corrected by only ~5% using a first-order spectral enhancement. This work demonstrates that only a slightly faster oxygen sensor would be needed to resolve the entire flux spectrum. The 18 hours of data are the first measurements obtained in a freshwater reservoir that capture the diurnal oxygen production-consumption cycle.

McGinnis, Daniel F.; Berg, Peter; Brand, Andreas; Lorrai, Claudia; Edmonds, Theresa J.; Wüest, Alfred

2008-02-01

111

Measurements for the JASPER Program Flux Monitor Experiment  

SciTech Connect

The Flux Monitor Experiment was conducted at the Oak Ridge National Laboratory (ORNL) Tower Shielding Facility (TSF) during the months of May and June 1992, as part of the continuing series of eight experiments planned for the Japanese-American Shielding Program for Experimental Research (JASPER) program that was started in 1986. This series of experiments was designed to examine shielding concerns and radiation transport effects pertaining to in-vessel flux monitoring systems (FMS) in current reactor shield designs proposed for both the Advanced Liquid Metal Reactor (ALMR) design and the Japanese loop-type design. The program is a cooperative effort between the United States Department of Energy (US DOE) and the Japanese Power Reactor and Nuclear Fuel Development Corporation (PNC). The Tower Shielding Reactor H (TSR-II) neutron source was altered by the spectrum modifier (SM) used previously in the Axial Shield Experiment, and part of the Japanese Removable Radial Shield (RRS) before reaching the axial shield. In the axial shield were placed six homogeneous boron carbide (B{sub 4}C) hexagons around a center hexagon of aluminum used to represent sodium. Shield designs to be studied were placed beyond the axial shield, each design forming a void directly behind the axial shield. Measurements were made in the void and behind each slab as successive slabs were added.

Muckenthaler, F.J.; Spencer, R.R.; Hunter, H.T.; Hull, J.L. [Oak Ridge National Lab., TN (United States); Shono, A. [Power Reactor and Nuclear Fuel Development Corp., Oarai, Ibaraki (Japan). Oarai Engineering Center

1993-02-01

112

Measuring nitrate fluxes to assess estuarine eutrophication  

Microsoft Academic Search

Summary form only given.The availability of nitrate sensors has enabled integration of these instruments into real-time profiling buoys and, when coupled with current meters, allows for calculation of nitrate fluxes into and out of estuaries. As the United States' estuaries are increasingly experiencing eutrophication this technological development is timely. We report on the use of nitrate sensors on our profiling

J. Newton; A. Devol; W. Ruef

2009-01-01

113

Nonequilibrium radiative heat flux modeling for the Huygens entry probe  

Microsoft Academic Search

An electronic collisional-radiative model is proposed to predict the nonequilibrium populations and the radiation of the excited electronic states CN(A, B) and N2(A, B, C) during the entry of the Huygens probe into the atmosphere of Titan. The model is loosely coupled with flow solvers using a Lagrangian method. First, the model was tested against measurements obtained with the shock-tube

T. E. Magin; L. Caillault; A. Bourdon; C. O. Laux

2006-01-01

114

Sensitivity of shortwave radiative flux density, forcing, and heating rates to the aerosol vertical profile  

SciTech Connect

The effect of the aerosol vertical distribution on the solar radiation profiles, for idealized and measured profiles of optical properties (extinction and single-scattering albedo (SSA)) during the May 2003 Atmospheric Radiation Measurement (ARM) Aerosol Intensive Observation Period (AIOP), has been investigated using the Rapid Radiative Transfer Model Shortwave (RRTM_SW) code. Calculated profiles of down-welling and up-welling solar fluxes during the AIOP have been compared with the data measured by up- and down-looking solar broadband radiometers aboard a profiling research aircraft. The measured profiles of aerosol extinction, SSA, and water vapor obtained from the same aircraft that carried the radiometers served as the inputs for the model calculations. It is noteworthy that for this study, the uplooking radiometers were mounted on a stabilized platform that kept the radiometers parallel with respect to the earth’s horizontal plane. The results indicate that the shape of the aerosol extinction profiles has very little impact on direct radiative forcings at the top of atmosphere and surface in a cloud-free sky. However, as long as the aerosol is not purely scattering, the shape of the extinction profiles is important for forcing profiles. Identical extinction profiles with different absorption profiles drastically influence the forcing and heating rate profiles. Using aircraft data from 19 AIOP profiles over the Southern Great Plains (SGP), we are able to achieve broadband down-welling solar flux closure within 0.8% (bias difference) or 1.8% (rms difference), well within the expected measurement uncertainty of 1 to 3%. The poorer agreement in up-welling flux (bias -3.7%, rms 10%) is attributed to the use of inaccurate surface albedo data. The sensitivity tests reveal the important role accurate, vertically resolved aerosol extinction data plays in tightening flux closure. This study also suggests that in the presence of a strongly absorbing substance, aircraft flux measurements from a stabilized platform have the potential to determine heating rate profiles. These measurement-based heating rate profiles provide useful data for heating rate closure studies and indirect estimates of single scattering albedo assumed in radiative transfer calculations.

Guan, Hong; Schmid, Beat; Bucholtz, Anthony; Bergstrom, Robert

2010-03-31

115

Uncertainty analysis of steady state incident heat flux measurements in hydrocarbon fuel fires.  

SciTech Connect

The objective of this report is to develop uncertainty estimates for three heat flux measurement techniques used for the measurement of incident heat flux in a combined radiative and convective environment. This is related to the measurement of heat flux to objects placed inside hydrocarbon fuel (diesel, JP-8 jet fuel) fires, which is very difficult to make accurately (e.g., less than 10%). Three methods will be discussed: a Schmidt-Boelter heat flux gage; a calorimeter and inverse heat conduction method; and a thin plate and energy balance method. Steady state uncertainties were estimated for two types of fires (i.e., calm wind and high winds) at three times (early in the fire, late in the fire, and at an intermediate time). Results showed a large uncertainty for all three methods. Typical uncertainties for a Schmidt-Boelter gage ranged from {+-}23% for high wind fires to {+-}39% for low wind fires. For the calorimeter/inverse method the uncertainties were {+-}25% to {+-}40%. The thin plate/energy balance method the uncertainties ranged from {+-}21% to {+-}42%. The 23-39% uncertainties for the Schmidt-Boelter gage are much larger than the quoted uncertainty for a radiative only environment (i.e ., {+-}3%). This large difference is due to the convective contribution and because the gage sensitivities to radiative and convective environments are not equal. All these values are larger than desired, which suggests the need for improvements in heat flux measurements in fires.

Nakos, James Thomas

2005-12-01

116

First eddy covariance flux measurements by PTR-TOF  

NASA Astrophysics Data System (ADS)

The recently developed PTR-TOF instrument was evaluated to measure methanol fluxes emitted from grass land using the eddy covariance method. The high time resolution of the PTR-TOF allowed storing full mass spectra up to m/z 315 with a frequency of 10 Hz. Three isobaric ions were found at a nominal mass of m/z 33 due to the high mass resolving power of the PTR-TOF. Only one of the three peaks contributed to eddy covariance fluxes. The exact mass of this peak agrees well with the exact mass of protonated methanol (m/z 33.0335). The eddy covariance methanol fluxes measured with PTR-TOF were compared to virtual disjunct eddy covariance methanol fluxes simultaneously measured with a conventional PTR-MS. The methanol fluxes from both instruments show excellent agreement.

Müller, M.; Graus, M.; Ruuskanen, T. M.; Schnitzhofer, R.; Bamberger, I.; Kaser, L.; Titzmann, T.; Hörtnagl, L.; Wohlfahrt, G.; Karl, T.; Hansel, A.

2009-12-01

117

First eddy covariance flux measurements by PTR-TOF  

NASA Astrophysics Data System (ADS)

The recently developed PTR-TOF instrument was evaluated to measure methanol fluxes emitted from grass land using the eddy covariance method. The high time resolution of the PTR-TOF allowed storing full mass spectra up to m/z 315 with a frequency of 10 Hz. Three isobaric ions were found at a nominal mass of m/z 33 due to the high mass resolving power of the PTR-TOF. Only one of the three peaks contributed to eddy covariance fluxes. The exact mass of this peak agrees well with the exact mass of protonated methanol (m/z 33.0335). The eddy covariance methanol fluxes measured with PTR-TOF were compared to virtual disjunct eddy covariance methanol fluxes simultaneously measured with a conventional PTR-MS. The methanol fluxes from both instruments show excellent agreement.

Müller, M.; Graus, M.; Ruuskanen, T. M.; Schnitzhofer, R.; Bamberger, I.; Kaser, L.; Titzmann, T.; Hörtnagl, L.; Wohlfahrt, G.; Karl, T.; Hansel, A.

2010-03-01

118

Rotor Losses Measurements in an Axial Flux Permanent Magnet Machine  

Microsoft Academic Search

MMF space harmonics and slot openings produce considerable rotor losses in permanent magnet (PM) machines, especially if fractional-slot windings are adopted. This paper aims to measure the rotor losses of a 12-slot 10-pole axial flux phase modulation machine. Both MMF space harmonics and slot open- ings are considered. The prototype is an axial flux machine with open slots, equipped with

Luigi Alberti; Emanuele Fornasiero; Nicola Bianchi; Silverio Bolognani

2011-01-01

119

Seasonality of Overstory and Understory Fluxes in a Semi-Arid Oak Savanna: What can be Learned from Comparing Measured and Modeled Fluxes?  

NASA Astrophysics Data System (ADS)

Semi-arid climates experience large seasonal and inter-annual variability in radiation and precipitation, creating natural conditions adequate to study how year-to-year changes affect atmosphere-biosphere fluxes. Especially, savanna ecosystems, that combine tree and below-canopy components, create a unique environment in which phenology dramatically changes between seasons. We used a 10-year flux database in order to define seasonal and interannual variability of climatic inputs and fluxes, and evaluate model capability to reproduce observed variability. This is based on the perception that model capability to construct the deviation, and not the average, is important in order to correctly predict ecosystem sensitivity to climate change. Our research site is a low density and low LAI (0.8) semi-arid savanna, located at Tonzi Ranch, Northern California. In this system, trees are active during the warm season (Mar - Oct), and grasses are active during the wet season (Dec - May). Measurements of carbon and water fluxes above and below the tree canopy using eddy covariance and supplementary measurements have been made since 2001. Fluxes were simulated using bio-meteorological process-oriented ecosystem models: BEPS and 3D-CAONAK. Models were partly capable of reproducing fluxes on daily scales (R2=0.66). We then compared model outputs for different ecosystem components and seasons, and found distinct seasons with high correlations while other seasons were purely represented. Comparison was much higher for ET than for GPP. The understory was better simulated than the overstory. CANOAK overestimated spring understory fluxes, probably due to the capability to directly calculated 3D radiative transfer. BEPS underestimated spring understory fluxes, following the pre-description of grass die-off. Both models underestimated peak spring overstory fluxes. During winter tree dormant, modeled fluxes were null, but occasional high fluxes of both ET and GPP were measured following precipitation events, likely produced by an adverse measurement effect. This analysis enabled to pinpoint specific areas where models break, and stress that model capability to reproduce fluxes vary among seasons and ecosystem components. The combined response was such, that comparison decreases when ecosystem fluxes were partitioned between overstory and understory fluxes. Model performance decreases with time scale; while performance was high for some seasons, models were less capable of reproducing the high variability in understory fluxes vs. the conservative overstory fluxes on annual scales. Discrepancies were not always a result of models' faults; comparison largely improved when measurements of overstory fluxes during precipitation events were excluded. Conclusions raised from this research enable to answer the critical question of the level and type of details needed in order to correctly predict ecosystem respond to environmental and climatic change.

Raz-Yaseef, N.; Sonnentag, O.; Kobayashi, H.; Chen, J. M.; Verfaillie, J. G.; Ma, S.; Baldocchi, D. D.

2011-12-01

120

Determination of top-of-atmosphere longwave radiative fluxes: A comparison between two approaches using ScaRaB data  

NASA Astrophysics Data System (ADS)

Two conceptually different approaches (broadband-based ERBE (Earth Radiation Budget Experiment) and narrowband-based ISCCP (International Satellite Cloud Climatology Project) approaches), used to derive the TOA (top of atmosphere) longwave radiative fluxes, are compared using the ScaRaB simultaneous narrowband and broadband measurements. Except for very thin cirrus clouds, differences between the ERBE and the ISCCP approaches are in general <10 W m-2 for the TOA LW radiative fluxes. For clear pixels the model-calculated (ISCCP approach) TOA LW radiances are systematically smaller than the observations. Compared with the radiative transfer model used in this study, the ERBE LW angular dependence models are too weakly limb darkened for optically thin clouds but too strongly limb darkened for optically thick clouds, suggesting that more accurate instantaneous TOA LW flux estimations from the ERBE approach would require additional cloud classes based on cloud height and optical thickness.

Chen, Ting; Rossow, William B.

2002-04-01

121

Evaluation of multi-dimensional flux models for radiative transfer in cylindrical combustion chambers  

NASA Astrophysics Data System (ADS)

Four flux-type models for radiative heat transfer in cylindrical configurations were applied to the prediction of radiative flux density and source term of a cylindrical enclosure problem based on data reported previously on a pilot-scale experimental combustor with steep temperature gradients. The models, which are Schuster-Hamaker type four-flux model derived by Lockwood and Spalding, two Schuster-Schwarzschild type four-flux models derived by Siddall and Selcuk and Richter and Quack and spherical harmonics approximation, were evaluated from the viewpoint of predictive accuracy by comparing their predictions with exact solutions produced previously. The comparisons showed that spherical harmonics approximation produces more accurate results than the other models with respect to the radiative energy source term and that the four-flux models of Lockwood and Spalding and Siddall and Selcuk for isotropic radiation field are more accurate with respect to the prediction of radiative flux density to the side wall.

Selcuk, Nevin

1993-02-01

122

Solar and thermal radiation profiles and radiative forcing measured through the atmosphere  

NASA Astrophysics Data System (ADS)

Solar shortwave and thermal longwave radiation at the Earth's surface and at the top of the atmosphere is commonly measured at surface stations, from airplanes and from satellites. Here we show radiative flux profiles measured with radiosondes ascending from the Earth's surface to 35 km into the stratosphere. During two-hour flights solar shortwave and thermal longwave radiation are measured both downward and upward with four individual sensors. Daytime solar and thermal radiation is compared to nighttime measurements and 24-hour average radiation budget profiles are shown through the atmosphere. However, of even greater importance with regard to climate change are measured upward and downward longwave greenhouse radiation profiles. Their changes with temperature and water vapor enable direct measurement of radiative forcing through the atmosphere. Measurements during two cloud-free nights with different temperature and different water vapor amount, show an almost equal but opposite net longwave radiation change, or water vapor greenhouse forcing, downwards to the surface and upward into space. Radiative flux profiles clearly illustrate the Earth's atmospheric greenhouse effect, and allow important investigations of clouds and other atmospheric constituents and their effects on shortwave reflection, as well as longwave emission towards the surface and into space.

Philipona, Rolf; Kräuchi, Andreas; Brocard, Emmanuel

2012-07-01

123

Comparison of general circulation models to Earth Radiation Budget Experiment data: Computation of clear-sky fluxes  

SciTech Connect

The recent availability of top-of-the-atmosphere radiometric measurements from the Earth Radiation Budget Experiment provides important opportunities for testing and improving numerical climate models. What is unique about these satellite data is that they provide monthly mean clear-sky measurements. There is, however, considerable confusion as to evaluating clear-sky radiative fluxes in climate models in a manner that is consistent with the satellite data processing system. This study provides a clear-sky flux computation method that serves as an analog to the data processing procedure and so provides a model diagnostic that is consistent with the processed satellite data. 11 refs., 4 figs., 5 tabs.

Cess, R.D. (State Univ. of New York, Stony Brook (United States)); Potter, G.L.; Gates, W.L.; Corsetti, L. (Lawrence Livermore National Lab., CA (United States)); Morcrette, J.J. (European Centre for Medium-Range Weather Forecasts, Reading, Berkshire (United Kingdom))

1992-12-20

124

Validation experiments to determine radiation partitioning of heat flux to an object in a fully turbulent fire.  

SciTech Connect

It is necessary to improve understanding and develop validation data of the heat flux incident to an object located within the fire plume for the validation of SIERRA/ FUEGO/SYRINX fire and SIERRA/CALORE. One key aspect of the validation data sets is the determination of the relative contribution of the radiative and convective heat fluxes. To meet this objective, a cylindrical calorimeter with sufficient instrumentation to measure total and radiative heat flux had been designed and fabricated. This calorimeter will be tested both in the controlled radiative environment of the Penlight facility and in a fire environment in the FLAME/Radiant Heat (FRH) facility. Validation experiments are specifically designed for direct comparison with the computational predictions. Making meaningful comparisons between the computational and experimental results requires careful characterization and control of the experimental features or parameters used as inputs into the computational model. Validation experiments must be designed to capture the essential physical phenomena, including all relevant initial and boundary conditions. A significant question of interest to modeling heat flux incident to an object in or near a fire is the contribution of the radiation and convection modes of heat transfer. The series of experiments documented in this test plan is designed to provide data on the radiation partitioning, defined as the fraction of the total heat flux that is due to radiation.

Ricks, Allen; Blanchat, Thomas K.; Jernigan, Dann A.

2006-06-01

125

Flux Measurements of Volatile Organic Compounds from an Urban Landscape  

SciTech Connect

Direct measurements of volatile organic compound (VOC) emissions that include all anthropogenic and biogenic emission sources in urban areas are a missing requirement to evaluate emission inventories and constrain current photochemical modelling practices. Here we demonstrate the use of micrometeorological techniques coupled with fast-response sensors to measure urban VOC fluxes from a neighborhood of Mexico City, where the spatial variability of surface cover and roughness is high. Fluxes of olefins, methanol, acetone, toluene and C2-benzenes were measured and compared with the local gridded emission inventory. VOC fluxes exhibited a clear diurnal pattern with a strong relationship to vehicular traffic. Recent photochemical modeling results suggest that VOC emissions are significantly underestimated in Mexico City1, but the measured VOC fluxes described here indicate that the official emission inventory2 is essentially correct. Thus, other explanations are needed to explain the photochemical modelling results.

Velasco, E.; Lamb, Brian K.; Pressley, S.; Allwine, Eugene J.; Westberg, Halvor; Jobson, B Tom T.; Alexander, M. Lizabeth; Prazeller, Peter; Molina, Luisa; Molina, Mario J.

2005-10-19

126

Radiation budget measurements for the eighties and nineties  

SciTech Connect

The Earth Radiation Budget Experiment (ERBE) consisted of a scanning radiometer and non-scanning radiometers on each of three spacecraft. These instruments began flying in October 1984. The nonscanning radiometers continue to operate, providing broadband radiation measurements of the Earth's outgoing longwave radiation and reflected solar radiation, in addition to measurements of the solar output. The Clouds and Earth Radiant Energy System (CERES) features a scanning radiometer, which is an improved version of the ERBE scanning radiometer, and will fly on the Tropical Rainfall Measurement Mission and Earth Observation System platforms in the late nineties. The CERES project will provide not only radiant fluxes at the top of the atmosphere' (TOA), but also at the surface and will compute radiant flux divergence through the atmosphere.

Smith, G.L.; Barkstrom, B.R.; Harrison, E.F.; Lee, R.B. III; Wielicki, B.A. (NASA, Langley Research Center, Hampton, VA (United States))

1994-01-01

127

Modeling thermal behavior and work flux in finite-rate systems with radiation  

Microsoft Academic Search

We apply thermodynamic analysis in modeling, simulation and optimization of radiation engines as non-linear energy converters. We also perform critical analysis of available data for photon flux and photon density that leads to exact numerical value of photon flux constant. Basic thermodynamic principles lead to expressions for converter’s efficiency and generated work in terms of driving energy flux in the

Stanislaw Sieniutycz; Piotr Kuran

2006-01-01

128

Measuring Regional CO2 Fluxes Using a Lagrangian Approach  

NASA Astrophysics Data System (ADS)

The difficulty of measuring regional fluxes of CO2 has limited our understanding of the global carbon budget and the processes controlling carbon exchange across politically relevant spatial scales. A Lagrangian experiment was conducted over Iowa on June 19, 2007 as part of the North American Carbon Program's Mid-Continent Intensive using a light-weight, cost-effective aircraft to measure a net drawdown of CO2 concentration within the boundary layer. The drawdown is related to photosynthetic uptake when emission footprints are considered using a combination of emission inventories from the Vulcan project and HYSPLIT source contributions. Entrainment through the top of the boundary layer is measured directly using turbulence measurements from an onboard probe capable of measuring winds in 3-dimensions. Results show a total average CO2 flux of -5.3±0.7 ?mol m-2 s-1. The average flux from fossil fuels over the measurement area is 2.8±0.4 ?mol m-2 s-1. Thus, the CO2 flux attributable to the vegetation is -8.1±0.8 ?mol m-2 s-1. The magnitude of the vegetative flux is comparable to other studies using the Lagrangian approach, but it is smaller than tower- based eddy covariance fluxes over the same period and measurement area. Sensitivities to analysis procedures and discrepancies between aircraft and tower-based measurements are discussed. We describe an aircraft Lagrangian experiment that offers direct, reliable, and cost-effective means for measuring CO2 fluxes at regional scales that can be used to compare to ecosystem models or to satellite measurements.

Martins, D. K.; Sweeney, C.; Stirm, B. H.; Shepson, P. B.

2008-12-01

129

Thin-cavity interferometric sensors for detection of weak radiation flux and microvibrations  

Microsoft Academic Search

Novel optical sensors for the detection of weak radiation flux transients and mechanical micro-vibrations have been developed. The sensors are based on the modulation of an interference pattern created during the optical interrogation of a thin air cavity similar to a low finesse Fabry-Perot or Fizeau interferometer, formed between two parallel glass holographic plates. In the detection of radiation flux

Maurice Whelan; Robert P. Kenny; John T. Sheridan; Constantin T. Coutsomitros

1996-01-01

130

Forestation of boreal peatlands: Impacts of changing albedo and greenhouse gas fluxes on radiative forcing  

Microsoft Academic Search

We estimated the magnitude of the radiative forcing (RF) due to changes in albedo following the forestation of peatlands, and calculated the net RF by taking into account the changes in both the albedo and the greenhouse gas (GHG) fluxes during one forest rotation. Data on radiation, tree biomass, and soil GHG fluxes were combined with models for canopy cover,

Annalea Lohila; Kari Minkkinen; Jukka Laine; Ilkka Savolainen; Juha-Pekka Tuovinen; Lauri Korhonen; Tuomas Laurila; Hanna Tietäväinen; Ari Laaksonen

2010-01-01

131

Techniques and Methods used to determine the Best Estimate of Radiation Fluxes at SGP Central Facility  

SciTech Connect

The DOE ARM Program operates three independent surface radiation measurement systems co-located within a few meters at the Southern Great Plains Central Facility (SGP CF) site. This redundancy affords a unique opportunity for producing a high quality estimate of the actual continuous irradiance record. The Best Estimate Radiation Flux Value Added Product (VAP) currently being developed for ARM (beflux1long VAP) is attempting to determine the best estimate value for each radiation field from these multiple measurements as an operational product. In the development of this VAP, it is necessary to assess the nominal long-term unattended operational accuracy (as opposed to accuracy assessments based on calibrations or short term attended operation) to screen the data for quality assessment. We will present statistical results of this assessment, including our estimates of nominal operational accuracies, and the amount of data that pass the resultant data quality testing. Central to data quality assessment is the notion that having three pieces of information allows one not only to detect measurement problems, but to identify which of the three similar measurements is likely to be in error. We will discuss the techniques we have developed to use similar, but often differing, measurement data as comparison tools for operationally detecting measurement errors. We will also present statistical analyses of the resultant best estimate radiation climatology for the SGP CF.

Shi, Yan; Long, Charles N.

2002-07-30

132

Solar and thermal radiation in Jupiter's atmosphere: initial results of the Galileo probe net flux radiometer.  

PubMed

The Galileo probe net flux radiometer measured radiation within Jupiter's atmosphere over the 125-kilometer altitude range between pressures of 0.44 bar and 14 bars. Evidence for the expected ammonia cloud was seen in solar and thermal channels down to 0.5 to 0.6 bar. Between 0.6 and 10 bars large thermal fluxes imply very low gaseous opacities and provide no evidence for a deep water cloud. Near 8 bars the water vapor abundance appears to be about 10 percent of what would be expected for a solar abundance of oxygen. Below 8 bars, measurements suggest an increasing water abundance with depth or a deep cloud layer. Ammonia appears to follow a significantly subsaturated profile above 3 bars. Unexpectedly high absorption of sunlight was found at wavelengths greater than 600 nanometers. PMID:8629018

Sromovsky, L A; Best, F A; Collard, A D; Fry, P M; Revercomb, H E; Freedman, R S; Orton, G S; Hayden, J L; Tomasko, M G; Lemmon, M T

1996-05-10

133

Hybrid heat flux measurement system for solar central receiver evaluation  

Microsoft Academic Search

A hybrid heat flux measurement system has been designed, built and mounted on top of the SSPS-CRS tower at the Plataforma Solar de Almería (PSA) to measure the incident solar power that is concentrated by a heliostat field on the flat aperture of a central receiver. This device is composed of two measurement systems, one direct and the other indirect.

J. Ballestrín; R. Monterreal

2004-01-01

134

Standard measuring system for calibration of magnetic flux density gradiometers  

Microsoft Academic Search

A standard measuring system (setup) has been developed at VNIIM to be used for the calibration of magnetic flux density gradient (MFDG) coils, sensors and magnetic gradiometers (MG). This measurement standard is based on the calculable quartz coil used for the reproduction of gradient which is uniform in a specified working space. It also includes measuring equipment to compare coils,

V. N. Khorev; V. Y. Shifrin; S. A. Shubin; P. G. Park

2010-01-01

135

Flux and brightness calculations for various synchrotron radiation sources  

SciTech Connect

Synchrotron radiation (SR) storage rings are powerful scientific and technological tools. The first generation of storage rings in the US., e.g., SURF (Washington, D.C.), Tantalus (Wisconsin), SSRL (Stanford), and CHESS (Cornell), revolutionized VUV, soft X-ray, and hard X-ray science. The second (present) generation of storage rings, e.g. the NSLS VUV and XRAY rings and Aladdin (Wisconsin), have sustained the revolution by providing higher stored currents and up to a factor of ten smaller electron beam sizes than the first generation sources. This has made possible a large number of experiments that could not performed using first generation sources. In addition, the NSLS XRAY ring design optimizes the performance of wigglers (high field periodic magnetic insertion devices). The third generation storage rings, e.g. ALS (Berkeley) and APS (Argonne), are being designed to optimize the performance of undulators (low field periodic magnetic insertion devices). These extremely high brightness sources will further revolutionize x-ray science by providing diffraction-limited x-ray beams. The output of undulators and wigglers is distinct from that of bending magnets in magnitude, spectral shape, and in spatial and angular size. Using published equations, we have developed computer programs to calculate the flux, central intensity, and brightness output bending magnets and selected wigglers and undulators of the NSLS VUV and XRAY rings, the Advanced Light Source (ALS), and the Advanced Photon Source (APS). Following is a summary of the equations used, the graphs and data produced, and the computer codes written. These codes, written in the C programming language, can be used to calculate the flux, central intensity, and brightness curves for bending magnets and insertion devices on any storage ring.

Weber, J.M.; Hulbert, S.L.

1991-11-01

136

The Measurement of Radiation Dose in SJ-10 satellite  

NASA Astrophysics Data System (ADS)

SJ-10 scientific satellite will be launched after a few years in china. The SJ-10 satellite is a recoverable satellite researching for materials and life science. Orbit altitude of 600 km circular orbit with an inclination of 63 " Space Radiation Biology Researching " is a sub-project in SJ-10 satellite, which will research the relation between the biological effect and space particle's radiation. The project include the biological materials for biological effect researching and "The Detector of Space Radiation Biology " for measurement the dose in the space. In SJ-10 satellite's orbit, The source of the particle radiation is from earth radiation-belt and galaxy cosmic ray . The propose of "The Detector of space radiation biology " is monitor the particle radiation, service to the scientific analysis. The instrument include the semiconductor particle radiation monitoring package and Tissue-equivalent particle radiation monitoring package. The semiconductor particle radiation monitoring package is used to detect the flux of the protons, electrons and heavy ions, also the linear energy transfer(LET) in the silicon material. The element composition of Tissue-equivalent particle radiation monitoring package is similar to the biology issue. It can measure the space particles in biological materials, the value of the LET, dose, dose equivalent, and more Keywords: SJ-10 satellites; radiation biological effects; semiconductor particle radiation moni-toring package; Tissue-equivalent particle radiation monitoring package

Shenyi, Zhang

137

Seasonal Characteristics of Surface Meteorological and Radiative Fluxes on the East Rongbuk Glacier in Mt. Qomolangma (the Mt. Everest) Region  

Microsoft Academic Search

Ground-based measurements are essential for understanding alpine glacier dynamics, especially in remote regions where in-situ measurements are extremely limited. The meteorological and radiative fluxes were measured over the accumulation area on the East Rongbuk Glacier, Mt. Qomolangma (the Mt. Everest) at elevation of 6,560 m a.s.l. Measurements were conducted using an automatic weather station (AWS) from May 1 through July

X. Yang; T. Zhang; D. Qin; S. Kang; X. Qin; H. Liu

2008-01-01

138

Noninvasive measurement of pulmonary transvascular protein flux in normal man.  

PubMed

Onset of lung edema is usually associated with increase in the pulmonary transvascular flux of water and proteins. Clinical measurement of these parameters may aid in early diagnosis of pulmonary edema, and allow differentiation between "cardiogenic" and "noncardiogenic" types base on the magnitude of the detected changes. We have previously described a noninvasive method for estimating transvascular protein flux in lung (Gorin, A. B., W. J. Weidner, R. H. Demling, and N. C. Staub, 1978. Noninvasive measurement of pulmonary transvascular protein flux in sheep. J. Appl. Physiol. 45: 225-233). Using this method we measured the net transvascular flux of [113mIn]transferrin (mol wt, 76,000 in lungs of nine normal human volunteers. Plasma clearance of [113In]transferrin occurred with a T1/2 = 7.0 +/- 2.6 h (mean +/- SD). The pulmonary transvascular flux coefficient, alpha, was 2.9 +/- 1.4 X 10(-3) ml/s (mean +/- SD) in man, slightly greater than that previously measured in sheep (2.7 +/- 0.7 X 10(-3) ml/s; mean +/- SD). The pulmonary transcapillary escape rate is twofold greater than the transcapillary escape rate for the vascular bed as a whole, indicating a greater "porosity" of exchanging vessels in the lung than exists for the "average" microvessel in the body. Time taken to reach half-equilibrium concentration of tracer protein in the lung interstitium was quite short, 52 +/- 13 min (mean +/- SD). We have shown that measurement of pulmonary transvascular protein flux in man is practical. The coefficient of variation of measurements of alpha (between subjects) was 0.48, and of measurements of pulmonary transcapillary escape rates was 0.39. In animals, endothelial injury commonly results in a two- to threefold increase in transvascular protein flux. Thus, external radioflux detection should be a suitable means of quantitating lung vascular injury in human disease states. PMID:7430349

Gorin, A B; Kohler, J; DeNardo, G

1980-11-01

139

Measurements of x-ray spectral flux of high brightness undulators by gas scattering  

SciTech Connect

Absolute radiation flux and polarization measurements of the Advanced Photon Source (APS) undulators may have to be made under high thermal loading conditions. A method that may circumvent the high-heat-load problem was tested during a recent APS/CHESS undulator run. The technique makes use of a Si(Li) energy-dispersive detector to measure 5--35 keV x rays scattered from a well-defined He gas volume at controlled pressure.

Ilinski, P.; Yun, W.; Lai, B.; Gluskin, E.; Cai, Z. (Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States))

1995-02-01

140

Reconciling main belt asteroid spectral flux density measurements with a self-consistent thermophysical model  

NASA Astrophysics Data System (ADS)

Thermophysical models consistent with Earth's Moon and infrared and submillimeter measurements obtained during the Rosetta fly-by of Asteroid (21) Lutetia have been applied to computations of thermal fluxes from Asteroids (4) Vesta, (1) Ceres, (2) Pallas, and (10) Hygiea. Comparisons are made with Earth- and space-based flux measurements that cover the infrared-to-centimeter wavelength spectrum. The models account for diurnal and seasonal effects as well as viewing geometry at the epochs of the observational data. Model fluxes at submillimeter and longer wavelengths are computed from a radiative transfer integral that takes into account temperature gradients in the subsurface and a plausible range of lunar-like electrical properties. A surface roughness model in the form of hemispherical mini-craters is included in the evaluation of the infrared flux comparisons. Results of the infrared-to-centimeter comparisons confirm that low thermal inertia (I ˜ 5-80 J/(K m2 s0.5)) material constitutes the upper ˜1 cm of the four large asteroids studied. For the non-isothermal models considered, spectral emissivities near 1.0 fit the data of all four asteroids with no significant variations indicated throughout the infrared to microwave spectrum. Enhanced measured infrared flux levels (relative to a smooth surface model) of the four asteroids are constrained by a surface model with up to 50% fractional coverage of hemispherical craters, consistent with both the recent Lutetia result and historical measurements of the Moon's thermal flux characteristics.

Keihm, Stephen; Kamp, Lucas; Gulkis, Samuel; Hofstadter, Mark; Lee, Seungwon; Janssen, Michael; Choukroun, Mathieu

2013-09-01

141

Absolute flux measurement at HIGS using Compton backscattering  

Microsoft Academic Search

The High Intensity gamma-ray Source (HIgammaS) at FELL\\/TUNL is developing a program to study many aspects of nuclear physics presently using 2-to-50 MeV gamma-rays. In many cases these experiments require absolute gamma-flux monitoring and determination. This project presents a technique to indirectly measure the absolute gamma-ray flux by placing a thin scattering foil in the gamma-beam and then detecting the

B. Fallin; M. W. Ahmed; B. Perdue; A. Sabourov; T. Sheard; W. Tornow; A. P. Tonchev; H. R. Weller; J. Li; I. V. Pinaev; Y. Wu; R. M. Prior; M. Spraker; J. Chen; G. Feldman

2003-01-01

142

The air density correction to eddy flux measurements  

Microsoft Academic Search

Under the usual assumptions for the atmospheric surface layer, we show that air density fluctuations, particularly those due\\u000a to temperature fluctuations associated with a heat flux, result in a small mean vertical wind velocity. Because of this, there\\u000a can be a significant correction to eddy flux measurements of passive scalars, for example CO2, whose average concentration is very large compared

E. P. Jones; S. D. Smith

1978-01-01

143

High flux-fluence measurements in fast reactors  

Microsoft Academic Search

Characterization of irradiation environments for fuels and materials tests in fast reactors requires determination of the neutron flux integrated over times as long as several years. An accurate integration requires, therefore, passive dosimetry monitors with long half-life or stable products which can be conveniently measured. In addition, burn-up, burn-in, and burn-out effects must be considered in high flux situations and

E. P. Lippincott; J. A. Ulseth

1977-01-01

144

FluxPro: Real time monitoring and simulation system for eddy covariance flux measurement  

NASA Astrophysics Data System (ADS)

To cope with unusual weather changes on crop cultivation in a field level, prompt and precise monitoring of photosynthesis and evapotranspiration, and those fast and reliable forecasting are indispensable. So we have developed FluxPro which is simultaneous operating system of the monitoring and the forecasting. The monitoring subsystem provides vapor and CO2 fluxes with uncertainty to understand the live condition of photosynthesis and evapotranspiration by open-path eddy covariance flux measurement (EC) system and self-developed EC tolerance analysis scheme. The forecasting subsystem serves the predicted fluxes with anomaly based on model parameter assimilation to estimate the hourly or daily water consumption and carbon assimilation during a week by multi-simulation package consisting of various models from simple to complicate. FluxPro is helpful not only to detect a critical condition of growing crop in terms of photosynthesis and evapotranspiration but also to decide time and amount of launching control for keeping those optimization condition when an unusual weather event is arisen. In our presentation, we will demonstrate the FluxPro operated at tangerine orchard in Jeju, Korea.

Kim, W.; Seo, H.; Mano, M.; Ono, K.; Miyata, A.; Yokozawa, M.

2010-12-01

145

Sampling errors in the vertical fluxes of potential temperature and moisture measured by aircraft during FIFE  

NASA Astrophysics Data System (ADS)

The First International Satellite Land Surface Climatology Project (ISLSCP) Field Experiment (FIFE) was carried out over a 15 × 15 km area in central Kansas [Sellers et al., this issue]. The site size was constrained by land use characteristics, topography, and, importantly, the ability to field a reasonable network of surface observations of plant physiology, soil moisture, and radiative characteristics as well as surface observations of meteorological observations, including vertical fluxes of sensible heat and moisture. As described by Kelly [this issue], aircraft flying within the atmospheric boundary layer over the FIFE site played an important role: they provided direct measurements of the vertical fluxes of sensible heat and moisture above the FIFE site. Potential temperature flux and sensible heat flux differ by the constant ?dcp, where ?d is the dry air density (which is nearly constant in the atmospheric boundary layer) and cp is the specific heat of dry air at constant pressure.

Grossman, Robert L.

1992-11-01

146

Determination of top-of-atmosphere longwave radiative fluxes: A comparison between two approaches using ScaRaB data  

Microsoft Academic Search

Two conceptually different approaches (broadband-based ERBE (Earth Radiation Budget Experiment) and narrowband-based ISCCP (International Satellite Cloud Climatology Project) approaches), used to derive the TOA (top of atmosphere) longwave radiative fluxes, are compared using the ScaRaB simultaneous narrowband and broadband measurements. Except for very thin cirrus clouds, differences between the ERBE and the ISCCP approaches are in general <10 W m-2

Ting Chen; William B. Rossow

2002-01-01

147

FT-IR measurements of emissivity and temperature during high flux solar processing  

SciTech Connect

The experimental capability to generate and utilize concentrated solar flux has been demonstrated at a number of facilities in the US. To advance this research area, the National Renewable Energy Laboratory (NREL) has designed and constructed a versatile High Flux Solar Furnace (HFSF). Research is ongoing in areas of material processing, high temperature and UV enhanced detoxification, chemical synthesis, high flux optics, solar pumped lasers, and high heating rate processes. Surface modifications via concentrated solar flux, however, are currently performed without the means to accurately monitor the temperature of the surface of interest. Thermoelectric and pyrometric devices are not accurate due to limitations in surface contact and knowledge of surface emissivity, respectively, as well as interference contributed by the solar flux. In this article, the authors present a noncontact optical technique that simultaneously measures the directional spectral emissivity, and temperature of the surface during solar processing. A Fourier Transform Infrared (FT-IR) spectrometer is coupled to a processing chamber at NREL`s HFSF with a fiber-optic radiation transfer assembly. The system measures directional emission and hemispherical-directional reflectance in a spectral region that lacks contribution from solar flux. From these radiative property measurements during solar processing, the spectral emittance and temperature at the measurement point can be obtained. The methodology, validation measurements, and in-situ measurements during solar processing of materials are presented. Knowledge of surface temperature during solar processing is an important parameter for process control. Based on validation measurements for spectral emittance, the temperature error associated with the novel instrument is less than {+-} 5% for surfaces of mid-range emittance.

Markham, J.R.; Smith, W.W.; Haigis, J.R. [Advanced Fuel Research, Inc., East Hartford, CT (United States)] [and others

1996-02-01

148

Radiation measurement on the International Space Station.  

PubMed

The results of an investigation of radiation environment on board the ISS with apogee/perigee of 420/380 km and inclination 51.6 degrees are presented. For measurement of important characteristics of cosmic rays (particles fluxes, LET spectrum, equivalent doses and heavy ions with Z > or = 2) a nuclear photographic emulsion as a controllable threshold detector was used. The use of this detector permits a registration of the LET spectrum of charged particles within wide range of dE/dx and during the last years it has already been successfully used on board the MIR station, Space Shuttles and "Kosmos" spacecrafts. An integral LET spectrum was measured in the range 0.5-2.2 x 10(3) keV/micrometers and the value of equivalent dose 360 microSv/day was estimated. The flux of biologically dangerous heavy particles with Z > or = 2 was measured (3.85 x 10(3) particles/cm2). PMID:15856556

Akopova, A B; Manaseryan, M M; Melkonyan, A A; Tatikyan, S Sh; Potapov, Yu

2005-02-01

149

On the Measurement of Soil Heat Flux to Improve Estimates of Energy Balance Closure  

NASA Astrophysics Data System (ADS)

Measurements of soil heat flux (G) are required to test for energy balance closure at many fluxnet locations. Data quality is often evaluated by comparing total available energy, composed of net radiation (Rn) and G, to the sum of latent (LE) and sensible (H) heat fluxes as measured by eddy covariance. Unfortunately, G often receives minimal attention during an experiment because other flux terms (e.g., Rn and LE) are larger or require more complex instrumentation. However, G at certain time periods can account for 10 to 30 percent of Rn, especially beneath short vegetation. Thus, errors in G can confound energy closure tests and lead to erroneous conclusions about of eddy covariance performance. Research was conducted to evaluate difference methods for automating and improving measurements of G. Automated soil heat capacity sensors were combined with heat flux plates to measure conduction and changes in heat storage at different position in the soil profile. The heat capacity sensors were also used to measure soil water content and soil temperature. Data were collected beneath turfgrass, a tallgrass prairie and a juniperous forest. Field results and numerical models were used to study the best sensor configuration and data analysis algorithms. Practical guidelines for measuring and calculating soil heat flux will be presented.

Ham, J. M.

2001-12-01

150

Uncertainties Associated with Flux Measurements Due to Heterogeneous Contaminant Distributions  

EPA Science Inventory

Mass flux and mass discharge measurements at contaminated sites have been applied to assist with remedial management, and can be divided into two broad categories: point-scale measurement techniques and pumping methods. Extrapolation across un-sampled space is necessary when usi...

151

Preliminary measurements of heat flux in a subsonic gun simulator  

Microsoft Academic Search

Preliminary measurements of heat flux have been obtained in a subsonic gun simulator with thin film resistance thermometry for an inert, single phase flow expanding behind a projectile from an initial pressure of 8 bars and resulting in an exit projectile velocity of 40 m\\/s. The results show that heat transfer measurements at locations swept by the projectile are possible

A. F. Bicen; M. Schmidt; J. H. Whitelaw

1987-01-01

152

Measurement of a surface heat flux and temperature  

Microsoft Academic Search

The Heat Flux Microsensor is a new sensor which was recently patented by Virginia Tech and is just starting to be marketed by Vatell Corp. The sensor is made using the thin-film microfabrication techniques directly on the material that is to be measured. It consists of several thin-film layers forming a differential thermopile across a thermal resistance layer. The measured

R. M. Davis; G. J. Antoine; T. E. Diller; A. L. Wicks

1994-01-01

153

Direct Measurement of Turbulent Particle and Gas Fluxes by Eddy Covariance Technique  

NASA Astrophysics Data System (ADS)

Direct Measurement of Turbulent Particle and Gas Fluxes by Eddy Covariance Technique Fumiyoshi KONDO (The University of Tokyo) Frank GRIESSBAUM (Universität Münster) Osamu TSUKAMOTO (Okayama University) Mitsuo UEMATSU (The University of Tokyo) The oceans play major key roles in global energy transport, element cycles, and atmospheric radiation balance. The study of the processes at the interface of ocean and atmosphere is essential to develop profound understanding of the mechanisms driving ocean-atmosphere interaction and climate. Eddy covariance technique is the only direct measurement of air-sea particle and gas fluxes. This technique has little assumption (constant flux layer and steady state), and may evaluate small spatial and temporal particle and gas fluxes. For these reasons, we hope that the eddy covariance technique investigates uncertain processes that control the air-sea particle (aerosol) and gas (CO2) fluxes. The understanding of processes controlling both the CO2 uptake to the ocean and the oceans as major source of aerosols is vital for quantifying the role of the global oceans in the climate system. We developed the simultaneous measurement system of turbulent particle and gas fluxes by eddy covariance technique and installed with ship motion correction system on the top of the foremast of R/V Hakuho-Maru and Mirai. The turbulent flux system on the top of the foremast consisted of a sonic anemometer-thermometer (Gill, HS-50), an infrared CO2/H2O gas analyzer (LI-COR, LI-7500), a water-based condensation particle counter (TSI, WCPC3785), and Fog Monitor (Droplet Measurement, FM-100). The ship motion correction system consisted of a three-axis accelerometer and a three-axis rate gyro (Systron Donner, MotionPak II). The sonic anemometer measures three-dimensional wind components relative to the ship including apparent wind velocity due to the ship motion. Then, the ship motion correction system measures the ship motions by time integral of accelerometer and rate gyro. The turbulent flux system on the top of the foremast is capable to simultaneously measure the turbulent flux of the CO2 and H2O gases, fine aerosols (5 nm - 3 ?m diameters), and fog water droplets (2 ?m - 50 ?m diameters). Analog and digital output signals from both systems are sampled at 10 Hz by a PC-based data logging systems. In this study, we will present the direct flux measurement system and discuss results of air-sea particle and CO2 fluxes directly evaluated by the eddy covariance technique over the open ocean.

Kondo, F.; Griessbaum, F.; Tsukamoto, O.; Uematsu, M.

2010-12-01

154

Intercomparison of gas analyzers for methane flux measurements  

NASA Astrophysics Data System (ADS)

Four gas analyzers, capable of measuring methane concentration at a response time necessary for eddy covariance flux measurements, were operated in parallel for about six months between March and August 2010. Their reliability, need of maintenance, user friendliness, data coverage, and data quality were evaluated. The primary aim of this campaign was to provide an instrumentation suggestion for the European Research Infrastructure ICOS (Integrated Carbon Observation System). The instruments used were TGA100A (Campbell Scientific Inc.), RMT-200 (Los Gatos Research Inc.) , G1301-f (Picarro Inc.), and LI-7700 (Li-Cor Inc.). The last one, LI-7700, was a prototype of a later commercialized open path analyzer. The other instruments were closed path analyzers. The measurement site is an oligotrophic open fen Siikaneva, located in southern Finland. The site provides spatially quite uniform methane flux within the footprint. The methane flux rises in the spring, peaks in early August and falls down during the autumn. This provides excellent opportunity to study the performance of the analyzers at different CH4 flux levels from near zero up to about 5 mg m-2 h-1. The preliminary results show great similarity among the instruments in both concentrations and fluxes. Detailed numbers of the measurement characteristics will be provided later. The reliability and need of maintenance are difficult to evaluate quantitatively during that short period.

Haapanala, S.; Rinne, J.; Vesala, T.

2010-12-01

155

A new low-power, open-path instrument for measuring methane flux by eddy covariance  

NASA Astrophysics Data System (ADS)

This paper describes a new low-power instrument for measuring methane flux by eddy covariance method at sites without grid power. Design and field performance of the LI-7700 Methane Analyzer (LI-COR Biosciences) are examined in this study. The instrument uses 8 W of power in steady-state operation and employs a tunable diode laser in an open Herriott cell configuration with 0.47 m base path and 30 m optical path length. Methane number density is measured using wavelength modulation spectroscopy (WMS) with 2f detection. Typical signal noise is <5 ppb rms at 10 Hz. Corrections for variations in temperature, pressure and water vapor are described. Data losses due to mirror contamination and condensation are minimized by a radiation shield and automatic mirror cleaning system and are shown to be small. Measured spectra and co-spectra are shown to follow the Kaimal model at deployment sites meeting classical criteria, and to follow sensible heat flux co-spectra from the sonic anemometer in most other cases, including difficult ones. Measured fluxes are similar in magnitude to those expected from the literature, and zero flux was measured during both summer and winter at a site known to have fluxes at or very near zero.

McDermitt, D.; Burba, G.; Xu, L.; Anderson, T.; Komissarov, A.; Riensche, B.; Schedlbauer, J.; Starr, G.; Zona, D.; Oechel, W.; Oberbauer, S.; Hastings, S.

2011-02-01

156

Uncertainty of calorimeter measurements at NREL's high flux solar furnace  

SciTech Connect

The uncertainties of the calorimeter and concentration measurements at the High Flux Solar Furnace (HFSF) at the National Renewable Energy Laboratory (NREL) are discussed. Two calorimeter types have been used to date. One is an array of seven commercially available circular foil calorimeters (gardon or heat flux gages) for primary concentrator peak flux (up to 250 W/cm{sup 2}). The second is a cold-water calorimeter designed and built by the University of Chicago to measure the average exit power of the reflective compound parabolic secondary concentrator used at the HFSF (over 3.3 kW across a 1.6cm{sup {minus}2} exit aperture, corresponding to a flux of about 2 kW/cm{sup 2}). This paper discussed the uncertainties of the calorimeter and pyrheliometer measurements and resulting concentration calculations. The measurement uncertainty analysis is performed according to the ASME/ANSI standard PTC 19.1 (1985). Random and bias errors for each portion of the measurement are analyzed. The results show that as either the power or the flux is reduced, the uncertainties increase. Another calorimeter is being designed for a new, refractive secondary which will use a refractive material to produce a higher average flux (5 kW/cm{sup 2}) than the reflective secondary. The new calorimeter will use a time derivative of the fluid temperature as a key measurement of the average power out of the secondary. A description of this calorimeter and test procedure is also presented, along with a pre-test estimate of major sources of uncertainty. 8 refs., 4 figs., 3 tabs.

Bingham, C.E.

1991-12-01

157

Comparison between elementary flux modes analysis and 13C-metabolic fluxes measured in bacterial and plant cells  

PubMed Central

Background 13C metabolic flux analysis is one of the pertinent ways to compare two or more physiological states. From a more theoretical standpoint, the structural properties of metabolic networks can be analysed to explore feasible metabolic behaviours and to define the boundaries of steady state flux distributions. Elementary flux mode analysis is one of the most efficient methods for performing this analysis. In this context, recent approaches have tended to compare experimental flux measurements with topological network analysis. Results Metabolic networks describing the main pathways of central carbon metabolism were set up for a bacteria species (Corynebacterium glutamicum) and a plant species (Brassica napus) for which experimental flux maps were available. The structural properties of each network were then studied using the concept of elementary flux modes. To do this, coefficients of flux efficiency were calculated for each reaction within the networks by using selected sets of elementary flux modes. Then the relative differences - reflecting the change of substrate i.e. a sugar source for C. glutamicum and a nitrogen source for B. napus - of both flux efficiency and flux measured experimentally were compared. For both organisms, there is a clear relationship between these parameters, thus indicating that the network structure described by the elementary flux modes had captured a significant part of the metabolic activity in both biological systems. In B. napus, the extension of the elementary flux mode analysis to an enlarged metabolic network still resulted in a clear relationship between the change in the coefficients and that of the measured fluxes. Nevertheless, the limitations of the method to fit some particular fluxes are discussed. Conclusion This consistency between EFM analysis and experimental flux measurements, validated on two metabolic systems allows us to conclude that elementary flux mode analysis could be a useful tool to complement 13C metabolic flux analysis, by allowing the prediction of changes in internal fluxes before carbon labelling experiments.

2011-01-01

158

Modeling variabilty in radiative fluxes on snow surfaces beneath coniferous canopies  

Technology Transfer Automated Retrieval System (TEKTRAN)

Absorption, scattering and emission of solar and thermal radiation by coniferous canopies can have a large influence on the surface energy balance of snow in forests. The high variability of radiative fluxes in sparse or discontinuous forests cannot be captured by simple two-stream canopy radiation...

159

An iterative procedure for estimating areally averaged heat flux using planetary boundary layer mixed layer height and locally measured heat flux  

SciTech Connect

Measurements at the central facility of the Southern Great Plains (SGP) Cloud and Radiation Testbed (CART) are intended to verify, improve, and develop parameterizations in radiative flux models that are subsequently used in General Circulation Models (GCMs). The reliability of this approach depends upon the representativeness of the local measurements at the central facility for the site as a whole or on how these measurements can be interpreted so as to accurately represent increasingly large scales. The variation of surface energy budget terms over the SGP CART site is extremely large. Surface layer measurements of the sensible heat flux (H) often vary by a factor of 2 or more at the CART site (Coulter et al. 1996). The Planetary Boundary Layer (PBL) effectively integrates the local inputs across large scales; because the mixed layer height (h) is principally driven by H, it can, in principal, be used for estimates of surface heat flux over scales on the order of tens of kilometers. By combining measurements of h from radiosondes or radar wind profiles with a one-dimensional model of mixed layer height, they are investigating the ability of diagnosing large-scale heat fluxes. The authors have developed a procedure using the model described by Boers et al. (1984) to investigate the effect of changes in surface sensible heat flux on the mixed layer height. The objective of the study is to invert the sense of the model.

Coulter, R. L.; Gao, W.; Lesht, B. M.

2000-04-04

160

Measurement of Decoherence Time in a Flux Qubit  

NASA Astrophysics Data System (ADS)

We present a measurement of the relaxation and the dephasing times in a flux qubit. In order to improve coherence of the qubit, two external parameters were optimized: the applied flux through the qubit loop and the bias current of the SQUID which serves as a readout device of the qubit state. At the optimal point the dephasing time measured with spin-echo technique was twice longer than the energy relaxation time. By changing one of the two bias parameters while keeping the other at the optimal value, one can separate the contribution of the noise in each parameter to the decoherence of the qubit.

Harrabi, K.; Yoshihara, F.; Nakamura, Y.; Tsai, J. S.

2006-09-01

161

Early forecast of radiation-hazardous solar cosmic ray fluxes on the neutron monitors data  

NASA Astrophysics Data System (ADS)

The system of the early forecast of radiation hazardous fluxes of solar cosmic rays in space on the basis of the real time neutron monitors data obtained by the NMDB (Neutron Monitor Data Base) network is created. The forecast system is based on a short cut technique of definition of a spectrum of solar protons from the data of the limited number of neutron monitor stations and with a simplified procedure of accounts. It is shown that the results of computations of solar proton spectra with the short-cut technique little differ from spectra obtained with a complete technique at energies less than 5 GeV. Thus the good agreement between derived from the neutron monitor data intensities of solar protons in an energy range of hundreds MeV with the data of direct measurements of solar protons at GOES-11 spacecraft is observed. The maximum of increase on neutron monitors outstrips on several hours (2-10) an appropriate maximum of radiation-dangerous fluxes, registered by spacecrafts of GOES series. Thus, the forecast of radiation hazard on the data of neutron monitors is carried out. As demonstrating examples the results of the analysis of ground level enhancement (GLE) events: 23.10, 2.11, 2003, 20.01.2005, and 13.12.2006 are considered.

Vashenyuk, Eduard; Balabin, Yury; Gvozdevsky, Boris

162

Absolute flux measurement at HIGS using Compton backscattering  

NASA Astrophysics Data System (ADS)

The High Intensity ?-ray Source (HI?S) at FELL/TUNL is developing a program to study many aspects of nuclear physics presently using 2-to-50 MeV ?-rays. In many cases these experiments require absolute ?-flux monitoring and determination. This project presents a technique to indirectly measure the absolute ?-ray flux by placing a thin scattering foil in the ?-beam and then detecting the Compton-scattered ?-rays at a particular scattering angle using a HPGe detector. The fluxes of these Compton-scattered ?-rays are low (i.e., 10^3 ?/s) in comparison to the direct flux of the beam ( ˜10^6 ?/s). In addition the Compton-scattered energies are in the energy range of 2 to 5 MeV for ?-ray beam energies below 10 MeV, which are relatively easy to measure with a HPGe detector with very high energy resolution. Recent experimental results from the flux measurements at HI?S will be presented.

Fallin, B.; Ahmed, M. W.; Perdue, B.; Sabourov, A.; Sheard, T.; Tornow, W.; Tonchev, A. P.; Weller, H. R.; Li, J.; Pinaev, I. V.; Wu, Y.; Prior, R. M.; Spraker, M.; Chen, J.; Feldman, G.

2003-10-01

163

Features of the flux of gamma-radiation in the lower atmosphere during precipitation  

NASA Astrophysics Data System (ADS)

We are carrying out observations and studies of increases of gamma radiation intensity in a ground atmosphere layer during precipitations. Measurements have been carried out in two high-altitude points: Apatity (Murmansk) and Barentsburg (Spitsbergen). Scintillation detectors on the basis of NaI(Tl) crystals are used. Continuous radiation detection is made as the count rate in integral channels with threshold values >20 keV, >100 keV. There are more than 500 events of increase in gamma-ray background during precipitation. Average profiles of X-ray radiation increases in a ground level and the related with them increases of intensity of precipitations for stations in Apatity and Barentsburg have been built up. In Apatity the average increase profile in the gamma-ray flux and accompanying with profile of precipitations rate have been obtained. A time gap between peaks of precipitation and increase one is 30-40 minutes. A barometric coefficient of each component of radiation has been calculated. The barometric coefficient has a zero value on gamma-ray. The charged component of the secondary cosmic rays has a typical value ~0.18 %/mB. The lack of the barometric effect on gamma-ray indicates on the local origin of this radiation.

Germanenko, A. V.; Balabin, Yu V.; Gvozdevsky, B. B.; Vashenyuk, E. V.

2013-02-01

164

Distributed Temperature Sensing as a tool for measuring soil heat flux  

NASA Astrophysics Data System (ADS)

Soil heat flux is an important component of the surface energy balance. It is typically measured at a point using heat flux plates. Spatial patterns as well as temporal variability can be measured using Distributed Temperature Sensing (DTS), in which fiber-optic cable is used as an environmental temperature sensor. Previous research has demonstrated that DTS can be used to monitor soil moisture patterns and soil thermal profiles. By using a custom-built mole-plow, fiber optic cables were installed at three depths within the top 15 centimeters of a grass plot in Delft, The Netherlands. DTS was used to measure temperatures along the cable with a spatial resolution of 1 meter and a temporal resolution 5 minutes along a cable of 84 meters length. In this cable the response of soil temperature to the diurnal cycle of net radiation was measured over three months (Passive DTS). By inverse modeling of the diffusion equation, thermal properties of the soil are determined from which soil heat flux is calculated. During several more intensive campaigns, active heating experiments (Active DTS) were also carried out. In this case, a controlled electrical pulse was applied to the stainless steel armoring on the cable. The thermal response of the cable is measured for pulses of different input power, and this is related to the thermal properties of the surrounding soil. Net radiation, thermal conductivity and sensible heat flux were also measured to quantify the surface energy balance during the intensive campaigns. Results will be presented to illustrate that DTS (Active and/or Passive) is a promising and relatively inexpensive tool to measure large scale spatial patterns in temperature, soil moisture and soil heat flux at high spatial and temporal resolution.

Jansen, J.; Steele-Dunne, S. C.; Van De Giesen, N.; Selker, J. S.

2011-12-01

165

Measurement of the cosmic-ray antiproton flux and a search for an antihelium  

Microsoft Academic Search

A balloon-borne instrument has measured the cosmic-ray antiproton flux between 130 and 320 MeV and searched for antihelium between 130 and 370 MeV per nuclear. These particles were selected from the background of normal-matter cosmic rays by combining a selective trigger with a detailed spark chamber visualization of each recorded event. Antiprotons are identified by their characteristic annihilatin radiation. Residue

A. Buffington; S. M. Schindler; C. R. Pennypacker

1981-01-01

166

A PROBLEM WITH FLUX CHAMBER MEASUREMENTS OF BIOGENIC SULFUR EMISSIONS  

EPA Science Inventory

Problems associated with identifying and quantifying factors that influence liquid-phase controlled evolution of hydrogen sulfide and organic sulfides through the air-water interface are briefly reviewed. It was found that at present flux chamber measurements of the release of th...

167

TECHNIQUE FOR GROSS FLUX MEASUREMENTS IN THE OMR CRITICAL ASSEMBLY  

Microsoft Academic Search

A technique was developed for measuring the gross neutron flux ; distributions in the OMR Critical Assembly using Mn-alloy wires. Manganese-alloy ; (Mn-20% cu - l9%Ni) wire segments, one-half inch long, are loaded into Al or Cd ; tubing, which is then placed in a stainless steel tube inserted in the desired ; location in the critical assembly. After irradiation,

Tuttle

1959-01-01

168

Corer–Reactors for Contaminant Flux Measurement in Sediments  

Microsoft Academic Search

disturbance to the sediment. This apparatus has been used in our laboratory for a number of years (Jones and Design details and operating instructions are provided for a sedi- Jung, 1996; Jung et al., 1997) and has generated useful ment corer that can be converted into a reactor for the measurement of the fluxes of contaminants from sediments to overlying

R. F. Jung; D. R. Jones; G. E. Batley

2003-01-01

169

Remote measurement of energy and carbon flux from wildfires in ...  

Treesearch

... Photo and Video Gallery, Publications, Recreational Activities, Research and ... Description: Temperature, intensity, spread, and dimensions of fires burning in ... first in situ airborne measurements of sensible heat and carbon fluxes in fire plumes ... These estimators provide a means to determine rates of fuel consumption ...

170

Preliminary Measurements of Heat Flux in a Subsonic Gun Simulator.  

National Technical Information Service (NTIS)

Preliminary measurements of heat flux have been obtained in a subsonic gun simulator with thin film resistance thermometry for an inert, single phase flow expanding behind a projectile from an initial pressure of 8 bars and resulting in an exit projectile...

A. F. Bicen M. Schmidt J. H. Whitelaw

1987-01-01

171

Estimation of wet surface evaporation from sensible heat flux measurements  

Microsoft Academic Search

A new method is proposed to estimate wet surface evaporation by means of measurements of sensible heat flux and of air temperature, relative humidity, and wind speed at one level only. This formulation is made possible by the linearization of the Bowen ratio, a common assumption in other methods, such as Penman's model and its derivatives. The method will be

Nikki Vercauteren; Elie Bou-Zeid; Hendrik Huwald; Marc B. Parlange; Wilfried Brutsaert

2009-01-01

172

Measurement of a Surface Heat Flux and Temperature.  

National Technical Information Service (NTIS)

The Heat Flux Microsensor is a new sensor which was recently patented by Virginia Tech and is just starting to be marketed by Vatell Corp. The sensor is made using the thin-film microfabrication techniques directly on the material that is to be measured. ...

R. M. Davis G. J. Antoine T. E. Diller A. L. Wicks

1994-01-01

173

Single-cell flux measurement by continuous fluorescence microphotolysis  

Microsoft Academic Search

Continuous fluorescence microphotolysis (CFM) was adapted to flux measurements in single cells. The principle of the method is simple: Cells are equilibrated with a fluorescent solute, an individual cell is continuously irradiated by a laser beam focussed down to approximately the diameter of the cell, and fluorescence originating from the irradiated cell is monitored. In this procedure irradiation irreversibly photolyzes

M. Scholz; K. Schulten; R. Peters

1985-01-01

174

Radio Sources: 3.3mm Flux and Variability Measurements.  

National Technical Information Service (NTIS)

Graphical and tabular summaries of 3.3-mm (90-GHz) flux measurements of 35 discrete galactic and extragalactic sources are presented, including results of extensive monitoring of nine sources. Variability at 3.3-mm is certain for NGC 1068, NGC 1275, 3C120...

E. E. Epstein J. W. Montgomery M. M. Dworetsky W. G. Fogarty

1971-01-01

175

Determination of persistence effects in spatio-temporal patterns of upward long-wave radiation flux density from an urban courtyard by means of Time-Sequential Thermography  

Microsoft Academic Search

This research analyses upward long-wave radiation flux density from urban surfaces using a high-resolution thermal-infrared (TIR) camera and meteorological measurements in the city of Berlin, Germany. We report spatio-temporal patterns of the difference between upward long-wave radiation flux density from courtyard surfaces and the roof. For temporal analysis, the TIR camera recorded one TIR image per minute over a period

Fred Meier; Dieter Scherer; Jochen Richters

2010-01-01

176

A Model of the Starfish Flux in the Inner Radiation Zone.  

National Technical Information Service (NTIS)

A model of the Starfish electrons injected into the radiation belt in July 1962 was determined for epoch Septmeber 1964. This model distinguishes between artificial and natural electrons and provides the artificial unidirectional electron flux as a functi...

E. G. Stassinopoulos M. J. Teague

1972-01-01

177

A Novel Detector for High Neutron Flux Measurements  

SciTech Connect

Measuring alpha particles from a neutron induced break-up reaction with a mass spectrometer can be an excellent tool for detecting neutrons in a high neutron flux environment. Break-up reactions of {sup 6}Li and {sup 12}C can be used in the detection of slow and fast neutrons, respectively. A high neutron flux detection system that integrates the neutron energy sensitive material and helium mass spectrometer has been developed. The description of the detector configuration is given and it is soon to be tested at iThemba LABS, South Africa.

Singo, T. D.; Wyngaardt, S. M. [Department of Physics, University of Stellenbosch, Private bag X1, Matieland, Stellenbosch (South Africa); Papka, P. [Department of Physics, University of Stellenbosch, Private bag X1, Matieland, Stellenbosch (South Africa); Nuclear Physics group, iThemba labs, P. O. Box 722, Somerset West 7129 (South Africa); Dobson, R. T. [Department of Mechanical and Mechatronic Engineering, University of Stellenbosch, Private bag X1, Matieland, Stellenbosch (South Africa)

2010-01-05

178

Solar cycle variation of trapped proton fluxes measured by LEO satellites.  

NASA Astrophysics Data System (ADS)

Now days there are few models of the Earth radiation belts proton fluxes that are used for prediction of the fluxes at the different orbits of the spacecrafts. Discrepancies in their predictions are wellknown. The AP8 model of trapped proton fluxes is based on the satellite data that were measured 1960th and 1970th during the anomalous weak 20th (in comparison with the 21st and 22d ) solar cycle and solar cycle variation is taken into account only by specifying two different models for solar maximum and solar minimum. The TPM-1 model calculates the proton fluxes for any year of solar activity and contains sub-models for quiet and active states of magnetosphere. Solar cycle variation of trapped protons measured during the 23rd solar cycle on board low orbital polar satellites Coronas-F (500 km altitude) and NPOES-15, -17 (800 km altitude) in 2001 - 2007 is considered in this report. The experimental proton fluxes measured for the drift sells L=1.14-1.2 were compared with the predictions of AP8 model for solar maximum and minimum as well as with the prediction of TPM-1 model.

Nikolaeva, Natalia; Kuznetsov, Nikolay; Panasyuk, Michail

179

MARIE Dose and Flux Measurements in Mars Orbit  

NASA Astrophysics Data System (ADS)

We present results from the Martian Radiation Environment Experiment (MARIE), aboard the 2001 Mars Odyssey spacecraft in orbit around Mars. MARIE operated successfully from March 2002 through October 2003. At the time of this writing, the instrument is off due to a loss of communications during an extremely intense Solar Particle Event. Efforts to revive MARIE are planned for Spring 2004, when Odyssey's role as a communications relay for the MER rovers is completed. During the period of successful operation, MARIE returned the first detailed energetic charged particle data from Mars. Due to limitations of the instrument, normalizing MARIE data to flux or dose is not straightforward - several large corrections are needed. Thus normalized results (like dose or flux) have large uncertainties and/or significant model-dependence. The problems in normalization are mainly due to inefficiency in detecting high-energy protons (signal-to-noise problems force the trigger threshold to be higher than optimal), to the excessively high gains employed in the signal processing electronics (many ions deposit energy sufficient to saturate the electronics, and dE/dx information is lost), and to artifacts associated with the two trigger detectors (incomplete registration of dE/dx). Despite these problems, MARIE is efficient for detecting helium ions with kinetic energies above about 30 MeV/nucleon, and for detecting high-energy ions (energies above about 400 MeV/nucleon) with charges from 5 to 10. Fluxes of these heavier ions can be compared to fluxes obtained from the ACE/CRIS instrument, providing at least one area of direct comparison between data obtained at Earth and at Mars; this analysis will be presented as a work in progress. We will also present dose-rate data, with a detailed explanation of the many sources of uncertainty in normalization. The results for both flux and dose will be compared to predictions of the HZETRN model of the GCR environment.

Zeitlin, C.; Cleghorn, T.; Cucinotta, F.; Saganti, P.; Andersen, V.; Lee, K.; Pinsky, L.; Turner, R.; Atwell, W.

180

Measurements of solar flux density distribution on a plane receiver due to a flat heliostat  

SciTech Connect

An experimental facility is designed and manufactured to measure the solar flux density distribution on a central flat receiver due to a single flat heliostat. The tracking mechanism of the heliostat is controlled by two stepping motors, one for tilt angle control and the other for azimuth angle control. A x-y traversing mechanism is also designed and mounted on a vertical central receiver plane, where the solar flux density is to be measured. A miniature solar sensor is mounted on the platform of the traversing mechanism, where it is used to measure the solar flux density distribution on the receiver surface. The sensor is connected to a data acquisition card in a host computer. The two stepping motors of the heliostat tracking mechanism and the two stepping motors of the traversing mechanism are all connected to a controller card in the same host computer. A software `TOWER` is prepared to let the heliostat track the sun, move the platform of the traversing mechanism to the points of a preselected grid, and to measure the solar flux density distribution on the receiver plane. Measurements are carried out using rectangular flat mirrors of different dimensions at several distances from the central receiver. Two types of images were identified on the receiver plane - namely, apparent (or visible) and mirror-reflected radiation images. Comparison between measurements and a mathematical model validates the mathematical model. 13 refs., 12 figs., 1 tab.

Elsayed, M.M.; Fathalah, K.A.; Al-Rabghi, O.M. [King Abdulaziz Univ., Jeddah (Saudi Arabia)

1995-06-01

181

Spectral line radiation from solar small-scale magnetic flux tubes  

Microsoft Academic Search

We consider spectral line radiation from small-scale magnetic model flux tubes in the solar atmosphere. The structure of the tube is determined from the magnetostatic equations in the thin flux tube approximation. We assume that the tube is in energy equilibrium and pressure balance with the ambient medium. For the latter, we construct a quiet sun model with an artificial

F. Kneer; S. S. Hasan; W. Kalkofen

1996-01-01

182

Preliminary Investigation of Changes in X-Ray Multilayer Optics Subjected to High Radiation Flux.  

National Technical Information Service (NTIS)

A variety of metal multilayers was exposed to high x-ray flux using Sandia National Laboratories' PROTO II machine in the gas puff mode. Fluxes incident on the multilayers above 700 MW/cm exp 2 in total radiation, in nominal 20 ns pulses, were realized. T...

M. P. Hockaday R. L. Blake J. S. Grosso M. M. Selph M. M. Klein

1985-01-01

183

Creation of a child universe by the shell radiating negative energy flux  

NASA Astrophysics Data System (ADS)

One possibility for the creation of a child universe by producing a false vacuum bubble in the laboratory is discussed. We obtain a simple equation of motion of the spherically symmetric thin shell of radiating out-going null energy flux. Analysing the equation, we show that the shell radiates negative energy flux and the false vacuum bubble becomes a child universe in the case of a certain kind of surface stress tensor.

Mishima, Takashi; Suzuki, Hiromi; Yoshino, Noriaki

1997-08-01

184

Radiative cooling of a hot flux tube in the solar photosphere  

Microsoft Academic Search

Radiative energy transport is of key importance for the dynamics of slender magnetic flux tubes in the solar atmosphere, particularly so in connection with the filamentation of the sunspot penumbra. In investigations using the thin-flux-tube approximation of the MHD equations, the radiative exchange with the surrounding atmosphere has hitherto been described by the relaxation-time approach, also called `Newton's law of

R. Schlichenmaier; J. H. M. J. Bruls; M. Schüssler

1999-01-01

185

Ecosystem photosynthesis inferred from measurements of carbonyl sulphide flux  

NASA Astrophysics Data System (ADS)

Limited understanding of carbon dioxide sinks and sources on land is often linked to the inability to distinguish between the carbon dioxide taken up by photosynthesis, and that released by respiration. Carbonyl sulphide, a sulphur-containing analogue of carbon dioxide, is also taken up by plants, and could potentially serve as a powerful proxy for photosynthetic carbon dioxide uptake, which cannot be directly measured above the leaf scale. Indeed, variations in atmospheric concentrations of carbonyl sulphide are closely related to those of carbon dioxide at regional, local and leaf scales. Here, we use eddy covariance and laser spectroscopy to estimate the net exchange of carbon dioxide and carbonyl sulphide across three pine forests, a cotton field and a wheat field in Israel. We estimate gross primary productivity--a measure of ecosystem photosynthesis--directly from the carbonyl sulphide fluxes, and indirectly from carbon dioxide fluxes. The two estimates agree within an error of +/-15%. The ratio of carbonyl sulphide to carbon dioxide flux at the ecosystem scale was consistent with the variability in mixing ratios observed on seasonal timescales in the background atmosphere. We suggest that atmospheric measurements of carbonyl sulphide flux could provide an independent constraint on estimates of gross primary productivity, key to projecting the response of the land biosphere to climate change.

Asaf, David; Rotenberg, Eyal; Tatarinov, Fyodor; Dicken, Uri; Montzka, Stephen A.; Yakir, Dan

2013-03-01

186

Surface Flux Measurements at King Sejong Station in West Antarctica  

NASA Astrophysics Data System (ADS)

The Antarctic Peninsula is important in terms of global warming research due to pronounced increase of air temperature over the last century. The first eddy covariance system was established and turbulent fluxes of heat, water vapor, CO2 and momentum have been measured at King Sejong Station (62 \\deg 13øØS, 58 \\deg 47øØW) located in the northern edge of the Antarctic Peninsula since December in 2002. Our objectives are to better understand the interactions between the Antarctic land surface and the atmosphere and to test the feasibility of the long-term operation of eddy covariance system under extreme weather conditions. Various lichens cover the study area and the dominant species is Usnea fasciata-Himantormia. Based on the analyses on turbulent statistics such as integral turbulence characteristics of vertical velocity (w) and heat (T), stationarity test and investigation of correlation coefficient, they follow the Monin-Obukhov similarity and eddy covariance flux data were reliable. About 50 % of total retrieved sensible heat flux data could be used for further analysis. We will report on seasonal variations of energy and mass fluxes and environmental variables. In addition, factors controlling these fluxes will be presented. Acknowledgement: This study was supported by ¡rEnvironmental Monitoring on Human Impacts at the King Sejong Station, Antarctica¡_ (Project PP04102 of Korea Polar Research Institute) and ¡rEco-technopia 21 project¡_ (Ministry of Environment of Korea).

Choi, T.; Lee, B.; Lee, H.; Shim, J.

2004-12-01

187

Connecting extracellular metabolomic measurements to intracellular flux states in yeast  

PubMed Central

Background Metabolomics has emerged as a powerful tool in the quantitative identification of physiological and disease-induced biological states. Extracellular metabolome or metabolic profiling data, in particular, can provide an insightful view of intracellular physiological states in a noninvasive manner. Results We used an updated genome-scale metabolic network model of Saccharomyces cerevisiae, iMM904, to investigate how changes in the extracellular metabolome can be used to study systemic changes in intracellular metabolic states. The iMM904 metabolic network was reconstructed based on an existing genome-scale network, iND750, and includes 904 genes and 1,412 reactions. The network model was first validated by comparing 2,888 in silico single-gene deletion strain growth phenotype predictions to published experimental data. Extracellular metabolome data measured in response to environmental and genetic perturbations of ammonium assimilation pathways was then integrated with the iMM904 network in the form of relative overflow secretion constraints and a flux sampling approach was used to characterize candidate flux distributions allowed by these constraints. Predicted intracellular flux changes were consistent with published measurements on intracellular metabolite levels and fluxes. Patterns of predicted intracellular flux changes could also be used to correctly identify the regions of the metabolic network that were perturbed. Conclusion Our results indicate that integrating quantitative extracellular metabolomic profiles in a constraint-based framework enables inferring changes in intracellular metabolic flux states. Similar methods could potentially be applied towards analyzing biofluid metabolome variations related to human physiological and disease states.

Mo, Monica L; Palsson, Bernhard ?; Herrgard, Markus J

2009-01-01

188

CERES-derived Surface radiative flux consistent with A-train observations  

NASA Astrophysics Data System (ADS)

Top-of-atmosphere radiative fluxes derived from CERES instruments on Aqua and Terra provide observations to understand earth radiation budget and its variability. Using cloud and aerosol properties derived from MODIS combined with atmospheric thermodynamical properties from reanalysis, surface radiative fluxes are also estimated in the CERES project. Observations from the A-train constellation, such as CALIPSO, CloudSat, and AIRS, are helping to improve the estimate of surface radiative fluxes. For example, the ability of CALIPSO and CloudSat to detect clouds and cloud base height better than MODIS contributes to improve the surface downward longwave flux. The global annual mean cloud fraction derived from CALIPSO and CloudSat is larger them the cloud fraction derived from MODIS by 0.11 (0.04 excluding clouds with optical thickness less than 0.3). The global annual mean cloud base height derived from CALIPSO and CloudSat is lower than that derived from MODIS by an empirical relationship by 1.6 km. As a consequence, the global annual mean surface downward longwave flux increases by 3.4 Wm-2 compared to the value computed with MODIS only. The regional difference is even larger. The increase of the surface downward longwave irradiance in the Arctic exceeds 10 Wm-2 (~4%) in winter because during polar night CALIPSO and CloudSat detect more clouds compared to the cloud amount derived by the CERES cloud algorithm. With these better cloud properties derived from CALIPSO and CloudSat, and temperature and humidity profiles derived from AIRS, the systematic error and uncertainty of inputs used in surface radiative flux computations in CERES processes can be quantified. The systematic error and uncertainty estimates combined with the CERES TOA EBAF product are used to derive improved surface radiative fluxes that are consistent with A-train observations. In this presentation, we will explain how the improved gridded monthly mean surface radiative fluxes (CERES surface EBAF product) are obtained. We will also present an analysis using improved surface radiative fluxes, such as how surface net radiative flux spatially and temporally correlates with TOA net flux and how surface net and atmospheric shortwave and longwave fluxes changes with the ENSO index.

Kato, S.; Loeb, N. G.; Rose, F. G.; Doelling, D.; Rutan, D. A.

2011-12-01

189

Flux measurements of energy and trace gases in urban Houston, Texas  

NASA Astrophysics Data System (ADS)

We describe the setup and some first year results of a new flux measurements tower in an urban area. An existing radio communications tower 4 km north of downtown Houston was equipped with micrometeorological instrumentation and trace gas sampling lines in spring 2007. Wind speed, temperature and relative humidity are recorded at five levels between 12 and 60 m above ground; 3-D wind speed measurements, solar and net radiances, and trace gas sampling are established from the 60 m level. A closed path IRGA is used for CO2 and water vapor fluxes, and independent instrumentation for criteria pollutant and VOC fluxes. Two CSI data loggers and software control the measurements, and EdiRe software is used to analyze turbulence data and compute fluxes. A project description is provided at http://atmo.tamu.edu/yellowcabtower. Surface properties as calculated from the gradient measurements show the site to be surprisingly uniform, with displacement heights between 5 and 9 m and roughness lengths between 0.4 and 0.7 m, despite urban heterogeneity. The latter is investigated through visible/near IR orthoimagery and LIDAR data, which are incorporated into a local GIS. Net radiation was also only marginally affected by surface heterogeneity. At this urban location it is balanced by roughly equal amounts of sensible heat, latent heat, and storage fluxes. Latent heat flux, however, is smaller outside the growing season, with an equivalent increase in winter storage fluxes, as expected. Significant differences are also observed with direction during summer, showing decreased Bowen ratios and lower CO2 emissions from sectors with a larger urban tree canopy cover in the footprint. The largely mature, dominantly oak urban canopy cover alleviates approximately 100 W m- 2 during typical summer days. On the other hand, anthropogenic CO2 emissions dominate over photosynthetic uptake all year round. Measured carbon fluxes peak during morning rush-hour traffic, especially when increasing stretches of the main commuter road fall into the footprint. Outside the rush hour, daytime carbon fluxes typically ranged from 0.4 to 1.6 g C m-2 h-1. A seasonal comparison shows that up to 75% of midday anthropogenic carbon flux is removed via photosynthesis in the dominant wind sector, S, which bears typical tree canopy covers of 25-50% on pervious surfaces.

Boedeker, I.; Schade, G. W.; Adams, S.; Park, C.

2008-12-01

190

Development of Aerosol Models for Radiative Flux Calculations at ARM Sites  

SciTech Connect

The direct radiative forcing (DRF) of aerosols, the change in net radiative flux due to aerosols in non-cloudy conditions, is an essential quantity for understanding the human impact on climate change. Our work has addressed several key issues that determine the accuracy, and identify the uncertainty, with which aerosol DRF can be modeled. These issues include the accuracy of several radiative transfer models when compared to measurements and to each other in a highly controlled closure study using data from the ARM 2003 Aerosol IOP. The primary focus of our work has been to determine an accurate approach to assigning aerosol properties appropriate for modeling over averaged periods of time and space that represent the observed regional variability of these properties. We have also undertaken a comprehensive analysis of the aerosol properties that contribute most to uncertainty in modeling aerosol DRF, and under what conditions they contribute the most uncertainty. Quantification of these issues enables the community to better state accuracies of radiative forcing calculations and to concentrate efforts in areas that will decrease uncertainties in these calculations in the future.

Ogren, John A.; Dutton, Ellsworth G.; McComiskey, Allison C.

2006-09-30

191

Intercomparisons of Earth Radiation Budget Experiment (ERBE) Active Cavity Radiometers' Fluxes  

NASA Astrophysics Data System (ADS)

This paper intercompares the radiative flux values determined by four nonscanning active cavity radiometers of the ERBS (Earth Radiation Budget Satellite) spacecraft launched on October 5, 1984 in a non-sun- synchronous trajectory. Two are the total radiometers: the medium field-of-view total (MFOV-T) and the wide field-of-view total (WFOV-T) which measure the radiation fields in the spectral band of 0.2 - 50 ?m and other two are the shortwave radiometers: the medium field-of-view shortwave (MFOV- SW) and the wide field-of- view shortwave (WFOV-SW) which measure the Earth's reflected radiation in the wavelength region of 0.2 - 5.0 ?m. The WFOV (FOV: 142.8°) sees the entire Earth's disk while the MFOV (FOV: 88.4°) sees 10° diameter geocentric latitudinal regions. These radiometers were calibrated continuously by observing the in-flight internal black bodies and the Sun every two weeks. The resulting gains and offsets values found to be very stable and accurate within 0.1%. In this paper, we compare the results obtained by MFOV radiometers with the WFOV measurements, which are widely used by the climate scientists throughout the world. We report the results covering the period from January 1985 through December 1990. The MFOV radiometers degradation was found to be less than 0.5% due to exposure to direct solar radiation. The WFOV radiometers degraded approximately 5% during the same period because of considerably greater solar exposure. In addition, the WFOV measurements were affected by the decreasing spacecraft-earth distance while the MFOV measurements were not affected. The measurements were not corrected for the significant measurements variations caused by the varying inverse spacecraft-earth distance. Therefore, the MFOV measurements represent a better data set to analyze long- term climate variations in the Tropics. The 1985-1999 WFOV measurements were reduced and were made available for climate studies. We believe that the raw 1990-1999 ERBS MFOV radiometric measurements should be reduced and made available for long-term climate studies as well as the 1999-2005 measurements.

Pandey, D. K.; Lee, R. B.

2006-05-01

192

Annual cycle of radiation fluxes over the Arctic ocean: Sensitivity to cloud optical properties  

SciTech Connect

The relationship between cloud optical properties and the radiative fluxes over the Arctic Ocean is explored by conducting a series of modeling experiments. The annual cycle of arctic cloud optical properties that are required to reproduce both the outgoing radiative fluxes at the top of the atmosphere as determined from satellite observations and the available determinations of surface radiative fluxes are derived. Existing data on cloud fraction and cloud microphysical properties are utilized. Four types of cloud are considered: low stratus clouds, midlevel clouds, citrus clouds, and wintertime ice crystal precipitation. Internally consistent annual cycles of surface temperature, surface albedo, cloud fraction and cloud optical properties, components of surface and top of atmosphere radiative fluxes, and cloud radiative forcing are presented. The modeled total cloud optical depth (weighted by cloud fraction) ranges from a low value in winter of 2 to a high summertime value of 8. Infrared emmissivities for liquid water clouds are shown to be substantially less than unity during the cold half of the year. Values of modeled surface cloud radiative forcing are positive except for two weeks in midsummer; over the course of the year clouds have a net warming effect on the surface in the Arctic. Total cloud radiative forcing at the top of the atmosphere is determined to be positive only briefly in early autumn. Surface longwave fluxes are shown to be very sensitive to the presence of lower-tropospheric ice crystal precipitation during the cold half of the year.

Curry, J.A. (Univ. of Colorado, Boulder (United States)); Ebert, E.E. (Bureau of Meteorology Research Centre, Melbourne (Australia))

1992-11-01

193

The Quantitative Interrelationships between Ion Fluxes, Cell Swelling, and Radiation Dose in Ultraviolet Hemolysis  

PubMed Central

Following treatment with ultraviolet radiation, human red cells leak cations at accelerated rates which depend on the radiation dose. With one exception (initial Na efflux), these accelerated cation fluxes fit the Ussing flux-ratio criterion for passive diffusion. Na efflux is transiently high, but with time falls to the value expected on the basis of the other cation fluxes. An equation based on the hypothesis of colloid osmotic hemolysis satisfactorily predicts the rate of cell swelling as a result of these ion movements.

Cook, John S.

1965-01-01

194

Measurement of a surface heat flux and temperature  

NASA Astrophysics Data System (ADS)

The Heat Flux Microsensor is a new sensor which was recently patented by Virginia Tech and is just starting to be marketed by Vatell Corp. The sensor is made using the thin-film microfabrication techniques directly on the material that is to be measured. It consists of several thin-film layers forming a differential thermopile across a thermal resistance layer. The measured heat flux q is proportional to the temperature difference across the resistance layer q= k(sub g)/delta(sub g) x (t(sub 1) - T(sub 2)), where k(sub g) is the thermal conductivity and delta (sub g) is the thickness of the thermal resistance layer. Because the gages are sputter coated directly onto the surface, their total thickness is less than 2 micrometers, which is two orders of magnitude thinner than previous gages. The resulting temperature difference across the thermal resistance layer (delta is less than 1 micrometer) is very small even at high heat fluxes. To generate a measurable signal many thermocouple pairs are put in series to form a differential thermopile. The combination of series thermocouple junctions and thin-film design creates a gage with very attractive characteristics. It is not only physically non-intrusive to the flow, but also causes minimal disruption of the surface temperature. Because it is so thin, the response time is less than 20 microsec. Consequently, the frequency response is flat from 0 to over 50 kHz. Moreover, the signal of the Heat Flux Microsensor is directly proportional to the heat flux. Therefore, it can easily be used in both steady and transient flows, and it measures both the steady and unsteady components of the surface heat flux. A version of the Heat Flux Microsensor has been developed to meet the harsh demands of combustion environments. These gages use platinum and platinum-10 percent rhodium as the thermoelectric materials. The thermal resistance layer is silicon monoxide and a protective coating of Al2O3 is deposited on top of the sensor. The superimposed thin-film pattern of all six layers is presented. The large pads are for connection with pins used to bring the signal out the back of the ceramic. flux measurement, the surface temperature is measured with a platinum resistance layer (RTS). &The resistance of this layer increases with increasing temperature. Therefore, these gages simultaneously measure the surface temperature and heat flux. The demonstrated applications include rocket nozzles, SCRAM jet engines, gas turbine engines, boiling heat transfer, flame experiments, basic fluid heat transfer, hypersonic flight, and shock tube testing. *The laboratory involves using one of these sensors in a small combustion flame. -The sensor is made on a 2.5 cm diameter piece of aluminum nitride ceramic.

Davis, R. M.; Antoine, G. J.; Diller, T. E.; Wicks, A. L.

1994-04-01

195

Magnetic flux emergence in granular convection: radiative MHD simulations and observational signatures  

NASA Astrophysics Data System (ADS)

Aims:We study the emergence of magnetic flux from the near-surface layers of the solar convection zone into the photosphere. Methods: To model magnetic flux emergence, we carried out a set of numerical radiative magnetohydrodynamics simulations. Our simulations take into account the effects of compressibility, energy exchange via radiative transfer, and partial ionization in the equation of state. All these physical ingredients are essential for a proper treatment of the problem. Furthermore, the inclusion of radiative transfer allows us to directly compare the simulation results with actual observations of emerging flux. Results: We find that the interaction between the magnetic flux tube and the external flow field has an important influence on the emergent morphology of the magnetic field. Depending on the initial properties of the flux tube (e.g. field strength, twist, entropy etc.), the emergence process can also modify the local granulation pattern. The emergence of magnetic flux tubes with a flux of 1019 Mx disturbs the granulation and leads to the transient appearance of a dark lane, which is coincident with upflowing material. These results are consistent with observed properties of emerging magnetic flux. Movies are only available in electronic form at http://www.aanda.org

Cheung, M. C. M.; Schüssler, M.; Moreno-Insertis, F.

2007-05-01

196

Solar UV-A and UV-B radiation fluxes at two Alpine stations at different altitudes  

NASA Astrophysics Data System (ADS)

Daily totals of UV-A and UV-B radiation fluxes and global radiation were measured since 1981 at Jungfraujoch (3576 m) a.s.l.) and in Innsbruck (577 m a.s.l.) in their seasonal course. The altitude effect of annual totals yields 19%/1000 m (UV-B), 11%/1000 m (UV-A) and 9%/1000 m (global radiation) with reference to Innsbruck station. The ratio of the daily totals of UV-B/global radiation shows a significant seasonal course with the maximum in summer, whereas the ratio of the daily totals of UV-A/global radiation shows no significant seasonal variation. The biological effective doses of erythema reaction, delayed tanning and immediate tanning by UV-A and UV-B radiant exposure are reported in the seasonal course at Jungfraujoch and in Innsbruck.

Blumthaler, M.; Ambach, W.; Rehwald, W.

1992-03-01

197

Two-flux and diffusion methods for radiative transfer in composite layers  

Microsoft Academic Search

Temperature distributions and heat fluxes are predicted in composite semitransparent layers heated or cooled on both sides by radiation and convection. Two approximate methods were used for performing spectral calculations, and the results were validated by comparison with `exact ` numerical solutions of the radiative transfer equations. The composite layers have refractive indices larger than one, and isotropic scattering is

C. M. Spuckler; R. Siegel

1996-01-01

198

HEO Observations of the Radiation Belt Electron Fluxes: Comparison with Model Predictions and a Source for Model Updates  

NASA Astrophysics Data System (ADS)

We have developed a database of energetic electron fluxes from observations taken by the HEO (94-026 and 97-068) satellites in the inner magnetosphere. The HEO satellites are in highly elliptical orbits, with orbital periods near 12 hours, that cover the L range 2 to 10 for HEO 97-068 and above 3.5 for HEO 94-026. HEO 97-068 covers the same L values at both high (above 2 Re geocentric) and low (below 1.2 Re geocentric) altitudes. Each satellite carries sensors that measure electron and proton fluxes over a wide range of energies. These data have been organized in B, L and MLT using the IGRF and Olsen-Pfizer field models. The database includes the total dose and dose rates observed behind several different shield thickness. The radiation dose measurements are compared to predictions from the current standard models (AE8 and AP8). One and four year average dose measurements indicate that the models over estimate the expected dose by significant factors, especially at shielding levels between 10 and 150 mils Al. The database has been used to study the dynamic response of the radiation belts to magnetic storms and for comparison with observations by other spacecraft. For example, we have compared the electron responses at the same L both at high and low altitudes as a check on the assertion that the radiation belt responses are coherent, i.e. the same at low altitudes as nearer the equator. In particular, we inter-compare the HEO 97-068 high and low altitude fluxes and the SAMPEX low altitude fluxes. We find that the high and low altitude fluxes do indeed track each other quite well with the low altitude 1.5 MeV electron fluxes being about 10 percent of the high altitude fluxes for L = 3 to 6, except during magnetic storm main phase. We have measured the flux decays that relate to the long-term losses following storm-time enhancements. As an example, at L = 3 the high-altitude 1.5 MeV electron fluxes were found to have three distinct 1/e decay times near 5, 10.5 and 17.5 days. These and other results obtained from the database will be presented, summarized and related to ongoing efforts to update the standard models.

Fennell, J. F.; Blake, J. B.; Heynderickx, D.; Crosby, N.

2003-12-01

199

Measurements of the thermal neutrons flux near the EAS core  

NASA Astrophysics Data System (ADS)

The characteristics of the thermal neutrons flux have been measured near the EAS core at the "Carpet-2" EAS array. The thermal neutron detectors were placed on the floor of the tunnel of the Muon Detector (MD) and showers with a core near the MD were selected. Thermal neutrons multiplicity spectrum has been obtained for these showers. Measurements of the lateral distribution function of thermal neutrons at distances of 1-16 m from the shower axis have been performed. The mean number of the recorded thermal neutrons as a function of the number of hadrons crossing the MD has been measured.

Dzhappuev, D. D.; Volchenko, V. I.; Kudzhaev, A. U.; Mikhailova, O. I.; Petkov, V. B.; Stenkin, Yu V.; Tsyabuk, A. L.

2013-02-01

200

Estimating terrestrial uranium and thorium by antineutrino flux measurements.  

PubMed

Uranium and thorium within the Earth produce a major portion of terrestrial heat along with a measurable flux of electron antineutrinos. These elements are key components in geophysical and geochemical models. Their quantity and distribution drive the dynamics, define the thermal history, and are a consequence of the differentiation of the Earth. Knowledge of uranium and thorium concentrations in geological reservoirs relies largely on geochemical model calculations. This article describes the methods and criteria to experimentally determine average concentrations of uranium and thorium in the continental crust and in the mantle by using site-specific measurements of the terrestrial antineutrino flux. Optimal, model-independent determinations involve significant exposures of antineutrino detectors remote from nuclear reactors at both a midcontinental and a midoceanic site. This would require major, new antineutrino detection projects. The results of such projects could yield a greatly improved understanding of the deep interior of the Earth. PMID:18172211

Dye, Stephen T; Guillian, Eugene H

2008-01-02

201

DIRECT MEASUREMENT OF HEAT FLUX FROM COOLING LAKE THERMAL IMAGERY  

SciTech Connect

Laboratory experiments show a linear relationship between the total heat flux from a water surface to air and the standard deviation of the surface temperature field, {sigma}, derived from thermal images of the water surface over a range of heat fluxes from 400 to 1800 Wm{sup -2}. Thermal imagery and surface data were collected at two power plant cooling lakes to determine if the laboratory relationship between heat flux and {sigma} exists in large heated bodies of water. The heat fluxes computed from the cooling lake data range from 200 to 1400 Wm{sup -2}. The linear relationship between {sigma} and Q is evident in the cooling lake data, but it is necessary to apply band pass filtering to the thermal imagery to remove camera artifacts and non-convective thermal gradients. The correlation between {sigma} and Q is improved if a correction to the measured {sigma} is made that accounts for wind speed effects on the thermal convection. Based on more than a thousand cooling lake images, the correlation coefficients between {sigma} and Q ranged from about 0.8 to 0.9.

Garrett, A; Eliel Villa-Aleman, E; Robert Kurzeja, R; Malcolm Pendergast, M; Timothy Brown, T; Saleem Salaymeh, S

2007-12-19

202

Initial Tile Temperature and Heat Flux Measurements in NSTX  

NASA Astrophysics Data System (ADS)

Due to their compact nature, spherical tori are projected to experience higher peak heat flux than conventional aspect ratio tokamaks of comparable heating power. For NSTX, it has been predicted[1,2] that the peak heat flux in double-null divertor configuration could reach between 10-15 MW/m2, and single-null operation would result in even higher peak heat flux. To test these predictions and support physics operations, two infrared television cameras (Inframetrics 525) have been installed on NSTX to monitor real-time tile heating and surface heat flux. The data are analyzed in real-time with a frame grabber (IMAXX) and software, and these data are also archived on videotape for future analysis. The first set of measurements will focus on thermal emission from the RF antenna, the center stack, and divertor regions. Initial data and comparison with the earlier predictions will be presented. 1 R.Maingi, et. al., "Estimates of Scrape-Off Layer and Divertor Parameters in NSTX", Proc. 1996 Int’l Workshop on the Spherical Torus, Abingdon, U.K., Dec. 4-6, 1996. 2 R. Maingi, et. al., "2-D Edge Plasma Transport Calculations for NSTX", Proc. 1997 Int’l Workshop on the Spherical Torus, St. Petersburg, Russia, Sept. 3-5, 1997.

Maingi, Rajesh; Kugel, Henry; Roquemore, Lane; Lasnier, Charles; Johnson, Dave

1999-11-01

203

Observation and simulation of dust aerosol cycle and impact on radiative fluxes during the FENNEC campaign in summer 2011  

NASA Astrophysics Data System (ADS)

The Sahara desert is one of the principal worldwide sources of dust aerosol emissions that play significant role in the climatic system. In the framework of the FENNEC campaign, conducted during the summer 2011, we focus on dust radiative effect and impact on the atmospheric dynamics and profile structure. We study the variability of the measured radiative parameters and model atmospheric dynamics during dust plume observations at the FENNEC sites, therefore, trying to understand the link between the Saharan heat low system and dust aerosols. Due to its large size the airborne dust can absorb and scatter not only solar, but also thermal infrared radiation, which requires consideration of both spectral ranges. Analysis of AERONET and other optical observations during the period of intensive campaign in summer 2011 provides information on variability of aerosol optical characteristics and perturbation of solar and TIR flux. We use these observations in conjunction with the meso-scale model RAMS to understand the impact of the dust plumes on the atmospheric dynamics. We also simulate the dust cycle in order to find the contribution of the different emission sources and identify structure of transport over an extended domain. Then, coupling the radiative code (GAME) we calculate the radiative forcing of dust and compare it to the radiative flux observed and computed based on the AERONET observations. Validation of simulations is made using measurements from space-borne CALIOP lidar, SEVIRI and OMI satellites, AERONET ground-based stations and observations acquired onboard the SAFIRE Falcon 20 research aircraft.

Minvielle, Fanny; Derimian, Yevgeny; Pere, Jean-Christophe; Flamant, Cyrille; Brogniez, Gérard

2013-04-01

204

Radioastronomical measurement of ultrahigh-energy cosmic particle fluxes  

NASA Astrophysics Data System (ADS)

The basic principles underlying the radio telescope measurement of ultrahigh-energy particle fluxes are reviewed. Experimental lunar regolith emission data are presented for the 10^{20} eV energy range. Some conclusions from theoretical work are discussed, as is the influence of a number of factors on the intensity of the radio pulse due to the cascade disk under the Moon's surface.

Filonenko, A. D.

2012-08-01

205

Identifying Loss Mechanisms Responsible for the Rapid Depletion of Outer Radiation Belt Electron Flux  

NASA Astrophysics Data System (ADS)

Since the discovery of earth's radiation belts researchers have sought to explain and predict the changing relativistic electron flux levels in the outer belt. This goal has proved a perplexing challenge because, surprisingly, flux levels do not always rise as energy input from the solar wind increases during active periods such as geomagnetic storms [Reeves et al., 2003;O'Brien et al., 2001]. The erratic response of the radiation belt electrons to geomagnetic activity suggests that flux levels are set by a teetering struggle between acceleration and loss. Thus, to predict flux variations, both processes must be understood. Some acceleration mechanisms have been proposed and tested resulting in incremental progress, but still little is known about how relativistic electrons are removed from the magnetosphere. We investigate how relativistic electrons are lost from the outer radiation belt using a superposed epoch analysis of electron flux decrease events identified in multi-satellite data [Onsager et al., 2002; Green et al., 2004]. More specifically, we test three mechanisms proposed to explain the flux reductions: adiabatic motion in response to a changing magnetic field topology, drift out the magnetopause boundary, and scattering into the atmosphere. The superposed study shows that the magnetic field becomes temporarily stretched at dusk suggesting that adiabatic electron motion might contribute to the initial flux reduction; however, the electron flux does not recover when the magnetic field recovers, indicating that true loss from the magnetosphere occurs. Magnetopause encounters should similarly affect both high energy protons and electrons; however, no concurrent reduction of proton flux is observed implying that this mechanism is not active. Low altitude observations show increased electron flux in the loss cone suggesting that scattering to the atmosphere is the cause the flux depletions. We investigate possible causes of the increased scattering including current sheet scattering and wave particle interactions.

Green, J. C.; Onsager, T. G.; O'Brien, T.; Fraser, B. J.

2004-12-01

206

Light Flux Density Threshold at Which Protein Denaturation is Induced by Synchrotron Radiation Circula Dichroism Beamlines  

SciTech Connect

New high-flux synchrotron radiation circular dichroism (SRCD) beamlines are providing important information for structural biology, but can potentially cause denaturation of the protein samples under investigation. This effect has been studied at the new CD1 dedicated SRCD beamline at ISA in Denmark, where radiation-induced thermal damage effects were observed, depending not only on the radiation flux but also on the focal spot size of the light. Comparisons with similar studies at other SRCD facilities worldwide has lead to the estimation of a flux density threshold under which SRCD beamlines should be operated when samples are to be exposed to low-wavelength vacuum ultraviolet radiation for extended periods of time.

Miles,A.; Janes, R.; Brown, A.; Clarke, D.; Sutherland, J.; Tao, Y.; Wallace, B.; Hoffmann, S.

2008-01-01

207

Grasland Stable Isotope Flux Measurements: Three Isotopomers of Carbon Dioxide Measured by QCL Spectroscopy  

Microsoft Academic Search

To improve our understanding of greenhouse gas dynamics of managed ecosystems such as grasslands, we not only need to investigate the effects of management (e.g., grass cuts) and weather events (e.g., rainy days) on carbon dioxide fluxes, but also need to increase the time resolution of our measurements. Thus, for the first time, we assessed respiration and assimilation fluxes with

M. J. Zeeman; B. Tuzson; W. Eugster; R. A. Werner; N. Buchmann; L. Emmenegger

2007-01-01

208

Developing Consistent Earth System Data Records for the Global Terrestrial Water Cycle: Focus on Shortwave and Longwave Radiative Fluxes  

NASA Astrophysics Data System (ADS)

The overall goal of this MEaSUREs Project is to develop consistent, long-term Earth System Data Records (ESDRs) for the major components of the terrestrial water cycle at a spatial resolution of 0.5 degree at climatic time scale. The shortwave (SW) and longwave (LW) radiative fluxes at the Earth's surface determine the exchange of energy between the land and the atmosphere and consequently, control the hydrologic cycle. Environmental satellites are considered as useful tools for providing information on surface radiative fluxes at various temporal and spatial scales, allowing improvement in estimation of terrestrial water and energy storage and oceanic heat fluxes. During the last two decades, significant progress has been made in assessing the Earth Radiation Balance from satellite observations. Yet, at present, satellite based estimates differ from each other and long term observations at global scale are not readily available. There is a need to utilize existing records of satellite observations and to improve currently available estimates. This requires updates to inference schemes so that new knowledge and most recent auxiliary information can be fully utilized. This paper reports on improvements introduced to an existing methodology to estimate shortwave (SW) radiative fluxes within the atmospheric system, on the development of a new inference scheme for deriving LW fluxes, the implementation of the approach with the ISCCP DX observations and improved atmospheric inputs for the period of 1983-2007, evaluation against ground observations, and comparison with independent satellite methods and numerical models. The resulting ESDRs from the entire MEaSUREs Project are intended to provide a consistent basis for estimating the mean state and variability of the land surface water cycle at a spatial scale relevant to major global river basins. Supported under NASA Grant NNX08AN40A, NRA/Research Opportunities in Space and Earth Sciences-2006.

Pinker, R. T.; Ma, Y.; Nussbaumer, E.

2011-12-01

209

Boundary-layer measurements and surface fluxes in Arctic at the Eureka (Canada) and Tiksi (Russia) climate observatories  

NASA Astrophysics Data System (ADS)

This study focuses on variability of turbulent surface fluxes based on measurements made at two different sites located near the coast of the Arctic Ocean at Eureka (Canadian territory of Nunavut) and Tiksi (East Siberia). Turbulent fluxes and mean meteorological data are measured continuously and reported hourly at various levels on 10-m (Eureka) and 20-m (Tiksi) flux towers. Tower-based eddy covariance and solar radiation measurements provide a long-term near continuous temporal record of hourly average mass and energy fluxes respectively. The turbulent data are supported by additional atmospheric and surface/snow/permafrost measurements. The data show that sensible heat flux, water vapor and carbon dioxide fluxes were small and mostly irregular in the cold seasons when the ground is covered with snow. However the turbulent fluxes increase rapidly when air temperatures rise above freezing during spring melt and eventually reach a summer maximum. According to our data, strong upward sensible and latent heat fluxes are observed throughout the summer months indicating unstable (convective) conditions on average. This study also shows that the sensible heat flux, water vapor, and carbon dioxide fluxes exhibit clear diurnal cycles during the Arctic summer. This behavior of the sensible heat flux is similar to the diurnal variations in mid-latitudes in summer. On average the turbulent flux of carbon dioxide was mostly negative (uptake by the surface) in summer indicating that the Eureka and Tiksi Arctic sites are net sinks for atmospheric CO2 during the growing season. This result is not unexpected as both Eureka and Tiksi have a summer surface that is extensively covered with vegetation. It is also found that in a summer period observed temporal variability of the carbon dioxide flux was generally in anti-phase with water vapor flux (downward CO2 flux and upward H2O flux). During late summer and early autumn all turbulent fluxes rapidly decreases in magnitude when the air temperature decreases and falls below freezing. Although the Tiksi and Eureka sites have general similarities in annual surface fluxes, some more detailed differences in net characteristics are investigated resulting from such phenomena as the on-shore flow from the Laptev Sea in Tiksi which is absent at the more land-locked Eureka site.

Grachev, A. A.; Uttal, T.; Persson, P. O. G.; Stone, R. S.; Repina, I. A.; Artamonov, A. Y.; Albee, R.

2012-04-01

210

Comparison of different global information sources used in surface radiative flux calculation: Radiative properties of the surface  

Microsoft Academic Search

Direct estimates of surface radiative fluxes that resolve regional and weather-scale variability over the whole globe with reasonable accuracy have only become possible with the advent of extensive global, mostly satellite, data sets within the past couple of decades. The accuracy of these fluxes, estimated to be about 10–15 W\\/m2, is largely limited by the accuracy of the input data

Yuanchong Zhang; William B. Rossow; Paul W. Stackhouse Jr

2007-01-01

211

Comparison of different global information sources used in surface radiative flux calculation: Radiative properties of the near-surface atmosphere  

Microsoft Academic Search

Direct estimates of surface radiative fluxes that resolve regional and weather-scale variability over the whole globe with reasonable accuracy have only become possible with the advent of extensive global, mostly satellite, data sets within the past couple of decades. The accuracy of these fluxes, estimated to be about 10–15 W\\/m2, is largely limited by the uncertainties of the input data

Yuanchong Zhang; William B. Rossow; Paul W. Stackhouse Jr

2006-01-01

212

Comparison of calculated internal tide energy flux with microstructure measurements  

NASA Astrophysics Data System (ADS)

A comparison of the model-derived vertical energy flux from the internal tide with micro-structure measurements is undertaken. The latter data set originates from two field surveys during the Brazil Basin Tracer Release experiment (BBTRE1, BBTRE2) as well as from a third field cruise of the LArval Dispersal along the Deep East-Pacific Rise project (LADDER3). The model for estimating the time-dependent vertical energy flux is based on linear wave theory, and takes into account the the finite depth of the ocean, the spatial variations of the bathymetry and the spatio-temporal variations of the barotropic tide. The temporal average of the vertical energy flux over a limited period (a few days) immediately before the observational time is compared with the depth-integrated observed energy dissipation rate. A rather good correlation was found between the theoretical predictions and the microstructure data from the BBTRE2 field survey, while the comparison made for the BBTRE1 survey yields a low correlation, The model-based estimates of the vertical energy flux are of the correct order of magnitude, and imply that about one third of the internal wave energy dissipates locally. In the case of LADDER3, the comparison between the observations and the model predictions shows a significant correlation, whereas the modelled energy flux is much higher than the observed dissipation, implying a very low dissipation efficiency. A possible explanation is that the sharp topography at the East-Pacific Rise consists of a few isolated seamounts, which should mean that the general background level of internal wave energy is low. If nonlinear wave interaction is essential for wave dissipation, the wave dissipation should then be less local in this region than in the eastern Brazil Basin, with very extended rough topography.

Falahat, Saeed; Nycander, Jonas

2013-04-01

213

Methodes and apparature for precise measurements of solar UV radiation  

Microsoft Academic Search

The precise measurements of solar UV radiation are based on the use of the national primary standards of the flux, irradiance and spectral radiance. Standard sources and detectors were developed for the establishing of spectral and integral irradiance units for regions UV-A, -A1,-A2, -B, -C, herythemical, dangerous and other effective and UV irradiance. The primary standard detector is based on

S. Anevsky; V. Ivanov; O. Minaeva; O. Morozov; V. Sapritsky

2003-01-01

214

A simple yet more accurate model to calculate solar radiative flux in the inhomogeneous atmosphere  

NASA Astrophysics Data System (ADS)

A simple yet more accurate semiempirical model is developed to calculate solar radiative flux in the optically inhomogeneous atmosphere. In the model a parameterized expression of spherical reflectance and transmitance of the atmosphere is confirmed, and the weighted single scatter albedo and weighted asymmetric factor are introduced to fit four empirical correction factors responsible for radiative fluxes in the inhomogeneous atmosphere. For both clean and turbid models, there are 120060 sets of radiative flux simulations for accuracy checks of the model, which cover 0-50 cloud optical depths, 0-0.8 surface reflectance, Junge and Log-normal aerosol size distributions, and 0-0.05 imaginary parts of aerosol refractive indexes. In case of the homogeneous atmosphere, standard errors of the 120060 upward fluxes from the present model are 1.08% and 1.04% for clean and turbid aerosol models, respectively; and those of the downward fluxes are 4.12% and 3.31%. In case of the inhomogeneous atmosphere, standard errors of the upward fluxes from the present model are 3.01% and 3.48% for clean and turbid aerosol models, respectively; and those of the downward fluxes are 4.54% and 4.89%, showing a much better accuracy than the results calculated by using an assumption of the homogeneous atmosphere.

Jinhuan, Qiu

2002-05-01

215

[Research on reducing mold flux's radiative heat transfer based on FTIR and XRD].  

PubMed

The mold fluxes samples containing transition metal oxides TiO2 were designed based on the composition of commercial mold fluxes in continuous casting of steel, and the relation between radiative heat transfer and the content of TiO2 was obtained through FTIR spectrum analysis and XRD analysis. The result of FTIR analysis indicates that TiO2 has a great negative effect on infrared transmittance of flux samples in the wavelength range of 1-6 microm. The result of XRD analysis indicates that crystallization of cuspidine was restrained with addition of TiO2, and CaTiO3 and other phases were found in the samples. The decrease in cuspidine phase is beneficial to strand lubrication in the mold. Radiation heat flux from the strand to the mold was calculated using a radiative heat transfer model concluded in previous study. Addition of TiO2 was found to result in a remarkable decrease in radiation heat flux for both glassy and crystalline samples, and the heat flux tended to decrease with increasing TiO2, with the maximal decrease reaching 30%. As a result of great refraction and scatter at surface and grain boundaries of samples, the negative effect of crystalline samples was much larger than that of the glassy ones. PMID:19445198

Diao, Jiang; Xie, Bing

2009-02-01

216

Corer-reactors for contaminant flux measurement in sediments.  

PubMed

Design details and operating instructions are provided for a sediment corer that can be converted into a reactor for the measurement of the fluxes of contaminants from sediments to overlying waters. The corer-reactor permits measurements, under controlled laboratory conditions, on intact, largely undisturbed sediment cores, without significantly perturbing the physical and chemical conditions found in the field. The design can be constructed in-house for around US dollar 240 (A dollar 400) (excluding motor and corer lid), making it a relatively inexpensive system. PMID:14535336

Jung, R F; Jones, D R; Batley, G E

217

Ultraviolet actinic flux in the stratosphere: An overview of balloon-borne measurements during EASOE, 1991/92  

SciTech Connect

This article presents results of measurements of UV-A and UV-B fluxes as a function of altitude during the EASOE, from balloon borne radiometers. Such information is a fundamental component in models used to study atmospheric chemical reactions which result in ozone depletion. The instruments were able to sense both direct and diffuse radiation, at different solar zenith angles.

Schiller, C.; Hofzumahaus, A.; Mueller, M.; Klein, E.; Roeth, E.P.; Schmidt, U. (Institut fuer Atmosphaerische Chemie, Juelich (Germany))

1994-06-22

218

A Multidimensional Radiation Magnetohydrodynamics Code Based on Flux-Limited Diffusion and HLLD  

NASA Astrophysics Data System (ADS)

We present a multidimensional radiation magnetohydrodynamics (MHD) code based on the high-resolution shock capturing schemes (HRSC), the flux-limited diffusion (FLD) approximation, and the assumption of local thermodynamic equilibrium (LTE). The HRSC, employing a conservative algorithm that accurately ensures conservation of the total energy of MHD is implemented using a third-order Runge-Kutte scheme and the HLLD Riemann solver. In the FLD approximation, because the evolution equations of the radiation energy flux are neglected, this code is easily implemented, though the FLD approximation is less accurate when dealing with highly anisotropic radiation fields in an optically thin region. We carried out classical tests for the MHD and for the subcritical and supercritical radiating shocks. The results show that this code can achieve the necessary accuracy and efficiency to solve the radiation-dominated astrophysical processes with the FLD approximation.

Yang, Xiaohong; Yuan, Feng

2012-08-01

219

Effects of Magnetic Flux Circulation on Radiation Belt and Ring Current Populations  

NASA Astrophysics Data System (ADS)

The orientation of the interplanetary magnetic field (IMF) determines the location of the dayside merging line and the magnetic flux circulation patterns. Magnetic flux circulation determines the amount of energy which enters the magnetosphere and ionosphere. We use the Lyon-Fedder-Mobarry (LFM) global Magneto-Hydro-Dynamic (MHD) code to simulate both idealized and real solar wind cases. We use several satellites to validate the LFM simulation results for the real solar wind case studies. With these cases, we examine the magnetic flux circulation under differing IMF orientations. We also use the Comprehensive Ring Current Model (CRCM) and Radiation Belt Environment (RBE) model to examine the inner magnetospheric response to the orientation of the IMF. We will present the different magnetic flux circulation patterns and the resulting effects on the radiation belt and ring current population.

Mitchell, E. J.; Fok, M. H.

2011-12-01

220

Additional measurements of the radiation environment at the Los Alamos Spallation Radiation Effects Facility at LAMPF  

Microsoft Academic Search

Foil activation dosimetry experiments were conducted in a ''rabbit'' system at the completed Los Alamos Spallation Radiation Effects Facility (LASREF). The ''raffit'' system contains four tubes spaced radially outward 0.12, 0.18, 0.27, and 0.38 meters off beam centerline. Foils were irradiated for 3 to 62 hours to measure the neutron flux and energy spectrum radially from beam centerline, along the

D. R. Davidson; R. C. Reedy; L. R. Greenwood; W. F. Sommer; M. S. Wechsler

1986-01-01

221

Radiative transfer corrections for precise spectroscopic measurements of volcanic emissions  

NASA Astrophysics Data System (ADS)

Passive remote sensing techniques are increasingly being applied to quantitatively measure volcanic emissions. Well established techniques such as COSPEC, mobile DOAS, scanning DOAS, imaging DOAS, and the SO2-camera all use sunlight scattered in the atmosphere as a light source. Therefore, they measure the integrated column density of plume components along the average optical path from the sun to the instrument. To obtain gas concentrations or emission fluxes, however, the average optical path through the volcanic plume must be known. Radiation scattered towards the instrument without having passed through the plume can cause measurement errors. Also, aerosols in volcanic plumes can cause an extension of the optical path, thereby causing an overestimation of emissions. Recent model studies have shown that radiative transfer in and around volcanic plumes can be highly variable and that optical paths depend strongly on distance between plume and instrument, plume SO2 concentration, plume aerosol load, as well as aerosol conditions in the ambient atmosphere. Inaccurate knowledge of radiative transfer can result in significant measurement errors. However, a method for retrieving optical path lengths in volcanic plumes was recently developed and now allows the correction of these errors. The magnitude of radiative transfer induced errors will be demonstrated using exemplary field measurements conducted with both DOAS and SO2-camera techniques. By combining different measurement techniques and applying the novel radiative transfer retrievals, volcanic emissions of SO2 (and other trace gases) can be measured in real time, at a high temporal and spatial resolution, and at high precision.

Kern, C.; Deutschmann, T.; Vogel, L.; Wöhrbach, M.; Wagner, T.; Platt, U.

2009-04-01

222

Preliminary investigation of changes in x-ray multilayer optics subjected to high radiation flux  

Microsoft Academic Search

A variety of metal multilayers was exposed to high x-ray flux using Sandia National Laboratories' PROTO II machine in the gas puff mode. Fluxes incident on the multilayers above 700 MW\\/cm² in total radiation, in nominal 20 ns pulses, were realized. The neon hydrogen- and helium-like resonance lines were used to probe the x-ray reflectivity properties of the multilayers as

M. P. Hockaday; R. L. Blake; J. S. Grosso; M. M. Selph; M. M. Klein; W. Jr. Matuska; M. A. Palmer; R. J. Liefeld

1985-01-01

223

First-wall heat-flux measurements during ELMing H-mode plasma  

SciTech Connect

In this report we present measurements of the diverter heat flux in DIII-D for ELMing H-mode and radiative diverter conditions. In previous work we have examined heat flux profiles in lower single-null diverted plasmas and measured the scaling of the peak heat flux with plasma current and beam power. One problem with those results was our lack of good power accounting. This situation has been improved to better than 80--90% accountability with the installation of new bolometer arrays, and the operation of the entire complement of 5 Infrared (IR) TV cameras using the DAPS (Digitizing Automated Processing System) video processing system for rapid inter-shot data analysis. We also have expanded the scope of our measurements to include a wider variety of plasma shapes (e.g., double-null diverters (DND), long and short single-null diverters (SND), and inside-limited plasmas), as well as more diverse discharge conditions. Double-null discharges are of particular interest because that shape has proven to yield the highest confinement (VH-mode) and beta of all DIII-D plasmas, so any future diverter modifications for DIII-D will have to support DND operation. In addition, the proposed TPX tokamak is being designed for double-null operation, and information on the magnitude and distribution of diverter heat flux is needed to support the engineering effort on that project. So far, we have measured the DND power sharing at the target plates and made preliminary tests of heat flux reduction by gas injection.

Lasnier, C.J.; Allen, S.L.; Hill, D.N. [Lawrence Livermore National Lab., CA (United States); Leonard, A.W.; Petrie, T.W. [General Atomics, San Diego, CA (United States)

1994-01-28

224

The AmeriFlux Network of Long-Term CO{sub 2} Flux Measurement Stations: Methodology and Intercomparability  

SciTech Connect

A portable flux measurement system has been used within the AmeriFlux network of CO{sub 2} flux measurement stations to enhance the comparability of data collected across the network. No systematic biases were observed in a comparison between portable system and site H, LE, or CO{sub 2} flux values although there were biases observed between the portable system and site measurement of air temperature and PPFD. Analysis suggests that if values from two stations differ by greater than 26% for H, 35% for LE, and 32% for CO{sub 2} flux they are likely to be significant. Methods for improving the intercomparability of the network are also discussed.

Hollinger, D. Y.; Evans, R. S.

2003-05-20

225

Effects of horizontal site heterogeneity on turbulent CO2 flux measurements assessed with two independent empirical approaches  

NASA Astrophysics Data System (ADS)

Horizontal heterogeneity can be a major problem for turbulent flux measurements above forest that is difficult to quantify in the field. We use directional analyses with two different empirical approaches in order to quantify the systematic effects of source area heterogeneity on CO2 flux measurements above a Danish beech forest. The forest fetch around the tower varies from 400 m to more than 700 m depending on direction. On average 20% of the forest cover are irregularly distributed conifer plantations. Our hypothesis is that if the fetch had a considerable effect on the flux measurement in 43 m, i.e., ca. 21 m above the displacement height, this will be seen as systematic variability across fluxes measured from different forest sectors. A complication when testing this hypothesis is that the wind direction is correlated with the weather type and that the frequency distribution of the wind direction has two strong maxima, i.e. from SW and E. To consider this, we normalised the flux with its average value within comparable weather conditions. For this we build appropriate air temperature (Tair) x solar radiation (Rg) classes and calculated the flux averages for the elements of this 2 D matrix. The flux values from 8 different forest sectors were then normalised with the flux average within similar combinations of Tair and Rg. Weighting with the frequency compensated for the non-uniform distribution of observations within the weather variable space when calculating an average normalised flux value for each of the 8 forest sectors. These values are interpreted as a measure of systematic effects of site heterogeneity. To further test the validity of this approach, we compared CO2 flux measurements in 43m height with CO2 flux measurements at 34 m height. As the footprint is narrower for the 34m height measurement, effects of horizontal fetch limitation and stand inhomogeneity can be expected to cause systematic spatial patterns of the ratios between the flux measurements from the two heights. The horizontal variability of the ratio is an independent measure of the effects of horizontal heterogeneity on the fluxes estimation. The results of both approaches will be presented and compared. Systematic differences due to site heterogeneity were in the order of 4% relative standard variation during daytime but increased to values of 11% when only night time data were considered. Further comparison with the spatial distribution of the forest fetch and the tree species composition will be used to explain the observed effects. The presented simple empirical approach enables estimation of horizontal homogeneity from a single tower measurement.

Ibrom, Andreas; Wu, Jian; Pilegaard, Kim

2013-04-01

226

Measuring Radiation Damage from Heavy Energetic Ions in Aluminum  

SciTech Connect

An intense beam of 122 MeV/u (9.3 GeV) 76Ge ions was stopped in aluminum samples at the Coupled Cyclotron Facility at NSCL, MSU. Attempts were made at ORNL to measure changes in material properties by measuring changes in electrical resistivity and microhardness, and by transmission electron microscopy characterization, for defect density caused by radiation damage, as a function of depth and integrated ion flux. These measurements are relevant for estimating damage to components at a rare isotope beam facility.

Kostin, M., PI-MSU; Ronningen, R., PI-MSU; Ahle, L., PI-LLNL; Gabriel, T., Scientific Investigation and Development; Mansur, L., PI-ORNL; Leonard, K., ORNL; Mokhov, N., FNAL; Niita, K., RIST, Japan

2009-02-21

227

System having unmodulated flux locked loop for measuring magnetic fields  

DOEpatents

A system (10) for measuring magnetic fields, wherein the system (10) comprises an unmodulated or direct-feedback flux locked loop (12) connected by first and second unbalanced RF coaxial transmission lines (16a, 16b) to a superconducting quantum interference device (14). The FLL (12) operates for the most part in a room-temperature or non-cryogenic environment, while the SQUID (14) operates in a cryogenic environment, with the first and second lines (16a, 16b) extending between these two operating environments.

Ganther, Jr., Kenneth R. (Olathe, KS); Snapp, Lowell D. (Blue Springs, MO)

2006-08-15

228

Instantaneous Radiation Energy Flux and Radiation Power Near the Event Horizon of Slowly Changing Vaidya Black Hole  

NASA Astrophysics Data System (ADS)

By the thin film model of the black hole and the assumption of the local thermal equilibrium, the instantaneous radiation energy flux and radiation power of the slowly changing Vaidya black hole have been studied. The result has been obtained that the thermal radiation of the Vaidya black hole satisfies the generalized Stefan-Boltzmann law. When the cut-off distance and the thin film thickness are both fixed, the instantaneous radiation energy flux of the scalar field near the event horizon of the Vaidya black hole is not only related to the black hole mass, but also to the rate of the change of its event horizon and the average effusion velocity of the radiation particles in the thin film. While its instantaneous radiation power is related to the rate of the change of the event horizon and the average radial effusion velocity of the radiation particles in the thin film. These results indicate that the gravitational field around the black hole and the change of its event horizon will both affect the thermal radiation of the black hole.

Jiang, Ji-Jian

2013-01-01

229

Wind tunnel measurements of pollutant turbulent fluxes in urban intersections  

NASA Astrophysics Data System (ADS)

Wind tunnel experiments have been carried out at the EnFlo laboratory to measure mean and turbulent tracer fluxes in geometries of real street canyon intersections. The work was part of the major DAPPLE project, focussing on the area surrounding the intersection between Marylebone Road and Gloucester Place in Central London, UK. Understanding flow and dispersion in urban streets is a very important issue for air quality management and planning, and turbulent mass exchange processes are important phenomena that are very often neglected in urban modelling studies. The adopted methodology involved the combined use of laser Doppler anemometry and tracer concentration measurements. This methodology was applied to quantify the mean and turbulent flow and dispersion fields within several street canyon intersections. Vertical profiles of turbulent tracer flux were also measured. The technique, despite a number of limitations, proved reliable and allowed tracer balance calculations to be undertaken in the selected street canyon intersections. The experience gained in this work will enable much more precise studies in the future as issues affecting the accuracy of the experimental technique have been identified and resolved.

Carpentieri, Matteo; Hayden, Paul; Robins, Alan G.

2012-01-01

230

Atmospheric VOC Flux Measurements using PTR-MS  

NASA Astrophysics Data System (ADS)

The largest fraction of organic carbon in the atmosphere exists in form of volatile organic compounds (VOC). Highly time-resolved, quantitative measurements of VOC using Proton-transfer-reaction mass spectrometry (PTR-MS) have significantly helped to improve our understanding of the surface atmosphere exchange of VOC over the past decade. This presentation will focus on recent progress in constraining the exchange of VOC on the ecosystem and regional scale. The life cycle of organic carbon is ultimately controlled by emission and deposition processes at the surface. Uncertainties in budgets of VOC and potential ramifications for organic aerosol production in the atmosphere will be discussed based on a synthesis of direct VOC flux measurements performed in a range of different ecosystems. These direct flux measurements will be used to address some outstanding questions concerning (1) the amount of reactive biogenic organic aerosol precursors, (2) the magnitude of deposition processes and (3) the lifetime of reactive biogenic organic aerosol precursors in the atmosphere.

Karl, T.

2011-12-01

231

Vegetation radiative transfer modeling based on virtual flux decomposition  

Microsoft Academic Search

Many physically based approaches for modeling the scattering properties of vegetation (i.e. methods based on radiative transfer models, RTM) suffer from significant shortcomings. In particular, the energy conservation problem has remained unsolved for a long time. This is particularly evident when introducing finite size scattering elements (leaves or shoots) into equations originally describing a turbid medium. This phenomenon, called the

Abdelaziz Kallel

2010-01-01

232

An analysis of the random error affecting CO2 fluxes measured by eddy covariance  

Microsoft Academic Search

This study focuses on random errors associated with eddy covariance flux measurements. This error is heteroscedastic, increases linearly with the flux magnitude and the error on CO2 flux decreases with increasing wind speed. As random errors accumulate in quadrature, they are less critical than systematic errors as far as flux sums are concerned. On the other hand it may affect

Q. Laffineur; B. Heinesch; M. Aubinet

2009-01-01

233

Performance measurements at the fast flux test facility  

SciTech Connect

In 1984, Fast Flux Test Facility (FFTF) management recognized the need to develop a measurement system that would quantify the operational performance of the FFTF and the human resources needed to operate it. Driven by declining budgets and the need to safely manage a manpower rampdown at FFTF, an early warning system was developed. Although the initiating event for the early warning system was the need to safely manage a manpower rampdown, many related uses have evolved. The initial desired objective for the FFTF performance measurements was to ensure safety and control of key performance trends. However, the early warning system has provided a more quantitative, supportable basis upon which to make decisions. From this initial narrow focus, efforts in the FFTF plant and supporting organizations are leading to measurement of and, subsequently, improvements in productivity. Pilot projects utilizing statistical process control have started with longer range productivity improvement.

Baumhardt, R.J.; Newland, D.J.; Praetorius, P.R.

1987-01-01

234

Estimation of surface heat and moisture fluxes over a prairie grassland. I. In situ energy budget measurements incorporating a cooled mirror dew point hygrometer  

SciTech Connect

Attention is focused on in situ measurements taken during FIFE required to support the development and validation of a biosphere model. Seasonal time series of surface flux measurements obtained from two surface radiation and energy budget stations utilized to support the FIFE surface flux measurement subprogram are examined. Data collection and processing procedures are discussed along with the measurement analysis for the complete 1987 test period. 44 refs.

Smith, E.A.; Crosson, W.L.; Tanner, B.D. (Florida State Univ., Tallahassee (United States) Campbell Scientific, Inc., Logan, UT (United States))

1992-11-01

235

Grasland Stable Isotope Flux Measurements: Three Isotopomers of Carbon Dioxide Measured by QCL Spectroscopy  

NASA Astrophysics Data System (ADS)

To improve our understanding of greenhouse gas dynamics of managed ecosystems such as grasslands, we not only need to investigate the effects of management (e.g., grass cuts) and weather events (e.g., rainy days) on carbon dioxide fluxes, but also need to increase the time resolution of our measurements. Thus, for the first time, we assessed respiration and assimilation fluxes with high time resolution (5Hz) stable isotope measurements at an intensively managed farmland in Switzerland (Chamau, 400m ASL). Two different methods were used to quantify fluxes of carbon dioxide and associated fluxes of stable carbon isotopes: (1) the flux gradient method, and (2) the eddy covariance method. During a week long intensive measurement campaign, we (1) measured mixing ratios of carbon dioxide isotopomers (12C16O2, 12C16O18O, 13C16O2) with a Quantum Cascade Laser (QCL, Aerodyne Inc.) spectroscope and (2) collected air samples for isotope analyses (13C/12C) and (18O/16O) of carbon dioxide by Isotope Ratio Mass Spectrometry (IRMS, Finnigan) every two hours, concurrently along a height profile (z = 0.05; 0.10; 0.31; 2.15m). In the following week, the QCL setup was used for closed-path eddy covariance flux measurement of the carbon dioxide isotopomers, with the air inlet located next to an open-path Infra Red Gas Analyzers (IRGA, LiCor 7500) used simultaneously for carbon dioxide measurements. During this second week, an area of grass inside the footprint was cut and harvested after several days. The first results of in-field continuous QCL measurements of carbon dioxide mixing ratios and their stable isotopic ratios show good agreement with IRGA measurements and isotope analysis of flask samples by IRMS. Thus, QCL spectroscopy is a very promising tool for stable isotope flux investigations.

Zeeman, M. J.; Tuzson, B.; Eugster, W.; Werner, R. A.; Buchmann, N.; Emmenegger, L.

2007-12-01

236

Atmospheric Radiation Measurement Climate Research Facility (ACRF) Annual Report 2008  

SciTech Connect

The Importance of Clouds and Radiation for Climate Change: The Earth’s surface temperature is determined by the balance between incoming solar radiation and thermal (or infrared) radiation emitted by the Earth back to space. Changes in atmospheric composition, including greenhouse gases, clouds, and aerosols, can alter this balance and produce significant climate change. Global climate models (GCMs) are the primary tool for quantifying future climate change; however, there remain significant uncertainties in the GCM treatment of clouds, aerosol, and their effects on the Earth’s energy balance. In 1989, the U.S. Department of Energy (DOE) Office of Science created the Atmospheric Radiation Measurement (ARM) Program to address scientific uncertainties related to global climate change, with a specific focus on the crucial role of clouds and their influence on the transfer of radiation in the atmosphere. To reduce these scientific uncertainties, the ARM Program uses a unique twopronged approach: • The ARM Climate Research Facility, a scientific user facility for obtaining long-term measurements of radiative fluxes, cloud and aerosol properties, and related atmospheric characteristics in diverse climate regimes; and • The ARM Science Program, focused on the analysis of ACRF and other data to address climate science issues associated with clouds, aerosols, and radiation, and to improve GCMs. This report provides an overview of each of these components and a sample of achievements for each in fiscal year (FY) 2008.

LR Roeder

2008-12-01

237

Solar, interplanetary, and magnetospheric parameters for the radiation belt energetic electron flux  

NASA Astrophysics Data System (ADS)

In developing models of the radiation belt energetic electron flux, it is important to include the states of the interplanetary medium and the magnetosphere, as well as the solar activity. In this study we choose the log flux je(t;L;E) at 2-6 MeV, as measured by the Proton-Electron Telescope (PET) on SAMPEX in the period 1993-2002, as a representative flux variable and evaluate the usefulness of 17 interplanetary and magnetospheric (IP/MS) parameters in its specification. The reference parameter is the solar wind velocity, chosen because of its known high geoeffectiveness. We use finite impulse response filters to represent the effective coupling of the individual parameters to the log flux. We measure the temporal and spatial scales of the coupling using the impulse response function and the input's geoeffectiveness using the data-model correlation. The correlation profile as a function of L is complex, and we identify its peaks in reference to the radial regions P0 (L = 3.1-4.0, inner edge of the outer belt), P1 (4.1-7.5, main outer belt), and P2 (>7.5, quasi-trapped population), whose boundaries are determined from a radial correlative analysis (Vassiliadis et al., 2003b). Using the profiles, we classify the IP/MS parameters in four categories: (1) For the solar wind velocity and pressure the correlation is high and largely independent of L across P0 and P1, reaching its maximum in L = 4.8-6.1, or the central part of P1. (2) The IMF BSouth component and related IP/MS parameters have a bimodal correlation function, with peaks in region P0 (L = 3.0-4.1) and the geosynchronous orbit region within P1. (3) The IMF BNorth and four other interplanetary or solar irradiance parameters have a minimum correlation in P1, while the highest correlation is in the slot-outer belt boundary (L = 2.5). (4) Finally, the solar wind density has a unique correlation profile, which is anticorrelated with that of the solar wind velocity for certain L shells. We verify this classification using more complex filtering methods as well as standard correlation analysis. The categories correspond to four types of solar-terrestrial interactions, namely, viscous interaction, magnetic reconnection, effects of ionospheric heating, and effects of high solar wind density. The response to these interactions produces the observed inner magnetospheric coherence. In each category the L dependence of the correlation profile helps explain why geoeffective solar wind structures are followed by electron acceleration in some L ranges but not in others.

Vassiliadis, D.; Fung, S. F.; Klimas, A. J.

2005-04-01

238

Three-dimensional discrete ordinates radiation transport calculations of neutron fluxes for beginning-of-cycle at several pressure vessel surveillance positions in the high flux isotope reactor  

SciTech Connect

The objective of this research was to determine improved thermal, epithermal, and fast fluxes and several responses at mechanical test surveillance location keys 2, 4, 5, and 7 of the pressure vessel of the Oak Ridge National Laboratory High Flux Isotope Reactor (HFIR) for the beginning of the fuel cycle. The purpose of the research was to provide essential flux data in support of radiation embrittlement studies of the pressure vessel shell and beam tubes at some of the important locations.

Pace, J.V. III; Slater, C.O.; Smith, M.S.

1993-11-01

239

``Designing Lagrangian experiments to measure regional-scale trace gas fluxes''  

NASA Astrophysics Data System (ADS)

Knowledge of trace gas fluxes at the land surface is essential for understanding the impact of human activities on the composition and radiative balance of the atmosphere. An ability to derive fluxes at the regional scale (on the order of 102-104 km2), at the scale of ecosystems and political borders, is crucial for policy and management responses. Lagrangian ("air mass-following") aircraft experiments have potential for providing direct estimates of regional-scale fluxes by measuring concentration changes in air parcels as they travel over the landscape. Successful Lagrangian experiments depend critically on forecasts of air parcel locations, rate of dispersion of air parcels, and proper assessment of forecast errors. We describe an operational tool to forecast air parcel locations and dispersion and to guide planning of flights for air mass-following experiments using aircraft. The tool consists of a particle dispersion model driven by mesoscale model forecasts from operational centers. The particle model simulates time-reversed motions of air parcels from specified locations, predicting the source regions which influence these locations. Forecast errors are incorporated into planning of Lagrangian experiments using statistics of wind errors derived by comparison with radiosonde data, as well as the model-to-model spread in forecast results. We illustrate the tool's application in a project designed to infer regional CO2 fluxes—the CO2 Budget and Rectification Airborne study, discuss errors in the forecasts, and outline future steps for further improvement of the tool.

Lin, J. C.; Gerbig, C.; Wofsy, S. C.; Chow, V. Y.; Gottlieb, E.; Daube, B. C.; Matross, D. M.

2007-07-01

240

Heat flux measurements for use in physiological and clothing research  

NASA Astrophysics Data System (ADS)

Scientists use passive heat flow meters to measure body heat exchanges with the environment. In recent years, several such sensors have been developed and concerns about their proper calibration have been addressed. However, calibration methods have differed in the geometry of the heated device as well as in the heat transfer mechanism. Therefore, a comparison of calibration methods is needed in order to understand the obtained differences in calibration lines. We chose three commercially available heat flux sensors and placed them on four different heated devices: a hot plate, double hot plate, nude cylinder and a cylinder covered with a spacer material. We found differences between the calibration line of the manufacturer and our own measurements, especially when forced convection was involved as the main heat transfer mechanism. The results showed clearly that the calibration method should be chosen according to the intended purpose of use. In addition, we recommend use a thin, light heat flux sensor with good thermal conduction in human subject studies.

Niedermann, R.; Psikuta, A.; Rossi, R. M.

2013-07-01

241

Gamma heating measurements in a mixed radiation field  

SciTech Connect

Gamma hearing measurements have been made in a low-Z assembly irradiated with 14-MeV neutrons and (n,n{prime}) gammas produced by a Texas Nuclear Model 9400 neutron generator. The assembly is composed of 144 magnesium sleeves (5cm {times} 5cm {times} 60cm {times} 3 mm thick) filled with graphite to simulate a fusion blanket test module. Heating measurements were made in the mid-line of the assembly using a proportional counter operating in the Continuously-varied Bias-voltage Acquisition (CBA) mode. The neutron induced atomic recoil signal was rejected by observing the signal rise-time differences inherent to radiations of different LET. The experiment was modelled using the one-dimensional radiation transport code ANISN/PC. The operating limits of this technique were identified by comparing measurements made at different positions in the assembly and then comparing these measurements to the calculated flux. 7 refs., 5 figs., 1 tab.

Chiu, H.K. (Illinois Univ., Urbana, IL (USA). Dept. of Nuclear Engineering); Bennett, E.F.; Micklich, B.J. (Argonne National Lab., IL (USA))

1990-09-01

242

Development of the Radiation Stabilized Distributed Flux Burner, Phase II Final Report  

Microsoft Academic Search

This report covers progress made during Phase 2 of a three-phase DOE-sponsored project to develop and demonstrate the Radiation Stabilized Distributed Flux burner (also referred to as the Radiation Stabilized Burner, or RSB) for use in industrial watertube boilers and process heaters. The goal of the DOE-sponsored work is to demonstrate an industrial boiler burner with NOx emissions below 9

A. Webb; J. D. Sullivan

1997-01-01

243

A comparison of discrete-ordinates and flux-limited-diffusion methods for modeling radiation transport in radiative shock tubes  

NASA Astrophysics Data System (ADS)

The Center for Radiative Shock Hydrodynamics (CRASH) seeks to improve the predictive capability for models of Omega laser experiments of radiative shock waves. The laser is used to shock, ionize, and accelerate a beryllium plate into a xenon-filled shock tube. These shocks, when driven above a threshold velocity of about 60 km/s, become strongly radiative and convert most of the incoming energy flux into radiation. Radiative shocks have properties that are significantly different from purely hydrodynamic shocks and, in modeling this phenomenon numerically, it is important to compute radiative effects accurately. In this presentation, we examine approaches to modeling radiation transport by comparing two methods: (i) a computationally efficient approximation (multigroup flux-limited diffusion), currently in use in the CRASH code, with (ii) a more accurate discrete-ordinates treatment that is offered by the code PDT. We present a selection of results from a suite of comparison tests, showing both idealized problems and those that are representative of conditions found in the CRASH experiment.

Myra, Eric S.; Hawkins, Wm. Daryl

2011-11-01

244

A Novel Approach for Direct Measurement of Cumulative Water and Solute Mass Fluxes using a Passive Surface Water Flux Meter  

NASA Astrophysics Data System (ADS)

This work describes the development of a novel technique for passive measurement of pollutant loads in flowing surface water systems. Recent changes to the Clean Water Act have prompted a major initiative for the development of a national list of impaired surface waters. According to the law, every state is now responsible for defining the use of each water body and creating a Total Maximum Daily Load (TMDL) to regulate all pollutant loads entering these systems. Current methods for determining pollutant loads typically involve collecting separate instantaneous measurements of water velocities and solute concentrations at discrete points in space and time. The data must be combined, interpolated and integrated after collection to arrive at estimates of local cumulative solute flux and discharge. The frequency with which these parameters are measured typically rely upon the availability of resources (time, money, manpower, etc.) and are often undersampled. A method is presented here for direct measurement of cumulative surface water flux (discharge) and solute flux using a Passive Surface Water Flux Meter (PSFM). The PSFM is designed to directly measure local cumulative water and solute mass fluxes in surface water flow without any active components transmitting or logging data over time. This passive integration of water and solute mass fluxes eliminates the need for independent water flux and concentration measurements and any additional computations. Laboratory trials under steady state and transient conditions were used to test the appropriateness of the PSFM as a device for collecting water quality data. Results from steady state experiments verified the ability of PSFM to accurately measure cumulative water and solute mass flux. Preliminary results from investigations under transient flow conditions also showed promise for measuring pollutant loads in natural systems with this device.

Padowski, J. C.; Jawitz, J. W.; Hatfield, K.; Annable, M. D.; Cho, J.; Klammler, H.

2005-12-01

245

Measurements of ozone vertical flux to ocean and forest  

NASA Astrophysics Data System (ADS)

Ozone flux has been measured from aircraft by the eddy correlation technique over the Gulf of Mexico, the north Pacific Ocean, and a Gulf Coast pine forest. Measurements over the Gulf were obtained in polluted air over relatively warm water, while the north Pacific observations were obtained in pristine air over relatively cold water with nearly neutral stratification. Values of the surface resistance to ozone were about 1800 s/m over both ocean surfaces and 50 s/m over the forest, with an accuracy within 15%. Photochemical production of ozone during midmorning with clear skies over the Gulf of Mexico was 0.2-0.3 ng/cu m per sec, which is an order of magnitude less than that observed over northeastern Colorado.

Lenschow, D. H.; Stankov, B. B.; Pearson, R., Jr.

1982-10-01

246

Measurement of Radiation Symmetry in Z-Pinch Driven Hohlraums  

NASA Astrophysics Data System (ADS)

The z-pinch driven hohlraum (ZPDH) is a promising approach to high yield inertial confinement fusion currently being characterized in experiments on the Sandia Z accelerator [1]. In this concept [2], x rays are produced by an axial z-pinch in a primary hohlraum at each end of a secondary hohlraum. A fusion capsule in the secondary is imploded by a symmetric x-ray flux distribution, effectively smoothed by wall reemission during transport to the capsule position. Capsule radiation symmetry, a critical issue in the design of such a system, is influenced by hohlraum geometry, wall motion and time-dependent albedo, as well as power balance and pinch timing between the two z-pinch x-ray sources. In initial symmetry studies on Z, we used solid low density burnthrough spheres to diagnose highly asymmetric, single-sided-drive hohlraum geometries. We then applied this technique to the more symmetric double z-pinch geometry [3]. As a result of design improvements, radiation flux symmetry in Z double-pinch wire array experiments now exceeds the measurement sensitivity of this self-backlit foam ball symmetry diagnostic (15% max-min flux asymmetry). To diagnose radiation symmetry at the 2 - 5% level attainable with our present ZPDH designs, we are using high-energy x rays produced by the recently-completed Z-Beamlet laser backlighter for point-projection imaging of thin-wall implosion and symmetry capsules. We will present the results of polar flux symmetry measuremets on Z for several ZPDH capsule geometries together with radiosity and radiation-hydrodynamics simulations for comparison. [1] M. E. Cuneo et al., Phys. Plasmas 8,2257(2001); [2] J. H. Hammer et al., Phys. Plasmas 6,2129(1999); [3] D. L. Hanson et al., Bull. Am. Phys. Soc. 45,360(2000).

Hanson, David L.

2001-10-01

247

Radiative flux emitted by a burning PMMA slab  

NASA Astrophysics Data System (ADS)

The degradation of a PMMA sample has been studied based on experimental results obtained for the radiation emission by a burning slab. Observations of the infrared emission perpendicular to the plate, in the range where the optically thin flame is weakly emitting, indicate a plate temperature close to 680 K which is an indication on the surface temperature during the degradation process. Observations from the side allow a flame characterization without the plate emission superimposition. This is a promising way for evaluating data regarding the flame characteristics: temperature, gaz concentration and soot volumetric fraction.

Parent, G.; Acem, Z.; Collin, A.; Berfroi, R.; Boulet, P.; Pizzo, Y.; Mindykowski, P.; Kaiss, A.; Porterie, B.

2012-11-01

248

Spectral line radiation from solar small-scale flux tubes. II  

Microsoft Academic Search

We examine spectral line radiation from small-scale magnetic flux tubes in the solar atmosphere. This is a continuation of work by Kneer et al. (1996). The main difference with the previous investigation is in the choice of the external atmosphere. Earlier we adopted an atmosphere resembling the empirical quiet Sun model for the ambient medium. In the present study, we

S. S. Hasan; F. Kneer; W. Kalkofen

1998-01-01

249

On climate response to changes in the cosmic ray flux and radiative budget  

Microsoft Academic Search

We examine the results linking cosmic ray flux (CRF) variations to global climate change. We then proceed to study various periods over which there are estimates for the radiative forcing, temperature change and CRF variations relative to today. These include the Phanerozoic as a whole, the Cretaceous, the Eocene, the Last Glacial Maximum, the 20th century, as well as the

Nir J. Shaviv

2005-01-01

250

Relations between the ionization or recombination flux and the emission radiation for hydrogen and helium in plasma  

Microsoft Academic Search

On the basis of the collisional-radiative models for neutral hydrogen, and neutral and ionized helium, the relationship between the ionization flux or the recombination flux and the photon emission rate of a representative visible line of each species is investigated. It is found that both fluxes are proportional to the photon emission rate and that the proportionality factor depends rather

Motoshi Goto; Keiji Sawada; Takashi Fujimoto

2002-01-01

251

Seasonal Characteristics of Surface Meteorological and Radiative Fluxes on the East Rongbuk Glacier in Mt. Qomolangma (the Mt. Everest) Region  

NASA Astrophysics Data System (ADS)

Ground-based measurements are essential for understanding alpine glacier dynamics, especially in remote regions where in-situ measurements are extremely limited. The meteorological and radiative fluxes were measured over the accumulation area on the East Rongbuk Glacier, Mt. Qomolangma (the Mt. Everest) at elevation of 6,560 m a.s.l. Measurements were conducted using an automatic weather station (AWS) from May 1 through July 22, 2005 (spring-summer period) and from October 2 of 2007 through January 20 of 2008 (autumn-winter period). Surface meteorological and radiative characteristics were strongly controlled by two major synoptic circulation regimes: the southwesterly Indian monsoon regime in summer and the westerlies in winter. At the AWS site on the East Rongbuk Glacier, north or northwest winds prevail with higher wind speed (up to 35 ms-1 in January) in winter and south or southeast winds predominate after the onset of the southwesterly Indian monsoon with relatively low wind speed in summer. Intensity of incoming shortwave radiation is extremely high due to its high elevation and high reflective surrounding surface. The striking feature is that the observed 10-minute mean incoming shortwave radiative fluxes around local noon were frequently higher than the solar constant at the top of the atmosphere from May through July, 2005. The observed higher-than-solar-constant values are mainly due to the impact of local convective broken clouds and high surface reflectivity over the surrounding terrains. We estimated that horizontal component of received diffusive solar radiation from surrounding terrains ranged from 140 to 310 Wm-2, accounting for about 10 to 25% of the observed incoming shortwave radiation under clear sky conditions. This value could be even higher under overcast cloudy days. The mean surface albedo ranged from 0.72 during summer- spring period and 0.69 during the autumn-winter period. The atmospheric incoming longwave radiation was strongly controlled by cloud conditions and atmospheric moisture content. Overall impact of clouds on net radiation balance is negative in Mt. Qomolangma region. The daily mean net all-wave radiation was positive during the entire spring-summer period and mostly positive during the autumn-winter period except a few overcast cloudy days. On monthly basis, net all-wave radiation was always positive.

Yang, X.; Zhang, T.; Qin, D.; Kang, S.; Qin, X.; Liu, H.

2008-12-01

252

Measurement of the Atmospheric ?e Flux in IceCube  

NASA Astrophysics Data System (ADS)

We report the first measurement of the atmospheric electron neutrino flux in the energy range between approximately 80 GeV and 6 TeV, using data recorded during the first year of operation of IceCube’s DeepCore low-energy extension. Techniques to identify neutrinos interacting within the DeepCore volume and veto muons originating outside the detector are demonstrated. A sample of 1029 events is observed in 281 days of data, of which 496±66(stat)±88(syst) are estimated to be cascade events, including both electron neutrino and neutral current events. The rest of the sample includes residual backgrounds due to atmospheric muons and charged current interactions of atmospheric muon neutrinos. The flux of the atmospheric electron neutrinos is consistent with models of atmospheric neutrinos in this energy range. This constitutes the first observation of electron neutrinos and neutral current interactions in a very large volume neutrino telescope optimized for the TeV energy range.

Aartsen, M. G.; Abbasi, R.; Abdou, Y.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Altmann, D.; Auffenberg, J.; Bai, X.; Baker, M.; Barwick, S. W.; Baum, V.; Bay, R.; Beattie, K.; Beatty, J. J.; Bechet, S.; Becker Tjus, J.; Becker, K.-H.; Bell, M.; Benabderrahmane, M. L.; BenZvi, S.; Berdermann, J.; Berghaus, P.; Berley, D.; Bernardini, E.; Bernhard, A.; Bertrand, D.; Besson, D. Z.; Bindig, D.; Bissok, M.; Blaufuss, E.; Blumenthal, J.; Boersma, D. J.; Bohaichuk, S.; Bohm, C.; Bose, D.; Böser, S.; Botner, O.; Brayeur, L.; Brown, A. M.; Bruijn, R.; Brunner, J.; Buitink, S.; Carson, M.; Casey, J.; Casier, M.; Chirkin, D.; Christy, B.; Clark, K.; Clevermann, F.; Cohen, S.; Cowen, D. F.; Cruz Silva, A. H.; Danninger, M.; Daughhetee, J.; Davis, J. C.; De Clercq, C.; De Ridder, S.; Desiati, P.; de Vries-Uiterweerd, G.; de With, M.; DeYoung, T.; Díaz-Vélez, J. C.; Dreyer, J.; Dunkman, M.; Eagan, R.; Eberhardt, B.; Eisch, J.; Ellsworth, R. W.; Engdegård, O.; Euler, S.; Evenson, P. A.; Fadiran, O.; Fazely, A. R.; Fedynitch, A.; Feintzeig, J.; Feusels, T.; Filimonov, K.; Finley, C.; Fischer-Wasels, T.; Flis, S.; Franckowiak, A.; Franke, R.; Frantzen, K.; Fuchs, T.; Gaisser, T. K.; Gallagher, J.; Gerhardt, L.; Gladstone, L.; Glüsenkamp, T.; Goldschmidt, A.; Golup, G.; Goodman, J. A.; Góra, D.; Grant, D.; Groß, A.; Gurtner, M.; Ha, C.; Haj Ismail, A.; Hallgren, A.; Halzen, F.; Hanson, K.; Heereman, D.; Heimann, P.; Heinen, D.; Helbing, K.; Hellauer, R.; Hickford, S.; Hill, G. C.; Hoffman, K. D.; Hoffmann, R.; Homeier, A.; Hoshina, K.; Huelsnitz, W.; Hulth, P. O.; Hultqvist, K.; Hussain, S.; Ishihara, A.; Jacobi, E.; Jacobsen, J.; Japaridze, G. S.; Jero, K.; Jlelati, O.; Kaminsky, B.; Kappes, A.; Karg, T.; Karle, A.; Kelley, J. L.; Kiryluk, J.; Kislat, F.; Kläs, J.; Klein, S. R.; Köhne, J.-H.; Kohnen, G.; Kolanoski, H.; Köpke, L.; Kopper, C.; Kopper, S.; Koskinen, D. J.; Kowalski, M.; Krasberg, M.; Kroll, G.; Kunnen, J.; Kurahashi, N.; Kuwabara, T.; Labare, M.; Landsman, H.; Larson, M. J.; Lesiak-Bzdak, M.; Leute, J.; Lünemann, J.; Madsen, J.; Maruyama, R.; Mase, K.; Matis, H. S.; McNally, F.; Meagher, K.; Merck, M.; Mészáros, P.; Meures, T.; Miarecki, S.; Middell, E.; Milke, N.; Miller, J.; Mohrmann, L.; Montaruli, T.; Morse, R.; Nahnhauer, R.; Naumann, U.; Niederhausen, H.; Nowicki, S. C.; Nygren, D. R.; Obertacke, A.; Odrowski, S.; Olivas, A.; Olivo, M.; O'Murchadha, A.; Panknin, S.; Paul, L.; Pepper, J. A.; Pérez de los Heros, C.; Pfendner, C.; Pieloth, D.; Pirk, N.; Posselt, J.; Price, P. B.; Przybylski, G. T.; Rädel, L.; Rawlins, K.; Redl, P.; Resconi, E.; Rhode, W.; Ribordy, M.; Richman, M.; Riedel, B.; Rodrigues, J. P.; Rott, C.; Ruhe, T.; Ruzybayev, B.; Ryckbosch, D.; Saba, S. M.; Salameh, T.; Sander, H.-G.; Santander, M.; Sarkar, S.; Schatto, K.; Scheel, M.; Scheriau, F.; Schmidt, T.; Schmitz, M.; Schoenen, S.; Schöneberg, S.; Schönherr, L.; Schönwald, A.; Schukraft, A.; Schulte, L.; Schulz, O.; Seckel, D.; Seo, S. H.; Sestayo, Y.; Seunarine, S.; Sheremata, C.; Smith, M. W. E.; Soiron, M.; Soldin, D.; Spiczak, G. M.; Spiering, C.; Stamatikos, M.; Stanev, T.; Stasik, A.; Stezelberger, T.; Stokstad, R. G.; Stößl, A.; Strahler, E. A.; Ström, R.; Sullivan, G. W.; Taavola, H.; Taboada, I.; Tamburro, A.; Ter-Antonyan, S.; Tilav, S.; Toale, P. A.; Toscano, S.; Usner, M.; van der Drift, D.; van Eijndhoven, N.; Van Overloop, A.; van Santen, J.; Vehring, M.; Voge, M.; Vraeghe, M.; Walck, C.; Waldenmaier, T.; Wallraff, M.; Wasserman, R.; Weaver, Ch.; Wellons, M.; Wendt, C.; Westerhoff, S.; Whitehorn, N.; Wiebe, K.; Wiebusch, C. H.; Williams, D. R.; Wissing, H.; Wolf, M.; Wood, T. R.; Woschnagg, K.; Xu, C.; Xu, D. L.; Xu, X. W.; Yanez, J. P.; Yodh, G.; Yoshida, S.; Zarzhitsky, P.; Ziemann, J.; Zierke, S.; Zilles, A.; Zoll, M.

2013-04-01

253

Improvements to measuring water flux in the vadose zone.  

PubMed

Evaluating the impact of land use practices on ground water quality has been difficult because few techniques are capable of monitoring the quality and quantity of soil water flow below the root zone without disturbing the soil profile and affecting natural flow processes. A recently introduced method, known as equilibrium tension lysimetry, was a major improvement but it was not a true equilibrium since it still required manual intervention to maintain proper lysimeter suction. We addressed this issue by developing an automated equilibrium tension lysimeter (AETL) system that continuously matches lysimeter tension to soil-water matric potential of the surrounding soil. The soil-water matric potential of the bulk soil is measured with a heat-dissipation sensor, and a small DC pump is used to apply suction to a lysimeter. The improved automated approach reported here was tested in the field for a 12-mo period. Powered by a small 12-V rechargeable battery, the AETLs were able to continuously match lysimeter suction to soil-water matric potential for 2-wk periods with minimal human attention, along with the added benefit of collecting continuous soil-water matric potential data. We also demonstrated, in the laboratory, methods for continuous measurement of water depth in the AETL, a capability that quantifies drainage on a 10-min interval, making it a true water-flux meter. Equilibrium tension lysimeters have already been demonstrated to be a reliable method of measuring drainage flux, and the further improvements have created a more effective device for studying water drainage and chemical leaching through the soil matrix. PMID:15224955

Masarik, Kevin C; Norman, John M; Brye, Kristofor R; Baker, John M

254

Radiation Effects on Oscillating Vertical Plate with Uniform Heat and Mass Flux  

NASA Astrophysics Data System (ADS)

Thermal radiation effects on flow past an impulsively started infinite vertical oscillating plate with uniform heat and mass flux is studied. The fluid considered here is a gray, absorbing-emitting radiation but a nonscattering medium. The dimensionless governing equations are solved using the Laplace-transform technique. The velocity, temperature and concentration are studied for different physical parameters such as the radiation parameter, phase angle, Schmidt number and time. The variation of the skin-friction for different values of the parameters is also shown in a table

Chandrakala, P.; Bhaskar, P. Narayana

2013-08-01

255

Measurement of particulate matter emission fluxes from a beef cattle feedlot using Flux-gradient technique  

Technology Transfer Automated Retrieval System (TEKTRAN)

Data on air emissions from open-lot beef cattle feedlots are limited. This research was conducted to determine PM10 emission fluxes from a commercial beef cattle feedlot in Kansas using the flux-gradient technique, a widely-used micrometeorological method for gaseous emissions from open sources. V...

256

Simulation of the eddy accumulation method for measuring pollutant fluxes  

SciTech Connect

A numerical simulation of the eddy accumulation technique for measuring pollutant fluxes has been used to test the sensitivity of the method to errors from various sources including sensor orientation, sampling limitations and chemical resolution. The tests were conducted using artificial pollutant concentration signals derived from actual meteorological data, in order to avoid the possibility of including unwanted errors by employing a poor quality pollutant signal. It is found that to detect a pollutant deposition velocity of 0.1 cm/sec it is necessary to maintain the linear sampling characteristics over a dynamic range corresponding to two orders of magnitude of vertical wind speed to maintain sampling zero offsets to less than 0.02 sigma of equivalent standard vertical velocity and to resolve chemical concentration differences amounting to about 0.4 percent in typical conditions. 5 references.

Hicks, B.B.; Mcmillen, R.T.

1984-04-01

257

Recommended Procedures for Measuring Radon Fluxes from Disposal Sites of Residual Radioactive Materials.  

National Technical Information Service (NTIS)

This report recommends instrumentation and methods suitable for measuring radon fluxes emanating from covered disposal sites of residual radioactive materials such as uranium mill tailings. Problems of spatial and temporal variations in radon flux are dis...

J. A. Young V. W. Thomas P. O. Jackson

1983-01-01

258

Water flux measurement and prediction in young cashew trees using sap flow data  

NASA Astrophysics Data System (ADS)

Measurements of sap flow, meteorological parameters, soil water content and tension were made for 4 months in a young cashew (Anacardium occidentale L.) plantation during the 2002 rainy season in Ejura, Ghana. This experiment was part of a sustainable water management project in West Africa. The Granier system was used to measure half-hourly whole-tree sap flow. Weather variables were observed with an automatic weather station, whereas soil moisture and tension were measured with a Delta-T profile probe and tensiometers respectively. Clearness index (CI), a measure of the sky condition, was significantly correlated with tree transpiration (r2 = 0.73) and potential evaporation (r2 = 0.86). Both diurnal and daily stomata conductance were poorly correlated with the climatic variables. Estimated daily canopy conductance gc ranged from 4.0 to 21.2 mm s-1, with a mean value of 8.0 +/- 3.3 mm s-1. Water flux variation was related to a range of environmental variables: soil water content, air temperature, solar radiation, relative humidity and vapour pressure deficit. Linear and non-linear regression models, as well as a modified Priestley-Taylor formula, were fitted with transpiration, and the well-correlated variables, using half-hourly measurements. Measured and predicted transpiration using these regression models were in good agreement, with r2 ranging from 0.71 to 0.84. The computed measure of accuracy indicated that a non-linear model is better than its corresponding linear one. Furthermore, solar radiation, CI, clouds and rain were found to influence tree water flux.

Oguntunde, Philip G.; van de Giesen, Nick

2005-10-01

259

Measurements of Smith--Purcell radiation  

SciTech Connect

We present experimental results on Smith--Purcell radiation. Our primary interest was in the measurement of radiation angular distribution, output power, and spectral content. The variations of the angular distribution and the output power were shown for different electron-beam voltages and currents. The output power measured with a 3-mA and 120-kV electron beam was {similar to}30 {mu}W/cm{sup 2}-sr. The spectral analysis of the radiation shows excellent agreement between the measurements and the theoretical predictions. Our results were compared with those obtained by Gover et al. (J. Opt. Soc. Am. B 1, 723 (1984)).

Shih, I.; Salisbury, W.; Masters, D.; Chang, D. (Hughes Aircraft Company, Support Systems, P.O. Box 9399, Long Beach, California 90810-0399 (US))

1990-03-01

260

Accelerated detector-quantum field correlations: From vacuum fluctuations to radiation flux  

SciTech Connect

In this paper we analyze the interaction of a uniformly accelerated detector with a quantum field in (3+1)D spacetime, aiming at the issue of how kinematics can render vacuum fluctuations the appearance of thermal radiance in the detector (Unruh effect) and how they engender flux of radiation for observers afar. Two basic questions are addressed in this study: (a) How are vacuum fluctuations related to the emitted radiation? (b) Is there emitted radiation with energy flux in the Unruh effect? We adopt a method which places the detector and the field on an equal footing and derive the two-point correlation functions of the detector and of the field separately with full account of their interplay. From the exact solutions, we are able to study the complete process from the initial transient to the final steady state, keeping track of all activities they engage in and the physical effects manifested. We derive a quantum radiation formula for a Minkowski observer. We find that there does exist a positive radiated power of quantum nature emitted by the detector, with a hint of certain features of the Unruh effect. We further verify that the total energy of the dressed detector and a part of the radiated energy from the detector is conserved. However, this part of the radiation ceases in steady state. So the hint of the Unruh effect in radiated power is actually not directly from the energy flux that the detector experiences in Unruh effect. Since all the relevant quantum and statistical information about the detector (atom) and the field can be obtained from the results presented here, they are expected to be useful, when appropriately generalized, for addressing issues of quantum information processing in atomic and optical systems, such as quantum decoherence, entanglement, and teleportation.

Lin, S.-Y.; Hu, B.L. [Center for Quantum and Gravitational Physics, Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan (China) and Department of Physics, University of Maryland, College Park, Maryland 20742-4111 (United States)

2006-06-15

261

Accelerated detector-quantum field correlations: From vacuum fluctuations to radiation flux  

NASA Astrophysics Data System (ADS)

In this paper we analyze the interaction of a uniformly accelerated detector with a quantum field in (3+1)D spacetime, aiming at the issue of how kinematics can render vacuum fluctuations the appearance of thermal radiance in the detector (Unruh effect) and how they engender flux of radiation for observers afar. Two basic questions are addressed in this study: (a) How are vacuum fluctuations related to the emitted radiation? (b) Is there emitted radiation with energy flux in the Unruh effect? We adopt a method which places the detector and the field on an equal footing and derive the two-point correlation functions of the detector and of the field separately with full account of their interplay. From the exact solutions, we are able to study the complete process from the initial transient to the final steady state, keeping track of all activities they engage in and the physical effects manifested. We derive a quantum radiation formula for a Minkowski observer. We find that there does exist a positive radiated power of quantum nature emitted by the detector, with a hint of certain features of the Unruh effect. We further verify that the total energy of the dressed detector and a part of the radiated energy from the detector is conserved. However, this part of the radiation ceases in steady state. So the hint of the Unruh effect in radiated power is actually not directly from the energy flux that the detector experiences in Unruh effect. Since all the relevant quantum and statistical information about the detector (atom) and the field can be obtained from the results presented here, they are expected to be useful, when appropriately generalized, for addressing issues of quantum information processing in atomic and optical systems, such as quantum decoherence, entanglement, and teleportation.

Lin, Shih-Yuin; Hu, B. L.

2006-06-01

262

Measurements of human body microwave radiation  

Microsoft Academic Search

Major problems of registering microwave radiation of human body have been considered. It is pointed out that they are caused by at least three factors which may considerably influence the experimental results and their interpretation, namely: (1) properties of the radiation (their low intensity primarily); (2) features of measurements that implement waveguide techniques; (3) peculiar features of the emission medium

G. V. Ponezha; S. G. Ponezha; A. I. Nizhelskaya

2003-01-01

263

Role of plant-generated water vapor and VOC fluxes in shoot chamber measurements of O3 and NOx  

NASA Astrophysics Data System (ADS)

One of the processes underlying the atmospheric balance of O3 and NOx is their interaction with vegetation. Both are removed, absorbed, and NOx potentially also emitted by foliage. Uncertainties remain on relevant factors controlling O3 and NOx interactions with foliage as well as on including them in large-scale models. One reason for the uncertainty is that chamber measurements of O3 and NOx fluxes are complicated. These reactive gases are adsorbed and desorbed on the chamber walls, depending on the conditions (i.e. humidity). These artefact gas fluxes (chamber blank) must also be quantified and taken into account in the data analysis. Their importance increases when measuring in clean air, where the fluxes are generally small. At near-zero concentrations, the fluxes may not pass the detection limit of the instrumentation, which usually means it is not possible to separate the plant-related fluxes from the chamber blank. The long-term field measurements at the SMEAR II station in Hyytiälä, Southern Finland, have provided valuable insights into O3 and NOx exchange (i.e. Raivonen & al. 2009, Altimir & al. 2006). This project builds up on the expertise and conclusions from these works. The aim of this study was to improve the reliability of the measuring system by checking the role of potential measuring artefact(s). A live shoot, enclosed in a chamber, creates a water vapor in the chamber flux by transpiring. There are also biogenic VOC emissions from the shoot. In principle, these may affect the reactions of O3 and possibly NOx in the chamber. The potential interference of these fluxes created naturally during chamber closure is a main concern. Their effect on the O3 and NOx flux measurements has been tested with field calibrations in 2010-2011. In these calibrations, a controlled water vapor /VOC flux was fed into an empty shoot measurement chamber, and the H2O, CO2, O3 and NOx fluxes created in the chamber were measured. The created water vapor flux pattern was modified to either simulate shoot transpiration or to break the close connection of natural daily variation in transpiration, radiation and temperature. We will present results of this experiment. The project is funded by the Maj and Tor Nessling Foundation and the Ella and Georg Ehnrooth Foundation.

Joensuu, J.; Altimir, N.; Raivonen, M.; Kolari, P.; Keronen, P.; Vesala, T.; Bäck, J.; Hari, P.; Järvinen, E.; Nikinmaa, E.

2012-04-01

264

Techniques for radiation measurements: microdosimetry and dosimetry.  

PubMed

Experimental microdosimetry is concerned with the determination of radiation quality and how this can be specified in terms of the distribution of energy deposition arising from the interaction of a radiation field with a particular target site. This paper discusses various techniques that have been developed to measure radiation energy deposition over the three orders of magnitude of site-size; nanometer, micrometer and millimetre, which radiation biology suggests is required to fully account for radiation quality. Inevitably, much of the discussion will concern the use of tissue-equivalent proportional counters and variants of this device, but other technologies that have been studied, or are under development, for their potential in experimental microdosimetry are also covered. Through an examination of some of the quantities used in radiation metrology and dosimetry the natural link with microdosimetric techniques will be shown and the particular benefits of using microdosimetric methods for dosimetry illustrated. PMID:17223638

Waker, A J

2007-01-12

265

XUV polarimeter for undulator radiation measurements  

SciTech Connect

A polarimeter for x-ray and vacuum ultraviolet (XUV) radiation was built to measure the spatial spectral dependence of the polarization of the light produced by the new undulator at the U5 beamline at NSLS. The fourth-harmonic radiation was measured, and it does not agree with predictions based on ideal simulation codes in the far-field approximation. 13 ref., 7 figs.

Gluskin, E.; Mattson, J.E.; Bader, S.D.; Viccaro, P.J. (Argonne National Lab., IL (United States)); Barbee, T.W. Jr. (Lawrence Livermore National Lab., CA (United States)); Brookes, N. (Brookhaven National Lab., Upton, NY (United States)); Pitas, A. (Baker Mfg. Co., Evansville, WI (United States)); Watts, R. (National Inst. of Standards and Technology, Gaithersburg, MD (United States))

1991-01-01

266

Trace element measurements using white synchrotron radiation  

SciTech Connect

Synchrotron radiation, when used for x-ray fluorescence (XRF) has several advantages over conventional x-ray sources. Our group at Brookhaven National Laboratory is developing the equipment and expertise to make XRF measurements with synchrotron radiation. The apparatus is briefly described, along with the alignment techniques. Some minimum detectable limits for trace elements in thin biological standards measured with white light irradiations are presented.

Hanson, A.L.; Jones, K.W.; Gordon, B.M.; Pounds, J.G.; Kwiatek, W.M.; Long, G.J.; Rivers, M.L.; Sutton, S.R.

1986-11-10

267

The magnetic, basal, and radiative-equilibrium components in Mount Wilson Ca II H + K fluxes  

SciTech Connect

Mount Wilson Ca II H + K flux measurements of cool dwarf stars are analyzed and compared with stellar Mg II h + k fluxes, variability amplitudes, rotation rates, and solar data. It is concluded that the Mount Wilson Ca II H + K fluxes comprise three principal parts: (1) a photospheric contribution in the line wings, (2) a basal chromospheric component that appears to be unrelated to stellar magnetic activity and is, therefore, possibly nonmagnetic in origin, and (3) a chromospheric component which is associated with magnetically active regions and the (quiet and active) network. The basal chromosphere appears to cover the entire surface of magnetically inactive stars. The basal Ca II H + K flux density for solar-type stars equals the average emission observed in the centers of solar supergranulation cells, where the magnetic flux density is small. 27 refs.

Schrijver, C.J.; Dobson, A.K.; Radick, R.R. (National Solar Observatory, Sunspot, NM (USA); Joint Institute for Laboratory Astrophysics, Boulder, CO (USA))

1989-06-01

268

A highly portable, rapidly deployable system for eddy covariance measurements of CO2 fluxes  

SciTech Connect

To facilitate the study of flux heterogeneity within a region, the authors have designed, built, and field-tested a highly portable, rapidly deployable, eddy covariance CO{sub 2} flux measurement system. The system is built from off-the-shelf parts and was assembled at a minimal cost. The unique combination of features of this system allow for a very rapid deployment with a minimal number of field personnel. The system is capable of making high precision, unattended measurements of turbulent CO{sub 2} fluxes, latent heat (LE) fluxes, sensible heat fluxes (H), and momentum transfer fluxes. In addition, many of the meteorological and ecosystem variables necessary for quality control of the fluxes and for running ecosystem models are measured. A side-by-side field comparison of the system at a pair of established AmeriFlux sites has verified that, for single measurements, the system is capable of CO{sub 2} flux accuracy of about {+-} 1.2 {micro}mole/m{sup 2}/sec, LE flux accuracy of about {+-} 15 Watts/m{sup 2}, H flux accuracy of about {+-} 7 Watts/m{sup 2}, and momentum transfer flux accuracy of about {+-} 11 gm-m/sec/sec. System deployment time is between 2 and 4 hours by a single person. The system was measured to draw between 30 and 35 Watts of power and may be run from available line power, storage batteries, or solar panels.

Billesbach, David P.; Fischer, Marc L.; Torn, Margaret S.; Berry, Joe A.

2001-09-19

269

Estimation of the climate feedback parameter by using radiative fluxes from CERES EBAF  

NASA Astrophysics Data System (ADS)

Top-of-the-Atmosphere (TOA) net radiative flux anomalies from Clouds and Earth's Radiant Energy Systems (CERES) Energy Balanced and Filled (EBAF) and surface air temperature anomalies from HadCRUT3 were compared for the time interval September 2000-May 2011. In a phase plane plot with the radiative flux anomalies lagging the temperature anomalies with 7 months the phase plane curve approached straight lines during about an eight months long period at the beginning and a five year period at the end of the interval. Both of those periods, but more clearly the latter one, could be connected to the occurrence of distinct El Niño Southern Oscillation (ENSO) episodes. This result is explained by using a hypothesis stating that non-radiative forcing connected to the ENSO is dominating the temperature changes during those two periods and that there is a lag between the temperature change and the radiative flux feedback. According to the hypothesis the slopes of the straight lines equal the value of the climate feedback parameter. By linear regression based on the mentioned five year period the value of the climate feedback parameter was estimated to 5.5 ± 0.6 W m-2 K-1 (± two standard errors).

Björnbom, P.

2013-01-01

270

A Summary of Mass Flux Measurements in Solid 4He  

NASA Astrophysics Data System (ADS)

Here we provide a summary and brief review of some of the work done with solid 4He at the University of Massachusetts Amherst below a sample pressure of 28 bar. The motivation for the work has been to attempt to pass 4He atoms through solid 4He without directly applying mechanical pressure to the solid itself. The specific technique chosen is limited to pressures near the melting curve and was initially designed to provide a yes/no answer to the question of whether or not it might be possible to observe such a mass flux. The thermo-mechanical effect and direct mass injection have been separately used to create chemical potential differences between two reservoirs of superfluid 4He connected to each other through superfluid-filled Vycor rods in series with solid 4He, which is in the hcp region of the phase diagram. The thermo-mechanical effect is a more versatile approach. And, in a particular symmetric application it is designed to provide a mass flux with little or no net increase in the density of the solid. Our observations, off but near the melting curve, have included: (1) the presence of an increasing DC flux of atoms through the solid-filled cell with decreasing temperature below ?650 mK and no flux above this temperature; (2) the presence of a flux minimum and flux instability in the vicinity of 75-80 mK, with a flux increase at lower temperatures; (3) the temperature dependence of the flux above 100 mK and the dependence of the flux on the net driving chemical potential difference provide interesting insights on the possible mechanism that leads to the flux above 100 mK. The most recent data suggest that whatever is responsible for the flux in solid 4He, at least for T>100 mK, may be an example of a Bosonic Luttinger liquid.

Hallock, R. B.; Ray, M. W.; Vekhov, Y.

2012-11-01

271

Plasma Lens for High Flux X-Ray Radiation  

SciTech Connect

We have developed the Scaled Thermal Explosion Experiment (STEX) to provide a database of reaction violence from thermal explosion for explosives of interest. Such data are needed to develop, calibrate, and validate predictive capability for thermal explosions using simulation computer codes. A cylinder of explosive 25, 50 or 100 mm in diameter, is confined in a steel cylinder with heavy end caps, and heated under controlled conditions until reaction. Reaction violence is quantified through non-contact micropower impulse radar measurements of the cylinder wall velocity and by strain gauge data at reaction onset. Here we describe the test concept, design and diagnostic recording, and report results with HMX- and RDX-based energetic materials.

Shlyaptsev, V N; Toor, A; Tatchyn, R O

2001-12-17

272

Evaluation of the flux gradient technique for measurement of ozone surface fluxes over snowpack at Summit, Greenland  

NASA Astrophysics Data System (ADS)

A multi-step procedure for investigating ozone surface fluxes over polar snow by the tower gradient method was developed and evaluated. These measurements were then used to obtain five months (April-August 2004) of turbulent ozone flux data at the Summit research camp located in the center of the Greenland ice shield. Turbulent fluxes were determined by the gradient method incorporating tower measurements of (a) ozone gradients measured by commercial ultraviolet absorption analyzers, (b) ambient temperature gradients using aspirated thermocouple sensors, and (c) wind speed gradients determined by cup anemometers. All gradient instruments were regularly inter-compared by bringing sensors or inlets to the same measurement height. The developed protocol resulted in an uncertainty on the order of 0.1 ppbv for 30-min averaged ozone gradients that were used for the ozone flux calculations. This protocol facilitated a lower sensitivity threshold for the ozone flux determination of ∼8 × 10-3?g m-2 s-1, respectively ∼0.01 cm s-1 for the ozone deposition velocity for typical environmental conditions encountered at Summit. Uncertainty in the 30-min ozone exchange measurements (evaluated by the Monte Carlo statistical approach) was on the order of 10-2 cm s-1. This uncertainty typically accounted to ~20-100% of the ozone exchange velocities that were determined. These measurements are among the most sensitive ozone deposition determinations reported to date. This flux experiment allowed for measurements of the relatively low ozone uptake rates encountered for polar snow, and thereby the study of their environmental and spring-versus-summer dependencies.

Bocquet, F.; Helmig, D.; van Dam, B. A.; Fairall, C. W.

2011-10-01

273

Soil air and soil flux measurements of 222Radon and CO2: A soil flux parametrization at Lutjewad (NL)  

NASA Astrophysics Data System (ADS)

Atmospheric 222Radon concentration measurements are used as a valuable transport tracer verifying the transport part of Carbon Cycle and Greenhouse Gas models. The production rate of the radioactive noble gas 222Radon (T1?2 = 3.8 days) by radioactive decay of 226Radium in the soil is constant, the absolute quantity depending on the local soil Radium concentration. The flux of 222Radon to the atmosphere (the soil exhalation, or effective atmospheric production rate), however, is not constant. It strongly depends on soil texture, soil humidity, precipitation and other parameters, but is nearly constant if these parameters stay unchanged. Recently, an effort has been done to predict this flux rate with widely available γ-dosimetry measurements (Szegvary et al., Predicting terrestrial 222Rn-flux using gamma dose rate as a proxy, ACP 7, 2789-2795, 2007), but real 222Radon-flux measurements are sparse. 222Radon undergoes the same transport processes on the way from soil to atmosphere as any other soil-derived (greenhouse) gas. This makes 222Radon an ideal tracer to separate variations in e.g. soil CO2-production from changes in the soil-atmosphere CO2-transport, both being reflected in the total soil-atmosphere CO2-flux. At the atmospheric measurement site Lutjewad in the north of the Netherlands (53N24'18", 6E21'13", www.rug.nl/ees/onderzoek/cio/projecten/atmosphericgases) we started in 2006 with the measurements of the soil 222Radon and CO2 concentration through soil probes as well as the Radon and CO2 soil fluxes by means of an automatic soil chamber. While there are up to eight soil air measurements per day, the soil chamber is automatically closed twice per day. The station is situated directly on the Waddensea dike at an elevation of 1 m a.s.l. on seaclay soil. The groundwater table shows variations between 0.5 m and 2 m below terrain. From our measurements we find that in the dryer summer season, from April to July, the mean 222Radon-flux can be up to 40 % higher than the during the rest of the year, but the variability is generally very high. Short-term flux minima are mainly due to precipitation events. First results will be shown of the parameterization of the 222Radon and CO2 fluxes with the groundwater level, soil temperature and humidity, rain events and atmospheric pressure changes.

Neubert, R. E. M.; Kettner, E.; Palstra, S. W. L.; Hoekman, S.; van der Graaf, E. R.

2009-04-01

274

Solar radiation in the Mackenzie River Basin: Retrieval from satellite measurements and evaluation of atmospheric models  

NASA Astrophysics Data System (ADS)

Accurate determination of solar flux at the top of the atmosphere (TOA), which can only be made from satellite observations, is essential for climate studies. In the present study, we developed a new technique to derive the solar fluxes at the TOA and at the surface from operational meteorological satellites. Two key steps in the technique are the narrowband to broadband (NTB) conversion and deriving the net solar flux at the surface from TOA observations. We developed a new NTB conversion algorithm from ScaRaB observations and radiation transfer model simulations. In deriving the net solar fluxes at the surface from TOA measurements, the effects of absorbing aerosols have been investigated. The technique described above has been applied to AVHRR data to derive a dataset of solar flux in the Mackenzie River Basin (MRB) for the Canadian GEWEX Enhanced Study (CAGES) period from June 1998 to September 1999. The derived net solar fluxes at the surface were evaluated with the surface measurements in the basin and good agreement was achieved. Radiation fields from two atmospheric models used in the Mackenzie GEWEX Study (MAGS) project, the Canadian Regional Climate Model (CRCM) and the Global Environmental Multiscale (GEM) model, were evaluated against satellite retrievals of radiation fluxes in the present study. It was found that the CRCM simulated the TOA reflected flux well in the MRB for the summer of 1994, but large biases were found in the partition of absorbed solar radiation between the atmosphere and the earth's surface. The net surface solar radiation was found to be overestimated by about 15% in the CRCM. Evaluation of the preliminary output from the new version of CRCM shows substantial improvement. Evaluation of radiation fields from the GEM model shows good agreement under clear skies, but under cloudy skies, the TOA albedo simulated by the GEM model in the MRB was about 30% lower than observations for the summer of 1999.

Feng, Jian

275

Lava discharge rates from satellite-measured heat flux  

Microsoft Academic Search

A commonly used method to convert lava flow area to volume flux using low spatial resolution satellite data rests on two primary assumptions, that: (1) volume flux is related to flow area, and (2) lava surfaces cool exponentially with time and distance from the source. Field data show that both assumptions are valid. The ensuing relationship is an empirical one

Andrew J. L. Harris; Stephen M. Baloga

2009-01-01

276

Atmospheric radiation measurement program facilities newsletter, June 2002.  

SciTech Connect

ARM Intensive Operational Period Scheduled to Validate New NASA Satellite--Beginning in July, all three ARM sites (Southern Great Plains [SGP], North Slope of Alaska, and Tropical Western Pacific; Figure 1) will participate in the AIRS Validation IOP. This three-month intensive operational period (IOP) will validate data collected by the satellite-based Atmospheric Infrared Sounder (AIRS) recently launched into space. On May 4, the National Aeronautics and Space Administration (NASA) launched Aqua, the second spacecraft in the Earth Observing System (EOS) series. The EOS satellites monitor Earth systems including land surfaces, oceans, the atmosphere, and ice cover. The first EOS satellite, named Terra, was launched in December 1999. The second EOS satellite is named Aqua because its primary focus is understanding Earth's water cycle through observation of atmospheric moisture, clouds, temperature, ocean surface, precipitation, and soil moisture. One of the instruments aboard Aqua is the AIRS, built by the Jet Propulsion Laboratory, a NASA agency. The AIRS Validation IOP complements the ARM mission to improve understanding of the interactions of clouds and atmospheric moisture with solar radiation and their influence on weather and climate. In support of satellite validation IOP, ARM will launch dedicated radiosondes at all three ARM sites while the Aqua satellite with the AIRS instrument is orbiting overhead. These radiosonde launches will occur 45 minutes and 5 minutes before selected satellite overpasses. In addition, visiting scientists from the Jet Propulsion Laboratory will launch special radiosondes to measure ozone and humidity over the SGP site. All launches will generate ground-truth data to validate satellite data collected simultaneously. Data gathered daily by ARM meteorological and solar radiation instruments will complete the validation data sets. Data from Aqua-based instruments, including AIRS, will aid in weather forecasting, climate modeling, and greenhouse gas studies. These instruments will provide more accurate, detailed global observations of weather and atmospheric parameters that will, in turn, improve the accuracy and quality of weather forecasts. A satellite-based instrument is cost-effective because it can provide continuous global measurements, eliminating isolated yet costly weather balloon releases. Aqua, launched from Vandenberg Air Force Base in California (Figure 2), carries six state-of-the-art instruments that measure various water vapor parameters: (1) AIRS, which measures atmospheric temperature and humidity, land and sea surface temperatures, cloud properties, and radiative energy flux; (2) Advanced Microwave Sounding Unit, which measures atmospheric temperature and humidity during both cloudy and cloud-free periods; (3) Advanced Microwave Scanning Radiometer, which measures cloud properties, radiative energy flux, precipitation rates, land surface wetness, sea ice, snow cover, sea surface temperature, and wind fields; (4) Clouds and the Earth's Radiant Energy System, which measures radiative energy flux; (5) Humidity Sounder for Brazil, which measures atmospheric humidity by using a passive scanning microwave radiometer; and (6) Moderate Resolution Imaging Spectroradiometer, which measures cloud properties, radiative energy flux, aerosol properties, land cover and land use change, vegetation dynamics, land surface temperature, fire occurrence, volcanic effects, sea surface temperature, ocean color, snow cover, atmospheric temperature and humidity, and sea ice. The data-gathering capabilities of the Aqua instruments will provide an unprecedented view of atmosphere-land interactions (Figure 3). The availability of more frequent, more accurate global measurements of important atmospheric parameters will both improve our capabilities for short-term weather forecasting and lead to a better understanding of climate variability and climate change. Simultaneous measurements of many parameters will allow scientists to study complicated forcings and feedbacks of the atmosphere, which can be

Holdridge, D. J.

2002-07-03

277

31.4GHz flux density measurements of a complete sample of sources from the 5GHz S5 survey  

Microsoft Academic Search

The complete sample of 66 radio sources whose declinations are greater than + 70 deg, and whose 5 GHz flux densities are greater than 0.5 Jy, is presently subjected to 31.4-GHz measurements. While about half of the sources have the flat radio spectra characteristic of objects having compact components that strongly radiate in the mid-cm wavelength range, another third of

B. J. Geldzahler; H. Kuehr

1983-01-01

278

Potential evaporation trends over land between 1983-2008: driven by radiative or turbulent fluxes?  

NASA Astrophysics Data System (ADS)

We model the Penman potential evaporation (PE) over all land areas of the globe for the 25-year period 1983-2008, relying on radiation transfer models (RTMs) for the shortwave and longwave fluxes. Penman's PE is determined by two factors: available energy for evaporation and ground to atmosphere vapour transfer. Input to the PE model and RTMs comprises satellite cloud and aerosol data, as well as data from reanalyses. PE is closely linked to pan evaporation, whose trends have sparked controversy in the community, since the factors responsible for the observed pan evaporation trends are not determined with consensus. Our particular interest is the temporal evolution of PE, and the provided insight to the observed trends of pan evaporation. We examine the interannual trends of PE and various related physical quantities, such as net solar flux, net longwave flux, water vapour saturation deficit and wind speed. Our findings are the following: Global warming has led to a larger water vapour saturation deficit. Global dimming/brightening cycles in the last 25 years slightly increased the available energy for evaporation. PE trends seem to follow closely the trends of energy availability and not the trends of the atmospheric capability for vapour transfer, almost everywhere on the globe, with trends in the Northern hemisphere significantly larger than in the Southern. These results support the hypothesis that secular changes in the radiation fluxes, and not vapour transfer considerations, are responsible for potential evaporation trends.

Matsoukas, C.; Benas, N.; Hatzianastassiou, N.; Pavlakis, K. G.; Kanakidou, M.; Vardavas, I.

2011-04-01

279

On climate response to changes in the cosmic ray flux and radiative budget  

Microsoft Academic Search

We examine the results linking cosmic ray flux (CRF) variations to global\\u000aclimate change. We then proceed to study various periods over which there are\\u000aestimates for the radiative forcing, temperature change and CRF variations\\u000arelative to today. These include the Phanerozoic as a whole, the Cretaceous,\\u000athe Eocene, the Last Glacial Maximum, the 20th century, as well as the

Nir J. Shaviv

2004-01-01

280

How representative are instantaneous evaporative fraction measurements of daytime fluxes?  

NASA Astrophysics Data System (ADS)

Sun-synchronous optical and thermal remote sensing is a promising technique to provide instantaneous ET (evapotranspiration) estimates during satellite overpass. The common approach to extrapolate the instantaneous estimates to values for daily or longer periods relies on the assumption that the EF (evaporative fraction, defined as the ratio of latent heat flux to surface available energy) remains nearly constant during daytime. However, there is still no consensus on the validity of the self-preservation of the EF. We use FLUXNET (a global network of eddy covariance stations) measurements to examine this self-preservation, and the conditions under which it can hold. It is found that the instantaneous EF could represent daytime EF under clear sky conditions, especially between 11:00 and 14:00 LT (local time) for all stations. However, the results show that the EF is more variable during cloudy sky conditions, so that an increase in cloud cover results in an increase in the variability of the EF during daytime.

Peng, J.; Borsche, M.; Liu, Y.; Loew, A.

2013-10-01

281

Wide Range Neutron Flux Measuring Channel for Aerospace Application  

NASA Astrophysics Data System (ADS)

The use of classical techniques for neutron flux measurements in nuclear reactors involves the switching between several detection chains as the power grows up to 10 decades. In space applications where mass and size constraints are of key significance, such volume of hardware represents a clear disadvantage. Instead of requiring different instruments for each reactor operating range (start-up, ramping-up, and nominal power), a single instrument chain should be desirable. A Wide Range Neutron Detector (WRND) system, combining a classic pulse Counting Channel with a Campbell's theorem based Fluctuation Channel can be implemented for the monitoring and control of a space nuclear reactor. Such an instrument will allow for a reduction in the complexity of space-based nuclear instrumentation and control systems. In this presentation we will discuss the criteria and tradeoffs involved in the development of such a system. We will focus particularly on the characteristics of the System On Chip (SOC) and the DSP board used to implement this instrument.

Cibils, R. M.; Busto, A.; Gonella, J. L.; Martinez, R.; Chielens, A. J.; Otero, J. M.; Nuñez, M.; Tropea, S. E.

2008-01-01

282

How representative are instantaneous evaporative fraction measurements for daytime fluxes?  

NASA Astrophysics Data System (ADS)

Sun synchronous optical remote sensing is a promising technique to provide instantaneous ET (Evapotranspiration) estimates during satellite overpass. The common approach to extrapolate the instantaneous estimates to values for daily or longer periods relies on the assumption that the EF (Evaporative Fraction, defined as the ratio of latent heat flux to surface available energy) remains nearly constant during daytime. However, there is still no consensus on the validity of the self preservation of EF. We used FLUXNET (a global network of eddy covariance stations) measurements to examine this self preservation, and the conditions under which it can hold. It is found here that the instantaneous EF could represent daytime EF under clear-sky conditions especially between 11:00 and 14:00 LT for all the stations. However, the EF is more unstable during cloudy skies. The increase in cloud cover would result in the increase in the variability of EF during daytime. Future works will focus on the evaluation of this EF constant assumption using real remote sensing data over different surface and climate conditions.

Peng, J.; Borsche, M.; Liu, Y.; Loew, A.

2013-02-01

283

Calculation of thermal fluxes of plasma torch reradiation under the action of laser radiation on a condensed target  

SciTech Connect

The problem of laser deposition with allowance for thermal radiation transport inside and outside the laser torch is considered in a multigroup approximation. The energy fluxes of laser torch thermal radiation onto a target in the far and near zones are calculated as functions of time and the character of the exposure. It is shown that absorption of thermal fluxes in the substrate and target in the course of laser deposition results in their substantial heating. The possibility of diagnosing thermal radiation fluxes from the laser torch by using photodetectors is demonstrated.

Rudenko, V. V. [Russian Federation Ministry of Defense, 12th Central Scientific Research Institute (Russian Federation)

2010-12-15

284

Calculation of thermal fluxes of plasma torch reradiation under the action of laser radiation on a condensed target  

NASA Astrophysics Data System (ADS)

The problem of laser deposition with allowance for thermal radiation transport inside and outside the laser torch is considered in a multigroup approximation. The energy fluxes of laser torch thermal radiation onto a target in the far and near zones are calculated as functions of time and the character of the exposure. It is shown that absorption of thermal fluxes in the substrate and target in the course of laser deposition results in their substantial heating. The possibility of diagnosing thermal radiation fluxes from the laser torch by using photodetectors is demonstrated.

Rudenko, V. V.

2010-12-01

285

Year-to-year variability of components of Earth's radiation budget according to satellite measurement data  

Microsoft Academic Search

The year-to-year variability computed on satellite measurements with scanning radiometers carried by polar orbit satellites were analyzed. Solar-synchronous orbits carried out measurements over the same territory twice each day. The data wre reduced to mean monthly values of the fluxes of outgoing short and long-wave radiation. The analysis of year-to-year variability was based on mean monthly values of the radiation

G. K. Marchuk; K. Y. Kondratyev; O. A. Avaste; V. V. Kozoderov; O. Y. Kyarner

1985-01-01

286

Ionized metal flux fraction measurements in HiPIMS discharges  

NASA Astrophysics Data System (ADS)

Using a biased quartz crystal microbalance in combination with a gridded electrode, the ionized metal flux fraction in a high power impulse magnetron sputtering (HiPIMS) discharge operated with a titanium target has been investigated. The average discharge power was controlled by varying three different parameters; initial target voltage, pulse width and pulse frequency. The average discharge power was varied from 0.3 to 1.3 kW and irrespective of the power control method used an associated decrease in the flux fraction (from 50% to 30%) was observed. The mechanisms responsible for this decrease in the time-averaged flux fraction of metal ions are discussed.

Poolcharuansin, P.; Bowes, M.; Petty, T. J.; Bradley, J. W.

2012-08-01

287

Radiation Transmission Measurements for a Lightweight Fabric  

SciTech Connect

Radiation Shield Technologies has developed a lightweight fabric, shown in Fig. 1, with radiation shielding properties for X ray, gamma ray and beta particle emissions in the range of energies relevant to clinical and Homeland Security applications. Detailed measurements were done to measure the shielding properties of this material against the spectra of standard radionuclides and x-ray generators. The mass attenuation coefficients were calculated using LLNL cross section data, a 3-D photon transport code, elemental weight fractions and the measured density of the fabric.

Friedman, H; Singh, M S; DeMeo, R F

2003-01-17

288

Radiation measurements for solar energy applications  

Microsoft Academic Search

The results of radiation measurements made over the tropics and the arid and semi-arid subtropics of the world using ground based and satellite borne sensors are summarized. It is shown that solar energy of the order of 7 kWh\\/sq m is received daily at stations in the arid regions, with durations of sunshine exceeding 3,600 hours a year. Diffuse radiation

A. Mani

1977-01-01

289

Spatially averaged heat flux and convergence measurements at the ARM regional flux experiment.  

National Technical Information Service (NTIS)

Cloud formation and its relation to climate change is the greatest weakness in current numerical climate models. Surface heat flux in some cases causes clouds to form and in other to dissipate and the differences between these cases are subtle enough to m...

W. Porch F. Barnes M. Buchwald W. Clements D. Cooper

1991-01-01

290

Testing loss mechanisms capable of rapidly depleting relativistic electron flux in the Earth's outer radiation belt  

NASA Astrophysics Data System (ADS)

We investigate how relativistic electrons are lost from the Earth's magnetosphere in order to better understand the dynamic variability of the radiation belts. We identify 52 events where the >2 MeV electron flux at geostationary orbit decreases rapidly and use a superposed epoch analysis of multispacecraft data to characterize the accompanying solar wind and geomagnetic conditions and examine the relevance of potential loss mechanisms. The results show that the flux decrease events follow a common sequence. The electron flux is reduced first in the dusk sector concurrent with the stretching of the magnetic field to a more tail-like configuration. The extreme stretching at dusk is caused by the formation of a partial ring current driven by changing solar wind conditions. We investigate three possible causes of the ensuing flux decrease: adiabatic electron motion in response to the changing magnetic field topology, drift out the magnetopause boundary, and precipitation into the atmosphere. The analysis reveals that the flux depletion is likely due to enhanced precipitation into the atmosphere, but the exact cause of the enhanced precipitation is still uncertain.

Green, J. C.; Onsager, T. G.; O'Brien, T. P.; Baker, D. N.

2004-12-01

291

Effects of tropospheric aerosols on radiative flux calculations at UV and visible wavelengths  

SciTech Connect

The surface fluxes in the wavelength range 175 to 735nm have been calculated for an atmosphere which contains a uniformly mixed aerosol layer of thickness 1km at the earth`s surface. Two different aerosol types were considered, a rural aerosol, and an urban aerosol. The visibility range for the aerosol layers was 95 to 15 km. Surface flux ratios (15km/95km) were in agreement with previously published results for the rural aerosol layer to within about 2%. The surface flux ratios vary from 7 to 14% for the rural aerosol layer and from 13 to 23% for the urban aerosol layer over the wavelength range. A tropospheric radiative forcing of about 1.3% of the total tropospheric flux was determined for the 95km to 15km visibility change in the rural aerosol layer, indicating the potential of tropospheric feedback effects on the surface flux changes. This effect was found to be negligible for the urban aerosol layer. Stratospheric layer heating rate changes due to visibility changes in either the rural or urban aerosol layer were found to be negligible.

Grossman, A.S.; Grant, K.E.

1994-08-01

292

Airborne aerosol flux measurements with eddy correlation above the ocean in a coastal environment  

Microsoft Academic Search

This work is a first pilot study of particle eddy correlation flux measurements from an aircraft using a condensation particle counter. The study reports aerosol flux measurements from an airplane conducted at approximately 33m altitude above the ocean in the coastal region of Monterey Bay. The systematic and random uncertainties of such measurements are evaluated. Covariance was calculated for 200s

G. Buzorius; J. Kalogiros; V. Varutbangkul

2006-01-01

293

A Problem with Flux Chamber Measurements of Biogenic Sulfur Emissions.  

National Technical Information Service (NTIS)

Problems associated with identifying and quantifying factors that influence liquid-phase controlled evolution of hydrogen sulfide and organic sulfides through the air-water interface are briefly reviewed. It was found that at present flux chamber measurem...

D. R. Hitchcock

1979-01-01

294

Mass Flux Measurements of Arsenic in Groundwater (Battelle Conference)  

EPA Science Inventory

Concentration trends of arsenic are typically used to evaluate the performance of remediation efforts designed to mitigate arsenic contamination in groundwater. A complementary approach would be to track changes in mass flux of the contaminant through the subsurface, for exampl...

295

Flux tubes in the solar wind from Cluster measurements  

NASA Astrophysics Data System (ADS)

Recent studies of solar wind turbulence suggest that tangential discontinuities in the interplanetary medium can introduce significant intermittency and these discontinuities may be a natural manifestation of flux-tube-like structures in the solar wind. Because the existence of these flux tubes can affect our understanding of the solar wind MHD turbulence, it is necessary that we verify their existence and are able to identify them individually. Using the magnetic field data from FGM instrument onboard Cluster spacecraft, we examine the existence of flux tubes in the solar wind. Cluster/FGM has a high time resolution of magnetic field data and the orbits of Cluster also traverse through various dynamic regions, including the solar wind, Earth's magnetosheath and magnetotail, making Cluster's dataset ideal for studying the differences between, for example, solar wind turbulence and those inside the magnetosphere (e.g. turbulence in plasma sheet). Using a recent data analysis by Li, [2007a,b], we show that flux tubes exist in the solar wind, but not inside Earth's magnetotial. The existence of flux-tube-like structures in the solar wind implies that current studies of solar wind MHD turbulence must be carefully re-examined because these flux tubes will inneviatablly cause intermittency and affect turbulence power spectrum.

Li, G.; Lee, E.; Parks, G.

2007-12-01

296

Measurement of photon flux with a miniature gas ionization chamber in a Material Testing Reactor  

NASA Astrophysics Data System (ADS)

Nuclear heating measurements in Material Testing Reactors (MTR) are crucial for the design of the experimental devices and the prediction of the temperature of the hosted samples. Nuclear heating in MTR materials (except fuel) is mainly due to the energy deposition by the photon flux. Therefore, the photon flux is a key input parameter for the computer codes which simulate nuclear heating and temperature reached by samples/devices under irradiation. In the Jules Horowitz MTR under construction at the CEA Cadarache, the maximal expected nuclear heating levels will be about 15 to 18 W g?1 and it will be necessary to assess this parameter with the best accuracy. An experiment was performed at the OSIRIS reactor to combine neutron flux, photon flux and nuclear heating measurements to improve the knowledge of the nuclear heating in MTR. There are few appropriate sensors for selective measurement of the photon flux in MTR even if studies and developments are ongoing. An experiment, called CARMEN-1, was conducted at the OSIRIS MTR and we used in particular a gas ionization chamber based on miniature fission chamber design to measure the photon flux. In this paper, we detail Monte-Carlo simulations to analyze the photon fluxes with ionization chamber measurements and we compare the photon flux calculations to the nuclear heating measurements. These results show a good accordance between photon flux measurements and nuclear heating measurement and allow improving the knowledge of these parameters.

Fourmentel, D.; Filliatre, P.; Villard, J. F.; Lyoussi, A.; Reynard-Carette, C.; Carcreff, H.

2013-10-01

297

Exploiting diurnal variations to evaluate the ISCCP-FD flux calculations and radiative-flux-analysis-processed surface observations from BSRN, ARM, and SURFRAD  

NASA Astrophysics Data System (ADS)

Using a meteorological similarity comparison method (MSCM), we performed a mutual and simultaneous evaluation of the surface radiative flux datasets from the International Satellite Cloud Climatology Project-FD and the new radiative-flux-analysis-processed surface observations (RFA-PSO). For downward shortwave (SW), diffuse (Dif), and direct (Dir) fluxes, matching cloud fraction (CF) reduces the flux difference between FD and RFA-PSO by up to a factor of 2. Decreasing the aerosol optical depth values used in the FD calculations accounts for much of the remaining difference. For downward longwave (LW) flux, matching either surface air temperature or CF reduces the flux difference to nearly zero. For the total downward SW diurnal variations, there is excellent agreement for both clear and cloudy sky, but less good agreement for the Dif and Dir components. The latter agree much better for clear sky when the FD aerosol optical depth is reduced and for cloudy sky when matching CF and cloud optical depth jointly. For LW diurnal variations, the agreement is best for clear sky, but FD has a larger amplitude by 3-7 W/m2 for cloudy sky because of differing sensitivities to cirrus and low clouds in the two datasets. These results confirm that the source of the FD surface flux uncertainty of ˜10-15 W/m2 is the input quantities, not the radiative transfer model. An important limitation of the RFA-PSO cloud parameters (not the fluxes) is the inhomogeneous diurnal sampling and the retrieval difficulties with broken clouds (SW) and cirrus clouds (LW).

Zhang, Yuanchong; Long, Charles N.; Rossow, William B.; Dutton, Ellsworth G.

2010-08-01

298

Measurement of the cosmic-ray antiproton flux and a search for an antihelium  

SciTech Connect

A balloon-borne instrument has measured the cosmic-ray antiproton flux between 130 and 320 MeV and searched for antihelium between 130 and 370 MeV per nuclear. These particles were selected from the background of normal-matter cosmic rays by combining a selective trigger with a detailed spark chamber visualization of each recorded event. Antiprotons are identified by their characteristic annihilatin radiation. Residue from background processes meeting the selection criteria is small. The observed 14 antiprotons yield a measured differential flux of 1.7 +- 0.5 x 10/sup -4/ antiprotons m/sup -2/ sr/sup -1/ s/sup -1/ MeV/sup -1/ at the top of the atmosphere. The corresponding antiproton/proton ratio is 2.2 +- 0.6 x 10/sup -4/,, only slightly smaller than the ratio observed by other experiments at higher energies. Thus the antiprotons have a spectral shape similar to the protons, at least down to about 100 MeV. The expected flux of these particles can be calculated under the assumption that they were created by collisions of high-energy cosmic rays with the interstellar gas. Calculations using the standard leaky box model for propagation in the Galaxy predict a flux two orders of magnitude smaller than observed. A small low-energy flux is predicted due to a kinematic suppression of the production of low-energy antiprotons. The discrepancy between calculatons and experiment may be evidence that cosmic-ray protons have passed through substantially more than 5 g cm/sup -2/ of material during their lifetime. In addition, the combined results from this experiment and previous ones may be evidence for stochastic, energy-changing processes in interstellar space which act upon the secondary antiprotons after their creation. The search for cosmic-ray antihelium sets a 95% confidence level upper limit on the He/H ratio of 2.2 x 10/sup -5/.

Buffington, A.; Schindler, S.M.; Pennypacker, C.R.

1981-09-15

299

A comparison of six methods for measuring soil-surface carbon dioxide fluxes  

Microsoft Academic Search

Measurements of soil-surface CO2 fluxes are important for characterizing the carbon budget of boreal forests because these fluxes can be the second largest component of the budget. Several methods for measuring soil-surface CO2 fluxes are available: (1) closed-dynamic-chamber systems, (2) closed-static-chamber systems, (3) open-chamber systems, and (4) eddy covariance systems. This paper presents a field comparison of six individual systems

J. M. Norman; C. J. Kucharik; S. T. Gower; D. D. Baldocchi; P. M. Crill; M. Rayment; K. Savage; R. G. Striegl

1997-01-01

300

Effects of heat and water vapor transport on eddy covariance measurement of CO2 fluxes  

Microsoft Academic Search

Flux densities of carbon dioxide were measured over an arid, vegetation-free surface by eddy covariance techniques and by a heat budget-profile method, in which CO2 concentration gradients were specified in terms of mixing ratios. This method showed negligible fluxes of CO2, consistent with the bareness of the experimental site, whereas the eddy covariance measurements indicated large downward fluxes of CO2.

R. Leuning; O. T. Denmead; A. R. G. Lang; E. Ohtaki

1982-01-01

301

Calculation of thermal fluxes of plasma torch reradiation under the action of laser radiation on a condensed target  

Microsoft Academic Search

The problem of laser deposition with allowance for thermal radiation transport inside and outside the laser torch is considered\\u000a in a multigroup approximation. The energy fluxes of laser torch thermal radiation onto a target in the far and near zones\\u000a are calculated as functions of time and the character of the exposure. It is shown that absorption of thermal fluxes

V. V. Rudenko

2010-01-01

302

MEASUREMENT AND ANALYSIS OF CIRCUMSOLAR RADIATION  

SciTech Connect

The purpose of this project is to provide measurements and analyses of the solar and circumsolar radiation for application to solar energy systems that employ lenses or mirrors to concentrate the incident sunlight. Circumsolar radiation results from the scattering of direct sunlight through small angles by atmospheric aerosols (e.g., dust, water-droplets or ice crystals in thin clouds). Concentrating solar energy systems will typically collect all of the direct solar radiation (that originating from the disk of the sun) plus some fraction of the circumsolar radiation. The exact fraction depends upon many factors, but primarily upon the angular size (field-of-view) of the receiver. A knowledge of the circumsolar radiation is then one factor in predicting or evaluating the performance of concentrating systems. The project employs unique instrument systems (called Circumsolar Telescopes) that were designed and fabricated at LBL. The basic measurements are (1) the "circumsolar scan", the brightness of the sun and circumsolar region as a function of angular distance from the center of the sun and (2) the usual "normal incidence" measurement of a pyrheliometer. Both measurements are made for the entire solar spectrum, and (via colored filters) for eight essentially contiguous wavelength bands. Thus the measurements are applicable to systems in which the receiver is essentially wavelength-insensitive (e.g., central receiver) and to wavelength-sensitive systems (e.g., concentrating photovoltaics). A secondary purpose of the project is to relate the data to the atmospheric processes that attenuate the solar radiation available to terrestrial solar energy systems.

Grether, Donald; Evans, David; Hunt, Arlon; Wahlig, Michael

1980-10-01

303

Beyond Flux-limited Diffusion: Parallel Algorithms for Multidimensional Radiation Hydrodynamics  

NASA Astrophysics Data System (ADS)

This paper presents a new code for performing multidimensional radiation hydrodynamic (RHD) simulations on parallel computers involving anisotropic radiation fields and nonequilibrium effects. The radiation evolution modules described here encapsulate the physics provided by the serial algorithm of Stone et al. but add new functionality both with regard to physics and numerics. In detailing our method, we have documented both the analytic and discrete forms of the radiation moment solution and the variable tensor Eddington factor (VTEF) closure term. We have described three different methods for computing a short-characteristic formal solution to the transfer equation, from which our VTEF closure term is derived. Two of these techniques include time dependence, a primary physics enhancement of the method not present in the Stone algorithm. An additional physics modification is the adoption of a matter-radiation coupling scheme which is particularly robust for nonequilibrium problems and which also reduces the operations cost of our radiation moment solution. Two key numerical components of our implementation are highlighted: the biconjugate gradient linear system solver, written for general use on massively parallel computers, and our techniques for parallelizing both the radiation moment solution and the transfer solution. Additionally, we present a suite of test problems with a much broader scope than that covered in the Stone work; new tests include nonequilibrium Marshak waves, two-dimensional ``shadow'' tests showing the one-sided illumination of an opaque cloud, and full RHD+VTEF calculations of radiating shocks. We use the results of these tests to assess the virtues and vices of the method as currently implemented, and we identify a key area in which the method may be improved. We conclude that radiation moment solutions closed with variable tensor Eddington factors show a qualitative improvement over results obtained with flux-limited diffusion, and further that this approach has a bright future in the context of parallel RHD simulations in astrophysics.

Hayes, John C.; Norman, Michael L.

2003-07-01

304

Measurements and Phenomenological Modeling of Magnetic FluxBuildup in Spheromak Plasmas  

SciTech Connect

Internal magnetic field measurements and high-speed imaging at the Sustained Spheromak Physics Experiment (SSPX) [E. B. Hooper, L. D. Pearlstein, R. H. Bulmer, Nucl. Fusion 39, 863 (1999)] are used to study spheromak formation and field buildup. The measurements are analyzed in the context of a phenomenological model of magnetic helicity based on the topological constraint of minimum helicity in the open flux before reconnecting and linking closed flux. Two stages are analyzed: (1) the initial spheromak formation, i. e. when all flux surfaces are initially open and reconnect to form open and closed flux surfaces, and (2) the stepwise increase of closed flux when operating the gun on a new mode that can apply a train of high-current pulses to the plasma. In the first stage, large kinks in the open flux surfaces are observed in the high-speed images taken shortly after plasma breakdown, and coincide with large magnetic asymmetries recorded in a fixed insertable magnetic probe that spans the flux conserver radius. Closed flux (in the toroidal average sense) appears shortly after this. This stage is also investigated using resistive magnetohydrodynamic simulations. In the second stage, a time lag in response between open and closed flux surfaces after each current pulse is interpreted as the time for the open flux to build helicity, before transferring it through reconnection to the closed flux. Large asymmetries are seen during these events, which then relax to a slowly decaying spheromak before the next pulse.

Romero-Talamas, C A; Hooper, E B; Jayakumar, R; McLean, H S; Wood, R D; Moller, J M

2007-12-14

305

Radiation damage measurements in room temperature semiconductor radiation detectors  

Microsoft Academic Search

The literature of radiation damage measurements on cadmium zinc telluride (CZT), cadmium telluride (CT), and mercuric iodide (HgIâ) is reviewed and in the case of CZT supplemented by new alpha particle data. CZT strip detectors exposed to intermediate energy (1.3 MeV) proton fluences exhibit increased interstrip leakage after 10¹° p\\/cm² and significant bulk leakage after 10¹² p\\/cm². CZT exposed to

Larry A. Franks; R. W. Olsen; R. B. James; B. A. Brunett; D. S. Walsh; B. L. Doyle; G. Vizkelethy; J. I. Trombka

1998-01-01

306

Radiation damage measurements in room-temperature semiconductor radiation detectors  

Microsoft Academic Search

The literature of radiation damage measurements on cadmium zinc telluride (CZT), cadmium telluride (CT), and mercuric iodide (HgI2) is reviewed and in the case of CZT supplemented by new alpha particle data. CZT strip detectors exposed to intermediate energy (1.3MeV) proton fluences exhibit increased interstrip leakage after 1010 p\\/cm2 and significant bulk leakage after 1012 p\\/cm2. CZT exposed to 200MeV

L. A. Franks; B. A. Brunett; R. W. Olsen; D. S. Walsh; G. Vizkelethy; J. I. Trombka; B. L. Doyle; R. B. James

1999-01-01

307

Comparison of measurements from satellite radiation budget instruments  

NASA Astrophysics Data System (ADS)

Successive radiometers have been flown on spacecraft for measurement of the radiation budget of the Earth and to date have provided data sets which overlap in time over a 25-year period. Together these data sets cover two cycles of any decadal oscillation and are useful for climate research. However, before multiple data sets can be used, it is necessary first to establish precisions and relative biases of the data sets. Although these instruments were all calibrated with great care, inevitably there are differences between the instruments. Also, instruments change while in orbit due to degradation of optical elements and changes of the detectors. A number of studies have compared measurements between pairs of radiometers in order to establish these differences. In this paper we compile these results and by use of a bar chart demonstrate the traceability of calibration of satellite radiation budget instruments over these two decades. Using this compilation the differences are computed for any two instruments listed. The instruments considered here include the ERBE scanning and nonscanning radiometers, ScaRaB I and II, and the CERES instruments aboard the TRMM, Terra, and Aqua spacecraft. These results are a prerequisite to use of multiple data sets for long-term studies of climate process. The largest biases are between the ERBS scanning and non-scanning radiometers, which at the "top of the atmosphere" differ by 5.4 W m-2 for shortwave fluxes and by 5.8 W m-2 for daytime longwave fluxes. The standard deviations of the biases, which define how well the data sets can be connected, are less than 1 W m-2 for longwave and between 1 and 2 W m-2 for shortwave fluxes.

Smith, G. Louis; Szewczyk, Z. Peter; Rutan, David A.; Lee, Robert B.

2006-02-01

308

On the Relationship Between High Speed Solar Wind Streams and Radiation Belt Electron Fluxes  

NASA Astrophysics Data System (ADS)

Both past and recent research results indicate that solar wind speed has a close connection to radiation belt electron fluxes [e.g., Paulikas and Blake, 1979; Reeves et al., 2011]: a higher solar wind speed is often associated with a higher level of radiation electron fluxes. But the relationship can be very complex [Reeves et al., 2011]. The study presented here provides further corroboration of this viewpoint by emphasizing the importance of a global perspective and time history. We find that all the events during years 2010 and 2011 where the >0.8 MeV integral electron flux exceeds 10^5 particles/cm^2/sr/s (pfu) at GEO orbit are associated with the high speed streams (HSS) following the onset of the Stream Interaction Region (SIR), with most of them belonging to the long-lasting Corotating Interaction Region (CIR). Our preliminary results indicate that during HSS events, a maximum speed of 700 km/s and above is a sufficient but not necessary condition for the > 0.8 MeV electron flux to reach 10^5 pfu. But in the exception cases of HSS events where the electron flux level exceeds the 10^5 pfu value but the maximum solar wind speed is less than 700 km/s, a prior impact can be noted either from a CME or a transient SIR within 3-4 days before the arrival of the HSS - stressing the importance of time history. Through superposed epoch analysis and studies providing comparisons with the CME events and the HSS events where the flux level fails to reach the 10^5 pfu, we will present the quantitative assessment of behaviors and relationships of various quantities, such as the time it takes to reach the flux threshold value from the stream interface and its dependence on different physical parameters (e.g., duration of the HSS event, its maximum or average of the solar wind speed, IMF Bz, Kp). The ultimate goal is to apply what is derived to space weather forecasting.

Zheng, Y.

2011-12-01

309

Remote Measurement of Heat Flux from Power Plant Cooling Lakes  

SciTech Connect

Laboratory experiments have demonstrated a correlation between the rate of heat loss q? from an experimental fluid to the air above and the standard deviation ? of the thermal variability in images of the fluid surface. These experimental results imply that q? can be derived directly from thermal imagery by computing ?. This paper analyses thermal imagery collected over two power plant cooling lakes to determine if the same relationship exists. Turbulent boundary layer theory predicts a linear relationship between q? and ? when both forced (wind driven) and free (buoyancy driven) convection are present. Datasets derived from ground- and helicopter-based imagery collections had correlation coefficients between ? and q? of 0.45 and 0.76, respectively. Values of q? computed from a function of ? and friction velocity u* derived from turbulent boundary layer theory had higher correlations with measured values of q? (0.84 and 0.89). This research may be applicable to the problem of calculating losses of heat from the ocean to the atmosphere during high-latitude cold-air outbreaks because it does not require the information typically needed to compute sensible, evaporative, and thermal radiation energy losses to the atmosphere.

Garrett, A.; Kurzeja, R.; Villa-Aleman, E.; Bollinger, J.

2013-01-01

310

Radiation and the Energy Balance: The Role of Radiation.  

National Technical Information Service (NTIS)

The role of radiation, cloud radiation interactions in the climate, and radiation processes in climate change are discussed. The geometrical constraints, calibration issues, and time sampling issues of measuring radiation fluxes, done from space, are cons...

R. Kandel

1991-01-01

311

Flux density measurements and peculiarities of radio emission of pulsars at 102 and 111 MHz  

Microsoft Academic Search

At present time more than 1000 pulsars are discovered. But flux density and energy measurements were basically obtained at frequencies 400, 610 and 1400 MHz. For detail consideration of pulsar spectra and its connection with pulsar parameters the multifrequency measurements of the flux densities in all radio waves are required. At frequency about 100 MHz maximum of radio emission is

O. I. Malov

2000-01-01

312

Eddy correlation measurements of the air\\/sea flux of dimethylsulfide over the North Pacific Ocean  

Microsoft Academic Search

Shipboard measurements of air\\/sea fluxes and sea surface concentrations of dimethylsulfide (DMS) were made over the tropical and midlatitude North Pacific Ocean. Atmospheric pressure chemical ionization mass spectrometry was used to measure DMS levels in ambient air and in air equilibrated with surface seawater drawn from a depth of 5 m. Air\\/sea fluxes were obtained using eddy covariance. Corrections and

C. A. Marandino; W. J. De Bruyn; S. D. Miller; E. S. Saltzman

2007-01-01

313

FLUX MEASUREMENTS OF OZONE AND NITRIC ACID AT COASTAL AND MID-CONTINENTAL SITES  

EPA Science Inventory

A system for measuring the turbulent fluxes of ozone, nitric acid, and other gases was operated at two sites in 1994. hese direct measurements of fluxes are for comparison with those calculated for National Dry Deposition Network sites using an inferential model approach. zone fl...

314

Study on methodology of LED's luminous flux measurement with integrating sphere  

Microsoft Academic Search

Errors are introduced when using traditional methods for measuring the total luminous flux of LEDs since an LED is quite different from traditional light sources in terms of physical size, flux level, spectrum and spatial distribution. This paper uses commercial lighting simulation software named Tracepro to simulate the self-absorption effect when using traditional integrating sphere methods to measure the total

Mu-Qing Liu; Xiao-Li Zhou; Wen-Yi Li; Yu-Yang Chen; Wan-Lu Zhang

2008-01-01

315

Growing season total gaseous mercury (TGM) flux measurements over an Acer rubrum L. stand  

Microsoft Academic Search

Relaxed eddy accumulation (REA) measurements of the total gaseous mercury (TGM) flux measurements were taken over a deciduous forest predominantly composed of Red Maple (Acer rubrum L.) during the growing season of 2004 and the second half of the growing season of 2005. The magnitudes of the flux estimates were in the range of published results from other micrometeorological mercury

Jesse O. Bash; David R. Miller

2009-01-01

316

Solar Actinic Flux Spectroradiometry: A Technique for Measuring Photolysis Frequencies in the Atmosphere  

Microsoft Academic Search

A spectroradiometer has been developed for direct measurement of the solar actinic UV flux (scalar intensity) and determination of photolysis frequencies in the atmosphere. The instrument is based on a scanning double monochromator with an entrance optic that exhibits an isotropic angular response over a solid angle of 2 sr. Actinic flux spectra are measured at a resolution of 1

Andreas Hofzumahaus; Alexander Kraus; Martin Müeller

1999-01-01

317

Measurement of 8B Solar Neutrino Flux and Energy Spectrum at Super-Kamiokande  

Microsoft Academic Search

The latest Super-Kamiokande measurement of 8B solar neutrino flux and recoil electron energy spectrum are presented. The highlights of our results are the day vs night flux asymmetry, which differs from zero at the 1.3 sigma level, and the energy spectrum measurement, which shows no significant distortion compared to the BP98 standard solar model.

Gene Guillian

2001-01-01

318

Parameterizing daytime downward longwave radiation in two Korean regional flux monitoring network sites  

NASA Astrophysics Data System (ADS)

Daytime downward longwave radiation (Rld) in clear sky and all sky conditions was estimated by various well-known physical or empirical models at two Korean regional flux monitoring network (KoFlux) sites which have not been included in previously published studies for Rld models' performance. The Brunt (1932) model performed the best clear sky Rld estimations at the KoFlux sites. The Maykut and Church (1973) model performed the best all sky Rld estimations at the KoFlux sites where the bias and root mean square error (RMSE) were 3.4 and 26.6 W m-2 at the Gwangneung site and 0.3 and 32.4 W m-2 at the Haenam site, respectively. Newly proposed global Rld model by Abramowitz et al. (2012) showed reasonable Rld estimations for the all sky conditions. While selected Rld models showed the reliable estimations under clear and all sky conditions, the systematic and random errors were still observed in this study. These errors were mostly caused by relatively simple estimations of the cloud cover fraction. More validation and calibration efforts should be conducted in a range of field conditions including different climatic regions and land cover types for better understanding of the model performance with uncertainties.

Choi, Minha

2013-01-01

319

The effect of cumulus cloud field anisotropy on solar radiative fluxes and atmospheric heating rates  

NASA Astrophysics Data System (ADS)

The effect of fair-weather cumulus cloud field anisotropy on domain average surface fluxes and atmospheric heating profiles was studied. Causes of anisotropy were investigated using a large-eddy simulation (LES) model. Cloud formation under a variety of environmental conditions was simulated and the degree of anisotropy in the output fields was calculated. Wind shear was found to be the single greatest factor in the development of both vertically tilted and horizontally stretched cloud structures. A stochastic field generation algorithm was used to produce twenty three-dimensional liquid water content fields based on the statistical properties of the LES cloud scenes. Progressively greater degrees of tilt and stretching were imposed on each of these scenes, so that an ensemble of scenes were produced for each level of distortion. The resulting scenes were used as input to a three-dimensional Monte Carlo model. Domain-average transmission, reflection, and absorption of broadband solar radiation were computed for each scene along with the average heating rate profile. Both tilt and horizontal stretching were found to significantly affect calculated fluxes, with the amount and sign of flux differences depending strongly on sun position relative to cloud distortion geometry. For nearly all solar geometries, domain-averaged fluxes and atmospheric heating rate profiles calculated using the Independent Pixel Approximation differed substantially from the corresponding three-dimensional Monte Carlo results.

Hinkelman, Laura M.

320

A measurement of the greenhouse radiation associated with CCl4  

NASA Astrophysics Data System (ADS)

One of the gases which potentially can interfere with the remote sensing of gases of military interest is carbon tetrachloride (CCL4). Carbon tetrachloride is also a strong greenhouse gas with a global warming potential of 4,000. Ground-based, thermal emission measurements of the cold, clear sky have been made showing the v3 fundamental emission band of carbon tetrachloride (CCL4) which is located in the 786-806 cm-1 region. A spectrum of the non-CCl4 background emission features has been simulated using the FASCD3P line-by-line radiation code with measured radiosonde parameters of pressure, temperature and humidity. The simulated spectrum has been used to extract the CCl4 thermal emission band from the atmospheric emission spectrum. Troposhperic CCl4 mixing ratios of 120+/-20 in 1995 and 135+/-10 pptv in 2003 were determined from these measurements. In addition, the downward long-wave flux associated with the v3 emission band of CCl4 measured at the surface has been estimated to be 0.046 W/m2 +/- 17%. This flux is about one third and one fifth of that corresponding to the chlorofluorocarbons CFC-11 and CFC-12, respectively.

Evans, Wayne F. J.; Ferguson, Chris J.; Puckrin, Eldon

2004-12-01

321

Radio frequency resonator structure and diagnostic measurements for a laboratory simulation of Auroral Kilometric Radiation  

SciTech Connect

Auroral Kilometric Radiation is emitted from regions of depleted plasma density in the Earth's polar magnetosphere. The radiation frequency is close to the local electron cyclotron frequency, polarized in the X-mode with an efficiency of {approx}1%, with power up to 1 GW. Kinetic analysis of the instability in the descending auroral flux indicated that the phenomena scaled with the cyclotron frequency. Therefore, an experimental reproduction of the auroral geometry has been created scaled to laboratory dimensions by raising the radiation frequency to the microwave range. The experiment transports a 75-85 keV electron beam through a region of increasing magnetic flux density, with a mirror ratio of up to 30. The experiments measured the mode, spectrum, power, and conversion efficiency of the emitted radiation as a function of the mirror ratio in two resonance regimes, with frequencies of 4.42 and 11.7 GHz. The microwave diagnostics and measurements will be presented in this paper.

Ronald, K.; Speirs, D. C.; McConville, S. L.; Phelps, A. D. R.; Robertson, C. W.; Whyte, C. G.; He, W.; Gillespie, K. M.; Cross, A. W. [Scottish Universities Physics Alliance and Department of Physics, John Anderson Building, 107 Rottenrow, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Bingham, R. [Scottish Universities Physics Alliance and Department of Physics, John Anderson Building, 107 Rottenrow, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Space Science and Technology Department, Science and Technology Facility Council, Rutherford Appleton Laboratory, Didcot OX11 0QX (United Kingdom)

2008-05-15

322

Atmospheric Radiation Measurement Program facilities newsletter, October 2000.  

SciTech Connect

Energy Balance Bowen Ratio System--Estimates of surface energy fluxes are a primary product of the data collection systems at the ARM SGP CART site. Surface fluxes tell researchers a great deal about the effects of interactions between the sun's energy and Earth. Surface fluxes of latent and sensible heat can be estimated by measuring temperature and relative humidity gradients across a vertical distance. Sensible heat is what we feel coming from a warm sidewalk or a metal car door; it can be measured with a thermometer. Latent heat, on the other hand, is released or absorbed during transformations such as the freezing of water into ice or the evaporation of morning dew from a lawn. Such a transformation is referred to as a ''phase change,'' the conversion of a substance among its solid, liquid, and vapor phases. Phase change is an important aspect of our climate. Earth's water cycle abounds with phase changes: rain falls and evaporates, changing from liquid to vapor; the water vapor in the air condenses to form clouds, changing from a gas into a liquid cloud droplet, and eventually falls to Earth's surface as rain or snow; snow falls and melts to liquid or sublimes directly to water vapor. This cyclic process has no end. Surface vegetation and land use play extremely important roles in surface energy fluxes. Plants absorb and reflect solar radiation and also take up water and expel water vapor. The type of plant material, its stage of growth, and its color determine whether and to what extent the surface and air can couple and exchange energy.

Sisterson, D. L.

2000-11-09

323

MSL-RAD Radiation Environment Measurements  

NASA Astrophysics Data System (ADS)

We present results from the Radiation Assessment Detector (RAD) obtained during MSL's cruise to Mars and during the first 150 sols after Curiosity's successful landing. RAD is designed to measure the energetic particle environment, which consists of Galactic Cosmic Rays (GCRs), Solar Energetic Particles (SEPs), and the secondary particles created by nuclear interactions of primary GCRs in shielding. During cruise, RAD was asymmetrically shielded inside the spacecraft. On the surface, RAD is shielded by the atmosphere, and the radiation dose rate is seen to vary slightly as the column depth of the atmosphere varies on a diurnal cycle. RAD's cruise measurements are a unique data set that provide a reasonable simulation of what might be encountered by a human crew headed for Mars or for some other destination in deep space. RAD successfully operated for 220 days of the 253 day journey to Mars. RAD has also operated stably on the surface of Mars, returning the first detailed radiation data from the surface of another planet. The data from the surface are also highly relevant for planning future crewed missions. We will present results for radiation dose and dose equivalent (the quantity most directly related to human health risk) obtained with both cruise and surface data. Dose and dose equivalent are dominated by the continuous GCR radiation, but five significant SEP events were seen during cruise and will be discussed.

Zeitlin, Cary; Hassler, Donald; Wimmer-Schweingruber, Robert; Boehm, Eckart; Boettcher, Stephan; Brinza, David; Burmeister, Soenke; Cucinotta, Francis; Ehresmann, Bent; Guo, Jingnan; Koehler, Jan; Martin, Cesar; Posner, Arik; Rafkin, Scot; Reitz, Guenther; MSL Science Team

2013-04-01

324

Preliminary investigation of changes in x-ray multilayer optics subjected to high radiation flux  

SciTech Connect

A variety of metal multilayers was exposed to high x-ray flux using Sandia National Laboratories' PROTO II machine in the gas puff mode. Fluxes incident on the multilayers above 700 MW/cm/sup 2/ in total radiation, in nominal 20 ns pulses, were realized. The neon hydrogen- and helium-like resonance lines were used to probe the x-ray reflectivity properties of the multilayers as they underwent change of state during the heating pulse. A fluorescer-fiber optic-streak camera system was used to monitor the changes in x-ray reflectivity as a function of time and irradiance. Preliminary results are presented for a W/C multilayer. Work in progress to model the experiment is discussed. 13 refs., 4 figs.

Hockaday, M.P.; Blake, R.L.; Grosso, J.S.; Selph, M.M.; Klein, M.M.; Matuska, W. Jr.; Palmer, M.A.; Liefeld, R.J.

1985-01-01

325

Power stability of laser radiation measurement device  

NASA Astrophysics Data System (ADS)

The automated device for determining the power stability of cw laser beams pursuant to the requirements of the International Standard ISO 11554 has been created. Using laser radiation intensity measurements in relative units the calculation of mean power values, standard deviations, maximum and minimum readings, power stability and power drift is carried out. The measurements for medium-term (1 min) and long-term (60 min) stability are carried out.

Zhdanovskii, Vladimir A.; Snopko, Valerii N.

2002-02-01

326

Evaluation of sensible heat fluxes derived from Large Aperture Scintillometer measurements over irrigated and dryland cotton during BEAREX08  

NASA Astrophysics Data System (ADS)

The path integrating capabilities of scintillometer over heterogeneous landscapes makes it a powerful tool for validating satellite-based evapotranspiration (ET) maps. Numerous studies have evaluated the accuracy of sensible heat fluxes (H) derived from Large Aperture Scintillometer (LAS) measurements using eddy covariance (EC) measurements. EC systems have the energy balance closure problem (Rn-H-LE-G?0) up to 20 percent. For that reason we chose to evaluate the accuracy of the LAS-based ET fluxes against lysimeter data. Data used in this study was collected during the Bushland Evapotranspiration and Agricultural Remote Sensing Experiment 2008 (BEAREX08). The BEAREX08 was conducted at the USDA-ARS Conservation and Production Research Laboratory (CPRL) in Bushland [350 11' N, 1020 06' W; 1,170 m elevation MSL] located in the semi-arid Southern High Plains of Texas, USA during the 2008 summer cropping season. The CPRL is equipped with four large (3 x 3 x 2.5 m) monolithic lysimeters, with each lysimeter located in the center of 210 x 225 m fields arranged in a block pattern. One LAS was deployed across two dryland lysimeter fields (designated as NW and SW) and another on two irrigated lysimeter fields (designated as NE and SE), and all four fields were planted to cotton. The structure parameter of the refractive index of air was monitored at a 1-min interval and averaged for 15-minute periods between 10 July and 30 August, synchronized with weather station and lysimeter measurements. In addition, net radiation (Rn) and soil heat fluxes (G) were measured in all four lysimeter fields. Sensible heat fluxes (H) were derived from LAS measurements using a heat flux source area function and estimated ET fluxes as a residual from the energy balance were compared against lysimeter data. Trends in the LAS-based ET fluxes closely followed those in the observed data. However, LAS-based ET fluxes were over predicted by 10-35%. Differences between lysimeter- and LAS-based ET estimates over dryland cotton may be partly due to non-uniform vegetation growth on the NW and SW lysimeter fields. Overall, results indicate that the LAS is a promising tool for estimating ET fluxes.

Gowda, P.; Hartogensis, O.; Howell, T.; Scanlon, B.

2009-09-01

327

Disjunct eddy accumulation flux measurements of individual VOCs from an urban environment  

NASA Astrophysics Data System (ADS)

As part of the MILAGRO-2006 study a flux tower was deployed at urban Mexico City to measure turbulent fluxes of trace gases. Fluxes of individual volatile organic compounds (VOCs) were measured using a disjunct eddy accumulation (DEA) sampler with ionization detector/gas chromatography (GC-FID) analysis. The DEA method partitions the air into two reservoirs based on the magnitude and direction of the vertical wind speed. The VOCs concentrations in both reservoirs are analyzed and used to determine the fluxes with the vertical wind velocities. Although this method is not as precise as other micrometeorological techniques, such as the eddy covariance method, it provides the ability to directly measure the fluxes of an extended number of individual species using off-line sensors without relying on similarity scaling or empirical parameters. According to our knowledge these measurements constitute the first time that the DEA method was applied in an urban environment. A comparison of the DEA fluxes of selected aromatic and olefinic species measured in parallel by the more accurate eddy covariance and disjunct eddy covariance techniques coupled with fast-response analytical sensors evidenced a flux under-prediction by the DEA method. However, this under-prediction was consistent and constant for the species compared, allowing an analysis of the DEA fluxes in terms of relative magnitudes and ratios. It was found that fluxes of alkane species were the dominant VOCs fluxes, which is consistent with ambient concentration measurements and the local emissions inventory. Among the top 20 mean VOCs fluxes measured during daytime, 11 corresponded to alkanes, followed by 5 aromatics, 2 olefins, 1 alkyne and 1 oxygenated.

Velasco, Erik; Pressley, Shelley; Grivicke, Rasa; Allwine, Eugene; Jobson, B. Tom; Westberg, Hal; Molina, Luisa T.; Lamb, Brian

2010-05-01

328

Aerosol Fluxes over Amazon Rain Forest Measured with the Eddy Covariance Method  

NASA Astrophysics Data System (ADS)

We present measurements of vertical aerosol fluxes over the Amazon carried out on top of K34, a 50 meter high tower in the Cuieiras Reserve about 50 km north of Manaus in northern Brazil. The turbulent fluxes were measured with the eddy covariance method. The covariance of vertical wind speed from a sonic anemometer Gill Windmaster and total aerosol number concentration from a condensation particle counter (CPC) TSI 3010 provided the total number flux (diameter >0.01 ?m). The covariance of vertical wind speed and size resolved number concentrations from an optical particle counter (OPC) Grimm 1.109 provided size resolved number fluxes in 15 bins from 0.25 ?m to 2.5 ?m diameter. Additionally fluxes of CO2 and H2O were derived from Li-7500 observations. The observational period, from early March to early August, includes both wet and dry season. OPC fluxes generally show net aerosol deposition both during wet and dry season with the largest downward fluxes during midday. CPC fluxes show different patterns in wet and dry season. During dry season, when number concentrations are higher, downward fluxes clearly dominate. In the wet season however, when number concentrations are lower, our data indicates that upward and downward fluxes are quite evenly distributed during course of a day. On average there is a peak in upward flux during late morning and another peak during the afternoon. Since the OPC fluxes in the same time show net deposition, there is an indication of net source of primary aerosol particles with diameters between 10 and 250 nm emitted from the rain forest. Future data analysis will hopefully shed light on origin and formation mechanism of these particles and thus provide a deeper insight in the rain forest - atmosphere interactions. The aerosol flux measurements were carried out as a part of the AMAZE project in collaboration with University of Sao Paulo, Brazil, and financial support was provided by Swedish International Development Cooperation Agency (SIDA).

Ahlm, L.; Nilsson, E. D.; Krejci, R.; Mårtensson, E. M.; Vogt, M.; Artaxo, P.

2008-12-01

329

SAMPEX - A Synoptic View of Earths Electron Radiation Belts: South Pole Energetic Fluxes from HILT  

NSDL National Science Digital Library

The Solar Anomalous and Magnetospheric Particle Explorer, SAMPEX, measures fluxes of energetic particles from the sun, the Earths magnetosphere, and cosmic ray sources over a broad range of energies. The four instruments aboard SAMPEX are the Low-Energy Ion Analyzer (LEICA), The Heavy Ion Large Telescope (HILT), The Mass Spectrometer Telescope (MAST), and the Proton-Electron Telescope (PET).

Oneil, Pamela; Baker, Dan; Blake, J.; Callis, Linwood; Kanekal, S.; Klecker, Berndt

1995-01-01

330

SAMPEX - A Synoptic View of Earths Electron Radiation Belts: South Pole Energetic Fluxes from PET  

NSDL National Science Digital Library

The Solar Anomalous and Magnetospheric Particle Explorer, SAMPEX, measures fluxes of energetic particles from the sun, the Earths magnetosphere, and cosmic ray sources over a broad range of energies. The four instruments aboard SAMPEX are the Low-Energy Ion Analyzer (LEICA), The Heavy Ion Large Telescope (HILT), The Mass Spectrometer Telescope (MAST), and the Proton-Electron Telescope (PET).

Oneil, Pamela; Baker, Dan; Blake, J.; Callis, Linwood; Kanekal, S.; Klecker, Berndt

1995-01-01

331

SAMPEX - A Synoptic View of Earths Electron Radiation Belts: North Pole Energetic Fluxes from PET  

NSDL National Science Digital Library

The Solar Anomalous and Magnetospheric Particle Explorer, SAMPEX, measures fluxes of energetic particles from the sun, the Earths magnetosphere, and cosmic ray sources over a broad range of energies. The four instruments aboard SAMPEX are the Low-Energy Ion Analyzer (LEICA), The Heavy Ion Large Telescope (HILT), The Mass Spectrometer Telescope (MAST), and the Proton-Electron Telescope (PET).

Oneil, Pamela; Baker, Dan; Blake, J.; Callis, Linwood; Kanekal, S.; Klecker, Berndt

1995-01-01

332

SAMPEX - A Synoptic View of Earths Electron Radiation Belts: North Pole Energetic Fluxes from HILT  

NSDL National Science Digital Library

The Solar Anomalous and Magnetospheric Particle Explorer, SAMPEX, measures fluxes of energetic particles from the sun, the Earths magnetosphere, and cosmic ray sources over a broad range of energies. The four instruments aboard SAMPEX are the Low-Energy Ion Analyzer (LEICA), The Heavy Ion Large Telescope (HILT), The Mass Spectrometer Telescope (MAST), and the Proton-Electron Telescope (PET).

Oneil, Pamela; Baker, Dan; Blake, J.; Callis, Linwood; Kanekal, S.; Klecker, Berndt

1995-01-01

333

Atmospheric Radiation Measurement Program facilities newsletter, October 2000  

Microsoft Academic Search

Energy Balance Bowen Ratio System--Estimates of surface energy fluxes are a primary product of the data collection systems at the ARM SGP CART site. Surface fluxes tell researchers a great deal about the effects of interactions between the sun's energy and Earth. Surface fluxes of latent and sensible heat can be estimated by measuring temperature and relative humidity gradients across

Sisterson

2000-01-01

334

Advances in upscaling of eddy covariance measurements of carbon and water fluxes  

NASA Astrophysics Data System (ADS)

Eddy covariance flux towers provide continuous measurements of ecosystem-level net exchange of carbon, water, energy, and other trace gases between land surface and the atmosphere. The upscaling of flux observations from towers to broad regions provides a new and independent approach for quantifying these fluxes over regions, continents, or the globe. The seven contributions of this special section reflect the most recent advances in the upscaling of fluxes from towers to these broad regions. The section mainly stems from presentations at the recent North American Carbon Program (NACP), FLUXNET, and AGU meetings. These studies focus on different aspects of upscaling: (1) assessing the representativeness of flux networks; (2) upscaling fluxes from towers to broad spatial scales; (3) examining the magnitude, distribution, and interannual variability of fluxes over regions, continents, or the globe; and (4) evaluating the impacts of spatial heterogeneity and parameter variability on flux estimates. Collectively, this special issue provides a timely update on upscaling science and also generates gridded flux data that can be used for model evaluations. Future upscaling studies are expected to advance toward incorporating the impacts of disturbance on ecosystem carbon dynamics, quantifying uncertainties associated with gridded flux estimates, and comparing various upscaling methods and the resulting gridded flux fields.

Xiao, Jingfeng; Chen, Jiquan; Davis, Kenneth J.; Reichstein, Markus

2012-03-01

335

Radiative transfer retrievals for accurate UV-spectroscopic measurements of volcanic SO2 emissions  

Microsoft Academic Search

There is widespread use of passive remote sensing techniques to quantify trace gas column densities in volcanic plumes utilizing scattered sunlight as a light source. Examples include passive DOAS (ground-based or from satellite platforms), COSPEC, and the SO2 camera. In order to calculate trace gas concentrations or volcanic emission fluxes, knowledge about the optical path of the measured radiation through

C. Kern; T. Deutschmann; L. Vogel; M. Wöhrbach; T. Wagner; U. Platt

2009-01-01

336

METHOD AND APPARATUS FOR MEASURING RADIATION  

DOEpatents

A chemical dosimeter for measuring the progress of a radiation-induced oxidation-reduction reaction is described. The dosimeter comprises a container filled with an aqueous chemical oxidation-reduction system which reacts quantitatively to the radiation. An anode of the group consisting of antimony and tungsten and a cathode of the group consisting of gold and platnium are inserted into the system. Means are provided to stir the system and a potential sensing device is connected across the anode and cathode to detect voltage changes. (AEC)

Reeder, S.D.

1962-04-17

337

Diurnal Variations of Energetic Particle Radiation Dose Measured by the Mars Science Laboratory Radiation Assessment Detector  

NASA Astrophysics Data System (ADS)

The Radiation Assessment Detector (RAD) on board the Mars Science Laboratory (MSL) rover Curiosity has collected data on the interplanetary radiation environment during cruise from Earth to Mars and at the surface of Mars since its landing in August 2012. RAD's particle detection capabilities are achieved with a solid-state detector (SSD) stack (A, B, C), a CsI(Tl) scintillator (D), and a plastic scintillator (E) for neutron detection. The D and E detectors are surrounded by an anticoincidence shield (F), also made of plastic scintillator. All scintillators are optically coupled to silicon diodes which convert scintillation light to electrons. RAD is capable of measuring both Galactic Cosmic Rays (GCRs) thought to be produced by supernovae outside the heliosphere and Solar Energetic Particles (SEPs). GCRs are relativistic particles (100 MeV/nuc to >10 GeV/nuc) composed of roughly 89% protons, 10% alpha particles (He), and 1% heavier nuclei [1]. Because of their high energies and continuous nature, GCRs are the dominant source of background radiation at the Martian surface, and are responsible for the production of secondary particles (notably neutrons) via complex interactions in the atmosphere and regolith. SEPs are produced by coronal mass ejections. These intermittent storms are most likely to occur near solar maximum and typical fluxes are dominated by protons with energies lower than 100 MeV/nuc. Unlike the GCR flux, the SEP flux can vary by five or more orders of magnitude over timescales of a day. Even under a constant flux of energetic particle radiation at the top of the atmosphere, the radiation dose at the surface should vary as a function of surface elevation [2]. This variation is directly related to the change in the shielding provided by the total atmospheric mass column, which is to a very good approximation directly related to surface pressure. Thus, the flux of primary energetic particles should increase with altitude, all other things being equal. At present, MSL has been at a nearly constant altitude of ~-4.4 km MOLA so that no elevation-induced changes are expected and none have been observed. However, any process that changes the column mass of atmosphere should change the dose at the surface. On Mars there are two major processes that substantially change column atmospheric mass. The first is the seasonal condensation cycle during which ~25% of the dominant atmospheric constituent (CO2) condenses onto the winter pole. This seasonal signal is very strong and has been observed by surface pressure measurements from the Viking Landers up through MSL [3,4]. The second major process is related to the thermal tide. The direct heating of the Martian atmosphere by the Sun produces global scale waves that redistribute mass [5]. The two most dominant tidal modes are the diurnal and semidiurnal tide. Together, the thermal tide can produce a variation of 10-15% over a Martian day (sol). Here, we report on the dose measured by the RAD E detector and the variation of this dose over the diurnal cycle. Further, we show that the variation in the E dose rate is very likely due to the variation of column mass, as measured by the pressure sensor on the Rover Environmental Monitoring Station (REMS), driven by the thermal tide. While changes in dose were expected from changes in altitude or season, the discovery of a diurnal variation was not anticipated, although it should have been reasonably expected in hindsight.

Rafkin, Scot; Zeitlin, Cary; Ehresmann, Bent; Köhler, Jan; Guo, Jingnan; Kahanpää, Henrik; Hassler, Don; -Gomez, Javier E.; Wimmer-Schweingruber, Robert; Brinza, David; Böttcher, Stephan; Böhm, Eckhard; Burmeister, Sonka; Martin, Cesar; Müller-Mellin, Robert; Appel, Jan; Posner, Arik; Reitz, Gunter; Kharytonov, Aliksandr; Cucinotta, Francis

2013-04-01

338

Measuring light-emitting diodes with a scanner for radiant flux and colour characterization  

NASA Astrophysics Data System (ADS)

Due to the performance requirements of displays and lighting applications, there is a great need to measure the radiant flux and colour of light-emitting diodes (LEDs) simultaneously in a high throughput format. We evaluate the feasibility of obtaining reliable colour and radiant flux values of LEDs with a low-cost office flatbed document scanner under factory settings versus conventional measurements. Colour purity was evaluated against a spectrometer and a digital camera, while radiant flux was evaluated against photodiodes. Scanner colour rendition of red, green and yellow LEDs was of variable quality. The scanner showed better correlation to conventional radiant flux measurements, with linear least-squares agreement between 0.934 and 0.985. A scanner represents a low cost and high throughput means of evaluating LEDs with simultaneous measures of both electroluminescent flux and emission colour with operational time.

Naquin, Clint A.; Hasan, Omar A.; Liou, Wei-Ting; Lee, Roxanne R.; Halbert, Armand J.; Phung, Anthony T.; Liu, An-Ting; Bursa, Emin J.; Shen, Yulong; Taylor, David W.; Slinker, Jason D.

2013-05-01

339

Measured carbon dioxide emissions from Oldoinyo Lengai and the skewed distribution of passive volcanic fluxes  

Microsoft Academic Search

Airborne measurements of CO2 released from Oldoinyo Lengai, the only carbonatite-erupting volcano in the world, reveal a CO2 flux of 0.055 × 1012 mol\\/yr. This flux is substantially smaller than that of Mount Etna (1 × 1012 mol\\/yr), which accounts for over half of the global carbon flux attributed to subaerial volcanoes (1 2 × 1012 mol\\/yr). We propose that

Susan L. Brantley; Kevin W. Koepenick

1995-01-01

340

Design Studies for Flux and Polarization Measurements of Photons and Positrons for SLAC Proposal E166: An experiment to test polarized positron production in the FFTB (LCC-0107)  

SciTech Connect

We present results from design studies carried out to investigate measurements of the flux, spectrum and polarization of undulator photons for SLAC Proposal E166. A transmission Compton polarimeter is considered for measuring the photon circular polarization. We also present results for measuring the flux and spectrum of positrons produced by the undulator photons in an 0.5X{sub 0} Titanium target. And we present some considerations for use of a transmission Compton polarimeter to measure the circular polarization of bremsstrahlung photons emitted by the polarized positrons in a thin radiator.

Woods, M

2003-10-02

341

Impact of the summer 2004 Alaska fires on top of the atmosphere clear-sky radiation fluxes  

Microsoft Academic Search

In this study we estimate the radiative impact of wildfires in Alaska during the record wildfire season of 2004 by integrating model simulations and satellite observations of the top of the atmosphere (TOA) radiative fluxes and aerosol optical depth. We compare results for the summer of 2004 to results for the summer of 2000 when fire activity in the boreal

G. G. Pfister; P. G. Hess; L. K. Emmons; P. J. Rasch; F. M. Vitt

2008-01-01

342

Solar wind driven radiation belt response functions at 100-min time scales using SAMPEX orbit-averaged electron fluxes  

Microsoft Academic Search

Characterizations of radiation belt dynamics using linear prediction filters (LPFs) were first published by Nagai (1988) and Baker et al. (1990). These studies focused primarily on short-term predictions of daily-averaged radiation fluxes at geostationary orbit using global magnetospheric indices and the speed of the so la r wind impinging on the Earth's magnetosphere. Using solar wind data from the NSSDC

D. Baker; J. Rigler; D. Vassiliadis

2002-01-01

343

Improved radon-flux-measurement system for uranium-tailings pile measurement  

SciTech Connect

The Pacific Northwest Laboratory (PNL) is developing cover technology for uranium mill tailings that will inhibit the diffusion of radon to the atmosphere. As part of this cover program, an improved radon flux measurement system has been developed. The radon measurement system is a recirculating, pressure-balanced, flow-through system that uses activated carbon at ambient temperatures to collect the radon. With the system, an area of 0.93 m/sup 2/ is sampled for periods ranging from 1 to 12 h. The activated carbon is removed from the radon trap and the collected radon is determined by counting the /sup 214/Bi daughter product. Development of the system included studies to determine the efficiency of activated carbon, relative calibration measurements and field measurements made during 1980 at the inactive tailings pile in Grand Junction, Colorado. Results of these studies are presented.

Freeman, H.D.

1981-10-01

344

Surface turbulent flux measurements over the Loess Plateau for a semi-arid climate change study  

NASA Astrophysics Data System (ADS)

In order to provide high quality data for climate change studies, the data quality of turbulent flux measurements at the station of SACOL (Semi-Arid Climate & Environment Observatory of Lanzhou University), which is located on a semi-arid grassland over the Loess Plateau in China, has been analyzed in detail. The effects of different procedures of the flux corrections on CO2, momentum, and latent and sensible heat fluxes were assessed. The result showed that coordinate rotation has a great influence on the momentum flux but little on scalar fluxes. For coordinate rotation using the planar fit method, different regression planes should be determined for different wind direction sectors due to the heterogeneous nature of the ground surface. Sonic temperature correction decreased the sensible heat flux by about 9%, while WPL correction (correction for density fluctuations) increased the latent heat flux by about 10%. WPL correction is also particularly important for CO2 fluxes. Other procedures of flux corrections, such as the time delay correction and frequency response correction, do not significantly influence the turbulent fluxes. Furthermore, quality tests on stationarity and turbulence development conditions were discussed. Parameterizations of integral turbulent characteristics (ITC) were tested and a specific parameterization scheme was provided for SACOL. The ITC test on turbulence development conditions was suggested to be applied only for the vertical velocity. The combined results of the quality tests showed that about 62%-65% of the total data were of high quality for the latent heat flux and CO2 flux, and as much as about 76% for the sensible heat flux. For the momentum flux, however, only about 35% of the data were of high quality.

Zuo, Jinqing; Huang, Jianping; Wang, Jiemin; Zhang, Wu; Bi, Jianrong; Wang, Guoyin; Li, Weijing; Fu, Peijian

2009-07-01

345

Snow temperature profiles and heat fluxes measured on the Greenland crest by an automatic weather station  

SciTech Connect

In June 1989 three automatic weather station (AWS) units were installed on the Greenland crest at the GISP2 (78.58 N, 38.46 W, 3265 m) and GRIP (78.57 N, 37.62 W, 3230 m) ice coring sites and at Kenton (72.28 N, 38.80 W, 3185 m), the air sampling site. The purpose of the AWS units is to measure the local meteorological variables, including snow temperatures at various depths, in support of ice coring studies. The AWS units measure wind speed and direction, air temperature, and relative humidity at a nominal height of 3.6 meters, air pressure at the electronics enclosure, and air temperature difference between 3.6 m and 0.5 m. The AWS units at GISP2 and GRIP also measure solar radiation, and seven snow temperatures from the surface to a depth of approximately 4 m in the snow. The data are updated at 10-minute intervals and transmitted to the ARGOS data collection system on board the NOAA series of polar-orbiting satellites. The air temperature and snow temperatures are presented as a function of time for the period from June 8, 1989 to August 31, 1990 and as tautochrones at 30-day intervals. The heat flux into the snow is determined from the daily mean snow temperature between the day after and the day before using the volumetric heat capacity of the snow assuming a snow density of 300 kg m-3. The daily mean heat flux into the snow between the highest and the lowest levels of snow temperature is presented as a function of time.

Stearns, C.R.; Weidner, G A.

1992-03-01

346

Magnetogasdynamic shock waves in a nonideal gas with heat conduction and radiation heat flux  

NASA Astrophysics Data System (ADS)

The purpose of this study is to obtain a self-similar solution of the problem of propagation of a magnetogasdynamic shock wave in a nonideal gas with heat conduction and radiation heat flux in the presence of a spatially decreasing azimuthal magnetic field strength. The initial density of the medium is assumed to be constant. The heat conduction is expressed in terms of Fourier's law, and the radiation is considered to be of a diffusion type for an optically thick gray gas model. The thermal conductivity and absorption coefficients are assumed to vary with temperature and density. The shock is assumed to be driven by a piston moving with a variable velocity. Similarity solutions are obtained, and the effects of variation of the gas nonidealness parameter and Alfven-Mach number on the flow field behind the shock are investigated.

Singh, K. K.; Nath, B.

2012-09-01

347

Developing Consistent Earth System Data Records for the Global Terrestrial Water Cycle: Focus on Shortwave and Longwave Radiative Fluxes  

NASA Astrophysics Data System (ADS)

The overall goal of the MEaSUREs activity titled: "Developing Consistent Earth System Data Records for the Global Terrestrial Water Cycle" is to develop consistent, long-term Earth System Data Records (ESDRs) for the major components of the terrestrial water cycle at a climatic time scale. The shortwave (SW) and longwave (LW) radiative fluxes at the Earth's surface determine the exchange of energy between the land and the atmosphere are the focus of this presentation. During the last two decades, significant progress has been made in assessing the Earth Radiation Balance from satellite observations. Yet, satellite based estimates differ from each other and long term satellite observations at global scale are not readily available. There is a need to utilize existing records of satellite observations and to improve currently available estimates. This paper reports on improvements introduced to an existing methodology to estimate shortwave (SW) radiative fluxes within the atmospheric system, on the development of a new inference scheme for deriving LW fluxes, the implementation of the approach with the ISCCP DX observations and improved atmospheric inputs for the period of 1983-2007, evaluation against ground observations, and comparison with independent satellite methods and numerical models. The resulting ESDRs from the entire MEaSUREs Project are intended to provide a consistent basis for estimating the mean state and variability of the land surface water cycle at a spatial scale relevant to major global river basins. MEaSUREs Project "Developing Consistent Earth System Data Records for the Global Terrestrial Water Cycle" Team Members: E. F. Wood (PI)1, T. J Bohn2, J. L Bytheway3, X. Feng4, H. Gao2, P. R.Houser4 (CO-I), C. D Kummerow3 (CO-I), D. P Lettenmaier2 (CO-I), C. Li5, Y. Ma5, R. F MacCracken4, M. Pan1, R. T Pinker5 (CO-I), A. K. Sahoo1, J. Sheffield1 1. Dept of CEE, Princeton University, Princeton, NJ, USA. 2. Dept of CEE, University of Washington, Seattle, WA, USA. 3. Dept of Atmospheric Science, Fort Collins, CO, USA. 4. Dept of Geography and GeoInformation Scie., George Mason University, Fairfax, VA, USA. 5. Dept of Meteorology, University of Maryland, College Park, MD, USA.

Pinker, R. T.; Ma, Y.; Nussbaumer, E. A.

2012-04-01

348

Measurement of wall radiation in the soft x-ray region of PDX  

SciTech Connect

A detector setup with three LN-cooled Si(Li) diodes is used to measure soft x-ray spectra (0.8 to 20 keV) emitted from the inside walls of the PDX vessel during the plasma discharge. This setup is part of a pulse-height-analysis system, which is used to measure the plasma and wall radiation simultaneously at five different radial positions. The wall and the plasma radiation are measured under different plasma conditions (e.g., OH and neutral beam heating). The wall radiation is increased very much during the neutral beam heating with an enhancement factor of at least 10 over OH wall radiation. Since we measure the plasma and the wall radiation at the same time, these measurements allow the conclusion that the wall radiation can be attributed essentially to fluorescence (line radiation, e.g., Ti-K/sub ..cap alpha../) and scattering (continuum part of the wall radiation spectrum). The fluorescence and the scattering are both caused by soft x-ray radiation flux coming from the plasma. There seems to be no need to invoke other, more exotic causes for the wall radiation (like charge particle bombardment of the wall).

Sesnic, S.; Tenney, F.H.; Bitter, M.; Hill, K.W.; von Goeler, S.

1985-01-01

349

Contribution of Soil Surface CO2 Efflux to Boreal Forest Net Ecosystem Flux: Measurements and Modeling  

NASA Astrophysics Data System (ADS)

The aims of the study are to assess the contribution of measured soil surface CO2 efflux to boreal forest net ecosystem flux and to test whether modeled component fluxes such as leaf and surface soil fluxes are consistent with the net flux measured from a tower over a forest stand. Net ecosystem flux was measured continuously in a boreal Scots pine forest in eastern Finland (62° 52'N, 30° 49'E) during the growing period in 2000. Height and diameter of trees in this 50-year-old stand ranged from 10 to 13 m and from 9 to 12 cm, respectively, for 80 % of trees. Eddy-flux measurements were made at the top of a 32-m tower, about 20 m above the canopy. Wind velocity and virtual temperature were measured with a three-axis sonic anemometer. CO2 fluctuations at 32 m were continuously monitored with a CO2 analyzer. Raw data were sampled at 10 Hz and 1/2 hr fluxes calculated. Soil surface CO2 efflux was measured on the top of a feather moss or lichen cover with an IRGA and four automated open dynamic chambers, each equipped with a PAR sensor and air temperature probe. Chambers of 19 cm diameter were made of transparent PMMA. Measurements were made twice per hr, lasting 1 min each. Periods considered in this study included both early and late season conditions, since data from the automated soil surface efflux measurements were available from May to June as well as from August to September. In this study, we aim to compare the measured soil surface CO2 efflux with simultaneously measured net ecosystem flux. The performance of the automated chambers will be tested by comparing with simultaneous measurements from a dark closed static chamber at the same site. A simple regression model, using soil surface temperature as an independent variable, will be built using the static dark chamber data from the previous years. A rough correction for the carbon uptake of moss will be made. This model could be validated later with automated measurements. To investigate further the components of the net ecosystem flux, we are planning to use a process-based model on forest ecosystem functioning to estimate flux from the canopy. Canopy structure will be described in the model using results from needle mass sampling in the same stand. The physiological responses of shoots to environmental factors such as light, temperature, and soil moisture are derived from measurements or estimates made at the site or from studies on Scots pine at a nearby site. These modeled component fluxes from tree canopies and soil surface will be compared with the measured net ecosystem flux for the sample periods.

Niinisto, S. M.; Kellomaki, S.

2001-05-01

350

Measurement of the Cosmic Ray and Neutrino-Induced Muon Flux at the Sudbury Neutrino Observatory  

SciTech Connect

Results are reported on the measurement of the atmospheric neutrino-induced muon flux at a depth of 2 kilometers below the Earth's surface from 1229 days of operation of the Sudbury Neutrino Observatory (SNO). By measuring the flux of through-going muons as a function of zenith angle, the SNO experiment can distinguish between the oscillated and un-oscillated portion of the neutrino flux. A total of 514 muon-like events are measured between -1 {le} cos {theta}{sub zenith} 0.4 in a total exposure of 2.30 x 10{sup 14} cm{sup 2} s. The measured flux normalization is 1.22 {+-} 0.09 times the Bartol three-dimensional flux prediction. This is the first measurement of the neutrino-induced flux where neutrino oscillations are minimized. The zenith distribution is consistent with previously measured atmospheric neutrino oscillation parameters. The cosmic ray muon flux at SNO with zenith angle cos {theta}{sub zenith} > 0.4 is measured to be (3.31 {+-} 0.01 (stat.) {+-} 0.09 (sys.)) x 10{sup -10} {micro}/s/cm{sup 2}.

SNO collaboration; Aharmim, B.; Ahmed, S.N.; Andersen, T.C.; Anthony, A.E.; Barros, N.; Beier, E.W.; Bellerive, A.; Beltran, B.; Bergevin, M.; Biller, S.D.; Boudjemline, K.; Boulay, M.G.; Burritt, T.H.; Cai, B.; Chan, Y.D.; Chen, M.; Chon, M.C.; Cleveland, B.T.; Cox-Mobrand, G.A.; Currat, C.A.; Dai, X.; Dalnoki-Veress, F.; Deng, H.; Detwiler, J.; Doe, P.J.; Dosanjh, R.S.; Doucas, G.; Drouin, P.-L.; Duncan, F.A.; Dunford, M.; Elliott, S.R.; Evans, H.C.; Ewan, G.T.; Farine, J.; Fergani, H.; Fleurot, F.; Ford, R.J.; Formaggio, J.A.; Gagnon, N.; Goon, J.TM.; Grant, D.R.; Guillian, E.; Habib, S.; Hahn, R.L.; Hallin, A.L.; Hallman, E.D.; Hargrove, C.K.; Harvey, P.J.; Harvey, P.J.; Heeger, K.M.; Heintzelman, W.J.; Heise, J.; Helmer, R.L.; Hemingway, R.J.; Henning, R.; Hime, A.; Howard, C.; Howe, M.A.; Huang, M.; Jamieson, B.; Jelley, N.A.; Klein, J.R.; Kos, M.; Kruger, A.; Kraus, C.; Krauss, C.B.; Kutter, T.; Kyba, C.C.M.; Lange, R.; Law, J.; Lawson, I.T.; Lesko, K.T.; Leslie, J.R.; Levine, I.; Loach, J.C.; Luoma, S.; MacLellan, R.; Majerus, S.; Mak, H.B.; Maneira, J.; Marino, A.D.; Martin, R.; McCauley, N.; McDonald, A.B.; McGee, S.; Mifflin, C.; Miller, M.L.; Monreal, B.; Monroe, J.; Noble, A.J.; Oblath, N.S.; Okada, C.E.; O?Keeffe, H.M.; Opachich, Y.; Orebi Gann, G.D.; Oser, S.M.; Ott, R.A.; Peeters, S.J.M.; Poon, A.W.P.; Prior, G.; Rielage, K.; Robertson, B.C.; Robertson, R.G.H.; Rollin, E.; Schwendener, M.H.; Secrest, J.A.; Seibert, S.R.; Simard, O.; Simpson, J.J.; Sinclair, D.; Skensved, P.; Smith, M.W.E.; Sonley, T.J.; Steiger, T.D.; Stonehill, L.C.; Tagg, N.; Tesic, G.; Tolich, N.; Tsui, T.; Van de Water, R.G.; VanDevender, B.A.; Virtue, C.J.; Waller, D.; Waltham, C.E.; Wan Chan Tseung, H.; Wark, D.L.; Watson, P.; Wendland, J.; West, N.; Wilkerson, J.F.; Wilson, J.R.; Wouters, J.M.; Wright, A.; Yeh, M.; Zhang, F.; Zuber, K.

2009-02-16

351

Measurement of the cosmic ray and neutrino-induced muon flux at the Sudbury neutrino observatory  

SciTech Connect

Results are reported on the measurement of the atmospheric neutrino-induced muon flux at a depth of 2 kilometers below the Earth's surface from 1229 days of operation of the Sudbury Neutrino Observatory (SNO). By measuring the flux of through-going muons as a function of zenith angle, the SNO experiment can distinguish between the oscillated and unoscillated portion of the neutrino flux. A total of 514 muonlike events are measured between -1{<=}cos{theta}{sub zenith}{<=}0.4 in a total exposure of 2.30x10{sup 14} cm{sup 2} s. The measured flux normalization is 1.22{+-}0.09 times the Bartol three-dimensional flux prediction. This is the first measurement of the neutrino-induced flux where neutrino oscillations are minimized. The zenith distribution is consistent with previously measured atmospheric neutrino oscillation parameters. The cosmic ray muon flux at SNO with zenith angle cos{theta}{sub zenith}>0.4 is measured to be (3.31{+-}0.01(stat){+-}0.09(sys))x10{sup -10} {mu}/s/cm{sup 2}.

Aharmim, B.; Farine, J.; Fleurot, F.; Hallman, E. D.; Krueger, A.; Luoma, S.; Schwendener, M. H.; Virtue, C. J. [Department of Physics and Astronomy, Laurentian University, Sudbury, Ontario P3E 2C6 (Canada); Ahmed, S. N.; Cai, B.; Chen, M.; Evans, H. C.; Ewan, G. T.; Guillian, E.; Harvey, P. J.; Kos, M.; Kraus, C.; Leslie, J. R.; MacLellan, R.; Mak, H. B. [Department of Physics, Queen's University, Kingston, Ontario K7L 3N6 (Canada)] (and others)

2009-07-01

352

Measurement of the cosmic ray and neutrino-induced muon flux at the Sudbury neutrino observatory  

NASA Astrophysics Data System (ADS)

Results are reported on the measurement of the atmospheric neutrino-induced muon flux at a depth of 2 kilometers below the Earth’s surface from 1229 days of operation of the Sudbury Neutrino Observatory (SNO). By measuring the flux of through-going muons as a function of zenith angle, the SNO experiment can distinguish between the oscillated and unoscillated portion of the neutrino flux. A total of 514 muonlike events are measured between -1?cos??zenith?0.4 in a total exposure of 2.30×1014cm2s. The measured flux normalization is 1.22±0.09 times the Bartol three-dimensional flux prediction. This is the first measurement of the neutrino-induced flux where neutrino oscillations are minimized. The zenith distribution is consistent with previously measured atmospheric neutrino oscillation parameters. The cosmic ray muon flux at SNO with zenith angle cos??zenith>0.4 is measured to be (3.31±0.01(stat)±0.09(sys))×10-10?/s/cm2.

Aharmim, B.; Ahmed, S. N.; Andersen, T. C.; Anthony, A. E.; Barros, N.; Beier, E. W.; Bellerive, A.; Beltran, B.; Bergevin, M.; Biller, S. D.; Boudjemline, K.; Boulay, M. G.; Burritt, T. H.; Cai, B.; Chan, Y. D.; Chen, M.; Chon, M. C.; Cleveland, B. T.; Cox-Mobrand, G. A.; Currat, C. A.; Dai, X.; Dalnoki-Veress, F.; Deng, H.; Detwiler, J.; Doe, P. J.; Dosanjh, R. S.; Doucas, G.; Drouin, P.-L.; Duncan, F. A.; Dunford, M.; Elliott, S. R.; Evans, H. C.; Ewan, G. T.; Farine, J.; Fergani, H.; Fleurot, F.; Ford, R. J.; Formaggio, J. A.; Gagnon, N.; Goon, J. T. M.; Graham, K.; Grant, D. R.; Guillian, E.; Habib, S.; Hahn, R. L.; Hallin, A. L.; Hallman, E. D.; Hargrove, C. K.; Harvey, P. J.; Hazama, R.; Heeger, K. M.; Heintzelman, W. J.; Heise, J.; Helmer, R. L.; Hemingway, R. J.; Henning, R.; Hime, A.; Howard, C.; Howe, M. A.; Huang, M.; Jamieson, B.; Jelley, N. A.; Klein, J. R.; Kos, M.; Krüger, A.; Kraus, C.; Krauss, C. B.; Kutter, T.; Kyba, C. C. M.; Lange, R.; Law, J.; Lawson, I. T.; Lesko, K. T.; Leslie, J. R.; Levine, I.; Loach, J. C.; Luoma, S.; MacLellan, R.; Majerus, S.; Mak, H. B.; Maneira, J.; Marino, A. D.; Martin, R.; McCauley, N.; McDonald, A. B.; McGee, S.; Mifflin, C.; Miller, M. L.; Monreal, B.; Monroe, J.; Noble, A. J.; Oblath, N. S.; Okada, C. E.; O'Keeffe, H. M.; Opachich, Y.; Gann, G. D. Orebi; Oser, S. M.; Ott, R. A.; Peeters, S. J. M.; Poon, A. W. P.; Prior, G.; Rielage, K.; Robertson, B. C.; Robertson, R. G. H.; Rollin, E.; Schwendener, M. H.; Secrest, J. A.; Seibert, S. R.; Simard, O.; Simpson, J. J.; Sinclair, D.; Skensved, P.; Smith, M. W. E.; Sonley, T. J.; Steiger, T. D.; Stonehill, L. C.; Tagg, N.; Teši?, G.; Tolich, N.; Tsui, T.; van de Water, R. G.; Vandevender, B. A.; Virtue, C. J.; Waller, D.; Waltham, C. E.; Tseung, H. Wan Chan; Wark, D. L.; Watson, P.; Wendland, J.; West, N.; Wilkerson, J. F.; Wilson, J. R.; Wouters, J. M.; Wright, A.; Yeh, M.; Zhang, F.; Zuber, K.

2009-07-01

353

Atmospheric Radiation Measurement program facilities newsletter, May 2002.  

SciTech Connect

Eight eddy correlation (ECOR) flux measurement systems are now deployed throughout the ARM SGP CART site. These systems are used to determine the flux (flow) of sensible heat, the flux of latent heat, and air momentum just above cropland a few hundred feet upwind of the ECOR locations. Sensible heat is energy we feel as warmth. Latent heat is the energy that evaporated water vapor measured in the atmosphere. The ECOR systems actually measure wind velocity and temperature fluctuations, water vapor, and barometric pressure. The surface flux values for sensible heat, latent heat, and momentum are calculated from these measurements.

Holdridge, D. J.

2002-06-03

354

Radiation beam calorimetric power measurement system  

DOEpatents

A radiation beam calorimetric power measurement system for measuring the average power of a beam such as a laser beam, including a calorimeter configured to operate over a wide range of coolant flow rates and being cooled by continuously flowing coolant for absorbing light from a laser beam to convert the laser beam energy into heat. The system further includes a flow meter for measuring the coolant flow in the calorimeter and a pair of thermistors for measuring the temperature difference between the coolant inputs and outputs to the calorimeter. The system also includes a microprocessor for processing the measured coolant flow rate and the measured temperature difference to determine the average power of the laser beam.

Baker, John (Livermore, CA); Collins, Leland F. (Pleasanton, CA); Kuklo, Thomas C. (Ripon, CA); Micali, James V. (Dublin, CA)

1992-01-01

355

Absolute beam flux measurement at NDCX-I using gold-melting calorimetry technique  

SciTech Connect

We report on an alternative way to measure the absolute beam flux at the NDCX-I, LBNL linear accelerator. Up to date, the beam flux is determined from the analysis of the beam-induced optical emission from a ceramic scintilator (Al-Si). The new approach is based on calorimetric technique, where energy flux is deduced from the melting dynamics of a gold foil. We estimate an average 260 kW/cm2 beam flux over 5 {micro}s, which is consistent with values provided by the other methods. Described technique can be applied to various ion species and energies.

Ni, P.A.; Bieniosek, F.M.; Lidia, S.M.; Welch, J.

2011-04-01

356

Concentrated solar-flux measurements at the IEA-SSPS solar-central-receiver power plant, Tabernas - Almeria (Spain). Final report. Technical report No. 2/82  

SciTech Connect

A flux analyzing system (F.A.S.) was installed at the central receiver system of the SSPS project to determine the relative flux distribution of the heliostat field and to measure the entire optical solar flux reflected from the heliostat field into the receiver cavity. The functional principles of the F.A.S. are described. The raw data and the evaluation of the measurements of the entire heliostat field are given, and an approach to determine the actual fluxes which hit the receiver tube bundle is presented. A method is described to qualify the performance of each heliostat using a computer code. The data of the measurements of the direct radiation are presented. (LEW)

von Tobel, G.; Schelders, C.; Real, M.

1982-01-01

357

An Analysis of Airborne Measurements of Vertical Water Vapor Flux During BOMEX  

Microsoft Academic Search

The initial analysis of the water vapor flux measurements taken onboard a NOAA DC-6 during the Barbados Oceanographic and Meteorological Experiment (BOMEX) is presented. The flux of water vapor seems to be constant in the lower subcloud layer. Day-to-day variations, as well as variations within a day are apparent in the evaporation data. Spatial variations of evaporation also seem to

B. R. Bean; R. Gilmer; R. L. Grossman; R. McGavin; C. Travis

1972-01-01

358

Nightside electron flux measurements at Mars by the Phobos-2 HARP instrument  

Microsoft Academic Search

All the available nightside electron data obtained during circular orbits at Mars from the Phobos-2 HARP instrument have been examined in detail and are summarized in this paper. An electron flux component with energies exceeding that of the unperturbed solar wind was observed inside the magnetosheath, indicating the presence of acceleration mechanism(s). The character of the electron fluxes measured in

N. Shutte; K. Gringauz; P. Király; G. Kotova; A. F. Nagy; H. Rosenbauer; K. Szegö; M. Verigin

1995-01-01

359

Flux chamber measurements of anomalous CO2 emission from the flanks of Mammoth Mountain, California  

Microsoft Academic Search

The CO2 fluxes involved in the mass mortality of large stands of timber on the flanks of Mammoth Mountain in California's Sierra Nevada were measured and spatial and temporal inhomogeneities observed. Our estimate of the integrated flux over the total area of tree-kill is on the order of 400 t day?1. Small scale spatial variability most likely reflects varying degrees

T. A. Rahn; J. E. Fessenden; M. Wahlen

1996-01-01

360

New Epstein Frame for Core Loss Measurements at High Frequencies and High Flux Densities  

Microsoft Academic Search

This paper presents a new Epstein frame capable of core loss measurements on laminations subjected to high frequencies and high flux densities. The lamination characterization at high frequencies and high flux densities is mandatory in loss calculation procedure for high speed novel designs. The new 200- turn frame is compared with the 352-turn industrial standard frame and the recently developed

Marubini J. Manyage; Pragasen Pillay

2008-01-01

361

An assessment of corrections for eddy covariance measured turbulent fluxes over snow in mountain environments  

Technology Transfer Automated Retrieval System (TEKTRAN)

Snow-covered complex terrain is an extremely important runoff generating landscape in high altitude and latitude environments, yet is often considered non-viable for eddy covariance measurements of turbulent fluxes. Turbulent flux data are useful for evaluating the coupled snow cover mass and energ...

362

Critical assessment of surface incident solar radiation observations collected by SURFRAD, USCRN and AmeriFlux networks from 1995 to 2011  

NASA Astrophysics Data System (ADS)

Surface incident solar radiation (Rs) drives weather and climate changes. Observations of Rs have been widely used as reference data to evaluate climate model simulations and satellite retrievals. However, few have studied uncertainties of Rs observations, especially long term. This paper compares Rs from 1995 to 2011 at collocated sites collected by the Surface Radiation Budget Network (SURFRAD), the U.S. Climate Reference Network (USCRN) and the AmeriFlux network. SURFRAD stations have measured separately the diffuse and direct components of Rs as well as Rs by a pyranometer, while Rs was measured by a pyranometer or a net radiometer at the USCRN and AmeriFlux sites. Rs can be calculated by summing the diffuse and direction radiation measurements. Rs measured by the summation technique was compared those measured by a pyranometer or a net radiometer at collocated sites. Agreement among these four independent Rs measurements is good with correlation coefficients higher than 0.98 and an average error (one standard deviation) of about 4% at both hourly and monthly time scales. Rs has a large spatial variability at the hourly time scale, even exceeding 100 W m-2 in ˜6 km. This spatial variability is substantially reduced at the monthly time scale. The two independent measurement systems at the SURFRAD sites agree rather well in annual variability of Rs with an average relative standard deviation error of 34%. The errors are 71% and 85% for the USCRN and AmeriFlux sites. Evidently, caution should be taken when using the Rs data collected at the USCRN and AmeriFlux sites to study annual variability of Rs.

Wang, Kaicun; Augustine, John; Dickinson, Robert E.

2012-12-01

363

Future radiation measurements in low Earth orbit  

NASA Astrophysics Data System (ADS)

The first Long Duration Exposure Facility (LDEF) mission has demonstrated the value of the LDEF concept for deep surveys of the space radiation environment. This paper will survey the types of measurements that could be done on a second LDEF mission. One of the most surprising discoveries on LDEF1 was the Be-7 that was found imbedded on the windward surface. LDEF2 could follow up on this discovery and search for evidence of other cosmogenic nuclei. Another experiment could be designed to investigate the presence of energetic heavy ions observed on LDEF1. The relative abundance of rare earths can also be used to search for evidence that cosmic rays accelerate in episodes which occur throughout their propagation in the stellar medium. Further investigations of radiation effects could also be undertaken. A second LDEF mission also offers the opportunity for new investigations such as measurements of cosmic ray differential energy spectrum to ultrahigh energies. These and other ideas will be discussed.

Adams, James H., Jr.

1992-06-01

364

Annual Southern Ocean heat flux measured for first time  

NASA Astrophysics Data System (ADS)

The Southern Ocean makes up nearly a quarter of the global ocean by surface area and plays a powerful role in regulating Earth's climate by affecting ocean and atmospheric circulation patterns. Modeled representations of the Southern Ocean, however, are plagued by uncertainty. Obtaining direct observations of Southern Ocean properties with which to confirm the modeled estimates is difficult in such hostile polar conditions. To help overcome this shortfall, the Southern Ocean Flux Station (SOFS), the first moored sensor array to ever be successfully deployed in the Southern Ocean, was set up south of Australia.

Schultz, Colin

2012-10-01

365

Latitude measurements of cosmic radiation intensity in stratosphere and at sea level on marine antarctic expeditions  

NASA Astrophysics Data System (ADS)

The correlation coefficients (W9R,x, t) for the activity minimum 1975 to 1976 were determined on the basis of: stratospheric latitude measurement; measurement of the flux of soft charged radiation and gamma radiation at sea level as a function of cutoff rigidity Rc and determination of the latitude effect for the charged and gamma radiations; checking of the geomagnetic cutoff thresholds Rc, computed using the IGRF magnetic field model; clarification of the role of the radioactive background for determining the latitude effect for low-energy particles. The design of the instrument used in cosmic ray measurements at sea level the processing of measurement data are described the results of latitude measurements of ionizing and gamma radiations at sea level are presented, latitude stratospheric measurements at the solar activity minimum 1975 to 1976 are outlined. The sea-level latitude measurements gave the flux of charged cosmic radiation and the distribution of cosmic ray intensity as a function of Rc. Comparison of the measurements made in the Northern and Southern Hemispheres in the Atlantic reveals a systematic difference in the Rc values which requires introduction of a correction.

Svirzhevskiy, N. S.

1985-11-01

366

Computation of Solar Radiative Fluxes by 1D and 3D Methods Using Cloudy Atmospheres Inferred from A-train Satellite Data  

NASA Astrophysics Data System (ADS)

This study used realistic representations of cloudy atmospheres to assess errors in solar flux estimates associated with 1D radiative transfer models. A scene construction algorithm, developed for the EarthCARE mission, was applied to CloudSat, CALIPSO and MODIS satellite data thus producing 3D cloudy atmospheres measuring 61 km wide by 14,000 km long at 1 km grid-spacing. Broadband solar fluxes and radiances were then computed by a Monte Carlo photon transfer model run in both full 3D and 1D independent column approximation modes. Results were averaged into 1,303 (50 km)2 domains. For domains with total cloud fractions A c < 0.7 top-of-atmosphere (TOA) albedos tend to be largest for 3D transfer with differences increasing with solar zenith angle. Differences are largest for A c > 0.7 and characterized by small bias yet large random errors. Regardless of A c , differences between 3D and 1D transfer rarely exceed ±30 W m-2 for net TOA and surface fluxes and ±10 W m-2 for atmospheric absorption. Horizontal fluxes through domain sides depend on A c with ˜20% of cases exceeding ±30 W m-2; the largest values occur for A c > 0.7. Conversely, heating rate differences rarely exceed ±20%. As a cursory test of TOA radiative closure, fluxes produced by the 3D model were averaged up to (20 km)2 and compared to values measured by CERES. While relatively little attention was paid to optical properties of ice crystals and surfaces, and aerosols were neglected entirely, ˜30% of the differences between 3D model estimates and measurements fall within ±10 W m-2; this is the target agreement set for EarthCARE. This, coupled with the aforementioned comparison between 3D and 1D transfer, leads to the recommendation that EarthCARE employ a 3D transport model when attempting TOA radiative closure.

Barker, H. W.; Kato, S.; Wehr, T.

2012-07-01

367

Measurement of LNAPL flux using single-well intermittent mixing tracer dilution tests.  

PubMed

The stability of subsurface Light Nonaqueous Phase Liquids (LNAPLs) is a key factor driving expectations for remedial measures at LNAPL sites. The conventional approach to resolving LNAPL stability has been to apply Darcy's Equation. This paper explores an alternative approach wherein single-well tracer dilution tests with intermittent mixing are used to resolve LNAPL stability. As a first step, an implicit solution for single-well intermittent mixing tracer dilution tests is derived. This includes key assumptions and limits on the allowable time between intermittent mixing events. Second, single-well tracer dilution tests with intermittent mixing are conducted under conditions of known LNAPL flux. This includes a laboratory sand tank study and two field tests at active LNAPL recovery wells. Results from the sand tank studies indicate that LNAPL fluxes in wells can be transformed into formation fluxes using corrections for (1) LNAPL thicknesses in the well and formation and (2) convergence of flow to the well. Using the apparent convergence factor from the sand tank experiment, the average error between the known and measured LNAPL fluxes is 4%. Results from the field studies show nearly identical known and measured LNAPL fluxes at one well. At the second well the measured fluxes appear to exceed the known value by a factor of two. Agreement between the known and measured LNAPL fluxes, within a factor of two, indicates that single-well tracer dilution tests with intermittent mixing can be a viable means of resolving LNAPL stability. PMID:22489832

Smith, Tim; Sale, Tom; Lyverse, Mark

2012-04-10

368

Methane flux, vertical gradient and mixing ratio measurements in a tropical forest  

NASA Astrophysics Data System (ADS)

Measurements of CH4 mixing ratio, vertical gradients and turbulent fluxes were carried out in a tropical forest (Reserva Biológica Cuieiras), about 60 km north of Manaus, Brazil. The methane mixing ratio and flux measurements were performed at a height of 53 m (canopy height 35 m). In addition, vertical CH4 gradients were measured within the canopy using custom made air samplers at levels of 2, 16 and 36 m above ground. The methane gradients within the canopy reveal that there is a continuous methane source at the surface. No clear evidence for aerobic methane emission from the canopy was found. The methane fluxes above the canopy are small but consistently show an upward flux with a maximum early in the morning, and the measured fluxes are in agreement with what is expected from the positive CH4 gradient in the canopy. In the morning hours, a strong canopy venting peak is observed for both CH4 and CO2, but for CO2 this peak is then superimposed by photosynthetic uptake, whereas the peak lasts longer for CH4. Monthly averaged diurnal cycles of the CH4 mixing ratio show a decrease during daytime and increase during nighttime. The magnitude of the difference in CH4 mixing ratio between day and night gradually increases throughout the wet season. The fluxes required to explain the nighttime increase are in agreement with the nighttime fluxes measured above the canopy, which implies that the CH4 increase in the nighttime boundary layer originates from local sources.

Querino, C. A. S.; Smeets, C. J. P. P.; Vigano, I.; Holzinger, R.; Moura, V.; Gatti, L. V.; Martinewski, A.; Manzi, A. O.; de Araújo, A. C.; Röckmann, T.

2011-02-01

369

Description of heat flux measurement methods used in hydrocarbon and propellant fuel fires at Sandia.  

SciTech Connect

The purpose of this report is to describe the methods commonly used to measure heat flux in fire applications at Sandia National Laboratories in both hydrocarbon (JP-8 jet fuel, diesel fuel, etc.) and propellant fires. Because these environments are very severe, many commercially available heat flux gauges do not survive the test, so alternative methods had to be developed. Specially built sensors include 'calorimeters' that use a temperature measurement to infer heat flux by use of a model (heat balance on the sensing surface) or by using an inverse heat conduction method. These specialty-built sensors are made rugged so they will survive the environment, so are not optimally designed for ease of use or accuracy. Other methods include radiometers, co-axial thermocouples, directional flame thermometers (DFTs), Sandia 'heat flux gauges', transpiration radiometers, and transverse Seebeck coefficient heat flux gauges. Typical applications are described and pros and cons of each method are listed.

Nakos, James Thomas

2010-12-01

370

Radiation Transmission Measurements for Demron Fabric  

SciTech Connect

Radiation Shield Technologies has requested a measurement survey of its Demron fabric to determine the shielding properties in the x-ray, gamma ray and beta particle emissions in the range of energies relevant to clinical and Homeland Security applications. It is important to perform a detailed measurement program in order to sort out the shielding properties of this material in light of the often-times complex spectra emitted by standard radio-nuclides and x-ray generators. Low energy portions of the spectra are shielded more easily by this fabric than are the higher energy components and a simple single-layer test can lead to misleading results. This concept of ''spectral hardening'' was investigated by measuring the transmission factors for many layers and extracting information from the slopes of the transmission curves thereby obtaining a true picture of the shielding properties of the material as a function of energy. After the initial measurement program was completed, the mass attenuation coefficients were calculated using the LLNL cross section data, TART code, RST supplied weight fractions and the measured density of the fabric. This code is used for the Monte Carlo simulation of coupled neutron-photon transport in 3-D geometry for shielding and other applications. With such a design tool, it is possible to ''tune'' the characteristics of the Demron fabric to meet the specific needs for a given radiation environment.

Friedman, H; Singh, M S

2003-01-07

371

Calcium fluxes modulate the radiation-induced bystander responses in targeted glioma and fibroblast cells.  

PubMed

Bystander responses have been reported to be a major determinant of the response of cells to radiation exposure at low doses, including those of relevance to therapy. This study investigated the role of changes in calcium levels in bystander responses leading to chromosomal damage in nonirradiated T98G glioma cells and AG01522 fibroblasts that had been either exposed to conditioned medium from irradiated cells or co-cultured with a population where a fraction of cells were individually targeted through the nucleus or cytoplasm with a precise number of microbeam helium-3 particles. After the recipient cells were treated with conditioned medium from T98G or AG01522 cells that had been irradiated through either nucleus or cytoplasm, rapid calcium fluxes were monitored in the nonirradiated recipient cells. Their characteristics were dependent on the source of the conditioned medium but had no dependence on radiation dose. When recipient cells were co-cultured with an irradiated population of either T98G or AG01522 cells, micronuclei were induced in the nonirradiated cells, but this response was eliminated by treating the cells with calcicludine (CaC), a potent blocker of Ca(2+) channels. Moreover, both the calcium fluxes and the bystander effect were inhibited when the irradiated T98G cells were treated with aminoguanidine, an inhibitor of nitric oxide synthase (NOS), and when the irradiated AG01522 cells were treated with DMSO, a scavenger of reactive oxygen species (ROS), which indicates that NO and ROS were involved in the bystander responses generated from irradiated T98G and AG01522 cells, respectively. Our findings indicate that calcium signaling may be an early response in radiation-induced bystander effects leading to chromosome damage. PMID:16953666

Shao, Chunlin; Lyng, Fiona M; Folkard, Melvyn; Prise, Kevin M

2006-09-01

372

Eddy covariance flux measurements of pollutant gases in urban Mexico City  

NASA Astrophysics Data System (ADS)

Eddy covariance (EC) flux measurements of the atmosphere/surface exchange of gases over an urban area are a direct way to improve and evaluate emissions inventories, and, in turn, to better understand urban atmospheric chemistry and the role that cities play in regional and global chemical cycles. As part of the MCMA-2003 study, we demonstrated the feasibility of using eddy covariance techniques to measure fluxes of selected volatile organic compounds (VOCs) and CO2 from a residential district of Mexico City (Velasco et al., 2005a, b). During the MILAGRO/MCMA-2006 field campaign, a second flux measurement study was conducted in a different district of Mexico City to corroborate the 2003 flux measurements, to expand the number of species measured, and to obtain additional data for evaluation of the local emissions inventory. Fluxes of CO2 and olefins were measured by the conventional EC technique using an open path CO2 sensor and a Fast Isoprene Sensor calibrated with a propylene standard. In addition, fluxes of toluene, benzene, methanol and C2-benzenes were measured using a virtual disjunct EC method with a Proton Transfer Reaction Mass Spectrometer. The flux measurements were analyzed in terms of diurnal patterns and vehicular activity and were compared with the most recent gridded local emissions inventory. In both studies, the results showed that the urban surface of Mexico City is a net source of CO2 and VOCs with significant contributions from vehicular traffic. Evaporative emissions from commercial and other anthropogenic activities were significant sources of toluene and methanol. The results show that the emissions inventory is in reasonable agreement with measured olefin and CO2 fluxes, while C2-benzenes and toluene emissions from evaporative sources are overestimated in the inventory. It appears that methanol emissions from mobile sources occur, but are not reported in the mobile emissions inventory.

Velasco, E.; Pressley, S.; Grivicke, R.; Allwine, E.; Coons, T.; Foster, W.; Jobson, B. T.; Westberg, H.; Ramos, R.; Hernández, F.; Molina, L. T.; Lamb, B.

2009-10-01

373

Eddy covariance flux measurements of pollutant gases in urban Mexico City  

NASA Astrophysics Data System (ADS)

Eddy covariance (EC) flux measurements of the atmosphere/surface exchange of gases over an urban area are a direct way to improve and evaluate emissions inventories, and, in turn, to better understand urban atmospheric chemistry and the role that cities play in regional and global chemical cycles. As part of the MCMA-2003 study, we demonstrated the feasibility of using eddy covariance techniques to measure fluxes of selected volatile organic compounds (VOCs) and CO2 from a residential district of Mexico City (Velasco et al., 2005a, b). During the MILAGRO/MCMA-2006 field campaign, a second flux measurement study was conducted in a different district of Mexico City to corroborate the 2003 flux measurements, to expand the number of species measured, and to obtain additional data for evaluation of the local emissions inventory. Fluxes of CO2 and olefins were measured by the conventional EC technique using an open path CO2 sensor and a Fast Isoprene Sensor calibrated with a propylene standard. In addition, fluxes of toluene, benzene, methanol and C2-benzenes were measured using a virtual disjunct EC method with a Proton Transfer Reaction Mass Spectrometer. The flux measurements were analyzed in terms of diurnal patterns and vehicular activity and were compared with the most recent gridded emissions inventory. In both studies, the results showed that the urban surface of Mexico City is a net source of CO2 and VOCs with significant contributions from vehicular traffic. Evaporative emissions from commercial and other anthropogenic activities were significant sources of toluene and methanol. The data show that the emissions inventory is in reasonable agreement with measured olefin and CO2 fluxes, while C2-benzenes and toluene emissions from evaporative sources are overestimated in the inventory. It appears that methanol emissions from mobile sources occur, but are not present in the mobile emissions inventory.

Velasco, E.; Pressley, S.; Grivicke, R.; Allwine, E.; Coons, T.; Foster, W.; Jobson, T.; Westberg, H.; Ramos, R.; Hernández, F.; Molina, L. T.; Lamb, B.

2009-03-01

374

Measurements of neutron fluxes in the LSM underground laboratory  

NASA Astrophysics Data System (ADS)

A good particle candidate for Cold Dark Matter (CDM) is the supersymmetric neutralino or more generally a weakly interacting massive particle (WIMP). The expected interaction rate of WIMPs with the detector medium in direct detection experiments is below 0.01 events/kg/day. This makes a good knowledge of the background conditions highly important, especially with ever increasing sensitivity of the detectors. One major component of the background is related to energetic neutrons induced by cosmic muons. However, the flux of low energy and thermal neutrons typically from spontaneous fission and (?, n) reactions in the rock surrounding underground experiments gives also valuable information about the overall environmental activity. Detailed studies carried out in the framework of the EDELWEISS experiment are presented.

Eitel, Klaus; Edelweiss Collaboration

2012-07-01

375

Bunch Length Measurements using Coherent Radiation  

SciTech Connect

The accelerating field that can be obtained in a beam-driven plasma wakefield accelerator depends on the current of the electron beam that excites the wake. In the E-167 experiment, a peak current above 10 kA will be delivered at a particle energy of 28 GeV. The bunch has a length of a few ten micrometers and several methods are used to measure its longitudinal profile. Among these, autocorrelation of coherent transition radiation (CTR) is employed. The beam passes a thin metallic foil, where it emits transition radiation. For wavelengths greater than the bunch length, this transition radiation is emitted coherently. This amplifies the long-wavelength part of the spectrum. A scanning Michelson interferometer is used to autocorrelate the CTR. However, this method requires the contribution of many bunches to build an autocorrelation trace. The measurement is influenced by the transmission characteristics of the vacuum window and beam splitter. We present here an analysis of materials, as well as possible layouts for a single shot CTR autocorrelator.

Ischebeck, Rasmus; Barnes, Christopher; Blumenfeld, Ian; Decker, Franz-Josef; Hogan, Mark; Iverson, Richard H.; Krejcik, Patrick; Siemann, Robert H.; Walz, Dieter; /SLAC; Kirby, Neil; /Stanford U., Phys. Dept.; Clayton, Chris; Huang, Chengkun; Johnson, Devon K.; Lu, Wei; Marsh, Ken; /UCLA; Deng, Suzhi; Oz, Erdem; /Southern California U.

2005-06-24

376

Scrape-off layer power flux measurements in the Tore Supra tokamak  

NASA Astrophysics Data System (ADS)

A new method to measure power flux in strongly magnetized plasmas is described, while the flaws inherent in standard Langmuir probe techniques are demonstrated. Instead of small cylindrical pins which overestimate the ion current density by several 100%, a concave probe has been developed which is immune to sheath expansion, and which inherently provides accurate measurements. A retarding field analyzer directly measures the ion component of the power flux by means of an integral method that eliminates the need to calculate the heat transmission factor. Evidence shows that strong secondary electron emission from surfaces with non-oblique magnetic field incidence angles is ubiquitous in the scrape-off layer of the Tore Supra tokamak. This results in sheath collapse, causing the power flux to be dominated by the electrons. The radially integrated power flux measured by the probes agrees well with the power convected to the limiter.

Gunn, J. P.; Dejarnac, R.; Devynck, P.; Fedorczak, N.; Fuchs, V.; Gil, C.; Ko?an, M.; Komm, M.; Kubi?, M.; Lunt, T.; Monier-Garbet, P.; Pascal, J.-Y.; Saint-Laurent, F.

2013-07-01

377

Study on methodology of LED's luminous flux measurement with integrating sphere  

NASA Astrophysics Data System (ADS)

Errors are introduced when using traditional methods for measuring the total luminous flux of LEDs since an LED is quite different from traditional light sources in terms of physical size, flux level, spectrum and spatial distribution. This paper uses commercial lighting simulation software named Tracepro to simulate the self-absorption effect when using traditional integrating sphere methods to measure the total luminous flux of LEDs and then presents a modified method for the measurement. The LED under investigation or a specially designed narrow beam standard lamp is placed on the interior wall of the sphere in our method. The results show that the measurement method presented here can lead to better precision in the evaluation of the total luminous flux of LEDs.

Liu, Mu-Qing; Zhou, Xiao-Li; Li, Wen-Yi; Chen, Yu-Yang; Zhang, Wan-Lu

2008-07-01

378

Measurements of the Solar Neutrino Flux from Super-Kamiokande{close_quote}s First 300 Days  

SciTech Connect

The first results of the solar neutrino flux measurement from Super-Kamiokande are presented. The results shown here are obtained from data taken between 31 May 1996, and 23 June 1997. Using our measurement of recoil electrons with energies above 6.5thinspthinspMeV, we infer the total flux of {sup 8}B solar neutrinos to be 2.42{plus_minus}0.06(stat){sup +0.10}{sub {minus}0.07}(syst){times}10{sup 6} thinspcm{sup {minus}2}thinsp s{sup {minus}1} . This result is consistent with the Kamiokande measurement and is 36{percent} of the flux predicted by the BP95 solar model. The flux is also measured in 1.5 month subsets and shown to be consistent with a constant rate. {copyright} {ital 1998} {ital The American Physical Society }

Fukuda, Y.; Hayakawa, T.; Ichihara, E.; Inoue, K.; Ishihara, K.; Ishino, H.; Itow, Y.; Kajita, T.; Kameda, J.; Kasuga, S.; Kobayashi, K.; Kobayashi, Y.; Koshio, Y.; Martens, K.; Miura, M.; Nakahata, M.; Nakayama, S.; Okada, A.; Oketa, M.; Okumura, K.; Ota, M.; Sakurai, N.; Shiozawa, M.; Suzuki, Y.; Takeuchi, Y.; Totsuka, Y.; Yamada, S. [Institute for Cosmic Ray Research, University of Tokyo, Tanashi, Tokyo 188-8502 (Japan); Earl, M.; Habig, A.; Hong, J.T.; Kearns, E.; Kim, S.B.; Masuzawa, M.; Messier, M.D.; Scholberg, K.; Stone, J.L.; Sulak, L.R.; Walter, C.W. [Department of Physics, Boston University, Boston, Massachusetts 02215 (United States); Goldhaber, M. [Physics Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); Barszczak, T.; Gajewski, W.; Halverson, P.G.; Hsu, J.; Kropp, W.R.; Price, L.R.; Reines, F.; Sobel, H.W.; Vagins, M.R.; Haines, T.J.; Kielczewska, D. [Department of Physics and Astronomy, University of California, Irvine, Irvine, California 92697-4575 (United States); Ganezer, K.S.; Keig, W.E. [Department of Physics, California State University, Dominguez Hills, Carson, California 90747 (United States); Ellsworth, R.W. [Department of Physics, George Mason University, Fairfax, Virginia 22030 (United States); Tasaka, S. [Department of Physics, Gifu University, Gifu, Gifu 501-1193 (Japan); Flanagan, J.W.; Kibayashi, A.; Learned, J.G.; Matsuno, S.; Stenger, V.; Takemori, D. [Department of Physics and Astronomy, University of Hawaii, Honolulu, Hawaii 96822 (United States); Ishii, T.; Kanzaki, J.; Kobayashi, T.; Nakamura, K.; Nishikawa, K.; Oyama, Y.; Sakai, A.; Sakuda, M.; Sasaki, O. [Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801 (Japan); Echigo, S.; Kohama, M.; Suzuki, A.T. [Department of Physics, Kobe University, Kobe, Hyogo 657-8501 (Japan); Haines, T.J. [Physics Division, P-23, Los Alamos National Laboratory (United States)

1998-08-01

379

The Thermal Conductivity Measurements of Solid Samples by Heat Flux Differantial Scanning Calorimetry  

NASA Astrophysics Data System (ADS)

The thermal conductivity of polyvinylchloride (PVC), polysytrene (PS) and polypropylene (PP) were measured by heat flux DSC. Our results are in good agreement with the results observed by different methods.

Kök, M.; Aydo?du, Y.

2007-04-01

380

Annual sediment flux estimates in a tidal strait using surrogate measurements  

NASA Astrophysics Data System (ADS)

Annual suspended-sediment flux estimates through Carquinez Strait (the seaward boundary of Suisun Bay, California) are provided based on surrogate measurements for advective, dispersive, and Stokes drift flux. The surrogates are landward watershed discharge, suspended-sediment concentration at one location in the Strait, and the longitudinal salinity gradient. The first two surrogates substitute for tidally averaged discharge and velocity-weighted suspended-sediment concentration in the Strait, thereby providing advective flux estimates, while Stokes drift is estimated with suspended-sediment concentration alone. Dispersive flux is estimated using the product of longitudinal salinity gradient and the root-mean-square value of velocity-weighted suspended-sediment concentration as an added surrogate variable. Cross-sectional measurements validated the use of surrogates during the monitoring period. During high freshwater flow advective and dispersive flux were in the seaward direction, while landward dispersive flux dominated and advective flux approached zero during low freshwater flow. Stokes drift flux was consistently in the landward direction. Wetter than average years led to net export from Suisun Bay, while dry years led to net sediment import. Relatively low watershed sediment fluxes to Suisun Bay contribute to net export during the wet season, while gravitational circulation in Carquinez Strait and higher suspended-sediment concentrations in San Pablo Bay (seaward end of Carquinez Strait) are responsible for the net import of sediment during the dry season. Annual predictions of suspended-sediment fluxes, using these methods, will allow for a sediment budget for Suisun Bay, which has implications for marsh restoration and nutrient/contaminant transport. These methods also provide a general framework for estimating sediment fluxes in estuarine environments, where temporal and spatial variability of transport are large.

Ganju, N.; Schoellhamer, D.

2006-08-01

381

Estimating regional methane surface fluxes: the relative importance of surface and GOSAT mole fraction measurements  

NASA Astrophysics Data System (ADS)

We use an ensemble Kalman filter (EnKF), together with the GEOS-Chem chemistry transport model, to estimate regional monthly methane (CH4) fluxes for the period June 2009-December 2010 using proxy dry-air column-averaged mole fractions of methane (XCH4) from GOSAT (Greenhouse gases Observing SATellite) and/or NOAA ESRL (Earth System Research Laboratory) and CSIRO GASLAB (Global Atmospheric Sampling Laboratory) CH4 surface mole fraction measurements. Global posterior estimates using GOSAT and/or surface measurements are between 510-516 Tg yr-1, which is less than, though within the uncertainty of, the prior global flux of 529 ± 25 Tg yr-1. We find larger differences between regional prior and posterior fluxes, with the largest changes (75 Tg yr-1) occurring in Temperate Eurasia. In non-boreal regions the error reductions for inversions using the GOSAT data are at least three times larger (up to 45%) than if only surface data are assimilated, a reflection of the greater spatial coverage of GOSAT, with the two exceptions of latitudes > 60° associated with a data filter and over Europe where the surface network adequately describes fluxes on our model spatial and temporal grid. We use CarbonTracker and GEOS-Chem XCO2 model output to investigate model error on quantifying proxy GOSAT XCH4 (involving model XCO2) and inferring methane flux estimates from surface mole fraction data and show similar resulting fluxes, with differences reflecting initial differences in the proxy value. Using a series of observing system simulation experiments (OSSEs) we characterize the posterior flux error introduced by non-uniform atmospheric sampling by GOSAT. We show that clear-sky measurements can theoretically reproduce fluxes within 5% of true values, with the exception of South Africa and Tropical South America where, due to a large seasonal cycle in the number of measurements because of clouds and aerosols, fluxes are within 17% and 19% of true fluxes, respectively. We evaluate our posterior methane fluxes by incorporating them into GEOS-Chem and sampling the model at the location and time of independent surface CH4 measurements from the AGAGE (Advanced Global Atmospheric Gases Experiment) network and column XCH4 measurements from TCCON (Total Carbon Column Observing Network). The posterior fluxes modestly improve the model agreement with AGAGE and TCCON data relative to prior fluxes, with the correlation coefficients (r2) increasing by a mean of 0.04 (range: -0.17, 0.23) and the biases decreasing by a mean of 0.4 ppb (range: -8.9, 8.4 ppb).

Fraser, A.; Palmer, P. I.; Feng, L.; Boesch, H.; Cogan, A.; Parker, R.; Dlugokencky, E. J.; Fraser, P. J.; Krummel, P. B.; Langenfelds, R. L.; O'Doherty, S.; Prinn, R. G.; Steele, L. P.; van der Schoot, M.; Weiss, R. F.

2012-12-01

382

A stochastic model for estimating groundwater and contaminant discharges from fractured rock passive flux meter measurements  

NASA Astrophysics Data System (ADS)

Estimation of water and contaminant discharges is an important hydrological problem. Fractured rock aquifers are recognized as highly complex flow and transport systems, and the fractured rock passive flux meter (FRPFM) is a recently tested device to simultaneously measure cumulative water and contaminant mass fluxes in fractures intersecting an observation well (boring). Furthermore, the FRPFM is capable of indicating orientations and directions of flow in hydraulically active ("flowing") fractures. The present work develops a discharge estimator for when FRPFM measurements of fracture fluxes in the direction perpendicular to a transect (control plane) along one or more observation wells are available. In addition, estimation uncertainty in terms of a coefficient of variation is assessed based on a Monte Carlo approach under normalized conditions. Sources of uncertainty considered are spatially random fracture trace locations, random trace lengths, and orientations as well as variability of trace average fluxes (including smooth spatial trends), variability of local fluxes within traces, and flux measurement errors. Knowledge about the trace length distribution, which is commonly not available from borehole surveys, is not required for discharge estimation. However, it does affect the uncertainty assessment, and equations for upper uncertainty bounds are given as an alternative. In agreement with general statistical inference, it is found that discharge uncertainty decreases proportionally with the number of fluxes measured. Results are validated, and an example problem illustrates practical application and performance.

Acar, Özlem; Klammler, Harald; Hatfield, Kirk; Newman, Mark A.; Annable, Michael D.; Cho, Jaehyun; Parker, Beth L.; Cherry, John A.; Pehme, Pete; Quinn, Patryk; Kroeker, Ryan

2013-03-01

383

Eddy flux and leaf-level measurements of biogenic VOC emissions from mopane woodland of Botswana  

NASA Astrophysics Data System (ADS)

Biogenic volatile organic compound (BVOC) emissions were measured in a mopane woodland near Maun, Botswana in January-February 2001 as part of SAFARI 2000. This landscape is comprised of more than 95% of one woody plant species, Colophospermum mopane (Caesalpinaceae). Mopane woodlands extend over a broad area of southern Africa. A leaf cuvette technique was used to determine the emission capacities of the major vegetation and the temperature and light dependence of the emissions. In addition, relaxed eddy accumulation (REA) measurements of BVOC fluxes were made on a flux tower, where net CO2 emissions were also measured simultaneously. Large light-dependent emissions of terpenes (mostly ?-pinene and D-limonene) were observed from the mopane woodland. The diurnal BVOC emissions were integrated and compared with the CO2 flux. Monoterpene flux exceeded 3000 ?g C m-2 h-1 during the daytime period, comparable to isoprene fluxes and much higher than terpene fluxes measured in most areas. The terpene flux constituted approximately 25% of the diurnal net carbon exchange (CO2) during the experimental period. Other BVOC emissions may also contribute to the carbon exchange.

Greenberg, J. P.; Guenther, A.; Harley, P.; Otter, L.; Veenendaal, E. M.; Hewitt, C. N.; James, A. E.; Owen, S. M.

2003-07-01

384

Cosmic Radiation Intensity Measurements Using TL Dosimeters at Various Mountain Altitudes  

NASA Astrophysics Data System (ADS)

The Earth is bombarded by cosmic radiation, a nearly isotropic flux of energetic charged particles. Their interaction with air nuclei generates a cascade of secondary particles and gamma rays. This work describes the results of measurements of cosmic radiation at various altitudes on mount Olympus using TL dosimeters (Al2O3:C). The glow curves of TLDs after external exposure have been compared to the ones obtained after beta irradiation in the laboratory. Pb-shielding was used for separation of gamma contribution from terrestrial radiation environment.

Sdrolia, Athina; Sfamba, Ioanna; Liolios, Anastasios; Kitis, Georgios

2010-01-01

385

Future radiation measurements in low Earth orbit  

NASA Astrophysics Data System (ADS)

The first Long Duration Exposure Facility (LDEF) mission has demonstrated the value of the LDEF concept for deep surveys of the space radiation environment. The kinds of measurements that could be done on a second LDEF mission are discussed. Ideas are discussed for experiments which: (1) capitalize on the discoveries from LDEF 1; (2) take advantage of LDEF's unique capabilities; and (3) extend the investigations begun on LDEF 1. These ideas have been gleaned from investigators on LDEF 1 and others interested in the space radiation environment. They include new approaches to the investigation of Be-7 that was discovered on LDEF 1, concepts to obtain further information on the ionic charge state of cosmic rays and other energetic particles in space and other ideas to extend the investigations begun on LDEF 1.

Adams, James H., Jr.

1993-04-01

386

Measurements of the Solar Neutrino Flux From Super-Kamiokande's First 300 Days  

Microsoft Academic Search

The results of the solar neutrino flux measurements from data taken by Super-Kamiokande between the 31st of May, 1996 and the 23rd of June, 1997 are presented. Using our measurement of recoil electrons with energies above 6.5 MeV\\/c^2, we infer the flux of all ^8 B solar neutrinos to be 2.42±0.06(stat.)^+0.10_-0.07(syst.)×10^6\\/cm^2\\/s, which is 36% of the flux predicted by the

Robert Sanford; T. Hayakawa; E. Ichihara; K. Inoue; K. Ishihara; H. Ishino; Y. Itow; T. Kajita; J. Kameda; S. Kasuga; K. Kobayashi; Y. Kobayashi; Y. Koshio; K. Martens; M. Miura; M. Nakahata; S. Nakayama; A. Okada; M. Oketa; K. Okumura; M. Ota; N. Sakurai; M. Shiozawa; Y. Suzuki; Y. Takeuchi; Y. Totsuka; S. Yamada; M. Earl; A. Habig; J. T. Hong; E. Kearns; S. B. Kim; M. Masuzawa; M. D. Messier; K. Scholberg; J. L. Stone; L. R. Sulak; C. W. Walter; M. Goldhaber; T. Barszczak; W. Gajewski; P. G. Halverson; J. Hsu; W. R. Kropp; L. R. Price; F. Reines; H. W. Sobel; M. R. Vagins; K. S. Ganezer; W. E. Keig; R. W. Ellsworth; S. Tasaka; J. W. Flanagan; A. Kibayashi; J. G. Learned; S. Matsuno; V. Stenger; D. Takemori; T. Ishii; J. Kanzaki; T. Kobayashi; K. Nakamura; K. Nishikawa; Y. Oyama; A. Sakai; M. Sakuda; O. Sasaki; S. Echigo; M. Kohama; A. T. Suzuki; T. J. Haines; E. Blaufuss; R. Svoboda; M. L. Chen; Z. Conner; J. A. Goodman; G. W. Sullivan; M. Mori; J. Hill; C. K. Jung; C. Mauger; C. McGrew; E. Sharkey; B. Viren; C. Yanagisawa; W. Doki; T. Ishizuka; Y. Kitaguchi; H. Koga; K. Miyano; H. Okazawa; C. Saji; M. Takahata; A. Kusano; Y. Nagashima; M. Takita; T. Yamaguchi; M. Yoshida; M. Etoh; K. Fujita; A. Hasegawa; T. Hasegawa; S. Hatakeyama; T. Iwamoto; T. Kinebuchi; M. Koga; T. Maruyama; H. Ogawa; F. Tsushima; M. Koshiba; M. Nemoto; K. Nishijima; T. Futagami; Y. Hayato; Y. Kanaya; K. Kaneyuki; Y. Watanabe; D. Kielczewska; R. Doyle; J. George; A. Stachyra; L. Wai; J. Wilkes; K. Young

1998-01-01

387

Fluxes of energetic protons and electrons measured on board the Oersted satellite  

Microsoft Academic Search

The Charged Particle Detector (CPD) on board the Oersted satellite (649 km perigee, 865 km apogee and 96.48° inclination) currently measures energetic protons and electrons. The measured peak fluxes of E>1 MeV electrons are found to confirm the predictions of AE8-MAX, though they occur at a geographical position relatively shifted in the SAA. The fluxes of protons are one order

J. Cabrera; M. Cyamukungu; P. Stauning; A. Leonov; P. Leleux; J. Lemaire; G. Grégoire

2005-01-01

388

How Well Can We Measure the Vertical Wind Speed? Implications for Fluxes of Energy and Mass  

NASA Astrophysics Data System (ADS)

Sonic anemometers are capable of measuring the wind speed in all three dimensions at high frequencies (10-50 Hz), and are relied upon to estimate eddy-covariance-based fluxes of mass and energy over a wide variety of surfaces and ecosystems. In this study, wind-velocity measurement errors from a three-dimensional sonic anemometer with a non-orthogonal transducer orientation were estimated for over 100 combinations of angle-of-attack and wind direction using a novel technique to measure the true angle-of-attack and wind speed within the turbulent atmospheric surface layer. Corrections to the vertical wind speed varied from -5 to 37% for all angles-of-attack and wind directions examined. When applied to eddy-covariance data from three NOAA flux sites, the wind-velocity corrections increased the magnitude of CO2 fluxes, sensible heat fluxes, and latent heat fluxes by ?11%, with the actual magnitude of flux corrections dependent upon sonic anemometer, surface type, and scalar. A sonic anemometer that uses vertically aligned transducers to measure the vertical wind speed was also tested at four angles-of-attack, and corrections to the vertical wind speed measured using this anemometer were within ±1% of zero. Sensible heat fluxes over a forest canopy measured using this anemometer were 15% greater than sensible heat fluxes measured using a sonic anemometer with a non-orthogonal transducer orientation. These results indicate that sensors with a non-orthogonal transducer orientation, which includes the majority of the research-grade three-dimensional sonic anemometers currently in use, should be redesigned to minimize sine errors by measuring the vertical wind speed using one pair of vertically aligned transducers.

Kochendorfer, John; Meyers, Tilden P.; Frank, John; Massman, William J.; Heuer, Mark W.

2012-11-01

389

Solar Constant Data from Earth Radiation Budget Measurements.  

National Technical Information Service (NTIS)

At present, solar total irradiance measurements are made from four satellites using electrically self calibrating pyrheliometers, as a part of the earth radiation budget measurement programs. The Earth Radiation Budget (ERB) mission onboard Nimbus-7 space...

A. T. Mecherikunnel H. L. Kyle R. B. Lee

1990-01-01

390

Surface Radiative Fluxes from GOES-E over the Amazon Basin: Model Comparison  

NASA Astrophysics Data System (ADS)

In this study reported are results from an algorithm intercomparison initiative aimed at the development of improved estimates of surface radiative fluxes from satellite observations over the Amazon Basin. Three algorithms are used: (UMD-SRB, University of Maryland; GL1.2, INPE, Brazil; and Brasil-SR, INPE and University of Santa Catarina, Brazil). The algorithms are physically based, yet differ in their implementation and the way they address issues specific to this region, such as aerosols from biomass burning. Two fifteen day periods in 2005 were selected representing the rainy and dry seasons. The same satellite observations from GOES E were used by all the models. Ground truth from existing stations in the Amazon as well as from a new solar monitoring network of high quality have been used in evaluation. Using daily mean values for the March rainy season, it was found that: 1) the Brasil-SR and UMD-SRB estimates bear a close resemblance; 2) higher irradiances for Petrolina (semi-arid region in Northeast Brazil) are best described by the UMD-SRB and Brasil-SR, probably due to better assessment of water vapor column and absorption parameterization; 3) the GL1.2 results shows a systematic deviation, underestimating daily mean by about 20 Wm-2, but have lower dispersion than UMD-SRB or Brasil-SR; 4) irradiance interval 180 < E < 250 Wm-2 seems better described by GL1.2. This last behavior may be related to better assessment of cloudiness under partial coverage situations. September is characterized by intensive biomass burning in several Brazilian regions, particularly in the Amazon. The Northeast region is not affected by aerosols and estimates from all three models are in close agreement and have similar characteristics to those of March. For the Amazon sites: 1) lower irradiances (for overcast days) are correctly assessed; 2) UMD-SRB and Brasil-SR overestimate solar radiation, especially for higher irradiances (lower cloudiness); 3) GL1.2 model does not include aerosol effects and also overestimates the surface fluxes, but has better agreement with observations for lower irradiances. These preliminary results on surface radiative fluxes from all three models show similar accuracies when evaluated against ground observations. The advantages of each model will be synthesized to produce a version that produces best results in the Amazon Basin.

Ceballos, J. C.; Pinker, R. T.; Pereira, E. B.; Martins, F. R.; Kato, H.; de Miranda, R. M.; Wonsick, M.

2006-12-01

391

Summary of measurements of high-LET particle radiation in U.S. manned space missions.  

PubMed

A summary of measurements of high-LET particle radiation inside U.S. manned spacecraft is given for ASTP (Apollo Soyuz Test Project), Skylab and Apollo missions. The results include particle fluxes, integral LET spectra, and stopping-density charge distributions derived from measurements made in plastic nuclear track detectors worn by astronauts and located at various positions inside spacecraft. The results presented for different missions cover a wide range of shielding depth and missions type. PMID:11958206

Benton, E V; Peterson, D D; Henke, R P

1977-01-01

392

Profiles of cloud fraction and water content deduced from ground-based solar radiation measurements  

NASA Astrophysics Data System (ADS)

Ground-based measured solar radiation fluxes are used to derive simultaneously cloud water content and cloud fraction cover. In this paper we present a new method for prognostically inferring cloud microphysical properties based on previous work of Chou and Suarez. A look up table method combined with simulated annealing process is associated with the Chou and Suarez radiation transfer model called CLIRAD-SW. This model which is of great sensitivity has been validated for several atmospheres. Calculations here are conducted for an equivalent period of one year of measurement realized by the MINREST-LRE program for the Yaoundé meteorological station during the year 1984 and are focused on the previously derived average solar days similar to those proposed by Klein and more representative of the monthly solar radiation profile. In order to reduce computational time, mean values of liquid, mixed phase and ice cloud effective radius are used according to those proposed by Chou M.D. As part of our retrieving method, diffuse and global fluxes calculated for each set of cloud and aerosol microphysical characteristics are compared with the fluxes measured during the corresponding period. The obtained results are in very good agreement with those fluxes with relative errors ranging from 0.001% to 1.9% for diffuse flux and from 0.0009% to 2% for global flux. Mean cloud fraction profile obtained was generally well correlated with seasons whereas the correlation of cloud water content with seasons was not very good. However, the characteristic trend was in good agreement with the change in seasons. The overall agreement observed suggests that the method is capable of characterizing cloud water content and fraction for the given period of the day and the year although the lack of in situ measurements was a limitation for a valuable verification of the accuracy of the method.

Akana Nguimdo, L.; Njomo, D.

2010-11-01

393

High-flux x-ray undulator radiation from proposed B factory storage rings at Cornell University  

SciTech Connect

Two intersecting storage rings (8 GeV, 1 A and 3.5 GeV, 2 A) have been proposed to be built at Cornell University to enhance both the production of {ital B} mesons and synchrotron radiation. Exceedingly high x-ray flux from 3-m long undulators will be the new feature of a {ital B} factory for the CHESS laboratory. The flux produced integrated over the central cone of radiation can be as much as an order of magnitude higher than from the third-generation storage rings (now under construction) operating at 0.1 A.

Bilderback, D.H.; Batterman, B.W.; Bedzyk, M.J.; Brock, J.; Finkelstein, K.; Headrick, R.; Shen, Q. (Cornell High-Energy Synchrotron Source and the School of Applied Engineering Physics, Cornell University, Ithaca, New York 14853 (United States))

1992-01-01

394

Measurements of high-energy neutron and proton fluxes on-board "Mir-Spectr" orbital complex.  

PubMed

The measurements of high-energy neutron (with energies approximately 30-300 MeV) and proton (with energies approximately 1-200 MeV) fluxes are being conducted on-board "Mir-Spectr" orbital complex. Neutrons are detected by the undirected (FOV approximately 4 pi sr) scintillator spectrometer, consisting of 4 identical CsI(T1) detector units (the effective area for neutrons approximately 30 cm2). The gamma-quanta, which can be also detected by this instrument, are separated from neutrons by the analysis of the scintillator output pulse shape. To exclude registration of charged particles an anticoincidence plastic scintillator shield is realized in each detector unit. The proton fluxes are measured by the telescope based on 3 semiconductor detectors with small geometry factor (approximately 1 cm2 x sr). As the first result of the experiment the upper limit of the integral flux of local and albedo neutrons in the equatorial region (L<1. 1) was estimated. The results of this measurements can be useful for the radiation security. Also, the neutrons of solar flares can be detected in this experiment. PMID:11542900

Kudryavtsev, M I; Bogomolov, A V; Bogomolov, V V; Denisov YuI; Svertilov, S I

1998-01-01

395

A passive flux sampler for measuring ammonia volatilization form manure storage facilities  

SciTech Connect

An integrated horizontal flux technique was tested for quantification of ammonia (NH{sub 3}) emission from manure storage. The method is based on a simple and inexpensive passive flux sampler consisting of two disconnectable glass tubes, coated on the inside with oxalic acid. The flux sampler is mounted at a minimum of three heights, 20 to 100 cm above the storage, on each of four masts, placed perpendicular to each other around the storage. The samplers continuously integrate the horizontal flux of NH{sub 3} at the various heights. After analysis of the Nh{sub 3} content in the tubes facing the storage (exposed tubes) and surroundings (background tubes), the vertical flux of NH{sub 3} from the storage can be obtained by application of mass balance equations (micrometeorological mass balance technique). For the measurements of NH{sub 3} volatilization from slurry tanks or lagoons the technique is useful, because it is not affected by heterogenity in wind profiles and the masts with the passive flux samplers are placed on the periphery of the slurry store. The flux samplers were able to accurately quantify NH{sub 3} volatilization from slurry tanks. From above the rim of the slurry tank the horizontal net flux decline exponential with height. This may facilitate the calculation of the vertical flux of NH{sub 3}. Bypass of NH{sub 3} between exposed and background tubes may occur during periods with high wind velocities (>10 m s{sup {minus}1}) or when more than one-fifth of the oxalate in the exposed tube has reacted. However, if bypass occurs, a good estimate of NH{sub 3} volatilization can still be obtained by addition of exposed and background tubes, because the NH{sub 3} flux from storage are usually much greater than the flux from surroundings. 19 refs., 5 figs., 4 tabs.

Sommer, S.G.; Sibbesen, E.; Olesen, J.E. [Danish Inst. of Plant and Soil Science, Tjele (Germany); Nielsen, T. [Danish Agricultural Advisory Centre, Arhus (Germany); Schjorring, J.K. [Royal Veterinary and Agricultural Univ., Copenhagen (Germany)

1996-03-01

396

Methane flux, vertical gradient and mixing ratio measurements in a tropical forest  

NASA Astrophysics Data System (ADS)

Measurements of CH4 mixing ratio, vertical gradients and turbulent fluxes were carried out in a tropical forest (Reserva Biológica Cuieiras), about 60 km north of Manaus, Brazil. The methane mixing ratio and flux measurements were performed at a height of 53 m (canopy height 35 m). In addition, vertical CH4 gradients were measured within the canopy using custom made air samplers at levels of 2, 16 and 36 m above ground. The methane gradients within the canopy reveal that there is a continuous methane source at the surface. No clear evidence for aerobic methane emission from the canopy was found. The methane fluxes above the canopy are small but consistently upwards with a maximum early in the morning. The measured fluxes are in agreement with the observed CH4 gradient in the canopy. In the morning hours, a strong canopy venting peak is observed for both CH4 and CO2, but for CO2 this peak is then superimposed by photosynthetic uptake, whereas the peak lasts longer for CH4. Monthly averaged diurnal cycles of the CH4 mixing ratio show a decrease during daytime and increase during nighttime. The magnitude of the difference in CH4 mixing ratio between day and night gradually increases throughout the wet season. The fluxes required to explain the nighttime increase are in agreement with the nighttime fluxes measured above the canopy, which implies that the CH4 incre