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Sample records for albedo asymmetry parameter

  1. Aerosol Single-Scattering Albedo and Asymmetry Parameter from MFRSR Observations during the ARM Aerosol IOP 2003

    SciTech Connect

    Kassianov, Evgueni I.; Flynn, Connor J.; Ackerman, Thomas P.; Barnard, James C.

    2007-06-15

    Multi-filter Rotating Shadowband Radiometers (MFRSRs) provide routine measurements of the aerosol optical depth ( << OLE Object: Microsoft Equation 3.0 >> ) at six wavelengths (0.415, 0.5, 0.615, 0.673, 0.870 and 0.94  << OLE Object: Picture (Metafile) >> ). The single-scattering albedo ( << OLE Object: Microsoft Equation 3.0 >> ) is typically estimated from the MFRSR measurements by assuming the asymmetry parameter ( << OLE Object: Microsoft Equation 3.0 >> ). In most instances, however, it is not easy to set an appropriate value of << OLE Object: Microsoft Equation 3.0 >> due to its strong temporal and spatial variability. Here, we introduce and validate an updated version of our retrieval technique that allows one to estimate simultaneously << OLE Object: Microsoft Equation 3.0 >> and << OLE Object: Microsoft Equation 3.0 >> for different types of aerosol. We use the aerosol and radiative properties obtained during the Atmospheric Science Program (ARM) Aerosol Intensive Operational Period (IOP) to validate our retrieval in two ways. First, the MFRSR-retrieved optical properties are compared with those obtained from independent surface, Aerosol Robotic Network (AERONET) and aircraft measurements. The MFRSR-retrieved optical properties are in reasonable agreement with these independent measurements. Second, we perform radiative closure experiments using the MFRSR-retrieved optical properties. The calculated broadband values of the direct and diffuse fluxes are comparable (~ 5 << OLE Object: Microsoft Equation 3.0 >> ) to those obtained from measurements.

  2. Leading/Trailing Albedo Asymmetries of Thebe, Amalthea, and Metis

    NASA Astrophysics Data System (ADS)

    Simonelli, Damon P.; Rossier, Laura; Thomas, Peter C.; Veverka, Joseph; Burns, Joseph A.; Belton, Michael J. S.

    2000-10-01

    Using Galileo clear-filter images (effective wavelength ≈0.64 μm), we have created the first albedo maps of the small inner jovian satellites Thebe, Amalthea, and Metis. These maps clearly show that the leading sides of all three satellites are significantly brighter than their corresponding trailing sides, confirming and extending a result first reported by P. C. Thomas et al. (1998, Icarus135, 360-371). In particular, on all three moons the leading side is brighter than the trailing side by 25 to 30%. The fact that the direction and size of this albedo asymmetry is identical from satellite to satellite suggests that one common physical mechanism is governing the global albedo patterns of all three moons. The most plausible such mechanism is the impact of macroscopic meteoroids that originated outside the jovian system. These impacts, which eject the dust that forms Jupiter's ring system (M. E. Ockert-Bell et al., 1999, Icarus138, 188-213; J. A. Burns et al., 1999, Science284, 1146-1150), are probably also responsible for brightening the leading sides of these small satellites.

  3. Areal Average Albedo (AREALAVEALB)

    DOE Data Explorer

    Riihimaki, Laura; Marinovici, Cristina; Kassianov, Evgueni

    2008-01-01

    he Areal Averaged Albedo VAP yields areal averaged surface spectral albedo estimates from MFRSR measurements collected under fully overcast conditions via a simple one-line equation (Barnard et al., 2008), which links cloud optical depth, normalized cloud transmittance, asymmetry parameter, and areal averaged surface albedo under fully overcast conditions.

  4. Effects of snow physical parameters on spectral albedo and bidirectional reflectance of snow surface

    NASA Astrophysics Data System (ADS)

    Aoki, Teruo; Aoki, Tadao; Fukabori, Masashi; Hachikubo, Akihiro; Tachibana, Yoshihiro; Nishio, Fumihiko

    2000-04-01

    Observations of spectral albedo and bidirectional reflectance in the wavelength region of λ = 0.35-2.5 μm were made together with snow pit work on a flat snowfield in eastern Hokkaido, Japan. The effects of snow impurities, density, layer structure, and grain size attained by in situ and laboratory measurements were taken into account in snow models for which spectral albedos were calculated using a multiple-scattering model for the atmosphere-snow system. Comparisons of these theoretical albedos with measured ones suggest that the snow impurities were concentrated at the snow surface by dry fallout of atmospheric aerosols. The optically equivalent snow grain size was found to be of the order of a branch width of dendrites or of a dimension of narrower portion of broken crystals. This size was smaller than both the mean grain size and the effective grain size obtained from micrographs by image processing. The observational results for the bidirectional reflection distribution function (BRDF) normalized by the radiance at the nadir showed that the anisotropic reflection was very significant in the near-infrared region, especially for λ > 1.4 μm, while the visible normalized BRDF (NBRDF) patterns were relatively flat. Comparison of this result with two kinds of theoretical NBRDFs, where one having been calculated using single-scattering parameters by Mie theory and the other using the same parameters except for Henyey-Greenstein (HG) phase function obtained from the same asymmetry factor as in the Mie theory, showed that the observed NBRDF agreed with the theoretical one using the HG phase function rather than with that using the Mie phase function, while the albedos calculated with both phase functions agreed well with each other.

  5. Cassini Imaging of Iapetus and Solution of the Albedo Asymmetry Enigma

    NASA Astrophysics Data System (ADS)

    Denk, Tilmann; Spencer, John

    2014-05-01

    Cassini imaging of Iapetus during one close and several more distant flybys mainly in the first years of the mission revealed an alien and often unique landscape of this third-largest moon in the Saturnian system [1]. The data show numerous impact craters on the bright and dark terrain, equator-facing dark and pole-facing bright crater walls, huge impact basins, rather minor endogenic geologic features, a non-spherical, but ellipsoidal shape, a giant ridge which spans across half of Iapetus' circumference exactly along the equator, a newly detected global 'color dichotomy' presumably formed by dust from retrograde irregular moons, and of course the famous extreme global albedo asymmetry which has been an enigma for more than three centuries. Revealing the cause of this 'albedo dichotomy' enigma of Iapetus, where the trailing side and poles are more than 10x brighter than the leading side, was one of the major tasks for the Cassini mission. It has now been solved successfully. In the mid-1970es, deposition of exogenic dark material on the leading side, originating from outer retrograde moon Phoebe, was proposed as the cause. But this alone could not explain the global shape, sharpness, and complexity of the transition between Iapetus' bright and dark terrain. Mainly with Cassini spectrometer (CIRS) and imaging (ISS) data, all these characteristics and the asymmetry's large amplitude are now plausibly explained by runaway global thermal migration of water ice, triggered by the deposition of dark material on the leading hemisphere. This mechanism is unique to Iapetus among the Saturnian satellites for many reasons. Most important are Iapetus' slow rotation which produces unusually high daytime temperatures and water ice sublimation rates, and the size (gravity) of Iapetus which is small enough for global migration of water ice but large enough that much of the ice is retained on the surface [2]. References: [1] Denk, T., Neukum, G., Roatsch, Th., Porco, C.C., Burns, J

  6. Surface Albedo/BRDF Parameters (Terra/Aqua MODIS)

    DOE Data Explorer

    Trishchenko, Alexander

    2008-01-15

    Spatially and temporally complete surface spectral albedo/BRDF products over the ARM SGP area were generated using data from two Moderate Resolution Imaging Spectroradiometer (MODIS) sensors on Terra and Aqua satellites. A landcover-based fitting (LBF) algorithm is developed to derive the BRDF model parameters and albedo product (Luo et al., 2004a). The approach employs a landcover map and multi-day clearsky composites of directional surface reflectance. The landcover map is derived from the Landsat TM 30-meter data set (Trishchenko et al., 2004a), and the surface reflectances are from MODIS 500m-resolution 8-day composite products (MOD09/MYD09). The MOD09/MYD09 data are re-arranged into 10-day intervals for compatibility with other satellite products, such as those from the NOVA/AVHRR and SPOT/VGT sensors. The LBF method increases the success rate of the BRDF fitting process and enables more accurate monitoring of surface temporal changes during periods of rapid spring vegetation green-up and autumn leaf-fall, as well as changes due to agricultural practices and snowcover variations (Luo et al., 2004b, Trishchenko et al., 2004b). Albedo/BRDF products for MODIS on Terra and MODIS on Aqua, as well as for Terra/Aqua combined dataset, are generated at 500m spatial resolution and every 10-day since March 2000 (Terra) and July 2002 (Aqua and combined), respectively. The purpose for the latter product is to obtain a more comprehensive dataset that takes advantages of multi-sensor observations (Trishchenko et al., 2002). To fill data gaps due to cloud presence, various interpolation procedures are applied based on a multi-year observation database and referring to results from other locations with similar landcover property. Special seasonal smoothing procedure is also applied to further remove outliers and artifacts in data series.

  7. The Relationship Between Arctic Sea Ice Albedo and the Geophysical Parameters of the Ice Cover

    NASA Astrophysics Data System (ADS)

    Riihelä, A.

    2015-12-01

    The Arctic sea ice cover is thinning and retreating. Remote sensing observations have also shown that the mean albedo of the remaining ice cover is decreasing on decadal time scales, albeit with significant annual variability (Riihelä et al., 2013, Pistone et al., 2014). Attribution of the albedo decrease between its different drivers, such as decreasing ice concentration and enhanced surface melt of the ice, remains an important research question for the forecasting of future conditions of the ice cover. A necessary step towards this goal is understanding the relationships between Arctic sea ice albedo and the geophysical parameters of the ice cover. Particularly the question of the relationship between sea ice albedo and ice age is both interesting and not widely studied. The recent changes in the Arctic sea ice zone have led to a substantial decrease of its multi-year sea ice, as old ice melts and is replaced by first-year ice during the next freezing season. It is generally known that younger sea ice tends to have a lower albedo than older ice because of several reasons, such as wetter snow cover and enhanced melt ponding. However, the quantitative correlation between sea ice age and sea ice albedo has not been extensively studied to date, excepting in-situ measurement based studies which are, by necessity, focused on a limited area of the Arctic Ocean (Perovich and Polashenski, 2012).In this study, I analyze the dependencies of Arctic sea ice albedo relative to the geophysical parameters of the ice field. I use remote sensing datasets such as the CM SAF CLARA-A1 (Karlsson et al., 2013) and the NASA MeaSUREs (Anderson et al., 2014) as data sources for the analysis. The studied period is 1982-2009. The datasets are spatiotemporally collocated and analysed. The changes in sea ice albedo as a function of sea ice age are presented for the whole Arctic Ocean and for potentially interesting marginal sea cases. This allows us to see if the the albedo of the older sea

  8. Fast method of retrieving the asymmetry factor and scattering albedo from the maximum time-resolved reflectance of participating media.

    PubMed

    Qi, Hong; Ren, Ya-Tao; Chen, Qin; Ruan, Li-Ming

    2015-06-01

    This research presents a parametric study of the time-resolved hemispherical reflectance of a semi-infinite plane-parallel slab of homogeneous, nonemitting, absorbing, and anisotropic scattering medium exposed to a collimated Gaussian pulse. The one-dimensional transient radiative transfer equation was solved by using the finite volume method. The internal reflection at the medium-air interface caused by the mismatch of the refractive indices was considered. In particular, this work focused on the maximum diffuse hemispherical reflectance. Three different optical regions were identified according to the dimensionless pulsewidth βctp. The correlation between the normalized maximum hemispherical reflectance and βctp was conformed to the Boltzmann function. The coefficients in the correlating functions of the match and mismatch refractive index cases were fitted as polynomial fitting functions of the single scattering albedo ω and Henyey-Greenstein asymmetric factor g. Thus, ω and g can be simultaneously reconstructed by the semi-empirical correlations without solving the forward model. In conclusion, the proposed method can potentially retrieve the asymmetry factor and single scattering albedo of participating media accurately and efficiently.

  9. Asymmetry in the reconstructed deceleration parameter

    NASA Astrophysics Data System (ADS)

    Bernal, Carla; Cárdenas, Víctor H.; Motta, Veronica

    2017-02-01

    We study the orientation dependence of the reconstructed deceleration parameter as a function of redshift. We use the Union 2 and Loss datasets, and the well known preferred axis discussed in the literature, and find the best fit reconstructed deceleration parameter. Our results show that a low redshift transition of the reconstructed q (z) is clearly absent in one direction and amazingly sharp in the opposite one. We discuss the possibility that such behavior can be associated to large scale structures affecting the data.

  10. The beta decay asymmetry parameter of /sup 35/Ar

    SciTech Connect

    Garnett, J.D.

    1987-11-01

    The beta decay asymmetry parameter for /sup 35/Ar = /sup 35/Cl + e/sup +/ + nu/sub e/ has been remeasured in order to resolve a long standing puzzle. Previous asymmetry measurements, when combined with the comparative half-life, yield a value for the vector coupling constant, G/sub v/, that is in serious disagreement with the accepted value. We produced polarized /sup 35/Ar by a (p,n) reaction on /sup 35/Cl using the polarized proton beam provided by Lawrence Berkeley Laboratory's 88-Inch Cyclotron. The polarization of the /sup 35/Ar was determined by measuring the asymmetry of the positrons produced in /sup 35/Ar decay to the first excited state in /sup 35/Cl (branching ratio = 1.3%) in coincidence with a 1219.4 keV gamma ray. Our result, A/sub 0/ = 0.49 +- 0.10, combined with the comparative half-life yields a value for G/sub v/ in agreement with the accepted value.

  11. MISR Level 2 TOA/Cloud Albedo parameters (MIL2TCAL_V2)

    NASA Technical Reports Server (NTRS)

    Diner, David J. (Principal Investigator)

    The TOA/Cloud Albedo data contain albedo values, including finely-sampled or local (2.2 km) TOA albedos registered to the RLRA, and two coarsely-sampled (35.2 km resolution) TOA albedos projected to 30-km altitude. The local (2.2 km) albedos do not take the obscuration of cloud features into account, so they should only be treated as traditional albedos when the number of obscured pixels is low. The restrictive and expansive albedos are both available at 35.2 km resolution: the restrictive albedos are only calculated using the radiation upwelling from the pixel under consideration, whereas the expansive albedos use all the radiation emanating from the surrounding area. Therefore, the expansive albedo is closer to the traditional definition of top-of-atmosphere albedos. [Temporal_Coverage: Start_Date=2000-02-24; Stop_Date=] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Latitude_Resolution=1.1 km; Longitude_Resolution=1.1 km; Temporal_Resolution=about 15 orbits/day].

  12. Testing the hypothesis on the relationship between aerodynamic roughness length and albedo using vegetation structure parameters.

    PubMed

    Cho, Jaeil; Miyazaki, Shin; Yeh, Pat J-F; Kim, Wonsik; Kanae, Shinjiro; Oki, Taikan

    2012-03-01

    Surface albedo (α) and aerodynamic roughness length (z(0)), which partition surface net radiation into energy fluxes, are critical land surface properties for biosphere-atmosphere interactions and climate variability. Previous studies suggested that canopy structure parameters influence both α and z(0); however, no field data have been reported to quantify their relationships. Here, we hypothesize that a functional relationship between α and z(0) exists for a vegetated surface, since both land surface parameters can be conceptually related to the characteristics of canopy structure. We test this hypothesis by using the observed data collected from 50 site-years of field measurements from sites worldwide covering various vegetated surfaces. On the basis of these data, a negative linear relationship between α and log(z(0)) was found, which is related to the canopy structural parameter. We believe that our finding is a big step toward the estimation of z(0) with high accuracy. This can be used, for example, in the parameterization of land properties and the observation of z(0) using satellite remote sensing.

  13. Modeling radiative transfer in tropical rainforest canopies: sensitivity of simulated albedo to canopy architectural and optical parameters.

    PubMed

    Yanagi, Sílvia N M; Costa, Marcos H

    2011-12-01

    This study evaluates the sensitivity of the surface albedo simulated by the Integrated Biosphere Simulator (IBIS) to a set of Amazonian tropical rainforest canopy architectural and optical parameters. The parameters tested in this study are the orientation and reflectance of the leaves of upper and lower canopies in the visible (VIS) and near-infrared (NIR) spectral bands. The results are evaluated against albedo measurements taken above the K34 site at the INPA (Instituto Nacional de Pesquisas da Amazônia) Cuieiras Biological Reserve. The sensitivity analysis indicates a strong response to the upper canopy leaves orientation (χup) and to the reflectivity in the near-infrared spectral band (ρNIR,up), a smaller sensitivity to the reflectivity in the visible spectral band (ρVIS,up) and no sensitivity at all to the lower canopy parameters, which is consistent with the canopy structure. The combination of parameters that minimized the Root Mean Square Error and mean relative error are χup = 0.86, ρVIS,up = 0.062 and ρNIR,up = 0.275. The parameterizations performed resulted in successful simulations of tropical rainforest albedo by IBIS, indicating its potential to simulate the canopy radiative transfer for narrow spectral bands and permitting close comparison with remote sensing products.

  14. Genuine T, CP, CPT asymmetry parameters for the entangled B d system

    NASA Astrophysics Data System (ADS)

    Bernabéu, José; Botella, Francisco J.; Nebot, Miguel

    2016-06-01

    The precise connection between the theoretical T, CP, CPT asymmetries, in terms of transition probabilities between the filtered neutral meson B d states, and the experimental asymmetries, in terms of the double decay rate intensities for Flavour-CP eigenstate decay products in a B-factory of entangled states, is established. This allows the identification of genuine Asymmetry Parameters in the time distribution of the asymmetries and their measurability by disentangling genuine and possible fake terms. We express the nine asymmetry parameters — three different observables for each one of the three symmetries — in terms of the ingredients of the Weisskopf-Wigner dynamical description of the entangled B d -meson states and we obtain a global fit to their values from the BaBar collaboration experimental results. The possible fake terms are all compatible with zero and the information content of the nine asymmetry parameters is indeed different. The non-vanishing [InlineMediaObject not available: see fulltext.] and [InlineMediaObject not available: see fulltext.] are impressive separate direct evidence of Time-Reversal-violation and CP-violation in these transitions and compatible with Standard Model expectations. An intriguing 2 σ effect for the Re( θ) parameter responsible of CPT-violation appears which, interpreted as an upper limit, leads to |{M}_{{overline{B}}^0{overline{B}}^0}-{M}_B{{{}{^0}}_B}{^0}|<4.0× 1{0}^{-5} eV at 95% C.L. for the diagonal flavour terms of the mass matrix. It contributes to the CP-violating [InlineMediaObject not available: see fulltext.] asymmetry parameter in an unorthodox manner — in its cos(Δ M t) time dependence —, and it is accessible in facilities with non-entangled B d 's, like the LHCb experiment.

  15. Global Albedo

    Atmospheric Science Data Center

    2013-04-19

    ... the albedo. Bright surfaces have albedo near unity, and dark surfaces have albedo near zero. The DHR refers to the amount of spectral ... Atmospheric Science Data Center's  MISR Level 3 Imagery web site . The Multi-angle Imaging SpectroRadiometer observes the daylit ...

  16. Photoelectron Angular Distribution Asymmetry Parameters for Photodetachment of Li^- and Al^-.

    NASA Astrophysics Data System (ADS)

    Liu, Chien-Nan; Starace, Anthony F.

    1997-04-01

    Calculation of photoelectron angular distribution asymmetry parameters for photodetachment precesses is a more stringent test for theory than calculation of partial or total cross sections. Since asymmetry parameters involve ratios of transition matrix elements of different channels, they are particularly sensitive to the resonance behavior of transition matrix elements. We present the asymmetry parameters for photodetachment of Li^- (2s^2 ^1S) and Al^- (3s^23p^2 ^3P) using the eigenchannel R-matrix method(U.Fano and C.M. Lee, Phys. Rev. Lett. 31), 1573 (1973)^,(C.H. Greene, in Fundamental Processes of Atomic Dynamics,) edited by J.S. Briggs, H. Kleinpoppen, and H.O. Lutz (Plenum, New York, 1988), pp.105-127.. Our results are in good agreement with the available Al^- photodetachment measurements(A.M. Covington et al.), U of Nevada-Reno, private communication..

  17. Asymmetry parameters of the phase function for densely packed scattering grains

    NASA Technical Reports Server (NTRS)

    Mishchenko, Michael I.

    1994-01-01

    Spatial correlation among densely packed particles can substantially change their single-scattering properties, thus making questionable the applicability of the independent scattering approximation in calculations of light scattering by planetary regoliths. The same problem arises in geophysics in light scattering computations for snow, frosts, and bare soil. In this paper, we use a dense-medium light-scattering theory based on the introduction of the static structure factor to calculate asymmetry parameters of the phase function for densely packed particles with real refractive indices 1.31 and 1.66, approximating water ice and soil particles, respectively, and imaginary refractive indices 0, 0.01, and 0.3. For sparsely distributed, independently scattering grains, the calculated asymmetry parameters are always positive and always larger than those for densely packed particles. For densely packed grains, the asymmetry parameters may be negative but only for radius-to-wavelength ratios from about 0.1 to about 0.4. With decreasing particle size, the calculated asymmetry parameters tend to zero independently of the compaction state. In the geometrical optics regime, the asymmetry parameters for densely packed scatterers are positive and very close to those for independently scattering grains. These results may have important implications for remote sensing of the Earth and solid planetary surfaces. In particular, it is demonstrated that negative asymmetry parameters derived with some approximate multiple-scattering theories may be physically irrelevant and can be the result of using an inaccurate bidirectional reflection function combined with the ill-conditionally of the inverse scattering problem.

  18. Radiative Corrections to Asymmetry Parameter in the {Omega}{sup -{yields}{Lambda}}+K{sup -} Decay

    SciTech Connect

    Queijeiro, A.

    2010-07-29

    We compute the radiative corrections, to first order in the fine structure constant {alpha}, to the asymmetry parameter {alpha}{sub {Omega}}of the {Omega}{sup -{yields}{Lambda}}+K{sup -} decay. We use previous results where Sirlin's procedure is used to separate the radiative corrections into two parts, one independent model contribution and a model dependent one.

  19. Measurement of the asymmetry parameter for sup 29 P. beta. decay

    SciTech Connect

    Masson, G.S.; Quin, P.A. )

    1990-09-01

    The asymmetry parameter for the ground state, mirror decay of polarized {sup 29}P has been measured. The {sup 29}P were produced with the {sup 28}Si({rvec d},{ital p}) reaction, and the sample polarization was determined from a simultaneous measurement of the asymmetry for the pure Gamow-Teller transition to the first excited state in {sup 29}Si at 1.27 MeV. The result, {ital A}{sub g.s.}=0.681{plus minus}0.086, is in good agreement with the {ital V}{minus}{ital A} theory of nuclear {beta} decay.

  20. Measurement of the ground-state asymmetry parameter for the decay of sup 29 P

    SciTech Connect

    Masson, G.S.

    1988-01-01

    The ground state asymmetry parameter, A{sub gs}, was measured for the decay of polarized {sup 29}P. From A{sub gs} and the published value for ft{sub 1/2}, the decay's Fermi and Gamow-Teller strengths were deduced. Polarized {sup 29}P was produced by bombarding {sup 28}Si with 3.0 MeV vector polarized deuterons. A free standing wafer of pure natural abundance silicon crystal served as both target and host for the {sup 29}P. The target was heated to 140{degree}C and placed in a 1.0mT magnetic field to lengthen the polarization relaxation time. Positrons emitted in the decay were recorded by two detector telescopes placed at 0{degree}C and 180{degree} relative to the sample's polarization axis. A NaI detector, placed at 90{degree} was used to record gammas in coincidence with positrons, making it possible to simultaneously measure the asymmetries for both the ground state and excited state branches. The ground state asymmetry parameter, A{sub gs}, was deduced from these two asymmetries. The vector coupling constant, calculated form the measured Fermi strength, agrees with the predictions of CVC and with the accepted value for the Cabibbo angle. The measured Gamow-Teller strength agrees with recent calculations by Brown and Wildenthal, and disagree with earlier results of Azuelos and Kitching.

  1. Variation of ice crystal size, shape, and asymmetry parameter in tops of tropical deep convective clouds

    NASA Astrophysics Data System (ADS)

    van Diedenhoven, Bastiaan; Fridlind, Ann M.; Cairns, Brian; Ackerman, Andrew S.

    2014-10-01

    The variation of ice crystal properties in the tops of deep convective clouds off the north coast of Australia is analyzed. Cloud optical thickness, ice effective radius, aspect ratio of ice crystal components, crystal distortion parameter and asymmetry parameter are simultaneously retrieved from combined measurements of the Moderate Resolution Imaging Spectroradiometer (MODIS) and Polarization and Directionality of the Earth's Reflectances (POLDER) satellite instruments. The data are divided into periods with alternating weak and strong convection. Mostly plate-like particle components with aspect ratios closer to unity and lower asymmetry parameters characterize strongly convective periods, while weakly convective periods generally show lower aspect ratios, relatively more column-like shapes and somewhat greater asymmetry parameters. Results for strongly convective periods show that, with increasing cloud top temperature, the distortion parameter generally decreases, while the asymmetry parameter and effective radius increase. For one of the strongly convective periods, the rate at which effective radii increase with cloud top temperature is more than double that of the other periods, while the temperature dependence of the other microphysical quantities for this period is substantially weaker. Atmospheric state analysis indicates that these differences are concurrent with differences in middle-to-upper tropospheric zonal wind shear. The observed variation of microphysical properties may have significant effects on the shortwave radiative fluxes and cloud absorption associated with deep convection. Additionally, MODIS collection 5 effective radii are estimated to be biased small with an artificially narrow range. Collection 6 products are expected to have less severe biases that depend on cloud top temperature and atmospheric conditions.

  2. Observations of Surfzone Albedo

    NASA Astrophysics Data System (ADS)

    Sinnett, G.; Feddersen, F.

    2014-12-01

    The surfzone environment (where waves break) contains several unique and previously unconsidered processes that affect the heat budget. Entering short-wave radiation is a dominant term in both shelf and surfzone heat budgets. In contrast to the shelf, however, depth limited wave breaking in the surfzone generates spray, whitewater and suspended sediments, elevating the surface albedo (ratio of reflected to incident short-wave radiation). Elevated albedo reduces the level of solar short-wave radiation entering the water, potentially resulting in less heating. Additionally, surfzone water quality is often impacted by fecal bacteria contamination. As bacteria mortality is related to short-wave solar radiation, elevated surfzone albedo could reduce pathogen mortality, impacting human health. Albedo in the open ocean has been frequently studied and parameterizations often consider solar zenith angle, wind speed and ocean chlorophyll concentration, producing albedo values typically near 0.06. However, surfzone albedo observations have been extremely sparse, yet show depth limited wave breaking may increase the albedo by nearly a factor of 10 up to 0.5. Here, we present findings from a field study at the Scripps Institution of Oceanography pier to observe the affect of waves on surfzone albedo. Concurrent measurements were taken with a four-way radiometer (to measure both downwelling and upwelling short-wave and long wave radiation) mounted above the surfzone. A co-located GoPro camera was used to relate visual aspects of the surfzone to measured reflectance, and wave height and period were observed with a bottom mounted pressure sensor in 5 m water depth just outside the surfzone. Wind speed and direction were observed on the pier 10 m above the water surface. Here, we will examine the surfzone albedo dependence on surfzone parameters, such as wave height.

  3. Fano interference at the excitation of coherent phonons: Relation between the asymmetry parameter and the initial phase of coherent oscillations

    SciTech Connect

    Misochko, O. V. Lebedev, M. V.

    2015-04-15

    The theoretical assertion that the Fano asymmetry parameter and the asymptotic initial phase of a harmonic oscillator interacting with a continuum are interrelated is experimentally verified. By an example of coherent fully symmetric A{sub 1g} phonons in bismuth that are excited by ultrashort laser pulses at liquid helium temperature, it is demonstrated that, for negative values of the asymmetry parameter, the asymptotic phase increases as the modulus of the parameter decreases.

  4. Global Albedo

    Atmospheric Science Data Center

    2013-04-19

    ... to one in the visible region of the solar spectrum whereas deep clean ocean water has an albedo that is close to zero. Five years of ... Atmospheric Science Data Center's  MISR Level 3 Imagery  web site. The Multi-angle Imaging SpectroRadiometer observes the daylit ...

  5. Study of the decay asymmetry parameter and CP violation parameter in the Lambda(c)+ ---> Lambda pi+ decay

    SciTech Connect

    Link, J.M.; Yager, P.M.; Anjos, J.C.; Bediaga, I.; Castromonte, C.; Machado, A.A.; Magnin, J.; Massafferri, A.; de Miranda, J.M.; Pepe, I.M.; Polycarpo, E.; dos Reis, A.C.; Carrillo, S.; Casimiro, E.; Cuautle, E.; Sanchez-Hernandez, A.; Uribe, C.; Vazquez, F.; Agostino, L.; Cinquini, L.; Cumalat, J.P.; /Colorado U. /Fermilab /Frascati /Guanajuato U. /Illinois U., Urbana /Indiana U. /Korea U. /Kyungpook Natl. U. /INFN, Milan /Milan U. /North Carolina U. /Pavia U. /INFN, Pavia /Rio de Janeiro, Pont. U. Catol. /Puerto Rico U., Mayaguez /South Carolina U. /Tennessee U. /Vanderbilt U. /Wisconsin U., Madison

    2005-09-01

    Using data from the FOCUS (E831) experiment at Fermilab, we present a new measurement of the weak decay-asymmetry parameter a{sub {Lambda}{sub c}} in {Lambda}{sub c}{sup +} {yields} {Lambda}{pi}{sup +} decay. Comparing particle with antiparticle decays, we obtain the first measurement of the CP violation parameter {Alpha} {triple_bond} a{sub {Lambda}{sub c}} + a{sub {ovr {Lambda}{sub c}}}/a{sub {Lambda}{sub c}} - a{sub {ovr {Lambda}{sub c}}}. We obtain a{sub {Lambda}{sub c}} = -0.78 {+-} 0.16 {+-} 0.13 and {Alpha} = -0.07 {+-} 0.19 {+-} 0.12 where errors are statistical and systematic.

  6. Measurement of the asymmetry parameter in the {beta}-decay of {sup 35}Ar

    SciTech Connect

    Converse, A.; Haeberli, W.; Miller, M.

    1992-12-01

    The authors measured the asymmetry parameter, A{sub o}, for the beta decay of {sup 35}Ar to test the CVC hypothesis. Theory predicts A{sub o} =0.420{plus_minus}0.007 for the ground state decay of {sup 35}Ar. While early measurements disagree with this prediction (A{sub o}=0.22{plus_minus}0.03), a recent experiment gave A{sub o}= 0.49{plus_minus}0.10. The polarized sample was produced by {sup 35}Cl(p,n){sup 35}Ar, with the polarization deduced from the asymmetry in the decay to the first excited state of {sup 35}Cl. Excited state decays were identified by coincidences between {beta}`s and {gamma}`s observed in Ge detectors. The present experiment used a pure Cl{sub 2} target, higher beam current (80 nA vs. 5nA), and higher beam polarization (70% vs. 50%). Preliminary analysis of the data yields the value A{sub o} = 0.42{plus_minus}0.03. The error is dominated by the statistical uncertainty.

  7. Hemispherical power asymmetry: parameter estimation from cosmic microwave background WMAP5 data

    SciTech Connect

    Lew, Bartosz

    2008-09-15

    We re-examine the evidence for hemispherical power asymmetry, detected in the cosmic microwave background (CMB) WMAP (Wilkinson Microwave Anisotropy Probe) data using a new method. We use a data filtering, preprocessing, and a statistical approach different from those used previously, and pursue an independent method of parameter estimation. First, we analyze the hemispherical variance ratios and compare these with simulated distributions. Secondly, working within a previously proposed CMB bipolar modulation model, we constrain model parameters: the amplitude and the orientation of the modulation field, as a function of various multipole bins. Finally, we select three ranges of multipoles leading to the most anomalous signals, and we process a hundred corresponding Gaussian random field (GRF) simulations, treated as observational data, to further test the statistical significance and robustness of the hemispherical power asymmetry. For our analysis we use the Internally Linearly Coadded (ILC) full sky map, and the KQ75 cut sky V channel foreground reduced map of the WMAP five-year data (V5). We constrain the modulation parameters using a generic maximum a posteriori method. In particular, we find differences in hemispherical power distribution, which when described in terms of a model with a bipolar modulation field, exclude the field amplitude value of the isotropic model, A = 0, at the confidence level of {approx}99.5% ({approx}99.4%) in the multipole range l element of [7,19] (l element of [7,79]) for the V5 data, and at the confidence level of {approx}99.9% in the multipole range l element of [7,39] for the ILC5 data, with best-fit (modal probability distribution function) values in these particular multipole ranges of A = 0.21 (A = 0.21) and A = 0.15 respectively. However, we also point out that similar or larger significances (in terms of rejecting the isotropic model) and large best-fit modulation amplitudes are obtained in GRF simulations as well, which

  8. Opposite side jet charge tagging and measurement of CP asymmetry parameter $\\sin_{2\\beta}$ at D0

    SciTech Connect

    Zhang, Xiaojian

    2004-01-01

    This dissertation describes the first CP asymmetry parameter sin(2β) measurement by the DO collaboration, sing the opposite side jet charge tagging algorithm in determining B-flavor. The time integrated measurement yields sin(2β) = 0.82 ± 1.80, and the time dependent measurement gives sin(2β) = 1.80 ± 1.15.

  9. Dependence of nuclear quadrupole resonance transitions on the electric field gradient asymmetry parameter for nuclides with half-integer spins

    SciTech Connect

    Cho, Herman

    2016-02-28

    Allowed transition energies and eigenstate expansions have been calculated and tabulated in numerical form as functions of the electric field gradient asymmetry parameter for the zero field Hamiltonian of quadrupolar nuclides with I = 3/2,5/2,7/2, and 9/2. These results are essential to interpret nuclear quadrupole resonance (NQR) spectra and extract accurate values of the electric field gradient tensors. Furthermore, applications of NQR methods to studies of electronic structure in heavy element systems are proposed.

  10. Dependence of nuclear quadrupole resonance transitions on the electric field gradient asymmetry parameter for nuclides with half-integer spins

    NASA Astrophysics Data System (ADS)

    Cho, Herman

    2016-09-01

    Allowed transition energies and eigenstate expansions have been calculated and tabulated in numerical form as functions of the electric field gradient asymmetry parameter for the zero field Hamiltonian of quadrupolar nuclides with I = 3 / 2 , 5 / 2 , 7 / 2, and 9 / 2. These results are essential to interpret nuclear quadrupole resonance (NQR) spectra and extract accurate values of the electric field gradient tensors. Applications of NQR methods to studies of electronic structure in heavy element systems are proposed.

  11. [Dextrals and sinistrals (right-handers and left-handers): specificity of interhemispheric brain asymmetry and EEG coherence parameters].

    PubMed

    Zhavoronkova, L A

    2007-01-01

    Data of literature about morphological, functional and biochemical specificity of the brain interhemispheric asymmetry of healthy right-handers and left-handers and about peculiarity of dynamics of cerebral pathology in patients with different individual asymmetry profiles are presented at the present article. Results of our investigation by using coherence parameters of electroencephalogram (EEG) in healthy right-handers and left-handers in state of rest, during functional tests and sleeping and in patients with different forms of the brain organic damage were analyzed too. EEG coherence analysis revealed the reciprocal changing of alpha-beta and theta-delta spectral bands in right-handers whilein left-handers synchronous changing of all EEG spectral bands were observed. Data about regional-frequent specificity of EEG coherence, peculiarity of EEG asymmetry in right-handers and left-handers, aslo about specificity of EEG spectral band genesis and point of view about a role of the brain regulator systems in forming of interhemispheric asymmetry in different functional states allowed to propose the conception about principle of interhermispheric brain asymmetry formation in left-handers and left-handers. Following this conception in dextrals elements of concurrent (summary-reciprocal) cooperation are predominant at the character of interhemispheric and cortical-subcortical interaction while in sinistrals a principle of concordance (supplementary) is preferable. These peculiarities the brain organization determine, from the first side, the quicker revovery of functions damaged after cranio-cerebral trauma in left-handers in comparison right-handers and from the other side - they determine the forming of the more expressed pathology in the remote terms after exposure the low dose of radiation.

  12. [Change in parameters of interhemispheric asymmetry during simulation of a destructive action].

    PubMed

    Kozhevnikov, S P; Pronichev, I V

    2012-01-01

    Interhemispheric EEG asymmetry was studied in 26 male subjects aged 8-23 with different behavioral destructiveness levels. Subjects with higher destructiveness level in the state of rest had the focus of interhemispheric asymmetry in the temporal and frontal areas of the left hemisphere, whereas in subjects with lower destructiveness level the asymmetry focus was found in the same areas of the right hemisphere. Simulation of aggressive activity led to displacement of the asymmetry focus to the right hemisphere in both groups. However, in the group with higher destructiveness the changes in the focus were observed in the EEG theta band, which suggested the involvement of mainly stem oscillators of EEG activity in the destructive behavior. In the group with lower destructiveness changes were observed mainly in the alpha3 and beta1 bands, which indicated that cortical oscillators of EEG activity were involved in the control of the destructive behavior. The results suggest better perception and assessment of stimuli by subjects with lower aggressiveness and their choice of more adequate models of behavior.

  13. Vibrational branching ratios and asymmetry parameters in the photoionization of CO2 in the region between 650 Å and 840 Å

    National Institute of Standards and Technology Data Gateway

    SRD 119 Vibrational branching ratios and asymmetry parameters in the photoionization of CO2 in the region between 650 Å and 840 Å (Web, free access)   CO2 is studied using dispersed synchrotron radiation in the 650 Å to 850 Å spectral region. The vibrationally resolved photoelectron spectra are analyzed to generate relative vibrational transition amplitudes and the angular asymmetry parameters describing the various transitions observed.

  14. System albedo as sensed by satellites - Its definition and variability

    NASA Technical Reports Server (NTRS)

    Hughes, N. A.; Henderson-Sellers, A.

    1982-01-01

    System albedo, an important climatological and environmental parameter, is considered. Some of the problems and assumptions involved in evaluating albedo from satellite data are discussed. Clear-sky and cloud albedos over the United Kingdom and parts of northwest Europe are treated. Consideration is given to the spectral, temporal, and spatial variations and the effect of averaging. The implications of these results for those using and archiving albedo values and for future monitoring of system albedo are discussed. Normalization is of especial importance since this correction alters many albedo values. The pronounced difference in spectral albedo of the two visible channels reemphasizes the problem of attempting to calculate integrated albedo values from meteorological satellite data. The assumption of isotropic reflection is seen to be invalid, hindering the computation of accurate albedo values.

  15. Calculation of albedos for neutrons and photons

    NASA Astrophysics Data System (ADS)

    Brockhoff, Ronald Carl

    2003-07-01

    The albedo concept is used to describe radiation that appears to be reflected from a surface, although in reality this reflected radiation is comprised of radiation that has entered the medium, and is subsequently scattered back through the surface. The albedo often offers a computationally simple alternative to estimate doses from radiation reflected from surfaces surrounding a streaming region. However, albedo data available prior to this study, are limited to relatively few source energies and reflecting media, and are based on obsolete and incomplete cross sections and response functions. The Monte Carlo code MCNP is applied in this study to calculate the differential photon and neutron dose albedos, along with the differential secondary-photon dose albedo, based on modern response functions and cross section data. Differential photon dose albedo data were calculated for source energies ranging from 0.1 to 10 MeV incident on slabs of concrete, iron, lead, and water. Differential neutron dose albedo data, and the associated differential secondary-photon dose albedo data, were calculated for source energy bands ranging from 0.1 to 10 MeV, and for thermal, Californium, and 14 MeV source spectra, incident on the same four reflecting media. The results indicate that (1) the approximation of the differential photon dose albedo proposed by Chilton and Huddleston usually deviates from the raw albedo data by less than 10% for source energies between 0.1 and 10.0 MeV, (2) the new 24-parameter approximation of the differential neutron dose albedo deviates from the raw albedo data by less than 10% for source energy bands between 0.1 and 10 MeV, and (3) the five-parameter approximation of the secondary-photon dose albedo deviates from the raw albedo data by less than 25% for source energies between 0.1 and 10 MeV. The differential dose albedo approximations obtained in this study are used to solve several example radiation transport problems, where the dose from reflected

  16. Dependence of nuclear quadrupole resonance transitions on the electric field gradient asymmetry parameter for nuclides with half-integer spins

    SciTech Connect

    Cho, Herman

    2016-09-01

    Allowed transition energies and eigenstate expansions have been calculated and tabulated in numerical form as functions of the electric field gradient asymmetry parameter for the zero field Hamiltonian of quadrupolar nuclides with I = 3/2, 5/2, 7/2, and 9/2. These results may be used to interpret nuclear quadrupole resonance (NQR) spectra and extract accurate values of the electric field gradient tensors. Applications of NQR methods to studies of electronic structure in heavy element systems are proposed. This material is based upon work supported by the U.S. Department of Energy Office of Science, Office of Basic Energy Sciences, Heavy Element Chemistry program.

  17. Mie Scattering by Ensembles of Particles with Very Large Size Parameters

    NASA Astrophysics Data System (ADS)

    Wolf, S.

    2006-10-01

    MIEX is a computer program for the simulation of Mie scattering in case of arbitrarily large size parameters. The elements of the scattering matrix, efficiency factors as well as the corresponding cross sections, the albedo and the scattering asymmetry parameter are calculated. Single particles as well as particle ensembles consisting of several components and particle size distributions can be considered.

  18. Cross-section and asymmetry-parameter calculations for the outer- and inner-valence photoionization of ethane

    SciTech Connect

    Toffoli, Daniele; Simpson, Mary J.; Lucchese, Robert R.

    2004-06-01

    We have computed cross sections and asymmetry parameters for the outer- and inner-valence photoionization of ethane using the Schwinger variational method with Pade corrections. The calculated total cross section is found to be in rather good agreement with the available electron-impact and photoabsorption measurements. One-electron resonant processes in the (1e{sub g}){sup -1} (3a{sub 1g}){sup -1}, and (2a{sub 1g}){sup -1} ionization channels were examined comparing resonant states predicted from the virtual orbitals of a minimum basis set self-consistent-field (MBS-SCF) calculations with scattering resonances found using a local model potential for the electron-molecule interaction. The analysis of the interaction potential in terms of adiabatic radial components provides a description of the mechanism of the resonant trapping.

  19. Earth's Reflection: Albedo

    ERIC Educational Resources Information Center

    Gillette, Brandon; Hamilton, Cheri

    2011-01-01

    When viewing objects of different colors, you might notice that some appear brighter than others. This is because light is reflected differently from various surfaces, depending on their physical properties. The word "albedo" is used to describe how reflective a surface is. The Earth-atmosphere has a combined albedo of about 30%, a number that is…

  20. Albedos. Final report

    SciTech Connect

    Hansen, F.V.

    1993-07-01

    The albedo of the earth's surface varies dramatically from values of about 3 to 4 percent for calm bodies of water up to about 55 percent for gypsum sands. This rather broad range of reflected incoming solar radiation presents difficulties when attempting to define an average albedo for terrain over a large region from locally determined values. The patchwork, or checkerboard, appearance of the earth's surface as viewed from above is the result of various human activities, such as agriculture, the proliferation of urban sprawl, and road building. Each of these variable appearing surfaces will have individual albedos, rendering any attempt to determine an a real albedo almost an impossibility on the mesoscale. However, a vast data base exists for microscale applications for individual acreages, for example. A compilation of these data is presented.... Albedo, Solar radiation, Crops, Urban areas, Land uses.

  1. Asymmetry of short-term control of spatio-temporal gait parameters during treadmill walking

    NASA Astrophysics Data System (ADS)

    Kozlowska, Klaudia; Latka, Miroslaw; West, Bruce J.

    2017-03-01

    Optimization of energy cost determines average values of spatio-temporal gait parameters such as step duration, step length or step speed. However, during walking, humans need to adapt these parameters at every step to respond to exogenous and/or endogenic perturbations. While some neurological mechanisms that trigger these responses are known, our understanding of the fundamental principles governing step-by-step adaptation remains elusive. We determined the gait parameters of 20 healthy subjects with right-foot preference during treadmill walking at speeds of 1.1, 1.4 and 1.7 m/s. We found that when the value of the gait parameter was conspicuously greater (smaller) than the mean value, it was either followed immediately by a smaller (greater) value of the contralateral leg (interleg control), or the deviation from the mean value decreased during the next movement of ipsilateral leg (intraleg control). The selection of step duration and the selection of step length during such transient control events were performed in unique ways. We quantified the symmetry of short-term control of gait parameters and observed the significant dominance of the right leg in short-term control of all three parameters at higher speeds (1.4 and 1.7 m/s).

  2. Asymmetry of short-term control of spatio-temporal gait parameters during treadmill walking

    PubMed Central

    Kozlowska, Klaudia; Latka, Miroslaw; West, Bruce J.

    2017-01-01

    Optimization of energy cost determines average values of spatio-temporal gait parameters such as step duration, step length or step speed. However, during walking, humans need to adapt these parameters at every step to respond to exogenous and/or endogenic perturbations. While some neurological mechanisms that trigger these responses are known, our understanding of the fundamental principles governing step-by-step adaptation remains elusive. We determined the gait parameters of 20 healthy subjects with right-foot preference during treadmill walking at speeds of 1.1, 1.4 and 1.7 m/s. We found that when the value of the gait parameter was conspicuously greater (smaller) than the mean value, it was either followed immediately by a smaller (greater) value of the contralateral leg (interleg control), or the deviation from the mean value decreased during the next movement of ipsilateral leg (intraleg control). The selection of step duration and the selection of step length during such transient control events were performed in unique ways. We quantified the symmetry of short-term control of gait parameters and observed the significant dominance of the right leg in short-term control of all three parameters at higher speeds (1.4 and 1.7 m/s). PMID:28287168

  3. Factors Influencing the Mesoscale Variations in Marine Stratocumulus Albedo

    DTIC Science & Technology

    2007-01-01

    aerosols can indeed modulate cloud albedo, other parameters such as sea surface temperature may similarly affect cloud albedo. Additionally, the...major role in determining planetary albedo and tend to be located along the eastern pe- ripheries of the major oceans (Warren et al., 1988). They...cloud, in cloud and from re- motely retrieved parameters all show substantial interflight vari- ability in their spatial patterns. In some flights the

  4. Interference effects in photoelectron asymmetry parameter (β) trends of C 2s-1 states of ethyne, ethene and ethane

    NASA Astrophysics Data System (ADS)

    Decleva, Piero; Toffoli, Daniele; Kushawaha, Rajesh Kumar; MacDonald, Michael; Novella Piancastelli, Maria; Simon, Marc; Zuin, Lucia

    2016-12-01

    Photoelectron asymmetry parameters (β) of the gerade and ungerade C 2s-1 derived states of ethyne, ethene and ethane as a function of photon energy have been calculated and experimentally measured, to extend the search of interference effects on angular distributions to polyatomic molecules. The calculations cover the electron energy range from 0 to 1100 eV while the experimental measurements cover the electron energy range from 30 to 220 eV. Clear oscillations are interpreted in terms of interference of the photoelectron wave emitted from the two possible C 2s centres, or equivalently from the gerade and ungerade states associated with them. This is a microscopic analog of Young’s double-slit experiment. The effect is however quite small and requires very high experimental accuracy to be detected. It is best evidenced in the behaviour of β difference between the two channels. The connection between β trends and structural parameters shows the expected inverse correlation between oscillation period and distance between the carbon atoms, but do not simply parallel the analogous behaviour found in cross sections.

  5. Asteroid sizes and albedos

    NASA Technical Reports Server (NTRS)

    Morrison, D.

    1977-01-01

    The radiometric method of determining asteroid diameters is described, and a synthesis of radiometric and polarimetric measurements of the diameters and geometric albedos of a total of 187 asteroids is presented. An analysis is offered of the size distributions of different albedo classes down to 80-km diameter for the entire main asteroid belt (2.0-3.5 AU). The distribution of albedos is found to be strongly bimodal, with mean albedos for the C and S group of 0.035 and 0.15, respectively. The C asteroids outnumber the S asteroids at all sizes and all values of semimajor axis, with the proportion of C asteroids increasing from a little over half inside 2.5 AU to more than 95% beyond 3.0 AU. Other aspects of the distribution of C, S, and M asteroids are discussed, and the total mass of main-belt asteroids larger than 70 km is estimated.

  6. The radius and albedo of Hyperion

    NASA Technical Reports Server (NTRS)

    Cruikshank, D. P.

    1979-01-01

    A measurement of the 20-micron thermal flux from Hyperion is reported, and the radius and surface geometric albedo of this outer satellite of Saturn are computed by the photometric/radiometric method. A corrected and normalized 20-micron thermal flux of 0.033 + or - 0.012 Jy is determined. A radius of 112 + or - 15 km and a surface geometric albedo of 0.47 + or - 0.11 are obtained by assuming values of unity for the phase integral, emissivity, and bolometric/visual geometric-albedo ratio. The sensitivity of the photometric/radiometric method to the assumed values of the parameters involved is discussed, and the results are compared with similar studies of Triton. It is concluded that neither Hyperion nor Triton appears to have a geometric albedo in the lower end of the distribution of small bodies in the solar system.

  7. The albedo of Titan

    NASA Technical Reports Server (NTRS)

    Lockwood, G. W.; Lutz, B. L.; Thompson, D. T.; Bus, E. S.

    1986-01-01

    Photometric observations of Titan since 1972 show a cyclical variation of about 10 percent. A minimum value of brightness and albedo apparently occurred in 1984. Spectrophotometric observations, made annualy since 1980 at 8 A resolution, 3295-8880 A, were used to derive the value p-asterisk = 0.156 + or - 0.010 for the integrated geometric albedo in 1984. Variations of the equivalent widths of spectral features were not seen.

  8. Greenland Glacier Albedo Variability

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The program for Arctic Regional Climate Assessment (PARCA) is a NASA-funded project with the prime goal of addressing the mass balance of the Greenland ice sheet. Since the formal initiation of the program in 1995, there has been a significant improvement in the estimates of the mass balance of the ice sheet. Results from this program reveal that the high-elevation regions of the ice sheet are approximately in balance, but the margins are thinning. Laser surveys reveal significant thinning along 70 percent of the ice sheet periphery below 2000 m elevations, and in at least one outlet glacier, Kangerdlugssuaq in southeast Greenland, thinning has been as much as 10 m/yr. This study examines the albedo variability in four outlet glaciers to help separate out the relative contributions of surface melting versus ice dynamics to the recent mass balance changes. Analysis of AVHRR Polar Pathfinder albedo shows that at the Petermann and Jakobshavn glaciers, there has been a negative trend in albedo at the glacier terminus from 1981 to 2000, whereas the Stor+strommen and Kangerdlugssuaq glaciers show slightly positive trends in albedo. These findings are consistent with recent observations of melt extent from passive microwave data which show more melt on the western side of Greenland and slightly less on the eastern side. Significance of albedo trends will depend on where and when the albedo changes occur. Since the majority of surface melt occurs in the shallow sloping western margin of the ice sheet where the shortwave radiation dominates the energy balance in summer (e.g. Jakobshavn region) this region will be more sensitive to changes in albedo than in regions where this is not the case. Near the Jakobshavn glacier, even larger changes in albedo have been observed, with decreases as much as 20 percent per decade.

  9. Albedo estimates for debris

    NASA Technical Reports Server (NTRS)

    Potter, A. E.; Henize, Karl G.; Talent, D. L.

    1989-01-01

    The albedo of upper-stage breakup debris is proposed as an accurate discriminator among the various possible causes of breakup, which encompass residual fuel explosions and hypervelocity particle impacts. The fragments from an impact are covered with a thin layer of soot deposited from the destruction of polymeric circuit boards, while pressure vessel explosion fragments can be expected to remain soot-free. Albedo also facilitates the interpretation of small-debris optical telescope measurements.

  10. Bipolar high temporal resolution measurements of snow UV albedo in Sodankylä and Marambio

    NASA Astrophysics Data System (ADS)

    Meinander, Outi; Kontu, Anna; Asmi, Eija; Sanchez, Ricardo; Mei, Miguel; de Leeuw, Gerrit

    2015-04-01

    In this presentation we will give an overview of our high temporal resolution polar snow UV albedo data from Arctic Sodankylä, and from Marambio, Antarctica. These both are WMO GAW stations with many measurement parameters relevant to the albedo data usage. We will also describe our campaign based polar albedo data (SNORTEX and SOS campaigns), and an important data set of light absorbing impurities (BC) in the Arctic snow. The black carbon (BC) has been estimated to be the second most important human emission after carbon dioxide, in terms of its climate forcing in the present-day atmosphere. The reflectance effect of BC deposited on snow surface is the bigger the smaller the wavelength, i.e. the albedo effect of BC is the biggest at UV. This is also shown in SNICAR-model simulated albedo values. In Sodankylä, our bipolar snow ultraviolet (UV) albedo research started within the International Polar Year (IPY) 2007-2008. In 2007, the continuous Sodankylä snow UV albedo measurements were installed in Sodankylä, in the operational albedo field of the Finnish Meteorological Institute Arctic Research Center (FMI-ARC). These Sodankylä 1-min data during snow time were soon compared with the German Antarctic Neumayer Station UV albedo data, also with the same sensor type. In both data we found an up to 10 % decrease in albedo as a function of time within a day, ranging from 0.77 to 0.67 in Sodankylä and from 0.96 to 0.86 in Neumeyer. Physical explanations to asymmetry were found for cases with high relative humidity and low surface temperature during the previous night, favorable to frost and higher albedo on the next morning; new snow on the previous night; snow melting during day time and refreezing during night. In Marambio, in the beginning of 2013, our new continuous Finnish-Argentinian co-operation snow UV albedo measurements were installed and started as part of a larger continuous meteorological and environmental instrumentation. These new UV radiation data

  11. Excitation energies, photoionization cross sections, and asymmetry parameters of the methyl and silyl radicals

    SciTech Connect

    Velasco, A. M.; Lavín, C.; Dolgounitcheva, O.; Ortiz, J. V.

    2014-08-21

    Vertical excitation energies of the methyl and silyl radicals were inferred from ab initio electron propagator calculations on the electron affinities of CH{sub 3}{sup +} and SiH{sub 3}{sup +}. Photoionization cross sections and angular distribution of photoelectrons for the outermost orbitals of both CH{sub 3} and SiH{sub 3} radicals have been obtained with the Molecular Quantum Defect Orbital method. The individual ionization cross sections corresponding to the Rydberg channels to which the excitation of the ground state's outermost electron gives rise are reported. Despite the relevance of methyl radical in atmospheric chemistry and combustion processes, only data for the photon energy range of 10–11 eV seem to be available. Good agreement has been found with experiment for photoionization cross section of this radical. To our knowledge, predictions of the above mentioned photoionization parameters on silyl radical are made here for the first time, and we are not aware of any reported experimental measurements. An analysis of our results reveals the presence of a Cooper minimum in the photoionization of the silyl radical. The adequacy of the two theoretical procedures employed in the present work is discussed.

  12. Morphometric hemispheric asymmetry of orbitofrontal cortex in women with borderline personality disorder: a multi-parameter approach.

    PubMed

    de Araujo Filho, Gerardo Maria; Abdallah, Chadi; Sato, João Ricardo; de Araujo, Thabata Bueno; Lisondo, Cláudio Mauricio; de Faria, Álvaro Ancona; Lin, Katia; Silva, Ivaldo; Bressan, Rodrigo Affonsecca; da Silva, Julieta Freitas Ramalho; Coplan, Jeremy; Jackowski, Andrea Parolin

    2014-08-30

    Functional imaging studies have implicated the orbitofrontal cortex (OFC) in the pathophysiology of borderline personality disorder (BPD). To date, however, volume-based magnetic resonance imaging (MRI) studies have yielded mixed results. We used a surface-based processing approach that allowed us to measure five morphometric cortical features of the OFC, including volumetric (cortical thickness and surface area) and geometric (mean curvature, depth of sulcus, and metric distortion - three indicators of cortical folding) parameters. Participants comprised 25 female BPD patients with no other current psychiatric comorbidity and 25 age- and gender-matched healthy controls who received structural MRI scans. Images were processed using the Freesurfer package. All BPD patients had a history of comorbid psychiatric disorder(s) and were currently on medications. Compared with controls, the BPD group showed reduced cortical thickness, surface area, mean curvature, depth of sulcus, and metric distortion in the right medial OFC. In the left medial OFC, the BPD group had reduced cortical thickness and mean curvature, but increased metric distortion. This study confirmed the utility of surface-based analysis in the study of BPD cortical structures. In addition, we observed extensive structural abnormalities in the medial OFC of female subjects with BPD, findings that were most pronounced in the right OFC, with preliminary data suggesting hemispheric asymmetry.

  13. The albedo of Earth

    NASA Astrophysics Data System (ADS)

    Stephens, Graeme L.; O'Brien, Denis; Webster, Peter J.; Pilewski, Peter; Kato, Seiji; Li, Jui-lin

    2015-03-01

    The fraction of the incoming solar energy scattered by Earth back to space is referred to as the planetary albedo. This reflected energy is a fundamental component of the Earth's energy balance, and the processes that govern its magnitude, distribution, and variability shape Earth's climate and climate change. We review our understanding of Earth's albedo as it has progressed to the current time and provide a global perspective of our understanding of the processes that define it. Joint analyses of surface solar flux data that are a complicated mix of measurements and model calculations with top-of-atmosphere (TOA) flux measurements from current orbiting satellites yield a number of surprising results including (i) the Northern and Southern Hemispheres (NH, SH) reflect the same amount of sunlight within ~ 0.2 W m-2. This symmetry is achieved by increased reflection from SH clouds offsetting precisely the greater reflection from the NH land masses. (ii) The albedo of Earth appears to be highly buffered on hemispheric and global scales as highlighted by both the hemispheric symmetry and a remarkably small interannual variability of reflected solar flux (~0.2% of the annual mean flux). We show how clouds provide the necessary degrees of freedom to modulate the Earth's albedo setting the hemispheric symmetry. We also show that current climate models lack this same degree of hemispheric symmetry and regulation by clouds. The relevance of this hemispheric symmetry to the heat transport across the equator is discussed.

  14. The solar zenith angle dependence of desert albedo

    NASA Astrophysics Data System (ADS)

    Wang, Zhuo; Barlage, Michael; Zeng, Xubin; Dickinson, Robert E.; Schaaf, Crystal B.

    2005-03-01

    Most land models assume that the bare soil albedo is a function of soil color and moisture but independent of solar zenith angle (SZA). However, analyses of the Moderate Resolution Imaging Spectroradiometer (MODIS) Bidirectional Reflectance Distribution Function (BRDF) and albedo data over thirty desert locations indicate that bare soil albedo does vary with SZA. This is further confirmed using the in situ data. In particular, bare soil albedo normalized by its value at 60° SZA can be adequately represented by a one-parameter formulation (1 + C)/(1 + 2C * cos(SZA)) or a two-parameter formulation (1 + B1 * f1(SZA) + B2 * f2(SZA)). Using the MODIS and in situ data, the empirical parameters C, B1, and B2 are taken as 0.15, 0.346 and 0.063. The SZA dependence of soil albedo is also found to significantly affect the modeling of land surface energy balance over a desert site.

  15. Generating multi-scale albedo look-up maps using MODIS BRDF/Albedo products and landsat imagery

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Surface albedo determines radiative forcing and is a key parameter for driving Earth’s climate. Better characterization of surface albedo for individual land cover types can reduce the uncertainty in estimating changes to Earth’s radiation balance due to land cover change. This paper presents a mult...

  16. The albedo of snow for partially cloudy skies

    NASA Technical Reports Server (NTRS)

    Choudhury, B. J.; Chang, A. T. C.

    1980-01-01

    The input parameters of the model are atmospheric precipitable water, ozone content, turbidity, cloud optical thickness, size and shape of ice crystal of snow and surface pressure. The model outputs spectral and integrated solar flux snow reflectance as a function of solar elevation and fractional cloudcover. The model is illustrated using representative parameters for the Antarctic coastal regions. The albedo for a clear sky depends inversely on the solar elevation. At high elevation the albedo depends primarily upon the grain size; at low elevation this dependence is on grain size and shape. The gradient of the albedo-elevation curve increases as the grains get larger and faceted. The albedo for a dense overcast is a few percent higher than the clear sky albedo at high elevations. A simple relation between the grain size and the overcast albedo is obtained. For a set of grain size and shape, the albedo matrices (the albedo as a function of solar elevation and fractional cloudcover) are tabulated.

  17. Diurnal and seasonal variations of surface albedo in a spring wheat field of arid lands of Northwestern China.

    PubMed

    Zhang, Ya-feng; Wang, Xin-ping; Pan, Yan-xia; Hu, Rui

    2013-01-01

    Surface albedo greatly affects the radiation energy balance of croplands and is a significant factor in crop growth monitoring and yield estimation. Precise determination of surface albedo is thus important. This study aimed to examine the influence of growth stages (tillering, jointing, heading, filling and maturity) on albedo and its diurnal asymmetry by measuring diurnal albedo variations. Results indicated that the daily mean surface albedo generally exhibited an increased tendency during tillering to heading but decreased after heading. Surface albedos were much higher in the morning than the corresponding values of the same solar elevation angles in the afternoon when the solar elevation angle was less than 40°, indicating a diurnal asymmetry in surface albedo. However, less difference was found in surface albedos between forenoon and afternoon when the solar elevation angle was greater than 40°. Dew droplets on the leaf surface in the morning were assumed to be the main factor resulting in the diurnal asymmetry in albedo of spring wheat.

  18. Retrieval of Areal-averaged Spectral Surface Albedo from Transmission Data Alone: Computationally Simple and Fast Approach

    SciTech Connect

    Kassianov, Evgueni I.; Barnard, James C.; Flynn, Connor J.; Riihimaki, Laura D.; Michalsky, Joseph; Hodges, G. B.

    2014-10-25

    We introduce and evaluate a simple retrieval of areal-averaged surface albedo using ground-based measurements of atmospheric transmission alone at five wavelengths (415, 500, 615, 673 and 870nm), under fully overcast conditions. Our retrieval is based on a one-line semi-analytical equation and widely accepted assumptions regarding the weak spectral dependence of cloud optical properties, such as cloud optical depth and asymmetry parameter, in the visible and near-infrared spectral range. To illustrate the performance of our retrieval, we use as input measurements of spectral atmospheric transmission from Multi-Filter Rotating Shadowband Radiometer (MFRSR). These MFRSR data are collected at two well-established continental sites in the United States supported by the U.S. Department of Energy’s (DOE’s) Atmospheric Radiation Measurement (ARM) Program and National Oceanic and Atmospheric Administration (NOAA). The areal-averaged albedos obtained from the MFRSR are compared with collocated and coincident Moderate Resolution Imaging Spectroradiometer (MODIS) white-sky albedo. In particular, these comparisons are made at four MFRSR wavelengths (500, 615, 673 and 870nm) and for four seasons (winter, spring, summer and fall) at the ARM site using multi-year (2008-2013) MFRSR and MODIS data. Good agreement, on average, for these wavelengths results in small values (≤0.01) of the corresponding root mean square errors (RMSEs) for these two sites. The obtained RMSEs are comparable with those obtained previously for the shortwave albedos (MODIS-derived versus tower-measured) for these sites during growing seasons. We also demonstrate good agreement between tower-based daily-averaged surface albedos measured for “nearby” overcast and non-overcast days. Thus, our retrieval originally developed for overcast conditions likely can be extended for non-overcast days by interpolating between overcast retrievals.

  19. Surface albedo of cometary nucleus

    NASA Astrophysics Data System (ADS)

    Mukai, T.; Mukai, S.

    A variation of the albedo on the illuminated disk of a comet nucleus is estimated, taking into account the multiple reflection of incident light due to small scale roughness. The dependences of the average albedo over the illuminated disk on the degree of roughness and on the complex refractive index of the surface materials are examined. The variation estimates are compared with measurements of the nucleus albedo of Comet Halley (Reitsema et al., 1987).

  20. Soil Albedo in Relation to Soil Color, Moisture and Roughness

    NASA Astrophysics Data System (ADS)

    Fontes, Adan Fimbres

    Land surface albedo is the ratio of reflected to incident solar radiation. It is a function of several surface parameters including soil color, moisture, roughness and vegetation cover. A better understanding of albedo and how it changes in relation to variations in these parameters is important in order to help improve our ability to model the effects of land surface modifications on climate. The objectives of this study were (1) To determine empirical relationships between smooth bare soil albedo and soil color, (2) To develop statistical relationships between albedo and ground-based thematic mapper (TM) measurements of spectral reflectances, (3) To determine how increased surface roughness caused by tillage reduces bare soil albedo and (4) To empirically relate albedo with TM data and other physical characteristics of mixed grass/shrubland sites at Walnut Gulch Watershed. Albedos, colors and spectral reflectances were measured by Eppley pyranometer, Chroma Meter CR-200 and a Spectron SE-590, respectively. Measurements were made on two field soils (Gila and Pima) at the Campus Agricultural Center (CAC), Tucson, AZ. Soil surface roughness was measured by a profile meter developed by the USDA/ARS. Additional measurements were made at the Maricopa Agricultural Center (MAC) for statistical model testing. Albedos of the 15 smooth, bare soils (plus silica sand) were determined by linear regression to be highly correlated (r^2 = 0.93, p > 0.01) with color values for both wet and dry soil conditions. Albedos of the same smooth bare soils were also highly correlated (r^2>=q 0.86, p > 0.01) with spectral reflectances. Testing of the linear regression equations relating albedo to soil color and spectral reflectances using the data from MAC showed a high correlation. A general nonlinear relationship given by y = 8.366ln(x) + 37.802 r^2 = 0.71 was determined between percent reduction in albedo (y) and surface roughness index (x) for wet and dry Pima and Gila field soils

  1. The albedo of fractal stratocumulus clouds

    NASA Technical Reports Server (NTRS)

    Cahalan, Robert F.; Ridgway, William; Wiscombe, Warren J.; Bell, Thomas L.; Snider, Jack B.

    1994-01-01

    An increase in the planetary albedo of the earth-atmosphere system by only 10% can decrease the equilibrium surface temperature to that of the last ice age. Nevertheless, albedo biases of 10% or greater would be introduced into large regions of current climate models if clouds were given their observed liquid water amounts, because of the treatment of clouds as plane parallel. The focus on marine stratocumulus clouds is due to their important role in cloud radiative forcing and also that, of the wide variety of earth's cloud types, they are most nearly plane parallel, so that they have the least albedo bias. The fractal model employed here reproduces both the probability distribution and the wavenumber spectrum of the stratocumulus liquid water path, as observed during the First ISCCP Regional Experiment (FIRE). A single new fractal parameter 0 less than or equal to f less than or equal to 1, is introduced and determined empirically by the variance of the logarithm of the vertically integrated liquid water. The reduced reflectivity of fractal stratocumulus clouds is approximately given by the plane-parallel reflectivity evaluated at a reduced 'effective optical thickness,' which when f = 0.5 is tau(sub eff) approximately equal to 10. Study of the diurnal cycle of stratocumulus liquid water during FIRE leads to a key unexpected result: the plane-parallel albedo bias is largest when the cloud fraction reaches 100%, that is, when any bias associated with the cloud fraction vanishes. This is primarily due to the variability increase with cloud fraction. Thus, the within-cloud fractal structure of stratocumulus has a more significant impact on estimates of its mesoscale-average albedo than does the cloud fraction.

  2. NEOWISE Diameters and Albedos V1.0

    NASA Astrophysics Data System (ADS)

    Mainzer, A. K.; Bauer, J. M.; Cutri, R. M.; Grav, T.; Kramer, E. A.; Masiero, J. R.; Nugent, C. R.; Sonnett, S. M.; Stevenson, R. A.; Wright, E. L.

    2016-06-01

    This PDS data set represents a compilation of published diameters, optical albedos, near-infrared albedos, and beaming parameters for minor planets detected by NEOWISE during the fully cryogenic, 3-band cryo, post-cryo and NEOWISE-Reactivation Year 1 operations. It contains data covering near-Earth asteroids, Main Belt asteroids, active Main Belt objects, Hildas, Jupiter Trojans, Centaurs, and Jovian and Saturnian irregular satellites. Methodology for physical property determination is described in the referenced articles.

  3. Joint albedo estimation and pose tracking from video.

    PubMed

    Taheri, Sima; Sankaranarayanan, Aswin C; Chellappa, Rama

    2013-07-01

    The albedo of a Lambertian object is a surface property that contributes to an object's appearance under changing illumination. As a signature independent of illumination, the albedo is useful for object recognition. Single image-based albedo estimation algorithms suffer due to shadows and non-Lambertian effects of the image. In this paper, we propose a sequential algorithm to estimate the albedo from a sequence of images of a known 3D object in varying poses and illumination conditions. We first show that by knowing/estimating the pose of the object at each frame of a sequence, the object's albedo can be efficiently estimated using a Kalman filter. We then extend this for the case of unknown pose by simultaneously tracking the pose as well as updating the albedo through a Rao-Blackwellized particle filter (RBPF). More specifically, the albedo is marginalized from the posterior distribution and estimated analytically using the Kalman filter, while the pose parameters are estimated using importance sampling and by minimizing the projection error of the face onto its spherical harmonic subspace, which results in an illumination-insensitive pose tracking algorithm. Illustrations and experiments are provided to validate the effectiveness of the approach using various synthetic and real sequences followed by applications to unconstrained, video-based face recognition.

  4. The Ultraviolet Albedo of Ganymede

    NASA Technical Reports Server (NTRS)

    McGrath, Melissa; Hendrix, Amanda

    2013-01-01

    A large set of ultraviolet images of Ganymede have been acquired with the Hubble Space Telescope over the last 15 years. These images have been used almost exclusively to study Ganymede's stunning auroral emissions (Feldman et al. 2000; Eviatar et al. 2001; McGrath et al. 2004; Saur et al. 2011; McGrath et al. 2013), and even the most basic information about Ganymede's UV albedo has yet to be gleaned from these data. We will present a first-cut analysis of both disk-averaged and spatially-resolved UV albedos of Ganymede, with focus on the spatially-resolved Lyman-alpha albedo, which has never been considered previously for this satellite. Ganymede's visibly bright regions are known to be rich in water ice, while the visibly dark regions seem to be more carbonaceous (Carlson et al., 1996). At Lyman-alpha, these two species should also have very different albedo values.

  5. Snowmelt Increase Through Albedo Reduction

    DTIC Science & Technology

    1988-12-01

    Studies of Snow and Ice in Hyvarinen, T. and J. Lammasnieme (1987) Mountain Regions, International Association of Infrared measurement of free-water...snow-climate feedback, and the reduction in albedo by darkening agents has been studied and practiced extensively. Although much is known about albedo...sometimes CHARACTERISTICS gets in the way of man’s activities and must be removed as quickly as possible. When snow is Many studies of crystal growth in snow

  6. Albedo of coastal landfast sea ice in Prydz Bay, Antarctica: Observations and parameterization

    NASA Astrophysics Data System (ADS)

    Yang, Qinghua; Liu, Jiping; Leppäranta, Matti; Sun, Qizhen; Li, Rongbin; Zhang, Lin; Jung, Thomas; Lei, Ruibo; Zhang, Zhanhai; Li, Ming; Zhao, Jiechen; Cheng, Jingjing

    2016-05-01

    The snow/sea-ice albedo was measured over coastal landfast sea ice in Prydz Bay, East Antarctica (off Zhongshan Station) during the austral spring and summer of 2010 and 2011. The variation of the observed albedo was a combination of a gradual seasonal transition from spring to summer and abrupt changes resulting from synoptic events, including snowfall, blowing snow, and overcast skies. The measured albedo ranged from 0.94 over thick fresh snow to 0.36 over melting sea ice. It was found that snow thickness was the most important factor influencing the albedo variation, while synoptic events and overcast skies could increase the albedo by about 0.18 and 0.06, respectively. The in-situ measured albedo and related physical parameters (e.g., snow thickness, ice thickness, surface temperature, and air temperature) were then used to evaluate four different snow/ice albedo parameterizations used in a variety of climate models. The parameterized albedos showed substantial discrepancies compared to the observed albedo, particularly during the summer melt period, even though more complex parameterizations yielded more realistic variations than simple ones. A modified parameterization was developed, which further considered synoptic events, cloud cover, and the local landfast sea-ice surface characteristics. The resulting parameterized albedo showed very good agreement with the observed albedo.

  7. Characteristics of meat emulsion systems as influenced by different levels of lemon albedo.

    PubMed

    Sarıçoban, C; Ozalp, B; Yılmaz, M T; Ozen, G; Karakaya, M; Akbulut, M

    2008-11-01

    The effect of the addition of lemon albedo on the functional properties of emulsions was studied by using a model system. Oil/water (O/W) model emulsion systems were prepared by the addition of two types of lemon albedo (raw and dehydrated) at five concentrations (0.0%, 2.5%, 5.0%, 7.5% and 10%) to mechanically deboned chicken meat. The emulsion capacity, stability, viscosity and flow properties of the prepared model emulsions were analyzed. In addition, the colour parameters of cooked emulsion gel were determined. The addition of lemon albedo increased the emulsion capacity (EC) and the highest EC value was reached with 5% of albedo added. However, further increase in the albedo concentration caused an inverse trend in the EC values. A similar trend was observed in the emulsion stability (ES) values. Dehydrated albedo (DA) addition caused higher EC and ES values than did raw albedo (RA). DA increased the L(∗), a(∗) and b(∗) values of the cooked emulsion gels. Emulsion viscosity (EV) values were positively correlated with an increase in albedo concentration and the highest EV value was obtained from the emulsions with 10% albedo. Albedo addition did not change the flow properties of the emulsions and, in addition, increased the pseudoplasticity. As a consequence, the use of lemon albedo might be a potential dietary fiber source to enhance the functional and technological properties for frankfurter-type meat products.

  8. Evaluating biases in simulated land surface albedo from CMIP5 global climate models

    NASA Astrophysics Data System (ADS)

    Li, Yue; Wang, Tao; Zeng, Zhenzhong; Peng, Shushi; Lian, Xu; Piao, Shilong

    2016-06-01

    Land surface albedo is a key parameter affecting energy balance and near-surface climate. In this study, we used satellite data to evaluate simulated surface albedo in 37 models participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5). There was a systematic overestimation in the simulated seasonal cycle of albedo with the highest bias occurring during the Northern Hemisphere's winter months. The bias in surface albedo during the snow-covered season was classified into that in snow cover fraction (SCF) and albedo contrast (β1). There was a general overestimation of β1 due to the simulated snow-covered albedo being brighter than the observed value; negative biases in SCF were not always related to negative albedo biases, highlighting the need for realistic representation of snow-covered albedo in models. In addition, models with a lower leaf area index (LAI) tend to produce a higher surface albedo over the boreal forests during the winter, which emphasizes the necessity of improving LAI simulations in CMIP5 models. Insolation weighting showed that spring albedo biases were of greater importance for climate. The removal of albedo biases is expected to improve temperature simulations particularly over high-elevation regions.

  9. MISR Level 3 Albedo and Cloud Versioning

    Atmospheric Science Data Center

    2016-11-04

      MISR Level 3 Albedo and Cloud Versioning Component Global Albedo Product (CGAL) and Component Global Cloud Product (CGCL) - Daily, ...  CLOUD - Wind Vectors, Height Histogram Stage 1:  ALBEDO - Expansive, Restrictive and Local Albedo (except over snow and ice) ...

  10. Retrieval of the single scattering albedo in the El Paso-Juarez Airshed using the TUV model and a UV-MFRSR radiometer

    NASA Astrophysics Data System (ADS)

    Medina, Richard; Fitzgerald, Rosa M.; Min, Qilong

    2012-01-01

    A methodology to retrieve Single Scattering Albedo (SSA) values employing the ratio of Direct to Diffuse Irradiances (DDR) is used and applied to the El Paso-Juarez Airshed, a challenging region where air masses interact. The TUV model was used to obtain the calculated DDR irradiances, and the experimental irradiances were obtained from a UV-MFRSR instrument located in the city of El Paso, Texas. The wavelengths used were 332 nm and 368 nm. The retrieved SSA values at both 332 nm and 368 nm were higher in a lightly polluted day (0.66-0.81 at 332 nm, and 0.61 to 0.80 at 368 nm) than in a heavier polluted day (0.56-0.70 at 332 nm and 0.53-0.66 at 368 nm). A sensitivity study of the ground albedo and the asymmetry parameter was performed, which indicated that the variation of the asymmetry parameter is a secondary effect in the retrievals of SSA. In addition, the variation of SSA values during the day was also analyzed for the El Paso-Juarez Airshed and linked to the flow of air masses into the region using HYSPLIT trajectories. A presence of absorptive aerosols was observed during the late morning and the middle of the day. This methodology can be applied in any area, and is particularly useful for cities that experience episodes of high PM concentrations.

  11. Albedo and transmittance of inhomogeneous stratus clouds

    SciTech Connect

    Zuev, V.E.; Kasyanov, E.I.; Titov, G.A.

    1996-04-01

    A highly important topic is the study of the relationship between the statistical parameters of optical and radiative charactertistics of inhomogeneous stratus clouds. This is important because the radiation codes of general circulation models need improvement, and it is important for geophysical information. A cascade model has been developed at the Goddard Space Flight Center to treat stratocumulus clouds with the simplest geometry and horizontal fluctuations of the liquid water path (optical thickness). The model evaluates the strength with which the stochastic geometry of clouds influences the statistical characteristics of albedo and the trnasmittance of solar radiation.

  12. Albedo estimates for land surface models and support for a new paradigm based on foliage nitrogen concentration

    SciTech Connect

    Hollinger, D.; Ollinger, S. V.; Richardson, A. D.; Martin, M. E.; Meyers, T. P.; Dail, D. B.; Scott, N. A.; Arkebauer, T. J.; Baldocchi, D. D.; Clark, K. L.; Curtis, Peter; Davis, K. J.; Desai, Desai Ankur R.; Dragoni, Danilo; Goulden, M. L.; Gu, Lianhong; Katul, G. G.; Pallardy, Stephen G.; Pawu, K. T.; Schmid, H. P.; Stoy, P. C.; Suyker, A. E.; Verma, Shashi

    2009-02-01

    Vegetation albedo is a critical component of the Earth s climate system, yet efforts to evaluate and improve albedo parameterizations in climate models have lagged relative to other aspects of model development. Here, we calculated growing season albedos for deciduous and evergreen forests, crops, and grasslands based on over 40 site-years of data from the AmeriFlux network and compared them with estimates presently used in the land surface formulations of a variety of climate models. Generally, the albedo estimates used in land surface models agreed well with this data compilation. However, a variety of models using fixed seasonal estimates of albedo overestimated the growing season albedo of northerly evergreen trees. In contrast, climatemodels that rely on a common two-stream albedo submodel provided accurate predictions of boreal needle-leaf evergreen albedo but overestimated grassland albedos. Inverse analysis showed that parameters of the two-stream model were highly correlated. Consistent with recent observations based on remotely sensed albedo, the AmeriFlux dataset demonstrated a tight linear relationship between canopy albedo and foliage nitrogen concentration (for forest vegetation: albedo 50.0110.071%N, r250.91; forests, grassland, and maize: albedo50.0210.067%N, r250.80). However, this relationship saturated at the higher nitrogen concentrations displayed by soybean foliage. We developed similar relationships between a foliar parameter used in the two-stream albedo model and foliage nitrogen concentration. These nitrogen-based relationships can serve as the basis for a new approach to land surface albedo modeling that simplifies albedo estimation while providing a link to other important ecosystem processes.

  13. Earth's albedo variations 1998-2014 as measured from ground-based earthshine observations

    NASA Astrophysics Data System (ADS)

    Palle, E.; Goode, P. R.; Montañés-Rodríguez, P.; Shumko, A.; Gonzalez-Merino, B.; Lombilla, C. Martinez; Jimenez-Ibarra, F.; Shumko, S.; Sanroma, E.; Hulist, A.; Miles-Paez, P.; Murgas, F.; Nowak, G.; Koonin, S. E.

    2016-05-01

    The Earth's albedo is a fundamental climate parameter for understanding the radiation budget of the atmosphere. It has been traditionally measured not only from space platforms but also from the ground for 16 years from Big Bear Solar Observatory by observing the Moon. The photometric ratio of the dark (earthshine) to the bright (moonshine) sides of the Moon is used to determine nightly anomalies in the terrestrial albedo, with the aim of quantifying sustained monthly, annual, and/or decadal changes. We find two modest decadal scale cycles in the albedo, but with no significant net change over the 16 years of accumulated data. Within the evolution of the two cycles, we find periods of sustained annual increases, followed by comparable sustained decreases in albedo. The evolution of the earthshine albedo is in remarkable agreement with that from the Clouds and the Earth's Radiant Energy System instruments, although each method measures different slices of the Earth's Bond albedo.

  14. A REVISED ASTEROID POLARIZATION-ALBEDO RELATIONSHIP USING WISE/NEOWISE DATA

    SciTech Connect

    Masiero, Joseph R.; Mainzer, A. K.; Bauer, J. M.; Wright, E. L.; McMillan, R. S.; Tholen, D. J.; Blain, A. W.

    2012-04-20

    We present a reanalysis of the relationship between asteroid albedo and polarization properties using the albedos derived from the Wide-field Infrared Survey Explorer. We find that the function that best describes this relation is a three-dimensional linear fit in the space of log (albedo)-log (polarization slope)-log (minimum polarization). When projected to two dimensions, the parameters of the fit are consistent with those found in previous work. We also define p* as the quantity of maximal polarization variation when compared with the albedo and present the best-fitting albedo-p* relation. Some asteroid taxonomic types stand out in this three-dimensional space, notably the E, B, and M Tholen types, while others cluster in clumps coincident with the S- and C-complex bodies. We note that both low albedo and small (D < 30 km) asteroids are underrepresented in the polarimetric sample, and we encourage future polarimetric surveys to focus on these bodies.

  15. Asteroid magnitudes, UBV colors, and IRAS albedos and diameters

    NASA Technical Reports Server (NTRS)

    Tedesco, Edward F.

    1989-01-01

    This paper lists absolute magnitudes and slope parameters for known asteroids numbered through 3318. The values presented are those used in reducing asteroid IR flux data obtained with the IRAS. U-B colors are given for 938 asteroids, and B-V colors are given for 945 asteroids. The IRAS albedos and diameters are tabulated for 1790 asteroids.

  16. Seasonal variation of vertical distribution of aerosol single scattering albedo over Indian sub-continent: RAWEX aircraft observations

    NASA Astrophysics Data System (ADS)

    Suresh Babu, S.; Nair, Vijayakumar S.; Gogoi, Mukunda M.; Krishna Moorthy, K.

    2016-01-01

    To characterize the vertical distribution of aerosols and its seasonality (especially the single scattering albedo, SSA) extensive profiling of aerosol scattering and absorption coefficients have been carried out using an instrumented aircraft from seven base stations spread across the Indian mainland during winter 2012 and spring/pre-monsoon 2013 under the Regional Aerosol Warming Experiment (RAWEX). Spatial variation of the vertical profiles of the asymmetry parameter, the wavelength exponent of the absorption coefficient and the single scattering albedo, derived from the measurements, are used to infer the source characteristics of winter and pre-monsoon aerosols as well as the seasonality of free tropospheric aerosols. The relatively high value of the wavelength exponent of absorption coefficient over most of the regions indicates the contribution from biomass burning and dust aerosols up to lower free tropospheric altitudes. A clear enhancement in aerosol loading and its absorbing nature is seen at lower free troposphere levels (above the planetary boundary layer) over the entire mainland during spring/pre-monsoon season compared to winter, whereas concentration of aerosols within the boundary layer showed a decrease from winter to spring. This could have significant implications on the aerosol heating structure over the Indian region and hence the regional climate.

  17. Direct determination of surface albedos from satellite imagery

    NASA Technical Reports Server (NTRS)

    Mekler, Y.; Joseph, J. H.

    1983-01-01

    An empirical method to measure the spectral surface albedo of surfaces from Landsat imagery is presented and analyzed. The empiricism in the method is due only to the fact that three parameters of the solution must be determined for each spectral photograph of an image on the basis of independently known albedos at three points. The approach is otherwise based on exact solutions of the radiative transfer equation for upwelling intensity. Application of the method allows the routine construction of spectral albedo maps from satelite imagery, without requiring detailed knowledge of the atmospheric aerosol content, as long as the optical depth is less than 0.75, and of the calibration of the satellite sensor.

  18. Albedo dichotomy of Rhea - Hapke analysis of Voyager photometry

    NASA Technical Reports Server (NTRS)

    Verbiscer, Anne J.; Veverka, Joseph

    1989-01-01

    The Hapke (1986) model has been well fitted to both full-disk and disk-resolved Voyager observations. The low phase angle data indicate a substantial opposition effect, and the Hapke analysis results show that while the regolith compaction parameter for Rhea is definitely larger than for Titania, it is comparable to that of the moon. Photometric differences other than albedo are noted between the leading and trailing hemispheres of the satellite. The albedo map of Rhea presented reproduces the observed lightcurve and demonstrates that no terrain or feature in the trailing hemisphere is as bright as any in the leading hemisphere. A quasi-circular low albedo region near the antiapex of motion is discovered.

  19. Can increasing albedo of existing ship wakes reduce climate change?

    NASA Astrophysics Data System (ADS)

    Crook, Julia A.; Jackson, Lawrence S.; Forster, Piers M.

    2016-02-01

    Solar radiation management schemes could potentially alleviate the impacts of global warming. One such scheme could be to brighten the surface of the ocean by increasing the albedo and areal extent of bubbles in the wakes of existing shipping. Here we show that ship wake bubble lifetimes would need to be extended from minutes to days, requiring the addition of surfactant, for ship wake area to be increased enough to have a significant forcing. We use a global climate model to simulate brightening the wakes of existing shipping by increasing wake albedo by 0.2 and increasing wake lifetime by ×1440. This yields a global mean radiative forcing of -0.9 ± 0.6 Wm-2 (-1.8 ± 0.9 Wm-2 in the Northern Hemisphere) and a 0.5°C reduction of global mean surface temperature with greater cooling over land and in the Northern Hemisphere, partially offsetting greenhouse gas warming. Tropical precipitation shifts southward but remains within current variability. The hemispheric forcing asymmetry of this scheme is due to the asymmetry in the distribution of existing shipping. If wake lifetime could reach ~3 months, the global mean radiative forcing could potentially reach -3 Wm-2. Increasing wake area through increasing bubble lifetime could result in a greater temperature reduction, but regional precipitation would likely deviate further from current climatology as suggested by results from our uniform ocean albedo simulation. Alternatively, additional ships specifically for the purpose of geoengineering could be used to produce a larger and more hemispherically symmetrical forcing.

  20. Albedo over rough snow and ice surfaces

    NASA Astrophysics Data System (ADS)

    Lhermitte, Stef; Abermann, Jakob; Kinnard, Christophe

    2014-05-01

    Surface albedo determines the shortwave radiation balance, arguably the largest energy balance component of snow and ice surfaces. Consequently, incorporation of the spatio-temporal variability of albedo is essential when assessing the surface energy balance of snow and ice surfaces. This can be done by using ground-based measurements or albedo data derived from remote sensing, or by modelling albedo based on radiative transfer models or empirically based parameterizations. One decisive factor when incorporating albedo data is the representativeness of surface albedo, certainly over rough surfaces where albedo measurements at a specific location (i.e., apparent albedo) can differ strongly from the material albedo or the true albedo (i.e., effective albedo) depending on the position of the sun/sensor and the surface roughness. This stresses the need for a comprehensive understanding of the effect of surface roughness on albedo and its impact when using albedo data for validation of remote sensing imagery, interpretation of automated weather station (AWS) radiation data or incorporation in energy balance models. To assess the effect of surface roughness on albedo an intra-surface radiative transfer (ISRT) model was combined with albedo measurements on a penitente field on Glaciar Tapado in the semi-arid Andes of Northern Chile. The ISRT model shows albedo reductions between 0.06 and 0.35 relative to flat surfaces with a uniform material albedo. The magnitude of these reductions primarily depends on the penitente geometry, but the shape and spatial variability of the material albedo also play a major role. Secondly, the ISRT model was used to reveal the effect of using apparent albedo to infer the effective albedo over a rough surface. This effect is especially strong for narrow penitentes, resulting in sampling biases up to ±0.05. The sampling biases are more pronounced when the sensor is low above the surface, but remain relatively constant throughout the day

  1. Albedo in the ATIC Experiment

    NASA Technical Reports Server (NTRS)

    Sokolskaya, N. V.; Adams, J. H., Jr.; Ahn, H. S.; Bashindzhagyan, G. L.; Batkov, K. E.; Case, G.; Christl, M.; Chang, J.; Fazely, A. R.; Ganel, O.; Six, N. Frank (Technical Monitor)

    2002-01-01

    ATIC(Advanced Thin Ionization Calorimeter) is a balloon borne experiment designed to measure the cosmic ray composition for elements from hydrogen to iron and their energy spectra from approx.50 GeV to near 100 TeV. It consists of a Si-matrix detector to determine the charge of a CR particle, a scintillator hodoscope for tracking, carbon interaction targets and a fully active BGO calorimeter. ATIC had its first 16-day flight from McMurdo, Antarctica from 28/12/2000 to 13/01/2000. The ATIC flight collected approximately 25 million events. To measure charge of primary particle in presence of radiation scattered back from the interaction and subsequent shower development in the calorimeter a charge detector must be a mosaic of small detector pads so that the pad containing the signal from the incident particle has no additional signal from albedo particles. Therefore the silicon matrix was built of 4480 individual silicon pads each 2 cm x 1.5 cm. The matrix consists of four planes of detectors and the active detector area, in these planes are partially overlapped to completely cover the aperture. The lateral and amplitude distributions of albedo signals in Si-matrix are analyzed for different primary nuclei and different energy deposits in BGO calorimeter. The greater part of albedo signals has Q near 1, where Q = square root of Amplitude(MIP). The albedo distribution exponentially decreases up to Q near 8. These high values are produced by slow protons and plans. There are also a small number of signals of Q > 8, mainly for heavy nucleus primaries. These signals are apparently generated by neutrons. The comparison of the experimental data and simulations with GEANT 3-21 code using QGSM generator for nucleus-nucleus interactions is presented.

  2. Compositional interpretation of the geometric albedo of asteroids. I. Solar phase effects

    NASA Astrophysics Data System (ADS)

    Carvano, J. M.

    2008-08-01

    Aims: In this first paper we investigate the dependence of the geometric albedo on the phase function of the particles that cover it, and derive the expected geometric albedo of bodies for a given mineralogy, taking into account the constraints imposed by the observed phase functions of the asteroids. Methods: A genetic fitting algorithm is used to fit Hapke integral phase functions to Lumme-Bowell integral phase functions described by values of the slope parameter G of the IAU HG system. The resulting geometric albedo of laboratory samples are then compared to the observed values of asteroids with assumed similar mineralogy. Results: Because of the weak dependence of barθ on the integral phase functions it is not possible to find a unique set of Hapke parameters that fit the Lumme-Bowell function for a given value of G, at least for phase angles <60°. Instead, unique solutions can be found if we leave barθ as a free parameter. It is shown that the laboratory derived scattering parameters in general fail to match the geometric albedo and slope parameter of asteroids of presumed equal mineralogy. It is also shown that a given value of the single scatter albedo can lead to very different values of p_v, depending on G and barθ. The methodology developed is used to compare the observed pv and G of the asteroids (4) Vesta and (21) Lutetia with laboratory measurements of materials with suposedly similar compositions. As expected, it is found that the albedo and slope parameter of Vesta are compatible with measurements of unweathered terrestrial basalts with grain sizes <= 250 μm. The albedo and slope parameter of Lutetia are found to be compatible with samples of the Allende CV3 meteorite for grain sizes <500 μm. The routines that allow the conversion between w and pV (and vice-versa) are available at http://funk.on.br/ carvano/albedo/albedo.html

  3. ANALYTIC MODELS FOR ALBEDOS, PHASE CURVES, AND POLARIZATION OF REFLECTED LIGHT FROM EXOPLANETS

    SciTech Connect

    Madhusudhan, Nikku; Burrows, Adam E-mail: burrows@astro.princeton.edu

    2012-03-01

    New observational facilities are becoming increasingly capable of observing reflected light from transiting and directly imaged extrasolar planets. In this study, we provide an analytic framework to interpret observed phase curves, geometric albedos, and polarization of giant planet atmospheres. We compute the observables for non-conservative Rayleigh scattering in homogeneous semi-infinite atmospheres using both scalar and vector formalisms. In addition, we compute phase curves and albedos for Lambertian, isotropic, and anisotropic scattering phase functions. We provide analytic expressions for geometric albedos and spherical albedos as a function of the scattering albedo for Rayleigh scattering in semi-infinite atmospheres. Given an observed geometric albedo our prescriptions can be used to estimate the underlying scattering albedo of the atmosphere, which in turn is indicative of the scattering and absorptive properties of the atmosphere. We also study the dependence of polarization in Rayleigh scattering atmospheres on the orbital parameters of the planet-star system, particularly on the orbital inclination. We show how the orbital inclination of non-transiting exoplanets can be constrained from their observed polarization parameters. We consolidate the formalism, solution techniques, and results from analytic models available in the literature, often scattered in various sources, and present a systematic procedure to compute albedos, phase curves, and polarization of reflected light.

  4. Formation of Iapetus' extreme albedo dichotomy by exogenically triggered thermal ice migration.

    PubMed

    Spencer, John R; Denk, Tilmann

    2010-01-22

    The extreme albedo asymmetry of Saturn's moon Iapetus, which is about 10 times as bright on its trailing hemisphere as on its leading hemisphere, has been an enigma for three centuries. Deposition of exogenic dark material on the leading side has been proposed as a cause, but this alone cannot explain the global shape, sharpness, and complexity of the transition between Iapetus' bright and dark terrain. We demonstrate that all these characteristics, and the asymmetry's large amplitude, can be plausibly explained by runaway global thermal migration of water ice, triggered by the deposition of dark material on the leading hemisphere. This mechanism is unique to Iapetus among the saturnian satellites because its slow rotation produces unusually high daytime temperatures and water ice sublimation rates for a given albedo.

  5. Use of albedo for neutron reflector regions in reactor core 3-D simulations

    NASA Astrophysics Data System (ADS)

    Mohanakrishnan, P.

    1989-10-01

    In this paper we present two new simplified schemes for the application of the albedo concept of replacing the reflector in 3-D reactor core simulations. Both involve the numerical derivation of albedoes from the fluxes at the core- (blanket-) reflector interface obtained from sample calculations including the reflector. Diffusion theory is used for core calculations in both cases. In the first scheme a new method for "diagonalising" the albedo matrix is demonstrated. This achieves easy applicability of the albedo parameters in core simulations of a fast breeder reactor core, resulting in significant savings in computing efforts. The second scheme, applied to light water reactors, achieves better accuracy in core periphery power predictions with the use of only uniform coarse meshes throughout the core and the numerically derived albedoes.

  6. Write field asymmetry in perpendicular magnetic recording

    NASA Astrophysics Data System (ADS)

    Li, Zhanjie; Bai, Daniel Z.; Lin, Ed; Mao, Sining

    2012-04-01

    We present a systematic study of write field asymmetry by using micromagnetic modeling for a perpendicular magnetic recording (PMR) writer structure. Parameters investigated include initial magnetization condition, write current amplitude, write current frequency, and initial write current polarity. It is found that the write current amplitude and frequency (data rate) are the dominant factors that impact the field asymmetry. Lower write current amplitude and higher write current frequency will deteriorate the write field asymmetry, causing recording performance (such as bit error rate) degradation.

  7. The Ultraviolet Albedo of Ganymede

    NASA Astrophysics Data System (ADS)

    McGrath, Melissa; Hendrix, A.

    2013-10-01

    A large set of ultraviolet images of Ganymede have been acquired with the Hubble Space Telescope over the last 15 years. These images have been used almost exclusively to study Ganymede’s stunning auroral emissions (Feldman et al. 2000; Eviatar et al. 2001; McGrath et al. 2004; Saur et al. 2011; McGrath et al. 2013), and even the most basic information about Ganymede’s UV albedo has yet to be gleaned from these data. We will present a first-cut analysis of both disk-averaged and spatially-resolved UV albedos of Ganymede, with focus on the spatially-resolved Lyman-alpha albedo, which has never been considered previously for this satellite. Ganymede's visibly bright regions are known to be rich in water ice, while the visibly dark regions seem to be more carbonaceous (Carlson et al., 1996). At Lyman-alpha, these two species should also have very different albedo values. References Carlson, R. and 39 co-authors, Near-infrared spectroscopy and spectral mapping of Jupiter and the Galilean satellites: Results from Galileo’s initial orbit, Science, 274, 385-388, 1996. Eviatar, A., D. F. Strobel, B. C. Wolven, P. D. Feldman, M. A. McGrath, and D. J. Williams, Excitation of the Ganymede ultraviolet aurora, Astrophys. J, 555, 1013-1019, 2001. Feldman, P. D., M. A. McGrath, D. F. Strobel, H. W. Moos, K. D. Retherford, and B. C. Wolven, HST/STIS imaging of ultraviolet aurora on Ganymede, Astrophys. J, 535, 1085-1090, 2000. McGrath M. A., Lellouch E., Strobel D. F., Feldman P. D., Johnson R. E., Satellite Atmospheres, Chapter 19 in Jupiter: The Planet, Satellites and Magnetosphere, ed. F. Bagenal, T. Dowling, W. McKinnon, Cambridge University Press, 2004. McGrath M. A., Jia, Xianzhe; Retherford, Kurt; Feldman, Paul D.; Strobel, Darrell F.; Saur, Joachim, Aurora on Ganymede, J. Geophys. Res., doi: 10.1002/jgra.50122, 2013. Saur, J., S. Duling, S., L. Roth, P. D. Feldman, D. F. Strobel, K. D. Retherford, M. A. McGrath, A. Wennmacher, American Geophysical Union, Fall Meeting

  8. Changes in Earth's albedo measured by satellite.

    PubMed

    Wielicki, Bruce A; Wong, Takmeng; Loeb, Norman; Minnis, Patrick; Priestley, Kory; Kandel, Robert

    2005-05-06

    NASA global satellite data provide observations of Earth's albedo, i.e., the fraction of incident solar radiation that is reflected back to space. The satellite data show that the last four years are within natural variability and fail to confirm the 6% relative increase in albedo inferred from observations of earthshine from the moon. Longer global satellite records will be required to discern climate trends in Earth's albedo.

  9. Dominance of grain size impacts on seasonal snow albedo at open sites in New Hampshire

    NASA Astrophysics Data System (ADS)

    Adolph, Alden C.; Albert, Mary R.; Lazarcik, James; Dibb, Jack E.; Amante, Jacqueline M.; Price, Andrea

    2017-01-01

    Snow cover serves as a major control on the surface energy budget in temperate regions due to its high reflectivity compared to underlying surfaces. Winter in the northeastern United States has changed over the last several decades, resulting in shallower snowpacks, fewer days of snow cover, and increasing precipitation falling as rain in the winter. As these climatic changes occur, it is imperative that we understand current controls on the evolution of seasonal snow albedo in the region. Over three winter seasons between 2013 and 2015, snow characterization measurements were made at three open sites across New Hampshire. These near-daily measurements include spectral albedo, snow optical grain size determined through contact spectroscopy, snow depth, snow density, black carbon content, local meteorological parameters, and analysis of storm trajectories using the Hybrid Single-Particle Lagrangian Integrated Trajectory model. Using analysis of variance, we determine that land-based winter storms result in marginally higher albedo than coastal storms or storms from the Atlantic Ocean. Through multiple regression analysis, we determine that snow grain size is significantly more important in albedo reduction than black carbon content or snow density. And finally, we present a parameterization of albedo based on days since snowfall and temperature that accounts for 52% of variance in albedo over all three sites and years. Our improved understanding of current controls on snow albedo in the region will allow for better assessment of potential response of seasonal snow albedo and snow cover to changing climate.

  10. Influence of tropospheric aerosol on integral albedo of cloudy atmosphere. Underlying surface system

    NASA Astrophysics Data System (ADS)

    Tarasova, T. A.; Feygelson, Y. M.

    1984-05-01

    The integral albedo which is formed for the most part due to the albedo of clouds and the underlying surface, but aerosol outside the cloud can exert an influence is discussed. The four layer system was examined. Stimulated parameters for the individual layers and stipulated albedo of the underlying surface are used in computing the spectral albedo of the cloud layer of subsystem and transmission. The albedo for the system (a formula for Asys is derived) are determined. The method reduces the problem of determining the albedo of the four layer system to three independent problems, A sub 0, A sub I, A sub II, each of which is solved in the delta-Eddington two-flux approximation on the assumption of homogeneity of the individual layers. The effect of aerosol outside the cloud is indicated. In small absorption aerosol scattering in the layers outside the clouds increases the albedo of the system as a whole. The formula for Asys and other results evaluate the aerosol effect information of the integral albedo of the system.

  11. About UV albedo of seasonal snow at Sodankyla including Arctic - Antarctic comparison aspects

    NASA Astrophysics Data System (ADS)

    Meinander, O.; Kazadzis, S.; Arola, A.; Kivi, R.; Kontu, A.; Suokanerva, H.; Kyrö, E.; Aaltonen, V.; Manninen, T.; Riihelä, A.; Roujean, J.-L.; Hautecoeur, O.

    2013-05-01

    Finland is especially advantageous for snow albedo studies, as it represents the European Arctic, the snow cover melts every year, we have five out of the six global snow classes, and the topography is flat, thus favorable to albedo studies. In 2007, new continuous broadband measurements on Arctic snow UV albedo at Sodankyla (67°22'N, 26°39'E, 179 m asl) were started by the Finnish Meteorological Institute as part of the IPY activities. Weekly snow samples have been collected for BC analyses at Sodankyla since 2009, and snow grain size data belongs to the snow time regular measurement procedures at Sodankyla as well. In literature, albedo values for clean snow in UV-VIS are 0.97-0.98, consistent with the extremely small absorption coefficient of ice in this spectral range. We have found that in case of intensively melting Arctic snow, with melt water surrounding the several millimeter snow grains, containing possibly BC up to 40 ppb and organic carbon up to 1734 ppb, and confirmed by three independent ancillary snow albedo measurements, the UV-VIS albedo of snow measured at an open snow covered field (surrounded by distant trees not shadowing the field during the measurement) can be around 0.5-0.7. For comparison, we have measured the clean Arctic Sea ice and snow at 87°N to have A = 0.91 - 0.92 both in the UV and VIS. Our experimental results on artificially sooted snow show that when albedo of natural southern Finnish snow was AVIS=0.92 and AUV=0.70, with surface EC=87 ppb, then introducing an amount of EC=4916 ppb soot on the surface of snow, decreased albedo immediately into A=0.28-0.29 in both the UV and VIS. We have also studied the SZA asymmetry of albedo found in the Arctic and Antarctic albedo data, and Radiative Transfer (RT) model calculations have been used to study e.g. the effect of the measured local albedo on radiative forcing.

  12. Using BRDFs for accurate albedo calculations and adjacency effect corrections

    SciTech Connect

    Borel, C.C.; Gerstl, S.A.W.

    1996-09-01

    In this paper the authors discuss two uses of BRDFs in remote sensing: (1) in determining the clear sky top of the atmosphere (TOA) albedo, (2) in quantifying the effect of the BRDF on the adjacency point-spread function and on atmospheric corrections. The TOA spectral albedo is an important parameter retrieved by the Multi-angle Imaging Spectro-Radiometer (MISR). Its accuracy depends mainly on how well one can model the surface BRDF for many different situations. The authors present results from an algorithm which matches several semi-empirical functions to the nine MISR measured BRFs that are then numerically integrated to yield the clear sky TOA spectral albedo in four spectral channels. They show that absolute accuracies in the albedo of better than 1% are possible for the visible and better than 2% in the near infrared channels. Using a simplified extensive radiosity model, the authors show that the shape of the adjacency point-spread function (PSF) depends on the underlying surface BRDFs. The adjacency point-spread function at a given offset (x,y) from the center pixel is given by the integral of transmission-weighted products of BRDF and scattering phase function along the line of sight.

  13. The temporal scale research of MODIS albedo product authenticity verification

    NASA Astrophysics Data System (ADS)

    Cao, Yongxing; Xue, Zhihang; Cheng, Hui; Xiong, Yajv; Chen, Yunping; Tong, Ling

    2016-06-01

    This study introduces a method that normalizes the inversed ETM+ albedo to the local solar noon albedo for the temporal scale of the MODIS albedo validation. Firstly, the statistical relation model between the surface albedo and the solar elevation angle was set up, and then deducing relationship between ETM+ albedo and the solar elevation angle, so the ETM+ albedo at local solar noon could be got. Secondly, the ground measurement albedo at the local solar noon was used to assess the inversed ETM+ albedo and the normalized albedo. The experiment results show that the method can effectively improve the accuracy of product certification.

  14. On perturbative azimuthal asymmetry at RHIC

    SciTech Connect

    Rezaeian, A. H.

    2008-10-13

    We investigate the azimuthal asymmetry of partons and photons produced at the initial stage of nuclear collisions at the RHIC energy originating from quark-nucleus collisions. In our approach, the azimuthal asymmetry results from the correlation between color dipole orientation and impact parameter of the collision. The asymmetry is sensitive to the rapid variation of the nuclear density at the nuclear periphery. We either introduce the color-dipole orientation into the improved Born approximation, or model the dipole partial amplitude which satisfies available DIS data. We conclude that the azimuthal asymmetry coming from these mechanisms can be sizable.

  15. beta. -decay asymmetry of the free neutron

    SciTech Connect

    Bopp, P.; Dubbers, D.; Klemt, E.; Last, J.; Schuetze, H.; Weibler, W.; Freedman, S.J.; Schaerpf, O.

    1983-01-01

    The ..beta..-decay of polarized neutrons has been studied with the new superconducting spectrometer PERKEO at the ILL. The energy dependence of the ..beta..-decay asymmetry has been measured for the first time. From the measured ..beta..-asymmetry parameter we obtain a new value for the ratio of weak coupling constants g/sub A//g/sub V/. 11 references.

  16. Representation of vegetation effects on the snow-covered albedo in the Noah land surface model with multiple physics options

    NASA Astrophysics Data System (ADS)

    Park, S.; Park, S. K.

    2015-04-01

    Snow albedo plays a critical role in calculating the energy budget, but parameterization of the snow surface albedo is still under great uncertainty. It varies with snow grain size, snow cover thickness, snow age, forest shading factor and other variables. Snow albedo of forest is typically lower than that of short vegetation; thus snow albedo is dependent on the spatial distributions of characteristic land cover and on the canopy density and structure. In the Noah land surface model with multiple physics options (Noah-MP), almost all vegetation types in East Asia during winter have the minimum values of leaf area index (LAI) and stem area index (SAI), which are too low and do not consider the vegetation types. Because LAI and SAI are represented in terms of photosynthetic activeness, the vegetation effect rarely exerts on the surface albedo in winter in East Asia with only these parameters. Thus, we investigated the vegetation effects on the snow-covered albedo from observations and evaluated the model improvement by considering such effect. We found that calculation of albedo without proper reflection of the vegetation effect is mainly responsible for the large positive bias in winter. Therefore, we developed new parameters, called leaf index (LI) and stem index (SI), which properly manage the effect of vegetation structure on the winter albedo. As a result, the Noah-MP's performance in albedo has been significantly improved - RMSE is reduced by approximately 73%.

  17. Quantifying surface scattering parameters for bright and dark Martian surfaces

    NASA Astrophysics Data System (ADS)

    Fox, V. K.; Arvidson, R. E.; Wolff, M. J.

    2013-12-01

    Surface single scattering albedos (SSA) and single particle phase functions from 0.45 to 2.65 micrometers were retrieved from Mars Reconnaissance Orbiter CRISM hyperspectral observations of the low albedo Syrtis Planum (FRT0000A154; 8.6 N 292.2 W) and high albedo Arabia Terra (FRT000061B3; 20.5 N, 356.7 W), i.e., non-icy albedo end members for Mars. Specifically, a multiple-scattering discrete ordinate radiative transfer package (based on DISORT) was used to explicitly model carbon dioxide, water vapor, and carbon monoxide gas bands as a function of elevation within the scene, dust and ice aerosol scattering and absorption, and the Hapke Photometric function with a two-term (asymmetry factor and forward fraction) Henyey-Greenstein (HG) single particle phase function. CRISM emission phase function observations, taken both during incoming and outgoing passes over the targeted scene, were used where the data overlapped the central scene to constrain the best fit to surface and atmospheric parameters using a non-linear least-squares approach. Initial results indicate that both bright and dark terrains are best modeled using a moderately back-scattering HG function with an asymmetry factor of ~0.26 and a forward fraction of ~0.3. SSA retrievals at ~1 micron are 0.53 and 0.78 for the Syrtis and Arabia scenes, respectively. Future work will extend these results to longer wavelengths and other scenes within the dark and bright areas to characterize in more detail these end member surfaces.

  18. Effect of atmospheric dust loading on martian albedo measurements

    NASA Astrophysics Data System (ADS)

    Zinzi, Angelo; Palomba, Ernesto; Rinaldi, Giovanna; D'Amore, Mario

    2010-08-01

    This work is devoted to the analysis of the variation of albedo measured by orbiting instruments with atmospheric opacity on Mars. The study has been conduced by analysing Mars Global Surveyor Thermal Emission Spectrometer (MGS-TES) data from martian regions with different surface albedo. In support of these data, synthetic spectra with different surface albedo and atmospheric opacities have been computed, so that a comparison has been performed. The synthetic spectra have been retrieved by using two different grain sizes for suspended dust (0.5 and 1.2 μm), allowing a comparison between the two models and the observations. Using the DCI, a parameter describing the quantity of dust deposited on the surface, the effectiveness of the single scattering approximation has been tested for low atmospheric opacity by analysing the quality of the linear fit up to different atmospheric opacity. For more opaque conditions two kinds of fits have been applied to the data, linear and second-order degree polynomial. In this case, we found that the polynomial fit better describes the observations. The analysis of these data made it possible to notice a peculiar trend, already reported by Christensen (1988), of the albedo over Syrtis Major after the occurrence of dust storms, but, differently from that work, now the study of DCI together with atmospheric opacity and albedo allowed us to robustly confirm the hypothesis made by Christensen. Finally, the comparison between observations and synthetic spectra computed with models with different particles grain sizes indicates that dust particles of 0.5 μm diameter are the most effective to change the aerosol atmospheric opacity on Mars.

  19. Albedo indicating land degradation around the Badain Jaran Desert for better land resources utilization.

    PubMed

    Liu, Fengshan; Chen, Ying; Lu, Haiying; Shao, Hongbo

    2017-02-01

    Surface albedo is an easy access parameter in reflecting the status of both human disturbed soil and indirectly influenced area, whose characteristic is an important indicator in sustainable development under the background of global climate change. In this study, we employed meteorological data, MODIS 8-day BRDF/Albedo and LAI products from 2000 to 2014 to show the amelioration and mechanism around the Badain Jaran Desert. Results showed that the human-dominated afforestation activities significantly increased the leaf area index (LAI) in summer and autumn. Lower reflectance at visible band was sensed inside the desert compared with the ecozone and the lowest albedo at forested area. The contribution of soil and vegetation reflectance to surface albedo determined the linear sensitivity of albedo to LAI variation. Decreased albedo dominated the spatial-temporal pattern of the Badain Jaran Desert. This study suggested that surface albedo can be regarded as a useful index in indicating the change process and evaluating the sustainable development of biological management around the Badain Jaran Desert.

  20. Variability of albedo and utility of the MODIS albedo product in forested wetlands

    USGS Publications Warehouse

    Sumner, David M.; Wu, Qinglong; Pathak, Chandra S.

    2011-01-01

    Albedo was monitored over a two-year period (beginning April 2008) at three forested wetland sites in Florida, USA using up- and down-ward facing pyranometers. Water level, above and below land surface, is the primary control on the temporal variability of daily albedo. Relatively low reflectivity of water accounts for the observed reductions in albedo with increased inundation of the forest floor. Enhanced canopy shading of the forest floor was responsible for lower sensitivity of albedo to water level at the most dense forest site. At one site, the most dramatic reduction in daily albedo was observed during the inundation of a highly-reflective, calcareous periphyton-covered land surface. Satellite-based Moderate-Resolution Imaging Spectroradiometer (MODIS) estimates of albedo compare favorably with measured albedo. Use of MODIS albedo values in net radiation computations introduced a root mean squared error of less than 4.7 W/m2 and a mean, annual bias of less than 2.3 W/m2 (1.7%). These results suggest that MODIS-estimated albedo values can reliably be used to capture areal and temporal variations in albedo that are important to the surface energy balance.

  1. Retrieval of the Single Scattering Albedo in the EL Paso-Juarez Airshed Using the Tuv Model and a Uv-Mfrsr Radiometer

    NASA Astrophysics Data System (ADS)

    Medina Calderon, R.; Environmental Physics At Utep

    2010-12-01

    A methodology to retrieve Single Scattering Albedo (SSA) values based in Direct to Diffuse Ratio (DDR) measurements was implemented for the El Paso-Juarez Airshed. The methodology used the TUV Model and has been applied to the measurements of a UV-MFRSR located in El Paso, Texas. The inferred SSAs at both 332 and 368 nm were higher in a clean day than in a dirty polluted day. Also, studies made about the asymmetric factor indicated that variation in the asymmetry parameter is the secondary effect on the retrievals of SSA. In summary, it was found that the TUV Model can be used as a diagnostic model to interpret UV-MFRSR Irradiance data and to successfully retrieve single scattering albedo. This methodology can be applied in any part of the country. However it is particularly useful for US Southwest cities that experience episodes of high PM concentrations.Retrieval values of SSA Values of SSA for Clean,and Dirty days with their corresponding values of Aerosol Optical Depth

  2. NEOWISE diameters and albedos: now available on PDS!

    NASA Astrophysics Data System (ADS)

    Masiero, Joseph R.; Mainzer, Amy K.; Bauer, James M.; Cutri, Roc M.; Grav, Tommy; Kramer, Emily A.; Nugent, Carolyn; Sonnett, Sarah M.; Stevenson, Rachel; Wright, Edward L.

    2016-10-01

    We present the recent PDS release of minor planet physical property data from the WISE/NEOWISE fully cryogenic, 3-band cryo, and post-cryo surveys as well as the first year of the NEOWISE-Reactivation survey. This release includes 165,865 diameters, visible albedos, near-infrared albedos, and/or beaming parameters for 140,493 unique minor planets. The published data include near-Earth asteroids, Main Belt asteroids, Hildas, Jupiter Trojans, Centaurs, active Main Belt objects and irregular satellites of Jupiter and Saturn. We provide an overview of the available data and discuss the key features of the PDS data set. The data are available online at: http://sbn.psi.edu/pds/resource/neowisediam.html.

  3. Measuring the influence of aerosols and albedo on sky polarization.

    PubMed

    Kreuter, A; Emde, C; Blumthaler, M

    2010-11-01

    All-sky distributions of the polarized radiance are measured using an automated fish-eye camera system with a rotating polarizer. For a large range of aerosol and surface albedo situations, the influence on the degree of polarization and sky radiance is investigated. The range of aerosol optical depth and albedo is 0.05-0.5 and 0.1-0.75, respectively. For this range of parameters, a reduction of the degree of polarization from about 0.7 to 0.4 was observed. The analysis is done for 90° scattering angle in the principal plane under clear sky conditions for a broadband channel of 450 ± 25 nm and solar zenith angles between 55° and 60°. Radiative transfer calculations considering three different aerosol mixtures are performed and and agree with the measurements within the statistical error.

  4. Radiation Dose from Lunar Neutron Albedo

    NASA Technical Reports Server (NTRS)

    Adams, J. H., Jr.; Bhattacharya, M.; Lin, Zi-Wei; Pendleton, G.

    2006-01-01

    The lunar neutron albedo from thermal energies to 8 MeV was measured on the Lunar Prospector Mission in 1998-1999. Using GEANT4 we have calculated the neutron albedo due to cosmic ray bombardment of the moon and found a good-agreement with the measured fast neutron spectra. We then calculated the total effective dose from neutron albedo of all energies, and made comparisons with the effective dose contributions from both galactic cosmic rays and solar particle events to be expected on the lunar surface.

  5. Algebraic method for calculating a neutron albedo

    NASA Astrophysics Data System (ADS)

    Ignatovich, V. K.; Shabalin, E. P.

    2007-02-01

    A neutron albedo from arbitrary homogeneous and finely grained substances is examined on the basis of a new, algebraic, method. In the approximation of an isotropic distribution of incident and reflected neutrons, it is shown that, in the case of thermal neutrons, coherent scattering on individual particles of finely grained media increases only slightly the transport cross section, but, at a given wall thickness, it reduces the albedo because of a decrease in the density of the substance. A significant increase in the albedo is possible only for neutrons of wavelength on the order of dimensions of a powder grain. The angular distribution of reflected neutrons is discussed, and it is proven that a deviation of this distribution from an isotropic one does not lead to a change in the magnitude of the albedo.

  6. Spatially Complete Surface Albedo Data Sets: Value-Added Products Derived from Terra MODIS Land Products

    NASA Technical Reports Server (NTRS)

    Moody, Eric G.; King, Michael D.; Platnick, Steven; Schaaf, Crystal B.; Gao, Feng

    2004-01-01

    Spectral land surface albedo is an important parameter for describing the radiative properties of the Earth. Accordingly it reflects the consequences of natural and human interactions, such as anthropogenic, meteorological, and phenological effects, on global and local climatological trends. Consequently, albedos are integral parts in a variety of research areas, such as general circulation models (GCMs), energy balance studies, modeling of land use and land use change, and biophysical, oceanographic, and meteorological studies. Recent observations of diffuse bihemispherical (white-sky) and direct beam directional hemispherical (black-sky ) land surface albedo included in the MOD43B3 product from MODIS instruments aboard NASA's Terra and Aqua satellite platforms have provided researchers with unprecedented spatial, spectral, and temporal characteristics. Cloud and seasonal snow cover, however, curtail retrievals to approximately half the global land surfaces on an annual equal-angle basis, precluding MOD43B3 albedo products from direct inclusion in some research projects and production environments.

  7. Hemispheric Asymmetries in Children.

    ERIC Educational Resources Information Center

    Lewandowski, Lawrence

    1982-01-01

    Hemispheric specialization tasks were given to different-aged boys. Asymmetries were demonstrated on manual, visual, and auditory tasks; however, the degree of asymmetries did not change across age groups. There appears to be a dissociation between visual and auditory perceptual asymmetries. (Author/RD)

  8. Empirical models of monthly and annual surface albedo in managed boreal forests of Norway

    NASA Astrophysics Data System (ADS)

    Bright, Ryan M.; Astrup, Rasmus; Strømman, Anders H.

    2013-04-01

    As forest management activities play an increasingly important role in climate change mitigation strategies of Nordic regions such as Norway, Sweden, and Finland -- the need for a more comprehensive understanding of the types and magnitude of biogeophysical climate effects and their various tradeoffs with the global carbon cycle becomes essential to avoid implementation of sub-optimal policy. Forest harvest in these regions reduces the albedo "masking effect" and impacts Earth's radiation budget in opposing ways to that of concomitant carbon cycle perturbations; thus, policies based solely on biogeochemical considerations in these regions risk being counterproductive. There is therefore a need to better understand how human disturbances (i.e., forest management activities) affect important biophysical factors like surface albedo. An 11-year remotely sensed surface albedo dataset coupled with stand-level forest management data for a variety of stands in Norway's most productive logging region are used to develop regression models describing temporal changes in monthly and annual forest albedo following clear-cut harvest disturbance events. Datasets are grouped by dominant tree species and site indices (productivity), and two alternate multiple regression models are developed and tested following a potential plus modifier approach. This resulted in an annual albedo model with statistically significant parameters that explains a large proportion of the observed variation, requiring as few as two predictor variables: i) average stand age - a canopy modifier predictor of albedo, and ii) stand elevation - a local climate predictor of a forest's potential albedo. The same model structure is used to derive monthly albedo models, with models for winter months generally found superior to summer models, and conifer models generally outperforming deciduous. We demonstrate how these statistical models can be applied to routine forest inventory data to predict the albedo

  9. Universal freezing of asymmetry

    NASA Astrophysics Data System (ADS)

    Zhang, Da-Jian; Yu, Xiao-Dong; Huang, Hua-Lin; Tong, D. M.

    2017-02-01

    Asymmetry of quantum states is a useful resource in applications such as quantum metrology, quantum communication, and reference frame alignment. However, asymmetry of a state tends to be degraded in physical scenarios where environment-induced noise is described by covariant operations, e.g., open systems constrained by superselection rules, and such degradations weaken the abilities of the state to implement quantum information processing tasks. In this paper, we investigate under which dynamical conditions asymmetry of a state is totally unaffected by the noise described by covariant operations. We find that all asymmetry measures are frozen for a state under a covariant operation if and only if the relative entropy of asymmetry is frozen for the state. Our finding reveals the existence of universal freezing of asymmetry, and provides a necessary and sufficient condition under which asymmetry is totally unaffected by the noise.

  10. Contrasting snow and ice albedos derived from MODIS, Landsat ETM+ and airborne data from Langjökull, Iceland

    NASA Astrophysics Data System (ADS)

    Pope, Ed; Willis, Ian; Pope, Allen; Miles, Evan; Arnold, Neil; Rees, Gareth

    2015-04-01

    Surface albedo is a key parameter in the energy balance of glaciers and ice sheets because it controls the shortwave radiation budget, which is often the dominant term of a glacier's surface energy balance. Monitoring surface albedo is a key application of remote sensing and achieving consistency between instruments is crucial to accurate assessment of changing albedo. These measurements may then be used to quantify past reflectance, energy balance and melt characteristics. Here we compare near contemporaneous ETM+ (30 m), MODIS (250 m) and airborne multispectral imagery (ATM; 5 m) that were collected over Langjökull, Iceland's second largest ice cap (910 km2) in 2007. All three radiance datasets are converted to reflectance by applying commonly used atmospheric correction schemes: 6S and FLAASH. These are used to derive broadband albedos. We first compare the similarity of albedo values produced by the different atmospheric correction schemes for the same instrument, then contrast results from the different instruments. In this way we are able to evaluate the consistency of the available atmospheric correction algorithms and to consider the impacts of different spatial resolutions. Albedo is shown to be highly variable at small spatial scales. Different retrieval methods for surface albedo from the same instrument are shown to produce locally inconsistent measurements of surface albedo. Differences between the atmospheric correction schemes of 6S and FLAASH therefore produce significant contrasts in surface albedo. Comparison of the 6S corrected ATM dataset, a 6S corrected ETM+ dataset and an MCD43 dataset showed inconsistencies between the datasets associated with specific glacier facies. These differences result in contrasting stepped albedo maps which would imply spatially different melt regimes across the glacier surface. These inconsistencies are hypothesised to be the result of the certainty with which sub-pixel scale differences in albedo, Bi

  11. SURFACE ALBEDO AND SPECTRAL VARIABILITY OF CERES

    SciTech Connect

    Li, Jian-Yang; Reddy, Vishnu; Corre, Lucille Le; Sykes, Mark V.; Prettyman, Thomas H.; Nathues, Andreas; Hoffmann, Martin; Schaefer, Michael; Izawa, Matthew R. M.; Cloutis, Edward A.; Carsenty, Uri; Jaumann, Ralf; Krohn, Katrin; Mottola, Stefano; Schröder, Stefan E.; Castillo-Rogez, Julie C.; Schenk, Paul; Williams, David A.; Smith, David E.; Zuber, Maria T.; and others

    2016-02-01

    Previous observations suggested that Ceres has active, but possibly sporadic, water outgassing as well as possibly varying spectral characteristics over a timescale of months. We used all available data of Ceres collected in the past three decades from the ground and the Hubble Space Telescope, as well as the newly acquired images by the Dawn  Framing Camera, to search for spectral and albedo variability on Ceres, on both a global scale and in local regions, particularly the bright spots inside the Occator crater, over timescales of a few months to decades. Our analysis has placed an upper limit on the possible temporal albedo variation on Ceres. Sporadic water vapor venting, or any possibly ongoing activity on Ceres, is not significant enough to change the albedo or the area of the bright features in the Occator crater by >15%, or the global albedo by >3% over the various timescales that we searched. Recently reported spectral slope variations can be explained by changing Sun–Ceres–Earth geometry. The active area on Ceres is less than 1 km{sup 2}, too small to cause global albedo and spectral variations detectable in our data. Impact ejecta due to impacting projectiles of tens of meters in size like those known to cause observable changes to the surface albedo on Asteroid Scheila cannot cause detectable albedo change on Ceres due to its relatively large size and strong gravity. The water vapor activity on Ceres is independent of Ceres’ heliocentric distance, ruling out the possibility of the comet-like sublimation process as a possible mechanism driving the activity.

  12. SUSY CP phases and asymmetries at colliders

    NASA Astrophysics Data System (ADS)

    Kittel, Olaf

    2009-06-01

    In the Minimal Supersymmetric Standard Model, physical phases of complex parameters lead to CP violation. We show how triple products of particle momenta or spins can be used to construct asymmetries, that allow us to probe these CP phases. To give specific examples, we discuss the production of neutralinos at the International Linear Collider (ILC). For the Large Hadron Collider (LHC), we discuss CP asymmetries in squark decays, and in the tri-lepton signal. We find that the CP asymmetries can be as large as 60%.

  13. Albedo changes occurring in stationary forest covers over France during the last decade

    NASA Astrophysics Data System (ADS)

    Planque, C.; Carrer, D.; Roujean, J. L.

    2015-12-01

    Climate warming has caused unprecedented changes in the vegetation cycle of forests. In return, forests play a substantial role on climate by directly modifying the amount of carbon dioxide in the atmosphere. Besides the shifts occurring in forest architecture and diversity, the climate pressure influences the canopy structure and the leaf physiological characteristics. A direct consequence is the modification of reflectivity properties of the whole canopy. This study examines the evolution of the direct radiative forcing due to the evolution of reflectivity properties of the canopy (canopy albedo). We restrict our analysis to the albedo trends occurring in stationary forest covers over France during the last decade (2001-2013). Satellite surface albedo, LAI (leaf area index), and FCOVER (fraction of vegetation cover) from MODIS (on Terra and Aqua satellites) and BioPar (Bio-geophysical Parameter) projects are used in order to 1/ isolate stationary forest covers, and 2/ detect local tendencies in their canopy albedo. First, the statistical tests were applied to LAI, FCOVER, and surface albedo data over the areas that are classified as forest by ESA-CCI land cover database. In case of temporal break in LAI or FCOVER data series, we assume that the forest was managed at least once during the last decade or the vegetation cover has changed. This hypothesis was verified over the Landes forest in southwestern France, where a major storm damaged 300000 hectares in 2009. This work allowed to isolate relative stationary forest covers that were not managed. Secondly, we show that the visible surface albedo has decreased due to the gradual closing and increase in greenness of some of these forest covers. Finally, we quantified the change in direct radiative forcing due to this shift of surface albedo by using ERA-Interim incoming solar radiation data. The next step will be to better characterize the physiological and structural factors that drive these albedo changes.

  14. An improved carbon dioxide snow spectral albedo model: Application to Martian conditions

    NASA Astrophysics Data System (ADS)

    Singh, D.; Flanner, M. G.

    2016-10-01

    Carbon dioxide ice is abundant on the Martian surface and plays an important role in the planet's energy budget due to its high reflectivity and seasonal variation. Here we adapt the terrestrial Snow, Ice, and Aerosol Radiation (SNICAR) model to simulate CO2 snow albedo across the ultraviolet, visible, and near-IR spectra (0.2-5.0 µm). We apply recent laboratory-derived refractive indices of CO2 ice, which produce higher broadband CO2 snow albedo (0.93-0.98) than previously estimated. Compared with H2O snow, we find that CO2 snow albedo is much higher in the near-IR spectrum, less dependent on ice grain size, less dependent on solar zenith angle, and more susceptible to darkening from dust. A mass concentration of 0.01% Martian dust reduces visible and near-IR CO2 snow albedos by about 60% and 35%, respectively. The presence of small amounts of H2O snow on top of CO2 snow can substantially decrease the surface albedo. Whereas 2.5 cm of H2O snow can completely mask the impact of underlying CO2 ice or the surface, roughly twice as much overlying CO2 snow is required to mask underlying H2O snow. Similarly, a 10% mixing ratio of H2O ice embedded in CO2 snow decreases broadband albedo by 0.18, while 10% CO2 ice elevates H2O snow broadband albedo by 0.10. We also present comparisons between hemispherical albedo produced by SNICAR and observations of directional reflectance of Martian polar ice caps. While imperfect, this best fit analysis provides general ranges of physical parameters in different Martian environments that produce reasonable model-observation agreement.

  15. Leptogenesis and gravity: Baryon asymmetry without decays

    NASA Astrophysics Data System (ADS)

    McDonald, J. I.; Shore, G. M.

    2017-03-01

    A popular class of theories attributes the matter-antimatter asymmetry of the Universe to CP-violating decays of super-heavy BSM particles in the Early Universe. Recently, we discovered a new source of leptogenesis in these models, namely that the same Yukawa phases which provide the CP violation for decays, combined with curved-spacetime loop effects, lead to an entirely new gravitational mechanism for generating an asymmetry, driven by the expansion of the Universe and independent of the departure of the heavy particles from equilibrium. In this Letter, we build on previous work by analysing the full Boltzmann equation, exploring the full parameter space of the theory and studying the time-evolution of the asymmetry. Remarkably, we find regions of parameter space where decays play no part at all, and where the baryon asymmetry of the Universe is determined solely by gravitational effects.

  16. Gamma-ray Albedo of the Moon

    SciTech Connect

    Moskalenko, Igor V.; Porter, Troy A.

    2007-06-14

    We use the GEANT4 Monte Carlo framework to calculate the gamma-ray albedo of the Moon due to interactions of cosmic ray (CR) nuclei with moon rock. Our calculation of the albedo spectrum agrees with the EGRET data. We show that the spectrum of gamma-rays from the Moon is very steep with an effective cutoff around 3 GeV (600 MeV for the inner part of the Moon disc). Since it is the only (almost) black spot in the gamma-ray sky, it provides a unique opportunity for calibration of gamma-ray telescopes, such as the forthcoming Gamma Ray Large Area Space Telescope (GLAST). The albedo flux depends on the incident CR spectrum which changes over the solar cycle. Therefore, it is possible to monitor the CR spectrum using the albedo gamma-ray flux. Simultaneous measurements of CR proton and helium spectra by the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA), and observations of the albedo -rays by the GLAST Large Area Telescope (LAT), can be used to test the model predictions and will enable the GLAST LAT to monitor the CR spectrum near the Earth beyond the lifetime of PAMELA.

  17. Asymmetry of Blinking

    PubMed Central

    Kassem, Iris S.; Evinger, Craig

    2012-01-01

    Purpose Too investigate asymmetry in eyelid movements with blinking, the stability of the asymmetry, and its modifiability in normal humans. Methods Differences in the start time and amplitude between the two eyelids were assessed for voluntary blinks and reflex blinks evoked by supraorbital trigeminal nerve stimulation. These variables were also measured before and up to 18 months after 2 hours of unilateral upper lid restraint. Results With voluntary blinks, one eyelid consistently began to close earlier and made a larger eyelid movement than the other eyelid. Stimulation of the supraorbital branch of the trigeminal nerve evoked relatively larger amplitude blinks in one eyelid that correlated with the asymmetries of voluntary blinks. There was a continuum of eyelid asymmetry across all subjects that was stable and independent of other biological asymmetries, such as handedness. Briefly reducing eyelid mobility created a long-lasting change in eyelid asymmetry with blinking. Conclusions Eyelid asymmetry results from differences in the excitability of motoneurons in the left and right facial motor nuclei and does not appear to involve asymmetries in cortical inputs to the brain stem. Because adaptive processes modify the motoneuron excitability that creates eyelid asymmetry, these processes may underlie changes in blinking associated with facial palsy and may play a role in the development of disorders that affect one side of the face, such as hemifacial spasm. PMID:16384962

  18. Asymmetries at the Tevatron

    SciTech Connect

    Bartos, Pavol

    2014-10-28

    In this report, we summarize the latest results of the top-quark pair production asymmetry and present the new result of bottom-quark pair production asymmetry. By looking at the results obtained by the CDF experiment, one can see a discrepancy in both $t\\bar{t}$ inclusive and lepton-based measurements. The D0 results of the $t\\bar{t}$ production asymmetry are compatible with the standard-model predictions as well as with the CDF results. The CDF measurement of $b\\bar{b}$ production asymmetry presents consistency with both zero and with the standard-model predictions.

  19. The ultraviolet continuum albedo of Uranus

    SciTech Connect

    Cochran, W.D.; Wagener, R.; Caldwell, J.; Fricke, K.H. New York State Univ., Stony Brook York Univ., Toronto Bonn Universitaet )

    1990-01-01

    A radiative transfer code explicitly treating the Raman scattering of solar protons by H{sub 2} is presently used to analyze the Uranus geometric albedo in the 2000-5000 A range. The Baines and Bergstralh (1986) baseline model used reproduces the geometric albedo peak produced by Raman scattering filling of solar absorption line cores, but is found to be excessively bright for wavelengths below 2400 A. This discrepancy is resolvable through inclusion of an absorbing stratospheric haze layer, and results are thereby obtained which are consistent with the Pollack et al. (1987) model, in which aerosols are generated stratospherically through photochemical effects on hydrocarbons. 20 refs.

  20. The diameter and albedo of 1943 Anteros

    NASA Technical Reports Server (NTRS)

    Veeder, G. J.; Tedesco, E. F.; Tholen, D. J.; Tokunaga, A.; Matthews, K.; Neugebauer, G.; Soifer, B. T.; Kowal, C.

    1981-01-01

    The results of broadband visual and infrared photometry of the Apollo-Amor asteroid 1943 Anteros during its 1980 apparition are reported. By means of a radiometric model, a diameter of 2.3 + or - 0.2 km and a visual geometric albedo of 0.13 + or - 0.03 is calculated. The albedo and reflectance spectrum of Anteros imply that it is a type S asteroid. Thus, Anteros may have a silicate surface similar to other Apollo-Amor asteroids as well as some stony-iron meteorites.

  1. Ground albedo neutrons produced by cosmic radiations

    NASA Astrophysics Data System (ADS)

    Kodama, M.

    1983-05-01

    Day-to-day variations of cosmic-ray-produced neutron fluxes near the earth's ground surface are measured by using three sets of paraffin-moderated BF3 counters, which are installed in different locations, 3 m above ground, ground level, and 20 cm under ground. Neutron flux decreases observed by these counters when snowcover exists show that there are upward-moving neutrons, that is, ground albedo neutron near the ground surface. The amount of albedo neutrons is estimated to be about 40 percent of total neutron flux in the energy range 1-10 to the 6th eV.

  2. Linking the fPAR, forest albedo and biomass in the northern biomes of Europe

    NASA Astrophysics Data System (ADS)

    Lukeš, Petr; Stenberg, Pauline; Manninen, Terhikki; Rautiainen, Miina; Mõttus, Matti

    2014-05-01

    Land surface albedo and the fraction of photosynthetically active radiation (fPAR) absorbed by plant canopies are two of the essential climate variables controlling the planetary radiative energy budget. Albedo is directly related to the energy exchange between land and the atmosphere as it is the reflectivity of the surface - the higher the albedo, the more incoming solar radiation is reflected and the less absorbed by the surface. The fPAR is related to plant productivity, quantifying the amount of absorbed light available for photosynthesis. It is a key parameter in the modelling of net primary production (NPP) of terrestrial ecosystems. Global climate scenarios are very sensitive to albedo and fPAR estimates, and thus, the effect of changes in canopy structure and density (biomass) on these two variables needs to be quantified reliably. Both parameters are routinely retrieved from current Earth Observation sensors using specialized algorithms. To date, these satellite products have not been linked to extensive forest inventory data sets due to the lack of ground reference data. Data availability for Finland has significantly improved in December 2012, when National Forest Inventory (NFI) data became freely available to the public. The dataset covers the geographical area of Finland (26.1 million hectares) at a spatial resolution of 20 meters including several forest structural variables. In this study, we use the NFI data to study the links between forest albedo, fPAR and forest structure and density during the green vegetation season. More specifically, we investigated the seasonal trends in fPAR and albedo of different spectral regions of northern forests. Empirical relationships between forest albedo, fPAR and total aboveground biomass were established for selected days within the vegetation growing period and across a latitudinal transect of Finland.

  3. The determination of surface albedo from meteorological satellites

    NASA Technical Reports Server (NTRS)

    Johnson, W. T.

    1977-01-01

    A surface albedo was determined from visible data collected by the NOAA-4 polar orbiting meteorological satellite. To filter out the major cause of atmospheric reflectivity, namely clouds, techniques were developed and applied to the data resulting in a map of global surface albedo. Neglecting spurious surface albedos for regions with persistent cloud cover, sun glint effects, insufficient reflected light and, at this time, some unresolved influences, the surface albedos retrieved from satellite data closely matched those of a global surface albedo map produced from surface and aircraft measurements and from characteristic albedos for land type and land use.

  4. Using albedo to reform wind erosion modelling, mapping and monitoring

    NASA Astrophysics Data System (ADS)

    Chappell, Adrian; Webb, Nicholas P.

    2016-12-01

    Wind erosion and dust emission models are used to assess the impacts of dust on radiative forcing in the atmosphere, cloud formation, nutrient fertilisation and human health. The models are underpinned by a two-dimensional geometric property (lateral cover; L) used to characterise the three-dimensional aerodynamic roughness (sheltered area or wakes) of the Earth's surface and calibrate the momentum it extracts from the wind. We reveal a fundamental weakness in L and demonstrate that values are an order of magnitude too small and significant aerodynamic interactions between roughness elements and their sheltered areas have been omitted, particularly under sparse surface roughness. We describe a solution which develops published work to establish a relation between sheltered area and the proportion of shadow over a given area; the inverse of direct beam directional hemispherical reflectance (black sky albedo; BSA). We show direct relations between shadow and wind tunnel measurements and thereby provide direct calibrations of key aerodynamic properties. Estimation of the aerodynamic parameters from albedo enables wind erosion assessments over areas, across platforms from the field to airborne and readily available satellite data. Our new approach demonstrated redundancy in existing wind erosion models and thereby reduced model complexity and improved fidelity. We found that the use of albedo enabled an adequate description of aerodynamic sheltering to characterise fluid dynamics and predict sediment transport without the use of a drag partition scheme (Rt) or threshold friction velocity (u∗t). We applied the calibrations to produce global maps of aerodynamic properties which showed very similar spatial patterns to each other and confirmed the redundancy in the traditional parameters of wind erosion modelling. We evaluated temporal patterns of predicted horizontal mass flux at locations across Australia which revealed variation between land cover types that would not

  5. Measurement of branching fraction and time-dependent CP asymmetry parameters in B0→D*+D*-KS0 decays

    NASA Astrophysics Data System (ADS)

    Dalseno, J.; Adachi, I.; Aihara, H.; Aushev, T.; Bakich, A. M.; Balagura, V.; Bay, A.; Bitenc, U.; Bizjak, I.; Bozek, A.; Bračko, M.; Browder, T. E.; Chao, Y.; Chen, A.; Cheon, B. G.; Chistov, R.; Cho, I.-S.; Choi, Y.; Choi, Y. K.; Danilov, M.; Dash, M.; Drutskoy, A.; Eidelman, S.; Go, A.; Ha, H.; Hayasaka, K.; Hazumi, M.; Heffernan, D.; Hokuue, T.; Hyun, H. J.; Inami, K.; Ishikawa, A.; Ishino, H.; Iwasaki, M.; Iwasaki, Y.; Joshi, N. J.; Kah, D. H.; Kang, J. H.; Kapusta, P.; Katayama, N.; Kawai, H.; Kawasaki, T.; Kichimi, H.; Kim, H. J.; Kim, Y. J.; Kinoshita, K.; Križan, P.; Krokovny, P.; Kumar, R.; Kuo, C. C.; Kuzmin, A.; Kwon, Y.-J.; Lee, J. S.; Lee, S. E.; Lesiak, T.; Li, J.; Limosani, A.; Lin, S.-W.; Liventsev, D.; Mandl, F.; Matsumoto, T.; McOnie, S.; Medvedeva, T.; Mitaroff, W.; Miyake, H.; Miyata, H.; Moloney, G. R.; Nakano, E.; Nakao, M.; Nishida, S.; Nitoh, O.; Ogawa, S.; Ohshima, T.; Okuno, S.; Onuki, Y.; Ostrowicz, W.; Ozaki, H.; Pakhlov, P.; Pakhlova, G.; Park, C. W.; Park, H.; Park, K. S.; Pestotnik, R.; Piilonen, L. E.; Sahoo, H.; Sakai, Y.; Schneider, O.; Schümann, J.; Seidl, R.; Sekiya, A.; Senyo, K.; Sevior, M. E.; Shapkin, M.; Shibuya, H.; Singh, J. B.; Sokolov, A.; Somov, A.; Stanič, S.; Starič, M.; Stoeck, H.; Sumisawa, K.; Sumiyoshi, T.; Takasaki, F.; Tanaka, M.; Taylor, G. N.; Teramoto, Y.; Tian, X. C.; Tsukamoto, T.; Uehara, S.; Ueno, K.; Uglov, T.; Unno, Y.; Uno, S.; Urquijo, P.; Varner, G.; Villa, S.; Vinokurova, A.; Wang, C. C.; Wang, C. H.; Watanabe, Y.; Wedd, R.; Won, E.; Yabsley, B. D.; Yamaguchi, A.; Yamashita, Y.; Yamauchi, M.; Zhang, Z. P.; Zhilich, V.; Zupanc, A.

    2007-10-01

    We present a measurement of the branching fraction and time-dependent CP violation parameters for B0→D*+D*-KS0 decays. These results are obtained from a 414fb-1 data sample that contains 449×106 BB¯ pairs collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. We obtain the branching fraction, B(B0→D*+D*-KS0)=[3.4±0.4(stat)±0.7(syst)]×10-3, which is in agreement with the current world average. We also obtain an upper limit on the product branching fraction for a possible two-body decay, B(B0→Ds1+(2536)D*-)B(Ds1+(2536)→D*+KS0)<7.1×10-4 (90% CL). In the traditional 2-parameter time-dependent CP analysis, we measure the CP violation parameters, ACP=-0.01-0.28+0.28(stat)±0.09(syst), Dsin⁡2ϕ1=0.06-0.44+0.45(stat)±0.06(syst). No evidence for either mixing-induced or direct CP violation is found. In a 3-parameter fit sensitive to cos⁡2ϕ1 performed in the half-Dalitz spaces, s-≤s+ and s->s+, where s±≡m2(D*±KS0), we extract the CP violation parameters, Jc/J0=0.60-0.28+0.25(stat)±0.08(syst), 2Js1/J0sin⁡2ϕ1=-0.17-0.42+0.42(stat)±0.09(syst), 2Js2/J0cos⁡2ϕ1=-0.23-0.41+0.43(stat)±0.13(syst). A large value of Jc/J0 would indicate a significant resonant contribution from a broad unknown Ds**+ state. Although the sign of the factor, 2Js2/J0, can be deduced from theory, no conclusion can be drawn regarding the sign of cos⁡2ϕ1 given the errors.

  6. Albedo of a Dissipating Snow Cover.

    NASA Astrophysics Data System (ADS)

    Robinson, David A.; Kukla, George

    1984-12-01

    Albedos of surfaces covered with 50 cm of fresh dry snow following a major U.S. East Coast storm on 11-12 February 1983 ranged from 0.20 over a mixed coniferous forest to 0.80 over open farmland. As the snow cover dissipated, albedo decreased in a quasi-linear fashion over forests. It dropped rapidly at first, then slowly, over shrubland; while the opposite was observed over farmland.Following the melt, the albedo of snowfree surfaces ranged from 0.07 over a predominantly wet peat field to 0.20 over a field covered with corn stubble and yellow grass. The difference between snow-covered and snowfree albedo was 0.72 over the peaty field and 0.10 over the mixed forest.Visible band (0.28-0.69 m) reflectivities of snow-covered fields and shrubland were higher than those in the near-infrared (0.69-2.80 m), whereas the opposite was true over mixed coniferous forests. Visible and near-infrared reflectivities were approximately equal over deciduous forests.Data were collected in a series of low-altitude flights between 10 February and 24 March 1984 in northern New Jersey and southeastern New York with Eppley hemispheric pyranometers mounted on the wingtip of a Cessna 172 aircraft.

  7. Albedo Accuracy Impact On Evapotranspiration Estimation

    NASA Astrophysics Data System (ADS)

    Mattar, C.; Franch, B.; Sobrino, J. A.; Corbari, C.; Jimenez-Munoz, J. C.; Olivera, L.; Skerbaba, D.; Soria, G.; Oltra-Carrio, R.; Julien, Y.; Manchini, M.

    2013-12-01

    In this work, we analyze the influence of estimating the land surface albedo directly from the surface reflectance or through the BRDF integration in the estimation of energy balance components such as the net radiation, latent and heat flux and consequently in the land surface evapotranspiration. To this end, we processed remote sensing and in-situ meteorological data measured at the agricultural test site of Barrax in the framework of Earth Observation: optical Data calibration and Information eXtraction (EODIX) project. Remote sensing images were acquisitioned for different View Zenith Angles (VZA) by the Airborne Hyperspectral Images (AHS). Results have shown that albedo estimations derived from BRDF model present stability through every image while albedo estimations using single reflectance presented high variation depending on the VZA. The highest difference was observed in the backward scattering direction along the hot spot region obtaining a RMSE of 0.11 through the AHS image which implied a relative error of 65%. This work has analyzed the error committed by many evapotranspiration studies that assume the surface as Lambertian and estimate the albedo from a surface reflectance weighted average.

  8. Albedos of Centaurs, Jovian Trojans and Hildas

    NASA Astrophysics Data System (ADS)

    Romanishin, William

    2017-01-01

    I present optical V band albedo distributions for samples of outer solar system minor bodies including Centaurs, Jovian Trojans and Hildas. Diameters come almost entirely from the NEOWISE catalog (Mainzer etal 2016- Planetary Data System). Optical photometry (H values) for about 2/3 of the approximately 2700 objects studied are from PanStarrrs (Veres et al 2015 Icarus 261, 34). The PanStarrs optical photometry is supplemented by H values from JPL Horizons (corrected to be on the same photometric system as the PanStarrs data) for the objects in the NEOWISE catalog that are not in the PanStarrs catalog. I compare the albedo distributions of various pairs of subsamples using the nonparametric Wilcoxon rank sum test. Examples of potentially interesting comparisons include: (1) the median L5 Trojan cloud albedo is about 10% darker than that of the L4 cloud at a high level of statistical significance and (2) the median albedo of the gray Centaurs lies between that of the L4 and L5 Trojan groups.

  9. Neutron albedo imager for land mine detection

    NASA Astrophysics Data System (ADS)

    McFee, John E.; Andrews, H. Robert; Ing, Harry; Cousins, Thomas; Faust, Anthony A.; Haslip, Dean S.

    2002-08-01

    Neutron albedo land mine detection involves irradiating the ground with fast neutrons and subsequently detecting the thermalized neutrons which return. This technique has been studied since the 1950's, but only using non-imaging detectors. Without imaging, natural variations in hydrogen content in the soil, chiefly due to moisture, and surface irregularities, produce enough false alarms to render the method impractical in all but the driest conditions. This paper describes research to design and build a prototype landmine detector based on neutron albedo imaging. Realistic Monte Carlo simulations were performed to assess the signal-to-noise ratio for various soil types and moisture contents, assuming a perfect two dimensional neutron imaging system. The study showed that a neutron albedo imager was feasible for mine detection and that image quality could be good enough to significantly improve detector performance and reduce false alarm rates compared to non-imaging albedo detection, particularly in moist soils and where surface irregularities exist. After reviewing various neutron detector technologies, a design concept was developed. It consisted of a novel thermal neutron imaging system, a unique neutron source to uniformly irradiate the underlying ground and hardware and software for image generation and enhancement. Performance capability, including spatial resolution and detection times, were estimated by modeling. A proof-of-principle imager is now being constructed with an expected completion date of Spring 2002. The detector design is described and preliminary results are discussed.

  10. Fluctuating Asymmetry and Intelligence

    ERIC Educational Resources Information Center

    Bates, Timothy C.

    2007-01-01

    The general factor of mental ability ("g") may reflect general biological fitness. If so, "g"-loaded measures such as Raven's progressive matrices should be related to morphological measures of fitness such as fluctuating asymmetry (FA: left-right asymmetry of a set of typically left-right symmetrical body traits such as finger…

  11. Albedo boundaries on Mars in 1972: Results from Mariner 9

    USGS Publications Warehouse

    Batson, R.M.; Inge, J.L.

    1976-01-01

    A map of "albedo" boundaries (light and dark markings) on Mars was prepared from Mariner 9 images. After special digital processing, these pictures provide detailed locations of albedo boundaries, which is significant in interpreting recent eolian activity. Derivation of absolute albedo values from the spacecraft data was not attempted. The map correlates well with telescopic observations of Mars after the 1971 dust storm. ?? 1976.

  12. Use of the MSA products as an adequate representation of the surface albedo in the ALADIN-Belgium NWP model

    NASA Astrophysics Data System (ADS)

    Bertrand, C.; Govaerts, Y.; Clerbaux, N.; Ipe, A.; Gonzalez, L.

    2003-04-01

    Land surface albedo represents the proportion of the incoming radiative flux reflected by the surface. It is highly variable in space and time over terrestrial surfaces and plays a key role in surface-atmosphere interaction processes. In particular, it is used in numerical weather forecast and climate models to parametrize surface boundary radiative conditions. Hence, the accurate knowledge of surface albedo at the appropriate time and space scales is essential in estimating radiation balance components. Unfortunately, surface albedo in numerical models is commonly prescribed from low-resolution seasonal data sets. Such data sets are often based on limited ground-based albedo observations and information on surface and vegetation types, even though such approaches do not accurately account for the actual structural effects of the underlying surface. To account for the high spatial and temporal variability of the surface albedo, the ALADIN-Belgium NWP model has been initialized with the directional hemispherical reflectance generated by the Meteosat Surface Albedo (MSA) algorithm. The MSA product is generated every 10 days with a spatial resolution close to the 7 km mesh size of ALADIN-Belgium NWP model. A number of sensitivity forecast runs using the MSA products has shown a significant improvement of the simulated radiative fluxes with respect to simulations performed with a surface albedo derived from climatological values of soil and vegetation parameters. This finding suggests that the use of the high-resolution MSA products could also be valuable for improving model temperature forecasts.

  13. Application and Evaluation of MODIS LAI, fPAR, and Albedo Products in the WRFCMAQ System

    EPA Science Inventory

    Leaf area index (LAI), vegetation fraction (VF), and surface albedo are important parameters in the land surface model (LSM) for meteorology and air quality modeling systems such as WRF/CMAQ. LAI and VF control not only leaf to canopy level evapotranspiration flux scaling but al...

  14. Lowering of Asymmetry

    NASA Astrophysics Data System (ADS)

    Pandey, K. K.; Hiremath, K. M.; Yellaiah, G.

    2017-03-01

    Asymmetry, a well established fact, can be extracted from various solar atmospheric activity indices. Although asymmetry is being localized within short time scale, it also persists at different time scales. In the present study we examine the character and nature of asymmetry at various time scales by optimizing the data set, in units of Carrington Rotations (CRs), for Sunspot Area (SA) and soft X-ray flare index (FI SXR). We find from three solar cycles (21-23) that at a small time scale (viz., daily, CRs and monthly) activity appears to be asymmetric with less significance. At larger time scales (≥01 CRs) strength of asymmetry enhances. Number of significant asymmetry points probably depends upon the solar heights. For different combination of data, asymmetry strength appears to be lowered at certain periods ˜06, ˜12, ˜18 CRs (164, 327 and 492 days i.e., harmonics of ˜1.3 years. Owing to similar behavior of emergence of magnetic flux, it is conjectured that emergence of flux on the surface probably contributes to the asymmetry of the solar activity.

  15. Spatially Complete Global Spectral Surface Albedos: Value-Added Datasets Derived from Terra MODIS Land Products

    NASA Technical Reports Server (NTRS)

    Moody, Eric G.; King, Michael D.; Platnick, Steven; Schaaf, Crystal B.; Gao, Feng

    2004-01-01

    Land surface albedo is an important parameter in describing the radiative properties of the earth s surface as it represents the amount of incoming solar radiation that is reflected from the surface. The amount and type of vegetation of the surface dramatically alters the amount of radiation that is reflected; for example, croplands that contain leafy vegetation will reflect radiation very differently than blacktop associated with urban areas. In addition, since vegetation goes through a growth, or phenological, cycle, the amount of radiation that is reflected changes over the course of a year. As a result, albedo is both temporally and spatially dependant upon global location as there is a distribution of vegetated surface types and growing conditions. Land surface albedo is critical for a wide variety of earth system research projects including but not restricted to remote sensing of atmospheric aerosol and cloud properties from space, ground-based analysis of aerosol optical properties from surface-based sun/sky radiometers, biophysically-based land surface modeling of the exchange of energy, water, momentum, and carbon for various land use categories, and surface energy balance studies. These projects require proper representation of the surface albedo s spatial, spectral, and temporal variations, however, these representations are often lacking in datasets prior to the latest generation of land surface albedo products.

  16. Intercomparison of MODIS Albedo Retrievals and In Situ Measurements Across the Global FLUXNET Network

    NASA Technical Reports Server (NTRS)

    Cescatti, Alessandro; Marcolla, Barbara; Vannan, Suresh K. Santhana; Pan, Jerry Yun; Roman, Miguel O.; Yang, Xiaoyuan; Ciais, Philippe; Cook, Robert B.; Law, Beverly E.; Matteucci, Girogio; Migliavacca, Mirco; Moors, Eddy; Richardson, Andrew D.; Seufert, Guenther; Schaaf, Crystal B.

    2012-01-01

    Surface albedo is a key parameter in the Earth's energy balance since it affects the amount of solar radiation directly absorbed at the planet surface. Its variability in time and space can be globally retrieved through the use of remote sensing products. To evaluate and improve the quality of satellite retrievals, careful intercomparisons with in situ measurements of surface albedo are crucial. For this purpose we compared MODIS albedo retrievals with surface measurements taken at 53 FLUXNET sites that met strict conditions of land cover homogeneity. A good agreement between mean yearly values of satellite retrievals and in situ measurements was found (R(exp 2)= 0.82). The mismatch is correlated to the spatial heterogeneity of surface albedo, stressing the relevance of land cover homogeneity when comparing point to pixel data. When the seasonal patterns of MODIS albedo is considered for different plant functional types, the match with surface observation is extremely good at all forest sites. On the contrary, in non-forest sites satellite retrievals underestimate in situ measurements across the seasonal cycle. The mismatch observed at grasslands and croplands sites is likely due to the extreme fragmentation of these landscapes, as confirmed by geostatistical attributes derived from high resolution scenes.

  17. Multilayer surface albedo for face recognition with reference images in bad lighting conditions.

    PubMed

    Lai, Zhao-Rong; Dai, Dao-Qing; Ren, Chuan-Xian; Huang, Ke-Kun

    2014-11-01

    In this paper, we propose a multilayer surface albedo (MLSA) model to tackle face recognition in bad lighting conditions, especially with reference images in bad lighting conditions. Some previous researches conclude that illumination variations mainly lie in the large-scale features of an image and extract small-scale features in the surface albedo (or surface texture). However, this surface albedo is not robust enough, which still contains some detrimental sharp features. To improve robustness of the surface albedo, MLSA further decomposes it as a linear sum of several detailed layers, to separate and represent features of different scales in a more specific way. Then, the layers are adjusted by separate weights, which are global parameters and selected for only once. A criterion function is developed to select these layer weights with an independent training set. Despite controlled illumination variations, MLSA is also effective to uncontrolled illumination variations, even mixed with other complicated variations (expression, pose, occlusion, and so on). Extensive experiments on four benchmark data sets show that MLSA has good receiver operating characteristic curve and statistical discriminating capability. The refined albedo improves recognition performance, especially with reference images in bad lighting conditions.

  18. Spatially Complete Surface Albedo Data Sets: Value-Added Products Derived from Terra MODIS Land Products

    NASA Technical Reports Server (NTRS)

    Moody, E. G.; King, M. D.; Platnick, S.; Schaaf, C. B.; Gao, F.

    2004-01-01

    Spectral land surface albedo is an important parameter for describing the radiative properties of the Earth. Accordingly it reflects the consequences of natural and human interactions, such as anthropogenic, meteorological, and phenological effects, on global and local climatological trends. Consequently, albedos are integral parts in a variety of research areas, such as general circulation models (GCMs), energy balance studies, modeling of land use and land use change, and biophysical, oceanographic, and meteorological studies. The availability of global albedo data over a large range of spectral channels and at high spatial resolution has dramatically improved with the launch of the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument aboard NASA s Earth Observing System (EOS) Terra spacecraft in December 1999. However, lack of spatial and temporal coverage due to cloud and snow effects can preclude utilization of official products in production and research studies. We report on a technique used to fill incomplete MOD43 albedo data sets with the intention of providing complete value-added maps. The technique is influenced by the phenological concept that within a certain area, a pixel s ecosystem class should exhibit similar growth cycle events over the same time period. The shape of an area s phenological temporal curve can be imposed upon existing pixel-level data to fill missing temporal points. The methodology will be reviewed by showcasing 2001 global and regional results of complete albedo and NDVl data sets.

  19. Measurement of time dependent CP asymmetry parameters in B0 meson decays to omegaKs, etaprimeKz, and pi0Ks

    SciTech Connect

    Aubert, : B.

    2008-09-10

    The authors present measurements of the time-dependent CP-violation parameters S and C in the decays B{sup 0} {yields} {omega}K{sub S}{sup 0}, B{sup 0} {yields} {eta}{prime}K{sup 0}, reconstructed as {eta}{prime}K{sub S}{sup 0} and {eta}{prime}K{sub L}{sup 0}, and B{sup 0} {yields} {pi}{sup 0}K{sub S}{sup 0}. The data sample corresponds to the full BABAR dataset of 467 x 10{sup 6} B{bar B} pairs produced at the PEP-II asymmetric-energy e{sup +}e{sup -} collider at the Stanford Linear Accelerator Center. The results are S{sub {omega}K{sub S}{sup 0}} = 0.55{sub -0.29}{sup +0.26} {+-} 0.02, C{sub {omega}K{sub S}{sup 0}} = -0.52{sub -0.20}{sup +0.22} {+-} 0.03, S{sub {eta}{prime}K{sup 0}} = 0.57 {+-} 0.08 {+-} 0.02, C{sub {eta}{prime}K{sup 0}} = -0.08 {+-} 0.06 {+-} 0.02, S{sub {pi}{sup 0}K{sub S}{sup 0}} = 0.55 {+-} 0.20 {+-} 0.03, and C{sub {pi}{sup 0}K{sub S}{sup 0}} = 0.13 {+-} 0.13 {+-} 0.03, where the first errors are statistical and the second systematic. These results are consistent with the previous measurements and the world average of sin2{beta} measured in B{sup 0} {yields} J/{psi}K{sub S}{sup 0}.

  20. Lunar Regolith Albedos Using Monte Carlos

    NASA Technical Reports Server (NTRS)

    Wilson, T. L.; Andersen, V.; Pinsky, L. S.

    2003-01-01

    The analysis of planetary regoliths for their backscatter albedos produced by cosmic rays (CRs) is important for space exploration and its potential contributions to science investigations in fundamental physics and astrophysics. Albedos affect all such experiments and the personnel that operate them. Groups have analyzed the production rates of various particles and elemental species by planetary surfaces when bombarded with Galactic CR fluxes, both theoretically and by means of various transport codes, some of which have emphasized neutrons. Here we report on the preliminary results of our current Monte Carlo investigation into the production of charged particles, neutrons, and neutrinos by the lunar surface using FLUKA. In contrast to previous work, the effects of charm are now included.

  1. Diameters and albedos of satellites of Uranus

    NASA Technical Reports Server (NTRS)

    Brown, R. H.; Cruikshank, D. P.; Morrison, D.

    1982-01-01

    Products of the masses of the five known satellites of Uranus, and estimates of their bulk densities and surface albedos, are used to infer their probable dimensions. Spectrophotometry has established the presence of water ice on the surfaces of all save Rhea, and the brightnesses of the satellites have been measured photoelectrically. The diameter measurements presented were made using a photometric/radiometric technique, whose recent recalibration, using independent solar system object measurements, has yielded absolute accuracies better than 5 per cent. The new albedo measurements show that Umbriel, Titania and Oberon are similar to the Jupiter moon Callisto, while Ariel resembles the Saturn moon Hyperion. The diameters of all four are similar to those of the large, icy Saturn satellites Rhea and Iapetus.

  2. Earth Albedo and the orbit of LAGEOS

    NASA Technical Reports Server (NTRS)

    Rubincam, D. P.; Weiss, N. R.

    1985-01-01

    The long-period perturbations in the orbit of the Lageos satellite due to the Earth's albedo have been found using a new analytical formalism. The Earth is assumed to be a sphere whose surface diffusely reflects sunlight according to Lambert's law. Specular reflection is not considered. The formalism is based on spherical harmonics; it produces equations which hold regardless of whether the terminator is seen by the satellite or not. Specializing to the case of a realistic zonal albedo shows that Lageos' orbital semimajor axis changes periodically by only the a few millimeters and the eccentricity by one part in 100,000. The longitude of the node increases secularly. The effect considered here can explain neither the secular decay of 1.1 mm/day in the semimajor axis nor the observed along-track variations in acceleration of order 2 x 10 to the minus 12 power/sq ms.

  3. Albedo climatology analysis and the determination of fractional cloud cover

    NASA Technical Reports Server (NTRS)

    Curran, R. J.; Wexler, R.; Nack, M. L.

    1978-01-01

    Monthly and zonally averaged surface cover climatology data are presented which are used to construct monthly and zonally averaged surface albedos. The albedo transformations are then applied to the surface albedos, using solar zenith angles characteristic of the Nimbus 6 satellite local sampling times, to obtain albedos at the top of clear and totally cloud covered atmospheres. These albedos are then combined with measured albedo data to solve for the monthly and zonally averaged fractional cloud cover. The measured albedo data were obtained from the wide field of view channels of the Nimbus 6 Earth Radiation Budget experiment, and consequently the fractional cloud cover results are representative of the local sampling times. These fractional cloud cover results are compared with recent studies. The cloud cover results not only show peaks near the intertropical convergence zone, but the monthly migration of the position of these peaks follows general predictions of atmospheric circulation studies.

  4. Estimating big bluestem albedo from directional reflectance measurements

    NASA Technical Reports Server (NTRS)

    Irons, J. R.; Ranson, K. J.; Daughtry, C. S. T.

    1988-01-01

    Multidirectional reflectance factor measurements acquired in the summer of 1986 are used to make estimates of big bluestem grass albedo, evaluating the variation of albedo with changes in solar zenith angle and phenology. On any given day, the albedo was observed to increase by at least 19 percent as solar zenith angle increased. Changes in albedo were found to correspond to changes in the green leaf area index of the grass canopy. Estimates of albedo made using reflectance data acquired within only one or two azimuthal planes and at a restricted range of view zenith angle were evaluated and compared to 'true' albedos derived from all available reflectance factor data. It was found that even a limited amount of multiple direction reflectance data was preferable to a single nadir reflectance factor for the estimation of prarie grass albedo.

  5. High Resolution Mapping of Pluto's Albedo Distribution

    NASA Astrophysics Data System (ADS)

    Stern, S.

    1994-01-01

    This proposal requests time to map Pluto's albedo distribution, using the highest possible resolution of the CYCLE 4 HST. Maps will be made in several key UV and visible bandpasses. Our scientific objectives are to (a) study the distribution of light and dark areas, (b) make the first disk-resolved estimates of Pluto's limb darkening, and (c) compositional discriminate pure from contaminated frost regions. These objectives have not been previously achievable, but are essential to understanding the surface morphology, volatile transport, and the root cause of Pluto's secular lightcurve variations. It may also be possible to detect evidence of the reported limb haze layer(s) in Pluto's atmosphere. These maps will also provide the first direct check on Pluto maps made through indirect techniques. Owing to Pluto's elliptic orbit, we expect the distribution of albedo to change (on a years-to-decade timescale) as Pluto draws away from perihelion and volatile transport proceeds. The proposed observations will document the albedo state at three rotational epochs near the time of perihelion. These maps will be obtained in two colors, by the FOC. No other astronomical instrument has sufficient resolution to accomplish these important scientific objectives.

  6. Charred Forests Increase Snow Albedo Decay: Watershed-Scale Implications of the Postfire Snow Albedo Effect

    NASA Astrophysics Data System (ADS)

    Gleason, K. E.; Nolin, A. W.

    2014-12-01

    Recent work shows that after a high severity forest fire, approximately 60% more solar radiation reaches the snow surface due to the reduction in canopy density. Also, significant amounts of black carbon (BC) particles and larger burned woody debris (BWD) are shed from standing charred trees, which concentrate on the snowpack, darken its surface, and reduce snow albedo by 50% during ablation. The postfire forest environment drives a substantial increase in net shortwave radiation at the snowpack surface, driving earlier and more rapid melt, however hydrologic models do not explicitly incorporate forest fire disturbance effects to snowpack dynamics. In this study we characterized, parameterized, and validated the postfire snow albedo effect: how the deposition and concentration of charred forest debris decreases snow albedo, increases snow albedo decay rates, and drives an earlier date of snow disappearance. For three study sites in the Oregon High Cascade Mountains, a 2-yr old burned forest, a 10-yr burned forest, and a nearby unburned forest, we used a suite of empirical data to characterize the magnitude and duration of the postfire effect to snow albedo decay. For WY 2012, WY2013, and WY2014 we conducted spectral albedo measurements, snow surface sampling, in-situ snow and meteorological monitoring, and snow energy balance modeling. From these data we developed a new parameterization which represents the postfire effect to snow albedo decay as a function of days-since-snowfall. We validated our parameterization using a physically-based, spatially-distributed snow accumulation and melt model, in-situ snow monitoring, net snowpack radiation, and remote sensing data. We modeled snow dynamics across the extent of all burned area in the headwaters of the McKenzie River Basin and validated the watershed-scale implications of the postfire snow albedo effect using in-situ micrometeorological and remote sensing data. This research quantified the watershed scale postfire

  7. The hemispherical asymmetry in the Martian polar caps

    NASA Technical Reports Server (NTRS)

    Lindner, Bernhard L.

    1993-01-01

    An energy balance model is used to study the behavior of CO2 ice on Mars. The effect of the solar zenith angle dependence of albedo is to lengthen CO2 ice lifetimes at the poles. Hemispherical asymmetries in cloud and dust abundance could result in the survival of seasonal CO2 ice through summer in the south and not in the north, in agreement with observations. CO2 ice observed in the summertime polar cap in the south could be of recent origin, although a permanent CO2 polar cap cannot be ruled out.

  8. Analysis of regional albedo characteristics and its influence in the regional climate model REMO

    NASA Astrophysics Data System (ADS)

    Preuschmann, S.; Jacob, D.

    2010-09-01

    The effects of land-use changes on climate have a high priority in climate impact researches. Nevertheless it is not trivial to integrate land-use changes in the Regional atmospherical climate Model REMO (Jacob 2001) so that characteristics of a typical land-use type can be created and therewith systematical effects can be analyzed. As in many regional dynamical climate models, REMO is calculating in the target resolution with parameters which are independent of land-use classes. Considering only one of these parameters, e.g. the albedo, the processing chain (Rechid et al. 2008) to construct the underlying model-albedo uses a number of assumptions which levels phase and amplitude of the albedo-cycle of a regional typical land cover. The albedo data product ALBEDOMAP (Fischer et al. 2006) of the Medium Resolution Imaging Spectrometer (MERIS) on the ESA platform ENVISAT is used as comparative data set. The annual cycle of the ALBEDOMAP data exceeds the modeled variability of the annual albedo cycle permanently in some cases by a factor of ten. Results of REMO-sensitivity studies show, that even small changes in the albedo about one percent is influencing the simulation. Within this study the relevance of characteristically surface information concerning land-use change for fine resolutions in REMO were shown. Fischer, J. ; Preusker, R.; Muller, J.-P. & M. Zühlke (2007): ALBEDOMAP -Validation Report - ESA AO/1-4559/04/I-LG, Online-Publikation: http://www.brockmann-consult.de/albedomap/pdf/MERIS-AlbedoMap-Validation-1.0.pdf. Jacob, D. (2001): A note to the simulation of the annual and inter-annual variability of the water budget over the Baltic Sea drainage basin; Meteorol. Amtos. Phys., 77, 61-73, 2001. Rechid, D.; Raddatz, T. & D. Jacob (2008): Parameterization of snow-free land surface albedo as a function of vegetation phenology based on MODIS data and applied in climate modelling.; Theor. Appl. Climatol., DOI 10.1007/s00704-008-0003-y.

  9. Average Path-Length Parameter of Diffuse Light in Scattering Media

    NASA Astrophysics Data System (ADS)

    Arancibia-Bulnes, Camilo A.; Ruiz-Suárez, Jesús C.

    1999-03-01

    We use Monte Carlo simulations to study in detail the propagation of light in a plane-parallel medium containing scattering particles. In particular, we compute the forward and backward average path-length parameters (FAPP and BAPP, respectively) of four-flux radiative transfer models as functions of the optical depth. Strong dependence on the single scattering albedo and phase function asymmetry is found for both quantities. In general the values of the FAPP decrease with increasing absorption, whereas the opposite occurs for the BAPP. A similar effect is produced when changing from isotropic phase functions to phase functions with a large asymmetry in the forward direction. We present analytical results for the asymptotic values of the FAPP and BAPP as functions of albedo for the particular case of isotropic scattering. Our results differ markedly from the predictions obtained recently with two multiple-scattering models by Vargas and Niklasson J. Opt. Soc. Am. A 14, 2243 (1997); Appl. Opt. 36, 3735 (1997) . The differences found point out the intrinsic limitations of these models.

  10. Quality assessment and improvement of the EUMETSAT Meteosat Surface Albedo Climate Data Record

    NASA Astrophysics Data System (ADS)

    Lattanzio, A.; Fell, F.; Bennartz, R.; Trigo, I. F.; Schulz, J.

    2015-10-01

    Surface albedo has been identified as an important parameter for understanding and quantifying the Earth's radiation budget. EUMETSAT generated the Meteosat Surface Albedo (MSA) Climate Data Record (CDR) currently comprising up to 24 years (1982-2006) of continuous surface albedo coverage for large areas of the Earth. This CDR has been created within the Sustained, Coordinated Processing of Environmental Satellite Data for Climate Monitoring (SCOPE-CM) framework. The long-term consistency of the MSA CDR is high and meets the Global Climate Observing System (GCOS) stability requirements for desert reference sites. The limitation in quality due to non-removed clouds by the embedded cloud screening procedure is the most relevant weakness in the retrieval process. A twofold strategy is applied to efficiently improve the cloud detection and removal. The first step consists of the application of a robust and reliable cloud mask, taking advantage of the information contained in the measurements of the infrared and visible bands. Due to the limited information available from old radiometers, some clouds can still remain undetected. A second step relies on a post-processing analysis of the albedo seasonal variation together with the usage of a background albedo map in order to detect and screen out such outliers. The usage of a reliable cloud mask has a double effect. It enhances the number of high-quality retrievals for tropical forest areas sensed under low view angles and removes the most frequently unrealistic retrievals on similar surfaces sensed under high view angles. As expected, the usage of a cloud mask has a negligible impact on desert areas where clear conditions dominate. The exploitation of the albedo seasonal variation for cloud removal has good potentialities but it needs to be carefully addressed. Nevertheless it is shown that the inclusion of cloud masking and removal strategy is a key point for the generation of the next MSA CDR release.

  11. Quality assessment and improvement of the EUMETSAT Meteosat Surface Albedo Climate Data Record

    NASA Astrophysics Data System (ADS)

    Lattanzio, A.; Fell, F.; Bennartz, R.; Trigo, I. F.; Schulz, J.

    2015-07-01

    Surface albedo has been identified as an important parameter for understanding and quantifying the Earth's radiation budget. EUMETSAT generated the Meteosat Surface Albedo (MSA) Climate Data Record (CDR) currently comprising up to 24 years (1982-2006) of continuous surface albedo coverage for large areas of the Earth. This CDR has been created within the Sustained and Coordinated Processing of Environmental Satellite Data for Climate Monitoring (SCOPE-CM) framework. The long-term consistency of the MSA CDR is high and meets the Global Climate Observing System (GCOS) stability requirements for desert reference sites. The limitation in quality due to non removed clouds by the embedded cloud screening procedure is the most relevant weakness in the retrieval process. A twofold strategy is applied to efficiently improve the cloud detection and removal. A first step consists on the application of a robust and reliable cloud mask taking advantage of the information contained in the measurements of the infrared and visible bands. Due to the limited information available from old radiometers some clouds can still remain undetected. A second step relies on a post processing analysis of the albedo seasonal variation together with the usage of a background albedo map in order to detect and screen out such outliers. The usage of a reliable cloud mask has a double effect. It enhances the number of high quality retrievals for tropical forest areas sensed under low view angles and removes the most frequently unrealistic retrievals on similar surfaces sensed under high view angles. As expected, the usage of a cloud mask has a negligible impact on desert areas where clear conditions dominate. The exploitation of the albedo seasonal variation for cloud removal has good potentialities but it needs to be carefully addressed. Nevertheless it is shown that the inclusion of cloud masking and removal strategy is a key point for the generation of the next MSA CDR Release.

  12. Spatially Complete Global Surface Albedos Derived from Terra/MODIS Data

    NASA Technical Reports Server (NTRS)

    King, Michael D.; Moody, Eric G.; Schaaf, Crystal B.; Platnick, Steven

    2006-01-01

    Spectral land surface albedo is an important parameter for describing the radiative properties of the Earth. Accordingly it reflects the consequences of natural and human interactions, such as anthropogenic, meteorological, and phenological effects, on global and local climatological trends. Consequently, albedos are integral parts in a variety of research areas, such as general circulation models (GCMs), energy balance studies, modeling of land use and land use change, and biophysical, oceanographic, and meteorological studies. , Over five years of land surface anisotropy, diffuse bihemispherical (white-sky) albedo and direct beam directional hemispherical (black-sky) albedo from observations acquired by the MODIS instruments aboard NASA s Terra and Aqua satellite platforms have provided researchers with unprecedented spatial, spectral, and temporal information on the land surface s radiative characteristics. However, roughly 30% of the global land surface, on an annual equal-angle basis, is obscured due to persistent and transient cloud cover, while another 207% is obscured due to ephemeral and seasonal snow effects. This precludes the MOD43B3 albedo products from being directly used in some remote sensing and ground-based applications, climate models, and global change research projects. To provide researchers with the requisite spatially complete global snow-free land surface albedo dataset, an ecosystem-dependent temporal interpolation technique was developed to fill missing or lower quality data and snow covered values from the official MOD43B3 dataset with geophysically realistic values. The method imposes pixel-level and local regional ecosystem-dependent phenological behavior onto retrieved pixel temporal data in such a way as to maintain pixel-level spatial and spectral detail and integrity. The phenological curves are derived from statistics based on the MODIS MOD12Q1 IGBP land cover classification product geolocated with the MOD43B3 data.

  13. Sizes and albedos of the larger asteroids

    NASA Technical Reports Server (NTRS)

    Morrison, D.

    1977-01-01

    The purpose of the present paper is to review all asteroid diameter measurements, current through mid-1976, and to combine them in a consistent way to give the best available estimates for a sample totalling 187 objects. From these diameters it is possible to determine the size-distributions of minor planets down to diameters of 50 km in the inner belt and 100 km in the outer belt. The associated albedos further indicate the distribution of objects of the C, S, and M classes throughout the belt.

  14. Widespread Albedo Decreasing and Induced Melting of Himalayan Snow and Ice in the Early 21st Century

    PubMed Central

    Ming, Jing; Wang, Yaqiang; Du, Zhencai; Zhang, Tong; Guo, Wanqin; Xiao, Cunde; Xu, Xiaobin; Ding, Minghu; Zhang, Dongqi; Yang, Wen

    2015-01-01

    Background The widely distributed glaciers in the greater Himalayan region have generally experienced rapid shrinkage since the 1850s. As invaluable sources of water and because of their scarcity, these glaciers are extremely important. Beginning in the twenty-first century, new methods have been applied to measure the mass budget of these glaciers. Investigations have shown that the albedo is an important parameter that affects the melting of Himalayan glaciers. Methodology/Principal Findings The surface albedo based on the Moderate Resolution Imaging Spectroradiometer (MODIS) data over the Hindu Kush, Karakoram and Himalaya (HKH) glaciers is surveyed in this study for the period 2000–2011. The general albedo trend shows that the glaciers have been darkening since 2000. The most rapid decrease in the surface albedo has occurred in the glacial area above 6000 m, which implies that melting will likely extend to snow accumulation areas. The mass-loss equivalent (MLE) of the HKH glacial area caused by surface shortwave radiation absorption is estimated to be 10.4 Gt yr-1, which may contribute to 1.2% of the global sea level rise on annual average (2003–2009). Conclusions/Significance This work probably presents a first scene depicting the albedo variations over the whole HKH glacial area during the period 2000–2011. Most rapidly decreasing in albedo has been detected in the highest area, which deserves to be especially concerned. PMID:26039088

  15. Nuclear asymmetry enthalpy

    SciTech Connect

    Sobotka, L. G.

    2011-07-15

    Recent work has sought to extract the asymmetry energy at very low density from observables in heavy-ion collisions. The logic employed starts from the assumption that the fragment yields are determined by a minimization of the Helmholtz free energy. As volume is in reality unconstrained, nor can a single freeze-out volume be expected, the physical relevance of the Helmholtz free energy must be questioned. If, for example, the identical logic were used, but the Gibbs free energy was the more relevant quantity to minimize, it would be the asymmetry enthalpy that would be extracted. The purpose of this report is to provide one measure of the difference between the asymmetry energy and enthalpy.

  16. CP asymmetries in semiinclusive B0 decays

    SciTech Connect

    Dunietz, I.

    1999-02-01

    It was recently pointed out that inclusive B^0(t) decays could show CP violation. The totally inclusive asymmetry is expected to be tiny [O(10^{-3})] because of large cancellations among the asymmetries in the charmless, single charm and double charm final states. Enriching particular final state configurations could significantly increase the CP-asymmetry and observability. Such studies can extract fundamental CKM (Cabibbo-Kobayashi-Maskawa) parameters, and (perhaps) even Delta m(B_s). A superb vertex detector could see CP violation with 10^5 (10^6) flavor-tagged B_s (B_d) mesons within the CKM model. Because the effects could be significantly larger due to new physics, they should be searched for in existing or soon available data samples.

  17. Albedo maps of Pluto and Charon - Initial mutual event results

    NASA Technical Reports Server (NTRS)

    Buie, Marc W.; Tholen, David J.; Horne, Keith

    1992-01-01

    By applying the technique of maximum entropy image reconstruction to invert observed lightcurves, surface maps of single-scattering albedo are obtained for the surfaces of Pluto and Charon from 1954 to 1986. The albedo features of the surface of Pluto are similar to those of the Buie and Tholen (1989) spot model maps; a south polar cap is evident. The map of Charon is somewhat darker, with single-scattering albedos as low as 0.03.

  18. RECTIFIED ASTEROID ALBEDOS AND DIAMETERS FROM IRAS AND MSX PHOTOMETRY CATALOGS

    SciTech Connect

    Ryan, Erin Lee; Woodward, Charles E. E-mail: chelsea@astro.umn.ed

    2010-10-15

    Rectified diameters and albedo estimates of 1517 main-belt asteroids selected from IRAS and the Mid-Course Space Experiment asteroid photometry catalogs are derived from updated infrared thermal models, the Standard Thermal Model and the Near-Earth Asteroid Thermal Model (NEATM), and Monte Carlo simulations, using new Minor Planet Center compilations of absolute magnitudes (H values) constrained by occultation- and radar-derived parameters. The NEATM approach produces a more robust estimate of albedos and diameters, yielding albedos of p{sub v} (NEATM mean) =0.081 {+-} 0.064. The asteroid beaming parameter ({eta}) for the selected asteroids has a mean value of 1.07 {+-} 0.27, and the smooth distribution of {eta} suggests that this parameter is independent of asteroid properties such as composition. No trends in {eta} due to size-dependent rotation rates are evident. Comparison of derived values of {eta} as a function of taxonomic type indicates that the beaming parameter values for S- and C-type asteroids are identical within the standard deviation of the population of beaming parameters.

  19. THE ALBEDO-COLOR DIVERSITY OF TRANSNEPTUNIAN OBJECTS

    SciTech Connect

    Lacerda, Pedro; Rengel, Miriam; Fornasier, Sonia; Lellouch, Emmanuel; Delsanti, Audrey; Kiss, Csaba; Vilenius, Esa; Müller, Thomas; Santos-Sanz, Pablo; Duffard, René; Guilbert-Lepoutre, Aurélie

    2014-09-20

    We analyze albedo data obtained using the Herschel Space Observatory that reveal the existence of two distinct types of surface among midsized trans-Neptunian objects. A color-albedo diagram shows two large clusters of objects, one redder and higher albedo and another darker and more neutrally colored. Crucially, all objects in our sample located in dynamically stable orbits within the classical Kuiper Belt region and beyond are confined to the bright red group, implying a compositional link. Those objects are believed to have formed further from the Sun than the dark neutral bodies. This color-albedo separation is evidence for a compositional discontinuity in the young solar system.

  20. Enhancement of the MODIS Daily Snow Albedo Product

    NASA Technical Reports Server (NTRS)

    Hall, Dorothy K.; Schaaf, Crystal B.; Wang, Zhuosen; Riggs, George A.

    2009-01-01

    The MODIS daily snow albedo product is a data layer in the MOD10A1 snow-cover product that includes snow-covered area and fractional snow cover as well as quality information and other metadata. It was developed to augment the MODIS BRDF/Albedo algorithm (MCD43) that provides 16-day maps of albedo globally at 500-m resolution. But many modelers require daily snow albedo, especially during the snowmelt season when the snow albedo is changing rapidly. Many models have an unrealistic snow albedo feedback in both estimated albedo and change in albedo over the seasonal cycle context, Rapid changes in snow cover extent or brightness challenge the MCD43 algorithm; over a 16-day period, MCD43 determines whether the majority of clear observations was snow-covered or snow-free then only calculates albedo for the majority condition. Thus changes in snow albedo and snow cover are not portrayed accurately during times of rapid change, therefore the current MCD43 product is not ideal for snow work. The MODIS daily snow albedo from the MOD10 product provides more frequent, though less robust maps for pixels defined as "snow" by the MODIS snow-cover algorithm. Though useful, the daily snow albedo product can be improved using a daily version of the MCD43 product as described in this paper. There are important limitations to the MOD10A1 daily snow albedo product, some of which can be mitigated. Utilizing the appropriate per-pixel Bidirectional Reflectance Distribution Functions (BRDFs) can be problematic, and correction for anisotropic scattering must be included. The BRDF describes how the reflectance varies with view and illumination geometry. Also, narrow-to-broadband conversion specific for snow on different surfaces must be calculated and this can be difficult. In consideration of these limitations of MOD10A1, we are planning to improve the daily snow albedo algorithm by coupling the periodic per-pixel snow albedo from MCD43, with daily surface ref|outanoom, In this paper, we

  1. Entrainment, Drizzle, and Stratocumulus Cloud Albedo

    NASA Technical Reports Server (NTRS)

    Ackerman, A. S.; Kirkpatrick, M. P.; Stevens, D. E.; Toon, O. B.

    2004-01-01

    Globally averaged cloud changes from GCMs on average show a doubling of the Twomey effect, which is the change in cloud albedo with respect to changes in droplet concentrations for fixed cloud water and droplet dispersion. In contrast, ship-track measurements show a much more modest amplification of the Twomey effect, suggesting that the GCMs are exaggerating the indirect aerosol effect. We have run large-eddy simulations with bin microphysics of marine stratocumulus from multiple field campaigns, and find that the large-eddy simulations are in much better agreement with the ship-track measurements. The inversion strength over N. Pacific stratocumulus (as measured during DYCOMS-II) is generally much stronger than over N. Atlantic stratocumulus (as measured during ASTEX), and we have found that the response of cloud water to increasing droplet concentration changes sign as the inversion strengthens. For the different environmental conditions, we will show the overall response of cloud albedo to droplet concentrations, and decompose the response into its contributing factors of changes in cloud water, droplet dispersion, and horizontal inhomogeneity.

  2. The Very Low Albedo of an Extrasolar Planet: MOST Space-based Photometry of HD 209458

    NASA Astrophysics Data System (ADS)

    Rowe, Jason F.; Matthews, Jaymie M.; Seager, Sara; Miller-Ricci, Eliza; Sasselov, Dimitar; Kuschnig, Rainer; Guenther, David B.; Moffat, Anthony F. J.; Rucinski, Slavek M.; Walker, Gordon A. H.; Weiss, Werner W.

    2008-12-01

    Measuring the albedo of an extrasolar planet provides insight into its atmospheric composition and its global thermal properties, including heat dissipation and weather patterns. Such a measurement requires very precise photometry of a transiting system, fully sampling many phases of the secondary eclipse. Space-based optical photometry of the transiting system HD 209458 from the MOST (Microvariablity and Oscillations of Stars) satellite, spanning 14 and 44 days in 2004 and 2005, respectively, allows us to set a sensitive limit on the optical eclipse of the hot exosolar giant planet in this system. Our best fit to the observations yields a flux ratio of the planet and star of 7 +/- 9 ppm (parts per million), which corresponds to a geometric albedo through the MOST bandpass (400-700 nm) of Ag = 0.038 +/- 0.045. This gives a 1 σ upper limit of 0.08 for the geometric albedo and a 3 σ upper limit of 0.17. HD 209458b is significantly less reflective than Jupiter (for which Ag would be about 0.5). This low geometric albedo rules out the presence of bright reflective clouds in this exoplanet's atmosphere. We determine refined parameters for the star and exoplanet in the HD 209458 system based on a model fit to the MOST light curve. MOST is a Canadian Space Agency mission, operated jointly by Dynacon, Inc., and the Universities of Toronto and British Columbia, with assistance from the University of Vienna.

  3. TRANSVERSITY SINGLE SPIN ASYMMETRIES.

    SciTech Connect

    BOER,D.

    2001-04-27

    The theoretical aspects of two leading twist transversity single spin asymmetries, one arising from the Collins effect and one from the interference fragmentation functions, are reviewed. Issues of factorization, evolution and Sudakov factors for the relevant observables are discussed. These theoretical considerations pinpoint the most realistic scenarios towards measurements of transversity.

  4. From Regional Cloud-Albedo to a Global Albedo Footprint - Studying Aerosol Effects on the Radiation Budget Using the Relation Between Albedo and Cloud Fraction

    NASA Astrophysics Data System (ADS)

    Bender, F.; Engström, A.; Karlsson, J.; Wood, R.; Charlson, R. J.

    2015-12-01

    Earth's albedo is the primary determinant of the amount of energy absorbed by the Earth-atmosphere system. The main factor controlling albedo is the amount of clouds present, but aerosols can affect and alter both clear-sky and cloudy-sky reflectance. How albedo depends on cloud fraction and how albedo varies at a given cloud fraction and a given cloud water content, reveals information about these aerosol effects on the radiation budget. Hence, the relation between total albedo and cloud fraction can be used for illustration and quantification of aerosol effects, and as a diagnostic tool, to test model performance. Here, we show examples of the utilisation of this relation focusing on satellite observations from CERES and MODIS on Aqua, as well as from Calipso and CloudSat, and performing comparisons with climate models on the way: In low-cloud regions in the subtropics, we find that climate models well represent a near-constant regional cloud albedo, and this representation has improved from CMIP3 to CMIP5. CMIP5 models indicate more reflective clouds in present-day climate than pre-industrial, as a result of increased aerosol burdens. On monthly mean time scale, models are found to over-estimate the regional cloud-brightening due to aerosols. On the global scale we find an increasing cloud albedo with increasing cloud fraction - a relation that is very well defined in observations, and less so in CMIP5 models. Cloud brightening from pre-industrial to present day is also seen on global scale. Further, controlling for both cloud fraction and cloud water content we can trace small variations in albedo, or perturbations of solar reflectivity, that create a near-global coherent geographical pattern that is consistent with aerosol impacts on climate, with albedo enhancement in regions dominant of known aerosol sources and suppression of albedo in regions associated with high rates of aerosol removal (deduced using CloudSat precipitation estimates). This mapping can be

  5. Surface Albedo Variations Across Opportunity's Traverse in Meridiani Planum

    NASA Astrophysics Data System (ADS)

    Studer-Ellis, G. L.; Rice, M. S.; Johnson, J. R.; Bell, J. F., III

    2015-12-01

    Surface albedo measurements from the Mars Exploration Rover (MER) Opportunity mission can be used to help understand surface-atmosphere interactions at Meridiani Planum. Opportunity has acquired 117 albedo panoramas with the Pancam instrument as of sol 3870, across the first 40 km of its traverse. To date, only the first 32 panoramas have been reported upon in previous studies [1]. Here we present an analysis of the full set of PDS-released albedo observations from Opportunity and correlate our measurements with terrain type and known atmospheric events. To acquire a 360-degree albedo observation, Pancam's L1 ("clear") filter is used to take 27 broad-spectrum images, which are stitched into a mosaic. Pancam images are calibrated to reflectance factor (R*), which is taken as an approximation of the Lambertian albedo. Areas of interest are selected and average albedo calculations are applied to all of the selections. Results include the average albedo of each scene, as well as equal-area corrections where applicable, in addition to measurements of specific classes of surface features (e.g., outcrops, dusty terrain, and rover tracks). Average scene albedo measurements range from 0.11 ± 0.04 to 0.30 ± 0.04, with the highest value observed on sol 1290 (immediately after the planet-encircling dust storm of 2007). We compare these results to distance traveled, surface morphologies, local wind driven events, and dust opacity measurements. Future work will focus on correlating Pancam albedo values with orbital data from cameras such as HiRISE, CTX, MOC, THEMIS-VIS, and MARCI, and completion of the same analysis for the full Pancam albedo dataset from Spirit. References: [1] Bell, J. F., III, M. S. Rice, J. R. Johnson, and T. M. Hare (2008), Surface albedo observations at Gusev Crater and Meridiani Planum, Mars, J. Geophys. Res., 113, E06S18, doi:10.1029/2007JE002976.

  6. Early signs of brain asymmetry.

    PubMed

    Corballis, Michael C

    2013-11-01

    A new study shows a leftward asymmetry of the choroid plexus in two-thirds of first-trimester human fetuses. This is the earliest brain asymmetry so far identified and may be a precursor to other asymmetries, including that of the temporal planum, which is evident from the 31st week of gestation.

  7. Parameterization of the snow-covered surface albedo in the Noah-MP Version 1.0 by implementing vegetation effects

    NASA Astrophysics Data System (ADS)

    Park, Sojung; Park, Seon Ki

    2016-03-01

    Snow-covered surface albedo varies depending on many factors, including snow grain size, snow cover thickness, snow age, forest shading factor, etc., and its parameterization is still under great uncertainty. For the snow-covered surface condition, albedo of forest is typically lower than that of short vegetation; thus snow albedo is dependent on the spatial distributions of characteristic land cover and on the canopy density and structure. In the Noah land surface model with multiple physics options (Noah-MP), almost all vegetation types in East Asia during winter have the minimum values of leaf area index (LAI) and stem area index (SAI), which are too low and do not consider the vegetation types. Because LAI and SAI are represented in terms of photosynthetic activeness, stem and trunk in winter are not well represented with only these parameters. We found that such inadequate representation of the vegetation effect is mainly responsible for the large positive bias in calculating the winter surface albedo in the Noah-MP. In this study, we investigated the vegetation effect on the snow-covered surface albedo from observations and improved the model performance by implementing a new parameterization scheme. We developed new parameters, called leaf index (LI) and stem index (SI), which properly manage the effect of vegetation structure on the snow-covered surface albedo. As a result, the Noah-MP's performance in the winter surface albedo has significantly improved - the root mean square error is reduced by approximately 69 %.

  8. Measurements of Time-Dependent CP-Asymmetry Parameters in B Meson Decays to η' K0 and of Branching Fractions of SU(3) Related Modes with BaBar Experiment at SLAC

    SciTech Connect

    Biassoni, Pietro

    2009-01-01

    In this thesis work we have measured the following upper limits at 90% of confidence level, for B meson decays (in units of 10-6), using a statistics of 465.0 x 106 B$\\bar{B}$ pairs: β(B0 → ηK0) < 1.6 β(B0 → ηη) < 1.4 β(B0 → η'η') < 2.1 β(B0 → ηΦ) < 0.52 β(B0 → ηω) < 1.6 β(B0 → η'Φ) < 1.2 β(B0 → η'ω) < 1.7 We have no observation of any decay mode, statistical significance for our measurements is in the range 1.3-3.5 standard deviation. We have a 3.5σ evidence for B → ηω and a 3.1 σ evidence for B → η'ω. The absence of observation of the B0 → ηK0 open an issue related to the large difference compared to the charged mode B+ → ηK+ branching fraction, which is measured to be 3.7 ± 0.4 ± 0.1 [118]. Our results represent substantial improvements of the previous ones [109, 110, 111] and are consistent with theoretical predictions. All these results were presented at Flavor Physics and CP Violation (FPCP) 2008 Conference, that took place in Taipei, Taiwan. They will be soon included into a paper to be submitted to Physical Review D. For time-dependent analysis, we have reconstructed 1820 ± 48 flavor-tagged B0 → η'K0 events, using the final BABAR statistic of 467.4 x 106 B$\\bar{B}$ pairs. We use these events to measure the time-dependent asymmetry parameters S and C. We find S = 0.59 ± 0.08 ± 0.02, and C = -0.06 ± 0.06 ± 0.02. A non-zero value of C would represent a directly CP non-conserving component in B0 → η'K0, while S would be equal to sin2β measured in B0 → J/ΨKs0 [108], a mixing-decay interference effect, provided the decay is dominated by amplitudes of a single weak phase. The new measured value of S can be considered in agreement with the expectations of the

  9. Greenland surface albedo changes 1981-2012 from satellite observations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Significant melt over Greenland has been observed during the last several decades associated with extreme warming events over the northern Atlantic Ocean. An analysis of surface albedo change over Greenland is presented, using a 32-year consistent satellite albedo product from the Global Land Surfac...

  10. Anthropogenic desertification by high-albedo pollution Observations and modeling

    NASA Technical Reports Server (NTRS)

    Otterman, J.; Rosenberg, N. W.; Rosenberg, E.

    1974-01-01

    ERTS-1 MSS albedo data of Western Negev, Sinai and the Gaza strip are presented. A sharp contrast in albedo exists across the Negev-Sinai and Negev-Gaza strip borders. Anthropogenic desertification has occurred on the Arab side due to overgrazing and Bedouin agriculture, whereas natural vegetation grows much more abundantly on the Israeli side.

  11. Effect of shaddock albedo addition on the properties of frankfurters.

    PubMed

    Shan, Bing; Li, Xingmin; Pan, Teng; Zheng, Limin; Zhang, Hao; Guo, Huiyuan; Jiang, Lu; Zhen, Shaobo; Ren, Fazheng

    2015-07-01

    To explore the potential as a natural auxiliary emulsifier, shaddock albedo was added into frankfurters at six different levels: 0.0, 2.5, 5.0, 7.5, 10 and 12.5 %. The emulsion capacity (EC) of meat batters and cooking properties of frankfurters were evaluated. EC of meat batters was improved with the addition of shaddock albedo and the maximum value was reached at the 5 % albedo concentration. The addition of shaddock albedo resulted in lower cooking losses of frankfurters, with the lowest value obtained at the 7.5 % level. The presence of shaddock albedo decreased the total expressible fluid (TEF) and the proportion of fat in total expressible fluid (PF) which indicated the emulsion stability of frankfurters and the lowest values both occurred at the concentration of 7.5 %. Shaddock albedo inclusion increased the lightness and yellowness of frankfurters and decreased redness. Texture profile analysis showed increased hardness and decreased chewiness of frankfurters with the addition of shaddock albedo. Consequently, shaddock albedo could be a potential source of auxiliary emulsifier filler for emulsion-type meat products.

  12. Solar Radiation Management, Cloud Albedo Enhancement

    NASA Astrophysics Data System (ADS)

    Salter, Stephen H.

    Cloud albedo enhancement is one of several possible methods of solar radiation management by which the rate of increase in world temperatures could be reduced or even reversed. It depends on a well-known phenomenon in atmospheric physics known as the Twomey effect. Twomey argued that the reflectivity of clouds is a function of the size distribution of the drops in the cloud top. In clean mid-ocean air masses, there is a shortage of the condensation nuclei necessary for initial drop formation in addition to high relative humidity. This means that the liquid water in a cloud has to be in relatively large drops. If extra nuclei could be artificially introduced, the same amount of liquid water would be shared among a larger number of smaller drops which would have a larger surface area to reflect a larger fraction of the incoming solar energy back out to space.

  13. Neutrino helicity asymmetries in leptogenesis

    SciTech Connect

    Bento, Luis; Santos, Francisco C.

    2005-05-01

    It is pointed out that the heavy singlet neutrinos characteristic of leptogenesis develop asymmetries in the abundances of the two helicity states as a result of the same mechanism that generates asymmetries in the standard lepton sector. Neutrinos and standard leptons interchange asymmetries in collisions with each other. It is shown that an appropriate quantum number, B-L{sup '}, combining baryon, lepton and neutrino asymmetries, is not violated as fast as the standard B-L. This suppresses the washout effects relevant for the derivation of the final baryon asymmetry. One presents detailed calculations for the period of neutrino thermal production in the framework of the singlet seesaw mechanism.

  14. Global color and albedo variations on Io

    USGS Publications Warehouse

    McEwen, A.S.

    1988-01-01

    Three multispectral mosaics of Io have been produced from Voyager imaging data: a global mosaic from each of the Voyager 1 and Voyager 2 data sets and a high-resolution mosaic of the region surrounding the volcano Ra Patera. The mosaics are maps of normal albedo and color in accurate geometric map formats. Io's photometric behavior, mapped with a two-image technique, is spatially variable, especially in the bright white areas. The disk-integrated color and albedo of the satellite have been remarkably constant over recent decades, despite the volcanic activity and the many differences between Voyager 1 and 2 images (acquired just 4 months apart). This constancy is most likely due to the consistent occurrence of large Pele-type plumes with relatively dark, red deposits in the region from long 240 to 360??. A transient brightening southeast of Pele during the Voyager 1 encounter was probably due to real changes in surface and/or atmospheric materials, rather than to photometric behavior. The intrinsic spectral variability of Io, as seen in a series of two-dimensional histograms of the multispectral mosaics, consists of continuous variation among three major spectral end members. The data were mapped into five spectral units to compare them with laboratory measurements of candidate surface materials and to show the planimetric distributions. Unit 1 is best fit by the spectral reflectance of ordinary elemental sulfur, and it is closely associated with the Peletype plume deposits. Unit 2 is strongly confined to the polar caps above about latitude ??50??, but its composition is unknown. Unit 5 is probably SO2 with relatively minor contamination; it is concentrated in the equatorial region and near the long-lived Prometheus-type plumes. Units 3 and 4 are gradational between units 1 and 5. In addition to SO2 and elemental sulfur, other plausible components of the surface are polysulfur oxides, FeCl2, Na2S, and NaHS. ?? 1988.

  15. Asymmetry of White Matter Pathways in Developing Human Brains.

    PubMed

    Song, Jae W; Mitchell, Paul D; Kolasinski, James; Ellen Grant, P; Galaburda, Albert M; Takahashi, Emi

    2015-09-01

    Little is known about the emergence of structural asymmetry of white matter tracts during early brain development. We examined whether and when asymmetry in diffusion parameters of limbic and association white matter pathways emerged in humans in 23 brains ranging from 15 gestational weeks (GW) up to 3 years of age (11 ex vivo and 12 in vivo cases) using high-angular resolution diffusion imaging tractography. Age-related development of laterality was not observed in a limbic connectional pathway (cingulum bundle or fornix). Among the studied cortico-cortical association pathways (inferior longitudinal fasciculus [ILF], inferior fronto-occipital fasciculus, and arcuate fasciculus), only the ILF showed development of age-related laterality emerging as early as the second trimester. Comparisons of ages older and younger than 40 GW revealed a leftward asymmetry in the cingulum bundle volume and a rightward asymmetry in apparent diffusion coefficient and leftward asymmetry in fractional anisotropy in the ILF in ages older than 40 GW. These results suggest that morphometric asymmetry in cortical areas precedes the emergence of white matter pathway asymmetry. Future correlative studies will investigate whether such asymmetry is anatomically/genetically driven or associated with functional stimulation.

  16. Assessing change in the earth's land surface albedo with moderate resolution satellite imagery

    NASA Astrophysics Data System (ADS)

    Sun, Qingsong

    Land surface albedo describes the proportion of incident solar radiant flux that is reflected from the Earth's surface and therefore is a crucial parameter in modeling and monitoring attempts to capture the current climate, hydrological, and biogeochemical cycles and predict future scenarios. Due to the temporal variability and spatial heterogeneity of land surface albedo, remote sensing offers the only realistic method of monitoring albedo on a global scale. While the distribution of bright, highly reflective surfaces (clouds, snow, deserts) govern the vast majority of the fluctuation, variations in the intrinsic surface albedo due to natural and human disturbances such as urban development, fire, pests, harvesting, grazing, flooding, and erosion, as well as the natural seasonal rhythm of vegetation phenology, play a significant role as well. The development of times series of global snow-free and cloud-free albedo from remotely sensed observations over the past decade and a half offers a unique opportunity to monitor and assess the impact of these alterations to the Earth's land surface. By utilizing multiple satellite records from the MODerate-resolution Imaging Spectroradiometer (MODIS), the Multi-angle Imaging Spectroradiometer (MISR) and the Visible Infrared Imaging Radiometer Suite (VIIRS) instruments, and developing innovative spectral conversion coefficients and temporal gap-filling strategies, it has been possible to utilize the strengths of the various sensors to improve the spatial and temporal coverage of global land surface albedo retrievals. The availability of these products is particularly important in tropical regions where cloud cover obscures the forest for significant periods. In the Amazon, field ecologists have noted that some areas of the forest ecosystem respond rapidly with foliage growth at the beginning of the dry season, when sunlight can finally penetrate fully to the surface and have suggested this phenomenon can continue until

  17. Spatially Complete Global Surface Albedos Derived from Terra/MODIS Data

    NASA Technical Reports Server (NTRS)

    King, Michael D.; Moody, Eric G.; Platnick, Steven; Schaaf, Crystal B.

    2004-01-01

    Spectral land surface albedo is an important parameter for describing the radiative properties of the Earth. Accordingly it reflects the consequences of natural and human interactions, such as anthropogenic, meteorological, and phenological effects, on global and local climatological trends. Consequently, albedos are integral parts in a variety of research areas, such as general circulation models (GCMs), energy balance studies, modeling of land use and land use change, and biophysical, oceanographic, and meteorological studies. Recent production of land surface anisotropy, diffuse bihemispherical (white-sky) albedo and direct beam directional hemispherical (black-sky) albedo from observations acquired by the MODIS instruments aboard NASA s Terra and Aqua satellite platforms have provided researchers with unprecedented spatial, spectral, and temporal information on the land surface's radiative characteristics. Cloud cover, which cutails retrievals, and the presence of ephemeral and seasonal snow limit the snow-free data to approximately half the global land surfaces on an annual equal-angle basis. This precludes the MOD43B3 albedo products from being used in some remote sensing and ground-based applications, climate models, and global change research projects. An ecosystem-dependent temporal interpolation technique is described that has been developed to fill missing or seasonally snow-covered data in the official MOD43B3 albedo product. The method imposes pixel-level and local regional ecosystem-dependent phenological behavior onto retrieved pixel temporal data in such a way as to maintain pixel-level spatial and spectral detail and integrity. The phenological curves are derived from statistics based on the MODIS MOD12Q1 IGBP land cover classification product geolocated with the MOD43B3 data. The resulting snow-free value-added products provide the scientific community with spatially and temporally complete global white- and black-sky surface albedo maps and

  18. Fire disturbance effects on land surface albedo in Alaskan tundra

    NASA Astrophysics Data System (ADS)

    French, Nancy H. F.; Whitley, Matthew A.; Jenkins, Liza K.

    2016-03-01

    The study uses satellite Moderate Resolution Imaging Spectroradiometer albedo products (MCD43A3) to assess changes in albedo at two sites in the treeless tundra region of Alaska, both within the foothills region of the Brooks Range, the 2007 Anaktuvuk River Fire (ARF) and 2012 Kucher Creek Fire (KCF). Results are compared to each other and other studies to assess the magnitude of albedo change and the longevity of impact of fire on land surface albedo. In both sites there was a marked decrease of albedo in the year following the fire. In the ARF, albedo slowly increased until 4 years after the fire, when it returned to albedo values prior to the fire. For the year immediately after the fire, a threefold difference in the shortwave albedo decrease was found between the two sites. ARF showed a 45.3% decrease, while the KCF showed a 14.1% decrease in shortwave albedo, and albedo is more variable in the KCF site than ARF site 1 year after the fire. These differences are possibly the result of differences in burn severity of the two fires, wherein the ARF burned more completely with more contiguous patches of complete burn than KCF. The impact of fire on average growing season (April-September) surface shortwave forcing in the year following fire is estimated to be 13.24 ± 6.52 W m-2 at the ARF site, a forcing comparable to studies in other treeless ecosystems. Comparison to boreal studies and the implications to energy flux are discussed in the context of future increases in fire occurrence and severity in a warming climate.

  19. Relationship between cloud radiative forcing, cloud fraction and cloud albedo, and new surface-based approach for determining cloud albedo

    SciTech Connect

    Liu, Y.; Wu, W.; Jensen, M. P.; Toto, T.

    2011-07-21

    This paper focuses on three interconnected topics: (1) quantitative relationship between surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo; (2) surface-based approach for measuring cloud albedo; (3) multiscale (diurnal, annual and inter-annual) variations and covariations of surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo. An analytical expression is first derived to quantify the relationship between cloud radiative forcing, cloud fraction, and cloud albedo. The analytical expression is then used to deduce a new approach for inferring cloud albedo from concurrent surface-based measurements of downwelling surface shortwave radiation and cloud fraction. High-resolution decade-long data on cloud albedos are obtained by use of this surface-based approach over the US Department of Energy's Atmospheric Radiaton Measurement (ARM) Program at the Great Southern Plains (SGP) site. The surface-based cloud albedos are further compared against those derived from the coincident GOES satellite measurements. The three long-term (1997-2009) sets of hourly data on shortwave cloud radiative forcing, cloud fraction and cloud albedo collected over the SGP site are analyzed to explore the multiscale (diurnal, annual and inter-annual) variations and covariations. The analytical formulation is useful for diagnosing deficiencies of cloud-radiation parameterizations in climate models.

  20. Simultaneous Cartography of Aerosol Opacity and Surface Albedo of Titan by the Massive Inversion of the Cassini/VIMS Dataset

    NASA Astrophysics Data System (ADS)

    Rodriguez, S.; Maltagliati, L.; Sotin, C.; Rannou, P.; Cornet, T.; Hirtzig, M.; Appéré, T.; Solomonidou, A.; Le Mouelic, S.; Coustenis, A.; Brown, R. H.

    2015-12-01

    Mapping Titan's surface albedo is a necessary step to give reliable constraints on its composition. However, surface albedo maps of Titan, especially over large regions, are still very rare, the surface windows being strongly affected by atmospheric effects (absorption, scattering). A full radiative transfer model is an essential tool to remove these effects, but too time-consuming to treat systematically the ~40000 hyperspectral images VIMS acquired since the beginning of the mission. We developed a massive inversion of VIMS data based on lookup tables computed from a state-of-the-art radiative transfer model (Hirtzig et al. 2013), updated with new aerosol properties coming from our analysis of the Emission Phase Function observation acquired recently by VIMS. Once the physical properties of gases, aerosols and surface are fixed, the lookup tables are built for the remaining free parameters: the incidence, emergence and azimuth angles, given by navigation; and two products (the aerosol opacity and the surface albedo at all wavelengths). The lookup table grid was carefully selected after thorough testing. The data inversion on these pre-computed spectra (opportunely interpolated) is more than 1000 times faster than recalling the full radiative transfer at each minimization step. We present here the results from selected flybys. We invert mosaics composed by couples of flybys observing the same area at two different times. The composite albedo maps do not show significant discontinuities in any of the surface windows, suggesting a robust correction of the effects of the geometry (and thus the aerosols) on the observations. Maps of aerosol and albedo uncertainties are also provided, with the absolute error on the albedo being approximately between 1 and 3% (depending on the surface window considered). We are thus able to provide for the first time ever reliable surface albedo maps at pixel scale for the whole VIMS spectral range.

  1. Analyses of the Variability Asymmetry of Kepler AGNs

    NASA Astrophysics Data System (ADS)

    Chen, Xiao-Yang; Wang, Jun-Xian

    2015-05-01

    The high-quality light curves from the Kepler space telescope make it possible to analyze the optical variability of active galactic nuclei (AGNs) with unprecedented time resolution. Studying the asymmetry in variations could provide independent constraints on physical models for AGN variability. In this paper, we use Kepler observations of 19 sources to perform analyses of the variability asymmetry of AGNs. We apply smoothing correction to light curves to deduct their bias toward high-frequency variability asymmetry caused by long-term variations that have been poorly sampled due to the limited length of light curves. A parameter β based on structure functions is introduced to quantitively describe the asymmetry and its uncertainty is measured using extensive Monte Carlo simulations. Individual sources show no evidence of asymmetry at timescales of 1˜ 20 days and there is no general trend toward positive or negative asymmetry over the whole sample. Stacking the data from all 19 AGNs, we derive an averaged \\bar{β } of 0.00 ± 0.03 and -0.02 ± 0.04 over timescales of 1 ˜ 5 days and 5 ˜ 20 days, respectively, which are statistically consistent with zero. Quasars and Seyfert galaxies show similar asymmetry parameters. Our results indicate that short-term optical variations in AGNs are highly symmetric.

  2. Bessel Weighted Asymmetries

    SciTech Connect

    Avakian, Harut; Gamberg, Leonard; Rossi, Patrizia; Prokudin, Alexei

    2016-05-01

    We review the concept of Bessel weighted asymmetries for semi-inclusive deep inelastic scattering and focus on the cross section in Fourier space, conjugate to the outgoing hadron’s transverse momentum, where convolutions of transverse momentum dependent parton distribution functions and fragmentation functions become simple products. Individual asymmetric terms in the cross section can be projected out by means of a generalized set of weights involving Bessel functions. The procedure is applied to studies of the double longitudinal spin asymmetry in semi-inclusive deep inelastic scattering using a new dedicated Monte Carlo generator which includes quark intrinsic transverse momentum within the generalized parton model. We observe a few percent systematic offset of the Bessel-weighted asymmetry obtained from Monte Carlo extraction compared to input model calculations, which is due to the limitations imposed by the energy and momentum conservation at the given energy and hard scale Q2. We find that the Bessel weighting technique provides a powerful and reliable tool to study the Fourier transform of TMDs with controlled systematics due to experimental acceptances and resolutions with different TMD model inputs.

  3. Asymmetry-driven structure formation in pair plasmas

    SciTech Connect

    Mahajan, S. M.; Shatashvili, N. L.; Berezhiani, V. I.

    2009-12-15

    The nonlinear propagation of electromagnetic waves in pair plasmas, in which the electrostatic potential plays a very important but subdominant role of a 'binding glue' is investigated. Several mechanisms for structure formation are investigated, in particular, the 'asymmetry' in the initial temperatures of the constituent species. It is shown that the temperature asymmetry leads to a (localizing) nonlinearity that is qualitatively different from the ones originating in ambient mass or density difference. The temperature-asymmetry-driven focusing-defocusing nonlinearity supports stable localized wave structures in 1-3 dimensions, which, for certain parameters, may have flat-top shapes.

  4. ALBEDOS OF SMALL HILDA GROUP ASTEROIDS AS REVEALED BY SPITZER

    SciTech Connect

    Ryan, Erin Lee; Woodward, Charles E. E-mail: chelsea@astro.umn.edu

    2011-06-15

    We present thermal 24 {mu}m observations from the Spitzer Space Telescope of 62 Hilda asteroid group members with diameters ranging from 3 to 12 km. Measurements of the thermal emission, when combined with reported absolute magnitudes, allow us to constrain the albedo and diameter of each object. From our Spitzer sample, we find the mean geometric albedo, p{sub V} = 0.07 {+-} 0.05, for small (D < 10 km) Hilda group asteroids. This Spitzer-derived value of p{sub V} is greater than and spans a larger range in albedo space than the mean albedo of large (D {approx}> 10 km) Hilda group asteroids which is p{sub V} = 0.04 {+-} 0.01. Though this difference may be attributed to space weathering, the small Hilda group population reportedly displays greater taxonomic range from C-, D-, and X-type whose albedo distributions are commensurate with the range of determined albedos. We discuss the derived Hilda size-frequency distribution, color-color space, and geometric albedo for our survey sample in the context of the expected migration induced 'seeding' of the Hilda asteroid group with outer solar system proto-planetesimals as outlined in the 'Nice' formalism.

  5. The Gamma-ray Albedo of the Moon

    SciTech Connect

    Moskalenko, Igor V.; Porter, Troy A.; /UC, Santa Cruz

    2007-09-28

    We use the GEANT4 Monte Carlo framework to calculate the {gamma}-ray albedo of the Moon due to interactions of cosmic ray (CR) nuclei with moon rock. Our calculation of the albedo spectrum agrees with the EGRET data. We show that the spectrum of {gamma}-rays from the Moon is very steep with an effective cutoff around 3-4 GeV (600 MeV for the inner part of the Moon disk) and exhibits a narrow pion-decay line at 67.5 MeV, perhaps unique in astrophysics. Apart from other astrophysical sources, the albedo spectrum of the Moon is well understood, including its absolute normalization; this makes it a useful 'standard candle' for {gamma}-ray telescopes. The steep albedo spectrum also provides a unique opportunity for energy calibration of {gamma}-ray telescopes, such as the forthcoming Gamma Ray Large Area Space Telescope (GLAST). Since the albedo flux depends on the incident CR spectrum which changes over the solar cycle, it is possible to monitor the CR spectrum using the albedo {gamma}-ray flux. Simultaneous measurements of CR proton and helium spectra by the Payload for Antimatter-Matter Exploration and Light-nuclei Astrophysics (PAMELA), and observations of the albedo {gamma}-rays by the GLAST Large Area Telescope (LAT), can be used to test the model predictions and will enable the LAT to monitor the CR spectrum near the Earth beyond the lifetime of the PAMELA.

  6. The Gamma-Ray Albedo of the Moon

    SciTech Connect

    Moskalenko, I.V.; Porter, T.A.; /UC, Santa Cruz

    2008-03-25

    We use the GEANT4 Monte Carlo framework to calculate the {gamma}-ray albedo of the Moon due to interactions of cosmic ray (CR) nuclei with moon rock. Our calculation of the albedo spectrum agrees with the EGRET data. We show that the spectrum of {gamma}-rays from the Moon is very steep with an effective cutoff around 3-4 GeV (600 MeV for the inner part of the Moon disk) and exhibits a narrow pion-decay line at 67.5 MeV, perhaps unique in astrophysics. Apart from other astrophysical sources, the albedo spectrum of the Moon is well understood, including its absolute normalization; this makes it a useful 'standard candle' for {gamma}-ray telescopes. The steep albedo spectrum also provides a unique opportunity for energy calibration of {gamma}-ray telescopes, such as the forthcoming Gamma Ray Large Area Space Telescope (GLAST). Since the albedo flux depends on the incident CR spectrum which changes over the solar cycle, it is possible to monitor the CR spectrum using the albedo {gamma}-ray flux. Simultaneous measurements of CR proton and helium spectra by the Payload for Antimatter-Matter Exploration and Light-nuclei Astrophysics (PAMELA), and observations of the albedo {gamma}-rays by the GLAST Large Area Telescope (LAT), can be used to test the model predictions and will enable the LAT to monitor the CR spectrum near the Earth beyond the lifetime of the PAMELA.

  7. Arid land monitoring using Landsat albedo difference images

    USGS Publications Warehouse

    Robinove, Charles J.; Chavez, Pat S.; Gehring, Dale G.; Holmgren, Ralph

    1981-01-01

    The Landsat albedo, or percentage of incoming radiation reflected from the ground in the wavelength range of 0.5 [mu]m to 1.1 [mu]m, is calculated from an equation using the Landsat digital brightness values and solar irradiance values, and correcting for atmospheric scattering, multispectral scanner calibration, and sun angle. The albedo calculated for each pixel is used to create an albedo image, whose grey scale is proportional to the albedo. Differencing sequential registered images and mapping selected values of the difference is used to create quantitative maps of increased or decreased albedo values of the terrain. All maps and other output products are in black and white rather than color, thus making the method quite economical. Decreases of albedo in arid regions may indicate improvement of land quality; increases may indicate degradation. Tests of the albedo difference mapping method in the Desert Experimental Range in southwestern Utah (a cold desert with little long-term terrain change) for a four-year period show that mapped changes can be correlated with erosion from flash floods, increased or decreased soil moisture, and increases or decreases in the density of desert vegetation, both perennial shrubs and annual plants. All terrain changes identified in this test were related to variations in precipitation. Although further tests of this method in hot deserts showing severe "desertification" are needed, the method is nevertheless recommended for experimental use in monitoring terrain change in other arid and semiarid regions of the world.

  8. Simulations of tropical rainforest albedo: is canopy wetness important?

    PubMed

    Yanagi, Silvia N M; Costa, Marcos H

    2011-12-01

    Accurate information on surface albedo is essential for climate modelling, especially for regions such as Amazonia, where the response of the regional atmospheric circulation to the changes on surface albedo is strong. Previous studies have indicated that models are still unable to correctly reproduce details of the seasonal variation of surface albedo. Therefore, it was investigated the role of canopy wetness on the simulated albedo of a tropical rainforest by modifying the IBIS canopy radiation transfer code to incorporate the effects of canopy wetness on the vegetation reflectance. In this study, simulations were run using three versions of the land surface/ecosystem model IBIS: the standard version, the same version recalibrated to fit the data of albedo on tropical rainforests and a modified version that incorporates the effects of canopy wetness on surface albedo, for three sites in the Amazon forest at hourly and monthly scales. The results demonstrated that, at the hourly time scale, the incorporation of canopy wetness on the calculations of radiative transfer substantially improves the simulations results, whereas at the monthly scale these changes do not substantially modify the simulated albedo.

  9. Characterization of the High-Albedo NEA 3691 Bede

    NASA Technical Reports Server (NTRS)

    Wooden, Diane H.; Lederer, Susan M.; Jehin, Emmanuel; Rozitis, Benjamin; Jefferson, Jeffrey D.; Nelson, Tyler W.; Dotson, Jessie L.; Ryan, Erin L.; Howell, Ellen S.; Fernandez, Yanga R.; Lovell, Amy J.; Woodward, Charles E.; Harker, David E.

    2016-01-01

    Characterization of NEAs provides important inputs to models for atmospheric entry, risk assessment and mitigation. Diameter is a key parameter because diameter translates to kinetic energy in atmospheric entry. Diameters can be derived from the absolute magnitude, H(PA=0deg), and from thermal modeling of observed IR fluxes. For both methods, the albedo (pv) is important - high pv surfaces have cooler temperatures, larger diameters for a given Hmag, and shallower phase curves (larger slope parameter G). Thermal model parameters are coupled, however, so that a higher thermal inertia also results in a cooler surface temperature. Multiple parameters contribute to constraining the diameter. Observations made at multiple observing geometries can contribute to understanding the relationships between and potentially breaking some of the degeneracies between parameters. We present data and analyses on NEA 3691 Bede with the aim of best constraining the diameter and pv from a combination of thermal modeling and light curve analyses. We employ our UKIRT+Michelle mid-IR photometric observations of 3691 Bede's thermal emission at 2 phase angles (27&43 deg 2015-03-19 & 04-13), in addition to WISE data (33deg 2010-05-27, Mainzer+2011). Observing geometries differ by solar phase angles and by moderate changes in heliocentric distance (e.g., further distances produce somewhat cooler surface temperatures). With the NEATM model and for a constant IR beaming parameter (eta=constant), there is a family of solutions for (diameter, pv, G, eta) where G is the slope parameter from the H-G Relation. NEATM models employing Pravec+2012's choice of G=0.43, produce D=1.8 km and pv˜0.4, given that G=0.43 is assumed from studies of main belt asteroids (Warner+2009). We present an analysis of the light curve of 3691 Bede to constrain G from observations. We also investigate fitting thermophysical models (TPM, Rozitis+11) to constrain the coupled parameters of thermal inertia (Gamma) and surface

  10. Sensitivity of the Weather Research and Forecast/Community Multiscale Air Quality modeling system to MODIS LAI, FPAR, and albedo

    NASA Astrophysics Data System (ADS)

    Ran, Limei; Gilliam, Robert; Binkowski, Francis S.; Xiu, Aijun; Pleim, Jonathan; Band, Larry

    2015-08-01

    This study aims to improve land surface processes in a retrospective meteorology and air quality modeling system through the use of Moderate Resolution Imaging Spectroradiometer (MODIS) vegetation and albedo products for more realistic vegetation and surface representation. MODIS leaf area index (LAI), fraction of absorbed photosynthetically active radiation (FPAR), and albedo are incorporated into the Pleim-Xiu land surface model (PX LSM) used in a combined meteorology and air quality modeling system. The current PX LSM intentionally exaggerates vegetation coverage and LAI in western dry lands so that its soil moisture nudging scheme is more effective in simulating surface temperature and mixing ratio. Reduced vegetation coverage from the PX LSM with MODIS input results in hotter and dryer daytime conditions with reduced ozone dry deposition velocities in much of western North America. Evaluations of the new system indicate greater error and bias in temperature, but reduced error and bias in moisture with the MODIS vegetation input. Hotter daytime temperatures and reduced dry deposition result in greater ozone concentrations in the western arid regions even with deeper boundary layer depths. MODIS albedo has much less impact on the meteorology simulations than MODIS LAI and FPAR. The MODIS vegetation and albedo input does not have much influence in the east where differences in vegetation and albedo parameters are less extreme. Evaluation results showing increased temperature errors with more accurate representation of vegetation suggests that improvements are needed in the model surface physics, particularly the soil processes in the PX LSM.

  11. Coherent Backscattering in Los Albedo Media

    NASA Astrophysics Data System (ADS)

    Nelson, R. M.; Hapke, B. W.; Hale, A. S.; Smythe, W. D.; Piatek, J.

    2002-09-01

    The opposition effect [1] observed in phase curves of materials in the lab and on planetary surfaces is attributed to two processes: 'shadow hiding opposition effect' (SHOE) and 'coherent backscattering opposition effect' (CBOE) [2,3,4]. The relative contributions of SHOE and CBOE are studied by measuring reflectance phase curves in circularly polarized light. If single scattering predominates, the circular polarization ratio (CPR) decreases with decreasing phase angle. If multiple scattering predominates, the CPR strongly increases. We observed this increase in CPR in highly reflective media [5,6,7]. In low reflectance media most of the returned signal is singly scattered and CPR is not expected to sharply increase. We have found that most such materials indeed exhibit only a slight CPR increase. However, lunar soils show a strong CPR increase [8]. Recently we encountered another interesting counter example in Boron Carbide-a material with albedo even lower than the Moon's. We find a significant CPR increase, a result inconsistent with the conventional interpretation of CBOE [8]. This suggests that albedo alone is not the principal regulator of CBOE. This CBOE may be due to multiple scattering within individual particles [10]. Unusual particle shapes may facilitate this process. Understanding this behavior contributes to the development of models that can retrieve textural properties from remote sensing data. Work performed at JPL/PITT under NASA PG&G grants. 1.Geherels, T. Astrophys. J, 123, 331-338, 1956. 2. Hapke, B. Icarus, 67, 246-280, 1986. 3. Shkuratov, Yu. SA-A.J., 27, 581-583, 1983. 4. Hapke, B. Icarus, 88, 407-417, 1990. 5. Nelson, R., et al. Icarus 131, 223-230, 1998. 6. Nelson, R., et al Icarus, 147, 545-558, 2000. 7. Nelson, R., et al. Planet. Space Sci, 2002. 8. Hapke B. et al. Science, 260, 509-511. 9. Mishchenko, M.I. Earth, Moon and Planets, 58, 127-144, 1992. 10. Hapke, B. Icarus, 157, 534-537, 2002

  12. North Atlantic Aerosol Single Scattering Albedos: TARFOX and ACE-2 Results and Their Relation to Radiative Effects Derived from Satellite Optical Depths

    NASA Technical Reports Server (NTRS)

    Russell, P. B.; Bergstrom, R. W.; Schmid, B.; Livingston, J. M.; Redemann, J.; Quinn, P. K.; Carrico, C. M.; Rood, M. J.

    2000-01-01

    Bergstrom and Russell estimated direct solar radiative flux changes caused by atmospheric aerosols over the mid-latitude North Atlantic Ocean under cloud-free and cloudy conditions. They excluded African dust aerosols, primarily by restricting calculations to latitudes 25-60 N. As inputs they used midvisible aerosol optical depth (AOD) maps derived from AVHRR satellite measurements and aerosol intensive properties determined primarily in the 1996 IGAC Troposheric Aerosol Radiative Forcing Observational Experiment (TARFOX). Those aerosol intensive properties, which included optical depth wavelength dependence and spectra of single scattering albedo (SSA) and scattering asymmetry parameter, were also checked against initial properties from the 1997 North Atlantic Aerosol Characterization Experiment (ACE 2). Bergstrom and Russell investigated the sensitivity of their derived flux changes to assumed input parameters, including midvisible AOD, SSA, and scattering asymmetry parameter. Although the sensitivity of net flux change at the tropopause to SSA was moderate over the ocean (e.g., a SSA uncertainty of 0.07 produced a flux-change uncertainty of 21%), the sensitivity over common land surfaces can be much larger. Also, flux changes within and below the aerosol layer, which affect atmospheric stability, heating rates, and cloud formation and persistence, are quite sensitive to aerosol SSA. Therefore, this paper focuses on the question: "What have we learned from TARFOX and ACE 2 regarding aerosol single scattering albedo?" Three techniques were used in TARFOX to determine midvisible SSA. One of these derived SSA as a best-fit parameter in comparing radiative flux changes measured by airborne pyranometer to those computed from aerosol properties. Another technique combined airborne measurements of aerosol scattering and absorption by nephelometer and absorption photometer. A third technique obtained SSA from best-fit complex refractive indices derived by comparing

  13. Earth albedo neutrons from 10 to 100 MeV.

    NASA Technical Reports Server (NTRS)

    Preszler, A. M.; Simnett, G. M.; White, R. S.

    1972-01-01

    We report the measurement of the energy and angular distributions of earth albedo neutrons from 10 to 100 MeV at 40 deg N geomagnetic latitude from a balloon at 120,000 ft, below 4.65 g/sq cm. The albedo-neutron omnidirectional energy distribution is flat to 50 MeV, then decreases with energy. The absolute neutron energy distribution is of the correct strength and shape for the albedo neutrons to be the source of the protons trapped in earth's inner radiation belt.

  14. The effect of aerosols on the earth-atmosphere albedo

    NASA Technical Reports Server (NTRS)

    Herman, B. M.; Browning, S. R.

    1975-01-01

    The paper presents calculations of the change in reflected flux by the earth-atmosphere system in response to increases in the atmospheric aerosol loading for a range of complex indices of refraction, solar elevation angle and ground albedo. Results show that, for small values of ground albedo, the reflected solar flux may either increase or decrease with increasing aerosol loadings, depending upon the complex part of the index of refraction of the aerosols. For high ground albedos, an increase in aerosol levels always results in a decrease of reflected flux (i.e., a warming of the earth-atmosphere system).

  15. Neutron dosimetry with TL albedo dosemeters at high energy accelerators.

    PubMed

    Haninger, T; Fehrenbacher, G

    2007-01-01

    The GSF-Personal Monitoring Service uses the TLD albedo dosemeter as standard neutron personal dosemeter. Due to its low sensitivity for fast neutrons however, it is generally not recommended for workplaces at high-energy accelerators. Test measurements with the albedo dosemeter were performed at the accelerator laboratories of GSI in Darmstadt and DESY in Hamburg to reconsider this hypothesis. It revealed that the albedo dosemeter can also be used as personal dosemeter at these workplaces, because at all measurement locations a significant part of neutrons with lower energies could be found, which were produced by scattering at walls or the ground.

  16. Lunar Terrain and Albedo Reconstruction from Apollo Imagery

    NASA Technical Reports Server (NTRS)

    Nefian, Ara V.; Kim, Taemin; Broxton, Michael; Moratto, Zach

    2010-01-01

    Generating accurate three dimensional planetary models and albedo maps is becoming increasingly more important as NASA plans more robotics missions to the Moon in the coming years. This paper describes a novel approach for separation of topography and albedo maps from orbital Lunar images. Our method uses an optimal Bayesian correlator to refine the stereo disparity map and generate a set of accurate digital elevation models (DEM). The albedo maps are obtained using a multi-image formation model that relies on the derived DEMs and the Lunar- Lambert reflectance model. The method is demonstrated on a set of high resolution scanned images from the Apollo era missions.

  17. Variable control of neutron albedo in toroidal fusion devices

    DOEpatents

    Jassby, Daniel L.; Micklich, Bradley J.

    1986-01-01

    An arrangement is provided for controlling neutron albedo in toroidal fusion devices having inboard and outboard vacuum vessel walls for containment of the neutrons of a fusion plasma. Neutron albedo material is disposed immediately adjacent the inboard wall, and is movable, preferably in vertical directions, so as to be brought into and out of neutron modifying communication with the fusion neutrons. Neutron albedo material preferably comprises a liquid form, but may also take pebble, stringer and curtain-like forms. A neutron flux valve, rotatable about a vertical axis is also disclosed.

  18. Aerial albedos of natural vegetation in South-eastern Australia

    NASA Technical Reports Server (NTRS)

    Howard, J. A.

    1977-01-01

    Black-and-white low-level 70mm photography was used to record the track of the aircraft, which was then plotted on conventional 1:80,000 23 cm photogrammetric photographs and referenced against simultaneous measurements of the beam albedos of vegetation. Using stereoscopic pairs of the 70mm photographs, the vegetation was classified into sub-formations. Marked differences in the 'sub-formation' albedos were observed. A two-way table using stand height and crown cover of the sub-formations clearly showed a very distinctive trend of albedos. This finding may be important in other vegetal studies.

  19. Facial asymmetry: a current review

    PubMed Central

    Thiesen, Guilherme; Gribel, Bruno Frazão; Freitas, Maria Perpétua Mota

    2015-01-01

    Abstract The term "asymmetry" is used to make reference to dissimilarity between homologous elements, altering the balance between structures. Facial asymmetry is common in the overall population and is often presented subclinically. Nevertheless, on occasion, significant facial asymmetry results not only in functional, but also esthetic issues. Under these conditions, its etiology should be carefully investigated in order to achieve an adequate treatment plan. Facial asymmetry assessment comprises patient's first interview, extra- as well as intraoral clinical examination, and supplementary imaging examination. Subsequent asymmetry treatment depends on patient's age, the etiology of the condition and on the degree of disharmony, and might include from asymmetrical orthodontic mechanics to orthognathic surgery. Thus, the present study aims at addressing important aspects to be considered by the orthodontist reaching an accurate diagnosis and treatment plan of facial asymmetry, in addition to reporting treatment of some patients carriers of such challenging disharmony. PMID:26691977

  20. Asymmetry in the Strong-field Photodetachment of H- by Linearly Polarized Few-cycle Pulses

    NASA Astrophysics Data System (ADS)

    Bai, Li-hua; Liu, Yu-heng; Cui, Ting-ting; Wang, Yan; Zhang, Hui-fang

    2011-04-01

    Photodetachment of H- irradiated by linearly polarized few-cycle laser field is investigated by time-dependent Schrödinger equation numerically. The photo-electron left-right asymmetry parameter as a function of carrier-envelop (CE) phase of few-cycle pulses is attained. We confirm the asymmetry of photoelectron distribution in H- photodetachment and find that the maximal asymmetry parameter of H- is equal to that of H atom under the same conditions but the corresponding CE phases are quite different. Thus a CE phase shift appears. Compared to that of H atom and field free electron, the zero asymmetry CE phase shift is sensitively affected by Coulomb field. The Coulomb effect on the asymmetry of H- photodetachment mainly behaves in the CE phase shift of H- instead of the amplitude of asymmetry parameter curve.

  1. White matter microstructure asymmetry: effects of volume asymmetry on fractional anisotropy asymmetry.

    PubMed

    Takao, H; Hayashi, N; Ohtomo, K

    2013-02-12

    Diffusion tensor imaging (DTI) provides information regarding white matter microstructure; however, macroscopic fiber architectures can affect DTI measures. A larger brain (fiber tract) has a 'relatively' smaller voxel size, and the voxels are less likely to contain more than one fiber orientation and more likely to have higher fractional anisotropy (FA). Previous DTI studies report left-to-right differences in the white matter; however, these may reflect true microscopic differences or be caused purely by volume differences. Using tract-based spatial statistics, we investigated left-to-right differences in white matter microstructure across the whole brain. Voxel-wise analysis revealed a large number of white matter volume asymmetries, including leftward asymmetry of the arcuate fasciculus and cingulum. In many white matter regions, FA asymmetry was positively correlated with volume asymmetry. Voxel-wise analysis with adjustment for volume asymmetry revealed many white matter FA asymmetries, including leftward asymmetry of the arcuate fasciculus and cingulum. The voxel-wise analysis showed a reduced number of regions with significant FA asymmetry compared with analysis performed without adjustment for volume asymmetry; however, the overall trend of the results was unchanged. The results of the present study suggest that these FA asymmetries are not caused by volume differences and reflect microscopic differences in the white matter.

  2. The sizes, albedos, and comae of Centaurs

    NASA Astrophysics Data System (ADS)

    Trilling, David; Mueller, Michael; Noll, Keith; Stansberry, John

    2008-03-01

    The small bodies of the Solar System retain the best information about the era of planet formation and the subsequent evolution of our planetary system. As escaped KBOs that wander close(r) to Earth and to the Sun, we have the opportunity to study KBOs with a sensitivity and resolution that is not generally available in the main Kuiper Belt. Centaurs are both dynamically transitional --- as former Kuiper Belt Objects and potentially future comets --- and physically so, as some display cometary activity that is absent in the Kuiper Belt. We propose here to observe 27 Centaurs with Spitzer to address these fundamental questions about this interesting transitional population. We will determine their physical properties --- size and albedo --- as a probe of their fundamental nature. We will carry out a coma search. This program will more than double the number of Centaurs observed with Spitzer and create a sample of nearly 50 targets in which we can look for correlations among physical properties and derive a true size distribution for Centaurs that can be compared to the best-known KBO and Jupiter family comet size distributions. If any Centaurs in our sample are observed to be binaries in a companion HST program, we will derive their densities, and compare Centaur densities to KBO densities. We will look for common properties among active Centaurs. The results will reveal the physical properties of this interesting transitional population, and help constrain the suggested link between Kuiper Belt Objects and Jupiter family comets.

  3. Position sense asymmetry.

    PubMed

    Adamo, Diane E; Martin, Bernard J

    2009-01-01

    Asymmetries in upper limb position sense have been explained in the context of a left limb advantage derived from differences in hemispheric specialization in the processing of kinesthetic information. However, it is not clearly understood how the comparison of perceptual information associated with passive limb displacement and the corresponding matching movement resulting from the execution of a motor command contributes to these differences. In the present study, upper limb position sense was investigated in 12 right-hand-dominant young adults performing wrist position matching tasks which varied in terms of interhemispheric transfer, memory retrieval and whether the reference position was provided by the same or opposite limb. Right and left hand absolute matching errors were similar when the reference and matching positions were produced by the same hand but were 36% greater when matching the reference position with the opposite hand. When examining the constant errors generated from matching movements made with the same hand that provided the reference, the right and left hand matching errors (approximately 3 degrees) were similar. However, when matching with the opposite limb, a large overshoot (P < 0.05) characterized the error when the right hand matched the left hand reference while a large undershoot (P < 0.05) characterized the error when the left hand matched the right hand reference. The overshoot and undershoot were of similar magnitude (approximately 4 degrees). Although asymmetries in the central processing of proprioceptive information such as interhemispheric transfer may exist, the present study suggests that asymmetries in position sense predominantly result from a difference in the "gain of the respective proprioceptive sensory-motor loops". This new hypothesis is strongly supported by a dual-linear model representing the right and left hand sensory-motor systems as well as morphological and physiological data.

  4. Mass predicts web asymmetry in Nephila spiders

    NASA Astrophysics Data System (ADS)

    Kuntner, Matjaž; Gregorič, Matjaž; Li, Daiqin

    2010-12-01

    The architecture of vertical aerial orb webs may be affected by spider size and gravity or by the available web space, in addition to phylogenetic and/or developmental factors. Vertical orb web asymmetry measured by hub displacement has been shown to increase in bigger and heavier spiders; however, previous studies have mostly focused on adult and subadult spiders or on several size classes with measured size parameters but no mass. Both estimations are suboptimal because (1) adult orb web spiders may not invest heavily in optimal web construction, whereas juveniles do; (2) size class/developmental stage is difficult to estimate in the field and is thus subjective, and (3) mass scales differently to size and is therefore more important in predicting aerial foraging success due to gravity. We studied vertical web asymmetry in a giant orb web spider, Nephila pilipes, across a wide range of size classes/developmental stages and tested the hypothesis that vertical web asymmetry (measured as hub displacement) is affected by gravity. On a sample of 100 webs, we found that hubs were more displaced in heavier and larger juveniles and that spider mass explained vertical web asymmetry better than other measures of spider size (carapace and leg lengths, developmental stage). Quantifying web shape via the ladder index suggested that, unlike in other nephilid taxa, growing Nephila orbs do not become vertically elongated. We conclude that the ontogenetic pattern of progressive vertical web asymmetry in Nephila can be explained by optimal foraging due to gravity, to which the opposing selective force may be high web-building costs in the lower orb. Recent literature finds little support for alternative explanations of ontogenetic orb web allometry such as the size limitation hypothesis and the biogenetic law.

  5. Mass predicts web asymmetry in Nephila spiders.

    PubMed

    Kuntner, Matjaz; Gregoric, Matjaz; Li, Daiqin

    2010-12-01

    The architecture of vertical aerial orb webs may be affected by spider size and gravity or by the available web space, in addition to phylogenetic and/or developmental factors. Vertical orb web asymmetry measured by hub displacement has been shown to increase in bigger and heavier spiders; however, previous studies have mostly focused on adult and subadult spiders or on several size classes with measured size parameters but no mass. Both estimations are suboptimal because (1) adult orb web spiders may not invest heavily in optimal web construction, whereas juveniles do; (2) size class/developmental stage is difficult to estimate in the field and is thus subjective, and (3) mass scales differently to size and is therefore more important in predicting aerial foraging success due to gravity. We studied vertical web asymmetry in a giant orb web spider, Nephila pilipes, across a wide range of size classes/developmental stages and tested the hypothesis that vertical web asymmetry (measured as hub displacement) is affected by gravity. On a sample of 100 webs, we found that hubs were more displaced in heavier and larger juveniles and that spider mass explained vertical web asymmetry better than other measures of spider size (carapace and leg lengths, developmental stage). Quantifying web shape via the ladder index suggested that, unlike in other nephilid taxa, growing Nephila orbs do not become vertically elongated. We conclude that the ontogenetic pattern of progressive vertical web asymmetry in Nephila can be explained by optimal foraging due to gravity, to which the opposing selective force may be high web-building costs in the lower orb. Recent literature finds little support for alternative explanations of ontogenetic orb web allometry such as the size limitation hypothesis and the biogenetic law.

  6. Rubber friction directional asymmetry

    NASA Astrophysics Data System (ADS)

    Tiwari, A.; Dorogin, L.; Steenwyk, B.; Warhadpande, A.; Motamedi, M.; Fortunato, G.; Ciaravola, V.; Persson, B. N. J.

    2016-12-01

    In rubber friction studies it is usually assumed that the friction force does not depend on the sliding direction, unless the substrate has anisotropic properties, like a steel surface grinded in one direction. Here we will present experimental results for rubber friction, where we observe a strong asymmetry between forward and backward sliding, where forward and backward refer to the run-in direction of the rubber block. The observed effect could be very important in tire applications, where directional properties of the rubber friction could be induced during braking.

  7. Simultaneous Retrieval of Multiple Aerosol Parameters Using a Multi-Angular Approach

    NASA Technical Reports Server (NTRS)

    Kuo, K. S.; Weger, R. C.; Welch, R. M.

    1997-01-01

    Atmospheric aerosol particles, both natural and anthropogenic, are important to the earth's radiative balance through their direct and indirect effects. They scatter the incoming solar radiation (direct effect) and modify the shortwave reflective properties of clouds by acting as cloud condensation nuclei (indirect effect). Although it has been suggested that aerosols exert a net cooling influence on climate, this effect has received less attention than the radiative forcing due to clouds and greenhouse gases. In order to understand the role that aerosols play in a changing climate, detailed and accurate observations are a prerequisite. The retrieval of aerosol optical properties by satellite remote sensing has proven to be a difficult task. The difficulty results mainly from the tenuous nature and variable composition of aerosols. To date, with single-angle satellite observations, we can only retrieve reliably against dark backgrounds, such as over oceans and dense vegetation. Even then, assumptions must be made concerning the chemical composition of aerosols. The best hope we have for aerosol retrievals over bright backgrounds are observations from multiple angles, such as those provided by the MISR and POLDER instruments. In this investigation we examine the feasibility of simultaneous retrieval of multiple aerosol optical parameters using reflectances from a typical set of twelve angles observed by the French POLDER instrument. The retrieved aerosol optical parameters consist of asymmetry factor, single scattering albedo, surface albedo, and optical thickness.

  8. Simultaneous Retrieval of Multiple Aerosol Parameters Using a Multi-Angular Approach

    NASA Technical Reports Server (NTRS)

    Kuo, K.-S.; Weger, R. C.; Welch, R. M.

    1997-01-01

    Atmospheric aerosol particles, both natural and anthropogenic, are important to the earth's radiative balance through their direct and indirect effects. They scatter the incoming solar radiation (direct effect) and modify the shortwave reflective properties of clouds by acting as cloud condensation nuclei (indirect effect). Although it has been suggested that aerosols exert a net cooling influence on climate, this effect has received less attention than the radiative forcing due to clouds and greenhouse gases. In order to understand the role that aerosols play in a changing climate, detailed and accurate observations are a prerequisite. The retrieval of aerosol optical properties by satellite remote sensing has proven to be a difficult task. The difficulty results mainly from the tenuous nature and variable composition of aerosols. To date, with single-angle satellite observations, we can only retrieve reliably against dark backgrounds, such as over oceans and dense vegetation. Even then, assumptions must be made concerning the chemical composition of aerosols. In this investigation we examine the feasibility of simultaneous retrieval of multiple aerosol optical parameters using reflectances from a typical set of twelve angles observed by the French POLDER instrument. The retrieved aerosol optical parameters consist of asymmetry factor, single scattering albedo, surface albedo, and optical thickness.

  9. Use of a spherical albedo system for correcting the readings of albedo dosimeters in JINR phasotron neutron radiation fields

    NASA Astrophysics Data System (ADS)

    Mokrov, Yu. V.; Morozova, S. V.

    2014-03-01

    Results of calibrating a spherical albedo system in the radiation fields of a Pu-Be radionuclide neutron source are presented. It is shown that it can be used for correcting the readings of the DVGN-01 albedo dosimeter. The results of measurements with the system in JINR phasotron neutron fields for the purpose of correcting the DVGN-01 readings in these fields are given. The values of the correction factors for DVGN-01 albedo dosimeters when used in personnel neutron dosimetry (PD) on the JINR phasotron are determined.

  10. A simplified treatment of SiB's land surface albedo parameterization

    NASA Technical Reports Server (NTRS)

    Koster, Randal D.; Suarez, Max J.

    1991-01-01

    The earlier presented surface albedo parameterization is simplified by assuming that the reflectance of direct solar radiation is a simple function of solar zenith angle. The function chosen contains three parameters that vary with vegetation type, greenness, and leaf area index. Tables of parameter values are presented. Using these tables, SiB's (Simple Biosphere model) absorbances of direct solar radiation can be reproduced with an average relative error of less than 0.5 percent. Finally, the direct reflectance function is integrated over zenith angle to produce an equation for the surface reflectance of diffuse radiation.

  11. Albedo neutron dosimetry in Germany: regulations and performance.

    PubMed

    Luszik-Bhadra, M; Zimbal, A; Busch, F; Eichelberger, A; Engelhardt, J; Figel, M; Frasch, G; Günther, K; Jordan, M; Martini, E; Haninger, T; Rimpler, A; Seifert, R

    2014-12-01

    Personal neutron dosimetry has been performed in Germany using albedo dosemeters for >20 y. This paper describes the main principles, the national standards, regulations and recommendations, the quality management and the overall performance, giving some examples.

  12. Cloud condensation nucleus-sulfate mass relationship and cloud albedo

    NASA Technical Reports Server (NTRS)

    Hegg, Dean A.

    1994-01-01

    Analysis of previously published, simultaneous measurements of cloud condensation nucleus number concentration and sulfate mass concentration suggest a nonlinear relationship between the two variables. This nonlinearity reduces the sensitivity of cloud albedo to changes in the sulfur cycle.

  13. Albedo Pattern Recognition and Time-Series Analyses in Malaysia

    NASA Astrophysics Data System (ADS)

    Salleh, S. A.; Abd Latif, Z.; Mohd, W. M. N. Wan; Chan, A.

    2012-07-01

    Pattern recognition and time-series analyses will enable one to evaluate and generate predictions of specific phenomena. The albedo pattern and time-series analyses are very much useful especially in relation to climate condition monitoring. This study is conducted to seek for Malaysia albedo pattern changes. The pattern recognition and changes will be useful for variety of environmental and climate monitoring researches such as carbon budgeting and aerosol mapping. The 10 years (2000-2009) MODIS satellite images were used for the analyses and interpretation. These images were being processed using ERDAS Imagine remote sensing software, ArcGIS 9.3, the 6S code for atmospherical calibration and several MODIS tools (MRT, HDF2GIS, Albedo tools). There are several methods for time-series analyses were explored, this paper demonstrates trends and seasonal time-series analyses using converted HDF format MODIS MCD43A3 albedo land product. The results revealed significance changes of albedo percentages over the past 10 years and the pattern with regards to Malaysia's nebulosity index (NI) and aerosol optical depth (AOD). There is noticeable trend can be identified with regards to its maximum and minimum value of the albedo. The rise and fall of the line graph show a similar trend with regards to its daily observation. The different can be identified in term of the value or percentage of rises and falls of albedo. Thus, it can be concludes that the temporal behavior of land surface albedo in Malaysia have a uniform behaviours and effects with regards to the local monsoons. However, although the average albedo shows linear trend with nebulosity index, the pattern changes of albedo with respects to the nebulosity index indicates that there are external factors that implicates the albedo values, as the sky conditions and its diffusion plotted does not have uniform trend over the years, especially when the trend of 5 years interval is examined, 2000 shows high negative linear

  14. Global land surface albedo maps from MODIS using the Google Earth Engine

    NASA Astrophysics Data System (ADS)

    Mitraka, Zina; Benas, Nikolaos; Gorelick, Noel; Chrysoulakis, Nektarios

    2016-04-01

    The land surface albedo (LSA) is a critical physical variable, which influences the Earth's climate by affecting the energy budget and distribution in the Earth-atmosphere system. Its role is highly significant in both global and local scales; hence, LSA measurements provide a quantitative means for better constraining global and regional scale climate modelling efforts. The Moderate Resolution Imaging Spectroradiometer (MODIS) sensor, on board NASA's Terra and Aqua platforms, provides the parameters needed for the computation of LSA on an 8-day temporal scale and a variety of spatial scales (ranging between 0.5 - 5 km). This dataset was used here for the LSA estimation and its changes over the study area at 0.5 km spatial resolution. More specifically, the MODIS albedo product was used, which includes both the directional-hemispherical surface reflectance (black-sky albedo) and the bi-hemispherical surface reflectance (white-sky albedo). The LSA was estimated for the whole globe on an 8-day basis for the whole time period covered by MODIS acquisitions (i.e. 2000 until today). To estimate LSA from black-sky and white-sky albedos, the fraction of the diffused radiation is needed, a function of the Aerosol Optical Thickness (AOT). Required AOT information was acquired from the MODIS AOT product at 1̊ × 1̊ spatial resolution. Since LSA also depends on solar zenith angle (SZA), 8-day mean LSA values were computed as averages of corresponding LSA values for representative SZAs covering the 24-hour day. The estimated LSA was analysed in terms of both spatial and seasonal characteristics, while LSA changes during the period examined were assessed. All computation were performed using the Google Earth Engine (GEE). The GEE provided access to all the MODIS products needed for the analysis without the need of searching or downloading. Moreover, the combination of MODIS products in both temporal and spatial terms was fast and effecting using the GEE API (Application

  15. Improving modeled snow albedo estimates during the spring melt season

    NASA Astrophysics Data System (ADS)

    Malik, M. Jahanzeb; Velde, Rogier; Vekerdy, Zoltan; Su, Zhongbo

    2014-06-01

    Snow albedo influences snow-covered land energy and water budgets and is thus an important variable for energy and water fluxes calculations. Here, we quantify the performance of the three existing snow albedo parameterizations under alpine, tundra, and prairie snow conditions when implemented in the Noah land surface model (LSM)—Noah's default and ones from the Biosphere-Atmosphere Transfer Scheme (BATS) and the Canadian Land Surface Scheme (CLASS) LSMs. The Noah LSM is forced with and its output is evaluated using in situ measurements from seven sites in U.S. and France. Comparison of the snow albedo simulations with the in situ measurements reveals that the three parameterizations overestimate snow albedo during springtime. An alternative snow albedo parameterization is introduced that adopts the shape of the variogram for the optically thick snowpacks and decreases the albedo further for optically thin conditions by mixing the snow with the land surface (background) albedo as a function of snow depth. In comparison with the in situ measurements, the new parameterization improves albedo simulation of the alpine and tundra snowpacks and positively impacts the simulation of snow depth, snowmelt rate, and upward shortwave radiation. An improved model performance with the variogram-shaped parameterization can, however, not be unambiguously detected for prairie snowpacks, which may be attributed to uncertainties associated with the simulation of snow density. An assessment of the model performance for the Upper Colorado River Basin highlights that with the variogram-shaped parameterization Noah simulates more evapotranspiration and larger runoff peaks in Spring, whereas the Summer runoff is lower.

  16. Surface albedo observations at Gusev Crater and Meridiani Planum, Mars

    USGS Publications Warehouse

    Bell, J.F.; Rice, M.S.; Johnson, J. R.; Hare, T.M.

    2008-01-01

    During the Mars Exploration Rover mission, the Pancam instrument has periodically acquired large-scale panoramic images with its broadband (739??338 nm) filter in order to estimate the Lambert bolometric albedo of the surface along each rover's traverse. In this work we present the full suite of such estimated albedo values measured to date by the Spirit and Opportunity rovers along their traverses in Gusev Crater and Meridiani Planum, respectively. We include estimated bolometric albedo values of individual surface features (e.g., outcrops, dusty plains, aeolian bed forms, wheel tracks, light-toned soils, and crater walls) as well as overall surface averages of the 43 total panoramic albedo data sets acquired to date. We also present comparisons to estimated Lambert albedo values taken from the Mars Global Surveyor Mars Orbiter Camera (MOC) along the rovers' traverses, and to the large-scale bolometric albedos of the sites from the Viking Orbiter Infrared Thermal Mapper (IRTM) and Mars Global Surveyor/Thermal Emission Spectrometer (TES). The ranges of Pancam-derived albedos at Gusev Crater (0.14 to 0.25) and in Meridiani Planum. (0.10 to 0.18) are in good agreement with IRTM, TES, and MOC orbital measurements. These data sets will be a useful tool and benchmark for future investigations of albodo variations with time, including measurements from orbital instruments like the Context Camera and High Resolution Imaging Science Experiment on Mars Reconnaissance Orbiter. Long-term, accurate albedo measurements could also be important for future efforts in climate modeling as well as for studies of active surface processes. Copyright 2008 by the American Geophysical Union.

  17. IAU nomenclature for albedo features on the planet Mercury

    NASA Technical Reports Server (NTRS)

    Dollfus, A.; Chapman, C. R.; Davies, M. E.; Gingerich, O.; Goldstein, R.; Guest, J.; Morrison, D.; Smith, B. A.

    1978-01-01

    The International Astronomical Union has endorsed a nomenclature for the albedo features on Mercury. Designations are based upon the mythological names related to the god Hermes; they are expressed in Latin form. The dark-hued albedo features are associated with the generic term Solitudo. The light-hued areas are designated by a single name without generic term. The 32 names adopted are allocated on the Mercury map.

  18. Albedo as a modulator of climate response to tropical deforestation

    SciTech Connect

    Dirmeyer, P.A.; Shukla, J.

    1994-10-01

    An atmospheric general circulation model with land surface properties represented by the simplified Simple Biosphere model is used to investigate the effects on local climate due to tropical deforestation for the Amazon basin. One control and three anomaly integrations of 4 years` duration are performed. In the anomaly integrations, rain forest in South America is replaced by degraded grassland. The anomaly integrations differ only in the optical properties of the grassland vegetation, with net surface albedos ranging from the same as to 0.09 lighter than that of rain forest. It is found that the change in climate, particularly rainfall, is strongly dependent on the change in surface albedo that accompanies deforestation. Replacement of forest by grass causes a reduction in transpiration and reduces frictional convergence by decreasing surface roughness. However, precipitation averaged over the deforested area is not necessarily reduced. Average precipitation decreases when the increase in albedo is greater than 0.03. If surface albedo is not increased appreciably as a result of deforestation, moisture flux convergence driven by the increase in surface temperature can offset the other effects, and average precipitation increases. As albedo is increased, surface temperature does not change, but surface latent and sensible heat flux decreases due to reduced radiational energy absorbed at the surface, resulting in a reduction in convection and precipitation. A change in the distribution of precipitation due to deforestation that appears to be independent of the albedo is observed.

  19. Albedo as a modulator of climate response to tropical deforestation

    NASA Technical Reports Server (NTRS)

    Dirmeyer, Paul A.; Shukla, J.

    1994-01-01

    An atmospheric general circulation model with land surface properties represented by the simplified Simple Biosphere model is used to investigate the effects on local climate due to tropical deforestation for the Amazon basin. One control and three anomaly integrations of 4 years' duration are performed. In the anomaly integrations, rain forest in South America is replaced by degraded grassland. The anomaly integrations differ only in the optical properties of the grassland vegetation, with net surface albedos ranging from the same as to 0.09 lighter than that of rain forest. It is found that the change in climate, particularly rainfall, is strongly dependent on the change in surface albedo that accompanies deforestation. Replacement of forest by grass causes a reduction in transpiration and reduces frictional convergence by decreasing surface roughness. However, precipitation averaged over the deforested area is not necessarily reduced. Average precipitation decreases when the increase in albedo is greater than 0.03. If surface albedo is not increased appreciably as a result of deforestation, moisture flux convergence driven by the increase in surface temperature can offset the other effects, and average precipitation increases. As albedo is increased, surface temperature does not change, but surface latent and sensible heat flux decreases due to reduced radiational energy absorbed at the surface, resulting in a reduction in convection and precipitation. A change in the distribution of precipitation due to deforestation that appears to be independent of the albedo is observed.

  20. Accurate albedos of the brightest regions on Io

    NASA Astrophysics Data System (ADS)

    Simonelli, D. P.; Veverka, J.

    1985-04-01

    The brightest, coldest areas on Io, the white regions, may act as cold traps for SO2 gas, and thus have an important role in governing the pressure, diurnal variation, and flow of the satellite's tenuous SO2 atmosphere. Therefore, it is essential to derive accurate albedos for the brightest regions, where the necessary albedos are those in the energy balance equation of the surface used to compute temperatures. Forty-one of the brightest of the white areas, each 60 to 120 km on a side were studied. The simplest way to estimate the required energy balance albedo for each region is to determine the Bond slbedo of a planet covered with that type of material. This process is outlined and resulting albedos are given. with the exception of several darker regions on the poorly-resolved post eclipse face of Io, typical albedos are 0.6 to 0.7. The brightest areas studied are located in the cluster of white regions east of Prometheus (longitudes 90 to 40 deg W). It is possible using Voyager data and fits to Hapke's equation to derive albedos for the bright regions without making any assumptions about the phase integrals.

  1. Spectral albedo and transmittance of thin young Arctic sea ice

    NASA Astrophysics Data System (ADS)

    Taskjelle, Torbjørn; Hudson, Stephen R.; Granskog, Mats A.; Nicolaus, Marcel; Lei, Ruibo; Gerland, Sebastian; Stamnes, Jakob J.; Hamre, Børge

    2016-01-01

    Spectral albedo and transmittance in the range were measured on three separate dates on less than thick new Arctic sea ice growing on Kongsfjorden, Svalbard at , . Inherent optical properties, including absorption coefficients of particulate and dissolved material, were obtained from ice samples and fed into a radiative transfer model, which was used to analyze spectral albedo and transmittance and to study the influence of clouds and snow on these. Integrated albedo and transmittance for photosynthetically active radiation () were in the range 0.17-0.21 and 0.77-0.86, respectively. The average albedo and transmittance of the total solar radiation energy were 0.16 and 0.51, respectively. Values inferred from the model indicate that the ice contained possibly up to 40% brine and only 0.6% bubbles. Angular redistribution of solar radiation by clouds and snow was found to influence both the wavelength-integrated value and the spectral shape of albedo and transmittance. In particular, local peaks and depressions in the spectral albedo and spectral transmittance were found for wavelengths within atmospheric absorption bands. Simulated and measured transmittance spectra were within 5% for most of the wavelength range, but deviated up to 25% in the vicinity of , indicating the need for more optical laboratory measurements of pure ice, or improved modeling of brine optical properties in this near-infrared wavelength region.

  2. Simultaneous Spectral Albedo Measurements Near the Atmospheric Radiation Measurement Southern Great Plains (ARM SGP) Central Facility

    SciTech Connect

    Michalsky, Joseph J.; Min, Qilong; Barnard, James C.; Marchand, Roger T.; Pilewskie, Peter

    2003-04-30

    In this study, a data analysis is performed to determine the area-averaged, spectral albedo at ARM's SGP central facility site. The spectral albedo is then fed into radiation transfer models to show that the diffuse discrepancy is diminished when the spectral albedo is used (as opposed to using the broadband albedo).

  3. Lepton forward-backward asymmetries

    SciTech Connect

    Pain, R. ); DELPHI Collaboration,

    1992-02-01

    Results of Forward-Backward Asymmetries with Leptons measured at [ital Z][sup 0] energies are presented. Details of the analysis by the DELPHI Collaboration are given together with the most recent values of the peak Asymmetries for electrons, muons, and taus obtained by ALEPH, DELPHI, L3, and OPAL Collaborations at LEP.

  4. Lip asymmetry and smile aesthetics.

    PubMed

    Batwa, Waeil; McDonald, Fraser; Cash, Alex

    2013-11-01

    Objective : To determine if lip asymmetry can affect lip aesthetics. Setting and Participants : A group of dentists (n = 40) and cleft patients (n = 40) were recruited from the dental hospital and cleft service. Interventions : Still photographic digital images of lips and teeth were manipulated to produce a computerized gradient of smile appearance with different degrees of upper-lip vertical asymmetry. These five photographs (with 0 mm representing "symmetry," and 1, 2, 2.5, and 3 mm, asymmetries) were assessed by participants using a 5-point Likert scale. Statistics : Descriptive statistics in addition to chi-square test were used to analyze the data. In order to satisfy the requirement of the chi-square test, the five smile ratings were reduced to three. Results : Lip asymmetry did affect relative smile aesthetics, as determined by dentists and cleft patients. Both the dentists and cleft patients rated the 0-mm photograph more attractive than the 2.5-mm and 3-mm smiles (P < .05). The 0-, 1-, and 2-mm smiles were indistinguishable for both dentists and cleft patients. Conclusion : Lip asymmetry affects smile aesthetics. However, cleft patients and dentists were tolerant of minor asymmetries. This suggests that small degrees of lip asymmetry do not affect relative smile aesthetics as much as large degrees of lip asymmetry (2.5 mm or more).

  5. Electron energy and charge albedos - calorimetric measurement vs Monte Carlo theory

    SciTech Connect

    Lockwood, G.J.; Ruggles, L.E.; Miller, G.H.; Halbleib, J.A.

    1981-11-01

    A new calorimetric method has been employed to obtain saturated electron energy albedos for Be, C, Al, Ti, Mo, Ta, U, and UO/sub 2/ over the range of incident energies from 0.1 to 1.0 MeV. The technique was so designed to permit the simultaneous measurement of saturated charge albedos. In the cases of C, Al, Ta, and U the measurements were extended down to about 0.025 MeV. The angle of incidence was varied from 0/sup 0/ (normal) to 75/sup 0/ in steps of 15/sup 0/, with selected measurements at 82.5/sup 0/ in Be and C. In each case, state-of-the-art predictions were obtained from a Monte Carlo model. The generally good agreement between theory and experiment over this extensive parameter space represents a strong validation of both the theoretical model and the new experimental method. Nevertheless, certain discrepancies at low incident energies, especially in high-atomic-number materials, and at all energies in the case of the U energy albedos are not completely understood.

  6. Phase-Angle Dependence of Determinations of Diameter, Albedo, and Taxonomy: A Case Study of NEO 3691 Bede

    NASA Technical Reports Server (NTRS)

    Wooden, Diane H.; Lederer, Susan M.; Jehin, Emmanuel; Howell, Ellen S.; Fernandez, Yan; Harker, David E.; Ryan, Erin; Lovell, Amy; Woodward, Charles E.; Benner, Lance A.

    2015-01-01

    Parameters important for NEO risk assessment and mitigation include Near-Earth Object diameter and taxonomic classification, which translates to surface composition. Diameters of NEOs are derived from the thermal fluxes measured by WISE, NEOWISE, Spitzer Warm Mission and ground-based telescopes including the IRTF and UKIRT. Diameter and its coupled parameters Albedo and IR beaming parameter (a proxy for thermal inertia and/or surface roughness) are dependent upon the phase angle, which is the Sun-target-observer angle. Orbit geometries of NEOs, however, typically provide for observations at phase angles greater than 20 degrees. At higher phase angles, the observed thermal emission is sampling both the day and night sides of the NEO. We compare thermal models for NEOs that exclude (NEATM) and include (NESTM) night-side emission. We present a case study of NEO 3691 Bede, which is a higher albedo object, X (Ec) or Cgh taxonomy, to highlight the range of H magnitudes for this object (depending on the albedo and phase function slope parameter G), and to examine at different phase angles the taxonomy and thermal model fits for this NEO. Observations of 3691 Bede include our observations with IRTF+SpeX and with the 10 micrometer UKIRT+Michelle instrument, as well as WISE and Spitzer Warm mission data. By examining 3691 Bede as a case study, we highlight the interplay between the derivation of basic physical parameters and observing geometry, and we discuss the uncertainties in H magnitude, taxonomy assignment amongst the X-class (P, M, E), and diameter determinations. Systematic dependencies in the derivation of basic characterization parameters of H-magnitude, diameter, albedo and taxonomy with observing geometry are important to understand. These basic characterization parameters affect the statistical assessments of the NEO population, which in turn, affects the assignment of statistically-assessed basic parameters to discovered but yet-to-be-fully-characterized NEOs.

  7. Phase-Angle Dependence of Determinations of Diameter, Albedo, and Taxonomy: A case study of NEO 3691 Bede

    NASA Astrophysics Data System (ADS)

    Wooden, D. H.; Lederer, S. M.; Jehin, E.; Howell, E. S.; Fernandez, Y. R.; Harker, D. E.; Ryan, E. L.; Lovell, A. J.; Woodward, C. E.; Benner, L.

    2015-12-01

    Parameters important for NEO risk assessment and mitigation include Near-Earth Object diameter and taxonomic classification, which translates to surface composition. Diameters of NEOs are derived from the thermal fluxes measured by WISE, NEOWISE, Spitzer Warm Mission and ground-based telescopes including the IRTF and UKIRT. Diameter and its coupled parameters Albedo and IR beaming parameter (a proxy for thermal inertia and/or surface roughness) are dependent upon the phase angle, which is the Sun-target-observer angle. Orbit geometries of NEOs, however, typically provide for observations at phase angles > 20 degrees. At higher phase angles, the observed thermal emission is sampling both the day and night sides of the NEO. We compare thermal models for NEOs that exclude (NEATM) and include (NESTM) night-side emission. We present a case study of NEO 3691 Bede, which is a higher albedo object, X (Ec) or Cgh taxonomy, to highlight the range of H magnitudes for this object (depending on the albedo and phase function slope parameter G), and to examine at different phase angles the taxonomy and thermal model fits for this NEO. Observations of 3691 Bede include our observations with IRTF+SpeX and with the 10μm UKIRT+Michelle instrument, as well as WISE and Spitzer Warm mission data. By examining 3691 Bede as a case study, we highlight the interplay between the derivation of basic physical parameters and observing geometry, and we discuss the uncertainties in H magnitude, taxonomy assignment amongst the X-class (P, M, E), and diameter determinations. Systematic dependencies in the derivation of basic characterization parameters of H-magnitude, diameter, albedo and taxonomy with observing geometry are important to understand. These basic characterization parameters affect the statistical assessments of the NEO population, which in turn, affects the assignment of statistically-assessed basic parameters to discovered but yet-to-be-fully-characterized NEOs.

  8. Measurements of W Charge Asymmetry

    SciTech Connect

    Holzbauer, J. L.

    2015-10-06

    We discuss W boson and lepton charge asymmetry measurements from W decays in the electron channel, which were made using 9.7 fb$^{-1}$ of RunII data collected by the D0 detector at the Fermilab Tevatron Collider. The electron charge asymmetry is presented as a function of pseudo-rapidity out to |$\\eta$| $\\le$ 3.2, in five symmetric and asymmetric kinematic bins of electron transverse momentum and the missing transverse energy of the event. We also give the W charge asymmetry as a function of W boson rapidity. The asymmetries are compared with next-to-leading order perturbative quantum chromodynamics calculations. These charge asymmetry measurements will allow more accurate determinations of the proton parton distribution functions and are the most precise to date.

  9. Clear-Sky Narrowband Albedo Variations Derived from VIRS and MODIS Data

    NASA Technical Reports Server (NTRS)

    Sun-Mack, Sunny; Chen, Yan; Arduini, Robert F.; Minnis, Patrick

    2004-01-01

    A critical parameter for detecting clouds and aerosols and for retrieving their microphysical properties is the clear-sky radiance. The Clouds and the Earth's Radiant Energy System (CERES) Project uses the visible (VIS; 0.63 m) and near-infrared (NIR; 1.6 or 2.13 m) channels available on same satellites as the CERES scanners. Another channel often used for cloud and aerosol, and vegetation cover retrievals is the vegetation (VEG; 0.86- m) channel that has been available on the Advanced Very High Resolution Radiometer (AVHRR) for many years. Generally, clear-sky albedo for a given surface type is determined for conditions when the vegetation is either thriving or dormant and free of snow. Snow albedo is typically estimated without considering the underlying surface type. The albedo for a surface blanketed by snow, however, should vary with surface type because the vegetation often emerges from the snow to varying degrees depending on the vertical dimensions of the vegetation. For example, a snowcovered prairie will probably be brighter than a snowcovered forest because the snow typically falls off the trees exposing the darker surfaces while the snow on a grassland at the same temperatures will likely be continuous and, therefore, more reflective. Accounting for the vegetation-induced differences should improve the capabilities for distinguishing snow and clouds over different surface types and facilitate improvements in the accuracy of radiative transfer calculations between the snow-covered surface and the atmosphere, eventually leading to improvements in models of the energy budgets over land. This paper presents a more complete analysis of the CERES spectral clear-sky reflectances to determine the variations in clear-sky top-of-atmosphere (TOA) albedos for both snow-free and snow-covered surfaces for four spectral channels using data from Terra and Aqua.. The results should be valuable for improved cloud retrievals and for modeling radiation fields.

  10. Possibility for albedo estimation of exomoons: Why should we care about M dwarfs?

    NASA Astrophysics Data System (ADS)

    Dobos, Vera; Kereszturi, Ákos; Pál, András; Kiss, László L.

    2016-08-01

    Occultation light curves of exomoons may give information on the exomoons' albedo and hence indicate the presence of ice cover on the surface. Icy moons might have subsurface oceans, and thus may potentially be habitable. The objective of our paper is to determine whether next generation telescopes will be capable of albedo estimations for icy exomoons using their occultation light curves. The success of the measurements depends on the depth of the moon's occultation in the light curve and on the sensitivity of the used instruments. We applied simple calculations for different stellar masses in the V and J photometric bands, and compared the flux drop caused by the moon's occultation and the estimated photon noise of next generation missions with 5σ confidence. We found that albedo estimation by this method is not feasible for moons of solar-like stars, but small M dwarfs are better candidates for such measurements. Our calculations in the J photometric band show that E-ELT MICADO's photon noise is just about 4 ppm greater than the flux difference caused by an icy satellite twice the Earth's radius in a circular orbit at the snowline of an 0.1 stellar mass star. However, considering only photon noise underestimates the real expected noise, because other noise sources, such as CCD read-out and dark signal become significant in the near-infrared measurements. Hence we conclude that occultation measurements with next generation missions are far too challenging, even in the case of large, icy moons at the snowline of small M dwarfs. We also discuss the role of the parameters that were neglected in the calculations, for example inclination, eccentricity, orbiting direction of the moon. We predict that the first albedo estimations of exomoons will probably be made for large icy moons around the snowline of M4 - M9 type main sequence stars.

  11. Standards for the validation of remotely sensed albedo products

    NASA Astrophysics Data System (ADS)

    Adams, Jennifer

    2015-04-01

    Land surface albedo is important component of the Earth's energy balance, defined as the fraction of shortwave radiation absorbed by a surface, and is one many Essential Climate Variables (ECVS) that can be retrieved from space through remote sensing. To quantify the accuracy of these products, they must be validated with respect to in-situ measurements of albedo using an albedometer. Whilst accepted standards exist for the calibration of albedometers, standards for the use of in-situ measurement schemes, and their use in validation procedures have yet to be developed. It is essential that we can assess the quality of remotely sensed albedo data, and to identify traceable sources of uncertainty during process of providing these data. As a result of the current lack of accepted standards for in-situ albedo retrieval and validation procedures, we are not yet able to identify and quantify traceable sources of uncertainty. Establishing standard protocols for in-situ retrievals for the validation of global albedo products would allow inter-product use and comparison, in addition to product standardization. Accordingly, this study aims to assess the quality of in-situ albedo retrieval schemes and identify sources of uncertainty, specifically in vegetation environments. A 3D Monte Carlo Ray Tracing Model will be used to simulate albedometer instruments in complex 3D vegetation canopies. To determine sources of uncertainty, factors that influence albedo measurement uncertainty were identified and will subsequently be examined: 1. Time of day (Solar Zenith Angle) 2. Ecosytem type 3. Placement of albedometer within the ecosystem 4. Height of albedometer above the canopy 5. Clustering within the ecosystem A variety of 3D vegetation canopies have been generated to cover the main ecosystems found globally, different seasons, and different plant distributions. Canopies generated include birchstand and pinestand forests for summer and winter, savanna, shrubland, cropland and

  12. High-albedo materials for reducing building cooling energy use

    SciTech Connect

    Taha, H.; Sailor, D.; Akbari, H.

    1992-01-01

    One simple and effective way to mitigate urban heat islands, i.e., the higher temperatures in cities compared to those of the surrounds, and their negative impacts on cooling energy consumption is to use high-albedo materials on major urban surfaces such as rooftops, streets, sidewalks, school yards, and the exposed surfaces of parking lots. High-albedo materials can save cooling energy use by directly reducing the heat gain through a building's envelope (direct effect) and also by lowering the urban air temperature in the neighborhood of the building (indirect effect). This project is an attempt to address high-albedo materials for buildings and to perform measurements of roof coatings. We search for existing methods and materials to implement fighter colors on major building and urban surfaces. Their cost effectiveness are examined and the possible related technical, maintenance, and environmental problems are identified. We develop a method for measuring albedo in the field by studying the instrumentation aspects of such measurements. The surface temperature impacts of various albedo/materials in the actual outdoor environment are studied by measuring the surface temperatures of a variety of materials tested on an actual roof. We also generate an albedo database for several urban surfaces to serve as a reference for future use. The results indicate that high-albedo materials can have a large impact on the surface temperature regime. On clear sunny days, when the solar noon surface temperatures of conventional roofing materials were about 40{degrees}C (72{degrees}F) warmer than air, the surface temperature of high-albedo coatings were only about 5{degrees}C warmer than air. In the morning and in the late afternoon, the high-albedo materials were as cool as the air itself. While conventional roofing materials warm up by an average 0.055{degrees}C/(W m{sup {minus}2}), the high-albedo surfaces warm up by an average 0.015{degrees}C/(W m{sup {minus}2}).

  13. High-albedo materials for reducing building cooling energy use

    SciTech Connect

    Taha, H.; Sailor, D.; Akbari, H.

    1992-01-01

    One simple and effective way to mitigate urban heat islands, i.e., the higher temperatures in cities compared to those of the surrounds, and their negative impacts on cooling energy consumption is to use high-albedo materials on major urban surfaces such as rooftops, streets, sidewalks, school yards, and the exposed surfaces of parking lots. High-albedo materials can save cooling energy use by directly reducing the heat gain through a building`s envelope (direct effect) and also by lowering the urban air temperature in the neighborhood of the building (indirect effect). This project is an attempt to address high-albedo materials for buildings and to perform measurements of roof coatings. We search for existing methods and materials to implement fighter colors on major building and urban surfaces. Their cost effectiveness are examined and the possible related technical, maintenance, and environmental problems are identified. We develop a method for measuring albedo in the field by studying the instrumentation aspects of such measurements. The surface temperature impacts of various albedo/materials in the actual outdoor environment are studied by measuring the surface temperatures of a variety of materials tested on an actual roof. We also generate an albedo database for several urban surfaces to serve as a reference for future use. The results indicate that high-albedo materials can have a large impact on the surface temperature regime. On clear sunny days, when the solar noon surface temperatures of conventional roofing materials were about 40{degrees}C (72{degrees}F) warmer than air, the surface temperature of high-albedo coatings were only about 5{degrees}C warmer than air. In the morning and in the late afternoon, the high-albedo materials were as cool as the air itself. While conventional roofing materials warm up by an average 0.055{degrees}C/(W m{sup {minus}2}), the high-albedo surfaces warm up by an average 0.015{degrees}C/(W m{sup {minus}2}).

  14. Sea quark flavor asymmetry of hadrons in statistical balance model

    SciTech Connect

    Zhang Bin; Zhang Yongjun

    2010-10-01

    We suggested a Monte Carlo approach to simulate a kinetic equilibrium ensemble, and proved the equivalence to the linear equations method on equilibrium. With the convenience of the numerical method, we introduced variable splitting rates representing the details of the dynamics as model parameters which were not considered in previous works. The dependence on model parameters was studied, and it was found that the sea quark flavor asymmetry weakly depends on model parameters. It reflects the statistics principle, contributes the dominant part of the asymmetry, and the effect caused by details of the dynamics is small. We also applied the Monte Carlo approach of the statistical model to predict the theoretical sea quark asymmetries in kaons, octet baryons {Sigma}, {Xi}, and {Delta} baryons, even in exotic pentaquark states.

  15. Dental arch asymmetry

    PubMed Central

    Al-Zubair, Nabil Muhsen

    2014-01-01

    Objective: This study was conducted to assess the dental arch asymmetry in a Yemeni sample aged (18-25) years. Materials and Methods: The investigation involved clinical examination of 1479 adults; only 253 (129 females, 124 males) out of the total sample were selected to fulfill the criteria for the study sample. Study models were constructed and evaluated to measure mandibular arch dimensions. Three linear distances were utilized on each side on the dental arch: Incisal-canine distance, canine-molar distance and incisal-molar distance, which represent the dental arch segmental measurements. Results: When applying “t-test” at P < 0.05, no significant differences were found between the right and left canine-molar, incisal-canine and incisal-molar distances in both dental arches for both sexes. The greater variation (0.30 mm) was observed between right and left canine-molar distance in the maxillary dental arch in male and the smaller (0.04 mm) in the mandibular dental arch between the right and left canine-molar distance in females. Conclusion: The findings of the present study revealed a symmetrical pattern of dental arches, since the right and left sides showed no statistically significant difference. In general, it can be observed that the measurements related to the central incisors and canines have the widest range of reading and give the impression that the location of central incisor and canines to each other and to other teeth is the strongest factor in determining the dental arch asymmetry. PMID:24966774

  16. Preferential cooling of hot extremes from cropland albedo management

    PubMed Central

    Davin, Edouard L.; Seneviratne, Sonia I.; Ciais, Philippe; Olioso, Albert; Wang, Tao

    2014-01-01

    Changes in agricultural practices are considered a possible option to mitigate climate change. In particular, reducing or suppressing tillage (no-till) may have the potential to sequester carbon in soils, which could help slow global warming. On the other hand, such practices also have a direct effect on regional climate by altering the physical properties of the land surface. These biogeophysical effects, however, are still poorly known. Here we show that no-till management increases the surface albedo of croplands in summer and that the resulting cooling effect is amplified during hot extremes, thus attenuating peak temperatures reached during heat waves. Using a regional climate model accounting for the observed effects of no-till farming on surface albedo, as well as possible reductions in soil evaporation, we investigate the potential consequences of a full conversion to no-till agriculture in Europe. We find that the summer cooling from cropland albedo increase is strongly amplified during hot summer days, when surface albedo has more impact on the Earth’s radiative balance due to clear-sky conditions. The reduced evaporation associated with the crop residue cover tends to counteract the albedo-induced cooling, but during hot days the albedo effect is the dominating factor. For heatwave summer days the local cooling effect gained from no-till practice is of the order of 2 °C. The identified asymmetric impact of surface albedo change on summer temperature opens new avenues for climate-engineering measures targeting high-impact events rather than mean climate properties. PMID:24958872

  17. Preferential cooling of hot extremes from cropland albedo management.

    PubMed

    Davin, Edouard L; Seneviratne, Sonia I; Ciais, Philippe; Olioso, Albert; Wang, Tao

    2014-07-08

    Changes in agricultural practices are considered a possible option to mitigate climate change. In particular, reducing or suppressing tillage (no-till) may have the potential to sequester carbon in soils, which could help slow global warming. On the other hand, such practices also have a direct effect on regional climate by altering the physical properties of the land surface. These biogeophysical effects, however, are still poorly known. Here we show that no-till management increases the surface albedo of croplands in summer and that the resulting cooling effect is amplified during hot extremes, thus attenuating peak temperatures reached during heat waves. Using a regional climate model accounting for the observed effects of no-till farming on surface albedo, as well as possible reductions in soil evaporation, we investigate the potential consequences of a full conversion to no-till agriculture in Europe. We find that the summer cooling from cropland albedo increase is strongly amplified during hot summer days, when surface albedo has more impact on the Earth's radiative balance due to clear-sky conditions. The reduced evaporation associated with the crop residue cover tends to counteract the albedo-induced cooling, but during hot days the albedo effect is the dominating factor. For heatwave summer days the local cooling effect gained from no-till practice is of the order of 2 °C. The identified asymmetric impact of surface albedo change on summer temperature opens new avenues for climate-engineering measures targeting high-impact events rather than mean climate properties.

  18. Global Cooling: Effect of Urban Albedo on Global Temperature

    SciTech Connect

    Akbari, Hashem; Menon, Surabi; Rosenfeld, Arthur

    2007-05-22

    In many urban areas, pavements and roofs constitute over 60% of urban surfaces (roof 20-25%, pavements about 40%). The roof and the pavement albedo can be increased by about 0.25 and 0.10, respectively, resulting in a net albedo increase for urban areas of about 0.1. Many studies have demonstrated building cooling-energy savings in excess of 20% upon raising roof reflectivity from an existing 10-20% to about 60%. We estimate U.S. potential savings in excess of $1 billion (B) per year in net annual energy bills. Increasing albedo of urban surfaces can reduce the summertime urban temperature and improve the urban air quality. Increasing the urban albedo has the added benefit of reflecting more of the incoming global solar radiation and countering the effect of global warming. We estimate that increasing albedo of urban areas by 0.1 results in an increase of 3 x 10{sup -4} in Earth albedo. Using a simple global model, the change in air temperature in lowest 1.8 km of the atmosphere is estimated at 0.01K. Modelers predict a warming of about 3K in the next 60 years (0.05K/year). Change of 0.1 in urban albedo will result in 0.01K global cooling, a delay of {approx}0.2 years in global warming. This 0.2 years delay in global warming is equivalent to 10 Gt reduction in CO2 emissions.

  19. THE HIGH ALBEDO OF THE HOT JUPITER KEPLER-7 b

    SciTech Connect

    Demory, Brice-Olivier; Seager, Sara; Madhusudhan, Nikku; Kjeldsen, Hans; Christensen-Dalsgaard, Joergen; Gillon, Michael; Rowe, Jason F.; Borucki, William J.; Koch, David G.; Welsh, William F.; Adams, Elisabeth R.; Dupree, Andrea; McCarthy, Don; Kulesa, Craig

    2011-07-01

    Hot Jupiters are expected to be dark from both observations (albedo upper limits) and theory (alkali metals and/or TiO and VO absorption). However, only a handful of hot Jupiters have been observed with high enough photometric precision at visible wavelengths to investigate these expectations. The NASA Kepler mission provides a means to widen the sample and to assess the extent to which hot Jupiter albedos are low. We present a global analysis of Kepler-7 b based on Q0-Q4 data, published radial velocities, and asteroseismology constraints. We measure an occultation depth in the Kepler bandpass of 44 {+-} 5 ppm. If directly related to the albedo, this translates to a Kepler geometric albedo of 0.32 {+-} 0.03, the most precise value measured so far for an exoplanet. We also characterize the planetary orbital phase light curve with an amplitude of 42 {+-} 4 ppm. Using atmospheric models, we find it unlikely that the high albedo is due to a dominant thermal component and propose two solutions to explain the observed planetary flux. First, we interpret the Kepler-7 b albedo as resulting from an excess reflection over what can be explained solely by Rayleigh scattering, along with a nominal thermal component. This excess reflection might indicate the presence of a cloud or haze layer in the atmosphere, motivating new modeling and observational efforts. Alternatively, the albedo can be explained by Rayleigh scattering alone if Na and K are depleted in the atmosphere by a factor of 10-100 below solar abundances.

  20. Absolute magnitudes of asteroids and a revision of asteroid albedo estimates from WISE thermal observations

    NASA Astrophysics Data System (ADS)

    Pravec, Petr; Harris, Alan W.; Kušnirák, Peter; Galád, Adrián; Hornoch, Kamil

    2012-09-01

    We obtained estimates of the Johnson V absolute magnitudes (H) and slope parameters (G) for 583 main-belt and near-Earth asteroids observed at Ondřejov and Table Mountain Observatory from 1978 to 2011. Uncertainties of the absolute magnitudes in our sample are <0.21 mag, with a median value of 0.10 mag. We compared the H data with absolute magnitude values given in the MPCORB, Pisa AstDyS and JPL Horizons orbit catalogs. We found that while the catalog absolute magnitudes for large asteroids are relatively good on average, showing only little biases smaller than 0.1 mag, there is a systematic offset of the catalog values for smaller asteroids that becomes prominent in a range of H greater than ∼10 and is particularly big above H ∼ 12. The mean (Hcatalog - H) value is negative, i.e., the catalog H values are systematically too bright. This systematic negative offset of the catalog values reaches a maximum around H = 14 where the mean (Hcatalog - H) is -0.4 to -0.5. We found also smaller correlations of the offset of the catalog H values with taxonomic types and with lightcurve amplitude, up to ∼0.1 mag or less. We discuss a few possible observational causes for the observed correlations, but the reason for the large bias of the catalog absolute magnitudes peaking around H = 14 is unknown; we suspect that the problem lies in the magnitude estimates reported by asteroid surveys. With our photometric H and G data, we revised the preliminary WISE albedo estimates made by Masiero et al. (Masired, J.R. et al. [2011]. Astrophys. J. 741, 68-89) and Mainzer et al. (Mainzer, A. et al. [2011b]. Astrophys. J. 743, 156-172) for asteroids in our sample. We found that the mean geometric albedo of Tholen/Bus/DeMeo C/G/B/F/P/D types with sizes of 25-300 km is pV = 0.057 with the standard deviation (dispersion) of the sample of 0.013 and the mean albedo of S/A/L types with sizes 0.6-200 km is 0.197 with the standard deviation of the sample of 0.051. The standard errors of the

  1. A Continental United States High Resolution NLCD Land Cover – MODIS Albedo Database to Examine Albedo and Land Cover Change Relationships

    EPA Science Inventory

    Surface albedo influences climate by affecting the amount of solar radiation that is reflected at the Earth’s surface, and surface albedo is, in turn, affected by land cover. General Circulation Models typically use modeled or prescribed albedo to assess the influence of land co...

  2. Theoretical morphology and development of flight feather vane asymmetry with experimental tests in parrots.

    PubMed

    Feo, Teresa J; Prum, Richard O

    2014-06-01

    Asymmetry in flight feather vane width is a major functional innovation associated with the evolution of flight in the ancestors of birds. However, the developmental and morphological basis of feather shape is not simple, and the developmental processes involved in vane width asymmetry are poorly understood. We present a theoretical model of feather morphology and development that describes the possible ways to modify feather development and produce vane asymmetry. Our model finds that the theoretical morphospace of feather shape is redundant, and that many different combinations of parameters could be responsible for vane asymmetry in a given feather. Next, we empirically measured morphological and developmental model parameters in asymmetric and symmetric feathers from two species of parrots to identify which combinations of parameters create vane asymmetry in real feathers. We found that both longer barbs, and larger barb angles in the relatively wider trailing vane drove asymmetry in tail feathers. Developmentally, longer barbs were the result of an offset of the radial position of the new barb locus, whereas larger barb angles were produced by differential expansion of barbs as the feather unfurls from the tubular feather germ. In contrast, the helical angle of barb ridge development did not contribute to vane asymmetry and could be indicative of a constraint. This research provides the first comprehensive description of both the morphological and developmental modifications responsible for vane asymmetry within real feathers, and identifies key steps that must have occurred during the evolution of vane asymmetry.

  3. Albedo and Reflection Spectra of Extrasolar Giant Planets

    NASA Astrophysics Data System (ADS)

    Sudarsky, David; Burrows, Adam; Pinto, Philip

    2000-08-01

    We generate theoretical albedo and reflection spectra for a full range of extrasolar giant planet (EGP) models, from Jovian to 51 Pegasi class objects. Our albedo modeling utilizes the latest atomic and molecular cross sections, Mie theory treatment of scattering and absorption by condensates, a variety of particle size distributions, and an extension of the Feautrier technique, which allows for a general treatment of the scattering phase function. We find that, because of qualitative similarities in the compositions and spectra of objects within each of five broad effective temperature ranges, it is natural to establish five representative EGP albedo classes. At low effective temperatures (Teff<~150 K) is a class of ``Jovian'' objects (class I) with tropospheric ammonia clouds. Somewhat warmer class II, or ``water cloud,'' EGPs are primarily affected by condensed H2O. Gaseous methane absorption features are prevalent in both classes. In the absence of nonequilibrium condensates in the upper atmosphere, and with sufficient H2O condensation, class II objects are expected to have the highest visible albedos of any class. When the upper atmosphere of an EGP is too hot for H2O to condense, radiation generally penetrates more deeply. In these objects, designated class III or ``clear'' because of a lack of condensation in the upper atmosphere, absorption lines of the alkali metals, sodium and potassium, lower the albedo significantly throughout the visible. Furthermore, the near-infrared albedo is negligible, primarily because of strong CH4 and H2O molecular absorption and collision-induced absorption (CIA) by H2 molecules. In those EGPs with exceedingly small orbital distance (``roasters'') and 900 K<~Teff<~1500 K (class IV), a tropospheric silicate layer is expected to exist. In all but the hottest (Teff>~1500 K) or lowest gravity roasters, the effect of this silicate layer is likely to be insignificant because of the very strong absorption by sodium and potassium

  4. Relating black carbon content to reduction of snow albedo

    NASA Astrophysics Data System (ADS)

    Brandt, R. E.; Warren, S. G.; Clarke, A. D.

    2011-12-01

    In remote snow of the Northern Hemisphere, the levels of soot pollution are in the parts-per-billion (ppb) range, where the effect on albedo is at the level of a few percent. A reduction of albedo by 1-2% is significant for climate but is difficult to detect experimentally, because snow albedo depends on several other variables. In our work to quantify the climatic effect of black carbon (BC) in snow, we therefore do not directly measure the albedo reduction. Instead, we use a two-step procedure: (1) We collect snow samples, melt and filter them, and analyze the filters spectrophotometrically for BC concentration. (2) We use the BC amount from the filter measurement, together with snow grain size, in a radiative transfer model to compute the albedo reduction. Our radiative transfer model uses the discrete ordinates algorithm DISORT 2.0. We have chosen a representative BC size distribution and optical constants, and have incorporated those of mineral dust as well. While a given mass of BC causes over an order of magnitude more snow albedo reduction compared to dust, a snowpack containing dust mutes the albedo-reducing effect of BC. Because the computed reduction of snow albedo is model-based, it requires experimental verification. We doubt that direct measurement of albedo-reduction will be feasible in nature, because of the vertical variation of both snow grain size and soot content, and because the natural soot content is small. We conclude that what is needed is an artificial snowpack, with uniform grain size and large uniform soot content (ppm not ppb), to produce a large signal on albedo. We have chosen to pursue this experiment outdoors rather than in the laboratory, for the following reasons: (1) The snowpack in the field of view is uniformly illuminated if the source of radiation is the Sun. (2) Visible radiation penetrates into the snow, so photons emerge horizontally distant from where they entered. In the limited width of a laboratory snowpack, radiation

  5. Potential effects of forest management on surface albedo

    NASA Astrophysics Data System (ADS)

    Otto, J.; Bréon, F.-M.; Schelhaas, M.-J.; Pinty, B.; Luyssaert, S.

    2012-04-01

    Currently 70% of the world's forests are managed and this figure is likely to rise due to population growth and increasing demand for wood based products. Forest management has been put forward by the Kyoto-Protocol as one of the key instruments in mitigating climate change. For temperate and boreal forests, the effects of forest management on the stand-level carbon balance are reasonably well understood, but the biophysical effects, for example through changes in the albedo, remain elusive. Following a modeling approach, we aim to quantify the variability in albedo that can be attributed to forest management through changes in canopy structure and density. The modelling approach chains three separate models: (1) a forest gap model to describe stand dynamics, (2) a Monte-Carlo model to estimate the probability density function of the optical path length of photons through the canopy and (3) a physically-based canopy transfer model to estimate the interaction between photons and leaves. The forest gap model provides, on a monthly time step the position, height, diameter, crown size and leaf area index of individual trees. The Monte-Carlo model computes from this the probability density function of the distance a photon travels through crown volumes to determine the direct light reaching the forest floor. This information is needed by the canopy transfer model to calculate the effective leaf area index - a quantity that allows it to correctly represent a 3D process with a 1D model. Outgoing radiation is calculated as the result of multiple processes involving the scattering due to the canopy layer and the forest floor. Finally, surface albedo is computed as the ratio between incident solar radiation and calculated outgoing radiation. The study used two time series representing thinning from below of a beech and a Scots pine forest. The results show a strong temporal evolution in albedo during stand establishment followed by a relatively stable albedo once the canopy

  6. THE ALBEDOS OF KEPLER'S CLOSE-IN SUPER-EARTHS

    SciTech Connect

    Demory, Brice-Olivier

    2014-07-01

    Exoplanet research focusing on the characterization of super-Earths is currently limited to the handful of targets orbiting bright stars that are amenable to detailed study. This Letter proposes to look at alternative avenues to probe the surface and atmospheric properties of this category of planets, known to be ubiquitous in our galaxy. I conduct Markov Chain Monte Carlo light-curves analyses for 97 Kepler close-in R{sub P} ≲ 2.0 R {sub ⊕} super-Earth candidates with the aim of detecting their occultations at visible wavelengths. Brightness temperatures and geometric albedos in the Kepler bandpass are constrained for 27 super-Earth candidates. A hierarchical Bayesian modeling approach is then employed to characterize the population-level reflective properties of these close-in super-Earths. I find median geometric albedos A{sub g} in the Kepler bandpass ranging between 0.16 and 0.30, once decontaminated from thermal emission. These super-Earth geometric albedos are statistically larger than for hot Jupiters, which have medians A{sub g} ranging between 0.06 and 0.11. A subset of objects, including Kepler-10b, exhibit significantly larger albedos (A{sub g} ≳ 0.4). I argue that a better understanding of the incidence of stellar irradation on planetary surface and atmospheric processes is key to explain the diversity in albedos observed for close-in super-Earths.

  7. Spectral surface albedo derived from GOME-2/Metop measurements

    NASA Astrophysics Data System (ADS)

    Pflug, Bringfried; Loyola, Diego

    2009-09-01

    Spectral surface albedo is an important input for GOME-2 trace gas retrievals. An algorithm was developed for estimation of spectral surface albedo from top-of-atmosphere (TOA)-radiances measured by the Global Ozone Monitoring Experiment GOME-2 flying on-board MetOp-A. The climatologically version of this algorithm estimates Minimum Lambert-Equivalent Reflectivity (MLER) for a fixed time window and can use data of many years in contrast to the Near-real time version. Accuracy of surface albedo estimated by MLER-computation increases with the amount of available data. Unfortunately, most of the large GOME pixels are partly covered by clouds, which enhance the LER-data. A plot of LER-values over cloud fraction is used within this presentation to account for this influence of clouds. This "cloud fraction plot" can be applied over all surface types. Surface albedo obtained using the "cloud fraction plot" is compared with reference surface albedo spectra and with the FRESCO climatology. There is a general good agreement; however there are also large differences for some pixels.

  8. Climate change due to anthropogenic surface albedo modification

    SciTech Connect

    Potter, G.L.; Ellsaesser, H.W.; MacCracken, M.C.; Ellis, J.S.; Luther, F.M.

    1980-02-01

    Using a statistical dynamic climate model with more realistic surface albedo changes than used in previous experiments, we have conducted a numerical experiment combining desertification of the Sahara and deforestation of the tropical rain forest. Over an area of 9 x 10/sup 6/ km/sup 2/ at 20/sup 0/N the desert albedo was increased from 0.16 to 0.35 and over 7 x 10/sup 6/ km/sup 2/ at the equator and 10/sup 0/S the rain forest albedo was increased from 0.07 to 0.16. While the most significant direct climatic responses were observed in the modified zones, high northern latitudes exhibited the greatest cooling through activation of the ice-albedo feedback process. In contrast to Sagan et al., this experiment suggests that anthropogenic modification of surface albedo over the past few thousand years has had an impact on global climate which is likely quite small and probably undetectable.

  9. Gaussian quantum steering and its asymmetry in curved spacetime

    NASA Astrophysics Data System (ADS)

    Wang, Jieci; Cao, Haixin; Jing, Jiliang; Fan, Heng

    2016-06-01

    We study Gaussian quantum steering and its asymmetry in the background of a Schwarzschild black hole. We present a Gaussian channel description of quantum state evolution under the influence of Hawking radiation. We find that thermal noise introduced by the Hawking effect will destroy the steerability between an inertial observer Alice and an accelerated observer Bob who hovers outside the event horizon, while it generates steerability between Bob and a hypothetical observer anti-Bob inside the event horizon. Unlike entanglement behaviors in curved spacetime, here the steering from Alice to Bob suffers from a "sudden death" and the steering from anti-Bob to Bob experiences a "sudden birth" with increasing Hawking temperature. We also find that the Gaussian steering is always asymmetric and the maximum steering asymmetry cannot exceed ln 2 , which means the state never evolves to an extremal asymmetry state. Furthermore, we obtain the parameter settings that maximize steering asymmetry and find that (i) s =arccosh cosh/2r 1 -sinh2r is the critical point of steering asymmetry and (ii) the attainment of maximal steering asymmetry indicates the transition between one-way steerability and both-way steerability for the two-mode Gaussian state under the influence of Hawking radiation.

  10. CMB maximum temperature asymmetry axis: Alignment with other cosmic asymmetries

    NASA Astrophysics Data System (ADS)

    Mariano, Antonio; Perivolaropoulos, Leandros

    2013-02-01

    We use a global pixel-based estimator to identify the axis of the residual Maximum Temperature Asymmetry (MTA) (after the dipole subtraction) of the WMAP seven-year Internal Linear Combination (ILC) cosmic microwave background temperature sky map. The estimator is based on considering the temperature differences between opposite pixels in the sky at various angular resolutions (4°-15°) and selecting the axis that maximizes this difference. We consider three large-scale HEALPix resolutions: Nside=16(3.7°), Nside=8(7.3°) and Nside=4(14.7°). We compare the direction and magnitude of this asymmetry with three other cosmic asymmetry axes (α dipole, dark energy dipole and dark flow) and find that the four asymmetry axes are abnormally close to each other. We compare the observed MTA axis with the corresponding MTA axes of 104 Gaussian isotropic simulated ILC maps (based on ΛCDM). The fraction of simulated ILC maps that reproduce the observed magnitude of the MTA asymmetry and alignment with the observed α dipole is in the range of 0.1%-0.5% (depending on the resolution chosen for the cosmic microwave background map). The corresponding magnitude+alignment probabilities with the other two asymmetry axes (dark energy dipole and dark flow) are at the level of about 1%. We propose Extended Topological Quintessence as a physical model qualitatively consistent with this coincidence of directions.

  11. MORSE/STORM: A generalized albedo option for Monte Carlo calculations

    SciTech Connect

    Gomes, I.C.; Stevens, P.N. )

    1991-09-01

    The advisability of using the albedo procedure for the Monte Carlo solution of deep penetration shielding problems that have ducts and other penetrations has been investigated. The use of albedo data can dramatically improve the computational efficiency of certain Monte Carlo calculations. However, the accuracy of these results may be unacceptable because of lost information during the albedo event and serious errors in the available differential albedo data. This study was done to evaluate and appropriately modify the MORSE/BREESE package, to develop new methods for generating the required albedo data, and to extend the adjoint capability to the albedo-modified calculations. Major modifications to MORSE/BREESE include an option to save for further use information that would be lost at the albedo event, an option to displace the point of emergence during an albedo event, and an option to use spatially dependent albedo data for both forward and adjoint calculations, which includes the point of emergence as a new random variable to be selected during an albedo event. The theoretical basis for using TORT-generated forward albedo information to produce adjuncton albedos was derived. The MORSE/STORM package was developed to perform both forward and adjoint modes of analysis using spatially dependent albedo data. Results obtained with MORSE/STORM for both forward and adjoint modes were compared with benchmark solutions. Excellent agreement and improved computational efficiency were achieved, demonstrating the full utilization of the albedo option in the MORSE code. 7 refs., 17 figs., 15 tabs.

  12. Exploiting Surface Albedos Products to Bridge the Gap Between Remote Sensing Information and Climate Models

    NASA Astrophysics Data System (ADS)

    Pinty, Bernard; Andredakis, Ioannis; Clerici, Marco; Kaminski, Thomas; Taberner, Malcolm; Stephen, Plummer

    2011-01-01

    We present results from the application of an inversion method conducted using MODIS derived broadband visible and near-infrared surface albedo products. This contribution is an extension of earlier efforts to optimally retrieve land surface fluxes and associated two- stream model parameters based on the Joint Research Centre Two-stream Inversion Package (JRC-TIP). The discussion focuses on products (based on the mean and one-sigma values of the Probability Distribution Functions (PDFs)) obtained during the summer and winter and highlight specific issues related to snowy conditions. This paper discusses the retrieved model parameters including the effective Leaf Area Index (LAI), the background brightness and the scattering efficiency of the vegetation elements. The spatial and seasonal changes exhibited by these parameters agree with common knowledge and underscore the richness of the high quality surface albedo data sets. At the same time, the opportunity to generate global maps of new products, such as the background albedo, underscores the advantages of using state of the art algorithmic approaches capable of fully exploiting accurate satellite remote sensing datasets. The detailed analyses of the retrieval uncertainties highlight the central role and contribution of the LAI, the main process parameter to interpret radiation transfer observations over vegetated surfaces. The posterior covariance matrix of the uncertainties is further exploited to quantify the knowledge gain from the ingestion of MODIS surface albedo products. The estimation of the radiation fluxes that are absorbed, transmitted and scattered by the vegetation layer and its background is achieved on the basis of the retrieved PDFs of the model parameters. The propagation of uncertainties from the observations to the model parameters is achieved via the Hessian of the cost function and yields a covariance matrix of posterior parameter uncertainties. This matrix is propagated to the radiation

  13. Numerical investigation of the single scattering albedo of radiant energy passing through polydisperse crystalline media

    NASA Astrophysics Data System (ADS)

    Shefer, O. V.; Shefer, V. A.; Sinyukova, E. A.

    2014-12-01

    Studies of the role of atmospheric formations and cosmic dust clouds in the transmission of radiation is one of the most uncertain and difficult problems in astrophysics and climatology. One of the main tasks of practical astrophysics is the interpretation of the results of observations of space objects. There is a necessity of describing the propagation of electromagnetic waves in the environment. In this paper, applying the numerical methods, we study the optical characteristics of polydisperse media consisting of randomly oriented and preferentially oriented crystals, taking into account the distribution function of particle sizes. Particles of spherical shape and ensembles preferentially oriented plate crystals are considered as models. Mie theory and method of physical optics are used to calculate the scattering characteristics. Numerical study of the effects of extinction, scattering and absorption on the single scattering albedo of radiation allowed us to establish the basic patterns of the passage of radiant energy through a translucent medium. At the visible range of wavelengths, both for small and large particles, the single scattering albedo is almost equal to 1. The spectral course of this optical performance is mainly determined by the refractive index of the particles. Features of wave dependence of single scattering albedo are associated with microphysical parameters of the environment, which are more pronounced when the attenuation of the radiation is determined mainly by the scattering. Higher values of the absorption index and optical thickness of the crystal reduce the value of the single scattering albedo, smoothing the features of its spectral course. Values of the absorption index of substance, as value of the order of 0.1, do not lead to a decrease of the single scattering albedo as it is less than 0.5. This allows us to conclude that we should not neglect the microphysical characteristics of the crystals even by strong absorption of radiant

  14. Estimation of Sub Hourly Glacier Albedo Values Using Artificial Intelligence Techniques

    NASA Astrophysics Data System (ADS)

    Moya Quiroga, Vladimir; Mano, Akira; Asaoka, Yoshihiro; Udo, Keiko; Kure, Shuichi; Mendoza, Javier

    2013-04-01

    Glaciers are the most important fresh water reservoirs storing about 67% of total fresh water. Unfortunately, they are retreating and some small glaciers have already disappeared. Thus, snow glacier melt (SGM) estimation plays an important role in water resources management. Whether SGM is estimated by complete energy balance or a simplified method, albedo is an important data present in most of the methods. However, this is a variable value depending on the ground surface and local conditions. The present research presents a new approach for estimating sub hourly albedo values using different artificial intelligence techniques such as artificial neural networks and decision trees along with measured and easy to obtain data. . The models were developed using measured data from the Zongo-Ore station located in the Bolivian tropical glacier Zongo (68°10' W, 16°15' S). This station automatically records every 30 minutes several meteorological parameters such as incoming short wave radiation, outgoing short wave radiation, temperature or relative humidity. The ANN model used was the Multi Layer Perceptron, while the decision tree used was the M5 model. Both models were trained using the WEKA software and validated using the cross validation method. After analysing the model performances, it was concluded that the decision tree models have a better performance. The model with the best performance was then validated with measured data from the Equatorian tropical glacier Antizana (78°09'W, 0°28'S). The model predicts the sub hourly albedo with an overall mean absolute error of 0.103. The highest errors occur for albedo measured values higher than 0.9. Considering that this is an extreme value coincident with low measured values of incoming short wave radiation, it is reasonable to assume that such values include errors due to censored data. Assuming a maximum albedo of 0.9 improved the accuracy of the model reducing the MAE to less than 0.1. Considering that the

  15. Quality assessment and improvement of the EUMETSAT Meteosat Surface Albedo dataset

    NASA Astrophysics Data System (ADS)

    Lattanzio, Alessio; Fell, Frank; Bennartz, Ralf; Muller, Jan-Peter; Trigo, Isabel; Löw, Alexander; Schulz, Jörg

    2015-04-01

    Surface albedo is an important parameter for quantifying and understanding the nature of the Earth's radiation budget. This study describes a comprehensive validation of the EUMETSAT Meteosat Surface Albedo (MSA) Climate Data Record (CDR) currently comprising up to 24 years (1982-2006) of continuous surface albedo coverage for large areas covering Africa, Europe and western parts of Asia. In addition it is discussing retrieval improvements as a consequence of the validation results. The MSA CDR has been generated within a project of the WMO entitled Sustained and Coordinated Processing of Environmental Satellite Data for Climate Monitoring (SCOPE-CM) initiative. The MSA CDR went into a two step validation process. Firstly, the satellite product has been compared to available in situ and satellite data assessing systematic and random deviations among the products. This also included an assessment of the temporal stability over desert sites that are assumed to remain stable over time. Furthermore impact on product quality due to anisotropic effects or snow covered surfaces has been analysed. The evaluation has revealed a number of specific strengths and weaknesses. The long-term consistency is very high and meets the Global Climate Observing System (GCOS) stability requirements for desert reference sites. The limitation in quality appears to be due primarily to clouds not removed by the embedded cloud screening procedure as the most significant weakness of the retrieval process. Two alternative strategies are followed to efficiently improve the cloud detection and removal. The first is based on the application of a robust and reliable cloud mask during the retrieval taking advantage of the information contained in the measurements of the infrared and visible bands. The second, in order to screen out outlier values, relies on a post processing analysis of the albedo seasonal variation together with the usage of "a priori" information contained in a background albedo

  16. NEOWISE Reactivation Mission Year One: Preliminary Asteroid Diameters and Albedos

    NASA Astrophysics Data System (ADS)

    Nugent, Carolyn; Mainzer, A.; Masiero, J. R.; Bauer, J.; Cutri, R. M.; Grav, T.; Kramer, E.; Sonnett, S.; Stevenson, R.; Wright, E.

    2015-11-01

    The infrared NEOWISE project (Mainzer et al. 2011a) has measured diameters and albedos for ˜20% of the known asteroid population, the majority of these measurements to date (Mainzer et al. 2011b, 2012, 2015; Masiero et al. 2011, 2012; Grav et al. 2011, 2012a; Bauer et al. 2013). Here, we expand the number of asteroids characterized by NEOWISE, deriving diameters and albedos for 7,959 asteroids detected between December 13, 2013, and December 13, 2014 during the first year of the Reactivation mission. 7,758 are Main Belt or Mars-crossing asteroids. 17% of these objects have not been previously characterized using WISE or NEOWISE thermal measurements. Diameters are determined to an accuracy of ~20% or better. If good-quality H magnitudes are available, albedos can be determined to within ~40% or better.

  17. A new parameterization of spectral and broadband ocean surface albedo.

    PubMed

    Jin, Zhonghai; Qiao, Yanli; Wang, Yingjian; Fang, Yonghua; Yi, Weining

    2011-12-19

    A simple yet accurate parameterization of spectral and broadband ocean surface albedo has been developed. To facilitate the parameterization and its applications, the albedo is parameterized for the direct and diffuse incident radiation separately, and then each of them is further divided into two components: the contributions from surface and water, respectively. The four albedo components are independent of each other, hence, altering one will not affect the others. Such a designed parameterization scheme is flexible for any future update. Users can simply replace any of the adopted empirical formulations (e.g., the relationship between foam reflectance and wind speed) as desired without a need to change the parameterization scheme. The parameterization is validated by in situ measurements and can be easily implemented into a climate or radiative transfer model.

  18. Moon: lunar albedo for soft x-rays

    NASA Astrophysics Data System (ADS)

    Ibadov, Subhon

    2016-07-01

    Albedo of the Moon for soft X-rays (0.1-2 keV photons) is determined on the basis of the X-ray luminosity of the Moon detected and measured for the first time by orbital space telescope ROSAT in 1990. It is found that the lunar albedo for the solar soft X-rays is less than the lunar visual region albedo almost thousand times. The data allow to estimate more correctly X-ray luminosity of dusty comets like Hyakutake C/1996 B2 and Hale-Bopp C/1995 O1 due to scattering of solar soft X-rays and to reveal thus the dominant mechanism for production of X-rays in dusty comets.

  19. Impact of CP-violation on neutrino lepton number asymmetries revisited

    NASA Astrophysics Data System (ADS)

    Barenboim, Gabriela; Park, Wan-Il

    2017-02-01

    We revisit the effect of the (Dirac) CP-violating phase on neutrino lepton number asymmetries in both mass- and flavor-basis. We found that, even if there are sizable effects on muon- and tau-neutrino asymmetries, the effect on the asymmetry of electron-neutrinos is at most similar to the upper bound set by BBN for initial neutrino degeneracy parameters smaller than order unity. We also found that, for the asymmetries in mass-basis, the changes caused by CP-violation is of sub-% level which is unlikely to be accessible neither in the current nor in the forthcoming experiments.

  20. [Dreams and interhemispheric asymmetry].

    PubMed

    Korabel'nikova, E A; Golubev, V L

    2001-01-01

    The dreams of 103 children and adolescents, aged 10-17 years, have been studied. The test group included 78 patients with neurotic disorders; control one consisted of 25 healthy subjects. Dream features, which were common for those with preferentially left asymmetry profile both in patients as well as in healthy subjects, were: less expressed novelty factor and frequent appearance of rare phenomena, such as "déjà vu in wakefulness", reality, "mixed" (overlapped) dreams, prolonged dreams in repeat sleep, frequent changes of personages and scenes of action. Left-hander dream peculiarities, being detected only in neurotic patients but not in healthy subjects, emerged as lucid phenomena deficit, "dream in dreams" and "dream reminiscence in dream" syndrome, which have been found only in left-handers. Right and left hemispheres seem to contribute in different ways to a dream formation. In authors believe that the left hemisphere seems to provide dream origin while the right hemisphere provides dream vividness, figurativeness and affective activation level.

  1. Asymmetry and dyslexia.

    PubMed

    Leonard, Christiana M; Eckert, Mark A

    2008-01-01

    Developmental language disorders are characterized by a maturational trajectory that deviates or lags that of normal children. Given the wide variation in the rate of normal language development, diagnosis and classification of these disorders poses severe problems for the clinician. Our laboratory has been searching for anatomical signatures that could aid the development of a neurobiologically based classification. Quantitative analysis of the magnetic resonance imaging (MRI) brain scans of a series of samples of children and adults with reading and language disorders has identified two clusters with contrasting anatomical and reading profiles. Individuals with small symmetrical brain structures tend to have deficits in multiple domains of written and oral language whereas those with larger asymmetrical structures are more likely to have the isolated phonological deficits seen in adults with compensated dyslexia. Surprisingly, the anatomical risk factors that define these clusters do not form a continuum of increasing severity but deviate in opposite directions from normal. Individuals with moderate brain size and asymmetry typically demonstrate the best overall performance. Further research should determine if phonological impairments in the two clusters are associated with differing genetic and environmental risk factors requiring different types of intervention.

  2. Detailed spatiotemporal albedo observations at Greenland's Mittivakkat Gletscher

    NASA Astrophysics Data System (ADS)

    Mernild, Sebastian H.; Knudsen, Niels T.; Yde, Jacob C.; Malmros, Jeppe K.

    2015-04-01

    Surface albedo is defined as the reflected fraction of incoming solar shortwave radiation at the surface. On Greenland's Mittivakkat Gletscher the mean glacier-wide MODIS-estimated albedo dropped by 0.10 (2000-2013) from 0.43 to 0.33 by the end of the mass balance year (EBY). Hand-held albedo measurements as low as 0.10 were observed over debris-covered ice at the glacier margin at the EBY: these values were slightly below observed values for proglacial bedrock (~0.2). The albedo is highly variable in space - a significant variability occurred within few meters at the glacier margin area ranging from 0.10 to 0.39 due to variability in debris-cover thickness and composition, microbial activity (including algae and cyanobacteria), snow grain crystal metamorphism, bare ice exposure, and meltwater ponding. Huge dark-red-brown-colored ice algae colonies were observed. Albedo measurements on snow patches and bare glacier ice changed significant with increasing elevations (180-600 m a.s.l.) by lapse rates of 0.04 and 0.03 per 100 m, respectively, indicating values as high as 0.82 and 0.40 on the upper part of the glacier. Over a period of two weeks from early August to late August 2014 the hand-held observed mean glacier-wide albedo changed from 0.40 to 0.30 indicating that on average 10% more incoming solar shortwave radiation became available for surface ablation at the end of the melt season.

  3. Beam normal spin asymmetries: Theory

    SciTech Connect

    M. Vanderhaeghen

    2007-06-01

    The beam normal spin asymmetry in elastic electron-nucleon scattering is discussed. This beam normal spin asymmetry depends on the imaginary part of two-photon exchange processes between electron and nucleon, and measures the non-forward structure functions of the nucleon. After briefly reviewing the theoretical formalism, we discuss calculations in the threshold region, in the resonance region, as well as in the diffractive region, corresponding with high energy and forward angles.

  4. NEOWISE REACTIVATION MISSION YEAR ONE: PRELIMINARY ASTEROID DIAMETERS AND ALBEDOS

    SciTech Connect

    Nugent, C. R.; Cutri, R. M.; Mainzer, A.; Masiero, J.; Bauer, J.; Kramer, E.; Sonnett, S.; Stevenson, R.; Grav, T.; Wright, E. L.

    2015-12-01

    We present preliminary diameters and albedos for 7956 asteroids detected in the first year of the NEOWISE Reactivation mission. Of those, 201 are near-Earth asteroids and 7755 are Main Belt or Mars-crossing asteroids. 17% of these objects have not been previously characterized using the Near-Earth Object Wide-field Infrared Survey Explorer, or “NEOWISE” thermal measurements. Diameters are determined to an accuracy of ∼20% or better. If good-quality H magnitudes are available, albedos can be determined to within ∼40% or better.

  5. Comparative global albedo and color maps of the Uranian satellites

    NASA Astrophysics Data System (ADS)

    Buratti, B. J.; Mosher, J. A.

    1991-03-01

    The surfaces of the Uranian satellites Ariel, Miranda, Oberon, Titania, and Umbriel are characterized on the basis of Voyager observations. Tables of spectrophotometric data and maps of normal reflectances, green/violet ratios, and possible geological formations are presented and discussed in detail. Variations in albedo are found to be associated with impact features, and it is inferred from color differences that the upper surface of Ariel contains a higher proportion of redder material (tentatively identified as accreted low-albedo meteoritic dust) than those of the other moons.

  6. Comparative global albedo and color maps of the Uranian satellites

    SciTech Connect

    Buratti, B.J.; Mosher, J.A. )

    1991-03-01

    The surfaces of the Uranian satellites Ariel, Miranda, Oberon, Titania, and Umbriel are characterized on the basis of Voyager observations. Tables of spectrophotometric data and maps of normal reflectances, green/violet ratios, and possible geological formations are presented and discussed in detail. Variations in albedo are found to be associated with impact features, and it is inferred from color differences that the upper surface of Ariel contains a higher proportion of redder material (tentatively identified as accreted low-albedo meteoritic dust) than those of the other moons. 42 refs.

  7. Measurement of photon-energy albedo from stratified shielding materials.

    PubMed

    Sinha, A K; Bhattacharjee, A

    1991-11-01

    In the conventional method of measuring photon-energy albedo using a scintillation detector coupled with a multichannel analyzer, tedious efficiency correction by the inverse matrix method was needed. The indigenously designed proportional-response photon counter, with its detection efficiency proportional to energy of incident photons, was used in the present investigation. Use of the proportional-response photon counter makes the measurement straightforward and more accurate. Measurements of energy albedo from stratified layers of aluminum, iron, lead, and concrete using 662-keV and 1250-keV photon energies are reported.

  8. Investigation of albedo neutrons by the Intercosmos-17 satellite

    NASA Astrophysics Data System (ADS)

    Dubinskii, Iu.; Efimov, Iu. E.; Kudela, K.; Mikhaeli, L.; Roiko, I.; Chichikaliuk, Iu. A.

    1982-09-01

    Measurements were made with the Intercosmos-17 scintillation counter in 1977 in order to investigate the contribution of albedo neutrons with energies of 1-30 MeV to the formation of radiation-belt protons of corresponding energies. The differential current density of albedo neutrons is presented for the invariant latitude of 42.7 deg during a quiet period of solar activity (October 8-10, 1977). The following value is obtained for this differential current density: I0 (1 MeV) = 0.104 + or - 0.023 neutrons/sq cm s MeV.

  9. Comparative global albedo and color maps of the Uranian satellites

    NASA Technical Reports Server (NTRS)

    Buratti, Bonnie J.; Mosher, Joel A.

    1991-01-01

    The surfaces of the Uranian satellites Ariel, Miranda, Oberon, Titania, and Umbriel are characterized on the basis of Voyager observations. Tables of spectrophotometric data and maps of normal reflectances, green/violet ratios, and possible geological formations are presented and discussed in detail. Variations in albedo are found to be associated with impact features, and it is inferred from color differences that the upper surface of Ariel contains a higher proportion of redder material (tentatively identified as accreted low-albedo meteoritic dust) than those of the other moons.

  10. Transformation of surface albedo to surface: Atmosphere surface and irradiance, and their spectral and temporal averages

    NASA Technical Reports Server (NTRS)

    Nack, M. L.; Curran, R. J.

    1978-01-01

    The dependence of the albedo at the top of a realistic atmosphere upon the surface albedo, solar zenith angle, and cloud optical thickness is examined for the cases of clear sky, total cloud cover, and fractional cloud cover. The radiative transfer calculations of Dave and Braslau (1975) for particular values of surface albedo and solar zenith angle, and a single value of cloud optical thickness are used as the basis of a parametric albedo model. The question of spectral and temporal averages of albedos and reflected irradiances is addressed, and unique weighting functions for the spectral and temporal albedo averages are developed.

  11. Cerebral asymmetry in insomnia sufferers.

    PubMed

    St-Jean, Geneviève; Turcotte, Isabelle; Bastien, Célyne H

    2012-01-01

    Cerebral asymmetry is used to describe the differences in electroencephalographic activity between regions of the brain. The objective of this study was to document frontal, central, and parietal asymmetry in psychophysiological (Psy-I) and paradoxical (Para-I) insomnia sufferers as well as good sleeper (GS) controls, and to compare their patterns of asymmetry to others already found in anxiety and depression. Additionally, asymmetry variations between nights were assessed. Participants were 17 Psy-I, 14 Para-I, and 19 GS (mean age = 40 years, SD = 9.4). They completed three nights of polysomnography (PSG) recordings following a clinical evaluation in a sleep laboratory. All sleep cycles of Nights 2 and 3 were retained for power spectral analysis. The absolute activity in frequency bands (0.00-125.00 Hz) was computed at multiple frontal, central, and parietal sites in rapid eye movement and non-rapid eye movement sleep to provide cerebral asymmetry measures. Mixed model ANOVAs were computed to assess differences between groups and nights. Correlations were performed with asymmetry and symptoms of depression and anxiety from self-reported questionnaires. Over the course of the two nights, Para-I tended to present hypoactivation of their left frontal region but hyperactivation of their right one compared with GS. As for Psy-I, they presented increased activation of their right parietal region compared with Para-I. Asymmetry at frontal, central, and parietal region differed between nights. On a more disrupted night of sleep, Psy-I had increased activity in their right parietal region while Para-I presented a decrease in cerebral activity in the right central region on their less disrupted night of sleep. Anxious and depressive symptoms did not correlate with asymmetry at any region. Therefore, Psy-I and Para-I present unique patterns of cerebral asymmetry that do not relate to depression or anxiety, and asymmetry varies between nights, maybe as a

  12. Deformity, Erosion, Lesion, and Tumor Occurrence, Fluctuating Asymmetry, and Population Parameters for Bluntnose Minnow (Pimephales notatus) as Indicators of Recovering Water Quality in a Great Lakes Area of Concern, USA.

    PubMed

    Simon, Thomas P; Burskey, Jacob L

    2016-02-01

    The Grand Calumet River is an industrial river and a Great Lakes Area of Concern in southwestern Lake Michigan, USA. Recovery end points require well-formulated designs to assess the use of occurrence of internal and external anomalies, fluctuating asymmetry, and population indicators to determine recovery from the water-quality Beneficial Use Impairments of fish tumors and deformities. A paired-watershed approach using three reaches within the study area was sampled weekly and separated into near- and far-field reaches, whereas the Little Calumet River, Indiana Dunes National Lakeshore, served as a control. Field-collected Pimephales notatus were inspected for occurrence of deformities, erosion, lesion, and tumor (DELT) anomalies, measured for body symmetry, and dissected to ascertain sex and the condition of internal organs. Morphometric measurements (p ≤ 0.000), internal organ conditions (p = 0.001), and sex ratios of the fish (p = 0.001) were significantly different between the control and P. notatus test populations. The near-field individuals had the highest incidence of DELT occurrence (70 %) followed by the far-field reaches at Roxana Marsh (45 %) and Kennedy Avenue (41.9 %). Morphometric analysis showed significant differences between body size and shape and age class structure between populations. No test-reach individual lived to reach age >2 years. Gonads and livers from Grand Calumet individuals were found to be blackened, ruptured, and decreased in thickness. None of the fish from test study reaches displayed sexual structure in a 1:1 ratio. High sediment-contaminant concentrations for polycyclic aromatic hydrocarbon metals in the Grand Calumet River correlated (r (2) = 0.998) with decreased population fitness and decreased individual reproductive health.

  13. Measurements and modelling of snow particle size and shortwave infrared albedo over a melting Antarctic ice sheet

    NASA Astrophysics Data System (ADS)

    Pirazzini, R.; Räisänen, P.; Vihma, T.; Johansson, M.; Tastula, E.-M.

    2015-06-01

    The albedo of a snowpack depends on the single-scattering properties of individual snow crystals, which have a variety of shapes and sizes, and are often bounded in clusters. From the point of view of optical modelling, it is essential to identify the geometric dimensions of the population of snow particles that synthetize the scattering properties of the snowpack surface. This involves challenges related to the complexity of modelling the radiative transfer in such an irregular medium, and to the difficulty of measuring microphysical snow properties. In this paper, we illustrate a method to measure the size distribution of a snow particle parameter, which roughly corresponds to the smallest snow particle dimension, from two-dimensional macro-photos of snow particles taken in Antarctica at the surface layer of a melting ice sheet. We demonstrate that this snow particle metric corresponds well to the optically equivalent effective radius utilized in radiative transfer modelling, in particular when snow particles are modelled with the droxtal shape. The surface albedo modelled on the basis of the measured snow particle metric showed an excellent match with the observed albedo when there was fresh or drifted snow at the surface. In the other cases, a good match was present only for wavelengths longer than 1.4 μm. For shorter wavelengths, our modelled albedo generally overestimated the observations, in particular when surface hoar and faceted polycrystals were present at the surface and surface roughness was increased by millimetre-scale cavities generated during melting. Our results indicate that more than just one particle metric distribution is needed to characterize the snow scattering properties at all optical wavelengths, and suggest an impact of millimetre-scale surface roughness on the shortwave infrared albedo.

  14. Measurements and modelling of snow particle size and shortwave infrared albedo over a melting Antarctic ice sheet

    NASA Astrophysics Data System (ADS)

    Pirazzini, R.; Räisänen, P.; Vihma, T.; Johansson, M.; Tastula, E.-M.

    2015-12-01

    The albedo of a snowpack depends on the single-scattering properties of individual snow crystals, which have a variety of shapes and sizes, and are often bounded in clusters. From the point of view of optical modelling, it is essential to identify the geometric dimensions of the population of snow particles that synthesize the scattering properties of the snowpack surface. This involves challenges related to the complexity of modelling the radiative transfer in such an irregular medium, and to the difficulty of measuring microphysical snow properties. In this paper, we illustrate a method to measure the size distribution of a snow particle parameter, which roughly corresponds to the smallest snow particle dimension, from two-dimensional macro photos of snow particles taken in Antarctica at the surface layer of a melting ice sheet. We demonstrate that this snow particle metric corresponds well to the optically equivalent effective radius utilized in radiative transfer modelling, in particular when snow particles are modelled with the droxtal shape. The surface albedo modelled on the basis of the measured snow particle metric showed an excellent match with the observed albedo when there was fresh or drifted snow at the surface. In the other cases, a good match was present only for wavelengths longer than 1.4 μm. For shorter wavelengths, our modelled albedo generally overestimated the observations, in particular when surface hoar and faceted polycrystals were present at the surface and surface roughness was increased by millimetre-scale cavities generated during melting. Our results indicate that more than just one particle metric distribution is needed to characterize the snow scattering properties at all optical wavelengths, and suggest an impact of millimetre-scale surface roughness on the shortwave infrared albedo.

  15. Evaluation of Satellite Based Estimates of Surface Albedo with Ground and Aircraft Observations in a Semi-Arid Region

    NASA Astrophysics Data System (ADS)

    Kassabova, T. D.; Pinker, R. T.; Keefer, T.; Goodrich, D.; Huete, A.; Privette, J.

    2002-05-01

    Surface albedo is an important climate parameter needed for applications that deal with the disposition of radiant energy in the atmosphere and at the surface. Global or large-scale observations of surface albedo are not available, and therefore, it is being monitored from space born instruments. There are trade-offs in the capabilities of the different observational systems. Most satellite sensors are narrow-band and of low temporal resolution, while at a wide range of spatial resolutions. In this study we attempt to derive the surface albedo from two operational satellites, namely a geostationary (GOES-8), and a polar orbiter (NOAA-14), and compare the results with ground-based measurements, as well as with aircraft surveys. Models of atmospheric radiative transfer provide the tools for simulating the broadband and the narrow-band radiances at the top of the atmosphere, and for performing atmospheric corrections. Derived will be angularly and seasonally-dependant relationships between narrowband reflectance and broadband albedo, and the methodology will be tested at the semi-arid USDA-ARS Walnut Gulch Experimental Watershed in Arizona, which serves as a validation site for many space missions, such as ADEOS-II and MODLAND. Specifically, the angularly dependent MODTRAN 3.7 model is used for the simulations. The simulations are performed for 10 solar zenith angles, 6 zenith and 8 azimuth angles, using 5 climatological profiles for temperature, water vapor and ozone for each season derived form the TIGR profiles modified by the Forecast System Laboratory (FSL) rawiosonde information. In the simulations, a spectral surface reference albedo model for open shrub-land is used for each season. It is planned to expand the simulations to additional satellite sensors, such as the GLI on ADEOS II, to facilitate comparison from this mission with operational sensors.

  16. Model test of CCN-cloud albedo climate forcing

    NASA Technical Reports Server (NTRS)

    Ghan, S. J.; Taylor, K. E.; Penner, J. E.; Erickson, D. J., III

    1990-01-01

    Cloud condensation nuclei (CCN) influence cloud albedo through their effect on the cloud droplet size distribution. A number of studies have evaluated the climatic impact of the CCN-cloud albedo feedback, but all have assumed that cloud distributions, cloud thicknesses, and cloud liquid water contents would remain constant as the climate adjusted. This assumption has been tested using the Livermore version of the National Center for Atmospheric Research Community Climate Model. The results indicate that there are no significant compensating changes in cloud properties that would counteract the 1.7 percent global albedo increase resulting from a fourfold increase in marine CCN concentration. Furthermore, when ocean surface temperatures are decreased 4 C in a manner broadly consistent with the enhanced cloud albedos, an increase in cloud fraction of 3.5 percent and a reduction in cloud altitude are predicted, leading to a positive feedback from clouds that would imply a climate impact roughly double that calculated from cloud droplet size distribution change alone.

  17. Detection of light transformations and concomitant changes in surface albedo.

    PubMed

    Gerhard, Holly E; Maloney, Laurence T

    2010-07-16

    We report two experiments demonstrating that (1) observers are sensitive to information about changes in the light field not captured by local scene statistics and that (2) they can use this information to enhance detection of changes in surface albedo. Observers viewed scenes consisting of matte surfaces at many orientations illuminated by a collimated light source. All surfaces were achromatic, all lights neutral. In the first experiment, observers attempted to discriminate small changes in direction of the collimated light source (light transformations) from matched changes in the albedos of all surfaces (non-light transformations). Light changes and non-light changes shared the same local scene statistics and edge ratios, but the latter were not consistent with any change in direction to the collimated source. We found that observers could discriminate light changes as small as 5 degrees with sensitivity d' > 1 and accurately judge the direction of change. In a second experiment, we measured observers' ability to detect a change in the surface albedo of an isolated surface patch during either a light change or a surface change. Observers were more accurate in detecting isolated albedo changes during light changes. Measures of sensitivity d' were more than twice as great.

  18. Albedo and color maps of the Saturnian satellites

    NASA Technical Reports Server (NTRS)

    Buratti, Bonnie J.; Mosher, Joel A.; Johnson, Torrence V.

    1990-01-01

    The paper discusses the production of maps of the albedos and colors of Mimas, Enceladus, Tethys, Dione, and Rhea over the full range of their imaged surfaces. Voyager images were used to prepare maps of the normal reflectances and color ratios (0.58/0.41 micron) of these satelites.

  19. Variable control of neutron albedo in toroidal fusion devices

    DOEpatents

    Jassby, D.L.; Micklich, B.J.

    1983-06-01

    This invention pertains to methods of controlling in the steady state, neutron albedo in toroidal fusion devices, and in particular, to methods of controlling the flux and energy distribution of collided neutrons which are incident on an outboard wall of a toroidal fusion device.

  20. Albedo Study of the Depositional Fans Associated with Martian Gullies

    NASA Astrophysics Data System (ADS)

    Craig, J.; Sears, D. W. G.

    2005-03-01

    This work is a two-part investigation of the albedo of the depositional aprons or fans associated with Martian gully features. Using Adobe Systems Photoshop 5.0 software we analyzed numerous Mars Global Surveyor MOC and Mars Odyssey THEMIS images.

  1. Assessing modeled Greenland surface mass balance in the GISS Model E2 and its sensitivity to surface albedo

    NASA Astrophysics Data System (ADS)

    Alexander, Patrick; LeGrande, Allegra N.; Koenig, Lora S.; Tedesco, Marco; Moustafa, Samiah E.; Ivanoff, Alvaro; Fischer, Robert P.; Fettweis, Xavier

    2016-04-01

    The surface mass balance (SMB) of the Greenland Ice Sheet (GrIS) plays an important role in global sea level change. Regional Climate Models (RCMs) such as the Modèle Atmosphérique Régionale (MAR) have been employed at high spatial resolution with relatively complex physics to simulate ice sheet SMB. Global climate models (GCMs) incorporate less sophisticated physical schemes and provide outputs at a lower spatial resolution, but have the advantage of modeling the interaction between different components of the earth's oceans, climate, and land surface at a global scale. Improving the ability of GCMs to represent ice sheet SMB is important for making predictions of future changes in global sea level. With the ultimate goal of improving SMB simulated by the Goddard Institute for Space Studies (GISS) Model E2 GCM, we compare simulated GrIS SMB against the outputs of the MAR model and radar-derived estimates of snow accumulation. In order to reproduce present-day climate variability in the Model E2 simulation, winds are constrained to match the reanalysis datasets used to force MAR at the lateral boundaries. We conduct a preliminary assessment of the sensitivity of the simulated Model E2 SMB to surface albedo, a parameter that is known to strongly influence SMB. Model E2 albedo is set to a fixed value of 0.8 over the entire ice sheet in the initial configuration of the model (control case). We adjust this fixed value in an ensemble of simulations over a range of 0.4 to 0.8 (roughly the range of observed summer GrIS albedo values) to examine the sensitivity of ice-sheet-wide SMB to albedo. We prescribe albedo from the Moderate Resolution Imaging Spectroradiometer (MODIS) MCD43A3 v6 to examine the impact of a more realistic spatial and temporal variations in albedo. An age-dependent snow albedo parameterization is applied, and its impact on SMB relative to observations and the RCM is assessed.

  2. Realistic uncertainties on Hapke model parameters from photometric measurement

    NASA Astrophysics Data System (ADS)

    Schmidt, Frédéric; Fernando, Jennifer

    2015-11-01

    The single particle phase function describes the manner in which an average element of a granular material diffuses the light in the angular space usually with two parameters: the asymmetry parameter b describing the width of the scattering lobe and the backscattering fraction c describing the main direction of the scattering lobe. Hapke proposed a convenient and widely used analytical model to describe the spectro-photometry of granular materials. Using a compilation of the published data, Hapke (Hapke, B. [2012]. Icarus 221, 1079-1083) recently studied the relationship of b and c for natural examples and proposed the hockey stick relation (excluding b > 0.5 and c > 0.5). For the moment, there is no theoretical explanation for this relationship. One goal of this article is to study a possible bias due to the retrieval method. We expand here an innovative Bayesian inversion method in order to study into detail the uncertainties of retrieved parameters. On Emission Phase Function (EPF) data, we demonstrate that the uncertainties of the retrieved parameters follow the same hockey stick relation, suggesting that this relation is due to the fact that b and c are coupled parameters in the Hapke model instead of a natural phenomena. Nevertheless, the data used in the Hapke (Hapke, B. [2012]. Icarus 221, 1079-1083) compilation generally are full Bidirectional Reflectance Diffusion Function (BRDF) that are shown not to be subject to this artifact. Moreover, the Bayesian method is a good tool to test if the sampling geometry is sufficient to constrain the parameters (single scattering albedo, surface roughness, b, c , opposition effect). We performed sensitivity tests by mimicking various surface scattering properties and various single image-like/disk resolved image, EPF-like and BRDF-like geometric sampling conditions. The second goal of this article is to estimate the favorable geometric conditions for an accurate estimation of photometric parameters in order to provide

  3. Titan's 2 micron Surface Albedo and Haze Optical Depth in 1996-2004

    SciTech Connect

    Gibbard, S; de Pater, I; Macintosh, B; Roe, H; Max, C; Young, E; McKay, C

    2004-05-04

    We observed Titan in 1996-2004 with high-resolution 2 {micro}m speckle and adaptive optics imaging at the W.M. Keck Observatory. By observing in a 2 {micro}m broadband filter we obtain images that have contributions from both Titan's surface and atmosphere. We have modeled Titan's atmosphere using a plane-parallel radiative transfer code that has been corrected to agree with 3-D Monte Carlo predictions. We find that Titan's surface albedo ranges from {le} 0:02 in the darkest equatorial region of the trailing hemisphere to {approx_equal} 0:1 in the brightest areas of the leading hemisphere. Over the past quarter of a Saturnian year haze optical depth in Titan's Southern hemisphere has decreased substantially from a value of 0.48 in 1996 down to 0.18 in 2004, while the northern haze has been increasing over the past few years. As a result of these changes, in 2004 the North/South haze asymmetry at K' band has disappeared.

  4. Titan's 2 μm surface albedo and haze optical depth in 1996-2004

    NASA Astrophysics Data System (ADS)

    Gibbard, S. G.; de Pater, I.; Macintosh, B. A.; Roe, H. G.; Max, C. E.; Young, E. F.; McKay, C. P.

    2004-07-01

    We observed Titan in 1996-2004 with high-resolution 2 μm speckle and adaptive optics imaging at the W. M. Keck Observatory. By observing in a 2 μm broadband filter we obtain images that have contributions from both Titan's surface and atmosphere. We have modeled Titan's atmosphere using a plane-parallel radiative transfer code that has been corrected to agree with 3-D Monte Carlo predictions. We find that Titan's surface albedo ranges from <=0.02 in the darkest equatorial region of the trailing hemisphere to $\\simeq$0.1 in the brightest areas of the leading hemisphere. Over the past quarter of a Saturnian year haze optical depth in Titan's Southern hemisphere has decreased substantially from a value of 0.48 in 1996 down to 0.18 in 2004, while the northern haze has been increasing over the past few years. As a result of these changes, in 2004 the North/South haze asymmetry at K' band has disappeared.

  5. Albedo of Permanently Shadowed Regions of the Lunar Poles

    NASA Astrophysics Data System (ADS)

    Riner, M. A.; Lucey, P. G.; Bussey, B.; Cahill, J. T.; McGovern, A.

    2012-12-01

    Due to the slight tilt in the Moon's spin axis, some topographic depressions near the lunar poles experience permanent shadow and may serve as cold traps, harboring water ice and/or other volatile compounds [1]. Permanently shadowed regions (PSRs) provide an opportunity toward understanding the amount, nature and transport of volatiles on the Moon and may also be a potential resource for human exploration. While many different data sets have suggested the presence of water ice in PSRs near the lunar poles many questions remain. For example, ice does not appear to be uniformly distributed across identified PSRs. More work is needed to understand the distribution of ice in PSRs and how delivery and retention mechanisms influence the distribution. The active illumination of the Lunar Orbiter Laser Altimeter (LOLA) provides a unique contribution toward exploration PSR exploration. While LOLA is principally a laser altimeter used for quantitative topography and related cartographic and geodetic applications [2], LOLA also measures the intensity and width of the return laser pulse (1064 nm) from the surface. Here we use a global mosaic (4 pixels per degree) of LOLA albedo data corrected for instrumental drift, irregular variations, and calibrated to normal albedo using local equatorial measurements of normal albedo obtained by the Kaguya Multiband Imager [3]. Recent work using LOLA albedo shows the floor of Shackleton crater, near the lunar south pole, is brighter than the surrounding terrain (and the interior of nearby craters) at 1064 nm [4]. This albedo difference may be due to decreased space weathering due to shadowing from the Sun or to a 1 μm thick layer with 20% water ice a the surface of the crater floor [4]. Here we use LOLA dayside reflectance measurements to examine the albedo of PSRs catalogued by [5] derived from illumination modeling of a hybrid 100 m/pixel LOLA-LROC digital terrain model (DTM) up to 83° north and south latitudes. The upper latitude

  6. Effective Albedo of Vegetated Terrain at L-Band

    NASA Technical Reports Server (NTRS)

    Kurum, Mehmet; O'Neill, Peggy E.; Lang, Roger H.

    2011-01-01

    This paper derives an explicit expression for an effective albedo of vegetated terrain from the zero- and multiple- order radiative transfer (RT) model comparison. The formulation establishes a direct physical link between the effective vegetation parameterization and the theoretical description of absorption and scattering within the canopy. The paper will present an evaluation of the derived albedo for corn canopies with data taken during an experiment at Alabama A&M Winfield A. Thomas Agricultural Research Station near Huntsville, Alabama in June, 1998. The test site consisted of two 50-m x 60-m plots - one with a bare surface and the other with grass cover - and four 30-m x 50-m plots of corn at different planting densities. One corn field was planted at a full density of 9.5 plants/sq m while the others were planted at 1/3, 1/2 and 2/3 of the full density. The fields were observed with a truck-mounted L-band radiometer at incident angle of 15 degree for the period of two weeks. Soil moisture (SM) changed daily due to irrigation and natural rainfall. Variations in gravimetric SM from 18 % to 34 % were seen during this period. Ground truth data, including careful characterization of the corn size and orientation statistics, and its dielectric, was also collected and used to simulate the effective albedo for the vegetation. The single-scattering albedo is defined as the fractional power scattered from individual vegetation constituents with respect to canopy extinction. It represents single-scattering properties of vegetation elements only, and is independent of ground properties. The values of the albedo get higher when there is dense vegetation (i.e. forest, mature corn, etc.) with scatterers, such as branches and trunks (or stalks in the case of corn), which are large with respect to the wavelength. This large albedo leads to a reduction in brightness temperature in the zero-order RT solution (known as tau-omega model). Higher-order multiple-scattering RT

  7. Influence of polar-cap albedo on past and current Martian climate

    NASA Technical Reports Server (NTRS)

    Kieffer, Hugh H.; Paige, David A.

    1987-01-01

    The finding that the observed albedo of the Martian polar caps increase with increasing isolation is reviewed. Models of the Martian climate system are greatly stabilized when an insolation-dependent frost albedo instead of a constant albedo is used in the energy budget. The authors views on microphysics of the process is then presented. Long term climate models must account for the variability of CO2 frost albedo.

  8. Expected dipole asymmetry in CMB polarization

    SciTech Connect

    Namjoo, M.H.; Abolhasani, A.A.; Baghram, S.; Assadullahi, H.; Wands, D.; Firouzjahi, H. E-mail: abolhasani@ipm.ir E-mail: shant.baghramian@gmail.com E-mail: david.wands@port.ac.uk

    2015-05-01

    We explore the hemispherical asymmetry predicted in cosmic microwave background polarization when there is an asymmetry in temperature anisotropies due to primordial perturbations. We consider the cases of asymmetries due to adiabatic and isocurvature modes, and tensor perturbations. We show that the asymmetry in the TE, EE and/or BB correlations can be substantially larger than those in the TT power spectrum in certain cases. The relative asymmetry in the different cross-correlations, as well as the angular scale dependence, can in principle distinguish between different origins for the asymmetry.

  9. The electromagnetic component of albedo from superhigh energy cascades in dense media

    NASA Technical Reports Server (NTRS)

    Golynskaya, R. M.; Hein, L. A.; Plyasheshnikov, A. V.; Vorobyev, K. V.

    1985-01-01

    Albedo from cascades induced in iron by high energy gamma quanta were Monte Carlo simulated. Thereafter the albedo electromagnetic component from proton induced cascades were calculated analytically. The calculations showed that the albedo electromagnetic component increases more rapidly than the nuclear active component and will dominate at sufficiently high energies.

  10. Effect of land cover change on snow free surface albedo across the continental United States

    EPA Science Inventory

    Land cover changes (e.g., forest to grassland) affect albedo, and changes in albedo can influence radiative forcing (warming, cooling). We empirically tested albedo response to land cover change for 130 locations across the continental United States using high resolution (30 m-&t...

  11. Existence Result for the Kinetic Neutron Transport Problem with a General Albedo Boundary Condition

    NASA Astrophysics Data System (ADS)

    Sanchez, Richard; Bourhrara, Lahbib

    2011-09-01

    We present an existence result for the kinetic neutron transport equation with a general albedo boundary condition. The proof is constructive in the sense that we build a sequence that converges to the solution of the problem by iterating on the albedo term. Both nonhomogeneous and albedo boundary conditions are studied.

  12. Geometric asymmetry driven Janus micromotors.

    PubMed

    Zhao, Guanjia; Pumera, Martin

    2014-10-07

    The production and application of nano-/micromotors is of great importance. In order for the motors to work, asymmetry in their chemical composition or physical geometry must be present if no external asymmetric field is applied. In this paper, we present a "coconut" micromotor made of platinum through the partial or complete etching of the silica templates. It was shown that although both the inner and outer surfaces are made of the same material (Pt), motion of the structure can be observed as the convex surface is capable of generating oxygen bubbles. This finding shows that not only the chemical asymmetry of the micromotor, but also its geometric asymmetry can lead to fast propulsion of the motor. Moreover, a considerably higher velocity can be seen for partially etched coconut structures than the velocities of Janus or fully etched, shell-like motors. These findings will have great importance on the design of future micromotors.

  13. Line asymmetry in the Seyfert Galaxy NGC 3783

    NASA Technical Reports Server (NTRS)

    Ramirez, J. M.; Bautista, Manuel; Kallman, Timothy

    2005-01-01

    We have reanalyzed the 900 ks Chandra X-ray spectrum of NGC 3783, finding evidence on the asymmetry of the spectral absorption lines. The lines are fitted with a parametric expression that results from an analytical treatment of radiatively driven winds. The line asymmetry distribution derived from the spectrum is consistent with a non-spherical outflow with a finite optical depth. Within this scenario, our model explains the observed correlations between the line velocity shifts and the ionization parameter and between the line velocity shift and the line asymmetry. The present results may provide a framework for detailed testing of models for the dynamic and physical properties of warm absorber in Seyfert galaxies.

  14. Transverse top quark polarization and the forward-backward asymmetry

    NASA Astrophysics Data System (ADS)

    Baumgart, Matthew; Tweedie, Brock

    2013-08-01

    The forward-backward asymmetry in top pair production at the Tevatron has long been in tension with the Standard Model prediction. One of the only viable new physics scenarios capable of explaining this anomaly is an s-channel axigluon-like resonance, with the quantum numbers of the gluon but with significant axial couplings to quarks. While such a resonance can lead to a clear bump or excess in the or dijet mass spectra, it may also simply be too broad to cleanly observe. Here, we point out that broad resonances generally lead to net top and antitop polarizations transverse to the production plane. This polarization is consistent with all discrete spacetime symmetries, and, analogous to the forward-backward asymmetry itself, is absent in QCD at leading order. Within the parameter space consistent with the asymmetry measurements, the induced polarization can be sizable, and might be observable at the Tevatron or the LHC.

  15. Precise discussion of time-reversal asymmetries in B-meson decays

    DOE PAGES

    Morozumi, Takuya; Okane, Hideaki; Umeeda, Hiroyuki

    2015-02-26

    BaBar collaboration announced that they observed time reversal (T) asymmetry through B meson system. In the experiment, time dependencies of two distinctive processes, B_ →B¯0 and B¯0 → B_ (– expresses CP value) are compared with each other. In our study, we examine event number difference of these two processes. In contrast to the BaBar asymmetry, the asymmetry of events number includes the overall normalization difference for rates. Time dependence of the asymmetry is more general and it includes terms absent in one used by BaBar collaboration. Both of the BaBar asymmetry and ours are naively thought to be T-oddmore » since two processes compared are related with flipping time direction. We investigate the time reversal transformation property of our asymmetry. Using our notation, one can see that the asymmetry is not precisely a T-odd quantity, taking into account indirect CP and CPT violation of K meson systems. The effect of ϵK is extracted and gives rise to O(10–3) contribution. The introduced parameters are invariant under rephasing of quarks so that the coefficients of our asymmetry are expressed as phase convention independent quantities. Some combinations of the asymmetry enable us to extract parameters for wrong sign decays of Bd meson, CPT violation, etc. As a result, we also study the reason why the T-even terms are allowed to contribute to the asymmetry, and find that several conditions are needed for the asymmetry to be a T-odd quantity.« less

  16. Precise discussion of time-reversal asymmetries in B-meson decays

    SciTech Connect

    Morozumi, Takuya; Okane, Hideaki; Umeeda, Hiroyuki

    2015-02-26

    BaBar collaboration announced that they observed time reversal (T) asymmetry through B meson system. In the experiment, time dependencies of two distinctive processes, B_ →B¯0 and B¯0 → B_ (– expresses CP value) are compared with each other. In our study, we examine event number difference of these two processes. In contrast to the BaBar asymmetry, the asymmetry of events number includes the overall normalization difference for rates. Time dependence of the asymmetry is more general and it includes terms absent in one used by BaBar collaboration. Both of the BaBar asymmetry and ours are naively thought to be T-odd since two processes compared are related with flipping time direction. We investigate the time reversal transformation property of our asymmetry. Using our notation, one can see that the asymmetry is not precisely a T-odd quantity, taking into account indirect CP and CPT violation of K meson systems. The effect of ϵK is extracted and gives rise to O(10–3) contribution. The introduced parameters are invariant under rephasing of quarks so that the coefficients of our asymmetry are expressed as phase convention independent quantities. Some combinations of the asymmetry enable us to extract parameters for wrong sign decays of Bd meson, CPT violation, etc. As a result, we also study the reason why the T-even terms are allowed to contribute to the asymmetry, and find that several conditions are needed for the asymmetry to be a T-odd quantity.

  17. Magnetic asymmetries of unmagnetized planets

    NASA Technical Reports Server (NTRS)

    Brecht, Stephen H.

    1990-01-01

    This letter discusses the results produced by three-dimensional hybrid particle code simulations of the solar wind interaction with unmagnetized planets such as Venus and Mars. The solar wind velocity is perpendicular to the IMF in the cases studied. It is found that there are asymmetries in both the magnetic structure and shock location for spherical obstacles ranging in radius from 1000 km to 6000 km. The asymmetries found are due to differences in the electron and ion current paths (diamagnetic behavior). Mass loading of 0(+) was not included in these simulations.

  18. Challenging Postural Tasks Increase Asymmetry in Patients with Parkinson’s Disease

    PubMed Central

    Beretta, Victor Spiandor; Gobbi, Lilian Teresa Bucken; Lirani-Silva, Ellen; Simieli, Lucas; Orcioli-Silva, Diego; Barbieri, Fabio Augusto

    2015-01-01

    The unilateral predominance of Parkinson’s disease (PD) symptoms suggests that balance control could be asymmetrical during static tasks. Although studies have shown that balance control asymmetries exist in patients with PD, these analyses were performed using only simple bipedal standing tasks. Challenging postural tasks, such as unipedal or tandem standing, could exacerbate balance control asymmetries. To address this, we studied the impact of challenging standing tasks on postural control asymmetry in patients with PD. Twenty patients with PD and twenty neurologically healthy individuals (control group) participated in this study. Participants performed three 30s trials for each postural task: bipedal, tandem adapted and unipedal standing. The center of pressure parameter was calculated for both limbs in each of these conditions, and the asymmetry between limbs was assessed using the symmetric index. A significant effect of condition was observed, with unipedal standing and tandem standing showing greater asymmetry than bipedal standing for the mediolateral root mean square (RMS) and area of sway parameters, respectively. In addition, a group*condition interaction indicated that, only for patients with PD, the unipedal condition showed greater asymmetry in the mediolateral RMS and area of sway than the bipedal condition and the tandem condition showed greater asymmetry in the area of sway than the bipedal condition. Patients with PD exhibited greater asymmetry while performing tasks requiring postural control when compared to neurologically healthy individuals, especially for challenging tasks such as tandem and unipedal standing. PMID:26367032

  19. Long term surface albedo datasets generated with Meteosat images

    NASA Astrophysics Data System (ADS)

    Lattanzio, A.; Govaerts, Y. M.; Theodore, B.

    2009-04-01

    The Global Climate Observing System (GCOS) has recognized the importance and the key-role of the surface albedo in the study of the climate change. This and the other climate variables, called Essential Climate Variables (ECVs), must satisfy the following requirements: (i) a global coverage over long-term periods with adequate spatial and temporal resolution, (ii) reliability and accuracy as well as a (iii) quality control. The Coordination Group for Meteorological Satellites (CGMS) assigned to EUMETSAT an action (T18 (TF7)) in order to prototype and test a new algorithm able to retrieve surface albedo using geostationary satellites as described in the "Implementation plan for the global observing system for climate in support of the UNFCCC" document (WMO/TD No. 1219). In this frame EUMETSAT decided to develop a new specific algorithm, named Meteosat Surface Albedo (MSA), based on a method proposed by Pinty et al. The MSA algorithm is currently running in the operational reprocessing facility of EUMETSAT in order to generate reliable albedo data set starting from 1982. These data have been acquired by six different radiometers. As Meteosat first generation satellites have not been designed for climate monitoring, before proceeding with the interpretation of the complete archive (~ 25 years of data), a detailed temporal consistency analysis of the albedo data set generated with the MSA algorithm has been performed in order to check the compliance with points (ii) and (iii). Specific efforts have been put on the estimation of the measurement error accounting for the observation uncertainties and retrieval method assumptions. Currently 100% of the archive for the prime mission at 0 degree has been processed and the albedo data set can be requested from the EUMETSAT archive facility. This paper will present the method elaborated for the evaluation of the temporal consistency of the MSA data set and illustrate typical problems raising from the processing of old data and

  20. Improvement and calibration of a SSNT personal dosemeter and study of importance of albedo factor for dose calculation.

    PubMed

    Torkzadeh, F; Taheri, M

    2007-01-01

    The Neutriran albedo neutron dosemeter has been improved and calibrated for neutron personal dosimetry. The Monte Carlo code MCNP4b was used to calculate the thermal neutrons backscattered from the body (albedo factor). Backscattering from the wall, ceiling and floor in calibration room was considered also via simulation by MCNP4C. A semi automated counting system applying a high-resolution scanner was used for counting of tracks. An 241Am source was used to produce similar alpha particles from 10B (n,alpha)7Li reaction for the optimisation of scanner parameters to distinguish and separate the tracks in SSNTD, which lead to a better distinction between etched alpha tracks and, consequently, a higher linear region of dose characteristic.

  1. Measurements and Modeling of Aerosol Absorption and Single Scattering Albedo at Ambient Relative Hum

    NASA Technical Reports Server (NTRS)

    Redemann, J.; Russell, P. B.; Hamill, P.

    2000-01-01

    Uncertainties in the aerosol single scattering albedo have been identified to be an important source of errors in current large-scale model estimates of the direct aerosol radiative forcing of climate. A number of investigators have obtained estimates of the single scattering albedo from a variety of remote sensing and in situ measurements during aerosol field experiments. During the Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX, 1996) for example, estimates of the aerosol single scattering albedo were obtained (1) as a best-fit parameter in comparing radiative flux changes measured by airborne pyranometer to those computed from independently measured aerosol properties; (2) from estimates of the aerosol complex index of refraction derived using a combination of airborne sunphotometer, lidar backscatter and in situ size distribution measurements; and (3) from airborne measurements of aerosol scattering and absorption using nephelometers and absorption photometers. In this paper, we briefly compare the results of the latter two methods for two TARFOX case studies, since those techniques provide height-resolved information about the aerosol single scattering albedo. Estimates of the aerosol single scattering albedo from nephelometer and absorption photometer measurements require knowledge of the scattering and absorption humidification (i.e., the increase in these properties in response to an increase in ambient relative humidity), since both measurements are usually carried out at a relative humidity different from the ambient atmosphere. In principle, the scattering humidification factor can be measured, but there is currently no technique widely available to measure the absorption of an aerosol sample as a function of relative humidity. Frequently, for lack of better knowledge, the absorption humidification is assumed to be unity (meaning that there is no change in aerosol absorption due to an increase in ambient relative humidity). This

  2. Perspectives on asymmetry: the Erickson Lecture.

    PubMed

    Cohen, M Michael

    2012-12-01

    Topics discussed include asymmetry of the brain; prosopagnosia with asymmetric involvement; the blaspheming brain; effects of the numbers of X chromosomes on brain asymmetry; normal facial asymmetry; kissing asymmetry; left- and right-handedness; left-sided baby cradling; Nodal signaling and left/right asymmetry; primary cilium and left/right asymmetry in zebrafish; right/left asymmetry in snails; species differences in Shh and Fgf8; primary cilium in vertebrate asymmetry; Hedgehog signaling on the cilium; Wnt signaling on the cilium; situs solitus, situs inversus, and situs ambiguus (heterotaxy); ciliopathies; right-sided injuries in trilobites; unilateral ocular use in the octopus; fiddler crabs; scale-eating cichlids; narwhals; left-footed parrots; asymmetric whisker use in rats; and right-sided fatigue fractures in greyhounds.

  3. Radiative transfer in dusty nebulae. III - The effects of dust albedo

    NASA Technical Reports Server (NTRS)

    Petrosian, V.; Dana, R. A.

    1980-01-01

    The effects of an albedo of internal dust, such as ionization structure and temperature of dust grain, were studied by the quasi-diffusion method with an iterative technique for solving the radiative heat transfer equations. It was found that the generalized on-the-spot approximation solution is adequate for most astrophysical applications for a zero albedo; for a nonzero albedo, the Eddington approximation is more accurate. The albedo increases the average energy of the diffuse photons, increasing the ionization level of hydrogen and heavy elements if the Eddington approximation is applied; the dust thermal gradient is reduced so that the infrared spectrum approaches blackbody spectrum with an increasing albedo.

  4. High resolution mapping of martian neutron albedo

    NASA Astrophysics Data System (ADS)

    Sanin, A.

    It is known from data of High Energy Neutron Detector (HEND) on Mars Odyssey that there is very large regional variation of leakage flux of epithermal neutrons on the surface of Mars. The factor of regional variations is about 10 for mapping with linear resolution of about 200-300 km. Two circumpolar depressions of epithermal neutrons emission were found above latitudes of 50 - 60, which correspond to Northern and Southern permafrost regions with very high (up to 50 wt%) content of water ice. Also, according to the HEND mapping data, there are two opposite equatorial regions Arabia Terra and Memnonia, which contain about 10 wt% of water under the top layer of dry soil with a column density of about 30 g/cm2. The surface resolution of orbital data about 300 km is determined by natural collimation of neutrons in the subsurface and in the atmosphere. For a territory larger than this size, the average content of water could be estimated by the large area approximation. In this case the comparison is performed between the average counts of neutrons over the territory and predicted counts for the planet with the same model of the entire surface. The content of water is found, as the best fitting parameter of this model. For local spots of depression with much smaller sizes this procedure underestimates the content of water. Thus, according this approximation, the spot with largest depression in the Arabia Terra at 10-12 N and 30-32 E contains at least 16 wt% of water, but in reality this value could be much larger. The content of water at this spot will be obtained with better spatial resolution by so-called inverse projection procedure. This model-dependent procedure allows to test water content for areas much smaller than the size of HEND surface resolution. The results of water content according to this procedure will be presented for the Arabia spot with the greatest depression of epithermal neutrons.

  5. Abundance estimation of solid and liquid mixtures in hyperspectral imagery with albedo-based and kernel-based methods

    NASA Astrophysics Data System (ADS)

    Rand, Robert S.; Resmini, Ronald G.; Allen, David W.

    2016-09-01

    This study investigates methods for characterizing materials that are mixtures of granular solids, or mixtures of liquids, which may be linear or non-linear. Linear mixtures of materials in a scene are often the result of areal mixing, where the pixel size of a sensor is relatively large so they contain patches of different materials within them. Non-linear mixtures are likely to occur with microscopic mixtures of solids, such as mixtures of powders, or mixtures of liquids, or wherever complex scattering of light occurs. This study considers two approaches for use as generalized methods for un-mixing pixels in a scene that may be linear or non-linear. One method is based on earlier studies that indicate non-linear mixtures in reflectance space are approximately linear in albedo space. This method converts reflectance to single-scattering albedo (SSA) according to Hapke theory assuming bidirectional scattering at nadir look angles and uses a constrained linear model on the computed albedo values. The other method is motivated by the same idea, but uses a kernel that seeks to capture the linear behavior of albedo in non-linear mixtures of materials. The behavior of the kernel method can be highly dependent on the value of a parameter, gamma, which provides flexibility for the kernel method to respond to both linear and non-linear phenomena. Our study pays particular attention to this parameter for responding to linear and non-linear mixtures. Laboratory experiments on both granular solids and liquid solutions are performed with scenes of hyperspectral data.

  6. How asymmetry in animals starts

    NASA Astrophysics Data System (ADS)

    Güntürkün, Onur

    2005-10-01

    This review aims to present a speculation about mechanisms that shape the brains of humans and other animals into an asymmetrical organization. To this end, I will proceed in two steps: first, I want to recapitulate evidence from various experiments that show that some but not all asymmetries of the avian brain result from a prehatch light stimulation asymmetry. This should make it clear that avian embryos have a genetic predisposition to turn their head to the right. This results in a higher level of prehatch light stimulation of their right eye. The concomitant left-right difference in sensory input alters the brain circuits of the animal for the entire lifespan in a lateralized way. In the second part of the paper I will present evidence that some of the asymmetries of the human brain take a similar ontogenetic path as those observed in birds. This review provides the evidence that critical ontogenetic processes discovered in animal models could also be involved in the ontogeny of human cerebral asymmetries.

  7. Constraints on the diameter and albedo of 2060 Chiron

    NASA Technical Reports Server (NTRS)

    Sykes, Mark V.; Walker, Russell G.

    1991-01-01

    Asteroid 2060 Chiron is the largest known object exhibiting cometary activity. Radiometric observations made in 1983 from a ground-based telescope and the IRAS are used to examine the limits on Chiron's diameter and albedo. It is argued that Chiron's surface temperature distribution at that time is best described by an 'isothermal latitude' or 'rapid-rotator' model. Consequently, Chiron has a maximum diameter of 372 kilometers and a minimum geometric albedo of 2.7 percent. This is much bigger and darker than previous estimates, and suggests that gravity may play a significant role in the evolution of gas and dust emissions. It is also found that for large obliquities, surface temperatures can vary dramatically on time scales of a decade, and that such geometry may play a critical role in explaining Chiron's observed photometric behavior since its discovery in 1977.

  8. Deriving Albedo from Coupled MERIS and MODIS Surface Products

    NASA Technical Reports Server (NTRS)

    Gao, Feng; Schaaf, Crystal; Jin, Yu-Fang; Lucht, Wolfgang; Strahler, Alan

    2004-01-01

    MERIS Level 2 surface reflectance products are now available to the scientific community. This paper demonstrates the production of MERIS-derived surface albedo and Nadir Bidirectional Reflectance Distribution Function (BRDF) adjusted reflectances by coupling the MERIS data with MODIS BRDF products. Initial efforts rely on the specification of surface anisotropy as provided by the global MODIS BRDF product for a first guess of the shape of the BRDF and then make use all of the coincidently available, partially atmospherically corrected, cloud cleared, MERIS observations to generate MERIS-derived BRDF and surface albedo quantities for each location. Comparisons between MODIS (aerosol-corrected) and MERIS (not-yet aerosol-corrected) surface values from April and May 2003 are also presented for case studies in Spain and California as well as preliminary comparisons with field data from the Devil's Rock Surfrad/BSRN site.

  9. Land Surface Albedo from MERIS Reflectances Using MODIS Directional Factors

    NASA Technical Reports Server (NTRS)

    Schaaf, Crystal L. B.; Gao, Feng; Strahler, Alan H.

    2004-01-01

    MERIS Level 2 surface reflectance products are now available to the scientific community. This paper demonstrates the production of MERIS-derived surface albedo and Nadir Bidirectional Reflectance Distribution Function (BRDF) adjusted reflectances by coupling the MERIS data with MODIS BRDF products. Initial efforts rely on the specification of surface anisotropy as provided by the global MODIS BRDF product for a first guess of the shape of the BRDF and then make use all of the coincidently available, partially atmospherically corrected, cloud cleared, MERIS observations to generate MERIS-derived BRDF and surface albedo quantities for each location. Comparisons between MODIS (aerosol-corrected) and MERIS (not-yet aerosol-corrected) surface values from April and May 2003 are also presented for case studies in Spain and California as well as preliminary comparisons with field data from the Devil's Rock Surfrad/BSRN site.

  10. Reentrant albedo proton fluxes measured by the PAMELA experiment

    NASA Astrophysics Data System (ADS)

    Adriani, O.; Barbarino, G. C.; Bazilevskaya, G. A.; Bellotti, R.; Boezio, M.; Bogomolov, E. A.; Bongi, M.; Bonvicini, V.; Bottai, S.; Bruno, A.; Cafagna, F.; Campana, D.; Carlson, P.; Casolino, M.; Castellini, G.; Donato, C. De; De Santis, C.; De Simone, N.; Di Felice, V.; Formato, V.; Galper, A. M.; Karelin, A. V.; Koldashov, S. V.; Koldobskiy, S.; Krutkov, S. Y.; Kvashnin, A. N.; Leonov, A.; Malakhov, V.; Marcelli, L.; Martucci, M.; Mayorov, A. G.; Menn, W.; Mergé, M.; Mikhailov, V. V.; Mocchiutti, E.; Monaco, A.; Mori, N.; Munini, R.; Osteria, G.; Palma, F.; Panico, B.; Papini, P.; Pearce, M.; Picozza, P.; Ricci, M.; Ricciarini, S. B.; Sarkar, R.; Scotti, V.; Simon, M.; Sparvoli, R.; Spillantini, P.; Stozhkov, Y. I.; Vacchi, A.; Vannuccini, E.; Vasilyev, G. I.; Voronov, S. A.; Yurkin, Y. T.; Zampa, G.; Zampa, N.

    2015-05-01

    We present a precise measurement of downward going albedo proton fluxes for kinetic energy above ˜70 MeV performed by the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) experiment at an altitude between 350 and 610 km. On the basis of a trajectory tracing simulation, the analyzed protons were classified into quasi-trapped, concentrating in the magnetic equatorial region, and untrapped spreading over all latitudes, including both short-lived (precipitating) and long-lived (pseudotrapped) components. In addition, features of the penumbra region around the geomagnetic cutoff were investigated in detail. PAMELA results significantly improve the characterization of the high-energy albedo proton populations at low-Earth orbits.

  11. Exogenic and endogenic albedo and color patterns on Europa

    NASA Technical Reports Server (NTRS)

    Mcewen, A. S.

    1986-01-01

    New global and high-resolution multispectral mosaics of Europa have been produced from the Voyager imaging data. Photometric normalizations are based on multiple-image techniques that explicitly account for intrinsic albedo variations through pixel-by-pixel solutions. The exogenic color and albedo pattern on Europa is described by a second-order function of the cosine of the angular distance from the apex of orbital motion. On the basis of this second-order function and of color trends that are different on the leading and trailing hemispheres, the exogenic pattern is interpreted as being due to equilibrium between two dominant processes: (1) impact gardening and (2) magnetospheric interactions, including sulfur-ion implantation and sputtering redistribution. Removal of the model exogenic pattern in the mosaics reveals the endogenic variations, consisting of only two major units: darker (redder) and bright materials. Therefore Europa's visual spectral reflectivity is simple, having one continuous exogenic pattern and two discrete endogenic units.

  12. Control of neutron albedo in toroidal fusion reactors

    SciTech Connect

    Micklich, B.J.; Jassby, D.L.

    1983-07-01

    The MCNP and ANISN codes have been used to obtain basic neutron albedo data for materials of interest for fusion applications. Simple physical models are presented which explain albedo dependence on pre- and post-reflection variables. The angular distribution of reflected neutrons. The energy spectra of reflected neutrons are presented, and it is shown that substantial variations in the total neutron current at the outboard wall of a torus can be effected by changing materials behind the inboard wall. Analyses show that a maximum of four isolated incident-current environments may be established simultaneously on the outboard side of a torus. With suitable inboard reflectors, global tritium breeding ratios significantly larger than unity can be produced in limited-coverage breeding blankets when the effects of outboard penetrations are included.

  13. Poloidal Asymmetries in Edge Transport Barriers

    NASA Astrophysics Data System (ADS)

    Churchill, R. M.

    2014-10-01

    Investigations of the poloidal structure within edge transport barriers on Alcator C-Mod using novel impurity measurements are presented, revealing large poloidal variations of parameters within a flux surface in the H-mode pedestal region, and significantly reduced poloidal variation in L-mode or I-mode pedestals. These measurements provide complete sets of impurity density, temperature, flow velocity, and electrostatic potential at both the low- and high-field side midplane, utilizing the Gas Puff-CXRS technique. Uncertainties in magnetic equilibrium reconstructions require assumptions to be made in order to properly align the LFS/HFS profiles. In H-mode plasmas, if profiles are aligned assuming impurity temperature is constant on a flux surface, large potential asymmetries would result (eΔΦ /Te ~ 0 . 6). If instead total pressure is assumed constant on a flux-surface, then the measured potential asymmetry is significantly reduced, but large in-out asymmetries result in the impurity temperature (>1.7x). This shows that impurity temperature and potential can not both be flux functions in the pedestal region. In both alignment cases, large asymmetries in impurity density (>6x) are present in H-mode plasmas. In I-mode plasmas, which lack an electron density pedestal but do have a temperature pedestal, the poloidal variation of impurity temperature is weaker (~1.3x) and the impurity density nearly symmetric between the LFS and HFS. These measurements indicate that the sharp gradients in the pedestal region, particularly of main ion density, have a significant effect on the poloidal and radial distribution of impurities, which could have important implications for the prediction of impurity contamination in future fusion reactors such as ITER. Estimates of particle and heat transport timescales suggest that the radial and parallel transport timescales are of the same order in the pedestal region of C-Mod, supporting the idea that two-dimensional transport effects

  14. Evaluation of the Main Ceos Pseudo Calibration Sites Using Modis Brdf/albedo Products

    NASA Astrophysics Data System (ADS)

    Kharbouche, Said; Muller, Jan-Peter

    2016-06-01

    This work describes our findings about an evaluation of the stability and the consistency of twenty primary PICSs (Pseudo-Invariant Calibration Sites). We present an analysis of 13 years of 8-daily MODIS products of BRDF parameters and white-sky-albedos (WSA) over the shortwave band. This time series of WSA and BRDFs shows the variation of the "stability" varies significantly from site to site. Using a 10x10 km window size over all the sites, the change in of WSA stability is around 4% but the isotropicity, which is an important element in inter-satellite calibration, can vary from 75% to 98%. Moreover, some PICS, especially, Libya-4 which is one of the PICS which is most employed, has significant and relatively fast changes in wintertime. PICS observations of BRDF/albedo shows that the Libya-4 PICS has the best performance but it is not too far from some sites such as Libya-1 and Mali. This study also reveals that Niger-3 PICS has the longest continuous period of high stability per year, and Sudan has the most isotropic surface. These observations have important implications for the use of these sites.

  15. Effect of land cover change on snow free surface albedo across the continental United States

    NASA Astrophysics Data System (ADS)

    Wickham, J.; Nash, M. S.; Barnes, C. A.

    2016-11-01

    Land cover changes (e.g., forest to grassland) affect albedo, and changes in albedo can influence radiative forcing (warming, cooling). We empirically tested albedo response to land cover change for 130 locations across the continental United States using high resolution (30 m-×-30 m) land cover change data and moderate resolution ( 500 m-×-500 m) albedo data. The land cover change data spanned 10 years (2001 - 2011) and the albedo data included observations every eight days for 13 years (2001 - 2013). Empirical testing was based on autoregressive time series analysis of snow free albedo for verified locations of land cover change. Approximately one-third of the autoregressive analyses for woody to herbaceous or forest to shrub change classes were not significant, indicating that albedo did not change significantly as a result of land cover change at these locations. In addition, 80% of mean differences in albedo arising from land cover change were less than ± 0.02, a nominal benchmark for precision of albedo measurements that is related to significant changes in radiative forcing. Under snow free conditions, we found that land cover change does not guarantee a significant albedo response, and that the differences in mean albedo response for the majority of land cover change locations were small.

  16. Durability of high-albedo roof coatings and implications for cooling energy savings. Final report

    SciTech Connect

    Bretz, S.E.; Akbari, H.

    1994-06-01

    Twenty-six spot albedo measurements of roofs were made using a calibrated pyranometer. The roofs were surfaced with either an acrylic elastomeric coating, a polymer coating with an acrylic base, or a cementitious coating. Some of the roofs` albedos were measured before and after washing to determine whether the albedo decrease was permanent. Data indicated that most of the albedo degradation occurred within the first year, and even within the first two months. On one roof, 70% of one year`s albedo degradation occurred in the first two months. After the first year, the degradation slowed, with data indicating small losses in albedo after the second year. Measurements of seasonal cooling energy savings by Akbari et al. (1993) included the effects of over two months of albedo degradation. We estimated {approximately}20% loss in cooling-energy savings after the first year because of dirt accumulation. For most of the roofs we cleaned, the albedo was restored to within 90% of its initial value. Although washing is effective at restoring albedo, the increase in energy savings is temporary and labor costs are significant in comparison to savings. By our calculations, it is not cost-effective to hire someone to clean a high-albedo roof only to achieve energy savings. Thus, it would be useful to develop and identify dirt-resistant high-albedo coatings.

  17. Effect of land cover change on snow free surface albedo across the continental United States

    USGS Publications Warehouse

    Wickham, J.; Nash, M.S.; Barnes, Christopher A.

    2016-01-01

    Land cover changes (e.g., forest to grassland) affect albedo, and changes in albedo can influence radiative forcing (warming, cooling). We empirically tested albedo response to land cover change for 130 locations across the continental United States using high resolution (30 m-×-30 m) land cover change data and moderate resolution (~ 500 m-×-500 m) albedo data. The land cover change data spanned 10 years (2001 − 2011) and the albedo data included observations every eight days for 13 years (2001 − 2013). Empirical testing was based on autoregressive time series analysis of snow free albedo for verified locations of land cover change. Approximately one-third of the autoregressive analyses for woody to herbaceous or forest to shrub change classes were not significant, indicating that albedo did not change significantly as a result of land cover change at these locations. In addition, ~ 80% of mean differences in albedo arising from land cover change were less than ± 0.02, a nominal benchmark for precision of albedo measurements that is related to significant changes in radiative forcing. Under snow free conditions, we found that land cover change does not guarantee a significant albedo response, and that the differences in mean albedo response for the majority of land cover change locations were small.

  18. Determining Small Scale Albedos Using High Resolution Multiangle Satellite Measurements

    NASA Astrophysics Data System (ADS)

    Markowski, G. R.; Davies, R.

    2005-05-01

    Current satellite short-wave (SW) albedo measurements, such as CERES's, have only a broad spatial resolution and cannot by themselves accurately measure reflectance (roughly solar "forcing") on small space and time scales. The major difficulty is that earth's surface reflectivity, including the atmosphere and clouds, is substantially anisotropic. However, accurate regional and time-dependent albedos are needed for studying causes of climate variability and change, and improving models from global to at least cloud resolving scales. A first step to obtain these albedos, for which we show results, is to accurately relate (and verify) the high resolution spatial and angular surface narrow-band MISR (Multi-Angle Imaging Spectroradiometer) radiance measurements aboard the Terra satellite to coincident total shortwave broadband (SWB) low resolution measurements from the onboard CERES instrument. Because MISR measures radiance of the same points along an orbital swath, it becomes possible to check and improve Angular (reflection) Distribution Models (ADMs) at small scales (< 1 km). The ADMs can later be used to invert a measured angular radiance to a local albedo. The difficulty lies in obtaining accurate ADMs for earth's highly varied surface and lighting conditions. We show prediction accuracy examples of CERES SWB vs. single and multiple band MISR data regressions. We include view angle dependence (9 angles: nadir plus 26, 46, 60, and 70 degrees fore and aft) and show improved accuracy when surface data, e.g., solar zenith and scattering angle, and surface type are included. In many cases, we predict angular (bidirectional) reflectance to ~ 0.01, or about 10 watts/sq m in irradiance. We also show examples of "difficult" scene types, such as varying levels of broken clouds, where accuracy degrades by a factor of ~2.

  19. Extended HXR Sources - Albedo Patches or Coronal Sources

    NASA Technical Reports Server (NTRS)

    Dennis, Brian R.

    2011-01-01

    Extended HXR sources in the presence of compact footpoints have been reported based on visibility amplitudes from different detectors. Attempts have been made to determine the location and extent of these sources through direct imaging. Results of this work will be described for simulated sources and for specific flares at different solar longitudes, with a discussion of the possible nature of the extended sources as either albedo patches or coronal sources or a combination of the two.

  20. Signatures of Volatiles in the Lunar Proton Albedo

    NASA Technical Reports Server (NTRS)

    Schwadron, N. A.; Wilson, J. K.; Looper, M. D.; Jordan, A. P.; Spence, H. E.; Blake, J. B.; Case, A. W.; Iwata, Y.; Kasper, J. C.; Farrell, W. M.; Petro, N.

    2015-01-01

    We find evidence for hydrated material in the lunar regolith using "albedo protons" measured with the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on the Lunar Reconnaissance Orbiter (LRO). Fluxes of these albedo protons, which are emitted from the regolith due to steady bombardment by high energy radiation (Galactic Cosmic Rays), are observed to peak near the poles, and are inconsistent with the latitude trends of heavy element enrichment (e.g., enhanced Fe abundance). The latitudinal distribution of albedo protons anti-correlates with that of epithermal or high energy neutrons. The high latitude enhancement may be due to the conversion of upward directed secondary neutrons from the lunar regolith into tertiary protons due to neutron-proton collisions in hydrated regolith that is more prevalent near the poles. The CRaTER instrument may thus provide important measurements of volatile distributions within regolith at the Moon and potentially, with similar sensors and observations, at other bodies within the Solar System.

  1. Gamma-ray Albedo of Small Solar System Bodies

    SciTech Connect

    Moskalenko, I.V.

    2008-03-25

    We calculate the {gamma}-ray albedo flux from cosmic-ray (CR) interactions with the solid rock and ice in Main Belt asteroids and Kuiper Belt objects (KBOs) using the Moon as a template. We show that the {gamma}-ray albedo for the Main Belt and KBOs strongly depends on the small-body mass spectrum of each system and may be detectable by the forthcoming Gamma Ray Large Area Space Telescope (GLAST). If detected, it can be used to derive the mass spectrum of small bodies in the Main Belt and Kuiper Belt and to probe the spectrum of CR nuclei at close-to-interstellar conditions. The orbits of the Main Belt asteroids and KBOs are distributed near the ecliptic, which passes through the Galactic center and high Galactic latitudes. Therefore, the {gamma}-ray emission by the Main Belt and Kuiper Belt has to be taken into account when analyzing weak {gamma}-ray sources close to the ecliptic. The asteroid albedo spectrum also exhibits a 511 keV line due to secondary positrons annihilating in the rock. This may be an important and previously unrecognized celestial foreground for the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) observations of the Galactic 511 keV line emission including the direction of the Galactic center. For details of our calculations and references see [1].

  2. Supercritical Salt Spray for the Implementation of Cloud Albedo Modification

    NASA Astrophysics Data System (ADS)

    Neukermans, A. P.; Cooper, G.; Foster, J. D.; Galbraith, L.; Ormond, B.; Wang, Q.; Johnston, D.; Cloud Brightening Research

    2011-12-01

    Of all the geo-engineering schemes proposed so far, the Latham-Salter cloud albedo modification scheme is perhaps the most benign and "natural" method. In its full deployment, it proposes to densify and thereby modify the albedo of low-hanging marine boundary clouds by a few percent such that the overall earth albedo might be changed by 1%. The scheme would require the production of vast numbers of salt cloud condensation nuclei (CCN), in one implementation on the order of 10^17 per second from each of some 1500 autonomous sailing vessels. We have investigated a number of possible techniques to create these nuclei. We reported previously the laboratory production of suitable nuclei from saltwater using Taylor cones. This method would require about 10^8 Taylor cones per vessel to get to the required CCN production rate, and hence needs a very extensive scale-up effort. We report here on the use of saltwater sprayed at or near its critical temperature and pressure through small nozzles. Although a number of technical problems remain, results to date suggest that this method might be suitable, at least for research purposes. The mean particle size distributions of nuclei generated (40-100 nm) are acceptable, and the scale-up effort to the estimated number of nozzles required (1000-2000) seems reasonable.

  3. Signatures of volatiles in the lunar proton albedo

    NASA Astrophysics Data System (ADS)

    Schwadron, N. A.; Wilson, J. K.; Looper, M. D.; Jordan, A. P.; Spence, H. E.; Blake, J. B.; Case, A. W.; Iwata, Y.; Kasper, J. C.; Farrell, W. M.; Lawrence, D. J.; Livadiotis, G.; Mazur, J.; Petro, N.; Pieters, C.; Robinson, M. S.; Smith, S.; Townsend, L. W.; Zeitlin, C.

    2016-07-01

    We find evidence for hydrated material in the lunar regolith using "albedo protons" measured with the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on the Lunar Reconnaissance Orbiter (LRO). Fluxes of these albedo protons, which are emitted from the regolith due to steady bombardment by high energy radiation (Galactic Cosmic Rays), are observed to peak near the poles, and are inconsistent with the latitude trends of heavy element enrichment (e.g., enhanced Fe abundance). The latitudinal distribution of albedo protons anti-correlates with that of epithermal or high energy neutrons. The high latitude enhancement may be due to the conversion of upward directed secondary neutrons from the lunar regolith into tertiary protons due to neutron-proton collisions in hydrated regolith that is more prevalent near the poles. The CRaTER instrument may thus provide important measurements of volatile distributions within regolith at the Moon and potentially, with similar sensors and observations, at other bodies within the Solar System.

  4. Dim waters: side effects of geoengineering using ocean albedo modification

    NASA Astrophysics Data System (ADS)

    Piskozub, J.; Neumann, T.

    2012-04-01

    We use a Monte Carlo radiative transfer code to check how the recently proposed geoengineering by injection of clean or coated microbubbles into the ocean mixed layer would impact in-water light fields. We show that due to massive multiscattering inside a bubble cloud, coating the bubbles with surfactant, needed to stabilize them, would not increase their albedo change effectiveness as much as expected basing on their backscattering coefficients. However, the bubble effect on reflectance is larger than estimated previously using a discrete ordinate method of solving the radiative transfer problem. We show significant side effects of ocean albedo change needed to counter global warming expected in this century and beyond (reduction of euphotic zone depth by respectively 20% and 50% in the case of global ocean albedo change corresponding to -1.25 K and -6 K global surface temperature change and irradiance decrease at 10 m depth by respectively 40% and over 80%) even if all ocean surface was "brightened". We discuss the possible negative side effect of such in-water light dimming on marine life. We conclude that the proposed "ocean brightening" is in fact "ocean dimming" as concerns the marine environment, on a scale that in any other circumstances would be called catastrophic. Finally, we briefly discuss other possible side effect of making the surface ocean waters turbid (both optically and acoustically), of adding large amounts of surfactants to the surface ocean layers and of surface cooling of the ocean, especially within the tropics.

  5. Possible Albedo Proton Signature of Hydrated Lunar Surface Layer

    NASA Astrophysics Data System (ADS)

    Schwadron, N.; Wilson, J. K.; Looper, M. D.; Jordan, A.; Spence, H. E.; Blake, J. B.; Case, A. W.; Iwata, Y.; Kasper, J. C.; Farrell, W. M.; Lawrence, D. J.; Livadiotis, G.; Mazur, J. E.; Petro, N. E.; Pieters, C. M.; Robinson, M. S.; Smith, S. S.; Townsend, L. W.; Zeitlin, C. J.

    2015-12-01

    We find evidence for a surface layer of hydrated material in the lunar regolith using "albedo protons" measured by the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on the Lunar Reconnaissance Orbiter (LRO). Fluxes of these albedo protons, which are emitted from the regolith due to steady bombardment by high-energy radiation (Galactic Cosmic Rays), are observed to peak near the poles, and cannot be accounted for by either heavy element enrichment (e.g., enhanced Fe abundance), or by deeply buried (> 50 cm) hydrogenous material. The latitudinal distribution of albedo protons does not correlate with that of epithermal or high-energy neutrons. The high latitude enhancement may be due to the conversion of upward directed secondary neutrons from the lunar regolith into tertiary protons due to neutron-proton collisions in a thin (~ 1-10 cm) layer of hydrated regolith near the surface that is more prevalent near the poles. The CRaTER instrument thus provides critical measurements of volatile distributions within lunar regolith and potentially, with similar sensors and observations, at other bodies within the Solar System.

  6. On the Non-Monotonic Variation of the Opposition Surge Morphology with Albedo Exhibited by Satellites' Surface

    NASA Technical Reports Server (NTRS)

    Deau, E. A.; Spilker, L. J.; Flandes, A.

    2011-01-01

    We used well know phase functions of satellites and rings around the giant planets of our Solar System to study the morphology of the opposition effect (at phase angles alpha < 20 degrees. To avoid the effect of the variable finite size of the Sun, we use a deconvolution morphological model to retrieve the morphological parameters of the surge (A and HWHM). These parameters are found to have a non-monotonic variation with the single scattering albedo, similar to that observed in asteroids, which is unexplained so far. The non-monotonic variation is discussed in the framework of the coherent backscattering and shadow hiding mechanisms.

  7. On the Origin of System III Asymmetries in the Io Torus

    NASA Technical Reports Server (NTRS)

    Schneider, N. M.; Delamere, P. A.

    2006-01-01

    The Io plasma torus exhibits several intriguing asymmetries which offer insights to the processes that transport mass and energy through the system. While these asymmetries are increasingly well described observationally, most still lack physical explanations. One important asymmetry is fixed in the coordinate system corotating with Jupiter's magnetic field. Space-based and ground-based observations have shown that torus ions are hotter and more highly ionized around System III 20 deg. Our simulations show that this type of torus asymmetry can be caused by enhanced pickup of fresh ions from Io's neutral clouds near these longitudes. The enhancement is caused primarily by the tilt and offset of the torus relative to the neutral clouds. We will report on the model parameters required to match the observed asymmetries, and offer predictions which will allow a test of this hypothesis.

  8. Measurement of Z0 lepton coupling asymmetries

    SciTech Connect

    Smy, Michael Burghard

    1997-07-01

    Polarized Z0`s from e+e- collisions at the SLAC Linear Collider (SLC) have been used to determine the asymmetry parameters Ae, Aμ and Aτ from the leptonic decay channels. This is the first direct measurement of Aμ. The data have been gathered by the SLC Large Detector (SLD) with the electron polarization averaging 63% during the 1993 data taking period and 77% in 1994-95. A maximum likelihood procedure as well as cross section asymmetries was used to measure the asymmetry parameters from the differential cross sections for equal luminosities of left- and right-handed electron beams. The polarization-dependent muon-pair distributions give Aμ = 0.102 ±0.034 and the tau-pairs give Aτ = 0.195 ±0.034. The initial state electronic couplings in all three leptonic channels as well as the final state angular distribution in the e+e- final state measure Ae to be Ae = 0.152±0.012. Assuming lepton universality and defining a global leptonic asymmetry parameter Ae-μ-τ = 0.151±0.011. This global leptonic asymmetry value translates directly into sin2θWeff=0.2310v0.0014 at the Z0 pole.

  9. Multidecadal analysis of forest growth and albedo in boreal Finland

    NASA Astrophysics Data System (ADS)

    Lukeš, Petr; Stenberg, Pauline; Mõttus, Matti; Manninen, Terhikki; Rautiainen, Miina

    2016-10-01

    It is well known that forests serve as carbon sinks. However, the balancing effect of afforestation and increased forest density on global warming due to carbon storage may be lost by low albedo (thus high absorption) of the forests. In the last 30 years, there has been a steady increase in the growing stock of Finnish forests by nearly a quarter while the area of the forests has remained virtually unchanged. Such increase in forest density together with the availability of detailed forest inventories provided by the Multi-Source National Forest Inventory (MS-NFI) in high spatial resolution makes Finland an ideal candidate for exploring the effects of increased forest density on satellite derived estimates of bio-geochemical products e.g. albedo (directional-hemispherical reflectance, DHR), fraction of photosynthetically active radiation absorbed by canopies (fAPAR), leaf area index (LAI) and normalized difference vegetation index (NDVI) in both current and long-term perspective. In this study, we first used MODIS-based vegetation satellite products for Finnish forests to study their seasonal patterns and interrelations. Next, the peak growing season observations are linked to the MS-NFI database to yield the generic relationships between forest density and the satellite-derived vegetation indicators. Finally, long-term GIMMS3g datasets between 1982 and 2011 (2008 for DHR) are analyzed and interpreted using forest inventory data. The vegetation peak growing season NIR DHR and VIS DHR showed weak to moderate negative correlation with fAPAR, whereas there was no correlation between NIR DHR and fAPAR. Next, we show that the spectral albedos in the near-infrared region (NIR DHR) showed weak negative correlation with forest biomass, basal area or canopy cover whereas, as expected, the spectral albedo in the visible region (VIS DHR) correlated negatively with these measures of forest density. Interestingly, the increase in forest density (biomass per ha) of Finnish

  10. Volumetric assessment of cerebral asymmetries in dogs.

    PubMed

    Siniscalchi, Marcello; Franchini, Delia; Pepe, Anna M; Sasso, Raffaella; Dimatteo, Salvatore; Vallortigara, Giorgio; Quaranta, Angelo

    2011-09-01

    In the present study we quantified volumetric brain asymmetries from computed tomography (CT) scans in 12 healthy dogs, using a semi-automated technique for assessing in vivo structure asymmetry. Volumetric assessment of asymmetrical cerebral lateral ventricle (ALV) was also investigated. Our results showed that seven dogs exhibited a right hemisphere significantly greater than the left, two dogs had a left-greater-than-right hemisphere asymmetry, and finally two dogs displayed no significant brain volumetric asymmetry. This right-biased hemispheric asymmetry supports data reported previously using post-mortem morphological studies in both dogs and other mammalian species.

  11. Assessing the measurement of aerosol single scattering albedo by Cavity Attenuated Phase-Shift Single Scattering Monitor (CAPS PMssa)

    NASA Astrophysics Data System (ADS)

    Perim de Faria, Julia; Bundke, Ulrich; Onasch, Timothy B.; Freedman, Andrew; Petzold, Andreas

    2016-04-01

    The necessity to quantify the direct impact of aerosol particles on climate forcing is already well known; assessing this impact requires continuous and systematic measurements of the aerosol optical properties. Two of the main parameters that need to be accurately measured are the aerosol optical depth and single scattering albedo (SSA, defined as the ratio of particulate scattering to extinction). The measurement of single scattering albedo commonly involves the measurement of two optical parameters, the scattering and the absorption coefficients. Although there are well established technologies to measure both of these parameters, the use of two separate instruments with different principles and uncertainties represents potential sources of significant errors and biases. Based on the recently developed cavity attenuated phase shift particle extinction monitor (CAPS PM_{ex) instrument, the CAPS PM_{ssa instrument combines the CAPS technology to measure particle extinction with an integrating sphere capable of simultaneously measuring the scattering coefficient of the same sample. The scattering channel is calibrated to the extinction channel, such that the accuracy of the single scattering albedo measurement is only a function of the accuracy of the extinction measurement and the nephelometer truncation losses. This gives the instrument an accurate and direct measurement of the single scattering albedo. In this study, we assess the measurements of both the extinction and scattering channels of the CAPS PM_{ssa through intercomparisons with Mie theory, as a fundamental comparison, and with proven technologies, such as integrating nephelometers and filter-based absorption monitors. For comparison, we use two nephelometers, a TSI 3563 and an Aurora 4000, and two measurements of the absorption coefficient, using a Particulate Soot Absorption Photometer (PSAP) and a Multi Angle Absorption Photometer (MAAP). We also assess the indirect absorption coefficient

  12. Geometric asymmetry driven Janus micromotors

    NASA Astrophysics Data System (ADS)

    Zhao, Guanjia; Pumera, Martin

    2014-09-01

    The production and application of nano-/micromotors is of great importance. In order for the motors to work, asymmetry in their chemical composition or physical geometry must be present if no external asymmetric field is applied. In this paper, we present a ``coconut'' micromotor made of platinum through the partial or complete etching of the silica templates. It was shown that although both the inner and outer surfaces are made of the same material (Pt), motion of the structure can be observed as the convex surface is capable of generating oxygen bubbles. This finding shows that not only the chemical asymmetry of the micromotor, but also its geometric asymmetry can lead to fast propulsion of the motor. Moreover, a considerably higher velocity can be seen for partially etched coconut structures than the velocities of Janus or fully etched, shell-like motors. These findings will have great importance on the design of future micromotors.The production and application of nano-/micromotors is of great importance. In order for the motors to work, asymmetry in their chemical composition or physical geometry must be present if no external asymmetric field is applied. In this paper, we present a ``coconut'' micromotor made of platinum through the partial or complete etching of the silica templates. It was shown that although both the inner and outer surfaces are made of the same material (Pt), motion of the structure can be observed as the convex surface is capable of generating oxygen bubbles. This finding shows that not only the chemical asymmetry of the micromotor, but also its geometric asymmetry can lead to fast propulsion of the motor. Moreover, a considerably higher velocity can be seen for partially etched coconut structures than the velocities of Janus or fully etched, shell-like motors. These findings will have great importance on the design of future micromotors. Electronic supplementary information (ESI) available: Additional SEM images, data analysis, Videos S

  13. Searching for Correlation Between Neutron Albedo and Near-IR Albedo of Mars Surface Using HEND/Odyssey and MOLA/MGS Data

    NASA Astrophysics Data System (ADS)

    Demidov, N. E.; Boynton, W. V.; Gilichinsky, D. A.; Litvak, M. L.; Kozyrev, A. S.; Mitrofanov, I. G.; Sanin, A. B.; Saunders, R. S.; Smith, D. E.; Tretykov, V. I.; Zuber, M. T.

    2007-03-01

    Strong negative correlation between HEND neutron albedo and MOLA near-IR albedo is found within two broad latitude belts: 40°N-80°N and 40°S-60°S. Interpretation: water ice in these belts is buried below the dry skin layer, which thickness is determined

  14. Developmental Changes in Topological Asymmetry Between Hemispheric Brain White Matter Networks from Adolescence to Young Adulthood.

    PubMed

    Zhong, Suyu; He, Yong; Shu, Hua; Gong, Gaolang

    2016-04-24

    Human brain asymmetries have been well described. Intriguingly, a number of asymmetries in brain phenotypes have been shown to change throughout the lifespan. Recent studies have revealed topological asymmetries between hemispheric white matter networks in the human brain. However, it remains unknown whether and how these topological asymmetries evolve from adolescence to young adulthood, a critical period that constitutes the second peak of human brain and cognitive development. To address this question, the present study included a large cohort of healthy adolescents and young adults. Diffusion and structural magnetic resonance imaging were acquired to construct hemispheric white matter networks, and graph-theory was applied to quantify topological parameters of the hemispheric networks. In both adolescents and young adults, rightward asymmetry in both global and local network efficiencies was consistently observed between the 2 hemispheres, but the degree of the asymmetry was significantly decreased in young adults. At the nodal level, the young adults exhibited less rightward asymmetry of nodal efficiency mainly around the parasylvian area, posterior tempo-parietal cortex, and fusiform gyrus. These developmental patterns of network asymmetry provide novel insight into the human brain structural development from adolescence to young adulthood and also likely relate to the maturation of language and social cognition that takes place during this period.

  15. Z Boson Asymmetry Measurements at the Tevatron

    SciTech Connect

    Quinn, B.

    2014-01-01

    We present measurements of the forward-backward asymmetry (A_fb) in dilepton pair decays of Z bosons produced in ppbar collisions using the full Tevatron dataset. The CDF experiment extracts a value for the effective weak mixing angle parameter sin^{2}\\theta^{l}_{eff} of 0.2315 +/- 0.0010 from the A_fb distribution of dimuon events in 9.2 fb^{-1} of integrated luminosity. From dielectron events in 9.7 fb^{-1} of data, the D0 experiment finds sin^{2}\\theta^{l}_{eff} = 0.23106 +/- 0.00053, the world's most precise measurement of sin^{2}\\theta^{l}_{eff} from hadron colliders and with light quark couplings.

  16. Hemispheric asymmetry in martian seasonal surface water ice from MGS TES

    NASA Astrophysics Data System (ADS)

    Bapst, Jonathan; Bandfield, Joshua L.; Wood, Stephen E.

    2015-11-01

    The Mars Global Surveyor (MGS) Thermal Emission Spectrometer (TES) visible/near-infrared and thermal infrared bolometers measured planetary broadband albedo and temperature for more than three Mars years. As seasons progress on Mars, surface temperatures may fall below the frost point of volatiles in the atmosphere (namely, carbon dioxide and water). Systematic mapping of the spatial and temporal occurrence of these volatiles in the martian atmosphere, on the surface, and in the subsurface has shown their importance in understanding the climate of Mars. We examine TES daytime albedo, temperature, and atmospheric opacity data to map the latitudinal and temporal occurrence of seasonal surface water frost on Mars. We expand on previous work by looking at the behavior of water frost over the entire martian year, made possible with comprehensive, multi-year data. Interpretations of frost are based on albedo changes and the corresponding daytime temperature range. Data is considered consistent with water frost when there are significant albedo increases (>0.05 relative to frost-free seasons) and the observed temperatures are ∼170-200 K. We argue the presence of extensive water frost in the northern hemisphere, extending from the pole to ∼40°N, following seasonal temperature trends. In the north, water frost first appears near the pole at Ls = ∼160° and is last observed at Ls = ∼90°. Extensive water frost is less evident in southern hemisphere data, though both hemispheres show data that are consistent with the presence of a water ice annulus during seasonal cap retreat. Hemispherical asymmetry in the occurrence of seasonal water frost is due in part to the lower (∼40%) atmospheric water vapor abundances observed in the southern hemisphere. Our results are consistent with net transport of water vapor to the northern hemisphere. The deposition and sublimation of seasonal water frost may significantly increase the near-surface water vapor density that could

  17. Assessment of VIIRS daily BRDF/Albedo product using in situ measurement of SURFRAD sites and MODIS V006 daily BRDF/Albedo product

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Wang, Z.; Sun, Q.; Schaaf, C.; Roman, M. O.

    2014-12-01

    Surface albedo is defined as the ratio of upwelling to downwelling radiative flux. It's important for understanding the global energy budget. Remote sensing albedo products provide global time continuous coverage to help capture global energy variability and change. The Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi-NPP satellite, launched on October 28, 2011, is aiming to provide continues data record with the MODerate resolution Imaging Spectroradiometer (MODIS), which has been providing Bidirectional Reflectance Distribution Function (BRDF)/Albedo product since 2000. By utilizing the same approach that was used for the most recently V006 daily MODIS BRDF/Albedo product, VIIRS has the ability to keep providing products for research and operational users. Validating albedo product of VIIRS using in situmeasured albedo can assure the quality for land surface climate and biosphere models, and comparing with MODIS product can assure time continues of BRDF/albedo product. The daily BRDF/Albedo product still uses 16-day period multispectral, cloud-cleared, atmospherically-corrected surface reflectances to fit the Ross-Thick/Li-Sparse-Reciprocal semi-empirical BRDF model. But the multiday observations are also weighted based on proximity to the production date in order to emphasis on that individual day. Surface Radiation Budget Network (SURFRAD) was established in 1993 through the support of NOAA's Office of Global Programs. In situ albedo was driven from downwelling and upwelling radiative flux measured from the towers. Fraction of diffuse sky light was calculated using the direct and diffuse solar recorded in the data. It was further used to translate VIIRS, MODIS black sky and white sky albedos into actual albedo at local solar noon. Results show that VIIRS, MODIS and in situ albedo agree well at SURFARD spatially representative sites. While the VIIRS surface reflectance, snow, and cloud algorithms are still undergoing revision, the result shows that

  18. A Study of Libration Points in Modified CR3BP Under Albedo Effect when Smaller Primary is an Ellipsoid

    NASA Astrophysics Data System (ADS)

    Idrisi, M. Javed

    2017-03-01

    As we know that the Sun is a source of radiation in our solar system, the other planets or asteroids absorb some of the radiations incident on it and some reflected back into the space, these reflected radiations are called Albedo. The spacecraft is affected by both radiations i.e direct radiations as well as albedo. In this paper this is investigated how albedo perturbed the libration points and its stability in restricted three-body problem when less massive primary is an ellipsoid? It is found that there exist five libration points, three collinear and two non-collinear, the non-collinear libration points are stable for a critical value of mass parameter μ≤μ c , where μ c= 0.0385208965 …- (0.00891747 + 0.222579k) α- 0.02206859 σ 1 - 0.04071097 σ 2 but collinear libration points are still unstable. Also, an example of Sun-Earth system is taken in the last as a real application.

  19. Global retrieval of bidirectional reflectance and albedo over land from EOS MODIS and MISR data: Theory and algorithm

    NASA Astrophysics Data System (ADS)

    Wanner, W.; Strahler, A. H.; Hu, B.; Lewis, P.; Muller, J.-P.; Li, X.; Schaaf, C. L. Barker; Barnsley, M. J.

    1997-07-01

    This paper describes the theory and the algorithm to be used in producing a global bidirectional reflectance distribution function (BRDF) and albedo product from data to be acquired by the moderate resolution imaging spectroradiometer (MODIS) and the multiangle imaging spectroradiometer (MISR), both to be launched in 1998 on the AM-1 satellite platform as part of NASA's Earth Observing System (EOS). The product will be derived using the kernel-driven semiempirical Ambrals BRDF model, utilizing five variants of kernel functions characterizing isotropic, volume and surface scattering. The BRDF and the albedo of each pixel of the land surface will be modeled at a spatial resolution of 1 km and once every 16 days in seven spectral bands spanning the visible and the near infrared. The BRDF parameters retrieved and recorded in the MODIS BRDF/albedo product will be intrinsic surface properties decoupled from the prevailing atmospheric state and hence suited for a wide range of applications requiring characterization of the directional anisotropy of Earth surface reflectance. A set of quality control flags accompanies the product. An initial validation of the Ambrals model is demonstrated using a variety of field-measured data sets for several different land cover types.

  20. Quantifying the Impacts of Surface Albedo on Climate Using the WRF Model

    NASA Astrophysics Data System (ADS)

    Schlosser, C. A.; Xu, L.; Xu, X.; Gregory, J.; Kirchain, R.

    2015-12-01

    Surface albedo is an important part of the energy budget in shaping local and regional climate. It could also be a potential tool to mitigate the anthropogenic effect on climate change. However, the current level of scientific understanding of surface albedo on global warming potential is medium to low. In order to investigate the anthropogenic impact of surface albedo on climate, different scenarios of urban surface albedo over continental US using the WRF model are simulated. In this study, the change in surface albedo applies to rooftops, pavements, and walls of urban land cover grid cells. The two groups of simulations (low and high albedo) were compared to determine the impacts of elevating urban surface albedo and to account for the uncertainty in the errors or noise introduced by the slightly different initial conditions. The results are represented as the differences in surface temperature and the top of the atmosphere radiation between the two scenarios when urban surface albedos are elevated from 0.15 to 0.40. The ensemble mean of all potential outcomes as a whole, instead of individual initial conditions, shows that the impact of elevating surface albedo has a cooling effect that is robust at both local and regional scales during the summer season. More refined analyses of urban areas will provide insights on surface albedo impacts in specific regions. Future analyses may address changes in CO2 equivalence.

  1. Assessment of Greenland albedo variability from the advanced very high resolution radiometer Polar Pathfinder data set

    NASA Astrophysics Data System (ADS)

    Stroeve, Julienne

    2001-12-01

    The advanced very high resolution radiometer Polar Pathfinder (APP) data set is used to examine the variability of the surface albedo over Greenland. Analysis of the APP albedo record from 1981 to 1998 show anomalously low albedo during 1995 and 1998 over most of the ice sheet as compared with the other years. The low albedo encountered during these years suggests that the ice sheet experienced considerable melt in 1995 and 1998, particularly near the western margin of the ice sheet. Conversely, anomalously high albedos were found in 1992 as a result of colder temperatures and hence less melt following the eruption of Mount Pinatubo. The relationship between the annual North Atlantic Oscillation (NAO) index and the mean summer albedo from all the stations reveals a positive correlation of 0.44 and a positive correlation of 0.55 for the southern part of the ice sheet. Therefore variations in the mean summer albedo over Greenland can, in part, be explained by variations in the NAO such that during periods of intensification of the normal mode of the NAO the mean summer albedo is above normal. Trend analysis reveals an overall downward trend in surface albedo from 1981 to 1998, which agrees with recent trends in melt and precipitation. However, the trend was found not to be statistically significant but rather influenced by the low albedo in recent years.

  2. Robust estimation of albedo for illumination-invariant matching and shape recovery.

    PubMed

    Biswas, Soma; Aggarwal, Gaurav; Chellappa, Rama

    2009-05-01

    We present a nonstationary stochastic filtering framework for the task of albedo estimation from a single image. There are several approaches in the literature for albedo estimation, but few include the errors in estimates of surface normals and light source direction to improve the albedo estimate. The proposed approach effectively utilizes the error statistics of surface normals and illumination direction for robust estimation of albedo, for images illuminated by single and multiple light sources. The albedo estimate obtained is subsequently used to generate albedo-free normalized images for recovering the shape of an object. Traditional Shape-from-Shading (SFS) approaches often assume constant/piecewise constant albedo and known light source direction to recover the underlying shape. Using the estimated albedo, the general problem of estimating the shape of an object with varying albedo map and unknown illumination source is reduced to one that can be handled by traditional SFS approaches. Experimental results are provided to show the effectiveness of the approach and its application to illumination-invariant matching and shape recovery. The estimated albedo maps are compared with the ground truth. The maps are used as illumination-invariant signatures for the task of face recognition across illumination variations. The recognition results obtained compare well with the current state-of-the-art approaches. Impressive shape recovery results are obtained using images downloaded from the Web with little control over imaging conditions. The recovered shapes are also used to synthesize novel views under novel illumination conditions.

  3. "TNOs are Cool": A survey of the trans-Neptunian region. IV. Size/albedo characterization of 15 scattered disk and detached objects observed with Herschel-PACS

    NASA Astrophysics Data System (ADS)

    Santos-Sanz, P.; Lellouch, E.; Fornasier, S.; Kiss, C.; Pal, A.; Müller, T. G.; Vilenius, E.; Stansberry, J.; Mommert, M.; Delsanti, A.; Mueller, M.; Peixinho, N.; Henry, F.; Ortiz, J. L.; Thirouin, A.; Protopapa, S.; Duffard, R.; Szalai, N.; Lim, T.; Ejeta, C.; Hartogh, P.; Harris, A. W.; Rengel, M.

    2012-05-01

    Context. Physical characterization of trans-Neptunian objects, a primitive population of the outer solar system, may provide constraints on their formation and evolution. Aims: The goal of this work is to characterize a set of 15 scattered disk (SDOs) and detached objects, in terms of their size, albedo, and thermal properties. Methods: Thermal flux measurements obtained with the Herschel-PACS instrument at 70, 100 and 160 μm, and whenever applicable, with Spitzer-MIPS at 24 and 70 μm, are modeled with radiometric techniques, in order to derive the objects' individual size, albedo and when possible beaming factor. Error bars are obtained from a Monte-Carlo approach. We look for correlations between these and other physical and orbital parameters. Results: Diameters obtained for our sample range from 100 to 2400 km, and the geometric albedos (in V band) vary from 3.8% to 84.5%. The unweighted mean V geometric albedo for the whole sample is 11.2% (excluding Eris); 6.9% for the SDOs, and 17.0% for the detached objects (excluding Eris). We obtain new bulk densities for three binary systems: Ceto/Phorcys, Typhon/Echidna and Eris/Dysnomia. Apart from correlations clearly due to observational bias, we find significant correlations between albedo and diameter (more reflective objects being bigger), and between albedo, diameter and perihelion distance (brighter and bigger objects having larger perihelia). We discuss possible explanations for these correlations. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. PACS: The Photodetector Array Camera and Spectrometer is one of Herschel's instruments.Appendices are available in electronic form at http://www.aanda.org

  4. Motor asymmetry in elite fencers.

    PubMed

    Akpinar, Selcuk; Sainburg, Robert L; Kirazci, Sadettin; Przybyla, Andrzej

    2015-01-01

    The authors previously reported that asymmetrical patterns of hand preference are updated and modified by present sensorimotor conditions. They examined whether participation in long-term training in the upper extremity sport fencing might modify arm selection and performance asymmetries. Eight fencers and eight nonfencers performed reaching movements under 3 experimental conditions: (a) nonchoice right, (b) nonchoice left, and (c) choice, either right or left arm as selected by subject. The nonchoice conditions allowed assessment of potential interlimb differences in movement performance, while the choice condition allowed assessment of the frequency and pattern of arm selection across subject groups. Our findings showed that the athlete group showed substantially greater symmetry in the performance and selection measures. These findings suggest that arm selection and performance asymmetries can be altered by intense long-term practice.

  5. [Temporal and Spatial Characteristics of Lake Taihu Surface Albedo and Its Impact Factors].

    PubMed

    Cao, Chang; Li, Xu-hui; Zhang, Mi; Liu, Shou-dong; Xiao, Wei; Xiao, Qi-tao; Xu, Jia-ping

    2015-10-01

    Lake surface albedo determines energy balance of water-atmospheric interface and water physical environment. Solar elevation angle, cloudiness, wind speed, water quality and other factors can affect lake surface albedo. Using solar radiation, wind speed, and water quality data (turbidity and chlorophyll-a concentration) which were observed in four eddy covariance sites (Meiliangwan, Dapukou, Bifenggang and Xiaoleishan i. e. MLW, DPK, BFG and XLS) in Lake Taihu and clearness index (k(t)), the influence of these factors on Lake Taihu surface albedo and the reasons that led to its spatial difference were investigated. The results showed that solar elevation angle played a leading role in the diurnal and seasonal change of lake surface albedo; lake surface albedo reached two peaks in 0 < k(t) < 0.1 and 0.4 < k(t) < 0.6 respectively, when solar elevation angle was below 35 degrees. The surface albedo increased with the increasing wind speed, turbidity and chlorophyll-a concentration. However, wind could indirectly affect surface albedo through leading to the changes in sediment resuspension and chlorophyll-a distribution. The sequence of albedo in the four sites was XLS > BFG > DPK > MLW. XLS and BFG belonged to the higher albedo group, while DPK and MLW belonged to the lower albedo group. The different biological environments caused by aquatic macrophytes and algae resulting in the spatial variation of Lake Taihu surface albedo. The relationship between albedo and chlorophyll-a concentration was not a very sensitive factor for indicating the outbreak of algae. This study can provide theoretical reference for lake albedo parameterization.

  6. A three-parameter asteroid taxonomy

    NASA Technical Reports Server (NTRS)

    Tedesco, Edward F.; Williams, James G.; Matson, Dennis L.; Veeder, Glenn J.; Gradie, Jonathan C.

    1989-01-01

    Broadband U, V, and x photometry together with IRAS asteroid albedos have been used to construct an asteroid classification system. The system is based on three parameters (U-V and v-x color indices and visual geometric albedo), and it is able to place 96 percent of the present sample of 357 asteroids into 11 taxonomic classes. It is noted that all but one of these classes are analogous to those previously found using other classification schemes. The algorithm is shown to account for the observational uncertainties in each of the classification parameters.

  7. Spent fuel measurements. passive neutron albedo reactivity (PNAR) and photon signatures

    SciTech Connect

    Eigenbrodt, Julia; Menlove, Howard Olsen

    2016-03-29

    The International Atomic Energy Agency’s (IAEA) safeguards technical objective is the timely detection of a diversion of a significant quantity of nuclear material from peaceful activities to the manufacture of nuclear weapons or of other nuclear explosive devices or for purposes unknown, and deterrence of such diversion by the risk of early detection. An important IAEA task towards meeting this objective is the ability to accurately and reliably measure spent nuclear fuel (SNF) to verify reactor operating parameters and verify that the fuel has not been removed from reactors or SNF storage facilities. This dissertation analyzes a method to improve the state-of-the-art of nuclear material safeguards measurements using two combined measurement techniques: passive neutron albedo reactivity (PNAR) and passive spectral photon measurements.

  8. A Robust Quantification of Galaxy Cluster Morphology Using Asymmetry and Central Concentration

    NASA Astrophysics Data System (ADS)

    Nurgaliev, D.; McDonald, M.; Benson, B. A.; Miller, E. D.; Stubbs, C. W.; Vikhlinin, A.

    2013-12-01

    We present a novel quantitative scheme of cluster classification based on the morphological properties that are manifested in X-ray images. We use a conventional radial surface brightness concentration parameter (c SB) as defined previously by others and a new asymmetry parameter, which we define in this paper. Our asymmetry parameter, which we refer to as photon asymmetry (A phot), was developed as a robust substructure statistic for cluster observations with only a few thousand counts. To demonstrate that photon asymmetry exhibits better stability than currently popular power ratios and centroid shifts, we artificially degrade the X-ray image quality by (1) adding extra background counts, (2) eliminating a fraction of the counts, (3) increasing the width of the smoothing kernel, and (4) simulating cluster observations at higher redshift. The asymmetry statistic presented here has a smaller statistical uncertainty than competing substructure parameters, allowing for low levels of substructure to be measured with confidence. A phot is less sensitive to the total number of counts than competing substructure statistics, making it an ideal candidate for quantifying substructure in samples of distant clusters covering a wide range of observational signal-to-noise ratios. Additionally, we show that the asymmetry-concentration classification separates relaxed, cool-core clusters from morphologically disturbed mergers, in agreement with by-eye classifications. Our algorithms, freely available as Python scripts (https://github.com/ndaniyar/aphot), are completely automatic and can be used to rapidly classify galaxy cluster morphology for large numbers of clusters without human intervention.

  9. MERIS albedo climatology for FRESCO+ O2 A-band cloud retrieval

    NASA Astrophysics Data System (ADS)

    Popp, C.; Wang, P.; Brunner, D.; Stammes, P.; Zhou, Y.; Grzegorski, M.

    2011-03-01

    retrieval which relies on accurate cloud information at small cloud fractions. In addition, overestimates along coastlines and underestimates in the Intertropical Convergence Zone introduced by the GOME LER were eliminated. While effective cloud fractions over the Saharan desert and the Arabian peninsula are successfully reduced in January, they are still too high in July relative to HICRU due to FRESCO+'s large sensitivity to albedo inaccuracies of highly reflecting targets and inappropriate aerosol information which hampers an accurate albedo retrieval. Finally, NO2 tropospheric vertical column densities and O3 total columns were derived with the FRESCO+ cloud parameters from the new dataset and it is found that the MERIS BSA climatology has a pronounced and beneficial effect on regional scale. Apart from FRESCO+, the new MERIS albedo dataset is applicable to any cloud retrieval algorithms using the O2 A-band or the O2-O2 absorption band around 477 nm. Moreover, the by-product of BSA at 442 nm can be used in NO2 remote sensing and the BSA at 620 nm, 665 nm, and 681 nm could be integrated in current H2O retrievals.

  10. MERIS albedo data set with improved spatial resolution for SCIAMACHY NO2 retrieval over the European Alpine region

    NASA Astrophysics Data System (ADS)

    Popp, Christoph; Brunner, Dominik; Zhou, Yipin; Wang, Ping; Stammes, Piet

    Despite NOx emissions have been reduced in the past two decades in Switzerland, the NO2 concentrations today still occasionally exceed their threshold as in most other European coun-tries. In addition, the neighboring Po Valley in Northern Italy is well known for generally high levels of air pollutants which are often transported to the southern part of Switzerland. Vertical tropospheric column (VTC) densities of NO2 obtained from spaceborne UV/VIS sensors pro-vide spatially homogeneous information complementing local ground-based measurements. For instance, SCIAMACHY (Scanning Imaging Absorption SpectroMeter for Atmospheric Cartog-raphY) derived NO2-VTC are available from 2002 onward potentially enabling trend analysis as well as monitoring of air quality in our region of interest. In general, a large part of the NO2-VTC retrieval uncertainty can be assigned to the air mass factor which, in turn, depends on model parameters such as surface albedo, surface pressure, cloud fraction and cloud pres-sure. Previous studies indicated that improving the spatial resolution of these forward param-eters can lead to more accurate estimates of NO2-VTC. Herein, we concentrate on the surface albedo. In ESA's TEMIS (Tropospheric Emission Monitoring Internet Service) project, the SCIAMACHY NO2-VTC retrieval makes use of combined GOME/TOMS Lambertian equiva-lent reflectance data mapped onto a grid with a spatial resolution of 1x1. However, variations of surface albedo at the scale of individual satellite pixels (30x60km2 for SCIAMACHY) are difficult to be resolved with this grid size, especially in areas like the European Alps and ad-jacent regions characterized by heterogeneous land cover. For these reasons, we compiled a new land surface albedo climatology for each month of the year from MERIS (The Medium Resolution Imaging Spectrometer) Albedomap data covering the period October 2002 to Oc-tober 2006 with a spatial resolution of 0.25x0.25. The wavelength bands considered are

  11. $\\bar d - \\bar u$ asymmetry in the proton in chiral effective theory

    SciTech Connect

    Salamu, Yusupujiang; Ji, Chueng -Ryong; Melnitchouk, W.; Wang, P.

    2015-03-25

    We compute the $\\bar d - \\bar u$ asymmetry in the proton in chiral effective theory, including both nucleon and Δ degrees of freedom, within both relativistic and heavy baryon frameworks. In addition to the distribution at $x>0$, we estimate the correction to the integrated asymmetry arising from zero momentum contributions from pion rainbow and bubble diagrams at $x=0$, which have not been accounted for in previous analyses. In conclusion, we find that the empirical $x$ dependence of $\\bar d - \\bar u$ as well as the integrated asymmetry can be well reproduced in terms of a transverse momentum cutoff parameter.

  12. UV signatures of carbonaceous species on low-albedo asteroids

    NASA Astrophysics Data System (ADS)

    Hendrix, A.; Vilas, F.

    2014-07-01

    Asteroids in the low-albedo classes (C, B, G, F) are known to have spectra that are relatively feature-free in the visible/near-infrared (VNIR) spectral region, making them classically difficult to study in terms of surface mineralogy. Many of these bodies exhibit a 3-micron absorption band (e.g., [1]), which can be used to study hydration and organics. The primary other spectrally active region --- less well studied so far --- is the ultraviolet (UV). In this study, we utilize UV spectra of low-albedo asteroids (C, B, G, and F class) to study surface composition. In particular, we investigate implications for the presence of carbonaceous compounds, including tholins and Polycyclic Aromatic Hydrocarbons (PAHs), which have unique spectral features in the UV. Low-albedo asteroids are typically rather bland spectrally at VNIR wavelengths. Many of these objects exhibit an absorption band near 3 microns, indicative of some type of hydration (OH and-or H_2O). A subset of the asteroids with the 3-micron features also exhibit absorption near 0.7 microns, due to a ferrous-ferric charge-transfer transition likely resulting from aqueous alteration (the interaction of material with liquid water formed by melting of water upon a heating event). Some asteroids likely do not exhibit these features due to a history of heating experienced at some point in the asteroid's evolution. Despite having little spectral activity in the VNIR, all low-albedo asteroids absorb at wavelengths shorter than ˜500 nm. This has been generally attributed to a ferric-iron intervalence charge-transfer transition absorption. Carbon-bearing phases have long been assumed to be important on low-albedo asteroids (e.g., [2]) due to the dark, mostly-featureless VNIR spectra of these bodies. However, there are many forms of carbonaceous species and the species are expected to undergo phase modifications (e.g., due to thermal, aqueous, and radiation processes) that affect the spectra [3,7]. Tholins are residues

  13. Critical asymmetry in renormalization group theory for fluids.

    PubMed

    Zhao, Wei; Wu, Liang; Wang, Long; Li, Liyan; Cai, Jun

    2013-06-21

    The renormalization-group (RG) approaches for fluids are employed to investigate critical asymmetry of vapour-liquid equilibrium (VLE) of fluids. Three different approaches based on RG theory for fluids are reviewed and compared. RG approaches are applied to various fluid systems: hard-core square-well fluids of variable ranges, hard-core Yukawa fluids, and square-well dimer fluids and modelling VLE of n-alkane molecules. Phase diagrams of simple model fluids and alkanes described by RG approaches are analyzed to assess the capability of describing the VLE critical asymmetry which is suggested in complete scaling theory. Results of thermodynamic properties obtained by RG theory for fluids agree with the simulation and experimental data. Coexistence diameters, which are smaller than the critical densities, are found in the RG descriptions of critical asymmetries of several fluids. Our calculation and analysis show that the approach coupling local free energy with White's RG iteration which aims to incorporate density fluctuations into free energy is not adequate for VLE critical asymmetry due to the inadequate order parameter and the local free energy functional used in the partition function.

  14. Fluctuating asymmetry and testing isolation of Montana grizzly bear populations

    USGS Publications Warehouse

    Picton, Harold D.; Palmisciano, Daniel A.; Nelson, Gerald

    1990-01-01

    Fluctuating asymmetry of adult skulls was used to test he genetic isolation of the Yellowstone grizzly bear population from its nearest neighbor. An overall summary statistic was used in addition to 16 other parameters. Tests found the males of the Yellowstone populaion to be more vaiable than those of the North Conitinental Divide Exosystem. Evidence for precipitaiton effects is also included. This test tends to support the existing management haypothesis that the Yellowstone population is isolatied.

  15. Independent pixel and Monte Carlo estimates of stratocumulus albedo

    NASA Technical Reports Server (NTRS)

    Cahalan, Robert F.; Ridgway, William; Wiscombe, Warren J.; Gollmer, Steven; HARSHVARDHAN

    1994-01-01

    Monte Carlo radiative transfer methods are employed here to estimate the plane-parallel albedo bias for marine stratocumulus clouds. This is the bias in estimates of the mesoscale-average albedo, which arises from the assumption that cloud liquid water is uniformly distributed. The authors compare such estimates with those based on a more realistic distribution generated from a fractal model of marine stratocumulus clouds belonging to the class of 'bounded cascade' models. In this model the cloud top and base are fixed, so that all variations in cloud shape are ignored. The model generates random variations in liquid water along a single horizontal direction, forming fractal cloud streets while conserving the total liquid water in the cloud field. The model reproduces the mean, variance, and skewness of the vertically integrated cloud liquid water, as well as its observed wavenumber spectrum, which is approximately a power law. The Monte Carlo method keeps track of the three-dimensional paths solar photons take through the cloud field, using a vectorized implementation of a direct technique. The simplifications in the cloud field studied here allow the computations to be accelerated. The Monte Carlo results are compared to those of the independent pixel approximation, which neglects net horizontal photon transport. Differences between the Monte Carlo and independent pixel estimates of the mesoscale-average albedo are on the order of 1% for conservative scattering, while the plane-parallel bias itself is an order of magnitude larger. As cloud absorption increases, the independent pixel approximation agrees even more closely with the Monte Carlo estimates. This result holds for a wide range of sun angles and aspect ratios. Thus, horizontal photon transport can be safely neglected in estimates of the area-average flux for such cloud models. This result relies on the rapid falloff of the wavenumber spectrum of stratocumulus, which ensures that the smaller

  16. Revised albedos of Trojan asteroids (911) Agamemnon and (4709) Ennomos

    NASA Astrophysics Data System (ADS)

    Shevchenko, V. G.; Slyusarev, I. G.; Belskaya, I. N.

    2014-01-01

    CCD-photometry was performed for two Jupiter Trojan asteroids (911) Agamemnon and (4709) Ennomos for which the diameters were obtained from occultation events. New data on rotation periods, lightcurve amplitudes, color indices, magnitude-phase slopes, and absolute magnitudes were obtained for these asteroids. We have used the diameters from occultations (166 and 99 km) and new data on absolute magnitudes at the instant occultation (7.95 and 8.85 mag) to revise their albedos to 0.042 (911 Agamemnon) and 0.052 (4709 Ennomos).

  17. Oceanic phytoplankton, atmospheric sulphur, cloud albedo and climate

    NASA Astrophysics Data System (ADS)

    Charlson, Robert J.; Warren, Stephen G.; Lovelock, James E.; Andreae, Meinrat O.

    1987-04-01

    The major source of cloud-condensation nuclei (CCN) over the oceans appears to be dimethylsulphide, which is produced by planktonic algae in sea water and oxidizes in the atmosphere to form a sulphate aerosol. Because the reflectance (albedo) of clouds (and thus the earth's radiation budget) is sensitive to CCN density, biological regulation of the climate is possible through the effects of temperature and sunlight on phytoplankton population and dimethylsulphide production. To counteract the warming due to doubling of atmospheric CO2, an approximate doubling of CCN would be needed.

  18. Effect of reflectance model choice on earthshine-based terrestrial albedo determinations.

    NASA Astrophysics Data System (ADS)

    Thejll, Peter; Gleisner, Hans; Flynn, Chris

    2016-04-01

    Earthshine observations can be used to determine near-hemispheric average terrestrial albedos by careful observation of the relative strength of the earthshine-lit half of the Moon coupled with correct modelling of the reflectances of Earth and Moon, as well as lunar single-scattering albedo maps. Using our own observations of the earthshine, from Mauna Loa Observatory in 2011-12, we investigate the influence of the choice of bidirectional reflectance models for the Moon on derived terrestrial albedos. We find a considerable dependence on albedo results in this choice, and discuss ways to determine what the origin of the dependence is - e.g is it in the joint choices of lunar and terrestrial BRDFs, or is the choice of terrestrial BRDF less important than the lunar one? We report on the results of modelling lunar reflectance and albedo in 6 ways and terrestrial reflectance in two ways, assuming a uniform single-scattering albedo on Earth.

  19. Size and albedo distributions of asteroids in cometary orbits using WISE data

    NASA Astrophysics Data System (ADS)

    Licandro, J.; Alí-Lagoa, V.; Tancredi, G.; Fernández, Y.

    2016-01-01

    Context. Determining whether asteroids in cometary orbits (ACOs) are dormant or extinct comets is relevant for understanding the end-states of comets and the sizes of the comet population. Aims: We intend to study the value distributions of effective diameter (D), beaming parameter (η), and visible geometric albedo (pV) of ACO populations, which can be derived from NASA's Wide-field Infrared Explorer (WISE) observations, and we aim to compare these with the same, independently determined properties of the comets. Methods: The near-Earth asteroid thermal model (NEATM) is used with WISE data and the absolute magnitude (H) of the ACOs to compute the D, pV and η. Results: We obtained D and pV for 49 ACOs in Jupiter family cometary orbits (JF-ACOs) and 16 ACOs in Halley-type cometary orbits (Damocloids). We also obtained the infrared beaming parameter η for 45 of them. All but three JF-ACOs (95% of the sample) present a low albedo compatible with a cometary origin. The pV and η distributions of both ACO populations are very similar. For the entire sample of ACOs, the mean geometric albedo is p̅V = 0.05±0.02, (p̅V = 0.05±0.01 and p̅V = 0.05±0.02 for JF-ACOs and for Damocloids, respectively) compatible with a narrow albedo distribution similar to that of the Jupiter family comets (JFCs), with a p̅V ~ 0.04. The mean beaming parameter is η̅ = 1.0±0.2. We find no correlations between D, pV, or η. We also compare the cumulative size distribution (CSD) of ACOs, Centaurs, and JFCs. Although the Centaur sample contains larger objects, the linear parts in their log-log plot of the CSDs presents a similar cumulative exponent (β = 1.85 ± 0.30 and 1.76 ± 0.35, respectively). The CSD for Damocloids presents a much shallower exponent β = 0.89 ± 0.17. Conclusions: The pV- and η-value distributions of ACOs are very similar to those of JF comet (JFCs) nuclei. The ACOs in Tancredi's list are the best possible candidates to be dormant/inactive comets. The CSD for JF

  20. Time-Dependent CP Asymmetries in b {yields} s Penguins

    SciTech Connect

    Miyake, H.

    2006-07-11

    We present measurements of time-dependent CP asymmetry parameters in B{sup 0} {yields} {phi}(1020)K{sup 0}, {eta}'K{sup 0}, K{sub S}{sup 0}K{sub S}{sup 0}K{sub S}{sup 0} K{sub S}{sup 0}, K{sub S}{sup 0}{pi}{sup 0}, f{sub 0}(980)K{sub S}{sup 0}, {omega}(782)K{sub S}{sup 0} and K{sup +}K{sup -}K{sub S}{sup 0} decays based on a sample of 386 x 106BB(bar sign) pairs collected at the {upsilon}(4S) resonance with the Belle detector at the KEKB energy asymmetric e+e- collider. These decays are dominated by the b {yields} s gluonic penguin transition and are sensitive to new CP-violating phases from physics beyond the standard model. One neutral meson is fully reconstructed in one of the specified decay channels, and the flavor of the accompanying B meson is identified from its decay products. CP-violation parameters are obtained from the asymmetries in the distributions of the proper-time intervals between the two B decays. We also perform measurement of time-dependent CP asymmetry parameters in B{sup 0} {yields} K{sub S}{sup 0}{gamma} decay that is dominated by the b {yields} s radiative penguin.

  1. The effects of atmospheric dust on observations of Martian surface albedo

    NASA Technical Reports Server (NTRS)

    Lee, S. W.; Clancy, R. T.

    1991-01-01

    The Mariner 9 and Viking missions provided abundant evidence that aeolian processes are active over much of surface of Mars. A radiative transfer model was developed which allows the effects of atmospheric dust loading and variable surface albedo to be investigated. This model incorporated atmospheric dust opacity, the single scattering albedo, and particle phase function of atmospheric dust, the bidirectional; reflectance of the surface, and variable lighting and viewing geometry. The Cerberus albedo feature was examined in detail using this technique.

  2. Detecting Low-Contrast Features in the Cosmic Ray Albedo Proton Map of the Moon

    NASA Technical Reports Server (NTRS)

    Wilson, J. K.; Schwadron, N.; Spence, H. E.; Golightly, M. J.; Case, A. W.; Smith, S.; Blake, J. B.; Kasper, J.; Looper, M. D.; Mazur, J. E.; Townsend, L. W.; Zeitlin, C.; Stubbs, T. J.

    2014-01-01

    High energy cosmic rays constantly bombard the lunar regolith, producing (via nuclear evaporation) secondary 'albedo' or 'splash' particles like protons and neutrons, some of which escape back to space. Lunar Prospector and the Lunar Reconnaissance Orbiter (LRO), have shown that the energy distribution of albedo neutrons is modulated by the elemental composition of the lunar regolith, and by ice deposits in permanently shadowed polar craters. Here we investigate an analogous phenomenon with high energy ((is) approximately 100 MeV) lunar albedo protons.

  3. DOSIMETRIC PROPERTIES OF THE NEW TLD ALBEDO NEUTRON DOSEMETER AWST-TL-GD 04.

    PubMed

    Haninger, T; Henniger, J

    2016-09-01

    A new official albedo dosemeter based on thermoluminescent detectors has been introduced in 2015 by the individual monitoring service of the Helmholtz Zentrum München for monitoring persons who are exposed occupationally against photon and neutron radiation. To enhance the sensitivity for fast neutrons, a new badge with an enlarged albedo window has been developed at TU Dresden. The properties of the new albedo dosemeter are discussed, and the results of official intercomparisons and field calibrations are shown.

  4. Sunlight, Sea Ice, and the Ice Albedo Feedback in a Changing Arctic Sea Ice Cover

    DTIC Science & Technology

    2013-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Sunlight, Sea Ice, and the Ice Albedo Feedback in a...ice age, and iv) onset dates of melt and freezeup. 4. Assess the magnitude of the contribution from ice- albedo feedback to the observed decrease of...COVERED 00-00-2013 to 00-00-2013 4. TITLE AND SUBTITLE Sunlight, Sea Ice, and the Ice Albedo Feedback in a Changing Arctic Sea Ice Cover 5a

  5. Condylar-mandibular asymmetry, a reality.

    PubMed

    Boratto, R; Gambardella, U; Micheletti, P; Pagliani, L; Preda, L; Hansson, T L

    2002-01-01

    The aim of this study is to evaluate the possibility to recognize a condylar-mandibular asymmetry through a panoramic radiograph. Results from a previous work, in which 100 skulls from the Museum of the Institute of Anatomy of the University of Pavia were studied and measured, showed the presence of asymmetry. Using the same skulls we examined the possible correlation between morphological and radiological data. We did not find out correlation's between the condylar asymmetry evaluated at the anatomical level and the radiological asymmetry which was indeed found. This is probably due to the different positioning of the jaws during the two different measuring processes. Nevertheless our results confirm the daily experience of dentistry: asymmetry of mandibular condyle can be one of the mayor causes for the asymmetry of the stomatognatic apparatus.

  6. Changes on albedo after a large forest fire in Mediterranean ecosystems

    NASA Astrophysics Data System (ADS)

    Quintano, Carmen; Fernández-Manso, Alfonso; Fernández-García, Victor; Marcos, Elena; Calvo, Leonor

    2015-09-01

    Fires are one of the main causes of environmental alteration in Mediterranean forest ecosystems. Albedo varies and evolves seasonally based on solar illumination. It is greatly influenced by changes on vegetation: vegetation growth, cutting/planting forests or forest fires. This work analyzes albedo variations due to a large forest fire that occurred on 19- 21 September 2012 in northwestern Spain. From this area, albedo post-fire images (immediately and 1-year after fire) were generated from Landsat 7 Enhanced Thematic Mapper (ETM+) data. Specifically we considered total shortwave albedo, total-, direct-, and diffuse-visible, and near-infrared albedo. Nine to twelve weeks after fire, 111 field plots were measured (27 unburned plots, 84 burned plots). The relationship between albedo values and thematic class (burned/unburned) was evaluated by one-way analysis of variance. Our results demonstrate that albedo changes were related to burned/unburned variable with statistical significance, indicating the importance of forestry areas as regulators of land surface energy fluxes and revealing the potential of post-fire albedo for assessing burned areas. Future research, however, is needed to evaluate the persistence of albedo changes.

  7. The accuracy of satellite-derived albedo for northern alpine and glaciated land covers

    NASA Astrophysics Data System (ADS)

    Williamson, Scott N.; Copland, Luke; Hik, David S.

    2016-09-01

    Alpine and Arctic land cover can present a challenge for the validation of satellite-derived albedo measurements due, in part, to the complex terrain and logistical difficulty of accessing these regions. We compared measurements of albedo on transects from northern mountain land covers (snowfield, glacier ice, tundra, saline silt river delta) and over a large elevation range to the coincident 8-day MODIS (MCD43) albedo product. We also compared field measurements at snow covered sites to the coincident daily MODIS (MOD10A1) snow albedo product. For each transect, we measured a range of albedo values, with the least variability on the silt river delta (range = 0.084) and the largest over mid-elevation glacier ice (range = 0.307). The highest elevation snowfield (0.170) had nearly the same range of albedo values as tundra (0.164). The MODIS shortwave White Sky Albedo product (MCD43A3) was highly correlated with the field transect albedo (R2 = 0.96), with a Root Mean Square Error (RMSE) of 0.061. The MODIS shortwave Black Sky Albedo product was similarly correlated with field transects (R2 = 0.96; RMSE = 0.063). These results indicate that remote observation of albedo over snow covered and alpine terrain is well constrained and consistent with other studies. Albedo varied by ∼15% both spatially and temporally for the high elevation snowfields at the point in the season where albedo variation should be at its minimum. There were several instances where MCD43A3 albedo was not produced over snow and was instead classified as cloud covered, despite field observations of cloud free skies. There were also several instances where daily MOD10A1 albedo was produced during the coincident 8-day period at these locations. This suggests that the cloud mask in the MCD43 product is overly conservative over snow. Spatial variation in albedo within the MODIS grid cell (500 m), especially for snow and glacier ice, combined with the uncertainty associated with positional accuracy of

  8. A comparative study of the effects of albedo change on drought in semi-arid regions

    NASA Technical Reports Server (NTRS)

    Charney, J.; Quirk, W. J.; Chow, S.-H.; Kornfield, J.

    1977-01-01

    Numerical simulation studies of the effects of changes in albedo on rainfall involve comparisons of semiarid areas, lying at the boundary between a major desert and an adjacent monsoonal region, with areas of the same size located within the monsoonal region itself. The sensitivity of the rainfall to the ground hydrology was determined by performing the albedo simulations with two different evapotranspiration parameterizations, one giving too high evaporation over land and the other giving negligible evaporation over land. The evaporation rate is, in general, found to have as important an effect as changes in albedo. The mechanism by which an increase of albedo reduces the rainfall during conditions of high evaporation is considered.

  9. Natural versus anthropogenic factors affecting low-level cloud albedo over the North Atlantic

    NASA Technical Reports Server (NTRS)

    Falkowski, Paul G.; Kim, Yongseung; Kolber, Zbigniew; Wilson, Cara; Wirick, Creighton; Cess, Robert

    1992-01-01

    Cloud albedo plays a key role in regulating earth's climate. Cloud albedo depends on column-integrated liquid water content and the density of cloud condensation nuclei, which consists primarily of submicrometer-sized aerosol sulfate particles. A comparison of two independent satellite data sets suggests that, although anthropogenic sulfate emissions may enhance cloud albedo immediately adjacent to the east coast of the United States, over the central North Atlantic Ocean the variability in albedo can be largely accounted for by natural marine and atmospheric processes that probably have remained relatively constant since the beginning of the industrial revolution.

  10. Diurnal variability of the planetary albedo - An appraisal with satellite measurements and general circulation models

    NASA Technical Reports Server (NTRS)

    Potter, G. L.; Cess, R. D.; Minnis, P.; Harrison, E. F.; Ramanathan, V.

    1988-01-01

    An atmospheric radiation model is used here to illustrate several features associated with modeling the diurnal cycle of the planetary albedo. It is found that even for clear regions there appear to be deficiencies in our knowledge of how to model this quantity. The diurnal amplitude factor, defined as the ratio of the diurnally averaged planetary albedo to that at noon, between two GCMs and measurements made from a geostationary satellite. While reasonable consistency is found, the comparisons underscore difficulties associated with converting local-time albedo measurements, as made from sun-synchronous satellites, to diurnally averaged albedos.

  11. New technique to improve the accuracy of albedo neutron dosimeter evaluations

    NASA Astrophysics Data System (ADS)

    Hankins, D. E.

    The calibration factor for albedo neutron dosimeters varies greatly depending upon the energy of the neutrons in the exposure. Calibration results obtained over an eight-year period at each Lawrence Livermore National Laboratory facility where neutron exposure may occur were reviewed. A stronger relationship than expected was found between the ratio of the readings of the 9-in. to 3-in. spheres and the percent thermal. Readings from personnel and albedo badges were reviewed. The readings were consistent with the use of a calibration factor for the albedo dosimeter which varies with changes in the ratio of the personnel and albedo dosimeter TLD readings.

  12. Vegetation controls on northern high latitude snow-albedo feedback: observations and CMIP5 model simulations.

    PubMed

    Loranty, Michael M; Berner, Logan T; Goetz, Scott J; Jin, Yufang; Randerson, James T

    2014-02-01

    The snow-masking effect of vegetation exerts strong control on albedo in northern high latitude ecosystems. Large-scale changes in the distribution and stature of vegetation in this region will thus have important feedbacks to climate. The snow-albedo feedback is controlled largely by the contrast between snow-covered and snow-free albedo (Δα), which influences predictions of future warming in coupled climate models, despite being poorly constrained at seasonal and century time scales. Here, we compare satellite observations and coupled climate model representations of albedo and tree cover for the boreal and Arctic region. Our analyses reveal consistent declines in albedo with increasing tree cover, occurring south of latitudinal tree line, that are poorly represented in coupled climate models. Observed relationships between albedo and tree cover differ substantially between snow-covered and snow-free periods, and among plant functional type. Tree cover in models varies widely but surprisingly does not correlate well with model albedo. Furthermore, our results demonstrate a relationship between tree cover and snow-albedo feedback that may be used to accurately constrain high latitude albedo feedbacks in coupled climate models under current and future vegetation distributions.

  13. On the importance of interpolation schemes for albedo data from local to global grid

    NASA Astrophysics Data System (ADS)

    Preuschmann, Swantje; Jacob, Daniela; Löw, Alexander

    2013-04-01

    Surface albedo has a key role in Earth's radiation balance. As vegetation cover is influencing the albedo of solid surfaces, it is clear that land cover changes are leading to changes in the radiation balance and further are influencing the whole Earth's energy budget. It is obvious, that a forested area reflects sunlight differently compared to a sparsely vegetated area of shrubs. Different studies have shown, that certain land cover types (even compounds) have a characteristic annual cycle of the albedo (Moody et al. 2005 and Preuschmann, 2012). An annual cycle for one land cover type might vary in a year about 2%. The difference of the surface albedo of a forested area in summer to an agricultural area at the same time is only about 0.5%. A major question in climate modelling under future conditions is to analyse the impact of land cover changes onto climate. Nevertheless for different reasons it is not easy to describe surface albedo changes due to land cover changes within a climate model. One reason is that differences in the albedo of different surfaces are comparatively small. Another reason is based in the spatial resolution of a climate model. Climate models are operating on grids with horizontal resolutions of 10x10 km² for regional models up to about 200x200 km² for global models with a spectral resolution of T63. This means, that spatial (and also temporal) mean values of surface albedo are taken into account. Therefore one grid box of a climate model is representing a composition of different surface albedos. For model validation, it is of interest to compare the modelled albedo data with observed albedo data, but a comparison is not as trivial as it looks in the first sight. One problematic is the necessity of comparing different data types in the same horizontal and temporal resolution. Commonly used satellite based albedo data are available in 0.05° horizontal resolution, which is about 5 km at the equator, for several-day means and monthly

  14. Albedo parametrization and reversibility of sea ice decay

    NASA Astrophysics Data System (ADS)

    Müller-Stoffels, M.; Wackerbauer, R.

    2012-02-01

    The Arctic's sea ice cover has been receding rapidly in recent years, and global climate models typically predict a further decline over the next century. It is an open question whether a possible loss of Arctic sea ice is reversible. We study the stability of Arctic model sea ice in a conceptual, two-dimensional energy-based regular network model of the ice-ocean layer that considers ARM's longwave radiative budget data and SHEBA albedo measurements. Seasonal ice cover, perennial ice and perennial open water are asymptotic states accessible by the model. We show that the shape of albedo parameterization near the melting temperature differentiates between reversible continuous sea ice decrease under atmospheric forcing and hysteresis behavior. Fixed points induced solely by the surface energy budget are essential for understanding the interaction of surface energy with the radiative forcing and the underlying body of ice/water, particularly close to a bifurcation point. Future studies will explore ice edge stability and reversibility in this lattice model, generalized to a latitudinal transect with spatiotemporal lateral atmospheric heat transfer and high spatial resolution.

  15. Soot climate forcing via snow and ice albedos

    PubMed Central

    Hansen, James; Nazarenko, Larissa

    2004-01-01

    Plausible estimates for the effect of soot on snow and ice albedos (1.5% in the Arctic and 3% in Northern Hemisphere land areas) yield a climate forcing of +0.3 W/m2 in the Northern Hemisphere. The “efficacy” of this forcing is ∼2, i.e., for a given forcing it is twice as effective as CO2 in altering global surface air temperature. This indirect soot forcing may have contributed to global warming of the past century, including the trend toward early springs in the Northern Hemisphere, thinning Arctic sea ice, and melting land ice and permafrost. If, as we suggest, melting ice and sea level rise define the level of dangerous anthropogenic interference with the climate system, then reducing soot emissions, thus restoring snow albedos to pristine high values, would have the double benefit of reducing global warming and raising the global temperature level at which dangerous anthropogenic interference occurs. However, soot contributions to climate change do not alter the conclusion that anthropogenic greenhouse gases have been the main cause of recent global warming and will be the predominant climate forcing in the future. PMID:14699053

  16. Tackling regional climate change by leaf albedo bio-geoengineering.

    PubMed

    Ridgwell, Andy; Singarayer, Joy S; Hetherington, Alistair M; Valdes, Paul J

    2009-01-27

    The likelihood that continuing greenhouse-gas emissions will lead to an unmanageable degree of climate change has stimulated the search for planetary-scale technological solutions for reducing global warming ("geoengineering"), typically characterized by the necessity for costly new infrastructures and industries. We suggest that the existing global infrastructure associated with arable agriculture can help, given that crop plants exert an important influence over the climatic energy budget because of differences in their albedo (solar reflectivity) compared to soils and to natural vegetation. Specifically, we propose a "bio-geoengineering" approach to mitigate surface warming, in which crop varieties having specific leaf glossiness and/or canopy morphological traits are specifically chosen to maximize solar reflectivity. We quantify this by modifying the canopy albedo of vegetation in prescribed cropland areas in a global-climate model, and thereby estimate the near-term potential for bio-geoengineering to be a summertime cooling of more than 1 degrees C throughout much of central North America and midlatitude Eurasia, equivalent to seasonally offsetting approximately one-fifth of regional warming due to doubling of atmospheric CO(2). Ultimately, genetic modification of plant leaf waxes or canopy structure could achieve greater temperature reductions, although better characterization of existing intraspecies variability is needed first.

  17. Lunar Proton Albedo Anomalies: Soil, Surveyors, and Statistics

    NASA Astrophysics Data System (ADS)

    Wilson, J. K.; Schwadron, N.; Spence, H. E.; Case, A. W.; Golightly, M. J.; Jordan, A.; Looper, M. D.; Petro, N. E.; Robinson, M. S.; Stubbs, T. J.; Zeitlin, C. J.; Blake, J. B.; Kasper, J. C.; Mazur, J. E.; Smith, S. S.; Townsend, L. W.

    2014-12-01

    Since the launch of LRO in 2009, the CRaTER instrument has been mapping albedo protons (~100 MeV) from the Moon. These protons are produced by nuclear spallation, a consequence of galactic cosmic ray (GCR) bombardment of the lunar regolith. Just as spalled neutrons and gamma rays reveal elemental abundances in the lunar regolith, albedo protons may be a complimentary method for mapping compositional variations. We presently find that the lunar maria have an average proton yield 0.9% ±0.3% higher than the average yield in the highlands; this is consistent with neutron data that is sensitive to the regolith's average atomic weight. We also see cases where two or more adjacent pixels (15° × 15°) have significantly anomalous yields above or below the mean. These include two high-yielding regions in the maria, and three low-yielding regions in the far-side highlands. Some of the regions could be artifacts of Poisson noise, but for completeness we consider possible effects from compositional anomalies in the lunar regolith, including pyroclastic flows, antipodes of fresh craters, and so-called "red spots". We also consider man-made landers and crash sites that may have brought elements not normally found in the lunar regolith.

  18. Mars - Experimental study of albedo changes caused by dust fallout

    NASA Technical Reports Server (NTRS)

    Wells, E. N.; Veverka, J.; Thomas, P.

    1984-01-01

    A laboratory apparatus was used to simulate the uniform fallout and deposition of particles 1 to 5 microns in diameter in an experimental study on how the spectral and photometric properties of representative Martian areas are affected by fallout of atmospheric dust (smaller than or equalling 60 microns) suspended during dust storms. In this study, measurements are made in the changes in reflectance at optical and near-infrared wavelengths (0.4 to 1.2 micron) caused by deposition of varying amounts of a Mars-analog dust on bright and dark substrates before and after deposition of 6 x 10 to the -5th to 1.5 x 10 to the -3rd g/sq cm of simulated fallout. It is believed that only small amounts of dust particles (approximately 3 x 10 to the -4th g/sq cm) are needed to make significant albedo changes in dark areas of Mars, and that this would rule out uniform dust deposition on the surface of the planet. Data also indicate that other high albedo features like bright crater-related wind streaks may not be areas of significant sediment deposits. Laboratory simulations have permitted estimates of how much the reflectance of an area on Mars would change given a certain amount of dust fallout (g/sq cm) or reflectance data. These simulations may also be useful in tracking the transport and deposition of the dust.

  19. A cavity radiometer for Earth albedo measurement, phase 1

    NASA Technical Reports Server (NTRS)

    1987-01-01

    Radiometric measurements of the directional albedo of the Earth requires a detector with a flat response from 0.2 to 50 microns, a response time of about 2 seconds, a sensitivity of the order of 0.02 mw/sq cm, and a measurement uncertainty of less than 5 percent. Absolute cavity radiometers easily meet the spectral response and accuracy requirements for Earth albedo measurements, but the radiometers available today lack the necessary sensitivity and response time. The specific innovations addressed were the development of a very low thermal mass cavity and printed/deposited thermocouple sensing elements which were incorporated into the radiometer design to produce a sensitive, fast response, absolute radiometer. The cavity is applicable to the measurement of the reflected and radiated fluxes from the Earth surface and lower atmosphere from low Earth orbit satellites. The effort consisted of requirements and thermal analysis; design, construction, and test of prototype elements of the black cavity and sensor elements to show proof-of-concept. The results obtained indicate that a black body cavity sensor that has inherently a flat response from 0.2 to 50 microns can be produced which has a sensitivity of at least 0.02 mw/sq cm per micro volt ouput and with a time constant of less than two seconds. Additional work is required to develop the required thermopile.

  20. Ground Albedo Neutron Sensing (GANS) method for measurements of soil moisture in cropped fields

    NASA Astrophysics Data System (ADS)

    Andres Rivera Villarreyes, Carlos; Baroni, Gabriele; Oswald, Sascha E.

    2013-04-01

    Measurement of soil moisture at the plot or hill-slope scale is an important link between local vadose zone hydrology and catchment hydrology. However, so far only few methods are on the way to close this gap between point measurements and remote sensing. This study evaluates the applicability of the Ground Albedo Neutron Sensing (GANS) for integral quantification of seasonal soil moisture in the root zone at the scale of a field or small watershed, making use of the crucial role of hydrogen as neutron moderator relative to other landscape materials. GANS measurements were performed at two locations in Germany under different vegetative situations and seasonal conditions. Ground albedo neutrons were measured at (i) a lowland Bornim farmland (Brandenburg) cropped with sunflower in 2011 and winter rye in 2012, and (ii) a mountainous farmland catchment (Schaefertal, Harz Mountains) since middle 2011. At both sites depth profiles of soil moisture were measured at several locations in parallel by frequency domain reflectometry (FDR) for comparison and calibration. Initially, calibration parameters derived from a previous study with corn cover were tested under sunflower and winter rye periods at the same farmland. GANS soil moisture based on these parameters showed a large discrepancy compared to classical soil moisture measurements. Therefore, two new calibration approaches and four different ways of integration the soil moisture profile to an integral value for GANS were evaluated in this study. This included different sets of calibration parameters based on different growing periods of sunflower. New calibration parameters showed a good agreement with FDR network during sunflower period (RMSE = 0.023 m3 m-3), but they underestimated soil moisture in the winter rye period. The GANS approach resulted to be highly affected by temporal changes of biomass and crop types which suggest the need of neutron corrections for long-term observations with crop rotation. Finally

  1. Discharge Asymmetry in Delta Bifurcations

    NASA Astrophysics Data System (ADS)

    Salter, G.; Paola, C.; Voller, V. R.

    2015-12-01

    Distributary networks are formed by channels which bifurcate downstream in a river delta. Sediment and water fluxes are often split unequally in delta bifurcations. Understanding flux asymmetry in distributary networks is important for predicting how a delta will respond to sea-level rise. We present results of a quasi-1D model of a delta bifurcation. Consistent with previous results, in the absence of deposition, stable bifurcations may be either symmetric or asymmetric, depending on flow conditions. However, in a depositional setting, a stable asymmetric flow partitioning is no longer possible, as the dominant branch becomes less and less steep relative to the other branch. This feedback eventually causes the second branch to become favored. For the depositional case, we identify three regimes of bifurcation behavior: 1) stable symmetric bifurcation, 2) "soft" avulsions where the dominant branch switches without complete abandonment of the previous channel, and 3) complete avulsions where one branch is completely abandoned. In each case, the bifurcation is symmetric in the long-term average, but the latter two allow for short-term asymmetry. We find that keeping upstream sediment and water discharges fixed, as downstream channel length increases the regime shifts from symmetric to soft avulsions to complete avulsions. In the two avulsion regimes we examine the effect of upstream sediment and water discharges and downstream channel length on avulsion period and maximum discharge ratio. Finally, we compare numerical modeling results to a fixed-wall bifurcation experiment. As in the numerical model, the presence or absence of a downstream sink exerts a strong control on system behavior. If a sink is present, a bifurcation may be asymmetric indefinitely. Conversely, without a sink the system is depositional, and the feedback between sediment discharge asymmetry and slope causes the bifurcation to remain symmetric in the long-term average.

  2. Quantum speed limits, coherence, and asymmetry

    NASA Astrophysics Data System (ADS)

    Marvian, Iman; Spekkens, Robert W.; Zanardi, Paolo

    2016-05-01

    The resource theory of asymmetry is a framework for classifying and quantifying the symmetry-breaking properties of both states and operations relative to a given symmetry. In the special case where the symmetry is the set of translations generated by a fixed observable, asymmetry can be interpreted as coherence relative to the observable eigenbasis, and the resource theory of asymmetry provides a framework to study this notion of coherence. We here show that this notion of coherence naturally arises in the context of quantum speed limits. Indeed, the very concept of speed of evolution, i.e., the inverse of the minimum time it takes the system to evolve to another (partially) distinguishable state, is a measure of asymmetry relative to the time translations generated by the system Hamiltonian. Furthermore, the celebrated Mandelstam-Tamm and Margolus-Levitin speed limits can be interpreted as upper bounds on this measure of asymmetry by functions which are themselves measures of asymmetry in the special case of pure states. Using measures of asymmetry that are not restricted to pure states, such as the Wigner-Yanase skew information, we obtain extensions of the Mandelstam-Tamm bound which are significantly tighter in the case of mixed states. We also clarify some confusions in the literature about coherence and asymmetry, and show that measures of coherence are a proper subset of measures of asymmetry.

  3. Measuring Asymmetry in Time-Stamped Phylogenies.

    PubMed

    Dearlove, Bethany L; Frost, Simon D W

    2015-07-01

    Previous work has shown that asymmetry in viral phylogenies may be indicative of heterogeneity in transmission, for example due to acute HIV infection or the presence of 'core groups' with higher contact rates. Hence, evidence of asymmetry may provide clues to underlying population structure, even when direct information on, for example, stage of infection or contact rates, are missing. However, current tests of phylogenetic asymmetry (a) suffer from false positives when the tips of the phylogeny are sampled at different times and (b) only test for global asymmetry, and hence suffer from false negatives when asymmetry is localised to part of a phylogeny. We present a simple permutation-based approach for testing for asymmetry in a phylogeny, where we compare the observed phylogeny with random phylogenies with the same sampling and coalescence times, to reduce the false positive rate. We also demonstrate how profiles of measures of asymmetry calculated over a range of evolutionary times in the phylogeny can be used to identify local asymmetry. In combination with different metrics of asymmetry, this combined approach offers detailed insights of how phylogenies reconstructed from real viral datasets may deviate from the simplistic assumptions of commonly used coalescent and birth-death process models.

  4. Jet vectoring through nozzle asymmetry

    NASA Astrophysics Data System (ADS)

    Roh, Chris; Rosakis, Alexandros; Gharib, Morteza

    2015-11-01

    Previously, we explored the functionality of a tri-leaflet anal valve of a dragonfly larva. We saw that the dragonfly larva is capable of controlling the three leaflets independently to asymmetrically open the nozzle. Such control resulted in vectoring of the jet in various directions. To further understand the effect of asymmetric nozzle orifice, we tested jet flow through circular asymmetric nozzles. We report the relationship between nozzle asymmetry and redirecting of the jet at various Reynolds numbers. This material is based upon work supported by the National Science Foundation under Grant No. CBET-1511414; additional support by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1144469.

  5. UV Observations of Hemispheric Asymmetry

    NASA Astrophysics Data System (ADS)

    Schaefer, R. K.; Paxton, L. J.; Wolven, B. C.; Zhang, Y.; Romeo, G.

    2015-12-01

    Asymmetry in the auroral patterns can be an important diagnostic for understanding the dynamics of solar wind interaction with the magnetosphere-ionosphere-thermosphere system (e.g., Newel and Meng, 1998; Fillingrim et al., 2005). Molecular nitrogen emission in the UV Lyman-Birge-Hopfield bands can be used to determine energy flux and electron mean energy (Sotirelis, et al, 2013) and thereby Hall and Pederson integrated conductances (Gjerloev, et al., 2014). UV imagery provided by the 4 SSUSI instruments on the Defense Meteorological Satellite Program (DMSP) F16-F19 spacecraft provide two dimensional maps of this emission at different local times. Often there are near simultaneous observations of both poles by some combination of the satellites. (see figure 1) The SSUSI auroral data products are well suited to this study, as they have the following features.: - dayglow has been subtracted on dayside aurora - electron energy flux and mean energy are pre-calculated - individual arcs have been identified through image processing. In order to intercompare data from multiple satellites, we must first ensure that the instrument calibrations are consistent. In this work we show that the instruments are consistently calibrated, and that results generated from the SSUSI data products can be trusted. Several examples of storm time asymmetries captured by the SSUSI instruments will be discussed. Fillingim, M. O., G. K. Parks, H. U. Frey, T. J. Immel, and S. B. Mende (2005), Hemispheric asymmetry of the afternoon electron aurora, Geophys. Res. Lett., 32, L03113, doi:10.1029/2004GL021635. Gjerloev, J., Schaefer, R., Paxton, L, and Zhang, Y. (2014), A comprehensive empirical model of the ionospheric conductivity derived from SSUSI/GUVI, SuperMAG and SuperDARN data, SM51G-4339, Fall 2014 AGU meeting, San Francisco. Newell, P. T., and C.-I. Meng (1988), Hemispherical asymmetry in cusp precipitation near solstices, J. Geophys. Res., 93(A4), 2643-2648, doi:10.1029/JA093iA04p02643

  6. Induction of asymmetry into homodimers.

    PubMed

    Bardsley, B; Cho, Y R; Westwell, M S; Williams, D H

    1998-01-01

    The self-regulation of biological signalling receptors via homodimerization is discussed in relation to the symmetry changes occurring when these receptors bind their target ligand. The idea of positive and negative cooperativity between dimerization and ligand binding, mediated by changes in the symmetry of the system as a source of signalling control is considered; an analogy made with the homodimerization of a glycopeptide antibiotic, ristocetin A, which displays negative cooperativity. Finally, the regulation of the bacterial aspartate receptor and the human growth hormone receptor is discussed as a function of ligand-induced asymmetry.

  7. Virtual-source diffusion approximation for enhanced near-field modeling of photon-migration in low-albedo medium.

    PubMed

    Jia, Mengyu; Chen, Xueying; Zhao, Huijuan; Cui, Shanshan; Liu, Ming; Liu, Lingling; Gao, Feng

    2015-01-26

    Most analytical methods for describing light propagation in turbid medium exhibit low effectiveness in the near-field of a collimated source. Motivated by the Charge Simulation Method in electromagnetic theory as well as the established discrete source based modeling, we herein report on an improved explicit model for a semi-infinite geometry, referred to as "Virtual Source" (VS) diffuse approximation (DA), to fit for low-albedo medium and short source-detector separation. In this model, the collimated light in the standard DA is analogously approximated as multiple isotropic point sources (VS) distributed along the incident direction. For performance enhancement, a fitting procedure between the calculated and realistic reflectances is adopted in the near-field to optimize the VS parameters (intensities and locations). To be practically applicable, an explicit 2VS-DA model is established based on close-form derivations of the VS parameters for the typical ranges of the optical parameters. This parameterized scheme is proved to inherit the mathematical simplicity of the DA approximation while considerably extending its validity in modeling the near-field photon migration in low-albedo medium. The superiority of the proposed VS-DA method to the established ones is demonstrated in comparison with Monte-Carlo simulations over wide ranges of the source-detector separation and the medium optical properties.

  8. Independent Pixel and Two Dimensional Estimates of LANDSAT-Derived Cloud Field Albedo

    NASA Technical Reports Server (NTRS)

    Chambers, L. H.; Wielicki, Bruce A.; Evans, K. F.

    1996-01-01

    A theoretical study has been conducted on the effects of cloud horizontal inhomogeneity on cloud albedo bias. A two-dimensional (2D) version of the Spherical Harmonic Discrete Ordinate Method (SHDOM) is used to estimate the albedo bias of the plane parallel (PP-IPA) and independent pixel (IPA-2D) approximations for a wide range of 2D cloud fields obtained from LANDSAT. They include single layer trade cumulus, open and closed cell broken stratocumulus, and solid stratocumulus boundary layer cloud fields over ocean. Findings are presented on a variety of averaging scales and are summarized as a function of cloud fraction, mean cloud optical depth, cloud aspect ratio, standard deviation of optical depth, and the gamma function parameter Y (a measure of the width of the optical depth distribution). Biases are found to be small for small cloud fraction or mean optical depth, where the cloud fields under study behave linearly. They are large (up to 0.20 for PP-IPA bias, -0.12 for IPA-2D bias) for large v. On a scene average basis PP-IPA bias can reach 0.30, while IPA-2D bias reaches its largest magnitude at -0.07. Biases due to horizontal transport (IPA-2D) are much smaller than PP-IPA biases but account for 20% RMS of the bias overall. Limitations of this work include the particular cloud field set used, assumptions of conservative scattering, constant cloud droplet size, no gas absorption or surface reflectance, and restriction to 2D radiative transport. The LANDSAT data used may also be affected by radiative smoothing.

  9. A test of the applicability of independent scattering to high albedo planetary regoliths

    NASA Technical Reports Server (NTRS)

    Goguen, J. D.

    1993-01-01

    We show that 'independent scattering' is a useful approximation for high albedo particles whose size and packing density are similar to typical particles in the lunar regolith. Laboratory measurements of the intensity and linear polarization of light scattered from a laboratory sample of glass spheres of know size and composition are compared to radiative transfer calculations of the same observable quantities. Mie scattering is integrated over the size distribution of the particles to determine the mean phase and polarization functions, or phase matrix, of the particle. Assuming that the particles scatter independently, the 'doubling method' is used to rigorously calculate multiple scattering in an optically thick layer of these anisotropically scattering particles. All of the major features 'predicted' in the calculated intensity (double peaks at small phase angles) and polarization (negative branch at small phase angles, large positive peak near 20 degrees phase, and small polarization elsewhere) are observed in the laboratory measurements, with good quantitative agreement indicated at phase angles less than 90 degrees. Even though the particles are supported by physical contact with each other in the sample, as are the particles in planetary regoliths, the independent scattering calculation yields a good approximation to both the intensity and polarization. The physical parameters input to the calculation are only the size distribution of the particles and their complex index of refraction (composition). Significant advantages of this approach are that the phase matrix is calculated from basic physical principles and both the intensity and polarization are determined simultaneously. This model may have broad applications to the interpretation of photometry, spectroscopy, and polarimetry of the icy regoliths of high albedo satellites. The intent of this effort is to perform a controlled experiment that tests the utility of the independent scattering assumption

  10. Impacts of Satellite-Based Snow Albedo Assimilation on Offline and Coupled Land Surface Model Simulations

    PubMed Central

    Wang, Tao; Peng, Shushi; Krinner, Gerhard; Ryder, James; Li, Yue; Dantec-Nédélec, Sarah; Ottlé, Catherine

    2015-01-01

    Seasonal snow cover in the Northern Hemisphere is the largest component of the terrestrial cryosphere and plays a major role in the climate system through strong positive feedbacks related to albedo. The snow-albedo feedback is invoked as an important cause for the polar amplification of ongoing and projected climate change, and its parameterization across models is an important source of uncertainty in climate simulations. Here, instead of developing a physical snow albedo scheme, we use a direct insertion approach to assimilate satellite-based surface albedo during the snow season (hereafter as snow albedo assimilation) into the land surface model ORCHIDEE (ORganizing Carbon and Hydrology In Dynamic EcosystEms) and assess the influences of such assimilation on offline and coupled simulations. Our results have shown that snow albedo assimilation in both ORCHIDEE and ORCHIDEE-LMDZ (a general circulation model of Laboratoire de Météorologie Dynamique) improve the simulation accuracy of mean seasonal (October throughout May) snow water equivalent over the region north of 40 degrees. The sensitivity of snow water equivalent to snow albedo assimilation is more pronounced in the coupled simulation than the offline simulation since the feedback of albedo on air temperature is allowed in ORCHIDEE-LMDZ. We have also shown that simulations of air temperature at 2 meters in ORCHIDEE-LMDZ due to snow albedo assimilation are significantly improved during the spring in particular over the eastern Siberia region. This is a result of the fact that high amounts of shortwave radiation during the spring can maximize its snow albedo feedback, which is also supported by the finding that the spatial sensitivity of temperature change to albedo change is much larger during the spring than during the autumn and winter. In addition, the radiative forcing at the top of the atmosphere induced by snow albedo assimilation during the spring is estimated to be -2.50 W m-2, the magnitude of

  11. Spring-summer albedo variations of Antarctic sea ice from 1982 to 2009

    NASA Astrophysics Data System (ADS)

    Shao, Zhu-De; Ke, Chang-Qing

    2015-06-01

    This study examined the spring-summer (November, December, January and February) albedo averages and trends using a dataset consisting of 28 years of homogenized satellite data for the entire Antarctic sea ice region and for five longitudinal sectors around Antarctica: the Weddell Sea (WS), the Indian Ocean sector (IO), the Pacific Ocean sector (PO), the Ross Sea (RS) and the Bellingshausen-Amundsen Sea (BS). Time series data of the sea ice concentrations and sea surface temperatures were used to analyse their relations to the albedo. The results indicated that the sea ice albedo increased slightly during the study period, at a rate of 0.314% per decade, over the Antarctic sea ice region. The sea ice albedos in the PO, the IO and the WS increased at rates of 2.599% per decade (confidence level 99.86%), 0.824% per decade and 0.413% per decade, respectively, and the steepest increase occurred in the PO. However, the sea ice albedo in the BS decreased at a rate of -1.617% per decade (confidence level 95.05%) and was near zero in the RS. The spring-summer average albedo over the Antarctic sea ice region was 50.24%. The highest albedo values were mainly found on the continental coast and in the WS; in contrast, the lowest albedo values were found on the outer edge of the sea ice, the RS and the Amery Ice Shelf. The average albedo in the western Antarctic sea ice region was distinctly higher than that in the east. The albedo was significantly positively correlated with sea ice concentration (SIC) and was significantly negatively correlated with sea surface temperature (SST); these scenarios held true for all five longitudinal sectors. Spatially, the higher surface albedos follow the higher SICs and lower SST patterns. The increasing albedo means that Antarctic sea ice region reflects more solar radiation and absorbs less, leading to a decrease in temperature and much snowfall on sea ice, and further resulted in an increase in albedo. Conversely, the decreasing albedo

  12. Impacts of Satellite-Based Snow Albedo Assimilation on Offline and Coupled Land Surface Model Simulations.

    PubMed

    Wang, Tao; Peng, Shushi; Krinner, Gerhard; Ryder, James; Li, Yue; Dantec-Nédélec, Sarah; Ottlé, Catherine

    2015-01-01

    Seasonal snow cover in the Northern Hemisphere is the largest component of the terrestrial cryosphere and plays a major role in the climate system through strong positive feedbacks related to albedo. The snow-albedo feedback is invoked as an important cause for the polar amplification of ongoing and projected climate change, and its parameterization across models is an important source of uncertainty in climate simulations. Here, instead of developing a physical snow albedo scheme, we use a direct insertion approach to assimilate satellite-based surface albedo during the snow season (hereafter as snow albedo assimilation) into the land surface model ORCHIDEE (ORganizing Carbon and Hydrology In Dynamic EcosystEms) and assess the influences of such assimilation on offline and coupled simulations. Our results have shown that snow albedo assimilation in both ORCHIDEE and ORCHIDEE-LMDZ (a general circulation model of Laboratoire de Météorologie Dynamique) improve the simulation accuracy of mean seasonal (October throughout May) snow water equivalent over the region north of 40 degrees. The sensitivity of snow water equivalent to snow albedo assimilation is more pronounced in the coupled simulation than the offline simulation since the feedback of albedo on air temperature is allowed in ORCHIDEE-LMDZ. We have also shown that simulations of air temperature at 2 meters in ORCHIDEE-LMDZ due to snow albedo assimilation are significantly improved during the spring in particular over the eastern Siberia region. This is a result of the fact that high amounts of shortwave radiation during the spring can maximize its snow albedo feedback, which is also supported by the finding that the spatial sensitivity of temperature change to albedo change is much larger during the spring than during the autumn and winter. In addition, the radiative forcing at the top of the atmosphere induced by snow albedo assimilation during the spring is estimated to be -2.50 W m-2, the magnitude of

  13. Implications of albedo changes following afforestation on the benefits of forests as carbon sinks

    NASA Astrophysics Data System (ADS)

    Kirschbaum, M. U. F.; Whitehead, D.; Dean, S. M.; Beets, P. N.; Shepherd, J. D.; Ausseil, A.-G. E.

    2011-12-01

    Increased carbon storage with afforestation leads to a decrease in atmospheric carbon dioxide concentration and thus decreases radiative forcing and cools the Earth. However, afforestation also changes the reflective properties of the surface vegetation from more reflective pasture to relatively less reflective forest cover. This increase in radiation absorption by the forest constitutes an increase in radiative forcing, with a warming effect. The net effect of decreased albedo and carbon storage on radiative forcing depends on the relative magnitude of these two opposing processes. We used data from an intensively studied site in New Zealand's Central North Island that has long-term, ground-based measurements of albedo over the full short-wave spectrum from a developing Pinus radiata forest. Data from this site were supplemented with satellite-derived albedo estimates from New Zealand pastures. The albedo of a well-established forest was measured as 13 % and pasture albedo as 20 %. We used these data to calculate the direct radiative forcing effect of changing albedo as the forest grew. We calculated the radiative forcing resulting from the removal of carbon from the atmosphere as a decrease in radiative forcing of -104 GJ tC-1 yr-1. We also showed that the observed change in albedo constituted a direct radiative forcing of 2759 GJ ha-1 yr-1. Thus, following afforestation, 26.5 tC ha-1 needs to be stored in a growing forest to balance the increase in radiative forcing resulting from the observed albedo change. Measurements of tree biomass and albedo were used to estimate the net change in radiative forcing as the newly planted forest grew. Albedo and carbon-storage effects were of similar magnitude for the first four to five years after tree planting, but as the stand grew older, the carbon storage effect increasingly dominated. Averaged over the whole length of the rotation, the changes in albedo negated the benefits from increased carbon storage by 17-24 %.

  14. Effects of aerosol and horizontal inhomogeneity on the broadband albedo of marine stratus: Numerical simulations

    SciTech Connect

    Duda, D.P.; Stephens, G.L.; Stevens, B.; Cotton, W.R.

    1996-12-15

    Recent estimates of the effect of increasing of anthropogenic sulfate aerosol on the radiative forcing of the atmosphere have indicated that its impact may be comparable in magnitude to the effect from increases in CO{sub 2}. Much of this impact is expected from the effects of the aerosol on cloud microphysics and the subsequent impact on cloud albedo. A solar broadband version of a 2D radiative transfer model was used to quantify the impact of enhanced aerosol concentrations and horizontal inhomogeneity on the solar broadband albedo of marine stratus. The results of the radiative transfer calculations indicated that in unbroken marine stratus clouds the net horizontal transport of photons over a domain of a few kilometers was nearly zero, and the domain-average broadband albedo computed in a 2D cross section was nearly identical to the domain average calculated from a series of independent pixel approximation (IPA) calculations of the same cross section. However, the horizontal inhomogeneity does affect the cloud albedo compared to plane-parallel approximation (PPA) computations due to the nonlinear relationship between albedo and optical depth. The reduction in cloud albedo could be related to the variability of the distribution of log (cloud optical depth). These results extend the finding of Cahalan et al. to broadband solar albedos in a more realistic cloud model and suggest that accurate computation of domain-averaged broadband albedos in unbroken (or nearly unbroken) marine stratus can be made using IPA calculations with 1D radiative transfer models. Computations of the mean albedo over portions of the 3D RAMS domain show the relative increase in cloud albedo due to a 67% increase in the boundary-layer average CCN concentration was between 6% and 9%. The effects of cloud inhomogeneity on the broadband albedo as measured from the PPA bias ranged from 3% to 5%. 25 refs., 8 figs., 4 tabs.

  15. Quantifying the missing link between forest albedo and productivity in the boreal zone

    NASA Astrophysics Data System (ADS)

    Hovi, Aarne; Liang, Jingjing; Korhonen, Lauri; Kobayashi, Hideki; Rautiainen, Miina

    2016-11-01

    Albedo and fraction of absorbed photosynthetically active radiation (FAPAR) determine the shortwave radiation balance and productivity of forests. Currently, the physical link between forest albedo and productivity is poorly understood, yet it is crucial for designing optimal forest management strategies for mitigating climate change. We investigated the relationships between boreal forest structure, albedo and FAPAR using a radiative transfer model called Forest Reflectance and Transmittance model FRT and extensive forest inventory data sets ranging from southern boreal forests to the northern tree line in Finland and Alaska (N = 1086 plots). The forests in the study areas vary widely in structure, species composition, and human interference, from intensively managed in Finland to natural growth in Alaska. We show that FAPAR of tree canopies (FAPARCAN) and albedo are tightly linked in boreal coniferous forests, but the relationship is weaker if the forest has broadleaved admixture, or if canopies have low leaf area and the composition of forest floor varies. Furthermore, the functional shape of the relationship between albedo and FAPARCAN depends on the angular distribution of incoming solar irradiance. We also show that forest floor can contribute to over 50 % of albedo or total ecosystem FAPAR. Based on our simulations, forest albedos can vary notably across the biome. Because of larger proportions of broadleaved trees, the studied plots in Alaska had higher albedo (0.141-0.184) than those in Finland (0.136-0.171) even though the albedo of pure coniferous forests was lower in Alaska. Our results reveal that variation in solar angle will need to be accounted for when evaluating climate effects of forest management in different latitudes. Furthermore, increasing the proportion of broadleaved trees in coniferous forests is the most important means of maximizing albedo without compromising productivity: based on our findings the potential of controlling forest

  16. Monte Carlo simulations of spectral albedo for artificial snowpacks composed of spherical and nonspherical particles.

    PubMed

    Tanikawa, Tomonori; Aoki, Teruo; Hori, Masahiro; Hachikubo, Akihiro; Abe, Osamu; Aniya, Masamu

    2006-07-20

    The optical properties of snowpacks composed of spherical and nonspherical particles artificially prepared in a cold laboratory are investigated by measuring spectral albedos. The measured spectral albedo in the spectral region lambda=0.35-2.5 microm is compared with the theoretically calculated albedo, for which a Monte Carlo radiative transfer model is employed for multiple scattering combined with the Mie theory and the ray-tracing technique for single scattering by snow particles. Since the spherical particles are a little aggregate, the effects of a cluster of the spheres on snow albedo are examined using a generalized multiparticle Mie-solution model [Appl. Opt. 34, 4573 (1995); J. Quant. Spectrosc. Radiat. Transf. 79-80, 1121 (2003)]. The snow albedo of a cluster of the spheres can be represented with that of the singe sphere slightly larger than its component of the cluster in case of small grains. The observed albedos for the spherical snow particles agree with the theoretically calculated ones for the snow grain size measured in the snow pit work. The snow albedos for the nonspherical particles, which were dendrites, are influenced by the branch width and the branch length, based on a comparison of the theoretically calculated albedo by using circular cylindrical snow particles and the observed albedo. The snow albedo in the near-infrared region depends on the branch width only when the branch length is sufficiently greater than the branch width. The comparison between the spherical and nonspherical snow particles indicates that the spectral albedo of the nonspherical particles can be represented by using an equal volume-area ratio sphere.

  17. Mineralogical Variations Among High Albedo E-Type Asteroids: Implications for Asteroid Igneous Processes

    NASA Technical Reports Server (NTRS)

    Gaffey, Michael J.; Kelley, Michael S.

    2004-01-01

    The link between the E-type asteroids and the enstatite achondrites (aubrites) was first proposed for the original E-asteroid, 44 Nysa. The association was based on the high albedos and the featureless spectra shared by the E-asteroids and the aubrites. Among the plausible geologic and meteoritic materials, only enstatite (the magnesium end-member of the pyroxene solid solution series) is sufficiently abundant to comprise asteroid-sized bodies. However, the presence of a weak 0.89 m absorption feature in the spectrum of 44 Nysa indicates that its pyroxene contains a small amount of Fe(2+) but still substantially more than any aubrite present in the meteorite collection. The original E-class was defined based on its high albedo and flat to slightly reddish spectrum. In the absence of albedo data, the E-type was degenerate with the M- and P-types, and together these were designated as X-types. Recently, a taxonomy has been proposed to identify E-types in the absence of albedo data. In this newer classification system three subdivisions of the X-type have been proposed, including Xc, Xe and Xk. Of nine albedo-defined E-types [d], this newer non-albedo based taxonomy produced the following classifications: X-1 asteroid; Xc-2 asteroids; Xe-5 asteroids; and Xk-1 asteroid. Although the Xe subtype includes the largest number of albedo-defined E-types, most of the remaining 24 Xe-types can be excluded based on their low measured IRAS albedos, ranging from 0.116 to 0.329, which are below the lower albedo limit of the E-class (0.34) and substantially below that of the lowest albedo an actual E-type asteroid (0.41). The present discussion will be limited to unambiguous E-type asteroids determined on albedo criteria.

  18. Fluctuating asymmetry and psychometric intelligence.

    PubMed Central

    Furlow, F B; Armijo-Prewitt, T; Gangestad, S W; Thornhill, R

    1997-01-01

    Little is known about the genetic nature of human psychometric intelligence (IQ), but it is widely assumed that IQ's heritability is at loci for intelligence per se. We present evidence consistent with a hypothesis that interindividual IQ differences are partly due to heritable vulnerabilities to environmental sources of developmental stress, an indirect genetic mechanism for the heritability of IQ. Using fluctuating asymmetry (FA) of the body (the asymmetry resulting from errors in the development of normally symmetrical bilateral traits under stressful conditions), we estimated the relative developmental instability of 112 undergraduates and administered to them Cattell's culture fair intelligence test (CFIT). A subsequent replication on 128 students was performed. In both samples, FA correlated negatively and significantly with CFIT scores. We propose two non-mutually exclusive physiological explanations for this correlation. First, external body FA may correlate negatively with the developmental integrity of the brain. Second, individual energy budget allocations and/or low metabolic efficiency in high-FA individuals may lower IQ scores. We review the data on IQ in light of our findings and conclude that improving developmental quality may increase average IQ in future generations. PMID:9265189

  19. Strangeness asymmetry in the proton

    NASA Astrophysics Data System (ADS)

    Alberg, Mary

    2015-04-01

    Strangeness asymmetry in the proton may arise from fluctuations of the proton into meson-baryon pairs. The leading contributions to proton strangeness are from the KΛ , KΣ , K* Λ and K* Σ states. We use a Fock state expansion of the proton in terms of these pairs to represent the strange meson cloud. We determine the strangeness distributions of the proton in a hybrid convolution model, in which the fluctuations are represented either by light-cone wave functions or meson-baryon splitting functions. For the parton distributions of the s(s) quarks in the bare baryons(mesons) of the Fock states, we use light cone wave functions or our statistical model, which expands the bare hadrons in terms of quark-gluon states. The momentum distributions of the s and s quarks in each Fock state differ because they are constituents of different hadrons. We present our results for proton strangeness asymmetry, and compare them to NuTeV and to global parton distributions. This research has been supported in part by NSF Award 1205686.

  20. Asymmetry in the epithalamus of vertebrates

    PubMed Central

    L. CONCHA, MIGUEL; W. WILSON, STEPHEN

    2001-01-01

    The epithalamus is a major subdivision of the diencephalon constituted by the habenular nuclei and pineal complex. Structural asymmetries in this region are widespread amongst vertebrates and involve differences in size, neuronal organisation, neurochemistry and connectivity. In species that possess a photoreceptive parapineal organ, this structure projects asymmetrically to the left habenula, and in teleosts it is also situated on the left side of the brain. Asymmetries in size between the left and right sides of the habenula are often associated with asymmetries in neuronal organisation, although these two types of asymmetry follow different evolutionary courses. While the former is more conspicuous in fishes (with the exception of teleosts), asymmetries in neuronal organisation are more robust in amphibia and reptiles. Connectivity of the parapineal organ with the left habenula is not always coupled with asymmetries in habenular size and/or neuronal organisation suggesting that, at least in some species, assignment of parapineal and habenular asymmetries may be independent events. The evolutionary origins of epithalamic structures are uncertain but asymmetry in this region is likely to have existed at the origin of the vertebrate, perhaps even the chordate, lineage. In at least some extant vertebrate species, epithalamic asymmetries are established early in development, suggesting a genetic regulation of asymmetry. In some cases, epigenetic factors such as hormones also influence the development of sexually dimorphic habenular asymmetries. Although the genetic and developmental mechanisms by which neuroanatomical asymmetries are established remain obscure, some clues regarding the mechanisms underlying laterality decisions have recently come from studies in zebrafish. The Nodal signalling pathway regulates laterality by biasing an otherwise stochastic laterality decision to the left side of the epithalamus. This genetic mechanism ensures a consistency of

  1. Scintillation Monitoring Using Asymmetry Index

    NASA Astrophysics Data System (ADS)

    Shaikh, Muhammad Mubasshir; Mahrous, Ayman; Abdallah, Amr; Notarpietro, Riccardo

    Variation in electron density can have significant effect on GNSS signals in terms of propagation delay. Ionospheric scintillation can be caused by rapid change of such delay, specifically, when they last for a longer period of time. Ionospheric irregularities that account for scintillation may vary significantly in spatial range and drift with the background plasma at speeds of 45 to 130 m/sec. These patchy irregularities may occur several times during night, e.g. in equatorial region, with the patches move through the ray paths of the GNSS satellite signals. These irregularities are often characterized as either ‘large scale’ (which can be as large as several hundred km in East-West direction and many times that in the North-South direction) or ‘small scale’ (which can be as small as 1m). These small scale irregularities are regarded as the main cause of scintillation [1,2]. In normal solar activity conditions, the mid-latitude ionosphere is not much disturbed. However, during severe magnetic storms, the aurora oval extends towards the equator and the equator anomaly region may stretched towards poles extending the scintillation phenomena more typically associated with those regions into mid-latitudes. In such stormy conditions, the predicted TEC may deviate largely from the true value of the TEC both at low and mid-latitudes due to which GNSS applications may be strongly degraded. This work is an attempt to analyze ionospheric scintillation (S4 index) using ionospheric asymmetry index [3]. The asymmetry index is based on trans-ionospheric propagation between GPS and LEO satellites in a radio occultation (RO) scenario, using background ionospheric data provided by MIDAS [4]. We attempted to simulate one of the recent geomagnetic storms (NOAA scale G4) occurred over low/mid-latitudes. The storm started on 26 September 2011 at UT 18:00 and lasted until early hours of 27 September 2011. The scintillation data for the storm was taken from an ionospheric

  2. Impurities in Snow: Effects on Spectral Albedo of Prairie Snowpacks

    NASA Astrophysics Data System (ADS)

    Morris, J. N.; Klein, A. G.

    2007-12-01

    While extensive research on soot in snow has been done in the Polar Regions, there remains a lack of observations addressing the effect of soot on snow albedo in North American prairie snowpacks which causes uncertainty to the overall global effect that soot in snow has on climate. Measurements of snow impurities in freshly fallen prairie snowpacks in northwestern Iowa and central Texas collected from February 28 - March 5, 2007 and April 6, 2007, respectively. Two significant snowfall events occurred in northwestern Iowa during the study; the second snowfall event produced the most severe blizzard conditions in northwestern Iowa in the last thirty years. An unusual snowfall event in central Texas offered a unique sampling opportunity Several types of sites were sampled during the field campaign; this includes: frozen lakes with minimal human impact, agricultural fields impacted by agricultural dust, and human impacted sample sites. At twelve sites in northwestern Iowa samples were collected on multiple days and for both snow events to examine changes in snow impurities over time. At all site locations snow samples, temperature, density, and grain size were recorded. Snow reflectance and snow radiance was collected at a subset of the sites with an ASD VNIR Spectroradiometer (350 - 1500 nm). Snow impurities of light-absorbing particulate matter were measured by filtering the meltwater through a nuclepore 0.4 micrometer filter. Impurity concentration was determined by comparing the filters against a set of standards. A photometer will provide a more exact determination of snow impurities in the near future. Preliminary soot observations indicate prairie snow pack concentrations ranging from 1 ngC/g to 236 ngC/g with an average of 61.4 ngC/g. These measurements are within range of previously published values in the Arctic and can lower snow albedo. Differences in soot concentrations were observed between the two Iowa snowfall events. Impurity concentrations measured

  3. Dark matter, shared asymmetries, and galactic gamma ray signals

    SciTech Connect

    Fonseca, Nayara; Necib, Lina; Thaler, Jesse E-mail: lnecib@mit.edu

    2016-02-01

    We introduce a novel dark matter scenario where the visible sector and the dark sector share a common asymmetry. The two sectors are connected through an unstable mediator with baryon number one, allowing the standard model baryon asymmetry to be shared with dark matter via semi-annihilation. The present-day abundance of dark matter is then set by thermal freeze-out of this semi-annihilation process, yielding an asymmetric version of the WIMP miracle as well as promising signals for indirect detection experiments. As a proof of concept, we find a viable region of parameter space consistent with the observed Fermi excess of GeV gamma rays from the galactic center.

  4. ALBEDO MODELS FOR SNOW AND ICE ON A FRESHWATER LAKE. (R824801)

    EPA Science Inventory

    Abstract

    Snow and ice albedo measurements were taken over a freshwater lake in Minnesota for three months during the winter of 1996¯1997 for use in a winter lake water quality model. The mean albedo of new snow was measured as 0.83±0.028, while the...

  5. Time-variable Earth's albedo model characteristics and applications to satellite sampling errors

    NASA Technical Reports Server (NTRS)

    Bartman, F. L.

    1981-01-01

    Characteristics of the time variable Earth albedo model are described. With the cloud cover multiplying factor adjusted to produce a global annual average albedo of 30.3, the global annual average cloud cover is 45.5 percent. Global annual average sunlit cloud cover is 48.5 percent; nighttime cloud cover is 42.7 percent. Month-to-month global average albedo is almost sinusoidal with maxima in June and December and minima in April and October. Month-to-month variation of sunlit cloud cover is similar, but not in all details. The diurnal variation of global albedo is greatest from November to March; the corresponding variation of sunlit cloud cover is greatest from May to October. Annual average zonal albedos and monthly average zonal albedos are in good agreement with satellite-measured values, with notable differences in the polar regions in some months and at 15 S. The albedo of some 10 deg by 10 deg. areas of the Earth versus zenith angle are described. Satellite albedo measurement sampling effects are described in local time and in Greenwich mean time.

  6. MAIN BELT ASTEROIDS WITH WISE/NEOWISE. I. PRELIMINARY ALBEDOS AND DIAMETERS

    SciTech Connect

    Masiero, Joseph R.; Mainzer, A. K.; Bauer, J. M.; Eisenhardt, P. R. M.; DeBaun, E.; Elsbury, D.; Gautier, T. IV; Gomillion, S.; Wilkins, A.; Cutri, R. M.; Dailey, J.; McMillan, R. S.; Spahr, T. B.; Skrutskie, M. F.; Tholen, D.; Walker, R. G.; Wright, E. L.

    2011-11-10

    We present initial results from the Wide-field Infrared Survey Explorer (WISE), a four-band all-sky thermal infrared survey that produces data well suited for measuring the physical properties of asteroids, and the NEOWISE enhancement to the WISE mission allowing for detailed study of solar system objects. Using a NEATM thermal model fitting routine, we compute diameters for over 100,000 Main Belt asteroids from their IR thermal flux, with errors better than 10%. We then incorporate literature values of visible measurements (in the form of the H absolute magnitude) to determine albedos. Using these data we investigate the albedo and diameter distributions of the Main Belt. As observed previously, we find a change in the average albedo when comparing the inner, middle, and outer portions of the Main Belt. We also confirm that the albedo distribution of each region is strongly bimodal. We observe groupings of objects with similar albedos in regions of the Main Belt associated with dynamical breakup families. Asteroid families typically show a characteristic albedo for all members, but there are notable exceptions to this. This paper is the first look at the Main Belt asteroids in the WISE data, and only represents the preliminary, observed raw size, and albedo distributions for the populations considered. These distributions are subject to survey biases inherent to the NEOWISE data set and cannot yet be interpreted as describing the true populations; the debiased size and albedo distributions will be the subject of the next paper in this series.

  7. Main-belt asteroids with WISE/NEOWISE: Near-infrared albedos

    SciTech Connect

    Masiero, Joseph R.; Mainzer, A. K.; Nugent, C. R.; Bauer, J. M.; Stevenson, R.; Sonnett, S.

    2014-08-20

    We present revised near-infrared albedo fits of 2835 main-belt asteroids observed by WISE/NEOWISE over the course of its fully cryogenic survey in 2010. These fits are derived from reflected-light near-infrared images taken simultaneously with thermal emission measurements, allowing for more accurate measurements of the near-infrared albedos than is possible for visible albedo measurements. Because our sample requires reflected light measurements, it undersamples small, low-albedo asteroids, as well as those with blue spectral slopes across the wavelengths investigated. We find that the main belt separates into three distinct groups of 6%, 16%, and 40% reflectance at 3.4 μm. Conversely, the 4.6 μm albedo distribution spans the full range of possible values with no clear grouping. Asteroid families show a narrow distribution of 3.4 μm albedos within each family that map to one of the three observed groupings, with the (221) Eos family being the sole family associated with the 16% reflectance 3.4 μm albedo group. We show that near-infrared albedos derived from simultaneous thermal emission and reflected light measurements are important indicators of asteroid taxonomy and can identify interesting targets for spectroscopic follow-up.

  8. Robust albedo estimation from a facial image with cast shadow under general unknown lighting.

    PubMed

    Suh, Sungho; Lee, Minsik; Choi, Chong-Ho

    2013-01-01

    Albedo estimation from a facial image is crucial for various computer vision tasks, such as 3-D morphable-model fitting, shape recovery, and illumination-invariant face recognition, but the currently available methods do not give good estimation results. Most methods ignore the influence of cast shadows and require a statistical model to obtain facial albedo. This paper describes a method for albedo estimation that makes combined use of image intensity and facial depth information for an image with cast shadows and general unknown light. In order to estimate the albedo map of a face, we formulate the albedo estimation problem as a linear programming problem that minimizes intensity error under the assumption that the surface of the face has constant albedo. Since the solution thus obtained has significant errors in certain parts of the facial image, the albedo estimate needs to be compensated. We minimize the mean square error of albedo under the assumption that the surface normals, which are calculated from the facial depth information, are corrupted with noise. The proposed method is simple and the experimental results show that this method gives better estimates than other methods.

  9. Intercomparison Between in situ and AVHRR Polar Pathfinder-Derived Surface Albedo over Greenland

    NASA Technical Reports Server (NTRS)

    Stroeve, Julienne C.; Box, Jason E.; Fowler, Charles; Haran, Terence; Key, Jeffery

    2001-01-01

    The Advanced Very High Resolution (AVHRR) Polar Pathfinder Data (APP) provides the first long time series of consistent, calibrated surface albedo and surface temperature data for the polar regions. Validations of these products have consisted of individual studies that analyzed algorithm performance for limited regions and or time periods. This paper reports on comparisons made between the APP-derived surface albedo and that measured at fourteen automatic weather stations (AWS) around the Greenland ice sheet from January 1997 to August 1998. Results show that satellite-derived surface albedo values are on average 10% less than those measured by the AWS stations. However, the station measurements tend to be biased high by about 4% and thus the differences in absolute albedo may be less (e.g. 6%). In regions of the ice sheet where the albedo variability is small, such as the dry snow facies, the APP albedo uncertainty exceeds the natural variability. Further work is needed to improve the absolute accuracy of the APP-derived surface albedo. Even so, the data provide temporally and spatially consistent estimates of the Greenland ice sheet albedo.

  10. The evolution and genetics of cerebral asymmetry

    PubMed Central

    Corballis, Michael C.

    2008-01-01

    Handedness and cerebral asymmetry are commonly assumed to be uniquely human, and even defining characteristics of our species. This is increasingly refuted by the evidence of behavioural asymmetries in non-human species. Although complex manual skill and language are indeed unique to our species and are represented asymmetrically in the brain, some non-human asymmetries appear to be precursors, and others are shared between humans and non-humans. In all behavioural and cerebral asymmetries so far investigated, a minority of individuals reverse or negate the dominant asymmetry, suggesting that such asymmetries are best understood in the context of the overriding bilateral symmetry of the brain and body, and a trade-off between the relative advantages and disadvantages of symmetry and asymmetry. Genetic models of handedness, for example, typically postulate a gene with two alleles, one disposing towards right-handedness and the other imposing no directional influence. There is as yet no convincing evidence as to the location of this putative gene, suggesting that several genes may be involved, or that the gene may be monomorphic with variations due to environmental or epigenetic influences. Nevertheless, it is suggested that, in behavioural, neurological and evolutionary terms, it may be more profitable to examine the degree rather than the direction of asymmetry. PMID:19064358

  11. Right-Left Asymmetries in the Brain

    ERIC Educational Resources Information Center

    Galaburda, Albert M.; And Others

    1978-01-01

    Reports on structural asymmetrics between the hemispheres which are found in the human brain. Auditory region and Sylvian Fissure asymmetry have also been observed in the fetus and in other primates. Describes research which has correlated asymmetries with hand preference, certain childhood learning disabilities and some dementing illnesses of…

  12. Atypical Alpha Asymmetry in Adults with ADHD

    ERIC Educational Resources Information Center

    Hale, T. Sigi; Smalley, Susan L.; Hanada, Grant; Macion, James; McCracken, James T.; McGough, James J.; Loo, Sandra K.

    2009-01-01

    Introduction: A growing body of literature suggests atypical cerebral asymmetry and interhemispheric interaction in ADHD. A common means of assessing lateralized brain function in clinical populations has been to examine the relative proportion of EEG alpha activity (8-12 Hz) in each hemisphere (i.e., alpha asymmetry). Increased rightward alpha…

  13. Asymmetry and Performance: Toward a Neurodevelopmental Theory

    ERIC Educational Resources Information Center

    Boles, David B.; Barth, Joan M.; Merrill, Edward C.

    2008-01-01

    Hemispheric asymmetry implies the existence of developmental influences that affect one hemisphere more than the other. However, those influences are poorly understood. One simple view is that asymmetry may exist because of a relationship between a mental process' degree of lateralization and how well it functions. Data scaling issues have largely…

  14. Joint AOT-Single Scattering Albedo Retrieval in Algorithm MAIAC

    NASA Astrophysics Data System (ADS)

    Lyapustin, A.

    2015-12-01

    Multi-Angle Implementation of Atmospheric Correction (MAIAC) is a new algorithm which uses time series analysis and processing of groups of pixels for advanced cloud detection and retrieval of aerosol and surface bidirectional reflectance properties. MAIAC C6+ re-processing of MODIS data record, scheduled to begin in November 2015, will create a suite of products MCD19. Due to high 1km resolution, MAIAC provides information about fine scale aerosol variability required in different applications such as urban air quality analysis. During the past year, we developed a new MAIAC capability to retrieve Single Scattering Albedo (SSA) from MODIS by adapting OMI heritage approach of O. Torres. We will describe MAIAC retrieval approach, AERONET AOT and SSA validation for different world biomass burning regions, and will compare MAIAC results with other sensors.

  15. Performance of an albedo collecting bifacial flat module

    SciTech Connect

    Sala, G.; Calleja, M.J.; Eguren, J.; Luque, A.; Romero, S.L.

    1984-05-01

    Bifacial photovoltaic modules have been recently developed and are now commercially available. These modules are able to collect the light reaching them from the surroundings not only on their front side, but also on their back side. This paper presents the performance on the industrially manufactured bifacial modules measured in outdoor conditions. The authors have found a very significative increase in their output power when the albedo light, diffusively reflected by the white painted floor, is collected on the back side of the module at any given condition. A model to calculate the available energy incident on the back is presented, experimentally validated and used to calculate the overall gain of collected energy. The authors obtained an increase of 57% for an array of infinite modules when the reflectivity of the floor is 0.75.

  16. The albedos of Pluto and Charon - Wavelength dependence

    NASA Technical Reports Server (NTRS)

    Marcialis, Robert L.; Lebofsky, Larry A.; Disanti, Michael A.; Fink, Uwe; Tedesco, Edward F.; Africano, John

    1992-01-01

    The March 3, 1987 occultation of Charon by Pluto was monitored simultaneously with three telescopes. Each site covered a distinct wavelength interval with the total range spanning 0.44-2.4 microns. Observing the same event ensures an identical sun-Pluto-earth geometry for all three sites, and minimizes the assumptions which must be made to combine results. This spectrophotometry is used to derive the individual geometric albedos of Pluto and Charon over a factor of at least 5 in wavelength. Combining the results with those of Binzel (1988) improved (B - V) color estimates (on the 'Johnson Pluto' system) are obtained for the components of the system at rotational phase 0.75: (Pluto + Charon) = 0.843 +/- 0.006; Pluto alone = 0.866 +/- 0.007; and Charon alone = 0.702 +/- 0.010.

  17. Contribution to polar albedo from a mesospheric aerosol layer

    NASA Technical Reports Server (NTRS)

    Hummel, J. R.

    1977-01-01

    An examination is made of the impact of a layer of particulate matter, assumed to be ice crystals, on the albedo of the polar region. The model is time dependent, includes the growth of the layer, and incorporates the diffuse nature of radiation reflected from the surface and atmosphere. Although the magnitude of the effect is about an order of magnitude less than previous results, the impact is one of heating instead of cooling. It is also shown that ignoring the diffuse nature of the radiation reflected from the underlying earth-atmosphere system, as has been done in many previous simple models, can result in overestimation of the climatological impact of aerosols in sign and magnitude by a factor of up to 4-6.

  18. Correlating Pluto's Albedo Distribution to Long Term Insolation Patterns

    NASA Astrophysics Data System (ADS)

    Earle, Alissa M.; Binzel, Richard P.; Stern, S. Alan; Young, Leslie A.; Buratti, Bonnie J.; Ennico, Kimberly; Grundy, Will M.; Olkin, Catherine B.; Spencer, John R.; Weaver, Hal A.

    2015-11-01

    NASA's New Horizons' reconnaissance of the Pluto system has revealed striking albedo contrasts from polar to equatorial latitudes on Pluto, as well as sharp boundaries for longitudinal variations. These contrasts suggest Pluto undergoes dynamic evolution that drives the redistribution of volatiles. Using the New Horizons results as a template, in this talk we will explore the volatile migration process driven seasonally on Pluto considering multiple timescales. These timescales include the current orbit (248 years) as well as the timescales for obliquity precession (amplitude of 23 degrees over 3 Myrs) and regression of the orbital longitude of perihelion (3.7 Myrs). We will build upon the long-term insolation history model described by Earle and Binzel (2015, Icarus 250, 405-412) with the goal of identifying the most critical timescales that drive the features observed in Pluto’s current post-perihelion epoch. This work was supported by the NASA New Horizons Project.

  19. A digital file of the lunar normal Albedo

    USGS Publications Warehouse

    Wildey, R.L.

    1977-01-01

    A digital file of the normal albedo of the Moon has been produced at a resolution of about 1/550 of a lunar diameter (about 6.3 km). The file was produced from five photographs taken with the 61-cm reflector of the Northern Arizona University Astrophysical Observatory. No mosaicking was necessary. Spatial control is selenodetic rather than landmark-morphologic. Photometric control is provided through a combination of electrography and regular photoelectric photometry. Pixel photometric function corrections are employed. The file was provided as data base for the Lunar Consortium. Brief discussion of the scientific implications of the frequency histogram is offered, and the negligibility of lunar limb darkening below e{open} = 77?? is affirmed. It is specifically desired not to withhold these data from publication while more significant and detailed scientific interpretation is carried on. ?? 1977 D. Reidel Publishing Company, Dordrecht-Holland.

  20. Color and albedo heterogeneity of Vesta from Dawn.

    PubMed

    Reddy, Vishnu; Nathues, Andreas; Le Corre, Lucille; Sierks, Holger; Li, Jian-Yang; Gaskell, Robert; McCoy, Timothy; Beck, Andrew W; Schröder, Stefan E; Pieters, Carle M; Becker, Kris J; Buratti, Bonnie J; Denevi, Brett; Blewett, David T; Christensen, Ulrich; Gaffey, Michael J; Gutierrez-Marques, Pablo; Hicks, Michael; Keller, Horst Uwe; Maue, Thorsten; Mottola, Stefano; McFadden, Lucy A; McSween, Harry Y; Mittlefehldt, David; O'Brien, David P; Raymond, Carol; Russell, Christopher

    2012-05-11

    Multispectral images (0.44 to 0.98 μm) of asteroid (4) Vesta obtained by the Dawn Framing Cameras reveal global color variations that uncover and help understand the north-south hemispherical dichotomy. The signature of deep lithologies excavated during the formation of the Rheasilvia basin on the south pole has been preserved on the surface. Color variations (band depth, spectral slope, and eucrite-diogenite abundance) clearly correlate with distinct compositional units. Vesta displays the greatest variation of geometric albedo (0.10 to 0.67) of any asteroid yet observed. Four distinct color units are recognized that chronicle processes--including impact excavation, mass wasting, and space weathering--that shaped the asteroid's surface. Vesta's color and photometric diversity are indicative of its status as a preserved, differentiated protoplanet.

  1. The Albedo Dichotomy of Iapetus Measured at UV Wavelengths

    NASA Technical Reports Server (NTRS)

    Hendrix, Amanda R.; Hansen, Candice J.

    2007-01-01

    The dramatic hemispheric dichotomy in albedo displayed by Saturn's moon Iapetus has intrigued astronomers for centuries. Here we report on far-ultraviolet observations of Iapetus' bright and dark terrains from Cassini. We compare the reflectance spectra of Iapetus's dark terrain, Hyperion and Phoebe and find that both Phoebe and Hyperion are richer in water ice than Iapetus' dark terrain. Spectra of the lowest latitudes of the dark terrain display the diagnostic water ice absorption feature; water ice amounts increase within the dark material away from the apex (at 90 deg W longitude, the center of the dark leading hemisphere), consistent with thermal segregation of water ice. The water ice in the darkest, warmest low latitude regions is not expected to be stable and may be a sign of ongoing or recent emplacement of the dark material from an exogenic source.

  2. Global Monitoring of Martian Surface Albedo Changes from Orbital Observations

    NASA Astrophysics Data System (ADS)

    Geissler, P.; Enga, M.; Mukherjee, P.

    2013-12-01

    Martian surface changes were first observed from orbit during the Mariner 9 and Viking Orbiter missions. They were found to be caused by eolian processes, produced by deposition of dust during regional and global dust storms and subsequent darkening of the surface through erosion and transportation of dust and sand. The albedo changes accumulated in the 20 years between Viking and Mars Global Surveyor were sufficient to alter the global circulation of winds and the climate of Mars according to model calculations (Fenton et al., Nature 2007), but little was known about the timing or frequency of the changes. Since 1999, we have had the benefit of continuous monitoring by a series of orbiting spacecraft that continues today with Mars Reconnaissance Orbiter, Mars Odyssey, and Mars Express. Daily synoptic observations enable us to determine whether the surface albedo changes are gradual or episodic in nature and to record the seasons that the changes take place. High resolution images of surface morphology and atmospheric phenomena help identify the physical mechanisms responsible for the changes. From these data, we hope to learn the combinations of atmospheric conditions and sediment properties that produce surface changes on Mars and possibly predict when they will take place in the future. Martian surface changes are particularly conspicuous in low albedo terrain, where even a thin layer of bright dust brightens the surface drastically. Equatorial dark areas are repeatedly coated and recoated by dust, which is later shed from the surface by a variety of mechanisms. An example is Syrtis Major, suddenly buried in bright dust by the global dust storm of 2001. Persistent easterly winds blew much of the dust cover away over the course of the next Martian year, but episodic changes continue today, particularly during southern summer when regional dust storms are rife. Another such region is Solis Planum, south of the Valles Marineris, where changes take place

  3. The influence of inter-annually varying albedo on regional climate and drought

    NASA Astrophysics Data System (ADS)

    Meng, X. H.; Evans, J. P.; McCabe, M. F.

    2014-02-01

    Albedo plays an important role in land-atmosphere interactions and local climate. This study presents the impact on simulating regional climate, and the evolution of a drought, when using the default climatological albedo as is usually done in regional climate modelling, or using the actual observed albedo which is rarely done. Here, time-varying satellite derived albedo data is used to update the lower boundary condition of the Weather Research and Forecasting regional climate model in order to investigate the influence of observed albedo on regional climate simulations and also potential changes to land-atmosphere feedback over south-east Australia. During the study period from 2000 to 2008, observations show that albedo increased with an increasingly negative precipitation anomaly, though it lagged precipitation by several months. Compared to in-situ observations, using satellite observed albedo instead of the default climatological albedo provided an improvement in the simulated seasonal mean air temperature. In terms of precipitation, both simulations reproduced the drought that occurred from 2002 through 2006. Using the observed albedo produced a drier simulation overall. During the onset of the 2002 drought, albedo changes enhanced the precipitation reduction by 20 % on average, over locations where it was active. The area experiencing drought increased 6.3 % due to the albedo changes. Two mechanisms for albedo changes to impact land-atmosphere drought feedback are investigated. One accounts for the increased albedo, leading to reduced turbulent heat flux and an associated decrease of moist static energy density in the planetary boundary layer; the other considers that enhanced local radiative heating, due to the drought, favours a deeper planetary boundary layer, subsequently decreasing the moist static energy density through entrainment of the free atmosphere. Analysis shows that drought related large-scale changes in the regional climate favour a

  4. The influence of inter-annually varying albedo on regional climate and drought

    NASA Astrophysics Data System (ADS)

    Meng, X. H.; Evans, J. P.; McCabe, M. F.

    2013-05-01

    Albedo plays an important role in land-atmosphere interactions and local climate. This study presents the impact on simulating regional climate, and the evolution of a drought, when using the default climatological albedo as is usually done in regional climate modelling, or using the actual observed albedo which is rarely done. Here, time-varying satellite derived albedo data is used to update the lower boundary condition of the Weather Research and Forecasting regional climate model in order to investigate the influence of observed albedo on regional climate simulations and also potential changes to land-atmosphere feedback over south-east Australia. During the study period from 2000 to 2008, observations show that albedo increased with an increasingly negative precipitation anomaly, though it lagged precipitation by several months. Compared to in-situ observations, using satellite observed albedo instead of the default climatological albedo provided an improvement in the simulated seasonal mean air temperature. In terms of precipitation, both simulations reproduced the drought that occurred from 2002 through 2006. Using the observed albedo produced a drier simulation overall. During the onset of the 2002 drought, albedo changes enhanced the precipitation reduction by 20 % on average, over locations where it was active. The area experiencing drought increased 6.3 % due to the albedo changes. Two mechanisms for albedo changes to impact land-atmosphere drought feedback are investigated. One accounts for the increased albedo, leading to reduced turbulent heat flux and an associated decrease of moist static energy density in the planetary boundary layer; the other considers that enhanced local radiative heating, due to the drought, favours a deeper planetary boundary layer, subsequently decreasing the moist static energy density through entrainment of the free atmosphere. Analysis shows that drought related large-scale changes in the regional climate favour a

  5. Water Ice Albedo Variations on the Martian Northern Polar Cap

    NASA Technical Reports Server (NTRS)

    Hale, A. S.; Bass, D. S.; Tamppari, L. K.

    2003-01-01

    The Viking Orbiters determined that the surface of Mars northern residual cap is water ice. Many researchers have related observed atmospheric water vapor abundances to seasonal exchange between reservoirs such as the polar caps, but the extent to which the exchange between the surface and the atmosphere remains uncertain. Early studies of the ice coverage and albedo of the northern residual Martian polar cap using Mariner 9 and Viking images reported that there were substantial internannual differences in ice deposition on the polar cap, a result which suggested a highly variable Martian climate. However, some of the data used in these studies were obtained at differing values of heliocentric solar longitude (L(sub s)). Reevaluation of this dataset indicated that the residual cap undergoes seasonal brightening throughout the summer, and indicated that this process repeats from year to year. In this study we continue to compare Mariner 9 and Viking Orbiter imaging observations and thermal data of the north residual polar cap to data acquired with Mars Global Surveyor s Mars Orbiter Camera (MOC) instrument. In the current study, our goal is to examine all released data from MGS MOC in the northern summer season, along with applicable TES data in order to better understand the albedo variations in the northern summer and their implications on water transport. To date, work has focused primarily on the MOC dataset. In 1999, data acquisition of the northern polar regions began at L(sub s) = 107, although there was little north polar data acquired from L(sub s)= 107 to L(sub s) = 109. We examined a total of 409 images from L(sub s) = 107 to L(sub s)=148. We have also examined data from 2000 from L(sub s)= 93 to L(sub s)= 110; additional progress is ongoing. Here we present a progress report of our observations, and continue to determine their implications for the Martian water cycle.

  6. Anatomic brain asymmetry in vervet monkeys.

    PubMed

    Fears, Scott C; Scheibel, Kevin; Abaryan, Zvart; Lee, Chris; Service, Susan K; Jorgensen, Matthew J; Fairbanks, Lynn A; Cantor, Rita M; Freimer, Nelson B; Woods, Roger P

    2011-01-01

    Asymmetry is a prominent feature of human brains with important functional consequences. Many asymmetric traits show population bias, but little is known about the genetic and environmental sources contributing to inter-individual variance. Anatomic asymmetry has been observed in Old World monkeys, but the evidence for the direction and extent of asymmetry is equivocal and only one study has estimated the genetic contributions to inter-individual variance. In this study we characterize a range of qualitative and quantitative asymmetry measures in structural brain MRIs acquired from an extended pedigree of Old World vervet monkeys (n = 357), and implement variance component methods to estimate the proportion of trait variance attributable to genetic and environmental sources. Four of six asymmetry measures show pedigree-level bias and one of the traits has a significant heritability estimate of about 30%. We also found that environmental variables more significantly influence the width of the right compared to the left prefrontal lobe.

  7. Diurnal variability of the planetary albedo: An appraisal with satellite measurements and general circulation models

    SciTech Connect

    Potter, G.L.; Cess, R.D.; Minnis, P.; Harrison, E.F.; Ramanathan, V.

    1988-03-01

    This study addresses two aspects of the planetary albedo's diurnal cycle, the first of which refers to directional models of the planetary albedo. It is found that even for clear regions there appear to be deficiencies in our knowledge of how to model this quantity. Over land surfaces, for example, Nimbus-7 data for the directional planetary albedo compare best with model calculations for which a Lambertian surface is assumed, despite ample evidence that the albedo of land surfaces is dependent upon solar zenith angle. Similarly, over ocean surfaces both GOES and Nimbus-7 data produce a weaker dependence of the planetary albedo upon solar zenith angle than would be suggested by model calculations.

  8. Lemon albedo as a new source of dietary fiber: Application to bologna sausages.

    PubMed

    Fernández-Ginés, J M; Fernández-López, J; Sayas-Barberá, E; Sendra, E; Pérez-Álvarez, J A

    2004-05-01

    The aim of this work was to study the effect of the addition of lemon albedo in bologna sausages. Two types of albedo (raw and cooked) and five concentrations (0%, 2.5%, 5%, 7.5% and 10%) were added to sausages. Chemical, physicochemical and sensory analyses were made. The addition of albedo to bologna sausages represents an improvement in their nutritional properties and may have beneficial effects, possibly due to the presence of active biocompounds which induce a decrease in residual nitrite levels. The formulations which gave products with sensory properties similar to conventional sausages were sausages with 2.5% and 5% raw albedo and 2.5%, 5% and 7.5% cooked albedo.

  9. Carbon-equivalent metrics for albedo changes in land management contexts: relevance of the time dimension.

    PubMed

    Bright, Ryan M; Bogren, Wiley; Bernier, Pierre; Astrup, Rasmus

    2016-09-01

    Surface albedo is an important physical property by which the land surface regulates climate. A wide and growing body of literature suggests that failing to account for surface albedo can result in suboptimal or even counterproductive climate-motivated policies of the land-based sectors. As such, albedo changes are increasingly included in climate impact assessments of forestry and other land sector projects through conversion of radiative forcings into carbon or carbon dioxide equivalents. However, the prevailing methodology does not sufficiently accommodate dynamic albedo changes on land or CO2 in the atmosphere. We present two new metrics designed to address these deficiencies, referring to them as the time-dependent emissions equivalent and the time-independent emissions equivalent of albedo changes. We demonstrate their application in various land management contexts and discuss their merits and uncertainties.

  10. ARM Climate Research Facility Spectral Surface Albedo Value-Added Product (VAP) Report

    SciTech Connect

    McFarlane, S; Gaustad, K; Long, C; Mlawer, E

    2011-07-15

    This document describes the input requirements, output data products, and methodology for the Spectral Surface Albedo (SURFSPECALB) value-added product (VAP). The SURFSPECALB VAP produces a best-estimate near-continuous high spectral resolution albedo data product using measurements from multifilter radiometers (MFRs). The VAP first identifies best estimates for the MFR downwelling and upwelling shortwave irradiance values, and then calculates narrowband spectral albedo from these best-estimate irradiance values. The methodology for finding the best-estimate values is based on a simple process of screening suspect data and backfilling screened and missing data with estimated values when possible. The resulting best-estimate MFR narrowband spectral albedos are used to determine a daily surface type (snow, 100% vegetation, partial vegetation, or 0% vegetation). For non-snow surfaces, a piecewise continuous function is used to estimate a high spectral resolution albedo at 1 min temporal and 10 cm-1 spectral resolution.

  11. Shape and Albedo from Shading (SAfS) for Pixel-Level dem Generation from Monocular Images Constrained by Low-Resolution dem

    NASA Astrophysics Data System (ADS)

    Wu, Bo; Chung Liu, Wai; Grumpe, Arne; Wöhler, Christian

    2016-06-01

    Lunar topographic information, e.g., lunar DEM (Digital Elevation Model), is very important for lunar exploration missions and scientific research. Lunar DEMs are typically generated from photogrammetric image processing or laser altimetry, of which photogrammetric methods require multiple stereo images of an area. DEMs generated from these methods are usually achieved by various interpolation techniques, leading to interpolation artifacts in the resulting DEM. On the other hand, photometric shape reconstruction, e.g., SfS (Shape from Shading), extensively studied in the field of Computer Vision has been introduced to pixel-level resolution DEM refinement. SfS methods have the ability to reconstruct pixel-wise terrain details that explain a given image of the terrain. If the terrain and its corresponding pixel-wise albedo were to be estimated simultaneously, this is a SAfS (Shape and Albedo from Shading) problem and it will be under-determined without additional information. Previous works show strong statistical regularities in albedo of natural objects, and this is even more logically valid in the case of lunar surface due to its lower surface albedo complexity than the Earth. In this paper we suggest a method that refines a lower-resolution DEM to pixel-level resolution given a monocular image of the coverage with known light source, at the same time we also estimate the corresponding pixel-wise albedo map. We regulate the behaviour of albedo and shape such that the optimized terrain and albedo are the likely solutions that explain the corresponding image. The parameters in the approach are optimized through a kernel-based relaxation framework to gain computational advantages. In this research we experimentally employ the Lunar-Lambertian model for reflectance modelling; the framework of the algorithm is expected to be independent of a specific reflectance model. Experiments are carried out using the monocular images from Lunar Reconnaissance Orbiter (LRO

  12. Aerosol Single-Scattering Albedo Derived from MODIS Reflectances over a Bright Surface

    NASA Astrophysics Data System (ADS)

    Wells, K. C.; Martins, J.; Remer, L. A.; Kreidenweis, S. M.; Stephens, G. L.

    2010-12-01

    The sign and magnitude of the aerosol radiative forcing over bright surfaces is highly dependent on the absorbing properties of the aerosol. Thus, the determination of aerosol forcing over desert regions requires accurate information about the aerosol single-scattering albedo (SSA). However, the brightness of desert surfaces complicates the retrieval of aerosol optical properties using passive space-based measurements. The aerosol critical reflectance is one parameter that can be used to relate TOA reflectance changes over land to the aerosol absorption properties, without knowledge of the underlying surface properties or aerosol loading. Physically, the parameter represents the TOA reflectance at which increased aerosol scattering due to increased aerosol loading is balanced by increased absorption of the surface contribution to the TOA reflectance. It can be derived by comparing two satellite images with different aerosol loading, assuming that the surface reflectance and background aerosol is similar between the two days. In this work, we explore the utility of the critical reflectance method for routine monitoring of spectral aerosol absorption from space over North Africa, a region that is predominantly impacted by absorbing dust and biomass burning aerosol. We derive the critical reflectance from MODIS Level 1B reflectances in the vicinity of two AERONET stations: Tamanrasset, a site in the Algerian Sahara, and Banizoumbou, a Sahelian site in Niger. We examine the sensitivity of the critical reflectance parameter to aerosol physical and optical properties, as well as solar and viewing geometry, using the SBDART model, and apply our findings to retrieve SSA from the MODIS critical reflectance values. We compare our results to AERONET-retrieved estimates, as well as measurements of the TOA albedo and surface fluxes from GERB, ARM, and CERES data. Spectral SSA values retrieved at Banizoumbou result in TOA forcing estimates that agree with CERES measurements

  13. Surface albedo darkening from wildfires in northern sub-Saharan Africa

    NASA Astrophysics Data System (ADS)

    Gatebe, C. K.; Ichoku, C. M.; Poudyal, R.; Román, M. O.; Wilcox, E.

    2014-05-01

    Northern sub-Saharan Africa (NSSA) has a wide variety of climate zones or biomes, where albedo dynamics are highly coupled with vegetation dynamics and fire disturbances. Quantifying surface albedo variations due to fire disturbances on time scales of several months to several years is complex and is made worse by lack of accurate and spatially consistent surface albedo data. Here, we estimate the surface albedo effect from wildfires in different land cover types in the NSSA region using Moderate Resolution Imaging Spectroradiometer (MODIS) multi-year observational data (2003-11). The average decrease in albedo after fires at the scale of 1 km MODIS footprint is -0.002 02 ± 0.000 03 for woody savanna and -0.002 22 ± 0.000 03 for savanna. These two land cover types together account for >86% of the total MODIS fire count between 2003 and 2011. We found that only a small fraction of the pixels (≦̸10%) burn in two successive years and about 47% had any fire recurrence in 9 years. The study also derived the trajectories of post-fire albedo dynamics from the percentages of pixels that recover to pre-fire albedo values each year. We found that the persistence of surface albedo darkening in most land cover types in the NSSA region is limited to about 6-7 years, after which at least 99% of the burnt pixels recover to their pre-fire albedo. Our results provide critical information for deriving necessary input to various models used in determining the effects of albedo change due to wild fires in the NSSA region.

  14. DIRECTIONAL DEPENDENCE OF {Lambda}CDM COSMOLOGICAL PARAMETERS

    SciTech Connect

    Axelsson, M.; Fantaye, Y.; Hansen, F. K.; Eriksen, H. K.; Banday, A. J.; Gorski, K. M. E-mail: y.t.fantaye@astro.uio.no

    2013-08-10

    We study hemispherical power asymmetry in the Wilkinson Microwave Anisotropy Probe 9 yr data. We analyze the combined V- and W-band sky maps, after application of the KQ85 mask, and find that the asymmetry is statistically significant at the 3.4{sigma} confidence level for l = 2-600, where the data are signal-dominated, with a preferred asymmetry direction (l, b) = (227, -27). Individual asymmetry axes estimated from six independent multipole ranges are all consistent with this direction. Subsequently, we estimate cosmological parameters on different parts of the sky and show that the parameters A{sub s} , n{sub s} , and {Omega}{sub b} are the most sensitive to this power asymmetry. In particular, for the two opposite hemispheres aligned with the preferred asymmetry axis, we find n{sub s} = 0.959 {+-} 0.022 and n{sub s} = 0.989 {+-} 0.024, respectively.

  15. Asymmetry effects in fragment production

    NASA Astrophysics Data System (ADS)

    Kaur, Manpreet; Kaur, Varinderjit

    2016-05-01

    The production of different fragments has been studied by taking into account the mass asymmetry of the reaction and employing the momentum dependent interactions. Two different set of asymmetric reactions have been analyzed while keeping Atotal fixed using soft momentum dependent equation of state. Our results indicate that the impact of momentum dependent interactions is different in lighter projectile systems as compared to heavier ones. The comparative analysis of IQMD simulations with the experimental data in case of heavier projectile and lighter target system for the reaction of 197Au+27Al (η = 0.7) at E = 600 MeV/nucleon shows that with the inclusion of MDI we are able, upto some extent, to reproduce the experimental universality of rise and fall of intermediate mass fragments (IMFs).

  16. Collins Asymmetry at Hadron Colliders

    SciTech Connect

    Yuan, Feng

    2008-01-17

    We study the Collins effect in the azimuthal asymmetricdistribution of hadrons inside a high energy jet in the single transversepolarized proton proton scattering. From the detailed analysis ofone-gluon and two-gluon exchange diagrams contributions, the Collinsfunction is found the same as that in the semi-inclusive deep inelasticscattering and e+e- annihilations. The eikonal propagators in thesediagrams do not contribute to the phase needed for the Collins-typesingle spin asymmetry, and the universality is derived as a result of theWard identity. We argue that this conclusion depends on the momentum flowof the exchanged gluon and the kinematic constraints in the fragmentationprocess, and is generic and model-independent.

  17. Integral Quantification of Soil Water Content at the Intermediate Catchment Scale by Ground Albedo Neutron Sensing (GANS)

    NASA Astrophysics Data System (ADS)

    Rivera Villarreyes, C. A.; Baroni, G.; Oswald, S. E.

    2012-04-01

    Soil water content at the plot or hill-slope scale is an important link between local vadose zone hydrology and catchment hydrology. However, so far only few methods are on the way to close this gap between point measurements and remote sensing. One new measurement methodology for integral quantifications of mean areal soil water content at the intermediate catchment scale is the aboveground sensing of cosmic-ray neutrons, more precisely ground albedo neutron sensing (GANS). Ground albedo natural neutrons, are generated by collisions of secondary cosmic rays with land surface materials (soil, water, biomass, snow, etc). Neutrons measured at the air/ground interface correlate with soil moisture contained in a footprint of ca. 600 m diameter and a depth ranging down to a few decimeters. This correlation is based on the crucial role of hydrogen as neutron moderator compared to others landscape materials. The present study performed ground albedo neutron sensing in different locations in Germany under different vegetative situations (cropped and bare field) and different seasonal conditions (summer, autumn and winter). Ground albedo neutrons were measured at (i) a farmland close to Potsdam (Brandenburg, Germany) cropped with corn in 2010 and sunflowers in 2011, and (ii) a mountainous farmland catchment (Schaefertal, Harz Mountains, Germany) in 2011. In order to test this method, classical soil moisture devices and meteorological data were used for comparison. Moreover, calibration approach, and transferability of calibration parameters to different times and locations are also evaluated. Our observations suggest that GANS can overcome the lack of data for hydrological processes at the intermediate scale. Soil water content from GANS compared quantitatively with mean water content values derived from a network of classical devices (RMSE = 0.02 m3/m3 and r2 = 0.98) in three calibration periods with cropped-field conditions. Then, same calibration parameters corresponded

  18. The Dependence of the Ice-Albedo Feedback on Atmospheric Properties

    PubMed Central

    Selsis, F.; Kitzmann, D.; Rauer, H.

    2013-01-01

    Abstract Ice-albedo feedback is a potentially important destabilizing effect for the climate of terrestrial planets. It is based on the positive feedback between decreasing surface temperatures, an increase of snow and ice cover, and an associated increase in planetary albedo, which then further decreases surface temperature. A recent study shows that for M stars, the strength of the ice-albedo feedback is reduced due to the strong spectral dependence of stellar radiation and snow/ice albedos; that is, M stars primarily emit in the near IR, where the snow and ice albedo is low, and less in the visible, where the snow/ice albedo is high. This study investigates the influence of the atmosphere (in terms of surface pressure and atmospheric composition) on this feedback, since an atmosphere was neglected in previous studies. A plane-parallel radiative transfer model was used for the calculation of planetary albedos. We varied CO2 partial pressures as well as the H2O, CH4, and O3 content in the atmosphere for planets orbiting Sun-like and M type stars. Results suggest that, for planets around M stars, the ice-albedo effect is significantly reduced, compared to planets around Sun-like stars. Including the effects of an atmosphere further suppresses the sensitivity to the ice-albedo effect. Atmospheric key properties such as surface pressure, but also the abundance of radiative trace gases, can considerably change the strength of the ice-albedo feedback. For dense CO2 atmospheres of the order of a few to tens of bar, atmospheric rather than surface properties begin to dominate the planetary radiation budget. At high CO2 pressures, the ice-albedo feedback is strongly reduced for planets around M stars. The presence of trace amounts of H2O and CH4 in the atmosphere also weakens the ice-albedo effect for both stellar types considered. For planets around Sun-like stars, O3 could also lead to a very strong decrease of the ice-albedo feedback at high CO2 pressures. Key Words

  19. Satellite derived albedoes during spring melt for selected locations in the Arctic

    NASA Astrophysics Data System (ADS)

    Busse, J.; Anderson, M.

    2005-12-01

    Snow and ice surfaces have a high level of reflectance, therefore, a high albedo, compared to open water and soil which have lower albedo values and absorb more sunlight. As the high albedo snow and ice begins to melt, the albedo values drop. This contributes to a positive feedback mechanism. The dropping albedo values indicate that more radiation is being absorbed by the surface. As more radiation is absorbed by the surface, more melt occurs, which then leads to lower albedoes and more absorption. This positive feedback continues until the fall when new snow covers the surface and the albedo begins to increase, disrupting the cycle. In the Arctic, the amount of sea ice surviving the summer melt season continues to decrease, indicating a change in the surface conditions during this important melt season. However, very little is known about the albedoes during the melt period. This study documents the albedo changes that occur during the melt season and compares these changes to melt onset dates derived from passive microwave data in order to obtain a multi-frequency response to the energy conditions. Time series of albedo data from the AVHRR Polar Pathfinder Twice-Daily 25-km EASE-Grid Composites are obtained to show the transition from winter to summer conditions from 13 different points within the Arctic. Areas experiencing melt are explored and melt onset dates are determined. Snow and ice melt can also be detected using SMMR and SSM/I passive microwave data. Microwave data are useful to pinpoint when melt occurs, because microwaves can also detect changes in surface conditions. The albedo data are compared with melt onset dates obtained from microwave sensors to determine relationships between microwave-derived melt and albedo responses. Data from areas experiencing early melt onset and late melt onset are explored. Studying the time series from the 13 different points in the Arctic show the relationship between surface melt and albedo variations during the

  20. The dependence of the ice-albedo feedback on atmospheric properties.

    PubMed

    von Paris, P; Selsis, F; Kitzmann, D; Rauer, H

    2013-10-01

    Ice-albedo feedback is a potentially important destabilizing effect for the climate of terrestrial planets. It is based on the positive feedback between decreasing surface temperatures, an increase of snow and ice cover, and an associated increase in planetary albedo, which then further decreases surface temperature. A recent study shows that for M stars, the strength of the ice-albedo feedback is reduced due to the strong spectral dependence of stellar radiation and snow/ice albedos; that is, M stars primarily emit in the near IR, where the snow and ice albedo is low, and less in the visible, where the snow/ice albedo is high. This study investigates the influence of the atmosphere (in terms of surface pressure and atmospheric composition) on this feedback, since an atmosphere was neglected in previous studies. A plane-parallel radiative transfer model was used for the calculation of planetary albedos. We varied CO₂ partial pressures as well as the H₂O, CH₄, and O₃ content in the atmosphere for planets orbiting Sun-like and M type stars. Results suggest that, for planets around M stars, the ice-albedo effect is significantly reduced, compared to planets around Sun-like stars. Including the effects of an atmosphere further suppresses the sensitivity to the ice-albedo effect. Atmospheric key properties such as surface pressure, but also the abundance of radiative trace gases, can considerably change the strength of the ice-albedo feedback. For dense CO₂ atmospheres of the order of a few to tens of bar, atmospheric rather than surface properties begin to dominate the planetary radiation budget. At high CO₂ pressures, the ice-albedo feedback is strongly reduced for planets around M stars. The presence of trace amounts of H₂O and CH₄ in the atmosphere also weakens the ice-albedo effect for both stellar types considered. For planets around Sun-like stars, O₃ could also lead to a very strong decrease of the ice-albedo feedback at high CO₂ pressures.

  1. Palatal asymmetry during development: an anatomical study.

    PubMed

    Moreira, R S; Sgrott, E A; Stuker, H; Alonso, L G; Smith, R L

    2008-07-01

    The purpose of this study was to evaluate hard palate asymmetry during development. The palates of 248 dry skulls were photographed and evaluated digitally. The skulls were divided into seven groups: fetus, newborn, infant, child, adolescent, adult, and aged. Linear measures were obtained from great palatine foramen (GPF) to incisive fossa (INC) and to posterior nasal spine (PNS). Angular measures were obtained from the former landmarks plus the point on sutures intersection between maxillary and palatine bones. Asymmetry was evaluated intra and intergroups. All skulls showed some degree of right-left asymmetry in the hard palate. Regardless of hard palate asymmetry, none of the right-left side differences was statistically significant. For the intergroups assessment, none of the asymmetry index means were statistically different. The posterior part of palate (PNS x GPF) measures was more asymmetric than the anterior part (INC x GPF), showing, respectively, 4.6% and 2.8% of mean asymmetry index. Angular measures showed a more symmetric behavior than the linear ones. Hard palate asymmetry occurs even in the absence of masticatory function, showing that this feature begins early in fetal life and persists through development.

  2. Abnormal asymmetry of brain connectivity in schizophrenia.

    PubMed

    Ribolsi, Michele; Daskalakis, Zafiris J; Siracusano, Alberto; Koch, Giacomo

    2014-01-01

    Recently, a growing body of data has revealed that beyond a dysfunction of connectivity among different brain areas in schizophrenia patients (SCZ), there is also an abnormal asymmetry of functional connectivity compared with healthy subjects. The loss of the cerebral torque and the abnormalities of gyrification, with an increased or more complex cortical folding in the right hemisphere may provide an anatomical basis for such aberrant connectivity in SCZ. Furthermore, diffusion tensor imaging studies have shown a significant reduction of leftward asymmetry in some key white-matter tracts in SCZ. In this paper, we review the studies that investigated both structural brain asymmetry and asymmetry of functional connectivity in healthy subjects and SCZ. From an analysis of the existing literature on this topic, we can hypothesize an overall generally attenuated asymmetry of functional connectivity in SCZ compared to healthy controls. Such attenuated asymmetry increases with the duration of the disease and correlates with psychotic symptoms. Finally, we hypothesize that structural deficits across the corpus callosum may contribute to the abnormal asymmetry of intra-hemispheric connectivity in schizophrenia.

  3. Development of a high spectral resolution surface albedo product for the ARM Southern Great Plains Central Facility

    SciTech Connect

    McFarlane, Sally A.; Gaustad, Krista L.; Mlawer, Eli J.; Long, Charles N.; Delamere, Jennifer

    2011-09-01

    We present a method for identifying dominant surface type and estimating high spectral resolution surface albedo at the Atmospheric Radiation Measurement (ARM) facility at the Southern Great Plains (SGP) site in Oklahoma for use in radiative transfer calculations. Given a set of 6-channel narrowband visible and near-infrared irradiance measurements from upward and downward looking multi-filter radiometers (MFRs), four different surface types (snow-covered, green vegetation, partial vegetation, non-vegetated) can be identified. A normalized difference vegetation index (NDVI) is used to distinguish between vegetated and non-vegetated surfaces, and a scaled NDVI index is used to estimate the percentage of green vegetation in partially vegetated surfaces. Based on libraries of spectral albedo measurements, a piecewise continuous function is developed to estimate the high spectral resolution surface albedo for each surface type given the MFR albedo values as input. For partially vegetated surfaces, the albedo is estimated as a linear combination of the green vegetation and non-vegetated surface albedo values. The estimated albedo values are evaluated through comparison to high spectral resolution albedo measurements taken during several Intensive Observational Periods (IOPs) and through comparison of the integrated spectral albedo values to observed broadband albedo measurements. The estimated spectral albedo values agree well with observations for the visible wavelengths constrained by the MFR measurements, but have larger biases and variability at longer wavelengths. Additional MFR channels at 1100 nm and/or 1600 nm would help constrain the high resolution spectral albedo in the near infrared region.

  4. Asymmetry in Time Evolution of Magnetization in Magnetic Nanostructures

    DOE PAGES

    Tóbik, Jaroslav; Cambel, Vladimir; Karapetrov, Goran

    2015-07-22

    Strong interest in nanomagnetism stems from the promise of high storage densities of information through control of ever smaller and smaller ensembles of spins. There is a broad consensus that the Landau-Lifshitz-Gilbert equation reliably describes the magnetization dynamics on classical phenomenological level. On the other hand, it is not so evident that the magnetization dynamics governed by this equation contains built-in asymmetry in the case of broad topology sets of symmetric total energy functional surfaces. The magnetization dynamics in such cases shows preference for one particular state from many energetically equivalent available minima. Here, we demonstrate this behavior on amore » simple one-spin model which can be treated analytically. Depending on the ferromagnet geometry and material parameters, this asymmetric behavior can be robust enough to survive even at high temperatures opening simplified venues for controlling magnetic states of nanodevices in practical applications. Using micromagnetic simulations we demonstrate the asymmetry in magnetization dynamics in a real system with reduced symmetry such as Pacman-like nanodot. Finally, exploiting the built-in asymmetry in the dynamics could lead to practical methods of preparing desired spin configurations on nanoscale. Introduction« less

  5. Asymmetry in Time Evolution of Magnetization in Magnetic Nanostructures

    SciTech Connect

    Tóbik, Jaroslav; Cambel, Vladimir; Karapetrov, Goran

    2015-07-22

    Strong interest in nanomagnetism stems from the promise of high storage densities of information through control of ever smaller and smaller ensembles of spins. There is a broad consensus that the Landau-Lifshitz-Gilbert equation reliably describes the magnetization dynamics on classical phenomenological level. On the other hand, it is not so evident that the magnetization dynamics governed by this equation contains built-in asymmetry in the case of broad topology sets of symmetric total energy functional surfaces. The magnetization dynamics in such cases shows preference for one particular state from many energetically equivalent available minima. Here, we demonstrate this behavior on a simple one-spin model which can be treated analytically. Depending on the ferromagnet geometry and material parameters, this asymmetric behavior can be robust enough to survive even at high temperatures opening simplified venues for controlling magnetic states of nanodevices in practical applications. Using micromagnetic simulations we demonstrate the asymmetry in magnetization dynamics in a real system with reduced symmetry such as Pacman-like nanodot. Finally, exploiting the built-in asymmetry in the dynamics could lead to practical methods of preparing desired spin configurations on nanoscale. Introduction

  6. Asymmetry in Time Evolution of Magnetization in Magnetic Nanostructures

    PubMed Central

    Tóbik, Jaroslav; Cambel, Vladimir; Karapetrov, Goran

    2015-01-01

    Strong interest in nanomagnetism stems from the promise of high storage densities of information through control of ever smaller and smaller ensembles of spins. There is a broad consensus that the Landau-Lifshitz-Gilbert equation reliably describes the magnetization dynamics on classical phenomenological level. On the other hand, it is not so evident that the magnetization dynamics governed by this equation contains built-in asymmetry in the case of broad topology sets of symmetric total energy functional surfaces. The magnetization dynamics in such cases shows preference for one particular state from many energetically equivalent available minima. We demonstrate this behavior on a simple one-spin model which can be treated analytically. Depending on the ferromagnet geometry and material parameters, this asymmetric behavior can be robust enough to survive even at high temperatures opening simplified venues for controlling magnetic states of nanodevices in practical applications. Using micromagnetic simulations we demonstrate the asymmetry in magnetization dynamics in a real system with reduced symmetry such as Pacman-like nanodot. Exploiting the built-in asymmetry in the dynamics could lead to practical methods of preparing desired spin configurations on nanoscale. PMID:26198544

  7. The annual asymmetry in the F2 layer during deep solar minimum (2008-2009): December anomaly

    NASA Astrophysics Data System (ADS)

    Mikhailov, A. V.; Perrone, L.

    2015-02-01

    Annual January/July midlatitude daytime asymmetry in monthly median NmF2 and model thermospheric parameters has been considered during deep solar minimum, (2008-2009), when solar and geomagnetic activities were at the lowest level, to analyze the background effect due to the Sun-Earth minimum distance, perihelion, in the vicinity of the December solstice. Averaged over 10 midlatitude station pairs, the NmF2 asymmetry was found to be ≈1.23, while the average asymmetry for the annual component in NmF2 variations is ≈1.17. Annual asymmetry in monthly median neutral composition and temperature predicted by Mass Spectrometer Incoherent Scatter 86 (MSIS86) and MSISE00 thermospheric models along with the 7% increase in solar EUV flux in the vicinity of the December solstice is sufficient to explain the observed annual asymmetry in NmF2. A hierarchy of aeronomic parameters responsible for the observed asymmetry in NmF2 has been established: the main contributor is atomic oxygen—about 50% of the total effect, [N2] contributes around 35% strongly compensating the [O] contribution, and solar EUV and Tn provide <10% each. The zonal mean annual asymmetry in MSIS86 atomic oxygen column density was shown to be 1.18 at low and middle latitudes, and this is close to the estimated asymmetry for the annual component in NmF2 variations. The earlier proposed mechanism of the December anomaly is considered as a plausible one to explain the 1.18 January/July asymmetry in the atomic oxygen variations and consequently the NmF2 annual daytime asymmetry at middle latitudes under the deep solar minimum.

  8. Using Remote Sensing to Quantify Roof Albedo in Seven California Cities

    NASA Astrophysics Data System (ADS)

    Ban-Weiss, G. A.; Woods, J.; Millstein, D.; Levinson, R.

    2013-12-01

    Cool roofs reflect sunlight and therefore can reduce cooling energy use in buildings. Further, since roofs cover about 20-25% of cities, wide spread deployment of cool roofs could mitigate the urban heat island effect and partially counter urban temperature increases associated with global climate change. Accurately predicting the potential for increasing urban albedo using reflective roofs and its associated energy use and climate benefits requires detailed knowledge of the current stock of roofs at the city scale. Until now this knowledge has been limited due to a lack of availability of albedo data with sufficient spatial coverage, spatial resolution, and spectral information. In this work we use a novel source of multiband aerial imagery to derive the albedos of individual roofs in seven California cities: Los Angeles, Long Beach, San Diego, Bakersfield, Sacramento, San Francisco, and San Jose. The radiometrically calibrated, remotely sensed imagery has high spatial resolution (1 m) and four narrow (less than 0.1 μm wide) band reflectances: blue, green, red, and near-infrared. To derive the albedo of roofs in each city, we first locate roof pixels within GIS building outlines. Next we use laboratory measurements of the solar spectral reflectances of 190 roofing products to empirically relate solar reflectance (albedo) to reflectances in the four narrow bands; the root-mean-square of the residuals for the albedo prediction is 0.016. Albedos computed from remotely sensed reflectances are calibrated to ground measurements of roof albedo in each city. The error (both precision and accuracy) of albedo values is presented for each city. The area-weighted mean roof albedo (× standard deviation) for each city ranges from 0.17 × 0.08 (Los Angeles) to 0.29 × 0.15 (San Diego). In each city most roofs have low albedo in the range of 0.1 to 0.3. Roofs with albedo greater than 0.4 comprise less than 3% of total roofs and 7% of total roof area in each city. The California

  9. Climate implications of including albedo effects in terrestrial carbon policy

    NASA Astrophysics Data System (ADS)

    Jones, A. D.; Collins, W.; Torn, M. S.; Calvin, K. V.

    2012-12-01

    Proposed strategies for managing terrestrial carbon in order to mitigate anthropogenic climate change, such as financial incentives for afforestation, soil carbon sequestration, or biofuel production, largely ignore the direct effects of land use change on climate via biophysical processes that alter surface energy and water budgets. Subsequent influences on temperature, hydrology, and atmospheric circulation at regional and global scales could potentially help or hinder climate stabilization efforts. Because these policies often rely on payments or credits expressed in units of CO2-equivalents, accounting for biophysical effects would require a metric for comparing the strength of biophysical climate perturbation from land use change to that of emitting CO2. One such candidate metric that has been suggested in the literature on land use impacts is radiative forcing, which underlies the global warming potential metric used to compare the climate effects of various greenhouse gases with one another. Expressing land use change in units of radiative forcing is possible because albedo change results in a net top-of-atmosphere radiative flux change. However, this approach has also been critiqued on theoretical grounds because not all climatic changes associated with land use change are principally radiative in nature, e.g. changes in hydrology or the vertical distribution of heat within the atmosphere, and because the spatial scale of land use change forcing differs from that of well-mixed greenhouse gases. To explore the potential magnitude of this discrepancy in the context of plausible scenarios of future land use change, we conduct three simulations with the Community Climate System Model 4 (CCSM4) utilizing a slab ocean model. Each simulation examines the effect of a stepwise change in forcing relative to a pre-industrial control simulation: 1) widespread conversion of forest land to crops resulting in approximately 1 W/m2 global-mean radiative forcing from albedo

  10. Albedo Properties of Small (0.5 to 20 km) Main Belt Asteroids

    NASA Astrophysics Data System (ADS)

    Ryan, Erin L.; Woodward, C. E.

    2010-01-01

    Serendipitous observations of main belt asteroids by the Spitzer Space Telescope have enabled determination of main belt asteroid albedos and diameters for targets as small as 0.5 km (eg., Ryan et al. 2009, AJ, 137, 5134). We have used multi-epoch data at 5.8, 8.0 and 24 microns from the MIPSGAL and Taurus Legacy Surveys to obtain diameters and albedos for a sample of approximately 2000 main belt asteroids. Using STM and NEATM, we have obtained diameters ranging from 0.5 to 30 km and albedos ranging from 0.02 to 0.5. Results of this program reveal an albedo distribution that is more diverse in range than the albedo distribution seen in the IRAS and MSX surveys. This diversity may reflect effects of space weathering reddening which is selectively reddening larger asteroids. This reddening effect may reinforce the findings from accretion models that indicate that asteroids in the early solar system were 100 km and larger (Morbidelli et al., 2009, Icarus, in press), by suggesting that the larger asteroids are indeed the oldest members of the main belt. We will present results on the albedo distribution as a function of semi-major axis and new analysis of the mean albedo of dynamical families within the main belt. Support for this work provided in part by a National Science Foundation grant AST-0706980 to the University of Minnesota.

  11. Near-ground cooling efficacies of trees and high-albedo surfaces

    SciTech Connect

    Levinson, Ronnen M.

    1997-05-01

    Daytime summer urban heat islands arise when the prevalence of dark-colored surfaces and lack of vegetation make a city warmer than neighboring countryside. Two frequently-proposed summer heat island mitigation measures are to plant trees and to increase the albedo (solar reflectivity) of ground surfaces. This dissertation examines the effects of these measures on the surface temperature of an object near the ground, and on solar heating of air near the ground. Near-ground objects include people, vehicles, and buildings. The variation of the surface temperature of a near-ground object with ground albedo indicates that a rise in ground albedo will cool a near-ground object only if the object`s albedo exceeds a critical value. This critical value of object albedo depends on wind speed, object geometry, and the height of the atmospheric thermal boundary layer. It ranges from 0.15 to 0.37 for a person. If an object has typical albedo of 0.3, increasing the ground albedo by.

  12. A global assessment of forest surface albedo and its relationships with climate and atmospheric nitrogen deposition.

    PubMed

    Leonardi, Stefano; Magnani, Federico; Nolè, Angelo; Van Noije, Twan; Borghetti, Marco

    2015-01-01

    We present a global assessment of the relationships between the short-wave surface albedo of forests, derived from the MODIS satellite instrument product at 0.5° spatial resolution, with simulated atmospheric nitrogen deposition rates (Ndep ), and climatic variables (mean annual temperature Tm and total annual precipitation P), compiled at the same spatial resolution. The analysis was performed on the following five forest plant functional types (PFTs): evergreen needle-leaf forests (ENF); evergreen broad-leaf forests (EBF); deciduous needle-leaf forests (DNF); deciduous broad-leaf forests (DBF); and mixed-forests (MF). Generalized additive models (GAMs) were applied in the exploratory analysis to assess the functional nature of short-wave surface albedo relations to environmental variables. The analysis showed evident correlations of albedo with environmental predictors when data were pooled across PFTs: Tm and Ndep displayed a positive relationship with forest albedo, while a negative relationship was detected with P. These correlations are primarily due to surface albedo differences between conifer and broad-leaf species, and different species geographical distributions. However, the analysis performed within individual PFTs, strengthened by attempts to select 'pure' pixels in terms of species composition, showed significant correlations with annual precipitation and nitrogen deposition, pointing toward the potential effect of environmental variables on forest surface albedo at the ecosystem level. Overall, our global assessment emphasizes the importance of elucidating the ecological mechanisms that link environmental conditions and forest canopy properties for an improved parameterization of surface albedo in climate models.

  13. Estimation of solar backscatter ultraviolet albedo using ground-based Umkehr measurements

    SciTech Connect

    DeLuisi, J.J. ); Longenecker, D.U. ); Chu, W.P. ); Mateer, C.L.

    1993-02-20

    A retrieval method was developed to estimate the solar backscatter ultraviolet (SBUV) satellite albedo for the ozone profiler wavelengths using ground-based ultraviolet measurements. For the present investigation the Umkehr was used as the ground-based ultraviolet measurement. Simulated SBUV data and Umkehr data theoretically computed from a priori ozone profiles observed by the SAGE II satellite were used to develop the retrieval algorithm and to test its capability. The test indicated that albedos for the SBUV ozone profiler wavelengths should allow estimates to a precision of [plus minus]5% or better, depending on the accuracy of the ultraviolet measurement. Retrievals using actual Umkehr observations were also performed to provide a preliminary look at the magnitude and annual variation of retrieved albedos. A case study was performed, comparing retrieved albedos with SBUV-measured albedos. The SBUV albedo change was seen to be approximately twice as large as the albedo changes estimated by the Umkehr method. Results of the investigation suggest that the method of estimation may be useful for determining the drift rate of the SBUV calibration. 20 refs., 5 figs., 4 tabs.

  14. Analysis of earth albedo effect on sun sensor measurements based on theoretical model and mission experience

    NASA Technical Reports Server (NTRS)

    Brasoveanu, Dan; Sedlak, Joseph

    1998-01-01

    Analysis of flight data from previous missions indicates that anomalous Sun sensor readings could be caused by Earth albedo interference. A previous Sun sensor study presented a detailed mathematical model of this effect. The model can be used to study the effect of both diffusive and specular reflections and to improve Sun angle determination based on perturbed Sun sensor measurements, satellite position, and an approximate knowledge of attitude. The model predicts that diffuse reflected light can cause errors of up to 10 degrees in Coarse Sun Sensor (CSS) measurements and 5 to 10 arc sec in Fine Sun Sensor (FSS) measurements, depending on spacecraft orbit and attitude. The accuracy of these sensors is affected as long as part of the illuminated Earth surface is present in the sensor field of view. Digital Sun Sensors (DSS) respond in a different manner to the Earth albedo interference. Most of the time DSS measurements are not affected, but for brief periods of time the Earth albedo can cause errors which are a multiple of the sensor least significant bit and may exceed one degree. This paper compares model predictions with Tropical Rainfall Measuring Mission (TRMM) CSS measurements in order to validate and refine the model. Methods of reducing and mitigating the impact of Earth albedo are discussed. ne CSS sensor errors are roughly proportional to the Earth albedo coefficient. Photocells that are sensitive only to ultraviolet emissions would reduce the effective Earth albedo by up to a thousand times, virtually eliminating all errors caused by Earth albedo interference.

  15. Variation in foliar nitrogen and albedo in response to nitrogen fertilization and elevated CO2.

    PubMed

    Wicklein, Haley F; Ollinger, Scott V; Martin, Mary E; Hollinger, David Y; Lepine, Lucie C; Day, Michelle C; Bartlett, Megan K; Richardson, Andrew D; Norby, Richard J

    2012-08-01

    Foliar nitrogen has been shown to be positively correlated with midsummer canopy albedo and canopy near infrared (NIR) reflectance over a broad range of plant functional types (e.g., forests, grasslands, and agricultural lands). To date, the mechanism(s) driving the nitrogen–albedo relationship have not been established, and it is unknown whether factors affecting nitrogen availability will also influence albedo. To address these questions, we examined variation in foliar nitrogen in relation to leaf spectral properties, leaf mass per unit area, and leaf water content for three deciduous species subjected to either nitrogen (Harvard Forest, MA, and Oak Ridge, TN) or CO(2) fertilization (Oak Ridge, TN). At Oak Ridge, we also obtained canopy reflectance data from the airborne visible/infrared imaging spectrometer (AVIRIS) to examine whether canopy-level spectral responses were consistent with leaf-level results. At the leaf level, results showed no differences in reflectance or transmittance between CO(2) or nitrogen treatments, despite significant changes in foliar nitrogen. Contrary to our expectations, there was a significant, but negative, relationship between foliar nitrogen and leaf albedo, a relationship that held for both full spectrum leaf albedo as well as leaf albedo in the NIR region alone. In contrast, remote sensing data indicated an increase in canopy NIR reflectance with nitrogen fertilization. Collectively, these results suggest that altered nitrogen availability can affect canopy albedo, albeit by mechanisms that involve canopy-level processes rather than changes in leaf-level reflectance.

  16. Evaluation of Moderate-Resolution Imaging Spectroradiometer (MODIS) Snow Albedo Product (MCD43A) over Tundra

    NASA Technical Reports Server (NTRS)

    Wang, Zhuosen; Schaaf, Crystal B.; Chopping, Mark J.; Strahler, Alan H.; Wang, Jindi; Roman, Miguel O.; Rocha, Adrian V.; Woodcock, Curtis E.; Shuai, Yanmin

    2012-01-01

    This study assesses the MODIS standard Bidirectional Reflectance Distribution Function (BRDF)/Albedo product, and the daily Direct Broadcast BRDF/Albedo algorithm at tundra locations under large solar zenith angles and high anisotropic diffuse illumination and multiple scattering conditions. These products generally agree with ground-based albedo measurements during the snow cover period when the Solar Zenith Angle (SZA) is less than 70deg. An integrated validation strategy, including analysis of the representativeness of the surface heterogeneity, is performed to decide whether direct comparisons between field measurements and 500- m satellite products were appropriate or if the scaling of finer spatial resolution airborne or spaceborne data was necessary. Results indicate that the Root Mean Square Errors (RMSEs) are less than 0.047 during the snow covered periods for all MCD43 albedo products at several Alaskan tundra areas. The MCD43 1- day daily albedo product is particularly well suited to capture the rapidly changing surface conditions during the spring snow melt. Results also show that a full expression of the blue sky albedo is necessary at these large SZA snow covered areas because of the effects of anisotropic diffuse illumination and multiple scattering. In tundra locations with dark residue as a result of fire, the MODIS albedo values are lower than those at the unburned site from the start of snowmelt.

  17. Estimation of Instantaneous TOA Albedo at 670 nm over Ice Clouds from POLDER Multidirectional Measurements

    NASA Technical Reports Server (NTRS)

    Sun, W.; Loeb, N. G.; Kato, S.

    2003-01-01

    An algorithm that determines the 670-nm top-of-atmosphere (TOA) albedo of ice clouds over ocean using Polarization and Directionality of the Earth's Reflectance ( POLDER) multidirectional measurements is developed. A plane-parallel layer of ice cloud with various optical thicknesses and light scattering phase functions is assumed. For simplicity, we use a double Henyey-Greenstein phase function to approximate the volume-averaged phase function of the ice clouds. A multidirectional reflectance best-fit match between theoretical and POLDER reflectances is used to infer effective cloud optical thickness, phase function and TOA albedo. Sensitivity tests show that while the method does not provide accurate independent retrievals of effective cloud optical depth and phase function, TOA albedo retrievals are accurate to within similar to 3% for both a single layer of ice clouds or a multilayer system of ice clouds and water clouds. When the method is applied to POLDER measurements and retrieved albedos are compared with albedos based on empirical angular distribution models (ADMs), zonal albedo differences are generally smaller than similar to 3%. When albedos are compared with those on the POLDER-I ERB and Cloud product, the differences can reach similar to 15% at small solar zenith angles.

  18. Relic Density of Neutrinos with Primordial Asymmetries

    SciTech Connect

    Pastor, Sergio; Pinto, Teguayco; Raffelt, Georg G.

    2009-06-19

    We study flavor oscillations in the early Universe, assuming primordial neutrino-antineutrino asymmetries. Including collisions and pair processes in the kinetic equations, we not only estimate the degree of flavor equilibration, but for the first time also kinetic equilibration among neutrinos and with the ambient plasma. Typically, the restrictive big-bang nucleosynthesis bound on the nu{sub e}nu{sub e} asymmetry indeed applies to all flavors as claimed in the previous literature, but fine-tuned initial asymmetries always allow for a large surviving neutrino excess radiation that may show up in precision cosmological data.

  19. Relic density of neutrinos with primordial asymmetries.

    PubMed

    Pastor, Sergio; Pinto, Teguayco; Raffelt, Georg G

    2009-06-19

    We study flavor oscillations in the early Universe, assuming primordial neutrino-antineutrino asymmetries. Including collisions and pair processes in the kinetic equations, we not only estimate the degree of flavor equilibration, but for the first time also kinetic equilibration among neutrinos and with the ambient plasma. Typically, the restrictive big-bang nucleosynthesis bound on the nu_{e}nu[over]_{e} asymmetry indeed applies to all flavors as claimed in the previous literature, but fine-tuned initial asymmetries always allow for a large surviving neutrino excess radiation that may show up in precision cosmological data.

  20. Management of Asymmetry After Breast Reduction.

    PubMed

    Garcia, Onelio

    2016-04-01

    Breast reduction surgery has achieved one of the highest patient satisfaction rates among plastic surgery procedures. Most of the complications encountered are usually minor and related to wound healing. Revision surgery to address these problems is common and usually consists of scar revisions. Postoperative breast asymmetry of a mild degree is also common; however, postoperative asymmetry severe enough to warrant surgical revision is a rare event, occurring in less than 1% of cases. Postmammaplasty revision surgery needs to be individualized. The asymmetry could be the result of nipple malposition or it could consist of a volume or shape discrepancy between the breast mounds.

  1. Migration of Frosts from High-Albedo Regions of Pluto: what New Horizons Reveals

    NASA Astrophysics Data System (ADS)

    Buratti, Bonnie J.; Stern, S. A.; Weaver, Hal A.; Young, Leslie A.; Olkin, Cathy B.; Ennico, Kimberly; Binzel, Richard P.; Zangari, Amanda; Earle, Alissa M.

    2015-11-01

    With its high eccentricity and obliquity, Pluto should exhibit seasonal volatile transport on its surface. Several lines of evidence support this transport: doubling of Pluto’s atmospheric pressure over the past two decades (Young et al., 2013, Ap. J. 766, L22; Olkin et al., 2015, Icarus 246, 230); changes in its historical rotational light curve, once all variations due to viewing geometry have been modelled (Buratti et al., 2015; Ap. J. 804, L6); and changes in HST albedo maps (Buie et al., 2010, Astron. J. 139, 1128). New Horizons LORRI images reveal that the region of greatest albedo change is not the polar cap(s) of Pluto, but the feature informally named Tombaugh Regio (TR). This feature has a normal reflectance as high as ~0.8 in some places, and it is superposed on older, lower-albedo pre-existing terrain with an albedo of only ~0.10. This contrast is larger than any other body in the Solar System, except for Iapetus. This albedo dichotomy leads to a complicated system of cold-trapping and thermal segregation, beyond the simple picture of seasonal volatile transport. Whatever the origin of TR, it initially acted as a cold trap, as the temperature differential between the high and low albedo regions could be enormous, possibly approaching 20K, based on their albedo differences and assuming their normalized phase curves are similar. This latter assumption will be refined as the full New Horizons data set is returned.Over six decades of ground-based photometry suggest that TR has been decreasing in albedo over the last 25 years. Possible causes include changing insolation angles, or sublimation from the edges where the high-albedo material impinges on a much warmer substrate.Funding by the NASA New Horizons Project acknowledged.

  2. On Spectral Invariance of Single Scattering Albedo for Weakly Absorbing Wavelengths

    NASA Technical Reports Server (NTRS)

    Marshak, Alexander

    2012-01-01

    The single scattering albedo omega (sub 0 lambda) in atmospheric radiative transfer is the ratio of the scattering coefficient to the total extinction coefficient. For cloud water droplets both the scattering and absorption coefficients, thus the single scattering albedo, are functions of wavelength A and droplet size r. In this presentation we will show that for water droplets at weakly absorbing wavelengths, the ratio omega (sub 0 lambda)(r). The slope and intercept of the linear function are wavelength independent and sum to unity. This relationship allows for a representation of any single scattering albedo omega (sub 0 lambda) via one known spectrum omega (sub 0 lambda)(r(sub o)). We will provide a simple physical explanation of the discovered relationship. In addition to water droplets, similar linear relationships were found for the single scattering albedo of non-spherical ice crystals. The single scattering albedo $\\omega _ {0\\lambda }$ in atmospheric radiative transfer is the ratio of the scattering coefficient to the total extinction coefficient. For cloud water droplets both the scattering and absorption coefficients, and thus the single scattering albedo, are functions of wavelength $\\lambda $ and droplet size $r$. We show that for water droplets at weakly absorbing wavelengths, the ratio $\\omega _ {0\\lambda } (r)$/$\\omega _ {0\\lambda } (r_{0})$ of two single scattering albedo spectra for two different droplet sizes is a linear function of $\\omega _{0\\lambda }(r)$. The slope and intercept of the linear function are wavelength independent and sum to unity. This relationship allows for a representation of any single scattering albedo $\\omega_{0\\lambda }(r)$ via one known spectrum $\\omega_{0\\lambda }(r_{0})$. We provide a simple physical explanation of the discovered relationship. Similar linear relationships characterize the single scattering albedo of non-spherical ice crystals.

  3. Quantifying the missing link between albedo and productivity of boreal forests

    NASA Astrophysics Data System (ADS)

    Hovi, Aarne; Liang, Jingjing; Korhonen, Lauri; Kobayashi, Hideki; Rautiainen, Miina

    2016-04-01

    Albedo and fraction of absorbed photosynthetically active radiation (FAPAR) determine the shortwave radiation balance and productivity of forests. Several studies have examined the relation between forest structure and albedo in the boreal zone. Studies regarding FAPAR are fewer and the relations between albedo and FAPAR are still poorly understood. To study these relations we simulated shortwave black sky albedo and canopy FAPAR, using the FRT forest reflectance model. We used two sets of field plots as input data. The plots were located in Alaska, USA (N = 584) and in Finland (N = 506) between Northern latitudes of 60° and 68° , and they represent naturally grown and more intensively managed (regularly thinned) forests, respectively. The simulations were carried out with sun zenith angles (SZA) typical to the biome, ranging from 40° to 80° . The simulated albedos in coniferous plots decreased with increasing tree height, whereas canopy FAPAR showed an opposite trend. The albedo of broadleaved plots was notably higher than that of coniferous plots. No species differences in canopy FAPAR were seen, except for pine forests in Finland that showed lowest FAPAR among species. Albedo and canopy FAPAR were negatively correlated (r ranged from -0.93 to -0.69) in coniferous plots. The correlations were notably weaker (r ranged from -0.64 to 0.05) if plots with broadleaved trees were included. To show the influence of forest management, we further examined the response of albedo and FAPAR to forest density (basal area) and fraction of broadleaved trees. Plots with low basal area showed high albedos but also low canopy FAPAR. When comparing the sparse plots to dense ones, the relative decrease in canopy FAPAR was larger than the relative increase in albedo. However, at large SZAs the basal area could be lowered to approx. 20 m2 ha-1 before FAPAR was notably reduced. Increasing the proportion of broadleaved trees from 0% to 100% increased the albedos to approximately

  4. Measurement of the absolute hohlraum wall albedo under ignition foot drive conditions

    SciTech Connect

    Suter, L J; Wallace, R J; Hammel, B A; Weber, F A; Landen, O L; Campbell, K M; DeWald, E L; Glenzer, S H; Rosen, M D; Jones, O S; Turner, R E; Kauffmann, R L; Hammer, J H

    2003-11-25

    We present the first measurements of the absolute albedos of hohlraums made from gold or from high-Z mixtures. The measurements are performed over the range of radiation temperatures (70-100 eV) expected during the foot of an indirect-drive temporally-shaped ignition laser pulse, where accurate knowledge of the wall albedo (i.e. soft x-ray wall re-emission) is most critical for determining capsule radiation symmetry. We find that the gold albedo agrees well with calculations using the super transition array opacity model, potentially providing additional margin for ICF ignition.

  5. Albedo protons and electrons at ISS - an important contribution to astronaut dose?

    NASA Astrophysics Data System (ADS)

    Norman, R. B.; Slaba, T. C.; Badavi, F. F.; Mertens, C. J.; Blattnig, S.

    2015-12-01

    Albedo particles, which are created by cosmic ray interactions in the atmosphere and are moving upwards away from the surface of the earth, are often considered a negligible contribution to astronaut radiation exposure on the International Space Station (ISS). Models of astronaut exposure, however, consistently underestimate measurements onboard ISS when these albedo particles are neglected. Recent measurements by instruments on ISS (AMS, PAMELA, and SEDA-AP) hint that there are high energy protons and electrons which are not being modeled and that may contribute to radiation exposure on ISS. Estimates of the contribution of radiation exposure on ISS due to albedo particles, along with open questions, will be discussed.

  6. A note on solar elevation dependence of clear sky snow albedo

    NASA Technical Reports Server (NTRS)

    Choudhury, B. J.

    1981-01-01

    Recent attempts to match shortwave albedo of snow for clear skies using approximate spectral solar fluxes and solutions of the radiative transfer equation for snow were unsuccessful until a separate surface reflection term was introduced. A separate consideration of specular reflection from surface snow grains has been objected to as being ad hoc. Results based on a new parameterization of shortwave radiation are discussed. Compared to the previous radiation models, new model gives higher diffuse insolation and predicts higher albedos. The difference between observed and predicted albedos is substantially reduced without invoking surface reflection.

  7. Near-Infrared Albedos of Main Belt Asteroids and Families from NEOWISE

    NASA Astrophysics Data System (ADS)

    Masiero, Joseph R.; Grav, T.; Mainzer, A. K.; Nugent, C. R.; Bauer, J. M.; Stevenson, R.; Sonnett, S.

    2014-11-01

    We present new results from revised thermal models of Main Belt asteroids in the NEOWISE dataset, focusing on the 3.4- and 4.6-micron albedos of asteroids and asteroid families. We show that the Main Belt is well described by three unique 3.4-micron albedo groups, tracing to the C-complex, S-complex, and K-type asteroids. Among large asteroid families, the Eos family shows a reflectance behavior that is unique in the Main Belt, matching the K-type albedo group. This work is described in detail in a recently published article in the Astrophysical Journal.

  8. Experimental Characterization Of The Asymmetry And The Dip Form Of The H{sub {beta}}-Line Profiles In Microwave-Produced Plasmas At Atmospheric Pressure

    SciTech Connect

    Palomares, J. M.; Torres, J.; Gamero, A.; Sola, A.; Gigosos, M. A.; Mullen, J. J. A. M. van der

    2008-10-22

    An experimental study on the asymmetry of the Balmer H{sub {beta}} profile in plasmas produced by microwaves at atmospheric pressure is presented. The asymmetry of the whole profile is studied with the help of one function that quantified this characteristic. The asymmetry and shape of the central valley is also studied with the definition of several parameters. The study shows the presence of the Stark asymmetry in plasmas with electron density of the order of 10{sup 21}m{sup -3}.

  9. Symmetry and asymmetry in the human brain

    NASA Astrophysics Data System (ADS)

    Hugdahl, Kenneth

    2005-10-01

    Structural and functional asymmetry in the human brain and nervous system is reviewed in a historical perspective, focusing on the pioneering work of Broca, Wernicke, Sperry, and Geschwind. Structural and functional asymmetry is exemplified from work done in our laboratory on auditory laterality using an empirical procedure called dichotic listening. This also involves different ways of validating the dichotic listening procedure against both invasive and non-invasive techniques, including PET and fMRI blood flow recordings. A major argument is that the human brain shows a substantial interaction between structurally, or "bottom-up" asymmetry and cognitively, or "top-down" modulation, through a focus of attention to the right or left side in auditory space. These results open up a more dynamic and interactive view of functional brain asymmetry than the traditional static view that the brain is lateralized, or asymmetric, only for specific stimuli and stimulus properties.

  10. Optimal Branching Asymmetry of Hydrodynamic Pulsatile Trees

    NASA Astrophysics Data System (ADS)

    Florens, Magali; Sapoval, Bernard; Filoche, Marcel

    2011-04-01

    Most of the studies on optimal transport are done for steady state regime conditions. Yet, there exists numerous examples in living systems where supply tree networks have to deliver products in a limited time due to the pulsatile character of the flow, as it is the case for mammalian respiration. We report here that introducing a systematic branching asymmetry allows the tree to reduce the average delivery time of the products. It simultaneously increases its robustness against the inevitable variability of sizes related to morphogenesis. We then apply this approach to the human tracheobronchial tree. We show that in this case all extremities are supplied with fresh air, provided that the asymmetry is smaller than a critical threshold which happens to match the asymmetry measured in the human lung. This could indicate that the structure is tuned at the maximum asymmetry level that allows the lung to feed all terminal units with fresh air.

  11. Brain asymmetry: both sides of the story.

    PubMed

    Samara, Athina; Tsangaris, George T

    2011-12-01

    Biological systems demonstrate asymmetry, while lateralization has been observed from humans to lower animals structurally, functionally and behaviorally. This may be derived from evolutionary, genetic, developmental, epigenetic and pathologic factors. However, brain structure and function is complex, and macroscopic or microscopic asymmetries are hard to discern from random fluctuations. In this article, we discuss brain laterality and lateralization, beginning with a brief review of the literature on brain structural and functional asymmetries. We conclude with methods to detect and quantify asymmetry, focusing on neuroproteomics, for retrieval of protein-expression patterns, as a method of diagnosis and treatment monitoring. We suggest inter-hemispheric differential proteomics as a valid method to assess the experimental and biological variations in the healthy brain, and neurologic and neuropsychiatric disorders.

  12. A Cloud Hydrology and Albedo Synthesis Mission (CHASM)

    NASA Technical Reports Server (NTRS)

    Davies, Roger

    2004-01-01

    This slide presentation reviews the Cloud Hydrology and Albedo Synthesis Mission (CHASM). The interaction of clouds with radiation and the hydrological cycle represents a huge uncertainty in our understanding of climate science and the modeling of climate system feedbacks. Despite the recognized need for a unified treatment of cloud processes, the present global average values of remotely sensed cloud liquid water and theoretically accepted values used for cloud physics and precipitation modeling differ by an order of magnitude. This is due in part to sampling and saturation effects, as well as to threedimensional cloud structure effects. In recent work with the Multiangle Imaging SpectroRadiometer (MISR) on Terra, we have gained new insights as to how the remote sensing approach could be significantly improved using a new instrument that combines passive optical (visible and near infrared) and microwave measurements, both as pushbroom scanners with multiple viewing angles, to the degree that measurements of liquid water path over deep convective clouds over land also become possible. This instrument would also have the ability of measuring height-resolved cloud-tracked winds using a hyper stereo retrieval technique. Deployment into a precessing low earth orbit would be optimal for measuring diurnal cloud activity. We have explored an instrument design concept for this that looks promising if we can establish partnerships that provide launch and bus capabilities.

  13. Compositional Variation in Large-Diameter Low-Albedo asteroids

    NASA Astrophysics Data System (ADS)

    Vilas, F.; Jarvis, K. S.; Thibault, C. A.; Sawyer, S. R.

    2000-12-01

    Age dating of meteorites indicates that the Solar System was subjected to a major heating event 4.5 Gyr ago. Models of the effects of heating by electromagnetic induction or decay of short-lived radionuclides combined with models of the early collisional history of the Solar System after Jupiter's formation indicate that asteroids observed today can be divided into two groups by diameter. Those asteroids having diameters greater than 100 km were mixed by multiple collisions but remain as gravitationally bound rubble piles. Asteroids with diameters less than 100 km should show more compositional diversity. Vilas and Sykes (1996, Icarus, 124) have shown using ECAS photometry that this compositional difference exists. The larger diameter group should be individually homogenous, with spectral differences showing the combined effects of a primordial compositional gradient in the asteroid belt with thermal metamorphism. We address the significance of 36 rotationally-resolved spectra of larger-diameter low-albedo asteroids of the C class (and subclasses B, F, G) and P class in the visible and Near-IR spectral regions. This work was supported by the NASA Planetary Astronomy program.

  14. Dual radio frequency plasma source: Understanding via electrical asymmetry effect

    SciTech Connect

    Bora, B.; Bhuyan, H.; Favre, M.; Wyndham, E.; Wong, C. S.

    2013-04-21

    On the basis of the global model, the influences of driving voltage and frequency on electron heating in geometrically symmetrical dual capacitively coupled radio frequency plasma have been investigated. Consistent with the experimental and simulation results, non-monotonic behavior of dc self bias and plasma heating with increasing high frequency is observed. In addition to the local maxima of plasma parameters for the integer values of the ratio between the frequencies ({xi}), ourstudies also predict local maxima for odd integer values of 2{xi} as a consequence of the electrical asymmetry effect produced by dual frequency voltage sources.

  15. Bottom production asymmetries at the LHC

    SciTech Connect

    Norrbin, E.; Vogt, R.

    1999-01-01

    We present results on bottom hadron production asymmetries at the LHC within both the Lund string fragmentation model and the intrinsic bottom model. The main aspects of the models are summarized and specific predictions for pp collisions at 14 TeV are given. Asymmetries are found to be very small at central rapidities increasing to a few percent at forward rapidities. At very large rapidities intrinsic production could dominate but this region is probably out of reach of any experiment.

  16. Baryon asymmetry, inflation and squeezed states

    SciTech Connect

    Bambah, Bindu A. . E-mail: bbsp@uohyd.ernet.in; Chaitanya, K.V.S. Shiv; Mukku, C.

    2007-04-15

    We use the general formalism of squeezed rotated states to calculate baryon asymmetry in the wake of inflation through parametric amplification. We base our analysis on a B and CP violating Lagrangian in an isotropically expanding universe. The B and CP violating terms originate from the coupling of complex fields with non-zero baryon number to a complex background inflaton field. We show that a differential amplification of particle and antiparticle modes gives rise to baryon asymmetry.

  17. Forward-backward asymmetries of atomic photoelectrons.

    SciTech Connect

    Biheux, J. C.; Dunford, R. W.; Gemmell, D. S.; Hasegawa, S.; Kanter, E. P.; Krassig, B.; Southworth, S. H.; Young, L.

    1999-01-19

    When atomic photoionization is treated beyond the dipole approximation, photoelectron angular distributions are asymmetric forward and backward with respect to the direction of the photon beam. We have measured forward-backward asymmetries of Ar 1s and Kr 1s and 2s photoelectrons using 2-19 keV x-rays. The measured asymmetries compare well with calculations which include interference between electric-dipole and electric-quadrupole amplitudes within the nonrelativistic, independent-particle approximations.

  18. CP asymmetries with longitudinal and transverse beam polarizations in neutralino production and decay into the Z0 boson at the ILC

    NASA Astrophysics Data System (ADS)

    Bartl, Alfred; Hohenwarter-Sodek, Karl; Kernreiter, Thomas; Kittel, Olaf

    2007-09-01

    We study neutralino production at the linear collider with the subsequent two-body decays tilde chi0i → tilde chi0nZ0 and Z0 → ell bar-ell, with ell = e, μ, τ, or Z0 → qbar q with q = c, b. We show that transverse electron and positron beam polarizations allow the definition of unique CP observables. These are azimuthal asymmetries in the distributions of the final leptons or quarks. We calculate these CP asymmetries and the cross sections in the Minimal Supersymmetric Standard Model with complex higgsino and gaugino parameters μ and M1. For final quark pairs, we find CP asymmetries as large as 30%. We discuss the significances for observing the CP asymmetries at the International Linear Collider (ILC). Finally we compare the CP asymmetries with those asymmetries which require unpolarized and/or longitudinally polarized beams only.

  19. Poloidal asymmetries in edge transport barriersa)

    NASA Astrophysics Data System (ADS)

    Churchill, R. M.; Theiler, C.; Lipschultz, B.; Hutchinson, I. H.; Reinke, M. L.; Whyte, D.; Hughes, J. W.; Catto, P.; Landreman, M.; Ernst, D.; Chang, C. S.; Hager, R.; Hubbard, A.; Ennever, P.; Walk, J. R.

    2015-05-01

    Measurements of impurities in Alcator C-Mod indicate that in the pedestal region, significant poloidal asymmetries can exist in the impurity density, ion temperature, and main ion density. In light of the observation that ion temperature and electrostatic potential are not constant on a flux surface [Theiler et al., Nucl. Fusion 54, 083017 (2014)], a technique based on total pressure conservation to align profiles measured at separate poloidal locations is presented and applied. Gyrokinetic neoclassical simulations with XGCa support the observed large poloidal variations in ion temperature and density, and that the total pressure is approximately constant on a flux surface. With the updated alignment technique, the observed in-out asymmetry in impurity density is reduced from previous publishing [Churchill et al., Nucl. Fusion 53, 122002 (2013)], but remains substantial ( n z , H / n z , L ˜ 6 ). Candidate asymmetry drivers are explored, showing that neither non-uniform impurity sources nor localized fluctuation-driven transport are able to explain satisfactorily the impurity density asymmetry. Since impurity density asymmetries are only present in plasmas with strong electron density gradients, and radial transport timescales become comparable to parallel transport timescales in the pedestal region, it is suggested that global transport effects relating to the strong electron density gradients in the pedestal are the main driver for the pedestal in-out impurity density asymmetry.

  20. Asymmetries observed in Saturn's magnetopause geometry.

    PubMed

    Pilkington, N M; Achilleos, N; Arridge, C S; Guio, P; Masters, A; Ray, L C; Sergis, N; Thomsen, M F; Coates, A J; Dougherty, M K

    2015-09-16

    For over 10 years, the Cassini spacecraft has patrolled Saturn's magnetosphere and observed its magnetopause boundary over a wide range of prevailing solar wind and interior plasma conditions. We now have data that enable us to resolve a significant dawn-dusk asymmetry and find that the magnetosphere extends farther from the planet on the dawnside of the planet by 7 ± 1%. In addition, an opposing dawn-dusk asymmetry in the suprathermal plasma pressure adjacent to the magnetopause has been observed. This probably acts to reduce the size asymmetry and may explain the discrepancy between the degree of asymmetry found here and a similar asymmetry found by Kivelson and Jia (2014) using MHD simulations. Finally, these observations sample a wide range of season, allowing the "intrinsic" polar flattening (14 ± 1%) caused by the magnetodisc to be separated from the seasonally induced north-south asymmetry in the magnetopause shape found theoretically (5 ± 1% when the planet's magnetic dipole is tilted away from the Sun by 10-17°).

  1. Asymmetries observed in Saturn's magnetopause geometry

    NASA Astrophysics Data System (ADS)

    Pilkington, N. M.; Achilleos, N.; Arridge, C. S.; Guio, P.; Masters, A.; Ray, L. C.; Sergis, N.; Thomsen, M. F.; Coates, A. J.; Dougherty, M. K.

    2015-09-01

    For over 10 years, the Cassini spacecraft has patrolled Saturn's magnetosphere and observed its magnetopause boundary over a wide range of prevailing solar wind and interior plasma conditions. We now have data that enable us to resolve a significant dawn-dusk asymmetry and find that the magnetosphere extends farther from the planet on the dawnside of the planet by 7 ± 1%. In addition, an opposing dawn-dusk asymmetry in the suprathermal plasma pressure adjacent to the magnetopause has been observed. This probably acts to reduce the size asymmetry and may explain the discrepancy between the degree of asymmetry found here and a similar asymmetry found by Kivelson and Jia (2014) using MHD simulations. Finally, these observations sample a wide range of season, allowing the "intrinsic" polar flattening (14 ± 1%) caused by the magnetodisc to be separated from the seasonally induced north-south asymmetry in the magnetopause shape found theoretically (5 ± 1% when the planet's magnetic dipole is tilted away from the Sun by 10-17°).

  2. A robust quantification of galaxy cluster morphology using asymmetry and central concentration

    SciTech Connect

    Nurgaliev, D.; Stubbs, C. W.; McDonald, M.; Miller, E. D.; Benson, B. A.; Vikhlinin, A.

    2013-12-20

    We present a novel quantitative scheme of cluster classification based on the morphological properties that are manifested in X-ray images. We use a conventional radial surface brightness concentration parameter (c {sub SB}) as defined previously by others and a new asymmetry parameter, which we define in this paper. Our asymmetry parameter, which we refer to as photon asymmetry (A {sub phot}), was developed as a robust substructure statistic for cluster observations with only a few thousand counts. To demonstrate that photon asymmetry exhibits better stability than currently popular power ratios and centroid shifts, we artificially degrade the X-ray image quality by (1) adding extra background counts, (2) eliminating a fraction of the counts, (3) increasing the width of the smoothing kernel, and (4) simulating cluster observations at higher redshift. The asymmetry statistic presented here has a smaller statistical uncertainty than competing substructure parameters, allowing for low levels of substructure to be measured with confidence. A {sub phot} is less sensitive to the total number of counts than competing substructure statistics, making it an ideal candidate for quantifying substructure in samples of distant clusters covering a wide range of observational signal-to-noise ratios. Additionally, we show that the asymmetry-concentration classification separates relaxed, cool-core clusters from morphologically disturbed mergers, in agreement with by-eye classifications. Our algorithms, freely available as Python scripts (https://github.com/ndaniyar/aphot), are completely automatic and can be used to rapidly classify galaxy cluster morphology for large numbers of clusters without human intervention.

  3. An evaluation of high-resolution regional climate model simulations of snow cover and albedo over the Rocky Mountains, with implications for the simulated snow-albedo feedback

    NASA Astrophysics Data System (ADS)

    Minder, Justin R.; Letcher, Theodore W.; Skiles, S. McKenzie

    2016-08-01

    The snow-albedo feedback (SAF) strongly influences climate over midlatitude mountainous regions. However, over these regions the skill of regional climate models (RCMs) at simulating properties such as snow cover and surface albedo is poorly characterized. These properties are evaluated in a pair of 7 year long high-resolution RCM simulations with the Weather Research and Forecasting model over the central Rocky Mountains. Key differences between the simulations include the computational domain (regional versus continental) and land surface model used (Noah versus Noah-MP). Simulations are evaluated against high-resolution satellite estimates of snow cover and albedo from the Moderate Resolution Imaging Spectroradiometer. Both simulations generally reproduce the observed seasonal and spatial variability of snow cover and also exhibit important biases. One simulation substantially overpredicts subpixel fractional snow cover over snowy pixels (by up to 0.4) causing large positive biases in surface albedo, likely due in part to inadequate representation of canopy effects. The other simulation exhibits a negative bias in areal snow extent (as much as 19% of the analysis domain). Surface measurements reveal large positive biases in snow albedo (exceeding 0.2) during late spring caused by neglecting radiative effects of impurities deposited onto snow. Semi-idealized climate change experiments show substantially different magnitudes of SAF-enhanced warming in the two simulations that can be tied to the differences in snow cover in their control climates. More confident projections of regional climate change over mountains will require further work to evaluate and improve representation of snow cover and albedo in RCMs.

  4. Analysis of dark albedo features on a southern polar dune field of Mars.

    PubMed

    Horváth, András; Kereszturi, Akos; Bérczi, Szaniszló; Sik, András; Pócs, Tamás; Gánti, Tibor; Szathmáry, Eörs

    2009-01-01

    We observed 20-200 m sized low-albedo seepage-like streaks and their annual change on defrosting polar dunes in the southern hemisphere of Mars, based on the Mars Orbiter Camera (MOC), High Resolution Stereo Camera (HRSC), and High Resolution Imaging Science Experiment (HiRISE) images. The structures originate from dark spots and can be described as elongated or flowlike and, at places, branching streaks. They frequently have another spotlike structure at their end. Their overall appearance and the correlation between their morphometric parameters suggest that some material is transported downward from the spots and accumulates at the bottom of the dune's slopes. Here, we present possible scenarios for the origin of such streaks, including dry avalanche, liquid CO(2), liquid H(2)O, and gas-phase CO(2). Based on their morphology and the currently known surface conditions of Mars, no model interprets the streaks satisfactorily. The best interpretation of only the morphology and morphometric characteristics is only given by the model that implies some liquid water. The latest HiRISE images are also promising and suggest liquid flow. We suggest, with better knowledge of sub-ice temperatures that result from extended polar solar insolation and the heat insulator capacity of water vapor and water ice, future models and measurements may show that ephemeral water could appear and flow under the surface ice layer on the dunes today.

  5. Solar Wind Interaction with Lunar Crustal Magnetic Fields: Relation to Albedo Swirls

    NASA Technical Reports Server (NTRS)

    Mitchell, D. L.; Lin, R. P.; Harrison, L.; Halekas, J. S.; Hood, L. L.; Acuna, M. H.; Binder, A. B.

    2000-01-01

    The Magnetometer/Electron Reflectometer onboard Lunar Prospector has observed the solar wind interaction with remanent crustal magnetic fields at altitudes from 20 to 120 km. This interaction may be responsible for the formation of albedo swirls.

  6. Regional Mapping of the Lunar Crustal Magnetic Field: Correlation of Strong Anomalies with Curvilinear Albedo Markings

    NASA Technical Reports Server (NTRS)

    Hood, L. L.; Yingst, A.; Zakharian, A.; Lin, R. P.; Mitchell, D. L.; Halekas, J.; Acuna, M. H.; Binder, A. B.

    2000-01-01

    Using high-resolution regional Lunar Prospector magnetometer magnetic field maps, we report here a close correlation of the strongest individual crustal anomalies with unusual curvilinear albedo markings of the Reiner Gamma class.

  7. The albedo, effective temperature, and energy balance of Uranus, as determined from Voyager IRIS data

    SciTech Connect

    Pearl, J.C.; Conrath, B.J.; Hanel, R.A.; Pirraglia, J.A.; Coustenis, A. Paris, Observatoire, Meudon )

    1990-03-01

    The albedo, T(eff), and energy balance of Uranus are presently derived from Voyager IR Spectrometer and Radiometer data. By obtaining the absolute phase curve of Uranus, it has become possible to evaluate the Bond albedo without making separate determinations of the geometric albedo and phase integral. An orbital mean value for the bolometric Bond albedo of 0.3 + or - 0.049 yields an equilibrium temperature of 58.2 + or - 1.0 K. Thermal spectra from pole-to-pole latitude coverage establish a T(eff) of 59.1 + or - 0.3 K, leading to an energy balance of 1.06 + or - 0.08 for Uranus. 39 refs.

  8. Plasmon-resonant gold nanorods as low backscattering albedo contrast agents for optical coherence tomography.

    PubMed

    Oldenburg, Amy L; Hansen, Matthew N; Zweifel, Daniel A; Wei, Alexander; Boppart, Stephen A

    2006-07-24

    Plasmon-resonant gold nanorods are demonstrated as low backscattering albedo contrast agents for optical coherence tomography (OCT). We define the backscattering albedo, a', as the ratio of the backscattering to extinction coefficient. Contrast agents which modify a' within the host tissue phantoms are detected with greater sensitivity by the differential OCT measurement of both a' and extinction. Optimum sensitivity is achieved by maximizing the difference between contrast agents and tissue, |a'(ca) - a'(tiss)|. Low backscattering albedo gold nanorods (14x 44 nm; lambda(max) = 780 nm) within a high backscattering albedo tissue phantom with an uncertainty in concentration of 20% (randomized 2+/-0.4% intralipid) were readily detected at 82 ppm (by weight) in a regime where extinction alone could not discriminate nanorods. The estimated threshold of detection was 30 ppm.

  9. Operational comparison of TLD albedo dosemeters and solid state nuclear tracks detectors in fuel fabrication facilities.

    PubMed

    Tsujimura, N; Takada, C; Yoshida, T; Momose, T

    2007-01-01

    The authors carried out an operational study that compared the use of TLD albedo dosemeters and solid state nuclear tracks detector in plutonium environments of Japan Nuclear Cycle Development Institute, Tokai Works. A selected group of workers engaged in the fabrication process of MOX (Plutonium-Uranium mixed oxide) fuel wore both TLD albedo dosemeters and solid state nuclear tracks detectors. The TL readings were generally proportional to the counted etch-pits, and thus the dose equivalent results obtained from TLD albedo dosemeter agreed with those from solid state nuclear tracks detector within a factor of 1.5. This result indicates that, in the workplaces of the MOX fuel plants, the neutron spectrum remained almost constant in terms of time and space, and the appropriate range of field-specific correction with spectrum variations was small in albedo dosimetry.

  10. Energy and Angular Spectra of Albedo Protons and Neutrons Emitted from Hydrated Layers of Lunar Regolith

    NASA Astrophysics Data System (ADS)

    Townsend, L. W.; Zaman, F.; Schwadron, N. A.; Wilson, J. K.; Spence, H. E.; Case, A. W.; Kasper, J. C.; Mazur, J. E.; Looper, M. D.

    2016-11-01

    Energy and angular yields of albedo protons and neutrons emitted from the lunar surface as a function of hydration layer thickness in the lunar regolith using the MCNP computer code developed at Los Alamos National Laboratory are presented.

  11. The albedo, effective temperature, and energy balance of Uranus, as determined from Voyager IRIS data

    NASA Technical Reports Server (NTRS)

    Pearl, J. C.; Conrath, B. J.; Hanel, R. A.; Pirraglia, J. A.; Coustenis, A.

    1990-01-01

    The albedo, T(eff), and energy balance of Uranus are presently derived from Voyager IR Spectrometer and Radiometer data. By obtaining the absolute phase curve of Uranus, it has become possible to evaluate the Bond albedo without making separate determinations of the geometric albedo and phase integral. An orbital mean value for the bolometric Bond albedo of 0.3 + or - 0.049 yields an equilibrium temperature of 58.2 + or - 1.0 K. Thermal spectra from pole-to-pole latitude coverage establish a T(eff) of 59.1 + or - 0.3 K, leading to an energy balance of 1.06 + or - 0.08 for Uranus.

  12. The surface abundance and stratigraphy of lunar rocks from data about their albedo

    NASA Technical Reports Server (NTRS)

    Shevchenko, V. V.

    1977-01-01

    The data pf ground-based studies and surveys of the lunar surface by the Zond and Apollo spacecraft have been used to construct an albedo map covering 80 percent of the lunar sphere. Statistical analysis of the distribution of areas with various albedos shows several types of lunar surface. Comparison of albedo data for maria and continental areas with the results of geochemical orbital surveys allows the identification of the types of surface with known types of lunar rock. The aluminum/silcon and magnesium/silicon ratios as measured by the geochemical experiments on the Apollo 15 and Apollo 16 spacecraft were used as an indication of the chemical composition of the rock. The relationship of the relative aluminum content to the age of crystalline rocks allows a direct dependence to be constructed between the mean albedo of areas and the age of the rocks of which they are composed.

  13. The extreme ultraviolet albedos of the planet Mercury and of the moon

    NASA Technical Reports Server (NTRS)

    Wu, H. H.; Broadfoot, A. L.

    1977-01-01

    The albedo of the moon in the far UV was measured by Mariner 10 at a solar phase angle of 74 deg, and the geometric albedo of Mercury was measured in same wavelength range (584-1657 A) at solar phase angles ranging from 50 to 120 deg. For both the moon and Mercury there is a general increase in albedo for wavelengths decreasing from 1657 to 584 A. The ratio of the albedos of Mercury and the moon increases from about 0.6 to 0.8 in the range 600-1600 A. This merely points to a difference in the surfaces of the moon and Mercury, there being insufficient data to make any conclusions regarding the nature of the difference.

  14. Pseudo-random Spray Release to Measure World-wide Transfer Functions of Cloud Albedo Control.

    NASA Astrophysics Data System (ADS)

    Salter, Stephen

    2010-05-01

    Institute for Energy Systems, School of Engineering, University of Edinburgh. S.Salter@ed.ac.uk Previous climate models of Latham's proposal to reverse global warming by using sub-micron sea spray to increase cloud albedo have used a variety of spray patterns. Kettles forced CCN concentration to be 375/cm3 everywhere. Rasch et al used the 20% and 70% most susceptible regions. Bala and Caldeira used an even spread. Jones et al. concentrated spray in the 3.3% oceans with the highest susceptibility All used the same rate through the year. We want to choose a scheme for a climate-modelling experiment designed to identify simultaneously the effects of cloud albedo control at various seasons of the year from spray at all regions of the world on climates of all other regions the world. In particular we want to know seasons and spray places which might have an undesirable effect on precipitation. The spray systems in various regions of a numerical climate model will be modulated on an off with different but known pseudo-random sequences and a selection of seasons. The mean value of the resulting weather records of the parameters of interest, mainly temperature and water run-off, at each region will be subtracted from each value of the record so as to give just the alternating component with an average value of zero. This will be correlated with each of the chosen pseudo-random sequences to give the magnitude and polarity of the effect of a treatment at each input area and selected seasons of the year with the resulting effects on all regions. By doing a time-shifted correlation we can account for phase-shift and time delay. The signal-to-noise ratio should improve with the square root of the analysis time and so we may be able to measure the transfer function with quite a small stimulus. The results of a Mathcad simulation of the process with statistical distributions approximating to natural variations temperature and precipitation show that a single run of a climate

  15. Implications of albedo changes following afforestation on the benefits of forests as carbon sinks

    NASA Astrophysics Data System (ADS)

    Kirschbaum, M. U. F.; Whitehead, D.; Dean, S. M.; Beets, P. N.; Shepherd, J. D.; Ausseil, A.-G. E.

    2011-08-01

    Increased carbon storage with afforestation leads to a decrease in atmospheric carbon dioxide concentration and thus decreases radiative forcing and cools the Earth. However, land-use change also changes the reflective properties of the surface vegetation from more reflective pasture to relatively less reflective forest cover. This increase in radiation absorption by the forest constitutes an increase in radiative forcing, with a warming effect. The net effect of decreased albedo and carbon storage on radiative forcing depends on the relative magnitude of these two opposing processes. We used data from an intensively studied site in New Zealand's Central North Island that has long-term, ground-based measurements of albedo over the full short-wave spectrum from a developing Pinus radiata forest. Data from this site were supplemented with satellite-derived albedo estimates from New Zealand pastures. The albedo of a well-established forest was measured as 13 % and pasture