bluuebunny/crossref_metadata_2025 huggingface dataset:
Multidecadal variability of the continental precipitation annual amplitude driven by AMO and ENSO
Authors: García‐García David , Ummenhofer Caroline C.
Published: January 2015

As the water vapor content in the atmosphere scales with temperature, a warmer world is expected to feature an intensification of the hydrological cycle. Work to date has mainly focused on mean precipitation changes, whose connection to climatic modes is elusive at a global scale. Here we show that continental precipitation annual amplitude, which represents the annual range between minimum and maximum (monthly) rainfall, covaries with a linear combination of the Atlantic Multidecadal Oscillation and low‐frequency variations in the El Niño–Southern Oscillation on a decadal to multidecadal scale with a correlation coefficient of 0.92 (P < 0.01). The teleconnection is a result of changes in moisture transport in key regions. Reported trends in the annual amplitude of global precipitation in recent decades need to be assessed in light of this substantial low‐frequency variability, which could mask or enhance an anthropogenic signal in hydrological cycle changes.
Thickness of the crust of Mercury from geoid‐to‐topography ratios
Authors: Padovan Sebastiano , Wieczorek Mark A. , Margot Jean‐Luc , Tosi Nicola , Solomon Sean C.
Published: January 2015

To gain insight into the thickness of the crust of Mercury, we use gravity and topography data acquired by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft to calculate geoid‐to‐topography ratios over the northern hemisphere of the planet. For an Airy model for isostatic compensation of variations in topography, we infer an average crustal thickness of 35 ± 18 km. Combined with the value of the radius of the core of Mercury, this crustal thickness implies that Mercury had the highest efficiency of crustal production among the terrestrial planets. From the measured abundance of heat‐producing elements on the surface, we calculate that the heat production in the mantle from long‐lived radioactive elements at 4.45 Ga was greater than 5.4 ×10−12W/kg. By analogy with the Moon, the relatively thin crust of Mercury allows for the possibility that major impact events, such as the one that formed the Caloris basin, excavated material from Mercury's mantle.
Labile pyrogenic dissolved organic carbon in major Siberian Arctic rivers: Implications for wildfire‐stream metabolic linkages
Authors: Myers‐Pigg Allison N. , Louchouarn Patrick , Amon Rainer M. W. , Prokushkin Anatoly , Pierce Kayce , Rubtsov Alexey
Published: January 2015

Biomass burning produces a spectrum of thermally altered materials that releases pyrogenic carbon (PyC) to terrestrial, atmospheric, and aquatic systems. Most studies focus on the refractory end of the PyC spectrum, derived from middle‐ to high‐temperature combustion. Low‐temperature PyC is produced during wildfires and has been found to be particularly labile and water soluble. Here we find that in each of the major Siberian watersheds, low‐temperature fire‐derived biomarkers are present in detectable concentrations during all flow regimes of the 2004–2006 sampling period, confirming that PyC is an intrinsic component of the dissolved organic carbon (DOC) pool mobilized by hydrologic events. Gymnosperm combustion, from the southern portions of these watersheds, is the primary source of this Py‐DOC input. Using first‐order degradation rates and transit times of water through these rivers, about half of the total estimated flux of this material may be remineralized during transport from fire source to river mouth (20–40 days), demonstrating the input of a labile source of PyC to these watersheds.
Topside ionospheric irregularities as seen from multisatellite observations
Authors: Zakharenkova Irina , Astafyeva Elvira
Published: January 2015

We use in situ data from CHAMP and DMSP satellites, along with data of GPS receiver onboard CHAMP satellite and ground‐based GPS receivers to study the occurrence and global distribution of ionospheric irregularities during the main phase of the geomagnetic storm of 29–31 August 2004 (minimum Dst excursion of −128 nT). Using the CHAMP GPS measurements, we created maps of GPS phase fluctuation activity and found two specific zones of the most intense irregularities: (1) the region of the auroral oval at high latitudes of both hemispheres and (2) the low latitudes/equatorial region between Africa and South America. At high latitudes, the topside ionospheric irregularities appeared to be more intensive in the southern hemisphere, which is, most likely, due to seasonal variations in the interhemispheric field‐aligned currents system. An analysis of multi‐instrumental observations reveals reinforcement of the equatorial ionization anomaly after sunset in Atlantic sector on 30 August and formation of the significant plasma depletions and irregularities over a large longitudinal range. Equatorial irregularities were also found in the morning sector at the recovery phase of the storm. In addition to low Earth orbit (LEO) GPS measurements, we analyze the LEO in situ measurements, and we show that these two techniques cannot be interchangeable in all cases because of the altitudinal extent of plasma irregularities. Overall, we demonstrate that the LEO GPS technique can serve a useful tool for detection of the topside ionospheric irregularities during space weather events and may essentially contribute to other methods based on various instruments.
Acceleration of O+ from the cusp to the plasma sheet
Authors: Liao J. , Kistler L. M. , Mouikis C. G. , Klecker B. , Dandouras I.
Published: January 2015

Heavy ions from the ionosphere that are accelerated in the cusp/cleft have been identified as a direct source for the hot plasma in the plasma sheet. However, the details of the acceleration and transport that transforms the originally cold ions into the hot plasma sheet population are not fully understood. The polar orbit of the Cluster satellites covers the main transport path of the O+ from the cusp to the plasma sheet, so Cluster is ideal for tracking its velocity changes. However, because the cusp outflow is dispersed according to its velocity as it is transported to the tail, due to the velocity filter effect, the observed changes in beam velocity over the Cluster orbit may simply be the result of the spacecraft accessing different spatial regions and not necessarily evidence of acceleration. Using the Cluster Ion Spectrometry/Composition Distribution Function instrument onboard Cluster, we compare the distribution function of streaming O+ in the tail lobes with the initial distribution function observed over the cusp and reveal that the observations of energetic streaming O+ in the lobes around −20 RE are predominantly due to the velocity filter effect during nonstorm times. During storm times, the cusp distribution is further accelerated. In the plasma sheet boundary layer, however, the average O+ distribution function is above the upper range of the outflow distributions at the same velocity during both storm and nonstorm times, indicating that acceleration has taken place. Some of the velocity increase is in the direction perpendicular to the magnetic field, indicating that the E × B velocity is enhanced. However, there is also an increase in the parallel direction, which could be due to nonadiabatic acceleration at the boundary or wave heating.
The effect of direct electron‐positron pair production on relativistic feedback rates
Authors: Vodopiyanov I. B. , Dwyer J. R. , Cramer E. S. , Lucia R. J. , Rassoul H. K.
Published: January 2015

Runaway electron avalanches developing in thunderclouds in high electric field become self‐sustaining due to relativistic feedback via the production of backward propagating positrons and backscattered X‐rays. To date, only positrons created from pair production by gamma rays interacting with the air have been considered. In contrast, direct electron‐positron pair production, also known as “trident process,” occurs from the interaction of energetic runaway electrons with atomic nuclei, and so it does not require the generation of a gamma ray mediator. The positrons produced in this process contribute to relativistic feedback and become especially important when the feedback factor value approaches unity. Then the steady state flux of runaway electrons increases significantly. In certain cases, when the strong electrostatic field forms in a narrow area, the direct positrons become one of processes dominating relativistic feedback. Calculations of the direct positron production contribution to relativistic feedback are presented for different electric field configurations.
Magnetic field power spectra and magnetic radial diffusion coefficients using CRRES magnetometer data
Authors: Ali Ashar F. , Elkington Scot R. , Tu Weichao , Ozeke Louis G. , Chan Anthony A. , Friedel Reiner H. W.
Published: January 2015

We used the fluxgate magnetometer data from Combined Release and Radiation Effects Satellite (CRRES) to estimate the power spectral density (PSD) of the compressional component of the geomagnetic field in the ∼1 mHz to ∼8 mHz range. We conclude that magnetic wave power is generally higher in the noon sector for quiet times with no significant difference between the dawn, dusk, and the midnight sectors. However, during high Kp activity, the noon sector is not necessarily dominant anymore. The magnetic PSDs have a very distinct dependence on Kp. In addition, the PSDs appear to have a weak dependence on McIlwain parameter L with power slightly increasing as L increases. The magnetic wave PSDs are used along with the Fei et al. (2006) formulation to compute as a function of L and Kp. The L dependence of is systematically studied and is shown to depend on Kp. More significantly, we conclude that is the dominant term driving radial diffusion, typically exceeding by 1–2 orders of magnitude.
On the solar activity variations of nocturnal F region vertical drifts covering two solar cycles in the Indian longitude sector
Authors: Madhav Haridas M. K. , Manju G. , Pant Tarun Kumar
Published: January 2015

A comprehensive analysis of the seasonal and solar cycle variabilities of nighttime vertical drift over the Indian longitude sector is accomplished using ionosonde data located at the magnetic equatorial location, Trivandrum (8.5°N, 76.5°E). The analysis extends over a span of two decades (1988–2008). The representative seasonal variations based on the extensive data of nocturnal vertical drift during three different solar activity epochs is arrived at, for the first time. Seasonally, it is seen that maximum post sunset Vd is obtained in vernal equinox (VE), followed by autumnal equinox (AE), winter solstice (WS), and summer solstice (SS) for high and moderate solar epochs, while for low solar epoch, maximum Vd occurs in WS followed by VE, AE, and SS. Further, the role of sunset times at the magnetic conjugate points in modulating the time and magnitude of peak drifts during different solar epochs is ascertained. The equinoctial asymmetry in peak Vd during high and moderate solar epochs is another significant outcome of this study. The solar activity dependence of vertical drift for a wide range of solar fluxes has been quantified for all the seasons. In the present era of GPS‐based communication and navigation, these are important results that give a better handle in understanding essential factors that impact equatorial ionospheric phenomena.
The annual asymmetry in the F2 layer during deep solar minimum (2008–2009): December anomaly
Authors: Mikhailov A. V. , Perrone L.
Published: January 2015

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.
Thermal perturbations beneath the incipient Okavango Rift Zone, northwest Botswana
Authors: Leseane Khumo , Atekwana Estella A. , Mickus Kevin L. , Abdelsalam Mohamed G. , Shemang Elisha M. , Atekwana Eliot A.
Published: January 2015

We used aeromagnetic and gravity data to investigate the thermal structure beneath the incipient Okavango Rift Zone (ORZ) in northwestern Botswana in order to understand its role in strain localization during rift initiation. We used three‐dimensional (3‐D) inversion of aeromagnetic data to estimate the Curie Point Depth (CPD) and heat flow under the rift and surrounding basement. We also used two‐dimensional (2‐D) power‐density spectrum analysis of gravity data to estimate the Moho depth. Our results reveal shallow CPD values (8–15 km) and high heat flow (60–90 mW m−2) beneath a ~60 km wide NE‐trending zone coincident with major rift‐related border faults and the boundary between Proterozoic orogenic belts. This is accompanied by thin crust (<30 km) in the northeastern and southwestern parts of the ORZ. Within the Precambrian basement areas, the CPD values are deeper (16–30 km) and the heat flow estimates are lower (30–50 mW m−2), corresponding to thicker crust (~40–50 km). We interpret the thermal structure under the ORZ as due to upward migration of hot mantle fluids through the lithospheric column that utilized the presence of Precambrian lithospheric shear zones as conduits. These fluids weaken the crust, enhancing rift nucleation. Our interpretation is supported by 2‐D forward modeling of gravity data suggesting the presence of a wedge of altered lithospheric mantle centered beneath the ORZ. If our interpretation is correct, it may result in a potential paradigm shift in which strain localization at continental rift initiation could be achieved through fluid‐assisted lithospheric weakening without asthenospheric involvement.
Seismic anisotropy indicates ridge‐parallel asthenospheric flow beneath the Eastern Lau Spreading Center
Authors: Menke William , Zha Yang , Webb Spahr C. , Blackman Donna K.
Published: January 2015

Seismic anisotropy beneath the Eastern Lau Spreading Center (ELSC) is investigated using both Rayleigh waves and shear waves, using data from the 2009–2010 ELSC ocean bottom seismograph experiment. Phase velocities of Rayleigh waves determined by ambient noise cross correlation are inverted for azimuthally anisotropic phase velocity maps. Splitting of S waves from five intermediate and deep focus earthquakes was determined by waveform analysis. Taken together, Rayleigh wave and S wave data indicate that significant (~2%) anisotropy extends to at least 300 km depth. Both data sets indicate a fast direction aligned within a few degrees of the N10°E striking ELSC and somewhat oblique to the N25°E strike of the neighboring volcanic arc. We therefore describe the fast direction as spreading perpendicular, not convergence perpendicular and interpret it as due to ridge‐parallel flow of the asthenosphere. However, the region arcward (east) of the ELSC has the stronger anisotropy, suggesting that the strongest flow gradients may occur in the region between the spreading center and the arc, in contrast to being centered beneath the ELSC. Fluids released from the underlying plate may produce anisotropic hydrous materials, but more importantly lower the viscosity, thus enhancing along‐strike flow. Both could contribute to an along‐strike fast direction signature. Seafloor spreading diminishes south of the seismic array, ceasing altogether south of latitude 25°S (500 km south of the array center), a region dominated by much slower tectonic extension, suggesting that asthenosphere is inflowing from the north to accommodate the increase in asthenospheric volume associated with the seafloor spreading.
An integrated paleomagnetic, rock magnetic, and geochemical study of the Marcellus shale in the Valley and Ridge province in Pennsylvania and West Virginia
Authors: Manning Earl Berry , Elmore R. D.
Published: January 2015

An integrated paleomagnetic, rock magnetic, and diagenetic study of the Devonian Marcellus Subgroup from threefolds in the Valley and Ridge province in Pennsylvania and West Virginia indicates that the unit contains an intermediate temperature chemical remanent magnetization (CRM) with south‐southeast declinations and shallow negative inclinations residing in pyrrhotite and a CRM with more southerly declinations and shallow positive inclinations residing in magnetite. Rock magnetic results confirm the presence of pyrrhotite and magnetite. Tilt tests indicate that pyrrhotite and magnetite CRMs are syntilting to posttilting, and paleopoles for both CRMs are similar and plot on the Permian part of the apparent polar wander path for North America. The Marcellus Subgroup has a complex paragenetic sequence which includes bitumen deposition and vein formation. The magnetite and pyrrhotite CRMs formed in the Permian, probably due to burial diagenetic processes and not orogenic fluids. The base of the unit contains the highest total organic content (TOC) values and highest magnetic intensities, both of which decrease up section. This connection between TOC and magnetic intensity suggests that the magnetite formed as a result of the maturation of the organic matter although more work is needed to test this hypothesis. The pyrrhotite may have formed as a result of thermochemical sulfate reduction involving organic matter during the production of methane in this gas reservoir. The similar Permian CRM ages may be explained by thrusting which resulted in rapid burial of the Marcellus Subgroup as it passed through the oil window and into the gas window quickly producing magnetite and pyrrhotite, respectively.
Mechanical stability model of progradational carbonate platform margins under tectonic loads: Deformation of Cretaceous carbonate platforms in the Sierra Madre Oriental fold‐thrust belt (east central Mexico)
Authors: Contreras Juan , Suter Max
Published: January 2015

Shortening in the Sierra Madre Oriental fold‐thrust belt (east central Mexico) is localized along the margins of Cretaceous carbonate platforms and controlled by mechanical stratigraphy. The platform margins are deformed by imbricate series of thrust ramps, whereas the coeval basins and platform interiors are deformed by map‐scale detachment folds. Here we present a finite element model to evaluate the influence of the boundary geometry and boundary conditions on the style of deformation observed at these basinward progradational platform margins. We calculate the stress distribution in a linearly elastic platform‐basin transition zone under the action of horizontal tectonic stress, taking into account changes of rock mechanical properties across the platform margin, as well as their dependence on direction, and infer the resulting fracture patterns based on the Mohr‐Coulomb failure criterion. Stress concentrations are predicted at the contacts between the massive rocks of the platform margin and the well‐layered rocks of both, the platform interior and the adjacent basin. Brittle failure of the platform border can be mostly attributed to three effects: mechanical coupling between the carbonate platform and a substratum of moderate to low viscosity, variations in layering and texture that governed the mechanical properties of the involved carbonates as well as their dependence on direction, and the development of sharp domain boundary corners associated with progradational facies changes. In contrast, the dip of the basement and a possible taper of the overlying Upper Cretaceous shale toward the basin appear to have little influence on the mechanical failure of the platform margin.
Long‐term TIR imagery processing for spatiotemporal monitoring of surface thermal features in volcanic environment: A case study in the Campi Flegrei (Southern Italy)
Authors: Vilardo G. , Sansivero F. , Chiodini G.
Published: January 2015

Different procedures were used to analyze a comprehensive time series of nighttime thermal infrared images acquired from October 2006 to June 2013 by a permanent station at Pisciarelli (Campi Flegrei, Italy). The methodologies were aimed at the detection and quantification of possible spatiotemporal changes in the ground‐surface thermal features of an area affected by diffuse degassing. Long‐term infrared time series images were processed without taking into account atmospheric conditions and emissivity estimations. The data obtained were compared with the trends of independent geophysical and geochemical parameters, which suggested that long‐term temporal variations of the surface maximum temperatures were governed by the dynamics of the deeper hydrothermal system. Analogously, the dynamics of the shallow hydrothermal system are likely to control the short‐period thermal oscillations that overlie the long‐term thermal signals. The map of the yearly rates of temperature change shows temperature increases clustered in the thermal anomalous area of the infrared images, without evidence of modifications to the extension of the anomaly or of growth of new areas with significant thermal emission. This suggests that in the present state, the heat transfer is mainly due to hot gas emission through preexisting fractures and vents. Our data indicate that the comprehensive picture of the spatiotemporal evolution of the thermal features of the hydrothermal sites obtained by long‐term infrared monitoring can provide useful information toward refining physical and conceptual models, as well as improving surveillance of active volcanoes.
The role of lithological layering and pore pressure on fluid‐induced microseismicity
Authors: Roche V. , van der Baan M.
Published: January 2015

The success of hydraulic fracturing treatments is often judged by the shape and size of the resulting microseismic cloud. However, it is challenging to predict the anticipated microseismic cloud prior to treatment. We use geomechanical modeling to predict the distribution of the microseismicity prior to the hydraulic fracture treatment. We analyze the likelihood of tensile and shear failure due to 1‐D variations in local stresses and rock strengths, induced by layering and pore pressure, for two field cases. The deviation in the local stresses from the regional stress field is induced by vertical variations in stiffness. This promotes failure of the stronger layers instead of the weaker ones since the stronger layers can become essentially load bearing. The simulations and field studies show that (1) microseismic events tend to locate preferentially where layers reach tensile failure due to fluid injection, and the number of events tends to decrease in layers that do not reach tensile failure; (2) shear initiation can occur in different layers from those failing in tension, thereby creating additional fluid migration paths; and (3) reactivation of preexisting fractures may occur due to fluid migration, even if their orientations are unfavorable. Numerical modeling is a significant aid in understanding the interplay of regional and local stresses and associated in situ failure due to variations in rock strength, pore pressure, and stiffnesses. In a wider perspective, it gives fundamental insights into the understanding of earthquakes and fault localization, the mechanisms of fracture development, and the role of fractures on fluid circulation and on the in situ stress field.
The refreezing of melt ponds on Arctic sea ice
Authors: Flocco Daniela , Feltham Daniel L. , Bailey Eleanor , Schroeder David
Published: January 2015

The presence of melt ponds on the surface of Arctic sea ice significantly reduces its albedo, inducing a positive feedback leading to sea ice thinning. While the role of melt ponds in enhancing the summer melt of sea ice is well known, their impact on suppressing winter freezing of sea ice has, hitherto, received less attention. Melt ponds freeze by forming an ice lid at the upper surface, which insulates them from the atmosphere and traps pond water between the underlying sea ice and the ice lid. The pond water is a store of latent heat, which is released during refreezing. Until a pond freezes completely, there can be minimal ice growth at the base of the underlying sea ice. In this work, we present a model of the refreezing of a melt pond that includes the heat and salt balances in the ice lid, trapped pond, and underlying sea ice. The model uses a two‐stream radiation model to account for radiative scattering at phase boundaries. Simulations and related sensitivity studies suggest that trapped pond water may survive for over a month. We focus on the role that pond salinity has on delaying the refreezing process and retarding basal sea ice growth. We estimate that for a typical sea ice pond coverage in autumn, excluding the impact of trapped ponds in models overestimates ice growth by up to 265 million km3, an overestimate of 26%.
Typhoon air‐sea drag coefficient in coastal regions
Authors: Zhao Zhong‐Kuo , Liu Chun‐Xia , Li Qi , Dai Guang‐Feng , Song Qing‐Tao , Lv Wei‐Hua
Published: January 2015

The air‐sea drag during typhoon landfalls is investigated for a 10 m wind speed as high as U10 ≈ 42 m s−1, based on multilevel wind measurements from a coastal tower located in the South China Sea. The drag coefficient (CD) plotted against the typhoon wind speed is similar to that of open ocean conditions; however, the CD curve shifts toward a regime of lower winds, and CD increases by a factor of approximately 0.5 relative to the open ocean. Our results indicate that the critical wind speed at which CD peaks is approximately 24 m s−1, which is 5–15 m s−1 lower than that from deep water. Shoaling effects are invoked to explain the findings. Based on our results, the proposed CD formulation, which depends on both water depth and wind speed, is applied to a typhoon forecast model. The forecasts of typhoon track and surface wind speed are improved. Therefore, a water‐depth‐dependence formulation of CD may be particularly pertinent for parameterizing air‐sea momentum exchanges over shallow water.
Modeling skin‐layer salinity with an extended surface‐salinity layer
Authors: Song Y. Tony , Lee Tong , Moon Jae‐Hong , Qu Tangdong , Yueh Simon
Published: January 2015

Due to near‐surface salinity stratification, it is problematic to compare satellite‐measured surface salinity within the first few centimeters (skin‐layer) of the ocean with Argo‐measured top‐level salinity at about 5 m or with ocean models that do not resolve the skin layer. Although an instrument can be designed to measure the surface salinity, a global scale measurement is currently not available. A regional model can be configured to have a vertical grid in centimeters but it would be computationally prohibited on a global scale due to time step constraints. Here we propose an extended surface‐salinity layer (ESSL) within a global ocean circulation model to diagnose skin SSS without increasing the computational cost, while allowing comparable solutions with both satellite and Argo salinity at the respective depths. Using a quarter‐degree global ocean model, we show that the ESSL improves near‐surface salinity significantly in comparisons with the Aquarius SSS and Argo salinity at 5 and 10 m, respectively. Comparing with data‐assimilated HYCOM results reveal that the ESSL provides much stronger seasonal variability of SSS, similar to the Aquarius observations. We also demonstrate that the ESSL solution can be used to constrain the global mean SSS in Aquarius SSS retrieval.
Spatial and temporal variability of freshwater discharge into the Gulf of Alaska
Authors: Hill D. F. , Bruhis N. , Calos S. E. , Arendt A. , Beamer J.
Published: January 2015

A study of the freshwater discharge into the Gulf of Alaska (GOA) has been carried out. Using available streamgage data, regression equations were developed for monthly flows. These equations express discharge as a function of basin physical characteristics such as area, mean elevation, and land cover, and of basin meteorological characteristics such as temperature, precipitation, and accumulated water year precipitation. To provide the necessary input meteorological data, temperature and precipitation data for a 40 year hind‐cast period were developed on high‐spatial‐resolution grids using weather station data, PRISM climatologies, and statistical downscaling methods. Runoff predictions from the equations were found to agree well with observations. Once developed, the regression equations were applied to a network of delineated watersheds spanning the entire GOA drainage basin. The region was divided into a northern region, ranging from the Aleutian Chain to the Alaska/Canada border in the southeast panhandle, and a southern region, ranging from there to the Fraser River. The mean annual runoff volume into the northern GOA region was found to be 792 ± 120 km3 yr−1. A water balance using MODIS‐based evapotranspiration rates yielded seasonal storage volumes that were consistent with GRACE satellite‐based estimates. The GRACE data suggest that an additional 57 ± 11 km3 yr−1 be added to the runoff from the northern region, due to glacier volume loss (GVL) in recent years. This yields a total value of 849 ± 121 km3 yr−1. The ease of application of the derived regression equations provides an accessible tool for quantifying mean annual values, seasonal variation, and interannual variability of runoff in any ungaged basin of interest.
Detectability of CO2 flux signals by a space‐based lidar mission
Authors: Hammerling Dorit M. , Kawa S. Randolph , Schaefer Kevin , Doney Scott , Michalak Anna M.
Published: January 2015

Satellite observations of carbon dioxide (CO2) offer novel and distinctive opportunities for improving our quantitative understanding of the carbon cycle. Prospective observations include those from space‐based lidar such as the active sensing of CO2 emissions over nights, days, and seasons (ASCENDS) mission. Here we explore the ability of such a mission to detect regional changes in CO2 fluxes. We investigate these using three prototypical case studies, namely, the thawing of permafrost in the northern high latitudes, the shifting of fossil fuel emissions from Europe to China, and changes in the source/sink characteristics of the Southern Ocean. These three scenarios were used to design signal detection studies to investigate the ability to detect the unfolding of these scenarios compared to a baseline scenario. Results indicate that the ASCENDS mission could detect the types of signals investigated in this study, with the caveat that the study is based on some simplifying assumptions. The permafrost thawing flux perturbation is readily detectable at a high level of significance. The fossil fuel emission detectability is directly related to the strength of the signal and the level of measurement noise. For a nominal (lower) fossil fuel emission signal, only the idealized noise‐free instrument test case produces a clearly detectable signal, while experiments with more realistic noise levels capture the signal only in the higher (exaggerated) signal case. For the Southern Ocean scenario, differences due to the natural variability in the El Niño–Southern Oscillation climatic mode are primarily detectable as a zonal increase.
Dust detection from ground‐based observations in the summer global dust maximum: Results from Fennec 2011 and 2012 and implications for modeling and field observations
Authors: Allen Christopher J. T. , Washington R. , Saci A.
Published: January 2015

In boreal summer, the central Sahara is the dustiest place on Earth. Fennec supersite 1 is located within the dust maximum. With two field seasons completed, June 2011 (intensive observation period (IOP) 1) and June 2012 (IOP2), we now have an initial measure of their representativeness. Although the number of dust event hours in IOP2 is up to 169 h (60%) more than in IOP1, the relative importance of the different dust mechanisms is the same. In both years, emission by cold pool outflows from deep convection causes most dust, followed by dust advection, monsoon surges, low‐level jet emission and lastly dry convective plumes. Given the dominance of cold pools, it is very important that they be incorporated in dust modeling efforts over the region. Because cold pools frequently occur at night and are associated with cloud cover, instruments that can monitor in these conditions are particularly valuable in this region. Sun photometer aerosol optical depth retrievals, for example, are only available for 23% (41%) of the time cold pool emission occurs at the supersite in IOP1 (IOP2). Deployment of instrumentation in remote regions being difficult and expensive, choosing the optimal instrument payload pays dividends. With this motivation, we evaluate the different dust detection instrumentation deployed at the supersite and develop an approach which can identify and characterize individual dust emission mechanisms with a high degree of success purely from routine meteorological observations and remote sensing. This identification is, however, much more challenging in the case of dust advection.
Water and entrapped air redistribution in heterogeneous sand sample: Quantitative neutron imaging of the process
Authors: Snehota Michal , Jelinkova Vladimira , Sobotkova Martina , Sacha Jan , Vontobel Peter , Hovind Jan
Published: January 2015

Saturated flow in soil with the occurrence of preferential flow often exhibits temporal changes of saturated hydraulic conductivity even during the time scale of a single infiltration event. These effects, observed in a number of experiments done mainly on heterogeneous soils, are often attributed to the changing distribution of water and air in the sample. We have measured the variation of the flow rates during the steady state stage of the constant head ponded infiltration experiment conducted on a packed sample composed of three different grades of sand. The experiment was monitored by quantitative neutron imaging, which provided information about the spatial distribution of water in the sample. Measurements were taken during (i) the initial stages of infiltration by neutron radiography and (ii) during the steady state flow by neutron tomography. A gradual decrease of the hydraulic conductivity has been observed during the first 4 h of the infiltration event. A series of neutron tomography images taken during the quasi‐steady state stage showed the trapping of air bubbles in coarser sand. Furthermore, the water content in the coarse sand decreased even more while the water content in the embedded fine sand blocks gradually increased. The experimental results support the hypothesis that the effect of the gradual hydraulic conductivity decrease is caused by entrapped air redistribution and the build up of bubbles in preferential pathways. The trapped air thus restricts the preferential flow pathways and causes lower hydraulic conductivity.
A physically based surface resistance model for evaporation from bare soils
Authors: Zhang Chenming , Li Ling , Lockington David
Published: January 2015

The resistance to vapor transfer across the soil‐air interface, termed surface resistance, plays an important role in determining the evaporation rate from unsaturated bare soils. A physically based analytical model is developed to describe the surface resistance under varying liquid water saturation. When the vaporization plane remains in the topmost soil layer (TSL), the model considers the vapor transport through the external diffusive layer (EDL), and the hydraulic connection between the capillary water in the TSL and underneath water source for evaporation. When the vaporization plane develops below the TSL, the model predicts the surface resistance by taking into account the development of the dry soil layer, the major barrier for vapor transport at the soil‐drying stage. With the consideration of the soil pore size distribution, the model is applicable to different soil types. The model was validated against six sets of laboratory experiments on the drying process of initially water‐saturated soil columns under nonisothermal conditions. These experiments were conducted using different soil types and/or heat intensities above the soil surface. The model was found to perform well over intermediate and low liquid water saturation ranges while underestimating the surface resistance for the high liquid water saturation range. The results suggest that the model overall represents reasonably well the processes underlying the vapor transfer across the soil‐air interface. Future model improvement may be gained by considering the hydraulic connection between the capillary water and film water in the TSL.
Hydrophobic organic contaminant transport property heterogeneity in the Borden Aquifer
Authors: Allen‐King Richelle M. , Kalinovich Indra , Dominic David F. , Wang Guohui , Polmanteer Reid , Divine Dana
Published: January 2015

We determined that the spatial heterogeneity in aquifer properties governing the reactive transport of volatile organic contaminants is defined by the arrangement of lithofacies. We measured permeability (k) and perchloroethene sorption distribution coefficient (Kd) for lithofacies that we delineated for samples from the Canadian Forces Base Borden Aquifer. We compiled existing data and collected 57 new cores to characterize a 30 m section of the aquifer near the test location of Mackay et al. (1986). The k and Kd were measured for samples taken at six elevations from all cores to create a data set consisting of nearly 400 colocated measurements. Through analysis of variance (corrected for multiple comparisons), we determined that the 12 originally mapped lithofacies could be grouped into five relatively distinct chemohydrofacies that capture the variability of both transport properties. The mean of ln k by lithofacies was related to the grain size and the variance was relatively consistent. In contrast, both the mean and variance of ln Kd were greater for more poorly sorted lithofacies, which were also typically more coarse‐grained. Half of the aquifer sorption capacity occurred in the three highest‐sorbing lithofacies but comprised only 20% of its volume. The model of the aquifer that emerged is that of discontinuous scour‐fill deposits of medium sand, generally characterized by greater Kd and k, within laterally extensive fine‐grained to very fine‐grained sands of lower Kd and k. Our findings demonstrate the importance of considering source rock composition, transport, and deposition processes when constructing conceptual models of chemohydrofacies.
The avascular zone and neuronal remodeling of the fovea in Parkinson disease
Authors: Miri Shahnaz , Shrier Eric M. , Glazman Sofya , Ding Yin , Selesnick Ivan , Kozlowski Piotr B. , Bodis‐Wollner Ivan
Published: January 2015

Inner foveal thinning and intracellular alpha‐synuclein were demonstrated in the retina in Parkinson disease. While pathognomonic alpha‐synuclein is associated with embryonic dopaminergic (DA) neurons, postmortem studies in the nervous system and retina show prominent effect also in non‐DA neurons. We evaluated foveal capillaries and foveal thickness in 23 Parkinson disease subjects and 13 healthy controls using retinal fluorescein angiography and optical coherence tomography. The size of the foveal avascular zone inversely correlates with foveal thinning. Foveal thinning highly correlates with motor impairment and also disease duration. Quantifying capillary and neuronal remodeling could serve as biological markers.
Negative Emotions Felt During Trial: the Effect of Fear, Anger, and Sadness on Juror Decision Making
Authors: Nuñez Narina , Schweitzer Kimberly , Chai Christopher A. , Myers Bryan
Published: January 2015

During trial, jurors may experience a variety of emotions, many of which are negative. The current study examined the effects the negative emotions anger, fear, and sadness had on jurors' sentencing decisions and explored whether the cognitive appraisal theory or the intuitive prosecutor model could explain these effects. Jurors viewed the sentencing phase of a capital murder trial and were asked to sentence the defendant. Results indicated that after viewing the trial, jurors reported increased anger and sadness, but not fear. However, only change in anger affected jurors' sentences. Jurors who reported a greater change in anger were more likely to sentence the defendant to death. This effect was mediated by the level of importance that jurors placed on the prosecution's evidence and argument. Consistent with the intuitive prosecutor model, increased anger led to higher ratings of the importance of the aggravating evidence and an increase in death sentences. Implications are discussed. Copyright © 2015 John Wiley & Sons, Ltd.
Sex Really Does Sell: The Recall of Sexual and Non‐sexual Television Advertisements in Sexual and Non‐sexual Programmes
Authors: King James , McClelland Alastair , Furnham Adrian
Published: January 2015

The present study examined memory for advertisements as a function of both advertisement content and the contextual programme content. Participants were randomly assigned to one of two conditions: in one condition, they watched a sexual programme and in the other a non‐sexual programme. Embedded within each programme were the same highly sexual and non‐sexual advertisements that had been matched in pairs for five products. Memory for the advertisements and involvement in the programmes was measured. It was found that on three indices (free recall, brand recognition and prompted recall), memory for the sexual advertisements was superior to that for non‐sexual advertisements. There was no effect of the programme content on advertisement recall and no relationship between programme involvement and advertisement recall. The results are discussed with reference to extant literature on memory for advertisements. Copyright © 2015 John Wiley & Sons, Ltd.
Edge‐Fluorinated Graphene Nanoplatelets as High Performance Electrodes for Dye‐Sensitized Solar Cells and Lithium Ion Batteries
Authors: Jeon In‐Yup , Ju Myung Jong , Xu Jiantie , Choi Hyun‐Jung , Seo Jeong‐Min , Kim Min‐Jung , Choi In Taek , Kim Hong Mo , Kim Jae Cheon , Lee Jae‐Joon , Liu Hua Kun , Kim Hwan Kyu , Dou Shixue , Dai Liming , Baek Jong‐Beom
Published: January 2015

Edge‐selectively fluorinated graphene nanoplatelets (FGnPs) are prepared by mechanochemically driven reaction between fluorine gas (20 vol% in argon) and activated carbon species from graphitic C–C bonds unzipped by high‐speed stainless steel balls with a high kinetic energy. The fluorination at edges of the unzipped graphene nanoplatelets (GnPs) is confirmed by various analytical techniques while the content of fluorine in FGnPs is determined to be 3.0 and 3.4 at% by X‐ray photoelectron spectroscopy and energy‐dispersive X‐ray spectroscopy, respectively. Because of the large difference in electronegativity between carbon (χ = 2.55) and fluorine (χ = 3.98) and the strong C–F bond, the edge‐fluorination of GnPs can provide the maximized charge polarization with an enhanced chemical stability. Thus, electrodes based on the resultant FGnPs demonstrate superb electrochemical performance with excellent stability/cycle life in dye‐sensitized solar cells (FF: 71.5%; Jsc: 14.44 mA cm−2; Voc: 970 mV; PCE: 10.01%) and lithium ion batteries (650.3 mA h g−1 at 0.5 C, charge retention of 76.6% after 500 cycles).
One‐Pot, Facile, and Versatile Synthesis of Monolayer MoS2/WS2 Quantum Dots as Bioimaging Probes and Efficient Electrocatalysts for Hydrogen Evolution Reaction
Authors: Xu Shengjie , Li Dian , Wu Peiyi
Published: January 2015

In this work, uniform molybdenum disulfide (MoS2)/tungsten disulfide (WS2) quantum dots are synthesized by the combination of sonication and solvothermal treatment of bulk MoS2/WS2 at a mild temperature. The resulting products possess monolayer thickness with an average size about 3 nm. The highly exfoliated and defect‐rich structure renders these quantum dots plentiful active sites for the catalysis of hydrogen evolution reaction (HER). The MoS2 quantum dots exhibit a small HER overpotential of ≈120 mV and long‐term durability. Moreover, the strong fluorescence, good cell permeability, and low cytotoxicity make them promising and biocompatible probes for in vitro imaging. In addition, this work may provide an alternative facile approach to synthesize the quantum dots of transition metal dichalcogenides or other layered materials on a large scale.
Rhodium(III)‐Catalyzed ortho‐Arylation of Anilides with Aryl Halides
Authors: Haridharan Radhakrishnan , Muralirajan Krishnamoorthy , Cheng Chien‐Hong
Published: January 2015

An efficient o‐arylation of pivalamides by aryl iodides via rhodium(III)‐catalyzed C–H activation is demonstrated for the first time. Further, the biaryl products can be converted effectively into biologically active phenanthridine and phenanthridinone derivative.

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Improved Power Conversion Efficiency of P3HT:PCBM Organic Solar Cells by Strong Spin–Orbit Coupling‐Induced Delayed Fluorescence
Authors: González Daniel Moseguí , Körstgens Volker , Yao Yuan , Song Lin , Santoro Gonzalo , Roth Stephan V. , Müller‐Buschbaum Peter
Published: January 2015

Solution‐processed organic bulk heterojunction solar cells based on poly(3‐hexylthiophene) (P3HT) blended with [6,6]‐phenyl‐C60‐butyric acid methyl ester are doped with different concentrations of iron (II,III) oxide nanoparticles (Fe3O4). The power conversion efficiency of the devices doped at low concentrations is improved up to 11%. The improvement finds its origin in a lower recombination current, which is a consequence of an increased effective exciton lifetime according to the J–V characteristics and the optoelectronical analysis of the films. The increase in performance cannot be attributed to changes in morphology or crystallinity according to grazing‐incidence X‐ray scattering experiments. The evolution of the solar cell short‐circuit current at low doping concentrations is related to variations in the arrangement of the crystalline regions of P3HT. For high doping concentrations (above 1.0 wt%) the performance of the solar cell decays rapidly, ascribed to the increased leakage currents in the device caused by the presence of nanoparticles.