bluuebunny/crossref_metadata_2025_split huggingface dataset:
Seasonal evolution of the QBO‐induced wave forcing and circulation anomalies in the northern winter stratosphere
Authors: White Ian P. , Lu Hua , Mitchell Nicholas J. 
Published: August 2016

AbstractDiagnostics of wave‐mean‐flow and wave‐wave interactions in isentropic coordinates are analyzed regarding the mechanisms that govern the Holton‐Tan effect (HTE), whereby the tropical quasi‐biennial oscillation (QBO) modulates the northern winter stratospheric polar vortex. We find a clear seasonal evolution of a QBO modulation of Rossby waves and linear and nonlinear wave interactions, along with multiple mechanisms at work. In early winter, when the lower stratospheric QBO is easterly, there is enhanced upward stationary planetary‐wave activity in the subtropical to midlatitude lower stratosphere. These upward‐propagating waves are first refracted toward the zero‐wind line. Approximately 1 month later, poleward‐propagating wave anomalies appear at midlatitudes as a result of nonlinear wave interactions. The enhanced upward wave propagation appears to be due to a combination of the QBO influence on the latitudinal location of the zero‐wind line and the increased midlatitude baroclinicity associated with the QBO‐induced meridional circulation. This is further aided by a gradual poleward shift over the winter of the middle‐stratospheric waveguide, refracting waves poleward. The associated wave breaking weakens the polar vortex and drives a stronger meridional circulation throughout the lower to middle stratosphere, contributing to the high‐latitude warming. It is additionally found that in late winter, the modified high‐latitude waveguide associated with the weaker polar vortex, consequently reduces upward‐propagating transient planetary waves at high latitudes while simultaneously enhancing upward‐propagating synoptic waves at midlatitudes. This highlights the need to view the HTE and its mechanisms as an evolving phenomenon throughout the winter.
Investigation into the impact of storms on sustaining summer primary productivity in the Sub‐Antarctic Ocean
Authors: Nicholson Sarah‐Anne , Lévy Marina , Llort Joan , Swart Sebastiaan , Monteiro Pedro M. S. 
Published: August 2016

AbstractIn the Sub‐Antarctic Ocean elevated phytoplankton biomass persists through summer at a time when productivity is expected to be low due to iron limitation. Biological iron recycling has been shown to support summer biomass. In addition, we investigate an iron supply mechanism previously unaccounted for in iron budget studies. Using a 1‐D biogeochemical model, we show how storm‐driven mixing provides relief from phytoplankton iron limitation through the entrainment of iron beneath the productive layer. This effect is significant when a mixing transition layer of strong diffusivities (kz > 10−4 m2 s−1) is present beneath the surface‐mixing layer. Such subsurface mixing has been shown to arise from interactions between turbulent ocean dynamics and storm‐driven inertial motions. The addition of intraseasonal mixing yielded increases of up to 60% in summer primary production. These results stress the need to acquire observations of subsurface mixing and to develop the appropriate parameterizations of such phenomena for ocean‐biogeochemical models.
Swelling‐induced changes in coal microstructure due to supercritical CO2 injection
Authors: Zhang Yihuai , Lebedev Maxim , Sarmadivaleh Mohammad , Barifcani Ahmed , Iglauer Stefan 
Published: August 2016

AbstractEnhanced coalbed methane recovery and CO2 geostorage in coal seams are severely limited by permeability decrease caused by CO2 injection and associated coal matrix swelling. Typically, it is assumed that matrix swelling leads to coal cleat closure, and as a consequence, permeability is reduced. However, this assumption has not yet been directly observed. Using a novel in situ reservoir condition X‐ray microcomputed tomography flooding apparatus, for the first time we observed such microcleat closure induced by supercritical CO2 flooding in situ. Furthermore, fracturing of the mineral phase (embedded in the coal) was observed; this fracturing was induced by the internal swelling stress. We conclude that coal permeability is drastically reduced by cleat closure, which again is caused by coal matrix swelling, which again is caused by flooding with supercritical CO2.
Spectral characteristics of steady quiet‐time EMIC waves observed at geosynchronous orbit
Authors: Kim Khan‐Hyuk , Park Jong‐Sun , Omura Yoshiharu , Shiokawa Kazuo , Lee Dong‐Hun , Kim Gi‐Jeong , Jin Ho , Lee Ensang , Kwon Hyuck‐Jin 
Published: August 2016

AbstractWe have studied the spectral properties of quiet‐time electromagnetic ion cyclotron (EMIC) waves following a steady quiet condition, which is defined with Kp values ≤1 during 12 h, using GOES 10, 11, and 12 magnetometer data for solar minimum years 2007–2008. We identified 6584 steady quiet‐time EMIC wave samples using a semiautomated procedure. Approximately 82% of the samples were observed in the morning‐to‐early afternoon sector (0700–1500 magnetic local time) with a maximum occurrence near noon, and their peak frequencies were mostly in the He band. We found that the occurrence rate of steady quiet‐time EMIC waves is higher than that of EMIC waves for all or quiet geomagnetic conditions (Dst > 0 nT or AE < 100 nT) reported in previous studies by a factor of 2 or more. The frequency ratio fpeak (sample's peak frequency)/
(the local proton gyrofrequency) of the He‐band waves (∼0.11–0.16) under steady quiet conditions is lower than that (∼0.14–0.24) in previous studies. These results may be due to the fact that the plasmasphere expanded more frequently to the geosynchronous region under extremely quiet geomagnetic conditions in 2007–2008 than the periods selected in previous studies. The amplitude and frequency of He‐band EMIC waves for nonlinear wave growth are examined as changing cold plasma density at geosynchronous orbit. We confirm that the spectral properties of observed EMIC waves are in good agreement with the nonlinear theory.
Scaling the sandbox—Mechanical (dis) similarities of granular materials and brittle rock
Authors: Ritter Malte C. , Leever Karen , Rosenau Matthias , Oncken Onno 
Published: August 2016

AbstractAnalog sandbox experiments are an important tool to understand brittle tectonic deformation. To date, most experiments are interpreted kinematically only. With the advent of reliable, small‐scale force sensors, however, their dynamic evolution becomes available for analysis, offering new insights into the transient evolution of tectonic systems. Both rock and granular materials show an evolution of strain hardening and weakening during loading in the brittle‐plastic regime, but so far, this similarity has only been appreciated qualitatively. As strain weakening is a vital parameter controlling fault reactivation and lifetime, it requires proper scaling. We therefore measured and analyzed two common granular analog model materials (quartz sand and glass microbeads) using ring‐shear tests at a range of normal loads typical for analog experiments. We find two different modes of strain weakening as a function of normal load: Strain weakening at normal loads <1 kPa is due to partial loss of extrapolated cohesion, while at normal loads >1 kPa it is controlled by reduction of internal friction, which is consistent with previous measurements in this range. We show that this introduces a scale dependence into the scaling and restricts the possible use of the tested materials to crustal‐scale models with a length scaling factor of
. For these we quantitatively compare the model materials' transient strength evolution to that known from natural rock and the Earth's crust.
A hybrid method to estimate suspended particle sizes from satellite measurements over Bohai Sea and Yellow Sea
Authors: Sun Deyong , Qiu Zhongfeng , Hu Chuanmin , Wang Shengqiang , Wang Lin , Zheng Lufei , Peng Tian , He Yijun 
Published: August 2016

AbstractParticle‐size distribution (PSD), a measure of particle concentrations at different sizes, is of great importance to the understanding of many biogeochemical processes in coastal marine ecosystems. Here, a hybrid method, including analytical, semianalytical, and empirical steps, is developed to estimate PSD through the median diameter of suspended particles (
). Four cruise surveys were conducted to measure optical scattering properties, particle concentrations, spectral reflectance, and particle‐size distributions (obtained with a LISST instrument covering a size range of 2.5–500 μm) in coastal waters of Bohai Sea, Yellow Sea, and Jiangsu coastal region. Based on the Mie scattering theory,
is closely related to mass‐specific backscattering coefficient of suspended particles (
), and their relationship is calibrated through a power model (R2 = 0.796, n = 67, p < 0.001) for the
range of 23.5–379.8 μm. The model is shown to perform better than the previously used inverse‐proportion model. The retrieval of
is through a bio‐optical model that links remote sensing reflectance just beneath the surface to inherent optical properties, where a close empirical relationship is established between particulate backscattering and particle concentration. The hybrid method shows high degree of fitting (R2 = 0.875, n = 46, p < 0.001) between the measured and estimated
for the size range of 17.2–325.2 μm used in the model calibration, while validation using two independent data sets shows mean absolute percentage errors of 46.0% and 64.7%, respectively. Application of the hybrid method to MODIS (Moderate Resolution Imaging Spectroradiometer) data results in spatial distributions of
that are generally consistent with those from in situ observations, suggesting potential use of the method in studying particle dynamics through time series of remote sensing observations. However, its general applicability to other regions still requires further research.
The phenology of Arctic Ocean surface warming
Authors: Steele Michael , Dickinson Suzanne 
Published: August 2016

AbstractIn this work, we explore the seasonal relationships (i.e., the phenology) between sea ice retreat, sea surface temperature (SST), and atmospheric heat fluxes in the Pacific Sector of the Arctic Ocean, using satellite and reanalysis data. We find that where ice retreats early in most years, maximum summertime SSTs are usually warmer, relative to areas with later retreat. For any particular year, we find that anomalously early ice retreat generally leads to anomalously warm SSTs. However, this relationship is weak in the Chukchi Sea, where ocean advection plays a large role. It is also weak where retreat in a particular year happens earlier than usual, but still relatively late in the season, primarily because atmospheric heat fluxes are weak at that time. This result helps to explain the very different ocean warming responses found in two recent years with extreme ice retreat, 2007 and 2012. We also find that the timing of ice retreat impacts the date of maximum SST, owing to a change in the ocean surface buoyancy and momentum forcing that occurs in early August that we term the Late Summer Transition (LST). After the LST, enhanced mixing of the upper ocean leads to cooling of the ocean surface even while atmospheric heat fluxes are still weakly downward. Our results indicate that in the near‐term, earlier ice retreat is likely to cause enhanced ocean surface warming in much of the Arctic Ocean, although not where ice retreat still occurs late in the season.
Seasonal evolution of the Yellow Sea Cold Water Mass and its interactions with ambient hydrodynamic system
Authors: Li Jianchao , Li Guangxue , Xu Jishang , Dong Ping , Qiao Lulu , Liu Shidong , Sun Pingkuo , Fan Zhisong 
Published: August 2016

AbstractThe Yellow Sea Cold Water Mass (YSCWM) is an important component of the hydrodynamic system in the South Yellow Sea (SYS). However, its intricate interactions with the ambient flows over long time scales are not fully understood. This paper presents the analysis of the data set obtained from a seabed‐mounted Acoustic Doppler Current Profiler (ADCP) deployed for nearly 1 year in the western SYS. It allowed us to study the evolution of YSCWM, including the seasonal changes of tidal currents, near‐inertial oscillations (NIOs), and the wind‐driven currents due to typhoons and winter storms. Strong NIOs were found near the bottom of mixed layer and in the pycnocline with nearly opposite current directions, with maximum velocity of nearly 20 cm·s−1 in summer. The YSCWM can also inhibit the direct downward energy transport in the water column due to typhoons. Conversely, the hydrodynamic system also feeds back to influence the change of YSCWM. A large current shear (S) of 20 cm·s−1·m−1 is generated near the top of pycnocline. Generally, the intensity and depth of the pycnocline determine S's magnitude and vertical location, respectively. Based on the monthly averaged density profile data, the Richardson number and wavelet analysis, the NIOs are considered to be capable of inducing predominant shear instability around the pycnocline. However, the NIOs are not strong enough to influence the lower YSCWM. In addition, in autumn, each fortnightly spring tide corresponds with a bottom temperature increase of nearly 2°C, indicating that tidal currents are the leading hydrodynamic driving force to decline the YSCWM.
Evaporation and surface energy budget over the largest high‐altitude saline lake on the Qinghai‐Tibet Plateau
Authors: Li Xiao‐Yan , Ma Yu‐Jun , Huang Yong‐Mei , Hu Xia , Wu Xiu‐Chen , Wang Pei , Li Guang‐Yong , Zhang Si‐Yi , Wu Hua‐Wu , Jiang Zhi‐Yun , Cui Bu‐Li , Liu Lei 
Published: August 2016

AbstractInteractions between lakes and the atmosphere at high altitudes are still poorly understood due to difficulty in accessibility of direct measurements. This is particularly true for the Qinghai‐Tibet Plateau (QTP), where approximately 50% of the lakes in China are located. Continuous direct measurements of the water flux and surface energy budget were made over the largest high‐altitude saline lake in China, Qinghai Lake on the northeastern QTP, using the eddy covariance method from 11 May 2013 to 10 May 2015. Results indicated that annual evaporation of Qinghai Lake was 832.5 mm for 2013/2014 and 823.6 mm for 2014/2015, respectively. The surface energy budget and evaporation showed a strong seasonal pattern, with peaks in the latent and sensible heat flux observed in autumn and early winter. There was a 2–3 month delay between the maximum net radiation and maximum latent and sensible heat fluxes. Intraseasonal and seasonal variations in latent and sensible heat flux were strongly affected by different air masses. Westerly cold and dry air masses increased evaporation while southeast moist air mass suppressed evaporation, suggesting that the lakes might serve as an “air conditioner” to modify the temporal heat and water flux in the QTP.
Climate‐tectonic coupling: Variations in the mean, variations about the mean, and variations in mode
Authors: Lenardic A. , Jellinek A. M. , Foley B. , O'Neill C. , Moore W. B. 
Published: August 2016

AbstractInteractions among tectonics, volcanism, and surface weathering are critical to the long‐term climatic state of a terrestrial planet. Volcanism cycles greenhouse gasses into the atmosphere. Tectonics creates weatherable topography, and weathering reactions draw greenhouse gasses out of the atmosphere. Weathering depends on physical processes governed partly by surface temperature, which allows for the potential that climate‐tectonic coupling can buffer the surface conditions of a planet in a manner that allows liquid water to exist over extended timescales (a condition that allows a planet to be habitable by life as we know it). We discuss modeling efforts to explore the level to which climate‐tectonic coupling can or cannot regulate the surface temperature of a planet over geologic time. Thematically, we focus on how coupled climate‐tectonic systems respond to the following: (1) changes in the mean pace of tectonics and associated variations in mantle melting and volcanism, (2) large‐amplitude fluctuations about mean properties such as mantle temperature and surface plate velocities, and (3) changes in tectonic mode. We consider models that map the conditions under which plate tectonics can or cannot provide climate buffering as well as models that explore the potential that alternate tectonic modes can provide a level of climate buffering that allows liquid water to be present at a planet's surface over geological timescales. We also discuss the possibility that changes in the long‐term climate state of a planet can feedback into the coupled system and initiate changes in tectonic mode.
A process‐oriented evaluation of dust emission parameterizations in CESM: Simulation of a typical severe dust storm in East Asia
Authors: Wu Chenglai , Lin Zhaohui , He Juanxiong , Zhang Minghua , Liu Xiaohong , Zhang Renjian , Brown Hunter 
Published: August 2016

AbstractDust emissions in climate and earth system models are associated with large uncertainties. These models often use the source erodibility (S) to constrain dust emissions and also lack explicit representations of the impact of surface roughness elements (SREs) on the threshold friction velocity (u*t). This study presents a process‐oriented evaluation of dust emission parameterizations in the Community Earth System Model (CESM) by applying the model to simulate a severe dust storm during 19–22 March 2010 in East Asia. Through numerical experiments, we assess the applicability of S and investigate the impact of SREs on dust emissions by implementing the roughness correction factor (fλ) to u*t. Simulation results are compared against the surface synoptic observations and station observations of dust concentrations. We found that the model can capture the main dust emission regions and reproduce the temporal‐spatial evolution of surface dust concentrations in Mongolia and northern China. With a geomorphic S (Sg), the model tends to produce excessive dust emissions over the low‐lying basins. Moreover, the high‐resolution Sg performs worse with “point sources” of strong dust emissions than the low‐resolution one. With the inclusion of fλ, total dust emissions are reduced by 24–34%, and the model reduces the overestimation of surface dust concentrations and improves their temporal variations over the vegetated regions. These results suggest that Sg may not be necessary when meteorology and land surface state are well simulated by the model and that fλ provides an important constraint on dust emissions through SREs.
A new method to partition climate and catchment effect on the mean annual runoff based on the Budyko complementary relationship
Authors: Zhou Sha , Yu Bofu , Zhang Lu , Huang Yuefei , Pan Ming , Wang Guangqian 
Published: August 2016

AbstractEffect of climate change and catchment change on the long‐term water balance is of considerable interest at a range of spatial scales. The total differential of runoff within the Budyko framework, which has been widely used to attribute the change in runoff to the effect of climate and catchment changes, is not precise in which there is always some residual between the observed and estimated change in runoff. The objective of this study is to propose and evaluate a new partition method based on the Budyko complementary relationship for runoff. Algebraic identities have ensured that the change in runoff can be decomposed into two components precisely without any residuals using this complementary method. In addition, the complementary method allows estimation of the upper and lower bounds of the climate effect and catchment effect. The new method was compared with the total differential method and an extrapolation method for 15 catchments in Australia. Results show that the average range of the catchment effect using the complementary method was 6.7 mm for 14 of the 15 catchments, which is much smaller than that estimated with the total differential method (51.5 mm). The average of the upper and lower bounds was shown to be in good agreement with the effect of climate and catchment changes estimated using the extrapolation method (R2 = 0.98 for both). Correlation analysis indicates that the average of these bounds is the best estimate of the magnitude of the climate and catchment effect for the 15 catchments examined.
Pore‐scale modeling of vapor transport in partially saturated capillary tube with variable area using chemical potential
Authors: Addassi Mouadh , Schreyer Lynn , Johannesson Björn , Lin Hai 
Published: August 2016

AbstractHere we illustrate the usefulness of using the chemical potential as the primary unknown by modeling isothermal vapor transport through a partially saturated cylindrically symmetric capillary tube of variable cross‐sectional area using a single equation. There are no fitting parameters and the numerical solutions to the equation are compared with experimental results with excellent agreement. We demonstrate that isothermal vapor transport can be accurately modeled without modeling the details of the contact angle, microscale temperature fluctuations, or pressure fluctuations using a modification of the Fick‐Jacobs equation. We thus conclude that for a single, axisymmetric pore, the enhancement factor depends upon relative humidity boundary conditions at the liquid bridge interfaces, distance between liquid bridges, and bridge lengths.
Alpha‐synuclein RT‐QuIC in the CSF of patients with alpha‐synucleinopathies
Authors: Fairfoul Graham , McGuire Lynne I. , Pal Suvankar , Ironside James W. , Neumann Juliane , Christie Sharon , Joachim Catherine , Esiri Margaret , Evetts Samuel G. , Rolinski Michal , Baig Fahd , Ruffmann Claudio , Wade‐Martins Richard , Hu Michele T. M. , Parkkinen Laura , Green Alison J. E. 
Published: August 2016

AbstractWe have developed a novel real‐time quaking‐induced conversion RT‐QuIC‐based assay to detect alpha‐synuclein aggregation in brain and cerebrospinal fluid from dementia with Lewy bodies and Parkinson's disease patients. This assay can detect alpha‐synuclein aggregation in Dementia with Lewy bodies and Parkinson's disease cerebrospinal fluid with sensitivities of 92% and 95%, respectively, and with an overall specificity of 100% when compared to Alzheimer and control cerebrospinal fluid. Patients with neuropathologically confirmed tauopathies (progressive supranuclear palsy; corticobasal degeneration) gave negative results. These results suggest that RT‐QuiC analysis of cerebrospinal fluid is potentially useful for the early clinical assessment of patients with alpha‐synucleinopathies.
An Experimental Study on Mechanical Behavior of Nanographene/Epoxy Nanocomposites
Authors: Altan Mihrigül , Uysal Alper 
Published: August 2016

AbstractNanocomposites draw attention from many various fields and areas of usage increase with the improvement of their properties. For this purpose, nanographene particles have used to enhance the mechanical, thermal, and electrical properties. In the presented experimental study, nanocomposites were fabricated by reinforcing the epoxy matrix with nanographene particles at 0.5 and 1 wt%. The dispersion of nanofillers in epoxy matrix and the tensile properties of the nanocomposites were investigated. The tensile strength and stress at break increased with nanographene particles addition and well dispersion of nanofillers in epoxy matrix was achieved.