bluuebunny/crossref_metadata_2025_split huggingface dataset:
Variable Melt Production Rate of the Kerguelen HotSpot Due To Long‐Term Plume‐Ridge Interaction
Authors: Bredow Eva , Steinberger Bernhard 
Published: December 2017

AbstractFor at least 120 Myr, the Kerguelen plume has distributed enormous amounts of magmatic rocks over various igneous provinces between India, Australia, and Antarctica. Previous attempts to reconstruct the complex history of this plume have revealed several characteristics that are inconsistent with properties typically associated with plumes. To explore the geodynamic behavior of the Kerguelen hotspot, and in particular address these inconsistencies, we set up a regional viscous flow model with the mantle convection code ASPECT. Our model features complex time‐dependent boundary conditions in order to explicitly simulate the surrounding conditions of the Kerguelen plume. We show that a constant plume influx can result in a variable magma production rate if the plume interacts with nearby spreading ridges and that a dismembered plume, multiple plumes, or solitary waves in the plume conduit are not required to explain the fluctuating magma output and other unusual characteristics attributed to the Kerguelen hotspot.
Langmuir Circulation With Explicit Surface Waves From Moving‐Mesh Modeling
Authors: Wang P. , Özgökmen T. M. 
Published: December 2017

AbstractUsing a moving‐mesh, nonhydrostatic, spectral element model, we simulate Langmuir circulation with Navier‐Stokes equations under explicit, freely propagating surface waves. For comparison, Langmuir circulation is also simulated with Craik‐Leibovich (C‐L) equations. In both simulations, the Langmuir circulations are very similar, including temporal formation progresses and spatial structures; however, the strength of Langmuir circulation in the C‐L simulation is a bit weaker, which we suggest is due to the lack of Eulerian mean drift induced by fluid viscosity in the presence of explicit surface waves.
The Crossover Time as an Evaluation of Ocean Models Against Persistence
Authors: Phillipson L. M. , Toumi R. 
Published: December 2017

AbstractA new ocean evaluation metric, the crossover time, is defined as the time it takes for a numerical model to equal the performance of persistence. As an example, the average crossover time calculated using the Lagrangian separation distance (the distance between simulated trajectories and observed drifters) for the global MERCATOR ocean model analysis is found to be about 6 days. Conversely, the model forecast has an average crossover time longer than 6 days, suggesting limited skill in Lagrangian predictability by the current generation of global ocean models. The crossover time of the velocity error is less than 3 days, which is similar to the average decorrelation time of the observed drifters. The crossover time is a useful measure to quantify future ocean model improvements.
The Evolution and Structure of Extreme Optical Lightning Flashes
Authors: Peterson Michael , Rudlosky Scott , Deierling Wiebke 
Published: December 2017

AbstractThis study documents the composition, morphology, and motion of extreme optical lightning flashes observed by the Lightning Imaging Sensor (LIS). The furthest separation of LIS events (groups) in any flash is 135 km (89 km), the flash with the largest footprint had an illuminated area of 10,604 km2, and the most dendritic flash has 234 visible branches. The longest‐duration convective LIS flash lasted 28 s and is overgrouped and not physical. The longest‐duration convective‐to‐stratiform propagating flash lasted 7.4 s, while the longest‐duration entirely stratiform flash lasted 4.3 s. The longest series of nearly consecutive groups in time lasted 242 ms. The most radiant recorded LIS group (i.e., “superbolt”) is 735 times more radiant than the average group. Factors that impact these optical measures of flash morphology and evolution are discussed. While it is apparent that LIS can record the horizontal development of the lightning channel in some cases, radiative transfer within the cloud limits the flash extent and level of detail measured from orbit. These analyses nonetheless suggest that lightning imagers such as LIS and Geostationary Lightning Mapper can complement ground‐based lightning locating systems for studying physical lightning phenomena across large geospatial domains.
Positive or Negative? Urbanization‐Induced Variations in Diurnal Skin‐Surface Temperature Range Detected Using Satellite Data
Authors: Huang Fan , Zhan Wenfeng , Wang Zhihua , Wang Kaicun , Chen Jing M. , Liu Yongxue , Lai Jiameng , Ju Weimin 
Published: December 2017

AbstractDiurnal temperature range (DTR) is an important indicator for assessing the local climate change due to urbanization. Studies that focused on surface air temperature (SAT) have reported decreased DTRSAT in urban areas. However, this urbanization‐induced effect becomes more complex with regard to land skin‐surface temperature (LST), which is highly localized and extremely sensitive to land surface properties. We thus investigated the urban‐rural DTRLST difference (ΔDTRLST) over 354 cities across China using satellite‐retrieved LSTs within 2008−2013. Our major findings include the following: (1) urban areas experience increased (decreased) DTRLST compared with rural areas on the annual average for the majority of cities located in southern (northern) China; (2) the ΔDTRLST is mostly positive in warm months but negative in cold months. It generally becomes more positive from January to August and becomes more negative afterward; and (3) the ΔDTRLST is positively related to the daytime surface urban heat island intensity; it is yet negatively correlated with the urban‐rural difference in vegetation abundance. We consider these insights valuable for in‐depth understanding urban thermal environment and will likely help improve urban planning.
Environments of Long‐Lived Mesoscale Convective Systems Over the Central United States in Convection Permitting Climate Simulations
Authors: Yang Qing , Houze Robert A. , Leung L. Ruby , Feng Zhe 
Published: December 2017

AbstractContinental‐scale convection‐permitting simulations of the warm seasons of 2011 and 2012 using the Weather Research and Forecasting model reproduce realistic structure and frequency distribution of lifetime and event mean precipitation of mesoscale convective systems (MCSs) over the central United States. Analysis is performed to determine the environmental conditions conducive to generating long‐lived MCSs. The simulations show that MCSs systematically form over the central Great Plains ahead of a trough in the westerlies in combination with an enhanced low‐level moist jet from the Gulf of Mexico. These environmental properties at the time of storm initiation are most prominent for the MCSs that persist for the longest times. MCSs reaching lifetimes of 9 h or more occur closer to the approaching trough than shorter‐lived MCSs. These long‐lived MCSs exhibit the strongest feedback to the environment through diabatic heating in the trailing regions of the MCSs. The feedback strengthens the synoptic‐scale trough associated with the MCS by producing an anomaly circulation characterized by a divergent perturbation at high levels over the MCS and a midlevel cyclonic circulation perturbation near the trough line in association with the trailing portion of the MCS. The quasi‐balanced mesoscale vortex may help to maintain the MCS over a long period of time by feeding dry, cool air into the environment at the rear of the MCS region that enhances evaporative cooling and helps maintain the MCS.
Evaluation of an Improved Quasi‐stochastic Collection Model Through Precipitation Prediction Over North Central Mongolia
Authors: Lkhamjav Jambajamts , Jeon Ye‐Lim , Lee Hyunho , Baik Jong‐Jin , Seo Jaemyeong Mango 
Published: December 2017

AbstractOne of the key components of bin microphysics schemes is the quasi‐stochastic collection equation that describes the collection process of cloud particles. The normal quasi‐stochastic model, hereafter the NQS model, assumes that the time step is infinitesimally small, so that a cloud particle can collide with other cloud particle only once within the time step. However, since the time step is finite, a cloud particle can collide with other cloud particle more than one time within the time step. Hence, the improved quasi‐stochastic model that realizes this approach, hereafter the IQS model, is physically more reasonable. This study provides the evaluation of the IQS model against the NQS model in precipitation prediction. For this, a precipitation event observed over north central Mongolia on 21 August 2014 is simulated using the Weather Research and Forecasting model with a detailed bin microphysics scheme. The surface precipitation amount is larger in the IQS model than in the NQS model, particularly over the strong precipitation region. The IQS model increases the mass contents of small drops and large drops due to multiple collisions. The increased large drops contribute to the increase in surface precipitation amount. The increased small drops are transported upward, which eventually leads to an increase in snow mass content. Deposition and riming in the IQS model occur more actively, further increasing snow mass content. The increased snow mass content also contributes to the increase in surface precipitation amount through melting.
Investigating Dry Deposition of Ozone to Vegetation
Authors: Silva Sam J. , Heald Colette L. 
Published: December 2017

AbstractAtmospheric ozone loss through dry deposition to vegetation is a critically important process for both air quality and ecosystem health. The majority of atmospheric chemistry models calculate dry deposition using a resistance‐in‐series parameterization by Wesely (1989), which is dependent on many environmental variables and lookup table values. The uncertainties contained within this parameterization have not been fully explored, ultimately challenging our ability to understand global scale biosphere‐atmosphere interactions. In this work, we evaluate the GEOS‐Chem model simulation of ozone dry deposition using a globally distributed suite of observations. We find that simulated daytime deposition velocities generally reproduce the magnitude of observations to within a factor of 1.4. When correctly accounting for differences in land class between the observations and model, these biases improve, most substantially over the grasses and shrubs land class. These biases do not impact the global ozone burden substantially; however, they do lead to local absolute changes of up to 4 ppbv and relative changes of 15% in summer surface concentrations. We use MERRA meteorology from 1979 to 2008 to assess that the interannual variability in simulated annual mean ozone dry deposition due to model input meteorology is small (generally less than 5% over vegetated surfaces). Sensitivity experiments indicate that the simulation is most sensitive to the stomatal and ground surface resistances, as well as leaf area index. To improve ozone dry deposition models, more measurements are necessary over rainforests and various crop types, alongside constraints on individual depositional pathways and other in‐canopy ozone loss processes.
Linking Barbados Mineral Dust Aerosols to North African Sources Using Elemental Composition and Radiogenic Sr, Nd, and Pb Isotope Signatures
Authors: Bozlaker Ayse , Prospero Joseph M. , Price Jim , Chellam Shankararaman 
Published: December 2017

AbstractLarge quantities of African dust are carried across the Atlantic to the Caribbean Basin and southern United States where it plays an important role in the biogeochemistry of soils and waters and in air quality. Dusts' elemental and isotopic composition was comprehensively characterized in Barbados during the summers of 2013 and 2014, the season of maximum dust transport. Although total suspended insoluble particulate matter (TSIP) mass concentrations varied significantly daily and between the two summers, the abundances (μg element/g TSIP) of 50 elements during “high‐dust days” (HDD) were similar. Aerosols were regularly enriched in Na, Cu, Zn, As, Se, Mo, Cd, Sn, Sb, and W relative to the upper continental crust. Enrichment of these elements, many of which are anthropogenically emitted, was significantly reduced during HDD, attributed to mixing and dilution with desert dust over source regions. Generally, Ti/Al, Si/Al, Ca/Al, Ti/Fe, Si/Fe, and Ca/Fe ratios during HDD differed from their respective values in hypothesized North African source regions. Nd isotope composition was relatively invariant for “low‐dust days” (LDD) and HDD. In contrast, HDD‐aerosols were more radiogenic exhibiting higher 87Sr/86Sr, 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios compared to LDD. Generally, Barbados aerosols' composition ranged within narrow limits and was much more homogeneous than that of hypothesized African source soils. Our results suggest that summertime Barbados aerosols are dominated by a mixture of particles originating from sources in the Sahara‐Sahel regions. The Bodélé Depression, long suspected as a major source, appears to be an insignificant contributor of summertime western Atlantic dust.
On Effective Radiative Forcing of Partial Internally and Externally Mixed Aerosols and Their Effects on Global Climate
Authors: Zhou Chen , Zhang Hua , Zhao Shuyun , Li Jiangnan 
Published: December 2017

AbstractThe total effective radiative forcing (ERF) due to partial internally mixed (PIM) and externally mixed (EM) anthropogenic aerosols, as well as their climatic effects since the year of 1850, was evaluated and compared using the aerosol‐climate online coupled model of BCC_AGCM2.0_CUACE/Aero. The influences of internal mixing (IM) on aerosol hygroscopicity parameter, optical properties, and concentration were considered. Generally, IM could markedly weaken the negative ERF and cooling effects of anthropogenic aerosols. The global annual mean ERF of EM anthropogenic aerosols from 1850 to 2010 was −1.87 W m−2, of which the aerosol‐radiation interactive ERF (ERFari) and aerosol‐cloud interactive ERF (ERFaci) were −0.49 and −1.38 W m−2, respectively. The global annual mean ERF due to PIM anthropogenic aerosols from 1850 to 2010 was −1.23 W m−2, with ERFari and ERFaci of −0.23 and −1.01 W m−2, respectively. The global annual mean surface temperature and water evaporation and precipitation were reduced by 1.74 K and 0.14 mm d−1 for EM scheme and 1.28 K and 0.11 mm d−1 for PIM scheme, respectively. However, the relative humidity near the surface was slightly increased for both mixing cases. The Intertropical Convergence Zone was southwardly shifted for both EM and PIM cases but was less southwardly shifted in PIM scheme due to the less reduction in atmospheric temperature in the midlatitude and low latitude of the Northern Hemisphere.
No Consistent Evidence for Advancing or Delaying Trends in Spring Phenology on the Tibetan Plateau
Authors: Wang Xufeng , Xiao Jingfeng , Li Xin , Cheng Guodong , Ma Mingguo , Che Tao , Dai Liyun , Wang Shaoying , Wu Jinkui 
Published: December 2017

AbstractVegetation phenology is a sensitive indicator of climate change and has significant effects on the exchange of carbon, water, and energy between the terrestrial biosphere and the atmosphere. The Tibetan Plateau, the Earth's “third pole,” is a unique region for studying the long‐term trends in vegetation phenology in response to climate change because of the sensitivity of its alpine ecosystems to climate and its low‐level human disturbance. There has been a debate whether the trends in spring phenology over the Tibetan Plateau have been continuously advancing over the last two to three decades. In this study, we examine the trends in the start of growing season (SOS) for alpine meadow and steppe using the Global Inventory Modeling and Mapping Studies (GIMMS)3g normalized difference vegetation index (NDVI) data set (1982–2014), the GIMMS NDVI data set (1982–2006), the Moderate Resolution Imaging Spectroradiometer (MODIS) NDVI data set (2001–2014), the Satellite Pour l'Observation de la Terre Vegetation (SPOT‐VEG) NDVI data set (1999–2013), and the Sea‐viewing Wide Field‐of‐View Sensor (SeaWiFS) NDVI data set (1998–2007). Both logistic and polynomial fitting methods are used to retrieve the SOS dates from the NDVI data sets. Our results show that the trends in spring phenology over the Tibetan Plateau depend on both the NDVI data set used and the method for retrieving the SOS date. There are large discrepancies in the SOS trends among the different NDVI data sets and between the two different retrieval methods. There is no consistent evidence that spring phenology (“green‐up” dates) has been advancing or delaying over the Tibetan Plateau during the last two to three decades. Ground‐based budburst data also indicate no consistent trends in spring phenology. The responses of SOS to environmental factors (air temperature, precipitation, soil temperature, and snow depth) also vary among NDVI data sets and phenology retrieval methods. The increases in winter and spring temperature had offsetting effects on spring phenology.
Screening the second‐trimester fetal heart in women with an increased body mass index using three‐dimensional volume sweep
Authors: Wye Deborah , Woo Joyce , Mein Brendan , Brown Chris , Benzie Ronald 
Published: December 2017

AbstractPurposeTo determine the percentage of fetal cardiac anatomy as detailed in the International Society of Ultrasound in Obstetrics and Gynecology Practice Guidelines on sonographic screening examination of the fetal heart, which can be visualised in women with a body mass index (BMI) >30 kg/m2 using three‐dimensional (3D) volume sweeps.Methods3D volumes of the fetal heart were taken prospectively in 40 fetuses during routine second‐trimester fetal anatomy scan. Scans and 3D volume sweeps were performed by two experienced sonographers and two experienced raters interpreted the 3D data. 3D volume acquisitions and post‐processing analysis were performed according to the techniques described by Weissmann‐Brenner et al.ResultsThe two raters were able to detect an average of 12.9 and 14.1 of the 16 parameters in the 40 patients. Agreement between raters for the 16 parameters had an average of 80%. Five parameters (stomach, situs, heart occupies a third of thoracic area, majority of heart in the left chest and cardiac axis) were detected by both raters on all patients. The range of agreement was between 40% and 100%. The three‐vessel view and bifurcation had agreement <60%.ConclusionConsistent identification of all views of the fetal heart was not achieved using the simple method described in women with a BMI > 30 kg/m2.
Oxidation von Wasserinhaltsstoffen im Photoreaktor
Authors: Gaupp David Raphael , Oppenländer Thomas 
Published: December 2017

ZusammenfassungDie Reaktionskinetik des Abbaus von organischen Stoffen mit der UV/H2O2‐Oxidation kann mittels angefärbter Wässer anschaulich ermittelt und dargestellt werden. Die Entfärbungsgeschwindigkeit einer wässrigen Rhodamin B Lösung in Gegenwart von Wasserstoffperoxid unter UV‐Bestrahlung hängt jedoch anlagenspezifisch nicht nur von der eingebrachten Lampenleistung ab. Weiterhin sind der Volumenstrom, die RhB‐Konzentration und die H2O2‐Konzentration ausschlaggebend. Somit haben wir hier eine Möglichkeit aufgezeigt, Photoreaktoren mit farbigen wässrigen Lösungen für die UV‐Oxidation von Wasserinhaltsstoffen mittels Variation der Betriebsparameter zu optimieren.Diese Versuchsreihe kann mit unterschiedlichen, kommerziell erhältlichen Photoreaktoren einfach durchgeführt werden. Besonders eignen sich Mikrophotoreaktoren für schulische Zwecke, wie sie von Coyle und Oelgemöller [7] beschrieben werden. Es sind die Sicherheitshinweise beim Umgang mit UV‐Licht zu beachten. Auch solare AOPs, wie zum Beispiel die Titandioxid‐Photokatalyse, können mit dieser Methodik anschaulich demonstriert werden.
[Carboxyl‐11C]Labelling of Four High‐Affinity cPLA2α Inhibitors and Their Evaluation as Radioligands in Mice by Positron Emission Tomography
Authors: Fisher Martin J. , McMurray Lindsay , Lu Shuiyu , Morse Cheryl L. , Liow Jeih‐San , Zoghbi Sami S. , Kowalski Aneta , Tye George L. , Innis Robert B. , Aigbirhio Franklin I. , Pike Victor W. 
Published: December 2017

AbstractCytosolic phospholipase A2α (cPLA2α) may play a critical role in neuropsychiatric and neurodegenerative disorders associated with oxidative stress and neuroinflammation. An effective PET radioligand for imaging cPLA2α in living brain might prove useful for biomedical research, especially on neuroinflammation. We selected four high‐affinity (IC50 2.1–12 nm) indole‐5‐carboxylic acid‐based inhibitors of cPLA2α, namely 3‐isobutyryl‐1‐(2‐oxo‐3‐(4‐phenoxyphenoxy)propyl)‐1H‐indole‐5‐carboxylic acid (1); 3‐acetyl‐1‐(2‐oxo‐3‐(4‐(4‐(trifluoromethyl)phenoxy)phenoxy)propyl)‐1H‐indole‐5‐carboxylic acid (2); 3‐(3‐methyl‐1,2,4‐oxadiazol‐5‐yl)‐1‐(2‐oxo‐3‐(4‐phenoxyphenoxy)propyl)‐1H‐indole‐5‐carboxylic acid (3); and 3‐(3‐methyl‐1,2,4‐oxadiazol‐5‐yl)‐1‐(3‐(4‐octylphenoxy)‐2‐oxopropyl)‐1H‐indole‐5‐carboxylic acid (4), for labelling in carboxyl position with carbon‐11 (t1/2=20.4 min) to provide candidate PET radioligands for imaging brain cPLA2α. Compounds [11C]1–4 were obtained for intravenous injection in adequate overall yields (1.1–5.5 %) from cyclotron‐produced [11C]carbon dioxide and with moderate molar activities (70–141 GBq μmol−1) through the use of Pd0‐mediated [11C]carbon monoxide insertion on iodo precursors. Measured logD7.4 values were within a narrow moderate range (1.9–2.4). After intravenous injection of [11C]1–4 in mice, radioactivity uptakes in brain peaked at low values (≤0.8 SUV) and decreased by about 90 % over 15 min. Pretreatments of the mice with high doses of the corresponding non‐radioactive ligands did not alter brain time–activity curves. Brain uptakes of radioactivity after administration of [11C]1 to wild‐type and P‐gp/BCRP dual knock‐out mice were similar (peak 0.4 vs. 0.5 SUV), indicating that [11C]1 and others in this structural class, are not substrates for efflux transporters.
Herbivory and pollen limitation at the upper elevational range limit of two forest understory plants of eastern North America
Authors: Rivest Sébastien , Vellend Mark 
Published: December 2017

AbstractStudies of species' range limits focus most often on abiotic factors, although the strength of biotic interactions might also vary along environmental gradients and have strong demographic effects. For example, pollinator abundance might decrease at range limits due to harsh environmental conditions, and reduced plant density can reduce attractiveness to pollinators and increase or decrease herbivory. We tested for variation in the strength of pollen limitation and herbivory by ungulates along a gradient leading to the upper elevational range limits of Trillium erectum (Melanthiaceae) and Erythronium americanum (Liliaceae) in Mont Mégantic National Park, Québec, Canada. In T. erectum, pollen limitation was higher at the range limit, but seed set decreased only slightly with elevation and only in one of two years. In contrast, herbivory of T. erectum increased from <10% at low elevations to >60% at the upper elevational range limit. In E. americanum, we found no evidence of pollen limitation despite a significant decrease in seed set with elevation, and herbivory was low across the entire gradient. Overall, our results demonstrate the potential for relatively strong negative interactions (herbivory) and weak positive interactions (pollination) at plant range edges, although this was clearly species specific. To the extent that these interactions have important demographic consequences—highly likely for herbivory on Trillium, based on previous studies—such interactions might play a role in determining plant species' range limits along putatively climatic gradients.