bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation of the marine boundary layer cloud and CCN properties under coupled and decoupled conditions over the Azores
Authors: Dong Xiquan , Schwantes Adam C. , Xi Baike , Wu Peng
Published: June 2015

Six coupled and decoupled marine boundary layer (MBL) clouds were chosen from the 19 month Atmospheric Radiation Measurement Mobile Facility data set over the Azores. Thresholds of liquid water potential temperature difference ΔθL < 0.5 K (>0.5 K) and total water mixing ratio difference Δqt < 0.5 g/kg (>0.5 g/kg) below the cloud base were used for selecting the coupled (decoupled) cases. A schematic diagram was given to demonstrate the coupled and decoupled MBL vertical structures and how they associate with nondrizzle, virga, and rain drizzle events. Out of a total of 2676 5 min samples, 34.5% were classified as coupled and 65.5% as decoupled, 36.2% as nondrizzle and 63.8% as drizzle (47.7% as virga and 16.1% as rain), and 33.4% as daytime and 66.6% as nighttime. The decoupled cloud layer is deeper (0.406 km) than coupled cloud layer (0.304 km), and its liquid water path and cloud droplet effective radius (re) values (122.1 gm−2 and 13.0 µm) are higher than coupled ones (83.7 gm−2 and 10.4 µm). Conversely, decoupled stratocumuli have lower cloud droplet number concentration (Nd) and surface cloud condensation nucleus (CCN) concentration (NCCN) (74.5 cm−3 and 150.9 cm−3) than coupled stratocumuli (111.7 cm−3 and 216.4 cm−3). The linear regressions between re and Nd with NCCN have demonstrated that coupled re and Nd strongly depend on NCCN and have higher correlations (−0.56 and 0.59) with NCCN than decoupled results (−0.14 and 0.25). The MBL cloud properties under nondrizzle and virga drizzle conditions are similar to each other but significantly different to those of rain drizzle.
Top‐down estimate of methane emissions in California using a mesoscale inverse modeling technique: The South Coast Air Basin
Authors: Cui Yu Yan , Brioude Jerome , McKeen Stuart A. , Angevine Wayne M. , Kim Si‐Wan , Frost Gregory J. , Ahmadov Ravan , Peischl Jeff , Bousserez Nicolas , Liu Zhen , Ryerson Thomas B. , Wofsy Steve C. , Santoni Gregory W. , Kort Eric A. , Fischer Marc L. , Trainer Michael
Published: June 2015

Methane (CH4) is the primary component of natural gas and has a larger global warming potential than CO2. Recent top‐down studies based on observations showed CH4 emissions in California's South Coast Air Basin (SoCAB) were greater than those expected from population‐apportioned bottom‐up state inventories. In this study, we quantify CH4 emissions with an advanced mesoscale inverse modeling system at a resolution of 8 km × 8 km, using aircraft measurements in the SoCAB during the 2010 Nexus of Air Quality and Climate Change campaign to constrain the inversion. To simulate atmospheric transport, we use the FLEXible PARTicle‐Weather Research and Forecasting (FLEXPART‐WRF) Lagrangian particle dispersion model driven by three configurations of the Weather Research and Forecasting (WRF) mesoscale model. We determine surface fluxes of CH4 using a Bayesian least squares method in a four‐dimensional inversion. Simulated CH4 concentrations with the posterior emission inventory achieve much better correlations with the measurements (R2 = 0.7) than using the prior inventory (U.S. Environmental Protection Agency's National Emission Inventory 2005, R2 = 0.5). The emission estimates for CH4 in the posterior, 46.3 ± 9.2 Mg CH4/h, are consistent with published observation‐based estimates. Changes in the spatial distribution of CH4 emissions in the SoCAB between the prior and posterior inventories are discussed. Missing or underestimated emissions from dairies, the oil/gas system, and landfills in the SoCAB seem to explain the differences between the prior and posterior inventories. We estimate that dairies contributed 5.9 ± 1.7 Mg CH4/h and the two sectors of oil and gas industries (production and downstream) and landfills together contributed 39.6 ± 8.1 Mg CH4/h in the SoCAB.
An examination of convective moistening of the lower stratosphere using satellite data
Authors: Sun Ying , Huang Yi
Published: June 2015

In this paper, we use satellite data to test the hypothesis that deep convection moistens the lower stratosphere. Water vapor measurements from Earth Observing System‐Microwave Limb Sounder and Atmospheric Chemistry Experiment‐Fourier Transform Spectrometer over North America are binned according to the International Satellite Cloud Climatology Project deep convection indices. The results show that in the North American region (50–112°W, 10–50°N) the convection‐impacted samples are significantly moister than the nonimpact samples in the lowermost stratospheric layer right above the tropopause, and a drier tendency is also noticed right above this moistened layer. Trajectory modeling is used to aid the identification of deep convection‐impacted water vapor samples. However, we find that a substantial fraction of high‐concentration (>8 ppmv) samples at 100 hPa cannot be attributed to nearby deep convections.
What happens to soil organic carbon as coastal marsh ecosystems change in response to increasing salinity? An exploration using ramped pyrolysis
Authors: Williams Elizabeth K. , Rosenheim Brad E.
Published: June 2015

Coastal wetlands store vast amounts of organic carbon, globally, and are becoming increasingly vulnerable to the effects of anthropogenic sea level rise. To understand the effect of sea level rise on organic carbon fate and preservation in this global sink, it is necessary to characterize differences in the biogeochemical stability of coastal wetland soil organic carbon (SOC). Here we use ramped pyrolysis/oxidation decomposition characteristics as proxies for SOC stability to understand the fate of carbon storage in coastal wetlands comprising the Mississippi River deltaic plain, undergoing rapid rates of local sea level rise. Soils from three wetland types (fresh, brackish, and salt marshes) along a salinity gradient were subjected to ramped pyrolysis analysis to evaluate decomposition characteristics related to thermochemical stability of SOC. At equivalent soil depths, we observed that fresh marsh SOC was more stable than brackish and salt marsh SOC. Depth, isotopic, elemental, and chemical compositions, bulk density, and water content of SOC all exhibited different relationships with SOC stability across the marsh salinity gradient, indicative of different controls on SOC stability within each marsh type. The differences in stability imply stronger preservation potential of fresh marsh soil carbon, compared to that of salt and brackish marshes. Considering projected marsh ecosystem responses to sea level rise, these observed stability differences are important in planning and implementing coastal wetland carbon‐focused remediation and improving climate model feedbacks with the carbon cycle. Specifically, our results imply that ecosystem changes associated with sea level rise will initiate the accumulation of less stable carbon in coastal wetlands.
Lithospheric architecture beneath Hudson Bay
Authors: Porritt Robert W. , Miller Meghan S. , Darbyshire Fiona A.
Published: June 2015

Hudson Bay overlies some of the thickest Precambrian lithosphere on Earth, whose internal structures contain important clues to the earliest workings of plate formation. The terminal collision, the Trans‐Hudson Orogen, brought together the Western Churchill craton to the northwest and the Superior craton to the southeast. These two Archean cratons along with the Paleo‐Proterozoic Trans‐Hudson internides, form the core of the North American craton. We use S to P converted wave imaging and absolute shear velocity information from a joint inversion of P to S receiver functions, new ambient noise derived phase velocities, and teleseismic phase velocities to investigate this region and determine both the thickness of the lithosphere and the presence of internal discontinuities. The lithosphere under central Hudson Bay approaches ∼350 km thick but is thinner (∼200–250 km) around the periphery of the Bay. Furthermore, the amplitude of the LAB conversion from the S receiver functions is unusually large for a craton, suggesting a large thermal contrast across the LAB, which we interpret as direct evidence of the thermal insulation effect of continents on the asthenosphere. Within the lithosphere, midlithospheric discontinuities, significantly shallower than the base of the lithosphere, are often imaged, suggesting the mechanisms that form these layers are common. Lacking time‐history information, we infer that these discontinuities reflect reactivation of formation structures during deformation of the craton.
Radiative flux and forcing parameterization error in aerosol‐free clear skies
Authors: Pincus Robert , Mlawer Eli J. , Oreopoulos Lazaros , Ackerman Andrew S. , Baek Sunghye , Brath Manfred , Buehler Stefan A. , Cady‐Pereira Karen E. , Cole Jason N. S. , Dufresne Jean‐Louis , Kelley Maxwell , Li Jiangnan , Manners James , Paynter David J. , Roehrig Romain , Sekiguchi Miho , Schwarzkopf Daniel M.
Published: June 2015

This article reports on the accuracy in aerosol‐ and cloud‐free conditions of the radiation parameterizations used in climate models. Accuracy is assessed relative to observationally validated reference models for fluxes under present‐day conditions and forcing (flux changes) from quadrupled concentrations of carbon dioxide. Agreement among reference models is typically within 1 W/m2, while parameterized calculations are roughly half as accurate in the longwave and even less accurate, and more variable, in the shortwave. Absorption of shortwave radiation is underestimated by most parameterizations in the present day and has relatively large errors in forcing. Error in present‐day conditions is essentially unrelated to error in forcing calculations. Recent revisions to parameterizations have reduced error in most cases. A dependence on atmospheric conditions, including integrated water vapor, means that global estimates of parameterization error relevant for the radiative forcing of climate change will require much more ambitious calculations.
The annual cycle in ENSO growth rate as a cause of the spring predictability barrier
Authors: Levine Aaron F. Z. , McPhaden Michael J.
Published: June 2015

The spring predictability barrier increases the uncertainty in ENSO forecasts starting before and during the boreal spring. Recent work has shown that the annual cycle of ENSO growth rate is responsible for phase locking of peak ENSO development to the boreal winter, suggesting that this annual cycle may play a role in the spring predictability barrier. To test this hypothesis, the annual cycle of ENSO growth rate is added to a damped, noise‐driven conceptual recharge oscillator model. When the annual cycle of ENSO growth rate is included, a spring predictability barrier develops, whereas without it ENSO predictability is independent of the forecast start date. When state‐dependent noise is included in the simulations in addition to the annual cycle of the growth rate, the spring predictability barrier is enhanced and more realistic.
Why compensated cold‐core rings look stable
Authors: Sutyrin Georgi
Published: June 2015

In contrast to many real‐ocean rings and eddies, circular vortices in idealized two‐layer models tend to be highly unstable, unless their radius is made small or their baroclinicity is made artificially weak. The addition of a middle layer with uniform potential vorticity weakens vertical coupling between the upper and lower layers that enhances vortex stability and makes the vortex lifespan more realistic. It is demonstrated here that such a three‐layer vortex model in so‐called compensated state (without rotation in the deep layer) possesses smaller lower interface slope than the two‐layer model that reduces the potential vorticity gradient in the lower layer and provides less unstable configurations. Numerical simulations of an unstable cyclone with parameters typical for cold‐core ring Bob reveal strong deformations and pulsations of the vortex core in the two‐layer setup, while the ring becomes only slightly deformed and looks stable when the middle layer with uniform potential vorticity is added to be consistent with observations. Enhanced vortex stability in such three‐layer setup has important implications for further studies of real‐ocean eddies.
Flapping motions of the magnetotail current sheet excited by nonadiabatic ions
Authors: Wei X. H. , Cai C. L. , Cao J. B. , Rème H. , Dandouras I. , Parks G. K.
Published: June 2015

Observations by the Cluster spacecraft on 3 August 2004 are presented as an example of flapping motions of the magnetotail current sheet excited by nonadiabatic ions. It is found that the current sheet up‐down motions are exactly corresponding to alternating hemispherical asymmetries of the bouncing ion population. We show that those hemisphere‐asymmetric nonadiabatic ion populations are present in the magnetic field configuration with an effective finite guiding component due to the local current sheet inclination. These results demonstrate that the current sheet flapping motion is a self‐organized circulation process between the alternating hemispherical asymmetries of the nonadiabatic ion population inside the plasma sheet and the current sheet equilibrium itself.
Charge exchange in cometary coma: Discovery of H− ions in the solar wind close to comet 67P/Churyumov‐Gerasimenko
Authors: Burch J. L. , Cravens T. E. , Llera K. , Goldstein R. , Mokashi P. , Tzou C.‐Y. , Broiles T.
Published: June 2015

As Rosetta was orbiting comet 67P/Churyumov‐Gerasimenko, the Ion and Electron Sensor detected negative particles with angular distributions like those of the concurrently measured solar wind protons but with fluxes of only about 10% of the proton fluxes and energies of about 90% of the proton energies. Using well‐known cross sections and energy‐loss data, it is determined that the fluxes and energies of the negative particles are consistent with the production of H− ions in the solar wind by double charge exchange with molecules in the coma.
The effects of climate model similarity on probabilistic climate projections and the implications for local, risk‐based adaptation planning
Authors: Steinschneider Scott , McCrary Rachel , Mearns Linda O. , Brown Casey
Published: June 2015

Approaches for probability density function (pdf) development of future climate often assume that different climate models provide independent information, despite model similarities that stem from a common genealogy (models with shared code or developed at the same institution). Here we use an ensemble of projections from the Coupled Model Intercomparison Project Phase 5 to develop probabilistic climate information, with and without an accounting of intermodel correlations, for seven regions across the United States. We then use the pdfs to estimate midcentury climate‐related risks to a water utility in one of the regions. We show that the variance of climate changes is underestimated across all regions if model correlations are ignored, and in some cases, the mean change shifts as well. When coupled with impact models of the hydrology and infrastructure of a water utility, the underestimated likelihood of large climate changes significantly alters the quantification of risk for water shortages by midcentury.
Phytoplankton biomass cycles in the North Atlantic subpolar gyre: A similar mechanism for two different blooms in the Labrador Sea
Authors: Lacour Léo , Claustre Hervé , Prieur Louis , D'Ortenzio Fabrizio
Published: June 2015

An analysis of seasonal variations in climatological surface chlorophyll points to distinct biogeographical zones in the North Atlantic subpolar gyre. In particular, the Labrador Sea appears well delineated into two regions on either side of the 60°N parallel, with very different climatological phytoplankton biomass cycles. Indeed, north of 60°N, an early and short spring bloom occurs in late April, while south of 60°N, the bloom gradually develops 1 month later and significant biomass persists all summer long. Nevertheless, at climatological scale, the first‐order mechanism that controls the bloom is identical for both bioregions. The light‐mixing regime can explain the bloom onset in both bioregions. In the Labrador Sea, the blooms seem to rely on a mean community compensation irradiance threshold value of 2.5 mol photon m−2 d−1 over the mixed layer.
A new aircraft hurricane wind climatology and applications in assessing the predictive skill of tropical cyclone intensity using high‐resolution ensemble forecasts
Authors: Judt Falko , Chen Shuyi S.
Published: June 2015

Hurricane surface wind is a key measure of storm intensity. However, a climatology of hurricane winds is lacking to date, largely because hurricanes are relatively rare events and difficult to observe over the open ocean. Here we present a new hurricane wind climatology based on objective surface wind analyses, which are derived from Stepped Frequency Microwave Radiometer measurements acquired by NOAA WP‐3D and U.S. Air Force WC‐130J hurricane hunter aircraft. The wind data were collected during 72 aircraft reconnaissance missions into 21 western Atlantic hurricanes from 1998 to 2012. This climatology provides an opportunity to validate hurricane intensity forecasts beyond the simplistic maximum wind speed metric and allows evaluating the predictive skill of probabilistic hurricane intensity forecasts using high‐resolution model ensembles. An example of application is presented here using a 1.3 km grid spacing Weather Research and Forecasting model ensemble forecast of Hurricane Earl (2010).
Climate change intensification of horizontal water vapor transport in CMIP5
Authors: Lavers David A. , Ralph F. Martin , Waliser Duane E. , Gershunov Alexander , Dettinger Michael D.
Published: June 2015

Global warming of the Earth's atmosphere is hypothesized to lead to an intensification of the global water cycle. To determine associated hydrological changes, most previous research has used precipitation. This study, however, investigates projected changes to global atmospheric water vapor transport (integrated vapor transport (IVT)), the key link between water source and sink regions. Using 22 global circulation models from the Climate Model Intercomparison Project Phase 5, we evaluate, globally, the mean, standard deviation, and the 95th percentiles of IVT from the historical simulations (1979–2005) and two emissions scenarios (2073–2099). Considering the more extreme emissions, multimodel mean IVT increases by 30–40% in the North Pacific and North Atlantic storm tracks and in the equatorial Pacific Ocean trade winds. An acceleration of the high‐latitude IVT is also shown. Analysis of low‐altitude moisture and winds suggests that these changes are mainly due to higher atmospheric water vapor content.
Anomalously strong vertical magnetic fields from distant ELF/VLF sources
Authors: Silber Israel , Price Colin , Galanti Eli , Shuval Abraham
Published: June 2015

There are many sources of very low frequency (VLF—3–30 kHz) and extremely low frequency (ELF—3–3000 Hz) radiation in the Earth‐ionosphere waveguide (e.g., lightning and ELF/VLF communication transmitters). At distances of thousands of kilometers from these sources, the vertical component of the ELF/VLF AC magnetic fields is expected to be very weak and several orders of magnitude lower than the horizontal magnetic components. However, measurements in Israel show a relatively strong vertical magnetic component in both the ELF and VLF bands, at the same order of magnitude as the horizontal components. Our measurements suggest that the real Earth‐ionosphere waveguide might often be very different from the theoretical waveguide used in model calculations. In addition, our results imply that using only the horizontal components for direction finding or the absolute magnetic field strength may result in errors, since often a significant fraction of the magnetic field energy hides in the vertical component.
The impact of a hot sodium ion population on the growth of the Kelvin‐Helmholtz instability in Mercury's magnetotail
Authors: Gingell P. W. , Sundberg T. , Burgess D.
Published: June 2015

Observations of Mercury's local plasma environment by MErcury Surface, Space ENvironment, GEochemistry, and Ranging have revealed that the planet hosts a strongly asymmetric magnetosphere as a result of an off‐axis dipolar or quadrupolar internal field and significant finite Larmor radius effects at the boundary layer between magnetospheric and solar wind plasma environments. One important asymmetry appears in the growth and evolution of Kelvin‐Helmholtz (K‐H) waves at the dawn and dusk flanks of the magnetopause. Linear analysis and global hybrid simulations support a dusk‐dawn asymmetry in the growth rate caused by finite Larmor radius effects, and indeed, K‐H waves have been almost exclusively observed at the dusk magnetopause during northward interplanetary magnetic field. Observations of these K‐H waves at sodium gyroscales invite investigation into the impact of the hot planetary sodium ion population, itself distributed preferentially on the dusk flank, on the growth of the K‐H instability and associated plasma transport. We present local two‐dimensional hybrid simulations of the dusk and dawn boundary layers, with varying magnetospheric sodium ion number density, and examine the associated changes in the growth rates of the K‐H instability, K‐H wave spectra, and cross‐boundary particle transport. We show that gyroresonance between growing K‐H vortices and sodium ion gyration introduces a strong spectral peak at sodium gyroscales at the dusk magnetopause, that an increase in sodium ion number density increases dawn‐dusk asymmetry of K‐H growth rates, and that cross‐boundary particle transport decreases with sodium number density at the dawn flank.
Frictional properties of the active San Andreas Fault at SAFOD: Implications for fault strength and slip behavior
Authors: Carpenter B. M. , Saffer D. M. , Marone C.
Published: June 2015

We present results from a comprehensive laboratory study of the frictional strength and constitutive properties for all three active strands of the San Andreas Fault penetrated in the San Andreas Observatory at Depth (SAFOD). The SAFOD borehole penetrated the Southwest Deforming Zone (SDZ), the Central Deforming Zone (CDZ), both of which are actively creeping, and the Northeast Boundary Fault (NBF). Our results include measurements of the frictional properties of cuttings and core samples recovered at depths of ~2.7 km. We find that materials from the two actively creeping faults exhibit low frictional strengths (μ = ~0.1), velocity‐strengthening friction behavior, and near‐zero or negative rates of frictional healing. Our experimental data set shows that the center of the CDZ is the weakest section of the San Andreas Fault, with μ = ~0.10. Fault weakness is highly localized and likely caused by abundant magnesium‐rich clays. In contrast, serpentine from within the SDZ, and wall rock of both the SDZ and CDZ, exhibits velocity‐weakening friction behavior and positive healing rates, consistent with nearby repeating microearthquakes. Finally, we document higher friction coefficients (μ > 0.4) and complex rate‐dependent behavior for samples recovered across the NBF. In total, our data provide an integrated view of fault behavior for the three active fault strands encountered at SAFOD and offer a consistent explanation for observations of creep and microearthquakes along weak fault zones within a strong crust.
Regional characteristics of tropical expansion and the role of climate variability
Authors: Lucas Christopher , Nguyen Hanh
Published: June 2015

Radiosonde‐based tropical expansion rate estimates for six continental‐centered regions of the globe are discussed. New results from the Northern Hemisphere are presented, complementing previous Southern Hemisphere (SH) results using an identical methodology. Expansion rates are largest over Asia and Australia‐New Zealand (ANZ). Other regions show more modest rates of expansion, and there is no statistically significant expansion over North America. In the hemispheric average, expansion rates are slightly larger in the SH. This asymmetry, although not statistically significant, is consistent with ozone depletion acting as a codriver of tropical expansion since 1979. The picture of regional expansion here is different from that in other studies or that derived solely from reanalyses. The relationships between tropical expansion and modes of climate variability are explored using partial regression techniques. Interannually, a relationship is seen with the El Niño–Southern Oscillation (ENSO) across most of the globe. Regionally, the Pacific Decadal Oscillation (PDO) has a significant impact over Asia, while the Southern Annular Mode (SAM) affects expansion over ANZ. Considering the longer‐term changes in the climate variability indices since 1979, it suggests that the PDO may account for up to 50% of the observed tropical expansion over Asia, while SAM may account for 20–30% of the SH expansion, particularly over ANZ. Decadal changes in ENSO may account for a further 20–30% of the global and regional trends. Accounting for the effect of climate variability helps to reconcile the differences in observations and model‐based simulations of tropical expansion.
Evaluating the advective Brewer‐Dobson circulation in three reanalyses for the period 1979–2012
Authors: Abalos Marta , Legras Bernard , Ploeger Felix , Randel William J.
Published: June 2015

Most chemistry‐climate models show an intensification of the Brewer‐Dobson circulation (BDC) in the stratosphere associated with increasing greenhouse gas emissions and ozone depletion in the last decades, but this trend remains to be confirmed in observational data. In this work the evolution of the advective BDC for the period 1979–2012 is evaluated and compared in three modern reanalyses (ERA‐Interim, MERRA, and JRA‐55). Three different estimates of the BDC are computed for each reanalysis, one based on the definition of the residual circulation and two indirect estimates derived from momentum and thermodynamic balances. The comparison among the nine estimates shows substantial uncertainty in the mean magnitude (∼40%) but significant common variability. The tropical upwelling series show variability linked to the stratospheric quasi‐biennial oscillation and to El Niño–Southern Oscillation (ENSO) and also reflect extreme events such as major sudden stratospheric warmings and volcanic eruptions. The trend analysis suggests a strengthening of tropical upwelling of around 2–5%/decade throughout the layer 100–10 hPa. The global spatial structure of the BDC trends provides evidence of an overall acceleration of the circulation in both hemispheres, with qualitative agreement among the estimates. The global BDC trends are mainly linked to changes in the boreal winter season and can be tracked to long‐term increases in the resolved wave drag in both hemispheres.
Environmental controls on storm intensity and charge structure in multiple regions of the continental United States
Authors: Fuchs Brody R. , Rutledge Steven A. , Bruning Eric C. , Pierce Jeffrey R. , Kodros John K. , Lang Timothy J. , MacGorman Donald R. , Krehbiel Paul R. , Rison William
Published: June 2015

A database consisting of approximately 4000 storm observations has been objectively analyzed to determine environmental characteristics that produce high radar reflectivities above the freezing level, large total lightning flash rates on the order of 10 flashes per minute, and anomalous vertical charge structures (most notably, dominant midlevel positive charge). The storm database is drawn from four regions of the United States featuring distinct environments, each with coinciding Lightning Mapping Array (LMA) network data. LMAs are able to infer total lightning flash rates using flash clustering algorithms, such as the one implemented in this study. Results show that anomalous charge structures inferred from LMA data, significant lightning flash rates, and increased radar reflectivities above the freezing level tend to be associated with environments that have high cloud base heights (approximately 3 km above ground level) and large atmospheric instability, quantified by normalized convective available potential energy (NCAPE) near 0.2 m s−2. Additionally, we infer that aerosols may affect storm intensity. Maximum flash rates were observed in storms with attributed aerosol concentrations near 1000 cm−3, while total flash rates decrease when aerosol concentrations exceed 1500 cm−3, consistent with previous studies. However, this effect is more pronounced in regions where the NCAPE and cloud base height are low. The dearth of storms with estimated aerosol concentrations less than 700 cm−3 (approximately 1% of total sample) does not provide a complete depiction of aerosol invigoration.
Reply to comment by R. Philipona on “A new absolute reference for atmospheric longwave irradiance measurements with traceability to SI units”
Authors: Gröbner Julian , Reda Ibrahim , Wacker Stefan , Nyeki Stephan , Behrens Klaus , Gorman J.
Published: June 2015

Key Points

Atmospheric longwave irradiance is currently not metrologically traceable

Traceability requires formal comparisons in the framwork of the CIPM MRA

A task team on Radiation has been created by the WMO to address these issues
Combining satellite precipitation and long‐term ground observations for hydrological monitoring in China
Authors: Zhang Xuejun , Tang Qiuhong
Published: June 2015

Satellite real‐time precipitation enables hydrological monitoring in China where the near‐real‐time ground observations are not readily available. However, the inconsistency between the real‐time satellite precipitation and gauge‐based retrospective data may introduce large systematic bias in near‐real‐time hydrological monitoring. Here we attempted to integrate the Tropical Rainfall Measuring Mission (TRMM) real‐time precipitation (3B42RTV7) into a 62 year gauge‐based retrospective product, the IGSNRR (Institute of Geographical Sciences and Natural Resources Research) dataset through matching their cumulative probability functions toward a near‐real‐time hydrological monitoring consistent with the long‐term retrospective simulations. A nearly 11 year period from March 2000 to December 2010 was taken as the training period to establish the satellite‐gauge precipitation relationship, which was employed in the period of 2011–2013 to evaluate the performance of the adjustment. The results show that the adjusted 3B42RTV7 matches well with IGSNRR precipitation, while the unadjusted data tend to overestimate precipitation. Forced by the adjusted 3B42RTV7, the Variable Infiltration Capacity model can reproduce the IGSNRR‐derived hydrographs and high/low flows better than the model forced by the unadjusted data. The percentiles of the adjusted hydrological estimates in the 62 year estimates from IGSNRR are used for near‐real‐time assessment of hydrological extremes. The hydrological monitoring assisted by the adjusted satellite precipitation, which enables the employment of the long‐term ground observations, is able to capture more detailed drought information than that before adjustment. Our experiment suggests that the satellite real‐time precipitation, after adjustment, can generate the current hydrological conditions which can be directly compared with the long‐term climatology, and thus facilitates near‐real‐time diagnosis and detection of hydrological extremes.
Reactivity continuum modeling of leaf, root, and wood decomposition across biomes
Authors: Koehler Birgit , Tranvik Lars J.
Published: June 2015

Large carbon dioxide amounts are released to the atmosphere during organic matter decomposition. Yet the large‐scale and long‐term regulation of this critical process in global carbon cycling by litter chemistry and climate remains poorly understood. We used reactivity continuum (RC) modeling to analyze the decadal data set of the “Long‐term Intersite Decomposition Experiment,” in which fine litter and wood decomposition was studied in eight biome types (224 time series). In 32 and 46% of all sites the litter content of the acid‐unhydrolyzable residue (AUR, formerly referred to as lignin) and the AUR/nitrogen ratio, respectively, retarded initial decomposition rates. This initial rate‐retarding effect generally disappeared within the first year of decomposition, and rate‐stimulating effects of nutrients and a rate‐retarding effect of the carbon/nitrogen ratio became more prevalent. For needles and leaves/grasses, the influence of climate on decomposition decreased over time. For fine roots, the climatic influence was initially smaller but increased toward later‐stage decomposition. The climate decomposition index was the strongest climatic predictor of decomposition. The similar variability in initial decomposition rates across litter categories as across biome types suggested that future changes in decomposition may be dominated by warming‐induced changes in plant community composition. In general, the RC model parameters successfully predicted independent decomposition data for the different litter‐biome combinations (196 time series). We argue that parameterization of large‐scale decomposition models with RC model parameters, as opposed to the currently common discrete multiexponential models, could significantly improve their mechanistic foundation and predictive accuracy across climate zones and litter categories.
Full‐wave model and numerical study of electromagnetic plane wave scattering by multilayered, fiber‐based periodic composites
Authors: Li C. Y. , Lesselier D. , Zhong Y.
Published: June 2015

The present work aims at building up a full‐wave computational model of electromagnetic nondestructive testing of composite materials produced by stacking up dielectric slabs one over the other. In each such dielectric slab, a periodic array of infinite cylindrical fibers is embedded. Electromagnetic scattering of such a multilayered, fiber‐based periodic composite is investigated here for an obliquely incident plane wave, the plane of incidence of which differs from the plane orthogonal to the fibers' axes. Full‐wave field representations are given first by multipole and plane wave expansions. Mode matching at boundaries between layers then yields the propagating matrices, which are applied to connect reflection and transmission coefficients of the longitudinal field components. Power reflection and transmission coefficients are obtained from time‐averaged Poynting vectors. Numerical experiments with comparisons with known results illustrate the accuracy of the model proposed.
Pracademia: The Future of the Lifelong Learner
Authors: Wilson M. D.
Published: June 2015

M. D. Wilson bridges the practical and the academic with the “pracademic,” his answer to engaging students in the learning process.
Distraction of Counting by the Meaning of Background Speech: Are Spatial Memory Demands a Prerequisite?
Authors: Ljung Robert , Marsh John E. , Sörqvist Patrik
Published: June 2015

This paper reexamines the effects of background speech on counting. Previous studies have shown that background sound disrupts counting in comparison with silence, but the magnitude of disruption is no larger for spoken numbers compared with that for non‐number speech (there is no effect of the meaning of background speech). The typical task used previously has been to count the number of sequentially presented visual events. We replicated the general finding in Experiment 1—that there is no effect of the meaning of background speech—in the context of the classic sequence counting task. In Experiment 2, the task was changed by having to‐be‐counted dots presented simultaneously and randomly across the visual field. Here, an effect attributable to the meaning of background speech emerged. Background speech that is similar in meaning to the focal task process contributes to the magnitude of disruption, but apparently only when spatial memory processes are a task prerequisite. Copyright © 2015 John Wiley & Sons, Ltd.
Formation of Cuboidal Co3AlC Precipitates in Carbon‐Containing Co–Al–W‐Based Superalloys
Authors: Freund Lisa Patricia , Bauer Alexander , Benker Lisa , Neumeier Steffen , Göken Mathias
Published: June 2015

The influence of Carbon addition on a ternary Co–Al–W alloy is investigated especially regarding phase stability and partitioning behavior of alloying elements. During casting and subsequent cooling, C‐additon leads to the formation of an interdendritic carbide network and to the homogeneous precipitation of cuboidal E21 phase, Co3AlC, in the W‐rich Co matrix. The solvus temperature of this phase is found to be about 1200 °C, which is significantly higher than the solvus temperature of the ternary L12 phase Co3(Al,W). In the course of solution heat treatment, the Co3AlC precipitates are dissolved and the carbides change in morphology and chemical composition. Further annealing leads to the precipitation of small cuboidal precipitates of L12 phase, Co3(Al,W), and to a discontinuous precipitation of further phases.
On the Thermodynamics and Kinetics of TCP Phase Precipitation in Re‐ and Ru‐ Containing Ni‐base Superalloys
Authors: Matuszewski Kamil , Müller Alexander , Ritter Nils , Rettig Ralf , Kurzydłowski Krzysztof J. , Singer Robert F.
Published: June 2015

Three experimental Ni‐base superalloys of the second, third and fourth generation are studied in this work to clarify the effect of Re and Ru on the precipitation of TCP phases. Thermodynamic calculations using the CALPHAD method are performed based on the local chemical composition obtained with the use of electron probe microanalysis. The effects of microsegregation and γ′‐precipitation are taken into account. The results, complemented with scanning electron microscopy observations, show that Re increases, while Ru decreases the inclination of the material to precipitate TCP phases. The effect of both elements is assigned to thermodynamic rather than kinetic reasons. The CALPHAD‐calculations do predict the effect of Re on the TCP phase formation in the investigated alloys correctly, but not the effect of Ru.
Low‐Temperature Transport in Crystalline Ge1Sb2Te4
Authors: Volker Hanno , Jost Peter , Wuttig Matthias
Published: June 2015

Disorder and its reduction upon annealing play a crucial role in understanding the electrical transport in the crystalline phase‐change material Ge1Sb2Te4. Previous studies focus either on the impact of disorder at moderate temperatures or on the low‐temperature properties of crystalline films with a low degree of disorder. The present investigation describes and discusses the impact of pronounced disorder on charge transport at low temperatures. The present data reveal the existence of a metal‐to‐insulator transition (MIT), where upon increasing order the zero‐temperature limit of conductivity changes from zero (insulator) to nonzero values (metal). The position of the MIT is determined with respect to the control parameter, i.e., the disorder, which is modified through the annealing conditions. Disorder is shown to localize carriers for an exceptionally large density of states. In the most disordered films, variable range hopping is observed, enabling the determination of the localization length. At the lowest temperatures studied, deviations from Mott variable range hopping are observed, which can be explained by a transition to Efros–Shklovskii hopping due to the presence of a soft Coulomb gap.
A Surface Tailoring Method of Ultrathin Polymer Gate Dielectrics for Organic Transistors: Improved Device Performance and the Thermal Stability Thereof
Authors: Seong Hyejeong , Baek Jieung , Pak Kwanyong , Im Sung Gap
Published: June 2015

Tailoring the surface of the dielectric layer is of critical importance to form a good interface with the following channel layer for organic thin film transistors (OTFTs). Here, a simple surface treatment method is applied onto an ultrathin (<15 nm) organosilicon‐based dielectric layer via the initiated chemical vapor deposition (iCVD) to make it compatible with organic semiconductors without degrading its insulating property. A molecular‐thin oxide capping layer is formed on a 15 nm thick poly(1,3,5‐trimetyl‐1,3,5‐trivinyl cyclotrisiloxane) (pV3D3) by a brief oxygen plasma treatment. The capping layer greatly enhances the thermal stability of the dielectrics, without degrading the original mechanical flexibility and insulating performance of the dielectrics. Moreover, the surface silanol functionalities formed by the plasma treatment can also be utilized for the surface modification with silane compounds. The surface‐modified dielectrics are applied to fabricate low‐voltage operating (<5 V) pentacene‐based OTFTs. The highest field‐effect mobility of the device with the surface‐treated 15 nm thick pV3D3 is 0.59 cm2 V−1 s−1, which is improved up to two times compared to the TFT with the pristine pV3D3. It is believed that the simple surface treatment method can widely extend the applicability of the highly robust, ultrathin, and flexible pV3D3 gate dielectrics to design the surface of the dielectrics to match well various kinds of organic semiconductors.
Surface Chemistry of Vitamin: Pyridoxal 5′‐Phosphate (Vitamin B6) as a Multifunctional Compound for Surface Functionalization
Authors: Lee Jung Seung , Kim Kyuri , Lee Kihong , Park Joseph P. , Yang Kisuk , Cho Seung‐Woo , Lee Haeshin
Published: June 2015

Vitamins are non‐toxic compounds that perform a variety of biological functions and also available in a large quantity. Other than the usage as food supplements, few attempts have been made to use them as functional materials. In this study, we report that vitamin B6, pyridoxal 5′‐phosphate (PLP), is a multi‐functional molecule for oxide surface chemistry. PLP‐immobilized surfaces exhibit superhydrophilicity and even hemophilicity, enhancing proliferation, migration, and differentiation of mammalian cells. Unlike existing molecules used so far in surface modification, PLP has an intrinsic chemical reactivity toward biomacromolecules due to the presence of the aldehyde group. In fact, RGD peptide is covalently tethered onto PLP surfaces directly in one step without any chemical activation. Furthermore, PLP‐functionalized implant device showed rapid bone healing. As vitamin B6 is a FDA approved molecule for human usage, the surface chemistry of vitamin B6 potentially allows a fast route for surface functionalized medical devices into clinic.
3D Printing of Scaffolds for Tissue Regeneration Applications
Authors: Do Anh‐Vu , Khorsand Behnoush , Geary Sean M. , Salem Aliasger K.
Published: June 2015

The current need for organ and tissue replacement, repair, and regeneration for patients is continually growing such that supply is not meeting demand primarily due to a paucity of donors as well as biocompatibility issues leading to immune rejection of the transplant. In order to overcome these drawbacks, scientists have investigated the use of scaffolds as an alternative to transplantation. These scaffolds are designed to mimic the extracellular matrix (ECM) by providing structural support as well as promoting attachment, proliferation, and differentiation with the ultimate goal of yielding functional tissues or organs. Initial attempts at developing scaffolds were problematic and subsequently inspired an interest in 3D printing as a mode for generating scaffolds. Utilizing three‐dimensional printing (3DP) technologies, ECM‐like scaffolds can be produced with a high degree of complexity, where fine details can be included at a micrometer level. In this Review, the criteria for printing viable and functional scaffolds, scaffolding materials, and 3DP technologies used to print scaffolds for tissue engineering are discussed. Creating biofunctional scaffolds could potentially help to meet the demand by patients for tissues and organs without having to wait or rely on donors for transplantation.
Exceptional Flame Resistance and Gas Barrier with Thick Multilayer Nanobrick Wall Thin Films
Authors: Guin Tyler , Krecker Michelle , Milhorn Aaron , Hagen David A. , Stevens Bart , Grunlan Jaime C.
Published: June 2015

Layer‐by‐layer (LbL) assembly is a powerful and versatile technique to deposit functional thin films, but often requires a large number of deposition steps to achieve a film thick enough to provide a desired property. By incorporating amine salts into the cationic polyelectrolyte and its associated rinse, LbL clay‐containing nanocomposite films can achieve much greater thickness (>1 μm) with relatively few deposition cycles (≤6 bilayers). Amine salts interact with nanoclays, causing nanoplatelets to deposit in stacks rather than as individual platelets. This technique appears to be universal, exhibiting thick growth with multiple types of nanoclay, including montmorillonite and vermiculite (VMT), and a variety of amine salts (e.g., hexylamine and diethanolamine). The characteristic order found in LbL‐assembled films is maintained despite the incredible thickness. Films assembled in this manner achieve oxygen transmission rates below 0.009 cc m−2d−1atm−1with just 6 bilayers (BLs) of chitosan/VMT deposited. These thick clay‐based thin films also impart exceptional flame resistance. A 2‐BL film renders a 3.2 mm polystyrene plate self‐extinguishing, while an 8‐BL film (3.9 μm thick) prevents ignition entirely. This ability to generate much thicker clay‐based multilayers with amine salts opens up tremendous potential for these nanocoatings in real world applications.
Intercalation and Push‐Out Process with Spinel‐to‐Rocksalt Transition on Mg Insertion into Spinel Oxides in Magnesium Batteries
Authors: Okamoto Shinya , Ichitsubo Tetsu , Kawaguchi Tomoya , Kumagai Yu , Oba Fumiyasu , Yagi Shunsuke , Shimokawa Kohei , Goto Natsumi , Doi Takayuki , Matsubara Eiichiro
Published: June 2015

On the basis of the similarity between spinel and rocksalt structures, it is shown that some spinel oxides (e.g., MgCo2O4, etc) can be cathode materials for Mg rechargeable batteries around 150 °C. The Mg insertion into spinel lattices occurs via “intercalation and push‐out” process to form a rocksalt phase in the spinel mother phase. For example, by utilizing the valence change from Co(III) to Co(II) in MgCo2O4, Mg insertion occurs at a considerably high potential of about 2.9 V vs. Mg2+/Mg, and similarly it occurs around 2.3 V vs. Mg2+/Mg with the valence change from Mn(III) to Mn(II) in MgMn2O4, being comparable to the ab initio calculation. The feasibility of Mg insertion would depend on the phase stability of the counterpart rocksalt XO of MgO in Mg2X2O4 or MgX3O4 (X = Co, Fe, Mn, and Cr). In addition, the normal spinel MgMn2O4 and MgCr2O4 can be demagnesiated to some extent owing to the robust host structure of Mg1−xX2O4, where the Mg extraction/insertion potentials for MgMn2O4 and MgCr2O4 are both about 3.4 V vs. Mg2+/Mg. Especially, the former “intercalation and push‐out” process would provide a safe and stable design of cathode materials for polyvalent cations.