bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rising methane emissions from northern wetlands associated with sea ice decline
Authors: Parmentier Frans‐Jan W. , Zhang Wenxin , Mi Yanjiao , Zhu Xudong , van Huissteden Jacobus , Hayes Daniel J. , Zhuang Qianlai , Christensen Torben R. , McGuire A. David 
Published: July 2015

AbstractThe Arctic is rapidly transitioning toward a seasonal sea ice‐free state, perhaps one of the most apparent examples of climate change in the world. This dramatic change has numerous consequences, including a large increase in air temperatures, which in turn may affect terrestrial methane emissions. Nonetheless, terrestrial and marine environments are seldom jointly analyzed. By comparing satellite observations of Arctic sea ice concentrations to methane emissions simulated by three process‐based biogeochemical models, this study shows that rising wetland methane emissions are associated with sea ice retreat. Our analyses indicate that simulated high‐latitude emissions for 2005–2010 were, on average, 1.7 Tg CH4 yr−1 higher compared to 1981–1990 due to a sea ice‐induced, autumn‐focused, warming. Since these results suggest a continued rise in methane emissions with future sea ice decline, observation programs need to include measurements during the autumn to further investigate the impact of this spatial connection on terrestrial methane emissions.
Probability density functions for the variable solar wind near the solar cycle minimum
Authors: Vörös Z. , Leitner M. , Narita Y. , Consolini G. , Kovács P. , Tóth A. , Lichtenberger J. 
Published: July 2015

AbstractUnconditional and conditional statistics are used for studying the histograms of magnetic field multiscale fluctuations in the solar wind near the solar cycle minimum in 2008. The unconditional statistics involves the magnetic data during the whole year in 2008. The conditional statistics involves the magnetic field time series split into concatenated subsets of data according to a threshold in dynamic pressure. The threshold separates fast‐stream leading edge compressional and trailing edge uncompressional fluctuations. The histograms obtained from these data sets are associated with both multiscale (B) and small‐scale (δB) magnetic fluctuations, the latter corresponding to time‐delayed differences. It is shown here that, by keeping flexibility but avoiding the unnecessary redundancy in modeling, the histograms can be effectively described by a limited set of theoretical probability distribution functions (PDFs), such as the normal, lognormal, kappa, and log‐kappa functions. In a statistical sense the model PDFs correspond to additive and multiplicative processes exhibiting correlations. It is demonstrated here that the skewed small‐scale histograms inherent in turbulent cascades are better described by the skewed log‐kappa than by the symmetric kappa model. Nevertheless, the observed skewness is rather small, resulting in potential difficulties of estimation of the third‐order moments. This paper also investigates the dependence of the statistical convergence of PDF model parameters, goodness of fit, and skewness on the data sample size. It is shown that the minimum lengths of data intervals required for the robust estimation of parameters is scale, process, and model dependent.
The effect of changing solar wind conditions on the inner magnetosphere and ring current: A model data comparison
Authors: Patra S. , Spencer E. 
Published: July 2015

AbstractWe investigate the rate at which the open drift paths in the near‐Earth magnetosphere convert to closed paths during events with a sudden northward turning of the interplanetary magnetic field (IMF Bz) after the peak of a geomagnetic storm. The geomagnetic storm on 17 August 2001 with an abrupt turning of the IMF Bz after the peak in SYM‐H index is chosen in this study. The Block‐Adaptive‐Tree Solar‐Wind Roe‐Type Upwind Scheme model along with the Fok Ring Current (FRC) model available at Community Coordinated Modeling Center is used to model this event. The unique movie maps of the worldwide magnetometer stations are used to compare with the numerical results. The results indicate that ground magnetic disturbance remains asymmetric for some time after the start of the recovery phase even for a storm with abrupt northward turning of the IMF Bz. FRC simulation results suggest that the flow‐out losses decrease under weakened magnetospheric convection but at a rate slower than the change in IMF Bz. These results indicate that the flow‐out losses rapidly become smaller as the IMF Bz turns northward during the early recovery phase of a storm and the contribution of the tail current to the SYM‐H index is important.
Formation of polar ionospheric tongue of ionization during minor geomagnetic disturbed conditions
Authors: Liu Jing , Nakamura Takuji , Liu Libo , Wang Wenbin , Balan Nanan , Nishiyama Takanori , Hairston Marc R. , Thomas E. G. 
Published: July 2015

AbstractPrevious investigations of ionospheric storm‐enhanced density (SED) and tongue of ionization (TOI) focused mostly on the behavior of TOI during intense geomagnetic storms. Little attention has been paid to the spatial and temporal variations of TOI during weak to moderate geomagnetic disturbed conditions. In this paper we investigate the source and development of TOI during a moderate geomagnetic storm on 14 October 2012. Multi‐instrumental observations including GPS total electron content (TEC), Defense Meteorological Satellite Program (DMSP) in situ measured total ion concentration and ion drift velocity, SuperDARN measured polar ion convection patterns, and electron density profiles from the Poker Flat Incoherent Scatter Radar (PFISR) have been utilized in the current analysis. GPS TEC maps show salient TOI structures persisting for about 5 h over high latitudes of North America on 14 October 2012 in the later recovery phase of the storm when the magnitudes of IMF By and Bz were less than 5 nT. The PFISR electron density profiles indicate that the extra ionization for TEC enhancements mainly occurred in the topside ionosphere with no obvious changes in the bottomside ionosphere and vertical plasma drifts. Additionally, there were no signatures of penetration electric fields in the equatorial electrojet data and upward ion drifts at high latitudes. At the same time, strong subauroral polarization streams with ion drift speeds exceeding 2.5 km/s carried sunward fluxes and migrated toward lower latitudes for about 5° based on the DMSP cross‐track drift measurements. Based on those measurements, we postulate that the combined effects of initial build‐up of ionization at midlatitudes through daytime production of ionization and equatorward (or less poleward than normal daytime) neutral wind reducing downward diffusion along the inclined filed lines, and an expanded polar ion convection pattern and its associated horizontal plasma transport are important in the formation of the TOI.
Fringe field dynamics over equatorial and low‐latitude ionosphere: A three‐dimensional perspective
Authors: Kherani E. A. , Patra A. K. 
Published: July 2015

AbstractThis paper presents a three‐dimensional simulation of the collisional interchange instability generating equatorial plasma bubble (EPB) in the evening ionospheric F region and associated fringe field (FF) in the valley‐upper‐E (VE) region. This simulation is primarily intended to address hitherto unexplained radar observations of ascending irregularity structures only in the vicinity of the magnetic equator in association with the EPB phenomenon. Novel results of the present simulation are the following: (1) EPB‐associated FF penetrating into the E region is found to be confined to a latitude belt of ±5∘, (2) ascending irregularity structures from the E region is formed only when perturbation in plasma parameters similar to those responsible for forming EPB are present in the VE region, and (3) perturbation in the VE region provide conditions for the formation of ascending irregularity structures on the eastern wall of the plasma bubble. These results are in excellent agreement with radar observations and also account for the presence of metallic ions in the EPB at and above the F region peak.
The impacts of mantle phase transitions and the iron spin crossover in ferropericlase on convective mixing—is the evidence for compositional convection definitive? New results from a Yin‐Yang overset grid‐based control volume model
Authors: Shahnas M. H. , Peltier W. R. 
Published: July 2015

AbstractHigh‐resolution seismic tomographic images from several subduction zones provide evidence for the inhibition of the downwelling of subducting slabs at the level of the 660 km depth seismic discontinuity. Furthermore, the inference of old (~140 Myr) sinking slabs below fossil subduction zones in the lower mantle has yet to be explained. We employ a control volume methodology to develop a new anelastically compressible model of three‐dimensional thermal convection in the “mantle” of a terrestrial planet that fully incorporates the influence of large variations in material properties. The model also incorporates the influence of (1) multiple solid‐solid pressure‐induced phase transitions, (2) transformational superplasticity at 660 km depth, and (3) the high spin‐low spin iron spin transition in ferropericlase at midmantle pressures. The message passing interface‐parallelized code is successfully tested against previously published benchmark results. The high‐resolution control volume models exhibit the same degree of radial layering as previously shown to be characteristic of otherwise identical 2‐D axisymmetric spherical models. The layering is enhanced by the presence of moderate transformational superplasticity, and in the presence of the spin crossover in ferropericlase, stagnation of cold downwellings occurs in the range of spin crossover depths (~1700 km). Although this electronic spin transition has been suggested to be invisible seismically, recent high‐pressure ab initio calculations suggest it to have a clear signature in body wave velocities which could provide an isochemical explanation of a seismological signature involving the onset of decorrelation between Vp and Vs that has come to be interpreted as requiring compositional layering.
Aerosol transport over the Andes from the Amazon Basin to the remote Pacific Ocean: A multiyear CALIOP assessment
Authors: Bourgeois Quentin , Ekman Annica M. L. , Krejci Radovan 
Published: July 2015

AbstractSix years (2007–2012) of data from the Cloud‐Aerosol Lidar with Orthogonal Polarization (CALIOP) satellite instrument were used to investigate the vertical distribution and transport of aerosols over the tropical South American continent and the southeast Pacific Ocean. The multiyear aerosol extinction assessment indicates that aerosols, mainly biomass burning particles emitted during the dry season in the Amazon Basin, are lifted in significant amounts over the Andes. The aerosols are mainly transported in the planetary boundary layer between the surface and 2 km altitude with an aerosol extinction maximum near the surface. During the transport toward the Andes, the aerosol extinction decreases at a rate of 0.02 km−1 per kilometer of altitude likely due to dilution and deposition processes. Aerosols reaching the top of the Andes, at altitudes typically between 4 and 5 km, are entrained into the free troposphere (FT) over the southeast Pacific Ocean. A comparison between CALIOP observations and ERA‐Interim reanalysis data indicates that during their long‐range transport over the tropical Pacific Ocean, these aerosols are slowly transported toward the marine boundary layer by the large‐scale subsidence at a rate of 0.4 cm s−1. The observed vertical/horizontal transport ratio is 0.7–0.8 m km−1. Continental aerosols linked to transport over the Andes can be traced on average over 4000 km away from the continent indicating an aerosol residence time of 8–9 days in the FT over the Pacific Ocean. The FT aerosol optical depth (AOD) above the Pacific Ocean near South American coast accounts on average for 6% and 25% of the total AOD during the season of low and high biomass burning, respectively. This result shows that, during the biomass burning season, continental aerosols largely influence the AOD over the remote southeast Pacific Ocean. Overall, FT AOD decrease exponentially with the distance to continental sources at a rate of about 10% per degree of longitude over the Pacific Ocean.
Assessing and improving Noah‐MP land model simulations for the central Tibetan Plateau
Authors: Gao Yanhong , Li Kai , Chen Fei , Jiang Yingsha , Lu Chungu 
Published: July 2015

AbstractThe Tibetan Plateau (TP) region experiences strong land‐atmosphere interactions, and as an elevated heating source, significantly influences the formation of the Asian monsoon. Those interactions are not well represented in current land‐surface models (LSMs), partly due to difficulties in representing heterogeneities in soil structures in LSM. Simulations using the Noah with multiparameterization options (Noah‐MP) LSM are employed to assess the relative importance of parameterizing vertical soil heterogeneity, organic matter, and soil rhizosphere and their impacts on seasonal evolution of soil temperature, soil moisture, and surface energy and water budgets at the sparsely vegetated Amdo site located in central TP. The LSM spin‐up time at the central TP depends on the complexity of the model physics, ranging from 4 years with simplest soil physics to 30 years with the addition of organic matter and spare to dense rhizosphere parameterization in Noah‐MP. Representing layered soil texture and organic matter does not improve low biases in topsoil moisture. Reducing the saturated conductivity from the mucilage in the rhizosphere produces better results. Surface sensible and latent heat fluxes are better simulated in the monsoon season as well. Adding layered soil texture and organic matter in Noah‐MP retard the thawing in deep soil layers, and the rhizosphere effect delays thawing even more in the transient season. Uncertainties in soil initialization significantly affect deep‐soil temperature and moisture, but uncertainties in atmospheric forcing conditions mainly affect topsoil variables and consequently the surface energy fluxes. Differing land‐surface physics cause 36% uncertainty in the accumulated evapotranspiration and subsurface runoff.
Retrieving the height of smoke and dust aerosols by synergistic use of VIIRS, OMPS, and CALIOP observations
Authors: Lee Jaehwa , Hsu N. Christina , Bettenhausen Corey , Sayer Andrew M. , Seftor Colin J. , Jeong Myeong‐Jae 
Published: July 2015

AbstractThis study extends the application of the previously developed Aerosol Single‐scattering albedo and layer Height Estimation (ASHE) algorithm, which was originally applied to smoke aerosols only, to both smoke and dust aerosols by including nonspherical dust properties in the retrieval process. The main purpose of the algorithm is to derive aerosol height information over wide areas using aerosol products from multiple satellite sensors simultaneously: aerosol optical depth (AOD) and Ångström exponent from the Visible Infrared Imaging Radiometer Suite (VIIRS), UV aerosol index from the Ozone Mapping and Profiler Suite (OMPS), and total backscatter coefficient profile from the Cloud‐Aerosol Lidar with Orthogonal Polarization (CALIOP). The case studies suggest that the ASHE algorithm performs well for both smoke and dust aerosols, showing root‐mean‐square error of the retrieved aerosol height as compared to CALIOP observations from 0.58 to 1.31 km and mean bias from −0.70 to 1.13 km. In addition, the algorithm shows the ability to retrieve single‐scattering albedo to within 0.03 of Aerosol Robotic Network inversion data for moderate to thick aerosol loadings (AOD of ~1.0). For typical single‐layered aerosol cases, the estimated uncertainty in the retrieved height ranges from 1.20 to 1.80 km over land and from 1.15 to 1.58 km over ocean when favorable conditions are met. Larger errors are observed for multilayered aerosol events, due to the limited sensitivities of the passive sensors to such cases.
Knee Osteoarthritis Worsening Across the Disease Spectrum and Future Knee Pain, Symptoms, and Functioning: A Multisite Prospective Cohort Study
Authors: Riddle Daniel L. , Makowski Mateusz , Kong Xiangrong 
Published: July 2015

ObjectivePrognostic estimates for knee osteoarthritis worsening over the full disease spectrum have not been reported. Osteoarthritis Initiative data were used to determine the association between knee radiographic osteoarthritis worsening and future knee pain and function.MethodsYearly data over a 5‐year period were analyzed. Outcome measures were the Western Ontario and McMaster Universities Osteoarthritis Index and the Knee Injury and Osteoarthritis Outcome Score pain and symptoms scales. Knees were grouped based on whether yearly Kellgren/Lawrence (K/L) grades worsened. Associations of yearly K/L worsening with knee pain, symptoms, or function scores at the end of the year and with lagged outcomes observed at least 1 year after worsening were assessed using linear models with generalized estimating equations.ResultsA total of 25,932 knee‐years of observations were examined in the primary analysis. For knees with yearly K/L worsening, all outcome scores were significantly worse (P values from 0.02 to <0.001) at the end of the index year, as compared to unchanged knees. All outcomes for knees with worsened versus unchanged K/L scores exceeded the minimal clinically important difference (MCID). For lagged effects, outcomes at 1 year following the index K/L year exceeded the MCID and were statistically significant (P ≤ 0.001) for knees with baseline K/L grades of 2 or 3.ConclusionK/L worsening over a 1‐year period is prognostically important over the short term for all baseline K/L grades, and for knees with baseline K/L grades of 2 or 3 worsening continues over the following year.
Physical Activity Patterns Among Older Adults With and Without Knee Osteoarthritis in Six European Countries
Authors: Herbolsheimer Florian , Schaap Laura A. , Edwards Mark H. , Maggi Stefania , Otero Ángel , Timmermans Erik J. , Denkinger Michael D. , van der Pas Suzan , Dekker Joost , Cooper Cyrus , Dennison Elaine M. , van Schoor Natasja M. , Peter Richard ,   the Eposa Study Group
Published: July 2015

ObjectiveTo investigate patterns of physical activity in older adults with knee osteoarthritis (OA) compared to older adults without knee OA across 6 European countries. We expect country‐specific differences in the physical activity levels between persons with knee OA compared to persons without knee OA. A varying degree of physical activity levels across countries would express a facilitating or impeding influence of the social, environmental, and other contextual factors on a physically active lifestyle.MethodsBaseline cross‐sectional data from the European Project on Osteoarthritis were analyzed. In total, 2,551 participants from 6 European countries (Germany, Italy, The Netherlands, Spain, Sweden, and the UK) were included.ResultsParticipants with knee OA were less likely to follow physical activity recommendations and had poorer overall physical activity profiles than those without knee OA (mean 62.9 versus 81.5 minutes/day, respectively; P = 0.015). The magnitude of this difference varied across countries. Detailed analysis showed that low physical activity levels in persons with knee OA could be attributed to less everyday walking time (odds ratio 1.31, 95% confidence interval 1.07–1.62).ConclusionThis study highlighted the fact that having knee OA is associated with a varying degree of physical activity patterns in different countries. This national variation implies that low levels of physical activity among persons with knee OA cannot be explained exclusively by individual or disease‐specific factors, but that social, environmental, and other contextual factors should also be taken into account.
Risk of Pulmonary Embolism and Deep Venous Thrombosis in Systemic Sclerosis: A General Population‐Based Study
Authors: Schoenfeld Sara R. , Choi Hyon K. , Sayre Eric C. , Aviña‐Zubieta J. Antonio 
Published: July 2015

ObjectiveTo determine the risk of venous thromboembolism (VTE) (pulmonary embolism [PE] and deep vein thrombosis [DVT]) in individuals with incident systemic sclerosis (SSc; scleroderma) in the general population.MethodsUsing a population database that includes all residents of British Columbia, Canada, we conducted a cohort study of all patients with incident SSc and up to 10 age‐, sex‐, and entry time–matched individuals from the general population. We compared incidence rates of PE, DVT, and VTE between the 2 groups according to SSc disease duration. We calculated hazard ratios (HRs), adjusting for confounders.ResultsAmong 1,245 individuals with SSc (83% female, mean age 56 years), the incidence rates of PE, DVT, and VTE were 3.47, 3.48, and 6.56 per 1,000 person‐years, respectively, whereas the corresponding rates were 0.78, 0.76, and 1.37 per 1,000 person‐years among 12,670 non‐SSc individuals. Compared with non‐SSc individuals, the multivariable HRs among SSc patients were 3.73 (95% confidence interval [95% CI] 1.98–7.04), 2.96 (95% CI 1.54–5.69), and 3.47 (95% CI 2.14–5.64) for PE, DVT, and VTE, respectively. The age‐, sex‐, and entry time–matched HRs for PE, DVT, and VTE were highest during the first year after SSc diagnosis (32.77 [95% CI 6.60–162.75], 8.50 [95% CI 3.13–23.04], and 12.03 [95% CI 5.27–27.45], respectively).ConclusionThese findings provide population‐based evidence that SSc patients are at a substantially increased risk of VTE, especially within the first year after SSc diagnosis. Increased monitoring for this potentially fatal outcome and its modifiable risk factors is warranted in this patient population.
Synthesis and Olfactory Properties of 2‐Substituted and 2,3‐Annulated 1,4‐Dioxepan‐6‐ones
Authors: Plummer Christopher M. , Kraft Philip , Froese Jordan , Hudlický Tomáš , Rook Trevor J. , Jones Oliver A. H. , Hügel Helmut M. 
Published: July 2015

AbstractThe synthesis and olfactory properties of a series of 2‐substituted and 2,3‐annulated 1,4‐dioxepan‐6‐ones is reported. By Williamson etherification with 3‐chloro‐2‐(chloromethyl)prop‐1‐ene (6) and subsequent Katsuki–Sharpless oxidation, 1,4‐dioxepan‐6‐one (8 a) and its 2‐methyl (8 b), 2‐propyl (8 c), 2‐isobutyl (8 d), and 2,2,3,3‐tetramethyl derivative (8 e), as well as four 2,3‐annulated 1,4‐dioxepan‐6‐ones 8 h, 8 i, 8 j, and 8 k were synthesised. By etherification with ethyl diazoacetate and subsequent Dieckmann cyclisation, (5aS,9aS)‐9‐bromo‐ and 9‐iodo‐5a,6,7,9a‐tetrahydro‐2 H‐benzo[b][1,4]dioxepin‐3(4 H)‐one (8 f/g) as well as a 2,3‐annulated derivative 8 m from (+)‐limonene were prepared. 2‐Propyl‐1,4‐dioxepan‐6‐one (8 c) was discovered to have a green floral odour with anisic and cinnamic nuances, which could be rationalised by a superposition analysis. The olfactory properties of the 1,4‐dioxepan‐6‐ones synthesised underline the crucial importance of a benzenoid ring system for marine odorants.
Protein‐induzierte Farbverschiebung von Carotenoiden in β‐Crustacyanin
Authors: Gamiz‐Hernandez Ana P. , Angelova Iva Neycheva , Send Robert , Sundholm Dage , Kaila Ville R. I. 
Published: July 2015

AbstractDas Pigment β‐Crustacyanin (β‐CR) verursacht die Farbe des blauen Hummers. Wir zeigen mithilfe korrelierter Ab‐initio‐Rechnungen, wie die Proteinumgebung die Farbe der β‐CR‐Farbstoffe mittels elektrostatischer und sterischer Effekte bestimmt.