bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling the stable water isotope expression of El Niño in the Pliocene: Implications for the interpretation of proxy data
Authors: Tindall Julia C. , Haywood Alan M. , Thirumalai Kaustubh 
Published: July 2017

AbstractThe El Niño–Southern Oscillation (ENSO) drives interannual climate variability; hence, its behavior over a range of climates needs to be understood. It is therefore important to verify that the paleoarchives, used for preinstrumental ENSO studies, can accurately record ENSO signals. Here we use the isotope enabled Hadley Centre General Circulation Model, HadCM3, to investigate ENSO signals in paleoarchives from a warm paleoclimate, the mid‐Pliocene Warm Period (mPWP: 3.3–3.0 Ma). Continuous (e.g., coral) and discrete (e.g., foraminifera) proxy data are simulated throughout the tropical Pacific, and ENSO events suggested by the pseudoproxy data are assessed using modeled ENSO indices. HadCM3 suggests that the ability to reconstruct ENSO from coral data is predominantly dependent on location. However, since modeled ENSO is slightly stronger in the mPWP than the preindustrial, ENSO is slightly easier to detect in mPWP aged coral. HadCM3 also suggests that using statistics from a number of individual foraminifera (individual foraminifera analysis, IFA) generally provides more accurate ENSO information for the mPWP than for the preindustrial, particularly in the western and central Pacific. However, a test case from the eastern Pacific showed that for some locations, the IFA method can work well for the preindustrial but be unreliable for a different climate. The work highlights that sites used for paleo‐ENSO analysis should be chosen with extreme care in order to avoid unreliable results. Although a site with good skill for preindustrial ENSO will usually have good skill for assessing mPWP ENSO, this is not always the case.
Evidence of a modern deep water magmatic hydrothermal system in the Canary Basin (eastern central Atlantic Ocean)
Authors: Medialdea T. , Somoza L. , González F. J. , Vázquez J. T. , de Ignacio C. , Sumino H. , Sánchez‐Guillamón O. , Orihashi Y. , León R. , Palomino D. 
Published: July 2017

AbstractNew seismic profiles, bathymetric data, and sediment‐rock sampling document for the first time the discovery of hydrothermal vent complexes and volcanic cones at 4800–5200 m depth related to recent volcanic and intrusive activity in an unexplored area of the Canary Basin (Eastern Atlantic Ocean, 500 km west of the Canary Islands). A complex of sill intrusions is imaged on seismic profiles showing saucer‐shaped, parallel, or inclined geometries. Three main types of structures are related to these intrusions. Type I consists of cone‐shaped depressions developed above inclined sills interpreted as hydrothermal vents. Type II is the most abundant and is represented by isolated or clustered hydrothermal domes bounded by faults rooted at the tips of saucer‐shaped sills. Domes are interpreted as seabed expressions of reservoirs of CH4 and CO2‐rich fluids formed by degassing and contact metamorphism of organic‐rich sediments around sill intrusions. Type III are hydrothermal‐volcanic complexes originated above stratified or branched inclined sills connected by a chimney to the seabed volcanic edifice. Parallel sills sourced from the magmatic chimney formed also domes surrounding the volcanic cones. Core and dredges revealed that these volcanoes, which must be among the deepest in the world, are constituted by OIB‐type, basanites with an outer ring of blue‐green hydrothermal Al‐rich smectite muds. Magmatic activity is dated, based on lava samples, at 0.78 ± 0.05 and 1.61 ± 0.09 Ma (K/Ar methods) and on tephra layers within cores at 25–237 ky. The Subvent hydrothermal‐volcanic complex constitutes the first modern system reported in deep water oceanic basins related to intraplate hotspot activity.
Explaining extreme ground motion in Osaka basin during the 2011 Tohoku earthquake
Authors: Tsai Victor C. , Bowden Daniel C. , Kanamori Hiroo 
Published: July 2017

AbstractDespite being 770 km away from the epicenter, observed ground motions due to the Tohoku earthquake in the Osaka Basin were unexpectedly large, with an amplification of more than a factor of 20 compared to immediately outside the basin, and including 2.7 m peak‐to‐peak roof displacements at one high‐rise building. The local ground motions exceeded expectations based on standard computations of site response by a factor of 3, predicted frequencies of peak acceleration were off by at least 50%, and such discrepancies have not yet been explained quantitatively. Here we show that utilizing semianalytic theory for surface‐wave amplification, we are able to accurately predict both the amplitudes and frequencies of large ground amplification in the Osaka Basin using only knowledge of the local one‐dimensional structure. Comparison between this simple prediction and observed amplification was not expected to be so favorable and suggests that simple one‐dimensional surface‐wave site amplification factors can be useful in the absence of full three‐dimensional wave propagation simulations. Such surface‐wave amplification factors can be included in addition to the standard measures of site‐specific site amplification and should help explain strong ground motion variability in future large earthquakes that shake Osaka Basin and elsewhere in the world.
THEMIS multispacecraft observations of a reconnecting magnetosheath current sheet with symmetric boundary conditions and a large guide field
Authors: Øieroset M. , Phan T. D. , Shay M. A. , Haggerty C. C. , Fujimoto M. , Angelopoulos V. , Eastwood J. P. , Mozer F. S. 
Published: July 2017

AbstractWe report three spacecraft observations of a reconnecting magnetosheath current sheet with a guide field of unity, with THEMIS D (THD) and THEMIS E (THE)/THEMIS A (THA) observing oppositely directed reconnection exhausts, indicating the presence of an X line between the spacecraft. The near‐constant convective speed of the magnetosheath current sheet allowed the direct translation of the observed time series into spatial profiles. THD observed asymmetries in the plasma density and temperature profiles across the exhaust, characteristics of symmetric reconnection with a guide field. The exhausts at THE and THA, on the other hand, were not the expected mirror image of the THD exhaust in terms of the plasma and field profiles. They consisted of a main outflow at the center of the current sheet, flanked by oppositely directed flows at the two edges of the current sheet, suggesting the presence of a second X line, whose outflow wraps around the outflow from the first X line.
On the violation of gradient wind balance at the top of tropical cyclones
Authors: Cohen Yair , Harnik Nili , Heifetz Eyal , Nolan David S. , Tao Dandan , Zhang Fuqing 
Published: July 2017

AbstractThe existence of physical solutions for the gradient wind balance is examined at the top of 12 simulated tropical cyclones. The pressure field at the top of these storms, which depends on the vertically integrated effect of the warm core and the near surface low, is found to violate the gradient wind balance—termed here as a state of nonbalance. Using a toy model, it is shown that slight changes in the relative location and relative widths of the warm core drastically increase the isobaric curvature at the upper level pressure maps leading to nonbalance. While idealized storms return to balance within several days, simulations of real‐world tropical cyclones retain a considerable degree of nonbalance throughout the model integration. Comparing mean and maximum values of different storms shows that peak nonbalance correlates with either peak intensity or intensification, implying the possible importance of nonbalance at upper levels for the near surface winds.
WN4 variability in DMSP ion densities across season, solar cycle, and local time
Authors: Hawkins J. M. , Anderson P. C. 
Published: July 2017

AbstractNonmigrating tides are a major coupling mechanism between the different regions of the atmosphere and ionosphere. The wave number 4 (WN4) pattern in the ionosphere has been recognized as originating primarily with the diurnal eastward propagating wave‐3 nonmigrating tide (DE3) in the troposphere, and significant effort has been devoted in recent years to understanding how tidal effects manifest in various physical parameters across a very wide range of altitudes. While DE3 and WN4 signatures have been much studied in the mesosphere‐lower thermosphere region, relatively little is known about how WN4 impacts the ionosphere above the F peak. We present an analysis of WN4 in the topside ionosphere as measured by the Defense Meteorological Satellite Program (DMSP) spacecraft, using monthly averages of total ion densities and composition binned by latitude and longitude. We found that WN4 is most strongly present during September equinox. In May–August, ion densities near 180–270 geographic longitude (GLON) are enhanced and the WN4 pattern moves 5–10° north; in November–February, ion densities are reduced in this region and WN4 moves 5–10° south. No solar cycle effects were found in the magnitude of dN/N. The longitude position of the peaks (phase) was observed to vary by about 10° with F10.7, moving eastward with increasing F10.7. The latitude variation was less than 5° and did not show a trend with F10.7. The WN4 pattern changes rapidly near dawn but is very constant throughout the afternoon and evening in terms of dN/N and drifts eastward at about 2° GLON per hour magnetic local time.
Systems science of the magnetosphere: Creating indices of substorm activity, of the substorm‐injected electron population, and of the electron radiation belt
Authors: Borovsky Joseph E. , Yakymenko Kateryna 
Published: July 2017

AbstractTo more fully monitor the elements of the magnetosphere‐ionosphere system and its activity, indices are created to quantify the rate of substorm onset occurrence, the rate of substorm activations, the intensity of the 130 keV substorm‐injected electrons and the intensity of the 1.2 MeV radiation‐belt electrons. The reactions of these various indices to the onset of isolated substorms are examined, and the behaviors of the indices are explored before and during high‐speed‐stream‐driven storms and during solar wind rarefactions after high‐speed streams. Autocorrelation functions of the indices are analyzed and compared with autocorrelation functions of solar wind parameters and geomagnetic indices. Lagged‐time correlations between the indices and solar wind variables and geomagnetic indices are surveyed. These 1 h resolution indices are available to the research community.
Coupling between Mercury and its nightside magnetosphere: Cross‐tail current sheet asymmetry and substorm current wedge formation
Authors: Poh Gangkai , Slavin James A. , Jia Xianzhe , Raines Jim M. , Imber Suzanne M. , Sun Wei‐Jie , Gershman Daniel J. , DiBraccio Gina A. , Genestreti Kevin J. , Smith Andy W. 
Published: July 2017

AbstractWe analyzed MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) magnetic field and plasma measurements taken during 319 crossings of Mercury's cross‐tail current sheet. We found that the measured BZ in the current sheet is higher on the dawnside than the duskside by a factor of ≈3 and the asymmetry decreases with downtail distance. This result is consistent with expectations based upon MHD stress balance. The magnetic fields threading the more stretched current sheet in the duskside have a higher plasma beta than those on the dawnside, where they are less stretched. This asymmetric behavior is confirmed by mean current sheet thickness being greatest on the dawnside. We propose that heavy planetary ion (e.g., Na+) enhancements in the duskside current sheet provides the most likely explanation for the dawn‐dusk current sheet asymmetries. We also report the direct measurement of Mercury's substorm current wedge (SCW) formation and estimate the total current due to pileup of magnetic flux to be ≈11 kA. The conductance at the foot of the field lines required to close the SCW current is found to be ≈1.2 S, which is similar to earlier results derived from modeling of Mercury's Region 1 field‐aligned currents. Hence, Mercury's regolith is sufficiently conductive for the current to flow radially then across the surface of Mercury's highly conductive iron core. Mercury appears to be closely coupled to its nightside magnetosphere by mass loading of upward flowing heavy planetary ions and electrodynamically by field‐aligned currents that transfer momentum and energy to the nightside auroral oval crust and interior. Heavy planetary ion enhancements in Mercury's duskside current sheet provide explanation for cross‐tail asymmetries found in this study. The total current due to the pileup of magnetic flux and conductance required to close the SCW current is found to be ≈11 kA and 1.2 S. Mercury is coupled to magnetotail by mass loading of heavy ions and field‐aligned currents driven by reconnection‐related fast plasma flow.
Runup of granular landslide‐generated tsunamis on planar coasts and conical islands
Authors: McFall Brian C. , Fritz Hermann M. 
Published: July 2017

AbstractLarge‐scale physical model experiments of tsunamis generated by granular landslides and volcanic flank collapses are conducted to study the wave runup on both the hill slope laterally adjacent to the landslide and an opposing hill slope. A pneumatic landslide tsunami generator was deployed on planar and convex conical hill slopes to simulate deformable landslides with various geometries and kinematics. On the landslide hill slope, maximum runup and rundown were observed in the landslide impact region followed by adjacent second maxima after the lateral waves were fully formed. The runup and rundown decayed asymptotically from the second maxima. In the conical island scenario, a localized runup amplification was measured on the lee side of the island. Outside the landslide impact region, the effects of the landslide granulometry on the lateral wave runup are minimal. The lateral wave runup on the planar hill slope was generally larger than on the convex conical hill slope outside the landslide impact region. The convex conical hill slope traps less lateral wave energy. The zeroth mode of the edge wave dispersion relation matched the first and second lateral waves on the planar hill slope and the first wave on the convex conical hill slope. Predictive equations for the laterally propagating wave characteristics are derived and a method to predict the runup on an opposing hill slope is presented. The predictive wave and runup equations are benchmarked against the 2007 landslide‐generated tsunami in Chehalis Lake, British Columbia, Canada.
The responses of the Hadley circulation to different meridional SST structures in the seasonal cycle
Authors: Feng Juan , Li Jianping , Jin Feifei , Zhao Sen , Xie Fei 
Published: July 2017

AbstractThe meridional structure of sea surface temperature (SST) plays an important role in determining the variations of the Hadley circulation (HC). The quantitative differences in the HC caused by the changing meridional structures of SST over seasonal cycles remain unclear. To determine the quantitative response of the HC to the meridional structure of SST during the seasonal cycle, this study decomposes the variations of the SST and HC into two components: equatorially asymmetric components (i.e., SEA for SST and HEA for HC) and equatorially symmetric components (i.e., SES for SST and HES for HC). Variations in HEA (HES) are closely associated with those in SEA (SES). In this study, five atmospheric reanalyses and two SST reanalyses are analyzed, focusing on the period of 1979–2013. The response amplitude of HEA to SEA is about four times than that of HES to SES in most of the reanalyses. This result provides a possible explanation for the dominance of the equatorially asymmetric mode over the variability of the HC during the seasonal march.
The El Niño–Southern Oscillation effect on tropical outgoing longwave radiation: A daytime versus nighttime perspective
Authors: Su Wenying , Loeb Norman G. , Liang Lusheng , Liu Nana , Liu Chuntao 
Published: July 2017

AbstractTrends of tropical (30°N–30°S) mean daytime and nighttime outgoing longwave radiations (OLRs) from the Clouds and Earth's Radiant Energy System (CERES) and the Atmospheric Infrared Sounder (AIRS) are analyzed using data from 2003 to 2013. Both the daytime and nighttime OLRs from these instruments show decreasing trends because of El Niño conditions early in the period and La Niña conditions at the end. However, the daytime and nighttime OLRs decrease at different rates with the OLR decreasing faster during daytime than nighttime. The daytime‐nighttime OLR trend is consistent across CERES Terra, Aqua observations, and computed OLR based upon AIRS and Moderate‐Resolution Imaging Spectroradiometer (MODIS) retrievals. To understand the cause of the differing decreasing rates of daytime and nighttime OLRs, high cloud fraction and effective temperature are examined using cloud retrievals from MODIS and AIRS. Unlike the very consistent OLR trends between CERES and AIRS, the trends in cloud properties are not as consistent, which are likely due to the different cloud retrieval methods used. When MODIS and AIRS cloud properties are used to compute OLR, the daytime and nighttime OLR trends based upon MODIS cloud properties are approximately half as large as the trends from AIRS cloud properties, but their daytime‐nighttime OLR trends are in agreement. This demonstrates that though the current cloud retrieval algorithms lack the accuracy to pinpoint the changes of daytime and nighttime clouds in the tropics, they do provide a radiatively consistent view for daytime and nighttime OLR changes. The causes for the larger decreasing daytime OLR trend than that for nighttime OLR are not clear and further studies are needed.
A methodology for reduced order modeling and calibration of the upper atmosphere
Authors: Mehta Piyush M. , Linares Richard 
Published: July 2017

AbstractAtmospheric drag is the largest source of uncertainty in accurately predicting the orbit of satellites in low Earth orbit (LEO). Accurately predicting drag for objects that traverse LEO is critical to space situational awareness. Atmospheric models used for orbital drag calculations can be characterized either as empirical or physics‐based (first principles based). Empirical models are fast to evaluate but offer limited real‐time predictive/forecasting ability, while physics based models offer greater predictive/forecasting ability but require dedicated parallel computational resources. Also, calibration with accurate data is required for either type of models. This paper presents a new methodology based on proper orthogonal decomposition toward development of a quasi‐physical, predictive, reduced order model that combines the speed of empirical and the predictive/forecasting capabilities of physics‐based models. The methodology is developed to reduce the high dimensionality of physics‐based models while maintaining its capabilities. We develop the methodology using the Naval Research Lab's Mass Spectrometer Incoherent Scatter model and show that the diurnal and seasonal variations can be captured using a small number of modes and parameters. We also present calibration of the reduced order model using the CHAMP and GRACE accelerometer‐derived densities. Results show that the method performs well for modeling and calibration of the upper atmosphere.
Effects of collimator angle, couch angle, and starting phase on motion‐tracking dynamic conformal arc therapy (4D DCAT)
Authors: Xu Zhengzheng , Yao Rutao , Podgorsak Matthew B. , Wang Iris Z. 
Published: July 2017

AbstractPurposeThe aim of this study was to find an optimized configuration of collimator angle, couch angle, and starting tracking phase to improve the delivery performance in terms of MLC position errors, maximal MLC leaf speed, and total beam‐on time of DCAT plans with motion tracking (4D DCAT).Method and materialsNontracking conformal arc plans were first created based on a single phase (maximal exhalation phase) of a respiratory motion phantom with a spherical target. An ideal model was used to simulate the target motion in superior‐inferior (SI), anterior‐posterior (AP), and left‐right (LR) dimensions. The motion was decomposed to the MLC leaf position coordinates for motion compensation and generating 4D DCAT plans. The plans were studied with collimator angle ranged from 0° to 90°; couch angle ranged from 350°(−10°) to 10°; and starting tracking phases at maximal inhalation () and exhalation () phases. Plan performance score (PPS) evaluates the plan complexity including the variability in MLC leaf positions, degree of irregularity in field shape and area. PPS ranges from 0 to 1, where low PPS indicates a plan with high complexity. The 4D DCAT plans with the maximal and the minimal PPS were selected and delivered on a Varian TrueBeam linear accelerator. Gafchromic‐EBT3 dosimetry films were used to measure the dose delivered to the target in the phantom. Gamma analysis for film measurements with 90% passing rate threshold using 3%/3 mm criteria and trajectory log files were analyzed for plan delivery accuracy evaluation.ResultsThe maximal PPS of all the plans was 0.554, achieved with collimator angle at 87°, couch angle at 350°, and starting phase at maximal inhalation (). The maximal MLC leaf speed, MLC leaf errors, total leaf travel distance, and beam‐on time were 20 mm/s, 0.39 ± 0.16 mm, 1385 cm, and 157 s, respectively. The starting phase, whether at maximal inhalation or exhalation had a relatively small contribution to PPS (0.01 ± 0.05).ConclusionsBy selecting collimator angle, couch angle, and starting tracking phase, 4D DCAT plans with the maximal PPS demonstrated less MLC leaf position errors, lower maximal MLC leaf speed, and shorter beam‐on time which improved the performance of 4D motion‐tracking DCAT delivery.
Physical Functioning, Pain, and Health‐Related Quality of Life in Adults With Juvenile Idiopathic Arthritis: A Longitudinal 30‐Year Followup Study
Authors: Tollisen Anita , Selvaag Anne M. , Aulie Hanne A. , Lilleby Vibke , Aasland Astrid , Lerdal Anners , Flatø Berit 
Published: July 2017

ObjectiveTo describe physical functioning, pain, and health‐related quality of life (HRQoL) in adults with juvenile idiopathic arthritis (JIA), investigate changes over time, and identify predictors of poorer HRQoL after 30 years of disease.MethodsPatients (n = 176) clinically examined after 15 years were reassessed using the Health Assessment Questionnaire disability index (HAQ DI), the visual analog scale pain subscale (VAS pain), and the Medical Outcomes Study Short Form 36 (SF‐36) after 23 years and 30 years. Patients with signs of active disease after a minimum of 15 years were clinically examined again at 30 years. Patients were compared to matched controls.ResultsAt the 30‐year followup, 82 patients (47%) had HAQ DI scores >0, and the median VAS pain score in patients was 0.6 (range 0–10). Patients had lower SF‐36 physical component summary (PCS) scores compared with controls (P < 0.001), and this was evident for patients both with and without clinical remission (P ≤ 0.01). No group differences were found in SF‐36 mental component summary scores. Patients also scored worse than controls on all SF‐36 subscales (P ≤ 0.01) except mental health. PCS scores worsened significantly between the 15‐ and 30‐year followup time points (P = 0.001). Worse HAQ DI, VAS pain, and patient's global assessment of well‐being scores, and receiving disability/social living allowance at 30 years, were correlated with lower PCS scores. Worse HAQ DI, patient's global assessment of well‐being, and VAS fatigue scores at 15‐year followup predicted lower PCS scores at 30‐year followup.ConclusionJIA had a detrimental effect on physical HRQoL as measured by the PCS of the SF‐36. The strongest correlates were physical disability, pain, fatigue, well‐being, and receiving disability/social living allowance.