bluuebunny/crossref_metadata_2025_split huggingface dataset:
Time‐Dependent Freshwater Input From Ice Shelves: Impacts on Antarctic Sea Ice and the Southern Ocean in an Earth System Model
Authors: Pauling Andrew G. , Smith Inga J. , Langhorne Patricia J. , Bitz Cecilia M. 
Published: October 2017

AbstractEarth System Models do not reproduce the observed increase in Antarctic sea ice extent which may be due to the unrealistic representation of ice shelves. Here we investigate the response of sea ice to increasing freshwater input from ice shelves using the Community Earth System Model with the Community Atmosphere Model version 5 [CESM1(CAM5)]. We have conducted model experiments adding fresh water as if from ice shelf melt with a linear increase in the rate of input over the period 1980–2013. Including the effect of heat loss from the ocean to melt ice shelves resulted in significantly more positive trends in sea ice area. We found that an increase in the rate of change of freshwater input of ∼45 Gt yr−2 was sufficient to offset the negative trend in sea ice area in CESM1(CAM5), although the freshwater input by the end of the experiment was larger than observed at that time.
Dam Construction in Lancang‐Mekong River Basin Could Mitigate Future Flood Risk From Warming‐Induced Intensified Rainfall
Authors: Wang Wei , Lu Hui , Ruby Leung L. , Li Hong‐Yi , Zhao Jianshi , Tian Fuqiang , Yang Kun , Sothea Khem 
Published: October 2017

AbstractWater resources management, in particular flood control, in the Lancang‐Mekong River Basin (LMRB) faces two key challenges in the 21st century: climate change and dam construction. A large‐scale distributed Geomorphology‐Based Hydrological Model coupled with a simple reservoir regulation model (GBHM‐LMK‐SOP) is used to investigate the relative effects of climate change and dam construction on the flood characteristics in the LMRB. Results suggest an increase in both flood magnitude and frequency under climate change, which is more severe in the upstream basin and increases over time. However, stream regulation by dam reduces flood risk consistently throughout this century, with more obvious effects in the upstream basin where larger reservoirs will be located. The flood mitigation effect of dam regulation dominates over the flood intensification effect of climate change before 2060, but the latter emerges more prominently after 2060 and dominates the flood risk especially in the lower basin.
Highly Variable Latest Pleistocene‐Holocene Incremental Slip Rates on the Awatere Fault at Saxton River, South Island, New Zealand, Revealed by Lidar Mapping and Luminescence Dating
Authors: Zinke Robert , Dolan James F. , Rhodes Edward J. , Van Dissen Russ , McGuire Christopher P. 
Published: October 2017

AbstractGeomorphic mapping using high‐resolution lidar imagery and luminescence dating reveal highly variable incremental Holocene‐latest Pleistocene slip rates at the well‐known Saxton River site along the Awatere fault, a dextral strike‐slip fault in the Marlborough Fault System, South Island, New Zealand. Using lidar and field observations, we measured seven fault offsets recorded by fluvial terraces and bedrock markers. Improved dating of the offsets is provided by post‐IR‐IRSL225 luminescence ages. Incremental slip rates varied from <2 mm/yr to >15 mm/yr over intervals of thousands of years and tens of meters of slip, demonstrating order‐of‐magnitude temporal variations in rate at a single site. These observations have basic implications for earthquake fault behavior, lithospheric mechanics, discrepancies between geodetic and geologic slip rates, and probabilistic seismic hazard assessment.
Drivers of Continued Surface Warming After Cessation of Carbon Emissions
Authors: Williams Richard G. , Roussenov Vassil , Frölicher Thomas L. , Goodwin Philip 
Published: October 2017

AbstractThe climate response after cessation of carbon emissions is examined here, exploiting a single equation connecting surface warming to cumulative carbon emissions. The multicentennial response to an idealized pulse of carbon is considered by diagnosing a 1,000 year integration of an Earth system model (Geophysical Fluid Dynamics Laboratory ESM2M) and an ensemble of efficient Earth system model simulations. After emissions cease, surface temperature evolves according to (i) how much of the emitted carbon remains in the atmosphere and (ii) how much of the additional radiative forcing warms the surface rather than the ocean interior. The peak in surface temperature is delayed in time after carbon emissions cease through the decline in ocean heat uptake, which in turn increases the proportion of radiative forcing warming the surface. Eventually, after many centuries, surface temperature declines as the radiative forcing decreases through the excess atmospheric CO2 being taken up by the ocean and land.
Evidence for the Interior Evolution of Ceres from Geologic Analysis of Fractures
Authors: Scully J. E. C. , Buczkowski D. L. , Schmedemann N. , Raymond C. A. , Castillo‐Rogez J. C. , King S. D. , Bland M. T. , Ermakov A. I. , O'Brien D. P. , Marchi S. , Longobardo A. , Russell C. T. , Fu R. R. , Neveu M. 
Published: October 2017

AbstractCeres is the largest asteroid belt object, and the Dawn spacecraft observed Ceres since 2015. Dawn observed two morphologically distinct linear features on Ceres's surface: secondary crater chains and pit chains. Pit chains provide unique insights into Ceres's interior evolution. We interpret pit chains called the Samhain Catenae as the surface expression of subsurface fractures. Using the pit chains' spacings, we estimate that the localized thickness of Ceres's fractured, outer layer is approximately ≥58 km, at least ~14 km greater than the global average. We hypothesize that extensional stresses, induced by a region of upwelling material arising from convection/diapirism, formed the Samhain Catenae. We derive characteristics for this upwelling material, which can be used as constraints in future interior modeling studies. For example, its predicted location coincides with Hanami Planum, a high‐elevation region with a negative residual gravity anomaly, which may be surficial evidence for this proposed region of upwelling material.
Large‐Scale Seasonal Changes in Glacier Thickness Across High Mountain Asia
Authors: Wang Qiuyu , Yi Shuang , Chang Le , Sun Wenke 
Published: October 2017

AbstractRecently, increased efforts have been made to estimate the mass budgets of glaciers in High Mountain Asia (HMA). However, seasonal changes in glaciers are poorly understood, despite the fact that seasonal meltwater released from glaciers is a crucial local water resource in HMA. Utilizing satellite altimetry and gravimetry data, we constructed annual changes in glacier elevation and identified two general patterns of the seasonality of glacier elevation changes. Glaciers in the periphery of HMA (except for those in the eastern Himalayas) thicken from approximately December to April–June, thus exhibiting winter and spring accumulation. Glaciers in the inner Tibetan Plateau, especially those in Western Kunlun and Tanggula, accumulate from approximately March to approximately August, thus exhibiting spring and summer accumulation. The amounts of seasonal glacier ablation were obtained using a new approach of direct observations of glacier changes, rather than inferring changes using a climate model.
The Attenuation of Swell Waves by Rain
Authors: Cavaleri Luigi , Bertotti Luciana 
Published: October 2017

AbstractWithin the progressive improvement in wave modeling we focus on the attenuation of swell waves by rain. Till now ignored, the process is shown to be relevant, especially for the correct estimate of swell. Following the practical impossibility of devoted field experiments, we exploit the global model results over a period of more than four years to extract the tiny signal associated to the attenuation by rain. A direct comparison of the ratio model by altimeter significant wave heights versus the encountered rain amount hints to a marked related dependence. A proper quantification of the related physical effect requires a multiple step procedure that we describe in detail. We check the reliability of the results, and we provide the related source function ready for implementation in operational wave models.
Getting It Right Matters: Temperature Goal Interpretations in Geoscience Research
Authors: Rogelj Joeri , Schleussner Carl‐Friedrich , Hare William 
Published: October 2017

AbstractThe adoption of the 1.5°C long‐term warming limit in the Paris Agreement made 1.5°C a “hot topic” in the scientific community, with researchers eager to address this issue. Long‐term warming limits have a decade‐long history in international policy. To effectively inform the climate policy debate, geoscience research hence needs a core understanding of their legal and policy context. Here we describe this context in detail and illustrate its importance by showing the impact it can have on global carbon budget estimates. We show that definitional clarity is essential on this important matter.
Evidence of the Lower Thermospheric Winter‐to‐Summer Circulation From SABER CO2 Observations
Authors: Qian Liying , Burns Alan , Yue Jia 
Published: October 2017

AbstractNumerical studies have shown that there is a lower thermospheric winter‐to‐summer circulation that is driven by wave dissipation and that it plays a significant role in trace gas distributions in the mesosphere and lower thermosphere, and in the composition of the thermosphere. However, the characteristics of this circulation are poorly known. Direct observations of it are difficult, but it leaves clear signatures in tracer distributions. The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) onboard the Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite has obtained CO2 concentration from 2002 to present. This data set, combined with simulations by the Whole Atmosphere Community Climate Model, provides an unprecedented opportunity to infer the morphology of this circulation in both the summer and winter hemispheres. Our study show that there exists a maximum vertical gradient of CO2 at summer high latitudes, driven by the convergence of the upwelling of the mesospheric circulation and the downwelling of the lower thermospheric circulation; in the winter hemisphere, the maximum vertical gradient of CO2 is located at a higher altitude, driven by the convergence of the upwelling of the lower thermospheric circulation and the downwelling of the solar‐driven thermospheric circulation; the bottom of the lower thermospheric circulation is located between ~ 95 km and 100 km, and it has a vertical extent of ~10 km. Analysis of the SABER CO2 and temperature at summer high latitudes showed that the bottom of this circulation is consistently higher than the mesopause height by ~10 km.
A Shallow Seismic Velocity Model for the Groningen Area in the Netherlands
Authors: Hofman L. J. , Ruigrok E. , Dost B. , Paulssen H. 
Published: October 2017

AbstractThe province of Groningen in the Netherlands holds one of the world's largest natural gas fields, and it has been an important source of energy for Western Europe for many decades. The seismicity in recent years called for a better understanding of the local subsurface, and therefore a dense network of 70 boreholes was installed in early 2015. Each borehole is equipped with four geophones and a surface accelerometer. In this study, data from this network are used to determine the shallow velocity structure that is important for the quantification of the seismic hazard and accurate source localizations. Compressional and shear wave velocity profiles with uncertainties are derived for each of the 200 m deep boreholes using passive seismic interferometry applied to local event data. The resulting seismic velocity distributions are presented as contour maps for 50 m depth intervals. The maps show strong lateral variations, where areas of low VP/VS ratio correspond to regions of sedimentary infill. The shear wave velocities were derived using the transverse component seismograms. Because the sensor orientations of the borehole geophones were unknown, they had to be determined first. This was done using a novel method based on cross correlations between the geophones and their colocated surface accelerometer. In addition, by extensive cross‐correlation analysis over the network, several installation inconsistencies were identified and resolved.
Unusual Strong Ground Motion Across Japan From the 680 km Deep 30 May 2015 Ogasawara Islands Earthquake
Authors: Furumura Takashi , Kennett Brian L. N. 
Published: October 2017

AbstractThe Mw 7.9 earthquake beneath the Ogasawara Islands on 2015 May 30 at 680 km depth (about 100 km deeper than other seismicity in the vicinity) produced significant shaking over a broad area of Japan in the epicentral distance range 1,000–2,000 km. Usually, deep earthquakes in the subducting Pacific slab develop a band of large ground motion along the east coast of northern Japan, due to efficient guiding of high‐frequency (>1 Hz) waves in the subducting slab. However, for this very deep earthquake, the large ground acceleration arises from relatively low‐frequency (<1 Hz) S wave pulses with a long tail of long‐period (<0.1 Hz) signals. The arrival of the slab‐guided high‐frequency signal was very late, and weak, compared with normal Pacific slab events. Numerical simulation of seismic wave propagation reveals that the observed low‐frequency pulses are the direct S wave from the very deep source followed by a large SV‐to‐P conversion at the free surface with near‐critical S wave incidence. These phases produce a long‐period shear‐coupled PL (S‐PL) wave by constructive interference between wide‐angle P and S reflections in the crust and incoming S wave to the crust. The S‐PL wave travels several hundred kilometers at regional distances with reinforcement from continuing S wave input from the very deep source. Such an unusual observation of strong low‐frequency ground motion was due to its very great source depth, outside the main slab, so the high‐frequency Pacific‐slab guided wave was weak.
Nonmonotonicity of the Frictional Bimaterial Effect
Authors: Aldam Michael , Xu Shiqing , Brener Efim A. , Ben‐Zion Yehuda , Bouchbinder Eran 
Published: October 2017

AbstractSliding along frictional interfaces separating dissimilar elastic materials is qualitatively different from sliding along interfaces separating identical materials due to the existence of an elastodynamic coupling between interfacial slip and normal stress perturbations in the former case. This bimaterial coupling has important implications for the dynamics of frictional interfaces, including their stability and rupture propagation along them. We show that while this bimaterial coupling is a monotonically increasing function of the bimaterial contrast, when it is coupled to interfacial shear stress perturbations through a friction law, various physical quantities exhibit a nonmonotonic dependence on the bimaterial contrast. In particular, we show that for a regularized Coulomb friction, the maximal growth rate of unstable interfacial perturbations of homogeneous sliding is a nonmonotonic function of the bimaterial contrast and provides analytic insight into the origin of this nonmonotonicity. We further show that for velocity‐strengthening rate‐and‐state friction, the maximal growth rate of unstable interfacial perturbations of homogeneous sliding is also a nonmonotonic function of the bimaterial contrast. Results from simulations of dynamic rupture along a bimaterial interface with slip‐weakening friction provide evidence that the theoretically predicted nonmonotonicity persists in nonsteady, transient frictional dynamics.
Constraining the Date of the Martian Dynamo Shutdown by Means of Crater Magnetization Signatures
Authors: Vervelidou Foteini , Lesur Vincent , Grott Matthias , Morschhauser Achim , Lillis Robert J. 
Published: October 2017

AbstractMars is believed to have possessed a dynamo that ceased operating approximately 4 Ga ago, although the exact time is still under debate. The scope of this study is to constrain the possible timing of its cessation by studying the magnetization signatures of craters. The study uses the latest available model of the lithospheric magnetic field of Mars, which is based on Mars Global Surveyor data. We tackle the problem of nonuniqueness that characterizes the inversion of magnetic field data for the magnetization by inferring only the visible part of the magnetization, that is, the part of the magnetization that gives rise to the observed magnetic field. Further on, we demonstrate that a zero visible magnetization is a valid proxy for the entire magnetization being zero under the assumption of a magnetization distribution of induced geometry. This assumption holds for craters whose thermoremanent magnetization has not been significantly altered since its acquisition. Our results show that the dynamo shut off after the impacts that created the Acidalia and SE Elysium basins and before the crust within the Utopia basin cooled below its magnetic blocking temperature. Accounting for the age uncertainties in the dating of these craters, we estimate that the dynamo shut off at an N(300) crater retention age of 2.5–3.2 or an absolute model age of 4.12–4.14 Ga. Moreover, the Martian dynamo may have been weaker in its early stage, which if true implies that the driving mechanism of the Martian dynamo was not the same throughout its history.
Numerical Analysis of the Potential Formulation of the Volume Integral Equation for Electromagnetic Scattering
Authors: Markkanen Johannes 
Published: October 2017

AbstractWe present a discretization of the potential volume integral equation for electromagnetic scattering by dielectric objects. The equations are written for the vector and scalar potentials combined with the Lorenz gauge condition. The advantage of the potential formulation over the more conventional formulations, that is, the field, flux, or current formulations, is that the potentials are continuous across material interfaces enabling the use of fully continuous basis functions. The discretization with the fully continuous basis functions leads to a better conditioned system matrix compared to those of the other formulations discretized with the fully or partially discontinuous functions. Thus, it speeds up the iterative solution. The method is accelerated with the precorrected fast Fourier transform algorithm.
Comment on “U‐Pb and Hf Isotope Analysis of Detrital Zircons From Mesozoic Strata of the Gravina Belt, Southeast Alaska” by Yokelson Et Al. (2015)
Authors: Lowey Grant W. 
Published: October 2017

AbstractYokelson et al. (2015) present U‐Pb and Hf isotope analyses of detrital zircons from the Gravina belt showing that the western facies was derived from the west and the eastern facies was derived from the east and concluded that this is evidence that a west dipping subduction zone did not exist along the inboard margin of the Alexander‐Wrangellia terrane during Late Jurassic‐Early Cretaceous time as proposed by Sigloch and Mihalynuk (2013). However, the tectonic affinity of the eastern Gravina belt is open to debate, and Yokelson et al.'s (2015) claim that the Sigloch and Mihalynuk (2013) model of west dipping subduction was implausible is based on an incorrect assumption.
Synoptic Sampling to Determine Distributed Groundwater‐Surface Water Nitrate Loading and Removal Potential Along a Lowland River
Authors: Pai Henry , Villamizar Sandra R. , Harmon Thomas C. 
Published: October 2017

AbstractDelineating pollutant reactive transport pathways that connect local land use patterns to surface water is an important goal. This work illustrates high‐resolution river mapping of salinity or specific conductance (SC) and nitrate (
) as a potential part of achieving this goal. We observed longitudinal river SC and nitrate distributions using high‐resolution synoptic in situ sensing along the lower Merced River (38 river km) in Central California (USA) from 2010 to 2012. We calibrated a distributed groundwater‐surface water (GW‐SW) discharge model for a conservative solute using 13 synoptic SC sampling events at flows ranging from 1.3 to 31.6 m3 s−1. Nitrogen loads ranged from 0.3 to 1.6 kg N d−1 and were greater following an extended high flow period during a wet winter. Applying the distributed GW‐SW discharge estimates to a simplistic reactive nitrate transport model, the model reproduced observed river nitrate distribution well (RRMSE = 5–21%), with dimensionless watershed‐averaged nitrate removal (kt) ranging from 0 to 0.43. Estimates were uncertain due to GW nitrate data variability, but the resulting range was consistent with prior removal estimates. At the segment scale, estimated GW‐SW nitrate loading ranged from 0 to 17 g
s−1 km−1. Local loading peaked near the middle of the study reach, a location that coincides with a shallow clay lens and with confined animal feed operations in close proximity to the river. Overall, the results demonstrate the potential for high‐resolution synoptic monitoring to support GW‐SW modeling efforts aimed at understanding and managing nonpoint source pollution.
Deconstructing the Effects of Flow on DOC, Nitrate, and Major Ion Interactions Using a High‐Frequency Aquatic Sensor Network
Authors: Koenig L. E. , Shattuck M. D. , Snyder L. E. , Potter J. D. , McDowell W. H. 
Published: October 2017

AbstractStreams provide a physical linkage between land and downstream river networks, delivering solutes derived from multiple catchment sources. We analyzed high‐frequency time series of stream solutes to characterize the timing and magnitude of major ion, nutrient, and organic matter transport over event, seasonal, and annual timescales as well as to assess whether nitrate (
) and dissolved organic carbon (DOC) transport are coupled in catchments, which would be expected if they are subject to similar biogeochemical controls throughout the watershed. Our data set includes in situ observations of
, fluorescent dissolved organic matter (DOC proxy), and specific conductance spanning 2–4 years in 10 streams and rivers across New Hampshire, including observations of nearly 700 individual hydrologic events. We found a positive response of
and DOC to flow in forested streams, but watershed development led to a negative relationship between
and discharge, and thus a decoupling of the overall
and DOC responses to flow. On event and seasonal timescales,
and DOC consistently displayed different behaviors. For example, in several streams, FDOM yield was greatest during summer storms while
yield was greatest during winter storms. Most streams had generalizable storm
and DOC responses, but differences in the timing of
and DOC transport suggest different catchment sources. Further, certain events, including rain‐on‐snow and summer storms following dry antecedent conditions, yielded disproportionate
responses. High‐frequency data allow for increased understanding of the processes controlling solute variability and will help reveal their responses to changing climatic regimes.