bluuebunny/crossref_metadata_2025_split huggingface dataset:
Changes to the Water Balance Over a Century of Urban Development in Two Neighborhoods: Vancouver, Canada
Authors: Kokkonen T. V. , Grimmond C. S. B. , Christen A. , Oke T. R. , Järvi L. 
Published: August 2018

AbstractHydrological cycles of two suburban neighborhoods in Vancouver, BC, during initial urban development and subsequent urban densification (1920–2010) are examined using the Surface Urban Energy and Water Balance Scheme. The two neighborhoods have different surface characteristics (as determined from aerial photographs) which impact the hydrological processes. Unlike previous studies of the effect of urbanization on the local hydrology, densification of already built lots is explored with a focus on the neighborhood scale. Human behavioral changes to irrigation are accounted for in the simulations. Irrigation is the dominant factor, accounting for up to 56% of the water input on an annual basis in the study areas. This may surpass garden needs and go to runoff. Irrigating once a week would provide sufficient water for the garden. Without irrigation, evaporation would have decreased over the 91 years at a rate of up to 1.4 mm/year and runoff increased at 4.0 mm/year with the increase in impervious cover. Similarly without irrigation, the ratio of sensible heat flux to the available energy would have increased over the 91 years at a rate of up to 0.003 per year. Urbanization and densification cause an increase in runoff and increase risk of surface flooding. Small daily runoff events with short return periods have increased over the century, whereas the occurrence of heavy daily runoff events (return period > 52 days) are not affected. The results can help us to understand the dominant factors in the suburban hydrological cycle and can inform urban planning.
U‐PB Detrital Zircon Geochronology of the Lower Danube and Its Tributaries: Implications for the Geology of the Carpathians
Authors: Ducea Mihai N. , Giosan Liviu , Carter Andrew , Balica Constantin , Stoica Adriana M. , Roban Relu D. , Balintoni Ion , Filip Florin , Petrescu Lucian 
Published: August 2018

AbstractWe performed a detrital zircon (DZ) U‐Pb geochronologic survey of the lower parts of the Danube River approaching its Danube delta, Black Sea sink, and a few large tributaries (Tisza, Jiu, Olt, and Siret) originating in the nearby Carpathian Mountains. Samples are modern sediments. DZ age spectra reflect the geology and specifically the crustal age formation of the source area, which in this case is primarily the Romanian Carpathians and their foreland with contributions from the Balkan Mountains to the south of Danube and the East European Craton. The zircon cargo of these rivers suggests a source area that formed during the latest Proterozoic and mostly into the Cambrian and Ordovician as island arcs and back‐arc basins in a Peri‐Gondwanan subduction setting (~600–440 Ma). The Inner Carpathian units are dominated by a U‐Pb DZ peak in the Ordovician (460–470 Ma) and little inheritance from the nearby continental masses, whereas the Outer Carpathian units and the foreland have two main peaks, one Ediacaran (570–610 Ma) and one in the earliest Permian (290–300 Ma), corresponding to granitic rocks known regionally. A prominent igneous Variscan peak (320–350 Ma) in the Danube's and tributaries DZ zircon record is difficult to explain and points out to either an extra Carpathian source or major unknown gaps in our understanding of Carpathian geology. Younger peaks corresponding to arc magmatism during the Alpine period make up as much as about 10% of the DZ archive, consistent with the magnitude and surface exposure of Mesozoic and Cenozoic arcs.
Local Excitation of Whistler Mode Waves and Associated Langmuir Waves at Dayside Reconnection Regions
Authors: Li Jinxing , Bortnik Jacob , An Xin , Li Wen , Russell Christopher T. , Zhou Meng , Berchem Jean , Zhao Cong , Wang Shan , Torbert Roy B. , Le Contel Olivier , Ergun Robert E. , Lindqvist Per‐Arne , Pollock Craig J. , Burch James L. 
Published: August 2018

AbstractIn the Earth's dayside reconnection boundary layer, whistler mode waves coincide with magnetic field openings and the formation of the resultant anisotropic electrons. Depending on the energy range of anisotropic electrons, whistlers can grow at frequencies in the upper and/or lower band. Observations show that whistler mode waves modulate Langmuir wave amplitude as they propagate toward the X line. Observations of whistler mode wave phase and Langmuir waves packets, as well as coincident electron measurements, reveal that whistler mode waves can accelerate electrons via Landau resonance at locations where E||is antiparallel to the wave propagation direction. The accelerated electrons produce localized beams, which subsequently drive the periodically modulated Langmuir waves. The close association of those two wave modes reveals the microscale electron dynamics in the exhaust region, and the proposed mechanism could potentially be applied to explain the modulation events observed in planetary magnetospheres and in the solar wind.
Reversal of the Direction of Horizontal Velocities Induced by GIA as a Function of Mantle Viscosity
Authors: Hermans T. H. J. , van der Wal W. , Broerse T. 
Published: August 2018

AbstractIn regions undergoing glacial isostatic adjustment present‐day horizontal surface motion is observed to point mostly, but not always, away from the former ice load. To interpret these observations, we investigate the direction of horizontal velocities using glacial isostatic adjustment models. The direction is controlled by the opposing actions of inward mantle flow and outward lithosphere motion. In contrast with the prevailing idea that glacial isostatic adjustment‐induced horizontal velocities point outward, we show that velocities can be either outward or inward. Immediately after deglaciation velocities point inward but change direction to outward after a time that is controlled by mantle viscosity. Present‐day horizontal velocities point outward for a uniform mantle viscosity below 1020 Pa s and inward for above 1022 Pa s, with a combination of outward and inward in between. Our results help to interpret GPS‐observed horizontal velocities in areas with varying mantle viscosity.
First Evidence of Persistent Nighttime Temperature Structures in the Neutral Thermosphere of Mars
Authors: Pilinski M. , Bougher S. , Greer K. , Thiemann E. , Andersson L. , Benna M. , Elrod M. 
Published: August 2018

AbstractUsing two Mars years of data collected by the Neutral Gas and Ion Mass Spectrometer on the Mars Atmosphere and Volatiles EvolutioN spacecraft, we reconstruct the local solar time structure of the Martian equatorial thermosphere for the dawn and dusk sectors. The results indicate the presence of several persistent features near the dusk and dawn terminators appearing in the neutral temperature and in the O, Ar, N2, and CO2 densities. The dusk temperature features include a minimum at the terminator surrounded by two local maxima with amplitudes between 20 and 40 K. A nighttime temperature enhancement occurs at a local solar time of 4–5 hr and has an amplitude between 50 and 100 K relative to the surrounding temperatures. The observed enhancements are interpreted to be a result of either nighttime dynamical heating caused by converging and downwelling winds or of a terminator wave originating in the lower atmosphere.
Spatial Heterogeneity of the Temporal Dynamics of Arctic Tundra Vegetation
Authors: Reichle L. M. , Epstein H. E. , Bhatt U. S. , Raynolds M. K. , Walker D. A. 
Published: August 2018

AbstractArctic tundra vegetation has largely been “greening” in recent decades, resulting in major changes to terrestrial ecosystems, with implications for surface energy balance, permafrost, carbon and water cycling, herbivore populations, and human land use. While general greening trends have been well‐studied, more specific vegetation‐temperature dynamics are spatially and temporally heterogeneous and currently not well understood. This study uses Normalized Difference Vegetation Index (NDVI) and Summer Warmth Index (SWI) data to investigate patterns of arctic tundra vegetation and temperature dynamics over North American and Eurasian continents and by Arctic bioclimate subzones (essentially latitudinal‐based). Relative vegetation increases in northern subzones were muted compared to temperature increases, whereas relative vegetation increases in southern subzones were consistent with, or greater than, relative temperature changes. Detrended, interannual NDVI variances were greatest in middle and southern subzones, whereas interannual SWI variances were greatest in southern subzones. Annual SWI and NDVI relationships were strongest in midlatitude subzones.
Response of Banded Whistler Mode Waves to the Enhancement of Solar Wind Dynamic Pressure in the Inner Earth's Magnetosphere
Authors: Yu Xiongdong , Yuan Zhigang , Li Haimeng , Huang Shiyong , Wang Dedong , Yao Fei , Funsten H. O. , Wygant J. R. 
Published: August 2018

AbstractWith observations of Van Allen Probe A, in this letter we display a typical event where banded whistler waves shifted up their frequencies with frequency bands broadening as a response to the enhancement of solar wind dynamic pressure. Meanwhile, the anisotropy of electrons with energies about several tens of keV was observed to increase. Through the comparison of the calculated wave growth rates and observed wave spectral intensity, we suggest that those banded whistler waves observed with frequencies shifted up and frequency bands broadening could be locally excited by these hot electrons with increased anisotropy. The current study provides a great in situ evidence for the influence on frequencies of banded whistler waves by the enhancement of solar wind dynamic pressures, which reveals the important role of solar wind dynamic pressures playing in the frequency properties of banded whistler waves.
Energy Conversion Reveals Regime Transition of Imbibition in a Rough Fracture
Authors: Hu Ran , Wu Dong‐Sheng , Yang Zhibing , Chen Yi‐Feng 
Published: August 2018

AbstractAs externally imposed flow rate increases during imbibition, viscous force increasingly dominates displacement over capillarity and imbibition shifts from capillary to capillary‐viscous regimes. Previous studies focused on capillary regime, lacking a fundamental understanding of regime transition. Here we study the imbibition transition via flow rate‐controlled experiments in a rough fracture. By analyzing energy balance in multiphase flow system, we find a fundamental link between regime transition and energy conversion. In capillary regime, surface energy is partially transformed into external work and an amount of 51−58% is dissipated via local rapid, irreversible events; while in capillary‐viscous regime, surface energy together with external work is transformed into kinetic and dissipated energies. This transition, corresponding to critical capillary number, is evidenced by quantitative analysis of invasion morphologies. Our work bridges the gap between energy conversion/dissipation and multiphase flow and has important implications for identifying imbibition regimes in enhanced oil recovery and geological CO2 sequestration.
Western Pacific Oceanic Heat Content: A Better Predictor of La Niña Than of El Niño
Authors: Planton Yann , Vialard Jérôme , Guilyardi Eric , Lengaigne Matthieu , Izumo Takeshi 
Published: August 2018

AbstractThe western equatorial Pacific oceanic heat content (warm water volume in the west or WWVw) is the best El Niño–Southern Oscillation (ENSO) predictor beyond 1‐year lead. Using observations and selected Coupled Model Intercomparison Project Phase 5 simulations, we show that a discharged WWVw in boreal fall is a better predictor of La Niña than a recharged WWVw for El Niño 13 months later, both in terms of occurrence and amplitude. These results are robust when considering the heat content across the entire equatorial Pacific (WWV) at shorter lead times, including all Coupled Model Intercomparison Project Phase 5 models or excluding Niño‐Niña and Niña‐Niño phase transitions. Suggested mechanisms for this asymmetry include (1) the negatively skewed WWVw distribution with stronger discharges related to stronger wind stress anomalies during El Niño and (2) the stronger positive Bjerknes feedback loop during El Niño. The possible role of stronger subseasonal wind variations during El Niño is also discussed.
A Comparison of Quiet Time Thermospheric Winds Between FPI Observations and Model Calculations
Authors: Jiang Guoying , Xu Jiyao , Wang Wenbin , Yuan Wei , Zhang Shunrong , Yu Tao , Zhang Xiaoxin , Huang Cong , Kerr Robert B. , Noto John , Li Jingyuan , Liu Weijun , Li Qinzeng 
Published: August 2018

AbstractWe investigate local time, seasonal, and longitudinal variations of thermospheric horizontal winds at midlatitudes during geomagnetically quiet times by comparing winds from observations, an empirical wind model, and a numerical model. The observations are from three Fabry‐Perot interferometers (FPIs), the empirical model is the most recent version of the Horizontal Wind Model 14 (HWM14), and the numerical model is the Thermosphere‐Ionosphere‐Electrodynamics General Circulation Model of the National Center for Atmospheric Research. The three FPI stations are located at Xinglong (geographically 40.2°N, 117.4°E; geomagnetically 35°N) and Kelan (geographically 38.7°N, 111.6°E; geomagnetically 34°N) in China and at Millstone Hill (geographically 42.6°N, 71.5°W; geomagnetically 52°N) in United States. The results show that the winds at Millstone Hill are more southward and more westward than those at Xinglong and Kelan in all seasons; the directional reversal time of zonal winds is also earlier at Millstone Hill than at the other two stations. Thermosphere‐Ionosphere‐Electrodynamics General Circulation Model shows better agreement with FPI observations in the winter months compared to summer, and in general best replicates those measurements taken at Millstone Hill. HWM14 generally produces agreement with quiet time midlatitude neutral wind measurements, with HWM14 meridional winds comparing very well throughout most of a year. HWM14 model‐data discrepancies occur mainly in the zonal winds during the winter season. Overall, HWM14 predicts MH FPI observations slightly better than it does for the data from the two Asian stations.
Polar Ion Temperature Variations During the 22 January 2012 Magnetic Storm
Authors: Horvath Ildiko , Lovell Brian C. 
Published: August 2018

AbstractWe study the 22 January 2012 magnetic storm, during which some localized neutral density (DN) increases developed, and its polar ion temperature (Ti) variations in terms of the earthward Poynting flux (S||) deposited into the coupled ionosphere‐thermosphere system. We investigate the storm's nature, some flow channel events that are the ionospheric signatures of flux transfer events triggered by magnetic reconnections, and the resultant thermospheric responses. We utilize solar and interplanetary magnetic field data and multi‐instrument topside ionospheric and thermospheric measurements. Results reveal the presence of antisunward propagating solar wind Alfven waves during the various storm phases triggering flux transfer events/flow channel events and launching atmospheric gravity waves whose Ti signatures appeared as episodic Ti variations. Various scenarios demonstrate the direct correlation between S|| and DN and the irregular Ti responses within/above flow channels that we explain in terms of frictional heating (Tfrc). We identify Ti responses during various flow channel events as (1) direct/intermittent and (2) opposite, with S|| and DN reflecting the respective underlying flow channel development at the time of detection as (1) early stage when Tfrc was high due to the still large velocity differences between ions and neutrals and as (2) late stage when Tfrc ceased since ions and neutrals moved together. Ti oscillations are observed to be originating from polar or auroral flow channels and propagating across the polar cap toward the equator. We conclude that antisunward solar wind Alfven waves had a significant impact on Ti variability during this storm by modulating magnetic reconnection and launching atmospheric gravity waves.
Recurring Slow Slip Events and Earthquake Nucleation in the Source Region of the M 7 Ibaraki‐Oki Earthquakes Revealed by Earthquake Swarm and Foreshock Activity
Authors: Nishikawa Tomoaki , Ide Satoshi 
Published: August 2018

AbstractSlow slip events (SSEs) on the plate interface are closely related to the occurrence of earthquakes and often trigger earthquake swarms in subduction zones. Moreover, some SSEs, accompanied by intensive foreshocks, precede large interplate earthquakes. Therefore, detecting and monitoring SSEs is important for assessing the potential of future large earthquakes. However, there are many SSEs not followed by large earthquakes, and it is unclear whether these can be distinguished from SSEs preceding large earthquakes. Here we use the epidemic‐type aftershock sequence (ETAS) model and matched‐filter technique to examine the spatial‐temporal distribution of earthquake swarms and foreshocks at Ibaraki‐Oki in the Japan Trench. We found that 19 swarm sequences repeatedly occurred during the period 1982–2008 at the same location as the foreshock sequences of the 1982 and 2008 M 7 Ibaraki‐Oki earthquakes. Both the foreshock and swarm sequences contain repeating earthquakes and have anomalously high seismicity rates inexplicable by the ETAS model, suggesting the recurrence of SSEs. The foreshock sequences in 1982 and 2008 contain more events inexplicable by the ETAS model than the swarm sequences. The fault slip of repeating earthquakes in the 2008 foreshock sequence was also larger than those of the swarm sequences, and the slip rate showed an abrupt increase 12 hr before the 2008 M 7 event. Our results imply that the SSEs that preceded the M 7 events had larger seismic moments than the other SSEs. These large SSEs might be related to the nucleation phase of the M 7 earthquakes.
Estimating Hypoxic Volume in the Chesapeake Bay Using Two Continuously Sampled Oxygen Profiles
Authors: Bever Aaron J. , Friedrichs Marjorie A. M. , Friedrichs Carl T. , Scully Malcolm E. 
Published: August 2018

AbstractLow levels of dissolved oxygen (DO) occur in many embayments throughout the world and have numerous detrimental effects on biota. Although measurement of in situ DO is straightforward with modern instrumentation, quantifying the volume of water in a given embayment that is hypoxic (hypoxic volume (HV)) is a more difficult task; however, this information is critical for determining whether management efforts to increase DO are having an overall impact. This paper uses output from a three‐dimensional numerical model to demonstrate that HV in Chesapeake Bay can be estimated well with as few as two vertical profiles. In addition, the cumulative hypoxic volume (HVC; the total amount of hypoxia in a given year) can be calculated with relatively low uncertainty (<10%) if continuous DO data are available from two strategically positioned vertical profiles. This is because HV in the Chesapeake Bay is strongly constrained by the geometry of the embayment. A simple Geometric HV calculation method is presented and numerical model results are used to illustrate that for calculating HVC, the results using two daily‐averaged profiles are typically more accurate than those of the standard method that interpolates bimonthly cruise data. Bimonthly data produce less accurate estimates of HVC because high‐frequency changes in oxygen concentration, for example, due to regional‐weather‐ or storm‐induced changes in wind direction and magnitude, are not resolved. The advantages of supplementing cruise‐based sampling with continuous vertical profiles to estimate HVC should be applicable to other systems where hypoxic water is constrained to a specific area by bathymetry.
Thank You to Our 2017 Peer Reviewers
Authors: Brewer Peter , Chambers Don , Hetland Robert , Karnauskas Kristopher , Lowe Ryan , Moran S. Bradley , Oey Lie‐Yauw , Pinardi Nadia , Proshutinsky Andrey 
Published: August 2018

AbstractSimilar to the construction of physical ships and laboratory buildings, scientific knowledge is built incrementally and requires solid components of data, theory, and methodology at each phase of the “construction.” The peer‐review process provides the necessary “inspection” and the assurance that every step of the construction is solid, particularly in regard to the proper use of the scientific method. The peer‐review process helps improve the published work by providing constructive suggestions and by safeguarding against scientific work that could later be found to be built on shaky foundations. Because no single scientist has intimate knowledge of today's many aspects of the Ocean Sciences, we rely on each other's expertise to serve as unbiased “inspectors” of published articles. Your considerable time and effort, spent reviewing JGR‐Oceans manuscript(s) during 2017, are sincerely appreciated by our editorial board and by the Ocean Science community at large. We thank you for rising to this professional challenge and for your wisdom, commitment, skill, and service.
Modeling Regional Pollution Transport Events During KORUS‐AQ: Progress and Challenges in Improving Representation of Land‐Atmosphere Feedbacks
Authors: Huang Min , Crawford James H. , Diskin Glenn S. , Santanello Joseph A. , Kumar Sujay V. , Pusede Sally E. , Parrington Mark , Carmichael Gregory R. 
Published: August 2018

AbstractThis study evaluates the impact of assimilating soil moisture data from National Aeronautics and Space Administration (NASA)'s Soil Moisture Active Passive (SMAP) on short‐term regional weather and air quality modeling in East Asia during the Korea‐U.S. Air Quality Study (KORUS‐AQ) airborne campaign. SMAP data are assimilated into the Noah land surface model using an ensemble Kalman filter approach in the Land Information System framework, which is semicoupled with the NASA‐Unified Weather Research and Forecasting model with online chemistry (NUWRF‐Chem). With SMAP assimilation included, water vapor and carbon monoxide (CO) transport from northern central China transitional climate zones to South Korea is better represented in NUWRF‐Chem during two studied pollution events. Influenced by different synoptic conditions and emission patterns, impact of SMAP assimilation on modeled CO in South Korea is intense (>30 ppbv) during one event and less significant (<8 ppbv) during the other. SMAP assimilation impact on air quality modeling skill is complicated by other error sources such as the chemical initial and boundary conditions (IC/LBC) and emission inputs of NUWRF‐Chem. Using a satellite‐observation‐constrained chemical IC/LBC instead of a free‐running, coarser‐resolution chemical IC/LBC reduces modeled CO by up to 80 ppbv over South Korea. Consequently, CO performance is improved in the middle‐upper troposphere whereas degraded in the lower troposphere. Remaining negative CO biases result largely from the emissions inputs. The advancements in land surface modeling and chemical IC/LBC presented here are expected to benefit future investigations on constraining emissions using observations, which can in turn enable more accurate assessments of SMAP assimilation and chemical IC/LBC impacts.