bluuebunny/crossref_metadata_2025_split huggingface dataset:
Internal Tide Dissipation at Topography: Triadic Resonant Instability Equatorward and Evanescent Waves Poleward of the Critical Latitude
Authors: Richet O. , Chomaz J.‐M. , Muller C. 
Published: May 2018

AbstractSeveral studies have shown the existence of a critical latitude where the dissipation of internal tides is strongly enhanced. Internal tides are internal waves generated by barotropic tidal currents impinging rough topography at the seafloor. Their dissipation and concomitant diapycnal mixing are believed to be important for water masses and the large‐scale ocean circulation. The purpose of this study is to clarify the physical processes at the origin of this strong latitudinal dependence of tidal energy dissipation. We find that different mechanisms are involved equatorward and poleward of the critical latitude. Triadic resonant instabilities are responsible for the dissipation of internal tides equatorward of the critical latitude. In particular, a dominant triad involving the primary internal tide and near‐inertial waves is key. At the critical latitude, the peak of energy dissipation is explained by both increased instability growth rates, and smaller scales of secondary waves thus more prone to break and dissipate their energy. Surprisingly, poleward of the critical latitude, the generation of evanescent waves appears to be crucial. Triadic instabilities have been widely studied, but the transfer of energy to evanescent waves has received comparatively little attention. Our work suggests that the nonlinear transfer of energy from the internal tide to evanescent waves (corresponding to the 2f‐pump mechanism described by Young et al., 2008, https://doi.org/10.1017/S0022112008001742) is an efficient mechanism to dissipate internal tide energy near and poleward of the critical latitude. The theoretical results are confirmed in idealized high‐resolution numerical simulations of a barotropic M2 tide impinging sinusoidal topography in a linearly stratified fluid.
Signatures of the 1976–1977 Regime Shift in the North Pacific Revealed by Statistical Analysis
Authors: Giamalaki K. , Beaulieu C. , Faranda D. , Henson S. A. , Josey S. A. , Martin A. P. 
Published: May 2018

AbstractRegime shifts are abrupt changes in an ecosystem that may propagate through multiple trophic levels and have pronounced effects on the biotic and abiotic environment, potentially resulting in ecosystem reorganization. There are multiple mechanisms that could cause such abrupt events including natural and anthropogenic factors. In the North Pacific, a major shift in the physics of the system, including a sudden increase in sea surface temperature, was reported in 1977 with a prominent biological response in the lower trophic levels and subsequent effects on the fisheries and economy of the region. Here we investigate the statistics of physical processes that could have triggered and maintained the late 1970s shift. The hypothesis of an extreme sea level pressure event abruptly changing the oceanic conditions in winter 1976–1977, which was maintained by long‐term changes in air‐sea interaction processes, is tested. Using dynamical proxies, we show the occurrence of an extreme atmospheric event, specifically a persistent Aleutian Low during winter 1976–1977, which constitutes a substantial part of the triggering mechanism of the regime shift. Subsequent sudden changes in the net heat flux occurred in the western North Pacific, particularly in the Kuroshio Extension region, which contributed to the maintenance of the new regime.
Estimating Integrated Water Vapor Trends From VLBI, GPS, and Numerical Weather Models: Sensitivity to Tropospheric Parameterization
Authors: Balidakis Kyriakos , Nilsson Tobias , Zus Florian , Glaser Susanne , Heinkelmann Robert , Deng Zhiguo , Schuh Harald 
Published: May 2018

AbstractIn this study, we estimate integrated water vapor (IWV) trends from very long baseline interferometry (VLBI) and global navigation satellite systems (GNSS) data analysis, as well as from numerical weather models (NWMs). We study the impact of modeling and parameterization of the tropospheric delay from VLBI on IWV trends. We address the impact of the meteorological data source utilized to model the hydrostatic delay and the thermal deformation of antennas, as well as the mapping functions employed to project zenith delays to arbitrary directions. To do so, we derive a new mapping function, called Potsdam mapping functions based on NWM data and a new empirical model, GFZ‐PT. GFZ‐PT differs from previous realizations as it describes diurnal and subdiurnal in addition to long‐wavelength variations, it provides harmonic functions of ray tracing‐derived gradients, and it features robustly estimated rates. We find that alternating the mapping functions in VLBI data analysis yields no statistically significant differences in the IWV rates, whereas alternating the meteorological data source distorts the trends significantly. Moreover, we explore methods to extract IWV given a NWM. The rigorously estimated IWV rates from the different VLBI setups, GNSS, and ERA‐Interim are intercompared, and a good agreement is found. We find a quite good agreement comparing ERA‐Interim to VLBI and GNSS, separately, at the level of 75%.
Current and Future Estimates of Wind Energy Potential Over Saudi Arabia
Authors: Chen Wanfang , Castruccio Stefano , Genton Marc G. , Crippa Paola 
Published: May 2018

AbstractSaudi Arabia has a long tradition of relying on fossil fuels for satisfying its energy demand. With the rising energy needs due to population growth and societal development, the nation is seeking other sources of energy, which include its largely underused wind resources. In this paper, we analyze the wind power potential in Saudi Arabia based on the MENA CORDEX (Middle East North Africa Coordinated Regional Climate Downscaling Experiment) model output. We investigate which climate settings and MENA CORDEX runs best capture the spatiotemporal patterns of reanalysis products, as assessed by multiple statistical metrics. Although there is a systematic negative bias in wind speed magnitudes for the five analyzed MENA CORDEX simulations, all runs are able to reproduce the seasonality and annual cycle of wind speed shown in the reanalysis data. The MENA CORDEX run with the highest skills is used to quantify the wind energy potential in Saudi Arabia in both current and future climates. Our analysis shows that a high wind energy potential exists over a vast area of western Saudi Arabia, particularly in the region between Medina and the Red Sea coast and during summer months. Based on model projections, the energy potential in these areas is likely to persist at least until the middle of the 21st century and thus may provide a valuable renewable source of energy.
Seasonal Evolution of the Subglacial Hydrologic System Modified by Supraglacial Lake Drainage in Western Greenland
Authors: Andrews Lauren C. , Hoffman Matthew J. , Neumann Thomas A. , Catania Ginny A. , Lüthi Martin P. , Hawley Robert L. , Schild Kristin M. , Ryser Claudia , Morriss Blaine F. 
Published: May 2018

AbstractThe impact of summer surface melt on Greenland Ice Sheet dynamics is modulated by the state of the subglacial hydrologic system. Studies of ice motion indicate that efficiency of the subglacial system increases over the melt season, decreasing the sensitivity of ice motion to surface melt inputs. However, the behavior of the subglacial hydrologic system is complex and some characteristics are still poorly constrained. Here we investigate the coevolution of subglacial hydrology and ice motion in the Pâkitsoq region of western Greenland during the 2011 melt season. We analyze measurements from 11 Global Positioning System stations, from which we derive ice velocity, longitudinal strain rates, and basal uplift, alongside observations of surface ablation and supraglacial lake drainages. We observe ice acceleration after the onset of local surface melting, followed by gradual ice deceleration, consistent with increasing subglacial efficiency. In the study area, supraglacial lake drainages cooccur with a change in regional strain rate patterns and ice deceleration, suggesting that lake drainages contribute to rapid subglacial reorganization. At lower ice surface elevations (below ~900 m above sea level), ice motion is correlated with both total basal uplift and its rate of change, while at higher elevations (~900–1,100 m above sea level), ice motion correlated only with the basal uplift rate. This pattern suggests that continued cavity growth or subglacial sediment dynamics may be important in the apparent increase in subglacial drainage efficiency at higher elevations in the ablation zone. Our results further suggest that transient subglacial behavior is important in the seasonal evolution of ice motion.
Urbanization Effect on Winter Haze in the Yangtze River Delta Region of China
Authors: Zhong Shi , Qian Yun , Sarangi Chandan , Zhao Chun , Leung Ruby , Wang Hailong , Yan Huiping , Yang Tao , Yang Ben 
Published: May 2018

AbstractThe impact of urbanization‐induced land‐cover change and increase in anthropogenic emissions on the air quality of the megacity cluster of the Yangtze River Delta is investigated using the WRF‐Chem model coupled with an urban canopy model at cloud‐resolving resolution. The urban land‐cover effect results in considerable reduction of near‐surface aerosol concentrations over urban regions and an increase in particle concentrations at higher altitudes over the surrounding rural areas. The urban heat island effect increases the lower atmospheric instability and vertical velocity, thus increasing the planetary boundary layer height and ventilation over the urban area, favoring the dispersion of pollutants from urbanized areas to their immediate vicinities. However, the urbanization‐induced increases in aerosol emissions outweigh that of land‐cover change, resulting in a net increase in surface particle concentrations by up to 50 μg m−3 and the occurrence of winter haze by more than 10 d season−1 in the Yangtze River Delta region.
Paleomagnetic Study on the Permian Rocks of the Indochina Block and Its Implications for Paleogeographic Configuration and Northward Drifting of Cathaysialand in the Paleo‐Tethys
Authors: Yan Yonggang , Huang Baochun , Zhang Donghai , Charusiri Punya , Veeravinantanakul Apivut 
Published: May 2018

AbstractThe drift of Gondwana‐derived blocks across the Tethys has remained unclear specifically because one of the largest components, Indochina, has remained unconstrained by paleomagnetism during the late Paleozoic, the interval comprising the first half of its journey towards the Eurasian landmass. Hence, we report a paleomagnetic study of Early‐Middle Permian limestones from central Thailand yielding a high‐quality data set for the Indochina Block with probable primary origin. The magnetization yields a paleomagnetic pole at 34.1°N, 331.7°E (K = 45.4, A95 = 5.7°) corresponding to a paleolatitude of 21.2 ± 5.7°S at the center of the study area (15°N, 101°E) and supporting a tropical restoration for late Paleozoic Indochina. A total of ~5,000 km northward transition from a proximity to Gondwana in the Early‐Middle Permian (ca. 280 Ma) to the southern margin of Eurasia by the Late Triassic (Norian, ca. 220 Ma) is identified and yields an average northward latitudinal drift rate of ~4.5 cm/year. A concurrent northward drifting history during the Permian is suggested for the Indochina, North Qiangtang, and South China blocks, and thus, the widely used model of Permian Cathaysialand is quantitively supported when combined with their paleobiogeographic affinities.
Estimation of Lateral DOC Transport in Marginal Sea Based on Remote Sensing and Numerical Simulation
Authors: Cui Qianfang , He Xianqiang , Liu Qiong , Bai Yan , Chen Chen‐Tung Arthur , Chen Xiaoyan , Pan Delu 
Published: May 2018

AbstractDue to high temporal and spatial dynamics and complex biological processes, it is difficult to estimate lateral transportations of the dissolved organic carbon (DOC) in marginal seas by conventional field observations and model simulations. Taking the East China Sea (ECS), for example, this study proposed a novel model for estimating the lateral DOC flux in marginal sea. Three‐dimensional distributions of DOC concentrations were retrieved by satellite remote sensing. Furthermore, three‐dimensional currents were simulated using the numerical model. Finally, the lateral DOC flux in the whole ECS was estimated based on the satellite‐derived DOC concentrations and the simulated currents. The results showed that despite seasonal variations, the unit area lateral DOC flux remained high throughout the year in the Changjiang River estuary, Zhejiang‐Fujian Coast, Taiwan Strait, and Kuroshio regions. There were three eastward transportation channels which were strong in summer half year and weak in winter half year. Moreover, a northward transport zone extending from north of Taiwan to the south of the Changjiang River estuary was detected. In terms of annually net flux, highest net DOC import (30.65 TgC yr−1) was from the Taiwan Strait, mainly through the eastern side of the strait. The second highest net DOC import (18.75 TgC yr−1) was from the shelf slope (200 m isobath), mainly through the south part of the slope between 26°N and 26.5°N. Most of the net DOC export (−52.75 TgC yr−1) from the ECS was observed through the northern boundary (32°N), particularly in the outer shelf with water depth of 100–200 m.
Relating Anomaly Correlation to Lead Time: Principal Component Analysis of NMME Forecasts of Summer Precipitation in China
Authors: Zhao Tongtiegang , Chen Xiaohong , Liu Pan , Zhang Yongyong , Liu Bingjun , Lin Kairong 
Published: May 2018

AbstractThe skill of global climate model (GCM) forecasts is usually indicated by the anomaly correlation between ensemble mean and observation. For GCM forecasts, anomaly correlation does not steadily improve with decreasing lead time but oscillates instead. This paper aims to address the oscillation and illustrate the relationship between anomaly correlation and lead time. We formulate the anomaly correlation of forecasts at different initialization times as a vector and pool anomaly correlation vectors across grid cells in the analysis. We propose two patterns to characterize the spatial and temporal variation of anomaly correlation in the three‐dimensional space of latitude, longitude, and initialization time. The first pattern suggests that the anomaly correlation at different initialization times is at a similar level. The second pattern indicates that the anomaly correlation linearly increases with decreasing lead time. These two patterns are tested using the eigenvectors through principal component analysis. They are first illustrated using the GFDL‐CM2p1‐aer04 forecasts of summer precipitation in China. They are further verified by another nine sets of North‐American Multi‐Model Ensemble (NMME) forecasts. Overall, the first pattern explains more variation than the second pattern. In total, the two patterns explain 42% of the variation of anomaly correlation for CanCM3, 59% for CanCM4, 42% for COLA‐RSMAS‐CCSM3), 45% for COLA‐RSMAS‐CCSM4, 59% for GFDL‐CM2p1, 67% for GFDL‐CM2p1‐aer04, 65% for GFDL‐CM2p5‐FLOR‐A06, 57% for GFDL‐CM2p5‐FLOR‐B01, 48% for NCAR‐CESM1, and 60% for NCEP‐CFSv2. The percentage of explained variation demonstrates the effectiveness of the two patterns as exploratory tools to analyze the predictive performance of GCM forecasts.
Geological Characteristics of Von Kármán Crater, Northwestern South Pole‐Aitken Basin: Chang'E‐4 Landing Site Region
Authors: Huang Jun , Xiao Zhiyong , Flahaut Jessica , Martinot Mélissa , Head James , Xiao Xiao , Xie Minggang , Xiao Long 
Published: May 2018

AbstractVon Kármán crater (diameter = ~186 km), lying in the northwestern South Pole‐Aitken (SPA) basin, was formed in the pre‐Nectarian. The Von Kármán crater floor was subsequently flooded with one or several generations of mare basalts during the Imbrian period. Numerous subsequent impact craters in the surrounding region delivered ejecta to the floor, together forming a rich sample of the SPA basin and farside geologic history. We studied in details the targeted landing region (45.0–46.0°S, 176.4–178.8°E) of the 2018 Chinese lunar mission Chang'E‐4, within the Von Kármán crater. The topography of the landing region is generally flat at a baseline of ~60 m. Secondary craters and ejecta materials have covered most of the mare unit and can be traced back to at least four source craters (Finsen, Von Kármán L, Von Kármán L', and Antoniadi) based on preferential spatial orientations and crosscutting relationships. Extensive sinuous ridges and troughs are identified spatially related to Ba Jie crater (diameter = ~4 km). Reflectance spectral variations due to difference in both composition and physical properties are observed among the ejecta from various‐sized craters on the mare unit. The composition trends were used together with crater scaling relationships and estimates of regolith thickness to reconstruct the subsurface stratigraphy. The results reveal a complex geological history of the landing region and set the framework for the in situ measurements of the CE‐4 mission, which will provide unique insights into the compositions of farside mare basalt, SPA compositional zone including SPA compositional anomaly and Mg‐pyroxene annulus, regolith evolution, and the lunar space environment.
A high-fat diet stimulates fibroblast growth factor 23 formation in mice through TNFα upregulation
Authors: Glosse Philipp , Fajol Abul , Hirche Frank , Feger Martina , Voelkl Jakob , Lang Florian , Stangl Gabriele I. , Föller Michael 
Published: May 2018

Abstract
Background/objectives
Bone-derived fibroblast growth factor 23 (FGF23) is a hormone that suppresses renal phosphate reabsorption and calcitriol (i.e., 1,25(OH)2D3) formation together with its co-receptor Klotho. FGF23- or Klotho-deficient mice suffer from rapid aging with multiple age-associated diseases, at least in part due to massive calcification. FGF23 is considered as a disease biomarker since elevated plasma levels are observed early in patients with acute and chronic disorders including renal, cardiovascular, inflammatory, and metabolic diseases. An energy-dense diet, which induces sequelae of the metabolic syndrome in humans and mice at least in part by enhancing pro-inflammatory TNFα formation, has recently been demonstrated to stimulate FGF23 production.

Methods
We investigated the relevance of TNFα for high-fat diet (HFD)-induced FGF23 formation in wild-type (tnf+/+) and TNFα-deficient (tnf−/−) mice.

Results
Within 3 weeks, HFD feeding resulted in a strong increase in the serum FGF23 level in tnf+/+ mice. Moreover, it caused low-grade inflammation as evident from a surge in hepatic Tnfα transcript levels. TNFα stimulated Fgf23 transcription in UMR106 osteoblast-like cells. Serum FGF23 was significantly lower in tnf−/− mice compared to tnf+/+ mice following HFD. Serum phosphate and calcitriol were not significantly affected by genotype or diet.

Conclusions
We show that HFD feeding is a powerful stimulator of murine FGF23 production through TNFα formation.
Altered plasma arginine metabolome precedes behavioural and brain arginine metabolomic profile changes in the APPswe/PS1ΔE9 mouse model of Alzheimer’s disease
Authors: Bergin DH , Jing Y , Mockett BG , Zhang H , Abraham WC , Liu P 
Published: May 2018

AbstractWhile amyloid-beta (Aβ) peptides play a central role in the development of Alzheimer’s disease (AD), recent evidence also implicates altered metabolism of L-arginine in the pathogenesis of AD. The present study systematically investigated how behavioural function and the brain and plasma arginine metabolic profiles changed in a chronic Aβ accumulation model using male APPswe/PS1ΔE9 transgenic (Tg) mice at 7 and 13 months of age. As compared to their wild-type (WT) littermates, Tg mice displayed age-related deficits in spatial water maze tasks and alterations in brain arginine metabolism. Interestingly, the plasma arginine metabolic profile was markedly altered in 7-month Tg mice prior to major behavioural impairment. Receiver operating characteristic curve analysis revealed that plasma putrescine and spermine significantly differentiated between Tg and WT mice. These results demonstrate the parallel development of altered brain arginine metabolism and behavioural deficits in Tg mice. The altered plasma arginine metabolic profile that preceded the behavioural and brain profile changes suggests that there may be merit in an arginine-centric set of ante-mortem biomarkers for AD.
Glutamate and GABA in autism spectrum disorder—a translational magnetic resonance spectroscopy study in man and rodent models
Authors: Horder Jamie , Petrinovic Marija M. , Mendez Maria A. , Bruns Andreas , Takumi Toru , Spooren Will , Barker Gareth J. , Künnecke Basil , Murphy Declan G. 
Published: May 2018

AbstractAutism spectrum disorder (ASD) is a pervasive neurodevelopmental syndrome with a high human and economic burden. The pathophysiology of ASD is largely unclear, thus hampering development of pharmacological treatments for the core symptoms of the disorder. Abnormalities in glutamate and GABA signaling have been hypothesized to underlie ASD symptoms, and may form a therapeutic target, but it is not known whether these abnormalities are recapitulated in humans with ASD, as well as in rodent models of the disorder. We used translational proton magnetic resonance spectroscopy ([1H]MRS) to compare glutamate and GABA levels in adult humans with ASD and in a panel of six diverse rodent ASD models, encompassing genetic and environmental etiologies. [1H]MRS was performed in the striatum and the medial prefrontal cortex, of the humans, mice, and rats in order to allow for direct cross-species comparisons in specific cortical and subcortical brain regions implicated in ASD. In humans with ASD, glutamate concentration was reduced in the striatum and this was correlated with the severity of social symptoms. GABA levels were not altered in either brain region. The reduction in striatal glutamate was recapitulated in mice prenatally exposed to valproate, and in mice and rats carrying Nlgn3 mutations, but not in rodent ASD models with other etiologies. Our findings suggest that glutamate/GABA abnormalities in the corticostriatal circuitry may be a key pathological mechanism in ASD; and may be linked to alterations in the neuroligin–neurexin signaling complex.