bluuebunny/crossref_metadata_2025_split huggingface dataset:
Time scales of the European surface air temperature variability: The role of the 7–8 year cycle
Authors: Jajcay Nikola , Hlinka Jaroslav , Kravtsov Sergey , Tsonis Anastasios A. , Paluš Milan 
Published: January 2016

AbstractAir temperature variability on different time scales exhibits recurring patterns and quasi‐oscillatory phenomena. Climate oscillations with the period about 7–8 years have been observed in many instrumental records in Europe. Although these oscillations are weak if considering their amplitude, they might have nonnegligible influence on temperature variability on shorter time scales due to cross‐scale interactions recently observed by Paluš (2014). In order to quantify the cross‐scale influence, we propose a simple conditional mean approach which estimates the effect of the cycle with the period close to 8 years on the amplitude of the annual cycle in surface air temperature (SAT) in the range 0.7–1.4°C and the effect on the overall variability of the SAT anomalies (SATA) leads to the changes 1.5–1.7°C in the annual SATA means. The strongest effect in the winter SATA means reaches 4–5°C in central European station and reanalysis data.
On the unique divergent response of the equatorial electrojet vertical polarization electric field to different solar flare events
Authors: Manju G. 
Published: January 2016

AbstractThe response of ionospheric E region to different flare events is investigated using coherent HF backscatter radar to bring out divergent observations. The study reveals the following aspects: (i) increase of absolute mean Doppler frequency by ~25–52% during the initial phase of the morning time flares of 9 September 2005 with concurrent fall in backscattered power and (ii) decrease of absolute mean Doppler frequency by ~11.6–16.2% during the initial phase of the flare of 20 February 2002 with concurrent fall in backscattered power. The Doppler frequency is directly related to vertical polarization electric field. Therefore, these observations are unique and in contrast to earlier works which have, in general, reported only a decrease in equatorial electrojet (EEJ) vertical polarization electric field during the initial phase of flare events. The present study also brings out the possible important role played by the height‐integrated conductivities in producing the divergent response of the EEJ. The large reduction in backscattered power for weak M class flare events is also observed in this study. In view of the importance of the ionosphere as a major source of error in GPS‐based navigation, the present result assumes significance.
Nonlinearity in chorus waves during a geomagnetic storm on 1 November 2012
Authors: Matsui H. , Paulson K. W. , Torbert R. B. , Spence H. E. , Kletzing C. A. , Kurth W. S. , Skoug R. M. , Larsen B. A. , Breneman A. W. 
Published: January 2016

AbstractIn this study, we investigate the possibility of nonlinearity in chorus waves during a geomagnetic storm on 1 November 2012. The data we use were measured by the Van Allen Probe B. Wave data and plasma sheet electron data are analyzed. Chorus waves were frequently measured in the morning side during the main phase of this storm. Large‐amplitude chorus waves were seen of the order of ∼0.6 nT and >7 mV/m, which are similar to or larger than the typical ULF waves. The waves quite often consist of rising tones during the burst sampling. Since the rising tone is known as a signature of nonlinearity, a large portion of the waves are regarded as nonlinear at least during the burst sampling periods. These results underline the importance of nonlinearity in the dynamics of chorus waves. We further compare the measurement and the nonlinear theories, based on the inhomogeneity ratio, our own calculation derived from the field equation and the backward wave oscillator model. The wave quantities examined are frequency, amplitude, frequency drift rate, and duration. This type of study is useful to more deeply understand wave‐particle interactions and hence may lead to predicting the generation and loss of radiation belt electrons in the future.
A wind‐driven, hybrid latent and sensible heat coastal polynya off Barrow, Alaska
Authors: Hirano Daisuke , Fukamachi Yasushi , Watanabe Eiji , Ohshima Kay I. , Iwamoto Katsushi , Mahoney Andrew R. , Eicken Hajo , Simizu Daisuke , Tamura Takeshi 
Published: January 2016

AbstractThe nature of the Barrow Coastal Polynya (BCP), which forms episodically off the Alaska coast in winter, is examined using mooring data, atmospheric reanalysis data, and satellite‐derived sea‐ice concentration and production data. We focus on oceanographic conditions such as water mass distribution and ocean current structure beneath the BCP. Two moorings were deployed off Barrow, Alaska in the northeastern Chukchi Sea from August 2009 to July 2010. For sea‐ice season from December to May, a characteristic sequence of five events associated with the BCP has been identified; (1) dominant northeasterly wind parallel to the Barrow Canyon, with an offshore component off Barrow, (2) high sea‐ice production, (3) upwelling of warm and saline Atlantic Water beneath the BCP, (4) strong up‐canyon shear flow associated with displaced density surfaces due to the upwelling, and (5) sudden suppression of ice growth. A baroclinic current structure, established after the upwelling, caused enhanced vertical shear and corresponding vertical mixing. The mixing event and open water formation occurred simultaneously, once sea‐ice production had stopped. Thus, mixing events accompanied by ocean heat flux from the upwelled warm water into the surface layer played an important role in formation/maintenance of the open water area (i.e., sensible heat polynya). The transition from a latent to a sensible heat polynya is well reproduced by a high‐resolution pan‐Arctic ice‐ocean model. We propose that the BCP, previously considered to be a latent heat polynya, is a wind‐driven hybrid latent and sensible heat polynya, with both features caused by the same northeasterly wind.
Impacts of Noah model physics on catchment‐scale runoff simulations
Authors: Zheng Donghai , Van der Velde Rogier , Su Zhongbo , Wen Jun , Wang Xin , Booij Martijn J. , Hoekstra Arjen Y. , Lv Shihua , Zhang Yu , Ek Michael B. 
Published: January 2016

AbstractNoah model physics options validated for the source region of the Yellow River (SRYR) are applied to investigate their ability in reproducing runoff at the catchment scale. Three sets of augmentations are implemented affecting descriptions of (i) turbulent and soil heat transport (Noah‐H), (ii) soil water flow (Noah‐W), and (iii) frozen ground processes (Noah‐F). Five numerical experiments are designed with the three augmented versions, a control run with default model physics and a run with all augmentations (Noah‐A). Each experiment is set up with vegetation and soil parameters from Weather Research and Forecasting data set, soil organic matter content from China Soil Database, 0.1° atmospheric forcing data from Institute of Tibetan Plateau Research (Chinese Academy of Sciences), and initial equilibrium model states achieved using a single‐year recurrent spin‐up. In situ heat flux, soil temperature (Ts), and soil moisture (θ) profile measurements are available for point‐scale assessment, whereas monthly streamflow is utilized for the catchment‐scale evaluation. The comparison with point measurements shows that the augmentations invoked with Noah‐H resolve issues with the heat flux and Ts simulation and Noah‐W mitigates deficiencies in the θ simulation, while Noah‐A yields improvements for both simulated surface energy and water budgets. In contrast, Noah‐F has a minor effect. Also, at catchment scale, the best model performance is found for Noah‐A leading to a base flow‐dominated runoff regime, whereby the surface runoff contribution remains significant. This study highlights the need for a complete description of vertical heat and water exchanges to correctly simulate the runoff in the seasonally frozen and high‐altitude SRYR at the catchment scale.
Meltwater influences on deep stick‐slip icequakes near the base of the Greenland Ice Sheet
Authors: Roeoesli Claudia , Helmstetter Agnes , Walter Fabian , Kissling Edi 
Published: January 2016

AbstractWe detected over 11,000 stick‐slip icequakes near the base of the western margin of the Greenland Ice Sheet using a 17‐seismometer array. These icequakes have negative (i.e., very small) moment magnitudes and, according to similarities in their waveforms, group into over 100 distinct clusters distributed beneath our 3 × 3 km study area. Some clusters were active for several weeks, while others have burst‐like episodes lasting 1–6 days only. Some clusters correlate with subglacial water pressure measured within a nearby moulin. For these clusters, we observe high water pressure concurrent with many small yet numerous stick‐slip icequakes and periods of lower water pressures with larger, less frequent icequakes. These patterns might change over time and are not common to all clusters. We explain these observations that the stick‐slip icequakes are located at sticky spots at the interface of the ice sheet with the glacier bed that consists of basal till characterized by different connectivity to the subglacial drainage system. Because the till's frictional strength depends on its pore pressure, variations in subglacial water pressure can either weaken or strengthen the bed; this explains the variation in seismic moments and interevent times. Our results suggest that seismogenic stick‐slip motion is an integral part of the flow mechanism in the ablation zone in western Greenland, which is highly sensitive to the configuration of the local subglacial drainage system. Stick‐slip motion may therefore play a key role in the relationship between climate‐induced changes of surface runoff and ice sheet dynamics.
Impacts of chronic N input on the carbon and nitrogen storage of a postfire Mediterranean‐type shrubland
Authors: Vourlitis George L. , Hentz Cloe S. 
Published: January 2016

AbstractMediterranean‐type shrublands are subject to periodic fire and high levels of nitrogen (N) deposition, but little is known how chronic N deposition affects carbon (C) and N storage during succession. We conducted a long‐term experiment in Californian chaparral to test the hypothesis that chronic N enrichment would increase postfire C and N accumulation. The experimental layout consisted of a randomized design where four 10 × 10 m plots received 5 g N m−2annually since 2003 and four 10 × 10 m plots served as controls. Aboveground and belowground C and N pools and fluxes were measured seasonally (every 3 months) for a period of 10 years. Added N rapidly increased soil extractable N pools and decreased soil pH; however, total soil C and N storage were not affected. Added N plots initially had significantly lower C and N storage than control plots, presumably because of nutrient losses from leaching and/or higher belowground C allocation. However, rates of aboveground N and C storage became significantly higher in added N plots after 4–5 years of exposure, thus increasing fuel buildup, which has implications for future fire intensity. This recovering chaparral stand is not yet “N saturated” after 10 years of chronic N input. However, N leaching continues to be higher in added N plots, indicating that postfire chaparral stands in high‐N deposition areas can be important sources of N to groundwater/aquatic systems even if productivity is stimulated by N input.
Estimation of evaporation over the upper Blue Nile basin by combining observations from satellites and river flow gauges
Authors: Allam Mariam M. , Jain Figueroa Anjuli , McLaughlin Dennis B. , Eltahir Elfatih A. B. 
Published: January 2016

AbstractReliable estimates of regional evapotranspiration are necessary to improve water resources management and planning. However, direct measurements of evaporation are expensive and difficult to obtain. Some of the difficulties are illustrated in a comparison of several satellite‐based estimates of evapotranspiration for the Upper Blue Nile (UBN) basin in Ethiopia. These estimates disagree both temporally and spatially. All the available data products underestimate evapotranspiration leading to basin‐scale mass balance errors on the order of 35 percent of the mean annual rainfall. This paper presents a methodology that combines satellite observations of rainfall, terrestrial water storage as well as river‐flow gauge measurements to estimate actual evapotranspiration over the UBN basin. The estimates derived from these inputs are constrained using a one‐layer soil water balance and routing model. Our results describe physically consistent long‐term spatial and temporal distributions of key hydrologic variables, including rainfall, evapotranspiration, and river‐flow. We estimate an annual evapotranspiration over the UBN basin of about 2.55 mm per day. Spatial and temporal evapotranspiration trends are revealed by dividing the basin into smaller subbasins. The methodology described here is applicable to other basins with limited observational coverage that are facing similar future challenges of water scarcity and climate change.
Enhancing multiple‐point geostatistical modeling: 1. Graph theory and pattern adjustment
Authors: Tahmasebi Pejman , Sahimi Muhammad 
Published: January 2016

AbstractIn recent years, higher‐order geostatistical methods have been used for modeling of a wide variety of large‐scale porous media, such as groundwater aquifers and oil reservoirs. Their popularity stems from their ability to account for qualitative data and the great flexibility that they offer for conditioning the models to hard (quantitative) data, which endow them with the capability for generating realistic realizations of porous formations with very complex channels, as well as features that are mainly a barrier to fluid flow. One group of such models consists of pattern‐based methods that use a set of data points for generating stochastic realizations by which the large‐scale structure and highly‐connected features are reproduced accurately. The cross correlation‐based simulation (CCSIM) algorithm, proposed previously by the authors, is a member of this group that has been shown to be capable of simulating multimillion cell models in a matter of a few CPU seconds. The method is, however, sensitive to pattern's specifications, such as boundaries and the number of replicates. In this paper the original CCSIM algorithm is reconsidered and two significant improvements are proposed for accurately reproducing large‐scale patterns of heterogeneities in porous media. First, an effective boundary‐correction method based on the graph theory is presented by which one identifies the optimal cutting path/surface for removing the patchiness and discontinuities in the realization of a porous medium. Next, a new pattern adjustment method is proposed that automatically transfers the features in a pattern to one that seamlessly matches the surrounding patterns. The original CCSIM algorithm is then combined with the two methods and is tested using various complex two‐ and three‐dimensional examples. It should, however, be emphasized that the methods that we propose in this paper are applicable to other pattern‐based geostatistical simulation methods.
Enhancing multiple‐point geostatistical modeling: 2. Iterative simulation and multiple distance function
Authors: Tahmasebi Pejman , Sahimi Muhammad 
Published: January 2016

AbstractThis series addresses a fundamental issue in multiple‐point statistical (MPS) simulation for generation of realizations of large‐scale porous media. Past methods suffer from the fact that they generate discontinuities and patchiness in the realizations that, in turn, affect their flow and transport properties. Part I of this series addressed certain aspects of this fundamental issue, and proposed two ways of improving of one such MPS method, namely, the cross correlation‐based simulation (CCSIM) method that was proposed by the authors. In the present paper, a new algorithm is proposed to further improve the quality of the realizations. The method utilizes the realizations generated by the algorithm introduced in Part I, iteratively removes any possible remaining discontinuities in them, and addresses the problem with honoring hard (quantitative) data, using an error map. The map represents the differences between the patterns in the training image (TI) and the current iteration of a realization. The resulting iterative CCSIM—the iCCSIM algorithm—utilizes a random path and the error map to identify the locations in the current realization in the iteration process that need further “repairing;” that is, those locations at which discontinuities may still exist. The computational time of the new iterative algorithm is considerably lower than one in which every cell of the simulation grid is visited in order to repair the discontinuities. Furthermore, several efficient distance functions are introduced by which one extracts effectively key information from the TIs. To increase the quality of the realizations and extracting the maximum amount of information from the TIs, the distance functions can be used simultaneously. The performance of the iCCSIM algorithm is studied using very complex 2‐D and 3‐D examples, including those that are process‐based. Comparison is made between the quality and accuracy of the results with those generated by the original CCSIM algorithm, which demonstrates the superior performance of the iCCSIM.
Trading‐off tolerable risk with climate change adaptation costs in water supply systems
Authors: Borgomeo Edoardo , Mortazavi‐Naeini Mohammad , Hall Jim W. , O'Sullivan Michael J. , Watson Tim 
Published: January 2016

AbstractChoosing secure water resource management plans inevitably requires trade‐offs between risks (for a variety of stakeholders), costs, and other impacts. We have previously argued that water resources planning should focus upon metrics of risk of water restrictions, accompanied by extensive simulation and scenario‐based exploration of uncertainty. However, the results of optimization subject to risk constraints can be sensitive to the specification of tolerable risk, which may not be precisely or consistently defined by different stakeholders. In this paper, we recast the water resources planning problem as a multiobjective optimization problem to identify least cost schemes that satisfy a set of criteria for tolerable risk, where tolerable risk is defined in terms of the frequency of water use restrictions of different levels of severity. Our proposed method links a very large ensemble of climate model projections to a water resource system model and a multiobjective optimization algorithm to identify a Pareto optimal set of water resource management plans across a 25 years planning period. In a case study application to the London water supply system, we identify water resources management plans that, for a given financial cost, maximize performance with respect to one or more probabilistic criteria. This illustrates trade‐offs between financial costs of plans and risk, and between risk criteria for four different severities of water use restrictions. Graphical representation of alternative sequences of investments in the Pareto set helps to identify water management options for which there is a robust case for including them in the plan.
Fungal Pathogens of Humans
Authors: Mitchell Thomas G 
Published: January 2016

AbstractMost fungi that cause human infections are free‐living saprobes and only accidental pathogens. The most prevalent mycoses are caused by fungi that are either members of the normal human microbiota, such as species ofCandidaandMalassezia, or ubiquitous, exogenous fungi that are highly adapted for survival on the human host, such as species ofAspergillusandCryptococcus. This article will summarise the aetiology, risk factors and clinical manifestations of the most common mycoses. Strategies for their diagnoses include traditional methods of microscopy and culture, as well as the detection of fungal antigens and antifungal antibodies, fungal deoxyribonucleic acid and structural components. Because both infectious fungi and their human hosts are eukaryotes, they share many cellular processes and macromolecules. Consequently, it is difficult to identify targets for antifungal drugs that do not inflict collateral damage on the patients.Key ConceptsSuperficial and cutaneous mycoses are among the most common of all communicable diseases.Geophilic and zoophilic dermatophytes usually cause acute, inflammatory lesions that respond to topical treatment within weeks and rarely recur. Conversely, anthropophilic dermatophytes tend to cause relatively mild, chronic lesions that may require months or years of treatment and frequently relapse.Subcutaneous mycoses may be caused by dozens of environmental moulds associated with vegetation and soil. These fungi are usually acquired by contamination of minor wounds. The infections are generally chronic and rarely spread to deeper tissues.The endemic mycoses (coccidioidomycosis, histoplasmosis, blastomycosis and paracoccidioidomycosis) are caused by dimorphic environmental moulds and associated with distinct geographic regions.More than 90% of endemic mycoses are caused by inhaling airborne conidia, and, in immunocompetent persons, the infections are asymptomatic or self‐limited; however, latent, viable fungal cells may persist and subsequently reactivate to cause overt disease. Risk factors for the manifestation of disease include compromised cell‐mediated immunity, genetic predisposition and male gender.Opportunistic mycoses are caused by globally distributed fungi that are either members of the human microbiota or ubiquitous environmental fungi. These mycoses have the highest global mortality.Innate immune responses (e.g. neutrophils, monocytes) provide crucial protection from systemic candidiasis, invasive aspergillosis and mucormycosis.Most patients with HIV/AIDS develop mucosal candidiasis (e.g. thrush, oesophagitis). Those with CD4+counts less than 100 cells μL−1are at risk for invasive fungi, such asCryptococcus,Aspergillusand others.Effective treatment of invasive mycoses relies on rapid identification of the fungus, administration of the appropriate antifungal drug and management of any underlying disease or condition.