bluuebunny/crossref_metadata_2025 huggingface dataset:
Ethics in the Age of Technological Change and its Impact on the Professional Identity of Librarians
Authors: Hicks Deborah
Published: March 2015

Professional ethics and core values provide professionals with guidance for their actions by helping professionals determine what constitutes right and wrong professional action. Because they are written for and by librarians, these documents offer one articulation of librarians' professional identities. This chapter examines the core values of librarianship with an eye to how they articulate the relationship librarians have with technology. These documents illustrate that librarians understand technology to be a tool that is used to meet the information needs of users. The Social Construction Of Technology (SCOT) is discussed as an alternative approach to the understanding of technology by LIS professionals. SCOT examines the social processes that are behind the development of technologies and highlights how different social groups contribute to the social meaning and even use of technology. SCOT provides an expanded view of ethics that encourages librarians to not only consider their professional ethics when implementing a new technology but also the intentions of the technology's developers, its various users, and their local communities. To illustrate the potential of SCOT for librarians, this chapter explores an examination of how librarians have managed the ethical challenges that Radio Frequency Identification (RFID) has brought to library services, followed by an examination of how librarians interpret their ethical role as service providers.
Dust aerosol radiative effects during summer 2012 simulated with a coupled regional aerosol–atmosphere–ocean model over the Mediterranean
Authors: Nabat P. , Somot S. , Mallet M. , Michou M. , Sevault F. , Driouech F. , Meloni D. , di Sarra A. , Di Biagio C. , Formenti P. , Sicard M. , Léon J.-F. , Bouin M.-N.
Published: March 2015

Abstract. The present study investigates the radiative effects of dust aerosols in the Mediterranean region during summer 2012 using a coupled regional aerosol–atmosphere–ocean model (CNRM-RCSM5). A prognostic aerosol scheme, including desert dust, sea salt, organic, black-carbon and sulphate particles, has been integrated to CNRM-RCSM5 in addition to the atmosphere, land surface and ocean components. An evaluation of this aerosol scheme of CNRM-RCSM5, and especially of the dust aerosols, has been performed against in situ and satellite measurements, showing its ability to reproduce the spatial and temporal variability of aerosol optical depth (AOD) over the Mediterranean region in summer 2012. The dust vertical and size distributions have also been evaluated against observations from the TRAQA/ChArMEx campaign. Three simulations have been carried out for summer 2012 with CNRM-RCSM5, including the full prognostic aerosol scheme, only monthly-averaged AOD means from the aerosol scheme or no aerosols at all, in order to focus on the radiative effects of dust particles and the role of the prognostic scheme. Surface short-wave aerosol radiative forcing variability is found to be more than twice as high over regions affected by dust aerosols, when using a prognostic aerosol scheme instead of monthly AOD means. In this case downward surface solar radiation is also found to be better reproduced according to a comparison with several stations across the Mediterranean. A composite study over 14 stations across the Mediterranean, designed to identify days with high dust AOD, also reveals the improvement of the representation of surface temperature brought by the use of the prognostic aerosol scheme. Indeed the surface receives less radiation during dusty days, but only the simulation using the prognostic aerosol scheme is found to reproduce the observed intensity of the dimming and warming on dusty days. Moreover, the radiation and temperature averages over summer 2012 are also modified by the use of prognostic aerosols, mainly because of the differences brought in short-wave aerosol radiative forcing variability. Therefore this first comparison over summer 2012 highlights the importance of the choice of the representation of aerosols in climate models.
Joint inference of misaligned irregular time series with application to Greenland ice core data
Authors: Doan T. K. , Haslett J. , Parnell A. C.
Published: March 2015

Abstract. Ice cores provide insight into the past climate over many millennia. Due to ice compaction, the raw data for any single core are irregular in time. Multiple cores have different irregularities; and when considered together, they are misaligned in time. After processing, such data are made available to researchers as regular time series: a data product. Typically, these cores are independently processed. This paper considers a fast Bayesian method for the joint processing of multiple irregular series. This is shown to be more efficient than the independent alternative. Furthermore, our explicit framework permits a reliable modelling of the impact of the multiple sources of uncertainty. The methodology is illustrated with the analysis of a pair of ice cores. Our data products, in the form of posterior marginals or joint distributions on an arbitrary temporal grid, are finite Gaussian mixtures. We can also produce process histories to study non-linear functionals of interest. More generally, the concept of joint analysis via hierarchical Gaussian process models can be widely extended, as the models used can be viewed within the larger context of continuous space–time processes.
Identifying water mass depletion in northern Iraq observed by GRACE
Authors: Mulder G. , Olsthoorn T. N. , Al-Manmi D. A. M. A. , Schrama E. J. O. , Smidt E. H.
Published: March 2015

Abstract. Observations acquired by Gravity Recovery And Climate Experiment (GRACE) mission indicate a mass loss of 146 ± 6 mm equivalent water height (EWH) in northern Iraq between 2007 and 2009. These data are used as an independent validation of lake mass variations and a rainfall-runoff model, which is based on local geology and climate conditions. Model inputs are precipitation from Tropical Rainfall Measurement Mission (TRMM) observations, and climatic parameters from Global Land Data Assimilation Systems (GLDAS) model parameters. The model is calibrated with observed river discharge and includes a representation of the karstified aquifers in the region to improve model realism. Lake mass variations were derived from Moderate Resolution Imaging Spectroradiometer (MODIS) in combination with satellite altimetry and some in situ data. Our rainfall–runoff model confirms that northern Iraq suffered a drought between 2007 and 2009 and captures the annual cycle and longer trend of the observed GRACE data. The total mass depletion seen by GRACE between 2007 and 2009 is mainly explained by a lake mass depletion of 75 ± 3 mm EWH and a natural groundwater depletion of 39 ± 8 mm EWH. Our findings indicate that anthropogenic groundwater extraction has a minor influence in this region, while a decline in lake mass and natural depletion of groundwater play a key role.
Large-scale numerical modeling of hydro-acoustic waves generated by tsunamigenic earthquakes
Authors: Cecioni C. , Abdolali A. , Bellotti G. , Sammarco P.
Published: March 2015

Abstract. Tsunamigenic fast movements of the seabed generate pressure waves in weakly compressible seawater, namely hydro-acoustic waves, which travel at the sound celerity in water (about 1500 m s−1). These waves travel much faster than the counterpart long free-surface gravity waves and contain significant information on the source. Measurement of hydro-acoustic waves can therefore anticipate the tsunami arrival and significantly improve the capability of tsunami early warning systems. In this paper a novel numerical model for reproduction of hydro-acoustic waves is applied to analyze the generation and propagation in real bathymetry of these pressure perturbations for two historical catastrophic earthquake scenarios in Mediterranean Sea. The model is based on the solution of a depth-integrated equation, and therefore results are computationally efficient in reconstructing the hydro-acoustic waves propagation scenarios.
Changes in Herdsmen's Pastoral Behaviour Triggered by Rangeland Degradation in the Source Region of the Yellow River, Qinghai-Tibetan Plateau
Authors: Chen Qiao , Lu Qingshui , Gao Zhiqiang
Published: March 2015

The Qinghai-Tibetan Plateau has experienced extensive degradation in recent years since the privatization of livestock and rangeland ownership and the resulting dynamic changes in stocking rates. Herdsmen have had to adapt their behaviour in order to maximize profit. This paper outlines those changes and the consequent impacts on the ecosystem. The results show that livestock death rates have continued to increase in line with the deterioration of rangeland. Although farms have increased the proportion of yak in their herds, the total number of livestock in Maduo county has decreased significantly from one million in 1977 to 0.42 million in 2003.
The AKIS Concept and its Relevance in Selected EU Member States
Authors: Knierim A. , Boenning K. , Caggiano M. , Cristóvão A. , Dirimanova V. , Koehnen T. , Labarthe P. , Prager K.
Published: March 2015

Recently, Agricultural Knowledge and Innovation Systems (AKISs) have gained considerable attention in scientific and political forums in the European Union (EU). AKIS is considered a key concept in identifying, analysing and assessing the various actors in the agricultural sector as well as their communication and interaction for innovation processes. Using qualitative expert interviews and organizational mapping, the features of national AKISs were investigated in selected EU member states (Belgium, France, Ireland, Germany, Portugal and the UK). The authors present the different national AKISs and compare them qualitatively with regard to their institutional settings, their overall policy frameworks and their coordinating structures. Conclusions are drawn with regard to AKIS appraisal in general and the usefulness of the AKIS concept, particularly for the understanding and evaluation of policy-induced innovation in agriculture.
Influence of Chinese economic fluctuations on tourism efficiency in national scenic areas
Authors: Cao Fangdong , Huang Zhenfang , Jin Cheng , Xu Min
Published: March 2015

This article measures and calculates tourism efficiency in Chinese national scenic areas. In order to analyse the characteristics of multi-scale fluctuations, the empirical mode decomposition (EMD) and wavelet decomposition methods are adopted. Specific Chinese national scenic areas are divided into several zones, with conclusions provided about the impact of economic fluctuations on their tourism efficiency. The results are as follows. The tourism efficiency of Chinese national scenic areas overall is not high; most have not yet reached data envelopment analysis (DEA) optimization; and the quasiperiodicity of scenic areas’ tourism efficiency mainly fluctuates between 2.42 and 9.67 years. Owing to the effects of extraneous factors, the significance of pure technical efficiency declined, which illustrates that economic development could promote technological progress, but technological progress is not a sufficient and necessary condition of economic development; studies of different periods show that a downward economic fluctuation will also facilitate technological improvement and promotion, which is the embodiment of the inverse periodicity of technological progress.
Children and Technology: Taking Time for Tech: Offering Support for Students through Technology
Authors: Smith Tara
Published: March 2015

While libraries have long been known as destinations for learning, research, and study, the methods we use to provide homework support must be continually updated, not only to demonstrate our relevance in a technological era, but also to ensure that the students we serve have access to the most up-to-date information and devices.
Spatial Variability of Urban Heat Island of Sargodha City in Pakistan
Authors: Sajjad Hussain Sajjad  , Sadaf Hussain  , Safdar Ali Shirazi  , Khadija Shakrullah  , Khuram Shahzad  , Rabia Batool  , S.M. Talha Qadri
Published: March 2015

Sargodha is one of the most important cities of Pakistan. Located in the center of Pakistan, it is the hub of the Pakistan Air Force. Rapid urbanization in the city has caused it to expand it farther from its center. Sargodha is 11th most populated metropolitan city in Pakistan. Currently, it has 0.7 million population and covers an area of 52 km2. The objective of this study was to measure the spatial variability of urban heat island (UHI) in different areas of the city in comparison with the temperature of the urban center. The meteorological data was measured by installing digital weather stations at four sites, 3 within the city by considering the areas as urban highly dense, urban less dense and urban periphery and one at rural site almost 10 km away from the city center. The result highlighted that difference in temperature between urban densely built area and rural site was highest. The difference in temperature increased as one moved away from the city center where urban areas were found warmer than the sites comparatively away from the city center. It was observed that the UHI intensity is not same in different areas of the city. The highest intensity of UHI is observed on Sunday where it was measured 5.7 °C.
Instructional Methods that Foster the Reading Development of Students with Significant Intellectual Disabilities
Authors: Wood-Fields Colleen , Judge Sharon , Watson Silvana M.R.
Published: March 2015

Educational legislation has made reading a priority for students with significant intellectual disabilities (ID) and associated speech, language, sensory, or physical impairments. Historically, reading instruction for students with significant ID has focused on sight word instruction, with limited exposure to other essential reading skills. This article focuses on the evidence-based instructional methods that effectively and efficiently foster the reading development of students with significant ID. The authors reviewed the literature from the past 20 years on reading interventions for students with significant ID. In spite of access and opportunity barriers that have inhibited the reading development of students with significant ID, a synthesis of the empirical research on reading instruction suggests that students with significant ID and associated disabilities can learn phonemic awareness, phonics, vocabulary, fluency, and comprehension skills with direct instruction. Implications for providing reading instruction that effectively promotes reading development are discussed and areas for future research are identified.
Migración residencial y urbanismo expansivo en el Mediterráneo español
Authors: Membrado Tena Joan Carles
Published: March 2015

Este artículo investiga la migración internacional de jubilados noreuropeos hacia España y su influencia en el desarrollo del urbanismo expansivo en nuestro país. Los temas clave que en este artículo se analizan son la expansión del urbanismo expansivo durante la burbuja inmobiliaria española, la cantidad y distribución de los jubilados noreuropeos residentes en España, y la relación entre la llegada de dichos migrantes residenciales y la difusión del urbanismo expansivo. Este artículo explica los motivos de esta migración residencial, que están principalmente relacionados con el clima y el estilo de vida mediterráneos. También describe los beneficios y los inconvenientes de dicha migración residencial y el impacto medioambiental y paisajístico sobre la España Mediterránea.
L’État libéral peut-il intervenir pour protéger les animaux? Défis et limites du libéralisme politique
Authors: Cormier Andrée-Anne
Published: March 2015

Cet article explore la question des implications de l’exclusion des animaux de la catégorie des sujets de justice dans le cadre du libéralisme politique de John Rawls. Plus spécifiquement, j’examine et critique les lectures de Ruth Abbey et de Robert Garner. Abbey suggère que le libéralisme politique est incompatible avec la thèse selon laquelle nous avons des devoirs moraux universels envers les animaux. Garner, pour sa part, avance que la théorie de Rawls n’autorise pas l’État libéral à adopter des mesures de protection des animaux. Dans cet article, je démontre que ces lectures sont erronées, car elles sont fondées sur des interprétations du libéralisme politique qui ne sont pas plausibles. Je soutiens, d’une part, que le libéralisme politique est neutre eu égard à la question de la nature de nos devoirs moraux envers les animaux et, d’autre part, qu’il permet de justifier une gamme considérable d’interventions étatiques visant la protection des animaux. Je suggère donc que la tension entre le libéralisme politique et l’éthique animale est moins forte que ne l’affirment ces auteurs. Enfin, j’identifie des stratégies possibles, cohérentes avec le cadre théorique rawlsien, pour élargir la sphère des sujets de justice de manière à y intégrer les animaux.
São Paulo e Buenos Aires: a construção da imagem de origem no século XX
Authors: Scapol Monteiro Michelli Cristine
Published: March 2015

This article examines four historical paintings from Brazil and Argentina: the Fundação de São Paulo by Oscar Pereira da Silva; the Fundação de São Paulo by Antônio Parreiras; the Primera Misa en Buenos Aires by José Bouchet; and the Fundación de Buenos Aires by José Moreno Carbonero. The objective is to understand the idea of nation that the political elites of these two countries constructed at the beginning of the 20th century. For this purpose, some of the connections among these works were studied in order to establish similarities and the social tensions caused by European immigration and by contact with indigenous groups.
C. elegans outside the Petri dish
Authors: Frézal Lise , Félix Marie-Anne
Published: March 2015

The roundworm Caenorhabditis elegans has risen to the status of a top model organism for biological research in the last fifty years. Among laboratory animals, this tiny nematode is one of the simplest and easiest organisms to handle. And its life outside the laboratory is beginning to be unveiled. Like other model organisms, C. elegans has a boom-and-bust lifestyle. It feasts on ephemeral bacterial blooms in decomposing fruits and stems. After resource depletion, its young larvae enter a migratory diapause stage, called the dauer. Organisms known to be associated with C. elegans include migration vectors (such as snails, slugs and isopods) and pathogens (such as microsporidia, fungi, bacteria and viruses). By deepening our understanding of the natural history of C. elegans, we establish a broader context and improved tools for studying its biology.
The effects of secular calcium and magnesium concentration changes on the thermodynamics of seawater acid/base chemistry: Implications for Eocene and Cretaceous ocean carbon chemistry and buffering
Authors: Hain Mathis P. , Sigman Daniel M. , Higgins John A. , Haug Gerald H.
Published: March 2015

Reconstructed changes in seawater calcium and magnesium concentration ([Ca2+], [Mg2+]) predictably affect the ocean's acid/base and carbon chemistry. Yet inaccurate formulations of chemical equilibrium “constants” are currently in use to account for these changes. Here we develop an efficient implementation of the MIAMI Ionic Interaction Model to predict all chemical equilibrium constants required for carbon chemistry calculations under variable [Ca2+] and [Mg2+]. We investigate the impact of [Ca2+] and [Mg2+] on the relationships among the ocean's pH, CO2, dissolved inorganic carbon (DIC), saturation state of CaCO3 (Ω), and buffer capacity. Increasing [Ca2+] and/or [Mg2+] enhances “ion pairing,” which increases seawater buffering by increasing the concentration ratio of total to “free” (uncomplexed) carbonate ion. An increase in [Ca2+], however, also causes a decline in carbonate ion to maintain a given Ω, thereby overwhelming the ion pairing effect and decreasing seawater buffering. Given the reconstructions of Eocene [Ca2+] and [Mg2+] ([Ca2+]~20 mM; [Mg2+]~30 mM), Eocene seawater would have required essentially the same DIC as today to simultaneously explain a similar‐to‐modern Ω and the estimated Eocene atmospheric CO2 of ~1000 ppm. During the Cretaceous, at ~4 times modern [Ca2+], ocean buffering would have been at a minimum. Overall, during times of high seawater [Ca2+], CaCO3 saturation, pH, and atmospheric CO2 were more susceptible to perturbations of the global carbon cycle. For example, given both Eocene and Cretaceous seawater [Ca2+] and [Mg2+], a doubling of atmospheric CO2 would require less carbon addition to the ocean/atmosphere system than under modern seawater composition. Moreover, increasing seawater buffering since the Cretaceous may have been a driver of evolution by raising energetic demands of biologically controlled calcification and CO2 concentration mechanisms that aid photosynthesis.
Isotopic evidence for nitrification in the Antarctic winter mixed layer
Authors: Smart Sandi M. , Fawcett Sarah E. , Thomalla Sandy J. , Weigand Mira A. , Reason Chris J. C. , Sigman Daniel M.
Published: March 2015

We report wintertime nitrogen and oxygen isotope ratios (δ15N and δ18O) of seawater nitrate in the Southern Ocean south of Africa. Depth profile and underway surface samples collected in July 2012 extend from the subtropics to just beyond the Antarctic winter sea ice edge. We focus here on the Antarctic region (south of 50.3°S), where application of the Rayleigh model to depth profile δ15N data yields estimates for the isotope effect (the degree of isotope discrimination) of nitrate assimilation (1.6–3.3‰) that are significantly lower than commonly observed in the summertime Antarctic (5–8‰). The δ18O data from the same depth profiles and lateral δ15N variations within the mixed layer, however, imply O and N isotope effects that are more similar to those suggested by summertime data. These findings point to active nitrification (i.e., regeneration of organic matter to nitrate) within the Antarctic winter mixed layer. Nitrite removal from samples reveals a low δ15N for nitrite in the winter mixed layer (−40‰ to −20‰), consistent with nitrification, but does not remove the observation of an anomalously low δ15N for nitrate. The winter data, and the nitrification they reveal, explain the previous observation of an anomalously low δ15N for nitrate in the temperature minimum layer (remnant winter mixed layer) of summertime depth profiles. At the same time, the wintertime data require a low δ15N for the combined organic N and ammonium in the autumn mixed layer that is available for wintertime nitrification, pointing to intense N recycling as a pervasive condition of the Antarctic in late summer.
Helium isotope, C/3He, and Ba‐Nb‐Ti signatures in the northern Lau Basin: Distinguishing arc, back‐arc, and hotspot affinities
Authors: Lupton John , Rubin Ken H. , Arculus Richard , Lilley Marvin , Butterfield David , Resing Joseph , Baker Edward , Embley Robert
Published: March 2015

The northern Lau Basin hosts a complicated pattern of volcanism, including Tofua Arc volcanoes, several back‐arc spreading centers, and individual “rear‐arc” volcanoes not associated with these structures. Elevated 3He/4He ratios in lavas of the NW Lau Spreading Center suggest the influence of a mantle plume, possibly from Samoa. We show that lavas from mid‐ocean ridges, volcanic arcs, and hotspots occupy distinct, nonoverlapping fields in a 3He/4He versus C/3He plot. Applied to the northern Lau Basin, this approach shows that most of Lau back‐arc spreading systems have mid‐ocean ridge 3He/4He‐C/3He characteristics, except the NW Lau spreading center, which has 3He/4He‐C/3He similar to “high 3He” hotspots such as Loihi, Kilauea, and Yellowstone, but with slightly lower C/3He. Niua seamount, on the northern extension of the Tofua Arc, falls squarely in the arc field. All the NE Lau rear‐arc volcanoes, including the recently erupting West Mata, also have arc‐like 3He/4He‐C/3He characteristics. Ba‐Nb‐Ti contents of the lavas, which are more traditional trace element indicators of mantle source enrichment, depletion, and subduction input, likewise indicate arc and hot spot influences in the lavas of the northern Lau Basin, but in a more ambiguous fashion because of a complex prior history. This verifies that 3He/4He‐C/3He systematics are useful for differentiating between mid‐ocean ridge, arc, and hotspot affinities in submarine volcanic systems, that all three of these affinities are expressed in the northern Lau Basin, and provides additional support for the Samoan plume influence in the region.
How weak is the subduction zone interface?
Authors: Duarte João C. , Schellart Wouter P. , Cruden Alexander R.
Published: March 2015

Several lines of evidence suggest that subduction zones are weak and that the unique availability of water on Earth is a critical factor in the weakening process. We have evaluated the strength of subduction zone interfaces using two approaches: (i) from empirical relationships between shear stress at the interface and subduction velocity, deduced from laboratory experiments; and (ii) from a parametric study of natural subduction zones that provides new insights on subduction zone interface strength. Our results suggest that subduction is only mechanically feasible when shear stresses along the plate interface are relatively low (less than ~35 MPa). To account for this requirement, we propose that there is a feedback mechanism between subduction velocity, water released from the subducting plate, and weakening of the fore‐arc mantle that may explain how relatively low shear stresses are maintained at subduction interfaces globally.
Nonlinear effects associated with kinetic Alfvén wave
Authors: Gaur Nidhi , Sharma R. P.
Published: March 2015

The nonlinear phenomena are of striking importance in understanding the particle acceleration, heating, and turbulence in the interplanetary space. Kinetic Alfvén wave (KAW) is one of the strong candidates responsible for accelerating the solar wind and powering the solar wind turbulence. Therefore, the nonlinear properties of KAW are attracting a good attention. In the present work, we have investigated the nonlinear effects associated with KAW in the solar wind plasma at around 1 A.U. The ponderomotive force of (relatively high frequency, high power) pump KAW may be used to excite the low‐frequency KAW (LKAW). For this purpose, we have derived the dynamical equations to analyze the nonlinear dynamics of relatively high frequency pump KAW in the presence of LKAW perturbation. The numerical solution has been carried out for the coupled system of equations by using the pseudospectral method for space integration and finite difference method along with the predictor corrector scheme for the evolution in time. The coupled system of nonlinear dynamical equations has been analyzed to study the nonlinear effects associated with pump KAW and the resulting turbulent spectra at 1 A.U.
Flow bursts, breakup arc, and substorm current wedge
Authors: Haerendel Gerhard
Published: March 2015

Energy liberated by the reconnection process in the near‐Earth tail is transported via flow bursts toward the dipolar magnetosphere during substorms. The breakup arc is a manifestation of the arrival of the bursts under flow braking and energy deposition. Its structure and behavior is analyzed on the basis of five striking spatial, temporal, and energetic properties, qualitatively and in part also quantitatively. A key element is the formation of stop layers. They are thin layers, of the width of an ion gyro radius, in which the magnetic field makes a transition from tail to near‐dipolar magnetosphere configurations and in which the kinetic energy of fast flows is converted into electromagnetic energy of kinetic Alfvén waves. The flows arise from the relaxation of the strong magnetic shear stresses in the leading part of the flow bursts. The bright narrow arcs of less than 10 km width inside the broad poleward expanding breakup arc, Alfvénic in nature and visually characterized by erratic short‐lived rays, are seen as traces of the stop layers. The gaps between two narrow and highly structured arcs are filled with more diffuse emissions. They are attributed to the relaxation of the less strained magnetic field of the flow bursts. Eastward flows along the arcs are linked to the shrinking gaps between two successive arcs and the entry of auroral streamers into the dipolar magnetosphere in the midnight sector. Flow braking in the stop layers forms multiple pairs of narrow balanced currents and cannot be behind the formation of the substorm current wedge. Instead, its origin is attributed to the force exerted by the dipolarized magnetic field of the flow bursts on the high‐beta plasma, after the high magnetic shears have relaxed and the fast flows and stop layer process have subsided, in other words, to the “dying flow bursts.”
Baroclinic instability and the mesoscale eddy field around the Lofoten Basin
Authors: Isachsen Pål Erik
Published: March 2015

The vigorous mesoscale eddy field around the Lofoten Basin west of northern Norway is thought to be related to eddy shedding from the Norwegian Atlantic Current flowing along the Norwegian coast. Here we study baroclinic instability in the current with a particular focus on the influence of topography. The flow over the steepest part of the continental slope is found to be the most unstable. The growth characteristics cannot be understood from Eady theory alone but require the consideration of interior potential vorticity gradients. A study of the fully developed macroturbulent field shows that eddy kinetic energy is advected away from the generation regions and that nonlinear effects likely draw the eddy statistics away from the linear growth regime.
An observational study of salt fluxes in Delaware Bay
Authors: Aristizábal María F. , Chant Robert J.
Published: March 2015

An observational study was conducted in Delaware Bay during the summer of 2011 aiming to quantify the different mechanisms driving the salt flux in this system. Seven moorings, equipped with bottom‐mounted ADCPs and CT sensors at difference depths, were deployed across a section of the estuary. The total area‐averaged and tidal‐averaged salt flux was decomposed in three different contributions: the advective salt flux that represents the flux caused by river input and meteorological‐induced flows, the steady shear dispersion that is the salt flux driven by the estuarine exchange flow, and the tidal oscillatory salt flux that is induced by the tidal currents. The advective salt flux dominated over the steady shear dispersion and tidal oscillatory salt flux, because it was driven mainly by changes in sea surface height associated with wind‐driven setup and setdown. The steady shear dispersion was always positive and presented a spring/neap variability that was consistent with a two‐layer exchange flow. On the other hand, the tidal oscillatory salt flux fluctuated between positive and negative values, but increased around a strong neap tide and decreased on the following spring tide. This variability is contrary to previous parameterizations, whereby the tidal salt flux is proportional to the amplitude of the tidal currents. The observational estimate was compared to a parameterization that relates tidal salt flux as proportional to tidal current amplitude and stratification. The observational estimate agreed with this new parameterization when the river discharge was relatively constant.
Thirteen thousand years of southeastern Mediterranean climate variability inferred from an integrative planktic foraminiferal‐based approach
Authors: Mojtahid Meryem , Manceau Rose , Schiebel Ralf , Hennekam Rick , de Lange Gert J.
Published: March 2015

Over the past 13 ka, the hydrology for the southeastern Mediterranean was mainly regulated by Nile River runoff, which in turn was controlled by climate forcing. Being affected by orbital forcing, and the position of the Intertropical Convergence Zone (ITCZ), planktic foraminiferal data (assemblages, stable isotopes, and size properties) indicate three major periods. (1) From 13.0 to 11.5 ka, the upper water column was well‐mixed, cold, and productive. (2) From 11.5 to 6.4 ka, hydrology and foraminifers were affected by intensified monsoonal circulation. The enhanced size of Globigerinoides ruber is interpreted as a response to environmental stress caused by low‐saline waters. (3) After 6.4 ka, the southward retreat of the ITCZ caused a decrease in freshwater discharge and hence a return to ecological equilibrium. A drop in foraminifer diversity from 2.9 to 1.1 ka was related to more arid conditions, and limited supply of nutrients from the Nile River. We suggest a link to a negative North Atlantic Oscillation (NAO) marking the Roman Humid Period in the western Mediterranean, and in anti‐phase with the southeastern Mediterranean aridity. Because Nile River runoff exerted major control on surface hydrology, a connection to Indian and Pacific climate systems partially controlling precipitation over the Nile catchment area is hypothesized. From 1.1 to 0.54 ka, high foraminifer diversity indicates humid conditions synchronous to the Medieval Climate Anomaly under a positive NAO state. Over the past 0.54 ka encompassing the Little Ice Age, another arid period is indicated by a drop in foraminifer diversity.
Glacial‐interglacial changes in central tropical Pacific surface seawater property gradients
Authors: Lynch‐Stieglitz Jean , Polissar Pratigya J. , Jacobel Allison W. , Hovan Steven A. , Pockalny Robert A. , Lyle Mitchell , Murray Richard W. , Ravelo A. Christina , Bova Samantha C. , Dunlea Ann G. , Ford Heather L. , Hertzberg Jennifer E. , Wertman Christina A. , Maloney Ashley E. , Shackford Julia K. , Wejnert Katherine , Xie Ruifang C.
Published: March 2015

Much uncertainty exists about the state of the oceanic and atmospheric circulation in the tropical Pacific over the last glacial cycle. Studies have been hampered by the fact that sediment cores suitable for study were concentrated in the western and eastern parts of the tropical Pacific, with little information from the central tropical Pacific. Here we present information from a suite of sediment cores collected from the Line Islands Ridge in the central tropical Pacific, which show sedimentation rates and stratigraphies suitable for paleoceanographic investigations. Based on the radiocarbon and oxygen isotope measurements on the planktonic foraminifera Globigerinoides ruber, we construct preliminary age models for selected cores and show that the gradient in the oxygen isotope ratio of G. ruber between the equator and 8°N is enhanced during glacial stages relative to interglacial stages. This stronger gradient could reflect enhanced equatorial cooling (perhaps reflecting a stronger Walker circulation) or an enhanced salinity gradient (perhaps reflecting increased rainfall in the central tropical Pacific).
Front spreading with nonlinear sorption for oscillating flow
Authors: Cirkel D. G. , van der Zee S. E. A. T. M. , Meeussen J. C. L.
Published: March 2015

In this paper, we consider dispersive and chromatographic mixing at an interface, under alternating flow conditions. In case of a nonreactive or linearly sorbing solute, mixing is in complete analogy with classical dispersion theory. For nonlinear exchange, however, oscillating convective flow leads to an alternation of sharpening (Traveling Wave TW) and spreading (Rarefaction Wave RW). As the limiting TW form is not necessarily accomplished at the end of the TW half cycle, the oscillating fronts show gradual continuous spreading that converges to a zero‐convection nonlinear pure diffusion spreading, which is mathematically of quite different nature. This behavior is maintained in case the total (background) concentration differs at both sides of the initial exchange front.
Transport of fluorobenzoate tracers in a vegetated hydrologic control volume: 1. Experimental results
Authors: Queloz Pierre , Bertuzzo Enrico , Carraro Luca , Botter Gianluca , Miglietta Franco , Rao P. S. C. , Rinaldo Andrea
Published: March 2015

This paper reports about the experimental evidence collected on the transport of five fluorobenzoate tracers injected under controlled conditions in a vegetated hydrologic volume, a large lysimeter (fitted with load cells, sampling ports, and an underground chamber) where two willows prompting large evapotranspiration fluxes had been grown. The relevance of the study lies in the direct and indirect measures of the ways in which hydrologic fluxes, in this case, evapotranspiration from the upper surface and discharge from the bottom drainage, sample water and solutes in storage at different times under variable hydrologic forcings. Methods involve the accurate control of hydrologic inputs and outputs and a large number of suitable chemical analyses of water samples in discharge waters. Mass extraction from biomass has also been performed ex post. The results of the 2 year long experiment established that our initial premises on the tracers’ behavior, known to be sorption‐free under saturated conditions which we verified in column leaching tests, were unsuitable as large differences in mass recovery appeared. Issues on reactivity thus arose and were addressed in the paper, in this case attributed to microbial degradation and solute plant uptake. Our results suggest previously unknown features of fluorobenzoate compounds as hydrologic tracers, potentially interesting for catchment studies owing to their suitability for distinguishable multiple injections, and an outlook on direct experimental closures of mass balance in hydrologic transport volumes involving fluxes that are likely to sample differently stored water and solutes.
Transport of fluorobenzoate tracers in a vegetated hydrologic control volume: 2. Theoretical inferences and modeling
Authors: Queloz Pierre , Carraro Luca , Benettin Paolo , Botter Gianluca , Rinaldo Andrea , Bertuzzo Enrico
Published: March 2015

A theoretical analysis of transport in a controlled hydrologic volume, inclusive of two willow trees and forced by erratic water inputs, is carried out contrasting the experimental data described in a companion paper. The data refer to the hydrologic transport in a large lysimeter of different fluorobenzoic acids seen as tracers. Export of solute is modeled through a recently developed framework which accounts for nonstationary travel time distributions where we parameterize how output fluxes (namely, discharge and evapotranspiration) sample the available water ages in storage. The relevance of this work lies in the study of hydrologic drivers of the nonstationary character of residence and travel time distributions, whose definition and computation shape this theoretical transport study. Our results show that a large fraction of the different behaviors exhibited by the tracers may be charged to the variability of the hydrologic forcings experienced after the injection. Moreover, the results highlight the crucial, and often overlooked, role of evapotranspiration and plant uptake in determining the transport of water and solutes. This application also suggests that the ways evapotranspiration selects water with different ages in storage can be inferred through model calibration contrasting only tracer concentrations in the discharge. A view on upscaled transport volumes like hillslopes or catchments is maintained throughout the paper.
What do we mean by sensitivity analysis? The need for comprehensive characterization of “global” sensitivity in Earth and Environmental systems models
Authors: Razavi Saman , Gupta Hoshin V.
Published: March 2015

Sensitivity analysis is an essential paradigm in Earth and Environmental Systems modeling. However, the term “sensitivity” has a clear definition, based in partial derivatives, only when specified locally around a particular point (e.g., optimal solution) in the problem space. Accordingly, no unique definition exists for “global sensitivity” across the problem space, when considering one or more model responses to different factors such as model parameters or forcings. A variety of approaches have been proposed for global sensitivity analysis, based on different philosophies and theories, and each of these formally characterizes a different “intuitive” understanding of sensitivity. These approaches focus on different properties of the model response at a fundamental level and may therefore lead to different (even conflicting) conclusions about the underlying sensitivities. Here we revisit the theoretical basis for sensitivity analysis, summarize and critically evaluate existing approaches in the literature, and demonstrate their flaws and shortcomings through conceptual examples. We also demonstrate the difficulty involved in interpreting “global” interaction effects, which may undermine the value of existing interpretive approaches. With this background, we identify several important properties of response surfaces that are associated with the understanding and interpretation of sensitivities in the context of Earth and Environmental System models. Finally, we highlight the need for a new, comprehensive framework for sensitivity analysis that effectively characterizes all of the important sensitivity‐related properties of model response surfaces.
A new method for global retrievals of HCHO total columns from the Suomi National Polar‐orbiting Partnership Ozone Mapping and Profiler Suite
Authors: Li Can , Joiner Joanna , Krotkov Nickolay A. , Dunlap Laura
Published: March 2015

We introduce a new method for retrieving formaldehyde (HCHO) based on principal component analysis (PCA) of satellite‐measured radiances. Applying the technique to the Suomi National Polar‐orbiting Partnership/Ozone Mapping and Profiler Suite (S‐NPP/OMPS) radiances between 328.5 and 356.5 nm, we extract principal components (PCs) associated with various physical processes (e.g., ozone absorption and rotational Raman scattering) and measurement details (e.g., wavelength shift). These PCs, along with precomputed HCHO Jacobians, are utilized in spectral fitting to estimate HCHO loading and reduce interferences. Comparisons with model simulations and independent Ozone Monitoring Instrument (OMI) retrievals indicate that our algorithm can detect enhanced HCHO signals over source regions such as the southeast U.S., producing HCHO total columns with similar spatial distributions and seasonal patterns. While our OMPS retrievals are ~15–20% lower than OMI retrievals from a different algorithm, the differences may be attributed to several instrumental and algorithmic factors. This study demonstrates the potential of PCA algorithms and of OMPS for continuing the long‐term satellite HCHO data record.
Twentieth century dust lows and the weakening of the westerly winds over the Tibetan Plateau
Authors: Grigholm B. , Mayewski P. A. , Kang S. , Zhang Y. , Morgenstern U. , Schwikowski M. , Kaspari S. , Aizen V. , Aizen E. , Takeuchi N. , Maasch K. A. , Birkel S. , Handley M. , Sneed S.
Published: March 2015

Understanding past atmospheric dust variability is necessary to put modern atmospheric dust into historical context and assess the impacts of dust on the climate. In Asia, meteorological data of atmospheric dust is temporally limited, beginning only in the 1950s. High‐resolution ice cores provide the ideal archive for reconstructing preinstrumental atmospheric dust concentrations. Using a ~500 year (1477–1982 A.D.) annually resolved calcium (Ca) dust proxy from a Tibetan Plateau (TP) ice core, we demonstrate the lowest atmospheric dust concentrations in the past ~500 years during the latter twentieth century. Declines in late nineteenth to twentieth century Ca concentrations significantly correspond with regional zonal wind trends from two reanalysis models, suggesting that the Ca record provides a proxy for the westerlies. Twentieth century warming and attendant atmospheric pressure reductions over northern Asia have potentially reduced temperature/pressure gradients resulting in lower zonal wind velocities and associated dust entrainment/transport in the past ~500 years over the TP.
Monsoonal hillslope processes determine grain size‐specific suspended sediment fluxes in a trans‐Himalayan river
Authors: Struck Martin , Andermann Christoff , Hovius Niels , Korup Oliver , Turowski Jens M. , Bista Raj , Pandit Hari P. , Dahal Ranjan K.
Published: March 2015

Sediments in rivers record the dynamics of erosion processes. While bulk sediment fluxes are easily and routinely obtained, sediment caliber remains underexplored when inferring erosion mechanisms. Yet sediment grain size distributions may be the key to discriminating their origin. We have studied grain size‐specific suspended sediment fluxes in the Kali Gandaki, a major trans‐Himalayan river. Two strategically located gauging stations enable tracing of sediment caliber on either side of the Himalayan orographic barrier. The data show that fine sediment input into the northern headwaters is persistent, while coarse sediment comes from the High Himalayas during the summer monsoon. A temporally matching landslide inventory similarly indicates the prominence of monsoon‐driven hillslope mass wasting. Thus, mechanisms of sediment supply can leave strong traces in the fluvial caliber, which could project well beyond the mountain front and add to the variability of the sedimentary record of orogen erosion.
A detailed analysis of wastewater‐induced seismicity in the Val d'Agri oil field (Italy)
Authors: Improta Luigi , Valoroso Luisa , Piccinini Davide , Chiarabba Claudio
Published: March 2015

The Val d'Agri basin in the Apennines seismic belt hosts the largest oil field in onshore Europe. High‐quality recordings from a temporary dense network unravel a swarm of 111 small‐magnitude events (ML ≤ 1.8) occurred in June 2006 during the first stage of wastewater injection into a high‐rate well. High‐precision relative locations define a preexisting blind fault located 1 km below the well inside fractured and saturated carbonates where wastewater is reinjected. Seismicity begins 3 h after the initiation of injection. The seismicity rate strictly correlates with injection curves and temporal variations of elastic and anisotropic parameters. Seismicity is induced by rapid communication of pore pressure perturbations along a high‐permeability fault zone favorably oriented with respect to the local extensional stress field. Our accurate 3‐D locations of 219 events (ML ≤ 2.2) detected by the local operator network after June 2006 concentrate on the preexisting fault measuring 5 km along dip. Over the following 7.5 years, the seismicity rate correlates with short‐term increases in injection pressure.
Effect of Enceladus's rapid synchronous spin on interpretation of Cassini gravity
Authors: McKinnon William B.
Published: March 2015

Enceladus's degree 2 gravity, determined by Cassini, is nominally nonhydrostatic to 3σ (J2/C22 = 3.38–3.63, as opposed to 10/3). Iess et al. (2014) interpret this in terms of a hydrostatic interior (core) and isostatic (not hydrostatic) floating ice shell. Enceladus's rapid (1.37 d) synchronous spin and tide distorts its shape substantially, though, enough that the predicted hydrostatic J2/C22 is not 10/3 but closer to 3.25. This leads to the following revision to the internal picture of Enceladus, compared with Iess et al.: (1) the satellite's core is somewhat smaller and slightly denser (190 km radius and 2450 kg/m3); (2) the compensation depth (shell thickness) of the global (degree 2) ice shell is ≈ 50 km, rather close to the base of the modeled ice + water layer; and (3) the compensation depth (shell thickness) beneath the South Polar Terrain (from J3) remains shallower (thinner) at ≈ 30 km, independent of but influenced by the degree 2 solution.