bluuebunny/crossref_metadata_2025 huggingface dataset:
Approches socio-historiques des «trois cultures ibériques» par le prisme de la mosaïque socioculturelle de Melila
Authors: Fernández García Alicia
Published: October 2018

Pendant près de trois siècles la péninsule connaîtra une importante cohabitation entre Chrétiens Musulmans et Juifs, ce qu'il convient de nommer l'Espagne des «trois cultures ibériques». À la fin du XIe siècle, les relations entre les distinctes cultures ibériques vont se détériorer durablement en raison de la Reconquête menée par Alphonse VI. Il semble dune indispensable de s'intéresser aux contributions arabe et juive dans la formation de cette « Espagne des trois cultures». Néanmoins, l'historiographie existante relative à cette Espagne plurielle se focalise principalement sur le territoire de la péninsule ibérique, bien qu'il existe au sein même du territoire espagnol des zones de marges, de & entières où les interactions entre les «trois cultures ibériques» s'exprimèrent au passé tout autant qu'elles continuent à se perpétuer au présent. Sur ce plan notre contribution tentera d'étudier les dynamiques des relations interculturelles d'une ville héritière et contemporaine à la fois de l'Espagne de "trois culture", afin de repenser, à partir de ses propres marges, cette Espagne se conjuguant au pluriel. Ville espagnole méditerranéenne appartenant pourtant au continent africain et se situant sur la côte nord-est du Rif oriental du Maroc, Melilla, est un laboratoire des «trois cultures ibériques» qui cultive les paradoxes culturels et sociaux. La ville, fut tant un lieu d'immigration privilégié des juifs, des maures et des mudéjares expulsés de la péninsule ibérique suite à la reconquête, puis un refuge pour les sépharades persécutés du Maroc, de même qu'un nouvel eldorado pour les colons espagnols péninsulaires.
La régulation de l'audiovisuel au Maroc: un choix irréversible ou un alibi?
Authors: Varol Marie-Christine
Published: October 2018

La libéralisation du paysage audiovisuel marocain a commencé de manière quasi-informelle dans les années 80, avec notamment la création de la radio franco-marocaine, Medil et de la chaine de télévision hertzienne 2M, avant que cette dernière, confrontée à des difficultés financières, ne rejoigne le giron du service public. Mais ce n'est qu'en 2002 que la libéralisation du PAM a été formellement inscrite dans la loi, avec notamment la création de l'instant de régulation du paysage audiovisuel marocain, la Haute Autorité de la Communication Audiovisuelle (HACA). En 2006 et 2009, en deux vagues, la HACA a accordé des licences à une quinzaine de radios privées qui sont venues enri chir le paysage radiophonique marocain et susciter un véritable engouement pour ce média dans le public. Mais en matière de télévision, seule MedilSat, une té1évision satellitaire a été autorisée en 2006. Actuellement le processus de libéralisation marque le pas et la HACA semble essoufflée. Y aura-t-il un second souffle salutaire ou bien le processus a-t-il épuisé les objectifs qui lui étaient assignés ?
Internet en Tunisie : régulation, usages et confits émergents
Authors: Mihoub Sarnia
Published: October 2018

En Tunisie, Internet est placé sous l'emprise de l'État. Cependant, on observe un engouement toujours plus grand des citoyens pour la navigation sur le réseau. D'une part, on observe des habitudes de navigation marquées par l'autocensure et la stratégie de l'évitement des sites «à risque». De plus, l'utilisation des applications sociales du Web 2.0 sont devenues une activité de prédilection des jeunes tunisiens. D'autre parti certaines velléités d'opposition et de «désobéissance», tentent l non sans difficultés, d'émerger sur le réseau. Nous verrons dans cet article comment la régulation de l'accès et des usages d'Internet débouche sur une confiscation du réseau engendrant d'abord une uniformisation des usages, ensuite un conflit entre État

et société civile.
Carbonylonium ions: the onium ions of the carbonyl group
Authors: Blanco-Ania Daniel , Rutjes Floris P J T
Published: October 2018

The nomenclature of cations R1C(=O+R3)R2 (R1, R2, R3 = H or organyl) has been examined and shown to be in a state of immeasurable confusion: a pragmatic recommendation is made that the generic term “carbonylonium ions” should be adopted for these intermediates, which comprises the terms “aldehydium” (R1 = H, R2, R3 = H or organyl) and “ketonium ions” (R1, R2 = organyl, R3 = H or organyl) for the corresponding aldehyde- and ketone-based intermediates, respectively.
Alumina Polymorphism in the Circumstellar Dust Shells of Asymptotic Giant Branch Stars
Authors: Sargent Benjamin A.
Published: October 2018

Many emission features remain unidentified in the infrared spectra of asymptotic giant branch (AGB) stars. In particular, features at ∼11, 20, 28, and 32 μm have been noted in mid-infrared spectra of oxygen-rich AGB stars. Here, I present models of dust excess emission in 36 spectra of 24 AGB stars from the Short Wavelength Spectrometer on board the Infrared Space Observatory and the Infrared Spectrograph on the Spitzer Space Telescope. The models include opacities of grains composed of mixtures of various polymorphs of alumina obtained by preparing bayerite and boehmite at high temperatures, and these dust components provide satisfactory fits to the 11, 20, 28, and 32 μm features. Though not a direct conclusion from this study, the presence of grains of the various polymorphs of aluminas in circumstellar dust shells around AGB stars suggests that corundum may have a role in giving rise to the 13 μm feature.
The Close AGN Reference Survey (CARS): SOFIA Detects Spatially Resolved [C ii] Emission in the Luminous AGN HE 0433-1028∗
Authors: Busch G. , Husemann B. , Smirnova-Pinchukova I. , Eckart A. , Baum S. A. , Combes F. , Croom S. M. , Davis T. A. , Fazeli N. , Fischer C. , Gaspari M. , Klein R. , Krumpe M. , McElroy R. , O’Dea C. P. , Perez-Torres M. A. , Powell M. C. , Sánchez-Monge Á. , Scharwächter J. , Tremblay G. R. , Urrutia T.
Published: October 2018

We report spatially resolved [C ii] λ158 μm observations of HE 0433-1028, which is the first detection of a nearby luminous active galactic nucleus (AGN; redshift 0.0355) with the Field-Imaging Far-Infrared Line Spectrometer (FIFI-LS) on board the airborne Stratospheric Observatory For Infrared Astronomy (SOFIA). We compare the spatially resolved star formation tracers [C ii], as provided by our SOFIA observations, and Hα from the Multi Unit Spectroscopic Explorer (MUSE) optical integral-field spectroscopy. We find that the [C ii] emission is mainly matching the extended star formation as traced by the extinction-corrected Hα line emission but some additional flux is present. While a larger sample is needed to statistically confirm our findings and investigate possible dependencies on AGN luminosity and star formation rate, our study underlines the necessity of collecting a spatially resolved optical–far-infrared data set for nearby AGNs, and shows that it is technically feasible to collect such data sets with FIFI-LS on board SOFIA.
Histopathology of the skin in rheumatic diseases
Authors: Chimenti M.S. , Di Stefani A. , Conigliaro P. , Saggini A. , Urbani S. , Giunta A. , Esposito M. , Bianchi L. , Peris K. , Perricone R.
Published: October 2018

Rheumatological systemic autoimmune diseases, such as connective tissue diseases, rheumatoid arthritis or spondyloarthritis, are characterized by the presence of joint involvement associated with extra-articular manifestations. Among them, cutaneous diseases are often the most relevant and representative clinical manifestation, as in psoriatic arthritis, scleroderma or systemic lupus erythematosus. In this context, it is useful for rheumatologists to understand better skin diseases and their histopathological features. Evaluation of skin biopsy specimens can be helpful not only to confirm the diagnosis in both classic and clinically atypical variants, but also to improve further our knowledge of the pathogenetic mechanisms and the close link between skin and articular diseases. In this review, we discuss the clinical features, diagnostic evaluation and the histopathological features of skin manifestation of the most relevant rheumatological autoimmune diseases.
Histopathology of the synovial tissue: perspectives for biomarker development in chronic inflammatory arthritides
Authors: Manzo A. , Bugatti S. , Caporali R. , Montecucco C.
Published: October 2018

The histopathological and molecular analysis of the synovial tissue has contributed to fundamental advances in our comprehension of arthritis pathogenesis and of the mechanisms of action of currently available treatments. On the other hand, its exploitation in clinical practice for diagnostic or prognostic purposes as well as for the prediction of treatment response to specific disease-modifying anti-rheumatic drugs is still limited. In this review, we present an overview of recent advances in the field of synovial tissue research with specific reference to the methods for synovial tissue collection, approaches to synovial tissue analysis and current perspectives for the exploitation of synovial tissue-derived biomarkers in chronic inflammatory arthritides.
Histopathology of vasculitis
Authors: Bajocchi G. , Cavazza A.
Published: October 2018

The range of pathologies that are related to primitive vasculitis is broad, complex and not as typical as we would expect. Clinicians should be aware that several forms of primitive and systemic vasculitis, regardless of the size of the affected vessel, may exhibit identical histological alterations. This observation has important clinical implications as it means that cases of vasculitis do not correspond clinically and histologically. Thus, while histology remains the diagnostic gold standard, it can be used only as part of the most complete clinical assessment possible. Another point worth of the clinician’s attention is that vasculitis histology changes over time, as do disease evolution and activity, even without considering the masking effects of treatment and the possibility of sampling error due to the patchy occurrence of vasculitis. The purpose of this review is to identify the most common forms of vasculitis in clinical practice, and to provide guidance to the clinician on the pathology of the vessels.
Oscillatory thresholds and foveal and macular thickness using coherence tomography
Authors: Humphreys Amy , Rubin Alan
Published: October 2018

Background: Technology is evolving and advancing rapidly as is evident in the ophthalmic and optometric fields with the development of new equipment and software programs that assist in the examination of patients and diagnoses of ocular diseases. The new vision psychophysical software for measurements of oscillatory sensitivity (OS) is a recently developed program that can be used to assess visual ability at the fovea by establishing oscillatory thresholds (OT) and it is therefore necessary to assess the reliability and repeatability of this new software.Aim: The goal of this study was to assess the reliability and repeatability of the new vision psychophysical software for measuring OS with special focus on the macular and foveal area.Setting: This study took place at the Department of Optometry at the University of Johannesburg between 2016 and 2017.Methods: To measure OS, an ascending threshold method was used where a simple target was presented, with increasing oscillations until perception of movement occurred. Healthy participants (N = 37), with a mean age of 22.43 ± 2.57 years, were asked to indicate when the high contrast circular (2 mm) target began oscillating on a stationary black background. The target was used at nine points in the macular region to measure OT. Each macular map was measured twice per participant and only the right eyes were involved. Retinal thicknesses were also evaluated using the spectral-domain iVue 100 optical coherence tomography (OCT) from Optovue. Macular thickness and OS (along with OT) measurements were assessed using various graphical and statistical methods to establish test–retest reliability and repeatability.Results: The study focused on OS and retinal thickness measurements of the macular and foveal regions. For retinal thickness measurements, repeatability and reliability were good, data was normally distributed and agreement between test–retest measurements was high, while OS measurements had good repeatability and reliability, were not normally distributed but had good agreement between test–retest measurements. With healthy participants, no correlations between OCT and OS measurements were found (r = −0.14, p = 0.49 and r = 0.03, p = 0.89 for test and retest samples).Conclusion: The results for both procedures suggest that there is good reliability and repeatability within the macular region. Both methods can be used with confidence clinically and in future studies.
A qualitative approach to the entrepreneurial education and intentions nexus: A case of Zimbabwean polytechnic students
Authors: Ndofirepi Takawira M. , Rambe Patient
Published: October 2018

Background: Owing to the popularity of entrepreneurship as an alternative to formal employment, entrepreneurship education has become the main instrument for equipping graduates with survivalist and innovative skills for new venture creation in their post-college life. However, despite the growing body of literature on the entrepreneurship education–entrepreneurial intention nexus, there are limited studies based on qualitative methodologies covering this relationship.Aim: This article develops an in-depth understanding of the interface between exposure to entrepreneurship education and the entrepreneurial intention of students.Setting: The study draws on the perceptions of 27 purposively selected national certificate level students at a Zimbabwean polytechnic.Methods: The study used an interpretive qualitative research design, with data being collected through focus group discussions.Results: Findings suggest that while passive learning and teaching methods were critical to orienting students towards the entrepreneurship field, over-dependence on theoretical content, teacher-dominated delivery, the absence of deep practical orientation and engagement with industry undermined the significance of tertiary level entrepreneurship education.Conclusion: To enrich the development of potential entrepreneurs, the implication of these findings is that educators and policymakers should address various aspects of the entrepreneurship education value chain (from content creation, delivery strategy, enhancing practical orientation of the subject, and developing lasting relations with industry long before entrepreneurship starts) that potentially affect students’ willingness to engage in future entrepreneurship.
Topological characterization of Gelfand and zero dimensinal semirings
Authors: Vielma Jorge , Marchan Luz
Published: October 2018

Let R be a conmutative semiring with 0 and 1, and let Spec(R) be the set of all proper prime ideals of R. Spec(R) can be endowed with two topologies, the Zariski topology and the D-topology.  Let Max R denote the set of all maximals  prime ideals of R. We prove that the two topologies coincide on Spec(R) and on Max R if and only if R is zero dimensional and Gelfand semiring, respectively.
Completely simple endomorphism rings of modules
Authors: Bovdi Victor , Salim Mohamed , Ursul Mihail
Published: October 2018

It is proved that if Ap is a countable elementary abelian p-group, then: (i) The ring End (Ap) does not admit a nondiscrete locally compact ring topology. (ii) Under (CH) the simple ring End (Ap)/I, where I is the ideal of End (Ap) consisting of all endomorphisms with finite images, does not admit a nondiscrete locally compact ring topology. (iii) The finite topology on End (Ap) is the only second metrizable ring topology on it. Moreover, a characterization of completely simple endomorphism rings of modules over commutative rings is obtained.
τ-metrizable spaces
Authors: Megaritis A.C.
Published: October 2018

In [1], A. A. Borubaev introduced the concept of τ-metric space, where τ is an arbitrary cardinal number. The class of τ-metric spaces as τ runs through the cardinal numbers contains all ordinary metric spaces (for τ = 1) and thus these spaces are a generalization of metric spaces. In this paper the notion of τ-metrizable space is considered.
Mixing state and particle hygroscopicity of organic-dominated aerosols over the Pearl River Delta region in China
Authors: Hong Juan , Xu Hanbing , Tan Haobo , Yin Changqing , Hao Liqing , Li Fei , Cai Mingfu , Deng Xuejiao , Wang Nan , Su Hang , Cheng Yafang , Wang Lin , Petäjä Tuukka , Kerminen Veli-Matti
Published: October 2018

Abstract. Simultaneous measurements of aerosol hygroscopicity and particle-phase
chemical composition were performed at a suburban site over the Pearl River
Delta region in the late summer of 2016 using a self-assembled hygroscopic
tandem differential mobility analyzer (HTDMA) and an Aerodyne quadruple
aerosol chemical speciation monitor (ACSM), respectively. The
hygroscopic growth factor (HGF) of the Aitken mode (30 nm, 60 nm) and
accumulation mode (100 nm, 145 nm) particles were obtained under 90 %
relative humidity (RH). An external mixture was observed for particles of
every size during this study, with a dominant mode of more-hygroscopic (MH)
particles, as aged aerosols dominated due to the anthropogenic
influence. The HGF of less-hygroscopic (LH) mode particles increased, while
their number fractions decreased during the daytime due to a reduced degree
of external mixing that probably resulted from the condensation of gaseous
species. These LH mode particles in the early morning or late afternoon could
be possibly dominated by carbonaceous material emitted from local automobile
exhaust during rush hours. During polluted days with air masses flowing
mainly from the coastal areas, the chemical composition of aerosols had a
clear diurnal variation and a strong correlation with the mean HGF. Closure
analysis was carried out between the HTDMA-measured HGF and the ACSM-derived
hygroscopicity using various approximations for the hygroscopic growth factor
of organic compounds (HGForg). Considering the assumptions
regarding the differences in the mass fraction of each component between
PM1 and 145 nm particles, the hygroscopicity-composition closure was
achieved using an HGForg of 1.26 for the organic material in the
145 nm particles and a simple linear relationship between the
HGForg and the oxidation level inferred from the O:C ratio
of the organic material was suggested. Compared with the results from other
environments, HGForg obtained from our measurements appeared to
be less sensitive to the variation of its oxidation level, which is, however,
similar to the observations in the urban atmosphere of other megacities in
China. This finding suggests that the anthropogenic precursors or the
photooxidation mechanisms might differ significantly between the suburban and
urban atmosphere in China and those in other background environments. This
may lead to different characteristics of the oxidation products in secondary
organic aerosols (SOA) and therefore to a different relationship between the
HGForg and its O:C ratio.
Trends in China's anthropogenic emissions since 2010 as the consequence of clean air actions
Authors: Zheng Bo , Tong Dan , Li Meng , Liu Fei , Hong Chaopeng , Geng Guannan , Li Haiyan , Li Xin , Peng Liqun , Qi Ji , Yan Liu , Zhang Yuxuan , Zhao Hongyan , Zheng Yixuan , He Kebin , Zhang Qiang
Published: October 2018

Abstract. To tackle the problem of severe air pollution, China has implemented active
clean air policies in recent years. As a consequence, the emissions of major
air pollutants have decreased and the air quality has substantially improved.
Here, we quantified China's anthropogenic emission trends from 2010 to 2017
and identified the major driving forces of these trends by using a
combination of bottom-up emission inventory and index decomposition analysis
(IDA) approaches. The relative change rates of China's anthropogenic
emissions during 2010–2017 are estimated as follows: −62 % for
SO2, −17 % for NOx, +11 % for nonmethane
volatile organic compounds (NMVOCs), +1 % for NH3, −27 %
for CO, −38 % for PM10, −35 % for PM2.5, −27 %
for BC, −35 % for OC, and +16 % for CO2. The IDA results
suggest that emission control measures are the main drivers of this
reduction, in which the pollution controls on power plants and industries are
the most effective mitigation measures. The emission reduction rates markedly
accelerated after the year 2013, confirming the effectiveness of China's
Clean Air Action that was implemented since 2013. We estimated that during
2013–2017, China's anthropogenic emissions decreased by 59 % for
SO2, 21 % for NOx, 23 % for CO, 36 % for
PM10, 33 % for PM2.5, 28 % for BC, and 32 % for OC.
NMVOC emissions increased and NH3 emissions remained stable during
2010–2017, representing the absence of effective mitigation measures for
NMVOCs and NH3 in current policies. The relative contributions of
different sectors to emissions have significantly changed after several
years' implementation of clean air policies, indicating that it is paramount
to introduce new policies to enable further emission reductions in the
future.
Effects of Urbanization on Regional Meteorology and Air Quality in
Southern California
Authors: Li Yun , Zhang Jiachen , Sailor David J. , Ban-Weiss George A.
Published: October 2018

Abstract. Urbanization has a profound influence on regional meteorology and air quality in megapolitan Southern California. The influence of urbanization on meteorology is driven by changes in land surface physical properties and land surface processes. These changes in meteorology in turn influence air quality by changing temperature-dependent chemical reactions and emissions, gas-particle phase partitioning, and ventilation of pollutants. In this study we characterize the influence of historical urbanization from before human settlement to present-day on meteorology and air quality in Southern California using the Weather Research and Forecasting Model coupled to chemistry and the single-layer urban canopy model (WRF/Chem-UCM). We assume identical anthropogenic emissions for the simulations carried out, and thus focus on the effect of changes in land surface physical properties and land surface processes on air quality. Historical urbanization has led to daytime air temperature decreases of up to 1.4 K, and evening temperature increases of up to 1.7 K. Ventilation of air in the LA basin has decreased up to 36.6 % during daytime and increased up to 27.0 % during nighttime. These changes in meteorology are mainly attributable to higher evaporative fluxes from irrigation, higher thermal inertia from irrigation and building materials, and increased surface roughness from buildings. Changes in ventilation drive changes in hourly NOx concentrations with increases of up to 2.7 ppb during daytime and decreases of up to 4.7 ppb at night. Hourly O3 concentrations decrease by up to 0.94 ppb in the morning, and increase by up to 5.6 ppb at other times of day. Changes in O3 concentrations are driven by the competing effects of changes in ventilation and precursor NOx concentrations. PM2.5 concentrations show slight increases during the day, and decreases of up to 2.5 μg/m3 at night. Processes drivers for changes in PM2.5 include modifications to atmospheric ventilation, and temperature, which impacts gas-particle phase partitioning for semi-volatile compounds and chemical reactions. Understanding processes drivers for how land surface changes effect regional meteorology and air quality is crucial for decision making on urban planning in megapolitan Southern California to achieve regional climate adaptation and air quality improvements.
Assessing uncertainties of a geophysical approach to estimate surface fine particulate matter distributions from satellite observed aerosol optical depth
Authors: Jin Xiaomeng , Fiore Arlene M. , Curci Gabriele , Lyapustin Alexei , Civerolo Kevin , Ku Michael , van Donkelaar Aaron , Martin Randall V.
Published: October 2018

Abstract. Health impact analyses are increasingly tapping the broad spatial coverage of satellite aerosol optical depth (AOD) products to estimate human exposure to fine particulate matter (PM2.5). We use a forward geophysical approach to derive ground-level PM2.5 distributions from satellite AOD at 1 km2 resolution for 2011 over the Northeast USA by applying relationships between surface PM2.5 and column AOD (calculated offline from speciated mass distributions) from a regional air quality model (CMAQ; 12 × 12 km2 horizontal resolution). Seasonal average satellite-derived PM2.5 reveals more spatial detail and best captures observed surface PM2.5 levels during summer. At the daily scale, however, satellite-derived PM2.5 is not only subject to measurement uncertainties from satellite instruments, but more importantly, to uncertainties in the relationship between surface PM2.5 and column AOD. Using 11 ground-based AOD measurements within 10 km of surface PM2.5 monitors, we show that uncertainties in modeled PM2.5/AOD can explain more than 70 % of the spatial and temporal variance in the total uncertainty in daily satellite-derived PM2.5 evaluated at PM2.5 monitors. This finding implies that a successful geophysical approach to deriving daily PM2.5 from satellite AOD requires model skill at capturing day-to-day variations in PM2.5/AOD relationships. Overall, we estimate that uncertainties in the modeled PM2.5/AOD lead to an error of 11 μg/m3 in daily satellite-derived PM2.5, and uncertainties in satellite AOD lead to an error of 8 μg/m3. Using multi-platform ground, airborne and radiosonde measurements, we show that uncertainties of modeled PM2.5/AOD are mainly driven by model uncertainties in aerosol column mass and speciation, while model uncertainties of relative humidity and aerosol vertical profile shape contribute some systematic biases. The parameterization of aerosol optical properties, which determines the mass-extinction efficiency, also contributes to random uncertainty, with the size distribution the largest source of uncertainty, and hygroscopicity of inorganic salt the second. Future efforts to reduce uncertainty in geophysical approaches to derive surface PM2.5 from satellite AOD would thus benefit from improving model representation of aerosol vertical distribution and aerosol optical properties, to narrow uncertainty in satellite-derived PM2.5.
Characterization of lower-cost medium precision atmospheric CO2 monitoring systems for urban areas using commercial NDIR sensors
Authors: Arzoumanian Emmanuel , Vogel Felix R. , Bastos Ana , Gaynullin Bakhram , Laurent Olivier , Ramonet Michel , Ciais Philippe
Published: October 2018

Abstract. CO2 emission estimates from urban areas can be obtained with a network of in-situ instruments measuring atmospheric CO2 combined with high-resolution (inverse) transport modeling. The distribution of CO2 emissions being highly heterogeneous in space and variable in time in urban areas, gradients of atmospheric CO2 need to be measured by numerous instruments placed at multiple locations around and possibly within these urban areas, which calls for the development of lower-cost medium precision sensors to allow a deployment at required densities. Medium precision is here set to be a random error (uncertainty) on hourly measurements of ±1 ppm or less, a precision requirement based on previous studies of network design in urban areas. Here we present tests of a HPP commercial NDIR sensors manufactured by Senseair AB performed in the laboratory and at actual field stations, the latter for CO2 concentration in the Paris area. The lower-cost medium precision sensors are shown to be sensitive to atmospheric pressure and temperature conditions. The sensors respond linearly to CO2 when measuring calibration tanks, but the regression slope between measured and true CO2 differs between individual sensors and changes with time. In addition to pressure and temperature variations, humidity impacts the measurement of CO2, all causing systematic errors. In the field, an empirical calibration strategy is proposed based on parallel measurements with the lower-cost medium precision sensors and a high-precision instrument cavity ring-down instrument during 6 month. This empirical calibration method consists of using a multiple regression approach to create a model of the errors defined as the difference of CO2 measured by the lower-cost medium precision sensors relative to a calibrated high-precision instrument, based on predictors of air temperature, pressure and humidity. This error model shows good performances to explain the observed drifts of the lower-cost medium precision sensors on time scales of up to 1–2 months when trained against 1–2 weeks of high-precision instrument time series. Residual errors are contained within the ±1 ppm target, showing the feasibility to use networks of HPP instruments for urban CO2 networks, provided that they could be regularly calibrated against one anchor reference high-precision instrument.
Linking big models to big data: efficient ecosystem model calibration through Bayesian model emulation
Authors: Fer Istem , Kelly Ryan , Moorcroft Paul R. , Richardson Andrew D. , Cowdery Elizabeth M. , Dietze Michael C.
Published: October 2018

Abstract. Data-model integration plays a critical role in assessing and improving our capacity to predict ecosystem dynamics. Similarly, the ability to attach quantitative statements of uncertainty around model forecasts is crucial for model assessment and interpretation and for setting field research priorities. Bayesian methods provide a rigorous data assimilation framework for these applications, especially for problems with multiple data constraints. However, the Markov chain Monte Carlo (MCMC) techniques underlying most Bayesian calibration can be prohibitive for computationally demanding models and large datasets. We employ an alternative method, Bayesian model emulation of sufficient statistics, that can approximate the full joint posterior density, is more amenable to parallelization, and provides an estimate of parameter sensitivity. Analysis involved informative priors constructed from a meta-analysis of the primary literature and specification of both model and data uncertainties, and it introduced novel approaches to autocorrelation corrections on multiple data streams and emulating the sufficient statistics surface. We report the integration of this method within an ecological workflow management software, Predictive Ecosystem Analyzer (PEcAn), and its application and validation with two process-based terrestrial ecosystem models: SIPNET and ED2. In a test against a synthetic dataset, the emulator was able to retrieve the true parameter values. A comparison of the emulator approach to standard brute-force MCMC involving multiple data constraints showed that the emulator method was able to constrain the faster and simpler SIPNET model's parameters with comparable performance to the brute-force approach but reduced computation time by more than 2 orders of magnitude. The emulator was then applied to calibration of the ED2 model, whose complexity precludes standard (brute-force) Bayesian data assimilation techniques. Both models are constrained after assimilation of the observational data with the emulator method, reducing the uncertainty around their predictions. Performance metrics showed increased agreement between model predictions and data. Our study furthers efforts toward reducing model uncertainties, showing that the emulator method makes it possible to efficiently calibrate complex models.
Gas exchange estimates in the Peruvian upwelling regime biased by
multi-day near-surface stratification
Authors: Fischer Tim , Kock Annette , Arévalo-Martínez Damian L. , Dengler Marcus , Brandt Peter , Bange Hermann W.
Published: October 2018

Abstract. The coastal upwelling regime off Peru in December 2012 showed considerable concentration gradients of dissolved nitrous oxide (N2O) across the top few meters of the ocean. The gradients were predominantly downward, i.e. concentrations decreased toward the surface. Ignoring these gradients causes a systematic error in regionally integrated gas exchange estimates, when using observed concentrations at several meters below the surface as input for bulk flux parameterizations – as is routinely practiced. Here we propose that multi-day near-surface stratification events are responsible for the observed near-surface N2O gradients, and that the gradients induce the strongest bias in gas exchange estimates at winds of about 3 to 6 m/s. Glider hydrographic time series reveal that events of multi-day near-surface stratification are a common feature in the study region. In the same way as shorter events of near-surface stratification (e.g. the diurnal warm layer cycle), they preferentially exist under calm to moderate wind conditions, suppress turbulent mixing, and thus lead to isolation of the top layer from the waters below (surface trapping). Our observational data in combination with a simple gas-transfer model of the surface trapping mechanism show that multi-day near-surface stratification can produce near-surface N2O gradients comparable to observations. They further indicate that diurnal and shorter stratification cycles can only create N2O gradients that do not substantially impact emission estimates. Quantitatively, we estimate that the integrated bias for the entire Peruvian upwelling region in December 2012 represents an overestimation of the total N2O emission by about a third, if concentrations at 5 m or 10 m depth are used as surrogate for bulk water N2O concentration. Locally, gradients exist which would cause emission overestimations by a factor of two or more. As the Peruvian upwelling region is an N2O source of global importance, and other strong N2O source regions could tend to develop multi-day near-surface stratification as well, the bias resulting from multi-day near-surface stratification may also impact global oceanic N2O emission estimates.
Temperature seasonality in the North American continental interior during the Early Eocene Climatic Optimum
Authors: Hyland Ethan G. , Huntington Katharine W. , Sheldon Nathan D. , Reichgelt Tammo
Published: October 2018

Abstract. Paleogene greenhouse climate equability has long been a paradox in paleoclimate research. However, recent developments in proxy and modeling methods have suggested that strong seasonality may be a feature of at least some greenhouse Earth periods. Here we present the first multi-proxy record of seasonal temperatures during the Paleogene from paleofloras, paleosol geochemistry, and carbonate clumped isotope thermometry in the Green River Basin (Wyoming, USA). These combined temperature records allow for the reconstruction of past seasonality in the continental interior, which shows that temperatures were warmer in all seasons during the peak Early Eocene Climatic Optimum and that the mean annual range of temperatures was high, similar to the modern value ( ∼ 26 °C). Proxy data and downscaled Eocene regional climate model results suggest amplified seasonality during greenhouse events. Increased seasonality reconstructed for the early Eocene is similar in scope to the higher seasonal range predicted by downscaled climate model ensembles for future high-CO2 emissions scenarios. Overall, these data and model comparisons have substantial implications for understanding greenhouse climates in general, and may be important for predicting future seasonal climate regimes and their impacts in continental regions.
Reconciling North Atlantic climate modes: Revised monthly
indices for the East Atlantic and the Scandinavian patterns
beyond the 20th century
Authors: Comas-Bru Laia , Hernández Armand
Published: October 2018

Abstract. Climate variability in the North Atlantic sector is commonly ascribed to the North Atlantic Oscillation. However, recent studies have shown that taking into account the second and third mode of variability (namely the East Atlantic – EA – and the Scandinavian – SCA – patterns) greatly improves our understanding of their controlling mechanisms, as well as their impact on climate. The most commonly used EA and SCA indices span the period from 1950 to present which is too short, for example, to calibrate palaeoclimate records or assess their variability over multi-decadal scales. To tackle this, here, we create new EOF-based monthly EA and SCA indices covering the period from 1851 to present; and compare them with their equivalent instrumental indices. We also review and discuss the value of these new records and provide insights into the reasons why different sources of data may give slightly different time-series. Furthermore, we demonstrate that using these patterns to explain climate variability beyond the winter season needs to be done carefully due to their non-stationary behaviour. The datasets are available at https://doi.pangaea.de/10.1594/PANGAEA.892769.
Why has catchment evaporation increased in the past 40 years? A data-based study in Austria
Authors: Duethmann Doris , Blöschl Günter
Published: October 2018

Abstract. Regional evaporation has increased in many parts of the world in the last
decades, but the drivers of these increases are widely debated. Part of the
difficulty lies in the scarcity of high-quality long-term data on
evaporation. In this paper, we analyze changes in catchment evaporation
estimated from the water balances of 156 catchments in Austria over the
period 1977–2014 and attribute them to changes in atmospheric demand and
available energy, vegetation, and precipitation as possible drivers. Trend
analyses suggest that evaporation has significantly increased in 60 % of
the catchments (p≤0.05) with an average increase of
29±14 mm yr−1 decade−1 (± standard deviation) or
4.9±2.3 % decade−1. Pan evaporation based on 24 stations has, on
average, increased by 29±5 mm yr−1 decade−1 or
6.0±1.0 % decade−1. Reference evaporation over the 156 catchments
estimated by the Penman–Monteith equation has increased by
18±5 mm yr−1 decade−1 or 2.8±0.7 % decade−1. Of
these, 2.1 % are due to increased global radiation and 0.5 % due to
increased air temperature according to the Penman–Monteith equation. A
satellite-based vegetation index (NDVI) has increased by
0.02±0.01 decade−1 or 3.1±1.1 % decade−1. Estimates of
reference evaporation accounting for changes in stomata resistance due to
changes in the NDVI indicate that the increase in vegetation activity has led
to a similar increase in reference evaporation as changes in the climate
parameters. A regression between trends in evaporation and precipitation
yields a sensitivity of a 0.22±0.05 mm yr−2 increase in
evaporation to a 1 mm yr−2 increase in precipitation. A synthesis of
the data analyses suggests that 43±15 % of the observed increase in
catchment evaporation may be directly attributed to increased atmospheric
demand and available energy, 34±14 % to increased vegetation activity,
and 24±5 % to increases in precipitation.
Socio-hydrological spaces in the Jamuna River floodplain in Bangladesh
Authors: Ferdous Md Ruknul , Wesselink Anna , Brandimarte Luigia , Slager Kymo , Zwarteveen Margreet , Di Baldassarre Giuliano
Published: October 2018

Abstract. Socio-hydrology aims to understand the dynamics and co-evolution
of coupled human–water systems, with research consisting of generic models as
well as specific case studies. In this paper, we propose a concept to help
bridge the gap between these two types of socio-hydrological studies:
socio-hydrological spaces (SHSs). A socio-hydrological space is a geographical
area in a landscape. Its particular combination of hydrological and social
features gives rise to the emergence of distinct interactions and dynamics
(patterns) between society and water. Socio-hydrological research on
human–flood interactions has found two generic responses, “fight” or
“adapt”. Distilling the patterns resulting from these responses in case
studies provides a promising way to relate contextual specificities to the
generic patterns described by conceptual models. Through the use of SHSs,
different cases can be compared globally without aspiring to capturing them
in a formal model. We illustrate the use of SHS for the Jamuna floodplain,
Bangladesh. We use narratives and experiences of local experts and
inhabitants to empirically describe and delimit SHS. We corroborated the
resulting classification through the statistical analysis of primary data
collected for the purpose (household surveys and focus group discussions) and
secondary data (statistics, maps etc.). Our example of the use of SHSs shows
that the concept draws attention to how historical patterns in the
co-evolution of social behaviour, natural processes and technological
interventions give rise to different landscapes, different styles of living
and different ways of organising livelihoods. This provides a texture to the
more generic patterns generated by socio-hydrological models, promising to
make the resulting analysis more directly useful for decision makers. We
propose that the usefulness of this concept in other floodplains, and for
other socio-hydrological systems than floodplains, should be explored.
Communicating Disaster Risk? An Evaluation of the Availability and
Quality of Flood Maps
Authors: Henstra Daniel , Minano Andrea , Thistlethwaite Jason
Published: October 2018

Abstract. One of the key priorities for disaster risk reduction is to ensure decision-makers, stakeholders and the public understand their exposure to disaster risk, so that they take protective action. Flood maps are a potentially valuable tool for facilitating this understanding of flood risk, but previous research have found that they vary considerably in availability and quality. Using an evaluation framework comprising nine criteria grounded in existing scholarship, this study assessed the quality of flood maps available to the public in Canadian communities located in designated flood risk areas. It found that flood maps in most municipalities (62 %) are low-quality (meeting less than 50 % of the criteria) and the highest score was 78 % (7 of 9 criteria met). The findings suggest that a more concerted effort to produce high-quality, publicly-accessible flood maps is required to support Canada's international commitment to disaster risk reduction. Further questions surround possible weighting of quality assessment criteria, whether and how individuals seek out flood maps, and how flood risk information could be better communicated using modern technology.
Spatial variability in snow precipitation and accumulation in COSMO–WRF simulations and radar estimations over complex terrain
Authors: Gerber Franziska , Besic Nikola , Sharma Varun , Mott Rebecca , Daniels Megan , Gabella Marco , Berne Alexis , Germann Urs , Lehning Michael
Published: October 2018

Abstract. Snow distribution in complex alpine terrain and its evolution in
the future climate is important in a variety of applications including
hydropower, avalanche forecasting and freshwater resources. However, it is
still challenging to quantitatively forecast precipitation, especially over
complex terrain where the interaction between local wind and precipitation
fields strongly affects snow distribution at the mountain ridge scale.
Therefore, it is essential to retrieve high-resolution information about
precipitation processes over complex terrain. Here, we present very-high-resolution Weather Research and Forecasting model (WRF) simulations
(COSMO–WRF), which are initialized by 2.2 km resolution Consortium for
Small-scale Modeling (COSMO) analysis. To assess the ability of COSMO–WRF to
represent spatial snow precipitation patterns, they are validated against
operational weather radar measurements. Estimated COSMO–WRF precipitation is
generally higher than estimated radar precipitation, most likely due to an
overestimation of orographic precipitation enhancement in the model. The high
precipitation amounts also lead to a higher spatial variability in the model
compared to radar estimates. Overall, an autocorrelation and scale analysis
of radar and COSMO–WRF precipitation patterns at a horizontal grid spacing
of 450 m show that COSMO–WRF captures the spatial variability normalized by
the domain-wide variability in precipitation patterns down to the scale of a
few kilometers. However, simulated precipitation patterns systematically show
a lower variability on the smallest scales of a few hundred meters compared to radar
estimates. A comparison of spatial variability for different model
resolutions gives evidence for an improved representation of local
precipitation processes at a horizontal resolution of 50 m compared to
450 m. Additionally, differences of precipitation between 2830 m above sea
level and the ground indicate that near-surface processes are active in the
model.
An assessment of sub-snow GPS for quantification of snow water equivalent
Authors: Steiner Ladina , Meindl Michael , Fierz Charles , Geiger Alain
Published: October 2018

Abstract. Global Navigation Satellite Systems (GNSS) contribute to various
Earth observation applications. The present study investigates the potential
and limitations of the Global Positioning System (GPS) to estimate in situ
water equivalents of the snow cover (snow water equivalent, SWE) by using
buried GPS antennas. GPS-derived SWE is estimated over three seasons
(2015/16–2017/18) at a high Alpine test site in Switzerland. Results are
validated against state-of-the-art reference sensors: snow scale, snow
pillow, and manual observations. SWE is estimated with a high correspondence
to the reference sensors for all three seasons. Results agree with a median
relative bias below 10 % and are highly correlated to the mean of the three
reference sensors. The sensitivity of the SWE quantification is assessed for
different GPS ambiguity resolution techniques, as the results strongly depend
on the GPS processing.