bluuebunny/crossref_metadata_2025 huggingface dataset:
Potential of X-Band TerraSAR-X and COSMO-SkyMed SAR Data for the Assessment of Physical Soil Parameters
Authors: Gorrab Azza , Zribi Mehrez , Baghdadi Nicolas , Mougenot Bernard , Chabaane Zohra
Published: January 2015

The aim of this paper is to analyze the potential of X-band SAR measurements (COSMO-SkyMed and TerraSAR-X) made over bare soils for the estimation of soil moisture and surface geometry parameters at a semi-arid site in Tunisia (North Africa). Radar signals acquired with different configurations (HH and VV polarizations, incidence angles of 26° and 36°) are statistically compared with ground measurements (soil moisture and roughness parameters). The radar measurements are found to be highly sensitive to the various soil parameters of interest. A linear relationship is determined for the radar signals as a function of volumetric soil moisture, and a logarithmic correlation is observed between the radar signals and three surface roughness parameters: the root mean square height (Hrms), the parameter Zs = Hrms2/l (where l is the correlation length) and the parameter Zg = Hrms × (Hrms/l)α (where α is the power of the surface height correlation function). The highest dynamic sensitivity is observed for Zg at high incidence angles. Finally, the performance of different physical and semi-empirical backscattering models (IEM, Baghdadi-calibrated IEM and Dubois models) is compared with SAR measurements. The results provide an indication of the limits of validity of the IEM and Dubois models, for various radar configurations and roughness conditions. Considerable improvements in the IEM model performance are observed using the Baghdadi-calibrated version of this model.
A High Fuel Consumption Efficiency Management Scheme for PHEVs Using an Adaptive Genetic Algorithm
Authors: Lee Wah , Tsang Kim , Chi Hao , Hung Faan , Wu Chung , Chui Kwok , Lau Wing , Leung Yat
Published: January 2015

A high fuel efficiency management scheme for plug-in hybrid electric vehicles (PHEVs) has been developed. In order to achieve fuel consumption reduction, an adaptive genetic algorithm scheme has been designed to adaptively manage the energy resource usage. The objective function of the genetic algorithm is implemented by designing a fuzzy logic controller which closely monitors and resembles the driving conditions and environment of PHEVs, thus trading off between petrol versus electricity for optimal driving efficiency. Comparison between calculated results and publicized data shows that the achieved efficiency of the fuzzified genetic algorithm is better by 10% than existing schemes. The developed scheme, if fully adopted, would help reduce over 600 tons of CO2 emissions worldwide every day.
Received Signal Strength Recovery in Green WLAN Indoor Positioning System Using Singular Value Thresholding
Authors: Ma Lin , Xu Yubin
Published: January 2015

Green WLAN is a promising technique for accessing future indoor Internet services. It is designed not only for high-speed data communication purposes but also for energy efficiency. The basic strategy of green WLAN is that all the access points are not always powered on, but rather work on-demand. Though powering off idle access points does not affect data communication, a serious asymmetric matching problem will arise in a WLAN indoor positioning system due to the fact the received signal strength (RSS) readings from the available access points are different in their offline and online phases. This asymmetry problem will no doubt invalidate the fingerprint algorithm used to estimate the mobile device location. Therefore, in this paper we propose a green WLAN indoor positioning system, which can recover RSS readings and achieve good localization performance based on singular value thresholding (SVT) theory. By solving the nuclear norm minimization problem, SVT recovers not only the radio map, but also online RSS readings from a sparse matrix by sensing only a fraction of the RSS readings. We have implemented the method in our lab and evaluated its performances. The experimental results indicate the proposed system could recover the RSS readings and achieve good localization performance.
Development and Experimental Validation of a Numerical Tool for Structural Health and Usage Monitoring Systems Based on Chirped Grating Sensors
Authors: Bettini Paolo , Guerreschi Erika , Sala Giuseppe
Published: January 2015

The interest of the aerospace industries in structural health and usage monitoring systems is continuously increasing. Among the techniques available in literature those based on Fibre Bragg Grating sensors are much promising thanks to their peculiarities. Different Chirped Bragg Grating sensor configurations have been investigated in this paper. Starting from a numerical model capable of simulating the spectral response of a grating subjected to a generic strain profile (direct problem), a new code has been developed, allowing strain reconstruction from the experimental validation of the program, carried out through different loading cases applied on a chirped grating. The wavelength of the reflection spectrum for a chirped FBG has a one-to-one correspondence to the position along the gauge section, thus allowing strain reconstruction over the entire sensor length. Tests conducted on chirped FBGs also evidenced their potential for SHM applications, if coupled with appropriate numerical strain reconstructions tools. Finally, a new class of sensors—Draw Tower Grating arrays—has been studied. These sensors are applicable to distributed sensing and load reconstruction over large structures, thanks to their greater length. Three configurations have been evaluated, having different spatial and spectral characteristics, in order to explore possible applications of such sensors to SHM systems.
Frequency Noise Suppression of a Single Mode Laser with an Unbalanced Fiber Interferometer for Subnanometer Interferometry
Authors: Šmíd Radek , Čížek Martin , Mikel Břetislav , Číp Ondřej
Published: January 2015

We present a method of noise suppression of laser diodes by an unbalanced Michelson fiber interferometer. The unstabilized laser source is represented by compact planar waveguide external cavity laser module, ORIONTM (Redfern Integrated Optics, Inc.), working at 1540.57 nm with a 1.5-kHz linewidth. We built up the unbalanced Michelson interferometer with a 2.09 km-long arm based on the standard telecommunication single-mode fiber (SMF-28) spool to suppress the frequency noise by the servo-loop control by 20 dB to 40 dB within the Fourier frequency range, remaining the tuning range of the laser frequency.
Research on Rural Nonpoint Source Pollution in the Process of Urban-Rural Integration in the Economically-Developed Area in China Based on the Improved STIRPAT Model
Authors: Dai Hongjun , Sun Tao , Zhang Kun , Guo Wen
Published: January 2015

The process of urban-rural integration has led to severe ecological environmental pollution in rural areas of China, particularly in the economically-developed areas. This is an urgent issue to be solved. We select Jiangsu Province as a case study. From the perspective of the population, economic scale, energy consumption and financial support, we perform an empirical study of rural non-point source pollution problems in the process of urbanization based on the improved STIRPAT model. We apply the ridge regression method to avoid the multicollinearity of the variables in the STIRPAT model. The results show that the technological level, the size of the population and financial support are important factors affecting rural non-point source pollution. Therefore, we believe that technical progress, transformation of the mode of production and increasing the scale of financial support in rural areas are effective measures to solve the current rural nonpoint source pollution.
Acknowledgement to Reviewers of Viruses in 2014
Authors: Viruses Editorial Office
Published: January 2015

The editors of Viruses would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2014:[...]
Effects of Streambed Conductance on Stream Depletion
Authors: Lackey Greg , Neupauer Roseanna , Pitlick John
Published: January 2015

Stream depletion, which is the reduction in flow rate of a stream or river due to the extraction of groundwater in a hydraulically connected stream-aquifer system, is often estimated using numerical models. The accuracy of these models depends on the appropriate parameterization of aquifer and streambed hydraulic properties. Streambed conductance is a parameter that relates the head difference between the stream and aquifer to flow across the stream channel. It is a function of streambed hydraulic conductivity and streambed geometry. In natural systems, streambed conductance varies spatially throughout the streambed; however, stream depletion modeling studies often ignore this variability. In this work, we use numerical simulations to demonstrate that stream depletion estimates are sensitive to a range of streambed conductance values depending on aquifer properties. We compare the stream depletion estimates from various spatial patterns of streambed conductance to show that modeling streambed conductance as a homogeneous property can lead to errors in stream depletion estimates. We use the results to identify feasible locations for proposed pumping wells such that the stream depletion due to pumping from a well within this feasible region would not exceed a prescribed threshold value, and we show that incorrect assumptions of the magnitude and spatial variability of streambed conductance can affect the size and shape of the feasible region.
Managing Interoperability and Complexity in Health Systems
Authors: Tao C. , Sarkar I. N. , Bouamrane M. -M.
Published: January 2015

In recent years, we have witnessed substantial progress in the use of clinical informatics systems to support clinicians during episodes of care, manage specialised domain knowledge, perform complex clinical data analysis and improve the management of health organisations’ resources. However, the vision of fully integrated health information eco systems, which provide relevant information and useful knowledge at the point-of-care, remains elusive. This journal Focus Theme reviews some of the enduring challenges of interoperability and complexity in clinical informatics systems. Furthermore, a range of approaches are proposed in order to address, harness and resolve some of the many remaining issues towards a greater integration of health information systems and extraction of useful or new knowledge from heterogeneous electronic data repositories.
Anion effect controlling the selectivity in the zinc-catalysed copolymerisation of CO2 and cyclohexene oxide
Authors: Elmas Sait , Subhani Muhammad Afzal , Leitner Walter , Müller Thomas E
Published: January 2015

The choice of the anion has a surprisingly strong effect on the incorporation of CO2 into the polymer obtained during the zinc-catalysed copolymerisation of CO2 and cyclohexene oxide. The product span ranges from polyethercarbonates, where short polyether sequences alternate with carbonate linkages, to polycarbonates with a strictly alternating sequence of the repeating units. Herein, we report on the influence of the coordination ability of the anion on the selectivity and kinetics of the copolymerisation reaction.
Biological Diversity, Ecological Health and Condition of Aquatic Assemblages at National Wildlife Refuges in Southern Indiana, USA
Authors: Simon Thomas , Morris Charles , Robb Joseph , McCoy William
Published: January 2015

The National Wildlife Refuge system is a vital resource for the protection and conservation of biodiversity and biological integrity in the United States. Surveys were conducted to determine the spatial and temporal patterns of fish, macroinvertebrate, and crayfish populations in two watersheds that encompass three refuges in southern Indiana. The Patoka River National Wildlife Refuge had the highest number of aquatic species with 355 macroinvertebrate taxa, six crayfish species, and 82 fish species, while the Big Oaks National Wildlife Refuge had 163 macroinvertebrate taxa, seven crayfish species, and 37 fish species. The Muscatatuck National Wildlife Refuge had the lowest diversity of macroinvertebrates with 96 taxa and six crayfish species, while possessing the second highest fish species richness with 51 species. Habitat quality was highest in the Muscatatuck River drainage with increased amounts of forested habitats compared to the Patoka River drainage. Biological integrity of the three refuges ranked the Patoka NWR as the lowest biological integrity (mean IBI reach scores = 35 IBI points), while Big Oaks had the highest biological integrity (mean IBI reach score = 41 IBI points). The Muscatatuck NWR had a mean IBI reach score of 31 during June, which seasonally increased to a mean of 40 IBI points during summer. Watershed IBI scores and habitat condition were highest in the Big Oaks NWR.
MEDICAL IMAGE REGISTRATION BASED ON IMPROVED FUZZY C-MEANS CLUSTERING
Authors: Pan Meisen , Jiang Jianjun , Zhang Fen , Rong Qiusheng
Published: January 2015

The mutual information (MI) technology and the iterative closest point (ICP) algorithm, as intensity-based and feature-based image registration methods respectively, are commonly put into use in medical image registration. But some naturally existing things which restrict the further development need to be faced and be solved. On one hand, they remain heavy calculation costs and low registration efficiencies. On the other hand, since they seriously depend on whether the initial rotation and translation registration parameters can be exactly selected, they often trap in the local optima and even fail to register images. In this paper, we compute the centroids of the reference and floating images by using the image moments to obtain the initial translation values, and use improved fuzzy C-means clustering (IFCM) to classify the image coordinates. Before clustering, this proposed method first centralizes the medical image coordinates, creates the two-row coordinate matrix to construct the two-dimensional (2D) sample set partitioned into two classes, and computes the slope of a straight line fitted to the two classes, finally derives the rotation angle from solving the arc tangent of the slope and obtains the initial rotation values. The experimental results show that, this proposed method has a fairly simple implementation, a low computational load, a fast registration and good registration accuracy. Also, it can efficiently avoid trapping in the local optima and meets both mono-modality and multi-modality image registrations.
An Experimental Investigation of Ground Effect on a Quad Tilt Rotor in Hover
Authors: Mylapore Anand Radhakrishnan , Schmitz Fredric H.
Published: January 2015

The performance of a 0.031 geometrically scaled fuselage/wing model of a Quad Tilt Rotor (QTR) operating in helicopter mode while hovering in-ground effect (IGE) and out-of-ground effect (OGE) was experimentally studied. The effect of ground proximity was tested by varying the height
of the model above the ground. Measurements included download on the airframe; thrust, torque, and rpm of the rotors; and static pressures along the centerline of the bottom of the fuselage. Fixedpitch propellers were used to model the rotors. The downwash distributions of the rotors were
measured and compared well with large-scale V-22 rotor measurements. Tuft flow visualization was used to identify the physical processes causing changes in the download and static pressure measurements. The uncertainty of the measured quantities was determined to 95% confidence levels. A significant
download (9 ± 0.5% of the rotor thrust) was observed in hover, OGE. The download reduced substantially IGE and become an upload (8.5 ± 0.5% of the rotor thrust) when the wheels of the QTR were on the ground. Flow visualization and pressure measurements suggest that the upload
IGE is caused by the interaction of the wakes from the four rotors that are turned parallel to the ground and meet under the fuselage. The measured download, coupled with power measurements, indicate that for a given power the available vehicle thrust significantly increases IGE.
A Case of Successful Laparoscopic Surgery for Tubal Stump Pregnancy after Tubectomy
Authors: Nishida Masakazu , Miyamoto Yuko , Kawano Yasushi , Takebayashi Kanetoshi , Narahara Hisashi
Published: January 2015

The incidence of ectopic pregnancy is approximately 1.3∼2% of all pregnancies, and more than 90% of ectopic pregnancies are detected in the ampulla of the fallopian tube. Ectopic pregnancy occurring in tubal stump after tubectomy is extremely rare, and the frequency of tubal stump pregnancy is approximately 0.4% of all pregnancies. We report one of these rare cases of ectopic pregnancy in a 26-year-old Japanese woman, gravida 4, parity 1. She had undergone laparoscopic tubectomy because of a tubal pregnancy two years ago. She was presented to our hospital with a positive pregnancy test, but no gestational sac was detected in the uterus by echography, even though the level of human chorionic gonadotropin (hCG) in the blood was elevated to 8,900 mIU/mL. Laparoscopic surgery for ectopic pregnancy was performed. During surgery, the position of the pregnancy was found to be in the tubal stump, where tubectomy had already been performed, and the gestational sac was successfully removed. After the surgery, the condition of the patient uneventfully improved and she was discharged from the hospital three days after the surgery. The diagnosis of tubal stump pregnancy is more difficult than that of the more common positions of an ectopic pregnancy in the fallopian tube, and so it is more important to carefully examine the patients with suspected ectopic pregnancy. Laparoscopic surgery is one of the options for tubal stump pregnancy if diagnosed early and if the condition of the patient is stable.
Network-Constrained Group Lasso for High-Dimensional Multinomial Classification with Application to Cancer Subtype Prediction
Authors: Tian Xinyu , Wang Xuefeng , Chen Jun
Published: January 2015

Classic multinomial logit model, commonly used in multiclass regression problem, is restricted to few predictors and does not take into account the relationship among variables. It has limited use for genomic data, where the number of genomic features far exceeds the sample size. Genomic features such as gene expressions are usually related by an underlying biological network. Efficient use of the network information is important to improve classification performance as well as the biological interpretability. We proposed a multinomial logit model that is capable of addressing both the high dimensionality of predictors and the underlying network information. Group lasso was used to induce model sparsity, and a network-constraint was imposed to induce the smoothness of the coefficients with respect to the underlying network structure. To deal with the non-smoothness of the objective function in optimization, we developed a proximal gradient algorithm for efficient computation. The proposed model was compared to models with no prior structure information in both simulations and a problem of cancer subtype prediction with real TCGA (the cancer genome atlas) gene expression data. The network-constrained mode outperformed the traditional ones in both cases.
Доказательство Г. Шталя гипотезы БМВ
Authors: Eremenko Alexandre Emmanuilovich
Published: January 2015

Приведена упрощенная версия доказательства Г. Шталя гипотезы Бессиса-Муссы-Виллани о следах
матриц $A+tB$, где $A$ и $B$ эрмитовы.
Библиография: 5 названий.
Круговая симметризация конденсаторов на римановых поверхностях
Authors: Dubinin Vladimir Nikolaevich
Published: January 2015

Дается упрощенное определение новой версии круговой симметризации, предложенной ранее автором для решения экстремальных задач геометрической теории функций. Приводится доказательство принципа симметризации для емкостей конденсаторов, расположенных на римановых поверхностях. Более того,
расширяется класс рассматриваемых ранее конденсаторов и устанавливаются все случаи равенства в принципе симметризации.
Библиография: 22 названия.
Области Каратеодори и теорема Рудина об обращении принципа максимума модуля
Authors: Fedorovskiy Konstantin Yurievich
Published: January 2015

Получены результаты, распространяющие классическую теорему У. Рудина об обращении принципа максимума модуля с круга на области Каратеодори. Доказательства основаны на использовании недавних результатов о свойствах конформных отображений областей Каратеодори, которые также рассматриваются в работе.
Библиография: 18 названий.
Продолжения типа Рунге и Уолша гладких субгармонических функций на открытых римановых поверхностях
Authors: Boivin Andre , Gauthier Paul M , Paramonov Petr Vladimirovich
Published: January 2015

Изучается несколько постановок проблемы $C^m$-субгармонических продолжений на открытых римановых поверхностях. Эта проблема полностью решается (при всех $m\in[0,+\infty)$) для так называемых продолжений типа Рунге. Несколько (в определенном смысле точных) достаточных условий и контрпримеров найдено также для продолжений типа Уолша. В качестве приложений эти результаты позволяют доказать существование
$C^m$-субгармонических продолжений, автоморфных относительно некоторых подходящих групп автоморфизмов произвольной открытой римановой поверхности.
Библиография: 22 названия.
Pérdida estimada de bosque tropical seco en Carácuaro, Michoacán, México (2004-2012) a partir del análisis comparativo de imágenes SPOT
Authors: Zaragoza Peralta Leni , Mota Narváez Luis Alberto , España Boquera María Luisa , Champo Jiménez Omar , Gutiérrez Vázquez Ernestina
Published: January 2015

El bosque tropical seco (BTS) está sufriendo un rápido deterioro en el estado de Michoacán, México, por el pastoreo y la agricultura de temporal. El objetivo de este estudio fue analizar la pérdida del bosque tropical seco en el municipio de Carácuaro, Mich., entre 2004 y 2012, utilizando dos imágenes SPOT (10m). Se realizó una clasificación no supervisada de 20 clases de las imágenes preprocesadas y se calculó el NDVI promedio de cada clase. Las clases se reagruparon según rangos de NDVI en: vegetación de hoja perenne, de hoja caduca (BTS) y suelo. Las clasificaciones se validaron (95.5 %) con 2000 px/cobertura con imágenes pancromáticas SPOT (2.5m) de las mismas fechas. Se obtuvieron la matriz y el mapa de cambios. Éstos se produjeron en todo el municipio, afectando al 24.75 % de la superficie. En el periodo estudiado, el 18.73 % (13,926.59 ha) de la superficie de BTS sufrió algún tipo de cambio: el 14.3 % (10,665.13 ha) pasó a ser suelo y el resto vegetación de hoja perenne (probablemente arbustiva). Por otra parte, 5,290.52 ha de suelo se recuperaron como BTS, si bien se puede pensar que sufrieron una pérdida de biodiversidad.
Global investigation of the Mg atom and ion layers using SCIAMACHY/Envisat observations between 70 and 150 km altitude and WACCM-Mg model results
Authors: Langowski M. P. , von Savigny C. , Burrows J. P. , Feng W. , Plane J. M. C. , Marsh D. R. , Janches D. , Sinnhuber M. , Aikin A. C. , Liebing P.
Published: January 2015

Abstract. Mg and Mg+ concentration fields in the upper mesosphere/lower thermosphere (UMLT) region are retrieved from SCIAMACHY/Envisat limb measurements of Mg and Mg+ dayglow emissions using a 2-D tomographic retrieval approach. The time series of monthly mean Mg and Mg+ number density and vertical column density in different latitudinal regions are presented. Data from the limb mesosphere–thermosphere mode of SCIAMACHY/Envisat are used, which cover the 50 to 150 km altitude region with a vertical sampling of ≈3.3 km and latitudes up to 82°. The high latitudes are not observed in the winter months, because there is no dayglow emission during polar night. The measurements were performed every 14 days from mid-2008 until April 2012. Mg profiles show a peak at around 90 km altitude with a density between 750 cm−3 and 1500 cm−3. Mg does not show strong seasonal variation at latitudes below 40°. For higher latitudes the density is lower and only in the Northern Hemisphere a seasonal cycle with a summer minimum is observed. The Mg+ peak occurs 5–15 km above the neutral Mg peak altitude. These ions have a significant seasonal cycle with a summer maximum in both hemispheres at mid and high latitudes. The strongest seasonal variations of Mg+ are observed at latitudes between 20 and 40° and the density at the peak altitude ranges from 500 cm−3 to 4000 cm−3. The peak altitude of the ions shows a latitudinal dependence with a maximum at mid latitudes that is up to 10 km higher than the peak altitude at the equator. The SCIAMACHY measurements are compared to other measurements and WACCM model results. The WACCM results show a significant seasonal variability for Mg with a summer minimum, which is more clearly pronounced than for SCIAMACHY, and globally a higher peak density than the SCIAMACHY results. Although the peak density of both is not in agreement, the vertical column density agrees well, because SCIAMACHY and WACCM profiles have different widths. The agreement between SCIAMACHY and WACCM results is much better for Mg+ with both showing the same seasonality and similar peak density. However, there are also minor differences, e.g. WACCM showing a nearly constant altitude of the Mg+ layer's peak density for all latitudes and seasons.
Investigating the discrepancy between wet-suspension and dry-dispersion derived ice nucleation efficiency of mineral particles
Authors: Emersic C. , J. Connolly P. , Boult S. , Campana M. , Li Z.
Published: January 2015

Abstract. Cloud chamber investigations into ice nucleation by mineral particles were compared with results from cold stage droplet freezing experiments. Kaolinite, NX-illite, and K-feldspar were examined and K-feldspar was revealed to be the most ice active mineral particle sample, in agreement with recent cold stage studies. The ice nucleation efficiencies, as quantified using the ice active site density method, were found to be in agreement with previous studies for the lower temperatures; however, at higher temperatures the efficiency was consistently higher than those inferred from cold stage experiments. Numerical process modelling of cloud formation during the experiments, using the cold-stage-derived parameterisations to initiate the ice phase, revealed the cold-stage-derived parameterisations to consistently under predict the number of ice crystals relative to that observed. We suggest the reason for the underestimation of ice in the model is that the slope of the cold-stage-derived ice active site density vs temperature curves are too steep, which results in an underestimation of the number of ice crystals at higher temperatures during the expansion. These ice crystals suppress further freezing due to the Bergeron-Findeison process. Application of a coagulation model to the size distribution of mineral particles present in the suspensions as used in the cold-stage-derived parameterisations revealed that it is likely that the mineral particles coagulate in suspension, which either removes the particles from the drops by sedimentation or reduces the total particle surface area available for ice nucleation to take place. This is confirmed with measurements of colloidal suspensions. The implication is that the mineral particles may be more important than previously thought at high temperatures.
Chemical characterization of submicron regional background aerosols in the Western Mediterranean using an Aerosol Chemical Speciation Monitor
Authors: Minguillón M. C. , Ripoll A. , Pérez N. , Prévôt A. S. H. , Canonaco F. , Querol X. , Alastuey A.
Published: January 2015

Abstract. An Aerosol Chemical Speciation Monitor (ACSM, Aerodyne Research Inc.) was deployed at Montseny (MSY, 720 m a.s.l.) regional background site in the Western Mediterranean from June 2012 to July 2013 to measure real-time inorganic (nitrate, sulphate, ammonium and chloride) and organic submicron aerosol concentrations. Co-located measurements were also carried out including real-time submicron particulate matter (PM1) and black carbon (BC) concentrations, and off-line PM1 chemical analysis. This is one of the few studies that compare ACSM data with off-line PM1 measurements, avoiding the tail of the coarse mode included in the PM2.5 fraction. The ACSM + BC concentrations agreed with the PM1 measurements, and strong correlation was found between the concentrations of ACSM species and the off-line measurements, although some discrepancies remain unexplained. Results point to a current underestimation of the relative ionization efficiency (RIE) established for organic aerosol (OA), which should be revised in the future. The OA was the major component of submicron aerosol (53% of PM1), with a higher contribution in summer (58% of PM1) than in winter (45% of PM1). Source apportionment of OA was carried out by applying Positive Matrix Factorization (PMF) using the Multilinear Engine (ME-2) to the organic mass spectral data matrix. Three sources were identified in summer: hydrocarbon-like OA (HOA), low-volatile oxygenated OA (LV-OOA), and semi-volatile oxygenated OA (SV-OOA). The secondary OA (SOA, 4.7 μg m−3, sum of LV-OOA and SV-OOA) accounted for 85% of the total OA and its formation during daytime (mainly SV-OOA) was estimated to be 1.1 μg m−3. In winter, HOA was also identified (12% of OA), a contribution from biomass burning OA was included, and it was not possible to differentiate two different SOA factors but a single OOA factor was resolved. The OOA contribution represented the 60% of the total OA, with a degree of oxidation higher than both OOA summer factors. An intense wildfire episode was studied obtaining a region-specific BBOA profile.
Detecting and locating seismic events with using USArray as a large antenna
Authors: Retailleau L. , Shapiro N. M. , Guilbert J. , Campillo M. , Roux P.
Published: January 2015

Abstract. We design an earthquake detection and location algorithm that explores coherence and characteristic behavior of teleseismic waves recorded by a large-scale seismic network. The procedure consists of three steps. First, for every tested source location we construct a time-distance gather by computing great-circle distances to all stations of the network and aligning the signals respectively. Second, we use the constructed gather to compute a Tau-P transform. For waves emitted by teleseismic sources, the amplitude of this transform has a very characteristic behavior with maxima corresponding to different seismic phases. Relative location of these maxima on the time-slowness plane strongly depends on the distance to the earthquake. To explore this dependence, in a third step, we convolve the Tau-P amplitude with a time-slowness filter whose maxima are computed based on prediction of a global travel-time calculator. As a result of this three-step procedure, we obtain a function that characterizes a likelihood of occurrence of a seismic event at a given position in space and time. We test the developed algorithm by applying it to vertical-component records of USArray to locate a set of earthquakes distributed around the Globe with magnitudes between 6.1 and 7.2.
Using digital image processing to characterize the Campbell–Stokes sunshine recorder and to derive high-temporal resolution direct solar irradiance
Authors: Sanchez-Romero A. , González J. A. , Calbó J. , Sanchez-Lorenzo A.
Published: January 2015

Abstract. The Campbell–Stokes sunshine recorder (CSSR) has been one of the most commonly used instruments for measuring sunshine duration (SD) through the burn length of a given CSSR card. Many authors have used SD to obtain information about cloudiness and solar radiation (by using Ångström–Prescott type formulas), but the burn width has not been used systematically. In principle, the burn width increases for increasing direct beam irradiance. The aim of this research is to show the relationship between burn width and direct solar irradiance (DSI) and to prove whether this relationship depends on the type of CSSR and burning card. A method of analysis based on image processing of digital scanned images of burned cards is used. With this method, the temporal evolution of the burn width with 1 min resolution can be obtained. From this, SD is easily calculated and compared with the traditional (i.e., visual) determination. The method tends to slightly overestimate SD, but the thresholds that are used in the image processing could be adjusted to obtain an improved estimation. Regarding the burn width, experimental results show that there is a high correlation between two different models of CSSRs, as well as a strong relationship between burn widths and DSI at a high-temporal resolution. Thus, for example, hourly DSI may be estimated from the burn width with higher accuracy than based on burn length (for one of the CSSR, relative root mean squared error is 24 and 30%, respectively; mean bias error is −0.6 and −30.0 W m−2, respectively). The method offers a practical way to exploit long-term sets of CSSR cards to create long time series of DSI. Since DSI is affected by atmospheric aerosol content, CSSR records may also become a proxy measurement for turbidity and atmospheric aerosol loading.
A two-channel, tunable diode laser-based hygrometer for measurement of water vapor and cirrus cloud ice water content in the upper troposphere and lower stratosphere
Authors: Thornberry T. D. , Rollins A. W. , Gao R. S. , Watts L. A. , Ciciora S. J. , McLaughlin R. J. , Fahey D. W.
Published: January 2015

Abstract. The recently developed NOAA Water instrument is a two-channel, closed-path, tunable diode laser absorption spectrometer designed for the measurement of upper troposphere/lower stratosphere water vapor and enhanced total water (vapor + inertially enhanced condensed phase) from the NASA Global Hawk unmanned aircraft system (UAS) or other high-altitude research aircraft. The instrument utilizes wavelength-modulated spectroscopy with second harmonic detection near 2694 nm to achieve high precision with a 79 cm double-pass optical path. The detection cells are operated under constant temperature, pressure, and flow conditions to maintain a constant sensitivity to H2O independent of the ambient sampling environment. An onboard calibration system is used to perform periodic in situ calibrations to verify the stability of the instrument sensitivity during flight. For the water vapor channel, ambient air is sampled perpendicular to the flow past the aircraft in order to reject cloud particles, while the total water channel uses a heated, forward-facing inlet to sample both water vapor and cloud particles. The total water inlet operates subisokinetically, thereby inertially enhancing cloud particle number in the sample flow and affording increased cloud water content sensitivity. The NOAA Water instrument was flown for the first time during the second deployment of the Airborne Tropical TRopopause EXperiment (ATTREX) in February–March 2013 on the NASA Global Hawk UAS. The instrument demonstrated a typical in-flight precision (1 s, 1σ) of better than 0.17 parts per million (ppm, 10−6 mol mol−1), with an overall H2O vapor measurement uncertainty of 5% ± 0.23 ppm. The inertial enhancement for cirrus cloud particle sampling under ATTREX flight conditions ranged from 33 to 48 for ice particles larger than 8 μm in diameter, depending primarily on aircraft altitude. The resulting ice water content detection limit (2σ) was 0.023–0.013 ppm, corresponding to approximately 2 μg m−3, with an estimated overall uncertainty of 20%.
Case study on complex sporadic E layers observed by GPS radio occultations
Authors: Yue X. , Schreiner W. S. , Zeng Z. , Kuo Y.-H. , Xue X.
Published: January 2015

Abstract. The occurrence of sporadic E (Es) layers has been a hot scientific topic for a long time. The GNSS (global navigation satellite system)-based radio occultation (RO) has proven to be a powerful technique for detecting the global Es layers. In this paper, we focus on some cases of complex Es layers based on the RO data from multiple missions processed in UCAR/CDAAC (University Corporation for Atmospheric Research (UCAR) the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) Data Analysis and Archive Center (CDAAC)). We first show some examples of multiple Es layers occurred in one RO event. Based on the evaluations between colocated simultaneous RO events and between RO and lidar observations, it could be concluded that some of these do manifest the multiple Es layer structures. We then show a case of the occurrence of Es in a broad region during a certain time interval. The result is then validated by independent ionosondes observations. It is possible to explain these complex Es structures using the popular wind shear theory. We could map the global Es occurrence routinely in the near future, given that more RO data will be available. Further statistical studies will enhance our understanding of the Es mechanism. The understanding of Es should benefit both Es-based long-distance communication and accurate neutral RO retrievals.
A depolarisation lidar-based method for the determination of liquid-cloud microphysical properties
Authors: Donovan D. P. , Klein Baltink H. , Henzing J. S. , de Roode S. R. , Siebesma A. P.
Published: January 2015

Abstract. The fact that polarisation lidars measure a depolarisation signal in liquid clouds due to the occurrence of multiple scattering is well known. The degree of measured depolarisation depends on the lidar characteristics (e.g. wavelength and receiver field of view) as well as the cloud macrophysical (e.g. cloud-base altitude) and microphysical (e.g. effective radius, liquid water content) properties. Efforts seeking to use depolarisation information in a quantitative manner to retrieve cloud properties have been undertaken with, arguably, limited practical success. In this work we present a retrieval procedure applicable to clouds with (quasi-)linear liquid water content (LWC) profiles and (quasi-)constant cloud-droplet number density in the cloud-base region. Thus limiting the applicability of the procedure allows us to reduce the cloud variables to two parameters (namely the derivative of the liquid water content with height and the extinction at a fixed distance above cloud base). This simplification, in turn, allows us to employ a fast and robust optimal-estimation inversion using pre-computed look-up tables produced using extensive lidar Monte Carlo (MC) multiple-scattering simulations. In this paper, we describe the theory behind the inversion procedure and successfully apply it to simulated observations based on large-eddy simulation (LES) model output. The inversion procedure is then applied to actual depolarisation lidar data corresponding to a range of cases taken from the Cabauw measurement site in the central Netherlands. The lidar results were then used to predict the corresponding cloud-base region radar reflectivities. In non-drizzling condition, it was found that the lidar inversion results can be used to predict the observed radar reflectivities with an accuracy within the radar calibration uncertainty (2–3 dBZ). This result strongly supports the accuracy of the lidar inversion results. Results of a comparison between ground-based aerosol number concentration and lidar-derived cloud-droplet number densities are also presented and discussed. The observed relationship between the two quantities is seen to be consistent with the results of previous studies based on aircraft-based in situ measurements.
Evaluating the ocean biogeochemical components of Earth system models using atmospheric potential oxygen and ocean color data
Authors: Nevison C. D. , Manizza M. , Keeling R. F. , Kahru M. , Bopp L. , Dunne J. , Tiputra J. , Ilyina T. , Mitchell B. G.
Published: January 2015

Abstract. The observed seasonal cycles in atmospheric potential oxygen (APO) at a range of mid- to high-latitude surface monitoring sites are compared to those inferred from the output of six Earth system models (ESMs) participating in the fifth phase of the Coupled Model Intercomparison Project phase 5 (CMIP5). The simulated air–sea O2 fluxes are translated into APO seasonal cycles using a matrix method that takes into account atmospheric transport model (ATM) uncertainty among 13 different ATMs. Three of the ocean biogeochemistry models tested are able to reproduce the observed APO cycles at most sites, to within the large TransCom3-era ATM uncertainty used here, while the other three generally are not. Net primary production (NPP) and net community production (NCP), as estimated from satellite ocean color data, provide additional constraints, albeit more with respect to the seasonal phasing of ocean model productivity than overall magnitude. The present analysis suggests that, of the tested ocean biogeochemistry models, the community ecosystem model (CESM) and the Geophysical Fluid Dynamics Laboratory (GFDL) ESM2M are best able to capture the observed APO seasonal cycle at both northern and southern hemispheric sites. In most models, discrepancies with observed APO can be attributed to the underestimation of NPP, deep ventilation or both in the northern oceans.
Variable C : N : P stoichiometry of dissolved organic matter cycling in the Community Earth System Model
Authors: Letscher R. T. , Moore J. K. , Teng Y.-C. , Primeau F.
Published: January 2015

Abstract. Dissolved organic matter (DOM) plays an important role in the ocean's biological carbon pump by providing an advective/mixing pathway for ~ 20% of export production. DOM is known to have a stoichiometry depleted in nitrogen (N) and phosphorus (P) compared to the particulate organic matter pool, a fact that is often omitted from biogeochemical ocean general circulation models. However the variable C : N : P stoichiometry of DOM becomes important when quantifying carbon export from the upper ocean and linking the nutrient cycles of N and P with that of carbon. Here we utilize recent advances in DOM observational data coverage and offline tracer-modeling techniques to objectively constrain the variable production and remineralization rates of the DOM C : N : P pools in a simple biogeochemical-ocean model of DOM cycling. The optimized DOM cycling parameters are then incorporated within the Biogeochemical Elemental Cycling (BEC) component of the Community Earth System Model (CESM) and validated against the compilation of marine DOM observations. The optimized BEC simulation including variable DOM C : N : P cycling was found to better reproduce the observed DOM spatial gradients than simulations that used the canonical Redfield ratio. Global annual average export of dissolved organic C, N, and P below 100 m was found to be 2.28 Pg C yr−1 (143 Tmol C yr−1, 16.4 Tmol N yr−1, and 1 Tmol P yr−1, respectively, with an average export C : N : P stoichiometry of 225 : 19 : 1 for the semilabile (degradable) DOM pool. Dissolved organic carbon (DOC) export contributed ~ 25% of the combined organic C export to depths greater than 100 m.
Nutrient and mercury deposition and storage in an alpine snowpack of the Sierra Nevada, USA
Authors: Pearson C. , Schumer R. , Trustman B. D. , Rittger K. , Johnson D. W. , Obrist D.
Published: January 2015

Abstract. Bi-weekly snowpack core samples were collected at seven sites along two elevation gradients in the Tahoe Basin during two consecutive snow years to evaluate total wintertime snowpack accumulation of nutrients and pollutants in a high elevation watershed of the Sierra Nevada. Additional sampling of wet deposition and detailed snow pit profiles was conducted the following year to compare wet deposition to snowpack storage and assess the vertical dynamics of snowpack chemicals. Results show that on average organic N comprised 48% of all snowpack N, while nitrate (NO3--N) and TAN (total ammonia nitrogen) made up 25 and 27%, respectively. Snowpack NO3--N concentrations were relatively uniform across sampling sites over the sampling seasons and showed little difference between seasonal wet deposition and integrated snow pit concentrations in agreement with previous studies that identify wet deposition as the dominant source of wintertime NO3--N deposition. However, vertical snow pit profiles showed highly variable concentrations of NO3--N within the snowpack indicative of additional deposition and in snowpack dynamics. Unlike NO3--N, snowpack TAN doubled towards the end of winter and in addition to wet deposition, had a strong dry deposition component. Organic N concentrations in snowpack were highly variable (from 35 to 70%) and showed no clear temporal or spatial dependence throughout the season. Integrated snowpack organic N concentrations were up to 2.5 times higher than seasonal wet deposition, likely due to microbial immobilization of inorganic N as evident by coinciding increases of organic N and decreases of inorganic N, in deeper, aged snowpack. Spatial and temporal deposition patterns of snowpack P were consistent with particulate-bound dry deposition inputs and strong impacts from in-basin sources causing up to 6 times enrichment at urban locations compared to remote sites. Snowpack Hg showed little temporal variability and was dominated by particulate-bound forms (78% on average). Dissolved Hg concentrations were consistently lower in snowpack than in wet deposition which we attribute to photochemical-driven gaseous remission. In agreement with this pattern is a significant positive relationship between snowpack Hg and elevation, attributed to a combination of increased snow accumulation at higher elevations causing limited light penetration and lower photochemical re-emission losses in deeper, higher elevation snowpack. Finally, estimates of basin-wide loading based on spatially extrapolated concentrations and a satellite-based snow water equivalent reconstruction model identify snowpack chemical loading from atmospheric deposition as a substantial source of nutrients and pollutants to the Lake Tahoe basin, accounting for 113 t of N, 9.3 t of P, and 1.2 kg of Hg each year.
GDGT distributions in the East Siberian Sea: implications for organic carbon export, burial and degradation
Authors: Sparkes R. B. , Doğrul Selver A. , Bischoff J. , Talbot H. M. , Gustafsson Ö. , Semiletov I. P. , Dudarev O. V. , van Dongen B. E.
Published: January 2015

Abstract. Siberian permafrost contains a globally-significant pool of organic carbon (OC) that is vulnerable to enhanced warming and subsequent release into the contemporary carbon cycle. OC release by both fluvial and coastal erosion has been reported in the region, but the behaviour of this material in the Arctic Ocean is insufficiently understood. The balance between OC deposition and degradation on the East Siberian Arctic Shelf (ESAS) influences the climate-carbon cycle feedback in this area. In this study we couple measurements of glycerol dialkyl glycerol tetraethers (GDGTs) with bulk geochemical observations to improve knowledge of the sources of OC to the ESAS, the behaviour of specific biomarkers on the shelf and the balance between delivery and removal of different carbon pools. Branched GDGT (brGDGT) concentrations were highest close to river mouths, yet low in "Yedoma" permafrost deposits, supporting recent observations that brGDGTs are mostly delivered by fluvial erosion, and may be a tracer for this in complex sedimentary environments. BrGDGT concentrations and the Branched and Isoprenoidal Tetraether (BIT) index reduced quickly offshore, demonstrating a rapid reduction in river influence. Stable carbon isotope ratios changed at a different rate to the BIT index, suggesting that OC on the shelf is not only sourced from fluvial erosion, but that erosion of coastal sediments delivers substantial quantities of OC to the Arctic Ocean. A model of OC export from fluvial, coastal and marine sources is able to recreate the biomarker and bulk observations and provide estimates for the influence of fluvial and coastal OC across the whole shelf. The model shows that coastal erosion delivers 43% of the OC and 87% of the mineral sediment to the ESAS, but that rivers deliver 72% of brGDGTs, indicating that brGDGTs can be used as a proxy for river-derived sediment.