bluuebunny/crossref_metadata_2025 huggingface dataset:
Parameterized Drawing Design of Drum Used in a Transformer Elevated Seat
Authors: Fu Chun Hua
Published: June 2014

Using LISP language embed in AutoCAD, the parametric drawing design for expanded view of the transformer elevated seat is discussed. The mathematical model is constructed and gotten solution with parameters comes from dialog built by OpenDCL. Weld is put to the position not easy to see. It is to increase the efficiency of design the expanded view of the transformer elevated seat. This method is worth widely spreading.
Residential Building Sound Pollution and Control Measures
Authors: Xu Nan , Zhang Chi , Ma Li
Published: June 2014

Noise of building life, residential areas environmental equipment and residential district external seriously interferes with the normal life of the residents, the sources and the mechanism of noise generation are analyzed, technical measures of multi family residential building noise are put forward.
Dynamics Simulation Analysis of an Airborne Electronic Equipment Based on Ansys and Modal Test
Authors: Wang Kai Shan , Li Chuan Ri , Pang Yue Chan , Guo Heng Hu
Published: June 2014

In order to conduct dynamics simulation analysis on an airborne electronic equipment, total mass equivalent method is used to simplify the finite element model of electronic building brick. Considering this method’s disadvantage that it does not take into account the effect which the components have on stiffness of the printed circuit board(PCB), the modal test technique is carried out to recify the model and generate the equivalent stiffness of the substrate. Then the modal analysis and random vibration analysis are performed on the complete machine, calculating more accurate dynamics simulation results which provide a reliable qualitative basis for improving the vibration-proof design of the equipment.
Study on the Combustion Noise Characteristic of Low Speed Diesel Engine
Authors: Yan Li Qi , Ge Hui Jun
Published: June 2014

In recent years, the Low speed two stroke diesel engines are widely used as the main power device of big ship for its so many advantages such as the high power, better economical efficiency and good maintenance. However, the problem of diesel strong vibration and noise becomes a more and more serious at the same time. Because of the Construction Features of marine two-stroke low-speed diesel engine, the structure has to be suffered different kind of forces when it runs. In considering the source of vibration, the whole noise can be divided into combustion noise、machinery noise and aerodynamic noise. The combustion noise caused by cylinder pressure is the most important part of diesel noise. In this paper, the cylinder pressure curves are tested. The internal combustion engine dynamics and the equivalent node load are used in the calculation procedure to achieve the real condition simulation. The loading program is made to simulate the change of cylinder pressure and the move of piston. The transient response of the diesel engine is calculated. The characteristics of diesel caused by cylinder pressure are analyzed.The response analysis can be used to the vibration control.
The Analysis of Self-Excited Vibration in Processing System of Single Blade Rigid Boring Reamer
Authors: Dong Zhen , Shen Xing Quan
Published: June 2014

The reaming process with rigid single blade reamers boring is one kind of deep processing methods which develop rapidly in recent years,which has a series of advantages such as high-speed cutting, auto-oriented, low surface roughness and so on.Appear as one kind of precision hole processing technology in the deep hole processing currently,and shows the superiority of processing.The self-excited vibration is a common phenomenon in deep processing,and seriously affect the stability of hole machining and processing quality.It performance very obvious in rigid single blade reamers boring processing,and has a certain degree of particularity. Established as a mathematical model of the rigid boring reamerThe analysis of mechanism of Self-excited vibration in reaming processing of single blade rigid boring reamer, and the study the impact of the friction characteristics of the guide block and the hole in self-excited vibrations,provide the basis for the inhibition of self-excited vibration.
Research on Tail Pipe for Engine Performance and Exhaust Noise
Authors: Yuan Shou Li , Zhang Chao
Published: June 2014

The whole engine model，including intake system, coupling with exhaust system, is established by the software GT-POWER. Through the parameter change of tail pipe geometry, it is analyzed in this paper how the tail pipe geometry affect tail pipe noise. With the test data and the simulation calculation results, it analyses the influence of the tail exhaust pipe length, diameter, shape, terminal bending angle on engine performance and tail pipe noise, so as to choose suitable design parameter of tail pipe to meet the requirements of engine performance and the tail pipe noise.
Study on Bending, Buckling and Free Vibration of Hard-Core Sandwich Plate Based on Revising the Soft-Core Reissner Theory
Authors: Zeng Hai Yan , Yan Ren Jun , Hu Yao Yu
Published: June 2014

The use of sandwich structures in various engineering fields is growing rapidly because of advantageous features such as low weight and high strength-to-weight ratio.The existing theories are all based on soft core assumption. In this case, the in-plane stress and the stiffness of the core are not included. It has been shown that Ressiner theory is inadequate for the analysis of hard-core sandwich plates. Different revision factors were put forward in this paper to revise the bending, buckling and free vibration results of soft-core Reissner theory for hard-core sandwich plates. The results show that the revised results go well with the hard core theory, so that its validity is confirmed.
Kinematics Analysis on Planar Gear Transmission Mechanism with Computer
Authors: Sun Jin Feng , Zhu Yong Zhang , Wang Jun , Wang Quan
Published: June 2014

Kinematics analysis is important to analyse and design planar gear transmission mechanism. Planar gear transmission mechanism is composed of two basic loop units. The kinematics analysis equation of the basic loop units is established based on the constituent characteristics of planar gear transmission mechanism and the motion relationship of every component in each basic loop unit. The kinematics analysis mathematical model of planar gear transmission mechanism is constructed by using the basic loop group units of planar gear transmission mechanism. With Windows XP as the platform, Visual Basic 6.0 as a tool and object-oriented programming method, a set of common software has been developed for kinematics analysis on planar gear transmission mechanism. The software has many advantages, such as simple operation, strong man-machine interaction, friendly interface and strong commonality.
The Development and Application of Grab Design System Based on Solidworks and CBR
Authors: Sun Yuan Tao , Zhang Ling Dong , Qin Xian Rong
Published: June 2014

Due to the diversity of bulk cargo, different capacity of throughput and complexity of environmental requirements, different grabs need to be designed rapidly to meet demands of users. However, current grab design is inefficiency and relies on experience of designers because there are still no mature and agreed specifications. Together with the design ideas, experience and standards, grab virtual design system, which is the output of secondary development on the basis of common mechanical CAD system by using virtual design theory, is developed and applied to devise new grab. Its application has shortened the design cycle and improved the design efficiency.
The Analysis of the Transmission Scheme of the 9 Speed Automatic Transmission Based on the Expend Lever Method
Authors: You Ming Fu , Hou Guo Qiang , Wang Meng Yao
Published: June 2014

First analylzes the ZF-9HP Automatic Transmission gears dynamic route and establish the equivalent lever diagram of ZF-9HP Automatic Transmission. Then analylzes the shift process of ZF-9HP Automatic Transmission based on the expend method of existing method of leverage, and verify the new lever method is correct by calculation.
The Study on Dynamic Modeling of Complex Mechanism Based on Multi Software Collaboration
Authors: Ma Chang Lin , Li Feng , Feng Yong Bao , Yao Xiao Guang
Published: June 2014

At present, the accurate dynamic modeling and simulation of complex movement mechanism using a single software is a difficult problem. The paper proposes the "collaborative simulation run" method of multi-domain model based on the interfaces of multi simulation software, and it can achieve the design and analysis of complex mechanism system. Selecting the 3D modeling software Pro/E, the dynamics analysis software ADAMS and finite element analysis software ANSYS as a collaborative modeling analysis platform, the transmission relationship between software data interfaces is studied, and the rigid flexible coupling dynamic modeling process of complex mechanism through the Pro/E, ANSYS and ADAMS is explored, which prepares accurate model for dynamic simulation of complex mechanism. The study results show that the multi-software collaborative modeling method is suitable for complex mechanical dynamics modeling.
Flow Filed Simulation Analysis and Structural Optimization of Automotive Catalytic Converter
Authors: Sui Tian Zhong , Wang Lei , Wang Yang
Published: June 2014

Catalytic converter is an important device of automobile engine exhaust system. Based on Hydromechanics, the relational mathematical models of catalytic converter simulation are established and the parameters are calculated. Making use of CFD numerical simulation method, a simulation is set up for the internal flow field of catalytic converter original model using fluent software. From the simulation, the internal flow characteristic is understood. On the basis of this, through the optimization idea adding a guiding device in inlet cone of catalytic converter, the uniformity of velocity of flow is improved. The simulation analysis show that the flow uniformity for internal flow field can be improved observably in the structural optimization, the increasing degree of pressure loss is with little range. A new idea and reference may be offered for improving flow uniformity of a catalytic converter.
Molecular Dynamics of the Flow Properties of Liquids in Wedge Nanochannel
Authors: Jia Yan , Shen Yu
Published: June 2014

Molecular dynamics method is applied to study the influence of velocity on the properties of fluid film in wedge nanochannel. Studies have shown that: in wedge nanochannel the impact of velocity of solid wall on the maximum pressure in the simulation region is limitation. After the pressure in the simulation region reaches the maximum, it is not increase with the velocity of lower solid wall rising. Due to molecules accumulation the average number of molecules in the simulation region enhance with the velocity of solid wall rising.
A CFD Study on Cavitating Flow in High-Speed Centrifugal Pumps under Low Flow Rates
Authors: Yuan Jian Ping , Zhu Yu Wen , Ge Ai Xiang
Published: June 2014

Cavitation is one of the most important aspects that need to be considered while designing centrifugal pumps, since it is a major contributor to failure and inefficiency. In order to study the cavitating performance in high-speed centrifugal pumps under low flow rates, the pump named IN-32-32-100 with two different impellers was investigated based on numerical and experimental methods. The impeller case 1 is the impeller with six blades. The impeller case 2 is the impeller with four long and four splitter blades. The research results show that the cavities of two impellers occur at the impeller inlet. The region of developed cavities extends and the volume fraction in the blade passages gradually increases with the decrease of inlet total pressure at the flow rate of 0.5Qd. The cavities distribute asymmetrically in each blade passage and the vapor fraction of one blade passage is significantly larger compared with them of blade passages. The inner flow of the pump can be effectively improved with more uniform pressure distribution by applying splitter blades. The critical cavitation number of the impeller case 1 and impeller case 2 corresponding to the sudden head-drop point are 3.2m and 3.55m, respectively. Compared with impeller case 2, cavitating performance of the pump with impeller case 1 is better. The numerical results agree well with the experimental data, which shows that the numerical method in the present study can to some extent accurately predict the cavitating development inside the high-speed centrifugal pump.
Experimental Study of Hydraulic Flip Phenomenon inside Diesel Nozzles Using Diesel and Biodiesel
Authors: Shao Zhuang , He Zhi Xia , Zhou Zhi Wei , Tao Xi Cheng
Published: June 2014

As cavitation inside diesel nozzles can improve the spray characteristics, it has long been a hot issue. And together with the increasing attention of biodiesel, it is essential to identify the difference of cavitating flow characteristics between diesel and biodiesel. What’s more, the hydraulic flip phenomenon and cavitating flow with decreasing injection pressure hasn’t been studied. Based on this, cavitating flow inside transparent nozzles of diesel and biodiesel fuels with increasing and decreasing injection pressure was investigated in this paper. Experimental results showed that are quite different from the disappearance of it and it is harder to disappear. Biodiesel and longer nozzle orifices were hard for the hydraulic flip phenomenon to occur, and the disappearance of hydraulic flip phenomenon has great influence on the spray cone angle and the discharge coefficient.
Numerical Simulation of the Centrifugal Separator for Oil-Water Emulsion
Authors: Kharkov Nikita , Ermak Olga , Aver’yanova Olesya
Published: June 2014

Calculation of a centrifugal water oil separator is shown. The separator represents alternative method of purifying water of oil inclusions and sludge (at a concentration up to 12%). The problems of creating a computational mesh, defining boundary conditions, separation two phases of oil-water emulsion and efficiency of separation are considered.
Numerical Simulation on Internal Flows of Reducing Cross
Authors: Yuan Jian Ping , Sun Wen Ting , Luo Yin , Zhou Bang Lun
Published: June 2014

In order to study the internal flows and hydraulic loss of reducing cross, numerical simulation was carried out on a horizontally installed reducing cross. Three schemes of pipe diameters were studied. The time-averaged N-S equations of three-dimensional steady flows in the reducing pipe were calculated by CFX 14.5 based on the standard - two equation turbulence model together with standard wall function. The results show that the higher the inlet velocity, the hydraulic loss become larger when the split ratios are same for the reducing cross. With the uniform inlet velocities the higher the inlet velocity, the quicker the increasing rate of the hydraulic loss in main pipe, as well as the branch pipe. The integral change rules of hydraulic loss are similar with the condition of uniform flow rate inflow when the flow patterns at inlet are uniform. But with the same spilt ratio, the hydraulic loss of uniform velocity inflow is markedly less than that of uniform flow rate inflow in both main pipe and branch pipe. The bigger the differences of the diameters between the main pipe and the branch pipe, the larger the hydraulic loss of the branch pipe.
The deaf cannot see: An accumulation of blindness and deafness as combined theme in Isaiah 42 and 43
Authors: Van der Walt Chris
Published: June 2014

In the Bible the words blind and deaf occur nine times in the same sentence. An accumulation of such sentences is found in Isaiah 42 and 43, where it occurs three times (Is 42:18, 19; 43:8). Blindness is also mentioned in two further sentences in these chapters. Not only is it stated that the people of God is blind, but Israel also accuses Yahweh that their way is hidden from him (Is 40:27). It is because of this accusation, pertaining to an alleged blindness on Yahweh’s side, that the question of hearing is raised. He answers to this accusation in the heavenly court with the questions ‘Do you not know? Have you not heard?’ From there on God makes it clear that seeing is dependent on hearing. In a heavenly court of law, the wrong perception that God’s people had about the exile was put straight and a new beginning for the exiles was subsequently made. The theme of blind- and deafness is thereby continued from Isaiah 1 and 6 in the verdict in the heavenly court in Isaiah 43, where it became clear that the cure for the spiritual blindness of God’s people is not related to their eyes, but to their ears.In die Bybel kom die woorde blind en doof nege keer saam in dieselfde sin voor. ’n Opeenhoping van hierdie sinne word in Jesaja 42 en 43 aangetref waar dit drie maal voorkom (Jes 42:18, 19; 43:8). Blindheid word ook in twee verdere sinne in hierdie hoofstukke genoem. Nie alleen word dit gestel dat die volk van God blind is nie, maar die volk beskuldig God dat Hy nie raaksien wat van hulle word nie (Jes 40:27). In die hemelse hof antwoord God op hierdie beskuldiging met die vrae ‘Weet julle nie? Het julle nie gehoor nie?’ Van daardie punt af maak God dit duidelik dat sien van hoor afhanklik is. Hierdie verkeerde persepsie van die volk oor God se sogenaamde blindheid vir hulle welstand tydens die ballingskap, word reggestel en ’n nuwe begin word gemaak. Die tema van blind- en doofheid word sodoende uit Jesaja 1 en 6 voortgesit in die uitspraak wat in die hemelse hof gemaak word (Jes 43). Daar word dit duidelik dat die oplossing vir die geestelike blindheid van die volk nie verband hou met hulle sig nie, maar met hulle gehoor.
African Primary Care Research: Quantitative analysis and presentation of results
Authors: Mash Bob , Ogunbanjo Gboyega A.
Published: June 2014

This article is part of a series on Primary Care Research Methods. The article describes types of continuous and categorical data, how to capture data in a spreadsheet, how to use descriptive and inferential statistics and, finally, gives advice on how to present the results in text, figures and tables. The article intends to help Master’s level students with writing the data analysis section of their research proposal and presenting their results in their final research report.
An assessment of the performance of the Monitor for AeRosols and GAses in ambient air (MARGA): a semi-continuous method for soluble compounds
Authors: Rumsey I. C. , Cowen K. A. , Walker J. T. , Kelly T. J. , Hanft E. A. , Mishoe K. , Rogers C. , Proost R. , Beachley G. M. , Lear G. , Frelink T. , Otjes R. P.
Published: June 2014

Abstract. Ambient air monitoring as part of the US Environmental Protection Agency's (US EPA's) Clean Air Status and Trends Network (CASTNet) currently uses filter packs to measure weekly integrated concentrations. The US EPA is interested in supplementing CASTNet with semi-continuous monitoring systems at select sites to characterize atmospheric chemistry and deposition of nitrogen and sulfur compounds at higher time resolution than the filter pack. The Monitor for AeRosols and GAses in ambient air (MARGA) measures water-soluble gases and aerosols at an hourly temporal resolution. The performance of the MARGA was assessed under the US EPA Environmental Technology Verification (ETV) program. The assessment was conducted in Research Triangle Park, North Carolina, from 8 September to 8 October 2010 and focused on gaseous SO2, HNO3, and NH3 and aerosol SO42-, NO3-, and NH4+. Precision of the MARGA was evaluated by calculating the median absolute relative percent difference (MARPD) between paired hourly results from duplicate MARGA units (MUs), with a performance goal of ≤ 25%. The accuracy of the MARGA was evaluated by calculating the MARPD for each MU relative to the average of the duplicate denuder/filter pack concentrations, with a performance goal of ≤ 40%. Accuracy was also evaluated by using linear regression, where MU concentrations were plotted against the average of the duplicate denuder/filter pack concentrations. From this, a linear least squares line of best fit was applied. The goal was for the slope of the line of best fit to be between 0.8 and 1.2. The MARGA performed well in comparison to the denuder/filter pack for SO2, SO42−, and NH4+, with all three compounds passing the accuracy and precision goals by a significant margin. The performance of the MARGA in measuring NO3- could not be evaluated due to the different sampling efficiency of coarse NO3- by the MUs and the filter pack. Estimates of "fine" NO3- were calculated for the MUs and the filter pack. Using this and results from a previous study, it is concluded that if the MUs and the filter pack were sampling the same particle size, the MUs would have good agreement in terms of precision and accuracy. The MARGA performed moderately well in measuring HNO3 and NH3, though neither met the linear regression slope goals. However, recommendations for improving the measurement of HNO3 and NH3 are discussed. It is concluded that SO42-, SO2, NO3-, HNO3, NH4+, and NH3 concentrations can be measured with acceptable accuracy and precision when the MARGA is operated in conjunction with the recommendations outlined in the manuscript.
Surface-sensible and latent heat fluxes over the Tibetan Plateau from ground measurements, reanalysis, and satellite data
Authors: Shi Q. , Liang S.
Published: June 2014

Abstract. Estimations from meteorological stations over the Tibetan Plateau (TP) indicate that since the 1980s the surface-sensible heat flux has been decreasing continuously, and modeling studies suggest that such changes are likely linked to the weakening of the East Asian Monsoon through exciting Rossby wave trains. However, the spatial and temporal variations in the surface-sensible and latent heat fluxes over the entire TP remain unknown. This study aims to characterize the spatial and seasonal variability of the surface-sensible and latent heat fluxes at 0.5° over the TP from 1984 to 2007 by synthesizing multiple data sources including ground measurements, reanalysis products, and remote-sensing products. The root mean square errors (RMSEs) from cross validation are 14.3 Wm−2 and 10.3 Wm−2 for the monthly fused sensible and latent heat fluxes, respectively. The fused sensible and latent heat-flux anomalies are consistent with those estimated from meteorological stations, and the uncertainties of the fused data are also discussed. The associations among the fused sensible and latent heat fluxes and the related surface anomalies such as mean temperature, temperature range, snow cover, and normalized difference vegetation index (NDVI) in addition to atmospheric anomalies such as cloud cover and water vapor show seasonal dependence, suggest that the land–biosphere–atmosphere interactions over the TP could display nonuniform feedbacks to the climate changes. It would be interesting to disentangle the drivers and responses of the surface-sensible and latent heat-flux anomalies over the TP in future research from evidences of modeling results.
Measurements of OH and RO2 radicals at Dome C, East Antarctica
Authors: Kukui A. , Legrand M. , Preunkert S. , Frey M. M. , Loisil R. , Gil Roca J. , Jourdain B. , King M. D. , France J. L. , Ancellet G.
Published: June 2014

Abstract. Concentrations of OH radicals and the sum of peroxy radicals, RO2, were measured in the boundary layer for the first time on the East Antarctic Plateau at the Concordia Station (Dome C, 75.10° S, 123.31° E) during the austral summer 2011/2012. The median concentrations of OH and RO2 radicals were 3.1 × 106 molecule cm−3 and 9.9 × 107 molecule cm−3, respectively. These values are comparable to those observed at the South Pole, confirming that the elevated oxidative capacity of the Antarctic atmospheric boundary layer found at the South Pole is not restricted to the South Pole but common over the high Antarctic plateau. At Concordia, the concentration of radicals showed distinct diurnal profiles with the median maximum of 5.2 × 106 molecule cm−3 at 11:00 and the median minimum of 1.1 × 106 molecule cm−3 at 01:00 for OH radicals and 1.7 × 108 molecule cm−3 and 2.5 × 107 molecule cm−3 for RO2 radicals at 13:00 and 23:00, respectively (all times are local times). Concurrent measurements of O3, HONO, NO, NO2, HCHO and H2O2 demonstrated that the major primary source of OH and RO2 radicals at Dome C was the photolysis of HONO, HCHO and H2O2, with the photolysis of HONO contributing ∼75% of total primary radical production. However, photochemical modelling with accounting for all these radical sources overestimates the concentrations of OH and RO2 radicals by a factor of 2 compared to field observations. Neglecting the OH production from HONO in the photochemical modelling results in an underestimation of the concentrations of OH and RO2 radicals by a factor of 2. To explain the observations of radicals in this case an additional source of OH equivalent to about 25% of measured photolysis of HONO is required. Even with a factor of 4 reduction in the concentrations of HONO, the photolysis of HONO represents the major primary radical source at Dome C. Another major factor leading to the large concentration of OH radicals measured at Dome C was large concentrations of NO molecules and fast recycling of peroxy radicals to OH radicals.
The Interreg IV Italia-Austria "SeismoSAT" project: connecting seismic data centers via satellite
Authors: Pesaresi D. , Lenhardt W. , Rauch M. , Živčić M. , Steiner R. , Fabris P. , Bertoni M.
Published: June 2014

Abstract. Since 2002 OGS (Istituto Nazionale di Oceanografia e di Geofisica Sperimentale) in Udine (Italy), the Zentralanstalt für Meteorologie und Geodynamik (ZAMG) in Vienna (Austria), and the Agencija Republike Slovenije za Okolje (ARSO) in Ljubljana (Slovenia) are using the Antelope software suite as the main tool for collecting, analyzing, archiving and exchanging seismic data in real time, initially in the framework of the EU Interreg IIIA project "Trans-national seismological networks in the South-Eastern Alps" (Bragato et al., 2004, 2010). The data exchange has proved to be effective and very useful in case of seismic events near the borders between Italy, Austria and Slovenia, where the poor single national seismic networks coverage precluded a correct localization, while the usage of common data from the integrated networks improves considerably the overall reliability of real time seismic monitoring of the area (Fig. 1). At the moment the data exchange between the seismic data centers relies on their internet connections: this however is not an ideal condition for civil protection purposes, since the reliability of standard internet connections is poor. For this reason in 2012 the Protezione Civile della Provincia Autonoma di Bolzano in Bolzano (PCBZ, Italy), OGS, ZAMG subsidiary in Tirol (ZAMG Tirol) and ARSO joined in the Interreg IV Italia-Austria Project "SeismoSAT" (Progetto SeismoSAT, 2012) aimed in connecting the seismic data centers in real time via satellite. ARSO does not belong to the Interreg Italia-Austria region: for this reason ARSO joined the SeismoSAT project as an "associated partner", which, according to Interreg rules can not be funded. ARSO participation in the project is therefore at the beginning limited in benefiting only indirectly from improvement in the robustness of the data exchange between the other data centers, while eventually fully taking part in the project if other sources of funding will be available. The project is in a preliminary phase: the general schema of the project, including first data bandwidth estimates and a possible architecture are here illustrated.
The large-scale spatio-temporal variability of precipitation over Sweden observed from the weather radar network
Authors: Devasthale A. , Norin L.
Published: June 2014

Abstract. Using measurements from the national network of 12 weather radar stations for the 11-year period 2000–2010, we investigate the large-scale spatio-temporal variability of precipitation over Sweden. These statistics provide useful information to evaluate regional climate models as well as for hydrology and energy applications. A strict quality control is applied to filter out noise and artifacts from the radar data. We focus on investigating four distinct aspects: the diurnal cycle of precipitation and its seasonality, the dominant timescale (diurnal versus seasonal) of variability, precipitation response to different wind directions, and the correlation of precipitation events with the North Atlantic Oscillation (NAO) and the Arctic Oscillation (AO). When classified based on their intensity, moderate- to high-intensity events (precipitation > 0.34 mm/3 h) peak distinctly during late afternoon over the majority of radar stations in summer and during late night or early morning in winter. Precipitation variability is highest over the southwestern parts of Sweden. It is shown that the high-intensity events (precipitation > 1.7 mm/3 h) are positively correlated with NAO and AO (esp. over northern Sweden), while the low intensity events are negatively correlated (esp. over southeastern parts). It is further observed that southeasterly winds often lead to intense precipitation events over central and northern Sweden, while southwesterly winds contribute most to the total accumulated precipitation for all radar stations. Apart from its operational applications, the present study demonstrates the potential of the weather radar data set for studying climatic features of precipitation over Sweden.
An integrated approach toward the incorporation of clouds in the temperature retrievals from microwave measurements
Authors: Navas-Guzmán F. , Stähli O. , Kämpfer N.
Published: June 2014

Abstract. In this paper, we address the characterization of clouds and its inclusion in microwave retrievals in order to study its effect on tropospheric temperature profiles measured by TEMPERA radiometer. TEMPERA is the first ground-based microwave radiometer that makes it possible to obtain temperature profiles in the troposphere and stratosphere at the same time. In order to characterize the clouds a multi-instrumental approach has been adopted. Cloud base altitudes were detected using ceilometer measurements while the integrated liquid water was measured by TROWARA radiometer. Both instruments are co-located with TEMPERA in Bern (Switzerland). Using this information and a constant Liquid Water Content value inside the cloud a liquid profile is provided to characterize the clouds in the inversion algorithm. Microwave temperature profiles have been obtained incorporating this water liquid profile in the inversion algorithm and also without considering the clouds, in order to assess its effect on the retrievals. The results have been compared with the temperature profiles from radiosondes which are launched twice a day at the aerological station of MeteoSwiss in Payerne (40 km W of Bern). Almost 1 year of data have been analysed and 60 non-precipitating cloud cases were studied. The statistical analysis carried out over all the cases evidenced that temperature retrievals improved in most of the cases when clouds were incorporated in the inversion algorithm.
Cloud mask via cumulative discriminant analysis applied to satellite infrared observations: scientific basis and initial evaluation
Authors: Amato U. , Lavanant L. , Liuzzi G. , Masiello G. , Serio C. , Stuhlmann R. , Tjemkes S. A.
Published: June 2014

Abstract. We introduce a classification method (Cumulative Discriminant Analysis) of the Discriminant Analysis type to discriminate between cloudy and clear sky satellite observations in the thermal infrared. The tool is intended for the high spectral resolution infrared sounder (IRS) planned for the geostationary METEOSAT (Meteorological Satellite) Third Generation platform and uses IASI (Infrared Atmospheric Sounding Interferometer) data as a proxy. The Cumulative Discriminant Analysis does not introduce biases intrinsic with the approximation of the probability density functions and is flexible enough to adapt to different strategies to optimize the cloud mask. The methodology is based on nine statistics computed from IASI spectral radiances, which exploit the high spectral resolution of the instrument and which effectively summarize information contained within the IASI spectrum. A Principal Component Analysis prior step is also introduced which makes the problem more consistent with the statistical assumptions of the methodology. An initial assessment of the scheme is performed based on global and regional IASI real data sets and cloud masks obtained from AVHRR (Advanced Very High Resolution Radiometer) and SEVIRI (Spinning Enhanced Visible and Infrared Imager) imagers. The agreement with these independent cloud masks is generally well above 80%, except at high latitudes in their winter seasons.
Deployment of a sequential two-photon laser induced fluorescence sensor for the detection of gaseous elemental mercury at ambient levels: fast, specific, ultrasensitive detection with parts-per-quadrillion sensitivity
Authors: Bauer D. , Everhart S. , Remeika J. , Tatum Ernest C. , Hynes A. J.
Published: June 2014

Abstract. The operation of a laser-based sensor for gas phase elemental mercury, Hg(0), is described. It utilizes sequential two photon laser excitation with detection of blue shifted laser induced fluorescence to provide a highly specific detection scheme that precludes detection of anything other than atomic mercury. It has high sensitivity, fast temporal resolution, and can be deployed for in-situ measurements in the open atmosphere with essentially no perturbation of the environment. An ambient sample can also be pulled through a fluorescence cell allowing standard addition calibrations of the concentration. No type of preconcentration is required and there appears to be no significant interferences from other atmospheric constituents including gas phase oxidized mercury species. As a consequence, is not necessary to remove RGM from the air sample. The instrument has been deployed as part of an instrument intercomparison and compares well with conventional instrumentation that utilizes preconcentration on gold followed by analysis using Cold Vapor Atomic Fluorescence Spectroscopy. Currently, the achievable detection sensitivity is ~ 15 pg m−3 (~ 5 × 104 atoms cm−3, ~ 2 ppq) at a sampling rate of 0.1Hz i.e. averaging 100 shots with a 10 Hz laser system. Preliminary results are described for a 50 Hz instrument that utilizes a modified excitation sequence and has monitored ambient elemental mercury with an effective sampling rate of 10 Hz. Additional work is required to produce the precision necessary to perform eddy correlation measurements. Addition of a pyrolysis channel should allow the measurement of Total Gaseous Mercury, and hence Reactive Gaseous Mercury (by difference) with good sensitivity and time resolution.
Multichannel analysis of correlation length of SEVIRI images around ground-based cloud observatories to determine their representativeness
Authors: Slobodda J. , Hünerbein A. , Lindstrot R. , Preusker R. , Ebell K. , Fischer J.
Published: June 2014

Abstract. Images of the geostationary Meteosat-9 SEVIRI instrument during the year 2012 are analyzed with respect to the representativeness of the observations of eight cloud observatories in Europe. Cloudy situations are selected to get a time series for every pixel in a 300 km × 300 km area centered around each ground station. Then the Pearson correlation coefficient of each time series to the one of the pixel nearest to the corresponding ground site is calculated. The area for which a station is representative is defined by the characteristic radius around each station for each SEVIRI channel, where the average correlation falls below 0.9. It is found that measurements in the visible and near infrared channels, which respond to cloud microphysics, are correlated in an area with a 1 to 4 km radius, while the thermal channels, that correspond to cloud top temperature, are correlated to a distance of about 20 km. The defined radius even increases for the water vapor and ozone channels. While all stations in Central Europe are quite alike, the correlations around the station in the mountains of southern Italy are much lower. Additionally correlations at different distances corresponding to the grid box sizes of forecast models were compared. The results show good comparability between regional forecast models (grid size ≲ 10 km) and ground-based measurements since the correlations in less than 10 km distance are in all cases higher than 0.8. For larger distances like they are typical for global models (grid size ≳ 20 km) the correlations decrease to 0.6, especially for shortwave measurements and corresponding cloud products. By comparing daily means, the characteristic radius of each station is increased to about 3 to 10 times the value of instantaneous measurements and also the comparability to models grows.
Laminated sediments in the Bering Sea reveal atmospheric teleconnections to Greenland climate on millennial to decadal timescales during the last deglaciation
Authors: Kuehn H. , Lembke-Jene L. , Gersonde R. , Esper O. , Lamy F. , Arz H. , Tiedemann R.
Published: June 2014

Abstract. During the last glacial termination, the upper North Pacific Ocean underwent dramatic and rapid changes in oxygenation that lead to the transient intensification of Oxygen Minimum Zones (OMZs), recorded by the widespread occurrence of laminated sediments on circum-Pacific continental margins. We present a new laminated sediment record from the mid-depth (1100 m) northern Bering Sea margin that provides insight into these deglacial OMZ maxima with exceptional, decadal-scale detail. Combined ultrahigh-resolution micro-XRF data and sediment facies analysis of laminae reveals an alternation between predominantly terrigenous and diatom-dominated opal sedimentation. The diatomaceous laminae are interpreted to represent spring/summer productivity events that occur at the retreating sea ice margin. We identified five laminated sections in the deglacial part of our site. Laminae counts were carried out on these sections and correlated to the Bølling–Allerød and Preboreal phases in North Greenland Ice Core (NGRIP) oxygen isotope record, indicating an annual deposition of individual laminae couplets. The observed rapid intra-decadal intensifications of anoxia, in particular within the Bølling–Allerød, are tightly coupled to short-term warm events through increases in regional biogenic productivity. By correlating the counted laminated sections with Bering Sea Surface Temperature records (SST) and NGRIP δ18O data, we propose a deglacial minimum SST of 6–7 °C for the preservation of laminae, which we call the deglacial temperature threshold for anoxia occurrence, a process that strongly implies a close atmospheric teleconnection between the North Pacific and North Atlantic regions. We suggest that concomitant increases in Bering Sea biogenic productivity, in combination with oxygen-poor waters entering the Being Sea, drove down oxygen concentrations to values below 0.1 mL L-1 and caused laminae preservation. Calculated benthic-planktic ventilation ages show no significant variations throughout the last deglaciation, indicating that changes in formation rates or differing sources of North Pacific mid-depth waters are not prime candidates for strengthening the OMZ at our site. The age models established by our correlation procedure allow to determine calendar age control points for the Bølling–Allerød and the Preboreal that are independent of the initial radiocarbon-based chronology. Resulting calculated reservoir ages are 875 yr during the Bølling–Allerød, and 910–770 yr for the Younger Dryas and the Preboreal, respectively.
Global hydrological droughts in the 21st century under a changing hydrological regime
Authors: Wanders N. , Wada Y. , Van Lanen H. A. J.
Published: June 2014

Abstract. Climate change very likely impacts future hydrological drought characteristics across the world. Here, we quantify the impact of climate change on future low flows and associated hydrological drought characteristics on a global scale using an alternative drought identification approach that considers adaptation to future changes in hydrological regime. The global hydrological model PCR-GLOBWB was used to simulate daily discharge at 0.5° globally for 1971–2099. The model was forced with CMIP5 climate projections taken from five GCMs and four emission scenarios (RCPs), from the Inter-Sectoral Impact Model Intercomparison Project. Drought events occur when discharge is below a threshold. The conventional variable threshold (VTM) was calculated by deriving the threshold from the period 1971–2000. The transient variable threshold (VTMt) is a non-stationary approach, where the threshold is based on the discharge values of the previous 30 years implying the threshold to vary every year during the 21st century. The VTMt adjusts to gradual changes in the hydrological regime as response to climate change. Results show a significant negative trend in the low flow regime over the 21st century for large parts of South America, southern Africa, Australia and the Mediterranean. In 40–52% of the world reduced low flows are projected, while increased low flows are found in the snow dominated climates. In 27% of the global area both the drought duration and the deficit volume are expected to increase when applying the VTMt. However, this area will significantly increase to 62% when the VTM is applied. The mean global area in drought, with the VTMt, remains rather constant (11.7 to 13.4%), compared to the substantial increase when the VTM is applied (11.7 to 20%). The study illustrates that an alternative drought identification that considers adaptation to an altered hydrological regime, has a substantial influence on future hydrological drought characteristics.
GO5.0: the joint NERC–Met Office NEMO global ocean model for use in coupled and forced applications
Authors: Megann A. , Storkey D. , Aksenov Y. , Alderson S. , Calvert D. , Graham T. , Hyder P. , Siddorn J. , Sinha B.
Published: June 2014

Abstract. We describe a new Global Ocean standard configuration (GO5.0) at eddy-permitting resolution, developed jointly between the National Oceanography Centre and the Met Office as part of the Joint Ocean Modelling Programme (JOMP), a working group of the UK's National Centre for Ocean Forecasting (NCOF) and part of the Joint Weather and Climate Research Programme (JWCRP). The configuration has been developed with the seamless approach to modelling in mind for ocean modelling across timescales and for a range of applications, from short-range ocean forecasting through seasonal forecasting to climate predictions as well as research use. The configuration has been coupled with sea ice (GSI5.0), atmosphere (GA5.0), and land-surface (GL5.0) configurations to form a standard coupled global model (GC1). The GO5.0 model will become the basis for the ocean model component of the Forecasting Ocean Assimilation Model, which provides forced short-range forecasting services. The GC1 or future releases of it will be used in coupled short-range ocean forecasting, seasonal forecasting, decadal prediction and for climate prediction as part of the UK Earth System Model. A 30-year integration of GO5.0, run with CORE2 (Common Ocean-ice Reference Experiments) surface forcing from 1976 to 2005, is described, and the performance of the model in the final 10 years of the integration is evaluated against observations and against a comparable integration of an existing standard configuration, GO1. An additional set of 10-year sensitivity studies, carried out to attribute changes in the model performance to individual changes in the model physics, is also analysed. GO5.0 is found to have substantially reduced subsurface drift above the depth of the thermocline relative to GO1, and also shows a significant improvement in the representation of the annual cycle of surface temperature and mixed layer depth.
Testing conceptual and physically based soil hydrology schemes against observations for the Amazon Basin
Authors: Guimberteau M. , Ducharne A. , Ciais P. , Boisier J. P. , Peng S. , De Weirdt M. , Verbeeck H.
Published: June 2014

Abstract. This study analyzes the performance of the two soil hydrology schemes of the land surface model ORCHIDEE in estimating Amazonian hydrology and phenology for five major sub-basins (Xingu, Tapajós, Madeira, Solimões and Negro), during the 29-year period 1980–2008. A simple 2-layer scheme with a bucket topped by an evaporative layer is compared to an 11-layer diffusion scheme. The soil schemes are coupled with a river routing module and a process model of plant physiology, phenology and carbon dynamics. The simulated water budget and vegetation functioning components are compared with several data sets at sub-basin scale. The use of the 11-layer soil diffusion scheme does not significantly change the Amazonian water budget simulation when compared to the 2-layer soil scheme (+3.1 and −3.0% in evapotranspiration and river discharge, respectively). However, the higher water-holding capacity of the soil and the physically based representation of runoff and drainage in the 11-layer soil diffusion scheme result in more dynamic soil water storage variation and improved simulation of the total terrestrial water storage when compared to GRACE satellite estimates. The greater soil water storage within the 11-layer scheme also results in increased dry-season evapotranspiration (+0.5 mm d−1, +17%) and improves river discharge simulation in the southeastern sub-basins such as the Xingu. Evapotranspiration over this sub-basin is sustained during the whole dry season with the 11-layer soil diffusion scheme, whereas the 2-layer scheme limits it after only 2 dry months. Lower plant drought stress simulated by the 11-layer soil diffusion scheme leads to better simulation of the seasonal cycle of photosynthesis (GPP) when compared to a GPP data-driven model based on eddy covariance and satellite greenness measurements. A dry-season length between 4 and 7 months over the entire Amazon Basin is found to be critical in distinguishing differences in hydrological feedbacks between the soil and the vegetation cover simulated by the two soil schemes. On average, the multilayer soil diffusion scheme provides little improvement in simulated hydrology over the wet tropical Amazonian sub-basins, but a more significant improvement is found over the drier sub-basins. The use of a multilayer soil diffusion scheme might become critical for assessments of future hydrological changes, especially in southern regions of the Amazon Basin where longer dry seasons and more severe droughts are expected in the next century.