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1

The change in wind vector and dust storm in the Middle East in last 32 years and their correlations  

NASA Astrophysics Data System (ADS)

[1] Winds play an important role in dust aerosols emission, transport, and deposition. Using NCEP reanalysis2 data, the changes in wind direction and speed during 1948 and 2010 were analyzed over the Middle East (the Gulf of Omen and Eastern Saudi Arabia abbreviated as R1). Wind patterns from R1 were compared with those in South Asia Monsoon Area (R2), East China (R3), and East China Sea (R4). The Weather Research and Forecasting model with online chemistry (WRF-Chem) was used to study the effects of winds change on dust emissions over the period from 1979 to 2010. Modifications to soil types and land cover types were implemented to the default WRF-Chem MOSAIC dust scheme to ensure realistic simulations of dust emissions. In all the four regions, the yearly average wind speed decreased. In R1 and R3, winds greater than 2.5 m/s exhibited a decreasing trend throughout the year; while in R2 and R4, the decreasing trend was found only in spring and summer. The model simulations were compared with available observations including satellite data (e.g. AERONET and Calipso) and continual improvements are being made to revise the dust emission scheme within WRF-Chem.

Jin, Q.; Yang, Z.

2011-12-01

2

Support vector machines for wind speed prediction  

Microsoft Academic Search

This paper introduces support vector machines (SVM), the latest neural network algorithm, to wind speed prediction and compares their performance with the multilayer perceptron (MLP) neural networks. Mean daily wind speed data from Madina city, Saudi Arabia, is used for building and testing both models. Results indicate that SVM compare favorably with the MLP model based on the root mean

M. A. Mohandes; T. O. Halawani; S. Rehman; Ahmed A. Hussain

2004-01-01

3

Wind Vectors for Hurricane Erin (WMS)  

NSDL National Science Digital Library

This visualization shows wind vectors for Hurricane Erin on September 10, 2001. Wind direction and speed are represented by the direction and speed of moving arrows, respectively. This animation represents a single measurement taken by the SeaWinds instrument on the QuikSCAT satellite, taken at 14:27:00 UTC on September 10, 2001. The WMS version of this animation which is available through the SVS Image Server (http:--aes.gsfc.nasa.gov) presents this animation with a different timestamp for each frame in order to more easily present the images as an animation. It should be noted that each frame really has a time stamp of 2001-09-10 14:27:00 UTC.

Sokolowsky, Eric; Shirah, Greg; Halverson, Jeff

2004-02-11

4

Directional attributes of the ocean surface wind stress vector  

Microsoft Academic Search

In a recent paper by Geernaert (1988) it was suggested that the stress and wind vectors are rarely aligned and that the deviation of the stress vector direction from the wind vector is related to the surface heat flux. It was argued that since cold air advection over the open ocean generally corresponds to upward heat flux, the consequent rotation

G. L. Geernaert; Finn Hansen; Micheal Courtney; Tom Herbers

1993-01-01

5

Evaluation of wind vectors observed by QuikSCAT\\/SeaWinds using ocean buoy data  

Microsoft Academic Search

Wind vectors observed by QuikSCAT\\/SeaWinds are compared with wind and wave data from offshore moored buoys. Effects of oceanographic and atmospheric parameters on the scatterometry are also assessed by using the buoy data. The QuikSCAT\\/SeaWinds Standard Wind Data Products (Level 2B) were collocated with the Japan Meteorological Agency (JMA), National Data Buoy Center (NDBC), and Tropical Atmosphere Ocean (TAO) buoys.

Naoto Ebuchi

2001-01-01

6

The MISR Cloud Motion Vector Product: 10 years of height resolved, cloud-track winds  

NASA Astrophysics Data System (ADS)

By utilizing multiple camera views and fast image matching algorithms to identify common features and determine feature motion, the MISR instrument on NASA’s Terra satellite has now collected 10 years of height-resolved, cloud-track, vector winds using a single, globally consistent algorithm. MISR cloud-track winds are packaged within the new MISR Cloud Motion Vector product, reported on mesoscale domains of 70.4 km × 70.4 km and referenced to stereoscopically derived heights above the earth ellipsoid with a nominal precision of 230 m. Importantly, from the standpoint of climate research, the stereo height assignment and wind retrieval are largely insensitive to instrument calibration changes and independent of a priori assumptions because the product algorithms depend only on patterns of observed brightness variability. We will describe comparisons with other wind observations, including geostationary cloud drift winds, raob winds, and scatterometer surface winds that demonstrate the quality of the MISR winds. We will also show the coverage and resolution advantages that MISR provides relative to these other datasets. Additionally, we will analyze agreement and discrepancies between MISR winds and reanalysis winds.

Mueller, K.; Garay, M. J.; Jovanovic, V.; Moroney, C.; Wu, D. L.; Diner, D. J.

2010-12-01

7

Vector Wind Estimation From GPS Sea Reflections  

Microsoft Academic Search

Recently, there has been considerable interest in the possibility of estimating various parameters of geophysical interest by measuring the signals from the Global Positioning Satellite (GPS) constellation reflected from the ocean surface. Since the original suggestion by Martín-Neira [1993], it has been further argued [Garrison et al., 1998] that information on the local wind field may be contained in the

D. R. Thompson; T. M. Elfouhaily; R. F. Gasparovic; L. A. Linstrom

2001-01-01

8

Seasonal rotation features of wind vectors and application to evaluate monsoon simulations in AMIP models  

Microsoft Academic Search

A new concept, the directed angle, is introduced to study seasonal rotation regimes of global wind vectors and annual variability\\u000a of monsoon. Compared with previous studies on using angles between wind vectors, this concept better describes the daily variations\\u000a of both rotation direction and rotation amplitude of wind vector. According to the concept, six categories of wind vector\\u000a rotation with

Li Zhang; Jianping Li

2008-01-01

9

10 Years of Height Resolved, Cloud-Track, Vector Winds from MISR  

NASA Astrophysics Data System (ADS)

By utilizing multiple camera views and fast image matching algorithms to identify common features and determine feature motion, the MISR instrument on NASA’s Terra satellite has now collected nearly 10 years of height-resolved, cloud-track, vector winds using a single, globally consistent algorithm. The MISR cloud-track winds are reported globally on mesoscale domains of 70.4 km × 70.4 km and referenced to stereoscopically derived heights above the earth ellipsoid, which have a nominal vertical resolution of approximately 500 m. Importantly, from the standpoint of climate research, the stereo height assignment and wind retrieval are largely insensitive to instrument calibration changes because the pattern matcher relies only on relative brightness values, rather than the absolute magnitude of the brightness. We will describe comparisons with other wind datasets, including geostationary cloud drift winds, scatterometer surface winds, and reanalysis model winds, that demonstrate the quality of the MISR winds. We will also show the coverage and resolution advantages that MISR provides relative to these other datasets. Additionally, because the global winds are driven primarily by the global (im)balance of heating, monitoring variations in the winds over 10 years promises to yield important insights into the processes related to the hydrologic cycle and transport of heat and water vapor, such as the Madden-Julian Oscillation (MJO) and the El Niño Southern Oscillation (ENSO).

Garay, M. J.; Mueller, K. J.; Moroney, C. M.; Jovanovic, V.; Wu, D. L.; Diner, D. J.

2009-12-01

10

Comparison of ocean surface vector winds observed by SeaWinds on ADEOS-II with ocean buoy data  

Microsoft Academic Search

Wind vectors observed by SeaWinds on ADEOS-II are compared with wind and wave data from offshore moored buoys. The wind data were collocated with buoy observations operated by the National Data Buoy Center (NDBC), Tropical Atmosphere Ocean (TAO), and Pilot Research Moored Array in the Tropical Atlantic (PIRATA) projects. Only buoys located offshore and in deep water were selected. Temporal

Naoto Ebuchi; Hans C. Graber; Michael J. Caruso

2004-01-01

11

Triboelectric nanogenerator for harvesting wind energy and as self-powered wind vector sensor system.  

PubMed

We report a triboelectric nanogenerator (TENG) that plays dual roles as a sustainable power source by harvesting wind energy and as a self-powered wind vector sensor system for wind speed and direction detection. By utilizing the wind-induced resonance vibration of a fluorinated ethylene-propylene film between two aluminum foils, the integrated TENGs with dimensions of 2.5 cm × 2.5 cm × 22 cm deliver an output voltage up to 100 V, an output current of 1.6 ?A, and a corresponding output power of 0.16 mW under an external load of 100 M?, which can be used to directly light up tens of commercial light-emitting diodes. Furthermore, a self-powered wind vector sensor system has been developed based on the rationally designed TENGs, which is capable of detecting the wind direction and speed with a sensitivity of 0.09 ?A/(m/s). This work greatly expands the applicability of TENGs as power sources for self-sustained electronics and also self-powered sensor systems for ambient wind detection. PMID:24044652

Yang, Ya; Zhu, Guang; Zhang, Hulin; Chen, Jun; Zhong, Xiandai; Lin, Zong-Hong; Su, Yuanjie; Bai, Peng; Wen, Xiaonan; Wang, Zhong Lin

2013-09-17

12

Evaluation of Wind Vectors Measured by a Bistatic Doppler Radar Network  

Microsoft Academic Search

By installing and linking additional receivers to a monostatic Doppler radar, several wind components can be measured and combined into a wind vector field. Such a bistatic Doppler radar network was developed in 1993 by the National Center for Atmospheric Research and has been in operation at different research departments. Since then, the accuracy of wind vectors has been investigated

Katja Friedrich; Martin Hagen

2004-01-01

13

An Ocean Surface Wind Vector Model Function for a Spaceborne Microwave Radiometer  

Microsoft Academic Search

Surface wind vector measurements over the oceans are vital for scientists and forecasters to understand the Earth's global weather and climate. In the last two decades, operational measurements of global ocean wind speeds were obtained from passive microwave radiometers (Special Sensor Microwave\\/ Imagers); and over this period, full ocean surface wind vector data were obtained from several National Aeronautics and

S.. Soisuvarn; Z.. Jelenak; W. L. Jones

2007-01-01

14

Relating the Proca Photon Mass and Cosmic Vector Potential via Solar Wind  

SciTech Connect

The effect of the Proca photon mass m{sub ph} and cosmic vector potential A{sub C} on the dynamics of solar wind is considered. For large-enough values of the parameter A{sub C}m{sub ph}{sup 2}, the solar wind structure at a distance of approx40 AU from the Sun should change significantly with respect to the actual observed flow. The absence of such deviations gives an upper bound on the parameter A{sub C}m{sub ph}{sup 2} 9 orders of magnitude less than in laboratory experiments measuring torque on a toroidal magnet.

Ryutov, D. D. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

2009-11-13

15

Wind velocities on venus: vector determination by radio interferometry.  

PubMed

To determine the wind directions and speeds on Venus, as each Pioneer probe fell to the surface we tracked its motion in three dimensions using a combination of Doppler and long-baseline radio interferometric methods. Preliminary results from this tracking, coupled with results from test observations of other spacecraft, enable us to estimate the uncertainties of our eventual determinations of the velocity vectors of the probes with respect to Venus. For altitudes below about 65 kilometers and with time-averaging over 100-second intervals, all three components of the velocity should have errors of the order of 0.3 meter per second or less. PMID:17833005

Counselman, C C; Gourevitch, S A; King, R W; Pettengill, G H; Prinn, R G; Shapiro, I I; Miller, R B; Smith, J R; Ramos, R; Liebrecht, P

1979-02-23

16

Scatterometer wind vector products for application in meteorology and oceanography  

NASA Astrophysics Data System (ADS)

Scatterometers measure the radar backscatter from wind-generated cm-size gravity-capillary waves and provide high-resolution vector wind fields over the oceans. All-weather scatterometer observations have proven accurate and important for the forecasting of dynamical and severe weather. Oceanographic applications have been initiated since scatterometers provide unique forcing information on the ocean eddy scale. With the launch of the Advanced Scatterometer (ASCAT) on board MetOp-A in 2006, and the foreseen launch of its successors MetOp-B and MetOp-C in 2012 and 2017, respectively, scatterometer measurements are expected to continue until 2022 at least. In this paper the principles of scatterometer wind measurement are reviewed. The quality of scatterometer winds in terms of resolution and accuracy is assessed using statistical methods. Future product improvements are indicated. It is expected that in this decennium the number of operational scatterometers will increase substantially, leading to improved temporal sampling. This opens the way for new data products that will be useful for applications in meteorology and oceanography.

Vogelzang, Jur; Stoffelen, Ad

2012-11-01

17

Measuring the 3-D wind vector with a weight-shift microlight aircraft  

NASA Astrophysics Data System (ADS)

This study investigates whether the 3-D wind vector can be measured reliably from a highly transportable and low-cost weight-shift microlight aircraft. Therefore we draw up a transferable procedure to accommodate flow distortion originating from the aircraft body and -wing. This procedure consists of the analysis of aircraft dynamics and seven successive calibration steps. For our aircraft the horizontal wind components receive their greatest single amendment (14%, relative to the initial uncertainty) from the correction of flow distortion magnitude in the dynamic pressure computation. Conversely the vertical wind component is most of all improved (31%) by subsequent steps considering the 3-D flow distortion distribution in the flow angle computations. Therein the influences of the aircraft's aeroelastic wing (53%), as well as sudden changes in wing loading (16%) are considered by using the measured lift coefficient as explanatory variable. Three independent lines of analysis are used to evaluate the quality of the wind measurement: (a) A wind tunnel study in combination with the propagation of sensor uncertainties defines the systems input uncertainty to ?0.6 m s-1 at the extremes of a 95% confidence interval. (b) During severe vertical flight manoeuvres the deviation range of the vertical wind component does not exceed 0.3 m s-1. (c) The comparison with ground based wind measurements yields an overall operational uncertainty (root mean square deviation) of ?0.4 m s-1 for the horizontal and ?0.3 m s-1 for the vertical wind components. No conclusive dependence of the uncertainty on the wind magnitude (<8 m s-1) or true airspeed (ranging from 23-30 m s-1) is found. Hence our analysis provides the necessary basis to study the wind measurement precision and spectral quality, which is prerequisite for reliable eddy-covariance flux measurements.

Metzger, S.; Junkermann, W.; Butterbach-Bahl, K.; Schmid, H. P.; Foken, T.

2011-02-01

18

Fault diagnosis of direct-drive wind turbine based on support vector machine  

NASA Astrophysics Data System (ADS)

A fault diagnosis method of direct-drive wind turbine based on support vector machine (SVM) and feature selection is presented. The time-domain feature parameters of main shaft vibration signal in the horizontal and vertical directions are considered in the method. Firstly, in laboratory scale five experiments of direct-drive wind turbine with normal condition, wind wheel mass imbalance fault, wind wheel aerodynamic imbalance fault, yaw fault and blade airfoil change fault are carried out. The features of five experiments are analyzed. Secondly, the sensitive time-domain feature parameters in the horizontal and vertical directions of vibration signal in the five conditions are selected and used as feature samples. By training, the mapping relation between feature parameters and fault types are established in SVM model. Finally, the performance of the proposed method is verified through experimental data. The results show that the proposed method is effective in identifying the fault of wind turbine. It has good classification ability and robustness to diagnose the fault of direct-drive wind turbine.

An, X. L.; Jiang, D. X.; Li, S. H.; Chen, J.

2011-07-01

19

Climate change drives wind turbines  

Microsoft Academic Search

The development and prospects for wind power resources, technologies, investment, financing and banking, incentive policies, and operation and maintenance have become popular issues in wind power industry. An exhibition in May 2007 in Milan, Italy (EWEC 2007), with 229 stands on wind power technologies and techniques coinciding with the Conference, confirmed the popularity of these issues. Governments, International organisations, NGOs,

Ming Yang

2007-01-01

20

Use of support vector machine for wind speed prediction  

Microsoft Academic Search

The penetration of wind energy has been encouraged significantly throughout the world. The wind power is a clean, inexhaustible, and almost a free source of energy. But the integration of wind parks with the power grid has resulted in many challenges for the unity in terms of commitment and control of power plants. As wind speed and wind direction fluctuate

Patil SangitaB; Surekha. R. Deshmukh

2011-01-01

21

Short-Term Wind Energy Forecasting Using Support Vector Regression  

Microsoft Academic Search

\\u000a Wind energy prediction has an important part to play in a smart energy grid for load balancing and capacity planning. In this\\u000a paper we explore, if wind measurements based on the existing infrastructure of windmills in neighbored wind parks can be learned\\u000a with a soft computing approach for wind energy prediction in the ten-minute to six-hour range. For this sake

Oliver Kramer; Fabian Gieseke

22

Wind vector retrieval using ERS-1 synthetic aperture radar imagery  

Microsoft Academic Search

An automated algorithm intended for operational use is developed and tested for estimating wind speed and direction using ERS-1 SAR imagery. The wind direction comes from the orientation of low frequency, linear signatures in the SAR imagery that the authors believe are manifestations of roll vortices within the planetary boundary layer. The wind direction thus has inherently a 180° ambiguity

Christopher C. Wackerman; Clifford L. Rufenach; Robert A. Shuchman; Johnny A. Johannessen; Kenneth L. Davidson

1996-01-01

23

QuikSCAT Radiometer (QRad) rain rates for wind vector quality control  

Microsoft Academic Search

The Sea Winds scatterometer onboard the QuikSCAT satellite measures the ocean normalized radar cross section to infer the surface wind vector. In addition, SeaWinds simultaneously measures the polarized microwave brightness temperature of the ocean\\/atmosphere, and this passive microwave measurement capability is known as the QuikSCAT Radiometer (QRad). QRad brightness temperatures are used to infer instantaneous rain rates over oceans using

K. A. Ahmad; W. Linwood Jones; T. Kasparis

2005-01-01

24

Climate change impacts on wind energy: A review  

Microsoft Academic Search

Expansion of wind energy installed capacity is poised to play a key role in climate change mitigation. However, wind energy is also susceptible to global climate change. Some changes associated with climate evolution will likely benefit the wind energy industry while other changes may negatively impact wind energy developments, with such ‘gains and losses’ depending on the region under consideration.

S. C. Pryor; R. J. Barthelmie

2010-01-01

25

Measurement of oceanic wind vector using satellite microwave radiometers  

Microsoft Academic Search

The possibility of retrieving both wind speed and direction from microwave radiometer measurements of the ocean is studied using Special Sensor Microwave\\/Imager (SSM\\/I) measurements collocated with buoy reports from the National Data Buoy Center (NDBC). A physically based algorithm is used to retrieve the wind speed. The RMS difference between the SSM\\/I and buoy wind speed is 1.6 m\\/s for

Frank J. Wentz

1992-01-01

26

Plants and ventifacts delineate late Holocene wind vectors in the Coachella Valley, USA  

USGS Publications Warehouse

Strong westerly winds that emanate from San Gorgonio Pass, the lowest point between Palm Springs and Los Angeles, California, dominate aeolian transport in the Coachella Valley of the western Sonoran Desert. These winds deposit sand in coppice dunes that are critical habitat for several species, including the state and federally listed threatened species Uma inornata, a lizard. Although wind directions are generally defined in this valley, the wind field has complex interactions with local topography and becomes more variable with distance from the pass. Local, dominant wind directions are preserved by growth patterns of Larrea tridentata (creosote bush), a shrub characteristic of the hot North American deserts, and ventifacts. Exceptionally long-lived, Larrea has the potential to preserve wind direction over centuries to millennia, shaped by the abrasive pruning of windward branches and the persistent training of leeward branches. Wind direction preserved in Larrea individuals and clones was mapped at 192 locations. Compared with wind data from three weather stations, Larrea vectors effectively reflect annual prevailing winds. Ventifacts measured at 24 locations record winds 10° more westerly than Larrea and appear to reflect the direction of the most erosive winds. Based on detailed mapping of local wind directions as preserved in Larrea, only the northern half of the Mission-Morongo Creek floodplain is likely to supply sand to protected U. inornata habitat in the Willow Hole ecological reserve.

Griffiths, P. G.; Webb, R. H.; Fisher, M.; Muth, A.

2009-01-01

27

Mode changing stability of wind turbine in an integrated wind turbine and rechargeable battery system  

Microsoft Academic Search

Power generated by wind turbines changes due to variation in wind speed that is independent of the load power. Rechargeable batteries could be used as a reserve power source to alleviate unbalance between the load power and power generated by wind turbines. A supervisory controller is proposed for an integrated wind turbine-battery system (wind turbine electrically connected to a rechargeable

Christine A. Mecklenborg; Dushyant Palejiya; John F. Hall; Dongmei Chen

2011-01-01

28

Power smoothing in wind generation systems using a sensorless vector controlled induction Machine driving a flywheel  

Microsoft Academic Search

This paper presents a novel control strategy for power smoothing in generation systems in which power flow variations can occur. These variations are the norm in wind energy generation. The system is based on a sensorless vector controlled induction machine driving a flywheel. The induction machine is controlled to operate in a wide speed range by using flux weakening above

Roberto Cárdenas; Rubén Peña; Greg Asher; Jon Clare

2004-01-01

29

Global change and human vulnerability to vector-borne diseases.  

PubMed

Global change includes climate change and climate variability, land use, water storage and irrigation, human population growth and urbanization, trade and travel, and chemical pollution. Impacts on vector-borne diseases, including malaria, dengue fever, infections by other arboviruses, schistosomiasis, trypanosomiasis, onchocerciasis, and leishmaniasis are reviewed. While climate change is global in nature and poses unknown future risks to humans and natural ecosystems, other local changes are occurring more rapidly on a global scale and are having significant effects on vector-borne diseases. History is invaluable as a pointer to future risks, but direct extrapolation is no longer possible because the climate is changing. Researchers are therefore embracing computer simulation models and global change scenarios to explore the risks. Credible ranking of the extent to which different vector-borne diseases will be affected awaits a rigorous analysis. Adaptation to the changes is threatened by the ongoing loss of drugs and pesticides due to the selection of resistant strains of pathogens and vectors. The vulnerability of communities to the changes in impacts depends on their adaptive capacity, which requires both appropriate technology and responsive public health systems. The availability of resources in turn depends on social stability, economic wealth, and priority allocation of resources to public health. PMID:14726459

Sutherst, Robert W

2004-01-01

30

Global Change and Human Vulnerability to Vector-Borne Diseases  

PubMed Central

Global change includes climate change and climate variability, land use, water storage and irrigation, human population growth and urbanization, trade and travel, and chemical pollution. Impacts on vector-borne diseases, including malaria, dengue fever, infections by other arboviruses, schistosomiasis, trypanosomiasis, onchocerciasis, and leishmaniasis are reviewed. While climate change is global in nature and poses unknown future risks to humans and natural ecosystems, other local changes are occurring more rapidly on a global scale and are having significant effects on vector-borne diseases. History is invaluable as a pointer to future risks, but direct extrapolation is no longer possible because the climate is changing. Researchers are therefore embracing computer simulation models and global change scenarios to explore the risks. Credible ranking of the extent to which different vector-borne diseases will be affected awaits a rigorous analysis. Adaptation to the changes is threatened by the ongoing loss of drugs and pesticides due to the selection of resistant strains of pathogens and vectors. The vulnerability of communities to the changes in impacts depends on their adaptive capacity, which requires both appropriate technology and responsive public health systems. The availability of resources in turn depends on social stability, economic wealth, and priority allocation of resources to public health.

Sutherst, Robert W.

2004-01-01

31

Characterizing Tropospheric Winds by Combining MISR Cloud-Track and QuikSCAT Surface Wind Vectors  

Microsoft Academic Search

Numerous studies have found that the inclusion of wind observations results in a significantly greater improvement in operational weather forecasts compared to the addition of temperature or pressure observations alone. However, global tropospheric wind measurements are only available from 12-hourly rawinsonde launches from selected locations, primarily over land. For years the world's oceans were \\

R. Davies; M. J. Garay; C. M. Moroney; W. T. Liu

2007-01-01

32

Polarimetric passive remote sensing of wind-generated sea surfaces and ocean wind vectors  

Microsoft Academic Search

Investigates the theory of polarimetric passive remote sensing of wind-generated sea surfaces. A two-scale polarimetric scattering and emission model of sea surfaces is developed to interpret existing active and passive remote sensing microwave signatures of sea surfaces, and to investigate the potential application of polarimetric radiometry to ocean surface winds. Theoretical backscattering coefficients are compared with SASS geophysical model function,

S. H. Yueh; R. Kwok; F. K. Li; S. V. Nghiem; W. J. Wilson; J. A. Kong

1993-01-01

33

Common themes in changing vector-borne disease scenarios.  

PubMed

The impact of climate change on disease patterns is controversial. However, global burden of disease studies suggest that infectious diseases will contribute a proportionately smaller burden of disease over the next 2 decades as non-communicable diseases emerge as public health problems. However, infectious diseases contribute proportionately more in the poorest quintile of the population. Notwithstanding the different views of the impact of global warming on vector-borne infections this paper reviews the conditions which drive the changing epidemiology of these infections and suggests that such change is linked by common themes including interactions of generalist vectors and reservoir hosts at interfaces with humans, reduced biodiversity associated with anthropogenic environmental changes, increases in Plasmodium falciparum: P. vivax ratios and well-described land use changes such as hydrological, urbanization, agricultural, mining and forest-associated impacts (extractive activities, road building, deforestation and migration) which are seen on a global scale. PMID:14584362

Molyneux, David H

34

Vector control strategy for small-scale grid-connected PMSG wind turbine converter  

Microsoft Academic Search

The purpose of this paper is to find an innovative, high efficiency, practical and low cost control system structure with an optimized control strategy for small-scale grid-connected wind turbine with direct-driven permanent magnet synchronous generator (PMSG). This research adopts the sensorless vector control strategy based on phase-locked loop (PLL) for PMSG control, and the grid-side inverter control strategy is based

Chunxue Wen; Guojie Lu; Peng Wang; Zhengxi Li; Xiongwei Liu; Zaiming Fan

2011-01-01

35

Vector Winds from a Single-Transmitter Bistatic Dual-Doppler Radar Network  

Microsoft Academic Search

A bistatic dual-Doppler weather radar network consisting of only one transmitter and a nontransmitting, nonscanning, low-cost bistatic receiver was deployed in the Boulder, Colorado, area during 1993.The Boulder network took data in a variety of weather situations, including low-reflectivity stratiform snowfall, several convective cells, and a hailstorm. Dual-Doppler vector wind fields were retrieved and compared to those from a traditional,

Joshua Wurman

1994-01-01

36

3D visualization of solar wind ion data from the Chang'E-1 exploration  

NASA Astrophysics Data System (ADS)

Chang'E-1 (abbreviation CE-1), China's first Moon-orbiting spacecraft launched in 2007, carried equipment called the Solar Wind Ion Detector (abbreviation SWID), which sent back tens of gigabytes of solar wind ion differential number flux data. These data are essential for furthering our understanding of the cislunar space environment. However, to fully comprehend and analyze these data presents considerable difficulties, not only because of their huge size (57 GB), but also because of their complexity. Therefore, a new 3D visualization method is developed to give a more intuitive representation than traditional 1D and 2D visualizations, and in particular to offer a better indication of the direction of the incident ion differential number flux and the relative spatial position of CE-1 with respect to the Sun, the Earth, and the Moon. First, a coordinate system named Selenocentric Solar Ecliptic (SSE) which is more suitable for our goal is chosen, and solar wind ion differential number flux vectors in SSE are calculated from Geocentric Solar Ecliptic System (GSE) and Moon Center Coordinate (MCC) coordinates of the spacecraft, and then the ion differential number flux distribution in SSE is visualized in 3D space. This visualization method is integrated into an interactive visualization analysis software tool named vtSWIDs, developed in MATLAB, which enables researchers to browse through numerous records and manipulate the visualization results in real time. The tool also provides some useful statistical analysis functions, and can be easily expanded.

Zhang, Tian; Sun, Yankui; Tang, Zesheng

2011-10-01

37

Stator winding fault diagnosis in three-phase synchronous and asynchronous motors, by the extended Park's vector approach  

Microsoft Academic Search

This paper describes the use of the extended Park's vector approach (EPVA) for diagnosing the occurrence of stator winding faults in operating three-phase synchronous and asynchronous motors. The major theoretical principles related with the EPVA are presented and it is shown how stator winding faults can be effectively diagnosed by the use of this noninvasive approach. Experimental results, obtained in

S. M. A. Cruz; A. J. Marques Cardoso

2000-01-01

38

Stator winding fault diagnosis in three-phase synchronous and asynchronous motors, by the extended Park's vector approach  

Microsoft Academic Search

This paper describes the use of the extended Park's vector approach (EPVA) for diagnosing the occurrence of stator winding faults in operating three-phase synchronous and asynchronous motors. The major theoretical principles related with the EPVA are presented and it is shown how stator winding faults can be effectively diagnosed by the use of this noninvasive approach. Experimental results, obtained in

Sérgio M. A. Cruz; A. J. Marques Cardoso

2001-01-01

39

The probability of wind damage in forestry under a changed wind climate  

Microsoft Academic Search

We (1) estimated how the possible changes in wind climate due to climatic change may affect the probability of exceeding critical\\u000a wind speeds (CWS) expected to cause significant wind damage within a forest management unit located in southern Sweden, (2)\\u000a analysed how the probability of exceeding an approximate CWS as observed in the management unit would change in different\\u000a regions

Kristina Blennow; Erika Olofsson

2008-01-01

40

Impact of wind direction on diurnal and seasonal changes in wind profiles  

Microsoft Academic Search

We explored the relationship between directional variation (changes in direction from a reference point) in vegetation and\\u000a wind profiles, and propose an empirical wind profile model that may reproduce the wind profile within the canopy (such as\\u000a secondary wind maximum) and reduce calculation loads. Based on the results of our observations in secondary broad-leaved forest,\\u000a we clarified the variation in

Kenichi Daikoku; Shigeaki Hattori; Aiko Deguchi; Yuji Fujita; Kazuho Matsumoto

2007-01-01

41

Climate change and vector-borne diseases: a regional analysis.  

PubMed Central

Current evidence suggests that inter-annual and inter-decadal climate variability have a direct influence on the epidemiology of vector-borne diseases. This evidence has been assessed at the continental level in order to determine the possible consequences of the expected future climate change. By 2100 it is estimated that average global temperatures will have risen by 1.0-3.5 degrees C, increasing the likelihood of many vector-borne diseases in new areas. The greatest effect of climate change on transmission is likely to be observed at the extremes of the range of temperatures at which transmission occurs. For many diseases these lie in the range 14-18 degrees C at the lower end and about 35-40 degrees C at the upper end. Malaria and dengue fever are among the most important vector-borne diseases in the tropics and subtropics; Lyme disease is the most common vector-borne disease in the USA and Europe. Encephalitis is also becoming a public health concern. Health risks due to climatic changes will differ between countries that have developed health infrastructures and those that do not. Human settlement patterns in the different regions will influence disease trends. While 70% of the population in South America is urbanized, the proportion in sub-Saharan Africa is less than 45%. Climatic anomalies associated with the El Niño-Southern Oscillation phenomenon and resulting in drought and floods are expected to increase in frequency and intensity. They have been linked to outbreaks of malaria in Africa, Asia and South America. Climate change has far-reaching consequences and touches on all life-support systems. It is therefore a factor that should be placed high among those that affect human health and survival.

Githeko, A. K.; Lindsay, S. W.; Confalonieri, U. E.; Patz, J. A.

2000-01-01

42

Maximum wind speed changes over China  

NASA Astrophysics Data System (ADS)

In this study, the maximum wind speed (WSmax) changes across China from 1956 to 2004 were analyzed based on observed station data, and the changes of WSmax for 2046-2065 and 2080-2099 are projected using three global climate models (GFDL_CM2_0, CCCMA_CGCM3, and MRI_CGCM2) that have participated in the IPCC Fourth Assessment Report (AR4). The observed annual and seasonal WSmax and the frequency of gale days showed obvious declining trends. The annual WSmax decreased by approximately 1.46 m s-1 per decade, and the number of gale days decreased by 3.0 days per decade from 1956 to 2004. The amplitudes of the annual and seasonal WSmax decreases are larger than those of the annual and seasonal average wind speeds (WSavg). The weakening of the East Asian winter and summer monsoons is the cause for the distinct decreases of both WSmax and WSavg over the whole China. The decrease of WSmax in the southeast coastal areas of China is related to the reduced intensity of cold waves in China and the decreasing number (and decreasing intensity) of land-falling typhoons originated in the Northwest Pacific Ocean. The global climate models GFDL_CM2_0, MRI_CGCM2, and EBGCM (the ensemble of above mentioned three global climate models) consistently suggest that the annual and seasonal WSmax values will decrease during 2046-2065 and 2080-2099 relative to 1981-2000. The models also suggest that decreases in WSmax for whole China during 2046-2065 and 2080-2099 are related to both the reduced intensity of cold waves and the reduced intensity of the winter monsoon, and the decrease in WSmax in the southeast coastal areas of China is corresponding to the decreasing number of tropical cyclones over the Northwest Pacific Ocean in the summer during the same periods.

Jiang, Ying; Luo, Yong; Zhao, Zongci

2013-02-01

43

Wave-Vector Dependence of Magnetic-Turbulence Spectra in the Solar Wind  

SciTech Connect

Using four-point measurements of the Cluster spacecraft, the energy distribution was determined for magnetic field fluctuations in the solar wind directly in the three-dimensional wave-vector domain in the range |k|{<=}1.5x10{sup -3} rad/km. The energy distribution exhibits anisotropic features characterized by a prominently extended structure perpendicular to the mean field preferring the ecliptic north direction and also by a moderately extended structure parallel to the mean field. From the three-dimensional energy distribution wave vector anisotropy is estimated with respect to directions parallel and perpendicular to the mean magnetic field, and the result suggests the dominance of quasi-two-dimensional turbulence toward smaller spatial scales.

Narita, Y.; Glassmeier, K.-H.; Sahraoui, F.; Goldstein, M. L. [Institut fuer Geophysik und extraterrestrische Physik, Technische Universitaet Braunschweig, Mendelssohnstrasse 3, D-38106 Braunschweig (Germany); Geospace Physics Laboratory, NASA Goddard Space Flight Center, Code 673, Greenbelt, Maryland 20771 (United States)

2010-04-30

44

Epidemiological impact of vector control. II. Changes in ocular onchocerciasis.  

PubMed

The impact of 10-11 years of successful vector control on ocular onchocerciasis was evaluated in the population of 13 villages in the central part of the Onchocerciasis Control Programme area. The prevalence of ocular microfilariae was found to have reduced remarkably and loads over 20 microfilariae in the anterior chamber of the eye or the cornea which was rampant before the start of vector control, were rare. Whilst limited change in the age specific prevalence of lesions of the posterior segment of the eye was recorded, significant reduction in the prevalence of lesions of the anterior segment of the eye was found. The small decrease in the age specific prevalence of lesions of the posterior segment of the eye was partly explained by a reduced occurrence of the type of lesions of the anterior segment of the eye which previously obstructed the effective view of the fundus during examination. The prevalence of blindness was found to have reduced by 40% and onchocercal blindness was no longer found below the age of 20 years. It was concluded that 10-11 years of successful vector control has effectively reduced the incidence of onchocercal eye lesions, the deterioration of the existing eye lesions and the risk of developing an onchocercal eye lesion as well as going blind to virtually nil. PMID:2378201

Dadzie, K Y; Remme, J; De Sole, G

1990-01-01

45

Wind energy: Developing energy, wealth, and change  

NASA Astrophysics Data System (ADS)

Wind energy has emerged as one of the fastest growing energy sources in the United States over the course of the last decade. It is the renewable energy type most readily defining clean economy leadership. An uncertain policy context, public conflicts over the impacts of turbine installations, and unsorted connections to a national green development strategy raise questions about the continued viability of wind power in the U.S. This thesis attempts to document and question some of the issues raised by wind energy expansion in the U.S. generally, but in Maine in particular, in order to explain how environmental, social, and economic benefits accrue to places hosting wind projects. The available information combined with a targeted inquiry produce insights into how the state of Maine can improve its wind development policies and outcomes.

Hopkins, Matt

46

vectors  

NSDL National Science Digital Library

The word vector comes from the Latin term vehere, to carry. In Biology, a vector is an agent which carries disease, such as a mosquito carrying infected blood from one patient to the next. In physics, a vector is a quantity which has both a magnitude and a direction associated with it. The most commonly used example of vectors in everyday life is velocity. When you drive your car, your speedometer tells you the speed of your car, but it doesn't tell you where you are going. The combination of both where you are going and how fast you are going there is your car's velocity.

Joiner, David; The Shodor Education Foundation, Inc.

47

Using support vector machines for anomalous change detonation  

SciTech Connect

We cast anomalous change detection as a binary classification problem, and use a support vector machine (SVM) to build a detector that does not depend on assumptions about the underlying data distribution. To speed up the computation, our SVM is implemented, in part, on a graphical processing unit. Results on real and simulated anomalous changes are used to compare performance to algorithms which effectively assume a Gaussian distribution. In this paper, we investigate the use of support vector machines (SVMs) with radial basis kernels for finding anomalous changes. Compared to typical applications of SVMs, we are operating in a regime of very low false alarm rate. This means that even for relatively large training sets, the data are quite meager in the regime of operational interest. This drives us to use larger training sets, which in turn places more of a computational burden on the SVM. We initially considered three different approaches to to address the need to work in the very low false alarm rate regime. The first is a standard SVM which is trained at one threshold (where more reliable estimates of false alarm rates are possible) and then re-thresholded for the low false alarm rate regime. The second uses the same thresholding approach, but employs a so-called least squares SVM; here a quadratic (instead of a hinge-based) loss function is employed, and for this model, there are good theoretical arguments in favor of adjusting the threshold in a straightforward manner. The third approach employs a weighted support vector machine, where the weights for the two types of errors (false alarm and missed detection) are automatically adjusted to achieve the desired false alarm rate. We have found in previous experiments (not shown here) that the first two types can in some cases work well, while in other cases they do not. This renders both approaches unreliable for automated change detection. By contrast, the third approach reliably produces good results, but at the cost of larger computational requirements caused by the need to estimate very small false alarm rates. To address these computational requirements, we employ a recently developed in-house solver for SVMs that is significantly faster than freely available standard solvers. But these computational issues are secondary to the larger question: do kernelized solutions provide better performance, in terms of detection rates and false alarm rates, than more traditional methods for change detection that effectively assume Gaussian data distributions? To this end, we will compare ROC curves obtained from the SVM with those from chronochrome, covariance equalization, and hyperbolic anomalous change detection.

Theiler, James P [Los Alamos National Laboratory; Steinwart, Ingo [UNIV STUTTGART; Llamocca, Daniel [UNM

2010-01-01

48

A Theoretical Framework for Unsupervised Change Detection Based on Change Vector Analysis in the Polar Domain  

Microsoft Academic Search

This paper addresses unsupervised change detection by proposing a proper framework for a formal definition and a theoretical study of the change vector analysis (CVA) technique. This framework, which is based on the representation of the CVA in polar coordinates, aims at: 1) introducing a set of formal definitions in the polar domain (which are linked to the properties of

Francesca Bovolo; Lorenzo Bruzzone

2007-01-01

49

Wind Power Production and Climate Change--a Modeling Study  

NASA Astrophysics Data System (ADS)

Recent studies using Global Climate Models (GCMs) for several climate change scenarios are inconclusive as to the sign of the change in surface wind speeds. Some regions may experience a net increase in boundary layer winds, while other areas observe a decrease. Areas within the U.S. that are most susceptible to climate change also contain substantial wind resources (for example, California and the Great Plains). The next few decades under a changing climate may also see greater variation in seasonal and annual wind speeds, making long-term planning for air quality and wind energy purposes problematic. Thus, the purpose of this presentation is to show preliminary results from a regional-scale study focusing on the effects of climate change on wind in the boundary layer. Under the sponsorship of the California Energy Commission (CEC) and the Lawrence Livermore National Laboratory (LLNL), simulations of future-climate (2040-2060) wind speeds in the surface layer were performed in in order to estimate affects upon wind power production under the IPCC A2 greenhouse gas emissions scenario. Output from high-resolution (50 km) global climate simulations conducted at LLNL for the Department of Energy (DOE) National Science Foundation (NSF)-funded North American Regional Climate Change Prediction Project (NARCCAP) was used to initialize AWS Truewind's Mesoscale Atmospheric Simulation System (MASS) model. Simulations covering the entire state of California, with a grid size of 15 km, and "inner nests" with finer resolution (4.0 km) in the Tehachapi Pass and other wind resource regions were performed. We present the results of these simulations and will discuss the implications for future wind energy resource assessment, air dispersion applications, and energy balance consequences.

Freedman, J. M.; Waight, K.; Duffy, P. P.

2008-12-01

50

Evaluation of ASCAT Ocean Surface Vector Wind (OSVW) Retrievals at NOAA OPC  

NASA Astrophysics Data System (ADS)

The National Oceanic and Atmospheric Administration (NOAA) Ocean Prediction Center (OPC) is responsible for issuing marine weather forecasts and wind warnings over the North Atlantic and North Pacific high seas from 35 degrees West to 160 degrees East, including the offshore waters of the continental United States. In providing accurate marine warnings and forecasts, one of the most significant challenges facing an OPC forecaster is the scarcity of data over the vast ocean regions within the OPC's area of responsibility (AOR). The high quality, remotely sensed ocean surface vector wind (OSVW) data greatly help fill in the immense data void between the sparse conventional surface observations within the OPC's AOR. The SeaWinds scatterometer onboard QuikSCAT satellite has been providing the OPC forecasters, and the operational weather community with near real time (NRT) OSVW data since the spring of 2000. Over the eight years of availability, QuikSCAT winds have become an integral data source in OPC daily operations. An additional source of OSVW data has become available in the large and mostly void regions within the OPC's AOR after the recent launch of the Advanced Scatterometer (ASCAT) in October 2006 by EUMETSAT. The OSVW retrievals from ASCAT are produced at two horizontal resolutions of 50 and 25 km by NOAA NESDIS, and have been available to OPC forecasters since June 2007 and October 2007, respectively. The ASCAT wind data is being routinely viewed by OPC forecasters on a daily basis during the course of their operational shifts. Compared to QuikSCAT, the ASCAT instrument has different capabilities, due to ASCAT's coarser resolution, narrower swath, and reduced sensitivity to rain and high wind speeds. In this paper we provide an overview of the ASCAT measurement characteristics, and the instrument spatial / temporal coverage. Further, we present an up to date assessment of the ASCAT retrievals in support of OPC's analysis and warning operations, where we focus on the utility of the ASCAT OSVW data in detecting Hurricane Force (HF) extratropical cyclones, and estimating the wind warning category. In this activity, we utilize the surface analysis charts prepared by the OPC forecasters to locate and track all HF extratropical cyclones observed over both the North Atlantic and North Pacific oceans during the period from Oct'07 ~ May'08 of the last winter season. Hundreds of passes from ASCAT and QuikSCAT are examined, and wind retrievals are compared to the output of two Numerical Weather Prediction (NWP) models, and where available, to conventional buoy / ship observations. Results indicate that ASCAT can reliably retrieve low to moderate surface wind speeds in all weather conditions. This performance represents an improvement over QuikSCAT, which suffers from an artificially rain inflated retrievals in areas of rain. However, for higher wind speeds, ASCAT retrievals are found to have a low wind speed bias, which degrades the ASCAT capability in detecting extratropical cyclones with Hurricane Force conditions.

Ahmad, K. A.; Sienkiewicz, J. M.

2008-12-01

51

Space vector PWM for a direct matrix converter based open-end winding ac drives with enhanced capabilities  

Microsoft Academic Search

This paper introduces a space vector PWM technique for a direct matrix converter based three-phase open-end winding AC machine drive. With the proposed PWM technique, the following simultaneous capabilities of the open-end winding drive system are achieved: 1) Machine phase voltage up to 1.5 times the input phase voltage in the linear modulation, 2) Controllable grid power factor, and 3)

Ranjan K. Gupta; Apurva Somani; Krushna K. Mohapatra; Ned Mohan

2010-01-01

52

Self-adjusting and fuzzy logic gain schedulers for vector control of wind driven doubly-fed induction generator  

Microsoft Academic Search

Wind is one of the most efficient renewable energy sources available. Wound-rotor induction generators, specifically the doubly-fed induction generator, have numerous advantages in wind power generation in comparison to other generators. Doubly-fed induction generators use a converter cascade between the slip-ring terminals and the utility grid to control the rotor power. A vector control scheme developed to control the rotor

Hany M. Jabr; Lakshmi Varaha Iyer; Chitradeep Sen; Narayan C. Kar

2012-01-01

53

Vectors  

NSDL National Science Digital Library

This web page introduces vectors as an extension of numbers having both magnitude and direction. The initial motivation is to describe velocity but the material includes a general discussion of vector algebra and an application to forces for the inclined plane. The page contains links to a related lesson plan and further opportunities to explore vectors. This is part of the extensive web site "From Stargazers to Starships", that uses space exploration and space science to introduce topics in physics and astronomy. Translations in Spanish and French are available.

Stern, David

2006-07-16

54

Indian MST radar 1. System description and sample vector wind measurements in ST mode  

NASA Astrophysics Data System (ADS)

An MST radar operating at 53 MHz with an average power aperture product of 7 × 108 W m2 has been established at Gadanki (13.5°N, 79.2°E), India. The radar development has been accomplished in two phases. In the first phase it was commissioned in ST mode using a partial system comprising one quarter (16 × 16)of the Yagi antenna array and 16 driver units of the transmitters providing an average power aperture product of 4.8 × 106 W m2. In this part we present the radar system description, including off-line data processing, and some sample high-resolution vector wind measurements made in ST mode operation.

Rao, P. B.; Jain, A. R.; Kishore, P.; Balamuralidhar, P.; Damle, S. H.; Viswanathan, G.

1995-07-01

55

Wind energy: Developing energy, wealth, and change  

Microsoft Academic Search

Wind energy has emerged as one of the fastest growing energy sources in the United States over the course of the last decade. It is the renewable energy type most readily defining clean economy leadership. An uncertain policy context, public conflicts over the impacts of turbine installations, and unsorted connections to a national green development strategy raise questions about the

Matt Hopkins

2010-01-01

56

Genomic Changes of Chagas Disease Vector, South America  

PubMed Central

We analyzed the main karyologic changes that have occurred during the dispersion of Triatoma infestans, the main vector of Chagas disease. We identified two allopatric groups, named Andean and non-Andean. The Andean specimens present C-heterochromatic blocks in most of their 22 chromosomes, whereas non-Andean specimens have only 4–7 autosomes with C-banding. These heterochromatin differences are the likely cause of a striking DNA content variation (approximately 30%) between Andean and non-Andean insects. Our study, together with previous historical and genetic data, suggests that T. infestans was originally a sylvatic species, with large quantities of DNA and heterochromatin, inhabiting the Andean region of Bolivia. However, the spread of domestic T. infestans throughout the non-Andean regions only involved insects with an important reduction of heterochromatin and DNA amounts. We propose that heterochromatin and DNA variation mainly reflected adaptive genomic changes that contribute to the ability of T. infestans to survive, reproduce, and disperse in different environments.

Dujardin, Jean Pierre; Nicolini, Paula; Caraccio, Maria Noel; Rose, Virginia; Tellez, Tatiana; Bermudez, Hernan; Bargues, Maria Dolores; Mas-Coma, Santiago; O'Connor, Jose Enrique; Perez, Ruben

2004-01-01

57

Genomic changes of Chagas disease vector, South America.  

PubMed

We analyzed the main karyologic changes that have occurred during the dispersion of Triatoma infestans, the main vector of Chagas disease. We identified two allopatric groups, named Andean and non-Andean. The Andean specimens present C-heterochromatic blocks in most of their 22 chromosomes, whereas non-Andean specimens have only 4-7 autosomes with C-banding. These heterochromatin differences are the likely cause of a striking DNA content variation (approximately 30%) between Andean and non-Andean insects. Our study, together with previous historical and genetic data, suggests that T. infestans was originally a sylvatic species, with large quantities of DNA and heterochromatin, inhabiting the Andean region of Bolivia. However, the spread of domestic T. infestans throughout the non-Andean regions only involved insects with an important reduction of heterochromatin and DNA amounts. We propose that heterochromatin and DNA variation mainly reflected adaptive genomic changes that contribute to the ability of T. infestans to survive, reproduce, and disperse in different environments. PMID:15109410

Panzera, Francisco; Dujardin, Jean Pierre; Nicolini, Paula; Caraccio, María Noel; Rose, Virginia; Tellez, Tatiana; Bermúdez, Hernán; Bargues, María Dolores; Mas-Coma, Santiago; O'Connor, José Enrique; Pérez, Ruben

2004-03-01

58

Solar wind mechanism suggested for weather and climate change  

Microsoft Academic Search

It was suggested by Sir William Herschel about 200 years ago that changes in the growing season for wheat in England could be related to the 11-year sunspot cycle. He speculated that there was a change in the luminosity of the Sun that was correlated with the sunspot variation, and that it affected precipitation and the winds. As discussed recently

Brian A. Tinsley

1994-01-01

59

Vector velocity profiles of the solar wind within expanding magnetic clouds at 1 AU: Some surprises  

NASA Astrophysics Data System (ADS)

We investigated the average vector velocity profile of 36 carefully chosen WIND interplanetary magnetic clouds occurring over about a 7 year period since spacecraft launch, to see if a differential pattern of solar wind flow exists. Particular cases were chosen of clouds whose axes were generally within 45 degrees of the ecliptic plane and of relatively well determined characteristics obtained from cloud-parameter (cylindrically symmetric force free) fitting. This study was motivated by the desire to understand the manner in which magnetic clouds expand, a well know phenomenon revealed by most cloud speed-profiles at 1 AU. One unexpected and major result was that, even though cloud expansion was confirmed, it was primarily along the Xgse axis; i.e., neither the Ygse or Zgse velocity components reveal any noteworthy pattern. After splitting the full set of clouds into a north-passing set (spacecraft passing above the cloud, where Nn = 21) and south-passing set (Ns = 15), to study the plasma expansion of the clouds with respect to the position of the observer, it was seen that the Xgse component of velocity differs for these two sets in a rather uniform and measurable way for most of the average cloud's extent. This does not appear to be the case for the Ygse or Zgse velocity components where little measurable differences exists, and clearly no pattern, across the average cloud between the north and south positions. It is not clear why such a remarkably non-axisymmetric plasma flow pattern within the "average magnetic cloud" at 1 AU should exist. The study continues from the perspective of magnetic cloud coordinate representation. ~ ~ ~

Wu, C.; Lepping, R. P.; Berdichevsky, D.; Ferguson, T.; Lazarus, A. J.

2002-12-01

60

The hourly average solar wind velocity prediction based on support vector regression method  

NASA Astrophysics Data System (ADS)

A new neural network technique, support vector regression (SVR), is applied to forecast the solar wind (SW) velocity. SVR is a non-linear efficient tool for high data processing based on statistical learning theory. Its advantage is that the input only requires several periods data (about four 27-d solar-rotation periods to SW velocity prediction in this study), and the prediction is quite reliable. In our work, we deliberately choose the typical SW data covering all main space weather conditions: the SW data during the 9 yr from 1998 to 2006, which includes the periods of the SW speed variation associated with high-speed streams from coronal hole and coronal mass ejections. The performance of the SVR is measured by calculating the absolute average fractional deviation and correlation coefficient between the SVR model and observed SW velocity. We find that the predicted velocity values are over 90 per cent of the observed ones, i.e. the new approach is accurate and reliable in forecasting SW velocity. Based on the error difference, it can be concluded that the SVR technique can lend itself to future space weather forecasting models.

Liu, D. D.; Huang, C.; Lu, J. Y.; Wang, J. S.

2011-06-01

61

Indicators of land-cover change for change-vector analysis in multitemporal space at coarse spatial scales  

Microsoft Academic Search

Change-vector analysis in multi-temporal space is a powerful tool to analyse the nature and magnitude of land-cover change. The change vector compares the difference in the time-trajectory of a biophysical indicator for successive time periods. This change detection method is applied to three remotely-sensed indicators of land-surface conditions—vegetation index, surface temperature and spatial structure—in order to improve the capability to

E. F. LAMBIN; A. H. STRAHLER

1994-01-01

62

Design and Implementation of Neuro-Fuzzy Vector Control for Wind-Driven Doubly-Fed Induction Generator  

Microsoft Academic Search

Wound-rotor induction generators have numerous advantages in wind power generation over other types of gener- ators. One scheme is realized when a converter cascade is used between the slip-ring terminals and the utility grid to control the rotor power. This configuration is called the doubly-fed induction generator (DFIG). In this paper, a vector control scheme is devel- oped to control

Hany M. Jabr; Dongyun Lu; Narayan C. Kar

2011-01-01

63

Magnetic energy distribution in the four-dimensional frequency and wave vector domain in the solar wind  

NASA Astrophysics Data System (ADS)

We present a measurement of the energy distribution in the four-dimensional (4-D) frequency and wave vector domain of magnetic field fluctuations in the solar wind. The measurement makes use of the wave telescope technique that has been developed particularly for multispacecraft data analysis. We review briefly the theoretical background and then present a numerical test using synthetic data; the technique is then applied to magnetic field data obtained while the Cluster spacecraft was in the solar wind. The energy distribution is determined in the flow rest frame in the frequency range below 0.2 rad/s and the wave number range below 0.0015 rad/km, corrected for the Doppler shift. We find the following properties in the energy distribution in the rest frame: (1) a double anisotropy in the wave vector domain associated with the mean magnetic field and the flow directions, (2) a symmetric distribution with respect to the sign of wave vector, and (3) no evidence for a linear dispersion relation in the frequency and wave number domain. Since the flow direction in the analyzed time interval is close to the normal direction to the bow shock, the anisotropy may well be associated with the bow shock. These results suggest that the solar wind is in a state of well-developed strong turbulence and justifies the theoretical picture of quasi-two-dimensional turbulence that obtains in the presence of a (relatively) strong DC magnetic field. However, the fluctuations are not axisymmetric around the mean field and the energy distribution is extended in the perpendicular direction to the flow or shock normal. Anisotropy associated with the boundary is reminiscent of previously reported magnetosheath turbulence. This study opens a way to investigate solar wind turbulence in the full 4-D frequency and wave vector space.

Narita, Y.; Sahraoui, F.; Goldstein, M. L.; Glassmeier, K.-H.

2010-04-01

64

Evaluation of turbulent magnetic energy spectra in the three-dimensional wave vector domain in the solar wind  

SciTech Connect

Using four-point measurements of the CLUSTER spacecraft, the energy distribution of magnetic field fluctuations in the solar wind is determined directly in the three-dimensional wave vector domain in the range 3 x 10{sup -4} rad/km < k < 3 x 10{sup -3} rad/km. The analysis method takes account of a regular tetrahedron configuration of CLUSTER and the Doppler effect. The energy distribution in the flow rest frame is anisotropic, characterized by two distinct extended structures perpendicular to the mean magnetic field and furthermore perpendicular to the flow direction. The three-dimensional distribution is averaged around the direction of the mean magnetic field direction, and then is further reduced to one-dimensional distributions in the wave number domain parallel and perpendicular to the mean magnetic field. The one-dimensional energy spectra are characterized by the power law with the index -5/3 and furthermore very close energy density between parallel and perpendicular directions to the mean magnetic field at the same wave numbers. Though the distributions and the spectra are not covered in a wide range of wave vectors, our measurements suggest that the solar wind fluctuation is anisotropic in the three-dimensional wave vector space. It is, however, rather isotropic when reduced into the parallel and perpendicular wave vector geometries due to the second anisotropy imposed by the flow direction.

Gary, S Peter [Los Alamos National Laboratory; Narita, Y [UNIV OF BRAUNSCHWEIG; Glassmeier, K H [UNIV OF BRAUNSCHWEIG; Goldstein, M L [NGSFC; Safraoui, F [NGSFC; Treumann, R A [UNIV. MUNICH

2009-01-01

65

Effects of Local Anthropogenic Changes on Potential Malaria Vector Anopheles hyrcanus and West Nile Virus Vector Culex modestus, Camargue, France  

PubMed Central

Using historical data, we highlight the consequences of anthropogenic ecosystem modifications on the abundance of mosquitoes implicated as the current most important potential malaria vector, Anopheles hyrcanus, and the most important West Nile virus (WNV) vector, Culex modestus, in the Camargue region, France. From World War II to 1971, populations of these species increased as rice cultivation expanded in the region in a political context that supported agriculture. They then fell, likely because of decreased cultivation and increased pesticide use to control a rice pest. The species increased again after 2000 with the advent of more targeted pest-management strategies, mainly the results of European regulations decisions. An intertwined influence of political context, environmental constraints, technical improvements, and social factors led to changes in mosquito abundance that had potential consequences on malaria and WNV transmission. These findings suggest that anthropogenic changes should not be underestimated in vectorborne disease recrudescence.

Poncon, Nicolas; Balenghien, Thomas; Toty, Celine; Ferre, Jean Baptiste; Thomas, Cyrille; Dervieux, Alain; L'Ambert, Gregory; Schaffner, Francis; Bardin, Olivier

2007-01-01

66

Mediterranean cyclones and wind storms in a changing climate  

NASA Astrophysics Data System (ADS)

This study examines cyclones and related wind storms affecting the Mediterranean region under present-day and future climate scenario conditions. The analysis is based on seven coupled ocean atmosphere GCM simulations: one simulation with the high resolution INGV CMCC GCM which was especially designed for Mediterranean applications, covering the period from 1950 to 2050 and was driven by observed and SRES A1B greenhouse gas concentrations; and six simulations with the ECHAM5/MPI-OM GCM encompassing the period from 1960-2100 following historic and SRES A1B (3 simulations) or SRES A2 (3 simulations) greenhouse gas levels. Cyclones are detected using an objective cyclone identification and tracking algorithm. The intensity of cyclones is determined based on their Laplacian of pressure. Wind storms are detected by identifying clusters with wind speeds exceeding the local 98th percentile, which are than tracked in time using a nearest neighbour approach. The strength of a wind storm event is expressed via a storm severity index, which takes both area and duration of its extreme wind speeds into account. In all climate change integrations, the total number of cyclones over the Mediterranean region significantly decreases in future decades. The decrease is especially high for intense cyclones (Laplacian of pressure >1.5; i.e. strongest 5%). However, for the most extreme cyclones, with return periods greater than a year and values of the Laplacian of pressure above 2 (corresponding to the strongest 0.1%), no statistically significant change in the frequency can be detected. In terms of wind storms, their number exhibits a statistically significant decrease over most of the Mediterranean Basin. Again, the frequency of the most extreme wind tracks does not change significantly. It is shown that the majority of these most extreme cyclones are not of local origin but move into the Mediterranean region from the Atlantic Ocean. This is also true for extreme wind storms, which are mostly associated with cyclones that pass outside of the Mediterranean region. Most affected areas by these events are the Bay of Biscay and the Northern Mediterranean region.

Nissen, K. M.; Ulbrich, U.; Leckebusch, G. C.; Pinto, J. G.

2012-04-01

67

3D visualization of solar wind ion data from the Chang'E-1 exploration  

Microsoft Academic Search

Chang'E-1 (abbreviation CE-1), China's first Moon-orbiting spacecraft launched in 2007, carried equipment called the Solar Wind Ion Detector (abbreviation SWID), which sent back tens of gigabytes of solar wind ion differential number flux data. These data are essential for furthering our understanding of the cislunar space environment. However, to fully comprehend and analyze these data presents considerable difficulties, not only

Tian Zhang; Yankui Sun; Zesheng Tang

2011-01-01

68

An Analysis of Climate Change Impacts on Future Wind Energy Production in California  

Microsoft Academic Search

Future climate change is expected to change the spatial and temporal distribution of surface wind speeds (SWS), with associated impacts on electricity generation from wind energy. However, the direction and magnitude of that change is not robust at the three largest wind farm sites in California. This study uses the North American Regional Climate Change Assessment Program's (NARCCAP) downscaled climate

D. M. Rasmussen; T. Holloway; G. F. Nemet

2010-01-01

69

A Vector Control for Grid-connected Wind Power Generation with Doubly Fed Induction Generator  

Microsoft Academic Search

Recently, doubly fed induction generator (DFIG) and synchronous generator are mostly applied for wind power generation due to high efficiently for wind energy capture. An inverter system is required to control wind turbine speed and power factor in those generators. The inverter rating of the synchronous generator equals to generator rating. However, DFIG has the advantage that the inverter rating

Takaaki Kai; Yuji Tanaka; Hirotoshi Kaneda; Daichi Kobayashi; Akio Tanaka

2008-01-01

70

Predicting the effect of climate change on African trypanosomiasis: integrating epidemiology with parasite and vector biology  

PubMed Central

Climate warming over the next century is expected to have a large impact on the interactions between pathogens and their animal and human hosts. Vector-borne diseases are particularly sensitive to warming because temperature changes can alter vector development rates, shift their geographical distribution and alter transmission dynamics. For this reason, African trypanosomiasis (sleeping sickness), a vector-borne disease of humans and animals, was recently identified as one of the 12 infectious diseases likely to spread owing to climate change. We combine a variety of direct effects of temperature on vector ecology, vector biology and vector–parasite interactions via a disease transmission model and extrapolate the potential compounding effects of projected warming on the epidemiology of African trypanosomiasis. The model predicts that epidemics can occur when mean temperatures are between 20.7°C and 26.1°C. Our model does not predict a large-range expansion, but rather a large shift of up to 60 per cent in the geographical extent of the range. The model also predicts that 46–77 million additional people may be at risk of exposure by 2090. Future research could expand our analysis to include other environmental factors that influence tsetse populations and disease transmission such as humidity, as well as changes to human, livestock and wildlife distributions. The modelling approach presented here provides a framework for using the climate-sensitive aspects of vector and pathogen biology to predict changes in disease prevalence and risk owing to climate change.

Moore, Sean; Shrestha, Sourya; Tomlinson, Kyle W.; Vuong, Holly

2012-01-01

71

Predicting the effect of climate change on African trypanosomiasis: integrating epidemiology with parasite and vector biology.  

PubMed

Climate warming over the next century is expected to have a large impact on the interactions between pathogens and their animal and human hosts. Vector-borne diseases are particularly sensitive to warming because temperature changes can alter vector development rates, shift their geographical distribution and alter transmission dynamics. For this reason, African trypanosomiasis (sleeping sickness), a vector-borne disease of humans and animals, was recently identified as one of the 12 infectious diseases likely to spread owing to climate change. We combine a variety of direct effects of temperature on vector ecology, vector biology and vector-parasite interactions via a disease transmission model and extrapolate the potential compounding effects of projected warming on the epidemiology of African trypanosomiasis. The model predicts that epidemics can occur when mean temperatures are between 20.7°C and 26.1°C. Our model does not predict a large-range expansion, but rather a large shift of up to 60 per cent in the geographical extent of the range. The model also predicts that 46-77 million additional people may be at risk of exposure by 2090. Future research could expand our analysis to include other environmental factors that influence tsetse populations and disease transmission such as humidity, as well as changes to human, livestock and wildlife distributions. The modelling approach presented here provides a framework for using the climate-sensitive aspects of vector and pathogen biology to predict changes in disease prevalence and risk owing to climate change. PMID:22072451

Moore, Sean; Shrestha, Sourya; Tomlinson, Kyle W; Vuong, Holly

2011-11-09

72

Vector Voyage!  

NSDL National Science Digital Library

In this activity, students will use vector analysis to understand the concept of dead reckoning. Students will use vectors to plot their course based on a time and speed. They will then correct the positions with vectors representing winds and currents.

Integrated Teaching And Learning Program

73

Combining Climatic Projections and Dispersal Ability: A Method for Estimating the Responses of Sandfly Vector Species to Climate Change  

PubMed Central

Background In the Old World, sandfly species of the genus Phlebotomus are known vectors of Leishmania, Bartonella and several viruses. Recent sandfly catches and autochthonous cases of leishmaniasis hint on spreading tendencies of the vectors towards Central Europe. However, studies addressing potential future distribution of sandflies in the light of a changing European climate are missing. Methodology Here, we modelled bioclimatic envelopes using MaxEnt for five species with proven or assumed vector competence for Leishmania infantum, which are either predominantly located in (south-) western (Phlebotomus ariasi, P. mascittii and P. perniciosus) or south-eastern Europe (P. neglectus and P. perfiliewi). The determined bioclimatic envelopes were transferred to two climate change scenarios (A1B and B1) for Central Europe (Austria, Germany and Switzerland) using data of the regional climate model COSMO-CLM. We detected the most likely way of natural dispersal (“least-cost path”) for each species and hence determined the accessibility of potential future climatically suitable habitats by integrating landscape features, projected changes in climatic suitability and wind speed. Results and Relevance Results indicate that the Central European climate will become increasingly suitable especially for those vector species with a current south-western focus of distribution. In general, the highest suitability of Central Europe is projected for all species in the second half of the 21st century, except for P. perfiliewi. Nevertheless, we show that sandflies will hardly be able to occupy their climatically suitable habitats entirely, due to their limited natural dispersal ability. A northward spread of species with south-eastern focus of distribution may be constrained but not completely avoided by the Alps. Our results can be used to install specific monitoring systems to the projected risk zones of potential sandfly establishment. This is urgently needed for adaptation and coping strategies against the emerging spread of sandfly-borne diseases.

Fischer, Dominik; Moeller, Philipp; Thomas, Stephanie M.; Naucke, Torsten J.; Beierkuhnlein, Carl

2011-01-01

74

Estimated changes in wind speed and wind power density over the western High Plains, 1971-2000  

NASA Astrophysics Data System (ADS)

This manuscript presents the results of research on the temporal patterns in wind speed and wind power density from 1971 to 2000. The study area is across the western High Plains states east of the Rocky Mountains in an area which has a proven wind power resource. Policies and economic analyses involving the rapidly expanding wind power industry have often assumed a constant in the wind resource; however, any temporal pattern or trend in wind speeds can have a meaningful impact on the reliability of wind power as an energy resource. Using data provided by the North American Regional Climate Change Assessment Program (NARCCAP) to analyze decadal and seasonal trends of wind data, this study shows that from 1971 to 2000 there were some notable changes in the NARCCAP simulated wind velocities over the study region. Wind speed trends across the central High Plains of the USA were most notable across the western portion of the study area along the higher terrain near the front range of the Rocky Mountains. The most significant changes occurred during winter and spring when a large portion of the study area experienced the most substantial decrease in wind speed, with a 20% reduction in wind power density during spring across the western portion of the study area. During summer and fall, the trends are less noticeable, with only very small changes in the summer. Fall was the only season that saw widespread increased values of wind power density from the 1970s to 1990s, with increases of nearly 10% in some southern areas of the study area. Based upon the analysis of the data and previous literature, it is theorized that these changes could be the result of changing synoptic patterns across the study region.

Greene, J. Scott; Chatelain, Matthew; Morrissey, Mark; Stadler, Steve

2012-08-01

75

Simulation and Assessment of a Ku-Band Full-Polarized Radar Scatterometer for Ocean Surface Vector Wind Measurement  

NASA Astrophysics Data System (ADS)

Spaceborne radar scatterometry is the most important tool for global ocean surface wind vector (OSVW) measurement. Performances under condition of high-wind speed and accuracy of wind direction retrievals are two very important concerns for the development of OSVW measurement techniques by radar scatterometry. Co-polarized sigma 0 measurements are employed, for all the spaceborne radar scatterometers developed in past, and future planned missions. The main disadvantages of co-polarized only radar scatterometers for OSVW measurement are: firstly, wind vector retrieval performances varies with the position of the wind vector cells (WVC) within the swath, where WVCs with small incident angels with weaker modulation effect between sigma0 and azimuth incident angle, and the WVCs located in the outer part of the swath with lower signal-to-noise ratio and lower radiometric accuracies, have worse retrieval performances; secondly, for co-polarization measurements, Sigma 0 is the even function of the azimuth incident angle with respect to the real wind direction, which can results in directional ambiguity, and more additional information is need for the ambiguity removal. Theoretical and experimental results show that the cross-polarization measurement can provide complementary directional information to the co-polarization measurements, which can provide useful improvement to the wind vector retrieval performances. In this paper, the simulation and performance assessment of a full-polarized Ku-band radar scatterometer are provided. Some important conclusions are obtained: (1) Compared with available dual co-polarized radar scatterometer, the introduction of cross-polarization information can significantly improve the OSVW retrieval accuracies, where a relatively identical performance can be obtained within the whole swath. Simulation show that without significantly power increase, system design based on rotating-pencil beam design has much better performances than rotation fan-beam system due to its higher antenna gain and signal-to-noise ratio; (2) The performances of the full-polarized measurement, where all the 9 element covariant coefficient elements will be measurement, only have a little improvement compared with the "dual-co-polarization+HVVV" design, which is because of the almost identical characteristics of HVVV and VHHH measurement due to reciprocity; (3) The propagation error of rotation pencil-beam system is obviously much smaller than that of the rotation fan-beam system, which is due to the significant difference of antenna gains and signal-to-noise ratios; (4) Introduction of cross-polarized HVVV measurement can lead to almost identical wind direction retrieval performance for both the rotation pencil-beam and rotation fan-beam systems, which show that the cross-polarization information can significantly improve the wind direction retrieval performances by increasing the number of look angles, compared with the available fixed-fan-beam systems.

Dong, X.; Lin, W.; Zhu, D.; Song, Z.

2011-12-01

76

Method for changing removable bearing for a wind turbine generator  

DOEpatents

A wind generator having removable change-out bearings includes a rotor and a stator, locking bolts configured to lock the rotor and stator, a removable bearing sub-assembly having at least one shrunk-on bearing installed, and removable mounting bolts configured to engage the bearing sub-assembly and to allow the removable bearing sub-assembly to be removed when the removable mounting bolts are removed.

Bagepalli, Bharat Sampathkumaran (Niskayuna, NY); Jansen, Patrick Lee (Scotia, NY); Gadre, Aniruddha Dattatraya (Rexford, NY)

2008-04-22

77

Impacts of past and future climate change on wind energy resources in the United States  

Microsoft Academic Search

The links between climate change and trends in wind energy resources have important potential implications for the wind energy industry, and have received significant attention in recent studies. We have conducted two studies that provide insights into the potential for climate change to affect future wind power production. In one experiment, we projected changes in power capacity for a hypothetical

J. R. McCaa; A. Wood; S. Eichelberger; K. Westrick

2009-01-01

78

Evaluating and modelling the response of an individual to a sudden change in wind speed  

Microsoft Academic Search

The response of an individual to a sudden increase in wind velocity is important in terms of wind comfort and wind safety. This paper is concerned with the latter issue and outlines a series of physical and numerical experiments undertaken in order to evaluate the response of an individual to a sudden change in wind speed. The physical experiments were

S. C. Jordan; T. Johnson; M. Sterling; C. J. Baker

2008-01-01

79

Vectorized difference schemes for a three dimensional enthalpy formulation for phase change problems  

SciTech Connect

Fully vectorized codes have been written for the CRAY X-MP implementing explicit and implicit finite difference schemes for enthalpy formulations of three dimensional Stefan-like problems. The implicit scheme is that proposed by C.M. Elliot and J.R. Ockendon. The explicit scheme is intended to provide a comparison for the results from the implicit scheme. Vectorization of the code required some ingenuity since material properties change discontinuously as solidification proceeds. Boolean variables were used to avoid conditional branches in DO loops. Average vector length was greatly increased by unfolding three dimensional arrays and treating them as long vectors. This report documents the development of the code and the vectorization strategies. The investigation of the tradeoffs between the implicit scheme, potentially capable of taking large time steps, and the explicit scheme, whose time step size is limited by the stability criterion, has begun but is not complete. 4 refs., 6 figs.

Williams, M.A.; Wilson, D.G.

1986-07-01

80

Observed surface and upper-air wind speed changes over China since 1960  

NASA Astrophysics Data System (ADS)

Previous studies indicated that surface wind speed over China became weakening during past decades, and several explanations exist in the literature. This study presents the longer-term (1960-2009) changes of both surface and upper-air wind speed as well as observed surface and upper-air evidences accounting for the wind speed change. According to our analyses, the surface wind over China underwent a three-phase change during the past 50 years: strengthened before 1974, then weakened till 2002, and turned to be steady during recent years. The variability of surface wind speed is greater at higher elevations and less at lower elevations. Accordingly, surface wind speed over the elevated Tibetan Plateau has changed more rapidly during both the strengthening and the weakening phases, and turned to be increasing during recent years. The upper-air wind speed changes observed from rawinsonde was similar to surface wind change. Both radiosonde data and NCEP/NCAR reanalysis data indicate that the wind speed changes are consistent with the changes in geopotential height gradients at 500 hPa surface. Based on all these analyses, the background of adjustment of general circulation to pressure gradient force was regarded as the main cause of the changes in surface wind speed in China most likely. The recovery of wind speed over the Tibetan Plateau might be a precursor of the reversal of wind speed trend over China, as the Plateau can respond more rapidly to the atmospheric circulation change.

Lin, C.; Yang, K.; Qin, J.

2012-04-01

81

Performance evaluation of space vector modulation controlled inverter fed variable speed wind generator during permanent fault  

Microsoft Academic Search

This paper presents low voltage ride through (LVRT) characteristics analysis of variable speed wind turbine (VSWT) driving a permanent magnet synchronous generator (PMSG). The VSWT-PMSG is becoming very popular these days in wind power application. In some recent studies, the transient stability and LVRT characteristic of VSWT-PMSG has been reported using different types of symmetrical and unsymmetrical faults. However, this

S. M. Muyeen; J. Tamura

2010-01-01

82

Possible Impacts of Climate Change on Wind Gust under Downscaled Future Climate Conditions over Ontario, Canada  

Microsoft Academic Search

The overarching purpose of this study was to project changes in the occurrence frequency and magnitude of future wind gust events under downscaled future climate conditions over Ontario, Canada. Wind gust factors were employed to simulate hourly\\/daily wind gust based on hourly\\/daily wind speed. Regression-based downscaling methods were used to downscale future hourly\\/daily wind speed to each of the 14

Chad Shouquan Cheng; Guilong Li

2010-01-01

83

Model projected changes of extreme wind events in response to global warming  

Microsoft Academic Search

The changes in the frequency of occurrence of extreme wind storm events in response to anthropogenic global warming are explored using a multi-model ensemble of coupled climate model simulations. These changes, diagnosed using several different metrics based on the daily wind fields, indicate that the frequency of the most extreme wind events decreases over the tropics in association with the

G. Gastineau; B. J. Soden

2009-01-01

84

Changes in wind regime around a nickel-copper smelter at Monchegorsk, northwestern Russia  

Microsoft Academic Search

. Wind stress may significantly change plant damage by aerial pollutants. However, almost no information exists on pollution-induced changes in wind regime around the strong emission sources. Wind speed, measured in industrial barrens adjacent to the nickel-copper smelter at Monchegorsk (Kola Peninsula, NW Russia), was two to three times as high as in the slightly polluted and nearly unpolluted forests.

M. V. Kozlov

2002-01-01

85

Changes in near-surface wind speed in China: 1969-2005  

Microsoft Academic Search

This study extends upon previous analyses and details near-surface wind speed change in China and its monsoon regions from 1969 to 2005, using a new dataset consisting of 652 stations. Moreover, causes of wind speed changes are examined. Major results show that most stations in China have experienced significant weakening in annual and seasonal mean wind during the study period.

Hua Guo; Ming Xu; Qi Hu

2011-01-01

86

Buoy perspective of a high-resolution global ocean vector wind analysis constructed from passive radiometers and active scatterometers (1987-present)  

NASA Astrophysics Data System (ADS)

The study used 126 buoy time series as a benchmark to evaluate a satellite-based daily, 0.25-degree gridded global ocean surface vector wind analysis developed by the Objectively Analyzed airs-sea Fluxes (OAFlux) project. The OAFlux winds were produced from synthesizing wind speed and direction retrievals from 12 sensors acquired during the satellite era from July 1987 onward. The 12 sensors included scatterometers (QuikSCAT and ASCAT), passive microwave radiometers (AMSRE, SSMI and SSMIS series), and the passive polarimetric microwave radiometer from WindSat. Accuracy and consistency of the OAFlux time series are the key issues examined here. A total of 168,836 daily buoy measurements were assembled from 126 buoys, including both active and archive sites deployed during 1988-2010. With 106 buoys from the tropical array network, the buoy winds are a good reference for wind speeds in low and mid-range. The buoy comparison shows that OAFlux wind speed has a mean difference of -0.13 ms-1 and an RMS difference of 0.71 ms-1, and wind direction has a mean difference of -0.55 degree and an RMS difference of 17 degrees. Vector correlation of OAFlux and buoy winds is of 0.9 and higher over almost all the sites. Influence of surface currents on the OAFlux/buoy mean difference pattern is displayed in the tropical Pacific, with higher (lower) OAFlux wind speed in regions where wind and current have the opposite (same) sign. Improved representation of daily wind variability by the OAFlux synthesis is suggested, and a decadal signal in global wind speed is evident.

Yu, Lisan; Jin, Xiangze

2012-11-01

87

Fuzzy logic based indirect vector control of induction generator in Wind Energy Conversion System  

Microsoft Academic Search

In order to meet increasing power demand, taking into account economical and environmental factors, wind energy conversion is gradually gaining interest as a suitable source of renewable energy. The modeling of Wind Energy Conversion System(WECS) is done in MATLAB-SIMULINK. The dynamic d-q model of the induction generator is developed from the fundamentals in a modular approach in simulink. A fuzzy

Y. Sreenivasa Rao; A. Jaya Laxmi

2012-01-01

88

Vector Wind Velocity, Speed, and Mode Summaries for the Southeastern U.S.  

National Technical Information Service (NTIS)

This report presents wind speed and direction summaries for a wide area of the Southeastern United States (including EPA Region 4) and portions of the Ohio and Mississippi River Valleys in a monthly time series format that is further broken down for eight...

2004-01-01

89

Modified vector control algorithm for increasing partial-load efficiency of fractional-slot concentrated-winding surface PM machines  

SciTech Connect

This paper presents a modified vector control algorithm for a fractional-slot concentrated-winding surface PM machine that has been developed to maximize the machine's partial-load efficiency over a wide range of operating conditions. By increasing the amplitude of the negative d-axis current, the resulting increase in the stator copper losses can be more than offset by the reduction in the iron core losses achieved by lowering the stator d-axis flux amplitude. The effectiveness of this technique has been demonstrated using both analytical models and finite element analysis (FEA) for a 55 kW (peak) surface PM machine design developed for a demanding set of traction drive performance requirements. For this example, the modified control strategy increases the partial-load efficiency at 20% of rated torque by >6% at 2000 rpm compared to the maximum torque/amp algorithm, making the machine much more attractive for its intended application

El-Refaie, Ayman M [ORNL; Jahns, Thomas M [ORNL; Reddy, Patel [University of Wisconsin; McKeever, John W [ORNL

2006-01-01

90

Successful malaria elimination strategies require interventions that target changing vector behaviours  

PubMed Central

Background The ultimate long-term goal of malaria eradication was recently placed back onto the global health agenda. When planning for this goal, it is important to remember why the original Global Malaria Eradication Programme (GMEP), conducted with DDT-based indoor residual spraying (IRS), did not achieve its goals. One of the technical reasons for the failure to eliminate malaria was over reliance on a single intervention and subsequently the mosquito vectors developed behavioural resistance so that they did not come into physical contact with the insecticide. Hypothesis and how to test it Currently, there remains a monolithic reliance on indoor vector control. It is hypothesized that an outcome of long-term, widespread control is that vector populations will change over time, either in the form of physiological resistance, changes in the relative species composition or behavioural resistance. The potential for, and consequences of, behavioural resistance was explored by reviewing the literature regarding vector behaviour in the southwest Pacific. Discussion Here, two of the primary vectors that were highly endophagic, Anopheles punctulatus and Anopheles koliensis, virtually disappeared from large areas where DDT was sprayed. However, high levels of transmission have been maintained by Anopheles farauti, which altered its behaviour to blood-feed early in the evening and outdoors and, thereby, avoiding exposure to the insecticides used in IRS. This example indicates that the efficacy of programmes relying on indoor vector control (IRS and long-lasting, insecticide-treated nets [LLINs]) will be significantly reduced if the vectors change their behaviour to avoid entering houses. Conclusions Behavioural resistance is less frequently seen compared with physiological resistance (where the mosquito contacts the insecticide but is not killed), but is potentially more challenging to control programmes because the intervention effectiveness cannot be restored by rotating the insecticide to one with a different mode of action. The scientific community needs to urgently develop systematic methods for monitoring behavioural resistance and then to work in collaboration with vector control programmes to implement monitoring in sentinel sites. In situations where behavioural resistance is detected, there will be a need to target other bionomic vulnerabilities that may exist in the larval stages, during mating, sugar feeding or another aspect of the life cycle of the vector to continue the drive towards elimination.

2013-01-01

91

Magnetotail Changes in Relation to the Solar Wind Magnetic Field and Magnetospheric Substorms  

Microsoft Academic Search

Substorm activity is known to be associated with changes in the solar wind parameters and the magnetotail configuration. In this paper we investigate whether the magnetotail changes occur only as a consequence of substorms or also as a direct consequence of changes in the solar wind paxameters. Using data from several satellites (Ogo 5, ATS 1, Imp 4, Explorer 33

MICHEL P. AUBRYAND; Robert L. McPherron

1971-01-01

92

STOL Tactical Aircraft Investigation. Volume IV. Analysis of Wind Tunnel Data: Vectored Thrust/Mechanical Flaps and Internally Blown Jet Flaps.  

National Technical Information Service (NTIS)

The report presents the analysis of 728 hours of testing, conducted in the Boeing V/STOL 20 x 20 ft. Wind Tunnel, on a model of a medium STOL transport with vectored thrust and jet flap powered-lift systems. The interactions between the two powered lift s...

J. L. Lee J. P. Palmer J. R. Monk

1973-01-01

93

Effectiveness of Changing Wind Turbine Cut-in Speed to Reduce Bat Fatalities at Wind Facilities  

Microsoft Academic Search

ACKNOWLEDGMENTS This study was conducted under the auspices ofthe Bats and Wind Energy Cooperative. We wish to thank the American Wind Energy Association (AWEA), Bat Conservation International (BCI), the National Renewable Energy Laboratory-Department of Energy (NREL), and the U.S. Fish and Wildlife Service (USFWS) for partnering to form the Bats and Wind Energy Cooperative (BWEC). Tom Gray (AWEA), Alex Hoar

Edward B. Arnett; Michael Schirmacher; Manuela M. P. Huso; John P. Hayes

94

Impacts of past and future climate change on wind energy resources in the United States  

NASA Astrophysics Data System (ADS)

The links between climate change and trends in wind energy resources have important potential implications for the wind energy industry, and have received significant attention in recent studies. We have conducted two studies that provide insights into the potential for climate change to affect future wind power production. In one experiment, we projected changes in power capacity for a hypothetical wind farm located near Kennewick, Washington, due to greenhouse gas-induced climate change, estimated using a set of regional climate model simulations. Our results show that the annual wind farm power capacity is projected to decrease 1.3% by 2050. In a wider study focusing on wind speed instead of power, we analyzed projected changes in wind speed from 14 different climate simulations that were performed in support of the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR4). Our results show that the predicted ensemble mean changes in annual mean wind speeds are expected to be modest. However, seasonal changes and changes predicted by individual models are large enough to affect the profitability of existing and future wind projects. The majority of the model simulations reveal that near-surface wind speed values are expected to shift poleward in response to the IPCC A2 emission scenario, particularly during the winter season. In the United States, most models agree that the mean annual wind speed values will increase in a region extending from the Great Lakes southward across the Midwest and into Texas. Decreased values, though, are predicted across most of the western United States. However, these predicted changes have a strong seasonal dependence, with wind speed increases over most of the United States during the winter and decreases over the northern United States during the summer.

McCaa, J. R.; Wood, A.; Eichelberger, S.; Westrick, K.

2009-12-01

95

Full scale experimental analysis of extreme coherent gust with wind direction changes (EOD)  

NASA Astrophysics Data System (ADS)

A coherent wind speed and wind direction change (ECD) load case is defined in the wind turbine standard. This load case is an essential extreme load case that e.g. may be design driving for flap defection of active stall controlled wind turbines. The present analysis identifies statistically the magnitudes of a joint gust event defined by a simultaneously wind speed- and direction change in order to obtain an indication of the validity of the magnitudes specified in the IEC code. The analysis relates to pre-specified recurrence periods and is based on full-scale wind field measurements. The wind speed gust amplitude, occurring simultaneously with a wind direction change, corresponds well to the recommended ECD value of 15 m/s, except for the complex terrain case, where estimated extreme wind speed gust amplitudes are seen to exceed the IEC value with approximately 50%. The estimated extreme wind direction gust amplitudes associated with the investigated European sites are low compared to the recommended IEC- values. However, these values, as function of the mean wind speed, are difficult to validate thoroughly due to the limited number of fully correlated measurements.

Hansen, K. S.; Larsen, G. C.

2007-07-01

96

Possible Impacts of Climate Change on Wind Gust under Downscaled Future Climate Conditions over Ontario, Canada  

NASA Astrophysics Data System (ADS)

The overarching purpose of this study was to project changes in the occurrence frequency and magnitude of future wind gust events under downscaled future climate conditions over Ontario, Canada. Wind gust factors were employed to simulate hourly/daily wind gust based on hourly/daily wind speed. Regression-based downscaling methods were used to downscale future hourly/daily wind speed to each of the 14 selected cities in Ontario for eight GCM models with IPCC SRES A2 and B1 scenarios. The wind gust simulation models were then applied using downscaled future GCM wind speed data to project changes in occurrence frequency and intensity of the future hourly/daily wind gust events. Downscaling transfer functions and wind gust simulation models were validated using a cross-validation scheme and comparing data distributions and extreme-event frequencies derived from downscaled GCM control runs and observations over a comparative time period 1961-2000. The results showed that the models for all variables used in the study performed well. By comparing the current-past averaged conditions, the occurrence frequency and intensity of future wind gust events in the study area are projected to increase. The modeled results from this study found that the frequency and intensity of future wind gust events are projected to significantly increase under a changing climate in this century. This talk will introduce the research project and outline the modeling exercise and verification process. The major findings on future wind gust projections from the study will be summarized in the presentation as well. One of the major conclusions from the study is that the procedures used in the study are useful for climate change impact analysis on future wind gusts. The implication of the significant increases in future wind gust risks would be useful to be considered when revising engineering infrastructure design standards and developing adaptation strategies and policies.

Shouquan Cheng, Chad; Li, Guilong

2010-05-01

97

Retinal degeneration progression changes lentiviral vector cell targeting in the retina.  

PubMed

In normal mice, the lentiviral vector (LV) is very efficient to target the RPE cells, but transduces retinal neurons well only during development. In the present study, the tropism of LV has been investigated in the degenerating retina of mice, knowing that the retina structure changes during degeneration. We postulated that the viral transduction would be increased by the alteration of the outer limiting membrane (OLM). Two different LV pseudotypes were tested using the VSVG and the Mokola envelopes, as well as two animal models of retinal degeneration: light-damaged Balb-C and Rhodopsin knockout (Rho-/-) mice. After light damage, the OLM is altered and no significant increase of the number of transduced photoreceptors can be obtained with a LV-VSVG-Rhop-GFP vector. In the Rho-/- mice, an alteration of the OLM was also observed, but the possibility of transducing photoreceptors was decreased, probably by ongoing gliosis. The use of a ubiquitous promoter allows better photoreceptor transduction, suggesting that photoreceptor-specific promoter activity changes during late stages of photoreceptor degeneration. However, the number of targeted photoreceptors remains low. In contrast, LV pseudotyped with the Mokola envelope allows a wide dispersion of the vector into the retina (corresponding to the injection bleb) with preferential targeting of Müller cells, a situation which does not occur in the wild-type retina. Mokola-pseudotyped lentiviral vectors may serve to engineer these glial cells to deliver secreted therapeutic factors to a diseased area of the retina. PMID:21901134

Calame, Maritza; Cachafeiro, Maité; Philippe, Stéphanie; Schouwey, Karine; Tekaya, Meriem; Wanner, Dana; Sarkis, Chamsy; Kostic, Corinne; Arsenijevic, Yvan

2011-08-25

98

Things Fall Apart: Topology Change From Winding Tachyons  

SciTech Connect

We argue that closed string tachyons drive two spacetime topology changing transitions--loss of genus in a Riemann surface and separation of a Riemann surface into two components. The tachyons of interest are localized versions of Scherk-Schwarz winding string tachyons arising on Riemann surfaces in regions of moduli space where string-scale tubes develop. Spacetime and world-sheet renormalization group analyses provide strong evidence that the decay of these tachyons removes a portion of the spacetime, splitting the tube into two pieces. We address the fate of the gauge fields and charges lost in the process, generalize it to situations with weak flux backgrounds, and use this process to study the type 0 tachyon, providing further evidence that its decay drives the theory sub-critical. Finally, we discuss the time-dependent dynamics of this topology-changing transition and find that it can occur more efficiently than analogous transitions on extended supersymmetric moduli spaces, which are limited by moduli trapping.

Adams, A.

2005-02-04

99

Sharp changes of solar wind density as a possible sign of magnetic reconnection at current sheets  

Microsoft Academic Search

Sharp changes of solar wind plasma density (or sharp changes of ion flux -SCIFs) were initially observed near the Earth by Interball-1 spacecraft and then confirmed through analyses of WIND SWE data. Abrupt density increases and decreases (in several times per several minutes or even seconds) happen, on the average, several times per day, and they are not associated with

Olga Khabarova; Georgy Zastenker

2010-01-01

100

Wind  

NSDL National Science Digital Library

This document examine wind power as an energy resource. The reading will define wind and discuss topics such as (1) The history of wind machines, (2) Today's windmills, and (3) Types of wind machines. This resource is structured as an informational handout to supplement your energy activities or to generate discussion questions. Copyright 2005 International Technology Education Association

National Energy Education Development (NEED) Project

2003-01-01

101

Regional and seasonal response of a West Nile virus vector to climate change.  

PubMed

Climate change will affect the abundance and seasonality of West Nile virus (WNV) vectors, altering the risk of virus transmission to humans. Using downscaled general circulation model output, we calculate a WNV vector's response to climate change across the southern United States using process-based modeling. In the eastern United States, Culex quinquefasciatus response to projected climate change displays a latitudinal and elevational gradient. Projected summer population depressions as a result of increased immature mortality and habitat drying are most severe in the south and almost absent further north; extended spring and fall survival is ubiquitous. Much of California also exhibits a bimodal pattern. Projected onset of mosquito season is delayed in the southwestern United States because of extremely dry and hot spring and summers; however, increased temperature and late summer and fall rains extend the mosquito season. These results are unique in being a broad-scale calculation of the projected impacts of climate change on a WNV vector. The results show that, despite projected widespread future warming, the future seasonal response of C. quinquefasciatus populations across the southern United States will not be homogeneous, and will depend on specific combinations of local and regional conditions. PMID:24019459

Morin, Cory W; Comrie, Andrew C

2013-09-09

102

The Ocean's Abyssal Mass Flux Sustained Primarily By the Wind: Vector Correlation of Time Series in Upper and Abyssal Layers  

NASA Astrophysics Data System (ADS)

As Wunsch has recently noted (2002), use of the term "thermohaline circulation" is muddled. The term is used with at least seven inconsistent meanings, among them abyssal circulation, the circulation driven by density and pressure differences in the deep ocean, the global conveyor, and at least four others. The use of a single term for all these concepts can create an impression that an understanding exists whereby in various combinations the seven meanings have been demonstrated to mean the same thing. But that is not the case. A particularly important consequence of the muddle is the way in which abyssal circulation is sometimes taken to be driven mostly or entirely by temperature and density differences, and equivalent to the global conveyor. But in fact the distinction between abyssal and upper-layer circulation has not been measured. To find out whether available data justifies a distinction between the upper-layer and abyssal circulations, this study surveyed velocity time series obtained by deep current meter moorings. Altogether, 114 moorings were identified, drawn from about three dozen experiments worldwide over the period 1973-1996, each of which deployed current meters in both the upper (2003750) layers. For each pair of current meters, the Kundu and Crosby measures of vector correlation were estimated, as well as coherences for periods from 10 to 60 days. In the North Atlantic, for example, Kundu vector correlation (50-day window): 0.48 +/- .03 Crosby vector correlation (absolute value, 50 day window): 0.46 +/- .07 Coherence at 60 days: .36 +/- .07 - at 30 days: 0.40 +/- .06 - at 10 days: 0.22 +/- .05 Most figures for the South Atlantic, Pacific and Southern Oceans are similar. Those obtained in the Indian Ocean or near the Equator are somewhat different. The statistics obtained here are consistent with the work of Wunsch (1997), and tend to confirm Wunsch's result that current velocities at depth are linked with those in the upper layers. Energetics of the circulation that do not take this into account are making an unjustifiable approximation of the physics. These results do not tell us whether time averaged flow on longer time scales might permit distinction of upper layer and abyssal flow components. Some intriguing corollaries do follow. First, the abyssal circulation is not identically the same thing as a global conveyor belt driven by temperature and density differences. Rather, as Wunsch noted (2002), the ocean's mass flux is sustained primarily by the wind. We may add that these wind patterns are about as robust as the temperature differences between equator and pole; this major driver of circulation is not a frail phenomenon. Second, the classical notion of a level of no motion that is also a constant-density surface, an LNM, is inconsistent with the results presented here. Such an LNM would wall off the upper layer circulation from the lower, and as they are not walled off, there can be no such LNM. Third, wind stress is being transmitted down column, presumably to the sea floor.

Hancock, L. O.

2003-12-01

103

Community-based dengue vector control: experiences in behavior change in Metropolitan Manila, Philippines.  

PubMed

Dengue is the most important mosquito-borne disease in the Philippines, especially in Metropolitan Manila where communities are socially and economically diverse, and city governments struggle to provide basic services such as continuously available, piped water supply to residents. We examined responses to introducing water container management to control dengue vectors in two diverse communities in Masagana City: Village A (gated community) and Village B (informal settlers community). The roll out of the intervention was carried out by the study team, dengue control personnel and local health workers (BHWs). A behavioural change framework was used to describe the community responses to the introduction of a new vector control intervention - household water container management. Although, the desired outcome was not achieved during the study's timeline, observation on processes of behaviour change underscored the importance of understanding the social nature of the urban communities, often overlooked structures when dengue control program and researchers introduce new dengue control interventions. PMID:23318237

Espino, Fe; Marco, Jesusa; Salazar, Nelia P; Salazar, Ferdinand; Mendoza, Ysadora; Velazco, Aldwin

2012-12-01

104

Recent tax law changes create new opportunities for leasing wind energy property  

SciTech Connect

Recent changes in tax law make leveraged lease transactions far more attractive on paper than they were before the changes. However, changes in the economy and the financial industry and other changes in law counterbalance the favorable tax law changes and make it uncertain whether lease transactions will be used to finance new wind facilities. (author)

Schutzer, George J.

2010-01-15

105

Changing photospheric vector magnetic fields associated with a B4.2-class solar flare  

NASA Astrophysics Data System (ADS)

Recent observations have provided evidence that the solar photospheric magnetic fields could have rapid and permanent changes in both longitudinal and transverse components associated with large (X- or M-class) solar flares. However, few observations have been reported about small flares. In this paper we find the observational evidence of changing photospheric vector magnetic fields associated with a B4.2-class flare obtained with the Solar Magnetic Field Telescope (SMFT) installed at Huairou Solar Observing Station (HSOS) of Nation Astronomical Observatories of Chinese Academy of Sciences.

Su, Jiangtao; Liu, Yu; Shen, Yuandeng

2013-07-01

106

Land cover change detection with change vector in the red and near-infrared reflectance space  

Microsoft Academic Search

An enhanced land cover change indicator product is produced using the two 250-m spatial resolution bands of the moderate resolution spectroradiometer (MODIS) of the NASA Earth Observing System. The rationale for creating the 250-m resolution land cover change product is that a very high proportion of land cover changes occur at the finest MODIS spatial resolutions. Multiple change detection algorithms

X. Zhan; C. Huang; J. Townshend; R. DeFries; M. Hansen; C. Dimiceli; R. Sohlberg; J. Hewson-Scardelletti; A. Tompkins

1998-01-01

107

Quantifying changes in the bone microarchitecture using Minkowski-functionals and scaling vectors: a comparative study  

NASA Astrophysics Data System (ADS)

Osteoporosis is a metabolic bone disease leading to de-mineralization and increased risk of fracture. The two major factors that determine the biomechanical competence of bone are the degree of mineralization and the micro-architectural integrity. Today, modern imaging modalities exist that allow to depict structural details of trabecular bone tissue. Recently, non-linear techniques in 2D and 3D based on the scaling vector method (SVM) and the Minkowski functionals (MF) have been introduced, which show excellent performance in predicting bone strength and fracture risk. However, little is known about the performance of the various parameters with respect to monitoring structural changes due to progression of osteoporosis or as a result of medical treatment. We test and compare the two methodologies using realistic two-dimensional simulations of bone structures, which model the effect of osteoblasts and osteoclasts on the local change of relative bone density. Different realizations with slightly varying control parameters are considered. Our results show that even small changes in the trabecular structures, which are induced by variation of a control parameter of the system, become discernible by applying both the MF and the locally adapted scaling vector method. The results obtained with SVM are superior to those obtained with the Minkowski functionals. An additive combination of both measures drastically increases the sensitivity to slight changes in bone structures. These findings may be especially important for monitoring the treatment of patients, where the early recognition of (drug-induced) changes in the trabecular structure is crucial.

Raeth, Christoph W.; Mueller, Dirk; Link, Thomas M.; Boehm, Holger; Monetti, Roberto

2006-03-01

108

Design of a bistatic dual-Doppler radar for retrieving vector winds using one transmitter and a remote low-gain passive receiver  

Microsoft Academic Search

A bistatic dual-Doppler network consisting of an existing single transmitting pencil-beam weather radar and a remotely located, nontransmitting, passive bistatic receiver with a low-gain antenna was constructed and tested during 1993. High-quality dual Doppler vector winds were retrieved from this system. The windfields were compared with those collected with a traditional two-transmitter dual-Doppler system. Several interesting engineering challenges relating to

JOSHUA WURMAN; MITCH RANDALL; CHARLES L. FRUSH; ERIC LOEW; CHRISTOPHER L. HOLLOWAY

1994-01-01

109

Wind-stress feedback amplification of abrupt millennial-scale climate changes  

NASA Astrophysics Data System (ADS)

The influence of changes in surface wind-stress on the properties (amplitude and period) and domain of existence of thermohaline millennial oscillations is studied by means of a coupled model of intermediate complexity set up in an idealized spherical sector geometry of the Atlantic basin. Using the atmospheric CO2 concentration as the control parameter, bifurcation diagrams of the model are built to show that the influence of wind-stress changes on glacial abrupt variability is threefold. First, millennial-scale oscillations are significantly amplified through wind-feedback-induced changes in both northern sea ice export and oceanic heat transport. Changes in surface wind-stress more than double the amplitude of the strong warming events that punctuate glacial abrupt variability obtained under prescribed winds in the model. Second, the average duration of both stadials and interstadials is significantly lengthened and the temporal structure of observed variability is better captured under interactive winds. Third, the generation of millennial-scale oscillations is shown to occur for significantly colder climates when wind-stress feedback is enabled. This behaviour results from the strengthening of the negative temperature-advection feedback associated with stronger northward oceanic heat transport under interactive winds.

Arzel, Olivier; England, Matthew H.

2013-02-01

110

The role of changes in the seasonality in strong wind season shortening over China  

NASA Astrophysics Data System (ADS)

Previous studies have shown that long term temperature change is not only reflected in the annual means of temperature records but also in the changes in seasonality (seasonal cycle), especially in the extra tropical regions. Since surface wind speed is also an important index for describing climate change, the change in seasonality of wind speed raise interest in recent years. In this study, the seasonality and long term trends in seasonal cycles in China are analyzed, based on the dataset of daily surface wind speed records at 600 weather stations during the period 1970-2005. The seasonality here is referred to as a refined modulated annual cycle (MAC). Several methods are used for describing the physical features of seasonality. The Ensemble Empirical Mode Decomposition (EEMD) is applied to extract modulated annual cycle (MAC) of surface wind speed, and the Mann-Kendall test is used for the assessment of long term trend in seasonality. The results show that strong wind season in selected stations has arrived significantly earlier by 2-3 days (/10 years) in the past 40 years along with prominently late ending by 1-3 days (/10 years), which is mostly due to phase changes in the seasonality and low frequency variability. Furthermore, the peak value of strong wind season has weakened in the past 40 years by 10%-20%, which is due to the amplitude changes in the seasonality. Variations in the MAC component explain over 90% of the total variance in the surface wind speed records.

Feng, T.; Fu, Z. T.

2012-04-01

111

Analyses of climate change impacts on wind speed and energy potential by using ANN  

NASA Astrophysics Data System (ADS)

The main objectives of this study are; i) to define variations of wind velocity and energy potential in Istanbul and Isparta, ii) to study trends, cyclic components, micro, meso and macro scale effects and climate changing, iii) to predict wind energy potential by using artificial neural networks (ANN). Wavelet methodologies present better results on temporal and spatial data analyses. Results of this paper evaluate wind energy potential, its annual and inter-annual variability, self similarity; and relation with periodic and non-periodic fluctuations of wind speed values in two study areas.

Aslan, Zafer; Erdemir, Gökhan; Tokgozlu, Ahmet

2012-07-01

112

Change-vector analysis in multitemporal space: A tool to detect and categorize land-cover change processes using high temporal-resolution satellite data  

Microsoft Academic Search

Analysis of change vectors in the multitemporal space, applied to multitemporal local area coverage imagery obtained by the Advanced Very-High Resolution Radiometer on NOAA-9 and NOAA-11 orbiting platforms, clearly reveals the nature and magnitude of land-cover change in a region of West Africa. The change vector compares the difference in the time-trajectory of a biophysical indicator, such as the normalized

E. F. Lambin; A. H. Strahler

1994-01-01

113

Detecting land-use/land-cover change in rural-urban fringe areas using extended change-vector analysis  

NASA Astrophysics Data System (ADS)

Detecting land-use/land-cover (LULC) changes in rural-urban fringe areas (RUFAs) timely and accurately using satellite imagery is essential for land-use planning and management in China. Although traditional spectral-based change-vector analysis (CVA) can effectively detect LULC change in many cases, it encounters difficulties in RUFAs because of deficiencies in the spectral information of satellite images. To detect LULC changes in RUFAs effectively, this paper proposes an extended CVA approach that incorporates textural change information into the traditional spectral-based CVA. The extended CVA was applied to three different pilot RUFAs in China with different remotely sensed data, including Landsat Thematic Mapper (TM), China-Brazil Earth Resources Satellite (CBERS) and Advanced Land Observing Satellite (ALOS) images. The results demonstrated the improvement of the extended CVA compared to the traditional spectral-based CVA with the overall accuracy increased between 4.66% and 8.00% and the kappa coefficient increased between 0.10 and 0.15, respectively. The advantage of the extended CVA lies in its integration of both spectral and textural change information to detect LULC changes, allowing for effective discrimination of LULC changes that are spectrally similar but texturally different in RUFAs. The extended CVA has great potential to be widely used for LULC-change detection in RUFAs, which are often heterogeneous and fragmental in nature, with rich textural information.

He, Chunyang; Wei, Anni; Shi, Peijun; Zhang, Qiaofeng; Zhao, Yuanyuan

2011-08-01

114

Changes in the Burgers Vector of Perfect Dislocation Loops without Contact with the External Dislocations  

SciTech Connect

We report the observations of a new type of changing process in the Burgers vector of dislocations by in situ transmission electron microscopy. Small interstitial-type perfect dislocation loops in bcc iron with diameters less than approximately 50 nm are transformed from a 1/2<111> loop to another 1/2<111> one or an energetically unfavorable <100> one; furthermore, a <100> loop is transformed to a 1/2<111> one. These transformations occurred on high-energy electron irradiation or simple heating without contact with external dislocations. The origin of these phenomena is discussed.

Arakawa, K.; Hatanaka, M.; Mori, H. [Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, 7-1, Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Kuramoto, E. [Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan); Ono, K. [Department of Material Science, Shimane University, 1060 Nishikawatsu, Matsue 690-8504 (Japan)

2006-03-31

115

Malaria vectors in the changing environment of the southern Punjab, Pakistan.  

PubMed

The Pakistani Punjab experienced several devastating malaria epidemics during the twentieth century. Since the 1980s, however, malaria has been at a low ebb, while in other areas of Pakistan and neighbouring India malaria is on the increase. This raises the question of whether transmission in the Pakistani Punjab may have been influenced by a change in vector species abundance or composition, possibly induced by environmental changes. To investigate this question, routinely-collected government entomological data for the period 1970 to 1999 for the district of Bahawalnagar, in the Indus Basin irrigation system in the southern Punjab, was analysed. Our findings suggest that Anopheles stephensi has increased in prevalence and became more common than A. culicifacies during the 1980s. This shift in species dominance may be due to the large-scale ecological changes that have taken place in the Punjab, where irrigation-induced waterlogging of soil with related salinization has created an environment favourable for the more salt-tolerant A. stephensi. Some biotypes of A. stephensi are suspected of being less efficient vectors and, therefore, the shift in species dominance might have played a role in the reduced transmission in the Punjab, although further research is needed to investigate the effect of other transmission-influencing factors. PMID:15138083

Klinkenberg, Eveline; Konradsen, Flemming; Herrel, Nathaly; Mukhtar, Muhammad; van der Hoek, Wim; Amerasinghe, Felix P

2004-07-01

116

Sharp solar wind density changes and their connection with heliospheric current sheet  

Microsoft Academic Search

Poor-investigated sharp changes of solar wind plasma density (its increases and decreases in several times during several minutes or even seconds), simultaneously observed by Interball-1 and Wind spacecraft near the Earth, on the average, several times per day, are considered. Firstly they had been found due to analysis of Interball-1 one-second plasma data and were called as SCIFs (sharp changes

O. V. Khabarova; G. N. Zastenker

2009-01-01

117

Changes in wind speed and extremes in Beijing during 1960-2008 based on homogenized observations  

NASA Astrophysics Data System (ADS)

Daily observations of wind speed at 12 stations in the Greater Beijing Area during 1960-2008 were homogenized using the Multiple Analysis of Series for Homogenization method. The linear trends in the regional mean annual and seasonal (winter, spring, summer and autumn) wind speed series were -0.26, -0.39, -0.30, -0.12 and -0.22 m s-1 (10 yr)-1, respectively. Winter showed the greatest magnitude in declining wind speed, followed by spring, autumn and summer. The annual and seasonal frequencies of wind speed extremes (days) also decreased, more prominently for winter than for the other seasons. The declining trends in wind speed and extremes were formed mainly by some rapid declines during the 1970s and 1980s. The maximum declining trend in wind speed occurred at Chaoyang (CY), a station within the central business district (CBD) of Beijing with the highest level of urbanization. The declining trends were in general smaller in magnitude away from the city center, except for the winter case in which the maximum declining trend shifted northeastward to rural Miyun (MY). The influence of urbanization on the annual wind speed was estimated to be about -0.05 m s-1 (10 yr)-1 during 1960-2008, accounting for around one fifth of the regional mean declining trend. The annual and seasonal geostrophic wind speeds around Beijing, based on daily mean sea level pressure (MSLP) from the ERA-40 reanalysis dataset, also exhibited decreasing trends, coincident with the results from site observations. A comparative analysis of the MSLP fields between 1966-1975 and 1992-2001 suggested that the influences of both the winter and summer monsoons on Beijing were weaker in the more recent of the two decades. It is suggested that the bulk of wind in Beijing is influenced considerably by urbanization, while changes in strong winds or wind speed extremes are prone to large-scale climate change in the region.

Li, Zhen; Yan, Zhongwei; Tu, Kai; Liu, Weidong; Wang, Yingchun

2011-03-01

118

Foehn Winds in the McMurdo Dry Valleys, Antarctica: A Driver of Environmental Change?  

NASA Astrophysics Data System (ADS)

Foehn winds are warm, dry and gusty winds that commonly occur in many mid-latitude mountainous regions. Detailed investigations into foehn winds in polar regions and their effects on landscape processes however, are rare. Foehn events are frequently experienced in the McMurdo Dry Valleys, Antarctica where they are caused by topographic modification of strong southwesterly airflow that is forced by synoptic-scale cyclones in the Amundsen/Ross Sea region. Recent research has shown that the intra and interannual frequency and intensity of foehn events varies in response to the position and frequency of these synoptic cyclones. The El Niño Southern Oscillation and the Southern Annular Mode are known sources of circulation anomalies in this region, and the frequency of foehn winds in the McMurdo Dry Valleys has been linked to these sources of climate variability. Despite the high frequency of foehn events in the McMurdo Dry Valleys, the influence of foehn winds on landscape processes of this polar desert is not well understood. Here we present research that integrates numerical weather model products, automatic weather station observations, stream discharge data and remote sensing techniques to quantify the influence of foehn winds on environmental processes in the McMurdo Dry Valleys. During summer, foehn winds play a critical role in raising air and soil temperatures above 0°C. Sublimation, meltwater generation and snow persistence are also shown to be significantly influenced by foehn winds and their affects on landscape processes which persist for several days after foehn wind cessation. Foehn winds play a large role in keeping the valleys snow and ice free. Any precipitation that does fall is quickly evaporated/sublimated by foehn winds. We conclude that foehn winds in the McMurdo Dry Valleys are the major cause of contemporary landscape change and aridity.

Speirs, J. C.; McGowan, H. A.

2011-12-01

119

Potential impacts of climate change on the ecology of dengue and its mosquito vector the Asian tiger mosquito (Aedes albopictus)  

Microsoft Academic Search

Shifts in temperature and precipitation patterns caused by global climate change may have profound impacts on the ecology of certain infectious diseases. We examine the potential impacts of climate change on the transmission and maintenance dynamics of dengue, a resurging mosquito-vectored infectious disease. In particular, we project changes in dengue season length for three cities: Atlanta, GA; Chicago, IL and

R A Erickson; K Hayhoe; S M Presley; L J S Allen; K R Long; S B Cox

2012-01-01

120

Analyses of possible changes in intense and extreme wind speeds over northern Europe under climate change scenarios  

Microsoft Academic Search

Dynamical downscaling of ECHAM5 using HIRHAM5 and RCA3 for a northern European domain focused on Scandinavia indicates sustained\\u000a extreme wind speeds with long recurrence intervals (50 years) and intense winds are not likely to evolve out of the historical\\u000a envelope of variability until the end of C21st. Even then, significant changes are indicated only in the SW of the domain\\u000a and

S. C. PryorR; R. J. Barthelmie; N. E. Clausen; M. Drews; N. MacKellar; E. Kjellström

2010-01-01

121

Preliminary Assessment of Climate Change Impacts on the UK Onshore Wind Energy Resource  

Microsoft Academic Search

Wind power is currently the fastest growing renewable technology and will play a significant role in constraining the extent of climate change. However, the very fact that its ‘fuel source’ is driven by the climate may leave it exposed as climate changes over the coming decades. In this preliminary assessment, the potential for changes in climate to affect the significant

Gareth P. Harrison; Lucy C. Cradden; John P. Chick

2008-01-01

122

Widespread land surface wind decline in the Northern Hemisphere partly attributed to land surface changes  

NASA Astrophysics Data System (ADS)

The decline of surface wind observed in many regions of the world is a potential source of concern for wind power electricity generation. It is also suggested as the main cause of decreasing pan evaporation. In China, a persistent and significant decrease of monsoon winds was observed in all seasons. Surface wind declines were also evidenced in several regions of the world (U.S., Australia, several European countries). Except over China, no clear explanation was given for the wind decrease in the regions studied. Whether surface winds decrease is due to changes in the global atmospheric circulation or its variability, in surface processes or to observational trends has therefore not been elucidated. The identification of the drivers of such a decline requires a global investigation of available surface and upper-air wind data, which has not been conducted so far. Here we use global datasets of in-situ wind measurements that contain surface weather stations wind data (hourly or three-hourly data acquisition time step) and rawinsonde vertical wind data profiles (monthly time step) prepared by the NCAR. A set of 822 worldwide surface stations with continuous wind records was selected after a careful elimination of stations with obvious breaks and large gaps. This dataset mostly covers the Northern mid latitudes over the period 1979-2008. Using this data set, we found that annual mean wind speeds have declined at 73% of the surface stations over the past 30 years. In the Northern Hemisphere, positive wind trends are found only in a few places. In Europe, Central Asia, Eastern Asia and in North America the annual mean surface wind speed has decreased on average at a rate of -2.9, -5.9, -4.2, and -1.8 %/decade respectively, i.e. a decrease of about 10% in 30 years and up to about 20% in Central Asia. These results are robust to changes in the station selection method and parameters. By contrast, upper-air winds observed from rawinsondes, geostrophic winds deduced from pressure gradients, and modeled winds from weather re-analyses do not exhibit any comparable stilling trends than at surface stations. For instance, large-scale circulation changes captured in the most recent European Centre for Medium Range Weather Forecast re-analysis (ERA-interim) can only explain only up to 10-50% of the wind stilling, depending on the region. In addition, a significant amount of the slow-down could originate from a generalized increase in surface roughness, due for instance to forest growth and expansion, and urbanization. This hypothesis, which could explain up to 60% of the decline, is supported by remote sensing observations and theoretical calculations combined with meso-scale model simulations. For future wind power energy resource, the part of wind decline due to land cover changes is easier to cope with than that due to global atmospheric circulation slow down.

Thepaut, J.; Vautard, R.; Cattiaux, J.; Yiou, P.; Ciais, P.

2010-12-01

123

Changing the view of wind power development: More than “bricolage”  

Microsoft Academic Search

Understanding innovation depends at root on good qualitative descriptions. This paper re-assesses the role of “bricolage”, and the extent of science-based R&D and experience-based learning, in the development of the Danish wind turbine system. It argues that the competition between these two opposed frames of reference was never conclusively settled, but involved a reassertion of science-based R&D, which was ultimately

Chris Hendry; Paul Harborne

2011-01-01

124

Limited change in dune mobility in response to a large decrease in wind power in semi-arid northern China since the 1970s  

USGS Publications Warehouse

The climatic controls on dune mobility, especially the relative importance of wind strength, remain incompletely understood. This is a key research problem in semi-arid northern China, both for interpreting past dune activity as evidence of paleoclimate and for predicting future environmental change. Potential eolian sand transport, which is approximately proportional to wind power above the threshold for sand entrainment, has decreased across much of northern China since the 1970s. Over the same period, effective moisture (ratio of precipitation to potential evapotranspiration) has not changed significantly. This "natural experiment" provides insight on the relative importance of wind power as a control on dune mobility in three dunefields of northern China (Mu Us, Otindag, and Horqin), although poorly understood and potentially large effects of human land use complicate interpretation. Dune forms in these three regions are consistent with sand transport vectors inferred from weather station data, suggesting that wind directions have remained stable and the stations adequately represent winds that shaped the dunes. The predicted effect of weaker winds since the 1970s would be dune stabilization, with lower sand transport rates allowing vegetation cover to expand. Large portions of all three dunefields remained stabilized by vegetation in the 1970s despite high wind power. Since the 1970s, trends in remotely sensed vegetation greenness and change in mobile dune area inferred from sequential Landsat images do indicate widespread dune stabilization in the eastern Mu Us region. On the other hand, expansion of active dunes took place farther west in the Mu Us dunefield and especially in the central Otindag dunefield, with little overall change in two parts of the Horqin dunes. Better ground truth is needed to validate the remote sensing analyses, but results presented here place limits on the relative importance of wind strength as a control on dune mobility in the study areas. High wind power alone does not completely destabilize these dunes. A large decrease in wind power either has little short-term effect on the dunes, or more likely its effect is sufficiently small that it is obscured by human impacts on dune stability in many parts of the study areas. ?? 2008 Elsevier B.V. All rights reserved.

Mason, J. A.; Swinehart, J. B.; Lu, H.; Miao, X.; Cha, P.; Zhou, Y.

2008-01-01

125

Analyses of possible changes in intense and extreme wind speeds over northern Europe under climate change scenarios  

NASA Astrophysics Data System (ADS)

Dynamical downscaling of ECHAM5 using HIRHAM5 and RCA3 for a northern European domain focused on Scandinavia indicates sustained extreme wind speeds with long recurrence intervals (50 years) and intense winds are not likely to evolve out of the historical envelope of variability until the end of C21st. Even then, significant changes are indicated only in the SW of the domain and across the central Baltic Sea where there is some evidence for relatively small magnitude increases in the 50 year return period wind speed (of up to 15%). There are marked differences in results based on the two Regional Climate Models. Additionally, internal (inherent) variability and initial conditions exert a strong impact on projected wind climates throughout the twenty-first century. Simulations of wind gusts by one of the RCMs (RCA3) indicate some evidence for increased magnitudes (of up to +10%) in the southwest of the domain and across the central Baltic Sea by the end of the current century. As in prior downscaling of ECHAM4, dynamical downscaling of ECHAM5 indicates a tendency towards increased energy density and thus wind power generation potential over the course of the C21st. However, caution should be used in interpreting this inference given the high degree of wind climate projection spread that derives from the specific AOGCM and RCM used in the downscaling.

Pryor, S. C.; Barthelmie, R. J.; Clausen, N. E.; Drews, M.; MacKellar, N.; Kjellström, E.

2012-01-01

126

Southern Hemisphere westerly wind changes during the Last Glacial Maximum: model-data comparison  

NASA Astrophysics Data System (ADS)

The Southern Hemisphere (SH) westerly winds are thought to be critical to global ocean circulation, productivity, and carbon storage. For example, an equatorward shift in the winds, though its affect on the Southern Ocean circulation, has been suggested as the leading cause for the reduction in atmospheric CO2 during the Last Glacial period. Despite the importance of the winds, it is currently not clear, from observations or model results, how they behave during the Last Glacial. Here, an atmospheric modelling study is performed to help determine likely changes in the SH westerly winds during the Last Glacial Maximum (LGM). Using LGM boundary conditions, the maximum in SH westerlies is strengthened by ˜+1 m s-1 and moved southward by ˜2° at the 850 hPa pressure level. Boundary layer stabilisation effects over equatorward extended LGM sea-ice can lead to a small apparent equatorward shift in the wind band at the surface. Further sensitivity analysis with individual boundary condition changes indicate that changes in sea surface temperatures are the strongest factor behind the wind change. The HadAM3 atmospheric simulations, along with published PMIP2 coupled climate model simulations, are then assessed against the newly synthesised database of moisture observations for the LGM. Although the moisture data is the most commonly cited evidence in support of a large equatorward shift in the SH winds during the LGM, none of the models that produce realistic LGM precipitation changes show such a large equatorward shift. In fact, the model which best simulates the moisture proxy data is the HadAM3 LGM simulation which shows a small poleward wind shift. While we cannot prove here that a large equatorward shift would not be able to reproduce the moisture data as well, we show that the moisture proxies do not provide an observational evidence base for it.

Sime, Louise C.; Kohfeld, Karen E.; Le Quéré, Corinne; Wolff, Eric W.; de Boer, Agatha M.; Graham, Robert M.; Bopp, Laurent

2013-03-01

127

Combining Climatic Projections and Dispersal Ability: A Method for Estimating the Responses of Sandfly Vector Species to Climate Change  

Microsoft Academic Search

BackgroundIn the Old World, sandfly species of the genus Phlebotomus are known vectors of Leishmania, Bartonella and several viruses. Recent sandfly catches and autochthonous cases of leishmaniasis hint on spreading tendencies of the vectors towards Central Europe. However, studies addressing potential future distribution of sandflies in the light of a changing European climate are missing.MethodologyHere, we modelled bioclimatic envelopes using

Dominik Fischer; Philipp Moeller; Stephanie M. Thomas; Torsten J. Naucke; Carl Beierkuhnlein

2011-01-01

128

Modeled response of the West Nile virus vector Culex quinquefasciatus to changing climate using the dynamic mosquito simulation model  

Microsoft Academic Search

Climate can strongly influence the population dynamics of disease vectors and is consequently a key component of disease ecology.\\u000a Future climate change and variability may alter the location and seasonality of many disease vectors, possibly increasing\\u000a the risk of disease transmission to humans. The mosquito species Culex quinquefasciatus is a concern across the southern United States because of its role

Cory W. Morin; Andrew C. Comrie

2010-01-01

129

Changes of wind waves in the North Atlantic over the last 30 years  

NASA Astrophysics Data System (ADS)

In order to evaluate long-term climatic changes in wind wave height, visual wave estimates available from the Comprehensive Ocean-Atmosphere Data Set (GOADS) were updated for the period from 1964 to 1993. Analysis of the accuracy of visual estimates shows that observations from merchant ships can be used for the study of climate changes in storminess. Climate changes obtained in significant wave height, computed on the basis of the voluntary observed data, are quite consistent with those shown by the instrumental records at OWS L, Seven Stones Light Vessel and NDBC buoys. The linear trends in significant wave height, as well as in the wind sea and swell heights, were computed for the entire North Atlantic. Significant wave height increases of 10-30 cm/decade over the whole of the North Atlantic, except for the western and central subtropics were found. Changes in the swell height are very consistent with those seen in significant wave height. Nevertheless, wind sea indicates strong upward tendencies only in the central mid-latitudinal North Atlantic and does not show any significant trends in the Northeast Atlantic, where instrumental records of Bacon and Carter report secular changes of about 1% a year. Wind waves of smaller occurrences show significantly negative changes in the Northeast Atlantic; that is in agreement with the wind sea periods changes. Possible mechanisms driving the swell changes with no pronounced increase of the sea height and wind velocity are discussed. Changes in the intensities of intramonthly variability in different synoptic ranges are considered as the major agent of the increasing swell. The conclusion is made that the upward swell changes are driven by the intensification of high frequency synoptic processes.

Gulev, Sergey K.; Hasse, Lutz

1999-08-01

130

Equatorial thermospheric wind changes during the solar cycle: Measurements at Arequipa, Peru, from 1983 to 1990  

Microsoft Academic Search

Fabry-Perot interferometer measurements of Doppler shifts in the nightglow 630-nm emission line have been used to determine near-equatorial thermospheric wind velocities at Arequipa, Peru, over â¼ 2\\/3 of a solar cycle. Monthly-average nocturnal variations in the meridional and zonal wind components were calculated from the nightly data to remove short term (day-to-day) variability, facilitating display of seasonal changes in the

M. A. Biondi; J. W. Jr. Meriwether; B.G. Fejer; S.A. Gonzalez; D. C. Hallenbeck

1991-01-01

131

Southern Hemisphere Westerly Wind Changes during the Last Glacial Maximum: Model-Data Comparison  

NASA Astrophysics Data System (ADS)

The Southern Hemisphere (SH) westerly winds are thought to be critical to both past and future global ocean circulation, productivity, and carbon storage. For example, an equatorward shift in the winds has been suggested as the leading cause for the reduction in atmospheric CO2 during the Last Glacial Maximum (LGM), through its affect on the Southern Ocean circulation. Despite the importance of the SH westerlies, paleo-records and modelling studies still disagree on how they behaved during the LGM. Here, a joint model-data evaluation study is performed to determine likely changes in the SH westerly winds during the LGM. HadAM3 atmospheric simulations, along with published PMIP2 coupled climate model simulations, are assessed against our newly synthesised database of moisture records for the LGM (Kohfeld et al., accepted, QSR). While moisture data are the most commonly cited evidence in support of a large equatorward shift in the SH winds during the LGM, none of the models that produce realistic LGM precipitation patterns show a large equatorward shift. In fact, the model which best simulates the moisture proxy data, our HadAM3 LGM simulation, shows a small poleward wind shift. Thus, moisture proxies do not provide a robust observational evidence base for equatorward shifted winds during the LGM (Sime et al, in press, QSR). Sensitivity simulations, featuring individual boundary condition changes, suggest that changes in sea surface temperatures are the strongest factor behind LGM wind changes, compared with sea ice and land ice effects. If the SH westerly winds were not shifted equatorward at the LGM, this raises intriguing questions regarding past and future carbon storage in the Southern Ocean.

Sime, Louise; Kohfeld, Karen; Le Quere, Corinne; Wolff, Eric; de Boer, Agatha; Graham, Robert; Bopp, Laurent

2013-04-01

132

Effect of change in large and fast solar wind dynamic pressure on geosynchronous magnetic field  

NASA Astrophysics Data System (ADS)

We present a comparison of changes in large and sharp solar wind dynamic pressure, observed by several spacecraft, with fast disturbances in the magnetospheric magnetic field, measured by the geosynchronous satellites. More than 260 changes in solar wind pressure during the period 1996-2003 are selected for this study. Large statistics show that an increase (a decrease) in dynamic pressure always results in an increase (a decrease) in the magnitude of geosynchronous magnetic field. The amplitude of response to the geomagnetic field strongly depends on the location of observer relative to the noon meridian, the value of pressure before disturbance, and the change in amplitude of pressure.

N, Borodkova L.; Liu, Jing-Bo; Huang, Zhao-Hui; G, Zastenker N.; Wang, Chi; P, Eiges E.

2006-10-01

133

Southern Hemisphere Westerly Wind Changes during the Last Glacial Maximum: Paleo-data Synthesis  

NASA Astrophysics Data System (ADS)

Changes in the strength and position of Southern Hemisphere westerly winds during the last glacial cycle have been invoked to explain glacial-interglacial climate fluctuations. However, neither paleo models nor paleodata agree on the magnitude, or even the sign, of the change in wind strength and latitude during the Last Glacial Maximum (LGM), compared to the recent past. This study synthesizes paleo-environmental data that have been used to infer changes in winds during the LGM compared with the late Holocene. These compilations include changes in terrestrial moisture, dust deposition, and ocean productivity, along with summaries of previously published information on sea surface temperatures (SSTs) and ocean dynamics in the Southern Hemisphere. Our compilations of terrestrial moisture from 94 sites and dust deposition from 87 sites show generally drier conditions for the LGM between 0 and 40°S, with wetter conditions along the west coasts and drying along the east coasts of continents. LGM dust deposition rates ranged from 2 to 4.5 times higher over the Southern Ocean and about 13 times higher over the Antarctic continent. For the oceans, reconstructed changes in SSTs show maximum cooling (>4°C) in the modern-day Subantarctic Zone, coincident with a region of enhanced export production during the LGM compared with today. We find that any hypothesis of LGM wind and climate change needs to provide a plausible explanation for increased moisture on the west coast of continents, cooler temperatures and higher productivity in the Subantarctic Zone, and reductions in Agulhas leakage around southern Africa. Our comparison suggests that an overall strengthening, an equatorward displacement, or no change at all in winds could all be interpreted as consistent with observations. If a single cause related to the southern westerlies is sought for all the evidence presented, then an equatorward displacement or strengthening of the winds would be consistent with the largest proportion of the data evidence. However, other processes, such as weakening or poleward shifts in winds, a weakened hydrological cycle, extended sea-ice cover, and changed buoyancy fluxes, cannot be ruled out as potential explanations of observed changes in moisture, surface temperature, and productivity. We contend that resolving the position and strength of westerly winds during the LGM remains elusive based on data reconstructions alone. However, we believe that these data reconstructions of environmental conditions can be used in conjunction with model simulations to identify which processes best represent westerly wind conditions during the LGM.

Kohfeld, Karen; Graham, Robert; De Boer, Agatha; Sime, Louise; Wolff, Eric; Le Quéré, Corinne; Bopp, Laurent

2013-04-01

134

Changes of the prevailing trade winds over the islands of Hawaii and the North Pacific  

NASA Astrophysics Data System (ADS)

Changes in the frequency and intensity of the prevailing northeast and east trade winds from 1973-2009 are analyzed from four land stations in the Hawaiian Islands. A nonparametric robust trend analysis indicates a downward trend in northeast trade wind frequency since 1973. At the Honolulu International Airport, northeast trade wind days usually occurred 291 days per year 37 years ago are observed to occur only 210 days per year in 2009. In contrast, the frequency of the east trade winds has increased over the past 37 years. Comparison of observations from four ocean buoys with land stations for the last 26 years (1984-2009) is presented. The northeast trade frequency is found to decrease for all eight stations while the east trade winds are found to increase in frequency. These results are similar to the longer (1973-2009) data set. Most buoys revealed an increase in trade wind speeds since 1984. The NCEP/NCAR reanalysis II data are used to analyze surface winds and sea level pressure (SLP) over the north Pacific. A northeast to east shifting of winds and an increase in SLP is found to occur from the 1980s to the 2000s epoch. Linear trends in reanalysis II from 1980 to 2009 indicated a strengthening of northeast trade winds over the Hawaiian Islands and in the subtropical eastern North Pacific with an extension of increased northerlies off the California coast. Meanwhile, southeast trades in the eastern North Pacific reduced their strength. Changes in trades in the western Pacific are relatively small.

Garza, Jessica A.; Chu, Pao-Shin; Norton, Chase W.; Schroeder, Thomas A.

2012-06-01

135

Power balancing in variable speed wind-energy systems using vector control of front-end converters  

Microsoft Academic Search

This paper presents a novel power balance control method for wind energy systems feeding an isolated grid. The system is based on a variable-speed wind energy conversion system (WECS) connected to an AC load using a power converter. An energy storage system, connected to the AC load using an additional converter, is used to balance the power generated by the

Roberto Cárdenas; Rubén Peña; Marcelo Pérez; Fernando Vargas; Greg Asher; Jon Clare

2005-01-01

136

The climate influence of anthropogenic land-use changes on near-surface wind energy potential in China  

Microsoft Academic Search

There is considerable interest in the potential impact of climate change on wind energy in China. The climate change of near-surface\\u000a wind energy potential in China under the background of global warming and its association with anthropogenic land-use changes\\u000a are investigated by calculating the difference in surface wind speeds between the NCEP\\/NCAR reanalysis data and the observations\\u000a since the re-analysis

Yan Li; Yuan Wang; HuiYun Chu; JianPing Tang

2008-01-01

137

Climate change impact of wind energy availability in the Eastern Mediterranean using the regional climate model PRECIS  

Microsoft Academic Search

Global near-surface wind fields are projected to change as a result of climate change. An enhanced knowledge of the changes in wind energy availability in the twenty-first century is essential for improving the development of wind energy production. We use the PRECIS regional model over the East Mediterranean to dynamically downscale the results of the Had3CM Atmosphere-Ocean coupled Global Circulation

A. Bloom; V. Kotroni; K. Lagouvardos

2008-01-01

138

Impact of land use change on wind erosion and dust emission: scenarios from the central US  

NASA Astrophysics Data System (ADS)

There will be significant changes in land cover and land use throughout the central United States in the coming years, particularly due to changes in US rangeland/farm policy and an increasing exploitation of land-intensive sustainable energy sources. The purpose of this study is to investigate the potential of these land use and land cover changes to alter wind erosion and dust emission from these highly erodible lands. Two models were inter-calibrated and then applied to investigate the effects of these changes: the Wind Erosion Prediction System (WEPS) and the Wind Erosion MOdel (WEMO). WEPS was developed to evaluate the effects of different cropland management systems, whereas WEMO was designed to quantify differences in wind erosion in rangeland ecosystems. We find that conversion of rangelands, even when the soil surface was disturbed, are lower than those expected from conversion to any of the crop management systems evaluated. These results indicate that policy and economic forces that shape land use decision making can have impact on wind erosion and, importantly, emission of dust with local and regional consequences.

Tatarko, J.; Okin, G. S.; Herrick, J.; Li, J.

2010-12-01

139

Winds of Change: How Black Holes May Shape Galaxies  

NASA Astrophysics Data System (ADS)

New observations from NASA's Chandra X-ray Observatory provide evidence for powerful winds blowing away from the vicinity of a supermassive black hole in a nearby galaxy. This discovery indicates that "average" supermassive black holes may play an important role in the evolution of the galaxies in which they reside. For years, astronomers have known that a supermassive black hole grows in parallel with its host galaxy. And, it has long been suspected that material blown away from a black hole - as opposed to the fraction of material that falls into it -- alters the evolution of its host galaxy. A key question is whether such "black hole blowback" typically delivers enough power to have a significant impact. Powerful relativistic jets shot away from the biggest supermassive black holes in large, central galaxies in clusters like Perseus are seen to shape their host galaxies, but these are rare. What about less powerful, less focused galaxy-scale winds that should be much more common? "We're more interested here in seeing what an "average"-sized supermassive black hole can do to its galaxy, not the few, really big ones in the biggest galaxies," said Dan Evans of the Massachusetts Institute of Technology who presented these results at the High Energy Astrophysics Division of the American Astronomical Society meeting in Kona, Hawaii. Evans and his colleagues used Chandra for five days to observe NGC 1068, one of the nearest and brightest galaxies containing a rapidly growing supermassive black hole. This black hole is only about twice as massive as the one in the center of our Galaxy, which is considered to be a rather ordinary size. The X-ray images and spectra obtained using Chandra's High Energy Transmission Grating Spectrometer (HETGS) showed that a strong wind is being driven away from the center of NGC 1068 at a rate of about a million miles per hour. This wind is likely generated as surrounding gas is accelerated and heated as it swirls toward the black hole. A portion of the gas is pulled into the black hole, but some of it is blown away. High energy X-rays produced by the gas near the black hole heat the ouflowing gas, causing it to glow at lower X-ray energies. This Chandra study by Evans and his colleagues is much deeper than previous X-ray observations. It allowed them to make a high-definition map of the cone-shaped volume lit up by the black hole and its winds. By combining measurement of the velocity of the clouds with estimates of the density of the gas, Evans and his colleagues showed that each year several times the mass of the Sun is being deposited out to large distances, about 3,000 light years from the black hole. The wind may carry enough energy to heat the surrounding gas and suppress extra star formation. "We have shown that even these middle-of-the-road black holes can pack a punch," said Evans. "I think the upshot is that these black holes are anything but ordinary." Further Chandra HETGS studies of other nearby galaxies will examine the impact of other AGN outflows, leading to improvements in our understanding of the evolution of both galaxies and black holes. "In the future, our own Galaxy's black hole may undergo similar activity, helping to shut down the growth of new stars in the central region of the Milky Way," said Evans. These new results provide a key comparison to previous work performed at Georgia State University and the Catholic University of America with the Hubble Space Telescope's STIS instrument. NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass. More information, including images and other multimedia, can be found at: http://chandra.harvard.edu and http://chandra.nasa.gov

2010-03-01

140

Causes for decadal changes in wind speed on the North Hemispheric land surfaces  

NASA Astrophysics Data System (ADS)

Observations indicate a decline of land surface wind speed in the northern Hemisphere of about 0.3 m/s (roughly 10%) in the past 30 years. Such a stilling is sufficient to affect evaporation and climate feedback processes, but may also impact technical applications such as wind power. Here, we carry out extensive sensitivity experiments for the period 1870-2005 with an atmospheric global climate model and assess the role of changes in roughness length as well as the effects of climate forcings. Consistent with previous studies, results show that, depending on the region, an increase of the roughness length by a factor of 1.35 to 2.9 over the past 30 years would be required to reproduce the observed wind stilling. However, such an increase may not necessarily be realistic everywhere. Additional sensitivity experiments suggest that independently from roughness length changes, past changes in sea-surface temperature and aerosol emissions (atmosphere-only response) also decrease the land surface wind speed after about 1950, explaining up to 20% of the observed stilling. In particular, we find increasing aerosol emissions to generally reduce the surface wind speed after about 1950 in most of the northern hemisphere, by a maximum of 0.3 m/s in India. Results also show that the short-term effects of increased greenhouse gas concentrations is small in comparison to the role of aerosols.

Bichet, A.; Wild, M.; Folini, D.; Schär, C.

2012-04-01

141

Characteristic Study of Vector-controlled Direct-driven Permanent Magnet Synchronous Generator in Wind Power Generation  

Microsoft Academic Search

With the advance of power electronics, direct-driven permanent magnet synchronous generators have drawn increased interest to wind turbine manufacturers due to its advantages over other variable-speed wind turbines. This article studies permanent magnet synchronous generator characteristics under the general d-q control strategy in the rotor-flux-oriented frame so as to benefit the development of advanced permanent magnet synchronous generator control technology.

Shuhui Li; Timothy A. Haskew; Eduard Muljadi; Cristina Serrentino

2009-01-01

142

Supervised Change Detection in VHR Images Using Support Vector Machines and Contextual Information  

NASA Astrophysics Data System (ADS)

One of the recent challenges in environmental studies is how to include and exploit multitemporal information from multispectral very high resolution (VHR) images. This problem is also known as change detection (CD). Nowadays, many approaches, both supervised and unsupervised, are known and the selection of the method depends strongly on the application, the scope of the study and on available time. In the present research an accurate multiclass supervised method based on Support Vector Machines (SVM) for multitemporal remotely sensed image classification is proposed. SVM is a method issued from the statistical learning theory, known for its good generalization abilities and its performance when dealing with high dimensional spaces. Moreover, its sparse solution provides a final model depending only on a few patterns with an associated nonzero weights (support vectors), and resulting in an optimal regularized complexity. The final decision is obtained with a linear separation of data in an induced kernel feature space, corresponding to a nonlinear classification in the input space. When dealing with CD in VHR imagery, misclassified patterns are often caused by the high variance of the information at pixel level, caused by noise and by the influence of the high spatial resolution. Considering a precise coregistration, the variance at object level is high both in space and in time. The usefulness of adding such information is in smoothing, following an object based or a texture based criteria, the interclass variance and increasing the intraclass variance. By adding such information the classifier can better perform when predicting the class of pixels, because of the neighborhood information that was intrinsically extrapolated by the filtering. In the proposed approach, the behavior of mathematical morphology and morphological profiles obtained with different parameters are studied in a CD setting. The series of features are extracted both on the multispectral images and on the panchromatic images covering the scene at different time. Finally, the model is developed by directly applying multitemporal classification on the multitemporal image, looking for both stable and changed classes. Accurate multiclass CD with VHR optical imagery is a very powerful tool when analyzing city sprawl evolution and urbanization regimes, or when the resolution of the images allows a fine analysis of a multitemporal phenomenon (natural hazards, post catastrophe assessment, risk maps…). The real case study deals with a multitemporal image issued from two QuickBird scenes of the city of Zurich, Switzerland. This work is supported by the SNFS Project No. 200021-126505 "KernelCD".

Volpi, Michele; Kanevski, Mikhail

2010-05-01

143

Downscaling of precipitation for climate change scenarios: A support vector machine approach  

NASA Astrophysics Data System (ADS)

The Climate impact studies in hydrology often rely on climate change information at fine spatial resolution. However, general circulation models (GCMs), which are among the most advanced tools for estimating future climate change scenarios, operate on a coarse scale. Therefore the output from a GCM has to be downscaled to obtain the information relevant to hydrologic studies. In this paper, a support vector machine (SVM) approach is proposed for statistical downscaling of precipitation at monthly time scale. The effectiveness of this approach is illustrated through its application to meteorological sub-divisions (MSDs) in India. First, climate variables affecting spatio-temporal variation of precipitation at each MSD in India are identified. Following this, the data pertaining to the identified climate variables (predictors) at each MSD are classified using cluster analysis to form two groups, representing wet and dry seasons. For each MSD, SVM- based downscaling model (DM) is developed for season(s) with significant rainfall using principal components extracted from the predictors as input and the contemporaneous precipitation observed at the MSD as an output. The proposed DM is shown to be superior to conventional downscaling using multi-layer back-propagation artificial neural networks. Subsequently, the SVM-based DM is applied to future climate predictions from the second generation Coupled Global Climate Model (CGCM2) to obtain future projections of precipitation for the MSDs. The results are then analyzed to assess the impact of climate change on precipitation over India. It is shown that SVMs provide a promising alternative to conventional artificial neural networks for statistical downscaling, and are suitable for conducting climate impact studies.

Tripathi, Shivam; Srinivas, V. V.; Nanjundiah, Ravi S.

2006-11-01

144

Soil CO2 Emissions: Changes in effective diffusivity due to sustained winds  

NASA Astrophysics Data System (ADS)

Soils are the largest terrestrial source of CO2 to the atmosphere and a crucial component in the global carbon balance. Through soil profile and surface monitoring of CO2 concentrations and fluxes it has been shown that soil physical parameters such as moisture and structure can exert strong control over soil CO2 production, storage and emissions. Often, this control is a result of changes in the gas transport potential, or effective diffusivity, of the soil matrix. Variations in wind speeds near the soil surface can induce pressure fluctuations and changes in the structure of the boundary-layer which may lead to changes in effective diffusivity. Sustained winds have the potential to alter both the concentrations of gas in the soil as well as the fluxes of gas to and from the soil matrix. Gas emissions studies at air-water interfaces have demonstrated these effects, showing clear correlations between wind speed and pCO2 but similar research has not been conducted to examine the subsurface effects of wind across the soil-atmosphere interface. A clear understanding of these processes will be critical to understand how they affect flux monitoring strategies as well as to enhance the current understanding of soil CO2 production and emissions. Using fans to generate artificial winds between 3 and 30 km/h and solid state CO2 sensors we examine changes in soil profile CO2 concentrations both in lab conditions using artificial soils with no vegetation and in field conditions under sparse grass cover. Preliminary results show that in both laboratory and field experiments, soil CO2 concentrations are lowered by 10-80% within 20 minutes of the wind speed change. Furthermore, after the fans are shut off, CO2 concentrations recover quickly to their original state implying that there is little change in microbial CO2 production and that the observed CO2 depletion is a result of changes in effective diffusivity. Estimates of the change in effective diffusivity range between 2 and 10 times the original diffusivity of the medium and show a positive, exponential dependence on wind speed. Results from this study will be applicable to measurement and monitoring of soil respired CO2 and to enhancing the understanding of physical constraints on soil C cycling.

Nickerson, N.; Risk, D.

2007-12-01

145

Navigational Vectors  

NSDL National Science Digital Library

This is a high school instructional unit that features nine lessons relating to vectors. Students build understanding of vector properties as they learn airplane navigation. Problem-based learning activities include reading real-time weather maps, tracking airplanes flying in U.S. skies, calculating vector components, analyzing effects of wind velocity, and completing training segments similar to a private pilot certification program. Participants have access to help from experts at the Polaris Career Center. Comprehensive teacher guides, student guides, reference materials, and assessments are included. This resource was developed by the Center for Innovation in Science and Engineering Education (CIESE). Participation is cost-free; additional options are available for registered users.

146

Surveillance of vector-borne diseases in Germany: trends and challenges in the view of disease emergence and climate change.  

PubMed

The changing epidemiology of vector-borne diseases represents a growing threat to human health. Contemporary surveillance systems have to adapt to these changes. We describe temporal trends and geographic origins of vector-borne diseases in Germany with regard to strengths of existing disease surveillance and to areas marked for improvement. We focused on hantavirus infection (endemic in Germany), chikungunya fever (recently emerging in Europe) and dengue fever (imported from tropical regions), representing important subgroups of vector-borne infections. Routine surveillance data on demographics, origin of infection and the date of reporting were analysed. From 2001 through 2007, 3,005 symptomatic hantavirus infections, and 85 cases of chikungunya fever were reported, similarly 1,048 cases of dengue fever in 2002 through 2007. The geographic origin of hantavirus infection was reported for 95.5% of all cases (dengue virus, 98.4%; chikungunya virus, 100%). Hantavirus infections were acquired in Germany in 97.6% of cases (n = 2800). In 2007, there was a marked increase of hantavirus cases, mainly in areas known to be endemic for hantavirus. In 2006, imported cases of chikungunya fever primarily returned from several islands of the Indian Ocean, while the majority of imported cases in 2007 came from India. The reported number of dengue fever cases have increased since 2004. Thailand contributed the largest proportion of cases (17-43% in individual years), followed by India, Brazil and Indonesia. Surveillance of notifiable vector-borne diseases in Germany is able to timely detect spatial and temporal changes of autochthonous an imported infections. Geographic and temporal data obtained by routine surveillance served as a basis for public health recommendations. In addition to surveillance of vector-borne infections in humans, nationwide monitoring programs and inventory techniques for emerging and reemerging vectors and for wildlife disease are warranted. PMID:19030882

Jansen, Andreas; Frank, Christina; Koch, Judith; Stark, Klaus

2008-11-23

147

An Ill Wind? Climate Change, Migration, and Health  

PubMed Central

Background: Climate change is projected to cause substantial increases in population movement in coming decades. Previous research has considered the likely causal influences and magnitude of such movements and the risks to national and international security. There has been little research on the consequences of climate-related migration and the health of people who move. Objectives: In this review, we explore the role that health impacts of climate change may play in population movements and then examine the health implications of three types of movements likely to be induced by climate change: forcible displacement by climate impacts, resettlement schemes, and migration as an adaptive response. Methods: This risk assessment draws on research into the health of refugees, migrants, and people in resettlement schemes as analogs of the likely health consequences of climate-related migration. Some account is taken of the possible modulation of those health risks by climate change. Discussion: Climate-change–related migration is likely to result in adverse health outcomes, both for displaced and for host populations, particularly in situations of forced migration. However, where migration and other mobility are used as adaptive strategies, health risks are likely to be minimized, and in some cases there will be health gains. Conclusions: Purposeful and timely policy interventions can facilitate the mobility of people, enhance well-being, and maximize social and economic development in both places of origin and places of destination. Nevertheless, the anticipated occurrence of substantial relocation of groups and communities will underscore the fundamental seriousness of human-induced climate change.

Barnett, Jon

2012-01-01

148

Wind Transport Near the Poles of Mars: Timescales of Changes in Deposition and Erosion.  

National Technical Information Service (NTIS)

Movement of sediment into and out of polar deposits is closely linked to the polar volatile budget and to changes in wind systems over the course of astronomically induced climate cycles. The present observations of the morphology of polar layered deposit...

P. C. Thomas

1992-01-01

149

Diamagnetic solar wind ions changing the MHD conditions at the heliospheric termination shock  

Microsoft Academic Search

With the two Voyager spacecraft presently flying at solar distances larger than 80 AU, it not only becomes very interesting to study the changing particle environments but also to study the behavior of the distant magnetic fields which are swept out with the solar wind. It is especially challenging to look for the predicted shock features of the magnetic fields

Hans J. Fahr; Klaus Scherer

2005-01-01

150

Winds of Change: Charting the Course for IT in the Twenty-First Century  

ERIC Educational Resources Information Center

In the spring of 2005, the author, the retiring president of EDUCAUSE, was asked to be the keynote speaker at the EDUCAUSE Western Regional Conference. The conference theme was "Winds of Change: Charting the Course for Technology in Challenging Times." What that brought to his mind was the era of the great sailing ships of the eighteenth and…

Hawkins, Brian L.

2007-01-01

151

How Organisations Cope with the Winds of Change  

Microsoft Academic Search

Organisational change is associated with two major research traditions: sociotechnical systems analysis and design on one hand and organisational development on the other. While soci- otechnical analysis and design has collected a huge body of knowledge for designing tasks and pro- cedures of work systems that are both efficient and socially compatible, organisational development has concentrated on organising reflexive collective

Peter Brödner

2000-01-01

152

Comparison of special sensor microwave imager vector wind stress with model-derived and subjective products for the tropical Pacific  

SciTech Connect

The authors address the role of wind data in the development of general ocean circulation model studies. Satellite scatterometry has been proposed, but only minimally implemented, as a means of providing global information on ocean surface wind speed and direction. However, a number of microwave systems have monitored wind speed information on a global scale, some over extended periods of time, which provide day-to-day coverage, compared to the sparse information available from ship or buoy data collections. Recently data from the Defense Meteorological Satellite Program special sensor microwave imager, for the period July 1987 to June 1988 was utilized, in conjunction with conventional data collections to build a model system which included wind directions. The authors here take this data set and use it as a forcing function in a general ocean circulation model study. Their interest is in knowing if this gives results comparable with such data sets built from much more limited observational and subjective analysis. The results are encouraging, and they suggest reexamination of earlier information collections with the idea of reconstructing ocean surface wind speed and direction data sets to be used in further modeling studies.

Busalacchi, A.J.; Atlas, R.M. (NASA Goddard Space Flight Center, Greenbelt, MD (United States)); Hackert, E.C. (Hughes/STX Corp., Lanham, MD (United States))

1993-04-15

153

The effect of solar-wind structures on the magnetosphere: Current sheets and sudden wind shears  

NASA Astrophysics Data System (ADS)

The solar wind is full of strong current sheets and sudden velocity shears. Often the two types of structures are co-located, so 10 or 20 times per day the Earth simultaneously experiences a sudden change in the magnetic-field direction and a sudden change in the solar-wind flow vector. Using data analysis and simulations, the reaction of the Earth's magnetosphere to these sudden changes is explored.

Borovsky, J. E.; Welling, D. T.; Morley, S.; Birn, J.

2011-12-01

154

Improving the textural characterization of trabecular bone structure to quantify its changes: the locally adapted scaling vector method  

NASA Astrophysics Data System (ADS)

We extend the recently introduced scaling vector method (SVM) to improve the textural characterization of oriented trabecular bone structures in the context of osteoporosis. Using the concept of scaling vectors one obtains non-linear structural information from data sets, which can account for global anisotropies. In this work we present a method which allows us to determine the local directionalities in images by using scaling vectors. Thus it becomes possible to better account for local anisotropies and to implement this knowledge in the calculation of the scaling properties of the image. By applying this adaptive technique, a refined quantification of the image structure is possible: we test and evaluate our new method using realistic two-dimensional simulations of bone structures, which model the effect of osteoblasts and osteoclasts on the local change of relative bone density. The partial differential equations involved in the model are solved numerically using cellular automata (CA). Different realizations with slightly varying control parameters are considered. Our results show that even small changes in the trabecular structures, which are induced by variation of a control parameters of the system, become discernible by applying the locally adapted scaling vector method. The results are superior to those obtained by isotropic and/or bulk measures. These findings may be especially important for monitoring the treatment of patients, where the early recognition of (drug-induced) changes in the trabecular structure is crucial.

Raeth, Christoph W.; Mueller, Dirk; Boehm, Holger F.; Rummeny, Ernst J.; Link, Thomas M.; Monetti, Roberto

2005-04-01

155

Large warming trends associated with blocked winds over the Antarctic Peninsula and changes in zonal circulation  

NASA Astrophysics Data System (ADS)

Analysis of surface temperature (ST) anomalies of the Antarctic for the period 1982-1998 has shown that the largest warming trend in the world occurs on the western coast of the Antarctic Peninsula (by approximately 1.0{o}C over the past 20 years). This is associated with related warming of the peripheral seas and decrease of the sea-ice extent (Kwok and Comiso, 2002). This can be studied by considering how zonal winds interact with the mountains (2km high) of the peninsula. Since westerly winds are turned southwards through Coriolis forces, warmer air over the southern ocean is transported to the western side of the Antarctic Peninsula. On its eastern side (warming of approximately 0.5{o}C over the past 20 years), strong southerly katabatic winds overcome the weak northerly synoptically driven flows and flow along the eastern side of the Antarctic Peninsula. However for easterly winds passing over the Weddell Sea, Coriolis forces cause winds which add to the cold katabatic southerly winds from the Antarctic plateau. Both these types of wind cool the east and west sides of the peninsula. Therefore the observed increase in the frequency of westerly winds should cause a net warming, particularly on the western side, as recent synoptic data from the NCEP/ECMWF reanalysis project has shown for the past 20 years (Kwok and Comiso, 2002). This concept has been tested using detailed modelling of the stably stratified atmospheric flows over the peninsula. The idealised 2-layer model of Hunt et al. (2002) for typical mesoscale atmospheric flows with sharp variations in surface roughness and mountainous elevation verifies the above flow behaviour for easterly and westerly winds perpendicular to a `cape' such as the Antarctic Peninsula. Numerical modelling using the UK Met Office Unified Model (UM) at 12km resolution showed a flow response which agrees with observational weather station data on the eastern side. But it is less satisfactory on the western side where the katabatic winds are not (at present) accurately represented. \\vspace{0.1cm} References: \\vspace{0.1cm} Kwok, R. and Comiso, J. C., `Spatial patterns of variability in Antarctic surface temperature: Connections to the Southern Hemisphere Annular Mode and the Southern Oscillation', Geophysical Research Letters, Vol. 29, No. 10, 2002. \\vspace{0.1cm} Hunt, J. C. R., Orr, A., Rottman, J. and Capon, R., `Coriolis effects in mesoscale flows with sharp changes in surface conditions', Submitted to Q. J. Roy. Met. Soc, 2002.

Orr, A.; Hunt, J.; Light, M.; Cresswell, D.

2003-04-01

156

Titan's rotation reveals an internal ocean and changing zonal winds.  

PubMed

Cassini radar observations of Saturn's moon Titan over several years show that its rotational period is changing and is different from its orbital period. The present-day rotation period difference from synchronous spin leads to a shift of approximately 0.36 degrees per year in apparent longitude and is consistent with seasonal exchange of angular momentum between the surface and Titan's dense superrotating atmosphere, but only if Titan's crust is decoupled from the core by an internal water ocean like that on Europa. PMID:18356521

Lorenz, Ralph D; Stiles, Bryan W; Kirk, Randolph L; Allison, Michael D; Del Marmo, Paolo Persi; Iess, Luciano; Lunine, Jonathan I; Ostro, Steven J; Hensley, Scott

2008-03-21

157

Climate change projected fire weather sensitivity: California Santa Ana wind occurrence  

NASA Astrophysics Data System (ADS)

A new method based on global climate model pressure gradients was developed for identifying coastal high-wind fire weather conditions, such as the Santa Ana Occurrence (SAO). Application of this method for determining southern California Santa Ana wind occurrence resulted in a good correlation between derived large-scale SAOs and observed offshore winds during periods of low humidity. The projected change in the number of SAOs was analyzed using two global climate models, one a low temperature sensitivity and the other a middle-temperature sensitivity, both forced with low and high emission scenarios, for three future time periods. This initial analysis shows consistent shifts in SAO events from earlier (September-October) to later (November-December) in the season, suggesting that SAOs may significantly increase the extent of California coastal areas burned by wildfires, loss of life, and property.

Miller, Norman L.; Schlegel, Nicole J.

2006-08-01

158

Integration of remotely-sensed raster data with a vector-based geographical information system for land-use change detection  

Microsoft Academic Search

Methods of land-use change detection are different for raster and vector data types because of the differences in structures of the two data types. Since large amounts of land-use data (derived from existing maps and aerial photographs) are stored in vector format in a Geographical Information System (GIS), there is a need to develop a change detection algorithm for use

N. M. MATTIKALLI

1995-01-01

159

Catastrophic wind damage to North American forests and the potential impact of climate change.  

PubMed

Catastrophic winds from tornadoes and downbursts are a major cause of natural disturbance in forests of eastern North America, accounting for thousands of hectares of disturbed area annually. Wind disturbance shows substantial regional variation, decreasing from the mid-west to the east and from the south-east to New England. In terms of the relative importance among these types of storms, more forest damage results from tornadoes in the south-east and mid-west, while downbursts are the most important type of wind disturbance in the Great Lakes area. Downbursts vary widely in size, but large ones can damage thousands of hectares, while tornadoes are much smaller, seldom affecting more than several hundred hectares. Tornadoes cause the most severe wind disturbances. Site characteristics such as physiography, soil moisture, and soil depth; stand characteristics like density and canopy roughness; and tree characteristics such as size, species, rooting depth, and wood strength, are the factors most recognized as influencing damage patterns. The consequences of wind damage to forests, such as change in environmental conditions, density, size structure, species composition, and successional status, occur on both immediate (hours-to-days) and long-term (months-to-decades) time scales. Most wind disturbances result in the post-disturbance vegetation being comprised of surviving canopy trees, and varying amounts of sprouts, released understory stems, and new seedlings. Stand size structure is usually reduced, and successional status of a forest is often advanced. Diversity can be either increased or decreased, depending on the measure of abundance used to calculate diversity. Because tornadoes and downbursts are in part products of thermodynamic climatic circumstances, they may be affected by anticipated changes in climatic conditions as the 21st century progresses. However, the current understanding of tornado and downburst formation from supercell storms is very incomplete, and climate-change model predictions sufficiently coarse, that predictions of changes in frequency, size, intensity, or timing of these extreme events must be regarded as highly uncertain. Moreover, retrospective approaches that employ tree demography and dendrochronology require prohibitively large sample sizes to resolve details of the relationship between climate fluctuations and characteristics of these storms. To improve predictions of changes in the climatology of these storms, we need improved understanding of the genesis of tornadoes and downbursts within thunderstorms, and greater resolution in global climate models. To improve coping strategies, forest scientists can contribute by giving more attention to how various silvicultural actions influence stand and tree vulnerability. Finally, increased focus on the dynamics of forest recovery and regrowth may suggest management actions that can facilitate desired objectives after one of these unpredictable wind disturbances. PMID:11087033

Peterson, C J

2000-11-15

160

A new Global Observational Dataset for Detecting Changes in Surface Winds and Storm Activity  

NASA Astrophysics Data System (ADS)

Remote Sensing Systems just released a new version of the Special Sensor Microwave Imager (SSM/I) data products. SSM/I is an intercalibrated and unified dataset of continuous satellite observations of surface wind speed, cloud liquid water, water vapor, and rain rate over the global oceans since 1987. In the new Version 6, all six SSM/Is (F08, F10, F11, F13, F14, and F15) have been carefully intercalibrated and a spurious decadal scale trend in wind speed has been corrected. This will now allow investigators to confidently use the SSM/I products for detailed analysis of atmospheric variability at interannual and decadal time scales. Unlike ship data, this satellite dataset provides, for the first time, 19 years of reliable spatially and temporally continuous observations of surface winds (and other cloud-related variables) over the global oceans at 25 km resolution. Here we show global trend maps of surface wind speeds, and analyze in detail patterns in the Atlantic and Pacific extratropical regions. Investigation of changes in storm location is attempted with the aide of rain and cloud liquid water data. A comparison of similar studies we performed using winds from NCEP-NCAR and ERA40 reanalyses, and COADS observations is also addressed.

Ricciardulli, L.; Wentz, F. J.

2006-12-01

161

High-latitude ground-based response to sudden changes in solar wind dynamic pressure  

NASA Astrophysics Data System (ADS)

Sudden changes in the solar wind dynamic pressure have been linked, both theoretically and observationally, to the formation of a number of transient ionospheric phenomena. Still, the precise role that these pressure changes play in the formation of these phenomena remains uncertain. By using a combination of ground-based magnetic measurements from arrays of magnetometers located in Greenland and IMP 8 satellite measurements of the solar wind velocity and density, we have been able to better study the effect that pressure changes have on the high-latitude ionosphere. Our study is based on approximately 2500 hours of solar wind plasma data collected during 1991 and 1992 by the IMP 8 satellite and focuses on step changes of |?p|>2nPa, occurring on a timescale of ?t<15min. We have found that the ground response does not consistently conform to existing theoretical models of field-aligned currents generated by changes in dynamic pressure. We also do not find any explicit dependence on interplanetary magnetic field orientation. These results lead us to believe that the nature of the ground response is due to a more complicated combination of external controls.

Sitar, R. J.; Clauer, C. R.; Friis-Christensen, E.

1996-12-01

162

Changing patterns of West Nile virus transmission: altered vector competence and host susceptibility  

PubMed Central

West Nile virus (WNV) is a flavivirus (Flaviviridae) transmitted between Culex spp. mosquitoes and avian hosts. The virus has dramatically expanded its geographic range in the past ten years. Increases in global commerce, climate change, ecological factors and the emergence of novel viral genotypes likely play significant roles in the emergence of this virus; however, the exact mechanism and relative importance of each is uncertain. Previously WNV was primarily associated with febrile illness of children in endemic areas, but it was identified as a cause of neurological disease in humans in 1994. This modulation in disease presentation could be the result of the emergence of a more virulent genotype as well as the progression of the virus into areas in which the age structure of immunologically naïve individuals makes them more susceptible to severe neurological disease. Since its introduction to North America in 1999, a novel WNV genotype has been identified that has been demonstrated to disseminate more rapidly and with greater efficiency at elevated temperatures than the originally introduced strain, indicating the potential importance of temperature as a selective criteria for the emergence of WNV genotypes with increased vectorial capacity. Even prior to the North American introduction, a mutation associated with increased replication in avian hosts, identified to be under adaptive evolutionary pressure, has been identified, indicating that adaptation for increased replication within vertebrate hosts could play a role in increased transmission efficiency. Although stable in its evolutionary structure, WNV has demonstrated the capacity for rapidly adapting to both vertebrate hosts and invertebrate vectors and will likely continue to exploit novel ecological niches as it adapts to novel transmission foci.

Brault, Aaron C.

2009-01-01

163

Wind-driven changes in Southern Ocean residual circulation, ocean carbon reservoirs and atmospheric CO2  

NASA Astrophysics Data System (ADS)

The effect of idealized wind-driven circulation changes in the Southern Ocean on atmospheric CO2 and the ocean carbon inventory is investigated using a suite of coarse-resolution, global coupled ocean circulation and biogeochemistry experiments with parameterized eddy activity and only modest changes in surface buoyancy forcing, each experiment integrated for 5,000 years. A positive correlation is obtained between the meridional overturning or residual circulation in the Southern Ocean and atmospheric CO2: stronger or northward-shifted westerly winds in the Southern Hemisphere result in increased residual circulation, greater upwelling of carbon-rich deep waters and oceanic outgassing, which increases atmospheric pCO2 by ˜20 ?atm; weaker or southward-shifted winds lead to the opposing result. The ocean carbon inventory in our model varies through contrasting changes in the saturated, disequilibrium and biogenic (soft-tissue and carbonate) reservoirs, each varying by O(10-100) PgC, all of which contribute to the net anomaly in atmospheric CO2. Increased residual overturning deepens the global pycnocline, warming the upper ocean and decreasing the saturated carbon reservoir. Increased upwelling of carbon- and nutrient-rich deep waters and inefficient biological activity results in subduction of unutilized nutrients into the ocean interior, decreasing the biogenic carbon reservoir of intermediate and mode waters ventilating the Northern Hemisphere, and making the disequilibrium carbon reservoir more positive in the mode waters due to the reduced residence time at the surface. Wind-induced changes in the model carbon inventory are dominated by the response of the global pycnocline, although there is an additional abyssal response when the peak westerly winds change their latitude, altering their proximity to Drake Passage and changing the depth extent of the southward return flow of the overturning: a northward shift of the westerly winds isolates dense isopycnals, allowing biogenic carbon to accumulate in the deep ocean of the Southern Hemisphere, while a southward shift shoals dense isopycnals that outcrop in the Southern Ocean and reduces the biogenic carbon store in the deep ocean.

Lauderdale, Jonathan M.; Garabato, Alberto C. Naveira; Oliver, Kevin I. C.; Follows, Michael J.; Williams, Richard G.

2013-10-01

164

Uncovering spider silk nanocrystalline variations that facilitate wind-induced mechanical property changes.  

PubMed

Spider major ampullate (MA) silk varies in mechanical properties when spun in different environments. Amino acid compositional changes induced by variations in MaSp1 and MaSp2 expression, and various biochemical and physiological glandular processes induce silk property variability. Quantifying the contributions of these mechanisms on silk variability may facilitate the development of silk biomimetics. Wind is a medium that induces variations in MA silk mechanics. We exposed the spider Cyclosa mulmeinensis to wind and measured the amino acid composition, tensile mechanics, and crystalline structure of its MA silk using HPLC, tensile tests, and X-ray diffraction. We found the mechanical properties of MA silks from spiders exposed to wind to differ from unexposed spiders. The amino acid compositions did not differ, but X-ray diffraction found a lower crystal density and greater ?-sheet alignment relative to the fiber axis in the silks of spiders exposed to wind. We found no evidence that the mechanical property variations were a product of profound changes to the alignment of the protein within the amorphous region. We conclude that variations in the density and alignment of the crystalline ?-sheets, probably accompanied by some alignment change in the amorphous region as a result of "stretching" during spinning of the silk, probably explains the mechanical property variations that we found across treatment subgroups. As C. mulmeinensis MA silk increases both in strength and elasticity when the spiders are exposed to wind, bioengineers may consider it as a model for the development of high-performance silk biomimetics. PMID:23947397

Blamires, Sean J; Wu, Chao-Chia; Wu, Chung-Lin; Sheu, Hwo-Shuenn; Tso, I-Min

2013-09-05

165

Recent changes in measured wind in the NE Atlantic and variability of correlation with NAO  

NASA Astrophysics Data System (ADS)

The paper deals with wind measurements, recorded since the 1950s, at twelve meteorological stations along a transect near the westernmost European border, between 64° and 44° N. Extreme wind speed tends to decrease sharply near the northern boundary (at Reykjavick), near the middle of the study area (at Shannon and Valentia) and near the southern boundary (at Brest and Cap Ferret), to increase at Thorshavn, with less significant trends at the other stations. Average wind speeds confirm the above tendencies, with an additional increasing speed at Lerwick, Kirkwall, Malin Head, Belle-Ile and Cap Ferret. To compare changes in wind activity, the data have been subdivided into three periods: until 1975, 1976-1992 and 1993-2008. Frequencies have been computed also for the "winter" (October to March) period, per quadrants, and for occurrences exceeding the speed of 15 m s-1. At Reykjavick a recent increase in the frequency of strong winds has occurred from various directions. Between 62° N (Thorshavn) and 59° N (Kirkwall) strong wind has been increasing since 1975. Minor changes can be observed at Stornoway, whereas at Malin Head the greatest increase for southerlies and westerlies is observed during the 1976-1992 period. At Belmullet, the frequency of strong southerlies has almost doubled since 1992, while at Shannon and Valentia it remains quite low. Finally at Brest and Belle-Ile, westerlies are predominant among winds >15 m s-1. Important changes in time and latitude appear in the correlation with the NAO (North Atlantic Oscillation) index. The highest correlation coefficients, calculated with monthly or seasonal means between the early 1950s and 1975, are observed from between 58° N (Stornoway) and Iceland, whereas low positive coefficients are reported more south. During the period 1976-1992, when increasing NAO index is predominant, positive correlation improves southwards as far as 54° (Belmullet) with some improvement also at Shannon and Valentia, while it remains low or even negative near the French Atlantic coast. Finally in the 1993-2008 period, correlation improves for all the stations south of 54° N (Belmullet), while it weakens more north.

Pirazzoli, P. A.; Tomasin, A.; Ullmann, A.

2010-10-01

166

Wind of change: new insights on the ecology and evolution of pollination and mating in wind-pollinated plants  

PubMed Central

Background The rich literature that characterizes the field of pollination biology has focused largely on animal-pollinated plants. At least 10 % of angiosperms are wind pollinated, and this mode of pollination has evolved on multiple occasions among unrelated lineages, and hence this discrepancy in research interest is surprising. Here, the evolution and functional ecology of pollination and mating in wind-pollinated plants are discussed, a theoretical framework for modelling the selection of wind pollination is outlined, and pollen capture and the occurrence of pollen limitation in diverse wind-pollinated herbs are investigated experimentally. Scope and Conclusions Wind pollination may commonly evolve to provide reproductive assurance when pollinators are scarce. Evidence is presented that pollen limitation in wind-pollinated plants may not be as common as it is in animal-pollinated species. The studies of pollen capture in wind-pollinated herbs demonstrate that pollen transfer efficiency is not substantially lower than in animal-pollinated plants as is often assumed. These findings challenge the explanation that the evolution of few ovules in wind-pollinated flowers is associated with low pollen loads. Floral and inflorescence architecture is crucial to pollination and mating because of the aerodynamics of wind pollination. Evidence is provided for the importance of plant height, floral position, and stamen and stigma characteristics in promoting effective pollen dispersal and capture. Finally, it is proposed that geitonogamous selfing may alleviate pollen limitation in many wind-pollinated plants with unisexual flowers.

Friedman, Jannice; Barrett, Spencer C. H.

2009-01-01

167

Surges, atmospheric pressure and wind change and flooding probability on the Atlantic coast of France  

Microsoft Academic Search

A statistical study of hourly tide-gauge records at Saint-Gildas, Saint-Nazaire, Port Tudy, Brest, Le Conquet and Roscoff, as well of three-hourly wind and air pressure records at Belle Ile and Ouessant over the last 50 years, has made possible the definition of the main meteorological factors which are associated with the development of positive or negative surges. Recent changes in

Paolo Antonio PIRAZZOLI

2000-01-01

168

Simulated response of the Southern Ocean to wind changes: towards the role of mesoscale eddies  

NASA Astrophysics Data System (ADS)

The role of ocean mesoscale eddies in the Southern Ocean response to recent wind changes is explored with a suite of realistic global ocean simulations at increasing horizontal resolution. Southern Ocean mesoscale eddies are known to be critical in the meridional redistribution of tracers, and are suggested to affect how the Southern Ocean responds to wind changes, takes up heat, and exchanges CO2 with the atmosphere. By employing the ocean general circulation model NEMO-LIM, ocean simulations with horizontal resolutions of 1/2°, 1/4°, and 1/12°, i.e. ranging from non-eddying to eddy-resolving, are performed and compared. In particular, a "two-way" nesting technique is used to refine the ocean grid up to 1/12° in the Southern Ocean. The ocean models are forced with the CORE v.2 atmospheric reanalysis during the period 1948-2007, and companion experiments under a repeated-annual-cycle forcing are used to detect model spurious drifts. First, we assess the effect of explicitly simulated eddies on ocean mean properties. Mesoscale eddies are shown to modify the mixed layer depth and the upper-ocean density, with potential effects on the formation properties of Subantarctic Mode Waters. Second, we explore the role of mesoscale eddies in affecting the ocean circulation sensitivity to the sustained increase of Southern Hemisphere winds during the past decades. Whereas the non-eddying simulations exhibit large increases of the Antarctic Circumpolar Current transport, the 1/4° and 1/12° models are less sensitive to the wind increase, in better agreement with available observations. These results show a clear effect of model resolution on the Southern Ocean response to climate variability and change.

Patara, Lavinia; Böning, Claus; Biastoch, Arne

2013-04-01

169

Penalized Maximal F Test for Detecting Change Points of Temperature and Wind Speed Data Series  

NASA Astrophysics Data System (ADS)

The homogeneity of the climate record continues to receive considerable attention. Time series are commonly contaminated by non-climatic discontinuities that result from station relocations, observation time changes, and station specific trends related to environmental changes in the proximity of the observation sites. Several statistical methods have been proposed for detecting undocumented shifts. Wang Xiaolan et al. proposed the penalized maximal F test (PMFT) for detecting undocumented mean shifts that are not accompanied by any sudden change in the linear trend of time series. This method is based on the penalized maximal F test, which are embedded in a recursive testing algorithm, with the lag-1 autocorrelation (if any) of the time series being empirically accounted for. In this research the PMFT method is used for detecting the shifts of long time series of temperature and wind speed data series over China. The monthly average temperature data of about tens of meteorological observing stations and the annual average wind speed data of 753 meteorological observing stations have been detected. The results show that this homogeneity detection method works well for these two meteorological data series over China. 1. Results of monthly average temperature data series To create a reference time series is sometimes very useful for homogeneity detection, while it is difficult to get a good reference time series especially for the hundred-year long temperature data with a lot of year data lost over China. The PMFT method are used without building a references series to detecting the change points of the monthly average maximum temperature of twelve meteorological stations and the monthly average minimum temperature of twenty-nine stations. The results show that this method is fit for the homogeneous detection and we needn't interpolating the data and building a reference time series before the detection. Although discontinuities in temperature time series can be caused by any number of changes in, for example, sensor type, and even the observation schedule, station relocations are the likely cause of the majority of abrupt shifts identified in the temperature series evaluated here. 2. Results of annual average wind speed data series 52 of the data series are too short to be detected among 753 meteorological observing stations. A total of 356 change points over 271 stations are detected of the annual average wind speed time series, which accounts for 38.7% of the evaluated stations. The homogeneous data series are of 231 stations and another 199 stations are not significant that can be considered as homogeneous, which accounts for 61.3% of the evaluated stations. It is found that the data of 61.3% stations are homogeneity among the detected 701 stations, which shows that the homogeneity of the annual average wind speed is good. The change points of the annual average wind speed range from 1 to 2. The changes of instrument and location are the main reason for the non-homogeneity, while the change of the type of the observation instrument for the wind speed is the most important reason for the non-homogeneity of the annual average wind speed over China. The environment change seems not so remarkable, because the relocation and the instrument change may take place at the same time to conceal the effect of the environment change. All of the works we have done are the preliminary experiments of using this method. Although we get some results, there are still a lot of works need to do because the wind speed data are so special and the probability distribution are not the exact Gaussian distribution. At the same time the data of the wind speed are affected mostly by the topography and the barriers aside of the observation fields. The use of reference series can help to diminish departure from Gaussian distribution. We will do more experiments on detecting of the wind speed data. What the important thing is that rely on most detail metadata information to help the work of homogeneity detection.

Cao, L.; Liu, X.; Li, Q.

2009-04-01

170

Tracking Changes in Winds and Ocean Currents in the South Atlantic Using Terrigenous Sediments  

NASA Astrophysics Data System (ADS)

Terrigenous sediments in the ocean can provide constraints on key climate variables such as winds and surface and deep currents. Sediments are brought to the ocean via river runoff, winds and ice, and are redistributed in the ocean by currents. Thus provenance and flux variations reflect the pathways of distribution. Temporal changes in sediment provenance may result from latitudinal wind shifts and ocean current patterns due to climate changes. In the South Atlantic, the pattern of clay minerals in surface sediments tracks the pattern of modern surface currents. Provenance boundaries cross large bathymetric features, indicating that surface currents are the first order control on terrigenous sediment distributions. Surface sediment Sr isotope ratios show systematic variations reflecting the geologic age of the sources. Southward from the Equator, South American sources show a gradient from from old (Brazil Craton) to young (Andes), and this is reflected in the Sr isotopes in proximal sediments. It appears to be possible to separate contributions from wind and surface and deep currents using provenance methods. South of 20oS westerly winds dominate, and South American sources are the most likely aeolian contributions. A counterclockwise gyre composed of the Benguela Current (fed partly by the Agulhas Current from the Indian Ocean), and the Equatorial, Brazil, and Falklands currents dominate the surface currents. Convergence of currents (the Agulhas Retroflection and Malvinas Confluence) produce areas that are potentially sensitive monitors of wind-driven circulation changes. Terrigenous sediment provenance studies in strategically chosen areas are powerful tools to constrain changes in wind, wind driven and deep circulation in paleoceanographic/paleoclimate studies. The Southern Cape Basin illustrates the utility of provenance studies in paleoclimate applications. Ancient continental crust of SE Africa is the source of Mozambique Channel detritus with with very high Sr isotope ratios. The Agulhas Current and its leakage into the Atlantic carries this sediment to the southern Cape Basin. North of the Walvis Ridge, surface currents move detritus from the Archean northward, away from the Cape Basin. Within the Cape Basin the detrital flux is low, and southwest Africa is dominated by younger sources. The circum-Antarctic current carries detritus with a large young volcanic contribution, and a gradient to lower Sr isotope ratios southward from the Cape Basin reflects the relative contributions of the Agulhas and circum-Antarctic currents. Downcore records from southern Cape Basin drift show striking climate-correlated variations in sediment provenance that reflect variations in the contribution of detritus from the Agulhas Current. End member explanations are changes in the Agulhas Current (its detrital load or the magnitude of "leakage") and in contributions from either Cape Basin or circum-Antarctic sources. Ongoing work will constrain the patterns of Holocene and LGM variations in provenance and flux and test these alternatives.

Hemming, S. R.; Goldstein, S. L.; Franzese, A. M.; Rutberg, R. L.; Piotrowski, A. M.

2002-12-01

171

Wind power: Addressing wildlife impacts, assessing effects on tourism, and examining the link between climate change perceptions and support  

NASA Astrophysics Data System (ADS)

As the world's most rapidly growing source of energy, wind power has vast potential for mitigating climate change and advancing global environmental sustainability. Yet, the challenges facing wind energy remain both complex and substantial. Two such challenges are: 1) wildlife impacts; and 2) perceived negative effects on tourism. This dissertation examines these challenges in a multi-paper format, and also investigates the role that climate change perceptions play in garnering public support for wind power. The first paper assesses optimal approaches for addressing wind power's wildlife impacts. Comparative analysis reveals that avian mortality from turbines ranks far behind avian mortality from a number of other anthropogenic sources. Additionally, although bats have recently emerged as more vulnerable to wind turbines than birds, they are generally less federally protected. The Migratory Bird Treaty Act (MBTA) protects over 800 bird species, regardless of their threatened or endangered status. Moreover, it criminalizes the incidental take of birds without a permit and simultaneously grants no permits for such incidental take, thereby creating a legal conundrum for the wind industry. An examination of the legislative and case history of the MBTA, however, reveals that wind operators are not likely to be prosecuted for incidental take if they cooperate with the U.S. Fish & Wildlife Service (FWS) and take reasonable steps to reduce siting and operational impacts. Furthermore, this study's analysis reveals modest wildlife impacts from wind power, in comparison with numerous other energy sources. Scientific-research, legal, and policy recommendations are provided to update the present legal and regulatory regime under the MBTA and to minimize avian and bat impacts. For instance, FWS should: establish comprehensive federal guidelines for wind facility siting, permitting, monitoring, and mitigation; and promulgate regulations under the MBTA for the issuance of incidental take permits at wind facilities. Equal protections for bats are also recommended. In examining the potential effect of offshore wind power on coastal tourism, the second paper reports the findings of a summer 2007 survey of over 1,000 out-of-state tourists at Delaware beaches. Randomly sampled beachgoers were shown photo-simulations of wind turbines at increasing distances from shore and asked how each simulation would affect visitation. With wind turbines located six miles offshore, approximately one-quarter would switch to a different beach. This stated avoidance, however, diminishes with increasing wind project distance from shore. Additionally, stated avoidance of a beach with turbines six miles offshore is exceeded by: avoidance of a beach with an equidistant, inland, fossil fuel power plant; attraction to a beach in order to see turbines six miles offshore; and the likelihood of paying for an offshore wind boat tour. Further, logistic regression modeling reveals that neither trip cost nor income significantly influences the likelihood of visiting a beach with offshore wind. These findings suggest that to limit beach avoidance, offshore wind developers could site wind facilities further from shore, particularly in areas with high recreational use. Moreover, with wind turbines six miles offshore serving more as an attraction than as a deterrent, offshore wind development may, in fact, bolster local tourism revenues. The third study examines public perceptions of climate change and the link between those perceptions and support for wind power, both in general and with respect to specific offshore sites. Analyzing data from five surveys, this research uncovers low climate awareness and concern levels overall. Respondents demonstrate a poor understanding of climate change impacts and of how to effectively address climate change. In accordance with the New Ecological Paradigm, still fewer are concerned about climate change. The issue ranks 6th in Delaware and 8th in Cape Cod as a reason for local project support, behind such issues as energy independence

Lilley, Meredith Blaydes

172

Global effects of changes in wind forcing of Southern Indian Ocean  

SciTech Connect

An identical twin numerical experiment has been performed using the global ocean circulation model of Semtner and Chervin. The wind forcing within a band of 120[degree] East [+-] 45[degrees] and 50[degrees] South [+-] 5[degrees] was varied smoothly in space and time to be approximately 4% greater for the twin run than the original. The twin experiment was run for 60 model days. Within nine days small changes of mass transport of the N. Guiana current were observed. Within 24 days changes appeared in mass transport of Pacific Equatorial Rossby waves, and after 60 days mass transport changes were seen in all ocean basins. Within three days small differences in 160 m (mid-thermocline) temperature appeared in the Atlantic basin. Within thirty days, similar changes were evident globally. Similar results were found for mid-thermocline horizontal velocity. These results imply a predictability limit to the accuracy of ocean circulation models due to rapid communication of wave energy between ocean basins. Changes to Pacific Equatorial Rossby wave transport imply possible effects on El Nino by Southern Indian Ocean winds via oceanic coupling.

Altman, D.B. (Northwest Research Assoc., Bellevue, WA (United States)); Semtner, A.J. (Naval Postgraduate School, Monterey, CA (United States)); Chervin, R.M. (National Center for Atmospheric Research, Boulder, CO (United States))

1990-01-09

173

Electrostatic Solitary Waves in the Solar Wind: Evidence for Instability at Solar Wind Current Sheets  

NASA Astrophysics Data System (ADS)

A strong spatial association between bipolar electrostatic solitary waves (ESWs) and magnetic current sheets (CSs) in the solar wind is reported here for the first time. This association requires that the plasma instabilities (e.g., Buneman, electron two stream) which generate ESWs are preferentially localized to solar wind CSs. Distributions of CS properties (including shear angle, thickness, solar wind speed, and vector magnetic field change) are examined for differences between CSs associated with ESWs and randomly chosen CSs. Possible mechanisms for producing ESW-generating instabilities at solar wind CSs are considered, including magnetic reconnection.

Malaspina, D. M.; Newman, D. L.; Wilson, L. B., III; Goetz, K.; Kellogg, P. J.; Kersten, K.

2013-02-01

174

The Nazca–South America Euler vector and its rate of change  

Microsoft Academic Search

We present velocities relative to the South American plate for five GPS stations on the Nazca plate and use these measurements to estimate the modern Euler vector. We find a pole at 55.8°N, 92.5°W with a rotation rate of 0.60°\\/Myr. Because the GPS station at Easter Island appears to be moving at approximately 6.6 mm\\/yr relative to the other Nazca

Eric Kendrick; Michael Bevis; Robert Smalley Jr; Benjamin Brooks; Rodrigo Barriga Vargas; Eduardo Laur??a; Luiz Paulo Souto Fortes

2003-01-01

175

Changes in glucose-6-phosphate dehydrogenase activity in Indian desert malaria vector Anopheles stephensi during aging.  

PubMed

Malaria parasite requires a specific time to replicate and disseminate in the mosquito's body before transmission to nai?ve hosts can occur. Vector control has a proven record in the prevention and control of malaria. The evaluation of vector control strategies requires accurate methods of predicting mosquito age. Anopheles stephensi is the principal malaria vector of the desert part of India. The objective of this study was to correlate the age of laboratory reared and field collected adults of An. stephensi with the glucose-6-phosphate dehydrogenase (g6pd) activity. The measurement of g6pd activity was carried out in a UV-vis spectrophotometer. The g6pd activity in the males and females An. stephensi was inversely proportional to their age. A significant correlation of the g6pd activity was recorded between the field collected and laboratory reared mosquitoes. The g6pd activity in the males An. stephensi was found to be significantly higher than the females. The finding of the present study is useful for the prediction of the age of males and females An. stephensi. PMID:22542393

Mohanty, Suman Sundar; Singh, Karam Vir; Bansal, Shiv Kumar

2012-04-20

176

Global Climate Change and Its Potential Impact on Disease Transmission by Salinity-Tolerant Mosquito Vectors in Coastal Zones  

PubMed Central

Global climate change can potentially increase the transmission of mosquito vector-borne diseases such as malaria, lymphatic filariasis, and dengue in many parts of the world. These predictions are based on the effects of changing temperature, rainfall, and humidity on mosquito breeding and survival, the more rapid development of ingested pathogens in mosquitoes and the more frequent blood feeds at moderately higher ambient temperatures. An expansion of saline and brackish water bodies (water with <0.5?ppt or parts per thousand, 0.5–30?ppt and >30?ppt salt are termed fresh, brackish, and saline respectively) will also take place as a result of global warming causing a rise in sea levels in coastal zones. Its possible impact on the transmission of mosquito-borne diseases has, however, not been adequately appreciated. The relevant impacts of global climate change on the transmission of mosquito-borne diseases in coastal zones are discussed with reference to the Ross–McDonald equation and modeling studies. Evidence is presented to show that an expansion of brackish water bodies in coastal zones can increase the densities of salinity-tolerant mosquitoes like Anopheles sundaicus and Culex sitiens, and lead to the adaptation of fresh water mosquito vectors like Anopheles culicifacies, Anopheles stephensi, Aedes aegypti, and Aedes albopictus to salinity. Rising sea levels may therefore act synergistically with global climate change to increase the transmission of mosquito-borne diseases in coastal zones. Greater attention therefore needs to be devoted to monitoring disease incidence and preimaginal development of vector mosquitoes in artificial and natural coastal brackish/saline habitats. It is important that national and international health agencies are aware of the increased risk of mosquito-borne diseases in coastal zones and develop preventive and mitigating strategies. Application of appropriate counter measures can greatly reduce the potential for increased coastal transmission of mosquito-borne diseases consequent to climate change and a rise in sea levels. It is proposed that the Jaffna peninsula in Sri Lanka may be a useful case study for the impact of rising sea levels on mosquito vectors in tropical coasts.

Ramasamy, Ranjan; Surendran, Sinnathamby Noble

2012-01-01

177

A mechanism for decadal changes of ENSO behavior: roles of background wind changes  

Microsoft Academic Search

This study explains why a number of El Nino properties (period, amplitude, structure, and propagation) have changed in a coherent manner since the late 1970s and why these changes had almost concurred with the Pacific decadal climate shift. Evidence is presented to show that from the pre-shift (1961-1975) to the post-shift (1981-1995) epoch, significant changes in the tropical Pacific are

B. Wang; S. I. An

2002-01-01

178

Correlations of atmospheric dynamics with solar wind-induced changes of air-earth current density into cloud tops  

Microsoft Academic Search

We analyze reported correlations between solar activity and weather and climate and show that in six independent data sets there is a correlation of measured changes in atmospheric dynamics with meaqured or inferred changes in vertical atmospheric air-earth current density. The current density changes are due to external modulation of the global electric circuit by the solar wind. We describe

Brian A. Tinsley

1996-01-01

179

Observations of the transient fluctuations of the solar wind ion flux at the boundaries of the pressure change  

NASA Astrophysics Data System (ADS)

Plasma spectrometer BMSW was developed for the measurements of the main solar wind and magnetosheath plasma parameters - velocity, temperature, ion density and ion flux with high time resolution onboard the "Spektr-R" project. Since the beginning of measurements on August 2011 a lot of experimental data were received allowing to study, in particular, fine structure of the solar wind, pressure pulses, boundaries and so on. The paper presents case study results of several fast variable and transient events, connected with the crossing of sharp boundaries of the solar wind pressure pulses. It was shown the presence of large amplitude fluctuations in the solar wind ion flux with the period about 6-9 seconds close to the boundary of pressure change. Power spectra of these solar wind ion flux fluctuations revealed low-frequency and high frequency parts with different slopes and with the kink near 1Hz.

Borodkova, Natalia; Zastenker, Georgy; Chugunova, Olga

2013-04-01

180

Minkowski space non-Abelian classical solutions with noninteger winding number change  

NASA Astrophysics Data System (ADS)

Working in a spherically symmetric ansatz in Minkowski space, we discover new solutions to the classical equations of motion of pure SU(2) gauge theory. These solutions represent spherical shells of energy, which move inward near the speed of light at early times, excite the region of space around the origin at intermediate times, and move outward at late times. The solutions change the winding number in bounded regions centered at the origin by noninteger amounts. They also produce a noninteger topological charge in these regions. We show that the previously discovered solutions of Lüscher and Schechter also have these properties.

Farhi, Edward; Khoze, Valentin V.; Singleton, Robert, Jr.

1993-06-01

181

Woodland Cover Change Assessment Using Decision Trees, Support Vector Machines and Artificial Neural Networks Classification Algorithms  

Microsoft Academic Search

Land cover change assessment is one of the main applications of remote sensed data. Change in forest cover have widespread effects on the provision of ecosystem services, and provide important feedbacks to climate change and biodiversity. Moreover, it will be extremely critical if the accuracy of image interpretation can be improved for better understanding the change of forest. Parametric methods

Xidong Jiang; Meizhen Lin; Junlei Zhao

2011-01-01

182

Global changes in extreme wind waves, marine storminess and cyclone activity  

NASA Astrophysics Data System (ADS)

We used in our analysis the longest time series of visual wave observations from the International Comprehensive Ocean-Atmosphere Data Set (ICOADS) archive of marine meteorological variables, covering the period form 1885 to 2007. Data were subject of the precise quality control and homogenization. For the whole Northern Hemisphere and several regions of the Southern Hemisphere we estimated secular changes in mean sea, swell and significant wave height as well as tendencies in extreme wave parameters. These were estimated from both IVD (initial value distribution) and POT (peak over threshold) methods using both VOS and long-term model wave hindcasts for minimization of sampling errors. While mean wave height demonstrates upward tendencies in the Northern Hemisphere mid latitudes (up to 8 cm/decade) over the whole 20th century, changes in extreme waves experience strong interdecadal variability in the first half of the century and start to grow only in 1950. During the last two decades (1990-2007) extreme significant wave height shows a light decrease compared to 1970s and 1980s. The observed changes are considered in a view of the contribution of wind sea and swell in the variability of significant wave height. Variations in different wave components were associated with the changes in cyclone activity which was quantifies using numerical storm tracking of long-term reanalysis products. For the last 4 decades we also performed the analysis of variability and change in wind wave periods and directions and associated changes in the locations of storm trajectories and cyclone composites.

Gulev, S.; Grigorieva, V.

2009-09-01

183

Modeled response of the West Nile virus vector Culex quinquefasciatus to changing climate using the dynamic mosquito simulation model  

NASA Astrophysics Data System (ADS)

Climate can strongly influence the population dynamics of disease vectors and is consequently a key component of disease ecology. Future climate change and variability may alter the location and seasonality of many disease vectors, possibly increasing the risk of disease transmission to humans. The mosquito species Culex quinquefasciatus is a concern across the southern United States because of its role as a West Nile virus vector and its affinity for urban environments. Using established relationships between atmospheric variables (temperature and precipitation) and mosquito development, we have created the Dynamic Mosquito Simulation Model (DyMSiM) to simulate Cx. quinquefasciatus population dynamics. The model is driven with climate data and validated against mosquito count data from Pasco County, Florida and Coachella Valley, California. Using 1-week and 2-week filters, mosquito trap data are reproduced well by the model ( P < 0.0001). Dry environments in southern California produce different mosquito population trends than moist locations in Florida. Florida and California mosquito populations are generally temperature-limited in winter. In California, locations are water-limited through much of the year. Using future climate projection data generated by the National Center for Atmospheric Research CCSM3 general circulation model, we applied temperature and precipitation offsets to the climate data at each location to evaluate mosquito population sensitivity to possible future climate conditions. We found that temperature and precipitation shifts act interdependently to cause remarkable changes in modeled mosquito population dynamics. Impacts include a summer population decline from drying in California due to loss of immature mosquito habitats, and in Florida a decrease in late-season mosquito populations due to drier late summer conditions.

Morin, Cory W.; Comrie, Andrew C.

2010-09-01

184

Changes in extreme wind speeds in NW Europe simulated by generalized linear models  

NASA Astrophysics Data System (ADS)

We investigate the capability of generalized linear models (GLMs) to simulate sequences of daily maximum wind speed (DMWS), at a selection of locations in NW Europe. Models involving both the gamma and Weibull distributions have been fitted to the NCEP reanalysis data for the period 1958-1998. In simulations, these models successfully reproduce the observed increasing trends up to 0.3 m/s per decade in coastal or oceanic locations for the wintertime and the decreasing trends down to -0.2 m/s per decade in inland Europe for the summertime. Annually extreme winds exhibit an increasing tendency (with median estimates up to 0.6 m/s per decade) at the studied locations. The gamma model slightly overestimates the upper percentiles of the wind speed distribution, but reproduces trends better than the Weibull model. In both the NCEP data and GLM simulations, local extreme DMWS events (defined in terms of threshold exceedances) have increased dramatically in frequency during winter; decreasing trends are more common in summer. The NCEP data indicate similar trends in the frequencies of large-scale windy events (defined via simultaneous exceedances at 2 or more locations). Overall, these events have increased in number; at the scale of the North Sea basin, their number may have changed from 3-5 days per year during the earlier decades, to 5-7 days per year during later decades based on observational estimates. An increase in the frequency of large-scale extreme winter storms is implied. The GLMs underestimate these large-scale event frequencies, and provide imprecise estimates of the corresponding secular trends. These problems could be rectified by using a better representation of spatial dependence. The present results suggest that GLMs offer a useful tool to study local climate extremes in the context of changing climate distributions; they also provide some pointers towards improving the representation of extremes at a regional scale.

Yan, Z.; Bate, S.; Chandler, R. E.; Isham, V.; Wheater, H.

2006-01-01

185

Potential effects of climate change on distribution and activity of insect vectors of grapevine pathogens  

Microsoft Academic Search

The impact of changing climatic conditions on viticulture is currently mainly discussed with respect to alterations in grape physiology, adaptation of cultivars and cultural practice. However, pests and diseases of grapevine are influenced by changing climate, too. They are affected either directly through impacts on their life history and epidemiology or indirectly by changes of grapevine physiology and phenology. This

Élisabeth BOUDON-PADIEU; Michael MAIXNER

186

[Changes in vectors of endogenously generated ion currents in light-induced germination of turions of Spirodela polyrrhiza].  

PubMed

Nondormant turions of Spirodela polyrhiza (L.) Schleiden were utilized to investigate endogenous ion currents in light-induced germination and early growing processes of higher plants. A small outward current was detected at the ventral side of the turions near the pocket containing the most developed sprout primordium. After a light pulse, the direction of the endogenous current changed from outward to inward. These ion currents are most likely conditioned by unspecific diffusion of cations (probably H+) inside the cell. Three-day-old sprouts of Spirodela showed the highest inward current near the sprout base which decreases toward its edge. Newly formed sprouts demonstrated a strong gravity effect (bending), which was preceded by a lowering of the Z-component of vectors close to the sprout base after a change of the turion fixation. PMID:12298209

Sokolovski?, S G; Appenroth, K J

187

Changes in vector species composition and current vector biology and behaviour will favour malaria elimination in Santa Isabel Province, Solomon Islands  

PubMed Central

Background In 2009, Santa Isabel Province in the Solomon Islands embarked on a malaria elimination programme. However, very little is known in the Province about the anopheline fauna, which species are vectors, their bionomics and how they may respond to intensified intervention measures. The purpose of this study was to provide baseline data on the malaria vectors and to ascertain the possibility of successfully eliminating malaria using the existing conventional vector control measures, such as indoor residual spraying (IRS) and long-lasting insecticidal nets (LLIN). Methods Entomological surveys were undertaken during October 2009. To determine species composition and distribution larval surveys were conducted across on the whole island. For malaria transmission studies, adult anophelines were sampled using human landing catches from two villages - one coastal and one inland. Results Five Anopheles species were found on Santa Isabel: Anopheles farauti, Anopheles hinesorum, Anopheles lungae, Anopheles solomonis, and Anopheles nataliae. Anopheles hinesorum was the most widespread species. Anopheles farauti was abundant, but found only on the coast. Anopheles punctulatus and Anopheles koliensis were not found. Anopheles farauti was the only species found biting in the coastal village, it was incriminated as a vector in this study; it fed early in the night but equally so indoors and outdoors, and had a low survival rate. Anopheles solomonis was the main species biting humans in the inland village, it was extremely exophagic, with low survival rates, and readily fed on pigs. Conclusion The disappearance of the two major vectors, An. punctulatus and An. koliensis, from Santa Isabel and the predominance of An. hinesorum, a non-vector species may facilitate malaria elimination measures. Anopheles farauti was identified as the main coastal vector with An. solomonis as a possible inland vector. The behaviour of An. solomonis is novel as it has not been previously found biting humans in any numbers. Both species appear to be short-lived, a characteristic that will limit their transmission potential. The early night feeding behaviour and a degree of outdoor biting seen in An. farauti and particularly in An. solomonis will require that their response to IRS and LLIN be closely monitored. In coastal villages, where large, favourable breeding sites allow for high numbers of An. farauti may require the addition of larval control to achieve elimination.

2011-01-01

188

Secular changes in the xenon and krypton abundances in the solar wind recorded in single lunar grains  

Microsoft Academic Search

NOBLE gases implanted into the lunar surface trace elemental and isotopic abundances in the solar wind during the Sun's lifetime, and so potentially provide a valuable record of changing physical processes on the Sun. But the interpretation of this record is not straightforward, as it has proved difficult to discriminate the effects of solar variations from changes due to subsequent

Rainer Wieler; Karl Kehm; Alexander P. Meshik; Charles M. Hohenberg

1996-01-01

189

Relative Velocity and Vectors  

NSDL National Science Digital Library

This activity is designed to enhance student comprehension of air and wind velocity, through the use of real time flight data. Students will read about relative velocity, complete a work sheet on vectors, and then gather and analyze real world data. All of the materials, including links to sites for data collection, are provided in this learning object. After completing the activity, students will be able to define relative velocity, add and subtract vectors, and determine aircraft speed using raw data.

Weaver, David

2009-11-16

190

The Abrupt Changes in the Photospheric Magnetic and Lorentz Force Vectors during Six Major Neutral-line Flares  

NASA Astrophysics Data System (ADS)

We analyze the spatial and temporal variations of the abrupt photospheric magnetic changes associated with six major flares using 12 minute, 0farcs5 pixel-1 vector magnetograms from NASA's Helioseismic and Magnetic Imager instrument on the Solar Dynamics Observatory satellite. The six major flares occurred near the main magnetic neutral lines of four active regions, NOAA 11158, 11166, 11283, and 11429. During all six flares the neutral-line field vectors became stronger and more horizontal, in each case almost entirely due to strengthening of the horizontal field components parallel to the neutral line. In all six cases the neutral-line pre-flare fields were more vertical than the reference potential fields, and collapsed abruptly and permanently closer to potential-field tilt angles during every flare, implying that the relaxation of magnetic stress associated with non-potential tilt angles plays a major role during major flares. The shear angle with respect to the reference potential field did not show such a pattern, demonstrating that flare processes do not generally relieve magnetic stresses associated with photospheric magnetic shear. The horizontal fields became significantly and permanently more aligned with the neutral line during the four largest flares, suggesting that the collapsing field is on average more aligned with the neutral line than the pre-flare neutral-line field. The vertical Lorentz force had a large, abrupt, permanent downward change during each of the flares, consistent with loop collapse. The horizontal Lorentz force changes acted mostly parallel to the neutral line in opposite directions on each side, a signature of the fields contracting during the flare, pulling the two sides of the neutral line toward each other. The greater effect of the flares on field tilt than on shear may be explained by photospheric line-tying.

Petrie, G. J. D.

2012-11-01

191

THE ABRUPT CHANGES IN THE PHOTOSPHERIC MAGNETIC AND LORENTZ FORCE VECTORS DURING SIX MAJOR NEUTRAL-LINE FLARES  

SciTech Connect

We analyze the spatial and temporal variations of the abrupt photospheric magnetic changes associated with six major flares using 12 minute, 0.''5 pixel{sup -1} vector magnetograms from NASA's Helioseismic and Magnetic Imager instrument on the Solar Dynamics Observatory satellite. The six major flares occurred near the main magnetic neutral lines of four active regions, NOAA 11158, 11166, 11283, and 11429. During all six flares the neutral-line field vectors became stronger and more horizontal, in each case almost entirely due to strengthening of the horizontal field components parallel to the neutral line. In all six cases the neutral-line pre-flare fields were more vertical than the reference potential fields, and collapsed abruptly and permanently closer to potential-field tilt angles during every flare, implying that the relaxation of magnetic stress associated with non-potential tilt angles plays a major role during major flares. The shear angle with respect to the reference potential field did not show such a pattern, demonstrating that flare processes do not generally relieve magnetic stresses associated with photospheric magnetic shear. The horizontal fields became significantly and permanently more aligned with the neutral line during the four largest flares, suggesting that the collapsing field is on average more aligned with the neutral line than the pre-flare neutral-line field. The vertical Lorentz force had a large, abrupt, permanent downward change during each of the flares, consistent with loop collapse. The horizontal Lorentz force changes acted mostly parallel to the neutral line in opposite directions on each side, a signature of the fields contracting during the flare, pulling the two sides of the neutral line toward each other. The greater effect of the flares on field tilt than on shear may be explained by photospheric line-tying.

Petrie, G. J. D. [National Solar Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States)

2012-11-01

192

Changes in the Amplitude and Phase of the Annual Cycle: quantifying from surface wind series in China  

NASA Astrophysics Data System (ADS)

Climate change is not only reflected in the changes in annual means of climate variables but also in the changes in their annual cycles (seasonality), especially in the regions outside the tropics. Changes in the timing of seasons, especially the wind season, have gained much attention worldwide in recent decade or so. We introduce long-range correlated surrogate data to Ensemble Empirical Mode Decomposition method, which represent the statistic characteristics of data better than white noise. The new method we named Ensemble Empirical Mode Decomposition with Long-range Correlated noise (EEMD-LRC) and applied to 600 station wind speed records. This new method is applied to investigate the trend in the amplitude of the annual cycle of China's daily mean surface wind speed for the period 1971-2005. The amplitude of seasonal variation decrease significantly in the past half century over China, which can be well explained by Annual Cycle component from EEMD-LRC. Furthermore, the phase change of annual cycle lead to strongly shorten of wind season in spring, and corresponding with strong windy day frequency change over Northern China.

Feng, Tao

2013-04-01

193

Climate change, offshore wind power, and the coastal zone management act  

Microsoft Academic Search

Due to its low carbon footprint, wind power is an energy source of growing importance. Although issues with the intermittent nature of the wind resource may limit develop in some terrestrial areas, the marine environment has proven itself ideal, due to the relative consistency of wind flow. Regardless of the final structure created by MMS in the implementation of the

2008-01-01

194

The solar wind interactions with lunar magnetic anomalies: A case study of the Chang'E-2 plasma data near the Serenitatis antipode  

NASA Astrophysics Data System (ADS)

We present the first and preliminary results on the near-Moon plasma environment, based on the spectrogram data obtained with the Solar Wind Ion Detector (SWID) onboard Chang'E-2 from 4 lunar orbits on 10-11 Oct 2010. These orbits, at a constant altitude of ~100 km, approach gradually the Lunar Magnetic Anomaly (LMA) at the Serenitatis antipode. The data reveal tentatively a region with decrement in proton density and enhancement in temperature. The near coincidence of this region with the Serenitatis antipode probably suggests the presence of a mini-magnetosphere associated with the LMA, which effectively shields and heats the incident Solar Wind (SW) protons.

Wang, X.-Q.; Cui, J.; Wang, X.-D.; Liu, J.-J.; Zhang, H.-B.; Zuo, W.; Su, Y.; Wen, W.-B.; Rème, H.; Dandouras, I.; Aoustin, C.; Li, C.-L.; Ouyang, Z.-Y.

2012-09-01

195

The Solar Wind interactions with Lunar Magnetic Anomalies: A case study of the Chang'E-2 plasma data near the Serenitatis antipode  

NASA Astrophysics Data System (ADS)

In this paper, we present the first and preliminary results on the near-Moon plasma environment, based on the spectrogram data obtained with the Solar Wind Ion Detector (SWID) onboard Chang'E-2 from four lunar orbits on 10-11 Oct 2010. These orbits, at a constant altitude of ˜100 km, approach gradually the Lunar Magnetic Anomaly (LMA) at the Serenitatis antipode. The data reveal tentatively a region with decrement in proton density and enhancement in temperature. The near coincidence of this region with the Serenitatis antipode probably suggests the presence of a minimagnetosphere associated with the LMA, which effectively shields and heats the incident Solar Wind (SW) protons.

Wang, X.-Q.; Cui, J.; Wang, X.-D.; Liu, J.-J.; Zhang, H.-B.; Zuo, W.; Su, Y.; Wen, W.-B.; Rème, H.; Dandouras, I.; Aoustin, C.; Wang, M.; Tan, X.; Shen, J.; Wang, F.; Fu, Q.; Li, C.-L.; Ouyang, Z.-Y.

2012-12-01

196

Efficacy of child abuse and neglect prevention messages in the Florida Winds of Change campaign.  

PubMed

Public awareness campaigns have been included in universal, communitywide, and programmatic approaches aimed at preventing child abuse and neglect. More evaluation of campaign effects is needed to identify their place on the continuum of evidence-based programs. This article reports on an efficacy study of the Florida Winds of Change campaign using a randomized experimental design. Investigators conducted an online survey of a web-based panel of Florida residents with children 18 years of age or younger living in the home. Six outcomes were measured at baseline and a 30-day follow-up. Three outcomes referred to knowledge of child development, child disciplinary techniques, and community resources for parents. Prevention attitudes or beliefs, motivation, and action were also assessed. Respondents were exposed to three public service announcements and a selection of parent resource material. Logistic regression models revealed that exposure to campaign messages was associated with significant increases in all but one of the campaign outcomes. PMID:22206348

Evans, W Douglas; Falconer, Mary Kay; Khan, Munziba; Ferris, Christie

2011-12-29

197

Risk maps for range expansion of the Lyme disease vector, Ixodes scapularis, in Canada now and with climate change  

PubMed Central

Background Lyme disease is the commonest vector-borne zoonosis in the temperate world, and an emerging infectious disease in Canada due to expansion of the geographic range of the tick vector Ixodes scapularis. Studies suggest that climate change will accelerate Lyme disease emergence by enhancing climatic suitability for I. scapularis. Risk maps will help to meet the public health challenge of Lyme disease by allowing targeting of surveillance and intervention activities. Results A risk map for possible Lyme endemicity was created using a simple risk algorithm for occurrence of I. scapularis populations. The algorithm was calculated for each census sub-division in central and eastern Canada from interpolated output of a temperature-driven simulation model of I. scapularis populations and an index of tick immigration. The latter was calculated from estimates of tick dispersion distances by migratory birds and recent knowledge of the current geographic range of endemic I. scapularis populations. The index of tick immigration closely predicted passive surveillance data on I. scapularis occurrence, and the risk algorithm was a significant predictor of the occurrence of I. scapularis populations in a prospective field study. Risk maps for I. scapularis occurrence in Canada under future projected climate (in the 2020s, 2050s and 2080s) were produced using temperature output from the Canadian Coupled Global Climate Model 2 with greenhouse gas emission scenario enforcing 'A2' of the Intergovernmental Panel on Climate Change. Conclusion We have prepared risk maps for the occurrence of I. scapularis in eastern and central Canada under current and future projected climate. Validation of the risk maps provides some confidence that they provide a useful first step in predicting the occurrence of I. scapularis populations, and directing public health objectives in minimizing risk from Lyme disease. Further field studies are needed, however, to continue validation and refinement of the risk maps.

Ogden, Nicholas H; St-Onge, Laurie; Barker, Ian K; Brazeau, Stephanie; Bigras-Poulin, Michel; Charron, Dominique F; Francis, Charles M; Heagy, Audrey; Lindsay, L Robbin; Maarouf, Abdel; Michel, Pascal; Milord, Francois; O'Callaghan, Christopher J; Trudel, Louise; Thompson, R Alex

2008-01-01

198

Cytoplasmic Calcium Increases in Response to Changes in the Gravity Vector in Hypocotyls and Petioles of Arabidopsis Seedlings1  

PubMed Central

Plants respond to a large variety of environmental signals, including changes in the gravity vector (gravistimulation). In Arabidopsis (Arabidopsis thaliana) seedlings, gravistimulation is known to increase the cytoplasmic free calcium concentration ([Ca2+]c). However, organs responsible for the [Ca2+]c increase and the underlying cellular/molecular mechanisms remain to be solved. In this study, using Arabidopsis seedlings expressing apoaequorin, a Ca2+-sensitive luminescent protein in combination with an ultrasensitive photon counting camera, we clarified the organs where [Ca2+]c increases in response to gravistimulation and characterized the physiological and pharmacological properties of the [Ca2+]c increase. When the seedlings were gravistimulated by turning 180°, they showed a transient biphasic [Ca2+]c increase in their hypocotyls and petioles. The second peak of the [Ca2+]c increase depended on the angle but not the speed of rotation, whereas the initial peak showed diametrically opposite characters. This suggests that the second [Ca2+]c increase is specific for changes in the gravity vector. The potential mechanosensitive Ca2+-permeable channel (MSCC) inhibitors Gd3+ and La3+, the Ca2+ chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N?,N?-tetraacetic acid (BAPTA), and the endomembrane Ca2+-permeable channel inhibitor ruthenium red suppressed the second [Ca2+]c increase, suggesting that it arises from Ca2+ influx via putative MSCCs in the plasma membrane and Ca2+ release from intracellular Ca2+ stores. Moreover, the second [Ca2+]c increase was attenuated by actin-disrupting drugs cytochalasin B and latrunculin B but not by microtubule-disrupting drugs oryzalin and nocodazole, implying that actin filaments are partially involved in the hypothetical activation of Ca2+-permeable channels. These results suggest that the second [Ca2+]c increase via MSCCs is a gravity response in the hypocotyl and petiole of Arabidopsis seedlings.

Toyota, Masatsugu; Furuichi, Takuya; Tatsumi, Hitoshi; Sokabe, Masahiro

2008-01-01

199

Using incoherent scatter radar to investigate the neutral wind long-term trend over Arecibo  

Microsoft Academic Search

Thermospheric neutral winds can be the most important driver when modeling ionospheric densities and temperatures. Several papers in this special edition show interesting features of the neutral winds behavior during the last 30 years at the Arecibo Observatory (18.3°N, 66.75°W ~28.25° dip latitude) using Fabry-Perot Interferometer (FPI) data. A neutral wind vector that changes its direction, becoming more dominantly eastward

P. T. Santos; C. G. M. Brum; C. A. Tepley; N. Aponte; S. A. González; E. Robles

2011-01-01

200

Influence on the hydrodynamic performance of a variable vector propeller of different rules of pitch angle change  

NASA Astrophysics Data System (ADS)

To design a more effective blade pitch adjustment mechanism, research was done on changes to the hydrodynamic characteristics of VVPs (Variable Vector Propeller) caused by different rules for changing pitch angle. A mathematical method for predicting the hydrodynamic characteristics of a VVP under unsteady conditions is presented based on the panel method. Mathematical models for evaluation based on potential flow theory and the Green theorem are also presented. The hydrodynamic characteristics are numerically predicted. To avoid gaps between panels, hyperboloidal quadrilateral panels were used. The pressure Kutta condition on the trailing edge of the VVP blade was satisfied by the Newton-Raphson iterative procedure. The influence coefficients of the panels were calculated by Morino’s analytical formulations to improve numerical calculation speed, and the method developed by Yanagizawa was used to eliminate the point singularity on derivation calculus while determining the velocities on propeller surfaces. The calculation results show that it’s best for the hydrodynamic characteristics of the VVP that pitch angle changes follow the sine rule.

Chang, Xin; Zou, Jing-Xiang; Huang, Sheng; Guo, Chun-Yu

2007-12-01

201

Feline leukemia virus integrase and capsid packaging functions do not change the insertion profile of standard Moloney retroviral vectors.  

PubMed

Adverse events linked to perturbations of cellular genes by vector insertion reported in gene therapy trials and animal models have prompted attempts to better understand the mechanisms directing viral vector integration. The integration profiles of vectors based on MLV, ASLV, SIV and HIV have all been shown to be non-random, and novel vectors with a safer integration pattern have been sought. Recently, we developed a producer cell line called CatPac that packages standard MoMLV vectors with feline leukemia virus (FeLV) gag, pol and env gene products. We now report the integration profile of this vector, asking if the FeLV integrase and capsid proteins could modify the MoMLV integration profile, potentially resulting in a less genotoxic pattern. We transduced rhesus macaque CD34+ hematopoietic progenitor cells with CatPac or standard MoMLV vectors, and determined their integration profile by LAM-PCR. We obtained 184 and 175 unique integration sites (ISs) respectively for CatPac and standard MoMLV vectors, and these were compared with 10 000 in silico-generated random IS. The integration profile for CatPac vector was similar to MoMLV and equally non-random, with a propensity for integration near transcription start sites and in highly dense gene regions. We found an IS for CatPac vector localized 715 nucleotides upstream of LMO-2, the gene involved in the acute lymphoblastic leukemia developed by X-SCID patients treated by gene therapy using MoMLV vectors. In conclusion, we found that replacement of MoMLV env, gag and pol gene products with FeLV did not alter the basic integration profile. Thus, there appears to be no safety advantage for this packaging system. However, considering the stability and efficacy of CatPac vectors, further development is warranted, using potentially safer vector backbones, for instance those with a SIN configuration. PMID:20237508

Métais, J-Y; Topp, S; Doty, R T; Borate, B; Nguyen, A-D; Wolfsberg, T G; Abkowitz, J L; Dunbar, C E

2010-03-18

202

Large and sharp changes of solar wind dynamic pressure and disturbances of the magnetospheric magnetic field at geosynchronous orbit caused by these variations  

Microsoft Academic Search

The large and sharp changes of solar wind dynamic pressure, found from the INTERBALL-1 satellite and WIND spacecraft data, are compared with simultaneous magnetic field disturbances in the magnetosphere measured by geosynchronous\\u000a GOES-8, GOES-9, and GOES-10 satellites. For this purpose, about 200 events in the solar wind, associated with sharp changes of the dynamic pressure,\\u000a were selected from the INTERBALL-1

N. L. Borodkova; G. N. Zastenker; M. O. Ryazantseva; J. Richardson

2006-01-01

203

Econometric analysis of the changing effects in wind strength and significant wave height on the probability of casualty in shipping  

Microsoft Academic Search

This study uses econometric models to measure the effect of significant wave height and wind strength on the probability of casualty and tests whether these effects changed. While both effects are in particular relevant for stability and strength calculations of vessels, it is also helpful for the development of ship construction standards in general to counteract increased risk resulting from

Sabine Knapp; Shashi Kumar; Yuri Sakurada; Jiajun Shen

2011-01-01

204

Wind power or uranium mine: Appraisal of two energy-related environmental changes in a local context  

Microsoft Academic Search

This study explores factors associated with the individual's appraisal of anticipated environmental changes caused by energy production facilities. The study took place in a Swedish village where exploratory drilling, that could eventually lead to a uranium mine, was being conducted at the same time as a wind farm was approved. Results from the survey, which included the total population, were

Eja Pedersen; Maria Johansson

2012-01-01

205

Glyphs for Visualizing Uncertainty in Vector Fields  

Microsoft Academic Search

Environmental data have inherent uncertainty which is often ignored in visualization. Meteorological stations and doppler radars, including their time series averages, have a wealth of uncertainty information that traditional vector visualization methods such as meteorological wind barbs and arrow glyphs simply ignore. We have developed a new vector glyph to visualize uncertainty in winds and ocean currents. Our approach is

Craig M. Wittenbrink; Alex Pang; Suresh K. Lodha

1996-01-01

206

Transient and Steady-State Simulation Study of Decoupled d-q Vector Control in PWM Converter of Variable Speed Wind Turbines  

Microsoft Academic Search

Variable-speed wind turbines are attractive to the high performance and are commonly used by the wind turbine industry today. They are based on variable-speed operation with pitch control using either a direct driven synchronous generator (without gearbox) or a doubly-fed induction generator. For both, there is an AC\\/DC\\/AC PWM converter that is used for wind turbine control and grid interface.

Shuhui LiandTimothy; T. A. Haskew

2007-01-01

207

Animal behavioral adaptation to changing landscapes: spring-staging geese habituate to wind farms  

Microsoft Academic Search

Wind farms are positioned in open landscapes and may cause loss of wildlife habitat due to disturbance, fragmentation, and\\u000a infrastructure development. Especially flocking geese, swans, ducks and waders are regarded as vulnerable to wind farm development.\\u000a We compared past and current displacement effects of two onshore wind farms and a line of land-based turbines on spring-staging\\u000a pink-footed geese (Anser brachyrhynchus) to

Jesper Madsen; David Boertmann

2008-01-01

208

Pharmacological analysis of calcium transients in response to gravity vector change in Arabidopsis hypocotyls and petioles.  

NASA Astrophysics Data System (ADS)

Plants regulate their growth and morphology in response to gravity field known as gravitropism in general In the process of gravitropism gravity sensing will form the critical earliest event which is supposed to take place in specialized cells statocytes such as columella cells and shoot endodermal cells Although gravistimulation is assumed to be converted into certain intracellular signals the underlying transduction mechanisms have hardly been explored One of the potential candidates for the intracellular signals is an increase in the cytoplasmic free calcium concentration Ca 2 c Here we measured Ca 2 c changes induced by gravistimulation in seedlings of Arabidopsis thaliana expressing aequorin as a calcium reporter When a plate of seedlings was turned through 180 r Ca 2 c transiently increased within 50 s and decayed exponentially with a time constant of ca 60 s The amplitude of the Ca 2 c increase was independent of the angular velocity of the rotation The Ca 2 c increase was reversibly blocked by extracellularly applied potential mechanosensitive channel blockers La 3 Gd 3 or a Ca 2 chelator BAPTA indicating that it arose from Ca 2 -influx via Ca 2 -permeable channel s on the plasma membrane Furthermore the Ca 2 c increase was attenuated by actin-disrupting drugs latrunculin B cytochalasin B but not by microtuble-disrupting drugs oryzalin nocodazole indicating that the activation of

Toyota, M.; Furuichi, T.; Tatsumi, H.; Sokabe, M.

209

Control strategies for energy recovery from a flywheel using a vector controlled induction machine  

Microsoft Academic Search

This paper presents a novel control strategy for power smoothing in wind energy applications, especially those feeding a stand-alone load. The system is based on a vector controlled induction machine driving a flywheel and addresses the problem of regulating the DC-link system voltage against both input power surges\\/sags from a wind turbine or sudden changes in load demand. The control

R. Cardenas; R. Pena; G. Asher; J. Clare

2000-01-01

210

Overwinter Changes in Wind Erodibility of Clay Loam Soils in Southern Alberta  

SciTech Connect

Soil dry aggregate size distribution (DASD) and surface roughness are important factors affecting wind erodibility. This study monitored overwinter changes in DASD and surface roughness and identified relationships with climatic variables in the chinook-dominated region of southern Alberta. A different site was monitored in each of three winters (18 Sept. 1992 to 12 May 1993; 26 Oct. 1993 to 29 Apr. 1994; 30 Aug. 1994 to 24 May 1995) on Dark Brown Chernozemic clay loams (fine-loamy, mixed, Typic Haploborolls). The DASD was expressed as geometric mean diameter (GMD) and wind erodible fraction (EF). The GMD ranged from 1.88 to 0.08 mm in 1992-1993, from 9.05 to 1.17 mm in 1993-1994, and from 4.71 to 0.80 mm in 1994-1995. The EF range from 38.9 to 74.0% in 1992-1993, from 12.6 to 43.7% in 1993-1994, and 31.3 to 55.% in 1994-1995. Surface roughness was measured parallel (Cpar) to tillage direction on two of the sites. Using the chain method, Cper ranged from 15.1 to 3.7% in 1993-199 4 and from 14.4 to 3.3% in 1994-1995. Regression analysis with time revealed significant exponential decay for GMD (R2= 0.57 in 1992-1993, 0.97 in 1993-1994, and 0.78 in 1994-1995) and Cpar (R2= 0.98 in 1993-1994, 0.91 in 1994-1995) and a positive linear fit for EF (R2= 0.57 in 1992-1993, 0.91 in 1993-1994, and 0.62 in 1994-1995). Three overwinter periods, differentiated by the timing and form of precipitation and designated as''fall rain/snow'',''winter snow'', and''spring snow/rain'', were used to assess the changes in EF using cumulative freeze-thaw cycles, precipitation, and snow cover

Bullock, M S. (The Amalgamated Sugar Company); Larney, F. J. (Agriculture and Agri-Food Canada); Izaurralde, R Cesar C. (BATTELLE (PACIFIC NW LAB)); Feng, Y (University of Alberta)

2001-03-21

211

Evaluation of QuikSCAT wind vector performance with respect to field measurements for the Bulgarian part of the Black Sea  

Microsoft Academic Search

Winds over the ocean play an important role in meteorology, oceanography and climatology. They affect air-sea variations in heat, humidity, gases and particles, regulating the crucial relation between the ocean and the atmosphere that establishes and supports the climate on regional and global scale. Therefore, the knowledge of wind fields over the oceans is essential for global weather forecast purposes.

Violeta Slabakova; Nataliya Andreeva; Petya Eftimova; Roumen Nedkov

2009-01-01

212

Polar cap convection and PC index during sudden changes in solar wind dynamic pressure  

Microsoft Academic Search

The polar cap (PC) index derived from polar magnetic variations is primarily a measure of the intensity of the transpolar ionospheric currents generated by the solar wind interaction with the Earth's magnetosphere. We have examined the influence of the solar wind dynamic pressure on the PC index in cases of global sudden impulses (SI) or storm sudden commencement (SSC) magnetic

P. Stauning; O. A. Troshichev

2008-01-01

213

Mars Pathfinder landing site: Evidence for a change in wind regime from lander and orbiter data  

Microsoft Academic Search

Surface features related to the wind are observed in the vicinity of the Mars Pathfinder (MPF) landing site data from the lander and in data from orbit by the Viking Orbiter and Mars Global Surveyor missions. Features seen from the surface include wind tails associated with small rocks, barchanoid duneforms, ripplelike patterns, and ventifact flutes cut into some rocks. Features

Ronald Greeley; Michael D. Kraft; Ruslan O. Kuzmin; Nathan T. Bridges

2000-01-01

214

Analysis of filament wound composite structures considering the change of winding angles through the thickness direction  

Microsoft Academic Search

In this study, filament winding patterns were calculated using a semi-geodesic fiber path equation for an arbitrary surface. Because the fiber path depends on the surface where fibers are wound, the winding angle varies in the longitudinal and thickness directions of a wound structure. The fiber angle difference through the thickness was calculated for several design parameters, such as helical

Jae-Sung Park; Chang-Sun Hong; Chun-Gon Kim; Cheol-Ung Kim

2002-01-01

215

Assessment and Analysis of QuikSCAT Vector Wind Products for the Gulf of Mexico: A Long-Term and Hurricane Analysis  

PubMed Central

The northern Gulf of Mexico is a region that has been frequently impacted in recent years by natural disasters such as hurricanes. The use of remote sensing data such as winds from NASA's QuikSCAT satellite sensor would be useful for emergency preparedness during such events. In this study, the performance of QuikSCAT products, including JPL's latest Level 2B (L2B) 12.5 km swath winds, were evaluated with respect to buoy-measured winds in the Gulf of Mexico for the period January 2005 to February 2007. Regression analyses indicated better accuracy of QuikSCAT's L2B DIRTH, 12.5 km than the Level 3 (L3), 25 km wind product. QuikSCAT wind data were compared directly with buoy data keeping a maximum time interval of 20 min and spatial interval of 0.1° (?10 km). R2 values for moderate wind speeds were 0.88 and 0.93 for L2B, and 0.75 and 0.89 for L3 for speed and direction, respectively. QuikSCAT wind comparisons for buoys located offshore were better than those located near the coast. Hurricanes that took place during 2002-06 were studied individually to obtain regressions of QuikSCAT versus buoys for those events. Results show QuikSCAT's L2B DIRTH wind product compared well with buoys during hurricanes up to the limit of buoy measurements. Comparisons with the National Hurricane Center (NHC) best track analyses indicated QuikSCAT winds to be lower than those obtained by NHC, possibly due to rain contamination, while buoy measurements appeared to be constrained at high wind speeds. This study has confirmed good agreement of the new QuikSCAT L2B product with buoy measurements and further suggests its potential use during extreme weather conditions in the Gulf of Mexico.

Sharma, Neha; D'Sa, Eurico

2008-01-01

216

The ionospheric signatures of flux transfer events and solar wind dynamic pressure changes  

SciTech Connect

The generation of flow and current vortices in the dayside auroral ionosphere has been predicted for two processes occurring at the dayside magnetopause. The first of these mechanisms is time-dependent magnetic reconnection, in flux transfer events (FTEs); the second is the action of solar wind dynamic pressure changes. The ionospheric flow signature of an FTE should be a twin vortex, with the mean flow velocity in the central regon of the pattern equal ot the velocity of the pattern as a whole. On the other hand, a pulse of enhanced or reduced dynamic pressure is also expected to produce a twin vortex, but with the central plasma flow being generally different in speed from, and almost orthogonal to, the motion of the whole pattern. In this paper, the authors make use of this distinction to discuss recent observations of vortical flow patterns in the dayside auroral ionosphere in terms of one or other of the proposed mechanisms. They conclude that some of the observatons reported are consistent only with the predicted signature of FTEs. They then evaluate the dimensions of the open flux tubes required to explain some recent simultaneous radar and auroral observatons and infer that they are typically 300 km in north-south extent but up to 2,000 km in longitudinal extent (i.e., roughly 5 hours of MLT). Hence these observations suggest that recent theories of FTEs which invoke time-varying reconnecton at an elongated neutral line may be correct.

Lockwood, M. (Rutherford Appleton Lab., Chilton (England) Imperial College, London (England)); Cowley, S.W.H. (Imperial College, London (England)); Sandholt, P.E. (Univ. of Oslo (Norway)); Lepping, R.P. (Goddard Space Flight Center, Greenbelt, MD (United States))

1990-10-01

217

Vector Addition  

NSDL National Science Digital Library

This 2D applet simulates vector addition geometrically. The user selects the angle and magnitude of two vectors, which are then added together by the applet. The resultant vector and the values of its magnitude and angle, as well as the values of the x and y components of all three vectors, are calculated and displayed.

Duffy, Andrew

2004-11-28

218

Vector Calculator  

NSDL National Science Digital Library

A simple Java applet enabling users to add two two-dimensional vectors. The user can choose the two vectors by clicking on a grid. The components, magnitude, and direction are immediately shown. Once the two vectors are chosen, a press of a button shows the vector sum, its components, its magnitude and its direction.

Gea-Banacloche

2009-08-10

219

VAX vector architecture  

Microsoft Academic Search

The VAX architecture has been extended to include an integrated, register-based vector processor. This extension allows both high-end and low-end implementations and can be supported with only small changes by VAX\\/VMS and VAX\\/ULTRIX operating systems. The extension is effectively exploited by the new vectorizing capabilities of VAX Fortran. Features of the VAX vector architecture and the design decisions which make

Dileep Bhandarkar; Richard Brunner

1990-01-01

220

VAX vector architecture  

Microsoft Academic Search

The VAX Architecture has been extended to include an integrated, register-based vector processor. This extension allows both high-end and low-end implementations and can be supported with only small changes by VAX\\/VMS and VAX\\/ULTRIX operating systems. The extension is effectively exploited by the new vectorizing capabilities of VAX FORTRAN. Features of the VAX Vector Architecture and the design decisions which make

Dileep Bhandarkar; Richard Brunner

1990-01-01

221

Role of CO2 and Southern Ocean winds in glacial abrupt climate change  

NASA Astrophysics Data System (ADS)

The study of Greenland ice cores revealed two decades ago the abrupt character of glacial millennial-scale climate variability. Several triggering mechanisms have been proposed and confronted against growing proxy-data evidence. Although the implication of North Atlantic deep water (NADW) formation reorganisations in glacial abrupt climate change seems robust nowadays, the final cause of these reorganisations remains unclear. Here, the role of CO2 and Southern Ocean winds is investigated using a coupled model of intermediate complexity in an experimental setup designed such that the climate system resides close to a threshold found in previous studies. An initial abrupt surface air temperature (SAT) increase over the North Atlantic by 4 K in less than a decade, followed by a more gradual warming greater than 10 K on centennial timescales, is simulated in response to increasing atmospheric CO2 levels and/or enhancing southern westerlies. The simulated peak warming shows a similar pattern and amplitude over Greenland as registered in ice core records of Dansgaard-Oeschger (D/O) events. This is accompanied by a strong Atlantic meridional overturning circulation (AMOC) intensification. The AMOC strengthening is found to be caused by a northward shift of NADW formation sites into the Nordic Seas as a result of a northward retreat of the sea-ice front in response to higher temperatures. This leads to enhanced heat loss to the atmosphere as well as reduced freshwater fluxes via reduced sea-ice import into the region. In this way, a new mechanism that is consistent with proxy data is identified by which abrupt climate change can be promoted.

Banderas, R.; Álvarez-Solas, J.; Montoya, M.

2012-06-01

222

Evidence of long-term change in zonal wind in the tropical lower mesosphere: Observations and model simulations  

NASA Astrophysics Data System (ADS)

In recent years, the mesosphere (50 to 85-100 km) has evoked great scientific interest as long-term changes due to global warming can be clearly captured due to the large perturbation amplitudes at these altitudes. In the present study, zonal wind observations between 70 and 80 km over the Indian region provided by rocketsonde (1977-1991), HRDI/UARS (1991-1999), and MST radar (1995-2010) are used to construct a long-term data set from 1977 to 2010. Using this unprecedented data set, a decreasing trend of 2 m/s/yr is found, changing from strong eastward winds during the 1970s to weak westward winds in recent years. On the other hand, between 80 and 98 km using medium frequency radar observations during 1993-2009, no perceptible trend is found. Simulations of NCAR TIME-GCM also showed a similar change in the circulation when CO2 in the atmosphere is doubled, suggesting role of anthropogenic changes in the dynamics of the mesosphere.

Venkat Ratnam, M.; Kishore Kumar, G.; Venkateswara Rao, N.; Krishna Murthy, B. V.; LašTovi?Ka, Jan; Qian, Liying

2013-01-01

223

Impact of Global Climate Changes on the Wind Power Density in Brazil  

NASA Astrophysics Data System (ADS)

The potential onshore wind power resources in Brazil could reach more than 145,000 MW. Brazil's wind energy production has risen up from 22 MW in 2003 to 602 MW in 2009 thanks to the government policy and incentives to encourage the use of wind power and other renewable sources of energy. An additional 256.4 MW is now under construction and should start the op-eration at the end of 2010. Recently 71 additional projects have been approved as a result of the first wind-only bidding round for energy supply in Brazil of December 2009. The contracts, to-taling 1800MW, will start in July 2012 with a supply period of 20 years. Developing wind power in Brazil will help the country to meet its strategic objectives of enhancing energy security and reducing the country's energy-related greenhouse gas emissions. In spite of this, the long-term growth of the national wind capacity depends not only on a more competitive price for this en-ergy source (today at US84, 8M W h)butalsoonthesustainabledomesticdevelopmentof thistechnology.F urth controldatascreeningprocesstoselectvalidclimatologicaltimeseriesf ollowedbytheKendalltrendtestat95

Martins, Fernando; Pereira, Enio; Pes, Marcelo; Segundo, Eliude; Lyra, Andr

224

Wind turbine  

Microsoft Academic Search

A wind turbine of the type having an airfoil blade mounted on a flexible beam and a pitch governor which selectively, torsionally twists the flexible beam in response to wind turbine speed thereby setting blade pitch, is provided with a limiter which restricts unwanted pitch change at operating speeds due to torsional creep of the flexible beam. The limiter allows

1982-01-01

225

Wind turbine  

Microsoft Academic Search

A wind turbine of the type having an airfoil blade (15) mounted on a flexible beam (20) and a pitch governor (55) which selectively, torsionally twists the flexible beam in response to wind turbine speed thereby setting blade pitch, is provided with a limiter (85) which restricts unwanted pitch change at operating speeds due to torsional creep of the flexible

Marvin C

1982-01-01

226

Changes in the onset and intensity of wind-driven upwelling and downwelling along the North American Pacific coast  

NASA Astrophysics Data System (ADS)

The timing, duration, and intensity of wind-driven upwelling and downwelling along the North American Pacific coast play an integral role in coastal circulation and basinwide ecosystem composition. It has been suggested that global warming will cause changes in these winds. Here we develop a new set of objective criteria to unambiguously determine the onset, duration, and intensity of upwelling and downwelling seasons due to local wind forcing. We use these criteria to examine and better characterize temporal trends in wind-driven coastal currents over the previous 60 years and relate them to global warming and large-scale climate oscillations in the coastal ocean between northern California and Vancouver Island (37°N and 51°N). We find an exceptionally variable onset of upwelling at all locations. Some significant temporal trends are found in summer onset and upwelling intensity time series near the Juan de Fuca Strait and off the coast of Oregon. Positive phases of the Pacific Decadal Oscillation are correlated to later and shorter upwelling seasons with weaker upwelling. Warm phases of the El Niño Southern Oscillation are associated with a later onset of summer upwelling south of Oregon and with more intense downwelling throughout the study area. Our analysis identifies strong interannual to interdecadal variability, and emphasizes the importance of time series length when isolating physical temporal trends influenced by large-scale oscillatory behavior of the climate.

Bylhouwer, Brian; Ianson, Debby; Kohfeld, Karen

2013-05-01

227

Kinetic Monte Carlo studies of the effects of Burgers Vector Changes on the Reaction Kinetics of One-Dimensionally Gliding Interstitial Clusters  

SciTech Connect

Kinetic Monte Carlo simulations of one-dimensionally diffusing interstitial clusters (dislocation loops) are used to gain insight into their role in microstructure evolution under irradiation. The simulations investigate the changes in reaction kinetics of these defects as a function of changes in the Burgers vector and variation in the size and density of randomly or periodically distributed sinks. In this paper we report on several kinetic Monte Carlo studies intended to elucidate the effects of mixed 1-D/3-D migration relative to pure 3-D and pure 1-D migration. We have investigated the effects of variation of the average distance traveled between Burgers vector changes (L) on the absorption of individual defects into absorbers of varying size and varying concentration, as well as the effects of variatioin in (L) on the time dependence of absorption of a collection of defects into an array of absorbers. Significant effects of Burgers vector changes on the reaction kinetics of the diffusing interstitial clusters are clearly demonstrated. Even when (L) is larger relative to the size and spacing of microstructural features, significant effects of mixed 1-D/3-D migration on reaction kinetics are evident.

Heinisch, Howard L.; Singh, Bachu N.; Golubov, Stanislav I.

2000-01-01

228

Climate change projected fire weather sensitivity: CaliforniaSanta Ana wind occurrence  

SciTech Connect

A new methodbased on global climate model pressuregradients was developed for identifying coastal high-wind fire weatherconditions, such as the Santa Ana Occurrence (SAO). Application of thismethod for determining southern California Santa Ana wind occurrenceresulted in a good correlation between derived large-scale SAOs andobserved offshore winds during periods of low humidity. The projectedchange in the number of SAOs was analyzed using two global climatemodels, one a low temperature sensitivity and the other amiddle-temperature sensitivity, both forced with low and high emissionscenarios, for three future time periods. This initial analysis showsconsistent shifts in SAO events from earlier (September-October) to later(November-December) in the season, suggesting that SAOs may significantlyincrease the extent of California coastal areas burned by wildfires, lossof life, and property.

Miller, Norman L.; Schlegel, Nicole J.

2006-01-01

229

Wind Stress Curl and Wind Stress Divergence Biases from Rain Effects on QSCAT Surface Wind Retrievals  

Microsoft Academic Search

Surface vector wind datasets from scatterometers provide essential high-resolution surface forcing information for analyses and models of global atmosphere-ocean processes affecting weather and climate. The importance of realistic amplitude, high-wavenumber, surface wind forcing from scatterometer data has been demonstrated in a variety of ocean modeling applications. However, the radar backscatter signal from which surface vector wind estimates are retrieved is

Ralph F. Milliff; Jan Morzel; Dudley B. Chelton; Michael H. Freilich

2004-01-01

230

DC bus voltage build up and control in stand-alone wind energy conversion system using direct vector control of SCIM  

Microsoft Academic Search

This paper presents the start up and operation of a stand-alone wind energy conversion system (WECS) using a squirrel cage induction machine (SCIM). The proposed scheme obviates the use of either excitation capacitor or batteries in DC bus. The DC bus comprising of a combination of normal electrolytic capacitor and few super capacitors, is interfaced with the SCIM through a

Samir Hazra; Partha Sarathi Sensarma

2008-01-01

231

Analysis of Unit-Level Changes in Operations with Increased SPP Wind from EPRI/LCG Balancing Study  

SciTech Connect

Wind power development in the United States is outpacing previous estimates for many regions, particularly those with good wind resources. The pace of wind power deployment may soon outstrip regional capabilities to provide transmission and integration services to achieve the most economic power system operation. Conversely, regions such as the Southeastern United States do not have good wind resources and will have difficulty meeting proposed federal Renewable Portfolio Standards with local supply. There is a growing need to explore innovative solutions for collaborating between regions to achieve the least cost solution for meeting such a renewable energy mandate. The Department of Energy funded the project 'Integrating Midwest Wind Energy into Southeast Electricity Markets' to be led by EPRI in coordination with the main authorities for the regions: SPP, Entergy, TVA, Southern Company and OPC. EPRI utilized several subcontractors for the project including LCG, the developers of the model UPLAN. The study aims to evaluate the operating cost benefits of coordination of scheduling and balancing for Southwest Power Pool (SPP) wind transfers to Southeastern Electric Reliability Council (SERC) Balancing Authorities (BAs). The primary objective of this project is to analyze the benefits of regional cooperation for integrating mid-western wind energy into southeast electricity markets. Scenarios were defined, modeled and investigated to address production variability and uncertainty and the associated balancing of large quantities of wind power in SPP and delivery to energy markets in the southern regions of the SERC. DOE funded Oak Ridge National Laboratory to provide additional support to the project, including a review of results and any side analysis that may provide additional insight. This report is a unit-by-unit analysis of changes in operations due to the different scenarios used in the overall study. It focuses on the change in capacity factors and the number of start-ups required for each unit since those criteria summarize key aspects of plant operations, how often are they called upon and how much do they operate. The primary analysis of the overall project is based on security-constrained unit commitment (SCUC) and economic dispatch (SCED) simulations of the SPP-SERC regions as modeled for the year 2022. The SCUC/SCED models utilized for the project were developed through extensive consultation with the project utility partners, to ensure the various regions and operational practices are represented as best as possible in the model. SPP, Entergy, Oglethorpe Power Company (OPC), Southern Company, and the Tennessee Valley Authority (TVA) actively participated in the project providing input data for the models and review of simulation results and conclusions. While other SERC utility systems are modeled, the listed SERC utilities were explicitly included as active participants in the project due to the size of their load and relative proximity to SPP for importing wind energy.

Hadley, Stanton W [ORNL

2012-01-01

232

Epidemiological impact of vector control. I. Incidence and changes in prevalence and intensity of Onchocerca volvulus infection.  

PubMed

Since 1974, the Onchocerciasis Control Programme (OCP) has been engaged in a large scale attempt to control the savanna species of the vector of onchocerciasis in seven West African countries. The effect of the vector control effort has been measured by epidemiological evaluation. For this purpose 474 villages have been examined by means of skin snip surveys between 1975 and 1983 and of these, 184 have been retained to-date for follow-up surveys which have documented over the years the reduction of the parasite population. The latest results of the epidemiological evaluation clearly demonstrate an outstanding success of the vector control campaign. The parasite has been or is close to being eliminated from the hyperendemic foci of the core area of the Programme. Major improvements have been registered in the reinvaded areas located at the Western and Eastern borders of the Programme. A major improvement has been found along the river Marahoué, the only focus of the intermediate area between the savanna and the forest where at the previous survey, the endemic situation was still similar to the pre-control situation. The exceptions to this gratifying picture are foci along the Dienkoa and Kulpawn rivers, both located in the core area, where transmission has relapsed and several more years of an effective vector control will be needed to eliminate the local parasite population. PMID:2378200

De Sole, G; Remme, J; Dadzie, K Y

1990-01-01

233

Climate change and altitudinal structuring of malaria vectors in south-western Cameroon: their relation to malaria transmission.  

PubMed

An entomological survey was conducted in Cameroon between October 2004 and September 2005, in nine localities targeted for malaria vector control based on adult productivity and variability. Mosquitoes were collected by human-landing catches (HLCs) and pyrethrum spray catches. A total of 12 500 anophelines were collected and dissected: Anopheles gambiae s.l. (56.86%), An. funestus s.l. (32.57%), An. hancocki (9.38%), and An. nili (1.18%). Applying PCR revealed that specimens of the An. funestus group were An. funestus s.s. and An. gambiae complex were mostly An. melas and An. gambiae s.s. of the M and S molecular forms with the M forms being the most predominant. The natural distribution patterns of Anopheles species were largely determined by altitude with some species having unique environmental tolerance limits. A human blood index (HBI) of 99.05% was recorded. Mean probability of daily survival of the malaria vectors was 0.92, with annual mean life expectancy of 21.9 days and the expectation of infective life was long with a mean of 7.4 days. The high survival rates suggest a high vector potential for the species. This information enhances the development of a more focused and informed vector control intervention. PMID:20346477

Tanga, M C; Ngundu, W I; Judith, N; Mbuh, J; Tendongfor, N; Simard, Frédéric; Wanji, S

2010-03-25

234

Hazard of extreme wind gusts to buildings in Australia and its sensitivity to climate change  

Microsoft Academic Search

This paper presents a preliminary study on hazard modeling, estimation, and mapping of extreme wind gusts for consideration of buildings and infrastructure in Australia. Buildings and infrastructure provide essential support for the quality of life and are the founding blocks for social and economic development. Typically the design service life of buildings is around 50 years and that of infrastructure

X. Wang

2009-01-01

235

Atmospheric transparency changes associated with solar wind-induced atmospheric electricity variations  

Microsoft Academic Search

Variations in atmospheric transmission of several percent in nominally clear air are found to accompany solar wind events associated with variations on the day-to-day timescale in the flow of vertical current density (Jz) in the global electric circuit. The effect has been observed only for stations at high latitudes (>55°N). Increases in transmission are present when inferred Jz decreases occurred

V. C. Roldugin; B. A. Tinsley

2004-01-01

236

Investigation of different load changes in wind farm by using FACTS devices  

Microsoft Academic Search

In this study, voltage, active power and reactive power variation of load bus were examined by Flexible AC Transmission Systems devices (FACTS) in grid-connected wind farm. In the system, FACTS devices, Static Synchronous Compensators (STATCOM), Static VAr Compensators (SVC), Static Synchronous Series Compensators (SSSC) and Thyristor Controlled Series Compensators (TCSC), were used. Also, dual feed induction generator (DFIG) was used

M. Kenan Dö?o?lu; Ali Öztürk

237

The Vector Control Strategies for Multiphase Synchronous Motor Drive Systems  

Microsoft Academic Search

This paper studies the multiphase synchronous motor with symmetrical windings and multi-Y-windings displaced in turn by ¿o separately, the mathematical descriptions about which can be concluded as two models: single-windings and multi-windings models in M,T frame. Based on these models, the multiphase vector control strategy and multiphase multi-ply vector control strategy are proposed, so as to achieve the gas-flux-oriented control

Lin Hua; Zou Yunping; He Bi

2006-01-01

238

The gustiness hypothesis: Exploring wind gusts as the primary cause of glacial-interglacial dust flux changes  

NASA Astrophysics Data System (ADS)

During glacial periods of the Late Quaternary, mineral dust emissions from Earth’s dominant source areas were approximately a factor of two higher than interglacial levels. Long-term records from the equator to the poles demonstrate that glacial-interglacial dust flux variations closely track changes in global temperature and ice volume, maintain consistent amplitudes across glacial cycles and show strong coherence between high and low latitudes. This remarkable consistency suggests a global driver of dust flux variations; however, the causes of dust flux changes are poorly understood, limiting interpretation of dust records and assessment of dust’s role in past climate changes. Here we demonstrate that a range of paleorecords, modern observations and model results support wind gustiness as the primary driver of Late Quaternary global dust levels. We suggest that stronger seasonality and steeper meridional temperature gradients during glacial periods and stadials increased the intensity and frequency of high-speed wind gusts, leading to the observed increases in global dust levels. We also test the importance of other proposed drivers of glacial-interglacial dust flux changes, finding that lake level records near dust source areas are inconsistent with the hypothesis that aridity controls dust emissions and identifying evidence negating atmospheric pCO2, sea level and sediment supply as dominant controls.

McGee, D.; Broecker, W. S.; Winckler, G.

2009-12-01

239

Reply [to ``Comment on `Solar wind mechanism suggested for weather and climate change'' by B. Vonnegut and C.B. Moore''  

Microsoft Academic Search

To explain correlations of weather and climate parameters with solar activity via atmospheric electricity requires first, a plausible mechanism (A) relating changes in atmospheric electricity to the relevant solar or solar wind parameters, and second, a plausible mechanism (B) relating changes in the relevant weather and climate parameters to the atmospheric electricity changes.

Brian A. Tinsley

1995-01-01

240

SeaWinds validation with research vessels  

Microsoft Academic Search

The accuracy of vector winds from the SeaWinds scatterometer on the QuikSCAT satellite is assessed, for rain-free conditions, through comparison with observations from research vessels. Several factors that contribute to uncertainty in scatterometer winds are isolated and examined as functions of wind speed. The independent sources of uncertainty considered herein are ambiguity selection, wind speed, wind direction (for correctly selected

Mark A. Bourassa; David M. Legler; James J. O'Brien; Shawn R. Smith

2003-01-01

241

A Spatio-temporal Description of the Abrupt Changes in the Photospheric Magnetic and Lorentz-Force Vectors During the 15 February 2011 X2.2 Flare  

NASA Astrophysics Data System (ADS)

The active region NOAA 11158 produced the first X-class flare of Solar Cycle 24, an X2.2 flare at 01:44 UT on 15 February 2011. The Helioseismic and Magnetic Imager (HMI) instrument on the Solar Dynamics Observatory (SDO) satellite produces 12-minute, 0.5'' pixel-1 vector magnetograms. Here we analyze a series of these data covering a 12-hour interval centered at the time of this flare. We describe the spatial distributions of the photospheric magnetic changes associated with the flare, including the abrupt changes in the field vector, vertical electric current and Lorentz-force vector acting on the solar interior. We also describe these parameters' temporal evolution. The abrupt magnetic changes were concentrated near the neutral line and in two neighboring sunspots. Near the neutral line, the field vectors became stronger and more horizontal during the flare and the shear increased. This was due to an increase in strength of the horizontal field components near the neutral line, most significant in the horizontal component parallel to the neutral line but the perpendicular component also increased in strength. The vertical component did not show a significant, permanent overall change at the neutral line. The increase in field strength at the neutral line was accompanied by a compensating decrease in field strength in the surrounding volume. In the two sunspots near the neutral line the integrated azimuthal field abruptly decreased during the flare but this change was permanent in only one of the spots. There was a large, abrupt, downward vertical Lorentz-force change acting on the solar interior during the flare, consistent with results of past analyses and recent theoretical work. The horizontal Lorentz force acted in opposite directions along each side of neutral line, with the two sunspots at each end subject to abrupt torsional forces relaxing their magnetic twist. These shearing forces were consistent with a contraction of field and decrease of shear near the neutral line, whereas the field itself became more sheared as a result of the field collapsing towards the neutral line from the surrounding volume. The Lorentz forces acting on the atmospheric volume above the photosphere were equal and opposite.

Petrie, G. J. D.

2013-10-01

242

The Effects of Climate Change and Globalization on Mosquito Vectors: Evidence from Jeju Island, South Korea on the Potential for Asian Tiger Mosquito (Aedes albopictus) Influxes and Survival from Vietnam Rather Than Japan  

PubMed Central

Background Climate change affects the survival and transmission of arthropod vectors as well as the development rates of vector-borne pathogens. Increased international travel is also an important factor in the spread of vector-borne diseases (VBDs) such as dengue, West Nile, yellow fever, chikungunya, and malaria. Dengue is the most important vector-borne viral disease. An estimated 2.5 billion people are at risk of infection in the world and there are approximately 50 million dengue infections and an estimated 500,000 individuals are hospitalized with dengue haemorrhagic fever annually. The Asian tiger mosquito (Aedes albopictus) is one of the vectors of dengue virus, and populations already exist on Jeju Island, South Korea. Currently, colder winter temperatures kill off Asian tiger mosquito populations and there is no evidence of the mosquitos being vectors for the dengue virus in this location. However, dengue virus-bearing mosquito vectors can inflow to Jeju Island from endemic area such as Vietnam by increased international travel, and this mosquito vector's survival during colder winter months will likely occur due to the effects of climate change. Methods and Results In this section, we show the geographical distribution of medically important mosquito vectors such as Ae. albopictus, a vector of both dengue and chikungunya viruses; Culex pipiens, a vector of West Nile virus; and Anopheles sinensis, a vector of Plasmodium vivax, within Jeju Island, South Korea. We found a significant association between the mean temperature, amount of precipitation, and density of mosquitoes. The phylogenetic analyses show that an Ae. albopictus, collected in southern area of Jeju Island, was identical to specimens found in Ho Chi Minh, Vietnam, and not Nagasaki, Japan. Conclusion Our results suggest that mosquito vectors or virus-bearing vectors can transmit from epidemic regions of Southeast Asia to Jeju Island and can survive during colder winter months. Therefore, Jeju Island is no longer safe from vector borne diseases (VBDs) due to the effects of globalization and climate change, and we should immediately monitor regional climate change to identify newly emerging VBDs.

Jeong, Ji Yeon; Yoo, Seung Jin; Koh, Young-Sang; Lee, Seogjae; Heo, Sang Taek; Seong, Seung-Yong; Lee, Keun Hwa

2013-01-01

243

Stratospheric volcanic aerosols and changes in air-earth current density at solar wind magnetic sector boundaries as conditions for the Wilcox tropospheric vorticity effect  

SciTech Connect

A correlation between tropospheric dynamics and solar wind magnetic fields that disappeared in the early 1970s reappeared with a new injection of volcanic aerosols into the stratosphere. A similar pattern of correlation has been found for changes in current density in the global electric circuit and for changes in relativistic electron precipitation. Several other weather and climate variations have been found to correlate with changes in air-earth current density due to solar wind modulation of the global electric circuit. The accumulation of electrostatic charge on supercooled droplets at cloud tops responds to air-earth current density changes. A mechanism linking the effects of charge accumulation to changes in ice nucleation, precipitation efficiency, latent heat retention and perturbations in atmospheric dynamics is thus as an explanation for this and other solar wind - atmospheric electricity - weather and climate correlations.

Tinsley, B.A.; Hoeksema, J.T.; Baker, D.N. [Univ. of Texas, Richardson, TX (United States)]|[Stanford Univ., Stanford, CA (United States)]|[Univ. of Colorado, Boulder, CO (United States)

1994-08-01

244

Convective heat loss and change in body temperature of grasshopper and locust nymphs: Relative importance of wind speed, insect size and insect orientation  

Microsoft Academic Search

1.1. Grasshopper (Melanoplus sanguinipes, M. bivittatus) and locust (Locusta migratoria migratorioides) (Orthoptera: Acrididae) nymphs were oriented at angles to the wind stream at four wind speeds.2.2. Rates of temperature and energy change due to convection were measured after compensating for Stefan-Boltzmann radiative energy exchange.3.3. The rate constant for Newton's law of cooling, and the convective heat-transfer coefficient were both affected

Derek J. Lactin; Dan L. Johnson

1998-01-01

245

Control of interplanetary solar wind sector polarity on changes in the ionosphere  

NASA Astrophysics Data System (ADS)

Solar sector polarity effects on the ionosphere may provide some clues in understanding of the ionospheric day-to-day variability. In this study, a solar-terrestrial connection ranging from solar sector boundary (SB) crossings, geomagnetic disturbances and ionospheric perturbations has been demonstrated. Superposed epoch analysis confirms that the increases in interplanetary solar wind speed within three days after SB crossings and the decreases in solar wind dynamic pressure and magnetic field intensity immediately after SB crossings. Furthermore, the interplanetary magnetic field (IMF) Bz component turns from northward to southward in March equinox and June solstice as the Earth passes from a solar sector of outward to inward directed magnetic fields, whereas the reverse situation occurs for the transition from toward to away sectors. For the same solar sector polarity there are opposite IMF Bz components between March and September equinox, and between June and December solstice. The F2 region critical frequency (foF2) covering about four solar cycles and total electron content (TEC) during 1998-2011 are utilized to extract how the ionosphere reacts to the interplanetary solar wind variations linkage of SB crossings. foF2 vary within the range of ±15% on average. The responses of the ionospheric TEC to SB crossings exhibit complex temporal and spatial variations and have strong dependencies on season, latitude, and solar cycle. This effect is more appreciable in equinoctial months than in solstitial months. In September equinox, relative variations of foF2 at noon are depressed at high latitudes and enhanced in low-equatorial latitudes during IMF away sectors. This research was supported by Chinese Academy of Sciences (KZZD-EW-01-3), National Key Basic Research Program of China (2012CB825604) and National Natural Science Foundation of China (41231065).

Liu, Libo; Liu, Jing; Zhao, Biqiang; Wan, Weixing

2013-04-01

246

Late Holocene changes in precipitation in northwest Tasmania and their potential links to shifts in the Southern Hemisphere westerly winds  

NASA Astrophysics Data System (ADS)

Accurate projections of future climate changes in regions susceptible to drought depend on a good understanding of past climate changes and the processes driving them. In the absence of longer term instrumental data, paleoclimate data are needed. In this study we develop a precipitation reconstruction for Rebecca Lagoon (41°11?S, 144°41?E), northwest Tasmania. First, the relationship between scanning reflectance spectroscopy measurements of sediment cores in the visible spectrum (380-730 nm) and instrumental precipitation record (1912-2009) was used to develop a model to reconstruct precipitation back in time. Results showed that the ratio of reflectance between 660 and 670 nm (i.e., reflectance at 660 nm/reflectance at 670 nm; a measure of pigment diagenesis) was significantly related to annual precipitation. A calibration model was developed (R = - 0.56, pauto < 0.001, RMSEP = 43.0 mm yr- 1, 5 year triangular filtered data, calibration period 1912-2009). Second, this calibration-in-time model was used to reconstruct late Holocene precipitation changes over the last ~ 3000 years. This showed relatively dry conditions from ca. 3100-2800 cal yr BP, wet conditions from ca. 2800-2400 cal yr BP, dry conditions from ca. 2400-2000 calyr BP, and variable conditions after this. Relatively wet conditions occurred from ca. 500 cal yr BP to the late AD 1800 s (ca. 50 cal. yr BP). The precipitation reconstruction indicates that conditions were relatively dry for the 20th century compared to the last ~ 3000 years. In particular, the dry period measured in recent decades is one of the most intense in at least the last 500 years. As precipitation in this region is primarily driven by the Southern Hemisphere westerly winds, these changes are discussed in terms of shifts in westerly wind strength and/or position.

Saunders, K. M.; Kamenik, C.; Hodgson, D. A.; Hunziker, S.; Siffert, L.; Fischer, D.; Fujak, M.; Gibson, J. A. E.; Grosjean, M.

2012-07-01

247

Implications of global change and climate variability for vector-borne diseases: generic approaches to impact assessments  

Microsoft Academic Search

Global change is pervasive and occurring at a dramatic rate. It involves changes in land use, vegetation cover, species translocations and even the climate of the planet. The consequences for the biosphere are uncertain. Past research emphasis has been on the science of climate change as the major driver of policy. The present priority in the global-change community is to

R. W Sutherst

1998-01-01

248

Simulation of Variable Speed Wind Generation System Using Boost Converter of Permanent Magnet Synchronous Generator  

NASA Astrophysics Data System (ADS)

This paper proposes variable-speed wind generation system using the boost converter. The proposed system has three speed control modes for the wind velocity. The control mode of low wind velocity regulates the armature current of the generator with the boost converter to control the speed of wind turbine. The control mode of middle wind velocity regulates the DC link voltage with the vector controlled inverter to control the speed of wind turbine. The control mode of high wind velocity regulates the pitch angle of the wind turbine with the pitch angle control system to control the speed of wind turbine. The hybrid of three control modes extends the variable-speed range. The proposed system simplifies the maintenance and improves the reliability and reduces the cost in compare with the variable-speed wind generation system using PWM converter. This paper describes the control strategy and modeling for simulation using Matlab Simulink of the proposed system. Also this paper describes the control strategy and modeling of variable-speed wind generation system using PWM converter. The steady state and transient responses for wind velocity changes are simulated using the Matlab Simulink. This paper verifies the fundamental performance of the system using boost converter by discussing the simulation results of the both systems.

Ohyama, Kazuhiro; Sakamoto, Tsuyoshi; Arinaga, Shinji; Yamashita, Yukio

249

A Simulation Study of the Response of the Jovian Magnetosphere to Changes in the Solar Wind Dynamic Pressure and Interplanetary Magnetic Field  

Microsoft Academic Search

A rapidly rotating equatorial current sheet and plasma sheet dominates the Jovian magnetosphere. We have used a global magnetohydrodynamic (MHD) simulation to investigate the effects of changes in the solar wind dynamic pressure and interplanetary magnetic field (IMF) on the Jovian magnetospheric configuration with emphasis on changes in the equatorial plasma sheet. We have carried out three numerical experiments: 1.

R. J. Walker; T. Ogino; K. Fukazawa

2003-01-01

250

Stratospheric volcanic aerosols and changes in air-earth current density at solar wind magnetic sector boundaries as conditions for the Wilcox tropospheric vorticity effect  

Microsoft Academic Search

A correlation between tropospheric dynamics and solar wind magnetic fields that disappeared in the early 1970s reappeared with a new injection of volcanic aerosols into the stratosphere. A similar pattern of correlation has been found for changes in current density in the global electric circuit and for changes in relativistic electron precipitation. Several other weather and climate variations have been

Brian A. Tinsley; J. Todd Hoeksema; Daniel N. Baker

1994-01-01

251

Into the Wind, Against the Tide: Change and the Operational Commander.  

National Technical Information Service (NTIS)

This paper discusses the operational commander's role in ensuring effective change. Its purpose is to answer two basic questions: (1) What are the barriers to operational commanders' effective response to change; and (2) How can commanders successfully ov...

J. M. Parker

1994-01-01

252

LARGE CHANGES IN LOESS GEOCHEMISTRY AND HIGH LATITUDE WIND REGIMES DURING THE LAST TWO MILLION YEARS, CENTRAL ALASKA  

NASA Astrophysics Data System (ADS)

Ice wedge casts and thermokarst deposits near the base of 80-m-high loess cliffs at Gold Hill record a cycle of transient climate cooling and permafrost formation followed by an interval of climate warming and permafrost degradation about two million years ago (Beget et al., 2008). Ice wedge casts and thermokarst features occur below the PA tephra (ca. 2.02 myr) but formed after the Reunion paleomagnetic excursion (ca. 2.14 myr), suggesting the Alaskan cold interval was correlative with marine isotope stage 77, a time of significant global glaciation and cooling. The subsequent period of ice wedge thawing records warmer conditions, probably during marine isotope stage 76. Magnetic susceptibility profiling of the 2 MA Alaskan loess reveals glacial-interglacial cycles similar to those seen in late Pleistocene loess. However, new geochemical data from the 2 MA loess shows that it was significantly more calcareous then late Pleistocene loess and contains numerous calcareous concretions, some weighing as much as several kg. For most of the past two million years the loess geochemistry indicates winds came dominantly from the south and southwest carrying non-calcarous silts derived from glaciation of the Alaska Range, with only a minor eolian contribution from the calcareous-rich silts of the Yukon River. The calcareous loess deposits that formed 2.1 MA record eolian silt transport from the Yukon River and the calcareous Brooks Range to the north. The loess record shows that an interval characterized by a major shift in the atmospheric circulation regime from one dominated by southerly winds from the northern Pacific Ocean and Gulf of Alaska to one dominated by northerly winds from the Chuckchi Sea and western Arctic Ocean areas occurred ca. 2.1 MA. At least one additional interval of calcareous loess deposition also occurs in mid-Pleistocene time, and records another large but transient change in high latitude atmospheric circulation at ca. 0.4-0.5 MA.

Keskinen, M. J.; Beget, J. E.

2009-12-01

253

Climate change effects on mitigation measures: The case of extreme wind events and Philippines’ biofuel plan  

Microsoft Academic Search

Biofuel production has increased dramatically over the past decade, among other to mitigate climate change. However, climate change vulnerability may currently not be sufficiently accounted for in national biofuel strategies, hence neglecting a possible link between mitigation and adaptation to climate change. To the best of our knowledge this potential link has received very little attention in the literature. One

Per M. Stromberg; Miguel Esteban; Alexandros Gasparatos

254

Long-term measurements of lower thermospheric neutral winds over Poker Flat, Alaska  

Microsoft Academic Search

The Poker Flat Incoherent Scatter Radar (PFISR) commenced routine operations in March 2007. Starting in late 2007 software changes made it possible to make nearly continuous measurements of ionospheric parameters, including estimates of velocity vectors. This enables the estimation of neutral winds over the altitude range of ~90 to 120 km for much of the time from early 2008 to

C. J. Heinselman; M. J. Nicolls

2010-01-01

255

Changing Climate and Wind Patterns Revealed in Indiana's Fair Oaks Dunes  

NASA Astrophysics Data System (ADS)

Fair Oak Dunes (FOD) cover over 1100 square miles in north-central Indiana. Careful study of dune morphology reveals three types of dunes in regards to their size. The first order forms are compound parabolic dunes that reach over five miles in length and have the apex of parabola pointing in a southwesterly direction. The spacing between these dunes is three to five miles. The second order dune ridges are compound parabolic dunes that range in size from one to three miles in length with spacing of about one mile between the ridges. Both, the second order and the third order dunes have the apex of parabola pointing in northeasterly direction, opposite of the first order dunes. The third order dune ridges are simple parabolic dunes that reach up to half mile in length and are 25 to 30 feet tall in western part to over 45 feet in the eastern part of the FOD. All dunes are fixed by lush vegetation. Preliminary grain size analyses indicate that north part of FOD has coarser sand (0.283 mm) than southern part (0.197 mm), while eastern part (0.271 mm) is coarser than the western part (0.223 mm). This grain size distribution is in accordance with initial interpretation of dune morphology. Strong northeasterly winds associated with anticyclone were prevalent in early dune formation about 14,000 years ago near the end of last glacial. The finest particles were blown south and southwest from the source area which was north and east of the present dunes. Cyclonic southwesterly winds become dominant in Holocene and caused a reworking of the original large dunes into smaller forms as well as removal of some of the finest particles back to the original source to the northeast. Limited vertical dune profiles indicate that below the 5 feet of bioturbated surface layer are alternating light layers (3 to 5 inch thick) and dark laminae (1-2 inches thick). Dark laminae consist of quartz grains with `hairy' surfaces covered with reddish iron oxides or clays. They contain twice as much silt fraction and are more indurated and resistant to weathering than light layers separating them. Are these alternating layers depositional or postdepositional structures? Depositional origin would indicate episodes of drier climate and strong winds creating light, coarser layers while dark laminae would be indication of wet climate and weak winds transporting only dust particles. Postdepositional origin would indicate formation of "dissipation structures" created by soil water translocation of fines during humid climate. Many of the questions about timing of original dunes and their later transformation as well as timing of dark laminae and light layers within the dunes will hopefully be answered by OSL dating.

Kilibarda, Z.

2004-12-01

256

Decades-Long Changes of the Interstellar Wind Through Our Solar System  

NASA Astrophysics Data System (ADS)

The journey of the Sun through the dynamically active local interstellar medium creates an evolving heliosphere environment. This motion drives a wind of interstellar material through the heliosphere that has been measured with Earth-orbiting and interplanetary spacecraft for 40 years. Recent results obtained by NASA's Interstellar Boundary Explorer mission during 2009–2010 suggest that neutral interstellar atoms flow into the solar system from a different direction than found previously. These prior measurements represent data collected from Ulysses and other spacecraft during 1992–2002 and a variety of older measurements acquired during 1972–1978. Consideration of all data types and their published results and uncertainties, over the three epochs of observations, indicates that the trend for the interstellar flow ecliptic longitude to increase linearly with time is statistically significant.

Frisch, P. C.; Bzowski, M.; Livadiotis, G.; McComas, D. J.; Moebius, E.; Mueller, H.-R.; Pryor, W. R.; Schwadron, N. A.; Sokó?, J. M.; Vallerga, J. V.; Ajello, J. M.

2013-09-01

257

Short Time Scale Changes in Underwater Irradiance in a Wind-exposed Lagoon (Vaccarès Lagoon, France): Efficiency of Infrequent Field Measurements of Water Turbidity or Weather Data to Predict Irradiance in the Water Column  

Microsoft Academic Search

High frequency water sampling in the wind-exposed Vaccarès lagoon revealed frequent and rapid changes in suspended solid (SS) concentrations in the water column. SS concentrations, sometimes higher than 800 mg l?1, were significantly correlated with antecedent wind conditions. Mean wind velocity during the 5–33 h before water sampling or maximal wind velocity during the previous 8.5–22 h were good predictors of SS concentrations

Damien Banas; Patrick Grillas; Isabelle Auby; François Lescuyer; Eric Coulet; Jean-Claude Moreteau; Bertrand Millet

2005-01-01

258

PULSED ALFVEN WAVES IN THE SOLAR WIND  

SciTech Connect

Using 3 s plasma and magnetic field data from the Wind spacecraft located in the solar wind well upstream from Earth, we report observations of isolated, pulse-like Alfvenic disturbances in the solar wind. These isolated events are characterized by roughly plane-polarized rotations in the solar wind magnetic field and velocity vectors away from the directions of the underlying field and velocity and then back again. They pass over Wind on timescales ranging from seconds to several minutes. These isolated, pulsed Alfven waves are pervasive; we have identified 175 such events over the full range of solar wind speeds (320-550 km s{sup -1}) observed in a randomly chosen 10 day interval. The large majority of these events are propagating away from the Sun in the solar wind rest frame. Maximum field rotations in the interval studied ranged from 6 Degree-Sign to 109 Degree-Sign . Similar to most Alfvenic fluctuations in the solar wind at 1 AU, the observed changes in velocity are typically less than that predicted for pure Alfven waves (Alfvenicity ranged from 0.28 to 0.93). Most of the events are associated with small enhancements or depressions in magnetic field strength and small changes in proton number density and/or temperature. The pulse-like and roughly symmetric nature of the magnetic field and velocity rotations in these events suggests that these Alfvenic disturbances are not evolving when observed. They thus appear to be, and probably are, solitary waves. It is presently uncertain how these waves originate, although they may evolve out of Alfvenic turbulence.

Gosling, J. T. [Laboratory for Atmospheric and Space Physics, University of Colorado, 1234 Innovation Drive, Boulder, CO 80303 (United States); Tian, H. [High Altitude Observatory, National Center for Atmospheric Research, Boulder, CO 80307 (United States); Phan, T. D., E-mail: jack.gosling@lasp.colorado.edu [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)

2011-08-20

259

Development policy for non-grid-connected wind power in China: An analysis based on institutional change  

Microsoft Academic Search

Government policy continues to play a crucial role in the development of wind power industry in China. The 2005 “Renewable Energy Law†and related policies have driven the rapid increase in wind power installed capacity in China over the past half-decade, with capacity doubling annually since 2005. However, a large number of wind farms generate electricity well below their installed

Yong Fang; Jing Li; Mingming Wang

2012-01-01

260

Changes in solar wind-magnetosphere coupling with solar cycle, season, and time relative to stream interfaces  

NASA Astrophysics Data System (ADS)

Geomagnetic activity depends on a variety of factors including solar zenith angle, solar UV, strength of the interplanetary magnetic field, speed and density of the solar wind, orientation of the Earth’s dipole, distance of the Earth from Sun, occurrence of CMEs and CIRs, and possibly other parameters. We have investigated some of these using state-dependant linear prediction filters. For a given state a prediction filter transforms a coupling function such as rectified solar wind electric field (VBs) to an output like the auroral electrojet index (AL). The area of this filter calculated from the sum of the filter coefficients measures the strength of the coupling. When the input and output are steady for a time longer than the duration of the filter the ratio of output to input is equal to this area. We find coupling strength defined in this way for Es=VBs to AL (and AU) is weakest at solar maximum and strongest at solar minimum. AL coupling displays a semiannual variation being weakest at the solstices and strongest at the equinoxes. AU coupling has only an annual variation being strongest at summer solstice. AL and AU coupling also vary with time relative to a stream interface. Es coupling is weaker after the interface, but ULF coupling is stronger. Total prediction efficiency remains about constant at the interface. The change in coupling strength with the solar cycle can be explained as an effect of more frequent saturation of the polar cap potential causing a smaller ratio of AL to Es. Stronger AL coupling at the equinoxes possibly indicates some process that makes magnetic reconnection less efficient when the dipole axis is tilted along the Earth-Sun line. Strong AU coupling at summer solstice is likely due to high conductivity in northern summer. Coupling changes at a stream interface are correlated with the presence of strong wave activity in ground and satellite measurements and may be an artifact of the method by which solar wind data are propagated.

McPherron, Robert L.; Baker, Daniel N.; Pulkkinen, T. I.; Hsu, T.-S.; Kissinger, J.; Chu, X.

2013-07-01

261

Water dispersal as an additional pathway to invasions by the primarily wind-dispersed tree Ailanthus altissima  

Microsoft Academic Search

Long-distance dispersal is a key process in biological invasions. Previous research has emphasized the role of nonstandard\\u000a dispersal vectors, but consequences of a change in dispersal vector for the establishment of invasive plant species have received\\u000a less attention. We analyzed how water-mediated dispersal rather than the more expected wind-mediated dispersal can affect\\u000a the establishment of the invasive tree Ailanthus altissima

Ingo Kowarik; Ina Säumel

2008-01-01

262

Observed Near-Surface Currents Under High Wind Speeds.  

National Technical Information Service (NTIS)

From the Surface Velocity Program (SVP) drifter current and QuikSCAT wind data, the relationship between the observed near-surface current vectors and surface wind vectors for the northwestern Pacific Ocean under high winds (20 50 m s expn -1) are obtaine...

G. Chen L. R. Centurioni P. C. Chu R. Tseng Y. Chang

2012-01-01

263

Changes in thermospheric temperature induced by high-speed solar wind streams  

NASA Astrophysics Data System (ADS)

During high-speed stream (HSS) events the solar wind speed increases, and the cross polar cap potential increases, leading to increased Joule heating at high latitudes. The heat input at high latitudes heats the polar regions, which then conducts to lower latitudes, producing global heating. The heating occurs during the risetime of the cross polar cap potential and throughout the period of high cross polar cap potential as seen in our simulation. These simulations are performed using the Utah State University global thermosphere model driven by Joule heating rates that are consistent with electric fields observed by DMSP-15 observations of HSS events. Cooling occurs as the cross polar cap potential decreases and continues for several days after the cross polar cap potential has returned to background values. Polar cap ionospheric observations are compared to model simulations of heating and cooling, providing evidence that the thermospheric model is capturing the HSS energy input and the post-HSS multiday return to pre-HSS conditions. The HSS heating can be as high as 100 K (as seen from both the model and the data) at high latitudes, with a corresponding, but lower, global increase in thermospheric temperature.

Gardner, Larry; Sojka, Jan J.; Schunk, Robert W.; Heelis, Rod

2012-12-01

264

Deceleration of the solar wind upstream from the earth's bow shock and the origin of diffuse upstream ions  

Microsoft Academic Search

Observations with the Los Alamos Scientific Laboratory\\/Max-Planck-Institut crossed-fan solar wind ion experiment on ISEE 1 reveal that the solar wind is decelerated and deflected away from the direction of the earth's bow shock as it enters that portion of the upstream region populated by 'diffuse' bow shock ions and long-period (10--60 s) waves. Typically, the average directed velocity vector changes

S. J. Bame; J. R. Asbridge; W. C. Feldman; J. T. Gosling; G. Paschmann; N. Sckopke

1980-01-01

265

Wind turbine  

DOEpatents

A wind turbine of the type having an airfoil blade (15) mounted on a flexible beam (20) and a pitch governor (55) which selectively, torsionally twists the flexible beam in response to wind turbine speed thereby setting blade pitch, is provided with a limiter (85) which restricts unwanted pitch change at operating speeds due to torsional creep of the flexible beam. The limiter allows twisting of the beam by the governor under excessive wind velocity conditions to orient the blades in stall pitch positions, thereby preventing overspeed operation of the turbine. In the preferred embodiment, the pitch governor comprises a pendulum (65,70) which responds to changing rotor speed by pivotal movement, the limiter comprising a resilient member (90) which engages an end of the pendulum to restrict further movement thereof, and in turn restrict beam creep and unwanted blade pitch misadjustment.

Cheney, Jr., Marvin C. (Glastonbury, CT)

1982-01-01

266

Wind turbine  

SciTech Connect

A wind turbine of the type having an airfoil blade mounted on a flexible beam and a pitch governor which selectively, torsionally twists the flexible beam in response to wind turbine speed thereby setting blade pitch, is provided with a limiter which restricts unwanted pitch change at operating speeds due to torsional creep of the flexible beam. The limiter allows twisting of the beam by the governor under excessive wind velocity conditions to orient the blades in stall pitch positions, thereby preventing overspeed operation of the turbine. In the preferred embodiment, the pitch governor comprises a pendulum which responds to changing rotor speed by pivotal movement, the limiter comprising a resilient member which engages an end of the pendulum to restrict further movement thereof, and in turn restrict beam creep and unwanted blade pitch misadjustment.

Cheney, M.C.

1982-10-05

267

Electrical Wind Force-Driven and Dislocation-Templated Amorphization in Phase-Change Nanowires  

NASA Astrophysics Data System (ADS)

Phase-change materials undergo rapid and reversible crystalline-to-amorphous structural transformation and are being used for nonvolatile memory devices. However, the transformation mechanism remains poorly understood. We have studied the effect of electrical pulses on the crystalline-to-amorphous phase change in a single-crystalline Ge2Sb2Te5 (GST) nanowire memory device by in situ transmission electron microscopy. We show that electrical pulses produce dislocations in crystalline GST, which become mobile and glide in the direction of hole-carrier motion. The continuous increase in the density of dislocations moving unidirectionally in the material leads to dislocation jamming, which eventually induces the crystalline-to-amorphous phase change with a sharp interface spanning the entire nanowire cross section. The dislocation-templated amorphization explains the large on/off resistance ratio of the device.

Nam, Sung-Wook; Chung, Hee-Suk; Lo, Yu Chieh; Qi, Liang; Li, Ju; Lu, Ye; Johnson, A. T. Charlie; Jung, Yeonwoong; Nukala, Pavan; Agarwal, Ritesh

2012-06-01

268

Directional trends in thermospheric neutral winds observed at Arecibo during the past three solar cycles  

NASA Astrophysics Data System (ADS)

Since 1980, we have observed the thermospheric neutral wind at the Arecibo Observatory using a Fabry-Perot interferometer to measure the O(1D) 630 nm emission. Burnside and Tepley (1989) examined the first 8 years of this extended data set and found that there were no significant or systematic solar cycle influences on the magnitude or direction of the neutral wind field, nor on its horizontal gradients. Such affects have been observed previously at other locations around the globe, and their absence at Arecibo may have been due to the limited data set. Thus, we have extended the period of acquisition and analysis of our neutral wind measurements to include nearly three complete solar cycles (or approximately 30 years) and will present our results within the framework of the earlier work. While the earlier conclusion that no major systematic solar cycle influence on the neutral winds at Arecibo generally remains intact, we did find a slight increase in wind magnitude and a gradual, yet consistent rotation of the thermospheric neutral wind vector from a general southeast to a more eastward flow during 30 years of observation. We explain the magnitude and directional variations in terms of long-term changes in the density and temperature of the upper atmosphere and their possible dissimilar influences on each wind component that appear as a rotation of the neutral wind vector.

Tepley, C. A.; Robles, E.; García, R.; Santos, P. T.; Brum, C. M.; Burnside, R. G.

2011-06-01

269

Response to Patterson's "Winds of Change for Client-Centered Counseling."  

ERIC Educational Resources Information Center

|Responds to previous article by Patterson in which Patterson defends Rogers' theory of psychotherapy and the traditional form in which it is practiced by many client-centered counselors. Shares Patterson's concern about the changes being advocated for client-centered counseling on the grounds that the approach is inadequate. Attempts to clarify…

Brodley, Barbara Temaner

1993-01-01

270

Estimation of climate effects of land use changes with simple wind models  

Microsoft Academic Search

Land has an important role in the climate system. Its spatial and temporal variability exceeds the ocean’s. Roughness properties and participation of land in the moisture exchange process underline its importance. Because of increasing land degradation and land use change in the last century a better understanding of these processes is required. For this purpose several new modelling approaches have

Kornélia Radics; Judit Bartholy

2002-01-01

271

The Winds of Change in Russian Higher Education: Is the East Moving West?  

ERIC Educational Resources Information Center

|In the last 30 years, major changes have taken place in the public sector worldwide under the rubric of New Public Management [NPM]. The education sector is perhaps one of the key areas drawing an intense interest and discussion in the wake of NPM. The Russian State seems to be no longer an exception to this global trend. In line with this, the…

Timoshenko, Konstantin

2011-01-01

272

Winds of Change in the English Language--Air of Peril for Native Speakers?  

ERIC Educational Resources Information Center

|English today is one of the most hybrid and rapidly changing languages in the world. New users of the language are not just passively absorbing, but actively shaping it, breeding a variety of regional Englishes, as well as pidgins and English-lexified creoles. Also, as in an increasing number of countries English is becoming an element of core…

Paradowski, Michal B.

2008-01-01

273

Winds of Change: Latinos in the Heartland and the Nation. JSRI Statistical Brief No. 5.  

ERIC Educational Resources Information Center

|This statistical brief provides a follow-up assessment of the changing demographic and economic landscape of the Midwest between 1980 and 1990. Latino population growth in the Midwest during the 1980s was modest, but since the region's other groups experienced minimal or negative growth, Latino growth accounted for over half the Midwest's total…

Aponte, Robert; Siles, Marcelo E.

274

Vector carpets  

SciTech Connect

Previous papers have described a general method for visualizing vector fields that involves drawing many small ``glyphs`` to represent the field. This paper shows how to improve the speed of the algorithm by utilizing hardware support for line drawing and extends the technique from regular to unstructured grids. The new approach can be used to visualize vector fields at arbitrary surfaces within regular and unstructured grids. Applications of the algorithm include interactive visualization of transient electromagnetic fields and visualization of velocity fields in fluid flow problems.

Dovey, D.

1995-03-22

275

Vector Calculus  

NSDL National Science Digital Library

This is a series of lectures, authored by Chris Tisdell of the University of New South Wales, for MATH2111 "Higher Several Variable Calculus" and "Vector Calculus", which is a 2nd-year mathematics subject taught at UNSW, Sydney. This playlist provides a shapshot of some lectures presented in Session 1, 2009. These lectures focus on presenting vector calculus in an applied and engineering context, while maintaining mathematical rigour. Thus, this playlist may be useful to students of mathematics, but also to those of engineering, physics and the applied sciences. There is an emphasis on examples and also on proofs.

Tisdell, Chris

2010-12-16

276

Vectors, Change of Basis and Matrix Representation: Onto-Semiotic Approach in the Analysis of Creating Meaning  

ERIC Educational Resources Information Center

In a previous study, the onto-semiotic approach was employed to analyse the mathematical notion of different coordinate systems, as well as some situations and university students' actions related to these coordinate systems in the context of multivariate calculus. This study approaches different coordinate systems through the process of change of…

Montiel, Mariana; Wilhelmi, Miguel R.; Vidakovic, Draga; Elstak, Iwan

2012-01-01

277

Observed And Predicted Flow Variability Over The Baltic Region: Implications Of Climate Change For Wind Energy Viability  

Microsoft Academic Search

We present analysis of historical and prognostic future flow regimes in the Baltic with the perspective of the viability of wind energy. Analysis of 850 hPa wind speeds as manifest in the NCEP\\/NCAR reanalysis fields over the Baltic region indicates annual mean wind speeds over the Baltic significantly increased over the period 1953-1999 with the majority of the increase being

S. C. Pryor; R. J. Barthelmie; J. T. Schoof

2003-01-01

278

Linking Inuit knowledge and meteorological station observations to understand changing wind patterns at Clyde River, Nunavut  

Microsoft Academic Search

Connecting indigenous and scientific observations and knowledge has received much attention in the Arctic, not least in the\\u000a area of climate change. On some levels, this connection can be established relatively easily, linking observations of similar\\u000a phenomena or of various effects stemming from the same cause. Closer examinations of specific environmental parameters, however,\\u000a can lead to far more complex and

Shari Gearheard; Matthew Pocernich; Ronald Stewart; Joelie Sanguya; Henry P. Huntington

2010-01-01

279

Assessing climate change impacts on the near-term stability of the wind energy resource over the United States.  

PubMed

The energy sector comprises approximately two-thirds of global total greenhouse gas emissions. For this and other reasons, renewable energy resources including wind power are being increasingly harnessed to provide electricity generation potential with negligible emissions of carbon dioxide. The wind energy resource is naturally a function of the climate system because the "fuel" is the incident wind speed and thus is determined by the atmospheric circulation. Some recent articles have reported historical declines in measured near-surface wind speeds, leading some to question the continued viability of the wind energy industry. Here we briefly articulate the challenges inherent in accurately quantifying and attributing historical tendencies and making robust projections of likely future wind resources. We then analyze simulations from the current generation of regional climate models and show, at least for the next 50 years, the wind resource in the regions of greatest wind energy penetration will not move beyond the historical envelope of variability. Thus this work suggests that the wind energy industry can, and will, continue to make a contribution to electricity provision in these regions for at least the next several decades. PMID:21536905

Pryor, S C; Barthelmie, R J

2011-05-02

280

Assessing climate change impacts on the near-term stability of the wind energy resource over the United States  

PubMed Central

The energy sector comprises approximately two-thirds of global total greenhouse gas emissions. For this and other reasons, renewable energy resources including wind power are being increasingly harnessed to provide electricity generation potential with negligible emissions of carbon dioxide. The wind energy resource is naturally a function of the climate system because the “fuel” is the incident wind speed and thus is determined by the atmospheric circulation. Some recent articles have reported historical declines in measured near-surface wind speeds, leading some to question the continued viability of the wind energy industry. Here we briefly articulate the challenges inherent in accurately quantifying and attributing historical tendencies and making robust projections of likely future wind resources. We then analyze simulations from the current generation of regional climate models and show, at least for the next 50 years, the wind resource in the regions of greatest wind energy penetration will not move beyond the historical envelope of variability. Thus this work suggests that the wind energy industry can, and will, continue to make a contribution to electricity provision in these regions for at least the next several decades.

Pryor, S. C.; Barthelmie, R. J.

2011-01-01

281

Wind Tubes  

NSDL National Science Digital Library

In this activity, learners create and experiment with wind tubes. These tubes are a playful and inventive way to explore the effect that moving air has on objects. Construction uses everyday materials such as a fan and embroidery hoops. Itâs fun to make things fly out of or float in the tubes, and to adjust the tubes to change the way the objects fly. The activity requires a significant amount of time and resources to build and may require adult help in construction. Experimentation with the wind tubes is engaging for a wide age range of learners.

Exploratorium

2012-12-14

282

Downscaling and predictability of historical monthly mean surface winds over a region of complex terrain and marine influence: Western Canada  

NASA Astrophysics Data System (ADS)

Surface wind is a vector quantity exhibiting high spatial and temporal variability. Consequently, it presents a challenge for methods of statistical downscaling, which are used to establish a relationship between the large-scale atmospheric flow (predictors) and local climate variables (predictands). Simple regression-based techniques, for example, used with success for smoother predictands such as temperature, may not be as effective when applied to wind. In this work, the predictability of surface wind magnitude and direction at 28 stations in Western Canada over the period 1979-2006 was assessed using NCEP-2 reanalysis fields to derive large-scale predictors. Specifically, a combined principal components (PC) analysis was employed with the wind components at 500 hPa and mean sea level pressure as input fields, and the first 5 PCs used as predictors. The predictands were either wind speed or vector wind components oriented along directions ranging from 0 to 170 degrees at 10 degree intervals. Multiple linear regression was used for the downscaling, and its robustness assessed via cross-validation with an associated Pearson R2 value. This approach might be expected to display relatively high predictability, since it is comprised almost entirely of observations. However, our findings show that often this is not the case. Overall, wind speed was poorly predicted (R2<0.5), with the exception of a handful of stations in autumn and winter. By contrast, wind components were predicted with better skill than wind speeds at nearly all stations year-round, with the highest R2 values in autumn (SON) and lowest values in summer (JJA). The predictability of wind components was found to depend upon the topographic character of the region surrounding a given station. In mountainous regions, e.g., predictive skill was strongly related to the orientation of the components, with the best predicted components oriented along topographically significant directions such as constricted valleys and ocean channels. Predictability at stations in regions of relatively flat terrain was less dependent on wind direction. The latter stations also displayed region-wide seasonal shifts in the direction of the most skillfully predicted wind component. In summary, at most stations in Western Canada, monthly mean vector wind components were more reliably predicted than wind speeds. This result complicates the assessment of local changes in mean wind speed, extremes, and wind energy under climate change that is often a desired outcome of the downscaling exercise using modelled fields as predictors. However, useful projections might still be obtained at stations where a single wind direction is dominant.

Curry, C.; van der Kamp, D.; Monahan, A. H.

2010-12-01

283

Saturn's Zonal Winds at Cloud Level  

NASA Astrophysics Data System (ADS)

We present an analysis of new cloud motion measurements in Saturn's atmosphere from Voyager 1 and 2 images and define a nominal zonal wind velocity vs latitude profile for the cloud top level that can be used as reference for the upcoming Cassini mission. Improvements over previous studies include: (i) twice the number of wind vectors used, (ii) independent measurements of cloud tracers, (iii) extended latitudinal coverage, (iv) strict error control and evaluation, and (v) a new zonal averaging methodology. Mean zonal wind velocities are given for the latitude range 81° to -71° (planetographic) in steps of 0.5° with a gap between 0° and -10° due to ring shadowing. This research also includes the study of the morphology and motions of cloud systems in the equator and in the southern hemisphere which have not been described previously. We give an ephemeris (motion equation) for several long-lived features that could be observable if they survive until Cassini arrives on Saturn. The long-term behavior of the zonal wind profile is studied by comparing it with a complete set of wind velocities compiled from historical and modern ground-based and HST observations. Significant changes are noted in the equatorial jet between this set and the nominal Voyager profile. We discuss in detail the possible origin for such differences.

Sanchez-Lavega, Agust?´n.; Rojas, José F.; Sada, Pedro V.

2000-10-01

284

Titan’s Rotation Reveals an Internal Ocean and Changing Zonal Winds  

NASA Astrophysics Data System (ADS)

Cassini radar observations of Saturn’s moon Titan over several years show that its rotational period is changing and is different from its orbital period. The present-day rotation period difference from synchronous spin leads to a shift of ~0.36° per year in apparent longitude and is consistent with seasonal exchange of angular momentum between the surface and Titan’s dense superrotating atmosphere, but only if Titan’s crust is decoupled from the core by an internal water ocean like that on Europa.

Lorenz, Ralph D.; Stiles, Bryan W.; Kirk, Randolph L.; Allison, Michael D.; Persi del Marmo, Paolo; Iess, Luciano; Lunine, Jonathan I.; Ostro, Steven J.; Hensley, Scott

2008-03-01

285

New techniques in 3D scalar and vector field visualization  

SciTech Connect

At Lawrence Livermore National Laboratory (LLNL) we have recently developed several techniques for volume visualization of scalar and vector fields, all of which use back-to-front compositing. The first renders volume density clouds by compositing polyhedral volume cells or their faces. The second is a ``splatting`` scheme which composites textures used to reconstruct the scalar or vector fields. One version calculates the necessary texture values in software, and another takes advantage of hardware texture mapping. The next technique renders contour surface polygons using semi-transparent textures, which adjust appropriately when the surfaces deform in a flow, or change topology. The final one renders the ``flow volume`` of smoke or dye tracer swept out by a fluid flowing through a small generating polygon. All of these techniques are applied to a climate model data set, to visualize cloud density and wind velocity.

Max, N.; Crawfis, R.; Becker, B.

1993-05-05

286

Effects of sea state on offshore wind resourcing in Florida  

NASA Astrophysics Data System (ADS)

Offshore resource assessment relies on estimating wind speeds at turbine hub height using observations typically made at substantially lower height. The methods used to adjust from observed wind speeds to hub height can impact resource estimation. The importance of directional sea state is examined, both as seasonal averages and as a function of the diurnal cycle. A General Electric 3.6 MW offshore turbine is used as a model for a power production. Including sea state increases or decreases seasonally averaged power production by roughly 1%, which is found to be an economically significant change. These changes occur because the sea state modifies the wind shear (vector wind difference between the buoy height and the moving surface) and therefore the extrapolation from the observation to hub height is affected. These seemingly small differences in capacity can alter profits by millions of dollars depending upon the size of the farm and fluctuations in price per kWh throughout the year. A 2% change in capacity factor can lead to a 10 million dollar difference from total kWh produced from a wind farm of 100 3.6MW turbines. These economic impacts can be a deciding factor in determining whether a resource is viable for development. Modification of power output due to sea states are shown for seasonal and diurnal time scales. Three regions are examined herein: West Florida, East Florida, and Nantucket Sound. The average capacity after sea state is included suggests areas around Florida could provide substantial amounts of wind power throughout three-fourths of the calendar year. At certain times of day winter average produced capacity factors in West Florida can be up to 45% more than in summer when sea state is included. Nantucket Sound capacity factors are calculated for comparison to a region near a planned United States offshore wind farm. This study provides evidence to suggest including sea state in offshore wind resource assessment causes economically significant differences for offshore wind power siting.

Collier, Cristina

287

Determination of the effect of wind velocity and direction changes on turbidity removal in rectangular sedimentation tanks.  

PubMed

In the present study, a pilot-scale sedimentation tank was used to determine the effect of wind velocity and direction on the removal efficiency of particles. For this purpose, a 1:20 scale pilot simulated according to Frude law. First, the actual efficiency of total suspended solids (TSS) removal was calculated in no wind condition. Then, the wind was blown in the same and the opposite directions of water flow. At each direction TSS removal was calculated at three different velocities from 2.5 to 7 m/s. Results showed that when the wind was in the opposite direction of water flow, TSS removal efficiency initially increased with the increase of wind velocity from 0 to 2.5 m/s, then it decreased with the increase of velocity to 5 m/s. This mainly might happen because the opposite direction of wind can increase particles' retention time in the sedimentation tank. However, higher wind velocities (i.e. 3.5 and 5.5 m/s) could not increase TSS removal efficiency. Thus, if sedimentation tanks are appropriately exposed to the wind, TSS removal efficiency increases by approximately 6%. Therefore, energy consumption will be reduced by a proper site selection for sedimentation tank unit in water and waste water treatment plants. PMID:23109603

Khezri, Seyed Mostafa; Biati, Aida; Erfani, Zeynab

2012-01-01

288

Optimization of satellite coverage in observing cause and effect changes in the ionosphere, magnetosphere, and solar wind. Master's thesis  

SciTech Connect

Disturbances in the ionosphere sometimes cause adverse effects to communications systems, power grids, etc. on the earth. Currently, very little, if any, lead time is given to warn of an impending problem. If a forecast could be made of ionospheric occurrences, some lead time may be given to appropriate agencies and equipment may be saved. Most changes that occur in the ionosphere are a result of interaction of energy, currents, etc. between the magnetosphere and/or solar wind. Before a forecast can be made, however, improvement of ionospheric models currently in use need to be made. The models currently depict features in various regions of the ionosphere but not always where these features are actually observed. So an improvement to the model is needed to create an accurate baseline condition, or in other words an accurate depiction of the current ionosphere. Models could be improved by inputting real-time data from the ionosphere into the model. This data would come from satellites and/or ground-based stations.

Loveless, M.J.

1993-06-01

289

Surface freshening in the Arctic Ocean's Eurasian Basin: An apparent consequence of recent change in the wind-driven circulation  

NASA Astrophysics Data System (ADS)

Data collected by an autonomous ice-based observatory that drifted into the Eurasian Basin between April and November 2010 indicate that the upper ocean was appreciably fresher than in 2007 and 2008. Sea ice and snowmelt over the course of the 2010 drift amounted to an input of less than 0.5 m of liquid freshwater to the ocean (comparable to the freshening by melting estimated for those previous years), while the observed change in upper-ocean salinity over the melt period implies a freshwater gain of about 0.7 m. Results of a wind-driven ocean model corroborate the observations of freshening and suggest that unusually fresh surface waters observed in parts of the Eurasian Basin in 2010 may have been due to the spreading of anomalously fresh water previously residing in the Beaufort Gyre. This flux is likely associated with a 2009 shift in the large-scale atmospheric circulation to a significant reduction in strength of the anticyclonic Beaufort Gyre and the Transpolar Drift Stream.

Timmermans, M.-L.; Proshutinsky, A.; Krishfield, R. A.; Perovich, D. K.; Richter-Menge, J. A.; Stanton, T. P.; Toole, J. M.

2011-08-01

290

A twisted flow wind tunnel for testing yacht sails  

Microsoft Academic Search

The paper outlines the requirements for wind tunnel testing model yachts for sail aerodynamics investigations. It is shown that the apparent wind onto a yacht is “twisted” over the mast height, due to the vector addition of the yacht and wind velocities. The design features of a special wind tunnel built in New Zealand which can produce twisted flow in

Richard G. J. Flay

1996-01-01

291

Roles of surface wind, NDVI and snow cover in the recent changes in Asian dust storm occurrence frequency  

NASA Astrophysics Data System (ADS)

This paper describes the recent variations in dust outbreak during the period from 1996 to 2007 over the Asian dust source regions. The Asian dust source regions were divided into four sub-regions; S1, Taklamakan; S2, Gobi; S3, Inner Mongolia-Manchuria; and S4, Loess, and the WMO SYNOP observation and satellite data were employed to analyze the features of recently changed dust outbreak frequencies (DOFs). There was no particular variation in region S1, but the recent spatiotemporal variations in DOFs over S2-S4 were well characterized by a severe and widespread increase in 2001-2002, and significant decreasing in 2003-2004 over the most source regions, with a steadily increasing trend again during 2005-2007. Seasonal features showed that the highest DOFs occurred in March-April before 2002, but was delayed by a month toward April-May during the next five years because of the shift in the month of highest strong wind-speed frequencies (SWFs). A secondary peak of DOF was also found, occurring in October-November since the year 2000. Over all the source regions, the primary controlling factor for explaining the spatiotemporal DOF patterns was the SWF, with a pattern correlation coefficient (PCC) of 0.66-0.76. Other secondary controlling factors varied from region to region. For example, the DOFs observed in region S2-S3 showed relatively greater sensitivity to the snow-cover fraction, and region S4 showed a better correlation with the normalized difference vegetation index (NDVI) than the other regions. Other recent significant changes in DOFs over the Asian dust source regions and their causes are also discussed in this study.

Lee, Jong-Jae; Kim, Cheol-Hee

2012-11-01

292

PhET Simulation: Vector Addition  

NSDL National Science Digital Library

This applet allows user to learn how to add vectors. Users may drag vectors onto a graph, changing their length and angle, and calculate their sum. The magnitude, angle, and components of each vector can be displayed in several formats. Teaching ideas and activities are included. This is part of a larger collection developed by the Physics Education Technology project (PhET).

2008-07-13

293

WindSat-space borne remote sensing of Ocean surface winds  

Microsoft Academic Search

Summary form only given. For more than ten years, seven SSM\\/Is have successfully provided reliable passive microwave data for retrieving environmental parameters such as wind speed, sea ice concentration and age, and integrated atmospheric water vapor. One parameter not provided by microwave radiometers is the ocean surface wind direction. The wind vector affects a broad range of naval missions, including

P. W. Gaiser; K. M. St Germain; E. M. Twarog

2003-01-01

294

First Observations of Simultaneous Inter-hemispheric Conjugate High-latitude Thermospheric Winds  

NASA Astrophysics Data System (ADS)

We report the first observations of simultaneous high-latitude inter-hemispheric F-region neutral wind fields by combining the 630 nm optical measurements from two scanning Doppler imagers (SDI) and three Fabry-Perot interferometers (FPI) for a period exceeding 5 hours. From the southern hemisphere, a SDI at Mawson and a FPI at Davis, both in Antarctica, were geomagnetically mapped onto the northern hemisphere. These data were combined in the northern hemisphere with a SDI at Longyearbyen, Svalbard, and two FPIs near Kiruna in Sweden and Sodankyla in Finland. Geomagnetic conditions were moderate and steady although the IMF Bz did change polarity several times. There was good agreement between the conjugate 630 nm optical intensities and wind vectors. All wind field vectors were overlaid onto the northern SuperDARN ion convection contours. The agreement between neutral and ion flow was remarkably good throughout the study interval, even down to meso-scale spatial size.

Anderson, C.; Yiu, I.; Kellerman, A. C.; Kosch, M.; Makarevitch, R.; Aruliah, A. L.; Conde, M. G.; Davies, T.; Dyson, P. L.

2009-12-01

295

Controlling Compressor Vane Flow Vectoring Angles at Transonic Speeds  

NASA Astrophysics Data System (ADS)

The ability to control flow separation angles from compressor inlet guide vanes with a Coanda-type actuator is demonstrated using both wind tunnel experiments and finite element simulations. Vectoring angles up to 40 degrees from the uncontrolled baseline state were measured with helium schlieren visualization at transonic Mach numbers ranging from 0.1 to 0.6, and with airfoil chord Reynolds numbers ranging from 89,000 to 710,000. The magnitude of the vectoring angle is shown to depend upon the geometry of the trailing edge, and actuator slot size, and the momentum flux coefficient. Under certain conditions the blowing has no effect on the vectoring angle indicating that the Coanda effect is not present. DNS simulations with the finite element method investigated the effects of geometry changes and external flow. Continuous control of the vectoring angle is demonstrated, which has important implications for application to rotating machinery. The technique is shown to reduce the stall flow coefficient by 15 percent in an axial flow compressor.

Munson, Matthew; Rempfer, Dietmar; Williams, David; Acharya, Mukund

2003-11-01

296

Wind driven device and method of recovering wind energy  

SciTech Connect

A wind driven device for driving an electrical generator to produce electricity having a base, an anchor pole stationarily affixed to the base, and a drive assembly support rotatably mounted around the anchor pole. A plurality of gears engage the lower portion of the drive assembly support. The device also includes an upper exterior wind column support and a lower exterior wind column support. A plurality of attachment beams are connected to the drive assembly. A plurality of wind panel support columns connect to at least one of the attachment beams and to the upper and lower exterior support. A plurality of wind panels pivotally engage the wind panel support columns and is responsive to the wind such that the force of the wind against the wind panel causes the drive assembly support and the attached gears to revolve to provide for a power take off from the revolving gears to drive the electrical generator. A mobile wind panel angle selection guide is positioned around the drive assembly support to permit operation of the wind driven device when the direction of the wind changes. A method of recovering wind energy to drive an electrical generator to produce electricity having the steps of positioning the mobile wind panel angle selection guide around the drive assembly. A plurality of wind panels is mounted to the drive assembly to be guided by the mobile wind panel angle selection guide such that the force of the wind against the guided wind panels rotates the drive assembly which in turn causes the connected gears to operate the electrical generator. The position of the mobile wind panel guide is subsequently adjusted such that the force of the wind against any particular wind panel is a maximum when the particular wind panel is in a predetermined position with respect to the mobile wind panel angle selection guide.

Lanzrath, R.A.

1984-06-19

297

Operational cloud-motion winds from Meteosat infrared images  

SciTech Connect

The displacements of clouds in successive satellite images reflects the atmospheric circulation at various scales. The main application of the satellite-derived cloud-motion vectors is their use as winds in the data analysis for numerical weather prediction. At low latitudes in particular they constitute an indispensible data source for numerical weather prediction. This paper describes the operational method of deriving cloud-motion winds (CMW) from the IR images (10.5-12.5 [mu]m) of the European geostationary Meteosat satellites. The method is automatic, that is, the cloud tracking uses cross correlation and the height assignment is based on satellite observed brightness temperature and a forecast temperature profile. Semitransparent clouds undergo a height correction based on radiative forward calculations and simultaneous radiance observations in both the IR and water vapor (5.7-7.1 [mu]m) channel. Cloud-motion winds are subject to various quality checks that include manual quality controls as the last step. Typically about 3000 wind vectors are produced per day over four production cycles. This paper documents algorithm changes and improvements made to the operational CMWs over the last five years. The improvements are shown by long-term comparisons with both collocated radiosondes and the first guess of the forecast model of the European Centre for Medium-Range Weather Forecasts. In particular, the height assignment of a wind vector and radiance filtering techniques preceding the cloud tracking have ameliorated the errors in Meteosat winds. The slow speed bias of high-level CMWs (<400 hPa) in comparison to radiosonde winds has been reduced from about 4 to 1.3 m s[sup [minus]1] for a mean wind speed of 24 m s[sup [minus]1]. Correspondingly, the rms vector error of Meteosat high-level CMWs decreased from about 7.8 to 5 m s[sup [minus]1]. Medium-and low-level CMWs were also significantly improved. 56 refs., 12 figs., 2 tabs.

Schmetz, J.; Holmlund, K.; Mason, B.; Gaertner, V.; Koch, A.; Van De Berg, L. (European Space Agency, Darmstadt (Germany)); Hoffman, J. (METEO France, Toulouse (France)); Strauss, B. (European Centre for Medium-Range Weather Forecasts, Berkshire (United Kingdom))

1993-07-01

298

Pan evaporation and wind run decline in the Cape Floristic Region of South Africa (1974–2005): implications for vegetation responses to climate change  

Microsoft Academic Search

In many regions of the world, increasing temperatures in recent decades are paradoxically associated with declining pan evaporation,\\u000a but evidence is sparse for this trend from the southern hemisphere in general and sub-Saharan Africa in particular. In this\\u000a study, we examined changes in pan evaporation and four other meteorological variables (rainfall, wind run, temperature and\\u000a vapour pressure deficit) at 20

M. Timm Hoffman; Michael D. Cramer; Lindsey Gillson; Michael Wallace

2011-01-01

299

Change in the shoaling behaviour and nutritional condition of anchovies (Engraulis encrasicolus L.) during a wind-induced water column disturbance: a natural event test of a general hypothesis  

Microsoft Academic Search

Fishermen have long observed the sudden change of shoaling behaviour of small pelagic fish following a strong wind event. The phenomenon was thereafter confirmed by fisheries scientists using acoustic tools. In this study, we report our observations made with acoustics to measure disorganization of the previously observed spatial distribution and shape of shoals that occurred after a wind event. The

Jean-Pierre Bergeron; Jacques Massé

2011-01-01

300

Amazonian malaria: Asymptomatic human reservoirs, diagnostic challenges, environmentally-driven changes in mosquito vector populations, and the mandate for sustainable control strategies  

PubMed Central

Across the Americas and the Caribbean, nearly 561,000 slide-confirmed malaria infections were reported officially in 2008. The nine Amazonian countries accounted for 89% of these infections; Brazil and Peru alone contributed 56% and 7% of them, respectively. Local populations of the relatively neglected parasite P. vivax, which currently accounts for 77% of the regional malaria burden, are extremely diverse genetically and geographically structured. At a time when malaria elimination is placed on the public health agenda of several endemic countries, it remains unclear why malaria proved so difficult to control in areas of relatively low levels of transmission such as the Amazon Basin. We hypothesize that asymptomatic parasite carriage and massive environmental changes that affect vector abundance and behavior are major contributors to malaria transmission in epidemiologically diverse areas across the Amazon Basin. Here we review available data supporting this hypothesis and discuss their implications for current and future malaria intervention policies in the region. Given that locally generated scientific evidence is urgently required to support malaria control interventions in Amazonia, we briefly describe the aims of our current field-oriented malaria research in rural villages and gold-mining enclaves in Peru and a recently opened agricultural settlement in Brazil.

da Silva-Nunes, Monica; Moreno, Marta; Conn, Jan E.; Gamboa, Dionicia; Abeles, Shira; Vinetz, Joseph M.; Ferreira, Marcelo U.

2012-01-01

301

Winds of Change  

ERIC Educational Resources Information Center

|Five weeks after Katrina landed in Louisiana, Bonnabel and 78 other Jefferson Parish schools were welcoming students back--and far sooner than many had expected. The worst damage in Louisiana from Hurricane Katrina did not come to Jefferson Parish. That distinction was reserved for portions of New Orleans, as well as St. Bernard Parish, where…

Robelen, Erik W.

2005-01-01

302

Low level cloud motion vectors from Kalpana-1 visible images  

NASA Astrophysics Data System (ADS)

Till now low-level winds were retrieved using Kalpana-1 infrared (IR) images only. In this paper, an attempt has been made to retrieve low-level cloud motion vectors using Kalpana-1 visible (VIS) images at every half an hour. The VIS channel provides better detection of low level clouds, which remain obscure in thermal IR images due to poor thermal contrast. The tracers are taken to be 15 × 15 pixel templates and hence each wind corresponds to about 120 km × 120 km at sub-satellite point. Multiplet based wind retrieval technique is followed for VIS wind derivation. However, for height assignment of VIS winds, collocated IR image is used. Due to better contrast between cloud and ocean surface, the low level atmospheric flow is captured better as compared to IR winds. The validation of the derived VIS winds is done with Global Forecast System (GFS) model winds and Oceansat-II scatterometer (OSCAT) winds.

Kaur, Inderpreet; Deb, S. K.; Kishtawal, C. M.; Pal, P. K.; Kumar, Raj

2013-08-01

303

Vector Addition Model  

NSDL National Science Digital Library

The Vector Addition model allows the user to practice vector addition of two vectors in two dimensions. You are given the magnitude and direction of the two vectors, and your goal is to fill in the nine values in the table (showing the x-component, y-component, and length) of the two vectors, and the resultant vector that is the sum of the first two vectors. The Vector Addition was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_bu_vector_addition.jar file will run the program if Java is installed.

Duffy, Andrew

2010-04-25

304

Experimental investigation of change of energy of infragavity waves in dependence on spectral characteristics of an irregular wind waves in coastal zone  

NASA Astrophysics Data System (ADS)

An infragravity waves are long waves with periods of 20 - 300 s. Most essential influence of infragarvity waves on dynamic processes is in a coastal zone, where its energy can exceed the energy of wind waves. From practical point of view, the infragravity waves are important, firstly, due to their influence on sand transport processes in a coastal zone. For example, interacting with group structure of wind waves the infragravity waves can define position of underwater bars on sandy coast. Secondly, they are responsible on formation of long waves in harbors. Main source of infragravity waves is wave group structure defined by sub-nonlinear interactions of wind waves (Longuet-Higgins, Stewart, 1962). These infragravity waves are bound with groups of wind waves and propagate with wave group velocity. Another type of infragravity waves are formed in a surf zone as a result of migration a wave breaking point (Symonds, et al., 1982). What from described above mechanisms of formation of infragravity waves prevails, till now it is unknown. It is also unknown how energy of infragravity waves depends on energy of input wind waves and how it changes during nonlinear wave transformation in coastal zone. In our work on the basis of the analysis of data of field experiment and numerical simulation a contribution of infragravity waves in total wave energy in depending on integral characteristics of an irregular wave field in the conditions of a real bathymetry was investigated. For analysis the data of field experiment "Shkorpilovtsy-2007" (Black sea) and data of numerical modeling of Boussinesq type equation with extended dispersion characteristics (Madsen et al., 1997) were used. It was revealed that infragravity waves in a coastal zone are defined mainly by local group structure of waves, which permanently changes due to nonlinearity, shoaling and breaking processes. Free infragravity waves appearing after wave breaking exist together with bound infragravity waves. There are no clear total dependences of energy of infrragravity waves from energy of wind waves and mean period of infragravity waves from mean period of wind waves. But significant wave height of infragravity waves depends on relative water depth (wave height of wind waves divided on water depth). There are different types of this dependence for breaking and non-breaking waves. The influence of peak period, significant wave height and directional spreading of initial wave spectrum on these dependences are discussed. The peculiarities of spectra of infragravity waves for non-breaking, breaking and multibreaking wind waves are shown. This work is supported by the RFBR, project 12-05-00965. References: Longuet-Higgins, M. S., R. W. Stewart, 1962. Radiation stress and mass transport in gravity waves, with an application to surf beats. J. Fluid Mech., 13, pp. 481-504. Symonds G., D.A. Huntley, A.J. Bowen, 1982. Two dimensional surf beat: long wave generation by a time-varying breakpoint. J. of Geoph. Res., 87(C), pp.492-498. Madsen P.A., Sorensen O.R., Shaffer H.A. 1997. Surf zone dynamics simulated by a Boussinesq type model. Coastal Engineering, 32, p. 255-287.

Saprykina, Yana; Divinskii, Boris

2013-04-01

305

Comparison of the response of doubly fed and fixed-speed induction generator wind turbines to changes in network frequency  

Microsoft Academic Search

Synchronous and fixed-speed induction generators release the kinetic energy of their rotating mass when the power system frequency is reduced. In the case of doubly fed induction generator (DFIG)-based wind turbines, their control system operates to apply a restraining torque to the rotor according to a predetermined curve with respect to the rotor speed. This control system is not based

J. Ekanayake; N. Jenkins

2004-01-01

306

Changes in sea-level pressure over South Korea associated with high-speed solar wind events  

NASA Astrophysics Data System (ADS)

We explore a possibility that the daily sea-level pressure (SLP) over South Korea responds to the high-speed solar wind event. This is of interest in two aspects: first, if there is a statistical association this can be another piece of evidence showing that various meteorological observables indeed respond to variations in the interplanetary environment. Second, this can be a very crucial observational constraint since most models proposed so far are expected to preferentially work in higher latitude regions than the low latitude region studied here. We have examined daily solar wind speed V, daily SLP difference ?SLP, and daily log(BV2) using the superposed epoch analysis in which the key date is set such that the daily solar wind speed exceeds 800 km s-1. We find that the daily ?SLP averaged out of 12 events reaches its peak at day +1 and gradually decreases back to its normal level. The amount of positive deviation of ?SLP is +2.5 hPa. The duration of deviation is a few days. We also find that ?SLP is well correlated with both the speed of solar wind and log(BV2). The obtained linear correlation coefficients and chance probabilities with one-day lag for two cases are r ? 0.81 with P > 99.9%, and r ? 0.84 with P > 99.9%, respectively. We conclude by briefly discussing future direction to pursue.

Cho, Il-Hyun; Kwak, Young-Sil; Marubashi, Katsuhide; Kim, Yeon-Han; Park, Young-Deuk; Chang, Heon-Young

2012-09-01

307

Winds over Japan  

Microsoft Academic Search

Before World War II, weather forecasters had little knowledge of upper-air wind patterns above 20000 feet. Data were seldom avai able at these heights, and the need was not great because commercial aircraft seldom flew at these altitudes. The war in the Pacific changed all that. Wind forecasts for 30000 feet plus became urgent to support the XXI Bomber Command

William J. Plumley

1994-01-01

308

Comparison of analyzed and measured wind speeds in the perspective of oceanic simulations over the Mediterranean basin: Analyses, QuikSCAT and buoy data  

Microsoft Academic Search

Surface vector wind datasets from different assimilation systems and from scatterometers have been recently made available over the entire Mediterranean basin and for a large spectrum of spatial and temporal resolution. In this work, we compare wind vector analyses, derived from different routine assimilation systems and from blended products, to wind vectors obtained from QuikSCAT satellite sensor and to those

Paolo M. Ruti; Salvatore Marullo; Fabrizio D'Ortenzio; Michel Tremant

2008-01-01

309

Association of Anthropogenic Land Use Change and Increased Abundance of the Chagas Disease Vector Rhodnius pallescens in a Rural Landscape of Panama  

PubMed Central

Anthropogenic disturbance is associated with increased vector-borne infectious disease transmission in wildlife, domestic animals, and humans. The objective of this study was to evaluate how disturbance of a tropical forest landscape impacts abundance of the triatomine bug Rhodnius pallescens, a vector of Chagas disease, in the region of the Panama Canal in Panama. Rhodnius pallescens was collected (n = 1,186) from its primary habitat, the palm Attalea butyracea, in five habitat types reflecting a gradient of anthropogenic disturbance. There was a high proportion of palms infested with R. pallescens across all habitat types (range = 77.1–91.4%). Results show that disturbed habitats are associated with increased vector abundance compared with relatively undisturbed habitats. Bugs collected in disturbed sites, although in higher abundance, tended to be in poor body condition compared with bugs captured in protected forest sites. Abundance data suggests that forest remnants may be sources for R. pallescens populations within highly disturbed areas of the landscape.

Gottdenker, Nicole L.; Calzada, Jose E.; Saldana, Azael; Carroll, C. Ronald

2011-01-01

310

Using incoherent scatter radar to investigate the neutral wind long-term trend over Arecibo  

NASA Astrophysics Data System (ADS)

Thermospheric neutral winds can be the most important driver when modeling ionospheric densities and temperatures. Several papers in this special edition show interesting features of the neutral winds behavior during the last 30 years at the Arecibo Observatory (18.3°N, 66.75°W ˜28.25° dip latitude) using Fabry-Perot Interferometer (FPI) data. A neutral wind vector that changes its direction, becoming more dominantly eastward over the years and a meridional neutral wind component that decreases in magnitude, were found. The main goal of this work is to look for similar evidence of long-term trends in the radar derived winds that might support these recent discoveries and explore the associated ionospheric parameter measurements to look for the effects of these changing winds on the ionosphere. With this purpose in mind, Incoherent Scatter Radar (ISR) measurements of the F region vector drifts are used to derive the corresponding meridional thermospheric neutral wind along the magnetic field over Arecibo during 20 years. Major findings include a decreasing long-term trend (lowering) of the height where the F2- layer peak density occurs (hmF2), which could be related with a more increased downward flux of the ionosphere. A slight decrease in the peak density of the F2- layer (NmF2) after local midnight also was found during the period studied. The meridional wind along the magnetic field derived from ISR data also revealed a long-term trend, becoming more northward during the period studied, with a maximum variation between 02:30UT and 05:30UT.

Santos, P. T.; Brum, C. G. M.; Tepley, C. A.; Aponte, N.; González, S. A.; Robles, E.

2011-11-01

311

Observed near-surface currents under high wind speeds  

NASA Astrophysics Data System (ADS)

From the Surface Velocity Program (SVP) drifter current and QuikSCAT wind data, the relationship between the observed near-surface current vectors and surface wind vectors for the northwestern Pacific Ocean under high winds (20-50 m s-1) are obtained with quantitative estimations of near-surface drift ratio (current speed versus wind speed)r(˜2%) and near-surface drift angle? (˜0°-10° to the right of the winds). These estimations keep unchanged after removing the surface geostrophic component. From the SVP drifter current and daily WindSat wind data, the estimated ris still approximately 2%. Three linear regression equations are obtained between the observed near-surface current speeds and the surface wind stress for the high wind range.

Chang, Y.-C.; Chen, G.-Y.; Tseng, R.-S.; Centurioni, L. R.; Chu, Peter C.

2012-11-01

312

Spacebased estimation of moisture transport in marine atmosphere using support vector regression  

Microsoft Academic Search

An improved algorithm is developed based on support vector regression (SVR) to estimate horizonal water vapor transport integrated through the depth of the atmosphere (?) over the global ocean from observations of surface wind-stress vector by QuikSCAT, cloud drift wind vector derived from the Multi-angle Imaging SpectroRadiometer (MISR) and geostationary satellites, and precipitable water from the Special Sensor Microwave\\/Imager (SSM\\/I).

Xiaosu Xie; W. Timothy Liu; Benyang Tang

2008-01-01

313

Spatial modelling of the potential temperature-dependent transmission of vector-associated diseases in the face of climate change: main results and recommendations from a pilot study in Lower Saxony (Germany).  

PubMed

The sustained climate change is going to modify the geographic distribution, the seasonal transmission gate and the intensity of the transmission of vector-borne diseases such as malaria or the bluetongue disease. These diseases occur nowadays at higher latitudes or altitudes. A further rise in ambient temperature and rainfall will extend the duration of the season in which mosquito vectors are transmitting pathogens. The parasites transmitted by the vectors also benefit from increasing temperatures, as both their reproduction and development are then accelerated, too. Thus, it seemed prudent to examine potential effects on the seasonal transmission gate due to the ongoing and predicted climate changes. Lower Saxony (northwest Germany) is a former malaria region with highest incidences of Anopheles atroparvus and tertian malaria along the coastal zones before malaria had finally become extinct in the early 1950s. Nevertheless, the Anopheles mosquitoes which transmit the malaria pathogens have still been present in Lower Saxony up to now. This together with the climate change-related implications gave reason to investigate whether a new autochthonous transmission could take place if the malaria pathogen is introduced again in Lower Saxony. Thus, the potential spatial and temporal structure of temperature-driven malaria transmissions was mapped using the basic reproduction rate (R (0)) and measured and predicted air temperatures (1947-1960, 1961-1990, 1985-2004, 2020, 2060, 2100, each best case and worst case scenario). This paper focuses on both the summarizing of the results from this risk modelling approach and on the conclusions to be drawn. The recommendations highlight the need to link vector monitoring as one of the key elements of an epidemiological monitoring with the environmental monitoring. PMID:19030886

Schröder, Winfried; Schmidt, Gunther

2008-11-23

314

Application of satellite surface wind data to ocean wind analysis  

NASA Astrophysics Data System (ADS)

A new set of cross-calibrated, multi-satellite ocean surface wind data is described. The principal data set covers the global ocean for the period beginning in 1987 with six-hour and 25-km resolution, and is produced by combining all ocean surface wind speed observations from SSM/I, AMSR-E, and TMI, and all ocean surface wind vector observations from QuikSCAT and SeaWinds. An enhanced variational analysis method (VAM) performs quality control and combines these data with available conventional ship and buoy data and ECMWF analyses. The VAM analyses fit the data used very closely and contain small-scale structures not present in operational analyses. Comparisons with withheld WindSat observations are also shown to be very good. These data sets should be extremely useful to atmospheric and oceanic research, and to air-sea interaction studies.

Atlas, Robert; Ardizzone, Joseph; Hoffman, Ross N.

2008-08-01

315

Significant changes in systolic blood pressure post vectored upper cervical adjustment vs resting control groups: A possible effect of the cervicosympathetic and\\/or pressor reflex  

Microsoft Academic Search

Objective: To determine whether a vectored adjustment of the atlas in patients identified as demonstrating signs of upper cervical joint dysfunction would cause lowering of blood pressure in comparison with resting controls. Design: Test 1: controlled clinical trial with a treatment (adjustment) group and a control (resting) group. Test 2: controlled clinical trial with subjects serving as their own controls.

Gary A. Knutson

2001-01-01

316

Extratropical Cyclones With Hurricane Force Winds  

Microsoft Academic Search

The NASA QuikSCAT scatterometer provides near global coverage of ocean surface vector winds each day. The combined coverage of the QuikSCAT instrument and high retrievable wind range to 40 m s-1 or more in non-raining conditions has revolutionized the high seas warning and short-term forecast process at the NOAA Ocean Prediction Center (OPC). OPC forecasters routinely see the wind field

J. M. Sienkiewicz; M. J. Brennan; J. M. von Ahn; S. G. Winterberger

2008-01-01

317

SWE, a comprehensive plasma instrument for the WIND spacecraft  

Microsoft Academic Search

The Solar Wind Experiment (SWE) on the WIND spacecraft is a comprehensive, integrated set of sensors which is designed to investigate outstanding problems in solar wind physics. It consists of two Faraday cup (FC) sensors; a vector electron and ion spectrometer (VEIS); a strahl sensor, which is especially configured to study the electron ‘strahl’ close to the magnetic field direction;

K. W. Ogilvie; D. J. Chornay; R. J. Fritzenreiter; F. Hunsaker; J. Keller; J. Lobell; G. Miller; J. D. Scudder; E. C. Sittler; R. B. Torbert; D. Bodet; G. Needell; A. J. Lazarus; J. T. Steinberg; J. H. Tappan; A. Mavretic; E. Gergin

1995-01-01

318

Wind power  

Microsoft Academic Search

The fundamentals of wind power utilization are described with emphasis placed on the information needed to determine the basic geometry of wind power devices and to discuss the availability of wind for power generation. The economics and social acceptance of wind power systems at the present time are analyzed.

G. M. Bragg

1979-01-01

319

Offshore Wind Power Integration in severely fluctuating Wind Conditions  

NASA Astrophysics Data System (ADS)

Strong power fluctuations from offshore wind farms that are induced by wind speed fluctuations pose a severe problem to the save integration of offshore wind power into the power supply system. Experience at the first large-scale offshore wind farm Horns Rev showed that spatial smoothing of power fluctuations within a single wind farm is significantly smaller than onshore results suggest when distributed wind farms of 160 MW altogether are connected to a single point of common-coupling. Wind power gradients larger than 10% of the rated capacity within 5 minutes require large amount of regulation power that is very expensive for the grid operator. It must be noted that a wind speed change of only 0.5m/s result in a wind power change of 10% (within the range of 9-11 m/s where the wind power curve is steepest). Hence, it is very important for the grid operator to know if strong fluctuations are likely or not. Observed weather conditions at the German wind energy research platform FINO1 in the German bight are used to quantify wind fluctuations. With a standard power curve these wind fluctuations are transfered to wind power. The aim is to predict the probability of exceedence of certain wind power gradients that occur in a time interval of e.g. 12 hours. During 2006 and 2009 the distribution of wind power fluctuations looks very similar giving hope that distinct atmospheric processes can be determined that act as a trigger. Most often high wind power fluctuations occur in a range of wind speeds between 9-12 m/s as can be expected from the shape of the wind power curve. A cluster analysis of the 500 hPa geopotential height to detect predominant weather regimes shows that high fluctuations are more likely in north-western flow. It is shown that most often high fluctuations occur in non-stable atmospheric stratification. The description of stratification by means of the vertical gradient of the virtual potential temperature is chosen to be indicative for convection, i.e. it can be assumed that a negative gradient indicates convection which leads to strong wind fluctuations in the updraft and downdraft of the cloud. Neural Networks are used to determine the probability of exceedence of wind power gradients from a set of atmospheric parameters that are taken from Numerical Weather Prediction Models. Parameters describing atmospheric stability, that are related to convection (e.g. rain rate) and that forecast wind gusts tend to carry most information to estimate expected wind power fluctuations.

von Bremen, L.

2010-09-01

320

Cusp/cleft auroral forms and activities in relation to ionospheric convection: Responses to specific changes in solar wind and interplanetary magnetic field conditions  

SciTech Connect

The authors describe in detail a four hour period on Dec 17, 1992, of cusp/cleft region observations, made in conjunction with the occurance of a transient auroral event. There was an IMF directional discontinuity where the fields changed from positive IMF B{sub y} (B{sub z}{much_lt}0) to large negative B{sub y} (B{sub z}>0) in conjunction with a change in convection direction in the cusp region. They present data from satellite observations, in addition to ground based data collected over an array of stations in Greenland and Svalbard. They view this as a first step toward an effort to correlate responses in the ionosphere to different solar wind and interplantetary magnetic field conditions. They analyze this data in terms of the array of different conditions which was exhibited in the ionosphere over this four hour period.

Sandholt, P.E. [Univ., of Oslo, Oslo (Norway); Farrugia, C.J. [Univ. of Malta, Msida (Malta); Stauning, P. [Danish Meteorological Institute, Copenhagen (Denmark); Crowley, S.W.H. [Imperial College, London (United Kingdom)

1996-03-01

321

Balance of Forces with the Wind (title provided or enhanced by cataloger)  

NSDL National Science Digital Library

This applet tests the balance of the frictional, pressure gradient, and Coriolis forces with the wind. The applet displays vectors for these forces and the wind as the latitude, friction (drag), and pressure gradient are adjusted.

Ackerman, Steve; Whittaker, Tom

322

Directional trends in thermospheric neutral winds observed at Arecibo during the past three solar cycles  

Microsoft Academic Search

Thermospheric neutral winds at Arecibo show a long-term trend over timeThe vector magnitude of the wind increased slightly and its direction rotated CCWDecreases in neutral density\\/temperature and ion coupling help explain trends

C. A. Tepley; E. Robles; R. García; P. T. Santos; C. M. Brum; R. G. Burnside

2011-01-01

323

Efficient transfer of base changes from a vector to the rice genome by homologous recombination: involvement of heteroduplex formation and mismatch correction  

Microsoft Academic Search

Gene targeting refers to the alteration of a specific DNA sequence in an endogenous gene at its original locus in the genome by homologous recombination. Through a gene-targeting procedure with positive- negative selection, we previously reported the generation of fertile transgenic rice plants with a positive marker inserted into the Adh2 gene by using an Agrobacterium-mediated transformation vector containing the

Yasuyo Johzuka-Hisatomi; Rie Terada; Shigeru Iida

2008-01-01

324

Male stable fly (Stomoxys calcitrans) response to CO2 changes with age: evidence from wind tunnel experiments and field collections.  

PubMed

Male stable flies require at least one or more blood meals to reach sexual maturity and are often caught in CO2-baited traps. We tested the hypothesis that young male stable flies (one to three days, one blood feeding session) would be more responsive to CO2 bait than older male stable flies by monitoring the upwind movement of different-aged male stable flies exposed to CO2 using a wind tunnel. The proportion of males moving upwind toward CO2 decreased with age (days), from 49% for males < or = 3 days old, to 4.5% for males > 3 days old. To further test this, we conducted daily sampling of stable fly populations at a beef farm using a CO2-baited cloth trap. We found that days on which a high proportion of males were caught, females were predominantly from early developmental stages, indicating that proportionately more males were caught from field populations made up of younger cohorts. These results were consistent with the wind tunnel experiment patterns. PMID:19263843

Beresford, D V; Sutcliffe, J F

2008-12-01

325

A Mathematical Model for Diagnosis and Prediction of Surface Winds in Mountainous Terrain  

Microsoft Academic Search

Many mechanisms and factors are responsible for winds in mountainous areas. A mathematical model was developed on the premise that mountain winds are the result of vector addition of wind components generated and modified by these influences. The functions and techniques used in the model were formulated to define and integrate such components of the resultant wind in mountainous areas

Bill C. Ryan

1977-01-01

326

Vector-valued wavelets and vector filter banks  

Microsoft Academic Search

In this paper, we introduce vector-valued multiresolution analysis and vector-valued wavelets for vector-valued signal spaces. We construct vector-valued wavelets by using paraunitary vector filter bank theory. In particular, we construct vector-valued Meyer wavelets that are band-limited. We classify and construct vector-valued wavelets with sampling property. As an application of vector-valued wavelets, multiwavelets can be constructed from vector-valued wavelets. We show

Xiang-Gen Xia; B. W. Suter

1996-01-01

327

Origin of Titan's dunes: noncohesive sand in bidirectional winds or sticky sand in unidirectional winds?  

NASA Astrophysics Data System (ADS)

Eolian dunes occur on Earth, Venus, Mars, and Titan, distinguishing them as one of the more widespread landforms in the solar system. On Earth, unidirectional winds blowing over loose, noncohesive sand produce crescentic-shaped dunes with crests oriented normal to the sand-transport direction (transverse dunes), but roughly half of Earth's large deserts are covered with longer-crested dunes (linear dunes) that are commonly oriented parallel or oblique to the resultant sand-transport vector (longitudinal dunes and oblique dunes, respectively). Such linear dunes form in at least two situations: (1) directionally bimodal winds blowing over loose sand, and (2) unimodal winds blowing over sediment that is vegetated, cohesive, sheltered by upwind topography, or otherwise locally stabilized. This study documents an example (Qaidam Basin, China) where a downwind increase in sediment cohesiveness (due to salt and mud incorporated from the local land surface) causes dunes to change orientation from transverse to longitudinal, and the work presents a compilation of related situations where stabilization of dune sediment has been reported to produce linear dunes. This family of stabilized dunes functions dynamically as self-extending "sand-shadow" or lee dunes. Loose sediment accumulates locally on these dunes, where it becomes stabilized, thereby allowing the dune itself to function as an obstacle that induces subsequent deposition farther downwind. Linear dunes on Titan previously have been interpreted as forming in the first situation listed above: bimodal winds blowing over loose sand. Because Titan's sand is believed to be composed of hydrocarbons or nitriles, however, the hypothesized loose, non-sticky nature of the sand has surprised researchers. In addition, the previous hypothesis of bimodal winds requires that north-south tidal flow be stronger than west-east zonal flow, which also was unexpected. The new hypothesis presented here—that Titan's dunes formed by unidirectional winds blowing over cohesive or sticky sand—resolves these two puzzles, cannot be ruled out with existing observations, and has grossly different implications regarding Titan's sediment properties, surface moisture, and wind regime. Satellite image of dunes in the Qaidam Basin, China. Change in sediment properties causes a change from transverse to longitudinal orientation of the dunes. Transverse dunes are higher in elevation than the longitudinal dunes and composed of noncohesive sand. Longitudinal dunes are cemented with silt, clay, and salt acquired locally.

Rubin, D. M.

2009-12-01

328

Vector Addition Patterns Model  

NSDL National Science Digital Library

The Vector Addition Patterns model illustrates the tail-to-tip method of adding vectors. The table at the bottom shows the components and lengths of the vectors. You can also rotate the vectors and trace out some interesting patterns. The Vector Addition Patterns model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_bu_vector_addition_patterns.jar file will run the program if Java is installed.

Duffy, Andrew

2010-05-02

329

Numerical Calculations of Wind Flow in a Full-Scale Wind Test Facility  

SciTech Connect

Numerical studies on wind flow around the Texas Tech University (TTU) Wind Engineering Research Field Laboratory (WERFL) building were conducted. The main focus of this paper is wind loads on the TTU building in the INEEL proposed Windstorm Simulation Center. The results are presented in the form of distributions of static pressure, dynamic pressure, pressure coefficients, and velocity vectors on the surface and the vicinity of the TTU building.

Oh, Chang H; Lacey, Jerry Mark

1999-06-01

330

Numerical calculations of wind flow in a full-scale wind test facility  

SciTech Connect

Numerical studies on wind flow around the Texas Tech University (TTU) Wind Engineering Research Field Laboratory (WERFL) building were conducted. The main focus of this paper is wind loads on the TTU building in the INEEL proposed Windstorm Simulation Center. The results are presented in the form of distributions of static pressure, dynamic pressure, pressure coefficients, and velocity vectors on the surface and the vicinity of the TTU building.

C.H. Oh; J.M. Lacey

1999-06-20

331

Wind Energy  

NSDL National Science Digital Library

Students learn about wind energy by making a pinwheel to model a wind turbine. Just like engineers, they decide where and how their turbine works best by testing it in different areas of the playground.

Integrated Teaching And Learning Program

332

Wind Energy  

Microsoft Academic Search

\\u000a The kinetic energy of wind is harvested using wind turbines to generate electricity. Among various renewable energy sources,\\u000a wind energy is the second most technologically advanced renewable energy source; hydropower is the first. Although there is\\u000a a significant potential for converting wind energy to electricity, a number of issues must be addressed before it can be used\\u000a to its full

Tushar K. Ghosh; Mark A. Prelas

333

Vector Components Model  

NSDL National Science Digital Library

The Vector Components model allows the user to split a vector into its components, and practice finding the magnitude and direction of a vector if you know the components. In the "Find components" mode, you are given the magnitude and direction of the vector, and your goal is to find the x-component and the y-component of the vector. In the "Find magnitude and direction" mode, you are given the two components, and you need to find the magnitude and direction of the vector. The Vector Components was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_bu_vector_components.jar file will run the program if Java is installed.

Duffy, Andrew

2010-04-27

334

Wind energy  

Microsoft Academic Search

The 1972 Solar Energy Panel of NASA and the National Science Foundation estimated the potential wind power available in the U.S. to be about 100,000 gigawatts, which is 30 times greater than the projected energy consumption for 1980. Wind energy is discussed with a view of providing a practical foundation and guide to the analysis and application of wind energy

B. Wolff; H. Meyer

1978-01-01

335

Vector control in developed countries  

PubMed Central

The recent rapid growth of California's population, leading to competition for space between residential, industrial and agricultural interests, the development of its water resources and increasing water pollution provide the basic ingredients of its present vector problems. Within the past half-century, the original mosquito habitats provided by nature have gradually given place to even more numerous and productive habitats of man-made character. At the same time, emphasis in mosquito control has shifted from physical to chemical, with the more recent extension to biological approaches as well. The growing domestic fly problem, continuing despite the virtual disappearance of the horse, is attributable to an increasing amount of organic by-products, stemming from growing communities, expanding industries and changing agriculture. The programme for the control of disease vectors and pest insects and animals directs its major effort to the following broad areas: (1) water management (including land preparation), (2) solid organic wastes management (emphasizing utilization), (3) community management (including design, layout, and storage practices of buildings and grounds), and (4) recreational area management (related to wildlife management). It is apparent that vector control can often employ economics as an ally in securing its objectives. Effective organization of the environment to produce maximum economic benefits to industry, agriculture, and the community results generally in conditions unfavourable to the survival of vector and noxious animal species. Hence, vector prevention or suppression is preferable to control as a programme objective.

Peters, Richard F.

1963-01-01

336

Multiphase space vector pulse width modulation  

Microsoft Academic Search

Pole-phase modulation adjusts the pole-phase ratio of an induction machine and requires a multileg, multiphase inverter. This paper analyzes an n-leg, n-phase inverter, and presents techniques for n-phase space vector pulse width modulation (SVPWM). In particular, nine-phase SVPWM is developed and implemented on a nine winding induction machine. The nine-phase SVPWM is compared to nine phase sine-triangle PWM in terms

John W. Kelly; Elias G. Strangas; John M. Miller

2003-01-01

337

Shearing wind helicity and thermal wind helicity  

NASA Astrophysics Data System (ADS)

Helicity is defined as H = V . omega, where V and omega are the velocity and vorticity vectors, respectively. Many works have pointed out that the larger the helicity is, the longer the life cycle of the weather system is. However, the direct relationship of the helicity to the evolution of the weather system is not quite clear. In this paper, the concept of helicity is generalized as shearing wind helicity (SWH). Dynamically, it is found that the average SWH is directly related to the increase of the average cyclonic rotation of the weather system. Physically, it is also pointed out that the SWH, as a matter of fact, is the sum of the torsion terms and the divergence term in the vorticity equation. Thermal wind helicity (TWH), as a derivative of SWH, is also discussed here because it links the temperature field and the vertical wind field. These two quantities may be effective for diagnosing a weather system. This paper applies these two quantities in cylindrical coordinates to study the development of Hurricane Andrew to validate their practical use. Through analyzing the hurricane, it is found that TWH can well describe the characteristics of the hurricane such as the strong convection and release of latent heat. SWH is not only a good quantity for diagnosing the weather system, but also an effective one for diagnosing the development of the hurricane.

Han, Y.; Wu, R. S.; Fang, J.

2006-07-01

338

Climatology of extreme winds in southern California  

SciTech Connect

A climatology of annual extreme winds in southern California has been prepared. The climatology includes a description of extreme wind regions, defined on the basis of observed winds and topography. Extreme wind distribution parameters have been estimated for 46 locations using data obtained from the National Climatic Data Center. Probabilities associated with extreme winds have been estimated for these locations. The results of the analysis are generally consistent with previous estimates of extreme winds in southern California. Although in several instances the current estimates are significantly higher than previous estimates. The data examined do not indicate that there has been a significant change in the extreme wind climate of southern California.

Ramsdell, J.V.; Hubbe, J.M.; Elliott, D.L.; Holladay, C.G.

1987-01-01

339

Wind Turbines Adaptation to the Variability of the Wind Field  

NASA Astrophysics Data System (ADS)

WIND TURBINES ADAPTATION TO THE VARIABILITY OF THE WIND FIELD The subject of our scientific research is wind power turbines (WPT) with the horizontal axis which were now common in the world. Efficient wind turbines work is largely determined by non-stationarity of the wind field, expressed in its gustiness, the presence of vertical and horizontal shifts of wind speed and direction. At critical values of the wind parameters WPT has aerodynamic and mechanical overload, leading to breakdowns, premature wear and reduce the life of the wind turbine. To prevent accidents at the peak values of wind speed it is used the regulatory system of windwheels. WPT control systems provide a process orientation of the wind turbine rotor axis in the line of the mean wind. Wind turbines are also equipped with braking device used to protect against breakdowns when a significant increase in the wind. In general, all these methods of regulation are not always effective. Thus, in practice there may be situations when the wind speed is many times greater than the stated limit. For example, if there are microbursts in the atmospheric boundary layer, low-level wind shears caused by its gust front, storms, etc. It is required for a wind power turbine adaptation to intensive short-term wind impulses and considerable vertical wind shifts that the data about them shall be obtained ahead of time. To do this it is necessary to have the information on the real structure of the wind field in the area of the blade sweep for the minimum range against the wind that is determined by the mean speed and the system action time. The implementation of acoustic and laser traditional wind sounding systems is limited by ambient acoustic noise, by heavy rain, snowfall and by fog. There are free of these disadvantages the inclined radioacoustic sounding (IRASS) technique which works for a system of remote detection and control of wind gusts. IRASS technique is realized as low-potential Doppler pulse radar including combined RF-acoustic antenna installed coaxially with the gondola of the wind power turbine. The work of the technique is synchronized with rotation of blades to eliminate their shielding action. Dangerous in terms of dynamic strength is the wind load pulse, the rise time which is comparable with the period of the natural frequency of the wind turbine elements (blade, tower, rotor, etc.). The amplitude decay of resonant vibrations at critical values of the speed of rotation can be realized through the use of mechanical elastic supports with nonlinear artificial dampers. They have a high coefficient of resistance, but may cause self-excited oscillations. We propose the way to deal with raised vibration of wind turbine elements at the expense of short-term increase of damping in the range of critical rotary axis speeds or during impulsive effects of wind loadings (wind gusts). This is possible through the use of non-linear electromagnetic dampers or active magnetic bearings. Their feature is the possibility of varying the mechanical stiffness and damping properties by changing the electrical parameters of electromagnets. The controlling of these parameters is carried out by the control system (CS) with the information feedback on the spatial-temporal structure of the wind field obtained from IRASS. In the composition of the CS can also be included the rotational speed sensor of the WPT rotor. This approach to the adaptation of wind turbines will allow to reduce vibration and to perform early compensation of the load on their components, which arise under the wind gusts. In addition, corrections about the wind field obtained with IRASS, would increase the mean power of WPT.

Ulianov, Yuriy; Martynenko, Gennadii; Misaylov, Vitaliy; Soliannikova, Iuliia

2010-05-01

340

Rhotrix Vector Spaces  

ERIC Educational Resources Information Center

|By rhotrix we understand an object that lies in some way between (n x n)-dimensional matrices and (2n - 1) x (2n - 1)-dimensional matrices. Representation of vectors in rhotrices is different from the representation of vectors in matrices. A number of vector spaces in matrices and their properties are known. On the other hand, little seems to be…

Aminu, Abdulhadi

2010-01-01

341

Nonviral Vector Systems  

Microsoft Academic Search

Gene therapy requires efficient vectors for delivering therapeutic genes. Advances in developments of nonviral vectors have\\u000a been established for improving the efficiency of gene delivery. This chapter describes different nonviral methods as well\\u000a as their applications. Some new directions in developing nonviral vectors are also discussed.

Pui-yan Lee; Leaf Huang

342

Asymptotic Code Vector Density in Topographic Vector Quantizers.  

National Technical Information Service (NTIS)

A noise robust vector quantizer model is used to derive expressions for the asymptotic code vector density in various types of topographic vector quantizers. A topographic vector quantizer is not identical to a standard (i.e., Kohonen) topographic mapping...

S. P. Luttrell

1990-01-01

343

Tropical Winds in the Stratosphere from HRDI (1991-1996)  

NSDL National Science Digital Library

The High Resolution Doppler Interferometer (HRDI) measures winds in both the stratosphere and mesosphere. The tropical winds in the stratosphere undergo a slow two year variation called the quasibianunual oscillation. This oscillation controls mixing throughout the stratosphere and HRDI has given us much detail on wind changes associated with this oscillation. The animation indicates the line of zero wind speed in the zonal tropical winds, the height at which the winds change from eastward to westward.

Shirah, Greg; Schoeberl, Mark

1999-04-09

344

Effect of Coflow on Counterflow Thrust Vectoring  

NASA Astrophysics Data System (ADS)

A unique, fluidic-based thrust vectoring technique known as CounterFlow Thrust Vector Control (CFTVC) has been investigated at the Fluid Mechanics Research Laboratory (FMRL) over the past few years. These studies have demonstrated that CFTVC is a simple, robust and efficient method for thrust vectoring of supersonic jets of various geometries. In an effort to better evaluate the system performance under real flight conditions, a study of the CFTVC system under "wind-on" conditions, using a rectangular Mach 1.4 jet, is currently in progress. The wind-on condition is simulated by providing a coflowing stream (i.e. flowing in the same direction as the primary jet) at the periphery of the countercurrent stream which surrounds the primary jet. Coflowing streams over a range of Mach numbers, from 0.3 to 0.7, will be tested. Preliminary results show that the coflowing stream has a relatively minor influence on CFTVC and that the jet can be easily vectored to large angles in the presence of coflow. These encouraging reuslts further demonstrate the potential of this system for future propulsion applications.

Alvi, F. S.; Krothapalli, A.; Strykowski, P. J.

1997-11-01

345

Cedar Fortran and other Vector and parallel Fortran dialects  

Microsoft Academic Search

The introduction of vector processors and multiprocessors punctuate the most dramatic changes in Fortran and its dialects. The emerging generation of supercomputers utilize both vector processing and multiprocessing simultaneously. The challenge is to provide language constructs and software tools that will allow the programmer to easily exploit the capabilities of the machine.This paper will outline the development of vector and

Mark D. Guzzi; Jay Hoeflinger; David A. Padua; Duncan H. Lawrie

1988-01-01

346

Cedar Fortran and other vector and parallel Fortran dialects  

Microsoft Academic Search

The introduction of vector processors and multiprocessors has caused the most dramatic changes in Fortran and its dialects. The emerging generation of supercomputers utilizes both vector processing and multiprocessing. The challenge is to provide language constructs and software tools that will allow the programmer to easily exploit the capabilities of the machine. This paper outlines the development of vector and

Mark D. Guzzi; David A. Padua; Jay Hoeflinger; Duncan H. Lawrie

1990-01-01

347

Macro motion vector quantization  

NASA Astrophysics Data System (ADS)

A new algorithm is developed for reducing the bit rate required for motion vectors. This algorithm is a generalization of block matching motion estimation in which the search region is represented as a codebook of motion vectors. The new algorithm, called macro motion vector quantization (MMVQ), generalized our earlier MVQ by coding a group of motion vectors. The codebook is a set of macro motion vectors which represent the block locations of the small neighboring blocks in the previous frame. We develop an interative design algorithm for the codebook. Our experiments show that the variances of displaced frame differences (DFDs) are reduced significantly compared to block matching algorithm (BMA) with the macroblock size.

Lee, Yoon Y.; Woods, John W.

1995-04-01

348

Change vector analysis to categorise land cover change processes using the tasselled cap as biophysical indicator: description: implementing Landsat TM and ETM to detect land cover and land use changes in the mount Cameroon region using the CVA technique with the tasselled cap as biophysical indicator.  

PubMed

The continuous extraction of wood and the conversion of forest to small- and large-scale agricultural parcels is rapidly changing the land cover of the mount Cameroon region. The changes occur at varying spatial scales most often not more than 2ha for the small-scale subsistence farms and above 10ha for the extensive agricultural plantations of cocoa and palm. Given the importance of land use and land cover data in conservation planning, accurate and efficient techniques to provide up-to-date change information are required. A number of techniques for realising the detection of land cover dynamics using remotely sensed imagery have been formulated, tested and assessed with the results varying with respect to the change scenario under investigation, the information required and the imagery applied. In this study the Change Vector Analysis (CVA) technique was implemented on multitemporal multispectral Landsat data from the Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM) sensors to monitor the dynamics of forest change in the mount Cameroon region. CVA was applied to multi-temporal data to compare the differences in the time-trajectory of the tasseled cap greenness and brightness for two successive time periods - 1987 and 2002. The tasseled cap was selected as biophysical indicator because it optimises the data viewing capabilities of vegetation, representing the basic types of land cover - vegetation, soil and water. Classes were created arbitrarily to predict the technique's potential in monitoring forest cover changes in the mount Cameroon region. The efficiency of the technique could not be fully assessed due to the inavailability of sufficient ground truth data. Assessment was based on the establishment of an error matrix of change versus no-change. The overall accuracy was 70%. The technique nevertheless demonstrated immense potentials in monitoring forest cover change dynamics especially when complemented with field studies. PMID:18193332

Siwe, Rene Ngamabou; Koch, Barbara

2008-01-12

349

Wind Farms and Weather Modification.  

NASA Astrophysics Data System (ADS)

Electrical generation by wind turbines is increasing rapidly, and has been projected to satisfy 15 percent of world electric demand by 2030. The extensive installation of wind farms would alter surface roughness and significantly impact the atmospheric circulation. This forcing could be changed deliberately by adjusting the attitude of the turbine blades with respect to the wind. Using the NCAR Community Atmosphere Model, we model the impact of time-dependent surface roughness changes due to manipulation of a continent-scale wind farm. We show that initial disturbances caused by a step change in roughness grow within four days such that the flow is altered at synoptic scales. The growth rate of the induced perturbations is largest in regions of high atmospheric instability. For a roughness change imposed over North America, the induced perturbations involve substantial changes in the track and development of cyclones over the North Atlantic. For example, in some cases, weather over the British Isles changes from cloudy to clear, depending on whether wind turbines in the American Midwest are "on" or "off" three days beforehand. We explore the dependence of the downstream effects on the size and roughness of the wind farm installation, showing that as the size of individual wind farms and turbines grows, the scale of atmospheric impacts increases in extent and magnitude. We also look at the dependence of the wind farm impacts on the initial state of the atmosphere, confirming that the impacts are largest when the wind farm perturbation projects onto growing error modes in the atmosphere. In particular, rapid growth occurs when the initial disturbance is carried into regions of high baroclinic instability such as the North Atlantic. By running ensemble experiments, we estimate the robustness of the wind farm impacts with respect to realistic uncertainty in the initial conditions. Our results suggest the possibility of a method for weather modification that in some cases could provide added value to very large wind farms.

Barrie, D. B.; Kirk-Davidoff, D. B.

2008-12-01

350

Simulating spread of Bluetongue Virus by flying vectors between hosts on pasture  

PubMed Central

Bluetongue is a disease of ruminants which reached Denmark in 2007. We present a process-based stochastic simulation model of vector-borne diseases, where host animals are not confined to a central geographic farm coordinate, but can be distributed onto pasture areas. Furthermore vectors fly freely and display search behavior to locate areas with hosts. We also include wind spread of vectors, host movements, and vector seasonality. Results show that temperature and seasonality of vectors determines the period in which an incursion of Bluetongue may lead to epidemic spread in Denmark. Within this period of risk the number of infected hosts is affected by temperature, vector abundance, vector behavior, vectors' ability to locate hosts, and use of pasture. These results indicate that restricted grazing during outbreaks can reduce the number of infected hosts and the size of the affected area. The model can be implemented on other vector-borne diseases of grazing animals.

Graesb?ll, Kaare; B?dker, Rene; En?e, Claes; Christiansen, Lasse E.

2012-01-01

351

The gustiness hypothesis: Exploring wind gusts as the primary cause of glacial-interglacial dust flux changes  

Microsoft Academic Search

During glacial periods of the Late Quaternary, mineral dust emissions from Earth's dominant source areas were approximately a factor of two higher than interglacial levels. Long-term records from the equator to the poles demonstrate that glacial-interglacial dust flux variations closely track changes in global temperature and ice volume, maintain consistent amplitudes across glacial cycles and show strong coherence between high

D. McGee; W. S. Broecker; G. Winckler

2009-01-01

352

Effects of SST-Induced Surface Wind Speed and Direction Gradients on Midlatitude Surface Vorticity and Divergence.  

National Technical Information Service (NTIS)

The effects of surface wind speed and direction gradients on midlatitude surface vorticity and divergence fields associated with mesoscale sea surface temperature (SST) variability having spatial scales of 100. 1000 km are investigated using vector wind o...

D. B. Chelton L. W. O'Neill S. K. Esbensen

2010-01-01

353

Increases in air temperature can promote wind-driven dispersal and spread of plants  

PubMed Central

Long-distance dispersal (LDD) of seeds and pollen shapes the spatial dynamics of plant genotypes, populations and communities. Quantifying LDD is thus important for predicting the future dynamics of plants exposed to environmental changes. However, environmental changes can also alter the behaviour of LDD vectors: for instance, increasing air temperature may enhance atmospheric instability, thereby altering the turbulent airflow that transports seed and pollen. Here, we investigate temperature effects on wind dispersal in a boreal forest using a 10-year time series of micrometeorological measurements and a Lagrangian stochastic model for particle transport. For a wide range of dispersal and life history types, we found positive relations between air temperature and LDD. This translates into a largely consistent positive effect of +3°C warming on predicted LDD frequencies and spread rates of plants. Relative increases in LDD frequency tend to be higher for heavy-seeded plants, whereas absolute increases in LDD and spread rates are higher for light-seeded plants for which wind is often an important dispersal vector. While these predicted increases are not sufficient to compensate forecasted range losses and environmental changes can alter plant spread in various ways, our results generally suggest that warming can promote wind-driven movements of plant genotypes and populations in boreal forests.

Kuparinen, Anna; Katul, Gabriel; Nathan, Ran; Schurr, Frank M.

2009-01-01

354

Index Sets and Vectorization  

SciTech Connect

Vectorization is data parallelism (SIMD, SIMT, etc.) - extension of ISA enabling the same instruction to be performed on multiple data items simultaeously. Many/most CPUs support vectorization in some form. Vectorization is difficult to enable, but can yield large efficiency gains. Extra programmer effort is required because: (1) not all algorithms can be vectorized (regular algorithm structure and fine-grain parallelism must be used); (2) most CPUs have data alignment restrictions for load/store operations (obey or risk incorrect code); (3) special directives are often needed to enable vectorization; and (4) vector instructions are architecture-specific. Vectorization is the best way to optimize for power and performance due to reduced clock cycles. When data is organized properly, a vector load instruction (i.e. movaps) can replace 'normal' load instructions (i.e. movsd). Vector operations can potentially have a smaller footprint in the instruction cache when fewer instructions need to be executed. Hybrid index sets insulate users from architecture specific details. We have applied hybrid index sets to achieve optimal vectorization. We can extend this concept to handle other programming models.

Keasler, J A

2012-03-27

355

Correlation between scintillation of laser beam and wind noise  

Microsoft Academic Search

The wind noise fluctuates randomly owing to the temporal changes of wind speed. The scintillation of laser beam results from temporal and spatial changes in atmospheric turbulence and\\/or pressure. In this paper, the power spectral density function (PSDF) as statistical characteristics for the wind noise is first discussed by applying the theoretical PSDF of atmospheric turbulence to this wind noise.

Y. Mitani; N. Kagawa; K. Tsutsumoto; Y. Takakuwa

2002-01-01

356

Past and future wind climates over the contiguous USA based on the North American Regional Climate Change Assessment Program model suite  

NASA Astrophysics Data System (ADS)

Multiple descriptors of wind climates over the contiguous USA from a suite of thirteen simulations conducted with five Regional Climate Models (RCMs) nested within reanalysis data and four Global Climate Models are evaluated relative to the North American Regional Reanalysis (NARR) and independent observations. Application of the RCMs improves `forecasts' of wind climates during 1979-2000 relative to the driving reanalysis, and the RCMs exhibit some skill in depicting historical wind regimes. However, the relative paucity of reference data sets for wind climates represents a significant challenge to evaluation of the modeled wind climates. Simulation of intense and extreme wind speeds by the RCMs are, to some degree, independent of the lateral boundary conditions, and instead exhibit greater dependence on the RCM architecture. RCMs that do not employ a hydrostatic formulation have higher skill in manifesting the macro-scale variability of extreme (20 and 50 year return period) wind speeds even when the RCM are applied at the spatial resolution of 50 km. Output from RCM simulations conducted for the middle of the current century (2041-2062) indicate some evidence of lower intense wind speeds particularly in the western U.S., but no difference in extreme wind speeds, relative to 1979-2000.

Pryor, S. C.; Barthelmie, R. J.; Schoof, J. T.

2012-10-01

357

On hurricane parametric wind and applications in storm surge modeling  

NASA Astrophysics Data System (ADS)

This study revisits the parametric modeling of the hurricane surface wind field composed of the storm vortex and the environmental background flow. First, we investigate the parametric representation of the surface background wind by analyzing its empirical relationship with storm movement. A marked deceleration and counter-clockwise rotation of the surface background wind from the storm translation vector is detected, a result predicted by the Ekman theory but rarely applied in wind and surge modeling. Then, we examine the various parameters used to model the wind field and, through numerical simulations, quantify their induced uncertainties in the extreme wind and surge estimates at two coastal sites. Our analyses show that, over the range of accepted values and methods in the literature, the local wind and surge estimates are most sensitive to uncertainties in the surface wind reduction factor and storm wind profile but less sensitive to uncertainties in other wind parameters, such as inflow angle and surface background wind (varying in the observed range). The surge is more sensitive than the wind to uncertainties in the wind parameters, and these sensitivities are comparable to the sensitivity of the surge to the uncertainty in the sea surface drag coefficient. We also find that some commonly used wind parameters unsupported by theory or observations can induce significant errors in the wind and surge estimates. The results of this study provide new insights and references for future hurricane wind and surge analysis.

Lin, Ning; Chavas, Daniel

2012-05-01

358

Wind Dynamics and Forests  

NSDL National Science Digital Library

In this activity, students will set up a model forest using plastic bottles to observe changes caused by differences in wind speed and forest density. An extension to the activity will allow students to explore the concept of evapotranspiration. From this activity students will understand that living organisms in an ecosystem can have profound effects upon the local atmosphere, changes in vegetation can have profound effects upon wind speed, and models are useful to researchers in understanding the shaping of ecosystems. The teacher's guide contains detailed background material, learning goals, alignment to national standards, grade level/time, details on materials and preparation, procedure, assessment ideas, and modifications for alternative learners.

359

Calibration\\/validation of the SeaWinds radiometer rain rate algorithm  

Microsoft Academic Search

The SeaWinds scatterometer, which has been flown on both the QuikSCAT and ADEOS-II satellites was designed to remotely sense ocean surface wind vectors. Because ocean wind retrievals are occasionally contaminated by rain in the tropics and because there is no independent rain measurement on QuikSCAT, a SeaWinds rain-estimation method was developed and implemented. This technique utilizes the SeaWinds receiver noise

Pet Laupattarakasem; W. Linwood Jones; Khalil Ahmad; Svetla Veleva

2005-01-01

360

Unsafe at Any (Wind) Speed?.  

NASA Astrophysics Data System (ADS)

The goal of this research was to examine the relative safety and stability of stationary motor vehicles exposed to severe winds. The focus was on private passenger vehicles. 1) The behavior of two instrumented storm-chase vehicles that were exposed to severe winds, 2) the behavior of 291 vehicles exposed to a tornado, and 3) the wind speed required to upset a sedan and a minivan exposed to winds in a wind tunnel were studied. A wind as strong as 47 m s1 (105 mph) has been measured by a storm-chase pickup truck and 44 m s1 (98 mph) by a storm chase sedan. The vehicles were not adversely affected by the wind. Also studied were 291 vehicles parked outdoors at homes struck by tornadoes, and the behavior of the vehicles was compared to the F-scale damage to the house. At sites with F1 or F2 damage, 72% of the vehicles were not moved by the wind and 96% were not tipped over. At sites with F3 or F4 damage, 50% were not moved by the wind and 82% were not tipped over. Wind tunnel tests on a sedan and minivan showed they were most vulnerable to upset (lifting of one tire from the ground) with wind directions near 45° and 135°, as measured from the front. When modeled with 5° of suspension tilt to the side, the sedan was found to be upset at wind speeds of 51-67 m s1 (115-150 mph), and the minivan was upset at wind speeds of 58-80 m s1 (130-180 mph). Although an underground shelter or sturdy building offer the best protection from severe winds, it is found that a vehicle may be a relatively stable place and may be safer than a mobile home or the outdoors. These findings may warrant changes to public recommendations made during tornado warnings and other severe storm situations.

Schmidlin, Thomas; Hammer, Barbara; King, Paul; Ono, Yuichi; Miller, L. Scott; Thumann, Gregory

2002-12-01

361

Society for Vector Ecology  

NSDL National Science Digital Library

Formed in 1968, the Society for Vector Ecology (SOVE) is dedicated to studying "all aspects of the biology, ecology, and control of arthropod vectors and the interrelationships between the vectors and the disease agents they transmit." Comprised of researchers and operational and extension personnel around the globe, SOVE tracks and studies the biological organisms that transmit diseases. The SOVE Website contains information related to the Society (e.g., mission, history), its publications (journal, newsletter -- both .pdf format), and professional opportunities (conferences, employment). Several dozen links to additional vector ecology resources are provided.

2002-01-01

362

Population genetic structure of the malaria vector Anopheles funestus, in a recently re-colonized area of the Senegal River basin and human-induced environmental changes  

PubMed Central

Background Anopheles funestus is one of the major malaria vectors in tropical Africa. Because of several cycles of drought events that occurred during the 1970s, this species had disappeared from many parts of sahelian Africa, including the Senegal River basin. However, this zone has been re-colonized during the last decade by An. funestus, following the implementation of two dams on the Senegal River. Previous studies in that area revealed heterogeneity at the biological and chromosomal level among these recent populations. Methods Here, we studied the genetic structure of the newly established mosquito populations using eleven microsatellite markers in four villages of the Senegal River basin and compared it to another An. funestus population located in the sudanian domain. Results Our results presume Hardy Weinberg equilibrium in each An. funestus population, suggesting a situation of panmixia. Moreover, no signal from bottleneck or population expansion was detected across populations. The tests of genetic differentiation between sites revealed a slight but significant division into three distinct genetic entities. Genetic distance between populations from the Senegal River basin and sudanian domain was correlated to geographical distance. In contrast, sub-division into the Senegal River basin was not correlated to geographic distance, rather to local adaptation. Conclusions The high genetic diversity among populations from Senegal River basin coupled with no evidence of bottleneck and with a gene flow with southern population suggests that the re-colonization was likely carried out by a massive and repeated stepping-stone dispersion starting from the neighboring areas where An. funestus endured.

2012-01-01

363

Late 20th century atmospheric circulation changes: Implications for tropical tropospheric warming based on thermal winds and the role of absorbing aerosols  

Microsoft Academic Search

Climate models and theoretical expectations have predicted that the upper troposphere should be warming faster than the surface. Direct temperature observations from radiosonde and satellite data have often not shown this expected trend; but non-climatic biases have been found in such measurements. An alternative approach is used to infer tropospheric temperature trends from wind measurements, using the thermal wind equation

Robert J. Allen

2009-01-01

364

Wind energy  

Microsoft Academic Search

General resources of wind energy are evaluated, and its main applications are considered, such as conversion into electricity and heat, hydrogen production, and irrigation, along with the associated problem of long-term energy storage. The basic principles of windmill system design and favorable location selection are outlined. The environmental impact of the windmill systems is discussed. It is noted that wind

B. Sorensen

1976-01-01

365

Examining the Variability of Wind Power Output in the Regulation Time Frame: Preprint  

SciTech Connect

This work examines the distribution of changes in wind power for different time scales in the regulation time frame as well as the correlation of changes in power output for individual wind turbines in a wind plant.

Hodge, B. M.; Shedd, S.; Florita, A.

2012-08-01

366

Developing Wind Energy in the European Union  

Microsoft Academic Search

Wind energy is the fastest-growing electricity-generating technology. The wind energy targets set during the last decade have all been surpassed. New targets are proposed for 2010 and 2020, since the existing European Commission and European Wind Energy Association targets do not reflect the trends in the market. Climate change is a major challenge to sustainable development worldwide and is increasingly

Kamil Kaygusuz

2006-01-01

367

Radial Evolution of Solar Wind Speeds (Postprint).  

National Technical Information Service (NTIS)

The WSA ENLIL model predicts significant evolution of the solar wind speed. Along a flux tube the solar wind speed at 1.0 AU and beyond is found to be significantly altered from the solar wind speed in the outer corona at 0.1 AU, with most of the change o...

C. N. Arge D. Odstreil N. A. Schwadron S. L. McGregor W. J. Hughes

2012-01-01

368

ARCTIC TROPOSPHERIC WINDS FROM SATELLITE SOUNDERS  

Microsoft Academic Search

Accurate three-dimensional wind fields are essential for diagnosing a variety of important climate pro- cesses in the Arctic, such as the advection and deposition of heat and moisture, changes in circulation fea- tures, and transport of trace constituents. In light of recent studies revealing significant biases in upper-level winds over the Arctic Ocean from reanalyses, we generate new daily wind

J. A. Francis; E. Hunter; Z. Zou

369

Changes in phytoplankton composition in response to tides, wind-induced mixing conditions, and freshwater outflows in an urbanised estuarine complex.  

PubMed

Recent reports have shown an increase in potentially harmful phytoplankton in Santos bay (Southeastern Brazilian Coast), located in a highly urbanised estuarine complex. Prediction of blooms is, thus, essential but the phytoplankton community structure in very dynamic regions is difficult to determine. In the present work, we discriminate bloom forming microphytoplankton dominance and their relationship to physical and meteorological variables to look for patterns observed in different tides and seasons. Comparing 8 distinct situations, we found five scenarios of dominance that could be related to winds, tides and rainfall: i) Surfers, diatoms occurring during high surf zone energies; ii) Sinkers, represented by larger celled diatoms during spring tide, after periods of high precipitation rates; iii) Opportunistic mixers, composed of chain forming diatoms with small or elongate cells occurring during neap tides; iv) Local mixers, microplanktonic diatoms and dinoflagellates which occurred throughout the 298 sampling stations; and v) Mixotrophic dinoflagellates, after intense estuarine discharges. Results suggest alterations in the temporal patterns for some bloom-forming species, while others appeared in abundances above safe limits for public health. This approach can also illustrate possible impacts of changes in freshwater discharge in highly urbanised estuaries. PMID:22437390

Moser, G A O; Ciotti, A M; Giannini, M F C; Tonini, R T; Harari, J

2012-02-01

370

Equivalent wind speed model of wind generation  

Microsoft Academic Search

The time series intervals of wind speed and wind power prediction are from a few minutes to ten minutes, which are used for power system energy dispatch, and the power is a mean value in the interval. But physical parameters for wind, such as instantaneous wind speed, maximum wind speed, average wind speed, cannot describe the relationship properly between the

Jing Tian-jun; Yang Ming-hao

2010-01-01

371

Understanding Inertial and Frequency Response of Wind Power Plants: Preprint  

SciTech Connect

The objective of this paper is to analyze and quantify the inertia and frequency responses of wind power plants with different wind turbine technologies (particularly those of fixed speed, variable slip with rotor-resistance controls, and variable speed with vector controls).

Muljadi, E.; Gevorgian, V.; Singh, M.; Santoso, S.

2012-07-01

372

Polarimetric vector diffraction tomography  

Microsoft Academic Search

Scalar linearized inverse scattering has recently found a unified treatment within the framework of diffraction tomography in either frequency or angular diversity. The linear inverse scattering theory can be extended to electromagnetic vector fields to include complete polarization information. Its essential feature is the formulation of a vector Porter-Bojarski integral equation to be inverted by dyadic algebra. Algorithms are discussed

Michael Brandfass; K. J. Langenberg; A. Fritsch

1994-01-01

373

Retroviruses as vectors.  

PubMed

Recombinant retroviruses have long been used to deliver heterologous genes to mammalian cells. Convenient packaging cell lines and vector plasmids have been distributed widely and 'home-made' retroviral vectors have now become a useful research tool in many laboratories. Compared to more traditional methods of gene transfer, retroviral vectors are extraordinarily efficient gene delivery vehicles which cause no detectable harm as they enter their target cells. In the nucleus the retroviral necleic acid becomes integrated into chromosomal DNA, ensuring its long-term persistence and stable transmission to all future progeny of the transduced cell. Up to 8 kilobases of foreign gene sequence can be packaged in a retroviral vector and this is more than enough for most gene therapy applications. Retroviral vectors can also be manufactured in large quantities to meet very stringent safety specifications. They have therefore been selected as the vectors of choice in 80% of the clinical gene therapy trials that have been approved to date. So far there have been no reported short- or long-term toxicity problems associated with their use in human gene therapy trials, now dating back to 1989. However, despite this impressive record, there is still great scope (and need) for the development of new, improved retroviral vectors and packaging systems to fuel further advances in the field of human gene therapy. In the following discussion, existing retroviral vectors are reviewed and current areas of technological development are emphasised. PMID:7767638

Vile, R G; Russell, S J

1995-01-01

374

New Support Vector Algorithms  

Microsoft Academic Search

We propose a new class of support vector algorithms for regression and classification. In these algorithms, a parameter ? lets one effectively control the number of support vectors. While this can be useful in its own right, the parameterization has the additional benefit of enabling us to eliminate one of the other free parameters of the algorithm: the accuracy parameter

Bernhard Schölkopf; Alex J. Smola; Robert C. Williamson; Peter L. Bartlett

2000-01-01

375

Exploring acceleration through vectors  

NSDL National Science Digital Library

This in class worksheet is designed to get students to think about and manipulate different accelerations in their head. Students work together with written descriptions of velocity and acceleration and draw the vectors in part one, and then turn that around in part two where they write descriptions of a car's motion based on the vector pictures they are given.

376

Insect vector transmission assays.  

PubMed

Phytoplasmas are transmitted in a persistent propagative manner by phloem-feeding vectors belonging to the order Hemiptera, suborder Homoptera. Following acquisition from the infected source plant, there is a latent period before the vector can transmit, so transmission assays consist of three basic steps: acquisition, latency, and inoculation. More than 90 vector species (plant-, leafhoppers, and psyllids) have been discovered so far but many others are still undiscovered, and their role in spreading economically important crop diseases is neglected. Therefore, screening for vectors is an essential step in developing rational control strategies targeted against the actual vectors for phytoplasma-associated diseases. The mere detection of a phytoplasma in an insect does not imply that the insect is a vector; a transmission assay is required to provide conclusive evidence. Transmission experiments can be carried out using insects from phytoplasma-free laboratory colonies or field-collections. Moreover, transmission assays can be performed by feeding vectors on an artificial diet through Parafilm(®), after which phytoplasmas can be detected in the sucrose feeding medium by PCR. Transmission trials involve the use of different techniques according to the biology of the different vector species; planthoppers, leafhoppers, and psyllids. PMID:22987407

Bosco, Domenico; Tedeschi, Rosemarie

2013-01-01

377

MODELUNG OF PAN EVAPORATION USING SUPPORT VECTOR MACHINES ALGORITHM  

Microsoft Academic Search

This paper present results of pan evaporation estimations using Support Vector Machines (SVMs) based approach for the meteorological data from Manasgaon climatic station near Anand Sagar Reservoir, Shegaon. At this station four meteorological variables are measured simultaneously, namely, air temperature, wind speed, sunshine hours and relative humidity. The SVMs architecture involves in using one output parameter (i.e. evaporation) and up

S. Deswal; Mahesh Pal

2008-01-01

378

Multiterminal LVDC system for optimal acquisition of power in wind-farm using induction generators  

Microsoft Academic Search

Optimal wind-power acquisition requires automatic tracking of the optimum wind-turbine speed for the prevailing wind velocity. As the wind velocity keeps changing with time so the wind-turbine must keep adjusting its speed. In a wind-farm, the wind velocities depend on the locations of the wind-turbines, each of which has its optimal turbine speed at any given time. With an eye

Weixing Lu; Boon Teck Ooi

2002-01-01

379

Study and simulation of space vector PWM control of double-star induction motors  

Microsoft Academic Search

This paper deals with a comparison between different structures of double-star induction motors (DSIMs), controlled by space vector PWM. The modelling of the DSIM is made using an arbitrary shift angle between the two three-phase windings. A new transformation matrix is proposed to develop a suitable dynamic model and to elaborate the space vector PWM control strategy for different values

D. Hadiouche; H. Razik; A. Rezzoug

2000-01-01

380

Intracellular trafficking of nonviral vectors  

Microsoft Academic Search

Nonviral vectors continue to be attractive alternatives to viruses due to their low toxicity and immunogenicity, lack of pathogenicity, and ease of pharmacologic production. However, nonviral vectors also continue to suffer from relatively low levels of gene transfer compared to viruses, thus the drive to improve these vectors continues. Many studies on vector–cell interactions have reported that nonviral vectors bind

L K Medina-Kauwe; J Xie; S Hamm-Alvarez

2005-01-01

381

Investigation of winds in Venus mesosphere by digital method using UV images from VMC aboard Venus Express.  

NASA Astrophysics Data System (ADS)

Investigation of winds at the top cloud layer is important for understanding the global circulation of the Venus atmosphere. The Venus Monitoring Camera (VMC) aboard Venus Express has acquired a huge number of UV (365 nm) images. UV images of top cloud layer are customary to obtain the wind velocity due to their high contrast. Visual estimation of wind velocities is a labor intensive procedure. Authors have developed a digital method to estimate velocities of shifts of cloud details. The method is based on analysis of correlations between two UV images acquired at different moments. The method takes into account the change of a correlation function due to latitudinal peculiarities of cloud morphology and eliminates image regions which are far from the sub-spacecraft point. The digital method provides with good vector coverage of the Venus day side (9-16 local time) from the equator to high latitudes. The best agreement between the digital and visual methods is observed at low latitudes (below 35S). The discrepancy at higher latitudes is related to complicated cloud morphology, namely domination of streaks, which increases errors in the zonal wind speed. The method is productive for long-scale circulation at the top cloud layer. Sizes of regions for correlation were chosen empirically as a trade-off of sensitivity against noise immunity and varies from 10x7.5 ° to 20x10 ° depending on grid step. 580 orbits covering ten Venus years have been processed by using the digital method. The database of shift vectors counts about 400000 records. The mean wind speed at low latitudes is about 100 m/s. Wind vector fields were obtained for every orbit. The zonal wind speed in the equatorial region exhibits short-period (about 4.8 days) and long-period variations (long-term trend). Vector field averaged by all orbits show deviations of the main stream up to 5 degrees poleward in the early afternoon (12.5-14.5h) at 45-55S. The mean absolute value of the wind speed increases from 59.38 m/s at 10-12h to 76.46 m/s at 12.5-14.5h at the same latitude interval.

Patsaeva, Marina; Khatuntsev, Igor; Ignatiev, Nikolai

2013-04-01

382

Vector theories in cosmology  

SciTech Connect

This article provides a general study of the Hamiltonian stability and the hyperbolicity of vector field models involving both a general function of the Faraday tensor and its dual, f(F{sup 2},FF-tilde), as well as a Proca potential for the vector field, V(A{sup 2}). In particular it is demonstrated that theories involving only f(F{sup 2}) do not satisfy the hyperbolicity conditions. It is then shown that in this class of models, the cosmological dynamics always dilutes the vector field. In the case of a nonminimal coupling to gravity, it is established that theories involving Rf(A{sup 2}) or Rf(F{sup 2}) are generically pathologic. To finish, we exhibit a model where the vector field is not diluted during the cosmological evolution, because of a nonminimal vector field-curvature coupling which maintains second-order field equations. The relevance of such models for cosmology is discussed.

Esposito-Farese, Gilles; Pitrou, Cyril; Uzan, Jean-Philippe [GRECO, Institut d'Astrophysique de Paris, UMR 7095-CNRS, Universite Pierre et Marie Curie-Paris 6, 98bis boulevard Arago, F-75014 Paris (France); Institute of Cosmology and Gravitation, Dennis Sciama Building, Burnaby Road, Portsmouth, PO1 3FX (United Kingdom); GRECO, Institut d'Astrophysique de Paris, UMR 7095-CNRS, Universite Pierre et Marie Curie-Paris 6, 98bis boulevard Arago, F-75014 Paris (France) and Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch 7701, Cape Town (South Africa)

2010-03-15

383

Vector generator scan converter  

DOEpatents

High printing speeds for graphics data are achieved with a laser printer by transmitting compressed graphics data from a main processor over an I/O channel to a vector generator scan converter which reconstructs a full graphics image for input to the laser printer through a raster data input port. The vector generator scan converter includes a microprocessor with associated microcode memory containing a microcode instruction set, a working memory for storing compressed data, vector generator hardware for drawing a full graphic image from vector parameters calculated by the microprocessor, image buffer memory for storing the reconstructed graphics image and an output scanner for reading the graphics image data and inputting the data to the printer. The vector generator scan converter eliminates the bottleneck created by the I/O channel for transmitting graphics data from the main processor to the laser printer, and increases printer speed up to thirty fold. 7 figs.

Moore, J.M.; Leighton, J.F.

1988-02-05

384

Assessment of the ASCAT wind error characteristics by global dropwindsonde observations  

NASA Astrophysics Data System (ADS)

This research focuses on assessing the accuracy of the advanced scatterometer (ASCAT) wind vector around tropical cyclones by using data from dropwindsondes deployed by the surveillance and reconnaissance flights during 2007-2010. There are 987 matching samples for the comparisons, with wind speed up to 50 m s-1. The bias and root-mean-square differences of wind speed between ASCAT and dropwindsonde data are -1.7 and 5.3 m s-1, respectively. Further analyses also indicate that large wind direction differences occur in the low wind speed regime, while large wind speed differences occur in the high wind speed regime. The accuracy of wind vector in weak wind speed and high wind speed regimes are significantly reduced in saturated regions, implying that the rain contamination issue still affects the accuracy of ASCAT wind retrieval. The wind vector in the medium wind speed regime has much better quality, in good agreement with the satellite's designed specification. The ASCAT wind data obviously contain negative wind speed bias, which grows larger as wind speed increases. A regression fit between ASCAT and dropwindsonde wind speed is adopted to correct the bias of the ASCAT wind speed. The error characteristics are largely determined by the magnitude of wind speed and moisture saturation which are highly variable around the storm. Nevertheless, results from this study suggest that ASCAT wind data of velocities measuring between 12 and 18 m s-1 are more reliable and can be applied to determine the radius of 34 knot winds, a critical parameter in operational tropical cyclone analysis.

Chou, Kun-Hsuan; Wu, Chun-Chieh; Lin, Shu-Zheng

2013-08-01

385

Aquarius Scatterometer Winds  

NASA Astrophysics Data System (ADS)

Aquarius is a combined passive/active L-band microwave instrument developed to map the salinity field at the surface of the ocean from space. The data will support studies of the coupling between ocean circulation, the global water cycle, and climate. The primary science objective of this mission is to monitor the seasonal and interannual variation of the large scale features of the surface salinity field in the open ocean with a spatial resolution of 150 km and a retrieval accuracy of 0.2 psu globally on a monthly basis. The measurement principle is based on the response of the L-band (1.413 GHz) sea surface brightness temperatures to sea surface salinity. To achieve the required 0.2 psu accuracy, the impact of sea surface roughness (e.g. wind-generated ripples and waves), along with several additional factors impacting the observed brightness temperature, must be corrected to better than a few tenths of a degree Kelvin. To this end, Aquarius includes a scatterometer to help correct for this surface roughness effect. The Aquarius/SACD was launched successfully on June 10, 2011, and the instrument is expected to be turned on in August. The prelaunch tests of Aquarius showed that the instrument should be extremely stable at the week-to-month time scale with drift of less than 0.1 K for the radiometer and 0.1 dB for the scatterometer. The current baseline algorithm for Aquarius is to use the scatterometer data in conjunction with the NCEP wind direction to derive the ocean surface wind speed and then a radiometer roughness correction. The pre-launch simulations predict 1 m/s wind speed accuracy. This will be tested using the Aquarius data collected in the coming few months. To quantify the benefits of combining passive and active microwave sensors for ocean salinity remote sensing, the Passive/Active L-band Sensor (PALS) was used to acquire data over a wide range of ocean surface wind conditions during the High Ocean Wind (HOW) Campaign in 2009. The PALS brightness temperatures and the radar ?0 from the campaign show response to ocean surface wind speed as well as direction. The brightness temperature changes are about 0.2 to 0.3 K for every one m/s change in wind speed. In addition, there is significant wind direction dependence for high winds (>10 m/s), about 0.5 K peak to peak at 9 m/s wind speed and 1.5 K at 24 m/s wind speed. Using the PALS data, we have tested the ability to use the combined active and passive microwave to retrieve the wind speed and direction. The accuracy of retrievals is estimated to be about 1 m/s in wind speed and 15 degrees in direction. Using the Aquarius data, we will update the geophysical model functions for scatterometer and radiometer, which will then be applied for the retuning of wind retrieval algorithms. The retrieval analyses using PALS data and preliminary calibrated Aquarius data will be presented.

Yueh, S. H.; Fore, A.; Freedman, A. P.; Neumann, G.; Tang, W.; Brown, S.; Chaubell, M. J.; Jones, L.; Lagerloef, G. S.; LeVine, D.; Dinnat, E. P.; Meissner, T.; Wentz, F. J.; Vandemark, D. C.

2011-12-01

386

Offshore wind energy prospects  

Microsoft Academic Search

In last two years offshore wind energy is becoming a focal point of national and non national organizations particularly after the limitations of fossil fuel consumption, adopted by many developed countries after Kyoto conference at the end of 1997 on global climate change. North Europe is particularly interested in offshore for the limited land areas still available, due to the

Gaetano Gaudiosi

1999-01-01

387

Winds influence Bering Shelf circulation  

NASA Astrophysics Data System (ADS)

Circulation over the Bering Sea shelf and between the shelf and the adjacent deep basin affects the ecosystem through nutrient exchange, egg and larvae dispersal, and changes in temperature and salinity. Using numerical models and observations, Danielson et al. present a new simple framework showing how circulation on the Bering shelf varies with wind forcing. They f n d two primary modes of wind forcing, and changes in wind direction tend to reverse the flow around the shelf. Northwesterly winds, which are more common, promote off-shelf transport along the majority of the continental slope, while southeasterly winds, which are less frequent, are associated with greater on-shelf transport. The study improves overall understanding of the Bering shelf circulation. (Geophysical Research Letters, doi:10.1029/2012GL051231, 2012)

Balcerak, Ernie

2012-05-01

388

Viral Vector Induction of CREB Expression in the Periaqueductal Gray Induces a Predator Stress-Like Pattern of Changes in pCREB Expression, Neuroplasticity, and Anxiety in Rodents  

PubMed Central

Predator stress is lastingly anxiogenic. Phosphorylation of CREB to pCREB (phosphorylated cyclic AMP response element binding protein) is increased after predator stress in fear circuitry, including in the right lateral column of the PAG (periaqueductal gray). Predator stress also potentiates right but not left CeA-PAG (central amygdala-PAG) transmission up to 12 days after stress. The present study explored the functional significance of pCREB changes by increasing CREB expression in non-predator stressed rats through viral vectoring, and assessing the behavioral, electrophysiological and pCREB expression changes in comparison with handled and predator stressed controls. Increasing CREB expression in right PAG was anxiogenic in the elevated plus maze, had no effect on risk assessment, and increased acoustic startle response while delaying startle habituation. Potentiation of the right but not left CeA-PAG pathway was also observed. pCREB expression was slightly elevated in the right lateral column of the PAG, while the dorsal and ventral columns were not affected. The findings of this study suggest that by increasing CREB and pCREB in the right lateral PAG, it is possible to produce rats that exhibit behavioral, brain, and molecular changes that closely resemble those seen in predator stressed rats.

Adamec, Robert; Berton, Olivier; Abdul Razek, Waleed

2009-01-01

389

Assessing the performance of Intergovernmental Panel on Climate Change AR5 climate models in simulating and projecting wind speeds over China  

NASA Astrophysics Data System (ADS)

The ability of nine current generation (Coupled Model Intercomparison Project Phase 5, CMIP-5) coupled atmosphere-ocean general circulation models (AOGCMs) to accurately simulate the near-surface wind climate over China is evaluated by comparing output from the historical period (1971-2005) with an observational data set and reanalysis output. Results suggest the AOGCMs show substantial positive bias in the mean 10 m wind speed relative to observations and the ERA-40, National Centers for Environmental Prediction-Department of Energy, and National Centers for Environmental Prediction-National Center for Atmospheric Research reanalysis. Given that the models generally produce the upper level geopotential height gradients comparatively well, it is postulated that one major reason for the discrepancy between observed and modeled wind fields is the surface characterization used in the AOGCMs. All models exhibit lower interannual variability than reanalysis data and observations, and none of the models reproduce the recent decline in wind speed that is manifest in the near-surface observations. The wind speed of individual model runs during the historical period does not exhibit much influence from the initial atmospheric conditions. The output for the current century from seven of the AOGCMs is examined relative to the historical wind climate. The results indicate that spatial fields of wind speed at the end of the 21st century are very similar to those of the last 35 years with comparatively little response to the precise representative concentration pathway scenario applied.

Chen, Lian; Pryor, S. C.; Li, Dongliang

2012-12-01

390

DFIG-based wind farm electromagnetic dynamic model and impact on protection relay of transmission network  

Microsoft Academic Search

A DFIG-based wind generator electromagnetic transient model is established on the RTDS platform in this paper. Stator flux oriented vector control scheme is adopted to achieve power decoupling control in the DFIG based wind model. In order to research the impact of the wind farm on the existing protection relay of the network, this paper establishes single machine electromagnetic dynamic

Guanghui Li; Baohui Zhang; Jin Wang; Zhiqian Bo; Tony Yip; David Writer; Yu-ming Lei

2011-01-01

391

Wind Chill!  

NSDL National Science Digital Library

In this activity students use a variety of windchill charts to determine how cold the temperature feels versus how cold it really is. Students experiment with cooling due to evaporation with and without wind. Students tie their knowledge of wind chill to understanding the impact of cold and wind in the polar environment and prevention of dangerous conditions. Students will graph and present their findings, predict and explore how this phenomenon impacts living in polar regions, and suggest measures that can curtail the impact.

Wygoda, Linda

392

Vectorization of a Multiprocessor Multifrontal Code  

Microsoft Academic Search

We describe design changes that enhance the vectoriza tion of a multiprocessor version of a multifrontal code for the direct solution of large sparse sets of linear equations. These changes employ techniques used with success in full Gaussian elimination and are based on the use of matrix-vector and matrix-matrix kernels as implemented in the Level 2 and Level 3 BLAS.

Patrick R. Amestoy; lain S. Duff

1989-01-01

393

Wind Surge  

NSDL National Science Digital Library

This site features an interactive applet from the University of Delaware. The applet illustrates the way water can pile up against the downwind side (of a basin) due to stresses exerted on the surface by strong wind.

Dalrymple, Robert A.; Delaware, University O.

394

Quadratic exponential vectors  

SciTech Connect

We give a necessary and sufficient condition for the existence of a quadratic exponential vector with test function in L{sup 2}(R{sup d}) intersection L{sup {infinity}}(R{sup d}). We prove the linear independence and totality, in the quadratic Fock space, of these vectors. Using a technique different from the one used by Accardi et al. [Quantum Probability and Infinite Dimensional Analysis, Vol. 25, p. 262, (2009)], we also extend, to a more general class of test functions, the explicit form of the scalar product between two such vectors.

Accardi, Luigi; Dhahri, Ameur [Volterra Center, University of Roma Tor Vergata, Via Columbia 2, 00133 Roma (Italy)

2009-12-15

395

Statistical downscaling of sea-surface wind over the Peru–Chile upwelling region: diagnosing the impact of climate change from the IPSL-CM4 model  

Microsoft Academic Search

The key aspect of the ocean circulation off Peru–Chile is the wind-driven upwelling of deep, cold, nutrient-rich waters that\\u000a promote a rich marine ecosystem. It has been suggested that global warming may be associated with an intensification of upwelling-favorable\\u000a winds. However, the lack of high-resolution long-term observations has been a limitation for a quantitative analysis of this\\u000a process. In this

K. Goubanova; V. Echevin; B. Dewitte; F. Codron; K. Takahashi; P. Terray; M. Vrac

2011-01-01

396

Wind turbine system  

SciTech Connect

A wind turbine system utilizes a bicycle wheel type turbine having airfoils mounted on various spoke pairs. The vertical yaw axis lies in the horizontal projection of the airfoils to offer better control of the system; for example, automatic stowage in the case of excessive wind is provided since the superstructure of the turbine provides a torque around the vertical yaw axis which moves the wheel into a stowed position. At the same time, the wheel diameter can be made larger and thus heavier since the drive connection to the generator also helps support the weight of the wheel, since it is a rim drive. Greater electrical generation is also provided since an air scoop facing into the wind allows the effective generator capacity to be increased with air velocity. Lastly, the radial rate of change of the angle of the airfoils can be closely controlled.

Smith, O.J.

1982-05-18

397

Household model of Chagas disease vectors (Hemiptera: Reduviidae) considering domestic, peridomestic, and sylvatic vector populations.  

PubMed

ABSTRACT Disease transmission is difficult to model because most vectors and hosts have different generation times. Chagas disease is such a situation, where insect vectors have 1-2 generations annually and mammalian hosts, including humans, can live for decades. The hemataphagous triatominae vectors (Hemiptera: Reduviidae) of the causative parasite Trypanosoma cruzi (Kinetoplastida: Trypanosomatidae) usually feed on sleeping hosts, making vector infestation of houses, peridomestic areas, and wild animal burrows a central factor in transmission. Because of difficulties with different generation times, we developed a model considering the dwelling as the unit of infection, changing the dynamics from an indirect to a direct transmission model. In some regions, vectors only infest houses; in others, they infest corrals; and in some regions, they also infest wild animal burrows. We examined the effect of sylvatic and peridomestic vector populations on household infestation rates. Both sylvatic and peridomestic vectors increase house infestation rates, sylvatic much more than peridomestic, as measured by the reproductive number R0. The efficacy of manipulating parameters in the model to control vector populations was examined. When R0 > 1, the number of infested houses increases. The presence of sylvatic vectors increases R0 by at least an order of magnitude. When there are no sylvatic vectors, spraying rate is the most influential parameter. Spraying rate is relatively unimportant when there are sylvatic vectors; in this case, community size, especially the ratio of houses to sylvatic burrows, is most important. The application of this modeling approach to other parasites and enhancements of the model are discussed. PMID:23926791

Stevens, L; Rizzo, D M; Lucero, D E; Pizarro, J C

2013-07-01

398

Observations of Electrostatic Solitary Waves as Evidence of Kinetic Instabilities and Magnetic Reconnection at Solar Wind Current Sheets  

NASA Astrophysics Data System (ADS)

Using data from the Wind spacecraft, we present observations of a strong spatial association between bipolar electrostatic solitary waves (ESW) and magnetic discontinuities (current sheets) in the solar wind. This association implies that the kinetic plasma instabilities (e.g. Buneman, electron two-stream) responsible for creating ESW are both active in the solar wind and localized to current sheets. The presence of these kinetic instabilities suggests the transfer of magnetic energy to plasma kinetic energy at solar wind current sheets either through the saturation of current-driven kinetic instabilities or through magnetic reconnection. Distributions of current sheet properties are compared between current sheets associated with ESW and randomly chosen current sheets. No significant difference is found between these two populations with respect to shear angle, thickness, plasma beta, or vector magnetic field change, implying that the generation of ESW at current she! ets occurs throughout the solar wind at 1 AU. Of the possible mechanisms considered for producing ESW-generating kinetic instabilities at solar wind current sheets, we argue that magnetic reconnection is the most consistent with observations.

Malaspina, D. M.; Newman, D. L.; Wilson, L. B., III; Goetz, K.; Kellogg, P. J.; Kersten, K.

2012-12-01

399

Understanding Vector Fields.  

ERIC Educational Resources Information Center

|Presented are activities that help students understand the idea of a vector field. Included are definitions, flow lines, tangential and normal components along curves, flux and work, field conservation, and differential equations. (KR)|

Curjel, C. R.

1990-01-01

400

Targeted adenoviral vectors  

NASA Astrophysics Data System (ADS)

The practical implementation of gene therapy in the clinical setting mandates gene delivery vehicles, or vectors, capable of efficient gene delivery selectively to the target disease cells. The utility of adenoviral vectors for gene therapy is restricted by their dependence on the native adenoviral primary cellular receptor for cell entry. Therefore, a number of strategies have been developed to allow CAR-independent infection of specific cell types, including the use of bispecific conjugates and genetic modifications to the adenoviral capsid proteins, in particular the fibre protein. These targeted adenoviral vectors have demonstrated efficient gene transfer in vitro , correlating with a therapeutic benefit in preclinical animal models. Such vectors are predicted to possess enhanced efficacy in human clinical studies, although anatomical barriers to their use must be circumvented.

Douglas, Joanne T.

401

LTR-Vectors.  

National Technical Information Service (NTIS)

The patent application describes the production of vectors composed of portions of retrovirus, particularly of Moloney sarcoma virus DNA including the 'LTR' sequence which can activate genes and additional viral sequences which can 'rescue' these genes in...

G. F. Vande Woude W. L. McClements M. K. Oskarsson D. G. Blair

1981-01-01

402

Vector Mesons at HERA  

SciTech Connect

The rich experimental landscape of exclusive vector meson production at the high energy electron-proton collider HERA is reviewed, with emphasis on the transition from soft to hard diffraction and perturbative QCD interpretations.

Favart, L

2009-03-23

403

Construction of solar-wind-like magnetic fields.  

PubMed

Fluctuations in the solar wind fields tend to not only have velocities and magnetic fields correlated in the sense consistent with Alfvén waves traveling from the Sun, but they also have the magnitude of the magnetic field remarkably constant despite their being broadband. This Letter provides, for the first time, a method for constructing fields with nearly constant magnetic field, zero divergence, and with any specified power spectrum for the fluctuations of the components of the field. Every wave vector, k, is associated with two polarizations; the relative phases of these can be chosen to minimize the variance of the field magnitude while retaining the "random" character of the fields. The method is applied to a case with one spatial coordinate that demonstrates good agreement with observed time series and power spectra of the magnetic field in the solar wind, as well as with the distribution of the angles of rapid changes ("discontinuities"), thus showing a deep connection between two seemingly unrelated issues. It is suggested that using this construction will lead to more realistic simulations of solar wind turbulence and of the propagation of energetic particles. PMID:23368180

Roberts, D Aaron

2012-12-04

404

Construction of Solar-Wind-Like Magnetic Fields  

NASA Astrophysics Data System (ADS)

Fluctuations in the solar wind fields tend to not only have velocities and magnetic fields correlated in the sense consistent with Alfvén waves traveling from the Sun, but they also have the magnitude of the magnetic field remarkably constant despite their being broadband. This Letter provides, for the first time, a method for constructing fields with nearly constant magnetic field, zero divergence, and with any specified power spectrum for the fluctuations of the components of the field. Every wave vector, k, is associated with two polarizations; the relative phases of these can be chosen to minimize the variance of the field magnitude while retaining the “random” character of the fields. The method is applied to a case with one spatial coordinate that demonstrates good agreement with observed time series and power spectra of the magnetic field in the solar wind, as well as with the distribution of the angles of rapid changes (“discontinuities”), thus showing a deep connection between two seemingly unrelated issues. It is suggested that using this construction will lead to more realistic simulations of solar wind turbulence and of the propagation of energetic particles.

Roberts, D. Aaron

2012-12-01

405

Poynting-vector filter  

SciTech Connect

A determination is made of frequency components associated with a particular bearing or location resulting from sources emitting electromagnetic-wave energy for which a Poynting-Vector can be defined. The broadband frequency components associated with a specific direction or location of interest are isolated from other components in the power spectrum that are not associated with the direction or location of interest. The collection of pointing vectors can be used to characterize the source.

Carrigan, Charles R. (Tracy, CA)

2011-08-02

406

Optics for vector scanning  

Microsoft Academic Search

Vector scanning of laser beams is critical to the success of stereolithography, laser marking, CAD-output-to-microfilm and many other industrial applications. The design of a vector scan lens system can assume many different configurations. This paper will discuss pre-objective, and post-objective alternatives for two and three axis scanning. Various parameters required for system specification are reviewed and the basic configuration of

Jonathan S. Ehrmann

1991-01-01

407

Local wind or Russian gas? Contextual influences on Polish attitudes to wind energy developments  

Microsoft Academic Search

A survey was completed by 200 residents of two localities (100 each) in Northern Poland, a target community affected by proposals for nearby wind farms, and an unaffected control community. Compared with controls, targets were, on average, less favourable towards wind energy development, both locally and elsewhere in Poland, were less convinced that wind energy would help mitigate climate change,

J Richard Eiser; Katarzyna Aluchna; Christopher R Jones

2010-01-01

408

Wind Energy Deployment Issue Brief - May 2010  

Microsoft Academic Search

Wind energy projects have been proposed all over the world. West Michigan coastal communities, like other communities worldwide, are in the midst of assessing the benefits and challenges of siting wind energy farms. These wind energy projects reflect Michigan’s changing mix of potential energy sources; changes that are requiring the attention of all West Michigan communities.\\u000aMichigan’s electricity providers consider

Erik Edward Nordman

2010-01-01

409

First observations of simultaneous interhemispheric conjugate high-latitude thermospheric winds  

NASA Astrophysics Data System (ADS)

We report the first observations of simultaneous high-latitude interhemispheric F region neutral wind fields by combining the 630 nm optical measurements from two scanning Doppler imagers (SDIs) and three Fabry-Perot interferometers (FPIs) for a period exceeding 5 h. From the Southern Hemisphere, a SDI at Mawson and a FPI at Davis, both in Antarctica, are geomagnetically mapped onto the Northern Hemisphere. These data are combined in the Northern Hemisphere with a SDI at Longyearbyen, Svalbard, and two FPIs near Kiruna in Sweden and Sodankyla in Finland. Geomagnetic conditions were moderate (Kp = 3--3+) and steady although the interplanetary magnetic field Bz component did change polarity several times. There is good agreement between the conjugate 630 nm optical intensities and wind vectors where the two SDIs' fields of view overlap. All wind field vectors are overlaid onto the northern Super Dual Auroral Radar Network ion convection contours. Qualitatively, the agreement between neutral and ion flow is remarkably good throughout the study interval, even down to mesoscale spatial size.

Kosch, M. J.; Anderson, C.; Yiu, H.-C. I.; Kellerman, A. C.; Makarevich, R. A.; Aruliah, A.; Conde, M.; Griffin, E.; Davies, T.; McWhirter, I.; Dyson, P. L.

2010-09-01

410

VectorBase: a data resource for invertebrate vector genomics  

Microsoft Academic Search

VectorBase (http:\\/\\/www.vectorbase.org) is an NIAID-funded Bioinformatic Resource Center focused on invertebrate vectors of human patho- gens. VectorBase annotates and curates vector genomes providing a web accessible integrated resource for the research community. Currently, VectorBase contains genome information for three mosquito species: Aedes aegypti, Anopheles gam- biae and Culex quinquefasciatus, a body louse Pediculus humanus and a tick species Ixodes scapularis.

Daniel Lawson; Peter Arensburger; Peter Atkinson; Nora J. Besansky; Robert V. Bruggner; Ryan Butler; Kathryn S. Campbell; George K. Christophides; Scott Christley; Emmanuel Dialynas; Martin Hammond; Catherine A. Hill; Nathan Konopinski; Neil F. Lobo; Robert M. Maccallum; Gregory R. Madey; Karine Megy; Jason Meyer; Seth Redmond; David W. Severson; Eric O. Stinson; Pantelis Topalis; Ewan Birney; William M. Gelbart; Fotis C. Kafatos; Christos Louis; Frank H. Collins

2009-01-01

411

Visualizing Nonlinear Vector Field Topology  

Microsoft Academic Search

Abstract| We present our results on the visualization of non-linear vector eld topology. The underlying mathemat- ics is done in Cliord algebra, a system describing geometry by extending the usual vector space by a multiplication of vectors. We started with the observation that all known algorithms for vector eld topology are based on piecewise linear or bilinear approximation and that

Gerik Scheuermann; Heinz Krüger; Martin Menzel; Alyn P. Rockwood

1998-01-01

412

Windkraft. (Wind power).  

National Technical Information Service (NTIS)

For Schleswig-Holstein, wind energy is the most interesting renewable energy source because the country with its permanent winds is an extensive 'strong wind area'. Therefore, the government significantly emphasizes the development of wind power. The obje...

1989-01-01

413

Wind Power Machines.  

National Technical Information Service (NTIS)

Basic aerodynamic features of wind power and wind wheels are discussed. The adaptation of wind power to running machinery is described. Developments in wind power are illustrated, followed by a brief outline of operating properties. (Author)

U. Hutter

1975-01-01

414

Wind power machines  

Microsoft Academic Search

Basic aerodynamic features of wind power and wind wheels are discussed. The adaptation of wind power to running machinery is described. Developments in wind power are illustrated, followed by a brief outline of operating properties.

U. Hutter

1975-01-01

415

Magnetar Winds  

NASA Astrophysics Data System (ADS)

We assume that magnetars - pulsar-like objects with extremely high (around 1015 G) magnetic fields - drive relativistic MHD winds which are Poynting flux dominated. For a non-aligned rotator, the field structure will resemble a Parker spiral. In the pulsar case, such striped winds have been discussed by Coroniti [1], Michel [2] and Lyubarsky and Kirk [3]. We compute the radiation from the reconnection zones of these winds for parameters appropriate to magnetars and discuss the results in the context of Gamma-Ray Burst theories. References: [1] Coroniti, F.V. 1990, ApJ, 349, 538 [2] Michel, F.C. 1994 ApJ, 431, 397 [3] Lyubarsky, Y. & Kirk, J.G., 2001, ApJ, 547, 437

Guthmann, A. W.; Skjæraasen, O.; Kirk, J. G.

416

Comparison between QuikSCAT and buoy wind data in the Ligurian Sea  

Microsoft Academic Search

Wind above sea surface plays an important role in the Mediterranean Sea for a large variety of scientific applications (i.e., climatological, meteorological and oceanographic studies). In this work we compare wind vectors obtained from the SeaWinds scatterometer on board the National Aeronautics and Space Ad