Science.gov

Sample records for katrinas wind fields

  1. Hurricane Katrina Wind Investigation Report

    SciTech Connect

    Desjarlais, A. O.

    2007-08-15

    This investigation of roof damage caused by Hurricane Katrina is a joint effort of the Roofing Industry Committee on Weather Issues, Inc. (RICOWI) and the Oak Ridge National Laboratory/U.S. Department of Energy (ORNL/DOE). The Wind Investigation Program (WIP) was initiated in 1996. Hurricane damage that met the criteria of a major windstorm event did not materialize until Hurricanes Charley and Ivan occurred in August 2004. Hurricane Katrina presented a third opportunity for a wind damage investigation in August 29, 2005. The major objectives of the WIP are as follows: (1) to investigate the field performance of roofing assemblies after major wind events; (2) to factually describe roofing assembly performance and modes of failure; and (3) to formally report results of the investigations and damage modes for substantial wind speeds The goal of the WIP is to perform unbiased, detailed investigations by credible personnel from the roofing industry, the insurance industry, and academia. Data from these investigations will, it is hoped, lead to overall improvement in roofing products, systems, roofing application, and durability and a reduction in losses, which may lead to lower overall costs to the public. This report documents the results of an extensive and well-planned investigative effort. The following program changes were implemented as a result of the lessons learned during the Hurricane Charley and Ivan investigations: (1) A logistics team was deployed to damage areas immediately following landfall; (2) Aerial surveillance--imperative to target wind damage areas--was conducted; (3) Investigation teams were in place within 8 days; (4) Teams collected more detailed data; and (5) Teams took improved photographs and completed more detailed photo logs. Participating associations reviewed the results and lessons learned from the previous investigations and many have taken the following actions: (1) Moved forward with recommendations for new installation procedures

  2. Gone with the Wind? Integrity and Hurricane Katrina

    ERIC Educational Resources Information Center

    Lucas, Frances; Katz, Brit

    2011-01-01

    Hurricane Katrina slammed into 80 miles of Mississippi shoreline on August 29, 2005. It was the nation's worst natural disaster, a perfect storm. One hundred sixty miles-per-hour winds sent 55-foot-tall waves and a 30-foot wall of water across the shore and miles inland. It displaced 400,000 residents along the coast of the Mississippi, and…

  3. Tropical Storm Katrina

    Atmospheric Science Data Center

    2014-05-15

    ... title:  Cloud Spirals and Outflow in Tropical Storm Katrina     View Larger Image ... heights and cloud-tracked wind velocities for Tropical Storm Katrina, as the center of the storm was situated over the Tennessee ...

  4. Katrina's Wake

    NASA Astrophysics Data System (ADS)

    Bossak, Brian H.

    2005-09-01

    Residents and community leaders in New Orleans, Louisiana,``the Big Easy,'' have long feared the ``Big One,'' the almost-mythical ``übercane'' predicted to one day destroy the city in a torrent of rushing water and violent winds. On the morning of Monday, 29 August 2005, Hurricane Katrina made landfall as a Category 4 storm on the Saffir-Simpson scale, first to the south of New Orleans along the Mississippi delta, and then just to the east of New Orleans near Bay St. Louis, Mississippi. Only hours earlier, Hurricane Katrina, which weakened before landfall, had possessed sustained winds of 281 kph, with gusts over 321 kph.

  5. Evaluation of Vertically Resolved Water Winds from AIRS using Hurricane Katrina

    NASA Technical Reports Server (NTRS)

    Aumann, Hartmut H.; Dobkowski, Edwin C.; Gregorich, David T.

    2005-01-01

    The knowledge of wind velocity as a function of altitude is key to weather forecast improvements. The ability of hyperspectral sounders in principle to measure vertically resolved water winds, which has long been recognized, has been tested with Atmospheric Infrared Sounder (AIRS) data. AIRS retrievals of total column water above 300 mb have been correlated with the radiosonde upper-tropospheric wind velocity and moisture data. The excellent correlation is illustrated with results obtained from hurricane Katrina and from the western United States. AIRS is a hyperspectral infrared sounder in low Earth orbit. It was launched in May 2002. We illustrate the use of AIRS data for the measurement of upper tropospheric water by using the 2387/cm CO2 R-branch channel and the 1551/cm water vapor channel. The 2387/cm channel measures the temperature at 300 mb totally independent of water vapor. The weighting function of the 1551/cm channel peaks at 300 mb only under moist conditions; the peak shifts downward (higher temperature) for less water and upward (lower temperature) for more water. The difference between the brightness temperatures bt2387 and bt1551 cancels the local several degree weather related variability of the temperature and measures the component due to the water vapor at 300 mb.

  6. Solar Wind Magnetic Fields

    NASA Technical Reports Server (NTRS)

    Smith, E. J.

    1995-01-01

    The magnetic fields originate as coronal fields that are converted into space by the supersonic, infinitely conducting, solar wind. On average, the sun's rotation causes the field to wind up and form an Archimedes Spiral. However, the field direction changes almost continuously on a variety of scales and the irregular nature of these changes is often interpreted as evidence that the solar wind flow is turbulent.

  7. Surviving Hurricane Katrina: Winds of Change Transform a New Orleans Addiction Treatment Agency

    ERIC Educational Resources Information Center

    Toriello, Paul J.; Pedersen-Wasson, Else; Crisham, Erin M.; Ellis, Robert; Morse, Patricia; Morse, Edward V.

    2007-01-01

    Hurricane Katrina's impact on the operations of the largest residential, addiction treatment organization in New Orleans is described. Pre- and post-Katrina experiences are discussed and augmented with organizational performance data. Suggestions for future research are provided. (Contains 4 figures.)

  8. Hurricane Katrina

    Atmospheric Science Data Center

    2014-05-15

    article title:  Flooding in the Aftermath of Hurricane Katrina   ... River that was not apparent before Katrina. The post-Katrina flooding along the edges of Lake Pontchartrain and the city of New Orleans is ...

  9. Modeling Hurricane Katrina's merchantable timber and wood damage in south Mississippi using remotely sensed and field-measured data

    NASA Astrophysics Data System (ADS)

    Collins, Curtis Andrew

    Ordinary and weighted least squares multiple linear regression techniques were used to derive 720 models predicting Katrina-induced storm damage in cubic foot volume (outside bark) and green weight tons (outside bark). The large number of models was dictated by the use of three damage classes, three product types, and four forest type model strata. These 36 models were then fit and reported across 10 variable sets and variable set combinations for volume and ton units. Along with large model counts, potential independent variables were created using power transforms and interactions. The basis of these variables was field measured plot data, satellite (Landsat TM and ETM+) imagery, and NOAA HWIND wind data variable types. As part of the modeling process, lone variable types as well as two-type and three-type combinations were examined. By deriving models with these varying inputs, model utility is flexible as all independent variable data are not needed in future applications. The large number of potential variables led to the use of forward, sequential, and exhaustive independent variable selection techniques. After variable selection, weighted least squares techniques were often employed using weights of one over the square root of the pre-storm volume or weight of interest. This was generally successful in improving residual variance homogeneity. Finished model fits, as represented by coefficient of determination (R2), surpassed 0.5 in numerous models with values over 0.6 noted in a few cases. Given these models, an analyst is provided with a toolset to aid in risk assessment and disaster recovery should Katrina-like weather events reoccur.

  10. Hurricane Katrina

    Atmospheric Science Data Center

    2013-01-08

    ... Mississippi regions were acquired before and one day after Katrina made landfall along the Gulf of Mexico coast, and highlight many of the ... http://eosweb.larc.nasa.gov/HPDOCS/misr/misr_html/hurricane_katrina_flood.html ...

  11. Children's mental health care following Hurricane Katrina: a field trial of trauma-focused psychotherapies.

    PubMed

    Jaycox, Lisa H; Cohen, Judith A; Mannarino, Anthony P; Walker, Douglas W; Langley, Audra K; Gegenheimer, Kate L; Scott, Molly; Schonlau, Matthias

    2010-04-01

    New Orleans school children participated in an assessment and field trial of two interventions 15 months after Hurricane Katrina. Children (N = 195) reported on hurricane exposure, lifetime trauma exposure, peer and parent support, posttraumatic stress disorder (PTSD), and depressive symptoms. Teachers reported on behavior. At baseline, 60.5% screened positive for PTSD symptoms and were offered a group intervention at school or individual treatment at a mental health clinic. Uptake of the mental health care was uneven across intervention groups, with 98% beginning the school intervention, compared to 37% beginning at the clinic. Both treatments led to significant symptom reduction of PTSD symptoms, but many still had elevated PTSD symptoms at posttreatment. Implications for future postdisaster mental health work are discussed.

  12. Time dependent wind fields

    NASA Technical Reports Server (NTRS)

    Chelton, D. B.

    1986-01-01

    Two tasks were performed: (1) determination of the accuracy of Seasat scatterometer, altimeter, and scanning multichannel microwave radiometer measurements of wind speed; and (2) application of Seasat altimeter measurements of sea level to study the spatial and temporal variability of geostrophic flow in the Antarctic Circumpolar Current. The results of the first task have identified systematic errors in wind speeds estimated by all three satellite sensors. However, in all cases the errors are correctable and corrected wind speeds agree between the three sensors to better than 1 ms sup -1 in 96-day 2 deg. latitude by 6 deg. longitude averages. The second task has resulted in development of a new technique for using altimeter sea level measurements to study the temporal variability of large scale sea level variations. Application of the technique to the Antarctic Circumpolar Current yielded new information about the ocean circulation in this region of the ocean that is poorly sampled by conventional ship-based measurements.

  13. Project Katrina

    ERIC Educational Resources Information Center

    Aghayan, Carol; Schellhaas, Andree; Wayne, Angela; Burts, Diane C.; Buchanan, Teresa K.; Benedict, Joan

    2005-01-01

    This article describes a spontaneous project that emerged from a group of 3- and 4-year-old children in Louisiana after Hurricane Katrina. The article describes how the teachers adapted the classroom and curriculum to meet the diverse needs of children who were evacuees, as well as those children who were affected in other ways by the…

  14. The Winds of Katrina Still Call Our Names: How Do Teachers and Schools Confront Social Justice Issues?

    ERIC Educational Resources Information Center

    Wynne, Joan T.

    2007-01-01

    Certainly, individuals in many colleges and public schools address the impact of race, class, and power on schools, yet the institutions as a whole continue, even a year after Katrina, to ignore the imperative to explicitly and consistently deal with these issues. Human justice must become an institutional mantra, not just the conversation of a…

  15. Response of dominant wind wave fields to abrupt wind increase

    NASA Astrophysics Data System (ADS)

    Caulliez, Guillemette

    2013-04-01

    Over the last decades, significant progress has been made in modelling wave field development by wind observed at sea, based on more elaborated numerical schemes and refined parametrizations of wind energy input and wave dissipation. In such models, the wind wave growth in space or time is generally governed by the average wind speed evaluated at one reference level and the natural wind speed variability is neglected. However, the impact of this assumption is not really known, mainly because of the lack of appropriate observations. To revisit this question, we report a detailed laboratory investigation aimed at describing the dominant wave field evolution resulting from an abrupt local wind speed increase. The experiments were conducted in the large Marseille-Luminy wind wave tank for moderate to high wind conditions. At 23 m fetch, a contraction of the wind tunnel section by a convergent profile created a spatial wind speed acceleration over a distance of about 2 m. Downwind, the wind speed, enhanced by a factor 1.4, was kept constant up to the end of the water tank. The wind wave field development induced by such a "wind gust" was investigated at successive fetches by wave probes and compared to those observed at similar fetches for homogeneous wind conditions. When wind increases, these observations first revealed no dramatic change in the evolution of the dominant spectral peak with fetch. The dominant wave energy which increases slowly for constant wind conditions, follows the wind speed but with a significant space lag. For well-established gravity wave fields, the space relaxation scales which describe this evolution do not depend noticeably on wind, all the curves collapse into a single one when wave quantities are normalized by their value observed just upstream the convergent profile. The wave growth rate observed for the new equilibrium state can be described by the Hasselman et al. (1973) relationship but with an "equivalent'' shorter fetch since, in

  16. Wind Turbines Adaptation to the Variability of the Wind Field

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

    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

  17. LIDAR Wind Speed Measurements of Evolving Wind Fields

    SciTech Connect

    Simley, E.; Pao, L. Y.

    2012-07-01

    Light Detection and Ranging (LIDAR) systems are able to measure the speed of incoming wind before it interacts with a wind turbine rotor. These preview wind measurements can be used in feedforward control systems designed to reduce turbine loads. However, the degree to which such preview-based control techniques can reduce loads by reacting to turbulence depends on how accurately the incoming wind field can be measured. Past studies have assumed Taylor's frozen turbulence hypothesis, which implies that turbulence remains unchanged as it advects downwind at the mean wind speed. With Taylor's hypothesis applied, the only source of wind speed measurement error is distortion caused by the LIDAR. This study introduces wind evolution, characterized by the longitudinal coherence of the wind, to LIDAR measurement simulations to create a more realistic measurement model. A simple model of wind evolution is applied to a frozen wind field used in previous studies to investigate the effects of varying the intensity of wind evolution. LIDAR measurements are also evaluated with a large eddy simulation of a stable boundary layer provided by the National Center for Atmospheric Research. Simulation results show the combined effects of LIDAR errors and wind evolution for realistic turbine-mounted LIDAR measurement scenarios.

  18. Wide Area Wind Field Monitoring Status & Results

    SciTech Connect

    Alan Marchant; Jed Simmons

    2011-09-30

    Volume-scanning elastic has been investigated as a means to derive 3D dynamic wind fields for characterization and monitoring of wind energy sites. An eye-safe volume-scanning lidar system was adapted for volume imaging of aerosol concentrations out to a range of 300m. Reformatting of the lidar data as dynamic volume images was successfully demonstrated. A practical method for deriving 3D wind fields from dynamic volume imagery was identified and demonstrated. However, the natural phenomenology was found to provide insufficient aerosol features for reliable wind sensing. The results of this study may be applicable to wind field measurement using injected aerosol tracers.

  19. LIDAR Wind Speed Measurements of Evolving Wind Fields

    SciTech Connect

    Simley, E.; Pao, L. Y.; Kelley, N.; Jonkman, B.; Frehlich, R.

    2012-01-01

    Light Detection and Ranging (LIDAR) systems are able to measure the speed of incoming wind before it interacts with a wind turbine rotor. These preview wind measurements can be used in feedforward control systems that are designed to reduce turbine loads. However, the degree to which such preview-based control techniques can reduce loads by reacting to turbulence depends on how accurately the incoming wind field can be measured. Past studies have assumed the validity of physicist G.I. Taylor's 1938 frozen turbulence hypothesis, which implies that turbulence remains unchanged as it advects downwind at the mean wind speed. With Taylor's hypothesis applied, the only source of wind speed measurement error is distortion caused by the LIDAR. This study introduces wind evolution, characterized by the longitudinal coherence of the wind, to LIDAR measurement simulations using the National Renewable Energy Laboratory's (NREL's) 5-megawatt turbine model to create a more realistic measurement model. A simple model of wind evolution was applied to a frozen wind field that was used in previous studies to investigate the effects of varying the intensity of wind evolution. LIDAR measurements were also evaluated using a large eddy simulation (LES) of a stable boundary layer that was provided by the National Center for Atmospheric Research. The LIDAR measurement scenario investigated consists of a hub-mounted LIDAR that scans a circle of points upwind of the turbine in order to estimate the wind speed component in the mean wind direction. Different combinations of the preview distance that is located upwind of the rotor and the radius of the scan circle were analyzed. It was found that the dominant source of measurement error for short preview distances is the detection of transverse and vertical wind speeds from the line-of-sight LIDAR measurement. It was discovered in previous studies that, in the absence of wind evolution, the dominant source of error for large preview distances

  20. Erosion by Wind: Field Measurement

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wind erosion and deposition results when wind moves soil from a bare susceptible surface to another location downwind. Although placement of permanent vertical references such as pins or rods has been used to measure soil redistribution, it is more commonly measured by capturing sediment moving dur...

  1. Parallel electric fields from ionospheric winds

    NASA Technical Reports Server (NTRS)

    Nakada, M. P.

    1987-01-01

    The possible production of electric fields parallel to the magnetic field by dynamo winds in the E region is examined, using a jet stream wind model. Current return paths through the F region above the stream are examined as well as return paths through the conjugate ionosphere. The Wulf geometry with horizontal winds moving in opposite directions one above the other is also examined. Parallel electric fields are found to depend strongly on the width of current sheets at the edges of the jet stream. If these are narrow enough, appreciable parallel electric fields are produced.

  2. Ocean Wave Simulation Based on Wind Field.

    PubMed

    Li, Zhongyi; Wang, Hao

    2016-01-01

    Ocean wave simulation has a wide range of applications in movies, video games and training systems. Wind force is the main energy resource for generating ocean waves, which are the result of the interaction between wind and the ocean surface. While numerous methods to handle simulating oceans and other fluid phenomena have undergone rapid development during the past years in the field of computer graphic, few of them consider to construct ocean surface height field from the perspective of wind force driving ocean waves. We introduce wind force to the construction of the ocean surface height field through applying wind field data and wind-driven wave particles. Continual and realistic ocean waves result from the overlap of wind-driven wave particles, and a strategy was proposed to control these discrete wave particles and simulate an endless ocean surface. The results showed that the new method is capable of obtaining a realistic ocean scene under the influence of wind fields at real time rates. PMID:26808718

  3. Ocean Wave Simulation Based on Wind Field.

    PubMed

    Li, Zhongyi; Wang, Hao

    2016-01-01

    Ocean wave simulation has a wide range of applications in movies, video games and training systems. Wind force is the main energy resource for generating ocean waves, which are the result of the interaction between wind and the ocean surface. While numerous methods to handle simulating oceans and other fluid phenomena have undergone rapid development during the past years in the field of computer graphic, few of them consider to construct ocean surface height field from the perspective of wind force driving ocean waves. We introduce wind force to the construction of the ocean surface height field through applying wind field data and wind-driven wave particles. Continual and realistic ocean waves result from the overlap of wind-driven wave particles, and a strategy was proposed to control these discrete wave particles and simulate an endless ocean surface. The results showed that the new method is capable of obtaining a realistic ocean scene under the influence of wind fields at real time rates.

  4. Ocean Wave Simulation Based on Wind Field

    PubMed Central

    2016-01-01

    Ocean wave simulation has a wide range of applications in movies, video games and training systems. Wind force is the main energy resource for generating ocean waves, which are the result of the interaction between wind and the ocean surface. While numerous methods to handle simulating oceans and other fluid phenomena have undergone rapid development during the past years in the field of computer graphic, few of them consider to construct ocean surface height field from the perspective of wind force driving ocean waves. We introduce wind force to the construction of the ocean surface height field through applying wind field data and wind-driven wave particles. Continual and realistic ocean waves result from the overlap of wind-driven wave particles, and a strategy was proposed to control these discrete wave particles and simulate an endless ocean surface. The results showed that the new method is capable of obtaining a realistic ocean scene under the influence of wind fields at real time rates. PMID:26808718

  5. Solar winds along curved magnetic field lines

    NASA Astrophysics Data System (ADS)

    Li, B.; Xia, L. D.; Chen, Y.

    2011-05-01

    Context. Both remote-sensing measurements using the interplanetary scintillation (IPS) technique and in-situ measurements by the Ulysses spacecraft show a bimodal structure for the solar wind at solar minimum conditions. At present it still remains to address why the fast wind is fast and the slow wind is slow. While a robust empirical correlation exists between the coronal expansion rate fc of the flow tubes and the speeds v measured in situ, a more detailed data analysis suggests that v depends on more than just fc. Aims. We examine whether the non-radial shape of field lines, which naturally accompanies any non-radial expansion, could be an additional geometrical factor. Methods. We solved the transport equations incorporating the heating from turbulent Alfvén waves for an electron-proton solar wind along curved field lines given by an analytical magnetic field model, which is representative of a solar minimum corona. Results. The field line shape is found to influence the solar wind parameters substantially, reducing the asymptotic speed by up to ~130 km s-1 or by ~28% in relative terms, compared with the case where the field line curvature is neglected. This effect was interpreted in the general framework of energy addition in the solar wind: compared to the straight case, the field line curvature enhances the effective energy deposition to the subsonic flow, which results in a higher proton flux and a lower terminal proton speed. Conclusions. Our computations suggest that the field line curvature could be a geometrical factor which, in addition to the tube expansion, substantially influences the solar wind speed. Furthermore, although the field line curvature is unlikely to affect the polar fast solar wind at solar minima, it does help make the wind at low latitudes slow, which in turn helps better reproduce the Ulysses measurements.

  6. Wavelet analysis for wind fields estimation.

    PubMed

    Leite, Gladeston C; Ushizima, Daniela M; Medeiros, Fátima N S; de Lima, Gilson G

    2010-01-01

    Wind field analysis from synthetic aperture radar images allows the estimation of wind direction and speed based on image descriptors. In this paper, we propose a framework to automate wind direction retrieval based on wavelet decomposition associated with spectral processing. We extend existing undecimated wavelet transform approaches, by including à trous with B(3) spline scaling function, in addition to other wavelet bases as Gabor and Mexican-hat. The purpose is to extract more reliable directional information, when wind speed values range from 5 to 10 ms(-1). Using C-band empirical models, associated with the estimated directional information, we calculate local wind speed values and compare our results with QuikSCAT scatterometer data. The proposed approach has potential application in the evaluation of oil spills and wind farms.

  7. Wavelet Analysis for Wind Fields Estimation

    PubMed Central

    Leite, Gladeston C.; Ushizima, Daniela M.; Medeiros, Fátima N. S.; de Lima, Gilson G.

    2010-01-01

    Wind field analysis from synthetic aperture radar images allows the estimation of wind direction and speed based on image descriptors. In this paper, we propose a framework to automate wind direction retrieval based on wavelet decomposition associated with spectral processing. We extend existing undecimated wavelet transform approaches, by including à trous with B3 spline scaling function, in addition to other wavelet bases as Gabor and Mexican-hat. The purpose is to extract more reliable directional information, when wind speed values range from 5 to 10 ms−1. Using C-band empirical models, associated with the estimated directional information, we calculate local wind speed values and compare our results with QuikSCAT scatterometer data. The proposed approach has potential application in the evaluation of oil spills and wind farms. PMID:22219699

  8. Wavelet analysis for wind fields estimation.

    PubMed

    Leite, Gladeston C; Ushizima, Daniela M; Medeiros, Fátima N S; de Lima, Gilson G

    2010-01-01

    Wind field analysis from synthetic aperture radar images allows the estimation of wind direction and speed based on image descriptors. In this paper, we propose a framework to automate wind direction retrieval based on wavelet decomposition associated with spectral processing. We extend existing undecimated wavelet transform approaches, by including à trous with B(3) spline scaling function, in addition to other wavelet bases as Gabor and Mexican-hat. The purpose is to extract more reliable directional information, when wind speed values range from 5 to 10 ms(-1). Using C-band empirical models, associated with the estimated directional information, we calculate local wind speed values and compare our results with QuikSCAT scatterometer data. The proposed approach has potential application in the evaluation of oil spills and wind farms. PMID:22219699

  9. Wind gust models derived from field data

    NASA Technical Reports Server (NTRS)

    Gawronski, W.

    1995-01-01

    Wind data measured during a field experiment were used to verify the analytical model of wind gusts. Good coincidence was observed; the only discrepancy occurred for the azimuth error in the front and back winds, where the simulated errors were smaller than the measured ones. This happened because of the assumption of the spatial coherence of the wind gust model, which generated a symmetric antenna load and, in consequence, a low azimuth servo error. This result indicates a need for upgrading the wind gust model to a spatially incoherent one that will reflect the real gusts in a more accurate manner. In order to design a controller with wind disturbance rejection properties, the wind disturbance should be known at the input to the antenna rate loop model. The second task, therefore, consists of developing a digital filter that simulates the wind gusts at the antenna rate input. This filter matches the spectrum of the measured servo errors. In this scenario, the wind gusts are generated by introducing white noise to the filter input.

  10. Near-ground tornado wind fields

    SciTech Connect

    McDonald, J.R.

    1984-07-01

    A study of near-ground tornado wind fields has been conducted by inspecting damage and debris patterns found in tornado damage paths. Because there were no significant tornado events (F4 or greater) during the contract performance period, data from the literature and the files of the Institute for Disaster Research were used to perform the analyses. The results indicate: (1) maximum tornado wind speed ever experienced or expected is in the range of 250 to 300 mph; (2) appearance of damage, taken by itself, is a misleading parameter of tornado intensity. Type of construction, age of construction, materials and other construction features significantly affect structural performance of a building subjected to wind loads and should be taken into account in assigning Fujita-Scale ratings; (3) damage to forests gives a good indication of tornado wind field flow patterns, but do not give verifiable values of wind speed; (4) factors such as translational speed, wind direction and path width affect appearance of damage or a tornado; and (5) even the most awesome appearing missiles do not require incredible wind speeds to explain them. Some progress in computer simulation of tornado missiles have been made. 31 references, 8 figures, 2 tables.

  11. Recovering from Hurricane Katrina

    ERIC Educational Resources Information Center

    Coleman, Nadine

    2006-01-01

    The Gulf Coast region suffered an unusually severe hurricane season in 2005: Hurricane Katrina (August 28-29, 2005) devastated much of southern Mississippi and Louisiana. Approximately 2,700 licensed early care and education facilities in those states and in Alabama were affected by Katrina, in addition to an unknown number of family child care…

  12. Langley Field wind tunnel apparatus

    NASA Technical Reports Server (NTRS)

    Bacon, D L

    1921-01-01

    The difficulties experienced in properly holding thin tipped or tapered airfoils while testing on an N.P.L. type aerodynamic balance even at low air speeds, and the impossibility of holding even solid metal models at the high speeds attainable at the National Advisory Committee's wind tunnel, necessitated the design of a balance which would hold model airfoils of any thickness and at speeds up to 150 m.p.h. In addition to mechanical strength and rigidity, it was highly desirable that the balance readings should require a minimum amount of correction and mathematical manipulation in order to obtain the lift and drag coefficients and the center of pressure. The balance described herein is similar to one in use at the University of Gottingen, the main difference lying in the addition of a device for reading the center of pressure directly, without the necessity of any correction whatsoever. Details of the design and operation of the device are given.

  13. Continuity, social change and Katrina.

    PubMed

    Henry, Jacques

    2011-01-01

    For some time, disaster researchers have looked for social change and mostly found continuity. This paper argues that shifting the focus from investigating social change to documenting continuity may enhance the understanding and planning of post-disaster situations especially in industrialised societies like the United States. Drawing from qualitative data from post-Katrina New Orleans, it proposes using the concept of continuity as an analytical device both to identify the axes of continuity and evaluate the likelihood and possible dimensions of social change. The analysis of long-term recovery plans, along with field observations and interviews with evacuees, suggest that despite the well-documented emergence of conflict in post-Katrina New Orleans, the likelihood of social change appears limited.

  14. Parallel electric fields from ionospheric winds

    SciTech Connect

    Nakada, M.P. )

    1987-10-01

    The possible production of electric fields parallel to the magnetic field by dynamo winds in the E region is examined, using a jet stream wind model. Current return paths through the F region above the stream are examined as well as return paths through the conjugate ionosphere. The Wulf geometry with horizontal winds moving in opposite directions one above the other is also examined. Parallel electric fields are found to depend strongly on the width of current sheets at the edges of the jet stream. If these are narrow enough, appreciable parallel electric fields are produced. These appear to be sufficient to heat the electrons which reduces the conductivity and produces further increases in parallel electric fields and temperatures. Calculations indicate that high enough temperatures for optical emission can be produced in less than 0.3 s. Some properties of auroras that might be produced by dynamo winds are examined; one property is a time delay in brightening at higher and lower altitudes.

  15. Cooperative field test program for wind systems

    SciTech Connect

    Bollmeier, W.S. II; Dodge, D.M.

    1992-03-01

    The objectives of the Federal Wind Energy Program, managed by the US Department of Energy (DOE), are (1) to assist industry and utilities in achieving a multi-regional US market penetration of wind systems, and (2) to establish the United States as the world leader in the development of advanced wind turbine technology. In 1984, the program conducted a series of planning workshops with representatives from the wind energy industry to obtain input on the Five-Year Research Plan then being prepared by DOE. One specific suggestion that came out of these meetings was that the federal program should conduct cooperative research tests with industry to enhance the technology transfer process. It was also felt that the active involvement of industry in DOE-funded research would improve the state of the art of wind turbine technology. DOE established the Cooperative Field Test Program (CFTP) in response to that suggestion. This program was one of the first in DOE to feature joint industry-government research test teams working toward common objectives.

  16. Construction of surface pressure field from scatterometer wind field

    NASA Technical Reports Server (NTRS)

    Wurtele, Morton G.; Hsu, Carol H.; Cunningham, Glen F.; Woiceshyn, Peter M.

    1989-01-01

    An account of the construction of surface pressure fields from Seasat-A satellite scatterometer (SASS) winds as carried out by different methods, and the comparison of these pressure fields with those derived from in situ ship observations is presented. On the assumption that the pressure adjusts itself instantaneously to the motion field, it may be computed by various methods. One of these makes use of planetary boundary theory, and of the possible techniques in this category a two-layer iterative scheme admitting of the parametrization of diabatic and baroclinic effects and of secondary flow was chosen. A second method involves the assumption of zero two-dimensional divergence, leading to a Laplace's equation (the balance equation) in pressure, with the wind field serving as a forcing function. This method does not accommodate adiabatic or baroclinic effects, and requires a knowledge of the pressure at all boundary points. Two comparison fields are used for validation: the conventional operational analyses of the US National Meteorological Center (NMC), and the special analyses of the Gulf of Alaska Experiment (GOASEX), which were done by hand. The results of the computations were as follows: (1) The pressure fields, as computed from the SASS winds alone, closely approximated the NMC fields in regions where reasonable in situ coverage was available (typically, one or two mb differences over most of the chart, three to four mb in extreme cases); (2) In some cases the SASS-derived pressure fields displayed high-resolution phenomena not detected by the NMC fields, but evident in the GOASEX data; and, (3) As expected, the pressure fields derived from the balance equation were much smoother and less well resolved than the SASS-derived or NMC fields. The divergence as measured from the SASS winds is smaller than, but of the same order of magnitude as, the vorticity.

  17. The relationship between hurricane wind fields and the associated disturbance in US forest ecosystems

    NASA Astrophysics Data System (ADS)

    Negron Juarez, R. I.; Chambers, J. Q.; Hurtt, G. C.; Fisk, J. P.

    2011-12-01

    Tropical cyclones are recurrent in the U. S. Gulf Coast and produce drastic disturbance to the forest ecosystem by altering forest structure, species composition, nutrient cycling, biomass accumulation, etc. The recurrent characteristics of these events demand a rapid yet reliable assessment of forest disturbance in order to provide better management decisions, as well as to evaluate damage to the landscape, biomass loss and the associated impacts to the regional carbon budget. In this study we present a methodology for rapid assessment of forest disturbance produced by tropical cyclones based on maximum sustained wind swaths (H*wind), MODIS (Moderate Resolution Imaging Spectroradiometer)-derived disturbances and field-measured tree mortality collected in Gulf Coast forests. MODIS images in May (the month of maximum greenness) before the disturbance and in May of the year following the disturbance were processed using spectral mixture analysis (SMA) using image derived end-members. The changes in non-photosynthetic vegetation (ΔNPV, related to wood, dead vegetation and surface litter) from one year to the next was used as the disturbance metric. A strong correlation was found between H*wind and MODIS ΔNPV for hurricanes Charley (2004), Katrina (2005), Rita (2005), and Gustav (2008). In turn, MODIS ΔNPV was shown to have a strong correlation with field-measured mortality. The forest disturbance estimates based on hurricane wind-field and MODIS ΔNPV agree with those published in our previous studies. This study establishes an important relationship that could be incorporated into earth system models to improve our understanding of the effect of tropical cyclones on terrestrial ecosystems and their associated feedbacks within the climate system.

  18. Field verification program for small wind turbines

    SciTech Connect

    Windward Engineering, LLC

    2003-11-30

    In 1999 Windward Engineering (Windward) was awarded a Cooperative Agreement under the Field Verification Program with the Department of Energy (DOE) to install two Whisper H40 wind turbines, one at the NREL National Wind Technology Center (NWTC) and one at a test site near Spanish Fork, Utah. After installation, the turbine at the NWTC was to be operated, maintained, and monitored by NREL while the turbine in Spanish Fork was to be administered by Windward. Under this award DOE and Windward defined the primary objectives of the project as follows: (1) Determine and demonstrate the reliability and energy production of a furling wind turbine at a site where furling will be a very frequent event and extreme gusts can be expected during the duration of the tests. (2) Make engineering measurements and conduct limited computer modeling of the furling behavior to improve the industry understanding of the mechanics and nature of furling. We believe the project has achieved these objectives. The turbine has operated for approximately three and a half years. We have collected detailed engineering data approximately 75 percent of that time. Some of these data were used in an ADAMS model validation that highlighted the accuracies and inaccuracies of the computer modeling for a passively furling wind turbine. We also presented three papers at the American Wind Energy Association (AWEA) Windpower conferences in 2001, 2002, and 2003. These papers addressed the following three topics: (a) general overview of the project [1], (b) furling operation during extreme wind events [2], and (c) extrapolation of extreme (design) loads [3]. We believe these papers have given new insight into the mechanics and nature of furling and have set the stage for future research. In this final report we will highlight some of the more interesting aspects of the project as well as summarize the data for the entire project. We will also present information on the installation of the turbines as well as

  19. Katrina Retrospective: 5 Years Later

    NASA Video Gallery

    Five years after Hurricane Katrina struck the Gulf Coast, NASA revisits the storm with a short video that shows Katrina as captured by satellites. Before and during the hurricane's landfall, NASA p...

  20. Convection electric fields and polar thermospheric winds.

    NASA Technical Reports Server (NTRS)

    Fedder, J. A.; Banks, P. M.

    1972-01-01

    Use of the qualitative ideas of convection electric fields over the earth's polar regions to demonstrate the importance of ion drag in establishing a thermospheric wind system. Recent measurements indicate that uniform electric fields of 10 to 40 mV/m are a regular feature of the polar-cap ionosphere. Calculations of the neutral thermospheric wind, using these measured fields in a simple ionospheric model, have been made. The time scale for motion of the neutral gas ranges from less than 1 hour at F-region heights to about 2 hours in the dynamo region of the ionosphere. It has been found that the viscosity of the atmosphere is important in determining the winds in the dynamo region. Results are given that show ion-temperature enhancements of hundreds of degrees that are due to ion-neutral frictional effects. In addition, the total deposition rate of convection energy in the polar thermosphere is shown to be of the same order of magnitude as that due to absorption of solar EUV radiation. The implications of these results for the dynamics and energetics of the thermosphere are discussed.

  1. The impact of Ensemble-based data assimilation on the predictability of landfalling Hurricane Katrina (2005)

    NASA Astrophysics Data System (ADS)

    Zhang, H.; Pu, Z.

    2012-12-01

    Accurate forecasts of the track, intensity and structure of a landfalling hurricane can save lives and mitigate social impacts. Over the last two decades, significant improvements have been achieved for hurricane forecasts. However, only a few of studies have emphasized landfalling hurricanes. Specifically, there are difficulties in predicting hurricane landfall due to the uncertainties in representing the atmospheric near-surface conditions in numerical weather prediction models, the complicated interaction between the atmosphere and the ocean, and the multiple-scale dynamical and physical processes accompanying storm development. In this study, the impact of the assimilation of conventional and satellite observations on the predictability of landfalling hurricanes is examined by using a mesoscale community Weather Research and Forecasting (WRF) model and an ensemble Kalman filter developed by NCAR Data Assimilation Research Testbed (DART). Hurricane Katrina (2005) was chosen as a case study since it was one of the deadliest disasters in US history. The minimum sea level pressure from the best track, QuikScat ocean surface wind vectors, surface mesonet observations, airborne Doppler radar derived wind components and available conventional observations are assimilated in a series of experiments to examine the data impacts on the predictability of Hurricane Katrina. The analyses and forecasts show that ensemble-based data assimilation significantly improves the forecast of Hurricane Katrina. The assimilation improves the track forecast through modifying the storm structures and related environmental fields. Cyclonic increments are clearly seen in vorticity and wind analyses. Temperature and humidity fields are also modified by the data assimilation. The changes in relevant fields help organize the structure of the storm, intensify the circulation, and result in a positive impact on the evolution of the storm in both analyses and forecasts. The forecasts in the

  2. Wind Field Measurements With Airborne Doppler Lidar

    NASA Technical Reports Server (NTRS)

    Menzies, Robert T.

    1999-01-01

    In collaboration with lidar atmospheric remote sensing groups at NASA Marshall Space Flight Center and National Oceanic and Atmospheric Administration (NOAA) Environmental Technology Laboratory, we have developed and flown the Multi-center Airborne Coherent Atmospheric Wind Sensor (MACAWS) lidar on the NASA DC-8 research aircraft. The scientific motivations for this effort are: to obtain measurements of subgrid scale (i.e. 2-200 km) processes and features which may be used to improve parameterizations in global/regional-scale models; to improve understanding and predictive capabilities on the mesoscale; and to assess the performance of Earth-orbiting Doppler lidar for global tropospheric wind measurements. MACAWS is a scanning Doppler lidar using a pulsed transmitter and coherent detection; the use of the scanner allows 3-D wind fields to be produced from the data. The instrument can also be radiometrically calibrated and used to study aerosol, cloud, and surface scattering characteristics at the lidar wavelength in the thermal infrared. MACAWS was used to study surface winds off the California coast near Point Arena, with an example depicted in the figure below. The northerly flow here is due to the Pacific subtropical high. The coastal topography interacts with the northerly flow in the marine inversion layer, and when the flow passes a cape or point that juts into the winds, structures called "hydraulic expansion fans" are observed. These are marked by strong variation along the vertical and cross-shore directions. The plots below show three horizontal slices at different heights above sea level (ASL). Bottom plots are enlargements of the area marked by dotted boxes above. The terrain contours are in 200-m increments, with the white spots being above 600-m elevation. Additional information is contained in the original.

  3. Providing continuity of care for chronic diseases in the aftermath of Katrina: from field experience to policy recommendations.

    PubMed

    Arrieta, Martha I; Foreman, Rachel D; Crook, Errol D; Icenogle, Marjorie L

    2009-10-01

    This study sought to elicit challenges and solutions in the provision of health care to those with chronic diseases after Hurricane Katrina in coastal Alabama and Mississippi. In-depth interviews with 30 health and social service providers (key informants) and 4 focus groups with patients with chronic diseases were conducted. Subsequently an advisory panel of key informants was convened. Findings were summarized and key informants submitted additional feedback. The chronic diseases identified as medical management priorities by key informants were mental health, diabetes mellitus, hypertension, respiratory illness, end-stage renal disease, cardiovascular disease, and cancer. The most frequently mentioned barrier to providing care was maintaining continuity of medications. Contributing factors were inadequate information (inaccessible medical records, poor patient knowledge) and financial constraints. Implemented or suggested solutions included relaxation of insurance limitations preventing advance prescription refills; better predisaster patient education to improve medical knowledge; promotion of personal health records; support for information technology systems at community health centers, in particular electronic medical records; improved allocation of donated medications/medical supplies (centralized coordination, decentralized distribution); and networking between local responders and external aid.

  4. Comparison Between Field Data and NASA Ames Wind Tunnel Data

    SciTech Connect

    Corbus, D.

    2005-11-01

    The objective of this analysis is to compare the measured data from the NASA Ames wind tunnel experiment to those collected in the field at the National Wind Technology Center (NWTC) with the same turbine configuration. The results of this analysis provide insight into what measurements can be made in the field as opposed to wind tunnel testing.

  5. Wind loads on flat plate photovoltaic array fields (nonsteady winds)

    NASA Technical Reports Server (NTRS)

    Miller, R. D.; Zimmerman, D. K.

    1981-01-01

    Techniques to predict the dynamic response and the structural dynamic loads of flat plate photovoltaic arrays due to wind turbulence were analyzed. Guidelines for use in predicting the turbulent portion of the wind loading on future similar arrays are presented. The dynamic response and the loads dynamic magnification factor of the two array configurations are similar. The magnification factors at a mid chord and outer chord location on the array illustrated and at four points on the chord are shown. The wind tunnel test experimental rms pressure coefficient on which magnification factors are based is shown. It is found that the largest response and dynamic magnification factor occur at a mid chord location on an array and near the trailing edge. A technique employing these magnification factors and the wind tunnel test rms fluctuating pressure coefficients to calculate design pressure loads due to wind turbulence is presented.

  6. The Astrobiology Field Guide in World Wind

    NASA Astrophysics Data System (ADS)

    Scalice, D. M.

    2004-12-01

    In collaboration with the Australian Centre for Astrobiology (ACA), and NASA Learning Technologies (NLT), and utilizing the powerful visualization capabilities of their "World Wind" software, the NASA Astrobiology Institute (NAI) is crafting a prototype "Astrobiology Field Guide" to bring the field experiences and stories of astrobiology science to the public and classrooms around the world. The prototype focuses on one region in particular - The Pilbara in Western Australia. This first Field Guide "hotspot" is an internationally recognized area hosting the best known example of the earliest evidence of life on Earth - a stromatolitic chert precipitation in the 3.45 Ga Warrawoona Group. The goal of the Astrobiology Field Guide is to engage students of all ages with the ongoing field expeditions of today's astrobiologists as they explore the ends of the Earth searching for clues to life's origin, evolution, and distribution in the Universe. The NAI hopes to expand this Field Guide to include many more astrobiologically relevant areas across the globe such as Cuatro Cienegas in Mexico, the Rio Tinto in Spain, Yellowstone National Park in the US, and the Lost City hydrothermal vent field on the mid-Atlantic ridge - and possibly sites on Mars. To that end, we will be conducting feasibility studies and evaluations with informal and formal education contacts. The Astrobiology Field Guide is also serving as a cornerstone to educational materials being developed focused on the Pilbara region for use in classrooms in Australia, the UK, and potentially the US. These materials are being developed by the Australian Centre for Astrobiology, and the ICT Innovations Centre at Macquarie University in Sydney, in collaboration with the NAI and the Centre for Astronomy and Science Education at the University of Glamorgan in the UK.

  7. Contemplating Katrina's Chaos

    ERIC Educational Resources Information Center

    Roach, Ronald

    2005-01-01

    To get some notion of how deeply scholars have been affected by Hurricane Katrina, one might look to someone like Dr. Erma Lawson, a medical sociologist from the University of North Texas. Lawson, who has coordinated the assistance efforts for the Association of Black Sociologists, has not hesitated to call on colleagues, graduate students, civil…

  8. Lessons from Katrina

    ERIC Educational Resources Information Center

    Albrecht, Kay

    2005-01-01

    In this article, the author relates the lessons she learned from Hurricane Katrina. During the first few days after the hurricane, it took 2,500 volunteers per hour around the clock to do what needed to be done. That included medical volunteers; crisis counselors and mental health professionals; and volunteers to distribute water and snacks, serve…

  9. The Katrina Kids

    ERIC Educational Resources Information Center

    Meyer, B. L.

    2007-01-01

    As the second anniversary of Hurricane Katrina rolls in, thoughts return again to those bleak days, watching people cling to their rooftops, waiting for a hand. Marking milestones, celebrating small victories, and sharing stories when things work out is a big part of life for those who work to support and connect families of children with…

  10. Wind Field Predictions for the Columbia Gorge and the Goodnoe Hills Wind Turbine Site.

    SciTech Connect

    Veenhuizen, Scott D.; Lin, Jung-Tai.

    1980-08-01

    Numerical estimates of the long term seasonal mean wind speeds, wind directions, and available wind power density were conducted for comparison with the results of field wind measurements obtained by the Bonneville Power Administration for the Columbia Gorge region along the Oregon-Washngton border. The authors had previously used the numerical method of estimating wind flows in complex terrain to identify high wind energy areas within the Olympic Peninsula and Northern Cascade regions of the State of Washington. The numerical technique was used as a generalized wind prospecting tool to provide the link between regional assessments and on-site biological or geomorphological indicators of mean wind speeds and available wind energy. The wind flow model used is a two dimensional model based upon simplified hydrodynamical equations describing the fluid and thermodynamic motion of the atmosphere.

  11. "Keeping it Real -High School Science Curriculum"- Hurricane Katrina and BP Oil Spill inspire creative curriculum by Dave Jungblut, Oakcrest High School Science Teacher, Mays Landing, NJ

    NASA Astrophysics Data System (ADS)

    Jungblut, D.

    2011-12-01

    After Hurricane Katrina devastated Gulf Coast homes in 2005, Oakcrest High School science teacher and geologist, Dave Jungblut, traveled from Gulfport to Ocean Springs, Mississippi and conducted research to determine whether property damage was caused by wind or water. Jungblut wrote several studies, " Katrina Straight- Line Wind Field Study", "Applying Research to Practical Use for Hurricane Katrina Homeowners", and "Hurricane Katrina Wind Study" proving wind damage. Jungblut's research, done pro bono, helped thousands of homeowner's in the Mississippi area be reimbursed by insurance companies for wind damage caused by Hurricane Katrina http://www.hurricanekatrinastudy.com/ Jungblut incorporated his extensive data, in a high school curriculum that is now part of the science program he teaches each year. In January 2010, Jungblut presented "Hurricane Forensics" curriculum at the Rutgers Center for Mathematics, Science and Computer January 2009 Workshop http://www.dimacs.rutgers.edu/wst/. Through labs and creative hands-on activities, Jungblut challenged his students to analyze the photographic evidence, and data he collected, for themselves. Jungblut taught his students how to use geologic and forensic inquiry techniques to discover the difference between straight-line winds from microburst activity. The students applied the concept of the Geological Principle of Relative Dating, to determine the sequence of events that happened during Hurricane Katrina. They built model structures, which were subjected to wind and water forces to better understand the effects of these phenomena, Finally, the students evaluated local and worldwide environmental issues, such as land use risks and benefits, in the face of global warming, In the spring of 2010 when the BP Oil Spill occurred, Jungblut realized, another opportunity to bring real world issues into the classroom. After exploring scientific concepts relating to this environmental crisis, Jungblut challenged his students to

  12. Comparison of field and wind-tunnel Darrieus wind-turbine data

    NASA Astrophysics Data System (ADS)

    Sheldahl, R. E.

    1981-08-01

    A 2-m-diam Darrieus vertical axis wind turbine with NACA-0012 airfoil blades was tested in the field and in a 4.6 x 6.1-m low speed wind tunnel for a direct comparison. Comparisons were made with field data of equivalent chord Reynolds number, and at equivalent rotational field. Maximum values of the power coefficients compared favorably, and an examination of performance coefficients showed complete agreement between wind tunnel and field data. Due to excellent agreement in the first two comparisons, no further field testing was done, and the accuracy of the wind-tunnel test data was believed verified.

  13. REGIONAL-SCALE WIND FIELD CLASSIFICATION EMPLOYING CLUSTER ANALYSIS

    SciTech Connect

    Glascoe, L G; Glaser, R E; Chin, H S; Loosmore, G A

    2004-06-17

    The classification of time-varying multivariate regional-scale wind fields at a specific location can assist event planning as well as consequence and risk analysis. Further, wind field classification involves data transformation and inference techniques that effectively characterize stochastic wind field variation. Such a classification scheme is potentially useful for addressing overall atmospheric transport uncertainty and meteorological parameter sensitivity issues. Different methods to classify wind fields over a location include the principal component analysis of wind data (e.g., Hardy and Walton, 1978) and the use of cluster analysis for wind data (e.g., Green et al., 1992; Kaufmann and Weber, 1996). The goal of this study is to use a clustering method to classify the winds of a gridded data set, i.e, from meteorological simulations generated by a forecast model.

  14. Mod-2 wind turbine field operations experiment

    NASA Technical Reports Server (NTRS)

    Gordon, L. H.

    1985-01-01

    The three-machine, 7.5 MW Goodnoe Hills located near Goldendale, Washington and is now in a research/experimental operations phase that offers a unique opportunity to study the effects of single and multiple wind turbines interacting with each other, the power grid; and the environment. Following a brief description of the turbine and project history, this paper addresses major problem areas and research and development test results. Field operations, both routine and nonroutine, are discussed. Routine operation to date has produced over 13,379,000 KWh of electrical energy during 11,064 hr of rotation. Nonroutine operation includes suspended activities caused by a crack in the low speed shaft that necessitated a redesign and reinstallation of this assembly on all three turbines. With the world's largest cluster back in full operation, two of the turbines will be operated over the next years to determine their value as energy producer. The third unit will be used primarily for conducting research tests requiring configuration changes to better understand the wind turbine technology. Technical areas summarized pertain to system performance and enhancements. Specific research tests relating to acoustics, TV interference, and wake effects conclude the paper.

  15. Simulation of the surface wind field and wind waves over the Oman Sea

    NASA Astrophysics Data System (ADS)

    Hamzeloo, Sima; Hadi Moeini, Mohammad; Jandaghi Alaee, Majid

    2016-04-01

    Surface wind field is one of the most important factors in the generation of the marine hydrodynamic phenomena such as wind waves that highly affected by the surface winds. Therefore, accessibility to the correct wind field is of great importance for accurate prediction and simulation of the hydrodynamic variables. Nowadays numerical mesoscale weather prediction models are widely applied as powerful tools to simulate wind and other atmospheric variables with predefined temporal and spatial resolution in desired areas. Despite appropriate results of the numerical models in many regions, there are still some complications in the simulation of the surface wind field in areas with complex orography since the surface wind field is highly affected by the local topography, land-sea discontinuity, temperature gradient etc. Nowadays, with the development of high-speed processors the third generation spectral models are generally used for simulation of wind waves. Wind data are the main input parameters of the numerical spectral wave model. Therefore, the quality of the input wind data can be assessed by comparison of the wave model outputs with measured values. The main goal of the current study is to simulate surface wind field over the Oman Sea using WRF modeling system. To verify the model results, the simulated wind speeds were compared with synoptic and buoy measurements and satellite observations. Wind-wave parameters simulated by the spectral model were also compared with wave measurements to verify simulated surface wind field as the input of the wave model. The Comparison simulated wind speed and directions in coastal synoptic stations and QuikSCAT satellite shows sufficient results for both offshore and coastal areas.

  16. Wind loads on flat plate photovoltaic array fields

    NASA Technical Reports Server (NTRS)

    Miller, R. D.; Zimmerman, D. K.

    1981-01-01

    The results of an experimental analysis (boundary layer wind tunnel test) of the aerodynamic forces resulting from winds acting on flat plate photovoltaic arrays are presented. Local pressure coefficient distributions and normal force coefficients on the arrays are shown and compared to theoretical results. Parameters that were varied when determining the aerodynamic forces included tilt angle, array separation, ground clearance, protective wind barriers, and the effect of the wind velocity profile. Recommended design wind forces and pressures are presented, which envelop the test results for winds perpendicular to the array's longitudinal axis. This wind direction produces the maximum wind loads on the arrays except at the array edge where oblique winds produce larger edge pressure loads. The arrays located at the outer boundary of an array field have a protective influence on the interior arrays of the field. A significant decrease of the array wind loads were recorded in the wind tunnel test on array panels located behind a fence and/or interior to the array field compared to the arrays on the boundary and unprotected from the wind. The magnitude of this decrease was the same whether caused by a fence or upwind arrays.

  17. A field study of wind over a simulated block building

    NASA Technical Reports Server (NTRS)

    Frost, W.; Shahabi, A. M.

    1977-01-01

    A full-scale field study of the wind over a simulated two-dimensional building is reported. The study develops an experiment to investigate the structure and magnitude of the wind fields. A description of the experimental arrangement, the type and expected accuracy of the data, and the range of the data are given. The data are expected to provide a fundamental understanding of mean wind and turbulence structure of the wind field around the bluff body. Preliminary analysis of the data demonstrates the reliability and completeness of the data in this regard.

  18. Diagnostic Mass-Consistent Wind Field Monte Carlo Dispersion Model

    1991-01-01

    MATHEW generates a diagnostic mass-consistent, three-dimensional wind field based on point measurements of wind speed and direction. It accounts for changes in topography within its calculational domain. The modeled wind field is used by the Langrangian ADPIC dispersion model. This code is designed to predict the atmospheric boundary layer transport and diffusion of neutrally bouyant, non-reactive species as well as first-order chemical reactions and radioactive decay (including daughter products).

  19. Cloud Spirals and Outflow in Tropical Storm Katrina

    NASA Technical Reports Server (NTRS)

    2005-01-01

    On Tuesday, August 30, 2005, NASA's Multi-angle Imaging SpectroRadiometer retrieved cloud-top heights and cloud-tracked wind velocities for Tropical Storm Katrina, as the center of the storm was situated over the Tennessee valley. At this time Katrina was weakening and no longer classified as a hurricane, and would soon become an extratropical depression. Measurements such as these can help atmospheric scientists compare results of computer-generated hurricane simulations with observed conditions, ultimately allowing them to better represent and understand physical processes occurring in hurricanes.

    Because air currents are influenced by the Coriolis force (caused by the rotation of the Earth), Northern Hemisphere hurricanes are characterized by an inward counterclockwise (cyclonic) rotation towards the center. It is less widely known that, at high altitudes, outward-spreading bands of cloud rotate in a clockwise (anticyclonic) direction. The image on the left shows the retrieved cloud-tracked winds as red arrows superimposed across the natural color view from MISR's nadir (vertical-viewing) camera. Both the counter-clockwise motion for the lower-level storm clouds and the clockwise motion for the upper clouds are apparent in these images. The speeds for the clockwise upper level winds have typical values between 40 and 45 m/s (144-162 km/hr). The low level counterclockwise winds have typical values between 7 and 24 m/s (25-86 km/hr), weakening with distance from the storm center. The image on the right displays the cloud-top height retrievals. Areas where cloud heights could not be retrieved are shown in dark gray. Both the wind velocity vectors and the cloud-top height field were produced by automated computer recognition of displacements in spatial features within successive MISR images acquired at different view angles and at slightly different times.

    The Multi-angle Imaging SpectroRadiometer observes the daylit Earth continuously, viewing the

  20. Katrina's Progress with Learning Mathematics

    ERIC Educational Resources Information Center

    McConnochie, Jan; Sneath, Greg

    2007-01-01

    Katrina is 10 years old and has Down syndrome. She is making good progress with learning numbers and mathematics. We describe how Katrina has learned number concepts and arithmetic skills over several years. We highlight the influence of early learning habits, visual supports, motivation and practice, and the uses made of different number…

  1. Interplanetary stream magnetism: Kinematic effects. [solar magnetic fields and wind

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; Barouch, E.

    1974-01-01

    The particle density, and the magnetic field intensity and direction are calculated in corotating streams of the solar wind, assuming that the solar wind velocity is constant and radial and that its azimuthal variations are not two rapid. The effects of the radial velocity profile in corotating streams on the magnetic fields were examined using kinematic approximation and a variety of field configurations on the inner boundary. Kinematic and dynamic effects are discussed.

  2. Probabilistic Motion Planning of Balloons in Strong, Uncertain Wind Fields

    NASA Technical Reports Server (NTRS)

    Wolf, Michael T.; Blackmore, Lars; Kuwata, Yoshiaki; Fathpour, Nanaz; Elfes, Alberto; Newman, Claire

    2010-01-01

    This paper introduces a new algorithm for probabilistic motion planning in arbitrary, uncertain vector fields, with emphasis on high-level planning for Montgolfiere balloons in the atmosphere of Titan. The goal of the algorithm is to determine what altitude--and what horizontal actuation, if any is available on the vehicle--to use to reach a goal location in the fastest expected time. The winds can vary greatly at different altitudes and are strong relative to any feasible horizontal actuation, so the incorporation of the winds is critical for guidance plans. This paper focuses on how to integrate the uncertainty of the wind field into the wind model and how to reach a goal location through the uncertain wind field, using a Markov decision process (MDP). The resulting probabilistic solutions enable more robust guidance plans and more thorough analysis of potential paths than existing methods.

  3. Brushless exciters using a high temperature superconducting field winding

    SciTech Connect

    Garces, Luis Jose; Delmerico, Robert William; Jansen, Patrick Lee; Parslow, John Harold; Sanderson, Harold Copeland; Sinha, Gautam

    2008-03-18

    A brushless exciter for a synchronous generator or motor generally includes a stator and a rotor rotatably disposed within the stator. The rotor has a field winding and a voltage rectifying bridge circuit connected in parallel to the field winding. A plurality of firing circuits are connected the voltage rectifying bridge circuit. The firing circuit is configured to fire a signal at an angle of less than 90.degree. or at an angle greater than 90.degree.. The voltage rectifying bridge circuit rectifies the AC voltage to excite or de-excite the field winding.

  4. Structure of magnetic field in the solar wind

    NASA Technical Reports Server (NTRS)

    Chertkov, A. D.

    1995-01-01

    This work is concerned with empirical data on magnetic field in the solar wind in frame of a concept of dissipative solar wind, developed in papers (Solar Wind 7 Conf., Pergamon Press, 1992, 165 and 1992 STEP/5th COSPAR Coll. Pergamon Press, 1994, 117; 235; 803). Interplanetary magnetic fields should be classified with respect to their origin. It is very important for all the theoretical problems from the necessity to specify correctly boundary and initial conditions: the magnetic field must be sewed with its source. One should select the field, connected directly with the Sun (stretched out from it), and the field of moving electric currents. It occured central in discussion about the velocity of Alfven waves, probably warming up the solar wind, relative to the Sun, the magnetic field and solar wind plasma. The selection problem corresponds to an inverse problem and obviously has no single solution. The dissipative model of the solar wind introduce the slipping and leakage of plasma relative to magnetic field. There are no 'interplanetary current sheets' in it. But temporal fluctuations from the filamentation of electric currents play the key role. As a whole, the new concept requires the re-interpretation of main objects in the interplanetary magnetic field.

  5. Shelf sediment transport during hurricanes Katrina and Rita

    NASA Astrophysics Data System (ADS)

    Xu, Kehui; Mickey, Rangley C.; Chen, Qin; Harris, Courtney K.; Hetland, Robert D.; Hu, Kelin; Wang, Jiaze

    2016-05-01

    Hurricanes can greatly modify the sedimentary record, but our coastal scientific community has rather limited capability to predict hurricane-induced sediment deposition. A three-dimensional sediment transport model was developed in the Regional Ocean Modeling System (ROMS) to study seabed erosion and deposition on the Louisiana shelf in response to Hurricanes Katrina and Rita in the year 2005. Sensitivity tests were performed on both erosional and depositional processes for a wide range of erosional rates and settling velocities, and uncertainty analysis was done on critical shear stresses using the polynomial chaos approximation method. A total of 22 model runs were performed in sensitivity and uncertainty tests. Estimated maximum erosional depths were sensitive to the inputs, but horizontal erosional patterns seemed to be controlled mainly by hurricane tracks, wave-current combined shear stresses, seabed grain sizes, and shelf bathymetry. During the passage of two hurricanes, local resuspension and deposition dominated the sediment transport mechanisms. Hurricane Katrina followed a shelf-perpendicular track before making landfall and its energy dissipated rapidly within about 48 h along the eastern Louisiana coast. In contrast, Hurricane Rita followed a more shelf-oblique track and disturbed the seabed extensively during its 84-h passage from the Alabama-Mississippi border to the Louisiana-Texas border. Conditions to either side of Hurricane Rita's storm track differed substantially, with the region to the east having stronger winds, taller waves and thus deeper erosions. This study indicated that major hurricanes can disturb the shelf at centimeter to meter levels. Each of these two hurricanes suspended seabed sediment mass that far exceeded the annual sediment inputs from the Mississippi and Atchafalaya Rivers, but the net transport from shelves to estuaries is yet to be determined. Future studies should focus on the modeling of sediment exchange between

  6. The near-surface wind field over the Antarctic continent

    NASA Astrophysics Data System (ADS)

    van Lipzig, N. P. M.; Turner, J.; Colwell, S. R.; van den Broeke, M. R.

    2004-12-01

    A 14 year integration with a regional atmospheric model has been used to determine the near-surface climatological wind field over the Antarctic ice sheet at a horizontal grid spacing of 55 km. Previous maps of the near-surface wind field were generally based on models ignoring the large-scale pressure-gradient forcing term in the momentum equation. Presently, state-of-the-art atmospheric models include all pressure-gradient forcing terms. Evaluation of our model output against in situ data shows that the model is able to represent realistically the observed increase in wind speed going from the interior to the coast, as well as the observed wind direction at South Pole and Dumont d'Urville and the bimodal wind distribution at Halley.

  7. Gridded wind fields derived from scatterometer, altimeter, and SSM/I wind measurements

    SciTech Connect

    Bentamy, A.; Gohin, F.; Queffeulou, P.; Quilfen, Y.; Katsaros, K.

    1994-12-31

    The sea surface wind is an important variable in the study of the interactions between ocean and atmosphere. Wind over the ocean modulates air-sea fluxes of heat, moisture, gases and particulates, thus regulating the crucial coupling between atmosphere and ocean that establishes and maintains global and regional climates. In this paper, the authors are concerned with three instruments which provide an estimate of the wind speed over the sea surface at different scales. The scatterometer, which is a dedicated wind instrument, and the altimeter are mounted on the ERS-1 satellite. The third instrument is the Special Sensor Microwave/Imager (SSM/I) which is deployed on board the Defense Meteorological Satellites Program (DMSP) satellites F10 and F11. The main aim of the use of the derived wind speed from these three instruments is to compute an accurate regularly wind field over an ocean region with high space and time resolution which will be used to force an ocean circulation model. Furthermore, the combination of passive and active microwave satellite instruments yields new insights into the study of some atmospheric systems as the evolution of fronts and tropical cyclones. The authors will present the quality of the altimeter and SSM/I wind speed estimates by comparison with wind speeds derived from the ERS-1 scatterometer. They will discuss the results of the intercomparison between the winds inferred from the three sensors along with colocated buoy wind measurements.

  8. Scaling up from field to region for wind erosion prediction using a field-scale wind erosion model and GIS

    USGS Publications Warehouse

    Zobeck, T.M.; Parker, N.C.; Haskell, S.; Guoding, K.

    2000-01-01

    Factors that affect wind erosion such as surface vegetative and other cover, soil properties and surface roughness usually change spatially and temporally at the field-scale to produce important field-scale variations in wind erosion. Accurate estimation of wind erosion when scaling up from fields to regions, while maintaining meaningful field-scale process details, remains a challenge. The objectives of this study were to evaluate the feasibility of using a field-scale wind erosion model with a geographic information system (GIS) to scale up to regional levels and to quantify the differences in wind erosion estimates produced by different scales of soil mapping used as a data layer in the model. A GIS was used in combination with the revised wind erosion equation (RWEQ), a field-scale wind erosion model, to estimate wind erosion for two 50 km2 areas. Landsat Thematic Mapper satellite imagery from 1993 with 30 m resolution was used as a base map. The GIS database layers included land use, soils, and other features such as roads. The major land use was agricultural fields. Data on 1993 crop management for selected fields of each crop type were collected from local government agency offices and used to 'train' the computer to classify land areas by crop and type of irrigation (agroecosystem) using commercially available software. The land area of the agricultural land uses was overestimated by 6.5% in one region (Lubbock County, TX, USA) and underestimated by about 21% in an adjacent region (Terry County, TX, USA). The total estimated wind erosion potential for Terry County was about four times that estimated for adjacent Lubbock County. The difference in potential erosion among the counties was attributed to regional differences in surface soil texture. In a comparison of different soil map scales in Terry County, the generalised soil map had over 20% more of the land area and over 15% greater erosion potential in loamy sand soils than did the detailed soil map. As

  9. Simulation of wind performance in tropical cyclone for China's future dual-frequency wind field radar

    NASA Astrophysics Data System (ADS)

    Dou, Fangli; Yin, Honggang; Gu, Songyan

    2014-11-01

    Ocean surface wind vectors (OVW) from scatterometers have been proved to be of great benefit to marine weather analysis and numerical model prediction. Conventional single-frequency scatterometers are capable to measure substantially accurate wind fields in clear atmospheric conditions, whereas winds obtained in marine extreme weather conditions are not so satisfying due to the high wind speed saturation effect and the rain perturbation. Therefore, a dualfrequency wind field measuring radar (WIFIR) to be onboard FengYun-3E is being predesigned to obtain relatively accurate wind fields in all weather conditions, which will compensate for the single-frequency shortcomings. The purpose of this study was to investigate the potential ability of WIFIR to measure OVW in tropical cyclones. A high-fidelity forward model was developed to simulate the sea surface normalize radar cross sections (NRCS) measured by WIFIR. The wind and rain rate fields used to drive the model are generated by UWNMS cloud model for Hurricane Ivan in 2004. High-wind GMFs and a theoretical rain model, which includes attenuation and volume scattering effect, have been utilized to describe the forward model. Based on the simulation results, the impact of rain on radar measurements and a dual-frequency retrieval algorithm were studied. The dual-frequency method was shown to have the ability to obtain information of rain rates up to 30mm/hr, and acquire more accurate wind vectors than single-frequency measurements. This method will be more effective to improve wind retrieval accuracy in tropical cyclones with the synchronous observation of microwave humidity sounder (MWHS) aboard FY-3 satellite.

  10. Magnetic fields of Mars and Venus - Solar wind interactions

    NASA Technical Reports Server (NTRS)

    Ness, N. F.

    1974-01-01

    Recent USSR studies of the magnetic field and solar wind flow in the vicinity of Mars and Venus confirm earlier U.S. reports of a bow shock wave developed as the solar wind interacts with these planets. Mars 2 and 3 magnetometer experiments report the existence of an intrinsic planetary magnetic field, sufficiently strong to form a magnetopause, deflecting the solar wind around the planet and its ionosphere. This is in contrast to the case for Venus, where it is assumed to be the ionosphere and processes therein which are responsible for the solar wind deflection. An empirical relationship appears to exist between planetary dipole magnetic moments and their angular momentum for the Moon, Mars, Venus, Earth, and Jupiter. Implications for the magnetic fields of Mercury and Saturn are discussed.

  11. Identification of wind fields for wave modeling near Qatar

    NASA Astrophysics Data System (ADS)

    Nayak, Sashikant; Balan Sobhana, Sandeepan; Panchang, Vijay

    2016-04-01

    Due to the development of coastal and offshore infrastructure in and around the Arabian Gulf, a large semi-enclosed sea, knowledge of met-ocean factors like prevailing wind systems, wind generated waves, and currents etc. are of great importance. Primarily it is important to identify the wind fields that are used as forcing functions for wave and circulation models for hindcasting and forecasting purposes. The present study investigates the effects of using two sources of wind-fields on the modeling of wind-waves in the Arabian Gulf, in particular near the coastal regions of Qatar. Two wind sources are considered here, those obtained from ECMWF and those generated by us using the WRF model. The wave model SWAN was first forced with the 6 hourly ERA Interim daily winds (from ECMWF) having spatial resolution of 0.125°. For the second option, wind fields were generated by us using the mesoscale wind model (WRF) with a high spatial resolution (0.1°) at every 30 minute intervals. The simulations were carried out for a period of two months (7th October-7th December, 2015) during which measurements were available from two moored buoys (deployed and operated by the Qatar Meteorological Department), one in the north of Qatar ("Qatar North", in water depth of 58.7 m) and other in the south ("Shiraouh Island", in water depth of 16.64 m). This period included a high-sea event on 11-12th of October, recorded by the two buoys where the significant wave heights (Hs) reached as high as 2.9 m (i.e. max wave height H ~ 5.22 m) and 1.9 (max wave height H ~ 3.4 m) respectively. Model results were compared with the data for this period. The scatter index (SI) of the Hs simulated using the WRF wind fields and the observed Hs was found to be about 30% and 32% for the two buoys (total period). The observed Hs were generally reproduced but there was consistent underestimation. (Maximum 27% for the high-sea event). For the Hs obtained with ERA interim wind fields, the underestimation was

  12. Wind tunnel and field calibration of six aeolian dust samplers

    NASA Astrophysics Data System (ADS)

    Goossens, Dirk; Offer, Zvi Y.

    The efficiency of six aeolian dust samplers was tested via wind tunnel experiments and field measurements. In the wind tunnel, four samplers designed to measure the horizontal dust flux and one sampler designed to measure the vertical dust flux (in the downward direction, i.e., deposition) were calibrated against an isokinetic reference sampler. The horizontal dust flux samplers were: the big spring number eight sampler (BSNE), the modified Wilson and Cooke sampler (MWAC), the suspended sediment trap (SUSTRA), and the wedge dust flux gauge (WDFG). Vertical deposition flux was measured using a marble dust collector (MDCO). A modified Sartorius SM 16711 dust sampler with adjustable flow rate (SARTORIUS) was used as isokinetic reference sampler. In the field experiments, the WDFG was replaced by a Sierra ultra high volume dust sampler (SIERRA). Wind tunnel calibrations were carried out at five wind velocities ranging from 1 to 5 m s -1. Field calibrations were conducted during seven periods of two weeks each. The most efficient samplers are the MWAC and the SIERRA, followed by the BSNE and the SUSTRA. The WDFG is more effective than the BSNE at velocities below 3 m s -1, but its efficiency drops quickly at higher wind speeds. The most recommendable sampler for field measurements is the BSNE, because its efficiency varies only very slightly with wind speed. In the absence of horizontal flux samplers, the MDCO collector can be used as an alternative to assess horizontal dust flux and airborne dust concentration provided the appropriate calibrations are made.

  13. Satellite Studies of Ionospheric Electric Fields and Neutral Winds

    NASA Technical Reports Server (NTRS)

    Fejer, Bela G.

    2002-01-01

    We have studied mid- and low-latitude electrodynamic and neutral thermospheric dynamic processes using measurements on board the AE-E, DE-2, and UARS (Upper Atmosphere Research Satellite) satellites, and global convection and general circulation models. These studies have determined the morphology of the equatorial zonal electric fields, the response of equatorial plasma irregularities to magnetospheric disturbances, and the time dependent response of the mid- and low latitude electric fields to magnetospheric disturbances. We have also used extensive F region zonal and meridional wind data obtained by Wind Imaging Interferometer (WINDII) instrument on board the UARS to study the latitudinal dependence of daytime disturbance winds during magnetically disturbed periods and the general characteristics of the global thermospheric disturbance wind system during geomagnetically active periods. This project has supported the PhD thesis research of John Emmert.

  14. Discussion - Winds and magnetic fields of active OB stars

    NASA Astrophysics Data System (ADS)

    Bouret, Jean-Claude; Cidale, Lydia

    2011-07-01

    The discussion on winds and magnetic fields of active OB stars was carried out by S. Owoki, G. Wade, M. Cantiello, O. Kochukhov, M. Smith, C. Neiner, T. Rivinius, H. Henrichs and R. Townsend. The topics were the ability to detect small and large scale magnetic fields in massive stars and the need to consider limits on photometric variability of the star surface brightness.

  15. Extratropical transitioning in the RMS Japan typhoon wind field model

    NASA Astrophysics Data System (ADS)

    Loridan, Thomas; Scherer, Emilie; Khare, Shree

    2013-04-01

    Given its meridional extent and location within the Pacific basin, Japan is regularly impacted by strong winds from cyclones at different stages of their lifecycle. To quantify the associated risk of damage to properties, catastrophe models such as the ones developed by RMS aim to simulate wind fields from thousands of stochastic storms that extrapolate historical events. In a recent study using 25 years of reanalysis data, Kitabatake (2011) estimated that 40 % of all Pacific tropical cyclones completed their transition as an extra tropical system. From a cat modelling point of view it is the increase in wind field asymmetry observed during these transitioning episodes that is critical, with examples like typhoon Tokage in 2004 showing the potential for damaging gusts on both sides of the storm track. In this context a compromise has to be found between the need for complex numerical models able to simulate wind field variability around the cyclone during its entire evolution, and obvious running time constrains. The RMS wind field model is based on an optimized version of the Willoughby parametric profile (Willoughby et al., 2006) which requires calibration against targets representative of cyclone wind fields throughout their lifecycle. We here present the different sources of data involved in the development of this model. This includes (1) satellite products to characterize wind fields from fully tropical storms, (2) high resolution simulations of key transitioning events using the WRF mesoscale model to complement the database at other stages (i.e. for transitioning and fully extra tropical wind fields), and (3) reanalysis data which can be used with Hart (2003)'s cyclone phase space methodology to provide an estimate of the mean duration of transitioning episodes in the Pacific. Kitabatake, N., 2011: Climatology of extratropical transition of tropical cyclones in the Western North Pacific defined by using cyclone phase space. J. Meteor. Soc. Japan, 89, 309

  16. Verification of wind fields by means of rain cell tracking

    NASA Astrophysics Data System (ADS)

    Herbort, F.

    2009-09-01

    VERIFICATION OF WIND FIELDS BY MEANS OF RAIN CELL TRACKING Herbort, F., Knigge, C. and Etling, D, Institute of Meteorology and Climatology, Leibniz University Hannover,Germany herbort@muk.uni-hannover.de The regional weather forecast model COSMO-DE of the German weather service is run at a spatial resolution of 2.8 km. This results in rather detailed simulations of meteorological fields like pressure, temperature and wind. In contrast, for verification of those NWP products outside the atmospheric surface layer, only a few radiosonde stations can provide the necessary observations. In order to improve the spatial and temporal resolution of observed wind fields we propose a new method based on the motion of rain cells as observed by the German rain radar network. The radar product consist of the radar reflectivity over Germany caused by hydrometeors with a spatial resolution of about 1 km and a temporal resolution of 5 minutes. The tracking of localised radar echoes caused by post frontal showers has been used for statistical analysis of rain showers in earlier work at our institute (Weusthoff and Hauf,2008). The fields of radar reflectivity are analysed in our work by the so-called PIV (Particle Image Velocimetry) method as used in experimental fluid mechanics for obtaining velocity fields of flow phenomena. Instead of solid particles as used as tracking objects in laboratory flows we use the localised radar reflectivities caused by the rain showers as tracer particles for the PIV method. The PIV algorithm provides two dimensional wind fields in the area of Germany with a few kilometres spatial resolution. The observed wind fields are compared to the wind fields obtained by the COSMO-DE model at several vertical levels in the lowest 4 kilometres of the atmosphere. By this way we could not only obtain some estimates for the skill of the wind field forecasts of the model but also could provide information on the most suitable model level for wind forecast

  17. Coronal Magnetic Field Topology and Source of Fast Solar Wind

    NASA Technical Reports Server (NTRS)

    Guhathakurta, M.; Sittler, E.; Fisher, R.; McComas, D.; Thompson, B.

    1999-01-01

    We have developed a steady state, 2D semi-empirical MHD model of the solar corona and the solar wind with many surprising results. This model for the first time shows, that the boundary between the fast and the slow solar wind as observed by Ulysses beyond 1 AU, is established in the low corona. The fastest wind observed by Ulysses (680-780 km/s) originates from the polar coronal holes at 70 -90 deg. latitude at the Sun. Rapidly diverging magnetic field geometry accounts for the fast wind reaching down to a latitude of +/- 30 deg. at the orbit of Earth. The gradual increase in the fast wind observed by Ulysses, with latitude, can be explained by an increasing field strength towards the poles, which causes Alfven wave energy flux to increase towards the poles. Empirically, there is a direct relationship between this gradual increase in wind speed and the expansion factor, f, computed at r greater than 20%. This relationship is inverse if f is computed very close to the Sun.

  18. Construction of solar-wind-like magnetic fields.

    PubMed

    Roberts, D Aaron

    2012-12-01

    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.

  19. Construction of Solar-Wind-Like Magnetic Fields

    NASA Technical Reports Server (NTRS)

    Roberts, Dana Aaron

    2012-01-01

    Fluctuations in the solar wind fields tend to not only have velocities and magnetic fields correlated in the sense consistent with Alfven waves traveling from the Sun, but they also have the magnitude of the magnetic field remarkably constant despite their being broadband. This paper 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.

  20. Wind effects in solar fields with various collector designs

    NASA Astrophysics Data System (ADS)

    Paetzold, Joachim; Cochard, Steve; Fletcher, David F.; Vassallo, Anthony

    2016-05-01

    Parabolic trough power plants are often located in areas that are subjected to high wind speeds, as an open terrain without any obstructions is beneficial for the plant performance. The wind impacts both the structural requirements and the performance of the plant. The aerodynamic loads from the wind impose strong requirements on the support structure of the reflectors, and they also impact the tracking accuracy. On a thermal level the airflow around the glass envelope of the receiver tube cools its outer surface through forced convection, thereby contributing to the heat loss. Based on previous studies at the level of an individual row of collectors, this study analyses the wind effects in a full-scale solar field of different continuous and staggered trough designs. The airflow around several rows of parabolic trough collectors (PTC) is simulated at full scale in steady state simulations in an atmospheric boundary layer flow using the commercial computational fluid dynamics software ANSYSO® CFX 15.0. The effect of the wake of a collector row on the following collectors is analysed, and the aerodynamic loads are compared between the different geometries. The outermost collectors of a solar field experience the highest wind forces, as the rows in the interior of the solar field are protected from high wind speeds. While the aerodynamic forces in the interior of the solar field are almost independent of the collector shape, the deeper troughs (with large rim angles) tested in this study show a lower heat loss due to forced convection on the outer surface of the receiver tube than the shallower ones (with small rim angles) in most of the solar field.

  1. Hurricane Season 2005: Katrina

    NASA Technical Reports Server (NTRS)

    2005-01-01

    Seventeen days after Hurricane Katrina flooded New Orleans, much of the city is still under water. In this pair of images from the Advanced Spaceborne Thermal Emission and Reflection Radiometer on NASA's Terra satellite, the affected areas can clearly be seen. The top image mosaic was acquired in April and September 2000, and the bottom image was acquired September 13, 2005. The flooded parts of the city appear dark blue, such as the golf course in the northeast corner, where there is standing water. Areas that have dried out appear light blue gray, such as the city park in the left middle. On the left side of the image, the failed 17th street canal marks a sharp boundary between flooded city to the east, and dry land to the west.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

    Size: 10.4 by 7.1 kilometers Location: 30 degrees North latitude, 90.1 degrees West longitude Orientation: North at top Image Data: ASTER bands 1, 2, and 3 Original Data Resolution: 15 meters (49.2 feet) Dates Acquired: September 13, 2005

  2. Hurricane Katrina at Tulane.

    NASA Astrophysics Data System (ADS)

    McGuire, Jim

    2008-03-01

    After hurricane Katrina struck New Orleans on August 29, 2005, Tulane University closed for the fall semester. Buildings on campus were closed and armed guards were hired to protect the campus. Faculty members were not allowed access to their offices and laboratories, except for exceptional cases when a Dean went with them. Many faculty members took their research groups to other universities accepting much welcomed invitations from colleagues. Undergraduates went to other colleges and universities, which accepted the without cost and a promise not to recruit them. The university email system went down for months. Collecting information on the welfare of faculty and students was difficult. The university was run from Houston by a small handful of senior administrators. Setting up the schedule of classes for the spring 2006 semester was done without records. Most faculty returned to New Orleans after several weeks. 80% of the city was flooded. Small trailers were provided. Some lived in the FEMA trailers for two years or more. When Tulane reopened, a wide reaching Renewal Plan, worked out by the upper administration, was implemented. A new emergency preparedness plan was also developed and put in place.

  3. Model-based estimation of wind fields over the ocean from wind scatterometer measurements. I - Development of the wind field model. II - Model parameter estimation

    NASA Technical Reports Server (NTRS)

    Long, David G.; Mendel, Jerry M.

    1990-01-01

    Techniques for the determination of near-surface mesoscale ocean wind fields on the basis of satellite scatterometer data are developed and demonstrated. The derivation of normal-boundary and parameterized-boundary-condition (PBC) wind-field models is outlined, and results from a simulation performed to estimate the model errors are presented in tables. It is shown that the PBC model provides accurate results while minimizing the number of unknowns. After a review of the principles of scatterometry and an analysis of scatterometer measurement noise, an objective function for the measurement parameters is developed and optimized on the basis of gradient search with initial values computed from pointwise wind estimates. The model is then applied to data from a simulation of the NASA Scatterometer (Li et al., 1984), and the results are presented in extensive graphs. The feasibility of model-based wind-field estimation and the appropriateness of the PBC model are demonstrated.

  4. Efficient Low-Speed Flight in a Wind Field

    NASA Technical Reports Server (NTRS)

    Feldman, Michael A.

    1996-01-01

    A new software tool was needed for flight planning of a high altitude, low speed unmanned aerial vehicle which would be flying in winds close to the actual airspeed of the vehicle. An energy modeled NLP (non-linear programming) formulation was used to obtain results for a variety of missions and wind profiles. The energy constraint derived included terms due to the wind field and the performance index was a weighted combination of the amount of fuel used and the final time. With no emphasis on time and with no winds the vehicle was found to fly at maximum lift to drag velocity, V(sub md). When flying in tail winds the velocity was less than V(sub md), while flying in head winds the velocity was higher than V(sub md). A family of solutions was found with varying times of flight and varying fuel amounts consumed which will aid the operator in choosing a flight plan depending on a desired landing time. At certain parts of the flight, the turning terms in the energy constraint equation were found to be significant. An analysis of a simpler vertical plane cruise optimal control problem was used to explain some of the characteristics of the vertical plane NLP results.

  5. Synoptic scale wind field properties from the SEASAT SASS

    NASA Technical Reports Server (NTRS)

    Pierson, W. J., Jr.; Sylvester, W. B.; Salfi, R. E.

    1984-01-01

    Dealiased SEASAT SEASAT A Scatterometer System SASS vector winds obtained during the Gulf Of Alaska SEASAT Experiment GOASEX program are processed to obtain superobservations centered on a one degree by one degree grid. The grid. The results provide values for the combined effects of mesoscale variability and communication noise on the individual SASS winds. These superobservations winds are then processed further to obtain estimates of synoptic scale vector winds stress fields, the horizontal divergence of the wind, the curl of the wind stress and the vertical velocity at 200 m above the sea surface, each with appropriate standard deviations of the estimates for each grid point value. They also explain the concentration of water vapor, liquid water and precipitation found by means of the SMMR Scanning Multichannel Microwave Radiometer at fronts and occlusions in terms of strong warm, moist air advection in the warm air sector accompanied by convergence in the friction layer. Their quality is far superior to that of analyses based on conventional data, which are shown to yield many inconsistencies.

  6. Field measurements in the wake of a model wind turbine

    NASA Astrophysics Data System (ADS)

    Pol, Suhas; Taylor, Amelia; Bilbao, Argenis; Doostalab, Ali; Novoa, Santiago; Westergaard, Carsten; Hussain, Fazle; Sheng, Jian; Ren, Beibei; Giesselmann, Michael; Glauser, Mark; Castillo, Luciano

    2014-06-01

    As a first step to study the dynamics of a wind farm' we experimentally explored the flow field behind a single wind turbine of diameter 1.17 m at a hub height of 6.25 m. A 10 m tower upstream of the wind farm characterizes the atmospheric conditions and its influence on the wake evolution. A vertical rake of sonic anemometers is clustered around the hub height on a second tower' 6D downstream of the turbine. We present preliminary observations from a 1- hour block of data recorded in near-neutral atmospheric conditions. The ratio of the standard deviation of power to the inflow velocity is greater than three' revealing adverse effects of inflow turbulence on the power and load fluctuations. Furthermore' the wake defect and Reynolds stress and its gradient are pronounced at 6D. The flux of energy due to Reynolds stresses is similar to that reported in wind tunnel studies. The swirl and mixing produces a constant temperature wake which results in a density jump across the wake interface. Further field measurements will explore the dynamics of a model wind farm' including the effects of atmospheric variability.

  7. Magnetic Fields in Massive Stars, Their Winds, and Their Nebulae

    NASA Astrophysics Data System (ADS)

    Walder, Rolf; Folini, Doris; Meynet, Georges

    2012-05-01

    Massive stars are crucial building blocks of galaxies and the universe, as production sites of heavy elements and as stirring agents and energy providers through stellar winds and supernovae. The field of magnetic massive stars has seen tremendous progress in recent years. Different perspectives—ranging from direct field measurements over dynamo theory and stellar evolution to colliding winds and the stellar environment—fruitfully combine into a most interesting and still evolving overall picture, which we attempt to review here. Zeeman signatures leave no doubt that at least some O- and early B-type stars have a surface magnetic field. Indirect evidence, especially non-thermal radio emission from colliding winds, suggests many more. The emerging picture for massive stars shows similarities with results from intermediate mass stars, for which much more data are available. Observations are often compatible with a dipole or low order multi-pole field of about 1 kG (O-stars) or 300 G to 30 kG (Ap/Bp stars). Weak and unordered fields have been detected in the O-star ζ Ori A and in Vega, the first normal A-type star with a magnetic field. Theory offers essentially two explanations for the origin of the observed surface fields: fossil fields, particularly for strong and ordered fields, or different dynamo mechanisms, preferentially for less ordered fields. Numerical simulations yield the first concrete stable (fossil) field configuration, but give contradictory results as to whether dynamo action in the radiative envelope of massive main sequence stars is possible. Internal magnetic fields, which may not even show up at the stellar surface, affect stellar evolution as they lead to a more uniform rotation, with more slowly rotating cores and faster surface rotation. Surface metallicities may become enhanced, thus affecting the mass-loss rates.

  8. Covering (Up?) Katrina: Discursive Ambivalence in Coverage of Hurricane Katrina

    ERIC Educational Resources Information Center

    Berger, Aimee; Cochran, Kate

    2007-01-01

    Long before Katrina, the South functioned in the social imaginary to contain racism and poverty, and the Mason-Dixon acts then in the national imagination as a buffer to safeguard the nation from the taint of such undemocratic realities. More and more, in many countries of America, a system known as "neoliberalism" prevails; based on a…

  9. Public health response to Hurricanes Katrina and Rita--Louisiana, 2005.

    PubMed

    2006-01-20

    On August 24, 2005, Tropical Depression 12 became Tropical Storm Katrina, the 11th named storm of the 2005 Atlantic hurricane season. Late on August 25, Katrina made initial landfall in south Florida as a category 1 hurricane on the Saffir-Simpson Hurricane Scale. Katrina strengthened rapidly upon reaching the Gulf of Mexico, attaining category 5 intensity. On August 29, Hurricane Katrina struck the Gulf Coast near the Louisiana-Mississippi border as a category 3 hurricane. The effect of earlier category 5 wind speeds on Gulf waters and the massive size of the storm combined to create devastating storm-surge conditions for coastal Mississippi, Louisiana, and Alabama and damage as far east as the Florida panhandle. Storm-induced breeches in the New Orleans levee system resulted in the catastrophic flooding of approximately 80% of that city. Hurricane Katrina was the deadliest hurricane to strike the United States since 1928. Preliminary mortality reports indicate approximately 1,000 Katrina-related deaths in Louisiana, 200 in Mississippi, and 20 in Florida, Alabama, and Georgia. PMID:16424853

  10. Public health response to Hurricanes Katrina and Rita--Louisiana, 2005.

    PubMed

    2006-01-20

    On August 24, 2005, Tropical Depression 12 became Tropical Storm Katrina, the 11th named storm of the 2005 Atlantic hurricane season. Late on August 25, Katrina made initial landfall in south Florida as a category 1 hurricane on the Saffir-Simpson Hurricane Scale. Katrina strengthened rapidly upon reaching the Gulf of Mexico, attaining category 5 intensity. On August 29, Hurricane Katrina struck the Gulf Coast near the Louisiana-Mississippi border as a category 3 hurricane. The effect of earlier category 5 wind speeds on Gulf waters and the massive size of the storm combined to create devastating storm-surge conditions for coastal Mississippi, Louisiana, and Alabama and damage as far east as the Florida panhandle. Storm-induced breeches in the New Orleans levee system resulted in the catastrophic flooding of approximately 80% of that city. Hurricane Katrina was the deadliest hurricane to strike the United States since 1928. Preliminary mortality reports indicate approximately 1,000 Katrina-related deaths in Louisiana, 200 in Mississippi, and 20 in Florida, Alabama, and Georgia.

  11. Hosting a Katrina Evacuee.

    NASA Astrophysics Data System (ADS)

    Hoagland, David

    2008-03-01

    No individual or institution anticipated the impact on the academic research community of hurricane Katrina. When Tulane physicist Wayne Reed asked me to host his research group just a day or two after the disaster, with no authorization or understanding of the commitment, I agreed immediately and then pondered implications. Fortunately, colleagues helped in making the commitment real, only the bureaucracy of my public university posing small hindrances. Industry was remarkably generous in providing Reed with significant ``loaner'' equipment, and amazingly, a suite of custom Reed experiments was running within weeks. At the end, the most productive collaborations for Reed seemed not to have been with my group, with its similar research, but to other groups at my institution, particularly the synthetic chemists, who gained access to methods previously unique to Tulane while offering samples previously unique to UMass. Quickly designed projects exploiting this match turned out remarkably productive. Although begun with trepidation, hosting of Reed had huge positive benefits to me and UMass, and I believe, also to Reed and Tulane. Some key lessons for the future: (i) industry has capacity and willingness to help academic research during disruption (ii) commitment of a host institution must be immediate, without a wait for formal approvals or arrangement of special funding -- delay leads only to discouragement, (iii) continuing academic progress of displaced students must come first, and (iv) intellectual synergy rather than overlap should be the basis for seeking a host. Lastly, NSF or other funding agency should consider a program directly addressing the research needs of unexpectedly disrupted academic scientists, and most particularly, graduate students who face greatly extended studies.

  12. Hemispheric Asymmetry in the Auroral Zone Thermospheric Wind Field

    NASA Astrophysics Data System (ADS)

    Conde, M.; Anderson, C.; Davies, T.; Dyson, P. L.; Kosch, M. J.; Singh-Dhadly, M.

    2013-12-01

    We compare climatological average F-region thermospheric wind and temperature fields recorded by the Scanning Doppler Imaging (SDI) Fabry-Perot spectrometer at Mawson Antarctica with climatologies from sites at Poker Flat and Toolik Lake in Alaska. When observing the 630 nm oxygen emission from aurora and airglow, these instruments can map wind and temperature at around 240 km altitude over a circular field of view that is around 1200 km in diameter. The Mawson (glat -67.6, mlat -70.4) SDI was installed in early 2007. It soon became apparent that F-region wind patterns observed at Mawson were morphologically different to those above our pre-existing SDI site at Poker Flat in Alaska, which is located at a similar geographic latitude (65.1) to Mawson, but at a considerably lower geomagnetic latitude (65.4). It was not clear whether these differences were due to hemispheric asymmetries, or just a reflection of the two sites' five degree difference in magnetic latitude. In 2012 we established a new SDI in Alaska at Toolik Lake. The latitude coordinates of this site are 68.6 geographic and 68.5 geomagnetic, which makes it more similar to Mawson. Here we compare the Mawson wind fields with those from the first winter's observations at Toolik Lake, as well as with the historical data from Poker Flat. Availability of a second northern site whose location is more analogous to Mawson will allow us to resolve the extent to which hemispheric asymmetries contribute to differences in F-region wind fields occurring above Mawson and Alaska.

  13. Finding a way back home: a spirituality of exile after Hurricane Katrina.

    PubMed

    DeMoor, Emily Ann

    2009-03-01

    Three years ago breath took the form of Hurricane Katrina and passed through our bodies and our lives, leaving us forever changed. We all breathed her, but for those of us living on the Gulf Coast our encounter with Katrina was more intimate, our breathing more conscious, our memory more charged, our lives forever changed. My story takes me from the winds of Hurricane Katrina blasting through the Gulf Coast, through the tube of a machine that helped keep my son's lung expanded, through the Sinai dessert and the valley of the dry bones, through the in-between spaces of grounded groundlessness, to the forests and rivers of the Berskhire Mountains, where I have relocated and started my life over. My spiritual journey "home" is a dynamic story of Earth, wind, fire, water, flesh, and Spirit.

  14. STEM Progress in Katrina's Wake

    ERIC Educational Resources Information Center

    Gonzales, Dana

    2008-01-01

    When Hurricane Katrina hit New Orleans in 2005, it caused a devastating impact on the Crescent City's public education system. The devastating storm and its aftermath completely wiped out the educational infrastructure of the New Orleans Public Schools, making one of the country's largest metropolitan school districts virtually disappear. Two…

  15. After Katrina, Teachers Reaching Out

    ERIC Educational Resources Information Center

    Perlmutter, David D.

    2005-01-01

    In this article, the author talks about teachers communicating with students to show willingness to listen and care. In cases of real emotional distress, he refers students to the proper campus counseling services, but after Hurricane Katrina, it broke the barriers of his disengagement from students' personal problem. He learned that in many…

  16. Higher Education in Katrina's Wake

    ERIC Educational Resources Information Center

    Fields, Cheryl

    2005-01-01

    Anyone who has ever complained that colleges and universities are highly bureaucratic entities, almost inherently incapable of moving quickly, should be gratified by what we saw in the aftermath of Hurricane Katrina. With amazing swiftness, colleges and universities across the country--from large publics to small privates to community and…

  17. Hurricane Katrina: more lessons learned.

    PubMed

    Stall, Robert S

    2010-11-01

    In August of 2007, the author testified as the medical expert witness on behalf of the State of Louisiana in the St. Rita's Nursing Home criminal case. Thirty-five residents drowned as floodwaters swept over the nursing home during Hurricane Katrina. For nursing home owners, administrators, and medical staff leadership, there are additional lessons to be learned from this catastrophe.

  18. Hurricane Katrina and perinatal health.

    PubMed

    Harville, Emily W; Xiong, Xu; Buekens, Pierre

    2009-12-01

    We review the literature on the effects of Hurricane Katrina on perinatal health, and providing data from our own research on pregnant and postpartum women. After Katrina, obstetric, prenatal, and neonatal care was compromised in the short term, but increases in adverse birth outcomes such as preterm birth, low birthweight, and maternal complications were mostly limited to highly exposed women. Both pregnant and postpartum women had rates of post-traumatic stress disorder similar to, or lower than, others exposed to Katrina, and rates of depression similar to other pregnant and postpartum populations. Health behaviors, such as smoking and breastfeeding, may have been somewhat negatively affected by the disaster, whereas effects on nutrition were likely associated with limited time, money, and food choices, and indicated by both weight gain and loss. We conclude that, with a few specific exceptions, postdisaster concerns and health outcomes for pregnant and postpartum women were similar to those of other people exposed to Hurricane Katrina. In such situations, disaster planners and researchers should focus on providing care and support for the normal concerns of the peripartum period, such as breastfeeding, depression, and smoking cessation. Contraception needs to be available for those who do not want to become pregnant. Although additional physical and mental health care needs to be provided for the most severely exposed women and their babies, many women are capable of surviving and thriving in postdisaster environments.

  19. Lessons: Katrina and Beginning Anew

    ERIC Educational Resources Information Center

    Kirylo, James D.

    2005-01-01

    New Orleans, fondly known in better days for its spectacular cuisine, cool jazz, and good times, was the leading story on television news broadcasts the world over when a massive hurricane came. As Katrina took its destructive path, culminating in the devastating rupture of ill-prepared levee systems, the world was riveted by stories about the…

  20. The Immigrant Children of Katrina

    ERIC Educational Resources Information Center

    Reyes, Augustina H.

    2010-01-01

    In August 2005, Hurricane Katrina displaced the largest number of public school children ever affected by any disaster. Approximately 370,000 children, including 15,000 Latino/Hispanic children from Louisiana, were scattered throughout the 48 U.S. states (Landrieu, 2010; Louisiana Department of Education, 2004). Although much of the media…

  1. Hurricane Katrina: A Teachable Moment

    ERIC Educational Resources Information Center

    Bertrand, Peggy

    2009-01-01

    This article presents suggestions for integrating the phenomenon of hurricanes into the teaching of high school fluid mechanics. Students come to understand core science concepts in the context of their impact upon both the environment and human populations. Suggestions for using information about hurricanes, particularly Hurricane Katrina, in a…

  2. Prediction of the far field noise from wind energy farms

    NASA Technical Reports Server (NTRS)

    Shepherd, K. P.; Hubbard, H. H.

    1986-01-01

    The basic physical factors involved in making predictions of wind turbine noise and an approach which allows for differences in the machines, the wind energy farm configurations and propagation conditions are reviewed. Example calculations to illustrate the sensitivity of the radiated noise to such variables as machine size, spacing and numbers, and such atmosphere variables as absorption and wind direction are presented. It is found that calculated far field distances to particular sound level contours are greater for lower values of atmospheric absorption, for a larger total number of machines, for additional rows of machines and for more powerful machines. At short and intermediate distances, higher sound pressure levels are calculated for closer machine spacings, for more powerful machines, for longer row lengths and for closer row spacings.

  3. SMART wind turbine rotor. Design and field test

    SciTech Connect

    Berg, Jonathan Charles; Resor, Brian Ray; Paquette, Joshua A.; White, Jonathan Randall

    2014-01-01

    The Wind Energy Technologies department at Sandia National Laboratories has developed and field tested a wind turbine rotor with integrated trailing-edge flaps designed for active control of rotor aerodynamics. The SMART Rotor project was funded by the Wind and Water Power Technologies Office of the U.S. Department of Energy (DOE) and was conducted to demonstrate active rotor control and evaluate simulation tools available for active control research. This report documents the design, fabrication, and testing of the SMART Rotor. This report begins with an overview of active control research at Sandia and the objectives of this project. The SMART blade, based on the DOE / SNL 9-meter CX-100 blade design, is then documented including all modifications necessary to integrate the trailing edge flaps, sensors incorporated into the system, and the fabrication processes that were utilized. Finally the test site and test campaign are described.

  4. Cooperative field test program for wind systems. Final report

    SciTech Connect

    Bollmeier, W.S. II; Dodge, D.M.

    1992-03-01

    The objectives of the Federal Wind Energy Program, managed by the US Department of Energy (DOE), are (1) to assist industry and utilities in achieving a multi-regional US market penetration of wind systems, and (2) to establish the United States as the world leader in the development of advanced wind turbine technology. In 1984, the program conducted a series of planning workshops with representatives from the wind energy industry to obtain input on the Five-Year Research Plan then being prepared by DOE. One specific suggestion that came out of these meetings was that the federal program should conduct cooperative research tests with industry to enhance the technology transfer process. It was also felt that the active involvement of industry in DOE-funded research would improve the state of the art of wind turbine technology. DOE established the Cooperative Field Test Program (CFTP) in response to that suggestion. This program was one of the first in DOE to feature joint industry-government research test teams working toward common objectives.

  5. Field Wind Tunnel Assessment of the Potential for Wind Transport of Soils

    SciTech Connect

    Lancaster, Nicholas; Metzger, Steve

    2005-02-01

    This report documents a series of field experiments carried out in the Double Tracks area of the Tonopah Test Range in June, July, and August 1996 and March and July 1997. The aim of the experiments was to: (1) determine the wind speeds necessary to entrain surface particles from excavated surfaces in the study area and (2) determine dust emissions from surfaces that had been stabilized permanently by planted natural vegetation. This investigation assessed the potential for wind transport of surface soils, including resuspension and emission of dust sized particles from areas of surface heavy metal contamination, following site remediation, as well as the actual emissions from these areas. The remediation site is located in Area 73 of the Tonopah Test Range. The goal of the field experiments was to measure the velocities with which boundary layer winds might initiate dust emissions from the affected site, and to gage the effectiveness of surface stabilization procedures to prevent such emissions. Particle movement measurements were generated through the use of a portable wind tunnel laid directly on the excavated surface.

  6. Simulating Turbulent Wind Fields for Offshore Turbines in Hurricane-Prone Regions (Poster)

    SciTech Connect

    Guo, Y.; Damiani, R.; Musial, W.

    2014-04-01

    Extreme wind load cases are one of the most important external conditions in the design of offshore wind turbines in hurricane prone regions. Furthermore, in these areas, the increase in load with storm return-period is higher than in extra-tropical regions. However, current standards have limited information on the appropriate models to simulate wind loads from hurricanes. This study investigates turbulent wind models for load analysis of offshore wind turbines subjected to hurricane conditions. Suggested extreme wind models in IEC 61400-3 and API/ABS (a widely-used standard in oil and gas industry) are investigated. The present study further examines the wind turbine response subjected to Hurricane wind loads. Three-dimensional wind simulator, TurbSim, is modified to include the API wind model. Wind fields simulated using IEC and API wind models are used for an offshore wind turbine model established in FAST to calculate turbine loads and response.

  7. Sustainability: a view from the wind-eroded field.

    PubMed

    Warren, Andrew

    2007-01-01

    This article explores the assessment of sustainability in fields subject to wind erosion. In the first part, simple sustainability audits are examined, as of soil depth and nutrients. Direct measurement of these characteristics has many problems, largely because of huge variability in space and time at all scales. Modelling still has its problems, but it may be possible to overcome many of them soon. It is true that wind erosion preferentially removes soil nutrients, but there are imponderables even here. The nutrient balance in many of these soils includes considerable input from dust. In West Africa, it has been shown that the amounts of calcium and potassium that are added in dust are sufficient to fertilize dispersed crops. In mildly acidic sandy soils, such as those found on the widespread palaeoaeolian deposits, much of the phosphorus is fixed and unavailable to plants by the time it is removed by wind erosion, so that erosion has no added downside. Most of the nutrients carried by dust have been shown to travel close to the ground (even when they are attached to dust-sized particles), and so are trapped in nearby fallow strips, and are thus not lost to the farming system. Second, the sustainability of a whole semi-arid farming system is explored. Wind erosion in semi-arid areas (like China, the Sahel and Northwestern Europe) generally takes place on aeolian deposits of the recent geological past. Most of these soils are deep enough to withstand centuries of wind erosion before they are totally lost to production, and some of these soils have greater fertility at greater depth (so that wind erosion may even improve the soil). Finally some remarks are made about environmental change in relation to sustainability.

  8. Sustainability: a view from the wind-eroded field.

    PubMed

    Warren, Andrew

    2007-01-01

    This article explores the assessment of sustainability in fields subject to wind erosion. In the first part, simple sustainability audits are examined, as of soil depth and nutrients. Direct measurement of these characteristics has many problems, largely because of huge variability in space and time at all scales. Modelling still has its problems, but it may be possible to overcome many of them soon. It is true that wind erosion preferentially removes soil nutrients, but there are imponderables even here. The nutrient balance in many of these soils includes considerable input from dust. In West Africa, it has been shown that the amounts of calcium and potassium that are added in dust are sufficient to fertilize dispersed crops. In mildly acidic sandy soils, such as those found on the widespread palaeoaeolian deposits, much of the phosphorus is fixed and unavailable to plants by the time it is removed by wind erosion, so that erosion has no added downside. Most of the nutrients carried by dust have been shown to travel close to the ground (even when they are attached to dust-sized particles), and so are trapped in nearby fallow strips, and are thus not lost to the farming system. Second, the sustainability of a whole semi-arid farming system is explored. Wind erosion in semi-arid areas (like China, the Sahel and Northwestern Europe) generally takes place on aeolian deposits of the recent geological past. Most of these soils are deep enough to withstand centuries of wind erosion before they are totally lost to production, and some of these soils have greater fertility at greater depth (so that wind erosion may even improve the soil). Finally some remarks are made about environmental change in relation to sustainability. PMID:17915712

  9. Magnetic holes in the solar wind. [(interplanetary magnetic fields)

    NASA Technical Reports Server (NTRS)

    Turner, J. M.; Burlaga, L. F.; Ness, N. F.; Lemaire, J. F.

    1976-01-01

    An analysis is presented of high resolution interplanetary magnetic field measurements from the magnetometer on Explorer 43 which showed that low magnetic field intensities in the solar wind at 1 AU occur as distinct depressions or 'holes'. These magnetic holes are new kinetic-scale phenomena, having a characteristic dimension on the order of 20,000 km. They occurred at a rate of 1.5/day in the 18-day time span (March 18 to April 6, 1971) that was analyzed. Most of the magnetic holes are characterized by both a depression in the absolute value of the magnetic field, and a change in the magnetic field direction; some of these are possibly the result of magnetic merging. However, in other cases the magnetic field direction does not change; such holes are not due to magnetic merging, but might be a diamagnetic effect due to localized plasma inhomogeneities.

  10. ENVIRONMENTAL CONDITIONS IN NORTHERN GULF OF MEXICO COASTAL WATERS FOLLOWING HURRICANE KATRINA

    EPA Science Inventory

    On the morning of August 29, 2005 Hurricane Katrina struck the coast of Louisiana, between New Orleans and Biloxi, Mississippi, as a strong category three hurricane on the Saffir-Simpson scale. The massive winds and flooding had the potential for a tremendous environmental impac...

  11. Lessons Learned from a Bout with Hurricane Katrina: The Delgado College Community Story

    ERIC Educational Resources Information Center

    Johnson, Alex B.; Nolan, Gayle; Siegrist, Cynthia

    2006-01-01

    When Hurricane Katrina struck the Gulf Coast on August 29, 2005, it inflicted wind and flooding damage on all but one of the five campuses and centers of Delgado Community College, the oldest and largest two-year institution in Louisiana. Hardest hit was Delgado's main location, the City Park Campus in New Orleans, where three to six feet of flood…

  12. Magnetic Fields in Supernova Remnants and Pulsar-Wind Nebulae

    NASA Astrophysics Data System (ADS)

    Reynolds, Stephen P.; Gaensler, B. M.; Bocchino, Fabrizio

    2012-05-01

    We review the observations of supernova remnants (SNRs) and pulsar-wind nebulae (PWNe) that give information on the strength and orientation of magnetic fields. Radio polarimetry gives the degree of order of magnetic fields, and the orientation of the ordered component. Many young shell supernova remnants show evidence for synchrotron X-ray emission. The spatial analysis of this emission suggests that magnetic fields are amplified by one to two orders of magnitude in strong shocks. Detection of several remnants in TeV gamma rays implies a lower limit on the magnetic-field strength (or a measurement, if the emission process is inverse-Compton upscattering of cosmic microwave background photons). Upper limits to GeV emission similarly provide lower limits on magnetic-field strengths. In the historical shell remnants, lower limits on B range from 25 to 1000 μG. Two remnants show variability of synchrotron X-ray emission with a timescale of years. If this timescale is the electron-acceleration or radiative loss timescale, magnetic fields of order 1 mG are also implied. In pulsar-wind nebulae, equipartition arguments and dynamical modeling can be used to infer magnetic-field strengths anywhere from ˜5 μG to 1 mG. Polarized fractions are considerably higher than in SNRs, ranging to 50 or 60% in some cases; magnetic-field geometries often suggest a toroidal structure around the pulsar, but this is not universal. Viewing-angle effects undoubtedly play a role. MHD models of radio emission in shell SNRs show that different orientations of upstream magnetic field, and different assumptions about electron acceleration, predict different radio morphology. In the remnant of SN 1006, such comparisons imply a magnetic-field orientation connecting the bright limbs, with a substantial density gradient across the remnant.

  13. A wind tunnel application of large-field focusing schlieren

    NASA Technical Reports Server (NTRS)

    Ponton, Michael K.; Seiner, John M.; Mitchell, L. K.; Manning, James C.; Jansen, Bernard J.; Lagen, Nicholas T.

    1992-01-01

    A large-field focusing schlieren apparatus was installed in the NASA Lewis Research Center 9 by 15 foot wind tunnel in an attempt to determine the density gradient flow field of a free jet issuing from a supersonic nozzle configuration. The nozzle exit geometry was designed to reduce acoustic emissions from the jet by enhancing plume mixing. Thus, the flow exhibited a complex three-dimensional structure which warranted utilizing the sharp focusing capability of this type of schlieren method. Design considerations concerning tunnel limitations, high-speed photography, and video tape recording are presented in the paper.

  14. Solar wind magnetic field bending of Jovian dust trajectories.

    PubMed

    Zook, H A; Grün, E; Baguhl, M; Hamilton, D P; Linkert, G; Liou, J; Forsyth, R; Phillips, J L

    1996-11-29

    From September 1991 to October 1992, the cosmic dust detector on the Ulysses spacecraft recorded 11 short bursts, or streams, of dust. These dust grains emanated from the jovian system, and their trajectories were strongly affected by solar wind magnetic field forces. Analyses of the on-board measurements of these fields, and of stream approach directions, show that stream-associated dust grain masses are of the order of 10(-18) gram and dust grain velocities exceed 200 kilometers per second. These masses and velocities are, respectively, about 10(3) times less massive and 5 to 10 times faster than earlier reported. PMID:8929405

  15. Disaster response. Natural disaster: Katrina.

    PubMed

    McSwain, Norman E

    2010-07-01

    The aftermath and response to a disaster can be divided into four phases. The importance of each depends on the length of time without resupply and the resources that are required. This in turn depends on the time span of the disaster; the area involved; the number of the population affected; the resupply available; the extent of the devastation; and the size of the evacuation. The above phases are discussed using hurricane Katrina as an example. The phases are as follows: immediate response, evacuation, backfill and resupply, and restoration. The restoration phase is usually the longest and requires the most resources. This article addresses the situation of Katrina, the mistakes that were made, the lessons that were learned, and the solutions that are needed. Appropriate training and practice are required for all participants using realistic scenarios.

  16. Wind Field and Trajectory Models for Tornado-Propelled Objects

    NASA Technical Reports Server (NTRS)

    Redmann, G. H.; Radbill, J. R.; Marte, J. E.; Dergarabedian, P.; Fendell, F. E.

    1978-01-01

    A mathematical model to predict the trajectory of tornado born objects postulated to be in the vicinity of nuclear power plants is developed. An improved tornado wind field model satisfied the no slip ground boundary condition of fluid mechanics and includes the functional dependence of eddy viscosity with altitude. Subscale wind tunnel data are obtained for all of the missiles currently specified for nuclear plant design. Confirmatory full-scale data are obtained for a 12 inch pipe and automobile. The original six degree of freedom trajectory model is modified to include the improved wind field and increased capability as to body shapes and inertial characteristics that can be handled. The improved trajectory model is used to calculate maximum credible speeds, which for all of the heavy missiles are considerably less than those currently specified for design. Equivalent coefficients for use in three degree of freedom models are developed and the sensitivity of range and speed to various trajectory parameters for the 12 inch diameter pipe are examined.

  17. Doppler lidar studies of atmospheric wind field dynamics

    NASA Technical Reports Server (NTRS)

    Hardesty, R. M.; Post, M. J.; Lawrence, T. R.; Hall, F. F., Jr.

    1986-01-01

    For the past 5 years the Wave Propagation Lab. has operated a pulsed CO2 Doppler lidar system to evaluate coherent laser radar technology and to investigate applications of the technique in atmospheric research. The capability of the system to provide measurements of atmospheric winds, backscatter, and water vapor has been extensively studied over this period. Because Doppler lidar can measure atmospheric wind structure in the clear air without degradation by terrain features, it offers a unique capability as a research tool for studies of many transient or local scale atmospheric events. This capability was demonstrated in recent field experiments near Boulder, Colo. and Midland, Tex., in which the lidar clearly depicted the wind field structure associated with several types of phenomena, including thunderstorm microbursts, valley drainage flow, and passage of a dryline front. To improve sensitivity during the periods of low aerosol backscatter, the system has recently been upgraded with new transmitter/receiver hardware. The upgraded system, which transmit 2 J per pulse of output energy at a rate of 50 Hz and incorporates computer control for automated operation, underwent calibration testing during the spring of 1986.

  18. Hurricane Katrina as a "teachable moment"

    NASA Astrophysics Data System (ADS)

    Glantz, M. H.

    2008-04-01

    By American standards, New Orleans is a very old, very popular city in the southern part of the United States. It is located in Louisiana at the mouth of the Mississippi River, a river which drains about 40% of the Continental United States, making New Orleans a major port city. It is also located in an area of major oil reserves onshore, as well as offshore, in the Gulf of Mexico. Most people know New Orleans as a tourist hotspot; especially well-known is the Mardi Gras season at the beginning of Lent. People refer to the city as the "Big Easy". A recent biography of the city refers to it as the place where the emergence of modern tourism began. A multicultural city with a heavy French influence, it was part of the Louisiana Purchase from France in early 1803, when the United States bought it, doubling the size of the United States at that time. Today, in the year 2007, New Orleans is now known for the devastating impacts it withstood during the onslaught of Hurricane Katrina in late August 2005. Eighty percent of the city was submerged under flood waters. Almost two years have passed, and many individuals and government agencies are still coping with the hurricane's consequences. And insurance companies have been withdrawing their coverage for the region. The 2005 hurricane season set a record, in the sense that there were 28 named storms that calendar year. For the first time in hurricane forecast history, hurricane forecasters had to resort to the use of Greek letters to name tropical storms in the Atlantic and Gulf (Fig.~1). Hurricane Katrina was a Category 5 hurricane when it was in the middle of the Gulf of Mexico, after having passed across southern Florida. At landfall, Katrina's winds decreased in speed and it was relabeled as a Category 4. It devolved into a Category 3 hurricane as it passed inland when it did most of its damage. Large expanses of the city were inundated, many parts under water on the order of 20 feet or so. The Ninth Ward, heavily

  19. Computations of wind-driven ocean-induced magnetic fields

    NASA Astrophysics Data System (ADS)

    Sachl, Libor; Einspigel, David; Martinec, Zdenek

    2016-04-01

    We present the results of computations of the secondary magnetic field induced by ocean motions. Ocean velocities are computed using the baroclinic ocean model LSOMG. The velocities are then used to determine the Lorentz force which is plugged into the magnetic induction code TLAM as a principal forcing. The TLAM is a 2D magnetic induction code based on the thin-shell approximation (Vivier et al., 2004; Tyler et al., 1997). In this approximation, the equation of magnetic induction simplifies significantly, time derivatives of main and induced magnetic fields are neglected as well as the self-induction term. The price for simplification of governing equations is the limited applicability of the resulting system. It is only suitable for slowly evolving processes. In order to meet the condition, we restrict ourselves to the wind (buoyancy) driven ocean circulation, although the LSOMG model is able to model both tidally- and wind-driven circulations. We assess the accuracy of thin-shell approximation in our setup by comparing the results with the Swarm satellite magnetic data. References Tyler, R. H., Mysak, L. A., and Oberhuber, J. M, 1997. Electromagnetic fields generated by a three dimensional global ocean circulation. J. Geophys. Res., 102, 5531-5551. Vivier, F., Meier-Reimer, E., and Tyler, R. H., 2004. Simulations of magnetic fields generated by the Antarctic Circumpolar Current at satellite altitude: Can geomagnetic measurements be used to monitor the flow? Geophys. Res. Lett., 31, L10306, doi:10.1029/2004GL019804.

  20. Magnetic Field Rotations at Kinetic Scales in the Solar Wind

    NASA Astrophysics Data System (ADS)

    Chen, Christopher; Matteini, Lorenzo; Burgess, David; Horbury, Timothy

    2015-04-01

    The distribution of spatial angle changes in the solar wind magnetic field is usually attributed to a mixture of turbulence and other structures. Recent results have suggested that in the MHD inertial range this distribution may be scale invariant, generated by the turbulence, and consist mainly of field rotations. Here, we examine the distribution of magnetic field rotations in the smaller scale kinetic range (from ion to electron scales), where the turbulence is thought to be dissipated, using combined fluxgate/search-coil magnetometer data from Cluster. The degree of self-similarity is measured and the spatial distribution of the fluctuations at different scales is compared. At ion scales, the energy in angle rotations larger than α drops exponentially with α with e-folding ~10°, and at electron scales with e-folding

  1. Mortality associated with Hurricane Katrina--Florida and Alabama, August-October 2005.

    PubMed

    2006-03-10

    On August 25, 2005, Hurricane Katrina made landfall between Hallandale Beach and Aventura, Florida, as a Category 1 hurricane, with sustained winds of 80 mph. Storm effects, primarily rain, flooding, and high winds, were substantial; certain areas reported nearly 12 inches of rainfall. After crossing southern Florida and entering the Gulf of Mexico, the hurricane strengthened and made landfall in southeastern Louisiana on August 29 as a Category 3 hurricane, with sustained winds of 125 mph. Katrina was one of the strongest hurricanes to strike the United States during the past 100 years and was likely the nation's costliest natural disaster to date. This report summarizes findings and recommendations from a review of mortality records of Florida's Medical Examiners Commission (FMEC) and the Alabama Department of Forensic Science (ADFS). CDC was invited by the Florida Department of Health (FDOH) and the Alabama Department of Public Health (ADPH) to assess the mortality related to Hurricane Katrina. The mortality review was intended to provide county-based information that would be used to 1) define the impact of the hurricane, 2) describe the etiology of deaths, and 3) identify strategies to prevent or reduce future hurricane-related mortality. Combined, both agencies identified five, 23, and 10 deaths, respectively, that were directly, indirectly, or possibly related to Hurricane Katrina. Information from the characterization of these deaths will be used to reduce hurricane-related mortality through early community awareness of hurricane-related risk, prevention measures, and effective communication of a coordinated hurricane response plan.

  2. Wind field estimation and its utilization in trajectory and input prediction

    NASA Astrophysics Data System (ADS)

    Kampoon, Jane-Wit

    This dissertation work develops a method for onboard estimation of wind field with spatial and temporal variation based on local wind vector estimation and/or measurements from multiple aircraft flying in the same airspace. Aircraft flying in the same airspace of operation are considered airborne wind sensors scattered over the airspace because of the fact that aircraft carry along with them wind information inherent in their dynamics and kinematics. The onboard wind field estimation is formulated in the framework of parameter estimation based on various wind field models, which are different function of position and time. The online wind field estimation is utilized in trajectory prediction of aircraft in spatially and temporally varying wind. Various simulation cases are presented to demonstrate the feasibility of wind field estimation and the benefit of using such information in trajectory prediction. Further this dissertation presents a method of input prediction for and aircraft flying in spatially and temporally varying wind field. Input prediction is done using inverse simulation to compute the required control variables (control surface deflections and thrust level) for an aircraft to fly through a prescribed trajectory. Estimated wind field is also used in inverse simulation for input prediction as in the trajectory prediction case. Various simulation cases are presented to demonstrate the feasibility of input prediction method and the importance of including wind field information in inverse simulations.

  3. GroundWinds 2000 field campaign: demonstration of new Doppler lidar technology and wind lidar data intercomparison

    NASA Astrophysics Data System (ADS)

    Yoe, James G.; Varma Raja, M. K. Rama; Hardesty, R. Michael; Brewer, W. Alan; Moore, Berrien, III; Ryan, James M.; Hays, Paul B.; Nardell, Carl A.; Gentry, Bruce M.; Day, Michelle; Rancourt, Kenneth

    2003-03-01

    A field campaign featuring three collocated Doppler wind lidars was conducted over ten days during September 2000 at the GroundWinds Observatory in New Hampshire. The lidars were dissimilar in wavelength and Doppler detection method. The GroundWinds lidar operated at 532 nm and used fringe-imaging direct detection, while the Goddard Lidar Observatory for Winds (GLOW) ran at 355 nm and employed double-edge filter direct detection, and the NOAA mini-MOPA operated at 10 microns and used heterodyne detection. The objectives of the campaign were (1) to demonstrate the capability of the GroundWinds lidar to measure winds while employing several novel components, and (2) to compare directly the radial wind velocities measured by the three lidars for as wide a variety of conditions as possible. Baseline wind profiles and ancillary meteorological data (temperature and humidity profiles) were obtained by launching GPS radiosondes from the observatory as frequently as every 90 minutes. During the final week of the campaign the lidars collected data along common lines-of-sight for several extended periods. The wind speed varied from light to jet stream values, and sky conditions ranged from clear to thick clouds. Intercomparisons of overlapping lidar and radiosonde observations show that all three lidars were able to measure wind given sufficient backscatter. At ranged volumes containing thicker clouds, and those beyond, the wind sensing capability of the direct detection lidars was adversely affected.

  4. Impacts of Hurricane Katrina on floodplain forests of the Pearl River: Chapter 6A in Science and the storms-the USGS response to the hurricanes of 2005

    USGS Publications Warehouse

    Faulkner, Stephen; Barrow, Wylie; Couvillion, Brady R.; Conner, William; Randall, Lori; Baldwin, Michael

    2007-01-01

    Floodplain forests are an important habitat for Neotropical migratory birds. Hurricane Katrina passed through the Pearl River flood plain shortly after making landfall. Field measurements on historical plots and remotely sensed data were used to assess the impact of Hurricane Katrina on the structure of floodplain forests of the Pearl River.

  5. Variance Anisotropy of Solar Wind Velocity and Magnetic Field Fluctuations

    NASA Astrophysics Data System (ADS)

    Oughton, S.; Matthaeus, W. H.; Wan, M.

    2015-12-01

    At MHD scales in the solar wind, velocity and magnetic fieldfluctuations are typically observed to have much more energy in thecomponents transverse to the mean magnetic field, relative to theparallel components [eg, 1,2]. This is often referred to asvariance anisotropy. Various explanations for it have been suggested,including that the fluctuations are predominantly shear Alfvén waves[1] and that turbulent dynamics leads to such states [eg, 3].Here we investigate the origin and strength of such varianceanisotropies, using spectral method simulations of thecompressible (polytropic) 3D MHD equations. We report on results from runs with several different classes ofinitial conditions. These classes include(i) fluctuations polarized only in the same sense as shear Alfvénwaves (aka toroidal polarization),(ii) randomly polarized fluctuations, and(iii) fluctuations restricted so that most of the energy is inmodes which have their wavevectors perpendicular, or nearly so, to thebackground magnetic field: quasi-2D modes. The plasma beta and Mach number dependence [4] of quantities like the variance anisotropy, Alfven ratio, and fraction of the energy in the toroidal fluctuations will be examined, along with the timescales for the development of any systematic features.Implications for solar wind fluctuations will be discussed. References:[1] Belcher & Davis 1971, J. Geophys. Res, 76, 3534.[2] Oughton et al 2015, Phil Trans Roy Soc A, 373, 20140152.[3] Matthaeus et al 1996, J. Geophys. Res, 101, 7619.[4] Smith et al 2006, J. Geophys. Res, 111, A09111.

  6. Observation of high-resolution wind fields and offshore wind turbine wakes using TerraSAR-X imagery

    NASA Astrophysics Data System (ADS)

    Gies, Tobias; Jacobsen, Sven; Lehner, Susanne; Pleskachevsky, Andrey

    2014-05-01

    1. Introduction Numerous large-scale offshore wind farms have been built in European waters and play an important role in providing renewable energy. Therefore, knowledge of behavior of wakes, induced by large wind turbines and their impact on wind power output is important. The spatial variation of offshore wind turbine wake is very complex, depending on wind speed, wind direction, ambient atmospheric turbulence and atmospheric stability. In this study we demonstrate the application of X-band TerraSAR-X (TS-X) data with high spatial resolution for studies on wind turbine wakes in the near and far field of the offshore wind farm Alpha Ventus, located in the North Sea. Two cases which different weather conditions and different wake pattern as observed in the TS-X image are presented. 2. Methods The space-borne synthetic aperture radar (SAR) is a unique sensor that provides two-dimensional information on the ocean surface. Due to their high resolution, daylight and weather independency and global coverage, SARs are particularly suitable for many ocean and coastal applications. SAR images reveal wind variations on small scales and thus represent a valuable means in detailed wind-field analysis. The general principle of imaging turbine wakes is that the reduced wind speed downstream of offshore wind farms modulates the sea surface roughness, which in turn changes the Normalized Radar Cross Section (NRCS, denoted by σ0) in the SAR image and makes the wake visible. In this study we present two cases at the offshore wind farm Alpha Ventus to investigate turbine-induced wakes and the retrieved sea surface wind field. Using the wind streaks, visible in the TS-X image and the shadow behind the offshore wind farm, induced by turbine wake, the sea surface wind direction is derived and subsequently the sea surface wind speed is calculated using the latest generation of wind field algorithm XMOD2. 3. Case study alpha ventus Alpha Ventus is located approximately 45 km from the

  7. Lessons Learnt From Hurricane Katrina.

    NASA Astrophysics Data System (ADS)

    Akundi, Murty

    2008-03-01

    Hurricane Katrina devastated New Orleans and its suburbs on Monday August 29^th, 2005. The previous Friday morning, August 26, the National Hurricane Center indicated that Katrina was a Category One Hurricane, which was expected to hit Florida. By Friday afternoon, it had changed its course, and neither the city nor Xavier University was prepared for this unexpected turn in the hurricane's path. The university had 6 to 7 ft of water in every building and Xavier was closed for four months. Students and university personnel that were unable to evacuate were trapped on campus and transportation out of the city became a logistical nightmare. Email and all electronic systems were unavailable for at least a month, and all cell phones with a 504 area code stopped working. For the Department, the most immediate problem was locating faculty and students. Xavier created a list of faculty and their new email addresses and began coordinating with faculty. Xavier created a web page with advice for students, and the chair of the department created a separate blog with contact information for students. The early lack of a clear method of communication made worse the confusion and dismay among the faculty on such issues as when the university would reopen, whether the faculty would be retained, whether they should seek temporary (or permanent) employment elsewhere, etc. With the vision and determination of President Dr. Francis, Xavier was able to reopen the university in January and ran a full academic year from January through August. Since Katrina, the university has asked every department and unit to prepare emergency preparedness plans. Each department has been asked to collect e-mail addresses (non-Xavier), cell phone numbers and out of town contact information. The University also established an emergency website to communicate. All faculty have been asked to prepare to teach classes electronically via Black board or the web. Questions remain about the longer term issues of

  8. Three Dimensional Dynamic Model Based Wind Field Reconstruction from Lidar Data

    NASA Astrophysics Data System (ADS)

    Raach, Steffen; Schlipf, David; Haizmann, Florian; Cheng, Po Wen

    2014-06-01

    Using the inflowing horizontal and vertical wind shears for individual pitch controller is a promising method if blade bending measurements are not available. Due to the limited information provided by a lidar system the reconstruction of shears in real-time is a challenging task especially for the horizontal shear in the presence of changing wind direction. The internal model principle has shown to be a promising approach to estimate the shears and directions in 10 minutes averages with real measurement data. The static model based wind vector field reconstruction is extended in this work taking into account a dynamic reconstruction model based on Taylor's Frozen Turbulence Hypothesis. The presented method provides time series over several seconds of the wind speed, shears and direction, which can be directly used in advanced optimal preview control. Therefore, this work is an important step towards the application of preview individual blade pitch control under realistic wind conditions. The method is tested using a turbulent wind field and a detailed lidar simulator. For the simulation, the turbulent wind field structure is flowing towards the lidar system and is continuously misaligned with respect to the horizontal axis of the wind turbine. Taylor's Frozen Turbulence Hypothesis is taken into account to model the wind evolution. For the reconstruction, the structure is discretized into several stages where each stage is reduced to an effective wind speed, superposed with a linear horizontal and vertical wind shear. Previous lidar measurements are shifted using again Taylor's Hypothesis. The wind field reconstruction problem is then formulated as a nonlinear optimization problem, which minimizes the residual between the assumed wind model and the lidar measurements to obtain the misalignment angle and the effective wind speed and the wind shears for each stage. This method shows good results in reconstructing the wind characteristics of a three dimensional

  9. Observations of oceanic surface-wind fields from the Nimbus-7 microwave radiometer

    NASA Technical Reports Server (NTRS)

    Miller, J. R.; Geyser, J. E.; Chang, A. T. C.; Wilheit, T. T., Jr.

    1982-01-01

    Brightness temperatures from the five-frequency dual-polarized scanning multichannel microwave radiometer (SMMR) on Nimbus 7 have been used to obtain surface wind fields over the ocean. The satellite-derived wind field for 1200Z, Feb. 19, 1979, in the eastern North Pacific has been compared with an operationally generated surface-wind analysis field. Previous point comparisons at selected locations have indicated that satellite winds are accurate to 3 m/sec. The results, although of a preliminary nature, indicate that SMMR-derived winds may be used to determine large-scale wind fields over the ocean, particularly in areas of strong wind gradients such as found in cyclonic systems.

  10. Mental illness and suicidality after Hurricane Katrina.

    PubMed Central

    Kessler, Ronald C.; Galea, Sandro; Jones, Russell T.; Parker, Holly A.

    2006-01-01

    OBJECTIVE: To estimate the impact of Hurricane Katrina on mental illness and suicidality by comparing results of a post-Katrina survey with those of an earlier survey. METHODS: The National Comorbidity Survey-Replication, conducted between February 2001 and February 2003, interviewed 826 adults in the Census Divisions later affected by Hurricane Katrina. The post-Katrina survey interviewed a new sample of 1043 adults who lived in the same area before the hurricane. Identical questions were asked about mental illness and suicidality. The post-Katrina survey also assessed several dimensions of personal growth that resulted from the trauma (for example, increased closeness to a loved one, increased religiosity). Outcome measures used were the K6 screening scale of serious mental illness and mild-moderate mental illness and questions about suicidal ideation, plans and attempts. FINDINGS: Respondents to the post-Katrina survey had a significantly higher estimated prevalence of serious mental illness than respondents to the earlier survey (11.3% after Katrina versus 6.1% before; chi(2)1= 10.9; P < 0.001) and mild-moderate mental illness (19.9% after Katrina versus 9.7% before; chi(2)1 = 22.5; P < 0.001). Among respondents estimated to have mental illness, though, the prevalence of suicidal ideation and plans was significantly lower in the post-Katrina survey (suicidal ideation 0.7% after Katrina versus 8.4% before; chi(2)1 = 13.1; P < 0.001; plans for suicide 0.4% after Katrina versus 3.6% before; chi(2)1 = 6.0; P = 0.014). This lower conditional prevalence of suicidality was strongly related to two dimensions of personal growth after the trauma (faith in one's own ability to rebuild one's life, and realization of inner strength), without which between-survey differences in suicidality were insignificant. CONCLUSION: Despite the estimated prevalence of mental illness doubling after Hurricane Katrina, the prevalence of suicidality was unexpectedly low. The role of post

  11. A review of wind field models for atmospheric transport

    SciTech Connect

    Ramsdell, J.V. Jr.; Skyllingstad, E.D.

    1993-06-01

    The primary objective of the Hanford Environmental Dose Reconstruction (HEDR) Project is to estimate the radiation dose that individuals could have received as a result of emissions since 1944 from the US Department of Energy`s (DOE) Hanford Site near Richland, Washington. The HEDR Project is developing a computer code to estimate these doses and their uncertainties. The code, known as the HEDR integrated Code (HEDRIC), consists of four separate component codes. One of the component codes, called the Regional Atmospheric Transport Code for Hanford Emission Tracking (RATCHET) combines meteorological and release data to estimate time-integrated air concentrations and surface contamination at specific locations in the vicinity of the Hanford Site. The RATCHET domain covers approximately 75,000 square miles, extending from the crest of the Cascade Mountains on the west to the eastern edge of the Idaho panhandle and from central Oregon on the south to the Canadian border. This letter report explains the procedures in RATCHET that transform observed wind data into the wind fields used in atmospheric transport calculations. It also describes and evaluates alternative procedures not selected for use in RATCHET.

  12. Remote Sensing of the 3D Wind and Turbulence Field by Coherent Doppler Lidars for Wind Power Applications

    NASA Astrophysics Data System (ADS)

    Sjöholm, M.; Courtney, M. S.; Enevoldsen, K. M.; Lindelöw, P.; Mann, J.; Mikkelsen, T.

    2008-12-01

    For several decades Risø DTU has been involved in wind power meteorology and during the last half- decade the performance of commercially available coherent wind Doppler Lidars have been extensively studied at the test station for large wind turbines, Høvsøre, in Western Jutland, Denmark. One aspect of wind Lidars, in contrast to many in-situ wind-monitoring instruments, is that they are not truly point-monitoring devices but the wind speed measured is rather a weighted average of the line-of-sight velocity component over an extended spatial volume. The width of the weighting function along the beam is for pulsed systems mainly determined by the laser pulse length together with the sampling duration for a single Doppler spectrum, whereas for continuous-wave systems the focal depth of the laser beam determines the weighting width. Here, some recent results regarding the effect of this spatial volume averaging on turbulence measurements are presented. One common approach to obtain the whole wind vector is to perform a conical scan of the Lidar laser beam, which under the horizontal homogeneity assumption allows for the wind vector to be extracted. The wind vector measured is thus, in some sense, averaged over a substantial lateral area and time. However, temporal as well as spatial resolution of the wind field could be improved if instead three fully steerable Lidars were simultaneously measuring from three different locations around the air volume of interest. Based on this concept, a ground-based Doppler Lidar Windscanner facility capable of providing the wind vector in several hundred locations each second is currently under development within a Risø DTU project that aims at providing a useful research tool in the field of wind power meteorology for the decade ahead. A field campaign inter-comparison of the turbulence and the wind vector measured by a sonic anemometer and by three Lidars staring from three different directions towards the location of the sonic

  13. Conversion of magnetic field energy into kinetic energy in the solar wind

    NASA Technical Reports Server (NTRS)

    Whang, Y. C.

    1972-01-01

    The outflow of the solar magnetic field energy (the radial component of the Poynting vector) per steradian is inversely proportional to the solar wind velocity. It is a decreasing function of the heliocentric distance. When the magnetic field effect is included in the one-fluid model of the solar wind, the transformation of magnetic field energy into kinetic energy during the expansion process increases the solar wind velocity at 1 AU by 17 percent.

  14. Field Wind Tunnel Assessment of the Potential for Wind Transport of Soils at Clean Slate 1

    SciTech Connect

    Lancaster, Nicholas; Gillespie, David; Hokett, Sam; Metzger, Steve

    2005-02-01

    Field wind tunnel studies conducted in May, June, and November 1997 on the remediated area at Clean Slate 1 provide information on the resuspension of dust from untreated surfaces and those stabilized with the co-polymer "Agrilok". A total of 24 valid datasets were obtained and provide information on the total flux of dust in a "worst case" scenario. The test conducted indicate that the surfaces treated with Agrilok are resistant to erosion and resuspension of fine particles by wind action in all but extreme cases. Most of the material emitted by these surfaces is probably derived from resuspension of dust deposited by natural processes with a minor contribution from disturbance during remediation activities. The concentration of 239Pu in in emitted dust was very low. In combination with the low dust fluxes from the treated surfaces, this resulted in a low activity flux of 239Pu from these surfaces. The results of this study strongly suggest that the techniques for remediating these surfaces are effective in minimizing the flux of dust that may contain 239Pu .

  15. Wind-field modeling of nuclear accident consequences for Hong Kong

    SciTech Connect

    Yeung, M.R.; Lui, W.S.

    1997-06-01

    An efficient weighted interpolation technique is used to generate a time series of wind fields from the measurements of seven strategically located weather stations in Greater Hong Kong. This wind-field model, HKWIND, is integrated with the atmospheric dispersion/consequence model RADIS to form a complete off-site nuclear accident analysis package. A study is also performed that compares the calculational results of accident consequences with and without wind-field models. The inclusion of the wind-field model has a drastic effect on the puff trajectory and subsequently increases the frequencies of early fatality, early injuries, and latent cancers for Hong Kong.

  16. StenniSphere reopens after Hurricane Katrina

    NASA Technical Reports Server (NTRS)

    2006-01-01

    StenniSphere reopened Jan. 18, 2006, almost five months after Hurricane Katrina damaged the basement of the building that houses the visitor center. Thanks to the staff's careful preparations before the storm, no artifacts or exhibits were harmed.

  17. Characterization of the wind loads and flow fields around a gable-roof building model in tornado-like winds

    NASA Astrophysics Data System (ADS)

    Hu, Hui; Yang, Zifeng; Sarkar, Partha; Haan, Fred

    2011-09-01

    An experimental study was conducted to quantify the characteristics of a tornado-like vortex and to reveal the dynamics of the flow-structure interactions between a low-rise, gable-roof building model and swirling, turbulent tornado-like winds. The experimental work was conducted by using a large-scale tornado simulator located in the Aerospace Engineering Department of Iowa State University. In addition to measuring the pressure distributions and resultant wind loads acting on the building model, a digital Particle Image Velocimetry system was used to conduct detailed flow field measurements to quantify the evolution of the unsteady vortices and turbulent flow structures around the gable-roof building model in tornado-like winds. The effects of important parameters, such as the distance between the centers of the tornado-like vortex and the test model and the orientation angles of the building model related to the tornado-like vortex, on the evolutions of the wake vortices and turbulent flow structures around the gable-roof building model as well as the wind loads induced by the tornado-like vortex were assessed quantitatively. The detailed flow field measurements were correlated with the surface pressure and wind load measurements to elucidate the underlying physics to gain further insight into flow-structure interactions between the gable-roof building model and tornado-like winds in order to provide more accurate prediction of wind damage potential to built structures.

  18. Ocean wave effects on the retrieved wind field from the scatterometer

    NASA Astrophysics Data System (ADS)

    Ren, L.; Yang, J. S.; Zheng, G.

    2014-03-01

    The scatterometer is a kind of non-nadir real aperture radar (RAR), which can estimate the wind field of sea surface based on geophysical model function (GMF). GMF describes the empirical relation between the wind field and the sea surface roughness characterized by sigma0. The wind wave is generated from the local wind and the swell wave is independent of the one. Based on the multi-scale scattering model, both wind wave and swell wave will modulate the sea surface roughness. This paper tries to find out the wave effects on wind field retrieval from scatterometer in swell and wind wave by the synchronous scatterometer and buoy data. The wind field data used in this paper are collected from Metop's Advanced Scatterometer (ASCAT) and buoy of NDBC. The NDBC buoy also provides the synchronous significant wave height (swh) and peak wavelength. From these data, the sea states are divided into swell and wind wave. Then the wave effects on retrieval are analyzed along with the swh and peak wavelength in each sea states. Results show that swell wave has a serious effect on the wind field retrieval. When the swh is higher than 1.5 m or the peak wavelength is lower than 230 m, the retrievals have significant errors.

  19. Combined Experiment Phase 1. [Horizontal axis wind turbines: wind tunnel testing versus field testing

    SciTech Connect

    Butterfield, C.P.; Musial, W.P.; Simms, D.A.

    1992-10-01

    How does wind tunnel airfoil data differ from the airfoil performance on an operating horizontal axis wind turbine (HAWT) The National Renewable Energy laboratory has been conducting a comprehensive test program focused on answering this question and understanding the basic fluid mechanics of rotating HAWT stall aerodynamics. The basic approach was to instrument a wind rotor, using an airfoil that was well documented by wind tunnel tests, and measure operating pressure distributions on the rotating blade. Based an the integrated values of the pressure data, airfoil performance coefficients were obtained, and comparisons were made between the rotating data and the wind tunnel data. Care was taken to the aerodynamic and geometric differences between the rotating and the wind tunnel models. This is the first of two reports describing the Combined Experiment Program and its results. This Phase I report covers background information such as test setup and instrumentation. It also includes wind tunnel test results and roughness testing.

  20. Katrina Kinetics: The Physician Supply.

    PubMed

    Rigby, Perry Gardner; Paragi Gururaja, Ramnaryan

    2016-01-01

    In the aftermath of Hurricane Katrina 10 years ago, acute changes were recognized and reported; acute kinetic destruction and desperation. Physicians performed heroically, but after the flood and the closing of hospitals, most left at least briefly. The chronic recovery began with spirit, but was uncharted and unplanned with the recognition that individual decisions were a necessity. The documentation of physician numbers of practicing doctors, residents and fellows, from the AMA as related to geography, population, and other circumstances tells an additional story of renewal, more objectively without the hype. The fall and rise of the physician population occurred, and was and is remarkable in its consistency, smaller than expected variations. Its effect generated promise for continuous chronic conditions of recovery and positive change. PMID:27598896

  1. DRUG MARKET RECONSTITUTION AFTER HURRICANE KATRINA: LESSONS FOR LOCAL DRUG ABUSE CONTROL INITIATIVES

    PubMed Central

    Bennett, Alex S.; Golub, Andrew; Dunlap, Eloise

    2011-01-01

    Hurricane Katrina accomplished what no law enforcement initiative could ever achieve: It completely eradicated the New Orleans drug market. However, Katrina did little to eliminate the demand for drugs. This article documents the process of the drug market reconstitution that occurred 2005–2008 based on in-depth interviews and focus groups with predominately low-income drug users and sellers. Before Katrina, the drug market was largely characterized by socially-bonded participants involved with corporate style distribution. After Katrina, a violent freelance market emerged. The conclusion draws recommendations for law enforcement for dealing with drug markets after a major disaster. This article uses New Orleans as a case study to chart the process of drug market reconstitution following an extreme disaster, namely Hurricane Katrina. On August 29, 2005, Hurricane Katrina made landfall and engulfed the New Orleans area, overwhelming levees and causing extensive flooding and destruction across the city. The storm generated 30- to 40-foot waves, which demolished many cities and small towns in Southern Mississippi and Alabama and caused considerable wind damage further inland. Although the hurricane eye missed central New Orleans by about 30 miles, the wave action in Lake Pontchartrain caused several levees to break and flood most of eastern New Orleans, which was under sea level. The storm had an impact on practically all New Orleans residents and almost destroyed New Orleans (Cooper & Block, 2006; Levitt & Whitaker, 2009; Lee, 2006). Our research focused on the impact of this storm on the drug markets in New Orleans. Katrina destroyed the physical environment and organizational structure that sustained the drug trade, yet drug use and sales did not disappear. During and soon after the storm, improvised sales and distribution organizations provided a wide range of illicit drugs to users (see Dunlap, Johnson, Kotarba, & Fackler, 2009; Dunlap & Golub, 2010; Dunlap

  2. Spatial sampling of the thermospheric vertical wind field at auroral latitudes

    NASA Astrophysics Data System (ADS)

    Anderson, C.; Davies, T.; Conde, M.; Dyson, P.; Kosch, M. J.

    2011-06-01

    Results are presented from two nights of bistatic Doppler measurements of neutral thermospheric winds using Fabry-Perot spectrometers at Mawson and Davis stations in Antarctica. A scanning Doppler imager (SDI) at Mawson and a narrow-field Fabry-Perot spectrometer (FPS) at Davis have been used to estimate the vertical wind at three locations along the great circle joining the two stations, in addition to the vertical wind routinely observed above each station. These data were obtained from observations of the 630.0 nm airglow line of atomic oxygen, at a nominal altitude of 240 km. Low-resolution all-sky images produced by the Mawson SDI have been used to relate disturbances in the measured vertical wind field to auroral activity and divergence in the horizontal wind field. Correlated vertical wind responses were observed on a range of horizontal scales from ˜150 to 480 km. In general, the behavior of the vertical wind was in agreement with earlier studies, with strong upward winds observed poleward of the optical aurora and sustained, though weak, downward winds observed early in the night. The relation between vertical wind and horizontal divergence was seen to follow the general trend predicted by Burnside et al. (1981), whereby upward vertical winds were associated with positive divergence and vice versa; however, a scale height approximately 3-4 times greater than that modeled by NRLMSISE-00 was required to best fit the data using this relation.

  3. CFD wind tunnel test: Field velocity patterns of wind on a building with a refuge floor

    NASA Astrophysics Data System (ADS)

    Cheng, C. K.; Yuen, K. K.; Lam, K. M.; Lo, S. M.

    2005-10-01

    This paper reports a CFD wind tunnel study of wind patterns on a square-plan building with a refuge floor at its mid-height level. In this study, a technique of using calibrated power law equations of velocity and turbulent intensity applied as the boundary conditions in CFD wind tunnel test is being evaluated by the physical wind tunnel data obtained by the Principal Author with wind blowing perpendicularly on the building without a refuge floor. From the evaluated results, an optimised domain of flow required to produce qualitative agreement between the wind tunnel data and simulated results is proposed in this paper. Simulated results with the evaluated technique are validated by the wind tunnel data obtained by the Principal Author. The results contribute to an understanding of the fundamental behaviour of wind flow in a refuge floor when wind is blowing perpendicularly on the building. Moreover, the results reveal that the designed natural ventilation of a refuge floor may not perform desirably when the wind speed on the level is low. Under this situation, the refuge floor may become unsafe if smoke was dispersed in the leeward side of the building at a level immediately below the refuge floor.

  4. Observed wind and wave field structures from multi-sensor satellite measurements

    SciTech Connect

    Queffeulou, P.; Bentamy, A.

    1994-12-31

    Sea surface wind speed and wave data are presently available from various sensors in flight on several satellites. The wind speed and direction are available from the wind scatterometer of ERS-1. The wind speed can also be inferred from altimeters on board ERS-1 and TOPEX POSEIDON, and from the Special Microwave Imager on the satellites of the Defense Meteorological Space Program. These data are merged and used to investigate sea surface wind and wave field structure. One application study presently in progress, concerning the Mistral, is presented.

  5. Sediment from Hurricane Katrina: Potential to Produce Pulmonary Dysfunction in Mice

    PubMed Central

    Wang, Kai; You, Dahui; Balakrishna, Shrilatha; Ripple, Michael; Ahlert, Terry; Fahmy, Baher; Becnel, David; Daly, Melissa; Subra, Wilma; McElduff, James S.; Lomax, Larry G.; Troxclair, Dana; Cormier, Stephania A.

    2008-01-01

    On August 29, 2005, Hurricane Katrina made landfall along the Gulf Coast as a Category 3 hurricane. The associated storm surge and heavy rainfall resulted in major flooding throughout the New Orleans area. As the flood waters receded, thick sediment was left covering the ground and coating the interior of homes. This sediment was dispersed into the air and inhaled as dust by returning residents and workers. Our objective in this study was to evaluate the potential pulmonary effects associated with the respirable particulate matter (PM) derived from Hurricane Katrina (HK-PM) in mice. Samples of PM were collected from several locations along the Gulf Coast on September 30 and October 2, 2005 and had a mean aerodynamic diameter ranging from 3-5 μm). Chemical analysis and cytotoxicity assays were performed for all HK-PM samples. A few samples with varying levels of cytotoxicity were chosen for an acute inhalation exposure study. Airborne PM10 levels recorded in the New Orleans area post-Katrina were variable, ranging from 70 μg/m3 in Gentilly to 688 μg/m3 in Lakeview (residential areas). Mice exposed to one of these samples developed significant pulmonary inflammation and airways resistance and hyperresponsiveness to methacholine challenge. These studies demonstrate that dispersion of certain Katrina sediment samples through either natural (e.g., wind) or mechanical (e.g., vehicles) processes promotes airflow obstruction in mice. PMID:19079667

  6. Public health response to Hurricanes Katrina and Rita--United States, 2005.

    PubMed

    2006-03-10

    On August 29, 2005, Hurricane Katrina struck the U.S. Gulf Coast, the eye making landfall at Plaquemines Parish, Louisiana . The events that followed made Katrina the deadliest hurricane since 1928 and likely the costliest natural disaster on record in the United States. Devastating storm surge, strong winds, and heavy rains caused widespread destruction in Louisiana, Mississippi, Alabama, and Florida. Storm-induced breeches in the levee system surrounding New Orleans flooded 80% of the city. The disaster was compounded when Hurricane Rita made landfall 26 days later near the Texas-Louisiana border, forcing cessation of hurricane-response activities in New Orleans and evacuation of coastal regions of Louisiana and Texas. The economic and health consequences of Hurricanes Katrina and Rita extended beyond the Gulf region to affect states and communities throughout the United States. MMWR is highlighting the public health response to Hurricanes Katrina and Rita with two special issues. The first issue, published January 20, 2006, focused on public health activities in Louisiana. This second issue focuses on activities in other states directly or indirectly affected by the two hurricanes.

  7. Fields of Opportunity: Wind Machines Return to the Plains

    ERIC Educational Resources Information Center

    Sowers, Jacob

    2006-01-01

    The last two decades have seen a rebirth of wind machines on the rural landscape. In ironic fashion the wind's kinetic energy has grown in significance through its ability to generate commercial amounts of electricity, the commodity that a few generations earlier hastened the demise of the old Great Plains windmill. Yet the reemergence of wind…

  8. Examination of forced unsteady separated flow fields on a rotating wind turbine blade

    SciTech Connect

    Huyer, S. )

    1993-04-01

    The wind turbine industry faces many problems regarding the construction of efficient and predictable wind turbine machines. Steady state, two-dimensional wind tunnel data are generally used to predict aerodynamic loads on wind turbine blades. Preliminary experimental evidence indicates that some of the underlying fluid dynamic phenomena could be attributed to dynamic stall, or more specifically to generation of forced unsteady separated flow fields. A collaborative research effort between the University of Colorado and the National Renewable Energy Laboratory was conducted to systematically categorize the local and global effects of three- dimensional forced unsteady flow fields.

  9. Joint Offshore Wind Field Monitoring with Spaceborne SAR and Platform-Based Doppler LIDAR Measurements

    NASA Astrophysics Data System (ADS)

    Jacobsen, S.; Lehner, S.; Hieronimus, J.; Schneemann, J.; Kuhn, M.

    2015-04-01

    The increasing demand for renewable energy resources has promoted the construction of offshore wind farms e.g. in the North Sea. While the wind farm layout consists of an array of large turbines, the interrelation of wind turbine wakes with the remaining array is of substantial interest. The downstream spatial evolution of turbulent wind turbine wakes is very complex and depends on manifold parameters such as wind speed, wind direction and ambient atmospheric stability conditions. To complement and validate existing numerical models, corresponding observations are needed. While in-situ measurements with e.g. anemometers provide a time-series at the given location, the merits of ground-based and space- or airborne remote sensing techniques are indisputable in terms of spatial coverage. Active microwave devices, such as Scatterometer and Synthetic Aperture Radar (SAR), have proven their capabilities of providing sea surface wind measurements and particularly SAR images reveal wind variations at a high spatial resolution while retaining the large coverage area. Platform-based Doppler LiDAR can resolve wind fields with a high spatial coverage and repetition rates of seconds to minutes. In order to study the capabilities of both methods for the investigation of small scale wind field structures, we present a direct comparison of observations obtained by high resolution TerraSAR-X (TS-X) X-band SAR data and platform-based LiDAR devices at the North Sea wind farm alpha ventus. We furthermore compare the results with meteorological data from the COSMO-DE model run by the German Weather Service DWD. Our study indicates that the overall agreement between SAR and LiDAR wind fields is good and that under appropriate conditions small scale wind field variations compare significantly well.

  10. Appendix I1-2 to Wind HUI Initiative 1: Field Campaign Report

    SciTech Connect

    John Zack; Deborah Hanley; Dora Nakafuji

    2012-07-15

    This report is an appendix to the Hawaii WindHUI efforts to dev elop and operationalize short-term wind forecasting and wind ramp event forecasting capabilities. The report summarizes the WindNET field campaign deployment experiences and challenges. As part of the WindNET project on the Big Island of Hawaii, AWS Truepower (AWST) conducted a field campaign to assess the viability of deploying a network of monitoring systems to aid in local wind energy forecasting. The data provided at these monitoring locations, which were strategically placed around the Big Island of Hawaii based upon results from the Oahu Wind Integration and Transmission Study (OWITS) observational targeting study (Figure 1), provided predictive indicators for improving wind forecasts and developing responsive strategies for managing real-time, wind-related system events. The goal of the field campaign was to make measurements from a network of remote monitoring devices to improve 1- to 3-hour look ahead forecasts for wind facilities.

  11. Wintertime connections between extreme wind patterns in Spain and large-scale geopotential height field

    NASA Astrophysics Data System (ADS)

    Pascual, A.; Martín, M. L.; Valero, F.; Luna, M. Y.; Morata, A.

    2013-03-01

    The present study is focused on the study of the variability and the most significant wind speed patterns in Spain during the winter season analyzing as well connections between the wind speed field and the geopotential height at 1000 hPa over an Atlantic area. The daily wind speed variability is investigated by means of principal components using wind speed observations. Five main modes of variation, accounting 66% of the variance of the original data, have been identified, highlighting their differences in the Spanish wind speed behavior. Connections between the wind speeds and the large-scale atmospheric field were underlined by means of composite maps. Composite maps were built up to give an averaged atmospheric circulation associated with extreme wind speed variability in Spain. Moreover, the principal component analysis was also applied to the geopotential heights, providing relationships between the large-scale atmospheric modes and the observational local wind speeds. Such relationships are shown in terms of the cumulated frequency values of wind speed associated with the extreme scores of the obtained large-scale atmospheric modes, showing those large-scale atmospheric patterns more dominant in the wind field in Spain.

  12. Evaluation of wind fields used in Grand Canyon Visibility Transport Commission analyses.

    PubMed

    Green, M C; Pai, P; Ashbaugh, L; Farber, R J

    2000-05-01

    The Grand Canyon Visibility Transport Commission (GCVTC) was established by the U.S. Congress to assess the potential impacts of projected growth on atmospheric visibility at Grand Canyon National Park and to make recommendations to the U.S. Environmental Protection Agency on what measures could be taken to avoid such adverse impacts. A critical input to the assessment tool used by the commission was three-dimensional model-derived wind fields used to transport the emissions. This paper describes the evaluation of the wind fields used at various stages in the assessment. Wind fields evaluated included those obtained from the Colorado State University Regional Atmospheric Modeling System (RAMS), the National Meteorological Center's Nested Grid Model (NGM), and the National Oceanic and Atmospheric Administration's Atmospheric Transport and Dispersion (ATAD) trajectory model. The model-derived wind fields were evaluated at multiple vertical levels at several locations in the southwestern United States by determining differences between model predicted winds and winds that were measured using radiosonde and radar wind profiler data. Model-derived winds were also evaluated by determining the percent of time that they were within acceptable differences from measured winds. All models had difficulties, generally meeting the acceptable criteria for less than 50% of the predictions. The RAMS model had a persistent bias toward southwesterly winds at the expense of other directions, especially failing to represent channeling by north-south mountain ranges in the lower levels. The NGM model exhibited a substantial bias in the summer months by extending northwesterly winds in the eastern Pacific Ocean well inland, in contrast to the observed southwesterlies at inland locations. The simpler ATAD trajectory model performed somewhat better than the other models, probably because of its use of more upper air sites. The results of the evaluation indicated that these wind fields

  13. Deriving dynamics from GPS radio occultation: Three-dimensional wind fields for monitoring the climate

    PubMed Central

    Scherllin-Pirscher, Barbara; Steiner, Andrea Karin; Kirchengast, Gottfried

    2014-01-01

    Global Positioning System (GPS) radio occultation (RO) measurements are proven highly useful for observing the thermal structure of the troposphere and stratosphere. Here we use RO data for the first time to derive climatological wind fields from sampling error-corrected geopotential height fields on isobaric surfaces from about 800 hPa to 3 hPa. We find monthly mean RO geostrophic wind and gradient wind fields (2007 to 2012, about 500 km horizontal resolution, outside tropics) to clearly capture all main wind features, with differences to atmospheric analysis winds being, in general, smaller than 2 m/s. Larger differences (up to 10 m/s) occur close to the subtropical jet where RO winds underestimate actual winds. Such biases are caused by the geostrophic and gradient wind approximations, while RO retrieval errors introduce negligible effect. These results demonstrate that RO wind fields are of high quality and can provide new information on troposphere-stratosphere dynamics, for the benefit of monitoring the climate from weekly to decadal scales. PMID:26074640

  14. The variability of the surface wind field in the equatorial Pacific Ocean: Criteria for satellite measurements

    NASA Technical Reports Server (NTRS)

    Halpern, D.

    1984-01-01

    The natural variability of the equatorial Pacific surface wind field is described from long period surface wind measurements made at three sites along the equator (95 deg W, 109 deg 30 W, 152 deg 30 W). The data were obtained from surface buoys moored in the deep ocean far from islands or land, and provide criteria to adequately sample the tropical Pacific winds from satellites.

  15. SMART Wind Turbine Rotor: Design and Field Test

    SciTech Connect

    Berg, Jonathan C.; Resor, Brian R.; Paquette, Joshua A.; White, Jonathan R.

    2014-01-29

    This report documents the design, fabrication, and testing of the SMART Rotor. This work established hypothetical approaches for integrating active aerodynamic devices (AADs) into the wind turbine structure and controllers.

  16. Wind Loads on Flat Plate Photovoltaic Array Fields

    NASA Technical Reports Server (NTRS)

    Miller, R.; Zimmerman, D.

    1979-01-01

    The aerodynamic forces resulting from winds acting on flat plate photovoltaic arrays were investigated. Local pressure distributions and total aerodynamic forces on the arrays are shown. Design loads are presented to cover the conditions of array angles relative to the ground from 20 deg to 60 deg, variable array spacings, a ground clearance gap up to 1.2 m (4 ft) and array slant heights of 2.4 m (8 ft) and 4.8 m (16 ft). Several means of alleviating the wind loads on the arrays are detailed. The expected reduction of the steady state wind velocity with the use of fences as a load alleviation device are indicated to be in excess of a factor of three for some conditions. This yields steady state wind load reductions as much as a factor of ten compared to the load incurred if no fence is used to protect the arrays. This steady state wind load reduction is offset by the increase in turbulence due to the fence but still an overall load reduction of 2.5 can be realized. Other load alleviation devices suggested are the installation of air gaps in the arrays, blocking the flow under the arrays and rounding the edges of the array. A wind tunnel test plan to supplement the theoretical study and to evaluate the load alleviation devices is outlined.

  17. Signature of solar wind turbulence in the ground magnetic field and its relation to ion acceleration

    NASA Astrophysics Data System (ADS)

    Kronberg, Elena; Gilder, Stuart; Luo, Hao; Daly, Patrick; Grigorenko, Elena

    2016-04-01

    The effect of solar wind turbulence on the magnetospheric environment is still unclear. We show that the strength of the magnetic field variation measured by ground-based observations (INTERMAGNET) is associated with variations of the interplanetary magnetic field direction and the solar wind speed. The variation is strongest during the declining phase of the solar cycle and is associated with high speed streams and Alfvén waves in the solar wind. Using Cluster observations, we show that during the declining phase, the ions are effectively accelerated to energies above 100 keV in the plasma sheet. This implies that on long time scales, enhanced solar wind magnetic field fluctuations and wind speeds lead to favorable conditions for effective ion acceleration in the plasma sheet. The acceleration is associated with magnetic turbulence (ultra-low-frequency) in the plasma sheet.

  18. A simple method to estimate threshold friction velocity of wind erosion in the field

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nearly all wind erosion models require the specification of threshold friction velocity (TFV). Yet determining TFV of wind erosion in field conditions is difficult as it depends on both soil characteristics and distribution of vegetation or other roughness elements. While several reliable methods ha...

  19. Solar wind dynamic pressure and electric field as the main factors controlling Saturn's aurorae.

    PubMed

    Crary, F J; Clarke, J T; Dougherty, M K; Hanlon, P G; Hansen, K C; Steinberg, J T; Barraclough, B L; Coates, A J; Gérard, J-C; Grodent, D; Kurth, W S; Mitchell, D G; Rymer, A M; Young, D T

    2005-02-17

    The interaction of the solar wind with Earth's magnetosphere gives rise to the bright polar aurorae and to geomagnetic storms, but the relation between the solar wind and the dynamics of the outer planets' magnetospheres is poorly understood. Jupiter's magnetospheric dynamics and aurorae are dominated by processes internal to the jovian system, whereas Saturn's magnetosphere has generally been considered to have both internal and solar-wind-driven processes. This hypothesis, however, is tentative because of limited simultaneous solar wind and magnetospheric measurements. Here we report solar wind measurements, immediately upstream of Saturn, over a one-month period. When combined with simultaneous ultraviolet imaging we find that, unlike Jupiter, Saturn's aurorae respond strongly to solar wind conditions. But in contrast to Earth, the main controlling factor appears to be solar wind dynamic pressure and electric field, with the orientation of the interplanetary magnetic field playing a much more limited role. Saturn's magnetosphere is, therefore, strongly driven by the solar wind, but the solar wind conditions that drive it differ from those that drive the Earth's magnetosphere. PMID:15716946

  20. Solar wind dynamic pressure and electric field as the main factors controlling Saturn's aurorae.

    PubMed

    Crary, F J; Clarke, J T; Dougherty, M K; Hanlon, P G; Hansen, K C; Steinberg, J T; Barraclough, B L; Coates, A J; Gérard, J-C; Grodent, D; Kurth, W S; Mitchell, D G; Rymer, A M; Young, D T

    2005-02-17

    The interaction of the solar wind with Earth's magnetosphere gives rise to the bright polar aurorae and to geomagnetic storms, but the relation between the solar wind and the dynamics of the outer planets' magnetospheres is poorly understood. Jupiter's magnetospheric dynamics and aurorae are dominated by processes internal to the jovian system, whereas Saturn's magnetosphere has generally been considered to have both internal and solar-wind-driven processes. This hypothesis, however, is tentative because of limited simultaneous solar wind and magnetospheric measurements. Here we report solar wind measurements, immediately upstream of Saturn, over a one-month period. When combined with simultaneous ultraviolet imaging we find that, unlike Jupiter, Saturn's aurorae respond strongly to solar wind conditions. But in contrast to Earth, the main controlling factor appears to be solar wind dynamic pressure and electric field, with the orientation of the interplanetary magnetic field playing a much more limited role. Saturn's magnetosphere is, therefore, strongly driven by the solar wind, but the solar wind conditions that drive it differ from those that drive the Earth's magnetosphere.

  1. Coastal zone wind energy. Part II: Validation of the coastal zone wind power potential. A summary of the field experiment

    SciTech Connect

    Garstang, M.; Pielke, R.A.; Snow, J.W.

    1980-06-01

    Procedures have been developed to determine the wind power potential of the coastal region from Maine to Texas. The procedures are based upon a climatological analysis and a mesoscale numerical model. The results of this procedure are encouraging but need to be tested. In January to February 1980 a field measurement program was carried out over the Delmarva Peninsula centered on Wallops Island and extending into the Atlantic Ocean and Chesapeake Bay to provide an observational basis on which to test our wind assessment methods. The field experiment is described. Listings of the measurements made by aircraft, tethered balloon, rawinsonde kites, tower mounted anemometry and surface thermometry are given together with sample results. The analysis of these data and the comparison between them and the model predicted fields are presented.

  2. Regional Field Verification -- Operational Results from Four Small Wind Turbines in the Pacific Northwest: Preprint

    SciTech Connect

    Sinclair, K.; Raker, J.

    2006-08-01

    This paper describes four small wind turbines installed in the Pacific Northwest under DOE/NREL's Regional Field Verification Program between 2003 and 2004 and summarizes operational data from each site.

  3. In-field use of laser Doppler vibrometer on a wind turbine blade

    SciTech Connect

    Rumsey, M.; Hurtado, J.; Hansche, B.

    1998-12-31

    One of our primary goals was to determine how well a laser Doppler vibrometer (LDV) could measure the structural dynamic response of a wind turbine that was parked in the field. We performed a series of preliminary tests in the lab to determine the basic limitations of the LDV for this application. We then instrumented an installed parked horizontal axis wind turbine with accelerometers to determine the natural frequencies, damping, and mode shapes of the wind turbine and rotor as a baseline for the LDV and our other tests. We also wanted to determine if LDV modal information could be obtained from a naturally (wind) excited wind turbine. We compared concurrently obtained accelerometer and LDV data in an attempt to assess the quality of the LDV data. Our test results indicate the LDV can be successfully used in the field environment of an installed wind turbine, but with a few restrictions. We were successful in obtaining modal information from a naturally (wind) excited wind turbine in the field, but the data analysis requires a large number of averaged data sets to obtain reasonable results. An ultimate goal of this continuing project is to develop a technique that will monitor the health of a structure, detect damage, and hopefully predict an impending component failure.

  4. Regional Field Verification -- Case Study of Small Wind Turbines in the Pacific Northwest: Preprint

    SciTech Connect

    Sinclair, K.

    2005-05-01

    The U.S. Department of Energy/National Renewable Energy Laboratory's (DOE/NREL) Regional Field Verification (RFV) project supports industry needs for gaining initial field operation experience with small wind turbines and verify the performance, reliability, maintainability, and cost of small wind turbines in diverse applications. In addition, RFV aims to help expand opportunities for wind energy in new regions of the United States by tailoring projects to meet unique regional requirements and document and communicate the experience from these projects for the benefit of others in the wind power development community and rural utilities. Between August 2003 and August 2004, six turbines were installed at different host sites. At least one year of data has been collected from five of these sites. This paper describes DOE/NREL's RFV project, reviews some of the lessons learned with regards to small wind turbine installations, summarizes operations data from these sites, and provides preliminary BOS costs.

  5. Assessing Hurricane Katrina Damage to the Mississippi Gulf Coast Using IKONOS Imagery

    NASA Technical Reports Server (NTRS)

    Spruce, Joseph P.; McKellip, Rodney

    2007-01-01

    Hurricane Katrina hit southwestern Mississippi on August 29, 2005, at 10 a.m. CDT as a category 3 event with storm surges up to approximately 9 m and sustained winds of approximately 120 mph. The hurricane ravaged several coastal towns, destroying or severely damaging hundreds of homes. Hurricand Katrina deposited millions of tons of debris and caused severe damage to coastal forests. In response, several Federal agencies have been using a broad range of remotely sensed data (e.g., IKONOS) to aid damage assessment and disaster recovery efforts. This presentation discusses an effort to use IKONOS data for damage assessment, based on data collected over southwestern coastal Mississippi on September 2, 2005.

  6. Armature reaction effects on a high temperature superconducting field winding of an synchronous machine: experimental results

    NASA Astrophysics Data System (ADS)

    Mijatovic, Nenad; Jensen, Bogi Bech

    2014-05-01

    This paper presents experimental results from the Superwind laboratory setup. Particular focus in the paper has been placed on describing and quantifying the influence of armature reaction on performance of the HTS filed winding. Presented experimental results have confirmed the HTS field winding sensitivity to both armature reaction intensity and angular position with respect to the HTS coils. Furthermore, the characterization of the HTS field winding has been correlated to the electromagnetic torque of the machine where the maximal Ic reduction of 21% has been observed for the maximum torque.

  7. Aeolian Dune Deformation in a Multi-Directional Wind Regime, White Sands Dune Field, New Mexico

    NASA Astrophysics Data System (ADS)

    Pedersen, A.; Kocurek, G.

    2013-12-01

    Aeolian dunes commonly exist in a multi-directional wind regime. With each constructive wind event, dunes both migrate and deform as a function of the incidence angle of the primary wind to the local brinkline orientation. Can dune shape after many wind events be predicted from the resultant of these wind events? This question was addressed for sinuous crescentic dunes at the White Sands Dune Field, New Mexico, using: (1) a record of wind events from nearby Holloman AFB, and (2) a time-series of LiDAR-derived digital elevation models (DEMs) in which changes in dune shape can be accurately measured. From June 2007 to June 2010, 1,590 wind events occurred in which wind velocity was above the threshold of 18.66 m/s. Based upon the sand-transporting capacity of each wind event, the rose diagram for the overall wind regime shows three modes: (1) a dominant mode from the SW that occurred throughout the year but was most common during the spring, (2) a secondary mode from the N-NE during winter during the passage of frontal weather systems during the summer, and (3) a tertiary mode from the S-SE that occurred primarily during the summer months. From brinkline tracing and difference maps made from DEMs for June 2007, June 2008, January 2009, September 2009, and June 2010, the impact of each component of the wind regime upon dune morphology is evident. Winds from the SW cause dune migration to the NE, and dune crestlines are oriented nearly perpendicular to this wind direction. N-NE winds cause along-crest crabbing of dune sinuosity, accompanied by scour along the northern flank of convex-downwind lee-face segments. S-SE winds cause local crestal reversal and scour of the lee face. Idealized dune cross-strata can be constructed based upon the impact of each wind event. However, beginning with an initial dune shape, subsequent dune shapes in the DEM time-series cannot be predicted using the resultant for the period and its incidence angle with the initial brinkline

  8. SSC marks anniversary of Hurricane Katrina

    NASA Technical Reports Server (NTRS)

    2006-01-01

    At the Hurricane Katrina observance held Aug. 29 in the StenniSphere auditorium, Stennis Space Center Deputy Director David Throckmorton (left) and RAdm. Timothy McGee, Commander, Naval Meteorology and Oceanography Command, unveil a plaque dedicated to SSC employees.

  9. Real-Time Teaching: Lessons from Katrina

    ERIC Educational Resources Information Center

    Phillips, Antoinette S.; Phillips, Carl R.

    2008-01-01

    Professors strive constantly to find ways for students to apply what they are learning in the classroom, thereby reinforcing principles being taught and increasing student interest and involvement in the learning process. Hurricane Katrina's devastating impact on the Gulf Coast had wide-ranging consequences. As a result, many individuals…

  10. Katrina Exposes Our Schools' Shameful Inequality

    ERIC Educational Resources Information Center

    Hardy, Lawrence

    2006-01-01

    In this article, the author talks about the disaster in the United States that reignited a debate about poverty and the responsibility of government--and government schools--that had never really gone away in the first place. Hurricane Katrina was one of the biggest natural disasters in the U.S. that swept through four states, killed more than…

  11. Revisiting the Gulf Coast after Katrina

    ERIC Educational Resources Information Center

    Principal, 2009

    2009-01-01

    In August 2005, the world witnessed one of the most destructive natural disasters on America's mainland. Hurricane Katrina, followed a month later by Hurricane Rita, brought more than broken levees, flooded streets and homes, and destroyed businesses. It caused changes in the dynamics and the demographic and cultural makeup of the region. One of…

  12. Katrina Effect on Mathematics Achievement in Mississippi

    ERIC Educational Resources Information Center

    Lamb, John; Lewis, Mark; Gross, Sarah

    2013-01-01

    Hurricane Katrina caused severe physical damage to the Gulf Coast states of Louisiana, Mississippi, and Alabama. Homes and businesses were destroyed. Natural habitats were annihilated, and many Americans were displaced for days, weeks, and even years. This study investigated the within-subject effects and contrasts of poverty, rurality, and…

  13. The economics and ethics of Hurricane Katrina.

    PubMed

    Rockwell, Llewellyn H; Block, Walter E

    2010-01-01

    How might free enterprise have dealt with Hurricane Katrina and her aftermath. This article probes this question at increasing levels of radicalization, starting with the privatization of several government “services” and ending with the privatization of all of them.

  14. Hurricane Katrina. The disaster after the disaster.

    PubMed

    Colias, Mike

    2005-10-01

    More than a decade after Hurricane Andrew devastated much of South Florida and a year after a series of killer storms battered the state, hospitals there offer stark lessons--as well as inspiration and hope--for their counterparts reeling from Hurricane Katrina.

  15. Schooling the Forgotten Kids of Hurricane Katrina

    ERIC Educational Resources Information Center

    Cook, Glenn

    2006-01-01

    In this article, the author talks about students being taking in public schools in Houston and Dallas, as well as other states, after evacuating from New Orleans which was struck by Hurricane Katrina and Hurricane Rita. For students displaced by the storm, mobility is as constant as stability is elusive. Already traumatized and faced with the loss…

  16. Educators Reach out to Katrina Victims

    ERIC Educational Resources Information Center

    Hardy, Lawrence

    2006-01-01

    The emotional trauma of recent events may never go away. A million people were uprooted by Hurricane Katrina, including an estimated 372,000 children of school age. Three weeks later, Hurricane Rita slammed into the Texas-Louisiana coastline, forcing thousands more to evacuate. Acute symptoms of trauma range from confusion, nightmares, and…

  17. Spatial-temporal analysis of coherent offshore wind field structures measured by scanning Doppler-lidar

    NASA Astrophysics Data System (ADS)

    Valldecabres, L.; Friedrichs, W.; von Bremen, L.; Kühn, M.

    2016-09-01

    An analysis of the spatial and temporal power fluctuations of a simplified wind farm model is conducted on four offshore wind fields data sets, two from lidar measurements and two from LES under unstable and neutral atmospheric conditions. The integral length scales of the horizontal wind speed computed in the streamwise and the cross-stream direction revealed the elongation of the structures in the direction of the mean flow. To analyse the effect of the structures on the power output of a wind turbine, the aggregated equivalent power of two wind turbines with different turbine spacing in the streamwise and cross-stream direction is analysed at different time scales under 10 minutes. The fact of considering the summation of the power of two wind turbines smooths out the fluctuations of the power output of a single wind turbine. This effect, which is stronger with increasing spacing between turbines, can be seen in the aggregation of the power of two wind turbines in the streamwise direction. Due to the anti-correlation of the coherent structures in the cross-stream direction, this smoothing effect is stronger when the aggregated power is computed with two wind turbines aligned orthogonally to the mean flow direction.

  18. A solar wind-based model of geomagnetic field fluctuations at a mid-latitude station

    NASA Astrophysics Data System (ADS)

    Lotz, S. I.; Cilliers, P. J.

    2015-01-01

    Anomalous quasi-DC currents known as geomagnetically induced currents (GIC), produced in electric power network infrastructure during geomagnetic storms, pose a risk to reliable power transmission and network integrity. The prediction of a geomagnetic field-derived proxy to GIC provides an attractive mitigation technique that does not require changes to network hardware. In this paper we present the development of two artificial neural network based models tasked with predicting variations in the X (northward) and Y (eastward) components of the geomagnetic field at Hermanus, South Africa, with only solar wind plasma and interplanetary magnetic field (IMF) parameters as input. The models are developed by iteratively selecting the best set of solar wind parameters to predict the fluctuations in X and Y. To predict the variation in X, IMF magnitude, solar wind speed, fluctuation in solar wind proton density and a IMF-BZ derived parameter are selected. To predict the variation in Y, IMF-BZ , solar wind speed, and fluctuation in IMF magnitude are selected. The difference between the sets of selected input parameters are explained by the dependence of eastward perturbations in geomagnetic field at middle latitudes on field aligned currents. Model performance is evaluated during three storms in 2012. The onset and main phases of storms are fairly accurately predicted, but in cases where prolonged southward IMF coincides with solar wind parameters that are slowly varying the model fails to predict the observed fluctuations.

  19. Interplanetary Magnetic Field Power Spectrum Variations in the Inner Heliosphere: A Wind and MESSENGER Study

    NASA Technical Reports Server (NTRS)

    Szabo, Adam; Koval, A.

    2011-01-01

    The newly reprocessed high time resolution (11/22 vectors/sec) Wind mission interplanetary magnetic field data and the similar observations made by the MESSENGER spacecraft in the inner heliosphere affords an opportunity to compare magnetic field power spectral density variations as a function of radial distance from the Sun under different solar wind conditions. In the reprocessed Wind Magnetic Field Investigation (MFI) data, the spin tone and its harmonics are greatly reduced that allows the meaningful fitting of power spectra to the approx.2 Hz limit above which digitization noise becomes apparent. The powe'r spectral density is computed and the spectral index is fitted for the MHD and ion inertial regime separately along with the break point between the two for various solar wind conditions. Wind and MESSENGER magnetic fluctuations are compared for times when the two spacecraft are close to radial and Parker field alignment. The functional dependence of the ion inertial spectral index and break point on solar wind plasma and magnetic field conditions will be discussed.

  20. Wind turbine blade aerodynamics: The analysis of field test data

    SciTech Connect

    Luttges, M.W.; Miller, M.S.; Robinson, M.C.; Shipley, D.E.; Young, T.S.

    1994-08-01

    Data obtained from the National Renewable Energy Laboratory site test of a wind turbine (The Combined Experiment) was analyzed specifically to capture information regarding the aerodynamic loading experienced by the machine rotor blades. The inflow conditions were shown to be extremely variable. These inflows yielded three different operational regimes about the blades. Each regime produced very different aerodynamic loading conditions. Two of these regimes could not have been readily predicted from wind tunnel data. These conditions are being subjected to further analyses to provide new guidelines for both designers and operators. The roles of unsteady aerodynamics effects are highlighted since periods of dynamic stall were shown to be associated with brief episodes of high aerodynamic forces.

  1. Meteorological field measurements at potential and actual wind turbine sites

    SciTech Connect

    Renne, D.S.; Sandusky, W.F.; Hadley, D.L.

    1982-09-01

    An overview of experiences gained in a meteorological measurement program conducted at a number of locations around the United States for the purpose of site evaluation for wind energy utilization is provided. The evolution of the measurement program from its inception in 1976 to the present day is discussed. Some of the major accomplishments and areas for improvement are outlined. Some conclusions on research using data from this program are presented.

  2. Field Calibration of Wind Direction Sensor to the True North and Its Application to the Daegwanryung Wind Turbine Test Sites

    PubMed Central

    Lee, Jeong Wan

    2008-01-01

    This paper proposes a field calibration technique for aligning a wind direction sensor to the true north. The proposed technique uses the synchronized measurements of captured images by a camera, and the output voltage of a wind direction sensor. The true wind direction was evaluated through image processing techniques using the captured picture of the sensor with the least square sense. Then, the evaluated true value was compared with the measured output voltage of the sensor. This technique solves the discordance problem of the wind direction sensor in the process of installing meteorological mast. For this proposed technique, some uncertainty analyses are presented and the calibration accuracy is discussed. Finally, the proposed technique was applied to the real meteorological mast at the Daegwanryung test site, and the statistical analysis of the experimental testing estimated the values of stable misalignment and uncertainty level. In a strict sense, it is confirmed that the error range of the misalignment from the exact north could be expected to decrease within the credibility level.

  3. Spatial interpolation of wind fields in a stably stratified atmospheric boundary layer using OpenFOAM

    NASA Astrophysics Data System (ADS)

    Sauter, Tobias; Obleitner, Friedrich

    2014-05-01

    The knowledge of the spatial distribution of meteorological fields in complex terrain is required for a large number of meteorological and glaciological applications. Unfortunately, in most cases the spatial distribution of observations is sparse, and consequently insufficient to reliably estimate the wind field by common interpolation schemes. The synergetic relationship between the complex terrain and local wind systems, can lead to intense gap flows, channeling effects, katabatic flows and even flow blocking events. In order to take these effects into account, the computation of the three-dimensional flow pattern is necessary. The purpose of the current study is to develop and evaluate the performance of a two-step wind interpolation scheme for stably stratified flows. In a first step, a initial wind field is estimated from in-situ observations and radio-sounding measurements. In the second step, a buoyancy-driven flow solver is used to account for the kinematic effects of the terrain, slope flows and blocking effects. The solver is then initialized by the prior estimated initial wind fields. The steady-state incompressible solver is developed using the open source computational fluid dynamic software OpenFOAM. The proposed approach was applied and evaluated at the Kongsvegen glacier in Svalbard for the summer period 2011. Dynamical and thermodynamical effects, such as katabatic winds, lee and gap flows were well represented. The results show promising potential for further scientific investigations.

  4. Effects of screens set characteristics on the flow field in a wind tunnel

    NASA Astrophysics Data System (ADS)

    Santos, A. M.; Souza, D. B.; Costa, F. O.; Farias, M. H.; Massari, P. de L.; Araújo, S.; Zanirath, Y. B.

    2016-07-01

    Wind tunnels have broad range of applications, and although there are common elements among the different types of tunnels, the layout and configuration of each facility will depend on its particular purpose. The flow conditioners section is a common component for all tunnels, and frequently contains flow straighteners and screens [1]. The role of screens is to minimize non uniformities or turbulence level on the flow field. In this work, the development and characteristics of the vertical velocity profile along an atmospheric wind tunnel length were evaluated. By using such data as initial reference, the effects, on the flow, when screens set is inserted on it were analyzed, in order to identify which changes could be done in the wind tunnel configuration to improve the characteristics of the flow field. Such atmospheric wind tunnel is a facility which belongs to the Brazilian National Metrology Institute INMETRO.

  5. Plasma-field Coupling at Small Length Scales in Solar Wind Near 1 AU

    NASA Astrophysics Data System (ADS)

    Livadiotis, G.; Desai, M. I.

    2016-10-01

    In collisionless plasmas such as the solar wind, the coupling between plasma constituents and the embedded magnetic field occurs on various temporal and spatial scales, and is primarily responsible for the transfer of energy between waves and particles. Recently, it was shown that the transfer of energy between solar wind plasma particles and waves is governed by a new and unique relationship: the ratio between the magnetosonic energy and the plasma frequency is constant, E ms/ω pl ˜ ℏ*. This paper examines the variability and substantial departure of this ratio from ℏ* observed at ˜1 au, which is caused by a dispersion of fast magnetosonic (FMS) waves. In contrast to the efficiently transferred energy in the fast solar wind, the lower efficiency of the slow solar wind can be caused by this dispersion, whose relation and characteristics are derived and studied. In summary, we show that (i) the ratio E ms/ω pl transitions continuously from the slow to the fast solar wind, tending toward the constant ℏ* (ii) the transition is more efficient for larger thermal, Alfvén, or FMS speeds; (iii) the fast solar wind is almost dispersionless, characterized by quasi-constant values of the FMS speed, while the slow wind is subject to dispersion that is less effective for larger wind or magnetosonic speeds; and (iv) the constant ℏ* is estimated with the best known precision, ℏ* ≈ (1.160 ± 0.083) × 10-22 Js.

  6. 8000 Ways to Model a Vortex: A Review of Hindcast Wind Field Methodologies

    NASA Astrophysics Data System (ADS)

    Sweeney, J.

    2014-12-01

    Hindcasts of cyclonic wind fields are crucial for extreme analysis in the oil and gas industry. Recent scientific developments have increased the number of parameterization options for tropical cyclone vortices, leading to well over 8000 permutations of model choices. Which is best? Also problematic is how best to blend modelled vortex winds into a global wind model (such as the Climate Forecast System Reanalysis (CFSR)) in order to resolve tropical cyclones to sufficient detail for wave modelling. Standard blending schemes can leave a 'moat' between the vortex and the CFSR circulation (see Figure 1 from TC Olivia 1996). Using a 35-year track database from the Australian Bureau of Meteorology, this study assesses model configurations and blending schemes against the most extensive measured meteorological dataset in the north-east Indian Ocean (largely commercial-in-confidence). The Holland profile models of 1980 and 2008 are two starting points, with other options examined for radius to maximum wind calculations, pressure-wind relationships, averaging periods, atmospheric profiles, gust factors, and asymmetry methods. Once a vortex is modelled, the winds are then fitted to the radius of gales and blended into the CFSR before further verification. Initial results support recent theoretical developments by Hu et al (2012), with additional results that call for a new asymmetry method and the separation of pressure and wind field modelling.

  7. Interplanetary and Interstellar Dust Observed by the Wind/WAVES Electric Field Instrument

    NASA Technical Reports Server (NTRS)

    Malaspina, David; Horanyi, M.; Zaslavsky, A.; Goetz, K.; Wilson, L. B., III; Kersten, K.

    2014-01-01

    Observations of hypervelocity dust particles impacting the Wind spacecraft are reported here for the first time using data from the WindWAVES electric field instrument. A unique combination of rotating spacecraft, amplitude-triggered high-cadence waveform collection, and electric field antenna configuration allow the first direct determination of dust impact direction by any spacecraft using electric field data. Dust flux and impact direction data indicate that the observed dust is approximately micron-sized with both interplanetary and interstellar populations. Nanometer radius dust is not detected by Wind during times when nanometer dust is observed on the STEREO spacecraft and both spacecraft are in close proximity. Determined impact directions suggest that interplanetary dust detected by electric field instruments at 1 AU is dominated by particles on bound trajectories crossing Earths orbit, rather than dust with hyperbolic orbits.

  8. ENHANCED DISSIPATION RATE OF MAGNETIC FIELD IN STRIPED PULSAR WINDS BY THE EFFECT OF TURBULENCE

    SciTech Connect

    Takamoto, Makoto; Inoue, Tsuyoshi; Inutsuka, Shu-ichiro E-mail: inouety@phys.aoyama.ac.jp

    2012-08-10

    In this paper, we report on turbulent acceleration of the dissipation of the magnetic field in the post-shock region of a Poynting flux-dominated flow, such as the Crab pulsar wind nebula. We have performed two-dimensional resistive relativistic magnetohydrodynamics simulations of subsonic turbulence driven by the Richtmyer-Meshkov instability at the shock fronts of the Poynting flux-dominated flows in pulsar winds. We find that turbulence stretches current sheets which substantially enhances the dissipation of the magnetic field, and that most of the initial magnetic field energy is dissipated within a few eddy-turnover times. We also develop a simple analytical model for turbulent dissipation of the magnetic field that agrees well with our simulations. The analytical model indicates that the dissipation rate does not depend on resistivity even in the small resistivity limit. Our findings can possibly alleviate the {sigma}-problem in the Crab pulsar wind nebulae.

  9. Sensitivity of calculated odd nitrogen distributions to the diabatic wind fields

    NASA Technical Reports Server (NTRS)

    Boughner, R. E.; Callis, L. B., Jr.; Natarajan, M.

    1991-01-01

    This paper compares atmospheric total odd nitrogen and ozone computed with two different advective wind fields, one using climatological averages of ozone and temperature to obtain monthly averaged horizontal and vertical winds and the other using measurements from the LIMS instrument. Calculations using the former data show stronger poleward and downward motion in the winter season compared to those using the LIMS data. This leads to NO(y) mixing ratios in the lower stratosphere that are about 20 percent larger in the polar regions of both hemispheres and about 40 percent higher in the equatorial region for climatological transport fields compared to those derived from LIMS data. Consequently, the NO(y) distributions calculated with the LIMS advective field show worse agreement with the NO(y) values inferred from the LIMS measurements than similar results obtained with the climatological wind field.

  10. What determines the direction of minimum variance of the magnetic field fluctuations in the solar wind?

    NASA Technical Reports Server (NTRS)

    Grappin, R.; Velli, M.

    1995-01-01

    The solar wind is not an isotropic medium; two symmetry axis are provided, first the radial direction (because the mean wind is radial) and second the spiral direction of the mean magnetic field, which depends on heliocentric distance. Observations show very different anisotropy directions, depending on the frequency waveband; while the large-scale velocity fluctuations are essentially radial, the smaller scale magnetic field fluctuations are mostly perpendicular to the mean field direction, which is not the expected linear (WkB) result. We attempt to explain how these properties are related, with the help of numerical simulations.

  11. Global disturbance of the transient magnetic field associated with thermospheric storm winds on March 23, 1979

    SciTech Connect

    Fambitakoye, O. ); Menvielle, M. ); Mazaudier, C. Centre de Recherche sur la Physique de l'Environnement, Saint Maur des Fosses )

    1990-09-01

    During large magnetic storms, wind disturbances produces by auroral phenomena can affect the whole thermospheric circulation and associated ionospheric dynamo currents for many hours after the end of the storm. This paper presents a morphological analysis of the ground magnetic field disturbance related to the storm winds observed on March 23, 1979, the day after the Coordinated Data Analysis Workshop (CDAW) 6 events. The disturbance in the magnetic field variations is observed on a planetary scale, and its pattern does not correspond to that of the regular field variations related to the undisturbed atmospheric dynamo.

  12. Ion exchange with the solar wind for planets with negligible intrinsic magnetic fields

    NASA Technical Reports Server (NTRS)

    Nisbet, J. S.

    1979-01-01

    The exchange of ions between the ionosphere of a planet with negligible intrinsic magnetic field, and the solar wind is examined. It is suggested that a balance exists between the outflow of ionospheric ions at the plasmapause and ions from the solar wind in a restricted region close to the subsolar point. This results in a current system towards the subsolar point on the surface of the ionopause and a toroidal magnetic field. Simple calculations are made of the current and field configuration that might result from the system for conditions similar to those encountered on the Viking 1 and 2 transits of the Mars ionosphere.

  13. Impact of ocean warm layer thickness on the intensity of hurricane Katrina in a regional coupled model

    NASA Astrophysics Data System (ADS)

    Seo, Hyodae; Xie, Shang-Ping

    2013-10-01

    The effect of pre-storm subsurface thermal structure on the intensity of hurricane Katrina (2005) is examined using a regional coupled model. The Estimating Circulation and Climate of Ocean (ECCO) ocean state estimate is used to initialize the ocean component of the coupled model, and the source of deficiencies in the simulation of Katrina intensity is investigated in relation to the initial depth of 26 °C isotherm (D26). The model underestimates the intensity of Katrina partly due to shallow D26 in ECCO. Sensitivity tests with various ECCO initial fields indicate that the correct relationship between intensity and D26 cannot be derived because D26 variability is underestimated in ECCO. A series of idealized experiments is carried out by modifying initial ECCO D26 to match the observed range. A more reasonable relationship between Katrina’s intensity and pre-storm D26 emerges: the intensity is much more sensitive to D26 than to sea surface temperature (SST). Ocean mixed layer process plays a critical role in modulating inner-core SSTs when D26 is deep, reducing mixed layer cooling and lowering the center pressure of the Katrina. Our result lends strong support to the notion that accurate initialization of pre-storm subsurface thermal structure in prediction models is critical for a skillful forecast of intensity of Katrina and likely other intense storms.

  14. Probabilistic Path Planning of Montgolfier Balloons in Strong, Uncertain Wind Fields

    NASA Technical Reports Server (NTRS)

    Wolf, Michael; Blackmore, James C.; Kuwata, Yoshiaki

    2011-01-01

    Lighter-than-air vehicles such as hot-air balloons have been proposed for exploring Saturn s moon Titan, as well as other bodies with significant atmospheres. For these vehicles to navigate effectively, it is critical to incorporate the effects of surrounding wind fields, especially as these winds will likely be strong relative to the control authority of the vehicle. Predictive models of these wind fields are available, and previous research has considered problems of planning paths subject to these predicted forces. However, such previous work has considered the wind fields as known a priori, whereas in practical applications, the actual wind vector field is not known exactly and may deviate significantly from the wind velocities estimated by the model. A probabilistic 3D path-planning algorithm was developed for balloons to use uncertain wind models to generate time-efficient paths. The nominal goal of the algorithm is to determine what altitude and what horizontal actuation, if any is available on the vehicle, to use to reach a particular goal location in the least expected time, utilizing advantageous winds. The solution also enables one to quickly evaluate the expected time-to-goal from any other location and to avoid regions of large uncertainty. This method is designed for balloons in wind fields but may be generalized for any buoyant vehicle operating in a vector field. To prepare the planning problem, the uncertainty in the wind field is modeled. Then, the problem of reaching a particular goal location is formulated as a Markov decision process (MDP) using a discretized space approach. Solving the MDP provides a policy of what actuation option (how much buoyancy change and, if applicable, horizontal actuation) should be selected at any given location to minimize the expected time-to-goal. The results provide expected time-to-goal values from any given location on the globe in addition to the action policy. This stochastic approach can also provide

  15. Flooding in the Aftermath of Hurricane Katrina

    NASA Technical Reports Server (NTRS)

    2005-01-01

    These views of the Louisiana and Mississippi regions were acquired before and one day after Katrina made landfall along the Gulf of Mexico coast, and highlight many of the changes to the rivers and vegetation that occurred between the two views. The images were acquired by NASA's Multi-angle Imaging SpectroRadiometer (MISR) on August 14 and August 30, 2005. These multiangular, multispectral false-color composites were created using red band data from MISR's 46o backward and forward-viewing cameras, and near-infrared data from MISR's nadir camera. Such a display causes water bodies and inundated soil to appear in blue and purple hues, and highly vegetated areas to appear bright green. The scene differentiation is a result of both spectral effects (living vegetation is highly reflective at near-infrared wavelengths whereas water is absorbing) and of angular effects (wet surfaces preferentially forward scatter sunlight). The two images were processed identically and extend from the regions of Greenville, Mississippi (upper left) to Mobile Bay, Alabama (lower right).

    There are numerous rivers along the Mississippi coast that were not apparent in the pre-Katrina image; the most dramatic of these is a new inlet in the Pascagoula River that was not apparent before Katrina. The post-Katrina flooding along the edges of Lake Pontchartrain and the city of New Orleans is also apparent. In addition, the agricultural lands along the Mississippi floodplain in the upper left exhibit stronger near-infrared brightness before Katrina. After Katrina, many of these agricultural areas exhibit a stronger signal to MISR's oblique cameras, indicating the presence of inundated soil throughout the floodplain. Note that clouds appear in a different spot for each view angle due to a parallax effect resulting from their height above the surface.

    The Multi-angle Imaging SpectroRadiometer observes the daylit Earth continuously, viewing the entire globe between 82o north and 82o

  16. Environmental impact of Hurricane Katrina on Lake Pontchartrain: Chapter 7G in Science and the storms-the USGS response to the hurricanes of 2005

    USGS Publications Warehouse

    Heitmuller, Thomas; Perez, Brian C.

    2007-01-01

    Hurricane Katrina slammed the Louisiana-Mississippi Gulf Coast with 135-mi/hour (217-km/hour) winds and up to a 30-ft (9-m) storm surge. Lake Pontchartrain was further subjected to environmental threat by way of the millions of gallons of contaminated flood water that were pumped daily from the city of New Orleans into the lake.

  17. Field Testing: Independent, Accredited Testing and Validation for the Wind Industry (Fact Sheet)

    SciTech Connect

    Not Available

    2011-11-01

    This fact sheet describes the field testing capabilities at the National Wind Technology Center (NWTC). NREL's specialized facilities and personnel at the NWTC provide the U.S. wind industry with scientific and engineering support that has proven critical to the development of wind energy for U.S. energy needs. The NWTC's specialized field-testing capabilities have evolved over 30 years of continuous support by the U.S. Department of Energy Wind and Hydropower Technologies Program and long standing industry partnerships. The NWTC provides wind industry manufacturers, developers, and operators with turbine and component testing all in one convenient location. Although industry utilizes sophisticated modeling tools to design and optimize turbine configurations, there are always limitations in modeling capabilities, and testing is a necessity to ensure performance and reliability. Designs require validation and testing is the only way to determine if there are flaws. Prototype testing is especially important in capturing manufacturing flaws that might require fleet-wide retrofits. The NWTC works with its industry partners to verify the performance and reliability of wind turbines that range in size from 400 Watts to 3 megawatts. Engineers conduct tests on components and full-scale turbines in laboratory environments and in the field. Test data produced from these tests can be used to validate turbine design codes and simulations that further advance turbine designs.

  18. Solar wind interaction effects on the magnetic fields around Mars: Consequences for interplanetary and crustal field measurements

    NASA Astrophysics Data System (ADS)

    Luhmann, J. G.; Ma, Y.-J.; Brain, D. A.; Ulusen, D.; Lillis, R. J.; Halekas, J. S.; Espley, J. R.

    2015-11-01

    The first unambiguous detections of the crustal remanent magnetic fields of Mars were obtained by Mars Global Surveyor (MGS) during its initial orbits around Mars, which probed altitudes to within ∼110 km of the surface. However, the majority of its measurements were carried out around 400 km altitude, fixed 2 a.m. to 2 p.m. local time, mapping orbit. While the general character and planetary origins of the localized crustal fields were clearly revealed by the mapping survey data, their effects on the solar wind interaction could not be investigated in much detail because of the limited mapping orbit sampling. Previous analyses (Brain et al., 2006) of the field measurements on the dayside nevertheless provided an idea of the extent to which the interaction of the solar wind and planetary fields leads to non-ideal field draping at the mapping altitude. In this study we use numerical simulations of the global solar wind interaction with Mars as an aid to interpreting that observed non-ideal behavior. In addition, motivated by models for different interplanetary field orientations, we investigate the effects of induced and reconnected (planetary and external) fields on the Martian field's properties derived at the MGS mapping orbit altitude. The results suggest that inference of the planetary low order moments is compromised by their influence. In particular, the intrinsic dipole contribution may differ from that in the current models because the induced component is so dominant.

  19. Hurricane Katrina-induced forest damage in relation to ecological factors at landscape scale.

    PubMed

    Wang, Fugui; Xu, Y Jun

    2009-09-01

    Forest stand stability to strong winds such as hurricanes has been found to be associated with a number of forest, soil and topography factors. In this study, through applying geographic information system (GIS) and logit regression, we assessed effects of forest characteristics and site conditions on pattern, severity and probability of Hurricane Katrina disturbance to forests in the Lower Pearl River Valley, USA. The factors included forest type, forest coverage, stand density, soil great group, elevation, slope, aspect, and stream buffer zone. Results showed that Hurricane Katrina damaged 60% of the total forested land in the region. The distribution and intensity of the hurricane disturbance varied across the landscape, with the bottomland hardwood forests on river floodplains most severely affected. All these factors had a variety of effects on vulnerability of the forests to the hurricane disturbance and thereby spatial patterns of the disturbance. Soil groups and stand factors including forest types, forest coverage and stand density contributed to 85% of accuracy in modeling the probability of the hurricane disturbance to forests in this region. Besides assessment of Katrina's damage, this study elucidates the great usefulness of remote sensing and GIS techniques combined with statistics modeling in assessment of large-scale risks of hurricane damage to coastal forests.

  20. Energy-modeled flight in a wind field

    SciTech Connect

    Feldman, M.A.; Cliff, E.M.

    1994-12-31

    Optimal shaping of aerospace trajectories has provided the motivation for much modern study of optimization theory and algorithms. Current industrial practice favors approaches where the continuous-time optimal control problem is transcribed to a finite-dimensional nonlinear programming problem (NLP) by a discretization process. Two such formulations are implemented in the POST and the OTIS codes. In the present paper we use a discretization that is specially adapted to the flight problem of interest. Among the unique aspects of the present discretization are: a least-squares formulation for certain kinematic constraints; the use of an energy ideas to enforce Newton`s Laws; and, the inclusion of large magnitude horizontal winds. In the next section we shall provide a description of the flight problem and its NLP representation. Following this we provide some details of the constraint formulation. Finally, we present an overview of the NLP problem.

  1. Coincident vortices in Antarctic wind fields and sea ice motion

    NASA Astrophysics Data System (ADS)

    Wassermann, S.; Schmitt, C.; Kottmeier, C.; Simmonds, I.

    2006-08-01

    This study introduces a method to examine the coincidence of rotational ice drift and winds caused by the forcing of ice motion by Antarctic cyclones. Vortices are automatically detected using the algorithm of Murray and Simmonds (1991) from both ECMWF surface pressures and SSM/I sea ice motions. For compatibility with this algorithm sea ice motion vectors are transformed to a scalar stream function. During a seven-day test period positions of pressure minima and stream function maxima (SFM) of ice drift are within 300 km in 96% of the cases. Lowest pressure minima are related to highest stream function maxima. The results promise the method to provide a complementary tool of detecting and localizing low-pressure systems over sea ice, adding to numerical pressure analyses.

  2. Magnetic Cloud Field Intensities and Solar Wind Velocities

    NASA Technical Reports Server (NTRS)

    Gonzalez, Walter D.; Clau de Gonzalez, Alicia D.; Tsurutani, Bruce T.; Arballo, John K.

    1997-01-01

    For the sets of magnetic clouds studied in this work we have shown that there is a general relationship between their magnetic fields strength and velocities. With a clear tendency that the faster the speed of the cloud the higher the magnetic field.

  3. Hurricane Wind Field Measurements with Scanning Airborne Doppler Lidar During CAMEX-3

    NASA Technical Reports Server (NTRS)

    Rothermel, Jeffry; Cutten, D. R.; Howell, J. N.; Darby, L. S.; Hardesty, R. M.; Traff, D. M.; Menzies, R. T.

    2000-01-01

    During the 1998 Convection and Moisture Experiment (CAMEX-3), the first hurricane wind field measurements with Doppler lidar were achieved. Wind fields were mapped within the eye, along the eyewall, in the central dense overcast, and in the marine boundary layer encompassing the inflow region. Spatial coverage was determined primarily by cloud distribution and opacity. Within optically-thin cirrus slant range of 20- 25 km was achieved, whereas no propagation was obtained during penetration of dense cloud. Measurements were obtained with the Multi-center Airborne Coherent Atmospheric Wind Sensor (MACAWS) on the NASA DC-8 research aircraft. MACAWS was developed and operated cooperatively by the atmospheric lidar remote sensing groups of NOAA Environmental Technology Laboratory, NASA Marshall Space Flight Center, and Jet Propulsion Laboratory. A pseudo-dual Doppler technique ("co-planar scanning") is used to map the horizontal component of the wind at several vertical levels. Pulses from the laser are directed out the left side of the aircraft in the desired directions using computer-controlled rotating prisms. Upon exiting the aircraft, the beam is completely eyesafe. Aircraft attitude and speed are taken into account during real-time signal processing, resulting in determination of the ground-relative wind to an accuracy of about 1 m/s magnitude and about 10 deg direction. Beam pointing angle errors are about 0.1 deg, equivalent to about 17 m at 10 km. Horizontal resolution is about 1 km (along-track) for typical signal processor and scanner settings; vertical resolution varies with range. Results from CAMEX-3 suggest that scanning Doppler wind lidar can complement airborne Doppler radar by providing wind field measurements in regions that are devoid of hydrometeors. At present MACAWS observations are being assimilated into experimental forecast models and satellite Doppler wind lidar simulations to evaluate the relative impact.

  4. Interaction of solar wind with Mercury and its magnetic field. [as observed by Mariner 10 space probe

    NASA Technical Reports Server (NTRS)

    Ness, N. F.; Behannon, K. W.; Lepping, R. P.; Whang, Y. C.

    1976-01-01

    A brief review is presented of magnetic field and solar wind electron observations by Mariner 10 spacecraft. The intrinsic magnetic field of the planet Mercury and the implications of such a field for the planetary interior are also discussed.

  5. Estimated return periods for Hurricane Katrina

    NASA Astrophysics Data System (ADS)

    Elsner, J. B.; Jagger, T. H.; Tsonis, A. A.

    2006-04-01

    Hurricane Katrina is one of the most destructive natural disaster in U.S. history. The infrequency of severe coastal hurricanes implies that empirical probability estimates of the next big one will be unreliable. Here we use an extreme-value model together with interpolated best-track (HURDAT) records to show that a hurricane of Katrina's intensity or stronger can be expected to occur, on average, once every 21 years somewhere along the Gulf coast from Texas through Alabama and once every 14 years somewhere along the entire coast from Texas through Maine. The model predicts a 100-year return level of 83 ms-1 (186 mph) during globally warm years and 75 ms-1 (168 mph) during globally cool years. This difference is consistent with models predicting an increase in hurricane intensity with increasing greenhouse warming.

  6. Heat conduction in a turbulent magnetic field, with application to solar-wind electrons.

    NASA Technical Reports Server (NTRS)

    Hollweg, J. V.; Jokipii, J. R.

    1972-01-01

    Consideration of random, long-wavelength fluctuations in a turbulent magnetic field, showing that they can appreciably decrease the heat conductivity of a plasma along the magnetic field. In simple cases of interest, the reduction along the average field is approximately by the factor (cos delta theta) squared, where delta theta is the angle of the local magnetic field relative to the average field. Application to solar-wind electrons indicates that this reduction in heat conductivity due to observed fluctuations in the interplanetary magnetic field may be of the order of a factor of 2. This may help to explain recent measurements which indicate a rather low electron heat flux in the solar wind.

  7. The influence of the tropics on the prediction of ultralong waves. I - Tropical wind field

    NASA Technical Reports Server (NTRS)

    Baker, W. E.; Paegle, J.

    1983-01-01

    The effects of tropical wind data from the FGGE and tropical latent heating on numerical modeling of ultralong waves are considered in a two-part study. The model studied is the global fourth-order GLAS general circulation model, an energy-conserving format with horizontal differences calculated with fourth-order accuracy. Data assimilation experiments were performed with and without the wind data, with account taken of eastward and northward wind components, the geopotential height, and the relative humidity, all over pressure surfaces. The initial conditions were used to generate six pairs of forecasts, and the tropical wind error decreased after two days of prediction when the initial conditions contained the wind data. The deviations from the measured planetary wave data were attributed to differences in the initial rotational wind field, which varied on a three-day basis. The latent heat initial data had a five-day period and extended its influence beyond the tropical zone. The tropical heat sources sustained the tropical westerlies in the GLAS model, and removal of the tropical heat sources reversed the wind to easterlies.

  8. Katrina: macro-ethical issues for engineers.

    PubMed

    Newberry, Byron

    2010-09-01

    Hurricane Katrina was one of the worst disasters in United States history. Failures within New Orleans' engineered hurricane protection system (levees and floodwalls) contributed to the severity of the event and have drawn considerable public attention. In the time since Katrina, forensic investigations have uncovered a range of issues and problems related to the engineering work. In this article, my goal is to distill from these investigations, and the related literature that has accumulated, some overarching macro-ethical issues that are relevant for all engineers. I attempt to frame these issues, using illustrative examples taken from Katrina, in a way that might be of pedagogical use and benefit for engineering educators interested in engaging their students in discussions of engineering ethics, societal impact of engineered systems, engineering design, or related topics. Some of the issues discussed are problems of unanticipated failure modes, faulty assumptions, lack or misuse of information, the importance of resiliency, the effects of time, balancing competing interests, attending to the details of interfaces, the fickleness of risk perception, and how the past constrains the present.

  9. Field-Aligned Current Sheet Motion and Its Correlation with Solar Wind Conditions and Geomagnetic Activities

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Le, G.; Boardsen, S. A.; Slavin, J. A.; Strangeway, R. J.

    2008-05-01

    Field-aligned currents (FACs) are the currents flowing into and out of the ionosphere which connect to the magnetosphere. They provide an essential linkage between the solar wind - magnetosphere system and the ionosphere, and the understanding of these currents is important for global magnetosphere dynamics and space weather prediction. The three spacecraft ST-5 constellation provides an unprecedented opportunity to study in situ FAC dynamics in time scales (10 sec to 10 min) that can not be achieved previously with single spacecraft studies or large-spaced conjugate spacecraft studies. In this study, we use the magnetic field observations during the whole ST-5 mission and their corresponding solar wind conditions to study the dependence of FAC current sheet motion and intensity on solar wind conditions. FAC peak current densities show very good correlations with some solar wind parameters, including IMF Bz, dynamic pressure, Ey, and some IMF angles, but not with other parameters. Instant FAC speeds show generally much weaker dependence on solar wind conditions comparing to FAC peak current densities. This obvious uncorrelation between FAC peak current densities and speeds implies that FAC peak current densities are more consistently controlled by solar wind conditions and geomagnetic activities, while FAC speeds are more oscillatory, sometimes with higher speeds during quieter times and lower speeds during more turbulent times.

  10. Turbine-scale wind field measurements using dual-Doppler lidar

    SciTech Connect

    Newsom, Rob K.; Berg, Larry K.; Shaw, William J.; Fischer, Marc

    2015-02-01

    Spatially resolved measurements of micro-scale winds are retrieved using scanning dual-Doppler lidar, and validated against independent in situ wind measurements. Data for this study were obtained during a month-long field campaign conducted at a site in north-central Oklahoma in November of 2010. Observational platforms include one heavily instrumented 60-m meteorological tower and two scanning coherent Doppler lidars. The lidars were configured to perform coordinated dual-Doppler scans surrounding the 60-m tower, and the resulting radial velocity observations were processed to retrieve the 3-component velocity vector field on surfaces defined by the intersecting scan planes. Raw radial velocity measurements from the lidars were calibrated by direct comparison to a sonic anemometer located at the 60 m level on the tower. Wind retrievals were performed using both calibrated and uncalibrated measurements, and validated against the 60-m sonic anemometer observations. Retrievals using uncalibrated radial velocity data show a significant slow bias in the wind speed of about 14%; whereas the retrievals using the calibrated data show a much smaller slow bias of 1.2%. Retrievals using either the calibrated or uncalibrated data exhibit negligible bias in the wind direction (<0.2o), and excellent correlation in the wind speeds (>0.96).

  11. Wind field near complex terrain using numerical weather prediction model

    NASA Astrophysics Data System (ADS)

    Chim, Kin-Sang

    The PennState/NCAR MM5 model was modified to simulate an idealized flow pass through a 3D obstacle in the Micro- Alpha Scale domain. The obstacle used were the idealized Gaussian obstacle and the real topography of Lantau Island of Hong Kong. The Froude number under study is ranged from 0.22 to 1.5. Regime diagrams for both the idealized Gaussian obstacle and Lantau island were constructed. This work is divided into five parts. The first part is the problem definition and the literature review of the related publications. The second part briefly discuss as the PennState/NCAR MM5 model and a case study of long- range transport is included. The third part is devoted to the modification and the verification of the PennState/NCAR MM5 model on the Micro-Alpha Scale domain. The implementation of the Orlanski (1976) open boundary condition is included with the method of single sounding initialization of the model. Moreover, an upper dissipative layer, Klemp and Lilly (1978), is implemented on the model. The simulated result is verified by the Automatic Weather Station (AWS) data and the Wind Profiler data. Four different types of Planetary Boundary Layer (PBL) parameterization schemes have been investigated in order to find out the most suitable one for Micro-Alpha Scale domain in terms of both accuracy and efficiency. Bulk Aerodynamic type of PBL parameterization scheme is found to be the most suitable PBL parameterization scheme. Investigation of the free- slip lower boundary condition is performed and the simulated result is compared with that with friction. The fourth part is the use of the modified PennState/NCAR MM5 model for an idealized flow simulation. The idealized uniform flow used is nonhydrostatic and has constant Froude number. Sensitivity test is performed by varying the Froude number and the regime diagram is constructed. Moreover, nondimensional drag is found to be useful for regime identification. The model result is also compared with the analytic

  12. An integrated approach for wind fields assessment in coastal areas, based on bioindicators, CFD modeling, and observations

    NASA Astrophysics Data System (ADS)

    Meneses, Bruno M.; Lopes, António

    2015-12-01

    Wind-deformed trees can be good bioindicators of the mean wind speed and prevailing wind directions. The current research used bioindicators, computational fluid dynamics (CFD), and linear models to assess the wind fields in the windy coastal area of Cascais/Portugal. The main objectives of this research are to assess mean speed and directions of winds by using bioindicators and modeling techniques and to correlate both results in order to assess the best methods. The results obtained with the bioindicators showed that carpeting, the most severe deformation, was observed near the shoreline showing that the highest wind speeds are felt in this sector. Inland, where the winds have lower mean speeds, flagging forms are more frequent. When correlated with the bioindicators, the linear model gave better results than CFD models. We can conclude that in areas with good wind potential, the use of bioindicators can be a good alternative in the absence of wind data.

  13. The Magnetic Field of Mars and its Interaction with the Solar Wind

    NASA Technical Reports Server (NTRS)

    Le, Guan; Slavin, James A.

    2009-01-01

    The outermost layers of the Martian atmosphere are thought to be scientifically unique due to the large influences exerted by the highly dynamic lower atmosphere and the direct input of the solar wind from above. The nature of the solar wind interaction with the upper atmosphere is of particular interest because Mars lacks a global magnetic field, but is well shielded over some regions by strong crustal magnetic fields. Under such circumstances, the direct impact of solar wind plasma may have resulted in enhanced loss of volatiles over the ages including the components of water. The history of upper atmosphere and solar wind interaction measurements at Mars will be reviewed, recent results from the Mars Global Surveyor and Mars Express summarized, and prospects for new scientific advances enabled by the measurements that will be made by planned orbiter and penetrator missions. Special attention will be given to planetary magnetic field measurements, the measurement of ionospheric currents driven by the solar wind, and the role of space weather modeling and forecasting in the future of Mars exploration.

  14. Interplanetary field enhancements in the solar wind Statistical properties at 0.72 AU

    NASA Technical Reports Server (NTRS)

    Russell, C. T.; Arghavani, M. R.; Luhmann, J. G.

    1984-01-01

    A new class of disturbance in the interplanetary magnetic field has been discovered. This disturbance consists of an enhancement in the magnetic field strength lasting tens of minutes to hours. The strength of the enhancement is variable ranging up to over double the background field strength. The peak field pressure can be as high as 10 percent of the solar wind dynamic pressure. These events occur randomly with respect to the position of the spacecraft relative to Venus but not randomly with respect to Venus solar ecliptic longitude. There is a significant tendency for these events to cluster near certain ecliptic longitudes. The field distortion is often greater in the direction perpendicular to the solar wind flow rather than along it. These characteristics suggest that the source of the disturbances are weakly outgassing objects, possibly dispersed along their orbits such as in meteor streams.

  15. Configuration and Evaluation of a Dual-Doppler 3-D Wind Field System

    NASA Technical Reports Server (NTRS)

    Crawford, Winifred C.

    2014-01-01

    Current LSP, GSDO, and SLS space vehicle operations are halted when wind speeds from specific directions exceed defined thresholds and when lightning is a threat. Strong winds and lightning are difficult parameters for the 45th Weather Squadron (45 WS) to forecast, yet are important in the protection of customer vehicle operations and the personnel that conduct them. A display of the low-level horizontal wind field to reveal areas of high winds or convergence would be a valuable tool for forecasters in assessing the timing of high winds, or convection initiation and subsequent lightning occurrence. This is especially important for areas where no weather observation platforms exist. Developing a dual-Doppler radar capability would provide such a display to assist forecasters in predicting high winds and convection initiation. The wind fields can also be used to initialize a local mesoscale numerical weather prediction model to help improve the model forecast winds, convection initiation, and other phenomena. The 45 WS and NWS MLB tasked the Applied Meteorology Unit (AMU) to develop a dual- Doppler wind field display using data from the 45th Space Wing radar, known as the Weather Surveillance Radar (WSR), NWS MLB Weather Surveillance Radar 1988 Doppler (KMLB), and the Orlando International Airport Terminal Doppler Weather Radar (KMCO). They also stipulated that the software used should be freely available. The AMU evaluated two software packages and, with concurrence from NWS MLB and the 45 WS, chose the Warning Decision Support System-Integrated Information (WDSS-II). The AMU collected data from two significant weather cases: a tornadic event on 14 April 2013 and a severe wind and hail event on 12 February 2014. For the 14 April case, the data were from WSR and KMLB. For the 12 February case, the data were from KMCO and KMLB. The AMU installed WDSS-II on a Linux PC, then processed and quality controlled the radar data for display and analysis using WDSS-II tools

  16. Toward Transformative Learning: An Inquiry into the Work and Subsequent Learning Experiences of Individuals Who Assisted Hurricane Katrina Evacuees

    ERIC Educational Resources Information Center

    Ficks, David B., II.

    2010-01-01

    The purpose of this multi-case study was to examine in depth the personal and learning experiences of helping professionals and volunteer helpers when challenged to assist adult Hurricane Katrina evacuees and victims in the aftermath of the disaster. The study contributes theoretically, practically and substantively to the adult education field.…

  17. Breakup of New Orleans Households after Hurricane Katrina

    ERIC Educational Resources Information Center

    Rendall, Michael S.

    2011-01-01

    Theory and evidence on disaster-induced population displacement have focused on individual and population-subgroup characteristics. Less is known about impacts on households. I estimate excess incidence of household breakup resulting from Hurricane Katrina by comparing a probability sample of pre-Katrina New Orleans resident adult household heads…

  18. Stakeholder Organizations: Hurricane Katrina and the New Orleans Public Schools

    ERIC Educational Resources Information Center

    Beabout, Brian

    2007-01-01

    In the aftermath of Hurricane Katrina, the district temporarily lost 100% of its students and did not reopen a single school for more than two months. As it became apparent that the district was not prepared to bring the schools back from such a devastating blow, educators began to see a silver lining in Katrina's dark clouds. State School Board…

  19. Effects of Hurricane Katrina on the forest structure of taxodium distichum swamps of the Gulf Coast, USA

    USGS Publications Warehouse

    Middleton, B.A.

    2009-01-01

    Hurricane Katrina pushed mixed Taxodium distichum forests toward a dominance of Taxodium distichum (baldcypress) and Nyssa aquatica (water tupelo) because these species had lower levels of susceptibility to wind damage than other woody species. This study documents the volume of dead versus live material of woody trees and shrubs of T. distichum swamps following Hurricane Katrina along the Gulf Coast of Mississippi and Louisiana. Pearl River Wildlife Management Area near Canton, Mississippi had the highest winds of the study areas, and these forests were located in the northeast quadrant of Hurricane Katrina (sustained wind 151 kph (94 mph)). Jean Lafitte National Historical Park and Preserve south of New Orleans had medium to high winds (sustained winds 111 kph (69 mph) at the New Orleans lakefront). Cat Island National Wildlife Refuge had a lower level of winds and was positioned on the western edge of the storm. The forests at Pearl River and to a lesser extent at Jean Lafitte had the highest amount of structural damage in the study. For Cat Island, Jean Lafitte, and Pearl River, the total volume of dead material (debris) was 50, 80, and 370 m3 ha-1, respectively. The ratio of dead to live volume was 0.010, 0.082, and 0.039, respectively. For both of the dominant species, T. distichum and N. aquatica, the percentage of dead to live volume was less than 1. Subdominant species including Acer rubrum, Liquidambar styraciflua, Quercus lyrata, and Quercus nigra were more damaged by the storm at both Pearl River and Jean Lafitte. Only branches were damaged by Hurricane Katrina at Cat Island. Shrubs such as Morella cerifera, Euonymous sp., and Vaccinium sp. were often killed by the storm, while other species such as Cephalanthus occidentalis, Forestiera acuminata, and Cornus florida were not killed. Despite the fact that Hurricane Katrina was a Category 3 storm and struck Pearl River and Jean Lafitte fairly directly, dominant species of the T. distichum swamps were

  20. The intrinsic magnetic field and solar-wind interaction of Mars

    NASA Technical Reports Server (NTRS)

    Luhmann, J. G.; Russell, C. T.; Brace, L. H.; Vaisberg, O. L.

    1992-01-01

    The Venus-like interaction between the solar wind and the atmosphere of Mars is examined. The bow shock and magnetosheath of Mars indicate the presence of an obstacle to the solar wind that is somewhat larger than the size of the planet and its observed ionosphere, and also relatively larger than the Venus obstacle under comparable conditions. The intrinsic magnetic field of Mars must be no greater than 1.5 x 10 exp 12 T/cu m, or about 0.0001 times as strong as that of the earth to produce an obstacle of such small size. At least for solar minimum conditions, like those prevailing at the time of the Viking Landers, the ionospheric plasma (thermal) pressure is insufficient to balance the incident solar-wind pressure by itself. The ion and electron temperatures in the Martian ionosphere indicate the presence of local horizontal magnetic fields and heat sources in excess of solar radiation alone.

  1. Wide field-of-view soft X-ray imaging for solar wind-magnetosphere interactions

    NASA Astrophysics Data System (ADS)

    Walsh, B. M.; Collier, M. R.; Kuntz, K. D.; Porter, F. S.; Sibeck, D. G.; Snowden, S. L.; Carter, J. A.; Collado-Vega, Y.; Connor, H. K.; Cravens, T. E.; Read, A. M.; Sembay, S.; Thomas, N. E.

    2016-04-01

    Soft X-ray imagers can be used to study the mesoscale and macroscale density structures that occur whenever and wherever the solar wind encounters neutral atoms at comets, the Moon, and both magnetized and unmagnetized planets. Charge exchange between high charge state solar wind ions and exospheric neutrals results in the isotropic emission of soft X-ray photons with energies from 0.1 to 2.0 keV. At Earth, this process occurs primarily within the magnetosheath and cusps. Through providing a global view, wide field-of-view imaging can determine the significance of the various proposed solar wind-magnetosphere interaction mechanisms by evaluating their global extent and occurrence patterns. A summary of wide field-of-view (several to tens of degrees) soft X-ray imaging is provided including slumped micropore microchannel reflectors, simulated images, and recent flight results.

  2. Mapping ERS-1 wind fields over north west Atlantic using a variational objective analysis

    NASA Technical Reports Server (NTRS)

    Siefridt, L.; Legler, D. M.; Barnier, B.; Obrien, J. J.

    1994-01-01

    A variational method is implemented to produce five day mean gridded ERS-1 analyzed wind fields in the north west Atlantic with the aim of providing for wind forcing of basin scale ocean models. The method consists of minimizing a cost functional, designed to measure misfits to prescribed weighted constraints which express a smoothed behavior and the proximity to input data vectors and curl. The weights are empirically determined by comparison with independent ship and buoy data over four five day periods. Root mean square differences between analyzed winds and independent data are thus further decreased: they range from 0.8 up to 1.8 m/s. Some problems present in the initial data remain; they are principally due to incomplete data coverage (instrumental problems), and possibly unresolved ambiguities. The resulting curl fields are smoothed and show coherent patterns. A comparison with the European Center for Medium range Weather Forecasting (ECMWF) analysis is encouraging.

  3. Analytical comparison of hypersonic flight and wind tunnel viscous/inviscid flow fields

    NASA Technical Reports Server (NTRS)

    Fivel, H. J.; Masek, R. V.; Mockapetris, L. J.

    1975-01-01

    Flow fields were computed about blunted, 0.524 and 0.698 radians, cone configurations to assess the effects of nonequilibrium chemistry on the flow field geometry, boundary layer edge conditions, boundary layer profiles, and heat transfer and skin friction. Analyses were conducted at typical space shuttle entry conditions for both laminar and turbulent boundary layer flow. In these calculations, a wall temperature of 1365 K (2000 F) was assumed. The viscous computer program used in this investigation was a modification of the Blottner non-similar viscous code which incorporated a turbulent eddy viscosity model after Cebeci. The results were compared with equivalent calculations for similar (scaled) configurations at typical wind tunnel conditions. Wind tunnel test gases included air, nitrogen, CF4 and helium. The viscous computer program used for wind tunnel conditions was the Cebeci turbulent non-similar computer code.

  4. [Distribution of Regional Pollution and the Characteristics of Vertical Wind Field in the Pearl River Delta].

    PubMed

    Liu, Jian; Wu, Dui; Fan, Shao-jia

    2015-11-01

    Based on the data of hourly PM2.5 concentration of 56 environmental monitoring stations and 9 cities over the Pearl River Delta (PRD) region, the distributions of PM2.5 pollution in PRD region were analyzed by systematic cluster analysis and correlational analysis. It was found that the regional pollution could be divided into 3 types. The first type was the pollution occurred in Dongguan, Guangzhou, Foshan and Jiangmen (I type), and the second type was the pollution occurred in Zhongshan, Zhuhai, Shenzhen and Huizhou (II type), while the last type was the pollution only occurred in Zhaoqing (III type). During the study period, they occurred 47, 7 and 128 days, respectively. During events of pollution type I, except Zhuhai, Shenzhen and Huizhou, the PM2.5 concentrations of other cities were generally high, while the PM2.5 concentration in whole PRD region was over 50.0 μg x m(-3) during events of pollution type II. The regions with higher PM2.5 concentration was mainly concentrated in Zhaoqing, Guangzhou and Foshan during events of pollution type III. The wind data from 4 wind profile radars located in PRD region was used to study the characteristics of vertical wind field of these 3 pollution types. It was found that the wind profiles of type I and III were similar that low layer and high layer were controlled by the southeast wind and the southwest wind, respectively. For type II, the low layer and high layer were influenced by northerly wind and westerly wind, respectively. Compared with other types, the wind speed and ventilation index of type II. were much higher, and the variation of wind direction at lower-middle-layer was much smaller. When PRD region was influenced by northerly winds, the PM2.5 concentration in the entire PRD region was higher. When PRD region was controlled by southeast wind, the PM2.5 concentrations of I and II areas were relatively lower, while the pollution in III area was relatively heavier.

  5. Measuring electromagnetic fields (EMF) around wind turbines in Canada: is there a human health concern?

    PubMed Central

    2014-01-01

    Background The past five years has seen considerable expansion of wind power generation in Ontario, Canada. Most recently worries about exposure to electromagnetic fields (EMF) from wind turbines, and associated electrical transmission, has been raised at public meetings and legal proceedings. These fears have not been based on any actual measurements of EMF exposure surrounding existing projects but appear to follow from worries from internet sources and misunderstanding of the science. Methods The study was carried out at the Kingsbridge 1 Wind Farm located near Goderich, Ontario, Canada. Magnetic field measurements were collected in the proximity of 15 Vestas 1.8 MW wind turbines, two substations, various buried and overhead collector and transmission lines, and nearby homes. Data were collected during three operational scenarios to characterize potential EMF exposure: ‘high wind’ (generating power), ‘low wind’ (drawing power from the grid, but not generating power) and ‘shut off’ (neither drawing, nor generating power). Results Background levels of EMF (0.2 to 0.3 mG) were established by measuring magnetic fields around the wind turbines under the ‘shut off’ scenario. Magnetic field levels detected at the base of the turbines under both the ‘high wind’ and ‘low wind’ conditions were low (mean = 0.9 mG; n = 11) and rapidly diminished with distance, becoming indistinguishable from background within 2 m of the base. Magnetic fields measured 1 m above buried collector lines were also within background (≤ 0.3 mG). Beneath overhead 27.5 kV and 500 kV transmission lines, magnetic field levels of up to 16.5 and 46 mG, respectively, were recorded. These levels also diminished rapidly with distance. None of these sources appeared to influence magnetic field levels at nearby homes located as close as just over 500 m from turbines, where measurements immediately outside of the homes were ≤ 0.4 mG. Conclusions The results suggest that there is

  6. Analysis of aerodynamic field and noise of a small wind turbine

    NASA Astrophysics Data System (ADS)

    Niculescu, Mihai Leonida; Cojocaru, Marius Gabriel; Pricop, Mihai Victor

    2012-11-01

    The wind energy is deemed as one of the most durable energetic variants of the future because the wind resources are immense. Furthermore, one predicts that the small wind turbine will play a vital role in the urban environment. Unfortunately, nowadays, the noise emissions from wind turbines represent one of the main obstacles to widespread the use in populated zones. Moreover, the energetic efficiency of these wind turbines has to be high even at low and medium wind velocities because, usually the cities are not windy places. The numerical results clearly show that the wakes after the trailing edge are the main noise sources. In order to decrease the power of these noise sources, we should try to decrease the intensity of wakes after the trailing edge, i.e. the aerodynamic fields from pressure and suction sides would have to be almost the same near trailing edge. Furthermore, one observes a strong link between transport (circumferential) velocity and acoustic power level, i.e. if the transport velocity increases, the acoustic power level also augments.

  7. Structures in the polar solar wind: Plasma and field observations from Ulysses

    SciTech Connect

    McComas, D.J.; Barraclough, B.L.; Gosling, J.T.; Hammond, C.M.; Phillips, J.L.; Neugebauer, M.; Balogh, A.; Forsyth, R.J.

    1996-07-01

    The Ulysses measurements of the solar wind plasma and magnetic fields for the 36-69 deg.south latitude are analyzed. The plasma compressional structures and pressure balance structures are identified in addition to Alfven waves and coronal mass ejection. {copyright} {bold 1997 American Institute of Physics.}

  8. Effects of heterogeneous wind fields and vegetation composition on modeled estimates of pollen source area

    NASA Astrophysics Data System (ADS)

    Burke, K. D.; Goring, S. J.; Williams, J. W.; Holloway, T.

    2015-12-01

    Fossil pollen records from lakes, bogs, and small hollows offer the main source of information about vegetation responses to climate change and land use over timescales of decades to millennia. Millions of pollen grains are released from individual trees each year, and are transported by wind before settling out of the atmosphere. Reconstructing past vegetation from sedimentary pollen records, however, requires careful modeling of pollen production, transport, and deposition. The atmosphere is turbulent, and regional wind patterns shift from day to day. In accordance with this, it is necessary for pollen transport models to adequately account for variable, non-uniform wind patterns and vegetation heterogeneity. Using a simulation approach, with both simulated vegetation patterns and vegetation gradients, as well as simulated wind fields, we show the inconsistency in pollen loading proportions and local vegetation proportions when non-uniform wind patterns are incorporated. Vegetation upwind from the lake is over-represented due to the increased prevalence of winds transporting pollen from that area. The inclusion of North American Regional Reanalysis (NARR) wind records affirms this finding. Of the lake sites explored in this study, none had uniform wind patterns. The use of a settlement-era gridded vegetation dataset, compiled by the PalEON project and based on Public Land Survey System (PLSS) records allows us to model pollen source area with realistic vegetation heterogeneity. Due to differences in productivity, pollen fall speeds, and neighboring vegetation, there exist patterns of vegetation that may be poorly characterized due to over/under representation of different taxa. Better understanding these differences in representation allows for more accurate reconstruction of historical vegetation, and pollen-vegetation relationships.

  9. Thigmomorphogenesis: field and laboratory studies of Abies fraseri in response to wind or mechanical perturbation.

    PubMed

    Telewski, F W; Jaffe, M J

    1986-01-01

    Field- and greenhouse-grown Abies fraseri (Pursh) Poir. (Fraser fir) were analyzed for wind- or mechanically-induced flexure changes. These changes included inhibition of stem and needle elongation, reinforcement of branch bases around the stem, and increased radial growth in the direction of the mechanical perturbation (MP). Mature trees exposed to high wind conditions were severely flag-formed. These modified tree crowns had a lower drag than crowns of non-flag formed trees in wind-tunnel tests. In both field-grown and greenhouse-grown A. fraseri, MP induced a decrease in flexibility and increased elasticity of the stems. The increased radial growth of the stems overrode the increase in elasticity, resulting in the overall decrease in flexibility. The increase in radial growth caused by wind or mechanical flexure was due to greater cell divisions of the vascular cambium, resulting in increased numbers of tracheids. The decrease in stem elongation in these trees was due, at least in part, to a decrease in tracheid length. The potential biological and mechanical significance of these induced growth changes in trees are addressed. The data support the thigmomorphogenetic theory, which states that plants respond to wind and other mechanical perturbations in a way that is favorable to the plant for continued survival in windy environments.

  10. Thigmomorphogenesis: field and laboratory studies of Abies fraseri in response to wind or mechanical perturbation

    NASA Technical Reports Server (NTRS)

    Telewski, F. W.; Jaffe, M. J.

    1986-01-01

    Field- and greenhouse-grown Abies fraseri (Pursh) Poir. (Fraser fir) were analyzed for wind- or mechanically-induced flexure changes. These changes included inhibition of stem and needle elongation, reinforcement of branch bases around the stem, and increased radial growth in the direction of the mechanical perturbation (MP). Mature trees exposed to high wind conditions were severely flag-formed. These modified tree crowns had a lower drag than crowns of non-flag formed trees in wind-tunnel tests. In both field-grown and greenhouse-grown A. fraseri, MP induced a decrease in flexibility and increased elasticity of the stems. The increased radial growth of the stems overrode the increase in elasticity, resulting in the overall decrease in flexibility. The increase in radial growth caused by wind or mechanical flexure was due to greater cell divisions of the vascular cambium, resulting in increased numbers of tracheids. The decrease in stem elongation in these trees was due, at least in part, to a decrease in tracheid length. The potential biological and mechanical significance of these induced growth changes in trees are addressed. The data support the thigmomorphogenetic theory, which states that plants respond to wind and other mechanical perturbations in a way that is favorable to the plant for continued survival in windy environments.

  11. Plasma and field observation of the structures in the polar solar wind

    NASA Technical Reports Server (NTRS)

    McComas, D. J.; Barraclough, B. L.; Gosling, J. T.; Hammond, C. M.; Phillips, J. L.; Neugebauer, M.; Balogh, A.; Forsyth, R. J.

    1995-01-01

    Since passing essentially continuously into regions of solar wind from the southern polar coronal hole at approximately 36 deg S, Ulysses has observed frequent structures lasting from several hours to several days. In addition to Alfven waves and coronal mass ejections, which have been discussed by previous authors, two other sorts of structures are routinely evident. This paper provides the first report of these structures in the high latitude solar wind: (1) small scale compressional structures, and (2) pressure balance structures. The compressional structures are driven by faster solar wind overtaking the slower solar wind ahead of it and exhibit the plasma and field properties expected for compressions. However, unlike large scale stream interaction regions observed in and near the ecliptic plane, these structures are much smaller scale and are transient, not recurring from one rotation to the next. The pressure balance structures are indicated by roughly equal increases in the plasma pressure and decreases in the magnetic field pressure. These structures, which are several degrees across, are more dense and have higher plasma pressures and betas than the surrounding solar wind. These pressure balance structures seem to be likely manifestations of 'polar plumes.'

  12. A Five-Parameter Wind Field Estimation Method Based on Spherical Upwind Lidar Measurements

    NASA Astrophysics Data System (ADS)

    Kapp, S.; Kühn, M.

    2014-12-01

    Turbine mounted scanning lidar systems of focussed continuous-wave type are taken into consideration to sense approaching wind fields. The quality of wind information depends on the lidar technology itself but also substantially on the scanning technique and reconstruction algorithm. In this paper a five-parameter wind field model comprising mean wind speed, vertical and horizontal linear shear and homogeneous direction angles is introduced. A corresponding parameter estimation method is developed based on the assumption of upwind lidar measurements scanned over spherical segments. As a main advantage of this method all relevant parameters, in terms of wind turbine control, can be provided. Moreover, the ability to distinguish between shear and skew potentially increases the quality of the resulting feedforward pitch angles when compared to three-parameter methods. It is shown that minimal three measurements, each in turn from two independent directions are necessary for the application of the algorithm, whereas simpler measurements, each taken from only one direction, are not sufficient.

  13. Stable paths of the Kuroshio south of Japan determined by the wind stress field

    NASA Astrophysics Data System (ADS)

    Kurogi, Masao; Akitomo, Kazunori

    2003-10-01

    To investigate the role of the wind stress field in determining stable paths of the Kuroshio south of Japan, we have executed numerical experiments with a two-layer, wind-driven ocean model, changing zonal and meridional wind stress distributions. Four types of path (two straight and two meandering paths) have been found, and their appearance has been classified into three categories. In category I, straight and meandering paths coexist (multiple equilibrium); only a meandering (straight) path appears in category II (III). A meandering path tends to appear when the Sverdrup transport along the southern coast of Japan decreases downstream strongly and the wind stress curl is anomalously negative in the western region near Japan, whereas a straight path is apt to occur with the positive anomaly. Detailed examination of the results has revealed the following mechanism determining stable paths of the Kuroshio. The wind stress field first determines the pressure difference Δp* between the two ends of the southern coast of Japan. When Δp* is smaller than a certain threshold, only a meandering path can exist since the along-coast pressure decrease in a straight path state is much larger than Δp* (category II). Conversely, when Δp* is larger than another threshold, only a straight path is consistent with the larger Δp* (category III). Both paths can appear when Δp* is between the two thresholds (category I). The climatological wind stress field in the North Pacific subtropical region has been suggested to be in category I.

  14. Field and numerical study of wind and surface waves at short fetches

    NASA Astrophysics Data System (ADS)

    Baydakov, Georgy; Kuznetsova, Alexandra; Sergeev, Daniil; Papko, Vladislav; Kandaurov, Alexander; Vdovin, Maxim; Troitskaya, Yuliya

    2016-04-01

    Measurements were carried out in 2012-2015 from May to October in the waters of Gorky Reservoir belonging to the Volga Cascade. The methods of the experiment focus on the study of airflow in the close proximity to the water surface. The sensors were positioned at the oceanographic Froude buoy including five two-component ultrasonic sensors WindSonic by Gill Instruments at different levels (0.1, 0.85, 1.3, 2.27, 5.26 meters above the mean water surface level), one water and three air temperature sensors, and three-channel wire wave gauge. One of wind sensors (0.1 m) was located on the float tracking the waveform for measuring the wind speed in the close proximity to the water surface. Basic parameters of the atmospheric boundary layer (the friction velocity u∗, the wind speed U10 and the drag coefficient CD) were calculated from the measured profiles of wind speed. Parameters were obtained in the range of wind speeds of 1-12 m/s. For wind speeds stronger than 4 m/s CD values were lower than those obtained before (see eg. [1,2]) and those predicted by the bulk parameterization. However, for weak winds (less than 3 m/s) CD values considerably higher than expected ones. The new parameterization of surface drag coefficient was proposed on the basis of the obtained data. The suggested parameterization of drag coefficient CD(U10) was implemented within wind input source terms in WAVEWATCH III [3]. The results of the numerical experiments were compared with the results obtained in the field experiments on the Gorky Reservoir. The use of the new drag coefficient improves the agreement in significant wave heights HS [4]. At the same time, the predicted mean wave periods are overestimated using both built-in source terms and adjusted source terms. We associate it with the necessity of the adjusting of the DIA nonlinearity model in WAVEWATCH III to the conditions of the middle-sized reservoir. Test experiments on the adjusting were carried out. The work was supported by the

  15. Neutral wind acceleration in the polar lower E-region during an intense electric-field

    NASA Astrophysics Data System (ADS)

    Tsuda, Takuo T.; Buchert, Stephan C.; Nozawa, Satonori; Oyama, Shin-ichiro; Ogawa, Yasunobu; Fujii, Ryoichi

    2016-04-01

    The Joule heating and ion drag effects are considered as important factors in the neutral wind dynamics in the polar E-region. However, quantitative evaluations for these effects are insufficient for correct understanding, particularly, in the lower E-region (100-110 km heights) where the anomalous heating effect, related with the electron Pedersen currents, can occur during the intense electric field. In the present study, using EISCAT Svalbard radar data, we have investigated, for the first time, the normal and anomalous heating effects to the neutral wind acceleration in the lower E-region.

  16. Contributions to the Fourth Solar Wind Conference. [interplanetary magnetic fields and medium

    NASA Technical Reports Server (NTRS)

    Acuna, M. H.; Behannon, K. W.; Burlaga, L. F.; Lepping, R.; Ness, N.; Ogilvie, K.; Pizzo, J.

    1979-01-01

    Recent results in interplanetary physics are examined. These include observations of shock waves and post-shock magnetic fields made by Voyager 1, 2; observations of the electron temperature as a function of distance between 1.36 AU and 2.25 AU; and observations of the structure of sector boundaries observed by Helios 1. A theory of electron energy transport in the collisionless solar wind is presented, and compared with observations. Alfven waves and Alvenic fluctuations in the solar wind are also discussed.

  17. Connecting the surface of the Sun to the Heliosphere : wind speed and magnetic field geometry

    NASA Astrophysics Data System (ADS)

    Pinto, Rui

    2016-07-01

    The large-scale solar wind speed distribution varies in time in response to the cyclic variations of the strength and geometry of the magnetic field of the corona. Based on this idea, semi-empirical predictive laws for the solar wind speed (such as in the widely-used WSA law) use simple parameters describing the geometry of the coronal magnetic field. In practice, such scaling laws require ad-hoc corrections and empirical fits to in-situ spacecraft data, and a predictive law based solely on physical principles is still missing. I will discuss improvements to this kind of laws based on the analysis of very large samples of wind acceleration profiles in open flux-tubes (both from MHD simulations and potential-field extrapolations), and possible strategies for corona and heliosphere model coupling. I will, furthermore present an ongoing modelling effort to determine the magnetic connectivity, paths and propagation delays of any type of disturbance (slow/fast solar wind, waves, energetic particles, ballistic propagation) between the solar surface and any point in the interplanetary space at any time. This is a key point for the exploitation of data from Solar Orbiter and Solar Probe Plus, and more generally for establishing connections between remote and in-situ spacecraft data. This is work is supported by the FP7 project #606692 (HELCATS).

  18. Seasonal wind fields as determined by the TIMED Doppler Interferometer (TIDI)

    NASA Astrophysics Data System (ADS)

    Skinner, W.; Niciejewski, R.; Killeen, T.; Solomon, S.; Gablehouse, D.; Wu, Q.; Ortland, D.; Gell, D.; Marshall, A.; Wolfe, E.; Cooper, M.; Kafkalidis, J.

    2003-12-01

    The TIMED Doppler Interferometer (TIDI) has been measuring the wind field in the mesosphere and lower thermosphere since early 2002. The instrument is a Fabry-Perot interferometer that simultaneously samples the limb of the Earth with four separate telescopes providing two forward views and two rearward views, one of each on either side of the orbital path. At equator crossings, these two side views are separated by about 30 degrees of longitude at the tangent point altitude, or 2 hours of local time. On any orbit TIDI obtains two horizontal vector winds at the dayside equator crossing and two on the nightside equator crossing for all low latitudes. The precession rate of TIMED requires a two month average of data to sample all local solar times This paper will describe the wind field that has been determined by the TIDI since operations commenced. The mean wind and tidal amplitudes are examined and seasonal variability examined. Results are also compared to fields measured earlier by HRDI and WINDII on the UARS spacecraft.

  19. Earth Observations to Assess Impact of Hurricane Katrina on John C. Stennis Space Center

    NASA Technical Reports Server (NTRS)

    Graham, William D.; Ross, Kenton W.

    2007-01-01

    The peril from hurricanes to Space Operations Centers is real and is forecast to continue; Katrina, Rita, and Wilma of 2005 and Charley, Frances, Ivan, and Jeanne of 2004 are sufficient motivation for NASA to develop a multi-Center plan for preparedness and response. As was demonstrated at SSC (Stennis Space Center) in response to Hurricane Katrina, NASA Centers are efficiently activated as local command centers, playing host to Federal and State agencies and first responders to coordinate and provide evacuation, relocation, response, and recovery activities. Remote sensing decision support provides critical insight for managing NASA infrastructure and for assisting Center decision makers. Managers require geospatial information to manage the federal city. Immediately following Katrina, SSC s power and network connections were disabled, hardware was inoperative, technical staff was displaced and/or out of contact, and graphical decision support tools were non-existent or less than fully effective. Despite this circumstance, SSC EOC (Emergency Operations Center) implemented response operations to assess damage and to activate recovery plans. To assist Center Managers, the NASA ASP (Applied Sciences Program) made its archive of high-resolution data over the site available. In the weeks and months after the immediate crisis, NASA supplemented this data with high-resolution, post-Katrina imagery over SSC and much of the affected coastal areas. Much of the high-resolution imagery was made available through the Department of Defense Clear View contract and was distributed through U.S. Geological Survey Center for Earth Resources Observation and Science "Hurricane Katrina Disaster Response" Web site. By integrating multiple image data types with other information sources, ASP applied an all-source solutions approach to develop decision support tools that enabled managers to respond to critical issues, such as expedient access to infrastructure and deployment of resources

  20. Ulysses Observations of Tripolar Guide-Magnetic Field Perturbations Across Solar Wind Reconnection Exhausts

    NASA Astrophysics Data System (ADS)

    Eriksson, S.; Peng, B.; Markidis, S.; Gosling, J. T.; McComas, D. J.; Lapenta, G.; Newman, D. L.

    2014-12-01

    We report observations from 15 solar wind reconnection exhausts encountered along the Ulysses orbit beyond 4 AU in 1996-1999 and 2002-2005. The events, which lasted between 17 and 45 min, were found at heliospheric latitudes between -36o and 21o with one event detected as high as 58o. All events shared a common characteristic of a tripolar guide-magnetic field perturbation being detected across the observed exhausts. The signature consists of an enhanced guide field magnitude within the exhaust center and two regions of significantly depressed guide-fields adjacent to the center region. The events displayed magnetic field shear angles as low as 37o with a mean of 89o. This corresponds to a strong external guide field relative to the anti-parallel reconnecting component of the magnetic field with a mean ratio of 1.3 and a maximum ratio of 3.1. A 2-D kinetic reconnection simulation for realistic solar wind conditions reveals that tripolar guide fields form at current sheets in the presence of multiple X-lines as two magnetic islands interact with one another for such strong guide fields. The Ulysses observations are also compared with the results of a 3-D kinetic simulation of multiple flux ropes in a strong guide field.

  1. Wetland sedimentation from hurricanes Katrina and Rita.

    PubMed

    Turner, R Eugene; Baustian, Joseph J; Swenson, Erick M; Spicer, Jennifer S

    2006-10-20

    More than 131 x 10(6) metric tons (MT) of inorganic sediments accumulated in coastal wetlands when Hurricanes Katrina and Rita crossed the Louisiana coast in 2005, plus another 281 x 10(6) MT when accumulation was prorated for open water area. The annualized combined amount of inorganic sediments per hurricane equals (i) 12% of the Mississippi River's suspended load, (ii) 5.5 times the inorganic load delivered by overbank flooding before flood protection levees were constructed, and (iii) 227 times the amount introduced by a river diversion built for wetland restoration. The accumulation from hurricanes is sufficient to account for all the inorganic sediments in healthy saltmarsh wetlands.

  2. Surface snow chemistry across Antarctic wind glaze and antidune fields

    NASA Astrophysics Data System (ADS)

    Dixon, D. A.; Mayewski, P. A.; Korotkikh, E.; Sneed, S. B.; Handley, M.; Introne, D.; Scambos, T. A.

    2011-12-01

    This is the first study to measure more than 25 chemical constituents in the surface snow and firn across extensive regions of Antarctica. We present major ion, trace element, heavy metal, rare earth element and oxygen isotope data from a series of surface snow samples and shallow firn sections collected along four US ITASE traverses across East and West Antarctica. In each sample we measure dissolved concentrations of Na+, K+, Mg2+, Ca2+, Cl-, NO3-, SO42-, and MS- using ion chromatography and total concentrations of Sr, Cd, Cs, Ba, La, Ce, Pr, Pb, Bi, U, As, Al, S, Ca, Ti, V, Cr, Mn, Fe, Co, Na, Mg, Li, and K using inductively coupled plasma sector field mass spectrometry. We also measure δ18O by isotope ratio mass spectrometry. The 2002/2003 traverse began at Byrd Surface Camp, West Antarctica, and ended close to South Pole, East Antarctica. The 2003/2004 traverse began at South Pole, passed through AGO4 in central East Antarctica before turning north and finishing at Taylor Dome. The combined 2006/2007 and 2007/2008 traverses started out at Taylor Dome and headed south, passing through the Byrd Glacier drainage basin and ending at South Pole. In this study, we utilize satellite remote sensing measurements of microwave backscatter and grain size to assist in the identification of glaze/dune areas across Antarctica and show how chemical concentrations are higher in these areas, precluding them from containing useful high-resolution chemical climate records. The majority of the non-glaze/dune samples in this study exhibit similar, or lower, concentrations to those from previous studies. Consequently, the results presented here comprise a conservative baseline for Antarctic surface snow chemical concentrations.

  3. Electromagnetic Simulation of the Near-Field Distribution around a Wind Farm

    DOE PAGES

    Yang, Shang-Te; Ling, Hao

    2013-01-01

    An efficienmore » t approach to compute the near-field distribution around and within a wind farm under plane wave excitation is proposed. To make the problem computationally tractable, several simplifying assumptions are made based on the geometry problem. By comparing the approximations against full-wave simulations at 500 MHz, it is shown that the assumptions do not introduce significant errors into the resulting near-field distribution. The near fields around a 3 × 3 wind farm are computed using the developed methodology at 150 MHz, 500 MHz, and 3 GHz. Both the multipath interference patterns and the forward shadows are predicted by the proposed method.« less

  4. The latitude dependencies of the solar wind. [of interplanetary magnetic field polarity and configurations

    NASA Technical Reports Server (NTRS)

    Rosenberg, R. L.; Winge, C. R., Jr.

    1974-01-01

    The motion of spacecraft following the earth's orbit occurs within the solar latitude range of 7 deg 15 min N on approximately September 7 to 7 deg 15 min S on approximately March 6. The latitude dependencies so far detected within this range have shown that the photospheric dipole-like field of the sun makes very important contributions to the interplanetary magnetic field (IMF) observed near the ecliptic. Changes in geomagnetic activity from even to odd numbered 11-year solar cycles are related to changes in the sun's dipolar field. The north-south IMF component and meridional, nonradial flow are important to a complete understanding of steady-state solar wind dynamics. Coronal conditions must be latitude-dependent in a way that accounts for the observed latitude dependence of the velocity and density of the solar wind.

  5. Thermospheric meridional wind control of equatorial spread F and evening prereversal electric field

    NASA Astrophysics Data System (ADS)

    Abdu, M. A.; Iyer, K. N.; de Medeiros, R. T.; Batista, I. S.; Sobral, J. H. A.

    2006-04-01

    The role of the evening prereversal zonal electric field enhancement (PRE) as conducive to equatorial spread F (ESF)/plasma bubble development versus that of the magnetic meridional wind as a suppressing factor is examined using digital ionosonde data from an equatorial site, Sao Luis (SL), and a low latitude site, Cachoeira Paulista (CP) in Brazil. The evening vertical plasma drift (Vz) over SL is used, together with the F layer peak height (hmF2) over CP, to compute the magnetic meridional wind. The analysis performed for two epochs, that is, March-April of 1999 and 2001, provide consistent evidence that the magnetic meridional wind can negatively influence the ESF development in two ways: (a) by reduced development of the PRE and. (b) by direct suppression of the bubble growth

  6. Wind field measurements for the mitigation of airborne health threats in a complex urban environment

    NASA Astrophysics Data System (ADS)

    Arend, Mark; Santoro, David; Abdelazim, Sameh; Moshary, Fred; Ahmed, Sam

    2009-05-01

    The Department of Homeland Security (DHS) sponsored Urban Dispersion Program (UDP) resulted in the strategic placement of weather instruments in New York City (NYC) and the transition of some instruments to the City College of New York (CCNY) operated NYC MetNet to provide timely and accurate information on "skimming field" winds above city building tops. In order to extend the observational capabilities of the NYC MetNet, a cost effective portable eye safe fiber optic based coherent wind lidar system is currently under development in CCNY laboratories. Wind lidar measurements, coupled with the continuous observations from the NYC MetNet, should support the initialization, feedback and development of plume models that would be used after an initial detection of airborne toxins. An overview of the lidar system design and the NYC MetNet will be given.

  7. The effect of interplanetary magnetic field orientation on the solar wind flux impacting Mercury's surface

    NASA Astrophysics Data System (ADS)

    Varela, J.; Pantellini, F.; Moncuquet, M.

    2015-12-01

    The aim of this paper is to study the plasma flows on the Mercury surface for different interplanetary magnetic field orientations on the day side of the planet. We use a single fluid MHD model in spherical coordinates to simulate the interaction of the solar wind with the Hermean magnetosphere for six solar wind realistic configurations with different magnetic field orientations: Mercury-Sun, Sun-Mercury, aligned with the magnetic axis of Mercury (Northward and Southward) and with the orbital plane perpendicular to the previous cases. In the Mercury-Sun (Sun-Mercury) simulation the Hermean magnetic field is weakened in the South-East (North-East) of the magnetosphere leading to an enhancement of the flows on the South (North) hemisphere. For a Northward (Southward) orientation there is an enhancement (weakening) of the Hermean magnetic field in the nose of the bow shock so the fluxes are reduced and drifted to the poles (enhanced and drifted to the equator). If the solar wind magnetic field is in the orbital plane the magnetosphere is tilted to the West (East) and weakened at the nose of the shock, so the flows are enhanced and drifted to the East (West) in the Northern hemisphere and to the West (East) in the Southern hemisphere.

  8. An Improvement of Fine Scale Wind Field Prediction using WRF/MMIF Models for CALPUFF Application.

    NASA Astrophysics Data System (ADS)

    Kim, A. L.; Koo, Y. S.

    2014-12-01

    Accurate simulation of CALPUFF dispersion modeling is largely dependent on the data sets which are properly resolved in the spatial and temporal evolution of meteorological field on a wide range of scales. The fine scale field wind of 100 m spatial resolution is required for the CALPUFF modeling in the complex terrain near the coastal area. The objective of this paper is to provide information how to calculate the fine scale wind field using recent advances in the meteorological model. The diagnostic model of CALMET has been used to generate fine grid scale wind field by interpolating output of mesoscale prognostic weather models of MM5 (short for Fifth-Generation Penn State/NCAR Mesoscale Model) and WRF (Weather Research and Forecast). The MMIF(The Mesoscale Model Interface Program) interfacial program directly converting WRF meteorological output to formats appropriate for CALPUFF modeling without diagnostic interpolations is recently developed. The modeling comparison between WRF/CALMET and WRF/MMIF was carried out to find out a best way in generating fine wind field in the complex geological conditions. For the WRF/CALMET modeling, WRF model output of 900m grid resolution was provided to CALMET model and CALMET then calculated the fine grid resolution of 100m by diagnostically interpolating the WRF output. For the WRF/MMIF modeling, the WRF model directly calculate the fine grid of 100m and the MMIF program was used to convert WRF data. In order to validate model performance of two methods, simulated variables of meteorological fields were compared with observations at the landfill site near the coast in KOREA. It is found that WRF/MMIF is in better agreement with observations than CALWRF/CALMET in respect to the statics of RMSE and IOA. CALPUFF modeling with landfill emission data of H2S was performed and compared with monitoring data to identify effects on meteorological data on the final outcome of CALPUFF dispersion modeling.

  9. Gravity waves observation of wind field in stratosphere based on a Rayleigh Doppler lidar.

    PubMed

    Zhao, Ruocan; Dou, Xiankang; Sun, Dongsong; Xue, Xianghui; Zheng, Jun; Han, Yuli; Chen, Tingdi; Wang, Guocheng; Zhou, Yingjie

    2016-03-21

    Simultaneous wind and temperature measurements in stratosphere with high time-spatial resolution for gravity waves study are scarce. In this paper we perform wind field gravity waves cases in the stratosphere observed by a mobile Rayleigh Doppler lidar. This lidar system with both wind and temperature measurements were implemented for atmosphere gravity waves research in the altitude region 15-60 km. Observations were carried out for two periods of time: 3 months started from November 4, 2014 in Xinzhou, China (38.425°N,112.729°E) and 2 months started from October 7, 2015 in Jiuquan, China (39.741°N, 98.495°E) . The mesoscale fluctuations of the horizontal wind velocity and the two dimensional spectra analysis of these fluctuations show the presence of dominant oscillatory modes with wavelength of 4-14 km and period of around 10 hours in several cases. The simultaneous temperature observations make it possible to identify gravity wave cases from the relationships between different variables: temperature and horizontal wind. The observed cases demonstrate the Rayleigh Doppler Lidar's capacity to study gravity waves. PMID:27136878

  10. Measurement of Unsteady Aerodynamics Load on the Blade of Field Horizontal Axis Wind Turbine

    NASA Astrophysics Data System (ADS)

    Kamada, Yasunari; Maeda, Takao; Naito, Keita; Ouchi, Yuu; Kozawa, Masayoshi

    This paper describes an experimental field study of the rotor aerodynamics of wind turbines. The test wind turbine is a horizontal axis wind turbine, or: HAWT with a diameter of 10m. The pressure distributions on the rotating blade are measured with multi point pressure transducers. Sectional aerodynamic forces are analyzed from pressure distribution. Blade root moments are measured simultaneously by a pair of strain gauges. The inflow wind is measured by a three component sonic anemometer, the local inflow of the blade section are measured by a pair of 7 hole Pitot tubes. The relation between the aerodynamic moments on the blade root from pressure distribution and the mechanical moment from strain gauges is discussed. The aerodynamic moments are estimated from the sectional aerodynamic forces and show oscillation caused by local wind speed and direction change. The mechanical moment shows similar oscillation to the aerodynamic excepting the short period oscillation of the blade first mode frequency. The fluctuation of the sectional aerodynamic force triggers resonant blade oscillations. Where stall is present along the blade section, the blade's first mode frequency is dominant. Without stall, the rotating frequency is dominant in the blade root moment.

  11. Gravity waves observation of wind field in stratosphere based on a Rayleigh Doppler lidar.

    PubMed

    Zhao, Ruocan; Dou, Xiankang; Sun, Dongsong; Xue, Xianghui; Zheng, Jun; Han, Yuli; Chen, Tingdi; Wang, Guocheng; Zhou, Yingjie

    2016-03-21

    Simultaneous wind and temperature measurements in stratosphere with high time-spatial resolution for gravity waves study are scarce. In this paper we perform wind field gravity waves cases in the stratosphere observed by a mobile Rayleigh Doppler lidar. This lidar system with both wind and temperature measurements were implemented for atmosphere gravity waves research in the altitude region 15-60 km. Observations were carried out for two periods of time: 3 months started from November 4, 2014 in Xinzhou, China (38.425°N,112.729°E) and 2 months started from October 7, 2015 in Jiuquan, China (39.741°N, 98.495°E) . The mesoscale fluctuations of the horizontal wind velocity and the two dimensional spectra analysis of these fluctuations show the presence of dominant oscillatory modes with wavelength of 4-14 km and period of around 10 hours in several cases. The simultaneous temperature observations make it possible to identify gravity wave cases from the relationships between different variables: temperature and horizontal wind. The observed cases demonstrate the Rayleigh Doppler Lidar's capacity to study gravity waves.

  12. Comparison of wind tunnel and field experiments to measure potential deposition of fenpropimorph following volatilisation from treated crops.

    PubMed

    Hassink, Jan; Platz, Klaus; Stadler, Reinhold; Zangmeister, Werner; Fent, Gunnar; Möndel, Martin; Kubiak, Roland

    2007-02-01

    The potential for short-range transport via air, i.e. volatilisation from the area of application and subsequent deposition on adjacent non-target areas, was investigated for the fungicide fenpropimorph in a wind tunnel system and under outdoor conditions in a higher-tier field study. Fenpropimorph 750 g L(-1) EC was applied post-emergence to cereal along with a reference standard lindane EC. Stainless steel containers of water were placed at different distances downwind of the application area to trap volatile residues during a study period of 24 h following application. Meteorological conditions in the wind tunnel as well as on the field were constantly monitored during the study period. The wind tunnel system was a partly standardised system on a semi-field scale, i.e. wind direction and wind speed (2 m s(-1)) were constant, but temperature and humidity varied according to the conditions outside. In the field experiment, the average wind speed over the 24 h study period was 3 m s(-1) and no rainfall occurred. Three different measuring lines were installed on the non-target area beside the treated field to cover potential variations in the wind direction. However, no significant differences were observed since the wind direction was generally constant. Fenpropimorph was detected in minor amounts of 0.01-0.05% of the applied material in the wind tunnel experiment. Even at a distance of 1 m beside the treated field, no significant deposition occurred (0.04% of applied material after 24 h). In the field, less than 0.1% of the applied fenpropimorph was detected at 0 m directly beside the treated field. At 5 m distance the deposition values were below 0.04%, and at 20 m distance about 0.01%. In general, the amounts of deposited fenpropimorph detected in the partly standardised wind tunnel system and the higher-tier field study were in good agreement.

  13. Variation of tidal winds in the ionosphere inferred from geomagnetic SQ field

    NASA Technical Reports Server (NTRS)

    Takeda, M.; Araki, T.

    1985-01-01

    The geomagnetic Sq field is mainly generated by the dynamo action of tidal winds in the ionosphere, and therefore some information can be derived from the variation of the Sq field. The geomagnetic Sq field was analyzed during March 1 to 18, 1980, when the geomagnetic activity was exceptionally low, and the equivalent Sq currents calculated every 2 hours by using the spherical harmonics method. Then additional Sq currents were extracted by subtracting the currents averaged through all days in the period from the original currents at each UT. The change of the instantaneous Sq current system by the above-mentioned method is discussed.

  14. Numerical Investigation of Flow Fields in Inductively Coupled Plasma Wind Tunnels

    NASA Astrophysics Data System (ADS)

    Yu, Minghao; Yusuke, Takahashi; Hisashi, Kihara; Ken-ichi, Abe; Kazuhiko, Yamada; Takashi, Abe

    2014-10-01

    Numerical simulations of 10 kW and 110 kW inductively coupled plasma (ICP) wind tunnels were carried out to study physical properties of the flow inside the ICP torch and vacuum chamber with air as the working gas. Two-dimensional compressible axisymmetric Navier-Stokes (N-S) equations that took into account 11 species and 49 chemical reactions of air, were solved. A heat source model was used to describe the heating phenomenon instead of solving the electromagnetic equations. In the vacuum chamber, a four-temperature model was coupled with N-S equations. Numerical results for the 10 kW ICP wind tunnel are presented and discussed in detail as a representative case. It was found that the plasma flow in the vacuum chamber tended to be in local thermochemical equilibrium. To study the influence of operation conditions on the flow field, simulations were carried out for different chamber pressures and/or input powers. The computational results for the above two ICP wind tunnels were compared with corresponding experimental data. The computational and experimental results agree well, therefore the flow fields of ICP wind tunnels can be clearly understood.

  15. Mechanisms for Secondary Eyewall Formation in Tropical Cyclones: A Case Study of Hurricane Katrina (2005)

    NASA Astrophysics Data System (ADS)

    Garcia-Rivera, J. M.; Lin, Y.

    2013-05-01

    The Weather Research and Forecast (WRF) model is used to simulate the last eyewall replacement cycle (ERC) of Hurricane Katrina (2005) just before it's landfall in the Louisiana coastline. In this study, we pursue a complete understanding of the physics behind the secondary eyewall formation (SEF) in tropical cyclones. The simulation results show the occurrence of the early stages of an ERC in the simulated storm just before landfall. This confirms that with the appropriate set of physics parameterization schemes, grid spacing and initial conditions, the numerical model is able to reproduce ERCs on certain tropical cyclones with no data assimilation or extra data inputs. Strong updrafts are observed to converge in a ring outside the primary eyewall of Hurricane Katrina (2005) suggesting SEF during that period. The increase of divergence outside the primary eyewall with an outer-ring of convergence forming above the boundary layer can be part of the mechanisms that lead to SEF. Also, potential vorticity (PV) field is analyzed for its possible relationship with the development of the secondary eyewall. This detailed study of the pre-ERC events in the inner-core of Hurricane Katrina can build the foundations for testing some of the existing hypotheses for the development of secondary eyewalls leading to new ideas behind their formation.

  16. Filament formation in wind-cloud interactions - I. Spherical clouds in uniform magnetic fields

    NASA Astrophysics Data System (ADS)

    Banda-Barragán, W. E.; Parkin, E. R.; Federrath, C.; Crocker, R. M.; Bicknell, G. V.

    2016-01-01

    Filamentary structures are ubiquitous in the interstellar medium, yet their formation, internal structure, and longevity have not been studied in detail. We report the results from a comprehensive numerical study that investigates the characteristics, formation, and evolution of filaments arising from magnetohydrodynamic interactions between supersonic winds and dense clouds. Here, we improve on previous simulations by utilizing sharper density contrasts and higher numerical resolutions. By following multiple density tracers, we find that material in the envelopes of the clouds is removed and deposited downstream to form filamentary tails, while the cores of the clouds serve as footpoints and late-stage outer layers of these tails. Aspect ratios ≳12, subsonic velocity dispersions ˜0.1-0.3 of the wind sound speed, and magnetic field amplifications ˜100 are found to be characteristic of these filaments. We also report the effects of different magnetic field strengths and orientations. The magnetic field strength regulates vorticity production: sinuous filamentary towers arise in non-magnetic environments, while strong magnetic fields inhibit small-scale perturbations at boundary layers making tails less turbulent. Magnetic field components aligned with the direction of the flow favour the formation of pressure-confined flux ropes inside the tails, whilst transverse components tend to form current sheets. Softening the equation of state to nearly isothermal leads to suppression of dynamical instabilities and further collimation of the tail. Towards the final stages of the evolution, we find that small cloudlets and distorted filaments survive the break-up of the clouds and become entrained in the winds, reaching velocities ˜0.1 of the wind speed.

  17. Centennial record of wind-field variations from a coastal dune (German Bight)

    NASA Astrophysics Data System (ADS)

    Lindhorst, Sebastian; Costas, Iria; Betzler, Christian

    2015-04-01

    We show that coastal wandering dunes bear a valuable climate record on time scales of seasons to years and can provide data on past wind-field variations for regions and/or time spans where no instrumental weather observations exist. To access this archive, we propose a combined approach, integrating sedimentological and geophysical methods. Sedimentary architecture and grain-size properties of a 32 m high parabolic dune on the barrier island Sylt (southern North Sea) were investigated using ground-penetrating radar (GPR) and laser-diffraction particle-size analyzer. A chronostratigraphic framework was established based on a series of historical aerial images covering the time period 1936 to 2009. GPR data reveal the internal sedimentary architecture of the dune with an effective resolution of about 0.3 m. Large inland-dipping foresets, being the result of the predominance of onshore winds, form the building block of the dune. The dune exhibits a complex internal architecture comprising numerous unconformities, i.e. gaps in the sedimentary record, slumps, top-lap geometries and shifting depocenters. Therefore, careful mapping of the dunes architectural elements prior to sediment sampling is essential. Grain-size statistics are based on 4900 samples taken equidistantly in a 245 m long trench parallel to the direction of dune movement. Sedimentological proxy data were calibrated using a time series of instrumental weather observations from a meteorological station, 2 km off the dune. These data reach back until the year 1950. Variations in wind speed are best reflected by the sorting of the grain-size distribution: periods of weaker winds result in better sorted sediments, whereas higher wind speeds yield a wider grain-size spectrum. This approach allows us to present a reconstruction of variations in the strength of onshore directed winds covering approximately the last 100 years. Our data show slightly increased wind speeds at the beginning of the 20th century

  18. Correlation and Taylor scale variability in the interplanetary magnetic field fluctuations as a function of solar wind speed

    NASA Astrophysics Data System (ADS)

    Weygand, James M.; Matthaeus, W. H.; Dasso, S.; Kivelson, M. G.

    2011-08-01

    Simultaneous multiple point measurements of the magnetic field from 11 spacecraft are employed to determine the correlation scale and the magnetic Taylor microscale of the solar wind as functions of the mean magnetic field direction and solar wind speed. We find that the Taylor scale is independent of direction relative to the mean magnetic field in both the slow (<450 km/s) and the fast (>600 km/s) solar wind, but the Taylor scale is longer along the mean magnetic field direction in the intermediate (600 km/s ≥ speed ≥ 450 km/s) solar wind. The correlation scale, on the other hand, varies with angle from the mean magnetic field direction. In the slow solar wind the ratio of the parallel correlation scale to the perpendicular correlation scale is 2.55 ± 0.76, decreases to 2.15 ± 0.18 in the intermediate solar wind, and becomes 0.71 ± 0.29 in the fast solar wind. Thus, solar wind turbulence is anisotropic, dominated by quasi two-dimensional turbulence in both the slow and intermediate solar wind, and by slab type turbulence in the fast solar wind. The correlation and Taylor scales may be used to estimate effective magnetic Reynolds numbers separately for each angular channel. To within the uncertainty, no dependence on the solid angle relative to the mean magnetic field could be identified for the Reynolds number. These results may be useful in magnetohydrodynamic modeling of the solar wind and can contribute to our understanding of solar and galactic cosmic ray diffusion in the heliosphere.

  19. The TurbEFA Field Experiment—Measuring the Influence of a Forest Clearing on the Turbulent Wind Field

    NASA Astrophysics Data System (ADS)

    Queck, Ronald; Bernhofer, Christian; Bienert, Anne; Schlegel, Fabian

    2016-04-01

    Forest ecosystems play an important role in the interaction between the land surface and the atmosphere. Measurements and modelling efforts have revealed significant uncertainties in state-of-the-art flux assessments due to spatial inhomogeneities in the airflow and land surface. Here, a field experiment is used to describe the turbulent flow across a typical Central European forest clearing. A three-dimensional model of the inhomogeneous forest stand was developed using an innovative approach based on terrestrial laser-scanner technology. The comparison of the wind statistics of two measurement campaigns (5 and 12 months long) showed the spatial and temporal representativeness of the ultrasonic anemometer measurements within the canopy. An improved method for the correction of the vertical velocity enables the distinction between the instrumental offsets and the vertical winds due to the inclination of the instrument. Despite a 13 % fraction of deciduous plants within the otherwise evergreen canopy, the effects of phenological seasons on the velocity profiles were small. The data classified according to the wind speed revealed the intermittent nature of recirculating air in the clearing. Furthermore, the development of sub-canopy wind-speed maxima is explained by considering the velocity moments and the momentum equation (including measurements of the local pressure gradient). Clearings deflect the flow downward and feed the sub-canopy flow, i.e., advective fluxes, according to wind speed and, likely, clearing size, whereas local pressure gradients play an important role in the development of sub-canopy flow. The presented dataset is freely available at the project homepage.

  20. The TurbEFA Field Experiment—Measuring the Influence of a Forest Clearing on the Turbulent Wind Field

    NASA Astrophysics Data System (ADS)

    Queck, Ronald; Bernhofer, Christian; Bienert, Anne; Schlegel, Fabian

    2016-09-01

    Forest ecosystems play an important role in the interaction between the land surface and the atmosphere. Measurements and modelling efforts have revealed significant uncertainties in state-of-the-art flux assessments due to spatial inhomogeneities in the airflow and land surface. Here, a field experiment is used to describe the turbulent flow across a typical Central European forest clearing. A three-dimensional model of the inhomogeneous forest stand was developed using an innovative approach based on terrestrial laser-scanner technology. The comparison of the wind statistics of two measurement campaigns (5 and 12 months long) showed the spatial and temporal representativeness of the ultrasonic anemometer measurements within the canopy. An improved method for the correction of the vertical velocity enables the distinction between the instrumental offsets and the vertical winds due to the inclination of the instrument. Despite a 13 % fraction of deciduous plants within the otherwise evergreen canopy, the effects of phenological seasons on the velocity profiles were small. The data classified according to the wind speed revealed the intermittent nature of recirculating air in the clearing. Furthermore, the development of sub-canopy wind-speed maxima is explained by considering the velocity moments and the momentum equation (including measurements of the local pressure gradient). Clearings deflect the flow downward and feed the sub-canopy flow, i.e., advective fluxes, according to wind speed and, likely, clearing size, whereas local pressure gradients play an important role in the development of sub-canopy flow. The presented dataset is freely available at the project homepage.

  1. Constraints on the surface magnetic fields of hot stars with winds

    NASA Astrophysics Data System (ADS)

    Maheswaran, Murugesapillai; Cassinelli, Joseph P.

    1992-02-01

    The present study discusses several constraints on the surface magnetic fields of rotating stars with winds. It is shown that there are two allowed ranges for the strengths of surface radial magnetic fields, which are called the 'strong field' and 'weak field' ranges. Attention is given to rotating hot stars with winds and weaker surface magnetic fields. Constraints on rotation and magnetic fields are derived in relation to the extreme case when the equatorial rotation speed approaches the critical rotation. For the O-type main-sequence star 9 Sgr and the B supergiant star Zeta-1 Sco, the upper bound for a weak field is found to be of order 1 G, which is consistent with recent interpretations of radio observations. For a Wolf-Rayet star, with stellar parameters similar to those of CV Ser, it is found to be about 20 G, at faster rotation speeds. From the requirement of hydrostatic equilibrium in the interior, a condition is derived for a star to be an 'extreme magnetic rotator', which is similar to the Eddington limit for stars with radiative forces.

  2. Steady hydromagnetic flows in open magnetic fields. I - A class of analytic solutions. [for stellar winds

    NASA Technical Reports Server (NTRS)

    Low, B. C.; Tsinganos, K.

    1986-01-01

    In the case of an establishment of theoretical models of the hydromagnetic solar wind, the inclusion of the effects of the magnetic field in the solar wind makes it extremely dificult to solve the mathematical problem. This paper has the objective to present a set of particular analytic solutions. The general formulation of Tsinganos (1982) is used to identify a class of analytic solutions to the equations of steady hydromagnetic flows in spherical coordinates. Flow in an open magnetic field are studied, taking into account the problem in dimensionless form, the special case of radial flows with alpha = 0, general radial flows, illustrative examples for flows in which alpha is not equal to 0, a parametric study of nonradial flows in which alpha is not equal to zero, variations in the parameter nu, and variations in the initial speed eta.

  3. Proton fire hose instabilities in the expanding solar wind: Role of oblique magnetic field

    NASA Astrophysics Data System (ADS)

    Hellinger, Petr

    2016-04-01

    The double adiabatic (CGL) approximation for the ideal (Parker) interplanetary magnetic field (IMF) predicts generation of the parallel particle temperature anisotropy (T∥ > T⊥) for a nearly radial magnetic field whereas for a strongly oblique IMF generation of the opposite temperature anisotropy is expected. The transition between the two behaviours is expected at around 45o, i.e. around 1 AU in the solar wind in the ecliptic plane. We investigate properties of a proton-electron plasma system in the solar wind using hybrid expanding box simulations starting with an oblique IMF. The simulated system becomes unstable with respect to the parallel and oblique fire hose instabilities and is forced to stay around the corresponding marginal stability. Rotation of the IMF reduces the time system stays near the marginal stability regions and for a strongly transverse IMF the system moves away from the regions unstable with respect to the fire hose instabilities.

  4. Field Test Results of Using a Nacelle-Mounted Lidar for Improving Wind Energy Capture by Reducing Yaw Misalignment (Presentation)

    SciTech Connect

    Fleming, P.; Scholbrock, A.; Wright, A.

    2014-11-01

    Presented at the Nordic Wind Power Conference on November 5, 2014. This presentation describes field-test campaigns performed at the National Wind Technology Center in which lidar technology was used to improve the yaw alignment of the Controls Advanced Research Turbine (CART) 2 and CART3 wind turbines. The campaigns demonstrated that whether by learning a correction function to the nacelle vane, or by controlling yaw directly with the lidar signal, a significant improvement in power capture was demonstrated.

  5. Wind induced interior and far field radiated exterior noise from automobiles

    NASA Astrophysics Data System (ADS)

    Dobrzynski, W.

    Aerodynamically induced interior noise in passenger cars was investigated. Surface pressure and resulting interior noise were measured on a full-scale automobile in wind tunnel tests. Both quantities are interrelated theoretically; corresponding interior noise predictions are compared to measured data. Results show that high surface-pressure originating even from highly localized flow separations on the car-body tend to dominate interior noise. Far field noise radiation from exterior flow/car-body interaction is predicted and compared to measured data.

  6. Remote Sensing of Wind Fields and Aerosol Distribution with Airborne Scanning Doppler Lidar

    NASA Technical Reports Server (NTRS)

    Rothermel, Jeffry; Cutten, Dean R.; Johnson, Steven C.; Jazembski, Maurice; Arnold, James E. (Technical Monitor)

    2001-01-01

    The coherent Doppler laser radar (lidar), when operated from an airborne platform, is a unique tool for the study of atmospheric and surface processes and features. This is especially true for scientific objectives requiring measurements in optically-clear air, where other remote sensing technologies such as Doppler radar are typically at a disadvantage. The atmospheric lidar remote sensing groups of several US institutions, led by Marshall Space Flight Center, have developed an airborne coherent Doppler lidar capable of mapping the wind field and aerosol structure in three dimensions. The instrument consists of an eye-safe approx. 1 Joule/pulse lidar transceiver, telescope, scanner, inertial measurement unit, and flight computer system to orchestrate all subsystem functions and tasks. The scanner is capable of directing the expanded lidar beam in a variety of ways, in order to extract vertically-resolved wind fields. Horizontal resolution is approx. 1 km; vertical resolution is even finer. Winds are obtained by measuring backscattered, Doppler-shifted laser radiation from naturally-occurring aerosol particles (of order 1 micron diameter). Measurement coverage depends on aerosol spatial distribution and composition. Velocity accuracy has been verified to be approx. 1 meter per second. A variety of applications have been demonstrated during the three flight campaigns conducted during 1995-1998. Examples will be shown during the presentation. In 1995, boundary layer winds over the ocean were mapped with unprecedented resolution. In 1996, unique measurements were made of. flow over the complex terrain of the Aleutian Islands; interaction of the marine boundary layer jet with the California coastal mountain range; a weak dry line in Texas - New Mexico; the angular dependence of sea surface scattering; and in-flight radiometric calibration using the surface of White Sands National Monument. In 1998, the first measurements of eyewall and boundary layer winds within a

  7. Remote Sensing of Wind Fields and Aerosol Distributions with Airborne Scanning Doppler Lidar

    NASA Technical Reports Server (NTRS)

    Rothermel, Jeffry; Cutten, Dean R.; Goodman, H. Michael (Technical Monitor)

    2000-01-01

    The coherent Doppler lidar, when operated from an airborne platform, offers a unique measurement capability for study of atmospheric and surface processes and feature. This is especially true for scientific objectives requiring measurements in optically-clear air, where other remote sensing technologies such as Doppler radar are at a disadvantage in terms of spatial resolution and coverage. The atmospheric lidar remote sensing groups of several US institutions, led by Marshall Space Flight Center, have developed an airborne coherent Doppler lidar capable of mapping the wind field and aerosol structure in three dimensions. The instrument consists of about a 1 Joule/pulse (eyesafe) lidar transceiver, telescope, scanner, inertial measurement unit, and operations control system to orchestrate all subsystem functions and tasks. The scanner is capable of directing the expanded lidar beam in a variety of ways, in order to extract vertically resolved wind fields. Horizontal resolution is about 1 km; vertical resolution is even finer. Winds are obtained by measuring backscattered, Doppler-shifted laser radiation from naturally-occurring aerosol particles (on an order of 1 micron in diameter). Measurement coverage depends on aerosol spatial distribution and concentration. Velocity accuracy has been verified to be about 1 m/s. A variety of applications has been demonstrated during the three flight campaigns conducted during 1995-1998. Examples will be shown during the presentation. In 1995, boundary layer winds over the ocean were mapped with unprecedented resolution. In 1996, unique measurements were made of flow over the complex terrain of the Aleutian Islands; interaction of the marine boundary layer jet with the California coastal mountain range; a weak dry line in Texas - New Mexico; an upper tropospheric jet stream; the angular dependence of sea surface scattering; and in-flight radiometric calibration using the surface of White Sands National Monument. In 1998, the

  8. The dependence of solar wind ion entry on the direction of the interplanetary magnetic field

    NASA Astrophysics Data System (ADS)

    Peroomian, V.

    2003-04-01

    We have investigated the entry characteristics of solar wind ions into the magnetosphere by tracing particle orbits in time-dependent electric and magnetic fields obtained from a three-dimensional global magnetohydrodynamic (MHD) simulation of the magnetosphere. The MHD simulation used in the study began with a 2-hour period of northward interplanetary magnetic field (IMF). The IMF then rotated by 45^o every two hours. The final four hours of the simulation had southward IMF. Millions of ions were launched in the solar wind, upstream of the bowshock, at x = 17 R_E, at time intervals corresponding to the midpoint of each IMF interval and collected after crossing the magnetopause current layer. We found that the region of the upstream solar wind that mapped to the magnetopause entry regions was parallel to the y z orientation of the IMF. Moreover, ions entry into the magnetosphere was in general agreement with the regions identified by Luhmann et al. [1984]. However, there were significant asymmetries in the entry locations due to the direction of the interplanetary electric field and the acceleration experienced by ions in crossing the magnetopause current layer. In all cases the ions entering the magnetosphere did so in sufficient numbers to account for the plasma observed within that region and successfully populated the plasma sheet and ring current regions.

  9. Monitoring tropical cyclone intensity using wind fields derived from short-interval satellite images

    NASA Technical Reports Server (NTRS)

    Rodgers, E. B.; Gentry, R. C.

    1981-01-01

    Rapid scan visible images from the Visible Infrared Spin Scan Radiometer sensor on board SMS-2 and GOES-1 were used to derive high resolution upper and lower tropospheric environmental wind fields around three western Atlantic tropical cyclones (1975-78). These wind fields were used to derive upper and lower tropospheric areal mean relative vorticity and their differences, the net relative angular momentum balance and upper tropospheric mass outflow. These kinematic parameters were shown by studies using composite rawinsonde data to be strongly related to tropical cyclone formation and intensity changes. Also, the role of forced synoptic scale subsidence in tropical cyclone formation was examined. The studies showed that satellite-derived lower and upper tropospheric wind fields can be used to monitor and possibly predict tropical cyclone formation and intensity changes. These kinematic analyses showed that future changes in tropical cyclone intensity are mainly related to the "spin-up" of the storms by the net horizontal transport of relative angular momentum caused by convergence of cyclonic vorticity in the lower troposphere and to a lesser extent the divergence of anticyclone vorticity in the upper troposphere.

  10. Change in distribution and composition of vegetated habitats on Horn Island, Mississippi, northern Gulf of Mexico, in the initial five years following Hurricane Katrina

    NASA Astrophysics Data System (ADS)

    Lucas, K. L.; Carter, G. A.

    2013-10-01

    In the northern Gulf of Mexico, sudden alterations to barrier islands occur relatively often as a result of hurricanes. Barrier island vegetation is affected by storm impacts, such as burial under sand overwash and direct removal by erosion, and also by wind-driven salt spray and flooding by saltwater tidal surge. This study utilized field surveys in conjunction with remotely-sensed data to evaluate changes in the composition and distribution of vegetation on Horn Island, Mississippi, U.S.A., in the initial five years after Hurricane Katrina. The majority of habitat change occurred closer to the shoreline and in areas of overwash. Habitat change was most often associated with an adjustment to higher-elevation plant communities at the expense of wetlands. In addition, substantial tree and shrub mortality as a result of wind, storm surge, salt-spray, and saltwater flooding reduced maritime forest and stable dune habitat, decreasing habitat stability and ecosystem maturity. The lag time in vegetation establishment and foredune development following the storm allowed for sediment transport into back-barrier habitats. Thus, postponing restoration efforts, such as dune plantings or fencing, until at least one full growing season has elapsed following a hurricane may provide back-barrier habitats with the sediment deposition needed to offset sea-level rise and subsidence.

  11. Predictability of dune activity in real dune fields under unidirectional wind regimes

    NASA Astrophysics Data System (ADS)

    Barchyn, Thomas E.; Hugenholtz, Chris H.

    2015-02-01

    We present an analysis of 10 dune fields to test a model-derived hypothesis of dune field activity. The hypothesis suggests that a quantifiable threshold exists for stabilization in unidirectional wind regimes: active dunes have slipface deposition rates that exceed the vegetation deposition tolerance, and stabilizing dunes have the opposite. We quantified aeolian sand flux, slipface geometry, and vegetation deposition tolerance to directly test the hypothesis at four dune fields (Bigstick, White Sands Stable, White Sands Active, and Cape Cod). We indirectly tested the hypothesis at six additional dune fields with limited vegetation data (Hanford, Año Nuevo, Skagen Odde, Salton Sea, Oceano Stable, and Oceano Active, "inverse calculation sites"). We used digital topographic data and estimates of aeolian sand flux to approximate the slipface deposition rates prior to stabilization. Results revealed a distinct, quantifiable, and consistent pattern despite diverse environmental conditions: the modal peak of prestabilization slipface deposition rates was 80% of the vegetation deposition tolerance at stabilized or stabilizing dune fields. Results from inverse calculation sites indicate deposition rates at stabilized sites were near a hypothesized maximum vegetation deposition tolerance (1 m a-1), and active sites had slipface deposition rates much higher. Overall, these results confirm the hypothesis and provide evidence of a globally applicable, simple, and previously unidentified predictor for the dynamics of vegetation cover in dune fields under unidirectional wind regimes.

  12. Assessing Hurricane Katrina Vegetation Damage at Stennis Space Center using IKONOS Image Classification Techniques

    NASA Technical Reports Server (NTRS)

    Spruce, Joseph P.; Ross, Kenton W.; Graham, William D.

    2007-01-01

    Hurricane Katrina hit southwestern Mississippi on August 29, 2005, at 9:45 a.m. CDT as a category 3 storm with surges up to approx. 9 m and sustained winds of approx. 120 mph. The hurricane's wind, rain, and flooding devastated several coastal towns, from New Orleans through Mobile. The storm also caused significant damage to infrastructure and vegetation of NASA's SSC (Stennis Space Center). Storm recovery at SSC involved not only repairs of critical infrastructure but also forest damage mitigation (via timber harvests and control burns to reduce fire risk). This presentation discusses an effort to use commercially available high spatial resolution multispectral IKONOS data for vegetation damage assessment, based on data collected over SSC on September 2, 2005.

  13. ENVIRONMENTAL SAMPLING AND ANALYSIS IN THE AFTERMATH OF HURRICANE KATRINA

    EPA Science Inventory

    This presentation describes the environmental sampling completed by EPA in southeastern Louisiana after Hurricane Katrina caused major catastrophic damage. Presentation also describes EPA's Environmental Unit activities in Baton Rouge and New Orleans, LA, and Dallas, TX.

  14. Genetics Experts Unite to I.D. Unknown Katrina Victims

    MedlinePlus

    ... Current Issue Past Issues Research News From NIH Genetics Experts Unite to I.D. Unknown Katrina Victims ... in the recent Advances in molecular biology and genetics," says team member Stephen Sherry, Ph.D., of ...

  15. EMERGENCY RESPONSE FOR PUBLIC WATER SUPPLIES AFTER HURRICANE KATRINA

    EPA Science Inventory

    Hurricane Katrina resulted in damage and destruction to local water supplies in Mississippi and Louisiana affecting millions of people. Immediately following the devastation, a multidisciplinary team of 30 EPA emergency response, research, and water program personnel joined force...

  16. Children and Trauma: A Post-Katrina and Rita Response

    ERIC Educational Resources Information Center

    Hebert, Barbara B.; Ballard, Mary B.

    2007-01-01

    Many children have struggled to cope with the traumatic experiences brought about by hurricanes Katrina and Rita. This article recounts how the authors intervened in the lives of children and families after the storms. (Contains 3 figures.)

  17. Consequences of the large ambipolar electric field in the solar wind

    SciTech Connect

    Scudder, J.D.

    1995-06-01

    The parallel electric field in the solar wind is much smaller than the V x B motional electric field, yet in the proper dimensions units it is very `large`. At the orbit of earth it is within a few percent of being at the Dreicer limit. This `large` electric field is required for quasi-neutrality; it will be shown to have interesting consequences for the electron velocity distribution function and the description of transport of heat. Interestingly, a similar dimensionless situation also occurs at the base of the transition region, while below the transition region the dimensionless electric field is very weak. These facts suggest a new way to look at the thermal-suprathermal dichotomy in velocity distributions as the response of a plasma where charge neutrality requires such large dimensionless electric fields.

  18. In situ magnetic field measurements during AMPTE solar wind Li/sup +/ releases

    SciTech Connect

    Luehr, H.; Southwood, D.J.; Kloecker, N.; Acuna, M.; Haeusler, B.; Dunlop, M.W.; Mier-Jedrzejowicz, W.A.C.; Rijnbeek, R.P.; Six, M.

    1986-02-01

    Data recorded by the magnetometers on the German (IRM) and British (UKS) spacecraft of the Active Magnetospheric Particle Tracer Explorers (AMPTE) spacecraft mission are described during the immediate period following the two releases of lithium from the IRM during September. Ions created in the first seconds of the release form a coherent obstacle to solar wind flow. A cavity from which the interplanetary magnetic field is excluded is detected. Outside the cavity the field is compressed, and subsequently the cavity is convected downstream. We compare what is observed with other relevant natural interactions but also emphasize the unique features of this experiment.

  19. New Models of Solar Wind Acceleration and Stream Interactions in the Sun's Topologically Complex Magnetic Field

    NASA Astrophysics Data System (ADS)

    Cranmer, S. R.; Van Ballegooijen, A. A.; Woolsey, L. N.

    2012-12-01

    The last decade has seen significant progress toward identifying and characterizing the processes that heat the corona and accelerate the solar wind. It is believed that the low-speed solar wind comes from a wide range of source regions in the corona, including streamers, pseudostreamers, active regions, and small coronal holes. These source regions tend to be associated with the most topologically complex magnetic fields, and it is unclear how the coronal field lines connect to the large-scale open heliospheric field. To learn more about these connections, we present new models of turbulence-driven coronal heating and solar wind acceleration along empirically constrained field lines. To begin, we chose a time period during which the footpoints linked to the ecliptic plane were rooted in Quiet Sun (QS) regions away from both large coronal holes and strong-field active regions. The weak and mixed-polarity QS field was observed at high resolution by the VSM instrument of SOLIS, and we extrapolated this field into the corona using the potential field source surface method. Time-steady 1D models of individual flux tubes were created with the ZEPHYR code (Cranmer et al. 2007) that solves the one-fluid equations of mass, momentum, and energy conservation from the photosphere to 4 AU. Then, to take account of stream-stream interactions between the flux tubes, we solved a 2D time-steady set of MHD conservation equations to determine the corotating longitudinal structure in the ecliptic plane. We aim to understand the extent to which fine-scale inter-tube plasma structures in the corona survive to large distances. In other words, we want to know how much of the coronal flux tube "spaghetti" is either shredded by turbulence or smeared out by stream interactions. We also plan to evaluate the level of high-resolution detail that is needed in coronal flux tube modeling in order to accurately predict the space weather consequences of various kinds of corotating structures in the

  20. Magnetic Field-line Length and Twist Distributions within Interplanetary Flux Fopes from Wind Spacecraft Measurements

    NASA Astrophysics Data System (ADS)

    Hu, Q.; Qiu, J.; Krucker, S.; Wang, L.; Wang, B.; Chen, Y.; Moestl, C.

    2014-12-01

    We report on the detailed and systematic study of field-line twist and length distributions within magnetic flux ropes embedded in Interplanetary Coronal Mass Ejections (ICMEs). In particular we will utilize energetic electron burst observations at 1 AU together with associated type III radio emissions detected by the Wind spacecraft to provide unique measurements of magnetic field-line lengths within selected ICME events. These direct measurements will be compared with flux-rope model calculations to help assess the fidelity of different models and to provide diagnostics of internal structures. The Grad-Shafranov reconstruction method will be utilized together with a constant-twist nonlinear force-free (Gold-Hoyle) flux rope model and the commonly known Lundquist (linear force-free) model to reveal the close relation between the field-line twist and length in cylindrical flux ropes, based on in-situ Wind spacecraft magnetic field and plasma measurements. We show that our initial analysis of field-line twist indicates clear deviation from the Lundquist model, but better consistency with the Gold-Hoyle model. We will also discuss the implications of our analysis of flux-rope structures on the origination and evolution processes in their corresponding solar source regions.

  1. Measurement uncertainties in quantifying aeolian mass flux: evidence from wind tunnel and field site data

    PubMed Central

    Keijsers, Joep G.S.; Maroulis, Jerry; Visser, Saskia M.

    2014-01-01

    Aeolian sediment traps are widely used to estimate the total volume of wind-driven sediment transport, but also to study the vertical mass distribution of a saltating sand cloud. The reliability of sediment flux estimations from such measurements are dependent upon the specific configuration of the measurement compartments and the analysis approach used. In this study, we analyse the uncertainty of these measurements by investigating the vertical cumulative distribution and relative sediment flux derived from both wind tunnel and field studies. Vertical flux data was examined using existing data in combination with a newly acquired dataset; comprising meteorological data and sediment fluxes from six different events, using three customized catchers at Ameland beaches in northern Netherlands. Fast-temporal data collected in a wind tunnel shows that the median transport height has a scattered pattern between impact and fluid threshold, that increases linearly with shear velocities above the fluid threshold. For finer sediment, a larger proportion was transported closer to the surface compared to coarser sediment fractions. It was also shown that errors originating from the distribution of sampling compartments, specifically the location of the lowest sediment trap relative to the surface, can be identified using the relative sediment flux. In the field, surface conditions such as surface moisture, surface crusts or frozen surfaces have a more pronounced but localized effect than shear velocity. Uncertainty in aeolian mass flux estimates can be reduced by placing multiple compartments in closer proximity to the surface. PMID:25071984

  2. Prediction of far-field wind turbine noise propagation with parabolic equation.

    PubMed

    Lee, Seongkyu; Lee, Dongjai; Honhoff, Saskia

    2016-08-01

    Sound propagation of wind farms is typically simulated by the use of engineering tools that are neglecting some atmospheric conditions and terrain effects. Wind and temperature profiles, however, can affect the propagation of sound and thus the perceived sound in the far field. A better understanding and application of those effects would allow a more optimized farm operation towards meeting noise regulations and optimizing energy yield. This paper presents the parabolic equation (PE) model development for accurate wind turbine noise propagation. The model is validated against analytic solutions for a uniform sound speed profile, benchmark problems for nonuniform sound speed profiles, and field sound test data for real environmental acoustics. It is shown that PE provides good agreement with the measured data, except upwind propagation cases in which turbulence scattering is important. Finally, the PE model uses computational fluid dynamics results as input to accurately predict sound propagation for complex flows such as wake flows. It is demonstrated that wake flows significantly modify the sound propagation characteristics.

  3. Prediction of far-field wind turbine noise propagation with parabolic equation.

    PubMed

    Lee, Seongkyu; Lee, Dongjai; Honhoff, Saskia

    2016-08-01

    Sound propagation of wind farms is typically simulated by the use of engineering tools that are neglecting some atmospheric conditions and terrain effects. Wind and temperature profiles, however, can affect the propagation of sound and thus the perceived sound in the far field. A better understanding and application of those effects would allow a more optimized farm operation towards meeting noise regulations and optimizing energy yield. This paper presents the parabolic equation (PE) model development for accurate wind turbine noise propagation. The model is validated against analytic solutions for a uniform sound speed profile, benchmark problems for nonuniform sound speed profiles, and field sound test data for real environmental acoustics. It is shown that PE provides good agreement with the measured data, except upwind propagation cases in which turbulence scattering is important. Finally, the PE model uses computational fluid dynamics results as input to accurately predict sound propagation for complex flows such as wake flows. It is demonstrated that wake flows significantly modify the sound propagation characteristics. PMID:27586709

  4. Interplanetary gas. XXV - A solar wind and interplanetary magnetic field interpretation of cometary light outbursts

    NASA Technical Reports Server (NTRS)

    Niedner, M. B., Jr.

    1980-01-01

    Possible relationships of cometary brightness outbursts with the solar wind and interplanetary magnetic field are examined. Two types of outburst are distinguished: those which involve a significant brightening of both the head and the tail in a comet with a conspicuous plasma tail (Class I), and those involving the brightening of the central condensation of a previously faint comet with no detectable plasma tail (Class II). Class I bursts, as exemplified by Comet Morehouse 1908c, are attributed to the generation in the head of enhanced amounts of ions and their injection into the tail shortly before it disconnects, with ionization provided by sector boundary crossings. Class II events, as exhibited by Comet P/Tuttle-Giacobini-Kresak 1973b, are interpreted as the result of the bombardment of the nucleus by disturbed solar wind near corotated high-speed streams and sector boundaries, leading to highly exothermic chemical reactions.

  5. Formation of lunar swirls by magnetic field standoff of the solar wind.

    PubMed

    Glotch, Timothy D; Bandfield, Joshua L; Lucey, Paul G; Hayne, Paul O; Greenhagen, Benjamin T; Arnold, Jessica A; Ghent, Rebecca R; Paige, David A

    2015-01-01

    Lunar swirls are high-albedo markings on the Moon that occur in both mare and highland terrains; their origin remains a point of contention. Here, we use data from the Lunar Reconnaissance Orbiter Diviner Lunar Radiometer to support the hypothesis that the swirls are formed as a result of deflection of the solar wind by local magnetic fields. Thermal infrared data from this instrument display an anomaly in the position of the silicate Christiansen Feature consistent with reduced space weathering. These data also show that swirl regions are not thermophysically anomalous, which strongly constrains their formation mechanism. The results of this study indicate that either solar wind sputtering and implantation are more important than micrometeoroid bombardment in the space-weathering process, or that micrometeoroid bombardment is a necessary but not sufficient process in space weathering, which occurs on airless bodies throughout the solar system. PMID:25650225

  6. Controlled field experiments of wind effects on thermal signatures of buried and surface-laid landmines

    NASA Astrophysics Data System (ADS)

    van Dam, Remke L.; Borchers, Brian; Hendrickx, Jan M.; Hong, Sung

    2004-09-01

    Thermal signatures of buried land mines depend on a complex combination of environmental conditions, soil properties, and properties and burial depth of the land mine. Due to the complex nature of the problem most modeling and experimental efforts to understand thermal signatures of land mines have focused on the effects of one or a few variables. Of these variables, the effect of wind speed has received little attention in modeling and experimental studies. In this contribution we discuss the role of wind in the generation of thermal images and we present results of field experiments at the outdoor land mine detection test facility at New Mexico Tech. Here, several anti-tank and anti-personnel land mine simulants have been buried in sand, loam, and clay soils. During the measurements the environmental and soil conditions were continuously monitored using a fully equipped weather station and using probes for measurements of soil temperature and soil water content.

  7. Inferring Near-Surface Tornado Wind Fields from Simulated Surface Marks

    NASA Astrophysics Data System (ADS)

    Zimmerman, Michael; Lewellen, David

    2010-02-01

    In 1967, T. T. Fujita proposed estimating tornado wind speeds from various classes of surface marks left behind by translating, debris-laden tornadoes. Here we revisit this approach by merits of Fujita's idea in the context of simulated surface marks, after decades of inactivity by the scientific community. We employ large eddy simulations of tornadoes with fully-coupled, sand-like debris that may be lofted from and redeposited to the surface. The resulting patterns of debris removal and deposition are convolutions of events in space and time that contain information about the wind fields that created them. The most prominent marks are insensitive to modest changes in the parameterizations employed. We extend Fujita's original treatment of surface marks to encompass more general families of marks, inferring near-surface flow velocities and spatial scales in different types of simulated tornadoes. Finally, we show how our methods and results could be applied to improve interpretations of observational data. )

  8. A simple method to estimate threshold friction velocity of wind erosion in the field

    NASA Astrophysics Data System (ADS)

    Li, Junran; Okin, Gregory S.; Herrick, Jeffrey E.; Belnap, Jayne; Munson, Seth M.; Miller, Mark E.

    2010-05-01

    This study provides a fast and easy-to-apply method to estimate threshold friction velocity (TFV) of wind erosion in the field. Wind tunnel experiments and a variety of ground measurements including air gun, pocket penetrometer, torvane, and roughness chain were conducted in Moab, Utah and cross-validated in the Mojave Desert, California. Patterns between TFV and ground measurements were examined to identify the optimum method for estimating TFV. The results show that TFVs were best predicted using the air gun and penetrometer measurements in the Moab sites. This empirical method, however, systematically underestimated TFVs in the Mojave Desert sites. Further analysis showed that TFVs in the Mojave sites can be satisfactorily estimated with a correction for rock cover, which is presumably the main cause of the underestimation of TFVs. The proposed method may be also applied to estimate TFVs in environments where other non-erodible elements such as postharvest residuals are found.

  9. Formation of lunar swirls by magnetic field standoff of the solar wind.

    PubMed

    Glotch, Timothy D; Bandfield, Joshua L; Lucey, Paul G; Hayne, Paul O; Greenhagen, Benjamin T; Arnold, Jessica A; Ghent, Rebecca R; Paige, David A

    2015-02-04

    Lunar swirls are high-albedo markings on the Moon that occur in both mare and highland terrains; their origin remains a point of contention. Here, we use data from the Lunar Reconnaissance Orbiter Diviner Lunar Radiometer to support the hypothesis that the swirls are formed as a result of deflection of the solar wind by local magnetic fields. Thermal infrared data from this instrument display an anomaly in the position of the silicate Christiansen Feature consistent with reduced space weathering. These data also show that swirl regions are not thermophysically anomalous, which strongly constrains their formation mechanism. The results of this study indicate that either solar wind sputtering and implantation are more important than micrometeoroid bombardment in the space-weathering process, or that micrometeoroid bombardment is a necessary but not sufficient process in space weathering, which occurs on airless bodies throughout the solar system.

  10. Comparison of computational modelling and field testing of a small wind turbine operating in unsteady flows

    NASA Astrophysics Data System (ADS)

    Bradney, D. R.; Evans, S. P.; Salles Pereira Da Costa, M.; Clausen, P. D.

    2016-09-01

    Small horizontal-axis wind turbines are likely to operate in a broad range of operating flow conditions, often in highly turbulent flow, due, in part, to their varied site placements. This paper compares the computational simulations of the performance of a 5 kW horizontal-axis wind turbine to detailed field measurements, with a particular focus on the impact of unsteady operating conditions on the drivetrain performance and generator output. Results indicate that the current Blade Element Momentum Theory based aerodynamic models under-predict the effect of high turbine yaw on the rotor torque, leading to a difference between predicted and measured shaft speed and power production. Furthermore, the results show discrepancies between the predicted instantaneous turbine yaw performance and measurements.

  11. The use of wind fields in a land use regression model to predict air pollution concentrations for health exposure studies

    NASA Astrophysics Data System (ADS)

    Arain, M. A.; Blair, R.; Finkelstein, N.; Brook, J. R.; Sahsuvaroglu, T.; Beckerman, B.; Zhang, L.; Jerrett, M.

    A methodology is developed to include wind flow effects in land use regression (LUR) models for predicting nitrogen dioxide (NO 2) concentrations for health exposure studies. NO 2 is widely used in health studies as an indicator of traffic-generated air pollution in urban areas. Incorporation of high-resolution interpolated observed wind direction from a network of 38 weather stations in a LUR model improved NO 2 concentration estimates in densely populated, high traffic and industrial/business areas in Toronto-Hamilton urban airshed (THUA) of Ontario, Canada. These small-area variations in air pollution concentrations that are probably more important for health exposure studies may not be detected by sparse continuous air pollution monitoring network or conventional interpolation methods. Observed wind fields were also compared with wind fields generated by Global Environmental Multiscale-High resolution Model Application Project (GEM-HiMAP) to explore the feasibility of using regional weather forecasting model simulated wind fields in LUR models when observed data are either sparse or not available. While GEM-HiMAP predicted wind fields well at large scales, it was unable to resolve wind flow patterns at smaller scales. These results suggest caution and careful evaluation of regional weather forecasting model simulated wind fields before incorporating into human exposure models for health studies. This study has demonstrated that wind fields may be integrated into the land use regression framework. Such integration has a discernable influence on both the overall model prediction and perhaps more importantly for health effects assessment on the relative spatial distribution of traffic pollution throughout the THUA. Methodology developed in this study may be applied in other large urban areas across the world.

  12. Extracting full-field dynamic strain response of a rotating wind turbine using photogrammetry

    NASA Astrophysics Data System (ADS)

    Baqersad, Javad; Poozesh, Peyman; Niezrecki, Christopher; Avitabile, Peter

    2015-04-01

    Health monitoring of wind turbines is typically performed using conventional sensors (e.g. strain-gages and accelerometers) that are usually mounted to the nacelle or gearbox. Although many wind turbines stop operating due to blade failures, there are typically few to no sensor mounted on the blades. Placing sensors on the rotating parts of the structure is a challenge due to the wiring and data transmission constraints. Within the current work, an approach to monitor full-field dynamic response of rotating structures (e.g. wind turbine blades or helicopter rotors) is developed and experimentally verified. A wind turbine rotor was used as the test structure and was mounted to a block and horizontally placed on the ground. A pair of bearings connected to the rotor shaft allowed the turbine to freely spin along the shaft. Several optical targets were mounted to the blades and a pair of high-speed cameras was used to monitor the dynamics of the spinning turbine. Displacements of the targets during rotation were measured using three-dimensional point tracking. The point tracking technique measured both rigid body displacement and flexible deformation of the blades at target locations. While the structure is rotating, only flap displacements of optical targets (displacements out of the rotation plane) were used in strain prediction process. The measured displacements were expanded and applied to the finite element model of the turbine to extract full-field dynamic strain on the structure. The proposed approach enabled the prediction of dynamic response on the outer surface as well as within the inner points of the structure where no other sensor could be easily mounted. In order to validate the proposed approach, the predicted strain was compared to strain measured at four locations on the spinning blades using a wireless strain-gage system.

  13. Simulation of the low latitude ionosphere response to disturbed winds and electric fields: Brazilian region

    NASA Astrophysics Data System (ADS)

    Batista, Inez S.; Souza, Jonas; Bailey, Graham; Bravo, Manuel

    2016-07-01

    Modeling the ionosphere during disturbed periods is one of the most challenging tasks due to the complexity of the phenomena that affect the electric fields and the thermosphere environment as whole. It is well known that depending on the direction of the interplanetary magnetic field disturbance electric fields (undershielding or overshielding) can penetrate from high to low latitudes causing significant disturbances in the electron density distribution and in the equatorial ionization anomaly (EIA) development. Besides that, the large amount of energy deposited in the polar region during disturbed periods will be responsible for the generation of disturbed winds that will flow towards the equator where they produce a disturbance dynamo which also affects the EIA density distribution. The TIDs and TADs are also sources of disturbances that propagate at high velocity reaching the equator 2-3 hours after the beginning of the magnetic storm. In this work we use the Sheffield University Plasmasphere-Ionosphere Model at INPE (SUPIM-INPE), to simulate the drastic effects that were observed at the low latitude ionosphere in the Brazilian region during a very intense magnetic storm event. A few models are tested for the disturbed electric field and wind. The simulation results showed that the observations are better explained when considering a traveling waveform disturbance propagating from north to south at a velocity equal to 200 m/s.

  14. Development of Dynamic Flow Field Pressure Probes Suitable for Use in Large Scale Supersonic Wind Tunnels

    NASA Technical Reports Server (NTRS)

    Porro, A. Robert

    2000-01-01

    A series of dynamic flow field pressure probes were developed for use in large-scale supersonic wind tunnels at NASA Glenn Research Center. These flow field probes include pitot, static, and five-hole conical pressure probes that are capable of capturing fast acting flow field pressure transients that occur on a millisecond time scale. The pitot and static probes can be used to determine local Mach number time histories during a transient event. The five-hole conical pressure probes are used primarily to determine local flow angularity, but can also determine local Mach number. These probes were designed, developed, and tested at the NASA Glenn Research Center. They were also used in a NASA Glenn 10-by 10-Foot Supersonic Wind Tunnel (SWT) test program where they successfully acquired flow field pressure data in the vicinity of a propulsion system during an engine compressor staff and inlet unstart transient event. Details of the design, development, and subsequent use of these probes are discussed in this report.

  15. First ever cross comparison of thermospheric wind measured by narrow- and wide-field optical Doppler spectroscopy

    NASA Astrophysics Data System (ADS)

    Dhadly, M. S.; Meriwether, J.; Conde, M.; Hampton, D.

    2015-11-01

    We present the first ever cross comparisons of F region horizontal neutral wind measurements taken using two different types of optical Doppler spectrometer: all-sky scanning Doppler imagers (SDI) and narrow-field Fabry-Perot interferometers (NFPIs). Horizontal neutral winds were inferred using bistatic observations from three NFPIs, together with monostatic and bistatic observations from two SDIs. All instruments were located in Alaska. Cross comparisons were made for a total of seven nights in January and February 2010. The results show a high degree of correlation between the diurnal behaviors of the line-of-sight (LOS) winds measured by both instruments. The SDI and NFPI LOS wind time series also often contained high-frequency fluctuations with similar overall characteristics, strongly suggesting that these fluctuations were geophysical in origin. However, the amplitude of the high-frequency component was stronger in the NFPI LOS wind than in the SDI data. Even the smallest SDI angular resolution element is much larger than the NFPI field of view, suggesting that its relative insensitivity to high frequencies is because these fluctuations are associated with local-scale structures whose spatial extent is smaller than ˜40 km spanned by the smallest SDI viewing field. Upon fitting vectors to the LOS wind data, close agreement was found between the wind components estimated by the two types of instrument. Discrepancies that did arise occurred most often when the neutral wind speed was weak, suggesting that conditions capable of driving higher neutral wind speeds also suppressed the development of small-scale structures in the thermospheric neutral wind fields.

  16. The influences of solar wind pressure and interplanetary magnetic field on global magnetic field and outer radiation belt electrons

    DOE PAGES

    Yu, J.; Li, L. Y.; Cao, J. B.; Reeves, Geoffrey D.; Baker, D. N.; Spence, H.

    2016-07-22

    Using the Van Allen Probe in situ measured magnetic field and electron data, we examine the solar wind dynamic pressure and interplanetary magnetic field (IMF) effects on global magnetic field and outer radiation belt relativistic electrons (≥1.8 MeV). The dynamic pressure enhancements (>2 nPa) cause the dayside magnetic field increase and the nightside magnetic field reduction, whereas the large southward IMFs (Bz-IMF < –2nT) mainly lead to the decrease of the nightside magnetic field. In the dayside increased magnetic field region (magnetic local time (MLT) ~ 06:00–18:00, and L > 4), the pitch angles of relativistic electrons are mainly pancakemore » distributions with a flux peak around 90° (corresponding anisotropic index A > 0.1), and the higher-energy electrons have stronger pancake distributions (the larger A), suggesting that the compression-induced betatron accelerations enhance the dayside pancake distributions. However, in the nighttime decreased magnetic field region (MLT ~ 18:00–06:00, and L ≥ 5), the pitch angles of relativistic electrons become butterfly distributions with two flux peaks around 45° and 135° (A < 0). The spatial range of the nighttime butterfly distributions is almost independent of the relativistic electron energy, but it depends on the magnetic field day-night asymmetry and the interplanetary conditions. The dynamic pressure enhancements can make the nighttime butterfly distribution extend inward. The large southward IMFs can also lead to the azimuthal expansion of the nighttime butterfly distributions. As a result, these variations are consistent with the drift shell splitting and/or magnetopause shadowing effect.« less

  17. The influences of solar wind pressure and interplanetary magnetic field on global magnetic field and outer radiation belt electrons

    NASA Astrophysics Data System (ADS)

    Yu, J.; Li, L. Y.; Cao, J. B.; Reeves, G. D.; Baker, D. N.; Spence, H.

    2016-07-01

    Using the Van Allen Probe in situ measured magnetic field and electron data, we examine the solar wind dynamic pressure and interplanetary magnetic field (IMF) effects on global magnetic field and outer radiation belt relativistic electrons (≥1.8 MeV). The dynamic pressure enhancements (>2 nPa) cause the dayside magnetic field increase and the nightside magnetic field reduction, whereas the large southward IMFs (Bz-IMF < -2nT) mainly lead to the decrease of the nightside magnetic field. In the dayside increased magnetic field region (magnetic local time (MLT) ~ 06:00-18:00, and L > 4), the pitch angles of relativistic electrons are mainly pancake distributions with a flux peak around 90° (corresponding anisotropic index A > 0.1), and the higher-energy electrons have stronger pancake distributions (the larger A), suggesting that the compression-induced betatron accelerations enhance the dayside pancake distributions. However, in the nighttime decreased magnetic field region (MLT ~ 18:00-06:00, and L ≥ 5), the pitch angles of relativistic electrons become butterfly distributions with two flux peaks around 45° and 135° (A < 0). The spatial range of the nighttime butterfly distributions is almost independent of the relativistic electron energy, but it depends on the magnetic field day-night asymmetry and the interplanetary conditions. The dynamic pressure enhancements can make the nighttime butterfly distribution extend inward. The large southward IMFs can also lead to the azimuthal expansion of the nighttime butterfly distributions. These variations are consistent with the drift shell splitting and/or magnetopause shadowing effect.

  18. Remote Sensing Data in Wind Velocity Field Modelling: a Case Study from the Sudetes (SW Poland)

    NASA Astrophysics Data System (ADS)

    Jancewicz, Kacper

    2014-06-01

    The phenomena of wind-field deformation above complex (mountainous) terrain is a popular subject of research related to numerical modelling using GIS techniques. This type of modelling requires, as input data, information on terrain roughness and a digital terrain/elevation model. This information may be provided by remote sensing data. Consequently, its accuracy and spatial resolution may affect the results of modelling. This paper represents an attempt to conduct wind-field modelling in the area of the Śnieżnik Massif (Eastern Sudetes). The modelling process was conducted in WindStation 2.0.10 software (using the computable fluid dynamics solver Canyon). Two different elevation models were used: the Global Land Survey Digital Elevation Model (GLS DEM) and Digital Terrain Elevation Data (DTED) Level 2. The terrain roughness raster was generated on the basis of Corine Land Cover 2006 (CLC 2006) data. The output data were post-processed in ArcInfo 9.3.1 software to achieve a high-quality cartographic presentation. Experimental modelling was conducted for situations from 26 November 2011, 25 May 2012, and 26 May 2012, based on a limited number of field measurements and using parameters of the atmosphere boundary layer derived from the aerological surveys provided by the closest meteorological stations. The model was run in a 100-m and 250-m spatial resolution. In order to verify the model's performance, leave-one-out cross-validation was used. The calculated indices allowed for a comparison with results of former studies pertaining to WindStation's performance. The experiment demonstrated very subtle differences between results in using DTED or GLS DEM elevation data. Additionally, CLC 2006 roughness data provided more noticeable improvements in the model's performance, but only in the resolution corresponding to the original roughness data. The best input data configuration resulted in the following mean values of error measure: root mean squared error of velocity

  19. The Rebirth of Montessori: Rebuilding a Public Charter Montessori School in Post-Katrina New Orleans

    ERIC Educational Resources Information Center

    Selvidge, Ellen

    2008-01-01

    "Pre-Katrina" and "Post-Katrina" are common terms for time frames these days in New Orleans, often reminding me of the BCE/CE timeline distinctions. You hear "Pre-Katrina" and "Post-Katrina" on the news, in the paper, and in everyday conversations. Although more and more people have moved back to New Orleans, businesses and restaurants are open,…

  20. Hurricane Katrina and mental health: a research note on Mississippi Gulf Coast residents.

    PubMed

    Picou, J Steven; Hudson, Kenneth

    2010-01-01

    Katrina was the most devastating and deadliest hurricane in recent U.S. history. The storm was particularly destructive for residents of the Mississippi Gulf Coast where sustained winds of 135 mph and a storm surge of 32 feet literally obliterated the built and modified environments. Limited research exists on the chronic (32 months) mental health impacts of survivors in this geographical area. Random-digit dialing telephone surveys were administered in Harrison and Hancock counties (Mississippi) in April and May 2008 and data were collected on a number of mental health outcomes. The results of the calculation of Oridinary Least Squares (OLS) regression models revealed that females, African Americans, and less-educated residents manifested the most severe mental health impacts. Most important, consistent findings for depression and Katrina-related psychological stress indicate that residents who were separated from family members, had maximum residential damage, and suffered severe financial problems remained significantly impacted 32 months after Katrina’s landfall. A secondary stressor, in the form of having applications to the Mississippi State Grant Program denied or not processed also predicted personal depression. The implications of these findings are discussed.

  1. Hurricane Katrina and mental health: a research note on Mississippi Gulf Coast residents.

    PubMed

    Picou, J Steven; Hudson, Kenneth

    2010-01-01

    Katrina was the most devastating and deadliest hurricane in recent U.S. history. The storm was particularly destructive for residents of the Mississippi Gulf Coast where sustained winds of 135 mph and a storm surge of 32 feet literally obliterated the built and modified environments. Limited research exists on the chronic (32 months) mental health impacts of survivors in this geographical area. Random-digit dialing telephone surveys were administered in Harrison and Hancock counties (Mississippi) in April and May 2008 and data were collected on a number of mental health outcomes. The results of the calculation of Oridinary Least Squares (OLS) regression models revealed that females, African Americans, and less-educated residents manifested the most severe mental health impacts. Most important, consistent findings for depression and Katrina-related psychological stress indicate that residents who were separated from family members, had maximum residential damage, and suffered severe financial problems remained significantly impacted 32 months after Katrina’s landfall. A secondary stressor, in the form of having applications to the Mississippi State Grant Program denied or not processed also predicted personal depression. The implications of these findings are discussed. PMID:20827859

  2. Forest impact estimated with NOAA AVHRR and landsat TM data related to an empirical hurricane wind-field distribution

    USGS Publications Warehouse

    Ramsey, Elijah W.; Hodgson, M.E.; Sapkota, S.K.; Nelson, G.A.

    2001-01-01

    An empirical model was used to relate forest type and hurricane-impact distribution with wind speed and duration to explain the variation of hurricane damage among forest types along the Atchafalaya River basin of coastal Louisiana. Forest-type distribution was derived from Landsat Thematic Mapper image data, hurricane-impact distribution from a suite of transformed advanced very high resolution radiometer images, and wind speed and duration from a wind-field model. The empirical model explained 73%, 84%, and 87% of the impact variances for open, hardwood, and cypress-tupelo forests, respectively. These results showed that the estimated impact for each forest type was highly related to the duration and speed of extreme winds associated with Hurricane Andrew in 1992. The wind-field model projected that the highest wind speeds were in the southern basin, dominated by cypress-tupelo and open forests, while lower wind speeds were in the northern basin, dominated by hardwood forests. This evidence could explain why, on average, the impact to cypress-tupelos was more severe than to hardwoods, even though cypress-tupelos are less susceptible to wind damage. Further, examination of the relative importance of wind speed in explaining the impact severity to each forest type showed that the impact to hardwood forests was mainly related to tropical-depression to tropical-storm force wind speeds. Impacts to cypress-tupelo and open forests (a mixture of willows and cypress-tupelo) were broadly related to tropical-storm force wind speeds and by wind speeds near and somewhat in excess of hurricane force. Decoupling the importance of duration from speed in explaining the impact severity to the forests could not be fully realized. Most evidence, however, hinted that impact severity was positively related to higher durations at critical wind speeds. Wind-speed intervals, which were important in explaining the impact severity on hardwoods, showed that higher durations, but not the

  3. Electromagnetic design analysis and performance improvement of axial field permanent magnet generator for small wind turbine

    NASA Astrophysics Data System (ADS)

    Jung, Tae-Uk

    2012-04-01

    Axial field permanent magnet (AFPM) generators are widely applied for the small wind turbine. The output power of conventional AFPM generator, AFER-NS (Axial Field External Rotor-Non Slotted) generator, is limited by the large reluctance by the long air-gap flux paths. In this paper, the novel structure of AFPM generator, AFIR-S (Axial Field Inner Rotor-Slotted) generator, is suggested to improve the output characteristics. The electromagnetic design analysis and the design improvement of the suggested AFIR-S generator are studied. Firstly, the electromagnetic design analysis was done to increase the power density. Secondly, the design optimizations of the rotor pole-arc ratio and skew angle to increase the output power and to reduce the cogging torque. Finally, the output performances of AFER-NS and AFIR-S generator are compared with each other.

  4. Magnetic field of jupiter and its interaction with the solar wind.

    PubMed

    Smith, E J; Davis, L; Jones, D E; Colburn, D S; Coleman, P J; Dyal, P; Sonett, C P

    1974-01-25

    Jupiter's magnetic field and its interaction with the magnetized solar wind were observed with the Pioneer 10 vector helium magnetometer. The magnetic dipole is directed opposite to that of the earth with a moment of 4.0 gauss R(J)(3) (R(J), Jupiter radius), and an inclination of 15 degrees lying in a system III meridian of 230 degrees . The dipole is offset about 0.1 R(J) north of the equatorial plane and about 0.2 R(J) toward longitude 170 degrees . There is severe stretching of the planetary field parallel to the equator throughout the outer magnetosphere, accompanied by a systematic departure from meridian planes. The field configuration implies substantial plasma effects inside the magnetosphere, such as thermal pressure, centrifugal forces, and differential rotation. As at the earth, the outer boundary is thin, nor diffuse, and there is a detached bow shock. PMID:17821088

  5. Magnetic Field and Wind of Kappa Ceti: Toward the Planetary Habitability of the Young Sun When Life Arose on Earth

    NASA Astrophysics Data System (ADS)

    do Nascimento, J.-D., Jr.; Vidotto, A. A.; Petit, P.; Folsom, C.; Castro, M.; Marsden, S. C.; Morin, J.; Porto de Mello, G. F.; Meibom, S.; Jeffers, S. V.; Guinan, E.; Ribas, I.

    2016-03-01

    We report magnetic field measurements for κ1 Cet, a proxy of the young Sun when life arose on Earth. We carry out an analysis of the magnetic properties determined from spectropolarimetric observations and reconstruct the large-scale surface magnetic field to derive the magnetic environment, stellar winds, and particle flux permeating the interplanetary medium around {κ }1 Cet. Our results show a closer magnetosphere and mass-loss rate of \\dot{M}=9.7× {10}-13 {M}⊙ \\quad {{{yr}}}-1, i.e., a factor of 50 times larger than the current solar wind mass-loss rate, resulting in a larger interaction via space weather disturbances between the stellar wind and a hypothetical young-Earth analogue, potentially affecting the planet’s habitability. Interaction of the wind from the young Sun with the planetary ancient magnetic field may have affected the young Earth and its life conditions.

  6. Solar wind interaction with the Martian upper atmosphere: Crustal field orientation, solar cycle, and seasonal variations

    NASA Astrophysics Data System (ADS)

    Dong, Chuanfei; Bougher, Stephen W.; Ma, Yingjuan; Toth, Gabor; Lee, Yuni; Nagy, Andrew F.; Tenishev, Valeriy; Pawlowski, Dave J.; Combi, Michael R.; Najib, Dalal

    2015-09-01

    A comprehensive study of the solar wind interaction with the Martian upper atmosphere is presented. Three global models: the 3-D Mars multifluid Block Adaptive Tree Solar-wind Roe Upwind Scheme MHD code (MF-MHD), the 3-D Mars Global Ionosphere Thermosphere Model (M-GITM), and the Mars exosphere Monte Carlo model Adaptive Mesh Particle Simulator (M-AMPS) were used in this study. These models are one-way coupled; i.e., the MF-MHD model uses the 3-D neutral inputs from M-GITM and the 3-D hot oxygen corona distribution from M-AMPS. By adopting this one-way coupling approach, the Martian upper atmosphere ion escape rates are investigated in detail with the combined variations of crustal field orientation, solar cycle, and Martian seasonal conditions. The calculated ion escape rates are compared with Mars Express observational data and show reasonable agreement. The variations in solar cycles and seasons can affect the ion loss by a factor of ˜3.3 and ˜1.3, respectively. The crustal magnetic field has a shielding effect to protect Mars from solar wind interaction, and this effect is the strongest for perihelion conditions, with the crustal field facing the Sun. Furthermore, the fraction of cold escaping heavy ionospheric molecular ions [(O2+ and/or O2+)/Total] are inversely proportional to the fraction of the escaping (ionospheric and corona) atomic ion [O+/Total], whereas O2+ and O2+ ion escape fractions show a positive linear correlation since both ion species are ionospheric ions that follow the same escaping path.

  7. Attempts to Simulate Anisotropies of Solar Wind Fluctuations Using MHD with a Turning Magnetic Field

    NASA Technical Reports Server (NTRS)

    Ghosh, Sanjoy; Roberts, D. Aaron

    2010-01-01

    We examine a "two-component" model of the solar wind to see if any of the observed anisotropies of the fields can be explained in light of the need for various quantities, such as the magnetic minimum variance direction, to turn along with the Parker spiral. Previous results used a 3-D MHD spectral code to show that neither Q2D nor slab-wave components will turn their wave vectors in a turning Parker-like field, and that nonlinear interactions between the components are required to reproduce observations. In these new simulations we use higher resolution in both decaying and driven cases, and with and without a turning background field, to see what, if any, conditions lead to variance anisotropies similar to observations. We focus especially on the middle spectral range, and not the energy-containing scales, of the simulation for comparison with the solar wind. Preliminary results have shown that it is very difficult to produce the required variances with a turbulent cascade.

  8. STRONG SOLAR WIND DYNAMIC PRESSURE PULSES: INTERPLANETARY SOURCES AND THEIR IMPACTS ON GEOSYNCHRONOUS MAGNETIC FIELDS

    SciTech Connect

    Zuo, Pingbing; Feng, Xueshang; Wang, Yi; Xie, Yanqiong; Xu, Xiaojun E-mail: fengx@spaceweather.ac.cn

    2015-10-20

    In this investigation, we first present a statistical result of the interplanetary sources of very strong solar wind dynamic pressure pulses (DPPs) detected by WIND during solar cycle 23. It is found that the vast majority of strong DPPs reside within solar wind disturbances. Although the variabilities of geosynchronous magnetic fields (GMFs) due to the impact of positive DPPs have been well established, there appears to be no systematic investigations on the response of GMFs to negative DPPs. Here, we study both the decompression effects of very strong negative DPPs and the compression from strong positive DPPs on GMFs at different magnetic local time sectors. In response to the decompression of strong negative DPPs, GMFs on the dayside near dawn and near dusk on the nightside, are generally depressed. But near the midnight region, the responses of GMF are very diverse, being either positive or negative. For part of the events when GOES is located at the midnight sector, the GMF is found to abnormally increase as the result of magnetospheric decompression caused by negative DPPs. It is known that under certain conditions magnetic depression of nightside GMFs can be caused by the impact of positive DPPs. Here, we find that a stronger pressure enhancement may have a higher probability of producing the exceptional depression of GMF at the midnight region. Statistically, both the decompression effect of strong negative DPPs and the compression effect of strong positive DPPs depend on the magnetic local time, which are stronger at the noon sector.

  9. Strong Solar Wind Dynamic Pressure Pulses: Interplanetary Sources and Their Impacts on Geosynchronous Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Zuo, Pingbing; Feng, Xueshang; Xie, Yanqiong; Wang, Yi; Xu, Xiaojun

    2015-10-01

    In this investigation, we first present a statistical result of the interplanetary sources of very strong solar wind dynamic pressure pulses (DPPs) detected by WIND during solar cycle 23. It is found that the vast majority of strong DPPs reside within solar wind disturbances. Although the variabilities of geosynchronous magnetic fields (GMFs) due to the impact of positive DPPs have been well established, there appears to be no systematic investigations on the response of GMFs to negative DPPs. Here, we study both the decompression effects of very strong negative DPPs and the compression from strong positive DPPs on GMFs at different magnetic local time sectors. In response to the decompression of strong negative DPPs, GMFs on the dayside near dawn and near dusk on the nightside, are generally depressed. But near the midnight region, the responses of GMF are very diverse, being either positive or negative. For part of the events when GOES is located at the midnight sector, the GMF is found to abnormally increase as the result of magnetospheric decompression caused by negative DPPs. It is known that under certain conditions magnetic depression of nightside GMFs can be caused by the impact of positive DPPs. Here, we find that a stronger pressure enhancement may have a higher probability of producing the exceptional depression of GMF at the midnight region. Statistically, both the decompression effect of strong negative DPPs and the compression effect of strong positive DPPs depend on the magnetic local time, which are stronger at the noon sector.

  10. Triple Doppler wind lidar observations during the mountain terrain atmospheric modeling and observations field campaign

    NASA Astrophysics Data System (ADS)

    Wang, Yansen; Hocut, Christopher M.; Hoch, Sebastian W.; Creegan, Edward; Fernando, Harindra J. S.; Whiteman, C. David; Felton, Melvin; Huynh, Giap

    2016-04-01

    Coordinated triple Doppler wind lidars (DWLs) were employed during the Mountain Terrain Atmospheric Modeling and Observations (MATERHORN) program field campaign to observe turbulent winds in the mountain terrain atmospheric boundary layer (ABL). The feasibility of observing large turbulent eddies was investigated by pointing three DWL at an intersecting probe volume adjoining a sonic anemometer mounted on the top of a meteorological tower. The time series and spectra of the sonic anemometer measurement were compared with the lidars. The lidar radial velocities closely followed those of the sonic anemometer, both in time and in the low frequency spectral domain, suggesting that the DWL technique is suitable for observing large turbulent eddies in the ABL. In addition, coordinated scanning triple DWL were used to directly measure the three-dimensional wind vectors, thus circumventing the assumptions required in using single or dual lidar deployments for full velocity measurements. The scanning triple lidar results were in satisfactory agreement with data from tower-based sonic anemometers. Notwithstanding, because of the difficulty of obtaining temporal and spatial synchronizations of the three lidars, the data were scant since a large amount of data had to be rejected in postprocessing. This difficulty is surmountable in the future by employing a robust control system for coordinated scanning.

  11. Ulysses Composition, Plasma and Magnetic Field Observations of High Speed Solar wind Streams

    NASA Technical Reports Server (NTRS)

    Smith, E. J.

    1997-01-01

    During 1992-3 as the Ulysses spacecraft passed in and out of the southern high speed solar wind stream, the Solar Wind Ion Spectrometer, SWICS made continuous composition and temperature measurements of all major solar wind ions.

  12. Dehydration processes in the Indian monsoon anticyclone : Lagrangian analysis and sensitivity to vertical wind fields.

    NASA Astrophysics Data System (ADS)

    James, R.; Bonazzola, M.; Legras, B.; Surbled, K.; Fueglistaler, S.

    2007-12-01

    During Asian monsoon season, the large-scale monsoon flux generates a persistent anticyclonic circulation at the tropopause over the sub-tropical part of Asia (15°N to 40°N). The anticyclonic region is associated with a large water vapor maxima, which can hardly be explained by the seasonal variation of tropopause temperatures alone. In the upper troposphere, the moistening effect of deep convective events in the anticyclone has been pointed out by Randel and Park (JGR, 10.1029/2005JD006490, 2006). However, at higher levels the deep convective area is separated from the anticyclonic region (Park et al., JGR, 10.1029/2006JD008294, 2007). The large-scale circulation (slow ascent and anticyclonic barrier) seems hence essential to explain the water vapor distribution observed at 100 hPa (MLS/AURA or MIPAS). In this context, the ability of the large-scale wind fields to represent the water vapor distribution has been studied from back-trajectories. The calculations have been performed over three summers (1998, 1999 and 2000) using two representations of the vertical wind in the ERA-40 dataset and the new ERA-Interim: the "classical" wind (from divergence equation) and the diabatic wind (from temperature tendency equation). Coupled to a simple microphysical model, back-trajectories can reconstruct water vapor maps (Fueglistaler et al., JGR, 10.1029/2004JD005516, 2005). Here, the comparison to MLS/AURA retrievements at 100 hPa shows that : if "classical" wind calculations exhibit large discrepancies, diabatic winds accurately reconstruct the location and the concentration of the indian monsoon water vapor maxima without represented small-scale micro-physic. Investigating transport and dehydration processes along trajectories (intersection with isentrops, clouds from CLAUS,...) the Lagrangian approach offers a synthetic scenario. After being quickly lifted by deep convection over the Bay of Bengal until 350-360 K, most of the parcels are freezed-dry around 370 K above

  13. Modeling the wind-fields of accidental releases by mesoscale forecasting

    SciTech Connect

    Albritton, J.R.; Lee, R.L.; Mobley, R.L.; Pace, J.C.; Hodur, R.A.; Lion, C.S.

    1997-07-01

    Modeling atmospheric releases even during fair weather can present a sever challenge to diagnostic, observed-data-driven, models. Such schemes are often handicapped by sparse input data from meteorological surface stations and soundings. Forecasting by persistence is only acceptable for a few hours and cannot predict important changes in the diurnal cycle or from synoptic evolution. Many accident scenarios are data-sparse in space and/or time. Here we describe the potential value of limited-area, mesoscale, forecast models for real-time emergency response. Simulated wind-fields will be passed to ARAC`s operational models to produce improved forecasts of dispersion following accidents.

  14. Interplanetary magnetic field effects on the interaction of the solar wind with Venus

    NASA Astrophysics Data System (ADS)

    Phillips, John Lynch

    The solar wind interaction with Venus is examined with emphasis on the role of the interplanetary magnetic field (IMF) using observations from Pioneer Venus Orbiter (PVO). Based on a survey of low altitude magnetometer observations, the planetary magnetic moment is less than 8.4 times 10 to the 10th power Tm (3), or roughly 1/100,000 of the terrestrial moment. As a result, the impact of changing IMF orientation on the interaction is very different at Venus than at the magnetized planets. The solar plasma interacts directly with the ionospheric plasma, which generally is able to maintain a shielding current system which constitutes an impenetrable boundary.

  15. An Adjoint-based Method for the Inversion of the Juno and Cassini Gravity Measurements into Wind Fields

    NASA Astrophysics Data System (ADS)

    Galanti, Eli; Kaspi, Yohai

    2016-04-01

    During 2016-17, the Juno and Cassini spacecraft will both perform close eccentric orbits of Jupiter and Saturn, respectively, obtaining high-precision gravity measurements for these planets. These data will be used to estimate the depth of the observed surface flows on these planets. All models to date, relating the winds to the gravity field, have been in the forward direction, thus only allowing the calculation of the gravity field from given wind models. However, there is a need to do the inverse problem since the new observations will be of the gravity field. Here, an inverse dynamical model is developed to relate the expected measurable gravity field, to perturbations of the density and wind fields, and therefore to the observed cloud-level winds. In order to invert the gravity field into the 3D circulation, an adjoint model is constructed for the dynamical model, thus allowing backward integration. This tool is used for the examination of various scenarios, simulating cases in which the depth of the wind depends on latitude. We show that it is possible to use the gravity measurements to derive the depth of the winds, both on Jupiter and Saturn, also taking into account measurement errors. Calculating the solution uncertainties, we show that the wind depth can be determined more precisely in the low-to-mid-latitudes. In addition, the gravitational moments are found to be particularly sensitive to flows at the equatorial intermediate depths. Therefore, we expect that if deep winds exist on these planets they will have a measurable signature by Juno and Cassini.

  16. Magnetic Fields in the Lunar Wake and Its Responses to the External Solar Wind Conditions

    NASA Astrophysics Data System (ADS)

    Wong, H.; Ma, Y.; Ip, W.; Xu, X.

    2013-12-01

    The Moon has no thick atmosphere and no global magnetic field. When the solar wind plasma impacts with the Moon, particles can be mostly absorbed by the lunar surface, so it leaves a plasma void downstream, i.e., the lunar wake. Considering the pressure balance, people could expect that the magnetic field may have an enhancement in the central lunar wake. Such an enhancement has been detected earlier [Ogilvie et al., 1996; Owen et al., 1996; Halekas et al., 2005]. Besides the observational analysis, lots of theoretical studies and numerical modeling have also been used to investigate this process, e.g., in MHD [Xie et al., 2012], 3D hybrid model [Wiehle et al., 2011; Wang et al., 2011; Holmström et al., 2012] as well as PIC model [Birch and Chapman, 2011]. In the present study, we find that the enhancement of magnetic field in the central part is larger in the deep lunar wake than that in the far downtail region with the observations from the two ARTEMIS probes. However, in the wake boundary, there are usually two depletion dips on the two sides. As the distances from the lunar center increase, the slope of the enhancement of magnetic field strength becomes smoother. It means that the enhancement of magnitude in the deep lunar wake is sharpest from the boundary to the center. Another signature observed is that the magnitude of magnetic field decreases in the wake center as the distance from the body increases. So the distributions of magnetic field strength across the cross section as a function of distances from the lunar center are different. We have also tried to find the responses of the magnetic field distributions in the lunar wake to the angle of the IMF with respect to the direction of the solar wind flow. In the near wake, the dependence of field distributions on the angle is not obvious in the observational data. However, in the far downstream region from the lunar body, as the angle decreases, the amplitude of the magnetic field fluctuations becomes

  17. Experimental study of the effects of alternating fields on HTS coils according to the winding insulation conditions

    NASA Astrophysics Data System (ADS)

    Hwang, Y. J.; Ahn, M. C.; Lee, T. S.; Lee, W. S.; Ko, T. K.

    2013-08-01

    This paper examines the effects of alternating fields on high-temperature superconducting (HTS) coils according to the winding insulation condition. Alternating fields can occur in synchronous machines (armature reaction, faults) and other devices. In superconducting synchronous machines, alternating fields affect the operational characteristics of the machine and the superconducting field coil. Therefore, a method of reducing the effects of alternating fields is necessary in superconducting synchronous design. In this study, the effects of alternating fields on the HTS field coil according to the winding insulation condition were experimentally evaluated. The experimental results show that HTS coils made using the no-insulation technique can be a solution for reducing the effects of the alternating field. These results are expected to suggest useful data for applications of HTS field coils in superconducting synchronous machines.

  18. Basin-Scale Wind Transport during the MILAGRO Field Campaign and Comparison to Climatology Using Cluster Analysis

    SciTech Connect

    de Foy, B.; Fast, Jerome D.; Paech, S. J.; Phillips, D.; Walters, J. T.; Coulter, Richard L.; Martin, Tim J.; Pekour, Mikhail S.; Shaw, William J.; Kastendeuch, P. P.; Marley, Nancy A.; Retama, A.; Molina, Luisa T.

    2008-03-03

    The MILAGRO field campaign was a multi-agency international collaborative project to evaluate the regional impacts of the Mexico City air pollution plume as a means of understanding urban impacts on the global climate. Mexico City lies on an elevated plateau with mountains on three sides and has complex mountain and surface-driven wind flows. This paper asks what the wind transport was in the basin during the field campaign and how representative it was of the climatology. Surface meteorology and air quality data, radiosoundings and radar wind profiler data were collected at sites in the basin and its vicinity. Cluster analysis is used to identify the dominant wind patterns both during the campaign and within the past 10 years of operational data from the warm dry season. Our analysis shows that March 2006 was representative of typical flow patterns experienced in the basin. Six episode types were identified for the basin scale circulation providing a way of interpreting atmospheric chemistry and particulate data collected during the campaign. Decoupling between surface winds and those aloft had a strong influence in leading to convection and poor air quality episodes. Hourly characterisation of wind circulation during the MILAGRO, MCMA-2003 and IMADA field campaigns will enable the comparisons of similar air pollution episodes and the evaluation of the impact of wind transport on measurements of the atmospheric chemistry taking place in the basin.

  19. Field and Wind Tunnel Comparison of Four Aerosol Samplers Using Agricultural Dusts

    PubMed Central

    Reynolds, Stephen J.; Nakatsu, Jason; Tillery, Marvin; Keefe, Thomas; Mehaffy, John; Thorne, Peter S.; Donham, Kelley; Nonnenmann, Matthew; Golla, Vijay; O'shaughnessy, Patrick

    2009-01-01

    Occupational lung disease is a significant problem among agricultural workers exposed to organic dusts. Measurements of exposure in agricultural environments in the USA have traditionally been conducted using 37-mm closed-face cassettes (CFCs) and respirable Cyclones. Inhalable aerosol samplers offer significant improvement for dose estimation studies to reduce respiratory disease. The goals of this study were to determine correction factors between the inhalable samplers (IOM and Button) and the CFC and Cyclone for dusts sampled in livestock buildings and to determine whether these factors vary among livestock types. Determination of these correction factors will allow comparison between inhalable measurements and historical measurements. Ten sets of samples were collected in swine, chicken, turkey, and dairy facilities in both Colorado and Iowa. Pairs of each sampling device were attached to the front and back of a rotating mannequin. Laboratory studies using a still-air chamber and a wind tunnel provided information regarding the effect of wind speed on sampler performance. Overall, the IOM had the lowest coefficient of variation (best precision) and was least affected by changes in wind speed. The performance of the Button was negatively impacted in poultry environments where larger (feather) particulates clogged the holes in the initial screen. The CFC/IOM ratios are important for comparisons between newer and older studies. Wind speed and dust type were both important factors affecting ratios. Based on the field studies (Table 6), a ratio of 0.56 is suggested as a conversion factor for the CFC/IOM (average for all environments because of no statistical difference). Suggested conversion factors for the Button/IOM are swine (0.57), chicken (0.80), turkey (0.53), and dairy (0.67). Any attempt to apply a conversion factor between the Cyclone and inhalable samplers is not recommended. PMID:19443852

  20. Investigation of the turbulent wind field below 500 feet altitude at the Eastern Test Range, Florida

    NASA Technical Reports Server (NTRS)

    Blackadar, A. K.; Panofsky, H. A.; Fiedler, F.

    1974-01-01

    A detailed analysis of wind profiles and turbulence at the 150 m Cape Kennedy Meteorological Tower is presented. Various methods are explored for the estimation of wind profiles, wind variances, high-frequency spectra, and coherences between various levels, given roughness length and either low-level wind and temperature data, or geostrophic wind and insolation. The relationship between planetary Richardson number, insolation, and geostrophic wind is explored empirically. Techniques were devised which resulted in surface stresses reasonably well correlated with the surface stresses obtained from low-level data. Finally, practical methods are suggested for the estimation of wind profiles and wind statistics.

  1. Effect of a magnetic field on massive-star winds - I. Mass-loss and velocity for a dipole field

    NASA Astrophysics Data System (ADS)

    Bard, Christopher; Townsend, Richard H. D.

    2016-11-01

    We generalize the Rigid-Field Hydrodynamic equations to accommodate arbitrary magnetic field topologies, resulting in a new Arbitrary Rigid-Field Hydrodynamic (ARFHD) formalism. We undertake a critical point calculation of the steady-state ARFHD equations with a CAK-type radiative acceleration and determine the effects of a dipole magnetic field on the usual CAK mass-loss rate and velocity structure. Enforcing the proper optically thin limit for the radiative line-acceleration is found to decrease both the mass-loss and wind acceleration, while rotation boosts both properties. We define optically thin correction and rotation parameters to quantify these effects on the global mass-loss rate and develop scaling laws for the surface mass-flux as a function of surface colatitude. These scaling laws are found to agree with previous laws derived from magnetohydrodynamic simulations of magnetospheres. The dipole magnetosphere velocity structure is found to differ from a global beta-velocity law, which contradicts a central assumption of the previously developed XADM model of X-ray emission from magnetospheres.

  2. Eyes in the sky. Interactions between asymptotic giant branch star winds and the interstellar magnetic field

    NASA Astrophysics Data System (ADS)

    van Marle, A. J.; Cox, N. L. J.; Decin, L.

    2014-10-01

    Context. The extended circumstellar envelopes (CSEs) of evolved low-mass stars display a large variety of morphologies. Understanding the various mechanisms that give rise to these extended structures is important to trace their mass-loss history. Aims: Here, we aim to examine the role of the interstellar magnetic field in shaping the extended morphologies of slow dusty winds of asymptotic giant branch (AGB) stars in an effort to pin-point the origin of so-called eye shaped CSEs of three carbon-rich AGB stars. In addition, we seek to understand if this pre-planetary nebula (PN) shaping can be responsible for asymmetries observed in PNe. Methods: Hydrodynamical simulations are used to study the effect of typical interstellar magnetic fields on the free-expanding spherical stellar winds as they sweep up the local interstellar medium (ISM). Results: The simulations show that typical Galactic interstellar magnetic fields of 5 to 10 μG are sufficient to alter the spherical expanding shells of AGB stars to appear as the characteristic eye shape revealed by far-infrared observations. The typical sizes of the simulated eyes are in accordance with the observed physical sizes. However, the eye shapes are transient in nature. Depending on the stellar and interstellar conditions, they develop after 20 000 to 200 000 yrs and last for about 50 000 to 500 000 yrs, assuming that the star is at rest relative to the local interstellar medium. Once formed, the eye shape develops lateral outflows parallel to the magnetic field. The explosion of a PN in the centre of the eye-shaped dust shell gives rise to an asymmetrical nebula with prominent inward pointing Rayleigh-Taylor instabilities. Conclusions: Interstellar magnetic fields can clearly affect the shaping of wind-ISM interaction shells. The occurrence of the eyes is most strongly influenced by stellar space motion and ISM density. Observability of this transient phase is favoured for lines-of-sight perpendicular to the

  3. Study of the solar wind coupling to the time difference horizontal geomagnetic field

    NASA Astrophysics Data System (ADS)

    Wintoft, P.

    2005-07-01

    The local ground geomagnetic field fluctuations (Δ B) are dominated by high frequencies and 83% of the power is located at periods of 32 min or less. By forming 10-min root-mean-square (RMS) of Δ B a major part of this variation is captured. Using measured geomagnetic induced currents (GIC), from a power grid transformer in Southern Sweden, it is shown that the 10-min standard deviation GIC may be computed from a linear model using the RMS Δ X and Δ Y at Brorfelde (BFE: 11.67° E, 55.63° N), Denmark, and Uppsala (UPS: 17.35° E, 59.90° N), Sweden, with a correlation of 0.926±0.015. From recurrent neural network models, that are driven by solar wind data, it is shown that the log RMS Δ X and Δ Y at the two locations may be predicted up to 30 min in advance with a correlation close to 0.8: 0.78±0.02 for both directions at BFE; 0.81±0.02 and 0.80±0.02 in the X- and Y-directions, respectively, at UPS. The most important inputs to the models are the 10-min averages of the solar wind magnetic field component Bz and velocity V, and the 10-min standard deviation of the proton number density σn. The average proton number density n has no influence. Keywords. Magnetospheric physics (Solar wind - magnetosphere interactions) Geomagnetism and paleomagnetism (Rapid time variations)

  4. The electric wind of Venus: A global and persistent "polar wind"-like ambipolar electric field sufficient for the direct escape of heavy ionospheric ions

    NASA Astrophysics Data System (ADS)

    Collinson, Glyn A.; Frahm, Rudy A.; Glocer, Alex; Coates, Andrew J.; Grebowsky, Joseph M.; Barabash, Stas; Domagal-Goldman, Shawn D.; Fedorov, Andrei; Futaana, Yoshifumi; Gilbert, Lin K.; Khazanov, George; Nordheim, Tom A.; Mitchell, David; Moore, Thomas E.; Peterson, William K.; Winningham, John D.; Zhang, Tielong L.

    2016-06-01

    Understanding what processes govern atmospheric escape and the loss of planetary water is of paramount importance for understanding how life in the universe can exist. One mechanism thought to be important at all planets is an "ambipolar" electric field that helps ions overcome gravity. We report the discovery and first quantitative extraterrestrial measurements of such a field at the planet Venus. Unexpectedly, despite comparable gravity, we show the field to be five times stronger than in Earth's similar ionosphere. Contrary to our understanding, Venus would still lose heavy ions (including oxygen and all water-group species) to space, even if there were no stripping by the solar wind. We therefore find that it is possible for planets to lose heavy ions to space entirely through electric forces in their ionospheres and such an "electric wind" must be considered when studying the evolution and potential habitability of any planet in any star system.

  5. Uncertainty contribution of a wind turbine to the electric field of a DVOR antenna as a function of wind direction and rotor position

    NASA Astrophysics Data System (ADS)

    Sandmann, Sergei; Garbe, Heyno

    2016-09-01

    The presence of a wind turbine (WT) has the potential to distort electromagnetic fields emitted by terrestrial radio navigation aids. In this paper especially the field distortion of a Doppler Very High Frequency Omnidirectional Radio Range (DVOR) surveillance navigation system is investigated as a function of wind direction and rotor position. Therefor, the field distribution of a DVOR is simulated in the surrounding of a WT for 104 combinations of the angles of wind direction and rotor position. Furthermore, these calculations are executed for two different rotor diameters and 10 steps of distance between DVOR and WT in the range of 10 km. Based on the calculated data a method to estimate the maximum field distortion is developed. It is shown that the presented method allows to approximate the worst case field distortion with the results of two general simulation setups. Eliminating the need of simulating all possible geometric constellations of the WT this method hereby offers the benefit of significantly reduced simulation effort.

  6. Interplanetary Field Enhancements: The Interaction between Solar Wind and Interplanetary Dusty Plasma Released by Interplanetary Collisions

    NASA Astrophysics Data System (ADS)

    Lai, Hairong

    Interplanetary field enhancements (IFEs) are unique large-scale structures in the solar wind. During IFEs, the magnetic-field strength is significantly enhanced with little perturbation in the solar-wind plasma. Early studies showed that IFEs move at nearly the solar-wind speed and some IFEs detected at 0.72AU by Pioneer Venus Orbiter (PVO) are associated with material co-orbiting with asteroid Oljato. To explain the observed IFE features, we develop and test an IFE formation hypothesis: IFEs result from interactions between the solar wind and clouds of nanoscale charged dust particles released in interplanetary collisions. This hypothesis predicts that the magnetic field drapes and the solar wind slows down in the upstream. Meanwhile the observed IFE occurrence rate should be comparable with the detectable interplanetary collision rate. Based on this hypothesis, we can use the IFE occurrence to determine the spatial distribution and temporal variation of interplanetary objects which produce IFEs. To test the hypothesis, we perform a systematic survey of IFEs in the magnetic-field data from many spacecraft. Our datasets cover from 1970s to present and from inner than 0.3AU to outer than 5 AU. In total, more than 470 IFEs are identified and their occurrences show clustering features in both space and time. We use multi-spacecraft simultaneous observations to reconstruct the magnetic-field geometry and find that the magnetic field drapes in the upstream region. The results of a superposed epoch study show that the solar wind slows down in the upstream and there is a plasma depletion region near the IFE centers. In addition, the solar-wind slowdown and plasma depletion feature are more significant in larger IFEs. The mass contained in IFEs can be estimated by balancing the solar-wind pressure force exerted on the IFEs against the solar gravity. The solar-wind slowdown resultant from the estimated mass is consistent with the result in superposed epoch study. The

  7. Solar wind driven empirical forecast models of the time derivative of the ground magnetic field

    NASA Astrophysics Data System (ADS)

    Wintoft, Peter; Wik, Magnus; Viljanen, Ari

    2015-03-01

    Empirical models are developed to provide 10-30-min forecasts of the magnitude of the time derivative of local horizontal ground geomagnetic field (|dBh/dt|) over Europe. The models are driven by ACE solar wind data. A major part of the work has been devoted to the search and selection of datasets to support the model development. To simplify the problem, but at the same time capture sudden changes, 30-min maximum values of |dBh/dt| are forecast with a cadence of 1 min. Models are tested both with and without the use of ACE SWEPAM plasma data. It is shown that the models generally capture sudden increases in |dBh/dt| that are associated with sudden impulses (SI). The SI is the dominant disturbance source for geomagnetic latitudes below 50° N and with minor contribution from substorms. However, at occasions, large disturbances can be seen associated with geomagnetic pulsations. For higher latitudes longer lasting disturbances, associated with substorms, are generally also captured. It is also shown that the models using only solar wind magnetic field as input perform in most cases equally well as models with plasma data. The models have been verified using different approaches including the extremal dependence index which is suitable for rare events.

  8. Field Test Results from a 10 kW Wind Turbine with Active Flow Control

    NASA Astrophysics Data System (ADS)

    Rice, Thomas; Bychkova, Veronika; Taylor, Keith; Clingman, Dan; Amitay, Michael

    2015-11-01

    Active flow control devices including synthetic jets and dynamic vortex generators were tested on a 10 kW wind turbine at RPI. Previous work has shown that load oscillations caused by dynamic stall could be modified through the use of active flow control by injecting momentum into the flow field near the leading edge of a dynamically pitching model. In this study, this work has been extended to its logical conclusion, field-testing active flow control on a real wind turbine. The blades in the current study have a 0.28m chord and 3.05m span, no twist or taper, and were retrofitted with six synthetic jets on one blade and ten dynamic vortex generators on a second blade. The third blade of this turbine was not modified, in order to serve as a control. Strain gauges were installed on each blade to measure blades' deflection. A simple closed loop control was demonstrated and preliminary results indicate reduced vibrational amplitude. Future testing will be conducted on a larger scale, 600kW machine at NREL, incorporating information collected during this study.

  9. Calm before the spawn: global coral spawning patterns are explained by regional wind fields.

    PubMed

    van Woesik, R

    2010-03-01

    Most corals in tropical localities broadcast their gametes into the water column, yet we have a poor understanding of what forces reproductive schedules. Moreover, recent studies show considerable geographical variation in the duration of the coral spawning season. For example, on the Great Barrier Reef, corals display tight coupling, while corals in Kenya spawn over seven months. This study reconciles the regional variance by testing the hypothesis that regional wind fields are the corals' ultimate reproductive proxy. Regions with short calm periods should be more tightly coupled than regions with calm periods extending for several months. Regional wind fields were assessed at seven localities, between 1997 and 2006, using the 11 GHz channel radiometer tropical microwave imager (TMI) onboard the tropical rainfall measuring mission (TRMM). There was a direct positive relationship between the duration of regional calm periods and the coupling of mass coral spawning. Ultimate long-term evolutionary advantages of releasing gametes during calm periods ensure fertilization and facilitate larval retention and local recruitment. Coupling mass spawning with seasonally calm periods agrees strongly with recent genetic evidence of local dispersal and high local retention.

  10. Geochemical and magnetic characteristics of aeolian transported materials under different near-surface wind fields: An experimental study

    NASA Astrophysics Data System (ADS)

    Wang, Xunming; Lang, Lili; Hua, Ting; Zhang, Caixia; Xia, Dunsheng

    2015-06-01

    By combining field investigations, field sampling, wind-tunnel experiments, and laboratory measurements, the relationships between near-surface winds and the geochemical and magnetic characteristics of wind-transported materials were statistically analyzed. Our study was conducted using bulk surface samples from a major potential dust source area in Central Asia (the Ala Shan Plateau). Under near-surface wind velocities ranging from 8 to 22 m/s, the coefficients of variation ranged between 1.6% and 14.9% for χlf, 1.4% and 11.0% for χARM, and 0.7% and 12.3% for SIRM of the transported materials. For the 26 elements and oxides investigated, the coefficients of variation of Ti, Cr, As, Zr, Ce, Pb, and Cu in the samples were greater than 10%. No consistent patterns were found between magnetic characteristics and elemental and iron oxide concentrations as a function of variations in near-surface wind velocities. In potential dust source areas under near-surface wind velocities, there are variations in the relationships between magnetic and geochemical characteristics in the fine fractions of transported materials with different particle sizes. Given the wide variation in magnetic and geochemical characteristics of aeolian-transported materials under different near-surface winds, their use as proxies for past climate reconstruction must be carefully appraised.

  11. Investigation of Solar Wind Coupling to the High-Latitude Ionospheric Reverse Convection Electric Field during Large Positive IMF Bz

    NASA Astrophysics Data System (ADS)

    Clauer, C. R.; Deshpande, K.; Xu, Z.; Hartinger, M.; Weimer, D. R.; Nicolls, M. J.

    2015-12-01

    An empirical determination of the coupling function between the solar wind dynamo electric field and the high latitude ionospheric electric field is possible using the Weiner filter technique. We investigate the response of the high latitude reverse convection electric field measured by the Resolute Incoherent Scatter Radar (RISR) during periods of large northward IMF for two CME-related events 12-13 September 2014 and 22 - 23 June 2015. The technique provides the most general linear coupling function including frequency response and time delays. We find that the solar wind is strongly coupled to the high latitude reverse convection electric field. We discuss the details of this coupling as it relates to various parameters that may influence the coupling efficiency, such as solar wind mach number, plasma beta, ionospheric Pederson conductivity, etc.

  12. Transient behavior of a flare-associated solar wind. I. Gas dynamics in a radial open field region

    SciTech Connect

    Nagai, F.

    1984-02-01

    A main purpose of this paper is to investigate by numerical calculations how a model solar wind, initially in a steady state and in energy balance, is disturbed and deformed and how it acquires a high speed when heat liberation corresponding to energy release in solar flares of importance approx.1 occurs around the lower corona in a radial open field region. This transient behavior of the flare-associated solar wind is modeled between 1 and 8 solar radii.

  13. Drug markets during the Katrina disaster

    PubMed Central

    Dunlap, Eloise; Golub, Andrew

    2011-01-01

    Purpose The purpose of this paper is to examine the experiences of poor drug users and sellers who remained in New Orleans during Hurricane Katrina in 2005 to identify their special needs and the unique challenges they present to disaster management. Design/methodology/approach Semi-structured, open-ended interviews were conducted with 119 poor, predominantly African-American, drug users and sellers. Their stories in their own words provide a mosaic of drug-related experiences from the period immediately preceding the storm through evacuation and reveal the motivations behind their behaviors. Findings Many drug users placed partying, maintaining their habits, and making money ahead of personal safety and evacuation. Drug use and sales led many not to evacuate before the storm, to use drugs in congregate shelters, to avoid shelters, to roam through flooded debris-strewn streets, to loot stores and homes of drug dealers, and to use violence or the threat of violence to achieve their drug-related aims. Originality/value During a disaster, many poor drug users place risks on themselves, their families, their communities and ultimately on rescue workers. The conclusion presents pragmatic and humanitarian guidelines for successfully addressing this additional challenge. The recommendations are consistent with other suggestions concerning the special needs of indigent populations. PMID:21841898

  14. Controlling disasters: recognising latent goals after Hurricane Katrina.

    PubMed

    Miller, Lee M

    2012-01-01

    Classic sociological theory can be used to interpret the aftermath of Hurricane Katrina, which made landfall in the United States on 29 August 2005. The delayed and ineffective response to the storm and the subsequent failure of the levees become more understandable when one considers the latent goals of social control in disaster recovery. Constructing the survivors as suspect or criminal and conceptualising the impacts of the disaster as individual problems occurred in order to justify the emphasis on controlling the survivors of Katrina rather than on assisting them. Parallels are drawn here between the disaster response featuring social control efforts and a recent paradigmatic shift in criminal justice from justice to 'risk management'. Recognition of the implicit aims of the inadequate disaster response provides a more complete explanation of why post-Katrina efforts failed to achieve the manifest goals of response and recovery. The conclusion suggests ways to ensure more equitable and just disaster responses.

  15. Compact, Engineered 2-Micron Coherent Doppler Wind Lidar Prototype for Field and Airborne Evaluation

    NASA Technical Reports Server (NTRS)

    Kavaya, Michael J.; Amzajerdian, Farzin; Koch, Grady J.

    2006-01-01

    The state-of-the-art 2-micron coherent Doppler wind lidar breadboard at NASA/LaRC will be engineered and compactly packaged consistent with future aircraft flights. The packaged transceiver will be integrated into a coherent Doppler wind lidar system test bed at LaRC. Atmospheric wind measurements will be made to validate the packaged technology. This will greatly advance the coherent part of the hybrid Doppler wind lidar solution to the need for global tropospheric wind measurements.

  16. Influence of hurricane wind field in the structure of directional wave spectra

    NASA Astrophysics Data System (ADS)

    Esquivel-Trava, Bernardo; Ocampo-Torres, Francisco J.; Osuna, Pedro

    2015-04-01

    Extensive field measurements of wind waves in deep waters in the Gulf of Mexico and Caribbean Sea, have been analyzed to describe the spatial structure of directional wave spectra during hurricane conditions. Following Esquivel-Trava et al. (2015) this analysis was made for minor hurricanes (categories 1 and 2) and major hurricanes (categories 3, 4 and 5). In both cases the directionality of the energy wave spectrum is similar in all quadrants. Some differences are observed however, and they are associated with the presence and the shape of swell energy in each quadrant. Three numerical experiments using the spectral wave prediction model SWAN were carried out to gain insight into the mechanism that controls the directional and frequency distributions of hurricane wave energy. The aim of the experiments is to evaluate the effect of the translation speed of the hurricane and the presence of concentric eye walls, on both the wave growth process and the shape of the directional wave spectrum. The HRD wind field of Hurricane Dean on August 20 at 7:30 was propagated at two different velocities (5 and 10 m/s). An idealized concentric eye wall (a Gaussian function that evolve in time along a path in the form of an Archimedean spiral) was imposed to the wind field. The white-capping formulation of Westhuysen et al. (2007) was selected. The wave model represents fairly well the directionality of the energy and the shape of the directional spectra in the hurricane domain. The model results indicate that the forward movement of the storm influences the development of the waves, consistent with field observations. This work has been supported by CONACYT scholarship 164510 and projects RugDisMar (155793), CB-2011-01-168173 and the Department of Physical Oceanography of CICESE. References Esquivel-Trava, B., Ocampo-Torres, F. J., & Osuna, P. (2015). Spatial structure of directional wave spectra in hurricanes. Ocean Dynam., 65(1), 65-76. doi:10.1007/s10236-014-0791-9 Van der

  17. Wind as an abiotic factor of Colorado potato beetle (Coleoptera: Chrysomelidae) flight take-off activity under field conditions.

    PubMed

    Boiteau, G; Mccarthy, P C; MacKinley, P D

    2010-10-01

    The flight take-off activity of Colorado potato beetles, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), was significantly higher at a landscape-protected than at semiexposed and exposed sites in a 2-yr field study. In both years, mean daylight temperature, solar radiation, and relative humidity were generally similar at all sites, but wind speed was lower at the protected site than at the exposed sites. Results suggest that wind was the limiting abiotic factor for flight take-off at the exposed site. Caged beetles exposed to constant wind speeds of 3.4, 4.7, and 7.0 m/s showed a significant corresponding decrease in number of flight take-off. There was no cumulative effect of wind exposure on the readiness of the beetles to fly, suggesting that wind acts as a physical barrier to flight take-off. It should be possible to reduce Colorado potato beetle flight dispersal by selecting fields most exposed to wind over landscape-protected fields when rotating potato, Solanum tuberosum L., crops.

  18. Small wind turbine performance evaluation using field test data and a coupled aero-electro-mechanical model

    NASA Astrophysics Data System (ADS)

    Wallace, Brian D.

    A series of field tests and theoretical analyses were performed on various wind turbine rotor designs at two Penn State residential-scale wind-electric facilities. This work involved the prediction and experimental measurement of the electrical and aerodynamic performance of three wind turbines; a 3 kW rated Whisper 175, 2.4 kW rated Skystream 3.7, and the Penn State designed Carolus wind turbine. Both the Skystream and Whisper 175 wind turbines are OEM blades which were originally installed at the facilities. The Carolus rotor is a carbon-fiber composite 2-bladed machine, designed and assembled at Penn State, with the intent of replacing the Whisper 175 rotor at the off-grid system. Rotor aerodynamic performance is modeled using WT_Perf, a National Renewable Energy Laboratory developed Blade Element Momentum theory based performance prediction code. Steady-state power curves are predicted by coupling experimentally determined electrical characteristics with the aerodynamic performance of the rotor simulated with WT_Perf. A dynamometer test stand is used to establish the electromechanical efficiencies of the wind-electric system generator. Through the coupling of WT_Perf and dynamometer test results, an aero-electro-mechanical analysis procedure is developed and provides accurate predictions of wind system performance. The analysis of three different wind turbines gives a comprehensive assessment of the capability of the field test facilities and the accuracy of aero-electro-mechanical analysis procedures. Results from this study show that the Carolus and Whisper 175 rotors are running at higher tip-speed ratios than are optimum for power production. The aero-electro-mechanical analysis predicted the high operating tip-speed ratios of the rotors and was accurate at predicting output power for the systems. It is shown that the wind turbines operate at high tip-speeds because of a miss-match between the aerodynamic drive torque and the operating torque of the wind

  19. On the Origin of the 1/f Spectrum in the Solar Wind Magnetic Field

    NASA Astrophysics Data System (ADS)

    Verdini, Andrea; Grappin, Roland; Pinto, Rui; Velli, Marco

    2012-05-01

    We present a mechanism for the formation of the low-frequency 1/f magnetic spectrum based on numerical solutions of a shell-reduced MHD model of the turbulent dynamics inside the sub-Alfvénic solar wind. We assign reasonably realistic profiles to the wind speed and the density along the radial direction, and a radial magnetic field. Alfvén waves of short periodicity (600 s) are injected at the base of the chromosphere, penetrate into the corona, and are partially reflected, thus triggering a turbulent cascade. The cascade is strong for the reflected wave while it is weak for the outward propagating waves. Reflection at the transition region recycles the strong turbulent spectrum into the outward weak spectrum, which is advected beyond the Alfvénic critical point without substantial evolution. There, the magnetic field has a perpendicular power-law spectrum with slope close to the Kolmogorov -5/3. The parallel spectrum is inherited from the frequency spectrum of large (perpendicular) eddies. The shape is a double power law with slopes of ~= - 1 and -2 at low and high frequencies, respectively, with the position of the break depending on the injected spectrum. We suggest that the double power-law spectrum measured by Helios at 0.3 AU, where the average magnetic field is not aligned with the radial (contrary to our assumptions), results from the combination of such different spectral slopes. At low frequency the parallel spectrum dominates with its characteristic 1/f shape, while at higher frequencies its steep spectral slope (-2) is masked by the more energetic perpendicular spectrum (slope -5/3).

  20. Saturn's auroral morphology and field-aligned currents during a solar wind compression

    NASA Astrophysics Data System (ADS)

    Badman, S. V.; Provan, G.; Bunce, E. J.; Mitchell, D. G.; Melin, H.; Cowley, S. W. H.; Radioti, A.; Kurth, W. S.; Pryor, W. R.; Nichols, J. D.; Jinks, S. L.; Stallard, T. S.; Brown, R. H.; Baines, K. H.; Dougherty, M. K.

    2016-01-01

    On 21-22 April 2013, during a coordinated auroral observing campaign, instruments onboard Cassini and the Hubble Space Telescope observed Saturn's aurora while Cassini traversed Saturn's high latitude auroral field lines. Signatures of upward and downward field-aligned currents were detected in the nightside magnetosphere in the magnetic field and plasma measurements. The location of the upward current corresponded to the bright ultraviolet auroral arc seen in the auroral images, and the downward current region was located poleward of the upward current in an aurorally dark region. Within the polar cap magnetic field and plasma fluctuations were identified with periods of ∼20 and ∼60 min. The northern and southern auroral ovals were observed to rock in latitude in phase with the respective northern and southern planetary period oscillations. A solar wind compression impacted Saturn's magnetosphere at the start of 22 April 2013, identified by an intensification and extension to lower frequencies of the Saturn kilometric radiation, with the following sequence of effects: (1) intensification of the auroral field-aligned currents; (2) appearance of a localised, intense bulge in the dawnside (04-06 LT) aurora while the midnight sector aurora remained fainter and narrow; and (3) latitudinal broadening and poleward contraction of the nightside aurora, where the poleward motion in this sector is opposite to that expected from a model of the auroral oval's usual oscillation. These observations are interpreted as the response to tail reconnection events, initially involving Vasyliunas-type reconnection of closed mass-loaded magnetotail field lines, and then proceeding onto open lobe field lines, causing the contraction of the polar cap region on the night side.

  1. Wind loads on flat plate photovoltaic array fields. Phase III, final report

    SciTech Connect

    Miller, R.D.; Zimmerman, D.K.

    1981-04-01

    The results of an experimental analysis (boundary layer wind tunnel test) of the aerodynamic forces resulting from winds acting on flat plate photovoltaic arrays are presented. Local pressure coefficient distributions and normal force coefficients on the arrays are shown and compared to theoretical results. Parameters that were varied when determining the aerodynamic forces included tilt angle, array separation, ground clearance, protective wind barriers, and the effect of the wind velocity profile. Recommended design wind forces and pressures are presented, which envelop the test results for winds perpendicular to the array's longitudinal axis. This wind direction produces the maximum wind loads on the arrays except at the array edge where oblique winds produce larger edge pressure loads.

  2. Magnetic field studies of the solar wind interaction with venus from the galileo flyby.

    PubMed

    Kivelson, M G; Kennel, C F; McPherron, R L; Russell, C T; Southwood, D J; Walker, R J; Hammond, C M; Khurana, K K; Strangeway, R J; Coleman, P J

    1991-09-27

    During the 10 February 1990 flyby of Venus, the Galileo spacecraft skimmed the downstream flank of the planetary bow shock. This provided an opportunity to examine both the global and the local structure of the shock in an interval during which conditions in the solar wind plasma were quite steady. The data show that the cross section of the shock in planes transverse to the flow is smaller in directions aligned with the projection of the interplanetary magnetic field than in directions not so aligned. Ultralow-frequency waves were present in the unshocked solar wind, and their amplitude peaked when the spacecraft was downstream of the foreshock. At large distances down the tail, the Mach number of the flow normal to the shock is low, thus providing the opportunity to study repeated crossings of the collisionless shock in an interesting parameter regime. Some of the shock crossings reveal structure that comes close to the theoretically predicted form of intermediate shocks, whose existence in collisionless plasmas has not been confirmed.

  3. Combining Wind-Tunnel and Field Measurements of Street-Canyon Flow via Stochastic Estimation

    NASA Astrophysics Data System (ADS)

    Perret, Laurent; Blackman, Karin; Savory, Eric

    2016-06-01

    We demonstrate how application of the stochastic estimation method can be employed to combine spatially well-resolved wind-tunnel particle image velocimetry measurements with instantaneous velocity signals from a limited number of sensors (six sonic anemometers located within the canyon in the present case) to predict full-scale flow dynamics in an entire street-canyon cross-section. The investigated configuration corresponds to a street-canyon flow in a neutrally stratified atmospheric boundary layer with the oncoming flow being perpendicular to the main canyon axis. Data were obtained during both full-scale and 1:200-scale wind-tunnel experiments. The performance of the proposed method is investigated using both wind-tunnel data and signals from five sonic anemometers to predict the velocity from the sixth one. In particular, based on analysis of the influence of the high-frequency velocity fluctuations on the quality of the reconstruction, it is shown that stochastic estimation is able to correctly reproduce the large-scale temporal features of the flow with the present set-up. The full dataset is then used to spatially extrapolate the instantaneous flow measured by the six sonic anemometers and perform detailed analysis of instantaneous flow features. The main features of the flow, such as the presence of the shear layer that develops over the canyon and the intermittent ejection and penetration events across the canyon opening, are well predicted by stochastic estimation. In addition, thanks to the high spatial resolution made possible by the technique, the intermittency of the main vortical structure existing within the canyon is demonstrated, as well as its meandering motion in the canyon cross-section. It is also shown that the canyon flow, particularly its spanwise component, is affected by large-scale fluctuations of low temporal frequency along the canyon axis. Finally, the proposed techniques based on wind-tunnel data can prove useful for a priori

  4. Simulations of Hurricane Katrina (2005) with the 0.125 degree finite-volume General Circulation Model on the NASA Columbia Supercomputer

    NASA Technical Reports Server (NTRS)

    Shen, B.-W.; Atlas, R.; Reale, O.; Lin, S.-J.; Chern, J.-D.; Chang, J.; Henze, C.

    2006-01-01

    Hurricane Katrina was the sixth most intense hurricane in the Atlantic. Katrina's forecast poses major challenges, the most important of which is its rapid intensification. Hurricane intensity forecast with General Circulation Models (GCMs) is difficult because of their coarse resolution. In this article, six 5-day simulations with the ultra-high resolution finite-volume GCM are conducted on the NASA Columbia supercomputer to show the effects of increased resolution on the intensity predictions of Katrina. It is found that the 0.125 degree runs give comparable tracks to the 0.25 degree, but provide better intensity forecasts, bringing the center pressure much closer to observations with differences of only plus or minus 12 hPa. In the runs initialized at 1200 UTC 25 AUG, the 0.125 degree simulates a more realistic intensification rate and better near-eye wind distributions. Moreover, the first global 0.125 degree simulation without convection parameterization (CP) produces even better intensity evolution and near-eye winds than the control run with CP.

  5. Some Studies in Large-Scale Surface Fluxes and Vertical Motions Associated with Land falling Hurricane Katrina over the Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Reddy, S. R.

    2010-12-01

    We investigated the possible relationship between the large- scale heat fluxes and intensity change associated with the landfall of Hurricane Katrina. After reaching the category 5 intensity on August 28th , 2005 over the central Gulf of Mexico, Katrina weekend to category 3 before making landfall (August 29th , 2005) on the Louisiana coast with the maximum sustained winds of over 110 knots. We also examined the vertical motions associated with the intensity change of the hurricane. The data on Convective Available Potential Energy (CAPE), sea level pressure and wind speed were obtained from the Atmospheric Soundings, and NOAA National Hurricane Center (NHC), respectively for the period August 24 to September 3, 2005. We developed an empirical model and a C++ program to calculate surface potential temperatures and heat fluxes using the above data. We also computed vertical motions using CAPE values. The study showed that the large-scale heat fluxes reached maximum (7960W/m2) with the central pressure 905mb. The Convective Available Potential Energy and the vertical motions peaked 3-5 days before landfall. The large atmospheric vertical motions associated with the land falling hurricane Katrina produced severe weather including thunderstorms and tornadoes.

  6. Monthly mean large-scale analyses of upper-tropospheric humidity and wind field divergence derived from three geostationary satellites

    NASA Technical Reports Server (NTRS)

    Schmetz, Johannes; Menzel, W. Paul; Velden, Christopher; Wu, Xiangqian; Vandeberg, Leo; Nieman, Steve; Hayden, Christopher; Holmlund, Kenneth; Geijo, Carlos

    1995-01-01

    This paper describes the results from a collaborative study between the European Space Operations Center, the European Organization for the Exploitation of Meteorological Satellites, the National Oceanic and Atmospheric Administration, and the Cooperative Institute for Meteorological Satellite Studies investigating the relationship between satellite-derived monthly mean fields of wind and humidity in the upper troposphere for March 1994. Three geostationary meteorological satellites GOES-7, Meteosat-3, and Meteosat-5 are used to cover an area from roughly 160 deg W to 50 deg E. The wind fields are derived from tracking features in successive images of upper-tropospheric water vapor (WV) as depicted in the 6.5-micron absorption band. The upper-tropospheric relative humidity (UTH) is inferred from measured water vapor radiances with a physical retrieval scheme based on radiative forward calculations. Quantitative information on large-scale circulation patterns in the upper-troposphere is possible with the dense spatial coverage of the WV wind vectors. The monthly mean wind field is used to estimate the large-scale divergence; values range between about-5 x 10(exp -6) and 5 x 10(exp 6)/s when averaged over a scale length of about 1000-2000 km. The spatial patterns of the UTH field and the divergence of the wind field closely resemble one another, suggesting that UTH patterns are principally determined by the large-scale circulation. Since the upper-tropospheric humidity absorbs upwelling radiation from lower-tropospheric levels and therefore contributes significantly to the atmospheric greenhouse effect, this work implies that studies on the climate relevance of water vapor should include three-dimensional modeling of the atmospheric dynamics. The fields of UTH and WV winds are useful parameters for a climate-monitoring system based on satellite data. The results from this 1-month analysis suggest the desirability of further GOES and Meteosat studies to characterize

  7. Sea wave modeling with X-band COSMO-SkyMed© SAR-derived wind field forcing and applications in coastal vulnerability assessment

    NASA Astrophysics Data System (ADS)

    Benassai, G.; Montuori, A.; Migliaccio, M.; Nunziata, F.

    2013-03-01

    In this paper, X-band COSMO-SkyMed© synthetic aperture radar (SAR) wind field data are first used to force coastal wind wave modeling for both sea wave numerical simulation and coastal vulnerability assessment purposes. The SAR-based wind field retrieval is accomplished by resolving the SAR-based wind speed and wind direction retrieval problems independently. The sea surface wind speed is retrieved through the azimuth cut-off procedure, and the sea surface wind direction is determined by the multi-resolution analysis of the discrete wavelet transform. The wind wave modeling is based on the third-generation Simulating WAves Nearshore (SWAN) model, which is used for sea wave state estimation in coastal and inland regions. The coastal vulnerability assessment is provided by means of a key parameter, known as impact index, which evaluates the coastal risk due to the inundation of the inshore land. Experiments consist of SWAN numerical simulations run with respect to some relevant wave storms recorded in the southern Tyrrhenian Sea on 2010, with applications in coastal vulnerability assessment along the Sele coastal plain. Experimental results show the benefits of blended wind field products, provided by European Centre for Medium Weather Forecast (ECMWF) model winds and SAR-based wind field estimations, for both wind wave modeling and coastal vulnerability assessment purposes.

  8. Jupiter's Magnetic Field. Magnetosphere, and Interaction with the Solar Wind: Pioneer 11.

    PubMed

    Smith, E J; Davis, L; Jones, D E; Coleman, P J; Colburn, D S; Dyal, P; Sonett, C P

    1975-05-01

    The Pioneer 11 vector helium magnetometer provided precise, contititious measurements of the magnetic fields in interplanetary space, inside Jupiter's magnetosphere, and in the near vicinity of Jupiter. As with the Pioneer 10 data, evidence was seen of the dynanmic interaction of Jupiter with the solar wind which leads to a variety of phenomena (bow shock, upstream waves, nonlinear magnetosheath impulses) and to changes in the dimension of the dayside magnetosphere by as much as a factor of 2. The magnetosphere clearly appears to be blunt, not disk-shaped, with a well-defined outer boundary. In the outer magnetosphere, the magnetic field is irregular but exhibits a persistent southward component indicative of a closed magnetosphere. The data contain the first clear evidence in the dayside magnetosphere of the current sheet, apparently associated with centrifugal forces, that was a donminatnt feature of the outbound Pionieer 10 data. A modest westward spiraling of the field was again evident inbound but not outbound at higher latitudes and nearer the Sun-Jupiter direction. Measurements near periapsis, which were nearer the planet and provide better latitude and longitude coverage than Pioneer 10, have revealed a 5 percent discrepancy with the Pioneer 10 offset dipole mnodel (D(2)). A revised offset dipole (6-parameter fit) is presented as well as the results of a spherical harmonic analysis (23 parameters) consisting of an interior dipole, quadrupole, and octopole and an external dipole and quadrupole. The dipole moment and the composite field appear moderately larger than inferred from Pioneer 10. Maximum surface fields of 14 and 11 gauss in the northern and southern hemispheres are inferred. Jupiter's planetary field is found to be slightly more irregular than that of Earth.

  9. An analysis of wintertime surface wind fields in the Upper Green River Basin of Sublette County, Wyoming

    NASA Astrophysics Data System (ADS)

    Emery, Brittni R.

    Observations of high ozone mixing ratios in Sublette County, Wyoming, recently resulted in the region being designated to be in marginal non-attainment of the National Ambient Air Quality Standard (NAAQS) for ozone. Many interrelated factors influence the frequency and extent of elevated ozone episodes, including meteorological factors, through their effect on pollutant dilution and dispersion. Surface wind field patterns in the Upper Green River Basin (UGRB) of Sublette County, Wyoming, were therefore examined using observations from a network of surface monitoring stations for 2011, when many ozone episodes occurred, and for 2012, when, in contrast, there were none. The synoptic conditions associated with each pattern are described using output from the North American Mesoscale (NAM) model. Five patterns are described. They confirm that elevated ozone is often associated with light and variable winds. However, there are also days when moderate afternoon southeasterly flow leads to observations of elevated ozone on the west side of the basin. These southeasterly winds are identified as barrier winds caused by southwesterly flow at 700mb. Recognition of this wind pattern facilitates future forecasting of periods likely to experience potentially elevated ozone in the region. The merit of adding additional monitoring sites from the Upper Green River Basin Wintertime Ozone Wind Field Investigation (O3w) and the Upper Green River Ozone Study (UGWOS) of 2012 to the current monitoring network is also discussed.

  10. Field measurements of wind speed and reconfiguration in Arundo donax (Poaceae) with estimates of drag forces.

    PubMed

    Speck, Olga

    2003-08-01

    The giant reed (Arundo donax) is well known as a species that can withstand high wind loads without mechanical damage. To examine wind impact, profiles of vertical wind speeds in the plant's natural habitat (southern France) were measured at the edge and within a stand in the main wind direction. Wind speed was recorded simultaneously at five heights. For 75 measurements of within-canopy wind speed profiles, the attenuation coefficient was 4.4 ± 0.5, a value typical for plant stands with very dense canopies. Video recordings proved that A. donax becomes streamlined with increasing wind speed, reducing the projected surface area of leaves and stem. The total projected surface area is a function of wind speed and can be characterized by a second-order polynomial regression curve. For small wind velocities up to 1 m/s, the calculated drag force is proportional to the square of the wind speed. However, when A. donax plants are subjected to higher wind speeds (1.5-10 m/s), the drag force becomes directly proportional to the wind speed. Streamlining is a potentially important adaptation for withstanding high wind loads, especially for individual plants and plants at the edge of stands, whereas in dense stands streamlining probably plays a minor role.

  11. Visualization study on the static flow field around a straight-bladed vertical axis wind turbine

    NASA Astrophysics Data System (ADS)

    Li, Yan; Tagawa, Kotaro

    2010-03-01

    Visual experiments based on the smoke wire way were carried out on a small model of Straight-blade Vertical Axis Wind Turbine (SB-VAWT) to invest the relationship between the static flow field characteristics and the rotor azimuth angle. The test rotor had 3 blades with NACA0018 aerofoil. The rotor diameter and blade chord were 0.3m and 0.07m, respectively. Visual photos of the static flow path lines in and around the rotor were obtained at every 5 degrees of the azimuth angle. Further, numerical computations of the static flow filed were also carried out for comparison with the same situation as the visual tests and the static torques at different azimuth angles were calculated. According to the results of visual tests and computations, the dependence of the starting performance on the azimuth angle was discussed. The solidity is an important factor affecting the starting performance of the SB-VAWT.

  12. Visualization study on the static flow field around a straight-bladed vertical axis wind turbine

    NASA Astrophysics Data System (ADS)

    Li, Yan; Tagawa, Kotaro

    2009-12-01

    Visual experiments based on the smoke wire way were carried out on a small model of Straight-blade Vertical Axis Wind Turbine (SB-VAWT) to invest the relationship between the static flow field characteristics and the rotor azimuth angle. The test rotor had 3 blades with NACA0018 aerofoil. The rotor diameter and blade chord were 0.3m and 0.07m, respectively. Visual photos of the static flow path lines in and around the rotor were obtained at every 5 degrees of the azimuth angle. Further, numerical computations of the static flow filed were also carried out for comparison with the same situation as the visual tests and the static torques at different azimuth angles were calculated. According to the results of visual tests and computations, the dependence of the starting performance on the azimuth angle was discussed. The solidity is an important factor affecting the starting performance of the SB-VAWT.

  13. Effect of sudden solar wind dynamic pressure changes at subauroral latitudes - Change in magnetic field

    NASA Technical Reports Server (NTRS)

    Le, G.; Russell, C. T.; Petrinec, S. M.; Ginskey, M.

    1993-01-01

    The observations obtained during the International Magnetospheric Study (IMS) from the magnetometers of the IGS network extending from Cambridge, England, to Tromso, Norway, are used to study the response of subauroral current systems to sudden changes in solar wind dynamic pressure. Observations show that the response is very strong at subauroral latitudes. The preliminary response in the H component is a brief, small increase in the dayside morning sector and a decrease in the aftenoon and night sectors. The main response in the horizontal field (the H and D components) is toward the pole except in the dayside morning sector. The inferred ionospheric current is mainly a circulatory system flowing counterclockwise when viewed from the north pole everywhere at subauroral latitudes except the dayside morning sector.

  14. Plasma β scaling of anisotropic magnetic field fluctuations in the solar wind flux tube

    SciTech Connect

    Sarkar, Aveek; Bhattacharjee, Amitava; Ebrahimi, Fatima E-mail: amitava@princeton.edu

    2014-03-10

    Based on various observations, it has been suggested that at 1 AU, solar wind consists of 'spaghetti'-like magnetic field structures that have the magnetic topology of flux tubes. It is also observed that the plasma fluctuation spectra at 1 AU show a plasma β dependence. Reconciling these two sets of observations and using the Invariance Principle, Bhattacharjee et al. suggested that the plasma inside every flux tube may become unstable with respect to pressure-driven instabilities and gives rise to fluctuation spectra that depend on the local plasma β. The present work is the first direct numerical simulation of such a flux tube. We solve the full magnetohydrodynamic equations using the DEBS code and show that if the plasma inside the flux tube is driven unstable by spatial inhomogeneities in the background plasma pressure, the observed nature of the fluctuating power spectra agrees reasonably well with observations, as well as the analytical prediction of Bhattacharjee et al.

  15. Salt marsh retreat induced by wind waves: experiments, field and modeling

    NASA Astrophysics Data System (ADS)

    Solari, L.; Francalanci, S.; Bendoni, M.; Cappietti, L.

    2013-12-01

    Edge erosion of salt marshes due to surface waves and tide forcing is likely the chief mechanism that models marsh boundaries and by which salt marshes in worldwide areas are being lost. To address this problem, an experimental investigation in a laboratory flume and field measurements collected in the lagoon of Venice were conducted to understand the main processes controlling marsh edge retreat with a focus on the erosion mechanisms caused by the impact of wind waves in the case of various tidal levels. A physical model reproducing a salt marsh bank was built inside a long wave current flume where random surface waves have been generated according to a given wave spectrum. The physical model was constructed with the original soil of salt marshes from the Venice Lagoon, while the wave climate was reproduced according to field measurements. In order to reveal the effect of vegetation on bank stability, two identical banks were built but for the inclusion of halophytic plants. A first set of experiments was conducted reproducing only tidal waves, a second set with wind waves superimposed to the tide. A third set o f experiments were aimed to investigate the dynamic impact and transmission of the waves on and within the bank. The following quantities were collected during the experiments: water content and pore water pressure inside the bank, water levels and velocities at various distances from the bank, dynamic pressures on the bank edge surface and internal pressure fluctuations due to wave impact. Bank geometry profile and bottom topography at different times have also been collected to characterize the erosion rate with time and the evolution of bank retreat. Two types of mass failures were observed during the experiments: slides and toppling failures. The latter were most frequently observed failures, consisting in the toppling of blocks and were often the consequence of the presence of deep tension cracks. In most cases the impact of wind waves caused the

  16. Effect of sudden solar wind dynamic pressure changes at subauroral latitudes: Change in magnetic field

    SciTech Connect

    Le, G.; Russell, C.T.; Petrinec, S.M.; Ginskey, M. )

    1993-03-01

    The observations obtained during the International Magnetospheric Study (IMS) from the magnetometers of the IGS network extending from Cambridge, England, to Tromso, Norway, are used to study the response of subauroral current systems to sudden changes in solar wind dynamic pressure. Observations show that the response is very strong at subauroral latitudes. The preliminary response in the H component is a brief, small increase in the dayside moring sector and a decrease in the afternoon and night sectors. The main response in the horizontal field (the H and D components) is toward the pole except in the dayside morning sector. The inferred ionospheric current is mainly a circulatory system flowing counterclockwise when viewed form the north pole everywhere at subauroral latitudes except the dayside morning sector. 29 refs., 12 figs.

  17. The proton temperature and the total hourly variance of the magnetic field components in different solar wind speed regions

    NASA Technical Reports Server (NTRS)

    Tu, Chuan-Yi; Freeman, John W.; Lopez, R. E.

    1989-01-01

    A comparison has been made between the predictions of the theory for radial variations of both Alfvenic fluctuations and solar wind proton temperatures proposed by Tu (1987, 1988) and the statistical results of hourly averaged plasma and magnetic field data observed by Helios 1 and 2 from launch through 1980 for different solar wind speed regimes. The comparison shows that for speed ranges between 500-800 km/s, the radial variation of the proton temperature between 0.3 and 1 AU can be explained by heating from the cascade energy which is determined by the radial variation of the total variance of magnetic field vector.

  18. Improving the predictions of solar wind speed and interplanetary magnetic field at the Earth

    NASA Astrophysics Data System (ADS)

    Tran, Tham

    2009-09-01

    The Wang-Sheeley-Arge (WSA) model, an advanced version of the potential field source surface (PFSS) model, is widely used to predict the solar wind speed (SWS) and the interplanetary magnetic field (IMF) polarities at the Earth. The results, however, do not always match the observations. To improve the predictive capability of this model we made the following changes: (1) We used the high resolution magnetograms produced by the Michelson Doppler Imager (MDI) aboard the Solar and Heliospheric Observer (SOHO) spacecraft. We properly calibrated the magnetic field strength of the MDI observations using the Mt. Wilson (MWO) FeI magnetograms so that each MDI level 1.8 magnetogram can be converted to the same basis as the saturation-corrected long-duration MWO Fel magnetogram. (2) The WSA model requires a map of full solar surface magnetic field, and traditionally a synoptic chart is used. However, the synoptic chart does not represent the full solar surface at a particular time. Therefore, we suggest to use a new format called heliospheric (or snapshot) map in the model. (3) We implement a better estimate of the polar field that is not observable during some part of the year due to the solar tilted angle B0. The magnetic field near the solar poles is very important because it may be the dominant part of the solar magnetic field far away from the Sun, especially during the period of solar minimum. (4) The WSA model assumes that the solar photospheric magnetic field is nearly radial, so that its radial component can be obtained directly from the line-of-sight (LOS) of the observed field. This approach produces very strong radial magnetic field near the solar poles. We solve this problem by first obtaining the spherical harmonic coefficients directly from the LOS magnetic data and then reconstructing the radial magnetic chart. (5) Finally, changing the radius of the source surface, rss, in the PFSS analysis strongly affects the predicted SWS and IMF at the Earth. Our

  19. Ion and neutral polar winds for northward interplanetary magnetic field conditions

    NASA Astrophysics Data System (ADS)

    Gardner, Larry C.; Schunk, Robert W.

    2006-08-01

    The coupling of the ionosphere/magnetosphere system at high-latitudes is dependent in part upon the transport of neutral atoms from the ionosphere to the magnetosphere, and visa versa. The neutral atoms that flow between the ionosphere and the magnetosphere are neutral stream atoms that are produced in charge exchange reactions between the ions in the polar wind and the background thermal and geocoronal atoms. The characteristics of these neutral stream particles are highly dependent upon the ions in the polar cap. The ions are convected across the polar cap due to convection electric fields, and thus the neutral stream particles are also indirectly affected by the convection electric fields due to charge exchange. The horizontal flow of neutral stream particles, therefore, shows a general anti-sunward motion during periods of southward interplanetary magnetic field (IMF), and a general sunward flow across the magnetic pole during times of northward IMF. The vertical fluxes of these neutral stream particles depend upon several processes, including the heat input due to precipitating electrons, the vertical velocity of the ions involved in the charge exchange reactions that produce the neutral stream particles, and the time history of neutral stream particles in the high-latitude region.

  20. The deep Madden Field, a super-deep Madison gas reservoir, Wind River Basin, Wyoming

    SciTech Connect

    Moore, C.H. ); Hawkins, C. )

    1996-01-01

    Madison dolomites form the reservoir of a super deep, potential giant sour gas field developed on the Madden Anticline immediately in front of the Owl Creek Thrust along the northern rim of the Wind River Basin, central Wyoming. The Madison reservoir dolomites are presently buried to some 25,000 feet at Madden Field and exhibit porosity in excess of 15%. An equivalent dolomitized Madison sequence is exposed in outcrop only 5 miles to the north on the hanging wall of the Owl Creek thrust at Lysite Mountain. Preliminary comparative stratigraphic, geochemical and petrologic data, between outcrop and available cores and logs at Deep Madden suggests: (1) early, sea level-controlled, evaporite-related dolomitization of the reservoir and outcrop prior to significant burial; (2) both outcrop and deep reservoir dolomites underwent significant recrystallization during a common burial history until their connection was severed during Laramide faulting in the Eocene; (3) While the dolomite reservoir at Madden suffered additional diagenesis during an additional 7-10 thousand feet of burial, the pore systems between outcrop and deep reservoir are remarkably similar. The two existing deep Madison wells at Madden are on stream, with a third deep Madison well currently drilling. The sequence stratigraphic framework and the diagenetic history of the Madison strongly suggests that outcrops and surface cores of the Madison in the Owl Creek Mountains will be useful in further development and detailed reservoir modeling of the Madden Deep Field.

  1. The deep Madden Field, a super-deep Madison gas reservoir, Wind River Basin, Wyoming

    SciTech Connect

    Moore, C.H.; Hawkins, C.

    1996-12-31

    Madison dolomites form the reservoir of a super deep, potential giant sour gas field developed on the Madden Anticline immediately in front of the Owl Creek Thrust along the northern rim of the Wind River Basin, central Wyoming. The Madison reservoir dolomites are presently buried to some 25,000 feet at Madden Field and exhibit porosity in excess of 15%. An equivalent dolomitized Madison sequence is exposed in outcrop only 5 miles to the north on the hanging wall of the Owl Creek thrust at Lysite Mountain. Preliminary comparative stratigraphic, geochemical and petrologic data, between outcrop and available cores and logs at Deep Madden suggests: (1) early, sea level-controlled, evaporite-related dolomitization of the reservoir and outcrop prior to significant burial; (2) both outcrop and deep reservoir dolomites underwent significant recrystallization during a common burial history until their connection was severed during Laramide faulting in the Eocene; (3) While the dolomite reservoir at Madden suffered additional diagenesis during an additional 7-10 thousand feet of burial, the pore systems between outcrop and deep reservoir are remarkably similar. The two existing deep Madison wells at Madden are on stream, with a third deep Madison well currently drilling. The sequence stratigraphic framework and the diagenetic history of the Madison strongly suggests that outcrops and surface cores of the Madison in the Owl Creek Mountains will be useful in further development and detailed reservoir modeling of the Madden Deep Field.

  2. Nacelle LiDAR online wind field reconstruction applied to feedforward pitch control

    NASA Astrophysics Data System (ADS)

    GUILLEMIN, F.; DOMENICO, D. DI; NGUYEN, N.; SABIRON, G.; BOQUET, M.; GIRARD, N.; COUPIAC, O.

    2016-09-01

    This paper presents innovative filtering and reconstruction techniques of nacelle LiDAR data, and exploitation of obtained wind anticipation capabilities for wind turbine control strategy. The implemented algorithms are applied under industrial constraints, on a MAIA EOLIS wind turbine, equipped with a LEOSPHERE 5-beams pulsed LiDAR, during experimental campaigns of SMARTEOLE collaborative project.

  3. Break-up of New Orleans Households after Hurricane Katrina

    PubMed Central

    Rendall, Michael S.

    2011-01-01

    Theory and evidence on disaster-induced population displacement have focused on individual and population-subgroup characteristics. Less is known about impacts on households. I estimate excess incidence of household break-up due to Hurricane Katrina by comparing a probability sample of pre-Katrina New Orleans resident adult household heads and non–household heads (N = 242), traced just over a year later, with a matched sample from a nationally representative survey over an equivalent period. One in three among all adult non–household heads, and one in two among adult children of household heads, had separated from the household head 1 year post-Katrina. These rates were, respectively, 2.2 and 2.7 times higher than national rates. A 50% higher prevalence of adult children living with parents in pre-Katrina New Orleans than nationally increased the hurricane’s impact on household break-up. Attention to living arrangements as a dimension of social vulnerability in disaster recovery is suggested. PMID:21709733

  4. Hurricane Katrina: Maternal Depression Trajectories and Child Outcomes

    PubMed Central

    Lai, Betty S.; Tiwari, Ashwini; Beaulieu, Brooke A.; Self-Brown, Shannon; Kelley, Mary Lou

    2015-01-01

    Background The authors examined depression trajectories over two years among mothers exposed to Hurricane Katrina. Risk and protective factors for depression trajectories, as well as associations with child outcomes were analyzed. Method This study included 283 mothers (age at time 1, M = 39.20 years, SD = 7.21; 62% African American). Mothers were assessed at four time points over two years following Hurricane Katrina. Mothers reported posttraumatic stress symptoms, hurricane exposure, traumatic life events, and social support at time 1. Depressive symptoms were modeled at times 2, 3, and 4. Youth reported their distress symptoms (posttraumatic stress, depression, and anxiety) at time 4. Results Latent class growth analyses identified three maternal depression trajectories among mothers exposed to Hurricane Katrina: low (61%), resilient (29%), and chronic (10%). Social support was identified as a protective factor among mothers. Conclusions Three main trajectories of maternal depression following Hurricane Katrina were identified. Social support was protective for mothers. Identified trajectories were not associated with children’s distress outcomes. These results have implications for disaster responses, screening efforts, and interventions targeted towards families. Future studies warrant the investigation of additional risk and protective factors that can affect maternal and child outcomes. PMID:26752938

  5. Children Displaced by Hurricane Katrina: A Focus Group Study

    ERIC Educational Resources Information Center

    Pfefferbaum, Betty; Houston, J. Brian; Wyche, Karen Fraser; Van Horn, Richard L.; Reyes, Gilbert; Jeon-Slaughter, Haekyung; North, Carol S.

    2008-01-01

    Focus groups were conducted with 23 children and adolescents, aged 9 to 17 years, who relocated from Louisiana to Texas following Hurricane Katrina to explore their disaster, evacuation, and resettlement experiences. The resilience described by some was remarkable and, despite evidence of cultural disparity and stigma, many identified positive…

  6. Stress and Support in Family Relationships after Hurricane Katrina

    ERIC Educational Resources Information Center

    Reid, Megan; Reczek, Corinne

    2011-01-01

    In this article, the authors merge the study of support, strain, and ambivalence in family relationships with the study of stress to explore the ways family members provide support or contribute to strain in the disaster recovery process. The authors analyze interviews with 71 displaced Hurricane Katrina survivors, and identify three family…

  7. SIMULATING LAKE PONTCHARTRAIN AND MISSISSIPPI RIVER OUTFLOW AFTER HURRICANE KATRINA

    EPA Science Inventory

    Hurricane Katrina was the direct cause of the flooding of New Orleans in September 2005. Between its passage and the pumping of flood waters back into Lake Pontchartrain and the Mississippi River, the flood waters acquired considerable amounts of contaminants, notably silver, but...

  8. Katrina Kids! Helping Kids Exposed to Population-Wide Trauma

    ERIC Educational Resources Information Center

    Bender, William N.; Sims, Rebecca

    2007-01-01

    Although schools have implemented school safety plans as a result of the violence witnessed on rare occasions in schools today, schools are less likely to be prepared for emergencies such as Katrina or 9/11; this is true even for schools in locations prone to hurricanes, tornadoes, or earthquakes. Whereas disaster plans typically involve school…

  9. Resilience of Professional Counselors Following Hurricanes Katrina and Rita

    ERIC Educational Resources Information Center

    Lambert, Simone F.; Lawson, Gerard

    2013-01-01

    Professional counselors who provided services to those affected by Hurricanes Katrina and Rita completed the K6+ (screen for severe mental illness), the Posttraumatic Growth Inventory, and the Professional Quality of Life Scale. Results indicated that participants who survived the hurricanes had higher levels of posttraumatic growth than…

  10. Academic and Student Affairs Issues Post Hurricane Katrina

    ERIC Educational Resources Information Center

    Jarrell, Camille; Dennis, Raymonda; Jackson, Marian; Kenney, Cynthia A.

    2008-01-01

    This article describes several issues in the academic and student affairs areas faced by students and faculty in the post-Katrina destruction environment. Cases are used to illustrate the issues, and a call is made for increased disaster readiness plans.

  11. Telling Katrina Stories: Problems and Opportunities in Engaging Disaster

    ERIC Educational Resources Information Center

    Bowman, Michael S.; Bowman, Ruth Laurion

    2010-01-01

    As the fifth anniversary of life-changing events like Hurricanes Katrina and Rita approaches, the authors talk about the problems those who reside at the site of the disaster face in keeping those events alive in public memory and in making them an ongoing issue for deliberation in the public sphere. In short, then, the authors address the…

  12. New Orleans Colleges Slog toward Recovery from Katrina

    ERIC Educational Resources Information Center

    Mangan, Katherine

    2008-01-01

    Twenty-eight months after Hurricane Katrina forced the closures of more than a half-dozen New Orleans colleges and universities, many of them are still struggling to regain their enrollments and restore buildings damaged by floodwater and mold. Over all, college enrollment in New Orleans increased slightly in the fall of 2007, reaching 74 percent…

  13. Coping with a Man-Made Crisis: Lessons from Katrina

    ERIC Educational Resources Information Center

    Cowen, Scott S.

    2009-01-01

    In the fall of 2005, Tulane University responded to Katrina's devastation by undertaking a significant re-envisioning of the university's mission and strategy. Tulane needed to survive financially without sacrificing the core academic strengths that have drawn so many students to them: a holistic undergraduate experience that leverages the…

  14. Post-Katrina Fixes Really Drive Home Our Humanity

    ERIC Educational Resources Information Center

    Hardy, Lawrence

    2006-01-01

    Using the diary of Kim Stasny, superintendent of the Bay St. Louis-Waveland School District in Mississippi, and accounts from other superintendents from areas affected by Hurricane Katrina, the author describes the grim situation faced by schools in the days and weeks after the storm struck. He then discusses the importance of getting students…

  15. Change in Chaos: Seven Lessons Learned from Katrina

    ERIC Educational Resources Information Center

    Carr-Chellman, Alison A.; Beabout, Brian; Alkandari, Khaled A.; Almeida, Luis C.; Gursoy, Husra T.; Ma, Ziyan; Modak, Rucha S.; Pastore, Raymond S.

    2008-01-01

    This article discusses seven lessons learned from Katrina, suggesting that after chaos: (1) there is hope; (2) there is a strong atmosphere of indeterminacy; (3) things tend to break apart and reform in somewhat similar ways but with different values; (4) there is a desire for organization, leadership, and familiarity; (5) there is a sense of…

  16. Community College Re-Enrollment after Hurricane Katrina

    ERIC Educational Resources Information Center

    Lowe, Sarah R.; Rhodes, Jean E.

    2013-01-01

    In this study, we explored predictors of community college re-enrollment after Hurricane Katrina among a sample of low-income women (N = 221). It was predicted that participants' pre-hurricane educational optimism would predict community college re-enrollment a year after the hurricane. The influence of various demographic and additional resources…

  17. Wading in the waters: spirituality and older black Katrina survivors.

    PubMed

    Lawson, Erma Jean; Thomas, Cecelia

    2007-05-01

    Hurricane Katrina has drawn increased interest in coping strategies, spirituality, and mental health among low-income Blacks. Given the paucity of information available regarding the role of spirituality in surviving Hurricane Katrina, this qualitative study explores active coping strategies of older Blacks. Older respondents who were evacuated to a Texas retirement apartment complex participated in a series of three in-depth interviews (starting approximately three weeks after their arrival in the host state and continuing weekly). Without exception, the findings indicate that this population coped with Katrina and its aftermath through reliance on a Higher Power. The relationship to a Higher Power did not necessarily translate into church membership. The conclusions of the respondents' spiritual coping mechanisms revealed the following themes: 1) regular communication with a supernatural power; 2) miracles of faith through this source of guidance and protection; 3) daily reading of the Bible and various spiritual and devotional materials; and 4) helping others as a consequence of faith and devotion to a supreme being. This study indicates that spirituality promotes emotional resilience in the aftermath of traumatic events such as Hurricane Katrina. These findings also point to the need for researchers to reconsider expressions of spirituality based solely on church membership/attendance and prayer, and to consider redefining spiritual coping as a form of cultural capital.

  18. Effect of Hurricane Katrina on the mortality of dialysis patients.

    PubMed

    Kutner, Nancy G; Muntner, Paul; Huang, Yijian; Zhang, Rebecca; Cohen, Andrew J; Anderson, Amanda H; Eggers, Paul W

    2009-10-01

    To investigate whether Hurricane Katrina's landfall in August 2005 resulted in excess mortality, we conducted a cohort study of patients who started dialysis between January 2003 and late August 2005 and who received treatment at 94 Katrina-affected clinics in the area. Survival, regardless of patient location after the storm, was followed through February 2006. In adjusted Cox proportional hazards models, Hurricane Katrina (time-varying indicator) was not significantly associated with mortality risk for patients from regions of the Gulf Coast affected by Katrina or those from a subset of 40 New Orleans clinics. Subgroup analyses indicated no significant increased mortality risk by race, income status, or dialysis modality. Sensitivity analyses indicated no significant increased mortality risk for patients from clinics closed for 10 days or longer, patients in their first 90 days of dialysis, or patients not evacuated from the affected areas. Patients remaining in the New Orleans area may have been more vulnerable due to age and comorbidities; however, the change in their mortality risk in the month following the storm was not statistically significant. We suggest that disaster-related education for patients must be ongoing, and that each disaster may present a different set of circumstances and challenges that will require unanticipated response efforts.

  19. Comment on "Wetland sedimentation from hurricanes Katrina and Rita".

    PubMed

    Törnqvist, Torbjörn E; Paola, Chris; Parker, Gary; Liu, Kam-Biu; Mohrig, David; Holbrook, John M; Twilley, Robert R

    2007-04-13

    Turner et al. (Reports, 20 October 2006, p. 449) measured sedimentation from Hurricanes Katrina and Rita in coastal Louisiana and inferred that storm deposition overwhelms direct Mississippi River sediment input. However, their annualized hurricane deposition rate is overestimated, whereas riverine deposition is underestimated by at least an order of magnitude. Their numbers do not provide a credible basis for decisions about coastal restoration.

  20. Experience of Hurricane Katrina and Reported Intimate Partner Violence

    ERIC Educational Resources Information Center

    Harville, Emily W.; Taylor, Catherine A.; Tesfai, Helen; Xiong, Xu; Buekens, Pierre

    2011-01-01

    Intimate partner violence (IPV) has been associated with stress, but few studies have examined the effect of natural disaster on IPV. In this study, the authors examine the relationship between experience of Hurricane Katrina and reported relationship aggression and violence in a cohort of 123 postpartum women. Hurricane experience is measured…

  1. Controlling Influence of Magnetic Field on Solar Wind Outflow: An Investigation using Current Sheet Source Surface Model

    NASA Astrophysics Data System (ADS)

    Poduval, Bala

    2016-05-01

    The Wang and Sheeley empirical relationship between magnetic flux tube expansion (FTE) in the inner corona and the solar wind speed (SWS) observed near the Earth's orbit forms the basis of current solar wind prediction techniques such as WSA/ENLIL. Based on this concept, the Current Sheet Source Surface (CSSS) model, built on a corona in magnetostatic equilibrium incorporating electric currents, has recently been validated for solar wind prediction. We present the initial results of an investigation of the influence of solar magnetic field in determining the solar wind outflow using the CSSS model. We found that there is significant temporal variation in the functional form of FTE--SWS relation and that the accuracy of CSSS predictions are nearly twice better than the PFSS predcitions. We attribute the greater accuracy of CSSS predictions to the model's capability to trace the solar wind sources better than the PFSS model and, perhaps, the treatment of electric currents in the inner corona in the CSSS model.Synoptic maps of coronal magnetic field, similar to the photospheric ones, are still a long way away, though techniques are under development, especially using the Coronal Multi-Channel Polarimeter data. And the near--Sun regions below 0.3 AU remain unexplored until Solar Probe Plus and Solar Orbiter are launched. A well-validated model of the corona capable of providing reliable solar wind conditions in the near-Sun region will be of great use in interpreting the data collected by these spacecraft. The magnetohydrodynamic models such as ENLIL for space weather prediction, require ambient plasma and magnetic field information at their inner boundaries, usually provided by magnetostatic models, such as PFSS, in the absence of sufficient observational data. Our present work is an attempt to provide methods to generate reliable solar wind conditions in the near-Sun region.

  2. Anomalous Shocks on the Measured Near-Field Pressure Signatures of Low-Boom Wind-Tunnel Models

    NASA Technical Reports Server (NTRS)

    Mack, Robert J.

    2006-01-01

    Unexpected shocks on wind-tunnel-measured pressure signatures prompted questions about design methods, pressure signature measurement techniques, and the quality of measurements in the flow fields near lifting models. Some of these unexpected shocks were the result of component integration methods. Others were attributed to the three-dimension nature of the flow around a lifting model, to inaccuracies in the prediction of the area-ruled lift, or to wing-tip stall effects. This report discusses the low-boom model wind-tunnel data where these unexpected shocks were initially observed, the physics of the lifting wing/body model's flow field, the wind-tunnel data used to evaluate the applicability of methods for calculating equivalent areas due to lift, the performance of lift prediction codes, and tip stall effects so that the cause of these shocks could be determined.

  3. A microcomputer program for estimating low altitude wind and turbulence fields

    NASA Technical Reports Server (NTRS)

    Ludwig, F. L.; Lester, Peter

    1991-01-01

    Past efforts to develop methods for objective wind analysis and to provide turbulence estimates to pilots are reviewed. The present approach involves a wind module and a turbulence module. The wind module extends the critical dividing streamline concept and past developments in mass-conserving wind interpolation schemes. The turbulence module is based on recent efforts to develop practical atmospheric turbulence parameterization schemes based on lapse rate, wind shear, surface heating, and surface roughness. The lapse rate and wind shear are readily obtained from the wind module. Surface roughness and heating come from land use information and net radiation estimates derived from cloud cover, terrain slope, local time, and latitude. This system is argued to have considerable potential for providing useful online information for many kinds of aircraft operations.

  4. Race, socioeconomic status, and return migration to New Orleans after Hurricane Katrina.

    PubMed

    Fussell, Elizabeth; Sastry, Narayan; Vanlandingham, Mark

    2010-01-01

    Hurricane Katrina struck New Orleans on the 29th of August 2005 and displaced virtually the entire population of the city. Soon after, observers predicted the city would become whiter and wealthier as a result of selective return migration, although challenges related to sampling and data collection in a post-disaster environment have hampered evaluation of these hypotheses. In this article, we investigate return to the city by displaced residents over a period of approximately 14 months following the storm, describing overall return rates and examining differences in return rates by race and socioeconomic status. We use unique data from a representative sample of pre-Katrina New Orleans residents collected in the Displaced New Orleans Residents Pilot Survey. We find that black residents returned to the city at a much slower pace than white residents even after controlling for socioeconomic status and demographic characteristics. However, the racial disparity disappears after controlling for housing damage. We conclude that blacks tended to live in areas that experienced greater flooding and hence suffered more severe housing damage which, in turn, led to their delayed return to the city. The full-scale survey of displaced residents being fielded in 2009-2010 will show whether the repopulation of the city was selective over a longer period.

  5. Engaging non-Majors: Teaching From the Eye of Hurricane Katrina and the Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Sarmiento, S. E.

    2007-12-01

    Engaging non-majors to become interested in the geosciences college courses they take for a science requirement represents a challenge. These courses are most likely the only exposure they will ever have to a formal earth science curriculum. Experience shows a general lack of motivation and the need to find effective teaching methods to raise their interest. In the beginning of the fall 2005 semester, I participated in a research project to measure water vapor contents on the ground of the eye of hurricane Katrina in Slidell, Louisiana. Sharing this experience with my physical and environmental geology students made a significant difference (25 percentage final grade improvement) on their interest and course performance over previous semesters. Class presentations with data collected in Katrina contributed to build a general trust in the instructor and in the way, students viewed the role of geosciences in the mitigation of natural hazardous processes. The use of travel blogs and internet enhanced courses allows teaching real time from almost anywhere as it was recently done from the east pacific (360 miles NW from Guam). An interactive portfolio of the faculty field experiences presented at the beginning of the semester has the potential to build student interest and their trust on the faculty experience and passion for the subject.

  6. THREE-DIMENSIONAL {integral} FIELD OBSERVATIONS OF 10 GALACTIC WINDS. I. EXTENDED PHASE ({approx}>10 Myr) OF MASS/ENERGY INJECTION BEFORE THE WIND BLOWS

    SciTech Connect

    Sharp, R. G.; Bland-Hawthorn, J. E-mail: jbh@physics.usyd.edu.a

    2010-03-10

    In recent years, we have come to recognize the widespread importance of large-scale winds in the life cycle of galaxies. The onset and evolution of a galactic wind is a highly complex process which must be understood if we are to understand how energy and metals are recycled throughout the galaxy and beyond. Here we present three-dimensional spectroscopic observations of a sample of 10 nearby galaxies with the AAOmega-SPIRAL {integral}-field spectrograph on the 3.9 m Anglo-Australian Telescope, the largest survey of its kind to date. The double-beam spectrograph provides spatial maps in a range of spectral diagnostics: [O III]5007, Hbeta, Mg b, Na D, [O I]6300, Halpha, [N II]6583, [S II]6717, 6731. We demonstrate that these flows can often separate into highly ordered structures through the use of ionization diagnostics and kinematics. All of the objects in our survey show extensive wind-driven filamentation along the minor axis, in addition to large-scale disk rotation. Our sample can be divided into either starburst galaxies or active galactic nuclei (AGNs), although some objects appear to be a combination of these. The total ionizing photon budget available to both classes of galaxies is sufficient to ionize all of the wind-blown filamentation out to large radius. We find, however, that while AGN photoionization always dominates in the wind filaments, this is not the case in starburst galaxies where shock ionization dominates. This clearly indicates that after the onset of star formation, there is a substantial delay ({approx}>10 Myr) before a starburst wind develops. We show why this behavior is expected by deriving 'ionization' and dynamical timescales for both AGNs and starbursts. We establish a sequence of events that lead to the onset of a galactic wind. The clear signature provided by the ionization timescale is arguably the strongest evidence yet that the starburst phenomenon is an impulsive event. A well-defined ionization timescale is not expected in

  7. Bats Avoid Radar Installations: Could Electromagnetic Fields Deter Bats from Colliding with Wind Turbines?

    PubMed Central

    Nicholls, Barry; Racey, Paul A.

    2007-01-01

    Large numbers of bats are killed by collisions with wind turbines, and there is at present no direct method of reducing or preventing this mortality. We therefore determine whether the electromagnetic radiation associated with radar installations can elicit an aversive behavioural response in foraging bats. Four civil air traffic control (ATC) radar stations, three military ATC radars and three weather radars were selected, each surrounded by heterogeneous habitat. Three sampling points matched for habitat type and structure, dominant vegetation species, altitude and surrounding land class were located at increasing distances from each station. A portable electromagnetic field meter measured the field strength of the radar at three distances from the source: in close proximity (<200 m) with a high electromagnetic field (EMF) strength >2 volts/metre, an intermediate point within line of sight of the radar (200–400 m) and with an EMF strength <2 v/m, and a control site out of sight of the radar (>400 m) and registering an EMF of zero v/m. At each radar station bat activity was recorded three times with three independent sampling points monitored on each occasion, resulting in a total of 90 samples, 30 of which were obtained within each field strength category. At these sampling points, bat activity was recorded using an automatic bat recording station, operated from sunset to sunrise. Bat activity was significantly reduced in habitats exposed to an EMF strength of greater than 2 v/m when compared to matched sites registering EMF levels of zero. The reduction in bat activity was not significantly different at lower levels of EMF strength within 400 m of the radar. We predict that the reduction in bat activity within habitats exposed to electromagnetic radiation may be a result of thermal induction and an increased risk of hyperthermia. PMID:17372629

  8. Bats avoid radar installations: could electromagnetic fields deter bats from colliding with wind turbines?

    PubMed

    Nicholls, Barry; Racey, Paul A

    2007-03-14

    Large numbers of bats are killed by collisions with wind turbines, and there is at present no direct method of reducing or preventing this mortality. We therefore determine whether the electromagnetic radiation associated with radar installations can elicit an aversive behavioural response in foraging bats. Four civil air traffic control (ATC) radar stations, three military ATC radars and three weather radars were selected, each surrounded by heterogeneous habitat. Three sampling points matched for habitat type and structure, dominant vegetation species, altitude and surrounding land class were located at increasing distances from each station. A portable electromagnetic field meter measured the field strength of the radar at three distances from the source: in close proximity (<200 m) with a high electromagnetic field (EMF) strength >2 volts/metre, an intermediate point within line of sight of the radar (200-400 m) and with an EMF strength <2 v/m, and a control site out of sight of the radar (>400 m) and registering an EMF of zero v/m. At each radar station bat activity was recorded three times with three independent sampling points monitored on each occasion, resulting in a total of 90 samples, 30 of which were obtained within each field strength category. At these sampling points, bat activity was recorded using an automatic bat recording station, operated from sunset to sunrise. Bat activity was significantly reduced in habitats exposed to an EMF strength of greater than 2 v/m when compared to matched sites registering EMF levels of zero. The reduction in bat activity was not significantly different at lower levels of EMF strength within 400 m of the radar. We predict that the reduction in bat activity within habitats exposed to electromagnetic radiation may be a result of thermal induction and an increased risk of hyperthermia.

  9. Modeling magnetospheric response to synthetic Alfvénic fluctuations in the solar wind: ULF wave fields in the magnetosphere

    NASA Astrophysics Data System (ADS)

    McGregor, S. L.; Hudson, M. K.; Hughes, W. J.

    2014-11-01

    Several observational studies suggest that small fluctuations in the solar wind can drive magnetospheric dynamics, notably ultralow frequency (ULF) waves, especially during high-speed streams (HSS). ULF fluctuations are believed to be a mechanism for controlling and accelerating radiation belt electrons, and are an important aspect to HSS storms. Previous simulation studies have begun to investigate generation of magnetospheric ULF waves by varying upstream solar wind conditions, such as dynamic pressure or velocity shear. Alfvénic fluctuations, however, which are prevalent within the solar wind, have yet to be incorporated into global MHD simulations of the magnetosphere. To investigate the relationship between Alfvénic fluctuations in the solar wind and magnetospheric ULF waves, we present results from the Lyon-Fedder-Mobarry global, three-dimensional magnetohydrodynamic (MHD) code. These simulations are driven with simulated solar wind plasma parameters from the Wang-Sheeley-Arge-Enlil model with and without Alfvén-like fluctuations added. We show that solar wind Alfvénic fluctuations enhance Kelvin-Helmholtz waves along the flanks and drive ULF waves in the dayside magnetosphere. The dayside ULF waves are an enhancement of the compressional component in field-aligned coordinates, due to the varying x component of the velocity (and therefore dynamic pressure) from the Alfvénic fluctuations.

  10. Comparison of aerosol backscatter and wind field estimates from the REAL and the SAMPLE

    NASA Astrophysics Data System (ADS)

    Mayor, Shane D.; Dérian, Pierre; Mauzey, Christopher F.; Spuler, Scott M.; Ponsardin, Patrick; Pruitt, Jeff; Ramsey, Darrell; Higdon, Noah S.

    2015-09-01

    Although operating at the same near-infrared 1.5- m wavelength, the Raman-shifted Eye-safe Aerosol Lidar (REAL) and the Scanning Aerosol Micro-Pulse Lidar-Eye-safe (SAMPLE) are very different in how they generate and detect laser radiation. We present results from an experiment where the REAL and the SAMPLE were operated side-by-side in Chico, California, in March of 2015. During the non-continuous, eleven day test period, the SAMPLE instrument was operated at maximum pulse repetition frequency (15 kHz) and integrated over the interpulse period of the REAL (0.1 s). Operation at the high pulse repetition frequency resulted in second trip echoes which contaminated portions of the data. The performance of the SAMPLE instrument varied with background brightness--as expected with a photon counting receiver|--yet showed equal or larger backscatter intensity signal to noise ratio throughout the intercomparison experiment. We show that a modest low-pass filter or smooth applied to the REAL raw waveforms (that have 5x higher range resolution) results in significant increases in raw signal-to-noise ratio and image signal-to-noise ratio--a measure of coherent aerosol feature content in the images resulting from the scans. Examples of wind fields and time series of wind estimates from both systems are presented. We conclude by reviewing the advantages and disadvantages of each system and sketch a plan for future research and development activities to optimize the design of future systems.

  11. Evolution of a localized Langmuir packet in the solar wind and on auroral field lines

    NASA Technical Reports Server (NTRS)

    Roth, I.; Muschietti, L.; Brown, E. F.; Gray, P. C.

    1994-01-01

    Langmuir emissions in space are reported to be clumpy and intermittent. The high-frequency wave power appears concentrated in spatial packets, whether amidst the solar wind or on auroral field lines. Due to the plasma motion relative to the spacecraft, determining the source for the wave free energy in the three-dimensional electron distribution function has always been difficult, since the unstable features pass by the detector in presumably too short time to be measured. The range of unstable phase velocities and growth rates have generally been estimated rather than determined by unequivocal measurements. The analysis of wave-particle interactions in a space environment has taken recently a new turn with the development of wave correlators on board rockets and satellites. Such instruments seek to identify correlations between the phase of the wave-field and the fluxes of energetic particles. The data interpretation is complex, however, it must be backed by a detailed theoretical understanding of the wave-particle interaction, including the phase relation for inhomogeneous packets. To this end Langmuir packets interacting with fast electrons can be studied in the appropriate regime by means of particle-in-cell simulations, provided that one succeeds in reducing the level of the fluctuations, enhancing the signal-to-noise ratio, and incorporating the appropriate boundary conditions. The first results of such simulations are presented here as a test and expansion of previous analysis.

  12. Applications of matched field processing to damage detection in composite wind turbine blades

    NASA Astrophysics Data System (ADS)

    Tippmann, Jeffery D.; Lanza di Scalea, Francesco

    2015-03-01

    There are many structures serving vital infrastructure, energy, and national security purposes. Inspecting the components and areas of the structure most prone to failure during maintenance operations by using non- destructive evaluation methods has been essential in avoiding costly, but preventable, catastrophic failures. In many cases, the inspections are performed by introducing acoustic, ultrasonic, or even thermographic waves into the structure and then evaluating the response. Sometimes the structure, or a component, is not accessible for active inspection methods. Because of this, there is a growing interest to use passive methods, such as using ambient noise, or sources of opportunity, to produce a passive impulse response function similar to the active approach. Several matched field processing techniques most notably used in oceanography and seismology applications are examined in more detail. While sparse array imaging in structures has been studied for years, all methods studied previously have used an active interrogation approach. Here, structural damage detection is studied by use of the reconstructed impulse response functions in ambient noise within sparse array imaging techniques, such as matched-field processing. This has been studied in experiments on a 9-m wind turbine blade.

  13. Sandia Wake Imaging System Field Test Report: 2015 Deployment at the Scaled Wind Farm Technology (SWiFT) Facility.

    SciTech Connect

    Naughton, Brian Thomas; Herges, Thomas

    2015-10-01

    This report presents the objectives, configuration, procedures, reporting , roles , and responsibilities and subsequent results for the field demonstration of the Sandia Wake Imaging System (SWIS) at the Sandia Scaled Wind Farm Technology (SWiFT) facility near Lubbock, Texas in June and July 2015.

  14. THEMIS/ARTEMIS Observations of Kinetic-Scale Turbulence in the Solar Wind: Analysis of Electric and Magnetic Field Fluctuations

    NASA Astrophysics Data System (ADS)

    Hanson, E.; Salem, C. S.; Bonnell, J. W.; Chaston, C. C.; Bale, S. D.; Mozer, F.

    2015-12-01

    We present here an analysis of kinetic-scale electromagnetic fluctuations in the solar wind using data from THEMIS and ARTEMIS spacecraft. We use high-time resolution electric and magnetic field measurements, as well as density fluctuations, up to 128 samples per second, as well as particle burst plasma data during carefully selected solar wind intervals. We focus our analysis on 8-10 such intervals spanning different values of plasma beta and angles between the local magnetic field and the radial Sun-Earth direction. We discuss the careful analysis process of characterizing and removing the different instrumental effects and noise sources affecting the electric and magnetic field data at those scales, above 0.1 Hz or so, above the breakpoint marking the start of the so-called dissipation range of solar wind turbulence. We compute parameters such as the electric to magnetic field ratio, the magnetic compressibility, magnetic helicity, and other relevant quantities in order to diagnose the nature of the fluctuations at those scales between the ion and electron cyclotron frequencies, extracting information on the dominant modes composing the fluctuations. We also discuss the presence and role of coherent structures in the measured fluctuations. The nature of the fluctuations in the dissipation or dispersive scales of solar wind turbulence is still debated. This observational study is also highly relevant to the current Turbulent Dissipation Challenge.

  15. Does the magnetic field of a multipole stator winding drive flow of a ferrofluid in a cylindrical container?

    NASA Astrophysics Data System (ADS)

    Torres-Díaz, Isaac; Rinaldi, Carlos

    The flow of a ferrofluid in a stationary cylindrical container driven by a rotating magnetic field has received considerable attention since the inception of the field of ferrohydrodynamics. Much controversy has resulted regarding the existence, or lack thereof, of bulk flow under conditions of a rotating uniform magnetic field, which can be generated for example, using a two-pole stator winding. The original observations of flow at the interface showed counter-rotation of field and fluid, whereas recent observations of bulk flow using the ultrasound technique have shown co-rotation of field and fluid. Various theories have been advanced over the years to explain the observed phenomena, including the spin diffusion theory of Shliomis and the hypothesis that it is field non-uniformity, generated by non-ideal stator winding distributions, that actually drives the flow, as first proposed by Glazov. We have revisited this problem from an analytical perspective by solving the ferrohydrodynamic and magnetoquasistatic equations self-consistently for the case of ferrofluid in a cylindrical container, with and without an internal co-axial cylinder, and driven by the field generated by a multipole stator winding distribution. In such a winding increasing the number of poles results in increasingly non-uniform fields. It is shown that regardless of the number of poles in the stator winding the ferrohydrodynamic equations do not predict any flow in either geometry as long as the spin viscosity parameter is assumed to be zero. Velocity profiles are obtained for both geometries and arbitrary number of poles for the case of non-zero spin viscosity. It is shown that only for the case of a two-pole stator winding and ferrofluid constrained to the annular space between an inner and outer cylinder do the ferrohydrodynamic equations predict co-rotation of fluid and field close to the outer cylinder and counter-rotation of fluid and field close to the inner cylinder, in qualitative

  16. Ageostrophic winds and vertical motion fields accompanying upper level jet streak propagation during the Red River Valley tornado outbreak

    NASA Technical Reports Server (NTRS)

    Moore, J. T.; Squires, M. F.

    1982-01-01

    Preliminary results are shown relating the ageostrophic wind field, through the terms of a semigeostrophic wind equation (assuming adiabatic conditions and the geostrophic momentum approximation) to both air parcel trajectories and their vertical motion fields computed from the parcels' displacement on isentropic surfaces, with respect to pressure. The analysis of results considers both upper-level (324 K) ageostrophic fields and low-level (304 K) fields. Preliminary results tend to support Uccellini and Johnson's (1979) hypothesis concerning upper-level-jet/low-level-jet (ULJ/LLJ) coupling in the exit region of the ULJ. Future plans are described briefly for research intended to clarify the mechanism behind ULJ streak propagation, LLJ development and their relationship to the initiation of severe convection.

  17. Waves in the magnetic field and solar wind flow outside the bow shock at comet P/Halley

    NASA Technical Reports Server (NTRS)

    Johnstone, A.; Glassmeier, K.; Acuna, M.; Borg, H.; Bryant, D.

    1987-01-01

    The existence of hydromagnetic waves in the mass-loaded solar wind upstream from the bow shock of a comet is well-established both for comet Giacobini-Zinner and for comet Halley. Whereas previous reports have been concerned either with the magnetic field observations or with plasma observations, here observations of the magnetic field with the solar wind proton and alpha particle distributions are combined. This allows the three possible modes of propagation for these waves to be separated. The magnetic component is predominantly transverse to the magnetic field and linearly polarized. The flow vector also has a substantial amount of power parallel to the magnetic field. An examination of the pressure variations shows that slow magnetosonic waves are more common than the fast mode.

  18. Surface wind, pressure and temperature fields near tornadic and non-tornadic narrow cold-frontal rainbands

    NASA Astrophysics Data System (ADS)

    Clark, Matthew; Parker, Douglas

    2014-05-01

    Narrow cold frontal rainbands (NCFRs) occur frequently in the UK and other parts of northwest Europe. At the surface, the passage of an NCFR is often marked by a sharp wind veer, abrupt pressure increase and a rapid temperature decrease. Tornadoes and other instances of localised wind damage sometimes occur in association with meso-gamma-scale vortices (sometimes called misocyclones) that form along the zone of abrupt horizontal wind veer (and associated vertical vorticity) at the leading edge of the NCFR. Using one-minute-resolution data from a mesoscale network of automatic weather stations, surface pressure, wind and temperature fields in the vicinity of 12 NCFRs (five of which were tornadic) have been investigated. High-resolution surface analyses were obtained by mapping temporal variations in the observed parameters to equivalent spatial variations, using a system velocity determined by analysis of the radar-observed movement of NCFR precipitation segments. Substantial differences were found in the structure of surface wind and pressure fields close to tornadic and non-tornadic NCFRs. Tornadic NCFRs exhibited a large wind veer (near 90°) and strong pre- and post-frontal winds. These attributes were associated with large vertical vorticity and horizontal convergence across the front. Tornadoes typically occurred where vertical vorticity and horizontal convergence were increasing. Here, we present surface analyses from selected cases, and draw comparisons between the tornadic and non-tornadic NCFRs. Some Doppler radar observations will be presented, illustrating the development of misocyclones along parts of the NCFR that exhibit strong, and increasing, vertical vorticity stretching. The influence of the stability of the pre-frontal air on the likelihood of tornadoes will also be discussed.

  19. Field-Aligned Current Dynamics and Its Correlation with Solar Wind Conditions and Geomagnetic Activities From Space Technology 5 Observations

    NASA Astrophysics Data System (ADS)

    Wang, Yongli; Boardsen, Scott; Le, Guan; Slavin, James; Strangeway, Robert J.

    Field-aligned currents (FACs) are the currents flowing into and out of the ionosphere which connect to the magnetosphere. They provide an essential linkage between the solar wind - magnetosphere system and the ionosphere, and the understanding of these currents is important for global magnetosphere dynamics and space weather prediction. The three spacecraft ST-5 constellation provides an unprecedented opportunity to study in situ FAC dynamics in time scales (10 sec to 10 min) that can not be achieved previously with single spacecraft studies or large-spaced conjugate spacecraft studies. In this study, we use the magnetic field observations during the whole ST-5 mission to study the dependence of FAC current sheet motion and intensity on solar wind conditions. FAC peak current densities show very good correlations with some solar wind parameters, including IMF Bz, dynamic pressure, Ey, and some IMF angles, but not with other parameters. Instant FAC speeds show generally much weaker dependence on solar wind conditions comparing to FAC peak current densities. This obvious uncorrelation between FAC peak current densities and speeds implies that FAC peak current densities are more consistently controlled by solar wind conditions and geomagnetic activities, while FAC speeds are more oscillatory, sometimes with higher speeds during quieter times and lower speeds during more turbulent times. Detailed examination of FAC current sheet speed during two major storms in the ST-5 mission will also be given to illustrate the temporal evolution of the FAC dynamics with geomagnetic storm.

  20. Two-dimensional inflow-wind solution of black hole accretion with an evenly symmetric magnetic field

    NASA Astrophysics Data System (ADS)

    Mosallanezhad, Amin; Bu, Defu; Yuan, Feng

    2016-03-01

    We solve the two-dimensional magnetohydrodynamic (MHD) equations of black hole accretion with the presence of magnetic field. The field includes a turbulent component, whose role is represented by the viscosity, and a large-scale ordered component. The latter is further assumed to be evenly symmetric with the equatorial plane. The equations are solved in the r - θ plane of a spherical coordinate by assuming time-steady and radially self-similar. An inflow-wind solution is found. Around the equatorial plane, the gas is inflowing; while above and below the equatorial plane at a certain critical θ angle, θ ˜ 47°, the inflow changes its direction of radial motion and becomes wind. The driving forces are analysed and found to be the centrifugal force and the gradient of gas and magnetic pressure. The properties of wind are also calculated. The specific angular momentum of wind is found to be significantly larger than that of inflow, thus wind can transfer angular momentum outward. These analytical results are compared to those obtained by the trajectory analysis based on MHD numerical simulation data and good agreements are found.

  1. Application of a Solar Wind Model Driven by Turbulence Dissipation to a 2D Magnetic Field Configuration

    NASA Astrophysics Data System (ADS)

    Lionello, Roberto; Velli, Marco; Downs, Cooper; Linker, Jon A.; Mikić, Zoran

    2014-12-01

    Although it is widely accepted that photospheric motions provide the energy source and that the magnetic field must play a key role in the process, the detailed mechanisms responsible for heating the Sun's corona and accelerating the solar wind are still not fully understood. Cranmer et al. developed a sophisticated, one-dimensional (1D), time-steady model of the solar wind with turbulence dissipation. By varying the coronal magnetic field, they obtain, for a single choice of wave properties, a realistic range of slow and fast wind conditions with a sharp latitudinal transition between the two streams. Using a 1D, time-dependent model of the solar wind of Lionello et al., which incorporates turbulent dissipation of Alfvén waves to provide heating and acceleration of the plasma, we have explored a similar configuration, obtaining qualitatively equivalent results. However, our calculations suggest that the rapid transition between slow and fast wind suggested by this 1D model may be disrupted in multidimensional MHD simulations by the requirement of transverse force balance.

  2. Application of a solar wind model driven by turbulence dissipation to a 2D magnetic field configuration

    SciTech Connect

    Lionello, Roberto; Downs, Cooper; Linker, Jon A.; Mikić, Zoran; Velli, Marco E-mail: cdowns@predsci.com E-mail: mikic@predsci.com

    2014-12-01

    Although it is widely accepted that photospheric motions provide the energy source and that the magnetic field must play a key role in the process, the detailed mechanisms responsible for heating the Sun's corona and accelerating the solar wind are still not fully understood. Cranmer et al. developed a sophisticated, one-dimensional (1D), time-steady model of the solar wind with turbulence dissipation. By varying the coronal magnetic field, they obtain, for a single choice of wave properties, a realistic range of slow and fast wind conditions with a sharp latitudinal transition between the two streams. Using a 1D, time-dependent model of the solar wind of Lionello et al., which incorporates turbulent dissipation of Alfvén waves to provide heating and acceleration of the plasma, we have explored a similar configuration, obtaining qualitatively equivalent results. However, our calculations suggest that the rapid transition between slow and fast wind suggested by this 1D model may be disrupted in multidimensional MHD simulations by the requirement of transverse force balance.

  3. Chemical and microbiological parameters in New Orleans floodwater following Hurricane Katrina.

    PubMed

    Pardue, J H; Moe, W M; McInnis, D; Thibodeaux, L J; Valsaraj, K T; Maciasz, E; van Heerden, I; Korevec, N; Yuan, Q Z

    2005-11-15

    Hurricane Katrina, rated as a Category 4 hurricane on the Saffir-Simpson scale, made landfall on the U.S. Gulf Coast near New Orleans, Louisiana on Monday, August 29, 2005. The storm brought heavy winds and rain to the city, and several levees intended to protect New Orleans from the water of Lake Pontchartrain were breached. Consequently, up to 80% of the city was flooded with water reaching depths in excess of three meters in some locations. Research described in this paper was conducted to provide an initial assessment of contaminants present in floodwaters shortly after the storm and to characterize water pumped out of the city into Lake Pontchartrain once dewatering operations began several days after the storm. Data are presented which demonstrate that during the weeks following the storm, floodwater was brackish and well-buffered with very low concentrations of volatile and semivolatile organic pollutants. Dissolved oxygen was depleted in surface floodwater, averaging 1.6 mg/L in the Lakeview district and 4.8 mg/L in the Mid-City district. Dissolved oxygen was absent (< 0.02 mg/L) at the bottom of the floodwater column in the Mid-City district 9 days afterthe storm. Chemical oxygen demand (Mid-City average = 79.9 mg/L) and fecal coliform bacteria (Mid-City average = 1.4 x 10(5) MPN/100 mL) were elevated in surface floodwater but typical of stormwater runoff in the region. Lead, arsenic, and in some cases, chromium, exceeded drinking water standards but with the exception of some elevated Pb concentrations generally were typical of stormwater. Data suggest that what distinguishes Hurricane Katrina floodwater is the large volume and the human exposure to these pollutants that accompanied the flood, rather than very elevated concentrations of toxic pollutants. PMID:16323752

  4. Wind-wave coupling in the atmospheric boundary layer over a reservoir: field measurements and verification of the model

    NASA Astrophysics Data System (ADS)

    Troitskaya, Yuliya; Papko, Vladislav; Baidakov, Georgy; Vdovin, Maxim; Kandaurov, Alexander; Sergeev, Daniil

    2013-04-01

    This paper presents the results of field experiments conducted at the Gorky Reservoir to test a quasi-linear model of the atmospheric boundary layer [1]. In the course of the experiment we simultaneously measured profiles of wind speed and surface wave spectra using instruments placed on the Froude buoy, which measures the following parameters: i) the module and the direction of the wind speed using ultrasonic wind sensor WindSonic Gill instruments, located on the 4 - levels from 0.1 x 5 m long; ii) profile of the surface waves with 3-channel string wave-gauge with a base of 5 cm, iii) the temperature of the water and air with a resistive sensor. From the measured profiles of wind speed, we calculated basic parameters of the atmospheric boundary layer: the friction velocity u*, the wind speed at the standard height of 10 m U10 and the drag coefficient CD. Data on CD(U10), obtained at the Gorky Reservoir, were compared with similar data obtained on Lake George in Australia during the Australian Shallow Water Experiment (AUSWEX) conducted in 1997 - 1999 [2,3]. A good agreement was obtained between measured data at two different on the parameters of inland waters: deep Gorky reservoir and shallow Lake George.To elucidate the reasons for this coincidence of the drag coefficients under strongly different conditions an analysis of surface waves was conducted.Measurements have shown that in both water bodies the surface wave spectra have almost the same asymptotics (spatial spectrum - k-3, the frequency spectrum -5), corresponding to the Phillips saturation spectrum.These spectra are typically observed for the steep surface waves, for which the basic dissipation mechanism is wave breaking. The similarity of the short-wave parts of the spectra can be regarded as a probable cause of coincidence of dependency of drag coefficient of the water surface on wind speed. Quantitative verification of this hypothesis was carried out in the framework of quasi-linear model of the wind

  5. Anisotropies of the Taylor Scale, Correlation Scale, and Effective Magnetic Reynolds Number Determination from Solar Wind Magnetic Field Fluctuations

    NASA Astrophysics Data System (ADS)

    Weygand, J. M.; Kivelson, M. G.; Matthaeus, M. H.; Dasso, S.; Kistler, L. M.

    2009-04-01

    ACE, Cluster, Geotail, IMP-8, Interball, THEMIS, and Wind data from many different intervals in the solar wind are employed to determine the magnetic correlation scale and the Taylor microscale from simultaneous multiple point measurements. For this study we define the correlation scale as the exponential decay constant of the correlation coefficient as a function of spacecraft separation and the Taylor scale as the radius of curvature of the correlation coefficient values at zero separation. The present determination of the Taylor scale makes use of a novel extrapolation technique to derive a statistically stable estimate from a range of measurements at small spatial separations [Weygand et al., 2007]. Using all the slow solar wind data (600 km/s), the correlation scale length is found to be smallest (about 1.3x106 km) in the direction parallel to the magnetic field and largest (about 2.2x106 km) in the direction perpendicular to the magnetic field. The anisotropies in the turbulent magnetic fluctuations in the solar wind are consistent with slow solar containing mainly two-dimensional turbulence and the fast solar wind having mostly slab type turbulence. The effective magnetic Reynolds number can be expressed in terms of the correlation scale and the Taylor scale. The difference in the Taylor and correlation scale in the parallel and perpendicular direction indicates that the effective magnetic Reynolds number varies with the direction of the magnetic field and has values between 1x106 and 8x106 . Knowledge of the effective magnetic Reynolds number may be useful in magnetohydrodynamic modeling of the solar wind and galactic cosmic ray diffusion in the heliosphere.

  6. Modeling the connection of the global ionospheric electric fields to the solar wind

    NASA Astrophysics Data System (ADS)

    Rothwell, P. L.; Jasperse, J. R.

    2006-03-01

    A global ionospheric electrostatic potential model, which we refer to as Nopper-Carovillano (N-C), can be linked with a magnetospheric potential model. The latter model, which we refer to as Hill-Siscoe-Ober (H-S-O), computes a transpolar potential ΦPC(H-S-O) based on solar wind parameters and region-1 field-aligned currents (FAC) from the magnetosheath to the ionosphere. The polar ionospheric conductance required by H-S-O is defined by the N-C model. In this way, the transpolar potential and the associated FAC are the same in both models. A distribution of region-1 FAC in the N-C model predicts a two-cell convection pattern which is in reasonable agreement with plasma drifts measured by DMSP (Defense Meteorological Satellite Program) satellites. The H-S-O model, as modified by N-C, is compared with the Weimer potential model and with the transpolar potentials observed by DMSP satellites during the 6-7 April 2000 magnetic storm. Good agreement is found in both cases. The region-2 (J2) current is estimated from the Siscoe (S-RC) ring-current circuit model which is driven by ΦPC(H-S-O). The resistor values in S-RC, as determined by N-C, when combined with the global potential solution, make it possible to estimate the time profile of the equatorial penetration electric field during the storm's main phase. With the values obtained, shielding occurs within 1 hour of onset. Equatorial plasma bubbles (EPBs) are seen some hours after the initial increase of ΦPC and are qualitatively consistent with the equatorial penetration electric field calculated by the combined model.

  7. Anisotropy of the Taylor scale and the correlation scale in plasma sheet and solar wind magnetic field fluctuations

    NASA Astrophysics Data System (ADS)

    Weygand, James M.; Matthaeus, W. H.; Dasso, S.; Kivelson, M. G.; Kistler, L. M.; Mouikis, C.

    2009-07-01

    Magnetic field data from nine spacecraft in the magnetospheric plasma sheet and the solar wind are employed to determine the correlation scale and the magnetic Taylor microscale from simultaneous multiple-point measurements for multiple intervals with a range of mean magnetic field directions. We have determined that in the solar wind the Taylor scale is independent of direction relative to the mean magnetic field, but the correlation scale along the mean magnetic field (2.7 × 106 ± 0.2 × 106 km) is longer than along the perpendicular direction (1.5 × 106 ± 0.1 × 106 km). Within the plasma sheet we found that the correlation scale varies from 16,400 ± 1000 km along the mean magnetic field direction to 9200 ± 600 km in the perpendicular direction. The Taylor scale is also longer parallel to the magnetic field (2900 ± 100 km) than perpendicular to it (1100 ± 100 km). In the solar wind the ratio of the parallel correlation scale to the perpendicular correlation scale is 2.62 ± 0.79; in the plasma sheet the ratio is 1.78 ± 0.16, which indicates that the turbulence in both regions is anisotropic. The correlation and Taylor scales may be used to estimate effective magnetic Reynolds numbers separately for each angular channel. Reynolds numbers were found to be approximately independent of the angle relative to the mean magnetic field. These results may be useful in magnetohydrodynamic modeling of the solar wind and the magnetosphere and can contribute to our understanding of solar and galactic cosmic ray diffusion in the heliosphere.

  8. A case and statistical study of transient magnetic field events at geosynchronous orbit and their solar wind origin

    NASA Technical Reports Server (NTRS)

    Borodkova, N. L.; Zastenker, G. N.; Sibeck, D. G.

    1995-01-01

    We present a statisical survey of Prognoz 10 solar wind observations at the times of transient (step function and impulsive) variations in the dayside magnetospheric magnetic field strength measured by the GOES 5 and 6 geosynchronous satellites. The results indicate that 51% of the magnetospheric events can be associated with corresponding variations in the solar wind dynamic pressure. A further 17% of the events can be associated with fluctuations in the interplanetary magnetic field orientation in the sense previously associated with foreshock pressure pulses. We find no tendency for impulsive events at dayside geosynchronous orbit to be associated with north/south fluctuations in the interplanetary magnetic field (IMF) orientation, nor for the events to occur primarily during intervals of southward IMF. The success rate for associating transient events at dayside geosynchronous orbit with solar wind features decreases as Prognoz 10 moves farther from the Earth-Sun line. The observations indicate that variations in the solar wind dynamic pressure and foreshock pressure pulses associated with variations in the IMF cone angle are the predominant causes of large-amplitude transient events observed at dayside geosynchronous orbit.

  9. On the role of the magnetic field in the solar wind interaction with Venus - Expectations versus observations

    NASA Technical Reports Server (NTRS)

    Luhmann, J. G.; Elphic, R. C.; Russell, C. T.; Brace, L.

    1981-01-01

    Observations of the magnetic field near Venus suggest that elements of three different models (direct interaction, tangential discontinuity, magnetic barrier) are present. A bow shock is found to occur at an altitude of about 0.3 Venus radii at the subsolar point. The compression of the decelerated solar wind plasma behind the bow shock causes interplanetary field lines to 'pile up'. The magnetic field inside the bow shock increases from approximately twice the IMF strength at the bow shock to values in the range of approximately 40-100 gammas at altitudes between about 200 and 1,200 km. The maximum value of the piled up field, which is correlated with the dynamic pressure of the solar wind outside the bow shock, is found at lower altitudes for larger field strengths. Just Venus-ward of the maximum field, the pressure of the cold plasma increases to a level balancing the pressure of the external magnetic field. Hence, to a first approximation, the ionosphere has a diamagnetic response excluding the magnetosheath field. However, strong magnetic fields are found at times throughout the ionosphere.

  10. Multi-scale Anti-correlation Between Electron Density and Magnetic Field Strength in the Solar Wind

    NASA Astrophysics Data System (ADS)

    Yao, Shuo; He, J.-S.; Marsch, E.; Tu, C.-Y.; Pedersen, A.; Rème, H.; Trotignon, J. G.

    2011-02-01

    This work focuses on the relation between the electron density and the magnetic field strength in the solar wind, and aims to reveal its compressive nature and to determine the level of compressibility. For this purpose, we choose a period of quiet solar wind data obtained at 1 AU by the Cluster C1 satellite. The electron density is derived with a sampling time as high as 0.2 s from the spacecraft-potential measurements made by the Electric Field and Waves instrument. We use the wavelet cross-coherence method to analyze the correlation between the electron density and the magnetic field strength on various scales. We find a dominant anti-correlation between them at different timescales ranging from 1000 s down to 10 s, a result which has never been reported before. This may indicate the existence of pressure-balanced structures (PBSs) with different sizes in the solar wind. The small (mini) PBSs appear to be embedded in the large PBSs, without affecting the pressure balance between the large structures. Thus, a nesting of these possible multi-scale PBSs is found. Moreover, we find for the first time that the relative fluctuation spectra of both the electron number density and the magnetic field strength look almost the same in the range from 0.01 Hz to 2.5 Hz, implying a similar cascading for these two types of fluctuations. Probable formation mechanisms for the multi-scale possible PBSs are discussed. The results of our work are believed to be helpful for understanding the compressive nature of solar wind turbulence as well as the connections between the solar wind streams and their coronal sources.

  11. Comparison of PI-SWERL with dust emission measurements from a straight-line field wind tunnel

    NASA Astrophysics Data System (ADS)

    Sweeney, Mark; Etyemezian, Vic; MacPherson, Torin; Nickling, William; Gillies, John; Nikolich, George; McDonald, Eric

    2008-03-01

    The Portable In situ Wind ERosion Lab (PI-SWERL) was developed to measure dust emissions from soil surfaces. This small, portable unit can test the emissivity of soils in areas that are difficult to access with a field wind tunnel, and can complete a larger number of tests in less time. The PI-SWERL consists of a cylindrical enclosure containing an annular flat blade that rotates at different speeds, which generates shear stress upon the surface. The shear stress generated by PI-SWERL results in the entrainment of particles including dust. PI-SWERL was developed to provide an index of dust emission potential comparable to the field wind tunnel. The PI-SWERL dust emission results were compared against those obtained from a ˜12 m long, 1 m wide, 0.75 m high straight line suction-type portable field wind tunnel by conducting collocated tests at 32 distinct field settings and soil conditions in the Mojave Desert of southern California. Clay- to sand-rich soils that displayed a range of crusting, gravel cover, and disturbance were tested. The correspondence between dust emissions (mg m-2 s-1) for the two instruments is nearly 1:1 on most surfaces. Deviation between the two instruments was noted for densely packed gravel surfaces. For rough surfaces a correction can be applied to the PI-SWERL that results in comparable dust emission data to the wind tunnel. PI-SWERL can be used to complement research efforts in aeolian geomorphology aimed to quantify spatial and temporal patterns of dust emissions as well as air quality research related to dust emissions.

  12. Solar Wind Magnetic Field Turbulence at Ion Kinetic Scales Measured by Cluster Using k-filtering Technique

    NASA Astrophysics Data System (ADS)

    Li, X.; Roberts, O. W.; Jeska, L.; Li, B.; Lu, Q.

    2014-12-01

    The nature of turbulence at kinetic scales is important since turbulence energy is believed to dissipate as heat at these scales. Here we report our several work on the solar wind turbulence at ion kinetic scales using the k-filtering technique. We found evidence of ion cyclotron resonance in solar wind intervals. In the wave vector space, in addition to the commonly observed population of magnetic field fluctuations propagating at quasi-perpendicular angles to the global mean field B0, a population propagating at quasi-parallel angles are also observed with no local plasma instabilities identified. At low wavenumbers (kv_A/Omega_p <= 0.6 ) both components are present, and have similar powers, while at higher wavenumbers (kv_A/Omega_p> 0.6) only the perpendicular component can be identified. A statistical study of 52 intervals of solar wind finds that the turbulence is predominantly highly oblique to the magnetic field with perpendicular wavenumbers much greater than parallel wavenumbers, and propagates slowly in the plasma frame with most points having frequencies smaller than the proton gyrofrequency. Weak agreement is found that turbulence at the ion kinetic scales consists of kinetic Alfven waves and coherent structures advected with plasma bulk velocity plus some minor more compressible components. The results suggest that anti-sunward and sunward propagating magnetic fluctuations have similar nature in both the fast and slow solar wind. The fast wind was shown to have significantly more anti-sunward flux than sunward flux and the slow wind appears to be more balanced at ion kinetic scales. The fluctuated magnetic field and magnitude of the magnetic field are used to compute the power of incompressible and compressible turbulence for the fast solar wind. It is found that Taylor's frozen-in hypothesis may break down for compressible turbulence at the ion kinetic scales, suggesting that whistler waves may contribute to the compressible turbulence on the scales

  13. Stable motions of charged dust grains subject to solar wind, Poynting-Robertson drag, and the mean interplanetary magnetic field

    NASA Astrophysics Data System (ADS)

    Lhotka, Christoph; Bourdin, Philippe; Narita, Yasuhito

    2016-10-01

    We investigate the combined effect of solar wind, Poynting-Robertson drag, and the frozen-in interplanetary magnetic field on the motion of charged dust grains in our solar system. It is generally accepted that the combined effects of solar wind and photon absorption and re-emmision (Poynting-Robertson drag) lead to a decrease in semi-major axis on secular time scales. On the contrary, we demonstrate that the interplanetary magnetic field may counteract these drag forces under certain circumstances. We derive a simple relation between the parameters of the magnetic field, the physical properties of the dust grain as well as the shape and orientation of the orbital ellipse of the particle, which is a necessary conditions for the stabilization in semi-major axis.

  14. Examination of ionic wind and cathode sheath effects in a E-field premixed flame with ion density measurements

    NASA Astrophysics Data System (ADS)

    Jacobs, Stewart V.; Xu, Kunning G.

    2016-04-01

    The effect of the ionic wind on a premixed methane-air flame under a DC electric field is studied via mapping of the ion density with Langmuir probes. Ion densities were observed to increase near the burner with increasing electrode voltage up to 6 kV. Past this electrode supply voltage, ion densities ceased increasing and began to decline in some locations within the premixed flame. The increased ion density is caused by an increase in ionic wind force and cathode sheath thickness. The plateau in density is due to the cathode sheath fully encompassing the flame front which is the ion source, thereby collecting all ions in the flame. The spatial density data support the ionic wind hypothesis and provide further explanation of its limits based on the plasma sheath.

  15. Solar Wind Activity Dependence of the Occurrence of Field-Line Resonance at low Latitudes (L~1.3)

    NASA Astrophysics Data System (ADS)

    Takasaki, S.; Kawano, H.; Tanaka, Y.; Yoshikawa, A.; Seto, M.; Iijima, M.; Yumoto, K.

    2002-12-01

    It is known that the field line resonance (FLR below) is caused by hydromagnetic waves in the magnetosphere. The fundamental field line eigenfrequency can be expressed by the magnetic field line length, the magnetic field intensity, and the plasma density at the magnetic field line. We can measure the fundamental field line eigenfrequency by ground-based observation. The field line length and the magnetic field intensity can be calculated from some magnetic field model (such as the IGRF model) of the magnetosphere. Then, it is possible that the plasma density at the magnetic field line is determined by these factors. The final aim of this study is to monitor and study time-dependent changes in the plasmaspheric plasma distributions by using ground magnetic field observations. For this purpose, we are working in the following three research phases. The first phase is to confirm the possibility of identifying FLR at low-latitudes (L~1.3). The second phase is to examine the correlation between FLR and solar wind parameters. The third phase is to estimate the plasma density from the FLR data, and monitor the density in a continuous manner. We are now in the third phase, and we report here the results of the first two phase. In the first phase, in order to investigate features of FLR close to the Earth, we installed three magnetometers in Japan at L~1.3 (at Kawatabi, Zaou, and Iitate), and started observing ULF geomagnetic pulsations. Each adjacent stations are separated in latitude by 50 to 100 km. The magnetic field data from these stations and Kakioka geomagnetic observatory, Japan, were analyzed by using the amplitude-ratio method and the cross-phase method. As a result, we identified FLR events whose frequency decreased with decreasing geomagnetic latitude; we infer that this feature was caused by heavy ion mass loading to low-L field lines. In the second phase, we studied the dependence of the occurrence probability of the above-identified FLR events on solar wind

  16. Parametric study of the solar wind interaction with the Hermean magnetosphere for a weak interplanetary magnetic field

    NASA Astrophysics Data System (ADS)

    Varela, J.; Pantellini, F.; Moncuquet, M.

    2016-01-01

    The aim of this study is to simulate the interaction of the solar wind with the Hermean magnetosphere when the interplanetary magnetic field is weak, performing a parametric study for all the range of hydrodynamic values of the solar wind predicted on Mercury for the ENLIL + GONG WSA + Cone SWRC model: density from 12 to 180 cm-3, velocity from 200 to 500 km/s and temperatures from 2 ·104 to 18 ·104 K, and compare the results with a real MESSENGER orbit as reference case. We use the code PLUTO in spherical coordinates and an asymmetric multipolar expansion for the Hermean magnetic field. The study shows for all simulations a stand off distance larger than the Mercury radius and the presence of close magnetic field lines on the day side of the planet, so the dynamic pressure of the solar wind is not high enough to push the magnetopause on the planet surface if the interplanetary magnetic field is weak. The simulations with large dynamic pressure lead to a large compression of the Hermean magnetic field modifying its topology in the inner magnetosphere as well as the plasma flows from the magnetosheath towards the planet surface.

  17. An evidence for prompt electric field disturbance driven by changes in the solar wind density under northward IMF Bz condition

    NASA Astrophysics Data System (ADS)

    Rout, Diptiranjan; Chakrabarty, D.; Sekar, R.; Reeves, G. D.; Ruohoniemi, J. M.; Pant, Tarun K.; Veenadhari, B.; Shiokawa, K.

    2016-05-01

    Before the onset of a geomagnetic storm on 22 January 2012 (Ap = 24), an enhancement in solar wind number density from 10/cm3 to 22/cm3 during 0440-0510 UT under northward interplanetary magnetic field (IMF Bz) condition is shown to have enhanced the high-latitude ionospheric convection and also caused variations in the geomagnetic field globally. Conspicuous changes in ΔX are observed not only at longitudinally separated low-latitude stations over Indian (prenoon), South American (midnight), Japanese (afternoon), Pacific (afternoon) and African (morning) sectors but also at latitudinally separated stations located over high and middle latitudes. The latitudinal variation of the amplitude of the ΔX during 0440-0510 UT is shown to be consistent with the characteristics of prompt penetration electric field disturbances. Most importantly, the density pulse event caused enhancements in the equatorial electrojet strength and the peak height of the F layer (hmF2) over the Indian dip equatorial sector. Further, the concomitant enhancements in electrojet current and F layer movement over the dip equator observed during this space weather event suggest a common driver of prompt electric field disturbance at this time. Such simultaneous variations are found to be absent during magnetically quiet days. In absence of significant change in solar wind velocity and magnetospheric substorm activity, these observations point toward perceptible prompt electric field disturbance over the dip equator driven by the overcompression of the magnetosphere by solar wind density enhancement.

  18. Multi-parameter Correlation of Jovian Radio Emissions with Solar Wind and Interplanetary Magnetic Field Data

    NASA Astrophysics Data System (ADS)

    MacDowall, R. J.; Golla, T.; Reiner, M. J.; Farrell, W. M.

    2015-12-01

    Variability of the numerous varieties of Jovian radio emission has been associated with aspects of solar wind (SW) and interplanetary magnetic field (IMF) parameters outside the magnetosphere. Here we demonstrate multiple-parameter correlations that relate each of several Jovian emissions, including bKOM and quasi-periodic bursts, to the SW and IMF impacting the Jovian magnetosphere. The data used are from the Ulysses spacecraft with radio data from the Unified Radio and Plasma wave (URAP) instrument, which provides high-quality remote radio observations of the Jovian emissions. The URAP observations are correlated with SW and IMF data from the relevant instruments on Ulysses, propagated to the nose of the Jovian magnetosphere with a sophisticated code. Because the aphelion of the Ulysses orbit was at the Jovian distance from the Sun, Ulysses spent ample time near Jupiter in 1991-1992 and 2003-2004, which are the intervals analyzed. Our results can be inverted such that radio observations by a Jovian orbiter, such as Cassini or Juno, are able to identify SW/IMF changes based on the behavior of the radio emissions.

  19. Modeling cross-field transport of solar energetic particles including solar wind effects

    NASA Astrophysics Data System (ADS)

    Lampa, Florian; Kallenrode, May-Britt

    Under consideration of solar wind effects, we have extended the Ruffolo's equation of focused transport for solar energetic particles to accommodate perpendicular transport in the ecliptic plane, and made a different approach concerning the reference frame. Numerically, the additional transport term is solved with the implicit and stable Laasonen scheme. In parameter studies and fits to observations for typical ratios κ⊥ /κ ranging between 0.02 and 0.1 at 1 AU as suggested in numerous studies (e.g. non-linear guiding-center theory) and a scaling of κ⊥ with r2 as suggested from the random walk of field lines as well as from numerical simulations, we find that azimuthal spread as well as the variation of maximum intensities with longitude is comparable to the ones inferred from multi-spacecraft observations. Implications for the interpretation of the observed intensity and anisotropy time profiles and consequences for our understanding of particle propagation and acceleration in space will be discussed.

  20. Singular-Arc Time-Optimal Trajectory of Aircraft in Two-Dimensional Wind Field

    NASA Technical Reports Server (NTRS)

    Nguyen, Nhan

    2006-01-01

    This paper presents a study of a minimum time-to-climb trajectory analysis for aircraft flying in a two-dimensional altitude dependent wind field. The time optimal control problem possesses a singular control structure when the lift coefficient is taken as a control variable. A singular arc analysis is performed to obtain an optimal control solution on the singular arc. Using a time-scale separation with the flight path angle treated as a fast state, the dimensionality of the optimal control solution is reduced by eliminating the lift coefficient control. A further singular arc analysis is used to decompose the original optimal control solution into the flight path angle solution and a trajectory solution as a function of the airspeed and altitude. The optimal control solutions for the initial and final climb segments are computed using a shooting method with known starting values on the singular arc The numerical results of the shooting method show that the optimal flight path angle on the initial and final climb segments are constant. The analytical approach provides a rapid means for analyzing a time optimal trajectory for aircraft performance.

  1. Scaling from Field to Region for Wind Erosion prediction Using WEPS and GIS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Wind Erosion Prediction System (WEPS) simulates soil erosion and dust emissions from agricultural soils. Due to the severe risk of wind erosion in Adams County, Washington, WEPS and ArcGIS were used to simulate soil loss and PM10 (particulate matter <10µm in diameter) emissions. On a county-wide...

  2. Improving the detection of wind fields from LIDAR aerosol backscatter using feature extraction

    NASA Astrophysics Data System (ADS)

    Bickel, Brady R.; Rotthoff, Eric R.; Walters, Gage S.; Kane, Timothy J.; Mayor, Shane D.

    2016-04-01

    The tracking of winds and atmospheric features has many applications, from predicting and analyzing weather patterns in the upper and lower atmosphere to monitoring air movement from pig and chicken farms. Doppler LIDAR systems exist to quantify the underlying wind speeds, but cost of these systems can sometimes be relatively high, and processing limitations exist. The alternative is using an incoherent LIDAR system to analyze aerosol backscatter. Improving the detection and analysis of wind information from aerosol backscatter LIDAR systems will allow for the adoption of these relatively low cost instruments in environments where the size, complexity, and cost of other options are prohibitive. Using data from a simple aerosol backscatter LIDAR system, we attempt to extend the processing capabilities by calculating wind vectors through image correlation techniques to improve the detection of wind features.

  3. Healing and hope in the midst of devastation: reflections on Katrina in the aftermath of September 11.

    PubMed

    Owens, Donald P; Schieffler, Danny A; Kahn, Marc J

    2011-09-01

    This article reflects on Hurricane Katrina within the background and context of 9/11. Included are other tragedies experienced in the School of Medicine when, combined with 9/11, laid the foundation for our continued working through Katrina.

  4. Field study and numerical modeling of wind and surface waves at the middle-sized water body

    NASA Astrophysics Data System (ADS)

    Baydakov, Georgy; Kuznetsova, Alexandra; Sergeev, Daniil; Papko, Vladislav; Kandaurov, Alexander; Vdovin, Maxim; Troitskaya, Yuliya

    2015-04-01

    This paper presents the results of field experiments on studying the wind and waves over inland waters, which were carried out at the Gorky Reservoir in 2011-2014. The sensors were positioned at the oceanographic Froude buoy including five two-component ultrasonic sensors WindSonic by Gill Instruments at different levels (0.1, 0.85, 1.3, 2.27, 5.26 meters above the mean water surface level), one water and three air temperature sensors, and three-channel wire wave gauge. From the measured profiles of wind speed, we calculated basic parameters of the atmospheric boundary layer: the friction velocity u*, the wind speed at the standard height of 10 m U10 and the drag coefficient CD. Parameters were obtained in the range of wind speeds of 1-10 m/s. For wind speeds stronger than 3 m/s CD values were lower than those obtained before (see eg. [1,2]) and those predicted by the bulk parameterization. In the range of wind speeds of 3-5 m/s CD values are even lower than the corresponding smooth flow. However, for weak winds (less than 2.5 m/s) CD values considerably higher than expected ones. The main peculiarity of our measurements is very low location of the lowest sensor: 0.1 m against 0.89 m in [1] and 0.5 m in [2]. Moreover, the lowest sensor was not fixed on the mast, but was located on the float and followed the water surface. Analysis shows that the obtained parameters of profile are almost independent on the number of approximated wind speed levels if they include the lowest sensor. But excluding the lowest sensor gave larger values of CD similar to [1] and [2]. These results demonstrate importance of wind speed measuring close to the water surface. The new parameterization of surface drag coefficient was proposed on the basis of the obtained data. The new surface drag parameterization was used in WAVEWATCH III model applied for modeling waves at the reservoir. 1-D spectra of the field experiment were compared with those obtained in the numerical experiments with

  5. Tropical Cyclone Evolution and Water and Energy Fluxes: A Hurricane Katrina Case Study

    NASA Astrophysics Data System (ADS)

    Pinheiro, M. C.; Zhou, Y.

    2015-12-01

    Tropical cyclones are a highly destructive force of nature, characterized by extreme precipitation levels and wind speeds and heavy flooding. There are concerns that climate change will cause changes in the intensity and frequency of tropical cyclones. Therefore, the quantification of the water and energy fluxes that occur during a tropical cyclone's life cycle are important for anticipating the magnitude of damages that are likely to occur. This study used HURDAT2 storm track information and data from the satellite-derived SeaFlux and TRMM products to determine changes in precipitation, wind, and latent and sensible heat throughout the life cycle of Hurricane Katrina. The variables were examined along and around the storm track, taking averages both at stationary 5x5 degree boxes and within the instantaneous hurricane domain. Analysis focused on contributions of convergence and latent heat to the storm evolution and examined how the total flux was related to the storm intensity. Certain features, such as the eye, were not resolved due to the data resolution, but the data captures the general trend of enhanced flux levels that are due to the storm's presence. Analysis also included examination of the water and energy budgets as related to convergence and the sensible and latent heat fluxes.

  6. Petroleum and hazardous material releases from industrial facilities associated with Hurricane Katrina.

    PubMed

    Santella, Nicholas; Steinberg, Laura J; Sengul, Hatice

    2010-04-01

    Hurricane Katrina struck an area dense with industry, causing numerous releases of petroleum and hazardous materials. This study integrates information from a number of sources to describe the frequency, causes, and effects of these releases in order to inform analysis of risk from future hurricanes. Over 200 onshore releases of hazardous chemicals, petroleum, or natural gas were reported. Storm surge was responsible for the majority of petroleum releases and failure of storage tanks was the most common mechanism of release. Of the smaller number of hazardous chemical releases reported, many were associated with flaring from plant startup, shutdown, or process upset. In areas impacted by storm surge, 10% of the facilities within the Risk Management Plan (RMP) and Toxic Release Inventory (TRI) databases and 28% of SIC 1311 facilities experienced accidental releases. In areas subject only to hurricane strength winds, a lower fraction (1% of RMP and TRI and 10% of SIC 1311 facilities) experienced a release while 1% of all facility types reported a release in areas that experienced tropical storm strength winds. Of industrial facilities surveyed, more experienced indirect disruptions such as displacement of workers, loss of electricity and communication systems, and difficulty acquiring supplies and contractors for operations or reconstruction (55%), than experienced releases. To reduce the risk of hazardous material releases and speed the return to normal operations under these difficult conditions, greater attention should be devoted to risk-based facility design and improved prevention and response planning.

  7. Evaluating post-Katrina recovery in Mississippi using repeat photography.

    PubMed

    Burton, Christopher; Mitchell, Jerry T; Cutter, Susan L

    2011-07-01

    Hurricane Katrina of August 2005 had extensive consequences for the state of Mississippi in the United States. Widespread infrastructure and property damage, massive social dislocation, and ecological loss remain among the many challenges faced by communities as they work towards 'normalcy'. This study employs repeat photography to understand differential recovery from Hurricane Katrina in Mississippi. Revealing change with conventional landscape photography, a process known as repeat photography, is common in the natural sciences. Simply stated, repeat photography is the practice of re-photographing the same scene as it appears in an earlier photograph. Photographs were taken at 131 sites every six months over a three-year period. Each photograph was assigned a recovery score and a spatially interpolated recovery surface was generated for each time period. The mapped and graphed results show disparities in the progression of recovery: some communities quickly entered the rebuilding process whereas others have lagged far behind.

  8. Oral history and Hurricane Katrina: reflections on shouts and silences.

    PubMed

    Sloan, Stephen

    2008-01-01

    In the immediate aftermath of Hurricane Katrina in August 2005, many oral historians throughout the nation began to consider the role their methodology could serve in documenting the storm and its aftermath. Interviewing so soon after such a traumatic event creates new considerations for oral history as an approach to recording experience. The problems and possibilities of oral history as such a moment initiated a vibrant discussion on H-Oralhist and at professional meetings in the fall of 2005. This article reflects on many of the topics raised in that dialogue, including issues of historical distance, objectivity, reflection, and emotional trauma. The piece also offers an early review of the work of the Center for Oral History and Cultural Heritage at the University of Southern Mississippi to document the impact of Hurricane Katrina in Mississippi.

  9. The evolution of high-latitude field-aligned currents and magnetospheric dynamics in response to solar wind drivers

    NASA Astrophysics Data System (ADS)

    Bogdanova, Yulia; Vennerstrøm, Susanne; Wild, James; Korth, Haje; Lühr, Hermann; Wing, Simon; Pitout, Frederic

    2016-04-01

    While the statistical behaviour of the solar wind-magnetosphere-ionosphere system is well defined by the Dungey cycle, questions remain on the behaviour of this coupled system during extreme conditions, for example during magnetic storms or periods with long lasting northward IMF, and on how, and how fast, the system reacts to abrupt changes in the solar wind driver. Field-aligned currents play a crucial role in the dynamics of this coupled system as they provide connectivity between different regions and act as channels for energy and momentum transfer. These currents have been investigated in the last decade thanks to observations from low-orbiting satellites, such as CHAMP, Ørsted, DMSP, and the Iridium constellation. However, many previous studies concentrated on the statistical behavior of the current systems or measurements from individual observatories. In this paper we will employ data from Swarm, AMPERE, DMSP, Cluster, SuperDARN and SuperMAG to perform a multi-point study of high-latitude field-aligned current systems evolution and properties and magnetospheric dynamics in response to the solar wind driver, concentrating on the intervals of changes in the IMF orientation and extreme IMF and solar wind conditions.

  10. Interplanetary Magnetic Field Sector from Solar Wind around Pluto (SWAP) Measurements of Heavy Ion Pickup near Pluto

    NASA Astrophysics Data System (ADS)

    Zirnstein, E. J.; McComas, D. J.; Elliott, H. A.; Weidner, S.; Valek, P. W.; Bagenal, F.; Stern, S. A.; Ennico, K.; Olkin, C. B.; Weaver, H. A.; Young, L. A.

    2016-06-01

    On 2015 July 14, the New Horizons spacecraft flew by the Pluto system. The Solar Wind Around Pluto (SWAP) instrument on board New Horizons, which detects ions in the energy per charge range ˜0.035 to 7.5 keV/q, measured the unique interaction between the solar wind and Pluto's atmosphere. Immediately after the closest approach, SWAP detected a burst of heavy ion counts when the instrument's field of view (FOV) was aligned north and south of the Sun-Pluto line and approximately normal to the solar wind flow direction, suggesting their origin as heavy neutral atoms from Pluto that were ionized and being picked up by the solar wind. The trajectories of heavy pickup ions depend on the interplanetary magnetic field (IMF). New Horizons is not equipped with a magnetometer, and we cannot directly measure the IMF. However, we can utilize SWAP's measurements and instrument FOV during this brief period of time to determine the most likely sector of the IMF that could reproduce SWAP's observations of heavy ion pickup. We find that the IMF was most likely in an outward sector, or retrograde to the planets’ motion, during the Pluto encounter, and that the heavy ions detected by SWAP are more likely {{{CH}}4}+ than {{{{N}}}2}+. This supports the existence of a methane exosphere at Pluto.

  11. CMEs, the Tail of the Solar Wind Magnetic Field Distribution, and 11-yr Cosmic Ray Modulation at 1 AU. Revised

    NASA Technical Reports Server (NTRS)

    Cliver, E. W.; Ling, A. G.; Richardson, I. G.

    2003-01-01

    Using a recent classification of the solar wind at 1 AU into its principal components (slow solar wind, high-speed streams, and coronal mass ejections (CMEs) for 1972-2000, we show that the monthly-averaged galactic cosmic ray intensity is anti-correlated with the percentage of time that the Earth is imbedded in CME flows. We suggest that this correlation results primarily from a CME related change in the tail of the distribution function of hourly-averaged values of the solar wind magnetic field (B) between solar minimum and solar maximum. The number of high-B (square proper subset 10 nT) values increases by a factor of approx. 3 from minimum to maximum (from 5% of all hours to 17%), with about two-thirds of this increase due to CMEs. On an hour-to-hour basis, average changes of cosmic ray intensity at Earth become negative for solar wind magnetic field values square proper subset 10 nT.

  12. Earthward directed CMEs seen in large-scale coronal magnetic field changes, SOHO LASCO coronagraph and solar wind

    NASA Astrophysics Data System (ADS)

    Li, Yan; Luhmann, Janet G.; Mulligan, T.; Hoeksema, J. Todd; Arge, C. Nick; Plunkett, S. P.; Cyr, O. C. St.

    2001-11-01

    One picture of coronal mass ejection (CME) initiation relates these events to the expansion into space of previously closed coronal magnetic fields, often part of the helmet streamer belt. The work described here makes use of the potential field source surface model based on updated synoptic photospheric field maps to study the large-scale coronal field changes. We isolate those field lines that change from closed to open configurations (newly opening field lines) by comparing potential field source surface models from adjacent magnetograph observations, wherein the same starting foot points on the photosphere are used. If there are some newly opening field lines between the times of two maps, we assume there was a possibility for CME occurrence(s) between these times. In particular, if there are newly opening field lines near the solar disk center, an earthward directed CME may have been generated. Monitoring the coronal magnetic field behavior can in principle reinforce (or not) days in advance predictions of magnetic storms based on Solar and Heliospheric Observatory (SOHO) Large-Angle Spectrometric Coronagraph (LASCO) halo CMEs. Moreover, the coronal field over the visible hemisphere contains information about the possible geoeffectiveness of a particular CME because it shows the approximate orientation and location of the active arcades. By comparing halo CMEs with the newly opening field lines, the solar wind measurements from Wind and ACE spacecraft and the Dst index, we show that, like soft X-ray sigmoids, disappearing filaments, and Extreme ultraviolet Imaging Telescope (EIT) waves on the disk of the Sun, magnetograph observation-based coronal field models may provide additional information on the likelihood of CME effects at the Earth.

  13. The geography of mortality from Hurricane Katrina in New Orleans

    NASA Astrophysics Data System (ADS)

    Mutter, J. C.; Mara, V.; Jayaprakash, S.; None

    2011-12-01

    Hurricane Katrina was one of the highest mortality disasters in US history. Typical hurricanes of the same strength take very few lives. Katrina's mortality is exceeded only by the so-called Galveston Flood (a hurricane) of 1900 that occurred at a time when forecasting was poor and evacuation was possible only by train or horse. The levee failures in New Orleans were a major contributing factor unique to Katrina. An examination of the characteristics of mortality may give insight into the cause of the great scope of the tragedy and the special vulnerability of those who died. We examine the spatial aspects of mortality. The locations of deceased victims were matched with victim information including age, race and gender for approximately 800 victims (data from Louisiana Department of Health and Hospitals). From this we can analyze for spatial clustering of mortality. We know that Katrina took a particularly heavy toll on the elderly so we can analyze, for instance, whether the elderly were more likely to die in some locations than in others. Similarly, we analyze for gender and race against age (dividing age into five groups this gives 20 categories) as a factory in the geographic distribution of mortality as a way to recover measures of vulnerability. We can also correlate the spatial characteristics of mortality with underlying causes that might contribute to vulnerability. Data is available at a census block level on household income, poverty rates, education, home ownership, car ownership and a variety of other factors that can be correlated with the spatial mortality data. This allows for a multi-parameter estimation of factors that govern mortality in this unusually high mortality event.

  14. Reconstruction of New Orleans after Hurricane Katrina: a research perspective.

    PubMed

    Kates, R W; Colten, C E; Laska, S; Leatherman, S P

    2006-10-01

    Four propositions drawn from 60 years of natural hazard and reconstruction research provide a comparative and historical perspective on the reconstruction of New Orleans after Hurricane Katrina. Decisions taken over its 288-year history that have made New Orleans so vulnerable to Katrina reflect a long-term pattern of societal response to hazard events--reducing consequences to relatively frequent events, and increasing vulnerability to very large and rare events. Thus Katrina's consequences for New Orleans were truly catastrophic--accounting for most of the estimated 1,570 deaths of Louisiana residents and $40-50 billion in monetary losses. A comparative sequence and timing of recovery provides a calendar of historical experience against which to gauge progress in reconstruction. Using this calendar, the emergency post-disaster period appears to be longer in duration than that of any other studied disaster. The restoration period, the time taken to restore urban services for the smaller population, is in keeping with or ahead of historical experience. The effort to reconstruct the physical environment and urban infrastructure is likely to take 8-11 years. Conflicting policy goals for reconstruction of rapid recovery, safety, betterment, and equity are already evident. Actions taken demonstrate the rush to rebuild the familiar in contrast to planning efforts that emphasize betterment. Because disasters tend to accelerate existing economic, social, and political trends, the large losses in housing, population, and employment after Katrina are likely to persist and, at best, only partly recover. However, the possibility of breaking free of this gloomy trajectory is feasible and has some historical precedent. PMID:17003119

  15. Vulnerable populations: Hurricane Katrina as a case study.

    PubMed

    Zoraster, Richard M

    2010-01-01

    Mitigating disaster impact requires identifying risk factors. The increased vulnerability of the physically fragile is easily understood. Less obvious are the socio-economic risk factors, especially within relatively affluent societies. Hurricane Katrina demonstrated many of these risks within the United States. These factors include poverty, home ownership, poor English language proficiency, ethnic minorities, immigrant status, and high-density housing. These risk factors must be considered when planning for disaster preparation, mitigation, and response.

  16. Reconstruction of New Orleans after Hurricane Katrina: A research perspective

    PubMed Central

    Kates, R. W.; Colten, C. E.; Laska, S.; Leatherman, S. P.

    2006-01-01

    Four propositions drawn from 60 years of natural hazard and reconstruction research provide a comparative and historical perspective on the reconstruction of New Orleans after Hurricane Katrina. Decisions taken over its 288-year history that have made New Orleans so vulnerable to Katrina reflect a long-term pattern of societal response to hazard events—reducing consequences to relatively frequent events, and increasing vulnerability to very large and rare events. Thus Katrina's consequences for New Orleans were truly catastrophic—accounting for most of the estimated 1,570 deaths of Louisiana residents and $40–50 billion in monetary losses. A comparative sequence and timing of recovery provides a calendar of historical experience against which to gauge progress in reconstruction. Using this calendar, the emergency postdisaster period appears to be longer in duration than that of any other studied disaster. The restoration period, the time taken to restore urban services for the smaller population, is in keeping with or ahead of historical experience. The effort to reconstruct the physical environment and urban infrastructure is likely to take 8–11 years. Conflicting policy goals for reconstruction of rapid recovery, safety, betterment, and equity are already evident. Actions taken demonstrate the rush to rebuild the familiar in contrast to planning efforts that emphasize betterment. Because disasters tend to accelerate existing economic, social, and political trends, the large losses in housing, population, and employment after Katrina are likely to persist and, at best, only partly recover. However, the possibility of breaking free of this gloomy trajectory is feasible and has some historical precedent. PMID:17003119

  17. Assessing the sensitivity to horizontal resolution of Unified Model simulations of Hurricane Katrina

    NASA Astrophysics Data System (ADS)

    O'Hara, J. P.; Webster, S.

    2012-12-01

    In August 2005 Hurricane Katrina made landfall close to New Orleans with devastating consequences. It was one of the strongest storms to impact the coast of the United States and was also one of the most costly. At peak intensity, its central pressure was 902 hPa and 10 m wind speeds were 175 mph. The extreme nature of this weather system therefore makes it an ideal case study to assess the ability of the Met Office Unified Model to simulate and potentially forecast such phenomena. In this study we assess the ability of the Met Office Unified Model (UM) to simulate Hurricane Katrina at a range of horizontal resolutions. Thus a set of limited area model simulations have been performed at resolutions of 1.5 km, 4 km and 24 km. By careful implementation of the lateral boundary conditions it has been possible to (one way) nest all these simulations inside the 25 km operational global forecast model version of the UM. The configuration of the 1.5 km and 4 km models is based on the 1.5 km and 4 km models used operationally over the UK and hence convection is treated explicitly, whilst the 24 km LAM is configured in the same way as the operational global forecast model and hence convection is parametrized. The simulations are all performed on a 2400 km x 1600 km domain and are all initialised around four days prior to landfall, when the observed central pressure was close to 990 hPa. The initial data for the simulations are ERA-interim analyses with the 25 km global forecast generating hourly LBCs via a series of 24 hour long forecasts initialised from successive 12z analyses. Overall, these simulations have been configured in order to make as clean an assessment as possible of the impact of horizontal resolution on the simulation of Hurricane Katrina. In this presentation we first describe and illustrate results summarising the impact of model resolution on the simulated hurricane. Consistent with the systematic tropical cyclone behaviour of the global forecast model

  18. Mapping the Distribution of Sand Live Oak (Quercus geminata) and Determining Growth Responses to Hurricane Katrina (2005) on Cat Island, Mississippi

    NASA Astrophysics Data System (ADS)

    Funderburk, W.; Carter, G. A.; Harley, G. L.

    2013-12-01

    William R. Funderburk, Gregory A. Carter, Grant Harley Gulf Coast Geospatial Center, University of Southern Mississippi Department of Geography and Geology Stennis Space Center, MS 39529 U.S.A. william.funderburk@usm.edu The Mississippi-Alabama barrier islands serve to buffer mainland coastal areas from the impacts of hurricanes and other extreme weather events. On August 29, 2005, they were impacted heavily by the wind, waves, and storm surges of Hurricane Katrina. The purpose of this study is to determine the growth responses of Quercus geminata, a dominant tree species on Cat Island, MS, in relation to the impact of Hurricane Katrina. Remotely sensed data was utilized in conjunction with ground data to assess growth response post Hurricane Katrina. The main objectives of this study were: 1) determine growth response of Q. geminata through tree ring analysis; 2) understand how Q. geminata adapted to intense weather and climatic phenomena on Cat Island. The hypotheses tested were: 1) growth rates of Q. geminata on Cat Island were decreased by the impact of Hurricane Katrina 2) trees at higher elevations survived or recovered while trees at lower elevations did not recover or died. Decadal scale stability is required for forest stand development on siliciclastic barrier islands. Thus, monitoring the distribution of forest climax community species is key to understanding siliciclastic, subsiding, barrier island geomorphic processes and their relationships to successional patterns and growth rates. Preliminary results indicate that Q. geminata produces a faint growth ring, survive for at least two to three hundred years and is well-adapted to frequent salt water flooding. Cat Island: False color Image

  19. Observations of solar-wind-driven progression of interplanetary magnetic field B{sub Y}-related dayside ionospheric disturbances

    SciTech Connect

    Stauning, P.; Friis-Christensen, E.; Clauer, C.R.

    1995-05-01

    Observations from August 2, and 3, 1991, of poleward progressing, dayside convection disturbances accompanied by geomagnetic perturbations and ionospheric radio wave absorption have been analyzed and compared to variations in the solar wind parameters as observed from the IMP 8 satellite. The convection disturbances appear to start at dayside cusp latitudes from where they progress antisunward to high latitudes. The reported observations have enabled calculations of the progression directions and velocities and precise estimates of the delays between solar wind variations as measured by the IMP 8 satellite and ionospheric convection changes as observed from an array of polar magnetic observatories. The progressing ionospheric disturbance events occur during intervals of southward interplanetary magnetic fields (negative interplanetary magnetic field (IMF) B{sub Z} component); they are found to be closely related to variations of the east-west component B{sub Y} of the IMF. The close coupling between the solar wind and the polar ionosphere(s) is explained in an open magnetospheric model in which the geomagnetic field extending from a localized region of the dayside polar cap merges with the southward interplanetary field. Variations in the IMF B{sub Y} component are reproduced in corresponding modulations of the east-west component of the plasma flow at the ionospheric foot points of the connecting `open` field lines. The perturbations of the plasma flow persist while the open field lines are convected with the ionospheric plasma across part of the dayside polar cap. The observed geomagnetic perturbations result from the combined effects of field-aligned currents and horizontal ionospheric currents, notably the convection-related Hall currents. The associated radio wave absorption events are explained as the result of E region electron heating by the horizontal electric fields associated with the convection enhancements. 48 refs., 16 figs., 3 tabs.

  20. Two cases of toxigenic Vibrio cholerae O1 infection after Hurricanes Katrina and Rita--Louisiana, October 2005.

    PubMed

    2006-01-20

    Louisiana was struck by Hurricane Katrina on August 29, 2005, and by Hurricane Rita on September 24, 2005. The two hurricanes caused unprecedented damage from wind and storm surge to the Louisiana Gulf Coast region, and levee breaks resulted in flooding of large residential areas in and around New Orleans. With the flooding, an immediate public health concern was the potential for outbreaks of infectious diseases, including cholera. Nearly all Vibrio infections in the United States are caused by noncholeragenic Vibrio species (e.g., V. parahaemolyticus, V. vulnificus, and non-O1, non-O139 V. cholerae). Cases of cholera rarely occur in the United States, and cholera epidemics, such as those reported in certain developing countries, are unlikely, even with the extreme flooding caused by the two hurricanes. This report describes the investigation by the Louisiana Office of Public Health and CDC into two cases of toxigenic V. cholerae O1 infection in a Louisiana couple; the cases were attributed to consumption of undercooked or contaminated seafood. Although noncholeragenic Vibrio illnesses were reported in 22 residents of Louisiana and Mississippi after Hurricane Katrina, no epidemic of cholera was identified, and no evidence exists of increased risk to Gulf Coast residents.

  1. Comparison of the Effects of RAS vs. Kain-Fritsch Convective Schemes on Katrina Forecasts with GEOS-5

    NASA Technical Reports Server (NTRS)

    Miller, Timothy L.; Cohen, Charles; Paxton, Jessica; Robertson, F. R. (Pete)

    2009-01-01

    Global forecasts were made with the 0.25-degree latitude version of GEOS-5, with the RAS scheme and with the Kain-Fritsch scheme. Examination was made of the Katrina (2005) hurricane simulation. Replacement of the RAS convective scheme with the K-F scheme results in a much more vigorous Katrina, closer to reality. Still, the result is not as vigorous as reality. In terms of wind maximum, the gap was closed by 50%. The result seems to be due to the RAS scheme drying out the boundary layer, thus hampering the grid-scale secondary circulation and attending cyclone development. The RAS case never developed a full warm core, whereas the K-F case did. Not shown here: The K-F scheme also resulted in a more vigorous storm than when GEOS-5 is run with no convective parameterization. Also not shown: An experiment in which the RAS firing level was moved up by 3 model levels resulted in a stronger, warm-core storm, though not as strong as the K-F case. Effects on storm track were noticed, but not studied.

  2. Using Wind and Temperature Fields to Study Dehydration Mechanisms in the Tropical Tropopause Layer

    NASA Technical Reports Server (NTRS)

    Pittman, Jasna; Miller, Timothy; Robertson, Franklin

    2008-01-01

    The tropics are the main region for troposphere-to-stratosphere transport (TST) of air. One of the dominant mechanisms that control tropical TST of water vapor is freeze-drying by the cold tropical tropopause. This mechanism is supported by evidence from satellite observations of the "tape recorder", where seasonal changes in stratospheric water vapor are in phase with seasonal changes in tropopause temperatures in the tropics. Over the last few years, however, the concept of the tropical tropopause has evolved from a single material surface to a layer called the Tropical Tropopause Layer (TTL). A recent hypothesis on dehydration mechanisms suggests that dehydration and entry point into the stratosphere are not always co-located (Holton and Gettelman, 2001). Instead, dehydration can occur during horizontal advection through Lagrangian 'cold pools', or coldest regions along a parcel's trajectory, as air ascends within the TTL while the entry point into the stratosphere occurs at a different geographical location. In this study, we investigate the impact that these Lagrangian cold pools have on TTL moisture. For this purpose, we use in situ measurements of TTL water vapor obtained aboard NASA's WB-57 aircraft over the Eastern Tropical Pacific, and we compare these measurements to minimum saturation water vapor mixing ratios obtained from three-dimensional backward trajectory calculations. Aircraft measurements show frequent unsaturated conditions, which suggest that the entry value of stratospheric water vapor in this region was not set by local saturation conditions. Trajectory calculations, driven by both ECMWF operational analysis and reanalysis winds and temperature fields, are used to explore the impact (e.g., geographical location, timing, dehydration magnitude) of the Lagrangian cold pools intercepted by the parcels sampled by the aircraft. We find noteworthy differences in the location of the Lagrangian cold pools using the two ECMWF data sets, namely

  3. Going Home after Hurricane Katrina: Determinants of Return Migration and Changes in Affected Areas. Working Paper 428

    ERIC Educational Resources Information Center

    Groen, Jeffrey A.; Polivka, Anne E.

    2009-01-01

    This paper examines the decision of Hurricane Katrina evacuees to return to their pre- Katrina areas and documents how the composition of the Katrina-affected region changed over time. Using data from the Current Population Survey, we show that an evacuee's age and the severity of damage in an evacuee's county of origin are important determinants…

  4. SIMULATION OF FRESHWATER PLUME FROM LAKE PONTCHARTRAIN AND THE MISSISSIPPI RIVER IN THE WAKE OF HURRICANE KATRINA

    EPA Science Inventory

    In the spirit of a post-Katrina response, a three-dimensional hydrodynamic model was set up and applied to the hurricane Katrina affected region of Mississippi River delta, Lake Pontchartran, and the Gulf of Mexico coastline near New Orleans. Following Katrina, there was concern ...

  5. Generation of high-resolution wind fields from the dense meteorological station network WegenerNet in South-Eastern Austria

    NASA Astrophysics Data System (ADS)

    Schlager, Christoph; Kirchengast, Gottfried; Fuchsberger, Jürgen

    2016-04-01

    To investigate weather and climate on a local scale as well as for evaluating regional climate models (RCMs) the Wegener Center at the University of Graz established the long-term field experiment WegenerNet Feldbach region, a dense grid of 153 meteorological stations. The observations of these stations are managed by an automatic WegenerNet Processing system. This system includes a quality check of collected observations and a Data Product Generator (DPG), among other subsystems. Products already implemented in the DPG are gridded weather and climate products, generated from the main parameters temperature, precipitation and relative humidity (Kirchengast et. al., Bull. Amer. Meteor. Soc., 95, 227-242, 2014). Missing elements are gridded wind fields from wind observations. Wind is considered as one of the most difficult meteorological variables to model and depends on many different parameters such as topography and surface roughness. Therefore a simple interpolation can only be performed in case of uniform characteristics of landscape. The presentation introduces our method of generation of wind fields from near real-time observations of the WegenerNet. Purpose of this work is to provide a database with 3D wind fields in a high spatial and time resolution as addition to the existing products, for evaluating convection permitting climate models as well as investigating weather and climate on a local scale. Core of the application is the diagnostic California Meteorological Model (CALMET). This model computes 3D wind fields based on meteorological observational data, a digital elevation model and land use categories. The application generates the required input files from meteorological stations of the WegenerNet Feldbach region and triggers the start of the CALMET model with these input files. In a next step the modeled wind fields are stored automatically every 30 minutes with a spatial resolution of 100 x 100 m in the WegenerNet database. To verify the

  6. Relation between the variations of the solar wind and the noon-time equatorial ionospheric electric fields

    NASA Astrophysics Data System (ADS)

    Manoj, C.; Maus, S.; Alken, P.; Gentile, L.; Burke, W.

    2007-12-01

    We compare the solar wind measurements from ACE satellite with the vertical plasma drift (observed by JULIA radar) and the EEJ magnetic signals (observed at HUA observatory) from the South American equatorial sector. The aim is to understand the effect of solar wind on the variations of the electric field in the noon time equatorial ionosphere. We restrict our study to local noon time conditions, geomagnetically active days and while interplanetary Bz is negative. The estimates of electric field intensities (E_VS) at equatorial plain of the magnetosphere were made from ACE data using a combination of Volland-Stern and Siscoe-Hill models (Burke et al, 2007). The JULIA and magnetometer data were high-pass filtered to remove the regular daily variations. The relation between the data set will be presented as a coherence spectrum. In addition, the use of the ACE measurements to improve the climatological models of EEJ during geomagnetically active days will be explored.

  7. A wind tunnel investigation of the shape of uncharged raindrops in the presence of an external, electric field

    NASA Technical Reports Server (NTRS)

    Pruppacher, H. R.; Rasmussen, R.; Walcek, C.; Wang, P. K.

    1982-01-01

    Results of a wind tunnel experiment in which electrically uncharged water drops of 500 to 3000 microns equivalent radius are freely suspended in the vertical air stream of the UCLA cloud tunnel are presented. During this suspension the drops were exposed to external vertical electric fields of 500 to 8,000 volts/cm. The change in drop shape with drop size and electric field strength was noted and is discussed in the light of theoretical work cited in the literature which unfortunately does not take into account the effects of air flow past the drop. The wind tunnel study is documented by stills from a 16 mm film record that demonstrates the shape of water drops in response to both hydrodynamic and electric forces.

  8. Disturbance of the inclined inserting-type sand fence to wind-sand flow fields and its sand control characteristics

    NASA Astrophysics Data System (ADS)

    Cheng, Jian-jun; Lei, Jia-qiang; Li, Sheng-yu; Wang, Hai-feng

    2016-06-01

    The inclined inserting-type sand fence is a novel sand retaining wall adopted along the Lanxin High-Speed Railway II in Xinjiang for controlling and blocking sand movement. To verify the effectiveness of the new fence structure for sand prevention, a wind tunnel test was used for flow field test simulation of the sand fence. The results indicate that the inclined inserting-type sand fence was able to deflect the flow of the sand and was able to easily form an upward slant acceleration zone on the leeward side of the sand fence. As shown by the percentage change in sand collection rates on the windward side and the leeward side of the sand fence, the sand flux per unit area at 4 m height in the slant upward direction increased on the leeward side of the inclined inserting-type sand fence. By comparing the flow fields, this site is an acceleration zone, which also reaffirms the correspondence of wind-sand flow fields with the spatial distribution characteristic of the wind-carried sand motion. The field sand collection data indicates that under the effects of the inclined inserting-type sand fence, the sandy air currents passing in front and behind the sand fence not only changed in quality, but the grain composition and particle size also significantly changed, suggesting that the inclined inserting-type sand fence has a sorting and filtering effect on the sandy air currents that passed through. The fence retained coarse particulates on the windward side and fine particulates within the shade of the wind on the leeward side.

  9. The impact of changes in the Antarctic wind field on the Southern Ocean sea ice

    NASA Astrophysics Data System (ADS)

    Haid, Verena; Iovino, Dorotea; Masina, Simona

    2016-04-01

    Satellite observations show an enlargement of the sea ice extent of the Southern Ocean in the last decades. A possible trigger for the increase is a change in the atmospheric circulation, which leads to a southward shift and intensification of the westerlies around Antarctica. We performed a sensitivity study with an eddy-permitting sea ice-ocean model forced by ERA-Interim data. We compare a set of numerical simulations with simple manipulations of the wind velocities in the forcing data and investigate the response of sea ice and on-shelf water properties. In our results, increases of the zonal wind component lead to the onset of deep convection in the Weddell Sea within 10 years (with one exception) and a reduction of sea ice. Manipulations of the meridional wind component can lead to an increase of ice extent and volume, but only if regions of strengthened northward wind alternate with regions of increased southward wind. The convergent drift against the shoreline is necessary to thicken the sea ice. Without it, enhanced northward drift leads to an exhanced ice extent during winter but combined with a loss of sea ice thickness which entails a strongly reduced ice extent during summer. For increases of the westward/eastward wind component at the Antarctic coastline, the on-shelf water temperatures increase/decrease due to Ekman pumping. Except for regions with more southerly winds, the manipulated forcing in all cases increases the sea ice production at the coastline and therefore the on-shelf waters are more saline. After a period of 10 years in all the experiments the increased wind results in a higher density of the on-shelf water column.

  10. Controlling Influence of Magnetic Field on Solar Wind Outflow: An Investigation using Current Sheet Source Surface Model

    NASA Astrophysics Data System (ADS)

    Poduval, B.

    2016-08-01

    This Letter presents the results of an investigation into the controlling influence of large-scale magnetic field of the Sun in determining the solar wind outflow using two magnetostatic coronal models: current sheet source surface (CSSS) and potential field source surface. For this, we made use of the Wang and Sheeley inverse correlation between magnetic flux expansion rate (FTE) and observed solar wind speed (SWS) at 1 au. During the period of study, extended over solar cycle 23 and beginning of solar cycle 24, we found that the coefficients of the fitted quadratic equation representing the FTE-SWS inverse relation exhibited significant temporal variation, implying the changing pattern of the influence of FTE on SWS over time. A particularly noteworthy feature is an anomaly in the behavior of the fitted coefficients during the extended minimum, 2008-2010 (CRs 2073-2092), which is considered due to the particularly complex nature of the solar magnetic field during this period. However, this variation was significant only for the CSSS model, though not a systematic dependence on the phase of the solar cycle. Further, we noticed that the CSSS model demonstrated better solar wind prediction during the period of study, which we attribute to the treatment of volume and sheet currents throughout the corona and the more accurate tracing of footpoint locations resulting from the geometry of the model.

  11. Solar Wind Electron Interaction with the Dayside Lunar Surface and Crustal Magnetic Fields: Evidence for Precursor Effects

    NASA Technical Reports Server (NTRS)

    Halekas, Jasper S.; Poppe, A.; Delory, G. T.; Farrell, W. M.; Horanyi, M.

    2012-01-01

    Electron distributions measured by Lunar Prospector above the dayside lunar surface in the solar wind often have an energy dependent loss cone, inconsistent with adiabatic magnetic reflection. Energy dependent reflection suggests the presence of downward parallel electric fields below the spacecraft, possibly indicating the presence of a standing electrostatic structure. Many electron distributions contain apparent low energy (<100 eV) upwardgoing conics (58% of the time) and beams (12% of the time), primarily in regions with non-zero crustal magnetic fields, implying the presence of parallel electric fields and/or wave-particle interactions below the spacecraft. Some, but not all, of the observed energy dependence comes from the energy gained during reflection from a moving obstacle; correctly characterizing electron reflection requires the use of the proper reference frame. Nonadiabatic reflection may also play a role, but cannot fully explain observations. In cases with upward-going beams, we observe partial isotropization of incoming solar wind electrons, possibly indicating streaming and/or whistler instabilities. The Moon may therefore influence solar wind plasma well upstream from its surface. Magnetic anomaly interactions and/or non-monotonic near surface potentials provide the most likely candidates to produce the observed precursor effects, which may help ensure quasi-neutrality upstream from the Moon.

  12. A field evaluation of remote sensor measurements of wind, temperature, and moisture for ARM integrated sounding system research

    SciTech Connect

    Martner, B.E.; Westwater, E.R.; Strauch, R.G.

    1993-10-01

    Remote sensing systems were operated in Colorado in February and March 1991 to obtain detailed profiles of the kinematic and thermodynamic structure of the atmosphere for the US Department of Energy`s Atmospheric Radiation Measurement (ARM) research program. The instruments included wind profilers, Radio Acoustic Sounding Systems (PASS), microwave and infrared radiometers, an infrared spectrometer, ceilometers, radiosondes, surface meteorological stations, and other equipment. A mesoscale data assimilation model will be used to combine the data into dynamically consistent four-dimensional fields as part of an integrated data assimilation sounding system. This report evaluates the performance of the NOAA remote sensors used in the 1991 field data collection. These included five different wind profilers, each equipped with RASS capability for temperature profiling, and microwave radiometers for measurements of pathintegrated water vapor and liquid water content. The design and initial testing of a Fourier-transform InfraRed Sounder (FIRS) for humidity profiling is also described. The ranges of height coverage and measurement accuracies for each wind profiler/RASS are examined. Specific recommendations for optimizing the design and configuration of similar instruments are made for the ARM cloud and Radiation Testbed (CART) sites, based on results of the 1991 field work and earlier tests. Examples of routine processed data products are presented for three intensive operating period studies to further illustrate the remote sensors` capabilities.

  13. Controlling Influence of Magnetic Field on Solar Wind Outflow: An Investigation using Current Sheet Source Surface Model

    NASA Astrophysics Data System (ADS)

    Poduval, B.

    2016-08-01

    This Letter presents the results of an investigation into the controlling influence of large-scale magnetic field of the Sun in determining the solar wind outflow using two magnetostatic coronal models: current sheet source surface (CSSS) and potential field source surface. For this, we made use of the Wang and Sheeley inverse correlation between magnetic flux expansion rate (FTE) and observed solar wind speed (SWS) at 1 au. During the period of study, extended over solar cycle 23 and beginning of solar cycle 24, we found that the coefficients of the fitted quadratic equation representing the FTE–SWS inverse relation exhibited significant temporal variation, implying the changing pattern of the influence of FTE on SWS over time. A particularly noteworthy feature is an anomaly in the behavior of the fitted coefficients during the extended minimum, 2008–2010 (CRs 2073–2092), which is considered due to the particularly complex nature of the solar magnetic field during this period. However, this variation was significant only for the CSSS model, though not a systematic dependence on the phase of the solar cycle. Further, we noticed that the CSSS model demonstrated better solar wind prediction during the period of study, which we attribute to the treatment of volume and sheet currents throughout the corona and the more accurate tracing of footpoint locations resulting from the geometry of the model.

  14. Modeling the magnetospheres of luminous stars: Interactions between supersonic radiation-driven winds and stellar magnetic fields

    SciTech Connect

    Owocki, Stan; Townsend, Rich; Ud-Doula, Asif

    2007-05-15

    Hot, luminous stars (spectral types O and B) lack the hydrogen recombination convection zones that drive magnetic dynamo generation in the sun and other cool stars. Nonetheless, observed rotational modulation of spectral lines formed in the strong, radiatively driven winds of hot stars suggests magnetic perturbations analogous to those that induce 'co-rotating interaction regions' in the solar wind. Indeed, recent advances in spectropolarimetric techniques have now led to direct detection of moderate to strong (100-10 000 G), tilted dipole magnetic fields in several hot stars. Using a combination of analytic and numerical magnetohydrodynamic models, this paper focuses on the role of such magnetic fields in channeling, and sometimes confining, the radiatively driven mass outflows from such stars. The results show how 'magnetically confined wind shocks' can explain the moderately hard x-ray emission seen from the O7V star Theta-1 Ori C, and how the trapping of material in a 'rigidly rotating magnetosphere' can explain the periodically modulated Balmer line emission seen from the magnetic B2pV star Sigma Ori E. In addition, magnetic reconnection heating from episodic centrifugal breakout events might explain the occasional very hard x-ray flares seen from the latter star. The paper concludes with a brief discussion on the generation of hot-star fields and the broader relationship to other types of magnetospheres.

  15. A non-CFD modeling system for computing 3D wind and concentration fields in urban environments

    SciTech Connect

    Nelson, Matthew A; Brown, Michael J; Williams, Michael D; Gowardhan, Akshay; Pardyjak, Eric R

    2010-01-01

    The Quick Urban & Industrial Complex (QUIC) Dispersion Modeling System has been developed to rapidly compute the transport and dispersion of toxic agent releases in the vicinity of buildings. It is composed of an empirical-diagnostic wind solver, an 'urbanized' Lagrangian random-walk model, and a graphical user interface. The code has been used for homeland security and environmental air pollution applications. In this paper, we discuss the wind solver methodology and improvements made to the original Roeckle schemes in order to better capture flow fields in dense built-up areas. The mode1-computed wind and concentration fields are then compared to measurements from several field experiments. Improvements to the QUIC Dispersion Modeling System have been made to account for the inhomogeneous and complex building layouts found in large cities. The logic that has been introduced into the code is described and comparisons of model output to full-scale outdoor urban measurements in Oklahoma City and New York City are given. Although far from perfect, the model agreed fairly well with measurements and in many cases performed equally to CFD codes.

  16. Dependence of SuperDARN-inferred cross polar cap potential upon the solar wind electric field and magnetopause subsolar distance

    NASA Astrophysics Data System (ADS)

    Koustov, Alexandre; Khachikjan, Galina; Sofko, George

    Analysis of statistically significant data set on the cross polar cap potential (CPCP) derived from Super Dual Auroral Radar Network (SuperDARN) measurements for the geoeffective solar wind electric field Ey of up to 12 mV/m is performed. It is shown that if all CPCP data are plotted against Ey, there is a linear increase between 0 and 5 mV/m and saturation at larger values. If the same data are arranged in bins of RMS values, the CPCP depends on Ey linearly in each bin with the slope and intercept of the regression line related to RMS. The inferred linear dependencies CPCP (Ey) for various fixed bins of RMS intersect each other at Ey 2.5-3.0 mV/m, and the character of the CPCP dependence upon the solar wind rum pressure changes at this value. For this reason, the value of 3 mV/m is interpreted as the true threshold of CPCP saturation. This value also corresponds to the condition of the solar wind magnetic field at the subsolar point to be equal to the Earth's dipole field as shown in published MHD simulations. It is argued that the initially inferred saturation threshold of 5 mV/m (for the case of the CPCP data being not sorted according to RMS) is an apparent effect. Presented analysis favors the hypothesis that the CPCP saturates due to shortening of the merging x-line

  17. Evaluation of the Revised Lagrangian Particle Model GRAL Against Wind-Tunnel and Field Observations in the Presence of Obstacles

    NASA Astrophysics Data System (ADS)

    Oettl, Dietmar

    2015-05-01

    A revised microscale flow field model has been implemented in the Lagrangian particle model Graz Lagrangian Model (GRAL) for computing flows around obstacles. It is based on the Reynolds-averaged Navier-Stokes equations in three dimensions and the widely used standard turbulence model. Here we focus on evaluating the model regarding computed concentrations by use of a comprehensive wind-tunnel experiment with numerous combinations of building geometries, stack positions, and locations. In addition, two field experiments carried out in Denmark and in the U.S were used to evaluate the model. Further, two different formulations of the standard deviation of wind component fluctuations have also been investigated, but no clear picture could be drawn in this respect. Overall the model is able to capture several of the main features of pollutant dispersion around obstacles, but at least one future model improvement was identified for stack releases within the recirculation zone of buildings. Regulatory applications are the bread-and-butter of most GRAL users nowadays, requiring fast and robust modelling algorithms. Thus, a few simplifications have been introduced to decrease the computational time required. Although predicted concentrations for the two field experiments were found to be in good agreement with observations, shortcomings were identified regarding the extent of computed recirculation zones for the idealized wind-tunnel building geometries, with approaching flows perpendicular to building faces.

  18. How the Strength and Thickness of Field-aligned Currents Depend on Solar Wind and Ionospheric Parameters

    NASA Astrophysics Data System (ADS)

    Johnson, J.; Wing, S.

    2012-12-01

    Recently, Wing et al. [2011] examined the dependence of field-aligned currents, peak electron energy, and electron energy flux on solar wind parameters. We provide an analytical analysis of how velocity shear layers couple to the ionosphere via field-aligned currents. In the model, we use the Knight relation to express the field-aligned current in terms of the potential drop between the magnetosphere and ionosphere and solve for the ionospheric potential using current continuity. We obtain an analytic expression for the dependence of the current, the current maximum, and the current thickness on the magnetosheath velocity, magnetopause shear layer thickness, magnetospheric density and temperature, and ionospheric conductivity. We compare the analytical results for the current profiles using the magnetic field instruments on board the DMSP satellites. Estimates for FAC strength and thickness allow us to constrain the model to estimate the thickness of the magnetopause velocity shear layer, which is consistent with in situ observations and kinetic simulations. Finally, we discuss how the presence of waves could affect the field-aligned currents. Wing, S., S. Ohtani, J. R. Johnson, M. Echim, P. T. Newell, T. Higuchi, G. Ueno, and G. R. Wilson (2011), Solar wind driving of dayside field-aligned currents, J. Geophys. Res., 116, A08208, doi:10.1029/2011JA016579.

  19. ION KINETIC ENERGY CONSERVATION AND MAGNETIC FIELD STRENGTH CONSTANCY IN MULTI-FLUID SOLAR WIND ALFVÉNIC TURBULENCE

    SciTech Connect

    Matteini, L.; Horbury, T. S.; Schwartz, S. J.; Pantellini, F.; Velli, M.

    2015-03-20

    We investigate the properties of plasma fluid motion in the large-amplitude, low-frequency fluctuations of highly Alfvénic fast solar wind. We show that protons locally conserve total kinetic energy when observed from an effective frame of reference comoving with the fluctuations. For typical properties of the fast wind, this frame can be reasonably identified by alpha particles which, due to their drift with respect to protons at about the Alfvén speed along the magnetic field, do not partake in the fluid low-frequency fluctuations. Using their velocity to transform the proton velocity into the frame of Alfvénic turbulence, we demonstrate that the resulting plasma motion is characterized by a constant absolute value of the velocity, zero electric fields, and aligned velocity and magnetic field vectors as expected for unidirectional Alfvénic fluctuations in equilibrium. We propose that this constraint, via the correlation between velocity and magnetic field in Alfvénic turbulence, is the origin of the observed constancy of the magnetic field; while the constant velocity corresponding to constant energy can only be observed in the frame of the fluctuations, the corresponding constant total magnetic field, invariant for Galilean transformations, remains the observational signature in the spacecraft frame of the constant total energy in the Alfvén turbulence frame.

  20. An Algorithm to Estimate Field Concentrations in the Wake of a Power Plant Complex under Nonsteady Meteorological Conditions from Wind-Tunnel Experiments.

    NASA Astrophysics Data System (ADS)

    Kothari, K. M.; Meroney, R. N.; Bouwmeester, R. J. B.

    1981-08-01

    Highest concentrations of pollutant at ground level are often produced from surface sources with stable or unstable atmospheric conditions and near calm erratic winds. This paper describes a weighted data methodology developed to predict surface concentrations from stationary wind-tunnel measurements and actual meteorological wind fields. Field measurements made downwind of the Rancho Seco Nuclear Power Station in 1975 have been compared against a set of wind-tunnel measurements around a 1:500 scale model of the same facilities. The weighted data algorithm was realistic in both predicting centerline concentration values as well as the horizontal spread of the plume. On the average the wind-tunnel data combined with the weighting algorithm was some 40 times more accurate in predicting field data than the conventional Pasquill-Gifford formulas.

  1. Field Testing of LIDAR-Assisted Feedforward Control Algorithms for Improved Speed Control and Fatigue Load Reduction on a 600-kW Wind Turbine: Preprint

    SciTech Connect

    Kumar, Avishek A.; Bossanyi, Ervin A.; Scholbrock, Andrew K.; Fleming, Paul; Boquet, Mathieu; Krishnamurthy, Raghu

    2015-12-14

    A severe challenge in controlling wind turbines is ensuring controller performance in the presence of a stochastic and unknown wind field, relying on the response of the turbine to generate control actions. Recent technologies such as LIDAR, allow sensing of the wind field before it reaches the rotor. In this work a field-testing campaign to test LIDAR Assisted Control (LAC) has been undertaken on a 600-kW turbine using a fixed, five-beam LIDAR system. The campaign compared the performance of a baseline controller to four LACs with progressively lower levels of feedback using 35 hours of collected data.

  2. Katrina's Children: Social Policy Considerations for Children in Disasters. Social Policy Report. Volume 21, Number 1

    ERIC Educational Resources Information Center

    Osofsky, Joy D.; Osofsky, Howard J.; Harris, William W.

    2007-01-01

    Hurricane Katrina resulted in a disaster of proportions not previously known in the United States. The traumatic experiences of children and families during Hurricane Katrina, the flooding that resulted from the breach of the levees, the evacuation, and the aftermath are unprecedented. In responding to the enormous mental health needs of children…

  3. Satellite imagery maps Hurricane Katrina-induced flooding and oil slicks

    USGS Publications Warehouse

    Rykhus, Russell P.

    2005-01-01

    Katrina also caused major damage to the region's oil and natural gas production and refining capabilities. On 2 September 2005, the Associated Press reported that Katrina had damaged 58 oil platforms, 30 of which were reported lost; one damaged platform had been blown nearly 100 km from its original location.

  4. A National Children's Resiliency Response Initiative: 2006-2007 Plan to Help Katrina's Kids

    ERIC Educational Resources Information Center

    Britt, Alice Mae

    2006-01-01

    The 2006 National Resiliency Response Initiative for Katrina's Kids is a systematic approach to providing resiliency support to the over 200,000 children victimized by one of the worst natural disasters in American history. From the Gulf States region, children suffered trauma during and after Hurricane Katrina as they became displaced young…

  5. How Schools Responded to Student Mental Health Needs Following Hurricanes Katrina and Rita. Fact Sheet

    ERIC Educational Resources Information Center

    RAND Corporation, 2007

    2007-01-01

    This fact sheet summarizes a study that examined how schools in the U.S. Gulf Coast region perceived the mental health needs of students after Hurricanes Katrina and Rita and how schools responded. According to the report, despite strong initial efforts to support the mental health needs of students displaced by Hurricanes Katrina and Rita, many…

  6. Reflecting on "Project Katrina" and Developmentally Appropriate Practices: A Graduate Student's Perspective

    ERIC Educational Resources Information Center

    Schellhaas, Andree; Burts, Diane C.; Aghayan, Carol

    2007-01-01

    This article describes the independent study project of a student who was a graduate assistant in a child development laboratory preschool when Hurricanes Katrina and Rita struck the Gulf Coast area. Through her experiences with "Project Katrina" she deepens her understanding of developmentally appropriate practices as she learns firsthand about…

  7. Out of New Orleans: Race, Class, and Researching the Katrina Diaspora

    ERIC Educational Resources Information Center

    Morris, Jerome E.

    2008-01-01

    The torrential rains from Hurricane Katrina, the breaking of the levees, and the subsequent flooding of New Orleans resulted in another Black Diaspora. This article focuses on Black children and families who were displaced by Hurricane Katrina but now reside in cities, towns, and suburbs outside of the Crescent City. Informed by the author's…

  8. Survivors of the Storm: Teaching in a Post-Katrina World

    ERIC Educational Resources Information Center

    Lowery, Ellen; Burts, Diane C.

    2007-01-01

    This article describes the independent reading and research project of an early childhood education graduate student who taught in a school district heavily impacted by Hurricane Katrina. She surveyed a sample of kindergarten teachers in the district to determine how they were responding in the aftermath of Katrina. The voices of teachers reflect…

  9. Trends in Serious Emotional Disturbance among Youths Exposed to Hurricane Katrina

    ERIC Educational Resources Information Center

    McLaughlin, Katie A.; Fairbank, John A.; Gruber, Michael J.; Jones, Russell T.; Osofsky, Joy D.; Pfefferbaum, Betty; Sampson, Nancy A.; Kessler, Ronald C.

    2010-01-01

    Objective: To examine patterns and predictors of trends in "DSM-IV" serious emotional disturbance (SED) among youths exposed to Hurricane Katrina. Method: A probability sample of adult pre-hurricane residents of the areas affected by Katrina completed baseline and follow-up telephone surveys 18 to 27 months post-hurricane and 12 to 18 months…

  10. Just-in-Time Training: The Lessons of Hurricane Katrina, 10 Years Later

    ERIC Educational Resources Information Center

    Boerner, Heather

    2016-01-01

    Hurricane Katrina reshaped college workforce development programs as thoroughly as it did the coastline--but in this case, the changes were for the good of students, employers and the community. This article discusses the effects and changes made by 4 community colleges who were effected by Hurricane Katrina: (1) Louisiana Community and Technical…

  11. Reactive Aggression and Posttraumatic Stress in Adolescents Affected by Hurricane Katrina

    ERIC Educational Resources Information Center

    Marsee, Monica A.

    2008-01-01

    The current study tests a theoretical model illustrating a potential pathway to reactive aggression through exposure to a traumatic event (Hurricane Katrina) in 166 adolescents (61% female, 63% Caucasian) recruited from high schools on the Gulf Coast of Mississippi. Results support an association between exposure to Hurricane Katrina and reactive…

  12. Cleansing the Superdome: The Paradox of Purity and Post-Katrina Guilt

    ERIC Educational Resources Information Center

    Grano, Daniel A.; Zagacki, Kenneth S.

    2011-01-01

    The reopening of the New Orleans Superdome after Hurricane Katrina on Monday Night Football dramatized problematic rhetorical, visual, and spatial norms of purification rituals bound up in what Burke calls the paradox of purity. Hurricane Katrina was significant as a visually traumatic event in large part because it signified the ghetto as a…

  13. The Dirty Dozen: Twelve Failures of the Hurricane Katrina Response and How Psychology Can Help

    ERIC Educational Resources Information Center

    Gheytanchi, Anahita; Joseph, Lisa; Gierlach, Elaine; Kimpara, Satoko; Housley, Jennifer; Franco, Zeno E.; Beutler, Larry E.

    2007-01-01

    This comprehensive analysis addresses the United States' alarming lack of preparedness to respond effectively to a massive disaster as evidenced by Hurricane Katrina. First, a timeline of problematic response events during and after Hurricane Katrina orients readers to some of the specific problems encountered at different levels of government.…

  14. Observations of the Wind Field in Tornadoes, Funnel Clouds, and Wall Clouds with a Portable Doppler Radar.

    NASA Astrophysics Data System (ADS)

    Bluestein, H. B.; Unruh, W. P.

    1989-12-01

    A severe-storm intercept field program was held in Oklahoma and nearby parts of Texas during the 1987-38 spring seasons. The purpose of the experiment was to use, for the first time, a low-power, portable, continuous-wave (CW), 3-cm Doppler radar to obtain wind spectra in tornadoes from a distance of less than 10 km.We discuss measurements of spectra we recorded in a tornado, a funnel cloud, and two wall clouds. Photographic documentation is also given to aid in the interpretation of our data. Wind speeds as high as 60 m s1 were measured in the tornado. It was found that deploying the portable Doppler radar from a storm-intercept vehicle may increase substantially the number of measurements of wind speeds in tornadoes.The radar has recently been modified so that it has frequency modulation (FM) capability, and hence can obtain wind spectra within range bins. A plan is presented for using the radar to find the source of vorticity in tornadoes.

  15. The Mesospheric Wind Field as Measured by TIMED/TIDI and UARS/HRDI from 2002 to 2005

    NASA Astrophysics Data System (ADS)

    Skinner, W. R.; Gell, D.; Cooper, M.; Niciejewski, R.; Killeen, T. L.; Solomon, S. C.; Wu, Q.; Ortlad, D.; Marshall, A.

    2005-12-01

    The TIMED Doppler Interferometer (TIDI) has been measuring winds in the mesosphere and lower thermosphere since the beginning of 2002. From the beginning of the TIMED mission until March 2005, the High Resolution Doppler Imager (HRDI) on the Upper Atmosphere Satellite (UARS) also measured winds in the same region. It is very desirable to compare the wind field from the two instruments. This three year overlap permits a comprehensive validation of the winds and more importantly allows scientific studies that are difficult or impossible with a single data set. For example, tidal analysis with one instrument requires assumptions about structure of the tide for analysis to proceed. Difficulties in removing instrument artifacts in the TIDI data and correcting for a loss of precision attitude knowledge on the UARS spacecraft have so far prevented these studies. These problems are now largely resolved. This paper will compare the two data sets during the time of mutual operation. The data coverage and accuracies will be discussed as well as the times when the data is best used for validation and when for two instrument scientific studies.

  16. Corollary discharge inhibition of wind-sensitive cercal giant interneurons in the singing field cricket.

    PubMed

    Schöneich, Stefan; Hedwig, Berthold

    2015-01-01

    Crickets carry wind-sensitive mechanoreceptors on their cerci, which, in response to the airflow produced by approaching predators, triggers escape reactions via ascending giant interneurons (GIs). Males also activate their cercal system by air currents generated due to the wing movements underlying sound production. Singing males still respond to external wind stimulation, but are not startled by the self-generated airflow. To investigate how the nervous system discriminates sensory responses to self-generated and external airflow, we intracellularly recorded wind-sensitive afferents and ventral GIs of the cercal escape pathway in fictively singing crickets, a situation lacking any self-stimulation. GI spiking was reduced whenever cercal wind stimulation coincided with singing motor activity. The axonal terminals of cercal afferents showed no indication of presynaptic inhibition during singing. In two ventral GIs, however, a corollary discharge inhibition occurred strictly in phase with the singing motor pattern. Paired intracellular recordings revealed that this inhibition was not mediated by the activity of the previously identified corollary discharge interneuron (CDI) that rhythmically inhibits the auditory pathway during singing. Cercal wind stimulation, however, reduced the spike activity of this CDI by postsynaptic inhibition. Our study reveals how precisely timed corollary discharge inhibition of ventral GIs can prevent self-generated airflow from triggering inadvertent escape responses in singing crickets. The results indicate that the responsiveness of the auditory and wind-sensitive pathway is modulated by distinct CDIs in singing crickets and that the corollary discharge inhibition in the auditory pathway can be attenuated by cercal wind stimulation.

  17. Corollary discharge inhibition of wind-sensitive cercal giant interneurons in the singing field cricket

    PubMed Central

    Hedwig, Berthold

    2014-01-01

    Crickets carry wind-sensitive mechanoreceptors on their cerci, which, in response to the airflow produced by approaching predators, triggers escape reactions via ascending giant interneurons (GIs). Males also activate their cercal system by air currents generated due to the wing movements underlying sound production. Singing males still respond to external wind stimulation, but are not startled by the self-generated airflow. To investigate how the nervous system discriminates sensory responses to self-generated and external airflow, we intracellularly recorded wind-sensitive afferents and ventral GIs of the cercal escape pathway in fictively singing crickets, a situation lacking any self-stimulation. GI spiking was reduced whenever cercal wind stimulation coincided with singing motor activity. The axonal terminals of cercal afferents showed no indication of presynaptic inhibition during singing. In two ventral GIs, however, a corollary discharge inhibition occurred strictly in phase with the singing motor pattern. Paired intracellular recordings revealed that this inhibition was not mediated by the activity of the previously identified corollary discharge interneuron (CDI) that rhythmically inhibits the auditory pathway during singing. Cercal wind stimulation, however, reduced the spike activity of this CDI by postsynaptic inhibition. Our study reveals how precisely timed corollary discharge inhibition of ventral GIs can prevent self-generated airflow from triggering inadvertent escape responses in singing crickets. The results indicate that the responsiveness of the auditory and wind-sensitive pathway is modulated by distinct CDIs in singing crickets and that the corollary discharge inhibition in the auditory pathway can be attenuated by cercal wind stimulation. PMID:25318763

  18. Evaluating Wind Fields from a Diagnostic Model Over Complex Terrain in the Phoenix Region and Implications to Dispersion Calculations for Regional Emergency Response

    SciTech Connect

    Wang, Weiguo; Shaw, William J.

    2009-12-01

    This paper compares the wind field from a diagnostic model (CALMET) over complex terrain in the Phoenix region in the USA with observations that are gridded by a state-of-the-art Four-Dimensional Data Assimilation (FDDA) system. The wind difference between the CALMET and FDDA wind fields is larger at night than in the day. The magnitude of the wind difference can be smaller than 5% of the mean wind speed at low levels in areas with dense observational stations, while it can be larger than 80% in areas without observational stations or at high altitudes. The vector-mean wind direction difference over the domain is 15 deg on the surface level and 25 deg between 10 and 1500 m. To evaluate the effects of the wind difference on dispersion calculations, dispersion of a hypothetical passive tracer released from surface point sources is simulated by the second-order closure integrated puff (SCIPUFF) model driven by the CALMET and FDDA wind fields, respectively. Differences in the two simulated tracer concentration fields increase with time due to accumulation of effects of the wind differences both near the surface and at higher altitudes. Even for the release in the area with the densest distribution of surface stations, the relative difference in the peak surface concentration from CALMET-SCIPUFF and from FDDA-SCIPUFF is less than 10% only within 0.5 hr after the release in the afternoon, and increases to 70% at 1.5 hr; this is because of large differences in wind above the surface. For the release in the area with few stations, the difference can be larger than 100% or even larger after 1.5 hr from the release. To improve dispersion simulations driven by the CALMET wind in the region, observations at upper-air stations are needed and the current surface observation network needs to be reorganized or more stations are needed to account for the influence of terrain.

  19. Ulysses field and plasma observations of magnetic holes in the solar wind and their relation to mirror-mode structures

    NASA Technical Reports Server (NTRS)

    Winterhalter, Daniel; Neugebauer, Marcia; Goldstein, Bruce E.; Smith, Edward J.; Bame, Samuel J.; Balogh, Andre

    1994-01-01

    The term 'magnetic hole' has been used to denote isolated intervals when the magnitude of the interplanetary magnetic field drops to a few tenths, or less, of its ambient value for a time that corresponds to a linear dimension of tens to a few hundreds of proton gyro-radii. Data obtained by the Ulysses magnetometer and solar wind anlayzer have been combined to study the properties of such magnetic holes in the solar wind between 1 AU and 5.4 AU and to 23 deg south latitude. In order to avoid confusion with decreases in field strength at interplanetary discontinuities, the study has focused on linear holes across which the field direction changed by less than 5 deg. The holes occurred preferentially, but not without exception, in the interaction regions on the leading edges of high-speed solar wind streams. Although the plasma surrounding the holes was generally stable against the mirror instability, there are indications that the holes may have been remnants of mirror-mode structures created upstream of the points of observation. Those indications include the following: (1) For the few holes for which proton of alpha-particle pressure could be measured inside the hole, the ion thermal pressure was always greater than in the plasma adjacent to the holes. (2) The plasma surrounding many of the holes was marginally stable for the mirror mode, while the plasma environment of all holes was significantly closer to mirror instability than was the average solar wind. (3) The plasma containing trains of closely spaced holes was closer to mirror instability than was the plasma containing isolated holes. (4) The near-hole plasma had much higher ion beta (ratio of thermal to magnetic pressure) than did the average solar wind. (5) Near the holes, T(sub perp)/T(sub parallel) tended to be either greater than 1 or larger than in the average wind. (6) The proton and alpha-particle distribution functions measured inside the holes occasionally exhibited the flattened phase

  20. Charged Dust Grain Dynamics Subject to Solar Wind, Poynting–Robertson Drag, and the Interplanetary Magnetic Field

    NASA Astrophysics Data System (ADS)

    Lhotka, Christoph; Bourdin, Philippe; Narita, Yasuhito

    2016-09-01

    We investigate the combined effect of solar wind, Poynting–Robertson drag, and the frozen-in interplanetary magnetic field on the motion of charged dust grains in our solar system. For this reason, we derive a secular theory of motion by the means of an averaging method and validate it with numerical simulations of the unaveraged equations of motions. The theory predicts that the secular motion of charged particles is mainly affected by the z-component of the solar magnetic axis, or the normal component of the interplanetary magnetic field. The normal component of the interplanetary magnetic field leads to an increase or decrease of semimajor axis depending on its functional form and sign of charge of the dust grain. It is generally accepted that the combined effects of solar wind and photon absorption and re-emmision (Poynting–Robertson drag) lead to a decrease in semimajor axis on secular timescales. On the contrary, we demonstrate that the interplanetary magnetic field may counteract these drag forces under certain circumstances. We derive a simple relation between the parameters of the magnetic field, the physical properties of the dust grain, as well as the shape and orientation of the orbital ellipse of the particle, which is a necessary conditions for the stabilization in semimajor axis.

  1. Charged Dust Grain Dynamics Subject to Solar Wind, Poynting-Robertson Drag, and the Interplanetary Magnetic Field

    NASA Astrophysics Data System (ADS)

    Lhotka, Christoph; Bourdin, Philippe; Narita, Yasuhito

    2016-09-01

    We investigate the combined effect of solar wind, Poynting-Robertson drag, and the frozen-in interplanetary magnetic field on the motion of charged dust grains in our solar system. For this reason, we derive a secular theory of motion by the means of an averaging method and validate it with numerical simulations of the unaveraged equations of motions. The theory predicts that the secular motion of charged particles is mainly affected by the z-component of the solar magnetic axis, or the normal component of the interplanetary magnetic field. The normal component of the interplanetary magnetic field leads to an increase or decrease of semimajor axis depending on its functional form and sign of charge of the dust grain. It is generally accepted that the combined effects of solar wind and photon absorption and re-emmision (Poynting-Robertson drag) lead to a decrease in semimajor axis on secular timescales. On the contrary, we demonstrate that the interplanetary magnetic field may counteract these drag forces under certain circumstances. We derive a simple relation between the parameters of the magnetic field, the physical properties of the dust grain, as well as the shape and orientation of the orbital ellipse of the particle, which is a necessary conditions for the stabilization in semimajor axis.

  2. The design of a low-speed wind tunnel for studying the flow field of insects' flight

    NASA Astrophysics Data System (ADS)

    Zhao, Hong-yan; Zhang, Peng-fei; Ma, Yun; Ning, Jian-guo

    2015-03-01

    In this paper, low-speed smoke wind tunnel has been designed and fabricated for the insects' flow field visualization. The test section and the contraction section of the tunnel are optimized and determined as to size by the method of computational fluid dynamics. And fairing devices are equipped in different sections to reduce the turbulence intensity and increase the flow uniformity in the experimental sections. For the smoke visualization of small insects, the smokeemitting equipment has been specially designed and carefully debugged. Composed of wind tunnel, light source and high-speed camera, experimental platform for visualization and filming of insect flight flow field has been established. Besides, the feasible and stable method for insect fixing has been designed. With the smoke wind tunnel, flow filed visualization experiment for the honeybee's flapping was conducted and smoke flow filed in the experiment was recorded and analyzed. Near-filed and far-filed vortex structure when the honeybee fly can be recorded clearly. The experimental results indicate that the experimental platform is appropriate for flow filed study on insects flapping.

  3. Relative Contribution of the Magnetic Field Barrier and Solar Wind Speed in ICME-associated Forbush Decreases

    NASA Astrophysics Data System (ADS)

    Bhaskar, Ankush; Subramanian, Prasad; Vichare, Geeta

    2016-09-01

    We study 50 cosmic-ray Forbush decreases (FDs) from the Oulu neutron monitor data during 1997-2005 that were associated with Earth-directed interplanetary coronal mass ejections (ICMEs). Such events are generally thought to arise due to the shielding of cosmic rays by a propagating diffusive barrier. The main processes at work are the diffusion of cosmic rays across the large-scale magnetic fields carried by the ICME and their advection by the solar wind. In an attempt to better understand the relative importance of these effects, we analyze the relationship between the FD profiles and those of the interplanetary magnetic field (B) and the solar wind speed (V sw). Over the entire duration of a given FD, we find that the FD profile is generally (anti)correlated with the B and V sw profiles. This trend holds separately for the FD main and recovery phases too. For the recovery phases, however, the FD profile is highly anti-correlated with the V sw profile, but not with the B profile. While the total duration of the FD profile is similar to that of the V sw profile, it is significantly longer than that of the B profile. Using the convection-diffusion model, a significant contribution of advection by solar wind is found during the recovery phases of the FD.

  4. Transient behavior of flare-associated solar wind. II. Gas dynamics in a nonradial open field region

    SciTech Connect

    Nagai, F.

    1984-03-15

    In this paper, we have numerically investigated the transient perturbation of a fast (''high-speed'') model solar wind in a nonradial open field geometry, taking into account the thermal and dynamical coupling between the chromosphere and the corona. The transient behavior of the fast solar wind is treated between 1 and 8 solar radii, assuming that flare heating occurs in the lower corona. The results are compare with the radial case previously investigated in the first paper in this series. The unperturbed high-speed wind passes through the inner X-type critical point in the rapidly diverging region, where it shows much larger increase in velocity and steeper decrease in density and pressure as compared with the radial case. It is assumed that flare-energy input ceases before the ascending shock reaches the inner critical point, and that the total flare energy per unit area on the surface of the Sun is the same as in the radial case, in spite of the difference in open field geometries.

  5. The relationship among air quality, mixing heights, and winds observed during the entire TexAQS-II field study

    NASA Astrophysics Data System (ADS)

    MacDonald, C.; Knoderer, C. A.; Zahn, P.

    2007-12-01

    The Texas Air Quality Study II (TexAQS-II) was designed to provide support for State Implementation Plan (SIP) revisions. The SIP revisions outline strategies for improving air quality to meet the new federal 8-hr ozone standard and regional haze requirements. As part of TexAQS-II, a field study was conducted to collect air quality and meteorological data throughout eastern Texas from May 1, 2005, through October 15, 2006. As part of the field study, various organizations made upper-air meteorological measurements at several locations. These measurements were collected by twelve 915-MHz radar wind profilers (RWPs), three 404 MHz RWPs, nine Radio Acoustic Sounding Systems (RASS), two sodars, and one lidar. These instruments provide vertically, horizontally, and temporally resolved wind, virtual temperature (Tv), and mixing height information. This presentation will address the three-dimensional and temporal characteristics of these parameters throughout the study domain for the entire study period and how these characteristic vary by season, month, and synoptic weather pattern. The presentation will also address how these characteristics influence regional and local air quality conditions throughout the study domain, including the relationship among various transport statistics, mixing height characteristics (e.g., time of peak mixing, morning mixing height growth rate, peak mixing height, average morning mixing height, etc.) and air quality. In addition, case studies will illustrate the finer-scale details of the relationship among the evolution of mixing heights, diurnal variability of winds, and air quality.

  6. Dependence of the amplitude of Pc5-band magnetic field variations on the solar wind and solar activity

    NASA Astrophysics Data System (ADS)

    Takahashi, Kazue; Yumoto, Kiyohumi; Claudepierre, Seth G.; Sanchez, Ennio R.; Troshichev, Oleg A.; Janzhura, Alexander S.

    2012-04-01

    We have studied the dependence of the amplitude of magnetic field variations in the Pc5 band (1.6-6.7 mHz) on the solar wind and solar activity. Solar wind parameters considered are the bulk velocity Vsw and the variation of the solar wind dynamic pressure δPsw. The solar activity dependence is examined by contrasting observations made in 2001 (solar activity maximum) and 2006 (solar activity declining phase). We calculated hourly Pc5 amplitude using data from geostationary satellites at L = 6.8 and ground stations covering 1 < L < 9. The amplitude is positively correlated with both Vsw and δPsw, but the degree of correlation varies with L and magnetic local time. As measured by the correlation coefficient, the amplitude dependence on both Vsw and δPsw is stronger on the dayside than on the nightside, and the dependence on Vsw (δPsw) tends to be stronger at higher (lower) L, with the relative importance of the two solar wind parameters switching at L ˜ 5. We attribute the Vsw control to the Kelvin-Helmholtz instability on the magnetopause, occurring both at high and low latitudes, and the δPsw control to buffeting of the magnetosphere by variation of solar wind dynamic pressure. The GOES amplitude is higher at the solar maximum at all local times and the same feature is seen on the ground in the dawn sector at L > 6. A radial shift of the fast mode wave turning point, associated with the solar cycle variation of magnetosphere mass density, is a possible cause of this solar activity dependence.

  7. Characteristics of wind-induced loss of solid precipitation derived from a Norwegian field study

    NASA Astrophysics Data System (ADS)

    Petersen-Øverleir, Asgeir; Wolff, Mareile; Isaksen, Ketil; Ødemark, Karianne; Reitan, Trond; Brækkan, Ragnar

    2016-04-01

    Solid precipitation measurements are known to be plagued by under-catch in windy conditions. Adjustment techniques, either based on a dynamic relationship between under-catch and measured determinants or static corrections, are then typically invoked. Such adjustment procedures, especially if the adjustment algorithm is unfit, introduce notable uncertainties that impact hydrological modelling in snow-dominated regions. In 2010, a test-site was established at a mountain plateau in Haukeli, Telemark, Southern Norway. Precipitation data of automatic gauges were compared with a precipitation gauge located in a Double Fence Inter-comparison Reference (DFIR) wind shield construction that served as the reference. A large number of sensors were additionally monitoring supportive meteorological parameters. The study presented in this poster considers data from three winters that were used to study and determine the wind-induced loss of solid precipitation. A general model framework was proposed, and Bayesian methods were used to objectively choose the most plausible sub-model to describe the loss ratio - wind speed - temperature relationship from the Haukeli data. The derived adjustment function is continuous and accounts for measurements of all types of winter precipitation (from rain to dry snow). The analysis shows a non-linear relationship between the loss ratio and wind speed during significant precipitation events, and there is a clear temperature dependency, believed to be mostly related to the precipitation type. The data also displayed a distinctive scatter that is believed to be an artefact mainly caused by neglecting the varying aerodynamic characteristics of the precipitation particles (for a given temperature) as a determinant. The adjustment formula allowed for the first time to derive an adjustment function with a data-tested validity beyond 8-9 m/s and proved a stabilisation of the wind-induced precipitation loss for higher wind speeds. Preliminary tests of

  8. Field-wind Distribution and Eruption Columns: Colima Volcano, México.

    NASA Astrophysics Data System (ADS)

    Fonseca, R.; Martin, A. L.; Perez, I.

    2006-12-01

    Colima Volcano (19º51'N 103º62'W) is characterized by explosive behaviour. Recently this volcano has shown an increase in explosive activity suggesting the possibility of a subplinian event in the next future like the ones occurred in 1818 and 1913. They were characterized by eruptive columns higher than 20 Km. Considering the possibility of a new explosive event we carried out a wind study based on the radiosonde balloon data set (1980-1995) with 15 atmospheric levels. This data set was collected by Global Gridded Upper Air Statistics (GGUAS) of the European Centre for Médium Range Weather Forecast (ECMRWF). The data was processed with a cinematic model for the study of global atmospheric wind circulation. In this model the current function (vorticity) and a potential function (convergency and/or divergency) was calculated with the Poison equation, utilizing a spectral numeric model. Dominant wind direction in January-May and October-December is toward the East with variations to the East/South East. On the contrary during July-September the dominant wind direction is toward the West, South-West, North-East; East and North-East. The fluctuations related to anticyclonic circulation occur in May, July, September and November at the altitude between 5 and 18 Km. The wind model allows identification of the wind horizontal circulation during the whole year at different atmospheric levels. Moreover, the perturbations of the normal circulation have also been identified. These results are applied to an a ash fall map for ash-fall hazard zonification.

  9. Spectral Discrete Probability Density Function of Measured Wind Turbine Noise in the Far Field

    PubMed Central

    Ashtiani, Payam; Denison, Adelaide

    2015-01-01

    Of interest is the spectral character of wind turbine noise at typical residential set-back distances. In this paper, a spectral statistical analysis has been applied to immission measurements conducted at three locations. This method provides discrete probability density functions for the Turbine ONLY component of the measured noise. This analysis is completed for one-third octave sound levels, at integer wind speeds, and is compared to existing metrics for measuring acoustic comfort as well as previous discussions on low-frequency noise sources. PMID:25905097

  10. Spectral discrete probability density function of measured wind turbine noise in the far field.

    PubMed

    Ashtiani, Payam; Denison, Adelaide

    2015-01-01

    Of interest is the spectral character of wind turbine noise at typical residential set-back distances. In this paper, a spectral statistical analysis has been applied to immission measurements conducted at three locations. This method provides discrete probability density functions for the Turbine ONLY component of the measured noise. This analysis is completed for one-third octave sound levels, at integer wind speeds, and is compared to existing metrics for measuring acoustic comfort as well as previous discussions on low-frequency noise sources.

  11. Spectral discrete probability density function of measured wind turbine noise in the far field.

    PubMed

    Ashtiani, Payam; Denison, Adelaide

    2015-01-01

    Of interest is the spectral character of wind turbine noise at typical residential set-back distances. In this paper, a spectral statistical analysis has been applied to immission measurements conducted at three locations. This method provides discrete probability density functions for the Turbine ONLY component of the measured noise. This analysis is completed for one-third octave sound levels, at integer wind speeds, and is compared to existing metrics for measuring acoustic comfort as well as previous discussions on low-frequency noise sources. PMID:25905097

  12. The Dependence of the Strength and Thickness of Field-Aligned Currents on Solar Wind and Ionospheric Parameters

    SciTech Connect

    Johnson, Jay R.; Wing, Simon

    2014-08-01

    Sheared plasma flows at the low-latitude boundary layer correlate well with early afternoon auroral arcs and eld-aligned currents [Sonnerup, 1980; Lundin and Evans, 1985]. We present a simple analytic model that relates solar wind and ionospheric parameters to the strength and thickness of field-aligned currents in a region of sheared velocity, such as the low latitude boundary layer. We compare the predictions of the model with DMSP observations and nd remarkably good scaling of the currents with solar wind and ionospheric parameters. The sheared boundary layer thickness is inferred to be around 3000km consistent with observational studies. The analytic model provides a simple way to organize data and to infer boundary layer structures from ionospheric data.

  13. A Three-Dimensional MHD Simulation of the Solar Wind for a Tilted-Dipole Magnetic Field on the Sun

    NASA Technical Reports Server (NTRS)

    Goldstein, Melvyn L.

    2007-01-01

    Using a three-dimensional MHD model, we simulate the global steady-state structure of the solar corona and solar wind for a dipole magnetic field on the Sun inclined by 30 degrees to the solar rotation axis. This represents the solar conditions typical for a declining phase of solar cycle. The computations can extend from the coronal base out to 100-AU and at large heliospheric distances includes the effects of interstellar neutral hydrogen and their interaction with solar wind protons. The simulations can model the formation of corotating interaction regions and the heliospheric current sheet. The simulations are also capable of describing very strong rarefaction regions that include embedded sub-Alfvenic regions that form on the trailing edge of a fast flows.

  14. Field studies of the potential for wind transport of plutonium- contaminated soils at sites in Areas 6 and 11, Nevada Test Site

    SciTech Connect

    Lancaster, N.; Bamford, R.; Metzger, S.

    1995-07-01

    This report describes and documents a series of field experiments carried out in Areas 6 and 11 of the Nevada Test Site in June and July 1994 to determine parameters of boundary layer winds, surface characteristics, and vegetation cover that can be used to predict dust emissions from the affected sites. Aerodynamic roughness of natural sites is determined largely by the lateral cover of the larger and more permanent roughness elements (shrubs). These provide a complete protection of the surface from wind erosion. Studies using a field-portable wind tunnel demonstrated that natural surfaces in the investigated areas of the Nevada Test Site are stable except at very high wind speeds (probably higher than normally occur, except perhaps in dust devils). However, disturbance of silty-clay surfaces by excavation devices and vehicles reduces the entrainment threshold by approximately 50% and makes these areas potentially very susceptible to wind erosion and transport of sediments.

  15. A physical-model-based, field-wise and self-contained algorithm for removing directional ambiguities of ocean surface winds retrieved from scatterometer measurements

    NASA Astrophysics Data System (ADS)

    Kim, Young-Joon

    2000-09-01

    An algorithm is introduced to remove the directional ambiguities in ocean surface winds measured by scatterometers, which requires scatterometer data only. It is based on two versions of PBL (planetary boundary layer) models and a low-pass filter. A pressure field is first derived from the median-filtered scatterometer winds, is then noise-filtered, and is finally converted back to the winds, respectively, by an inverted PBL model, a smoothing algorithm, and a PBL model. The derived wind field is used to remove the directional ambiguities in the scatterometer data. This new algorithm is applied to Hurricane Eugene and produces results comparable to those from the current standard ambiguity removal algorithm for NASA/JPL SeaWinds project, which requires external numerical weather forecast/analyses data.

  16. Interchange Reconnection and Slow Solar Wind Formation at the boundaries of open field regions in the Solar Corona

    NASA Astrophysics Data System (ADS)

    Rappazzo, A. F.; Matthaeus, W. H.; Ruffolo, D. J.; Servidio, S.; Velli, M.

    2014-12-01

    Interchange reconnection, i.e., magnetic reconnection at the interface between open and closed corona, is thought to contribute to the formation of the slowsolar wind, since it can inject the hotter and denserplasma from closed regions into the heliosphere,and account for the different slow wind composition (thatis similar to the plasma of closed regions) respectto the fast wind. The interchange process has mostly been investigatedfor magnetic field lines with opposite polarity and null points, either for the case of counterdirected loops (e.g., Fisk et al. 1999, Fisk and Schwadron 2001), or in correspondence of null points at the apex of streamers or pseudo-streamers (e.g., Wang et al. 1998,Edmondson et al. 2010, Del Zanna et al. 2011).Magnetic reconnection can certainly occur in these configurations,but they occupy a very small volume of the corona. On the other hand component magnetic reconnection at the boundarybetween coronal holes and streamers or pseudo-streamers hasreceived less attention, even though it can occur aroundthe entire extension of such boundaries. Magnetic reconnection is at the basis of Parker'snanoflare scenario for the heating of coronal loops.Modeling such regions in cartesian geometry with a strongguide field, it has been shown numerically that photosphericmotions induce a magnetic fieldcomponent orthogonal to the strong axial field characterizedby the presence of many current sheets, where the field lines are locally oppositely directed, and can reconnect (Einaudi et al. 1996; Dmitruk and Gomez 1997).The reconnection of the orthogonal component of the magneticfield leads to a change of connectivity of the field linesof the total magnetic field that connect one photospheric boundaryto the other. We have shown that a similar interchange mechanismcan operate in and around the boundaries between open and closedregions inducing a continual stochastic rearrangement of connectivityeverywhere along the open-closed boundary (Rappazzo et al. 2012

  17. Experimental and Numerical Study of Wind and Turbulence in a Near-Field Dispersion Campaign at an Inhomogeneous Site

    NASA Astrophysics Data System (ADS)

    Wei, Xiao; Dupont, Eric; Gilbert, Eric; Musson-Genon, Luc; Carissimo, Bertrand

    2016-09-01

    We present a detailed experimental and numerical study of the local flow field for a pollutant dispersion experimental program conducted at SIRTA (Site Instrumental de Recherche par Télédétection Atmosphérique), a complex and intensively instrumented site in a southern suburb of Paris. Global analysis of continuous measurements over 2 years highlights the impact of terrain heterogeneity on wind and turbulence. It shows that the forest to the north of the experimental field induces strong directional shear and wind deceleration below the forest canopy height. This directional shear is stronger with decreasing height and decreasing distance from the forest edge. Numerical simulations are carried out using Code_Saturne, a computational fluid dynamics code, in Reynolds-averaged Navier-Stokes mode with a standard k{-}ɛ closure and a canopy model, in neutral and stable stratifications. These simulations are shown to reproduce globally well the characteristics of the mean flow, especially the directional wind shear in northeasterly and northwesterly cases and the turbulent kinetic energy increase induced by the forest. However, they slightly underestimate wind speed and the directional shear of the flow below the forest canopy height. Sensitivity studies are performed to investigate the influence of leaf area density, inlet stability condition, and roughness length. These studies show that the typical features of the canopy flow become more pronounced as canopy density increases. Performance statistics indicate that the impact of the forest and adequate inlet profiles are the most important factors in the accurate reproduction of flow at the site, especially under stable stratification.

  18. Pressure Probe Designs for Dynamic Pressure Measurements in a Supersonic Flow Field. [conducted in the Glenn Supersonic Wind Tunnel (SWT)

    NASA Technical Reports Server (NTRS)

    Porro, A. Robert

    2001-01-01

    A series of dynamic flow field pressure probes were developed for use in large-scale supersonic wind tunnels at NASA Glenn Research Center. These flow field probes include pitot, static, and five-hole conical pressure probes that are capable of capturing fast acting flow field pressure transients that occur on a millisecond time scale. The pitot and static probes can be used to determine local Mach number time histories during a transient event. The five-hole conical pressure probes are used primarily to determine local flow angularity, but can also determine local Mach number. These probes were designed, developed, and tested at the NASA Glenn Research Center. They were also used in a NASA Glenn 10- by 10-Foot Supersonic Wind Tunnel (SWT) test program where they successfully acquired flow field pressure data in the vicinity of a propulsion system during an engine compressor stall and inlet unstart transient event. Details of the design, development, and subsequent use of these probes are discussed in this report.

  19. Four-Field Equations: a New Model for Weakly Compressible MHD Turbulence in the Solar Wind and the Interstellar Medium

    NASA Astrophysics Data System (ADS)

    Spangler, S.; Bhattacharjee, A.; Ng, C. S.; Ghosh, S.; Goldstein, M. L.

    1998-11-01

    Turbulent plasmas in the solar wind and the interstellar medium often contain a large directed magnetic field, and the plasma beta (β) is frequently of order unity. To describe the turbulent dynamics of these plasmas, we have derived a system of reduced equations from the fully compressible MHD equations using the Mach number of the turbulent velocity field as a small parameter. These reduced equations constitute a closed system and involve four field variables: the magnetic flux, parallel vorticity, pressure and parallel flow. If β << 1, these equations reduce to the Rosenbluth-Strauss equations or the nearly incompressible MHD (NI-MHD) equations of Zank and Matthaeus. However, for β ~ 1, if the background equilibria have spatial inhomogeneities, the effect of compressibility is shown to enter at leading order. The predictions of the four-field equations are compared with fully compressible MHD simulations, and found to be in agreement. The scaling of density fluctuations with Mach number are compared with solar wind data from Helios 1 and 2, and found to account qualitatively for the scaling range observed.

  20. Alfvénic fluctuations in the solar wind and the orientation of the underlying heliospheric magnetic field

    NASA Astrophysics Data System (ADS)

    Gosling, J. T.; Teh, W.

    2009-12-01

    In their purest form, Alfvénic fluctuations in the solar wind are transverse fluctuations displaying coupled variations in velocity, V, and magnetic field, B, in which |B| remains nearly constant. Consequently, the fluctuations in the component of V and B corresponding to the direction of the underlying magnetic field vector, Bo, upon which the fluctuations are superimposed are always one-sided relative to base values rather than being equitably distributed about average values. Average values of the direction of B in the presence of large-amplitude Alfvénic fluctuations in the solar wind thus generally do not correspond to the direction of Bo, the quantity needed for comparisons with global models of the heliospheric magnetic field and for determining the parallel and perpendicular components of the fluctuation k-vectors. Here we illustrate the one-sided aspect of the fluctuations in Helios 1 data obtained at 0.36 AU at a time when Bo was directed nearly radially outward from the Sun. Using the Helios data and simulated data sets containing large amplitude Alfvénic fluctuations in which the direction of Bo is known precisely we demonstrate that the orientation of the average magnetic field vector, Bav, does not, in general, correspond to the direction of Bo. Minimum variance analysis of our simulated sets of Alfvénic fluctuations in the solar wind demonstrates that the minimum variance direction corresponds roughly to the direction of Bav, consistent with many previous observational studies, but does not correspond to the direction of propagation of the fluctuations, the group velocity of which is directed along Bo.