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Sample records for cloud motion vector

  1. MISR Level 3 Cloud Motion Vector

    Atmospheric Science Data Center

    2013-07-10

    MISR Level 3 Cloud Motion Vector Level 3 Wednesday, November 7, 2012 ... A new version, F02_0002, of the MISR L3 CMV (Cloud Motion Vector) data product is now available. This new release provides finer ... coverage. These enhancements are the result of reorganizing motion vector information present in the recent Level 2 Cloud product as ...

  2. Cloud Motion Vectors from MISR using Sub-pixel Enhancements

    NASA Technical Reports Server (NTRS)

    Davies, Roger; Horvath, Akos; Moroney, Catherine; Zhang, Banglin; Zhu, Yanqiu

    2007-01-01

    The operational retrieval of height-resolved cloud motion vectors by the Multiangle Imaging SpectroRadiometer on the Terra satellite has been significantly improved by using sub-pixel approaches to co-registration and disparity assessment, and by imposing stronger quality control based on the agreement between independent forward and aft triplet retrievals. Analysis of the fore-aft differences indicates that CMVs pass the basic operational quality control 67% of the time, with rms differences - in speed of 2.4 m/s, in direction of 17 deg, and in height assignment of 290 m. The use of enhanced quality control thresholds reduces these rms values to 1.5 m/s, 17 deg and 165 m, respectively, at the cost of reduced coverage to 45%. Use of the enhanced thresholds also eliminates a tendency for the rms differences to increase with height. Comparison of CMVs from an earlier operational version that had slightly weaker quality control, with 6-hour forecast winds from the Global Modeling and Assimilation Office yielded very low bias values and an rms vector difference that ranged from 5 m/s for low clouds to 10 m/s for high clouds.

  3. MISR 17.6 KM Gridded Cloud Motion Vectors: Overview and Assessment

    NASA Technical Reports Server (NTRS)

    Mueller, Kevin; Garay, Michael; Moroney, Catherine; Jovanovic, Veljko

    2012-01-01

    The MISR (Multi-angle Imaging SpectroRadiometer) instrument on the Terra satellite has been retrieving cloud motion vectors (CMVs) globally and almost continuously since early in 2000. In February 2012 the new MISR Level 2 Cloud product was publicly released, providing cloud motion vectors at 17.6 km resolution with improved accuracy and roughly threefold increased coverage relative to the 70.4 km resolution vectors of the current MISR Level 2 Stereo product (which remains available). MISR retrieves both horizontal cloud motion and height from the apparent displacement due to parallax and movement of cloud features across three visible channel (670nm) camera views over a span of 200 seconds. The retrieval has comparable accuracy to operational atmospheric motion vectors from other current sensors, but holds the additional advantage of global coverage and finer precision height retrieval that is insensitive to radiometric calibration. The MISR mission is expected to continue operation for many more years, possibly until 2019, and Level 2 Cloud has the possibility of being produced with a sensing-to-availability lag of 5 hours. This report compares MISR CMV with collocated motion vectors from arctic rawinsonde sites, and from the GOES and MODISTerra instruments. CMV at heights below 3 km exhibit the smallest differences, as small as 3.3 m/s for MISR and GOES. Clouds above 3 km exhibit larger differences, as large as 8.9 m/s for MISR and MODIS. Typical differences are on the order of 6 m/s.

  4. Upgrades to the NOAA/NESDIS automated Cloud-Motion Vector system

    NASA Technical Reports Server (NTRS)

    Nieman, Steve; Menzel, W. Paul; Hayden, Christopher M.; Wanzong, Steve; Velden, Christopher S.

    1993-01-01

    The latest version of the automated cloud motion vector software has yielded significant improvements in the quality of the GOES cloud-drift winds produced operationally by NESDIS. Cloud motion vectors resulting from the automated system are now equal or superior in quality to those which had the benefit of manual quality control a few years ago. The single most important factor in this improvement has been the upgraded auto-editor. Improved tracer selection procedures eliminate targets in difficult regions and allow a higher target density and therefore enhanced coverage in areas of interest. The incorporation of the H2O-intercept height assignment method allows an adequate representation of the heights of semi-transparent clouds in the absence of a CO2-absorption channel. Finally, GOES-8 water-vapor motion winds resulting from the automated system are superior to any done previously by NESDIS and should now be considered as an operational product.

  5. A novel approach for the extraction of cloud motion vectors using airglow imager measurements

    NASA Astrophysics Data System (ADS)

    Satheesh Kumar, S.; Narayana Rao, T.; Taori, A.

    2015-09-01

    The paper explores the possibility of implementing an advanced photogrammetric technique, generally employed for satellite measurements, on airglow imager, a ground-based remote sensing instrument primarily used for upper atmospheric studies, measurements of clouds for the extraction of cloud motion vectors (CMVs). The major steps involved in the algorithm remain the same, including image processing for better visualization of target elements and noise removal, identification of target cloud, setting a proper search window for target cloud tracking, estimation of cloud height, and employing 2-D cross-correlation to estimate the CMVs. Nevertheless, the implementation strategy at each step differs from that of satellite, mainly to suit airglow imager measurements. For instance, climatology of horizontal winds at the measured site has been used to fix the search window for target cloud tracking. The cloud height is estimated very accurately, as required by the algorithm, using simultaneous collocated lidar measurements. High-resolution, both in space and time (4 min), cloud imageries are employed to minimize the errors in retrieved CMVs. The derived winds are evaluated against MST radar-derived winds by considering it as a reference. A very good correspondence is seen between these two wind measurements, both showing similar wind variation. The agreement is also found to be good in both the zonal and meridional wind velocities with RMSEs < 2.4 m s-1. Finally, the strengths and limitations of the algorithm are discussed, with possible solutions, wherever required.

  6. Recent Progress on the Second Generation CMORPH: LEO-IR Based Precipitation Estimates and Cloud Motion Vector

    NASA Astrophysics Data System (ADS)

    Xie, Pingping; Joyce, Robert; Wu, Shaorong

    2015-04-01

    As reported at the EGU General Assembly of 2014, a prototype system was developed for the second generation CMORPH to produce global analyses of 30-min precipitation on a 0.05olat/lon grid over the entire globe from pole to pole through integration of information from satellite observations as well as numerical model simulations. The second generation CMORPH is built upon the Kalman Filter based CMORPH algorithm of Joyce and Xie (2011). Inputs to the system include rainfall and snowfall rate retrievals from passive microwave (PMW) measurements aboard all available low earth orbit (LEO) satellites, precipitation estimates derived from infrared (IR) observations of geostationary (GEO) as well as LEO platforms, and precipitation simulations from numerical global models. Key to the success of the 2nd generation CMORPH, among a couple of other elements, are the development of a LEO-IR based precipitation estimation to fill in the polar gaps and objectively analyzed cloud motion vectors to capture the cloud movements of various spatial scales over the entire globe. In this presentation, we report our recent work on the refinement for these two important algorithm components. The prototype algorithm for the LEO IR precipitation estimation is refined to achieve improved quantitative accuracy and consistency with PMW retrievals. AVHRR IR TBB data from all LEO satellites are first remapped to a 0.05olat/lon grid over the entire globe and in a 30-min interval. Temporally and spatially co-located data pairs of the LEO TBB and inter-calibrated combined satellite PMW retrievals (MWCOMB) are then collected to construct tables. Precipitation at a grid box is derived from the TBB through matching the PDF tables for the TBB and the MWCOMB. This procedure is implemented for different season, latitude band and underlying surface types to account for the variations in the cloud - precipitation relationship. At the meantime, a sub-system is developed to construct analyzed fields of

  7. The effect of the arbitrary level assignment of satellite cloud motion wind vectors on wind analyses in the pre-thunderstorm environment

    NASA Technical Reports Server (NTRS)

    Peslen, C. A.; Koch, S. E.; Uccellini, L. W.

    1985-01-01

    The impact of satellite-derived cloud motion vectors on SESAME rawinsonde wind fields was studied in two separate cases. The effect of wind and moisture gradients on the arbitrary assignment of the satellite data is assessed to coordinate surfaces in a severe storm environment marked by strong vertical wind shear. Objective analyses of SESAME rawinsonde winds and combined winds are produced and differences between these two analyzed fields are used to make an assessment of coordinate level choice. It is shown that the standard method of arbitrarily assigning wind vectors to a low level coordinate surface yields systematic differences between the rawinsonde and combined wind analyses. Arbitrary assignment of cloud motions to the 0.9 sigma surface produces smaller differences than assignment to the 825 mb pressure surface. Systematic differences occur near moisture discontinuities and in regions of horizontal and vertical wind shears. The differences between the combined and SESAME wind fields are made smallest by vertically interpolating cloud motions to either a pressure or sigma surface.

  8. Noctilucent Clouds in Motion

    NASA Video Gallery

    Swedish photographer Peter Rosén took this close-up, time-lapse movieof Noctilucent Clouds (NLCs) over Stockholm, Sweden on the evening ofJuly 16, 2012. "What looked like a serene view from a di...

  9. Wind estimates from cloud motions: Phase 1 of an in situ aircraft verification experiment

    NASA Technical Reports Server (NTRS)

    Hasler, A. F.; Shenk, W. E.; Skillman, W.

    1974-01-01

    An initial experiment was conducted to verify geostationary satellite derived cloud motion wind estimates with in situ aircraft wind velocity measurements. Case histories of one-half hour to two hours were obtained for 3-10km diameter cumulus cloud systems on 6 days. Also, one cirrus cloud case was obtained. In most cases the clouds were discrete enough that both the cloud motion and the ambient wind could be measured with the same aircraft Inertial Navigation System (INS). Since the INS drift error is the same for both the cloud motion and wind measurements, the drift error subtracts out of the relative motion determinations. The magnitude of the vector difference between the cloud motion and the ambient wind at the cloud base averaged 1.2 m/sec. The wind vector at higher levels in the cloud layer differed by about 3 m/sec to 5 m/sec from the cloud motion vector.

  10. Study to determine cloud motion from meteorological satellite data

    NASA Technical Reports Server (NTRS)

    Clark, B. B.

    1972-01-01

    Processing techniques were tested for deducing cloud motion vectors from overlapped portions of pairs of pictures made from meteorological satellites. This was accomplished by programming and testing techniques for estimating pattern motion by means of cross correlation analysis with emphasis placed upon identifying and reducing errors resulting from various factors. Techniques were then selected and incorporated into a cloud motion determination program which included a routine which would select and prepare sample array pairs from the preprocessed test data. The program was then subjected to limited testing with data samples selected from the Nimbus 4 THIR data provided by the 11.5 micron channel.

  11. A Fourier approach to cloud motion estimation

    NASA Technical Reports Server (NTRS)

    Arking, A.; Lo, R. C.; Rosenfield, A.

    1977-01-01

    A Fourier technique is described for estimating cloud motion from pairs of pictures using the phase of the cross spectral density. The method allows motion estimates to be made for individual spatial frequencies, which are related to cloud pattern dimensions. Results obtained are presented and compared with the results of a Fourier domain cross correlation scheme. Using both artificial and real cloud data show that the technique is relatively sensitive to the presence of mixtures of motions, changes in cloud shape, and edge effects.

  12. Motion Estimation System Utilizing Point Cloud Registration

    NASA Technical Reports Server (NTRS)

    Chen, Qi (Inventor)

    2016-01-01

    A system and method of estimation motion of a machine is disclosed. The method may include determining a first point cloud and a second point cloud corresponding to an environment in a vicinity of the machine. The method may further include generating a first extended gaussian image (EGI) for the first point cloud and a second EGI for the second point cloud. The method may further include determining a first EGI segment based on the first EGI and a second EGI segment based on the second EGI. The method may further include determining a first two dimensional distribution for points in the first EGI segment and a second two dimensional distribution for points in the second EGI segment. The method may further include estimating motion of the machine based on the first and second two dimensional distributions.

  13. A Fourier approach to cloud motion estimation

    NASA Technical Reports Server (NTRS)

    Arking, A.; Lo, R. C.; Rosenfeld, A.

    1978-01-01

    A Fourier phase-difference technique for cloud motion estimation from pairs of pictures is described, and results obtained using this technique are compared with the results of a Fourier-domain cross-correlation scheme. The phase-difference technique makes use of the phase of the cross-spectral density and allows motion estimates to be made for individual spatial frequencies, which are related to cloud pattern dimensions. When objects being tracked do not change their shape, size, and orientation to more than a limited degree, both techniques are effective. The phase difference technique is relatively sensitive to the presence of mixtures of motions, changes in cloud shape, and edge effects; in these circumstances, the cross-correlation scheme is preferable. It is suggested that the Fourier transform phase difference estimation methods can be applied in problems such as landmark matching.

  14. Operational cloud-motion winds from Meteosat infrared images

    SciTech Connect

    Schmetz, J.; Holmlund, K.; Mason, B.; Gaertner, V.; Koch, A.; Van De Berg, L. ); Hoffman, J. ); Strauss, B. )

    1993-07-01

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

  15. Cloud motion estimation using a sky imager

    NASA Astrophysics Data System (ADS)

    Chauvin, R.; Nou, J.; Thil, S.; Grieu, S.

    2016-05-01

    The present paper deals with an image processing methodology based on a sky-imaging system developed at the PROMES-CNRS laboratory (France). It is part of a project which aims at improving solar plant control procedures using Direct Normal Irradiance (DNI) forecasts under various sky conditions at short term horizon (5-30 minutes) and high spatial resolution (~1 km2). This work focuses on estimating cloud motion, based on a block-wise cross correlation algorithm. The choice of the algorithm is explained in the first section of this paper. The second section aims at optimizing the algorithm parameters in order to reduce as much as possible the computational time while keeping the best possible accuracy. The paper ends with the spatial and temporal filtering processes that allow estimating the mean cloud motion. The stability of the estimation over time tends to validate the proposed approach.

  16. Relative motion in a debris cloud

    NASA Astrophysics Data System (ADS)

    Kebe, Fatoumata

    2016-07-01

    After an explosion or collision in space, a hundred or thousands of debris are generated. To be able to study a debris cloud it's necessary to develop new analysis tools. In that sense, we have studied several representations of the relative motion with the parent body's orbit as the reference. Thus, in the case of an explosion the original spacecraft has a circular orbit which will be the reference one in the relative motion's equations while, in the case of a collision, we will take one of the spacecraft's orbit as the reference. We mainly focus on the relative motion method that used the differential elements instead of the Cartesian coordinates as it allows to take into account the main perturbation.

  17. Thunderstorm-associated cloud motions as computed from 5-minute SMS pictures. [Synchronous Meteorological Satellite

    NASA Technical Reports Server (NTRS)

    Tecson, J. J.; Umenhofer, T. A.; Fujita, T. T.

    1977-01-01

    The five-minute rapid-scan imagery from the Synchronous Meteorological Satellite is employed to study cloud motions associated with the Omaha tornado of May 6, 1975. Cloud-motion vectors derived from automated and man-machine interactive systems provide an account of the mesoscale phenomena. In addition to the geostationary satellite data, aerial photography obtained during a cloud-truth mission is used in the severe storm investigation. For tracking overland cumuli with short half-lives, a three-minute scan interval appears necessary for the satellite imagery.

  18. Comparison of two schemes for derivation of atmospheric motion vectors

    NASA Astrophysics Data System (ADS)

    Xu, J.; Holmlund, K.; Zhang, Q.; Schmetz, J.

    2002-07-01

    This paper presents the operational scheme of the National Satellite Meteorological Center (NSMC) of the China Meteorological Administration (CMA) to derive atmospheric motion vectors. The NSMC scheme is compared with a method developed at the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT) in preparation for Meteosat Second Generation. Both schemes employ similar basic principles in terms of feature tracking and height assignment, however there are also some important differences. Furthermore, the EUMETSAT scheme assigns quality indicators to each wind vector at the end of the processing chain, whereas the NMSC scheme has inbuilt quality checking at different processing steps allowing for reinstatement of winds rejected by a first quality check. The evaluation of the performance is gained from two periods: a week in January and a week in July 1999. European Centre for Medium-Range Weather Forecast analyses and radiosonde data are used as independent data for evaluation of the two schemes. It is shown that correlating infrared image data with water vapor data before height adjustment, as performed in the NSMC scheme, has a great potential to better distinguish high and low cloud and to provide high-density wind fields. The utilization of radiative transfer calculations for the estimation of the height of thin clouds in the EUMETSAT scheme is shown to be imperative for good quality wind fields. Finally, the feature of the EUMETSAT scheme to assign quality indicators improves the utility of the wind vectors for use in numerical weather prediction models. It is suggested that a combination of the different features of both schemes potentially provide highly increased spatial density in the wind field with improved quality.

  19. Motion/imagery secure cloud enterprise architecture analysis

    NASA Astrophysics Data System (ADS)

    DeLay, John L.

    2012-06-01

    Cloud computing with storage virtualization and new service-oriented architectures brings a new perspective to the aspect of a distributed motion imagery and persistent surveillance enterprise. Our existing research is focused mainly on content management, distributed analytics, WAN distributed cloud networking performance issues of cloud based technologies. The potential of leveraging cloud based technologies for hosting motion imagery, imagery and analytics workflows for DOD and security applications is relatively unexplored. This paper will examine technologies for managing, storing, processing and disseminating motion imagery and imagery within a distributed network environment. Finally, we propose areas for future research in the area of distributed cloud content management enterprises.

  20. Wind estimates from cloud motions: Preliminary results from phases 1, 2, and 3 of an in situ aircraft verification experiment

    NASA Technical Reports Server (NTRS)

    Hasler, A. F.; Shenk, W. E.; Skillman, W. C.

    1975-01-01

    Low level aircraft equipped with Inertial Navigation Systems (INS) were used to define the vertical extent and horizontal motion of a cloud and to measure the ambient wind field. A high level aircraft, also equipped with an INS, took photographs to describe the horizontal extent of the cloud field and to measure cloud motion. The aerial photographs were also used to make a positive identification in a satellite picture of the cloud observed by the low level aircraft. The experiment was conducted over the tropical oceans in the vicinity of Florida, Puerto Rico, Panama and in the Western Gulf of Mexico. Results for tropical cumulus clouds indicate excellent agreement between the cloud motion and the wind at the cloud base. The magnitude of the vector difference between the cloud motion and the cloud base wind is less than 1.3 m/sec for 67% of the cases with track lengths of 1 hour or longer. The cirrus cloud motions agreed best with the mean wind in the cloud layer with a vector difference of about 1.6 m/sec.

  1. Photogrammetry and photo interpretation applied to analyses of cloud cover, cloud type, and cloud motion

    NASA Technical Reports Server (NTRS)

    Larsen, P. A.

    1972-01-01

    A determination was made of the areal extent of terrain obscured by clouds and cloud shadows on a portion of an Apollo 9 photograph at the instant of exposure. This photogrammetrically determined area was then compared to the cloud coverage reported by surface weather observers at approximately the same time and location, as a check on result quality. Stereograms prepared from Apollo 9 vertical photographs, illustrating various percentages of cloud coverage, are presented to help provide a quantitative appreciation of the degradation of terrain photography by clouds and their attendant shadows. A scheme, developed for the U.S. Navy, utilizing pattern recognition techniques for determining cloud motion from sequences of satellite photographs, is summarized. Clouds, turbulence, haze, and solar altitude, four elements of our natural environment which affect aerial photographic missions, are each discussed in terms of their effects on imagery obtained by aerial photography. Data of a type useful to aerial photographic mission planners, expressing photographic ground coverage in terms of flying height above terrain and camera focal length, for a standard aerial photograph format, are provided. Two oblique orbital photographs taken during the Apollo 9 flight are shown, and photo-interpretations, discussing the cloud types imaged and certain visible geographical features, are provided.

  2. Traffic congestion classification using motion vector statistical features

    NASA Astrophysics Data System (ADS)

    Riaz, Amina; Khan, Shoab A.

    2013-12-01

    Due to the rapid increase in population, one of the major problems faced by the urban areas is traffic congestion. In this paper we propose a method for classifying highway traffic congestion using motion vector statistical properties. Motion vectors are estimated using pyramidal Kanada-Lucas-Tomasi (KLT) tracker algorithm. Then motion vector features are extracted and are used to classify the traffic patterns into three categories: light, medium and heavy. Classification using neural network, on publicly available dataset, shows an accuracy of 95.28%, with robustness to environmental conditions such as variable luminance. Our system provides a more accurate solution to the problem as compared to the systems previously proposed.

  3. Volcanic explosion clouds - Density, temperature, and particle content estimates from cloud motion

    NASA Technical Reports Server (NTRS)

    Wilson, L.; Self, S.

    1980-01-01

    Photographic records of 10 vulcanian eruption clouds produced during the 1978 eruption of Fuego Volcano in Guatemala have been analyzed to determine cloud velocity and acceleration at successive stages of expansion. Cloud motion is controlled by air drag (dominant during early, high-speed motion) and buoyancy (dominant during late motion when the cloud is convecting slowly). Cloud densities in the range 0.6 to 1.2 times that of the surrounding atmosphere were obtained by fitting equations of motion for two common cloud shapes (spheres and vertical cylinders) to the observed motions. Analysis of the heat budget of a cloud permits an estimate of cloud temperature and particle weight fraction to be made from the density. Model results suggest that clouds generally reached temperatures within 10 K of that of the surrounding air within 10 seconds of formation and that dense particle weight fractions were less than 2% by this time. The maximum sizes of dense particles supported by motion in the convecting clouds range from 140 to 1700 microns.

  4. Vector Analysis of Human Limb Motion.

    ERIC Educational Resources Information Center

    Laferriere, Joseph E.

    1994-01-01

    Uses vectors to illustrate movement of the human appendicular structures to help students visualize the interaction of the various muscles and understand how a small number of muscles can affect movement in a potentially infinite number of directions. (ZWH)

  5. Clouds on Neptune: Motions, Evolution, and Structure

    NASA Technical Reports Server (NTRS)

    Sromovsky, Larry A.; Morgan, Thomas (Technical Monitor)

    2001-01-01

    The aims of our original proposal were these: (1) improving measurements of Neptune's circulation, (2) understanding the spatial distribution of cloud features, (3) discovery of new cloud features and understanding their evolutionary process, (4) understanding the vertical structure of zonal cloud patterns, (5) defining the structure of discrete cloud features, and (6) defining the near IR albedo and light curve of Triton. Towards these aims we proposed analysis of existing 1996 groundbased NSFCAM/IRTF observations and nearly simultaneous WFPC2 observations from the Hubble Space Telescope. We also proposed to acquire new observations from both HST and the IRTF.

  6. Vector quantization of 3-D point clouds

    NASA Astrophysics Data System (ADS)

    Sim, Jae-Young; Kim, Chang-Su; Lee, Sang-Uk

    2005-10-01

    A geometry compression algorithm for 3-D QSplat data using vector quantization (VQ) is proposed in this work. The positions of child spheres are transformed to the local coordinate system, which is determined by the parent children relationship. The coordinate transform makes child positions more compactly distributed in 3-D space, facilitating effective quantization. Moreover, we develop a constrained encoding method for sphere radii, which guarantees hole-free surface rendering at the decoder side. Simulation results show that the proposed algorithm provides a faithful rendering quality even at low bitrates.

  7. Rapid ray motions in barium plasma clouds and auroras

    NASA Technical Reports Server (NTRS)

    Wescott, E. M.; Hallinan, T. J.; Stenbaek-Nielsen, H. C.; Swift, D. W.; Wallis, D. D.

    1993-01-01

    On two evenings in 1968, anomalous field-aligned brightenings or emission enhancements of up to 3X were observed to move rapidly through three different Ba(+) clouds over Andoya, Norway. Similar effects were observed in Ba(+) clouds released from rockets launched from Poker Flat, Alaska, on March 21, 1973 and on March 22, 1980. On these occasions, auroras on or near the Ba(+) L shell also exhibited active rapid ray motions, which prompts the assumption that the two phenomena are related and the expectation that an explanation of the rapid ray motions in the Ba(+) clouds would lead to a better understanding of the physics of auroral ray motions and the auroral atmosphere. Seven possible mechanisms to produce the observed moving emission enhancements are discussed. The observations provide strong evidence for the existence of transient electric fields of order 100 mV/m at altitudes as low as 200 km during active aurora with rapid ray motions.

  8. Boat detection using vector accumulation of particle motion

    NASA Astrophysics Data System (ADS)

    Zhang, Xuguang; Li, Na; Li, Youyi; Li, Xiaoli

    2014-11-01

    Recently, target detection in sea environment such as boat detection has become a popular research topic which is significant for marine vessels monitoring system. Many target detection methods have been widely applied to practical applications such as frame difference, traditional optical flow and background subtraction method. However, the existing target detection methods are not suitable to deal with the complex conditions of sea surface, such as irregular movement of the waves and illumination changes. In this paper, we developed an approach based on vector accumulation of particle motion mainly aiming at eliminating the effects of irregular movement of waves. Our proposed method applies vector accumulation of particle motion to optical flow field to obtain more accurate detection results under complex conditions. Firstly, the traditional optical flow method is used to acquire motion vector of every particle. Furthermore, the vectors of each flow point are abstracted to represent the recording of a fluid element in the flow over a certain period, succeeding is the accumulation of particle vectors. Finally, we calculate the mean of the vector accumulation to eliminate the effects of irregular movement of waves based on the video. Experimental results show the proposed method can gain better performance than traditional optical flow method.

  9. Cloud Detection of Optical Satellite Images Using Support Vector Machine

    NASA Astrophysics Data System (ADS)

    Lee, Kuan-Yi; Lin, Chao-Hung

    2016-06-01

    Cloud covers are generally present in optical remote-sensing images, which limit the usage of acquired images and increase the difficulty of data analysis, such as image compositing, correction of atmosphere effects, calculations of vegetation induces, land cover classification, and land cover change detection. In previous studies, thresholding is a common and useful method in cloud detection. However, a selected threshold is usually suitable for certain cases or local study areas, and it may be failed in other cases. In other words, thresholding-based methods are data-sensitive. Besides, there are many exceptions to control, and the environment is changed dynamically. Using the same threshold value on various data is not effective. In this study, a threshold-free method based on Support Vector Machine (SVM) is proposed, which can avoid the abovementioned problems. A statistical model is adopted to detect clouds instead of a subjective thresholding-based method, which is the main idea of this study. The features used in a classifier is the key to a successful classification. As a result, Automatic Cloud Cover Assessment (ACCA) algorithm, which is based on physical characteristics of clouds, is used to distinguish the clouds and other objects. In the same way, the algorithm called Fmask (Zhu et al., 2012) uses a lot of thresholds and criteria to screen clouds, cloud shadows, and snow. Therefore, the algorithm of feature extraction is based on the ACCA algorithm and Fmask. Spatial and temporal information are also important for satellite images. Consequently, co-occurrence matrix and temporal variance with uniformity of the major principal axis are used in proposed method. We aim to classify images into three groups: cloud, non-cloud and the others. In experiments, images acquired by the Landsat 7 Enhanced Thematic Mapper Plus (ETM+) and images containing the landscapes of agriculture, snow area, and island are tested. Experiment results demonstrate the detection

  10. The role of the harmonic vector average in motion integration

    PubMed Central

    Johnston, Alan; Scarfe, Peter

    2013-01-01

    The local speeds of object contours vary systematically with the cosine of the angle between the normal component of the local velocity and the global object motion direction. An array of Gabor elements whose speed changes with local spatial orientation in accordance with this pattern can appear to move as a single surface. The apparent direction of motion of plaids and Gabor arrays has variously been proposed to result from feature tracking, vector addition and vector averaging in addition to the geometrically correct global velocity as indicated by the intersection of constraints (IOC) solution. Here a new combination rule, the harmonic vector average (HVA), is introduced, as well as a new algorithm for computing the IOC solution. The vector sum can be discounted as an integration strategy as it increases with the number of elements. The vector average over local vectors that vary in direction always provides an underestimate of the true global speed. The HVA, however, provides the correct global speed and direction for an unbiased sample of local velocities with respect to the global motion direction, as is the case for a simple closed contour. The HVA over biased samples provides an aggregate velocity estimate that can still be combined through an IOC computation to give an accurate estimate of the global velocity, which is not true of the vector average. Psychophysical results for type II Gabor arrays show perceived direction and speed falls close to the IOC direction for Gabor arrays having a wide range of orientations but the IOC prediction fails as the mean orientation shifts away from the global motion direction and the orientation range narrows. In this case perceived velocity generally defaults to the HVA. PMID:24155716

  11. The role of the harmonic vector average in motion integration.

    PubMed

    Johnston, Alan; Scarfe, Peter

    2013-01-01

    The local speeds of object contours vary systematically with the cosine of the angle between the normal component of the local velocity and the global object motion direction. An array of Gabor elements whose speed changes with local spatial orientation in accordance with this pattern can appear to move as a single surface. The apparent direction of motion of plaids and Gabor arrays has variously been proposed to result from feature tracking, vector addition and vector averaging in addition to the geometrically correct global velocity as indicated by the intersection of constraints (IOC) solution. Here a new combination rule, the harmonic vector average (HVA), is introduced, as well as a new algorithm for computing the IOC solution. The vector sum can be discounted as an integration strategy as it increases with the number of elements. The vector average over local vectors that vary in direction always provides an underestimate of the true global speed. The HVA, however, provides the correct global speed and direction for an unbiased sample of local velocities with respect to the global motion direction, as is the case for a simple closed contour. The HVA over biased samples provides an aggregate velocity estimate that can still be combined through an IOC computation to give an accurate estimate of the global velocity, which is not true of the vector average. Psychophysical results for type II Gabor arrays show perceived direction and speed falls close to the IOC direction for Gabor arrays having a wide range of orientations but the IOC prediction fails as the mean orientation shifts away from the global motion direction and the orientation range narrows. In this case perceived velocity generally defaults to the HVA. PMID:24155716

  12. Microturbulence, systematic motions, and line formation in molecular clouds

    NASA Technical Reports Server (NTRS)

    White, R. E.

    1977-01-01

    Microturbulence and systematic motions are viewed as simplifying assumptions made to facilitate treatment of line formation in molecular clouds, and line intensities calculated in the two approximations are compared to estimate how uncertainties about the actual line-broadening mechanism affect the interpretation of molecular emission lines. For lines formed by two-level molecules in an isothermal homogeneous cloud, the alternative assumptions lead to peak and integrated line intensities which agree within the differences (up to a factor of 3) associated with the ignorance of cloud geometry. New multilevel calculations for CO in the same cloud model bear out the generality of this result. It follows that, within the geometrical uncertainties, the Sobolev (1960) approximation may be used confidently in the numerous applications for which this simple cloud model suffices.

  13. Proper Motion of the Magellanic Clouds using SPM

    NASA Astrophysics Data System (ADS)

    Vieira, K.; Girard, T.; van Altena, W.; Zacharias, N.; Casetti, D.; Korchagin, V.; Platais, I.; Monet, D.; López, C.

    2014-06-01

    Absolute proper motions are determined for stars and galaxies to V = 17.5 over a 450 square-degree area that includes the Magellanic Clouds, using photographic and CCD observations of the Yale/San Juan Southern Proper Motion program. Multiple, local relative proper motion measures were combined in an overlap solution using photometrically selected galactic disk stars to define a global relative system that is then transformed to absolute using external galaxies and Hipparcos stars to tie into the ICRS. The resulting catalog is used to derive the mean absolute proper motions of the Magellanic Clouds: (μ_{α}^{} cos δ, μ_{δ}^{})_LMC=(+1.88, +0.37)±(0.27, 0.27) mas yr^-1 and (μ_{α}^{} cos δ, μ_{δ}^{})_SMC=(+1.05, -1.03)±(0.30, 0.29) mas yr^-1, based on best-measured samples of 3822 LMC stars and 964 SMC stars. A dominant portion of the formal errors is due to the estimated uncertainty in the inertial system of the Hipparcos Catalog. A more precise determination was made for the proper motion of the SMC relative to the LMC; (μ_{{α cos δ }}^{}, μ_{δ}^{})_{SMC-LMC}=(-0.91, -1.49)±(0.16, 0.15) mas yr^-1. This differential value is used to estimate of the total velocity difference of the two clouds to within ±54 km s^-1. The absolute proper motion results are consistent with the Clouds' orbits being marginally bound to the Milky Way, albeit on an elongated orbit.

  14. Vertical Motions in Convective Clouds Over Darwin, Australia

    NASA Astrophysics Data System (ADS)

    Mallinson, H.; Schumacher, C.; Ahmed, F.

    2015-12-01

    Vertical motions are essential in parameterizing convection in large-scale models. Yet in tropical systems vertical motions are difficult to obtain, especially in areas of active convection. This study uses three months of profiler data from Darwin, Australia to directly compare vertical velocity and spectrum width with reflectivity at a height of 1 km (a near-surface rain proxy) for shallow, mid-level, and deep convective clouds. Vertical velocities for all convective clouds were also compared to echo-top heights of varying reflectivities to better understand convective cloud dynamics in relation to their vertical structure. In shallow convective clouds (tops <4 km) three distinct regimes appear: a weak up-and downdraft couplet at low reflectivities (0-15 dBz), a robust updraft at moderate reflectivities (20-35 dBz), and strong downdrafts at large reflectivities (>40 dBz). These regimes could represent different stages in the convective cloud life cycle with strong updrafts and moderate reflectivity occurring in the growing phase and strong downdrafts and large reflectivity occurring in the mature phase. The weak up-and downdraft couplet and low reflectivities suggest a dissipating phase. Mid-level convective clouds (tops 4-8 km) also show three distinct regimes: moderate updrafts at low reflectivities (possible growing phase), a weak up-and downdraft couplet at moderate reflectivities (possible dissipating phase), and strong up-and downdrafts at large reflectivities (mature phase). Deep convective clouds (tops >8 km) show strong updrafts above 4 km for all reflectivities with the strongest downdrafts occurring at large reflectivities. While maximum updrafts vary in height and occur at different reflectivities among cloud types, mean downdraft depth never exceeds 3 km and is always strongest at large reflectivities, which may allow better characterization of cold pool properties. Throughout all convective cloud types, spectrum width has the highest values at lower

  15. GOCI Level-2 Processing Improvements and Cloud Motion Analysis

    NASA Technical Reports Server (NTRS)

    Robinson, Wayne

    2015-01-01

    The Ocean Biology Processing Group has been working with the Korean Institute of Ocean Science and Technology (KIOST) to process geosynchronous ocean color data from the GOCI (Geostationary Ocean Color Instrument) aboard the COMS (Communications, Ocean and Meteorological Satellite). The level-2 processing program, l2gen has GOCI processing as an option. Improvements made to that processing are discussed here as well as a discussion about cloud motion effects.

  16. Rapid ray motions in barium plasma clouds and auroras

    SciTech Connect

    Wescott, E.M.; Hallinan, T.J.; Stenbaek-Nielsen, H.C.; Swift, D.W.; Wallis, D.D. )

    1993-03-01

    Barium plasma clouds released at high latitudes characteristically become striated with many field-aligned rays. The rays which often resemble auroral features usually drift as a whole with the E [times] B/B[sup 2] drift of the cloud and alter position only slowly (order or tens of seconds). On two evenings in 1968, in releases from Andoya, Norway, anomalous field-aligned brightenings or emission enhancements of up to 3X were observed to move rapidly (10-20 km/s) through three different Ba[sup +] clouds. Similar effects were observed in Ba[sup +] clouds released from rockets launched from Poker Flat, Alaska: On March 21, 1973, in two Ba thermite releases and on March 22, 1980, in the Ba-shaped charge experiment Miss Peggy.' On these occasions, auroras on or near the Ba[sup +] L shell, also exhibited active rapid ray motions. This leads to the assumption that the two phenomena are related and the expectation that an explanation of the rapid ray motions in the Ba[sup +] clouds would lead to a better understanding of the physics of auroral ray motions and the auroral ionosphere. Seven possible mechanisms to produce the observed moving emission enhancements are discussed. Direct motion of an isolated Ba[sup +] ray past the other rays by E [times] B/B[sup 2] motion seems very unlikely due to the observed variations in the enhancements and the large E field required (> 500 mV/m). Compressional waves do not seem to be of sufficient amplitude or velocity. Absorption or radiation of Doppler shifted Ba[sup +] emissions by ions gyrating or moving at a few kilometers per second seems to be the most promising mechanism for producing the enhancements. The observations provide compelling evidence for the existence of transient electric fields of order 100 mV/m at altitudes as low as 200 km during active aurora with rapid ray motions. The affected regions have dimensions of order a few kilometers across B and move eastward at 10-20 km/s. 36 refs., 10 figs., 1 tab.

  17. Digital video steganalysis using motion vector recovery-based features.

    PubMed

    Deng, Yu; Wu, Yunjie; Zhou, Linna

    2012-07-10

    As a novel digital video steganography, the motion vector (MV)-based steganographic algorithm leverages the MVs as the information carriers to hide the secret messages. The existing steganalyzers based on the statistical characteristics of the spatial/frequency coefficients of the video frames cannot attack the MV-based steganography. In order to detect the presence of information hidden in the MVs of video streams, we design a novel MV recovery algorithm and propose the calibration distance histogram-based statistical features for steganalysis. The support vector machine (SVM) is trained with the proposed features and used as the steganalyzer. Experimental results demonstrate that the proposed steganalyzer can effectively detect the presence of hidden messages and outperform others by the significant improvements in detection accuracy even with low embedding rates. PMID:22781241

  18. Verification of sectoral cloud motion based direct normal irradiance nowcasting from satellite imagery

    NASA Astrophysics Data System (ADS)

    Schroedter-Homscheidt, Marion; Gesell, Gerhard

    2016-05-01

    The successful integration of solar electricity from photovoltaics or concentrating solar power plants into the existing electricity supply requires an electricity production forecast for 48 hours, while any improved surface irradiance forecast over the next upcoming hours is relevant for an optimized operation of the power plant. While numerical weather prediction has been widely assessed and is in commercial use, the short-term nowcasting is still a major field of development. European Commission's FP7 DNICast project is especially focusing on this task and this paper reports about parts of DNICast results. A nowcasting scheme based on Meteosat Second Generation cloud imagery and cloud movement tracking has been developed for Southern Spain as part of a solar production forecasting tool (CSP-FoSyS). It avoids the well-known, but not really satisfying standard cloud motion vector approach by using a sectoral approach and asking the question at which time any cloud structure will affect the power plant. It distinguishes between thin cirrus clouds and other clouds, which typically occur in different heights in the atmosphere and move in different directions. Also, their optical properties are very different - especially for the calculation of direct normal irradiances as required by concentrating solar power plants. Results for Southern Spain show a positive impact of up to 8 hours depending of the time of the day and a RMSD reduction of up to 10% in hourly DNI irradiation compared to day ahead forecasts. This paper presents the verification of this scheme at other locations in Europe and Northern Africa (BSRN and EnerMENA stations) with different cloud conditions. Especially for Jordan and Tunisia as the most relevant countries for CSP in this station list, we also find a positive impact of up to 8 hours.

  19. Characteristics of vertical air motion in isolated convective clouds

    NASA Astrophysics Data System (ADS)

    Yang, Jing; Wang, Zhien; Heymsfield, Andrew J.; French, Jeffrey R.

    2016-08-01

    The vertical velocity and air mass flux in isolated convective clouds are statistically analyzed using aircraft in situ data collected from three field campaigns: High-Plains Cumulus (HiCu) conducted over the midlatitude High Plains, COnvective Precipitation Experiment (COPE) conducted in a midlatitude coastal area, and Ice in Clouds Experiment-Tropical (ICE-T) conducted over a tropical ocean. The results show that small-scale updrafts and downdrafts (< 500 m in diameter) are frequently observed in the three field campaigns, and they make important contributions to the total air mass flux. The probability density functions (PDFs) and profiles of the observed vertical velocity are provided. The PDFs are exponentially distributed. The updrafts generally strengthen with height. Relatively strong updrafts (> 20 m s-1) were sampled in COPE and ICE-T. The observed downdrafts are stronger in HiCu and COPE than in ICE-T. The PDFs of the air mass flux are exponentially distributed as well. The observed maximum air mass flux in updrafts is of the order 104 kg m-1 s-1. The observed air mass flux in the downdrafts is typically a few times smaller in magnitude than that in the updrafts. Since this study only deals with isolated convective clouds, and there are many limitations and sampling issues in aircraft in situ measurements, more observations are needed to better explore the vertical air motion in convective clouds.

  20. Quantifying Changes in Intrinsic Molecular Motion Using Support Vector Machines.

    PubMed

    Leighty, Ralph E; Varma, Sameer

    2013-02-12

    The ensemble of three-dimensional (3-D) configurations exhibited by a molecule, that is, its intrinsic motion, can be altered by several environmental factors, and also by the binding of other molecules. Quantification of such induced changes in intrinsic motion is important because it provides a basis for relating thermodynamic changes to changes in molecular motion. This task is, however, challenging because it requires comparing two high-dimensional data sets. Traditionally, when analyzing molecular simulations, this problem is circumvented by first reducing the dimensions of the two ensembles separately, and then comparing summary statistics from the two ensembles against each other. However, since dimensionality reduction is carried out prior to ensemble comparison, such strategies are susceptible to artifactual biases from information loss. Here, we introduce a method based on support vector machines that yields a normalized quantitative estimate for the difference between two ensembles after comparing them directly against one another. While this method can be applied to any molecular system, including nonbiological molecules and crystals, here, we show how it can be applied to identify the specific regions of a paramyxovirus G protein that are affected by the binding of its preferred human receptor, Ephrin B2. This protein-protein interaction initiates the fusion of the virus with the host cell. Specifically, for every residue in the G protein, we obtain separately a quantitative difference between the ensemble of configurations they sample in the presence and in the absence of Ephrin B2. These ensembles were generated using molecular dynamics simulations. Rank-ordering and then mapping the residues that undergo the greatest change in motion onto the 3-D structure of the G protein reveals that they are clustered primarily on a single contiguous facet of the protein and include the set that is known experimentally to play a vital role in regulating viral

  1. 10 Years of Height Resolved, Cloud-Track, Vector Winds from MISR

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

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

  2. Cloud motions on Venus - Global structure and organization

    NASA Technical Reports Server (NTRS)

    Limaye, S. S.; Suomi, V. E.

    1981-01-01

    Results on cloud motions on Venus obtained over a period of 3.5 days from Mariner 10 television images are presented. The implied atmosphere flow is almost zonal everywhere on the visible disk, and is in the same retrograde sense as the solid planet. Objective analysis of motions suggests the presence of jet cores (-130 m/s) and organized atmospheric waves. The longitudinal mean meridional profile of the zonal component of motion of the ultraviolet features shows presence of a midlatitude jet stream (-110 m/s). The mean zonal component is -97 m/s at the equator. The mean meridional motion at most latitudes is directed toward the pole in either hemisphere and is at least an order of magnitude smaller so that the flow is nearly zonal. A tentative conclusion from the limited coverage available from Mariner 10 is that at the level of ultraviolet features mean meridional circulation is the dominant mode of poleward angular momentum transfer as opposed to the eddy circulation.

  3. Generation and utilisation of quality indicators for satellite-derived atmospheric motion vectors

    NASA Astrophysics Data System (ADS)

    Holmlund, Kenneth

    The extraction of Atmospheric Motion Vectors (AMVs) from cloud and moisture features from successive geostationary satellite images is an established and important part of the global observing system. One of the main problems in the utilisation of this data is the variable quality of the derived displacement vectors. Furthermore the AMVs are still currently used as single point measurements, even though they are generally based on targets that represent large areas and the height that is assigned to the vectors often represents a layer mean. In the early AMV derivation schemes the derived vector fields were quality controlled by experienced meteorologists and poor vectors were removed. Furthermore any suspect vector showing any kind of deviations in time and space was rejected and hence only about 17% of all possible vectors were disseminated. Today the high production frequency and the increased resolution make manual quality control unfeasible. Furthermore the new assimilation schemes utilised in Numerical Weather Prediction (NWP) require qualitative information on the errors of the individual AMVs. This Thesis describes an Automatic Quality Control (AQC) scheme that is based on the statistical properties of the derived AMVs. The properties of the AMVs, i.e. their consistency in time and space, are interpreted with a number of tests. The outcome of each test is normalised such that they can be combined to a Quality Indicator (QI) that gives an estimation of the expected quality of every individual vector as is shown by statistics against radiosondes and verified by the positive impact in data assimilation schemes. The QIs are currently derived and disseminated together with the derived AMVs by several operational AMV derivation centres. Only a small number of vectors are now removed before dissemination. The QIs are used operationally for data selection at various NWT centres and have alleviated some of the problems related to the assimilation of this data in NWT

  4. Improvement of image deblurring for opto-electronic joint transform correlator under projective motion vector estimation

    NASA Astrophysics Data System (ADS)

    Xiao, Xiao; Zhao, Hui; Zhang, Yang

    2014-06-01

    In this paper we propose an efficient algorithm to improve the performance of image deblurring based on opto-electronic joint transform correlator (JTC) that is capable of detecting the motion vector of a space camera. Firstly, the motion vector obtained from JTC is divided into many sub-motion vectors according to the projective motion path, which represents the degraded image as an integration of the clear scene under a sequence of planar projective transforms. Secondly, these sub-motion vectors are incorporated into the projective motion Richardson-Lucy (RL) algorithm to improve deblurred results. The simulation results demonstrate the effectiveness of the algorithm and the influence of noise on the algorithm performance is also statically analyzed.

  5. Comparison of Kalpana-1 atmospheric motion vectors with other observations

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

    The operational derivation of atmospheric motion vectors (AMVs) using infrared (10.5-12.5 μm) and water vapor (6.3-7.1 μm) channels of successive geostationary satellite images started in the 1980s. Subsequently, AMVs have become an important component for operational numerical weather prediction throughout the globe for the last decade or so. In India, at the Space Applications Centre, Indian Space Research Organisation, the operational derivation of AMVs (infrared winds and water vapor winds) from the Indian geostationary satellite Kalpana-1 has been initiated a few years back. Recently, an L-band radar lower atmosphere wind profiler (LAWP) has been installed at the National Atmospheric Research Laboratory, Gadanki located at (13.58°N, 79.28°E) for continuous high-resolution wind measurements in the lower atmosphere. In this study, a comparison of Kalpana-1 AMVs with wind measurements from LAWP and radiosonde has been carried out for a period of one and a half years. The performances of Kalpana-1 AMVs are also assessed by a separate comparison of Meteosat-7 AMVs, derived at the European Organisation for the Exploitation of Meteorological Satellites, with wind measurements from LAWP and radiosonde. Both sets of comparison show that AMVs from Kalpana-1 and Meteosat-7 are comparable over the Indian Ocean region.

  6. Self-powered thin-film motion vector sensor

    PubMed Central

    Jing, Qingshen; Xie, Yannan; Zhu, Guang; Han, Ray P. S.; Wang, Zhong Lin

    2015-01-01

    Harnessing random micromeso-scale ambient energy is not only clean and sustainable, but it also enables self-powered sensors and devices to be realized. Here we report a robust and self-powered kinematic vector sensor fabricated using highly pliable organic films that can be bent to spread over curved and uneven surfaces. The device derives its operational energy from a close-proximity triboelectrification of two surfaces: a polytetrafluoroethylene film coated with a two-column array of copper electrodes that constitutes the mover and a polyimide film with the top and bottom surfaces coated with a two-column aligned array of copper electrodes that comprises the stator. During relative reciprocations, the electrodes in the mover generate electric signals of ±5 V to attain a peak power density of ≥65 mW m−2 at a speed of 0.3 ms−1. From our 86,000 sliding motion tests of kinematic measurements, the sensor exhibits excellent stability, repeatability and strong signal durability. PMID:26271603

  7. Semi-fixed-length motion vector coding for H.263-based low bit rate video compression.

    PubMed

    Côté, G; Gallant, M; Kossentini, F

    1999-01-01

    We present a semi-fixed-length motion vector coding method for H.263-based low bit rate video compression. The method exploits structural constraints within the motion field. The motion vectors are encoded using semi-fixed-length codes, yielding essentially the same levels of rate-distortion performance and subjective quality achieved by H.263's Huffman-based variable length codes in a noiseless environment. However, such codes provide substantially higher error resilience in a noisy environment. PMID:18267417

  8. Landsat 7 Reveals Large-scale Fractal Motion of Clouds

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This Landsat 7 image of clouds off the Chilean coast near the Juan Fernandez Islands (also known as the Robinson Crusoe Islands) on September 15, 1999, shows a unique pattern called a 'von Karman vortex street.' This pattern has long been studied in the laboratory, where the vortices are created by oil flowing past a cylindrical obstacle, making a string of vortices only several tens of centimeters long. Study of this classic 'flow past a circular cylinder' has been very important in the understanding of laminar and turbulent fluid flow that controls a wide variety of phenomena, from the lift under an aircraft wing to Earth's weather. Here, the cylinder is replaced by Alejandro Selkirk Island (named after the true 'Robinson Crusoe,' who was stranded here for many months in the early 1700s). The island is about 1.5 km in diameter, and rises 1.6 km into a layer of marine stratocumulus clouds. This type of cloud is important for its strong cooling of the Earth's surface, partially counteracting the Greenhouse warming. An extended, steady equatorward wind creates vortices with clockwise flow off the eastern edge and counterclockwise flow off the western edge of the island. The vortices grow as they advect hundreds of kilometers downwind, making a street 10,000 times longer than those made in the laboratory. Observing the same phenomenon extended over such a wide range of sizes dramatizes the 'fractal' nature of atmospheric convection and clouds. Fractals are characteristic of fluid flow and other dynamic systems that exhibit 'chaotic' motions. Both clockwise and counter-clockwise vortices are generated by flow around the island. As the flow separates from the island's leeward (away from the source of the wind) side, the vortices 'swallow' some of the clear air over the island. (Much of the island air is cloudless due to a local 'land breeze' circulation set up by the larger heat capacity of the waters surrounding the island.) The 'swallowed' gulps of clear island air

  9. Vector Constants of Motion for Time-Dependent Kepler and Isotropic Harmonic Oscillator Potentials

    NASA Astrophysics Data System (ADS)

    Ritter, O. M.; Santos, F. C.; Tort, A. C.

    2001-06-01

    A method of obtaining vector constants of motion for time-independent as well as time-dependent central fields is discussed. Some well-established results are rederived in this alternative way and new ones obtained.

  10. Frame rate upconversion using pyramid structure and dense motion vector fields

    NASA Astrophysics Data System (ADS)

    Kim, Jun-Geon; Lee, Daeho

    2016-05-01

    We propose a frame rate upconversion (FRUC) method using pyramid structures (PS) and dense motion vector fields (MVFs). In FRUC processes, performance is dominantly dependent on motion compensation, thus motion vectors (MVs) must be precisely estimated. Variable sizes of blocks and large search ranges are needed to estimate the MVs of large objects and large movements; however, we use PS and dense MVFs to estimate MVs for various conditions. In the PS, we first estimate MVs on level 0, which is the most reduced image in the PS (L-1 times downsampling), and MVs on the high levels are estimated except for pixels having large corresponding MVs on the lower levels. Integration of MVFs for all levels is followed by a vector median filter to remove noises. Finally, a motion compensated frame is interpolated by weight-overlapped block motion compensation.

  11. Effect of GOES-R Image Navigation and Registration Errors on Atmospheric Motion Vectors

    NASA Technical Reports Server (NTRS)

    Jedlovec, Gary

    2008-01-01

    High temporal frequency imagery from geostationary satellites allows for the continuous monitoring of rapidly changing atmospheric constituents such as smoke, dust, water vapor and clouds. The image sequences are often used to quantify the displacement of image features such as water vapor and clouds to produce atmospheric motion vectors (AMVs) which are used as diagnostic tools and also assimilated into numerical weather forecast models. The basic principle behind the determination of AMVs is the calculation of the physical displacement of features from one image (time) to the next. This process assumes that the features being tracked do not change as a function of time, usually requiring the use of short time interval imagery to minimize substantial change in size and shape of the features being tracked. High spatial resolution imagery also is required for reliable feature identification. While these image resolution and temporal sampling requirements often provide major drivers for space-based instrument design requirements, accurate image navigation and registration, INn (between a sequence of images), is also critical to the derivation of useful AMVs. In this paper and poster to be presented at the conference, the image navigation and registration (INR) accuracy expected for the Advanced Baseline Imager (ABI) on the GOES-R series of satellites will be discussed in light of its impact on AMV accuracy. Significant satellite platform and modeling enhancements are planned which should significantly improve INn performance of the GOES-R instruments. Some of these improvements have been demonstrated for the GOES-13 satellite which was launched in summer of 2006. An analysis of GOES-13 INR data, from the special satellite check out period, will be used in the assessment.

  12. Validation of INSAT-3D atmospheric motion vectors for monsoon 2015

    NASA Astrophysics Data System (ADS)

    Sharma, Priti; Rani, S. Indira; Das Gupta, M.

    2016-05-01

    Atmospheric Motion Vector (AMV) over Indian Ocean and surrounding region is one of the most important sources of tropospheric wind information assimilated in numerical weather prediction (NWP) system. Earlier studies showed that the quality of Indian geo-stationary satellite Kalpana-1 AMVs was not comparable to that of other geostationary satellites over this region and hence not used in NWP system. Indian satellite INSAT-3D was successfully launched on July 26, 2013 with upgraded imaging system as compared to that of previous Indian satellite Kalpana-1. INSAT-3D has middle infrared band (3.80 - 4.00 μm) which is capable of night time pictures of low clouds and fog. Three consecutive images of 30-minutes interval are used to derive the AMVs. New height assignment scheme (using NWP first guess and replacing old empirical GA method) along with modified quality control scheme were implemented for deriving INSAT-3D AMVs. In this paper an attempt has been made to validate these AMVs against in-situ observations as well as against NCMRWF's NWP first guess for monsoon 2015. AMVs are subdivided into three different pressure levels in the vertical viz. low (1000 - 700 hPa), middle (700 - 400 hPa) and high (400 - 100 hPa) for validation purpose. Several statistics viz. normalized root mean square vector difference; biases etc. have been computed over different latitudinal belt. Result shows that the general mean monsoon circulations along with all the transient monsoon systems are well captured by INSAT-3D AMVs, as well as the error statistics viz., RMSE etc of INSAT-3D AMVs is now comparable to other geostationary satellites.

  13. Cloud morphology and motions from Pioneer Venus images

    NASA Technical Reports Server (NTRS)

    Rossow, W. B.; Del Genio, A. D.; Limaye, S. S.; Travis, L. D.; Stone, P. H.

    1980-01-01

    The horizontal and vertical cloud structures, atmospheric waves, and wind velocities at the cloud top level were determined by the Pioneer Venus photopolarimeter images in the UV from January through March 1979. The images indicate long-term evolution of cloud characteristics, the atmospheric dynamics, and rapid small changes in cloud morphology. The clouds show a globally coordinated oscillation relative to latitude circles; retrograde zonal winds of 100 m/s near the equator are determined from the tracking of small-scale cloud properties, but two hemispheres show important variations. The zonal wind velocity in the southern hemisphere is reduced toward the poles at a rate similar to solid body rotation; the midlatitude jet stream noted by Mariner 10 is not observed.

  14. The electronic image stabilization technology research based on improved optical-flow motion vector estimation

    NASA Astrophysics Data System (ADS)

    Wang, Chao; Ji, Ming; Zhang, Ying; Jiang, Wentao; Lu, Xiaoyan; Wang, Jiaoying; Yang, Heng

    2016-01-01

    The electronic image stabilization technology based on improved optical-flow motion vector estimation technique can effectively improve the non normal shift, such as jitter, rotation and so on. Firstly, the ORB features are extracted from the image, a set of regions are built on these features; Secondly, the optical-flow vector is computed in the feature regions, in order to reduce the computational complexity, the multi resolution strategy of Pyramid is used to calculate the motion vector of the frame; Finally, qualitative and quantitative analysis of the effect of the algorithm is carried out. The results show that the proposed algorithm has better stability compared with image stabilization based on the traditional optical-flow motion vector estimation method.

  15. Motions of the cloud medium behind large scale galactic shocks

    NASA Technical Reports Server (NTRS)

    Yuan, C.; Wang, C. Y.

    1982-01-01

    Mechanisms of decelerating the cloud medium in the large-scale galactic shock are studied. It is shown that the process of cloud-cloud collisions, which results in diffusive momentum transport and hence gives rise to the turbulent viscosity, is very effective in slowing down the cloud medium so that the postshock velocity of the intercloud medium can be matched within a short distance behind the shock front. The drag force exerted by the slow-moving intercloud medium alone is simply not enough to effectively decelerate the cloud medium in the shock. By the use of the results of Shu et al (1972), the internal structure of the shock of the cloud medium is analyzed by including turbulent viscous effects. The thickness of the shock is found to be on the order of 100 pc if the turbulent viscosity is taken proportional to the mean free path of the cloud-cloud collisions. The phase transition takes place in an even thinner layer on the order of 10 pc immediately after the viscous shock front of the intercloud medium.

  16. Low bit rate video coding using robust motion vector regeneration in the decoder.

    PubMed

    Banham, M R; Brailean, J C; Chan, C L; Katsaggelos, A K

    1994-01-01

    In this paper, we present a novel coding technique that makes use of the nonstationary characteristics of an image sequence displacement field to estimate and encode motion information. We utilize an MPEG style codec in which the anchor frames in a sequence are encoded with a hybrid approach using quadtree, DCT, and wavelet-based coding techniques. A quadtree structured approach is also utilized for the interframe information. The main objective of the overall design is to demonstrate the coding potential of a newly developed motion estimator called the coupled linearized MAP (CLMAP) estimator. This estimator can be used as a means for producing motion vectors that may be regenerated at the decoder with a coarsely quantized error term created in the encoder. The motion estimator generates highly accurate motion estimates from this coarsely quantized data. This permits the elimination of a separately coded displaced frame difference (DFD) and coded motion vectors. For low bit rate applications, this is especially important because the overhead associated with the transmission of motion vectors may become prohibitive. We exploit both the advantages of the nonstationary motion estimator and the effective compression of the anchor frame coder to improve the visual quality of reconstructed QCIF format color image sequences at low bit rates. Comparisons are made with other video coding methods, including the H.261 and MPEG standards and a pel-recursive-based codec. PMID:18291958

  17. Description of the barium cloud vectoring systems developed for the PLACES test series

    SciTech Connect

    Finnell, R.T.

    1981-05-01

    The PLACES experiments were conducted to investigate the effects of ionospheric plasmas (created by barium vapor released from rockets) on satellite communications and navigation systems. Launcher setting angles for the rockets were provided by a minicomputer system made up of four subsystems. This report describes the subsystems which determined the barium cloud vectors from TV data alone and from combined radar/TV data.

  18. ACARS wind measurements - An intercomparison with radiosonde, cloud motion and VAS thermally derived winds. [Communications, Addressing and Reporting System VISSR Atmospheric Sounder

    NASA Technical Reports Server (NTRS)

    Lord, R. J.; Menzel, W. P.; Pecht, L. E.

    1984-01-01

    Statistical comparisons between winds measured by ACARS and winds obtained from radiosondes, geostationary satellite image cloud motions, and VAS are presented. Observations from three separate comparisons reveal over 60 percent of wind vector magnitude differences are within 9 m/s, and 70 percent of the directional differences are within 15 deg. The comparisons indicate that the ACARS system provides an independent source of wind data that complements other sources of wind data for constructing composite wind field analyses.

  19. Turbulent fluid motion 2: Scalars, vectors, and tensors

    NASA Technical Reports Server (NTRS)

    Deissler, Robert G.

    1991-01-01

    The author shows that the sum or difference of two vectors is a vector. Similarly the sum of any two tensors of the same order is a tensor of that order. No meaning is attached to the sum of tensors of different orders, say u(sub i) + u(sub ij); that is not a tensor. In general, an equation containing tensors has meaning only if all the terms in the equation are tensors of the same order, and if the same unrepeated subscripts appear in all the terms. These facts will be used in obtaining appropriate equations for fluid turbulence. With the foregoing background, the derivation of appropriate continuum equations for turbulence should be straightforward.

  20. Steady-State Pursuit Is Driven by Object Motion Rather Than the Vector Average of Local Motions

    NASA Technical Reports Server (NTRS)

    Stone, Leland S.; Beutter, B. R.; Lorenceau, J. D.; Ahumada, Al (Technical Monitor)

    1997-01-01

    We have previously shown that humans can pursue the motion of objects whose trajectories can be recovered only by spatio-temporal integration of local motion signals. We now explore the integration rule used to derive the target-motion signal driving pursuit. We measured the pursuit response of 4 observers (2 naive) to the motion of a line-figure diamond viewed through two vertical bar apertures (0.2 cd/square m). The comers were always occluded so that only four line segments (93 cd/square m) were visible behind the occluding foreground (38 cd/square m). The diamond was flattened (40 & 140 degree vertex angles) such that vector averaging of the local normal motions and vertical integration (e.g. IOC) yield very I or different predictions, analogous to using a Type II plaid. The diamond moved along Lissajous-figure trajectories (Ax = Ay = 2 degrees; TFx = 0.8 Hz; TFy = 0.4 Hz). We presented only 1.25 cycles and used 6 different randomly interleaved initial relative phases to minimize the role of predictive strategies. Observers were instructed to track the diamond and reported that its motion was always coherent (unlike type II plaids). Saccade-free portions of the horizontal and vertical eye-position traces sampled at 240 Hz were fit by separate sinusoids. Pursuit gain with respect to the diamond averaged 0.7 across subjects and directions. The ratio of the mean vertical to horizontal amplitude of the pursuit response was 1.7 +/- 0.7 averaged across subjects (1SD). This is close to the prediction of 1.0 from vertical motion-integration rules, but far from 7.7 predicted by vector averaging and infinity predicted by segment- or terminator-tracking strategies. Because there is no retinal motion which directly corresponds to the diamond's motion, steady-state pursuit of our "virtual" diamond is not closed-loop in the traditional sense. Thus, accurate pursuit is unlikely to result simply from local retinal negative feedback. We conclude that the signal driving steady

  1. Arctic PBL Cloud Height and Motion Retrievals from MISR and MINX

    NASA Technical Reports Server (NTRS)

    Wu, Dong L.

    2012-01-01

    How Arctic clouds respond and feedback to sea ice loss is key to understanding of the rapid climate change seen in the polar region. As more open water becomes available in the Arctic Ocean, cold air outbreaks (aka. off-ice flow from polar lows) produce a vast sheet of roll clouds in the planetary boundary layer (PBl). The cold air temperature and wind velocity are the critical parameters to determine and understand the PBl structure formed under these roll clouds. It has been challenging for nadir visible/IR sensors to detect Arctic clouds due to lack of contrast between clouds and snowy/icy surfaces. In addition) PBl temperature inversion creates a further problem for IR sensors to relate cloud top temperature to cloud top height. Here we explore a new method with the Multiangle Imaging Spectro-Radiometer (MISR) instrument to measure cloud height and motion over the Arctic Ocean. Employing a stereoscopic-technique, MISR is able to measure cloud top height accurately and distinguish between clouds and snowy/icy surfaces with the measured height. We will use the MISR INteractive eXplorer (MINX) to quantify roll cloud dynamics during cold-air outbreak events and characterize PBl structures over water and over sea ice.

  2. Insitu aircraft verification of the quality of satellite cloud winds over oceanic regions

    NASA Technical Reports Server (NTRS)

    Hasler, A. F.; Skillman, W. C.

    1979-01-01

    A five year aircraft experiment to verify the quality of satellite cloud winds over oceans using in situ aircraft inertial navigation system wind measurements is presented. The final results show that satellite measured cumulus cloud motions are very good estimators of the cloud base wind for trade wind and subtropical high regions. The average magnitude of the vector differences between the cloud motion and the cloud base wind is given. For cumulus clouds near frontal regions, the cloud motion agreed best with the mean cloud layer wind. For a very limited sample, cirrus cloud motions also most closely followed the mean wind in the cloud layer.

  3. Object detection and tracking with active camera on motion vectors of feature points and particle filter.

    PubMed

    Chen, Yong; Zhang, Rong-Hua; Shang, Lei; Hu, Eric

    2013-06-01

    A method based on motion vectors of feature points and particle filter has been proposed and developed for an active∕moving camera for object detection and tracking purposes. The object is detected by histogram of motion vectors first, and then, on the basis of particle filter algorithm, the weighing factors are obtained via color information. In addition, re-sampling strategy and surf feature points are used to remedy the drawback of particle degeneration. Experimental results demonstrate the practicability and accuracy of the new method and are presented in the paper. PMID:23822380

  4. Convective and moist vorticity vectors associated with tropical oceanic convection: A three-dimensional cloud-resolving model simulation

    NASA Astrophysics Data System (ADS)

    Gao, Shouting; Li, Xiaofan; Tao, Wei-Kuo; Shie, Chung-Lin; Lang, Steve

    2007-01-01

    The relationships between cloud hydrometeors and convective/moist vorticity vectors are investigated using hourly data from a three-dimensional, 5-day cloud-resolving model (CRM) simulation during the Tropical Rainfall Measuring Mission (TRMM) Kwajalein Experiment (KWAJEX). Vertical components of convective and moist vorticity vectors are highly correlated with cloud hydrometeors. The vertical components represent the interaction between horizontal vorticity and horizontal moist potential temperature/specific humidity gradient. The vertical components of convective and moist vorticity vectors can be used to study tropical oceanic convection in both two-dimensional and three-dimensional frameworks.

  5. Suggested Courseware for the Non-Calculus Physics Student: Measurement, Vectors, and One-Dimensional Motion.

    ERIC Educational Resources Information Center

    Mahoney, Joyce; And Others

    1988-01-01

    Evaluates 16 commercially available courseware packages covering topics for introductory physics. Discusses the price, sub-topics, program type, interaction, time, calculus required, graphics, and comments of each program. Recommends two packages in measurement and vectors, and one-dimensional motion respectively. (YP)

  6. Secondary School Mathematics, Chapter 21, Rigid Motions and Vectors, Chapter 22, Computers and Programs. Student's Text.

    ERIC Educational Resources Information Center

    Stanford Univ., CA. School Mathematics Study Group.

    Transformation geometry topics are covered in one chapter of Unit 11 of this SMSG series. Work with translations, reflections, rotations, and composition of motions is included; vectors are briefly discussed. The chapter on computers and programming deals with recent history and uses of of the computer, organization of a digital computer, an…

  7. Secondary School Mathematics, Chapter 21, Rigid Motions and Vectors, Chapter 22, Computer and Programs. Teacher's Commentary.

    ERIC Educational Resources Information Center

    Stanford Univ., CA. School Mathematics Study Group.

    The teacher's guide for the eleventh unit in this SMSG series covers the chapter on rigid motions and vectors and the chapter on computers and programs. The overall purpose for each of the chapters is described, the prerequisite knowledge needed by students is specified, the mathematical development of each chapter is detailed, behavioral…

  8. Motion data classification on the basis of dynamic time warping with a cloud point distance measure

    NASA Astrophysics Data System (ADS)

    Switonski, Adam; Josinski, Henryk; Zghidi, Hafedh; Wojciechowski, Konrad

    2016-06-01

    The paper deals with the problem of classification of model free motion data. The nearest neighbors classifier which is based on comparison performed by Dynamic Time Warping transform with cloud point distance measure is proposed. The classification utilizes both specific gait features reflected by a movements of subsequent skeleton joints and anthropometric data. To validate proposed approach human gait identification challenge problem is taken into consideration. The motion capture database containing data of 30 different humans collected in Human Motion Laboratory of Polish-Japanese Academy of Information Technology is used. The achieved results are satisfactory, the obtained accuracy of human recognition exceeds 90%. What is more, the applied cloud point distance measure does not depend on calibration process of motion capture system which results in reliable validation.

  9. Interactions between spacecraft motions and the atmospheric cloud physics laboratory experiments

    NASA Technical Reports Server (NTRS)

    Anderson, B. J.

    1981-01-01

    In evaluating the effects of spacecraft motions on atmospheric cloud physics laboratory (ACPL) experimentation, the motions of concern are those which will result in the movement of the fluid or cloud particles within the experiment chambers. Of the various vehicle motions and residual forces which can and will occur, three types appear most likely to damage the experimental results: non-steady rotations through a large angle, long-duration accelerations in a constant direction, and vibrations. During the ACPL ice crystal growth experiments, the crystals are suspended near the end of a long fiber (20 cm long by 200 micron diameter) of glass or similar material. Small vibrations of the supported end of the fiber could cause extensive motions of the ice crystal, if care is not taken to avoid this problem.

  10. Water vapor motion signal extraction from FY-2E longwave infrared window images for cloud-free regions: The temporal difference technique

    NASA Astrophysics Data System (ADS)

    Yang, Lu; Wang, Zhenhui; Chu, Yanli; Zhao, Hang; Tang, Min

    2014-11-01

    The aim of this study is to calculate the low-level atmospheric motion vectors (AMVs) in clear areas with FY-2E IR2 window (11.59-12.79 μm) channel imagery, where the traditional cloud motion wind technique fails. A new tracer selection procedure, which we call the temporal difference technique, is demonstrated in this paper. This technique makes it possible to infer low-level wind by tracking features in the moisture pattern that appear as brightness temperature ( T B) differences between consecutive sequences of 30-min-interval FY-2E IR2 images over cloud-free regions. The T B difference corresponding to a 10% change in water vapor density is computed with the Moderate Resolution Atmospheric Transmission (MODTRAN4) radiative transfer model. The total contribution from each of the 10 layers is analyzed under four typical atmospheric conditions: tropical, midlatitude summer, U.S. standard, and midlatitude winter. The peak level of the water vapor weighting function for the four typical atmospheres is assigned as a specific height to the T B "wind". This technique is valid over cloud-free ocean areas. The proposed algorithm exhibits encouraging statistical results in terms of vector difference (VD), speed bias (BIAS), mean vector difference (MVD), standard deviation (SD), and root-mean-square error (RMSE), when compared with the wind field of NCEP reanalysis data and rawinsonde observations.

  11. A Convective Vorticity Vector Associated With Tropical Convection: A 2D Cloud-Resolving Modeling Study

    NASA Technical Reports Server (NTRS)

    Gao, Shou-Ting; Ping, Fan; Li, Xiao-Fan; Tao, Wei-Kuo

    2004-01-01

    Although dry/moist potential vorticity is a useful physical quantity for meteorological analysis, it cannot be applied to the analysis of 2D simulations. A convective vorticity vector (CVV) is introduced in this study to analyze 2D cloud-resolving simulation data associated with 2D tropical convection. The cloud model is forced by the vertical velocity, zonal wind, horizontal advection, and sea surface temperature obtained from the TOGA COARE, and is integrated for a selected 10-day period. The CVV has zonal and vertical components in the 2D x-z frame. Analysis of zonally-averaged and mass-integrated quantities shows that the correlation coefficient between the vertical component of the CVV and the sum of the cloud hydrometeor mixing ratios is 0.81, whereas the correlation coefficient between the zonal component and the sum of the mixing ratios is only 0.18. This indicates that the vertical component of the CVV is closely associated with tropical convection. The tendency equation for the vertical component of the CVV is derived and the zonally-averaged and mass-integrated tendency budgets are analyzed. The tendency of the vertical component of the CVV is determined by the interaction between the vorticity and the zonal gradient of cloud heating. The results demonstrate that the vertical component of the CVV is a cloud-linked parameter and can be used to study tropical convection.

  12. Multiangle Remote Sensing of Optically Thin Cirrus Clouds From MISR Using Support Vector Machines

    NASA Astrophysics Data System (ADS)

    Garay, M. J.; Mazzoni, D.; Davies, R.; Wagstaff, K.

    2004-05-01

    Thin cirrus clouds, those with optical depths less than 1, can potentially have large radiative effects on the atmospheric and surface energy budgets in regions where they are prevalent. They also present an impediment to the retrieval of clear sky properties such as aerosol optical depth, temperature profiles, etc. Such clouds, however, are notoriously difficult to detect using standard satellite remote sensing techniques. The unique multiangle sensing capability of the Multiangle Imaging SpectroRadiometer (MISR) on NASA's Terra satellite, in particular the availability of cameras with view angles as large as 70.5 degrees, gives MISR the ability to detect thin cirrus clouds that are invisible to nadir-looking instruments. While MISR has been operational for over four years and many scenes containing thin cirrus have been examined on a per case basis, there remains a need to objectively and automatically identify just the cirrus clouds within any given scene. Based on our previous work applying machine learning technology to develop a more robust MISR cloud mask, we have developed a thin cirrus cloud detector for MISR, using Support Vector Machines (SVMs), and taking advantage of spectral, spatial and angular signature information from MISR's 45.6, 60 and 70.5-degree cameras. For a few representative cases, we will demonstrate the accuracy of the SVM cirrus retrieval, especially in comparison to a traditional nadir-looking retrieval, emphasizing the usefulness of the multiangle approach. We then show how this trained SVM can be used to generate a climatology of thin cirrus clouds.

  13. Proper motion of the Large Magellanic Cloud and the mass of the galaxy. 1: Observational results

    NASA Astrophysics Data System (ADS)

    Jones, B. F.; Klemola, A. R.; Lin, D. N. C.

    1994-04-01

    We have measured the proper motion of the Large Magellanic Cloud (LMC) using 21 plates taken with the Cerro-Tololo Inter-American Observatory (CTIO) 4 m telescope and covering an epoch span of 14 yr. The plates were centered on the globular cluster NGC 2257, lying on the northeast periphery of the Cloud. Proper motions were determined for 251 LMC members, chosen on the basis of the photometry of Stryker (1984), using 92 galaxies as a reference frame. The measured mean absolute proper motion of the LMC stars in our region is mualpha = 0.120 sec +/- 0.028 sec century-1, mudelta=0.026 sec +/- 0.027 sec century-1. After correcting for the rotation of the LMC and the effects of solar motion, this proper motion combined with the radial velocity of the LMC implies a galactocentric coordinate radial velocity for the Cloud of 48 +/- 41 km s-1 and a total galactocentric transverse velocity of 215 +/- 48 km s-1.

  14. Effect of the Drag Force on the Orbital Motion of the Broad-line Region Clouds

    NASA Astrophysics Data System (ADS)

    Khajenabi, Fazeleh

    2016-09-01

    We investigate the orbital motion of cold clouds in the broad-line region of active galactic nuclei subject to the gravity of a black hole, a force due to a non-isotropic central source, and a drag force proportional to the velocity square. The intercloud is described using the standard solutions for the advection-dominated accretion flows. The orbit of a cloud decays because of the drag force, but the typical timescale of clouds falling onto the central black hole is shorter compared to the linear drag case. This timescale is calculated when a cloud moves through a static or rotating intercloud. We show that when the drag force is a quadratic function of the velocity, irrespective of the initial conditions and other input parameters, clouds will generally fall onto the central region much faster than the age of whole system, and since cold clouds present in most of the broad-line regions, we suggest that mechanisms for the continuous creation of the clouds must operate in these systems.

  15. Motion Vector Field Estimation Using Brightness Constancy Assumption and Epipolar Geometry Constraint

    NASA Astrophysics Data System (ADS)

    Hosseinyalamdary, S.; Yilmaz, A.

    2014-11-01

    In most Photogrammetry and computer vision tasks, finding the corresponding points among images is required. Among many, the Lucas-Kanade optical flow estimation has been employed for tracking interest points as well as motion vector field estimation. This paper uses the IMU measurements to reconstruct the epipolar geometry and it integrates the epipolar geometry constraint with the brightness constancy assumption in the Lucas-Kanade method. The proposed method has been tested using the KITTI dataset. The results show the improvement in motion vector field estimation in comparison to the Lucas-Kanade optical flow estimation. The same approach has been used in the KLT tracker and it has been shown that using epipolar geometry constraint can improve the KLT tracker. It is recommended that the epipolar geometry constraint is used in advanced variational optical flow estimation methods.

  16. Cloud field classification based upon high spatial resolution textural features. II - Simplified vector approaches

    NASA Technical Reports Server (NTRS)

    Chen, D. W.; Sengupta, S. K.; Welch, R. M.

    1989-01-01

    This paper compares the results of cloud-field classification derived from two simplified vector approaches, the Sum and Difference Histogram (SADH) and the Gray Level Difference Vector (GLDV), with the results produced by the Gray Level Cooccurrence Matrix (GLCM) approach described by Welch et al. (1988). It is shown that the SADH method produces accuracies equivalent to those obtained using the GLCM method, while the GLDV method fails to resolve error clusters. Compared to the GLCM method, the SADH method leads to a 31 percent saving in run time and a 50 percent saving in storage requirements, while the GLVD approach leads to a 40 percent saving in run time and an 87 percent saving in storage requirements.

  17. Intraseasonal behavior of clouds, temperature, and motion in the tropics

    NASA Technical Reports Server (NTRS)

    Salby, Murry L.; Hendon, Harry H.

    1994-01-01

    The spectral character of tropical convection is investigated in an 11-yr record of outgoing longwave radiation from the Advanced Very High Resolution Radiometer (AVHRR) to identify interaction with the tropical circulation. Along the equator in the eastern hemisphere, the space-time spectrum of convection possesses a broad peak at wavenumbers 1-3 and eastward periods of 35-95 days. Significantly broader than the dynamical signal of the Madden-Julian oscillation (MJO), this quasi-discrete convective signal is associatd with a large-scale anomaly that propagates across and modulates time mean or 'climatological convection' over the equatorial Indian Ocean and western Pacific. Outside that region the convective signal is small, even though, under amplified conditions, coherence can be found east of the date line and in the subtropics. Having a zonal scale of approximately wavenumber 2, anomalous convection propagates eastward at some 5 m/s and suppresses as well as reinforces climatological in the eastern hemisphere. The convective signal amplifies to a seasonal maximum near vernal equinox and, to a weaker degree, again near autumnal equinox, when climatological convection and warm sea surface temperature (SST) cross the equator. Contemporaneous records of motion from European Center for medium-Range Weather Forecasts (ECMWF) analyses and tropospheric-mean temperature from Microwave Sounding Unit reveal an anomalous component of the tropical circulation that coexists with the convective signal and embodies many of the established properties of the MJO. In the eastern hemisphere, subtropical Rossby gyres and zonal Kelvin structure along the equator flank the convective anomaly as it tracks eastward, giving the anomalous circulation to form of a 'forced response.' In the western hemisphere, the dynamical signal is composed chiefly of wavenumber-1 Kelvin structure, which as the form of a 'propagating response' that is excited in and radiates away from anomalous

  18. Transverse motion of high-speed barium clouds in the ionosphere

    NASA Technical Reports Server (NTRS)

    Mitchell, H. G., Jr.; Fedder, J. A.; Huba, J. D.; Zalesak, S. T.

    1985-01-01

    Simulation results, based on a field-line-integrated, two-dimensional, electrostatic model, are presented for the motion of a barium cloud injected transverse to the geomagnetic field in the ionosphere at high speeds. It is found that the gross evaluation of injected plasma clouds depends on the initial conditions, as well as the nature of the background coupling. For a massive (mass of about 10 kg), orbital (velocity of about 5 km/s) release in the F region (350-450 km), it is found that plasma clouds can drift tens of kilometers across the magnetic field in tens of seconds after ionization. This type of release is similar to those which are planned for the Combined Release and Radiation Effects Satellite mission.

  19. Characterizing uncertainty in the motion, future location and ash concentrations of volcanic plumes and ash clouds

    NASA Astrophysics Data System (ADS)

    Webley, P.; Patra, A. K.; Bursik, M. I.; Pitman, E. B.; Dehn, J.; Singh, T.; Singla, P.; Stefanescu, E. R.; Madankan, R.; Pouget, S.; Jones, M.; Morton, D.; Pavolonis, M. J.

    2013-12-01

    Forecasting the location and airborne concentrations of volcanic ash plumes and their dispersing clouds is complex and knowledge of the uncertainty in these forecasts is critical to assess and mitigate the hazards that could exist. We show the results from an interdisciplinary project that brings together scientists drawn from the atmospheric sciences, computer science, engineering, mathematics, and geology. The project provides a novel integration of computational and statistical modeling with a widely-used volcanic particle dispersion code, to provide quantitative measures of confidence in predictions of the motion of ash clouds caused by volcanic eruptions. We combine high performance computing and stochastic analysis, resulting in real time predictions of ash cloud motion that account for varying wind conditions and a range of model variables. We show how coupling a real-time model for ash dispersal, PUFF, with a volcanic eruption model, BENT, allows for the definition of the variability in the dispersal model inputs and hence classify the uncertainty that can then propagate for the ash cloud location and downwind concentrations. We additionally analyze the uncertainty in the numerical weather prediction forecast data used by the dispersal model by using ensemble forecasts and assess how this affects the downwind concentrations. These are all coupled together and by combining polynomical chaos quadrature with stochastic integration techniques, we provide a quantitative measure of the reliability (i.e. error) of those predictions. We show comparisons of the downwind height calculations and mass loadings with observations of ash clouds available from satellite remote sensing data. The aim is to provide a probabilistic forecast of location and ash concentration that can be generated in real-time and used by those end users in the operational ash cloud hazard assessment environment.

  20. Measuring the proper motions of the Large and Small Magellanic Clouds

    NASA Astrophysics Data System (ADS)

    Ellingsen, Simon; Macquart, Jean-Pierre; Bignall, Hayley; Breen, Shari; Reynolds, Cormac; Imai, Hiroshi; Keller, Stefan; Bekki, Kenji; Krishnan, Vasaant; Cioni, Maria-Rosa

    2013-10-01

    Interactions between galaxies are known to play a key role in their evolution throughout cosmic history. Studies of past and current interactions between Local Group galaxies provide us with a unique opportunity to investigate the key factors and effects of such interactions at high resolution and sensitivity. Our understanding of the interaction of the Large and Small Magellanic Clouds (LMC & SMC) with each other and with the Milky Way (MW) have changed dramatically in the last decade due to the determination of the proper motions of the LMC and SMC from optical studies. The derived proper motions predict a history of interaction for the Clouds that is at odds with the leading and trailing arms of Magellanic Stream gas. This proposal is a companion to an LBA project to measure the proper motions of both the Large and Small Magellanic Clouds. Observations to measure the flux density of the potential maser targets a few weeks prior to an LBA observation will enable us to tailor the observing strategy to maximise the observational sensitivity and hence the astrometric accuracy.

  1. Measuring the proper motions of the Large and Small Magellanic Clouds

    NASA Astrophysics Data System (ADS)

    Ellingsen, Simon; Macquart, Jean-Pierre; Bignall, Hayley; Breen, Shari; Reynolds, Cormac; Imai, Hiroshi; Keller, Stefan; Bekki, Kenji; Krishnan, Vasaant; Cioni, Maria-Rosa

    2013-04-01

    Interactions between galaxies are known to play a key role in their evolution throughout cosmic history. Studies of past and current interactions between Local Group galaxies provide us with a unique opportunity to investigate the key factors and effects of such interactions at high resolution and sensitivity. Our understanding of the interaction of the Large and Small Magellanic Clouds (LMC & SMC) with each other and with the Milky Way (MW) have changed dramatically in the last decade due to the determination of the proper motions of the LMC and SMC from optical studies. The derived proper motions predict a history of interaction for the Clouds that is at odds with the leading and trailing arms of Magellanic Stream gas. This proposal is a companion to an LBA project to measure the proper motions of both the Large and Small Magellanic Clouds. Observations to measure the flux density of the potential maser targets a few weeks prior to an LBA observation will enable us to tailor the observing strategy to maximise the observational sensitivity and hence the astrometric accuracy.

  2. Measuring the proper motions of the Large and Small Magellanic Clouds

    NASA Astrophysics Data System (ADS)

    Ellingsen, Simon; Macquart, Jean-Pierre; Bignall, Hayley; Beasley, Tony; Breen, Shari; Reynolds, Cormac; Imai, Hiroshi; Keller, Stefan; Bekki, Kenji; Krishnan, Vasaant; Cioni, Maria-Rosa

    2014-04-01

    Interactions between galaxies are known to play a key role in their evolution throughout cosmic history. Studies of past and current interactions between Local Group galaxies provide us with a unique opportunity to investigate the key factors and effects of such interactions at high resolution and sensitivity. Our understanding of the interaction of the Large and Small Magellanic Clouds (LMC & SMC) with each other and with the Milky Way (MW) have changed dramatically in the last decade due to the determination of the proper motions of the LMC and SMC from optical studies. The derived proper motions predict a history of interaction for the Clouds that is at odds with the leading and trailing arms of Magellanic Stream gas. This proposal is a companion to an LBA project to measure the proper motions of both the Large and Small Magellanic Clouds. Observations to measure the flux density of the potential maser targets a few weeks prior to an LBA observation will enable us to tailor the observing strategy to maximise the observational sensitivity and hence the astrometric accuracy.

  3. Statistical motion vector analysis for object tracking in compressed video streams

    NASA Astrophysics Data System (ADS)

    Leny, Marc; Prêteux, Françoise; Nicholson, Didier

    2008-02-01

    Compressed video is the digital raw material provided by video-surveillance systems and used for archiving and indexing purposes. Multimedia standards have therefore a direct impact on such systems. If MPEG-2 used to be the coding standard, MPEG-4 (part 2) has now replaced it in most installations, and MPEG-4 AVC/H.264 solutions are now being released. Finely analysing the complex and rich MPEG-4 streams is a challenging issue addressed in that paper. The system we designed is based on five modules: low-resolution decoder, motion estimation generator, object motion filtering, low-resolution object segmentation, and cooperative decision. Our contributions refer to as the statistical analysis of the spatial distribution of the motion vectors, the computation of DCT-based confidence maps, the automatic motion activity detection in the compressed file and a rough indexation by dedicated descriptors. The robustness and accuracy of the system are evaluated on a large corpus (hundreds of hours of in-and outdoor videos with pedestrians and vehicles). The objective benchmarking of the performances is achieved with respect to five metrics allowing to estimate the error part due to each module and for different implementations. This evaluation establishes that our system analyses up to 200 frames (720x288) per second (2.66 GHz CPU).

  4. Motion-vector-based adaptive quantization in MPEG-4 fine granular scalable coding

    NASA Astrophysics Data System (ADS)

    Yang, Shuping; Lin, Xinggang; Wang, Guijin

    2003-05-01

    Selective enhancement mechanism of Fine-Granular-Scalability (FGS) In MPEG-4 is able to enhance specific objects under bandwidth variation. A novel technique for self-adaptive enhancement of interested regions based on Motion Vectors (MVs) of the base layer is proposed, which is suitable for those video sequences having still background and what we are interested in is only the moving objects in the scene, such as news broadcasting, video surveillance, Internet education, etc. Motion vectors generated during base layer encoding are obtained and analyzed. A Gaussian model is introduced to describe non-moving macroblocks which may have non-zero MVs caused by random noise or luminance variation. MVs of these macroblocks are set to zero to prevent them from being enhanced. A segmentation algorithm, region growth, based on MV values is exploited to separate foreground from background. Post-process is needed to reduce the influence of burst noise so that only the interested moving regions are left. Applying the result in selective enhancement during enhancement layer encoding can significantly improves the visual quality of interested regions within an aforementioned video transmitted at different bit-rate in our experiments.

  5. Pacific-North American plate motion from very long baseline interferometry compared with motion inferred from magnetic anomalies, transform faults, and earthquake slip vectors

    NASA Technical Reports Server (NTRS)

    Argus, Donald F.; Gordon, Richard G.

    1990-01-01

    Geodetic VLBI measurements were used to test whether the Pacific-North American plate velocity averaged over several years of direct observation (1984-1987) equals that averaged over millions of years. It was also tested whether this velocity parallels the San Andreas fault, transform faults and earthquake slip vectors in the Gulf of California, and earthquake slip vectors along the Queen Charlotte fault, along the Alaskan peninsula, and along the Kamchatkan peninsula. The VLBI data provide an estimate of the direction of plate motion that is independent of estimates from fault azimuths and earthquake slip vectors. The Euler vector determined from VLBI was found to be nearly identical to the Euler vector of plate motion model NUVEL-1, which is based on the trends of transform faults, earthquake slip vectors, and spreading rates from marine magnetic anomalies that average motion since 3 Ma. The velocity between the Pacific and North American plates averaged over the past several years equals or nearly equals its velocity averaged over the past several million years, the difference along their boundary nowhere exceeding 4 + or - 7 mm/yr.

  6. A comparison of cloud motion winds from ATS 6 images with coinciding SMS 1 winds

    NASA Technical Reports Server (NTRS)

    Kuhlow, W. W.; Chatters, G. C.

    1978-01-01

    A methodology is developed for accurate measurement of cloud motion winds from the geosynchronous ATS 6 image data. Attitude changes between consecutive images (as a function of scan-line number) are accounted for in wind computations through measurement of the earth-edge displacements between the successive infrared images. Also, an image matching procedure is used to remove obvious and distracting image distortions. The availability of SMS imagery coinciding with ATS 6 imagery makes SMS an excellent reference against which the quality of ATS 6 winds can be tested. The resulting winds inferred from cloud displacement measurements taken from a sequence of the corrected images are found to agree better than 2 m/sec rms with winds measured from coincident SMS 1 imagery.

  7. A comparison of cloud motion and ship wind observations over the Indian Ocean for the year of FGGE

    NASA Astrophysics Data System (ADS)

    Wylie, Donald P.; Hinton, Barry B.

    1982-06-01

    Cloud motions over the Indian Ocean were compared to ship observations for the FGGE year. The statistics of this comparison show seasonal changes in the cloud-ship relationship as well as geographical and wind-pattern-dependent fetch history changes. Most of these changes follow simple boundary-layer relationships governed by friction and temperature advection. The most significant result is the improvement of the cloud-ship directional shear with wind speed. The mean veering angle between cloud and ship measurements decreased at higher wind speeds along with scatter of the shearing angle. This implies that the ability of cloud motion measurements to indicate the wind stress on the ocean improves for the important situations when the winds are strong.

  8. The primer vector in linear, relative-motion equations. [spacecraft trajectory optimization

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Primer vector theory is used in analyzing a set of linear, relative-motion equations - the Clohessy-Wiltshire equations - to determine the criteria and necessary conditions for an optimal, N-impulse trajectory. Since the state vector for these equations is defined in terms of a linear system of ordinary differential equations, all fundamental relations defining the solution of the state and costate equations, and the necessary conditions for optimality, can be expressed in terms of elementary functions. The analysis develops the analytical criteria for improving a solution by (1) moving any dependent or independent variable in the initial and/or final orbit, and (2) adding intermediate impulses. If these criteria are violated, the theory establishes a sufficient number of analytical equations. The subsequent satisfaction of these equations will result in the optimal position vectors and times of an N-impulse trajectory. The solution is examined for the specific boundary conditions of (1) fixed-end conditions, two-impulse, and time-open transfer; (2) an orbit-to-orbit transfer; and (3) a generalized rendezvous problem. A sequence of rendezvous problems is solved to illustrate the analysis and the computational procedure.

  9. Automated cloud tracking using precisely aligned digital ATS pictures.

    NASA Technical Reports Server (NTRS)

    Smith, E. A.; Phillips, D. R.

    1972-01-01

    Discussion of the interactive man-computer system (WIMDCO) for measuring cloud motion from ATS pictures. The multipicture model of ATS navigation is used for consecutive ATS digital picture alignment to provide the required precision in cloud motion measurements by automated tracking techniques. Cloud motion is measured by tracking clouds between two digital pictures with the aid of two-dimensional cross correlation analysis. The fast Fourier transform method and other programming techniques are used for time and cost minimization. Cloud motion vectors were computed over three time intervals in July, 1969. The EW and NS components were reproducible within roughly 2 knots.

  10. Apsidal motions of 90 eccentric binary systems in the Small Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Hong, Kyeongsoo; Lee, Jae Woo; Kim, Seung-Lee; Koo, Jae-Rim; Lee, Chung-UK

    2016-07-01

    We examined light curves of 1138 stars brighter than 18.0 mag in the I band and less than a mean magnitude error of 0.1 mag in the V band from the Optical Gravitational Lensing Experiment (OGLE)-III eclipsing binary catalogue, and found 90 new binary systems exhibiting apsidal motion. In this study, the samples of apsidal motion stars in the Small Magellanic Cloud (SMC) were increased by a factor of about 3.0 than previously known. In order to determine the period of the apsidal motion for the binaries, we analysed in detail both the light curves and eclipse timings using the MACHO (MAssive Compact Halo Objects) and OGLE photometric data base. For the eclipse timing diagrams of the systems, new times of minimum light were derived from the full light curve combined at intervals of one year from the survey data. The new 90 binaries have apsidal motion periods in the range of 12-897 yr. An additional short-term oscillation was detected in four systems (OGLE-SMC-ECL-1634, 1947, 3035, and 4946), which most likely arises from the existence of a third body orbiting each eclipsing binary. Since the systems presented here are based on homogeneous data and have been analysed in the same way, they are suitable for further statistical analysis.

  11. Closed-form solutions for estimating a rigid motion from plane correspondences extracted from point clouds

    NASA Astrophysics Data System (ADS)

    Khoshelham, Kourosh

    2016-04-01

    Registration is often a prerequisite step in processing point clouds. While planar surfaces are suitable features for registration, most of the existing plane-based registration methods rely on iterative solutions for the estimation of transformation parameters from plane correspondences. This paper presents a new closed-form solution for the estimation of a rigid motion from a set of point-plane correspondences. The role of normalization is investigated and its importance for accurate plane fitting and plane-based registration is shown. The paper also presents a thorough evaluation of the closed-form solutions and compares their performance with the iterative solution in terms of accuracy, robustness, stability and efficiency. The results suggest that the closed-form solution based on point-plane correspondences should be the method of choice in point cloud registration as it is significantly faster than the iterative solution, and performs as well as or better than the iterative solution in most situations. The normalization of the point coordinates is also recommended as an essential preprocessing step for point cloud registration. An implementation of the closed-form solutions in MATLAB is available at: http://people.eng.unimelb.edu.au/kkhoshelham/research.html#directmotion

  12. A vector-dyadic development of the equations of motion for N-coupled rigid bodies and point masses

    NASA Technical Reports Server (NTRS)

    Frisch, H. P.

    1974-01-01

    The equations of motion are derived, in vector-dyadic format, for a topological tree of coupled rigid bodies, point masses, and symmetrical momentum wheels. These equations were programmed, and form the basis for the general-purpose digital computer program N-BOD. A complete derivation of the equations of motion is included along with a description of the methods used for kinematics, constraint elimination, and for the inclusion of nongyroscope forces and torques acting external or internal to the system.

  13. Cloud shadow speed sensor

    NASA Astrophysics Data System (ADS)

    Fung, V.; Bosch, J. L.; Roberts, S. W.; Kleissl, J.

    2014-06-01

    Changing cloud cover is a major source of solar radiation variability and poses challenges for the integration of solar energy. A compact and economical system is presented that measures cloud shadow motion vectors to estimate power plant ramp rates and provide short-term solar irradiance forecasts. The cloud shadow speed sensor (CSS) is constructed using an array of luminance sensors and a high-speed data acquisition system to resolve the progression of cloud passages across the sensor footprint. An embedded microcontroller acquires the sensor data and uses a cross-correlation algorithm to determine cloud shadow motion vectors. The CSS was validated against an artificial shading test apparatus, an alternative method of cloud motion detection from ground-measured irradiance (linear cloud edge, LCE), and a UC San Diego sky imager (USI). The CSS detected artificial shadow directions and speeds to within 15° and 6% accuracy, respectively. The CSS detected (real) cloud shadow directions and speeds with average weighted root-mean-square difference of 22° and 1.9 m s-1 when compared to USI and 33° and 1.5 m s-1 when compared to LCE results.

  14. Cloud speed sensor

    NASA Astrophysics Data System (ADS)

    Fung, V.; Bosch, J. L.; Roberts, S. W.; Kleissl, J.

    2013-10-01

    Changing cloud cover is a major source of solar radiation variability and poses challenges for the integration of solar energy. A compact and economical system that measures cloud motion vectors to estimate power plant ramp rates and provide short term solar irradiance forecasts is presented. The Cloud Speed Sensor (CSS) is constructed using an array of luminance sensors and high-speed data acquisition to resolve the progression of cloud passages across the sensor footprint. An embedded microcontroller acquires the sensor data and uses a cross-correlation algorithm to determine cloud motion vectors. The CSS was validated against an artificial shading test apparatus, an alternative method of cloud motion detection from ground measured irradiance (Linear Cloud Edge, LCE), and a UC San Diego Sky Imager (USI). The CSS detected artificial shadow directions and speeds to within 15 and 6% accuracy, respectively. The CSS detected (real) cloud directions and speeds without average bias and with average weighted root mean square difference of 22° and 1.9 m s-1 when compared to USI and 33° and 1.5 m s-1 when compared to LCE results.

  15. Atmospheric Motion Vectors from INSAT-3D: Initial quality assessment and its impact on track forecast of cyclonic storm NANAUK

    NASA Astrophysics Data System (ADS)

    Deb, S. K.; Kishtawal, C. M.; Kumar, Prashant; Kiran Kumar, A. S.; Pal, P. K.; Kaushik, Nitesh; Sangar, Ghansham

    2016-03-01

    The advanced Indian meteorological geostationary satellite INSAT-3D was launched on 26 July 2013 with an improved imager and an infrared sounder and is placed at 82°E over the Indian Ocean region. With the advancement in retrieval techniques of different atmospheric parameters and with improved imager data have enhanced the scope for better understanding of the different tropical atmospheric processes over this region. The retrieval techniques and accuracy of one such parameter, Atmospheric Motion Vectors (AMV) has improved significantly with the availability of improved spatial resolution data along with more options of spectral channels in the INSAT-3D imager. The present work is mainly focused on providing brief descriptions of INSAT-3D data and AMV derivation processes using these data. It also discussed the initial quality assessment of INSAT-3D AMVs for a period of six months starting from 01 February 2014 to 31 July 2014 with other independent observations: i) Meteosat-7 AMVs available over this region, ii) in-situ radiosonde wind measurements, iii) cloud tracked winds from Multi-angle Imaging Spectro-Radiometer (MISR) and iv) numerical model analysis. It is observed from this study that the qualities of newly derived INSAT-3D AMVs are comparable with existing two versions of Meteosat-7 AMVs over this region. To demonstrate its initial application, INSAT-3D AMVs are assimilated in the Weather Research and Forecasting (WRF) model and it is found that the assimilation of newly derived AMVs has helped in reduction of track forecast errors of the recent cyclonic storm NANAUK over the Arabian Sea. Though, the present study is limited to its application to one case study, however, it will provide some guidance to the operational agencies for implementation of this new AMV dataset for future applications in the Numerical Weather Prediction (NWP) over the south Asia region.

  16. Motion of the angular momentum vector in body coordinates for torque-free dual-spin spacecraft

    NASA Technical Reports Server (NTRS)

    Fedor, J. V.

    1981-01-01

    The motion of the angular momentum vector in body coordinates for torque free, asymmetric dual spin spacecraft without and, for a special case, with energy dissipation on the main spacecraft is investigated. Without energy dissipation, two integrals can be obtained from the Euler equations of motion. Using the classical method of elimination of variable, the motion about the equilibrium points (six for the general case) are derived with these integrals. For small nutation angle, theta, the trajectories about the theta = 0 deg and theta = 180 deg points readily show the requirements for stable motion about these points. Also the conditions needed to eliminate stable motion about the theta = 180 deg point as well as the other undesireable equilibrium points follow directly from these equations. For the special case where the angular momentum vector moves about the principal axis which contains the momentum wheel, the notion of 'free variable' azimuth angle is used. Physically this angle must vary from 0 to 2 pi in a circular periodic fashion. Expressions are thus obtained for the nutation angle in terms of the free variable and other spacecraft parameters. Results show that in general there are two separate trajectory expressions that govern the motion of the angular momentum vector in body coordinates.

  17. Maxwell perturbations on Kerr-anti-de Sitter black holes: Quasinormal modes, superradiant instabilities, and vector clouds

    NASA Astrophysics Data System (ADS)

    Wang, Mengjie; Herdeiro, Carlos

    2016-03-01

    Scalar and gravitational perturbations on Kerr-anti-de Sitter (Kerr-AdS) black holes have been addressed in the literature and have been shown to exhibit a rich phenomenology. In this paper, we complete the analysis of bosonic fields on this background by studying Maxwell perturbations, focusing on superradiant instabilities and vector clouds. For this purpose, we solve the Teukolsky equations numerically, imposing the boundary conditions we have proposed in [1] for the radial Teukolsky equation. As found therein, two Robin boundary conditions can be imposed for Maxwell fields on Kerr-AdS black holes, one of which produces a new set of quasinormal modes even for Schwarzschild-AdS black holes. Here, we show these different boundary conditions produce two different sets of superradiant modes. Interestingly, the "new modes" may be unstable in a larger parameter space. We then study stationary Maxwell clouds that exist at the threshold of the superradiant instability, with the two Robin boundary conditions. These clouds, obtained at the linear level, indicate the existence of a new family of black hole solutions at the nonlinear level, within the Einstein-Maxwell-AdS system, branching off from the Kerr-Newman-AdS family. As a comparison with the Maxwell clouds, scalar clouds on Kerr-AdS black holes are also studied, and it is shown there are Kerr-AdS black holes that are stable against scalar, but not vector, modes with the same "quantum numbers".

  18. GPS determined eastward Sundaland motion with respect to Eurasia confirmed by earthquakes slip vectors at Sunda and Philippine trenches

    NASA Astrophysics Data System (ADS)

    Chamot-Rooke, N.; Le Pichon, X.

    1999-12-01

    GPS measurements acquired over Southeast Asia in 1994 and 1996 in the framework of the GEODYSSEA program revealed that a large piece of continental lithosphere comprising the Indochina Peninsula, Sunda shelf and part of Indonesia behaves as a rigid `Sundaland' platelet. A direct adjustment of velocity vectors obtained in a Eurasian frame of reference shows that Sundaland block is rotating clockwise with respect to Eurasia around a pole of rotation located south of Australia. We present here an additional check of Sundaland motion that uses earthquakes slip vectors at Sunda and Philippine trenches. Seven sites of the GEODYSSEA network are close to the trenches and not separated from them by large active faults (two at Sumatra Trench, three at Java Trench and two at the Philippine Trench). The difference between the vector at the station and the adjacent subducting plate vector defines the relative subduction motion and should thus be aligned with the subduction earthquake slip vectors. We first derive a frame-free solution that minimizes the upper plate (or Sundaland) motion. When corrected for Australia-Eurasia and Philippines-Eurasia NUVEL1-A motion, the misfit between GPS and slip vectors azimuths is significant at 95% confidence, indicating that the upper plate does not belong to Eurasia. We then examine the range of solutions compatible with the slip vectors azimuths and conclude that the minimum velocity of Sundaland is a uniform 7-10 mm/a eastward velocity. However, introducing the additional constraint of the fit of the GEODYSSEA sites with the Australian IGS reference ones, or tie with the NTUS Singapore station, leads to a much narrower range of solutions. We conclude that Sundaland has an eastward velocity of about 10 mm/a on its southern boundary increasing to 16-18 mm/a on its northern boundary.

  19. Shocks, Superbubbles, and Filaments: Investigations into Large Scale Gas Motions in Giant Molecular Clouds

    NASA Astrophysics Data System (ADS)

    Pon, Andrew Richard

    2013-12-01

    Giant molecular clouds (GMCs), out of which stars form, are complex, dynamic systems, which both influence and are shaped by the process of star formation. In this dissertation, I examine three different facets of the dynamical motions within GMCs. Collapse modes in different dimensional objects. Molecular clouds contain lower dimensional substructures, such as filaments and sheets. The collapse properties of finite filaments and sheets differ from those of spherical objects as well as infinite sheets and filaments. I examine the importance of local collapse modes of small central perturbations, relative to global collapse modes, in different dimensional objects to elucidate whether strong perturbations are required for molecular clouds to fragment to form stars. I also calculate the dependence of the global collapse timescale upon the aspect ratio of sheets and filaments. I find that lower dimensional objects are more readily fragmented, and that for a constant density, lower dimensional objects and clouds with larger aspect ratios collapse more slowly. An edge-driven collapse mode also exists in sheets and filaments and is most important in elongated filaments. The failure to consider the geometry of a gas cloud is shown to lead to an overestimation of the star formation rate by up to an order of magnitude. Molecular tracers of turbulent energy dissipation. Molecular clouds contain supersonic turbulence that simulations predict will decay rapidly via shocks. I use shock models to predict which species emit the majority of the turbulent energy dissipated in shocks and find that carbon monoxide, CO, is primarily responsible for radiating away this energy. By combining these shock models with estimates for the turbulent energy dissipation rate of molecular clouds, I predict the expected shock spectra of CO from molecular clouds. I compare the results of these shock models to predictions for the emission from the unshocked gas in GMCs and show that mid

  20. Brownian motion of a matter-wave bright soliton moving through a thermal cloud of distinct atoms

    NASA Astrophysics Data System (ADS)

    McDonald, R. G.; Bradley, A. S.

    2016-06-01

    Taking an open quantum system approach, we derive a collective equation of motion for the dynamics of a matter-wave bright soliton moving through a thermal cloud of a distinct atomic species. The reservoir interaction involves energy transfer without particle transfer between the soliton and thermal cloud, thus damping the soliton motion without altering its stability against collapse. We derive a Langevin equation for the soliton center-of-mass velocity in the form of an Ornstein-Uhlenbeck process with analytical drift and diffusion coefficients. This collective motion is confirmed by simulations of the full stochastic projected Gross-Pitaevskii equation for the matter-wave field. The system offers a pathway for experimentally observing the elusive energy-damping reservoir interaction and a clear realization of collective Brownian motion for a mesoscopic superfluid droplet.

  1. ON THE INTERPRETATION OF RECENT PROPER MOTION DATA FOR THE LARGE MAGELLANIC CLOUD

    SciTech Connect

    Bekki, Kenji

    2011-03-20

    Recent observational studies using the Hubble Space Telescope have derived the center-of-mass proper motion (CMPM) of the Large Magellanic Cloud (LMC). Although these studies carefully treated both rotation and perspective effects in deriving the proper motion (PM) for each of the sampled fields, they did not consider the effects of local random motion in the derivation. This means that the average PM of the fields (i.e., the observed CMPM) could significantly deviate from the true CMPM, because the effect of local random motion cannot be close to zero in making the average PM for the small number of fields ({approx}10). We discuss how significantly the observationally derived CMPM can deviate from the true CMPM by applying the same method as used in the observations for a dynamical model of the LMC with a known true CMPM. We find that the deviation can be as large as {approx}50 km s{sup -1} ({approx}0.21 mas yr{sup -1}), if the LMC has a thick disk and a maximum circular velocity of {approx}120 km s{sup -1}. We also find that the deviation depends both on the total number of sampled fields and on the structure and kinematics of the LMC. We therefore suggest that there is a possibility that the observed CMPM of the LMC deviates from the true one to some extent. We also show that a simple mean of PM for a large number of LMC fields ({approx}1000) can be much closer to the true CMPM.

  2. SU-E-J-115: Correlation of Displacement Vector Fields Calculated by Deformable Image Registration Algorithms with Motion Parameters of CT Images with Well-Defined Targets and Controlled-Motion

    SciTech Connect

    Jaskowiak, J; Ahmad, S; Ali, I; Alsbou, N

    2015-06-15

    Purpose: To investigate correlation of displacement vector fields (DVF) calculated by deformable image registration algorithms with motion parameters in helical axial and cone-beam CT images with motion artifacts. Methods: A mobile thorax phantom with well-known targets with different sizes that were made from water-equivalent material and inserted in foam to simulate lung lesions. The thorax phantom was imaged with helical, axial and cone-beam CT. The phantom was moved with a cyclic motion with different motion amplitudes and frequencies along the superior-inferior direction. Different deformable image registration algorithms including demons, fast demons, Horn-Shunck and iterative-optical-flow from the DIRART software were used to deform CT images for the phantom with different motion patterns. The CT images of the mobile phantom were deformed to CT images of the stationary phantom. Results: The values of displacement vectors calculated by deformable image registration algorithm correlated strongly with motion amplitude where large displacement vectors were calculated for CT images with large motion amplitudes. For example, the maximal displacement vectors were nearly equal to the motion amplitudes (5mm, 10mm or 20mm) at interfaces between the mobile targets lung tissue, while the minimal displacement vectors were nearly equal to negative the motion amplitudes. The maximal and minimal displacement vectors matched with edges of the blurred targets along the Z-axis (motion-direction), while DVF’s were small in the other directions. This indicates that the blurred edges by phantom motion were shifted largely to match with the actual target edge. These shifts were nearly equal to the motion amplitude. Conclusions: The DVF from deformable-image registration algorithms correlated well with motion amplitude of well-defined mobile targets. This can be used to extract motion parameters such as amplitude. However, as motion amplitudes increased, image artifacts increased

  3. Laser filamentation induced air-flow motion in a diffusion cloud chamber.

    PubMed

    Sun, Haiyi; Liu, Jiansheng; Wang, Cheng; Ju, Jingjing; Wang, Zhanxin; Wang, Wentao; Ge, Xiaochun; Li, Chuang; Chin, See Leang; Li, Ruxin; Xu, Zhizhan

    2013-04-22

    We numerically simulated the air-flow motion in a diffusion cloud chamber induced by femtosecond laser filaments for different chopping rates. A two dimensional model was employed, where the laser filaments were treated as a heat flux source. The simulated patterns of flow fields and maximum velocity of updraft compare well with the experimental results for the chopping rates of 1, 5, 15 and 150 Hz. A quantitative inconsistency appears between simulated and experimental maximum velocity of updraft for 1 kHz repetition rate although a similar pattern of flow field is obtained, and the possible reasons were analyzed. Based on the present simulated results, the experimental observation of more water condensation/snow at higher chopping rate can be explained. These results indicate that the specific way of laser filament heating plays a significant role in the laser-induced motion of air flow, and at the same time, our previous conclusion of air flow having an important effect on water condensation/snow is confirmed. PMID:23609636

  4. Parallel algorithm for determining motion vectors in ice floe images by matching edge features

    NASA Technical Reports Server (NTRS)

    Manohar, M.; Ramapriyan, H. K.; Strong, J. P.

    1988-01-01

    A parallel algorithm is described to determine motion vectors of ice floes using time sequences of images of the Arctic ocean obtained from the Synthetic Aperture Radar (SAR) instrument flown on-board the SEASAT spacecraft. Researchers describe a parallel algorithm which is implemented on the MPP for locating corresponding objects based on their translationally and rotationally invariant features. The algorithm first approximates the edges in the images by polygons or sets of connected straight-line segments. Each such edge structure is then reduced to a seed point. Associated with each seed point are the descriptions (lengths, orientations and sequence numbers) of the lines constituting the corresponding edge structure. A parallel matching algorithm is used to match packed arrays of such descriptions to identify corresponding seed points in the two images. The matching algorithm is designed such that fragmentation and merging of ice floes are taken into account by accepting partial matches. The technique has been demonstrated to work on synthetic test patterns and real image pairs from SEASAT in times ranging from .5 to 0.7 seconds for 128 x 128 images.

  5. The Impact of Satellite Atmospheric Motion Vectors in the GMAO GEOS-5 Global Data Assimilation System

    NASA Technical Reports Server (NTRS)

    Gelaro, R. D.; Merkova, D.; Tai, King-Sheng; McCarty, W.

    2012-01-01

    The impact of satellite-derived atmospheric motion vectors (AMVs) on numerical weather forecasts is examined using the GEOS-5 global atmospheric data assimilation system. Cycling data assimilation experiments, including twice-daily 5-day forecasts, are conducted for two 6-week periods during the 2010 Atlantic hurricane season and 2010-2011Northern Hemisphere winter season. Results from a control experiment that includes all AMVs and other data types assimilated operationally in GEOS-5 are compared with those from an experiment in which the GEOS-5 AMVs (only) are replaced by ones produced by the U. S. Navy?s NAVDAS-AR atmospheric data assimilation system. The Navy AMVs are assimilated in their entirety as well as in various subset combinations. The primary objective of these experiments is to determine whether aspects of the NAVDAS-AR data selection and quality control procedure, especially the use of carefully averaged ("super-ob?) wind vectors and large volume of AMVs, explain the typically larger beneficial impact of these data in the Navy system as compared with most other forecast systems. Adjoint-based observation impact calculations are assessed and compared with traditional metrics such as forecast geopotential height anomaly correlations and observation-minus-forecast departures. Results so far indicate that that the greater number of NRL AMVs is primarily responsible for their larger impact, although superobing also appears to be beneficial. Map views show that the impact obtained from assimilation of the NRL AMVs is more uniformly beneficial, perhaps due to the averaging of individual observations in creating the super-obs. While the NRL AMVs have a much larger impact in GEOS-5 than do the control AMVs, their impact is still smaller than in the Navy forecast system, suggesting that the mix of observations may play an important role in modulating the impact of any one data type. At the same time, reducing the number of satellite radiances assimilated in

  6. A new classification algorithm based on multi-kernel Support Vector Machine on infrared cloud background image

    NASA Astrophysics Data System (ADS)

    Wang, Tiebing; Zhou, Yiyu; Xu, Shenda; Cheng, Chuxiong

    2015-11-01

    A new classification algorithm based on multi-kernel support vector machine (SVM) was proposed for classification problems on infrared cloud background image. The experimental results show that the method integrates the advantages of polynomial kernel functions, Gaussian radial kernel functions and multilayer perception kernel functions. Compared with the traditional single-kernel SVM classification method, the proposed method has better performance both in local interpolation and global extrapolation, and is more suitable for SVM classification problems when the training sample size is small. Experimental results show the superiority of the proposed algorithm..

  7. Cloud shadow Speed Sensor (CSS)

    NASA Astrophysics Data System (ADS)

    Fung, Victor

    Changing cloud cover is a major source of solar radiation variability and poses challenges for the integration of solar energy. A compact and economical system that measures cloud shadow motion vectors to estimate power plant ramp rates and provide short-term forecasting is presented. The Cloud shadow Speed Sensor (CSS) is constructed using an array of luminance sensors and a high-speed data acquisition system to resolve the progression of cloud passages across the sensor footprint. An embedded microcontroller acquires the sensor data and uses a cross-correlation algorithm to determine cloud shadow motion vectors. The CSS was validated against an artificial shading test apparatus, an alternative method of cloud motion detection from ground-measured irradiance (linear cloud edge, LCE), and a UC San Diego sky imager (USI). The CSS detected artificial shadow directions and speeds to within 15° and 6 % accuracy, respectively. The CSS detected (real) cloud shadow directions and speeds with average weighted root-mean-square difference of 22° and 1.9 m s-1 when compared to USI and 33° and 1.5 m s -1 when compared to LCE results.

  8. Hurricane Debby - An illustration of the complementary nature of VAS soundings and cloud and water vapor motion winds. [Visible Infrared Spin Scan Radiometer Atmospheric Sounder

    NASA Technical Reports Server (NTRS)

    Le Marshall, J. F.; Smith, W. L.; Callan, G. M.

    1985-01-01

    The utility of VISSR Atmospheric Sounder (VAS) temperature and moisture soundings and cloud and water vapor motion winds in defining a storm and its surroundings at subsynoptic scales has been examined using a numerical analysis and prognosis system. It is shown that the VAS temperature and moisture data, which specify temperature and moisture well in cloud-free areas, are complemented by cloud and water vapor motion data generated in the cloudy areas. The cloud and water vapor 'winds' provide thermal gradient information for interpolating the soundings across cloudy regions. The loss of analysis integrity due to the reduction of VAS sounding density in the cloudy regions associated with synoptic activity is ameliorated by using cloud and water vapor motion winds. The improvement in numerical forecasts resulting from the addition of these data to the numerical analysis is recorded.

  9. Roll tracking effects of G-vector tilt and various types of motion washout

    NASA Technical Reports Server (NTRS)

    Jex, H. R.; Magdaleno, R. E.; Junker, A. M.

    1978-01-01

    In a dogfight scenario, the task was to follow the target's roll angle while suppressing gust disturbances. All subjects adopted the same behavioral strategies in following the target while suppressing the gusts, and the MFP-fitted math model response was generally within one data symbol width. The results include the following: (1) comparisons of full roll motion (both with and without the spurious gravity tilt cue) with the static case. These motion cues help suppress disturbances with little net effect on the visual performance. Tilt cues were clearly used by the pilots but gave only small improvement in tracking errors. (2) The optimum washout (in terms of performance close to real world, similar behavioral parameters, significant motion attenuation (60 percent), and acceptable motion fidelity) was the combined attenuation and first-order washout. (3) Various trends in parameters across the motion conditions were apparent, and are discussed with respect to a comprehensive model for predicting adaptation to various roll motion cues.

  10. The kinematical analysis of proper motions and radial velocities of stars by means of the vector spherical harmonics

    NASA Astrophysics Data System (ADS)

    Tsvetkov, A.; Vityazev, . V.; , Kumkova I. I.

    2009-09-01

    The paper describes the application of the 3-D vector spherical harmonics (henceforth VSH) to the investigation of stellar kinematics. The VSH technique is suitable for present and future catalogues which contain all three components of velocity vector: proper motions and radial velocities. In general, the VSH allows to detect all the systematic components in the stellar velocity field and does not depend on any model. If some physical model is used, the VSH not only determines the parameters of the model, but detects the systematic components which are beyond the model. The application of the VSH to the Hipparcos data complimented with radial velocities discovers the systematic components which are beyond the linear Ogorodnikov-milne model.

  11. Primer vector theory applied to the linear relative-motion equations. [for N-impulse space trajectory optimization

    NASA Technical Reports Server (NTRS)

    Jezewski, D.

    1980-01-01

    Prime vector theory is used in analyzing a set of linear relative-motion equations - the Clohessy-Wiltshire (C/W) equations - to determine the criteria and necessary conditions for an optimal N-impulse trajectory. The analysis develops the analytical criteria for improving a solution by: (1) moving any dependent or independent variable in the initial and/or final orbit, and (2) adding intermediate impulses. If these criteria are violated, the theory establishes a sufficient number of analytical equations. The subsequent satisfaction of these equations will result in the optimal position vectors and times of an N-impulse trajectory. The solution is examined for the specific boundary conditions of: (1) fixed-end conditions, two impulse, and time-open transfer; (2) an orbit-to-orbit transfer; and (3) a generalized renezvous problem.

  12. Thin cloud removal from remote sensing images using multidirectional dual tree complex wavelet transform and transfer least square support vector regression

    NASA Astrophysics Data System (ADS)

    Hu, Gensheng; Li, Xiaoyi; Liang, Dong

    2015-01-01

    The existence of clouds affects the interpretation and utilization of remote sensing images. A thin cloud removal algorithm for cloud-contaminated remote sensing images is proposed by combining a multidirectional dual tree complex wavelet transform (M-DTCWT) with domain adaptation transfer least square support vector regression (T-LSSVR). First, M-DTCWT is constructed by using the hourglass filter bank in combination with DTCWT, which is used to decompose remote sensing images into multiscale and multidirectional subbands. Then the low-frequency subband coefficients of the cloud-free regions on target images and source domain images are used as samples for a T-LSSVR model, which can be used to predict those of the cloud regions on cloud-contaminated images. Finally, by enhancing the high-frequency coefficients and replacing the low-frequency coefficients, the thin clouds on cloud-contaminated images are removed. Experimental results show that M-DTCWT contributes to keeping the details of the ground objects of cloud-contaminated images, and the T-LSSVR model can effectively learn the contour information from multisource and multitemporal images, therefore, the proposed method achieves a good effect of thin cloud removal.

  13. Global rotational motion and displacement estimation of digital image stabilization based on the oblique vectors matching algorithm

    NASA Astrophysics Data System (ADS)

    Yu, Fei; Hui, Mei; Zhao, Yue-jin

    2009-08-01

    The image block matching algorithm based on motion vectors of correlative pixels in oblique direction is presented for digital image stabilization. The digital image stabilization is a new generation of image stabilization technique which can obtains the information of relative motion among frames of dynamic image sequences by the method of digital image processing. In this method the matching parameters are calculated from the vectors projected in the oblique direction. The matching parameters based on the vectors contain the information of vectors in transverse and vertical direction in the image blocks at the same time. So the better matching information can be obtained after making correlative operation in the oblique direction. And an iterative weighted least square method is used to eliminate the error of block matching. The weights are related with the pixels' rotational angle. The center of rotation and the global emotion estimation of the shaking image can be obtained by the weighted least square from the estimation of each block chosen evenly from the image. Then, the shaking image can be stabilized with the center of rotation and the global emotion estimation. Also, the algorithm can run at real time by the method of simulated annealing in searching method of block matching. An image processing system based on DSP was used to exam this algorithm. The core processor in the DSP system is TMS320C6416 of TI, and the CCD camera with definition of 720×576 pixels was chosen as the input video signal. Experimental results show that the algorithm can be performed at the real time processing system and have an accurate matching precision.

  14. The relationship between large-scale vertical motion, highly reflective cloud, and sea surface temperature in the tropical Pacific region

    NASA Technical Reports Server (NTRS)

    Zimmermann, Peter H.; Newell, Reginald E.; Selkirk, Henry B.

    1988-01-01

    Vertical motion fields at 850 mbar over the tropical Pacific region are calculated from the 1963-1973 mean wind fields for 4 months of the year and for October 1972, the peak month in the 1972-1973 El Nino event. These vertical motion fields are derived using the projective separation technique, which has the unique property of separating vertical motion into components due to meridional wind convergence and zonal wind convergence. This separation permits investigation of the response of the Hadley and Walker circulations to annual and interannual variation of the sea surface temperature in the tropical Pacific. The large-scale features of the computed vertical motion fields are in agreement with those of highly reflective clouds, which indicate the locations of deep convection. Examination of the annual cycle of the vertical motion and its components shows no strong variation of the Walker circulation with the east-west gradient of sea surface temperature. On the other hand, a strong correlation is found between meridional overturning in the eastern Pacific and the local equatorial sea surface temperature: during El Nino events, the eastern and central Pacific contribution to the Hadley circulation tends to increase.

  15. Influence of the cosmic repulsion on the MOND model of the Magellanic Cloud motion in the field of Milky Way

    SciTech Connect

    Schee, J.; Stuchlík, Z.; Petrásek, M. E-mail: zdenek.stuchlik@fpf.slu.cz

    2013-12-01

    It has been recently shown that the cosmic repulsion can have a highly significant influence on the motion of Magellanic Clouds (MC) in the gravitational field of Milky Way, treated in the framework of the Cold Dark Matter (CDM) halo model. However, there is an alternative to the CDM halo explanation of the rotation curves in the periphery of spiral galaxies, based on MOdified Newtonian Dynamics (MOND). Therefore, we study the role of the cosmic repulsion in the framework of the MOND theory applied to determine the MC motion. Our results demonstrate that in the MOND framework the influence of the cosmic repulsion on the motion of both Small and Large MC is also highly significant, but it is of a different character than in the framework of the CDM halo model. Moreover, we demonstrate that the MC motion in the framework of the CDM halo and MOND models is subtantially different and can serve as a test of these fundamentally different approaches to the explanation of the phenomena related to galaxies and the motion of satellite galaxies.

  16. THIRD-EPOCH MAGELLANIC CLOUD PROPER MOTIONS. I. HUBBLE SPACE TELESCOPE/WFC3 DATA AND ORBIT IMPLICATIONS

    SciTech Connect

    Kallivayalil, Nitya; Van der Marel, Roeland P.; Anderson, Jay; Besla, Gurtina; Alcock, Charles

    2013-02-20

    We present proper motions for the Large and Small Magellanic Clouds (LMC and SMC) based on three epochs of Hubble Space Telescope data, spanning a {approx}7 yr baseline, and centered on fields with background QSOs. The first two epochs, the subject of past analyses, were obtained with ACS/HRC, and have been reanalyzed here. The new third epoch with WFC3/UVIS increases the time baseline and provides better control of systematics. The three-epoch data yield proper-motion random errors of only 1%-2% per field. For the LMC this is sufficient to constrain the internal proper-motion dynamics, as will be discussed in a separate paper. Here we focus on the implied center-of-mass proper motions: {mu} {sub W,LMC} = -1.910 {+-} 0.020 mas yr{sup -1}, {mu} {sub N,LMC} = 0.229 {+-} 0.047 mas yr{sup -1}, and {mu} {sub W,SMC} = -0.772 {+-} 0.063 mas yr{sup -1}, {mu} {sub N,SMC} = -1.117 {+-} 0.061 mas yr{sup -1}. We combine the results with a revised understanding of the solar motion in the Milky Way to derive Galactocentric velocities: v {sub tot,LMC} = 321 {+-} 24 km s{sup -1} and v {sub tot,SMC} = 217 {+-} 26 km s{sup -1}. Our proper-motion uncertainties are now dominated by limitations in our understanding of the internal kinematics and geometry of the Clouds, and our velocity uncertainties are dominated by distance errors. Orbit calculations for the Clouds around the Milky Way allow a range of orbital periods, depending on the uncertain masses of the Milky Way and LMC. Periods {approx}< 4 Gyr are ruled out, which poses a challenge for traditional Magellanic Stream models. First-infall orbits are preferred (as supported by other arguments as well) if one imposes the requirement that the LMC and SMC must have been a bound pair for at least several Gyr.

  17. System identification modeling of ship manoeuvring motion in 4 degrees of freedom based on support vector machines

    NASA Astrophysics Data System (ADS)

    Wang, Xue-gang; Zou, Zao-jian; Yu, Long; Cai, Wei

    2015-06-01

    Based on support vector machines, three modeling methods, i.e., white-box modeling, grey-box modeling and black-box modeling of ship manoeuvring motion in 4 degrees of freedom are investigated. With the whole-ship mathematical model for ship manoeuvring motion, in which the hydrodynamic coefficients are obtained from roll planar motion mechanism test, some zigzag tests and turning circle manoeuvres are simulated. In the white-box modeling and grey-box modeling, the training data taken every 5 s from the simulated 20°/20° zigzag test are used, while in the black-box modeling, the training data taken every 5 s from the simulated 15°/15°, 20°/20° zigzag tests and 15°, 25° turning manoeuvres are used; and the trained support vector machines are used to predict the whole 20°/20° zigzag test. Comparisons between the simulated and predicted 20?/20° zigzag tests show good predictive ability of the proposed methods. Besides, all mathematical models obtained by the proposed modeling methods are used to predict the 10°/10° zigzag test and 35° turning circle manoeuvre, and the predicted results are compared with those of simulation tests to demonstrate the good generalization performance of the mathematical models. Finally, the proposed modeling methods are analyzed and compared with each other in aspects of application conditions, prediction accuracy and computation speed. The appropriate modeling method can be chosen according to the intended use of the mathematical models and the available data needed for system identification.

  18. VizieR Online Data Catalog: OGLE-III. Magellanic Clouds stellar proper motions (Poleski+, 2012)

    NASA Astrophysics Data System (ADS)

    Poleski, R.; Soszynski, I.; Udalski, A.; Szymanski, M. K.; Kubiak, M.; Pietrzynski, G.; Wyrzykowski, L.; Ulaczyk, K.

    2015-07-01

    The OGLE-III project observed the Large Magellanic Cloud, the Small Magellanic Cloud, and the globular cluster 47 Tuc between 2001 and 2009 with the 1.3-m Warsaw telescope, which is situated at the Las Campanas Observatory, Chile. The telescope was equipped with an eight-chip mosaic CCD camera. The field of view was 36'x36' and the pixel scale was 0.26"/pix. I-band filter was used. (5 data files).

  19. Large-scale Environmental Variables and Transition to Deep Convection in Cloud Resolving Model Simulations: A Vector Representation

    SciTech Connect

    Hagos, Samson M.; Leung, Lai-Yung R.

    2012-11-01

    Cloud resolving model simulations and vector analysis are used to develop a quantitative method of assessing regional variations in the relationships between various large-scale environmental variables and the transition to deep convection. Results of the CRM simulations from three tropical regions are used to cluster environmental conditions under which transition to deep convection does and does not take place. Projections of the large-scale environmental variables on the difference between these two clusters are used to quantify the roles of these variables in the transition to deep convection. While the transition to deep convection is most sensitive to moisture and vertical velocity perturbations, the details of the profiles of the anomalies vary from region to region. In comparison, the transition to deep convection is found to be much less sensitive to temperature anomalies over all three regions. The vector formulation presented in this study represents a simple general framework for quantifying various aspects of how the transition to deep convection is sensitive to environmental conditions.

  20. Flare activity, sunspot motions, and the evolution of vector magnetic fields in Hale region 17244

    NASA Technical Reports Server (NTRS)

    Neidig, Donald F.; Hagyard, Mona J.; Machado, Marcos E.; Smith, Jesse B., Jr.

    1986-01-01

    The magnetic and dynamical circumstances leading to the 1B/M4 flare of November 5, 1980 are studied, and a strong association is found between the buildup of magnetic shear and the onset of flare activity within the active region. The development of shear, as observed directly in vector magnetograms, is consistent in detail with the dynamical history of the active region and identifies the precise location of the optical and hard-X-ray kernels of the flare emission.

  1. Vertical air motions over the Tropical Western Pacific for validating cloud resolving and regional models

    SciTech Connect

    Williams, Christopher R.

    2015-03-16

    The objective of this project was to estimate the vertical air motion using Doppler velocity spectra from two side-by-side vertically pointing radars. The retrieval technique was applied to two different sets of radars. This first set was 50- and 920-MHz vertically pointing radars near Darwin, Australia. The second set was 449-MHz and 2.8-GHz vertically pointing radars deployed at SGP for MC3E. The retrieval technique uses the longer wavelength radar (50 or 449 MHz) to observe both the vertical air motion and precipitation motion while the shorter wavelength radar (920 MHz or 2.8 GHz) observes just the precipitation motion. By analyzing their Doppler velocity spectra, the precipitation signal in the 920 MHz or 2.8 GHz radar is used to mask-out the precipitation signal in the 50 or 449 MHz radar spectra, leaving just the vertical air motion signal.

  2. On the orbital motion of cold clouds in broad-line regions

    NASA Astrophysics Data System (ADS)

    Shadmehri, Mohsen

    2015-08-01

    We study the orbit of a pressure-confined cloud in the broad-line region (BLR) of active galactic nuclei when the combined effects of the central gravity and anisotropic radiation pressure and the drag force are considered. The physical properties of the intercloud gas, such as its pressure and dynamic viscosity, are defined as power-law functions of the radial distance. For a drag force proportional to the relative velocity of a cloud and the background gas, a detailed analysis of the orbits is performed for different values of the input parameters. We also present analytical solutions for when the intercloud pressure is uniform and the viscosity is proportional to the inverse square of the radial distance. Our analytical and numerical solutions demonstrate decay of the orbits due to the drag force, so that a cloud will eventually fall on to the central region after the so-called time-of-flight. We found that the time-of-flight of a BLR cloud is proportional to the inverse of the dimensionless drag coefficient. If the time-of-flight becomes shorter than the lifetime of the whole system, then mechanisms for continually forming BLR clouds are needed.

  3. The VMC survey. XVII. Proper motions of the Small Magellanic Cloud and the Milky Way globular cluster 47 Tucanae

    NASA Astrophysics Data System (ADS)

    Cioni, Maria-Rosa L.; Bekki, Kenji; Girardi, Léo; de Grijs, Richard; Irwin, Mike J.; Ivanov, Valentin D.; Marconi, Marcella; Oliveira, Joana M.; Piatti, Andrés E.; Ripepi, Vincenzo; van Loon, Jacco Th.

    2016-02-01

    Aims: In this study we use multi-epoch near-infrared observations from the VISTA survey of the Magellanic Cloud system (VMC) to measure the proper motions of different stellar populations in a tile of 1.5 deg2 in size in the direction of the Galactic globular cluster 47 Tuc. We obtain the proper motion of the cluster itself, of the Small Magellanic Cloud (SMC), and of the field Milky Way stars. Methods: Stars of the three main stellar components are selected according to their spatial distributions and their distributions in colour-magnitude diagrams. Their average coordinate displacement is computed from the difference between multiple Ks-band observations for stars as faint as Ks = 19 mag. Proper motions are derived from the slope of the best-fitting line among ten VMC epochs over a time baseline of ~1 yr. Background galaxies are used to calibrate the absolute astrometric reference frame. Results: The resulting absolute proper motion of 47 Tuc is (μαcos(δ), μδ) = (+7.26 ± 0.03, -1.25 ± 0.03) mas yr-1. This measurement refers to about 35 000 sources distributed between 10' and 60' from the cluster centre. For the SMC we obtain (μαcos(δ), μδ) = (+1.16 ± 0.07, -0.81 ± 0.07) mas yr-1 from about 5250 red clump and red giant branch stars. The absolute proper motion of the Milky Way population in the line of sight (l = 305.9, b = -44.9) of this VISTA tile is (μαcos(δ), μδ) = (+10.22 ± 0.14, -1.27 ± 0.12) mas yr-1 and has been calculated from about 4000 sources. Systematic uncertainties associated with the astrometric reference system are 0.18 mas yr-1. Thanks to the proper motion we detect 47 Tuc stars beyond its tidal radius. Based on observations made with VISTA at the Paranal Observatory under program ID 179.B-2003.

  4. Analytic evaluation of the nonadiabatic coupling vector between excited states using equation-of-motion coupled-cluster theory

    NASA Astrophysics Data System (ADS)

    Tajti, Attila; Szalay, Péter G.

    2009-09-01

    Theory and implementation for evaluation of the nonadiabatic coupling vector between excited electronic states described by equation-of-motion excitation energy coupled-cluster singles and doubles (EOMEE-CCSD) method is presented. Problems arising from the non-Hermitian nature of the theory are discussed in detail. The performance of the new approach is demonstrated by the nice agreement of the nonadiabatic coupling curves for LiH obtained at the EOMEE-CCSD and MR-CISD levels. Using the tools developed we also present a computational procedure to evaluate the interstate coupling constants used in vibronic coupling theories. As an application of this part of the implementation we present simulation of the electronic absorption spectrum of the pyrazine molecule within the linear vibronic coupling model.

  5. Vector constraints on western U.S. deformation from space geodesy, neotectonics, and plate motions

    NASA Technical Reports Server (NTRS)

    Minster, J. Bernard; Jordan, Thomas H.

    1987-01-01

    The rate-of-slip vector on the San Andreas fault in central California estimated from geodetic and Holocene geological data is inconsistent with the prediction of rigid plate models such as RM2. This well-known 'San Andreas discrepancy' is diagnostic of plate deformation distributed both east of the fault in the Basin and Range and west of the fault along the California continental margin. Constraints on the integrated deformation rates across these two regions consistent with: (1) the kinematical boundary conditions imposed by the rigid plate model; (2) neotectonic and paleoseismic estimates of deformation rates; (3) ground-based geodetic measurements; and (4) rates of change observed by very long baseline interferometry along seven baselines to western U.S. sites are constructed. The space-geodetic data on Basin and Range extension taken over a 4-year interval are compatible with geological observations averaged over the Holocene; the best estimate of its integrated deformation rate, provided by the joint inversion of both data types, is 9.7 + or - 2.1 mm/yr, N 56 deg W + or - 10 deg, too small and in the wrong direction to account entirely for the San Andreas discrepancy. The integral of this deformation, estimated by subtracting the Basin and Range contribution from the discrepancy vector, requires significant right-lateral shear parallel to the San Andreas (13 + or - 5 mm/yr) and some compression perpendicular to it (9 + or - 3 mm/yr).

  6. Third-epoch Magellanic Cloud proper motions. II. The large Magellanic Cloud rotation field in three dimensions

    SciTech Connect

    Van der Marel, Roeland P.; Kallivayalil, Nitya

    2014-02-01

    We present the first detailed assessment of the large-scale rotation of any galaxy based on full three-dimensional velocity measurements. We do this for the LMC by combining our Hubble Space Telescope average proper motion (PM) measurements for stars in 22 fields, with existing line-of-sight (LOS) velocity measurements for 6790 individual stars. We interpret these data with a model of circular rotation in a flat disk. The PM and LOS data paint a consistent picture of the LMC rotation, and their combination yields several new insights. The PM data imply a stellar dynamical center that coincides with the H I dynamical center, and a rotation curve amplitude consistent with that inferred from LOS velocity studies. The implied disk viewing angles agree with the range of values found in the literature, but continue to indicate variations with stellar population and/or radius. Young (red supergiant) stars rotate faster than old (red and asymptotic giant branch) stars due to asymmetric drift. Outside the central region, the circular velocity is approximately flat at V {sub circ} = 91.7 ± 18.8 km s{sup –1}. This is consistent with the baryonic Tully-Fisher relation and implies an enclosed mass M(8.7 kpc) = (1.7 ± 0.7) × 10{sup 10} M {sub ☉}. The virial mass is larger, depending on the full extent of the LMC's dark halo. The tidal radius is 22.3 ± 5.2 kpc (24.°0 ± 5.°6). Combination of the PM and LOS data yields kinematic distance estimates for the LMC, but these are not yet competitive with other methods.

  7. THE M31 VELOCITY VECTOR. I. HUBBLE SPACE TELESCOPE PROPER-MOTION MEASUREMENTS

    SciTech Connect

    Sohn, Sangmo Tony; Anderson, Jay; Van der Marel, Roeland P.

    2012-07-01

    We present the first proper-motion (PM) measurements for the galaxy M31. We obtained new V-band imaging data with the Hubble Space Telescope ACS/WFC and the WFC3/UVIS instruments of three fields: a spheroid field near the minor axis, an outer disk field along the major axis, and a field on the Giant Southern Stream. The data provide five to seven year time baselines with respect to pre-existing deep first-epoch observations of the same fields. We measure the positions of thousands of M31 stars and hundreds of compact background galaxies in each field. High accuracy and robustness is achieved by building and fitting a unique template for each individual object. The average PM for each field is obtained from the average motion of the M31 stars between the epochs with respect to the background galaxies. For the three fields, the observed PMs ({mu}{sub W}, {mu}{sub N}) are, in units of mas yr{sup -1}, (- 0.0458, -0.0376) {+-} (0.0165, 0.0154), (- 0.0533, -0.0104) {+-} (0.0246, 0.0244), and (- 0.0179, -0.0357) {+-} (0.0278, 0.0272), respectively. The ability to average over large numbers of objects and over the three fields yields a final displacement accuracy of a few thousandths of a pixel, corresponding to only 12 {mu}as yr{sup -1}. This is comparable to what has been achieved for other Local Group galaxies using Very Long Baseline Array observations of water masers. Potential systematic errors are controlled by an analysis strategy that corrects for detector charge transfer inefficiency, spatially and time-dependent geometric distortion, and point-spread function variations. The robustness of the PM measurements and uncertainties are supported by the fact that data from different instruments, taken at different times and with different telescope orientations, as well as measurements of different fields, all yield statistically consistent results. Papers II and III of this series explore the implications of the new measurements for our understanding of the history

  8. Apsidal motions of 90 eccentric binary systems in the Small Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Hong, Kyeongsoo; Lee, Jae Woo; Kim, Seung-Lee; Koo, Jae-Rim; Lee, Chung-UK

    2016-04-01

    We examined light curves of 1138 stars brighter than 18.0 mag in the I band and less than a mean magnitude error of 0.1 mag in the V band from the OGLE-III eclipsing binary catalogue, and found 90 new binary systems exhibiting apsidal motion. In this study, the samples of apsidal motion stars in the SMC were increased by a factor of about 3.0 than previously known. In order to determine the period of the apsidal motion for the binaries, we analysed in detail both the light curves and eclipse timings using the MACHO and OGLE photometric database. For the eclipse timing diagrams of the systems, new times of minimum light were derived from the full light curve combined at intervals of one year from the survey data. The new 90 binaries have apsidal motion periods in the range of 12-897 years. An additional short-term oscillation was detected in four systems (OGLE-SMC-ECL-1634, 1947, 3035, and 4946), which most likely arises from the existence of a third body orbiting each eclipsing binary. Since the systems presented here are based on homogeneous data and have been analysed in the same way, they are suitable for further statistical analysis.

  9. Motion.

    ERIC Educational Resources Information Center

    Gerhart, James B.; Nussbaum, Rudi H.

    This monograph was written for the Conference on the New Instructional Materials in Physics held at the University of Washington in summer, 1965. It is intended for use in an introductory course in college physics. It consists of an extensive qualitative discussion of motion followed by a detailed development of the quantitative methods needed to…

  10. Motion.

    ERIC Educational Resources Information Center

    Brand, Judith, Ed.

    2002-01-01

    This issue of Exploratorium Magazine focuses on the topic of motion. Contents include: (1) "First Word" (Zach Tobias); (2) "Cosmic Collisions" (Robert Irion); (3) "The Mobile Cell" (Karen E. Kalumuck); (4) "The Paths of Paths" (Steven Vogel); (5) "Fragments" (Pearl Tesler); (6) "Moving Pictures" (Amy Snyder); (7) "Plants on the Go" (Katharine…

  11. ULTRAVIOLET INDUCED MOTION OF A FLUORESCENT DUST CLOUD IN AN ARGON DIRECT CURRENT GLOW DISCHARGE PLASMA

    SciTech Connect

    Hvasta, M.G.; and Zwicker, A.

    2008-01-01

    Dusty plasmas consist of electrons, ions, neutrals and nm-μm sized particles commonly referred to as dust. In man-made plasmas this dust may represent impurities in a tokamak or plasma etching processing. In astrophysical plasmas this dust forms structures such as planetary rings and comet tails. To study dusty plasma dynamics an experiment was designed in which a 3:1 silica (<5 μm diameter) and fl uorescent dust mixture was added to an argon DC glow discharge plasma and exposed to UV radiation. This fl uorescent lighting technique offers an advantage over laser scattering (which only allows two-dimensional slices of the cloud to be observed) and is simpler than scanning mirror techniques or particle image velocimetry. Under typical parameters (P=150 mTorr, V anode= 100 V, Vcathode= -400 V, Itotal < 2mA) when the cloud is exposed to the UV light (100W, λ = 365 nm) the mixture fl uoresces, moves ~2mm towards the light source and begins rotating in a clockwise manner (as seen from the cathode). By calibrating a UV lamp and adjusting the relative intensity of the UV with a variable transformer it was found that both translational and rotational velocities are a function of UV intensity. Additionally, it was determined that bulk cloud rotation is not seen when the dust tray is not grounded while bulk translation is. This ongoing experiment represents a novel way to control contamination in man-made plasmas and a path to a better understanding of UV-bathed plasma systems in space..

  12. Investigation of cloud/water vapor motion winds from geostationary satellite

    NASA Technical Reports Server (NTRS)

    Nieman, Steve; Velden, Chris; Hayden, Kit; Menzel, Paul

    1993-01-01

    Work has been primarily focussed on three tasks: (1) comparison of wind fields produced at MSFC with the CO2 autowind/autoeditor system newly installed in NESDIS operations; (2) evaluation of techniques for improved tracer selection through use of cloud classification predictors; and (3) development of height assignment algorithm with water vapor channel radiances. The contract goal is to improve the CIMSS wind system by developing new techniques and assimilating better existing techniques. The work reported here was done in collaboration with the NESDIS scientists working on the operational winds software, so that NASA funded research can benefit NESDIS operational algorithms.

  13. 34/45-Mbps 3D HDTV digital coding scheme using modified motion compensation with disparity vectors

    NASA Astrophysics Data System (ADS)

    Naito, Sei; Matsumoto, Shuichi

    1998-12-01

    This paper describes a digital compression coding scheme for transmitting three dimensional stereo HDTV signals with full resolution at bit-rates around 30 to 40 Mbps to be adapted for PDH networks of the CCITT 3rd digital hierarchy, 34 Mbps and 45 Mbps, SDH networks of 52 Mbps and ATM networks. In order to achieve a satisfactory quality for stereo HDTV pictures, three advanced key technologies are introduced into the MPEG-2 Multi-View Profile, i.e., a modified motion compensation using disparity vectors estimated between the left and right pictures, an adaptive rate control using a common buffer memory for left and right pictures encoding, and a discriminatory bit allocation which results in the improvement of left pictures quality without any degradation of right pictures. From the results of coding experiment conducted to evaluate the coding picture achieved by this coding scheme, it is confirmed that our coding scheme gives satisfactory picture quality even at 34 Mbps including audio and FEC data.

  14. Belt-Zone Contrasts in Vertical Motion and Cloud Structure in Jupiter's Troposphere

    NASA Astrophysics Data System (ADS)

    Liu, J.; Schneider, T.

    2015-12-01

    It is known that the eddy fluxes of angular momentum in Jupiter's upper troposphere converge in prograde jets and diverge in retrograde jets. Away from the equator, this implies convergence of the Eulerian mean meridional flow in zones (anticyclonic shear) and divergence in belts (cyclonic shear). It suggests lower-tropospheric downwelling in zones and upwelling in belts because the mean meridional circulation almost certainly closes at depth. Yet the banded structure of Jupiter's clouds and hazes suggests that there is upwelling in the brighter zones and downwelling in the darker belts. Here we show that this apparent contradiction can be resolved by considering not the Eulerian but the transformed Eulerian mean circulation, which includes a Stokes drift owing to eddies and is a better approximation of the Lagrangian mean transport of tracers such as ammonia. The structure of the potential vorticity inferred from observations paired with mixing length arguments suggests that there is transformed Eulerian mean upwelling in zones and downwelling in belts, and that this transformed Eulerian mean flow is about an order of magnitude stronger than the Eulerian mean flow. Simulations with a general circulation model of Jupiter's upper atmosphere demonstrate the plausibility of these inferences.

  15. A Benchmark for Cloud Tracking Wind Measurements

    NASA Astrophysics Data System (ADS)

    Sayanagi, K. M.; Mitchell, J.; Ingersoll, A. P.; Ewald, S. P.; Marcus, P. S.; de Pater, I.; Wong, M. H.; Choi, D. S.; Sussman, M.; Ogohara, K.; Imamura, T.; Kouyama, T.; Takagi, M.; Satoh, N.; Del Genio, A. D.; Barbara, J.; Sanchez-Lavega, A.; Hueso, R.; García-Melendo, E.; Simon-Miller, A. A.

    2010-12-01

    Cloud tracking has been the primary method of measuring wind speeds in planetary atmospheres through Earth- and space- based remote sensing. Latest developments of automated feature tracking software are able to harvest thousands of wind vectors out of a sequence of high-resolution images acquired with an appropriate temporal separation. However, unlike satellite-based cloud-tracking measurements of Earth, these planetary measurements cannot easily be validated against in-situ data, which makes the interpretation difficult when different cloud-tracking schemes do not agree on their results. To address the issue of data validation, we run multiple automated cloud-tracking software independently developed at multiple institutions on synthetic wind data generated using a General Circulation Model. Our simulations calculate the advection of tracer distributions to represent cloud motions as done by Sayanagi and Showman (2007, Icarus 187, p520-539). The motions of tracers are measured using cloud-tracking software to derive wind vector fields, which will be compared against the model "truth." We test the performance of cloud-tracking software for different wind scenarios. Our first test wind field contains a simple zonal jet. The second test scenario is a large vortex like Jupiter’s Great Red Spot. The third test case has waves propagating alongside a zonal jet. We compare the results returned from different cloud-tracking schemes and discuss what approaches work better at measuring winds. In addition to verifying the wind vector field measurements, we also address the accuracy and validity of eddy momentum flux measurements by tracking clouds. The difficulties of such measurements are discussed by Salyk et al. (2006, Icarus 185, p430-442), and we re-examine the issue using our synthetic wind data. From our experiments, we aim to establish a standard benchmark of cloud tracking measurements for planetary mission applications.

  16. Aerosol-cloud interactions in ship tracks using Terra MODIS/MISR

    NASA Astrophysics Data System (ADS)

    Chen, Yi-Chun; Christensen, Matthew W.; Diner, David J.; Garay, Michael J.

    2015-04-01

    Simultaneous ship track observations from Terra Moderate Resolution Imaging Spectroradiometer (MODIS) and Multiangle Imaging Spectroradiometer (MISR) have been compiled to investigate how ship-injected aerosols affect marine warm boundary layer clouds for different cloud types and environmental conditions. By taking advantage of the high spatial resolution multiangle observations available from MISR, we utilized the retrieved cloud albedo, cloud top height, and cloud motion vectors to examine cloud property responses in ship-polluted and nearby unpolluted clouds. The strength of the cloud albedo response to increased aerosol level is primarily dependent on cloud cell structure, dryness of the free troposphere, and boundary layer depth, corroborating a previous study by Chen et al. (2012) where A-Train satellite data were utilized. Under open cell cloud structure the cloud properties are more susceptible to aerosol perturbations as compared to closed cells. Aerosol plumes caused an increase in liquid water amount (+38%), cloud top height (+13%), and cloud albedo (+49%) for open cell clouds, whereas for closed cell clouds, little change in cloud properties was observed. Further capitalizing on MISR's unique capabilities, the MISR cross-track cloud speed was used to derive cloud top divergence. Statistically averaging the results from the identified plume segments to reduce random noise, we found evidence of cloud top divergence in the ship-polluted clouds, whereas the nearby unpolluted clouds showed cloud top convergence, providing observational evidence of a change in local mesoscale circulation associated with enhanced aerosols. Furthermore, open cell polluted clouds revealed stronger cloud top divergence as compared to closed cell clouds, consistent with different dynamical mechanisms driving their responses. These results suggest that detailed cloud responses, classified by cloud type and environmental conditions, must be accounted for in global climate modeling

  17. ARM - Midlatitude Continental Convective Clouds Experiment (MC3E): Multi-Frequency Profilers, Vertical Air Motion (williams-vertair)

    DOE Data Explorer

    Williams, Christopher; Jensen, Mike

    2012-11-06

    This data was collected by the NOAA 449-MHz and 2.8-GHz profilers in support of the Department of Energy (DOE) and NASA sponsored Mid-latitude Continental Convective Cloud Experiment (MC3E). The profiling radars were deployed in Northern Oklahoma at the DOE Atmospheric Radiation Mission (ARM) Southern Great Plans (SGP) Central Facility from 22 April through 6 June 2011. NOAA deployed three instruments: a Parsivel disdrometer, a 2.8-GHz profiler, and a 449-MHz profiler. The parasivel provided surface estimates of the raindrop size distribution and is the reference used to absolutely calibrate the 2.8 GHz profiler. The 2.8-GHz profiler provided unattenuated reflectivity profiles of the precipitation. The 449-MHz profiler provided estimates of the vertical air motion during precipitation from near the surface to just below the freezing level. By using the combination of 2.8-GHz and 449-MHz profiler observations, vertical profiles of raindrop size distributions can be retrieved. The profilers are often reference by their frequency band: the 2.8-GHz profiler operates in the S-band and the 449-MHz profiler operates in the UHF band. The raw observations are available as well as calibrated spectra and moments. This document describes how the instruments were deployed, how the data was collected, and the format of the archived data.

  18. Influence of the cosmological constant on the motion of Magellanic Clouds in the gravitational field of Milky Way

    SciTech Connect

    Stuchlík, Zdeněk; Schee, Jan E-mail: jan.schee@fpf.slu.cz

    2011-09-01

    Using the pseudo-Newtonian (PN) potential reflecting properties of the Schwarz-schild-de Sitter spacetime, we estimate the influence of the repulsive cosmological constant Λ ∼ 1.3 × 10{sup −56}cm{sup −2} implied by recent cosmological tests onto the motion of both Small and Large Magellanic Clouds (SMC and LMC) in the gravitational field of the Milky Way. Considering detailed modelling of the gravitational field of the Galaxy disc, bulge and cold dark matter halo, the trajectories of SMC and LMC constructed for the PN potential with the cosmological constant are confronted to those given for Λ = 0. In the realistic model of the extended cold dark matter halo its edge and related total mass are taken at typical values reflecting recent diversity in the total Galaxy mass estimates. In all cases, strong influence of the cosmological constant, on 10% level or higher, has been found for motion of both SMC and LMC. Inside the halo, the Newtonian part of the PN potential is exact enough, while outside the halo the PN potential can give relevant relativistic corrections. The role of the cosmological constant is most conspicuous when binding mass is estimated for the satellite galaxies. We have found a strong influence of cosmic repulsion on the total binding mass for both galaxies. For SMC there is the binding mass M{sub SMC}{sup Λ=0} = 7.07 × 10{sup 11}M{sub ⨀} and M{sub SMC}{sup Λ>0} = 8.61 × 10{sup 11}M{sub ⨀}, while even much higher increase is found for LMC, where M{sub LMC}{sup Λ=0} = 1.50 × 10{sup 12}M{sub ⨀} and M{sub LMC}{sup Λ} {sup >0} = 2.21 × 10{sup 12}M{sub ⨀}, putting serious doubts on the possibility that the LMC is bounded by the Milky Way. However, the estimates of binding masses are strongly influenced by initial velocity of SMC and LMC; we took the values inferred for the IAU MW rotation velocity ∼ 220 km/s. Our results indicate very important role of the cosmic repulsion in the motion of interacting galaxies, clearly

  19. MISR Level 3 Albedo and Cloud Versioning

    Atmospheric Science Data Center

    2016-09-07

    ... 2:  CLOUD - Wind Vectors, Height Histogram Stage 1:  ALBEDO - Expansive, Restrictive and Local Albedo (except over snow and ... Stage 2 CLOUD - Height Histogram Stage 1 CLOUD - Wind Vectors Stage 1 ALBEDO - Expansive and Restrictive ...

  20. Aerosol-Cloud Interactions in Ship Tracks Using Terra MODIS/MISR

    NASA Astrophysics Data System (ADS)

    Chen, Y. C.; Christensen, M.; Diner, D. J.; Garay, M. J.; Nelson, D. L.

    2014-12-01

    Simultaneous ship track observations from Terra Moderate Resolution Imaging Spectroradiometer (MODIS) and Multi-angle Imaging SpectroRadiometer (MISR) have been compiled to investigate how ship-injected aerosols affect marine warm boundary layer clouds under different cloud types and environmental conditions. Taking advantage of the high spatial resolution multiangle observations uniquely available from MISR, we utilized the retrieved cloud albedo, cloud top height, and cloud motion vectors to examine the cloud property responses in ship-polluted and nearby unpolluted clouds. The strength of cloud albedo response to increased aerosol level is primarily dependent on cloud cell structure, dryness of the free troposphere, and boundary layer depth, corroborating a previous study by Chen et al. (2012) where A-Train satellite data were applied. Under open cell cloud structure, the cloud properties are more susceptible to aerosol perturbations as compared to closed cells. Aerosol plumes caused an increase in liquid water amount (+27%), cloud top height (+11%), and cloud albedo (+40%) for open cell clouds, whereas under closed cell clouds, little changes in cloud properties were observed. Further capitalizing on MISR's unique capabilities, the MISR cross-track cloud speed has been used to derive cloud top divergence. Statistically averaging the results from many plume segments to reduce random noise, we have found that in ship-polluted clouds there is stronger cloud top divergence, and in nearby unpolluted clouds, convergence occurs and leads to downdrafts, providing observational evidence for cloud top entrainment feedback. These results suggest that detailed cloud responses, classified by cloud type and environmental conditions, must be accounted for in global climate modeling studies to reduce uncertainties of aerosol indirect forcing. Reference: Chen, Y.-C. et al. Occurrence of lower cloud albedo in ship tracks, Atmos. Chem. Phys., 12, 8223-8235, doi:10.5194/acp-12

  1. Investigating Plasma Motion of Magnetic Clouds at 1 AU through a Velocity-modified Cylindrical Force-free Flux Rope Model

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Shen, C.; Liu, R.; Zhou, Z.

    2014-12-01

    Magnetic clouds (MCs) are the interplanetary counterparts of coronal mass ejections (CMEs). Due to the very low value of Can't connect to bucket.int.confex.com:4201 (Connection refused) LWP::Protocol::http::Socket: connect: Connection refused at /usr/local/lib/perl5/site_perl/5.8.8/LWP/Protocol/http.pm line 51. in MCs, they are believed to be in a nearly force-free state and therefore are able to be modeled by a cylindrical force-free flux rope. However, the force-free state only describes the magnetic field topology but not the plasma motion of a MC. For a MC propagating in interplanetary space, the global plasma motion has three possible components: linear propagating motion of a MC away from the Sun, expanding motion and circular motion with respect to the axis of the MC. By assuming the quasi-steady evolution and self-similar expansion, we introduced the three-component motion into the cylindrical force-free flux rope model, and developed a velocity-modified model. Then we applied the model to 73 MCs observed by Wind spacecraft to investigate the properties of the plasma motion of MCs. It is found that (1) some MCs did not propagate along the Sun-Earth line, suggesting the direct evidence of the CME's deflected propagation and/or rotation in interplanetary space, (2) the expansion speed is correlated with the radial propagation speed and 62%/17% of MCs underwent a under/over-expansion at 1 AU, and (3) the circular motion does exists though it is only on the order of 10 km s-1. These findings advance our understanding of the MC's properties at 1 AU as well as the dynamic evolution of CMEs from the Sun to interplanetary space.

  2. Implementation of a state of the art automated system for the production of cloud/water vapor motion winds from geostationary satellites

    NASA Technical Reports Server (NTRS)

    Velden, Christopher

    1995-01-01

    The research objectives in this proposal were part of a continuing program at UW-CIMSS to develop and refine an automated geostationary satellite winds processing system which can be utilized in both research and operational environments. The majority of the originally proposed tasks were successfully accomplished, and in some cases the progress exceeded the original goals. Much of the research and development supported by this grant resulted in upgrades and modifications to the existing automated satellite winds tracking algorithm. These modifications were put to the test through case study demonstrations and numerical model impact studies. After being successfully demonstrated, the modifications and upgrades were implemented into the NESDIS algorithms in Washington DC, and have become part of the operational support. A major focus of the research supported under this grant attended to the continued development of water vapor tracked winds from geostationary observations. The fully automated UW-CIMSS tracking algorithm has been tuned to provide complete upper-tropospheric coverage from this data source, with data set quality close to that of operational cloud motion winds. Multispectral water vapor observations were collected and processed from several different geostationary satellites. The tracking and quality control algorithms were tuned and refined based on ground-truth comparisons and case studies involving impact on numerical model analyses and forecasts. The results have shown the water vapor motion winds are of good quality, complement the cloud motion wind data, and can have a positive impact in NWP on many meteorological scales.

  3. Implementation of a state of the art automated system for the production of cloud/water vapor motion winds from geostationary satellites

    NASA Technical Reports Server (NTRS)

    Velden, Christopher S.

    1994-01-01

    The thrust of the proposed effort under this contract is aimed at improving techniques to track water vapor data in sequences of imagery from geostationary satellites. In regards to this task, significant testing, evaluation, and progress was accomplished during this period. Sets of winds derived from Meteosat data were routinely produced during Atlantic hurricane events in the 1993 season. These wind sets were delivered via Internet in real time to the Hurricane Research Division in Miami for their evaluation in a track forecast model. For eighteen cases in which 72-hour forecasts were produced, thirteen resulted in track forecast improvements (some quite significant). In addition, quality-controlled Meteosat water vapor winds produced by NESDIS were validated against rawinsondes, yielding an 8 m/s RMS. This figure is comparable to upper-level cloud drift wind accuracies. Given the complementary horizontal coverage in cloud-free areas, we believe that water vapor vectors can supplement cloud-drift wind information to provide good full-disk coverage of the upper tropospheric flow. The impact of these winds on numerical analysis and forecasts will be tested in the next reporting period.

  4. Predicting and validating the motion of an ash cloud during the 2006 eruption of Mount Augustine volcano

    USGS Publications Warehouse

    Collins, Richard L.; Fochesatto, Javier; Sassen, Kenneth; Webley, Peter W.; Atkinson, David E.; Dean, Kenneson G.; Cahill, Catherine F.; Mizutani, Kohei

    2007-01-01

    On 11 January 2006, Mount Augustine volcano in southern Alaska began erupting after 20- year repose. The Anchorage Forecast Office of the National Weather Service (NWS) issued an advisory on 28 January for Kodiak City. On 31 January, Alaska Airlines cancelled all flights to and from Anchorage after multiple advisories from the NWS for Anchorage and the surrounding region. The Alaska Volcano Observatory (AVO) had reported the onset of the continuous eruption. AVO monitors the approximately 100 active volcanoes in the Northern Pacific. Ash clouds from these volcanoes can cause serious damage to an aircraft and pose a serious threat to the local communities, and to transcontinental air traffic throughout the Arctic and sub-Arctic region. Within AVO, a dispersion model has been developed to track the dispersion of volcanic ash clouds. The model, Puff, was used operational by AVO during the Augustine eruptive period. Here, we examine the dispersion of a volcanic ash (or aerosol) cloud from Mount Augustine across Alaska from 29 January through the 2 February 2006. We present the synoptic meteorology, the Puff predictions, and measurements from aerosol samplers, laser radar (or lidar) systems, and satellites. Aerosol samplers revealed the presence of volcanic aerosols at the surface at sites where Puff predicted the ash clouds movement. Remote sensing satellite data showed the development of the ash cloud in close proximity to the volcano consistent with the Puff predictions. Two lidars showed the presence of volcanic aerosol with consistent characteristics aloft over Alaska and were capable of detecting the aerosol, even in the presence of scattered clouds and where the ash cloud is too thin/disperse to be detected by remote sensing satellite data. The lidar measurements revealed the different trajectories of ash consistent with the Puff predictions. Dispersion models provide a forecast of volcanic ash cloud movement that might be undetectable by any other means but are

  5. HST Astrometry in the 30 Doradus Region: Measuring Proper Motions of Individual Stars in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Platais, Imants; van der Marel, Roeland P.; Lennon, Daniel J.; Anderson, Jay; Bellini, Andrea; Sabbi, Elena; Sana, Hugues; Bedin, Luigi R.

    2015-09-01

    We present measurements of positions and relative proper motions in the 30 Doradus region of the LMC. We detail the construction of a single-epoch astrometric reference frame, based on specially designed observations obtained with the two main imaging instruments Advanced Camera for Surveys/Wide Field Channel and Wide Field Camera 3/UVIS on board the Hubble Space Telescope (HST). Internal comparisons indicate a sub milliarcsecond (mas) precision in the positions and the presence of semi-periodic systematics with a mean amplitude of ˜0.8 mas. We combined these observations with numerous archival images taken with Wide Field Planetary Camera 2 and spanning 17 years. The precision of the resulting proper motions for well-measured stars around the massive cluster Radcliffe 136 (R136) can be as good as ˜20 μas yr-1, although the true accuracy of proper motions is generally lower due to the residual systematic errors. The observed proper-motion dispersion for our highest-quality measurements is ˜0.1 mas yr-1. Our catalog of positions and proper motions contains 86,590 stars down to V ˜ 25 and over a total area of ˜70 square arcmin. We examined the proper motions of 105 relatively bright stars and identified a total of six candidate runaway stars. We are able to tentatively confirm the runaway status of star VFTS 285, consistent with the findings from line of sight velocities, and to show that this star has likely been ejected from R136. This study demonstrates that with HST it is now possible to reliably measure proper motions of individual stars in the nearest dwarf galaxies such as the LMC.

  6. MISR Level 2 TOA/Cloud Stereo parameters (MIL2TCST_V2)

    NASA Technical Reports Server (NTRS)

    Diner, David J. (Principal Investigator)

    The MISR Top-of-Atmosphere (TOA)/Cloud Stereo geophysical parameters include stereoscopically-derived cloud motion vectors (winds), cloud-top heights, and an accompanying cloud mask. The Stereo product geophysical parameters include a stereoscopically-derived cloud mask and cloud height on a 1.1 km grid. It also includes cloud motion vectors on a 70.4 km grid. The three types of stereo heights are: the BestWind heights are only calculated for those regions where the associated wind vectors passed the quality tests. Therefore, they have sparse coverage but since the wind correction is included, these contain our 'best guess' as to what the true heights are. The WithoutWind heights are calculated assuming a constant wind vector of zero. They have almost complete coverage and therefore form a nice 'pretty picture' of the relative cloud heights over small areas. The RawWind heights are a diagnostic product as they are calculated using all available wind vectors (even the bad ones). It is therefore recommended that one only use the Best and Without wind products. It is important to remember that the stereo matchers pick up the layer of maximum contrast, which is not necessarily the same as the highest cloud so all the stereo heights are keyed to this level of maximum contrast. Therefore, higher and thinner cirrus layers may not be detected by any of the height fields. [Temporal_Coverage: Start_Date=2000-02-24; Stop_Date=] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Latitude_Resolution=1.1 km; Longitude_Resolution=1.1 km; Temporal_Resolution=about 15 orbits/day].

  7. Vibration analysis of vector piezoresponse force microscopy with coupled flexural-longitudinal and lateral-torsional motions

    NASA Astrophysics Data System (ADS)

    Salehi-Khojin, Amin; Jalili, Nader; Nima Mahmoodi, S.

    2009-05-01

    Piezoresponse force microscopy (PFM) has evolved into a useful tool for measurement of local properties of piezoelectric materials with great potential in applications such as data storage, ferroelectric lithography and nonvolatile memories. In order to utilize PFM for low dimensional materials characterization, a comprehensive analytical modeling based on the coupled motion of PFM in all three directions is proposed. In this respect, the mechanical properties of sample are divided into viscoelastic and piezoelectric parts. The viscoelastic part is modeled as a spring and damper in the longitudinal, transversal and lateral directions, while the piezoelectric part is replaced with resistive forces acting at the end of microcantilever. It is shown that there is a geometrical coupling between flexural-longitudinal and lateral-torsional vibrations of microcantilever used in PFM. Moreover, assuming a general friction between tip and sample, additional coupling effect is also taken into account. Through an energy-based approach, it is seen that the PFM system can be governed by a set of coupled partial differential equations along with nonhomogeneous and coupled boundary conditions. A general formulation is then derived for the mode shape, frequency response, and state-space representation of system. Numerical simulations indicate that mode shapes, natural frequencies and time responses of microcantilever beam are heavily dependent on the viscoelastic and piezoelectric properties of the samples. Moreover, the results demonstrate that utilizing only transversal vibration is not a valid strategy for quantifying mechanical properties of materials with arbitrary crystallographic orientation. Hence, the proposed model with the built-in coupling effects can be a key development for acquiring precise measurements.

  8. Impact of assimilation of INSAT-3D retrieved atmospheric motion vectors on short-range forecast of summer monsoon 2014 over the South Asian region

    NASA Astrophysics Data System (ADS)

    Kumar, Prashant; Deb, Sanjib K.; Kishtawal, C. M.; Pal, P. K.

    2016-01-01

    The Weather Research and Forecasting (WRF) model and its three-dimensional variational data assimilation system are used in this study to assimilate the INSAT-3D, a recently launched Indian geostationary meteorological satellite derived from atmospheric motion vectors (AMVs) over the South Asian region during peak Indian summer monsoon month (i.e., July 2014). A total of four experiments were performed daily with and without assimilation of INSAT-3D-derived AMVs and the other AMVs available through Global Telecommunication System (GTS) for the entire month of July 2014. Before assimilating these newly derived INSAT-3D AMVs in the numerical model, a preliminary evaluation of these AMVs is performed with National Centers for Environmental Prediction (NCEP) final model analyses. The preliminary validation results show that root-mean-square vector difference (RMSVD) for INSAT-3D AMVs is ˜3.95, 6.66, and 5.65 ms-1 at low, mid, and high levels, respectively, and slightly more RMSVDs are noticed in GTS AMVs (˜4.0, 8.01, and 6.43 ms-1 at low, mid, and high levels, respectively). The assimilation of AMVs has improved the WRF model of produced wind speed, temperature, and moisture analyses as well as subsequent model forecasts over the Indian Ocean, Arabian Sea, Australia, and South Africa. Slightly more improvements are noticed in the experiment where only the INSAT-3D AMVs are assimilated compared to the experiment where only GTS AMVs are assimilated. The results also show improvement in rainfall predictions over the Indian region after AMV assimilation. Overall, the assimilation of INSAT-3D AMVs improved the WRF model short-range predictions over the South Asian region as compared to control experiments.

  9. On the accuracy of approximation of motion of a small celestial body by intermediate perturbed orbits calculated on the basis of three position vectors and three observations

    NASA Astrophysics Data System (ADS)

    Shefer, V. A.; Shefer, O. V.

    2016-05-01

    Intermediate perturbed orbits, which were proposed earlier by the first author and are calculated based on three position vectors and three measurements of angular coordinates of a small celestial body, are examined. Provided that the reference time interval encompassing the measurements is short, these orbits are close in the accuracy of approximation of actual motion to an orbit with fourth-order tangency. The shorter the reference time interval is, the better is the approximation. The laws of variation of the errors of methods for constructing such intermediate orbits with the length of the reference time interval are formulated. According to these laws, the rate of convergence of the methods to an exact solution in the process of shortening of the reference time interval is, in general, three orders of magnitude higher than that of conventional methods relying on an unperturbed Keplerian orbit. The considered orbits are among the most accurate of their class that is defined by the order of tangency. The obtained theoretical results are verified by numerical experiments on determining the orbit of 99942 Apophis.

  10. Climatology of Vertical Air Motion During Rainfall in Niamey, Niger and Black Forest, Germany using an Innovative Cloud Radar Retrieval Technique

    NASA Astrophysics Data System (ADS)

    Luke, E. P.; Giangrande, S. E.; Kollias, P.

    2008-12-01

    In recent years, the DOE Atmospheric Radiation Measurement (ARM) program has deployed its ARM Mobile Facility (AMF) to collect continuous measurements in several climatologically distinct locations, including a year-long stay in Niamey, Niger and eight months in Germany's Black Forest. The AMF includes a vertically pointing 95 GHz cloud radar, a tool of choice for profiling non-precipitating clouds at high spatial and temporal resolutions, but commonly considered poorly suited to the quantitative study of precipitation, due in large part to attenuation. However, an innovative technique first explored by Lhermitte in the late 1980s, and subsequently by others, sidesteps much of the quantitative uncertainty imposed by attenuation by exploiting non-Rayleigh resonance effects of scattering from raindrops at 95 GHz. Given a modest range of suitable drop sizes, non-Rayleigh resonances appear as distinct peaks and valleys in Doppler spectra, which once identified, can be directly mapped to known drop sizes by Mie theory. Although attenuation in rain at 95 GHz is substantial, key to the technique is that all non-Rayleigh peaks and valleys in a given Doppler spectrum are affected equally, preserving their relative positions and magnitudes (barring feature extinction). Vertical air motion is retrieved very accurately by taking the difference between the measured Doppler velocity of a resonance feature (usually the first valley) and the known terminal velocity of its associated drop size. We have achieved promising retrieval accuracies at spatial and temporal resolutions of 30 meters and 2 seconds. Here we present lessons learned when the retrieval technique is automated and applied to measurements taken in rain over the full durations of the Niamey and Black Forest AMF deployments, comparing vertical air velocity patterns of monsoonal precipitation over the African desert with those of the orographically influenced precipitation in Germany's mountains.

  11. Discovering hierarchical motion structure.

    PubMed

    Gershman, Samuel J; Tenenbaum, Joshua B; Jäkel, Frank

    2016-09-01

    Scenes filled with moving objects are often hierarchically organized: the motion of a migrating goose is nested within the flight pattern of its flock, the motion of a car is nested within the traffic pattern of other cars on the road, the motion of body parts are nested in the motion of the body. Humans perceive hierarchical structure even in stimuli with two or three moving dots. An influential theory of hierarchical motion perception holds that the visual system performs a "vector analysis" of moving objects, decomposing them into common and relative motions. However, this theory does not specify how to resolve ambiguity when a scene admits more than one vector analysis. We describe a Bayesian theory of vector analysis and show that it can account for classic results from dot motion experiments, as well as new experimental data. Our theory takes a step towards understanding how moving scenes are parsed into objects. PMID:25818905

  12. Short-interval SMS wind vector determinations for a severe local storms area

    NASA Technical Reports Server (NTRS)

    Peslen, C. A.

    1980-01-01

    Short-interval SMS-2 visible digital image data are used to derive wind vectors from cloud tracking on time-lapsed sequences of geosynchronous satellite images. The cloud tracking areas are located in the Central Plains, where on May 6, 1975 hail-producing thunderstorms occurred ahead of a well defined dry line. Cloud tracking is performed on the Goddard Space Flight Center Atmospheric and Oceanographic Information Processing System. Lower tropospheric cumulus tracers are selected with the assistance of a cloud-top height algorithm. Divergence is derived from the cloud motions using a modified Cressman (1959) objective analysis technique which is designed to organize irregularly spaced wind vectors into uniformly gridded wind fields. The results demonstrate the feasibility of using satellite-derived wind vectors and their associated divergence fields in describing the conditions preceding severe local storm development. For this case, an area of convergence appeared ahead of the dry line and coincided with the developing area of severe weather. The magnitude of the maximum convergence varied between -10 to the -5th and -10 to the -14th per sec. The number of satellite-derived wind vectors which were required to describe conditions of the low-level atmosphere was adequate before numerous cumulonimbus cells formed. This technique is limited in areas of advanced convection.

  13. Closed Large Cell Clouds

    Atmospheric Science Data Center

    2013-04-19

    article title:  Closed Large Cell Clouds in the South Pacific     ... unperturbed by cyclonic or frontal activity. When the cell centers are cloudy and the main sinking motion is concentrated at cell ...

  14. Automatic cloud tracking applied to GOES and Meteosat observations

    NASA Technical Reports Server (NTRS)

    Endlich, R. M.; Wolf, D. E.

    1981-01-01

    An improved automatic processing method for the tracking of cloud motions as revealed by satellite imagery is presented and applications of the method to GOES observations of Hurricane Eloise and Meteosat water vapor and infrared data are presented. The method is shown to involve steps of picture smoothing, target selection and the calculation of cloud motion vectors by the matching of a group at a given time with its best likeness at a later time, or by a cross-correlation computation. Cloud motion computations can be made in as many as four separate layers simultaneously. For data of 4 and 8 km resolution in the eye of Hurricane Eloise, the automatic system is found to provide results comparable in accuracy and coverage to those obtained by NASA analysts using the Atmospheric and Oceanographic Information Processing System, with results obtained by the pattern recognition and cross correlation computations differing by only fractions of a pixel. For Meteosat water vapor data from the tropics and midlatitudes, the automatic motion computations are found to be reliable only in areas where the water vapor fields contained small-scale structure, although excellent results are obtained using Meteosat IR data in the same regions. The automatic method thus appears to be competitive in accuracy and coverage with motion determination by human analysts.

  15. The Mesoscale and Microscale Structure and Organization of Clouds and Precipitation in Midlatitude Cyclones. III: Air Motions and Precipitation Growth in a Warm-Frontal Rainband.

    NASA Astrophysics Data System (ADS)

    Houze, Robert A., Jr.; Rutledge, Steven A.; Matejka, Thomas J.; Hobbs, Peter V.

    1981-03-01

    Doppler radar data and airborne cloud microphysical measurements obtained in the CYCLES PROJECT indicate that a warm-frontal rainband in an extratropical cyclone was characterized by a precipitation process in which clouds at low levels were enhanced by a mesoscale updraft. Ice particles, apparently formed in shallow convective cells aloft and then drifted downward, undergoing aggregation just above the melting layer. This study demonstrates the crucial role of the low-level mesoscale updraft in condensing a sufficient amount of cloud water for particles to accrete as they fell through the lower portion of the frontal cloud.

  16. Vertical Velocity Measurements in Warm Stratiform Clouds

    NASA Astrophysics Data System (ADS)

    Luke, E. P.; Kollias, P.

    2013-12-01

    Measurements of vertical air motion in warm boundary layer clouds are key for quantitatively describing cloud-scale turbulence and for improving our understanding of cloud and drizzle microphysical processes. Recently, a new technique that produces seamless measurements of vertical air velocity in the cloud and sub-cloud layers for both drizzling and non-drizzling stratocumulus clouds has been developed. The technique combines radar Doppler spectra-based retrievals of vertical air motion in cloud and light drizzle conditions with a novel neural network analysis during heavily drizzling periods. Observations from Doppler lidars are used to characterize sub-cloud velocities and to evaluate the performance of the technique near the cloud base. The technique is applied to several cases of stratiform clouds observed by the ARM Mobile Facility during the Two-Column Aerosol Project (TCAP) campaign in Cape Cod. The observations clearly illustrate coupling of the sub-cloud and cloud layer turbulent structures.

  17. Cloud Front

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA02171 Cloud Front

    These clouds formed in the south polar region. The faintness of the cloud system likely indicates that these are mainly ice clouds, with relatively little dust content.

    Image information: VIS instrument. Latitude -86.7N, Longitude 212.3E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  18. Introducing Vectors.

    ERIC Educational Resources Information Center

    Roche, John

    1997-01-01

    Suggests an approach to teaching vectors that promotes active learning through challenging questions addressed to the class, as opposed to subtle explanations. Promotes introducing vector graphics with concrete examples, beginning with an explanation of the displacement vector. Also discusses artificial vectors, vector algebra, and unit vectors.…

  19. Mesoscale cloud phenomena observed by LANDSAT

    NASA Technical Reports Server (NTRS)

    Ormsby, J. P.

    1977-01-01

    Examples of certain mesoscale cloud features - jet cirrus, eddies/vortices, cloud banding, and wave clouds - were collected from LANDSAT imagery and placed into Mason's four groups of causes of cloud formation based on the mechanism of vertical motion which produces condensation. These groups are as follows: (1) layer clouds formed by widespread regular ascent; (2) layer clouds caused by irregular stirring motions; (3) convective clouds; and (4) clouds formed by orographic disturbances. These mechanisms explain general cloud formation. Once formed, other forces may play a role in the deformation of a cloud or cloud mass into unusual and unique meso- and microscale patterns. Each example presented is followed by a brief discussion describing the synoptic situation, and some inference into the formation and occurrence of the more salient features. No major attempt was made to discuss in detail the meteorological and topographic interplay producing these mesoscale features.

  20. A Sharper View of Venus:Strategies For Precise Cloud Tracking of Venus' Lower Cloud Deck

    NASA Astrophysics Data System (ADS)

    Tavenner, Tanya; Young, E. F.; Murphy, J.; Coyote, S.; Bullock, M.; Rafkin, S.

    2006-09-01

    We have observed the nightside of Venus at 2.3 microns using both IRTF on Mauna Kea and APO in New Mexico during the past two inferior conjuctions. Using IRTF we observed over a ten day span for 3-hours each day, which is sufficient to determine the major cloud motions. More recently by using both APO and IRTF we achieved a 5-hour temporal baseline each day over six days of observation. We see the lower cloud deck of Venus (48-52 km) backlit by 2.3 micron thermal radiation emanating from the surface and the lower atmosphere. These observations have allowed us to derive cloud-level wind speeds, and identify transient features in the observed Venusian wind field. We have adapted feature-tracking algorithms from several terrestrial remote sensing applications (e.g., Wu Inter. J. Remote Sensing, 1997, 2003; Bhat IEEE Trans. on PAMI, 20, 1998; Evans, IEEE Proc. of IGRSS, 1999) in order to track cloud movement. While this is still a work in progress, we show wind vector fields based on these algorithms and discuss their potential advantages and shortfalls. Our observations typically consist of many (a few thousand) short exposures of Venus during each twilight opportunity. These sequences lend themselves to image restoration processing by iterative blind deconvolution. We present restorations implemented using "IDAC" (Jefferies and Christou, ApJ, 415, 1993), a code that is distributed through the Center for Adaptive Optics at UC Santa Cruz. The use of IDAC has significantly increased the resolution of our ground based observations of Venus. This increases the accuracy of our wind speed measurements to the point were we can look for meridional motion. We will be presenting our most recent results and vector fields. This work supported by NASA's Infrared Telescope Facility and by the NASA Planetary Astronomy Program.

  1. Linear Clouds

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA03667 Linear Clouds

    These clouds are located near the edge of the south polar region. The cloud tops are the puffy white features in the bottom half of the image.

    Image information: VIS instrument. Latitude -80.1N, Longitude 52.1E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  2. Search Cloud

    MedlinePlus

    ... this page: https://medlineplus.gov/cloud.html Search Cloud To use the sharing features on this page, ... Top 110 zoster vaccine Share the MedlinePlus search cloud with your users by embedding our search cloud ...

  3. Search Cloud

    MedlinePlus

    ... www.nlm.nih.gov/medlineplus/cloud.html Search Cloud To use the sharing features on this page, please enable JavaScript. Share the MedlinePlus search cloud with your users by embedding our search cloud ...

  4. Static imaging of motion: motion texture

    NASA Astrophysics Data System (ADS)

    Arimura, Koichi

    1992-05-01

    This paper describes how motion segmentation can be achieved by analyzing of a single static image that is created from a series of picture frames. The key idea is motion imaging; in other words, motion is expressed in static images by integrating, frame after frame, the spatiotemporal fluctuations of the gradient gray level at each local area. This tends to create blurred or attached line images (images with lines that show the path of movement of an object through space) on moving objects. We call this 'motion texture'. We computed motion texture images based on the animation of a natural scene and on a number of computer synthesized animations containing groups of moving objects (random dots). Moreover, we applied two different texture analyses to the motion textured images for segmentation: a texture analysis based on the local homogeneity of gray level gradation in similarly textured regions and another based on the structural feature of gray level gradation in motion texture. Experiments showed that subjective visual impressions of segmentation were quite different for these animations. The texture segmentation described here successfully grouped moving objects coincident to subjective impressions. In our random dot animations, the density of the basic motion vectors extracted from each pair of successive frames was set at a constant to compensate for the dot grouping effect based on the vector density. The dot appearance period (lifetime) is varied across the animations. In a long lifetime random dot animation, region boundaries can be more clearly perceived than in a short one. The different impressions may be explained by analyzing the motion texture elements, but can not always be represented successfully using the motion vectors between two successive frames whose density is set at a constant between the animations with the different lifetime.

  5. A new perspective on the interstellar cloud surrounding the Sun from UV absorption line results

    NASA Astrophysics Data System (ADS)

    Gry, Cecile; Jenkins, Edward B.

    2015-01-01

    We offer a new, more inclusive, picture of the local interstellar medium, where it is composed of a single, monolithic cloud that surrounds the Sun in all directions. Our study of velocities based on Mg II and Fe II ultraviolet absorption lines indicates that the cloud has an average motion consistent with the velocity vector of gas impacting the heliosphere and does not behave like a rigid body: gas within the cloud is being differentially decelerated in the direction of motion, and the cloud is expanding in directions perpendicular to this flow, much like the squashing of a balloon. The outer boundary of the cloud is in average 10 pc away from us but is highly irregular, being only a few parsecs away in some directions, with possibly a few extensions up to 20 pc. Average H I volume densities vary between 0.03 and 0.1 cm3 over different sight lines. Metals appear to be significantly depleted onto grains, and there is a steady increase in this effect from the rear of the cloud to the apex of motion. There is no evidence that changes in the ionizing radiation influence the apparent abundances. Additional, secondary velocity components are detected in 60% of the sight lines. Almost all of them appear to be interior to the volume holding the gas that we identify with the main cloud. Half of the sight lines exhibit a secondary component moving at about - 7.2 km/s with respect to the main component, which may be the signature of an implosive shock propagating toward the cloud's interior.

  6. On the accuracy of approximation of a small celestial body motion using intermediate perturbed orbits calculated from two position vectors and three observations

    NASA Astrophysics Data System (ADS)

    Shefer, V. A.; Shefer, O. V.

    2015-01-01

    We examine intermediate perturbed orbits proposed by the first author previously, defined from the two position vectors and three angular coordinates of a small celestial body. It is shown theoretically, that at a small reference time interval covering the measurements the approximation accuracy of real movements by these orbits corresponds approximately to the third order of osculation. The smaller reference interval of time, the better this correspondence. Laws of variation of the methodical errors in constructing intermediate orbits subject to the length of reference time interval are deduced. According to these laws, the convergence rate of the methods to the exact solution (upon reducing the reference interval of time) is higher by two orders of magnitude than in the case of conventional methods using the Keplerian unperturbed orbit. The considered orbits are among the most accurate in set of orbits of their class determined by the order of osculation. The theoretical results are validated by numerical examples.

  7. Analytical study of the effects of the Low-Level Jet on moisture convergence and vertical motion fields at the Southern Great Plains Cloud and Radiation Testbed site

    SciTech Connect

    Bian, X.; Zhong, S.; Whiteman, C.D.; Stage, S.A.

    1996-04-01

    The Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) Cloud and Radiation Testbed (CART) is located in a region that is strongly affected by a prominent meteorological phenomenon--the Great Plains Low-Level Jet (LLJ). Observations have shown that the LLJ plays a vital role in spring and summertime cloud formation and precipitation over the Great Plains. An improved understanding of the LLJ characteristics and its impact on the environment is necessary for addressing the fundamental issue of development and testing of radiational transfer and cloud parameterization schemes for the general circulation models (GCMs) using data from the SGP CART site. A climatological analysis of the summertime LLJ over the SGP has been carried out using hourly observations from the National Oceanic and Atmospheric Administration (NOAA) Wind Profiler Demonstration Network and from the ARM June 1993 Intensive Observation Period (IOP). The hourly data provide an enhanced temporal and spatial resolution relative to earlier studies which used 6- and 12-hourly rawinsonde observations at fewer stations.

  8. Cloud Interactions

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Released 1 July 2004 The atmosphere of Mars is a dynamic system. Water-ice clouds, fog, and hazes can make imaging the surface from space difficult. Dust storms can grow from local disturbances to global sizes, through which imaging is impossible. Seasonal temperature changes are the usual drivers in cloud and dust storm development and growth.

    Eons of atmospheric dust storm activity has left its mark on the surface of Mars. Dust carried aloft by the wind has settled out on every available surface; sand dunes have been created and moved by centuries of wind; and the effect of continual sand-blasting has modified many regions of Mars, creating yardangs and other unusual surface forms.

    This image was acquired during mid-spring near the North Pole. The linear water-ice clouds are now regional in extent and often interact with neighboring cloud system, as seen in this image. The bottom of the image shows how the interaction can destroy the linear nature. While the surface is still visible through most of the clouds, there is evidence that dust is also starting to enter the atmosphere.

    Image information: VIS instrument. Latitude 68.4, Longitude 258.8 East (101.2 West). 38 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration

  9. Shape of fair weather clouds.

    PubMed

    Wang, Yong; Zocchi, Giovanni

    2010-03-19

    We introduce a model which accounts for the shape of cumulus clouds exclusively in terms of thermal plumes or thermals. The plumes are explicitly represented by a simple potential flow generated by singularities (sources and sinks) and are thus laminar, but with their motion create a field which supports the cloud. We compare this model with actual clouds by means of various shape descriptors including the fractal dimension, and find agreement. PMID:20366506

  10. A vector-dyadic development of the equations of motion for N-coupled flexible bodies and point masses. [spacecraft trajectories

    NASA Technical Reports Server (NTRS)

    Frisch, H. P.

    1975-01-01

    The equations of motion for a system of coupled flexible bodies, rigid bodies, point masses, and symmetric wheels were derived. The equations were cast into a partitioned matrix form in which certain partitions became nontrivial when the effects of flexibility were treated. The equations are shown to contract to the coupled rigid body equations or expand to the coupled flexible body equations all within the same basic framework. Furthermore, the coefficient matrix always has the computationally desirable property of symmetry. Making use of the derived equations, a comparison was made between the equations which described a flexible body model and those which described a rigid body model of the same elastic appendage attached to an arbitrary coupled body system. From the comparison, equivalence relations were developed which defined how the two modeling approaches described identical dynamic effects.

  11. Crater Clouds

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA06085 Crater Clouds

    The crater on the right side of this image is affecting the local wind regime. Note the bright line of clouds streaming off the north rim of the crater.

    Image information: VIS instrument. Latitude -78.8N, Longitude 320.0E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  12. Martian Clouds

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Released 28 June 2004 The atmosphere of Mars is a dynamic system. Water-ice clouds, fog, and hazes can make imaging the surface from space difficult. Dust storms can grow from local disturbances to global sizes, through which imaging is impossible. Seasonal temperature changes are the usual drivers in cloud and dust storm development and growth.

    Eons of atmospheric dust storm activity has left its mark on the surface of Mars. Dust carried aloft by the wind has settled out on every available surface; sand dunes have been created and moved by centuries of wind; and the effect of continual sand-blasting has modified many regions of Mars, creating yardangs and other unusual surface forms.

    This image was acquired during early spring near the North Pole. The linear 'ripples' are transparent water-ice clouds. This linear form is typical for polar clouds. The black regions on the margins of this image are areas of saturation caused by the build up of scattered light from the bright polar material during the long image exposure.

    Image information: VIS instrument. Latitude 68.1, Longitude 147.9 East (212.1 West). 38 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS

  13. Project Physics Reader 1, Concepts of Motion.

    ERIC Educational Resources Information Center

    Harvard Univ., Cambridge, MA. Harvard Project Physics.

    As a supplement to Project Physics Unit 1, 21 articles are presented in this reader. Concepts of motion are discussed under headings: motion, motion in words, representation of movement, introducing vectors, Galileo's discussion of projectile motion, Newton's laws of dynamics, the dynamics of a golf club, report on Tait's lecture on force, and bad…

  14. Optimal Exploitation of the Temporal and Spatial Resolution of SEVIRI for the Nowcasting of Clouds

    NASA Astrophysics Data System (ADS)

    Sirch, Tobias; Bugliaro, Luca

    2015-04-01

    Optimal Exploitation of the Temporal and Spatial Resolution of SEVIRI for the Nowcasting of Clouds An algorithm was developed to forecast the development of water and ice clouds for the successive 5-120 minutes separately using satellite data from SEVIRI (Spinning Enhanced Visible and Infrared Imager) aboard Meteosat Second Generation (MSG). In order to derive cloud cover, optical thickness and cloud top height of high ice clouds "The Cirrus Optical properties derived from CALIOP and SEVIRI during day and night" (COCS, Kox et al. [2014]) algorithm is applied. For the determination of the liquid water clouds the APICS ("Algorithm for the Physical Investigation of Clouds with SEVIRI", Bugliaro e al. [2011]) cloud algorithm is used, which provides cloud cover, optical thickness and effective radius. The forecast rests upon an optical flow method determining a motion vector field from two satellite images [Zinner et al., 2008.] With the aim of determining the ideal time separation of the satellite images that are used for the determination of the cloud motion vector field for every forecast horizon time the potential of the better temporal resolution of the Meteosat Rapid Scan Service (5 instead of 15 minutes repetition rate) has been investigated. Therefore for the period from March to June 2013 forecasts up to 4 hours in time steps of 5 min based on images separated by a time interval of 5 min, 10 min, 15 min, 30 min have been created. The results show that Rapid Scan data produces a small reduction of errors for a forecast horizon up to 30 minutes. For the following time steps forecasts generated with a time interval of 15 min should be used and for forecasts up to several hours computations with a time interval of 30 min provide the best results. For a better spatial resolution the HRV channel (High Resolution Visible, 1km instead of 3km maximum spatial resolution at the subsatellite point) has been integrated into the forecast. To detect clouds the difference of

  15. 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

  16. TURBULENCE DECAY AND CLOUD CORE RELAXATION IN MOLECULAR CLOUDS

    SciTech Connect

    Gao, Yang; Law, Chung K.; Xu, Haitao

    2015-02-01

    The turbulent motion within molecular clouds is a key factor controlling star formation. Turbulence supports molecular cloud cores from evolving to gravitational collapse and hence sets a lower bound on the size of molecular cloud cores in which star formation can occur. On the other hand, without a continuous external energy source maintaining the turbulence, such as in molecular clouds, the turbulence decays with an energy dissipation time comparable to the dynamic timescale of clouds, which could change the size limits obtained from Jean's criterion by assuming constant turbulence intensities. Here we adopt scaling relations of physical variables in decaying turbulence to analyze its specific effects on the formation of stars. We find that the decay of turbulence provides an additional approach for Jeans' criterion to be achieved, after which gravitational infall governs the motion of the cloud core. This epoch of turbulence decay is defined as cloud core relaxation. The existence of cloud core relaxation provides a more complete understanding of the effect of the competition between turbulence and gravity on the dynamics of molecular cloud cores and star formation.

  17. Enhanced motion coding in MC-EZBC

    NASA Astrophysics Data System (ADS)

    Chen, Junhua; Zhang, Wenjun; Wang, Yingkun

    2005-07-01

    Since hierarchical variable size block matching and bidirectional motion compensation are used in the motioncompensated embedded zero block coding (MC-EZBC), the motion information consists of motion vector quadtree map and motion vectors. In the conventional motion coding scheme, the quadtree structure is coded directly, the motion vector modes are coded with Huffman codes, and the motion vector differences are coded by an m-ary arithmetic coder with 0-order models. In this paper we propose a new motion coding scheme which uses an extension of the CABAC algorithm and new context modeling for quadtree structure coding and mode coding. In addition, we use a new scalable motion coding method which scales the motion vector quadtrees according to the rate-distortion slope of the tree nodes. Experimental results show that the new coding scheme increases the efficiency of the motion coding by more than 25%. The performance of the system is improved accordingly, especially in low bit rates. Moreover, with the scalable motion coding, the subjective and objective coding performance is further enhanced in low bit rate scenarios.

  18. Scanning Backscatter Lidar Observations for Characterizing 4-D Cloud and Aerosol Fields to Improve Radiative Transfer Parameterizations

    NASA Technical Reports Server (NTRS)

    Schwemmer, Geary K.; Miller, David O.

    2005-01-01

    dimensions. HARLIE was used in a ground-based configuration in several recent field campaigns. Principal data products include aerosol backscatter profiles, boundary layer heights, entrainment zone thickness, cloud fraction as a function of altitude and horizontal wind vector profiles based on correlating the motions of clouds and aerosol structures across portions of the scan. Comparisons will be made between various cloud detecting instruments to develop a baseline performance metric.

  19. Cloud absorption radiometer

    NASA Technical Reports Server (NTRS)

    Strange, M. G.

    1988-01-01

    The Cloud Absorption Radiometer (CAR) was developed to measure spectrally how light is scattered by clouds and to determine the single scattering albedo, important to meteorology and climate studies, with unprecedented accuracy. This measurement is based on ratios of downwelling to upwelling radiation within clouds, and so is not strongly dependent upon absolute radiometric calibration of the instrument. The CAR has a 5-inch aperture and 1 degree IFOV, and spatially scans in a plane orthogonal to the flight vector from the zenith to nadir at 1.7 revolutions per second. Incoming light is measured in 13 spectral bands, using silicon, germanium, and indium-antimonide detectors. Data from each channel is digitally recorded in flight with 10-bit (0.1 percent) resolution. The instrument incorporates several novel features. These features are briefly detailed.

  20. Vector Video

    NASA Astrophysics Data System (ADS)

    Taylor, David P.

    2001-01-01

    Vector addition is an important skill for introductory physics students to master. For years, I have used a fun example to introduce vector addition in my introductory physics classes based on one with which my high school physics teacher piqued my interest many years ago.

  1. Cloud Computing

    SciTech Connect

    Pete Beckman and Ian Foster

    2009-12-04

    Chicago Matters: Beyond Burnham (WTTW). Chicago has become a world center of "cloud computing." Argonne experts Pete Beckman and Ian Foster explain what "cloud computing" is and how you probably already use it on a daily basis.

  2. Arctic Clouds

    Atmospheric Science Data Center

    2013-04-19

    ...     View Larger Image Stratus clouds are common in the Arctic during the summer months, and are ... formats available at JPL August 23, 2000 - Stratus clouds help modulate the arctic climate. project:  ...

  3. Improved automatic estimation of winds at the cloud top of Venus using superposition of cross-correlation surfaces

    NASA Astrophysics Data System (ADS)

    Ikegawa, Shinichi; Horinouchi, Takeshi

    2016-06-01

    Accurate wind observation is a key to study atmospheric dynamics. A new automated cloud tracking method for the dayside of Venus is proposed and evaluated by using the ultraviolet images obtained by the Venus Monitoring Camera onboard the Venus Express orbiter. It uses multiple images obtained successively over a few hours. Cross-correlations are computed from the pair combinations of the images and are superposed to identify cloud advection. It is shown that the superposition improves the accuracy of velocity estimation and significantly reduces false pattern matches that cause large errors. Two methods to evaluate the accuracy of each of the obtained cloud motion vectors are proposed. One relies on the confidence bounds of cross-correlation with consideration of anisotropic cloud morphology. The other relies on the comparison of two independent estimations obtained by separating the successive images into two groups. The two evaluations can be combined to screen the results. It is shown that the accuracy of the screened vectors are very high to the equatorward of 30 degree, while it is relatively low at higher latitudes. Analysis of them supports the previously reported existence of day-to-day large-scale variability at the cloud deck of Venus, and it further suggests smaller-scale features. The product of this study is expected to advance the dynamics of venusian atmosphere.

  4. Analysis and forecast experiments incorporating satellite soundings and cloud and water vapor drift wind information

    NASA Technical Reports Server (NTRS)

    Goodman, Brian M.; Diak, George R.; Mills, Graham A.

    1986-01-01

    A system for assimilating conventional meteorological data and satellite-derived data in order to produce four-dimensional gridded data sets of the primary atmospheric variables used for updating limited area forecast models is described. The basic principles of a data assimilation scheme as proposed by Lorenc (1984) are discussed. The design of the system and its incremental assimilation cycles are schematically presented. The assimilation system was tested using radiosonde, buoy, VAS temperature, dew point, gradient wind data, cloud drift, and water vapor motion data. The rms vector errors for the data are analyzed.

  5. CubeSat Constellation Cloud Winds(C3Winds) A New Wind Observing System to Study Mesoscale Cloud Dynamics and Processes

    NASA Technical Reports Server (NTRS)

    Wu, D. L.; Kelly, M.A.; Yee, J.-H.; Boldt, J.; Demajistre, R.; Reynolds, E. L.; Tripoli, G. J.; Oman, L. D.; Prive, N.; Heidinger, A. K.; Wanzong, S. T.

    2016-01-01

    The CubeSat Constellation Cloud Winds (C3Winds) is a NASA Earth Venture Instrument (EV-I) concept with the primary objective to better understand mesoscale dynamics and their structures in severe weather systems. With potential catastrophic damage and loss of life, strong extratropical and tropical cyclones (ETCs and TCs) have profound three-dimensional impacts on the atmospheric dynamic and thermodynamic structures, producing complex cloud precipitation patterns, strong low-level winds, extensive tropopause folds, and intense stratosphere-troposphere exchange. Employing a compact, stereo IR-visible imaging technique from two formation-flying CubeSats, C3Winds seeks to measure and map high-resolution (2 km) cloud motion vectors (CMVs) and cloud geometric height (CGH) accurately by tracking cloud features within 5-15 min. Complementary to lidar wind observations from space, the high-resolution wind fields from C3Winds will allow detailed investigations on strong low-level wind formation in an occluded ETC development, structural variations of TC inner-core rotation, and impacts of tropopause folding events on tropospheric ozone and air quality. Together with scatterometer ocean surface winds, C3Winds will provide a more comprehensive depiction of atmosphere-boundary-layer dynamics and interactive processes. Built upon mature imaging technologies and long history of stereoscopic remote sensing, C3Winds provides an innovative, cost-effective solution to global wind observations with potential of increased diurnal sampling via CubeSat constellation.

  6. Multiscale Cloud System Modeling

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Moncrieff, Mitchell W.

    2009-01-01

    The central theme of this paper is to describe how cloud system resolving models (CRMs) of grid spacing approximately 1 km have been applied to various important problems in atmospheric science across a wide range of spatial and temporal scales and how these applications relate to other modeling approaches. A long-standing problem concerns the representation of organized precipitating convective cloud systems in weather and climate models. Since CRMs resolve the mesoscale to large scales of motion (i.e., 10 km to global) they explicitly address the cloud system problem. By explicitly representing organized convection, CRMs bypass restrictive assumptions associated with convective parameterization such as the scale gap between cumulus and large-scale motion. Dynamical models provide insight into the physical mechanisms involved with scale interaction and convective organization. Multiscale CRMs simulate convective cloud systems in computational domains up to global and have been applied in place of contemporary convective parameterizations in global models. Multiscale CRMs pose a new challenge for model validation, which is met in an integrated approach involving CRMs, operational prediction systems, observational measurements, and dynamical models in a new international project: the Year of Tropical Convection, which has an emphasis on organized tropical convection and its global effects.

  7. Cloning vector

    DOEpatents

    Guilfoyle, R.A.; Smith, L.M.

    1994-12-27

    A vector comprising a filamentous phage sequence containing a first copy of filamentous phage gene X and other sequences necessary for the phage to propagate is disclosed. The vector also contains a second copy of filamentous phage gene X downstream from a promoter capable of promoting transcription in a bacterial host. In a preferred form of the present invention, the filamentous phage is M13 and the vector additionally includes a restriction endonuclease site located in such a manner as to substantially inactivate the second gene X when a DNA sequence is inserted into the restriction site. 2 figures.

  8. Cloning vector

    DOEpatents

    Guilfoyle, Richard A.; Smith, Lloyd M.

    1994-01-01

    A vector comprising a filamentous phage sequence containing a first copy of filamentous phage gene X and other sequences necessary for the phage to propagate is disclosed. The vector also contains a second copy of filamentous phage gene X downstream from a promoter capable of promoting transcription in a bacterial host. In a preferred form of the present invention, the filamentous phage is M13 and the vector additionally includes a restriction endonuclease site located in such a manner as to substantially inactivate the second gene X when a DNA sequence is inserted into the restriction site.

  9. An Inexpensive Mechanical Model for Projectile Motion

    ERIC Educational Resources Information Center

    Kagan, David

    2011-01-01

    As experienced physicists, we see the beauty and simplicity of projectile motion. It is merely the superposition of uniform linear motion along the direction of the initial velocity vector and the downward motion due to the constant acceleration of gravity. We see the kinematic equations as just the mathematical machinery to perform the…

  10. Equivalent Vectors

    ERIC Educational Resources Information Center

    Levine, Robert

    2004-01-01

    The cross-product is a mathematical operation that is performed between two 3-dimensional vectors. The result is a vector that is orthogonal or perpendicular to both of them. Learning about this for the first time while taking Calculus-III, the class was taught that if AxB = AxC, it does not necessarily follow that B = C. This seemed baffling. The…

  11. Vector quantization

    NASA Technical Reports Server (NTRS)

    Gray, Robert M.

    1989-01-01

    During the past ten years Vector Quantization (VQ) has developed from a theoretical possibility promised by Shannon's source coding theorems into a powerful and competitive technique for speech and image coding and compression at medium to low bit rates. In this survey, the basic ideas behind the design of vector quantizers are sketched and some comments made on the state-of-the-art and current research efforts.

  12. Mesoscale wake clouds in Skylab pictures.

    NASA Technical Reports Server (NTRS)

    Fujita, T. T.; Tecson, J. J.

    1974-01-01

    The recognition of cloud patterns formed in the wake of orographic obstacles was investigated using pictures from Skylab, for the purpose of estimating atmospheric motions. The existence of ship-wake-type wave clouds in contrast to vortex sheets were revealed during examination of the pictures, and an attempt was made to characterize the pattern of waves as well as the transition between waves and vortices. Examples of mesoscale cloud patterns which were analyzed photogrammetrically and meteorologically are presented.

  13. EDITORIAL: Focus on Cloud Physics FOCUS ON CLOUD PHYSICS

    NASA Astrophysics Data System (ADS)

    Falkovich, Gregory; Malinowski, Szymon P.

    2008-07-01

    Cloud physics has for a long time been an important segment of atmospheric science. It is common knowledge that clouds are crucial for our understanding of weather and climate. Clouds are also interesting by themselves (not to mention that they are beautiful). Complexity is hidden behind the common picture of these beautiful and interesting objects. The typical school textbook definition that a cloud is 'a set of droplets or particles suspended in the atmosphere' is not adequate. Clouds are complicated phenomena in which dynamics, turbulence, microphysics, thermodynamics and radiative transfer interact on a wide range of scales, from sub-micron to kilometres. Some of these interactions are subtle and others are more straightforward. Large and small-scale motions lead to activation of cloud condensation nuclei, condensational growth and collisions; small changes in composition and concentration of atmospheric aerosol lead to significant differences in radiative properties of the clouds and influence rainfall formation. It is justified to look at a cloud as a composite, nonlinear system which involves many interactions and feedback. This system is actively linked into a web of atmospheric, oceanic and even cosmic interactions. Due to the complexity of the cloud system, present-day descriptions of clouds suffer from simplifications, inadequate parameterizations, and omissions. Sometimes the most fundamental physics hidden behind these simplifications and parameterizations is not known, and a wide scope of view can sometimes prevent a 'microscopic', deep insight into the detail. Only the expertise offered by scientists focused on particular elementary processes involved in this complicated pattern of interactions allows us to shape elements of the puzzle from which a general picture of clouds can be created. To be useful, every element of the puzzle must be shaped precisely. This often creates problems in communication between the sciences responsible for shaping

  14. Dynamics of Finite Dust Clouds in a Magnetized Anodic Plasma

    SciTech Connect

    Piel, A.; Pilch, I.; Trottenberg, T.; Koepke, M. E.

    2008-09-07

    The response to an external modulation voltage of small dust clouds confined in an anodic plasma is studied. Dust density waves are excited when the cloud is larger than a wavelength, whereas a sloshing and stretching motion is found for smaller clouds. The wave dispersion shows similarities with waveguide modes.

  15. ARM Data for Cloud Parameterization

    SciTech Connect

    Xu, Kuan-Man

    2006-10-02

    The PI's ARM investigation (DE-IA02-02ER633 18) developed a physically-based subgrid-scale saturation representation that fully considers the direct interactions of the parameterized subgrid-scale motions with subgrid-scale cloud microphysical and radiative processes. Major accomplishments under the support of that interagency agreement are summarized in this paper.

  16. The influence of transverse motion within an atomic gravimeter

    NASA Astrophysics Data System (ADS)

    Louchet-Chauvet, Anne; Farah, Tristan; Bodart, Quentin; Clairon, André; Landragin, Arnaud; Merlet, Sébastien; Pereira Dos Santos, Franck

    2011-06-01

    Limits on the long-term stability and accuracy of a second generation cold atom gravimeter are investigated. We demonstrate a measurement protocol based on four interleaved measurement configurations, which allows rejection of most of the systematic effects, but not those related to Coriolis acceleration and wave-front distortions. Both are related to the transverse motion of the atomic cloud. Carrying out measurements with opposite orientations with respect to the Earth's rotation vector direction allows us to separate the effects and correct for the Coriolis shift. Finally, measurements at different atomic temperatures are presented and analyzed. In particular, we show the difficulty of extrapolating these measurements to zero temperature, which is required in order to correct for the bias due to wave-front distortions.

  17. Cloud Control

    ERIC Educational Resources Information Center

    Ramaswami, Rama; Raths, David; Schaffhauser, Dian; Skelly, Jennifer

    2011-01-01

    For many IT shops, the cloud offers an opportunity not only to improve operations but also to align themselves more closely with their schools' strategic goals. The cloud is not a plug-and-play proposition, however--it is a complex, evolving landscape that demands one's full attention. Security, privacy, contracts, and contingency planning are all…

  18. Cloud Cover

    ERIC Educational Resources Information Center

    Schaffhauser, Dian

    2012-01-01

    This article features a major statewide initiative in North Carolina that is showing how a consortium model can minimize risks for districts and help them exploit the advantages of cloud computing. Edgecombe County Public Schools in Tarboro, North Carolina, intends to exploit a major cloud initiative being refined in the state and involving every…

  19. Cloud Control

    ERIC Educational Resources Information Center

    Weinstein, Margery

    2012-01-01

    Your learning curriculum needs a new technological platform, but you don't have the expertise or IT equipment to pull it off in-house. The answer is a learning system that exists online, "in the cloud," where learners can access it anywhere, anytime. For trainers, cloud-based coursework often means greater ease of instruction resulting in greater…

  20. Operational implications of a cloud model simulation of space shuttle exhaust clouds in different atmospheric conditions

    NASA Technical Reports Server (NTRS)

    Zak, J. A.

    1989-01-01

    A three-dimensional cloud model was used to characterize the dominant influence of the environment on the Space Shuttle exhaust cloud. The model was modified to accept the actual heat and moisture from rocket exhausts and deluge water as initial conditions. An upper-air sounding determined the ambient atmosphere in which the cloud would grow. The model was validated by comparing simulated clouds with observed clouds from four actual Shuttle launches. Results are discussed with operational weather forecasters in mind. The model successfully produced clouds with dimensions, rise, decay, liquid water contents, and vertical motion fields very similar to observed clouds whose dimensions were calculated from 16 mm film frames. Once validated, the model was used in a number of different atmospheric conditions ranging from very unstable to very stable. Wind shear strongly affected the appearance of both the ground cloud and vertical column cloud. The ambient low-level atmospheric moisture governed the amount of cloud water in model clouds. Some dry atmospheres produced little or no cloud water. An empirical forecast technique for Shuttle cloud rise is presented and differences between natural atmospheric convection and exhaust clouds are discussed.

  1. Lower mass limit of an evolving interstellar cloud and chemistry in an evolving oscillatory cloud

    NASA Technical Reports Server (NTRS)

    Tarafdar, S. P.

    1986-01-01

    Simultaneous solution of the equation of motion, equation of state and energy equation including heating and cooling processes for interstellar medium gives for a collapsing cloud a lower mass limit which is significantly smaller than the Jeans mass for the same initial density. The clouds with higher mass than this limiting mass collapse whereas clouds with smaller than critical mass pass through a maximum central density giving apparently similar clouds (i.e., same Av, size and central density) at two different phases of its evolution (i.e., with different life time). Preliminary results of chemistry in such an evolving oscillatory cloud show significant difference in abundances of some of the molecules in two physically similar clouds with different life times. The problems of depletion and short life time of evolving clouds appear to be less severe in such an oscillatory cloud.

  2. Diurnal polar motion

    NASA Technical Reports Server (NTRS)

    Mcclure, P.

    1973-01-01

    An analytical theory is developed to describe diurnal polar motion in the earth which arises as a forced response due to lunisolar torques and tidal deformation. Doodson's expansion of the tide generating potential is used to represent the lunisolar torques. Both the magnitudes and the rates of change of perturbations in the earth's inertia tensor are included in the dynamical equations for the polar motion so as to account for rotational and tidal deformation. It is found that in a deformable earth with Love's number k = 0.29, the angular momentum vector departs by as much as 20 cm from the rotation axis rather than remaining within 1 or 2 cm as it would in a rigid earth. This 20 cm separation is significant in the interpretation of submeter polar motion observations because it necessitates an additional coordinate transformation in order to remove what would otherwise be a 20 cm error source in the conversion between inertial and terrestrial reference systems.

  3. A cloud model simulation of space shuttle exhaust clouds in different atmospheric conditions

    NASA Technical Reports Server (NTRS)

    Chen, C.; Zak, J. A.

    1989-01-01

    A three-dimensional cloud model was used to characterize the dominant influence of the environment on the Space Shuttle exhaust cloud. The model was modified to accept the actual heat and moisture from rocket exhausts and deluge water as initial conditions. An upper-air sounding determined the ambient atmosphere in which the cloud could grow. The model was validated by comparing simulated clouds with observed clouds from four actual Shuttle launches. The model successfully produced clouds with dimensions, rise, decay, liquid water contents and vertical motion fields very similar to observed clouds whose dimensions were calculated from 16 mm film frames. Once validated, the model was used in a number of different atmospheric conditions ranging from very unstable to very stable. In moist, unstable atmospheres simulated clouds rose to about 3.5 km in the first 4 to 8 minutes then decayed. Liquid water contents ranged from 0.3 to 1.0 g kg-1 mixing ratios and vertical motions were from 2 to 10 ms-1. An inversion served both to reduce entrainment (and erosion) at the top and to prevent continued cloud rise. Even in the most unstable atmospheres, the ground cloud did not rise beyond 4 km and in stable atmospheres with strong low level inversions the cloud could be trapped below 500 m. Wind shear strongly affected the appearance of both the ground cloud and vertical column cloud. The ambient low-level atmospheric moisture governed the amount of cloud water in model clouds. Some dry atmospheres produced little or no cloud water. One case of a simulated TITAN rocket explosion is also discussed.

  4. Shapes of Bubbles and Drops in Motion.

    ERIC Educational Resources Information Center

    O'Connell, James

    2000-01-01

    Explains the shape distortions that take place in fluid packets (bubbles or drops) with steady flow motion by using the laws of Archimedes, Pascal, and Bernoulli rather than advanced vector calculus. (WRM)

  5. Zero-gravity cloud physics.

    NASA Technical Reports Server (NTRS)

    Hollinden, A. B.; Eaton, L. R.; Vaughan, W. W.

    1972-01-01

    The first results of an ongoing preliminary-concept and detailed-feasibility study of a zero-gravity earth-orbital cloud physics research facility are reviewed. Current planning and thinking are being shaped by two major conclusions of this study: (1) there is a strong requirement for and it is feasible to achieve important and significant research in a zero-gravity cloud physics facility; and (2) some very important experiments can be accomplished with 'off-the-shelf' type hardware by astronauts who have no cloud-physics background; the most complicated experiments may require sophisticated observation and motion subsystems and the astronaut may need graduate level cloud physics training; there is a large number of experiments whose complexity varies between these two extremes.

  6. A surface-towed vector magnetometer

    NASA Astrophysics Data System (ADS)

    Gee, J. S.; Cande, S. C.

    2002-07-01

    We have tested the feasibility of using a commercial motion sensor as a vector magnetometer that can be towed at normal survey speeds behind a research vessel. In contrast to previous studies using a shipboard mounted vector magnetometer, the towed system is essentially unaffected by the magnetization of the towing vessel. Results from a test deployment compare favorably with an earlier vector aeromagnetic survey, indicating that the towed instrument can resolve horizontal and vertical anomalies with amplitudes >30-50 nT. This instrument should be particularly useful in equatorial regions, where the vector anomalies are substantially greater than the corresponding total field anomalies.

  7. Plate motion

    SciTech Connect

    Gordon, R.G. )

    1991-01-01

    The motion of tectonic plates on the earth is characterized in a critical review of U.S. research from the period 1987-1990. Topics addressed include the NUVEL-1 global model of current plate motions, diffuse plate boundaries and the oceanic lithosphere, the relation between plate motions and distributed deformations, accelerations and the steadiness of plate motions, the distribution of current Pacific-North America motion across western North America and its margin, plate reconstructions and their uncertainties, hotspots, and plate dynamics. A comprehensive bibliography is provided. 126 refs.

  8. Ionization and expansion of barium clouds in the ionosphere

    NASA Technical Reports Server (NTRS)

    Ma, T.-Z.; Schunk, R. W.

    1993-01-01

    A recently envelope 3D model is used here to study the motion of the barium clouds released in the ionosphere, including the ionization stage. The ionization and the expansion of the barium clouds and the interaction between the clouds and the background ions are investigated using three simulations: a cloud without a directional velocity, a cloud with an initial velocity of 5 km/s across the B field, and a cloud with initial velocity components of 2 km/s both along and across the B field.

  9. Magnetohydrodynamic stability of broad line region clouds

    NASA Astrophysics Data System (ADS)

    Krause, Martin; Schartmann, Marc; Burkert, Andreas

    2012-10-01

    Hydrodynamic stability has been a longstanding issue for the cloud model of the broad line region in active galactic nuclei. We argue that the clouds may be gravitationally bound to the supermassive black hole. If true, stabilization by thermal pressure alone becomes even more difficult. We further argue that if magnetic fields are present in such clouds at a level that could affect the stability properties, they need to be strong enough to compete with the radiation pressure on the cloud. This would imply magnetic field values of a few gauss for a sample of active galactic nuclei we draw from the literature. We then investigate the effect of several magnetic configurations on cloud stability in axisymmetric magnetohydrodynamic simulations. For a purely azimuthal magnetic field which provides the dominant pressure support, the cloud first gets compressed by the opposing radiative and gravitational forces. The pressure inside the cloud then increases, and it expands vertically. Kelvin-Helmholtz and column density instabilities lead to a filamentary fragmentation of the cloud. This radiative dispersion continues until the cloud is shredded down to the resolution level. For a helical magnetic field configuration, a much more stable cloud core survives with a stationary density histogram which takes the form of a power law. Our simulated clouds develop sub-Alfvénic internal motions on the level of a few hundred km s-1.

  10. The Equations of Oceanic Motions

    NASA Astrophysics Data System (ADS)

    Müller, Peter

    2006-10-01

    Modeling and prediction of oceanographic phenomena and climate is based on the integration of dynamic equations. The Equations of Oceanic Motions derives and systematically classifies the most common dynamic equations used in physical oceanography, from large scale thermohaline circulations to those governing small scale motions and turbulence. After establishing the basic dynamical equations that describe all oceanic motions, M|ller then derives approximate equations, emphasizing the assumptions made and physical processes eliminated. He distinguishes between geometric, thermodynamic and dynamic approximations and between the acoustic, gravity, vortical and temperature-salinity modes of motion. Basic concepts and formulae of equilibrium thermodynamics, vector and tensor calculus, curvilinear coordinate systems, and the kinematics of fluid motion and wave propagation are covered in appendices. Providing the basic theoretical background for graduate students and researchers of physical oceanography and climate science, this book will serve as both a comprehensive text and an essential reference.

  11. Project Physics Tests 1, Concepts of Motion.

    ERIC Educational Resources Information Center

    Harvard Univ., Cambridge, MA. Harvard Project Physics.

    Test items relating to Project Physics Unit 1 are presented in this booklet, consisting of 70 multiple-choice and 20 problem-and-essay questions. Concepts of motion are examined with respect to velocities, acceleration, forces, vectors, Newton's laws, and circular motion. Suggestions are made for time consumption in answering some items. Besides…

  12. CLOUD CONDENSATION NUCLEI MEASUREMENTS WITHIN CLOUDS

    EPA Science Inventory

    Measurements of the spectra of cloud condensation nuclei (CCN) within and near the boundaries of clouds are presented. Some of the in-cloud measurements excluded the nuclei within cloud droplets (interstitial CCN) while others included all nuclei inside the cloud (total CCN). The...

  13. Potential of Higher Moments of the Radar Doppler Spectrum for Studying Ice Clouds

    NASA Astrophysics Data System (ADS)

    Loehnert, U.; Maahn, M.

    2015-12-01

    More observations of ice clouds are required to fill gaps in understanding of microphysical properties and processes. However, in situ observations by aircraft are costly and cannot provide long term observations which are required for a deeper understanding of the processes. Ground based remote sensing observations have the potential to fill this gap, but their observations do not contain sufficient information to unambiguously constrain ice cloud properties which leads to high uncertainties. For vertically pointing cloud radars, usually only reflectivity and mean Doppler velocity are used for retrievals; some studies proposed also the use of Doppler spectrum width.In this study, it is investigated whether additional information can be obtained by exploiting also higher moments of the Doppler spectrum such as skewness and kurtosis together with the slope of the Doppler peak. For this, observations of pure ice clouds from the Indirect and Semi-Direct Aerosol Campaign (ISDAC) in Alaska 2008 are analyzed. Using the ISDAC data set, an Optimal Estimation based retrieval is set up based on synthetic and real radar observations. The passive and active microwave radiative transfer model (PAMTRA) is used as a forward model together with the Self-Similar Rayleigh-Gans approximation for estimation of the scattering properties. The state vector of the retrieval consists of the parameters required to simulate the radar Doppler spectrum and describes particle mass, cross section area, particle size distribution, and kinematic conditions such as turbulence and vertical air motion. Using the retrieval, the information content (degrees of freedom for signal) is quantified that higher moments and slopes can contribute to an ice cloud retrieval. The impact of multiple frequencies, radar sensitivity and radar calibration is studied. For example, it is found that a single-frequency measurement using all moments and slopes contains already more information content than a dual

  14. Potential of Higher Moments of the Radar Doppler Spectrum for Studying Ice Clouds

    NASA Astrophysics Data System (ADS)

    Lunt, M. F.; Rigby, M. L.; Ganesan, A.; Manning, A.; O'Doherty, S.; Prinn, R. G.; Saito, T.; Harth, C. M.; Muhle, J.; Weiss, R. F.; Salameh, P.; Arnold, T.; Yokouchi, Y.; Krummel, P. B.; Steele, P.; Fraser, P. J.; Li, S.; Park, S.; Kim, J.; Reimann, S.; Vollmer, M. K.; Lunder, C. R.; Hermansen, O.; Schmidbauer, N.; Young, D.; Simmonds, P. G.

    2014-12-01

    More observations of ice clouds are required to fill gaps in understanding of microphysical properties and processes. However, in situ observations by aircraft are costly and cannot provide long term observations which are required for a deeper understanding of the processes. Ground based remote sensing observations have the potential to fill this gap, but their observations do not contain sufficient information to unambiguously constrain ice cloud properties which leads to high uncertainties. For vertically pointing cloud radars, usually only reflectivity and mean Doppler velocity are used for retrievals; some studies proposed also the use of Doppler spectrum width.In this study, it is investigated whether additional information can be obtained by exploiting also higher moments of the Doppler spectrum such as skewness and kurtosis together with the slope of the Doppler peak. For this, observations of pure ice clouds from the Indirect and Semi-Direct Aerosol Campaign (ISDAC) in Alaska 2008 are analyzed. Using the ISDAC data set, an Optimal Estimation based retrieval is set up based on synthetic and real radar observations. The passive and active microwave radiative transfer model (PAMTRA) is used as a forward model together with the Self-Similar Rayleigh-Gans approximation for estimation of the scattering properties. The state vector of the retrieval consists of the parameters required to simulate the radar Doppler spectrum and describes particle mass, cross section area, particle size distribution, and kinematic conditions such as turbulence and vertical air motion. Using the retrieval, the information content (degrees of freedom for signal) is quantified that higher moments and slopes can contribute to an ice cloud retrieval. The impact of multiple frequencies, radar sensitivity and radar calibration is studied. For example, it is found that a single-frequency measurement using all moments and slopes contains already more information content than a dual

  15. Plasma cloud behavior

    NASA Astrophysics Data System (ADS)

    Linson, Lewis M.

    1991-08-01

    Participation in PLACES (Position Location And Communications Effects Simulations) and Midnight Sky field operations is described. In the former, four barium releases were made during the period 4 to 12 December 1980. The range of velocities experienced was greater than before at this location. The principal challenge was to perform real-time tracking of the ion cloud so as to predict a future aim point for use in targeting beacon and probe rockets. Recommendations for obtaining smoother tracking data involve determining the motion of a field line through the ion cloud rather than an indeterminate point in the cloud, making measurements at set intervals, and coordinating measurements by more than one observer. During Midnight Sky, 2 barium releases were made on 29 March 81 and 2 April 81. The first went westerly at 450 m/s while the second was nearly motionless. A small aircraft was positioned so as to take photographs up the magnetic field line during the second release. It is strongly urged that a complete dry run including all participants, communications links, and necessary operations be carried out before a test event.

  16. A comparative assessment of Kalpana-1 and MISR cloud tracked winds over the Indian Ocean region

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    In this study, an attempt has been made to advance the error characteristic of atmospheric motion vectors (AMVs) derived from the infrared and water vapour channels of Kalpana-1 very high resolution radiometer by comparing against stereo motion vectors (SMVs) retrieved by tracking clouds from the multi-angle imaging spectro-radiometer (MISR) for a period of 9 months. Two different versions of the MISR SMVs with horizontal resolutions 70.4 and 17.6 km, respectively, are used for the inter-comparison. It is found that the Kalpana-1 AMV has stronger westerlies and southerlies than the MISR SMV at all latitudes and levels in majority of times. The performances of Kalpana-1 AMVs against MISR SMVs are assessed by doing a similar analysis where Meteosat-7 AMVs (infrared and water vapour AMVs) are also evaluated against the MISR SMVs for the same region. It is found that results of both AMVs (Kalpana-1 and Meteosat-7) with both sets of MISR SMVs are comparable with few exceptions. The zonal wind components of the MISR SMVs showed smaller mean wind difference and root mean square difference (RMSD) compared to the meridional wind components. The SMVs are typically assigned to higher altitudes than AMVs. Analysis related to the height discrepancies between MISR SMVs and AMVs shows that in the multi-layer cloud AMVs are tracked in upper level cloud targets, while SMVs are skewed more towards lower level. The accuracy is better for the low level where collocations are highly dense and gradually decreases towards the higher levels. Because of improvement in the MISR SMV retrieval algorithm, the errors in the meridional component of SMVs have improved in the recently released version with horizontal resolution of 17.6 km.

  17. CLOUD CHEMISTRY.

    SciTech Connect

    SCHWARTZ,S.E.

    2001-03-01

    Clouds present substantial concentrations of liquid-phase water, which can potentially serve as a medium for dissolution and reaction of atmospheric gases. The important precursors of acid deposition, SO{sub 2} and nitrogen oxides NO and NO{sub 2} are only sparingly soluble in clouds without further oxidation to sulfuric and nitric acids. In the case of SO{sub 2} aqueous-phase reaction with hydrogen peroxide, and to lesser extent ozone, are identified as important processes leading to this oxidation, and methods have been described by which to evaluate the rates of these reactions. The limited solubility of the nitrogen oxides precludes significant aqueous-phase reaction of these species, but gas-phase reactions in clouds can be important especially at night.

  18. Neptune's clouds

    NASA Technical Reports Server (NTRS)

    1999-01-01

    The bright cirrus-like clouds of Neptune change rapidly, often forming and dissipating over periods of several to tens of hours. In this sequence Voyager 2 observed cloud evolution in the region around the Great Dark Spot (GDS). The surprisingly rapid changes which occur separating each panel shows that in this region Neptune's weather is perhaps as dynamic and variable as that of the Earth. However, the scale is immense by our standards -- the Earth and the GDS are of similar size -- and in Neptune's frigid atmosphere, where temperatures are as low as 55 degrees Kelvin (-360 F), the cirrus clouds are composed of frozen methane rather than Earth's crystals of water ice. The Voyager Mission is conducted by JPL for NASA's Office of Space Science and Applications

  19. Lidar cloud studies for FIRE and ECLIPS

    NASA Technical Reports Server (NTRS)

    Sassen, Kenneth; Grund, Christian J.; Spinhirne, James D.; Hardesty, Michael; Alvarez, James

    1990-01-01

    Optical remote sensing measurements of cirrus cloud properties were collected by one airborne and four ground-based lidar systems over a 32 h period during this case study from the First ISCCP (International Satellite Cloud Climatology Program) Regional Experiment (FIRE) Intensive Field Observation (IFO) program. The lidar systems were variously equipped to collect linear depolarization, intrinsically calibrated backscatter, and Doppler velocity information. Data presented describe the temporal evolution and spatial distribution of cirrus clouds over an area encompassing southern and central Wisconsin. The cirrus cloud types include: dissipating subvisual and thin fibrous cirrus cloud bands, an isolated mesoscale uncinus complex (MUC), a large-scale deep cloud that developed into an organized cirrus structure within the lidar array, and a series of intensifying mesoscale cirrus cloud masses. Although the cirrus frequently developed in the vertical from particle fall-streaks emanating from generating regions at or near cloud tops, glaciating supercooled (-30 to -35 C) altocumulus clouds contributed to the production of ice mass at the base of the deep cirrus cloud, apparently even through riming, and other mechanisms involving evaporation, wave motions, and radiative effects are indicated. The generating regions ranged in scale from approximately 1.0 km cirrus uncinus cells, to organized MUC structures up to approximately 120 km across.

  20. Entrainment instability and vertical motion as causes of stratocumulus breakup

    NASA Technical Reports Server (NTRS)

    Weaver, C. J.; Pearson, R., Jr.

    1990-01-01

    Entrainment instability is thought to be a cause of stratocumulus breakup. At the interface between the cloud and the overlying air, mixtures may form which are negatively buoyant because of cloud droplet evaporation. Quantities devised to predict breakup are obtained from aircraft observations and are tested against cloud observations from satellite. Often, the parameters indicate that breakup should occur but the clouds remain, sometimes for several days. One possible explanation for breakup is vertical motion from passing synoptic cyclones. Several cases suggest that breakup is associated with the downward vertical motion from the cold air advected behind an eastward moving cyclone.

  1. Interaction of a neutral cloud moving through a magnetized plasma

    NASA Technical Reports Server (NTRS)

    Goertz, C. K.; Lu, G.

    1990-01-01

    Current collection by outgassing probes in motion relative to a magnetized plasma may be significantly affected by plasma processes that cause electron heating and cross field transport. Simulations of a neutral gas cloud moving across a static magnetic field are discussed. The authors treat a low-Beta plasma and use a 2-1/2 D electrostatic code linked with the authors' Plasma and Neutral Interaction Code (PANIC). This study emphasizes the understanding of the interface between the neutral gas cloud and the surrounding plasma where electrons are heated and can diffuse across field lines. When ionization or charge exchange collisions occur a sheath-like structure is formed at the surface of the neutral gas. In that region the crossfield component of the electric field causes the electron to E times B drift with a velocity of the order of the neutral gas velocity times the square root of the ion to electron mass ratio. In addition a diamagnetic drift of the electron occurs due to the number density and temperature inhomogeneity in the front. These drift currents excite the lower-hybrid waves with the wave k-vectors almost perpendicular to the neutral flow and magnetic field again resulting in electron heating. The thermal electron current is significantly enhanced due to this heating.

  2. Our World: Cool Clouds

    NASA Video Gallery

    Learn how clouds are formed and watch an experiment to make a cloud using liquid nitrogen. Find out how scientists classify clouds according to their altitude and how clouds reflect and absorb ligh...

  3. The relationship between mesoscale circulation and cloud morphology at the upper cloud level of Venus from VMC/Venus Express

    NASA Astrophysics Data System (ADS)

    Patsaeva, M. V.; Khatuntsev, I. V.; Patsaev, D. V.; Titov, D. V.; Ignatiev, N. I.; Markiewicz, W. J.; Rodin, A. V.

    2015-08-01

    The Venus Monitoring Camera (VMC) acquired a set of ultraviolet (UV) images during the Venus Express mission unprecedented in its duration from May 2006 to September 2013. Here we present the results of digital tracking of the cloud features in the upper cloud layer at latitudes 25-75°S using images from 257 orbits with the best spatial coverage. The method relies on analysis of correlations between pairs of UV images separated in time. The bulk of data processed allows us to clarify the reasons why the mid-latitude jet is not always present in latitudinal wind profiles. Comparing VMC images with wind velocity fields we found a relationship between cloud morphology at middle latitudes and the circulation. The vector field in middle latitudes depends on the presence of a contrast global streak in the cloud morphology tilted with respect to latitude circles. The angle of the flow deflection (the angle between the wind velocity and latitudinal circles) and the difference of the zonal velocity on the opposite sides of the streak are in direct relationship to the angle between the streak and latitude circles. During such orbits the jet bulge does not appear in the latitudinal profile of the zonal wind component. Otherwise a zonal flow with small changes of the meridional velocity dominates in middle latitudes and manifests itself as a jet bulge. The relationship between the cloud cover morphology and circulation peculiarities can be attributed to the motion of global cloud features, like the Y-feature. We prepared plots of zonal and meridional velocities averaged with respect to the entire observation period. The average zonal velocity has a diurnal maximum at 15:00 local solar time and at 40°S. The meridional velocity reaches its maximum between 13:00 and 16:00 and at 50°S. The velocities obtained by the digital method are in good agreement with results of the visual method in the middle latitudes published earlier by Khatuntsev et al. (2013).

  4. Cloud classification using whole-sky imager data

    SciTech Connect

    Buch, K.A. Jr.; Sun, C.H.; Thorne, L.R.

    1996-04-01

    Clouds are one of the most important moderators of the earth radiation budget and one of the least understood. The effect that clouds have on the reflection and absorption of solar and terrestrial radiation is strongly influenced by their shape, size, and composition. Physically accurate parameterization of clouds is necessary for any general circulation model (GCM) to yield meaningful results. The work presented here is part of a larger project that is aimed at producing realistic three-dimensional (3D) volume renderings of cloud scenes based on measured data from real cloud scenes. These renderings will provide the important shape information for parameterizing GCMs. The specific goal of the current study is to develop an algorithm that automatically classifies (by cloud type) the clouds observed in the scene. This information will assist the volume rendering program in determining the shape of the cloud. Much work has been done on cloud classification using multispectral satellite images. Most of these references use some kind of texture measure to distinguish the different cloud types and some also use topological features (such as cloud/sky connectivity or total number of clouds). A wide variety of classification methods has been used, including neural networks, various types of clustering, and thresholding. The work presented here uses binary decision trees to distinguish the different cloud types based on cloud features vectors.

  5. A generalized nonlocal vector calculus

    NASA Astrophysics Data System (ADS)

    Alali, Bacim; Liu, Kuo; Gunzburger, Max

    2015-10-01

    A nonlocal vector calculus was introduced in Du et al. (Math Model Meth Appl Sci 23:493-540, 2013) that has proved useful for the analysis of the peridynamics model of nonlocal mechanics and nonlocal diffusion models. A formulation is developed that provides a more general setting for the nonlocal vector calculus that is independent of particular nonlocal models. It is shown that general nonlocal calculus operators are integral operators with specific integral kernels. General nonlocal calculus properties are developed, including nonlocal integration by parts formula and Green's identities. The nonlocal vector calculus introduced in Du et al. (Math Model Meth Appl Sci 23:493-540, 2013) is shown to be recoverable from the general formulation as a special example. This special nonlocal vector calculus is used to reformulate the peridynamics equation of motion in terms of the nonlocal gradient operator and its adjoint. A new example of nonlocal vector calculus operators is introduced, which shows the potential use of the general formulation for general nonlocal models.

  6. Complex Clouds

    Atmospheric Science Data Center

    2013-04-16

    ...     View Larger Image The complex structure and beauty of polar clouds are highlighted by these images acquired ... Multi-angle Imaging SpectroRadiometer observes the daylit Earth continuously from pole to pole, and every 9 days views the entire globe ...

  7. Thin Clouds

    Atmospheric Science Data Center

    2013-04-18

    ... of this montage is a natural-color view of the Caribbean Sea east of the Yucatan Peninsula as seen by MISR's most steeply ... - Thin, feathery clouds of ice crystals over the Caribbean Sea. project:  MISR category:  gallery ...

  8. Circular motion

    NASA Astrophysics Data System (ADS)

    Newton, Isaac; Henry, Richard Conn

    2000-07-01

    An extraordinarily simple and transparent derivation of the formula for the acceleration that occurs in uniform circular motion is presented, and is advocated for use in high school and college freshman physics textbooks.

  9. Cloud Thickness from Diffusion of Lidar Pulses in Clouds

    NASA Technical Reports Server (NTRS)

    Cahalan, Robert F.; Davis, A.; McGill, Matthew

    1999-01-01

    Measurements of the distribution of reflected light from a laser beam incident on an aqueous suspension of particles or "cloud" with known thickness and particle size distribution are reported. The distribution is referred to as the "cloud radiative Green's function", G. In the diffusion domain, G is sensitive to cloud thickness, allowing that important quantity to be retrieved. The goal of the laboratory simulation is to provide preliminary estimates of sensitivity of G to cloud thickness,for use in the optimal design of an offbeam Lidar instrument for remote sensing of cloud thickness (THOR, Thickness from Offbeam Returns). These clouds of polystyrene microspheres suspended in water are analogous to real clouds of water droplets suspended in air. The microsphere size distribution is roughly lognormal, from 0.5 microns to 25 microns, similar to real clouds. Density of suspended spheres is adjusted so mean-free-path of visible photons is about 10 cm, approximately 1000 times smaller than in real clouds. The light source is a ND:YAG laser at 530 nm. Detectors are flux and photon-counting Photomultiplier Tube (PMTS), with a glass probe for precise positioning. A Labview 5 VI controls positioning, and data acquisition, via an NI Motion Control board connected to a stepper motor driving an Edmund linear slider, and a 16-channel 16-bit NI-DAQ board. The stepper motor is accurate to 10 microns, and step size is selectable from the VI software. Far from the incident beam, the rate of exponential increase as the direction of the incident beam is approached scales as expected from diffusion theory, linearly with the cloud thickness, and inversely as the square root of the reduced optical thickness, and is independent of particle size. Near the beam the signal begins to increase faster than exponential, due to single and low-order scattering near the backward direction, and here the distribution depends on particle size. Results are being used to verify 3D Monte Carlo

  10. The mean-square error optimal linear discriminant function and its application to incomplete data vectors

    NASA Technical Reports Server (NTRS)

    Walker, H. F.

    1979-01-01

    In many pattern recognition problems, data vectors are classified although one or more of the data vector elements are missing. This problem occurs in remote sensing when the ground is obscured by clouds. Optimal linear discrimination procedures for classifying imcomplete data vectors are discussed.

  11. Polar motion

    NASA Technical Reports Server (NTRS)

    Kolenkiewicz, R.

    1973-01-01

    Tracking of the Beacon Explorer-C satellite by a precision laser system was used to measure the polar motion and solid earth tide. The tidal perturbation of satellite latitude is plotted as variation in maximum latitude in seconds of arc on earth's surface as a function of the date, and polar motion is shown by plotting the variation in latitude of the laser in seconds of arc along the earth's surface as a function of date

  12. Development of a radiative cloud parameterization scheme of stratocumulus and stratus clouds which includes the impact of CCN on cloud albedo

    SciTech Connect

    Cotton, W.R.

    1994-01-18

    The objective of this research is to develop a parameterization scheme that is able to dispose or predict changes in stratocumulus cloud cover, atmospheric boundary layer (ABL) stability, liquid water paths (LWPs), and cloud albedo due to changes in sea-surface temperatures, large scale vertical motion and wind shear, and cloud condensation nuclei (CCN). The motivation for developing such a parameterization scheme is that it is hypothesized that anthropogenic sources of CCN can result in increased concentrations of cloud droplets. The higher concentrations of CCN result in higher concentrations of cloud droplets, thereby enhancing cloud albedo which in the absence of other effects will induce a climate forcing opposed to that associated with ``Greenhouse`` warming. As a result of the complicated interactions between cloud microstructure, cloud macrostructure, and cloud radiative transfer, only a limited range of clouds are susceptible to changes in CCN concentrations causing changes in cloud albedo. It is the intent of this research to determine the range of cloud types that are susceptible to albedo changes by anthropogenic CCN and incorporate that information into a cloud parameterization scheme.

  13. EDITORIAL: Focus on Cloud Physics FOCUS ON CLOUD PHYSICS

    NASA Astrophysics Data System (ADS)

    Falkovich, Gregory; Malinowski, Szymon P.

    2008-07-01

    Cloud physics has for a long time been an important segment of atmospheric science. It is common knowledge that clouds are crucial for our understanding of weather and climate. Clouds are also interesting by themselves (not to mention that they are beautiful). Complexity is hidden behind the common picture of these beautiful and interesting objects. The typical school textbook definition that a cloud is 'a set of droplets or particles suspended in the atmosphere' is not adequate. Clouds are complicated phenomena in which dynamics, turbulence, microphysics, thermodynamics and radiative transfer interact on a wide range of scales, from sub-micron to kilometres. Some of these interactions are subtle and others are more straightforward. Large and small-scale motions lead to activation of cloud condensation nuclei, condensational growth and collisions; small changes in composition and concentration of atmospheric aerosol lead to significant differences in radiative properties of the clouds and influence rainfall formation. It is justified to look at a cloud as a composite, nonlinear system which involves many interactions and feedback. This system is actively linked into a web of atmospheric, oceanic and even cosmic interactions. Due to the complexity of the cloud system, present-day descriptions of clouds suffer from simplifications, inadequate parameterizations, and omissions. Sometimes the most fundamental physics hidden behind these simplifications and parameterizations is not known, and a wide scope of view can sometimes prevent a 'microscopic', deep insight into the detail. Only the expertise offered by scientists focused on particular elementary processes involved in this complicated pattern of interactions allows us to shape elements of the puzzle from which a general picture of clouds can be created. To be useful, every element of the puzzle must be shaped precisely. This often creates problems in communication between the sciences responsible for shaping

  14. A Flexible Turbulent Vector Field Generator

    NASA Astrophysics Data System (ADS)

    Benassi, A.; Davis, A.

    2004-12-01

    Analysis and generation of turbulent vector fields is a necessity in many areas, such as Atmospheric Science. A candidate model of vector field must be flexible enough to tune some features, such as the spacial distribution of vortices, sinks and sources, according to physical measures. To achieve that goal, we propose a model that depends upon a given matricial function called "topolet" and a law of random vectors family. This model has a hierarchical structure. Its spinal column is a tree: the encoding tree of the domain where the vector field lives. The sets of vortices, sinks and sources are driven by some Bernouilli subtrees, directly giving their fractal dimension. At each node of the tree is attached a rate of energy loose giving the spectral slope. All those quantities are independantly identifiable on the base of mathematical proofs. A primitive version of this model have been proposed for generating clouds.

  15. Interstellar Gas Flow Vector and Temperature Determination over 5 Years of IBEX Observations

    NASA Astrophysics Data System (ADS)

    Möbius, E.; Bzowski, M.; Fuselier, S. A.; Heirtzler, D.; Kubiak, M. A.; Kucharek, H.; Lee, M. A.; Leonard, T.; McComas, D. J.; Schwadron, N.; Sokół, J. M.; Wurz, P.

    2015-01-01

    The Interstellar Boundary Explorer (IBEX) observes the interstellar neutral gas flow trajectories at their perihelion in Earth's orbit every year from December through early April, when the Earth's orbital motion is into the oncoming flow. These observations have defined a narrow region of possible, but very tightly coupled interstellar neutral flow parameters, with inflow speed, latitude, and temperature as well-defined functions of inflow longitude. The best- fit flow vector is different by ≈ 3° and lower by ≈ 3 km/s than obtained previously with Ulysses GAS, but the temperature is comparable. The possible coupled parameter space reaches to the previous flow vector, but only for a substantially higher temperature (by ≈ 2000 K). Along with recent pickup ion observations and including historical observations of the interstellar gas, these findings have led to a discussion, whether the interstellar gas flow into the solar system has been stable or variable over time. These intriguing possibilities call for more detailed analysis and a longer database. IBEX has accumulated observations over six interstellar flow seasons. We review key observations and refinements in the analysis, in particular, towards narrowing the uncertainties in the temperature determination. We also address ongoing attempts to optimize the flow vector determination through varying the IBEX spacecraft pointing and discuss related implications for the local interstellar cloud and its interaction with the heliosphere.

  16. Image transfer through cirrus clouds. II. Wave-front segmentation and imaging.

    PubMed

    Landesman, Barbara T; Matson, Charles L

    2002-12-20

    A hybrid technique to simulate the imaging of space-based objects through cirrus clouds is presented. The method makes use of standard Huygens-Fresnel propagation beyond the cloud boundary and a novel vector trace approach within the cloud. At the top of the cloud, the wave front is divided into an array of input gradient vectors, which are in turn transmitted through the cloud model by use of the Coherent Illumination Ray Trace and Imaging Software for Cirrus. At the bottom of the cloud, the output vector distribution is used to reconstruct a wave front that continues propagating to the ground receiver. Images of the object as seen through cirrus clouds with different optical depths are compared with a diffraction-limited image. Turbulence effects from the atmospheric propagation are not included. PMID:12510928

  17. Stellar Encounters with the Oort Cloud Based on Hipparcos Data

    NASA Technical Reports Server (NTRS)

    Garcia-Sanchez, J.; Preston, R. A.; Jones, D. L.; Weissman, P. R.; Lestrade, J. F.; Latham, D. W.; Stefanik, R. P.

    1998-01-01

    We have combined Hipparcos proper motion and parallax data for nearby stars with ground-based radial velocity measurements to find stars which may have passed (or will pass) close enough to the Sun to perturb the Oort cloud.

  18. A global survey of cloud overlap based on CALIPSO and CloudSat measurements

    NASA Astrophysics Data System (ADS)

    Li, J.; Huang, J.; Stamnes, K.; Wang, T.; Lv, Q.; Jin, H.

    2015-01-01

    actual cloud fractions for multilayered cloud types (e.g., As + St/Sc and Ac + St/Sc) over the Southern Ocean. The establishment of a statistical relationship between multilayered cloud types and the environmental conditions (e.g., atmospheric vertical motion, convective stability and wind shear) would be useful for parameterization design of cloud overlap in numerical models.

  19. Topographic Structure from Motion

    NASA Astrophysics Data System (ADS)

    Fonstad, M. A.; Dietrich, J. T.; Courville, B. C.; Jensen, J.; Carbonneau, P.

    2011-12-01

    The production of high-resolution topographic datasets is of increasing concern and application throughout the geomorphic sciences, and river science is no exception. Consequently, a wide range of topographic measurement methods have evolved. Despite the range of available methods, the production of high resolution, high quality digital elevation models (DEMs) generally requires a significant investment in personnel time, hardware and/or software. However, image-based methods such as digital photogrammetry have steadily been decreasing in costs. Initially developed for the purpose of rapid, inexpensive and easy three dimensional surveys of buildings or small objects, the "structure from motion" photogrammetric approach (SfM) is a purely image based method which could deliver a step-change if transferred to river remote sensing, and requires very little training and is extremely inexpensive. Using the online SfM program Microsoft Photosynth, we have created high-resolution digital elevation models (DEM) of rivers from ordinary photographs produced from a multi-step workflow that takes advantage of free and open source software. This process reconstructs real world scenes from SfM algorithms based on the derived positions of the photographs in three-dimensional space. One of the products of the SfM process is a three-dimensional point cloud of features present in the input photographs. This point cloud can be georeferenced from a small number of ground control points collected via GPS in the field. The georeferenced point cloud can then be used to create a variety of digital elevation model products. Among several study sites, we examine the applicability of SfM in the Pedernales River in Texas (USA), where several hundred images taken from a hand-held helikite are used to produce DEMs of the fluvial topographic environment. This test shows that SfM and low-altitude platforms can produce point clouds with point densities considerably better than airborne LiDAR, with

  20. Hidden symmetry of hyperbolic monopole motion

    NASA Astrophysics Data System (ADS)

    Gibbons, G. W.; Warnick, C. M.

    2007-10-01

    Hyperbolic monopole motion is studied for well separated monopoles. It is shown that the motion of a hyperbolic monopole in the presence of one or more fixed monopoles is equivalent to geodesic motion on a particular submanifold of the full moduli space. The metric on this submanifold is found to be a generalisation of the multi-centre Taub-NUT metric introduced by LeBrun. The one centre case is analysed in detail as a special case of a class of systems admitting a conserved Runge-Lenz vector. The two centre problem is also considered. An integrable classical string motion is exhibited.

  1. Are Bred Vectors The Same As Lyapunov Vectors?

    NASA Astrophysics Data System (ADS)

    Kalnay, E.; Corazza, M.; Cai, M.

    Regional loss of predictability is an indication of the instability of the underlying flow, where small errors in the initial conditions (or imperfections in the model) grow to large amplitudes in finite times. The stability properties of evolving flows have been studied using Lyapunov vectors (e.g., Alligood et al, 1996, Ott, 1993, Kalnay, 2002), singular vectors (e.g., Lorenz, 1965, Farrell, 1988, Molteni and Palmer, 1993), and, more recently, with bred vectors (e.g., Szunyogh et al, 1997, Cai et al, 2001). Bred vectors (BVs) are, by construction, closely related to Lyapunov vectors (LVs). In fact, after an infinitely long breeding time, and with the use of infinitesimal ampli- tudes, bred vectors are identical to leading Lyapunov vectors. In practical applications, however, bred vectors are different from Lyapunov vectors in two important ways: a) bred vectors are never globally orthogonalized and are intrinsically local in space and time, and b) they are finite-amplitude, finite-time vectors. These two differences are very significant in a dynamical system whose size is very large. For example, the at- mosphere is large enough to have "room" for several synoptic scale instabilities (e.g., storms) to develop independently in different regions (say, North America and Aus- tralia), and it is complex enough to have several different possible types of instabilities (such as barotropic, baroclinic, convective, and even Brownian motion). Bred vectors share some of their properties with leading LVs (Corazza et al, 2001a, 2001b, Toth and Kalnay, 1993, 1997, Cai et al, 2001). For example, 1) Bred vectors are independent of the norm used to define the size of the perturba- tion. Corazza et al. (2001) showed that bred vectors obtained using a potential enstro- phy norm were indistinguishable from bred vectors obtained using a streamfunction squared norm, in contrast with singular vectors. 2) Bred vectors are independent of the length of the rescaling period as long as the

  2. Clouds and Dust Storms

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Released 2 July 2004 The atmosphere of Mars is a dynamic system. Water-ice clouds, fog, and hazes can make imaging the surface from space difficult. Dust storms can grow from local disturbances to global sizes, through which imaging is impossible. Seasonal temperature changes are the usual drivers in cloud and dust storm development and growth.

    Eons of atmospheric dust storm activity has left its mark on the surface of Mars. Dust carried aloft by the wind has settled out on every available surface; sand dunes have been created and moved by centuries of wind; and the effect of continual sand-blasting has modified many regions of Mars, creating yardangs and other unusual surface forms.

    This image was acquired during mid-spring near the North Pole. The linear water-ice clouds are now regional in extent and often interact with neighboring cloud system, as seen in this image. The bottom of the image shows how the interaction can destroy the linear nature. While the surface is still visible through most of the clouds, there is evidence that dust is also starting to enter the atmosphere.

    Image information: VIS instrument. Latitude 68.4, Longitude 180 East (180 West). 38 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with

  3. Torus-Shaped Dust Clouds in Magnetized Anodic Plasmas

    SciTech Connect

    Pilch, I.; Reichstein, T.; Greiner, F.; Piel, A.

    2008-09-07

    The generation of a torus-shaped dust cloud in an anodic plasma is decribed. The confined dust particles perfom a rotational motion around the torus major axis. The structure of the cloud in dependence of the external parameters are observed and the rotation velocity of the particles was measured and compared with a simple estimate.

  4. Asteroid Motions

    NASA Astrophysics Data System (ADS)

    Sykes, Mary V.; Moynihan, P. Daniel

    1996-12-01

    Equations are derived which describe the apparent motion of an asteroid traveling on an elliptical orbit in geocentric ecliptic coordinates. At opposition, the equations are identical to those derived by Bowellet al. (Bowell, E., B. Skiff, and L. Wasserman 1990. InAsteroids, Comets, Meteors III(C.-I. Lagerkvist, M. Rickman, B. A. Lindblad, and M. Lindgren, Eds.), pp. 19-24. Uppsala Universitet, Uppsala, Sweden). These equations can be an important component in the optimization of search strategies for specific asteroid populations based on their apparent motions relative to other populations when observed away from opposition.

  5. Present-day plate motions

    NASA Technical Reports Server (NTRS)

    Minster, J. B.; Jordan, T. H.

    1977-01-01

    A data set comprising 110 spreading rates, 78 transform fault azimuths and 142 earthquake slip vectors was inverted to yield a new instantaneous plate motion model, designated RM2. The mean averaging interval for the relative motion data was reduced to less than 3 My. A detailed comparison of RM2 with angular velocity vectors which best fit the data along individual plate boundaries indicates that RM2 performs close to optimally in most regions, with several notable exceptions. On the other hand, a previous estimate (RM1) failed to satisfy an extensive set of new data collected in the South Atlantic Ocean. It is shown that RM1 incorrectly predicts the plate kinematics in the South Atlantic because the presently available data are inconsistent with the plate geometry assumed in deriving RM1. It is demonstrated that this inconsistency can be remedied by postulating the existence of internal deformation with the Indian plate, although alternate explanations are possible.

  6. Seasonal variation and physical properties of the cloud system over southeastern China derived from CloudSat products

    NASA Astrophysics Data System (ADS)

    Guo, Zhun; Zhou, Tianjun

    2015-05-01

    Based on the National Centers for Environmental Prediction (NCEP) and Climate Prediction Center (CPC) Merged Analysis of Precipitation (CMAP) data and CloudSat products, the seasonal variations of the cloud properties, vertical occurrence frequency, and ice water content of clouds over southeastern China were investigated in this study. In the CloudSat data, a significant alternation in high or low cloud patterns was observed from winter to summer over southeastern China. It was found that the East Asian Summer Monsoon (EASM) circulation and its transport of moisture leads to a conditional instability, which benefits the local upward motion in summer, and thereby results in an increased amount of high cloud. The deep convective cloud centers were found to coincide well with the northward march of the EASM, while cirrus lagged slightly behind the convection center and coincided well with the outflow and meridional wind divergence of the EASM. Analysis of the radiative heating rates revealed that both the plentiful summer moisture and higher clouds are effective in destabilizing the atmosphere. Moreover, clouds heat the mid-troposphere and the cloud radiative heating is balanced by adiabatic cooling through upward motion, which causes meridional wind by the Sverdrup balance. The cloud heating-forced circulation was observed to coincide well with the EASM circulation, serving as a positive effect on EASM circulation.

  7. Vectors in Use in a 3D Juggling Game Simulation

    ERIC Educational Resources Information Center

    Kynigos, Chronis; Latsi, Maria

    2006-01-01

    The new representations enabled by the educational computer game the "Juggler" can place vectors in a central role both for controlling and measuring the behaviours of objects in a virtual environment simulating motion in three-dimensional spaces. The mathematical meanings constructed by 13 year-old students in relation to vectors as objects, as a…

  8. Estimating Cloud Cover

    ERIC Educational Resources Information Center

    Moseley, Christine

    2007-01-01

    The purpose of this activity was to help students understand the percentage of cloud cover and make more accurate cloud cover observations. Students estimated the percentage of cloud cover represented by simulated clouds and assigned a cloud cover classification to those simulations. (Contains 2 notes and 3 tables.)

  9. Instrument measures cloud cover

    NASA Technical Reports Server (NTRS)

    Laue, E. G.

    1981-01-01

    Eight solar sensing cells comprise inexpensive monitoring instrument. Four cells always track Sun while other four face sky and clouds. On overcast day, cloud-irradiance sensors generate as much short-circuit current as Sun sensor cells. As clouds disappear, output of cloud sensors decreases. Ratio of two sensor type outputs determines fractional cloud cover.

  10. Integrals of motion for the classical two-body problem with drag

    NASA Technical Reports Server (NTRS)

    Jezewski, D. J.; Mittleman, D.

    1983-01-01

    Integrals of motion for the two-body problem with drag are obtained by operating on the second-order vector differential equation describing the motion. The force field consists of an inverse-square gravitational attraction and a drag force proportional to the velocity vector and inversely proportional to the square of the distance to the attracting center. The developed integrals are the analogs of the Keplerian scalar energy, the vector angular momentum, and the Laplace vector.

  11. What's Motion Sickness?

    MedlinePlus

    ... Homework? Here's Help White House Lunch Recipes What's Motion Sickness? KidsHealth > For Kids > What's Motion Sickness? Print ... motion sickness might get even worse. continue Avoiding Motion Sickness To avoid motion sickness: Put your best ...

  12. Brownian Motion.

    ERIC Educational Resources Information Center

    Lavenda, Bernard H.

    1985-01-01

    Explains the phenomenon of Brownian motion, which serves as a mathematical model for random processes. Topics addressed include kinetic theory, Einstein's theory, particle displacement, and others. Points out that observations of the random course of a particle suspended in fluid led to the first accurate measurement of atomic mass. (DH)

  13. Point Cloud Server (pcs) : Point Clouds In-Base Management and Processing

    NASA Astrophysics Data System (ADS)

    Cura, R.; Perret, J.; Paparoditis, N.

    2015-08-01

    In addition to the traditional Geographic Information System (GIS) data such as images and vectors, point cloud data has become more available. It is appreciated for its precision and true three-Dimensional (3D) nature. However, managing the point cloud can be difficult due to scaling problems and specificities of this data type. Several methods exist but are usually fairly specialised and solve only one aspect of the management problem. In this work, we propose a complete and efficient point cloud management system based on a database server that works on groups of points rather than individual points. This system is specifically designed to solve all the needs of point cloud users: fast loading, compressed storage, powerful filtering, easy data access and exporting, and integrated processing. Moreover, the system fully integrates metadata (like sensor position) and can conjointly use point clouds with images, vectors, and other point clouds. The system also offers in-base processing for easy prototyping and parallel processing and can scale well. Lastly, the system is built on open source technologies; therefore it can be easily extended and customised. We test the system will several billion points of point clouds from Lidar (aerial and terrestrial ) and stereo-vision. We demonstrate ~ 400 million pts/h loading speed, user-transparent greater than 2 to 4:1 compression ratio, filtering in the approximately 50 ms range, and output of about a million pts/s, along with classical processing, such as object detection.

  14. Characterization of free breathing patterns with 5D lung motion model

    SciTech Connect

    Zhao Tianyu; Lu Wei; Yang Deshan; Mutic, Sasa; Noel, Camille E.; Parikh, Parag J.; Bradley, Jeffrey D.; Low, Daniel A.

    2009-11-15

    Purpose: To determine the quiet respiration breathing motion model parameters for lung cancer and nonlung cancer patients. Methods: 49 free breathing patient 4DCT image datasets (25 scans, cine mode) were collected with simultaneous quantitative spirometry. A cross-correlation registration technique was employed to track the lung tissue motion between scans. The registration results were applied to a lung motion model: X-vector=X-vector{sub 0}+{alpha}-vector{beta}-vector f, where X-vector is the position of a piece of tissue located at reference position X-vector{sub 0} during a reference breathing phase (zero tidal volume v, zero airflow f). {alpha}-vector is a parameter that characterizes the motion due to air filling (motion as a function of tidal volume v) and {beta}-vector is the parameter that accounts for the motion due to the imbalance of dynamical stress distributions during inspiration and exhalation that causes lung motion hysteresis (motion as a function of airflow f). The parameters {alpha}-vector and {beta}-vector together provide a quantitative characterization of breathing motion that inherently includes the complex hysteresis interplay. The {alpha}-vector and {beta}-vector distributions were examined for each patient to determine overall general patterns and interpatient pattern variations. Results: For 44 patients, the greatest values of |{alpha}-vector| were observed in the inferior and posterior lungs. For the rest of the patients, |{alpha}-vector| reached its maximum in the anterior lung in three patients and the lateral lung in two patients. The hysteresis motion {beta}-vector had greater variability, but for the majority of patients, |{beta}-vector| was largest in the lateral lungs. Conclusions: This is the first report of the three-dimensional breathing motion model parameters for a large cohort of patients. The model has the potential for noninvasively predicting lung motion. The majority of patients exhibited similar |{alpha}-vector| maps

  15. Rotations with Rodrigues' Vector

    ERIC Educational Resources Information Center

    Pina, E.

    2011-01-01

    The rotational dynamics was studied from the point of view of Rodrigues' vector. This vector is defined here by its connection with other forms of parametrization of the rotation matrix. The rotation matrix was expressed in terms of this vector. The angular velocity was computed using the components of Rodrigues' vector as coordinates. It appears…

  16. Bred vectors, singular vectors, and Lyapunov vectors in simple and complex models

    NASA Astrophysics Data System (ADS)

    Norwood, Adrienne

    We compute and compare three types of vectors frequently used to explore the instability properties of dynamical models, Lyapunov vectors (LVs), singular vectors (SVs), and bred vectors (BVs). The first model is the Lorenz (1963) three-variable model. We find BVs align with the locally fastest growing LV, which is often the second fastest growing global LV. The growth rates of the three types of vectors reveal all predict regime changes and durations of new regimes, as shown for BVs by Evans et al. (2004). The second model is the toy 'atmosphere-ocean model' developed by Pena and Kalnay (2004) coupling three Lorenz (1963) models with different time scales to test the effects of fast and slow modes of growth on the dynamical vectors. A fast 'extratropical atmosphere' is weakly coupled to a fast 'tropical atmosphere' which is strongly coupled to a slow 'ocean' system, the latter coupling imitating the tropical El Nino--Southern Oscillation. BVs separate the fast and slow modes of growth through appropriate selection of the breeding parameters. LVs successfully separate the fast 'extratropics' but cannot completely decouple the 'tropics' from the 'ocean,' leading to 'coupled' LVs that are affected by both systems but mainly dominated by one. SVs identify the fast modes but cannot capture the slow modes until the fast 'extratropics' are replaced with faster 'convection.' The dissimilar behavior of the three types of vectors degrades the similarities of the subspaces they inhabit (Norwood et al. 2013). The third model is a quasi-geostrophic channel model (Rotunno and Bao 1996) that is a simplification of extratropical synoptic-scale motions with baroclinic instabilities only. We were unable to successfully compute LVs for it. However, randomly initialized BVs quickly converge to a single vector that is the leading LV. The last model is the SPEEDY model created by Molteni (2003). It is a simplified general atmospheric circulation model with several types of instabilities

  17. The spin vector of Venus

    NASA Technical Reports Server (NTRS)

    Shapiro, I. I.; Chandler, J. F.; Campbell, D. B.; Hine, A. A.; Stacy, N. J. S.

    1990-01-01

    Analysis of radar observations from 1964 through 1983 yields the following values for the components of the spin vector of Venus: P = 243.026 + or - 0.006 d (retrograde); alpha = 272.75 + or - 0.09 deg; and delta = 67.10 + or - 0.09 deg, where the standard errors quoted are three- to five-fold larger than the statistical standard errors and encompass the changes in results obtained by various tests designed to expose possible systematic errors. These values demonstrate conclusively that the spin state of Venus is not in resonance with the relative orbital motions of Venus and earth.

  18. Foamy virus vectors.

    PubMed Central

    Russell, D W; Miller, A D

    1996-01-01

    Human foamy virus (HFV) is a retrovirus of the spumavirus family. We have constructed vectors based on HFV that encode neomycin phosphotransferase and alkaline phosphatase. These vectors are able to transduce a wide variety of vertebrate cells by integration of the vector genome. Unlike vectors based on murine leukemia virus, HFV vectors are not inactivated by human serum, and they transduce stationary-phase cultures more efficiently than murine leukemia virus vectors. These properties, as well as their large packaging capacity, make HFV vectors promising gene transfer vehicles. PMID:8523528

  19. Dry air entrainment into convective clouds

    NASA Technical Reports Server (NTRS)

    Telford, J. W.

    1977-01-01

    A systematic approach to the study of atmospheric turbulent motion is discussed in terms of weather modification. The background of cloud physics, and the mixing process are described. A zero-g study is proposed to enable the basic experimental data to be collected so that theory may be developed to generalize results for practical applications.

  20. Deblurring for spatial and temporal varying motion with optical computing

    NASA Astrophysics Data System (ADS)

    Xiao, Xiao; Xue, Dongfeng; Hui, Zhao

    2016-05-01

    A way to estimate and remove spatially and temporally varying motion blur is proposed, which is based on an optical computing system. The translation and rotation motion can be independently estimated from the joint transform correlator (JTC) system without iterative optimization. The inspiration comes from the fact that the JTC system is immune to rotation motion in a Cartesian coordinate system. The work scheme of the JTC system is designed to keep switching between the Cartesian coordinate system and polar coordinate system in different time intervals with the ping-pang handover. In the ping interval, the JTC system works in the Cartesian coordinate system to obtain a translation motion vector with optical computing speed. In the pang interval, the JTC system works in the polar coordinate system. The rotation motion is transformed to the translation motion through coordinate transformation. Then the rotation motion vector can also be obtained from JTC instantaneously. To deal with continuous spatially variant motion blur, submotion vectors based on the projective motion path blur model are proposed. The submotion vectors model is more effective and accurate at modeling spatially variant motion blur than conventional methods. The simulation and real experiment results demonstrate its overall effectiveness.

  1. Vector Acoustics, Vector Sensors, and 3D Underwater Imaging

    NASA Astrophysics Data System (ADS)

    Lindwall, D.

    2007-12-01

    Vector acoustic data has two more dimensions of information than pressure data and may allow for 3D underwater imaging with much less data than with hydrophone data. The vector acoustic sensors measures the particle motions due to passing sound waves and, in conjunction with a collocated hydrophone, the direction of travel of the sound waves. When using a controlled source with known source and sensor locations, the reflection points of the sound field can be determined with a simple trigonometric calculation. I demonstrate this concept with an experiment that used an accelerometer based vector acoustic sensor in a water tank with a short-pulse source and passive scattering targets. The sensor consists of a three-axis accelerometer and a matched hydrophone. The sound source was a standard transducer driven by a short 7 kHz pulse. The sensor was suspended in a fixed location and the hydrophone was moved about the tank by a robotic arm to insonify the tank from many locations. Several floats were placed in the tank as acoustic targets at diagonal ranges of approximately one meter. The accelerometer data show the direct source wave as well as the target scattered waves and reflections from the nearby water surface, tank bottom and sides. Without resorting to the usual methods of seismic imaging, which in this case is only two dimensional and relied entirely on the use of a synthetic source aperture, the two targets, the tank walls, the tank bottom, and the water surface were imaged. A directional ambiguity inherent to vector sensors is removed by using collocated hydrophone data. Although this experiment was in a very simple environment, it suggests that 3-D seismic surveys may be achieved with vector sensors using the same logistics as a 2-D survey that uses conventional hydrophones. This work was supported by the Office of Naval Research, program element 61153N.

  2. Depth map generation from geometry and motion

    NASA Astrophysics Data System (ADS)

    Li, Qianmin; Ge, Chenyang; Ren, Pengju; Yao, Huimin

    2013-07-01

    As the demand for 3DTV keep increasing these years, the conversion from exist 2D videos to 3D ones becomes a new area of research. Depth map generation plays a key point in the process. Two most important clues of depth are geometry of the scene and motion vector. This paper presents an algorithm of depth map generation, which intends to get the depth map combines two aspects of information. Compared to the previous work, our method is improved in finding vanishing point, detect motion vectors, and depth map generation.

  3. Reliable camera motion estimation from compressed MPEG videos using machine learning approach

    NASA Astrophysics Data System (ADS)

    Wang, Zheng; Ren, Jinchang; Wang, Yubin; Sun, Meijun; Jiang, Jianmin

    2013-05-01

    As an important feature in characterizing video content, camera motion has been widely applied in various multimedia and computer vision applications. A novel method for fast and reliable estimation of camera motion from MPEG videos is proposed, using support vector machine for estimation in a regression model trained on a synthesized sequence. Experiments conducted on real sequences show that the proposed method yields much improved results in estimating camera motions while the difficulty in selecting valid macroblocks and motion vectors is skipped.

  4. Cooperative phenomena in the perception of motion direction.

    PubMed

    Williams, D; Phillips, G

    1987-05-01

    A percept of global coherent motion can result from the combination of many different localized motion vectors. We report here evidence of hysteresis in the perception of this global motion, obtained with random-dot cinematograms. The hysteresis characteristics are relatively robust with respect to changes in dot density, display area, and location. Changing the directional content of the stimulus, however, did alter the hysteresis profile in a manner consistent with a model incorporating cooperative interactions among direction-selective motion mechanisms. Our results lend further support to a cooperative interpretation of motion results lend further support to a cooperative interpretation of motion perception in random-dot cinematograms. PMID:3598741

  5. Frame rate up conversion via Bayesian motion estimation

    NASA Astrophysics Data System (ADS)

    Wang, Yue; Ma, Siwei; Gao, Wen

    2010-07-01

    In this paper, a novel block-based motion compensated frame interpolation (MCI) algorithm is proposed to enhance the temporal resolution of video sequences. We formulated motion estimation into MAP framework, and solved it via Bayesian belief propagation. By effectively incorporating a priori knowledge of the motion field and optimizing the whole motion field synchronously, it could derive more accurate motion vectors than traditional methods. Finally, adaptive overlapped block motion compensation (OBMC) is used to reduce blocking artifacts. Experimental results show that the proposed method outperforms other methods in both objective and subjective quality.

  6. Cloud Infrastructure & Applications - CloudIA

    NASA Astrophysics Data System (ADS)

    Sulistio, Anthony; Reich, Christoph; Doelitzscher, Frank

    The idea behind Cloud Computing is to deliver Infrastructure-as-a-Services and Software-as-a-Service over the Internet on an easy pay-per-use business model. To harness the potentials of Cloud Computing for e-Learning and research purposes, and to small- and medium-sized enterprises, the Hochschule Furtwangen University establishes a new project, called Cloud Infrastructure & Applications (CloudIA). The CloudIA project is a market-oriented cloud infrastructure that leverages different virtualization technologies, by supporting Service-Level Agreements for various service offerings. This paper describes the CloudIA project in details and mentions our early experiences in building a private cloud using an existing infrastructure.

  7. Imaging vector fields using Line Integral Convolution

    SciTech Connect

    Cabral, B.; Leedom, L.C.

    1993-03-01

    Imaging vector fields has applications in science, art, image processing and special effects. An effective new approach is to use linear and curvilinear filtering techniques to locally blur textures along a vector field. This approach builds on several previous texture generation and filtering techniques. It is, however, unique because it is local, one-dimensional and independent of any predefined geometry or texture. The technique is general and capable of imaging arbitrary two- and three-dimensional vector fields. The local one-dimensional nature of the algorithm lends itself to highly parallel and efficient implementations. Furthermore, the curvilinear filter is capable of rendering detail on very intricate vector fields. Combining this technique with other rendering and image processing techniques -- like periodic motion filtering -- results in richly informative and striking images. The technique can also produce novel special effects.

  8. Dust cloud manipulation in microgravity experiments

    NASA Astrophysics Data System (ADS)

    Vedernikov, Andrei; Blum, Jurgen; Ingo Von Borstel, Olaf; Schraepler, Rainer; Balapanov, Daniyar; Cecere, Anselmo

    The European Space Agency’s scientific program Interactions in Cosmic and Atmospheric Particle Systems (ICAPS) [1] attributed for the International Space Station is aimed at increasing our knowledge about dust agglomeration in astrophysical processes mostly related to proto-planetary matter formation. These processes are simulated experimentally in clouds initially composed of about micrometre-sized solid particles. Relatively low gas pressure provides intensive enough particle Brownian motion but considerably reduces the experimentation time at normal gravity. Microgravity removes this problem but long duration experiments result in cloud depletion due to grain diffusion to the chamber walls and particle number density decrease due to agglomeration. The main problem comes from the fact that residual forces quickly sweep away the cloud from the observation volume thus drastically reducing the experiment duration. We developed different cloud manipulation systems that solve these problems and provide additional research opportunities in investigation of dust clouds. Particularly, they counterbalance external perturbations and solve the most challenging task of the increase of particle number concentration (cloud squeezing). There are several driving forces that may be used separately or in combination. Thermophoresis and gas flows induced by thermal creep are most favourable for cloud manipulation because they are nearly independent from particle properties. Electrostatic force allows detect charged particles, while photophoresis is sensitive to particle dimensions. The system provides two main regimes - 1) cloud positioning or displacement and 2) dynamic trapping. In absence of repulsive forces between particles the latter regime leads to cloud squeezing and intensive forced particle agglomeration. The cloud manipulation system additionally provides temperature stabilization or, on the contrary, high temperature variation in the observation volume; formation of

  9. Venus: Cloud level circulation during 1982 as determined from Pioneer cloud photopolarimeter images. II - Solar longitude dependent circulation

    NASA Technical Reports Server (NTRS)

    Limaye, Sanjay S.

    1988-01-01

    Pioneer Venus Orbiter images obtained in 1982 indicate a marked solar-locked dependence of cloud level circulation in both averaged cloud motions and cloud layer UV reflectivity. An apparent relationship is noted between horizontal divergence and UV reflectivity: the highest reflectivities are associated with regions of convergence at high latitudes, while lower values are associated with equatorial latitude regions where the motions are divergent. In solar-locked coordinates, the rms deviation of normalized UV brightness is higher at 45-deg latitudes than in equatorial regions.

  10. The Advancement of Intraplate Tectonic Motion Detection by the Use of Atmospherically Corrected InSAR Time-series and its Decomposition into a 3D Field Vector in South-East Sicily, Italy.

    NASA Astrophysics Data System (ADS)

    Vollrath, A.; Bekaert, D. P.; Bonforte, A.; Guglielmino, F.; Hooper, A. J.; Stramondo, S.; Zucca, F.

    2014-12-01

    This study provides insights into the advancements gained by applying a tropospheric correction to a time-series InSAR small baseline network processed using the StaMPS software for the Hyblean Plateau in south-east Sicily, Italy. The contribution of the atmosphere is one of the major error sources in repeat-pass InSAR in general. For time-series analysis spatial and temporal "filtering" of the interferometric phase can be used to address atmospheric signals. This however might be at the cost of smoothing and removal of the "tectonic deformation". We applied a tropospheric correction to each interferogram based on estimates of the ERA-Interim weather model, provided by the European Center for Medium-Range Weather Forecast (ECMWF). This approach is part of the InSAR Atmospheric Correction Toolbox (Bekaert et al, in prep) and converts the tropospheric water vapor content into the phase-delay of the radar line-of-sight. For the analysis we used 49 descending and 58 ascending Envisat SAR images, which cover the time period from 2003 until 2010. In addition, we have processed 30 SAR images of RADARSAT-2 for the period between 2010-2012. Furthermore, we used the different viewing geometries and the integration of GPS data to decompose the single line-of-sight velocities into a 3-dimensional field vector by applying the SISTEM approach (Guglielmino et al. 2011). First results reveal that the atmospherically corrected data retain the deformation signal along geological structures like the Scicli-Ragusa fault whilst the standard filtering approach is canceling out these very slow deformation patterns. Simultaneously, the variability of the signal in space is diminished and thus gives more confidence on the deformation patterns observed by the SAR. Consequently, the decomposition of the line-of-sight velocities and the integration with the GPS data allows us to retrieve a more realistic deformation field.

  11. Multivariate respiratory motion prediction

    NASA Astrophysics Data System (ADS)

    Dürichen, R.; Wissel, T.; Ernst, F.; Schlaefer, A.; Schweikard, A.

    2014-10-01

    In extracranial robotic radiotherapy, tumour motion is compensated by tracking external and internal surrogates. To compensate system specific time delays, time series prediction of the external optical surrogates is used. We investigate whether the prediction accuracy can be increased by expanding the current clinical setup by an accelerometer, a strain belt and a flow sensor. Four previously published prediction algorithms are adapted to multivariate inputs—normalized least mean squares (nLMS), wavelet-based least mean squares (wLMS), support vector regression (SVR) and relevance vector machines (RVM)—and evaluated for three different prediction horizons. The measurement involves 18 subjects and consists of two phases, focusing on long term trends (M1) and breathing artefacts (M2). To select the most relevant and least redundant sensors, a sequential forward selection (SFS) method is proposed. Using a multivariate setting, the results show that the clinically used nLMS algorithm is susceptible to large outliers. In the case of irregular breathing (M2), the mean root mean square error (RMSE) of a univariate nLMS algorithm is 0.66 mm and can be decreased to 0.46 mm by a multivariate RVM model (best algorithm on average). To investigate the full potential of this approach, the optimal sensor combination was also estimated on the complete test set. The results indicate that a further decrease in RMSE is possible for RVM (to 0.42 mm). This motivates further research about sensor selection methods. Besides the optical surrogates, the sensors most frequently selected by the algorithms are the accelerometer and the strain belt. These sensors could be easily integrated in the current clinical setup and would allow a more precise motion compensation.

  12. Early, local motion signals generate directional preferences in depth ordering of transparent motion.

    PubMed

    Schütz, Alexander C; Mamassian, Pascal

    2016-08-01

    Superposition of two dot clouds moving in different directions results in the perception of two transparent layers. Despite the ambiguous depth order of the layers, there are consistent preferences to perceive the layer, which is moving either rightward or downward in front of the other layer. Here we investigated the origin of these depth order biases. For this purpose, we measured the interaction with stereoscopic disparity and the influence of global and local motion properties. Motion direction and stereoscopic disparity were equally effective in determining depth order at a disparity of one arcmin. Global motion properties, such as the aperture location in the visual field or the aperture's motion direction did not affect directional biases. Local motion properties however were effective. When the moving elements were oriented lines rather than dots, the directional biases were shifted towards the direction orthogonal to the lines rather than the actual motion direction of the lines. Therefore, depth order was determined before the aperture problem was fully resolved. Varying the duration of the stimuli, we found that the time constant of the aperture problem was much lower for depth order than for perceived motion direction. Altogether, our results indicate that depth order is determined in one shot on the basis of an early motion signal, while perceived motion direction is continuously updated. Thus, depth ordering in transparent motion appears to be a surprisingly fast process, that relies on early, local motion signals and that precedes high-level motion analysis. PMID:27580044

  13. Method and system for non-linear motion estimation

    NASA Technical Reports Server (NTRS)

    Lu, Ligang (Inventor)

    2011-01-01

    A method and system for extrapolating and interpolating a visual signal including determining a first motion vector between a first pixel position in a first image to a second pixel position in a second image, determining a second motion vector between the second pixel position in the second image and a third pixel position in a third image, determining a third motion vector between one of the first pixel position in the first image and the second pixel position in the second image, and the second pixel position in the second image and the third pixel position in the third image using a non-linear model, determining a position of the fourth pixel in a fourth image based upon the third motion vector.

  14. Reduced Vector Preisach Model

    NASA Technical Reports Server (NTRS)

    Patel, Umesh D.; Torre, Edward Della; Day, John H. (Technical Monitor)

    2002-01-01

    A new vector Preisach model, called the Reduced Vector Preisach model (RVPM), was developed for fast computations. This model, derived from the Simplified Vector Preisach model (SVPM), has individual components that like the SVPM are calculated independently using coupled selection rules for the state vector computation. However, the RVPM does not require the rotational correction. Therefore, it provides a practical alternative for computing the magnetic susceptibility using a differential approach. A vector version, using the framework of the DOK model, is implemented. Simulation results for the reduced vector Preisach model are also presented.

  15. Ice Clouds in Martian Arctic (Accelerated Movie)

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Clouds scoot across the Martian sky in a movie clip consisting of 10 frames taken by the Surface Stereo Imager on NASA's Phoenix Mars Lander.

    This clip accelerates the motion. The camera took these 10 frames over a 10-minute period from 2:52 p.m. to 3:02 p.m. local solar time at the Phoenix site during Sol 94 (Aug. 29), the 94th Martian day since landing.

    Particles of water-ice make up these clouds, like ice-crystal cirrus clouds on Earth. Ice hazes have been common at the Phoenix site in recent days.

    The camera took these images as part of a campaign by the Phoenix team to see clouds and track winds. The view is toward slightly west of due south, so the clouds are moving westward or west-northwestward.

    The clouds are a dramatic visualization of the Martian water cycle. The water vapor comes off the north pole during the peak of summer. The northern-Mars summer has just passed its peak water-vapor abundance at the Phoenix site. The atmospheric water is available to form into clouds, fog and frost, such as the lander has been observing recently.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  16. Retrieving co-occurring cloud and precipitation properties of warm marine boundary layer clouds with A-Train data

    NASA Astrophysics Data System (ADS)

    Mace, Gerald G.; Avey, Stephanie; Cooper, Steven; Lebsock, Matthew; Tanelli, Simone; Dobrowalski, Greg

    2016-04-01

    In marine boundary layer (MBL) clouds the formation of precipitation from the cloud droplet distribution in the presence of variable aerosol plays a fundamental role in determining the coupling of these clouds to their environment and ultimately to the climate system. Here the degree to which A-Train satellite measurements can diagnose simultaneously occurring cloud and precipitation properties in MBL clouds is examined. Beginning with the measurements provided by CloudSat and Moderate Resolution Imaging Spectroradiometer (including a newly available microwave brightness temperature from CloudSat), and a climatology of MBL cloud properties from past field campaigns, an assumption is made that any hydrometeor volume could contain both cloud droplet and precipitation droplet modes. Bayesian optimal estimation is then used to derive atmospheric states by inverting a measurement vector carefully accounting for uncertainties due to instrument noise, forward model error, and assumptions. It is found that in many cases where significant precipitation coexists with cloud, due to forward model error driven by uncertainties in assumptions, the uncertainty in retrieved cloud properties is greater than the variance in the prior climatology. It is often necessary to average several thousand (hundred) precipitating (weakly precipitating) profiles to obtain meaningful information regarding the properties important to microphysical processes. Regardless, if such process level information is deemed necessary for better constraining predictive models of the climate system, measurement systems specifically designed to accomplish such retrievals must be considered for the future.

  17. Understanding Singular Vectors

    ERIC Educational Resources Information Center

    James, David; Botteron, Cynthia

    2013-01-01

    matrix yields a surprisingly simple, heuristical approximation to its singular vectors. There are correspondingly good approximations to the singular values. Such rules of thumb provide an intuitive interpretation of the singular vectors that helps explain why the SVD is so…

  18. The vector ruling protractor

    NASA Technical Reports Server (NTRS)

    Zahm, A F

    1924-01-01

    The theory, structure and working of a vector slide rule is presented in this report. This instrument is used for determining a vector in magnitude and position when given its components and its moment about a point in their plane.

  19. Vector polarons in a degenerate electron system

    NASA Astrophysics Data System (ADS)

    Clougherty, Dennis P.; Foell, Charles A.

    2004-08-01

    We consider a one-dimensional model of an electron in a doubly (or nearly) degenerate band that interacts with elastic distortions. We show that the electron equations of motion reduce to a set of coupled nonlinear Schrödinger equations. For the case of interband electron-phonon coupling stemming from local Jahn-Teller interactions, multicomponent self-localized polaron solutions-vector polarons- are described and classified. The phase diagram for the different types of vector polarons in this model is presented. By interpreting the components of the orbital doublet as those of spin- (1)/(2) , our results can also be used to describe bound magnetic polarons.

  20. Teaching Universal Gravitation with Vector Games

    NASA Astrophysics Data System (ADS)

    Lowry, Matthew

    2008-12-01

    Like many high school and college physics teachers, I have found playing vector games to be a useful way of illustrating the concepts of inertia, velocity, and acceleration. Like many, I have also had difficulty in trying to get students to understand Newton's law of universal gravitation, specifically the inverse-square law and its application to motion. In this paper, I'll outline a way to address this problem through use of a vector game. The inspiration for this idea came from a January 1998 article in The Physics Teacher by Michael Vinson entitled "Space Race: A Game of Physics Adventure."

  1. Restart 68000 vector remapping

    SciTech Connect

    Gustin, J.

    1984-05-03

    The circuit described allows power-on-reset (POR) vector fetch from ROM for a 68000 microprocessor. It offers programmability of exception vectors, including the restart vector. This method eliminates the need for high-resolution, address-decoder peripheral circuitry.

  2. Rhotrix Vector Spaces

    ERIC Educational Resources Information Center

    Aminu, Abdulhadi

    2010-01-01

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

  3. MATRIX AND VECTOR SERVICES

    Energy Science and Technology Software Center (ESTSC)

    2001-10-18

    PETRA V2 provides matrix and vector services and the ability construct, query, and use matrix and vector objects that are used and computed by TRILINOS solvers. It provides all basic matr5ix and vector operations for solvers in TRILINOS.

  4. Insulated Foamy Viral Vectors.

    PubMed

    Browning, Diana L; Collins, Casey P; Hocum, Jonah D; Leap, David J; Rae, Dustin T; Trobridge, Grant D

    2016-03-01

    Retroviral vector-mediated gene therapy is promising, but genotoxicity has limited its use in the clinic. Genotoxicity is highly dependent on the retroviral vector used, and foamy viral (FV) vectors appear relatively safe. However, internal promoters may still potentially activate nearby genes. We developed insulated FV vectors, using four previously described insulators: a version of the well-studied chicken hypersensitivity site 4 insulator (650cHS4), two synthetic CCCTC-binding factor (CTCF)-based insulators, and an insulator based on the CCAAT box-binding transcription factor/nuclear factor I (7xCTF/NF1). We directly compared these insulators for enhancer-blocking activity, effect on FV vector titer, and fidelity of transfer to both proviral long terminal repeats. The synthetic CTCF-based insulators had the strongest insulating activity, but reduced titers significantly. The 7xCTF/NF1 insulator did not reduce titers but had weak insulating activity. The 650cHS4-insulated FV vector was identified as the overall most promising vector. Uninsulated and 650cHS4-insulated FV vectors were both significantly less genotoxic than gammaretroviral vectors. Integration sites were evaluated in cord blood CD34(+) cells and the 650cHS4-insulated FV vector had fewer hotspots compared with an uninsulated FV vector. These data suggest that insulated FV vectors are promising for hematopoietic stem cell gene therapy. PMID:26715244

  5. Demonstrating the Direction of Angular Velocity in Circular Motion

    ERIC Educational Resources Information Center

    Demircioglu, Salih; Yurumezoglu, Kemal; Isik, Hakan

    2015-01-01

    Rotational motion is ubiquitous in nature, from astronomical systems to household devices in everyday life to elementary models of atoms. Unlike the tangential velocity vector that represents the instantaneous linear velocity (magnitude and direction), an angular velocity vector is conceptually more challenging for students to grasp. In physics…

  6. Quantication and analysis of respiratory motion from 4D MRI

    NASA Astrophysics Data System (ADS)

    Aizzuddin Abd Rahni, Ashrani; Lewis, Emma; Wells, Kevin

    2014-11-01

    It is well known that respiratory motion affects image acquisition and also external beam radiotherapy (EBRT) treatment planning and delivery. However often the existing approaches for respiratory motion management are based on a generic view of respiratory motion such as the general movement of organ, tissue or fiducials. This paper thus aims to present a more in depth analysis of respiratory motion based on 4D MRI for further integration into motion correction in image acquisition or image based EBRT. Internal and external motion was first analysed separately, on a per-organ basis for internal motion. Principal component analysis (PCA) was then performed on the internal and external motion vectors separately and the relationship between the two PCA spaces was analysed. The motion extracted from 4D MRI on general was found to be consistent with what has been reported in literature.

  7. The Oort cloud

    NASA Technical Reports Server (NTRS)

    Marochnik, Leonid S.; Mukhin, Lev M.; Sagdeev, Roald Z.

    1991-01-01

    Views of the large-scale structure of the solar system, consisting of the Sun, the nine planets and their satellites, changed when Oort demonstrated that a gigantic cloud of comets (the Oort cloud) is located on the periphery of the solar system. The following subject areas are covered: (1) the Oort cloud's mass; (2) Hill's cloud mass; (3) angular momentum distribution in the solar system; and (4) the cometary cloud around other stars.

  8. Registration algorithm of point clouds based on multiscale normal features

    NASA Astrophysics Data System (ADS)

    Lu, Jun; Peng, Zhongtao; Su, Hang; Xia, GuiHua

    2015-01-01

    The point cloud registration technology for obtaining a three-dimensional digital model is widely applied in many areas. To improve the accuracy and speed of point cloud registration, a registration method based on multiscale normal vectors is proposed. The proposed registration method mainly includes three parts: the selection of key points, the calculation of feature descriptors, and the determining and optimization of correspondences. First, key points are selected from the point cloud based on the changes of magnitude of multiscale curvatures obtained by using principal components analysis. Then the feature descriptor of each key point is proposed, which consists of 21 elements based on multiscale normal vectors and curvatures. The correspondences in a pair of two point clouds are determined according to the descriptor's similarity of key points in the source point cloud and target point cloud. Correspondences are optimized by using a random sampling consistency algorithm and clustering technology. Finally, singular value decomposition is applied to optimized correspondences so that the rigid transformation matrix between two point clouds is obtained. Experimental results show that the proposed point cloud registration algorithm has a faster calculation speed, higher registration accuracy, and better antinoise performance.

  9. Motion Simulator

    NASA Technical Reports Server (NTRS)

    1993-01-01

    MOOG, Inc. supplies hydraulic actuators for the Space Shuttle. When MOOG learned NASA was interested in electric actuators for possible future use, the company designed them with assistance from Marshall Space Flight Center. They also decided to pursue the system's commercial potential. This led to partnership with InterActive Simulation, Inc. for production of cabin flight simulators for museums, expositions, etc. The resulting products, the Magic Motion Simulator 30 Series, are the first electric powered simulators. Movements are computer-guided, including free fall to heighten the sense of moving through space. A projection system provides visual effects, and the 11 speakers of a digital laser based sound system add to the realism. The electric actuators are easier to install, have lower operating costs, noise, heat and staff requirements. The U.S. Space & Rocket Center and several other organizations have purchased the simulators.

  10. Cloud-Ground Interaction

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Released 30 June 2004 The atmosphere of Mars is a dynamic system. Water-ice clouds, fog, and hazes can make imaging the surface from space difficult. Dust storms can grow from local disturbances to global sizes, through which imaging is impossible. Seasonal temperature changes are the usual drivers in cloud and dust storm development and growth.

    Eons of atmospheric dust storm activity has left its mark on the surface of Mars. Dust carried aloft by the wind has settled out on every available surface; sand dunes have been created and moved by centuries of wind; and the effect of continual sand-blasting has modified many regions of Mars, creating yardangs and other unusual surface forms.

    This image of the North Polar water-ice clouds shows how surface topography can affect the linear form. Notice that the crater at the bottom of the image is causing a deflection in the linear form.

    Image information: VIS instrument. Latitude 68.4, Longitude 100.7 East (259.3 West). 38 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the

  11. Animation of orthogonal texture patterns for vector field visualization.

    PubMed

    Bachthaler, Sven; Weiskopf, Daniel

    2008-01-01

    This paper introduces orthogonal vector field visualization on 2D manifolds: a representation by lines that are perpendicular to the input vector field. Line patterns are generated by line integral convolution (LIC). This visualization is combined with animation based on motion along the vector field. This decoupling of the line direction from the direction of animation allows us to choose the spatial frequencies along the direction of motion independently from the length scales along the LIC line patterns. Vision research indicates that local motion detectors are tuned to certain spatial frequencies of textures, and the above decoupling enables us to generate spatial frequencies optimized for motion perception. Furthermore, we introduce a combined visualization that employs orthogonal LIC patterns together with conventional, tangential streamline LIC patterns in order to benefit from the advantages of these two visualization approaches. In addition, a filtering process is described to achieve a consistent and temporally coherent animation of orthogonal vector field visualization. Different filter kernels and filter methods are compared and discussed in terms of visualization quality and speed. We present respective visualization algorithms for 2D planar vector fields and tangential vector fields on curved surfaces, and demonstrate that those algorithms lend themselves to efficient and interactive GPU implementations. PMID:18467751

  12. MGRA: Motion Gesture Recognition via Accelerometer

    PubMed Central

    Hong, Feng; You, Shujuan; Wei, Meiyu; Zhang, Yongtuo; Guo, Zhongwen

    2016-01-01

    Accelerometers have been widely embedded in most current mobile devices, enabling easy and intuitive operations. This paper proposes a Motion Gesture Recognition system (MGRA) based on accelerometer data only, which is entirely implemented on mobile devices and can provide users with real-time interactions. A robust and unique feature set is enumerated through the time domain, the frequency domain and singular value decomposition analysis using our motion gesture set containing 11,110 traces. The best feature vector for classification is selected, taking both static and mobile scenarios into consideration. MGRA exploits support vector machine as the classifier with the best feature vector. Evaluations confirm that MGRA can accommodate a broad set of gesture variations within each class, including execution time, amplitude and non-gestural movement. Extensive evaluations confirm that MGRA achieves higher accuracy under both static and mobile scenarios and costs less computation time and energy on an LG Nexus 5 than previous methods. PMID:27089336

  13. MGRA: Motion Gesture Recognition via Accelerometer.

    PubMed

    Hong, Feng; You, Shujuan; Wei, Meiyu; Zhang, Yongtuo; Guo, Zhongwen

    2016-01-01

    Accelerometers have been widely embedded in most current mobile devices, enabling easy and intuitive operations. This paper proposes a Motion Gesture Recognition system (MGRA) based on accelerometer data only, which is entirely implemented on mobile devices and can provide users with real-time interactions. A robust and unique feature set is enumerated through the time domain, the frequency domain and singular value decomposition analysis using our motion gesture set containing 11,110 traces. The best feature vector for classification is selected, taking both static and mobile scenarios into consideration. MGRA exploits support vector machine as the classifier with the best feature vector. Evaluations confirm that MGRA can accommodate a broad set of gesture variations within each class, including execution time, amplitude and non-gestural movement. Extensive evaluations confirm that MGRA achieves higher accuracy under both static and mobile scenarios and costs less computation time and energy on an LG Nexus 5 than previous methods. PMID:27089336

  14. Investigation of water vapor motion winds from geostationary satellites

    NASA Technical Reports Server (NTRS)

    Velden, Christopher S.; Nieman, Steven J.; Wanzong, Steven

    1994-01-01

    Water vapor imagery from geostationary satellites has been available for over a decade. These data are used extensively by operational analysts and forecasters, mainly in a qualitative mode (Weldon and Holmes 1991). In addition to qualitative applications, motions deduced in animated water vapor imagery can be used to infer wind fields in cloudless regimes, thereby augmenting the information provided by cloud-drift wind vectors. Early attempts at quantifying the data by tracking features in water vapor imagery met with modest success (Stewart et al. 1985; Hayden and Stewart 1987). More recently, automated techniques have been developed and refined, and have resulted in upper-level wind observations comparable in quality to current operational cloud-tracked winds (Laurent 1993). In a recent study by Velden et al. (1993) it was demonstrated that wind sets derived from Meteosat-3 (M-3) water vapor imagery can provide important environmental wind information in data void areas surrounding tropical cyclones, and can positively impact objective track forecasts. M-3 was repositioned to 75W by the European Space Agency in 1992 in order to provide complete coverage of the Atlantic Ocean. Data from this satellite are being transmitted to the U.S. for operational use. Compared with the current GOES-7 (G-7) satellite (positioned near 112W), the M-3 water vapor channel contains a superior horizontal resolution (5 km vs. 16 km ). In this paper, we examine wind sets derived using automated procedures from both GOES-7 and Meteosat-3 full disk water vapor imagery in order to assess this data as a potentially important source of large-scale wind information. As part of a product demonstration wind sets were produced twice a day at CIMSS during a six-week period in March and April (1994). These data sets are assessed in terms of geographic coverage, statistical accuracy, and meteorological impact through preliminary results of numerical model forecast studies.

  15. Covariantized vector Galileons

    NASA Astrophysics Data System (ADS)

    Hull, Matthew; Koyama, Kazuya; Tasinato, Gianmassimo

    2016-03-01

    Vector Galileons are ghost-free systems containing higher derivative interactions of vector fields. They break the vector gauge symmetry, and the dynamics of the longitudinal vector polarizations acquire a Galileon symmetry in an appropriate decoupling limit in Minkowski space. Using an Arnowitt-Deser-Misner approach, we carefully reconsider the coupling with gravity of vector Galileons, with the aim of studying the necessary conditions to avoid the propagation of ghosts. We develop arguments that put on a more solid footing the results previously obtained in the literature. Moreover, working in analogy with the scalar counterpart, we find indications for the existence of a "beyond Horndeski" theory involving vector degrees of freedom that avoids the propagation of ghosts thanks to secondary constraints. In addition, we analyze a Higgs mechanism for generating vector Galileons through spontaneous symmetry breaking, and we present its consistent covariantization.

  16. Diffuse Reflection of Laser Light From Clouds

    NASA Technical Reports Server (NTRS)

    Cahalan, R. F.; Davis, A.; McGill, M.

    1999-01-01

    Laser light reflected from an aqueous suspension of particles or "cloud" with known thickness and particle size distribution defines the "cloud radiative Green's function", G. G is sensitive to cloud thickness, allowing retrieval of that important quantity. We describe a laboratory simulation of G, useful in design of an offbeam Lidar instrument for remote sensing of cloud thickness. Clouds of polystyrene microspheres suspended in water are analogous to real clouds of water droplets suspended in air. The size distribution extends from 0.5 microns to 25 microns, roughly lognormal, similar to real clouds. Density of suspended spheres is adjusted so photon mean-free-path is about 10 cm, 1000 times smaller than in real clouds. The light source is a Nd:YAG laser at 530 nm. Detectors are flux and photon-counting PMTs, with a glass probe for precise positioning. A Labview 5 VI controls position and data acquisition, via an NI Motion Control board connected to a stepper motor driving an Edmund linear slider,and a 16-channel 16-bit NI-DAQ board. The stepper motor is accurate to 10 microns. Step size is selectable. Far from the beam, the rate of exponential increase in the beam direction scales as expected from diffusion theory, linearly with cloud thickness, and inversely as the square root of the reduced optical thickness, independent of particle size. Nearer the beam the signal increases faster than exponential and depends on particle size. Results verify 3D Monte Carlo simulations that demonstrate detectability of remotely sensed offbeam returns, without filters at night, with narrow bandpass filter in day.

  17. Cloud CCN feedback

    SciTech Connect

    Hudson, J.G.

    1992-12-31

    Cloud microphysics affects cloud albedo precipitation efficiency and the extent of cloud feedback in response to global warming. Compared to other cloud parameters, microphysics is unique in its large range of variability and the fact that much of the variability is anthropogenic. Probably the most important determinant of cloud microphysics is the spectra of cloud condensation nuclei (CCN) which display considerable variability and have a large anthropogenic component. When analyzed in combination three field observation projects display the interrelationship between CCN and cloud microphysics. CCN were measured with the Desert Research Institute (DRI) instantaneous CCN spectrometer. Cloud microphysical measurements were obtained with the National Center for Atmospheric Research Lockheed Electra. Since CCN and cloud microphysics each affect the other a positive feedback mechanism can result.

  18. Motion analysis of artery pulsation in neonatal cranial ultrasonogram

    NASA Astrophysics Data System (ADS)

    Fukuzawa, Masayuki; Kubo, Hiroki; Kitsunezuka, Yoshiki; Yamada, Masayoshi

    1999-05-01

    Using an optical-flow technique, we have quantitatively analyzed tissue motion due to artery pulsation accompanied with blood flow in a neonatal cranial ultrasonogram. The tissue motion vector was successfully calculated at each pixel in a series of echo images (32 frames, 640 X 480 pixels/frame, 8 bits/pixel, 33 ms/frame) taken in the brightness mode by using an ultrasound probe of 5.0 MHz. The optical-flow technique used was a gradient method combined with local optimization for 3 X 3 neighbors. From 2D mappings of tissue motion vectors and their time-sequence variations, it was found that the tissue motion due to artery pulsation revealed periodic to-and-fro motion synchronized with heartbeat (300 - 500 ms), clearly distinguishing from unwanted non-periodic motion due to the sway of neonatal head during diagnosis.

  19. Optimum instantaneous impulsive orbital injection to attain a specified asymptotic velocity vector.

    NASA Technical Reports Server (NTRS)

    Bean, W. C.

    1971-01-01

    A nalysis of the necessary conditions of Battin for instantaneous orbital injection, with consideration of the uniqueness of his solution, and of the further problem which arises in the degenerate case when radius vector and asymptotic vector are separated by 180 deg. It is shown that when the angular separation between radius vector and asymptotic velocity vector satisfies theta not equal to 180 deg, there are precisely two insertion-velocity vectors which permit attainment of the target asymptotic velocity vector, one yielding posigrade, the other retrograde motion. When theta equals to 180 deg, there is a family of insertion-velocity vectors which permit attainment of a specified asymptotic velocity vector with a unique insertion-velocity vector for every arbitrary orientation of a target unit angular momentum vector.

  20. Evaluation of Three Sensor Types for Particle Motion Measurement.

    PubMed

    Martin, Bruce; Zeddies, David G; Gaudet, Briand; Richard, Joel

    2016-01-01

    All fish sense acoustic particle motion; some species also sense pressure. Concern over the effects of anthropogenic sounds is increasing the need to monitor acoustic particle motion. Particle motion can be measured directly using vector sensors or calculated from pressure gradients. This article compares three devices that measure particle motion: a three-axis accelerometer, a three-axis velocity sensor, and two 4-element hydrophone arrays. A series of sounds (constant-wave tones, white noise, and Ricker wavelets) were played from a fixed-position projector. The particle motion of sounds from imploding light bulbs was also measured. PMID:26611019

  1. SinoCor: motion correction in SPECT

    NASA Astrophysics Data System (ADS)

    Mitra, Debasis; Eiland, Daniel; Abdallah, Mahmoud; Bouthcko, Rostyslav; Gullberg, Grant T.; Schechtmann, Norberto

    2012-02-01

    Motion is a serious artifact in Cardiac nuclear imaging because the scanning operation takes a long time. Since reconstruction algorithms assume consistent or stationary data the quality of resulting image is affected by motion, sometimes significantly. Even after adoption of the gold standard MoCo(R) algorithm from Cedars-Sinai by most vendors, heart motion remains a significant challenge. Also, any serious study in quantitative analysis necessitates correction for motion artifacts. It is generally recognized that human eye is a very sensitive tool for detecting motion. However, two reasons prevent such manual correction: (1) it is costly in terms of specialist's time, and (2) no such tool for manual correction is available currently. Previously, at SPIE-MIC'11, we presented a simple tool (SinoCor) that allows sinograms to be corrected manually or automatically. SinoCor performs correction of sinograms containing inter-frame patient or respiratory motions using rigid-body dynamics. The software is capable of detecting the patient motion and estimating the body-motion vector using scanning geometry parameters. SinoCor applies appropriate geometrical correction to all the frames subsequent to the frame when the movement has occurred in a manual or automated mode. For respiratory motion, it is capable of automatically smoothing small oscillatory (frame-wise local) movements. Lower order image moments are used to represent a frame and the required rigid body movement compensation is computed accordingly. Our current focus is on enhancement of SinoCor with the capability to automatically detect and compensate for intra-frame motion that causes motion blur on the respective frame. Intra-frame movements are expected in both patient and respiratory motions. For a controlled study we also have developed a motion simulator. A stable version of SinoCor is available under license from Lawrence Berkeley National Laboratory.

  2. Vector coding the finite volume procedure for the CYBER 205

    NASA Astrophysics Data System (ADS)

    Rizzi, A.

    The architecture of supercomputers and fundamental principles of vector programming in FORTRAN are reviewed, and vector coding and execution of the finite volume procedure on the CYBER 205 are described. With the proper structure given to the data base each coordinate direction can be differenced throughout the entire grid in one vector operation. Boundary conditions must be interleaved, which inhibits the concurrency of the overall scheme. No data motion together with inner-loop vectorization is advocated. The computed example of transonic flow separating from the sharp leading edge of a delta wing demonstrates the performance of the procedure. Vectors over 20,000 elements long are obtained, and a rate of over 50 megaflops sustained over the entire computation indicates the high degree of vectorization achieved.

  3. Index Sets and Vectorization

    SciTech Connect

    Keasler, J A

    2012-03-27

    Vectorization is data parallelism (SIMD, SIMT, etc.) - extension of ISA enabling the same instruction to be performed on multiple data items simultaeously. Many/most CPUs support vectorization in some form. Vectorization is difficult to enable, but can yield large efficiency gains. Extra programmer effort is required because: (1) not all algorithms can be vectorized (regular algorithm structure and fine-grain parallelism must be used); (2) most CPUs have data alignment restrictions for load/store operations (obey or risk incorrect code); (3) special directives are often needed to enable vectorization; and (4) vector instructions are architecture-specific. Vectorization is the best way to optimize for power and performance due to reduced clock cycles. When data is organized properly, a vector load instruction (i.e. movaps) can replace 'normal' load instructions (i.e. movsd). Vector operations can potentially have a smaller footprint in the instruction cache when fewer instructions need to be executed. Hybrid index sets insulate users from architecture specific details. We have applied hybrid index sets to achieve optimal vectorization. We can extend this concept to handle other programming models.

  4. Motion Information Inferring Scheme for Multi-View Video Coding

    NASA Astrophysics Data System (ADS)

    Koo, Han-Suh; Jeon, Yong-Joon; Jeon, Byeong-Moon

    This letter proposes a motion information inferring scheme for multi-view video coding motivated by the idea that the aspect of motion vector between the corresponding positions in the neighboring view pair is quite similar. The proposed method infers the motion information from the corresponding macroblock in the neighboring view after RD optimization with the existing prediction modes. This letter presents evaluation showing that the method significantly enhances the efficiency especially at high bit rates.

  5. A multi-dimensional vector spherical harmonics discrete ordinate method for atmospheric radiative transfer

    NASA Astrophysics Data System (ADS)

    Doicu, Adrian; Efremenko, Dmitry; Trautmann, Thomas

    2013-03-01

    The multi-dimensional scalar Spherical Harmonics Discrete Ordinate Method (SHDOM) is extended to the vector case. The vector model uses complex and real generalized spherical harmonics in the energetic representation of the Stokes vector, and retains some powerful features of the scalar model, as for example, the combination of the generalized spherical harmonic and the discrete ordinate representations of the radiance field, the use of a linear short characteristic method for computing the corner-point values of the Stokes vector, and the application of the adaptive grid technique. Results illustrating the accuracy of the vector model are shown for realistic simulated clouds.

  6. Formation of Bidisperse Particle Clouds

    NASA Astrophysics Data System (ADS)

    Er, Jenn Wei; Zhao, Bing; Law, Adrian W. K.; Adams, E. Eric

    2014-11-01

    When a group of dense particles is released instantaneously into water, their motion has been conceptualized as a circulating particle thermal (Ruggerber 2000). However, Wen and Nacamuli (1996) observed the formation of particle clumps characterized by a narrow, fast moving core shedding particles into wakes. They observed the clump formation even for particles in the non-cohesive range as long as the source Rayleigh number was large (Ra > 1E3) or equivalently the source cloud number (Nc) was small (Nc < 3.2E2). This physical phenomenon has been investigated by Zhao et al. (2014) through physical experiments. They proposed the theoretical support for Nc dependence and categorized the formation processes into cloud formation, transitional regime and clump formation. Previous works focused mainly on the behavior of monodisperse particles. The present study further extends the experimental investigation to the formation process of bidisperse particles. Experiments are conducted in a glass tank with a water depth of 90 cm. Finite amounts of sediments with various weight proportions between coarser and finer particles are released from a cylindrical tube. The Nc being tested ranges from 6E-3 to 9.9E-2, which covers all the three formation regimes. The experimental results showed that the introduction of coarse particles promotes cloud formation and reduce the losses of finer particles into the wake. More quantitative descriptions of the effects of source conditions on the formation processes will be presented during the conference.

  7. Role of Gravity Waves in Determining Cirrus Cloud Properties

    NASA Technical Reports Server (NTRS)

    OCStarr, David; Singleton, Tamara; Lin, Ruei-Fong

    2008-01-01

    Cirrus clouds are important in the Earth's radiation budget. They typically exhibit variable physical properties within a given cloud system and from system to system. Ambient vertical motion is a key factor in determining the cloud properties in most cases. The obvious exception is convectively generated cirrus (anvils), but even in this case, the subsequent cloud evolution is strongly influenced by the ambient vertical motion field. It is well know that gravity waves are ubiquitous in the atmosphere and occur over a wide range of scales and amplitudes. Moreover, researchers have found that inclusion of statistical account of gravity wave effects can markedly improve the realism of simulations of persisting large-scale cirrus cloud features. Here, we use a 1 -dimensional (z) cirrus cloud model, to systematically examine the effects of gravity waves on cirrus cloud properties. The model includes a detailed representation of cloud microphysical processes (bin microphysics and aerosols) and is run at relatively fine vertical resolution so as to adequately resolve nucleation events, and over an extended time span so as to incorporate the passage of multiple gravity waves. The prescribed gravity waves "propagate" at 15 m s (sup -1), with wavelengths from 5 to 100 km, amplitudes range up to 1 m s (sup -1)'. Despite the fact that the net gravity wave vertical motion forcing is zero, it will be shown that the bulk cloud properties, e.g., vertically-integrated ice water path, can differ quite significantly from simulations without gravity waves and that the effects do depend on the wave characteristics. We conclude that account of gravity wave effects is important if large-scale models are to generate realistic cirrus cloud property climatology (statistics).

  8. Collective motion

    NASA Astrophysics Data System (ADS)

    Vicsek, Tamás; Zafeiris, Anna

    2012-08-01

    We review the observations and the basic laws describing the essential aspects of collective motion - being one of the most common and spectacular manifestation of coordinated behavior. Our aim is to provide a balanced discussion of the various facets of this highly multidisciplinary field, including experiments, mathematical methods and models for simulations, so that readers with a variety of background could get both the basics and a broader, more detailed picture of the field. The observations we report on include systems consisting of units ranging from macromolecules through metallic rods and robots to groups of animals and people. Some emphasis is put on models that are simple and realistic enough to reproduce the numerous related observations and are useful for developing concepts for a better understanding of the complexity of systems consisting of many simultaneously moving entities. As such, these models allow the establishing of a few fundamental principles of flocking. In particular, it is demonstrated, that in spite of considerable differences, a number of deep analogies exist between equilibrium statistical physics systems and those made of self-propelled (in most cases living) units. In both cases only a few well defined macroscopic/collective states occur and the transitions between these states follow a similar scenario, involving discontinuity and algebraic divergences.

  9. Cloud Processed CCN Affect Cloud Microphysics

    NASA Astrophysics Data System (ADS)

    Hudson, J. G.; Noble, S. R., Jr.; Tabor, S. S.

    2015-12-01

    Variations in the bimodality/monomodality of CCN spectra (Hudson et al. 2015) exert opposite effects on cloud microphysics in two aircraft field projects. The figure shows two examples, droplet concentration, Nc, and drizzle liquid water content, Ld, against classification of CCN spectral modality. Low ratings go to balanced separated bimodal spectra, high ratings go to single mode spectra, strictly monomodal 8. Intermediate ratings go merged modes, e.g., one mode a shoulder of another. Bimodality is caused by mass or hygroscopicity increases that go only to CCN that made activated cloud droplets. In the Ice in Clouds Experiment-Tropical (ICE-T) small cumuli with lower Nc, greater droplet mean diameters, MD, effective radii, re, spectral widths, σ, cloud liquid water contents, Lc, and Ld were closer to more bimodal (lower modal ratings) below cloud CCN spectra whereas clouds with higher Nc, smaller MD, re, σ, and Ld were closer to more monomodal CCN (higher modal ratings). In polluted stratus clouds of the MArine Stratus/Stratocumulus Experiment (MASE) clouds that had greater Nc, and smaller MD, re, σ, Lc, and Ld were closer to more bimodal CCN spectra whereas clouds with lower Nc, and greater MD, re, σ, Lc, and Ld were closer to more monomodal CCN. These relationships are opposite because the dominant ICE-T cloud processing was coalescence whereas chemical transformations (e.g., SO2 to SO4) were dominant in MASE. Coalescence reduces Nc and thus also CCN concentrations (NCCN) when droplets evaporate. In subsequent clouds the reduced competition increases MD and σ, which further enhance coalescence and drizzle. Chemical transformations do not change Nc but added sulfate enhances droplet and CCN solubility. Thus, lower critical supersaturation (S) CCN can produce more cloud droplets in subsequent cloud cycles, especially for the low W and effective S of stratus. The increased competition reduces MD, re, and σ, which inhibit coalescence and thus reduce drizzle

  10. Vegetation forcing and convective motion

    SciTech Connect

    Hong, X.; Leach, M.J.; Raman, S.

    1995-04-01

    A large irrigated vegetation area in a semiarid or relatively dry location is a strong surface forcing of thermal circulations. Several observational studies have found that such thermally induced mesoscale circulation may contribute to the triggering and development of convective clouds. In the western United States, extensive areas of irrigated farmland are surrounded by hot, dry surfaces, such as a steppe. Substantial gradients of sensible heating in the horizontal direction lead to a {open_quotes}farm breeze{close_quotes} circulation from the cooler agricultural area to the warmer steppes found at Boardman, Oregon. These thermally forced circulations may trigger convection by the related convergence and updraft motion under favorable atmospheric conditions. The role of vegetative covering in convective motion is investigated using a mesoscale numerical model. Two- and three-dimensional simulations are described. The effects of atmospheric stability, moisture in the lower atmosphere, moisture in the upper atmosphere, and horizontal heating scale on thermally induced clouds are studied. The horizontal scale of inhomogeneity is also studied using the two-dimensional model. Finally, a realistic vegetation distribution similar to that of the Boardman Regional Flux Experiment is used in the three-dimensional simulations.

  11. Airborne observations of electric fields around growing and decaying cumulus clouds

    NASA Technical Reports Server (NTRS)

    Giori, K. L.; Nanevicz, J. E.

    1991-01-01

    Airborne electric field data were gathered in an atmospheric electrification study near Cape Canaveral, FL. A Learjet 36A was instrumented with eight electric field meters (mills) and five different particle probes. The local electric field enhancements at each field mill site were determined under lab conditions and verified using in-flight data. The overdetermined system of eight equations (one for each field mill) was solved using a weighted least squares algorithm to compute the magnitude and direction of the ambient electric field. The signal processing system allowed the measured data to be expressed in terms of earth coordinates, regardless of the attitude of the aircraft. Thus, it was possible to take maximum advantage of the Learjet's speed and maneuverability in studying the electric field structure in the vicinity of the clouds. Data gathered while circling just outside the boundary of a growing cumulus cloud show a nonsymmetric pattern of electric field strength. Field intensity grew rapidly over a period of less than 10 minutes. The observed direction of the ambient electric field vector can be explained by an ascending motion of the charge centers of a classic tripole model of a thunderstorm.

  12. Auditory motion affects visual biological motion processing.

    PubMed

    Brooks, A; van der Zwan, R; Billard, A; Petreska, B; Clarke, S; Blanke, O

    2007-02-01

    The processing of biological motion is a critical, everyday task performed with remarkable efficiency by human sensory systems. Interest in this ability has focused to a large extent on biological motion processing in the visual modality (see, for example, Cutting, J. E., Moore, C., & Morrison, R. (1988). Masking the motions of human gait. Perception and Psychophysics, 44(4), 339-347). In naturalistic settings, however, it is often the case that biological motion is defined by input to more than one sensory modality. For this reason, here in a series of experiments we investigate behavioural correlates of multisensory, in particular audiovisual, integration in the processing of biological motion cues. More specifically, using a new psychophysical paradigm we investigate the effect of suprathreshold auditory motion on perceptions of visually defined biological motion. Unlike data from previous studies investigating audiovisual integration in linear motion processing [Meyer, G. F. & Wuerger, S. M. (2001). Cross-modal integration of auditory and visual motion signals. Neuroreport, 12(11), 2557-2560; Wuerger, S. M., Hofbauer, M., & Meyer, G. F. (2003). The integration of auditory and motion signals at threshold. Perception and Psychophysics, 65(8), 1188-1196; Alais, D. & Burr, D. (2004). No direction-specific bimodal facilitation for audiovisual motion detection. Cognitive Brain Research, 19, 185-194], we report the existence of direction-selective effects: relative to control (stationary) auditory conditions, auditory motion in the same direction as the visually defined biological motion target increased its detectability, whereas auditory motion in the opposite direction had the inverse effect. Our data suggest these effects do not arise through general shifts in visuo-spatial attention, but instead are a consequence of motion-sensitive, direction-tuned integration mechanisms that are, if not unique to biological visual motion, at least not common to all types of

  13. The Evolution of Gas Clouds Falling in the Magnetized Galactic Halo: High-Velocity Clouds (HVCs) Originated in the Galactic Fountain

    NASA Astrophysics Data System (ADS)

    Kwak, Kyujin; Shelton, Robin L.; Raley, Elizabeth A.

    2009-07-01

    In the Galactic fountain scenario, supernovae and/or stellar winds propel material into the Galactic halo. As the material cools, it condenses into clouds. By using FLASH three-dimensional magnetohydrodynamic simulations, we model and study the dynamical evolution of these gas clouds after they form and begin to fall toward the Galactic plane. In our simulations, we assume that the gas clouds form at a height of z = 5 kpc above the Galactic midplane, then begin to fall from rest. We investigate how the cloud's evolution, dynamics, and interaction with the interstellar medium (ISM) are affected by the initial mass of the cloud. We find that clouds with sufficiently large initial densities (n >= 0.1 H atoms cm-3) accelerate sufficiently and maintain sufficiently large column densities as to be observed and identified as high-velocity clouds (HVCs) even if the ISM is weakly magnetized (1.3 μG). However, the ISM can provide noticeable resistance to the motion of a low-density cloud (n <= 0.01 H atoms cm-3) thus making it more probable that a low-density cloud will attain the speed of an intermediate-velocity cloud rather than the speed of an HVC. We also investigate the effects of various possible magnetic field configurations. As expected, the ISM's resistance is greatest when the magnetic field is strong and perpendicular to the motion of the cloud. The trajectory of the cloud is guided by the magnetic field lines in cases where the magnetic field is oriented diagonal to the Galactic plane. The model cloud simulations show that the interactions between the cloud and the ISM can be understood via analogy to the shock tube problem which involves shock and rarefaction waves. We also discuss accelerated ambient gas, streamers of material ablated from the clouds, and the cloud's evolution from a sphere-shaped to a disk- or cigar-shaped object.

  14. Cloud Computing for radiologists.

    PubMed

    Kharat, Amit T; Safvi, Amjad; Thind, Ss; Singh, Amarjit

    2012-07-01

    Cloud computing is a concept wherein a computer grid is created using the Internet with the sole purpose of utilizing shared resources such as computer software, hardware, on a pay-per-use model. Using Cloud computing, radiology users can efficiently manage multimodality imaging units by using the latest software and hardware without paying huge upfront costs. Cloud computing systems usually work on public, private, hybrid, or community models. Using the various components of a Cloud, such as applications, client, infrastructure, storage, services, and processing power, Cloud computing can help imaging units rapidly scale and descale operations and avoid huge spending on maintenance of costly applications and storage. Cloud computing allows flexibility in imaging. It sets free radiology from the confines of a hospital and creates a virtual mobile office. The downsides to Cloud computing involve security and privacy issues which need to be addressed to ensure the success of Cloud computing in the future. PMID:23599560

  15. Noctilucent Cloud Sightings

    NASA Video Gallery

    Polar Mesospheric Clouds form during each polar region's summer months in the coldest place in the atmosphere, 50 miles above Earth's surface. Noctilucent Clouds were first observed in 1885 by an a...

  16. Closed Small Cell Clouds

    Atmospheric Science Data Center

    2013-04-19

    article title:  Closed Small Cell Clouds in the South Pacific     ... the Multi-angle Imaging SpectroRadiometer (MISR). Closed cell clouds are formed under conditions of widespread sinking of the air above. ...

  17. Tvashtar in Motion

    NASA Technical Reports Server (NTRS)

    2007-01-01

    This five-frame sequence of New Horizons images captures the giant plume from Io's Tvashtar volcano. Snapped by the probe's Long Range Reconnaissance Imager (LORRI) as the spacecraft flew past Jupiter earlier this year, this first-ever 'movie' of an Io plume clearly shows motion in the cloud of volcanic debris, which extends 330 kilometers (200 miles) above the moon's surface. Only the upper part of the plume is visible from this vantage point -- the plume's source is 130 kilometers (80 miles) below the edge of Io's disk, on the far side of the moon.

    The appearance and motion of the plume is remarkably similar to an ornamental fountain on Earth, replicated on a gigantic scale. The knots and filaments that allow us to track the plume's motion are still mysterious, but this movie is likely to help scientists understand their origin, as well as provide unique information on the plume dynamics.

    Io's hyperactive nature is emphasized by the fact that two other volcanic plumes are also visible off the edge of Io's disk: Masubi at the 7 o'clock position, and a very faint plume, possibly from the volcano Zal, at the 10 o'clock position. Jupiter illuminates the night side of Io, and the most prominent feature visible on the disk is the dark horseshoe shape of the volcano Loki, likely an enormous lava lake. Boosaule Mons, which at 18 kilometers (11 miles) is the highest mountain on Io and one of the highest mountains in the solar system, pokes above the edge of the disk on the right side.

    The five images were obtained over an 8-minute span, with two minutes between frames, from 23:50 to 23:58 Universal Time on March 1, 2007. Io was 3.8 million kilometers (2.4 million miles) from New Horizons; the image is centered at Io coordinates 0 degrees north, 342 degrees west.

    The pictures were part of a sequence designed to look at Jupiter's rings, but planners included Io in the sequence because the moon was passing behind Jupiter's rings at the time.

  18. Symbolic computer vector analysis

    NASA Technical Reports Server (NTRS)

    Stoutemyer, D. R.

    1977-01-01

    A MACSYMA program is described which performs symbolic vector algebra and vector calculus. The program can combine and simplify symbolic expressions including dot products and cross products, together with the gradient, divergence, curl, and Laplacian operators. The distribution of these operators over sums or products is under user control, as are various other expansions, including expansion into components in any specific orthogonal coordinate system. There is also a capability for deriving the scalar or vector potential of a vector field. Examples include derivation of the partial differential equations describing fluid flow and magnetohydrodynamics, for 12 different classic orthogonal curvilinear coordinate systems.

  19. Computer animation of clouds

    SciTech Connect

    Max, N.

    1994-01-28

    Computer animation of outdoor scenes is enhanced by realistic clouds. I will discuss several different modeling and rendering schemes for clouds, and show how they evolved in my animation work. These include transparency-textured clouds on a 2-D plane, smooth shaded or textured 3-D clouds surfaces, and 3-D volume rendering. For the volume rendering, I will present various illumination schemes, including the density emitter, single scattering, and multiple scattering models.

  20. Cloud Scaling Properties and Cloud Parameterization

    NASA Technical Reports Server (NTRS)

    Cahalan, R. F.; Morcrette, J. J.

    1998-01-01

    Cloud liquid and cloud traction variability is studied as a function of horizontal scale in the ECMWF forecast model during several 10-day runs at the highest available model resolution, recently refined from approximately 60 km (T213) down to approximately 20 km (T639). At higher resolutions, model plane-parallel albedo biases are reduced, so that models may be tuned to have larger, more realistic, cloud liquid water amounts, However, the distribution of cloud liquid assumed -within- each gridbox, for radiative and thermodynamic computations, depends on ad hoc assumptions that are not necessarily consistent with observed scaling properties, or with scaling properties produced by the model at larger scales. To study the larger-scale cloud properties, ten locations on the Earth are chosen to coincide with locations having considerable surface data available for validation, and representing a variety of climatic regimes, scaling exponents are determined from a range or scales down to model resolution, and are re-computed every three hours, separately for low, medium and high clouds, as well as column-integrated cloudiness. Cloud variability fluctuates in time, due to diurnal, synoptic and other' processes, but scaling exponents are found to be relatively stable. various approaches are considered for applying computed cloud scaling to subgrid cloud distributions used for radiation, beyond simple random or maximal overlap now in common use. Considerably more work is needed to compare model cloud scaling with observations. This will be aided by increased availability of high-resolution surface, aircraft and satellite data, and by the increasing resolution of global models,

  1. Cloud Computing Explained

    ERIC Educational Resources Information Center

    Metz, Rosalyn

    2010-01-01

    While many talk about the cloud, few actually understand it. Three organizations' definitions come to the forefront when defining the cloud: Gartner, Forrester, and the National Institutes of Standards and Technology (NIST). Although both Gartner and Forrester provide definitions of cloud computing, the NIST definition is concise and uses…

  2. Descriptor for spatial distribution of motion activity for compressed video

    NASA Astrophysics Data System (ADS)

    Divakaran, Ajay; Sun, Huifang

    1999-12-01

    In this paper we present a new descriptor for spatial distribution of motion activity in video sequences. We use the magnitude of the motion vectors as a measure of the intensity of motion cavity in a macro-block. We construct a matrix Cmv consisting of the magnitudes of the motion vector for each macro-block of a given P frame. We compute the average magnitude of the motion vector per macro-block Cavg, and then use Cavg as a threshold on the matrix C by setting the elements of C that are less than Cavg to zero. We classify the runs of zeros into three categories based on length, and count the number of runs of each category in the matrix C. Our activity descriptor for a frame thus consists of four parameters viz. the average magnitude of the motion vectors and the numbers of runs of short, medium and long length. Since the feature extraction is in the compressed domain and simple, it is extremely fast. We have tested it on the MPEG-7 test content set, which consists of approximately 14 hours of MPEG-1 encoded video content of different kinds. We find that our descriptor enables fast and accurate indexing of video. It is robust to noise and changes in encoding parameters such as frame size, frame rate, encoding bit rate, encoding format etc. It is a low-level non-semantic descriptor that gives semantic matches within the same program, and is thus very suitable for applications such as video program browsing. We also find that indirect and computationally simpler measures of the magnitude of the motion vectors such as bits taken to encode the motion vectors, though less effective, also can be used in our run-length framework.

  3. Star-forming Substructure within Molecular Clouds

    NASA Astrophysics Data System (ADS)

    Di Francesco, James

    2013-03-01

    Wide-field far-infrared/submillimeter continuum maps of molecular clouds by the Herschel Space Observatory GBS and HOBYS surveys are revealing the star-forming substructures that lead to star formation in dense gas. In particular, these maps have revealed the central role in clouds of filaments, likely formed through turbulent motions. These filaments appear to be non-isothermal and fragment into cores only when their column densities exceed a stability threshold. Organizations of filament networks suggest the relative role of turbulence and gravity can be traced in different parts of a cloud, and filament intersections may lead to larger amounts of mass flow that form the precursors of high-mass stars or clusters.

  4. High velocity clouds in nearby disk galaxies

    NASA Technical Reports Server (NTRS)

    Schulman, Eric; Bregman, Joel N.; Roberts, Morton S.; Brinks, Elias

    1993-01-01

    Clouds of neutral hydrogen in our galaxy with the absolute value of v greater than 100 km/s cover approximately 10 percent of the sky to a limiting column density of 1 x 10(exp 18) cm(exp -2). These high velocity clouds (HVCs) may dominate the kinetic energy of neutral hydrogen in non-circular motion, and are an important though poorly understood component of galactic gas. It has been suggested that the HVCs can be reproduced by a combination of three phenomena: a galactic fountain driven by disk supernovae which would account for most of the HVCs, material tidally torn from the Magellanic Clouds, and an outer arm complex which is associated with the large scale structure of the warped galactic disk. We sought to detect HVCs in external galaxies in order to test the galactic fountain model.

  5. Inflation with a massive vector field nonminimally coupled to gravity

    NASA Astrophysics Data System (ADS)

    Bertolami, O.; Bessa, V.; Páramos, J.

    2016-03-01

    We study the possibility that inflation is driven by a massive vector field with S O (3 ) global symmetry nonminimally coupled to gravity. From an E3-invariant Robertson-Walker metric we propose an Ansatz for the vector field, allowing us to study the evolution of the system. We study the behavior of the equations of motion using the methods of the theory of dynamical systems and find exponential inflationary regimes.

  6. S-cone signals invisible to the motion system can improve motion extraction via grouping by color.

    PubMed

    Martinovic, Jasna; Meyer, Georg; Müller, Matthias M; Wuerger, Sophie M

    2009-01-01

    The purpose of this study was to test whether color-motion correlations carried by a pure color difference (S-cone component only) can be used to improve global motion extraction. We also examined the neural markers of color-motion correlation processing in event-related potentials. Color and motion information was dissociated using a two-colored random dot kinematogram, wherein coherent motion and motion noise differed from each other only in their S-cone component, with spatial and temporal parameters set so that global motion processing relied solely on a constant L-M component. Hence, when color and the local motion direction are correlated, more efficient segregation of coherent motion can only be brought about by the S-cone difference, and crucially, this S-cone component does not provide any effective input to a global motion mechanism but only changes the color appearance of the moving dots. The color contrasts (vector length in the S vs. L-M plane) of both the dots carrying coherent motion and the dots moving randomly were fixed at motion discrimination threshold to ensure equal effectiveness for motion extraction. In the behavioral experiment, participants were asked to discriminate between coherent and random motion, and d' was determined for three different conditions: uncorrelated, uncued correlated, and cued correlated. In the electroencephalographic experiment, participants discriminated direction of motion for uncued correlated and cued correlated conditions. Color-motion correlations were found to improve performance. Cueing a specific color also modulated the N1 component of the event-related potential, with sources in visual area middle temporal. We conclude that S-cone signals "invisible" to the motion system can influence the analysis by direction-selective motion mechanisms through grouping of local motion signals by color. This grouping mechanism must precede motion processing and is likely to be under attentional control. PMID:19366471

  7. Limited range of motion

    MedlinePlus

    Limited range of motion is a term meaning that a joint or body part cannot move through its normal range of motion. ... Motion may be limited because of a problem within the joint, swelling of tissue around the joint, ...

  8. Jovian Lightning and Moonlit Clouds

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Jovian lightning and moonlit clouds. These two images, taken 75 minutes apart, show lightning storms on the night side of Jupiter along with clouds dimly lit by moonlight from Io, Jupiter's closest moon. The images were taken in visible light and are displayed in shades of red. The images used an exposure time of about one minute, and were taken when the spacecraft was on the opposite side of Jupiter from the Earth and Sun. Bright storms are present at two latitudes in the left image, and at three latitudes in the right image. Each storm was made visible by multiple lightning strikes during the exposure. Other Galileo images were deliberately scanned from east to west in order to separate individual flashes. The images show that Jovian and terrestrial lightning storms have similar flash rates, but that Jovian lightning strikes are a few orders of magnitude brighter in visible light.

    The moonlight from Io allows the lightning storms to be correlated with visible cloud features. The latitude bands where the storms are seen seem to coincide with the 'disturbed regions' in daylight images, where short-lived chaotic motions push clouds to high altitudes, much like thunderstorms on Earth. The storms in these images are roughly one to two thousand kilometers across, while individual flashes appear hundreds of kilometer across. The lightning probably originates from the deep water cloud layer and illuminates a large region of the visible ammonia cloud layer from 100 kilometers below it.

    There are several small light and dark patches that are artifacts of data compression. North is at the top of the picture. The images span approximately 50 degrees in latitude and longitude. The lower edges of the images are aligned with the equator. The images were taken on October 5th and 6th, 1997 at a range of 6.6 million kilometers by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.

    The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for

  9. Self Motion Perception and Motion Sickness

    NASA Technical Reports Server (NTRS)

    Fox, Robert A. (Principal Investigator)

    1991-01-01

    The studies conducted in this research project examined several aspects of motion sickness in animal models. A principle objective of these studies was to investigate the neuroanatomy that is important in motion sickness with the objectives of examining both the utility of putative models and defining neural mechanisms that are important in motion sickness.

  10. 'Striated Delta' Clouds As Tracers Of Inertia-Gravity Wave Emission From Upper Jets And Extratropical Cyclones

    NASA Astrophysics Data System (ADS)

    Morgan, A. L.; Reeder, M. J.

    2012-12-01

    'Striated Delta' cloud formations are frequently tracers of upper-tropospheric inertia-gravity wave disturbances near the jet stream, coincident with rapid extratropical cyclogenesis (Feren, 1995). The investigation of source mechanisms in this context is important for better understanding of how and where large-amplitude inertia-gravity waves are generated, which propagate energy throughout the atmosphere and transfer it to the mean flow through breaking or attenuation processes. A seasonal study of twenty-eight Striated Delta events in the Australia/New Zealand region during May to September 2009 is analysed in the high-resolution ECMWF YOTC dataset. Mean composite analyses show that Striated Deltas occur in an upper-tropospheric environment of strong horizontal divergence, strong parcel accelerations, strong vertical motion and geostrophic imbalance. Synoptically, the Striated Delta cases occur in the poleward jet exit region near the axis of inflexion between an upstream upper trough and a downstream upper ridge. This is consistent with findings of previous studies regarding the synoptic environment characteristic of gravity wave generation. A Q-vector partitioning analysis suggests that flow curvature and advection of shear are the two greatest components to synoptic scale vertical motion forcing. The Q-Vector analysis also explains the characteristic triangular shape of the Striated Delta cloud formation. It is hypothesised that strong parcel accelerations due to curvature of the flow, as well as air parcel deceleration in the jet streak exit region, are responsible for the generation of inertia-gravity waves evident in the banding of Striated Delta clouds. Furthermore, deep convection is favoured in the poleward jet exit region by the ageostrophic circulation and is also thought to play a role in the generation of waves and the modulation of wavelengths. A distinct and interesting Striated Delta and extratropical cyclogenesis event from September 2009 is

  11. Corona Discharge in Clouds

    NASA Astrophysics Data System (ADS)

    Sin'kevich, A. A.; Dovgalyuk, Yu. A.

    2014-04-01

    We present a review of the results of theoretical studies and laboratory modeling of corona discharge initiation in clouds. The influence of corona discharges on the evolution of the cloud microstructure and electrification is analyzed. It is shown that corona discharges are initiated when large-size hydrometeors approach each other, whereas in some cases, corona discharges from crystals, ice pellets, and hailstones can appear. The corona discharges lead to significant air ionization, charging of cloud particles, and separation of charges in clouds and initiate streamers and lightnings. The influence of corona discharges on changes in the phase composition of clouds is analyzed.

  12. Cloud microstructure studies

    NASA Technical Reports Server (NTRS)

    Blau, H. H., Jr.; Fowler, M. G.; Chang, D. T.; Ryan, R. T.

    1972-01-01

    Over two thousand individual cloud droplet size distributions were measured with an optical cloud particle spectrometer flown on the NASA Convair 990 aircraft. Representative droplet spectra and liquid water content, L (gm/cu m) were obtained for oceanic stratiform and cumuliform clouds. For non-precipitating clouds, values of L range from 0.1 gm/cu m to 0.5 gm/cu m; with precipitation, L is often greater than 1 gm/cu m. Measurements were also made in a newly formed contrail and in cirrus clouds.

  13. Stability of Horndeski vector-tensor interactions

    SciTech Connect

    Jiménez, Jose Beltrán; Durrer, Ruth; Heisenberg, Lavinia; Thorsrud, Mikjel E-mail: ruth.durrer@unige.ch E-mail: mikjel.thorsrud@astro.uio.no

    2013-10-01

    We study the Horndeski vector-tensor theory that leads to second order equations of motion and contains a non-minimally coupled abelian gauge vector field. This theory is remarkably simple and consists of only 2 terms for the vector field, namely: the standard Maxwell kinetic term and a coupling to the dual Riemann tensor. Furthermore, the vector sector respects the U(1) gauge symmetry and the theory contains only one free parameter, M{sup 2}, that controls the strength of the non-minimal coupling. We explore the theory in a de Sitter spacetime and study the presence of instabilities and show that it corresponds to an attractor solution in the presence of the vector field. We also investigate the cosmological evolution and stability of perturbations in a general FLRW spacetime. We find that a sufficient condition for the absence of ghosts is M{sup 2} > 0. Moreover, we study further constraints coming from imposing the absence of Laplacian instabilities. Finally, we study the stability of the theory in static and spherically symmetric backgrounds (in particular, Schwarzschild and Reissner-Nordström-de Sitter). We find that the theory, quite generally, do have ghosts or Laplacian instabilities in regions of spacetime where the non-minimal interaction dominates over the Maxwell term. We also calculate the propagation speed in these spacetimes and show that superluminality is a quite generic phenomenon in this theory.

  14. Self-Motion Perception and Motion Sickness

    NASA Technical Reports Server (NTRS)

    Fox, Robert A.

    1991-01-01

    Motion sickness typically is considered a bothersome artifact of exposure to passive motion in vehicles of conveyance. This condition seldom has significant impact on the health of individuals because it is of brief duration, it usually can be prevented by simply avoiding the eliciting condition and, when the conditions that produce it are unavoidable, sickness dissipates with continued exposure. The studies conducted examined several aspects of motion sickness in animal models. A principle objective of these studies was to investigate the neuroanatomy that is important in motion sickness with the objectives of examining both the utility of putative models and defining neural mechanisms that are important in motion sickness.

  15. An Inexpensive Mechanical Model for Projectile Motion

    NASA Astrophysics Data System (ADS)

    Kagan, David

    2011-05-01

    As experienced physicists, we see the beauty and simplicity of projectile motion. It is merely the superposition of uniform linear motion along the direction of the initial velocity vector and the downward motion due to the constant acceleration of gravity. We see the kinematic equations as just the mathematical machinery to perform the calculations. What do our students see? Likely, most see no deeper than the operational understanding needed to use the kinematic equations. Described below is a device (shown in Fig. 1) that illustrates the physicist's view of projectile motion. It can be used as a classroom demonstration or as a project for your students, and it costs less than three dollars to make.

  16. Optimal quad-tree-based motion estimator

    NASA Astrophysics Data System (ADS)

    Schuster, Guido M.; Katsaggelos, Aggelos K.

    1996-09-01

    In this paper we propose an optimal quad-tree (QT)-based motion estimator for video compression. It is optimal in the sense that for a given bit budget for encoding the displacement vector field (DVF) and the QT segmentation, the scheme finds a DVF and a QT segmentation which minimizes the energy of the resulting displaced frame difference (DFD). We find the optimal QT decomposition and the optimal DVF jointly using the Lagrangian multiplier method and a multilevel dynamic program. The resulting DVF is spatially inhomogeneous since large blocks are used in areas with simple motion and small blocks in areas with complex motion. We present results with the proposed QT-based motion estimator which show that for the same DFD energy the proposed estimator uses about 30% fewer bits than the commonly used block matching algorithm.

  17. Hydrodynamics of Cloud Collisions in Two Dimensions: The Fate of Clouds in a Multiphase Medium

    NASA Astrophysics Data System (ADS)

    Miniati, Francesco; Jones, T. W.; Ferrara, Andrea; Ryu, Dongsu

    1997-12-01

    We have studied head-on collisions between equal-mass, mildly supersonic H I clouds (Mach number 1.5 with respect to the background medium) through high-resolution numerical simulations in two dimensions. We explore the role of various factors, including the radiative cooling parameter, η = τrad/τcoll (τcoll = Rc/vc), evolutionary modifications on the cloud structure, and the symmetry of the problem. Self-gravity is not included. Radiative losses are taken into account explicitly and not approximated with an isothermal adiabatic index γ ~ 1, which, in fact, leads to very different results. We assume a standard two-phase interstellar medium (ISM) model where clouds are characterized by a temperature Tc = 74 K and number density nc = 22 cm-3 and are in pressure equilibrium with the surrounding warm intercloud medium (WIM), with a density contrast χ = ρc/ρi = 100. In particular, we study collisions for the adiabatic (η >> 1) and radiative (η = 0.38) cases that may correspond to small (Rc <= 0.4 pc for an assumed WIM) or large (Rc ~ 1.5 pc) clouds, respectively. In addition to a standard case of identical ``nonevolved'' clouds, we also consider the collision of identical clouds, ``evolved'' through independent motion within the intercloud gas, over one crushing time before collision. This turns out to be about the mean collision time for such clouds in the ISM. The presence of bow shocks and ram pressure from material in the cloud wake alters these interactions significantly with respect to the standard case. In some cases, we removed the mirror symmetry from the problem by colliding initially identical clouds ``evolved'' to different ages before impact. In those cases, the colliding clouds have different density and velocity structures, so that they provide a first insight on the behavior of more complex interactions. In our adiabatic collisions, the clouds are generally disrupted and convert their gas into the warm phase of the ISM. Although the details

  18. Vector theories in cosmology

    SciTech Connect

    Esposito-Farese, Gilles; Pitrou, Cyril; Uzan, Jean-Philippe

    2010-03-15

    This article provides a general study of the Hamiltonian stability and the hyperbolicity of vector field models involving both a general function of the Faraday tensor and its dual, f(F{sup 2},FF-tilde), as well as a Proca potential for the vector field, V(A{sup 2}). In particular it is demonstrated that theories involving only f(F{sup 2}) do not satisfy the hyperbolicity conditions. It is then shown that in this class of models, the cosmological dynamics always dilutes the vector field. In the case of a nonminimal coupling to gravity, it is established that theories involving Rf(A{sup 2}) or Rf(F{sup 2}) are generically pathologic. To finish, we exhibit a model where the vector field is not diluted during the cosmological evolution, because of a nonminimal vector field-curvature coupling which maintains second-order field equations. The relevance of such models for cosmology is discussed.

  19. Vector generator scan converter

    DOEpatents

    Moore, J.M.; Leighton, J.F.

    1988-02-05

    High printing speeds for graphics data are achieved with a laser printer by transmitting compressed graphics data from a main processor over an I/O channel to a vector generator scan converter which reconstructs a full graphics image for input to the laser printer through a raster data input port. The vector generator scan converter includes a microprocessor with associated microcode memory containing a microcode instruction set, a working memory for storing compressed data, vector generator hardware for drawing a full graphic image from vector parameters calculated by the microprocessor, image buffer memory for storing the reconstructed graphics image and an output scanner for reading the graphics image data and inputting the data to the printer. The vector generator scan converter eliminates the bottleneck created by the I/O channel for transmitting graphics data from the main processor to the laser printer, and increases printer speed up to thirty fold. 7 figs.

  20. Vector generator scan converter

    DOEpatents

    Moore, James M.; Leighton, James F.

    1990-01-01

    High printing speeds for graphics data are achieved with a laser printer by transmitting compressed graphics data from a main processor over an I/O (input/output) channel to a vector generator scan converter which reconstructs a full graphics image for input to the laser printer through a raster data input port. The vector generator scan converter includes a microprocessor with associated microcode memory containing a microcode instruction set, a working memory for storing compressed data, vector generator hardward for drawing a full graphic image from vector parameters calculated by the microprocessor, image buffer memory for storing the reconstructed graphics image and an output scanner for reading the graphics image data and inputting the data to the printer. The vector generator scan converter eliminates the bottleneck created by the I/O channel for transmitting graphics data from the main processor to the laser printer, and increases printer speed up to thirty fold.

  1. SGP and TWP (Manus) Ice Cloud Vertical Velocities

    DOE Data Explorer

    Kalesse, Heike

    2013-06-27

    Daily netcdf-files of ice-cloud dynamics observed at the ARM sites at SGP (Jan1997-Dec2010) and Manus (Jul1999-Dec2010). The files include variables at different time resolution (10s, 20min, 1hr). Profiles of radar reflectivity factor (dbz), Doppler velocity (vel) as well as retrieved vertical air motion (V_air) and reflectivity-weighted particle terminal fall velocity (V_ter) are given at 10s, 20min and 1hr resolution. Retrieved V_air and V_ter follow radar notation, so positive values indicate downward motion. Lower level clouds are removed, however a multi-layer flag is included.

  2. Cloud Arcs in the Western Pacific

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Small cumulus clouds in this natural-color view from the Multi-angle Imaging SpectroRadiometer have formed a distinctive series of quasi-circular arcs. Clues regarding the formation of these arcs can be found by noting that larger clouds exist in the interior of each arc.

    The interior clouds are thicker and likely to be more convectively active than the other clouds, causing much of the air near the centers of the arcs to rise. This air spreads out horizontally in all directions as it rises and continues to spread out as it begins to sink back to the surface. This pushes any existing small cumulus clouds away from the central region of convection.

    As the air sinks, it also warms, preventing other small clouds from forming, so that the regions just inside the arcs are kept clear. At the arcs, the horizontal flow of sinking air is now quite weak and on meeting the undisturbed air it can rise again slightly -- possibly assisting in the formation of new small cumulus clouds. Although examples of the continuity of air, in which every rising air motion must be compensated by a sinking motion elsewhere, are very common, the degree of organization exhibited here is relatively rare, as the wind field at different altitudes usually disrupts such patterns. The degree of self organization of this cloud image, whereby three or four such circular events form a quasi-periodic pattern, probably also requires a relatively uncommon combination of wind, temperature and humidity conditions for it to occur.

    The image was acquired by MISR's nadir camera on March 11, 2002, and is centered west of the Marshall Islands. Enewetak Atoll is discernible through thin cloud as the turquoise band near the right-hand edge of the image.

    The Multi-angle Imaging SpectroRadiometer observes the daylit Earth continuously from pole to pole, and views almost the entire globe every 9 days. This image is a portion of the data acquired during Terra orbit 11863, and covers an area of about 380

  3. Methane Clouds on Titan

    NASA Astrophysics Data System (ADS)

    Griffith, Caitlin A.

    Following the Voyager encounter with Titan in 1981 Saturn's largest moon was hypothesized sport a liquid cycle similar that on Earth with clouds rain and seas. On Titan methane is the condensible playing the role that water plays on Earth. Although the presence of seas is difficult to establish from ground methane clouds have been detected on Titan. Ground-based observations reveal that Titan's clouds differ remarkedly from their terrestrial counterparts. Titan's clouds are sparse reside primarily at particular altitude and concentrate presently in the south pole. That Titan's clouds are exotic is not surprising. Titan receives ~100 times less sunlight than Earth to drive weather. In addition Titan's radiative time constant is 180 years large compared to the 3 month terrestrial value. With little power and sluggish conditions it is not clear how clouds form on Titan. This talk will compare Titan to Earth to explore the nature of clouds under Titan's foreign conditions.

  4. Clouds Over Crater Rim

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Clouds above the rim of 'Endurance Crater' in this image from NASA's Mars Exploration Rover Opportunity can remind the viewer that Mars, our celestial neighbor, is subject to weather. On Earth, clouds like these would be referred to as 'cirrus' or the aptly nicknamed 'mares' tails.' These clouds occur in a region of strong vertical shear. The cloud particles (ice in this martian case) fall out, and get dragged along away from the location where they originally condensed, forming characteristic streamers. Opportunity took this picture with its navigation camera during the rover's 269th martian day (Oct. 26, 2004).

    The mission's atmospheric science team is studying cloud observations to deduce seasonal and time-of-day behavior of the clouds. This helps them gain a better understanding of processes that control cloud formation.

  5. LCD motion blur reduction: a signal processing approach.

    PubMed

    Har-Noy, Shay; Nguyen, Truong Q

    2008-02-01

    Liquid crystal displays (LCDs) have shown great promise in the consumer market for their use as both computer and television displays. Despite their many advantages, the inherent sample-and-hold nature of LCD image formation results in a phenomenon known as motion blur. In this work, we develop a method for motion blur reduction using the Richardson-Lucy deconvolution algorithm in concert with motion vector information from the scene. We further refine our approach by introducing a perceptual significance metric that allows us to weight the amount of processing performed on different regions in the image. In addition, we analyze the role of motion vector errors in the quality of our resulting image. Perceptual tests indicate that our algorithm reduces the amount of perceivable motion blur in LCDs. PMID:18270104

  6. Fast image interpolation for motion estimation using graphics hardware

    NASA Astrophysics Data System (ADS)

    Kelly, Francis; Kokaram, Anil

    2004-05-01

    Motion estimation and compensation is the key to high quality video coding. Block matching motion estimation is used in most video codecs, including MPEG-2, MPEG-4, H.263 and H.26L. Motion estimation is also a key component in the digital restoration of archived video and for post-production and special effects in the movie industry. Sub-pixel accurate motion vectors can improve the quality of the vector field and lead to more efficient video coding. However sub-pixel accuracy requires interpolation of the image data. Image interpolation is a key requirement of many image processing algorithms. Often interpolation can be a bottleneck in these applications, especially in motion estimation due to the large number pixels involved. In this paper we propose using commodity computer graphics hardware for fast image interpolation. We use the full search block matching algorithm to illustrate the problems and limitations of using graphics hardware in this way.

  7. Complex Vector Formalism of Harmonic Oscillator in Geometric Algebra: Particle Mass, Spin and Dynamics in Complex Vector Space

    NASA Astrophysics Data System (ADS)

    Muralidhar, K.

    2014-03-01

    Elementary particles are considered as local oscillators under the influence of zeropoint fields. Such oscillatory behavior of the particles leads to the deviations in their path of motion. The oscillations of the particle in general may be considered as complex rotations in complex vector space. The local particle harmonic oscillator is analyzed in the complex vector formalism considering the algebra of complex vectors. The particle spin is viewed as zeropoint angular momentum represented by a bivector. It has been shown that the particle spin plays an important role in the kinematical intrinsic or local motion of the particle. From the complex vector formalism of harmonic oscillator, for the first time, a relation between mass and bivector spin has been derived in the form . Where, is the angular velocity bivector of complex rotations, is the velocity of light. The unit vector acts as an operator on the idempotents and to give the eigen values The constant represents two fold nature of the equation corresponding to particle and antiparticle states. Further the above relation shows that the mass of the particle may be interpreted as a local spatial complex rotation in the rest frame. This gives an insight into the nature of fundamental particles. When a particle is observed from an arbitrary frame of reference, it has been shown that the spatial complex rotation dictates the relativistic particle motion. The mathematical structure of complex vectors in space and spacetime is developed.

  8. Line Integral of a Vector.

    ERIC Educational Resources Information Center

    Balabanian, Norman

    This programed booklet is designed for the engineering student who understands and can use vector and unit vector notation, components of a vector, parallel law of vector addition, and the dot product of two vectors. Content begins with work done by a force in moving a body a certain distance along some path. For each of the examples and problem…

  9. Diagnosing the severe thunderstorm environment by mesoscale cloud tracking - A new approach and new information

    NASA Technical Reports Server (NTRS)

    Purdom, J. F. W.; Vonder Haar, T. H.; Stewart, J. K.; Leary, N. E.

    1984-01-01

    A new method for cloud tracking and observing storm development using satellite imagery in a cloud relative mode is presented. This method changes the analyst's function to one of monitoring cloud growth and changes over a finite time period and identifying portions of the cloud that are suitable for use as trackers. It is shown how many problems previously encountered by meteorologists in mesoscale cloud tracking can be overcome by using the cloud relative technique to determine mesoscale flow fields whose heights are determined using stereographic techniques. By separating growth and decay from cloud motion in a cumulus field using the method and accurately defining cloud heights, vertical wind shears within mesoscale domains may be defined. When this information is used to study the relative velocity of flows at different levels with respect to a developing or mature storm, improved insight into storm behavior can be achieved.

  10. The physical properties of the interstellar cloud around the heliosphere

    NASA Astrophysics Data System (ADS)

    Gry, C.

    2015-12-01

    A new interpretation of interstellar absorption lines in the spectra of nearby stars indicates that the medium surrounding the Sun can be regarded as a single, coherent cloud if we relax the assumption that a cloud behaves like a rigid body. This outlook permits us to construct a comprehensive picture of the local interstellar cloud and reveals that it departs from homogeneity in a number of aspects and physical properties: - This local cloud undergoes a deformation related to a compression in the direction of motion and an expansion in perpendicular directions, much like a squashed balloon. - The metal abundances decrease steadily from the rear to the head of the cloud, and this phenomenon does not appear to be related to ionization effects. - The cloud average HI density, estimated toward a number of nearby stars around which an astrophere is detected in Lyman alpha, varies from 0.03 to 0.1 cm-3. The cloud outer boundary inferred from the average density and column densities is very irregular with an average distance to the Sun of 9 +/- 7 pc. - The electron density and the cloud temperature can be derived from the combination of the ionization equilibrium of MgI and the excitation of CII in a restricted number of sightlines where column density is such that MgI and CII* features are strong enough to be detectable without saturating MgII. We present a few additional targets from which we examine the physical conditions inside the cloud.

  11. On the stability and causality of scalar-vector theories

    SciTech Connect

    Fleury, Pierre; Pitrou, Cyril; Uzan, Jean-Philippe; Almeida, Juan P. Beltrán E-mail: juanpbeltran@uan.edu.co E-mail: uzan@iap.fr

    2014-11-01

    Various extensions of standard inflationary models have been proposed recently by adding vector fields. Because they are generally motivated by large-scale anomalies, and the possibility of statistical anisotropy of primordial fluctuations, such models require to introduce non-standard couplings between vector fields on the one hand, and either gravity or scalar fields on the other hand. In this article, we study models involving a vector field coupled to a scalar field. We derive restrictive necessary conditions for these models to be both stable (Hamiltonian bounded by below) and causal (hyperbolic equations of motion)

  12. Rotational motion of Foton M-4

    NASA Astrophysics Data System (ADS)

    Abrashkin, V. I.; Voronov, K. E.; Piyakov, I. V.; Puzin, Yu. Ya.; Sazonov, V. V.; Semkin, N. D.; Chebukov, S. Yu.

    2016-07-01

    The actual controlled rotational motion of the Foton M-4 satellite is reconstructed for the mode of single-axis solar orientation. The reconstruction was carried out using data of onboard measurements of vectors of angular velocity and the strength of the Earth's magnetic field. The reconstruction method is based on the reconstruction of the kinematic equations of the rotational motion of a solid body. According to the method, measurement data of both types collected at a certain time interval are processed together. Measurements of the angular velocity are interpolated by piecewise-linear functions, which are substituted in kinematic differential equations for a quaternion that defines the transition from the satellite instrument coordinate system to the inertial coordinate system. The obtained equations represent the kinematic model of the satellite rotational motion. A solution of these equations that approximates the actual motion is derived from the condition of the best (in the sense of the least squares method) match between the measurement data of the strength vector of the Earth's magnetic field and its calculated values. The described method makes it possible to reconstruct the actual rotational satellite motion using one solution of kinematic equations over time intervals longer than 10 h. The found reconstructions have been used to calculate the residual microaccelerations.

  13. Speed tuning of motion segmentation and discrimination

    NASA Technical Reports Server (NTRS)

    Masson, G. S.; Mestre, D. R.; Stone, L. S.

    1999-01-01

    Motion transparency requires that the visual system distinguish different motion vectors and selectively integrate similar motion vectors over space into the perception of multiple surfaces moving through or over each other. Using large-field (7 degrees x 7 degrees) displays containing two populations of random-dots moving in the same (horizontal) direction but at different speeds, we examined speed-based segmentation by measuring the speed difference above which observers can perceive two moving surfaces. We systematically investigated this 'speed-segmentation' threshold as a function of speed and stimulus duration, and found that it increases sharply for speeds above approximately 8 degrees/s. In addition, speed-segmentation thresholds decrease with stimulus duration out to approximately 200 ms. In contrast, under matched conditions, speed-discrimination thresholds stay low at least out to 16 degrees/s and decrease with increasing stimulus duration at a faster rate than for speed segmentation. Thus, motion segmentation and motion discrimination exhibit different speed selectivity and different temporal integration characteristics. Results are discussed in terms of the speed preferences of different neuronal populations within the primate visual cortex.

  14. Stellar streams around the Magellanic Clouds

    NASA Astrophysics Data System (ADS)

    Belokurov, Vasily; Koposov, Sergey E.

    2016-02-01

    Using blue horizontal branch (BHB) stars identified in the Dark Energy Survey (DES) Year 1 data, we report the detection of an extended and lumpy stellar debris distribution around the Magellanic Clouds. At the heliocentric distance of the Clouds, overdensities of BHBs are seen to reach at least to ˜30°, and perhaps as far as ˜50° from the Large Magellanic Cloud (LMC). In 3D, the stellar halo is traceable to between 25 and 50 kpc from the LMC. We catalogue the most significant of the stellar substructures revealed, and announce the discovery of a number of narrow streams and diffuse debris clouds. Two narrow streams appear approximately aligned with the Magellanic Clouds' proper motion. Moreover, one of these overlaps with the gaseous Magellanic Stream on the sky. Curiously, two diffuse BHB agglomerations seem coincident with several of the recently discovered DES satellites. Given the enormous size and the conspicuous lumpiness of the LMC's stellar halo, we speculate that the dwarf could easily have been more massive than previously had been assumed.

  15. Movie of High Clouds on Jupiter

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Jupiter's high-altitude clouds are seen in this brief movie made from seven frames taken by the narrow-angle camera of NASA's Cassini spacecraft. This is the first time a movie sequence of Jupiter has been made that illustrates the motions of the high-altitude clouds on a global scale.

    The images were taken at a wavelength that is absorbed by methane, one chemical in Jupiter's lower clouds. So, dark areas are relatively free of high clouds, and the camera sees through to the methane in a lower level. Bright areas are places with high, thick clouds that shield the methane below.

    Jupiter's equator and Great Red Spot are covered with high-altitude, hazy clouds.

    The movie covers the time period between Oct. 1 and Oct. 5, 2000, latitudes from 50 degrees north to 50 degrees south, and a 100-degree sweep of longitude. Those factors were the same for a Cassini movie of cloud motions previously released (PIA02829), but that movie used frames taken through a blue filter, which showed deeper cloud levels and sharper detail. Features in this methane-filter movie appear more diffuse.

    Among the nearly stationary features are the Red Spot and some bright ovals at mid-latitudes in both hemispheres. These are anticyclonic (counter-clockwise rotating) storms. They are bright in the methane band because of their high clouds associated with rising gas. They behave differently from terrestrial cyclones, which swirl in the opposite direction. The mechanism making the Red Spot and similar spots stable apparently has no similarity to the mechanism which feeds terrestrial cyclones.

    Some small-scale features are fascinating because of their brightness fluctuations. Such fluctuations observed in the methane band are probably caused by strong vertical motions, which form clouds rapidly, as in Earth's thunderstorms. Near the upper left corner in this movie, a number of smaller clouds appear to circulate counterclockwise around a dark spot, and these clouds fluctuate in

  16. Fractal vector optical fields.

    PubMed

    Pan, Yue; Gao, Xu-Zhen; Cai, Meng-Qiang; Zhang, Guan-Lin; Li, Yongnan; Tu, Chenghou; Wang, Hui-Tian

    2016-07-15

    We introduce the concept of a fractal, which provides an alternative approach for flexibly engineering the optical fields and their focal fields. We propose, design, and create a new family of optical fields-fractal vector optical fields, which build a bridge between the fractal and vector optical fields. The fractal vector optical fields have polarization states exhibiting fractal geometry, and may also involve the phase and/or amplitude simultaneously. The results reveal that the focal fields exhibit self-similarity, and the hierarchy of the fractal has the "weeding" role. The fractal can be used to engineer the focal field. PMID:27420485

  17. Silicon photonics cloud (SiCloud)

    NASA Astrophysics Data System (ADS)

    DeVore, Peter T. S.; Jiang, Yunshan; Lynch, Michael; Miyatake, Taira; Carmona, Christopher; Chan, Andrew C.; Muniam, Kuhan; Jalali, Bahram

    2015-02-01

    We present SiCloud (Silicon Photonics Cloud), the first free, instructional web-based research and education tool for silicon photonics. SiCloud's vision is to provide a host of instructional and research web-based tools. Such interactive learning tools enhance traditional teaching methods by extending access to a very large audience, resulting in very high impact. Interactive tools engage the brain in a way different from merely reading, and so enhance and reinforce the learning experience. Understanding silicon photonics is challenging as the topic involves a wide range of disciplines, including material science, semiconductor physics, electronics and waveguide optics. This web-based calculator is an interactive analysis tool for optical properties of silicon and related material (SiO2, Si3N4, Al2O3, etc.). It is designed to be a one stop resource for students, researchers and design engineers. The first and most basic aspect of Silicon Photonics is the Material Parameters, which provides the foundation for the Device, Sub-System and System levels. SiCloud includes the common dielectrics and semiconductors for waveguide core, cladding, and photodetection, as well as metals for electrical contacts. SiCloud is a work in progress and its capability is being expanded. SiCloud is being developed at UCLA with funding from the National Science Foundation's Center for Integrated Access Networks (CIAN) Engineering Research Center.

  18. Automated cloud tracking using precisely aligned digital ATS pictures.

    NASA Technical Reports Server (NTRS)

    Smith, E. A.; Phillips, D. R.

    1971-01-01

    An interactive man-computer system, termed WINDCO, which was developed to measure cloud motions from pictures obtained by the ATS-I and ATS-III satellites, is described. The system will measure motions to at least three knots at moderate cost in a real-time environment. Accuracy could be improved by a factor of 4 by incorporating high-resolution visible SMS data.

  19. A Hierarchical Modeling Study of the Interactions Among Turbulence, Cloud Microphysics, and Radiative Transfer in the Evolution of Cirrus Clouds

    NASA Technical Reports Server (NTRS)

    Curry, Judith; Khvorostyanov, V. I.

    2005-01-01

    This project used a hierarchy of cloud resolving models to address the following science issues of relevance to CRYSTAL-FACE: What ice crystal nucleation mechanisms are active in the different types of cirrus clouds in the Florida area and how do these different nucleation processes influence the evolution of the cloud system and the upper tropospheric humidity? How does the feedback between supersaturation and nucleation impact the evolution of the cloud? What is the relative importance of the large-scale vertical motion and the turbulent motions in the evolution of the crystal size spectra? How does the size spectra impact the life-cycle of the cloud, stratospheric dehydration, and cloud radiative forcing? What is the nature of the turbulence and waves in the upper troposphere generated by precipitating deep convective cloud systems? How do cirrus microphysical and optical properties vary with the small-scale dynamics? How do turbulence and waves in the upper troposphere influence the cross-tropopause mixing and stratospheric and upper tropospheric humidity? The models used in this study were: 2-D hydrostatic model with explicit microphysics that can account for 30 size bins for both the droplet and crystal size spectra. Notably, a new ice crystal nucleation scheme has been incorporated into the model. Parcel model with explicit microphysics, for developing and evaluating microphysical parameterizations. Single column model for testing bulk microphysics parameterizations

  20. Electron Cloud Effect in the Linear Colliders

    SciTech Connect

    Pivi, M

    2004-09-13

    Beam induced multipacting, driven by the electric field of successive positively charged bunches, may arise from a resonant motion of electrons, generated by secondary emission, bouncing back and forth between opposite walls of the vacuum chamber. The electron-cloud effect (ECE) has been observed or is expected at many storage rings [1]. In the beam pipe of the Damping Ring (DR) of a linear collider, an electron cloud is produced initially by ionization of the residual gas and photoelectrons from the synchrotron radiation. The cloud is then sustained by secondary electron emission. This electron cloud can reach equilibrium after the passage of only a few bunches. The electron-cloud effect may be responsible for collective effects as fast coupled-bunch and single-bunch instability, emittance blow-up or incoherent tune shift when the bunch current exceeds a certain threshold, accompanied by a large number of electrons in the vacuum chamber. The ECE was identified as one of the most important R&D topics in the International Linear Collider Report [2]. Systematic studies on the possible electron-cloud effect have been initiated at SLAC for the GLC/NLC and TESLA linear colliders, with particular attention to the effect in the positron main damping ring (MDR) and the positron Low Emittance Transport which includes the bunch compressor system (BCS), the main linac, and the beam delivery system (BDS). We present recent computer simulation results for the main features of the electron cloud generation in both machine designs. Thus, single and coupled-bunch instability thresholds are estimated for the GLC/NLC design.

  1. Polarization vision in crayfish motion detectors.

    PubMed

    Glantz, Raymon M

    2008-06-01

    Motion detector interneurons were examined to determine their responsiveness to the motion of polarized light images (i.e. images segmented by spatial variations in e-vector angle). Computer generated images were displayed as intensity contrasts or polarization contrasts on a modified LCD projection panel. The stimuli included the motion of a single stripe (45 degrees -55 degrees /s) and the global motion of a square wave grating (3.3 degrees /s). Neurons were impaled in the medulla interna. Of the neurons which exhibited a directional response to the motion of intensity contrast stimuli, about 2/3 were also directional in the response to polarized light images. Transient (nondirectional) stimuli included looming and jittery motions. The responses to the transient motions of the polarized light images were roughly comparable to those elicited by intensity contrast. The results imply that behavioral responses to polarized light images (i.e. optokinetic and defense reflexes) may have a basis in the polarization sensitivity and synaptic organization of the medulla interna. PMID:18386016

  2. Interpretation of MODIS Cloud Images by CloudSat/CALIPSO Cloud Vertical Profiles

    NASA Astrophysics Data System (ADS)

    Wang, T.; Fetzer, E. J.; Wong, S.; Yue, Q.

    2015-12-01

    Clouds observed by passive remote-sensing imager (Aqua-MODIS) are collocated to cloud vertical profiles observed by active profiling sensors (CloudSat radar and CALIPSO lidar) at the pixel-scale. By comparing different layers of cloud types classified in the 2B-CLDCLASS-LIDAR product from CloudSat+CALIPSO to those cloud properties observed by MODIS, we evaluate the occurrence frequencies of cloud types and cloud-overlap in CloudSat+CALIPSO for each MODIS cloud regime defined by cloud optical depth (τ) and cloud-top pressure (P) histograms. We find that about 70% of MODIS clear sky agrees with the clear category in CloudSat+CALIPSO; whereas the remainder is either single layer (~25%) cirrus (Ci), low-level cumulus (Cu), stratocumulus (Sc), or multi-layer (<5%) clouds in CloudSat+CALIPSO. Under MODIS cloudy conditions, 60%, 28%, and 8% of the occurrences show single-, double-, and triple-layer clouds, respectively in CloudSat+CALIPSO. When MODIS identifies single-layer clouds, 50-60% of the MODIS low-level clouds are categorized as stratus (Sc) in CloudSat+CALIPSO. Over the tropics, ~70% of MODIS high and optically thin clouds (considered as cirrus in the histogram) is also identified as Ci in CloudSat+CALIPSO, and ~40% of MODIS high and optically thick clouds (considered as convective in the histogram) agrees with CloudSat+CALIPSO deep convections (DC). Over mid-latitudes these numbers drop to 45% and 10%, respectively. The best agreement occurs in tropical single-layer cloud regimes, where 90% of MODIS high-thin clouds are identified as Ci by CloudSat+CALIPSO and 60% of MODIS high-thick clouds are identified as DC. Worst agreement is found for multi-layer clouds, where cirrus on top of low- and mid-level clouds in MODIS are frequently categorized as high-thick clouds by passive imaging - among these only 5-12% are DC in CloudSat+CALIPSO. It is encouraging that both MODIS low-level clouds (regardless of optical thickness) and high-level thin clouds are consistently

  3. Labyrinthine lesions and motion sickness susceptibility

    PubMed Central

    Raphan, Theodore; Cohen, Bernard

    2011-01-01

    The angular vestibulo-ocular reflex (aVOR) has a fast pathway, which mediates compensatory eye movements, and a slow (velocity storage) pathway, which determines its low frequency characteristics and orients eye velocity toward gravity. We have proposed that motion sickness is generated through velocity storage, when its orientation vector, which lies close to the gravitational vertical, is misaligned with eye velocity during head motion. The duration of the misalignment, determined by the dominant time constant of velocity storage, causes the buildup of motion sickness. To test this hypothesis, we studied bilateral labyrinthine-defective subjects with short vestibular time constants but normal aVOR gains for their motion sickness susceptibility. Time constants and gains were taken from rotational responses. Motion sickness was generated by rolling the head while rotating, and susceptibility was assessed by the number of head movements made before reaching intolerable levels of nausea. More head movements signified lower motion sickness susceptibility. Labyrinthine-defective subjects made more head movements on their first exposure to roll while rotating than normals (39.8 ± 7.2 vs 13.7 ± 5.5; P < 0.0001). Normals were tested eight times, which habituated their time constants and reduced their motion sickness susceptibility. Combining data from all subjects, there was a strong inverse relationship between time constants and number of head movements (r = 0.94), but none between motion sickness susceptibility and aVOR gains. This provides further evidence that motion sickness is generated through velocity storage, not the direct pathway, and suggests that motion sickness susceptibility can be reduced by reducing the aVOR time constant. PMID:17256169

  4. Mab's orbital motion explained

    NASA Astrophysics Data System (ADS)

    Kumar, K.; de Pater, I.; Showalter, M. R.

    2015-07-01

    We explored the hypothesis that Mab's anomalous orbital motion, as deduced from Hubble Space Telescope (HST) data (Showalter, M.R., Lissauer, J.J. [2006]. Science (New York, NY) 311, 973-977), is the result of gravitational interactions with a putative suite of large bodies in the μ-ring. We conducted simulations to compute the gravitational effect of Mab (a recently discovered Uranian moon) on a cloud of test particles. Subsequently, by employing the data extracted from the test particle simulations, we executed random walk simulations to compute the back-reaction of nearby perturbers on Mab. By generating simulated observation metrics, we compared our results to the data retrieved from the HST. Our results indicate that the longitude residual change noted in the HST data (Δλr,Mab ≈ 1 deg) is well matched by our simulations. The eccentricity variations (ΔeMab ≈10-3) are however typically two orders of magnitude too small. We present a variety of reasons that could account for this discrepancy. The nominal scenario that we investigated assumes a perturber ring mass (mring) of 1 mMab (Mab's mass) and a perturber ring number density (ρn,ring) of 10 perturbers per 3 RHill,Mab (Mab's Hill radius). This effectively translates to a few tens of perturbers with radii of approximately 2-3 km, depending on the albedo assumed. The results obtained also include an interesting litmus test: variations of Mab's inclination on the order of the eccentricity changes should be observable. Our work provides clues for further investigation into the tantalizing prospect that the Mab/μ-ring system is undergoing re-accretion after a recent catastrophic disruption.

  5. What is a Cloud?

    NASA Astrophysics Data System (ADS)

    Long, C. N.; Wu, W.

    2013-12-01

    There are multiple factors that cause disagreements between differing methods using differing instruments to infer cloud amounts. But along with these issues is a fundamental concern that has permeated all comparisons and supersedes such questions as what are the uncertainty estimates of a given retrieval. To wit: what is a cloud? How can uncertainty of a cloud amount measurement be determined when there is no absolute 'truth' on what defines a cloud, as opposed to cloud-free? Recent research comparing a decade of surface- and satellite-based retrievals of cloud amount for the ARM Southern Great Plains site shows significant disagreements. While Total Sky Imager 100-degree FOV, Shortwave (SW) Radiative Flux Analysis, GOES satellite and PATMOS-x satellite amounts agree relatively well, ISCCP satellite and ARSCL time-series cloud amounts are significantly greater, 15% (ISCCP) and 8% (ARSCL) larger in average diurnal variations. In both cases, it appears that optically thin high ice is counted as 'cloud' in ARSCL and ISCCP that is not categorized as cloud by all the others. Additionally, cloud amounts from three methods (ISCCP, ARSCL, and GOES) show an overall increase of 8%-10% in the annually averaged cloud fractions from 1998 to 2009, while those from the other three (TSI, SWFA, PATMOS-x) show little trend for this period. So one wonders: are cloud amounts increasing or not over this period? The SW Flux Analysis used sky imager retrievals as 'truth' in development of the methodology (Long et al, 2006a), where sky imagery itself used human observations as the model (Long et al., 2006b). Min et al. (2008) then used SW Flux Analysis retrievals as 'truth' to develop an MFRSR-based spectral SW retrieval method. Dupont et al. (2008) show that the SW-based retrievals allow up to a visible optical depth of 0.15 (95% of occurrences) under the 'clear-sky' category which primarily consists of sub-visual cirrus, which by ancestry applies to spectral SW, sky imager and human

  6. Stratus Cloud Supersaturations

    NASA Astrophysics Data System (ADS)

    Noble, S.; Hudson, J. G.; Jha, V.

    2009-12-01

    Extensive aircraft measurements of cloud microphysics and complete CCN spectra from 15 flights in central California stratus clouds are presented. Cloud droplet and CCN concentrations varied over an order of magnitude in this July-August, 2008 POST project. Correlation coefficients (R) between CCN and average total cloud droplet concentrations within parcels with specific minimal liquid water contents (LWC) are shown in the table. For most LWC thresholds R is greatest for CCN concentrations at rather high supersaturations (S); i.e., 1%. The highest R for the 0.1 gm-3 are for the 300’ altitude CCN measurements but the number of cases is very small. The 0.5 g-3 R values are higher at lower S but the number of cases is also very small. The high cloud S implied by most R values goes against conventional wisdom that low stratus cloud updraft velocities limit cloud S to < 0.3%. On the other hand average droplet concentrations for most LWC thresholds match best the CCN concentrations at 0.2-0.3% S, which is more in keeping with conventional wisdom. However, these average droplet concentrations were probably reduced from adiabatic values by entrainment, which would suggest higher initial cloud S. Yum and Hudson (2002, Tellus) did report S > 1% in some maritime clouds. Further research is ongoing with this data set to substantiate stratus cloud S values. If stratus cloud S is determined to be higher than previous estimates this would imply that a much larger subset of particles (even smaller sizes) influence cloud microphysics and this would have important climate implications. As has recently been reported for small cumulus clouds (Hudson et al. 2009 JGR and Hudson and Noble 2009 GRL) negative R values were found for CCN with larger cloud droplets and drizzle drop concentrations. Correlation coefficients (R) between average droplet and CCN concentrations. 1st row (1 min)is for CCN measurements in ascents or descents closest to cloud base. 2nd row is for CCN averaged in

  7. multi-dimensional Cloud-aERosol Exploratory Study using RPAS (mCERES): Bottom-up and top-down closure of aerosol-cloud interactions

    NASA Astrophysics Data System (ADS)

    Roberts, Greg; Calmer, Radiance; Sanchez, Kevin; Cayez, Grégoire; Nicoll, Kerianne; Hashimshoni, Eyal; Rosenfeld, Daniel; Ansmann, Albert; Sciare, Jean; Ovadneite, Jurgita; Bronz, Murat; Hattenberger, Gautier; Preissler, Jana; Buehl, Johannes; Ceburnis, Darius; O'Dowd, Colin

    2016-04-01

    Clouds are omnipresent in earth's atmosphere and constitute an important role in regulating the radiative budget of the planet. However, the response of clouds to climate change remains uncertain, in particular, with respect to aerosol-cloud interactions and feedback mechanisms between the biosphere and atmosphere. Aerosol-cloud interactions and their feedbacks are the main themes of the European project FP7 BACCHUS (Impact of Biogenic versus Anthropogenic Emissions on Clouds and Climate: towards a Holistic Understanding). The National Center for Meteorological Research (CNRM-GAME, Toulouse, France) conducted airborne experiments in Cyprus and Ireland in March and August 2015 respectively to link ground-based and satellite observations. Multiple RPAS (remotely piloted aircraft systems) were instrumented for a specific scientific focus to characterize the vertical distribution of aerosol, cloud microphysical properties, radiative fluxes, 3D wind vectors and meteorological state parameters. Flights below and within clouds were coordinated with satellite overpasses to perform 'top-down' closure of cloud micro-physical properties. Measurements of cloud condensation nuclei spectra at the ground-based site have been used to determine cloud microphyical properties using wind vectors and meteorological parameters measured by the RPAS at cloud base. These derived cloud properties have been validated by in-situ RPAS measurements in the cloud and compared to those derived by the Suomi-NPP satellite. In addition, RPAS profiles in Cyprus observed the layers of dust originating from the Arabian Peninsula and the Sahara Desert. These profiles generally show a well-mixed boundary layer and compare well with ground-based LIDAR observations.

  8. Understanding Vector Fields.

    ERIC Educational Resources Information Center

    Curjel, C. R.

    1990-01-01

    Presented are activities that help students understand the idea of a vector field. Included are definitions, flow lines, tangential and normal components along curves, flux and work, field conservation, and differential equations. (KR)

  9. Bunch of restless vector solitons in a fiber laser with SESAM.

    PubMed

    Zhao, L M; Tang, D Y; Zhang, H; Wu, X

    2009-05-11

    We report on the experimental observation of a novel form of vector soliton interaction in a fiber laser mode-locked with SESAM. Several vector solitons bunch in the cavity and move as a unit with the cavity repetition rate. However, inside the bunch the vector solitons make repeatedly contractive and repulsive motions, resembling the contraction and extension of a spring. The number of vector solitons in the bunch is controllable by changing the pump power. In addition, polarization rotation locking and period doubling bifurcation of the vector soliton bunch are also experimentally observed. PMID:19434141

  10. Energy Aware Clouds

    NASA Astrophysics Data System (ADS)

    Orgerie, Anne-Cécile; de Assunção, Marcos Dias; Lefèvre, Laurent

    Cloud infrastructures are increasingly becoming essential components for providing Internet services. By benefiting from economies of scale, Clouds can efficiently manage and offer a virtually unlimited number of resources and can minimize the costs incurred by organizations when providing Internet services. However, as Cloud providers often rely on large data centres to sustain their business and offer the resources that users need, the energy consumed by Cloud infrastructures has become a key environmental and economical concern. This chapter presents an overview of techniques that can improve the energy efficiency of Cloud infrastructures. We propose a framework termed as Green Open Cloud, which uses energy efficient solutions for virtualized environments; the framework is validated on a reference scenario.

  11. Inhomogeneous cirrus clouds during the AIRTOSS campaign

    NASA Astrophysics Data System (ADS)

    Voigt, Matthias; Spichtinger, Peter

    2015-04-01

    The aircraft campaign AIRTOSS-ICE in May and September 2013 provided measurement data of cirrus clouds over North Sea and Baltic Sea in various meteorological situations. The measurements were carried out with a Learjet and a towed sensor shuttle below the aircraft [2]. This configuration allows us to obtain almost horizontally collocated measurements at different vertical levels (inside and outside clouds). Microphysical properties of cirrus clouds, as ice water content, ice crystal number concentrations, diameter and shape of ice crystals were measured. In this study we concentrate on the comparison of in situ measurements with model simulations. For these case studies, the issue about the main formation mechanism (homogeneous vs. heterogeneous or both) will be addressed. In a first step the meteorological conditions leading to the cirrus formation are analyzed using meteorological analyses as obtained from the European Centre for Medium-Range Forecasts (ECMWF). The ECMWF wind fields are then used to calculate backward trajectories with the Lagrangian analysis tool LAGRANTO [4]. From these investigations the large-scale/mesoscale motions are derived and analyzed. Finally, the meteorological analyses and measurements (temperature, wind, humidity) are used as initial conditions for cirrus cloud simulations where the small scale motions are derived and analyzed. We used EULAG as LES model, including a state-of-the-art ice microphysics scheme [3] for 2D and 3D idealized and quasi-realistic simulations. In order to address the impact of dynamics vs. microphysics (i.e. heterogeneous nucleation [1]), we investigated different environmental conditions. The microphysical and macrophysical properties of the simulated cloud are finally compared to the measurements, in order to get some information about the most probable scenarios. References [1] D. J. Cziczo, K. D. Froyd, C. Hoose, E. J. Jensen, M. H. Diao, M. A. Zondlo, J. B. Smith, C. H. Twohy, and D. M. Murphy

  12. Impact of the ice phase on a mesoscale convective system: Implication of cloud parameterization and cloud radiative properties

    SciTech Connect

    Chin, H.N.S.; Bradley, M.M.; Molenkamp, C.R.; Grant, K.E.; Chuang, C.

    1991-08-01

    This study attempts to provide further understanding of the effect of the ice phase on cloud ensemble features which are useful for improving GCM cumulus parameterization. In addition, cloud model results are used to diagnose the radiative properties of anvils in order to assess cloud/radiation interaction and its feedback on the larger-scale climate for the future work. The heat, moisture and mass budget analyses of a simulated squall line system indicate that, at least for this type of system, the inclusion of the ice phase in the microphysics does not considerably change the net cloud heating and drying effects and the feedback on the large-scale motion. Nonetheless, its impact on the radiative properties of clouds significantly influences not only the squall line system itself, but also the larger-scale circulation due to the favorable stratification for long-lasting anvil clouds. The water budget suggests a simple methodology to parameterize the microphysical effect without considering it as a model physics module. Further application of the water budget might also be used to parameterize the cloud transport of condensates in the anvil cloud region, which allows the GCM columns to interact with each other. The findings of this study suggest that the ice phase could be ignored in the cloud parameterization in order to save significant amounts of computational resources and to simplify the model physics. More scientific effort should, however, be focused on the effect of the ice phase to further explore cloud feedback on the large-scale climate through the radiative process. The cloud/radiation interaction and its feedback on the larger-scale climate will be addressed in a companion study by coupling the radiative transfer model with the cloud model. 19 refs., 13 figs.

  13. Bloch vector projection noise

    NASA Technical Reports Server (NTRS)

    Wang, Li-Jun; Bacon, A. M.; Zhao, H.-Z.; Thomas, J. E.

    1994-01-01

    In the optical measurement of the Bloch vector components describing a system of N two-level atoms, the quantum fluctuations in these components are coupled into the measuring optical field. This paper develops the quantum theory of optical measurement of Bloch vector projection noise. The preparation and probing of coherence in an effective two-level system consisting of the two ground states in an atomic three-level lambda-scheme are analyzed.

  14. Poynting-vector filter

    SciTech Connect

    Carrigan, Charles R.

    2011-08-02

    A determination is made of frequency components associated with a particular bearing or location resulting from sources emitting electromagnetic-wave energy for which a Poynting-Vector can be defined. The broadband frequency components associated with a specific direction or location of interest are isolated from other components in the power spectrum that are not associated with the direction or location of interest. The collection of pointing vectors can be used to characterize the source.

  15. Low-cost multi-hypothesis motion compensation for video coding

    NASA Astrophysics Data System (ADS)

    Chen, Lei; Dong, Shengfu; Wang, Ronggang; Wang, Zhenyu; Ma, Siwei; Wang, Wenmin; Gao, Wen

    2014-02-01

    In conventional motion compensation, prediction block is related only with one motion vector for P frame. Multihypothesis motion compensation (MHMC) is proposed to improve the prediction performance of conventional motion compensation. However, multiple motion vectors have to be searched and coded for MHMC. In this paper, we propose a new low-cost multi-hypothesis motion compensation (LMHMC) scheme. In LMHMC, a block can be predicted from multiple-hypothesis with only one motion vector to be searched and coded into bit-stream, other motion vectors are predicted from motion vectors of neighboring blocks, and so both the encoding complexity and bit-rate of MHMC can be saved by our proposed LMHMC. By adding LMHMC as an additional mode in MPEG internet video coding (IVC) platform, the B-D rate saving is up to 10%, and the average B-D rate saving is close to 5% in Low Delay configure. We also compare the performance between MHMC and LMHMC in IVC platform, the performance of MHMC is improved about 2% on average by LMHMC.

  16. Ammonia Clouds on Jupiter

    NASA Technical Reports Server (NTRS)

    2007-01-01

    [figure removed for brevity, see original site] Click on the image for movie of Ammonia Ice Clouds on Jupiter

    In this movie, put together from false-color images taken by the New Horizons Ralph instrument as the spacecraft flew past Jupiter in early 2007, show ammonia clouds (appearing as bright blue areas) as they form and disperse over five successive Jupiter 'days.' Scientists noted how the larger cloud travels along with a small, local deep hole.

  17. A motion picture presentation of magnetic pulsations

    NASA Technical Reports Server (NTRS)

    Suzuki, A.; Kim, J. S.; Sugura, M.; Nagano, H.

    1981-01-01

    Using the data obtained from the IMS North American magnetometer network stations at high latitudes, a motion picture was made by a computer technique, describing time changes of Pc5 and Pi3 magnetic pulsation vectors. Examples of pulsation characteristics derived from this presentation are regional polarization changes including shifts of polarization demarcation lines, changes in the extent of an active region and its movement with time.

  18. Short-Range Structure of Clouds Studied by High Resolution Photography From the Surface

    NASA Astrophysics Data System (ADS)

    Schwartz, S. E.; Huang, D.; Vladutescu, D. V.

    2015-12-01

    Clouds exhibit structures at a wide range of length scales. Passive radiometry from satellite shows structure on scales of tens to thousands of kilometers, but there is much structure at short spatial scales not resolved by satellite imagery. Here we use a commercial camera having high spatial resolution (~20 μrad) and high dynamic range (16 bits in each of three color channels) in narrow field-of-view (20 mrad, 110 mrad), zenith-looking mode from the surface, to examine clouds at the scale of centimeters to a few hundred meters, focusing on non-precipitating single-layer clouds during daytime. Up-looking photography of clouds from the surface affords the further advantage, relative to satellite imagery, of black background (space) with contributions to radiance only from blue sky (Rayleigh scattering), aerosols, and clouds, permitting reconstruction of observed radiance by radiation transfer modeling. Contrast between cloudy and cloud-free sky is enhanced in Red/(Red + Blue), RRB, image Figure 1, but no unique value of RRB distinguishes a pixel as cloud vs. cloud-free. Short-range variability is characterized by the autocorrelation length scale, which is not uncommonly as short as a few meters; longer range variability, such as cloud characteristic size, separation distance, and cloud spatial organization, is also characterized. Scene reconstruction yields the 2D distribution of cloud optical depth; spatial inhomogeneity is attributed mainly to horizontal variation in vertical motion of the air and resultant condensation or evaporation associated with upward or downward motion, respectively. Alternative approaches to calculation of the radiative influence of such clouds from the autocorrelation structure of the cloud field are examined. Figure 1. RGB image of zenith sky at New York City, May 22, 2015, (field of view 21 mrad corresponding to 56 m at cloud altitude 2.6 km) showing broken single-layer cloud; corresponding RRB image; and autocorrelation of RRB image.

  19. Demonstrating the Direction of Angular Velocity in Circular Motion

    NASA Astrophysics Data System (ADS)

    Demircioglu, Salih; Yurumezoglu, Kemal; Isik, Hakan

    2015-09-01

    Rotational motion is ubiquitous in nature, from astronomical systems to household devices in everyday life to elementary models of atoms. Unlike the tangential velocity vector that represents the instantaneous linear velocity (magnitude and direction), an angular velocity vector is conceptually more challenging for students to grasp. In physics classrooms, the direction of an angular velocity vector is taught by the right-hand rule, a mnemonic tool intended to aid memory. A setup constructed for instructional purposes may provide students with a more easily understood and concrete method to observe the direction of the angular velocity. This article attempts to demonstrate the angular velocity vector using the observable motion of a screw mounted to a remotely operated toy car.

  20. Acoustic vector fields in underwater waveguides

    NASA Astrophysics Data System (ADS)

    Rapids, Brian

    2005-09-01

    The ability to compute the sound pressure level as well as the vectors associated with the acoustic particle motion has existed for some time. However, propagation studies and ambient noise investigations have typically focused only upon the sound pressure levels that would be observed by an omnidirectional hydrophone or array of hydrophones. Recent interest in geophones and accelerometers for use as vector and dyadic sensors should encourage the investigation and analysis of the underlying vector fields contributing to the acoustic intensity and energy density fields. The frequency domain properties of the acoustic vector field generated by monopole sources having frequencies <1kHz in a simple iso-velocity waveguide are presented in order to build a fundamental understanding of the related quantities. Subsequently, similar field quantities computed for more realistic environments such as downward refracting profiles and deep-water profiles supporting convergence zone propagation will be discussed. Regions and phenomena associated with perturbations in the energy flux density will be highlighted.

  1. Scanning Cloud Radar Observations at the ARM sites

    NASA Astrophysics Data System (ADS)

    Kollias, P.; Clothiaux, E. E.; Shupe, M.; Widener, K.; Bharadwaj, N.; Miller, M. A.; Verlinde, H.; Luke, E. P.; Johnson, K. L.; Jo, I.; Tatarevic, A.; Lamer, K.

    2012-12-01

    Recently, the DOE Atmospheric Radiation Measurement (ARM) program upgraded its fixed and mobile facilities with the acquisition of state-of-the-art scanning, dual-wavelength, polarimetric, Doppler cloud radars. The scanning ARM cloud radars (SACR's) are the most expensive and significant radar systems at all ARM sites and eight SACR systems will be operational at ARM sites by the end of 2013. The SACR's are the primary instruments for the detection of 3D cloud properties (boundaries, volume cloud fractional coverage, liquid water content, dynamics, etc.) beyond the soda-straw (profiling) limited view. Having scanning capabilities with two frequencies and polarization allows more accurate probing of a variety of cloud systems (e.g., drizzle and shallow, warm rain), better correction for attenuation, use of attenuation for liquid water content retrievals, and polarimetric and dual-wavelength ratio characterization of non-spherical particles for improved ice crystal habit identification. Examples of SACR observations from four ARM sites are presented here: the fixed sites at Southern Great Plains (SGP) and North Slope of Alaska (NSA), and the mobile facility deployments at Graciosa Island, Azores and Cape Cod, Massachusetts. The 3D cloud structure is investigated both at the macro-scale (20-50 km) and cloud-scale (100-500 m). Doppler velocity measurements are corrected for velocity folding and are used either to describe the in-cloud horizontal wind profile or the 3D vertical air motions.

  2. Qualification of Point Clouds Measured by SFM Software

    NASA Astrophysics Data System (ADS)

    Oda, K.; Hattori, S.; Saeki, H.; Takayama, T.; Honma, R.

    2015-05-01

    This paper proposes a qualification method of a point cloud created by SfM (Structure-from-Motion) software. Recently, SfM software is popular for creating point clouds. Point clouds created by SfM Software seems to be correct, but in many cases, the result does not have correct scale, or does not have correct coordinates in reference coordinate system, and in these cases it is hard to evaluate the quality of the point clouds. To evaluate this correctness of the point clouds, we propose to use the difference between point clouds with different source of images. If the shape of the point clouds with different source of images is correct, two shapes of different source might be almost same. To compare the two or more shapes of point cloud, iterative-closest-point (ICP) is implemented. Transformation parameters (rotation and translation) are iteratively calculated so as to minimize sum of squares of distances. This paper describes the procedure of the evaluation and some test results.

  3. Lost in Cloud

    NASA Technical Reports Server (NTRS)

    Maluf, David A.; Shetye, Sandeep D.; Chilukuri, Sri; Sturken, Ian

    2012-01-01

    Cloud computing can reduce cost significantly because businesses can share computing resources. In recent years Small and Medium Businesses (SMB) have used Cloud effectively for cost saving and for sharing IT expenses. With the success of SMBs, many perceive that the larger enterprises ought to move into Cloud environment as well. Government agency s stove-piped environments are being considered as candidates for potential use of Cloud either as an enterprise entity or pockets of small communities. Cloud Computing is the delivery of computing as a service rather than as a product, whereby shared resources, software, and information are provided to computers and other devices as a utility over a network. Underneath the offered services, there exists a modern infrastructure cost of which is often spread across its services or its investors. As NASA is considered as an Enterprise class organization, like other enterprises, a shift has been occurring in perceiving its IT services as candidates for Cloud services. This paper discusses market trends in cloud computing from an enterprise angle and then addresses the topic of Cloud Computing for NASA in two possible forms. First, in the form of a public Cloud to support it as an enterprise, as well as to share it with the commercial and public at large. Second, as a private Cloud wherein the infrastructure is operated solely for NASA, whether managed internally or by a third-party and hosted internally or externally. The paper addresses the strengths and weaknesses of both paradigms of public and private Clouds, in both internally and externally operated settings. The content of the paper is from a NASA perspective but is applicable to any large enterprise with thousands of employees and contractors.

  4. Classification-based scene modeling for urban point clouds

    NASA Astrophysics Data System (ADS)

    Hao, Wen; Wang, Yinghui

    2014-03-01

    The three-dimensional modeling of urban scenes is an important topic that can be used for various applications. We present a comprehensive strategy to reconstruct a scene from urban point clouds. First, the urban point clouds are classified into the ground points, planar points on the ground, and nonplanar points on the ground by using the support vector machine algorithm which takes several differential geometry properties as features. Second, the planar points and nonplanar points on the ground are segmented into patches by using different segmentation methods. A collection of characteristics of point cloud segments like height, size, topological relationship, and ratio between the width and length are applied to extract different objects after removing the unwanted segments. Finally, the buildings, ground, and trees in the scene are reconstructed, resulting in a hybrid model representing the urban scene. Experimental results demonstrate that the proposed method can be used as a robust way to reconstruct the scene from the massive point clouds.

  5. New techniques in 3D scalar and vector field visualization

    SciTech Connect

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

    1993-05-05

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

  6. Cloud Ozone Dust Imager (CODI)

    NASA Astrophysics Data System (ADS)

    Clancy, R. Todd; Dusenbery, Paul; Wolff, Michael; James, Phil; Allen, Mark; Goguen, Jay; Kahn, Ralph; Gladstone, Rany; Murphy, Jim

    1995-01-01

    pixel arrays, as partitioned on two 1024 x 1024 CCD's operated in frame transfer mode. The center of the CODI field-of-view is canted 40 deg from the zenith direction to obtain sky brightness measurements and a 20 deg surface field-of-view. Daily image observations will be conducted when the Sun is greater than or equal to 5 deg outside the edge of the CODI field-of-view, and twilight and nighttime imaging will obtained on a weekly basis. The 673 nm channel includes a polarizer wheel to obtain sky/surface polarimetry. A dust cover protects the entire lens assemblies of all four CODI channels. This opaque dust cover, which is normally opened for CODI imaging, includes a small fixed mirror and transparent window positioned above the 673 nm lens, to redirect the 673 nm field-of-view to the surface for descent imaging. Fixed pointing, internal data buffering, low operating power (2-4 W for less than or equal to 30 seconds), selective data transmission, and simple operational characteristics of the CODI experiment place minimum resource and operational demands on the Mars Surveyor 1998 lander. The CODI science goals are optimized for, but not restricted to, a low-latitude landing site (20 deg S-30 deg N). The primary CODI measurement objectives are the opacities, wave forms, particle properties (size, shape, and alignment), and heights of clouds; the opacities, particle properties, and vertical distribution of dust; and the opacity and vertical distribution of ozone. The variability of cloud, ozone, and dust opacities will be determined on diurnal, daily, and seasonal timescales. Wind velocities will be determined from cloud motions and wave characteristics; and the temporal variability of atmospheric water vapor, with limited altitude information, will be inferred from the CODI ozone observations. Secondary measurement objectives include limited descent imaging capability, surface uv-visible photometry and polarimetry, photochemistry, and meteorite infall rates.

  7. Entrainment and detrainment in a simple cumulus cloud model

    NASA Technical Reports Server (NTRS)

    Randall, D. A.; Huffman, G. J.

    1982-01-01

    A cumulus cloud model, analogous to the mixed-layer models of the planetary boundary layer and the upper ocean, is developed using a single, unitary entrainment process in which the motion of the cloud boundary relative to the mean flow is permitted, produced, and controlled by turbulent processes. An alternate theory to the mixing-length theory of Asai and Kasahara (1967) is proposed which completely removes the strong scale-dependence of the Asai-Kasahara model. The model reintroduces scale-dependence by introducing including the pe5turbation pressure term of the equation of vertical motion. It is shown that the model predicts deeper clouds than the Asai-Kasahara model for a given sounding, due to the entrainment assumption and the effects of the perturbation pressure. Lateral entrainment dominates cloud-top entrainment, although finite-difference errors increase the cloud-top entrainment rate from zero to a positive value in actual situations. The fractional entrainment rate for updrafts is determined to vary only slightly with height and to decrease only slowly as the cloud radius increases, while the fractional detrainment rate for updrafts increases with height.

  8. Cloud Resolving Modeling

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo

    2007-01-01

    One of the most promising methods to test the representation of cloud processes used in climate models is to use observations together with cloud-resolving models (CRMs). CRMs use more sophisticated and realistic representations of cloud microphysical processes, and they can reasonably well resolve the time evolution, structure, and life cycles of clouds and cloud systems (with sizes ranging from about 2-200 km). CRMs also allow for explicit interaction between clouds, outgoing longwave (cooling) and incoming solar (heating) radiation, and ocean and land surface processes. Observations are required to initialize CRMs and to validate their results. This paper provides a brief discussion and review of the main characteristics of CRMs as well as some of their major applications. These include the use of CRMs to improve our understanding of: (1) convective organization, (2) cloud temperature and water vapor budgets, and convective momentum transport, (3) diurnal variation of precipitation processes, (4) radiative-convective quasi-equilibrium states, (5) cloud-chemistry interaction, (6) aerosol-precipitation interaction, and (7) improving moist processes in large-scale models. In addition, current and future developments and applications of CRMs will be presented.

  9. On Cloud Nine

    ERIC Educational Resources Information Center

    McCrea, Bridget; Weil, Marty

    2011-01-01

    Across the U.S., innovative collaboration practices are happening in the cloud: Sixth-graders participate in literary salons. Fourth-graders mentor kindergarteners. And teachers use virtual Post-it notes to advise students as they create their own television shows. In other words, cloud computing is no longer just used to manage administrative…

  10. Weather Fundamentals: Clouds. [Videotape].

    ERIC Educational Resources Information Center

    1998

    The videos in this educational series, for grades 4-7, help students understand the science behind weather phenomena through dramatic live-action footage, vivid animated graphics, detailed weather maps, and hands-on experiments. This episode (23 minutes) discusses how clouds form, the different types of clouds, and the important role they play in…

  11. Smoke Above Clouds

    NASA Technical Reports Server (NTRS)

    Remer, Lorraine A.

    2009-01-01

    Aerosols in the atmosphere alter the radiative balance of the Earth by reflecting or absorbing solar radiation. Spaceborne measurements of clouds and aerosols advected over the southeastern Atlantic Ocean indicate that the greater the cloud cover below the aerosols, the more likely the aerosols are to heat the planet.

  12. Kernel structures for Clouds

    NASA Technical Reports Server (NTRS)

    Spafford, Eugene H.; Mckendry, Martin S.

    1986-01-01

    An overview of the internal structure of the Clouds kernel was presented. An indication of how these structures will interact in the prototype Clouds implementation is given. Many specific details have yet to be determined and await experimentation with an actual working system.

  13. Learning in the Clouds?

    ERIC Educational Resources Information Center

    Butin, Dan W.

    2013-01-01

    Engaged learning--the type that happens outside textbooks and beyond the four walls of the classroom--moves beyond right and wrong answers to grappling with the uncertainties and contradictions of a complex world. iPhones back up to the "cloud." GoogleDocs is all about "cloud computing." Facebook is as ubiquitous as the sky.…

  14. Clouds over Open Ocean

    NASA Technical Reports Server (NTRS)

    1981-01-01

    The heavy concentration of these cirrocumulus and nimbostratus clouds over open ocean - location unknown, indicate that a heavy downpouring of rain is occuring on the Earth's surface below. Towering anvils, seen rising high above the base cloud cover and casting long shadows, also indicate high winds and possible tornado activity.

  15. Cloud and Aerosol Interaction Observed in SKYNET Hefei Site in China

    NASA Astrophysics Data System (ADS)

    Wang, Yingjian; Sun, Lu; Liu, Dong; Wang, Zhien; Wang, Zhenzhu; Xie, Chenbo

    2016-06-01

    The interaction relationship between cloud and aerosol is studied via their optical depth and cloud effective radius based on ground-based remote sensors. By attenuated backscatter obtained by lidar the optical depth of cloud and aerosol is retrieved. Combing with liquid water path observed by microwave radiometer, the cloud number concentration and cloud effective radius is also retrieved based on the adiabatic hypothesis Cases studies shows that during the stable stratocumulus with interval precipitation period and aerosol with vertical motion, the cloud effective radius shows both negative and positive relationship with aerosol optical depth. It may be due to the difference of liquid water path of the cloud properties and shows complex interaction with aerosol.

  16. Redundancy, Self-Motion, and Motor Control

    PubMed Central

    Martin, V.; Scholz, J. P.; Schöner, G.

    2011-01-01

    Outside the laboratory, human movement typically involves redundant effector systems. How the nervous system selects among the task-equivalent solutions may provide insights into how movement is controlled. We propose a process model of movement generation that accounts for the kinematics of goal-directed pointing movements performed with a redundant arm. The key element is a neuronal dynamics that generates a virtual joint trajectory. This dynamics receives input from a neuronal timer that paces end-effector motion along its path. Within this dynamics, virtual joint velocity vectors that move the end effector are dynamically decoupled from velocity vectors that do not. Moreover, the sensed real joint configuration is coupled back into this neuronal dynamics, updating the virtual trajectory so that it yields to task-equivalent deviations from the dynamic movement plan. Experimental data from participants who perform in the same task setting as the model are compared in detail to the model predictions. We discover that joint velocities contain a substantial amount of self-motion that does not move the end effector. This is caused by the low impedance of muscle joint systems and by coupling among muscle joint systems due to multiarticulatory muscles. Back-coupling amplifies the induced control errors. We establish a link between the amount of self-motion and how curved the end-effector path is. We show that models in which an inverse dynamics cancels interaction torques predict too little self-motion and too straight end-effector paths. PMID:19718817

  17. Observed cloud level circulation on Venus - Temporal variations and solar longitude dependence

    NASA Technical Reports Server (NTRS)

    Limaye, Sanjay Shridhar

    1987-01-01

    This paper presents data on the atmospheric circulation of Venus, obtained by the Mariner 10 (1974) and Pioneer (1979-1986) observations. The results yielded evidence of relatively stable zonal circulation at the cloud level. On the other hand, changes on a yearly time scale appear in both the zonal and the meridional components of motion. Solar thermal tides and large-scale planetary waves are also seen in averaged zonal and meridional cloud motions. The relationship between the large-scale circulation and global cloud structure is discussed.

  18. On the Kinematics of Undulator Girder Motion

    SciTech Connect

    Welch, J; /SLAC

    2011-08-18

    The theory of rigid body kinematics is used to derive equations that govern the control and measurement of the position and orientation of undulator girders. The equations form the basis of the girder matlab software on the LCLS control system. The equations are linear for small motion and easily inverted as desired. For reference, some relevant girder geometrical data is also given. Equations 6-8 relate the linear potentiometer readings to the motion of the girder. Equations 9-11 relate the cam shaft angles to the motion of the girder. Both sets are easily inverted to either obtain the girder motion from the angles or readings, or, to find the angles and readings that would give a desired motion. The motion of any point on the girder can be calculated by applying either sets of equations to the two cam-planes and extrapolating in the z coordinate using equation 19. The formulation of the equations is quite general and easily coded via matrix and vector methods. They form the basis of the girder matlab software on the LCLS control system.

  19. Motion sickness induced by off-vertical axis rotation (OVAR)

    PubMed Central

    Sofroniou, Sofronis; Kunin, Mikhail; Raphan, Theodore; Cohen, Bernard

    2011-01-01

    We tested the hypothesis that motion sickness is produced by an integration of the disparity between eye velocity and the yaw-axis orientation vector of velocity storage. Disparity was defined as the magnitude of the cross product between these two vectors. OVAR, which is known to produce motion sickness, generates horizontal eye velocity with a bias level related to velocity storage, as well as cyclic modulations due to re-orientation of the head re gravity. On average, the orientation vector is close to the spatial vertical. Thus, disparity can be related to the bias and tilt angle. Motion sickness sensitivity was defined as a ratio of maximum motion sickness score to the number of revolutions, allowing disparity and motion sickness sensitivity to be correlated. Nine subjects were rotated around axes tilted 10°–30° from the spatial vertical at 30°/s–120°/s. Motion sickness sensitivity increased monotonically with increases in the disparity due to changes in rotational velocity and tilt angle. Maximal motion sickness sensitivity and bias (6.8°/s) occurred when rotating at 60°/s about an axis tilted 30° Modulations in eye velocity during OVAR were unrelated to motion sickness sensitivity. The data were predicted by a model incorporating an estimate of head velocity from otolith activation, which activated velocity storage, followed by an orientation disparity comparator that activated a motion sickness integrator. These results suggest that the sensory-motor conflict that produces motion sickness involves coding of the spatial vertical by the otolith organs and body tilt receptors and processing of eye velocity through velocity storage. PMID:20535456

  20. On helical vortex motions of moist air

    NASA Astrophysics Data System (ADS)

    Kurgansky, M. V.

    2013-09-01

    Two results that are fundamentally different from what takes place in a dry atmosphere have been obtained for adiabatic motions of unsaturated moist air: (1) the steady helical motion of moist air with collinear velocity and vorticity vectors everywhere is dynamically impossible; (2) the spontaneous amplification (generation) of helicity in a moist air due to baroclinicity is dynamically and thermodynamically feasible. In the absence of helicity flux through the boundary of the domain occupied by air flows, the difference between the values of integral helicity H at time instant t delaying at a small time interval from the initial instant t 0 (at which the instantaneous state of air motion is isomorphic either to a steady Beltrami flow or to an irrotational flow) and the initial value of H increases proportionally to ( t - t 0)4. The nonzero value of the proportionality factor is ensured by the difference in values of the Poisson ratio for dry air and water vapor, respectively.

  1. Io's sodium cloud

    NASA Astrophysics Data System (ADS)

    Goldberg, B. A.; Garneau, G. W.; Lavoie, S. K.

    1984-11-01

    The first two-dimensional images of the source region of Io's neutral sodium cloud have been acquired by ground-based observation. Observed asymmetries in its spatial brightness distribution provide new evidence that the cloud is supplied by sodium that is ejected nonisotropically from Io or its atmosphere. Complementary, high-time-resolution, calibrated image sequences that give the first comprehensive picture of the variations of the fainter regions of the cloud extending more than 100,000 kilometers from Io were also obtained. These data demonstrate that the cloud exhibits a persistent systematic behavior coupled with Io's orbital position, a distinct 'east-west orbital asymmetry', a variety of spatial morphologies, and true temporal changes. The geometric stability of the sodium source is also indicated. Isolation of the cloud's temporal changes constitutes an important milestone toward its utilization as a long-term probe of Io and the inner Jovian magnetosphere.

  2. SMILES ice cloud products

    NASA Astrophysics Data System (ADS)

    MilláN, L.; Read, W.; Kasai, Y.; Lambert, A.; Livesey, N.; Mendrok, J.; Sagawa, H.; Sano, T.; Shiotani, M.; Wu, D. L.

    2013-06-01

    Upper tropospheric water vapor and clouds play an important role in Earth's climate, but knowledge of them, in particular diurnal variation in deep convective clouds, is limited. An essential variable to understand them is cloud ice water content. The Japanese Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) on board the International Space Station (ISS) samples the atmosphere at different local times allowing the study of diurnal variability of atmospheric parameters. We describe a new ice cloud data set consisting of partial Ice Water Path and Ice Water Content. Preliminary comparisons with EOS-MLS, CloudSat-CPR and CALIOP-CALIPSO are presented. Then, the diurnal variation over land and over open ocean for partial ice water path is reported. Over land, a pronounced diurnal variation peaking strongly in the afternoon/early evening was found. Over the open ocean, little temporal dependence was encountered. This data set is publicly available for download in HDF5 format.

  3. Cloud computing security.

    SciTech Connect

    Shin, Dongwan; Claycomb, William R.; Urias, Vincent E.

    2010-10-01

    Cloud computing is a paradigm rapidly being embraced by government and industry as a solution for cost-savings, scalability, and collaboration. While a multitude of applications and services are available commercially for cloud-based solutions, research in this area has yet to fully embrace the full spectrum of potential challenges facing cloud computing. This tutorial aims to provide researchers with a fundamental understanding of cloud computing, with the goals of identifying a broad range of potential research topics, and inspiring a new surge in research to address current issues. We will also discuss real implementations of research-oriented cloud computing systems for both academia and government, including configuration options, hardware issues, challenges, and solutions.

  4. Polarization of clouds

    NASA Astrophysics Data System (ADS)

    Goloub, Philippe; Herman, Maurice; Parol, Frederic

    1995-12-01

    This paper reports the main results concerning polarization by clouds derived from POLDER (polarization and directionality of earth's reflectances) airborne version. These results tend to confirm the high information content in the polarization (phase, altimetry). The preliminary results of EUCREX'94 (European Cloud Radiation Experiment) evidenced the drastically different polarized signatures for ice crystals and water droplets. Here we report systematic and statistically significative observations over the whole EUCREX data set. The results show that the cirrus exhibit their own signature. Preliminary observations performed during CLEOPATRA'91 (Cloud Experiment Ober Pfaffenhofen And Transport) and EUCREX'94 campaigns have shown the feasibility of cloud altimetry using spectral information (443 nm and 865 nm) of the polarized light over liquid water droplets clouds. Altimetry technique has been generalized on ASTEX-SOFIA'92 and EUCREX'94 data sets. All these results are presented and discussed in this paper.

  5. Cloud model bat algorithm.

    PubMed

    Zhou, Yongquan; Xie, Jian; Li, Liangliang; Ma, Mingzhi

    2014-01-01

    Bat algorithm (BA) is a novel stochastic global optimization algorithm. Cloud model is an effective tool in transforming between qualitative concepts and their quantitative representation. Based on the bat echolocation mechanism and excellent characteristics of cloud model on uncertainty knowledge representation, a new cloud model bat algorithm (CBA) is proposed. This paper focuses on remodeling echolocation model based on living and preying characteristics of bats, utilizing the transformation theory of cloud model to depict the qualitative concept: "bats approach their prey." Furthermore, Lévy flight mode and population information communication mechanism of bats are introduced to balance the advantage between exploration and exploitation. The simulation results show that the cloud model bat algorithm has good performance on functions optimization. PMID:24967425

  6. Prebiotic chemistry in clouds

    NASA Technical Reports Server (NTRS)

    Oberbeck, Verne R.; Marshall, John; Shen, Thomas

    1991-01-01

    The chemical evolution hypothesis of Woese (1979), according to which prebiotic reactions occurred rapidly in droplets in giant atmospheric reflux columns was criticized by Scherer (1985). This paper proposes a mechanism for prebiotic chemistry in clouds that answers Scherer's concerns and supports Woese's hypothesis. According to this mechanism, rapid prebiotic chemical evolution was facilitated on the primordial earth by cycles of condensation and evaporation of cloud drops containing clay condensation nuclei and nonvolatile monomers. For example, amino acids supplied by, or synthesized during entry of meteorites, comets, and interplanetary dust, would have been scavenged by cloud drops containing clay condensation nuclei and would be polymerized within cloud systems during cycles of condensation, freezing, melting, and evaporation of cloud drops.

  7. Essay on Gyroscopic Motions.

    ERIC Educational Resources Information Center

    Tea, Peter L., Jr.

    1988-01-01

    Explains gyroscopic motions to college freshman or high school seniors who have learned about centripetal acceleration and the transformations of a couple. Contains several figures showing the direction of forces and motion. (YP)

  8. Relationship between cloud radiative forcing, cloud fraction and cloud albedo, and new surface-based approach for determining cloud albedo

    SciTech Connect

    Liu, Y.; Wu, W.; Jensen, M. P.; Toto, T.

    2011-07-21

    This paper focuses on three interconnected topics: (1) quantitative relationship between surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo; (2) surface-based approach for measuring cloud albedo; (3) multiscale (diurnal, annual and inter-annual) variations and covariations of surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo. An analytical expression is first derived to quantify the relationship between cloud radiative forcing, cloud fraction, and cloud albedo. The analytical expression is then used to deduce a new approach for inferring cloud albedo from concurrent surface-based measurements of downwelling surface shortwave radiation and cloud fraction. High-resolution decade-long data on cloud albedos are obtained by use of this surface-based approach over the US Department of Energy's Atmospheric Radiaton Measurement (ARM) Program at the Great Southern Plains (SGP) site. The surface-based cloud albedos are further compared against those derived from the coincident GOES satellite measurements. The three long-term (1997-2009) sets of hourly data on shortwave cloud radiative forcing, cloud fraction and cloud albedo collected over the SGP site are analyzed to explore the multiscale (diurnal, annual and inter-annual) variations and covariations. The analytical formulation is useful for diagnosing deficiencies of cloud-radiation parameterizations in climate models.

  9. Respiratory motion correction in 4D-PET by simultaneous motion estimation and image reconstruction (SMEIR)

    NASA Astrophysics Data System (ADS)

    Kalantari, Faraz; Li, Tianfang; Jin, Mingwu; Wang, Jing

    2016-08-01

    In conventional 4D positron emission tomography (4D-PET), images from different frames are reconstructed individually and aligned by registration methods. Two issues that arise with this approach are as follows: (1) the reconstruction algorithms do not make full use of projection statistics; and (2) the registration between noisy images can result in poor alignment. In this study, we investigated the use of simultaneous motion estimation and image reconstruction (SMEIR) methods for motion estimation/correction in 4D-PET. A modified ordered-subset expectation maximization algorithm coupled with total variation minimization (OSEM-TV) was used to obtain a primary motion-compensated PET (pmc-PET) from all projection data, using Demons derived deformation vector fields (DVFs) as initial motion vectors. A motion model update was performed to obtain an optimal set of DVFs in the pmc-PET and other phases, by matching the forward projection of the deformed pmc-PET with measured projections from other phases. The OSEM-TV image reconstruction was repeated using updated DVFs, and new DVFs were estimated based on updated images. A 4D-XCAT phantom with typical FDG biodistribution was generated to evaluate the performance of the SMEIR algorithm in lung and liver tumors with different contrasts and different diameters (10–40 mm). The image quality of the 4D-PET was greatly improved by the SMEIR algorithm. When all projections were used to reconstruct 3D-PET without motion compensation, motion blurring artifacts were present, leading up to 150% tumor size overestimation and significant quantitative errors, including 50% underestimation of tumor contrast and 59% underestimation of tumor uptake. Errors were reduced to less than 10% in most images by using the SMEIR algorithm, showing its potential in motion estimation/correction in 4D-PET.

  10. Respiratory motion correction in 4D-PET by simultaneous motion estimation and image reconstruction (SMEIR).

    PubMed

    Kalantari, Faraz; Li, Tianfang; Jin, Mingwu; Wang, Jing

    2016-08-01

    In conventional 4D positron emission tomography (4D-PET), images from different frames are reconstructed individually and aligned by registration methods. Two issues that arise with this approach are as follows: (1) the reconstruction algorithms do not make full use of projection statistics; and (2) the registration between noisy images can result in poor alignment. In this study, we investigated the use of simultaneous motion estimation and image reconstruction (SMEIR) methods for motion estimation/correction in 4D-PET. A modified ordered-subset expectation maximization algorithm coupled with total variation minimization (OSEM-TV) was used to obtain a primary motion-compensated PET (pmc-PET) from all projection data, using Demons derived deformation vector fields (DVFs) as initial motion vectors. A motion model update was performed to obtain an optimal set of DVFs in the pmc-PET and other phases, by matching the forward projection of the deformed pmc-PET with measured projections from other phases. The OSEM-TV image reconstruction was repeated using updated DVFs, and new DVFs were estimated based on updated images. A 4D-XCAT phantom with typical FDG biodistribution was generated to evaluate the performance of the SMEIR algorithm in lung and liver tumors with different contrasts and different diameters (10-40 mm). The image quality of the 4D-PET was greatly improved by the SMEIR algorithm. When all projections were used to reconstruct 3D-PET without motion compensation, motion blurring artifacts were present, leading up to 150% tumor size overestimation and significant quantitative errors, including 50% underestimation of tumor contrast and 59% underestimation of tumor uptake. Errors were reduced to less than 10% in most images by using the SMEIR algorithm, showing its potential in motion estimation/correction in 4D-PET. PMID:27385378

  11. Isentropic Analysis of Convective Motions

    NASA Technical Reports Server (NTRS)

    Pauluis, Olivier M.; Mrowiec, Agnieszka A.

    2013-01-01

    This paper analyzes the convective mass transport by sorting air parcels in terms of their equivalent potential temperature to determine an isentropic streamfunction. By averaging the vertical mass flux at a constant value of the equivalent potential temperature, one can compute an isentropic mass transport that filters out reversible oscillatory motions such as gravity waves. This novel approach emphasizes the fact that the vertical energy and entropy transports by convection are due to the combination of ascending air parcels with high energy and entropy and subsiding air parcels with lower energy and entropy. Such conditional averaging can be extended to other dynamic and thermodynamic variables such as vertical velocity, temperature, or relative humidity to obtain a comprehensive description of convective motions. It is also shown how this approach can be used to determine the mean diabatic tendencies from the three-dimensional dynamic and thermodynamic fields. A two-stream approximation that partitions the isentropic circulation into a mean updraft and a mean downdraft is also introduced. This offers a straightforward way to identify the mean properties of rising and subsiding air parcels. The results from the two-stream approximation are compared with two other definitions of the cloud mass flux. It is argued that the isentropic analysis offers a robust definition of the convective mass transport that is not tainted by the need to arbitrarily distinguish between convection and its environment, and that separates the irreversible convective overturning fromoscillations associated with gravity waves.

  12. Vector WIMP miracle

    NASA Astrophysics Data System (ADS)

    Abe, Tomohiro; Kakizaki, Mitsuru; Matsumoto, Shigeki; Seto, Osamu

    2012-07-01

    Weakly interacting massive particle (WIMP) is well known to be a good candidate for dark matter, and it is also predicted by many new physics models beyond the standard model at the TeV scale. We found that, if the WIMP is a vector particle (spin-one particle) which is associated with some gauge symmetry broken at the TeV scale, the Higgs mass is often predicted to be 120-125 GeV, which is very consistent with the result of Higgs searches recently reported by ATLAS and CMS Collaborations at the Large Hadron Collider experiment. In this Letter, we consider the vector WIMP using a non-linear sigma model in order to confirm this result as general as possible in a bottom-up approach. Near-future prospects to detect the vector WIMP at both direct and indirect detection experiments of dark matter are also discussed.

  13. Vector financial rogue waves

    NASA Astrophysics Data System (ADS)

    Yan, Zhenya

    2011-11-01

    The coupled nonlinear volatility and option pricing model presented recently by Ivancevic is investigated, which generates a leverage effect, i.e., stock volatility is (negatively) correlated to stock returns, and can be regarded as a coupled nonlinear wave alternative of the Black-Scholes option pricing model. In this Letter, we analytically propose vector financial rogue waves of the coupled nonlinear volatility and option pricing model without an embedded w-learning. Moreover, we exhibit their dynamical behaviors for chosen different parameters. The vector financial rogue wave (rogon) solutions may be used to describe the possible physical mechanisms for the rogue wave phenomena and to further excite the possibility of relative researches and potential applications of vector rogue waves in the financial markets and other related fields.

  14. Vectorized garbage collection

    SciTech Connect

    Appel, A.W.; Bendiksen, A.

    1988-01-01

    Garbage collection can be done in vector mode on supercomputers like the Cray-2 and the Cyber 205. Both copying collection and mark-and-sweep can be expressed as breadth-first searches in which the queue can be processed in parallel. The authors have designed a copying garbage collector whose inner loop works entirely in vector mode. The only significant limitation of the algorithm is that if the size of the records is not constant, the implementation becomes much more complicated. The authors give performance measurements of the algorithm as implemented for Lisp CONS cells on the Cyber 205. Vector-mode garbage collection performs up to 9 times faster than scalar-mode collection.

  15. Guiding Center Motion

    SciTech Connect

    Blank, H.J. de

    2004-03-15

    The motion of charged particles in slowly varying electromagnetic fields is analyzed. The strength of the magnetic field is such that the gyro-period and the gyro-radius of the particle motion around field lines are the shortest time and length scales of the system. The particle motion is described as the sum of a fast gyro-motion and a slow drift velocity.

  16. Clouds Over the North Pole

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Released 29 June 2004 The atmosphere of Mars is a dynamic system. Water-ice clouds, fog, and hazes can make imaging the surface from space difficult. Dust storms can grow from local disturbances to global sizes, through which imaging is impossible. Seasonal temperature changes are the usual drivers in cloud and dust storm development and growth.

    Eons of atmospheric dust storm activity has left its mark on the surface of Mars. Dust carried aloft by the wind has settled out on every available surface; sand dunes have been created and moved by centuries of wind; and the effect of continual sand-blasting has modified many regions of Mars, creating yardangs and other unusual surface forms.

    Like yesterday's image, the linear 'ripples' are water-ice clouds. As spring is deepening at the North Pole these clouds are becoming more prevalent.

    Image information: VIS instrument. Latitude 68.9, Longitude 135.5 East (224.5 West). 38 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter

  17. Objects in Motion

    ERIC Educational Resources Information Center

    Damonte, Kathleen

    2004-01-01

    One thing scientists study is how objects move. A famous scientist named Sir Isaac Newton (1642-1727) spent a lot of time observing objects in motion and came up with three laws that describe how things move. This explanation only deals with the first of his three laws of motion. Newton's First Law of Motion says that moving objects will continue…

  18. Bunyavirus-Vector Interactions

    PubMed Central

    Horne, Kate McElroy; Vanlandingham, Dana L.

    2014-01-01

    The Bunyaviridae family is comprised of more than 350 viruses, of which many within the Hantavirus, Orthobunyavirus, Nairovirus, Tospovirus, and Phlebovirus genera are significant human or agricultural pathogens. The viruses within the Orthobunyavirus, Nairovirus, and Phlebovirus genera are transmitted by hematophagous arthropods, such as mosquitoes, midges, flies, and ticks, and their associated arthropods not only serve as vectors but also as virus reservoirs in many cases. This review presents an overview of several important emerging or re-emerging bunyaviruses and describes what is known about bunyavirus-vector interactions based on epidemiological, ultrastructural, and genetic studies of members of this virus family. PMID:25402172

  19. Scalar-vector bootstrap

    NASA Astrophysics Data System (ADS)

    Rejon-Barrera, Fernando; Robbins, Daniel

    2016-01-01

    We work out all of the details required for implementation of the conformal bootstrap program applied to the four-point function of two scalars and two vectors in an abstract conformal field theory in arbitrary dimension. This includes a review of which tensor structures make appearances, a construction of the projectors onto the required mixed symmetry representations, and a computation of the conformal blocks for all possible operators which can be exchanged. These blocks are presented as differential operators acting upon the previously known scalar conformal blocks. Finally, we set up the bootstrap equations which implement crossing symmetry. Special attention is given to the case of conserved vectors, where several simplifications occur.

  20. The 27-28 October 1986 FIRE cirrus case study - Meteorology and clouds. [First International Satellite Cloud Climatology Project Regional Experiment

    NASA Technical Reports Server (NTRS)

    Starr, David O'C.; Wylie, Donald P.

    1990-01-01

    A detailed case study is conducted of cirrus clouds that were observed intensely over a 36-h period from 1200 UTC October 27 to 0000 UTC October 29, 1986. The clouds varied in density and structure as synoptic and mesoscale features passed through the region. The study seeks to provide a meteorological overview including a synoptic and regional perspective; to document the rawinsonde-resolved atmospheric structure and large-scale forcing associated with the observed cloud systems; and to provide understanding of the relationship between atmospheric structure and the character of the corresponding cloud fields. Regional analyses of the static stability structure and vertical motion are presented and interpreted with respect to the characteristics of the corresponding cloud fields as deduced from satellite and lidar observations. It is suggested that mesoscale organization must be taken into account in parametric treatments of cirrus for large-scale atmospheric models. It is shown that cloud generation typically occurred at multiple levels.

  1. Effects on non-linearities on aircraft poststall motion

    SciTech Connect

    Rohacs, J.; Thomasson, P.; Mosehilde, E.

    1994-12-31

    The poststall maneuverability controlled by thrust vectoring has become one of the important aspects of new fighter development projects. In simplified case, the motion of aircraft can be described by 6DOF nonlinear system. The lecture deals with the longitudinal motion of poststall maneuverable aircraft. The investigation made about the effects of non-linearities in aerodynamic coefficients having considerable non-linearities and hysteresisis an the poststall motions. There were used some different models of aerodynamic coefficients. The results of investigation have shown that the poststall domain of vectored aircraft can be divided into five different pHs in field of thrust - pitch vector angle, and the chaotic motions of aircraft can be found at the different frequencies of thrust deflection. There were defined an unstable right domain with an unstable oscillation and a field of overpulling at poststall motion. The certain frequency chaotic attractors were got at frequencies of Oxitation between the 0.15 and 0.65 rad/sec. The pitching moment derivatives had the big influence on the chaotic motions, while the lift coefficient derivatives bad the reasonable effects, only.

  2. Mathematical model of formation of Kordylewski cosmic dust clouds

    NASA Astrophysics Data System (ADS)

    Sal'nikova, T. V.; Stepanov, S. Ya.

    2015-07-01

    The question of occurrence of cosmic dust clouds, which were found by Kordylewski in 1961 in the vicinity of libration point L 5 of the Earth-Moon system, still causes debates and concern. We explain theoretically the phenomenon of the apparent vanishing and appearance of the Kordylewski cosmic dust clouds in the vicinity of triangular libration points L 4 and L 5 of the Earth-Moon system. The possibility of occurrence of two such clouds rotating around libration points L 4 and two clouds rotating around point L 5 is shown and optimal times for their observation from the Earth are determined. The investigation is performed based on analysis of a stable periodic motion in a planar restricted circular problem of three bodies, Earth-Moon—Particle, allowing for perturbations from the Sun under the assumption that the orbits of the Earth and Moon are circular and lie in one plane.

  3. Precipitation growth in convective clouds. [hail

    NASA Technical Reports Server (NTRS)

    Srivastava, R. C.

    1981-01-01

    Analytical solutions to the equations of both the growth and motion of hailstones in updrafts and of cloud water contents which vary linearly with height were used to investigate hail growth in a model cloud. A strong correlation was found between the hail embyro starting position and its trajectory and final size. A simple model of the evolution of particle size distribution by coalescence and spontaneous and binary disintegrations was formulated. Solutions for the mean mass of the distribution and the equilibrium size distribution were obtained for the case of constant collection kernel and disintegration parameters. Azimuthal scans of Doppler velocity at a number of elevation angles were used to calculate high resolution vertical profiles of particle speed and horizontal divergence (the vertical air velocity) in a region of widespread precipitation trailing a mid-latitude squall line.

  4. O VI absorption in interstellar cloud surfaces

    NASA Technical Reports Server (NTRS)

    Cowie, L. L.; Jenkins, E. B.; Songaila, A.; York, D. G.

    1979-01-01

    The velocity profiles of O VI absorption lines of 24 stars, observed in early Copernicus surveys, have been compared with the line profiles of Si III (1206.51 A) and N II (1083.99 A). The velocity structures of the O VI lines appear to be correlated with those of the material in the lower ionization stages. It is argued that the O VI absorption arises in the coronal gas of the conductive interface between hot gas, responsible for extended, soft X-ray emission, and cooler interstellar clouds. The velocity broadening of both sets of lines is attributed to motions of the cloud surfaces induced by pressure fluctuations in the interstellar medium.

  5. Community Cloud Computing

    NASA Astrophysics Data System (ADS)

    Marinos, Alexandros; Briscoe, Gerard

    Cloud Computing is rising fast, with its data centres growing at an unprecedented rate. However, this has come with concerns over privacy, efficiency at the expense of resilience, and environmental sustainability, because of the dependence on Cloud vendors such as Google, Amazon and Microsoft. Our response is an alternative model for the Cloud conceptualisation, providing a paradigm for Clouds in the community, utilising networked personal computers for liberation from the centralised vendor model. Community Cloud Computing (C3) offers an alternative architecture, created by combing the Cloud with paradigms from Grid Computing, principles from Digital Ecosystems, and sustainability from Green Computing, while remaining true to the original vision of the Internet. It is more technically challenging than Cloud Computing, having to deal with distributed computing issues, including heterogeneous nodes, varying quality of service, and additional security constraints. However, these are not insurmountable challenges, and with the need to retain control over our digital lives and the potential environmental consequences, it is a challenge we must pursue.

  6. Clouds in GEOS-5

    NASA Technical Reports Server (NTRS)

    Bacmeister, Julio; Rienecker, Michele; Suarez, Max; Norris, Peter

    2007-01-01

    The GEOS-5 atmospheric model is being developed as a weather-and-climate capable model. It must perform well in assimilation mode as well as in weather and climate simulations and forecasts and in coupled chemistry-climate simulations. In developing GEOS-5, attention has focused on the representation of moist processes. The moist physics package uses a single phase prognostic condensate and a prognostic cloud fraction. Two separate cloud types are distinguished by their source: "anvil" cloud originates in detraining convection, and large-scale cloud originates in a PDF-based condensation calculation. Ice and liquid phases for each cloud type are considered. Once created, condensate and fraction from the anvil and statistical cloud types experience the same loss processes: evaporation of condensate and fraction, auto-conversion of liquid or mixed phase condensate, sedimentation of frozen condensate, and accretion of condensate by falling precipitation. The convective parameterization scheme is the Relaxed Arakawa-Schubert, or RAS, scheme. Satellite data are used to evaluate the performance of the moist physics packages and help in their tuning. In addition, analysis of and comparisons to cloud-resolving models such as the Goddard Cumulus Ensemble model are used to help improve the PDFs used in the moist physics. The presentation will show some of our evaluations including precipitation diagnostics.

  7. Production of lentiviral vectors

    PubMed Central

    Merten, Otto-Wilhelm; Hebben, Matthias; Bovolenta, Chiara

    2016-01-01

    Lentiviral vectors (LV) have seen considerably increase in use as gene therapy vectors for the treatment of acquired and inherited diseases. This review presents the state of the art of the production of these vectors with particular emphasis on their large-scale production for clinical purposes. In contrast to oncoretroviral vectors, which are produced using stable producer cell lines, clinical-grade LV are in most of the cases produced by transient transfection of 293 or 293T cells grown in cell factories. However, more recent developments, also, tend to use hollow fiber reactor, suspension culture processes, and the implementation of stable producer cell lines. As is customary for the biotech industry, rather sophisticated downstream processing protocols have been established to remove any undesirable process-derived contaminant, such as plasmid or host cell DNA or host cell proteins. This review compares published large-scale production and purification processes of LV and presents their process performances. Furthermore, developments in the domain of stable cell lines and their way to the use of production vehicles of clinical material will be presented. PMID:27110581

  8. Support vector machines

    NASA Technical Reports Server (NTRS)

    Garay, Michael J.; Mazzoni, Dominic; Davies, Roger; Wagstaff, Kiri

    2004-01-01

    Support Vector Machines (SVMs) are a type of supervised learning algorith,, other examples of which are Artificial Neural Networks (ANNs), Decision Trees, and Naive Bayesian Classifiers. Supervised learning algorithms are used to classify objects labled by a 'supervisor' - typically a human 'expert.'.

  9. Singular Vectors' Subtle Secrets

    ERIC Educational Resources Information Center

    James, David; Lachance, Michael; Remski, Joan

    2011-01-01

    Social scientists use adjacency tables to discover influence networks within and among groups. Building on work by Moler and Morrison, we use ordered pairs from the components of the first and second singular vectors of adjacency matrices as tools to distinguish these groups and to identify particularly strong or weak individuals.

  10. Killing vectors and anisotropy

    SciTech Connect

    Krisch, J. P.; Glass, E. N.

    2009-08-15

    We consider an action that can generate fluids with three unequal stresses for metrics with a spacelike Killing vector. The parameters in the action are directly related to the stress anisotropies. The field equations following from the action are applied to an anisotropic cosmological expansion and an extension of the Gott-Hiscock cosmic string.

  11. Vector-borne diseases.

    PubMed

    Gubler, D J

    2009-08-01

    Vector-borne diseases have been the scourge of man and animals since the beginning of time. Historically, these are the diseases that caused the great plagues such as the 'Black Death' in Europe in the 14th Century and the epidemics of yellow fever that plagued the development of the New World. Others, such as Nagana, contributed to the lack of development in Africa for many years. At the turn of the 20th Century, vector-borne diseases were among the most serious public and animal health problems in the world. For the most part, these diseases were controlled by the middle of the 20th Century through the application of knowledge about their natural history along with the judicious use of DDT (dichlorodiphenyltrichloroethane) and other residual insecticides to interrupt the transmission cycle between arthropod and vertebrate host. However, this success initiated a period of complacency in the 1960s and 1970s, which resulted in the redirection of resources away from prevention and control of vector-borne diseases. The 1970s was also a time in which there were major changes to public health policy. Global trends, combined with changes in animal husbandry, urbanisation, modern transportation and globalisation, have resulted in a global re-emergence of epidemic vector-borne diseases affecting both humans and animals over the past 30 years. PMID:20128467

  12. Research in vector control

    PubMed Central

    Quarterman, K. D.

    1963-01-01

    Current research on vector control is directed mainly at finding answers to the problem of resistance. Despite considerable advances in knowledge of the genetics, biochemistry, physiology, and ecology of resistant vectors, the only practical answer found so far has been the development of new, substitute insecticides. At present the operational needs of existing large-scale control or eradication programmes swallow up much of the funds, personnel and facilities that might otherwise be devoted to basic research. Moreover, to back up these programmes, there is a continuing need for applied research on such questions as the packaging of pesticides, improvements in equipment and the development of new formulations. The author gives examples of applied research already carried out or in progress and indicates some areas of both basic and applied research demanding urgent attention. Like other participants in the seminar, he stresses the fundamental importance of ecological studies. He also examines the concept of integrated vector control and points out that the realization of this concept presupposes close co-ordination between basic and applied research, laboratory and field studies, and investigations on chemical and non-chemical vector control measures. PMID:20604177

  13. Diagnosing AIRS Sampling with CloudSat Cloud Classes

    NASA Technical Reports Server (NTRS)

    Fetzer, Eric; Yue, Qing; Guillaume, Alexandre; Kahn, Brian

    2011-01-01

    AIRS yield and sampling vary with cloud state. Careful utilization of collocated multiple satellite sensors is necessary. Profile differences between AIRS and ECMWF model analyses indicate that AIRS has high sampling and excellent accuracy for certain meteorological conditions. Cloud-dependent sampling biases may have large impact on AIRS L2 and L3 data in climate research. MBL clouds / lower tropospheric stability relationship is one example. AIRS and CloudSat reveal a reasonable climatology in the MBL cloud regime despite limited sampling in stratocumulus. Thermodynamic parameters such as EIS derived from AIRS data map these cloud conditions successfully. We are working on characterizing AIRS scenes with mixed cloud types.

  14. Aerosol-cloud closure study using RPAS measurements

    NASA Astrophysics Data System (ADS)

    Calmer, R.; Roberts, G.; Sanchez, K. J.; Nicoll, K.; Preissler, J.; Ovadnevaite, J.; Sciare, J.; Bronz, M.; Hattenberger, G.; Rosenfeld, D.; Lauda, S.; Hashimshoni, E.

    2015-12-01

    Enhancements in Remotely Piloted Aircraft Systems (RPAS) have increased their possible uses in many fields for the past two decades. For atmospheric research, ultra-light RPAS (< 2.5kg) are now able to fly at altitudes greater than 3 km and even in cloud, which opens new opportunities to understand aerosol-cloud interactions. We are deploying the RPAS as part of the European project BACCHUS (Impact of Biogenic versus Anthropogenic Emissions on Clouds and Climate: towards a Holistic Understanding). Field experiments in Cyprus and Ireland have already been conducted to study aerosol-cloud interactions in climatically different environments. The RPAS are being utilized in this study with the purpose of complementing ground-based observations of cloud condensation nuclei (CCN) to conduct aerosol-cloud closure studies Cloud microphysical properties such as cloud drop number concentration and size can be predicted directly from the measured CCN spectrum and the observed updraft, the vertical component of the wind vector [e.g., Conant et al, 2004]. On the RPAS, updraft measurements are obtained from a 5-hole probe synchronized with an Inertial Measurement Unit (IMU). The RPA (remotely piloted aircraft) are programmed to fly at a level leg just below cloud base to measure updraft measurements while a scanning CCN counter is stationed at ground level. Vertical profiles confirm that CCN measurements on the ground are representative to those at cloud base. An aerosol-cloud parcel model is implemented to model the cloud droplet spectra associated with measured updraft velocities. The model represents the particle size domain with internally mixed chemical components, using a fixed-sectional approach [L. M. Russell and Seinfeld, 1998]. The model employs a dual moment (number and mass) algorithm to calculate growth of particles from one section to the next for non-evaporating species. Temperature profiles, cloud base, updraft velocities and aerosol size and composition, all

  15. DISPERSION OF MAGNETIC FIELDS IN MOLECULAR CLOUDS. I

    SciTech Connect

    Hildebrand, Roger H.; Kirby, Larry; Dotson, Jessie L.; Houde, Martin; Vaillancourt, John E.

    2009-05-01

    We describe a method for determining the dispersion of magnetic field vectors about large-scale fields in turbulent molecular clouds. The method is designed to avoid inaccurate estimates of magnetohydrodynamic or turbulent dispersion-and help avoiding inaccurate estimates of field strengths-due to a large-scale, nonturbulent field structure when using the well known method of Chandrasekhar and Fermi. Our method also provides accurate, independent estimates of the turbulent to large-scale magnetic field strength ratio. We discuss applications to the molecular clouds OMC-1, M17, and DR21(Main)

  16. A numerical model of electrodynamics of plasma within the contaminant gas cloud of the Space Shuttle Orbiter at low earth orbit

    NASA Technical Reports Server (NTRS)

    Eccles, J. Vincent; Raitt, W. John; Banks, Peter M.

    1989-01-01

    A two-dimensional cloud was used to study the plasma dynamics within the outgas cloud associated with the Orbiter. It is shown that the polarization field is not symmetric about the direction of motion of the outgas cloud. It rotates in a way that can be predicted in simple cases by the ratio of the Hall and Pederson currents within the outgas cloud. The polarization field magnitude produced in the model was not large.

  17. Long-term monitoring of structures through point cloud analysis

    NASA Astrophysics Data System (ADS)

    Jafari, Bahman; Khaloo, Ali; Lattanzi, David

    2016-04-01

    Modern remote sensing technologies have enabled the creation of high-resolution 3D point clouds of infrastructure systems. In particular, photogrammetric reconstructions using Dense-Structure-from-Motion algorithm can now yield point clouds with the necessary resolution to capture small-strain displacements. By tracking changes in these point clouds over time, displacements can be measured, leading to strain and stress estimates for long-term structural evaluations. This study determines the accuracy of a comparative point cloud analysis technique for measuring deflections in high-resolution point clouds of structural elements. Utilizing a combination of a recently developed point cloud generation process and localized nearest-neighbors cloud comparisons, the analytical technique is designed for long-term field scenarios and requires no artificial tracking, targets, and camera calibrations. A series of flexural laboratory experiments were performed in order to test the approach. The results indicate sub-millimeter accuracy in measuring the vertical deflection, making it suitable for the small-displacement analysis of a variety of large-scale infrastructure systems. Ongoing work seeks to extend this technique for comparison with as-built and finite element models.

  18. Cloud computing basics for librarians.

    PubMed

    Hoy, Matthew B

    2012-01-01

    "Cloud computing" is the name for the recent trend of moving software and computing resources to an online, shared-service model. This article briefly defines cloud computing, discusses different models, explores the advantages and disadvantages, and describes some of the ways cloud computing can be used in libraries. Examples of cloud services are included at the end of the article. PMID:22289098

  19. Nighttime Clouds in Martian Arctic (Accelerated Movie)

    NASA Technical Reports Server (NTRS)

    2008-01-01

    An angry looking sky is captured in a movie clip consisting of 10 frames taken by the Surface Stereo Imager on NASA's Phoenix Mars Lander.

    The clip accelerates the motion. The images were take around 3 a.m. local solar time at the Phoenix site during Sol 95 (Aug. 30), the 95th Martian day since landing.

    The swirling clouds may be moving generally in a westward direction over the lander.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  20. A New Approach to Using a Cloud-resolving Model to Study the Interactions Between Clouds, Precipitation and Aerosols

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo

    2005-01-01

    Numerical cloud models, which are based the non-hydrostatic equations of motion, have been extensively applied to cloud-scale and mesoscale processes during the past four decades. Because cloud-scale dynamics are treated explicitly, uncertainties stemming from convection that have to be parameterized in (hydrostatic) large-scale models are obviated, or at least mitigated, in cloud models. Global models will use the non-hydrostatic framework when their horizontal resolution becomes about 10 km, the theoretical limit for the hydrostatic approximation. This juncture will be reached one to two decades from now. Over the past generation, voluminous datasets on atmospheric convection have been accumulated from radar, instrumented aircraft, satellites, and rawinsonde measurements in field campaigns, enabling the detailed evaluation of models. Improved numerical methods have resulted in more accurate and efficient dynamical cores in models. Improvements have been made in the parameterizations of microphysical processes, radiation, boundary-layer effects, and turbulence; however, microphysical parameterizations remain a major source of uncertainty in all classes of atmospheric models. In recent years, exponentially increasing computer power has extended cloud-resolving-model integrations from hours to months, the number of computational grid points from less than a thousand to close to ten million. Three-dimensional models are now more prevalent. Much attention is devoted to precipitating cloud systems where the crucial 1-km scales are resolved in horizontal domains as large as l0,OOO km in two-dimensions, and 1,OOO x 1,OOO km2 in three-dimensions. Cloud models now provide statistical information useful for developing more realistic physically-based parameterizations for climate models and numerical weather prediction models. A review of developments and applications of cloud models in the past, present and future will be presented in this talk. In particular, a new

  1. A New Approach to using a Cloud-Resolving Model to Study the Interactions between Clouds, Precipitation and Aerosols

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo

    2005-01-01

    Numerical cloud models, which are based the non-hydrostatic equations of motion, have been extensively applied to cloud-scale and mesoscale processes during the past four decades. Because cloud-scale dynamics are treated explicitly, uncertainties stemming from convection that have to be parameterized in (hydrostatic) large-scale models are obviated, or at least mitigated, in cloud models. Global models will use the non-hydrostatic framework when their horizontal resolution becomes about 10 km, the theoretical limit for the hydrostatic approximation. This juncture will be reached one to two decades from now. Over the past generation, voluminous datasets on atmospheric convection have been accumulated from radar, instrumented aircraft, satellites, and rawinsonde measurements in field campaigns, enabling the detailed evaluation of models. Improved numerical methods have resulted in more accurate and efficient dynamical cores in models. Improvements have been made in the parameterizations of microphysical processes, radiation, boundary-layer effects, and turbulence; however, microphysical parameterizations remain a major source of uncertainty in all classes of atmospheric models. In recent years, exponentially increasing computer power has extended cloud-resolving-model integrations from hours to months, the number of computational grid points from less than a thousand to close to ten million. Three-dimensional models are now more prevalent. Much attention is devoted to precipitating cloud systems where the crucial 1-km scales are resolved in horizontal domains as large as 10,000 km in two-dimensions, and 1,000 x 1,000 square kilometers in three-dimensions. Cloud models now provide statistical information useful for developing more realistic physically-based parameterizations for climate models and numerical weather prediction models. A review of developments and applications of cloud models in the past, present and future will be presented in this talk. In particular

  2. A New Approach to using a Cloud-Resolving Model to Study the Interactions between Clouds, Precipitation and Aerosols

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo

    2005-01-01

    Numerical cloud models, which are based the non-hydrostatic equations of motion, have been extensively applied to cloud-scale and mesoscale processes during the past four decades. Because cloud-scale dynamics are treated explicitly, uncertainties stemming from convection that have to be parameterized in (hydrostatic) large-scale models are obviated, or at least mitigated, in cloud models. Global models will use the non-hydrostatic framework when their horizontal resolution becomes about 10 kilometers, the theoretical limit for the hydrostatic approximation. This juncture will be reached one to two decades from now. Over the past generation, voluminous datasets on atmospheric convection have been accumulated from radar, instrumented aircraft, satellites, and rawinsonde measurements in field campaigns, enabling the detailed evaluation of models. Improved numerical methods have resulted in more accurate and efficient dynamical cores in models. Improvements have been made in the parameterizations of microphysical processes, radiation, boundary-layer effects, and turbulence; however, microphysical parameterizations remain a major source of uncertainty in all classes of atmospheric models. In recent years, exponentially increasing computer power has extended cloud-resolving-model integrations from hours to months, the number of computational grid points from less than a thousand to close to ten million. Three-dimensional models are now more prevalent. Much attention is devoted to precipitating cloud systems where the crucial 1-kilometer scales are resolved in horizontal domains as large as 10,000 kilometers in two dimensions, and 1,000 x 1,000 square kilometers in three-dimensions. Cloud models now provide statistical information useful for developing more realistic physically-based parameterizations for climate models and numerical weather prediction models. A review of developments and applications of cloud models in the past, present and future will be presented in

  3. Cloud Distribution Statistics from LITE

    NASA Technical Reports Server (NTRS)

    Winker, David M.

    1998-01-01

    The Lidar In-Space Technology Experiment (LITE) mission has demonstrated the utility of spaceborne lidar in observing multilayer clouds and has provided a dataset showing the distribution of tropospheric clouds and aerosols. These unambiguous observations of the vertical distribution of clouds will allow improved verification of current cloud climatologies and GCM cloud parameterizations. Although there is now great interest in cloud profiling radar, operating in the mm-wave region, for the spacebased observation of cloud heights the results of the LITE mission have shown that satellite lidars can also make significant contributions in this area.

  4. Entrainment, Drizzle, and Cloud Albedo

    NASA Technical Reports Server (NTRS)

    Ackerman, A. S.; Kirkpatrick, J. P.; Stevens, D. E.; Toon, O. B.

    2004-01-01

    Increased aerosol and hence droplet concentrations in polluted clouds are expected to inhibit precipitation and thereby increase cloud water, leading to more reflective clouds that partially offset global warming. Yet polluted clouds are not generally observed to hold more water. Much of the uncertainty regarding the indirect aerosol effect stems from inadequate understanding of such changes in cloud water. Detailed simulations show that the relative humidity of air overlying stratocumulus is a leading factor determining whether cloud water increases or decreases when precipitation is suppressed. When the overlying air is dry, cloud water can decrease as droplet concentrations increase.

  5. Extended field observations of cirrus clouds using a ground-based cloud observing system

    NASA Technical Reports Server (NTRS)

    Ackerman, Thomas P.

    1994-01-01

    The evolution of synoptic-scale dynamics associated with a middle and upper tropospheric cloud event that occurred on 26 November 1991 is examined. The case under consideration occurred during the FIRE CIRRUS-II Intensive Field Observing Period held in Coffeyville, KS during Nov. and Dec., 1991. Using data from the wind profiler demonstration network and a temporally and spatially augmented radiosonde array, emphasis is given to explaining the evolution of the kinematically-derived ageostrophic vertical circulations and correlating the circulation with the forcing of an extensively sampled cloud field. This is facilitated by decomposing the horizontal divergence into its component parts through a natural coordinate representation of the flow. Ageostrophic vertical circulations are inferred and compared to the circulation forcing arising from geostrophic confluence and shearing deformation derived from the Sawyer-Eliassen Equation. It is found that a thermodynamically indirect vertical circulation existed in association with a jet streak exit region. The circulation was displaced to the cyclonic side of the jet axis due to the orientation of the jet exit between a deepening diffluent trough and building ridge. The cloud line formed in the ascending branch of the vertical circulation with the most concentrated cloud development occurring in conjunction with the maximum large-scale vertical motion. The relationship between the large scale dynamics and the parameterization of middle and upper tropospheric clouds in large-scale models is discussed and an example of ice water contents derived from a parameterization forced by the diagnosed vertical motions and observed water vapor contents is presented.

  6. Methanol in dark clouds

    NASA Astrophysics Data System (ADS)

    Friberg, P.; Hjalmarson, A.; Madden, S. C.; Irvine, W. M.

    1988-04-01

    The authors report observations, for the first time, of the 20 - 10A+ and E, 2-1 - 1-1 E, and 10 - 00A+ lines of methanol (CH3OH) in three dark cold clouds, TMC 1, L 134N, and B 335. The CH3OH emission is extended in these clouds and shows a complex velocity structure. Clear indications of non LTE excitation are observed in TMC 1. Estimated column densities are a few×1013cm-2. Although less abundant than formaldehyde (H2CO), methanol is almost an order of magnitude more abundant than acetaldehyde (CH3CHO), in these clouds. Dimethyl ether was searched for in L 134N, to an upper limit of 4×1012cm-2 (3σ). Implications for dark cloud excitation and chemistry are discussed.

  7. Fingerprinting the Clouds

    NASA Astrophysics Data System (ADS)

    Orellana, M. V.; Caballero, J.; Lee, A. M.; Matrai, P. A.; Leck, C.; Madan, A.; Collins, H.

    2012-12-01

    Marine microgels play an important role in regulating ocean-basin-scale biogeochemical dynamics. We have found them in surface waters, in airborne aerosol, fog, and cloud water in the high Arctic (north of 80oN). Microgels dominated the available cloud condensation nuclei number population during the summer season. These microgels have unique physicochemical characteristics and originate from the ice algae and/or phytoplankton in the surface water. We have sequenced the genomic material found in the microgels from the sea surface and cloud waters with next-generation sequencing technology. The sequence analysis and annotation, show a high abundance of proteins of microbial and diatom origin, including a high number of proteins from different taxonomical origin associated with antifreeze functions. Our results have implications not only for cloud droplet activation but also for ice nucleation.

  8. My NASA Data Clouds

    NASA Video Gallery

    This lesson has two activities that help students develop a basic understanding of the relationship between cloud type and the form of precipitation and the relationship between the amount of water...

  9. GEOS-5 Modeled Clouds

    NASA Video Gallery

    This visualization shows clouds from a simulation using the Goddard Earth Observing System Model, Verison 5 (GEOS-5). The global atmospheric simulation covers a period from Feb 3, 2010 through Feb ...

  10. Methanol in dark clouds

    NASA Technical Reports Server (NTRS)

    Friberg, P.; Hjalmarson, A.; Madden, S. C.; Irvine, W. M.

    1988-01-01

    The first observation of methanol in cold dark clouds TMC 1, L 134 N, and B 335 is reported. In all three clouds, the relative abundance of methanol was found to be in the range of 10 to the -9th (i.e., almost an order of magnitude more abundant than acetaldehyde), with no observable variation between the clouds. Methanol emission showed a complex velocity structure; in TMC 1, clear indications of non-LTE were observed. Dimethyl ether was searched for in L 134 N; the upper limit of the column density of dimethyl ether in L 134 N was estimated to be 4 x 10 to the 12th/sq cm, assuming 5 K rotation temperature and LTE. This limit makes the abundance ratio (CH3)2O/CH3OH not higher than 1/5, indicating that dimethyl ether is not overabundant in this dark cloud.

  11. Graph-Based Compression of Dynamic 3D Point Cloud Sequences.

    PubMed

    Thanou, Dorina; Chou, Philip A; Frossard, Pascal

    2016-04-01

    This paper addresses the problem of compression of 3D point cloud sequences that are characterized by moving 3D positions and color attributes. As temporally successive point cloud frames share some similarities, motion estimation is key to effective compression of these sequences. It, however, remains a challenging problem as the point cloud frames have varying numbers of points without explicit correspondence information. We represent the time-varying geometry of these sequences with a set of graphs, and consider 3D positions and color attributes of the point clouds as signals on the vertices of the graphs. We then cast motion estimation as a feature-matching problem between successive graphs. The motion is estimated on a sparse set of representative vertices using new spectral graph wavelet descriptors. A dense motion field is eventually interpolated by solving a graph-based regularization problem. The estimated motion is finally used for removing the temporal redundancy in the predictive coding of the 3D positions and the color characteristics of the point cloud sequences. Experimental results demonstrate that our method is able to accurately estimate the motion between consecutive frames. Moreover, motion estimation is shown to bring a significant improvement in terms of the overall compression performance of the sequence. To the best of our knowledge, this is the first paper that exploits both the spatial correlation inside each frame (through the graph) and the temporal correlation between the frames (through the motion estimation) to compress the color and the geometry of 3D point cloud sequences in an efficient way. PMID:26891486

  12. Exploiting Cloud Radar Doppler Spectra of Mixed-Phase Clouds during ACCEPT Field Experiment to Identify Microphysical Processes

    NASA Astrophysics Data System (ADS)

    Kalesse, H.; Myagkov, A.; Seifert, P.; Buehl, J.

    2015-12-01

    Cloud radar Doppler spectra offer much information about cloud processes. By analyzing millimeter radar Doppler spectra from cloud-top to -base in mixed-phase clouds in which super-cooled liquid-layers are present we try to tell the microphysical evolution story of particles that are present by disentangling the contributions of the solid and liquid particles to the total radar returns. Instead of considering vertical profiles, dynamical effects are taken into account by following the particle population evolution along slanted paths which are caused by horizontal advection of the cloud. The goal is to identify regions in which different microphysical processes such as new particle formation (nucleation), water vapor deposition, aggregation, riming, or sublimation occurr. Cloud radar measurements are supplemented by Doppler lidar and Raman lidar observations as well as observations with MWR, wind profiler, and radio sondes. The presence of super-cooled liquid layers is identified by positive liquid water paths in MWR measurements, the vertical location of liquid layers (in non-raining systems and below lidar extinction) is derived from regions of high-backscatter and low depolarization in Raman lidar observations. In collocated cloud radar measurements, we try to identify cloud phase in the cloud radar Doppler spectrum via location of the Doppler peak(s), the existence of multi-modalities or the spectral skewness. Additionally, within the super-cooled liquid layers, the radar-identified liquid droplets are used as air motion tracer to correct the radar Doppler spectrum for vertical air motion w. These radar-derived estimates of w are validated by independent estimates of w from collocated Doppler lidar measurements. A 35 GHz vertically pointing cloud Doppler radar (METEK MIRA-35) in linear depolarization (LDR) mode is used. Data is from the deployment of the Leipzig Aerosol and Cloud Remote Observations System (LACROS) during the Analysis of the Composition of

  13. Motion coherence affects human perception and pursuit similarly

    NASA Technical Reports Server (NTRS)

    Beutter, B. R.; Stone, L. S.

    2000-01-01

    Pursuit and perception both require accurate information about the motion of objects. Recovering the motion of objects by integrating the motion of their components is a difficult visual task. Successful integration produces coherent global object motion, while a failure to integrate leaves the incoherent local motions of the components unlinked. We compared the ability of perception and pursuit to perform motion integration by measuring direction judgments and the concomitant eye-movement responses to line-figure parallelograms moving behind stationary rectangular apertures. The apertures were constructed such that only the line segments corresponding to the parallelogram's sides were visible; thus, recovering global motion required the integration of the local segment motion. We investigated several potential motion-integration rules by using stimuli with different object, vector-average, and line-segment terminator-motion directions. We used an oculometric decision rule to directly compare direction discrimination for pursuit and perception. For visible apertures, the percept was a coherent object, and both the pursuit and perceptual performance were close to the object-motion prediction. For invisible apertures, the percept was incoherently moving segments, and both the pursuit and perceptual performance were close to the terminator-motion prediction. Furthermore, both psychometric and oculometric direction thresholds were much higher for invisible apertures than for visible apertures. We constructed a model in which both perception and pursuit are driven by a shared motion-processing stage, with perception having an additional input from an independent static-processing stage. Model simulations were consistent with our perceptual and oculomotor data. Based on these results, we propose the use of pursuit as an objective and continuous measure of perceptual coherence. Our results support the view that pursuit and perception share a common motion

  14. Cloud Inhomogeneity from MODIS

    NASA Technical Reports Server (NTRS)

    Oreopoulos, Lazaros; Cahalan, Robert F.

    2004-01-01

    Two full months (July 2003 and January 2004) of MODIS Atmosphere Level-3 data from the Terra and Aqua satellites are analyzed in order to characterize the horizontal variability of cloud optical thickness and water path at global scales. Various options to derive cloud variability parameters are discussed. The climatology of cloud inhomogeneity is built by first calculating daily parameter values at spatial scales of l degree x 1 degree, and then at zonal and global scales, followed by averaging over monthly time scales. Geographical, diurnal, and seasonal changes of inhomogeneity parameters are examined separately for the two cloud phases, and separately over land and ocean. We find that cloud inhomogeneity is weaker in summer than in winter, weaker over land than ocean for liquid clouds, weaker for local morning than local afternoon, about the same for liquid and ice clouds on a global scale, but with wider probability distribution functions (PDFs) and larger latitudinal variations for ice, and relatively insensitive to whether water path or optical thickness products are used. Typical mean values at hemispheric and global scales of the inhomogeneity parameter nu (roughly the mean over the standard deviation of water path or optical thickness), range from approximately 2.5 to 3, while for the inhomogeneity parameter chi (the ratio of the logarithmic to linear mean) from approximately 0.7 to 0.8. Values of chi for zonal averages can occasionally fall below 0.6 and for individual gridpoints below 0.5. Our results demonstrate that MODIS is capable of revealing significant fluctuations in cloud horizontal inhomogenity and stress the need to model their global radiative effect in future studies.

  15. Mesospheric cloud formations

    NASA Technical Reports Server (NTRS)

    Forbes, J. M.

    1980-01-01

    Formation of mesospheric clouds as a result of deposition of large amounts of H2O by the heavy lift launch vehicle (HLLV) of the solar power satellite system is discussed. The conditions which must be met in order to form and maintain clouds near the mesopause are described. The frequency and magnitude of H2O injections from the HLLV rocket exhaust are considered.

  16. Marine Cloud Brightening

    SciTech Connect

    Latham, John; Bower, Keith; Choularton, Tom; Coe, H.; Connolly, P.; Cooper, Gary; Craft, Tim; Foster, Jack; Gadian, Alan; Galbraith, Lee; Iacovides, Hector; Johnston, David; Launder, Brian; Leslie, Brian; Meyer, John; Neukermans, Armand; Ormond, Bob; Parkes, Ben; Rasch, Philip J.; Rush, John; Salter, Stephen; Stevenson, Tom; Wang, Hailong; Wang, Qin; Wood, Robert

    2012-09-07

    The idea behind the marine cloud-brightening (MCB) geoengineering technique is that seeding marine stratocumulus clouds with copious quantities of roughly monodisperse sub-micrometre sea water particles might significantly enhance the cloud droplet number concentration, and thereby the cloud albedo and possibly longevity. This would produce a cooling, which general circulation model (GCM) computations suggest could - subject to satisfactory resolution of technical and scientific problems identified herein - have the capacity to balance global warming up to the carbon dioxide-doubling point. We describe herein an account of our recent research on a number of critical issues associated with MCB. This involves (i) GCM studies, which are our primary tools for evaluating globally the effectiveness of MCB, and assessing its climate impacts on rainfall amounts and distribution, and also polar sea-ice cover and thickness; (ii) high-resolution modelling of the effects of seeding on marine stratocumulus, which are required to understand the complex array of interacting processes involved in cloud brightening; (iii) microphysical modelling sensitivity studies, examining the influence of seeding amount, seedparticle salt-mass, air-mass characteristics, updraught speed and other parameters on cloud-albedo change; (iv) sea water spray-production techniques; (v) computational fluid dynamics studies of possible large-scale periodicities in Flettner rotors; and (vi) the planning of a three-stage limited-area field research experiment, with the primary objectives of technology testing and determining to what extent, if any, cloud albedo might be enhanced by seeding marine stratocumulus clouds on a spatial scale of around 100 km. We stress that there would be no justification for deployment of MCB unless it was clearly established that no significant adverse consequences would result. There would also need to be an international agreement firmly in favour of such action.

  17. Human action recognition using motion energy template

    NASA Astrophysics Data System (ADS)

    Shao, Yanhua; Guo, Yongcai; Gao, Chao

    2015-06-01

    Human action recognition is an active and interesting research topic in computer vision and pattern recognition field that is widely used in the real world. We proposed an approach for human activity analysis based on motion energy template (MET), a new high-level representation of video. The main idea for the MET model is that human actions could be expressed as the composition of motion energy acquired in a three-dimensional (3-D) space-time volume by using a filter bank. The motion energies were directly computed from raw video sequences, thus some problems, such as object location and segmentation, etc., are definitely avoided. Another important competitive merit of this MET method is its insensitivity to gender, hair, and clothing. We extract MET features by using the Bhattacharyya coefficient to measure the motion energy similarity between the action template video and the tested video, and then the 3-D max-pooling. Using these features as input to the support vector machine, extensive experiments on two benchmark datasets, Weizmann and KTH, were carried out. Compared with other state-of-the-art approaches, such as variation energy image, dynamic templates and local motion pattern descriptors, the experimental results demonstrate that our MET model is competitive and promising.

  18. INTERNAL PROPER MOTIONS IN THE ESKIMO NEBULA

    SciTech Connect

    García-Díaz, Ma. T.; Gutiérrez, L.; Steffen, W.; López, J. A.; Beckman, J. E-mail: leonel@astro.unam.mx E-mail: jal@astro.unam.mx

    2015-01-10

    We present measurements of internal proper motions at more than 500 positions of NGC 2392, the Eskimo Nebula, based on images acquired with WFPC2 on board the Hubble Space Telescope at two epochs separated by 7.695 yr. Comparisons of the two observations clearly show the expansion of the nebula. We measured the amplitude and direction of the motion of local structures in the nebula by determining their relative shift during that interval. In order to assess the potential uncertainties in the determination of proper motions in this object, in general, the measurements were performed using two different methods, used previously in the literature. We compare the results from the two methods, and to perform the scientific analysis of the results we choose one, the cross-correlation method, because it is more reliable. We go on to perform a ''criss-cross'' mapping analysis on the proper motion vectors, which helps in the interpretation of the velocity pattern. By combining our results of the proper motions with radial velocity measurements obtained from high resolution spectroscopic observations, and employing an existing 3D model, we estimate the distance to the nebula to be 1.3 kpc.

  19. Image sequence enhancements based on the normal component of image motion

    NASA Astrophysics Data System (ADS)

    Davis, L. S.; Hie, H. C.; Rosenfeld, A.

    1982-07-01

    In a recent paper, Huang and Hsu describe an enhancement algorithm for time-varying images. This algorithm achieves the type of enhancement that one would obtain from averaging multiple images of a static scene by using motion vectors computed from the sequence to establish the correspondence between pixels in successive frames. The purpose of this note is to demonstrate how and why it is often sufficient to consider only the normal components of the motion vectors, i.e., the component in the gradient direction, to compute such enhancements. There is a computational advantage to using only the normal component, since it is directly measurable from the image sequence by combining the space and time derivatives of image intensity, while computing the actual motion vectors ordinarily requires some spatial integration of the normal components or the application of a local correlation procedure. Furthermore, in order to compute the motion vectors one must make some assumption about the local image motion (for example, that the image motion is a two-dimensional translation); when this assumption is incorrect, the computed motion vectors will be in error.

  20. A hillock and cloud model for faculae

    NASA Technical Reports Server (NTRS)

    Schatten, Kenneth H.; Mayr, Hans G.; Omidvar, Kazem; Maier, Eugene

    1986-01-01

    A hillock model is used here to explain facular contrasts, allowing faculae to emit more energy than the surrounding unmagnetized photosphere. For downflows, horizontal motions converge near the photosphere and many fibril flux tubes are drawn together to form a large dark area, the sunspot. For upflows, the motions diverge near the photosphere and fibril flux tubes are dispersed over a larger area associated with faculae. The upflows transport material and energy, resulting in hotter than normal temperatures, which in turn cause the gas to expand compared with its surroundings. Buoyancy thus causes a 'network' of patchy hillocks, clouds, or geysers to form which allows the sun to reradiate the energy deficit associated with sunspots by locally increasing the effective surface area of the sun beyond that of a sphere. The consequences of this model for the physical form of the facular manifestation, the appearance of faculae from earth, and the 'energy balance' in active regions are addressed.

  1. Activity recognition using a mixture of vector fields.

    PubMed

    Nascimento, Jacinto C; Figueiredo, Mário A T; Marques, Jorge S

    2013-05-01

    The analysis of moving objects in image sequences (video) has been one of the major themes in computer vision. In this paper, we focus on video-surveillance tasks; more specifically, we consider pedestrian trajectories and propose modeling them through a small set of motion/vector fields together with a space-varying switching mechanism. Despite the diversity of motion patterns that can occur in a given scene, we show that it is often possible to find a relatively small number of typical behaviors, and model each of these behaviors by a "simple" motion field. We increase the expressiveness of the formulation by allowing the trajectories to switch from one motion field to another, in a space-dependent manner. We present an expectation-maximization algorithm to learn all the parameters of the model, and apply it to trajectory classification tasks. Experiments with both synthetic and real data support the claims about the performance of the proposed approach. PMID:23193235

  2. Interstellar Cloud Collisions

    NASA Astrophysics Data System (ADS)

    Lattanzio, J. C.; Monaghan, J. J.; Pongracic, H.; Schwarz, M. P.

    1985-07-01

    We describe the results of a three-dimensional numerical simulation of isothermal interstellar clouds in the absence of magnetic fields. A wide variety of high and low Mach number, head-on and off-centre collisions of clouds with mass ratios 1, 2.5, 5.0 and 10.1 have been studied. The results show that a necessary, but not sufficient, condition for the gravitational instability of a substantial fraction of the matter is that the initial clouds should be either marginally stable or unstable according to the usual Jeans criterion. The collisions, in general, do not result in one or more clouds. Instead we find, in most cases, that the matter disperses in an irregular way. The calculations therefore suggest that if the initial state of the interstellar medium is one of cool dense clouds in a hotter more tenuous background, collisions will rapidly mix the medium rather than produce a steady-state spectrum of cool clouds.

  3. FIRE Arctic Clouds Experiment

    NASA Technical Reports Server (NTRS)

    Curry, J. A.; Hobbs, P. V.; King, M. D.; Randall, D. A.; Minnis, P.; Issac, G. A.; Pinto, J. O.; Uttal, T.; Bucholtz, A.; Cripe, D. G.; Gerber, H.; Fairall, C. W.; Garrett, T. J.; Hudson, J.; Intrieri, J. M.; Jakob, C.; Jensen, T.; Lawson, P.; Marcotte, D.; Nguyen, L.

    1998-01-01

    An overview is given of the First ISCCP Regional Experiment (FIRE) Arctic Clouds Experiment that was conducted in the Arctic during April through July, 1998. The principal goal of the field experiment was to gather the data needed to examine the impact of arctic clouds on the radiation exchange between the surface, atmosphere, and space, and to study how the surface influences the evolution of boundary layer clouds. The observations will be used to evaluate and improve climate model parameterizations of cloud and radiation processes, satellite remote sensing of cloud and surface characteristics, and understanding of cloud-radiation feedbacks in the Arctic. The experiment utilized four research aircraft that flew over surface-based observational sites in the Arctic Ocean and Barrow, Alaska. In this paper we describe the programmatic and science objectives of the project, the experimental design (including research platforms and instrumentation), conditions that were encountered during the field experiment, and some highlights of preliminary observations, modelling, and satellite remote sensing studies.

  4. A cloud physics radiometer

    NASA Technical Reports Server (NTRS)

    Kyle, H. L.; Curran, R. J.; Barnes, W. L.; Escoe, D.

    1978-01-01

    The paper describes the design features and capabilities of a seven-channel cloud physics radiometer (CPR) for remote sensing of cloud properties. The CPR channel characteristics and functions are tabulated and diagrammed. Each of the first three channels utilizes a photo-multipler detector, with the high-voltage power supply integrated with the tube into a single unit. In operation a heater is used to keep the optics temperature at or above 273 K and this temperature is constantly monitored. The last four channel detectors and filters are all cooled to the temperature of liquid nitrogen. The inclined scanning mirror rotates at a rate of 3.48 rps. Registration pulses are triggered and recorded as the mirror enters and leaves the + or -45 deg earth observation region. The ice-cloud, water cloud, snow discriminator detector has worked quite well in general. Interesting radiometer data have been obtained and their analysis is under way. The combination of the CPR and the Cloud Lidar System will make possible sophisticated remote sensing cloud studies.

  5. Molecules in interstellar clouds

    NASA Astrophysics Data System (ADS)

    Irvine, W. M.; Hjalmarson, A.; Rydbeck, O. E. H.

    The physical conditions and chemical compositions of the gas in interstellar clouds are reviewed in light of the importance of interstellar clouds for star formation and the origin of life. The Orion A region is discussed as an example of a giant molecular cloud where massive stars are being formed, and it is pointed out that conditions in the core of the cloud, with a kinetic temperature of about 75 K and a density of 100,000-1,000,000 molecules/cu cm, may support gas phase ion-molecule chemistry. The Taurus Molecular Clouds are then considered as examples of cold, dark, relatively dense interstellar clouds which may be the birthplaces of solar-type stars and which have been found to contain the heaviest interstellar molecules yet discovered. The molecular species identified in each of these regions are tabulated, including such building blocks of biological monomers as H2O, NH3, H2CO, CO, H2S, CH3CN and H2, and more complex species such as HCOOCH3 and CH3CH2CN.

  6. Molecular clouds toward the super star cluster NGC 3603; possible evidence for a cloud-cloud collision in triggering the cluster formation

    SciTech Connect

    Fukui, Y.; Ohama, A.; Hanaoka, N.; Furukawa, N.; Torii, K.; Hasegawa, K.; Fukuda, T.; Soga, S.; Moribe, N.; Kuroda, Y.; Hayakawa, T.; Kuwahara, T.; Yamamoto, H.; Okuda, T.; Dawson, J. R.; Mizuno, N.; Kawamura, A.; Onishi, T.; Maezawa, H.; Mizuno, A.

    2014-01-01

    We present new large field observations of molecular clouds with NANTEN2 toward the super star cluster NGC 3603 in the transitions {sup 12}CO(J = 2-1, J = 1-0) and {sup 13}CO(J = 2-1, J = 1-0). We suggest that two molecular clouds at 13 km s{sup –1} and 28 km s{sup –1} are associated with NGC 3603 as evidenced by higher temperatures toward the H II region, as well as morphological correspondence. The mass of the clouds is too small to gravitationally bind them, given their relative motion of ∼20 km s{sup –1}. We suggest that the two clouds collided with each other 1 Myr ago to trigger the formation of the super star cluster. This scenario is able to explain the origin of the highest mass stellar population in the cluster, which is as young as 1 Myr and is segregated within the central sub-pc of the cluster. This is the second super star cluster along with Westerlund 2 where formation may have been triggered by a cloud-cloud collision.

  7. Rigid Body Motion in Stereo 3D Simulation

    ERIC Educational Resources Information Center

    Zabunov, Svetoslav

    2010-01-01

    This paper addresses the difficulties experienced by first-grade students studying rigid body motion at Sofia University. Most quantities describing the rigid body are in relations that the students find hard to visualize and understand. They also lose the notion of cause-result relations between vector quantities, such as the relation between…

  8. Motion of Air Bubbles in Water Subjected to Microgravity Accelerations

    NASA Technical Reports Server (NTRS)

    DeLombard, Richard; Kelly, Eric M.; Hrovat, Kenneth; Nelson, Emily S.; Pettit, Donald R.

    2006-01-01

    The International Space Station (ISS) serves as a platform for microgravity research for the foreseeable future. A microgravity environment is one in which the effects of gravity are drastically reduced which then allows physical experiments to be conducted without the over powering effects of gravity. During his 6-month stay on the ISS, astronaut Donald R. Pettit performed many informal/impromptu science experiments with available equipment. One such experiment focused on the motion of air bubbles in a rectangular container nearly filled with de-ionized water. Bubbles were introduced by shaking and then the container was secured in place for several hours while motion of the bubbles was recorded using time-lapse photography. This paper shows correlation between bubble motion and quasi-steady acceleration levels during one such experiment operation. The quasi-steady acceleration vectors were measured by the Microgravity Acceleration Measurement System (MAMS). Essentially linear motion was observed in the condition considered here. Dr. Pettit also created other conditions which produced linear and circulating motion, which are the subjects of further study. Initial observations of this bubble motion agree with calculations from many microgravity physical science experiments conducted on shuttle microgravity science missions. Many crystal-growth furnaces involve heavy metals and high temperatures in which undesired acceleration-driven convection during solidification can adversely affect the crystal. Presented in this paper will be results showing correlation between bubble motion and the quasi-steady acceleration vector.

  9. Motion of Air Bubbles in Water Subjected to Microgravity Accelerations

    NASA Technical Reports Server (NTRS)

    DeLombard, Richard; Kelly, Eric M.; Hrovar, Kenneth; Nelson, Emily S.; Pettit, Donald R.

    2004-01-01

    The International Space Station (ISS) serves as a platform for microgravity research for the foreseeable future. A microgravity environment is one in which the effects of gravity are drastically reduced which then allows physical experiments to be conducted without the overpowering effects of gravity. During his six month stay on the ISS, astronaut Donald R Pettit performed many informal/impromptu science experiments with available equipment. One such experiment focused on the motion of air bubbles in a rectangular container nearly filled with de-ionized water. Bubbles were introduced by shaking and the container was secured in place for several hours while motion of the bubbles were recorded using time-lapse photography. This paper shows correlation between bubble motion and quasi-steady acceleration levels during one such experiment operation. The quasi-steady acceleration vectors were measured by the Microgravity Acceleration Measurement System. Essentially linear motion was observed in the condition considered here. Dr. Pettit also created other conditions which produced linear and circulating motion, which are the subjects of further study. Initial observations of this bubble motion agree with calculations from many microgravity physical science experiments conducted on Shuttle microgravity science missions. Many crystal-growth furnaces involve heavy metals and high temperatures in which undesired acceleration-driven convection during solidification can adversely affect the crystal. Presented in this paper will be results showing correlation between bubble motion and the quasi-steady acceleration vector.

  10. Improving optical bench radius measurements using stage error motion data

    SciTech Connect

    Schmitz, Tony L.; Gardner, Neil; Vaughn, Matthew; Medicus, Kate; Davies, Angela

    2008-12-20

    We describe the application of a vector-based radius approach to optical bench radius measurements in the presence of imperfect stage motions. In this approach, the radius is defined using a vector equation and homogeneous transformation matrix formulism. This is in contrast to the typical technique, where the displacement between the confocal and cat's eye null positions alone is used to determine the test optic radius. An important aspect of the vector-based radius definition is the intrinsic correction for measurement biases, such as straightness errors in the stage motion and cosine misalignment between the stage and displacement gauge axis, which lead to an artificially small radius value if the traditional approach is employed. Measurement techniques and results are provided for the stage error motions, which are then combined with the setup geometry through the analysis to determine the radius of curvature for a spherical artifact. Comparisons are shown between the new vector-based radius calculation, traditional radius computation, and a low uncertainty mechanical measurement. Additionally, the measurement uncertainty for the vector-based approach is determined using Monte Carlo simulation and compared to experimental results.

  11. Preloadable vector sensitive latch

    NASA Technical Reports Server (NTRS)

    Acres, William R. (Inventor)

    1987-01-01

    A preloadable vector-sensitive latch which automatically releases when the force vector from a latch memebr reaches a specified release angle is presented. In addition, it contains means to remove clearance between the latched members and to preload the latch to prevent separation at angles less than the specified release angle. The latch comprises a triangular main link, a free link connected between a first corner of the main link and a yoke member, a housing, and an actuator connected between the yoke member and the housing. A return spring bias means connects the main link to a portion of the housing. A second corner of the main link is slidably and pivotally connected to the housing via a slot in a web portion of the housing. The latch housing has a rigid docking ring alignable with a mating locking ring which is engageable by a locking roller journalled on the third corner of the triangular main link.

  12. Motion Tracking System

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Integrated Sensors, Inc. (ISI), under NASA contract, developed a sensor system for controlling robot vehicles. This technology would enable a robot supply vehicle to automatically dock with Earth-orbiting satellites or the International Space Station. During the docking phase the ISI-developed sensor must sense the satellite's relative motion, then spin so the robot vehicle can adjust its motion to align with the satellite and slowly close until docking is completed. ISI used the sensing/tracking technology as the basis of its OPAD system, which simultaneously tracks an object's movement in six degrees of freedom. Applications include human limb motion analysis, assembly line position analysis and auto crash dummy motion analysis. The NASA technology is also the basis for Motion Analysis Workstation software, a package to simplify the video motion analysis process.

  13. Kontur: Observations of cloud streets and open cellular structures

    NASA Astrophysics Data System (ADS)

    Brümmer, B.; Bakan, S.; Hinzpeter, H.

    1985-08-01

    In September and October 1981 the experiment KonTur (Convection and turbulence) was conducted over the North Sea. Its objectives were to investigate organized convective patterns, like cloud streets (boundary layer rolls) and cellular cloud structures. Two aircraft (British Hercules C-130 and German Falcon 20) performed detailed measurements within these patterns. Several cases of cloud streets and open cells were observed. Boundary layer rolls appear to be connected with an inflection point in the cross-roll wind component. The aspect ratio of the rolls (wavelength versus depth) is between three and four in accordance with other observations and linear stability analysis. Four scales of motion are involved: the mean flow, the roll circulation, individual clouds and turbulence. The vertical transport are dominated at lower levels by turbulence and at higher levels by roll-scale motions. Open cellular cloud structures are connected with large air-sea temperature differences due to cold air outbreaks from the northwest. The aspect ratio of the cells is of the order of 10. The bulk contribution to the total transport of heat and momentum originates from the cloudy walls of the cells. A vertical cross section through a composite open cell is presented.

  14. FORMATION OF MASSIVE MOLECULAR CLOUD CORES BY CLOUD-CLOUD COLLISION

    SciTech Connect

    Inoue, Tsuyoshi; Fukui, Yasuo

    2013-09-10

    Recent observations of molecular clouds around rich massive star clusters including NGC 3603, Westerlund 2, and M20 revealed that the formation of massive stars could be triggered by a cloud-cloud collision. By using three-dimensional, isothermal, magnetohydrodynamics simulations with the effect of self-gravity, we demonstrate that massive, gravitationally unstable, molecular cloud cores are formed behind the strong shock waves induced by cloud-cloud collision. We find that the massive molecular cloud cores have large effective Jeans mass owing to the enhancement of the magnetic field strength by shock compression and turbulence in the compressed layer. Our results predict that massive molecular cloud cores formed by the cloud-cloud collision are filamentary and threaded by magnetic fields perpendicular to the filament.

  15. Vector Magnetograph Design

    NASA Technical Reports Server (NTRS)

    Chipman, Russell A.

    1996-01-01

    This report covers work performed during the period of November 1994 through March 1996 on the design of a Space-borne Solar Vector Magnetograph. This work has been performed as part of a design team under the supervision of Dr. Mona Hagyard and Dr. Alan Gary of the Space Science Laboratory. Many tasks were performed and this report documents the results from some of those tasks, each contained in the corresponding appendix. Appendices are organized in chronological order.

  16. Some experiences with Krylov vectors and Lanczos vectors

    NASA Technical Reports Server (NTRS)

    Craig, Roy R., Jr.; Su, Tzu-Jeng; Kim, Hyoung M.

    1993-01-01

    This paper illustrates the use of Krylov vectors and Lanczos vectors for reduced-order modeling in structural dynamics and for control of flexible structures. Krylov vectors and Lanczos vectors are defined and illustrated, and several applications that have been under study at The University of Texas at Austin are reviewed: model reduction for undamped structural dynamics systems, component mode synthesis using Krylov vectors, model reduction of damped structural dynamics systems, and one-sided and two-sided unsymmetric block-Lanczos model-reduction algorithms.

  17. First observations of tracking clouds using scanning ARM cloud radars

    SciTech Connect

    Borque, Paloma; Giangrande, Scott; Kollias, Pavlos

    2014-12-01

    Tracking clouds using scanning cloud radars can help to document the temporal evolution of cloud properties well before large drop formation (‘‘first echo’’). These measurements complement cloud and precipitation tracking using geostationary satellites and weather radars. Here, two-dimensional (2-D) Along-Wind Range Height Indicator (AW-RHI) observations of a population of shallow cumuli (with and without precipitation) from the 35-GHz scanning ARM cloud radar (SACR) at the DOE Atmospheric Radiation Measurements (ARM) program Southern Great Plains (SGP) site are presented. Observations from the ARM SGP network of scanning precipitation radars are used to provide the larger scale context of the cloud field and to highlight the advantages of the SACR to detect the numerous, small, non-precipitating cloud elements. A new Cloud Identification and Tracking Algorithm (CITA) is developed to track cloud elements. In CITA, a cloud element is identified as a region having a contiguous set of pixels exceeding a preset reflectivity and size threshold. The high temporal resolution of the SACR 2-D observations (30 sec) allows for an area superposition criteria algorithm to match cloud elements at consecutive times. Following CITA, the temporal evolution of cloud element properties (number, size, and maximum reflectivity) is presented. The vast majority of the designated elements during this cumulus event were short-lived non-precipitating clouds having an apparent life cycle shorter than 15 minutes. The advantages and disadvantages of cloud tracking using an SACR are discussed.

  18. Measuring the efficiency of ice formation in mixed-phase clouds over Europe with Cloudnet

    NASA Astrophysics Data System (ADS)

    Bühl, Johannes; Engelmann, Ronny; Ansmann, Albert; Patric, Seifert

    2016-04-01

    Mixed-phase clouds play an important role in current weather and climate research. The complex interaction between aerosols, clouds and dynamics taking place within these clouds is still not understood. The unknown impact of ice formation on cloud lifetime and precipitation evolution introduces large uncertainties into numeric weather prediction and climate projections. In the framework of the BACCHUS project, we have evaluated combined remote sensing data gathered at different European Cloudnet sites (Leipzig, Lindenberg, Potenza and Mace-Head) to study the relation between ice and liquid water in mixed-phase cloud layers. In this way, we can quantify the efficiency of ice production within these clouds. The study also allows contrasting marine (Potenza and Mace-Head) and continental sites (Leipzig and Lindenberg). We derive liquid and ice water content together with vertical motions of ice particles falling through cloud base. The ice mass flux is quantified by combining measurements of ice water content and particle fall velocity. The efficiency of heterogeneous ice formation and its impact on cloud lifetime is estimated for different cloud-top temperatures by relating the ice mass flux and the liquid water content at cloud top. Cloud radar measurements of polarization and fall velocity yield, that ice crystals formed in cloud layers with a geometrical thickness of less than 350 m are mostly pristine when they fall out of the cloud. A difference of four orders of magnitude in ice formation efficiency in mixed-phase cloud layers is found over the cloud-top-temperature range from -40 to 0 °C.

  19. Isomap based supporting vector machine

    NASA Astrophysics Data System (ADS)

    Liang, W. N.

    2015-12-01

    This research presents a new isomap based supporting vector machine method. Isomap is a dimension reduction method which is able to analyze nonlinear relationship of data on manifolds. Accordingly, support vector machine is established on the isomap manifold to classify given and predict unknown data. A case study of the isomap based supporting vector machine for environmental planning problems is conducted.

  20. Semicircular canals as a primary etiological factor in motion sickness.

    NASA Technical Reports Server (NTRS)

    Miller, E. F., II; Graybiel, A.

    1972-01-01

    Data are presented which support the view that the semicircular canals of humans can act as the essential factor for the production of motion sickness and the evocation of symptoms characteristic of this malady in the absence of 'motion.' Quantitative grading of acute symptoms demonstrated that motion sickness can be evoked by stimuli which are adequately provocative and unique for the canals. These results are compared with those of two provocative rotational tests that introduce Coriolis (cross-coupled angular acceleration) forces or generate a rotating linear acceleration vector. Wide interindividual differences but only slight intraindividual differences among the six provocative test conditions are revealed, indicating that individuals usually possess an overall susceptibility to motion which is relatively independent of its type. The fact that typical symptoms of motion sickness were also produced by bithermal irrigation of several subjects who represented a wide range of susceptibility adds to the evidence that semicircular canals can act as the primary etiological factor in this malady.

  1. Anisotropic responses to motion toward and away from the eye

    NASA Technical Reports Server (NTRS)

    Perrone, John A.

    1986-01-01

    When a rigid object moves toward the eye, it is usually perceived as being rigid. However, in the case of motion away from the eye, the motion and structure of the object are perceived nonveridically, with the percept tending to reflect the nonrigid transformations that are present in the retinal image. This difference in response to motion to and from the observer was quantified in an experiment using wire-frame computer-generated boxes which moved toward and away from the eye. Two theoretical systems are developed by which uniform three-dimensional velocity can be recovered from an expansion pattern of nonuniform velocity vectors. It is proposed that the human visual system uses two similar systems for processing motion in depth. The mechanism used for motion away from the eye produces perceptual errors because it is not suited to objects with a depth component.

  2. The Personal Motion Platform

    NASA Technical Reports Server (NTRS)

    Park, Brian Vandellyn

    1993-01-01

    The Neutral Body Posture experienced in microgravity creates a biomechanical equilibrium by enabling the internal forces within the body to find their own balance. A patented reclining chair based on this posture provides a minimal stress environment for interfacing with computer systems for extended periods. When the chair is mounted on a 3 or 6 axis motion platform, a generic motion simulator for simulated digital environments is created. The Personal Motion Platform provides motional feedback to the occupant in synchronization with their movements inside the digital world which enhances the simulation experience. Existing HMD based simulation systems can be integrated to the turnkey system. Future developments are discussed.

  3. Hubble Tracks Clouds on Uranus

    NASA Technical Reports Server (NTRS)

    1997-01-01

    almost as large as continents on Earth, such as Europe. Another cloud (which barely can be seen) rotated along the path shown by the black arrow. It is located at lower altitudes, as indicated by its green color.

    The rings of Uranus are extremely faint in visible light but quite prominent in the near infrared. The brightest ring, the epsilon ring, has a variable width around its circumference. Its widest and thus brightest part is at the top in this image. Two fainter, inner rings are visible next to the epsilon ring.

    Eight of the 10 small Uranian satellites, discovered by Voyager 2, can be seen in both images. Their sizes range from about 25 miles (40 kilometers) for Bianca to 100 miles (150 kilometers) for Puck. The smallest of these satellites have not been detected since the departure of Voyager 2 from Uranus in 1986. These eight satellites revolve around Uranus in less than a day. The inner ones are faster than the outer ones. Their motion in the 90 minutes between both images is marked in the right panel. The area outside the rings was slightly enhanced in brightness to improve the visibility of these faint satellites.

    The Wide Field/Planetary Camera 2 was developed by the Jet Propulsion Laboratory and managed by the Goddard Spaced Flight Center for NASA's Office of Space Science.

    This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http://oposite.stsci.edu/pubinfo/

  4. HUBBLE TRACKS CLOUDS ON URANUS

    NASA Technical Reports Server (NTRS)

    2002-01-01

    large as continents on Earth, such as Europe. Another cloud (which barely can be seen) rotated along the path shown by the black arrow. It is located at lower altitudes, as indicated by its green color. The rings of Uranus are extremely faint in visible light but quite prominent in the near infrared. The brightest ring, the epsilon ring, has a variable width around its circumference. Its widest and thus brightest part is at the top in this image. Two fainter, inner rings are visible next to the epsilon ring. Eight of the 10 small Uranian satellites, discovered by Voyager 2, can be seen in both images. Their sizes range from about 25 miles (40 kilometers) for Bianca to 100 miles (150 kilometers) for Puck. The smallest of these satellites have not been detected since the departure of Voyager 2 from Uranus in 1986. These eight satellites revolve around Uranus in less than a day. The inner ones are faster than the outer ones. Their motion in the 90 minutes between both images is marked in the right panel. The area outside the rings was slightly enhanced in brightness to improve the visibility of these faint satellites. Credits: Erich Karkoschka (University of Arizona), and NASA.

  5. Cloud Structure Anomalies Over the Tropical Pacific During the 1997/98 El Nino

    NASA Technical Reports Server (NTRS)

    Cess, Robert D.; Zhang, Minghua; Wang, Pi-Huan; Wielicki, Bruce A.

    2001-01-01

    Satellite measurements of both cloud vertical structure and cloud-radiative forcing have been used to show that during the strong 1997/98 El Nino there was a substantial change in cloud vertical structure over the tropical Pacific Ocean. Relative to normal years, cloud altitudes were lower in the western portion of the Pacific and higher in the eastern portion. The reason for these redistributions was a collapse of the Walker circulation and enhanced large-scale upward motion over the eastern Pacific, both caused by the lack of a zonal sea surface temperature gradient during El Nino. It is proposed that these cloud structure changes, which significantly impact satellite measurements of the tropical Pacific's radiation budget, would serve as one useful means of testing cloud-climate interactions in climate models.

  6. Diagnosing Pressure in Molecular Clouds through Observations and Simulations

    NASA Astrophysics Data System (ADS)

    Faesi, Christopher; Offner, S.; Goodman, A. A.; Bisbas, T.

    2014-01-01

    Pressure plays a key role in the dynamics of molecular clouds, the birthplaces of stars. Internally, pressure acts against gravity, resisting global collapse and helping explain the overall low star formation efficiencies observed. Externally, the pressure of the ambient lower-density interstellar medium (ISM), in which molecular clouds form, may help to promote cloud stability over timescales long enough for star formation to occur. This basic picture is complicated by several factors. For one, the internal structure of molecular clouds is extremely complex. Turbulent motions, which are supersonic on all but the smallest scales within clouds, promote support globally, but can also create shocks, leading to intricate substructure in a cloud’s density and velocity fields. Furthermore, the boundary of a cloud (on which external pressure presumably acts) is difficult to concretely define, as there is in reality a relatively smooth transition from the more diffuse, warm, atomic ISM to the dense, cold, molecule-dominated cloud itself. Observational diagnostics of pressure are scarce, as they require simultaneous measurement of both gas motions and density. Moreover, assessing the role of pressure in detail within clouds is contingent on knowledge of the cloud’s internal hierarchy. We present a new diagnostic probe of pressure as a function of scale within molecular clouds. We employ 13CO molecular line data from the COMPLETE survey to decompose a molecular cloud into its hierarchical substructure through the use of dendrogram analysis. We take the “kinetic pressure” in the gas to be P=ρσv2, where ρ is the volume density derived from molecular line intensity and simple geometric assumptions, and σv is the velocity dispersion computed from spectral linewidths. Specifically, we calculate the kinetic pressure within and at the interface between each nested structure in the dendrogram. We compare observational results on the Perseus molecular cloud with analysis

  7. Biview learning for human posture segmentation from 3D points cloud.

    PubMed

    Qiao, Maoying; Cheng, Jun; Bian, Wei; Tao, Dacheng

    2014-01-01

    Posture segmentation plays an essential role in human motion analysis. The state-of-the-art method extracts sufficiently high-dimensional features from 3D depth images for each 3D point and learns an efficient body part classifier. However, high-dimensional features are memory-consuming and difficult to handle on large-scale training dataset. In this paper, we propose an efficient two-stage dimension reduction scheme, termed biview learning, to encode two independent views which are depth-difference features (DDF) and relative position features (RPF). Biview learning explores the complementary property of DDF and RPF, and uses two stages to learn a compact yet comprehensive low-dimensional feature space for posture segmentation. In the first stage, discriminative locality alignment (DLA) is applied to the high-dimensional DDF to learn a discriminative low-dimensional representation. In the second stage, canonical correlation analysis (CCA) is used to explore the complementary property of RPF and the dimensionality reduced DDF. Finally, we train a support vector machine (SVM) over the output of CCA. We carefully validate the effectiveness of DLA and CCA utilized in the two-stage scheme on our 3D human points cloud dataset. Experimental results show that the proposed biview learning scheme significantly outperforms the state-of-the-art method for human posture segmentation. PMID:24465721

  8. The collective gyration of a heavy ion cloud in a magnetized plasma

    NASA Technical Reports Server (NTRS)

    Brenning, N.; Swenson, C.; Kelley, M. C.; Providakes, J.; Torbert, R.

    1990-01-01

    In both the ionospheric barium injection experiments CRIT 1 and CRIT 2, a long duration oscillation was seen with a frequency close to the gyro frequency of barium and a time duration of about one second. A model for the phenomena which was proposed for the CRIT 1 experiment is compared to the results from CRIT 2 which made a much more complete set of measurements. The model follows the motion of a low Beta ion cloud through a larger ambient plasma. The internal field of the model is close to antiparallel to the injection direction v sub i but slightly tilted towards the self polarization direction E sub p = -V sub i by B. As the ions move across the magnetic field, the space charge is continuously neutralized by magnetic field aligned electron currents from the ambient ionosphere, drawn by the divergence in the perpendicular electric field. These currents give a perturbation of the magnetic field related to the electric field perturbation by Delta E/Delta B approximately equal to V sub A. The model predictions agree quite well with the observed vector directions, field strengths, and decay times of the electric and magnetic fields in CRIT 2. The possibility to extend the model to the active region, where the ions are produces in this type of self-ionizing injection experiments, is discussed.

  9. A GALACTIC ORIGIN FOR HE 0437-5439, THE HYPERVELOCITY STAR NEAR THE LARGE MAGELLANIC CLOUD

    SciTech Connect

    Brown, Warren R.; Geller, Margaret J.; Kenyon, Scott J.; Anderson, Jay; Bond, Howard E.; Livio, Mario; Gnedin, Oleg Y. E-mail: mgeller@cfa.harvard.ed E-mail: jayander@stsci.ed E-mail: mlivio@stsci.ed

    2010-08-10

    We use Hubble Space Telescope imaging to measure the absolute proper motion of the hypervelocity star (HVS) HE 0437-5439, a short-lived B star located in the direction of the Large Magellanic Cloud (LMC). We observe ({mu}{sub {alpha}} {mu}{sub {delta}}) = (+0.53 {+-} 0.25(stat) {+-} 0.33(sys), + 0.09 {+-} 0.21(stat) {+-} 0.48(sys)) mas yr{sup -1}. The velocity vector points directly away from the center of the Milky Way; an origin from the center of the LMC is ruled out at the 3{sigma} level. The flight time of the HVS from the Milky Way exceeds its main-sequence lifetime, thus its stellar nature requires it to be a blue straggler. The large space velocity rules out a Galactic-disk ejection. Combining the HVS's observed trajectory, stellar nature, and required initial velocity, we conclude that HE 0437-5439 was most likely a compact binary ejected by the Milky Way's central black hole.

  10. Breathing motion compensated reconstruction for C-arm cone beam CT imaging: initial experience based on animal data

    NASA Astrophysics Data System (ADS)

    Schäfer, D.; Lin, M.; Rao, P. P.; Loffroy, R.; Liapi, E.; Noordhoek, N.; Eshuis, P.; Radaelli, A.; Grass, M.; Geschwind, J.-F. H.

    2012-03-01

    C-arm based tomographic 3D imaging is applied in an increasing number of minimal invasive procedures. Due to the limited acquisition speed for a complete projection data set required for tomographic reconstruction, breathing motion is a potential source of artifacts. This is the case for patients who cannot comply breathing commands (e.g. due to anesthesia). Intra-scan motion estimation and compensation is required. Here, a scheme for projection based local breathing motion estimation is combined with an anatomy adapted interpolation strategy and subsequent motion compensated filtered back projection. The breathing motion vector is measured as a displacement vector on the projections of a tomographic short scan acquisition using the diaphragm as a landmark. Scaling of the displacement to the acquisition iso-center and anatomy adapted volumetric motion vector field interpolation delivers a 3D motion vector per voxel. Motion compensated filtered back projection incorporates this motion vector field in the image reconstruction process. This approach is applied in animal experiments on a flat panel C-arm system delivering improved image quality (lower artifact levels, improved tumor delineation) in 3D liver tumor imaging.

  11. Marine cloud brightening

    PubMed Central

    Latham, John; Bower, Keith; Choularton, Tom; Coe, Hugh; Connolly, Paul; Cooper, Gary; Craft, Tim; Foster, Jack; Gadian, Alan; Galbraith, Lee; Iacovides, Hector; Johnston, David; Launder, Brian; Leslie, Brian; Meyer, John; Neukermans, Armand; Ormond, Bob; Parkes, Ben; Rasch, Phillip; Rush, John; Salter, Stephen; Stevenson, Tom; Wang, Hailong; Wang, Qin; Wood, Rob

    2012-01-01

    The idea behind the marine cloud-brightening (MCB) geoengineering technique is that seeding marine stratocumulus clouds with copious quantities of roughly monodisperse sub-micrometre sea water particles might significantly enhance the cloud droplet number concentration, and thereby the cloud albedo and possibly longevity. This would produce a cooling, which general circulation model (GCM) computations suggest could—subject to satisfactory resolution of technical and scientific problems identified herein—have the capacity to balance global warming up to the carbon dioxide-doubling point. We describe herein an account of our recent research on a number of critical issues associated with MCB. This involves (i) GCM studies, which are our primary tools for evaluating globally the effectiveness of MCB, and assessing its climate impacts on rainfall amounts and distribution, and also polar sea-ice cover and thickness; (ii) high-resolution modelling of the effects of seeding on marine stratocumulus, which are required to understand the complex array of interacting processes involved in cloud brightening; (iii) microphysical modelling sensitivity studies, examining the influence of seeding amount, seed-particle salt-mass, air-mass characteristics, updraught speed and other parameters on cloud–albedo change; (iv) sea water spray-production techniques; (v) computational fluid dynamics studies of possible large-scale periodicities in Flettner rotors; and (vi) the planning of a three-stage limited-area field research experiment, with the primary objectives of technology testing and determining to what extent, if any, cloud albedo might be enhanced by seeding marine stratocumulus clouds on a spatial scale of around 100×100 km. We stress that there would be no justification for deployment of MCB unless it was clearly established that no significant adverse consequences would result. There would also need to be an international agreement firmly in favour of such action

  12. Stratocumulus cloud evolution

    SciTech Connect

    Yang, X.; Rogers, D.P.; Norris, P.M.; Johnson, D.W.; Martin, G.M.

    1994-12-31

    The structure and evolution of the extra-tropical marine atmospheric boundary layer (MABL) depends largely on the variability of stratus and stratocumulus clouds. The typical boundary-layer is capped by a temperature inversion that limits exchange with the free atmosphere. Cloud-top is usually coincident with the base of the inversion. Stratus clouds are generally associated with a well-mixed MABL, whereas daytime observations of stratocumulus-topped boundary-layers indicate that the cloud and subcloud layers are often decoupled due to shortwave radiative heating of the cloud layer. In this case the surface-based mixed layer is separated from the base of the stratocumulus (Sc) by a layer that is stable to dry turbulent mixing. This is sometimes referred to as the transition layer. Often cumulus clouds (Cu) develop in the transition layer. The cumulus tops may remain below the Sc base or they may penetrate into the Sc layer and occasionally through the capping temperature inversion. While this cloud structure is characteristic of the daytime MABL, it may persist at night also. The Cu play an important role in connecting the mixed layer to the Sc layer. If the Cu are active they transport water vapor from the sea surface that maintains the Sc against the dissipating effects of shortwave heating. The Cu, however, are very sensitive to small changes in the heat and moisture in the boundary-layer and are transient features. Here the authors discuss the effect of these small Cu on the turbulent structure of the MABL.

  13. Collisional excitation of molecules in dense interstellar clouds

    NASA Technical Reports Server (NTRS)

    Green, S.

    1985-01-01

    State transitions which permit the identification of the molecular species in dense interstellar clouds are reviewed, along with the techniques used to calculate the transition energies, the database on known molecular transitions and the accuracy of the values. The transition energies cannot be measured directly and therefore must be modeled analytically. Scattering theory is used to determine the intermolecular forces on the basis of quantum mechanics. The nuclear motions can also be modeled with classical mechanics. Sample rate constants are provided for molecular systems known to inhabit dense interstellar clouds. The values serve as a database for interpreting microwave and RF astrophysical data on the transitions undergone by interstellar molecules.

  14. Images from Galileo of the Venus cloud deck

    NASA Technical Reports Server (NTRS)

    Belton, Michael J. S.; Gierasch, Peter J.; Smith, Michael D.; Helfenstein, Paul; Schinder, Paul J.; Pollack, James B.; Rages, Kathy A.; Morrison, David; Klaasen, Kenneth P.; Pilcher, Carl B.

    1991-01-01

    Images of Venus taken at 418 and 986 nm show that the morphology and motions of large-scale features change with depth in the cloud deck. Poleward meridional velocities, seen in both spectral regions, are much reduced in the NIR. In the south polar region the markings in the two wavelength bands are strongly anticorrelated. The images follow the changing state of the upper cloud layer downwind of the subsolar point, and the zonal flowfield shows a longitudinal periodicity that may be coupled to the formation of large-scale planetary waves. No optical lightning was detected.

  15. Images from Galileo of the Venus cloud deck

    USGS Publications Warehouse

    Belton, M.J.S.; Gierasch, P.J.; Smith, M.D.; Helfenstein, P.; Schinder, P.J.; Pollack, James B.; Rages, K.A.; Ingersoll, A.P.; Klaasen, K.P.; Veverka, J.; Anger, C.D.; Carr, M.H.; Chapman, C.R.; Davies, M.E.; Fanale, F.P.; Greeley, R.; Greenberg, R.; Head, J. W., III; Morrison, D.; Neukum, G.; Pilcher, C.B.

    1991-01-01

    Images of Venus taken at 418 (violet) and 986 [near-infrared (NIR)] nanometers show that the morphology and motions of large-scale features change with depth in the cloud deck. Poleward meridional velocities, seen in both spectral regions, are much reduced in the NIR. In the south polar region the markings in the two wavelength bands are strongly anticorrelated. The images follow the changing state of the upper cloud layer downwind of the subsolar point, and the zonal flow field shows a longitudinal periodicity that may be coupled to the formation of large-scale planetary waves. No optical lightning was detected.

  16. Ulysses observations of electron and proton components in a magnetic cloud and related wave activity

    NASA Technical Reports Server (NTRS)

    Osherovich, V. A.; Fainberg, J.; Stone, R. G.; MacDowall, R. J.; Phillips, J. L.; Balogh, A.

    1995-01-01

    In addition to a smooth rotation of the magnetic field vector, magnetic clouds have a low proton temperature T(sub p). Their expansion in the solar wind leads to depletion and therefore the ion component cools down. It has been shown recently that the electron component in magnetic clouds behaves differently: when the cloud expands, electron temperature Te anti correlates with density and therefore Te increases in the cloud, creating favorable conditions for the rise of ion-acoustic waves. For the magnetic cloud observed by Ulysses on June 10 - 12, 1993 at 4.64 AU at S 32.5 deg, we present observations for both electron and proton components and related plasma wave activity. Our results confirm the anti correlation between T(sub e) and electron density and also exhibit a high ratio of T(sub e)/T(sub P) in the cloud. Since Landau damping is not effective for T(sub e)/T(sub p) much greater than 1, Doppler shifted ion acoustic waves are expected in the cloud. Calculation of ion acoustic wave frequencies in the cloud and comparison with observed wave activity confirm this expectation. As in our previous work, we show that the electron component in the cloud obeys a polytropic law with gamma is less than 1 (gamma approximately equals 0.3-0.4). The dynamics of the magnetic cloud are determined to a large degree by the dominating electron pressure.

  17. Numerical Modeling of Cloud Convection in Jupiter's Atmosphere: robustness and a mechanism of the intermittent emergence of vigorous cumulonimbus clouds

    NASA Astrophysics Data System (ADS)

    Sugiyama, K.; Nakajima, K.; Odaka, M.; Ishiwatari, M.; Kuramoto, K.; Nishizawa, S.; Takahashi, Y. O.; Hayashi, Y.

    2012-12-01

    The mean structure of cloud layer of Jupiter's atmosphere is thought to be maintained by the statistical contribution of a large number of clouds driven by internal and radiative heating/cooling over multiple cloud life cycles. The mean structure and its relationship to cloud convection remain unclear, because it is difficult to observe the structure under the extensive surface cloud layer by remote sensing. Sugiyama et al. (2009) develop a two-dimensional numerical fluid model that incorporates condensation of H2O and NH3 and production reaction of NH4SH, and Sugiyama et al. (2011) investigate a possible cloud layer structure with thermal forcing whose intensity is of the order of that expected in the real Jupiter's atmosphere. The purpose of this study is to confirm robustness of the characteristics of the structure demonstrated by Sugiyama et al. (2011) and to discuss a mechanism that causes their most remarkable characteristic, intermittent emergence of vigorous cumulonimbus clouds. Many long-term numerical calculations are performed in order to examine the dependency of the structure of cloud layer on both key parameter of cloud microphysics and abundance of condensible gases in the sub-cloud layer. In the parameter study about the time scale of conversion from cloud to rain, the intermittent cloud activity exists. In the parameter study about the abundance of the condensible gases in sub-cloud layer, the intermittent cloud activity exists except for the case in which the abundance of condensible gases is extremely small. The period of the intermittency is roughly proportional to the abundance of H2O gas in the sub-cloud layer. As the abundance of condensible gases increases, the condensation levels and the formation level become stronger barrier for the vertical convective motion. Our results do not reproduce the Galileo probe observation that all of the condensible gases are significantly depleted below the H2O condensation level. The trigger that starts

  18. Exploiting motion-based redundancy to enhance microgrid polarimeter imagery

    NASA Astrophysics Data System (ADS)

    Ratliff, Bradley M.; Tyo, J. Scott; Black, Wiley T.; LaCasse, Charles F.

    2009-08-01

    Microgrid polarimeters are a type of division of focal plane (DoFP) imaging polarimeter that contains a mosaic of pixel-wise micropolarizing elements superimposed upon an FPA sensor. Such a device measures a slightly different polarized state at each pixel. These measurements are combined to estimate the Stokes vector at each pixel in the image. DoFP devices have the advantage that they can obtain Stokes vector image estimates for an entire scene from a single frame capture. However, they suffer from the disadvantage that the neighboring measurements that are used to estimate the Stokes vector images are acquired at differing instantaneous fields of view (IFOV). This IFOV issue leads to false polarization signatures that significantly degrade the Stokes vector images. Interpolation and other image processing strategies can be employed to reduce IFOV artifacts; however these techniques have a limit to the amount of enhancement they can provide on a single microgrid image. Here we investigate algorithms that use multiple microgrid images that contain frame-to-frame global motion to further enhance the Stokes vector image estimates. Motion-based imagery provides additional redundancy that can be exploited to recover information that is "missing" from a single microgrid frame capture. We have found that IFOV and aliasing artifacts can be defeated entirely when these types of algorithms are applied to the data prior to Stokes vector estimation. We demonstrate results on real LWIR microgrid data using a particular resolution enhancement technique from the literature.

  19. Long-term Behaviour Of Venus Winds At Cloud Level From Virtis/vex Observations

    NASA Astrophysics Data System (ADS)

    Hueso, Ricardo; Peralta, J.; Sánchez-Lavega, A.; Pérez-Hoyos, S.; Piccioni, G.; Drossart, P.

    2009-09-01

    The Venus Express (VEX) mission has been in orbit to Venus for more than three years now. The VIRTIS instrument onboard VEX observes Venus in two channels (visible and infrared) obtaining spectra and multi-wavelength images of the planet. Images in the ultraviolet range are used to study the upper cloud at 66 km while images in the infrared (1.74 μm) map the opacity of the lower cloud deck at 48 km. Here we present an analysis of the overall dynamics of Venus’ atmosphere at both levels using observations that cover a large fraction of the VIRTIS dataset. We will present our latest results concerning the zonal winds, the overall stability in the lower cloud deck motions and the variability in the upper cloud. Meridional winds are also observed in the upper and lower cloud in the UV and IR images obtained with VIRTIS. While the upper clouds present a net meridional motion consistent with the upper branch of a Hadley cell the lower cloud present more irregular, variable and less intense motions in the meridional direction. Acknowledgements This work has been funded by Spanish MEC AYA2006-07735 with FEDER support and Grupos Gobierno Vasco IT-464-07. RH acknowledges a "Ramón y Cajal” contract from MEC.

  20. Vector representation of tourmaline compositions

    NASA Technical Reports Server (NTRS)

    Burt, Donald M.

    1989-01-01

    The vector method for representing mineral compositions of amphibole and mica groups is applied to the tourmaline group. Consideration is given to the methods for drawing the relevant vector diagrams, relating the exchange vectors to one another, and contouring the diagrams for constant values of Na, Ca, Li, Fe, Mg, Al, Si, and OH. The method is used to depict a wide range of possible tourmaline end-member compositions and solid solutions, starting from a single point. In addition to vector depictions of multicomponent natural tourmalines, vectors are presented for simpler systems such as (Na,Al)-tourmalines, alkali-free tourmalines, and elbaites.