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1

Cloud Base Height and Effective Cloud Emissivity Retrieval with Ground-Based Infrared Interferometer  

NASA Astrophysics Data System (ADS)

Based on ground-based Atmospheric Emitted Radiance Interferometer (AERI) observations in Shouxian, Anhui province, China, the cloud base height (CBH) and effective cloud emissivity are retrieved by using the minimum root-mean-square difference method. This method was originally developed for satellite remote sensing. The high-temporal-resolution retrieval results can depict the trivial variations of the zenith clouds continuously. The retrieval results are evaluated by comparing them with observations by the cloud radar. The comparison shows that the retrieval bias is smaller for the middle and low clouds, especially for opaque clouds. When two layers of clouds exist, the retrieval results reflect the weighting radiative contribution of the multi-layer cloud. The retrieval accuracy is affected by uncertainties of the AERI radiances and sounding profiles, in which the role of uncertainty in the temperature profile is dominant.

Pan, L.; Lu, D.

2012-12-01

2

Cumulus cloud base height estimation from high spatial resolution Landsat data - A Hough transform approach  

NASA Technical Reports Server (NTRS)

A semiautomated methodology is developed for estimating cumulus cloud base heights on the basis of high spatial resolution Landsat MSS data, using various image-processing techniques to match cloud edges with their corresponding shadow edges. The cloud base height is then estimated by computing the separation distance between the corresponding generalized Hough transform reference points. The differences between the cloud base heights computed by these means and a manual verification technique are of the order of 100 m or less; accuracies of 50-70 m may soon be possible via EOS instruments.

Berendes, Todd; Sengupta, Sailes K.; Welch, Ron M.; Wielicki, Bruce A.; Navar, Murgesh

1992-01-01

3

Latitudinal variations of cloud base height and lightning parameters in the tropics  

NASA Technical Reports Server (NTRS)

The observed reduction in cloud-to-ground lightning in the new-equational zone is examined from the perspective of the width of the main negative charge region. Thermodynamic observations of cloud base height also show a climatological minimum value in the near-equatorial region. The association of low cloud base with both narrow updrafts and narrow changing zones may impede the bridging of the large air gap to ground, and thereby suppress cloud-to-ground lightning activity. This width dependence may be more important than the approx. 10% variation in height of the freezing level in the encouraging flashes to ground.

Mushtak, V. C.; Williams, E. R.; Boccippio, D. J.

2006-01-01

4

The computation of cloud base height from paired whole-sky imaging cameras  

SciTech Connect

A major goal for global change studies is to improve the accuracy of general circulation models (GCMs) capable of predicting the timing and magnitude of greenhouse gas-induced global warming. Research has shown that cloud radiative feedback is the single most important effect determining the magnitude of possible climate responses to human activity. Of particular value to reducing the uncertainties associated with cloud-radiation interactions is the measurement of cloud base height (CBH), both because it is a dominant factor in determining the infrared radiative properties of clouds with respect to the earth`s surface and lower atmosphere and because CBHs are essential to measuring cloud cover fraction. We have developed a novel approach to the extraction of cloud base height from pairs of whole sky imaging (WSI) cameras. The core problem is to spatially register cloud fields from widely separated WSI cameras; this complete, triangulation provides the CBH measurements. The wide camera separation (necessary to cover the desired observation area) and the self-similarity of clouds defeats all standard matching algorithms when applied to static views of the sky. To address this, our approach is based on optical flow methods that exploit the fact that modern WSIs provide sequences of images. We will describe the algorithm and present its performance as evaluated both on real data validated by ceilometer measurements and on a variety of simulated cases.

Allmen, M.C.; Kegelmeyer, W.P. Jr.

1994-03-01

5

New Stereo Vision Digital Camera System for Simultaneous Measurement of Cloud Base Height and Atmospheric Visibility  

NASA Astrophysics Data System (ADS)

Clouds play an important role in many aspects of everyday life. They affect both the local weather as well as the global climate and are an important parameter on climate change studies. Cloud parameters are also important for weather prediction models which make use of actual measurements. It is thus important to have low-cost instrumentation that can be deployed in the field to measure those parameters. This kind of instruments should also be automated and robust since they may be deployed in remote places and be subject to adverse weather conditions. Although clouds are very important in environmental systems, they are also an essential component of airplane safety when visual flight rules (VFR) are enforced, such as in most small aerodromes where it is not economically viable to install instruments for assisted flying. Under VFR there are strict limits on the height of the cloud base, cloud cover and atmospheric visibility that ensure the safety of the pilots and planes. Although there are instruments, available in the market, to measure those parameters, their relatively high cost makes them unavailable in many local aerodromes. In this work we present a new prototype which has been recently developed and deployed in a local aerodrome as proof of concept. It is composed by two digital cameras that capture photographs of the sky and allow the measurement of the cloud height from the parallax effect. The new developments consist on having a new geometry which allows the simultaneous measurement of cloud base height, wind speed at cloud base height and atmospheric visibility, which was not previously possible with only two cameras. The new orientation of the cameras comes at the cost of a more complex geometry to measure the cloud base height. The atmospheric visibility is calculated from the Lambert-Beer law after the measurement of the contrast between a set of dark objects and the background sky. The prototype includes the latest hardware developments that allow its cost to remain low even with its increased functionality. Also, a new control software was also developed to ensure that the two cameras are triggered simultaneously. This is a major requirement that affects the final uncertainty of the measurements due to the constant movement of the clouds in the sky. Since accurate orientation of the cameras can be a very demanding task in field deployments, an automated calibration procedure has been developed, that removes the need for an accurate alignment. It consists on photographing the stars, which do not exhibit parallax due to the long distances involved, and deducing the inherent misalignments of the two cameras. The known misalignments are then used to correct the cloud photos. These developments will be described in the detail, along with an uncertainty analysis of the measurement setup. Measurements of cloud base height and atmospheric visibility will be presented and compared with measurements from other in-situ instruments. This work was supported by FCT project PTDC/CTE-ATM/115833/2009 and Program COMPETE FCOMP-01-0124-FEDER-014508

Janeiro, F. M.; Carretas, F.; Palma, N.; Ramos, P. M.; Wagner, F.

2013-12-01

6

Evaluation of Satellite-Based Upper Troposphere Cloud Top Height Retrievals in Multilayer Cloud Conditions During TC4  

NASA Technical Reports Server (NTRS)

Upper troposphere cloud top heights (CTHs), restricted to cloud top pressures (CTPs) less than 500 hPa, inferred using four satellite retrieval methods applied to Twelfth Geostationary Operational Environmental Satellite (GOES-12) data are evaluated using measurements during the July August 2007 Tropical Composition, Cloud and Climate Coupling Experiment (TC4). The four methods are the single-layer CO2-absorption technique (SCO2AT), a modified CO2-absorption technique (MCO2AT) developed for improving both single-layered and multilayered cloud retrievals, a standard version of the Visible Infrared Solar-infrared Split-window Technique (old VISST), and a new version of VISST (new VISST) recently developed to improve cloud property retrievals. They are evaluated by comparing with ER-2 aircraft-based Cloud Physics Lidar (CPL) data taken during 9 days having extensive upper troposphere cirrus, anvil, and convective clouds. Compared to the 89% coverage by upper tropospheric clouds detected by the CPL, the SCO2AT, MCO2AT, old VISST, and new VISST retrieved CTPs less than 500 hPa in 76, 76, 69, and 74% of the matched pixels, respectively. Most of the differences are due to subvisible and optically thin cirrus clouds occurring near the tropopause that were detected only by the CPL. The mean upper tropospheric CTHs for the 9 days are 14.2 (+/- 2.1) km from the CPL and 10.7 (+/- 2.1), 12.1 (+/- 1.6), 9.7 (+/- 2.9), and 11.4 (+/- 2.8) km from the SCO2AT, MCO2AT, old VISST, and new VISST, respectively. Compared to the CPL, the MCO2AT CTHs had the smallest mean biases for semitransparent high clouds in both single-layered and multilayered situations whereas the new VISST CTHs had the smallest mean biases when upper clouds were opaque and optically thick. The biases for all techniques increased with increasing numbers of cloud layers. The transparency of the upper layer clouds tends to increase with the numbers of cloud layers.

Chang, Fu-Lung; Minnis, Patrick; Ayers, J. Kirk; McGill, Matthew J.; Palikonda, Rabindra; Spangenberg, Douglas A.; Smith, William L., Jr.; Yost, Christopher R.

2010-01-01

7

Evaluating a lightning parameterization based on cloud-top height for mesoscale numerical model simulations  

NASA Astrophysics Data System (ADS)

The Price and Rind lightning parameterization based on cloud-top height is a commonly used method for predicting flash rate in global chemistry models. As mesoscale simulations begin to implement flash rate predictions at resolutions that partially resolve convection, it is necessary to validate and understand the behavior of this method within such a regime. In this study, we tested the flash rate parameterization, intra-cloud/cloud-to-ground (IC:CG) partitioning parameterization, and the associated resolution dependency "calibration factor" by Price and Rind using the Weather Research and Forecasting (WRF) model running at 36 km, 12 km, and 4 km grid spacings within the continental United States. Our results show that while the integrated flash count is consistent with observations when model biases in convection are taken into account, an erroneous frequency distribution is simulated. When the spectral characteristics of lightning flash rate are a concern, we recommend the use of prescribed IC:CG values. In addition, using cloud-top from convective parameterization, the "calibration factor" is also shown to be insufficient in reconciling the resolution dependency at the tested grid spacing used in this study. We recommend scaling by areal ratio relative to a base-case grid spacing determined by convective core density.

Wong, J.; Barth, M. C.; Noone, D.

2013-04-01

8

Impact of Arctic sea-ice retreat on the recent change in cloud-base height during autumn  

NASA Astrophysics Data System (ADS)

Cloud-base observations over the ice-free Chukchi and Beaufort Seas in autumn were conducted using a shipboard ceilometer and radiosondes during the 1999-2010 cruises of the Japanese R/V Mirai. To understand the recent change in cloud base height over the Arctic Ocean, these cloud-base height data were compared with the observation data under ice-covered situation during SHEBA (the Surface Heat Budget of the Arctic Ocean project in 1998). Our ice-free results showed a 30 % decrease (increase) in the frequency of low clouds with a ceiling below (above) 500 m. Temperature profiles revealed that the boundary layer was well developed over the ice-free ocean in the 2000s, whereas a stable layer dominated during the ice-covered period in 1998. The change in surface boundary conditions likely resulted in the difference in cloud-base height, although it had little impact on air temperatures in the mid- and upper troposphere. Data from the 2010 R/V Mirai cruise were investigated in detail in terms of air-sea temperature difference. This suggests that stratus cloud over the sea ice has been replaced as stratocumulus clouds with low cloud fraction due to the decrease in static stability induced by the sea-ice retreat. The relationship between cloud-base height and air-sea temperature difference (SST-Ts) was analyzed in detail using special section data during 2010 cruise data. Stratus clouds near the sea surface were predominant under a warm advection situation, whereas stratocumulus clouds with a cloud-free layer were significant under a cold advection situation. The threshold temperature difference between sea surface and air temperatures for distinguishing the dominant cloud types was 3 K. Anomalous upward turbulent heat fluxes associated with the sea-ice retreat have likely contributed to warming of the lower troposphere. Frequency distribution of the cloud-base height (km) detected by a ceilometer/lidar (black bars) and radiosondes (gray bars), and profiles of potential temperature (K) for (a) ice-free cases (R/V Mirai during September) and (b) ice-covered case (SHEBA during September 1998). (c) Vertical profiles of air temperature from 1000 hPa to 150 hPa (solid lines: observations north of 75°N, and dashed lines: the ERA-Interim reanalysis over 75-82.5°N, 150-170°W). Green, blue, and red lines denote profiles derived from observations by NP stations (the 1980s), SHEBA (1998), and the R/V Mirai (the 2000s), respectively. (d) Temperature trend calculated by the ERA-Interim reanalysis over the area.

Sato, K.; Inoue, J.; Kodama, Y.; Overland, J. E.

2012-12-01

9

Development of an analysis tool for cloud base height and visibility  

NASA Astrophysics Data System (ADS)

The meteorological variables cloud base height (CBH) and horizontal atmospheric visibility (VIS) at surface level are of vital importance for safety and effectiveness in aviation. Around 20% of all civil aviation accidents in the USA from 2003 to 2007 were due to weather related causes, around 18% of which were owing to decreased visibility or ceiling (main CBH). The aim of this study is to develop a system generating quality-controlled gridded analyses of the two parameters based on the integration of various kinds of observational data. Upon completion, the tool is planned to provide guidance for nowcasting during take-off and landing as well as for flights operated under visual flight rules. Primary input data consists of manual as well as instrumental observation of CBH and VIS. In Austria, restructuring of part of the standard meteorological stations from human observation to automatic measurement of VIS and CBH is currently in progress. As ancillary data, satellite derived products can add 2-dimensional information, e.g. Cloud Type by NWC SAF (Nowcasting Satellite Application Facilities) MSG (Meteosat Second Generation). Other useful available data are meteorological surface measurements (in particular of temperature, humidity, wind and precipitation), radiosonde, radar and high resolution topography data. A one-year data set is used to study the spatial and weather-dependent representativeness of the CBH and VIS measurements. The VERA (Vienna Enhanced Resolution Analysis) system of the Institute of Meteorology and Geophysics of the University of Vienna provides the framework for the analysis development. Its integrated "Fingerprint" technique allows the insertion of empirical prior knowledge and ancillary information in the form of spatial patterns. Prior to the analysis, a quality control of input data is performed. For CBH and VIS, quality control can consist of internal consistency checks between different data sources. The possibility of two-dimensional consistency checks has to be explored. First results in the development of quality control features and fingerprints will be shown.

Umdasch, Sarah; Reinhold, Steinacker; Manfred, Dorninger; Markus, Kerschbaum; Wolfgang, Pöttschacher

2014-05-01

10

Estimation of cirrus and stratus cloud heights using landsat imagery  

SciTech Connect

A new method based upon high-spatial-resolution imagery is presented that matches cloud and shadow regions to estimate cirrus and stratus cloud heights. The distance between the cloud and the matching shadow pattern is accomplished using the 2D cross-correlation function from which the cloud height is derived. The distance between the matching cloud-shadow patterns is verified manually. The derived heights also are validated through comparison with a temperature-based retrieval of cloud height. It is also demonstrated that an estimate of cloud thickness can be retrieved if both the sunside and antisunside of the cloud-shadow pair are apparent. The technique requires some interpretation to determine the cloud height level retrieved (i.e., the top, base, or mid-level). It is concluded that the method is accurate to within several pixels, equivalent to cloud height variations of about {plus_minus}250 m. The results show that precise placement of the templates is unnecessary, so that the development of a semiautomated procedure is possible. Cloud templates of about 64 pixels on a side or larger produce consistent results. The procedure was repeated for imagery degraded to simulate lower spatial resolutions. The results suggest that spatial resolution of 150-200 m or better is necessary in order to obtain stable cloud height retrievals. 22 refs., 13 figs., 4 tabs.

Inomata, Yasushi; Feind, R.E.; Welch, R.M. [South Dakota School of Mines and Technology, Rapid City, SD (United States)] [South Dakota School of Mines and Technology, Rapid City, SD (United States)

1996-03-01

11

Estimation of Cirrus and Stratus Cloud Heights Using Landsat Imagery  

NASA Technical Reports Server (NTRS)

A new method based upon high-spatial-resolution imagery is presented that matches cloud and shadow regions to estimate cirrus and stratus cloud heights. The distance between the cloud and the matching shadow pattern is accomplished using the 2D cross-correlation function from which the cloud height is derived. The distance between the matching cloud-shadow patterns is verified manually. The derived heights also are validated through comparison with a temperature-based retrieval of cloud height. It is also demonstrated that an estimate of cloud thickness can be retrieved if both the sunside and anti-sunside of the cloud-shadow pair are apparent. The technique requires some intepretation to determine the cloud height level retrieved (i.e., the top, base, or mid-level). It is concluded that the method is accurate to within several pixels, equivalent to cloud height variations of about +/- 250 m. The results show that precise placement of the templates is unnecessary, so that the development of a semi-automated procedure is possible. Cloud templates of about 64 pixels on a side or larger produce consistent results. The procedure was repeated for imagery degraded to simulate lower spatial resolutions. The results suggest that spatial resolution of 150-200 m or better is necessary in order to obtain stable cloud height retrievals.

Inomata, Yasushi; Feind, R. E.; Welch, R. M.

1996-01-01

12

Trends in Low and High Cloud Boundaries and Errors in Height Determination of Cloud Boundaries.  

NASA Astrophysics Data System (ADS)

Clouds are important to climate and climate trends. To determine trends in cloud-base heights and cloud-top heights, the Comprehensive Aerological Reference Data Set (CARDS) and the method of Chernykh and Eskridge are used to diagnose cloud base, top, and amount. Trends in time series of cloud bases and tops at 795 radiosonde stations from 1964 to 1998 are presented. It was found that trends in cloud-base height and cloud-top height are seasonally dependent and a function of cloud cover amount. There was a small increase in multilayer cloudiness in all seasons. Geographical distributions of decadal changes of cloud bases and tops were spatially nonuniform and depended upon the season. To estimate the errors made in calculating the heights of cloud boundaries, an analysis was made of the response of the thermistors and hygristors. Thermistors and hygristors are linear sensors of the first order. From this it is shown that the distance between calculated inflection points (cloud boundaries) of observed and true values is exactly equal to the time constant of the sensor times the balloon speed. More accurate cloud boundaries can be determined using this finding.

Chernykh, Irina V.; Alduchov, Oleg A.; Eskridge, Robert E.

2001-09-01

13

Predicting Daily Insolation with Hourly Cloud Height and Coverage.  

NASA Astrophysics Data System (ADS)

Solar radiation information is used in crop growth, boundary layer, entomological and plant pathological models, and in determining the potential use of active and passive solar energy systems. Yet solar radiation is among the least measured meteorological variables.A semi-physical model based on standard meteorological data was developed to estimate solar radiation received at the earth's surface. The radiation model includes the effects of Rayleigh scattering, absorption by water vapor and permanent gases, and absorption and scattering by aerosols and clouds. Cloud attenuation is accounted for by assigning transmission coefficients based on cloud height and amount. The cloud transmission coefficients for various heights and coverages were derived empirically from hourly observations of solar radiation in conjunction with corresponding cloud observations at West Lafayette, Indiana. The model was tested with independent data from West Lafayette and Indianapolis, Madison, WI, Omaha, NE, Columbia, MO, Nashville, TN, Seattle, WA, Los Angeles, CA, Phoenix, AZ, Lake Charles, LA, Miami, FL, and Sterling, VA. For each of these locations a 16% random sample of days was drawn within each of the 12 months in a year for testing the model. Excellent agreement between predicted and observed radiation values was obtained for all stations tested. Mean absolute errors ranged from 1.05 to 1.80 MJ m2 day1 and root-mean-square errors ranged from 1.31 to 2.32 MJ m2 day1. The model's performance judged by relative error was found to be independent of season and cloud amount for all locations tested.

Meyers, T. P.; Dale, R. F.

1983-04-01

14

Stereographic cloud heights from SMS/goes imagery  

NASA Technical Reports Server (NTRS)

Stereographic pairs of SMS/GOES images, generated simultaneously by the spin-scan cameras of each of two geostationary satellites (SMS 1 and SMS2), separated by 32 degrees of longitude on February 1, 1975, were analyzed photogrametrically to yield cloud heights with a two-sigma uncertainty of 500 meters. These cloud heights compare favorably with heights of the same clouds measured by radar and IR methods. The same SMS image pairs were used to measure mountaintop heights with a mean deviation of 0.24 km from cartographic values.

Minzner, R. A.; Shenk, W. E.; Teagle, R. D.; Steranka, J.

1977-01-01

15

Stratocumulus Cloud-Top Height Estimates and Their Climatic Implications PAQUITA ZUIDEMA AND DAVID PAINEMAL  

E-print Network

Stratocumulus Cloud-Top Height Estimates and Their Climatic Implications PAQUITA ZUIDEMA AND DAVID-rate dependence on boundary layer height is weak, decreasing from a best fit of 7.6 to 7.2 K km21 as the boundary layer deepens from 800 m to 2 km. Ship-based cloud-base heights up to 800 m correspond well to lifting

Zuidema, Paquita

16

Insights into Cloud-Top Height and Dynamics from the Seasonal Cycle of Cloud-Top Heights Observed by MISR in the West Pacific Region  

E-print Network

Insights into Cloud-Top Height and Dynamics from the Seasonal Cycle of Cloud-Top Heights Observed July 2009) ABSTRACT The connection between environmental stability and the height of tropical deep convective clouds is an- alyzed using stereo cloud height data from the Multiangle Imaging Spectroradiometer

Sherwood, Steven

17

Enhanced IR imagery of cloud top temperatures, heights, cloud types and organizational patterns  

NSDL National Science Digital Library

Dorothea Ivanova, Embry-Riddle Aeronautical University Summary The object of this activity is to find enhanced IR imagery, to interpret cloud top temperatures and heights and to identify cloud types and ...

Dorothea Ivanova

18

Stratocumulus cloud height variations determined from surface and satellite observations  

NASA Technical Reports Server (NTRS)

Determination of cloud-top heights from satellite-inferred cloud-top temperatures is a relatively straightforward procedure for a well-behaved troposphere. The assumption of a monotonically decreasing temperature with increasing altitude is commonly used to assign a height to a given cloud-top temperature. In the hybrid bispectral threshold method, or HBTM, Minnis et al. (1987) assume that the lapse rate for the troposphere is -6.5/Kkm and that the surface temperature which calibrated this lapse rate is the 24 hour mean of the observed or modeled clear-sky, equivalent blackbody temperature. The International Satellite Cloud Climatology Project (ISCCP) algorithm (Rossow et al., 1988) attempts a more realistic assignment of height by utilizing interpolations of analyzed temperature fields from the National Meteorological Center (NMC) to determine the temperature at a given level over the region of interest. Neither these nor other techniques have been tested to any useful extent. The First ISCCP Regional Experiment (FIRE) Intensive Field Observations (IFO) provide an excellent opportunity to assess satellite-derived cloud height results because of the availability of both direct and indirect cloud-top altitude data of known accuracy. The variations of cloud-top altitude during the Marine Stratocumulus IFO (MSIFO, June 29 to July 19, 1987) derived from surface, aircraft, and satellite data are examined.

Minnis, Patrick; Young, David F.; Davies, R.; Blaskovic, M.; Albrecht, Bruce A.

1990-01-01

19

Stereographic cloud heights from imagery of SMS/GOES satellites  

NASA Technical Reports Server (NTRS)

Stereographic pairs of SMS/GOES images, generated simultaneously by the spin-scan cameras of each of two geostationary satellites (SMS 1 and SMS 2, separated by 32 degrees of longitude on February 17, 1975), have been analyzed photogrammetrically to yield cloud heights with a two-sigma uncertainty of 500 meters. The 32-degree angle between the image plane of the two satellites, plus the distortions involved in transferring the image of a nearly full hemisphere of the earth onto a plane, required the development of a special instrument to permit stereographic compilation. Cloud heights measured stereographically compared favorably with heights of the same clouds measured by radar and IR methods. The same SMS image pairs were used to measure mountain-top heights with a mean deviation of 0.24 km from cartographic values.

Minzner, R. A.; Shenk, W. E.; Teagle, R. D.; Steranka, J.

1978-01-01

20

A Polar Specific 20-year Data Set of Cloud Fraction and Height Derived from Satellite Radiances  

NASA Technical Reports Server (NTRS)

This is a final report to fulfill reporting requirements on NASA grant NASA NAG5-11800. Jennifer Francis, PI at Rutgers University is currently continuing work on this project under a no-cost extension. Work at the University of Washington portion of the project is completed and reported here. Major accomplishments and results from this portion of the project include: 1) Extension and reprocessing of TOVS Polar Pathfinder (Path-P) data set; 2) Analysis of Arctic cloud variability; 3) Validation of Southern Hemisphere ocean cloud retrievals; 4) Intercompared cloud height information from AVHRR retrievals and surface-based cloud radar information.

Francis, Jennifer; Schweiger, Axel

2004-01-01

21

Comparison of AIRS, MODIS, CloudSat and CALIPSO cloud top height retrievals  

E-print Network

properties like cloud top height (CTH) is essential to understand their impact on the earth's radiation and Infrared Pathfinder Satellite Observation) satellites. Two cases containing a variety of cloud conditions have been studied, and the strengths/shortcomings of CTH products from infrared (IR) sounder radiances

Li, Jun

22

6.G Base and Height  

NSDL National Science Digital Library

This is a task from the Illustrative Mathematics website that is one part of a complete illustration of the standard to which it is aligned. Each task has at least one solution and some commentary that addresses important asects of the task and its potential use. Here are the first few lines of the commentary for this task: Mrs. Lito asked her students to label a base $b$ and its corresponding height $h$ in the triangle shown. Three students drew the figures below. Raul Ma...

23

Cloud Height Maps for Hurricanes Frances and Ivan  

NASA Technical Reports Server (NTRS)

NASA's Multi-angle Imaging SpectroRadiometer (MISR) captured these images and cloud-top height retrievals of Hurricane Frances on September 4, 2004, when the eye sat just off the coast of eastern Florida, and Hurricane Ivan on September 5th, after this cyclone had devastated Grenada and was heading toward the central and western Caribbean. Hurricane Frances made landfall in the early hours of September 5, and was downgraded to Tropical Storm status as it swept inland through the Florida panhandle and continued northward. On the heels of Frances is Hurricane Ivan, which is on record as the strongest tropical cyclone to form at such a low latitude in the Atlantic, and was the most powerful hurricane to have hit the Caribbean in nearly a decade.

The ability of forecasters to predict the intensity and amount of rainfall associated with hurricanes still requires improvement, especially on the 24 to 48 hour timescale vital for disaster planning. To improve the operational models used to make hurricane forecasts, scientists need to better understand the multi-scale interactions at the cloud, mesoscale and synoptic scales that lead to hurricane intensification and dissipation, and the various physical processes that affect hurricane intensity and rainfall distributions. Because these uncertainties with regard to how to represent cloud processes still exist, it is vital that the model findings be evaluated against hurricane observations whenever possible. Two-dimensional maps of cloud height such as those shown here offer an unprecedented opportunity for comparing simulated cloud fields against actual hurricane observations.

The left-hand panel in each image pair is a natural color view from MISR's nadir camera. The right-hand panels are cloud-top height retrievals produced by automated computer recognition of the distinctive spatial features between images acquired at different view angles. These results indicate that at the time that these images were acquired, clouds within Frances and Ivan had attained altitudes of 15 kilometers and 16 kilometers above sea level, respectively. The height fields pictured here are uncorrected for the effects of cloud motion. Wind-corrected heights (which have higher accuracy but sparser spatial coverage) are within about 1 kilometer of the heights shown here.

The Multi-angle Imaging SpectroRadiometer observes the daylit Earth continuously and every 9 days views the entire globe between 82o north and 82o south latitude. These data products were generated from a portion of the imagery acquired during Terra orbits 25081 and 25094. The panels cover an area of 380 kilometers x 924 kilometers, and utilize data from within blocks 65 to 87 within World Reference System-2 paths 14 and 222, respectively.

MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California In

2004-01-01

24

Cloud top height comparisons from ASTER, MISR, and MODIS for trade wind cumuli  

E-print Network

Cloud top height comparisons from ASTER, MISR, and MODIS for trade wind cumuli Iliana Genkova a ASTER stereo and ASTER infrared (IR) retrieved cloud top heights (CTHs) at 90 m spatial resolution height frequency distributions were derived for 41 trade wind cumulus cloud scenes with no cirrus

Zuidema, Paquita

25

Global Moderate Resolution Imaging Spectroradiometer (MODIS) cloud detection and height evaluation using CALIOP  

E-print Network

Global Moderate Resolution Imaging Spectroradiometer (MODIS) cloud detection and height evaluation detection and cloud top height (CTH) retrievals. Both CALIOP and MODIS are part of the NASA A for nonpolar daytime and the poorest agreement in the polar regions. Differences in cloud top heights depend

Sheridan, Jennifer

26

Cloud Coverage and Height Distribution from the GLAS Polar Orbiting Lidar: Comparison to Passive Cloud Retrievals  

NASA Technical Reports Server (NTRS)

The Geoscience Laser Altimeter System (GLAS) began full on orbit operations in September 2003. A main application of the two-wavelength GLAS lidar is highly accurate detection and profiling of global cloud cover. Initial analysis indicates that cloud and aerosol layers are consistently detected on a global basis to cross-sections down to 10(exp -6) per meter. Images of the lidar data dramatically and accurately show the vertical structure of cloud and aerosol to the limit of signal attenuation. The GLAS lidar has made the most accurate measurement of global cloud coverage and height to date. In addition to the calibrated lidar signal, GLAS data products include multi level boundaries and optical depth of all transmissive layers. Processing includes a multi-variable separation of cloud and aerosol layers. An initial application of the data results is to compare monthly cloud means from several months of GLAS observations in 2003 to existing cloud climatologies from other satellite measurement. In some cases direct comparison to passive cloud retrievals is possible. A limitation of the lidar measurements is nadir only sampling. However monthly means exhibit reasonably good global statistics and coverage results, at other than polar regions, compare well with other measurements but show significant differences in height distribution. For polar regions where passive cloud retrievals are problematic and where orbit track density is greatest, the GLAS results are particularly an advance in cloud cover information. Direct comparison to MODIS retrievals show a better than 90% agreement in cloud detection for daytime, but less than 60% at night. Height retrievals are in much less agreement. GLAS is a part of the NASA EOS project and data products are thus openly available to the science community (see http://glo.gsfc.nasa.gov).

Spinhime, J. D.; Palm, S. P.; Hlavka, D. L.; Hart, W. D.; Mahesh, A.

2004-01-01

27

Cloud Height Estimation with a Single Digital Camera and Artificial Neural Networks  

NASA Astrophysics Data System (ADS)

Clouds influence the local weather, the global climate and are an important parameter in the weather prediction models. Clouds are also an essential component of airplane safety when visual flight rules (VFR) are enforced, such as in most small aerodromes where it is not economically viable to install instruments for assisted flying. Therefore it is important to develop low cost and robust systems that can be easily deployed in the field, enabling large scale acquisition of cloud parameters. Recently, the authors developed a low-cost system for the measurement of cloud base height using stereo-vision and digital photography. However, due to the stereo nature of the system, some challenges were presented. In particular, the relative camera orientation requires calibration and the two cameras need to be synchronized so that the photos from both cameras are acquired simultaneously. In this work we present a new system that estimates the cloud height between 1000 and 5000 meters. This prototype is composed by one digital camera controlled by a Raspberry Pi and is installed at Centro de Geofísica de Évora (CGE) in Évora, Portugal. The camera is periodically triggered to acquire images of the overhead sky and the photos are downloaded to the Raspberry Pi which forwards them to a central computer that processes the images and estimates the cloud height in real time. To estimate the cloud height using just one image requires a computer model that is able to learn from previous experiences and execute pattern recognition. The model proposed in this work is an Artificial Neural Network (ANN) that was previously trained with cloud features at different heights. The chosen Artificial Neural Network is a three-layer network, with six parameters in the input layer, 12 neurons in the hidden intermediate layer, and an output layer with only one output. The six input parameters are the average intensity values and the intensity standard deviation of each RGB channel. The output parameter in the output layer is the cloud height estimated by the ANN. The training procedure was performed, using the back-propagation method, in a set of 260 different clouds with heights in the range [1000, 5000] m. The training of the ANN has resulted in a correlation ratio of 0.74. This trained ANN can therefore be used to estimate the cloud height. The previously described system can also measure the wind speed and direction at cloud height by measuring the displacement, in pixels, of a cloud feature between consecutively acquired photos. Also, the geographical north direction can be estimated using this setup through sequential night images with high exposure times. A further advantage of this single camera system is that no camera calibration or synchronization is needed. This significantly reduces the cost and complexity of field deployment of cloud height measurement systems based on digital photography.

Carretas, Filipe; Janeiro, Fernando M.

2014-05-01

28

Deep Convective Cloud Top Heights and Their Thermodynamic Control During CRYSTAL-FACE  

NASA Technical Reports Server (NTRS)

Infrared (11 micron) radiances from GOES-8 and local radiosonde profiles, collected during the Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment (CRYSTAL-FACE) in July 2002, are used to assess the vertical distribution of Florida-area deep convective cloud top height and test predictions as to its variation based on parcel theory. The highest infrared tops (Z(sub 11)) reached approximately to the cold point, though there is at least a 1-km uncertainty due to unknown cloud-environment temperature differences. Since lidar shows that visible 'tops' are 1 km or more above Z(sub 11), visible cloud tops frequently penetrated the lapse-rate tropopause (approx. 15 km). Further, since lofted ice content may be present up to approx. 1 km above the visible tops, lofting of moisture through the mean cold point (15.4 km) was probably common. Morning clouds, and those near Key West, rarely penetrated the tropopause. Non-entraining parcel theory (i.e., CAPE) does not successfully explain either of these results, but can explain some of the day-to-day variations in cloud top height over the peninsula. Further, moisture variations above the boundary layer account for most of the day-today variability not explained by CAPE, especially over the oceans. In all locations, a 20% increase in mean mixing ratio between 750 and 500 hPa was associated with about 1 km deeper maximum cloud penetration relative to the neutral level. These results suggest that parcel theory may be useful for predicting changes in cumulus cloud height over time, but that parcel entrainment must be taken into account even for the tallest clouds. Accordingly, relative humidity above the boundary layer may exert some control on the height of the tropical troposphere.

Sherwood, Steven C.; Minnis, Patrick; McGill, Matthew

2004-01-01

29

A Simple Stochastic Model for Generating Broken Cloud Optical Depth and Top Height Fields  

NASA Technical Reports Server (NTRS)

A simple and fast algorithm for generating two correlated stochastic twodimensional (2D) cloud fields is described. The algorithm is illustrated with two broken cumulus cloud fields: cloud optical depth and cloud top height retrieved from Moderate Resolution Imaging Spectrometer (MODIS). Only two 2D fields are required as an input. The algorithm output is statistical realizations of these two fields with approximately the same correlation and joint distribution functions as the original ones. The major assumption of the algorithm is statistical isotropy of the fields. In contrast to fractals and the Fourier filtering methods frequently used for stochastic cloud modeling, the proposed method is based on spectral models of homogeneous random fields. For keeping the same probability density function as the (first) original field, the method of inverse distribution function is used. When the spatial distribution of the first field has been generated, a realization of the correlated second field is simulated using a conditional distribution matrix. This paper is served as a theoretical justification to the publicly available software that has been recently released by the authors and can be freely downloaded from http://i3rc.gsfc.nasa.gov/Public codes clouds.htm. Though 2D rather than full 3D, stochastic realizations of two correlated cloud fields that mimic statistics of given fields have proved to be very useful to study 3D radiative transfer features of broken cumulus clouds for better understanding of shortwave radiation and interpretation of the remote sensing retrievals.

Prigarin, Sergei M.; Marshak, Alexander

2007-01-01

30

Automatic cloud top height determination in mountainous areas using a cost-effective time-lapse camera system  

NASA Astrophysics Data System (ADS)

A new method is presented for the determination of cloud top heights using the footage of a time-lapse camera that is placed above a frequently occurring cloud layer in a mountain valley. Contact points between cloud tops and underlying terrain are automatically detected in the camera image based on differences in the brightness, texture and movement of cloudy and non-cloudy areas. The height of the detected cloud top positions is determined by comparison with a digital elevation model projected to the view of the camera. The technique has been validated using data about the cloud immersion of a second camera as well as via visual assessment. The validation shows a high detection quality, especially regarding the requirements for the validation of satellite cloud top retrieval algorithms.

Schulz, H. M.; Chang, S.-C.; Thies, B.; Bendix, J.

2014-12-01

31

Temporal variation of the cloud top height over the tropical Pacific observed by geostationary satellites  

NASA Astrophysics Data System (ADS)

Stratiform clouds (nimbostratus and cirriform clouds) in the upper troposphere accompanied with cumulonimbus activity cover large part of the tropical region and largely affect the radiation and water vapor budgets there. Recently new satellites (CloudSat and CALIPSO) can give us the information of cloud height and cloud ice amount even over the open ocean. However, their coverage is limited just below the satellite paths; it is difficult to capture the whole shape and to trace the lifecycle of each cloud system by using just these datasets. We made, as a complementary product, a dataset of cloud top height and visible optical thickness with one-hour resolution over the wide region, by using infrared split-window data of the geostationary satellites (AGU fall meeting 2011) and released on the internet (http://database.rish.kyoto-u.ac.jp/arch/ctop/). We made lookup tables for estimating cloud top height only with geostationary infrared observations by comparing them with the direct cloud observation by CloudSat (Hamada and Nishi, 2010, JAMC). We picked out the same-time observations by MTSAT and CloudSat and regressed the cloud top height observation of CloudSat back onto 11?m brightness temperature (Tb) and the difference between the 11?m Tb and 12?m Tb. We will call our estimated cloud top height as "CTOP" below. The area of our coverage is 85E-155W (MTSAT2) and 80E-160W(MTSAT1R), and 20S-20N. The accuracy of the estimation with the IR split-window observation is the best in the upper tropospheric height range. We analyzed the formation and maintenance of the cloud systems whose top height is in the upper troposphere with our CTOP analysis, CloudSat 2B-GEOPROF, and GSMaP (Global Satellite Mapping of Precipitation) precipitation data. Most of the upper tropospheric stratiform clouds have their cloud top within 13-15 km range. The cloud top height decreases slowly when dissipating but still has high value to the end. However, we sometimes observe that a little lower cloud top height (6-10 km) is kept within one-two days. A typical example is observed on 5 January 2011 in a dissipating cloud system with 1000-km scale. This cluster located between 0-10N just west of the International Date Line and moved westward with keeping relatively lower cloud top (6-10 km) over one day. This top height is lower than the ubiquitous upper-tropospheric stratiform clouds but higher than the so-called 'congestus cloud' whose top height is around 0C. CloudSat data show the presence of convective rainfall. It suggests that this cloud system continuously kept making new anvil clouds in a little lower height than usual. We examined the seasonal variation of the distribution of cloud systems with a little lower cloud top height (6-11 km) during 2010-11. The number of such cloud systems is not constant with seasons but frequently increased in some specific seasons. Over the equatorial ocean region (east of 150E), they were frequently observed during the northern winter.

Nishi, N.; Hamada, A.

2012-12-01

32

Altimeter height measurement errors introduced by the presence of variable cloud and rain attenuation  

NASA Technical Reports Server (NTRS)

It has recently been recognized that spatially inhomogeneous clouds and rain can substantially affect the height precision obtainable from a spaceborne radar altimeter system. Through computer simulation, it has been found that typical levels of cloud and rain intensities and associated spatial variabilities may degrade altimeter precision at 13.5 GHz and, in particular, cause severe degradation at 35 GHz. This degradation in precision is a result of radar signature distortion caused by variable attenuation over the beam limited altimeter footprint. Because attenuation effects increase with frequency, imprecision caused by them will significantly impact on the frequency selection of future altimeters. In this paper the degradation of altimeter precision introduced by idealized cloud and rain configurations as well as for a realistic rain configuration as measured with a ground based radar is examined.

Monaldo, F. M.; Goldhirsh, J.; Walsh, E. J.

1984-01-01

33

Altimeter height measurement error introduced by the presence of variable cloud and rain attenuation  

NASA Technical Reports Server (NTRS)

It has recently been recognized that spatially inhomogeneous clouds and rain can substantially affect the height precision obtainable from a spaceborne radar altimeter system. Through computer simulation, it has been found that typical levels of cloud and rain intensities and associated spatial variabilities may degrade altimeter precision at 13.5 GHz and, in particular, cause severe degradation at 35 GHz. This degradation in precision is a result of radar signature distortion caused by variable attenuation over the beam limited altimeter footprint. Because attenuation effects increase with frequency, imprecision caused by them will significantly impact on the frequency selection of future altimeters. In this paper the degradation of altimeter precision introduced by idealized cloud and rain configurations as well as for a realistic rain configuration as measured with a ground based radar is examined.

Monaldo, F. M.; Goldhirsh, J.; Walsh, E. J.

1986-01-01

34

An Assessment of Factors Limiting Tropical Congestus Cloud-Top Heights  

E-print Network

, creating a mode of cloud-top heights at the stable layer as clouds lose buoyancy. The signal for lapse rate changes in the AIRS data, however, is not as strong as the signal for RH differences. Near 600-400 hPa, roughly the region where congestus cloud...

Casey, Sean P.

2010-07-14

35

Global Moderate Resolution Imaging Spectroradiometer (MODIS) cloud detection and height evaluation using CALIOP  

Microsoft Academic Search

A global 2-month comparison is presented between the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and the Moderate Resolution Imaging Spectroradiometer (MODIS) for both cloud detection and cloud top height (CTH) retrievals. Both CALIOP and MODIS are part of the NASA A-Train constellation of satellites and provide continuous near-coincident measurements that result in over 28 million cloud detection comparisons and over

R. E. Holz; S. A. Ackerman; F. W. Nagle; R. Frey; S. Dutcher; R. E. Kuehn; M. A. Vaughan; B. Baum

2008-01-01

36

Ship-based observation of drizzling stratocumulus clouds from EPIC to VOCALS Simon P. de Szoeke, Oregon State University, Corvallis, OR.  

E-print Network

and cloud top height increase toward the west by ~300m over 10° longitude, while cloud thickness is nearly measured cloud base height and temporal cloud fraction. Radar wind profilers retrieved inversion height, and mixing layer height observations below the cloud. Seven years measuring marine stratocumulus

Parker, Matthew D. Brown

37

A comparison of cloud top heights computed from airborne lidar and MAS radiance data using CO2 slicing  

E-print Network

A comparison of cloud top heights computed from airborne lidar and MAS radiance data using CO2]. Other studies have compared CO2- slicing cloud heights with those computed from lidar data [Smith in assessing the accuracy of the CO2-slicing cloud height algorithm. Infrared measurements of upwelling

Sheridan, Jennifer

38

Stereographic cloud heights from the imagery of two scan-synchronized geostationary satellites  

NASA Technical Reports Server (NTRS)

Scan synchronization of the sensors of two SMS-GOES satellites yields imagery from which cloud heights can be derived stereographically with a theoretical two-sigma random uncertainty of + or - 0.25 km for pairs of satellites separated by 60 degrees of longitude. Systematic height errors due to cloud motion can be kept below 100 m for all clouds with east-west components of speed below hurricane speed, provided the scan synchronization is within 40 seconds at the mid-point latitude, and the spin axis of each satellite is parallel to that of the earth.

Minzner, R. A.; Teagle, R. D.; Steranka, J.; Shenk, W. E.

1979-01-01

39

Fluctuations of high clouds and 500-mb geopotential heights in baroclinic waveguides  

NASA Technical Reports Server (NTRS)

The spatial phase relationship between the atmospheric circulation and the bandpass fluctuations in cloudiness are investigated using satellite retrievals of high cloud areas reported by Stowe et al. (1988, 1989) NMC 500-mb geopotential heights in northern extratropics. Results of the analysis suggest that the high-cloud structures of baroclinic waves are less spatially coherent than the internal geopotential-height structures. It is shown that over the North Pacific, small-scale (latitudinal wavenumber 13-18) fluctuations in geopotential play a greater role in forcing high cloudiness than do medium-scale (latitudinal wavenumber 7-12) fluctuations in geopotential.

Charlock, Thomas P.; Rose, Fred G.

1991-01-01

40

Satellite and Surface Data Synergy for Developing a 3D Cloud Structure and Properties Characterization Over the ARM SGP. Stage 1: Cloud Amounts, Optical Depths, and Cloud Heights Reconciliation  

NASA Technical Reports Server (NTRS)

One of the primary Atmospheric Radiation Measurement (ARM) Program objectives is to obtain measurements applicable to the development of models for better understanding of radiative processes in the atmosphere. We address this goal by building a three-dimensional (3D) characterization of the cloud structure and properties over the ARM Southern Great Plains (SGP). We take the approach of juxtaposing the cloud properties as retrieved from independent satellite and ground-based retrievals, and looking at the statistics of the cloud field properties. Once these retrievals are well understood, they will be used to populate the 3D characterization database. As a first step we determine the relationship between surface fractional sky cover and satellite viewing angle dependent cloud fraction (CF). We elaborate on the agreement intercomparing optical depth (OD) datasets from satellite and ground using available retrieval algorithms with relation to the CF, cloud height, multi-layer cloud presence, and solar zenith angle (SZA). For the SGP Central Facility, where output from the active remote sensing cloud layer (ARSCL) valueadded product (VAP) is available, we study the uncertainty of satellite estimated cloud heights and evaluate the impact of this uncertainty for radiative studies.

Genkova, I.; Long, C. N.; Heck, P. W.; Minnis, P.

2003-01-01

41

Cloud Based Applications and Platforms (Presentation)  

SciTech Connect

Presentation to the Cloud Computing East 2014 Conference, where we are highlighting our cloud computing strategy, describing the platforms on the cloud (including Smartgrid.gov), and defining our process for implementing cloud based applications.

Brodt-Giles, D.

2014-05-15

42

Texture-based cloud classification  

NASA Technical Reports Server (NTRS)

The purpose of the 1988 ASEE Summer Program has been to broaden the application of texture-based cloud classification approaches to lower spatial resolution GOES imagery, and to design texture-based approaches for determining cloud cover over high albedo surfaces.

Welch, Ronald M.

1988-01-01

43

Accuracy analysis of height difference models derived from terrestrial laser scanning point clouds  

NASA Astrophysics Data System (ADS)

In many research areas the temporal development of the earth surface topography is investigated for geomorphological analysis (e.g. landslide monitoring). Terrestrial laser scanning (TLS) often is used for this purpose, as it allows a fast and detailed 3d reconstruction of the sampled object. The temporal development of the earth surface usually is investigated on the basis of rasterized data, i.e. digital terrain models (DTM). The difference between two DTMs - the difference model - should preferably correspond to the terrain height changes occurred between the measurement campaigns. Actually, these height differences can be influenced by numerous potential error sources. The height accuracy of each raster cell is affected primarily by (a) the measurement accuracy of the deployed TLS, (b) the terrain topography (e.g. roughness), (c) the registration accuracy, (d) the georeferencing accuracy and (e) the raster interpolation method. Thus, in this contribution, height differences are treated as stochastic variables in order to estimate their precision. For an accurate estimation of the height difference precision a detailed knowledge about the whole processing pipeline (from the raw point clouds to the final difference model) is essential. In this study, first the height difference precision is estimated by a rigorous error propagation. As main result, for each raster cell of the difference model, a corresponding height error is estimated, forming an error map. A statistical hypothesis test is presented in order to judge the significance of a height difference. Furthermore, in order to asses the effect of single factors on the final height difference precision, multivariate statistic methods are applied. This analysis allows the deduction of a simple error propagation model, neglecting error sources with small impact on the final precision. The proposed method is demonstrated by means of TLS data acquired at the Gepatschferner (Tyrol, Austria). This study was carried out within the research project PROSA (high-resolution measurements of morphodynamics in rapidly changing PROglacial Systems of the Alps).

Glira, Philipp; Briese, Christian; Pfeifer, Norbert; Dusik, Jana; Hilger, Ludwig; Neugirg, Fabian; Baewert, Henning

2014-05-01

44

A comparison of cloud top heights computed from airborne lidar and MAS radiance data using CO 2 slicing  

Microsoft Academic Search

Data from two instruments onboard the National Aeronautics and Space Administration (NASA) ER-2 high-altitude aircraft have been utilized in the largest validation study to date in assessing the accuracy of the CO2-slicing cloud height algorithm. Infrared measurements of upwelling radiance from the MODIS (Moderate- Resolution Imaging Spectroradiometer) airborne simulator (MAS) were used to generate cloud top heights and then compared

Richard A. Frey; Bryan A. Baum; W. Paul Menzel; Steven A. Ackerman; Christopher C. Moeller; James D. Spinhirne

1999-01-01

45

Linear trends in cloud top height from passive observations in the oxygen A-band  

NASA Astrophysics Data System (ADS)

Measurements by the hyperspectral spectrometers GOME, SCIAMACHY and GOME-2 are used to determine the rate of linear change (and trends) in cloud top height (CTH) in the period between June 1996 and May 2012. The retrievals are obtained from Top-Of-Atmosphere (TOA) backscattered solar light in the oxygen A-band using the Semi-Analytical CloUd Retrieval Algorithm SACURA. The physical framework relies on the asymptotic equations of radiative transfer, valid for optically thick clouds. Using linear least-squares techniques, a global trend of -1.78 ± 2.14 m yr-1 in deseasonalized CTH has been found, in the latitude belt within ±60°, with diverging tendencies over land (+0.27 ± 3.2 m yr-1) and ocean (-2.51 ± 2.8 m yr-1). The El Niño-Southern Oscillation (ENSO), strongly coupled to CTH, forces clouds to lower altitudes. The global ENSO-corrected trend in CTH amounts to -0.49 ± 2.22 m yr-1. At a global scale, no explicit regional pattern of statistically significant trends (at 95% confidence level, estimated with bootstrap technique) have been found, which would be representative of typical natural synoptical features. One exception is North Africa, which exhibits the strongest upward trend in CTH sustained by an increasing trend in water vapour.

Lelli, L.; Kokhanovsky, A. A.; Rozanov, V. V.; Vountas, M.; Burrows, J. P.

2014-06-01

46

Satellite retrieval of convective cloud base temperature based on the NPP/VIIRS Imager  

NASA Astrophysics Data System (ADS)

advent of the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the Suomi National Polar-Orbiting Partnership (NPP) satellite provided a quantum jump in the satellite capabilities of retrieving cloud properties, because it nearly tripled the resolution in the thermal channels (375 m). This allowed us to develop a methodology for retrieving convective cloud base temperature (Tb) and validate it over the Atmospheric System Research Southern Great Plains site for the satellite early afternoon overpass time. The standard error of the Tb retrieval was only 1.1°C. The knowledge of Tb allows the calculation of cloud base height and the depth of the boundary layer, as well as the boundary layer water vapor mixing ratio with an accuracy of about 10%. The feasibility of retrieving cloud base temperature and height is an essential component that is required for retrieving cloud condensation nuclei (CCN) from satellites by using convective clouds as natural CCN chambers.

Zhu, Yannian; Rosenfeld, Daniel; Yu, Xing; Liu, Guihua; Dai, Jin; Xu, Xiaohong

2014-02-01

47

Cloud Condensation Nuclei Retrievals at Cloud Base in North Dakota  

E-print Network

Cloud Condensation Nuclei Retrievals at Cloud Base in North Dakota · Mariusz Starzec #12;Motivation Compare University of Wyoming (UWyo) and Droplet Measurement Technologies (DMT) cloud condensation nuclei condensation nuclei concentration (CCNC) at any supersaturation (SS) #12;Background Aerosols act as nuclei

Delene, David J.

48

A physically based algorithm for non-blackbody correction of the cloud top temperature for the convective clouds  

NASA Astrophysics Data System (ADS)

Cloud top temperature is a key parameter to retrieval in the remote sensing of convective clouds. Passive remote sensing cannot directly measure the temperature at the cloud tops. Here we explore a synergistic way of estimating cloud top temperature by making use of the simultaneous passive and active remote sensing of clouds (in this case, CloudSat and MODIS). Weighting function of the MODIS 11?m band is explicitly calculated by feeding cloud hydrometer profiles from CloudSat retrievals and temperature and humidity profiles based on ECMWF ERA-interim reanalysis into a radiation transfer model. Among 19,699 tropical deep convective clouds observed by the CloudSat in 2008, the averaged effective emission level (EEL, where the weighting function attains its maximum) is at optical depth 0.91 with a standard deviation of 0.33. Furthermore, the vertical gradient of CloudSat radar reflectivity, an indicator of the fuzziness of convective cloud top, is linearly proportional to, d_{CTH-EEL}, the distance between the EEL of 11?m channel and cloud top height (CTH) determined by the CloudSat when d_{CTH-EEL}<0.6km. Beyond 0.6km, the distance has little sensitivity to the vertical gradient of CloudSat radar reflectivity. Based on these findings, we derive a formula between the fuzziness in the cloud top region, which is measurable by CloudSat, and the MODIS 11?m brightness temperature assuming that the difference between effective emission temperature and the 11?m brightness temperature is proportional to the cloud top fuzziness. This formula is verified using the simulated deep convective cloud profiles by the Goddard Cumulus Ensemble model. We further discuss the application of this formula in estimating cloud top buoyancy as well as the error characteristics of the radiative calculation within such deep-convective clouds.

Wang, C.; Luo, Z. J.; Chen, X.; Zeng, X.; Tao, W.; Huang, X.

2012-12-01

49

Estimating plot-level tree heights with lidar: local filtering with a canopy-height based variable  

E-print Network

Estimating plot-level tree heights with lidar: local filtering with a canopy-height based variable algorithms for deriving the terrain model and estimating tree heights by using a multiple return, high were: (1) to develop and test algorithms to estimate plot level tree height using lidar data, and (2

50

Cloud-Based Data Storage  

ERIC Educational Resources Information Center

The vulnerability and inefficiency of backing up data on-site is prompting school districts to switch to more secure, less troublesome cloud-based options. District auditors are pushing for a better way to back up their data than the on-site, tape-based system that had been used for years. About three years ago, Hendrick School District in…

Waters, John K.

2011-01-01

51

Novel Spectrograph/Radiometer for Cloud Top Height Measurement Using Three Complementary Techniques  

NASA Technical Reports Server (NTRS)

A proof-of-concept (POC) instrument system to measure cloud top height from space using three complementary techniques is presented. These techniques use measurements of: (1) thermal infrared (IR); (2) molecular oxygen 'A' band absorption; and (3) filling-in of Fraunhofer lines (the Ring effect), respectively. Combining three techniques is achieved with a single grating spectrograph with bandpass and order sorting filters by measuring I I jim radiation from the zeroth order of the grating for the IR, 750-780 nm radiation from the first order for the 'A' band absorption, and 390-400 mn radiation from the second order for the Ca K and H Fraunhofer line filling-in effect. The POC system and its measurement results with the POC system are described.

Park, Hongwoo; Soulen, Peter F.; Prasad, Coorg R.

1997-01-01

52

Height Distribution Between Cloud and Aerosol Layers from the GLAS Spaceborne Lidar in the Indian Ocean Region  

NASA Technical Reports Server (NTRS)

The Geoscience Laser Altimeter System (GLAS), a nadir pointing lidar on the Ice Cloud and land Elevation Satellite (ICESat) launched in 2003, now provides important new global measurements of the relationship between the height distribution of cloud and aerosol layers. GLAS data have the capability to detect, locate, and distinguish between cloud and aerosol layers in the atmosphere up to 40 km altitude. The data product algorithm tests the product of the maximum attenuated backscatter coefficient b'(r) and the vertical gradient of b'(r) within a layer against a predetermined threshold. An initial case result for the critical Indian Ocean region is presented. From the results the relative height distribution between collocated aerosol and cloud shows extensive regions where cloud formation is well within dense aerosol scattering layers at the surface. Citation: Hart, W. D., J. D. Spinhime, S. P. Palm, and D. L. Hlavka (2005), Height distribution between cloud and aerosol layers from the GLAS spaceborne lidar in the Indian Ocean region,

Hart, William D.; Spinhirne, James D.; Palm, Steven P.; Hlavka, Dennis L.

2005-01-01

53

Study on the cloud layer height and properties in Hefei observed by lidar  

NASA Astrophysics Data System (ADS)

A co-axial transmission elastic-backscattered lidar aiming to detect the optical properties of the clouds is presented in this paper. The modular co-axial design can guarantee the consistency of the transmitting part and the receiving part. In practice a specific diaphragm is used to suppress the stray light of the primary mirror and background light to improve SNR of the backscattered signal in the daytime. So the near ground signal must be corrected with the appropriate overlap factor. A Licel transient recorder is used for data acquisition in analog and photon counting combined in one acquisition system. With the 15 MHz sampling rate, the spatial resolution of 10 m can be attained. The control over the transient recorder and the treatment of the data is performed on a PC. After getting the correctional backscattered signal, retrieving and analyzing the extinction coefficient profile, the cloud base, cloud peak and related optical parameters of the clouds can be confirmed. In order to testify the feasibility of our lidar, it was implemented with a Finland ceilometer Vaisala simultaneously in May in 2008 in Hefei. Results show the lidar system is stable and the data is reliable.

Chen, Zhenyi; Liu, Wenqing; Zhang, Yujun; He, Junfeng; Ruan, Jun; Li, Sheng; Cui, Yiben

2010-10-01

54

Height estimations based on eye measurements throughout a gait cycle.  

PubMed

Anthropometric measurements (e.g. the height to the head, nose tip, eyes or shoulders) of a perpetrator based on video material may be used in criminal cases. However, several height measurements may be difficult to assess as the perpetrators may be disguised by clothes or headwear. The eye height (EH) measurement, on the other hand, is less prone to concealment. The purpose of the present study was to investigate: (1) how the eye height varies during the gait cycle, and (2) how the eye height changes with head position. The eyes were plotted manually in APAS for 16 test subjects during a complete gait cycle. The influence of head tilt on the EH was investigated in 20 healthy men. Markers were attached to the face and the subjects were instructed to stand relaxed, tilt their head to the right, to the left, forward and backward. The marker data for the right eye were used to calculate the EH. The respective deviation and SD from the relaxed standing EH and the EH in the Frankfurt plane, left tilted, right tilted, forward tilted and backward tilted, in addition to the corresponding head tilt angles were calculated. There was no correlation between the height of the subject and the maximum vertical displacement of the EH throughout the gait cycle nor between height of the subjects and the variation of the EH throughout the gait cycle. The average maximum vertical displacement for the test subject group was 4.76 cm (± 1.56 cm). The average EH was lower when the subjects were standing in the relaxed position than in the Frankfurt plane. The average EH was higher in the relaxed position than when the subjects tilted their heads, except when they tilted their heads backwards. The subjects had a slightly larger range of motion to the right than to the left, which was not significant. The results of this study provide a range for eye height estimates and may be readily implemented in forensic case work. It can be used as a reference in height estimates in cases with height measurements based on time of the gait cycle and based on the degree of head tilt from video material. Our data also provide descriptive statistics which may be helpful when comparing eye height measurements of a perpetrator with one or more suspects. PMID:24503163

Yang, Sylvia X M; Larsen, Peter K; Alkjær, Tine; Juul-Kristensen, Birgit; Simonsen, Erik B; Lynnerup, Niels

2014-03-01

55

Convective cloud heights as a diagnostic for methane environment on Titan Erika L. Barth *, Scot C.R. Rafkin  

E-print Network

Convective cloud heights as a diagnostic for methane environment on Titan Erika L. Barth *, Scot C t i c l e i n f o Article history: Received 12 June 2008 Revised 5 December 2008 Accepted 19 January 2009 Available online xxxx Keywords: Titan Atmospheres Structure a b s t r a c t The appearance

Rafkin, Scot C. R.

56

CSc-165 Spring 2014 Week 9(a) Image-Based Height Maps  

E-print Network

CSc-165 Spring 2014 Week 9(a) Image-Based Height Maps (based on code example 4[b]) public class myGame extends BaseGame { . . . private void initTerrain() { // create height map and terrain block ImageBasedHeightMap myHeightMap = new ImageBasedHeightMap("height.jpg"); TerrainBlock imageTerrain = createTerBlock(myHeight

Gordon, Scott

57

Thin and thick cloud top height retrieval algorithm with the Infrared Camera and LIDAR of the JEM-EUSO Space Mission  

E-print Network

The origin of cosmic rays have remained a mistery for more than a century. JEM-EUSO is a pioneer space-based telescope that will be located at the International Space Station (ISS) and its aim is to detect Ultra High Energy Cosmic Rays (UHECR) and Extremely High Energy Cosmic Rays (EHECR) by observing the atmosphere. Unlike ground-based telescopes, JEM-EUSO will observe from upwards, and therefore, for a properly UHECR reconstruction under cloudy conditions, a key element of JEM-EUSO is an Atmospheric Monitoring System (AMS). This AMS consists of a space qualified bi-spectral Infrared Camera, that will provide the cloud coverage and cloud top height in the JEM-EUSO Field of View (FoV) and a LIDAR, that will measure the atmospheric optical depth in the direction it has been shot. In this paper we will explain the effects of clouds for the determination of the UHECR arrival direction. Moreover, since the cloud top height retrieval is crucial to analyze the UHECR and EHECR events under cloudy conditions, the ret...

Sáez-Cano, G; del Peral, L; Neronov, A; Wada, S; Frías, M D Rodríguez

2015-01-01

58

Integration of Satellite-Derived Cloud Phase, Cloud Top Height, and Liquid Water Path into an Operational Aircraft Icing Nowcasting System  

NASA Technical Reports Server (NTRS)

Operational products used by the U.S. Federal Aviation Administration to alert pilots of hazardous icing provide nowcast and short-term forecast estimates of the potential for the presence of supercooled liquid water and supercooled large droplets. The Current Icing Product (CIP) system employs basic satellite-derived information, including a cloud mask and cloud top temperature estimates, together with multiple other data sources to produce a gridded, three-dimensional, hourly depiction of icing probability and severity. Advanced satellite-derived cloud products developed at the NASA Langley Research Center (LaRC) provide a more detailed description of cloud properties (primarily at cloud top) compared to the basic satellite-derived information used currently in CIP. Cloud hydrometeor phase, liquid water path, cloud effective temperature, and cloud top height as estimated by the LaRC algorithms are into the CIP fuzzy logic scheme and a confidence value is determined. Examples of CIP products before and after the integration of the LaRC satellite-derived products will be presented at the conference.

Haggerty, Julie; McDonough, Frank; Black, Jennifer; Landott, Scott; Wolff, Cory; Mueller, Steven; Minnis, Patrick; Smith, William, Jr.

2008-01-01

59

Satellite-Based Insights into Precipitation Formation Processes in Continental and Maritime Convective Clouds  

Microsoft Academic Search

Multispectral analyses of satellite images are used to calculate the evolution of the effective radius of convective cloud particles with temperature, and to infer from that information about precipitation forming processes in theclouds. Different microphysical processes are identified at different heights. From cloud base to top, the microphysical classification includes zones of diffusional droplet growth, coalescence droplet growth, rainout, mixed-phase

Daniel Rosenfeld; Itamar M. Lensky

1998-01-01

60

Satellite-Observed Location of Stratocumulus Cloud-Top Heights in the Presence of Strong Inversions  

Microsoft Academic Search

Infrared channels on the Moderate Resolution Imaging Spectroradiometer (MODIS) are used to infer cloud-top pressure (CTP), temperature, and effective cloud amount or emissivity. For low clouds, those with tops at pressures greater than 700 hPa, the infrared window 11-mum channel brightness temperature is used to determine the CTP and the corresponding cloud-top temperature by comparison with the temperature profile obtained

Harshvardhan; Guangyu Zhao; Larry Di Girolamo; Robert N. Green

2009-01-01

61

Validation of Satellite-Based Objective Overshooting Cloud-Top Detection Methods Using CloudSat Cloud Profiling Radar Observations  

NASA Technical Reports Server (NTRS)

Two satellite infrared-based overshooting convective cloud-top (OT) detection methods have recently been described in the literature: 1) the 11-mm infrared window channel texture (IRW texture) method, which uses IRW channel brightness temperature (BT) spatial gradients and thresholds, and 2) the water vapor minus IRW BT difference (WV-IRW BTD). While both methods show good performance in published case study examples, it is important to quantitatively validate these methods relative to overshooting top events across the globe. Unfortunately, no overshooting top database currently exists that could be used in such study. This study examines National Aeronautics and Space Administration CloudSat Cloud Profiling Radar data to develop an OT detection validation database that is used to evaluate the IRW-texture and WV-IRW BTD OT detection methods. CloudSat data were manually examined over a 1.5-yr period to identify cases in which the cloud top penetrates above the tropopause height defined by a numerical weather prediction model and the surrounding cirrus anvil cloud top, producing 111 confirmed overshooting top events. When applied to Moderate Resolution Imaging Spectroradiometer (MODIS)-based Geostationary Operational Environmental Satellite-R Series (GOES-R) Advanced Baseline Imager proxy data, the IRW-texture (WV-IRW BTD) method offered a 76% (96%) probability of OT detection (POD) and 16% (81%) false-alarm ratio. Case study examples show that WV-IRW BTD.0 K identifies much of the deep convective cloud top, while the IRW-texture method focuses only on regions with a spatial scale near that of commonly observed OTs. The POD decreases by 20% when IRW-texture is applied to current geostationary imager data, highlighting the importance of imager spatial resolution for observing and detecting OT regions.

Bedka, Kristopher M.; Dworak, Richard; Brunner, Jason; Feltz, Wayne

2012-01-01

62

CLOUD HEIGHT DETERMINATION AND COMPARISON WITH OBSERVED RAINFALL BY USING METEOSAT SECOND GENERATION (MSG) IMAGERIES  

Microsoft Academic Search

To obtain accurate estimates of surface and cloud parameters from satellite data an algorithm has to be developed which identifies cloud-free and cloud-contaminated pixels. Data from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) on board Meteosat Second Generation (MSG) satellites have been available since February 2004. The data is accessible to National Meteorological and Hydrological Services (NMHSs). This study

Peter S. Masika

63

Research on multiple attribute evaluation method based on cloud model  

Microsoft Academic Search

A cloud model-based multiple attribute evaluation method is put forward. The ways of the cloud transformation is used to represent the cloud model of each different attribute. On the base of one-dimension cloud, the multidimensional cloud model of system is confirmed. And then, evaluation value is achieved by calculating the deviation degree of the system cloud gravity center from the

Guo Rong-xiao; Xia Jing-bo; Zhang Li; Qian Yuan

2010-01-01

64

CloudAnalyst: A CloudSim-based Visual Modeller for Analysing Cloud Computing Environments and Applications  

E-print Network

CloudAnalyst: A CloudSim-based Visual Modeller for Analysing Cloud Computing Environments and Applications Bhathiya Wickremasinghe1 , Rodrigo N. Calheiros2 , and Rajkumar Buyya1 1 The Cloud Computing and Distributed Systems (CLOUDS) Laboratory Department of Computer Science and Software Engineering The University

Buyya, Rajkumar

65

Comparison of CERES-MODIS stratus cloud properties with ground-based measurements at the DOE ARM Southern Great Plains site  

E-print Network

Comparison of CERES-MODIS stratus cloud properties with ground- based measurements at the DOE ARM. [1] Overcast stratus cloud properties derived for the Clouds and the Earth's Radiant Energy System stratus decks and a subset, single- layered unbroken decks (SL). The CERES-MODIS effective cloud heights

Dong, Xiquan

66

Low altitude cloud height and methane humidity retrievals on Titan in the near-IR  

NASA Astrophysics Data System (ADS)

The formation of low altitude clouds on Titan, with cloud-top altitudes below ~10km, likely occurs by a fundamentally different mechanism than for the clouds commonly observed to have cloud-tops in the upper troposphere, above ~15km [1]. Near-infrared spectroscopy of clouds has been the method of choice for determining cloud altitudes [2], however, uncertainties in aerosols scattering properties and opacities, together with limitations in laboratory measurements of gas opacities (in particular for methane), lead to uncertainties in how accurately the altitude of low clouds can be retrieved [3]. Here we revisit near-IR spectra obtained with Keck and Cassini using new laboratory methane line data in the HITRAN 2012 database [4] to address the problem of measuring the altitudes of low clouds. We discuss the role of topography in relation to the formation of low clouds and other diagnostics of conditions near the surface, such as the tropospheric methane humidity. We reanalyze measurements the tropospheric humidity variation [5] and describe observational strategies for improved diagnostics of the tropospheric humidity on Titan . Acknowledgements: Funding for this work is provided by the NSF grant AST-1008788 and NASA OPR grant NNX12AM81G. References: [1] Brown, et al. (2009) ApJ, 706, L110-L113. [2] Ádámkovics et al. (2010) Icarus, 208, 868-877. [3] Griffith et al. (2012) Icarus, 218, 975-988. [4] Rothman et al. (2013) AIP Conf. Proc., 1545, 223-231. [5] Penteado & Griffith (2010) Icarus, 206, 345-351.

Adamkovics, M.; Hayes, A.; Mitchell, J.; De Pater, I.; Young, E.

2013-12-01

67

Cloud Model-Based Spatial Data Mining  

Microsoft Academic Search

In spatial data mining, we have to deal with uncertainties in data and mining process. The nature of the uncertainties can be, for example, fuzziness and randomness. This paper proposed a cloud model-based data mining method that may simultaneously deal with randomness and fuzziness. First, cloud model is presented, which is described by using three numerical characteristics. Ex, En and

Shuliang Wang; Deren Li; Wenzhong Shi; Deyi Li; Xinzhou Wang

2003-01-01

68

Interactive Physically-Based Cloud Simulation  

Microsoft Academic Search

Articial clouds play an important role in the computer generation of natural outdoor scenes. Realistic modeling and rendering of such scenes is important for applications in games, military training simulations, ight simulations, and even in the creation of digital artistic media. We pro- pose a model for simulating cloud formation based on an efcient computational uid solver. We combine the

Derek Overby; Zeki Melek; John Keyser

2002-01-01

69

Total body height estimation using sacrum height in Anatolian Caucasians: multidetector computed tomography-based virtual anthropometry  

Microsoft Academic Search

Objective  Estimation of total body height is a major step when a subject has to be identified from his\\/her skeletal structures. In the\\u000a presence of decomposed skeletons and missing bones, estimation is usually based on regression equation for intact long bones.\\u000a If these bones are fragmented or missing, alternative structures must be used. In this study, the value of sacrum height

Hakki Muammer Karakas; Osman Celbis; Ahmet Harma; Banu Alicioglu

2011-01-01

70

TOWARDS A CLOUD CEILOMETER NETWORK REPORTING MIXING LAYER HEIGHT Wiel M.F. Wauben  

E-print Network

generally monitors and adjusts the power output of the laser and the sensitivity of the receiver is not designed to measure absolute aerosol concentrations, the aerosol signal can be observed in the backscatter performs basically a point measurement so that the spatial representativity of cloud information derived

Wauben, Wiel

71

Raman LIDAR Detection of Cloud Base  

NASA Technical Reports Server (NTRS)

Advantages introduced by Raman lidar systems for cloud base determination during precipitating periods are explored using two case studies of light rain and virga conditions. A combination of the Raman lidar derived profiles of water vapor mixing ratio and aerosol scattering ratio, together with the Raman scattered signals from liquid drops, can minimize or even eliminate some of the problems associated with cloud boundary detection using elastic backscatter lidars.

Demoz, Belay; Starr, David; Whiteman, David; Evans, Keith; Hlavka, Dennis; Peravali, Ravindra

1999-01-01

72

FILTERING OF AIRBORNE LASER SCANNER DATA BASED ON SEGMENTED POINT CLOUDS  

E-print Network

The extraction of points on the bare Earth from point clouds acquired by airborne laser scanning is the most time consuming and expensive part in the production of digital elevation models with laser scanning. Current algorithms for filtering point clouds assume the Earth’s surface to be continuous in all directions. This assumption leads to smoothed terrain representations in case of height discontinuities as they are often found in urban environments. This paper presents a new approach to filtering point clouds in which the point cloud is segmented into smooth segments that may still contain height discontinuities. The resulting segments are subsequently classified bare earth or object surfaces based on the geometric relationships with the surrounding segments. The paper demonstrates the advantages of segment-based classification with an analysis of data sets used in the ISPRS filter test. 1.

George Sithole A; George Vosselman B

73

INTERACTIVE PHYSICALLY-BASED CLOUD SIMULATION DEREK ROBERT OVERBY  

E-print Network

of Department) May 2002 Major Subject: Computer Science #12;ABSTRACT Interactive Physically-Based Cloud atmosphere. We propose a model for simulating cloud formation based on a basic computational fluid solver..................................................................... 3 2.1 Cloud Models in Computer Graphics............................. 3 2.2 Cloud Models

Keyser, John

74

Clouds  

NSDL National Science Digital Library

In this scenario-based, problem-based learning (PBL) activity, students investigate cloud formation, cloud classification, and the role of clouds in heating and cooling the Earth; how to interpret TRMM (Tropical Rainfall Measuring Mission) images and data; and the role clouds play in the Earth’s radiant budget and climate. Students assume the role of weather interns in a state climatology office and assist a frustrated student in a homework assignment. Learning is supported by a cloud in a bottle and an ice-albedo demonstration, a three-day cloud monitoring outdoor activity, and student journal assignments. The hands-on activities require two 2-liter soda bottles, an infrared heat lamp, and two thermometers. The resource includes a teacher's guide, questions and answer key, assessment rubric, glossary, and an appendix with information supporting PBL in the classroom.

75

Macrophysical and optical properties of midlatitude high-altitude clouds from 4 ground-based lidars and collocated CALIOP observations  

NASA Astrophysics Data System (ADS)

Cirrus clouds not only play a major role in the energy budget of the Earth-Atmosphere system, but are also important in the hydrological cycle [Stephens et al., 1990; Webster, 1994]. According to satellite passive remote sensing, high-altitude clouds cover as much as 40% of the earth's surface on average (Liou 1986; Stubenrauch et al., 2006) and can reach 70% of cloud cover over the Tropics (Wang et al., 1996; Nazaryan et al., 2008). Hence, given their very large cloud cover, they have a major role in the climate system (Lynch et al. 2001). Cirrus clouds can be classified into three distinct families according to their optical thickness, namely subvisible clouds (OD<0.03), semi-transparent clouds (0.03clouds (0.3clouds represent 50% or more of cirrus cloud population. The radiative effects of cirrus clouds are found to be significant by many studies both at the top of the atmosphere and surface. The contribution of the subvisible and semi-transparent classes is strongly affected by levels of other scatterers in the atmosphere (gases, aerosols). This makes them quite an important topic of study at the global scale. In the present work, we applied the cloud structure analysis algorithm STRAT to long time series of lidar backscatter profiles from multiple locations around the world. Our goal was to establish a Mid-Latitude climatology of cirrus clouds macrophysical properties based on active remote sensing: ground-based lidars at four mid-latitude observatories and the spaceborne instrument CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization). Lidar sampling, macrophysical (cloud base height, cloud top height, cloud thickness) and optical (cloud optical thickness) properties statistics are then evaluated and compared between the four observatories ground-based lidar measurements and quasi-simultaneously CALIOP overpasses. We note an overall good consistency in the macrophysical properties statistics derived from ground- based Lidar and CALIOP. For high altitude clouds, using consistent transmission-based retrieval methods, discrepancies are found in COT retrievals between ground Lidars and CALIOP. Ground-based Lidar retrievals contain less thick cirrus clouds than CALIOP. Overall, the results show that cirrus clouds with COD<0.1 (not included in historical cloud climatologies) represent 30-50% of the non-opaque cirrus class (COD<3, Pressure<440mb from ISCCP). Finally, we analyze the statistic consistencies between each dataset and investigate the possible bias due to lidar sampling and instrument/algorithm differences between ground-based lidar and CALIOP.

Dupont, J. C.; Haeffelin, M.; Morille, Y.; Noel, V.; Keckhut, P.; Comstock, J.; Winker, D.; Chervet, P.; Roblin, A.

2009-04-01

76

Implementation of GIS Spatial Data Mining Based on Cloud Theory  

Microsoft Academic Search

The transforms between qualitative concepts and their quantitative expressions plan an important role in spatial data mining & knowledge discovery (SDMKD), the cloud theory is this kind of powerful tools. Based on the cloud model, this paper presents a expression method for uncertain direction by using two-dimensional normal cloud, builds a data mining pattern through combining cloud theory and rough

Wang Xiao hui; Xie Jiancang; Li Jianxun; Luo Jungang; Liu Fuchao

2006-01-01

77

A Coalitional Game-Based Mechanism for Forming Cloud Federations  

E-print Network

A Coalitional Game-Based Mechanism for Forming Cloud Federations Lena Mashayekhy Department--We model the cloud federation formation problem using concepts from coalitional game theory by considering game where cloud providers decide to form a coalition (cloud federation) to allocate VMs dynamically

Grosu, Daniel

78

Adjusting thresholds of satellite-based convective initiation interest fields based on the cloud environment  

NASA Astrophysics Data System (ADS)

The Time-Space Exchangeability (TSE) concept states that similar characteristics of a given property are closely related statistically for objects or features within close proximity. In this exercise, the objects considered are growing cumulus clouds, and the data sets to be considered in a statistical sense are geostationary satellite infrared (IR) fields that help describe cloud growth rates, cloud top heights, and whether cloud tops contain significant amounts of frozen hydrometeors. In this exercise, the TSE concept is applied to alter otherwise static thresholds of IR fields of interest used within a satellite-based convective initiation (CI) nowcasting algorithm. The convective environment in which the clouds develop dictate growth rate and precipitation processes, and cumuli growing within similar mesoscale environments should have similar growth characteristics. Using environmental information provided by regional statistics of the interest fields, the thresholds are examined for adjustment toward improving the accuracy of 0-1 h CI nowcasts. Growing cumulus clouds are observed within a CI algorithm through IR fields for many 1000 s of cumulus cloud objects, from which statistics are generated on mesoscales. Initial results show a reduction in the number of false alarms of ~50%, yet at the cost of eliminating approximately ~20% of the correct CI forecasts. For comparison, static thresholds (i.e., with the same threshold values applied across the entire satellite domain) within the CI algorithm often produce a relatively high probability of detection, with false alarms being a significant problem. In addition to increased algorithm performance, a benefit of using a method like TSE is that a variety of unknown variables that influence cumulus cloud growth can be accounted for without need for explicit near-cloud observations that can be difficult to obtain.

Jewett, Christopher P.; Mecikalski, John R.

2013-11-01

79

Designing SCIT Architecture Pattern in a Cloud-based Environment  

E-print Network

C-SCIT (Cloud- based Self-Cleansing Intrusion Tolerant) scheme that can provide enhanced intrusion. The main contribution of this paper is to design a Cloud- based Self-Cleansing Intrusion Tolerance (C

Sood, Arun K.

80

Global extreme wave height variability based on satellite data  

NASA Astrophysics Data System (ADS)

The spatial and temporal variability of the extreme significant wave height (SWH) in the ocean is presented. The study has been performed using a highly reliable dataset from several satellite altimeter missions, which provide a good worldwide coverage for the period 1992 onwards. A non-stationary extreme value analysis, which models seasonality and interannual variations, has been applied to characterize the extreme SWH. The interannual variability is explained through variations in the atmosphere and ocean systems, represented by different climate indices, allowing a quantitative contribution of the climate-related patterns. Results demonstrate the strong relationship between the interannual variability of extreme SWH and different ocean and atmosphere variations. A contribution of the AO and NAO indices in the North Atlantic ocean (e.g., every positive unit of the AO explains up to 70 cm of extreme wave height south of Iceland), the NINO3 in the Pacific (every negative unit of NINO3 explains up to 60 cm of extreme wave height in the Drake Passage), the SAM in the Southern ocean and the DMI in the Indian ocean reveal these climate patterns as the most relevant in the interannual extreme wave climate.

Izaguirre, Cristina; Méndez, Fernando J.; Menéndez, Melisa; Losada, Inigo J.

2011-05-01

81

Matching clouds and shadows based on high-resolution satellite image  

NASA Astrophysics Data System (ADS)

Clouds are the obstruction of visual and infrared remote sensing and their shadows may also lead up to an intolerable bias of the true reflectance of the underlying terrain elements. Thus a reliable cloud and shadow mask is essential before the further processing. Clouds cast shadows on the earth's surface. On the high resolution remote sensing images, clouds' profiles and their shadows' are resemblant. Based on this truth, we employed a robust image matching algorithm called Modified Partial Hausforff Distance(MPHD) to find the match with every cloud and its shadow and finally calculated the pixel distance between them. Before the match task we took into account topologic relationships such as coverage and fragmentation to improve the match result. Not only were the match pairs detected but also the pixel distances from each cloud to its shadow were obtained. Then we can use a pixel distance to predict a shadow of a cloud by translating the cloud. Given sunbeam's direction and viewing angles we may get cloud height with simple geometry calculation.

Chen, Xiaodong; Chen, Jianyu; Pan, Delu; Mao, Zhihua; Huang, Haiqing

2006-12-01

82

Renmin Universtiy of China Cloud-based Data Management  

E-print Network

TB PB ppt #12;1 /29 Jiaheng Lu Renmin Universtiy of China Cloud-based Data Management: Challenges of China Cloud data management XML data management Research experience and interesting #12;3 /29 Outline

83

Microwave propagation characteristics depending on base-station antenna height in an urban area  

Microsoft Academic Search

We have conducted propagation experiments assuming the environment of low base station antenna height and, hence, microcells in an urban area and have reported their results. In this report, we report the results of a propagation experiment in the microwave band that is conducted with transmission base station antennas installed at height sufficiently higher or lower than the surrounding building

K. Sakawa; H. Masui; M. Ishii; H. Shimizu; T. Kobayashi

2001-01-01

84

Statistical analysis of an LES shallow cumulus cloud ensemble using a cloud tracking algorithm  

NASA Astrophysics Data System (ADS)

A technique for the tracking of individual clouds in a Large Eddy Simulation (LES) is presented. We use this technique on an LES of a shallow cumulus cloud field based upon the Barbados Oceanographic and Meteorological Experiment (BOMEX) to calculate statistics of cloud height, lifetime, and other physical properties for individual clouds in the model. We also examine the question of nature versus nurture in shallow cumulus clouds: do properties at cloud base determine the upper-level properties of the clouds (nature), or are cloud properties determined by the environmental conditions they encounter (nurture). We find that clouds which ascend through an environment that has been pre-moistened by previous cloud activity are no more likely to reach the inversion than clouds that ascend through a drier environment. Cloud base thermodynamic properties are uncorrelated with upper-level cloud properties, while mean fractional entrainment and detrainment rates display moderate correlations with cloud properties up to the inversion. Conversely, cloud base area correlates well with upper-level cloud area and maximum cloud height. We conclude that cloud thermodynamic properties are primarily influenced by entrainment and detrainment processes, cloud area and height are primarily influenced by cloud base area, and thus nature and nurture both play roles in the dynamics of BOMEX shallow cumulus clouds.

Dawe, J. T.; Austin, P. H.

2012-01-01

85

Statistical analysis of a LES shallow cumulus cloud ensemble using a cloud tracking algorithm  

NASA Astrophysics Data System (ADS)

A technique for the tracking of individual clouds in a Large Eddy Simulation (LES) is presented. We use this technique on a LES of a shallow cumulus cloud field based upon the Barbados Oceanographic and Meteorological Experiment (BOMEX) to calculate statistics of cloud height, lifetime, and other physical properties for individual clouds in the model. We also examine the question of nature versus nurture in shallow cumulus clouds: do properties at cloud base determine the upper-level properties of the clouds (nature), or are cloud properties determined by the environmental conditions they encounter (nurture). We find that clouds which ascend through an environment that has been pre-moistened by previous cloud activity are no more likely to reach the inversion than clouds that ascend through a drier environment. Cloud base thermodynamic properties are uncorrelated with upper-level cloud properties, while mean fractional entrainment and detrainment rate displays moderate correlations with cloud properties up to the inversion. Conversely, cloud base area correlates well with upper-level cloud area and maximum cloud height. We conclude that cloud thermodynamic properties are primarily influenced by entrainment and detrainment processes, cloud area and height are primarily influenced by cloud base area, and thus nature and nurture both play roles in the dynamics of BOMEX shallow cumulus clouds.

Dawe, J. T.; Austin, P. H.

2011-08-01

86

Cloud field classification based on textural features  

NASA Technical Reports Server (NTRS)

An essential component in global climate research is accurate cloud cover and type determination. Of the two approaches to texture-based classification (statistical and textural), only the former is effective in the classification of natural scenes such as land, ocean, and atmosphere. In the statistical approach that was adopted, parameters characterizing the stochastic properties of the spatial distribution of grey levels in an image are estimated and then used as features for cloud classification. Two types of textural measures were used. One is based on the distribution of the grey level difference vector (GLDV), and the other on a set of textural features derived from the MaxMin cooccurrence matrix (MMCM). The GLDV method looks at the difference D of grey levels at pixels separated by a horizontal distance d and computes several statistics based on this distribution. These are then used as features in subsequent classification. The MaxMin tectural features on the other hand are based on the MMCM, a matrix whose (I,J)th entry give the relative frequency of occurrences of the grey level pair (I,J) that are consecutive and thresholded local extremes separated by a given pixel distance d. Textural measures are then computed based on this matrix in much the same manner as is done in texture computation using the grey level cooccurrence matrix. The database consists of 37 cloud field scenes from LANDSAT imagery using a near IR visible channel. The classification algorithm used is the well known Stepwise Discriminant Analysis. The overall accuracy was estimated by the percentage or correct classifications in each case. It turns out that both types of classifiers, at their best combination of features, and at any given spatial resolution give approximately the same classification accuracy. A neural network based classifier with a feed forward architecture and a back propagation training algorithm is used to increase the classification accuracy, using these two classes of features. Preliminary results based on the GLDV textural features alone look promising.

Sengupta, Sailes Kumar

1989-01-01

87

Building vulnerability assessment based on cloud model  

NASA Astrophysics Data System (ADS)

This study aims at building a general framework for estimating building vulnerability to blast-fragmentation warhead of a missile. Considering the fuzziness and randomness existing in the damage criterion rules, cloud models are applied to represent the qualitative concepts. On the basis of building geometric description, element criticality analysis, blast wave and fragment movement description, and meeting analysis of fragments and target, kill probabilities of the components are estimated by the shot line method. The damage state of the whole building given the threat is obtained by cloud model based uncertainty reasoning and the proposed similarity measure, enabling both randomness of probability reasoning and the fuzziness of the traditional fuzzy logic to be considered. Experimental results demonstrate that the proposed method can provide useful reference for optimizing warhead design and mission efficiency evaluation.

Sun, Xixia; Cai, Chao

2013-10-01

88

Retrievals of cloud fraction and cloud albedo from surface-based shortwave radiation measurements: A comparison of 16 year measurements  

NASA Astrophysics Data System (ADS)

radiation measurements have been widely conducted to gain information on clouds and the surface radiation budget. To examine the existing techniques of cloud property retrieval and explore the underlying reasons for uncertainties, a newly developed approach that allows for simultaneous retrievals of cloud fraction and cloud albedo from ground-based shortwave broadband radiation measurements, XL2013, is used to derive cloud fraction and cloud albedo from ground-based shortwave broadband radiation measurements at the Department of Energy Atmospheric Radiation Measurement Southern Great Plains site. The new results are compared with the separate retrieval of cloud fraction and cloud albedo using Long2006 and Liu2011, respectively. The retrievals from the broadband radiation measurements are further compared with those based on shortwave spectral measurements (Min2008). The comparison shows overall good agreement between the retrievals of both cloud fraction and cloud albedo, with noted differences, however. The Long2006 and Min2008 cloud fractions are greater on average than the XL2013 values. Compared to Min2008 and Liu2011, the XL2013 cloud albedo tends to be greater for thin clouds but smaller for thick clouds, with the differences decreasing with increasing cloud fraction; the neglect of land surface albedo and cloud absorption by Liu2011 also contributes the difference in cloud albedo. Further analysis reveals that the approaches that retrieve cloud fraction and cloud albedo separately may suffer from mutual contamination of errors in retrieved cloud fraction and cloud albedo.

Xie, Yu; Liu, Yangang; Long, Charles N.; Min, Qilong

2014-07-01

89

Macrophysical and optical properties of midlatitude cirrus clouds from four ground-based lidars and collocated CALIOP observations  

SciTech Connect

Ground-based lidar and CALIOP datasets gathered over four mid-latitude sites, two US and two French sites, are used to evaluate the consistency of cloud macrophysical and optical property climatologies that can be derived by such datasets. The consistency in average cloud height (both base and top height) between the CALIOP and ground datasets ranges from -0.4km to +0.5km. The cloud geometrical thickness distributions vary significantly between the different datasets, due in part to the original vertical resolutions of the lidar profiles. Average cloud geometrical thicknesses vary from 1.2 to 1.9km, i.e. by more than 50%. Cloud optical thickness distributions in subvisible, semi-transparent and moderate intervals differ by more than 50% between ground and space-based datasets. The cirrus clouds with 2 optical thickness below 0.1 (not included in historical cloud climatologies) represent 30-50% of the non-opaque cirrus class. The differences in average cloud base altitude between ground and CALIOP datasets of 0.0-0.1 km, 0.0-0.2 km and 0.0-0.2 km can be attributed to irregular sampling of seasonal variations in the ground-based data, to day-night differences in detection capabilities by CALIOP, and to the restriction to situations without low-level clouds in ground-based data, respectively. The cloud geometrical thicknesses are not affected by irregular sampling of seasonal variations in the ground-based data, while up to 0.0-0.2 km and 0.1-0.3 km differences can be attributed to day-night differences in detection capabilities by CALIOP, and to the restriction to situations without lowlevel clouds in ground-based data, respectively.

Dupont, Jean-Charles; Haeffelin, M.; Morille, Y.; Noel, V.; Keckhut, P.; Winker, D.; Comstock, Jennifer M.; Chervet, P.; Roblin, A.

2010-05-27

90

Assessment of MISR and MODIS cloud top heights through inter-comparison with a back-scattering lidar at SIRTA  

E-print Network

, France Received 3 November 2003; revised 10 December 2003; accepted 30 January 2004; published 27, and tend to detect a low water cloud rather than an overlying thin ice cloud in multi-layer cloud as with the highest quality MISR wind retrieval correction (BestWind) [C. Moroney, 2003, private communication]. MODIS

91

Pervasive Forensic Analysis Based on Mobile Cloud Computing  

Microsoft Academic Search

Cloud computing has become one of mobile's hottest topics. Moving computing processing and data storage away from mobile devices and into large data centers, mobile applications enable the users to improve productivity, to share data and to collaborate with others. Considering the benefits of mobile cloud computing, the forensic service based on mobile cloud computing could be good solution to

Jooyoung Lee; Dowon Hong

2011-01-01

92

PoU based sharp features extraction from point cloud  

Microsoft Academic Search

Sharp features of 3D point clouds play an important role in many geometric computations and modeling application. In this paper, a novel modified Partition of Unity (PoU) Based Sharp feature extraction algorithm is proposed, which is directly operated on discrete point clouds. For every point in target point cloud, spherical neighborhood with radius ? is acquired with the help of

Cao Juming; W. Slam; Liang Jin; Liang Xinhe; Zhang Dehai; Liu Jianwei; Yao Xinhui

2010-01-01

93

Research on electronic data security strategy based on cloud computing  

Microsoft Academic Search

Cloud computing is a new network computing paradigm based on IP architecture, it is everywhere, pick up any tech magazine or visit almost any IT website or blog and you'll be sure to see talk about cloud computing. Cloud computing applications without borders, mobility and other characteristics has led to their own safety and security issues in the security field.

Guoman Lin

2012-01-01

94

Simulation of Cumuliform Clouds Based on Computational Fluid Dynamics  

Microsoft Academic Search

Simulation of natural phenomena is one of the important research fields in computer graphics. In particular, clouds play an important role in creating images of outdoor scenes. Fluid simulation is effective in creating realistic clouds because clouds are the visualization of atmospheric fluid. In this paper, we propose a simulation technique, based on a numerical solution of the partial differential

R. Miyazaki; Y. Dobashi; T. Nishita

2002-01-01

95

Process-based Management of Cloud Computing Infrastructure  

E-print Network

Process-based Management of Cloud Computing Infrastructure Background Cloud Computing with minimal management effort. Examples of modern cloud computing solutions include (but are not limited to is an emerging computing capability that provides an abstraction between the computing resource and its

Krause, Rolf

96

Optimization-Based Virtual Machine Manager for Private Cloud Computing  

Microsoft Academic Search

In this paper, an optimal resource management framework for cloud computing environment is presented. Based on virtualization technology, the workload to be processed on a virtual machine can be moved (i.e., outsourced) from private cloud (i.e., in-house computer system) to the service provider in public cloud. The framework introduces the virtual machine manager (VMM) in private cloud operating to minimize

Dusit Niyato

2011-01-01

97

Collaboration-Based Cloud Computing Security Management Framework  

Microsoft Academic Search

Although the cloud computing model is considered to be a very promising internet-based computing platform, it results in a loss of security control over the cloud-hosted assets. This is due to the outsourcing of enterprise IT assets hosted on third-party cloud computing platforms. Moreover, the lack of security constraints in the Service Level Agreements between the cloud providers and consumers

Mohemed Almorsy; John Grundy; Amani S. Ibrahim

2011-01-01

98

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

NASA Astrophysics Data System (ADS)

Using 2B-CLDCLASS-LIDAR (radar-lidar) cloud classification and 2B-FLXHR-LIDAR radiation products from CloudSat over 4 years, this study evaluates the co-occurrence frequencies of different cloud types, analyzes their along-track horizontal scales and cloud radiative effects (CREs), and utilizes the vertical distributions of cloud types to evaluate cloud-overlap assumptions. The statistical results show that high clouds, altostratus (As), altocumulus (Ac) and cumulus (Cu) tend to coexist with other cloud types. However, stratus (St) (or stratocumulus, Sc), nimbostratus (Ns) and convective clouds are much more likely to exhibit individual features than other cloud types. On average, altostratus-over-stratus/stratocumulus cloud systems have a maximum horizontal scale of 17.4 km, with a standard deviation of 23.5 km. Altocumulus-over-cumulus cloud types have a minimum scale of 2.8 km, with a standard deviation of 3.1 km. By considering the weight of each multilayered cloud type, we find that the global mean instantaneous net CREs of multilayered cloud systems during the daytime are approximately -41.3 and -50.2 W m-2, which account for 40.1 and 42.3% of the global mean total net CREs at the top of the atmosphere (TOA) and at the surface, respectively. The radiative contributions of high-over-altocumulus and high-over-stratus/stratocumulus (or cumulus) in the all multilayered cloud systems are dominant due to their frequency. Considering the overlap of cloud types, the cloud fraction based on the random overlap assumption is underestimated over vast oceans, except in the west-central Pacific Ocean warm pool. Obvious overestimations mainly occur over tropical and subtropical land masses. In view of a lower degree of overlap than that predicted by the random overlap assumption to occur over the vast ocean, particularly poleward of 40° S, the study therefore suggests that a linear combination of minimum and random overlap assumptions may further improve the predictions of 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.

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

2015-01-01

99

Design of intelligent height control system based on eddy current sensor  

Microsoft Academic Search

In water jet cutting process, cutting quality and speed depend on the distance between cutting head and object. To solve the problem that it is difficult to realize precise control of water jet cutting technique in height track system, this paper designs a waterproofing eddy height-adjusting system based on eddy sensor in view of metal plate. This system realizes non-contact

Haiying Wang; Xuefei Wang; Zhenhe Sun; Yanjun Chen

2010-01-01

100

Is School-Based Height and Weight Screening of Elementary Students Private and Reliable?  

ERIC Educational Resources Information Center

The Institute of Medicine recommends school-based body mass index (BMI) screening as an obesity prevention strategy. While school nurses have provided height/weight screening for years, little has been published describing measurement reliability or process. This study evaluated the reliability of height/weight measures collected by school nurses…

Stoddard, Sarah A.; Kubik, Martha Y.; Skay, Carol

2008-01-01

101

Urban air pollution modelling and measurements of boundary layer height  

Microsoft Academic Search

An urban field trial has been undertaken with the aim of assessing the performance of the boundary layer height (BLH) determination of two models: the Met Office Unified Model (UM) and a Gaussian-type plume model, ADMS. Pulsed Doppler lidar data were used to measure mixing layer height and cloud base heights for a variety of meteorological conditions over a 3

F. Davies; D. R. Middleton; K. E. Bozier

2007-01-01

102

Temporal and spatial variations of global deep cloud systems based on CloudSat and CALIPSO satellite observations  

NASA Astrophysics Data System (ADS)

The spatial and temporal global distribution of deep clouds was analyzed using a four-year dataset (2007-10) based on observations from CloudSat and CALIPSO. Results showed that in the Northern Hemisphere, the number of deep cloud systems (DCS) reached a maximum in summer and a minimum in winter. Seasonal variations in the number of DCS varied zonally in the Southern Hemisphere. DCS occurred most frequently over central Africa, the northern parts of South America and Australia, and Tibet. The mean cloud-top height of deep cloud cores (TDCC) decreased toward high latitudes in all seasons. DCS with the highest TDCC and deepest cores occurred over east and south Asian monsoon regions, west-central Africa and northern South America. The width of DCS (WDCS) increased toward high latitudes in all seasons. In general, DCS were more developed in the horizontal than in the vertical direction over high latitudes and vice versa over lower latitudes. Findings from this study show that different mechanisms are behind the development of DCS at different latitudes. Most DCS at low latitudes are deep convective clouds which are highly developed in the vertical direction but cover a relatively small area in the horizontal direction; these DCS have the highest TDCC and smallest WDCS. The DCS at midlatitudes are more likely to be caused by cyclones, so they have less vertical development than DCS at low latitudes. DCS at high latitudes are mainly generated by large frontal systems, so they have the largest WDCS and the smallest TDCC.

Peng, Jie; Zhang, Hua; Li, Zhanqing

2014-05-01

103

Cloudy Sounding and Cloud-Top Height Retrieval From AIRS Alone Single Field-of-View Radiance Measurements  

NASA Technical Reports Server (NTRS)

High-spectral resolution measurements from the Atmospheric Infrared Sounder (AIRS) onboard the EOS (Earth Observing System) Aqua satellite provide unique information about atmospheric state, surface and cloud properties. This paper presents an AIRS alone single field-of-view (SFOV) retrieval algorithm to simultaneously retrieve temperature, humidity and ozone profiles under all weather conditions, as well as cloud top pressure (CTP) and cloud optical thickness (COT) under cloudy skies. For optically thick cloud conditions the above-cloud soundings are derived, whereas for clear skies and optically thin cloud conditions the profiles are retrieved from 0.005 hPa down to the earth's surface. Initial validation has been conducted by using the operational MODIS (Moderate Resolution Imaging Spectroradiometer) product, ECMWF (European Center of Medium range Weather Forecasts) analysis fields and radiosonde observations (RAOBs). These inter-comparisons clearly demonstrate the potential of this algorithm to process data from 38 high-spectral infrared (IR) sounder instruments.

Weisz, Elisabeth; Li, Jun; Li, Jinlong; Zhou, Daniel K.; Huang, Hung-Lung; Goldberg, Mitchell D.; Yang, Ping

2007-01-01

104

A new approach to retrieving cirrus cloud height with a combination of MODIS 1.24-and  

E-print Network

.24- and 1.38-mm) with similar cloud scattering and absorp- tion properties but very different water vapor absorption properties. This channel combination is used to accurately infer the column water vapor amount Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) measurements. By investigating the spatial

Baum, Bryan A.

105

A 25-month database of stratus cloud properties generated from ground-based measurements at the Atmospheric Radiation Measurement Southern Great Plains Site  

Microsoft Academic Search

A 25-month database of the macrophysical, microphysical, and radiative properties of isolated and overcast low-level stratus clouds has been generated using a newly developed parameterization and surface measurements from the Atmospheric Radiation Measurement central facility in Oklahoma. The database (5-min resolution) includes two parts: measurements and retrievals. The former consist of cloud base and top heights, layer-mean temperature, cloud liquid

Xiquan Dong; Patrick Minnis; Thomas P. Ackerman; Eugene E. Clothiaux; Gerald G. Mace; Charles N. Long; James C. Liljegren

2000-01-01

106

Fate of Acids in Clouds 1. Combination with bases dissolved in clouds: acids neutralized  

E-print Network

problems. E#11;ects of Acid Rain 1. Vegetation: SO 2 is toxic to plants #15; Leaves damaged below pH 3 rain { Athens and Rome cathedrals and statues: pollution leads to acid rain #15; SteelFate of Acids in Clouds 1. Combination with bases dissolved in clouds: acids neutralized NH 3 (g

Schofield, Jeremy

107

Efficient modeling of height datum based on GIS  

NASA Astrophysics Data System (ADS)

Since the proposal of Digital Earth, its research and applications are continuing to be deepened, and now Smart City is more indepth implementation of the Digital Earth. The unification of global or regional vertical datums has always been one of the main geodesy studies to achieve Smart City, as Smart City must first realize the seamless integration of multi-source geo-dataset. This paper introduces spatio-temporal data management and interactive visualization into the entire process of vertical datum modelling. We demonstrate that the efficiency of modelling is greatly improved. In this paper GIS database is used to manage all dataset such as tidal station data, gravity field model data, GPS leveling data, and vertical datum data for evaluation and analysis. We use geographic information visualization technique to graphically display the results, together with the interactive browsing, to convert tedious digital information to easy-to-understand images. Consequently, researchers can quickly and comprehensively grasp the macro and micro information. Finally, an efficient and interactive prototype operating platforms for vertical datum modeling is constructed based on GIS.

Qiao, Q.

2014-04-01

108

Height compensation using ground inclination estimation in inertial sensor-based pedestrian navigation.  

PubMed

In an inertial sensor-based pedestrian navigation system, the position is estimated by double integrating external acceleration. A new algorithm is proposed to reduce z axis position (height) error. When a foot is on the ground, a foot angle is estimated using accelerometer output. Using a foot angle, the inclination angle of a road is estimated. Using this road inclination angle, height difference of one walking step is estimated and this estimation is used to reduce height error. Through walking experiments on roads with different inclination angles, the usefulness of the proposed algorithm is verified. PMID:22164061

Park, Sang Kyeong; Suh, Young Soo

2011-01-01

109

A depolarisation lidar-based method for the determination of liquid-cloud microphysical properties  

NASA Astrophysics Data System (ADS)

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

Donovan, D. P.; Klein Baltink, H.; Henzing, J. S.; de Roode, S. R.; Siebesma, A. P.

2015-01-01

110

Cloud Base Cloud Condensation Nuclei Measurements in Summertime North Dakota Airborne measurements of cloud condensation nuclei (CCN) were made just below  

E-print Network

Cloud Base Cloud Condensation Nuclei Measurements in Summertime North Dakota ` Objective Airborne measurements of cloud condensation nuclei (CCN) were made just below developing cumulus clouds in North Dakota and analyze the three summers of measurements. Acknowledgments The North Dakota (ND) Atmospheric Resource

Delene, David J.

111

Cloud Based Processing of Large Photometric Surveys  

NASA Astrophysics Data System (ADS)

Astronomy, as is the case with many scientific domains, has entered the realm of being a data rich science. Nowhere is this reflected more clearly than in the growth of large area surveys, such as the recently completed Sloan Digital Sky Survey (SDSS) or the Dark Energy Survey, which will soon obtain PB of imaging data. The data processing on these large surveys is a major challenge. In this paper, we demonstrate a new approach to this common problem. We propose the use of cloud-based technologies (e.g., Hadoop MapReduce) to run a data analysis program (e.g., SExtractor) across a cluster. Using the intermediate key/value pair design of Hadoop, our framework matches objects across different SExtractor invocations to create a unified catalog from all SDSS processed data. We conclude by presenting our experimental results on a 432 core cluster and discuss the lessons we have learned in completing this challenge.

Farivar, R.; Brunner, R. J.; Santucci, R.; Campbell, R.

2013-10-01

112

A 25-month database of stratus cloud properties generated from ground-based measurements at the Atmospheric Radiation Measurement Southern Great Plains Site  

SciTech Connect

A 25-month database of the macrophysical, microphysical, and radiative properties of isolated and overcast low-level stratus clouds has been generated using a newly developed parameterization and surface measurements from the Atmospheric Radiation Measurement central facility in Oklahoma. The database (5-min resolution) includes two parts: measurements and retrievals. The former consist of cloud base and top heights, layer-mean temperature, cloud liquid water path, and solar transmission ratio measured by a ground-based lidar/ceilometer and radar pair, radiosondes, a microwave radiometer, and a standard Eppley precision spectral pyranometer, respectively. The retrievals include the cloud-droplet effective radius and number concentration and broadband shortwave optical depth and cloud and top-of-atmosphere albedos. Stratus without any overlying mid or high-level clouds occurred most frequently during winter and least often during summer. Mean cloud-layer altitudes and geometric thicknesses were higher and greater, respectively, in summer than in winter. Both quantities are positively correlated with the cloud-layer mean temperature. Mean cloud-droplet effective radii range from 8.1 {mu}m in winter to 9.7 {mu}m during summer, while cloud-droplet number concentrations during winter are nearly twice those in summer. Since cloud liquid water paths are almost the same in both seasons, cloud optical depth is higher during the winter, leading to greater cloud albedos and lower cloud transmittances. (c) 2000 American Geophysical Union.

Dong, Xiquan [Meteorology Department, University of Utah, Salt Lake City (United States)] [Meteorology Department, University of Utah, Salt Lake City (United States); Minnis, Patrick [NASA Langley Research Center, Hampton, Virginia (United States)] [NASA Langley Research Center, Hampton, Virginia (United States); Ackerman, Thomas P. [Pacific Northwest National Laboratory, DOE, Richland, Washington (United States)] [Pacific Northwest National Laboratory, DOE, Richland, Washington (United States); Clothiaux, Eugene E. [Department of Meteorology, Pennsylvania State University, University Park (United States)] [Department of Meteorology, Pennsylvania State University, University Park (United States); Mace, Gerald G. [Meteorology Department, University of Utah, Salt Lake City (United States)] [Meteorology Department, University of Utah, Salt Lake City (United States); Long, Charles N. [Department of Meteorology, Pennsylvania State University, University Park (United States)] [Department of Meteorology, Pennsylvania State University, University Park (United States); Liljegren, James C. [Ames Laboratory, DOE, Ames, Iowa (United States)] [Ames Laboratory, DOE, Ames, Iowa (United States)

2000-02-27

113

Measurement of Dense-Phase Bed Height in CFB Boiler Based on Flame Image Processing Technique  

Microsoft Academic Search

This paper proposes a method to measure the dense-phase bed height by edge-detection of Charge Coupled Device based on flame image processing technique in Circulated Fluidized Bed (CFB) boiler. The detection system was installed in a 480t\\/h CFB boiler, image processing model has been built,and in-situ experiment was carried out. Real-time bed height is reliable and meets the bed pressure

Zi-xue Luo; Dun-dun Wang; Duan Lian; Huai-chun Zhou

2009-01-01

114

Web based RFID Asset Management Solution established on Cloud Services  

E-print Network

Web based RFID Asset Management Solution established on Cloud Services Arunabh Chattopadhyay, California 90095 Abstract--In this paper, an RFID architecture has been pre- sented where the traditional role of the localised middleware has been distributed to the RFID reader and a cloud based web service

California at Los Angeles, University of

115

Identity-Based Authentication for Cloud Computing  

Microsoft Academic Search

Cloud computing is a recently developed new technology for complex systems with massive-scale services sharing among numerous\\u000a users. Therefore, authentication of both users and services is a significant issue for the trust and security of the cloud\\u000a computing. SSL Authentication Protocol (SAP), once applied in cloud computing, will become so complicated that users will\\u000a undergo a heavily loaded point both

Hongwei Li; Yuanshun Dai; Ling Tian; Haomiao Yang

2009-01-01

116

Research on Cloud Computing-Based Online Payment Mode  

Microsoft Academic Search

Cloud computing brings a significant revolution to e-business. Software, platform and infrastructure appear on the Internet in succession that extend electronic business chain and form the latest mode named whole e-business. This thesis puts forward cloud computing-based online payment mode after lucubrating theories of cloud computing and limitations of existing online payment models. The organizational structure, technical architecture and business

Zhiran Wang

2011-01-01

117

S'COOL Lesson: Estimating Altitude of Water Cloud Base  

NSDL National Science Digital Library

Students begin by determining dew point using an aluminum can, stirring rod, ice and thermometer. Air temperature is also measured and recorded. Students then use those two data in conjunction with the Lifting Condensation Level approximation, to estimate the base altitude of visible (low level) clouds. The Students' Cloud Observations On-Line (S'COOL) project engages students in making and reporting ground truth observations of clouds then comparing those observations with data from the CERES satellite instrument.

118

Enhancing dynamic cloud-based services using network virtualization  

Microsoft Academic Search

It is envisaged that services and applications will migrate to a cloud-computing paradigm where thin-clients on user-devices access, over the network, applications hosted in data centers by application service providers. Examples are cloud-based gaming applications and cloud-supported virtual desktops. For good performance and efficiency, it is critical that these services are delivered from locations that are the best for the

Fang Hao; T. V. Lakshman; Sarit Mukherjee; Haoyu Song

2010-01-01

119

Enhancing dynamic cloud-based services using network virtualization  

Microsoft Academic Search

It is envisaged that services and applications will migrate to a cloud-computing paradigm where thin-clients on user- devices access, over the network, applications hosted in data centers by application service providers. Examples are cloud- based gaming applications and cloud-supported virtual desk- tops. For good performance and efficiency, it is critical that these services are delivered from locations that are the

Fang Hao; T. V. Lakshman; Sarit Mukherjee; Haoyu Song

2009-01-01

120

Clouds  

NSDL National Science Digital Library

Clouds comprise a wonderful focus for classroom study. They're ubiquitous, ever-changing, scientifically interesting and, most importantly for teachers, they're cheap. The material presented here includes sections on cloud formation, cloud types, cloud pictures, other cloud-related phenomena, and a glossary.

Wozniak, Carl

121

Cloud Base Signature in Transmission Spectra of Exoplanet Atmospheres  

E-print Network

We present an analytical model for the transmission spectrum of a transiting exoplanet, showing that a cloud base can produce an observable inflection point in the spectrum. The wavelength and magnitude of the inflection can be used to break the degeneracy between the atmospheric pressure and the abundance of the main cloud material, however, the abundance still depends on cloud particle size. An observed inflection also provides a specific point on the atmospheric P-T profile, giving us a "thermometer" to directly validate or rule out postulated cloud species. We apply the model to the transit spectrum of HD 189733b.

Vahidinia, Sanaz; Marley, Mark; Fortney, Jonathan

2014-01-01

122

A depolarisation lidar based method for the determination of liquid-cloud microphysical properties  

NASA Astrophysics Data System (ADS)

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

Donovan, D. P.; Klein Baltink, H.; Henzing, J. S.; de Roode, S. R.; Siebesma, A. P.

2014-09-01

123

Distributed Search Engine for an IaaS Based Cloud  

Microsoft Academic Search

Cloud based online storage enables the storage of massive data. In these systems, a full text search engine is very important for finding documents. In this paper, we propose a distributed search engine suitable for searching a cloud. In our previous work, we developed a distributed search engine, the cooperative search engine (CSE). We now extend the CSE to search

Yuuta Ichikawa; Minoru Uehara

2011-01-01

124

Interactive Physically-Based Cloud Simulation Derek Overby  

E-print Network

Interactive Physically-Based Cloud Simulation Derek Overby dereko@cs.tamu.edu Zeki Melek melekzek@neo.tamu.edu Texas A&M University College Station, TX John Keyser keyser@cs.tamu.edu Abstract Artificial clouds play an important role in the computer generation of natural outdoor scenes. Realistic modeling and rendering

Keyser, John

125

Logistics information management system based on Google cloud computing platform  

Microsoft Academic Search

Cloud computing can appeal for applications with a high degree of computational complexity and dynamics. And it can help users decrease their investments for their own IT infrastructure. So it is good for small and medium enterprises. In this paper, we propose to design and implement a logistics information management system based on Google cloud computing platform. It runs with

Jiahai Liu; Gao Yang; Haihua Wu; Linwei Zheng

2012-01-01

126

Comparing the cloud vertical structure derived from several methods based on measured atmospheric profiles and active surface measurements  

NASA Astrophysics Data System (ADS)

The cloud vertical distribution and especially the cloud base height, which is linked to cloud type, is an important characteristic in order to describe the impact of clouds in a changing climate. In this work several methods to estimate the cloud vertical structure (CVS) based on atmospheric sounding profiles are compared, considering number and position of cloud layers, with a ground based system which is taken as a reference: the Active Remote Sensing of Clouds (ARSCL). All methods establish some conditions on the relative humidity, and differ on the use of other variables, the thresholds applied, or the vertical resolution of the profile. In this study these methods are applied to 125 radiosonde profiles acquired at the ARM Southern Great Plains site during all seasons of year 2009 and endorsed by GOES images, to confirm that the cloudiness conditions are homogeneous enough across their trajectory. The overall agreement for the methods ranges between 44-88%; four methods produce total agreements around 85%. Further tests and improvements are applied on one of these methods. In addition, we attempt to make this method suitable for low resolution vertical profiles, which could be useful in atmospheric modeling. The total agreement, even when using low resolution profiles, can be improved up to 91% if the thresholds for a moist layer to become a cloud layer are modified to minimize false negatives with the current data set, thus improving overall agreement.

Costa-Surós, M.; Calbó, J.; González, J. A.; Long, C. N.

2013-06-01

127

Decadal changes in thin cirrus height measured by MISR  

NASA Astrophysics Data System (ADS)

Thin cirrus clouds are difficult to detect and the operational cloud-height product from the Multiangle Imaging Spectro Radiometer (MISR) may miss thin cirrus when it overlies thicker, lower-level cloud. To detect thin cirrus over clear skies with MISR, cloud-heights above 10 km were retrieved using a stereo matching technique on the oblique camera pairs and re-projected onto the nadir camera after correction for parallax and winds. A merged dataset, including measurements from the CERES broadband radiometer, was used to compare measured outgoing longwave radiation (OLR) to the OLR from a column model of longwave radiative transfer that uses MISR cloud-top heights and reanalysis data as input parameters. After accounting for uncertainties in modeled OLR of ± 4 W m-2 due to uncertainties in the input properties, especially for known high cloud, surface temperature and specific humidity, the average difference of 17 W m-2 cannot be directly explained, and is accounted for by the addition of thin cirrus with a coverage of 60%. The analysis of tropical MISR orbits with standard processing shows a decline in cloud-top height since 2000. After validation of oblique-detected thin cirrus with ground-based sensors, the additional cirrus detected over the tropics also showed a decline in cirrus-top height. The decadal changes and climatological comparisons in cloud-top height of thin cirrus in the tropics are also reported.

Prasad, Abhnil Amtesh; Davies, Roger

2013-05-01

128

Lidar based vegetation height models to quantify carbon stocks in Galveston saltmarshes  

NASA Astrophysics Data System (ADS)

Concern over global climate change has stimulated much interest in identifying existing and potential carbon sinks. Wetland ecosystems are highly recognized for their high productivity and thus as major terrestrial carbon (C) sinks. The rapid decline in the extent and health of these wetland ecosystems has created a need for non-destructive methods for the study of their C dynamics. However, these biomass estimates are mostly based on vegetation structural properties, particularly based on vegetation height models. Hence, for better quantification of vegetation biomass and C estimates, the accuracy of vegetation height models derived using lidar data is of paramount importance. Yet, unlike in woody vegetation dominated ecosystems, the use of lidar in saltmarshes is limited due to several reasons: 1) relatively dense vegetation cover limits laser penetration affecting the accuracy of terrain and thus vegetation height estimates; and 2) relatively shorter vegetation demands high point density data with high vertical accuracy to capture relatively smaller differences between terrain and vegetation canopy surfaces. Thus, the use of lidar data to characterize saltmarsh vegetation community demands appropriate methodologies. Our overall objective in this study was to develop a methodology for deriving salt marsh vegetation height models using airborne lidar data. More specific objectives involved: (1) understanding the interaction between discrete-return airborne lidar data and marsh vegetation; (2) finding appropriate grid sizes for deriving terrain and vegetation height models; and (3) analyze lidar-derived surface accuracies by comparing estimates to field measurements. In this study, we used 1m point spacing airborne lidar data from Federal Emergency Management Agency (FEMA) program to derive vegetation height models (VHM) for Spartina alterniflora saltmarshes in Galveston, Texas. We first derived digital terrain models (DEMs) and verified their vertical accuracy using field elevation data obtained using survey grade GPS. These DEMs served as input for deriving VHMs at different grid sizes (i.e. 1m, 3m, 5m and 10m). These VHMs were evaluated against field-collected vegetation height measurements collected using different approaches. Field measurements of vegetation heights include visual estimates for different grid sizes and also individual plant and culm heights. With this work, we seek to develop a remote sensing (RS) based approach to predict vegetation biomass (and thus C) in these salt marsh ecosystems using lidar data available for much of the coastal United States. Our study brings a contribution to the methods of estimating biomass and thus C estimates based on light detection and ranging (lidar) data as a nondestructive method.

Kulawardhana, R. W.; Popescu, S. C.; Feagin, R. A.

2012-12-01

129

Community-based complex cloud data center  

NASA Astrophysics Data System (ADS)

The communication infrastructure is a critical component of a large-scale cloud data center. It needs to provide the best performance available while keeping overprovisioning and, lately even more important, power consumption, to the minimum. Aiming to provide a unified solution that will have high performance together with economical benefits and power consumption reduction, in this paper, we propose a new community-based scale-free model for data center network architecture. By comparing the proposed model to other similar solutions we show that the performance of the network in terms of average path length, bandwidth and resilience is similar to the state-of-the-art models. In our presented detailed analysis of the model properties, our focus is set on exploring how heterogeneity in terms of different type of network equipment influences the basic network properties. We also present solutions and network metrics that can be used in conjunction to the introduced community structure in order to additionally increase the performance.

Filiposka, Sonja; Juiz, Carlos

2015-02-01

130

Interactive physically-based cloud simulation  

E-print Network

computational fluid solver. This allows us to simulate the complex air motion that contributes to cloud formation in our atmosphere. Among the natural processes that we simulate are buoyancy, relative humidity, and condensation. Because we have built...

Overby, Derek Robert

2002-01-01

131

Reconciling Ground-Based and Space-Based Estimates of the Frequency of Occurrence and Radiative Effect of Clouds around Darwin, Australia  

SciTech Connect

The objective of this paper is to investigate whether estimates of the cloud frequency of occurrence and associated cloud radiative forcing as derived from ground-based and satellite active remote sensing and radiative transfer calculations can be reconciled over a well instrumented active remote sensing site located in Darwin, Australia, despite the very different viewing geometry and instrument characteristics. It is found that the ground-based radar-lidar combination at Darwin does not detect most of the cirrus clouds above 10 km (due to limited lidar detection capability and signal obscuration by low-level clouds) and that the CloudSat radar - Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) combination underreports the hydrometeor frequency of occurrence below 2 km height, due to instrument limitations at these heights. The radiative impact associated with these differences in cloud frequency of occurrence is large on the surface downwelling shortwave fluxes (ground and satellite) and the top-of atmosphere upwelling shortwave and longwave fluxes (ground). Good agreement is found for other radiative fluxes. Large differences in radiative heating rate as derived from ground and satellite radar-lidar instruments and RT calculations are also found above 10 km (up to 0.35 Kday-1 for the shortwave and 0.8 Kday-1 for the longwave). Given that the ground-based and satellite estimates of cloud frequency of occurrence and radiative impact cannot be fully reconciled over Darwin, caution should be exercised when evaluating the representation of clouds and cloud-radiation interactions in large-scale models and limitations of each set of instrumentation should be considered when interpreting model-observations differences.

Protat, Alain; Young, Stuart; McFarlane, Sally A.; L'Ecuyer, Tristan; Mace, Gerald G.; Comstock, Jennifer M.; Long, Charles N.; Berry, Elizabeth; Delanoe, Julien

2014-02-01

132

A LIDAR-based crop height measurement system for Miscanthus giganteus Lei Zhang, Tony E. Grift  

E-print Network

A LIDAR-based crop height measurement system for Miscanthus giganteus Lei Zhang, Tony E. Grift for Miscanthus giganteus (MxG), to be used as a component in a future Look Ahead Yield Monitor (LAYM of the crops that holds considerable promise owing to its high yield and low input requirements, is Miscanthus

133

Optimization of the geopotential heights information used in a rainfall based weather patterns classification over Austria.  

E-print Network

-up classification, COST733, geopotential height field, optimization, comparison, daily precipitation shape fields in France, is applied for the definition of a WP classification useful for the description of Austrian heavy-up approach": the "bottom" part consists of the definition of a given number of classes based on daily

Paris-Sud XI, Université de

134

Cloud radiative forcing on surface shortwave fluxes: A case study based on Cloud Lidar and Radar Exploratory Test  

SciTech Connect

Shortwave downward fluxes for selected stratus, cirrus, and mixed phase cloud cases are analyzed based on cloud and surface radiation measurements from the Cloud Lidar and Radar Exploratory Test conducted in the Denver-Boulder area of Colorado during September-October, 1989. A medium resolution, discrete-ordinate shortwave radiative transfer model is used to provide clear-sky conditions and to examine the cloud shortwave radiative forcing. The model simulation indicates that for stratus clouds the effective radius increases with increasing liquid water path. For cirrus cloud simulation, the model results are within 10% agreement with the surface flux measurements. However, using the one-dimensional plane-parallel model, the model results are in poor agreement for the inhomogeneous mixed phase cloud case. Over the elevated observation site, the reduction in shortwave downward flux by clouds can be as large as 40% for a small cloud water path value of 20 g m{sup {minus}2}. The variation in observed cloud shortwave forcing is highly correlated with the integrated cloud water path. The normalized (by the clear-sky value) cloud shortwave forcing increases rapidly when the cloud water path is small. The rate of increase decreases, and the normalized cloud forcing approaches saturation when cloud water path becomes large. The magnitude of the saturation value depends on cloud optical properties. The variation in observed cloud forcing is consistent with the theoretical curve for cloudy atmospheric albedo variation. At a constant value of cloud water path, the normalized cloud forcing increases with solar zenith angle. The solar zenith angle effect is less significant for larger value of cloud water path. 44 refs., 11 figs.

Shi, L. [Univ. of California, San Diego, CA (United States)] [Univ. of California, San Diego, CA (United States)

1994-12-20

135

Stellar Encounters with the Oort Cloud Based on Hipparcos Data  

NASA Technical Reports Server (NTRS)

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.

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

1998-01-01

136

Uav-Based Photogrammetric Point Clouds - Tree STEM Mapping in Open Stands in Comparison to Terrestrial Laser Scanner Point Clouds  

NASA Astrophysics Data System (ADS)

In both ecology and forestry, there is a high demand for structural information of forest stands. Forest structures, due to their heterogeneity and density, are often difficult to assess. Hence, a variety of technologies are being applied to account for this "difficult to come by" information. Common techniques are aerial images or ground- and airborne-Lidar. In the present study we evaluate the potential use of unmanned aerial vehicles (UAVs) as a platform for tree stem detection in open stands. A flight campaign over a test site near Freiburg, Germany covering a target area of 120 × 75 [m2] was conducted. The dominant tree species of the site is oak (quercus robur) with almost no understory growth. Over 1000 images with a tilt angle of 45° were shot. The flight pattern applied consisted of two antipodal staggered flight routes at a height of 55 [m] above the ground. We used a Panasonic G3 consumer camera equipped with a 14-42 [mm] standard lens and a 16.6 megapixel sensor. The data collection took place in leaf-off state in April 2013. The area was prepared with artificial ground control points for transformation of the structure-from-motion (SFM) point cloud into real world coordinates. After processing, the results were compared with a terrestrial laser scanner (TLS) point cloud of the same area. In the 0.9 [ha] test area, 102 individual trees above 7 [cm] diameter at breast height were located on in the TLS-cloud. We chose the software CMVS/PMVS-2 since its algorithms are developed with focus on dense reconstruction. The processing chain for the UAV-acquired images consists of six steps: a. cleaning the data: removing of blurry, under- or over exposed and off-site images; b. applying the SIFT operator [Lowe, 2004]; c. image matching; d. bundle adjustment; e. clustering; and f. dense reconstruction. In total, 73 stems were considered as reconstructed and located within one meter of the reference trees. In general stems were far less accurate and complete as in the TLS-point cloud. Only few stems were considered to be fully reconstructed. From the comparison of reconstruction achievement with respect to height above ground, we can state that reconstruction accuracy decreased in the crown layer of the stand. In addition we were cutting 50 [cm] slices in z-direction and applied a robust cylinder fit to the stem slices. Radii of the TLS-cloud and the SFM-cloud surprisingly correlated well with a Pearson's correlation coefficient of r = 0.696. This first study showed promising results for UAV-based forest structure modelling. Yet, there is a demand for additional research with regard to vegetation stages, flight pattern, processing setup and the utilisation of spectral information.

Fritz, A.; Kattenborn, T.; Koch, B.

2013-08-01

137

Plume height, volume, and classification of explosive volcanic eruptions based on the Weibull function  

NASA Astrophysics Data System (ADS)

The Weibull distribution between volume and square root of isopach area has been recently introduced for determining volume of tephra deposits, which is crucial to the assessment of the magnitude and hazards of explosive volcanoes. We show how the decay of the size of the largest lithics with the square root of isopleth area can also be well described using a Weibull function and how plume height correlates strongly with corresponding Weibull parameters. Variations of median grain size (Md ?) values with square root of area of the associated contours can be, similarly, well fitted with a Weibull function. Weibull parameters, derived for both the thinning of tephra deposits and the decrease of grain size (both maximum lithic diameter and Md ?), with a proxy for the distance from vent (e.g., square root of isoline areas) can be combined to classify the style of explosive volcanic eruptions. Accounting for the uncertainty in the derivation of eruptive parameters (e.g., plume height and volume of tephra deposits) is crucial to any classification of eruptive style and hazard assessment. Considering a typical uncertainty of 20 % for the determination of plume height, a new eruption classification scheme based on selected Weibull parameters is proposed. Ultraplinian, Plinian, Subplinian, and small-moderate explosive eruptions are defined on the ground of plume height and mass eruption rate. Overall, the Weibull fitting represents a versatile and reliable strategy for the estimation of both the volume of tephra deposits and the height of volcanic plumes and for the classification of eruptive style. Nonetheless, due to the typically large uncertainties (mainly due to availability of data, compilation of isopach and isopleth maps, and discrepancies from empirical best fits), plume height, volume, and magnitude of explosive eruptions cannot be considered as absolute values, regardless of the technique used. It is important that various empirical and analytical methods are applied in order to assess such an uncertainty.

Bonadonna, Costanza; Costa, Antonio

2013-08-01

138

CloudSeal: End-to-End Content Protection in Cloud-based Storage and Delivery Services  

E-print Network

Introduction Security issues have been one of the top concerns for cloud computing [1], despite the increase words: Cloud computing, content delivery network, proxy-based re-encryption, secret sharing. 1 in the public cloud remains a challenging task. The issue becomes more difficult with flexible content

Ryder, Barbara G.

139

Cloud Computing Based E-Learning System  

ERIC Educational Resources Information Center

Cloud computing technologies although in their early stages, have managed to change the way applications are going to be developed and accessed. These technologies are aimed at running applications as services over the internet on a flexible infrastructure. Microsoft office applications, such as word processing, excel spreadsheet, access database…

Al-Zoube, Mohammed; El-Seoud, Samir Abou; Wyne, Mudasser F.

2010-01-01

140

A High Resolution Hydrometer Phase Classifier Based on Analysis of Cloud Radar Doppler Spectra  

Microsoft Academic Search

The lifecycle and radiative properties of clouds are highly sensitive to the phase of their hydrometeors (i.e., liquid or ice). Knowledge of cloud phase is essential for specifying the optical properties of clouds, or else, large errors can be introduced in the calculation of the cloud radiative fluxes. Current parameterizations of cloud water partition in liquid and ice based on

Edward Luke; Pavlos Kollias

2007-01-01

141

FAME-C: cloud property retrieval using synergistic AATSR and MERIS observations  

NASA Astrophysics Data System (ADS)

A newly developed daytime cloud property retrieval algorithm, FAME-C (Freie Universität Berlin AATSR MERIS Cloud), is presented. Synergistic observations from the Advanced Along-Track Scanning Radiometer (AATSR) and the Medium Resolution Imaging Spectrometer (MERIS), both mounted on the polar-orbiting Environmental Satellite (Envisat), are used for cloud screening. For cloudy pixels two main steps are carried out in a sequential form. First, a cloud optical and microphysical property retrieval is performed using an AATSR near-infrared and visible channel. Cloud phase, cloud optical thickness, and effective radius are retrieved, and subsequently cloud water path is computed. Second, two cloud top height products are retrieved based on independent techniques. For cloud top temperature, measurements in the AATSR infrared channels are used, while for cloud top pressure, measurements in the MERIS oxygen-A absorption channel are used. Results from the cloud optical and microphysical property retrieval serve as input for the two cloud top height retrievals. Introduced here are the AATSR and MERIS forward models and auxiliary data needed in FAME-C. Also, the optimal estimation method, which provides uncertainty estimates of the retrieved property on a pixel basis, is presented. Within the frame of the European Space Agency (ESA) Climate Change Initiative (CCI) project, the first global cloud property retrievals have been conducted for the years 2007-2009. For this time period, verification efforts are presented, comparing, for four selected regions around the globe, FAME-C cloud optical and microphysical properties to cloud optical and microphysical properties derived from measurements of the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra satellite. The results show a reasonable agreement between the cloud optical and microphysical property retrievals. Biases are generally smallest for marine stratocumulus clouds: -0.28, 0.41 ?m and -0.18 g m-2 for cloud optical thickness, effective radius and cloud water path, respectively. This is also true for the root-mean-square deviation. Furthermore, both cloud top height products are compared to cloud top heights derived from ground-based cloud radars located at several Atmospheric Radiation Measurement (ARM) sites. FAME-C mostly shows an underestimation of cloud top heights when compared to radar observations. The lowest bias of -0.3 km is found for AATSR cloud top heights for single-layer clouds, while the highest bias of -3.0 km is found for AATSR cloud top heights for multilayer clouds. Variability is low for MERIS cloud top heights for low-level clouds, and high for MERIS cloud top heights for mid-level and high-level single-layer clouds, as well as for both AATSR and MERIS cloud top heights for multilayer clouds.

Carbajal Henken, C. K.; Lindstrot, R.; Preusker, R.; Fischer, J.

2014-11-01

142

Evaluation of ground-based remotely sensed liquid water cloud properties using shortwave radiation measurements  

E-print Network

Evaluation of ground-based remotely sensed liquid water cloud properties using shortwave radiation 2009 Accepted 31 January 2010 Water cloud optical and microphysical properties are required 1. Introduction The microphysical and optical properties of liquid water clouds are important

Haak, Hein

143

Agent-Based Service Composition in Cloud Computing  

NASA Astrophysics Data System (ADS)

In a Cloud-computing environment, consumers, brokers, and service providers interact to achieve their individual purposes. In this regard, service providers offer a pool of resources wrapped as web services, which should be composed by broker agents to provide a single virtualized service to Cloud consumers. In this study, an agent-based test bed for simulating Cloud-computing environments is developed. Each Cloud participant is represented by an agent, whose behavior is defined by means of colored Petri nets. The relationship between web services and service providers is modeled using object Petri nets. Both Petri net formalisms are combined to support a design methodology for defining concurrent and parallel service choreographies. This results in the creation of a dynamic agent-based service composition algorithm. The simulation results indicate that service composition is achieved with a linear time complexity despite dealing with interleaving choreographies and synchronization of heterogeneous services.

Gutierrez-Garcia, J. Octavio; Sim, Kwang-Mong

144

A Hybrid GWR-Based Height Estimation Method for Building Detection in Urban Environments  

NASA Astrophysics Data System (ADS)

LiDAR has become important data sources in urban modelling. Traditional methods of LiDAR data processing for building detection require high spatial resolution data and sophisticated methods. The aerial photos, on the other hand, provide continuous spectral information of buildings. But the segmentation of the aerial photos cannot distinguish between the road surfaces and the building roof. This paper develops a geographically weighted regression (GWR)-based method to identify buildings. The method integrates characteristics derived from the sparse LiDAR data and from aerial photos. In the GWR model, LiDAR data provide the height information of spatial objects which is the dependent variable, while the brightness values from multiple bands of the aerial photo serve as the independent variables. The proposed method can thus estimate the height at each pixel from values of its surrounding pixels with consideration of the distances between the pixels and similarities between their brightness values. Clusters of contiguous pixels with higher estimated height values distinguish themselves from surrounding roads or other surfaces. A case study is conducted to evaluate the performance of the proposed method. It is found that the accuracy of the proposed hybrid method is better than those by image classification of aerial photos along or by height extraction of LiDAR data alone. We argue that this simple and effective method can be very useful for automatic detection of buildings in urban areas.

Wei, X.; Yao, X.

2014-11-01

145

A vegetation height classification approach based on texture analysis of a single VHR image  

NASA Astrophysics Data System (ADS)

Vegetation height is a crucial feature in various applications related to ecological mapping, enhancing the discrimination among different land cover or habitat categories and facilitating a series of environmental tasks, ranging from biodiversity monitoring and assessment to landscape characterization, disaster management and conservation planning. Primary sources of information on vegetation height include in situ measurements and data from active satellite or airborne sensors, which, however, may often be non-affordable or unavailable for certain regions. Alternative approaches on extracting height information from very high resolution (VHR) satellite imagery based on texture analysis, have recently been presented, with promising results. Following the notion that multispectral image bands may often be highly correlated, data transformation and dimensionality reduction techniques are expected to reduce redundant information, and thus, the computational cost of the approaches, without significantly compromising their accuracy. In this paper, dimensionality reduction is performed on a VHR image and textural characteristics are calculated on its reconstructed approximations, to show that their discriminatory capabilities are maintained up to a large degree. Texture analysis is also performed on the projected data to investigate whether the different height categories can be distinguished in a similar way.

Petrou, Z. I.; Manakos, I.; Stathaki, T.; Tarantino, C.; Adamo, M.; Blonda, P.

2014-03-01

146

Towards Constraint-based High Performance Cloud System in the Process of Cloud Computing Adoption in an Organization  

E-print Network

Cloud computing is penetrating into various domains and environments, from theoretical computer science to economy, from marketing hype to educational curriculum and from R&D lab to enterprise IT infrastructure. Yet, the currently developing state of cloud computing leaves several issues to address and also affects cloud computing adoption by organizations. In this paper, we explain how the transition into the cloud can occur in an organization and describe the mechanism for transforming legacy infrastructure into a virtual infrastructure-based cloud. We describe the state of the art of infrastructural cloud, which is essential in the decision making on cloud adoption, and highlight the challenges that can limit the scale and speed of the adoption. We then suggest a strategic framework for designing a high performance cloud system. This framework is applicable when transformation cloudbased deployment model collides with some constraints. We give an example of the implementation of the framework in a desi...

Simalango, Mikael Fernandus; Oh, Sangyoon

2010-01-01

147

Barrier height enhancement of Ni/GaN Schottky diode using Ru based passivation scheme  

SciTech Connect

Wet chemical passivation of n-GaN surface using Ru based solution has been reported. X-ray photoelectron spectroscopy characterization of the GaN surface revealed removal of surface oxides by the introduction of Ru complex species. Ni/n-GaN Schottky barrier diodes were fabricated on passivated GaN and a remarkable improvement in Schottky barrier height from 0.76?eV to 0.92?eV was observed.

Kumar, Ashish, E-mail: dr.akmr@gmail.com; Kumar, Mukesh; Singh, R. [Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016 (India); Kaur, Riajeet [Department of Physics, National Institute of Technology, Kurukshetra 136119 (India); Joshi, Amish G. [CSIR - National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi - 110 012 (India); Vinayak, Seema [Solid State Physical Laboratory, Timarpur, Delhi 110054 (India)

2014-03-31

148

Volcanic plume height measured by seismic waves based on a mechanical model  

USGS Publications Warehouse

In August 2008 an unmonitored, largely unstudied Aleutian volcano, Kasatochi, erupted catastrophically. Here we use seismic data to infer the height of large eruptive columns such as those of Kasatochi based on a combination of existing fluid and solid mechanical models. In so doing, we propose a connection between a common, observable, short-period seismic wave amplitude to the physics of an eruptive column. To construct a combined model, we estimate the mass ejection rate of material from the vent on the basis of the plume height, assuming that the height is controlled by thermal buoyancy for a continuous plume. Using the estimated mass ejection rate, we then derive the equivalent vertical force on the Earth through a momentum balance. Finally, we calculate the far-field surface waves resulting from the vertical force. The model performs well for recent eruptions of Kasatochi and Augustine volcanoes if v, the velocity of material exiting the vent, is 120-230 m s-1. The consistency between the seismically inferred and measured plume heights indicates that in these cases the far-field ~1 s seismic energy radiated by fluctuating flow in the volcanic jet during the eruption is a useful indicator of overall mass ejection rates. Thus, use of the model holds promise for characterizing eruptions and evaluating ash hazards to aircraft in real time on the basis of far-field short-period seismic data. This study emphasizes the need for better measurements of eruptive plume heights and a more detailed understanding of the full spectrum of seismic energy radiated coeruptively.

Prejean, Stephanie G.; Brodsky, Emily E.

2011-01-01

149

Cloud-based space situational awareness: initial design and evaluation  

NASA Astrophysics Data System (ADS)

The need for a global collaborating space situational awareness (SSA) network, including radars, optical and other sensors for communication and surveillance, has become a top priority for most countries who own or operate man-made space-crafts. Such a SSA system requires vast storage, powerful computing capacity and the ability to serve hundreds of thousands of users to access the same database. These requirements make traditional distributed networking system insufficient. Cloud computing, which features scalable and elastic storage and computing services, has been recognized as an ideal candidate that can meet the challenges of SSA systems' requirements. In this paper, we propose a Cloud-based information fusion system for SSA and examine a prototype that serves space tracking algorithms. We discuss the benefits of using Cloud Computing as an alternative for data processing and storage and explore details of Cloud implementation for a representative SSA system environment.

Liu, Bingwei; Chen, Yu; Shen, Dan; Chen, Genshe; Pham, Khanh; Blasch, Erik

2013-05-01

150

A cloud-based simulation architecture for pandemic influenza simulation.  

PubMed

High-fidelity simulations of pandemic outbreaks are resource consuming. Cluster-based solutions have been suggested for executing such complex computations. We present a cloud-based simulation architecture that utilizes computing resources both locally available and dynamically rented online. The approach uses the Condor framework for job distribution and management of the Amazon Elastic Computing Cloud (EC2) as well as local resources. The architecture has a web-based user interface that allows users to monitor and control simulation execution. In a benchmark test, the best cost-adjusted performance was recorded for the EC2 H-CPU Medium instance, while a field trial showed that the job configuration had significant influence on the execution time and that the network capacity of the master node could become a bottleneck. We conclude that it is possible to develop a scalable simulation environment that uses cloud-based solutions, while providing an easy-to-use graphical user interface. PMID:22195089

Eriksson, Henrik; Raciti, Massimiliano; Basile, Maurizio; Cunsolo, Alessandro; Fröberg, Anders; Leifler, Ola; Ekberg, Joakim; Timpka, Toomas

2011-01-01

151

Global surface-based cloud observation for ISCCP  

NASA Technical Reports Server (NTRS)

Visual observations of cloud cover are hindered at night due to inadequate illumination of the clouds. This usually leads to an underestimation of the average cloud cover at night, especially for the amounts of middle and high clouds, in climatologies on surface observations. The diurnal cycles of cloud amounts, if based on all the surface observations, are therefore in error, but they can be obtained more accurately if the nighttime observations are screened to select those made under sufficient moonlight. Ten years of nighttime weather observations from the northern hemisphere in December were classified according to the illuminance of moonlight or twilight on the cloud tops, and a threshold level of illuminance was determined, above which the clouds are apparently detected adequately. This threshold corresponds to light from a full moon at an elevation angle of 6 degrees or from a partial moon at higher elevation, or twilight from the sun less than 9 degrees below the horizon. It permits the use of about 38% of the observations made with the sun below the horizon. The computed diurnal cycles of total cloud cover are altered considerably when this moonlight criterion is imposed. Maximum cloud cover over much of the ocean is now found to be at night or in the morning, whereas computations obtained without benefit of the moonlight criterion, as in our published atlases, showed the time of maximum to be noon or early afternoon in many regions. Cloud cover is greater at night than during the day over the open oceans far from the continents, particularly in summer. However, near noon maxima are still evident in the coastal regions, so that the global annual average oceanic cloud cover is still slightly greater during the day than at night, by 0.3%. Over land, where daytime maxima are still obtained but with reduced amplitude, average cloud cover is 3.3% greater during the daytime. The diurnal cycles of total cloud cover we obtain are compared with those of ISCCP for a few regions; they are generally in better agreement if the moonlight criterion is imposed on the surface observations. Using the moonlight criterion, we have analyzed ten years (1982-1991) of surface weather observations over land and ocean, worldwide, for total cloud cover and for the frequency of occurrence of clear sky, fog and precipitation The global average cloud cover (average of day and night) is about 2% higher if we impose the moonlight criterion than if we use all observations. The difference is greater in winter than in summer, because of the fewer hours of darkness in the summer. The amplitude of the annual cycle of total cloud cover over the Arctic Ocean and at the South Pole is diminished by a few percent when the moonlight criterion is imposed. The average cloud cover for 1982-1991 is found to be 55% for northern hemisphere land, 53% for southern hemisphere land, 66% for northern hemisphere ocean, and 70% for southern hemisphere ocean, giving a global average of 64%. The global average for daytime is 64.6% for nighttime 63.3%.

1994-01-01

152

Comparing the cloud vertical structure derived from several methods based on measured atmospheric profiles and active surface measurements  

NASA Astrophysics Data System (ADS)

The cloud vertical distribution and especially the cloud base height, which is linked to cloud type, is an important characteristic in order to describe the impact of clouds on climate. In this work several methods to estimate the cloud vertical structure (CVS) based on atmospheric sounding profiles are compared, considering number and position of cloud layers, with a ground based system which is taken as a reference: the Active Remote Sensing of Clouds (ARSCL). All methods establish some conditions on the relative humidity, and differ on the use of other variables, the thresholds applied, or the vertical resolution of the profile. In this study these methods are applied to 193 radiosonde profiles acquired at the ARM Southern Great Plains site during all seasons of year 2009 and endorsed by GOES images, to confirm that the cloudiness conditions are homogeneous enough across their trajectory. The perfect agreement (i.e. when the whole CVS is correctly estimated) for the methods ranges between 26-64%; the methods show additional approximate agreement (i.e. when at least one cloud layer is correctly assessed) from 15-41%. Further tests and improvements are applied on one of these methods. In addition, we attempt to make this method suitable for low resolution vertical profiles, like those from the outputs of reanalysis methods or from the WMO's Global Telecommunication System. The perfect agreement, even when using low resolution profiles, can be improved up to 67% (plus 25% of approximate agreement) if the thresholds for a moist layer to become a cloud layer are modified to minimize false negatives with the current data set, thus improving overall agreement.

Costa-Surós, M.; Calbó, J.; González, J. A.; Long, C. N.

2014-04-01

153

Evaluation of Cloud-Phase Retrieval Methods for SEVIRI on Meteosat-8 Using Ground-Based Lidar and Cloud Radar Data  

E-print Network

- erties such as cloud particle size, cloud temperature, cloud phase, water vapor and aerosol abundanceEvaluation of Cloud-Phase Retrieval Methods for SEVIRI on Meteosat-8 Using Ground-Based Lidar-phase retrievals obtained from cloud radar and lidar observations at Cabauw, Netherlands. Three aspects

Stoffelen, Ad

154

An Empirical Analysis of Scheduling Techniques for Real-time Cloud-based Data Processing  

E-print Network

An Empirical Analysis of Scheduling Techniques for Real-time Cloud-based Data Processing Linh T of current cloud infrastructures, to better support cloud-based data-intensive applications that are not only multiprocessor scheduling techniques for the cloud environment, we observe significant performance improve- ments

Loo, Boon Thau

155

Cloud-Based Collaborative Writing and the Common Core Standards  

ERIC Educational Resources Information Center

The Common Core State Standards emphasize the integration of technology skills into English Language Arts (ELA) instruction, recognizing the demand for technology-based literacy skills to be college- and career- ready. This study aims to examine how collaborative cloud-based writing is used in in a Colorado school district, where one-to-one…

Yim, Soobin; Warschauer, Mark; Zheng, Binbin; Lawrence, Joshua F.

2014-01-01

156

Designing a Secure Cloud-Based EHR System using Ciphertext-Policy Attribute-Based Encryption  

E-print Network

- ever, before cloud-based EHR systems can become a reality, issues of data security, patient privacyDesigning a Secure Cloud-Based EHR System using Ciphertext-Policy Attribute-Based Encryption Suhair@cs.rit.edu ABSTRACT As more and more healthcare organizations adopt electronic health records (EHRs), the case

Radziszowski, Stanislaw P.

157

Knowledge-Based Object Detection in Laser Scanning Point Clouds  

NASA Astrophysics Data System (ADS)

Object identification and object processing in 3D point clouds have always posed challenges in terms of effectiveness and efficiency. In practice, this process is highly dependent on human interpretation of the scene represented by the point cloud data, as well as the set of modeling tools available for use. Such modeling algorithms are data-driven and concentrate on specific features of the objects, being accessible to numerical models. We present an approach that brings the human expert knowledge about the scene, the objects inside, and their representation by the data and the behavior of algorithms to the machine. This "understanding" enables the machine to assist human interpretation of the scene inside the point cloud. Furthermore, it allows the machine to understand possibilities and limitations of algorithms and to take this into account within the processing chain. This not only assists the researchers in defining optimal processing steps, but also provides suggestions when certain changes or new details emerge from the point cloud. Our approach benefits from the advancement in knowledge technologies within the Semantic Web framework. This advancement has provided a strong base for applications based on knowledge management. In the article we will present and describe the knowledge technologies used for our approach such as Web Ontology Language (OWL), used for formulating the knowledge base and the Semantic Web Rule Language (SWRL) with 3D processing and topologic built-ins, aiming to combine geometrical analysis of 3D point clouds, and specialists' knowledge of the scene and algorithmic processing.

Boochs, F.; Karmacharya, A.; Marbs, A.

2012-07-01

158

Intuitive Terrain Reconstruction Using Height Observation-Based Ground Segmentation and 3D Object Boundary Estimation  

PubMed Central

Mobile robot operators must make rapid decisions based on information about the robot’s surrounding environment. This means that terrain modeling and photorealistic visualization are required for the remote operation of mobile robots. We have produced a voxel map and textured mesh from the 2D and 3D datasets collected by a robot’s array of sensors, but some upper parts of objects are beyond the sensors’ measurements and these parts are missing in the terrain reconstruction result. This result is an incomplete terrain model. To solve this problem, we present a new ground segmentation method to detect non-ground data in the reconstructed voxel map. Our method uses height histograms to estimate the ground height range, and a Gibbs-Markov random field model to refine the segmentation results. To reconstruct a complete terrain model of the 3D environment, we develop a 3D boundary estimation method for non-ground objects. We apply a boundary detection technique to the 2D image, before estimating and refining the actual height values of the non-ground vertices in the reconstructed textured mesh. Our proposed methods were tested in an outdoor environment in which trees and buildings were not completely sensed. Our results show that the time required for ground segmentation is faster than that for data sensing, which is necessary for a real-time approach. In addition, those parts of objects that were not sensed are accurately recovered to retrieve their real-world appearances. PMID:23235454

Song, Wei; Cho, Kyungeun; Um, Kyhyun; Won, Chee Sun; Sim, Sungdae

2012-01-01

159

Automatic Single Tree Detection in Plantations using UAV-based Photogrammetric Point clouds  

NASA Astrophysics Data System (ADS)

For reasons of documentation, management and certification there is a high interest in efficient inventories of palm plantations on the single plant level. Recent developments in unmanned aerial vehicle (UAV) technology facilitate spatial and temporal flexible acquisition of high resolution 3D data. Common single tree detection approaches are based on Very High Resolution (VHR) satellite or Airborne Laser Scanning (ALS) data. However, VHR data is often limited to clouds and does commonly not allow for height measurements. VHR and in particualar ALS data are characterized by high relatively high acquisition costs. Sperlich et al. (2013) already demonstrated the high potential of UAV-based photogrammetric point clouds for single tree detection using pouring algorithms. This approach was adjusted and improved for an application on palm plantation. The 9.4ha test site on Tarawa, Kiribati, comprised densely scattered growing palms, as well as abundant undergrowth and trees. Using a standard consumer grade camera mounted on an octocopter two flight campaigns at 70m and 100m altitude were performed to evaluate the effect Ground Sampling Distance (GSD) and image overlap. To avoid comission errors and improve the terrain interpolation the point clouds were classified based on the geometric characteristics of the classes, i.e. (1) palm, (2) other vegetation (3) and ground. The mapping accuracy amounts for 86.1 % for the entire study area and 98.2 % for dense growing palm stands. We conclude that this flexible and automatic approach has high capabilities for operational use.

Kattenborn, T.; Sperlich, M.; Bataua, K.; Koch, B.

2014-08-01

160

Comparison of cloud boundaries measured with 8.6 mm radar and 10.6 micrometer lidar  

NASA Technical Reports Server (NTRS)

One of the most basic cloud properties is location; the height of cloud base and the height of cloud top. The glossary of meteorology defines cloud base (top) as follows: 'For a given cloud or cloud layer, that lowest (highest) level in the atmosphere at which the air contains a perceptible quantity of cloud particles.' Our studies show that for a 8.66 mm radar, and a 10.6 micrometer lidar, the level at which cloud hydrometers become 'perceptible' can vary significantly as a function of the different wavelengths, powers, beamwidths and sampling rates of the two remote sensors.

Uttal, Taneil; Intrieri, Janet M.

1993-01-01

161

Portfolio Theory-Based Resource Assignment in a Cloud Computing System  

E-print Network

Portfolio Theory-Based Resource Assignment in a Cloud Computing System Inkwon Hwang and Massoud-- The focus of this paper is on energy-aware resource management in a cloud computing system. Much. Keywords- Cloud computing; portfolio effect; bin-packing; resource allocation I. INTRODUCTION Cloud

Pedram, Massoud

162

Re-Encryption-Based Key Management Towards Secure and Scalable Mobile Applications in Clouds  

E-print Network

of Waterloo Waterloo, Ontario, Canada ahasan@uwaterloo.ca Abstract--Cloud computing confers strong economic-encryption is applied to a cloud computing system in a unique way to address the demands of a mobile device environment. The proposed cloud-based re-encryption model is secure, efficient, and highly scalable in a cloud computing

163

Cloud-Based Technologies: Faculty Development, Support, and Implementation  

ERIC Educational Resources Information Center

The number of instructional offerings in higher education that are online, blended, or web-enhanced, including courses and programs, continues to grow exponentially. Alongside the growth of e-learning, higher education has witnessed the explosion of cloud-based or Web 2.0 technologies, a term that refers to the vast array of socially oriented,…

Diaz, Veronica

2011-01-01

164

Driver eye height measurement  

E-print Network

and Cumulative Distribution of Driver Eye Heights. 24 TABLE 5, ? Passenger Vehicles: Frequency of Driver Eye Heights. 25 TABLE 6. ? Passenger Vehicles: Cumulative Distributions of Driver Eye Heights 26 TABLE 7. ? Summary Results f rom Analysis of Variance... the driver eye height and the height of an assumed object are required in these computations. Format and style based cn the Transportation En ineering Journal of hg A + ' S ~fC~1 Guaranteeing drivers a safe stopping distance on horizontal curves requires...

Abrahamson, Anthony Daniel

1978-01-01

165

Cloud based emergency health care information service in India.  

PubMed

A hospital is a health care organization providing patient treatment by expert physicians, surgeons and equipments. A report from a health care accreditation group says that miscommunication between patients and health care providers is the reason for the gap in providing emergency medical care to people in need. In developing countries, illiteracy is the major key root for deaths resulting from uncertain diseases constituting a serious public health problem. Mentally affected, differently abled and unconscious patients can't communicate about their medical history to the medical practitioners. Also, Medical practitioners can't edit or view DICOM images instantly. Our aim is to provide palm vein pattern recognition based medical record retrieval system, using cloud computing for the above mentioned people. Distributed computing technology is coming in the new forms as Grid computing and Cloud computing. These new forms are assured to bring Information Technology (IT) as a service. In this paper, we have described how these new forms of distributed computing will be helpful for modern health care industries. Cloud Computing is germinating its benefit to industrial sectors especially in medical scenarios. In Cloud Computing, IT-related capabilities and resources are provided as services, via the distributed computing on-demand. This paper is concerned with sprouting software as a service (SaaS) by means of Cloud computing with an aim to bring emergency health care sector in an umbrella with physical secured patient records. In framing the emergency healthcare treatment, the crucial thing considered necessary to decide about patients is their previous health conduct records. Thus a ubiquitous access to appropriate records is essential. Palm vein pattern recognition promises a secured patient record access. Likewise our paper reveals an efficient means to view, edit or transfer the DICOM images instantly which was a challenging task for medical practitioners in the past years. We have developed two services for health care. 1. Cloud based Palm vein recognition system 2. Distributed Medical image processing tools for medical practitioners. PMID:22865161

Karthikeyan, N; Sukanesh, R

2012-12-01

166

Cloud Classification Based on Self-Organizing Feature Map and Probabilistic Neural Network  

Microsoft Academic Search

For overcoming the shortcoming of single ANN classifier being difficult used to identify and classify complex clouds, based on the multi-spectrum samples of stationary meteorology satellite cloud pictures, by computing and analysing the gray-grads and texture characters of satellite cloud picture samples, and picking-up some suitable cloud classification factors, a synthetic optimization SOM-PNN cloud classifier was designed and established. Firstly,

Ren Zhang; Yanlei Wang; Wei Liu; Weijun Zhu; Jiguang Wang

2006-01-01

167

Streaming Support for Data Intensive Cloud-Based Sequence Analysis  

PubMed Central

Cloud computing provides a promising solution to the genomics data deluge problem resulting from the advent of next-generation sequencing (NGS) technology. Based on the concepts of “resources-on-demand” and “pay-as-you-go”, scientists with no or limited infrastructure can have access to scalable and cost-effective computational resources. However, the large size of NGS data causes a significant data transfer latency from the client's site to the cloud, which presents a bottleneck for using cloud computing services. In this paper, we provide a streaming-based scheme to overcome this problem, where the NGS data is processed while being transferred to the cloud. Our scheme targets the wide class of NGS data analysis tasks, where the NGS sequences can be processed independently from one another. We also provide the elastream package that supports the use of this scheme with individual analysis programs or with workflow systems. Experiments presented in this paper show that our solution mitigates the effect of data transfer latency and saves both time and cost of computation. PMID:23710461

Issa, Shadi A.; Kienzler, Romeo; El-Kalioby, Mohamed; Tonellato, Peter J.; Wall, Dennis; Bruggmann, Rémy; Abouelhoda, Mohamed

2013-01-01

168

The Effects of Latency on Player Performance in Cloud-based Games  

E-print Network

The Effects of Latency on Player Performance in Cloud-based Games Mark Claypool and David Finkel, USA Email: {claypool,dfinkel}@cs.wpi.edu Abstract--Cloud-based games are an increasingly popular network aspects of cloud-based games and examining the effects of latency on traditional games, there has

Claypool, Mark

169

A cloud-based multimodality case file for mobile devices.  

PubMed

Recent improvements in Web and mobile technology, along with the widespread use of handheld devices in radiology education, provide unique opportunities for creating scalable, universally accessible, portable image-rich radiology case files. A cloud database and a Web-based application for radiologic images were developed to create a mobile case file with reasonable usability, download performance, and image quality for teaching purposes. A total of 75 radiology cases related to breast, thoracic, gastrointestinal, musculoskeletal, and neuroimaging subspecialties were included in the database. Breast imaging cases are the focus of this article, as they best demonstrate handheld display capabilities across a wide variety of modalities. This case subset also illustrates methods for adapting radiologic content to cloud platforms and mobile devices. Readers will gain practical knowledge about storage and retrieval of cloud-based imaging data, an awareness of techniques used to adapt scrollable and high-resolution imaging content for the Web, and an appreciation for optimizing images for handheld devices. The evaluation of this software demonstrates the feasibility of adapting images from most imaging modalities to mobile devices, even in cases of full-field digital mammograms, where high resolution is required to represent subtle pathologic features. The cloud platform allows cases to be added and modified in real time by using only a standard Web browser with no application-specific software. Challenges remain in developing efficient ways to generate, modify, and upload radiologic and supplementary teaching content to this cloud-based platform. Online supplemental material is available for this article. PMID:24819664

Balkman, Jason D; Loehfelm, Thomas W

2014-01-01

170

Determination of mixing-layer height by ground-based remote sensing  

NASA Astrophysics Data System (ADS)

Different ground-based remote sensing methods are today available to profile the boundary-layer and to derive such information as vertical layering and mixing-layer height (MLH). A SODAR detects the vertical profile of temperature fluctuations and gradients. By an algorithm which uses the acoustic backscatter intensity and the variance of the vertical velocity component estimates of the MLH can be made. A ceilometer detects the vertical distribution of aerosol particles and water droplets. By an algorithm which uses the vertical gradient of the optical backscatter intensity estimates of the MLH can be made. A RASS directly detects the vertical temperature profile and therefore allows for a direct measurement of MLH by analysing the vertical temperature gradient. In this presentation MLH determination from all three instruments will be compared and a few applications in the fields of air quality and wind energy will be presented. Limitations and restrictions of the different methods will be discussed.

Emeis, S.; Schäfer, K.; Münkel, C.

2009-09-01

171

Correlating Ground-Based Lightning Measurements with Ash Cloud Satellite Data from the 2010 Eruption of Eyjafjallajökull Volcano, Iceland  

NASA Astrophysics Data System (ADS)

Airborne volcanic ash is a major aviation hazard. For example, the 2010 eruption of Eyjafjallajökull volcano in Iceland resulted in the largest air-traffic shutdown since World War II. More than 100,000 flights were grounded, stranding passengers in Europe and across the globe, and producing a multi-billion dollar economic impact. Because of the high impact on aviation, sophisticated tools are needed to provide real-time alerts, tracking, and forecasting of volcanic clouds. In an attempt address the 5-minute volcanic cloud warning criteria established by the international aviation community, an automated volcanic cloud alert system for the Geostationary Operational Environmental Satellite - R Series (GOES-R) built upon the automated ash cloud alert system for the Advanced Very High Resolution Radiometer (AVHRR) is in development. The new system will be capable of identifying ash and SO2 clouds with greater accuracy. One component of GOES-R will be a lightning mapper. To study the temporal, spatial, and physical relationships between ash clouds and lightning, and the utility of lightning detection in a real-time alert system, we analyze data collected by the Lightning Mapping Array, a ground-based lightning detection network, in conjunction with satellite data gathered by the Spinning Enhanced Visible and Infrared Imager (SEVIRI) instrument aboard Meteosat-9 during in the 2010 eruption of Eyjafjallajökull volcano. We correlate lightning characteristics, intensity, and distribution with plume location, height, mass loading, and effective particle radius. Lightning mapping in volcanic ash clouds potentially will allow for better characterization of the ash cloud and aid in forecasting the distribution of ash and its effects on aviation.

McMahon, N. D.; Thomas, R. J.; Pavolonis, M. J.; Sieglaff, J.; Aster, R. C.

2012-12-01

172

Smart learning services based on smart cloud computing.  

PubMed

Context-aware technologies can make e-learning services smarter and more efficient since context-aware services are based on the user's behavior. To add those technologies into existing e-learning services, a service architecture model is needed to transform the existing e-learning environment, which is situation-aware, into the environment that understands context as well. The context-awareness in e-learning may include the awareness of user profile and terminal context. In this paper, we propose a new notion of service that provides context-awareness to smart learning content in a cloud computing environment. We suggest the elastic four smarts (E4S)--smart pull, smart prospect, smart content, and smart push--concept to the cloud services so smart learning services are possible. The E4S focuses on meeting the users' needs by collecting and analyzing users' behavior, prospecting future services, building corresponding contents, and delivering the contents through cloud computing environment. Users' behavior can be collected through mobile devices such as smart phones that have built-in sensors. As results, the proposed smart e-learning model in cloud computing environment provides personalized and customized learning services to its users. PMID:22164048

Kim, Svetlana; Song, Su-Mi; Yoon, Yong-Ik

2011-01-01

173

Smart Learning Services Based on Smart Cloud Computing  

PubMed Central

Context-aware technologies can make e-learning services smarter and more efficient since context-aware services are based on the user’s behavior. To add those technologies into existing e-learning services, a service architecture model is needed to transform the existing e-learning environment, which is situation-aware, into the environment that understands context as well. The context-awareness in e-learning may include the awareness of user profile and terminal context. In this paper, we propose a new notion of service that provides context-awareness to smart learning content in a cloud computing environment. We suggest the elastic four smarts (E4S)—smart pull, smart prospect, smart content, and smart push—concept to the cloud services so smart learning services are possible. The E4S focuses on meeting the users’ needs by collecting and analyzing users’ behavior, prospecting future services, building corresponding contents, and delivering the contents through cloud computing environment. Users’ behavior can be collected through mobile devices such as smart phones that have built-in sensors. As results, the proposed smart e-learning model in cloud computing environment provides personalized and customized learning services to its users. PMID:22164048

Kim, Svetlana; Song, Su-Mi; Yoon, Yong-Ik

2011-01-01

174

Designing the Cloud-based DOE Systems Biology Knowledgebase  

SciTech Connect

Systems Biology research, even more than many other scientific domains, is becoming increasingly data-intensive. Not only have advances in experimental and computational technologies lead to an exponential increase in scientific data volumes and their complexity, but increasingly such databases themselves are providing the basis for new scientific discoveries. To engage effectively with these community resources, integrated analyses, synthesis and simulation software is needed, regularly supported by scientific workflows. In order to provide a more collaborative, community driven research environment for this heterogeneous setting, the Department of Energy (DOE) has decided to develop a federated, cloud based cyber infrastructure - the Systems Biology Knowledgebase (Kbase). Pacific Northwest National Laboratory (PNNL) with its long tradition in data intensive science lead two of the five initial pilot projects, these two focusing on defining and testing the basic federated cloud-based system architecture and develop a prototype implementation. Hereby the community wide accessibility of biological data and the capability to integrate and analyze this data within its changing research context were seen as key technical functionalities the Kbase needed to enable. In this paper we describe the results of our investigations into the design of a cloud based federated infrastructure for: (1) Semantics driven data discovery, access and integration; (2) Data annotation, publication and sharing; (3) Workflow enabled data analysis; and (4) Project based collaborative working. We describe our approach, exemplary use cases and our prototype implementation that demonstrates the feasibility of this approach.

Lansing, Carina S.; Liu, Yan; Yin, Jian; Corrigan, Abigail L.; Guillen, Zoe C.; Kleese van Dam, Kerstin; Gorton, Ian

2011-09-01

175

Efficient resources provisioning based on load forecasting in cloud.  

PubMed

Cloud providers should ensure QoS while maximizing resources utilization. One optimal strategy is to timely allocate resources in a fine-grained mode according to application's actual resources demand. The necessary precondition of this strategy is obtaining future load information in advance. We propose a multi-step-ahead load forecasting method, KSwSVR, based on statistical learning theory which is suitable for the complex and dynamic characteristics of the cloud computing environment. It integrates an improved support vector regression algorithm and Kalman smoother. Public trace data taken from multitypes of resources were used to verify its prediction accuracy, stability, and adaptability, comparing with AR, BPNN, and standard SVR. Subsequently, based on the predicted results, a simple and efficient strategy is proposed for resource provisioning. CPU allocation experiment indicated it can effectively reduce resources consumption while meeting service level agreements requirements. PMID:24701160

Hu, Rongdong; Jiang, Jingfei; Liu, Guangming; Wang, Lixin

2014-01-01

176

STELLAR ENCOUNTERS WITH THE OORT CLOUD BASED ON HIPPARCOS DATA  

Microsoft Academic Search

We have combined Hipparcos proper-motion and parallax data for nearby stars with ground-based radial velocity measurements to —nd stars that may have passed (or will pass) close enough to the Sun to perturb the Oort cloud. Close stellar encounters could de—ect large numbers of comets into the inner solar system, which would increase the impact hazard at Earth. We —nd

DAVID W. LATHAM; ROBERT P. STEFANIK

177

Cloud based metalearning system for predictive modeling of biomedical data.  

PubMed

Rapid growth and storage of biomedical data enabled many opportunities for predictive modeling and improvement of healthcare processes. On the other side analysis of such large amounts of data is a difficult and computationally intensive task for most existing data mining algorithms. This problem is addressed by proposing a cloud based system that integrates metalearning framework for ranking and selection of best predictive algorithms for data at hand and open source big data technologies for analysis of biomedical data. PMID:24892101

Vuki?evi?, Milan; Radovanovi?, Sandro; Milovanovi?, Miloš; Minovi?, Miroslav

2014-01-01

178

Ground-Based Observations of Cloud Features on Uranus  

Microsoft Academic Search

NSFCAM observations at 1.7 ?m in 1998 and 1999 recorded the first discrete cloud features to appear in ground-based digital images of Uranus and the brightest such feature ever observed. The differential contributions of these northern hemisphere features to Uranus' disk-integrated brightness range from 0.8±0.2% and 0.11±0.3% for two 1998 features, to 4.9±0.7% for one 1999 feature, which is four

L. A. Sromovsky; J. R. Spencer; K. H. Baines; P. M. Fry

2000-01-01

179

Cloud Based Metalearning System for Predictive Modeling of Biomedical Data  

PubMed Central

Rapid growth and storage of biomedical data enabled many opportunities for predictive modeling and improvement of healthcare processes. On the other side analysis of such large amounts of data is a difficult and computationally intensive task for most existing data mining algorithms. This problem is addressed by proposing a cloud based system that integrates metalearning framework for ranking and selection of best predictive algorithms for data at hand and open source big data technologies for analysis of biomedical data. PMID:24892101

Vuki?evi?, Milan

2014-01-01

180

A Cloud Computing Based Patient Centric Medical Information System  

Microsoft Academic Search

\\u000a This chapter discusses an emerging concept of a cloud computing based Patient Centric Medical Information System framework\\u000a that will allow various authorized users to securely access patient records from various Care Delivery Organizations (CDOs)\\u000a such as hospitals, urgent care centers, doctors, laboratories, imaging centers among others, from any location. Such a system\\u000a must seamlessly integrate all patient records including images

Ankur Agarwal; Nathan Henehan; Vivek Somashekarappa; A. S. Pandya; Hari Kalva; Borko Furht

2010-01-01

181

A research on cloud computing based on IEEE1451  

Microsoft Academic Search

In view of the disadvantages of traditional measurement and control system, this article has proposed a cloud computing based on IEEE1451. It has defined the functions and goal of this system through the analysis of market demands, set up a hierarchical structure model, and established a software structure and application pattern with the combination of C\\/S structure and B\\/S structure.

Jian Wang; Peng Liu

2010-01-01

182

A Cloud Model Inference System Based Alpha-Beta Filter for Tracking of Maneuvering Target  

Microsoft Academic Search

An adaptive alpha-beta filter based on cloud model inference is presented for maneuvering target tracking. The proposed tracker incorporates cloud model in a conventional alpha-beta filter by using the rule bank based on cloud model, which utilizes the residue error and the change of residue error in the last prediction to determine the values of alpha and beta, then track

Jianjun Huang; Jiali Zhong; Pengfei Li

2010-01-01

183

Enforcing Trust-based Intrusion Detection in Cloud Computing Using Algebraic Methods  

E-print Network

Enforcing Trust-based Intrusion Detection in Cloud Computing Using Algebraic Methods Amira Bradai scheme for hybrid cloud computing is proposed. We consider a trust metric based on honesty, cooperation detection, Perron Frobenius, cloud computing, hybrid execution, false alarms, security scores. I

Paris-Sud XI, Université de

184

On Interference-aware Provisioning for Cloud-based Big Data Processing  

E-print Network

On Interference-aware Provisioning for Cloud-based Big Data Processing Yi YUAN, Haiyang WANG, Dan--Recent advances in cloud-based big data analysis offers a convenient mean for providing an elastic and cost and IBM deploy various of big data systems on their cloud platforms, aiming to occupy the huge market

Liu, Jiangchuan (JC)

185

A global survey of aerosol-liquid water cloud overlap based on four years of CALIPSO-CALIOP data  

NASA Astrophysics Data System (ADS)

The presence of aerosols over highly reflective liquid water cloud tops poses a big challenge in simulating their radiative impacts. Particularly, absorbing aerosols, such as smoke, may have significant impact in such situations and even change the sign of net radiative forcing. Until now, it was not possible to obtain information on such overlap events realistically from the existing passive satellite sensors. However, the CALIOP instrument onboard NASA's CALIPSO satellite allows us to examine these events with an unprecedented accuracy. Using four years of collocated CALIPSO 5 km Aerosol and Cloud Layer Version 3 Products (June 2006-May 2010), we quantify, for the first time, the macrophysical characteristics of overlapping aerosol and water cloud layers globally. We investigate seasonal variability in these characteristics over six latitude bands to understand the hemispheric differences. We compute a) the percentage cases when such overlap is seen globally and seasonally when all aerosol types are included (AAO case) in the analysis, b) the joint histograms of aerosol layer base height and cloud layer top height, and c) the joint histograms of aerosol and cloud geometrical thicknesses in such overlap cases. We also investigate frequency of smoke aerosol-cloud overlap (SAO case). The results show a distinct seasonality in overlap frequency in both AAO and SAO cases. Globally, the frequency is highest during JJA months in AAO case, while for the SAO case, it is highest in SON months. The seasonal mean overlap frequency can regionally exceed 20% in AAO case and 10% in SAO case. There is a tendency that the vertical separation between aerosol and cloud layers increases from high to low latitude regions in the both hemispheres. In about 5-10% cases the vertical distance between aerosol and cloud layers is less than 100 m, while about in 45-60% cases it less than a kilometer in the annual means for different latitudinal bands. The frequency of occurrence of thicker aerosol layers gradually increases from poles to tropics. In about 70-80% cases, aerosol layers are less than a kilometer thick, while in about 18-22% cases they are 1-2 km thick. The frequency of aerosol layers 2-3 km thick is about 4-5% in the tropical belts during overlap events. The results further highlight spatial and temporal variations in aerosol-liquid water cloud overlap and suggest that the frequency of occurrence of such overlap events is far from being negligible globally.

Devasthale, A.; Thomas, M. A.

2010-09-01

186

Policy-Based Event-Driven Services-Oriented Architecture for Cloud Services Operation & Management  

Microsoft Academic Search

Cloud based services, by their nature, are distributed and traditional operation and management processes that often exert centralized control are not suited for cloud services operation and management. This paper introduces a Policy-based Event-driven Service-oriented Architecture (PESA) that enables the manageability of these loosely coupled services distributed across multiple public or private clouds or a hybrid cloud. PESA allows the

Pankaj Goyal; Rao Mikkilineni

2009-01-01

187

Rule-based segmentation of LIDAR point cloud for automatic extraction of building roof planes  

NASA Astrophysics Data System (ADS)

This paper presents a new segmentation technique for LIDAR point cloud data for automatic extraction of building roof planes. Using the ground height from a DEM (Digital Elevation Model), the raw LIDAR points are separated into two groups: ground and nonground points. The ground points are used to generate a "building mask" in which the black areas represent the ground where there are no laser returns below a certain height. The non-ground points are segmented to extract the planar roof segments. First, the building mask is divided into small grid cells. The cells containing the black pixels are clustered such that each cluster represents an individual building or tree. Second, the non-ground points within a cluster are segmented based on their coplanarity and neighbourhood relations. Third, the planar segments are refined using a rule-based procedure that assigns the common points among the planar segments to the appropriate segments. Finally, another rule-based procedure is applied to remove tree planes which are small in size and randomly oriented. Experimental results on the Vaihingen data set show that the proposed method offers high building detection and roof plane extraction rates.

Awrangjeb, M.; Fraser, C. S.

2013-10-01

188

Cloud cover estimation: Use of GOES imagery in development of cloud cover data base for insolation assessment  

NASA Technical Reports Server (NTRS)

The potential of using digital satellite data to establish a cloud cover data base for the United States, one that would provide detailed information on the temporal and spatial variability of cloud development are studied. Key elements include: (1) interfacing GOES data from the University of Wisconsin Meteorological Data Facility with the Jet Propulsion Laboratory's VICAR image processing system and IBIS geographic information system; (2) creation of a registered multitemporal GOES data base; (3) development of a simple normalization model to compensate for sun angle; (4) creation of a variable size georeference grid that provides detailed cloud information in selected areas and summarized information in other areas; and (5) development of a cloud/shadow model which details the percentage of each grid cell that is cloud and shadow covered, and the percentage of cloud or shadow opacity. In addition, comparison of model calculations of insolation with measured values at selected test sites was accomplished, as well as development of preliminary requirements for a large scale data base of cloud cover statistics.

Huning, J. R.; Logan, T. L.; Smith, J. H.

1982-01-01

189

Cloud-Based Model Calibration Using OpenStudio: Preprint  

SciTech Connect

OpenStudio is a free, open source Software Development Kit (SDK) and application suite for performing building energy modeling and analysis. The OpenStudio Parametric Analysis Tool has been extended to allow cloud-based simulation of multiple OpenStudio models parametrically related to a baseline model. This paper describes the new cloud-based simulation functionality and presents a model cali-bration case study. Calibration is initiated by entering actual monthly utility bill data into the baseline model. Multiple parameters are then varied over multiple iterations to reduce the difference between actual energy consumption and model simulation results, as calculated and visualized by billing period and by fuel type. Simulations are per-formed in parallel using the Amazon Elastic Cloud service. This paper highlights model parameterizations (measures) used for calibration, but the same multi-nodal computing architecture is available for other purposes, for example, recommending combinations of retrofit energy saving measures using the calibrated model as the new baseline.

Hale, E.; Lisell, L.; Goldwasser, D.; Macumber, D.; Dean, J.; Metzger, I.; Parker, A.; Long, N.; Ball, B.; Schott, M.; Weaver, E.; Brackney, L.

2014-03-01

190

Influence of Subpixel Scale Cloud Top Structure on Reflectances from Overcast Stratiform Cloud Layers  

NASA Technical Reports Server (NTRS)

Recent observational studies have shown that satellite retrievals of cloud optical depth based on plane-parallel model theory suffer from systematic biases that depend on viewing geometry, even when observations are restricted to overcast marine stratus layers, arguably the closest to plane parallel in nature. At moderate to low sun elevations, the plane-parallel model significantly overestimates the reflectance dependence on view angle in the forward-scattering direction but shows a similar dependence in the backscattering direction. Theoretical simulations are performed that show that the likely cause for this discrepancy is because the plane-parallel model assumption does not account for subpixel, scale variations in cloud-top height (i.e., "cloud bumps"). Monte Carlo simulation, comparing ID model radiances to radiances from overcast cloud field with 1) cloud-top height variation, but constant cloud volume extinction; 2) flat tops but horizontal variations in cloud volume extinction; and 3) variations in both cloud top height and cloud extinction are performed over a approximately equal to 4 km x 4 km domain (roughly the size of an individual GAC AVHRR pixel). The comparisons show that when cloud-top height variations are included, departures from 1D theory are remarkably similar (qualitatively) to those obtained observationally. In contrast, when clouds are assumed flat and only cloud extinction is variable, reflectance differences are much smaller and do not show any view-angle dependence. When both cloud-top height and cloud extinction variations are included, however, large increases in cloud extinction variability can enhance reflectance difference. The reason 3D-1D reflectance differences are more sensitive to cloud-top height variations in the forward-scattering direction (at moderate to low, sun elevations) is because photons leaving the cloud field in that direction experience fewer scattering events (low-order scattering) and are restricted to the topmost portions of the cloud. While reflectance deviations from 1D theory are much larger for bumpy clouds than for flat clouds with variable cloud extinction, differences in cloud albedo are comparable for these two cases.

Loeb, N. G.; Varnai, Tamas; Winker, David M.

1998-01-01

191

Research of streaming media services based on cloud computing  

NASA Astrophysics Data System (ADS)

In order to solve the problem of mass concurrent access to streaming media, this paper designs the application of streaming media services based on cloud computing with technologies about cloud computing. With the analysis of the actual demand, the system the paper designs includes three parts: streaming media resource center, streaming media edge node and intelligent load balance system. Streaming media resource center could manage and distribute streaming media resources; streaming media edge node is responsible for replaying requests of streaming media playing directly; intelligent load balance system would schedule system loads according to the current state of users requests automatically. After experiments, it proves that the system has good performance and practical value.

Wang, Zongbin

2012-04-01

192

Space Science Cloud: a Virtual Space Science Research Platform Based on Cloud Model  

NASA Astrophysics Data System (ADS)

Through independent and co-operational science missions, Strategic Pioneer Program (SPP) on Space Science, the new initiative of space science program in China which was approved by CAS and implemented by National Space Science Center (NSSC), dedicates to seek new discoveries and new breakthroughs in space science, thus deepen the understanding of universe and planet earth. In the framework of this program, in order to support the operations of space science missions and satisfy the demand of related research activities for e-Science, NSSC is developing a virtual space science research platform based on cloud model, namely the Space Science Cloud (SSC). In order to support mission demonstration, SSC integrates interactive satellite orbit design tool, satellite structure and payloads layout design tool, payload observation coverage analysis tool, etc., to help scientists analyze and verify space science mission designs. Another important function of SSC is supporting the mission operations, which runs through the space satellite data pipelines. Mission operators can acquire and process observation data, then distribute the data products to other systems or issue the data and archives with the services of SSC. In addition, SSC provides useful data, tools and models for space researchers. Several databases in the field of space science are integrated and an efficient retrieve system is developing. Common tools for data visualization, deep processing (e.g., smoothing and filtering tools), analysis (e.g., FFT analysis tool and minimum variance analysis tool) and mining (e.g., proton event correlation analysis tool) are also integrated to help the researchers to better utilize the data. The space weather models on SSC include magnetic storm forecast model, multi-station middle and upper atmospheric climate model, solar energetic particle propagation model and so on. All the services above-mentioned are based on the e-Science infrastructures of CAS e.g. cloud storage and cloud computing. SSC provides its users with self-service storage and computing resources at the same time.At present, the prototyping of SSC is underway and the platform is expected to be put into trial operation in August 2014. We hope that as SSC develops, our vision of Digital Space may come true someday.

Hu, Xiaoyan; Tong, Jizhou; Zou, Ziming

193

Measuring the accuracy of self-reported height and weight in a community-based sample of young people  

PubMed Central

Background Self-reported anthropometric data are commonly used to estimate prevalence of obesity in population and community-based studies. We aim to: 1) Determine whether survey participants are able and willing to self-report height and weight; 2) Assess the accuracy of self-reported compared to measured anthropometric data in a community-based sample of young people. Methods Participants (16–29 years) of a behaviour survey, recruited at a Melbourne music festival (January 2011), were asked to self-report height and weight; researchers independently weighed and measured a sub-sample. Body Mass Index was calculated and overweight/obesity classified as ?25kg/m2. Differences between measured and self-reported values were assessed using paired t-test/Wilcoxon signed ranks test. Accurate report of height and weight were defined as <2cm and <2kg difference between self-report and measured values, respectively. Agreement between classification of overweight/obesity by self-report and measured values was assessed using McNemar’s test. Results Of 1405 survey participants, 82% of males and 72% of females self-reported their height and weight. Among 67 participants who were also independently measured, self-reported height and weight were significantly less than measured height (p=0.01) and weight (p<0.01) among females, but no differences were detected among males. Overall, 52% accurately self-reported height, 30% under-reported, and 18% over-reported; 34% accurately self-reported weight, 52% under-reported and 13% over-reported. More females (70%) than males (35%) under-reported weight (p=0.01). Prevalence of overweight/obesity was 33% based on self-report data and 39% based on measured data (p=0.16). Conclusions Self-reported measurements may underestimate weight but accurately identified overweight/obesity in the majority of this sample of young people. PMID:23170838

2012-01-01

194

Toward Understanding of Differences in Current Cloud Retrievals of ARM Ground-based Measurements  

SciTech Connect

Accurate observations of cloud microphysical properties are needed for evaluating and improving the representation of cloud processes in climate models. However, large differences are found in current cloud products retrieved from ground-based remote sensing measurements using various retrieval algorithms. Understanding the differences is an important step to address uncertainties in the cloud retrievals. In this study, an in-depth analysis of nine existing ground-based cloud retrievals using ARM remote sensing measurements is carried out. We place emphasize on boundary layer overcast clouds and high level ice clouds, which are the focus of many current retrieval development efforts due to their radiative importance and relatively simple structure. Large systematic discrepancies in cloud microphysical properties are found in these two types of clouds among the nine cloud retrieval products, particularly for the cloud liquid and ice effective radius. It is shown that most of these large differences have their roots in the retrieval algorithms used by these cloud products, including the retrieval theoretical bases, assumptions, as well as input and constraint parameters. This study suggests the need to further validate current retrieval theories and assumptions and even the development of new retrieval algorithms with more observations under different cloud regimes.

Zhao, Chuanfeng; Xie, Shaocheng; Klein, Stephen A.; Protat, Alain; Shupe, Matthew D.; McFarlane, Sally A.; Comstock, Jennifer M.; Delanoe, Julien; Deng, Min; Dunn, Maureen; Hogan, Robin; Huang, Dong; Jensen, Michael; Mace, Gerald G.; McCoy, Renata; O'Conner, Ewan J.; Turner, Dave; Wang, Zhien

2012-05-30

195

Ground-Based Observations of Clouds in the Arctic --  

E-print Network

/05-present 1) Observation of Mixed-Phase Stratus clouds 70 N 80 N #12;CloudSAT Science Team Meeting, Seattle-Phase Stratus clouds 2) Representativeness of "point" comparisons 70 N 80 N #12;CloudSAT Science Team Meeting, Seattle,WA 19-21 August, 2008 Introduction: Mixed-Phase Stratus Time (UT) Altitude(km) dar backscatter

Eloranta, Edwin W.

196

Research of campus resource management based on cloud computing  

Microsoft Academic Search

Cloud computing is low-cost, high-performance network application model, is gradually affecting study, work and life of people. This article introduces cloud computing and function of cloud computing, then analyzes the exiting problems of campus network resource management, the cloud computing technology and methods are applied in the construction of college information sharing platform, which can not only improve the utilization

Liu Xuning; Song Hongwei; He Dongbin; Yang Hao

2010-01-01

197

Phase-Based Application-Driven Hierarchical Power Management on the Single-chip Cloud Computer  

E-print Network

Phase-Based Application-Driven Hierarchical Power Management on the Single-chip Cloud Computer consumption on-the- fly. Many-core architectures, such as the Single-chip Cloud Computer (SCC) experimental' Single-chip Cloud Computer (SCC) experimental processor [10], a 48- core "concept vehicle" created

Singer, Jeremy

198

Insurance-Based Cloud Computing-Architecture, Risk Analysis and Experiment  

Microsoft Academic Search

By adopting the idea of insurance business in our real life, an insurance-based cloud computing architecture is proposed in this paper to rebuild a monetary credit system for cloud computing. In this architecture, insurer agents are introduced to offer paid guarantee for services in cloud computing, and to compensate Internet users when the services invoked fail. Then, regarding to the

Changli Zhang; Maode Yan

2010-01-01

199

MISR Cloud Detection over Ice and Snow Based on Linear Correlation Matching  

E-print Network

; Nakamura and Oort, 1988), but others studies suggest clouds have a net cooling effect (Li and LeightonMISR Cloud Detection over Ice and Snow Based on Linear Correlation Matching Tao Shi , Bin Yu , and Amy Braverman Abstract Cloud detection is a crucial step in any climate modelling or prediction

Sekhon, Jasjeet S.

200

Cloud Study Investigators: Using NASA's CERES S'COOL in Problem-Based Learning  

ERIC Educational Resources Information Center

1This article describes how, by incorporating NASA's Students' Cloud Observations On-Line (S'COOL) project into a problem-based learning (PBL) activity, middle school students are engaged in authentic scientific research where they observe and record information about clouds and contribute ground truth data to NASA's Clouds and the Earth's…

Moore, Susan; Popiolkowski, Gary

2011-01-01

201

KNOWLEDGE REPRESENTATION AND UNCERTAINTY REASONING IN GIS BASED ON CLOUD MODELS  

Microsoft Academic Search

The cloud model and its extensions are desc ribed and used in knowledge representation and uncertainty reasoning in GIS. A series of uncertainty reasoning algorithms are proposed based on cloud models. The digital characteristics of clouds well integrate the fuzziness and randomness of linguistic terms in a unified way, which lays a foundation of knowledge representation. The new uncertainty reasoning

Deren Li; Kaichang Di; Deyi Li

202

An Implementation of Embedded Geographic Information System Based on Cloud Computing  

Microsoft Academic Search

An implementation of embedded geographic information system is proposed based on cloud computing mode. With cloud computing, the newest geographic information can be gotten in the terminal, meanwhile, good mobility and real-time performance can be obtained. MapX is used in cloud server to accomplish the integrated developing of GIS server. The geographic information is located there, so that it is

Yiqin Lu; Kanghua Yu; Yuan Liu

2011-01-01

203

2013 Faculty Publications A Cloud-Based Framework for Automating MODFLOW Simulations for Aquifer Management  

E-print Network

Conference. Jim Nelson. Essential GIS Technologies for Hydrologic Simulation Applications in Cloud Computing2013 Faculty Publications A Cloud-Based Framework for Automating MODFLOW Simulations for Aquifer- Dimensional Modeling in the Cloud. Proceedings of the American Society of Civil Engineers (ASCE) Environmental

Olsen Jr., Dan R.

204

COMBAT: mobile-Cloud-based cOmpute/coMmunications infrastructure for BATtlefield applications  

E-print Network

to this explosive growth in data, a substantial increase in mobile compute-capability and the advances in cloud computing have brought the state-of- the-art in mobile-cloud computing to an inflection point, where computing. In this paper, we propose the MObile Cloud-based Hybrid Architecture (MOCHA), which formulates

Kwon, Minseok "James"

205

CloudSat Preps for Launch at Vandenberg Air Force Base, CA  

NASA Technical Reports Server (NTRS)

The CloudSat spacecraft sits encapsulated within its Boeing Delta launch vehicle dual payload attach fitting at Vandenberg Air Force Base, Calif. CloudSat will share its ride to orbit late next month with NASA's CALIPSO spacecraft. The two spacecraft are designed to reveal the secrets of clouds and aerosols.

2005-01-01

206

A Time-series Pattern based Noise Generation Strategy for Privacy Protection in Cloud Computing  

E-print Network

A Time-series Pattern based Noise Generation Strategy for Privacy Protection in Cloud Computing of Technology, Sydney Broadway, NSW, Australia 2007 Jinjun.Chen@uts.edu.au Abstract--Cloud computing promises of cloud computing security, there is a need to take special actions to protect privacy at client sides

Yang, Yun

207

MDP Based Optimal Pricing for a Cloud Computing Queueing Rami Atar Israel Cidon Mark Shifrin  

E-print Network

MDP Based Optimal Pricing for a Cloud Computing Queueing Model Rami Atar Israel Cidon Mark Shifrin] and especially cloud computing services at both consumer and enterprise markets [12], [18]. Previous MDP formulations for cloud computing applications can be found in [13] and [14]. These works optimize the decision

Atar, Rami

208

Privacy-Preserving Data Publish-Subscribe Service on Cloud-based Platforms  

E-print Network

publication and subscription. However, the privacy becomes a challenging issue as the cloud server cannot infrastructures and tools. Cloud computing, as an emerging technique, can provide eco- nomic but powerful storage1 Privacy-Preserving Data Publish-Subscribe Service on Cloud-based Platforms Kan Yang, Xiaohua Jia

209

A cost-effective mechanism for Cloud data reliability management based on proactive replica checking  

E-print Network

A cost-effective mechanism for Cloud data reliability management based on proactive replica present a novel cost-effective data reliability management mechanism named PRCR, which proactively checks checking, data reliability, cost-effective storage, Cloud computing I. INTRODUCTION The size of Cloud

Yang, Yun

210

Cloud Computing Based Technologies, Applications and Structure in U-learning  

Microsoft Academic Search

This article mainly focuses on the characteristic, technologies and applications of cloud computing in mobile and electronic learning, and analyzes the features of this concept. We firstly tried to clarify the meaning of cloud computing as well as its features, secondly, proposed different models of using cloud computing in different learning environments, including web-based learning, mobile video learning and observational

Aida Ghazizadeh; Maziar Manouchehry

2012-01-01

211

Experimental Analysis of Task-based Energy Consumption in Cloud Computing Systems  

E-print Network

Experimental Analysis of Task-based Energy Consumption in Cloud Computing Systems Feifei Chen, John}@swin.edu.au ABSTRACT Cloud computing delivers IT solutions as a utility to users. One consequence of this model. We have developed an energy consumption model for cloud computing systems. To operationalise

Schneider, Jean-Guy

212

Trace-Based Analysis and Prediction of Cloud Computing User Behavior Using the Fractal Modeling Technique  

E-print Network

Trace-Based Analysis and Prediction of Cloud Computing User Behavior Using the Fractal Modeling and technology. In this paper, we investigate the characteristics of the cloud computing requests received the alpha- stable distribution. Keywords- cloud computing; alpha-stable distribution; fractional order

Pedram, Massoud

213

An Optimal Control Policy in a Mobile Cloud Computing System Based on Stochastic Data  

E-print Network

An Optimal Control Policy in a Mobile Cloud Computing System Based on Stochastic Data Xue Lin Angeles, CA, USA {xuelin, yanzhiwa, pedram}@usc.edu Abstract--The emerging mobile cloud computing (MCC sum. Keywords--mobile cloud computing; remote processing; dynamic voltage and frequency scaling I

Pedram, Massoud

214

A Nested Two Stage Game-Based Optimization Framework in Mobile Cloud Computing System  

E-print Network

A Nested Two Stage Game-Based Optimization Framework in Mobile Cloud Computing System Yanzhi Wang Angeles, USA {yanzhiwa, xuelin, pedram}@usc.edu Abstract--The rapidly developing cloud computing to offload computation and which portion of application should be offloaded to the cloud. In this paper, we

Pedram, Massoud

215

Use of satellite remote sensing for determining cloud immersion and biogeography of cloud forests  

NASA Astrophysics Data System (ADS)

Tropical montane cloud forests (TMCFs) are ecosystems characterized by frequent and prolonged immersion in orographic clouds. TMCFs are biologically rich and diverse and they lie at the core of several of the global biological hotspots identified for conservation purposes. Recent studies show that TMCFs are sensitive to global and regional scale climate changes. Vegetation in TMCFs directly harvest water from clouds, which is usually termed horizontal precipitation, and is an important input to local hydrological cycle. Mosses and ferns present within the TMCFs absorbs moisture during rainfall and releases slowly over time thereby providing another important hydrological function, namely modulation of runoff. In spite of the ecological and hydrological importance of TMCFs, there is scant information regarding the geographical distribution of the TMCFs. One source of information that is currently available is the atlas of the potential cloud forest distribution published by the United Nations Environmental Program. However, this compilation does not directly consider the defining characteristics of cloud forests, namely frequency of immersion in cloud forests, in their classisification scheme. This talk will present the use of NASA MODIS satellite data to determine cloud immersion frequency and thus the biogeography of cloud forests. The MODIS derived cloud top heights and cloud thickness estimated from MODIS retrieval of cloud microphysical properties is used to estimate cloud base height. If the estimate cloud base height at a location is less than or equal to the surface elevation at that point, then that location is defined as experiencing cloud immersion. This classification procedure was applied to determine cloud immersion frequency at two study sites, namely Hawaii and Monteverde, Costa Rica. The cloud immersion frequency maps identifies some of the know cloud forest locations in these study areas. Comparison against a blended product created using numerical modeling and geostationary satellite data also show good agreement over Monteverde, Costa Rica.

Asefi Najafabady, S.; Welch, R. M.; Nair, U.; Lawton, R. O.; Ray, D.

2006-12-01

216

Remote Sensing of Aerosol and Cloud Properties from Ground Based and Satellite Remote Sensors to Explore Aerosol-Cloud Interaction  

NASA Astrophysics Data System (ADS)

The measurements of both aerosol and cloud properties are critical for climate studies since these mechanisms have the largest uncertainty in energy balance calculations. In addition, aerosols and clouds do not act independently but can significantly couple to each other. It is clear that being able to quantify these interactions is crucial to climate models. While there are many possible aerosol-cloud interactions, we limit our investigation to the Twomey indirect effect which relates how aerosols can modify the physical properties of clouds thereby changing the radiative properties. Verifying and quantifying such mechanisms on a global scale requires accurate measurements of both aerosols and clouds from satellites. Unfortunately, assessing this mechanism has been very difficult from satellites since both aerosols and cloud properties would have to be simultaneously measured. Therefore, only statistical approaches have been tried but it is easy to see that such approaches will tend to obscure the interpretation of local interaction mechanisms. In this thesis, we investigate the potential of both satellites and ground based approaches to measure Aerosol Cloud Interaction parameters. After assessing the limitations of satellite based approaches, we focus on the use of ground based remote sensing using a combination of Lidar, Microwave radiometry, Doppler Lidar and sky radiometry. This instrumentation suite offers a more direct approach that can probe the properties of both aerosols and clouds simultaneously allowing us to investigate real time aerosol-cloud processes which occur on time scale < 1 minute. To this end, we first provide a thorough description of the multi-sensor approach and how it can be implemented including a sensitivity analysis taking into account both atmospheric and surface variability as well as uncertainty in both the Liquid Water Path (LWP) and diffuse transmittance measurements. In addition, we use the Southern Great Plain (SGP) data to test our cloud parameter inversion algorithm against other algorithms. In addition, we illustrate the need to account for aloft aerosols in observations of aerosol cloud interactions. Finally, we describe how the CCNY site may ultimately be used for further improve ground observations of aerosol cloud interactions.

He, Yuzhe

217

Estimating high quantiles of extreme flood heights in the lower Limpopo River basin of Mozambique using model based Bayesian approach  

NASA Astrophysics Data System (ADS)

In this paper we discuss a comparative analysis of the maximum likelihood (ML) and Bayesian parameter estimates of the generalised extreme value (GEV) distribution. We use a Markov Chain Monte Carlo (MCMC) Bayesian method to estimate the parameters of the GEV distribution in order to estimate extreme flood heights and their return periods in the lower Limpopo River basin of Mozambique. The return periods of extreme flood heights based on the Bayesian approach show an improvement over the frequentist approach based on the maximum likelihood estimation (MLE) method. However, both approaches indicate that the 13 m extreme flood height that occurred at Chokwe in the year 2000 due to cyclone Eline and Gloria had a return period in excess of 200 years, which implies that this event has a very small likelihood of being equalled or exceeded at least once in 200 years.

Maposa, D.; Cochran, J. J.; Lesaoana, M.; Sigauke, C.

2014-08-01

218

Toward understanding of differences in current cloud retrievals of ARM ground-based measurements  

SciTech Connect

Accurate observations of cloud microphysical properties are needed for evaluating and improving the representation of cloud processes in climate models and better estimate of the Earth radiative budget. However, large differences are found in current cloud products retrieved from ground-based remote sensing measurements using various retrieval algorithms. Understanding the differences is an important step to address uncertainties in the cloud retrievals. In this study, an in-depth analysis of nine existing ground-based cloud retrievals using ARM remote sensing measurements is carried out. We place emphasis on boundary layer overcast clouds and high level ice clouds, which are the focus of many current retrieval development efforts due to their radiative importance and relatively simple structure. Large systematic discrepancies in cloud microphysical properties are found in these two types of clouds among the nine cloud retrieval products, particularly for the cloud liquid and ice particle effective radius. Note that the differences among some retrieval products are even larger than the prescribed uncertainties reported by the retrieval algorithm developers. It is shown that most of these large differences have their roots in the retrieval theoretical bases, assumptions, as well as input and constraint parameters. This study suggests the need to further validate current retrieval theories and assumptions and even the development of new retrieval algorithms with more observations under different cloud regimes.

Zhao C.; Dunn M.; Xie, S.; Klein, S. A.; Protat, A.; Shupe, M. D.; McFarlane, S. A.; Comstock, J. M.; Delanoë, J.; Deng, M.; Hogan, R. J.; Huang, D.; Jensen, M. P.; Mace, G. G.; McCoy, R.; O’Connor, E. J.; Turner, D. D.; Wang, Z.

2012-05-30

219

Cloud Computing Titel: Cloud-based Parallel Computing for Unstructured Information Processing Reference  

E-print Network

Nowadays, the increasing amount of collaboratively created content is hardly accessible for analysis with traditional technology because it is normally unstructured information. At the same time such content becomes more and more business relevant because it is heavily used in daily work processes and business decision making.The ability to link documents with weakly structured and structured information allows a new generation of sensemaking algorithms to extract meaning from a nearly unmanageable amount of data.For this reason, SAP Research is working towards an internal project to extract meaning from unstructured data using semantic technologies. Because of the huge amount of source data, the motivation of this thesis is to accelerate the unstructured information processing by using the cloud-based technologies. In additional, the SLA (Service Level Agreement) will also be introduced to fulfill the potential business requirements.

Masterthesis Tong Lin; Aufgabensteller Prof; Dr. Florian Matthes; Bearbeiter Tong Lin; Sascha Roth

2010-01-01

220

Importance of aggregation and small ice crystals in cirrus clouds, based on observations and an ice particle growth model  

NASA Technical Reports Server (NTRS)

The 1 November 1986 FIRE I case study was used to test an ice particle growth model which predicts bimodal size spectra in cirrus clouds. The model was developed from an analytically based model which predicts the height evolution of monomodal ice particle size spectra from the measured ice water content (IWC). Size spectra from the monomodal model are represented by a gamma distribution, N(D) = N(sub o)D(exp nu)exp(-lambda D), where D = ice particle maximum dimension. The slope parameter, lambda, and the parameter N(sub o) are predicted from the IWC through the growth processes of vapor diffusion and aggregation. The model formulation is analytical, computationally efficient, and well suited for incorporation into larger models. The monomodal model has been validated against two other cirrus cloud case studies. From the monomodal size spectra, the size distributions which determine concentrations of ice particles less than about 150 mu m are predicted.

Mitchell, David L.; Chai, Steven K.; Dong, Yayi; Arnott, W. Patrick; Hallett, John

1993-01-01

221

Video-based real-time measurement for human body height  

NASA Astrophysics Data System (ADS)

Height measurement for a moving human body is a hard task for human body estimation. We propose a novel algorithm for real-time human height measurement without knowing any camera parameter, just having a vertical reference height. As contrasted with the previous research methods in the context of camera calibration, the studied algorithm reduces the complexity of user operations and the economy cost. First, three or more pairs of top-points and bottom-points are extracted by detecting the moving human body to solve the vertical vanishing point and the horizontal vanishing line. Then, the height of the moving human body on ground plane or stepped plane is obtained using the solved vanishing point, the vanishing line, and a given reference height. Considering the importance of the vanishing point and the vanishing line and the sensitivity of both to noise, an optimal approach is adopted. Finally, we show the optimal number and position of the human body in a camera field. Both computer simulation and real testing data validate the robustness and the effectiveness of the proposed algorithm.

Li, Weisheng; Wang, Weixing; Gao, Hongbo; Zhang, Licheng

2012-08-01

222

Height Museum  

NSDL National Science Digital Library

In this activity, children use strips of paper cut to their height to make comparisons. They are asked to make predictions such as "Is the oldest student the tallest?" and then check their predictions. A suggested variation is to predict changes in height over time by repeating the exercise in three months.

2010-01-01

223

Building Height  

NSDL National Science Digital Library

Working in pairs, students create a clinometer and use isosceles right triangles to find the height of a building. The class will compare measurements, discuss their results, and select the best measure of central tendency to report the most accurate height. All handouts and excellent class discussion questions are provided.

Hendrickson, Katie

2000-01-01

224

An expert fitness diagnosis system based on elastic cloud computing.  

PubMed

This paper presents an expert diagnosis system based on cloud computing. It classifies a user's fitness level based on supervised machine learning techniques. This system is able to learn and make customized diagnoses according to the user's physiological data, such as age, gender, and body mass index (BMI). In addition, an elastic algorithm based on Poisson distribution is presented to allocate computation resources dynamically. It predicts the required resources in the future according to the exponential moving average of past observations. The experimental results show that Naïve Bayes is the best classifier with the highest accuracy (90.8%) and that the elastic algorithm is able to capture tightly the trend of requests generated from the Internet and thus assign corresponding computation resources to ensure the quality of service. PMID:24723842

Tseng, Kevin C; Wu, Chia-Chuan

2014-01-01

225

An Expert Fitness Diagnosis System Based on Elastic Cloud Computing  

PubMed Central

This paper presents an expert diagnosis system based on cloud computing. It classifies a user's fitness level based on supervised machine learning techniques. This system is able to learn and make customized diagnoses according to the user's physiological data, such as age, gender, and body mass index (BMI). In addition, an elastic algorithm based on Poisson distribution is presented to allocate computation resources dynamically. It predicts the required resources in the future according to the exponential moving average of past observations. The experimental results show that Naïve Bayes is the best classifier with the highest accuracy (90.8%) and that the elastic algorithm is able to capture tightly the trend of requests generated from the Internet and thus assign corresponding computation resources to ensure the quality of service. PMID:24723842

Tseng, Kevin C.; Wu, Chia-Chuan

2014-01-01

226

Deriving the effective scale height in the topside ionosphere based on ionosonde and satellite in situ observations  

NASA Astrophysics Data System (ADS)

scale height is a valuable key parameter measuring the shape of the profile of plasma density in the F2 layer ionosphere. Currently, the data of Chapman scale height are routinely derived from ionogram observations at many ionosonde stations in terms of the SAO explorer software. In this report, we collected the in situ observations of plasma density at altitudes around 600 km from the ROCSAT-1 satellite and of simultaneous F peak parameters from an ionosonde operated at Wuhan (30.6°N, 114.4°E), a low-latitude station in central China, to estimate the topside plasma density profiles by using the Chapman ? function and further retrieve Chapman scale height. Evident solar cycle, seasonal variation, and local time variation are presented in the retrieved Chapman scale height over Wuhan. The climatological features of the derived Chapman scale height are significantly different from those from the ground-based ionograms. Such significant discrepancy suggests that further improvements are required in the present extrapolating topside electron density profiles from ionosonde observations. Furthermore, the attempt to constructing plasma density profiles through combining ionosonde and satellite in situ observations provides a new way to reanalyze observations from different sources and normalize plasma density recorded at varying altitudes to specified altitudes, which is critical and more convenient for ionospheric climatology studies.

Liu, Libo; Huang, He; Chen, Yiding; Le, Huijun; Ning, Baiqi; Wan, Weixing; Zhang, Hui

2014-10-01

227

Comparison of CERES-MODIS Stratus Cloud Properties with Ground-Based Measurements at the DOE ARM Southern Great Plains Site  

NASA Technical Reports Server (NTRS)

Overcast stratus cloud properties derived for the Clouds and the Earth's Radiant Energy system (CERES) Project using Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) data are compared with observations taken at the Atmospheric Radiation Measurement (ARM) Southern Great Plains site from March 2000 through December 2004. Retrievals from ARM surface-based data were averaged over a 1-hour interval centered at the time of each satellite overpass, and the CERES-MODIS cloud properties were averaged within a 30-km x 30 km box centered on the ARM SGP site. Two datasets were analyzed: all of the data (ALL) which include multilayered, single-layered, and slightly broken stratus decks and a subset, single-layered unbroken decks (SL). The CERES-MODIS effective cloud heights were determined from effective cloud temperature using a lapse rate method with the surface temperature specified as the 24-h mean surface air temperature. For SL stratus, they are, on average, within the ARM radar-lidar estimated cloud boundaries and are 0.534 +/- 0.542 km and 0.108 +/- 0.480 km lower than the cloud physical tops and centers, respectively, and are comparable for day and night observations. The mean differences and standard deviations are slightly larger for ALL data, but not statistically different to those of SL data. The MODIS-derived effective cloud temperatures are 2.7 +/- 2.4 K less than the surface-observed SL cloud center temperatures with very high correlations (0.86-0.97). Variations in the height differences are mainly caused by uncertainties in the surface air temperatures, lapse rates, and cloud-top height variability. The biases are mainly the result of the differences between effective and physical cloud top, which are governed by cloud liquid water content and viewing zenith angle, and the selected lapse rate, -7.1 K km(exp -1). Based on a total of 43 samples, the means and standard deviations of the differences between the daytime Terra and surface retrievals of effective radius r(sub e), optical depth, and liquid water path for SL stratu are 0.1 +/- 1.9 micrometers (1.2 +/- 23.5%), -1.3 +/- 9.5 (-3.6 +/-26.2%), and 0.6 +/- 49.9 gm (exp -2) (0.3 +/- 27%), respectively, while the corresponding correlation coefficients are 0.44, 0.87, and 0.89. For Aqua, they are 0.2 +/- 1.9 micrometers (2.5 +/- 23.4%), 2.5 +/- 7.8 (7.8 +/- 24.3%), and 28.1 +/- 52.7 gm (exp -2) (17.2 +/- 32.2%), as well as 0.35, 0.96, and 0.93 from a total of 21 cases. The results for ALL cases are comparable. Although a bias in R(sub e) was expected because the satellite retrieval of effective radius only represents the top of the cloud, the surface-based radar retrievals revealed that the vertical profile of r(sub e) is highly variable with smaller droplets occurring at cloud top in some cases. The larger bias in optical depth and liquid water path for Aqua is due, at least partially, to differences in the Terra and Aqua MODIS visible channel calibrations. methods for improving the cloud-top height and microphysical property retrievals are suggested.

Dong, Xiquan; Minnis Patrick; Xi, Baike; Sun-Mack, Sunny; Chen, Yan

2008-01-01

228

A cloud computing based 12-lead ECG telemedicine service  

PubMed Central

Background Due to the great variability of 12-lead ECG instruments and medical specialists’ interpretation skills, it remains a challenge to deliver rapid and accurate 12-lead ECG reports with senior cardiologists’ decision making support in emergency telecardiology. Methods We create a new cloud and pervasive computing based 12-lead Electrocardiography (ECG) service to realize ubiquitous 12-lead ECG tele-diagnosis. Results This developed service enables ECG to be transmitted and interpreted via mobile phones. That is, tele-consultation can take place while the patient is on the ambulance, between the onsite clinicians and the off-site senior cardiologists, or among hospitals. Most importantly, this developed service is convenient, efficient, and inexpensive. Conclusions This cloud computing based ECG tele-consultation service expands the traditional 12-lead ECG applications onto the collaboration of clinicians at different locations or among hospitals. In short, this service can greatly improve medical service quality and efficiency, especially for patients in rural areas. This service has been evaluated and proved to be useful by cardiologists in Taiwan. PMID:22838382

2012-01-01

229

Three-dimensional geospatial information service based on cloud computing  

NASA Astrophysics Data System (ADS)

Cloud computing technologies can support high-performance geospatial services in various domains, such as smart city and agriculture. Apache Hadoop, an open-source software framework, can be used to build a cloud environment on commodity clusters for storage and large-scale processing of data sets. The Open Geospatial Consortium (OGC) Web 3-D Service (W3DS) is a portrayal service for three-dimensional (3-D) geospatial data. Its performance could be improved by cloud computing technologies. This paper investigates how OGC W3DS could be developed in a cloud computing environment. It adopts the Apache Hadoop as the framework to provide a cloud implementation. The design and implementation of the 3-D geospatial information cloud service is presented. The performance evaluation is performed over data retrieval tests running in a cloud platform built by Hadoop clusters. The evaluation results provide a valuable reference on providing high-performance 3-D geospatial information cloud services.

Zhai, Xi; Yue, Peng; Jiang, Liangcun; Wang, Linnan

2014-01-01

230

Simulation of IR cloud background based on aircraft data  

NASA Astrophysics Data System (ADS)

Through thermal emission and scattered solar radiation, clouds present a significant clutter source to infrared surveillance sensors viewing from space. This program has generated IR cloud background scenes through modeling the thermal emission and scattering of the sun, which does so by combining the blackbody thermal emissions at cloud altitudes with solar radiation scattered from the cloud's top surface, and also takes as inputs descriptions of the incident solar radiance, along with sky shine and path radiance,. using NASA's ER-2 HIS data.

Wu, Kaifeng; Lu, Yihuai; Liu, Xingrun; Mao, Hongxia; Ma, Jing

2014-11-01

231

Comparison of Cloud Properties from CALIPSO-CloudSat and Geostationary Satellite Data  

NASA Technical Reports Server (NTRS)

Cloud properties are being derived in near-real time from geostationary satellite imager data for a variety of weather and climate applications and research. Assessment of the uncertainties in each of the derived cloud parameters is essential for confident use of the products. Determination of cloud amount, cloud top height, and cloud layering is especially important for using these real -time products for applications such as aircraft icing condition diagnosis and numerical weather prediction model assimilation. Furthermore, the distribution of clouds as a function of altitude has become a central component of efforts to evaluate climate model cloud simulations. Validation of those parameters has been difficult except over limited areas where ground-based active sensors, such as cloud radars or lidars, have been available on a regular basis. Retrievals of cloud properties are sensitive to the surface background, time of day, and the clouds themselves. Thus, it is essential to assess the geostationary satellite retrievals over a variety of locations. The availability of cloud radar data from CloudSat and lidar data from CALIPSO make it possible to perform those assessments over each geostationary domain at 0130 and 1330 LT. In this paper, CloudSat and CALIPSO data are matched with contemporaneous Geostationary Operational Environmental Satellite (GOES), Multi-functional Transport Satellite (MTSAT), and Meteosat-8 data. Unlike comparisons with cloud products derived from A-Train imagers, this study considers comparisons of nadir active sensor data with off-nadir retrievals. These matched data are used to determine the uncertainties in cloud-top heights and cloud amounts derived from the geostationary satellite data using the Clouds and the Earth s Radiant Energy System (CERES) cloud retrieval algorithms. The CERES multi-layer cloud detection method is also evaluated to determine its accuracy and limitations in the off-nadir mode. The results will be useful for constraining the use of the passive retrieval data in models and for improving the accuracy of the retrievals.

Nguyen, L.; Minnis, P.; Chang, F.; Winker, D.; Sun-Mack, S.; Spangenberg, D.; Austin, R.

2007-01-01

232

Cloud optical thickness retrievals from ground-based pyranometer measurements  

NASA Astrophysics Data System (ADS)

A method is developed to retrieve total cloud optical thickness (COT) from global solar radiation (GSR) detected by ground-based pyranometer, and approaches to input aerosol/molecular/gas parameters for COT retrievals are presented. On the basis of numerical simulations and comparative tests, main error factors of COT retrievals are analyzed, which include radiation data error, cloud inhomogeneity, uncertainties of aerosol optical parameters, and surface albedo. The retrieved COT error, caused by a -5% or 5% systematic error of the GSR measurement, is within ±0.6 and ±5.0 for COT ranges of 0-5.0 and 5-100, respectively. The AOT, the aerosol single scatter albedo (SSA), and the surface albedo are three significant parameters affecting COT retrieval accuracy. The mean SSA in the pyranometer spectral response range and the broadband surface albedo are suitably used in the retrievals. If uncertainties of AOT, SSA, and surface albedo are within ±0.1, ±0.05, and ±0.05, respectively, the retrieval accuracy is accepted for most applications. Furthermore, COTs (?Pyr) from pyranometer data at two meteorological observatories are compared with COTs (?ISCCP) from ISCCP and COTs (?MODIS) from MODIS. The relative standard deviations between monthly mean ?Pyr and ?MODIS, or ?Pyr and ?ISCCP, are all less than 45.4% for both sites. The agreement among the yearly mean ?Pyr,?MODIS, and ?ISCCP is satisfactory. The absolute (relative) deviations between the yearly mean ?Pyr and ?MODIS are within ±1.55 (8%) for both sites, and the deviations between the ?Pyr and ?ISCCP are within ±1.94 (25%). The yearly mean ?Pyr also agrees considerably well with ?ISCCP in the broken cloud case.

Qiu, Jinhuan

2006-11-01

233

Study of Cloud Computing Security Based on Private Face Recognition  

Microsoft Academic Search

Supporting study of a method to solve cloud computing security issue with private face recognition. The method has three parts: user part provides face images; cloud initialization part has a face subspace and templates database; cloud private matching identification part contains the core algorithm of the method, comparing two encrypted numbers under double-encrypted conditions. The experimental results show the method

Chenguang Wang; Huaizhi Yan

2010-01-01

234

Creating a Cloud-based Life Science Gateway  

Microsoft Academic Search

Cloud computing is increasingly becoming a popular solution to massive data analysis in life science community. To completely harness the power of Cloud computing, scientists need science gateways to efficiently manage their virtual machines, share Cloud resources, and run high-throughput sequence analysis with bioinformatics software tools. This paper introduces the development and use of Open Life Science Gateway, which manages

Wenjun Wu; Hui Zhang; ZhenAn Li; Yaokuan Mao

2011-01-01

235

LT Codes-based Secure and Reliable Cloud Storage Service  

E-print Network

and State University, VA, USA Abstract--With the increasing adoption of cloud computing for data storage The many advantages of cloud computing are increasingly attracting individuals and organizations to move is becoming a pervasive service. Along with the widespread enthusiasm on cloud comput- ing, however, concerns

Hou, Y. Thomas

236

Cloud-Based Design and Manufacturing: Status and Promise  

E-print Network

Schaefer Abstract The information technology industry has benefited considerably from cloud computing by globalization, cloud computing is one of the major advances in the field of computing. In recent years, the information tech- nology (IT) sector has significantly benefited from cloud computing through (1) on

237

A High Resolution Hydrometer Phase Classifier Based on Analysis of Cloud Radar Doppler Spectra.  

SciTech Connect

The lifecycle and radiative properties of clouds are highly sensitive to the phase of their hydrometeors (i.e., liquid or ice). Knowledge of cloud phase is essential for specifying the optical properties of clouds, or else, large errors can be introduced in the calculation of the cloud radiative fluxes. Current parameterizations of cloud water partition in liquid and ice based on temperature are characterized by large uncertainty (Curry et al., 1996; Hobbs and Rangno, 1998; Intriery et al., 2002). This is particularly important in high geographical latitudes and temperature ranges where both liquid droplets and ice crystal phases can exist (mixed-phase cloud). The mixture of phases has a large effect on cloud radiative properties, and the parameterization of mixed-phase clouds has a large impact on climate simulations (e.g., Gregory and Morris, 1996). Furthermore, the presence of both ice and liquid affects the macroscopic properties of clouds, including their propensity to precipitate. Despite their importance, mixed-phase clouds are severely understudied compared to the arguably simpler single-phase clouds. In-situ measurements in mixed-phase clouds are hindered due to aircraft icing, difficulties distinguishing hydrometeor phase, and discrepancies in methods for deriving physical quantities (Wendisch et al. 1996, Lawson et al. 2001). Satellite-based retrievals of cloud phase in high latitudes are often hindered by the highly reflecting ice-covered ground and persistent temperature inversions. From the ground, the retrieval of mixed-phase cloud properties has been the subject of extensive research over the past 20 years using polarization lidars (e.g., Sassen et al. 1990), dual radar wavelengths (e.g., Gosset and Sauvageot 1992; Sekelsky and McIntosh, 1996), and recently radar Doppler spectra (Shupe et al. 2004). Millimeter-wavelength radars have substantially improved our ability to observe non-precipitating clouds (Kollias et al., 2007) due to their excellent sensitivity that enables the detection of thin cloud layers and their ability to penetrate several non-precipitating cloud layers. However, in mixed-phase clouds conditions, the observed Doppler moments are dominated by the highly reflecting ice crystals and thus can not be used to identify the cloud phase. This limits our ability to identify the spatial distribution of cloud phase and our ability to identify the conditions under which mixed-phase clouds form.

Luke,E.; Kollias, P.

2007-08-06

238

The Open Cloud Testbed: Supporting Open Source Cloud Computing Systems Based on Large Scale High Performance, Dynamic Network Services  

NASA Astrophysics Data System (ADS)

Recently, a number of cloud platforms and services have been developed for data intensive computing, including Hadoop, Sector, CloudStore (formerly KFS), HBase, and Thrift. In order to benchmark the performance of these systems, to investigate their interoperability, and to experiment with new services based on flexible compute node and network provisioning capabilities, we have designed and implemented a large scale testbed called the Open Cloud Testbed (OCT). Currently OCT has 120 nodes in 4 data centers: Baltimore, Chicago (two locations), and San Diego. In contrast to other cloud testbeds, which are in small geographic areas and which are based on commodity Internet services, the OCT is a wide area testbed and the 4 data centers are connected with a high performance 10Gb/s network, based on a foundation of dedicated lightpaths. This testbed can address the requirements of extremely large data streams that challenge other types of distributed infrastructure. We have also developed several utilities to support the development of cloud computing systems and services, including novel node and network provisioning services, a monitoring system, and an RPC system. In this paper, we describe the OCT concepts, architecture, infrastructure, a few benchmarks that were developed for this platform, interoperability studies, and results.

Grossman, Robert; Gu, Yunhong; Sabala, Michal; Bennet, Colin; Seidman, Jonathan; Mambratti, Joe

239

Simulation Platform: a cloud-based online simulation environment.  

PubMed

For multi-scale and multi-modal neural modeling, it is needed to handle multiple neural models described at different levels seamlessly. Database technology will become more important for these studies, specifically for downloading and handling the neural models seamlessly and effortlessly. To date, conventional neuroinformatics databases have solely been designed to archive model files, but the databases should provide a chance for users to validate the models before downloading them. In this paper, we report our on-going project to develop a cloud-based web service for online simulation called "Simulation Platform". Simulation Platform is a cloud of virtual machines running GNU/Linux. On a virtual machine, various software including developer tools such as compilers and libraries, popular neural simulators such as GENESIS, NEURON and NEST, and scientific software such as Gnuplot, R and Octave, are pre-installed. When a user posts a request, a virtual machine is assigned to the user, and the simulation starts on that machine. The user remotely accesses to the machine through a web browser and carries out the simulation, without the need to install any software but a web browser on the user's own computer. Therefore, Simulation Platform is expected to eliminate impediments to handle multiple neural models that require multiple software. PMID:21741207

Yamazaki, Tadashi; Ikeno, Hidetoshi; Okumura, Yoshihiro; Satoh, Shunji; Kamiyama, Yoshimi; Hirata, Yutaka; Inagaki, Keiichiro; Ishihara, Akito; Kannon, Takayuki; Usui, Shiro

2011-09-01

240

Reference values for height and weight in Prader-Willi syndrome based on 315 patients  

Microsoft Academic Search

The spontaneous growth of 315 patients (109 girls and 208 boys) with Prader-Willi syndrome (PWS) was analysed in a mixed\\u000a longitudinal and cross-sectional manner. 33 patients were seen in the department between 1970 and 1994; height and weight\\u000a of 76 patients from Germany were evaluated by means of a questionnaire with detailed measuring instructions, and 206 definite\\u000a cases were added

H. A. Wollmann; U. Schultz; M. L. Grauer; M. B. Ranke

1998-01-01

241

Interferometry for Ellipso-Height-Topometry - Part 1: Coherence scanning on the base of spacial coherence  

NASA Astrophysics Data System (ADS)

A modified Linnik and a Mirau interferometer are introduced which can be used for Ellipso-Height-Topometry. With these, a set of topographies can be measured, where the measured height H(x, y), the ellipsometric angles [Phi](x, y), [Delta](x, y) and the degree of polarization P(x, y) all refer to the same pixels of the raster. This coherent set of topographies can be used to calculate topographies of further quantities, e. g. the complex refractive index N(x, y) = n(x, y) - k(x, y) i of bulk surfaces or parameters of thin films, even for discontinuous structures. Material maps which indicate the presence of specific materials and show their exact location in the frame can be generated. In part I, these interferometric configurations are described and results are presented. It is shown that for oblique incidence, which is obligatory for an ellipsometric detection, the envelope of the interferogram or correlogram can be narrowed for improved z-scan (vertical) discrimination, even in the case of the height detection. By a theoretical analysis, we prove that this is an effect of conventional spatial coherence as a function of the width of the source and can be utilized without any source modulation or source shaping even for small spectral bandwidth of the radiation. This is verified for tungsten incandescent lamps, and for LED's. In part II algorithms for ellipsometric measurements, calibration procedures and first complete topography sets are presented.

Leonhardt, K.; Droste, U.; Tiziani, H. J.

242

The impact of frenulum height on strains in maxillary denture bases  

PubMed Central

PURPOSE The midline fracture of maxillary complete dentures is a frequently encountered complication. The purpose of this study was to assess the effect of frenulum height on midline strains of maxillary complete dentures. MATERIALS AND METHODS A removable maxillary complete denture was fabricated and duplicated seven times. Four different labial frenulum heights were tested for stresses occurring on the palatal cameo surface. The strains were measured with strain gauges placed on 5 different locations and the stresses were calculated. To mimic occlusal forces bilaterally 100 N of load was applied from the premolar and molar region. RESULTS A statistically significant association between the height of the labial frenulum and the calculated stresses and strains was shown (P<.05) predominantly on the midline and especially on the incisive papilla. The results showed that stress on the anterior midline of the maxillary complete denture increases with a higher labial frenulum. CONCLUSION Within the limitations of this in vitro study, it can be concluded that the stress on the anterior midline of the maxillary complete denture increases with a higher labial frenulum. Surgical or mechanical precautions should be taken to prevent short-term failure of maxillary complete dentures due to stress concentration and low cycle fatigue tendency at the labial frenulum region. PMID:24353878

Bilhan, Hakan; Baysal, Gokhan; Sunbuloglu, Emin; Bozdag, Ergun

2013-01-01

243

Cloud based intelligent system for delivering health care as a service.  

PubMed

The promising potential of cloud computing and its convergence with technologies such as mobile computing, wireless networks, sensor technologies allows for creation and delivery of newer type of cloud services. In this paper, we advocate the use of cloud computing for the creation and management of cloud based health care services. As a representative case study, we design a Cloud Based Intelligent Health Care Service (CBIHCS) that performs real time monitoring of user health data for diagnosis of chronic illness such as diabetes. Advance body sensor components are utilized to gather user specific health data and store in cloud based storage repositories for subsequent analysis and classification. In addition, infrastructure level mechanisms are proposed to provide dynamic resource elasticity for CBIHCS. Experimental results demonstrate that classification accuracy of 92.59% is achieved with our prototype system and the predicted patterns of CPU usage offer better opportunities for adaptive resource elasticity. PMID:24139021

Kaur, Pankaj Deep; Chana, Inderveer

2014-01-01

244

An Automated Cloud Mask Algorithm for the Micropulse Lidar  

Microsoft Academic Search

To perform cloud base analysis, an automated technique fo r sky signal using the standard lidar equation (Spinhirn e determination of cloud base height from the raw lidar return s 1993) and midlatitude standard atmospheres. Afte r is needed. Previously, a straightforwar d signal thresholdin g normalization, the observations form a swarm of points about algorithm was used to determine

G. G. Mace

245

Analysis of the Security and Privacy Requirements of Cloud-Based Electronic Health Records Systems  

PubMed Central

Background The Cloud Computing paradigm offers eHealth systems the opportunity to enhance the features and functionality that they offer. However, moving patients’ medical information to the Cloud implies several risks in terms of the security and privacy of sensitive health records. In this paper, the risks of hosting Electronic Health Records (EHRs) on the servers of third-party Cloud service providers are reviewed. To protect the confidentiality of patient information and facilitate the process, some suggestions for health care providers are made. Moreover, security issues that Cloud service providers should address in their platforms are considered. Objective To show that, before moving patient health records to the Cloud, security and privacy concerns must be considered by both health care providers and Cloud service providers. Security requirements of a generic Cloud service provider are analyzed. Methods To study the latest in Cloud-based computing solutions, bibliographic material was obtained mainly from Medline sources. Furthermore, direct contact was made with several Cloud service providers. Results Some of the security issues that should be considered by both Cloud service providers and their health care customers are role-based access, network security mechanisms, data encryption, digital signatures, and access monitoring. Furthermore, to guarantee the safety of the information and comply with privacy policies, the Cloud service provider must be compliant with various certifications and third-party requirements, such as SAS70 Type II, PCI DSS Level 1, ISO 27001, and the US Federal Information Security Management Act (FISMA). Conclusions Storing sensitive information such as EHRs in the Cloud means that precautions must be taken to ensure the safety and confidentiality of the data. A relationship built on trust with the Cloud service provider is essential to ensure a transparent process. Cloud service providers must make certain that all security mechanisms are in place to avoid unauthorized access and data breaches. Patients must be kept informed about how their data are being managed. PMID:23965254

Fernández, Gonzalo; López-Coronado, Miguel

2013-01-01

246

CloudAnalyst: A CloudSim-Based Visual Modeller for Analysing Cloud Computing Environments and Applications  

Microsoft Academic Search

Abstract—Advances in Cloud computing opens up many new possibilities for Internet applications developers. Previously, a main,concern of Internet applications developers was deployment and hosting of applications, because it required acquisition of a server with a fixed capacity able to handle the expected application peak demand and the installation and maintenance of the whole software infrastructure of the platform supporting the

Bhathiya Wickremasinghe; Rodrigo N. Calheiros; Rajkumar Buyya

2010-01-01

247

Remote Sensing of Cloud Properties using Ground-based Measurements of Zenith Radiance  

NASA Technical Reports Server (NTRS)

An extensive verification of cloud property retrievals has been conducted for two algorithms using zenith radiances measured by the Atmospheric Radiation Measurement (ARM) Program ground-based passive two-channel (673 and 870 nm) Narrow Field-Of-View Radiometer. The underlying principle of these algorithms is that clouds have nearly identical optical properties at these wavelengths, but corresponding spectral surface reflectances (for vegetated surfaces) differ significantly. The first algorithm, the RED vs. NIR, works for a fully three-dimensional cloud situation. It retrieves not only cloud optical depth, but also an effective radiative cloud fraction. Importantly, due to one-second time resolution of radiance measurements, we are able, for the first time, to capture detailed changes in cloud structure at the natural time scale of cloud evolution. The cloud optical depths tau retrieved by this algorithm are comparable to those inferred from both downward fluxes in overcast situations and microwave brightness temperatures for broken clouds. Moreover, it can retrieve tau for thin patchy clouds, where flux and microwave observations fail to detect them. The second algorithm, referred to as COUPLED, couples zenith radiances with simultaneous fluxes to infer 2. In general, the COUPLED and RED vs. NIR algorithms retrieve consistent values of tau. However, the COUPLED algorithm is more sensitive to the accuracies of measured radiance, flux, and surface reflectance than the RED vs. NIR algorithm. This is especially true for thick overcast clouds where it may substantially overestimate z.

Chiu, J. Christine; Marshak, Alexander; Knyazikhin, Yuri; Wiscombe, Warren J.; Barker, Howard W.; Barnard, James C.; Luo, Yi

2006-01-01

248

Reduction of solar UV by clouds: A comparison between satellite-derived cloud effects and ground-based radiation measurements  

NASA Astrophysics Data System (ADS)

Assessment of the effects of ozone depletion on biologically effective solar UV at ground level has been greatly advanced through the use of remote sensing data. Satellite data on atmospheric properties allow the construction of geographically distributed surface UV radiation maps based on radiative transfer calculations. In this respect, clouds play a dominant but rather complex role. We compared the reduction of daily UV doses due to clouds, as derived from satellite cloud data, with the reduction derived from routine ground-based measurements of global solar radiation (i.e., broadband total solar irradiances with wavelengths between 0.3 and 2.8 ?m). An empirical relationship is used to link the reduction due to clouds of global solar radiation and UV radiation. The abundance of global solar radiation measurements (data from over 125 stations in 30 satellite grid cells) for the European region ensured a sound basis for the data analysis for the period considered (May, June, and July of 1990, 1991, and 1992). Approximately 6500 daily UV-reduction factors, defined as the ratio of daily UV doses calculated with and without clouds, were thus obtained applying both methods. The daily UV-reduction factors (and 10-day averaged UV reduction factors) from the two independent sources correlated well, with r2=0.83 (r2=0.89), and had a standard deviation of 0.06 (0.03). Over 90% of the satellite-derived results agreed within a range of +/-0.14 (+/-0.07) with the ground-based measurement-derived results. We evaluated sources of uncertainty related to spatial and temporal resolution, and optical properties, and estimated their consequences n and range. Among these different sources the largest uncertainties are caused by the sampling error, i.e., grid-cell average versus station average, which is on average 0.10 for daily UV-reduction factors. Information on the atmospheric optical properties during the measurements may reduce the stated range of uncertainty from +/-0.14 to +/-0.07. The variation of the measurements from station to station is then the limiting factor. We concluded that the reduction of daily UV based on satellite-derived cloud cover and cloud optical thickness relates well with the UV reduction due to clouds derived from ground-based global solar radiation measurements.

Matthijsen, J.; Slaper, H.; Reinen, H. A. J. M.; Velders, G. J. M.

249

Combined satellite and radar retrievals of drop concentration and CCN at convective cloud base  

NASA Astrophysics Data System (ADS)

number of activated cloud condensation nuclei (CCN) into cloud drops at the base of convective clouds (Na) is retrieved based on the high-resolution (375 m) satellite retrievals of vertical profiles of convective cloud drop effective radius (re). The maximum cloud base supersaturation (S) is calculated when Na is combined with radar-measured updraft and yields CCN(S), which was validated well against ground-based CCN measurements during the conditions of well-mixed boundary layer over the U.S. Department of Energy's Atmospheric System Research Southern Great Plains site. Satellite retrieving Na is a new capability, which is one essential component of simultaneous measurements of cloud microstructure and CCN from space by using clouds as natural CCN chambers. This has to be complemented by a methodology for satellite estimates of cloud base updraft, which is yet to be developed and demonstrated. In the mean time, the retrieved Na can be used for the assimilation of the combined CCN and updraft effects on clouds in models.

Rosenfeld, Daniel; Fischman, Baruch; Zheng, Youtong; Goren, Tom; Giguzin, David

2014-05-01

250

Cloud model-based simulation of spaceborne radar observations  

NASA Technical Reports Server (NTRS)

Simulations of observations from potential spaceborne radars are made based on storm structure generated from the three-dimensional (3D) Goddard cumulus ensemble model simulation of an intense overland convective system. Five frequencies of 3, 10, 14, 35, and 95 GHz are discussed, but the Tropical Rainfall Measuring Mission precipitation radar sensor frequency (14 GHz) is the focus of this study. Radar reflectives and their attenuation in various atmospheric conditions are studied in this simulation. With the attenuation from cloud and precipitation in the estimation of reflectivity factor (dBZ), the reflectivities in the lower atmosphere in the convective cores are significantly reduced. With spatial resolution of 4 km X 4 km, attenuation at 14 GHz may cause as large as a 20-dBZ difference between the simulated measurements of the peak, Z(sub mp) and near-surface reflectivity, Z(sub ms) in the most intense convective region. The Z(sub mp) occurs at various altitudes depending on the hydrometeor concentrations and their vertical distribution. Despite the significant attenuation in the intense cores, the presence of the rain maximum is easily detected by using information of Z(sub mp). In the stratiform region, the attenuation is quite limited (usually less than 5 dBZ), and the reduction of reflectivity is mostly related to the actual vertical structure of cloud distribution. Since Z(sub ms) suffers severe attenuation and tends to underestimate surface rainfall intensity in convective regions. Z(sub mp) can be more representative for rainfall retrieval in the lower atmosphere in these regions. In the stratiform region where attenuation is negligible, however, Z(sub mp) tends to overestimate surface rainfall and Z(sub ms) is more appropriate for rainfall retrieval. A hybrid technique using a weight between the two rain intensities is tested and found potentially usefull for future applications. The estimated surface rain-rate map based on this hybrid approach captures many of the details of the cloud model rain field but still slightly underestimates the rain-rate maximum.

Yeh, H.-Y. M.; Prasad, N.; Meneghini, R.; Tao, W.-K.; Jones, J. A.; Adler, R. F.

1995-01-01

251

Cloud based toolbox for image analysis, processing and reconstruction tasks.  

PubMed

This chapter describes a novel way of carrying out image analysis, reconstruction and processing tasks using cloud based service provided on the Australian National eResearch Collaboration Tools and Resources (NeCTAR) infrastructure. The toolbox allows users free access to a wide range of useful blocks of functionalities (imaging functions) that can be connected together in workflows allowing creation of even more complex algorithms that can be re-run on different data sets, shared with others or additionally adjusted. The functions given are in the area of cellular imaging, advanced X-ray image analysis, computed tomography and 3D medical imaging and visualisation. The service is currently available on the website www.cloudimaging.net.au . PMID:25381109

Bednarz, Tomasz; Wang, Dadong; Arzhaeva, Yulia; Lagerstrom, Ryan; Vallotton, Pascal; Burdett, Neil; Khassapov, Alex; Szul, Piotr; Chen, Shiping; Sun, Changming; Domanski, Luke; Thompson, Darren; Gureyev, Timur; Taylor, John A

2015-01-01

252

CloudWF: A Computational Workflow System for Clouds Based on Hadoop  

NASA Astrophysics Data System (ADS)

This paper describes CloudWF, a scalable and lightweight computational workflow system for clouds on top of Hadoop. CloudWF can run workflow jobs composed of multiple Hadoop MapReduce or legacy programs. Its novelty lies in several aspects: a simple workflow description language that encodes workflow blocks and block-to-block dependencies separately as standalone executable components; a new workflow storage method that uses Hadoop HBase sparse tables to store workflow information internally and reconstruct workflow block dependencies implicitly for efficient workflow execution; transparent file staging with Hadoop DFS; and decentralized workflow execution management relying on the MapReduce framework for task scheduling and fault tolerance. This paper describes the design and implementation of CloudWF.

Zhang, Chen; de Sterck, Hans

253

An improved approach for flow-based cloud point extraction.  

PubMed

Novel strategies are proposed to circumvent the main drawbacks of flow-based cloud point extraction (CPE). The surfactant-rich phase (SRP) was directly retained into the optical path of the spectrophotometric cell, thus avoiding its dilution previously to the measurement and yielding higher sensitivity. Solenoid micro-pumps were exploited to improve mixing by the pulsed flow and also to modulate the flow-rate for retention and removal of the SRP, thus avoiding the elution step, often carried out with organic solvents. The heat released and the increase of the salt concentration provided by an on-line neutralization reaction were exploited to induce the cloud point without an external heating device. These innovations were demonstrated by the spectrophotometric determination of iron, yielding a linear response from 10 to 200 ?g L(-1) with a coefficient of variation of 2.3% (n=7). Detection limit and sampling rate were estimated at 5 ?g L(-1) (95% confidence level) and 26 samples per hour, respectively. The enrichment factor was 8.9 and the procedure consumed only 6 ?g of TAN and 390 ?g of Triton X-114 per determination. At the 95% confidence level, the results obtained for freshwater samples agreed with the reference procedure and those obtained for digests of bovine muscle, rice flour, brown bread and tort lobster agreed with the certified reference values. The proposed procedure thus shows advantages in relation to previously proposed approaches for flow-based CPE, being a fast and environmental friendly alternative for on-line separation and pre-concentration. PMID:24745739

Frizzarin, Rejane M; Rocha, Fábio R P

2014-04-11

254

A new cloud and aerosol layer detection method based on micropulse lidar measurements  

E-print Network

) [Clothiaux et al., 1995], or from temperature and water vapor profiles [Zhang et al., 2013]. The micropulseA new cloud and aerosol layer detection method based on micropulse lidar measurements Chuanfeng algorithm to detect aerosols and clouds based on micropulse lidar measurements. A semidiscretization

Li, Zhanqing

255

Retrieval of atmospheric attenuation using combined ground-based and airborne 95-GHz cloud radar measurements  

NASA Technical Reports Server (NTRS)

This paper discusses cloud radar calibration and intercomparison of airborne and ground-based radar measurements and presents a unique algorithm for attenuation retrieval. This algorithm is based on dual 95-GHz radar measurements of the same cloud and precipitation volumes collected from opposing viewing angles.

Li, L.; Sekelsky, S.; Reising, S.; Swift, C.; Durden, S.; Sadowy, G.; Dinardo, S.; Li, F.; Huffman, A.; Stephens, G.; Babb, D.; Rosenberger, H.

2001-01-01

256

Examination of the quality of GOSAT/CAI cloud flag data over Beijing using ground-based cloud data  

NASA Astrophysics Data System (ADS)

It has been several years since the Greenhouse Gases Observing Satellite (GOSAT) began to observe the distribution of CO2 and CH4 over the globe from space. Results from Thermal and Near-infrared Sensor for Carbon Observation-Cloud and Aerosol Imager (TANSO-CAI) cloud screening are necessary for the retrieval of CO2 and CH4 gas concentrations for GOSAT TANSO-Fourier Transform Spectrometer (FTS) observations. In this study, TANSO-CAI cloud flag data were compared with ground-based cloud data collected by an all-sky imager (ASI) over Beijing from June 2009 to May 2012 to examine the data quality. The results showed that the CAI has an obvious cloudy tendency bias over Beijing, especially in winter. The main reason might be that heavy aerosols in the sky are incorrectly determined as cloudy pixels by the CAI algorithm. Results also showed that the CAI algorithm sometimes neglects some high thin cirrus cloud over this area.

Huo, Juan; Zhang, Wenxing; Zeng, Xiaoxia; Lü, Daren; Liu, Yi

2013-11-01

257

Surface height retrieval based on fringe shifting of color-encoded structured light pattern.  

PubMed

A new method of fringe shifting for color structured pattern projection is presented for three-dimensional (3D) surface height measurement. Temporal encoding of color stripes is combined with locally spatial shifting of multiple fringes to realize image acquisition with a small number of pattern projections. Object topography is retrieved with high resolution by decoding the code word of each fringe with the help of the redundant information provided by the shifting patterns and the encoding patterns in their temporal and spatial neighborhoods. An application to evaluate the shape of a buckled tube demonstrates the effectiveness of the method. PMID:18709092

Chen, Hui Jun; Zhang, Jue; Fang, Jing

2008-08-15

258

Method for validating cloud mask obtained from satellite measurements using ground-based sky camera.  

PubMed

Error propagation in Earth's atmospheric, oceanic, and land surface parameters of the satellite products caused by misclassification of the cloud mask is a critical issue for improving the accuracy of satellite products. Thus, characterizing the accuracy of the cloud mask is important for investigating the influence of the cloud mask on satellite products. In this study, we proposed a method for validating multiwavelength satellite data derived cloud masks using ground-based sky camera (GSC) data. First, a cloud cover algorithm for GSC data has been developed using sky index and bright index. Then, Moderate Resolution Imaging Spectroradiometer (MODIS) satellite data derived cloud masks by two cloud-screening algorithms (i.e., MOD35 and CLAUDIA) were validated using the GSC cloud mask. The results indicate that MOD35 is likely to classify ambiguous pixels as "cloudy," whereas CLAUDIA is likely to classify them as "clear." Furthermore, the influence of error propagations caused by misclassification of the MOD35 and CLAUDIA cloud masks on MODIS derived reflectance, brightness temperature, and normalized difference vegetation index (NDVI) in clear and cloudy pixels was investigated using sky camera data. It shows that the influence of the error propagation by the MOD35 cloud mask on the MODIS derived monthly mean reflectance, brightness temperature, and NDVI for clear pixels is significantly smaller than for the CLAUDIA cloud mask; the influence of the error propagation by the CLAUDIA cloud mask on MODIS derived monthly mean cloud products for cloudy pixels is significantly smaller than that by the MOD35 cloud mask. PMID:25402920

Letu, Husi; Nagao, Takashi M; Nakajima, Takashi Y; Matsumae, Yoshiaki

2014-11-01

259

An Approach for Improving Cirrus Cloud-Top Pressure/Height Estimation by Merging High-Spatial-Resolution Infrared-Window Imager Data with  

E-print Network

, but it lacks IR spectral bands that are sensitive to absorption by carbon dioxide (CO2) or water vapor (H2O of temperature, water vapor, and ozone and total column estimates of other trace gas species). Corresponding resolution. Comparisons with Cloud­Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO

Baum, Bryan A.

260

Cloud droplet size distributions in low-level stratiform clouds  

SciTech Connect

A database of stratus cloud droplet size distribution parameters, derived from in situ data reported in the existing literature, was created, facilitating intercomparison among datasets and quantifying typical values and their variability. From the datasets, which were divided into marine and continental groups, several parameters are presented, including the total number concentration, effective diameter, mean diameter, standard deviation of the droplet diameters about the mean diameter, and liquid water content, as well as the parameters of modified gamma and lognormal distributions. In light of these results, the appropriateness of common assumptions used in remote sensing of cloud droplet size distributions is discussed. For example, vertical profiles of mean diameter, effective diameter, and liquid water content agreed qualitatively with expectations based on the current paradigm of cloud formation. Whereas parcel theory predicts that the standard deviation about the mean diameter should decrease with height, the results illustrated that the standard deviation generally increases with height. A feature common to all marine clouds was their approximately constant total number concentration profiles; however, the total number concentration profiles of continental clouds were highly variable. Without cloud condensation nuclei spectra, classification of clouds into marine and continental groups is based on indirect methods. After reclassification of four sets of measurements in the database, there was a fairly clear dichotomy between marine and continental clouds, but a great deal of variability within each classification. The relevant applications of this study lie in radiative transfer and climate issues, rather than in cloud formation and dynamics. Techniques that invert remotely sensed measurements into cloud droplet size distributions frequently rely on a priori assumptions, such as constant number concentration profiles and constant spectral width. The results of this paper provide a basis for evaluating the sensitivity of these techniques. In particular, there were large enough differences in observed droplet spectral widths to significantly affect remotely sensed determinations of cloud microphysics.

Miles, N.L.; Verlinde, J.; Clothiaux, E.E.

2000-01-15

261

Cloud-based large-scale air traffic flow optimization  

NASA Astrophysics Data System (ADS)

The ever-increasing traffic demand makes the efficient use of airspace an imperative mission, and this paper presents an effort in response to this call. Firstly, a new aggregate model, called Link Transmission Model (LTM), is proposed, which models the nationwide traffic as a network of flight routes identified by origin-destination pairs. The traversal time of a flight route is assumed to be the mode of distribution of historical flight records, and the mode is estimated by using Kernel Density Estimation. As this simplification abstracts away physical trajectory details, the complexity of modeling is drastically decreased, resulting in efficient traffic forecasting. The predicative capability of LTM is validated against recorded traffic data. Secondly, a nationwide traffic flow optimization problem with airport and en route capacity constraints is formulated based on LTM. The optimization problem aims at alleviating traffic congestions with minimal global delays. This problem is intractable due to millions of variables. A dual decomposition method is applied to decompose the large-scale problem such that the subproblems are solvable. However, the whole problem is still computational expensive to solve since each subproblem is an smaller integer programming problem that pursues integer solutions. Solving an integer programing problem is known to be far more time-consuming than solving its linear relaxation. In addition, sequential execution on a standalone computer leads to linear runtime increase when the problem size increases. To address the computational efficiency problem, a parallel computing framework is designed which accommodates concurrent executions via multithreading programming. The multithreaded version is compared with its monolithic version to show decreased runtime. Finally, an open-source cloud computing framework, Hadoop MapReduce, is employed for better scalability and reliability. This framework is an "off-the-shelf" parallel computing model that can be used for both offline historical traffic data analysis and online traffic flow optimization. It provides an efficient and robust platform for easy deployment and implementation. A small cloud consisting of five workstations was configured and used to demonstrate the advantages of cloud computing in dealing with large-scale parallelizable traffic problems.

Cao, Yi

262

Height estimates using AATSR dual view  

NASA Astrophysics Data System (ADS)

We describe a height estimate algorithm based on radiances measured at the top of the atmosphere (TOA) by the Advanced Along Track Scanning Radiometer (AATSR) aboard the ENVISAT satellite. The algorithm is designed to estimate volcanic ash plume top heights, but it can be used for other high contrast features as well, such as dust and smoke plumes, meteorological clouds or surface features. The algorithm is designed to be fully automatic, which allows it to be run in parallel with various retrieval algorithms used in Helsinki, such as aerosol and cloud optical depth retrievals and ash plume concentration retrievals. Information on the feature height is important for choosing the correct retrieval parameters, and could be used for example in dispersion calculations. The center wavelengths of the AATSR visible (VIS) and near-infrared (NIR) channels are 0.555, 0.659, 0.865, 1.61 ?m. The AATSR thermal channels are centered at 3.7, 11, and 12 ?m and provide brightness temperature data. The visible channels can be used for aerosol optical depth (AOD) retrievals, while the thermal channels are useful in ash or dust detection. The AATSR instrument has two views, a nadir view and a 55° forward view. The stereo view is used to estimate the feature height. A spatial correlation algorithm can be used to collocate the views, and the resulting parallax gives a height estimate with nominal accuracy of 1 km. Statistical methods are used to assess the quality of retrieved heights and to filter out unreliable data. The stereo view is also used in the AOD retrieval, with the AATSR dual view (ADV) algorithm, which does not require a priori knowledge of the surface reflectance.

Virtanen, Timo; Kolmonen, Pekka; Sogacheva, Larisa; Sundström, Anu-Maija; Rodriguez, Edith; Atlaskina, Ksenia; Hannukainen, Meri; Saponaro, Giulia; de Leeuw, Gerrit

2013-04-01

263

Analysis of cloud-based solutions on EHRs systems in different scenarios.  

PubMed

Nowadays with the growing of the wireless connections people can access all the resources hosted in the Cloud almost everywhere. In this context, organisms can take advantage of this fact, in terms of e-Health, deploying Cloud-based solutions on e-Health services. In this paper two Cloud-based solutions for different scenarios of Electronic Health Records (EHRs) management system are proposed. We have researched articles published between the years 2005 and 2011 about the implementation of e-Health services based on the Cloud in Medline. In order to analyze the best scenario for the deployment of Cloud Computing two solutions for a large Hospital and a network of Primary Care Health centers have been studied. Economic estimation of the cost of the implementation for both scenarios has been done via the Amazon calculator tool. As a result of this analysis two solutions are suggested depending on the scenario: To deploy a Cloud solution for a large Hospital a typical Cloud solution in which are hired just the needed services has been assumed. On the other hand to work with several Primary Care Centers it's suggested the implementation of a network, which interconnects these centers with just one Cloud environment. Finally it's considered the fact of deploying a hybrid solution: in which EHRs with images will be hosted in the Hospital or Primary Care Centers and the rest of them will be migrated to the Cloud. PMID:22492177

Fernández-Cardeñosa, Gonzalo; de la Torre-Díez, Isabel; López-Coronado, Miguel; Rodrigues, Joel J P C

2012-12-01

264

Wuthering Heights  

Microsoft Academic Search

Wuthering Heights tells the story of a romance between two youngsters: Catherine Earnshaw and an orphan boy, Heathcliff. After she rejects him for a boy from a better background he develops a lust for revenge that takes over his life. In attempting to win her back and destroy those he blames for his loss Heathcliff creates a living hell for

Emily Bronte

2005-01-01

265

Sharing-based Privacy and Availability of Cloud Data Warehouses  

E-print Network

-growing trend in many business (e.g., finance, telecoms, insurance, logistics...) and non-business (e" offerings by both cloud start-ups and major BI industry vendors, with high economic stakes. Moreover, the elasticity characteristic of cloud computing, i.e., the dynamic on-demand provisioning of resources, does

Paris-Sud XI, Université de

266

Study and Application on Cloud Covered Rate for Agroclimatical Distribution Using In Guangxi Based on Modis Data  

NASA Astrophysics Data System (ADS)

Based on analyzing of the physical characteristics of cloud and importance of cloud in agricultural production and national economy, cloud is a very important climatic resources such as temperature, precipitation and solar radiation. Cloud plays a very important role in agricultural climate division .This paper analyzes methods of cloud detection based on MODIS data in China and Abroad . The results suggest that Quanjun He method is suitable to detect cloud in Guangxi. State chart of cloud cover in Guangxi is imaged by using Quanjun He method .We find out the approach of calculating cloud covered rate by using the frequency spectrum analysis. At last, the Guangxi is obtained. Taking Rongxian County Guangxi as an example, this article analyze the preliminary application of cloud covered rate in distribution of Rong Shaddock pomelo . Analysis results indicate that cloud covered rate is closely related to quality of Rong Shaddock pomelo.

Yang, Xin; Zhong, Shiquan; Sun, Han; Tan, Zongkun; Li, Zheng; Ding, Meihua

267

Aerosols and cirrus clouds over Hanoi, Vietnam: comparison between satellite products and results derived from ground-based lidar measurements  

NASA Astrophysics Data System (ADS)

In this paper, we present examples of aerosol and Cirrus cloud altitude profiles over Hanoi, Vietnam, measured with the ground LIDAR setup of the Institute of Physics. Comparisons are made to LIDAR data collected by the Calipso satellite of the NASA A-Train during its orbits over the Hanoi area. The height distributions for both surface aerosols and Cirrus clouds derived from ground and satellite observations are generally consistent, with distributions between 2km-3km, and 8km-15km respectively for aerosols and Cirrus clouds. Cirrus cloud locations inferred from an analysis of limb spectral radiances obtained by the SCIAMACHY satellite are also consistent with the LIDAR data.

Dothe, H.; Dinh, Trung van; Bui, Hai van; Gruninger, J. H.

2014-11-01

268

A research of resource provider-oriented pricing mechanism based on game theory in Cloud Bank model  

Microsoft Academic Search

Cloud computing is becoming more and more mature, and an IaaS cloud computing model called Cloud Bank [1, 2, 3, 4, 13], which is based on commercial bank model, has been designed. Cloud Bank model can be partly distinguished from other traditional IaaS providers by the sources of infrastructure resources. Compare with traditional IaaS Clouds whose infrastructure resources are almost

Huixi Li; Hao Li

2011-01-01

269

Research on Mobile Multimedia Broadcasting Service Integration Based on Cloud Computing  

Microsoft Academic Search

Mobile Multimedia Broadcasting (MMB) is a new hotspot of wireless application and Cloud computing is a shared services architecture based method. With the analysis on advantages and disadvantages of characteristics in traditional service modes of MMB, the method of virtual computing and distributed processing of Cloud computing is introduced to promote the integration of MMB industrial chain. The reasonable developing

Li Li; Xiong Li; Sun Youxia; Liu Wen

2010-01-01

270

From Desktop to Cloud: A Primer on Internet-Based Computing for Librarians  

Microsoft Academic Search

In the past several years, cloud-based computing has become a major trend for all levels of computer users. This article examines the reasons surrounding this trend. It focuses in particular on how cloud computing is being used by librarians, scientists, and end users. Data storage and sharing, applications, and product development are examples of the growing number of functions finding

Karen Sorensen; Nancy R. Glassman

2011-01-01

271

The research of Cloud Computing based on service plane over optical networks  

Microsoft Academic Search

The implementation of Cloud Computing over optical networks faces many challenges and opportunities. A cloud computing architecture over optical networks is proposed based on the service plane. And the validity of the architecture we proposed was experimentally demonstrated in our Adaptive Multi-Service Optical Network testbed.

Zhen Li; Dahai Han; Jie Zhang; Xiuzhong Chen; Wanyi Gu; Yuefeng Ji

2009-01-01

272

Efficient similarity search on massive gene data based on cloud computing  

Microsoft Academic Search

As biomedical data grows rapidly nowadays, we are going to study how to efficiently apply cloud computing into biomedical problem. In this paper, the process of solving biomedical problem based on cloud computing is presented. First, the biomedical issue would be focus on the gene match and generation of large amount of the emulated data from real data. Second, a

Zhiqiong Wang; Hao Chen; Yalu Huang; Yu Xu; Longwei Yang; Jingjing Xiao

2011-01-01

273

SamaritanCloud: Secure and Scalable Infrastructure for enabling Location-based Services  

E-print Network

and geographically-dispersed personal computing devices to form a cloud for the purpose of privately sharing relevantSamaritanCloud: Secure and Scalable Infrastructure for enabling Location-based Services Abhishek. However, seeking for such help on existing OSN infrastructures has some disadvantages including loss

Sundaram, Ravi

274

Aircraft Microphysical and Surface-Based Radar Observations of Summertime Arctic Clouds  

E-print Network

Aircraft Microphysical and Surface-Based Radar Observations of Summertime Arctic Clouds R. PAUL Updated analyses of in situ microphysical properties of three Arctic cloud systems sampled by aircraft to the North Pole. Radar­aircraft agreement in reflectivity and derived microphysical parameters was reasonably

Zuidema, Paquita

275

Architecture and Measured Characteristics of a Cloud Based Internet of Things API  

E-print Network

Architecture and Measured Characteristics of a Cloud Based Internet of Things API Geoffrey C. Fox Indiana University, Bloomington IN 47408 USA rdhartma@indiana.edu ABSTRACT The Internet of Things (Io systems [2,3]. This is the vision of the Internet of Things. We present a cloud-compatible open source

276

Raman Lidar Retrievals of Mixed Layer Heights  

NASA Astrophysics Data System (ADS)

Accurate determination of the atmospheric mixing layer (ML) height is important for modeling the transport of aerosols and aerosol precursors and forecasting air quality. Aerosol and water vapor profiles measured by the DOE ARM SGP and the new TWP (Darwin) ground based Raman lidars provide direct measurements of the vertical structure of ML. We have developed automated algorithms to identify sharp gradients in aerosols and water vapor at the top of the ML and have used these algorithms to derive ML heights for extended periods over the last few years. During the afternoon, these ML heights generally compare favorably with ML heights derived from potential temperature profiles derived from coincident radiosondes. However, retrieving ML heights via lidar measurements of water vapor and aerosol gradients is problematic in the presence of elevated aerosol and water vapor layers which are often observed, especially at night. Consequently, we take advantage of recent modifications to these lidars that permit continuous temperature profiling, and compute ML heights using potential temperature profiles derived from Raman lidar and Atmospheric Emitted Radiance Interferometer (AERI) measurements. The resulting ML heights agree well with ML heights derived from radiosondes and provide a more realistic representation of the diurnal ML behavior. We use the Raman lidar aerosol and water vapor profiles and ML heights to derive the fractions of total column precipitable water vapor and aerosol optical thickness within and above the ML and show how the ML heights and these fractions vary with time of day and season. The SGP Raman lidar measurements show that the fraction of the aerosol optical thickness and precipitable water vapor above the ML increases from 30-60% during the day to 60-80% at night. The Darwin Raman lidar measurements reveal a shallow, moist cloud-topped ML with little diurnal variability during the austral summer and deeper ML with more diurnal variability during the austral winter. The Darwin Raman lidar measurements of the diurnal and seasonal variabilities of ML heights and the aerosol and water vapor distributions relative to these ML heights will also be presented.

Ferrare, R. A.; Clayton, M.; Turner, D. D.; Newsom, R. K.; Goldsmith, J.

2012-12-01

277

Temporal changes in bias of body mass index scores based on self-reported height and weight  

PubMed Central

Objectives: To investigate temporal changes in the bias associated with self-reported (as opposed to measured) body mass index (BMI) and explore the relationship of such bias to changing social attitudes towards obesity. Methods: Using data from the National Health and Nutrition Examination Survey covering two time periods, 1988–1994 and 2005–2008, discrepancy scores between self-reported vs measured BMI were generated. Changes in the sensitivity of BMI categories based on self-reports were examined for six weight groups, both for the US adult population as a whole and major demographic groups. Linear regression models were used to examine temporal changes in average bias, as well as attitudes about weight within each weight category and by demographic group. Results: Between 2005–2008 and 1988–1994, the bias towards underestimation of a person's BMI based on interview responses has declined among obese individuals, a trend evident in virtually all demographic subgroups explored. Conversely, most demographic groups showed little change in the extent of bias among underweight and normal-weight individuals. Although the 2005–2008 survey respondents underestimated their measured BMI more than the 1988–1994 respondents, this shift can be entirely explained by the increased prevalence of obesity in more recent years. In fact, obese individuals in 2005–2008 were less likely to overreport their height and underreport their weight than their counterparts in the 1988–1994. Evidence from responses to questions about ideal weight and desire to lose weight point in the direction of a shift in social attitudes, which may make it easier to ‘admit' to greater weight in surveys. Conclusion: Over the past 20 years, the bias in self-reported height and weight has declined leading to more accurate BMI categorizations based on self-report. This change is likely to affect efforts to find correction factors to adjust BMI scores based on self-reported height and weight. PMID:22546777

Stommel, M; Osier, N

2013-01-01

278

Gene-based copy number variation study reveals a microdeletion at 12q24 that influences height in the Korean population.  

PubMed

Height is a classic polygenic trait with high heritability (h(2)=0.8). Recent genome-wide association studies have revealed many independent loci associated with human height. In addition, although many studies have reported an association between copy number variation (CNV) and complex diseases, few have explored the relationship between CNV and height. Recent studies reported that single nucleotide polymorphisms (SNPs) are highly correlated with common CNVs, suggesting that it is warranted to survey CNVs to identify additional genetic factors affecting heritable traits such as height. This study tested the hypothesis that there would be CNV regions (CNVRs) associated with height nearby genes from the GWASs known to affect height. We identified regions containing >1% copy number deletion frequency from 3667 population-based cohort samples using the Illumina HumanOmni1-Quad BeadChip. Among the identified CNVRs, we selected 15 candidate regions that were located within 1Mb of 283 previously reported genes. To assess the effect of these CNVRs on height, statistical analyses were conducted with samples from a case group of 370 taller (upper 10%) individuals and a control group of 1828 individuals (lower 50%). We found that a newly identified 17.7 kb deletion at chromosomal position 12q24.33, approximately 171.6 kb downstream of GPR133, significantly correlated with height; this finding was validated using quantitative PCR. These results suggest that CNVs are potentially important in determining height and may contribute to height variation in human populations. PMID:23147675

Kim, Yun Kyoung; Moon, Sanghoon; Hwang, Mi Yeong; Kim, Dong-Joon; Oh, Ji Hee; Kim, Young Jin; Han, Bok-Ghee; Lee, Jong-Young; Kim, Bong-Jo

2013-02-01

279

Extended field observations of cirrus clouds using a ground-based cloud observing system  

NASA Technical Reports Server (NTRS)

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.

Ackerman, Thomas P.

1994-01-01

280

A new multispectral cloud retrieval method for ship-based solar transmissivity measurements  

NASA Astrophysics Data System (ADS)

Within the German Leibniz-network OCEANET project, ship-based lidar and microwave remote sensing as well as spectral zenith radiance observations with the COmpact RAdiation measurements System (CORAS) were performed. During three cruises latitudes between 50°N and 50°S were covered. A new spectral retrieval method to derive the cloud optical thickness ? and the droplet effective radius reff using CORAS measurements is developed. The method matches CORAS measurements of ratios of spectral transmissivity at six wavelengths with modeled transmissivities. This retrieval is fast and accurate and thus suitable for operational purposes. The new approach circumvents ambiguities of existing cloud retrievals and reduces the influence of measurement uncertainties. It is applied to homogenous and heterogeneous liquid water and cirrus clouds. In boundary layer liquid water clouds, the retrieved effective radius was more variable, whereas in the cirrus it was rather constant. Furthermore, the liquid water path LWP was derived and compared to data from a microwave radiometer. The new retrieval tends to overestimate LWP for thick liquid water clouds but slightly underestimate LWP for thin clouds. The presented method cannot be applied to mixed-phase clouds. The maximum retrieval of ? and reff for liquid water clouds is 80 in ? and 30 ?m in reff, respectively; for cirrus clouds the limitations of the retrieval are 10 in ? and 60 ?m in reff.

Brückner, M.; Pospichal, B.; Macke, A.; Wendisch, M.

2014-10-01

281

Investigation of Low Altitude Water Ice Cloud Formation in Mars using a Laboratory Based Cloud Chamber  

NASA Astrophysics Data System (ADS)

The ice nuclei abilities of the two available Martian regolith analogs (the Mojave Mars simulant and Johnson Space Center Mars-1) to form low altitude water ice clouds in the Martian atmosphere were investigated with the help of the University of Toronto continuous flow diffusion chamber (UT-CFDC). Polydisperse aerosol particles (below 1?m) generated using a dry disperser and monodisperse aerosol particles (100 nm and 240 nm) generated with an atomizer were exposed to different supersaturations with respect to ice as a function of temperature. Experiments using 100 nm size selected sulfuric acid particles defined the homogeneous freezing threshold in the chamber. Both simulants were found to be active ice nuclei in the deposition nucleation mode between 223 K and 203 K. The Mojave Mars simulant particles were found to be slightly better ice nuclei than the Johnson Space Center Mars-1 particles since they require lower supersaturations to nucleate ice at the different tested temperatures. It was observed that the critical supersaturation (Scrit) to activate 1 % of the aerosol particles increased with decreasing temperature. It was also found that Scrit decreased when the particle size was increased from 100 nm to 240 nm. The Johnson Space Center Mars-1 analog behaves similarly to the well known terrestrial ice nuclei such as kaolinite and Arizona test dust particles, whereas, the Mojave Mars simulant behaves closer to another clay, montmorillonite. The m parameter values and the contact angles were calculated from the experimental Scrit. Those values follow the literature trends; however, our values are larger than in previous studies perhaps due to the use of submicron aerosol particles and the lower sensitivity of our system for determining the Scrit values. A general finding is that the barrier to ice nucleation becomes larger at lower temperatures. This behaviour is typically neglected in most of the microphysical models since the nucleation rates at this temperature range are assumed as non temperature dependent. This should be re-evaluated based in the literature data and present results.

Ladino Moreno, L. A.; Abbatt, J.

2012-12-01

282

Measuring effective leaf area index, foliage profile, and stand height in New England forest stands using a full-waveform ground-based lidar  

E-print Network

Measuring effective leaf area index, foliage profile, and stand height in New England forest stands leaf area index (LAI) retrievals from a scanning, ground-based, near-infrared (1064 nm) lidar). The LAI values also matched published values well. Foliage profiles (leaf area with height) retrieved from

Ni-Meister, Wenge

283

Aneka: A Software Platform for .NET-based Cloud Computing  

Microsoft Academic Search

Aneka is a platform for deploying Clouds developing applications on top of\\u000ait. It provides a runtime environment and a set of APIs that allow developers\\u000ato build .NET applications that leverage their computation on either public or\\u000aprivate clouds. One of the key features of Aneka is the ability of supporting\\u000amultiple programming models that are ways of expressing

Christian Vecchiola; Xingchen Chu; Rajkumar Buyya

2009-01-01

284

Extraction of Profile Information from Cloud Contaminated Radiances. Appendixes 2  

NASA Technical Reports Server (NTRS)

Clouds act to reduce the signal level and may produce noise dependence on the complexity of the cloud properties and the manner in which they are treated in the profile retrieval process. There are essentially three ways to extract profile information from cloud contaminated radiances: (1) cloud-clearing using spatially adjacent cloud contaminated radiance measurements, (2) retrieval based upon the assumption of opaque cloud conditions, and (3) retrieval or radiance assimilation using a physically correct cloud radiative transfer model which accounts for the absorption and scattering of the radiance observed. Cloud clearing extracts the radiance arising from the clear air portion of partly clouded fields of view permitting soundings to the surface or the assimilation of radiances as in the clear field of view case. However, the accuracy of the clear air radiance signal depends upon the cloud height and optical property uniformity across the two fields of view used in the cloud clearing process. The assumption of opaque clouds within the field of view permits relatively accurate profiles to be retrieved down to near cloud top levels, the accuracy near the cloud top level being dependent upon the actual microphysical properties of the cloud. The use of a physically correct cloud radiative transfer model enables accurate retrievals down to cloud top levels and below semi-transparent cloud layers (e.g., cirrus). It should also be possible to assimilate cloudy radiances directly into the model given a physically correct cloud radiative transfer model using geometric and microphysical cloud parameters retrieved from the radiance spectra as initial cloud variables in the radiance assimilation process. This presentation reviews the above three ways to extract profile information from cloud contaminated radiances. NPOESS Airborne Sounder Testbed-Interferometer radiance spectra and Aqua satellite AIRS radiance spectra are used to illustrate how cloudy radiances can be used in the profile retrieval process.

Smith, W. L.; Zhou, D. K.; Huang, H.-L.; Li, Jun; Liu, X.; Larar, A. M.

2003-01-01

285

Prediction Based Design of Fire Detection for Buildings with Ceiling Heights between 9m and 18m  

NASA Technical Reports Server (NTRS)

The purpose of this paper is to provide the experimental and theoretical background necessary to extend guidelines to ceiling heights between 9 m and 18 m. Based on the results of experiments conducted in 15 m and 22 m high hangars, detector activation thresholds and detector spacing are analyzed for both smoke and heat detectors. Only ceiling mounted detection devices are analyzed in this paper. In addition to the detector threshold study, the predictive capabilities of computer fire model simulations were compared with experimental results. This comparison, which is based on 12 fire tests, resulted in the development of a new ceiling jet algorithm to model phenomena which had not been included in previous algorithms. The improved algorithm provides a better representation of the development of the ceiling jet temperature to a growing hot layer and a better estimation of plume centerline temperature. Guidelines are examined, based on the experimental results, for fire detector spacing, placement, and sensitivity. Recommendations concerning the use of computer fire models at these heights are made as a function of fire size and hot layer development. The role of draft curtains is discussed and their impact on detector activation is demonstrated.

Davis, W. D.; Notarianni, K. A.

1998-01-01

286

4-D Display Of Satellite Cloud Images  

NASA Astrophysics Data System (ADS)

A technique has been developed to display GOES satellite cloud images in perspective over a topographical map. Cloud heights are estimated using temperatures from an infrared (IR) satellite image, surface temperature observations, and a climatological model of vertical temperature profiles. Cloud levels are discriminated from each other and from the ground using a pattern recognition algorithm based on the brightness variance technique of Coakley and Bretherton. The cloud regions found by the pattern recognizer are rendered in three-dimensional perspective over a topographical map by an efficient remap of the visible image. The visible shades are mixed with an artificial shade based on the geometry of the cloud-top surface, in order to enhance the texture of the cloud top.

Hibbard, William L.

1988-01-01

287

CloudPass - a passport system based on Cloud Computing and Near Field Communication  

E-print Network

Wireless communication has penetrated into all fields of technology, especially in mobility, where wireless transactions are gaining importance with improvements in standards like 3G and 4G. There are many technologies that support the wireless forms of interactions between devices. One among them is NFC - Near Field Communication. In addition to NFC, other external technologies like Quick Response (QR) Codes assist in establishing interactions among participating devices. In this paper, we examine an approach that will involve standards and technologies like NFC, QR Codes and Cloud Infrastructure to design a mobile application which will perform desired functionalities. Cloud Storage is used as a reservoir to store the artifacts used by the application. Development and testing of the application is initially carried out on emulators or simulators followed by testing on real handsets/devices.

Sudarsanan, Adethya

2012-01-01

288

A shape-based segmentation method for mobile laser scanning point clouds  

NASA Astrophysics Data System (ADS)

Segmentation of mobile laser point clouds of urban scenes into objects is an important step for post-processing (e.g., interpretation) of point clouds. Point clouds of urban scenes contain numerous objects with significant size variability, complex and incomplete structures, and holes or variable point densities, raising great challenges for the segmentation of mobile laser point clouds. This paper addresses these challenges by proposing a shape-based segmentation method. The proposed method first calculates the optimal neighborhood size of each point to derive the geometric features associated with it, and then classifies the point clouds according to geometric features using support vector machines (SVMs). Second, a set of rules are defined to segment the classified point clouds, and a similarity criterion for segments is proposed to overcome over-segmentation. Finally, the segmentation output is merged based on topological connectivity into a meaningful geometrical abstraction. The proposed method has been tested on point clouds of two urban scenes obtained by different mobile laser scanners. The results show that the proposed method segments large-scale mobile laser point clouds with good accuracy and computationally effective time cost, and that it segments pole-like objects particularly well.

Yang, Bisheng; Dong, Zhen

2013-07-01

289

Automated cloud classification using a ground based infra-red camera and texture analysis techniques  

NASA Astrophysics Data System (ADS)

Clouds play an important role in influencing the dynamics of local and global weather and climate conditions. Continuous monitoring of clouds is vital for weather forecasting and for air-traffic control. Convective clouds such as Towering Cumulus (TCU) and Cumulonimbus clouds (CB) are associated with thunderstorms, turbulence and atmospheric instability. Human observers periodically report the presence of CB and TCU clouds during operational hours at airports and observatories; however such observations are expensive and time limited. Robust, automatic classification of cloud type using infrared ground-based instrumentation offers the advantage of continuous, real-time (24/7) data capture and the representation of cloud structure in the form of a thermal map, which can greatly help to characterise certain cloud formations. The work presented here utilised a ground based infrared (8-14 ?m) imaging device mounted on a pan/tilt unit for capturing high spatial resolution sky images. These images were processed to extract 45 separate textural features using statistical and spatial frequency based analytical techniques. These features were used to train a weighted k-nearest neighbour (KNN) classifier in order to determine cloud type. Ground truth data were obtained by inspection of images captured simultaneously from a visible wavelength colour camera at the same installation, with approximately the same field of view as the infrared device. These images were classified by a trained cloud observer. Results from the KNN classifier gave an encouraging success rate. A Probability of Detection (POD) of up to 90% with a Probability of False Alarm (POFA) as low as 16% was achieved.

Rumi, Emal; Kerr, David; Coupland, Jeremy M.; Sandford, Andrew P.; Brettle, Mike J.

2013-10-01

290

Distinguishing cirrus cloud presence in autonomous lidar measurements  

NASA Astrophysics Data System (ADS)

2012 Level-2 Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) satellite-based cloud data sets are investigated for thresholds that distinguish the presence of cirrus clouds in autonomous lidar measurements, based on temperatures, heights, optical depth and phase. A thermal threshold, proposed by Sassen and Campbell (2001) for cloud top temperature Ttop ? -37 °C, is evaluated versus CALIOP algorithms that identify ice-phase cloud layers using polarized backscatter measurements. Derived global mean cloud top heights (11.15 vs. 10.07 km above mean sea level; a.m.s.l.), base heights (8.76 km a.m.s.l. vs. 7.95 km a.m.s.l.), temperatures (-58.48 °C vs. -52.18 °C and -42.40 °C vs. -38.13 °C, respectively, for tops and bases) and optical depths (1.18 vs. 1.23) reflect the sensitivity to this constraint. Over 99 % of all Ttop ? -37 °C clouds are classified as ice by CALIOP Level-2 algorithms. Over 81 % of all ice clouds correspond with Ttop ? -37 °C. For instruments lacking polarized measurements, and thus practical estimates of phase, Ttop ? -37 °C provides sufficient justification for distinguishing cirrus, as opposed to the risks of glaciated liquid-water cloud contamination occurring in a given sample from clouds identified at relatively "warm" (Ttop > -37 °C) temperatures. Although accounting for uncertainties in temperatures collocated with lidar data (i.e., model reanalyses/sondes) may justifiably relax the threshold to include warmer cases, the ambiguity of "warm" ice clouds cannot be fully reconciled with available measurements, conspicuously including phase. Cloud top heights and optical depths are investigated, and global distributions and frequencies derived, as functions of CALIOP-retrieved phase. These data provide little additional information, compared with temperature alone, and may exacerbate classification uncertainties overall.

Campbell, J. R.; Vaughan, M. A.; Oo, M.; Holz, R. E.; Lewis, J. R.; Welton, E. J.

2015-01-01

291

The Cloud Detection and Ultraviolet Monitoring Experiment (CLUE)  

NASA Technical Reports Server (NTRS)

In this paper we describe a new balloon instrument - CLUE - which is designed to monitor ultraviolet (uv) nightglow levels and determine cloud cover and cloud heights with a CO2 slicing technique. The CO2 slicing technique is based on the MODIS instrument on NASA's Aqua and Terra spacecraft. CLUE will provide higher spatial resolution (0.5 km) and correlations between the uv and the cloud cover.

Barbier, Louis M.; Loh, Eugene C.; Krizmanic, John F.; Sokolsky, Pierre; Streitmatter, Robert E.

2004-01-01

292

Vertical Structure of Ice Cloud Layers From CloudSat and CALIPSO Measurements and Comparison to NICAM Simulations  

NASA Technical Reports Server (NTRS)

The shape of the vertical profile of ice cloud layers is examined using 4 months of CloudSat and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) global measurements taken on January, April, July, and October 2007. Ice clouds are selected using temperature profiles when the cloud base is located above the 253K temperature level. The obtained ice water content (IWC), effective radius, or extinction coefficient profiles are normalized by their layer mean values and are expressed in the normalized vertical coordinate, which is defined as 0 and 1 at the cloud base and top heights, respectively. Both CloudSat and CALIPSO observations show that the maximum in the IWC and extinction profiles shifts toward the cloud bottom, as the cloud depth increases. In addition, clouds with a base reaching the surface in a high-latitude region show that the maximum peak of the IWC and extinction profiles occurs near the surface, which is presumably due to snow precipitation. CloudSat measurements show that the seasonal difference in normalized cloud vertical profiles is not significant, whereas the normalized cloud vertical profile significantly varies depending on the cloud type and the presence of precipitation. It is further examined if the 7 day Nonhydrostatic Icosahedral Atmospheric Model (NICAM) simulation results from 25 December 2006 to 1 January 2007 generate similar cloud profile shapes. NICAM IWC profiles also show maximum peaks near the cloud bottom for thick cloud layers and maximum peaks at the cloud bottom for low-level clouds near the surface. It is inferred that oversized snow particles in the NICAM cloud scheme produce a more vertically inhomogeneous IWC profile than observations due to quick sedimentation.

Ham, Seung-Hee; Sohn, Byung-Ju; Kato, Seiji; Satoh, Masaki

2013-01-01

293

Peeking Through The Cloud: DNS-based estimation and its applications  

E-print Network

Peeking Through The Cloud: DNS-based estimation and its applications Moheeb Abu Rajab1 , Fabian propose a new estimation technique that uses DNS cache probing to infer the den- sity of clients accessing

Amir, Yair

294

A novel method using Gabor-based multiple feature and ensemble SVMs for ground-based cloud classification  

NASA Astrophysics Data System (ADS)

Cloud recognition is the base of weather forecast and the recognition of cloud types is challenging because the texture of the clouds is extremely variable under different atmospheric conditions. In this paper, we propose a novel method for ground-based cloud classification. Firstly, the interest operator feature (IO) and the sorted spectral histogram (SSH) feature are generated from Gabor-filtered images and then they are selected by using the principal component analysis (PCA), which can reduce the feature's dimension. Secondly the new training set is selected using the supervised clustering technology. Finally we send the two features to the multi-class SVM classifier, and a voting algorithm is used to determine the category of each cloud. In practice, we find no single feature is best suited for recognizing all these classes. The result shows that this method has higher classfication accuracy and lower space complexity than the other methods.

Liu, Ruitao; Yang, Weidong

2011-11-01

295

Cloud Properties Derived from Surface-Based Near-Infrared Spectral Transmission  

NASA Technical Reports Server (NTRS)

Surface based near-infrared cloud spectral transmission measurements from a recent precipitation/cloud physics field study are used to determine cloud physical properties and relate them to other remote sensing and in situ measurements. Asymptotic formulae provide an effective means of closely approximating the qualitative and quantitative behavior of transmission computed by more laborious detailed methods. Relationships derived from asymptotic formulae are applied to measured transmission spectra to test objectively the internal consistency of data sets acquired during the field program and they confirmed the quality of the measurements. These relationships appear to be very useful in themselves, not merely as a quality control measure, but also a potentially valuable remote-sensing technique in its own right. Additional benefits from this analysis have been the separation of condensed water (cloud) transmission and water vapor transmission and the development of a method to derive cloud liquid water content.

Pilewskie, Peter; Twomey, S.; Gore, Warren J. Y. (Technical Monitor)

1996-01-01

296

Keypoint based autonomous registration of terrestrial laser point-clouds  

NASA Astrophysics Data System (ADS)

Registration of terrestrial laser scanning point-clouds involves handling huge datasets, irregular point distribution, multiple views, and relatively low textured surfaces. Common approaches for the registration are based in large on the iterative closest point (ICP) model, which is non-linear and requires good initial values to secure convergence to the actual solution. Computation of the initial approximations to launch the ICP algorithm requires the extraction of distinct features, devising methods for matching them among the datasets, and then computing the transformation parameters. In this paper we present a computational approach for the registration problem. In essence we exploit 3D rigid-body transformation invariant features to reduce significantly the computational load involved in the matching between key features. Generally, with the partial overlap among datasets and among the extracted features the identification of corresponding key features can be viewed as a sub-graph matching problem. This problem is hard to solve, but as the actual matched entities are subjected to a six parameters transformation it becomes manageable. We show that distances, which are invariant to rigid body transformation, can be applied for solving this problem. We then show that by using selected keypoints, the matching process can be optimized. We also show how the information embedded within the range data is utilized to improve the quality of the selected points. Following the presentation of our algorithm, we demonstrate its application on a sequence of scans taken in areas featuring a clutter of objects. Results and the analysis show its efficiency and robustness.

Barnea, Shahar; Filin, Sagi

297

Sensitivity of a physically-based cloud package in the NCAR/CCM2  

SciTech Connect

Based on our earlier investigation on the performance of the National Center for Atmospheric Research Community Climate Model Version 2 (CCM2), we have incorporated into this model a physically-based cloud package. This package allows for the prognostic computation of cloud liquid water which is advected using the semi-Lagrangrian transport scheme of CCM2 the formation of anvil clouds from deep convective systems, and the coupling of physically based cloud optical properties to the CCM2`s shortwave and longwave radiation treatment. In this paper, the effect of the cloud package is assessed by comparing the January results of the simulation to model output from a control run over the same period using the original version of CCM2. The model results are also compared to data from the global reanalysis for the same period conducted by the National Center for Experimental Prediction (NCEP) and NCAR. In this paper, we place particular emphasis on the cloud package`s effect on the climate patterns in the Pacific North American Region. The sensitivity of the model performance to the threshold relative humidity for cloud formation in the scheme is also assessed.

Kao, Chih-Yue Jim [Los Alamos National Lab., NM (United States); Smith, W.S. [Scripps Institution of Oceanography, La Jolla, CA (United States)

1997-02-01

298

A new NASA/MSFC mission analysis global cloud cover data base  

NASA Technical Reports Server (NTRS)

A global cloud cover data set, derived from the USAF 3D NEPH Analysis, was developed for use in climate studies and for Earth viewing applications. This data set contains a single parameter - total sky cover - separated in time by 3 or 6 hr intervals and in space by approximately 50 n.mi. Cloud cover amount is recorded for each grid point (of a square grid) by a single alphanumeric character representing each 5 percent increment of sky cover. The data are arranged in both quarterly and monthly formats. The data base currently provides daily, 3-hr observed total sky cover for the Northern Hemisphere from 1972 through 1977 less 1976. For the Southern Hemisphere, there are data at 6-hr intervals for 1976 through 1978 and at 3-hr intervals for 1979 and 1980. More years of data are being added. To validate the data base, the percent frequency of or = 0.3 and or = 0.8 cloud cover was compared with ground observed cloud amounts at several locations with generally good agreement. Mean or other desired cloud amounts can be calculated for any time period and any size area from a single grid point to a hemisphere. The data base is especially useful in evaluating the consequence of cloud cover on Earth viewing space missions. The temporal and spatial frequency of the data allow simulations that closely approximate any projected viewing mission. No adjustments are required to account for cloud continuity.

Brown, S. C.; Jeffries, W. R., III

1985-01-01

299

A Principal Component-Based Radiative Transfer Forward Model (PCRTM) for Vertically in Homogeneous Cloud  

NASA Technical Reports Server (NTRS)

A principal-component based radiative transfer model (PCRTM) is developed for simulating the infrared spectral radiance at the top of the atmosphere (TOA). The PCRTM approach removes the redundancy in radiative transfer calculation in high resolution infrared spectra, and saves significant amount of computational time with great accuracy. In PCRTM, both ice and water clouds are treated as effective transmissivity and reflectivity stored in a pre-calculated lookup tables. These quantities are calculated using cloud single scattering properties such as cloud optical depth, cloud particle size, cloud phase, etc. The cloud can be inserted into any pressure layer in the PCRTM model (up to 100 layers). The effective temperature of each cloud layer is treated as a function of its optical depth. To test the accuracy of this approximation, the results are compared with the more rigorous DISORT model, which treats cloud as a plane parallel layer. The root-mean-square error of PCRTM, with respect to DISORT results, is generally less than 0.5 K in brightness temperature. However, the CPU time required by PCRTM was approximately two orders of magnitude less than that required by DISORT.

Li, Hui; Liu, Xu; Yang, Ping; Kratz, David P.

2010-01-01

300

Ground-based remote sensing of thin clouds in the Arctic  

NASA Astrophysics Data System (ADS)

This paper describes a method for using interferometer measurements of downwelling thermal radiation to retrieve the properties of single-layer clouds. Cloud phase is determined from ratios of thermal emission in three "micro-windows" where absorption by water vapor is particularly small. Cloud microphysical and optical properties are retrieved from thermal emission in two micro-windows, constrained by the transmission through clouds of stratospheric ozone emission. Assuming a cloud does not approximate a blackbody, the estimated 95% confidence retrieval errors in effective radius, visible optical depth, number concentration, and water path are, respectively, 10%, 20%, 38% (55% for ice crystals), and 16%. Applied to data from the Atmospheric Radiation Measurement program (ARM) North Slope of Alaska - Adjacent Arctic Ocean (NSA-AAO) site near Barrow, Alaska, retrievals show general agreement with ground-based microwave radiometer measurements of liquid water path. Compared to other retrieval methods, advantages of this technique include its ability to characterize thin clouds year round, that water vapor is not a primary source of retrieval error, and that the retrievals of microphysical properties are only weakly sensitive to retrieved cloud phase. The primary limitation is the inapplicability to thicker clouds that radiate as blackbodies.

Garrett, T. J.; Zhao, C.

2012-11-01

301

A Comparison of Satellite-Based Multilayered Cloud Detection Methods  

NASA Technical Reports Server (NTRS)

Both techniques show skill in detecting multilayered clouds, but they disagree more than 50% of the time. BTD method tends to detect more ML clouds than CO2 method and has slightly higher detection accuracy. CO2 method might be better for minimizing false positives, but further study is needed. Neither method as been optimized for GOES data. BTD technique developed on AVHRR, better BTD signals & resolution. CO2 developed on MODIS, better resolution & 4 CO2 channels. Many additional comparisons with ARSCL data will be used to optimize both techniques. A combined technique will be examined using MODIS & Meteosat-8 data. After optimization, the techniques will be implemented in the ARM operational satellite cloud processing.

Minnis, Patrick; Chang, Fu-Lung; Khaiyer, Mandana M.; Ayers, Jeffrey K.; Palikonda, Rabindra; Nordeen, Michele L.; Spangenberg, Douglas A.

2007-01-01

302

Stratiform Cloud—Inversion Characterization During the Arctic Melt Season  

NASA Astrophysics Data System (ADS)

Data collected during July and August from the Arctic Ocean Experiment 2001 illustrated a common occurrence of specific-humidity ( q) inversions, where moisture increases with height, coinciding with temperature inversions in the central Arctic boundary layer and lower troposphere. Low-level stratiform clouds and their relationship to temperature inversions are examined using radiosonde data and data from a suite of remote sensing instrumentation. Two low-level cloud regimes are identified: the canonical case of stratiform clouds, where the cloud tops are capped by the temperature inversion base (CCI—Clouds Capped by Inversion) and clouds where the cloud tops were found well inside the inversion (CII—Clouds Inside Inversion). The latter case was found to occur more than twice as frequently than the former. The characteristic of the temperature inversion is shown to have an influence on the cloud regime that was supported. Statistical analyses of the cloud regimes using remote sensing instruments suggest that CCI cases tend to be dominated by single-phase liquid cloud droplets; radiative cooling at the cloud top limits the vertical extent of such clouds to the inversion base height. The CII cases, on the other hand, display characteristics that can be divided into two situations—(1) clouds that only slightly penetrate the temperature inversion and exhibit a microphysical signal similar to CCI cases, or (2) clouds that extend higher into the inversion and show evidence of a mixed-phase cloud structure. An important interplay between the mixed-phase structure and an increased potential for turbulent mixing across the inversion base appears to support the lifetime of CII cases existing within the inversion layer.

Sedlar, Joseph; Tjernström, Michael

2009-09-01

303

Integration of cloud-based storage in BES III computing environment  

NASA Astrophysics Data System (ADS)

We present an on-going work that aims to evaluate the suitability of cloud-based storage as a supplement to the Lustre file system for storing experimental data for the BES III physics experiment and as a backend for storing files belonging to individual members of the collaboration. In particular, we discuss our findings regarding the support of cloud-based storage in the software stack of the experiment. We report on our development work that improves the support of CERN' s ROOT data analysis framework and allows efficient remote access to data through several cloud storage protocols. We also present our efforts providing the experiment with efficient command line tools for navigating and interacting with cloud storage-based data repositories both from interactive sessions and grid jobs.

Wang, L.; Hernandez, F.; Deng, Z.

2014-06-01

304

The height variation of supergranular velocity fields determined from simultaneous OSO 8 satellite and ground-based observations  

NASA Technical Reports Server (NTRS)

Results are reported for simultaneous satellite and ground-based observations of supergranular velocities in the sun, which were made using a UV spectrometer aboard OSO 8 and a diode-array instrument operating at the exit slit of an echelle spectrograph attached to a vacuum tower telescope. Observations of the steady Doppler velocities seen toward the limb in the middle chromosphere and the photosphere are compared; the observed spectral lines of Si II at 1817 A and Fe I at 5576 A are found to differ in height of formation by about 1400 km. The results show that supergranular motions are able to penetrate at least 11 density scale heights into the middle chromosphere, that the patterns of motion correlate well with the cellular structure seen in the photosphere, and that the motion increases from about 800 m/s in the photosphere to at least 3000 m/s in the middle chromosphere. These observations imply that supergranular velocities should be evident in the transition region and that strong horizontal shear layers in supergranulation should produce turbulence and internal gravity waves.

November, L. J.; Toomre, J.; Gebbie, K. B.; Simon, G. W.

1979-01-01

305

Polar Stratospheric Clouds from ground-based lidar and CALIPSO observations and Chemistry Climate Models evaluation  

NASA Astrophysics Data System (ADS)

We evaluate the Antarctic PSC observational databases of CALIPSO and the ground-based lidars of NDACC (Network for Detection of Atmospheric Composition Changes) located in McMurdo and Dumont D'Urville stations and provide a process-oriented evaluation of PSC in a subset of CCMVAL-2 chemistry-climate models. Lidar observatories have a decadal coverage, albeit with discontinuities, spanning from 1992 to today hence offering a unique database. A clear issue is the representativeness of ground-based long-term data series of the Antarctic stratosphere conditions that may limit their value in climatological studies and model evaluation. The comparison with the CALIPSO observations with a global coverage is, hence, a key issue. In turn, models can have a biased representation of the stratospheric conditions and of the PSC microphysics leading to large discrepancies in PSC occurrence and composition. CALIPSO observations indicate a large longitudinal variability in PSC formation in the polar atmosphere and ground-based observations are hence representative of different cloud conditions. Point-to-point comparison is difficult due to sparseness of the database (or PSC appearance at the edge of the vortex) and to intrinsic differences in spatial distribution between models and observations. So the use of simple diagnostics that are independent from instrumental coverage is fundamental. Comparison between ground-based and satellite borne-lidar is overall satisfactory and differences may be attributed to differences in coverage. As expected, McMurdo site is dominated by a NAT-type regime that is a clear feature of the eastern part of polar vortex while Dumont D'Urville is largely influenced by the transition at the edge the polar vortex resulting, on average, in a much reduced PSC coverage with a partition between NAT and STS cloud types. Data from the 5 CCMs having provided PSC surface areas on daily basis have been evaluated using the same diagnostic type that may be derived CALIPSO (i.e. frequency of PSC occurrence function of lon-lat, height and temperature) showing large differences that may be explained by the interplay of model temperatures that may show a large bias (negative for 3 models over 5) and the microphysical scheme itself. Two models in fact show an excess of NAT formation relative to ice clouds while two others have an unrealistic dominance of ice. Most of them show a somewhat too efficient PSC production with temperature decrease below NAT formation temperature. Evaluation CCMs with ground-based instruments databases should be done with great care due to the large spatial differences inside the polar vortex that are not fully reproduced by the models. In turn, longer series as provided by NDACC should be used to evaluate interannual variability and trends that is difficult to identify in the shorter CALIPSO database.

Fierli, Federico; Di Liberto, Luca; Cairo, Francesco; Cagnazzo, Chiara; Snels, Marcel; Keckhut, Philippe; Jumelet, Julien; Pitts, Michael C.

2014-05-01

306

PBL Height in a Clear and Cloudy Layer  

NASA Astrophysics Data System (ADS)

In this paper it is presented and compared some characteristics of the Planetary Boundary Layer in the presence and absence of clouds. It is well know (Garstang and Fitzjarrald, 1999) that the simple concept of a boundary layer holds only in the absence of convective clouds. When clouds are presented the connection between the surface and the atmosphere are due to cloud-induced motions. In July-August 2008 a micrometeorological campaign was developed in a near homogeneous surface in the south of Brazil. Micrometeorological data was collected over a 7-week time and the database comprises measurements of wind speed, wind direction, turbulence, temperature, humidity, pressure and solar radiation. Energy budgets as well as statistics of turbulence parameters are then computed in a classical way. Measurements with tethered balloon were also performed in order to determine structure and linkages of the convection in the lower cloud, at the cloud base, and in the mixed and surface layers below the cloud. Hence, the purposes of the present study is to focus on the characteristics of the PBL as well as its height determination during clear sky and under cloudy conditions using observational dataset and LES model. Reference Garstang, M. and Fitzjarrald, D., 1999, Observations of surface to atmosphere interactions in the tropics, Oxford University Press, 405pp.

Moraes, O.

2009-09-01

307

Incomplete Points Cloud Data Surface Reconstruction Based on Neural Network  

Microsoft Academic Search

Neural network arithmetic was employed in incomplete points cloud data surface reconstruction, Radial basis function neural network and simulated annealing arithmetic was combined. The new arithmetic can approach any nonlinear function by arbitrary precision, and also keep the network from getting into local minimum. Global optimization feature of simulated annealing was employed to adjust the network weights. MATLAB program was

Xue-mei Wu; Gui-xian Li; Wei-min Zhao

2008-01-01

308

An E-learning Ecosystem Based on Cloud Computing Infrastructure  

Microsoft Academic Search

Recently the research community has believed that an e-learning ecosystem is the next generation e- learning. However, the current models of e-learning ecosystems lack the support of underlying infrastructures, which can dynamically allocate the required computation and storage resources for e- learning ecosystems. Cloud computing is a promising infrastructure which provides computation and storage resources as services. Hence, this paper

Bo Dong; Qinghua Zheng; Jie Yang; Haifei Li; Mu Qiao

2009-01-01

309

Towards a quantification of ocean wave heights off the west coast of Ireland using land based seismic data  

NASA Astrophysics Data System (ADS)

Ocean gravity waves are driven by atmospheric pressure systems. Their interactions with one another and reflection off coastlines generate pressure changes at the sea floor. These pressure fluctuations are the cause of continuous background seismic noise known as microseisms. The levels of microseism activity vary as a function of the sea state and increase during periods of intensive ocean wave activity. In 2011 a seismic network was deployed along the west coast of Ireland to continuously record microseisms generated in the Atlantic Ocean, as part of the Wave Observation (WaveObs) project based in University College Dublin. This project aims to determine the characteristics of the causative ocean gravity waves through calibration of the microseism data with ocean buoy data. In initial tests we are using a Backpropagation Feed-forward Artificial Neural Network (BP ANN) to establish the underlying relationships between microseisms and ocean waves. ANNs were originally inspired by studies of the mammalian brain and nervous system and are designed to learn by example. If successful these tools could then be used to estimate ocean wave heights and wave periods using a land-based seismic network and complement current wave observations being made offshore by marine buoys. Preliminary ANN results are promising with the network successfully able to reconstruct trends in ocean wave heights and periods. Microseisms can provide significant information about oceanic processes. With a deeper understanding of how these processes work there is potential for 1) locating and tracking the evolution of the largest waves in the Atlantic and 2) reconstructing the wave climate off the west coast of Ireland using legacy seismic data on a longer time scale than is currently available using marine based observations.

Donne, S.; Bean, C. J.; Lokmer, I.; Lambkin, K.; Creamer, C.

2012-12-01

310

Non-Precipitating Stratus Cloud Images Retrieval and Characterization Using a Ground-Based Dual-Wavelength  

E-print Network

Non-Precipitating Stratus Cloud Images Retrieval and Characterization Using a Ground-Based Dual at Amherst ABSTRACT Characterization of the microphysical properties of non-precipitating stratus clouds. INTRODUCTION Stratus clouds frequently cover much of the sky and play a key role in keeping Earth's surface

Cruz-Pol, Sandra L.

311

THE CLOUDSAT MISSION AND THE A-TRAIN A New Dimension of Space-Based Observations of Clouds and Precipitation  

E-print Network

THE CLOUDSAT MISSION AND THE A-TRAIN A New Dimension of Space-Based Observations of Clouds of the images of earth from space are the clouds that move around our planet in quasi-organized large- scale. Clouds also dominate the energy budget of the planet. They tend to cool the earth by reflecting sunlight

312

Global distribution of total cloud cover and cloud type amounts over the ocean  

SciTech Connect

This is the fourth of a series of atlases to result from a study of the global cloud distribution from ground-based observations. The first two atlases (NCAR/TN-201+STR and NCAR/TN-241+STR) described the frequency of occurrence of each cloud type and the co-occurrence of different types, but included no information about cloud amounts. The third atlas (NCAR/TN-273+STR) described, for the land areas of the earth, the average total cloud cover and the amounts of each cloud type, and their geographical, diurnal, seasonal, and interannual variations, as well as the average base heights of the low clouds. The present atlas does the same for the ocean areas of the earth.

Warren, S.G.; Hahn, C.J.; London, J.; Chervin, R.M.; Jenne, R.L. (Washington Univ., Seattle, WA (USA). Dept. of Atmospheric Sciences; Colorado Univ., Boulder, CO (USA). Cooperative Inst. for Research in Environmental Sciences; Colorado Univ., Boulder, CO (USA). Dept. of Astrophysical, Planetary, and Atmospheric Sciences; National Center for Atmospheric Research, Boulder, CO (USA))

1988-12-01

313

Island based radar and microwave radiometer measurements of stratus cloud parameters during the Atlantic Stratocumulus Transition Experiment (ASTEX)  

SciTech Connect

During the Atlantic Stratocumulus Transition Experiment (ASTEX) in June 1992, simultaneous measurements were made with a vertically pointing cloud sensing radar and a microwave radiometer. The radar measurements are used to estimate stratus cloud drizzle and turbulence parameters. In addition, with the microwave radiometer measurements of reflectivity, we estimated the profiles of cloud liquid water and effective radius. We used radar data for computation of vertical profiles of various drizzle parameters such as droplet concentration, modal radius, and spread. A sample of these results is shown in Figure 1. In addition, in non-drizzle clouds, with the radar and radiometer we can estimate the verticle profiles of stratus cloud parameters such as liquid water concentration and effective radius. This is accomplished by assuming a droplet distribution with droplet number concentration and width constant with height.

Frisch, A.S. [Colorado State Univ., Fort Collins, CO (United States); Fairall, C.W.; Snider, J.B. [NOAA Environmental Technology Lab., Boulder, CO (United States); Lenshow, D.H.; Mayer, S.D. [National Center for Atmospheric Research, Boulder, CO (United States)

1996-04-01

314

Measuring Height without a Stadiometer  

PubMed Central

Objectives To compare whether four methods to measure or estimate height among wheelchair users result in significantly different estimates and to determine which method is most accurate. Design Height data were obtained for 141 wheelchair users. Height estimates included asking for self-report and measuring recumbent length, knee height, and armspan. All analyses were conducted separately for men and women. A two-group confirmatory factor analysis assessed which measure provided the best estimate of height in this population. It also tested the measurement invariance of the four height estimates between men and women and whether there were significant differences across these estimates within each sex. Results CFA findings indicated that the four measures yielded significantly different height estimates and BMI values for both men and women. For both sexes, armspan resulted in the longest estimate and measured recumbent length the shortest, with the reverse pattern for BMI values. The common variance estimates were outstanding for recumbent length (92%) and knee height (>83%) and very good for self-report (>75%), while the common variance for armspan was poor (<42%). Conclusions The measurement method used to estimate height yields significantly different values for both height and BMI among wheelchair users who cannot stand to be measured using a stadiometer. Recumbent length yields the most accurate height estimate for wheelchair users. However, when logistical and practical considerations pose difficulties for obtaining this measure, height estimates based on knee height and self-report may provide reasonable alternatives. PMID:21681063

Froehlich-Grobe, Katherine; Nary, Dorothy E.; Van Sciver, Angela; Lee, Jaehoon; Little, Todd D.

2011-01-01

315

Development and clinical study of mobile 12-lead electrocardiography based on cloud computing for cardiac emergency.  

PubMed

To improve emergency services for accurate diagnosis of cardiac emergency, we developed a low-cost new mobile electrocardiography system "Cloud Cardiology®" based upon cloud computing for prehospital diagnosis. This comprises a compact 12-lead ECG unit equipped with Bluetooth and Android Smartphone with an application for transmission. Cloud server enables us to share ECG simultaneously inside and outside the hospital. We evaluated the clinical effectiveness by conducting a clinical trial with historical comparison to evaluate this system in a rapid response car in the real emergency service settings. We found that this system has an ability to shorten the onset to balloon time of patients with acute myocardial infarction, resulting in better clinical outcome. Here we propose that cloud-computing based simultaneous data sharing could be powerful solution for emergency service for cardiology, along with its significant clinical outcome. PMID:23920851

Fujita, Hideo; Uchimura, Yuji; Waki, Kayo; Omae, Koji; Takeuchi, Ichiro; Ohe, Kazuhiko

2013-01-01

316

Cloud optical depth dependence on temperature from ground-based observations  

NASA Astrophysics Data System (ADS)

The relationship between cloud optical depth and cloud temperature has been explored using satellite data and global climate modeling results (Tselioudis et al 1992; Gordon and Klein 2012). Based on ground-based observations from DOE Atmospheric Radiation Measurement (ARM) program, we extend the approach in Del Genio and Wolf (2002) to 1) provide a more accurate quantification of the relationship and 2) explore physical mechanisms that determine the relationship. We focus on single layer overcast clouds, separate the change of cloud optical depth with temperature due to seasonal variation, diurnal cycle and synoptic variability, and explore potential interaction with atmospheric boundary layers. The resulted relationship will be compared with satellite observations and will be used to evaluate global climate model results at ARM sites. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Zhang, Y.; Gordon, N. D.; Klein, S. A.

2012-12-01

317

COMBAT: mobile-Cloud-based cOmpute/coMmunications infrastructure for BATtlefield applications  

NASA Astrophysics Data System (ADS)

The amount of data processed annually over the Internet has crossed the zetabyte boundary, yet this Big Data cannot be efficiently processed or stored using today's mobile devices. Parallel to this explosive growth in data, a substantial increase in mobile compute-capability and the advances in cloud computing have brought the state-of-the- art in mobile-cloud computing to an inflection point, where the right architecture may allow mobile devices to run applications utilizing Big Data and intensive computing. In this paper, we propose the MObile Cloud-based Hybrid Architecture (MOCHA), which formulates a solution to permit mobile-cloud computing applications such as object recognition in the battlefield by introducing a mid-stage compute- and storage-layer, called the cloudlet. MOCHA is built on the key observation that many mobile-cloud applications have the following characteristics: 1) they are compute-intensive, requiring the compute-power of a supercomputer, and 2) they use Big Data, requiring a communications link to cloud-based database sources in near-real-time. In this paper, we describe the operation of MOCHA in battlefield applications, by formulating the aforementioned mobile and cloudlet to be housed within a soldier's vest and inside a military vehicle, respectively, and enabling access to the cloud through high latency satellite links. We provide simulations using the traditional mobile-cloud approach as well as utilizing MOCHA with a mid-stage cloudlet to quantify the utility of this architecture. We show that the MOCHA platform for mobile-cloud computing promises a future for critical battlefield applications that access Big Data, which is currently not possible using existing technology.

Soyata, Tolga; Muraleedharan, Rajani; Langdon, Jonathan; Funai, Colin; Ames, Scott; Kwon, Minseok; Heinzelman, Wendi

2012-05-01

318

Maskless imaging of dense samples using pixel super-resolution based multi-height lensfree on-chip microscopy  

PubMed Central

Lensfree in-line holographic microscopy offers sub-micron resolution over a large field-of-view (e.g., ~24 mm2) with a cost-effective and compact design suitable for field use. However, it is limited to relatively low-density samples. To mitigate this limitation, we demonstrate an on-chip imaging approach based on pixel super-resolution and phase recovery, which iterates among multiple lensfree intensity measurements, each having a slightly different sample-to-sensor distance. By digitally aligning and registering these lensfree intensity measurements, phase and amplitude images of dense and connected specimens can be iteratively reconstructed over a large field-of-view of ~24 mm2 without the use of any spatial masks. We demonstrate the success of this multi-height in-line holographic approach by imaging dense Papanicolaou smears (i.e., Pap smears) and blood samples. PMID:22330550

Greenbaum, Alon; Ozcan, Aydogan

2012-01-01

319

Forecasting for Grid and Cloud Computing On-Demand Resources Based on Pattern Matching  

Microsoft Academic Search

Abstract: The Cloud phenomenon,brings along the cost-saving benefit of dynamic scaling. Knowledge in advance is necessary as the virtual resources that Cloud computing uses have a setup time that is not negligible. We propose a new approach to the problem of workload prediction based on identifying similar past occurrences to the current short-term workload history. We present in detail the

Eddy Caron; Frédéric Desprez; Adrian Muresan

2010-01-01

320

Analysis of global cloudiness. 2: Comparison of ground-based and satellite-based cloud climatologies  

SciTech Connect

Cloud climatologies are developed and intercompared for International Satellite Cloud Climatology Project (ISCCO) (1983-1988), Meteor I (1971-1980), Meteor II (1979-1988), and Nimbus 7 (1979-1985) satellite observations, and for Berlyand and Strokina (1975, 1980) and Warren et al. (1986, 1988) ground-based observations. The satellite annual-mean, global- mean cloudiness, 0.57 +/- 0.05, is less than the ground-based value, 0.61 +/- 0.01, predominantly because of the low value for Nimbus 7. There is agreement between the satellite means of ISCCP, 0.62, and Meteor II, 0.61, and the ground-based means of Warren et al., 0.62, and Berlyand and Strokina, 0.60. Each satellite- and ground-based climatology shows that the hemispheric- mean cloudiness is larger in summer than that in winter in both the northern and southern hemispheres. Excluding Nimbus 7 observations, the zonal- mean cloudiness distributions for January, July, and July minus January display reasonably good agreement between 60 deg S and 60 deg N. In polar latitudes there is significant disagreement among the different climatologies, even in the sign of cloudiness changes from winter to summer. This evinces the need for special cloudiness experiments in polar regions, particularly in winter and summer.

Mokhov, I.I.; Schlesinger, M.E. [Russian Academy of Science, Moscow (Russian Federation)]|[Univ. of Illinois, Urbana, IL (United States)

1994-08-01

321

Comprehensive Stability Evaluation of Rock Slope Using the Cloud Model-Based Approach  

NASA Astrophysics Data System (ADS)

This article presents the cloud model-based approach for comprehensive stability evaluation of complicated rock slopes of hydroelectric stations in mountainous area. This approach is based on membership cloud models which can account for randomness and fuzziness in slope stability evaluation. The slope stability is affected by various factors and each of which is ranked into five grades. The ranking factors are sorted into four categories. The ranking system of slope stability is introduced and then the membership cloud models are applied to analyze each ranking factor for generating cloud memberships. Afterwards, the obtained cloud memberships are synthesized with the factor weights given by experts for comprehensive stability evaluation of rock slopes. The proposed approach is used for the stability evaluation of the left abutment slope in Jinping 1 Hydropower Station. It is shown that the cloud model-based strategy can well consider the effects of each ranking factor and therefore is feasible and reliable for comprehensive stability evaluation of rock slopes.

Liu, Zaobao; Shao, Jianfu; Xu, Weiya; Xu, Fei

2014-11-01

322

Cloud Detection Method Based on Feature Extraction in Remote Sensing Images  

NASA Astrophysics Data System (ADS)

In remote sensing images, the existence of the clouds has a great impact on the image quality and subsequent image processing, as the images covered with clouds contain little useful information. Therefore, the detection and recognition of clouds is one of the major problems in the application of remote sensing images. Present there are two categories of method to cloud detection. One is setting spectrum thresholds based on the characteristics of the clouds to distinguish them. However, the instability and uncertainty of the practical clouds makes this kind of method complexity and weak adaptability. The other method adopts the features in the images to identify the clouds. Since there will be significant overlaps in some features of the clouds and grounds, the detection result is highly dependent on the effectiveness of the features. This paper presented a cloud detection method based on feature extraction for remote sensing images. At first, find out effective features through training pattern, the features are selected from gray, frequency and texture domains. The different features in the three domains of the training samples are calculated. Through the result of statistical analysis of all the features, the useful features are picked up to form a feature set. In concrete, the set includes three feature vectors, respectively, the gray feature vector constituted of average gray, variance, first-order difference, entropy and histogram, the frequency feature vector constituted of DCT high frequency coefficient and wavelet high frequency coefficient, and the texture feature vector constituted of the hybrid entropy and difference of the gray-gradient co-occurrence matrix and the image fractal dimension. Secondly, a thumbnail will be obtained by down sampling the original image and its features of gray, frequency and texture are computed. Last but not least, the cloud region will be judged by the comparison between the actual feature values and the thresholds determined by the sample training process. Experimental results show that the clouds and ground objects can be separated efficiently, and our method can implement rapid clouds detection and cloudiness calculation.

Changhui, Y.; Yuan, Y.; Minjing, M.; Menglu, Z.

2013-05-01

323

Analysis of Satellite-Based Polar Mesospheric Cloud Observations  

NASA Astrophysics Data System (ADS)

Polar Mesospheric Clouds (PMCs) are thin water-ice clouds that form in the summer polar mesopause region. Since PMCs are sensitive to changes in the upper atmospheric temperature and water vapor abundance, they can be used to understand the dynamics of the upper mesosphere. It has also been suggested that they are important indicators of mesospheric climate change. PMCs have been successfully observed from the ground and with remote sensing instruments, for example the Cloud Imaging and Particle Size (CIPS) experiment on the Aeronomy of Ice in the Mesosphere (AIM) satellite, and the Solar Backscatter UltraViolet (SBUV) instruments. This thesis presents validation of CIPS observations by showing a comparison of PMC occurrence frequency, cloud and background albedo as observed by CIPS and SBUV. It is found that frequency and cloud albedo are in excellent agreement, with a small (10%) low bias in the CIPS v3.20 operational frequencies at more equatorward PMC latitudes on the descending node. The background albedo, however, shows a still unresolved bias that depends on hemisphere. Overall, the results show that CIPS PMC data are valid for scientific analysis. Furthermore, this thesis investigates and quantifies the relative importance of several coupling mechanisms that contribute to variability in the PMC season onset, such as the solar cycle and intra-hemispheric and inter-hemispheric coupling. It is found that the Southern Hemisphere (SH) PMC season onset is controlled primarily by the timing of the SH stratospheric wind reversal from its winter to summer state, with a smaller but still important contribution from the solar cycle. Inter-hemispheric coupling triggered by winter stratospheric wind variations plays a significant role in controlling the Northern Hemisphere (NH) PMC season onset dates, again with additional control by the solar cycle. These couplings explain most of the observed variability in the PMC onset dates as observed by SBUV over the past three decades. Preliminary results indicate that the Specified Dynamics version of the Whole Atmosphere Community Climate Model (SD-WACCM) will be a useful tool for more detailed studies of the mechanisms that control PMC variability. Future studies extending the presented CIPS validation and PMC variability investigation are suggested.

Benze, Susanne

324

Clock-Based Proxy Re-encryption Scheme inClock-Based Proxy Re-encryption Scheme inClock-Based Proxy Re-encryption Scheme inClock-Based Proxy Re-encryption Scheme in Unreliable CloudsUnreliable CloudsUnreliable CloudsUnreliable Clouds  

E-print Network

International Workshop on Security in Cloud Computing (CloudSecInternational Workshop on Security in Cloud Computing (CloudSecInternational Workshop on Security in Cloud Computing (CloudSecInternational Workshop on Security in Cloud Computing (CloudSec 2012)2012)2012)2012) [1] Central South University, China [2] Temple

Wu, Jie

325

A cloud-based approach for interoperable electronic health records (EHRs).  

PubMed

We present a cloud-based approach for the design of interoperable electronic health record (EHR) systems. Cloud computing environments provide several benefits to all the stakeholders in the healthcare ecosystem (patients, providers, payers, etc.). Lack of data interoperability standards and solutions has been a major obstacle in the exchange of healthcare data between different stakeholders. We propose an EHR system - cloud health information systems technology architecture (CHISTAR) that achieves semantic interoperability through the use of a generic design methodology which uses a reference model that defines a general purpose set of data structures and an archetype model that defines the clinical data attributes. CHISTAR application components are designed using the cloud component model approach that comprises of loosely coupled components that communicate asynchronously. In this paper, we describe the high-level design of CHISTAR and the approaches for semantic interoperability, data integration, and security. PMID:25055368

Bahga, Arshdeep; Madisetti, Vijay K

2013-09-01

326

Remote sensing monitoring of volcanic ash clouds based on PCA method  

NASA Astrophysics Data System (ADS)

Volcanic ash clouds threaten the aviation safety and cause global environmental effects. It is possible to effectively monitor the volcanic ash cloud with the aid of thermal infrared remote sensing technology. Principal component analysis (PCA) is able to remove the inter-band correlation and eliminate the data redundancy of remote sensing data. Taking the Eyjafjallajokull volcanic ash clouds formed on 15 and 19 April 2010 as an example, in this paper, the PCA method is used to monitor the volcanic ash cloud based on MODIS bands selection; the USGS standard spectral database and the volcanic absorbing aerosol index (AAI) are applied as contrasts to the monitoring result. The results indicate that: the PCA method is much simpler; its spectral matching rates reach 74.65 and 76.35%, respectively; and the PCA method has higher consistency with volcanic AAI distribution.

Li, Chengfan; Dai, Yangyang; Zhao, Junjuan; Zhou, Shiqiang; Yin, Jingyuan; Xue, Dan

2014-12-01

327

Towards Composing Data Aware Systems Biology Workflows on Cloud Platforms: A MeDICi-based Approach  

SciTech Connect

Cloud computing is being increasingly adopted for deploying systems biology scientific workflows. Scientists developing these workflows use a wide variety of fragmented and competing data sets and computational tools of all scales to support their research. To this end, the synergy of client side workflow tools with cloud platforms is a promising approach to share and reuse data and workflows. In such systems, the location of data and computation is essential consideration in terms of quality of service for composing a scientific workflow across remote cloud platforms. In this paper, we describe a cloud-based workflow for genome annotation processing that is underpinned by MeDICi - a middleware designed for data intensive scientific applications. The workflow implementation incorporates an execution layer for exploiting data locality that routes the workflow requests to the processing steps that are colocated with the data. We demonstrate our approach by composing two workflowswith the MeDICi pipelines.

Gorton, Ian; Liu, Yan; Yin, Jian; Kulkarni, Anand V.; Wynne, Adam S.

2011-09-08

328

Model-Based Estimation of Forest Canopy Height in Red and Austrian Pine Stands Using Shuttle Radar Topography Mission and Ancillary Data: a Proof-of-Concept Study  

SciTech Connect

In this paper, accurate tree stand height retrieval is demonstrated using C-band Shuttle Radar Topography Mission (SRTM) height and ancillary data. The tree height retrieval algorithm is based on modeling uniform tree stands with a single layer of randomly oriented vegetation particles. For such scattering media, the scattering phase center height, as measured by SRTM, is a function of tree height, incidence angle, and the extinction coefficient of the medium. The extinction coefficient for uniform tree stands is calculated as a function of tree height and density using allometric equations and a fractal tree model. The accuracy of the proposed algorithm is demonstrated using SRTM and TOPSAR data for 15 red pine and Austrian pine stands (TOPSAR is an airborne interferometric synthetic aperture radar). The algorithm yields root-mean-square (rms) errors of 2.5-3.6 m, which is a substantial improvement over the 6.8-8.3-m rms errors from the raw SRTM minus National Elevation Dataset Heights.

Brown Jr., C G; Sarabandi, K; Pierce, L E

2007-04-06

329

A New Trusted and Collaborative Agent Based Approach for Ensuring Cloud Security  

E-print Network

In order to determine the user's trust is a growing concern for ensuring privacy and security in a cloud computing environment. In cloud, user's data is stored in one or more remote server(s) which poses more security challenges for the system. One of the most important concerns is to protect user's sensitive information from other users and hackers that may cause data leakage in cloud storage. Having this security challenge in mind, this paper focuses on the development of a more secure cloud environment, to determine the trust of the service requesting authorities by using a novel VM (Virtual Machine) monitoring system. Moreover, this research aims towards proposing a new trusted and collaborative agent-based two-tier framework, titled WAY (Who Are You?), to protect cloud resources. The framework can be used to provide security in network, infrastructure, as well as data storage in a heterogeneous cloud platform. If the trust updating policy is based on network activities, then the framework can provide net...

Pal, Shantanu; Chaki, Nabendu; Sanyal, Sugata

2011-01-01

330

Automatic Atlas Based Electron Density and Structure Contouring for MRI-based Prostate Radiation Therapy on the Cloud  

NASA Astrophysics Data System (ADS)

Our group have been developing methods for MRI-alone prostate cancer radiation therapy treatment planning. To assist with clinical validation of the workflow we are investigating a cloud platform solution for research purposes. Benefits of cloud computing can include increased scalability, performance and extensibility while reducing total cost of ownership. In this paper we demonstrate the generation of DICOM-RT directories containing an automatic average atlas based electron density image and fast pelvic organ contouring from whole pelvis MR scans.

Dowling, J. A.; Burdett, N.; Greer, P. B.; Sun, J.; Parker, J.; Pichler, P.; Stanwell, P.; Chandra, S.; Rivest-Hénault, D.; Ghose, S.; Salvado, O.; Fripp, J.

2014-03-01

331

Combined Geometric/radiometric Point Cloud Matching for Shear Analysis  

NASA Astrophysics Data System (ADS)

In the recent past, dense image matching methods such as Semi-Global Matching (SGM) became popular for many applications. The SGM approach has been adapted to and implemented for Leica ADS line-scanner data by North West Geomatics (North West) in co-operation with Leica Geosystems; it is used in North West's production workflow. One of the advantages of ADS imagery is the calibrated color information (RGB and near infrared), extending SGM-derived point clouds to dense "image point clouds" or, more general, information clouds (info clouds). With the goal of automating the quality control of ADS data, info clouds are utilized for Shear Analysis: Three-dimensional offsets of adjacent ADS image strips are determined from a pattern of info cloud pairs in strip overlaps by point cloud matching. The presented approach integrates geometry (height) and radiometry (intensity) information; matching is based on local point-to-plane distances for all points in a given cloud. The offset is derived in a least squares adjustment by applying it to each individual distance computation equation. Using intensities in addition to heights greatly benefits the offset computation, because intensity gradients tend to occur more frequently than height gradients. They can provide or complement the required information for the derivation of planimetric offset components. The paper details the combined geometric/radiometric point cloud matching approach and verifies the results against manual measurements.

Gehrke, S.

2012-07-01

332

Ground-based remote sensing of thin clouds in the Arctic  

NASA Astrophysics Data System (ADS)

This paper describes a method for using interferometer measurements of downwelling thermal radiation to retrieve the properties of single-layer clouds. Cloud phase is determined from ratios of thermal emission in three "micro-windows" at 862.5 cm-1, 935.8 cm-1, and 988.4 cm-1 where absorption by water vapour is particularly small. Cloud microphysical and optical properties are retrieved from thermal emission in the first two of these micro-windows, constrained by the transmission through clouds of primarily stratospheric ozone emission at 1040 cm-1. Assuming a cloud does not approximate a blackbody, the estimated 95% confidence retrieval errors in effective radius re, visible optical depth ?, number concentration N, and water path WP are, respectively, 10%, 20%, 38% (55% for ice crystals), and 16%. Applied to data from the Atmospheric Radiation Measurement programme (ARM) North Slope of Alaska - Adjacent Arctic Ocean (NSA-AAO) site near Barrow, Alaska, retrievals show general agreement with both ground-based microwave radiometer measurements of liquid water path and a method that uses combined shortwave and microwave measurements to retrieve re, ? and N. Compared to other retrieval methods, advantages of this technique include its ability to characterise thin clouds year round, that water vapour is not a primary source of retrieval error, and that the retrievals of microphysical properties are only weakly sensitive to retrieved cloud phase. The primary limitation is the inapplicability to thicker clouds that radiate as blackbodies and that it relies on a fairly comprehensive suite of ground based measurements.

Garrett, T. J.; Zhao, C.

2013-05-01

333

Towards the comparison of satellite- and ground-based cloud amount over China  

NASA Astrophysics Data System (ADS)

Cloud Amount (CA) is the dominant modulator of radiative fluxes. Satellite and ground observations act as two main sources for the global cloud climatology. In this study, we analyze the comparability of these two datasets over China. The MODIS cloud mask products which provide the pixel-based flag of cloudy or not is used to calculate satellite derived CA, while ground based CA is obtained from Synop stations which are visually estimated by observers. To match surface observations with MODIS data for comparison, a prerequisite is to determine the Effective Field of View (EFOV) of the ground observer. Instead of setting a constant EFOV, we firstly vary the radius of FOV for correlation analysis and find that a radius of 60 km is most useful for comparison purpose. The correlation coefficient ranges from 0.53 to 0.81 for different seasons, suggesting a significant relationship between satellite and ground based CA. Secondly, based on the estimated EFOV over China, an index of Effective Cloud Observation Density (ECOD) is introduced to evaluate the spatial distribution of Synop stations and the results show that western China has much lower ECOD than the eastern part. Finally, cloud fraction map and frequency distribution are applied to compare the two CA datasets and both indicate that MODIS derived and surface observed CA have similar spatial distribution, while obvious difference occurs at both high and low values.

Zhang, Yawen; Lu, Hui; Cai, Jun

2014-11-01

334

Ship-Track Clouds, Aerosol, and Ship Dynamic Effects; A Climate Perspective from Ship-Based Measurements  

SciTech Connect

Ship-track clouds are marine boundary layer clouds that form behind ocean ships and are observed from satellites in the visible and near infrared. Ship-track clouds provide a rare opportunity to connect aerosol cloud condensation nuclei (CCN) emissions and observable changes in marine stratiform clouds. A very small change in the reflectivity of these eastern Pacific and Atlantic clouds (about 4%) provides a climate feedback of similar magnitude to doubling CO{sub 2} (increasing cloud reflectivity corresponds to global cooling). The Department of Energy sponsored research from 1991 to 1995 to study ship-track clouds including two ocean-based experiments in the summers of 1991 and 1994. These experiments showed that ship-track cloud properties were often more complex those related to a reduction of droplet size with an increase in number associated with increasing CCN from the ship's plume. The clouds showed evidence of morphological changes more likely to be associated with cloud dynamic effects either initiated by the increased CCN or directly by the ship's heat output or turbulent air wake. The fact that marine stratiform clouds, that are susceptible to ship track formation, are starved for both CCN and convective turbulence complicates the separation of the two effects.

Porch, W.M.

1998-10-13

335

Long-term impacts of aerosols on vertical development of cloud and precipitation  

SciTech Connect

Aerosols alter cloud density and the radiative balance of the atmosphere. This leads to changes in cloud microphysics and atmospheric stability, which can either suppress or foster the development of clouds and precipitation. The net effect is largely unknown, but depends on meteorological conditions and aerosol properties. Here, we examine the long-term impact of aerosols on the vertical development of clouds and rainfall frequencies, using a 10-year dataset of aerosol, cloud and meteorological variables collected in the Southern Great Plains in the United States. We show that cloud-top height and thickness increase with aerosol concentration measured near the ground in mixed-phase clouds-which contain both liquid water and ice-that have a warm, low base. We attribute the effect, which is most significant in summer, to an aerosol-induced invigoration of upward winds. In contrast, we find no change in cloud-top height and precipitation with aerosol concentration in clouds with no ice or cool bases. We further show that precipitation frequency and rain rate are altered by aerosols. Rain increases with aerosol concentration in deep clouds that have a high liquid-water content, but declines in clouds that have a low liquid-water content. Simulations using a cloud-resolving model confirm these observations. Our findings provide unprecedented insights of the long-term net impacts of aerosols on clouds and precipitation.

Li Z.; Liu Y.; Niu, F.; Fan, J.; Rosenfeld, D.; Ding, Y.

2011-11-13

336

Large-scale document similarity computation based on cloud computing platform  

Microsoft Academic Search

Low efficiency existing in the current approaches for large scale document similarity computation, to make an improvement we pinpointed a new approach based on cloud computing platform in this paper. The approach carried out document similarity computation based on traditional vector model space as well as applied MapReduce computation model to realize the parallelization of distributed inverted index and similarity

Chaobo Hel; Yong Tang; Feiyi Tang; Atiao Yang

2011-01-01

337

Cloud-based systems for monitoring earthquakes and other environmental quantities  

NASA Astrophysics Data System (ADS)

There are many advantages to using a cloud-based system to record and analyze environmental quantities such as earthquakes, radiation, various gases, dust and meteorological parameters. These advantages include robustness and dynamic scalability, and also reduced costs. In this paper, we present our experiences over the last three years in developing a cloud-based earthquake monitoring system (the Community Seismic Network). This network consists of over 600 sensors (accelerometers) in the S. California region that send data directly to the Google App Engine where they are analyzed. The system is capable of handing many other types of sensor data and generating a situation-awareness analysis as a product. Other advantages to the cloud-based system are integration with other peer networks, and being able to deploy anywhere in the world without have to build addition computing infrastructure.

Clayton, R. W.; Olson, M.; Liu, A.; Chandy, M.; Bunn, J.; Guy, R.

2013-12-01

338

Accelerating and democratizing science through cloud-based services.  

SciTech Connect

Many businesses today save time and money, and increase their agility, by outsourcing mundane IT tasks to cloud providers. The author argues that similar methods can be used to overcome the complexities inherent in increasingly data-intensive, computational, and collaborative scientific research. He describes Globus Online, a system that he and his colleagues are developing to realize this vision. he scientific community today has unprecedented opportunities to effect transformational change in how individuals and teams engage in discovery. The driving force is a set of interrelated new capabilities that, when harnessed, can enable dramatic acceleration in the discovery process: greater availability of massive data, exponentially faster computers, ultra-high-speed networks, and deep interdisciplinary collaboration. The opportunity - and challenge - is to make these capabilities accessible not just to a few 'big science' projects but to every researcher at every level. Here, I argue that the key to seizing this opportunity is embracing software delivery methods that haven't been widely adopted in research, notably software as a service (SaaS) - a technology that forms an important part of what people refer to as the cloud. I also describe projects in the Computation Institute at the University of Chicago and Argonne National Laboratory that aim to realize this vision, focusing initially on data movement and management.

Foster, I. (CLS-CI); ( MCS)

2011-05-01

339

An intercomparison of radar-based liquid cloud microphysics retrievals and implications for model evaluation studies  

NASA Astrophysics Data System (ADS)

This paper presents a statistical comparison of three cloud retrieval products of the Atmospheric Radiation Measurement (ARM) program at the Southern Great Plains (SGP) site from 1998 to 2006: MICROBASE, University of Utah (UU), and University of North Dakota (UND) products. The probability density functions of the various cloud liquid water content (LWC) retrievals appear to be consistent with each other. While the mean MICROBASE and UU cloud LWC retrievals agree well in the middle of cloud, the discrepancy increases to about 0.03 gm-3 at cloud top and cloud base. Alarmingly large differences are found in the droplet effective radius (re) retrievals. The mean MICROBASE re is more than 6 ?m lower than the UU re, whereas the discrepancy is reduced to within 1 ?m if columns containing raining and/or mixed-phase layers are excluded from the comparison. A suite of stratified comparisons and retrieval experiments reveal that the LWC difference stems primarily from rain contamination, partitioning of total liquid later path (LWP) into warm and supercooled liquid, and the input cloud mask and LWP. The large discrepancy among the re retrievals is mainly due to rain contamination and the presence of mixed-phase layers. Since rain or ice particles are likely to dominate radar backscattering over cloud droplets, the large discrepancy found in this paper can be thought of as a physical limitation of single-frequency radar approaches. It is therefore suggested that data users should use the retrievals with caution when rain and/or mixed-phase layers are present in the column.

Huang, D.; Zhao, C.; Dunn, M.; Dong, X.; Mace, G. G.; Jensen, M. P.; Xie, S.; Liu, Y.

2012-06-01

340

An adaptive process-based cloud infrastructure for space situational awareness applications  

NASA Astrophysics Data System (ADS)

Space situational awareness (SSA) and defense space control capabilities are top priorities for groups that own or operate man-made spacecraft. Also, with the growing amount of space debris, there is an increase in demand for contextual understanding that necessitates the capability of collecting and processing a vast amount sensor data. Cloud computing, which features scalable and flexible storage and computing services, has been recognized as an ideal candidate that can meet the large data contextual challenges as needed by SSA. Cloud computing consists of physical service providers and middleware virtual machines together with infrastructure, platform, and software as service (IaaS, PaaS, SaaS) models. However, the typical Virtual Machine (VM) abstraction is on a per operating systems basis, which is at too low-level and limits the flexibility of a mission application architecture. In responding to this technical challenge, a novel adaptive process based cloud infrastructure for SSA applications is proposed in this paper. In addition, the details for the design rationale and a prototype is further examined. The SSA Cloud (SSAC) conceptual capability will potentially support space situation monitoring and tracking, object identification, and threat assessment. Lastly, the benefits of a more granular and flexible cloud computing resources allocation are illustrated for data processing and implementation considerations within a representative SSA system environment. We show that the container-based virtualization performs better than hypervisor-based virtualization technology in an SSA scenario.

Liu, Bingwei; Chen, Yu; Shen, Dan; Chen, Genshe; Pham, Khanh; Blasch, Erik; Rubin, Bruce

2014-06-01

341

Factors governing the total rainfall yield from continental convective clouds  

NASA Technical Reports Server (NTRS)

Several important factors that govern the total rainfall from continental convective clouds were investigated by tracking thousands of convective cells in Israel and South Africa. The rainfall volume yield (Rvol) of the individual cells that build convective rain systems has been shown to depend mainly on the cloud-top height. There is, however, considerable variability in this relationship. The following factors that influence the Rvol were parameterized and quantitatively analyzed: (1) cloud base temperature, (2)atmospheric instability, and (3) the extent of isolation of the cell. It is also shown that a strong low level forcing increases the duration of Rvol of clouds reaching the same vertical extent.

Rosenfeld, Daniel; Gagin, Abraham

1989-01-01

342

TPM: cloud-based tele-PTSD monitor using multi-dimensional information.  

PubMed

An automated system that can remotely and non-intrusively screen individuals at high risk for Post-Traumatic Stress Disorder (PTSD) and monitor their progress during treatment would be desired by many Veterans Affairs (VAs) as well as other PTSD treatment and research organizations. In this paper, we present an automated, cloud-based Tele-PTSD Monitor (TPM) system based on the fusion of multiple sources of information. The TPM system can be hosted in a cloud environment and accessed through landline or cell phones, or on the Internet through a web portal or mobile application (app). PMID:23400205

Xu, Roger; Mei, Gang; Zhang, Guangfan; Gao, Pan; Pepe, Aaron; Li, Jiang

2013-01-01

343

A cloud-based X73 ubiquitous mobile healthcare system: design and implementation.  

PubMed

Based on the user-centric paradigm for next generation networks, this paper describes a ubiquitous mobile healthcare (uHealth) system based on the ISO/IEEE 11073 personal health data (PHD) standards (X73) and cloud computing techniques. A number of design issues associated with the system implementation are outlined. The system includes a middleware on the user side, providing a plug-and-play environment for heterogeneous wireless sensors and mobile terminals utilizing different communication protocols and a distributed "big data" processing subsystem in the cloud. The design and implementation of this system are envisaged as an efficient solution for the next generation of uHealth systems. PMID:24737958

Ji, Zhanlin; Ganchev, Ivan; O'Droma, Máirtín; Zhang, Xin; Zhang, Xueji

2014-01-01

344

A Cloud-Based X73 Ubiquitous Mobile Healthcare System: Design and Implementation  

PubMed Central

Based on the user-centric paradigm for next generation networks, this paper describes a ubiquitous mobile healthcare (uHealth) system based on the ISO/IEEE 11073 personal health data (PHD) standards (X73) and cloud computing techniques. A number of design issues associated with the system implementation are outlined. The system includes a middleware on the user side, providing a plug-and-play environment for heterogeneous wireless sensors and mobile terminals utilizing different communication protocols and a distributed “big data” processing subsystem in the cloud. The design and implementation of this system are envisaged as an efficient solution for the next generation of uHealth systems. PMID:24737958

Ji, Zhanlin; O'Droma, Máirtín; Zhang, Xin; Zhang, Xueji

2014-01-01

345

Aerosol and Cloud Properties during the Cloud Cheju ABC Plume Asian Monsoon Experiment (CAPMEX) 2008: Linking between Ground-based and UAV Measurements  

Microsoft Academic Search

Cheju Atmospheric Brown Cloud (ABC) Plume-Monsoon Experiment (CAPMEX), comprehsensive ground-based measurements and a series of data-gathering flights by specially equipped autonomous unmanned aerial vehicles (AUAVs) for aerosol and cloud, had conducted at Jeju (formerly, Cheju), South Korea during August-September 2008, to improve our understanding of how the reduction of anthropogenic emissions in China (so-called ``great shutdown'' ) during and after

S. Kim; S. Yoon; M. Venkata Ramana; V. Ramanathan; H. Nguyen; M. Kim

2009-01-01

346

A Wing Pod-based Millimeter Wave Cloud Radar on HIAPER  

NASA Astrophysics Data System (ADS)

One of the attractive features of a millimeter wave radar system is its ability to detect micron-sized particles that constitute clouds with lower than 0.1 g m-3 liquid or ice water content. Scanning or vertically-pointing ground-based millimeter wavelength radars are used to study stratocumulus (Vali et al. 1998; Kollias and Albrecht 2000) and fair-weather cumulus (Kollias et al. 2001). Airborne millimeter wavelength radars have been used for atmospheric remote sensing since the early 1990s (Pazmany et al. 1995). Airborne millimeter wavelength radar systems, such as the University of Wyoming King Air Cloud Radar (WCR) and the NASA ER-2 Cloud Radar System (CRS), have added mobility to observe clouds in remote regions and over oceans. Scientific requirements of millimeter wavelength radar are mainly driven by climate and cloud initiation studies. Survey results from the cloud radar user community indicated a common preference for a narrow beam W-band radar with polarimetric and Doppler capabilities for airborne remote sensing of clouds. For detecting small amounts of liquid and ice, it is desired to have -30 dBZ sensitivity at a 10 km range. Additional desired capabilities included a second wavelength and/or dual-Doppler winds. Modern radar technology offers various options (e.g., dual-polarization and dual-wavelength). Even though a basic fixed beam Doppler radar system with a sensitivity of -30 dBZ at 10 km is capable of satisfying cloud detection requirements, the above-mentioned additional options, namely dual-wavelength, and dual-polarization, significantly extend the measurement capabilities to further reduce any uncertainty in radar-based retrievals of cloud properties. This paper describes a novel, airborne pod-based millimeter wave radar, preliminary radar measurements and corresponding derived scientific products. Since some of the primary engineering requirements of this millimeter wave radar are that it should be deployable on an airborne platform, occupy minimum cabin space and maximize scan coverage, a pod-based configuration was adopted. Currently, the radar system is capable of collecting observations between zenith and nadir in a fixed scanning mode. Measurements are corrected for aircraft attitude changes. The near-nadir and zenith pointing observations minimize the cross-track Doppler contamination in the radial velocity measurements. An extensive engineering monitoring mechanism is built into the recording system status such as temperature, pressure, various electronic components' status and receiver characteristics. Status parameters are used for real-time system stability estimates and correcting radar system parameters. The pod based radar system is mounted on a modified Gulfstream V aircraft, which is operated and maintained by the National Center for Atmospheric Research (NCAR) on behalf of the National Science Foundation (NSF). The aircraft is called the High-Performance Instrumented Airborne Platform for Environmental Research (HIAPER) (Laursen et al., 2006). It is also instrumented with high spectral resolution lidar (HSRL) and an array of in situ and remote sensors for atmospheric research. As part of the instrument suite for HIAPER, the NSF funded the development of the HIAPER Cloud Radar (HCR). The HCR is an airborne, millimeter-wavelength, dual-polarization, Doppler radar that serves the atmospheric science community by providing cloud remote sensing capabilities for the NSF/NCAR G-V (HIAPER) aircraft. An optimal radar configuration that is capable of maximizing the accuracy of both qualitative and quantitative estimated cloud microphysical and dynamical properties is the most attractive option to the research community. The Technical specifications of cloud radar are optimized for realizing the desired scientific performance for the pod-based configuration. The radar was both ground and flight tested and preliminary measurements of Doppler and polarization measurements were collected. HCR observed sensitivity as low as -37 dBZ at 1 km range and resolved linear depolarization ratio (LDR) si

Vivekanandan, Jothiram; Tsai, Peisang; Ellis, Scott; Loew, Eric; Lee, Wen-Chau; Emmett, Joanthan

2014-05-01

347

Evaluation of continuous ceilometer-based mixing layer heights and correlations with PM2.5 concentrations in Beijing  

NASA Astrophysics Data System (ADS)

Beijing air quality suffers from frequently occurring inversion layers. These inversion layers can last for several days and below these layers, pollution is accumulated. In the absence of inversions an urban boundary layer still exists delimiting the urban atmosphere from the free atmosphere. The height of this layer can potentially influence the urban atmospheric pollution. In both cases, particle concentration might change with height. A measurement campaign was performed to study those meteorological conditions, which are one of the causes for intensive air pollution in the region of Beijing during spring 2009. The mixing layer height (MLH) was studied by a ceilometer continuously. It was used to analyse the actual development of the height of inversion and boundary layers and the distribution of particles. Additionally, meteorological data from a radiosonde station are available. The measurements to study the vertical distribution of atmospheric layers in combination with particulate concentrations for specific times will be presented. The results of that campaign will be discussed.

Schäfer, Klaus; Wang, Yuesi; Münkel, Christoph; Emeis, Stefan; Xin, Jinyuan; Tang, Guiqian; Norra, Stefan; Schleicher, Nina; Vogt, Joachim; Suppan, Peter

2009-09-01

348

A cloud computing based platform for sleep behavior and chronic diseases collaborative research.  

PubMed

The objective of this study is to propose a Cloud Computing based platform for sleep behavior and chronic disease collaborative research. The platform consists of two main components: (1) a sensing bed sheet with textile sensors to automatically record patient's sleep behaviors and vital signs, and (2) a service-oriented cloud computing architecture (SOCCA) that provides a data repository and allows for sharing and analysis of collected data. Also, we describe our systematic approach to implementing the SOCCA. We believe that the new cloud-based platform can provide nurse and other health professional researchers located in differing geographic locations with a cost effective, flexible, secure and privacy-preserved research environment. PMID:24943526

Kuo, Mu-Hsing; Borycki, Elizabeth; Kushniruk, Andre; Huang, Yueh-Min; Hung, Shu-Hui

2014-01-01

349

Criteria for the evaluation of a cloud-based hospital information system outsourcing provider.  

PubMed

As cloud computing technology has proliferated rapidly worldwide, there has been a trend toward adopting cloud-based hospital information systems (CHISs). This study examines the critical criteria for selecting the CHISs outsourcing provider. The fuzzy Delphi method (FDM) is used to evaluate the primary indicator collected from 188 useable responses at a working hospital in Taiwan. Moreover, the fuzzy analytic hierarchy process (FAHP) is employed to calculate the weights of these criteria and establish a fuzzy multi-criteria model of CHISs outsourcing provider selection from 42 experts. The results indicate that the five most critical criteria related to CHISs outsourcing provider selection are (1) system function, (2) service quality, (3) integration, (4) professionalism, and (5) economics. This study may contribute to understanding how cloud-based hospital systems can reinforce content design and offer a way to compete in the field by developing more appropriate systems. PMID:22366976

Low, Chinyao; Hsueh Chen, Ya

2012-12-01

350

Physics-Based Visualization of Dense Natural Clouds. I. Three-Dimensional Discrete Ordinates Radiative Transfer  

NASA Astrophysics Data System (ADS)

A technique is developed to model radiative transfer in three-dimensional natural clouds with a standard discrete ordinates finite-element method modified to evaluate cell-surface-averaged radiances. A log-least-squares-based scale transformation is used to improve the discrete phase-function model. We handle dense media by assuming constant diffuse radiances over input faces to cubic cells, allowing analytical forms for transmittance factors. Transmission equations are combined with diffuse volumetric single-scattering calculations to support evaluations of cell energy balance. Energy not accounted for volumetrically is treated with surface-based effects. Results produced show accurate flux computations at over 30 optical depths per modeled cell. Comparisons with nonuniform cloud Monte Carlo calculations show less than 1% rms error and correlations greater than 0.999 for cases in which cloud-density fluctuations are resolved.

Tofsted, David H.; O'Brien, Sean G.

1998-11-01

351

Targeting and impacts of AgI cloud seeding based on rain chemical composition and cloud top phase characterization  

NASA Astrophysics Data System (ADS)

During four winters when cloud seeding took place, precipitation samples were collected at three stations in the catchment area of the Sea of Galilee (target stations) and in one station west of the seeding line (control station). Chemical analyses were carried out on more than 4000 rain samples in order to determine the major and trace metal compositions and enrichment factors of Ag (EF) with respect to Al, where Al is used as a tracer for natural dust. In addition, satellite images were analyzed to characterize the cloud phase and the temperature of the tops of the rain clouds using the EUMETSAT second generation geostationary satellite. Our results show that the seeding agent (AgI) arrives to the target stations, as indicated by significantly higher EFAg values of Ag there compared to the control station. Furthermore, we found higher EFAg values in precipitation samples from mixed-phase clouds compared to precipitation from warm or fully glaciated clouds. This difference was observed only at the target stations. Therefore, our results are consistent with the hypothesis that AgI contributes actively to precipitation formation processes in mixed-phase clouds, where ice content is controlled by ice nuclei (IN) concentration. This is in accordance with the conventional wisdom that AgI should be mostly active in such clouds, but not in clouds that are already naturally glaciated or in warm clouds, and it supports previous statistical studies which claimed that cloud seeding enhanced rainfall in Northern Israel.

Zipori, Assaf; Rosenfeld, Daniel; Shpund, Jacob; Steinberg, David M.; Erel, Yigal

2012-10-01

352

Validation of CERES-MODIS Arctic cloud properties using CloudSat/CALIPSO and ARM NSA observations  

NASA Astrophysics Data System (ADS)

The traditional passive satellite studies of cloud properties in the Arctic are often affected by the complex surface features present across the region. Nominal visual and thermal contrast exists between Arctic clouds and the snow- and ice-covered surfaces beneath them, which can lead to difficulties in satellite retrievals of cloud properties. However, the addition of active sensors to the A-Train constellation of satellites has increased the availability of validation sources for cloud properties derived from passive sensors in the data-sparse high-latitude regions. In this study, Arctic cloud fraction and cloud heights derived from the NASA CERES team (CERES-MODIS) have been compared with CloudSat/CALIPSO and DOE ARM NSA radar-lidar observations over Barrow, AK, for the two-year period from 2007 to 2008. An Arctic-wide comparison of cloud fraction and height between CERES-MODIS and CloudSat/CALIPSO was then conducted for the same time period. The CERES-MODIS cloud properties, which include cloud fraction and cloud effective heights, were retrieved using the 4-channel VISST (Visible Infrared Solar-Infrared Split-window Technique) [Minnis et al.,1995]. CloudSat/CALIPSO cloud fraction and cloud-base and -top heights were from version RelB1 data products determined by both the 94 GHz radar onboard CloudSat and the lidar on CALIPSO with a vertical resolution of 30 m below 8.2 km and 60 m above. To match the surface and satellite observations/retrievals, the ARM surface observations were averaged into 3-hour intervals centered at the time of the satellite overpass, while satellite observations were averaged within a 3°x3° grid box centered on the Barrow site. The preliminary results have shown that all observed CFs have peaks during April-May and September-October, and dips during winter months (January-February) and summer months (June-July) during the study period of 2007-2008. ARM radar-lidar and CloudSat/CALIPSO show generally good agreement in CF (0.79 vs. 0.74), while CERES-MODIS derived values are much lower (0.60). CERES-MODIS derived cloud effective height (2.7 km) falls between the CloudSat/CALIPSO derived cloud base (0.6 km) and top (6.4 km) and the ARM ceilometers and MMCR derived cloud base (0.9 km) and radar derived cloud top (5.8 km). When extended to the entire Arctic, although the CERES-MODIS and Cloudsat/CALIPSO derived annual mean CFs agree within a few percents, there are significant differences over several regions, and the maximum cloud heights derived from CloudSat/CALIPSO (13.4 km) and CERES-MODIS (10.7 km) show the largest disagreement during early spring.

Giannecchini, K.; Dong, X.; Xi, B.; Minnis, P.; Kato, S.

2011-12-01

353

mPano: cloud-based mobile panorama view from single picture  

NASA Astrophysics Data System (ADS)

Panorama view provides people an informative and natural user experience to represent the whole scene. The advances on mobile augmented reality, mobile-cloud computing, and mobile internet can enable panorama view on mobile phone with new functionalities, such as anytime anywhere query where a landmark picture is and what the whole scene looks like. To generate and explore panorama view on mobile devices faces significant challenges due to the limitations of computing capacity, battery life, and memory size of mobile phones, as well as the bandwidth of mobile Internet connection. To address the challenges, this paper presents a novel cloud-based mobile panorama view system that can generate and view panorama-view on mobile devices from a single picture, namely "Pano". In our system, first, we propose a novel iterative multi-modal image retrieval (IMIR) approach to get spatially adjacent images using both tag and content information from the single picture. Second, we propose a cloud-based parallel server synthing approach to generate panorama view in cloud, against today's local-client synthing approach that is almost impossible for mobile phones. Third, we propose predictive-cache solution to reduce latency of image delivery from cloud server to the mobile client. We have built a real mobile panorama view system and perform experiments. The experimental results demonstrated the effectiveness of our system and the proposed key component technologies, especially for landmark images.

Li, Hongzhi; Zhu, Wenwu

2013-09-01

354

Wide-angle airborne laser range data analysis for relative height determination of ground-based benchmarks  

NASA Astrophysics Data System (ADS)

A wide-angle airborne laser ranging system has been developed for the determination of relative heights of ground-based benchmarks in regional-scale networks (typically 100 laser reflectors spread over 100 km2). A first prototype demonstrated a 1-2 mm accuracy in radial distance measurement in a ground-based experiment in 1995. The first aircraft experiment was conducted in 1998, over a small area (1 km2) equipped with a network of 64 benchmarks. The instrument was modified before that experiment, in order to minimize echo superimposition due to the high density of benchmarks. New data processing algorithms have been developed, for the deconvolution of strongly overlapped echoes and a high a priori uncertainty in the aircraft flight path, and for the estimation of benchmark coordinates. A special methodology has been developed for the parameterization of these algorithms and of outlier detection tests. From a total of 22104 pseudo-range measurements, that have been acquired from two flights composed of 30 legs each, only 32103 remain after outlier detection. A positioning accuracy of 1.5 cm in the vertical coordinate (2.1 cm in the difference between the two flights) has been achieved. It is shown that the errors are normally distributed, with a nearly zero mean, and are consistent with the a posteriori uncertainty. It is also shown that the accuracy is limited mainly by the sensitivity of the photodetector used for this experiment (due to reduced response time). Another limiting factor is the effect of aircraft attitude changes during the measurements, which produces additional uncertainties in absolute distance measurements. It is planned to test new photodetectors with high internal gains. These should provide, in future experiments with smaller benchmark density, an improvement in signal-to-noise ratio of a factor of 5-10, leading to sub-centimeter vertical positioning accuracy.

Bock, O.; Thom, C.

2002-07-01

355

A multi-sensor plume height analysis of the 2009 Redoubt eruption  

NASA Astrophysics Data System (ADS)

During an explosive volcanic eruption, accurately determining the height of a volcanic plume or cloud is essential to accurately forecast its motion because volcanic ash transport and dispersion models require the initial plume height as an input parameter. The direct use of satellite infrared temperatures for height determination, one of the most commonly employed methods at the Alaska Volcano Observatory, often does not yield unique solutions for height. This result is documented here for the 2009 eruption of Redoubt Volcano. Satellite temperature heights consistently underestimated the height of ash plumes in comparison to other methods such as ground-based radar and Multi-angle Imaging SpectroRadiometer (MISR) stereo heights. For ash plumes below the tropopause, increasing transparency of a plume begins to affect the accuracy of simple temperature height retrievals soon after eruption. With decreasing opacity, plume temperature heights become increasingly inaccurate. Comparison with dispersion models and aircraft gas flight data confirms that radar and MISR stereo heights are more accurate than basic satellite temperature heights. Even in the cases in which satellite temperature results appeared to be relatively accurate (e.g., for plumes below the tropopause), a mixed signal of plume and ground radiation still presented an issue for almost every event studied. This was true regardless of the fact that a band differencing method was used to remove presumably translucent pixels. The data presented here make a strong case for the use of data fusion in volcano monitoring, as there is a need to confirm satellite temperature heights with other height data. If only basic satellite temperature heights are available for a given eruption, then these heights must be considered with a significant margin of error.

Ekstrand, Angela L.; Webley, Peter W.; Garay, Michael J.; Dehn, Jonathan; Prakash, Anupma; Nelson, David L.; Dean, Kenneson G.; Steensen, Torge

2013-06-01

356

All Your Browser-saved Passwords Could Belong to Us: a Security Analysis and a Cloud-based New Design  

E-print Network

--Security. Keywords Web browser, password manager, security, phishing, cloud 1. INTRODUCTION Text-based passwordsAll Your Browser-saved Passwords Could Belong to Us: a Security Analysis and a Cloud-based New Design Rui Zhao University of Colorado Colorado Springs Department of Computer Science Colorado Springs

Yue, Chuan

357

Cloud-based Content Distribution on a Budget Boston University, Computer Science Technical Report BUCS-TR-2010-022  

E-print Network

signal that gauges the real-time health of the swarm. Our extensive evaluation of CYCLOPS in a variety costs, especially when demand is highly dynamic, or unpredictable. For many cloud-based ICT solutionsCloud-based Content Distribution on a Budget Boston University, Computer Science Technical Report

358

Determining Boundary-Layer Height from Aircraft Measurements  

NASA Astrophysics Data System (ADS)

The height of the atmospheric boundary layer (ABL) is an important variable in both observational studies and model simulations. The most commonly used measurement for obtaining ABL height is a rawinsonde profile. Mesoscale or regional scale models use a bulk Richardson number based on profiles of the forecast variables. Here we evaluate the limitations of several frequently-used approaches for defining ABL height from a single profile, and identify the optimal threshold value for each method if profiles are the only available measurements. Aircraft measurements from five field projects are used, representing a variety of ABL conditions including stable, convective, and cloud-topped boundary layers over different underlying surfaces. ABL heights detected from these methods were validated against the `true' value determined from aircraft soundings, where ABL height is defined as the top of the layer with significant turbulence. A detection rate was defined to denote how often the ABL height was correctly diagnosed with a particular method. The results suggest that the temperature gradient method provides the most reasonable estimates, although the detection rate and suitable detection criteria vary for different types of ABL. The Richardson number method, on the other hand, is in most cases inadequate or inferior to the other methods that were tried. The optimal range of the detection criteria is given for all ABL types examined in this study.

Dai, C.; Wang, Q.; Kalogiros, J. A.; Lenschow, D. H.; Gao, Z.; Zhou, M.

2014-09-01

359

QoS-aware health monitoring system using cloud-based WBANs.  

PubMed

Wireless Body Area Networks (WBANs) are amongst the best options for remote health monitoring. However, as standalone systems WBANs have many limitations due to the large amount of processed data, mobility of monitored users, and the network coverage area. Integrating WBANs with cloud computing provides effective solutions to these problems and promotes the performance of WBANs based systems. Accordingly, in this paper we propose a cloud-based real-time remote health monitoring system for tracking the health status of non-hospitalized patients while practicing their daily activities. Compared with existing cloud-based WBAN frameworks, we divide the cloud into local one, that includes the monitored users and local medical staff, and a global one that includes the outer world. The performance of the proposed framework is optimized by reducing congestion, interference, and data delivery delay while supporting users' mobility. Several novel techniques and algorithms are proposed to accomplish our objective. First, the concept of data classification and aggregation is utilized to avoid clogging the network with unnecessary data traffic. Second, a dynamic channel assignment policy is developed to distribute the WBANs associated with the users on the available frequency channels to manage interference. Third, a delay-aware routing metric is proposed to be used by the local cloud in its multi-hop communication to speed up the reporting process of the health-related data. Fourth, the delay-aware metric is further utilized by the association protocols used by the WBANs to connect with the local cloud. Finally, the system with all the proposed techniques and algorithms is evaluated using extensive ns-2 simulations. The simulation results show superior performance of the proposed architecture in optimizing the end-to-end delay, handling the increased interference levels, maximizing the network capacity, and tracking user's mobility. PMID:25123456

Almashaqbeh, Ghada; Hayajneh, Thaier; Vasilakos, Athanasios V; Mohd, Bassam J

2014-10-01

360

The interdependence of continental warm cloud properties derived from unexploited solar background signal in ground-based lidar measurements  

NASA Astrophysics Data System (ADS)

We have extensively analysed the interdependence between cloud optical depth, droplet effective radius, liquid water path (LWP) and geometric thickness for stratiform warm clouds using ground-based observations. In particular, this analysis uses cloud optical depths retrieved from untapped solar background signal that is previously unwanted and needs to be removed in most lidar applications. Combining these new optical depth retrievals with radar and microwave observations at the Atmospheric Radiation Measurement (ARM) Climate Research Facility in Oklahoma during 2005-2007, we have found that LWP and geometric thickness increase and follow a power-law relationship with cloud optical depth regardless of the presence of drizzle; LWP and geometric thickness in drizzling clouds can be generally 20-40% and at least 10% higher than those in non-drizzling clouds, respectively. In contrast, droplet effective radius shows a negative correlation with optical depth in drizzling clouds, while it increases with optical depth and reaches an asymptote of 10 ?m in non-drizzling clouds. This asymptotic behaviour in non-drizzling clouds is found in both droplet effective radius and optical depth, making it possible to use simple thresholds of optical depth, droplet size, or a combination of these two variables for drizzle delineation. This paper demonstrates a new way to enhance ground-based cloud observations and drizzle delineations using existing lidar networks.

Chiu, J. C.; Holmes, J. A.; Hogan, R. J.; O'Connor, E. J.

2014-04-01

361

The interdependence of continental warm cloud properties derived from unexploited solar background signals in ground-based lidar measurements  

NASA Astrophysics Data System (ADS)

We have extensively analysed the interdependence between cloud optical depth, droplet effective radius, liquid water path (LWP) and geometric thickness for stratiform warm clouds using ground-based observations. In particular, this analysis uses cloud optical depths retrieved from untapped solar background signals that are previously unwanted and need to be removed in most lidar applications. Combining these new optical depth retrievals with radar and microwave observations at the Atmospheric Radiation Measurement (ARM) Climate Research Facility in Oklahoma during 2005-2007, we have found that LWP and geometric thickness increase and follow a power-law relationship with cloud optical depth regardless of the presence of drizzle; LWP and geometric thickness in drizzling clouds can be generally 20-40% and at least 10% higher than those in non-drizzling clouds, respectively. In contrast, droplet effective radius shows a negative correlation with optical depth in drizzling clouds and a positive correlation in non-drizzling clouds, where, for large optical depths, it asymptotes to 10 ?m. This asymptotic behaviour in non-drizzling clouds is found in both the droplet effective radius and optical depth, making it possible to use simple thresholds of optical depth, droplet size, or a combination of these two variables for drizzle delineation. This paper demonstrates a new way to enhance ground-based cloud observations and drizzle delineations using existing lidar networks.

Chiu, J. C.; Holmes, J. A.; Hogan, R. J.; O'Connor, E. J.

2014-08-01

362

The cloud radiative effect on the atmospheric energy budget and global mean precipitation  

NASA Astrophysics Data System (ADS)

This study seeks to explain the effects of cloud on changes in atmospheric radiative absorption that largely balance changes in global mean precipitation under climate change. The partial radiative perturbations (PRPs) due to changes in cloud and due to the effects of the pre-existing climatological cloud distribution on non-cloud changes, known as "cloud masking", are calculated when atmospheric CO2 concentration is doubled for the HadSM3 and MIROC models and for a large ensemble of parameter perturbed models based on HadSM3. Because the effect of cloud on changes in atmospheric shortwave absorption is almost negligible, longwave fluxes are analysed alone. We find that the net effects of cloud masking and cloud PRP on atmospheric absorption are both substantial. For the tropics, our results are reviewed in light of hypotheses put forward to explain cloud and radiative flux changes. We find that the major effects of clouds on radiation change are linked to known physical processes that are quite consistently simulated by models. Cloud top height changes are quite well described by the fixed anvil temperature hypothesis of Hartmann and Larson; cloud base heights change little, remaining near the same pressure. Changes in cloud geographical location and cloud amount are significant, but play a smaller role in driving radiative flux changes. Finally, because clouds are a large source of modelling uncertainty, we consider whether resolving errors in cloud simulation could reconcile modelled global mean precipitation trends of about 1-3 %{K}^{-1} with some estimates of observed trends of 7 %{K}^{-1} or more. This would require the radiative effect of clouds to change from one that increases atmospheric radiative absorption by about 0.5 {Wm}^{-2} {K}^{-1} to one that decreases it by -3.5 {Wm}^{-2} {K}^{-1} . Based on our results, this seems difficult to achieve within our current rationale for the tropics at least.

Lambert, F. Hugo; Webb, Mark J.; Yoshimori, Masakazu; Yokohata, Tokuta

2014-05-01

363

Geopot: a Cloud-based geolocation data service for mobile applications  

Microsoft Academic Search

We propose a novel Cloud-based geolocation data service system, termed ‘Geopot’, for location-based mobile applications. The exponentially growing number of users of location-based mobile applications demand a data service that can easily be deployed and is scalable against a large volume of accesses from mobile devices across the world. The purpose of our work is to construct a scalable spatial

DongWoo Lee; Steve H. L. Liang

2011-01-01

364

Tackling the Loss of Control: Standards-based Conjoint Management of Security Requirements for Cloud Services  

E-print Network

Tackling the Loss of Control: Standards-based Conjoint Management of Security Requirements manage security requirements for a Cloud service following the ISO 27001 standard for infor- mation security management. We have developed a security management platform that provides tool support

Schneider, Jean-Guy

365

Development of Cloud Computing Based Scheduling System Using Optimized Layout Method for Manufacturing Quality  

Microsoft Academic Search

In the paper, to develop a cloud computing based scheduling system, using optimized layout method is proposed. In order to develop a scheduling system considering manufacturing quality, it is necessary to immediately build up different layout mode of production lines. The factors of manufacturing quality are product, equipment, material and human. It makes high cost for scheduling the flexible manufacturing

Chung-Chi Huang; Chung-Lin Huang

2012-01-01

366

An E-learning Ecosystem Based on Cloud Computing Infrastructure Bo Dong1, 2  

E-print Network

An E-learning Ecosystem Based on Cloud Computing Infrastructure Bo Dong1, 2 , Qinghua Zheng1, 2 that an e-learning ecosystem is the next generation e- learning. However, the current models of e-learning ecosystems lack the support of underlying infrastructures, which can dynamically allocate the required

Li, Haifei

367

A Secure Cloud-based NFC Mobile Payment Protocol Pardis Pourghomi.1  

E-print Network

. Gheorghita Ghinea1 Abstract Near Field Communication (NFC) is one the most recent technologies in the area1 A Secure Cloud-based NFC Mobile Payment Protocol Pardis Pourghomi.1 Muhammad Qasim Saeed2 of application development and service delivery via mobile phone. NFC enables the mobile phone to act

368

Robust Message-Privacy Preserving Image Copy Detection for Cloud-based Systems  

E-print Network

that in turn are used to encrypt the source image and serve as a robust hash that can be queried for contentRobust Message-Privacy Preserving Image Copy Detection for Cloud-based Systems M. Diephuis, S verification, image-content identification, copy-detection, privacy and authentication perfectly. Additionally

Genève, Université de

369

A dynamic load balancing strategy for cloud computing platform based on exponential smoothing forecast  

Microsoft Academic Search

Because of the elastic service capability of cloud computing platform , more and more applications are moved here, which makes efficient load balancing into a bottleneck.Considering the unique features of long-connectivity applications which are increasingly popular nowadays, an improved algorithm is proposed based on the weighted least connection algorithm. In the new algorithm , load and processing power are quantified,

Xiaona Ren; Rongheng Lin; Hua Zou

2011-01-01

370

Using a Cloud-Based Computing Environment to Support Teacher Training on Common Core Implementation  

ERIC Educational Resources Information Center

A cloud-based computing environment, Google Apps for Education (GAFE), has provided the Anaheim City School District (ACSD) a comprehensive and collaborative avenue for creating, sharing, and editing documents, calendars, and social networking communities. With this environment, teachers and district staff at ACSD are able to utilize the deep…

Robertson, Cory

2013-01-01

371

Exploring Architecture Options for a Federated, Cloud-based System Biology Knowledgebase  

SciTech Connect

This paper evaluates various cloud computing technologies and resources for building a system biology knowledge base system. This system will host a huge amount of data and contain a flexible sets of workflows to operate on these data. It will enable system biologist to share their data and algorithms to allow research results to be reproduced, shared, and reused across the system biology community.

Gorton, Ian; Liu, Yan; Yin, Jian

2010-12-02

372

Architecture of Web-EDA system based on Cloud computing and application for project management of IC design  

Microsoft Academic Search

Cloud computing is usually defined to deliver infrastructure, platform and software as services, which is available as a pay-as-you-go model for users. A paradigm of Cloud computing for EDA service is presented in this paper, and a hierarchical architecture of Web-EDA system implemented with Cloud computing is described in detail. Based on this proposed system structure, we developed a prototype

Xiaopeng Lin; Yiyang Li; Huaiyu Dai; Donghui Guo

2010-01-01

373

Cloud point extraction of aloe anthraquinones based on non-ionic surfactant aqueous two-phase system  

Microsoft Academic Search

Non-ionic surfactant-based aqueous two-phase system had been investigated to extract aloe anthraquinones. It had the advantage of using a single auxiliary chemical to induce phase separation above cloud point at a low concentration. Non-ionic surfactant Triton X-114 was chosen for its excellent phase-separating ability and low cloud point. The main factors affecting the cloud point extraction were discussed such as

Zhi-Jian Tan; Fen-Fang Li; Jian-Min Xing

2011-01-01

374

Cloud point extraction of aloe anthraquinones based on non-ionic surfactant aqueous two-phase system  

Microsoft Academic Search

Non-ionic surfactant-based aqueous two-phase system had been investigated to extract aloe anthraquinones. It had the advantage of using a single auxiliary chemical to induce phase separation above cloud point at a low concentration. Non-ionic surfactant Triton X-114 was chosen for its excellent phase-separating ability and low cloud point. The main factors affecting the cloud point extraction were discussed such as

Zhi-Jian Tan; Fen-Fang Li; Jian-Min Xing

2012-01-01

375

Cloud Property Retrieval Products for Graciosa Island, Azores  

SciTech Connect

The motivation for developing this product was to use the Dong et al. 1998 method to retrieve cloud microphysical properties, such as cloud droplet effective radius, cloud droplets number concentration, and optical thickness. These retrieved properties have been used to validate the satellite retrieval, and evaluate the climate simulations and reanalyses. We had been using this method to retrieve cloud microphysical properties over ARM SGP and NSA sites. We also modified the method for the AMF at Shouxian, China and some IOPs, e.g. ARM IOP at SGP in March, 2000. The ARSCL data from ARM data archive over the SGP and NSA have been used to determine the cloud boundary and cloud phase. For these ARM permanent sites, the ARSCL data was developed based on MMCR measurements, however, there were no data available at the Azores field campaign. We followed the steps to generate this derived product and also include the MPLCMASK cloud retrievals to determine the most accurate cloud boundaries, including the thin cirrus clouds that WACR may under-detect. We use these as input to retrieve the cloud microphysical properties. Due to the different temporal resolutions of the derived cloud boundary heights product and the cloud properties product, we submit them as two separate netcdf files.

Dong, Xiquan

2014-05-05

376

Cloud Property Retrieval Products for Graciosa Island, Azores  

DOE Data Explorer

The motivation for developing this product was to use the Dong et al. 1998 method to retrieve cloud microphysical properties, such as cloud droplet effective radius, cloud droplets number concentration, and optical thickness. These retrieved properties have been used to validate the satellite retrieval, and evaluate the climate simulations and reanalyses. We had been using this method to retrieve cloud microphysical properties over ARM SGP and NSA sites. We also modified the method for the AMF at Shouxian, China and some IOPs, e.g. ARM IOP at SGP in March, 2000. The ARSCL data from ARM data archive over the SGP and NSA have been used to determine the cloud boundary and cloud phase. For these ARM permanent sites, the ARSCL data was developed based on MMCR measurements, however, there were no data available at the Azores field campaign. We followed the steps to generate this derived product and also include the MPLCMASK cloud retrievals to determine the most accurate cloud boundaries, including the thin cirrus clouds that WACR may under-detect. We use these as input to retrieve the cloud microphysical properties. Due to the different temporal resolutions of the derived cloud boundary heights product and the cloud properties product, we submit them as two separate netcdf files.

Dong, Xiquan

377

Unawareness of weight and height - the effect on self-reported prevalence of overweight in a population-based study  

Microsoft Academic Search

Objective  Self-reported height and weight are commonly used to estimate body mass index. The present study aims to identify the characteristics\\u000a of participants who reported not to know their height or weight and to evaluate the consequence of these missing data on the\\u000a estimates of the prevalence of body mass index categories.\\u000a \\u000a \\u000a \\u000a Design and Participants  We evaluated 1492 adults, aged 18–92 years,

E. Ramos; C. Lopes; A. Oliveira; H. Barros

2009-01-01

378

The Evaluation of CloudSat and CALIPSO Ice Microphysical Products Using Ground-Based Cloud Radar and Lidar Observations  

E-print Network

, the statistical relationship used to produce ice water content from extinction and air temperature obtained ice clouds, but that the temperature dependence of the statistical relationship used should) ABSTRACT In this paper, the statistical properties of tropical ice clouds (ice water content, visible

Protat, Alain

379

GPGPU-based parallel processing of massive LiDAR point cloud  

NASA Astrophysics Data System (ADS)

Processing the massive LiDAR point cloud is a time consuming process due to the magnitude of the data involved and the highly computational iterative nature of the algorithms. In particular, many current and future applications of LiDAR require real- or near-real-time processing capabilities. Relevant examples include environmental studies, military applications, tracking and monitoring of hazards. Recent advances in Graphics Processing Units (GPUs) open a new era of General-Purpose Processing on Graphics Processing Units (GPGPU). In this paper, we seek to harness the computing power available on contemporary Graphic Processing Units (GPUs), to accelerate the processing of massive LiDAR point cloud. We propose a CUDA-based method capable of accelerating processing of massive LiDAR point cloud on the CUDA-enabled GPU. Our experimental results showed that we are able to significantly reduce processing time of constructing TIN from LiDAR point cloud with GPGPU based parallel processing implementation, in comparison with the current state-of-the-art CPU-based algorithms.

Zeng, Xun; He, Wei

2009-10-01

380

Toward Image-Based Three-Dimensional Reconstruction from Cubesats: Impacts of Spatial Resolution and SNR on Point Cloud Quality  

NASA Astrophysics Data System (ADS)

The adoption of cube-satellites (cubesats) by the space community has drastically lowered the cost of access to space and reduced the development lifecycle from the hundreds of millions of dollars spent on traditional decade-long programs. Rapid deployment and low cost are attractive features of cubesat-based imaging that are conducive to applications such as disaster response and monitoring. One proposed application is 3D surface modeling through a high revisit rate constellation of cubesat imagers. This work begins with the characterization of an existing design for a cubesat imager based on ground sampled distance (GSD), signal-to-noise ratio (SNR), and smear. From this characterization, an existing 3D workflow is applied to datasets that have been degraded within the regime of spatial resolutions and signal-to-noise ratios anticipated for the cubesat imager. The fidelity of resulting point clouds are assessed locally for both an urban and a natural scene. The height of a building and normals to its surfaces are calculated from the urban scene, while quarry depth estimates and rough volume estimates of a pile of rocks are produced from the natural scene. Though the reconstructed scene geometry and completeness of the scene suffer noticeably from the degraded imagery, results indicate that useful information can still be extracted using some of these techniques up to a simulated GSD of 2 meters.

Stoddard, Jordyn

381

Observer Interface Analysis for Standardization to a Cloud Based Real-Time Space Situational Awareness (SSA)  

NASA Astrophysics Data System (ADS)

The interface analysis from an observer of space objects makes a standard necessary. This standardized dataset serves as input for a cloud based service, which aimed for a near real-time Space Situational Awareness (SSA) system. The system contains all advantages of a cloud based solution, like redundancy, scalability and an easy way to distribute information. For the standard based on the interface analysis of the observer, the information can be separated in three parts. One part is the information about the observer e.g. a ground station. The next part is the information about the sensors that are used by the observer. And the last part is the data from the detected object. Backbone of the SSA System is the cloud based service which includes the consistency check for the observed objects, a database for the objects, the algorithms and analysis as well as the visualization of the results. This paper also provides an approximation of the needed computational power, data storage and a financial approach to deliver this service to a broad community. In this context cloud means, neither the user nor the observer has to think about the infrastructure of the calculation environment. The decision if the IT-infrastructure will be built by a conglomerate of different nations or rented on the marked should be based on an efficiency analysis. Also combinations are possible like starting on a rented cloud and then go to a private cloud owned by the government. One of the advantages of a cloud solution is the scalability. There are about 3000 satellites in space, 900 of them are active, and in total there are about ~17.000 detected space objects orbiting earth. But for the computation it is not a N(active) to N problem it is more N(active) to N(apo peri) quantity of N(all). Instead of 15.3 million possible collisions to calculate a computation of only approx. 2.3 million possible collisions must be done. In general, this Space Situational Awareness System can be used as a tool for satellite system owner for collision avoidance.

Eilers, J.

2013-09-01

382

Decadal Variability of West Coast Marine Stratus Clouds  

NASA Astrophysics Data System (ADS)

Low frequency variability of West Coast summertime marine stratus clouds are investigated using six decades of observations at several coastal airport locations. The magnitude and direction of long-term trends in summertime marine stratus occurrence along the California coast depends strongly on the cloud base height threshold used to distinguish low clouds from higher clouds. In this study, marine stratus clouds are defined as having cloud base at or below 1000 meters. Using this threshold, a decreasing trend in marine stratus cloud frequency was found for Southern California during the 1950-2012 period. No significant trends were found in Northern California. When averaged over the summer season, the cloud data reveal that coastal stratus has substantial variation on multi-year time scales with typical changes of 10-15% from year to year and 5-7% from decade to decade. Low stratus cloud cover varies over long distances with coherent anomalies that extend from southern California to Oregon. The most important correlated modes of SST with cloud cover anomalies, via a canonical correlation analysis contains both local and remote SST linkages. The first mode is correlated with the PDO and also to Pacific atmospheric circulation patterns and coastal upwelling. There is also a linkage to sea surface temperature anomalies in the low latitude Pacific, suggesting that tropical-extratropical interactions may be involved in driving West Coast cloud cover.

Iacobellis, S.; Schwartz, R. E.; Gershunov, A.; Cayan, D. R.; Williams, P.

2013-12-01

383

LIVAS: a 3-D multi-wavelength aerosol/cloud climatology based on CALIPSO and EARLINET  

NASA Astrophysics Data System (ADS)

We present LIVAS, a 3-dimentional multi-wavelength global aerosol and cloud optical climatology, optimized to be used for future space-based lidar end-to-end simulations of realistic atmospheric scenarios as well as retrieval algorithm testing activities. LIVAS database provides averaged profiles of aerosol optical properties for the potential space-borne laser operating wavelengths of 355, 532, 1064, 1570 and 2050 nm and of cloud optical properties at the wavelength of 532 nm. The global climatology is based on CALIPSO observations at 532 and 1064 nm and on aerosol-type-dependent spectral conversion factors for backscatter and extinction, derived from EARLINET ground-based measurements for the UV and scattering calculations for the IR wavelengths, using a combination of input data from AERONET, suitable aerosol models and recent literature. The required spectral conversion factors are calculated for each of the CALIPSO aerosol types and are applied to CALIPSO extinction and backscatter data correspondingly to the aerosol type retrieved by the CALIPSO aerosol classification scheme. A cloud climatology based on CALIPSO measurements at 532 nm is also provided, neglecting wavelength conversion due to approximately neutral scattering behavior of clouds along the spectral range of LIVAS. Averages of particle linear depolarization ratio profiles at 532 nm are provided as well. Finally, vertical distributions for a set of selected scenes of specific atmospheric phenomena (e.g., dust outbreaks, volcanic eruptions, wild fires, polar stratospheric clouds) are analyzed and spectrally converted so as to be used as case studies for space-borne lidar performance assessments. The final global climatology includes 4-year (1 January 2008-31 December 2011) time-averaged CALIPSO data on a uniform grid of 1×1 degree with the original high vertical resolution of CALIPSO in order to ensure realistic simulations of the atmospheric variability in lidar end-to-end simulations.

Amiridis, V.; Marinou, E.; Tsekeri, A.; Wandinger, U.; Schwarz, A.; Giannakaki, E.; Mamouri, R.; Kokkalis, P.; Binietoglou, I.; Solomos, S.; Herekakis, T.; Kazadzis, S.; Gerasopoulos, E.; Balis, D.; Papayannis, A.; Kontoes, C.; Kourtidis, K.; Papagiannopoulos, N.; Mona, L.; Pappalardo, G.; Le Rille, O.; Ansmann, A.

2015-01-01

384

Near-global survey of effective droplet radii in liquid water clouds using ISCCP data  

NASA Technical Reports Server (NTRS)

A global survey of cloud particle size variations can provide crucial constraints on how cloud processes determine cloud liquid water contents and their variation with temperature, and further, may indicate the magnitude of aerosol effects on clouds. A method, based on a complete radiative transfer model for Advanced Very High Resolution Radiometer (AVHRR)-measured radiances, is described for retrieving cloud particle radii in liquid water clouds from satellite data currently available from the International Satellite Cloud Climatology Project. Results of sensitivity tests and validation studies provide error estimates. AVHRR data from NOAA-9 and NOAA-10 have been analyzed for January, April, July and October in 1987 and 1988. The results of this first survey reveal systematic continental and maritime differences and hemispheric contrasts that are indicative of the effects of associated aerosol concentration differences: cloud droplet radii in continental water clouds are about 2-3 micrometers smaller than in marine clouds, and droplet radii are about 1 micrometer smaller in marine clouds of the Northern Hemisphere than in the Southern Hemisphere. The height dependencies of cloud droplet radii in continental and marine clouds are also consistent with differences in the vertical profiles of aerosol concentration. Significant seasonal and diurnal variations of effective droplet radii are also observed, particularly at lower latitudes. Variations of the relationship between cloud optical thickness and droplet radii may indicate variations in cloud microphysical regimes.

Han, Qingyan; Rossow, William B.; Lacis, Andrew B.

1994-01-01

385

Aerosol and Cloud Properties during the Cloud Cheju ABC Plume -Asian Monsoon Experiment (CAPMEX) 2008: Linking between Ground-based and UAV Measurements  

NASA Astrophysics Data System (ADS)

Cheju Atmospheric Brown Cloud (ABC) Plume-Monsoon Experiment (CAPMEX), comprehsensive ground-based measurements and a series of data-gathering flights by specially equipped autonomous unmanned aerial vehicles (AUAVs) for aerosol and cloud, had conducted at Jeju (formerly, Cheju), South Korea during August-September 2008, to improve our understanding of how the reduction of anthropogenic emissions in China (so-called “great shutdown” ) during and after the Summer Beijing Olympic Games 2008 effcts on the air quliaty and radiation budgets and how atmospheric brown clouds (ABCs) influences solar radiation budget off Asian continent. Large numbers of in-situ and remote sensing instruments at the Gosan ABC observatory and miniaturized instruments on the aircraft measure a range of properties such as the quantity of soot, size-segregated aerosol particle numbers, total particle numbers, size-segregated cloud droplet numbers (only AUAV), aerosol scattering properties (only ground), aerosol vertical distribution, column-integrated aerosol properties, and meteorological variables. By integrating ground-level and high-elevation AUAV measurements with NASA-satellite observations (e.g., MODIS, CALIPSO), we investigate the long range transport of aerosols, the impact of ABCs on clouds, and the role of biogenic and anthropogenic aerosols on cloud condensation nuclei (CCN). In this talk, we will present the results from CAPMEX focusing on: (1) the characteristics of aerosol optical, physical and chemical properties at Gosan observatory, (2) aerosol solar heating calculated from the ground-based micro-pulse lidar and AERONET sun/sky radiometer synergy, and comparison with direct measurements from UAV, and (3) aerosol-cloud interactions in conjunction with measurements by satellites and Gosan observatory.

Kim, S.; Yoon, S.; Venkata Ramana, M.; Ramanathan, V.; Nguyen, H.; Park, S.; Kim, M.

2009-12-01

386

The volume of a cone, without calculus The volume V of a cone with base area A and height h is well known to be given  

E-print Network

The volume of a cone, without calculus The volume V of a cone with base area A and height h is well the cone formula, we'll also deduce the volume and the surface area of a sphere of radius R. Consider") and base area A. The volume of the frustum is V = cA(e + h) - cae. Now, the area of a cross

Hirschhorn, Mike

387

Study of cloud properties and processes in the polar regions by combining satellite and ground-based remote sensing measurements  

NASA Astrophysics Data System (ADS)

Clouds in the polar regions play an important roles in the hydrologic cycle, the local radiative balance, and polar sea ice. However, harsh climatic conditions and perennial snow and ice cover limits the collection of cloud data from the surface as well as the effectiveness of cloud detection with satellite passive sensors. Therefore, there is a lack of reliable data on polar clouds and their properties. This study combines active and passive measurements from the NASA A-Train satellites to overcome these shortcomings and to provide a novel approach to study on polar clouds. Multi-year CloudSat and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) data are used to investigate the characteristics of tropospheric clouds and precipitation systems, and their effect on the occurrence and microphysical properties of polar stratospheric clouds in the Antarctic region, south of 60 °S. The lidar and radar data are collocated to derive a combined cloud mask to improve detection of cloud vertical structure. Polar stratospheric clouds were detected using CALIPSO attenuated lidar scattering ratios (ALSR) at a horizontal resolution of 20 km to achieve good signal-to-noise ratios to allow the detection of tenuous PSCs. Clouds in the Antarctic region exhibit distinct land-sea and seasonal variabilities. The mean annual cloud occurrence is ~ 50 % over the continent and ~ 85 % over the ocean. Over the ocean the mean occurrence is higher in summer (90 %) than in winter (70 %). Low-level clouds contribute to more than 60 % of the total clouds. However, due to the extensive snow cover and cold surfaces in winter these low-level cloud occurrences are smaller in winter (50 %) than in summer (65 %). For ice clouds, both the effective radius and ice water content are larger in summer than in winter. High-level and deep tropospheric clouds strongly affect polar stratospheric cloud (PSC) occurrence and their microphysical properties by providing additional cooling of the lower stratosphere, especially during late winter and early spring. 70 % of all PSCs and 80 % of ice PSCs are formed in connection with tropospheric cloud systems during September and October. Similarly, PSCs associated with tropospheric cloud systems have higher particle number concentration than PSCs not associated with tropospheric cloud systems. A novel stratiform mixed-phase cloud retrieval algorithm has been developed by combining CloudSat, CALIPSO and Moderate Resolution Imaging Spectroradiometer (MODIS) measurements to address the large positive biases of the MODIS operational algorithm, which assumes a single liquid- or ice-phase in its retrieval for mixed-phase clouds. The algorithm is validated using collocated MODIS and ground-based measurements at the Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) North Slope Alaska (NSA) site. Results indicate that the new mixed-phase algorithm reduces the positive LWP biases of the operational MODIS algorithm from 35 % and 68 % to 10 % and 22 % over the temperature ranges of -5 to -10 °C and -10 to -20 °C, respectively.

Adhikari, Loknath

388

Structural Finite Element Method Based on Cloud Computing  

Microsoft Academic Search

The structural finite element method has been widely used in modern architecture high-performance computing. And a lot of finite element tools based on parallel computing model have emerged. This paper analyzes and compares the difference between MPI and Map Reduce programming model. The combination of MPI and Map Reduce has been presented for the parallel finite element analysis based on

Xin Zou; Xiao-qun Liu; Hong Fan; Zhen-li Cao

2012-01-01

389

The Roles of Cloud Drop Effective Radius and LWP in Determining Rain Properties in Marine Stratocumulus  

SciTech Connect

Numerical simulations described in previous studies showed that adding cloud condensation nuclei to marine stratocumulus can prevent their breakup from closed into open cells. Additional analyses of the same simulations show that the suppression of rain is well described in terms of cloud drop effective radius (re). Rain is initiated when re near cloud top is around 12-14 um. Cloud water starts to get depleted when column-maximum rain intensity (Rmax) exceeds 0.1 mm h-1. This happens when cloud-top re reaches 14 um. Rmax is mostly less than 0.1 mm h-1 at re<14 um, regardless of the cloud water path, but increases rapidly when re exceeds 14 um. This is in agreement with recent aircraft observations and theoretical observations in convective clouds so that the mechanism is not limited to describing marine stratocumulus. These results support the hypothesis that the onset of significant precipitation is determined by the number of nucleated cloud drops and the height (H) above cloud base within the cloud that is required for cloud drops to reach re of 14 um. In turn, this can explain the conditions for initiation of significant drizzle and opening of closed cells providing the basis for a simple parameterization for GCMs that unifies the representation of both precipitating and non-precipitating clouds as well as the transition between them. Furthermore, satellite global observations of cloud depth (from base to top), and cloud top re can be used to derive and validate this parameterization.

Rosenfeld, Daniel; Wang, Hailong; Rasch, Philip J.

2012-07-04

390

Airborne measurements of the impact of ground-based glaciogenic cloud seeding on orographic precipitation  

NASA Astrophysics Data System (ADS)

Data from in situ probes and a vertically-pointing mm-wave Doppler radar aboard a research aircraft are used to study the cloud microphysical effect of glaciogenic seeding of cold-season orographic clouds. A previous study (Geerts et al., 2010) has shown that radar reflectivity tends to be higher during seeding periods in a shallow layer above the ground downwind of ground-based silver iodide (AgI) nuclei generators. This finding is based on seven flights, conducted over a mountain in Wyoming (the Unites States), each with a no-seeding period followed by a seeding period. In order to assess this impact, geographically fixed flight tracks were flown over a target mountain, both upwind and downwind of the AgI generators. This paper examines data from the same flights for further evidence of the cloud seeding impact. Composite radar data show that the low-level reflectivity increase is best defined upwind of the mountain crest and downwind of the point where the cloud base intersects the terrain. The main argument that this increase can be attributed to AgI seeding is that it is confined to a shallow layer near the ground where the flow is turbulent. Yet during two flights when clouds were cumuliform and coherent updrafts to flight level were recorded by the radar, the seeding impact was evident in the flight-level updrafts (about 610 m above the mountain peak) as a significant increase in the ice crystal concentration in all size bins. The seeding effect appears short-lived as it is not apparent just downwind of the crest.

Miao, Qun; Geerts, Bart

2013-07-01

391

Measuring Effective Leaf Area Index, Foliage Profile, and Stand Height in New England Forest Stands Using a Full-Waveform Ground-Based Lidar  

NASA Technical Reports Server (NTRS)

Effective leaf area index (LAI) retrievals from a scanning, ground-based, near-infrared (1064 nm) lidar that digitizes the full return waveform, the Echidna Validation Instrument (EVI), are in good agreement with those obtained from both hemispherical photography and the Li-Cor LAI-2000 Plant Canopy Analyzer. We conducted trials at 28 plots within six stands of hardwoods and conifers of varying height and stocking densities at Harvard Forest, Massachusetts, Bartlett Experimental Forest, New Hampshire, and Howland Experimental Forest, Maine, in July 2007. Effective LAI values retrieved by four methods, which ranged from 3.42 to 5.25 depending on the site and method, were not significantly different ( b0.1 among four methods). The LAI values also matched published values well. Foliage profiles (leaf area with height) retrieved from the lidar scans, although not independently validated, were consistent with stand structure as observed and as measured by conventional methods. Canopy mean top height, as determined from the foliage profiles, deviated from mean RH100 values obtained from the Lidar Vegetation Imaging Sensor (LVIS) airborne large-footprint lidar system at 27 plots by .0.91 m with RMSE=2.04 m, documenting the ability of the EVI to retrieve stand height. The Echidna Validation Instrument is the first realization of the Echidna lidar concept, devised by Australia's Commonwealth Scientific and Industrial Research Organization (CSIRO), for measuring forest structure using full-waveform, ground-based, scanning lidar.

Zhao, Feng; Yang, Xiaoyuan; Schull, Mithcell A.; Roman-Colon, Miguel O.; Yao, Tian; Wang, Zhuosen; Zhang, Qingling; Jupp, David L. B.; Lovell, Jenny L.; Culvenor, Darius; Newnham, Glenn J.; Richardson, Andrew D.; Ni-Meister, Wenge; Schaaf, Crystal L.; Woodcock, Curtis E.; Strahler, Alan H.

2011-01-01

392

A High Performance Cloud-Based Protein-Ligand Docking Prediction Algorithm  

PubMed Central

The potential of predicting druggability for a particular disease by integrating biological and computer science technologies has witnessed success in recent years. Although the computer science technologies can be used to reduce the costs of the pharmaceutical research, the computation time of the structure-based protein-ligand docking prediction is still unsatisfied until now. Hence, in this paper, a novel docking prediction algorithm, named fast cloud-based protein-ligand docking prediction algorithm (FCPLDPA), is presented to accelerate the docking prediction algorithm. The proposed algorithm works by leveraging two high-performance operators: (1) the novel migration (information exchange) operator is designed specially for cloud-based environments to reduce the computation time; (2) the efficient operator is aimed at filtering out the worst search directions. Our simulation results illustrate that the proposed method outperforms the other docking algorithms compared in this paper in terms of both the computation time and the quality of the end result. PMID:23762864

Chen, Jui-Le; Yang, Chu-Sing

2013-01-01

393

2.5D multi-view gait recognition based on point cloud registration.  

PubMed

This paper presents a method for modeling a 2.5-dimensional (2.5D) human body and extracting the gait features for identifying the human subject. To achieve view-invariant gait recognition, a multi-view synthesizing method based on point cloud registration (MVSM) to generate multi-view training galleries is proposed. The concept of a density and curvature-based Color Gait Curvature Image is introduced to map 2.5D data onto a 2D space to enable data dimension reduction by discrete cosine transform and 2D principle component analysis. Gait recognition is achieved via a 2.5D view-invariant gait recognition method based on point cloud registration. Experimental results on the in-house database captured by a Microsoft Kinect camera show a significant performance gain when using MVSM. PMID:24686727

Tang, Jin; Luo, Jian; Tjahjadi, Tardi; Gao, Yan

2014-01-01

394

High-precision DEM reconstruction based on airborne LiDAR point clouds  

NASA Astrophysics Data System (ADS)

Airborne LiDAR point clouds have become important data sources for DEM generation recently; however the problem of low precision and low efficiency in DEM production still exists. This paper proposes a new technical scheme for high-precision DEM production based on airborne LiDAR point clouds systematically. Firstly, an elevation and density analysis method is applied to filter out outliers. Secondly, ground points are detected by an improved filter algorithm based on the hierarchical smoothing method. Finally, feature lines are extracted by the planar surface fitting and intersecting method, and a simple data structure of feature lines preserved DEM is proposed to achieve reconstructing high accuracy DEM, combing feature lines with ground points. Experimental results show that the proposed scheme is able to compensate for deficiencies of existing DEM reconstruction techniques and can meet the needs of high precision DEM production based on LiDAR data.

Xu, Jingzhong; Kou, Yuan; Wang, Jun

2014-05-01

395

2.5D Multi-View Gait Recognition Based on Point Cloud Registration  

PubMed Central

This paper presents a method for modeling a 2.5-dimensional (2.5D) human body and extracting the gait features for identifying the human subject. To achieve view-invariant gait recognition, a multi-view synthesizing method based on point cloud registration (MVSM) to generate multi-view training galleries is proposed. The concept of a density and curvature-based Color Gait Curvature Image is introduced to map 2.5D data onto a 2D space to enable data dimension reduction by discrete cosine transform and 2D principle component analysis. Gait recognition is achieved via a 2.5D view-invariant gait recognition method based on point cloud registration. Experimental results on the in-house database captured by a Microsoft Kinect camera show a significant performance gain when using MVSM. PMID:24686727

Tang, Jin; Luo, Jian; Tjahjadi, Tardi; Gao, Yan

2014-01-01

396

Cloud properties inferred from 8-12 micron data  

NASA Technical Reports Server (NTRS)

A trispectral combination of observations at 8-, 11-, and 12-micron bands is suggested for detecting cloud and cloud properties in the infrared. Atmospheric ice and water vapor absorption peak in opposite halves of the window region so that positive 8-minus-11-micron brightness temperature differences indicate cloud, while near-zero or negative differences indicate clear regions. The absorption coefficient for water increases more between 11 and 12 microns than between 8 and 11 microns, while for ice, the reverse is true. Cloud phases is determined by a scatter diagram of 8-minus-11-micron versus 11-minus-12-micron brightness temperature differences; ice cloud shows a slope greater than 1 and water cloud less than 1. The trispectral brightness temperature method was tested upon high-resolution interferometer data resulting in clear-cloud and cloud-phase delineation. Simulations using differing 8-micron bandwidths revealed no significant degradation of cloud property detection. Thus, the 8-micron bandwidth for future satellites can be selected based on the requirements of other applications, such as surface characterization studies. Application of the technique to current polar-orbiting High-Resolution Infrared Sounder (HIRS)-Advanced Very High Resolution Radiometer (AVHRR) datasets is constrained by the nonuniformity of the cloud scenes sensed within the large HIRS field of view. Analysis of MAS (MODIS Airborne Simulator) high-spatial resolution (500 m) data with all three 8-, 11-, and 12-micron bands revealed sharp delineation of differing cloud and background scenes, from which a simple automated threshold technique was developed. Cloud phase, clear-sky, and qualitative differences in cloud emissivity and cloud height were identified on a case study segment from 24 November 1991, consistent with the scene. More rigorous techniques would allow further cloud parameter clarification. The opportunities for global cloud delineation with the Moderate-Resolution Imaging Spectrometer (MODIS) appear excellent. The spectral selection, the spatial resolution, and the global coverage are all well suited for significant advances.

Strabala, Kathleen I.; Ackerman, Steven A.; Menzel, W. Paul

1994-01-01

397

Evolving agent-based simulations in the clouds  

Microsoft Academic Search

Evolving agent-based simulations enables one to automate the difficult iterative process of modeling complex adaptive systems to exhibit pre-specified\\/desired behaviors. Nevertheless this emerging technology, combining research advances in agent-based modeling\\/simulation and evolutionary computation, requires significant computing resources (i.e., high performance computing facilities) to evaluate simulation models across a large search space. Moreover, such experiments are typically conducted in an infrequent

James Decraene; Yong Yong Cheng; M. Y. H. Low; Suiping Zhou; Wentong Cai; Chwee Seng Choo

2010-01-01

398

Quantitative Measures of Immersion in Cloud and the Biogeography of Cloud Forests  

NASA Technical Reports Server (NTRS)

Sites described as tropical montane cloud forests differ greatly, in part because observers tend to differ in their opinion as to what constitutes frequent and prolonged immersion in cloud. This definitional difficulty interferes with hydrologic analyses, assessments of environmental impacts on ecosystems, and biogeographical analyses of cloud forest communities and species. Quantitative measurements of cloud immersion can be obtained on site, but the observations are necessarily spatially limited, although well-placed observers can examine 10 50 km of a mountain range under rainless conditions. Regional analyses, however, require observations at a broader scale. This chapter discusses remote sensing and modeling approaches that can provide quantitative measures of the spatiotemporal patterns of cloud cover and cloud immersion in tropical mountain ranges. These approaches integrate remote sensing tools of various spatial resolutions and frequencies of observation, digital elevation models, regional atmospheric models, and ground-based observations to provide measures of cloud cover, cloud base height, and the intersection of cloud and terrain. This combined approach was applied to the Monteverde region of northern Costa Rica to illustrate how the proportion of time the forest is immersed in cloud may vary spatially and temporally. The observed spatial variation was largely due to patterns of airflow over the mountains. The temporal variation reflected the diurnal rise and fall of the orographic cloud base, which was influenced in turn by synoptic weather conditions, the seasonal movement of the Intertropical Convergence Zone and the north-easterly trade winds. Knowledge of the proportion of the time that sites are immersed in clouds should facilitate ecological comparisons and biogeographical analyses, as well as land use planning and hydrologic assessments in areas where intensive on-site work is not feasible.

Lawton, R. O.; Nair, U. S.; Ray, D.; Regmi, A.; Pounds, J. A.; Welch, R. M.

2010-01-01

399

Dependence of radiative properties of Arctic stratus clouds on cloud microstructure  

NASA Astrophysics Data System (ADS)

Observations of cloud microstructure during the Beaufort Sea Arctic Stratus Cloud Experiments of June 1980 showed that the drop size distributions typically are nonuniform changing from monomodal near the base to bimodal near the top of the cloud. The observed drop size distributions are used to compute the reflection and transmission of solar radiation by Arctic Stratus Clouds in the visible part of the spectrum. Solutions of the radiative transfer equation using three different vertically uniform drop size distributions closely resembling those observed near the bottom, middle and top of the cloud, respectively, resulted in significant changes in the radiative properties even though the column liquid water content is kept constant. This finding implies that the shortwave optical depth of Arctic Stratus Clouds cannot be related to the column liquid water content (inferred from longwave satellite radiometry) unless realistic height-varying drop size distributions are used. It also implies that in order to make reliable predictions concerning the clouds' effect on the surface heat balance, one needs not only the column liquid water content but also height profiles of the drop size distributions.

Tsay, Si-Chee; Jayaweera, Kolf; Stamnes, Knut

1983-12-01

400

Nanoscale Modulation of Local Barrier Height on Bi-based Cuprate Superconductors Observed by Scanning Tunneling Microscopy\\/Spectroscopy  

Microsoft Academic Search

The atomically resolved local barrier height (LBH) of a Bi2Sr2CaCu2O8+delta (Bi2212) superconducting single crystal is investigated by using scanning tunneling microscopy\\/spectroscopy (STM\\/STS). The LBH distribution is found to be strongly related with the well-known supermodulation structure of the Bi2212 surface with a period of ˜2.7 nm. In particular, the magnitude of the LBH is anticorrelated to the Bi-Bi atomic distance

Akira Sugimoto; Toshikazu Ekino; Hiroshi Eisaki

2008-01-01

401

HydroConnector: A tool for estimating stage height of ungaged river site based on standardized hydro web services and HPG model  

NASA Astrophysics Data System (ADS)

Recently, River Information System that integrates a variety of riverine information has been widely developed driven by information technologies. In Korea, massive riverine data also have been incorporated into various specific River Information Systems, where such in-situ data and information system triggers new needs for active or real-time uses of them for numerical modeling or more advanced post-processing as a next step. Based on such new needs, the present study attempts to develop a software called HydroConnector that dynamically integrates river-based numerical modeling or post-processing with in-situ data based upon data searching technique using hydro web service built on top of a ODM-based database following a CUAHSI standard. It fundamentally differs from the conventional direct access to the database for acquiring a given period of dataset. Such a hydro web service and ODM-based database were built by utilizing existing real-time stream gaging data and they are dynamically connected with a HPG model that estimates stage height for a ungaged site. As a result, the newly developed HydroConnector is very intuitive for the user due to user-friendly GUI and facilitates modeling processes by automatically connecting remotely located data and a specific numerical model without further laborious data pre- and post-processing. In fact, HPG model consists of a pre-established diagram based on the simulated outputs from one-dimensional river models such as HEC-RAS operated for the possible flow conditions, and it is able to estimate the stage height for a ungaged site driven by the given downstream stage height and upstream flow discharge. The HydroConnector incorporates both the web service and the HPG model, which enables to make dynamic data pre-processing adjusted for the numerical model, and automatically operate the HPG model to finally provide the targeted ungaged stage height.

You, Hojun; Kim, Dongsu; Seo, Yongwon

2014-09-01

402

Ship-based remote sensing observations of clouds and aerosol over the Atlantic Ocean  

NASA Astrophysics Data System (ADS)

Within the framework of the OCEANET project, ship-based remote sensing observations of the atmosphere above the Atlantic Ocean have been performed on board of the German research vessels Polarstern and Meteor. Since 2007, twelve cruises took place, mostly between Bremerhaven (Germany) and Cape Town (South Africa) or Punta Arenas (Chile), respectively. In 2014 and 2015, two additional cruises will be performed. The goal of these ship-based measurements is a better understanding of water vapor, cloud and aerosol interaction over the open sea where data are scarce. The project was designed to measure the full atmospheric energy budget in different climate zones, including exchange processes at the sea surface. The main instrumentation on all cruises consisted of a passive microwave radiometer, a full sky imager, sun photometer, lidar ceilometer and broadband solar and infrared radiation measurements. In addition a multi wavelength Raman lidar (PollyXT) was on board of six cruises. Spectral solar radiance and irradiance observations have been performed on four cruises. With this dataset, a variety of topics can be addressed. This presentation will focus on marine stratocumulus clouds which are widespread over oceans and still pose a large uncertainty for determining the Earth's energy budget. Detailed studies for the northern trade wind zone off the West African coast will be presented. The emphasis lies on stratocumulus cloud properties, such as frequency, size, variability, liquid water content as well as their impact on surface radiation. Additionally, the influence of Saharan dust on the cloud occurrence will be addressed. Dust outbreaks over the ship could be observed in several years, including also at a cruise from the Caribbean Sea to Cape Verde in 2013. Furthermore, we will give a statistical overview of the meridional distribution of atmospheric water vapour and clouds over the Atlantic Ocean. With six years of measurements, always at the same time of the year, the variability of the atmospheric conditions in subtropical and tropical regions can be quantified.

Pospichal, Bernhard; Wolf, Veronika; Pietsch, Alexandra; Engelmann, Ronny; Macke, Andreas

2014-05-01

403

Cloud Distribution Statistics from LITE  

NASA Technical Reports Server (NTRS)

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.

Winker, David M.

1998-01-01

404

Measurements of cloud condensation nuclei spectra within maritime cumulus cloud droplets: Implications for mixing processes  

NASA Technical Reports Server (NTRS)

In a cloud formed during adiabatic expansion, the droplet size distribution will be systematically related to the critical supersaturation of the cloud condensation nuclei (CNN), but this relationship can be complicated in entraining clouds. Useful information about cloud processes, such as mixing, can be obtained from direct measurements of the CNN involved in droplet nucleation. This was accomplished by interfacing two instruments for a series of flights in maritime cumulus clouds. One instrument, the counterflow virtual impactor, collected cloud droplets, and the nonvolatile residual nuclei of the droplets was then passed to a CCN spectrometer, which measured the critical supersaturation (S(sub c)) spectrum of the droplet nuclei. The measured S(sub c) spectra of the droplet nuclei were compared with the S(sub c) spectra of ambient aerosol particles in order to identify which CCN were actually incorporated into droplets and to determine when mixing processes were active at different cloud levels. The droplet nuclei nearly always exhibited lower median S(sub c)'s than the ambient aerosol, as expected since droplets nucleate perferentially on particles with lower critical supersaturations. Critical supersaturation spectra from nuclei of droplets near cloud base were similar to those predicted for cloud regions formed adiabatically, but spectra of droplet nuclei from middle cloud levels showed some evidence that mixing had occurred. Near cloud top, the greatest variation in the spectra of the droplet nuclei was observed, and nuclei with high S(sub c)'s were sometimes present even within relatively large droplets. This suggests that the extent of mixing increases with height in cumulus clouds and that inhomogeneous mixing may be important near cloud top. These promising initial results suggest improvements to the experimental technique that will permit more quantitative results in future experiments.

Twohy, Cynthia H.; Hudson, James G.

1995-01-01

405

Cloud-Based Data Sharing Connects Emergency Managers  

NASA Technical Reports Server (NTRS)

Under an SBIR contract with Stennis Space Center, Baltimore-based StormCenter Communications Inc. developed an improved interoperable platform for sharing geospatial data over the Internet in real time-information that is critical for decision makers in emergency situations.

2014-01-01

406

CGtag: complete genomics toolkit and annotation in a cloud-based Galaxy  

PubMed Central

Background Complete Genomics provides an open-source suite of command-line tools for the analysis of their CG-formatted mapped sequencing files. Determination of; for example, the functional impact of detected variants, requires annotation with various databases that often require command-line and/or programming experience; thus, limiting their use to the average research scientist. We have therefore implemented this CG toolkit, together with a number of annotation, visualisation and file manipulation tools in Galaxy called CGtag (Complete Genomics Toolkit and Annotation in a Cloud-based Galaxy). Findings In order to provide research scientists with web-based, simple and accurate analytical and visualisation applications for the selection of candidate mutations from Complete Genomics data, we have implemented the open-source Complete Genomics tool set, CGATools, in Galaxy. In addition we implemented some of the most popular command-line annotation and visualisation tools to allow research scientists to select candidate pathological mutations (SNV, and indels). Furthermore, we have developed a cloud-based public Galaxy instance to host the CGtag toolkit and other associated modules. Conclusions CGtag provides a user-friendly interface to all research scientists wishing to select candidate variants from CG or other next-generation sequencing platforms’ data. By using a cloud-based infrastructure, we can also assure sufficient and on-demand computation and storage resources to handle the analysis tasks. The tools are freely available for use from an NBIC/CTMM-TraIT (The Netherlands Bioinformatics Center/Center for Translational Molecular Medicine) cloud-based Galaxy instance, or can be installed to a local (production) Galaxy via the NBIC Galaxy tool shed. PMID:24460651

2014-01-01

407

Large eddy simulations of Arctic stratus clouds  

NASA Astrophysics Data System (ADS)

Mixed-phase Arctic stratocumulus clouds are ubiquitous to the region during the summer months. However, despite their prevalence, very little is known about the processes which maintain the cloud. Recent observations have shown that Arctic stratocumulus commonly extend into the temperature inversion which caps the Arctic boundary layer. This is atypical to sub-tropical stratocumulus where the cloud top is found in the vicinity of the inversion base, and unexpected as strong longwave radiative cooling would be expected to keep the cloud top and inversion base heights in equilibrium. Uniquely to the Arctic, inversions in specific humidity are also commonly observed coincident with temperature inversions, and this is thought to contribute to the clouds' subsistence in the strongly stable inversion layer. . In this thesis, observations from the Arctic Summer Cloud Ocean Study (ASCOS) are used to characterize the lower Arctic atmosphere and provide the basis for simulations of stratocumulus cloud encroachment into the Arctic temperature inversion. Observations show that cloud extending into the inversion by more than 100 m was a common occurrence during ASCOS, which is consistent with measurements made during previous summer field campaigns. Simulations made with the Met Office Large Eddy Model (LEM) were used to model the encroachment, and results suggest that the depth of encroachment has a high correlation with the humidity inversion strength. A number of different cloud-inversion regimes were identified from the model simulations. When specific humidity fell of inside the temperature inversion, the high relative humidity of the region just above the inversion base was found to allow encroachment of cloud up to 40 m into the inversion layer. While in the presence of a specific humidity inversion the encroachment was larger reaching a maximum of 200 m. The presence of specific humidity inversions and their relationship to the encroaching cloud was determined to be self-sustaining, and the cloud found to remain at a quasi-stable depth for as long as a moisture source is available to replenish the loss of water from ice precipitation. However, encroachment of cloud into the inversion was shown to cause a significant reduction in the buoyant production of TKE at cloud top, which led to turbulence shutting off completely in the clouds with the largest encroachment depth. This caused a thermal adjustment of the inversion layer to the cloud which led a reduction in the encroachment depth. The overall impact of encroachment on boundary layer turbulence was found to be significant, with TKE reduced by up to 90% in the simulations with the largest encroachment depth..

Pleavin, Thomas Daniel

408

Cloud-Coffee: implementation of a parallel consistency-based multiple alignment algorithm in the T-Coffee package and its benchmarking on the Amazon Elastic-Cloud  

PubMed Central

Summary: We present the first parallel implementation of the T-Coffee consistency-based multiple aligner. We benchmark it on the Amazon Elastic Cloud (EC2) and show that the parallelization procedure is reasonably effective. We also conclude that for a web server with moderate usage (10K hits/month) the cloud provides a cost-effective alternative to in-house deployment. Availability: T-Coffee is a freeware open source package available from http://www.tcoffee.org/homepage.html Contact: cedric.notredame@crg.es PMID:20605929

Di Tommaso, Paolo; Orobitg, Miquel; Guirado, Fernando; Cores, Fernado; Espinosa, Toni; Notredame, Cedric

2010-01-01

409

Height prediction from ulna length.  

PubMed

Height is fundamental to assessing growth and nutrition, calculating body surface area, and predicting pulmonary function in childhood. Its measurement is hindered by muscle weakness, joint, or spinal deformity. Arm span has been used as a substitute, but is inaccurate. The objective of the study was to identify a limb measurement that precisely and reproducibly predicts height in childhood. Males (n=1144) and females (n=1199), aged 5 years 4 months to 19 years 7 months, without disability were recruited from Melbourne schools. Height, arm span, ulna, forearm, tibia, and lower leg lengths were measured with a Harpenden stadiometer and anthropometer. Prediction equations for height based on ulna length (U) and age in years (A) were developed using linear regression. Ulna centile charts were developed by the LMS method. For males, height (cm)=4.605U+1.308A+28.003 (R2=0.96); for females, height (cm)=4.459U+1.315A+31.485 (R2=0.94). Intra- and inter-observer variability was 0.41% and 0.61% relative to the mean, respectively. Height prediction equations from tibia, forearm, and lower leg length were calculated. We show that ulna measurement is reproducible and precisely predicts height in school-age children. It appears to be superior to arm span measurement when neuromuscular weakness, joint, or spinal deformity exists. Ulna growth charts should facilitate growth assessment. PMID:15230461

Gauld, Leanne M; Kappers, Johanna; Carlin, John B; Robertson, Colin F

2004-07-01

410

Geo-spatial Service and Application based on National E-government Network Platform and Cloud  

NASA Astrophysics Data System (ADS)

With the acceleration of China's informatization process, our party and government take a substantive stride in advancing development and application of digital technology, which promotes the evolution of e-government and its informatization. Meanwhile, as a service mode based on innovative resources, cloud computing may connect huge pools together to provide a variety of IT services, and has become one relatively mature technical pattern with further studies and massive practical applications. Based on cloud computing technology and national e-government network platform, "National Natural Resources and Geospatial Database (NRGD)" project integrated and transformed natural resources and geospatial information dispersed in various sectors and regions, established logically unified and physically dispersed fundamental database and developed national integrated information database system supporting main e-government applications. Cross-sector e-government applications and services are realized to provide long-term, stable and standardized natural resources and geospatial fundamental information products and services for national egovernment and public users.

Meng, X.; Deng, Y.; Li, H.; Yao, L.; Shi, J.

2014-04-01

411

Web-based interactive visualization of PS-InSAR point clouds for education and training  

NASA Astrophysics Data System (ADS)

In radar remote sensing education and training, only few people have a good knowledge of radar remote sensing and geology, which would be necessary fully analyse the surface motions estimated by persistent scatterer interferometry. Using scientific visualization, data can be presented in an intuitive way for surface motion analysis of non-radar experts. In this paper, we introduce a web-based interactive visualization of PS-InSAR point clouds for education and training.

Liang, D.; Balz, T.; Wang, Z. Y.; Wei, L. H.; Liao, M. S.

2014-04-01

412

NASA-Langley Web-Based Operational Real-time Cloud Retrieval Products from Geostationary Satellites  

NASA Technical Reports Server (NTRS)

At NASA Langley Research Center (LaRC), radiances from multiple satellites are analyzed in near real-time to produce cloud products over many regions on the globe. These data are valuable for many applications such as diagnosing aircraft icing conditions and model validation and assimilation. This paper presents an overview of the multiple products available, summarizes the content of the online database, and details web-based satellite browsers and tools to access satellite imagery and products.

Palikonda, Rabindra; Minnis, Patrick; Spangenberg, Douglas A.; Khaiyer, Mandana M.; Nordeen, Michele L.; Ayers, Jeffrey K.; Nguyen, Louis; Yi, Yuhong; Chan, P. K.; Trepte, Qing Z.; Chang, Fu-Lung; Smith, William L, Jr.

2006-01-01

413

Research on trust-based access control model in cloud computing  

Microsoft Academic Search

In this paper we propose a trust-based dynamic access control model for cloud computing environment inspired by the GTRBAC model, where the users can validate their legal identities and acquire their access control privileges for the resources according to the role information and the trust-degree in the lightweight certificates. The trust-degree in the certificate can be calculated by the direct

Zhanjiang Tan; Zhuo Tang; Renfa Li; Ahmed Sallam; Liu Yang

2011-01-01

414

Physics-Based Visualization of Dense Natural Clouds. I. Three-Dimensional Discrete Ordinates Radiative Transfer  

Microsoft Academic Search

A technique is developed to model radiative transfer in three-dimensional natural clouds with a standard discrete ordinates finite-element method modified to evaluate cell-surface-averaged radiances. A log-least-squares-based scale transformation is used to improve the discrete phase-function model. We handle dense media by assuming constant diffuse radiances over input faces to cubic cells, allowing analytical forms for transmittance factors. Transmission equations are

David H. Tofsted; Sean G. O'Brien

1998-01-01

415

Validation of a radiosonde-based cloud layer detection method against a ground-based remote sensing method at multiple ARM sites  

NASA Astrophysics Data System (ADS)

Cloud vertical structure is a key quantity in meteorological and climate studies, but it is also among the most difficult quantities to observe. In this study, we develop a long-term (10 years) radiosonde-based cloud profile product for the U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) program Southern Great Plains (SGP), Tropical Western Pacific (TWP), and North Slope of Alaska (NSA) sites and a shorter-term product for the ARM Mobile Facility (AMF) deployed in Shouxian, Anhui Province, China (AMF-China). The AMF-China site was in operation from 14 May to 28 December 2008; the ARM sites have been collecting data for over 15 years. The Active Remote Sensing of Cloud (ARSCL) value-added product (VAP), which combines data from the 95-GHz W-band ARM Cloud Radar (WACR) and/or the 35-GHz Millimeter Microwave Cloud Radar (MMCR), is used in this study to validate the radiosonde-based cloud layer retrieval method. The performance of the radiosonde-based cloud layer retrieval method applied to data from different climate regimes is evaluated. Overall, cloud layers derived from the ARSCL VAP and radiosonde data agree very well at the SGP and AMF-China sites. At the TWP and NSA sites, the radiosonde tends to detect more cloud layers in the upper troposphere.

Zhang, Jinqiang; Li, Zhanqing; Chen, Hongbin; Cribb, Maureen

2013-01-01

416

Affordable lidar for atmospheric aerosol and cloud studies  

NASA Astrophysics Data System (ADS)

The Vaisala ceilometer LD-40 'Tropopauser' is a compact eye-safe lidar measuring continuously under all possible climatic conditions and scanning the atmosphere up to a height of 13000 m. It uses laser diodes with 855 nm wavelength that are pulsed at an average frequency of 4000 Hz. The distance of the system's range bins is 7.5 m. Its main purpose is reporting cloud base heights and vertical visibility for aviation safety purposes. This paper focuses on the additional para