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1

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

2

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

3

Urbanization causes increased cloud base height and decreased fog in coastal Southern California  

NASA Astrophysics Data System (ADS)

Subtropical marine stratus clouds regulate coastal and global climate, but future trends in these clouds are uncertain. In coastal Southern California (CSCA), interannual variations in summer stratus cloud occurrence are spatially coherent across 24 airfields and dictated by positive relationships with stability above the marine boundary layer (MBL) and MBL height. Trends, however, have been spatially variable since records began in the mid-1900s due to differences in nighttime warming. Among CSCA airfields, differences in nighttime warming, but not daytime warming, are strongly and positively related to fraction of nearby urban cover, consistent with an urban heat island effect. Nighttime warming raises the near-surface dew point depression, which lifts the altitude of condensation and cloud base height, thereby reducing fog frequency. Continued urban warming, rising cloud base heights, and associated effects on energy and water balance would profoundly impact ecological and human systems in highly populated and ecologically diverse CSCA.

Williams, A. Park; Schwartz, Rachel E.; Iacobellis, Sam; Seager, Richard; Cook, Benjamin I.; Still, Christopher J.; Husak, Gregory; Michaelsen, Joel

2015-03-01

4

Inferring Low Cloud Base Heights at Night for Aviation Using Satellite Infrared and Surface Temperature Data  

NASA Astrophysics Data System (ADS)

A nighttime image product that depicts areas of the lowest cloud base heights has been developed by combining brightness temperature data from the Geostationary Operational Environmental Satellite (GOES) Imager InfraRed (IR) bands centered at 3.9 µm and 10.7 µm, with hourly shelter temperatures from surface observing sites and offshore marine buoys. A dependent data sample showed a good correlation between the surface temperature minus IR cloud top temperature differences versus measured cloud base heights. Histogram analysis indicated that a temperature difference of less than 4-C related to a > 50% frequency of ceilings below 1000 ft above ground level, the threshold for Instrument Flight Rules (IFR). Using this result as a model, an experimental Low Cloud Base image product was developed that highlights regions of likely IFR ceilings. Validation of the Low Cloud Base product for two separate periods resulted in Probabilities of Detection of 67% and 72% and False Alarm Rates of 6% and 11%, respectively. Some regional variation observed could be related to the relative frequency of multi-layered overcast conditions. The biggest factor leading to underdetection of IFR ceilings by the GOES Low Cloud Base product is the presence of overlying clouds, including thin cirrus contamination. The GOES Low Cloud Base product shows potential for use as guidance for aviation meteorologists over both continental and marine areas.

Ellrod, Gary P.; Gultepe, Ismail

2007-06-01

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

Cloud base and top heights in the Hawaiian region determined with satellite and ground-based measurements  

NASA Astrophysics Data System (ADS)

We present a multi-year climatology of cloud-base-height (CBH), cloud-top-height (CTH), and trade wind inversion base height (TWIBH) for the Hawaiian region (18°N-22.5°N, 153.7°W-160.7°W). The new climatology is based on data from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite (CALIPSO), the Constellation Observing System for Meteorology Ionosphere and Climate (COSMIC), ceilometer observations and radiosondes. The climatology reported here is well suited to evaluate climate model simulations and can serve as a reference state for studies of the impact of climate change on Hawaiian ecosystems. The averaged CBH from CALIPSO in the Hawaiian Region is 890 m. The mean CTH from CALIPSO is 2110 m, which is close to the mean TWIBH from COSMIC. For non-precipitating cases, the mean TWIBH at both Lihue and Hilo is close to 2000 m. For precipitating cases, the mean TWIBH is 2450 m and 2280 m at Hilo and Lihue, respectively. The potential cloud thickness (PCT) is defined as the difference between TWIBH and CBH and the mean PCT is several hundred meters thicker for precipitating than for the non-precipitating cases at both stations. We find that the PCT is more strongly correlated to the TWIBH than the CBH and that precipitation is unlikely to occur if the TWIBH is below 1500 m. The observed rainfall intensity is correlated to the PCT, i.e., thicker clouds are more likely to produce heavy rain.

Zhang, Chunxi; Wang, Yuqing; Lauer, Axel; Hamilton, Kevin; Xie, Feiqin

2012-08-01

7

Modeling atmospheric longwave radiation at the surface during overcast skies: The role of cloud base height  

NASA Astrophysics Data System (ADS)

behavior of the atmospheric downward longwave radiation at the surface under overcast conditions is studied. For optically thick clouds, longwave radiation depends greatly on the cloud base height (CBH), besides temperature and water vapor profiles. The CBH determines the cloud emission temperature and the air layers contributing to the longwave radiation that reaches the surface. Overcast situations observed at Girona (NE Iberian Peninsula) were studied by using a radiative transfer model. The data set includes different seasons, and a large range of CBH (0-5000 m). The atmosphere profiles were taken from the European Center for Medium-Range Weather Forecast analysis. The CBH was determined from ceilometer measurements and also estimated by using a suitable method applied to the vertical profile of relative humidity. The agreement between calculations and pyrgeometer measurements is remarkably good (1.6 ± 6.2 W m-2) if the observed CBH is used; poorer results are obtained with the estimated CBH (4.3 ± 7.0 W m-2). These results are better than those obtained from a simple parameterization based upon ground-level data (1.1 ± 11.6 W m-2), which can be corrected by adding a term that takes into account the CBH (-0.1 ± 7.3 W m-2). At this site, the cloud radiative effect (CRE) at the surface lies in the range 50-80 W m-2, has a clear seasonal behavior (higher CRE in winter), and depends upon the CBH. For the cold and the warm seasons, CRE decreases with CBH at a rate of -5 and -4 W m-2/km, respectively. Results obtained for other climates (subarctic and tropical) are also presented.

Viúdez-Mora, A.; Costa-Surós, M.; Calbó, J.; González, J. A.

2015-01-01

8

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

9

Observation-based estimation of cloud-top height by geostationary satellite split-window measurements trained with CloudSat data  

NASA Astrophysics Data System (ADS)

Look-up table for estimating the cloud-top height of upper-tropospheric clouds by the infrared brightness temperature (TB) at 10.8 ?m (T11) and its difference from TB at 12 ?m (?T11-12) measured by a geostationary satellite are presented. The look-up table was constructed by regressing the cloud radar measurements by the CloudSat satellite over the infrared measurements by the Japanese geostationary satellite MTSAT-1R. Standard deviations of measurements around the estimates were also displayed as an indicator of the ambiguity in the estimates, and were less than 1 km for the upper-tropospheric clouds with T11 < 240 K. The dependences of the estimates of cloud-top height at each point in T11-?T11-12 space on latitude, season, satellite zenith angle, day-night, and land-sea differences were examined. It was shown that these dependences were considered as being uniform in tropics, except for the region with large satellite zenith angle. The presented look-up tables can provide hourly estimates of cloud-top height at a specified location, and are fairly useful in comparing them with ground-based observations such as vertical profiles of humidity and/or wind.

Hamada, Atsushi; Nishi, Noriyuki

2010-11-01

10

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

11

An Assessment of MultiAngle Imaging SpectroRadiometer (MISR) Stereo-Derived Cloud Top Heights and cloud top winds using ground-based radar, lidar, and microwave radiometers  

SciTech Connect

Clouds are of tremendous importance to climate because of their direct radiative effects and because of their role in atmospheric dynamics and the hydrological cycle. The value of satellite imagery in monitoring cloud properties on a global basis can hardly be understated. One cloud property that satellites are in an advantageous position to monitor is cloud top height. Cloud top height retrievals are especially important for MISR because the derived height field is used to co-register the measured radiances. In this presentation we show the results of an ongoing comparison between ground-based millimeter-wave cloud radar and lidar measurements of cloud top and MISR stereo-derived cloud top height. This comparison is based on data from three radar systems located in the U.S Southern Great Plains (Lamont, Oklahoma), the Tropical Western Pacific (Nauru Island) and the North Slope of Alaska (Barrow, Alaska). These radars are operated as part of the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) program. The MISR stereo height algorithm is performing largely as expected for most optically thick clouds. As with many satellite retrievals, the stereo-height retrieval has difficulty with optically thin clouds or ice clouds with little optical contrast near cloud top.

Marchand, Roger T.; Ackerman, Thomas P.; Moroney, C.

2007-03-17

12

The Role of Cloud Base Height in the Convective Vigor and Flash Rate of Thunderstorms  

Microsoft Academic Search

Earlier studies of atmospheric convection have established the following results: (1) Convective Available Potential Energy (CAPE) over tropical land areas is of the same order as over warm ocean regions, (2) updraft strengths in continental clouds are more than twice those in oceanic clouds, (3) cumulonimbus updraft widths are larger over land than over ocean, (4) thermal widths in the

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

2002-01-01

13

Crop height determination with UAS point clouds  

NASA Astrophysics Data System (ADS)

The accurate determination of the height of agricultural crops helps to predict yield, biomass etc. These relationships are of great importance not only for crop production but also in grassland management, because the available biomass and food quality are valuable information. However there is no cost efficient and automatic system for the determination of the crop height available. 3D-point clouds generated from high resolution UAS imagery offer a new alternative. Two different approaches for crop height determination are presented. The "difference method" were the canopy height is determined by taking the difference between a current UAS-surface model and an existing digital terrain model (DTM) is the most suited and most accurate method. In situ measurements, vegetation indices and yield observations correlate well with the determined UAS crop heights.

Grenzdörffer, G. J.

2014-11-01

14

Exploiting the sensitivity of two satellite cloud height retrievals to cloud vertical distribution  

NASA Astrophysics Data System (ADS)

This work presents a study on the sensitivity of two satellite cloud height retrievals to cloud vertical distribution. The difference in sensitivity is exploited by relating the difference in the retrieved cloud heights to cloud vertical extent. The two cloud height retrievals, performed within the Freie Universität Berlin AATSR MERIS Cloud (FAME-C) algorithm, are based on independent measurements and different retrieval techniques. First, cloud top temperature (CTT) is retrieved from Advanced Along Track Scanning Radiometer (AATSR) measurements in the thermal infrared. Second, cloud top pressure (CTP) is retrieved from Medium Resolution Imaging Spectrometer (MERIS) measurements in the oxygen-A absorption band. Both CTT and CTP are converted to cloud top height (CTH) using atmospheric profiles from a numerical weather prediction model. A sensitivity study using radiative transfer simulations in the near-infrared and thermal infrared were performed to demonstrate the larger impact of the assumed cloud vertical extinction profile on MERIS than on AATSR top-of-atmosphere measurements. The difference in retrieved CTH (?CTH) from AATSR and MERIS are related to cloud vertical extent (CVE) as observed by ground-based lidar and radar at three ARM sites. To increase the impact of the cloud vertical extinction profile on the MERIS-CTP retrievals, single-layer and geometrically thin clouds are assumed in the forward model. The results of the comparison to the ground-based observations were separated into single-layer and multi-layer cloud cases. Analogous to previous findings, the MERIS-CTP retrievals appear to be close to pressure levels in the middle of the cloud. Assuming a linear relationship, the ?CTH multiplied by 2.5 gives an estimate on the CVE for single-layer clouds. The relationship is weaker for multi-layer clouds. Due to large variations of cloud vertical extinction profiles occurring in nature, a quantitative estimate of the cloud vertical extent is accompanied with large uncertainties. Yet, estimates of the CVE can contribute to the characterization of a cloudy scene. To demonstrate the plausibility of the approach, an estimate of the CVE was applied to a case study. In light of the follow-up mission Sentinel-3 with AATSR and MERIS like instruments, Sea and Land Surface Temperature Radiometer (SLSTR) and (Ocean and Land Colour Instrument) OLCI, respectively, for which the FAME-C algorithm can be easily adapted, a more accurate estimate of the CVE can be expected. OLCI will have three channels in the oxygen-A absorption band, thus providing more pieces of information on the cloud vertical extinction profile.

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

2015-03-01

15

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

16

Analysis of cloud top height and cloud coverage from satellites using the O2 A and B bands  

NASA Technical Reports Server (NTRS)

Cloud height and cloud coverage detection are important for total ozone retrieval using ultraviolet and visible scattered light. Use of the O2 A and B bands, around 761 and 687 nm, by a satellite-borne instrument of moderately high spectral resolution viewing in the nadir makes it possible to detect cloud top height and related parameters, including fractional coverage. The measured values of a satellite-borne spectrometer are convolutions of the instrument slit function and the atmospheric transmittance between cloud top and satellite. Studies here determine the optical depth between a satellite orbit and the Earth or cloud top height to high accuracy using FASCODE 3. Cloud top height and a cloud coverage parameter are determined by least squares fitting to calculated radiance ratios in the oxygen bands. A grid search method is used to search the parameter space of cloud top height and the coverage parameter to minimize an appropriate sum of squares of deviations. For this search, nonlinearity of the atmospheric transmittance (i.e., leverage based on varying amounts of saturation in the absorption spectrum) is important for distinguishing between cloud top height and fractional coverage. Using the above-mentioned method, an operational cloud detection algorithm which uses minimal computation time can be implemented.

Kuze, Akihiko; Chance, Kelly V.

1994-01-01

17

Thunderstorm cloud height-rainfall rate relations for use with satellite rainfall estimation techniques  

NASA Technical Reports Server (NTRS)

Observational studies of thunderstorm cloud height-rainfall rate and cloud height-volume rainfall rate relations are reviewed with significant variations being noted among climatological regimes. Analysis of the Florida (summer) and Oklahoma (spring) relations are made using a one-dimensional cloud model to ascertain the important factors in determining the individual cloud-rain relations and the differences between the two regimes. In general, the observed relations are well simulated by the model-based calculations. The generally lower predicted rain rates in Oklahoma (as compared to Florida) result from lower precipitation efficiencies which are due to a combination of larger entrainment (related to larger vertical wind shear) and drier environment. The generally steeper slope of the Oklahoma rain rate height curves is shown to be due to a stronger variation in maximum vertical velocity with cloud top height, which, in turn, is related to the greater static stability in the range of cloud tops. The impact of the regime-to-regime variations on empirical rain estimation schemes based on satellite-observed cloud height or cloud temperature information is discussed and a rain estimation approach based on model-generated cloud-rain relations is outlined.

Adler, R. F.; Mack, R. A.

1984-01-01

18

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

19

Cloud-Top Height Estimation by Geostationary Satellite Split-Window Measurements using CloudSat Measurements  

NASA Astrophysics Data System (ADS)

Estimation of cloud-top height and visible optical thickness of upper-tropospheric clouds by brightness temperature (TB) measurements of geostationary satellite at two infrared split-window wavelengths was conducted. These cloud parameters were estimated by regressing the measurements of 94-GHz cloud radar onboard CloudSat satellite in terms of TB at 10.8 um (T11) and its difference from TB at 12 um (?T = T11 - T12) measured by geostationary satellite MTSAT-1R. Estimation by geostationary satellite measurements are fairly useful in field campaigns aiming mesoscale cloud systems, where cloud-top heights are compared with the vertical profiles of ground-based measurements such as wind and cloud condensates in a short time interval. Hamada et al. (2008) conducted the estimation of cloud-top height by T11 and ?T measured by GMS-5, using ship-borne cloud radar measurements. However, their ground-based result was limited to the non-rainy clouds, since cloud radar signal is heavily attenuated by precipitation particles. Spaceborne radar measurements enables an estimation of cloud-top height without concern for the existence of precipitation. We examined the dependences of the estimates of cloud-top height on latitude, season, satellite zenith angle, day-night, and land-sea differences. It was shown that these dependences were considered as being uniform in tropics, except for the region with large satellite zenith angle. The dependences on latitude and season were negligible in tropics, while they became the most significant factor affecting the estimates at higher latitudes. Estimation of visible optical thickness was also conducted, although limited to the non-rainy high clouds. The distributions of estimates in TB-?T space were qualitatively consistent with those expected from a simplified radiative transfer equation, although the standard deviations of measurements were slightly large. Since the CloudSat conducts cloud radar observations on a global scale, the method adopted in this study can easily be applied to other current geostationary satellites with split-window channels, yielding hourly estimation map of cloud-top and optical thickness in global scale. We are planning to provide the near real-time product at our Website. Estimates (shading and thin solid contours) and standard deviations of samples (dashed contours) for cloud-top height by T11 and ?T.

Hamada, A.; Nishi, N.

2009-12-01

20

A Qualitative Comparison between MISR and Cloud Radar Cloud Heights at the North Slope of Alaska ARM Site paquita.zuidema@noaa.gov  

E-print Network

A Qualitative Comparison between MISR and Cloud Radar Cloud Heights at the North Slope of Alaska at 10:10 AM local time or ~23:00 UTC.The Pt.Barrow site is also known as the North Slope of Alaska (NSA between cloud heights as perceived by a surface-based cloud radar located at Pt.Barrow,Alaska (71.2N,156

Zuidema, Paquita

21

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

22

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

23

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

24

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

25

Tornado occurrences related to overshooting cloud-top heights as determined from ATS pictures  

NASA Technical Reports Server (NTRS)

A sequence of ATS 3 pictures including the development history of large anvil clouds near Salina, Kansas was enlarged by NASA into 8X negatives which were used to obtain the best quality prints by mixing scan lines in 8 steps to minimize checker-board patterns. These images resulted in the best possible resolution, permitting use to compute the heights of overshooting tops above environmental anvil levels based on cloud shadow relationships along with the techniques of lunar topographic mapping. Of 39 heights computed, 6 were within 15 miles of reported positions of 3 tornadoes. It was found that the tornado proximity tops were mostly less than 5000 ft, with one exception of 7000 ft, suggesting that tornadoes are most likely to occur when overshooting height decreases. In order to simulate surface vortices induced by cloud-scale rotation and updraft fields, a laboratory model was constructed. The model experiment has shown that the rotation or updraft field induces a surface vortex but their combination does prevent the formation of the surface vortex. This research leads to a conclusion that the determination of the cloud-top topography and its time variation is of extreme importance in predicting severe local storms for a period of 0 to 6 hours.

Fujita, T. T.

1972-01-01

26

Deep convective cloud-top heights and their thermodynamic control during CRYSTAL-FACE  

Microsoft Academic Search

Infrared (11 mum) 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 (Z11) reached approximately

Steven C. Sherwood; Patrick Minnis; Matthew McGill

2004-01-01

27

Deep convective cloud-top heights and their thermodynamic control during CRYSTAL-FACE  

Microsoft Academic Search

Infrared (11 ?m) 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 (Z11) reached approximately

Steven C. Sherwood; Patrick Minnis; Matthew McGill

2004-01-01

28

Development of a Cloud-Top Height Estimation Method by Geostationary Satellite Split-Window Measurements Trained with CloudSat Data  

NASA Astrophysics Data System (ADS)

Estimation of cloud-top height and visible optical thickness of upper-tropospheric clouds by brightness temperature (TB) measurements of geostationary satellite at two infrared split-window wavelengths was conducted. These cloud parameters were estimated by regressing the measurements of 94-GHz cloud radar onboard CloudSat satellite in terms of TB at 10.8 um (T11) and its difference from TB at 12 um (?T = T11 -T12) measured by geostationary satellite MTSAT-1R. Estimation by geostationary satellite measurements are fairly useful in field campaigns aiming mesoscale cloud systems, where cloud-top heights are compared with the vertical profiles of ground-based measurements such as wind and cloud condensates in a short time interval. Hamada et al. (2008) conducted the estimation of cloud-top height by T11 and ?T measured by GMS-5, using ship-borne cloud radar measurements. However, their ground-based result was limited to the non-rainy clouds, since cloud radar signal is heavily attenuated by precipitation particles. Spaceborne radar measurements enables an estimation of cloud-top height without concern for the existence of precipitation. We examined the dependences of the estimates of cloud-top height on latitude, season, satellite zenith angle, day-night, and land-sea differences. It was shown that these dependences were considered as being uniform in tropics, except for the region with large satellite zenith angle. The dependences on latitude and season were negligible in tropics, while they became the most significant factor affecting the estimates at higher latitudes. Estimation of visible optical thickness was also conducted, although limited to the non-rainy high clouds. The distributions of estimates in TB-?T space were qualitatively consistent with those expected from a simplified radiative transfer equation, although the standard deviations of measurements were slightly large. The near real-time products has already been provided on our Website (http://www-clim.kugi.kyoto-u.ac.jp/hamada/ctop/). Since the CloudSat conducts cloud radar observations on a global scale, the method adopted in this study can easily be applied to other current geostationary satellites with split-window channels, yielding hourly estimation map of cloud-top and optical thickness in global scale. We will show the results also using Meteosat Second Generation measurements.

Hamada, Atsushi; Nishi, Noriyuki; Inoue, Toshiro

2010-05-01

29

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

30

Arctic PBL Cloud Height and Motion Retrievals from MISR and MINX  

NASA Technical Reports Server (NTRS)

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

Wu, Dong L.

2012-01-01

31

A comparison of several techniques to assign heights to cloud tracers  

NASA Technical Reports Server (NTRS)

Experimental results are presented which suggest that the water-vapor technique of radiance measurement is a viable alternative to the CO2 technique for inferring the height of semitransparent cloud elements. Future environmental satellites will rely on H2O-derived cloud-height assignments in the wind-field determinations with the next operational geostationary satellite. On a given day, the heights from the H2O and CO2 approaches compare to within 60-110 hPa rms.

Nieman, Steven J.; Schmetz, Johannes; Menzel, W. P.

1993-01-01

32

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

33

Thermal disequilibrium at the top of volcanic clouds and its effect on estimates of the column height  

NASA Technical Reports Server (NTRS)

Satellite images of large volcanic explosions reveal that the tops of volcanic eruptions columns are much cooler than the surrounding atmosphere. It is proposed that this effect occurs whenever a mixture of hot volcanic ash and entrained air ascends sufficiently high into a stably stratified atmosphere. Although the mixture is initially very hot, it expands and cools as the ambient pressure decreases. It is shown that cloud-top undercoolings in excess of 20 C may develop in clouds that penetrate the stratosphere, and it is predicted that, for a given cloud-top temperature, variations in the initial temperature of 100-200 C may correspond to variations in the column height of 5-10 km. It is deduced that the present practice of converting satellite-based measurements of the temperature at the top of volcanic eruptions columns to estimates of the column height will produce rather inaccurate results and should therefore be discontinued.

Woods, Andrew W.; Self, Stephen

1992-01-01

34

Photogrammetric retrieval of volcanic ash cloud top height from SEVIRI and MODIS  

NASA Astrophysics Data System (ADS)

Even if erupting in remote areas, volcanoes can have a significant impact on the modern society due to volcanic ash dispersion in the atmosphere. The ash does not affect merely air traffic - its transport in the atmosphere and its deposition on land and in the oceans may also significantly influence the climate through modifications of atmospheric CO2. The emphasis of this contribution is the retrieval of volcanic ash plume height (ACTH). ACTH is important information especially for air traffic but also to predict ash transport and to estimate the mass flux of the ejected material. ACTH is usually estimated from ground measurements, pilot reports, or satellite remote sensing. But ground based instruments are often not available at remote volcanoes and also the pilots reports are a matter of chance. Volcanic ash cloud top height (ACTH) can be monitored on the global level using satellite remote sensing. The most often used method compares brightness temperature of the cloud with the atmospheric temperature profile. Because of uncertainties of this method (unknown emissivity of the ash cloud, tropopause, etc.) we propose photogrammetric methods based on the parallax between data retrieved from geostationary (SEVIRI) and polar orbiting satellites (MODIS). The parallax is estimated using automatic image matching in three level image pyramids. The procedure works well if the data from both satellites are retrieved nearly simultaneously. MODIS does not retrieve the data at exactly the same time as SEVIRI. To compensate for advection we use two sequential SEVIRI images (one before and one after the MODIS retrieval) and interpolate the cloud position from SEVIRI data to the time of MODIS retrieval. ACTH is then estimated by intersection of corresponding lines-of-view from MODIS and interpolated SEVIRI data. The proposed method was tested using MODIS band 1 and SEVIRI HRV band for the case of the Eyjafjallajökull eruption in April 2010. The parallax between MODIS and SEVIRI data can reach over 30 km which implies ACTH of more than 12 km. The accuracy of ACTH was estimated to 0.6 km. The limitation of this procedure is that it has difficulties with automatic image matching if the ash cloud is not opaque.

Zakšek, Klemen; Hort, Matthias; Zaletelj, Janez; Langmann, Bärbel

2013-04-01

35

Retrieval of cloud fraction and height anomalies and their trend from temporally and spatially averaged infrared spectra observed from space  

NASA Astrophysics Data System (ADS)

Understanding how clouds and atmospheric properties change with time under radiative forcing is necessary to understand feedback. Generally, global clouds and atmospheric Understanding how clouds and atmospheric properties change with time under radiative forcing is necessary to understand feedback. Generally, global clouds and atmospheric properties are retrieved from satellite-based instruments. Subsequently, retrieved values from an instrument's field-of-view are averaged and the time rate of change of cloud or atmospheric properties can be inferred from averaged properties. This is simple in concept but identifying artifacts of the retrieval is difficult in practice. An alternative way to derive a trend of cloud and atmospheric properties is tying their property change directly to the observed radiance change. This average-then-retrieve approach directly utilizes instrument stability but requires separating cloud and atmospheric property changes contributing to the highly spatially and temporally averaged observed radiance change. In this presentation, we demonstrate the average-then-retrieve approach by simulating the retrieval of cloud fraction and height anomalies from highly averaged longwave spectra. We use 28 years of reanalysis (Modern Era Retrospective-Analysis for Research MERRA) for the simulation and retrieve annual 10° zonal cloud fraction and height anomalies, as well as temperature and water vapor amount anomalies. The error in retrieved anomalies is estimated based on the method discussed in Kato et al. (2011). The uncertainty in the trend estimated from retrieved anomalies is also discussed. Reference Kato, S., B. A. Wielicki, F. G. Rose, X. Liu, P. C. Taylor, D. P. Kratz, M. G. Mlynczak, D. F. Young, N. Phojanamongkolkij, S. Sun-Mack, W. F. Miller, Y. Chen, 2011b, Detection of atmospheric changes in spatially and temporally averaged infrared spectra observed from space, J Climate, 24, 6392-6407, Doi: 10.1175/JCLI-D-10-05005.1.

Kato, S.; Rose, F. G.; Liu, X.; Wielicki, B. A.; Mlynczak, M. G.

2013-12-01

36

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

E-print Network

MISR 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 data to retrieve or estimate the cloud height and hence cloud detection. However, cloud detection even

Sekhon, Jasjeet S.

37

First height comparison of noctilucent clouds and simultaneous PMSE  

NASA Technical Reports Server (NTRS)

On the night of August 9-10, 1991, two rocket payloads were launched into simultaneously occurring noctilucent clouds (NLC) and polar mesospheric summer echoes (PMSE) above Esrange, a third rocket payload was launched into a NLC where a PMSE was detected 5 minutes later above Esrange, in Sweden as part of the NLC-91 campaign. An aim of this experiment was to compare the vertical structures and locations of the NLC and PMSE events. To this end, in-situ optical photometers and particle impact sensors were used to measure the altitude and vertical structure of the NLC layer, while the Cornell University portable radar interferometer (CUPRI) was used to probe the PMSE. Although this comparison is complicated by the horizontal separations between the in-situ measurements and the radar volume, and low electron densities which reduced the overall radar reflectivity, we conclude that the PMSE layer in the CUPRI radar volume remained above the NLC layer detected by the in-situ instruments by 300 to 2000 m throughout the experiment. We interpret this result as supporting the view that PMSE are more likely to result from the presence of aerosols smaller than the ones optically detectable as NLCs.

Waelchli, Urs; Stegman, Jacek; Witt, Georg; Cho, John Y. N.; Miller, Clark A.; Kelley, Michael C.; Swartz, Wesley E.

1993-01-01

38

Cloud Height Retrieval with Oxygen A and B Bands for the Deep Space Climate Observatory (DSCOVR) Mission  

NASA Technical Reports Server (NTRS)

Planned to fly in 2014, the Deep Space Climate Observatory (DSCOVR) would see the whole sunlit half of the Earth from the L 1 Lagrangian point and would provide simultaneous data on cloud and aerosol properties with its Earth Polychromatic Imaging Camera (EPIC). EPIC images the Earth on a 2Kx2K CCD array, which gives a horizontal resolution of about 10 km at nadir. A filter-wheel provides consecutive images in 10 spectral channels ranging from the UV to the near-IR, including the oxygen A and B bands. This paper presents a study of retrieving cloud height with EPIC's oxygen A and B bands. As the first step, we analyzed the effect of cloud optical and geometrical properties, sun-view geometry, and surface type on the cloud height determination. Second, we developed two cloud height retrieval algorithms that are based on the Mixed Lambertian-Equivalent Reflectivity (MLER) concept: one utilizes the absolute radiances at the Oxygen A and B bands and the other uses the radiance ratios between the absorption and reference channels of the two bands. Third, we applied the algorithms to the simulated EPIC data and to the data from SCanning Imaging Absorption SpectroMeter for Atmospheric CartograpHY (SCIAMACHY) observations. Results show that oxygen A and B bands complement each other: A band is better suited for retrievals over ocean, while B band is better over vegetated land due to a much darker surface. Improvements to the MLER model, including corrections to surface contribution and photon path inside clouds, will also be discussed.

Yang, Yuekui; Marshak, Alexander; Mao, Jianping; Lyapustin, Alexei; Herman, Jay

2012-01-01

39

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

NASA Astrophysics Data System (ADS)

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 5 million CTH comparisons for the months of August 2006 and February 2007. To facilitate the comparison, a computationally efficient and accurate collocation methodology is developed. With the collocated MODIS and CALIOP retrievals, nearly instantaneous comparisons are compiled regionally and globally. Globally, it is found that the MODIS 1-km cloud mask and the CALIOP 1-km averaged layer product agreement is 87% for cloudy conditions for both August 2006 and February 2007. For clear-sky conditions the agreement is 85% (86%) for August (February). The best agreement is found for nonpolar daytime and the poorest agreement in the polar regions. Differences in cloud top heights depend strongly on cloud type. Globally, MODIS underestimates the CTH relative to CALIOP by 1.4 ± 2.9 km for both August 2006 and February 2007. This value of 1.4 km is obtained using the CALIOP 1 km layer products. When compared to the CALIOP 5-km products, the differences increase to -2.6 ± 3.9 km as a result of CALIOP's increased sensitivity to optically thin cirrus. When only high clouds above 5 km are considered, the differences are found to be greater than 4 km with individual comparisons having differences larger than 10 km. These large differences (>10 km) represent approximately 16% of the nonpolar high cloud retrievals (>5 km). For high clouds it is found that MODIS retrieves a cloud top height for 90% of the clouds detected by the CALIOP 5-km layer products. The large MODIS underestimates for optically thin cirrus occur for cases when MODIS reverts to a window brightness temperature retrieval instead of CO2 slicing. A systematic bias is found for marine low-level stratus clouds, with MODIS overestimating the CTH by over 1 km in dense marine stratocumulus regions. The cause of the bias was identified in the MODIS Collection 5 algorithm; an application of a modified algorithm reduced this bias.

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

2008-04-01

40

Cloudy sounding and cloud-top height retrieval from AIRS alone single field-of-view radiance measurements  

E-print Network

Cloudy sounding and cloud-top height retrieval from AIRS alone single field-of-view radiance. This paper presents an AIRS alone single field- of-view (SFOV) retrieval algorithm to simultaneously retrieve and cloud-top height retrieval from AIRS alone single field-of-view radiance measurements, Geophys. Res

Li, Jun

41

Predicting Daily Insolation with Hourly Cloud Height and Coverage  

Microsoft Academic Search

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

T. P. Meyers; R. F. Dale

1983-01-01

42

CloudSat-constrained cloud ice water path and cloud top height retrievals from MHS 157 and 183.3 GHz radiances  

NASA Astrophysics Data System (ADS)

Ice water path (IWP) and cloud top height (ht) are two of the key variables in determining cloud radiative and thermodynamical properties in climate models. Large uncertainty remains among IWP measurements from satellite sensors, in large part due to the assumptions made for cloud microphysics in these retrievals. In this study, we develop a fast algorithm to retrieve IWP from the 157, 183.3 ± 3 and 190.3 GHz radiances of the Microwave Humidity Sounder (MHS) such that the MHS cloud ice retrieval is consistent with CloudSat IWP measurements. This retrieval is obtained by constraining the empirical forward models between collocated and coincident measurements of CloudSat IWP and MHS cloud-induced radiance depression (Tcir) at these channels. The empirical forward model is represented by a look-up table (LUT) of Tcir-IWP relationships as a function of ht and the frequency channel. With ht simultaneously retrieved, the IWP is found to be more accurate. The useful range of the MHS IWP retrieval is between 0.5 and 10 kg m-2, and agrees well with CloudSat in terms of the normalized probability density function (PDF). Compared to the empirical model, current operational radiative transfer models (RTMs) still have significant uncertainties in characterizing the observed Tcir-IWP relationships. Therefore, the empirical LUT method developed here remains an effective approach to retrieving ice cloud properties from the MHS-like microwave channels.

Gong, J.; Wu, D. L.

2014-06-01

43

A neural network approach for monitoring of volcanic SO2 and cloud height using hyperspectral measurements  

NASA Astrophysics Data System (ADS)

In this study two neural networks were implemented in order to emulate a retrieval model and to estimate the sulphur dioxide (SO2) columnar content and cloud height from volcanic eruption. ANNs were trained using all Infrared Atmospheric Sounding Interferometer (IASI) channels in Thermal Infrared (TIR) as inputs, and the corresponding values of SO2 content and height of volcanic cloud obtained using the Oxford SO2 retrievals as target outputs. The retrieval is demonstrated for the eruption of the Eyjafjallajökull volcano (Iceland) occurred in 2010 and to three IASI images of the Grímsvötn volcanic eruption that occurred in May 2011, in order to evaluate the networks for an unknown eruption. The results of validation, both for Eyjafjallajökull independent data-sets, provided root mean square error (RMSE) values between neural network outputs and targets lower than 20 DU for SO2 total column and 200 mb for cloud height, therefore demonstrating the feasibility to estimate SO2 values using a neural network approach, and its importance in near real time monitoring activities, owing to its fast application. Concerning the validation carried out with neural networks on images from the Grímsvötn eruption, the RMSE of the outputs remained lower than the Standard Deviation (STD) of targets, and the neural network underestimated retrieval only where target outputs showed different statistics than those used during the training phase.

Piscini, Alessandro; Carboni, Elisa; Del Frate, Fabio; Grainger, Roy Gordon

2014-10-01

44

The upper clouds of Venus: Determination of the scale height from NIMS-Galileo infrared data  

NASA Technical Reports Server (NTRS)

The 3-5 micrometer thermal emission of the nightside of Venus, recorded by the Near-Infrared Mapping Spectrometer (NIMS) instrument at the time of the Galileo flyby of Venus, is analysed to infer the properties of the upper cloud boundary. From the global maps of Venus at fixed wavelengths, the limb darkening of the flux is measured at several latitudes, within each infrared channel. By using the nominal Pioneer Venus thermal profile, these data give access to two parameters: the cloud deck temperature and the cloud scale height. It is verified independently, from the NIMS spectra, that this thermal profile is consistent with all the NIMS observations, and that the thermal structure does not vary significantly in the latitude range (25 deg S, 30 deg N). Within this range, the cloud scale height is found to be constant with latitude, and is H = 5.2 km, with an accuracy of about 15%, taking into account the various sources of theoretical and observational uncertainties. At higher latitudes, the temperature profile becomes more isothermal and the presented method to retrieve H is no longer valid.

Roos, M.; Drossart, P.; Encrenaz, TH.; Lellouch, E.; Bezard, B.; Carlson, R. W.; Baines, K. H.; Kamp, L. W.; Taylor, F. W.; Collard, A. D.

1993-01-01

45

Remote sensing of cloud top pressure/height from SEVIRI: analysis of ten current retrieval algorithms  

NASA Astrophysics Data System (ADS)

The role of clouds remains the largest uncertainty in climate projections. They influence solar and thermal radiative transfer and the earth's water cycle. Therefore, there is an urgent need for accurate cloud observations to validate climate models and to monitor climate change. Passive satellite imagers measuring radiation at visible to thermal infrared wavelengths provide a wealth of information on cloud properties. Among others, the cloud top height (CTH) - a crucial parameter to estimate the thermal cloud radiative forcing - can be retrieved. In this paper we investigate the skill of ten current retrieval algorithms to estimate the CTH using observations from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) onboard Meteosat Second Generation (MSG). In the first part we compare the ten SEVIRI cloud top pressure (CTP) datasets with each other. The SEVIRI algorithms catch the latitudinal variation of the CTP in a similar way. The agreement is better in the extratropics than in the tropics. In the tropics multi-layer clouds and thin cirrus layers complicate the CTP retrieval, whereas good agreement is found for the cores of the deep convective system having a high optical depth. Furthermore, a good agreement between the algorithms is observed for trade wind cumulus and marine stratocumulus clouds. In the second part of the paper the SEVIRI retrievals are compared to CTH observations from the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) and Cloud Profiling Radar (CPR) instruments. It is important to note that the different measurement techniques cause differences in the retrieved CHT data. SEVIRI measures a radiatively effective CTH, while the CTH of the active instruments is derived from the return time of the emitted signal. Therefore some systematic diffrences are expected. On average the CTHs detected by the SEVIRI algorithms are 1.0 to 2.5 km lower than CALIOP observations, and the correlation coefficients between the SEVIRI and the CALIOP datasets range between 0.77 and 0.90. The mean CTH differences between the SEVIRI algorithms and CPR observations are smaller than for CALIOP ranging from -0.8 km to 0.6 km. The correlation coefficients of CPR and SEVIRI observations range between 0.82 and 0.89. To discuss the origin of the CTH deviation we elaborate the comparison for three cloud categories: optically thin and thick single layer as well as multi-layer clouds. For optically thick clouds the correlation coefficients between the SEVIRI and the reference datasets are usually above 0.95. For optically thin single layer clouds the correlation coefficients are still above 0.92. For this cloud category the SEVIRI algorithms yield CTHs that are lower than CALIOP but similar to CPR observations. Most challenging are the multi-layer clouds, where the correlation coefficients are for most algorithms between 0.6 and 0.8. Finally, we evaluate the performance of the SEVIRI retrievals for boundary layer clouds. While the CTH retrieval for this cloud type is relatively accurate, there are still considerable differences between the algorithms. These are related to uncertainties in and limited vertical resolution of the assumed temperature profiles in combination with the presence of temperature inversions, which lead to ambiguities in the CTH retrieval. Alternative approaches for the CTH retrieval of low clouds are discussed.

Hamann, U.; Walther, A.; Baum, B.; Bennartz, R.; Bugliaro, L.; Derrien, M.; Francis, P.; Heidinger, A.; Joro, S.; Kniffka, A.; Le Gléau, H.; Lockhoff, M.; Lutz, H.-J.; Meirink, J. F.; Minnis, P.; Palikonda, R.; Roebeling, R.; Thoss, A.; Platnick, S.; Watts, P.; Wind, G.

2014-01-01

46

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

47

Remote Sensing of Cloud Top Height from SEVIRI: Analysis of Eleven Current Retrieval Algorithms  

NASA Technical Reports Server (NTRS)

The role of clouds remains the largest uncertainty in climate projections. They influence solar and thermal radiative transfer and the earth's water cycle. Therefore, there is an urgent need for accurate cloud observations to validate climate models and to monitor climate change. Passive satellite imagers measuring radiation at visible to thermal infrared (IR) wavelengths provide a wealth of information on cloud properties. Among others, the cloud top height (CTH) - a crucial parameter to estimate the thermal cloud radiative forcing - can be retrieved. In this paper we investigate the skill of ten current retrieval algorithms to estimate the CTH using observations from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) onboard Meteosat Second Generation (MSG). In the first part we compare ten SEVIRI cloud top pressure (CTP) data sets with each other. The SEVIRI algorithms catch the latitudinal variation of the CTP in a similar way. The agreement is better in the extratropics than in the tropics. In the tropics multi-layer clouds and thin cirrus layers complicate the CTP retrieval, whereas a good agreement among the algorithms is found for trade wind cumulus, marine stratocumulus and the optically thick cores of the deep convective system. In the second part of the paper the SEVIRI retrievals are compared to CTH observations from the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) and Cloud Profiling Radar (CPR) instruments. It is important to note that the different measurement techniques cause differences in the retrieved CTH data. SEVIRI measures a radiatively effective CTH, while the CTH of the active instruments is derived from the return time of the emitted radar or lidar signal. Therefore, some systematic differences are expected. On average the CTHs detected by the SEVIRI algorithms are 1.0 to 2.5 kilometers lower than CALIOP observations, and the correlation coefficients between the SEVIRI and the CALIOP data sets range between 0.77 and 0.90. The average CTHs derived by the SEVIRI algorithms are closer to the CPR measurements than to CALIOP measurements. The biases between SEVIRI and CPR retrievals range from -0.8 kilometers to 0.6 kilometers. The correlation coefficients of CPR and SEVIRI observations vary between 0.82 and 0.89. To discuss the origin of the CTH deviation, we investigate three cloud categories: optically thin and thick single layer as well as multi-layer clouds. For optically thick clouds the correlation coefficients between the SEVIRI and the reference data sets are usually above 0.95. For optically thin single layer clouds the correlation coefficients are still above 0.92. For this cloud category the SEVIRI algorithms yield CTHs that are lower than CALIOP and similar to CPR observations. Most challenging are the multi-layer clouds, where the correlation coefficients are for most algorithms between 0.6 and 0.8. Finally, we evaluate the performance of the SEVIRI retrievals for boundary layer clouds. While the CTH retrieval for this cloud type is relatively accurate, there are still considerable differences between the algorithms. These are related to the uncertainties and limited vertical resolution of the assumed temperature profiles in combination with the presence of temperature inversions, which lead to ambiguities in the CTH retrieval. Alternative approaches for the CTH retrieval of low clouds are discussed.

Hamann, U.; Walther, A.; Baum, B.; Bennartz, R.; Bugliaro, L.; Derrien, M.; Francis, P. N.; Heidinger, A.; Joro, S.; Kniffka, A.; Le Gleau, H.; Lockhoff, M.; Lutz, H.-J.; Meirink, J. F.; Minnis, P.; Palikonda, R.; Roebeling, R.; Thoss, A.; Platnick, S.; Watts, P.; Wind, G.

2014-01-01

48

Remote sensing of cloud top pressure/height from SEVIRI: analysis of ten current retrieval algorithms  

NASA Astrophysics Data System (ADS)

The role of clouds remains the largest uncertainty in climate projections. They influence solar and thermal radiative transfer and the earth's water cycle. Therefore, there is an urgent need for accurate cloud observations to validate climate models and to monitor climate change. Passive satellite imagers measuring radiation at visible to thermal infrared (IR) wavelengths provide a wealth of information on cloud properties. Among others, the cloud top height (CTH) - a crucial parameter to estimate the thermal cloud radiative forcing - can be retrieved. In this paper we investigate the skill of ten current retrieval algorithms to estimate the CTH using observations from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) onboard Meteosat Second Generation (MSG). In the first part we compare ten SEVIRI cloud top pressure (CTP) data sets with each other. The SEVIRI algorithms catch the latitudinal variation of the CTP in a similar way. The agreement is better in the extratropics than in the tropics. In the tropics multi-layer clouds and thin cirrus layers complicate the CTP retrieval, whereas a good agreement among the algorithms is found for trade wind cumulus, marine stratocumulus and the optically thick cores of the deep convective system. In the second part of the paper the SEVIRI retrievals are compared to CTH observations from the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) and Cloud Profiling Radar (CPR) instruments. It is important to note that the different measurement techniques cause differences in the retrieved CTH data. SEVIRI measures a radiatively effective CTH, while the CTH of the active instruments is derived from the return time of the emitted radar or lidar signal. Therefore, some systematic differences are expected. On average the CTHs detected by the SEVIRI algorithms are 1.0 to 2.5 km lower than CALIOP observations, and the correlation coefficients between the SEVIRI and the CALIOP data sets range between 0.77 and 0.90. The average CTHs derived by the SEVIRI algorithms are closer to the CPR measurements than to CALIOP measurements. The biases between SEVIRI and CPR retrievals range from -0.8 km to 0.6 km. The correlation coefficients of CPR and SEVIRI observations vary between 0.82 and 0.89. To discuss the origin of the CTH deviation, we investigate three cloud categories: optically thin and thick single layer as well as multi-layer clouds. For optically thick clouds the correlation coefficients between the SEVIRI and the reference data sets are usually above 0.95. For optically thin single layer clouds the correlation coefficients are still above 0.92. For this cloud category the SEVIRI algorithms yield CTHs that are lower than CALIOP and similar to CPR observations. Most challenging are the multi-layer clouds, where the correlation coefficients are for most algorithms between 0.6 and 0.8. Finally, we evaluate the performance of the SEVIRI retrievals for boundary layer clouds. While the CTH retrieval for this cloud type is relatively accurate, there are still considerable differences between the algorithms. These are related to the uncertainties and limited vertical resolution of the assumed temperature profiles in combination with the presence of temperature inversions, which lead to ambiguities in the CTH retrieval. Alternative approaches for the CTH retrieval of low clouds are discussed.

Hamann, U.; Walther, A.; Baum, B.; Bennartz, R.; Bugliaro, L.; Derrien, M.; Francis, P. N.; Heidinger, A.; Joro, S.; Kniffka, A.; Le Gléau, H.; Lockhoff, M.; Lutz, H.-J.; Meirink, J. F.; Minnis, P.; Palikonda, R.; Roebeling, R.; Thoss, A.; Platnick, S.; Watts, P.; Wind, G.

2014-09-01

49

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

50

Lidar-based remote sensing of atmospheric boundary layer height over land and ocean  

NASA Astrophysics Data System (ADS)

Atmospheric boundary layer (ABL) processes are important in climate, weather and air quality. A better understanding of the structure and the behavior of the ABL is required for understanding and modeling of the chemistry and dynamics of the atmosphere on all scales. Based on the systematic variations of the ABL structures over different surfaces, different lidar-based methods were developed and evaluated to determine the boundary layer height and mixing layer height over land and ocean. With Atmospheric Radiation Measurement Program (ARM) Climate Research Facility (ACRF) micropulse lidar (MPL) and radiosonde measurements, diurnal and season cycles of atmospheric boundary layer depth and the ABL vertical structure over ocean and land are analyzed. The new methods are then applied to satellite lidar measurements. The aerosol-derived global marine boundary layer heights are evaluated with marine ABL stratiform cloud top heights and results show a good agreement between them.

Luo, T.; Yuan, R.; Wang, Z.

2014-01-01

51

GLITTER: New Lidar Technique for Cloud-Base Altimetry. Description and Initial Aircraft Measurements  

Microsoft Academic Search

Knowledge of cloud-base heights is important for climate studies, weather, and military operations. Conventional lidar methods monitor cloud depths by direct transmission of the beam through the cloud and sensing the backscattered returns. These techniques are limited by severe optical scattering by cloud particles to thickness < 0.5 km. We have conceived of a novel lidar method measurement for thick-cloud-base

Jerry A. Gelbwachs; Robert W. Farley

2004-01-01

52

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

53

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

NASA Astrophysics Data System (ADS)

The 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

54

Microprocessor-based ultrasonic height controller for sugarcane harvesters  

E-print Network

MICROPROCESSOR-BASED ULTRASONIC HEIGHT CONTROLLER FOR SUGARCANE HARVESTERS A Thesis by CRAIG ALLAN GOAD Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE... May 1980 Major Subject: Electrical Engineering MICROPROCESSOR-BASED ULTRASONIC HEIGHT CONTROLLER FOR SUGARCANE HARVESTERS A Thesis by CRAIG ALLAN GOAD Approved as to style and content by: V. T. Rhyne (Chairman of Committee) Charlie G. Coble...

Coad, Craig Allan

1980-01-01

55

Building outline detection based on height and intensity information of airborne laser scanning data  

NASA Astrophysics Data System (ADS)

Urban environment is extremely complex due to a multitude of features with different heights and structures. Traditional methods available to extract information regarding the buildings by using optical remote sensing images are highly labor-intensive and time-consuming. This paper developed a new method to detect building outlines based on height and intensity information of Airborne LiDAR data. Texture, relative height and intensity characteristics were first extracted from the LiDAR point cloud. Then, Support Vector Data Description was used to detect buildings with training knowledge. Finally, building outlines were obtained after data post process including small region removal, raster to vector conversion and so on. Experiments show the method proposed in this study is reliable and could be widely used in other urban areas.

Wang, Chengyi; Liang, Fuyuan; Zheng, Yi

2011-11-01

56

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

57

Relationship between cloud radiative forcing, cloud fraction and cloud albedo, and new surface-based approach for determining cloud albedo  

SciTech Connect

This paper focuses on three interconnected topics: (1) quantitative relationship between surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo; (2) surface-based approach for measuring cloud albedo; (3) multiscale (diurnal, annual and inter-annual) variations and covariations of surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo. An analytical expression is first derived to quantify the relationship between cloud radiative forcing, cloud fraction, and cloud albedo. The analytical expression is then used to deduce a new approach for inferring cloud albedo from concurrent surface-based measurements of downwelling surface shortwave radiation and cloud fraction. High-resolution decade-long data on cloud albedos are obtained by use of this surface-based approach over the US Department of Energy's Atmospheric Radiaton Measurement (ARM) Program at the Great Southern Plains (SGP) site. The surface-based cloud albedos are further compared against those derived from the coincident GOES satellite measurements. The three long-term (1997-2009) sets of hourly data on shortwave cloud radiative forcing, cloud fraction and cloud albedo collected over the SGP site are analyzed to explore the multiscale (diurnal, annual and inter-annual) variations and covariations. The analytical formulation is useful for diagnosing deficiencies of cloud-radiation parameterizations in climate models.

Liu, Y.; Wu, W.; Jensen, M. P.; Toto, T.

2011-07-21

58

Monitoring volcanic ash cloud top height through simultaneous retrieval of optical data from polar orbiting and geostationary satellites  

NASA Astrophysics Data System (ADS)

Volcanic ash cloud-top height (ACTH) can be monitored on the global level using satellite remote sensing. Here we propose a photogrammetric method based on the parallax between data retrieved from geostationary and polar orbiting satellites to overcome some limitations of the existing methods of ACTH retrieval. SEVIRI HRV band and MODIS band 1 are a good choice because of their high resolution. The procedure works well if the data from both satellites are retrieved nearly simultaneously. MODIS does not retrieve the data at exactly the same time as SEVIRI. To compensate for advection we use two sequential SEVIRI images (one before and one after the MODIS retrieval) and interpolate the cloud position from SEVIRI data to the time of MODIS retrieval. The proposed method was tested for the case of the Eyjafjallajökull eruption in April 2010. The parallax between MODIS and SEVIRI data can reach 30 km, which implies an ACTH of approximately 12 km at the beginning of the eruption. At the end of April eruption an ACTH of 3-4 km is observed. The accuracy of ACTH was estimated to be 0.6 km.

Zakšek, K.; Hort, M.; Zaletelj, J.; Langmann, B.

2013-03-01

59

Monitoring volcanic ash cloud top height through simultaneous retrieval of optical data from polar orbiting and geostationary satellites  

NASA Astrophysics Data System (ADS)

Volcanic ash cloud top height (ACTH) can be monitored on the global level using satellite remote sensing. Here we propose a photogrammetric method based on the parallax between data retrieved from geostationary and polar orbiting satellites to overcome some limitations of the existing methods of ACTH retrieval. SEVIRI HRV band and MODIS band 1 are a good choice because of their high resolution. The procedure works well if the data from both satellites are retrieved nearly simultaneously. MODIS does not retrieve the data at exactly the same time as SEVIRI. To compensate for advection we use two sequential SEVIRI images (one before and one after the MODIS retrieval) and interpolate the cloud position from SEVIRI data to the time of MODIS retrieval. The proposed method was tested for the case of the Eyjafjallajökull eruption in April 2010. The parallax between MODIS and SEVIRI data can reach over 30 km which implies ACTH of more than 12 km in the beginning of the eruption. In the end of April eruption ACTH of 3-4 km is observed. The accuracy of ACTH was estimated to be 0.6 km.

Zakšek, K.; Hort, M.; Zaletelj, J.; Langmann, B.

2012-09-01

60

A voxel-based lidar method for estimating crown base height for deciduous and pine trees  

E-print Network

A voxel-based lidar method for estimating crown base height for deciduous and pine trees Sorin C of this study was to develop methods for assessing crown base height for individual trees using airborne lidar) develop new lidar-derived features as multiband height bins and processing techniques for characterizing

61

Cloud Types  

NSDL National Science Digital Library

This table provides a quick reference to cloud types. Clouds are divided into groups mainly based on the height of the cloud's base above the Earth's surface. The table further divides the types according to group, atmospheric layer, and base height. Links to additional information are embedded in the text, and users can select beginner, intermediate, or advanced levels of difficulty. A Spanish translation is available.

62

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

63

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

64

Operational generation of AVHRR-based cloud products for Europe and the Arctic at EUMETSAT's Satellite Application Facility on Climate Monitoring (CM-SAF)  

NASA Astrophysics Data System (ADS)

The Satelite Application Facility on Climate Monitoring has implemented a new processing environment for AVHRR-based climate monitoring products. AVHRR measurements from NOAA-17, NOAA-18 and MetOp-A are utilized to generate daily and monthly means of several cloud parameters for Europe and the Inner Arctic: Cloud fraction, cloud types, cloud phase, cloud top height, cloud optical thickness and cloud liquid water path.

Kaspar, F.; Hollmann, R.; Lockhoff, M.; Karlsson, K.-G.; Dybbroe, A.; Fuchs, P.; Selbach, N.; Stein, D.; Schulz, J.

2009-04-01

65

Operational generation of AVHRR-based cloud products for Europe and the Arctic at EUMETSAT's Satellite Application Facility on Climate Monitoring (CM-SAF)  

Microsoft Academic Search

The Satelite Application Facility on Climate Monitoring has implemented a new processing environment for AVHRR-based climate monitoring products. AVHRR measurements from NOAA-17, NOAA-18 and MetOp-A are utilized to generate daily and monthly means of several cloud parameters for Europe and the Inner Arctic: Cloud fraction, cloud types, cloud phase, cloud top height, cloud optical thickness and cloud liquid water path.

F. Kaspar; R. Hollmann; M. Lockhoff; K.-G. Karlsson; A. Dybbroe; P. Fuchs; N. Selbach; D. Stein; J. Schulz

2009-01-01

66

IMPROVING A CLOUD MICROPHYSICS DATA ASSIMILATION TECHNIQUE USING CLOUD TOP HEIGHT INFORMATION ESTIMATED FROM THE OBSERVATION BY MULTI-FUNCTIONAL TRANSPORT SATELLITE  

NASA Astrophysics Data System (ADS)

To improve water vapor and cloud liquid water content in a numerical weather prediction model, Cloud Microphysics Data Assimilation System CMDAS) was developed. CMDAS improves an atmospheric condition by assimilating the brightness temperature data observed by the Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E). In the optimization scheme of CMDAS, a number of combinations of integrated water vapor and cloud water content are firstly given and those integrated values are vertically distributed depending on cloud top height (CTH). Using those vertical profiles, CMDAS searches the optimal atmospheric condition through a model operator and an observation operator. In the original CMDAS, a constant value is used as CTH. In this study, a horizontal distribution of CTH estimated from Multi-functional Transport Satellite (MTSAT)observation is applied to CMDAS and the effects of CTH information which is temporally and spatially consistent are examined.

Taniguchi, Kenji; Mirza, Cyrus Raza; Koike, Toshio

67

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

68

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

69

Satellite Remote Sensing of Mid-level Clouds  

E-print Network

This dissertation aims to study the mid-level clouds using satellite observations. It consists of two major parts: characteristics (including cloud top/base heights, cloud top pressure and temperature, and cloud thickness) and thermodynamic phase...

Jin, Hongchun 1980-

2012-11-07

70

MAXIMUM LIKELIHOOD ESTIMATION OF CLOUD HEIGHT FROM MULTI-ANGLE SATELLITE IMAGERY.  

E-print Network

on a two layer cloud ensemble where both layers are relatively planer, the bottom layer is optically thick and textured, and the top layer is optically thin. Our results demonstrate that with relative ease, we get in determining the Earth's energy budget. As a result, monitoring and characterizing the distribution of clouds

Yu, Bin

71

The effects of cloud inhomogeneities upon radiative fluxes, and the supply of a cloud truth validation dataset  

NASA Technical Reports Server (NTRS)

A series of cloud and sea ice retrieval algorithms are being developed in support of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Science Team objectives. These retrievals include the following: cloud fractional area, cloud optical thickness, cloud phase (water or ice), cloud particle effective radius, cloud top heights, cloud base height, cloud top temperature, cloud emissivity, cloud 3-D structure, cloud field scales of organization, sea ice fractional area, sea ice temperature, sea ice albedo, and sea surface temperature. Due to the problems of accurately retrieving cloud properties over bright surfaces, an advanced cloud classification method was developed which is based upon spectral and textural features and artificial intelligence classifiers.

Welch, Ronald M.

1993-01-01

72

An improved algorithm for polar cloud-base detection by ceilometer over the ice sheets  

NASA Astrophysics Data System (ADS)

Optically thin ice and mixed-phase clouds play an important role in polar regions due to their effect on cloud radiative impact and precipitation. Cloud-base heights can be detected by ceilometers, low-power backscatter lidars that run continuously and therefore have the potential to provide basic cloud statistics including cloud frequency, base height and vertical structure. The standard cloud-base detection algorithms of ceilometers are designed to detect optically thick liquid-containing clouds, while the detection of thin ice clouds requires an alternative approach. This paper presents the polar threshold (PT) algorithm that was developed to be sensitive to optically thin hydrometeor layers (minimum optical depth ? ≥ 0.01). The PT algorithm detects the first hydrometeor layer in a vertical attenuated backscatter profile exceeding a predefined threshold in combination with noise reduction and averaging procedures. The optimal backscatter threshold of 3 × 10-4 km-1 sr-1 for cloud-base detection near the surface was derived based on a sensitivity analysis using data from Princess Elisabeth, Antarctica and Summit, Greenland. At higher altitudes where the average noise level is higher than the backscatter threshold, the PT algorithm becomes signal-to-noise ratio driven. The algorithm defines cloudy conditions as any atmospheric profile containing a hydrometeor layer at least 90 m thick. A comparison with relative humidity measurements from radiosondes at Summit illustrates the algorithm's ability to significantly discriminate between clear-sky and cloudy conditions. Analysis of the cloud statistics derived from the PT algorithm indicates a year-round monthly mean cloud cover fraction of 72% (±10%) at Summit without a seasonal cycle. The occurrence of optically thick layers, indicating the presence of supercooled liquid water droplets, shows a seasonal cycle at Summit with a monthly mean summer peak of 40 % (±4%). The monthly mean cloud occurrence frequency in summer at Princess Elisabeth is 46% (±5%), which reduces to 12% (±2.5%) for supercooled liquid cloud layers. Our analyses furthermore illustrate the importance of optically thin hydrometeor layers located near the surface for both sites, with 87% of all detections below 500 m for Summit and 80% below 2 km for Princess Elisabeth. These results have implications for using satellite-based remotely sensed cloud observations, like CloudSat that may be insensitive for hydrometeors near the surface. The decrease of sensitivity with height, which is an inherent limitation of the ceilometer, does not have a significant impact on our results. This study highlights the potential of the PT algorithm to extract information in polar regions from various hydrometeor layers using measurements by the robust and relatively low-cost ceilometer instrument.

Van Tricht, K.; Gorodetskaya, I. V.; Lhermitte, S.; Turner, D. D.; Schween, J. H.; Van Lipzig, N. P. M.

2014-05-01

73

Relationship between cloud characteristics and radar reflectivity based on aircraft and cloud radar co-observations  

NASA Astrophysics Data System (ADS)

Cloud properties were investigated based on aircraft and cloud radar co-observation conducted at Yitong, Jilin, Northeast China. The aircraft provided in situ measurements of cloud droplet size distribution, while the millimeter-wavelength cloud radar vertically scanned the same cloud that the aircraft penetrated. The reflectivity factor calculated from aircraft measurements was compared in detail with simultaneous radar observations. The results showed that the two reflectivities were comparable in warm clouds, but in ice cloud there were more differences, which were probably associated with the occurrence of liquid water. The acceptable agreement between reflectivities obtained in water cloud confirmed that it is feasible to derive cloud properties by using aircraft data, and hence for cloud radar to remotely sense cloud properties. Based on the dataset collected in warm clouds, the threshold of reflectivity to diagnose drizzle and cloud particles was studied by analyses of the probability distribution function of reflectivity from cloud particles and drizzle drops. The relationship between reflectivity factor ( Z) and cloud liquid water content (LWC) was also derived from data on both cloud particles and drizzle. In comparison with cloud droplets, the relationship for drizzle was blurred by many scatter points and thus was less evident. However, these scatters could be partly removed by filtering out the drop size distribution with a large ratio of reflectivity and large extinction coefficient but small effective radius. Empirical relationships of Z-LWC for both cloud particles and drizzle could then be derived.

Zong, Rong; Liu, Liping; Yin, Yan

2013-09-01

74

The ESA Cloud CCI project: Generation of Multi Sensor consistent Cloud Properties with an Optimal Estimation Based Retrieval Algorithm  

NASA Astrophysics Data System (ADS)

The ultimate objective of the ESA Climate Change Initiative (CCI) Cloud project is to provide long-term coherent cloud property data sets exploiting and improving on the synergetic capabilities of past, existing, and upcoming European and American satellite missions. The synergetic approach allows not only for improved accuracy and extended temporal and spatial sampling of retrieved cloud properties better than those provided by single instruments alone but potentially also for improved (inter-)calibration and enhanced homogeneity and stability of the derived time series. Such advances are required by the scientific community to facilitate further progress in satellite-based climate monitoring, which leads to a better understanding of climate. Some of the primary objectives of ESA Cloud CCI Cloud are (1) the development of inter-calibrated radiance data sets, so called Fundamental Climate Data Records - for ESA and non ESA instruments through an international collaboration, (2) the development of an optimal estimation based retrieval framework for cloud related essential climate variables like cloud cover, cloud top height and temperature, liquid and ice water path, and (3) the development of two multi-annual global data sets for the mentioned cloud properties including uncertainty estimates. These two data sets are characterized by different combinations of satellite systems: the AVHRR heritage product comprising (A)ATSR, AVHRR and MODIS and the novel (A)ATSR - MERIS product which is based on a synergetic retrieval using both instruments. Both datasets cover the years 2007-2009 in the first project phase. ESA Cloud CCI will also carry out a comprehensive validation of the cloud property products and provide a common data base as in the framework of the Global Energy and Water Cycle Experiment (GEWEX). The presentation will give an overview of the ESA Cloud CCI project and its goals and approaches and then continue with results from the Round Robin algorithm comparison exercise carried out at the beginning of the project which included three algorithms. The purpose of the exercise was to assess and compare existing cloud retrieval algorithms in order to chose one of them as backbone of the retrieval system and also identify areas of potential improvement and general strengths and weaknesses of the algorithm. Furthermore the presentation will elaborate on the optimal estimation algorithm subsequently chosen to derive the heritage product and which is presently further developed and will be employed for the AVHRR heritage product. The algorithm's capabilities to coherently and simultaneously process all radiative input and yield retrieval parameters together with associated uncertainty estimates will be presented together with first results for the heritage product. In the course of the project the algorithm is being developed into a freely and publicly available community retrieval system for interested scientists.

Jerg, M.; Stengel, M.; Hollmann, R.; Poulsen, C.

2012-04-01

75

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

E-print Network

for Internet applications developers. Previously, a main concern of Internet applications developers]. Along with the advancements of the Cloud technology, new possibilities for Internet-based applications popularity on the Internet. These applications can benefit greatly of Cloud infrastructure services

Buyya, Rajkumar

76

Biological ice nuclei at tropospheric cloud heights: potential conditioning of precipitation  

NASA Astrophysics Data System (ADS)

Different substances present in the atmosphere enhance the aggregation of water molecules into ice structures, but particularly effective seem to be aerosols of biological origin, active at temperatures up to -2°C. Yet, the relevance of biological ice nucleation for cloud processes, such as initiating precipitation, remains ambiguous. We try to understand the meteorological conditions and the environmental factors controlling the abundance of biological ice nuclei (IN) in precipitation. One full year of observations has been carried out at the High Altitude Research station of Jungfraujoch, in the Swiss Alps, 3580 m a.s.l. Fresh snow was collected each month and analysed immediately on site for the concentration of IN active at temperatures warmer than -12°C. For this purpose we had developed an innovative system automatically recording freezing events of samples in closed tubes. Additional information was gained through the recording of meteorological parameters associated with the precipitation events, and the determination of stable isotopes (2H and 18O) and of bacterial concentrations (direct epifluorescence microscope counting, live/dead staining) in precipitation. Our analysis of the data suggests that the abundance of ice nuclei in snowfall is characterized not only by seasonality, but also by the geographical origin of precipitating air masses. Further, it seems that the more water an air mass has lost through previous precipitation, the smaller is the biological IN abundance in the remaining precipitation. Moreover, the loss of biological IN with precipitation seems to be much faster than that of other suspended particles in the same air mass, pointing towards a role of biological IN in conditioning the development of precipitation at its early stages.

Stopelli, Emiliano; Conen, Franz; Alewell, Christine; Morris, Cindy

2014-05-01

77

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.

2012-08-03

78

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

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

Estimation of Biomass Potential Based on Classification and Height Information  

NASA Astrophysics Data System (ADS)

On the way to make energy supply independent from fossil resources more and more renewable energy sources have to be explored. Biomass has become an important energy resource during the last years and the consumption is rising steadily. Common sources of biomass are agricultural production and forestry but the production of these sources is stagnating due to limited space. To explore new sources of biomass like in the field of landscape conservation the location and available amount of biomass is unknown. Normally, there are no reliable data sources to give information about the objects of interest such as hedges, vegetation along streets, railways and rivers, field margins and ruderal sites. There is a great demand for an inventory of these biomass sources which could be answered by applying remote sensing technology. As biomass objects considered here are sometimes only a few meters wide, spectral unmixing is applied to separate different material mixtures reflected in one image pixel. The spectral images are assumed to have a spatial resolution of 5-20 m with multispectral or hyperspectral band configurations. Combining the identified material part fractions with height information and GIS data afterwards will give estimates about the location of biomass objects. The method is applied to test data of a Sentinel-2 simulation and the results are evaluated visually.

Müller, S.; Büscher, O.; Jandewerth, M.

2013-05-01

81

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

82

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

83

Comparing the Cloud Vertical Structure Derived from Several Methods Based on Radiosonde Profiles and Ground-based Remote Sensing Measurements  

SciTech Connect

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-Suros, M.; Calbo, J.; Gonzalez, J. A.; Long, Charles N.

2014-08-27

84

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 this purpose, a SICKÃ? LMS 291 LIght Detection And Ranging (LIDAR) unit was evaluated in static and dynamic mode

85

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

E-print Network

algorithm becomes problematic due to the relatively weak cloud signal-to-noise ratio in the thermal infrared Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) measurements. By investigating the spatial

Baum, Bryan A.

86

Target height finding in narrowband ground-based 3D surveillance radar using beamspace approach  

Microsoft Academic Search

In this paper, a novel target height finding method based on the robust beamspace transformation is proposed in ground-based air-surveillance radar applications. Compared with the conventional multipath height finding techniques, all diffuse reflected multipath signals are considered as the interference signals and cancelled via beamspace transformation in our method. Measured data from an experimental 3D air-surveillance radar are used to

Ting Shu; Xingzhao Liu; Wenxian Yu

2009-01-01

87

NIR: Content based image retrieval on cloud computing  

Microsoft Academic Search

NIR is an open source cloud computing enabled content based image retrieval system. With the development and popularization of cloud computing, more and more researchers from different research areas do research with the help of cloud computing. Nowadays content based image retrieval as one of the challenging and emerging technologies is high computation task because of the algorithm computation complexity

Zhuo Yang; Sei-ichiro KAMATA; Alireza AHRARY

2009-01-01

88

Height Compensation Using Ground Inclination Estimation in Inertial Sensor-Based Pedestrian Navigation  

PubMed Central

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

89

Ontology-Based Resource Management for Cloud Computing  

Microsoft Academic Search

\\u000a Resource management is a challenging issue in cloud computing. This paper aims to allocate requested jobs to cloud resources\\u000a suitable for cloud user requirements. To achieve the aim, this paper proposes an ontology-based job allocation algorithm for\\u000a cloud computing to perform inferences based on semantic meanings. We extract resource candidates depending on user requirements\\u000a and allocate a job to the

Yong Beom Ma; Sung-Ho Jang; Jong Sik Lee

2011-01-01

90

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

NASA Astrophysics Data System (ADS)

Ground-based 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

91

NASA Cloud-Based Climate Data Services  

NASA Astrophysics Data System (ADS)

Cloud-based scientific data services are becoming an important part of NASA's mission. Our technological response is built around the concept of specialized virtual climate data servers, repetitive cloud provisioning, image-based deployment and distribution, and virtualization-as-a-service (VaaS). A virtual climate data server (vCDS) is an Open Archive Information System (OAIS) compliant, iRODS-based data server designed to support a particular type of scientific data collection. iRODS is data grid middleware that provides policy-based control over collection-building, managing, querying, accessing, and preserving large scientific data sets. We have deployed vCDS Version 1.0 in the Amazon EC2 cloud using S3 object storage and are using the system to deliver a subset of NASA's Intergovernmental Panel on Climate Change (IPCC) data products to the latest CentOS federated version of Earth System Grid Federation (ESGF), which is also running in the Amazon cloud. vCDS-managed objects are exposed to ESGF through FUSE (Filesystem in User Space), which presents a POSIX-compliant filesystem abstraction to applications such as the ESGF server that require such an interface. A vCDS manages data as a distinguished collection for a person, project, lab, or other logical unit. A vCDS can manage a collection across multiple storage resources using rules and microservices to enforce collection policies. And a vCDS can federate with other vCDSs to manage multiple collections over multiple resources, thereby creating what can be thought of as an ecosystem of managed collections. With the vCDS approach, we are trying to enable the full information lifecycle management of scientific data collections and make tractable the task of providing diverse climate data services. In this presentation, we describe our approach, experiences, lessons learned, and plans for the future.; (A) vCDS/ESG system stack. (B) Conceptual architecture for NASA cloud-based data services.

McInerney, M. A.; Schnase, J. L.; Duffy, D. Q.; Tamkin, G. S.; Strong, S.; Ripley, W. D., III; Thompson, J. H.; Gill, R.; Jasen, J. E.; Samowich, B.; Pobre, Z.; Salmon, E. M.; Rumney, G.; Schardt, T. D.

2012-12-01

92

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

93

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

94

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

95

A Statistical Model of Cloud Vertical Structure Based on Reconciling Cloud Layer Amounts Inferred from  

E-print Network

A Statistical Model of Cloud Vertical Structure Based on Reconciling Cloud Layer Amounts Inferred at the same scales of variation. In particular, not only the magnitude of these changes must be quantified base pressures that are quantitatively closer to observations based on surface weather observations

Wang, Junhong

96

Effective pollutant emission heights for atmospheric transport modelling based on real-world information.  

PubMed

Emission data needed as input for the operation of atmospheric models should not only be spatially and temporally resolved. Another important feature is the effective emission height which significantly influences modelled concentration values. Unfortunately this information, which is especially relevant for large point sources, is usually not available and simple assumptions are often used in atmospheric models. As a contribution to improve knowledge on emission heights this paper provides typical default values for the driving parameters stack height and flue gas temperature, velocity and flow rate for different industrial sources. The results were derived from an analysis of the probably most comprehensive database of real-world stack information existing in Europe based on German industrial data. A bottom-up calculation of effective emission heights applying equations used for Gaussian dispersion models shows significant differences depending on source and air pollutant and compared to approaches currently used for atmospheric transport modelling. PMID:18952331

Pregger, Thomas; Friedrich, Rainer

2009-02-01

97

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

98

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

99

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

100

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

Microsoft Academic Search

In recent years, the use of airborne lidar technology to measure forest biophysical characteristics has been rapidly increasing. This paper discusses processing algorithms for deriving the terrain model and estimating tree heights by using a multiple return, high–density, small-footprint lidar data set. The lidar data were acquired over deciduous, coniferous, and mixed stands of varying age classes and settings typical

Sorin C. Popescu; Randolph H. Wynne; Ross F. Nelson

2002-01-01

101

Stereoscopic Retrieval of Smoke Plume Heights and Motion from Space-Based Multi-Angle Imaging, Using the MISR INteractive eXplorer(MINX)  

NASA Technical Reports Server (NTRS)

Airborne particles desert dust, wildfire smoke, volcanic effluent, urban pollution affect Earth's climate as well as air quality and health. They are found in the atmosphere all over the planet, but vary immensely in amount and properties with season and location. Most aerosol particles are injected into the near-surface boundary layer, but some, especially wildfire smoke, desert dust and volcanic ash, can be injected higher into the atmosphere, where they can stay aloft longer, travel farther, produce larger climate effects, and possibly affect human and ecosystem health far downwind. So monitoring aerosol injection height globally can make important contributions to climate science and air quality studies. The Multi-angle Imaging Spectro-Radiometer (MISR) is a space borne instrument designed to study Earths clouds, aerosols, and surface. Since late February 2000 it has been retrieving aerosol particle amount and properties, as well as cloud height and wind data, globally, about once per week. The MINX visualization and analysis tool complements the operational MISR data products, enabling users to retrieve heights and winds locally for detailed studies of smoke plumes, at higher spatial resolution and with greater precision than the operational product and other space-based, passive remote sensing techniques. MINX software is being used to provide plume height statistics for climatological studies as well as to investigate the dynamics of individual plumes, and to provide parameterizations for climate modeling.

Nelson, David L.; Kahn, Ralph A.

2014-01-01

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

Comparative evaluation of hemodynamic and respiratory parameters during mechanical ventilation with two tidal volumes calculated by demi-span based height and measured height in normal lungs  

PubMed Central

Background: Appropriate determination of tidal volume (VT) is important for preventing ventilation induced lung injury. We compared hemodynamic and respiratory parameters in two conditions of receiving VTs calculated by using body weight (BW), which was estimated by measured height (HBW) or demi-span based body weight (DBW). Materials and Methods: This controlled-trial was conducted in St. Alzahra Hospital in 2009 on American Society of Anesthesiologists (ASA) I and II, 18-65-years-old patients. Standing height and weight were measured and then height was calculated using demi-span method. BW and VT were calculated with acute respiratory distress syndrome-net formula. Patients were randomized and then crossed to receive ventilation with both calculated VTs for 20 min. Hemodynamic and respiratory parameters were analyzed with SPSS version 20.0 using univariate and multivariate analyses. Results: Forty nine patients were studied. Demi-span based body weight and thus VT (DTV) were lower than Height based body weight and VT (HTV) (P = 0.028), in male patients (P = 0.005). Difference was observed in peak airway pressure (PAP) and airway resistance (AR) changes with higher PAP and AR at 20 min after receiving HTV compared with DTV. Conclusions: Estimated VT based on measured height is higher than that based on demi-span and this difference exists only in females, and this higher VT results higher airway pressures during mechanical ventilation. PMID:24627845

Seresht, L. Mousavi; Golparvar, Mohammad; Yaraghi, Ahmad

2014-01-01

104

Comparison of the CALIPSO satellite and ground-based observations of cirrus clouds at the ARM TWP sites  

NASA Astrophysics Data System (ADS)

Statistics of ice cloud macrophysical and optical properties from the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) instrument on board the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite are compared with those from ground-based lidar observations over a 31 month period. Ground-based lidar observations are taken from the micropulse lidars (MPL) at the three Department of Energy Atmospheric Radiation Measurement (ARM) tropical western pacific (TWP) sites: Manus, Nauru and Darwin. CALIPSO observations show a larger cloud fraction at high altitudes while the ground-based MPLs show a larger cloud fraction at low altitudes. The difference in mean ice cloud top and base heights at the Manus and Nauru sites are all within 0.51 km, although differences are statistically significant. Mean ice cloud geometrical thickness agree to within 0.05 km at the Manus and Nauru sites. Larger differences exist at Darwin due to excessive degradation of the MPL output power during our sampling period. Both sets of observations show thicker clouds during the nighttime which may be real but could also be partially an artifact of the decreased signal-to-noise ratio during the daytime. The number of ice cloud layers per profile are also shown to be consistent after accounting for the difference in spatial resolution. For cloud optical depths, four different retrieval methods are compared, two for each set of observations. All products show that the majority of ice cloud optical depths (˜60%) fall below an optical depth of 0.2. For most comparisons all four retrievals agree to within the uncertainty intervals. We find that both CALIPSO retrievals agree best to ground-based optical depths when the lidar ratio in the latter is retrieved instead of set to a fixed value. Also thoroughly compared is the cloud properties for the subset of ice clouds which reside in the tropical tropopause layer (TTL).

Thorsen, Tyler J.; Fu, Qiang; Comstock, Jennifer

2011-11-01

105

Comparison of the CALIPSO satellite and ground-based observations of cirrus clouds at the ARM TWP sites  

SciTech Connect

Statistics of ice cloud macrophysical and optical properties from the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) instrument on board the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite are compared with those from ground-based lidar observations over a 31 month period. Ground-based lidar observations are taken from the micropulse lidars (MPL) at the three Department of Energy Atmospheric Radiation Measurement (ARM) tropical western pacific (TWP) sites: Manus, Nauru and Darwin. CALIPSO observations show a larger cloud fraction at high altitudes while the ground-based MPLs show a larger cloud fraction at low altitudes. The difference in mean ice cloud top and base heights at the Manus and Nauru sites are all within 0.51 km, although differences are statistically significant. Mean ice cloud geometrical thickness agree to within 0.05 km at the Manus and Nauru sites. Larger differences exist at Darwin due to excessive degradation of the MPL output power during our sampling period. Both sets of observations show thicker clouds during the nighttime which may be real but could also be partially an artifact of the decreased signal-to-noise ratio during the daytime. The number of ice cloud layers per profile are also shown to be consistent after accounting for the difference in spatial resolution. For cloud optical depths, four different retrieval methods are compared, two for each set of observations. All products show that the majority of ice cloud optical depths ({approx}60%) fall below an optical depth of 0.2. For most comparisons all four retrievals agree to within the uncertainty intervals. We find that both CALIPSO retrievals agree best to ground-based optical depths when the lidar ratio in the latter is retrieved instead of set to a fixed value. Also thoroughly compared is the cloud properties for the subset of ice clouds which reside in the tropical tropopause layer (TTL).

Thorsen, Tyler J.; Fu, Q.; Comstock, Jennifer M.

2011-11-10

106

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

107

STUDY OF GRIDDED MIXING HEIGHTS AD CLOUD FIELDS DERIVED FROM THE MESOSCALE METEOROLOGICAL MODEL WITH FOUR DIMENSIONAL DATA ASSIMILATION  

EPA Science Inventory

Meteorological data including wind, temperature and moisture variables, as well as boundary layer parameters including surface fluxes, depth of the mixed layer and cloud and precipitation information are integral components of air quality simulations models (AQSMS). QSMs require ...

108

Comparing the cloud vertical structure derived from several methods based on radiosonde profiles and ground-based remote sensing measurements  

NASA Astrophysics Data System (ADS)

The cloud vertical distribution and especially the cloud base height, which is linked to cloud type, are important characteristics in order to describe the impact of clouds on climate. In this work, several methods for estimating the cloud vertical structure (CVS) based on atmospheric sounding profiles are compared, considering the number and position of cloud layers, with a ground-based system that is taken as a reference: the Active Remote Sensing of Clouds (ARSCL). All methods establish some conditions on the relative humidity, and differ in 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 Atmospheric Radiation Measurement (ARM) Southern Great Plains site during all seasons of the year 2009 and endorsed by Geostationary Operational Environmental Satellite (GOES) images, to confirm that the cloudiness conditions are homogeneous enough across their trajectory. The perfect agreement (i.e., when the whole CVS is estimated correctly) for the methods ranges between 26 and 64%; the methods show additional approximate agreement (i.e., when at least one cloud layer is assessed correctly) from 15 to 41%. Further tests and improvements are applied to 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 World Meteorological Organization's (WMO) Global Telecommunication System. The perfect agreement, even when using low-resolution profiles, can be improved by up to 67% (plus 25% of the 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.

2014-08-01

109

Cloud computing infrastructure based on named content  

Microsoft Academic Search

Cloud computing is a trend which facilitates the development of the distributed applications and reduces the cost of the deployments, and it has impacted the IT industry a lot. Cloud computing depends a lot on the characteristics of the network, as the remote processing and large data center are vital for cloud computing. And the evolution of the networks will

Junjie Tong; Renjie Pi; Ke Xu

2011-01-01

110

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

111

Effect of aberration on height calibration in three-dimensional localization-based  

E-print Network

of out-of-focus light with a pinhole, termed confocal microscopy [1], using nonlinearitiesEffect of aberration on height calibration in three-dimensional localization-based microscopy, aberrations will change the relationship between the image width and the axial position. We analyzed the depth

Petta, Jason

112

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

113

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.

114

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

115

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.

116

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

117

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

118

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.

Carl Wozniak

119

Retrievals of Cloud Fraction and Cloud Albedo from Surface-based Shortwave Radiation Measurements: A Comparison of 16 Year Measurements  

SciTech Connect

Ground-based radiation measurements have been widely conducted to gain information on clouds and the surface radiation budget; here several different techniques for retrieving cloud fraction (Long2006, Min2008 and XL2013) and cloud albedo (Min2008, Liu2011 and XL2013) from ground-based shortwave broadband and spectral radiation measurements are examined, and sixteen years of retrievals collected at the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site are compared. 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 retrieval of cloud albedo tends to be greater for thin clouds but smaller for thick clouds, with the differences decreasing with increasing cloud fraction. 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. Potential influences of cloud absorption, land-surface albedo, cloud structure, and measurement instruments are explored.

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

2014-07-27

120

Testing the Parameterizations of Cloud Base Mass-Flux for Shallow Cumulus Clouds using Cloud Radar Observations  

NASA Astrophysics Data System (ADS)

Shallow cumulus clouds have significant impact on the vertical distributions of heat and moisture and on surface energy fluxes over land through their effect on incoming shortwave radiation. The present resolutions of General Circulation Model (GCM) and Numerical weather prediction (NWP) models are not fine enough to simulate shallow clouds directly, leaving not much choice other than parameterizations evaluated using either Large Eddy Simulation (LES) and observations. The representation of these clouds in numerical models is an important and challenging issue in model development, because of its potential impacts on near-surface weather and long-term climate simulations. Recent studies through LES have shown that the mass flux is the important parameter for determining the characteristics of cumulus transports within cloud layer. Based on LES results and scaling arguments, substantial efforts have been made to parameterize the cloud base mass flux to improve the interactions between the subcloud and cloud layer. Despite these efforts, what factors control the mass flux and how the interaction between subcloud and cloud layers should be parameterized is not fully understood. From the observational perspective, studies have been done using aircraft and remote sensing platform to address the above issue; there have been insufficient observations to develop detailed composite studies under different conditions. The Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) in Southern Great Plains (SGP) offers unique long-term measurements from cloud radars (35 and 94 GHz) along with synergetic measurements to address the above problem of non-precipitating shallow cumulus clouds over the SGP region. Doppler velocities from the cloud radar are processed to remove the insect contamination using a fuzzy-logic approach before they are used for the mass-flux calculation. The present observations are used to validate the existing mass-flux relations used in parameterizations. The possible factors [such as, effect of wind shear, transition layer strength, lower tropospheric relative humidity, large-scale vertical velocity and stability (CAPE and CIN)] that affects the mass-flux in addition to the convective velocity (w*) are studied using sounding and ECMWF model dataset. Furthermore, the data are classified based on time of the day, and for various cloud fractions and composite profiles are calculated to define the differences for different regimes.

Chandra, A.; Kollias, P.; Albrecht, B. A.; Zhu, P.; Klein, S. A.; Zhang, Y.

2010-12-01

121

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

122

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

123

INFLUENCE ON HEIGHT MEASURE FROM EARTH CURVATURE BASED ON SPACEBORNE INSAR  

Microsoft Academic Search

It is very different from spaceborne InSAR and airborne InS AR because satellite orbit is relatively more higher, the distance between satellite subsatellite point and mapping area may be from hundreds to thousands of kilometers. Height measure based on spaceborne InSAR must eliminate the influence of earth's curvature, otherwise its error may be higher. But how much is the influence

Tang Xiaotao; Niu Rui; Chen Gang; Liu Zhiming

124

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

125

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

E-print Network

--Advances in Cloud computing enable new possibilities to Internet applications developers. Previously, the main concern of Internet applications developers was deployment and hosting of applications, because for Internet-based applications development are emerging. These new application models are based in two parties

Melbourne, University of

126

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

127

Clouds: An Internet Based Lesson Plan  

NSDL National Science Digital Library

This site facilitates a classroom activity in which students create a hypothesis on cloud formation and then conduct online research to either validate or refute their initial hypothesis. The activity begins with a brief laboratory experiment that demonstrates cloud formation and asks students to generate a hypothesis on how clouds form. The activity then switches to students conducting Internet research. Finally, small groups of students will create reports summarizing the cloud formation process, and each group will present their report to the class. Students are then encouraged to compare their final reports with the initial hypothesis created by the class. Students can also track and research local weather patterns, and study how technology is utilized in predicting weather.

Jack Hassard

128

Interactive physically-based cloud simulation  

E-print Network

Clouds play an important role in the depiction of many natural outdoor scenes. Realistic modeling and rendering of such scenes is important for applications in games, military training simulations, flight simulations, and even in the creation...

Overby, Derek Robert

2002-01-01

129

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

130

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

131

Pixel-based approach for building heights determination by SAR radargrammetry  

NASA Astrophysics Data System (ADS)

Numerous advances have been made recently in photogrammetry, laser scanning, and remote sensing for the creation of 3D city models. More and more cities are interested in getting 3D city models, be it for urban planning purposes or for supporting public utility companies. In areas often affected by natural disaster, rapid updating of the 3D information may also be useful for helping rescue forces. The high resolutions that can be achieved by the new spaceborne SAR sensor generation enables the analysis of city areas at building level and make those sensors attractive for the extraction of 3D information. Moreover, they present the advantage of weather and sunlight independency, which make them more practicable than optical data, in particular for tasks where rapid response is required. Furthermore, their short revisit time and the possibility of multi-sensor constellation enable providing several acquisitions within a few hours. This opens up the floor for new applications, especially radargrammetric applications, which consider acquisitions taken under different incidence angles. In this paper, we present a new approach for determining building heights, relying only on the radargrammetric analysis of building layover. By taking into account same-side acquisitions, we present the workflow of building height determination. Focus is set on some geometric considerations, pixel-based approach for disparity map calculation, and analysis of the building layover signature for different configurations in order to determine building height.

Dubois, C.; Thiele, A.; Hinz, S.

2013-10-01

132

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

133

Clouds  

NSDL National Science Digital Library

First, the Project Atmosphere Canada offers a module to educate primary and secondary students about cloud formation and characteristics (1). The website outlines key points and offers a more in-depth discussion of water vapor, cloud formation, convection, air motion, severe weather, and more. The second website, by Scholastic, supplies many pdf documents of activities and lesson plans for all types of weather phenomena including clouds (2). Students can learn about condensation, discover what makes up a cloud, and find a key identifying the cloud types. Next, USA Today offers an online tutorial of the differing characteristics of clouds (3). Users can learn about Mammatus clouds, contrails, cloud seeding, and other cloud-related topics. At the fourth website, visitors can view meteorologist Dan Satterfield's amazing cloud photographs (4). Educators may find useful materials to supplement their lectures. Next, NASA's Climate and Radiation Branch furnishes "information on the fantastic variety of cloud forms and structures, and their implications for climate" (5). While the website is still being constructed, users can find useful information about the Bounded Cascades Fractal Cloud model, animations, and definitions of inhomogeneous cloud terminology. The sixth website, created by the National Center for Atmospheric Research and the University Corporation for Atmospheric Research, addresses how clouds impact our lives, how they cause chaos, and how they form (6). The enlightening descriptions are packed with colorful images and short quizzes. Next, The Australian Government's Bureau of Meteorology describes the useful of clouds as an indicator of weather conditions (7). After learning how moist air can form clouds, individuals can view images of the ten most common cloud types. Lastly, Enchanted Learning offers a table of the cloud types with their abbreviation, appearance, composition, and altitude along with explanations of cloud formation and the atmosphere (8). Educators can find simple activities dealing with cloud types and the water cycle.

134

pCloud: A Cloud-based Power Market Simulation Environment  

SciTech Connect

This research conducted by the Newton Energy Group, LLC (NEG) is dedicated to the development of pCloud: a Cloud-based Power Market Simulation Environment. pCloud is offering power industry stakeholders the capability to model electricity markets and is organized around the Software as a Service (SaaS) concept -- a software application delivery model in which software is centrally hosted and provided to many users via the internet. During the Phase I of this project NEG developed a prototype design for pCloud as a SaaS-based commercial service offering, system architecture supporting that design, ensured feasibility of key architecture's elements, formed technological partnerships and negotiated commercial agreements with partners, conducted market research and other related activities and secured funding for continue development of pCloud between the end of Phase I and beginning of Phase II, if awarded. Based on the results of Phase I activities, NEG has established that the development of a cloud-based power market simulation environment within the Windows Azure platform is technologically feasible, can be accomplished within the budget and timeframe available through the Phase II SBIR award with additional external funding. NEG believes that pCloud has the potential to become a game-changing technology for the modeling and analysis of electricity markets. This potential is due to the following critical advantages of pCloud over its competition: - Standardized access to advanced and proven power market simulators offered by third parties. - Automated parallelization of simulations and dynamic provisioning of computing resources on the cloud. This combination of automation and scalability dramatically reduces turn-around time while offering the capability to increase the number of analyzed scenarios by a factor of 10, 100 or even 1000. - Access to ready-to-use data and to cloud-based resources leading to a reduction in software, hardware, and IT costs. - Competitive pricing structure, which will make high-volume usage of simulation services affordable. - Availability and affordability of high quality power simulators, which presently only large corporate clients can afford, will level the playing field in developing regional energy policies, determining prudent cost recovery mechanisms and assuring just and reasonable rates to consumers. - Users that presently do not have the resources to internally maintain modeling capabilities will now be able to run simulations. This will invite more players into the industry, ultimately leading to more transparent and liquid power markets.

Rudkevich, Aleksandr; Goldis, Evgeniy

2012-12-02

135

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

E-print Network

--Advances in Cloud computing opens up many new possibilities to Internet applications developers. Previously, a main concern of Internet applications developers was deployment and hosting of applications, because for Internet-based applications development are emerging. These new application models can be grouped in to two

Calheiros, Rodrigo N.

136

Low Clouds  

Atmospheric Science Data Center

... and reddening of the hues in the foreground. Stereoscopic analysis of the data from multiple MISR cameras indicates that the cloud tops ... formats available at JPL July 23, 2007 - Trend of decreasing global cloud height during the last decade. ...

2013-04-19

137

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

138

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

139

ESA Cloud CCI: Generation of optimal estimation based, multi-sensor cloud property data set from AVHRR heritage measurements.  

NASA Astrophysics Data System (ADS)

In 2010 the ESA Climate Change Initiative (CCI) Cloud project was started with the objectives of generating long-term coherent data set of cloud properties. The cloud properties considered are cloud mask, cloud top estimates, cloud optical thickness, cloud effective radius and post processed parameters such as cloud liquid and ice water path. These data records are based on an optimal estimation (OE) retrieval and which enables the application to multiple sensors of past, existing, and upcoming European and Non-European satellite missions. The multi-sensor based datasets are characterized by high temporal and spatial samplings, high accuracy, homogeneity and stability. The OE approach further allows for a simultaneous, coherent and spectrally consistent retrieval of all cloud properties together with a provision of physically-derived, pixel-based uncertainty estimates for each cloud property. In the first project phase, two multi-annual datasets spanning 2007 to 2009 and based on carefully (inter-)calibrated radiances will be provided. The AVHRR-heritage dataset includes the sensors AVHRR, AATSR and MODIS. The synergy dataset is based on combined AATSR and MERIS measurements. Within the second phase of the project all datasets will be extended to the full lengths of the measurements records resulting in multi-decadal Fundamental Climate Data Records. The presentation will give an overview of the CCI Cloud project, its objectives, timeline and progress. The datasets and their characteristics will be introduced, examples presented and evaluations against other satellite- and ground-based data presented.

Stapelberg, Stefan; Jerg, Matthias; Stengel, Martin; Hollmann, Rainer; Lindstrot, Rasmus; Poulsen, Caroline; Esa Cloud CCI Team

2013-04-01

140

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

141

Clouds  

NSDL National Science Digital Library

Students learn about the varieties of clouds, what they look like and how they can affect our lives. Introduction: Have you ever wondered what kind of cloud makes rain, or which one makes fog? Have you ever wondered if there are clouds that mean the weather if going to be good or not? Today, we're going to learn about three different clouds that may ...

Ms. Doxey

2010-03-26

142

Gas cloud infrared image enhancement based on anisotropic diffusion  

NASA Astrophysics Data System (ADS)

Leakage of dangerous gases will not only pollute the environment, but also seriously threat public safety. Thermal infrared imaging has been proved to be an efficient method to qualitatively detect the gas leakage. But some problems are remained, especially when monitoring the leakage in a passive way. For example, the signal is weak and the edge of gas cloud in the infrared image is not obvious enough. However, we notice some important characteristics of the gas plume and therefore propose a gas cloud infrared image enhancement method based on anisotropic diffusion. As the gas plume presents a large gas cloud in the image and the gray value is even inside the cloud, strong forward diffusion will be used to reduce the noise and to expand the range of the gas cloud. Frames subtraction and K-means cluttering pop out the gas cloud area. Forward-and-Backward diffusion is to protect background details. Additionally, the best iteration times and the time step parameters are researched. Results show that the gas cloud can be marked correctly and enhanced by black or false color, and so potentially increase the possibility of gas leakage detection.

Li, Jiakun; Wang, Lingxue; Zhang, Changxing; Long, Yunting; Zhang, Bei

2011-05-01

143

The effect of clouds on the earth's radiation budget  

NASA Technical Reports Server (NTRS)

The radiative fluxes from the Earth Radiation Budget Experiment (ERBE) and the cloud properties from the International Satellite Cloud Climatology Project (ISCCP) over Indonesia for the months of June and July of 1985 and 1986 were analyzed to determine the cloud sensitivity coefficients. The method involved a linear least squares regression between co-incident flux and cloud coverage measurements. The calculated slope is identified as the cloud sensitivity. It was found that the correlations between the total cloud fraction and radiation parameters were modest. However, correlations between cloud fraction and IR flux were improved by separating clouds by height. Likewise, correlations between the visible flux and cloud fractions were improved by distinguishing clouds based on optical depth. Calculating correlations between the net fluxes and either height or optical depth segregated cloud fractions were somewhat improved. When clouds were classified in terms of their height and optical depth, correlations among all the radiation components were improved. Mean cloud sensitivities based on the regression of radiative fluxes against height and optical depth separated cloud types are presented. Results are compared to a one-dimensional radiation model with a simple cloud parameterization scheme.

Ziskin, Daniel; Strobel, Darrell F.

1991-01-01

144

Observations of the Interaction of Aerosols with Cloud or Fog during DRAGON Campaigns from AERONET Ground-Based Remote Sensing  

NASA Astrophysics Data System (ADS)

Ground-based remote sensing observations from AERONET sun-sky radiometers have recently shown several instances where cloud-aerosol interaction had resulted in modification of aerosol properties. AERONET has established Distributed Regional Aerosol Gridded Observation Networks (DRAGON) during field campaigns that are short-term (~2-3 months) relatively dense spatial networks of ~15 to 45 sun and sky scanning photometers. Recent major DRAGON field campaigns in South Korea (Spring 2012) and California (Winter 2013) have yielded observations of aerosol property modification as a result of fog interaction. Extensive fog that was coincident with aerosol layer height on some days resulted in large increases in fine mode aerosol radius, with a mode of cloud-processed or residual aerosol of radius ~0.4-0.5 micron sometimes observed. Cloud processed aerosol may occur much more frequently than AERONET data suggest due to inherent difficulty in observing aerosol properties near clouds from remote sensing observations. Analysis of data from the Korean DRAGON campaign also shows that major pollution aerosol transport events are sometimes associated with extensive cloud cover and that cloud-screening of observations may at times filter out significant fine mode aerosol transport events. The Spectral De-convolution Algorithm (SDA) algorithm is utilized to isolate and analyze the fine mode aerosol signal for these cases of persistent and extensive cloud cover.

Eck, T. F.; Holben, B. N.; Schafer, J.; Giles, D. M.; Kim, J.; Kim, Y. J.; Reid, J. S.; Pickering, K. E.; Crawford, J. H.; Sinyuk, A.; Trevino, N.

2013-12-01

145

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

146

Practising cloud-based telemedicine in developing countries.  

PubMed

In industrialised countries, telemedicine has proven to be a valuable tool for enabling access to knowledge and allowing information exchange, and showing that it is possible to provide good quality of healthcare to isolated communities. However, there are many barriers to the widespread implementation of telemedicine in rural areas of developing countries. These include deficient internet connectivity and sophisticated peripheral medical devices. Furthermore, developing countries have very high patients-per-doctor ratios. In this paper, we report our work on developing a cloud-based health information system, which promotes telemedicine and patient-centred healthcare by exploiting modern information and communication technologies such as OWL-ontologies and SQL-triggers. The reason for using cloud technology is twofold. First, cloud service models are easily adaptable for sharing patients health information, which is of prime importance in patient-centred healthcare as well as in telemedicine. Second, the cloud and the consulting physicians may locate anywhere in the internet. PMID:24191340

Puustjärvi, Juha; Puustjärvi, Leena

2013-01-01

147

A Cloud-Based Simulation Architecture for Pandemic Influenza Simulation  

PubMed Central

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

148

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

149

Climatology Of Thin Cirrus Clouds at Gadanki (13.5°N, 79.2°E) Using Ground Based Lidar And Satellite Based Measurements  

NASA Astrophysics Data System (ADS)

High altitude cirrus clouds play a significant role in the radiative balance of Earth atmosphere system. Information on cirrus occurrences and their optical properties is essential for climate modeling studies. The influence of high altitude thin cirrus clouds on the climate is important due to their optical and thermodynamic properties. In order to quantify their effect on atmosphere, the vertical structure and optical properties of these thin cirrus clouds are to be characterized. The Lidar technique has become a unique tool for detecting and characterizing cirrus clouds for their optical properties. Ground based LIDAR system offers an excellent way to obtain characteristic values on the cirrus formations, although the microphysical and optical properties of thin cirrus clouds can also obtained on global scale by the observations from Earth-orbiting Satellites .The ground-based lidar observations could provide more intensive measurements on continuous basis, compared to satellite observations. Utilising observations from both, the statistical characteristics, physical and optical properties of thin cirrus clouds can be retrieved more precisely. The present study is based on the ground based lidar measurements using the pulsed monostatic LIDAR system at the National Atmospheric Research Laboratory [NARL], Gadanki (13.5° N, 79.2° E), Andhra Pradesh, India. The data obtained in the altitude range of 8-20 km are used for this study. Cirrus observations made using CALIPSO and MODIS satellites are compared with the ground based lidar data for systematic statistical study of cirrus climatology. Optically thin cirrus clouds (? < 0.3) observed during 2009 are selected and their microphysical and geometrical properties are studied. The microphysical properties such as optical depth, lidar ratio and depolarisation ratio for cirrus clouds were obtained. It is observed that the variability in optical depth depends on the composition and thickness of the clouds. The relationships between various quantities were also processed. The study shows that the thin cirrus generally was present in higher altitudes and the optical properties show correlation with the height and the temperature.

Motty, G. S.; Jayeshlal, G. S.; Satyanarayana, M.

2014-11-01

150

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

151

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

152

Identity-based Encryption with Outsourced Revocation in Cloud Computing  

E-print Network

1 Identity-based Encryption with Outsourced Revocation in Cloud Computing Jin Li, Jingwei Li, Xiaofeng Chen, Chunfu Jia and Wenjing Lou, Senior Member, IEEE Abstract--Identity-Based Encryption (IBE the burden that IBE strives to alleviate. In this paper, aiming at tackling the critical issue of identity

Hou, Y. Thomas

153

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

154

Ground Based Monitoring of Cloud Activity on Titan  

NASA Astrophysics Data System (ADS)

We will report on the latest results of an on-going ground based monitoring campaign of Saturn’s moon Titan using the SINFONI (Spectrograph for INtegral Field Observations in the Near Infrared) instrument on the Very Large Telescope (VLT). Presently, much is still unknown about the complex and dynamic hydrologic system of Titan as observations have yet to be made through an entire Titan year (29.7 Earth years). Because of the limited ability to observe Titan with Cassini, a combined ground and spaced-based approach provides a steady cadence of observation throughout the duration of a Titan year. We will present the results of observations to date using the adaptive optics (AO) mode (weather dependent) of SINFONI. We have been regularly observing Titan since April 2014 for the purpose of monitoring and identifying clouds and have also been in collaboration with the Cassini team that has concurrent ISS observations and historical VIMS observations of clouds. Our discussion will focus on the various algorithms and approaches used for cloud identification and analysis. Currently, we are entering into a very interesting time for clouds and Titan hydrology as Saturn moves into north polar summer for the first time since Cassini entered the Saturnian system. The increased insolation that this will bring to the north, where the majority of the liquid methane lakes reside, will give us our first observations of the potentially complex interplay between surface liquid and atmospheric conditions. By carefully monitoring and characterizing clouds (size, optical depth, altitude, etc.) we will also be able to derive constraints that can help to guide and validate GCMs. Since the beginning of our observations, no clouds have been observed through ground based observations, while Cassini has only observed a single cloud event in the north polar region over Ligeia Mare. We will provide an update on the latest results of our cloud monitoring campaign and discuss how this atmospheric inactivity and the frequency and characteristics of future cloud outbursts enhances our current understanding of Titan's hydrologic system.

Corlies, Paul; Hayes, Alexander; Rojo, Patricio; Ádámkovics, Máté; Turtle, Elizabeth; Buratti, Bonnie

2014-11-01

155

Retrieval algorithms for cloud motion from ground-based images  

NASA Astrophysics Data System (ADS)

We present the preliminary results of a project, focused on obtaining information about the velocity and direction of motion of air masses by means of ground-based measurements of visible cloud motion. This information can be used in short-term local weather forecast and is helpful in studies of the dynamics of the physical processes in clouds. We report the recent progress in the development of algorithms and tools for retrieving the three-dimensional field of vectors of velocity of cloud motion from time series of ground-based digital images. The visible motion of a cloud is the compound effect of the translational drift of the cloud as a whole with the velocity of the adjacent air masses, and of deformations due to the physical processes in the atmosphere. Because of the continuous changes of shape, extracting the translational component in the displacement of a cloud from a series of consecutive images is a highly non-trivial problem. Our approach consists in selecting a set of characteristic reference patterns of the cloud on the first image of the series, tracking them on the subsequent images, and evaluating this way the individual displacement of each reference pattern. Specific algorithms are being developed for the optimal choice of the reference patterns on the starting image and the recognition of these patterns on the subsequent images, depending on the type of the observed cloud. For clouds with low contrast or no edges, such as Stratus, Nimbostratus and Stratocumulus, implementations of the Optical Flow method are under development. For clouds with distinct contours, such as Cumulus and Altocumulus, the edges are decomposed into one-dimensional curvilinear patterns. To reduce the uncertainties, a multi-parametric model of the transformations of the cloud shape between images is defined next which, besides parallel transport, also involves dilatation, rotation, and possibly some local deformations. The parameters of the model are calculated from the individual displacements of the patterns by a least-square fit. What is obtained this way is a smooth approximation to the two-dimensional field of angular velocities of the cloud surface as seen from the observer's position. The three-dimensional vectors of velocity of the cloud are calculated by combining the results of multiple synchronous observations from distant sites. Prior to be put together, the data from different observers are corrected for optical distortion. We analyse the various sources of uncertainty of the calculated velocities of air masses, related to inaccuracy of the digital images, to identification errors in tracking the reference patterns on the series of images and to triangulation. We show that external telemetric information about the distance to the observed clouds may reduce the uncertainty of the results. We also discuss the optimal choice of the time interval between consecutive images as a compromise between the increasing requirements for computational power and the higher efficiency of the pattern recognition methods at shorter time intervals. The work is partially supported by the Bulgarian NFSR under contract NZ-1414/04.

Bakalova, Kalinka

156

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

157

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

E-print Network

. The proposed cloud-based re-encryption model is secure, efficient, and highly scalable in a cloud computing the performance of the model. Keywords-Distributed systems, mobile computing, security. I. INTRODUCTION Cloud rated security as the chief concern in the use of cloud computing services [1]; the concern

158

Data Security in Cloud Architecture Based on Diffie Hellman and Elliptical Curve Cryptography  

E-print Network

Data Security in Cloud Architecture Based on Diffie Hellman and Elliptical Curve Cryptography Neha towards cloud architecture. Cloud computing is technology where the users' can use high end services new security threats towards the certitude of data in cloud. The security threats such as maintenance

159

Learning-based computing techniques in geoid modeling for precise height transformation  

NASA Astrophysics Data System (ADS)

Precise determination of local geoid is of particular importance for establishing height control in geodetic GNSS applications, since the classical leveling technique is too laborious. A geoid model can be accurately obtained employing properly distributed benchmarks having GNSS and leveling observations using an appropriate computing algorithm. Besides the classical multivariable polynomial regression equations (MPRE), this study attempts an evaluation of learning based computing algorithms: artificial neural networks (ANNs), adaptive network-based fuzzy inference system (ANFIS) and especially the wavelet neural networks (WNNs) approach in geoid surface approximation. These algorithms were developed parallel to advances in computer technologies and recently have been used for solving complex nonlinear problems of many applications. However, they are rather new in dealing with precise modeling problem of the Earth gravity field. In the scope of the study, these methods were applied to Istanbul GPS Triangulation Network data. The performances of the methods were assessed considering the validation results of the geoid models at the observation points. In conclusion the ANFIS and WNN revealed higher prediction accuracies compared to ANN and MPRE methods. Beside the prediction capabilities, these methods were also compared and discussed from the practical point of view in conclusions.

Erol, B.; Erol, S.

2013-03-01

160

Classification of Cloud Types Through Infrared APT Imagery  

NSDL National Science Digital Library

This activity is designed to teach students about the different classes of clouds, as well as how they are classified. Students will learn about classification by performing their own classification of clouds based on information given them by instructors. Students will also use infrared ATP images to study clouds by height, temperature, and appearance.

P Costulis

2002-09-30

161

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

162

The Impact of SST-anomaly Gradients on Cloud Base and Precipitation - Implications for Long Range Forecasts  

NASA Astrophysics Data System (ADS)

Precipitation intensity at the ground depends strongly on cloud base height and the relative humidity of the sub-cloud layer, primarily because these factors affect particle evaporation. As airmasses move from the ocean towards Western Europe (and other geographically similar parts of the world) they cross sea surface temperature (SST) gradients, and heat and moisture fluxes to/from the ocean change. A simple hypothesis will be presented for NW Europe to illustrate how different signs of the along-trajectory SST-anomaly gradient will influence the relative moistening or drying of the lower troposphere, and hence cloud base height. In turn this can affect the intensity and amounts of precipitation falling from fronts and cyclonic systems as they move across this region. Numerical model evidence for this effect will be presented using operational ECMWF ensemble output for the exceptionally wet summer of 2007 over the UK. Once SSTs around the UK had undergone a marked reduction, at the end of June, due to passage of a major cyclonic storm, the longer range forecasts became systematically wetter. Soil moisture anomalies are likely to have been an additional contributory factor, notably when the low level airmass trajectory was from the near continent. One tentative, positive conclusion from the above is that there may be scope for cheap, statistical forecasts of precipitation anomalies to have some skill for as long as current SST anomaly patterns persist. Meanwhile one downside is that numerical model predictions of the same are liable to fail if they do not capture a major cyclonic storm, at long range, which disrupts the SST pattern. They would also need to correctly represent the impact on SSTs, and thereby on SST-anomaly gradients, of such a storm. These are major challenges. Possible feedbacks between cloud base height, storm structure and cyclonic activity will also be briefly mentioned.

Hewson, T. D.

2009-04-01

163

A secure medical data exchange protocol based on cloud environment.  

PubMed

In recent years, health care technologies already became matured such as electronic medical records that can be easily stored. However, how to get medical resources more convenient is currently concern issue. In spite of many literatures discussed about medical systems, but these literatures should face many security challenges. The most important issue is patients' privacy. Therefore, we propose a secure medical data exchange protocol based on cloud environment. In our scheme, we use mobile device's characteristics, allowing peoples use medical resources on the cloud environment to seek medical advice conveniently. PMID:25037716

Chen, Chin-Ling; Yang, Tsai-Tung; Shih, Tzay-Farn

2014-09-01

164

Filtering of LIDAR Point Cloud Using a Strip Based Algorithm in Residential Mountainous Areas  

NASA Astrophysics Data System (ADS)

Several algorithms have been developed to automatically detect the bare earth in LIDAR point clouds referred to as filtering. Previous experimental study on filtering algorithms determined that in flat and uncomplicated landscapes, algorithms tend to do well. Significant differences in accuracies of filtering appear in landscapes containing steep slopes and discontinuities. A solution for this problem is the segmentation of ALS point clouds. In this paper a new segmentation has been developed. The algorithm starts with first slicing a point cloud into contiguous and parallel profiles in different directions. Then the points in each profile are segmented into polylines based on distance and elevation proximity. The segmentation in each profile yields polylines. The polylines are then linked together through their common points to obtain surface segments. At the final stage, the data is partitioned into some windows in which the strips are exploited to analysis the points with regard to the height differences through them. In this case the whole data could be fully segmented into ground and non-ground measurements, sequentially via the strips which make the algorithm fast to implement.

Hosseini, S. A.; Arefi, H.; Gharib, Z.

2014-10-01

165

Atmospheric Cloud Forecasting in Support of Space Based Applications  

NASA Astrophysics Data System (ADS)

Many space based applications from imaging to communications are impacted by the atmosphere. Atmospheric impacts such as optical turbulence and clouds are the main drivers for these types of systems. For example, in space based optical communications, clouds will produce channel fades on the order of many hundreds of decibels (dB) thereby breaking the communication link. Optical turbulence can also produce fades but can be compensated for by adaptive optics. The ability to forecast the current and future location and optical thickness of clouds for spaced based to ground optical communications is therefore critical in order to achieve a highly reliable system. We have developed an innovative method for producing such forecasts. These forecasts are intended to provide lead times on the order of several hours so that communication links can be transferred from a current clear ground location to another more desirable ground site. The system is referred to as the Cloud Propagator Forecast (CPF) and it operates on successive, satellite remotely sensed, cloud analyses to produce reliable probability forecasts of future cloud cover conditions at each point location or for the expectation of the amount of skycover in a local skydome about each point location. The forecasting algorithm is a combination of empirical Lagrangian and Eulerian regression over multiple spatial scales, but treats time auto-regressively. Input cloud masks are transformed into proxies first. A cloud cover proxy is a variable which has a more Gaussian distribution than literal cloud cover. For a given pixel, the cloud cover proxy is computed first by determining whether at the initialization time the pixel was clear or cloudy. Clear pixels will be assigned only positive proxies; cloudy pixels will be given only negative proxies. The degree the assigned proxy is different than zero depends on the fraction of pixels in a small neighboring space which have similar cloudy/clearness. The neighboring space is approximately the spatial scale of a skydome and has a temporal scale of one hour. Pixels which are unlike their neighbors will have proxies close to zero, those largely identical to their neighbors will has proxies close to plus or minus one. Final cloud proxies are computed using a non-linear transform to stretch out the extremes into a pseudo-Gaussian distribution. The model then decomposes the proxy fields into scale-filtered components. Longer spatial scale patterns are expected to be more predictable over time; shorted scales less so. Differentiating them allows the model to retain the maximum predictive skill through training. The resulting forecasts have several desirable characteristics. First, they evidence substantial skill when compared to persistence. Additionally, these forecasts extrapolate movement of cloud features, and also allow for degradation of fine scale features without compromising more predictable larger scales. The forecasts are reliable, in that specific probability categories will assess at their stated probabilities, and also consequently unbiased. Details of the algorithm and results used for a realtime spaced based application will be shown at the conference.

Alliss, R. J.; Felton, B.; Apling, D.

2013-09-01

166

A Cloud-based Approach to Medical NLP  

PubMed Central

Natural Language Processing (NLP) enables access to deep content embedded in medical texts. To date, NLP has not fulfilled its promise of enabling robust clinical encoding, clinical use, quality improvement, and research. We submit that this is in part due to poor accessibility, scalability, and flexibility of NLP systems. We describe here an approach and system which leverages cloud-based approaches such as virtual machines and Representational State Transfer (REST) to extract, process, synthesize, mine, compare/contrast, explore, and manage medical text data in a flexibly secure and scalable architecture. Available architectures in which our Smntx (pronounced as semantics) system can be deployed include: virtual machines in a HIPAA-protected hospital environment, brought up to run analysis over bulk data and destroyed in a local cloud; a commercial cloud for a large complex multi-institutional trial; and within other architectures such as caGrid, i2b2, or NHIN. PMID:22195072

Chard, Kyle; Russell, Michael; Lussier, Yves A.; Mendonça, Eneida A; Silverstein, Jonathan C.

2011-01-01

167

Ontology-Based Emergency Management System in a Social Cloud  

E-print Network

The need for Emergency Management continually grows as the population and exposure to catastrophic failures increase. The ability to offer appropriate services at these emergency situations can be tackled through group communication mechanisms. The entities involved in the group communication include people, organizations, events, locations and essential services. Cloud computing is a "as a service" style of computing that enables on-demand network access to a shared pool of resources. So this work focuses on proposing a social cloud constituting group communication entities using an open source platform, Eucalyptus. The services are exposed as semantic web services, since the availability of machine-readable metadata (Ontology) will enable the access of these services more intelligently. The objective of this paper is to propose an Ontology-based Emergency Management System in a social cloud and demonstrate the same using emergency healthcare domain.

A, Bhuvaneswari

2011-01-01

168

16-year Climatology of Cirrus cloud properties using ground-based Lidar over Gadanki (13.45?N, 79.18?E)  

NASA Astrophysics Data System (ADS)

Cirrus clouds are ubiquitous high level cold clouds predominantly consisting of ice-crystals. With their highest coverage over the tropics, these are one of the most vital and complex components of Tropical Tropopause Layer (TTL) due to their strong radiative feedback and dehydration in upper troposphere and lower stratosphere (UTLS) regions. The continuous changes in their coverage, position, thickness, and ice-crystal size and shape distributions bring uncertainties in the estimates of cirrus cloud radiative forcing. Long-term changes in the distribution of aerosols and water vapour in the TTL can influence cirrus properties. This necessitates long-term studies of tropical cirrus clouds, which are only few. The present study provides 16-year climatology of physical and optical properties of cirrus clouds observed using a ground-based Lidar located at Gadanki (13.45(°) N, 79.18(°) ?E and 375 m amsl) in south-India. In general, cirrus clouds occurred for about 44% of the total Lidar observation time. Owing to the increased convective activities, the occurrence of cirrus clouds during the southwest-monsoon season is highest while it is lowest during the winter. Altitude distribution of cirrus clouds reveals that the peak occurrence was about 25% at 14.5 km. The most probable base and top height of cirrus clouds are 14 and 15.5 km, respectively. This is also reflected in the bulk extinction coefficient profile (at 532 nm) of cirrus clouds. These results are compared with the CALIPSO observations. Most of the time cirrus clouds are located within the TTL bounded by convective outflow level and cold-point tropopause. Cirrus clouds are thick during the monsoon season as compared to that during winter. An inverse relation between the thickness of cirrus clouds and TTL thickness is found. The occurrence of cirrus clouds at an altitude close to the tropopause (16 km) showed an increase of 8.4% in the last 16 years. Base and top heights of cirrus clouds also showed increase of 0.41 km and 0.56 km, respectively. These results are discussed in relation with the recent increase in the tropical tropopause altitude.

Pandit, Amit Kumar; Raghunath, Karnam; Jayaraman, Achuthan; Venkat Ratnam, Madineni; Gadhavi, Harish

169

Cloud Protocols  

NSDL National Science Digital Library

The purpose of this activity is to observe the type and cover of clouds including contrails. Students observe which of ten types of clouds and how many of three types of contrails are visible and how much of the sky is covered by clouds (other than contrails) and how much is covered by contrails. Intended outcomes are that students learn how to make estimates from observations and how to categorize specific clouds following general descriptions for the categories. They will learn the meteorological concepts of cloud heights, types, and cloud cover and learn the ten basic cloud types. Supporting background materials for both student and teacher are included.

The GLOBE Program, UCAR (University Corporation for Atmospheric Research)

2003-08-01

170

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

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

Measuring heights to crown base and crown median with LiDAR in a mature, even-aged loblolly pine stand  

Microsoft Academic Search

This study evaluated the possibility of measuring the height to the base of the live crown and the height to the median of canopy elements with airborne scanning LiDAR (Light Detection And Ranging) in a simple, even-aged stand of loblolly pine. The first step in determining these heights was fitting truncated Weibull functions to the vertical distribution of elevations where

Thomas J. Dean; Quang V. Cao; Scott D. Roberts; David L. Evans

2009-01-01

173

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

174

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

175

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

176

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

177

Joint retrievals of cloud and drizzle in marine boundary layer clouds using ground-based radar, lidar and zenith radiances  

NASA Astrophysics Data System (ADS)

Active remote sensing of marine boundary-layer clouds is challenging as drizzle drops often dominate the observed radar reflectivity. We present a new method to simultaneously retrieve cloud and drizzle vertical profiles in drizzling boundary-layer cloud using surface-based observations of radar reflectivity, lidar attenuated backscatter, and zenith radiances. Specifically, the vertical structure of droplet size and water content of both cloud and drizzle is characterised throughout the cloud. An ensemble optimal estimation approach provides full error statistics given the uncertainty in the observations. To evaluate the new method, we first perform retrievals using synthetic measurements from large-eddy simulation snapshots of cumulus under stratocumulus, where cloud water path is retrieved with an error of 31 g m-2. The method also performs well in non-drizzling clouds where no assumption of the cloud profile is required. We then apply the method to observations of marine stratocumulus obtained during the Atmospheric Radiation Measurement MAGIC deployment in the northeast Pacific. Here, retrieved cloud water path agrees well with independent 3-channel microwave radiometer retrievals, with a root mean square difference of 10-20 g m-2.

Fielding, M. D.; Chiu, J. C.; Hogan, R. J.; Feingold, G.; Eloranta, E.; O'Connor, E. J.; Cadeddu, M. P.

2015-02-01

178

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

179

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

180

Property-Based Remote Attestation Oriented to Cloud Computing  

Microsoft Academic Search

As the new computing service pattern of cloud computing develops rapidly, the security problem of cloud computing has become a hot research topic. Before the user passes important data or computing task to the cloud, the user of the cloud may want to verify the trusted status of the platform which actually carries out the computing task in the cloud.

SiYuan Xin; Yong Zhao; Yu Li

2011-01-01

181

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

182

Observations of the Interaction and/or Transport of Aerosols with Cloud or Fog during DRAGON Campaigns from AERONET Ground-Based Remote Sensing  

NASA Astrophysics Data System (ADS)

Ground-based remote sensing observations from Aerosol Robotic Network (AERONET) sun-sky radiometers have recently shown several instances where cloud-aerosol interaction had resulted in modification of aerosol properties and/or in difficulty identifying some major pollution transport events due to aerosols being imbedded in cloud systems. AERONET has established Distributed Regional Aerosol Gridded Observation Networks (DRAGON) during field campaigns that are short-term (~2-3 months) relatively dense spatial networks of ~15 to 45 sun and sky scanning photometers. Recent major DRAGON field campaigns in Japan and South Korea (Spring 2012) and California (Winter 2013) have yielded observations of aerosol transport associated with clouds and/or aerosol properties modification as a result of fog interaction. Analysis of data from the Korean and Japan DRAGON campaigns shows that major fine-mode aerosol transport events are sometimes associated with extensive cloud cover and that cloud-screening of observations often filter out significant pollution aerosol transport events. The Spectral De-convolution Algorithm (SDA) algorithm was utilized to isolate and analyze the fine-mode aerosol optical depth signal for these cases of persistent and extensive cloud cover. Additionally, extensive fog that was coincident with aerosol layer height on some days in both Korea and California resulted in large increases in fine mode aerosol radius, with a mode of cloud-processed or residual aerosol of radius ~0.4-0.5 micron sometimes observed. Cloud processed aerosol may occur much more frequently than AERONET data suggest due to inherent difficulty in observing aerosol properties near clouds from remote sensing observations. These biases of aerosols associated with clouds would likely be even greater for satellite remote sensing retrievals of aerosol properties near clouds due to 3-D effects and sub-pixel cloud contamination issues.

Eck, Thomas; Holben, Brent; Schafer, Joel; Giles, David; Kim, Jhoon; Kim, Young; Sano, Itaru; Reid, Jeffrey; Pickering, Kenneth; Crawford, James; Sinyuk, Alexander; Trevino, Nathan

2014-05-01

183

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

184

Efficient Resources Provisioning Based on Load Forecasting in Cloud  

PubMed Central

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

185

Role and Attribute Based Collaborative Administration of Intra-Tenant Cloud IaaS  

E-print Network

Role and Attribute Based Collaborative Administration of Intra-Tenant Cloud IaaS (Invited Paper--Cloud Infrastructure as a Service (IaaS), where traditional IT infrastructure resources such as compute, storage requirements. In this paper, we investigate attribute-based access control (ABAC) in cloud IaaS. In ABAC

Sandhu, Ravi

186

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

E-print Network

A 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 is then introduced. Combined with empirical threshold values, we determine if the signal waves indicate clouds

Li, Zhanqing

187

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)

188

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

189

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

190

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

191

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

192

SmartFarm Private and Local Cloud-based Sensor System for  

E-print Network

SmartFarm Private and Local Cloud-based Sensor System for Simplifying are limited (arable land, water, ...) ­ Hard to predict weather paTerns, climate change-premise (private) cloud · Easy to use, self managing ­ Linking disparate sensor technologies

Bigelow, Stephen

193

[Analysis of cloud spectral structure characteristics based on cloud profile radar data].  

PubMed

Cloud plays a very important role in the earth-atmosphere system. However, the current climate models are still lacking data about internal fine structure of cloud. And when the traditional passive satellite radiometer is used for remote sense, a plentiful information of the vertical distribution of cloud layer will be lost. For these reasons, NASA proposed the launch project of CloudSat, Whose purpose is to provide the necessary observation, and then allow us to understand better the internal structure of the cloud. CloudSat was successfully launched on April 28, 2006. It carried the first cloud profile radar (CPR) with W band (94 GHz), which can provide continuous and global time sequence vertical structure and characteristics of cloud. In the present paper, using CloudSat satellite data, we analyzed the 8th "Morakot" and 15th " Koppu" typhoon cloud systems. According to the "typhoon" cloud detection results, the radar reflectivity, cloud types and optical thickness successive variation of cloud layer were gotten, which will provide a reference for studying optical properties of typhoon cloud system. PMID:23841397

Han, Yong; Lü, Da-Ren

2013-04-01

194

A Coalitional Game-Based Mechanism for Forming Cloud Federations  

E-print Network

In this paper, we consider the IaaS offering by a federation of cloud providers. A cloud federation providers offer IaaS using virtualization of low level resources. Cloud providers provision their resources

Grosu, Daniel

195

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

Microsoft Academic Search

.  ?A wide-angle airborne laser ranging system has been developed for the determination of relative heights of ground-based benchmarks\\u000a 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\\u000a first aircraft experiment was conducted in 1998, over a small area (1

O. Bock; C. Thom

2002-01-01

196

How Accurate is Web-Based Self-Reported Height, Weight, and Body Mass Index in Young Adults?  

PubMed Central

Background Web-based approaches are an effective and convenient medium to deliver eHealth interventions. However, few studies have attempted to evaluate the accuracy of online self-reported weight, and only one has assessed the accuracy of online self-reported height and body mass index (BMI). Objective This study aimed to validate online self-reported height, weight, and calculated BMI against objectively measured data in young Australian adults. Methods Participants aged 18-35 years were recruited via advertisements on social media sites and reported their current height and weight as part of an online survey. They then subsequently had the same measures objectively assessed by a trained researcher. Results Self-reported height was significantly overestimated by a mean of 1.36 cm (SD 1.93; P<.001), while self-reported weight was significantly underestimated by –0.55 kg (SD 2.03; P<.001). Calculated BMI was also underestimated by –0.56 kg/m2 (SD 0.08; P<.001). The discrepancy in reporting resulted in the misclassification of the BMI category of three participants. Measured and self-reported data were strongly positively correlated (height: r=.98, weight: r=.99, BMI: r=.99; P<.001). When accuracy was evaluated by BMI category and gender, weight remained significantly underreported by females (P=.002) and overweight/obese participants (P=.02). Conclusions There was moderate to high agreement between self-reported and measured anthropometric data. Findings suggest that online self-reported height and weight can be a valid method of collecting anthropometric data. PMID:24398335

2014-01-01

197

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

198

A privacy authentication scheme based on cloud for medical environment.  

PubMed

With the rapid development of the information technology, the health care technologies already became matured. Such as electronic medical records that can be easily stored. However, how to get medical resources more convenient is currently concerning issue. In spite of many literatures discussed about medical systems, these literatures should face many security challenges. The most important issue is patients' privacy. Therefore, we propose a privacy authentication scheme based on cloud environment. In our scheme, we use mobile device's characteristics, allowing peoples to use medical resources on the cloud environment to find medical advice conveniently. The digital signature is used to ensure the security of the medical information that is certified by the medical department in our proposed scheme. PMID:25315823

Chen, Chin-Ling; Yang, Tsai-Tung; Chiang, Mao-Lun; Shih, Tzay-Farn

2014-11-01

199

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

200

Comparison of CERES-MODIS and CloudSat/CALIPSO cloud properties with DOE ARM AMF measurements at Shouxian, China  

NASA Astrophysics Data System (ADS)

Cloud properties derived from both the CERES-MODIS SSF Ed-2B products and CloudSat/CALIPSO level 2B products have been compared with Department of Energy, Atmospheric Radiation Measurements Mobile Facility (DOE AMF) measurements taken at the Shouxian site (32.55N, 116.78E), China during the period Oct. 15-Dec. 15 of 2008. The AMF data, such as cloud base/top heights and liquid water path are averaged over a 1-h interval centered at the time of each satellite overpass, and the CERES-MODIS and CloudSat/CALIPSO cloud properties are averaged within a 1x1 degree grid box centered at the Shouxian site. A total of 41 satellite overpasses have been selected for this study. The preliminary results show that most of the cloud effective heights derived from CERES-MODIS agree very well with the ARM cloud radar-lidar observations. However, some discrepancies in cloud LWP exist between MODIS and ARM AMF observations. For CERES-MODIS data, the median and mean of cloud effective heights are 6.6 and 6.9 km, respectively. The median and mean of cloud-base height observed by AMF cloud radar are 4.4 and 4.1 km, they are 8.5 and 7.9 km for cloud-top height. During the ARM AMF deployment, four cloud systems have been observed by both surface and satellite and used to improve our understanding to the cloud formation, growth, and dissipation process. For the observed four cloud systems, we will investigate the effect of CCN loading on the different stage of cloud process, and/or show how the satellite observations can improve our knowledge of the evolving process of clouds. The vertical profiles of cloud properties observed by both CloudSat/CALIPSO and ARM cloud radar are also compared where the peak reflectivity heights measured by CloudSat/CALIPSO are ~ 0.5 km lower than that measured by the ARM radar/lidar for both high level clouds and low level clouds.

Qiu, Y.; Dong, X.; Xi, B.; Minnis, P.

2010-12-01

201

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

202

Satellite-based estimate of global aerosol-cloud radiative forcing by marine warm clouds  

NASA Astrophysics Data System (ADS)

Changes in aerosol concentrations affect cloud albedo and Earth's radiative balance. Aerosol radiative forcing from pre-industrial time to the present due to the effect of atmospheric aerosol levels on the micro- and macrophysics of clouds bears the largest uncertainty among external influences on climate change. Of all cloud forms, low-level marine clouds exert the largest impact on the planet's albedo. For example, a 6% increase in the albedo of global marine stratiform clouds could offset the warming that would result from a doubling of atmospheric CO2 concentrations. Marine warm cloud properties are thought to depend on aerosol levels and large-scale dynamic or thermodynamic states. Here we present a comprehensive analysis of multiple measurements from the A-Train constellation of Earth-observing satellites, to quantify the radiative forcing exerted by aerosols interacting with marine clouds. Specifically, we analyse observations of co-located aerosols and clouds over the world's oceans for the period August 2006-April 2011, comprising over 7.3 million CloudSat single-layer marine warm cloud pixels. We find that thermodynamic conditions--that is, tropospheric stability and humidity in the free troposphere--and the state of precipitation act together to govern the cloud liquid water responses to the presence of aerosols and the strength of aerosol-cloud radiative forcing.

Chen, Yi-Chun; Christensen, Matthew W.; Stephens, Graeme L.; Seinfeld, John H.

2014-09-01

203

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

204

Modeling Performance of Elasticity Rules for Cloud-based Applications  

E-print Network

Science and Engineering The University of New South Wales Sydney 2052, Australia #12;Abstract Many IaaS, on such IaaS clouds so their applications can inherently become self-elastic to meet its variable workload, on an Infrastructure as a Service (IaaS) cloud such as Amazon's Elastic Cloud Compute (EC2) and GoGrid's Cloud Hosting

New South Wales, University of

205

Strengthen Cloud Computing Security with Federal Identity Management Using Hierarchical Identity-Based Cryptography  

NASA Astrophysics Data System (ADS)

More and more companies begin to provide different kinds of cloud computing services for Internet users at the same time these services also bring some security problems. Currently the majority of cloud computing systems provide digital identity for users to access their services, this will bring some inconvenience for a hybrid cloud that includes multiple private clouds and/or public clouds. Today most cloud computing system use asymmetric and traditional public key cryptography to provide data security and mutual authentication. Identity-based cryptography has some attraction characteristics that seem to fit well the requirements of cloud computing. In this paper, by adopting federated identity management together with hierarchical identity-based cryptography (HIBC), not only the key distribution but also the mutual authentication can be simplified in the cloud.

Yan, Liang; Rong, Chunming; Zhao, Gansen

206

Cloud Thickness from Offbeam Returns - Thor Lidar  

NASA Technical Reports Server (NTRS)

Physical thickness of a cloud layer, and sometimes multiple cloud layers, can be estimated from the time delay of off-beam returns from a pulsed laser source illuminating one side of the cloud layer. In particular, the time delay of light returning from the outer diffuse halo of light surrounding the beam entry point, relative to the time delay at beam center, determines the cloud physical thickness. The delay combined with the pulse stretch gives the optical thickness. The halo method works best for thick cloud layers, typically optical thickness exceeding 2, and thus compliments conventional lidar which cannot penetrate thick clouds. Cloud layer top and base have been measured independently over the ARM/SGP site using conventional laser ranging (lidar) and the top minus base thickness are compared with a cloud top halo estimate obtained from the NASA/Goddard THOR System (THOR = THickness from Offbeam Returns). THOR flies on the NASA P3, and measures the halo timings from several km above cloud top, at the same time providing conventional lidar cloud top height. The ARM/SGP micropulse lidar provides cloud base height for validation.

Cahalan, R.; Kolasinski, J.; McGill, M.; Lau, William K. M. (Technical Monitor)

2002-01-01

207

A Petri Net Model for Secure and Fault-Tolerant Cloud-Based Information Storage  

E-print Network

in a compromise of the overall data set. Keywords-Cloud computing; information storage; data security; fault done in regards to data security, ownership and privacy in cloud computing. A survey conducted333 A Petri Net Model for Secure and Fault-Tolerant Cloud-Based Information Storage Daniel F. Fitch

Xu, Haiping

208

Adopting Provenance-Based Access Control in OpenStack Cloud IaaS  

E-print Network

Adopting Provenance-Based Access Control in OpenStack Cloud IaaS Dang Nguyen, Jaehong Park capabilities to the authorization engine of a multi-tenant cloud Infrastructure-as-a-Service (IaaS. PBAC can effectively be employed in a multi-tenant1 Infrastructure- as-a-Service (IaaS) cloud

Sandhu, Ravi

209

Scalable Reed-Solomon-based Reliable Local Storage for HPC Applications on IaaS Clouds  

E-print Network

Scalable Reed-Solomon-based Reliable Local Storage for HPC Applications on IaaS Clouds Leonardo users to run HPC appli- cations, Infrastructure-as-a-Service (IaaS) cloud computing platforms represent of thousands of cores. For these types of jobs, Infrastructure-as-a-Service (IaaS) [4] cloud platforms present

Boyer, Edmond

210

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

211

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

212

Evaluation Method of the Industry's Innovation Capacity Based on Cloud Model  

Microsoft Academic Search

With Innovative capital perspective, the proportion of R & D personnel, R & D intensity, R & D productivity and per capita number of patents are constructed as the industry's innovation capacity evaluation indexes. Using cloud theoretical framework, the evaluation method of industry's innovation capacity based on cloud model is built. Through the backward cloud algorithm, this method combines qualitative

Li Shan; Xu Shenghua

2010-01-01

213

Cumulus cloud transport of transient tracers  

NASA Technical Reports Server (NTRS)

A theoretical framework is developed for including cumulus cloud transport, rainout of water soluble gases, and aqueous phase chemistry into gas phase photochemical models. Cloud populations are represented as ensemble distributions of individual clouds of various heights. An individual cloud is represented as a one-dimensional, steady state plume with height-independent radius entraining air from the boundary of the cloud. The model is applied to several hypothetical atmospheric tracers to show how clouds may affect the tropospheric distributions of ozone, NO(y), SO2, peroxyacetylnitrate, hydrocarbons, and other gases. Although the numerical experiments were based on cloud mass fluxes from diagnostic studies in the tropics and thus are not representative of the entire globe, it was found that an increasing mixing ratio with height in the free troposphere can be produced for some gases with only a surface source when clouds are present. This suggests that some reactive tropospheric species with primarily surface sources may play a somewhat more important role in tropospheric chemistry than is presently believed depending on the global distribution of cloud mass fluxes. Deficiencies in existing photochemical models due to the way clouds are typically treated are discussed.

Gidel, L. T.

1983-01-01

214

Effects of Plant Density on Frequency Distributions of Plant Height in Chenopodium album Stands: Analysis Based on Continuous Monitoring of Height-growth of Individual Plants  

Microsoft Academic Search

Height-growth of individual plants of Chenopodium album in even-aged monospecific stands with initial densities of 400, 800, and 3600 plants m-2 was followed from emergence to fruit maturation to elucidate the factors responsible for size hierarchy formation. Many individuals stopped growing rather abruptly at relatively early stages in the vegetative phase and some of them eventually died. The other plants

Hisae Nagashima; Ichiro Terashima; Sakae Katoh

1995-01-01

215

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

216

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

217

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

218

Web-Based Self-Reported Height, Weight, and Body Mass Index Among Swedish Adolescents: A Validation Study  

PubMed Central

Background Web-collected height and weight are increasingly used in epidemiological studies; however, the validity has rarely been evaluated. Objective The aim of the study was to validate self-reported height, weight, and corresponding body mass index (BMI) among Swedish adolescents aged approximately 16 years. A secondary aim was to investigate possible prediction factors for validity of self-reported BMI. Methods The study included 1698 adolescents from the population-based cohort BAMSE. Height and weight were collected through a Web-based questionnaire and subsequently measured using standard procedures. Differences between reported and measured height, weight, and corresponding BMI were compared by t tests and agreement was evaluated by Pearson correlation and Bland-Altman plots. Multivariable linear regression analysis was used to investigate whether lifestyle and demographic factors predicted validity of self-reported BMI. Results On average, weight was underestimated by 1.1 kg and height was overestimated by 0.5 cm, leading to an underestimation of BMI by 0.5 kg/m2. Correlation coefficients were .98 for height, .97 for weight, and .94 for BMI, and highly significant. Females underestimated weight to a higher extent than males and overweight and obese participants underestimated weight to a higher extent than normal-weight participants, which resulted in higher underestimation of BMI. Underweight participants, on the contrary, overestimated weight and correspondingly BMI. Overall, a high proportion of participants were classified into the correct BMI category; however, among overweight and obese participants, only 60.2% (139/231) and 46% (20/44) were correctly classified, respectively. In the multivariable prediction model, only gender and BMI status significantly predicted discrepancy between reported and measured BMI. Conclusions Web-collected BMI may be used as a valid, quick, and cost-effective alternative to measured BMI among Swedish adolescents. The accuracy of self-reported BMI declines with increasing BMI and self-reported BMI should not be used to estimate the prevalence of overweight or obesity. PMID:25791395

Kull, Inger; Nilsson, Sara; Bergström, Anna

2015-01-01

219

On the Relationship between Thermodynamic Structure and Cloud Top, and Its Climate Significance in the Arctic  

E-print Network

capped by inversion (CCI)]. Cloud base and top heights were lower, and temperature inversions were also for CCI over Barrow. In-cloud lapse rates differ and suggest increased cloud-mixing potential for CII% of the CCI and more than 85% of the CII regimes. Horizontal advection of heat and moisture is hypothesized

Shupe, Matthew

220

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

221

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

222

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

223

A New Method of Cloud Detection Based on Cascaded AdaBoost  

NASA Astrophysics Data System (ADS)

Cloud detection of remote sensing image is a critical step in the processing of the remote sensing images. How to quickly, accurately and effectively detect cloud on remote sensing images, is still a challenging issue in this area. In order to avoid disadvantages of the current algorithms, the cascaded AdaBoost classifier algorithm is successfully applied to the cloud detection. A new algorithm combined cascaded AdaBoost classifier and multi-features, is proposed in this paper. First, multi-features based on the color, texture and spectral features are extracted from the remote sensing image. Second, the automatic cloud detection model is obtained based on the cascaded AdaBoost algorithm. In this paper, the results show that the new algorithm can determine cloud detection model and threshold values adaptively for different resolution remote sensing training data. The accuracy of cloud detection is improved. So it is a new effective algorithm for the cloud detection of remote sensing images.

Ma, C.; Chen, F.; Liu, J.; Duan, J.

2014-02-01

224

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

225

Min-Cut Based Segmentation of Airborne LIDAR Point Clouds  

NASA Astrophysics Data System (ADS)

Introducing an organization to the unstructured point cloud before extracting information from airborne lidar data is common in many applications. Aggregating the points with similar features into segments in 3-D which comply with the nature of actual objects is affected by the neighborhood, scale, features and noise among other aspects. In this study, we present a min-cut based method for segmenting the point cloud. We first assess the neighborhood of each point in 3-D by investigating the local geometric and statistical properties of the candidates. Neighborhood selection is essential since point features are calculated within their local neighborhood. Following neighborhood determination, we calculate point features and determine the clusters in the feature space. We adapt a graph representation from image processing which is especially used in pixel labeling problems and establish it for the unstructured 3-D point clouds. The edges of the graph that are connecting the points with each other and nodes representing feature clusters hold the smoothness costs in the spatial domain and data costs in the feature domain. Smoothness costs ensure spatial coherence, while data costs control the consistency with the representative feature clusters. This graph representation formalizes the segmentation task as an energy minimization problem. It allows the implementation of an approximate solution by min-cuts for a global minimum of this NP hard minimization problem in low order polynomial time. We test our method with airborne lidar point cloud acquired with maximum planned post spacing of 1.4 m and a vertical accuracy 10.5 cm as RMSE. We present the effects of neighborhood and feature determination in the segmentation results and assess the accuracy and efficiency of the implemented min-cut algorithm as well as its sensitivity to the parameters of the smoothness and data cost functions. We find that smoothness cost that only considers simple distance parameter does not strongly conform to the natural structure of the points. Including shape information within the energy function by assigning costs based on the local properties may help to achieve a better representation for segmentation.

Ural, S.; Shan, J.

2012-07-01

226

Predicting within-family variability in juvenile height growth of Salix based upon similarity among parental AFLP fingerprints.  

PubMed

Willow is being developed as a crop for biomass plantations in the Northeast and North-central United States, but has only recently been the subject of controlled breeding to generate improved genotypes. Maximizing variability among progeny within full-sib families produced by controlled pollination may increase the probability of producing willow clones exhibiting desirable extreme phenotypes. Yet, predicting combinations of parents yielding highly variable progeny is not currently possible. Controlled pollinations were completed among 15 Salix eriocephala clones and the resulting progeny were vegetatively propagated and planted in a greenhouse progeny test. Heights of rooted cuttings were measured after 4 months of growth. Genetic similarity among parents was estimated based on 77 polymorphic AFLP bands. Strong negative correlation ( r = -0.88) was detected between mean female-parent similarity indices and the standard deviation of height among half-sib progeny from those females. Parent combinations that had relatively low similarity indices tended to produce progeny that had greater variability in height. This negative relationship suggests that AFLP fingerprints of S. eriocephala parents may be useful for predicting parent combinations that will yield families with large variability. PMID:12582568

Kopp, F.; Smart, B.; Maynard, A.; Tuskan, A.; Abrahamson, P.

2002-07-01

227

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

228

Satellite-based 3D structure of cloud and aerosols over the Indian Monsoon region: implications for aerosol-cloud interaction  

NASA Astrophysics Data System (ADS)

Accurate knowledge of vertical distributions of aerosol and cloud fields and their space-time variations are required to reduce the uncertainty in estimated climate forcing. Here, multi-sensor (both passive and active) data were used to construct the climatology of 3-D cloud and aerosol fields over the Indian monsoon region. Multilayer clouds are found to persist throughout the year, among which cumulus and stratocumulus dominate the low clouds and cirrus dominates the high clouds. A combination of passive stereo-technique (MISR) and radiometric technique (ISCPP) captures the multilayer cloud structure as revealed by active sensor CALIOP. Coexistence of low clouds throughout the year with high aerosol concentration beneath and above leads to a transition from increasing to decreasing cloud fraction with an increase in aerosol optical depth. Such transition is rapid in the monsoon season due to convergence of low clouds to form high clouds facilitated by high aerosol loading. Further, the regional climate model RegCM 4.1 has been used to examine aerosol-cloud interaction. The aerosol-induced changes of low cloud amount are under-estimated by the model. The observation-based seasonal climatology of aerosol and cloud fields presented here may help in improving the model simulations of cloud variability and associated rainfall.

Dey, Sagnik; Sengupta, Kamalaika; Basil, George; Das, Sushant; Nidhi, Nidhi; Dash, S. K.; Sarkar, Arjya; Srivastava, Parul; Singh, Ajit; Agarwal, P.

2012-11-01

229

LIRAD Observations of Tropical Cirrus Clouds in MCTEX. Part II: Optical Properties and Base Cooling in Dissipating Storm Anvil Clouds  

Microsoft Academic Search

During the Maritime Continent Thunderstorm Experiment (MCTEX), several decaying storm anvils were observed. The anvil clouds exhibited typical patterns of fallout and decay over a number of hours of observation. The anvil bases were initially very attenuating to lidar pulses, and continued that way until anvil breakup commenced. During that time, the anvil base reached some characteristic altitude (7 km)

C. M. R. Platt; R. T. Austin; S. A. Young; A. J. Heymsfield

2002-01-01

230

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

231

Using SEVIRI radiances to retrieve cloud optical properties of convective cloud systems  

NASA Astrophysics Data System (ADS)

In this case study the development of cloud properties (cloud optical depth, effective radius and cloud top height) during the life-cycle of a convective cloud system over Europe was analyzed. To retrieve the properties we developed a retrieval scheme based on the radiative transfer code MOMO and an optimal estimation procedure. Input data are the visible to short-wavelength infrared channels from SEVIRI. In contrast to many other retrieval schemes we used 4 channels simultaneously. Especially the 3,9?m channel provides additional information due to the fact that it measures solar reflectance and thermal emission and allows the inclusion of cloud top height into the retrieval. By using a time series of SEVIRI measurements we want to provide and examine the microphysical development of the cloud over life-time. We monitored the growth of the system and found the most active parts of the convection with the highest water content and optical depth in those regions where the cloud top height is largest, too. The effective radius of the cloud particles is largest in older regions of the cloud system, where the cloud is already decaying.

Müller, Jennifer; Fischer, Jürgen; Hünerbein, Anja; Deneke, Hartwig; Macke, Andreas

2013-05-01

232

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

233

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

E-print Network

Evaluation of Cloud-Phase Retrieval Methods for SEVIRI on Meteosat-8 Using Ground-Based Lidar and Cloud Radar Data ERWIN L. A. WOLTERS, ROBERT A. ROEBELING, AND ARNOUT J. FEIJT Royal Netherlands 2007) ABSTRACT Three cloud-phase determination algorithms from passive satellite imagers are explored

Stoffelen, Ad

234

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

235

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

236

The Atmospheric Infrared Sounder version 6 cloud products  

NASA Astrophysics Data System (ADS)

The version 6 cloud products of the Atmospheric Infrared Sounder (AIRS) and Advanced Microwave Sounding Unit (AMSU) instrument suite are described. The cloud top temperature, pressure, and height and effective cloud fraction are now reported at the AIRS field-of-view (FOV) resolution. Significant improvements in cloud height assignment over version 5 are shown with FOV-scale comparisons to cloud vertical structure observed by the CloudSat 94 GHz radar and the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP). Cloud thermodynamic phase (ice, liquid, and unknown phase), ice cloud effective diameter (De), and ice cloud optical thickness (?) are derived using an optimal estimation methodology for AIRS FOVs, and global distributions for 2007 are presented. The largest values of ? are found in the storm tracks and near convection in the tropics, while De is largest on the equatorial side of the midlatitude storm tracks in both hemispheres, and lowest in tropical thin cirrus and the winter polar atmosphere. Over the Maritime Continent the diurnal variability of ? is significantly larger than for the total cloud fraction, ice cloud frequency, and De, and is anchored to the island archipelago morphology. Important differences are described between northern and southern hemispheric midlatitude cyclones using storm center composites. The infrared-based cloud retrievals of AIRS provide unique, decadal-scale and global observations of clouds over portions of the diurnal and annual cycles, and capture variability within the mesoscale and synoptic scales at all latitudes.

Kahn, B. H.; Irion, F. W.; Dang, V. T.; Manning, E. M.; Nasiri, S. L.; Naud, C. M.; Blaisdell, J. M.; Schreier, M. M.; Yue, Q.; Bowman, K. W.; Fetzer, E. J.; Hulley, G. C.; Liou, K. N.; Lubin, D.; Ou, S. C.; Susskind, J.; Takano, Y.; Tian, B.; Worden, J. R.

2014-01-01

237

The Atmospheric Infrared Sounder Version 6 cloud products  

NASA Astrophysics Data System (ADS)

The Version 6 cloud products of the Atmospheric Infrared Sounder (AIRS) and Advanced Microwave Sounding Unit (AMSU) instrument suite are described. The cloud top temperature, pressure, and height and effective cloud fraction are now reported at the AIRS field of view (FOV) resolution. Significant improvements in cloud height assignment over Version 5 are shown with pixel-scale comparisons to cloud vertical structure observed by the CloudSat 94 GHz radar and the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP). Cloud thermodynamic phase (ice, liquid, and unknown phase), ice cloud effective diameter (De), and ice cloud optical thickness (?) are derived using an optimal estimation methodology for AIRS FOVs, and global distributions for January 2007 are presented. The largest values of ? are found in the storm tracks and near convection in the Tropics, while De is largest on the equatorial side of the midlatitude storm tracks in both hemispheres, and lowest in tropical thin cirrus and the winter polar atmosphere. Over the Maritime Continent the diurnal cycle of ? is significantly larger than for the total cloud fraction, ice cloud frequency, and De, and is anchored to the island archipelago morphology. Important differences are described between northern and southern hemispheric midlatitude cyclones using storm center composites. The infrared-based cloud retrievals of AIRS provide unique, decadal-scale and global observations of clouds over the diurnal and annual cycles, and captures variability within the mesoscale and synoptic scales at all latitudes.

Kahn, B. H.; Irion, F. W.; Dang, V. T.; Manning, E. M.; Nasiri, S. L.; Naud, C. M.; Blaisdell, J. M.; Schreier, M. M.; Yue, Q.; Bowman, K. W.; Fetzer, E. J.; Hulley, G. C.; Liou, K. N.; Lubin, D.; Ou, S. C.; Susskind, J.; Takano, Y.; Tian, B.; Worden, J. R.

2013-06-01

238

A storm surge intensity classification based on extreme water level and concomitant wave height  

NASA Astrophysics Data System (ADS)

Storm surge is one of the predominant natural threats to coastal communities. Qingdao is located on the southern coast of the Shandong Peninsula in China. The storm surge disaster in Qingdao depends on various influencing factors such as the intensity, duration, and route of the passing typhoon, and thus a comprehensive understanding of natural coastal hazards is essential. In order to make up the defects of merely using the warning water level, this paper presents two statistical distribution models (Poisson Bi-variable Gumbel Logistic Distribution and Poisson Bi-variable Log-normal Distribution) to classify the intensity of storm surge. We emphasize the joint return period of typhoon-induced water levels and wave heights measured in the coastal area of Qingdao since 1949. The present study establishes a new criterion to classify the intensity grade of catastrophic storms using the typhoon surge estimated by the two models. A case study demonstrates that the new criterion is well defined in terms of probability concept, is easy to implement, and fits well the calculation of storm surge intensity. The procedures with the proposed statistical models would be useful for the disaster mitigation in other coastal areas influenced by typhoons.

Dong, Sheng; Gao, Junguo; Li, Xue; Wei, Yong; Wang, Liang

2015-04-01

239

Geometric data perturbation-based personal health record transactions in cloud computing.  

PubMed

Cloud computing is a new delivery model for information technology services and it typically involves the provision of dynamically scalable and often virtualized resources over the Internet. However, cloud computing raises concerns on how cloud service providers, user organizations, and governments should handle such information and interactions. Personal health records represent an emerging patient-centric model for health information exchange, and they are outsourced for storage by third parties, such as cloud providers. With these records, it is necessary for each patient to encrypt their own personal health data before uploading them to cloud servers. Current techniques for encryption primarily rely on conventional cryptographic approaches. However, key management issues remain largely unsolved with these cryptographic-based encryption techniques. We propose that personal health record transactions be managed using geometric data perturbation in cloud computing. In our proposed scheme, the personal health record database is perturbed using geometric data perturbation and outsourced to the Amazon EC2 cloud. PMID:25767826

Balasubramaniam, S; Kavitha, V

2015-01-01

240

Geometric Data Perturbation-Based Personal Health Record Transactions in Cloud Computing  

PubMed Central

Cloud computing is a new delivery model for information technology services and it typically involves the provision of dynamically scalable and often virtualized resources over the Internet. However, cloud computing raises concerns on how cloud service providers, user organizations, and governments should handle such information and interactions. Personal health records represent an emerging patient-centric model for health information exchange, and they are outsourced for storage by third parties, such as cloud providers. With these records, it is necessary for each patient to encrypt their own personal health data before uploading them to cloud servers. Current techniques for encryption primarily rely on conventional cryptographic approaches. However, key management issues remain largely unsolved with these cryptographic-based encryption techniques. We propose that personal health record transactions be managed using geometric data perturbation in cloud computing. In our proposed scheme, the personal health record database is perturbed using geometric data perturbation and outsourced to the Amazon EC2 cloud.

Balasubramaniam, S.; Kavitha, V.

2015-01-01

241

Ice clouds over Fairbanks, Alaska  

NASA Astrophysics Data System (ADS)

Arctic clouds have been recognized long ago as one of the key elements modulating the global climate system. They have gained much interest in recent years because the availability of new continuous datasets is opening doors to explore cloud and aerosol properties as never before. This is particularly important in the light of current climate change studies that predict changing weather scenarios around the world. This research investigates the occurrence and properties of a few types of ice clouds over the Arctic region with datasets available through the Arctic Facility for Atmospheric Remote Sensing (AFARS; 64.86° N, 147.84° W). This study exclusively focuses on ice clouds that form in the upper (cirrus clouds) and midlevels of the troposphere, and that are transparent to laser pulses (visible optical depth, tau < 3.0 -- 4.0). Cirrus clouds are ice-dominated clouds that are formed in the upper levels of the troposphere and are relatively thin such that their visual appearances range from bluish to gray in color. Mid-level ice clouds are those clouds primarily composed of ice crystals forming in the midlevels of the troposphere. It is hypothesized that unlike the basic midlevel cloud type (altostratus), other varieties of midlevel ice clouds exist at times over the Arctic region. The midlevel ice clouds studied here are also transparent to laser pulses and sometimes appear as a family of cirrus clouds to a surface observer. Because of their intermediate heights of occurrence in the troposphere, these could have microphysical properties and radiative effects that are distinct from those associated with upper level ice clouds in the troposphere. A ground-based lidar dataset with visual observations for identifying cloud types collected at AFARS over eight years is used to investigate this hypothesis. Cloud types over AFARS have been identified by a surface observer (Professor Kenneth Sassen) using established characteristics traits. Essential macrophysical properties of the clouds are derived from the lidar data, which serves as a climatological representation for the visually identified cirrus and mid-level ice clouds over a typical sub-Arctic location. Synoptic-scale weather patterns conducive for such cloud type formations are derived using a clustering technique applied to a re-analysis dataset. The cloud properties derived from ground-based lidar over AFARS are used to assess the cloud observations from the CALIPSO satellite.

Kayetha, Vinay Kumar

242

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

243

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

244

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

NASA Astrophysics Data System (ADS)

The 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

245

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

246

A Cloud Computing Based Patient Centric Medical Information System  

NASA Astrophysics Data System (ADS)

This chapter discusses an emerging concept of a cloud computing based Patient Centric Medical Information System framework that will allow various authorized users to securely access patient records from various Care Delivery Organizations (CDOs) such as hospitals, urgent care centers, doctors, laboratories, imaging centers among others, from any location. Such a system must seamlessly integrate all patient records including images such as CT-SCANS and MRI'S which can easily be accessed from any location and reviewed by any authorized user. In such a scenario the storage and transmission of medical records will have be conducted in a totally secure and safe environment with a very high standard of data integrity, protecting patient privacy and complying with all Health Insurance Portability and Accountability Act (HIPAA) regulations.

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

247

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

248

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

249

Limitations on Space-based Air Fluorescence Detector Apertures obtained from IR Cloud Measurements  

NASA Technical Reports Server (NTRS)

The presence of clouds between an airshower and a space-based detector can dramatically alter the measured signal characteristics due to absorption and scattering of the photonic signals. Furthermore, knowledge of the cloud cover in the observed atmosphere is needed to determine the instantaneous aperture of such a detector. Before exploring the complex nature of cloud-airshower interactions, we examine a simpler issue. We investigate the fraction of ultra-high energy cosmic ray events that may be expected to occur in volumes of the viewed atmosphere non-obscured by clouds. To this end, we use space-based IR data in concert with Monte Carlo simulated 10(exp 20) eV airshowers to determine the acceptable event fractions. Earth-observing instruments, such as MODIS, measure detailed cloud configurations via a CO2-slicing technique that can be used to determine cloud-top altitudes over large areas. Thus, events can be accepted if their observed 3-dimensional endpoints occur above low clouds as well as from areas of cloud-free atmosphere. An initial analysis has determined that by accepting airshowers that occur above low clouds, the non-obscured acceptance can be increased by approximately a factor of 3 over that obtained using a cloud-free criterion.

White, Nicholas E. (Technical Monitor); Krizmanic, John; Sokolsky, Pierre; Streitmatter, Robert

2003-01-01

250

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

251

Geometric and optical properties of cirrus clouds inferred from three-year ground-based lidar and CALIOP measurements over Seoul, Korea  

NASA Astrophysics Data System (ADS)

This study examines cirrus cloud top and bottom heights (CTH and CBH, respectively) and the associated optical properties revealed by ground-based lidar in Seoul (SNU-L), Korea, and space-borne Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), which were obtained during a three-year measurement period between July 2006 and June 2009. From two selected cases, we determined good agreement in CTH and CBH with cirrus cloud optical depth (COD) between ground-based lidar and space-borne CALIOP. In particular, CODs at a wavelength of 532 nm calculated from the three years of SNU-L and CALIOP measurements were 0.417 ± 0.394 and 0.425 ± 0.479, respectively. The fraction of COD lower than 0.1 was approximately 17% and 25% of the total SNU-L and CALIOP profiles, respectively, and approximately 50% of both lidar profiles were classified as sub-visual or optically thin such that COD was < 0.3. The mean depolarization ratio was estimated to be 0.30 ± 0.06 for SNU-L and 0.34 ± 0.08 for CALIOP. The monthly variation of CODs from SNU-L and CALIOP measurements was not distinct, whereas cirrus altitudes from both SNU-L and CALIOP showed distinct monthly variation. CALIOP observations showed that cirrus clouds reached the tropopause level in all months, whereas the up-looking SNU-L did not detect cirrus clouds near the tropopause in summer due to signal attenuation by underlying optically thick clouds. The cloud layer thickness (CLT) and COD showed a distinct linear relationship up to approximately 2 km of the CLT; however, the COD did not increase, but remained constant when the CLT was greater than 2.0 km. The ice crystal content, lidar signal attenuation, and the presence of multi-layered cirrus clouds may have contributed to this tendency.

Kim, Yumi; Kim, Sang-Woo; Kim, Man-Hae; Yoon, Soon-Chang

2014-03-01

252

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

253

The variability of tropical ice cloud properties as a function of the large-scale context from ground-based radar-lidar observations over Darwin, Australia  

NASA Astrophysics Data System (ADS)

The high complexity of cloud parameterizations now held in models puts more pressure on observational studies to provide useful means to evaluate them. One approach to the problem put forth in the modelling community is to evaluate under what atmospheric conditions the parameterizations fail to simulate the cloud properties and under what conditions they do a good job. It is the ambition of this paper to characterize the variability of the statistical properties of tropical ice clouds in different tropical "regimes" recently identified in the literature to aid the development of better process-oriented parameterizations in models. For this purpose, the statistical properties of non-precipitating tropical ice clouds over Darwin, Australia are characterized using ground-based radar-lidar observations from the Atmospheric Radiation Measurement (ARM) Program. The ice cloud properties analysed are the frequency of ice cloud occurrence, the morphological properties (cloud top height and thickness), and the microphysical and radiative properties (ice water content, visible extinction, effective radius, and total concentration). The variability of these tropical ice cloud properties is then studied as a function of the large-scale cloud regimes derived from the International Satellite Cloud Climatology Project (ISCCP), the amplitude and phase of the Madden-Julian Oscillation (MJO), and the large-scale atmospheric regime as derived from a long-term record of radiosonde observations over Darwin. The vertical variability of ice cloud occurrence and microphysical properties is largest in all regimes (1.5 order of magnitude for ice water content and extinction, a factor 3 in effective radius, and three orders of magnitude in concentration, typically). 98 % of ice clouds in our dataset are characterized by either a small cloud fraction (smaller than 0.3) or a very large cloud fraction (larger than 0.9). In the ice part of the troposphere three distinct layers characterized by different statistically-dominant microphysical processes are identified. The variability of the ice cloud properties as a function of the large-scale atmospheric regime, cloud regime, and MJO phase is large, producing mean differences of up to a factor 8 in the frequency of ice cloud occurrence between large-scale atmospheric regimes and mean differences of a factor 2 typically in all microphysical properties. Finally, the diurnal cycle of the frequency of occurrence of ice clouds is also very different between regimes and MJO phases, with diurnal amplitudes of the vertically-integrated frequency of ice cloud occurrence ranging from as low as 0.2 (weak diurnal amplitude) to values in excess of 2.0 (very large diurnal amplitude). Modellers should now use these results to check if their model cloud parameterizations are capable of translating a given atmospheric forcing into the correct statistical ice cloud properties.

Protat, A.; Delanoë, J.; May, P. T.; Haynes, J.; Jakob, C.; O'Connor, E.; Pope, M.; Wheeler, M. C.

2011-08-01

254

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

255

Cloud Computing System Based on Trusted Computing Platform  

Microsoft Academic Search

Cloud computing provides people a way to share large mount of distributed resources belonging to different organizations. That is a good way to share many kinds of distributed resources, but it also makes security problems more complicate and more important for users than before. In this paper, we analyze some security requirements in cloud computing environment. Since the security problems

Zhidong Shen; Li Li; Fei Yan; Xiaoping Wu

2010-01-01

256

Architectures for autonomic service management in cloud-based systems  

Microsoft Academic Search

The complexity of cloud systems poses new in- frastructure and application management challenges. One of the common goals of the research community, practitioners and vendors is to design self-adaptable solutions capable to react to unpredictable workload fluctuations and changing utility principles. This paper analyzes the problem from the perspective of an application service provider that uses a cloud infrastructure to

E. Casalicchio; L. Silvestri

2011-01-01

257

Cloud Privacy Audit Framework: A Value-Based Design  

ERIC Educational Resources Information Center

The rapid expansion of cloud technology provides enormous capacity, which allows for the collection, dissemination and re-identification of personal information. It is the cloud's resource capabilities such as these that fuel the concern for privacy. The impetus of these concerns are not to far removed from those expressed by Mason in 1986…

Coss, David Lewis

2013-01-01

258

Cloud Phase Determination Using Ground-Based AERI Observations at SHEBA  

SciTech Connect

A new technique for ascertaining the thermodynamic cloud phase from high-spectral-resolution ground-based infrared measurements made by the Atmospheric Emitted Radiance Interferometer (AERI) is presented. This technique takes advantage of the differences in the index of refraction of ice and water between 11 and 19 micrometers. The differences in the refractive indices translate into differences in cloud emissivity at the various wavelengths, which are used to determine whether clouds contain only ice particles or only water particles, or are mixed phase. Simulations demonstrate that the algorithm is able to ascertain correctly the cloud phase under most conditions, with the exceptions occurring when the optical depth of the cloud is dominated by liquid water (>70%). Several examples from the Surface Heat Budget of the Arctic Ocean (SHEBA) experiment are presented, to demonstrate the capability of the algorithm, in which a collocated polarization-sensitive lidar is used to provide insight to the true thermodynamic phase of the clouds. Statistical comparisons with this lidar during the SHEBA campaign demonstrate that the algorithm identifies the cloud as either an ice or mixed-phase cloud approximately 80% of time when a single-layer cloud with an average depolarization above 10% exists that is not opaque to the AERI. For single-layer clouds having depolarization of less than 10%, the algorithm identifies the cloud as a liquid water cloud over 50% of the time. This algorithm was applied to 7 months of data collected during SHEBA, and monthly statistics on the frequency of ice, water, and mixed-phase clouds are presented.

Turner, David D.; Ackerman, S. A.; Baum, B. A.; Revercomb, Henry E.; Yang, P.

2003-06-01

259

Cloud parameters using Ground Based Remote Sensing Systems and Satellites over urban coastal area  

NASA Astrophysics Data System (ADS)

Determining cloud radiative and microphysical properties are very important as a means to assess their effect on earths energy balance. While MODIS and GOES have been used for estimating cloud properties, assessing cloud properties directly has been difficult due the lack of consistent ground based sensor measurements except in such established places such as the ARM site in Oklahoma. However, it is known that significant aerosol seeding from urban and/or maritime sources can modify cloud properties such as effective radius and cloud optical depth and therefore evaluation of satellite retrievals in such a unique area offers novel opportunities to assess the potential of satellite retrievals to distinguish these mechanisms In our study, we used a multi-filter rotating shadow band radiometer (MFRSR) and micro wave radiometer (MWR) to retrieve the cloud optical depth and cloud droplets effective radius . In particular, we make a statistical study during summer 2013 where water phase clouds dominate and assess the accuracy of both MODIS and GOES satellite cloud products including LWP, COD and Reff. Most importantly, we assess performance against satellite observing geometries. Much like previous studies at the ARM site, we observe significant biases in the effective radius when the solar zenith angle is too large. In addition, we show that biases are also sensitive to the LWP limiting such measurement s in assessing potential aerosol-cloud signatures Finally, we discuss preliminary aerosol-cloud interactions from our ground system where local lidar is used to assess aerosols below clouds and explore the Aerosol Cloud Index.

Han, Z. T.; Gross, B.; Moshary, F.; Wu, Y.; Ahmed, S. A.

2013-12-01

260

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

261

Preliminary results of measurements by automated probes Vega 1 and 2 or particle concentration in clouds of Venus at heights 47-63 KM  

NASA Technical Reports Server (NTRS)

Results of the preliminary processing of the Vega 1 and 2 descender data on the cloud layer structure of the Venusian atmosphere are discussed. A photoelectric counter for aerosol particles is described together with its optical and pneumatic circuits and operation algorithm. Vertical profiles of concentrations of particles with a diameter of 0.4 microns agree quantitatively with the Pioneer-Venus and Venera 9 and 10 data. Concentrations of these particles are: in the B layer, up to 190/cu cm; in the C layer, up to 10/cu cm; and in the D layer, up to 130/cu cm. Layers have sharp boundaries with a significant vertical heterogeneity of the aerosol concentration field inside them.

Zhulanov, Y. V.; Mukhin, L. M.; Nenarokov, D. F.

1986-01-01

262

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

263

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 to offload computation and execute applications remotely. A mobile device should judiciously decide whether consider a mobile cloud computing (MCC) interaction system consisting of multiple mobile devices

Pedram, Massoud

264

Secure and Scalable Cloud-based Architecture for e-Health Wireless sensor networks  

E-print Network

Secure and Scalable Cloud-based Architecture for e-Health Wireless sensor networks Ahmed Lounis--There has been a host of research works on wireless sensor networks for medical applications. However to achieve high flexibility and performance. Keywords: wireless sensor networks, healthcare, cloud com

Paris-Sud XI, Université de

265

A Pareto-based GA for Scheduling HPC Applications on Distributed Cloud Infrastructures  

E-print Network

A Pareto-based GA for Scheduling HPC Applications on Distributed Cloud Infrastructures Yacine of a geographically distributed cloud computing infrastructure. We also pro- pose a greedy heuristic that aims infrastructures are included. In the same year, the aggregate electricity bill for operating those servers

Boyer, Edmond

266

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 is that large cloud data centres consume large amounts of energy and produce significant carbon footprints that minimise energy consumption while guaranteeing Service Level Agreements (SLAs). In order to achieve

Schneider, Jean-Guy

267

Shape-based Recognition of 3D Point Clouds in Urban Environments Aleksey Golovinskiy  

E-print Network

Shape-based Recognition of 3D Point Clouds in Urban Environments Aleksey Golovinskiy Princeton investigates the design of a system for rec- ognizing objects in 3D point clouds of urban environments lights, stop signs, etc.) are useful for numerous applications: city planning, emergency response

Funkhouser, Thomas A.

268

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

269

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

270

Distinguishing cirrus cloud presence in autonomous lidar measurements  

NASA Astrophysics Data System (ADS)

Level 2 Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) satellite-based cloud datasets from 2012 are investigated for metrics that help distinguish the cirrus cloud presence of in autonomous lidar measurements, using temperatures, heights, optical depth and phase. A thermal threshold, proposed by Sassen and Campbell (2001; SC2001) for cloud top temperature Ttop ? -37 °C, is evaluated vs. CALIOP algorithms that identify ice-phase cloud layers alone using depolarized backscatter. Global mean cloud top heights (11.15 vs. 10.07 km a.m.s.l.), base heights (8.76 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 these competing constraints. 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 phase estimates, Ttop ? -37 °C proves stable for distinguishing cirrus, as opposed to the risks of glaciated liquid water cloud contamination occurring in a given sample from clouds identified at warmer temperatures. Uncertainties in temperature profiles use to collocate with lidar data (i.e., model reanalyses/sondes) may justifiably relax the Ttop ? -37 °C threshold to include warmer cases. The ambiguity of "warm" (Ttop > -37 °C) ice cloud genus cannot be reconciled completely with available measurements, however, conspicuously including phase. Cloud top heights and optical depths are evaluated as potential constraints, as functions of CALIOP-retrieved phase. However, these data provide, at best, additional constraint in regional samples, compared with temperature alone, and may exacerbate classification uncertainties overall globally.

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

2014-07-01

271

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

272

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

273

Comparison between two algorithms based on different wavelets to obtain the Planetary Boundary Layer height  

NASA Astrophysics Data System (ADS)

Comprehension about the behavior of the Planet Boundary Layer (PBL) is an important factor in several fields, from analysis about air quality until modeling. However, monitoring the PBL evolution is a complex problem, because few instruments can provide continuous atmospheric measurements with enough spatial and temporal resolution. Inside this scenario lidar systems appear as an important tool, because it complies with all these capabilities- However, PBL observations are not a direct measure, being necessary to use complex mathematic algorithms. Recently, wavelet covariance transforms have been applied in this field. The objective of this work is to compare the performing of distinct types of algorithms: a structured on Haar wavelet and other based on first derivative of Gaussian and Mexican Hat wavelets, and the results were compared with two Hysplit modelling. For this aim, two campaigns were carried out. From the results were possible to infer that both algorithms provide coherent results as the expected, but the Haar algorithm separates the sub-layers more efficiently, so it is the most appropriate to complex situations.

de Arruda Moreira, Gregori; da Silva Lopes, Fabio J.; Guerrero-Rascado, Juan L.; Granados-Muñoz, Maria José; Bourayou, Riad; Landulfo, Eduardo

2014-10-01

274

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

275

Cloud-based preoperative planning for total hip arthroplasty: a study of accuracy, efficiency, and compliance.  

PubMed

As digital radiography becomes more prevalent, several systems for digital preoperative planning have become available. The purpose of this study was to evaluate the accuracy and efficiency of an inexpensive, cloud-based digital templating system, which is comparable with acetate templating. However, cloud-based templating is substantially faster and more convenient than acetate templating or locally installed software. Although this is a practical solution for this particular medical application, regulatory changes are necessary before the tremendous advantages of cloud-based storage and computing can be realized in medical research and clinical practice. PMID:22868590

Maratt, Joseph D; Srinivasan, Ramesh C; Dahl, William J; Schilling, Peter L; Urquhart, Andrew G

2012-08-01

276

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

277

Ground-based millimeter wave cloud profiling radar system (CPRS)  

SciTech Connect

The proposed Cloud Profiling Radar System (CPRS) is a two frequency (35 GHz, 95 GHz) polarimetric radar with a single reflector-lens antenna. The system will be used to perform three dimensional Doppler and polarimetric measurements on clouds. The various subsystems are currently being developed and this report gives technical details about the status of these subsystems. This report also updates other research activities. 7 figs.

McIntosh, R.E.; Pazmany, A.L.; Mead, J.B.

1991-08-01

278

Ground-based millimeter wave Cloud Profiling Radar System (CPRS)  

NASA Astrophysics Data System (ADS)

The proposed Cloud Profiling Radar System (CPRS) is a two frequency (35 GHz, 95 GHz) polarimetric radar with a single reflector-lens antenna. The system will be used to perform three dimensional Doppler and polarimetric measurements on clouds. The various subsystems are currently being developed and this report gives technical details about the status of these subsystems. This report also updates other research activities.

McIntosh, R. E.; Pazmany, A. L.; Mead, J. B.

1991-08-01

279

A Leasing Instances Based Billing Model for Cloud Computing  

Microsoft Academic Search

\\u000a As a new technology in IT industry, cloud computing has been much focused by both academia and industry. And many topics in\\u000a cloud computing are under study. However, as one of the most important issue, billing and pricing has been not so much concerned.\\u000a In this paper, we propose a novel pay-per-use billing model that can be used for the

Qin Yuan; Zhixiang Liu; Junjie Peng; Xing Wu; Jiandun Li; Fangfang Han; Qing Li; Wu Zhang; Xinjin Fan; Shengyuan Kong

2011-01-01

280

A robust threshold-based cloud mask for the HRV channel of MSG SEVIRI  

NASA Astrophysics Data System (ADS)

A robust threshold-based cloud mask for the high-resolution visible (HRV) channel (1 × 1 km2) of the METEOSAT SEVIRI instrument is introduced and evaluated. It is based on operational EUMETSAT cloud mask for the low resolution channels of SEVIRI (3 × 3 km2), which is used for the selection of suitable thresholds to ensure consistency with its results. The aim of using the HRV channel is to resolve small-scale cloud structures which cannot be detected by the low resolution channels. We find that it is of advantage to apply thresholds relative to clear-sky reflectance composites, and to adapt the threshold regionally. Furthermore, the accuracy of the different spectral channels for thresholding and the suitability of the HRV channel are investigated for cloud detection. The case studies show different situations to demonstrate the behaviour for various surface and cloud conditions. Overall, between 4 and 24% of cloudy low-resolution SEVIRI pixels are found to contain broken clouds in our test dataset depending on considered region. Most of these broken pixels are classified as cloudy by EUMETSAT's cloud mask, which will likely result in an overestimate if the mask is used as estimate of cloud fraction.

Bley, S.; Deneke, H.

2013-03-01

281

A novel cost based model for energy consumption in cloud computing.  

PubMed

Cloud data centers consume enormous amounts of electrical energy. To support green cloud computing, providers also need to minimize cloud infrastructure energy consumption while conducting the QoS. In this study, for cloud environments an energy consumption model is proposed for time-shared policy in virtualization layer. The cost and energy usage of time-shared policy were modeled in the CloudSim simulator based upon the results obtained from the real system and then proposed model was evaluated by different scenarios. In the proposed model, the cache interference costs were considered. These costs were based upon the size of data. The proposed model was implemented in the CloudSim simulator and the related simulation results indicate that the energy consumption may be considerable and that it can vary with different parameters such as the quantum parameter, data size, and the number of VMs on a host. Measured results validate the model and demonstrate that there is a tradeoff between energy consumption and QoS in the cloud environment. Also, measured results validate the model and demonstrate that there is a tradeoff between energy consumption and QoS in the cloud environment. PMID:25705716

Horri, A; Dastghaibyfard, Gh

2015-01-01

282

A Novel Cost Based Model for Energy Consumption in Cloud Computing  

PubMed Central

Cloud data centers consume enormous amounts of electrical energy. To support green cloud computing, providers also need to minimize cloud infrastructure energy consumption while conducting the QoS. In this study, for cloud environments an energy consumption model is proposed for time-shared policy in virtualization layer. The cost and energy usage of time-shared policy were modeled in the CloudSim simulator based upon the results obtained from the real system and then proposed model was evaluated by different scenarios. In the proposed model, the cache interference costs were considered. These costs were based upon the size of data. The proposed model was implemented in the CloudSim simulator and the related simulation results indicate that the energy consumption may be considerable and that it can vary with different parameters such as the quantum parameter, data size, and the number of VMs on a host. Measured results validate the model and demonstrate that there is a tradeoff between energy consumption and QoS in the cloud environment. Also, measured results validate the model and demonstrate that there is a tradeoff between energy consumption and QoS in the cloud environment. PMID:25705716

Horri, A.; Dastghaibyfard, Gh.

2015-01-01

283

Effect of Clouds on Apertures of Space-based Air Fluorescence Detectors  

NASA Technical Reports Server (NTRS)

Space-based ultra-high-energy cosmic ray detectors observe fluorescence light from extensive air showers produced by these particles in the troposphere. Clouds can scatter and absorb this light and produce systematic errors in energy determination and spectrum normalization. We study the possibility of using IR remote sensing data from MODIS and GOES satellites to delimit clear areas of the atmosphere. The efficiency for detecting ultra-high-energy cosmic rays whose showers do not intersect clouds is determined for real, night-time cloud scenes. We use the MODIS SST cloud mask product to define clear pixels for cloud scenes along the equator and use the OWL Monte Carlo to generate showers in the cloud scenes. We find the efficiency for cloud-free showers with closest approach of three pixels to a cloudy pixel is 6.5% exclusive of other factors. We conclude that defining a totally cloud-free aperture reduces the sensitivity of space-based fluorescence detectors to unacceptably small levels.

Sokolsky, P.; Krizmanic, J.

2003-01-01

284

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

285

Climatic impact of tropical lowland deforestation on nearby montane cloud forests.  

PubMed

Tropical montane cloud forests (TMCFs) depend on predictable, frequent, and prolonged immersion in cloud. Clearing upwind lowland forest alters surface energy budgets in ways that influence dry season cloud fields and thus the TMCF environment. Landsat and Geostationary Operational Environmental Satellite imagery show that deforested areas of Costa Rica's Caribbean lowlands remain relatively cloud-free when forested regions have well-developed dry season cumulus cloud fields. Further, regional atmospheric simulations show that cloud base heights are higher over pasture than over tropical forest areas under reasonable dry season conditions. These results suggest that land use in tropical lowlands has serious impacts on ecosystems in adjacent mountains. PMID:11641496

Lawton, R O; Nair, U S; Pielke Sr, R A; Welch, R M

2001-10-19

286

Lidar ratio and depolarization ratio for cirrus clouds.  

PubMed

We report on studies of the lidar and the depolarization ratios for cirrus clouds. The optical depth and effective lidar ratio are derived from the transmission of clouds, which is determined by comparing the backscattering signals at the cloud base and cloud top. The lidar signals were fitted to a background atmospheric density profile outside the cloud region to warrant the linear response of the return signals with the scattering media. An average lidar ratio, 29 +/- 12 sr, has been found for all clouds measured in 1999 and 2000. The height and temperature dependences ofthe lidar ratio, the optical depth, and the depolarization ratio were investigated and compared with results of LITE and PROBE. Cirrus clouds detected near the tropopause are usually optically thin and mostly subvisual. Clouds with the largest optical depths were found near 12 km with a temperature of approximately -55 degrees C. The multiple-scattering effect is considered for clouds with high optical depths, and this effect lowers the lidar ratios compared with a single-scattering condition. Lidar ratios are in the 20-40 range for clouds at heights of 12.5-15 km and are smaller than approximately 30 in height above 15 km. Clouds are usually optically thin for temperatures below approximately -65 degrees C, and in this region the optical depth tends to decrease with height. The depolarization ratio is found to increase with a height at 11-15 km and smaller than 0.3 above 16 km. The variation in the depolarization ratio with the lidar ratio was also reported. The lidar and depolarization ratios were discussed in terms of the types of hexagonal ice crystals. PMID:12396200

Chen, Wei-Nai; Chiang, Chih-Wei; Nee, Jan-Bai

2002-10-20

287

Assessment of variability in continental low stratiform clouds based on observations of radar reflectivity  

E-print Network

The variability of overcast low stratiform clouds observed over the ARM Climate Research Facility Southern Great Plains (ACRF SGP) site is analyzed, and an approach to characterizing subgrid variability based on assumed statistical distributions...

Kogan, Zena N.; Mechem, David B.; Kogan, Yefim L.

2005-09-22

288

Analytical estimation of droplet concentration at cloud base M. Pinsky,1  

E-print Network

Analytical estimation of droplet concentration at cloud base M. Pinsky,1 A. Khain,1 I. Mazin,2. Temperature dependencies of Smax and related quantities are analyzed. Citation: Pinsky, M., A. Khain, I. Mazin

Mark, Pinsky

289

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

290

Height control of laser metal-wire deposition based on iterative learning control and 3D scanning  

NASA Astrophysics Data System (ADS)

Laser Metal-wire Deposition is an additive manufacturing technique for solid freeform fabrication of fully dense metal structures. The technique is based on robotized laser welding and wire filler material, and the structures are built up layer by layer. The deposition process is, however, sensitive to disturbances and thus requires continuous monitoring and adjustments. In this work a 3D scanning system is developed and integrated with the robot control system for automatic in-process control of the deposition. The goal is to ensure stable deposition, by means of choosing a correct offset of the robot in the vertical direction, and obtaining a flat surface, for each deposited layer. The deviations in the layer height are compensated by controlling the wire feed rate on next deposition layer, based on the 3D scanned data, by means of iterative learning control. The system is tested through deposition of bosses, which is expected to be a typical application for this technique in the manufacture of jet engine components. The results show that iterative learning control including 3D scanning is a suitable method for automatic deposition of such structures. This paper presents the equipment, the control strategy and demonstrates the proposed approach with practical experiments.

Herali?, Almir; Christiansson, Anna-Karin; Lennartson, Bengt

2012-09-01

291

A resource management architecture based on complex network theory in cloud computing federation  

NASA Astrophysics Data System (ADS)

Cloud Computing Federation is a main trend of Cloud Computing. Resource Management has significant effect on the design, realization, and efficiency of Cloud Computing Federation. Cloud Computing Federation has the typical characteristic of the Complex System, therefore, we propose a resource management architecture based on complex network theory for Cloud Computing Federation (abbreviated as RMABC) in this paper, with the detailed design of the resource discovery and resource announcement mechanisms. Compare with the existing resource management mechanisms in distributed computing systems, a Task Manager in RMABC can use the historical information and current state data get from other Task Managers for the evolution of the complex network which is composed of Task Managers, thus has the advantages in resource discovery speed, fault tolerance and adaptive ability. The result of the model experiment confirmed the advantage of RMABC in resource discovery performance.

Zhang, Zehua; Zhang, Xuejie

2011-10-01

292

A Novel Approach to Generate Essential New CALIPSO-based Products: Biomass Burning Plume Injection Height Using CALIOP, MODIS and the NASA Langley Trajectory Model  

NASA Astrophysics Data System (ADS)

There is a significant connection between biomass burning (BB) emissions, the terrestrial environment and the atmosphere, which has strong implications for feedbacks to Air Quality and to the climate system. BB has the potential to alter numerous land and atmospheric processes and their full influence to feedback to interactive systems is currently being exposed (i.e. black carbon on spring Arctic ice). The heights to which BB emissions are injected influence their transport, their interaction with clouds, which alters albedo, and their ability to modify patterns of precipitation. We are working with our applications partners, primarily the Environmental Protection Agency and regional partners, to generate BB plume injection height products using multiple platforms, sensors and models (CALIOP, MODIS, NOAA HMS, Langley Trajectory Model) that will provide value to national and international scientific and air quality communities, the CALIPSO science and algorithm teams, and to public land, fire, and air quality management and regulations communities. Specifically, we are: (1) developing mean statistics that link CALIOP air parcels and BB injection height to the variables that control these dynamics, which include ecosystems, fire-specific and meteorological variables; and (2) defining the daily evolution of smoke plumes for specific fires. Statistics that link fire behavior and weather to plume rise are crucial for verifying and enhancing plume rise parameterization in regional- and global-scale models used for air quality, chemical transport and climate.

Vaughan, M.; Soja, A. J.; Fairlie, T. D.; Westberg, D. J.; Pouliot, G.

2012-12-01

293

Prediction based proactive thermal virtual machine scheduling in green clouds.  

PubMed

Cloud computing has rapidly emerged as a widely accepted computing paradigm, but the research on Cloud computing is still at an early stage. Cloud computing provides many advanced features but it still has some shortcomings such as relatively high operating cost and environmental hazards like increasing carbon footprints. These hazards can be reduced up to some extent by efficient scheduling of Cloud resources. Working temperature on which a machine is currently running can be taken as a criterion for Virtual Machine (VM) scheduling. This paper proposes a new proactive technique that considers current and maximum threshold temperature of Server Machines (SMs) before making scheduling decisions with the help of a temperature predictor, so that maximum temperature is never reached. Different workload scenarios have been taken into consideration. The results obtained show that the proposed system is better than existing systems of VM scheduling, which does not consider current temperature of nodes before making scheduling decisions. Thus, a reduction in need of cooling systems for a Cloud environment has been obtained and validated. PMID:24737962

Kinger, Supriya; Kumar, Rajesh; Sharma, Anju

2014-01-01

294

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

295

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

296

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

297

Buildings and Terrain of Urban Area Point Cloud Segmentation based on PCL  

NASA Astrophysics Data System (ADS)

One current problem with laser radar point data classification is building and urban terrain segmentation, this paper proposes a point cloud segmentation method base on PCL libraries. PCL is a large cross-platform open source C++ programming library, which implements a large number of point cloud related efficient data structures and generic algorithms involving point cloud retrieval, filtering, segmentation, registration, feature extraction and curved surface reconstruction, visualization, etc. Due to laser radar point cloud characteristics with large amount of data, unsymmetrical distribution, this paper proposes using the data structure of kd-tree to organize data; then using Voxel Grid filter for point cloud resampling, namely to reduce the amount of point cloud data, and at the same time keep the point cloud shape characteristic; use PCL Segmentation Module, we use a Euclidean Cluster Extraction class with Europe clustering for buildings and ground three-dimensional point cloud segmentation. The experimental results show that this method avoids the multiple copy system existing data needs, saves the program storage space through the call of PCL library method and class, shortens the program compiled time and improves the running speed of the program.

Liu, Ying; Zhong, Ruofei

2014-03-01

298

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

299

Scale Dependence of Variability in Stratiform Clouds Based on Millimeter Wave Could Radar  

SciTech Connect

Internal variability of stratiform clouds is manifested on grid scales ranging from cloud resolving models to general circulation models, and its accurate formulation is one of the most important tasks in improvement of model predictions. Understanding cloud variability on different scales will help to develop and improve subgrid-scale cloud parameterizations. Information about variability is also crucial when dealing with retrieval of microphysical information from observations of volume averaged reflectivity parameters, since neglecting variability can lead to substantial biases in estimation of retrieved microphysical variables. The Atmospheric Radiation Measurement Program (ARM) operates millimeter wave cloud radar (MMCR) at the ARM Climate Research Facility over the Southern Great Plains (ACRF SGP) that provides a unique opportunity to obtain continuous observations in order to address issues of cloud variability. These data contain information on spatial and/or temporal short- and long-range correlations in cloudiness, enabling scale-by-scale (scaling) analyses over a range of hundreds of meters to hundreds of kilometers. The objective of this study is to conduct an analysis based on radar reflectivity observations of clouds over the ACRF SGP site with special emphasis on boundary layer clouds, and the effect of drizzle.

Kogan, Z.N.; Kogan, Y.L.; Mechem, D.B.

2005-03-18

300

Improvement in cloud predictions using satellite data assimilation for real-time forecasting  

NASA Astrophysics Data System (ADS)

The accuracy of quantitative forecasting of low-level operational cloud products such as the cloud top height, cloud top pressure and cloud thickness is rather low. Reliable forecasting of the low-level clouds (cloud top altitudes below 2-3 km) such as fog, stratus or stratocumulus is essential for aviation safety purposes. With the advent of an increased number of spectral channels and high-resolution imagers on the Geostationary Operational Environmental Satellite, cloud products can be diagnostically extracted and, furthermore, these cloud products can be used to modify the initial conditions for numerical weather prediction. Although operational methods are relatively successful in determining the cloud top altitudes for deep clouds and high clouds (usually above 5 km), there is no unique way of inferring the cloud top heights for low-level clouds due to their optical properties and low-level inversions. An algorithm has been developed in this study to classify the low-level cloud types using the brightness temperatures extracted from the GOES satellite visible and infrared channels. Cloud top temperatures above 8° C characterize low-level clouds. The brightness temperature differences between the window channel (11 ìm) and the shortwave infrared channel (4 ìm) are used to segregate the optically thin and thick clouds, and the relative humidity obtained from the surface stations is used to distinguish the fog or clouds formed by fog lifting. The infrared satellite imagery on 29 June 2006 is considered for this study with domain coverage of 400 x 400 km2 . The ground-truth observations were obtained from the surface weather station located at the Naval Air Station, Fallon (NASF), Nevada. Upon classification of low-level clouds in the satellite imagery, (a) the first step is to compute the cloud base temperature in the low-level cloudy pixels using the surface temperature and cloud base height obtained from the ceilometer measurements (at NASF) following a dry adiabatic lapse rate; (b) the second step is to compute the cloud top height using cloud base temperature, and the satellite- derived cloud top temperature following the wet adiabatic lapse rate in the cloud layer; (c) the third step is to obtain a representative lapse rate for the computing domain; (d) the fourth step is to compute the cloud top heights for the individual satellite pixels in the entire domain. The information on cloud top height and cloud top temperature obtained from the cloudy pixels is then dynamically assimilated into the model analysis using Cressman's objective analysis. Using the improved model analyses, a deterministic forecast will be carried out with an option of four-dimensional data assimilation of model winds and thermodynamic variables for a pre- forecast period of one complete diurnal cycle. Verification will be carried out using the hourly surface observations and cloud base measurements, and also using the satellite cloud imagery against the simulated cloud imagery and associated cloud products. The data assimilation of the derived cloud products is being tested in modeling systems such as the Mesoscale Model 5 (MM5) and the Weather Research Forecasting Model (WRF). The data assimilation of cloud products and verification is intended for the pre-processing module in a real-time forecasting system using various objective analysis procedures such as the Cressman-type, multi-quadric and 3DVAR. This study is to develop an efficient forecasting system to support naval aircraft and rotorcraft operations at the Fallon Naval Air Station, Fallon, Nevada.

Vellore, R.; Koracin, D.; Wetzel, M.

2006-12-01

301

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

302

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

303

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

304

A sensitivity-based approach to optimize the surface treatment of a low-height tramway noise barrier  

NASA Astrophysics Data System (ADS)

Transportation noise has become a main nuisance in urban areas, in the industrialized world and across the world, to the point that according to the World Health Organization 65% of the European population is exposed to excessive noise and 20% to night-time levels that may harm their health. There is therefore a need to find new ways to mitigate transportation noise in urban areas. In this work, a possible device to achieve this goal is studied: a low-height noise barrier. It consists of a barrier typically less than one meter high placed close to the source, designed to decrease significantly the noise level for nearby pedestrians and cyclists. A numerical method which optimizes the surface treatment of a low-height barrier in order to increase its insertion loss is presented. Tramway noise barriers are especially studied since the noise sources are in this case close to the ground and would be attenuated more by the barrier. The acoustic behavior of the surface treatment is modeled via its admittance. It can be itself described by a few parameters (flow resistivity, geometrical dimensions...), which can then be optimized. It is proposed to couple porous layers and micro-perforated panel (MPP) resonators in order to take advantage of their different acoustic properties. Moreover, the optimization is achieved using a sensitivity-based method, since in this framework the gradient of the attenuation can be evaluated accurately and efficiently. Several shapes are considered: half-cylinder, quarter-cylinder, straight wall, T-shape and square shape. In the case of a half-cylindrical geometry, a semi-analytical solution for the sound field in terms of a series of cylindrical waves is derived, which simplifies the sensitivity calculation and optimization process. The boundary element method (BEM) is used to evaluate the attenuation for the remaining shapes, and in this case the sensitivity is evaluated using the adjoint state approach. For all considered geometries, it is found that placing an absorbing treatment close to the source is indeed necessary to attenuate the multiple re ections happening between the tramway and the barrier, and that a tuned MPP resonator on the top of the barrier can yield better performance than a uniform absorbent treatment. More advanced numerical modeling and scale model measurements seem to confirm these results.

Jolibois, Alexandre

305

Classification of particle effective shape ratios in cirrus clouds based on the lidar depolarization ratio.  

PubMed

A shape classification technique for cirrus clouds that could be applied to future spaceborne lidars is presented. A ray-tracing code has been developed to simulate backscattered and depolarized lidar signals from cirrus clouds made of hexagonal-based crystals with various compositions and optical depth, taking into account multiple scattering. This code was used first to study the sensitivity of the linear depolarization rate to cloud optical and microphysical properties, then to classify particle shapes in cirrus clouds based on depolarization ratio measurements. As an example this technique has been applied to lidar measurements from 15 mid-latitude cirrus cloud cases taken in Palaiseau, France. Results show a majority of near-unity shape ratios as well as a strong correlation between shape ratios and temperature: The lowest temperatures lead to high shape ratios. The application of this technique to space-borne measurements would allow a large-scale classification of shape ratios in cirrus clouds, leading to better knowledge of the vertical variability of shapes, their dependence on temperature, and the formation processes of clouds. PMID:12148751

Noel, Vincent; Chepfer, Helene; Ledanois, Guy; Delaval, Arnaud; Flamant, Pierre H

2002-07-20

306

Flexible Process-Based Applications in Hybrid Clouds  

Microsoft Academic Search

Cloud applications target large costumer groups to leverage economies of scale. To increase the number of customers, a flexible application design is of major importance. It enables customers to adjust the application to their individual needs in a self-service manner. In this paper, we classify the required variability of these flexible applications: data variability - changes to handled data structures;

Christoph Fehling; Frank Leymann; David Schumm; Ralf Konrad; Ralph Mietzner; Michael Pauly

2011-01-01

307

Autonomic Cloud-based Operation of Massively Multiplayer Online Games  

E-print Network

operation offers and we show that considering compensations for SLA faults in the offer selection process market of over 24 billion dollars. Infrastructure-as-a-Service (IaaS) cloud computing promises to solve of Warcraft infrastructure(see http://kotaku.com/5050300/how-much- has-wow-cost-blizzard-since-2004). The Iaa

Iosup, Alexandru

308

Cloud computing based logistics resource dynamic integration and collaboration  

Microsoft Academic Search

In order to eliminate the information islands phenomenon and realize socialization resources integration in the development of logistics, a logistics resource dynamic integration framework oriented service collaboration combined of cloud computing technology was put forward from the logistics services value-added perspective. Some dispersed third party logistics company could be combined to form virtual logistics chain by virtue of this integration

Jia Gao; Jun Ma; Xiu Zhang; Di Lu

2012-01-01

309

Move It or Lose It: Cloud-Based Data Storage  

ERIC Educational Resources Information Center

There was a time when school districts showed little interest in storing or backing up their data to remote servers. Nothing seemed less secure than handing off data to someone else. But in the last few years the buzz around cloud storage has grown louder, and the idea that data backup could be provided as a service has begun to gain traction in…

Waters, John K.

2010-01-01

310

A new cloud-based hp finite element method  

Microsoft Academic Search

A hybrid computational method for solving boundary-value problems is introduced which combines features of the meshless hp-cloud methods with features of conventional finite elements. The method admits straightforward nonuniform hp-type approximations, easy implementation of essential boundary conditions, is robust under severe distortions of the mesh, and can deliver exponential rates of convergence. Results of numerical experiments are presented.

J. T. Oden; C. A. M. Duarte; O. C. Zienkiewicz

1998-01-01

311

Exploiting virtualization for delivering cloud-based IPTV services  

Microsoft Academic Search

Cloud computing is a new infrastructure environ- ment that delivers on the promise of supporting on-demand services in a flexible manner by scheduling bandwidth, storage and compute resources on the fly. IPTV services like Video On Demand (VoD) and Live broadcast TV requires substantial bandwidth and compute resources to meet the real time re- quirements and to handle the very

Vaneet Aggarwal; Xu Chen; Vijay Gopalakrishnan; Rittwik Jana; K. K. Ramakrishnan; Vinay A. Vaishampayan

2011-01-01

312

Essentials for CSPs to Succeed with Cloud-based Services  

E-print Network

-per-use subscriptions as an alternative to traditional packaged software licenses. From this limited perspective, cloud of which involves innovation for services, business models, and technology delivery methods. In today requirements including: robust, high-performance networks; strong customer relationships; application delivery

313

BlobCR: Virtual Disk Based Checkpoint-Restart for HPC Applications on IaaS Clouds  

E-print Network

BlobCR: Virtual Disk Based Checkpoint-Restart for HPC Applications on IaaS Clouds Bogdan Nicolaea-Champaign Abstract Infrastructure-as-a-Service (IaaS) cloud computing is gaining significant interest in in- dustry- life HPC application. Keywords: IaaS clouds, high performance computing, checkpoint-restart, fault

Boyer, Edmond

314

Learning Bayesian network structure using a cloud-based adaptive immune genetic algorithm  

NASA Astrophysics Data System (ADS)

A new BN structure learning method using a cloud-based adaptive immune genetic algorithm (CAIGA) is proposed. Since the probabilities of crossover and mutation in CAIGA are adaptively varied depending on X-conditional cloud generator, it could improve the diversity of the structure population and avoid local optimum. This is due to the stochastic nature and stable tendency of the cloud model. Moreover, offspring structure population is simplified by using immune theory to reduce its computational complexity. The experiment results reveal that this method can be effectively used for BN structure learning.

Song, Qin; Lin, Feng; Sun, Wei; Chang, KC

2011-06-01

315

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

316

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

317

Cloud Phase Determination Using Ground-Based AERI Observations at SHEBA  

Microsoft Academic Search

ABSTRACT A new,technique for ascertaining the thermodynamic,cloud phase from high-spectral-resolution ground-based infrared measurements,made,by the Atmospheric,Emitted Radiance Interferometer (AERI) is presented. This technique takes advantage,of the differences in the index of refraction of ice and water between,11 and 19 mm. The differences in the refractive indices translate into differences in cloud emissivity at the various wavelengths, which are used to determine

D. D. Turner; S. A. Ackerman; B. A. Baum; H. E. Revercomb; P. Yang

2003-01-01

318

Service specification in cloud environments based on extensions to open standards  

Microsoft Academic Search

Cloud computing technologies are changing the way in which services are deployed and operated nowadays, introducing advantages such as a great degree of flexibility (e.g. pay-peruse models, automatic scalability, etc.). However, existing offerings (Amazon EC2, GoGrid, etc.) are based on proprietary service definition mechanisms, thus introducing vendor lock-in to the customers who deploy their services on those clouds. On the

Fermín Galán; Americo Sampaio; Luis Rodero-Merino; Irit Loy; Victor Gil; Luis M. Vaquero

2009-01-01

319

Cloud-computing-based framework for multi-camera topology inference in smart city sensing system  

Microsoft Academic Search

This paper proposes a cloud-computing-based algorithmic framework which is scalable and adaptive to online smart city video sensing system. One of the most cost-expensive works in such a system is to infer the topology structure of video camera network, thus spatio-temporal relationship inference for large-scale camera network is simulated on a cloud-computing platform to validate the proposed framework. The simulation

Ye Wen; Xiaokang Yang; Yi Xu

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

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

322

Standing adult human phantoms based on 10th, 50th and 90th mass and height percentiles of male and female Caucasian populations  

NASA Astrophysics Data System (ADS)

Computational anthropomorphic human phantoms are useful tools developed for the calculation of absorbed or equivalent dose to radiosensitive organs and tissues of the human body. The problem is, however, that, strictly speaking, the results can be applied only to a person who has the same anatomy as the phantom, while for a person with different body mass and/or standing height the data could be wrong. In order to improve this situation for many areas in radiological protection, this study developed 18 anthropometric standing adult human phantoms, nine models per gender, as a function of the 10th, 50th and 90th mass and height percentiles of Caucasian populations. The anthropometric target parameters for body mass, standing height and other body measures were extracted from PeopleSize, a well-known software package used in the area of ergonomics. The phantoms were developed based on the assumption of a constant body-mass index for a given mass percentile and for different heights. For a given height, increase or decrease of body mass was considered to reflect mainly the change of subcutaneous adipose tissue mass, i.e. that organ masses were not changed. Organ mass scaling as a function of height was based on information extracted from autopsy data. The methods used here were compared with those used in other studies, anatomically as well as dosimetrically. For external exposure, the results show that equivalent dose decreases with increasing body mass for organs and tissues located below the subcutaneous adipose tissue layer, such as liver, colon, stomach, etc, while for organs located at the surface, such as breasts, testes and skin, the equivalent dose increases or remains constant with increasing body mass due to weak attenuation and more scatter radiation caused by the increasing adipose tissue mass. Changes of standing height have little influence on the equivalent dose to organs and tissues from external exposure. Specific absorbed fractions (SAFs) have also been calculated with the 18 anthropometric phantoms. The results show that SAFs decrease with increasing height and increase with increasing body mass. The calculated data suggest that changes of the body mass may have a significant effect on equivalent doses, primarily for external exposure to organs and tissue located below the adipose tissue layer, while for superficial organs, for changes of height and for internal exposures the effects on equivalent dose are small to moderate.

Cassola, V. F.; Milian, F. M.; Kramer, R.; de Oliveira Lira, C. A. B.; Khoury, H. J.

2011-07-01

323

Impacts of cloud heterogeneities on cirrus optical properties retrieved from space-based thermal infrared radiometry  

NASA Astrophysics Data System (ADS)

This paper presents a study, based on simulations, of the impact of cirrus cloud heterogeneities on the retrieval of cloud parameters (optical thickness and effective diameter) for the Imaging Infrared Radiometer (IIR) on board CALIPSO. Cirrus clouds are generated by the stochastic model 3DCLOUD for two different cloud fields and for several averaged cloud parameters. One cloud field is obtained from a cirrus observed on 25 May 2007 during the airborne campaign CIRCLE-2 and the other is a cirrus uncinus. The radiative transfer is simulated with the 3DMCPOL code. To assess the errors due to cloud heterogeneities, two related retrieval algorithms are used: (i) the split-window technique to retrieve the ice crystal effective diameter and (ii) an algorithm similar to the IIR operational algorithm to retrieve the effective emissivity and the effective optical thickness. Differences between input parameters and retrieved parameters are compared as a function of different cloud properties such as the mean optical thickness, the heterogeneity parameter and the effective diameter. The optical thickness heterogeneity for each 1 km × 1 km observation pixel is represented by the optical thickness standard deviation computed using 100 m × 100 m subpixels. We show that optical thickness heterogeneity may have a strong impact on the retrieved parameters, mainly due to the plane-parallel approximation (PPA assumption). In particular, for cirrus clouds with ice crystal diameter of approximately 10 ?m, the averaged error on the retrieved effective diameter and optical thickness is about 2.5 ?m (~ 25%) and -0.20 (~ 12%), respectively. Then, these biases decrease with increasing effective size due to a decrease of the cloud absorption and, thus, the PPA bias. Cloud horizontal heterogeneity effects are greater than other possible sources of retrieval errors such as those due to cloud vertical heterogeneity impact, surface temperature or atmospheric temperature profile uncertainty and IIR retrieval uncertainty. Cloud horizontal heterogeneity effects are larger than the IIR retrieval uncertainty if the standard deviation of the optical thickness, inside the observation pixel, is greater than 1.

Fauchez, T.; Dubuisson, P.; Cornet, C.; Szczap, F.; Garnier, A.; Pelon, J.; Meyer, K.

2015-02-01

324

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

325

Measuring heights to crown base and crown median with LiDAR in a mature, even-aged loblolly pine stand  

E-print Network

Measuring heights to crown base and crown median with LiDAR in a mature, even-aged loblolly pine to measure the vertical distribution of canopy elements (mostly branches and leaves) directly over large-wing aircraft that emitted discrete laser pulses (904 nm wavelength) at 4 kHz. Since the direction of the laser

Cao, Quang V.

326

Self-adapting Applications Based on QA Requirements in the Cloud Using Market-Based Heuristics  

Microsoft Academic Search

\\u000a There are several situations where applications in the cloud need to self-manage their quality attributes (QA). We posit that\\u000a self-adaptation can be achieved through a market-based approach and describe a marketplace for web-services. We simulate agents\\u000a trading web-services on behalf of self-managing applications and demonstrate that such a mechanism leads to a good allocation\\u000a of web-services to applications, even when

Vivek Nallur; Rami Bahsoon

2010-01-01

327

A secure EHR system based on hybrid clouds.  

PubMed

Consequently, application services rendering remote medical services and electronic health record (EHR) have become a hot topic and stimulating increased interest in studying this subject in recent years. Information and communication technologies have been applied to the medical services and healthcare area for a number of years to resolve problems in medical management. Sharing EHR information can provide professional medical programs with consultancy, evaluation, and tracing services can certainly improve accessibility to the public receiving medical services or medical information at remote sites. With the widespread use of EHR, building a secure EHR sharing environment has attracted a lot of attention in both healthcare industry and academic community. Cloud computing paradigm is one of the popular healthIT infrastructures for facilitating EHR sharing and EHR integration. In this paper, we propose an EHR sharing and integration system in healthcare clouds and analyze the arising security and privacy issues in access and management of EHRs. PMID:22351166

Chen, Yu-Yi; Lu, Jun-Chao; Jan, Jinn-Ke

2012-10-01

328

Estimating Aircraft Heading Based on Laserscanner Derived Point Clouds  

NASA Astrophysics Data System (ADS)

Using LiDAR sensors for tracking and monitoring an operating aircraft is a new application. In this paper, we present data processing methods to estimate the heading of a taxiing aircraft using laser point clouds. During the data acquisition, a Velodyne HDL-32E laser scanner tracked a moving Cessna 172 airplane. The point clouds captured at different times were used for heading estimation. After addressing the problem and specifying the equation of motion to reconstruct the aircraft point cloud from the consecutive scans, three methods are investigated here. The first requires a reference model to estimate the relative angle from the captured data by fitting different cross-sections (horizontal profiles). In the second approach, iterative closest point (ICP) method is used between the consecutive point clouds to determine the horizontal translation of the captured aircraft body. Regarding the ICP, three different versions were compared, namely, the ordinary 3D, 3-DoF 3D and 2-DoF 3D ICP. It was found that 2-DoF 3D ICP provides the best performance. Finally, the last algorithm searches for the unknown heading and velocity parameters by minimizing the volume of the reconstructed plane. The three methods were compared using three test datatypes which are distinguished by object-sensor distance, heading and velocity. We found that the ICP algorithm fails at long distances and when the aircraft motion direction perpendicular to the scan plane, but the first and the third methods give robust and accurate results at 40m object distance and at ~12 knots for a small Cessna airplane.

Koppanyi, Z.; Toth, C., K.

2015-03-01

329

Barrier height enhancement of InP-based n-Ga(0.47)In(0.53)As Schottky-barrier diodes grown by molecular beam epitaxy  

NASA Technical Reports Server (NTRS)

Barrier height enhancement of an InP-based p(+)n-Ga(0.47)In(0.53)As Schottky diode grown by MBE has been demonstrated for infra-red photodetector applications. A barrier height of 0.35 eV for n-Ga(0.47)In(0.53)As Schottky barrier diodes, was increased to the effective barrier height of 0.55 eV, with a p(+)-Ga(0.47)In(0.53)As surface layer of 30 nm thick. The results show a reverse leakage current density of 0.0015 A/sq cm and a junction capacitance of 0.3 pF, which are comparable to those of p-Ga(0.47)In(0.53)As Schottky-barrier diodes at a reverse bias voltage of 5 V.

Kim, J. H.; Li, S. S.; Figueroa, L.

1988-01-01

330

Nowcasting of cloud cover with MSG  

NASA Astrophysics Data System (ADS)

In this poster, an algorithm is shown to detect water and ice clouds seperately and forecast their developement for the next timesteps. It is based on Meteosat SEVIRI (Spinning Enhanced Visible and Infrared Imager) data from almost all channels with a timestep of 15 minutes. In order to derive cloud cover, optical depth and height of ice clouds the "Cirrus Optical properties derived from CALIOP and SEVIRI during day and night" (COCS) algorithm (Kox 2012) was used. For the determination of water clouds a cloud mask was developed. For a most accurate forecast the detected clouds are divided into two groups, convective and advective, and afterwards treated seperately. The forecast of advective clouds basically takes place with the pyramidal matcher ("optical flow" technique, Zinner et al. 2008) by determining a motion vector field from two consecutive images. The clouds are then classified as objects with similar properties (optical depth, temperature) and a forecast for each object separately is then performed. For the detection of convective clouds the tracking and nowcasting algorithm Cb-TRAM (CumulonimBus TRacking And Monitoring, Zinner et al. 2008) is used, which divides convection into three stages. The further development und thus the forecast of these clouds is dependent of the current stage. Appications to selected case studies will be shown.

Sirch, Tobias; Bugliaro, Luca

2014-05-01

331

2D Radiative Processes Near Cloud Edges  

NASA Technical Reports Server (NTRS)

Because of the importance and complexity of dynamical, microphysical, and radiative processes taking place near cloud edges, the transition zone between clouds and cloud free air has been the subject of intense research both in the ASR program and in the wider community. One challenge in this research is that the one-dimensional (1D) radiative models widely used in both remote sensing and dynamical simulations become less accurate near cloud edges: The large horizontal gradients in particle concentrations imply that accurate radiative calculations need to consider multi-dimensional radiative interactions among areas that have widely different optical properties. This study examines the way the importance of multidimensional shortwave radiative interactions changes as we approach cloud edges. For this, the study relies on radiative simulations performed for a multiyear dataset of clouds observed over the NSA, SGP, and TWP sites. This dataset is based on Microbase cloud profiles as well as wind measurements and ARM cloud classification products. The study analyzes the way the difference between 1D and 2D simulation results increases near cloud edges. It considers both monochromatic radiances and broadband radiative heating, and it also examines the influence of factors such as cloud type and height, and solar elevation. The results provide insights into the workings of radiative processes and may help better interpret radiance measurements and better estimate the radiative impacts of this critical region.

Varnai, T.

2012-01-01

332

An independent evaluation of a South African hygroscopic cloud seeding experiment, 1991–1995  

Microsoft Academic Search

An independent statistical evaluation of a randomised hygroscopic cloud seeding experiment carried out in South Africa from 1991–1995 is presented, based on the original radar data for each storm. It is found that seeded storms clearly lasted longer than unseeded ones. It is suggested that the initiation of precipitation at a lower height in seeded than in unseeded clouds (demonstrated

E. K. Bigg

1997-01-01

333

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

334

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

335

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

336

Research of MPPT for photovoltaic generation based on two-dimensional cloud model  

NASA Astrophysics Data System (ADS)

The cloud model is a mathematical representation to fuzziness and randomness in linguistic concepts. It represents a qualitative concept with expected value Ex, entropy En and hyper entropy He, and integrates the fuzziness and randomness of a linguistic concept in a unified way. This model is a new method for transformation between qualitative and quantitative in the knowledge. This paper is introduced MPPT (maximum power point tracking, MPPT) controller based two- dimensional cloud model through analysis of auto-optimization MPPT control of photovoltaic power system and combining theory of cloud model. Simulation result shows that the cloud controller is simple and easy, directly perceived through the senses, and has strong robustness, better control performance.

Liu, Shuping; Fan, Wei

2013-03-01

337

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

338

Sensing Clouds via Spacecraft Radio Occultation Observations  

NASA Technical Reports Server (NTRS)

The presence of clouds dramatically alters the opacity and radiative transfer within Earth's atmosphere at both short and long wavelengths. Knowledge of cloud top and base is needed to estimate the Outgoing Long wave Radiation (OLR) to space and the net radiation at the surface from a given atmospheric profile. Satellite observations are required to provide the global perspective needed for climate. Cloud top pressure can be determined to some accuracy from spaceborne radiance measurements when cloud opacities are sufficiently large and cloud top temperatures are sufficiently low to readily them from the surface. Cloud base is particularly difficult to determine from space. The relatively small sensitivity of long wavelengths must be used to penetrate the clouds while at the same time providing sufficient sensitivity to detect the cloud base. We are studying the indirect sensitivity of radio occultation observations to clouds through their impact on the refractivity structure. The tradewind inversion is an excellent example where a very sharp refractivity structure coincides with the top of the tradewind cumulus and stratus clouds. In general, any cloud with sufficient IR opacity will have large transmissivity gradient at cloud top (base) which will result in large cooling (heating) which will create a thermal inversion at cloud top (base). Both liquid and ice clouds can reach this critical opacity. The thermal inversion and sharp change in specific humidity will cause a sharp change in the refractivity gradient which can be identified in the radio occultation results, particularly the signal amplitude. The occultations yield very accurate information on the height of such features. The heating at cloud base drives convection causing the air to follow a moist adiabat within the Cloud which further helps constrain the interpretation of the observations. The upward expansion of such opaque clouds due to convection may be an important mechanism supplying moisture into the upper troposphere. We will present simulations using high resolution radiosondes from field campaigns representing the expected signatures of such features. We will also present initial results of comparisons between GPS observations and GOES-derived cloud tops to assess the utility of this concept.

Kursinski, E. R.; Wu, F.; Limaye, S.; Wu, M.- L.

2000-01-01

339

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

340

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

341

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

342

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

343

Aerosol-cloud-drizzle interactions in warm boundary layer clouds using ground-based measurements from Atlantic and continental European sites  

NASA Astrophysics Data System (ADS)

Aerosol impacts the climate directly through scattering and absorbing radiation, and indirectly through altering properties of clouds and precipitation. With increasing ambient aerosol concentration, it is agreed that the redistribution of cloud water to more numerous, but smaller cloud droplets suppresses precipitation. However, the magnitude of precipitation suppression is uncertain, and the response of total cloud water to aerosol concentration remains poorly observed and understood. To better understand how aerosols regulate macro- and microphysical properties of boundary-layer clouds, and to establish statistical relationships of aerosol-cloud-precipitation interactions, we analyze high-temporal resolution observations from the Atmospheric Radiation Measurement (ARM) Mobile Facility deployments in Germany in 2007 and in the Azores during 2009-2010. Through synergy between ground-based aerosol observing systems, active and passive remote sensing instruments, we will show how the drizzle rate at cloud base varies with aerosol concentration. We will also demonstrate how the probability of precipitation and the precipitation susceptibility respond to ambient aerosol concentration, and whether these responses agree with results from state-of-the-art satellite observations and climate models.

Mann, Julian; Chiu, Christine; Hogan, Robin; O'Connor, Ewan

2013-04-01

344

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

345

An Actor-Centric, Asset-Based Monitor Deployment Model for Cloud Computing Uttam Thakore, Gabriel A. Weaver, and William H. Sanders  

E-print Network

of detecting intrusions. Keywords-cloud computing; monitor deployment; security; actor model; asset-based; cloud architecture; threat modeling I. INTRODUCTION Cloud computing introduces unique security risksAn Actor-Centric, Asset-Based Monitor Deployment Model for Cloud Computing Uttam Thakore, Gabriel A

Sanders, William H.

346

An assessment of MODIS marine boundary layer cloud property retrievals based on a Large-Eddy simulation  

NASA Astrophysics Data System (ADS)

The extensive and persistent marine boundary layer (MBL) clouds play a vital role in Earth’s radiative energy budget and have been suggested to be at the heart of tropical cloud feedback uncertainties in current GCMs. Improving our understanding of MBL clouds requires long-term satellite-based observations of these clouds and correct interpretation of the observation. Some recent studies show evidence that some microphysical processes, such as the drizzling and cloud top entrainment, may have an impact on MODIS cloud property retrievals. To identity the importance of these impacts, we have recently developed a framework to simulate MODIS operational retrievals from cloud fields simulated by a Large-Eddy model. In this research, we explore the possibilities of using this framework to help us understand the impacts of 3D effects, sub-pixel cloud heterogeneity, drizzle and cloud top entrainment on MODIS cloud effective radius and optical thickness retrievals. We are investigating how the 3D effects depend on the combination of MODIS bands selected for the retrieval. We are also investigating the impacts of vertical droplet size variation and the presence of drizzle on MODIS cloud effective radius retrieval. The strengths and limitations of this framework for understanding MODIS cloud product will also be discussed.

Zhang, Z.; Platnick, S. E.; Stevens, B. B.

2009-12-01

347

PREDICTING DIAMETER AT BREAST HEIGHT FROM TOTAL HEIGHT AND CROWN LENGTH  

E-print Network

201 PREDICTING DIAMETER AT BREAST HEIGHT FROM TOTAL HEIGHT AND CROWN LENGTH Quang V. Cao and Thomas. In this paper, we will examine alternative methods of predicting d.b.h. from total height and crown length (model 2a), or from total height, crown length, and number of trees per acre (model 2b), based

Cao, Quang V.

348

Scale-Invariant Vote-Based 3D Recognition and Registration from Point Clouds  

E-print Network

) The registered CAD model. data prior to inference makes such vote-based approaches more efficient and robust than and registration. (a) Real object, fabricated from a CAD model. (b) Point cloud extracted using a multi-view stereo scale, rotation and translation pose) detected in the volume. (e) Votes for the object centre, based

Martin, Ralph R.

349

Digital right management based on cloud computing and dynamic secure permission  

Microsoft Academic Search

In this paper, a novel digital rights management system based on cloud computing and dynamic secure permission is proposed, according to the problems existed in current DRM system and new requirements of consumes. This scheme embeds the second watermark which is jointly created by all the parties involved based on the Chinese remainder theorem, to realize reliable right tracing and

Li Fen; Liu Quan

2011-01-01

350

SLA-based Resource Provisioning for Software-as-a-Service Applications in Cloud Computing Environments  

E-print Network

1 / 30 SLA-based Resource Provisioning for Software-as-a-Service Applications in Cloud ComputingS providers need to establish a Service Level Agreement (SLA) to define the Quality of Service (QoS). The main). In this paper, we propose customer driven SLA- based resource provisioning algorithms to minimize cost

Buyya, Rajkumar

351

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

352

A cloud-based synthetic seismogram generator implemented using Windows Azure  

NASA Astrophysics Data System (ADS)

Synthetic seismograms generated by solving the seismic wave equation using numerical methods are being widely used in seismology. For fully three-dimensional seismic structure models, the generation of these synthetic seismograms may require large amount of computing resources. Conventional high-performance computer clusters may not provide a cost-effective solution to this type of applications. The newly emerging cloud-computing platform provides an alternative solution. In this paper, we describe our implementation of a synthetic seismogram generator based on the reciprocity principle using the Windows Azure cloud application framework. Our preliminary experiment shows that our cloud-based synthetic seismogram generator provides a cost-effective and numerically efficient approach for computing synthetic seismograms based on the reciprocity principle.

Chen, Po; Lee, En-Jui; Wang, Liqiang

2013-10-01

353

Royal Meteorological Society 1 INTRODUCTION TO CLOUDS  

E-print Network

later in this talk. Clouds composed of ice crystals are, by definition, high clouds. The height ranges cubic centimetre of cloud. · High clouds composed of ice crystals, in a variety of shapes and each about 100 m long. · Typically about ten ice crystals in every cubic centimetre of cloud

Allan, Richard P.

354

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

355

GEWEX Cloud System Study (GCSS) cirrus cloud working group: modelling case development based on 9 March 2000 ARM SGP observations  

NASA Astrophysics Data System (ADS)

The GCSS working group on cirrus focuses on inter-comparison of model simulations for models ranging from very detailed microphysical and dynamical models through to general circulation models (GCMs). In the previous GCSS inter-comparison, it was a surprise to the modeling community how much of a range there was in ice water path predictions by different cirrus models for such idealized cases. There was some grouping according to the complexity of models; however, there were no observations with which to distinguish between model performance. The aim of the current GCSS cirrus inter-comparison is to base the study on a rigorously observed case study. In this way, the case may be used to identify which models in the inter-comparison are performing well and highlight areas for model development as well as provide a base case for future models to compare against when being developed or when testing new developments within existing models. In this paper, we present the case development for the current GCSS working group study on cirrus cloud. This paper summarizes how the case was developed and based on the 9 March 2000 Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) intensive observation period (IOP). To our knowledge, this case offers the most detailed case study for cirrus comparison available, with extensive effort to derive the most appropriate large scale forcing as possible which is such a significant determinant of clouds. We anticipate this will offer significant improvement over past comparisons which have mostly been loosely based on observations. Notably this study makes use of retrievals of observations of ice water content, ice number concentration, and fall velocity, thus offering several constraints to evaluate model performance. The case study is developed utilizing various observations including ARM SGP remote sensing including the Millimeter cloud radar (MMCR), radiometers, radiosondes, aircraft observations, satellite observations, objective analysis and complemented with results from the Rapid Update Cycle (RUC) model output and bespoke gravity wave simulations using the 3-dimensional velocities over mountains (3DVOM) model. An initial modelling assessment of the case has been shown using the UK Met Office Large Eddy Simulation Model (LEM) which supports the use of this case for the full inter-comparison study.

Yang, H.; Dobbie, S.; Mace, G. G.; Ross, A.; Quante, M.

2011-10-01

356

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

357

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 % with some estimates of observed trends of 7 % or more. This would require the radiative effect of clouds to change from one that increases atmospheric radiative absorption by about to one that decreases it by . 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

2015-04-01

358

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

359

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

360

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

361

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

362

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

363

The comparative analysis based on maize integrated QTL map and meta-analysis of plant height QTLs  

Microsoft Academic Search

1201 published maize QTLs conferring for 68 traits were collected and imported into local C Map software to construct an integrated\\u000a QTL map, which can be used for marker-mining, QTL localization, gene cloning and marker-assisted selection. The maize integrated\\u000a QTL map showed that maize QTLs for various traits usually clustered in all chromosomes. 22 plant height QTLs of maize were

Yi Wang; Ji Yao; Zhengfeng Zhang; Yonglian Zheng

2006-01-01

364

Block-based cloud classification with statistical features and distribution of local texture features  

NASA Astrophysics Data System (ADS)

This work performs cloud classification on all-sky images. To deal with mixed cloud types in one image, we propose performing block division and block-based classification. In addition to classical statistical texture features, the proposed method incorporates local binary pattern, which extracts local texture features in the feature vector. The combined feature can effectively preserve global information as well as more discriminating local texture features of different cloud types. The experimental results have shown that applying the combined feature results in higher classification accuracy compared to using classical statistical texture features. In our experiments, it is also validated that using block-based classification outperforms classification on the entire images. Moreover, we report the classification accuracy using different classifiers including the k-nearest neighbor classifier, Bayesian classifier, and support vector machine.

Cheng, H.-Y.; Yu, C.-C.

2015-03-01

365

Block based cloud classification with statistical features and distribution of local texture features  

NASA Astrophysics Data System (ADS)

This work performs cloud classification on all-sky images. To deal with mixed cloud types in one image, we propose to perform block division and block based classification. In addition to classical statistical texture features, the proposed method incorporates local binary pattern, which extracts local texture features in the feature vector. The combined feature can effectively preserve global information as well as more discriminating local texture features of different cloud types. The experimental results have shown that applying the combined feature results in higher classification accuracy compared to using classical statistical texture features. In our experiments, it is also validated that using block-based classification outperforms classification on the entire images. Moreover, we report the classification accuracy using different classifiers including k-nearest neighbor classifier, Bayesian classifier, and support vector machine in this paper.

Cheng, H.-Y.; Yu, C.-C.

2014-11-01

366

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

367

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

368

Observation of clouds with an airborne DOAS instrument  

NASA Astrophysics Data System (ADS)

We report on observations of clouds with the CARIBIC (Civil Aircraft for Regular Investigation of the atmosphere Based on an Instrument Container) using a DOAS (Differential Optical Absorption Spectroscopy) instrument. The CARIBIC container is regularly installed on a Lufthansa Airbus retrofitted with a three probe inlet (water, aerosols and trace gases). The inlet also contains three small telescopes for the DOAS instrument observing the column densities of oxygen dimers (O4) and additional trace gases like NO2, HCHO or HONO. During frequent traverses of smaller clouds enhancements of O4 are seen; however, the focus of the presentation will be on a cloud event over the Caribbean. During one flight from Frankfurt to Caracas (Venezuela) when the CARIBIC airbus penetrated a large convective cloud over the Caribbean Sea; at this occasion the DOAS instrument observed strongly enhanced column densities of O4 associated with a strong increase in the Ring effect (filling in of the Fraunhofer lines caused by elastic scattering). At the same time the in situ cloud water instrument measured a strong enhancement of cloud water. The observations are compared with results of a 3-D Monte Carlo Radiative transfer Model to estimate the cloud optical thickness (? 160) and the cloud top height (15 km). The high optical density of the cloud enhanced multiple scattering and thereby the light path was extended up to about 100 km inside the cloud. Thereby not only the cloud optical properties can be estimated but also the trace gas concentration inside the cloud.

Heue, K.-P.; Brenninkmeijer, C.; Walter, D.; Wagner, T.; Zahn, A.; Deutschmann, T.; Platt, U.

2012-04-01

369

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

370

A path loss model with height variation in residential area based on experimental and theoretical studies using a 5G\\/2G dual band antenna  

Microsoft Academic Search

An efficient approach to revealing the propagation characteristics for broadband mobile services in the 5-GHz microwave band is to utilize the existing 2-GHz band propagation data accumulated by many researchers. This paper presents the height variation characteristics at 5.2-GHz compared with that at 2.2-GHz in a residential area based on experiments and theoretical analysis. Propagation measurements were carried out using

N. Kita; Akio Sato; Masahiro Umehira

2000-01-01

371

Microwave and Millimeter Wave Characteristics and Attenuation of Clouds over some Malaysian Equatorial Stations  

NASA Astrophysics Data System (ADS)

Based on radar range height indicator (RHI) measurements, cloud characteristics in relation to radiowave propagation over three locations in different geographical region in western Malaysia have been presented. It is seen that low cloud occurrence over these locations are quite significant. Cloud attenuation and noise temperature can result in serious degradation of telecommunication link performances. This paper presents cloud coverage in different months, 0°C isotherm height and cloud attenuation results at 12 GHz, 20 GHz, 36 GHz, 50 GHz, 70 GHz and 100 GHz over measurement site. The low level cloud over the measurement sites has been found to occur for many days and nights and particularly in the months of April to May and October to December. Such results are useful for satellite communication and remote sensing application in Malaysia.

Mandeep, J. S.; Hassan, S. I. S.

2008-03-01

372

A Comparative Study and Evaluation of Mixing-Height Estimation Based on Sodar-RASS, Ceilometer Data and Numerical Model Simulations  

NASA Astrophysics Data System (ADS)

A comparative study and evaluation of mixing-layer height estimation was conducted, using data from remote sensing and in-situ instrumentation, radiosondes, synoptic analyses and model simulations. The data were collected during an experimental campaign conducted at the Athens International Airport, Greece, from 15 to 26 September 2007. Mixing-layer height from the sodar dataset was estimated taking into account the backscatter signal, temperature, Richardson number profiles and surface-based measurements, while for the ceilometer data, the optical attenuated aerosol backscatter intensity first derivative was utilized. Numerical simulations using the Penn State/NCAR MM5 numerical mesoscale model and the Weather Research and Forecast numerical model were also performed. Comparative results under different meteorological conditions (local flows, moderate to strong background flows) are presented and discussed. According to our results under moderate to strong winds the existing mechanical turbulence creates good signal conditions for the two remote systems leading to a good overall agreement between the two methodologies, while both models give reliable estimations of the mixing height. The sodar-RASS system is more suitable under low to moderate winds or when local flows are developed with weak stability, while the ceilometer system is more suitable for moderate to strong winds, which is associated with a homogeneous atmosphere and weaker low-level temperature inversions. In the models, the existing approach for atmospheric boundary-layer depth simulation usually provides higher compared to remote sensing values, especially during local flow events. An alternative approach for the estimation of mixing height by the models, the estimation and use of the diffusion coefficient profiles, is a promising methodology regarding the comparison with the sodar-RASS mixing-height estimations.

Helmis, C. G.; Sgouros, G.; Tombrou, M.; Schäfer, K.; Münkel, C.; Bossioli, E.; Dandou, A.

2012-12-01

373

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

374

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

375

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

376

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

377

A sensor fusion method for tracking vertical velocity and height based on inertial and barometric altimeter measurements.  

PubMed

A sensor fusion method was developed for vertical channel stabilization by fusing inertial measurements from an Inertial Measurement Unit (IMU) and pressure altitude measurements from a barometric altimeter integrated in the same device (baro-IMU). An Extended Kalman Filter (EKF) estimated the quaternion from the sensor frame to the navigation frame; the sensed specific force was rotated into the navigation frame and compensated for gravity, yielding the vertical linear acceleration; finally, a complementary filter driven by the vertical linear acceleration and the measured pressure altitude produced estimates of height and vertical velocity. A method was also developed to condition the measured pressure altitude using a whitening filter, which helped to remove the short-term correlation due to environment-dependent pressure changes from raw pressure altitude. The sensor fusion method was implemented to work on-line using data from a wireless baro-IMU and tested for the capability of tracking low-frequency small-amplitude vertical human-like motions that can be critical for stand-alone inertial sensor measurements. Validation tests were performed in different experimental conditions, namely no motion, free-fall motion, forced circular motion and squatting. Accurate on-line tracking of height and vertical velocity was achieved, giving confidence to the use of the sensor fusion method for tracking typical vertical human motions: velocity Root Mean Square Error (RMSE) was in the range 0.04-0.24 m/s; height RMSE was in the range 5-68 cm, with statistically significant performance gains when the whitening filter was used by the sensor fusion method to track relatively high-frequency vertical motions. PMID:25061835

Sabatini, Angelo Maria; Genovese, Vincenzo

2014-01-01

378

A Sensor Fusion Method for Tracking Vertical Velocity and Height Based on Inertial and Barometric Altimeter Measurements  

PubMed Central

A sensor fusion method was developed for vertical channel stabilization by fusing inertial measurements from an Inertial Measurement Unit (IMU) and pressure altitude measurements from a barometric altimeter integrated in the same device (baro-IMU). An Extended Kalman Filter (EKF) estimated the quaternion from the sensor frame to the navigation frame; the sensed specific force was rotated into the navigation frame and compensated for gravity, yielding the vertical linear acceleration; finally, a complementary filter driven by the vertical linear acceleration and the measured pressure altitude produced estimates of height and vertical velocity. A method was also developed to condition the measured pressure altitude using a whitening filter, which helped to remove the short-term correlation due to environment-dependent pressure changes from raw pressure altitude. The sensor fusion method was implemented to work on-line using data from a wireless baro-IMU and tested for the capability of tracking low-frequency small-amplitude vertical human-like motions that can be critical for stand-alone inertial sensor measurements. Validation tests were performed in different experimental conditions, namely no motion, free-fall motion, forced circular motion and squatting. Accurate on-line tracking of height and vertical velocity was achieved, giving confidence to the use of the sensor fusion method for tracking typical vertical human motions: velocity Root Mean Square Error (RMSE) was in the range 0.04–0.24 m/s; height RMSE was in the range 5–68 cm, with statistically significant performance gains when the whitening filter was used by the sensor fusion method to track relatively high-frequency vertical motions. PMID:25061835

Sabatini, Angelo Maria; Genovese, Vincenzo

2014-01-01

379

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

380

Spectrum Clouds: A Session Based Spectrum Trading System for Multi-hop Cognitive Radio Networks  

E-print Network

Spectrum Clouds: A Session Based Spectrum Trading System for Multi-hop Cognitive Radio Networks, Taiwan. Abstract--Spectrum trading creates more accessing opportu- nities for secondary users (SUs) and economically benefits the primary users (PUs). However, it is challenging to implement spectrum trading

Latchman, Haniph A.

381

POSTER: Temporal Attribute-Based Encryption in Clouds , Hongxin Hu3  

E-print Network

POSTER: Temporal Attribute-Based Encryption in Clouds Yan Zhu1,2 , Hongxin Hu3 , Gail-Joon Ahn3 University, Tempe, AZ 85287, USA {yan.zhu,smchen}@pku.edu.cn,{hxhu,gahn}@asu.edu ABSTRACT There has been

Duchowski, Andrew T.

382

Management-based License Discovery for the Cloud Minkyong Kim, Han Chen, Jonathan Munson, Hui Lei  

E-print Network

Management-based License Discovery for the Cloud Minkyong Kim, Han Chen, Jonathan Munson, Hui Lei by the vendor's terms and conditions for that soft- ware. Vendors reserve the right to audit an organization. For this reason, organizations go to great expense to maintain a complete and accurate inventory of their software

Kim, Minkyong

383

A Deep Investigation Into Network Performance in Virtual Machine Based Cloud Environments  

E-print Network

and detailed system analysis reveal that the performance variation and degradation are mainly due to the dualA Deep Investigation Into Network Performance in Virtual Machine Based Cloud Environments Ryan Shea in the hypervisor level and present concrete solutions. Such remedies have been implemented and evaluated in our

Liu, Jiangchuan (JC)

384

Combinatorial Auction-Based Allocation of Virtual Machine Instances in Clouds  

E-print Network

. INTRODUCTION Cloud computing enables individuals and small to medium enterprises satisfy their computational fixed-price allo- cation mechanisms. We argue that combinatorial auction-based allocation mechanisms are especially efficient over the fixed-price mechanisms since the virtual machine instances are assigned

Grosu, Daniel

385

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

386

Research on producer service innovation in home-textile industrial cluster based on cloud computing platform  

Microsoft Academic Search

This paper aims to explore the cloud computing based service innovation in home textile industrial clusters, which is regarded as a service system. Firstly, the challenges facing home textile industrial clusters (industrial upgrading, structural adjustment, and brand building & management) are analyzed. Secondly, the producer services in the cluster service system are studied. Moreover, it is proposed that the producer

KeJing Zhang; Biao Ma; PingJun Dong; BingYong Tang; Hong Cai

2010-01-01

387

Efficient LDPC Code Based Secret Sharing Schemes and Private Data Storage in Cloud without Encryption  

E-print Network

Efficient LDPC Code Based Secret Sharing Schemes and Private Data Storage in Cloud without in the past few years. By employing the underlying ideas of efficient Belief Propagation (BP) decoding process in LDPC and LT codes, this paper introduces three classes of secret sharing schemes called BP-XOR secret

Wang, Yongge

388

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

389

Research on library management system for CDs attached to books based on Cloud Computing  

Microsoft Academic Search

Nowadays, all of library management systems for CDs attached to books are running independently: independent devices, independent systems, and making CD images independently. That brings huge waste of investment and labor. In this paper, we redesign the management system for CDs attached to books based on Cloud Computing. By comparing and analyzing the two systems, we can see that the

Honghai Kan; Zhimin Yang; Yue Wang; Nana Qi

2010-01-01

390

Arctic Mixed-Phase Cloud Properties Derived from Surface-Based Sensors Matthew D. Shupe1  

E-print Network

Program's ongoing measurements at the North Slope of Alaska (NSA) site in Barrow, Alaska since spring SHEBA and NSA measurements. IDENTIFYING AND CHARACTERIZING MIXED-PHASE CLOUDS Ground-based instruments and humidity. The instrument suites at both the SHEBA and NSA sites were nearly identical, except that the NSA

Shupe, Matthew

391

COMPARISON OF AMV CLOUD TOP PRESSURE DERIVED FROM MSG WITH SPACE BASED LIDAR OBSERVATIONS (CALIPSO)  

E-print Network

COMPARISON OF AMV CLOUD TOP PRESSURE DERIVED FROM MSG WITH SPACE BASED LIDAR OBSERVATIONS (CALIPSO all CTHs from MSG (CLA box and AMV) and CALIOP. However, the AMV pressure allocation is systematically of the HA methods to several atmospheric parameters. Meteosat Second Generation (MSG) provides many new

Madeleine, Jean-Baptiste