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1

Cloud base height survey based on stereo image  

NASA Astrophysics Data System (ADS)

Cloud observation is an important factor for weather application and change of cloud base height plays a vital role in development of future weather system. Aim at requirement of cloud observation, a method on survey of cloud base height (CBH) is proposed based on stereo image. The main contents include image match and calculation of CBH which makes use of forward intersection of photogrammetry. It overcomes discontinuity, strong subjectivity and qualitative analysis of traditional eye observation. By application of National Day's weather safeguard, it tests that method of stereo imaging surveying is a way of direct measurement with better precision and is possible in technology also.

Li, Guosheng; Lin, Zongjian; Ma, Shuqing; Zhi, Xiaodong

2011-06-01

2

Development of methods for inferring cloud thickness and cloud-base height from satellite radiance data  

NASA Technical Reports Server (NTRS)

Cloud-top height is a major factor determining the outgoing longwave flux at the top of the atmosphere. The downwelling radiation from the cloud strongly affects the cooling rate within the atmosphere and the longwave radiation incident at the surface. Thus, determination of cloud-base temperature is important for proper calculation of fluxes below the cloud. Cloud-base altitude is also an important factor in aircraft operations. Cloud-top height or temperature can be derived in a straightforward manner using satellite-based infrared data. Cloud-base temperature, however, is not observable from the satellite, but is related to the height, phase, and optical depth of the cloud in addition to other variables. This study uses surface and satellite data taken during the First ISCCP Regional Experiment (FIRE) Phase-2 Intensive Field Observation (IFO) period (13 Nov. - 7 Dec. 1991, to improve techniques for deriving cloud-base height from conventional satellite data.

Smith, William L., Jr.; Minnis, Patrick; Alvarez, Joseph M.; Uttal, Taneil; Intrieri, Janet M.; Ackerman, Thomas P.; Clothiaux, Eugene

1993-01-01

3

Behavior of cloud base height from ceilometer measurements  

NASA Astrophysics Data System (ADS)

Given the importance of clouds in the climate, and the difficulty in determining their behavior and their contribution to climate change, there is a need for improvement of methods for automatic and continuous description of cloud characteristics. Ceilometers constitute a priori a reliable instrumental method for sounding the atmosphere and describing cloudiness, specifically cloud base height (CBH), cloud cover, and even cloud vertical structure. In the present study, the behavior of CBH at different time scales has been investigated at Girona (Spain) including a statistical analysis of the frequency distributions of CBH. The study covers four years (2007-2010) of high resolution (both in time and in the vertical direction) ceilometer measurements. At this location, ceilometer measurements reveal a seasonal cycle, with important differences between "extreme" seasons (winter and summer) and the "transition" seasons (spring and autumn). Summer months in general and July in particular behave quite differently than other periods in the year, both regarding the presence of clouds (with a minimum cloud occurrence of about 20-30%) and the distribution of CBH (with more than 25% of clouds having CBH around 1400 m and 80% of clouds with CBH lower than 3000 m). The distributions of CBH are explained on the basis of some atmospheric situations that generate clouds, in particular conditions that produce the large number of low level clouds found.

Costa-Surós, M.; Calbó, J.; González, J. A.; Martin-Vide, J.

2013-06-01

4

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

NASA Astrophysics Data System (ADS)

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

Pan, L.; Lu, D.

2012-12-01

5

A case study of stratus cloud base height multifractal fluctuations  

Microsoft Academic Search

The complex structure of a typical stratus cloud base height (or profile) time series is analyzed with respect to the variability of its fluctuations and their correlations at all experimentally observed temporal scales. Due to the underlying processes that create these time series, they are expected to have multiscaling properties. For obtaining reliable measures of these scaling properties, different methods

K. Ivanova; H. N. Shirer; E. E. Clothiaux; N. Kitova; M. A. Mikhalev; T. P. Ackerman; M. Ausloos

2002-01-01

6

Experimental optoelectronic model of ceilometer for cloud base height measurement  

NASA Astrophysics Data System (ADS)

Experimental determination of cloud base height (CBH) by a passive monostatic method by means of opto-electronic ceilometer model was carried out. The model of a ceilometer is two black-and-white CCD-cameras having closest sighting lines. Focal lengths for optical systems of used television cameras were selected for the possibility of measuring the CBH from 50 to 1500 m. Obtained by cameras the pictures with different scale images of selected for measure of cloudiness fragments are digitized on computer and are processed. The algorithm for determining the CBH using the proposed model of ceilometer is described and results of experimental measurements are shown.

Zuev, S. V.; Krasnenko, N. P.

2009-02-01

7

Determination of cloud base height using the passive monostatic method  

NASA Astrophysics Data System (ADS)

Among passive methods for a cloud base height (CBH) detection, bistatic and monostatic methods are known. In the first case a triangulation method with two photodetectors is used. A drawback of this method is a need in obtaining images of the one overcast fragment by two spatially separated cameras in the course of shot time. In consequence, images have different view angles and the problem of identification of this fragment appears. The passive monostatic method for CBH detection does not have these demerits. For measurement by this method, linear sizes of object should be known. But for a case of CBH detection it is impossible, because cloudiness can change in the course of short time. The offered method does not demand knowledge about linear sizes of cloudiness fragments. The method uses dependence of scale change of object image at change of focal length of camera lens depending on distance up to object.

Zuev, S. V.; Krasnenko, N. P.

2008-02-01

8

A new approach to retrieve cloud base height of marine boundary layer clouds  

NASA Astrophysics Data System (ADS)

novel approach for estimating marine boundary layer cloud base height (CBH) is proposed based on calculated boundary layer lapse rates, collocated cloud top height (CTH), cloud top, and ocean surface temperatures from the A-Train satellite constellation. The method takes advantage of the assumption that decreases of temperature within and below water clouds may follow the different constant apparent lapse rates in the same region, respectively. The CBHs derived from the new method compare well with the coincident CBH product from the active sensors of Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) and CloudSat. The correlation coefficient, the mean difference, and the standard deviation are 0.79 (0.54), 0.02 km (0.03 km), and ±0.35 km (±0.54 km), respectively, when CTH is derived from CALIPSO data (or Moderate Resolution Imaging Spectroradiometer retrieval). Besides the relatively small bias, the most important advantage of this method compared to previous CBH retrieval techniques is that it is independent of boundary layer cloud types, optical thickness, and illumination.

Li, J. M.; Yi, Y. H.; Stamnes, K.; Ding, X. D.; Wang, T. H.; Jin, H. C.; Wang, S. S.

2013-08-01

9

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

10

Relationship between cloud base height retrieved from lidar and downward longwave irradiance  

NASA Astrophysics Data System (ADS)

Downward longwave radiation is a key process to understand the climate change, energy budget, and water cycle at the earth's surface. Cloud is a dominant factor to determine the intensity of longwave radiation. It is widely known that cloud cover and cloud base height (CBH) have strong effects on the downward longwave radiation, however there are not so many studies regarding the quantitative evaluation of relationship between cloud properties and downward longwave radiation. The intent of the present study is to quantify the impact of cloud property on the downward longwave irradiance (DLI). We used the data obtained with CGR-4 pyrgeometer at Tateno, Japan for the period from January 2002 to December 2011. Cloud radiative contribution fraction (CRC) is evaluated with a ratio of the difference of DLI between observation under cloudy sky without precipitation and calculation assumed clear-sky condition to the observed DLI. The difference between calculation and observation is -4.60+/-3.00 W/m2, and the calculation method reproduced to observation. Cloud is classified into three types by CBH, low (CBH<2000 m), middle (2000?CBH<5000 m), and high (CBH?5000 m). In the results, CRC is almost proportional and inverse proportional to cloud cover (CC) and CBH in the average, respectively. However, CRC for low cloud shows proportion to CBH because existence of low altitude cloud is related to large precipitable water (PW).

Yamada, Kyohei; Hayasaka, Tadahiro; Sugimoto, Nobuo

2012-11-01

11

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

12

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

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

13

The coupling of cloud base height and surface fluxes: a transferability intercomparison  

NASA Astrophysics Data System (ADS)

This paper presents an evaluation of the simulated coupling between cloud base height (CBH) and surface fluxes over selected Coordinated Enhanced Observing Period (CEOP) reference stations by five regional climate models as part of a transferability intercomparison experiment. The model results are compared with station data obtained during the first phase of the CEOP measuring campaigns. The models gave a credible simulation of both diurnal and seasonal cycles of cloud base height and surface variables over the stations. However, the models exhibited some difficulty in reproducing the diurnal and seasonal temperatures over the tropical stations. The study used principal component analysis to show that three factors account for most of the variability in the observed and simulated data and to investigate the coupling between cloud base height and surface fluxes in the data. In the observations, CBH is well coupled with the surface fluxes over Cabauw, Bondville, Lamont, and Berms, but coupled only with temperature over Lindenberg and Tongyu. All models but GEMLAM simulate substantial coupling between CBH and surface fluxes at all stations; GEMLAM does not couple CBH with surface fluxes, but with surface temperature and specific humidity.

Gbobaniyi, Emiola O.; Abiodun, Babatunde J.; Tadross, Mark A.; Hewitson, Bruce C.; Gutowski, William J.

2011-11-01

14

Multifractal characterization of nonstationarity and intermittency of cloud base height signals  

NASA Astrophysics Data System (ADS)

Cloud base profiles measured with laser ceilometer are studied using multifractal approach. The method assesses nonstationarity and intermittency pertinent to such highly fluctuating signals. The irregular structure of the signals is a benchmark for non-linear dynamics processes. The analysis searches for the scaling properties of q-th order singular measures and q-th order structure functions. Therefore, the method seeks for various scales of self-affinity, i.e. searches for multi-affinity. We found that multifractality is the signature of the cloud base height profiles, characterized with a hierarchy of exponents q H(q) and K(q). The value of the roughness parameter H1 is consistent with the one obtained for the same data using different method of analysis. The multifractal behavior is consistent also with the multi- affine properties of other atmospheric data recorded simultaneously during the same field experiment ASTEX'92.

Gospodinova, Nadia S.; Ivanova, K.; Clothiaux, Eugene E.; Ackerman, Thomas P.

2001-04-01

15

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

16

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

17

Neural network sensor fusion: Creation of a virtual sensor for cloud-base height estimation  

NASA Astrophysics Data System (ADS)

Sensor fusion has become a significant area of signal processing research that draws on a variety of tools. Its goals are many, however in this thesis, the creation of a virtual sensor is paramount. In particular, neural networks are used to simulate the output of a LIDAR (LASER. RADAR) that measures cloud-base height. Eye-safe LIDAR is more accurate than the standard tool that would be used for such measurement; the ceilometer. The desire is to make cloud-base height information available at a network of ground-based meteorological stations without actually installing LIDAR sensors. To accomplish this, fifty-seven sensors ranging from multispectral satellite information to standard atmospheric measurements such as temperature and humidity, are fused in what can only be termed as a very complex, nonlinear environment. The result is an accurate prediction of cloud-base height. Thus, a virtual sensor is created. A total of four different learning algorithms were studied; two global and two local. In each case, the very best state-of-the-art learning algorithms have been selected. Local methods investigated are the regularized radial basis function network, and the support vector machine. Global methods include the standard backpropagation with momentum trained multilayer perceptron (used as a benchmark) and the multilayer perceptron trained via the Kalman filter algorithm. While accuracy is the primary concern, computational considerations potentially limit the application of several of the above techniques. Thus, in all cases care was taken to minimize computational cost. For example in the case of the support vector machine, a method of partitioning the problem in order to reduce memory requirements and make the optimization over a large data set feasible was employed and in the Kalman algorithm case, node-decoupling was used to dramatically reduce the number of operations required. Overall, the methods produced somewhat equivalent mean squared errors indicating that the descriptive capacity of the data had been reached. However, the support vector machine was the clear winner in terms of computational complexity. As well, through its ability to determine its own dimensionality it is able to relate information about the physics of the problem back to the user. This thesis, contributes to the literature on three fronts. First, it demonstrates the concept of creating of a virtual sensor via sensor fusion. Second, in the remote-sensing field where focus has typically been on pattern classification tasks, this thesis provides an in-depth look at the use of neural networks for tough regression problems. And lastly, it provides a useful tool for the meteorological community in creating the ability to add large-scale, cloud-field information to predictive models.

Pasika, Hugh Joseph Christopher

2000-10-01

18

Feasibility study of cloud base height remote sensing by ground-based sky thermal infrared brightness temperature measurements  

Microsoft Academic Search

Infrared remote sensing of clouds is one of the main subjects in the field of atmospheric remote sensing from satellites. As its characteristics of intense infrared radiation and absorption the heights of cloud top can generally be derived from the brightness temperature obtained from satellite infrared cloud images and then a series of study about cloud morphologic microphysics and dynamics

Wenxing Zhang; Daren Lu; Youli Chang

2005-01-01

19

A new method for retrieving equivalent cloud base height and equivalent emissivity by using ground-based high-resolution infrared radiance  

NASA Astrophysics Data System (ADS)

Based on the ground-based high-resolution infrared radiances observed by the Atmospheric Emitted Radiance Interferometer (AERI), a new method is proposed to identify the clear sky. Meanwhile, we also develop the new algorithms for retrieving the zenith equivalent cloud base height (CBHe) and the equivalent emissivity (?e), respectively. The retrieval results in Shouxian indicate that the differences between the CBHe and observational cloud base height (CBH) are much smaller for thick low cloud, and increase with the increasing CBH. The average ?e for the low, middle, and high cloud is 0.967, 0.781, and 0.616 for the 50 cases, respectively. It decreases with the increasing CBH. The new methods will be useful for studying the role of cloud in the radiation budget in the window region and cloud parameterizations in the climate model.

Pan, LinJun; Lu, DaRen

2013-05-01

20

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

21

Comparison between ATSR-2 stereo, MOS O2-A band and ground-based cloud top heights  

Microsoft Academic Search

A new method to retrieve cloud top heights stereoscopically using the dual?view facility of the Along Track Scanning Radiometer 2 (ATSR?2) instrument is assessed. This assessment is performed through a comparison of the cloud top heights obtained from ATSR?2 stereo and those derived from a 94?GHz radar, radiosonde profiles and independently from the Modular Optoelectronic Scanner (MOS) using the O2?A

C. Naud; K. L. Mitchell; E. E. Clothiaux; P. Albert; R. Preusker; J. Fischer; R. J. Hogan

2007-01-01

22

Lidar validation of VAS cirrus cloud height determinations  

NASA Technical Reports Server (NTRS)

The determination of cirrus cloud pressure altitude and IR attenuation using CO2 channel radiometric data from the VISSR (Visible and Infrared Spin Scan Radiometer) Atmospheric Sounder (VAS) on board the GOES geostationary satellite is discussed. The independent ground-based determination of cirrus cloud altitude, thickness, and optical properties obtained with the High Spectral Resolution Lidar (HSRL) is described. HSRL cirrus cloud measurements are compared to VAS CO2 cloud top height retrievals generated for the First International Satellite Cloud Climatology Project Regional Experiment cirrus intensive Field Observations, held in Wisconsin in October and November of 1986.

Grund, Christian J.; Eloranta, Edwin W.; Wylie, Donald P.

1989-01-01

23

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

24

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 ...

Ivanova, Dorothea

25

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

26

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

27

Retrieval of cloud height from SCIAMACHY using oxygen absorption around 630nm  

NASA Astrophysics Data System (ADS)

The SCanning Imaging Absorption spectrometer for Atmospheric ChartographY (SCIAMACHY) on ENVISAT allows measurements of different atmospheric trace gases (e.g. O3, NO2, SO2, CH4, HCHO, CO, BrO, H2O, O2, O4) using the DOAS technique. The HICRU algorithm retrieves cloud height using the spectral analysis of the oxygen absorption around 630nm combined with results of the Monte-Carlo model TRACY-II and a new SCIAMACHY surface albedo database. The results are compared to: 1.) cloud height retrievals of other satellite instruments (MERIS, MODIS) 2.) ISCCP climatology 3.) SCIAMACHY cloud algorithms (SACURA, FRESCO+) 4.) LIDAR/RADAR measurements. For low clouds, the HICRU algorithm retrieves cloud heights more close to the the top, because of the assumption of an appropriate cloud model with a realistic estimation of the scattering inside the cloud. It is also demonstrated, that none the three SCIAMACHY cloud algorithms HICRU, SACURA and FRESCO+ is able to retrieve the top of high clouds because of principal characteristics of the retrieval methods based on oxygen absorption. But oxygen absorptions can provide important additional information on the vertical cloud structure and multiple cloud layers if the method is combined with cloud-top-retrieval using windows in the thermal infrared. An application of these concepts to the GOSAT instrument will be discussed.

Grzegorski, Michael; Deutschmann, Tim; Platt, Ulrich; Wang, Ping; Wagner, Thomas

2010-05-01

28

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

Microsoft Academic Search

A simple and fast algorithm for generating two correlated stochastic two-dimensional (2D) cloud fields is described. The algorithm is illustrated with two broken cumulus cloud fields: cloud optical depth and cloud-top height retrieved from the Moderate Resolution Imaging Spectroradiometer (MODIS). Only two 2D fields are required as an input. The algorithm output is statistical realizations of these two fields with

Sergei M. Prigarin; Alexander Marshak

2009-01-01

29

Cloud Height Maps for Hurricanes Frances and Ivan  

NASA Technical Reports Server (NTRS)

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

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

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

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

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

2004-01-01

30

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

31

6.G Base and Height  

NSDL National Science Digital Library

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

32

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

33

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

34

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

E-print Network

the Arica Bight at ;208S. Diurnal cloud-top height variations (inferred from irregular 4-times and west in the afternoon. Cloud-top heights above the Arica Bight region are depressed in the afternoon into the western equatorial Pacific (e.g., Richter and Mechoso 2006; Takahashi and Battisti 2007; Xu et al. 2004

Zuidema, Paquita

35

Comparison of SAGE-II and HIRS co-located cloud height measurements  

NASA Astrophysics Data System (ADS)

The CO2 Slicing analysis of HIRS satellite data for cloud heights at the University of Wisconsin (Wylie and Menzel, 1999) is known to report cloud heights that are below the upper boundary (i.e., the geometric top) of the clouds for semi-transparent cirrus. The reason for the discrepancy between the geometric cloud top and the cloud height derived from the CO2 Slicing analysis is well understood from radiative transfer calculations. It occurs because the CO2 Slicing analysis uses satellite measurements of infrared absorption and emission in clouds. For clouds semi-transparent to terrestrial radiation, absorption and emission occur throughout the cloud so that the CO2 Slicing analysis reports a height indicative of where the absorption and emission occurred inside the cloud. However, some applications need data on the geometric cloud top and need to know the bias of the CO2 Slicing analysis from the geometric top. To statistically evaluate this bias, cloud height data derived from the CO2 Slicing analysis were compared to a more sensitive measurement of the geometric cloud top from the SAGE-II satellite sensor. This study employed 71 clouds where both the HIRS and SAGE-II sensors made height measurements at nearly the same time. The comparison found that the Wisconsin CO2 Slicing analysis underestimated the geometric cloud top by an average of 1.6 km. This bias increased slightly to 2.0 km for upper troposphere clouds. This is close to the previous studies of the CO2 Slicing analysis.

Wylie, Donald P.; Wang, Pi-Huan

36

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

37

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

E-print Network

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

Sheridan, Jennifer

38

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

39

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.

40

Estimation of cirrus and stratus cloud height using landsat data and 3D graphical representation  

NASA Astrophysics Data System (ADS)

Cirrus and stratus cloud heights are estimated using LANDSAT MSS(MultiSpectral Scanner) and TM(Thematic mapper) data. Cloud heights are calculated from the sun elevation angle and the horizontal distance between cloud and its shadow templates. The matching of these templates is accomplished by the 2D cross-correlation function. Before accomplishing the matching, histogram equalization, inversion of shadow template, and Fourier Fast Transformation are applied to both templates. Then 2D cross-correlation function is calculated in the frequency domain. Correlation coefficients are 3D graphically displayed to check visually how sharply the templates match. The effects of the skew angle and the nonnadir observation angle are taken into consideration to modify the direction from the cloud template to its corresponding shadow template. The results show that this method is accurate within several pixels.

Inomata, Y.; Takagi, K.; Shiiba, T.; Akitake, R.

41

Comparison of cloud top heights derived from MISR stereo and MODIS CO2slicing  

Microsoft Academic Search

The EOS-TERRA MODIS and MISR instruments provide radiances for independent spectral and stereo retrievals of cloud top height (CTH), respectively. Collocated and coincident CTH retrievals were compared against each other and with coincident millimeter-wavelength cloud radar (MMCR) retrievals over the British Isles and the ARM SGP site. This inter-comparison suggests close agreement between MMCR, MODIS and MISR when they detect

Catherine Naud; Jan-Peter Muller; Eugene E. Clothiaux

2002-01-01

42

AUGUST 2002 885N O T E S A N D C O R R E S P O N D E N C E Comparison between Observed Convective Cloud-Base Heights and Lifting  

E-print Network

or LCL table/diagram such as the convective cloud-base diagram in OFCM (1982) (Fig. 1). Stull several ways, including at any single level in the vertical (usually in the lowest 300 hPa), or using is not along a mixing-ratio line through the entire boundary layer, as would be expected). Strong

43

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

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

44

Comparison of cloud top heights derived from MISR stereo and MODIS CO 2 slicing  

Microsoft Academic Search

The EOS-TERRA MODIS and MISR instruments provide radiances for independent spectral and stereo retrievals of cloud top height (CTH), respectively. Collocated and coincident CTH retrievals were compared against each other and with coincident millimeter-wave radar (MMCR) retrievals over the British Isles and the ARM SGP site. This inter- comparison suggests close agreement between MMCRR, MODIS and MISR when they detect

Catherine Naud; Jan-Peter Muller; Eugene E. Clothiaux

45

Multi-Sensor Analysis of Cloud-Top Height in Sc - Cu Transition Regions  

NASA Astrophysics Data System (ADS)

In the eastern basins of the subtropical oceans unbroken sheets of stratocumulus transition to fields of scattered cumulus as boundary-layer air masses advect equatorward in the trades. This shift in cloud regimes is the subject of intense modeling efforts, because it has profound effects on the local and the planetary albedo. To provide observational constraints for such modeling studies, we analyzed satellite measurements of boundary-layer cloud-top heights (CTHs) in the northeast and southeast Atlantic and Pacific. Our sensor suite comprised CALIPSO-CALIOP, MODIS, MISR, and Meteosat-9. The study covered the summer months June-August and September-November for the northern and southern hemisphere, respectively, spanning the period 2006-2009. We considered CALIOP lidar measurements the most accurate and, hence, used them as reference. The operational Collection 5 MODIS CTHs were based on fitting measured cloud-top temperatures (CTTs) to forecast temperature profiles and were known to have large biases in case of low-level inversions. Therefore, we also evaluated CTHs derived from CTT-SST differences and various lapse rate formulations, which is the method suggested for the upcoming Collection 6 dataset. The MISR stereo CTHs were computed from a purely geometric method, which, however, is rather sensitive to errors in along-track wind speed. Because our previous work indicated a MISR cross-swath speed bias, we created a modified CTH dataset by replacing MISR winds with Meteosat-9 winds to correct the raw MISR stereo heights. The various satellite retrievals were then compared over whole regions as well as along characteristic Sc-Cu transition trajectories computed with the HYSPLIT model. For context, results from LES transition simulations were also analyzed. Some highlights of our study are summarized below. The CALIOP, MISR, and lapse-rate-based MODIS CTHs all showed a systematic increase of 500-700 m in the southeast Atlantic and northeast Pacific as Sc transitioned to Cu. In the northeast Atlantic and southeast Pacific, however, these CTHs had no obvious trends and remained fairly constant. Operational MODIS CTHs indicated an erroneously decreasing trend along transition trajectories in all four regions due to large (500-1500 m) overestimations in the Sc regime (although they were fairly reasonable in the Cu regime). The best MODIS dataset was a hybrid one combining current operational retrievals and lapse-rate-based heights depending on the presence or lack of low-level inversions. Overall, MISR CTHs compared most favorably to CALIOP with typical correlations and biases of 0.7 and 150 m, respectively. In the southeast Atlantic, MISR CTH errors could be further reduced by 15-30% when using Meteosat-9 winds for height correction, thereby removing apparent cross-swath biases.

Ludewig, E.; Horvath, A.

2010-12-01

46

Cloud Condensation Nuclei Retrievals at Cloud Base in North Dakota  

E-print Network

accuracy #12;POLCAST4 Polarimetric Cloud Analysis and Seeding Test 4 Field campaign held in the summerCloud Condensation Nuclei Retrievals at Cloud Base in North Dakota · Mariusz Starzec #12;Motivation Compare University of Wyoming (UWyo) and Droplet Measurement Technologies (DMT) cloud condensation nuclei

Delene, David J.

47

Ground-Based Lidar and Radar Remote Sensing of Tropical Cirrus Clouds at Nauru Island: Cloud Statistics and Radiative Impacts  

SciTech Connect

Ground based active and passive remote sensing instrumentation are combined to derive radiative and macrophysical properties of tropical cirrus clouds. Eight months of cirrus observations at the Department of Energy Atmospheric Radiation Measurement site located on Nauru Island provide independent retrieval of cloud height and visible optical depth using lidar and radar techniques. Comparisons reveal the millimeter cloud radar does not detect 13% of cirrus clouds with a cloud base higher than 15 km that are detected by the lidar. Lidar and radar cloud heights demonstrate good agreement when the cloud lies below 15 km. Radar and lidar retrievals of visible optical depth also compare well for all but the optically thinnest clouds. Cloud occurrence at Nauru as measured by lidar, reveal clear sky conditions occur on average 40%, low clouds 16%, and high clouds 44% of the time. Analysis of observed cirrus macrophysical and radiative properties suggests that two different types of cirrus exist in the tropical western Pacific: high, thin, laminar cirrus with cloud base higher than 15 km, and lower, physically thicker, more structured cirrus clouds. Differences in cirrus types are likely linked to their formation mechanisms. Radiosonde profiles of temperature and equivalent potential temperature near the tropical tropopause show a clear transition between neutrally stable and stable air at ~15 km, which may also explain the presence of two distinct cirrus types. Radiative heating rate and cloud forcing calculations for specific cirrus cases reveal the impact of tropical cirrus clouds on the earth?s radiation budget.

Comstock, Jennifer M.; Ackerman, Thomas P.; Mace, Gerald G.

2002-12-12

48

Rise of Volcanic Eruption Clouds: Relationship between Cloud Height and Eruption Intensity.  

National Technical Information Service (NTIS)

The rise of eruption clouds is produced by the upward momentum and thermal buoyancy of volcanic dust and gas, processes which play important roles in other phenomena. The expansion of a turbulent jet in free flow is controlled by the rate at which the for...

M. Settle

1976-01-01

49

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

50

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

51

Projection of changes in tropical cyclone activity and cloud height due to greenhouse warming: Global cloud-system-resolving approach  

NASA Astrophysics Data System (ADS)

Tropical cyclone (TC) activity change due to global warming (GW) has been investigated using general circulation models. However, they involve uncertainty in treating the ensemble effects of deep convections. Here we sidestep such uncertainty by using a global cloud-system-resolving model (GCRM) and assess TC changes with a time-slice experiment for the present-day and future GW experiments spanning 5 months each. The results support the Intergovernmental Panel on Climate Change Fourth Assessment Report; reduction in global frequency but increase in more intense TCs. Consistent with recent studies, frequency is reduced over the North Atlantic due to intensified vertical wind shear. Over the Pacific, frequency is almost unchanged and the genesis location shifts eastward under the prescribed El-Niño like sea surface temperature change. With the GCRM's advantage of representing mesoscale properties, we find that the cloud height becomes taller for more intense TCs and that this relationship is strengthened with GW.

Yamada, Yohei; Oouchi, Kazuyoshi; Satoh, Masaki; Tomita, Hirofumi; Yanase, Wataru

2010-04-01

52

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

53

Past, present, and future of the MISR height-resolved, cloud-track wind retrieval  

NASA Astrophysics Data System (ADS)

MISR multi-angle measurements offer the unique capability of resolving position, altitude, and motion of clouds over a 7 minute interval, purely by image correspondence and geometric triangulation. Cloud motion is retrieved operationally at 70.4km x 70.4km horizontal resolution and packaged as part of the MISR standard suite of products. A consistent approach, requiring no a priori information and applied globally throughout MISR’s 10-year history, make this product suitable for reanalysis of wind in observation sparse regions such as the Poles or the Southern Ocean. Featuring far superior resolution (17.6km along satellite trajectory, 1.1km across), 2.5 times the coverage, and increased precision and accuracy, the upcoming MISR cloud motion product will extend scientific applicability to the mesoscale: including hurricane modeling, and marine stratocumulus organization. This product release will build upon a steady evolution of algorithm enhancements that have transformed cloud motion retrieval from a measurement first conceived as a means of calculating unbiased cloud height, into a first-class science product. Here we will review previous and upcoming milestones in this evolution. The accuracy, bias, and coverage of past and forthcoming algorithm revisions relative to standard wind validation datasets including rawinsonde retrievals and NCEP reanalysis will be reviewed.

Mueller, K. J.; Moroney, C. M.; Garay, M. J.; Jovanovic, V. M.

2009-12-01

54

Analysis of tropical cloud systems using a new cloud-top height data by geostationary satellite split-window measurements trained with CloudSat data  

NASA Astrophysics Data System (ADS)

Lookup tables for estimating the cloud-top height (CTOP) and visible optical thickness of upper-tropospheric clouds by the infrared brightness temperature (TB) at 10.8 ?m (T11) and its difference from TB at 12 ?m (DT11-12) measured by geostationary satellites are developed (Hamada and Nishi 2010, JAMC). These lookup tables were constructed by regressing the cloud radar measurements by the CloudSat satellite over the infrared measurements by the Japanese geostationary multifunctional transport satellite MTSAT-1R and MTSAT-2. The calculated CTOP is available at http://database.rish.kyoto-u.ac.jp/arch/ctop/ since July 2005. A merit of this dataset is that standard deviations of measurements around the estimates were also available as an indicator of the ambiguity in the estimates. The data have good precision for tropical cirrus clouds that have large DT11-12 values and suitable for analyses of cloud systems with well-developed cirrus clouds. We made correction for the satellite view angle and can offer the data over almost all tropical regions where the satellites can observe (20S-20N, 80E-160W for MTSAT-1R and 85E-155W for MTSAT-2). We analyzed zonally elongated cloud band extending 3000 km around ITCZ. It was first tightly concentrated at the ITCZ latitude and then spread meridionally into the two parallel zonal cloud bands. They kept moving meridionally away even after the cumulonimbi that could make divergence wind were hardly seen around the ITCZ. This phenomenon attracted attention during January 1993, the intensive observation period (IOP) of the Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE). Since there were not enough rainfall and cloud height information at that time, it was not clear why meridional separation starts simultaneously in the wide zonal region and what causes the continuous meridional separation over a day. In this study, we detected some typical cases in 2007, covered with our CTOP data. We examined detail of the separation with our CTOP data and Global Satellite Mapping of Precipitation (GSMaP; Kubota et al. 2007, IEEE Trans. Geosci. Remote Sens) data: precipitation estimation dataset made with microwave radiometers including Tropical Rainfall Measuring Mission/Microwave Imager (TRMM/TMI). We found that the separated cloud bands had little precipitation regions (larger than 1mm/hour) and CTOP was above 12 km. The facts show that the bands consist of the cirriform clouds passively advected by larger-scale wind. However, there are little active cumulus systems, which generally create horizontal divergence in the cirrus height, between and within the cloud bands, when examining GSMaP data and optical thickness estimation in the CTOP data. Though we do not have conclusive idea for this separation mechanism, one plausible candidate is a westward-moving equatorial trapped inertial gravity wave. It was observed around these cloud bands and can make meridional divergence without cumulus activity.

Nishi, N.; Hamada, A.; Ohigawa, M.; Shige, S.

2011-12-01

55

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 deseasonalised 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 vapor.

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

2013-12-01

56

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

57

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

58

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

59

On the use of ICESAT-GLAS measurements for MODIS and SEVIRI cloud-top height accuracy assessment  

Microsoft Academic Search

This study reports on the first attempt to use cloud boundary and optical depth retrievals from the GLAS lidar to assess the accuracy of cloud-top heights obtained with MODIS (onboard NASA-TERRA and AQUA) and SEVIRI (onboard METEOSAT-8). Over the period from 25 September to 18 November 2003, MODIS-GLAS coincidences were only found in the Polar Regions, whilst SEVIRI-GLAS coincidences were

Catherine Naud; Jan-Peter Muller; Paul de Valk

2005-01-01

60

Aircraft Microphysical Documentation from Cloud Base to Anvils of Hailstorm Feeder Clouds in Argentina  

E-print Network

in research to increase understanding of hail- producing clouds and their response to seeding inter- ventionAircraft Microphysical Documentation from Cloud Base to Anvils of Hailstorm Feeder Clouds, Argentina, with a cloud-physics jet aircraft penetrating the major feeder clouds from cloud base to the 45°C

Daniel, Rosenfeld

61

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

62

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.

63

Height estimations based on eye measurements throughout a gait cycle.  

PubMed

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

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

2014-03-01

64

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

65

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

Microsoft Academic Search

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

Peter S. Masika

66

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

E-print Network

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

Melbourne, University of

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

Measurements of Cloud Characteristics with a Ceilometer and Supporting Measurements with a Water Based Condensation Particle Counter  

NASA Astrophysics Data System (ADS)

A Vaisala Laser Ceilometer which employs the LIDAR technique with a 910 nm laser diode for measurement of cloud base height, sky condition and vertical visibility was set up at a tropical coastal station Thiruvananthapuram (8.29° N, 76.59° E)at Kerala state, India. Measurements of cloud base height during different rain spells were made to understand the basic nature of cloud during different types of rain episodes such as convective and stratiform rains. Information on diurnal variation of cloud base height for different seasons has been obtained. The dominant altitude range of cloud occurrence is found to be below 1.5 km for clouds of all rainy seasons. The southwest monsoon clouds were dominant below 500 m also. The Ceilometer with its data on visibility also gave a picture of particles that can scatter the laser which includes water in liquid and ice phases. During dry weather conditions visibility below 1 km was found to be relatively low. To understand the cause of visibility change, a water based condensation nuclei counter manufactured by M/s TSI Inc, USA was employed and concentration monitored. An attempt was also made to get the cloud base height characteristics on a mountain slope to understand the orographic lifting of clouds due to mountain slope during different rainy seasons. At the mountain location data on cloud base measurements during cloud formation by orographic lifting of water vapour during thunderstorm months of the region is also presented and discussed.

Vishnu, R.; Muralidas, S.; Mohankumar, G.; Varikoden, Hamza; v, Sasi Kumar; Sampath, S.; Vishnu, R.

69

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

70

An Assessment of Factors Limiting Tropical Congestus Cloud-Top Heights  

E-print Network

Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations CDF Cumulative Density Function CFAD Contoured Frequency by Altitude Diagram CPR Cloud Profiling Radar DJF December-January-February ECMWF European Centre for Medium-Range Weather... ?congestus? line) and transient congestus (marked as the dashed ?deep? line), as defined by Luo et al. [2009] ............................................. 22 10 Contoured Frequency by Altitude Diagram (CFAD) of the differences between RH observations...

Casey, Sean P.

2010-07-14

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

Satellite-observed cloud-top height changes in tornadic thunderstorms  

NASA Technical Reports Server (NTRS)

Eleven tornadic storms are evaluated with respect to cloud top temperature changes relative to tornado touchdown. Digital IR data from the SMS/GOES geosynchronous satellites were employed for 10 F2 and one F1 tornadoes. A rapid ascent of the cloud tops 30-45 min before tornado touchdown, a temperature decrease of 0.4 K/min, and an ascent rate of about 3 m/sec were observed. The presence of an operating Doppler radar for three of the sample storms allowed detection of a mesocyclone coincident with the rapid cloud top ascent. The intensification and descent of the vortex to form a tornado is concluded to be due to a weakening of the updraft, the formation of a downdraft, and a shift of the vortex to the updraft-downdraft boundary, leading to dominance of the tilting term in the generation of vorticity.

Adler, R. F.; Fenn, D. D.

1981-01-01

73

Design of an Accounting and Metric-based Cloud-shifting and Cloud-seeding framework for Federated  

E-print Network

Design of an Accounting and Metric-based Cloud-shifting and Cloud-seeding framework for Federated Clouds, Cloud seeding, Cloud shifting. 1. INTRODUCTION Batch, Cloud and Grid computing build the pillars Clouds and Bare-metal Environments Gregor von Laszewski1 *, Hyungro Lee1 , Javier Diaz1 , Fugang Wang1

74

Clouds  

NSDL National Science Digital Library

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

75

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

76

Improving lidar-based mixing height measurements with radon-222  

NASA Astrophysics Data System (ADS)

We have found that near-surface hourly atmospheric radon-222 measurements can be combined with elastic backscatter lidar data to obtain a higher quality time-series of mixing height than is currently possible with lidar data alone. The standard method of determining mixing heights from lidar observations relies on algorithms which detect the contrast between relatively turbid aerosol-laden air within the boundary layer and clear air above. However, this approach can be confounded by meteorological conditions that lead to the formation of multiple aerosol layers within or above the boundary layer, or when the contrast between boundary layer air and the overlying air is weak. In such ambiguous circumstances, extra information would be helpful to choose the appropriate mixing height. Radon-222 has the properties-almost-of an ideal passive tracer emitted at a constant rate from the surface. Assuming horizontal homogeneity, the near-surface concentration time-series can be inverted to determine an effective mixing height, which is equal to the true mixing height if the tracer is mixed uniformly throughout the boundary layer. A time-series of effective mixing heights derived in this manner can then be used to choose between lidar-derived candidates for mixing height in ambiguous meteorological conditions. This approach has the potential to extend the usefulness of lidar observations to conditions where, at present, it is only marginally applicable, and to improve the performance of automatic PBL height detection procedures. A time-series of mixing heights derived from a combination of lidar and radon observations would have fewer gaps, and therefore be more useful for applications such as model validation or pollution studies under a wider range of meteorological conditions.

Griffiths, A.; Chambers, S.; Parkes, S.; Williams, A. G.; McCabe, M.

2012-04-01

77

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.

78

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

NASA Astrophysics Data System (ADS)

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

Jewett, Christopher P.; Mecikalski, John R.

2013-11-01

79

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

80

Variations in Forest Canopy Height structure across the Amazon Basin, Brazil based on GLAS LiDAR  

NASA Astrophysics Data System (ADS)

LiDAR remote sensing has proven to be a valuable source of information for remote characterization of vegetation structure. The data coverage provided by GLAS, over 14 million returns throughout the Brazilian Amazon basin provides a unique opportunity to further understanding of canopy structure. Previous research at Tapajós National Forest, in the state of Pará, Brazil, has shown an increasing trend in canopy height based on distance from water (Hunter, et al. 2007). This trend may be due to a combination of factors such as soil type, forest history and disturbance pattern. This work tests this relationship throughout the Brazilian Amazon, and compares results with regional flooding regimes. Using a type cover map based upon PRODES 2006, with clouded regions filled in where possible using PRODES 2005, forest and water coverages were separated from other cover types. Over a million GLAS waveforms are available within forest cover types within 3 kilometers of water. Distributions of canopy height estimates (Lefsky, ICESat Vegetation Product, heights ver 0.3) were used to calculate variation of canopy height with distance from water. The Brazilian Amazon was divided into regions of 2 x 2 degrees. The change in 10th percentile height was positive for 84 of 91 regions tested, with a mean increase of approximately 3m. The strongest relationships were found along the main branch of the Amazon River.

Hunter, M.; Keller, M.; Braswell, R.; Lefsky, M.

2008-12-01

81

Model based building height retrieval from single SAR images  

Microsoft Academic Search

With the improvements of spaceborne and airborne SAR system resolution, the applications of radar remote sensing has been extended to building 3D geometric information retrieval and reconstruction from urban SAR images, which is the foundation of build-up areas reconstruction and urban analysis. This paper mainly focuses on the problem of building height estimation from a single high resolution (HR) SAR

Li-bing Jiang; Zhuang Wang; Wen-xian Yu

2011-01-01

82

Study on the user preferences based on cloud model  

Microsoft Academic Search

Point out the fuzziness and uncertainty of user preferences. Put forward the advantage of using cloud model to calculate the user preferences. Introduce the cloud model and construct the model of user preferences based on cloud model. Design one new algorithm for calculating the user preferences with time weight. The experiments show the personalized recommend based on the new user

Rong Luo; Qingjun Xue

2009-01-01

83

Essentials for CSPs to Succeed with Cloud-based Services  

E-print Network

WITH CLOUD-BASED SERVICES INTRODUCTION For many, cloud-based services represent a new way to do the same old, cloud services are a means for providing essentially the same old user experience but at a better price. Can such a point of view really have merit? Stratecast believes there is an inherent problem

84

Cloud-Based Mobile Computing Applications Platform for First Responders.  

National Technical Information Service (NTIS)

A cloud-based Mobile Computing Applications Platform (MCAP) for enhanced situational awareness and mobile command and control for first responders is introduced. MCAP is a cloud-enabled platform for defining, developing, and deploying apps on smartphones,...

C. Chung, C. Misner, D. Egan, N. Caruso, R. Wallace

2013-01-01

85

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

86

Cloud field classification based on textural features  

NASA Technical Reports Server (NTRS)

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

Sengupta, Sailes Kumar

1989-01-01

87

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

E-print Network

of Atmospheric Sciences, University of North Dakota 2012 Polarimetric Cloud Analysis and Seeding Test 4 (POLCAST4Cloud 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

Delene, David J.

88

A client-based privacy manager for cloud computing  

Microsoft Academic Search

A significant barrier to the adoption of cloud services is that users fear data leakage and loss of privacy if their sensitive data is processed in the cloud. In this paper, we describe a client-based privacy manager that helps reduce this risk, and that provides additional privacy-related benefits. We assess its usage within a variety of cloud computing scenarios. We

Miranda Mowbray; Siani Pearson

2009-01-01

89

Process-based Management of Cloud Computing Infrastructure  

E-print Network

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

Krause, Rolf

90

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

SciTech Connect

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

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

2010-05-27

91

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

92

Combined remote sensing of cloud characteristics with surface-based radar, lidar, and all sky imagers over Beijing, China  

NASA Astrophysics Data System (ADS)

Clouds have been known as the key components of atmospheric processes in climate, weather, and environment related issues. Owing to its highly complicated processes relating to atmospheric dynamic, macro and microphysical characteristics reveal distinct regional and seasonal features, thus observations at various typical sites are very important to quantitatively understand cloud characteristics with their functions. In this paper, we introduce combined ground-based instruments, i.e., a Mie Lidar, a Ka-band Doppler radar, an IR and a visible all sky imagers, and an automatic weather station, to continuously observe the clouds over Beijing. Synthetic analyses are made to derive the cloud base height, vertical structure, horizontal distribution, radiative effect, etc. About 1 year observation data are used to obtain the statistics of cloud characteristics in this area. A simple introduction of the surface-based remote sensing system and some preliminary results are given.

Liu, Jinli; Lu, Daren; Bi, Yongheng; Duan, Shu; Yang, Yong; Pan, Yubin; Li, Yu

2013-05-01

93

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

94

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

E-print Network

Targeting and impacts of AgI cloud seeding based on rain chemical composition and cloud top phase seeding enhanced rainfall in Northern Israel. © 2012 Elsevier B.V. All rights reserved. Keywords: Cloud seeding Silver iodide (AgI) Rain chemistry Satellite images 1. Introduction Cloud seeding with AgI has

Daniel, Rosenfeld

95

Edge detection of images based on cloud model cellular automata  

Microsoft Academic Search

In order to resolve the problems of edge detection algorithm of images based on fuzzy seasoning or cellular automata, a new improved edge detection algorithm of images based on cloud model cellular automata is presented. This method uses direction information and edge order information as edge characteristic information, uses cloud model to inference these information, then gives accurate feedback information

Zhang Ke; Zhang Weihua; Yuan Jinsha

2008-01-01

96

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

97

Contented-Based Satellite Cloud Image Processing and Information Retrieval  

Microsoft Academic Search

Satellite cloud image is a kind of useful image which includes abundant information, for acquired this information, the image\\u000a processing and character extraction method adapt to satellite cloud image has to be used. Content-based satellite cloud image\\u000a processing and information retrieval (CBIPIR) is a very important problem in image processing and analysis field. The basic\\u000a character, like color, texture, edge

Yanling Hao; Wei Shangguan; Yi Zhu; Yanhong Tang

2007-01-01

98

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

Microsoft Academic Search

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

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

2000-01-01

99

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

SciTech Connect

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

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

2000-02-27

100

Microphysical and radiative properties of boundary layer stratiform clouds deduced from ground-based measurements  

Microsoft Academic Search

Two methods for retrieving the microphysical and radiative properties of marine and continental boundary layer stratiform clouds from ground-based measurements are implemented. The first method uses measurements of the cloud liquid water path and the cloud nadir radiance at 1 mum to infer the cloud optical depth, cloud droplet effective radius, and cloud droplet concentration. In the second method a

Xiquan Dong; Thomas P. Ackerman; Eugene E. Clothiaux; Peter Pilewskie; Yong Han

1997-01-01

101

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 SICK� LMS 291 LIght Detection And Ranging (LIDAR) unit was evaluated in static and dynamic mode

102

Image segmentation based on data field and cloud model  

Microsoft Academic Search

There are many uncertainties in image segmentation, which needs theories and methods with uncertainty to handle. This paper proposes a novel method of image segmentation based on data field and cloud model, which considers the spatial information of image through data field, and handles the uncertainty of image through cloud model. The proposed method inspired from cognitive physics considers each

Kun Qin; Leihai Ou; Tao Wu; Yi Du

2010-01-01

103

Identity-based distributed cloud storage encryption scheme  

Microsoft Academic Search

Realizing the transformation from the storage device to the storage service by the application software is the core of cloud storage which is the combination of the application software and the storage device. However, the single cryptogram system cannot satisfy with the requirement of the privacy-preserving in cloud computing. Based on the assumption that the communication is absolute safe, an

Bao Zhang; Changgen Peng; Zhipin Xu

2011-01-01

104

Clouds  

NSDL National Science Digital Library

This lesson combines science, English and art to teach the students information about clouds and to encourage abstract thinking through writing and painting. Students will first read and discuss the information about clouds. Next, they will choose a type of cloud and write a composition about it. Then they do a painting of their cloud and attach their composition.

1998-01-01

105

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

2012-06-07

106

Cloud detection and classification based on MAX-DOAS observations  

NASA Astrophysics Data System (ADS)

Multi-axis differential optical absorption spectroscopy (MAX-DOAS) observations of aerosols and trace gases can be strongly influenced by clouds. Thus, it is important to identify clouds and characterise their properties. In this study we investigate the effects of clouds on several quantities which can be derived from MAX-DOAS observations, like radiance, the colour index (radiance ratio at two selected wavelengths), the absorption of the oxygen dimer O4 and the fraction of inelastically scattered light (Ring effect). To identify clouds, these quantities can be either compared to their corresponding clear-sky reference values, or their dependencies on time or viewing direction can be analysed. From the investigation of the temporal variability the influence of clouds can be identified even for individual measurements. Based on our investigations we developed a cloud classification scheme, which can be applied in a flexible way to MAX-DOAS or zenith DOAS observations: in its simplest version, zenith observations of the colour index are used to identify the presence of clouds (or high aerosol load). In more sophisticated versions, other quantities and viewing directions are also considered, which allows subclassifications like, e.g., thin or thick clouds, or fog. We applied our cloud classification scheme to MAX-DOAS observations during the Cabauw intercomparison campaign of Nitrogen Dioxide measuring instruments (CINDI) campaign in the Netherlands in summer 2009 and found very good agreement with sky images taken from the ground and backscatter profiles from a lidar.

Wagner, T.; Apituley, A.; Beirle, S.; Dörner, S.; Friess, U.; Remmers, J.; Shaiganfar, R.

2014-05-01

107

Summer cloud and precipitation properties at Utsteinen, Dronning Maud Land, Antarctica, measured by ground-based remote sensing instruments  

NASA Astrophysics Data System (ADS)

A unique comprehensive observatory on meteorological-cloud-precipitation interactions has been built at the new Belgian Princess Elisabeth station, situated on the Utsteinen ridge, at the foot of Sør Rondane mountains in East Antarctica (http://ees.kuleuven.be/hydrant). The instruments already installed include an automatic weather station (AWS) and three ground-based cloud and precipitation remote sensing instruments (ceilometer, infra-red pyrometer and 24GHz vertically pointing radar). The cloud and precipitation instruments have been operating during three summer periods (2009-2010, 2010-2011 and 2011-2012), while the AWS has been operating almost continuously since February 2009 through present time. The measurements are combined in order to obtain basic statistics of clouds properties (height and cloud base temperature), their radiative forcing, as well as frequency and vertical extension of snowfall events, together with the meteorological situation at Utsteinen. Measurements during the first two summer campaigns showed that cloud base temperatures ranged between -200C for low-level clouds (1-1.5 km agl) and -350C - -400C for midlevel clouds (2-4 km agl). The 1-3 km height range was found to have the highest cloud frequency. Synoptic events with and without snowfall have been related to the water vapor transport and local cloud properties. One of the analyzed storms with snowfall in February 2010 showed a two-day evolution with low-level and mid-level clouds observed during the first day, forming multiple layers with short periods of light precipitation, and lowering cloud bases during the second day followed by snowfall and blowing snow. Increase in the cloud base temperature associated both with warm air advection and cloud base lowering (to 1-1.5 km agl) before the snowfall resulted in significant increase in downwelling longwave flux (up to 20 W m-2) recorded by the AWS pyrgeometer. While ceilometer measurements are limited during the storm due to the signal attenuation by the falling and/or blowing snow, the radar measurements indicated that the depth of precipitating layer ranged from 1 km to at least 3 km agl (the limit of the radar vertical resolution). Analysis will be completed with the new data from the recent Antarctic summer season 2011-2012. With this new observatory, we aim at improving our understanding of the Antarctic hydrologic cycle and accumulation

Gorodetskaya, I. V.; van Lipzig, N. P. M.; Kneifel, S.; Maahn, M.; Crewell, S.; Van den Broeke, M.

2012-04-01

108

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

109

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

PubMed

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

Park, Sang Kyeong; Suh, Young Soo

2011-01-01

110

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

SciTech Connect

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

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

1994-12-20

111

Parameterizations of Cloud-Radiation Interactions Based on Detailed Cloud Microphysics  

NASA Astrophysics Data System (ADS)

Cloud-radiation effects still account for much of the variation among leading global climate models in sensitivity to greenhouse gases. A single-column model (SCM) allows results of different cloud-radiation parameterizations to be compared directly with measurements. The relevant fields include cloud altitude, cloud amount, liquid and ice content, particle size spectra, and radiative fluxes at the surface and the top of the atmosphere. Comparisons with data from the Atmospheric Radiation Measurement (ARM) Program show conclusively that prognostic cloud algorithms with detailed microphysics are far more realistic than simpler approaches. Long-term comparisons of SCM quantities strongly modulated by clouds, such as monthly mean downwelling surface shortwave radiation, clearly demonstrate the superiority of parameterizations based on comprehensive treatments of cloud microphysics and radiative interactions. The single-column model was run at the ARM Southern Great Plains, Tropical Western Pacific, and North Slope of Alaska sites using forcing data derived from operational numerical weather prediction models. Our results indicate that atmospheric radiative fluxes are sensitive to the scheme used to specify the ice particle effective radius by up to 30 W m-2 on a daily time scale and up to 5 W m-2 on a seasonal time scale. Differing treatments of ice particle fallout have a significant effect on the amount and location of high cirrus clouds. An unexpected finding was that the variance of the modeled ice particle effective radius at a given level is considerably smaller than that suggested by ARM cloud radar measurements. Our results indicate that this theoretical underestimate of the ice particle effective radius variance can have effects on modeled radiative fluxes comparable in magnitude to those cited above for sensitivity to the mean values of ice particle effective radius.

Iacobellis, S. F.; Somerville, R. C.; McFarquhar, G. M.; Mitchell, D.

2002-12-01

112

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

113

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

114

Describing the NPOESS Preparatory Project Visible/Infrared Imaging Radiometer Suite (VIIRS) Cloud Environmental Data Records  

NASA Astrophysics Data System (ADS)

The Visible/Infrared Imaging Radiometer Suite (VIIRS) is one of the instruments that make up the suite of sensors on the NPOESS Preparatory Project (NPP) scheduled to launch in 2010. VIIRS will produce seven Environmental Data Records (EDRs) describing cloud properties. The VIIRS Cloud EDRs include the Cloud Optical Thickness (COT), Cloud Effective Particle Size Parameter (CEPS), Cloud Top Pressure (CTP), Cloud Top Height (CTH), Cloud Top Temperature (CTT), Cloud Cover/Layers (CCL), and Cloud Base Height (CBH). This paper will describe the VIIRS algorithms used to generate these EDRs and provide a current estimate of performance based on pre-Launch test data.

Hoffman, C.; Guenther, B.; Kilcoyne, H.; Mineart, G.; St. Germain, K.; Reed, B.

2008-12-01

115

Towards a cloud-based integrity measurement service  

E-print Network

The aim of this paper is to propose the use of a cloud-based integrity management service coupled with a trustworthy client component – in the form of the Trust Extension Device (TED) platform – as a means to to increase ...

Zic, John

116

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

117

Ground Based Lidar Characterization of Cirrus Clouds  

NASA Technical Reports Server (NTRS)

This paper presents cirrus cloud observations made with the High Spectral Resolution Lidar (HSRL) and the Volume Imaging Lidar (VIL). The HSRL was redesigned to use an iodine absorption filter in place of the Fabry-Perot etalon that was used for spectral separation of the aerosol and molecular lidar returns. These modifications, which improve both sensitivity and calibration stability, are described.

Eloranta, Edwin W.

1996-01-01

118

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

119

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

E-print Network

- ever, before cloud-based EHR systems can become a reality, issues of data security, patient privacy General Terms Algorithms, Design, Security, Theory Keywords Cloud Computing, Electronic Health Records to improve healthcare qual- ity. Cloud computing has been viewed as an appropriate platform to deploy

Radziszowski, Stanislaw P.

120

Research on hadoop-based enterprise file cloud storage system  

Microsoft Academic Search

In order to solve the problem that enterprise-level users mass data storage and high-speed data processing services growth, and the traditional storage system can not meet the data services business growth, enterprise file cloud storage system is proposed. It is based on Hadoop, uses Linux cluster technology, distributed file systems and cloud computing framework, provides large-scale data storage and data

Da-Wei Zhang; Fu-Quan Sun; Xu Cheng; Chao Liu

2011-01-01

121

Cloud-based printing for mobile devices  

NASA Astrophysics Data System (ADS)

Consumers are increasingly using their smart phones to view web pages. However, there is no native operating system support for printing these web pages. We propose to overcome two barriers to printing from mobile devices - the inability to connect and transmit to a printer and the typically poor format of printed web pages. Our system includes a client component that causes the web browser to upload the page (as a URL reference for public pages or the DOM content for private pages) to a cloud service that extracts the content and formats it for printing. We transfer the printready content to the HP CloudPrint service and leverage its ability to locate printers and transmit print jobs. We have built a working system the uses iPhones and Windows Mobile devices clients, but the system can be extended to include other clients.

Bhatti, Nina; O'Brien-Strain, Eamonn; Liu, Jerry

2010-02-01

122

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

E-print Network

­4], and applying engineered diffraction patterns for structural illumination [5­7]. These microscope de- signsEffect of aberration on height calibration in three-dimensional localization-based microscopy of out-of-focus light with a pinhole, termed confocal microscopy [1], using nonlinearities

Petta, Jason

123

Cloud-based space situational awareness: initial design and evaluation  

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

124

Clouds  

NSDL National Science Digital Library

Created by Carl Wozniak, Clouds attempts to make the study of clouds and the processes of cloud formation more accessible for elementary and early secondary classroom study. The site accomplishes this by breaking information down into five sections, complemented by both descriptive text and relevant pictures. Pictures and graphics are perhaps the most classroom-friendly section of the site, as they are intended for use in non-profit, educational settings. Another primary section of the site is the glossary, aimed at explaining cloud-related terminology at a very simplistic level, understandable by younger students.

1999-01-01

125

Privacy-preserving Multi-keyword Text Search in the Cloud Supporting Similarity-based Ranking  

E-print Network

.00. Keywords Cloud Computing; Privacy-preserving Search; Multi-keyword Search; Similarity-based Ranking 1Privacy-preserving Multi-keyword Text Search in the Cloud Supporting Similarity-based Ranking With the increasing popularity of cloud computing, huge amount of documents are outsourced to the cloud for re- duced

Hou, Y. Thomas

126

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

127

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

128

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

129

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

130

Comparison of SEVIRI cloud fractional coverage and cloud top pressure with ground-based observations and corresponding MODIS products  

NASA Astrophysics Data System (ADS)

The Satellite Application Facility on Climate Monitoring (CM-SAF) is aiming to retrieve satellite-derived geophysical parameters suitable for climate monitoring (www.cmsaf.eu). CM- SAF started routine operations in early 2007 and provides a climatology of cloud parameters, radiation fluxes, surface albedo, and atmospheric water vapor, temperature and humidity pro- files on a regional and partially on a global scale. Here the focus was on the validation of cloud products derived from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) onboard the METEOSAT Second Generation (MSG) geostationary spacecraft. The time period studied covers the years 2006 and 2007. Cloud fractional coverage (CFC) products were validated against synoptic measurements, whereas SEVIRI cloud top pressure (CTP) results were compared with corresponding results derived from Moderate Resolution Imaging Spectrometer (MODIS) observations. Bias and Kuipers Skill Score (KSS) are used as quality indicators on pixel basis, while bias and standard deviation are used for the respective monthly mean values with 15x15 km2 resolution. Additionally, results of regional bias monitoring of the seasonal variability will be presented. The validation results show that CFC products from CM-SAF agree well with synoptic data over midlatitudes but SEVIRI overestimates the cloudiness towards the edges of the visible earth disk. Furthermore, CM-SAF satellite measurements are found to tend to overestimate the cloud coverage over sea whereas some underestimation is found over land. CTP validation results show that the cloud top pressure is generally considerably underestimated by SEVIRI, i.e. the cloud-top height is higher than that for corresponding MODIS observations. The bias is however remarkably small if only those pixels are analyzed where both cloud masks indicate a fully cloudy pixel. We conclude that a comparison of cloud-top pressure retrievals from different satellite sensors is mainly sensitive to cloud recognition which in turn is a function of spectral sampling, viewing geometry and the ground pixel size.

Lockhoff, Maarit; Reuter, Maximilian; Hollmann, Rainer; Weber, Ralf

131

Computing Entrainment Rates in Cloud Simulations Based on a Simple and Intuitive Definition of a Cloud  

NASA Astrophysics Data System (ADS)

Direct estimation of entrainment rates in cumulus clouds has proven to be a great challenge, even with the availability of high-resolution simulations. One of the main difficulties lies in setting reasonable boundaries to a simulated cloud. Although several methodologies have been proposed for this, these tend to use complex algorithms and the resulting cloud does not always correspond to the intuitive idea of a coherent cloudy air parcel. Here we present a new methodology for setting such boundaries in cloud resolving simulations, which is based on the simple concept of a coherent rising air parcel. Using this method we not only obtain entrainment rates consistent with previous studies, but we can also perform a detailed momentum budget on the rising thermals that allows us to assess the dynamical effects of mixing. Although such an individual-thermal approach may have limitations for determining bulk properties of convection, it is useful in terms of improving our understanding of the physical mechanisms behind the onset and development of deep convection.

Hernandez-Deckers, D.; Sherwood, S. C.; Robinson, F.

2012-12-01

132

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

133

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

USGS Publications Warehouse

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

Prejean, Stephanie G.; Brodsky, Emily E.

2011-01-01

134

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

135

The efficient data storage management system on cluster-based private cloud data center  

Microsoft Academic Search

The widespread popularity of Cloud computing as a preferred platform for the deployment of web applications has resulted in an enormous number of applications moving to the cloud, and the huge success of cloud service providers. The data center storage management plays a vital role in cloud computing environments. Especially the PC cluster-based data storage is necessary to manage data

Cho Cho Khaing; Thinn Thu Naing

2011-01-01

136

Daytime Arctic Cloud Detection based on Multi-angle Satellite Data with Case Studies  

E-print Network

Daytime Arctic Cloud Detection based on Multi-angle Satellite Data with Case Studies Tao Shi, Bin of these dependences requires accurate Arctic-wide measurements, especially of cloud coverage as gains or losses in cloud coverage can, in turn, affect surface air temperatures. Cloud detection in the Arctic is extremely

Yu, Bin

137

Community-Based Cloud for Emergency Management , Qingrui Li1  

E-print Network

Community-Based Cloud for Emergency Management Juan Li1 , Qingrui Li1 , Samee Ullah Khan2 , Nasir- scale emergency management. This infrastructure will coordinate various organizations and integrate and coordination of wide varieties of people and organizations. The data involved in emergency management includes

Li, Juan "Jen"

138

Exploiting Virtualization for Delivering Cloud-based IPTV Services  

E-print Network

Exploiting Virtualization for Delivering Cloud-based IPTV Services Vaneet Aggarwal, Xu Chen, Vijay resources on the fly. IPTV services like Video On Demand (VoD) and Live broadcast TV requires substantial constraints. By using real world data from an operational IPTV environment, our results show that anticipating

Fisher, Kathleen

139

A Blog Personality Recommender System Based on Cloud Computing Infrastructure  

Microsoft Academic Search

Blog is an important carrier of the current network information, and it has quick update, high quality and personalized characteristic. However, as the number of blogs increase sharply, it becomes more difficult to find high quality and personalized blog. In order to resolve this problem, this paper presents a new blog recommender system based on cloud computing infrastructure. This system

Jie Jiang; Weiwei Pang; Yule Deng; Kate He; Zhuyan Gu

2012-01-01

140

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

141

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.; Mendonca, Eneida A; Silverstein, Jonathan C.

2011-01-01

142

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

143

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

144

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

145

Intuitive terrain reconstruction using height observation-based ground segmentation and 3D object boundary estimation.  

PubMed

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

146

The predictive validity of body mass index based on self-reported weight and height.  

PubMed

In the Western society where obesity is a less desired condition it is natural that individuals may tend to report values of weight and height that they believe conform with current norms. Although several previous studies have shown that for the individual the difference between reported and controlled data may be small, such differences may affect body mass index distributions in various populations. The predictive validity of self-reported weight and height and of body mass index (BMI) calculated from these measures was analysed by using data from a random sample including 182 women with a mean age of 62 years (20-84 years) and 119 men with a mean age of 56 years (16-84 years) from a health care centre. Multiple multivariate linear regression analysis was used to study the relationship between self-reported (subjective) and controlled (objective) values. The regression lines of subjective parameters on controlled ones were significantly different from the line of identity for both sexes for weight, height and BMI (P less than 0.001). These lines demonstrate a 'flat slope syndrome', i.e. there is a systematic tendency for high values to be underestimated and for low ones to be overestimated. There was one exception for height in women, which was always overestimated, even for tall subjects. A systematic tendency for overweight and obese subjects to underestimate their body size and conversely for underweight subjects to overestimate it resulted in an incorrect BMI category distribution of 30 per cent of these subjects. This fact may invalidate data and conclusions of population surveys based on self-reported measures. PMID:2793299

Kuskowska-Wolk, A; Karlsson, P; Stolt, M; Rössner, S

1989-01-01

147

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

148

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, Remy; Abouelhoda, Mohamed

2013-01-01

149

Estimation of liquid water cloud height and fraction using simulated AMSU-A and MHS data. [Advanced Microwave Sounding Unit and Microwave Humidity Sounder  

NASA Technical Reports Server (NTRS)

The rms retrieval errors in cloud top pressure for fully overcast conditions over both land and water surfaces are shown for AMSU-A oxygen channel pair 3 and 5 and MHS water vapor channel pair 4 and 5. For both pairs, the decrease of retrieval skill from high cloud is evident for almost all liquid water contents. For high cloud and medium cloud, the water vapor pair outperforms the oxygen pair. Retrieval accuracy is the best for high and middle clouds and degrades as the cloud top is lower in the atmosphere.

Huang, Hung-Lung; Diak, George R.

1992-01-01

150

Wave Height Characteristics in the North Atlantic Ocean: A new approach based on Statistical and Geometrical techniques  

E-print Network

Characteristics in the North Atlantic Ocean: A new approach based on Statistical and Geometrical techniques George of the significant wave height in an area of increased interest, the north Atlantic ocean, are studied based

Dodson, C.T.J.

151

Cloud based metalearning system for predictive modeling of biomedical data.  

PubMed

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

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

2014-01-01

152

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

Vukicevic, Milan

2014-01-01

153

A physical-based statistical method for modeling ocean wave heights  

NASA Astrophysics Data System (ADS)

This study proposes a computationally inexpensive statistical method for modeling ocean wave heights, focusing particularly on modeling wave heights in near-shore areas. A multiple linear regression is used to predict significant wave heights (Hs) using predictors derived from the sea level pressure (SLP) field, including the use of squared SLP gradients to represent geostrophic winds. One time step lagged Hs is also included as a predictor, which could be interpreted as the first order derivative in the spectral energy balance governing equation. Further, based on the frequency/directional dispersion theory of waves, the swell component is accounted for by using a set of selected principal components derived from the squared SLP gradient vectors (including magnitudes and directions). The effect of non-Gaussian (non-negative) variables is also assessed by applying two types of transformation to the data. The proposed method is evaluated and shown to have good skills for the study area (Catalan coast). This method can be used to project possible future wave climate change for use in coastal impact assessment studies. It is used in this study to project the wave climate for the study area that corresponds to 5 sets of regional climate model (RCM) atmospheric projections, which were made by different RCMs forced by the same global circulation model (GCM), or by the same RCM forced by two GCMs. For the season analyzed (winter), the results show that the uncertainty due to using different GCMs to drive the same RCM is greater than that due to using different RCMs driven by the same GCM.

Casas-Prat, Mercè; Wang, Xiaolan L.; Sierra, Joan P.

2014-01-01

154

A new retrieval for cloud liquid water path using a ground-based microwave radiometer and measurements of cloud temperature.  

SciTech Connect

A new method to retrieve cloud liquid water path using 23.8 and 31.4 GHz microwave radiometer brightness temperature measurements is developed. This method does not depend on climatological estimates of either the mean radiating temperature of the atmosphere T{sub mr} or the mean cloud liquid water temperature T{sub cloud}. Rather, T{sub mr} is estimated from surface temperature and relative humidity measurements, while T{sub cloud} is estimated using millimeter-wave cloud radar data, together with atmospheric temperature profiles obtained from either radiosonde or rapid update cycle (RUC) model output. Simulations demonstrate that the new retrieval method significantly reduces the biases in the liquid water path estimates that are apparent in a site-specific retrieval based on monthly stratified, local climatology. An analysis of the liquid water path estimates produced by the two retrievals over four case study days illustrates trends and retrieval performances consistent with the model simulations.

Liljegren, J. C.; Clothiaux, E. E.; Mace, G. G.; Kato, S.; Dong, X.; Environmental Research; Pennsylvania State Univ.; Univ. of Utah; Hampton Univ.

2001-07-16

155

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

156

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)

157

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

E-print Network

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

Paris-Sud XI, Université de

158

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

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

159

Parameterizations of Cloud-Radiation Interactions Based on Detailed Cloud Microphysics  

Microsoft Academic Search

Cloud-radiation effects still account for much of the variation among leading global climate models in sensitivity to greenhouse gases. A single-column model (SCM) allows results of different cloud-radiation parameterizations to be compared directly with measurements. The relevant fields include cloud altitude, cloud amount, liquid and ice content, particle size spectra, and radiative fluxes at the surface and the top of

S. F. Iacobellis; R. C. Somerville; G. M. McFarquhar; D. Mitchell

2002-01-01

160

Physically-Based General Circulation Model Parameterization of Clouds and Their Radiative Interaction.  

NASA Astrophysics Data System (ADS)

A physically-based parameterization of clouds and their radiative interactions has been developed for a multilayer atmospheric general circulation model. The main purpose of this development is to enable the evaluation of cloud optical depth feedback, a feedback of potential importance for greenhouse-gas-induced climate change. The parameters for the stratiform-cloud parameterization and the values chosen are: (1) the characteristic time for the evaporation of cloud water, tau = 50 minutes; (2) the autoconversion rate of cloud water into precipitation, a = (3600 s)^{ -1}; (3) the threshold relative humidity of the environment at which condensation can begin, U _{00} = 0; and (4) the threshold cloud water above which precipitation can begin, m _{rm c,w} = 0.5 times 10^{-4} g/g for water clouds; m_{rm c,i } = 0.4 times I _{rm c}(T_ {rm c}) for ice clouds, where I _{rm c}(T _{rm c}) are the values given by Heymsfield and Platt (1984) as a function of the cloud temperature T_{rm c}; m_{rm m,c} = 1.2 times I_{rm c}(T_{rm c} ) for ice clouds formed from an antecedent cumuloform cloud. The parameters for the cumuloform-cloud parameterization and the values chosen are: (1) the characteristic time for the evaporation of cloud water, tau = 50 minutes; (2) the parameter in the diagnostic equation for the cloudiness in terms of the mass flux at the base of the detrainment layer, alpha = 10; and (3) the conversion rate of cloud water into precipitation, C_0 = 0.002 m^{ -1}. In addition, two radiation parameters were determined: (1) the mass absorption coefficient of cumuloform ice clouds, a_sp {0} {uparrow,downarrow} = 0.096; and (2) the multiple-scattering asymmetry factor for cumuloform clouds, g = 0.85. An evaluation of the performance of the model shows that the cloud-radiation parameterization is capable of successfully simulating many features of the observed cloud cover, the vertically integrated cloud water, precipitation, and the earth's radiation budget at the top of the atmosphere. The model is less successful in reproducing the cloud optical depths as given by the International Satellite Cloud Climatology Project observations. This apparent contradiction suggests that these optical depth observations may not be useful in validating a cloud-radiation parameterization. The comparison of the simulated and observed climates also shows that the cloud parameterization is deficient in its reproduction of the subtropical stratocumulus clouds. To rectify this deficiency it is necessary to develop a model for stratocumulus clouds in the cloud-radiation parameterization. (Abstract shortened with permission of author.).

Oh, Jai-Ho.

161

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

162

High-speed nuclear quality pulse height analyzer for synchrotron-based applications  

SciTech Connect

A high throughput Pulse Height Analyzer system for synchrotron-based applications requiring high resolution, high processing speed and low dead time has been developed. The system is comprised of a 120ns 12-bit nuclear quality Analog to Digital converter with a self-adaptive fast peak detector-stretcher and a custom-made fast histogramming memory module that records and processes the digitized data. The histogramming module is packaged in a VME or VXI compatible interface. Data is transferred through a fast optical link from the memory interface to a computer. A dedicated data acquisition program matches the hardware characteristics of the histogramming memory module. The data acquisition system allows for two data collection modes: ''standard'' data acquisition mode where the data is accumulated and read in synchronization with an external trigger and ''live'' data acquisition mode where the system operates as a standard Pulse Height Analyzer. The acquisition, standard or live, can be performed on several channels simultaneously. A two-channel prototype has been demonstrated at the Stanford Synchrotron Radiation Laboratory accelerator in conjunction with an X-ray Fluorescence Absorption Spectroscopy experiment. A detailed description of the entire system is given and experimental data is shown.

Beche, Jean-Francois; Bucher, Jerome J.; Fabris, Lorenzo; Riot, Vincent J.

2001-04-01

163

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

164

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

165

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.

Costulis, P.

2002-09-30

166

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

167

Improved retrievals of cloud boundaries from MODIS for use in air quality modeling  

NASA Astrophysics Data System (ADS)

A new approach has been developed at the Center for Space Research (CSR) to determine cloud boundaries from satellite data for use in air quality modeling. The approach combines remotely sensed cloud thickness, obtained from the MODIS cloud optical property products, with cloud base height measurements made at surface weather observing facilities to determine cloud top height. When compared to cloud truth estimates, compiled from measurements made at the Southern Great Plains Atmospheric Radiation Measurement Site in Oklahoma, errors in cloud top height from this new method were found to be significantly smaller than those in the MODIS (MOD06) cloud product. It was also found that relatively small errors in MOD06 cloud top temperatures can be magnified in MOD06 cloud top pressures because the interpolation scheme appears to not adequately consider humidity profiles in the NCEP data used to make these conversions.

Hutchison, Keith D.; Pekker, Tatyana; Smith, Solar

168

A Distributed Key Based Security Framework for Private Clouds  

Microsoft Academic Search

Cloud computing in its various forms continues to grow in popularity as organizations of all sizes seek to capitalize on the cloud’s scalability, externalization of infrastructure and administration and generally reduced application deployment costs. But while the attractiveness of these public cloud services is obvious, the ability to capitalize on these benefits is significantly limited for those organization requiring high

Ali Shahbazi; Julian Brinkley; Ali Karahroudy; Nasseh Tabrizi

2013-01-01

169

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

170

Investigation of Aerosol-Cloud Interactions based on Satellite Based Remote Sensing in Northeast Asia  

NASA Astrophysics Data System (ADS)

The subject of aerosol-cloud interactions has received prominent attention because of still higher uncertainty in estimating its climatic forcings and its possible climatic implications. Although the various studies on the aerosol indirect effect have been carried out all over the world, relatively few focuses have been put on the Northeast Asian region, which has suffered from a lot of anthropogenic air pollution and various kinds of aerosol compositions. Detailed and integrated careful observations are needed to understand the complex coupled mechanisms of aerosol-cloud interaction and its radiative forcing, but these strategies have not been applied to the region yet. The first step to aerosol indirect study in Northeast Asia is to have an overall understanding of the current state of aerosol and cloud optical properties derived from ground and satellite-based remote sensings available since 2001. First of all, there seem to be no annual increasing/decreasing trends of monthly-average aerosol optical depth (AOD) from MODIS in the downstream region of China, which is also confirmed by the aerosol robotic network (AERONET). In general, AOD showed the strong horizontal gradient from China to Korea, with no relevant systematic association with the effective radius and optical depth of the liquid-phase cloud, which might be attributable to the masking synoptic meteorological variations and the coarse horizontal grid (1 deg by 1 deg). Specific comparisons of AOD and the effective radius demonstrated the significant negative correlation only in summer and over the Yellow Sea, where the relative variability of cloud (e.g. cloud optical depth) appears to be suppressed and aerosol loadings tend to be significantly variable relative to other regions and other seasons, which could indicate the seasonal and spatial sensitivity of aerosol-cloud interactions. With regard to the cloud scale in addition to the above climatic perspective, an association of the cloud with aerosols has been eventually examined using Atmospheric Brown Cloud data in March 2005.

Kim, B.-G.; Kim, Y.-J.; Ho, C.-H.; Kim, S.-W.

2009-04-01

171

CloudSat Preps for Launch at Vandenberg Air Force Base, CA  

NASA Technical Reports Server (NTRS)

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

2005-01-01

172

Thin apps store for smart phones based on private cloud infrastructure  

Microsoft Academic Search

A novel approach to implement cloud computing for smart phone devices has been presented based on Eucalyptus, an open source cloud-computing framework that provides infrastructure as a service (IaaS). It has full support of Virtualization and is Amazon Web Services interface compatible. A private cloud has been designed using Eucalyptus to develop a smart phone application store. The architecture, physical

Ashish Tanwer; Abhishek Tayal; Muzahid Hussain; Parminder Singh Reel

2010-01-01

173

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 1. Introduction The microphysical and optical properties of liquid water clouds are important parameters for studying cloud­radiation interactions. The amount of liquid water droplets, their particle

Haak, Hein

174

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

E-print Network

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

Pedram, Massoud

175

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

176

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

E-print Network

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

Schneider, Jean-Guy

177

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

E-print Network

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

Pedram, Massoud

178

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

179

Daytime Arctic Cloud Detection Based on Multi-Angle Satellite Data With Case Studies  

E-print Network

Daytime Arctic Cloud Detection Based on Multi-Angle Satellite Data With Case Studies Tao SHI, Bin in the Arctic. A systematic study of these dependences requires accurate Arctic-wide measurements, especially of cloud coverage. Thus cloud detection in the Arctic is extremely important, but it is also challenging

Shi, Tao

180

Enhanced aerosol backscatter adjacent to tropical trade wind clouds revealed by satellite-based lidar  

Microsoft Academic Search

sensing with lidar offers several advantages over passive instruments, including range-resolved backscattered radian- ces, better cloud detection, and essentially no 3-D radiative cloud-adjacency effects when operated at night. Two notable studies used lidar to observe how aerosol properties change near cloud edge. The first and earliest study qualitatively reported an aerosol backscatter increase near two clouds from a ground-based lidar

Jason Lucas Tackett; Larry Di Girolamo

2009-01-01

181

Anion height dependence of T c and the density of states in iron-based superconductors  

NASA Astrophysics Data System (ADS)

Systematic ab initio LDA calculations were performed for all the typical representatives of recently discovered class of iron-based high-temperature superconductors: REOFe(As,P) (RE = La, Ce, Nd, Sm, Tb), Ba2Fe2As, (Sr,Ca)FFeAs, Sr4Sc2O6Fe2P2, LiFeAs and Fe(Se,Te). Non-monotonic behavior of total density of states at the Fermi level is observed as a function of anion height relative to Fe layer with maximum at about ? z a ˜ 1.37 Å, attributed to changing Fe-As (P, Se, Te) hybridization. This leads to a similar dependence of superconducting transition temperature T c as observed in the experiments. The fit of this dependence to elementary BCS theory produces semiquantitative agreement with experimental data for T c for the whole class of iron-based superconductors. The similar fit to Allen-Dynes formula underestimates T c in the vicinity of the maximum, signifying the possible importance of non-phonon pairing in this region. These results unambiguously demonstrate that the main effect of T c variation between different types of iron-based superconductors is due to the corresponding variation of the density of states at the Fermi level.

Kuchinskii, E. Z.; Nekrasov, I. A.; Sadovskii, M. V.

2010-05-01

182

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

183

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

NASA Astrophysics Data System (ADS)

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

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

2006-12-01

184

User-based CPU Verification Scheme for Public Cloud Computing  

E-print Network

scheme is proposed for cloud cheating detection. In this scheme, a predefined computational task is constructed for the cloud to execute in our cheating detection process. Then we compare the difference the cloud is cheating or not. A time-lock puzzle is introduced to construct the predefined computational

Wu, Jie

185

Data Mining of Mass Storage Based on Cloud Computing  

Microsoft Academic Search

Cloud computing is an elastic computing model that the users can lease the resources from the rentable infrastructure. Cloud computing is gaining popularity due to its lower cost, high reliability and huge availability. To utilize the powerful and huge capability of cloud computing, this paper is to import it into data mining and machine learning field. As one of the

Jianzong Wang; Jiguang Wan; Zhuo Liu; Peng Wang

2010-01-01

186

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

187

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

188

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

189

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

NASA Technical Reports Server (NTRS)

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

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

2008-01-01

190

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

191

CloudWF: A Computational Workflow System for Clouds Based on Hadoop  

NASA Astrophysics Data System (ADS)

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

Zhang, Chen; de Sterck, Hans

192

Study of the relations between cloud properties and atmospheric conditions using ground-based digital images  

NASA Astrophysics Data System (ADS)

The aerosol constituents of the earth atmosphere are of great significance for the radiation budget and global climate of the planet. They are the precursors of clouds that in turn play an essential role in these processes and in the hydrological cycle of the Earth. Understanding the complex aerosol-cloud interactions requires a detailed knowledge of the dynamical processes moving the water vapor through the atmosphere, and of the physical mechanisms involved in the formation and growth of cloud particles. Ground-based observations on regional and short time scale provide valuable detailed information about atmospheric dynamics and cloud properties, and are used as a complementary tool to the global satellite observations. The objective of the present paper is to study the physical properties of clouds as displayed in ground-based visible images, and juxtapose them to the specific surface and atmospheric meteorological conditions. The observations are being carried out over the urban area of the city of Sofia, Bulgaria. The data obtained from visible images of clouds enable a quantitative description of texture and morphological features of clouds such as shape, thickness, motion, etc. These characteristics are related to cloud microphysical properties. The changes of relative humidity and the horizontal visibility are considered to be representative of the variations of the type (natural/manmade) and amount of the atmospheric aerosols near the earth surface, and potentially, the cloud drop number concentration. The atmospheric dynamics is accounted for by means of the values of the atmospheric pressure, temperature, wind velocity, etc., observed at the earth's surface. The advantage of ground-based observations of clouds compared to satellite ones is in the high spatial and temporal resolution of the obtained data about the lowermost cloud layer, which in turn is sensitive to the meteorological regimes that determine cloud formation and evolution. It turns out that the visible features of clouds reflect closely the meteorological parameters and their dynamics. There are evidences that time intervals between measurements as short as several minutes may be indicative of the trend of evolution of certain types of clouds. The results show that after taking into consideration the corrections due to the influence of cloud edges on light scattering, the observable changes of cloud properties are in agreement with the follow-up weather. This allows for scrutinizing cloud properties and their relationship with surface and atmospheric properties. The remote sensing of the variations of cloud optical properties by means of visible images taken from earth's surface can help to establish some complex atmospheric interactions and contribute to our knowledge of aerosol and cloud climatology. Acknowledgement: The work is partially supported by the Bulgarian NFSR under contract NZ-1414/04.

Bakalova, Kalinka

193

Management of Data Replication for PC Cluster-based Cloud Storage System  

E-print Network

Storage systems are essential building blocks for cloud computing infrastructures. Although high performance storage servers are the ultimate solution for cloud storage, the implementation of inexpensive storage system remains an open issue. To address this problem, the efficient cloud storage system is implemented with inexpensive and commodity computer nodes that are organized into PC cluster based datacenter. Hadoop Distributed File System (HDFS) is an open source cloud based storage platform and designed to be deployed in low-cost hardware. PC Cluster based Cloud Storage System is implemented with HDFS by enhancing replication management scheme. Data objects are distributed and replicated in a cluster of commodity nodes located in the cloud. This system provides optimum replica number as well as weighting and balancing among the storage server nodes. The experimental results show that storage can be balanced depending on the available disk space, expected availability and failure probability of each node ...

Myint, Julia

2011-01-01

194

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

Fernandez, Gonzalo; Lopez-Coronado, Miguel

2013-01-01

195

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

196

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

197

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

198

Cloud Service Solving N-Body Problem Based on Windows Azure Platform  

NASA Astrophysics Data System (ADS)

This paper shows how to use cloud computing to solve N-body problem. It presents an idea and implementation of cloud service based on Windows Azure Platform. Clients can access cloud service via Internet over HTTP protocol. They create computation tasks supplying simulation parameters such as number of steps, time step and XML file with body definitions (initial position, mass and velocity). Presented solution uses Barnes-Hut Algorithm (based on adaptive oct tree) to reduce computation complexity form N ×N to N logN. All body interactions are computed in parallel, on worker nodes in cloud.

Augustyn, Dariusz Rafa?; Warcha?, ?ukasz

199

Dealing with clouds from space-based ultraspectral IR observations  

NASA Astrophysics Data System (ADS)

Hyperspectral infrared sounders with nadir observations are limited by the cloud cover It is critical to detect the clouds in satellite measurements and to accurately retrieve the atmospheric and surface parameters with cloud contamination measurements An inversion scheme has been developed dealing with cloudy as well as cloud-free radiances observed with ultraspectral infrared sounders to simultaneously retrieve surface atmospheric thermodynamic and cloud microphysical parameters A fast radiative transfer model which applies to the clouded atmosphere is used for atmospheric profile and cloud parameter retrieval A one-dimensional 1-d variational multi-variable inversion solution is used to iteratively improve the background state defined by an eigenvector-regression-retrieval The solution is iterated in order to account for non-linearity in the 1-d variational solution NPOESS Airborne Sounder Testbed -- Interferometer NAST-I retrievals are compared with coincident observations obtained from dropsondes and the nadir-pointing Cloud Physics Lidar CPL This work was motivated by the need to obtain solutions for atmospheric soundings from infrared radiances observed for every individual field of view regardless of cloud cover from future ultraspectral geostationary satellite sounding instruments such as the Geosynchronous Imaging Fourier Transform Spectrometer GIFTS and the Hyperspectral Environmental Suite HES However this retrieval approach can also be applied to the ultraspectral sounding instruments to fly on polar satellites such

Zhou, D.; Smith, W.; Liu, X.; Larar, A.; Mango, S.; Huang, H.-L.

200

Fly Height Measurement Based on Phase Comparison Michelson Interferometry Using Low-Coherence Light Source  

Microsoft Academic Search

We present a method for measuring head fly height in hard disk drives using phase comparison Michelson interferometry (PCMI), which compares the phases of two interference fringe patterns formed respectively on the inner surface of a glass disk and the air-bearing surface of a fly head slider through the glass disk. To suppress interference noise and further enhance measurement accuracy,

Yinbo He; Hedong Zhang; Kenji Fukuzawa; Yasunaga Mitsuya

2008-01-01

201

3-D Command state-based modifiable walking of a humanoid robot on uneven terrain with different inclinations and heights  

Microsoft Academic Search

This paper proposes 3-D command state (3-D CS)-based modifiable walking pattern generator (MWPG) on the uneven terrain with the different inclinations and heights for humanoid robots. In the previous researches on walking pattern generation on the uneven terrain, the humanoid robot was unable to modify a walking pattern on the uneven terrain without any additional footstep for adjusting the center

Young-Dae Hong; Jong-Hwan Kim

2011-01-01

202

Comparison of Weight and Height-based Indices for Assessing the Risk of Death in Severely Malnourished Children  

Microsoft Academic Search

To compare the effectiveness of treating malnourished children in different centers, the authors believe there is a need to have a simple method of adjusting mortality rates so that differences in the nutritional status of the children are taken into account. The authors compared different anthropometric indices based on weight and height to predict the risk of death among severely

C. Prudhon; A. Briend; D. Laurier; M. H. N. Golden; J. Y. Mary

203

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

204

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

205

Characteristics of Borneo and Sumatra fire plume heights and smoke clouds and their impact on regional El Niño-induced drought  

Microsoft Academic Search

During the dry season, anthropogenic fires burn the tropical forests and peatlands of equatorial Asia and produce regionally expansive smoke clouds. We estimated the altitude of smoke from these fires, characterized the sensitivity of this smoke to regional drought and El Niño variability, and investigated its effect on climate. We used the MISR satellite product and MISR INteractive eXplorer (MINX)

Michael Tosca; James Randerson; Charles Zender; Mark Flanner; David Nelson; David Diner; Phil Rasch; Jennifer Logan

2010-01-01

206

Point Cloud Simplification Based on an Affinity Propagation Clustering Algorithm  

Microsoft Academic Search

Point cloud simplification is an important step in reverse engineering and computer vision. Nowadays many researchers are directly working on point sets other than polygonal meshes, while some nasty problems still exist, such as time cost, memory cost and accuracy. This paper proposes a novel method for point cloud simplification by integrating both re-sampling and Affinity Propagation Clustering. The advantage

Lanlan Li; S. Y. Chen; Qiu Guan; Xiaoyan Du; Z. Z. Hu

2009-01-01

207

A cryptography based privacy preserving solution to mine cloud data  

Microsoft Academic Search

Due to increased adoption of cloud computing, there is a growing need of addressing the data privacy during mining. On the other hand, knowledge sharing is a key to survive many business organizations. Several attempts have been made to mine the data in distributed environment however, maintaining the privacy while mining the data over cloud is a challenging task. In

Meena Dilip Singh; P. Radha Krishna; Ashutosh Saxena

2010-01-01

208

Cloud droplet size distributions in low-level stratiform clouds  

SciTech Connect

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

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

2000-01-15

209

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

210

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

211

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

212

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

213

A cloud climatology of the Southern Great Plains ARM CART  

SciTech Connect

Cloud amount statistics from three different sources were processed and compared. Surface observations from a National Centers for Environmental Prediction dataset were used. The data (Edited Cloud Report; ECR) consist of synoptic weather reports that have been edited to facilitate cloud analysis. Two stations near the Southern Great Plains (SGP) Cloud and Radiation Test Bed (CART) in north-central Oklahoma (Oklahoma City, Oklahoma and Wichita, Kansas) were selected. The ECR data span a 10-yr period from December 1981 to November 1991. The International Satellite Cloud Climatology Project (ISCCP) provided cloud amounts over the SGP CART for an 8-yr period (1983--91). Cloud amounts were also obtained from Micro Pulse Lidar (MPL) and Belfort Ceilometer (BLC) cloud-base height measurements made at the SGP CART over a 1-yr period. The annual and diurnal cycles of cloud amount as a function of cloud height and type were analyzed. The three datasets closely agree for total cloud amount. Good agreement was found in the ECR and MPL-BLC monthly low cloud amounts. With the exception of summer and midday in other seasons, the ISCCP low cloud amount estimates are generally 5%--10% less than the others. The ECR high cloud amount estimates are typically 10%--15% greater than those obtained from either the ISCCP or MPL-BLC datasets. The observed diurnal variations of altocumulus support the authors' model results of radiatively induced circulations.

Lazarus, S.M.; Krueger, S.K.; Mace, G.G.

2000-05-15

214

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

215

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

216

Mystery of ice multiplication in warm-based precipitating shallow cumulus clouds  

Microsoft Academic Search

High concentrations of ice crystals exceeding those of background ice nuclei have often been observed in warm-based precipitating shallow cumulus clouds. Laboratory experiments reveal that such ice multiplication can occur when large ice particles collide with cloud droplets (Hallett-Mossop mechanism). Further studies suggested that this mechanism is unable to account for the exceedingly high ice concentrations in those kinds of

Jiming Sun; Parisa A. Ariya; Henry G. Leighton; M. K. Yau

2010-01-01

217

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

218

Study on the Network Service Status's Detection and Recovery Strategy Based on Cloud Model  

Microsoft Academic Search

In this paper, taking the survivability of trusted network as the background, the key issues of network survivability are researched. Taking into account the uncertainty, randomness of network services, by introducing cloud model, the status of network service is described in this paper. Based on cloud model, this paper proposes the strategy of status detection for network service, the evaluation

Chen Lin; Zhang Shi-bin; Li Li

2009-01-01

219

Based on Private Matching and Min-attribute Generalization for Privacy Preserving in Cloud Computing  

Microsoft Academic Search

When our private data are out-sourced in cloud computing, we should guarantee the confidentiality and search ability of the private data. However, nowadays privacy preserving issues in the cloud have not been carefully explored at current stage. To relieve individuals' concerns of their data privacy, this paper explores a new approach based on private matching and min-attribute generalization to solve

Jian Wang; Jiajin Le

2010-01-01

220

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 computation and storage resources for e- learning ecosystems. Cloud computing is a promising infrastructure

Li, Haifei

221

AN ARSCL-BASED CLOUD TYPE CLIMATOLOGY FROM RETRIEVALS AND IT'S USE IN MODEL EVALUATION STUDIES  

E-print Network

AN ARSCL-BASED CLOUD TYPE CLIMATOLOGY FROM RETRIEVALS AND IT'S USE IN MODEL EVALUATION STUDIES Laboratory P.O. Box, Upton, NY www.bnl.gov ABSTRACT A climatology of cloud types is developed using long-term (6.5 years) ARSCL data at the ARM SGP site. The primary goal of the derived climatology is to be used

222

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

223

Information Stewardship in the Cloud: A Model-based Approach  

E-print Network

for (the rapidly growing) cyber-crime threat, inhibiting the effective deployment of cloud computing. To-date and policy-makers. Without this there is a significant danger of leaving vulnerabil- ities and opportunites

Pym, David J.

224

Cloud detection based on decision tree over Tibetan Plateau with MODIS data  

NASA Astrophysics Data System (ADS)

Snow cover area is a very critical parameter for hydrologic cycle of the Earth. Furthermore, it will be a key factor for the effect of the climate change. An unbelievable situation in mapping snow cover is the existence of clouds. Clouds can easily be found in any image from satellite, because clouds are bright and white in the visible wavelengths. But it is not the case when there is snow or ice in the background. It is similar spectral appearance of snow and clouds. Many cloud decision methods are built on decision trees. The decision trees were designed based on empirical studies and simulations. In this paper a classification trees were used to build the decision tree. And then with a great deal repeating scenes coming from the same area the cloud pixel can be replaced by "its" real surface types, such as snow pixel or vegetation or water. The effect of the cloud can be distinguished in the short wave infrared. The results show that most cloud coverage being removed. A validation was carried out for all subsequent steps. It led to the removal of all remaining cloud cover. The results show that the decision tree method performed satisfied.

Xu, Lina; Niu, Ruiqing; Fang, Shenghui; Dong, Yanfang

2013-10-01

225

Cloud Detection Based on Decision Tree Over Tibetan Plateau with Modis Data  

NASA Astrophysics Data System (ADS)

Snow cover area is a very critical parameter for hydrologic cycle of the Earth. Furthermore, it will be a key factor for the effect of the climate change. An unbelievable situation in mapping snow cover is the existence of clouds. Clouds can easily be found in any image from satellite, because clouds are bright and white in the visible wavelengths. But it is not the case when there is snow or ice in the background. It is similar spectral appearance of snow and clouds. Many cloud decision methods are built on decision trees. The decision trees were designed based on empirical studies and simulations. In this paper a classification trees were used to build the decision tree. And then with a great deal repeating scenes coming from the same area the cloud pixel can be replaced by "its" real surface types, such as snow pixel or vegetation or water. The effect of the cloud can be distinguished in the short wave infrared. The results show that most cloud coverage being removed. A validation was carried out for all subsequent steps. It led to the removal of all remaining cloud cover. The results show that the decision tree method performed satisfied.

Xu, L.; Fang, S.; Niu, R.; Li, J.

2012-07-01

226

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

E-print Network

#11;ering in river and lake beds #12; Acid Fogs: pH 2-3 #15; Unusual cloud chemistry due to fog: coastlines #15; Can lead to very acid water: London fog of January, 1955 caused 4; 000 deaths! 1. Fog over ocean in humid air: Largely H 2 O condensed on sea-salt (NaCl) aerosols NaCl #1; nH 2 O 2. Fog moves

Schofield, Jeremy

227

Spatial distribution of cloud overlap parameter: assessment based on satellite data  

NASA Astrophysics Data System (ADS)

Assumptions on cloud overlap implemented in a climate model may affect markedly modeled radiative fluxes. To increase the ability of climate models to simulate the real climate, it is preferable to know the value of the cloud overlap parameter ? which is a measure of the relative weight of maximum (? = 1) and random (? = 0) overlap. This parameter may be used to diagnose relative contribution of convective and stratiform cloudiness to total cloud fraction. Here we present an estimate of geographical distribution of ? derived from up-to-date satellite observations. To assess values of total cloud fraction, we used cloud masks CERES and MODIS, which both are based on multispectral passive observations from Aqua satellite (CERES SSF product and MODIS collection 5.1). Active CALIOP lidar observations were used to evaluate cloud fraction at different levels (CALIPSO-GOCCP dataset). Cloud overlap parameter ? was calculated by merging passive and active satellite datasets. Only monthly means for 2006-2010 were used in these calculations. The most prominent annual cycle of ? is noted in the monsoon regions where ? is close to 1 in winter and almost 0 in summer. For CERES total cloud fraction, ? is equal to 0.36 in July (0.38 in January) for the entire Earth, it is 0.39 (0.44) in Northern Hemisphere and 0.33 (0.33) in Southern Hemisphere. Values of ? are lower when MODIS total cloud fraction is used: global annual mean ? is 0.37 for CERES and 0.25 for MODIS. We found that ? is linearly dependent on total cloud fraction in most regions, except in the southern tropics. The maximum cloud overlap (? is close to 1) is associated with small values of cloud fraction and occurs in subtropical highs over the ocean and in subtropical and polar deserts over land. On the other hand, the random cloud overlap (? is close to 0) occurs in regions with large values of cloud fraction (e.g. ITCZ and midlatitudinal storm tracks). Moreover, we found that vast regions of the Southern Ocean (around 60S) are characterized by negative values of ?, mostly in summer. Presumably, an assumption of the minimum overlap of cloud layers should be used in these regions due to strong baroclinic instability and horizontal shift of cloud layers. The work has been supported by the grant of the RF President MK-3259.2012.5 and by the Russian Foundation of Basic Research under grant 12-05-00972.

Chernokulsky, Alexander; Eliseev, Alexey

2013-04-01

228

Cumulus Cloud Transport of Transient Tracers  

Microsoft Academic Search

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.

Louis T. Gidel

1983-01-01

229

Height estimates using AATSR dual view  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

230

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

231

Cloud-property retrieval using merged HIRS and AVHRR data  

NASA Technical Reports Server (NTRS)

A technique is developed that uses a multispectral, multiresolution method to improve the overall retrieval of mid- to high-level cloud properties by combining HIRS sounding channel data with higher spatial resolution AVHRR radiometric data collocated with the HIRS footprint. Cirrus cloud radiative and physical properties are determined using satellite data, surface-based measurements provided by rawinsondes and lidar, and aircraft-based lidar data collected during the First International Satellite Cloud Climatology Program Regional Experiment in Wisconsin during the months of October and November 1986. HIRS cloud-height retrievals are compared to ground-based lidar and aircraft lidar when possible. Retrieved cloud heights are found to have close agreement with lidar for thin cloud, but are higher than lidar for optically thick cloud. The results of the reflectance-emittance relationships derived are compared to theoretical scattering model results for both water-droplet spheres and randomly oriented hexagonal ice crystals. It is found that the assumption of 10-micron water droplets is inadequate to describe the reflectance-emittance relationship for the ice clouds seen here. Use of this assumption would lead to lower cloud heights using the ISCCP approach. The theoretical results show that use of hexagonal ice crystal phase functions could lead to much improved results for cloud retrieval algorithms using a bispectral approach.

Baum, Bryan A.; Wielicki, Bruce A.; Minnis, Patrick; Parker, Lindsay

1992-01-01

232

Development and Application of a Satellite-based Convective Cloud Object-Tracking Methodology: A Multipurpose Data Fusion Tool  

E-print Network

1 Development and Application of a Satellite-based Convective Cloud Object-Tracking Methodology cloud-objects from convective cloud infancy (as few as 3 GOES infrared (IR) pixels) into the mature (WDSS-II) object tracking capabilities. The system uses an IR- window based field as input to WDSS

Lakshmanan, Valliappa

233

Arctic-Winter Climatology and Radiative Effects of Clouds and Aerosols Based on Lidar and Radar Measurements at PEARL  

E-print Network

Arctic-Winter Climatology and Radiative Effects of Clouds and Aerosols Based on Lidar and Radar Atmospheric Radiative Transfer (SBDART) code. Results on the climatology and radiative effects of clouds

Eloranta, Edwin W.

234

Calibration and Unfolding of the Pulse Height Spectra of Liquid Scintillator-Based Neutron Detectors Using Photon Sources  

NASA Astrophysics Data System (ADS)

An accurate energy calibration of a 5? × 2? BC501A liquid scintillator-based neutron detector by means of photon sources and the unfolding of pulse height spectra are described. The photon responses were measured with 22Na, 137Cs and 54Mn photon sources and simulated using the GRESP code, which was developed at the Physikalisch Technische Bundesanstalt in Germany. Pulse height spectra produced by three different photon sources were employed to investigate the effects of the unfolding techniques. It was found that the four unfolding codes of the HEPRO and UMG3.3 packages, including GRAVEL, UNFANA, MIEKE and MAXED, performed well with the test spectra and produced generally consistent results. They could therefore be used to obtain neutron energy spectra in tokamak experiments.

Xie, Xufei; Yuan, Xi; Zhang, Xing; Fan, Tieshuan; Chen, Jinxiang; Li, Xiangqing

2012-06-01

235

Prediction Based Proactive Thermal Virtual Machine Scheduling in Green Clouds  

PubMed Central

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

236

CloudSat-CALIPSO characterizations of cloud during the active and the break periods of Indian summer monsoon  

NASA Astrophysics Data System (ADS)

Here we report cloud macrophysical (cloud top height (CTH), cloud base height (CBH), cloud geometrical depth), microphysical (liquid and ice water contents, water paths, effective radii and number concentration) and radiative (heating rate) properties over the North Central India (18-28°N, 65-88°E) region (core monsoon zone) during the active and the break periods (2006-2010) of the Indian summer monsoon (ISM). Synergetic data from the CloudSat radar and the CALIPSO lidar are used. Analysis shows that the CTH and CBH have bimodal distributions during both the phases of monsoon. We have classified clouds into four type's viz., high-, mid-, low- and vertically extended deep clouds. The low-level clouds and optically thick cirrus are more dominant of the total observations and they occur more frequently during the active period compared to that of the break period. In contrast, the high-level clouds and optically thin cirrus are more frequent during the break phase of monsoon. The integrated depolarization ratio of high-level cloud exhibits bimodal distribution. It is observed that there is a significant variation in macrophysical, microphysical, optical and radiative properties of all the four types of clouds during the active and the break periods. As little observational evidence exists in the vertical structure of clouds during the active and the break periods of the ISM, the current results would be useful in understanding the characteristics of monsoon clouds, which have implications in the Earth's radiation budget and global climate models.

Das, Subrata Kumar; Uma, K. N.; Konwar, M.; Ernest Raj, P.; Deshpande, S. M.; Kalapureddy, M. C. R.

2013-05-01

237

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

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

238

4-D display of satellite cloud images  

NASA Technical Reports Server (NTRS)

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

Hibbard, William L.

1987-01-01

239

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

240

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

241

Cloud layer thicknesses from a combination of surface and upper-air observations  

NASA Technical Reports Server (NTRS)

Cloud layer thicknesses are derived from base and top altitudes by combining 14 years (1975-1988) of surface and upper-air observations at 63 sites in the Northern Hemisphere. Rawinsonde observations are employed to determine the locations of cloud-layer top and base by testing for dewpoint temperature depressions below some threshold value. Surface observations serve as quality checks on the rawinsonde-determined cloud properties and provide cloud amount and cloud-type information. The dataset provides layer-cloud amount, cloud type, high, middle, or low height classes, cloud-top heights, base heights and layer thicknesses, covering a range of latitudes from 0 deg to 80 deg N. All data comes from land sites: 34 are located in continental interiors, 14 are near coasts, and 15 are on islands. The uncertainties in the derived cloud properties are discussed. For clouds classified by low-, mid-, and high-top altitudes, there are strong latitudinal and seasonal variations in the layer thickness only for high clouds. High-cloud layer thickness increases with latitude and exhibits different seasonal variations in different latitude zones: in summer, high-cloud layer thickness is a maximum in the Tropics but a minimum at high latitudes. For clouds classified into three types by base altitude or into six standard morphological types, latitudinal and seasonal variations in layer thickness are very small. The thickness of the clear surface layer decreases with latitude and reaches a summer minimum in the Tropics and summer maximum at higher latitudes over land, but does not vary much over the ocean. Tropical clouds occur in three base-altitude groups and the layer thickness of each group increases linearly with top altitude. Extratropical clouds exhibit two groups, one with layer thickness proportional to their cloud-top altitude and one with small (less than or equal to 1000 m) layer thickness independent of cloud-top altitude.

Poore, Kirk D.; Wang, Junhong; Rossow, William B.

1995-01-01

242

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

243

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

NASA Technical Reports Server (NTRS)

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

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

2013-01-01

244

Forecasting maximum wave height at selected sites based on high resolution hindcast modeling and local adaptation techniques  

NASA Astrophysics Data System (ADS)

Extreme wave heights play a major role in many deep offshore and coastal activities today. As a result, it is of significant importance to understand and accurately simulate their behavior. The lack of a dense in-situ and remote sensing observational network implies non trivial difficulties in this framework. A way out can be given by the utilization of high resolution third generation spectral wave models that incorporate advanced formulations for the estimation of maximum wave height conditions along with local adaptation techniques which can simulate in a credible way the non-frequent values for a specific area. For this study, a 10-year (2001-2010) hourly high resolution dataset of the main metocean parameters that covers the entire European coastline with a resolution of 5km, developed by the Atmospheric Modeling and Weather Forecasting Group of the National and Kapodistrian University of Athens in the framework of the FP7 project MARINA Platform (http://www.marina-platform.info/index.aspx) was utilized. The hindcast wave data, based on the latest version of the wave model WAM, in conjunction with non-conventional statistical methods and available buoy measurements for selected locations in the Spanish coastline formed an integrated system able to provide accurate maximum wave height estimations taking into consideration the climatological characteristics of the area.

Kalogeri, Christina; Galanis, George; Kallos, George

2014-05-01

245

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

246

Identity-based Encryption with Outsourced Revocation in Cloud Computing  

E-print Network

) which simplifies the public key and certificate management at Public Key Infrastructure (PKI well studied in traditional PKI setting, but the cumbersome management of certificates is precisely during key-issuing and key-update processes to a Key Update Cloud Service Provider, leaving only

Hou, Y. Thomas

247

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

248

Cloud Services Cloud Services  

E-print Network

Cloud Services Cloud Services In 2012 UCD IT Services launched an exciting new set of cloud solutions called CloudEdu, which includes cloud servers, cloud storage, cloud hosting and cloud network. The CloudEdu package includes a consultancy service in design, deployment, management and utilisation

249

Climatology of Warm Boundary Layer Clouds at the ARM SGP Site and Their Comparison to Models  

Microsoft Academic Search

A 4-yr climatology (1997 2000) of warm boundary layer cloud properties is developed for the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) Program Southern Great Plains (SGP) site. Parameters in the climatology include cloud liquid water path, cloud-base height, and surface solar flux. These parameters are retrieved from measurements produced by a dual-channel microwave radiometer, a millimeter-wave cloud radar,

Manajit Sengupta; Eugene E. Clothiaux; Thomas P. Ackerman

2004-01-01

250

The roughness height and drag law over the water surface based on the hypothesis of local equilibrium  

Microsoft Academic Search

A series of measurements of winds and wind-waves were carried out in wind-wave flumes. A data analysis based on the hypothesis\\u000a of local equilibrium yielded a new empirical formula on the controversial quantity of roughness heightz\\u000a 0 over the water surface:\\u000a $$\\\\tilde z_0 = 1.02 x 10^{ - 2} \\\\tilde u$$\\u000a , where the nondimensional roughness height\\u000a $$\\\\tilde z_0 $$

Tadao Kusaba; Akira Masuda

1988-01-01

251

Validity of Web-Based Self-Reported Weight and Height: Results of the Nutrinet-Sant? Study  

PubMed Central

Background With the growing scientific appeal of e-epidemiology, concerns arise regarding validity and reliability of Web-based self-reported data. Objective The objectives of the present study were to assess the validity of Web-based self-reported weight, height, and resulting body mass index (BMI) compared with standardized clinical measurements and to evaluate the concordance between Web-based self-reported anthropometrics and face-to-face declarations. Methods A total of 2513 participants of the NutriNet-Santé study in France completed a Web-based anthropometric questionnaire 3 days before a clinical examination (validation sample) of whom 815 participants also responded to a face-to-face anthropometric interview (concordance sample). Several indicators were computed to compare data: paired t test of the difference, intraclass correlation coefficient (ICC), and Bland–Altman limits of agreement for weight, height, and BMI as continuous variables; and kappa statistics and percent agreement for validity, sensitivity, and specificity of BMI categories (normal, overweight, obese). Results Compared with clinical data, validity was high with ICC ranging from 0.94 for height to 0.99 for weight. BMI classification was correct in 93% of cases; kappa was 0.89. Of 2513 participants, 23.5% were classified overweight (BMI?25) with Web-based self-report vs 25.7% with measured data, leading to a sensitivity of 88% and a specificity of 99%. For obesity, 9.1% vs 10.7% were classified obese (BMI?30), respectively, leading to sensitivity and specificity of 83% and 100%. However, the Web-based self-report exhibited slight underreporting of weight and overreporting of height leading to significant underreporting of BMI (P<.05) for both men and women: –0.32 kg/m2 (SD 0.66) and –0.34 kg/m2 (SD 1.67), respectively. Mean BMI underreporting was –0.16, –0.36, and –0.63 kg/m2 in the normal, overweight, and obese categories, respectively. Almost perfect agreement (ie, concordance) was observed between Web-based and face-to-face report (ICC ranged from 0.96 to 1.00, classification agreement was 98.5%, and kappa 0.97). Conclusions Web-based self-reported weight and height data from the NutriNet-Santé study can be considered as valid enough to be used when studying associations of nutritional factors with anthropometrics and health outcomes. Although self-reported anthropometrics are inherently prone to biases, the magnitude of such biases can be considered comparable to face-to-face interview. Web-based self-reported data appear to be an accurate and useful tool to assess anthropometric data. PMID:23928492

Peneau, Sandrine; Touvier, Mathilde; Julia, Chantal; Galan, Pilar; Hercberg, Serge; Kesse-Guyot, Emmanuelle

2013-01-01

252

Study on ecological impact evaluation for land consolidation based on cloud model: a case study of Miaotan town  

Microsoft Academic Search

Combining the basic theory of cloud model and the process of ecological impact evaluation for land consolidation, the author constructs the rule of ecological impact evaluation and the cloud models of the antecedent and the consequent, by translating the uncertain factor conditions into quantitative values with the uncertain illation based on cloud model, computes the evaluation factor scores and comprehensive

Yao-lin Liu; Min Fan; Xiao-yu Yang; Hui Liu

2008-01-01

253

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

NASA Technical Reports Server (NTRS)

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

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

1998-01-01

254

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

255

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

256

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

257

Using ground-based stereo cameras to derive cloud-level wind fields.  

PubMed

Upper-level wind fields are obtained by tracking the motion of cloud features as seen in calibrated ground-based stereo cameras. By tracking many cloud features, it is possible to obtain horizontal wind speed and direction over a cone area throughout the troposphere. Preliminary measurements were made at the Mauna Loa Observatory, and resulting wind measurements are compared with winds from the Hilo, Hawaii radiosondes. PMID:19684790

Porter, John N; Cao, Guang Xia

2009-08-15

258

3D Stochastic cloud generation for performance evaluation of space-based optical system  

Microsoft Academic Search

A three-dimensional (3D) stochastic cloud generation architecture is developed to simulate radiative scenes for performance evaluation of space-based optical system. The rescale-and-add fractal algorithm is employed to generate internal and external structure data of clouds. The Spherical Harmonic Discrete Ordinate (SHDOM) code is selected to solve the 3D radiative transfer equation numerically. The flowchart of the simulation system is shown.

Yiming Cao; Wei Zhang; Yin Zhang; Mingyu Cong; Hongbin Nie; Wenzhuo Bao

2010-01-01

259

Analysis of interstellar cloud structure based on IRAS images  

NASA Technical Reports Server (NTRS)

The goal of this project was to develop new tools for the analysis of the structure of densely sampled maps of interstellar star-forming regions. A particular emphasis was on the recognition and characterization of nested hierarchical structure and fractal irregularity, and their relation to the level of star formation activity. The panoramic IRAS images provided data with the required range in spatial scale, greater than a factor of 100, and in column density, greater than a factor of 50. In order to construct densely sampled column density maps of star-forming clouds, column density images of four nearby cloud complexes were constructed from IRAS data. The regions have various degrees of star formation activity, and most of them have probably not been affected much by the disruptive effects of young massive stars. The largest region, the Scorpius-Ophiuchus cloud complex, covers about 1000 square degrees (it was subdivided into a few smaller regions for analysis). Much of the work during the early part of the project focused on an 80 square degree region in the core of the Taurus complex, a well-studied region of low-mass star formation.

Scalo, John M.

1992-01-01

260

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

261

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

262

Chemical flame heights  

Microsoft Academic Search

A “chemical” flame height has been defined from the ratio of CO to CO2 yields, yCO\\/yCO2, and has been shown to be functionally identical with previous results based on flame luminosity. The chemical flame heights have been determined for propane and acetylene data for fire Froude numbers, Q*, ranging from 0.1 to 60,000. The functional dependence of Zf\\/D on Q*

Jeffrey S Newman; Christopher J Wieczorek

2004-01-01

263

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

264

Joint occurrence period of wind speed and wave height based on both service term and risk probability  

NASA Astrophysics Data System (ADS)

Return periods calculated for different environmental conditions are key parameters for ocean platform design. Many codes for offshore structure design give no consideration about the correlativity among multi-loads and over-estimate design values. This frequently leads to not only higher investment but also distortion of structural reliability analysis. The definition of design return period in existing codes and industry criteria in China are summarized. Then joint return periods of different ocean environmental parameters are determined from the view of service term and danger risk. Based on a bivariate equivalent maximum entropy distribution, joint design parameters are estimated for the concomitant wave height and wind speed at a site in the Bohai Sea. The calculated results show that even if the return period of each environmental factor, such as wave height or wind speed, is small, their combinations can lead to larger joint return periods. Proper design criteria for joint return period associated with concomitant environmental conditions will reduce structural size and lead to lower investment of ocean platforms for the exploitation of marginal oil field.

Dong, Sheng; Fan, Dunqiu; Tao, Shanshan

2012-12-01

265

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

NASA Technical Reports Server (NTRS)

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

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

1979-01-01

266

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

267

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

SciTech Connect

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

Porch, W.M.

1998-10-13

268

7, 1711717146, 2007 Dependence of cloud  

E-print Network

ACPD 7, 17117­17146, 2007 Dependence of cloud fraction and cloud height on temperature T. Wagner et a Creative Commons License. Atmospheric Chemistry and Physics Discussions Dependence of cloud fraction and cloud top height on surface temperature derived from spectrally resolved UV/vis satellite observations T

Paris-Sud XI, Université de

269

Comparison between ATSR-2 stereo, MOS O2-A band and ground-based cloud top heights  

E-print Network

, Room 678, New York, NY 10025, USA {now at Mail Stop 183-601, Jet Propulsion Laboratory, 4800 Oak Grove the visible, near-infrared and thermal infrared regions of the electromagnetic spectrum. The unique dual

270

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

271

Sources of uncertainties in satellite-based cloud droplet size retrieval: An integrated modeling and observational study  

NASA Astrophysics Data System (ADS)

Low-level warm marine boundary layer (MBL) clouds have a significant role in Earth's radiative energy balance and hydrological cycle. Yet, our understanding of their microphysical processes and relationships with environmental factors such as aerosol loading is still limited. Improving our understanding relies heavily on global continuous observation of MBL cloud properties from satellite sensors. A well-documented method to simultaneously retrieve cloud droplet size and cloud optical thickness is the so-called bi-spectral solar reflective method (Nakajima and King 1990). Several widely used satellite cloud products, including MODIS operational cloud product, is based on this method. Recently, we have systematically investigated the several major sources of uncertainty in the bi-spectral solar reflective method for MBL cloud droplet size retrieval, using both modeling and observational approaches. These uncertainty sources include 1) cloud microphysical vertical structure, 2) the shape of cloud droplet size distribution and 3) cloud horizontal heterogeneity and 3D radiative transfer effects. This work provides an overview of how these uncertainties affect cloud droplet size retrieval based on the bi-spectral solar reflective method and what are the potential implications

Zhang, Z.; Platnick, S. E.; Ackerman, A. S.; Pincus, R.; Lebsock, M. D.; Cho, H.

2013-12-01

272

Point Cloud Skeletons via Laplacian-Based Contraction Junjie Cao, Andrea Tagliasacchi, Matt Olson, Hao Zhang and Zhixun Su  

E-print Network

Point Cloud Skeletons via Laplacian-Based Contraction Junjie Cao, Andrea Tagliasacchi, Matt Olson skeleton extraction via Laplacian-based contraction. Our algorithm can be applied to surfaces, allowing skeleton-based manipulation of point clouds without explicit surface reconstruction. By avoiding

Zhang, Richard "Hao"

273

Clouds Roll in for Martian Winter  

NASA Technical Reports Server (NTRS)

Using its left navigation camera, the Mars Exploration Rover Opportunity sought to capture some clouds on its 153rd sol on Mars (June 28, 2004). The presence of morning clouds in the area of Endurance Crater was established by spacecraft orbiting Mars. Mars has three kinds of clouds: dust clouds low in the atmosphere; water clouds near the surface up to heights of 20 kilometers (about 12 miles); and carbon dioxide clouds at very high altitudes.

Just as on Earth, clouds, especially water clouds, are good tracers of the weather. Based on orbital data, more clouds are expected during the martian winter. As this change occurs, the rover's cameras and miniature thermal emission spectrometer will track other changes that occur as the clouds accumulate.

The rovers provide a unique opportunity to examine the lower portion of Mars' atmosphere. The lower atmosphere is difficult to characterize from orbit, but it is critical because that is where the atmosphere interacts with the surface. Since the rovers landed, the science team has been using the rover's miniature thermal emission spectrometer instrument to see the weather at this bottom layer.

2004-01-01

274

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

275

Continental liquid water cloud variability and its parameterization using Atmospheric Radiation Measurement data  

NASA Astrophysics Data System (ADS)

Liquid water path (LWP) variability at scales ranging from roughly 200 m to 20 km in continental boundary layer clouds is investigated using ground-based remote sensing at the Oklahoma site of the Atmospheric Radiation Measurement (ARM) program. Twelve episodes from the years of 1999 to 2001 are selected corresponding to conditions of overcast, liquid water single-layered cloud. In contrast to previous studies of marine boundary layer clouds, variability in cloud-top height in these clouds is comparable to that of cloud base, and most continental clouds appear to be subadiabatic. In agreement with previous studies of marine boundary layer clouds, variations in LWP are well related to the variations in cloud thickness. LWP variability exhibits significantly negative correlation with the static stability of the inversion near cloud top; larger cloud variability is associated with less stable inversions. A previously developed parameterization of LWP variability is extended to account for the differing conditions of continental clouds. The relationship between fluctuations in LWP and cloud thickness suggests that cloud parameterizations treating variations in LWP at these scales should include the effects of subgrid-scale fluctuations in cloud thickness. One such treatment is proposed within the context of a statistical cloud scheme.

Kim, Byung-Gon; Klein, Stephen A.; Norris, Joel R.

2005-08-01

276

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

PubMed

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

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

2014-01-01

277

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, Mairtin; Zhang, Xin; Zhang, Xueji

2014-01-01

278

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

279

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

280

InGaN-Based Light-Emitting Diodes Fabricated on Nano Patterned Sapphire Substrates with Pillar Height of More than 600 nm by Nanoimprint Lithography  

NASA Astrophysics Data System (ADS)

GaN-based light-emitting diodes (LEDs) were fabricated on nano patterned sapphire substrates (nano-PSSs) by nanoimprint (NIP) lithography. A nano-PSS with a pillar height of more than 600 nm was achieved. The surface emission of the LEDs was strongly affected by pillar height, and the surface emission intensity was highest at a pillar height of 250 nm. In contrast, the external quantum efficiency of the LEDs on the nano-PSSs with diameters of 100 and 450 nm was approximately 30% higher than that on a flat sapphire substrate, which is similar to that on a conventional PSS.

Okada, Narihito; Egami, Takuya; Miyoshi, Seita; Inomoto, Ryo; Yamane, Keisuke; Tadatomo, Kazuyuki; Nishimiya, Tomoyasu; Hiramoto, Michihiro; Motoyama, Shin-ichi

2013-11-01

281

Solar coupling to clouds through the global electric circuit  

NASA Astrophysics Data System (ADS)

Earth's global electric circuit extends from the planet's surface to the Ionosphere, coupling the two regions by permitting vertical current flow. The upper and lower horizontal edges of non-thunderstorm layer clouds acquire charge as a consequence of this current flow, due to the sharp vertical gradient in electrical conductivity that exists between the cloud and clear air regions. Such cloud edge charging results in electrification of cloud droplets, which can influence some cloud microphysical processes and potentially provides one source of variability in the macroscopic properties of clouds. Above the Earth's surface, the atmosphere's electrical conductivity is mainly from ionisation due to Galactic Cosmic Rays (GCRs), which vary with solar activity on many different timescales. Solar modulation of GCRs allows the global electric circuit to convey a solar influence to the lower atmosphere, and, potentially to some meteorological phenomena through modulation of cloud properties through electrified cloud edges. Evidence for a microphysical response to the global circuit at a horizontal cloud boundary is supported by the presence of a diurnal oscillation in the height of the cloud base in the both the Arctic and Antarctic during polar night, which is similar in phase to that of the Carnegie curve in global atmospheric electricity. In order to improve knowledge of possible atmospheric electrical effects on layer clouds, a campaign of experiments with new instrumentation has been undertaken, taking advantage of in-situ measurements. These have been made from a free balloon platform, using specially developed disposable instrumentation capable of measuring charge and optical cloud properties inside non-thunderstorm clouds. The combined sensor package monitors the cloud and electrical properties simultaneously, using a solar radiation sensor, cloud droplet sensor and a charge sensor, providing a new approach to obtaining high vertical resolution measurements of cloud boundaries. These measurements will be discussed in terms of the typical distribution of charge present in layer clouds, and the potential implications of the charging observed on cloud microphysical processes.

Nicoll, K.; Harrison, R.

2013-12-01

282

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

283

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

284

Global model of the F2 layer peak height for low solar activity based on GPS radio-occultation data  

NASA Astrophysics Data System (ADS)

We propose a global median model SMF2 (Satellite Model of the F2 layer) of the ionospheric F2-layer height maximum (hmF2), based on GPS radio-occultation data for low solar activity periods (F10.7A<80). The model utilizes data provided by GPS receivers onboard satellites CHAMP (~100,000 hmF2 values), GRACE (~70,000) and COSMIC (~2,000,000). The data were preprocessed to remove cases where the absolute maximum of the electron density lies outside the F2 region. Ground-based ionospheric sounding data were used for comparison and validation. Spatial dependence of hmF2 is modeled by a Legendre-function expansion. Temporal dependence, as a function of Universal Time (UT), is described by a Fourier expansion. Inputs of the model are: geographical coordinates, month and F10.7A solar activity index. The model is designed for quiet geomagnetic conditions (K?=1-2), typical for low solar activity.

Shubin, V. N.; Karpachev, A. T.; Tsybulya, K. G.

2013-11-01

285

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

286

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

287

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 found between all CTHs from MSG (CLA box and AMV) and CALIOP. However, the AMV pressure allocation of the HA methods to several atmospheric parameters. Meteosat Second Generation (MSG) provides many new

Madeleine, Jean-Baptiste

288

GROUND-BASED CLOUD IMAGES AND SKY RADIANCES IN THE VISIBLE AND NEAR INFRARED REGION FROM  

E-print Network

GROUND-BASED CLOUD IMAGES AND SKY RADIANCES IN THE VISIBLE AND NEAR INFRARED REGION FROM WHOLE SKY and near infrared # uwe.feister@dwd.de #12;region was developed at UCSD upon requests of the German Weather reliably with one interruption to correct align- ment of the filter wheels. Some general features

Shields, Janet

289

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 spectrum bands are extremely under-utilized. Experimental tests in academia [4], [5] and measurements networks (CRNs) and promoted a lot of interesting research on the design of spectrum trading systems [8

Latchman, Haniph A.

290

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

E-print Network

Robust Message-Privacy Preserving Image Copy Detection for Cloud-based Systems M. Diephuis, S--In this paper we propose an architecture for message-privacy preserving copy detection and content identi. The architecture allows for search- ing in encrypted data and places the computational burden on the server. Sign

Genève, Université de

291

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

292

Predictive Data Grouping and Placement for Cloud-based Elastic Server Infrastructures  

E-print Network

opportunity to approach this problem, by developing elastic large scale server infrastructures. However, energy, administration and maintenance costs. One of the main concerns of Web service providersPredictive Data Grouping and Placement for Cloud-based Elastic Server Infrastructures Juan M

Isaila, Florin

293

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

294

A new retrieval for cloud liquid water path using a ground-based microwave radiometer and measurements of cloud temperature  

Microsoft Academic Search

A new method to retrieve cloud liquid water path using 23.8 and 31.4 GHz microwave radiometer brightness temperature measurements is developed. This method does not depend on climatological estimates of either the mean radiating temperature of the atmosphere Tmr or the mean cloud liquid water temperature Tcloud. Rather, Tmr is estimated from surface temperature and relative humidity measurements, while Tcloud

James C. Liljegren; Eugene E. Clothiaux; Gerald G. Mace; Seiji Kato; Xiquan Dong

2001-01-01

295

The Evaluation of CloudSat and CALIPSO Ice Microphysical Products Using Ground-Based Cloud Radar and Lidar Observations  

E-print Network

by a large positive bias of 8­12 mm. A sensitivity test shows that in response to such a bias the cloud are suggested in this study. Effective radii retrievals from the standard CloudSat algorithms are characterized longwave forcing is increased from 44.6 to 46.9 W m22 (implying an error of about 5%), whereas the negative

Protat, Alain

296

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

297

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

Microsoft Academic Search

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

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

2012-01-01

298

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

Microsoft Academic Search

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

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

2011-01-01

299

Dual-FOV Raman and Doppler lidar studies of aerosol-cloud interactions: Simultaneous profiling of aerosols, warm-cloud properties, and vertical wind  

NASA Astrophysics Data System (ADS)

For the first time, colocated dual-field of view (dual-FOV) Raman lidar and Doppler lidar observations (case studies) of aerosol and cloud optical and microphysical properties below and within thin layered liquid water clouds are presented together with an updraft and downdraft characterization at cloud base. The goal of this work is to investigate the relationship between aerosol load close to cloud base and cloud characteristics of warm (purely liquid) clouds and the study of the influence of vertical motions and turbulent mixing on this relationship. We further use this opportunity to illustrate the applicability of the novel dual-FOV Raman lidar in this field of research. The dual-FOV lidar combines the well-established multiwavelength Raman lidar technique for aerosol retrievals and the multiple-scattering Raman lidar technique for profiling of the single-scattering extinction coefficient, effective radius, number concentration of the cloud droplets, and liquid water content. Key findings of our 3 year observations are presented in several case studies of optically thin altocumulus layers occurring in the lower free troposphere between 2.5 and 4 km height over Leipzig, Germany, during clean and polluted situations. For the clouds that we observed, the most direct link between aerosol proxy (particle extinction coefficient) and cloud proxy (cloud droplet number concentration) was found at cloud base during updraft periods. Above cloud base, additional processes resulting from turbulent mixing and entrainment of dry air make it difficult to determine the direct impact of aerosols on cloud processes.

Schmidt, Jörg; Ansmann, Albert; Bühl, Johannes; Baars, Holger; Wandinger, Ulla; Müller, Detlef; Malinka, Aleksey V.

2014-05-01

300

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

301

Cloud and precipitation properties from ground-based remote sensing instruments in East Antarctica  

NASA Astrophysics Data System (ADS)

A new comprehensive cloud-precipitation-meteorological observatory has been established at Princess Elisabeth base, located in the escarpment zone of Dronning Maud Land, East Antarctica. The observatory consists of a set of ground-based remote sensing instruments (ceilometer, infrared pyrometer and vertically profiling precipitation radar) combined with automatic weather station measurements of near-surface meteorology, radiative fluxes, and snow accumulation. In this paper, the observatory is presented and the potential for studying the evolution of clouds and precipitating systems is illustrated by case studies. It is shown that the synergetic use of the set of instruments allows for distinguishing ice, mixed-phase and precipitating clouds, including some information on their vertical extent. In addition, wind-driven blowing snow events can be distinguished from deeper precipitating systems. Cloud properties largely affect the surface radiative fluxes, with liquid-containing clouds dominating the radiative impact. A statistical analysis of all measurements (in total 14 months mainly occurring in summer/autumn) indicates that these liquid-containing clouds occur during as much as 20% of the cloudy periods. The cloud occurrence shows a strong bimodal distribution with clear sky conditions 51% of the time and complete overcast conditions 35% of the time. Snowfall occurred 17% of the cloudy periods with a predominance of light precipitation and only rare events with snowfall > 1 mm h-1 water equivalent (w.e.). Three of such intensive snowfall events occurred during 2011 contributing to anomalously large annual snow accumulation. This is the first deployment of a precipitation radar in Antarctica allowing to assess the contribution of the snowfall to the local surface mass balance. It is shown that on the one hand large accumulation events (>10 mm w.e. day-1) during the measurement period of 26 months were always associated with snowfall, but that on the other hand snowfall did not always lead to accumulation. In general, this promising set of robust instrumentation allows for improved insight in cloud and precipitation processes in Antarctica and can be easily deployed at other Antarctic stations.

Gorodetskaya, I. V.; Kneifel, S.; Schween, J. H.; Crewell, S.; Van Lipzig, N. P. M.

2014-07-01

302

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

303

CalNex cloud properties retrieved from a ship-based spectrometer and comparisons with satellite and aircraft retrieved cloud properties  

NASA Astrophysics Data System (ADS)

An algorithm to retrieve cloud optical thickness and effective radius (reff) from spectral transmittance was applied to radiance and irradiance observations of the Solar Spectral Flux Radiometer (SSFR) during the Research at the Nexus of Air Quality and Climate Change Campaign (CalNex). Data from an overcast day, 16 May 2010, was used to validate the algorithm. Retrievals from the SSFR, deployed on the Woods Hole Oceanic Institute R/V Atlantis, were compared to retrievals made from an airborne SSFR, the Geostationary Operations Environmental Satellite (GOES), an Atlantis-based microwave radiometer, and the Moderate Resolution Imaging Spectroradiometer. In situ observations of reff during a flight over the Atlantis were compared to the Atlantis SSFR and GOES retrievals. The cloud statistics for the CalNex campaign were compared to previous studies. The agreement between the different retrievals, quantified by determining the number of coincident observations when retrieval uncertainty overlapped, improved as the difference between the field-of-views (FOV) of the instruments decreased. It is shown that averaging the 1 Hz SSFR observations to the 15 minute GOES interval cannot fully account for the impact of the different FOVs. The average in situ reff (7.7 ?m) fell between the average reff retrieved using the Atlantis-based SSFR radiance (5.7 ?m) and irradiance (9.5 ?m). The CalNex clouds showed a diurnal pattern observed in previous studies of marine boundary layer clouds in the region. The distribution of cloud optical thickness and liquid water path during CalNex was shown to be a gamma distribution, consistent with previous studies of high cloud fraction marine boundary layer clouds.

McBride, P. J.; Schmidt, K. S.; Pilewskie, P.; Walther, A.; Heidinger, A. K.; Wolfe, D. E.; Fairall, C. W.; Lance, S.

2012-10-01

304

Compute unified device architecture (CUDA)-based parallelization of WRF Kessler cloud microphysics scheme  

NASA Astrophysics Data System (ADS)

In recent years, graphics processing units (GPUs) have emerged as a low-cost, low-power and a very high performance alternative to conventional central processing units (CPUs). The latest GPUs offer a speedup of two-to-three orders of magnitude over CPU for various science and engineering applications. The Weather Research and Forecasting (WRF) model is the latest-generation numerical weather prediction model. It has been designed to serve both operational forecasting and atmospheric research needs. It proves useful for a broad spectrum of applications for domain scales ranging from meters to hundreds of kilometers. WRF computes an approximate solution to the differential equations which govern the air motion of the whole atmosphere. Kessler microphysics module in WRF is a simple warm cloud scheme that includes water vapor, cloud water and rain. Microphysics processes which are modeled are rain production, fall and evaporation. The accretion and auto-conversion of cloud water processes are also included along with the production of cloud water from condensation. In this paper, we develop an efficient WRF Kessler microphysics scheme which runs on Graphics Processing Units (GPUs) using the NVIDIA Compute Unified Device Architecture (CUDA). The GPU-based implementation of Kessler microphysics scheme achieves a significant speedup of 70× over its CPU based single-threaded counterpart. When a 4 GPU system is used, we achieve an overall speedup of 132× as compared to the single thread CPU version.

Mielikainen, Jarno; Huang, Bormin; Wang, Jun; Allen Huang, H.-L.; Goldberg, Mitchell D.

2013-03-01

305

Dynamic Request Management Algorithms for Web-Based Services in Cloud Computing  

Microsoft Academic Search

Providers of Web-based services can take advantage of many convenient features of cloud computing infrastructures, but they still have to implement request management algorithms that are able to face sudden peaks of requests. We consider distributed algorithms implemented by front-end servers to dis- patch and redirect requests among application servers. Current solutions based on load-blind algorithms, or considering just server

Riccardo Lancellotti; Mauro Andreolini; Claudia Canali; Michele Colajanni

2011-01-01

306

Web based RFID Asset Management Solution established on Cloud Services  

E-print Network

supported by a web based user interface, eliminating the role of the former. Such an interface allows a user remotely. Load testing was carried out to test the processing capability of the RFID reader based Reader, is not tied to any programming language or operating system and uses a standardized XML (Extensible Markup

California at Los Angeles, University of

307

A Cloud-Based Scheme for Protecting Source-Location Privacy against Hotspot-Locating Attack in Wireless  

E-print Network

1 A Cloud-Based Scheme for Protecting Source-Location Privacy against Hotspot-Locating Attack for efficiently pro- tecting source nodes' location privacy against Hotspot- Locating attack by creating a cloud of fake packets and also boost privacy preservation. Simulation and analyti- cal results demonstrate

Shen, Xuemin "Sherman"

308

The accuracy of water vapor and cloud liquid determination by dual-frequency ground-based microwave radiometry  

Microsoft Academic Search

A dual frequency ground-based radiometer operating in the 1 to 1.4 cm wavelength range can provide continuous measurements of integrated water vapor and cloud liquid water. Using climato- logical data, the accuracy of the vapor and liquid determinations is estimated as a function of cloud amount. Limiting factors in the water determination are uncertainties in water vapor absorption coefficients and,

Ed R. Westwater

1978-01-01

309

Estimations of Cloud Optical Thickness from Ground-Based Measurements of Incoming Solar Radiation in the Arctic  

Microsoft Academic Search

A technique for evaluation of cloud optical thickness (plant-parallel, homogeneous layer) from ground-based measurements of incoming solar irradiance using a simple radiation model is introduced. The sensitivities of downward and upward fluxes of shortwave irradiance to surface albedo and the equivalent radius of cloud drops are analyzed. We show that the incoming solar irradiance at the surface during overcast conditions

E. Leontyeva; K. Stamnes

1994-01-01

310

Arctic mixed-phase summer clouds: Lessons from ASCOS  

NASA Astrophysics Data System (ADS)

As part of the 2007-2009 International Polar Year, the 2008 Arctic Summer Cloud and Ocean Study (ASCOS) experiment gathered detailed observations of the autumn central Arctic troposphere, boundary layer and surface energy budget, with an emphasis on how mixed-phase clouds impact the system. This presentation provides an overview of results from ASCOS examining the interactions between thermodynamics, boundary layer structure and dynamic motions generated within mixed-phase clouds. Over the Arctic Ocean, mixed-phase clouds in the lower troposphere occur frequently. These clouds exert the largest, most critical component on the surface energy budget via interactions with radiative fluxes. The surface cloud-radiative effect has the potential to control the sign and magnitude of the surface energy residual (positive - melting, or negative - freezing) and the boundary layer stability. Despite a common near-neutrally stratified boundary layer up to below ~ 500 m, mixed-phase clouds were most frequently found to be decoupled from the surface. Cloud-generated vertical motions produced via radiative divergence near cloud top produce mixing across the cloud layer and into the sub-cloud layer. The extent at which these motions couple with the surface mixed-layer correlates positively with liquid water path, cloud base height and cloud thickness; all of these factors affect the strength of vertical motions produced by the cloud layer. Persistence of the cloud is attributed to moisture inversions co-located with temperature inversions, often characterizing the upper third of the cloud layers. In-cloud vertical velocity characteristics derived from cloud radar shows a unique vertical structure that corresponds with the thermodynamic structure within the cloud. Despite cloud penetration within the stable, yet moist, temperature inversion, we show that peak cloud-generated vertical velocity overturning time scales are surprisingly similar and coherent across three levels within cloud; additionally velocity overturning time scales are similar regardless of coupling between the cloud-surface system. These findings help to better understand the resilience of Arctic mixed-phase clouds.

Tjernström, Michael; Sedlar, Joseph; Brooks, Ian; Persson, Ola; Shupe, Matthew

2014-05-01

311

On the optimal method for evaluating cloud products from passive satellite imagery using CALIPSO-CALIOP data: example investigating the CM SAF CLARA-A1 dataset  

NASA Astrophysics Data System (ADS)

A method for detailed evaluation of a new satellite-derived global 28 yr cloud and radiation climatology (Climate Monitoring SAF Clouds, Albedo and Radiation from AVHRR data, named CLARA-A1) from polar-orbiting NOAA and Metop satellites is presented. The method combines 1 km and 5 km resolution cloud datasets from the CALIPSO-CALIOP (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation - Cloud-Aerosol Lidar with Orthogonal Polarization) cloud lidar for estimating cloud detection limitations and the accuracy of cloud top height estimations. Cloud detection is shown to work efficiently for clouds with optical thicknesses above 0.30 except for at twilight conditions when this value increases to 0.45. Some misclassifications of cloud-free surfaces during daytime were revealed for semi-arid land areas in the sub-tropical and tropical regions leading to up to 20% overestimated cloud amounts. In addition, a substantial fraction (at least 20-30%) of all clouds remains undetected in the polar regions during the polar winter season due to the lack of or an inverted temperature contrast between Earth surfaces and clouds. Subsequent cloud top height evaluation took into account the derived information about the cloud detection limits. It was shown that this has fundamental importance for the achieved results. An overall bias of -274 m was achieved compared to a bias of -2762 m when no measures were taken to compensate for cloud detection limitations. Despite this improvement it was concluded that high-level clouds still suffer from substantial height underestimations, while the opposite is true for low-level (boundary layer) clouds. The validation method and the specifically collected satellite dataset with optimal matching in time and space are suggested for a wider use in the future for evaluation of other cloud retrieval methods based on passive satellite imagery.

Karlsson, K.-G.; Johansson, E.

2013-05-01

312

A High Performance Cloud-Based Protein-Ligand Docking Prediction Algorithm  

PubMed Central

The potential of predicting druggability for a particular disease by integrating biological and computer science technologies has witnessed success in recent years. Although the computer science technologies can be used to reduce the costs of the pharmaceutical research, the computation time of the structure-based protein-ligand docking prediction is still unsatisfied until now. Hence, in this paper, a novel docking prediction algorithm, named fast cloud-based protein-ligand docking prediction algorithm (FCPLDPA), is presented to accelerate the docking prediction algorithm. The proposed algorithm works by leveraging two high-performance operators: (1) the novel migration (information exchange) operator is designed specially for cloud-based environments to reduce the computation time; (2) the efficient operator is aimed at filtering out the worst search directions. Our simulation results illustrate that the proposed method outperforms the other docking algorithms compared in this paper in terms of both the computation time and the quality of the end result. PMID:23762864

Chen, Jui-Le; Yang, Chu-Sing

2013-01-01

313

2.5D multi-view gait recognition based on point cloud registration.  

PubMed

This paper presents a method for modeling a 2.5-dimensional (2.5D) human body and extracting the gait features for identifying the human subject. To achieve view-invariant gait recognition, a multi-view synthesizing method based on point cloud registration (MVSM) to generate multi-view training galleries is proposed. The concept of a density and curvature-based Color Gait Curvature Image is introduced to map 2.5D data onto a 2D space to enable data dimension reduction by discrete cosine transform and 2D principle component analysis. Gait recognition is achieved via a 2.5D view-invariant gait recognition method based on point cloud registration. Experimental results on the in-house database captured by a Microsoft Kinect camera show a significant performance gain when using MVSM. PMID:24686727

Tang, Jin; Luo, Jian; Tjahjadi, Tardi; Gao, Yan

2014-01-01

314

2.5D Multi-View Gait Recognition Based on Point Cloud Registration  

PubMed Central

This paper presents a method for modeling a 2.5-dimensional (2.5D) human body and extracting the gait features for identifying the human subject. To achieve view-invariant gait recognition, a multi-view synthesizing method based on point cloud registration (MVSM) to generate multi-view training galleries is proposed. The concept of a density and curvature-based Color Gait Curvature Image is introduced to map 2.5D data onto a 2D space to enable data dimension reduction by discrete cosine transform and 2D principle component analysis. Gait recognition is achieved via a 2.5D view-invariant gait recognition method based on point cloud registration. Experimental results on the in-house database captured by a Microsoft Kinect camera show a significant performance gain when using MVSM. PMID:24686727

Tang, Jin; Luo, Jian; Tjahjadi, Tardi; Gao, Yan

2014-01-01

315

Past, present and future vegetation-cloud feedbacks in the Amazon Basin  

Microsoft Academic Search

To begin exploring the underlying mechanisms that couple vegetation to cloud formation processes, we derive the lifting condensation\\u000a level (LCL) to estimate cumulus cloud base height. Using a fully coupled land–ocean–atmosphere general circulation model (HadCM3LC),\\u000a we investigate Amazonian forest feedbacks on cloud formation over three geological periods; modern-day (a.d. 1970–1990), the last glacial maximum (LGM; 21 kya), and under a future

E. Pinto; Y. Shin; S. A. Cowling; C. D. Jones

2009-01-01

316

The Roles of Cloud Drop Effective Radius and LWP in Determining Rain Properties in Marine Stratocumulus  

SciTech Connect

Numerical simulations described in previous studies showed that adding cloud condensation nuclei to marine stratocumulus can prevent their breakup from closed into open cells. Additional analyses of the same simulations show that the suppression of rain is well described in terms of cloud drop effective radius (re). Rain is initiated when re near cloud top is around 12-14 um. Cloud water starts to get depleted when column-maximum rain intensity (Rmax) exceeds 0.1 mm h-1. This happens when cloud-top re reaches 14 um. Rmax is mostly less than 0.1 mm h-1 at re<14 um, regardless of the cloud water path, but increases rapidly when re exceeds 14 um. This is in agreement with recent aircraft observations and theoretical observations in convective clouds so that the mechanism is not limited to describing marine stratocumulus. These results support the hypothesis that the onset of significant precipitation is determined by the number of nucleated cloud drops and the height (H) above cloud base within the cloud that is required for cloud drops to reach re of 14 um. In turn, this can explain the conditions for initiation of significant drizzle and opening of closed cells providing the basis for a simple parameterization for GCMs that unifies the representation of both precipitating and non-precipitating clouds as well as the transition between them. Furthermore, satellite global observations of cloud depth (from base to top), and cloud top re can be used to derive and validate this parameterization.

Rosenfeld, Daniel; Wang, Hailong; Rasch, Philip J.

2012-07-04

317

Ship-based remote sensing observations of clouds and aerosol over the Atlantic Ocean  

NASA Astrophysics Data System (ADS)

Within the framework of the OCEANET project, ship-based remote sensing observations of the atmosphere above the Atlantic Ocean have been performed on board of the German research vessels Polarstern and Meteor. Since 2007, twelve cruises took place, mostly between Bremerhaven (Germany) and Cape Town (South Africa) or Punta Arenas (Chile), respectively. In 2014 and 2015, two additional cruises will be performed. The goal of these ship-based measurements is a better understanding of water vapor, cloud and aerosol interaction over the open sea where data are scarce. The project was designed to measure the full atmospheric energy budget in different climate zones, including exchange processes at the sea surface. The main instrumentation on all cruises consisted of a passive microwave radiometer, a full sky imager, sun photometer, lidar ceilometer and broadband solar and infrared radiation measurements. In addition a multi wavelength Raman lidar (PollyXT) was on board of six cruises. Spectral solar radiance and irradiance observations have been performed on four cruises. With this dataset, a variety of topics can be addressed. This presentation will focus on marine stratocumulus clouds which are widespread over oceans and still pose a large uncertainty for determining the Earth's energy budget. Detailed studies for the northern trade wind zone off the West African coast will be presented. The emphasis lies on stratocumulus cloud properties, such as frequency, size, variability, liquid water content as well as their impact on surface radiation. Additionally, the influence of Saharan dust on the cloud occurrence will be addressed. Dust outbreaks over the ship could be observed in several years, including also at a cruise from the Caribbean Sea to Cape Verde in 2013. Furthermore, we will give a statistical overview of the meridional distribution of atmospheric water vapour and clouds over the Atlantic Ocean. With six years of measurements, always at the same time of the year, the variability of the atmospheric conditions in subtropical and tropical regions can be quantified.

Pospichal, Bernhard; Wolf, Veronika; Pietsch, Alexandra; Engelmann, Ronny; Macke, Andreas

2014-05-01

318

Urban air pollution modelling and measurements of boundary layer height  

NASA Astrophysics Data System (ADS)

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 week period in July 2003. In this work, the daily growth and decay of the BLH from the lidar data and model simulations for 5 days are compared. The results show that although the UM can do a good job of reproducing the boundary layer growth, there are occasions where the BLH is overestimated by 30-100%. Within dispersion models it is the BLH that effectively limits the height to which pollution disperses, so these results have very important implications for pollution dispersion modelling. The results show that correct development of the boundary layer in the UM is critically dependant on morning cloud cover. The ADMS model is used routinely by local authorities in the UK for local air-quality forecasting. The ADMS model was run under three settings; an 'urban' roughness, a 'rural' roughness and a 'transition' roughness. In all cases, the 'urban' setting over estimated the BLH and is clearly a poor predictor of urban BLH. The 'transition' setting, which distinguishes between the meteorological data input site and the dispersion modelling site, gave the best results under the well mixed conditions of the trial.

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

319

CMNIIACA: cloud model and niche-ideology-based improved ant colony algorithm  

NASA Astrophysics Data System (ADS)

In order to improve the convergence properties of basic ant colony algorithm (ACA), a novel type of Cloud Model and Niche Ideology-based Improved Ant Colony Algorithm (CMNIIACA) for solving complex combinational optimization problems is proposed in this paper. Cloud model theory is a powerful tool to convert numerical quantitative analysis to conceptual qualitative analysis. On the basis of introduction of ACA and cloud model theory, a novel qualitative strategy for improving the global optimization properties by use of cloud models is presented in this paper. Then, in order to avoid the stagnation, and to avoid local minima, pseudo-random-proportional action choice rule and elitist preservation strategy are adopted. As the inferior solutions seriously interfered with the searching quality, and inspired by the idea of ecological niche, all the discrete nodes are divided into several groups, the moving scope of each ant agent is then limited. Furthermore, we also limit the trail amount in a maximum-minimum interval. The simulation experiments on CHC150TSP have been performed. The computational results show that the proposed CMNIIACA can effectively improve the global convergence and the evolutional speed of ACA, and the stability of algorithm is also improved effectively. It is obvious that the CMNIIACA presented in this paper is efficient and outperforms ACA.

Duan, Haibin; Wang, Daobo; Yu, Xiufen

2006-11-01

320

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

321

Clouds Influence Precision and Accuracy of Ground?Based Spectroradiometers  

Microsoft Academic Search

The objectives of this study were to determine the precision and accuracy, under field conditions, of two commonly used ground?based spectroradiometers and to propose guidance on how to minimize system errors. Sunlight irradiance and reflected radiance were measured on calibration tarps (3.6% and 52% reflectance) on 6 days using a CropScan MSR 16 handheld multispectral radiometer and a Fieldspec model

Jiyul Chang; Sharon A. Clay; David E. Clay; David Aaron; Dennis Helder; Kevin Dalsted

2005-01-01

322

Geo-spatial Service and Application based on National E-government Network Platform and Cloud  

NASA Astrophysics Data System (ADS)

With the acceleration of China's informatization process, our party and government take a substantive stride in advancing development and application of digital technology, which promotes the evolution of e-government and its informatization. Meanwhile, as a service mode based on innovative resources, cloud computing may connect huge pools together to provide a variety of IT services, and has become one relatively mature technical pattern with further studies and massive practical applications. Based on cloud computing technology and national e-government network platform, "National Natural Resources and Geospatial Database (NRGD)" project integrated and transformed natural resources and geospatial information dispersed in various sectors and regions, established logically unified and physically dispersed fundamental database and developed national integrated information database system supporting main e-government applications. Cross-sector e-government applications and services are realized to provide long-term, stable and standardized natural resources and geospatial fundamental information products and services for national egovernment and public users.

Meng, X.; Deng, Y.; Li, H.; Yao, L.; Shi, J.

2014-04-01

323

Constraining CloudSat-based snowfall profiles using surface observations and C-band ground radar  

NASA Astrophysics Data System (ADS)

The CloudSat Precipitation Radar, launched in 2006, provides vertical profiles of W-band (94 GHz) reflectivity and is sensitive to falling snow through all but the most intense precipitating cloud structures. Precipitation retrievals of falling snow are affected by a wide diversity of factors describing the medium, such as snow particle shape, size, and composition, which in turn are controlled by ambient factors including the environmental temperature and humidity. Because satellite-based radiometric sounders such as the Microwave Humidity Sounder (MHS) operate without the benefit of coordinated space radar observations, microphysical descriptions of the snow particle medium derived from CloudSat or other radar observations are beneficial to passive microwave (PMW) radiometer-only snowfall retrieval methods. At the coarse scale of these PMW observations, the radiative signal due to the snow is relatively weak compared to the contributions from the atmosphere and the land surface emissivity. Using the C-band (5 GHz) polarization-agile King City radar (WKR) operated by Environment Canada, we examined the vertical structure of winter precipitation events from coordinated overpasses of CloudSat and NOAA 18 (MHS). Two-dimensional video disdrometer observations are used to limit (constrain) the range of the drop-size distribution parameters that are provided through a priori databases to dual-frequency (C/W-band) radar retrieval. Bayesian retrievals using the constrained database produce water content profiles that more closely replicate the observed radar reflectivity profiles and transition smoothly between the single-frequency (CloudSat only) and dual-frequency regions.

Turk, F. Joseph; Park, Kyung-Won; Haddad, Ziad S.; Rodriguez, Peter; Hudak, David R.

2011-12-01

324

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

325

Virtual Machine Scalability on Multi-Core Processors Based Servers for Cloud Computing Workloads  

Microsoft Academic Search

In this paper, we analyze virtual machine (VM) scalability on multi-core systems for compute-, memory-, and network I\\/O-intensive workloads. The VM scalability evaluation under these three workloads will help cloud users to understand the performance impact of underlying system and network architectures. We demonstrate that VMs on the state-of-the-art multi-core processor based systems scale as well as multiple threads on

Muhammad Hasan Jamal; Abdul Qadeer; Waqar Mahmood; Abdul Waheed; Jianxun Jason Ding

2009-01-01

326

NASA-Langley Web-Based Operational Real-time Cloud Retrieval Products from Geostationary Satellites  

NASA Technical Reports Server (NTRS)

At NASA Langley Research Center (LaRC), radiances from multiple satellites are analyzed in near real-time to produce cloud products over many regions on the globe. These data are valuable for many applications such as diagnosing aircraft icing conditions and model validation and assimilation. This paper presents an overview of the multiple products available, summarizes the content of the online database, and details web-based satellite browsers and tools to access satellite imagery and products.

Palikonda, Rabindra; Minnis, Patrick; Spangenberg, Douglas A.; Khaiyer, Mandana M.; Nordeen, Michele L.; Ayers, Jeffrey K.; Nguyen, Louis; Yi, Yuhong; Chan, P. K.; Trepte, Qing Z.; Chang, Fu-Lung; Smith, William L, Jr.

2006-01-01

327

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

Microsoft Academic Search

A technique is developed to model radiative transfer in three-dimensional natural clouds with a standard discrete ordinates finite-element method modified to evaluate cell-surface-averaged radiances. A log-least-squares-based scale transformation is used to improve the discrete phase-function model. We handle dense media by assuming constant diffuse radiances over input faces to cubic cells, allowing analytical forms for transmittance factors. Transmission equations are

David H. Tofsted; Sean G. O'Brien

1998-01-01

328

Implementation of MapReduce-based image conversion module in cloud computing environment  

Microsoft Academic Search

In recent years, the rapid advancement of the Internet and the growing number of people using social networking services (SNSs) have facilitated the sharing of multimedia data. However, multimedia data processing techniques such as transcoding and transmoding impose a considerable burden on the computing infrastructure as the amount of data increases. Therefore, we propose a MapReduce-based image-conversion module in cloud

Hyeokju Lee; Myoungjin Kim; Joon Her; Hanku Lee

2012-01-01

329

Web-based interactive visualization of PS-InSAR point clouds for education and training  

NASA Astrophysics Data System (ADS)

In radar remote sensing education and training, only few people have a good knowledge of radar remote sensing and geology, which would be necessary fully analyse the surface motions estimated by persistent scatterer interferometry. Using scientific visualization, data can be presented in an intuitive way for surface motion analysis of non-radar experts. In this paper, we introduce a web-based interactive visualization of PS-InSAR point clouds for education and training.

Liang, D.; Balz, T.; Wang, Z. Y.; Wei, L. H.; Liao, M. S.

2014-04-01

330

Cloud properties derived from two lidars over the ARM SGP site  

NASA Astrophysics Data System (ADS)

Active remote sensors such as lidars or radars can be used with other data to quantify the cloud properties at regional scale and at global scale. Relative to radar, lidar remote sensing is sensitive to very thin and high clouds but has a significant limitation due to signal attenuation in the ability to precisely quantify the properties of clouds with a cloud optical thickness larger than 3. The cloud properties for all levels of clouds are derived and distributions of cloud base height (CBH), top height (CTH), physical cloud thickness (CT), and optical thickness (COT) from local statistics are compared. The goal of this study is (1) to establish a climatology of macrophysical and optical properties for all levels of clouds observed over the ARM SGP site and (2) to estimate the discrepancies between the two remote sensing systems (pulse energy, sampling, resolution, etc.). Our first results tend to show that the MPL, which are the primary ARM lidars, have a distinctly limited range within which all of these cloud properties are detectable, especially cloud top and cloud thickness, but this can include cloud base particularly during summer daytime period. According to the comparisons between RL and MPL, almost 50% of situations show a signal to noise ratio too low (smaller than 3) for the MPL in order to detect clouds higher than 7km during daytime period in summer. Consequently, the MPL-derived annual cycle of cirrus cloud base (top) altitude is biased low, especially for daylight periods, compared with those derived from the RL data, which detects cloud base ranging from 7.5 km in winter to 9.5 km in summer (and tops ranging from 8.6 to 10.5 km). The optically thickest cirrus clouds (COT > 0.3) reach 50% of the total population for the Raman lidar and only 20% for the Micropulse lidar due to the difference of pulse energy and the effect of solar irradiance contamination. A complementary study using the cloud fraction derived from the Micropulse lidar for clouds below 5 km and from the Raman lidar for cloud above 5 km allows for better estimation of the total cloud fraction between the ground and the top of the atmosphere. This study presents the diurnal cycle of cloud fraction for each season in comparisons with Long et al.'s (2006) cloud fraction calculation derived from radiative flux analysis.

Dupont, Jean-Charles; Haeffelin, Martial; Morille, Yohann; Comstock, Jennifer M.; Flynn, Connor; Long, Charles N.; Sivaraman, Chitra; Newson, Rob K.

2011-04-01

331

Comparison of MISR and Meteosat 9 Cloud Motion Winds  

NASA Astrophysics Data System (ADS)

A detailed investigation of cloud motion winds from the Multi-angle Imaging SpectroRadiometer (MISR) against atmospheric motion winds from a geostationary satellite was essentially needed. Previously, MISR winds have only been compared to limited radiosonde and wind profiler datasets, or forecast models. Those comparisons already showed relatively good agreements. This study offers the most detailed evaluation of cloud motion winds from MISR to date. Its purely geometric stereo technique retrieves cloud motion and height simultaneously, and is potentially more accurate than traditional satellite winds relying on ancillary information for height assignment. Here, we have analyzed one year of MISR and state-of-the-art Meteosat 9 wind retrievals, producing robust statistics based on 225,155 coincident wind pairs. Retrieval differences have been investigated as a function of quality control metrics, geographic location, season, surface type, cloud elevation, MISR stereo matching technique, and Meteosat 9 height assignment method. We have found that MISR winds have no substantial speed bias compared to Meteosat 9; however, the meridional (MISR along-track) wind components show significantly larger rms differences than the zonal (MISR cross-track) components. There is also a land-ocean contrast with vector differences being larger over land. In general, the worst agreement between wind retrievals is observed in the Tropics. Contrarily, MISR wind heights are systematically larger by 450 m on average than Meteosat 9 heights. Case studies for the Southeast Atlantic Ocean demonstrate that height differences can often be traced to a low bias in the Meteosat 9 brightness temperature height assignment method, which puts winds unreasonably close to the surface, especially in broken cloud fields. Investigating cloud-free land scenes, we have established the minimum error characteristics, and the relationship between along-track wind error and height error in MISR retrievals. Applying these findings to cloudy scenes, we have identified large geographic areas where the observed MISR-Meteosat 9 height differences cannot possibly be explained by MISR height errors alone. Based on our results, we conclude that the MISR wind product, although probably inadequate for weather prediction purposes due to its limited spatial coverage, can still be very useful pinpointing particular situations where geostationary height assignment methods face serious difficulties and, hence, need further improvement. In the future, MISR-like retrieved cloud motion winds over a much wider swath could even be used in numerical weather prediction models to cover e.g. higher latitudes, where no observational data are yet utilized.

Lonitz, K.; Horvath, A.

2009-12-01

332

New capabilities for space-based cloud and aerosols measurements: The Cloud-Aerosol Transport System (CATS)  

NASA Astrophysics Data System (ADS)

Current uncertainties in cloud and aerosol properties limit our ability to accurately model the Earth's climate system and predict climate change. These limitations are due primarily to difficulties in adequately measuring aerosols and clouds on a global scale. NASA's A-Train satellites provide an unprecedented opportunity to address these uncertainties. In particular, the Cloud-Aerosol Lidar Infrared Pathfinder Spaceborne Observations (CALIPSO) satellite provides vertical profiles of cloud and aerosol properties. The CALIOP lidar onboard CALIPSO has reached its seventh year of operation, well past its expected lifetime. The ATLID lidar on EarthCARE is not expected to launch until 2016 or later. If the CALIOP lidar fails before a new mission is operational, there will be a gap in global lidar measurements. The Cloud-Aerosol Transport System (CATS), built at NASA Goddard Space Flight Center as a payload for the International Space Station (ISS), is set to launch in the summer of 2014. CATS is an elastic backscatter lidar with three wavelengths (1064, 532, 355 nm) and HSRL capability at 532 nm. Depolarization measurements will be made at all three wavelengths. The ISS orbit is a 51 degree inclination orbit at an altitude of about 405 km. This orbit provides more comprehensive coverage of the tropics and mid-latitudes than sun-synchronous orbiting sensors, with nearly a three day repeat cycle. Thus, science applications of CATS include cloud and aerosol climate studies, air quality monitoring, and smoke/volcanic plume tracking. The primary science objectives of CATS include: continuing the CALIPSO aerosol and cloud vertical profile data record, providing near real time data to support operational applications such as air quality modeling, and advancing technology in support of future mission development using the HSRL channel. Furthermore, the vertical profiles of cloud and aerosol properties provided by CATS will complement current and future passive satellite sensors. In preparation for launch, simulations of the CATS lidar signal are produced using GEOS5 model data. An example of the simulated CATS attenuated total backscatter for the 532 nm parallel channel is shown in Figure 1 using the GEOS5 model forecast from 15 July 2009. The CATS simulations suggest the signal-to-noise ratio (SNR) and minumim detectable backscatter at 532 nm will be better than CALIPSO during nighttime and very similar during daytime operation. An overview of the CATS mission, science objectives and simulated data will be provided. Figure 1. Simulated CATS attenuated total backscatter for the 532 nm parallel channel using the GEOS5 model forecast data from 15 July 2009.

Yorks, J. E.; McGill, M. J.; Hlavka, D. L.; Palm, S. P.; Hart, W. D.; Nowottnick, E. P.; Vaughan, M.; Rodier, S. D.; Colarco, P. R.; da Silva, A.; Buchard-Marchant, V.

2013-12-01

333

A Cloud-Based Infrastructure for Near-Real-Time Processing and Dissemination of NPP Data  

NASA Astrophysics Data System (ADS)

We are building a scalable cloud-based infrastructure for generating and disseminating near-real-time data products from a variety of geospatial and meteorological data sources, including the new National Polar-Orbiting Environmental Satellite System (NPOESS) Preparatory Project (NPP). Our approach relies on linking Direct Broadcast and other data streams to a suite of scientific algorithms coordinated by NASA's International Polar-Orbiter Processing Package (IPOPP). The resulting data products are directly accessible to a wide variety of end-user applications, via industry-standard protocols such as OGC Web Services, Unidata Local Data Manager, or OPeNDAP, using open source software components. The processing chain employs on-demand computing resources from Amazon.com's Elastic Compute Cloud and NASA's Nebula cloud services. Our current prototype targets short-term weather forecasting, in collaboration with NASA's Short-term Prediction Research and Transition (SPoRT) program and the National Weather Service. Direct Broadcast is especially crucial for NPP, whose current ground segment is unlikely to deliver data quickly enough for short-term weather forecasters and other near-real-time users. Direct Broadcast also allows full local control over data handling, from the receiving antenna to end-user applications: this provides opportunities to streamline processes for data ingest, processing, and dissemination, and thus to make interpreted data products (Environmental Data Records) available to practitioners within minutes of data capture at the sensor. Cloud computing lets us grow and shrink computing resources to meet large and rapid fluctuations in data availability (twice daily for polar orbiters) - and similarly large fluctuations in demand from our target (near-real-time) users. This offers a compelling business case for cloud computing: the processing or dissemination systems can grow arbitrarily large to sustain near-real time data access despite surges in data volumes or user demand, but that computing capacity (and hourly costs) can be dropped almost instantly once the surge passes. Cloud computing also allows low-risk experimentation with a variety of machine architectures (processor types; bandwidth, memory, and storage capacities, etc.) and of system configurations (including massively parallel computing patterns). Finally, our service-based approach (in which user applications invoke software processes on a Web-accessible server) facilitates access into datasets of arbitrary size and resolution, and allows users to request and receive tailored products on demand. To maximize the usefulness and impact of our technology, we have emphasized open, industry-standard software interfaces. We are also using and developing open source software to facilitate the widespread adoption of similar, derived, or interoperable systems for processing and serving near-real-time data from NPP and other sources.

Evans, J. D.; Valente, E. G.; Chettri, S. S.

2011-12-01

334

Cloud and boundary layer structure over San Nicolas Island during FIRE  

NASA Technical Reports Server (NTRS)

The temporal evolution of the structure of the marine boundary layer and of the associated low-level clouds observed in the vicinity of the San Nicolas Island (SNI) is defined from data collected during the First ISCCP Regional Experiment (FIRE) Marine Stratocumulus Intense Field Observations (IFO) (July 1 to 19). Surface, radiosonde, and remote-sensing measurements are used for this analysis. Sounding from the Island and from the ship Point Sur, which was located approximately 100 km northwest of SNI, are used to define variations in the thermodynamic structure of the lower-troposphere on time scales of 12 hours and longer. Time-height sections of potential temperature and equivalent potential temperature clearly define large-scale variations in the height and the strength of the inversion and periods where the conditions for cloud-top entrainment instability (CTEI) are met. Well defined variations in the height and the strength of the inversion were associated with a Cataline Eddy that was present at various times during the experiment and with the passage of the remnants of a tropical cyclone on July 18. The large-scale variations in the mean thermodynamic structure at SNI correlate well with those observed from the Point Sur. Cloud characteristics are defined for 19 days of the experiment using data from a microwave radiometer, a cloud ceilometer, a sodar, and longwave and shortwave radiometers. The depth of the cloud layer is estimated by defining inversion heights from the sodar reflectivity and cloud-base heights from a laser ceilometer. The integrated liquid water obtained from NOAA's microwave radiometer is compared with the adiabatic liquid water content that is calculated by lifting a parcel adiabatically from cloud base. In addition, the cloud structure is characterized by the variability in cloud-base height and in the integrated liquid water.

Albrecht, Bruce A.; Fairall, Christopher W.; Syrett, William J.; Schubert, Wayne H.; Snider, Jack B.

1990-01-01

335

Macrophysical Properties of Tropical Cirrus Clouds from the CALIPSO Satellite and from Ground-based Micropulse and Raman Lidars  

SciTech Connect

Lidar observations of cirrus cloud macrophysical properties over the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) program Darwin, Australia site are compared from the Cloud-Aerosol Lidar and In- frared Pathfinder Satellite Observation (CALIPSO) satellite, the ground-based ARM micropulse lidar (MPL), and the ARM Raman lidar (RL). Comparisons are made using the subset of profiles where the lidar beam is not fully attenuated. Daytime measurements using the RL are shown to be relatively unaffected by the solar background and are therefore suited for checking the validity of diurnal cycles. RL and CALIPSO cloud fraction profiles show good agreement while the MPL detects significantly less cirrus, particularly during the daytime. Both MPL and CALIPSO observations show that cirrus clouds occur less frequently during the day than at night at all altitudes. In contrast, the RL diurnal cy- cle is significantly different than zero only below about 11 km; where it is the opposite sign (i.e. more clouds during the daytime). For cirrus geomet- rical thickness, the MPL and CALIPSO observations agree well and both datasets have signficantly thinner clouds during the daytime than the RL. From the examination of hourly MPL and RL cirrus cloud thickness and through the application of daytime detection limits to all CALIPSO data we find that the decreased MPL and CALIPSO cloud thickness during the daytime is very likely a result of increased daytime noise. This study highlights the vast im- provement the RL provides (compared to the MPL) in the ARM program's ability to observe tropical cirrus clouds as well as a valuable ground-based lidar dataset for the validation of CALIPSO observations and to help im- prove our understanding of tropical cirrus clouds.

Thorsen, Tyler J.; Fu, Qiang; Comstock, Jennifer M.; Sivaraman, Chitra; Vaughan, Mark A.; Winker, D.; Turner, David D.

2013-08-27

336

Development and calibration of a ground-based active collector for cloud- and fogwater  

SciTech Connect

In spring 1985, field experiments were started to study the scavenging processes of atmospheric trace substances. Besides the chemical analysis of precipitation sample, these studies required simultaneous collection of cloud water for chemical analysis. In particular, a ground-based cloud water collector was needed, suitable for use on the top of a TV-tower. Existing designs of ground-based cloud or fogwater samplers be divided into two general classes: a) passive collectors, which utilize the ambient wind to impact the droplets on the collection surface; b) active collectors, which accelerate the droplets to a certain velocity as they approach the collection surface. Teflon-strings are extended between two disks which are 1m apart. The disadvantage of this collector, for these experiments, was that the collector strings are always exposed to the ambient air, so that contamination by aerosol impact during dry periods can not be excluded. Furthermore, because of the length of the strings, impacted droplets need a certain time to drain off, during which they remain exposed to the ambient air stream and continue to scavenge trace gases.

Kins, L.; Junkermann, W.; Meixner, F.X.; Muller, K.P.; Ehhalt, D.H.

1986-04-01

337

Evaluating statistical cloud schemes: What can we gain from ground-based remote sensing?  

NASA Astrophysics Data System (ADS)

Statistical cloud schemes with prognostic probability distribution functions have become more important in atmospheric modeling, especially since they are in principle scale adaptive and capture cloud physics in more detail. While in theory the schemes have a great potential, their accuracy is still questionable. High-resolution three-dimensional observational data of water vapor and cloud water, which could be used for testing them, are missing. We explore the potential of ground-based remote sensing such as lidar, microwave, and radar to evaluate prognostic distribution moments using the "perfect model approach." This means that we employ a high-resolution weather model as virtual reality and retrieve full three-dimensional atmospheric quantities and virtual ground-based observations. We then use statistics from the virtual observation to validate the modeled 3-D statistics. Since the data are entirely consistent, any discrepancy occurring is due to the method. Focusing on total water mixing ratio, we find that the mean ratio can be evaluated decently but that it strongly depends on the meteorological conditions as to whether the variance and skewness are reliable. Using some simple schematic description of different synoptic conditions, we show how statistics obtained from point or line measurements can be poor at representing the full three-dimensional distribution of water in the atmosphere. We argue that a careful analysis of measurement data and detailed knowledge of the meteorological situation is necessary to judge whether we can use the data for an evaluation of higher moments of the humidity distribution used by a statistical cloud scheme.

Grützun, V.; Quaas, J.; Morcrette, C. J.; Ament, F.

2013-09-01

338

A Cloud-Based Internet of Things Platform for Ambient Assisted Living  

PubMed Central

A common feature of ambient intelligence is that many objects are inter-connected and act in unison, which is also a challenge in the Internet of Things. There has been a shift in research towards integrating both concepts, considering the Internet of Things as representing the future of computing and communications. However, the efficient combination and management of heterogeneous things or devices in the ambient intelligence domain is still a tedious task, and it presents crucial challenges. Therefore, to appropriately manage the inter-connection of diverse devices in these systems requires: (1) specifying and efficiently implementing the devices (e.g., as services); (2) handling and verifying their heterogeneity and composition; and (3) standardizing and managing their data, so as to tackle large numbers of systems together, avoiding standalone applications on local servers. To overcome these challenges, this paper proposes a platform to manage the integration and behavior-aware orchestration of heterogeneous devices as services, stored and accessed via the cloud, with the following contributions: (i) we describe a lightweight model to specify the behavior of devices, to determine the order of the sequence of exchanged messages during the composition of devices; (ii) we define a common architecture using a service-oriented standard environment, to integrate heterogeneous devices by means of their interfaces, via a gateway, and to orchestrate them according to their behavior; (iii) we design a framework based on cloud computing technology, connecting the gateway in charge of acquiring the data from the devices with a cloud platform, to remotely access and monitor the data at run-time and react to emergency situations; and (iv) we implement and generate a novel cloud-based IoT platform of behavior-aware devices as services for ambient intelligence systems, validating the whole approach in real scenarios related to a specific ambient assisted living application. PMID:25093343

Cubo, Javier; Nieto, Adrian; Pimentel, Ernesto

2014-01-01

339

Oxygen A-band Spectroscopy: An Overlooked Resource for Ground-Based Inference of Physical and Radiative Properties of Clouds  

NASA Astrophysics Data System (ADS)

It is less risky to infer climatically-relevant properties of clouds by remote sensing using modalities that exploit climatically-important wavelengths. For instance, to study the energy budget a retrieval of cloud optical depth performed in the solar spectrum is more credible than one that uses microwaves, largely because it is sensitive to the 2nd moment of the particle size distribution (PSD) that determines scattering properties---hence cloud reflectivity and transmitivity. On the other hand, estimates of cloud and precipitable water paths based on passive microwave radiometry are more appropriate for hydrological cycle studies, largely because they are primarily sensitive to the key 3rd-order moment of the PSD. Although highly attractive due to superior spatial resolution, mm-wave cloud radar delivers the 6th moment of the PSD, which is not of any immediate use. This active measurement can be processed into information about the desired lower-order PSD moments, but at the cost of making assumptions about the cloud microphysics that may sometimes be questionable. From this risk management standpoint, we will argue that the O2 A-band spectroscopy (759--771~nm) is an under-exploited resource in cloud remote sensing that can constrain retrievals of cloud optical depth or pressure thickness from ground stations such as the US DOE's ARM facilities. In other words, it should work well as a cloud remote sensing asset in synergy with more common ground-based instrumentation, including multi-spectral shortwave radiometers, hyper-spectral thermal IR spectrometers, multi-channel microwave radiometers, and mm-wave radars. But O2 A-band can bring to the table more unique information about clouds. At high enough spectral resolution, A-band spectra have been shown to respond strongly to deviations from the single/unbroken cloud layer scenario, i.e., fully 3D clouds. In particular, A-band has the surprising capability (for a passive sensor) of detecting the presence of more than one cloud layer of significance to the solar energy budget. This feature also ensures that the above-mentioned retrievals of single-layer cloud properties are reliable. As the spatial complexity of the cloudiness increases, ground-based O2 A-band spectroscopy morphs from a 1D (quasi-slab geometry) cloud remote sensing tool into a fully 3D cloud radiative property diagnostic tool. In this new capacity, O2 A-band observations can be brought to bear on the challenging issue of accurately predicting mean shortwave heating rates over large domains, as required in GCM parameterizations of fast physics. Specifically, the performance of GCM cloud and/or shortwave radiation schemes can be evaluated against O2 A-band data, once separated in to their broadband spectral integration and spatial radiation transport parts. In this presentation, we will (1) survey the published technical literature on the cloud remote sensing applications of O2 A-band spectroscopy and (2) describe the emerging ideas of how it can be used to test some key GCM physics, namely, clouds and solar radiation, at the component level. Key differences between ground- and space-based observations will be highlighted.

Davis, A. B.; Min, Q.; Barker, H. W.

2011-12-01

340

Mobile fighting crime device based on information technology by police cloud computing toward pervasive investigations  

Microsoft Academic Search

In this paper, we present the pervasive investigation crime (PIC) system in which this cloud scenario integrates the emerging cloud computing and the radio identification (RFID) technology. This cloud device can give a wider cloud resource including 2G, 3G and 4G cell phone resource that it is suitable for investigator enables to detection a misdeed or suspected vehicle and associated

Ke-Ren Chen; Hung-Jen Tsai

2011-01-01

341

Final height, target height and the community.  

PubMed

Height varies with age, and it varies with historic time. Final height is determined by endocrine parameters and genetics, by nutrition and health, by environmental factors, by birth weight, early growth, BMI, and developmental tempo. European populations of the 19th century were short, but their shortness did not result from growth impairment at all ages. In those days, shortness was mainly due to a significantly blunted adolescent growth spurt. New modelling approaches suggest an independent regulation of adolescent growth and final height: the target for growth and final height appears to be set by the community. In order to test this hypothesis, we formed a geographic network of Switzerland consisting of 169 nodes (district capitals) and 335 connecting edges (roads), and investigated military conscript data obtained between 2004 and 2009. Average height of Swiss military conscripts was 178.2 cm (SD 6.5 cm). But conscripts from first order neighbouring districts were more similar in height than expected. Short stature districts have short, tall stature districts have tall neighbours. We found significant height correlations between 1st (r=0.58), 2nd (r=0.64), 3rd (r=0.45) and even 4th order neighbours (r=0.42). It appears that tall stature communities generate tall people, short stature communities generate short people, and migrants orientate towards the new height target of their host population (community effect on growth). PMID:24940854

Hermanussen, M; Aßmann, C; Groth, D; Staub, K

2014-05-01

342

Vertical Structures of Anvil Clouds of Tropical Mesoscale Convective Systems Observed by CloudSat  

NASA Technical Reports Server (NTRS)

A global study of the vertical structures of the clouds of tropical mesoscale convective systems (MCSs) has been carried out with data from the CloudSat Cloud Profiling Radar. Tropical MCSs are found to be dominated by cloud-top heights greater than 10 km. Secondary cloud layers sometimes occur in MCSs, but outside their primary raining cores. The secondary layers have tops at 6--8 and 1--3 km. High-topped clouds extend outward from raining cores of MCSs to form anvil clouds. Closest to the raining cores, the anvils tend to have broader distributions of reflectivity at all levels, with the modal values at higher reflectivity in their lower levels. Portions of anvil clouds far away from the raining core are thin and have narrow frequency distributions of reflectivity at all levels with overall weaker values. This difference likely reflects ice particle fallout and therefore cloud age. Reflectivity histograms of MCS anvil clouds vary little across the tropics, except that (i) in continental MCS anvils, broader distributions of reflectivity occur at the uppermost levels in the portions closest to active raining areas; (ii) the frequency of occurrence of stronger reflectivity in the upper part of anvils decreases faster with increasing distance in continental MCSs; and (iii) narrower-peaked ridges are prominent in reflectivity histograms of thick anvil clouds close to the raining areas of connected MCSs (superclusters). These global results are consistent with observations at ground sites and aircraft data. They present a comprehensive test dataset for models aiming to simulate process-based upper-level cloud structure around the tropics.

Yuan, J.; Houze, R. A., Jr.; Heymsfield, A.

2011-01-01

343

Vertical Structures of Anvil Clouds of Tropical Mesoscale Convective Systems Observed by CloudSat  

NASA Technical Reports Server (NTRS)

A global study of the vertical structures of the clouds of tropical mesoscale convective systems (MCSs) has been carried out with data from the CloudSat Cloud Profiling Radar. Tropical MCSs are found to be dominated by cloud-top heights greater than 10 km. Secondary cloud layers sometimes occur in MCSs, but outside their primary raining cores. The secondary layers have tops at 6 8 and 1 3 km. High-topped clouds extend outward from raining cores of MCSs to form anvil clouds. Closest to the raining cores, the anvils tend to have broader distributions of reflectivity at all levels, with the modal values at higher reflectivity in their lower levels. Portions of anvil clouds far away from the raining core are thin and have narrow frequency distributions of reflectivity at all levels with overall weaker values. This difference likely reflects ice particle fallout and therefore cloud age. Reflectivity histograms of MCS anvil clouds vary little across the tropics, except that (i) in continental MCS anvils, broader distributions of reflectivity occur at the uppermost levels in the portions closest to active raining areas; (ii) the frequency of occurrence of stronger reflectivity in the upper part of anvils decreases faster with increasing distance in continental MCSs; and (iii) narrower-peaked ridges are prominent in reflectivity histograms of thick anvil clouds close to the raining areas of connected MCSs (superclusters). These global results are consistent with observations at ground sites and aircraft data. They present a comprehensive test dataset for models aiming to simulate process-based upper-level cloud structure around the tropics.

Hence, Deanna A.; Houze, Robert A.

2011-01-01

344

Migrating EO/IR sensors to cloud-based infrastructure as service architectures  

NASA Astrophysics Data System (ADS)

The Night Vision Image Generator (NVIG), a product of US Army RDECOM CERDEC NVESD, is a visualization tool used widely throughout Army simulation environments to provide fully attributed synthesized, full motion video using physics-based sensor and environmental effects. The NVIG relies heavily on contemporary hardware-based acceleration and GPU processing techniques, which push the envelope of both enterprise and commodity-level hypervisor support for providing virtual machines with direct access to hardware resources. The NVIG has successfully been integrated into fully virtual environments where system architectures leverage cloudbased technologies to various extents in order to streamline infrastructure and service management. This paper details the challenges presented to engineers seeking to migrate GPU-bound processes, such as the NVIG, to virtual machines and, ultimately, Cloud-Based IAS architectures. In addition, it presents the path that led to success for the NVIG. A brief overview of Cloud-Based infrastructure management tool sets is provided, and several virtual desktop solutions are outlined. A discrimination is made between general purpose virtual desktop technologies compared to technologies that expose GPU-specific capabilities, including direct rendering and hard ware-based video encoding. Candidate hypervisor/virtual machine configurations that nominally satisfy the virtualized hardware-level GPU requirements of the NVIG are presented , and each is subsequently reviewed in light of its implications on higher-level Cloud management techniques. Implementation details are included from the hardware level, through the operating system, to the 3D graphics APls required by the NVIG and similar GPU-bound tools.

Berglie, Stephen T.; Webster, Steven; May, Christopher M.

2014-06-01

345

Cloud-based bioinformatics workflow platform for large-scale next-generation sequencing analyses  

PubMed Central

Due to the upcoming data deluge of genome data, the need for storing and processing large-scale genome data, easy access to biomedical analyses tools, efficient data sharing and retrieval has presented significant challenges. The variability in data volume results in variable computing and storage requirements, therefore biomedical researchers are pursuing more reliable, dynamic and convenient methods for conducting sequencing analyses. This paper proposes a Cloud-based bioinformatics workflow platform for large-scale next-generation sequencing analyses, which enables reliable and highly scalable execution of sequencing analyses workflows in a fully automated manner. Our platform extends the existing Galaxy workflow system by adding data management capabilities for transferring large quantities of data efficiently and reliably (via Globus Transfer), domain-specific analyses tools preconfigured for immediate use by researchers (via user-specific tools integration), automatic deployment on Cloud for on-demand resource allocation and pay-as-you-go pricing (via Globus Provision), a Cloud provisioning tool for auto-scaling (via HTCondor scheduler), and the support for validating the correctness of workflows (via semantic verification tools). Two bioinformatics workflow use cases as well as performance evaluation are presented to validate the feasibility of the proposed approach. PMID:24462600

Liu, Bo; Madduri, Ravi K; Sotomayor, Borja; Chard, Kyle; Lacinski, Lukasz; Dave, Utpal J; Li, Jianqiang; Liu, Chunchen; Foster, Ian T

2014-01-01

346

Cloud-based bioinformatics workflow platform for large-scale next-generation sequencing analyses.  

PubMed

Due to the upcoming data deluge of genome data, the need for storing and processing large-scale genome data, easy access to biomedical analyses tools, efficient data sharing and retrieval has presented significant challenges. The variability in data volume results in variable computing and storage requirements, therefore biomedical researchers are pursuing more reliable, dynamic and convenient methods for conducting sequencing analyses. This paper proposes a Cloud-based bioinformatics workflow platform for large-scale next-generation sequencing analyses, which enables reliable and highly scalable execution of sequencing analyses workflows in a fully automated manner. Our platform extends the existing Galaxy workflow system by adding data management capabilities for transferring large quantities of data efficiently and reliably (via Globus Transfer), domain-specific analyses tools preconfigured for immediate use by researchers (via user-specific tools integration), automatic deployment on Cloud for on-demand resource allocation and pay-as-you-go pricing (via Globus Provision), a Cloud provisioning tool for auto-scaling (via HTCondor scheduler), and the support for validating the correctness of workflows (via semantic verification tools). Two bioinformatics workflow use cases as well as performance evaluation are presented to validate the feasibility of the proposed approach. PMID:24462600

Liu, Bo; Madduri, Ravi K; Sotomayor, Borja; Chard, Kyle; Lacinski, Lukasz; Dave, Utpal J; Li, Jianqiang; Liu, Chunchen; Foster, Ian T

2014-06-01

347

Investigation of aerosol-cloud interactions in ship tracks using MISR  

NASA Astrophysics Data System (ADS)

Ship tracks serve as a well-known manifestation of marine aerosol-cloud interactions. Whereas ample evidence exists that increased aerosol levels lead to more numerous and smaller cloud droplets and thus higher cloud albedo (the so-called Twomey effect), the response of cloud macrophysics (i.e., cloud thickness, liquid water path) to aerosol perturbations is not as clear-cut. Based on in-situ airborne measurements and A-Train satellite observations of individual ship tracks, Chen et al. (2012) found that under conditions with closed cell structure (i.e., cloud cells ringed by a perimeter of clear air), with sufficiently dry air above cloud tops and/or higher cloud top heights, the cloud albedo can become lower in ship tracks, an effect that had not been previously documented. In light of this study, here we compile an independent Terra MODIS/MISR database of ship tracks, taking advantage of the high spatial resolution multiangle observations uniquely available from MISR to examine the robustness of the previous conclusion on cloud albedo response and to understand the dynamical control on cloud response in detail. MISR provides (a) multiangle stereo imagery that enables retrieval of cloud top height variations with 50 m precision vertically, (b) independent cloud albedo retrievals based on integration of the multiangular radiances, and (c) 1.1-km spatial resolution measurements of the cloud-top wind field. Both the standard MISR data products as well as higher-resolution specialized products generated using the MISR INteractive eXplorer (MINX) tool are used in this study. These attributes make possible a novel, systematic statistical analysis of cloud response in ship tracks.

Chen, Yi-Chun; Garay, Michael; Christensen, Matthew; Nelson, David; Diner, David

2014-05-01

348

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

Microsoft Academic Search

More and more companies begin to provide different kinds of cloud computing services for Internet users at the same time these\\u000a services also bring some security problems. Currently the majority of cloud computing systems provide digital identity for\\u000a users to access their services, this will bring some inconvenience for a hybrid cloud that includes multiple private clouds\\u000a and\\/or public clouds.

Liang Yan; Chunming Rong; Gansen Zhao

2009-01-01

349

COMPARISON OF METEOSAT-8 and NOAA17 BASED CLOUD MICROPHYSICAL PROPERTIES  

Microsoft Academic Search

Clouds and cloud-radiation interactions contribute most to uncertainty in climate predictions in climate model runs. To improve the understanding of cloud processes and the representations in models the IPCC calls for more measurements on cloud properties. Within the SAF on Climate Monitoring (CM-SAF) KNMI developed the algorithms to retrieve cloud microphysical products from Meteosat Second Generation and NOAA-AVHRR satellites. The

R. A. Roebeling; A. J. Feijt

350

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

351

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

352

Wide-angle imaging LIDAR (WAIL): a ground-based instrument for monitoring the thickness and density of optically thick clouds  

Microsoft Academic Search

Traditional lidar provides little information on dense clouds beyond the range to their base (ceilometry), due to their extreme opacity. At most optical wavelengths, however, laser photons are not absorbed but merely scattered out of the beam, and thus eventually escape the cloud via multiple scattering, producing distinctive extended space- and time-dependent patterns which are, in essence, the cloud's radiative

Steven P. Love; A. B. Davis; C. A. Rohde; Cheng Ho

2001-01-01

353

11-Year Warm Cloud Modification Experiment in Maharashtra State, India  

E-print Network

A warm cloud modification experiment was carried out in an area of 4800 Sq.Km in the Pune region,India, during the 11-summer monsoon (June-September) seasons (1973-74, 1976, 1979-86). A double-area cross-over design with area randomization was adopted and an instrumented aircraft was used for seeding and cloud physical measurements. Finely pulverised salt (sodium chloride) particles were released into the monsoon clouds (cumulus and stratocumulus) during aircraft penetrations into the clouds at a height of 200-300 m above the cloud-base. The warm cloud responses to salt seeding are found to be critically dependent on the cloud physical characteristics e.g., vertical thickness and liquid water content. Clouds with vertical thickness greater than 1 km, LWC greater than 0.5 gm/cubic m when seeded with salt particles (modal diameter 10 micro m, concentration 1 per litre of cloud air) produced increase in rainfall of 24 per cent significant at 4 per cent level. Shallow clouds (vertical thickness less than 1 km, LW...

Murty, A S R

1998-01-01

354

Pseudorandom noise code-based technique for cloud and aerosol discrimination applications  

NASA Astrophysics Data System (ADS)

NASA Langley Research Center is working on a continuous wave (CW) laser based remote sensing scheme for the detection of CO2and O2 from space based platforms suitable for ACTIVE SENSING OF CO2 EMISSIONS OVER NIGHTS, DAYS, AND SEASONS (ASCENDS) mission. ASCENDS is a future space-based mission to determine the global distribution of sources and sinks of atmospheric carbon dioxide (CO2). A unique, multi-frequency, intensity modulated CW (IMCW) laser absorption spectrometer (LAS) operating at 1.57 micron for CO2 sensing has been developed. Effective aerosol and cloud discrimination techniques are being investigated in order to determine concentration values with accuracies less than 0.3%. In this paper, we discuss the demonstration of a PN code based technique for cloud and aerosol discrimination applications. The possibility of using maximum length (ML)-sequences for range and absorption measurements is investigated. A simple model for accomplishing this objective is formulated, Proof-of-concept experiments carried out using SONAR based LIDAR simulator that was built using simple audio hardware provided promising results for extension into optical wavelengths.

Campbell, Joel; Prasad, Narasimha S.; Flood, Michael; Harrison, Wallace

2011-06-01

355

Effects of height acceleration on Geosat heights  

NASA Astrophysics Data System (ADS)

A radar altimeter tracking loop, such as that utilized by Geosat, produces height errors in the presence of persistent height acceleration ha. The correction factor for the height error is a function of both the loop feedback parameters and the height acceleration. The correction, in meters, to the sea surface height derived from Geosat is -0.16ha, where ha is in meters per second per second. The errors induced by accelerations are produced primarily by changes in along-track geoid slopes. The nearly circular Geosat orbit and dynamic ocean topography produce small height acceleration values. Methods of using sea surface tracking data from Geosat and altimeter tracker simulation to calculate ha have been evaluated over various time intervals and topographically interesting geoid areas. One of the areas studied in some detail encompasses the Marianas Trench and the Challenger Deep, in the west central Pacific Ocean. Histograms of sea surface height corrections due to range accelerations have also been determined from 24-hour segments of Geosat global data. The findings are that 20% of the Geosat measurements have acceleration-induced errors of ?2 cm, while 8% have errors of ?3 cm.

Hancock, David W.; Brooks, Ronald L.; Lockwood, Dennis W.

1990-03-01

356

Effects of Cloud Horizontal Inhomogeneity and Drizzle on Remote Sensing of Cloud Droplet Effective Radius: Case Studies Based on Large-eddy Simulations  

NASA Technical Reports Server (NTRS)

This study investigates effects of drizzle and cloud horizontal inhomogeneity on cloud effective radius (re) retrievals from the Moderate Resolution Imaging Spectroradiometer (MODIS). In order to identify the relative importance of various factors, we developed a MODIS cloud property retrieval simulator based on the combination of large-eddy simulations (LES) and radiative transfer computations. The case studies based on synthetic LES cloud fields indicate that at high spatial resolution (100 m) 3-D radiative transfer effects, such as illumination and shadowing, can induce significant differences between retrievals ofre based on reflectance at 2.1 m (re,2.1) and 3.7 m (re,3.7). It is also found that 3-D effects tend to have stronger impact onre,2.1 than re,3.7, leading to positive difference between the two (re,3.72.1) from illumination and negative re,3.72.1from shadowing. The cancellation of opposing 3-D effects leads to overall reasonable agreement betweenre,2.1 and re,3.7 at high spatial resolution as far as domain averages are concerned. At resolutions similar to MODIS, however, re,2.1 is systematically larger than re,3.7when averaged over the LES domain, with the difference exhibiting a threshold-like dependence on bothre,2.1and an index of the sub-pixel variability in reflectance (H), consistent with MODIS observations. In the LES cases studied, drizzle does not strongly impact reretrievals at either wavelength. It is also found that opposing 3-D radiative transfer effects partly cancel each other when cloud reflectance is aggregated from high spatial resolution to MODIS resolution, resulting in a weaker net impact of 3-D radiative effects onre retrievals. The large difference at MODIS resolution between re,3.7 and re,2.1 for highly inhomogeneous pixels with H 0.4 can be largely attributed to what we refer to as the plane-parallelrebias, which is attributable to the impact of sub-pixel level horizontal variability of cloud optical thickness onre retrievals and is greater for re,2.1 than re,3.7. These results suggest that there are substantial uncertainties attributable to 3-D radiative effects and plane-parallelre bias in the MODIS re,2.1retrievals for pixels with strong sub-pixel scale variability, and theH index can be used to identify these uncertainties.

Zhang, Zhibo; Ackerman, Andrew S.; Feingold, Graham; Platnick, Steven; Pincus, Robert; Xue, Huiwen

2012-01-01

357

An Autonomous Reliabilit Cloud Comput  

E-print Network

An Autonomous Reliabilit Ami Cloud Comput Department of Computing and Informa Abstract--Cloud computing paradigm allo based access to computing and storages s Internet. Since with advances of Cloud. Keywords- Cloud computing; SLA negotiat I. INTRODUCTION Cloud computing has transferred the services

Buyya, Rajkumar

358

Management of SOA-Based Context-Aware Applications Hosted in a Distributed Cloud Subject to Percentile Constraints  

Microsoft Academic Search

We consider geographically distributed datacen- ters forming a collectively managed cloud computing sys- tem. Multiple SaaS providers host their SOA-based, context- aware applications in the cloud. Typically, the context-aware applications serve multiple classes of customers (end users) classified on economic considerations, which determine the Quality of Service (QoS) received by each class. This need for differentiated QoS for each customer

Keerthana Boloor; Rada Chirkova; Tiia Salo; Yannis Viniotis

2011-01-01

359

Determination of mixing layer heights from ceilometer data  

NASA Astrophysics Data System (ADS)

The Vaisala ceilometer LD40 is an eye-safe commercial lidar. It is designed originally to detect cloud base heights and vertical visibility for aviation safety purposes. The instrument was operated continuously at different measurement campaigns to detect mixing layer height from aerosol backscatter profiles. First results with the CT25K ceilometer were presented last year in the paper SPIE 5235-64 from the environmental measuring campaign in the frame of the BMBF-funded project VALIUM in Hanover, Germany, investigating the air pollution in a street canyon and the surrounding with various sensors. A software for routine retrieval of mixing layer height (MLH) from ceilometer data was developed. A comparison with mixing layer height retrievals from a SODAR and a wind-temperature-radar (WTR) operated in the urban region of Munich will be shown. The three instruments give information that partly agree and partly complement each other. The ceilometer gives information on the aerosol content of the air and the WTR provides a direct measurement of the vertical temperature distribution in the boundary layer. The WTR and the ceilometer add information on the moisture structure of the boundary layer that is not detected by the SODAR which gives information on the thermal structure. On the other hand this comparison validates known techniques by which the MLH is derived from SODAR data. In the absence of low clouds and precipitation ceilometers can estimate the mixing-layer-height fairly well. The potential of the ceilometer, being the smallest instrument among the used ones as LIDAR, SODAR and WTR, will be discussed to be used in future MLH studies.

Schafer, Klaus; Emeis, Stefan M.; Rauch, Andreas; Munkel, Christoph; Vogt, Siegfried

2004-11-01

360

Air Vertical Velocity Distributions of Trade Cumulus and Stratocumulus Clouds from the ARM Mobile Facility CAP-MBL Campaign  

NASA Astrophysics Data System (ADS)

The ARM mobile facility W-band ARM Cloud Radar (WACR) was deployed as part of the Cloud, Aerosol, and Precipitation in the Marine Boundary Layer (CAP-MBL) campaign on the north shore of Graciosa Island, Azores during the summers of 2009 and 2010. Vertical air velocities from cumulus and stratocumulus clouds over this location are retrieved using radar reflectivity and mean Doppler vertical velocity, employing the assumptions of Pinsky et al. (2010) that gravitational settling of hydrometeors is independent of vertical air motion. Cases of trade cumulus and stratocumulus clouds are identified from the CAP-MBL WACR dataset by examining hourly ceilometer-derived cloud base and cloud top heights, cloud top height variability, temporal duration of hydrometeor clusters from the WACR-derived hydrometeor mask, and precipitation type (Remillard et al. 2012). The structure of mean Doppler velocity as a function of reflectivity and cloud properties (e.g. cloud depth and distance below cloud top) are characterized for these two cloud types. Once the settling velocity has been subtracted, the distribution of air vertical velocities are examined. Vertical velocity histograms provide clues to test parameterizations of updrafts and downdrafts within clouds.

Verlinden, K. L.; de Szoeke, S. P.

2013-12-01

361

Interplanetary Charged Dust Magnetic Clouds Striking the Magnetosphere: Coordinated Space-based and Ground-based Observations  

NASA Astrophysics Data System (ADS)

In general, asteroids, meteoroids and dust do not interact with the plasma structures in the solar system, but after a collision between fast moving bodies the debris cloud contains nanoscale dust particles that are charged and behave like heavy ions. Dusty magnetic clouds are then accelerated to the solar wind speed. While they pose no threat to spacecraft because of the particle size, the coherency imposed by the magnetization of the cloud allows the cloud to interact with the Earth’s magnetosphere as well as the plasma in the immediate vicinity of the cloud. We call these clouds Interplanetary Field Enhancements (IFEs). These IFEs are a unique class of interplanetary field structures that feature cusp-shaped increases and decreases in the interplanetary magnetic field and a thin current sheet. The occurrence of IFEs is attributed to the interaction between the solar wind and dust particles produced in inter-bolide collisions. Previous spacecraft observations have confirmed that IFEs move with the solar wind. When IFEs strike the magnetosphere, they may distort the magnetosphere in several possible ways, such as producing a small indentation, a large scale compression, or a glancing blow. In any event if the IFE is slowed by the magnetosphere, the compression of the Earth’s field should be seen in the ground-based magnetic records that are continuously recorded. Thus it is important to understand the magnetospheric response to IFE arrival. In this study, we investigate the IFE structure observed by spacecraft upstream of the magnetosphere and the induced magnetic field perturbations observed by networks of ground magnetometers, including the THEMIS, CARISMA, McMAC arrays in North America and the IMAGE array in Europe. We find that, in a well-observed IFE event on December 24, 2006, all ground magnetometer stations observed an impulse at approximately 1217 UT when the IFE was expected to arrive at the Earth’s magnetopause. These ground stations spread across many latitudes and local times, indicating that the impulse can penetrate magnetic shells as well as propagate along field lines. The equivalent currents in the ionosphere inferred from ground magnetometer measurements show a single vortex with a center located in the morning sector where the IFE impacted the magnetopause. Our observations suggest that the IFE-induced current system in the magnetosphere differs from those caused by sudden impulses.

Russell, C. T.; Chi, Peter; Lai, Hairong

362

Cloud Boundaries During FIRE 2.  

National Technical Information Service (NTIS)

To our knowledge, previous observations of cloud boundaries have been limited to studies of cloud bases with ceilometers, cloud tops with satellites, and intermittent reports by aircraft pilots. Comprehensive studies that simultaneously record information...

T. Uttal, S. M. Shaver, E. E. Clothiaux, T. P. Ackerman

1993-01-01

363

Perturbations in relative humidity in the boundary layer represent a possible mechanism for the formation of small convective clouds  

NASA Astrophysics Data System (ADS)

An air parcel model was developed to study the formation of small convective clouds that appear under conditions of weak updraft and a strong thermal inversion layer above the clouds. Observations suggest that these clouds are characterized by a cloud base height far lower than the lifting condensation level. Considering such atmospheric conditions, the air parcel model shows that these clouds cannot be the result of classical thermals or plumes that are caused by perturbations in the temperature near the surface. We suggest that such clouds are the result of perturbations in the relative humidity of elevated air pockets. These results explain the existence of small clouds that standard methods fail to predict and shed light on processes related to the formation of convective clouds from the lowest end of the size distribution.

Hirsch, E.; Koren, I.; Altaratz, O.; Levin, Z.; Agassi, E.

2013-11-01

364

Climate engineering by manipulation of cloud properties  

NASA Astrophysics Data System (ADS)

Depending on their height, thickness and latitude, clouds can have either a warming or cooling effect on climate. The cooling effect is particularly pronounced for persistent low clouds over low latitude oceans, while the warming effect is most prominent in the case of thin cirrus clouds in the upper troposphere. For both types of clouds, climate engineering has been suggested, but the physical principles are quite different. In the case of marine low clouds, the proposed method (Latham, 1990) consists of injecting sea spray into the turbulent planetary boundary layer and thereby feeding the clouds with additional cloud condensation nuclei (CCN). With more CCN available, the clouds would tend to have more numerous, smaller cloud droplets, resulting in a higher cloud albedo, and hence a larger cooling effect on climate. The cirrus manipulation idea, which is more recent (Mitchell and Finnegan, 2009), is based on the fact that cirrus clouds mainly form by homogeneous freezing at high supersaturations. By injecting very efficient ice nuclei (IN) into regions of cirrus formation, freezing would instead take place on the IN, because of their suppression of the relative humidity threshold. Since the IN number concentration would typically be much lower than that of the haze droplets, the modified cirrus would consist of fewer, larger ice crystals than the unperturbed cirrus. The larger crystals would have a smaller optical depth and larger fall speeds, leading to optically thinner cirrus clouds. Hence, the warming effect of cirrus on climate would be suppressed. We will present an overview of recent research into this intriguing area of investigation, starting with studies focusing on the cloud microphysical effects and radiative forcing. We will then show results obtained from transient simulations in the IMPLICC project (GeoMIP G3-clouds), looking at e.g. changes in the hydrological cycle as a result of climate engineering of clouds. Specifically, we will address the following questions, among others: 1) What is the relative role of the direct and indirect forcing in the case of sea salt injections? 2) How does the climate effect of sea salt injections depend on injected particle size and mass? 3) In what geographical regions should sea salt injections be carried out for maximum global impact? 4) In the case of IN injections into cirrus formation regions, how do the results depend on injection rates? 5) What happens in the transient simulations when climate engineering is switched off ('termination effect')? Finally, we will discuss the limitations of current model studies and suggest directions for future research.

Kristjansson, J. E.; Alterskjær, K.; Storelvmo, T.; Muri, H.; Pfeffer, M. A.; Niemeier, U.; Schmidt, H.

2012-12-01

365

On the optimal method for evaluating cloud products from passive satellite imagery using CALIPSO-CALIOP data: example investigating the CM SAF CLARA-A1 dataset  

NASA Astrophysics Data System (ADS)

A method for detailed evaluation of a new satellite-derived global 28-yr cloud and radiation climatology (Climate Monitoring SAF Cloud, Albedo and Radiation dataset from AVHRR data, named CLARA-A1) from polar orbiting NOAA and Metop satellites is presented. The method combines 1 km and 5 km resolution cloud datasets from the CALIPSO-CALIOP cloud lidar for estimating cloud detection limitations and the accuracy of cloud top height estimations. Cloud detection is shown to work efficiently for clouds with optical thicknesses above 0.30 except for at twilight conditions when this value increases to 0.45. Some misclassifications generating erroneous clouds over land surfaces in semi-arid regions in the sub-tropical and tropical regions are revealed. In addition, a substantial fraction of all clouds remains undetected in the Polar regions during the polar winter season due to the lack of or an inverted temperature contrast between Earth surfaces and clouds. Subsequent cloud top height evaluation took into account the derived information about the cloud detection limits. It was shown that this has fundamental importance for the achieved results. An overall bias of -274 m was achieved compared to a bias of -2762 m if no measures were taken to compensate for cloud detection limitations. Despite this improvement it was concluded that high-level clouds still suffer from substantial height underestimations while the opposite is true for low-level (boundary layer) clouds. The validation method and the specifically collected satellite dataset with optimal matching in time and space are suggested for a wider use in the future for evaluation of other cloud retrieval methods based on passive satellite imagery.

Karlsson, K.-G.; Johansson, E.

2013-02-01

366

A Model-Data Framework for Linking Satellite-Based Data on Vegetation Structure with a Height Structured Ecosystem Model Over North America  

NASA Astrophysics Data System (ADS)

One of the most challenging aspects of ecosystem modeling is to account for the dynamic mosaic of patches on the landscape that result from the processes of disturbance and recovery. In the absence of such information, model stocks and fluxes will vary greatly depending on the prescribed successional state, often assumed to be “potential”. Although great efforts have been made to derive model initial conditions from passive optical remote sensing, many optical metrics, especially those related to LAI, saturate much earlier in succession than do biomass and other structure, such as height. Recent studies have addressed this heterogeneity by combining remotely sensed measurements of vegetation structure, and advanced ecological models that track the dynamics of vegetation structure, to produce accurate estimates of both carbon stocks and fluxes at a set of important study sites. Theoretical studies have demonstrated that a robust model-data framework will require both models and data on vegetation structure sufficient to resolve important environmental gradients and tree-level heterogeneity in forest structure globally. Here, we present a model-data framework for linking satellite-based data on vegetation structure with a height-structured ecosystem model over North America. The core of the framework links GLAS data on vegetation structure and other data sources with the height structured Ecosystem Demography (ED) model. The framework is used to improve model predictions of carbon stocks and fluxes, quantify uncertainties, and prepare for future space-based missions on vegetation structure.

Hurtt, G. C.; Dubayah, R.; Fisk, J.; Moorcroft, P. R.; Lefsky, M. A.

2009-12-01

367

The Vertical Distribution of Thin Features Over the Arctic Analysed from CALIPSO Observations. Part 1; Optically Thin Clouds  

NASA Technical Reports Server (NTRS)

Clouds play a crucial role in the Arctic climate system. Therefore, it is essential to accurately and reliably quantify and understand cloud properties over the Arctic. It is also important to monitor and attribute changes in Arctic clouds. Here, we exploit the capability of the CALIPSO-CALIOP instrument and provide comprehensive statistics of tropospheric thin clouds, otherwise extremely difficult to monitor from passive satellite sensors.We use 4 yr of data (June 2006.May 2010) over the circumpolar Arctic, here defined as 67-82 deg. N, and characterize probability density functions of cloud base and top heights, geometrical thickness and zonal distribution of such cloud layers, separately for water and ice phases, and discuss seasonal variability of these properties. When computed for the entire study area, probability density functions of cloud base and top heights and geometrical thickness peak at 200-400, 1000-2000 and 400-800 m, respectively, for thin water clouds, while for ice clouds they peak at 6-8, 7-9 and 400-1000 m, respectively. In general, liquid clouds were often identified below 2 km during all seasons, whereas ice clouds were sensed throughout the majority of the upper troposphere and also, but to a smaller extent, below 2 km for all seasons.

DeVasthale, Abhay; Tjernstrom, Michael; Karlsson, Karl-Goran; Thomas, Manu Anna; Jones, Colin; Sedlar, Joseph; Omar, Ali H.

2011-01-01

368

Properties of CM-SAF's cloud products -a statistical analysis  

NASA Astrophysics Data System (ADS)

Clouds have a major impact on the earth radiation budget and contribute significantly to the state of the climate system. Additionally, the space-based retrieval of other atmospheric pa-rameters is highly influenced by clouds. Therefor it is essential to assess the strengths and limitations of the satellite-derived cloud properties as accurately as possible. This study deals with those cloud products, that are operationally generated by the EUMETSAT's Satellite Ap-plication Facility on Climate Monitoring (CM-SAF). CM-SAF uses space-based observations from geostationary Meteosat Second Generation (MSG) satellites and polar orbiting NOAA and MetOp satellites to provide satellite-derived geophysical parameter data sets suitable for climate monitoring. CM-SAF's product suite includes cloud parameters, radiation fluxes, sur-face albedo, and atmospheric water vapor, temperature and humidity profiles on a regional and partially on a global scale and thereby focuses on geophysical parameters describing the elements of the energy and water cycle. Since 2005 a threshold technique is used within the CM-SAF to derive various cloud products from satellite data, some are further estimated with an iterative look-up table approach. The properties of CM-SAF's cloud products which are cloud top variables (in here: Cloud Top Height (CTH)), Liquid Water Path (LWP), Cloud Type (CTY), Cloud Optical Thickness (COT) and Cloud Fraction (CFC) are explored and analyzed statistically. The individual products are related to each other via for example two-dimensional frequency distributions in order to verify their consistency. From these statistics average properties for certain classified types are derived, such as LWP-distributions for five different CM-SAF cloud types. Each cloud type can be characterized by an average LWP dis-tribution. Also temporal variations for the cloud properties are studied. The Cloud Top Height product for example shows strong seasonal variations, depending on latitude. Locating the maximal CTH near the equator makes it possible to easily monitor the meridional traveling of the Inter-Tropical Convergence Zone during the the seasons.

Kniffka, Anke; Lockhoff, Maarit; Hollmann, Rainer; Weber, Ralf

369

CONTRIBUTED Green Cloud Computing  

E-print Network

CONTRIBUTED P A P E R Green Cloud Computing: Balancing Energy in Processing, Storage, and Transport to energy consumption and cloud computing seems to be an alternative to office-based computing. By Jayant computing is rapidly expanding as an alternative to conventional office-based computing. As cloud computing

Tucker, Rod

370

Self-organizing nonlinear output (SONO): A neural network suitable for cloud patch-based rainfall estimation at small scales  

NASA Astrophysics Data System (ADS)

Accurate measurement of rainfall distribution at various spatial and temporal scales is crucial for hydrological modeling and water resources management. In the literature of satellite rainfall estimation, many efforts have been made to calibrate a statistical relationship (including threshold, linear, or nonlinear) between cloud infrared (IR) brightness temperatures and surface rain rates (RR). In this study, an automated neural network for cloud patch-based rainfall estimation, entitled self-organizing nonlinear output (SONO) model, is developed to account for the high variability of cloud-rainfall processes at geostationary scales (i.e., 4 km and every 30 min). Instead of calibrating only one IR-RR function for all clouds the SONO classifies varied cloud patches into different clusters and then searches a nonlinear IR-RR mapping function for each cluster. This designed feature enables SONO to generate various rain rates at a given brightness temperature and variable rain/no-rain IR thresholds for different cloud types, which overcomes the one-to-one mapping limitation of a single statistical IR-RR function for the full spectrum of cloud-rainfall conditions. In addition, the computational and modeling strengths of neural network enable SONO to cope with the nonlinearity of cloud-rainfall relationships by fusing multisource data sets. Evaluated at various temporal and spatial scales, SONO shows improvements of estimation accuracy, both in rain intensity and in detection of rain/no-rain pixels. Further examination of the SONO adaptability demonstrates its potentiality as an operational satellite rainfall estimation system that uses the passive microwave rainfall observations from low-orbiting satellites to adjust the IR-based rainfall estimates at the resolution of geostationary satellites.

Hong, Yang; Hsu, Kuo-Lin; Sorooshian, Soroosh; Gao, Xiaogang

2005-03-01

371

Observations of Kelvin-Helmholtz instability at a cloud base with the middle and upper atmosphere (MU) and weather radars  

NASA Astrophysics Data System (ADS)

Using the very high frequency (46.5 MHz) middle and upper atmosphere radar (MUR), Ka band (35 GHz) and X band (9.8 GHz) weather radars, a Kelvin-Helmholtz (KH) instability occurring at a cloud base and its impact on modulating cloud bottom altitudes are described by a case study on 8 October 2008 at the Shigaraki MU Observatory, Japan (34.85°N, 136.10°E). KH braids were monitored by the MUR along the slope of a cloud base gradually rising with time around an altitude of ˜5.0 km. The KH braids had a horizontal wavelength of about 3.6 km and maximum crest-to-trough amplitude of about 1.6 km. Nearly monochromatic and out of phase vertical air motion oscillations exceeding ±3 m s-1 with a period of ˜3 min 20 s were measured by the MUR above and below the cloud base. The axes of the billows were at right angles of the wind and wind shear both oriented east-north-east at their altitude. The isotropy of the radar echoes and the large variance of Doppler velocity in the KH billows (including the braids) indicate the presence of strong turbulence at the Bragg (˜3.2 m) scale. After the passage of the cloud system, the KH waves rapidly damped and the vertical scale of the KH braids progressively decreased down to about 100 m before their disappearance. The radar observations suggest that the interface between clear air and cloud was conducive to the presence of the dynamical shear instability by reducing static stability (and then the Richardson number) near the cloud base. Downward cloudy protuberances detected by the Ka band radar had vertical and horizontal scales of about 0.6-1.1 and 3.2 km, respectively, and were clearly associated with the downward air motions. Observed oscillations of the reflectivity-weighted Doppler velocity measured by the X band radar indicate that falling ice particles underwent the vertical wind motions generated by the KH instability to form the protuberances. The protuberances at the cloud base might be either KH billow clouds or perhaps some sort of mamma. Reflectivity-weighted particle fall velocity computed from Doppler velocities measured by the X band radar and the MUR showed an average value of 1.3 ms-1 within the cloud and in the protuberance environment.

Luce, Hubert; Mega, Tomoaki; Yamamoto, Masayuki K.; Yamamoto, Mamoru; Hashiguchi, Hiroyuki; Fukao, Shoichiro; Nishi, Noriyuki; Tajiri, Takuya; Nakazato, Masahisa

2010-10-01

372

Competition between core and periphery-based processes in warm convective clouds - from invigoration to suppression  

NASA Astrophysics Data System (ADS)

How do changes in the amount and properties of aerosol affect warm clouds? Recent studies suggest that they have opposing effects. Some suggest that an increase in aerosol loading leads to enhanced evaporation and therefore smaller clouds, whereas other studies suggest clouds' invigoration. In this study, using a bin-microphysics cloud model, we propose a theoretical scheme that analyzes the evolution of key processes in warm clouds, under different aerosol loading and environmental conditions, to explain this contradiction. Such a framework reveals a robust reversal in the trend of the clouds' response to an increase in aerosol loading. When aerosol conditions are shifted from super-pristine to slightly pollute, the clouds formed are deeper and have a larger water mass. Such a trend continues up to an optimal concentration (Nop) that allows the cloud to achieve a maximal water mass. Hence, for any concentration below Nop the cloud formed contains less mass and therefore can be considered as aerosol limited, whereas for concentrations greater than Nop cloud periphery processes, such as enhanced entrainment, take over leading to cloud suppression. We show that Nop is a function of the thermodynamic conditions (temperature and humidity profiles). Thus, profiles that favor deeper clouds would dictate larger values of Nop, whereas for profiles of shallow convective clouds, Nop corresponds to the pristine range of the aerosol loading. Such a view of a trend reversal, marked by the optimal concentration, Nop, helps one to bridge the gap between the contradictory results of numerical models and observations. Satellite studies are biased in favor of larger clouds that are characterized by larger Nop values and therefore invigoration is observed. On the other hand, modeling studies are biased in favor of small, mostly trade-like convective clouds, which are characterized by low Nop values (in the pristine range), and therefore cloud suppression is mostly reported as a response to an increase in aerosol loading.

Dagan, G.; Koren, I.; Altaratz, O.

2014-09-01

373

Stereoscopic Height and Wind Retrievals for Aerosol Plumes with the MISR INteractive eXplorer (MINX)  

NASA Technical Reports Server (NTRS)

The Multi-angle Imaging SpectroRadiometer (MISR) instrument aboard the Terra satellite acquires imagery at 275-m resolution at nine angles ranging from 0deg (nadir) to 70deg off-nadir. This multi-angle capability facilitates the stereoscopic retrieval of heights and motion vectors for clouds and aerosol plumes. MISR's operational stereo product uses this capability to retrieve cloud heights and winds for every satellite orbit, yielding global coverage every nine days. The MISR INteractive eXplorer (MINX) visualization and analysis tool complements the operational stereo product by providing users the ability to retrieve heights and winds locally for detailed studies of smoke, dust and volcanic ash plumes, as well as clouds, at higher spatial resolution and with greater precision than is possible with the operational product or with other space-based, passive, remote sensing instruments. This ability to investigate plume geometry and dynamics is becoming increasingly important as climate and air quality studies require greater knowledge about the injection of aerosols and the location of clouds within the atmosphere. MINX incorporates features that allow users to customize their stereo retrievals for optimum results under varying aerosol and underlying surface conditions. This paper discusses the stereo retrieval algorithms and retrieval options in MINX, and provides appropriate examples to explain how the program can be used to achieve the best results.

Nelson, D.L.; Garay, M.J.; Kahn, Ralph A.; Dunst, Ben A.

2013-01-01

374

Effects of height acceleration on Geosat heights  

NASA Technical Reports Server (NTRS)

A radar altimeter tracking loop, such as that utilized by Geosat, produces height errors in the presence of persistent height acceleration h(a). The correction factor for the height error is a function of both the loop feedback parameters and the height acceleration. The correction, in meters, to the sea-surface height (SSH) derived from Geosat is -0.16 h(a), where h(a) is in m/sec per sec. The errors induced by accelerations are produced primarily by changes in along-track geoid slopes. The nearly circular Geosat orbit and dynamic ocean topography produce small h(a) values. One area studied in detail encompasses the Marianas Trench and the Challenger Deep in the west central Pacific Ocean. Histograms of SSH corrections due to range accelerations have also been determined from 24-hour segments of Geosat global data. The findings are that 20 percent of the Geosat measurements have acceleration-induced errors of 2 cm or more, while 8 percent have errors of 3 cm or more.

Hancock, David W., III; Brooks, Ronald L.; Lockwood, Dennis W.

1990-01-01

375

Online Maps and Cloud-Supported Location-Based Services across a Manifold of Devices  

NASA Astrophysics Data System (ADS)

Online mapping, miniaturization of computing devices, the "cloud", Global Navigation Satellite System (GNSS) and cell tower triangulation all coalesce into an entirely novel infrastructure for numerous innovative map applications. This impacts the planning of human activities, navigating and tracking these activities as they occur, and finally documenting their outcome for either a single user or a network of connected users in a larger context. In this paper, we provide an example of a simple geospatial application making use of this model, which we will use to explain the basic steps necessary to deploy an application involving a web service hosting geospatial information and a client software consuming the web service through an API. The application allows an insurance claim specialist to add claims to a cloud-based database including a claim location. A field agent then uses a smartphone application to query the database by proximity, and heads out to capture photographs as supporting documentation for the claim. Once the photos have been uploaded to the web service, a second web service for image matching is called in order to try and match the current photograph to previously submitted assets. Image matching is used as a pre-verification step to determine whether the coverage of the respective object is sufficient for the claim specialist to process the claim. The development of the application was based on Microsoft's® Bing Maps™, Windows Phone™, Silverlight™, Windows Azure™ and Visual Studio™, and was completed in approximately 30 labour hours split among two developers.

Kröpfl, M.; Buchmüller, D.; Leberl, F.

2012-07-01

376

The Research of Satellite Cloud Image Recognition Base on Variational Method and Texture Feature Analysis  

Microsoft Academic Search

Recently, the development of satellite cloud image processing technology has become very quick; the research aspects concentrate on judge the cloud type and classify the cloud mainly. These image processing methods relate to the subject category like image processing and pattern recognition etc; it has become one of the fields of most quickly development in the research of satellite image

Wei Shangguan; Yanling Hao; Zhizhong Lu; Peng Wu

2007-01-01

377

Cloud Based Educational Systems and Its Challenges and Opportunities and Issues  

ERIC Educational Resources Information Center

Cloud Computing (CC) is actually is a set of hardware, software, networks, storage, services an interface combines to deliver aspects of computing as a service. Cloud Computing (CC) actually uses the central remote servers to maintain data and applications. Practically Cloud Computing (CC) is extension of Grid computing with independency and…

Paul, Prantosh Kr.; Lata Dangwal, Kiran

2014-01-01

378

Service Level Agreement-Based Joint Application Environment Assignment and Resource Allocation in Cloud Computing Systems  

E-print Network

in Cloud Computing Systems Yanzhi Wang, Shuang Chen and Massoud Pedram Department of Electrical Engineering and storage. Resource allocation is one of the most important challenges in the cloud computing system algorithms by up to 65.7%. Keywords-cloud computing; application environment; resource allocation; assignment

Pedram, Massoud

379

Macrophysical and microphysical properties of monsoon clouds over a rain shadow region in India from ground-based radiometric measurements  

NASA Astrophysics Data System (ADS)

important radiative properties of clouds such as cloud optical depth (COD) and droplet effective radii (Re) are retrieved from the simultaneous measurements by ground-based multifilter rotating shadowband radiometer (MFRSR) and microwave radiometric profiler (MWRP), colocated at Mahabubnagar, a rain shadow region in southern Indian peninsula. Min and Harisson's (1996) retrieval algorithm is used for the first time to derive monsoon cloud properties in India. COD and liquid water path (LWP) retrieved from two independent instruments of MFRSR and MWRP showed reasonably good correlation. During monsoon (July to September) and postmonsoon (October) months, the maximum probability of occurrence of COD for overcast sky is 20. The maximum probability of occurrence of LWP is 100 gm-2 for water clouds during monsoon months, while October showed maximum occurrence at a lower value of 50 gm-2, where most of the times the cloud bases are above freezing level indicating mixed phase clouds. Maximum Re varied from 14-16 µm (10-12%) to 12 µm (9%) during monsoon to postmonsoon transition with very less probability of occurrence indicating the characteristic feature of this region. A case study showed that the mean Re from ground-based and aircraft measurements are 12.0 ± 3.7 µm and 8.14 ± 1.4 µm, respectively, indicating a fairly good agreement within the experimental constraints. Intercomparison of ground-based and Moderate Resolution Imaging Spectroradiometer (MODIS)-Terra and MODIS-Aqua-derived COD, LWP and Re over the observational site for overcast and warm clouds indicates that on an average, MODIS-retrieved mean COD and LWP are underestimated, while mean Re is overestimated as compared to ground retrievals.

Harikishan, G.; Padmakumari, B.; Maheskumar, R. S.; Pandithurai, G.; Min, Q. L.

2014-04-01

380

Elementary GLOBE Unit: Do You Know that Clouds Have Names?  

NSDL National Science Digital Library

In this book and activities set, the GLOBE Kids share information about the different cloud types by acting out analogies that show what each cloud type looks like and its height in the sky. *Activity 1: Cloud Fun* Students learn about the shape and appearance of cumulus clouds, how to describe them, and what kind of weather is generally happening when these clouds are in the sky. *Activity 2: Cloudscape* Students will be able to identify cloud types using cloud classification names. They will know that the names are based on cloud shape, altitude, and whether they produce precipitation. *Activity 3: To Spread or Not to Spread* Students will be able to identify the three types of contrails and will know that contrails come from airplanes and some contrails become clouds. The Elementary GLOBE unit was designed to introduce K-4 students to the study of Earth System Science. It includes five storybooks and 15 learning activities. The science content provided in the books serves as a springboard to GLOBEâs scientific protocols, and also provides student with an introduction to technology, a basic understanding of the methods of inquiry, and connections to math and literacy skills. Each book has associated hands-on learning activities to support learning exploration.

Hatheway, Becca

2006-01-01

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