Showing papers on "Cloud computing published in 1990"

Principles of Distributed Database Systems

Abstract: This third edition of a classic textbook can be used to teach at the senior undergraduate and graduate levels. The material concentrates on fundamental theories as well as techniques and algorithms. The advent of the Internet and the World Wide Web, and, more recently, the emergence of cloud computing and streaming data applications, has forced a renewal of interest in distributed and parallel data management, while, at the same time, requiring a rethinking of some of the traditional techniques. This book covers the breadth and depth of this re-emerging field. The coverage consists of two parts. The first part discusses the fundamental principles of distributed data management and includes distribution design, data integration, distributed query processing and optimization, distributed transaction management, and replication. The second part focuses on more advanced topics and includes discussion of parallel database systems, distributed object management, peer-to-peer data management, web data management, data stream systems, and cloud computing. New in this Edition: New chapters, covering database replication, database integration, multidatabase query processing, peer-to-peer data management, and web data management. Coverage of emerging topics such as data streams and cloud computing Extensive revisions and updates based on years of class testing and feedback Ancillary teaching materials are available.

Numerical modeling of dynamical and microphysical evolution of an isolated convective cloud―The 19 July 1981 CCOPE cloud

Abstract: A 3-dimensional, anelastic cloud model is applied to the simulation of the July 19, 1981 Cooperative Convective Precipitation Experiment (CCOPE) case study cloud. The model utilizes the bulk water microphysical parameterization technique where number concentrations of cloud ice and snow are taken into account in addition to the mixing ratios of six water species (water vapor, cloud water, cloud ice, rain, snow and graupel/hail). Cloud ice is initiated only by primary nucleation processes (deposition/sorption and heterogeneous and homogeneous freezing of cloud droplets) in the present model. The timing reference was established between the simulation and observations based on a remarkable change in the rise rates of both the observed and simulated cloud tops, and the model results are compared with the observations as a function of time and space. The general features of the cloud (such as cloud top height, cloud size, arrival time of precipitation at the cloud base, radar first echo, etc.) seem to have been well reproduced. Furthermore, the model cloud simulated quite well the location of hydrometeors with respect to the updraft/downdraft structure, the number concentration of precipitating ice particles, updraft velocity and cloud water content along the King Air's penetrating pass. The main features which are not accurately reproduced are the cloud base height, the rise rate of the cloud top and the radar echo near the ground. The cloud base height is too low, which is attributed to the lack of representativeness in the input data taken from the closest radiosonde sounding, while the too rapid rise rate of the cloud top seems to be attributable to the way in which convection is initiated. The rapid decrease in radar reflectivity of the simulated cloud seems to be attributable to inadequate parameterization for rain and graupel.

The influence of clouds on radiation: A climate‐modeling perspective

Abstract: The influence of clouds on the radiation field is reviewed from the point of view of their representation in climate models. Such models are expected to include, in the very near future, condensed water as an additional prognostic variable. We examine how simple parameterizations based on the liquid water content can realistically simulate the radiation field. We focus on the extended low-level clouds for which numerous results of simultaneous radiation and microphysics measurements are available. Particular attention is given to the shortwave absorption in cloud layers because theoretically calculated absorptances are generally weaker than those observed. The problem of the broken field is approached in terms of a relationship between the actual cloud cover and the equivalent cloud cover which gives the same irradiances but using the plane-parallel formalism.

An automated cloud screening algorithm for daytime advanced very high resolution radiometer imagery

Abstract: Valid estimates of sea surface temperature (SST) from the advanced very high resolution radiometer (AVHRR) are critically dependent upon the identification and removal of clouds from parent images. Previous cloud-screening algorithms have demonstrated varying degrees of success, the effectiveness of the particular method used being critically dependent upon cloud type. Contamination from cirrus clouds, for example, has been a major deficiency in previous methods. A robust new algorithm for cloud masking has now been developed which is very effective at removing cloud contamination from images regardless of cloud type. The method, which evaluates every pixel in the image, is statistically reproducible, computationally efficient, and requires no subjective inputs or knowledge of cloud type. The results also show that the algorithm is not regionally specific. The basis for this new method is presented and applications to global AVHRR data, including comparisons with previously used methods, are shown.

Cloud cover analysis with Arctic Advanced Very High Resolution Radiometer data: 2. Classification with spectral and textural measures

Abstract: The spectral and textural characteristics of polar clouds and surfaces for a 7-day summer series of AVHRR data in two Arctic locations are examined, and the results used in the development of a cloud classification procedure for polar satellite data. Since spatial coherence and texture sensitivity tests indicate that a joint spectral-textural analysis based on the same cell size is inappropriate, cloud detection with AVHRR data and surface identification with passive microwave data are first done on the pixel level as described by Key and Barry (1989). Next, cloud patterns within 250-sq-km regions are described, then the spectral and local textural characteristics of cloud patterns in the image are determined and each cloud pixel is classified by statistical methods. Results indicate that both spectral and textural features can be utilized in the classification of cloudy pixels, although spectral features are most useful for the discrimination between cloud classes.

Are cloud amounts estimated from satellite sensor and conventional surface-based observations related?

Abstract: A new basis for the relationship between the (vertical) earthview E of cloud amount and the (whole dome) skycover S of cloud amount has been sought. Over 4500 all-sky camera photographs, representing a considerable range of seasonal and climatological conditions, have been analysed to give rise to a database from which predictive relationships have been established. Cubic functions are the most soundly based both physically and empirically. We find S=0.647 + 2192E−0.461E 2 + 0.037E 3 and E = −0.001 + 0.082S + 0.269S 2−0.019S 3 for the prediction of skycover from earthview and earthview from skycover respectively. If earthview is required from skycover observations then E≈S could be used with little additional error. Hence conventional surface observations of skycover could be compared directly with earthview values derived from satellite sensors.

The peculiar hydrogen cloud in the Virgo Cluster and 3C 273

Abstract: It is shown that the nearest bright extragalactic object to the peculiar hydrogen cloud recently discovered in the Virgo Cluster by Giovanelli and Haynes is the bright QSO 3C 273. Further, it is pointed out that the jet in 3C 273 points in almost the same direction as the major axis of the cloud. Despite the redshift difference, possible physical connections between the cloud and 3C 273 are explored.

Thermodynamic Measurements under a Wall Cloud

Abstract: A storm intercept crew from the University of Oklahoma made a sounding near and underneath the wall cloud of the right-moving member of a splitting thunderstorm in north Texas on 27 May 1985. A comparison between the sounding and an environmental sounding indicated that the low-level moist layer was moister and much deeper near and underneath the wall cloud.

‘Good Gamesumli Pley’, Games of Love in the Cloud of Unknowing

Abstract: Actyues, actyues! (…) medel yow not of contemplatyues. Ye wote not what hem eyleth. Lat hem sit in here rest & in here pley, with the thrid & the best partye of Marye (Cloud 30, 24-29).

The calculation of cloud parameters from AVHRR data

Abstract: This thesis deals with the electromagnetic radiation that is reflected from and emitted by a clear or cloudy terrestrial atmosphere. Calculations are performed in order to estimate the radiation exitant to space in the visible, the near visible, and the two infrared windows at approximately 4 ttm and l1 pm. The NOAA-9 satellite Advanced Very High Resolution Radiometer (AVHRR/2) is used as the data acquisition system. The satellitc AVHRR system is described, as well as future TIROSN satellites. The pre-launch calibration of the radiometer is described in some detail. Posrlaunch calibration is examined using a reflectance difference method. The radiometer gains are shown to have changed by more than 20 vo ftom their pre-launch values. A LOWTRAN based atmospheric model suitable for New 7*aland is developed to provide cloud free transmission values. Atmospheric scattering is shown to contribute negligibly to visible cloud measurements (for 8-bit radiometer resolution). The Channels I to 3 terrestrial reflectance is averaged from more than two years of satellite data. Sea-surface state is examined as a function of windspeed. A method of extracting surface temperature in rugged terrain is developed. Dual temperature measurements at 10.8 and 11.8 pm are used to estimate surface air temperature. The transfer of radiation in a single layer cloud is calculated as a function of cloud thickness, observation/illumination geometry and the effective radius of the cloud drop-distribution. The variation in drop-size is contained in an ensemble of modified-Gamma distributions whose effective radius varies from I to 30 pm with a fixed dispersion of 0.25. n !q{t4que is established which allows effective cloud radius to be estimated from 3.7 pm AVHRR/2 imagery. The radiation values at 0.65 pm and 11.8 pm are used to correcr the 3.7 pm reflectance for variation in cloud thickness and temperature respecdvely. The procedure is limited to wann clouds of moderate optical depth. In addition, the inversion process generates values of cloud top height and temperature, cloud depth and column liquid water conrenr. The method is used to observe the development of orographic cloud formed over the southern half of the North Island of New T;.aland. The inversion results for this type of cloud are in agreement with aircraft measurements carried out by the New 7*aland Meteorological Service andare well fitted by a simple drop-growth model.

Studies of deposition in hill cloud

Abstract: The occurrence of cloud at ground level over hills is particularly difficult to categorise and quantify in complex mountainous terrain, and has constituted a major part of our studies as described below. For routine calculations, concentrations in hill cloud have to be estimated from daily observations at the limited national network of air and precipitation monitoring stations, coupled with meteorological data, leading to additional complications. Further approximations have to be made to calculate deposition rates, and the preliminary estimates of bulk annual deposition given in this paper. However the observed pattern of forest damage raises questions about the large variations in exposure of individual trees, and the relevance of bulk annual deposition estimates averaged over large areas. A tentative approach to identifying particularly damaging episodic conditions for tree foliage is also outlined.

Tactical environmental support system [TESS(3)] satellite cloud analyses

Abstract: : The United States Navy is developing a computer workstation capable of ingesting real time satellite data, called the Tactical Environmental Support System, third generation, or TESS(3). This computer is expected to reside at both ashore and afloat sites. One of the main functions of TESS(3) is to process digital satellite data from the NOAA and DMSP satellites. The baseline processing include the automated scheduling, ingest, navigation and display of the imagery. The Naval Oceanographic and Atmospheric Laboratory (NOARL) is augmenting the capability with cloud analysis software that is capable of detailed cloud analysis and classification.

The Uses of Cloud Models in Weather Modification

Abstract: This paper updates a report to the World Meteorological Organization (WMO) in 1981 made by a "panel of experts" in cloud modeling, chaired by the author. The primary uses of cloud models are reviewed and two tables constructed, one which details the types and uses of cloud models in weather modification and references to the models, and a second table describing the computational tasks involved in running the models. Some outstanding problems are mentioned and reasons given for hope regarding the numerical simulations of cloud seeding effects.

Automated Cloud Typing Using Satellite Imagery

Abstract: : An automated cloud typing algorithm is presented and described whereby 1 km visible and infrared Defense Meteorological Satellite Program (DMSP) data are classified into one of 18 cloud types, including clear. The cloud typing algorithm first converts a satellite visual image into a one-bit binary image that has pixel values at one of two possible grayshades. Spectral and spatial information from the original image is retained in this process; once the one-bit image is constructed it is then analyzed for features that relate to the spatial variations of the clouds in the original satellite image. Overall, cloud type classification results were reasonable; some disturbing failures resulted as well as some success attained. More work is needed before an extensive, globally robust classifier can be developed and implemented in an operational sense into cloud analysis models such as the Air Force Real-time Nephanalysis (RTNEPH).

Fault tolerance support in distributed systems: every silver lining has a cloud

Abstract: The TOBIAS project (Tools for Object Based Integrated Administration of Systems) is about to start implement ing a distributed application. Nothing huge or par t icular ly complicated, but an application that requires a high level of dependabili ty. The project is small, so we would like to use as much off the shelf sof tware as we possibly can. We can't afford to spend much money, we don't want to be guinea pigs and the final product must be portable to many environments and should make use of s tandards wherever possible. Looking round we find we can get high quality, well tested compilers, graphic packages and database systems, we can get software to help us with the security aspects of the system, but we cannot get much that will help with fault tolerance. Yes, we know about all the projects that are p roduc ing and have produced sof tware. Yes, we are aware of the mult i tude of techniques that have been developed. No, few if any of them are of any use for a real, portable application that has to start development today. Yes, we want our cake and to eat it.

Modeling the Variation of Cloud Cover with View Angle Using Space Shuttle Cloud Imagery

Abstract: : This report documents the development of numerous elementary cloud cover models and evaluates the capability of each comparison with actual data. The data are measurements of apparent cloud cover as a function of view angle obtained from space shuttle cloud photographs. Using these data a physically realistic model for cumuliform cloud fields is obtained. The model permits the determination of actual cloud cover from a single-layer totally opaque clouds considered in this research. Additionally, the model is used to specify the probabilities are compared with similar ones obtained from other models of cloud-free line-of-sight commonly in use.

Comparison of satellite based cloud retrieval methods for cirrus and stratocumulus

Abstract: One difficulty in using satellite remote sensing data is the spatial variability of cloud properties on scales smaller than most meteorological satellite fields of view (approx. 4 to 8 km). The variation is examined of satellite derived cloud cover as a function of the satellite sensor spatial resolution for seven cloud cover retrieval methods: (1) Reflectance threshold; (2) Temperature threshold; (3) ISCCP; (4) HBTM (Hybrid Bispectral Threshold Method); (5) NCLE; (6) Spatial coherence; and (7) Functional Box Counting. The first two methods are simple single spectral thresholds which specify a satellite pixel as cloud filled if the measured reflectance is greater than the threshold, or if the measured equivalent blackbody temperature is less than the threshold. The next three methods are bispectral, using one visible wavelength window channel and one thermal infrared wavelength window. The final two algorithms rely on the spatial variability within the cloud field to determine cloud cover. Spatial coherence assumes only that the cloud field occurs in a single layer and that the clouds are optically thick in the infrared window. LANDSAT Thematic Mapper (TM) data is used to test the spatial resolution dependence of the cloud algorithms. The ISCCP bispectral threshold applied to the full resolution data is used as the reference or truth cloud cover, after which the retrieval methods are applied to the spatial resolutions. Studies of the fraction of pixels in the scene at cloud edge, and of the profile of reflectance and temperature near cloud edges indicate an uncertainty in the reference cloud fraction of 1 to 5 percent.